Tong Ren

Four tetranuclear heterometallic compounds, [(Tp)Fe(CN)3]2[Ru2(DMBA)4] (1), [(MeTp)Fe(CN)3]2[Ru2(DMBA)4] (2), [(iBuTp)Fe(CN)3]2[Ru2(DMBA)4] (3), and [(PhTp)Fe(CN)3]2[Ru2(DMBA)4] (4) [DMBA = N,N′-dimethylbenzamidinate, Tp = (hydrotris(pyrazolyl)borate, MeTp = (methyltris(pyrazolyl)borate, iBuTp = (2-methylpropyltris(pyrazolyl)borate, and PhTp = (tris(pyrazolyl)phenylborate)] were prepared from the combination of Ru2(DMBA)4(NO3)2 and an appropriate [(RTp)Fe(CN)3]−. Molecular structures of compounds 1−4 were established using single-crystal X-ray diffraction, and all feature a linear Fe−C≡N−Ru−Ru−N≡C−Fe array. The magnetic study revealed that the temperature dependence of χMT is mostly attributed to the zero-field splitting of the Ru2 center, indicating the absence of strong spin coupling among three metallic centers. The electronic independence was further confirmed by the vis−NIR spectroscopic studies. Also described are the voltammetric properties of these compounds.

Nickel Complexes of C-Substituted Cyclams and Their Activity for CO2 and H+ Reduction

Co-reporter:Timothy D. Cook, Sarah F. Tyler, Caitlyn M. McGuire, Matthias Zeller, Phillip E. Fanwick, Dennis H. Evans, Dennis G. Peters, and Tong Ren

ACS Omega July 2017? Volume 2(Issue 7) pp:3966-3966

Publication Date(Web):July 26, 2017

DOI:10.1021/acsomega.7b00714

Several nickel(II) complexes of cyclams bearing aryl groups on the carbon backbone were prepared and evaluated for their propensity to catalyze the electrochemical reduction of CO2 to CO and/or H+ to H2, representing the first catalytic analysis to be performed on an aryl–cyclam metal complex. Cyclic voltammetry (CV) revealed the attenuation of catalytic activity when the aryl group bears the strong electron-withdrawing trifluoromethyl substituent, whereas the phenyl, p-tolyl, and aryl-free derivatives displayed a range of catalytic activities. The gaseous-product distribution for the active complexes was determined by means of controlled-potential electrolysis (CPE) and revealed that the phenyl derivative is the most active as well as the most selective for CO2 reduction over proton reduction. Stark differences in the activity of the complexes studied are rationalized through comparison of their X-ray structures, absorption spectra, and CPE profiles. Further CV studies on the phenyl derivative were undertaken to provide a kinetic insight.Topics: Catalysts; Crystal structure; Electrochemical analysis; Electrolysis; Molecular structure; Organic compounds and Functional groups; Redox reaction; Redox reaction; Spectra;

An Aerobic Synthetic Approach toward Bis-Alkynyl Cobalt(III) Compounds

Co-reporter:Sean N. Natoli, Matthias Zeller, and Tong Ren

Inorganic Chemistry August 21, 2017 Volume 56(Issue 16) pp:10021-10021

Publication Date(Web):August 9, 2017

DOI:10.1021/acs.inorgchem.7b01577

Reported herein is an expanded investigation into a new method for the preparation of Co(III) cyclam bis-alkynyls (cyclam = 1,4,8,11-tetraazacyclotetradecane) under aerobic, weak base conditions. Treatment of trans-[Co(cyclam)(C2Ar)Cl]Cl-type complexes (Ar = C6F5 (1a), 4-C6H4NMe2 (1b)) with AgOTf in MeCN resulted in the doubly charged complexes [Co(cyclam)(C2Ar)(NCMe)](OTf)2 (Ar = C6F5 (2a), 4-C6H4NMe2 (2b)). These solvento complexes 2a,b undergo rapid alkynylation under aerobic conditions in the presence of an organic base and HC2Ar′ to form the symmetrical or unsymmetrical bis-alkynyl complexes trans-[Co(cyclam)(C2Ar)(C2Ar′)](OTf) (Ar/Ar′ = C6F5 (3a), 4-C6H4NMe2 (3b); Ar = C6F5 and Ar′ = 4-C6H4NMe2 (3c), C2Ph (3d)) in good yields. Molecular structures of the new compounds were established using single-crystal X-ray diffraction. Structural studies revealed a notable trans influence for the Co–Cα bond lengths in the unsymmetrical complex 3c with a bond length of 1.929(7) Å for the electron-withdrawing −C2C6F5 ligand and 1.944(7) Å for −C2-4-C6H4NMe2. The optical HOMO–LUMO gaps for the bis-alkynyl complexes follow the trend 3a (2.83 eV) > 3d (2.77 eV) > 3c (2.70 eV) > 3b (2.64 eV). Although [Co(cyclam)(C2R)2]+ type complexes typically have irreversible electrochemical reductions, reversibility of the Co(+3/+2) couple improves in Co(III) cyclam complexes bearing more electron withdrawing substituents. Voltammetric analysis also revealed a modest NMe2/NMe2 coupling across the Co–alkynyl backbone in 3b, while DFT calculations identified the HOMO in 3b as the superexchange pathway for such coupling.

Study of small oligomers based on Ru2(DMBA)4 and meta-phenylene diethynylene

Co-reporter:Jie-Wen Ying, Carl W. Liskey, Sean N. Natoli, Stella K. Betancourt, Li Liu, Phillip E. Fanwick, Tong Ren

Journal of Organometallic Chemistry 2017 Volumes 849–850(Volumes 849–850) pp:

Publication Date(Web):1 November 2017

DOI:10.1016/j.jorganchem.2017.03.011

•Ru2 (DMBA)4-meta-phenylene diethynylene oligomers were prepared and lower oligomers were isolated.•Structures of monomer and dimer were determined.•Spectroscopic and voltammetric studies revealed a minimum interunit interaction.The reactions between Ru2 (DMBA)4(NO3)2 (DMBA = N,N’-dimethylbenzamidinate) and meta-phenylene diethynylenes bearing 5-ester substituents (-CO2iPr, L1; -CO2Bn, L2) in the presence of Et2NH afforded a series of oligomeric compounds with meta-phenylene diethynylene bridge, namely L-[Ru2 (DMBA)4L]m with m as integers. With L1, the compounds with m = 1–3 (1a, 2a and 3a) were separated and fully characterized. With L2, only the compound with m = 1 (1b) was successfully isolated. In addition to routine spectroscopic characterizations, the structures of both compounds 1b and 2a were determined using single crystal X-ray diffraction. For the series of 1a, 2a and 3a, both the voltammetric and absorption spectroscopic characteristics bear close resemblance to those of simple Ru2 (DMBA)4(C2R)2 compounds, indicating the absence of significant inter-unit electronic couplings in the oligomers.Download high-res image (164KB)Download full-size image

One-dimensional coordination polymers based on [Ru2(DMBA)4]2+ units

Co-reporter:Michael Q. Dequeant, Guangbin Wang, Guo-Lin Xu, Gordon T. Yee, Jing Li, You Song, Tong Ren

Inorganica Chimica Acta 2017 Volume 468(Volume 468) pp:

Publication Date(Web):1 November 2017

DOI:10.1016/j.ica.2017.05.011

•Synthesized new one dimensional coordination polymers 1 and 2 based on [Ru2(DMBA)4]2+ unit.•Determined the X-ray structures of 1 and 2.•Studied the temperature dependence of magnetic susceptibility of Ru2(DMBA)4Cl2 and Ru2(DMBA)4(NO3)2.•Studied the temperature dependence of magnetic susceptibility of 1 and 2.The diruthenium(III) coordination polymers [Ru2(DMBA)4(μ-O,O′-WO4)·2H2O]∞ (1) and [Ru2(DMBA)4(μ-O,O′-1,4-(O2C)2C6H4)·2H2O]∞ (2) were obtained through slow diffusion of Ru2(DMBA)4(NO3)2 in acetonitrile into an aqueous solution containing salts of WO42− and terephthalate, respectively. Both new compounds were characterized using single crystal X-ray diffraction, which revealed the retention of the essential geometrical features of the [Ru2(DMBA)4]2+ units upon the formation of coordination polymers. The temperature-dependence of the magnetic susceptibilities of compounds 1 and 2 and their precursors, Ru2(DMBA)4Cl2 and Ru2(DMBA)4(NO3)2, were measured from 5 to 300 K. Fittings of the χ vs. T data indicate that the magnetic behaviors are mostly due to the zero-field splitting of the S = 1 Ru2 units and there is only a minimal inter-unit coupling in 1 and 2.Download high-res image (86KB)Download full-size image

Diruthenium-DMBA compounds bearing extended cross-conjugated ligands

Co-reporter:Sean N. Natoli, Matthias Zeller, Tong Ren

Journal of Organometallic Chemistry 2017 Volume 847(Volume 847) pp:

Publication Date(Web):1 October 2017

DOI:10.1016/j.jorganchem.2017.03.013

•Ru2(DMBA)4 with extended cross-conjugated alkynyl ligands were prepared.•Structure of Ru2(DMBA)4(L1Tips)2 was determined.•Electronic effect of extended cross-conjugated alkynyl ligands was explored.A series of bis(alkynyl) Ru2(DMBA)4 (DMBA = N,N′-dimethylbenzamidinate) compounds bearing extended, acyclic, cross-conjugated frameworks (number of acetylene units ≥ 3), namely Ru2(DMBA)4(L1SiiPr3)2 (1a, see Scheme 1 for the definition of L1 and L2) and Ru2(DMBA)4(L2SiiPr3)2 (2a), were prepared under aerobic, weak base conditions in good yields. Compounds 1a and 2a showed moderate stability and underwent protiodesilylation aided with the addition of (n-Bu)4NF to the free ethynyl compounds Ru2(DMBA)4(L1H)2 (1b) and Ru2(DMBA)4(L2H)2 (2b), respectively. An X-ray structural study of 1a revealed a significant deviation from the idealized D4h geometry in the coordination sphere of the Ru2 core, accompanied by one of the shortest Ru-Cα bonds reported thus far. Electronic absorption spectral measurements imply that compounds 1a and 1b possess a smaller HOMO-LUMO gap (ca. 1.38 eV), while the gap of 2a and 2b (ca. 1.40 eV) is closer to the range of typical Ru2(DMBA)4(C2R)2-type compounds (ca. 1.42 eV). Cyclic voltammetry measurements indicate a subtle interplay between structural and electronic properties, dependent only on the placement of the intervening olefin across the conjugation pathway.The influence of the cross conjugation on the physical properties of diruthenium compounds was investigated.Download high-res image (227KB)Download full-size image

Synthesis and Investigation of Macrocyclic CrIII Bis(alkynyl) Complexes: Structural and Spectroscopic Properties

Co-reporter:Eileen C. Judkins;Sarah F. Tyler;Matthias Zeller;Phillip E. Fanwick

European Journal of Inorganic Chemistry 2017 Volume 2017(Issue 34) pp:4068-4076

Publication Date(Web):2017/09/15

DOI:10.1002/ejic.201700790

The synthesis and characterization of four new CrIII–bis(alkynyl) complexes bearing the macrocyclic tetraaza ligand DMC (DMC = 5,12-dimethyl-1,4,8,11-tetraazacyclotetradecane) are reported. Complexes trans-[Cr(DMC)(C2R)2]X (R = Ph ([1]X), Fc ([2]X), X = Cl, ClO4. C2H ([3]X′); X′ = ClO4, BPh4) and cis-[Cr(DMC)(C4TMS)2]Cl ([4]Cl) were studied using UV/Vis and FTIR spectroscopy, and their identities were verified with ESI-MS and elemental analysis. The three trans complexes, [1]Cl, [2](ClO4), and [3](BPh4), were structurally characterized using single-crystal X-ray diffraction, which revealed a pseudo-octahedral geometry around the Cr center with the nitrogen atoms occupying the equatorial plane and the alkynyl ligands residing in the apical positions. Spectroscopic analysis of [1]Cl, [3](BPh4) and [4]Cl shows highly structured d–d bands between 320 and 500 nm. All CrIII complexes reported herein are emissive, and detailed studies were performed for [1]Cl, [3](BPh4), and [4]Cl, yielding phosphorescence lifetimes (77 K) of 380, 358, and 160 µs, respectively, and room temperature quantum yields of 0.01 % for complex [1]Cl and 0.15 % for complex [4]Cl. Voltammetric studies of complex [2](ClO4) indicate a weak but discernible coupling between two ferrocenyl groups across the C2–Cr–C2 bridge.

Stepwise Synthesis of Bis-Alkynyl CoIII(cyclam) Complexes under Ambient Conditions

Co-reporter:Sean N. Natoli, Matthias Zeller, and Tong Ren

Inorganic Chemistry 2016 Volume 55(Issue 12) pp:5756

Publication Date(Web):June 6, 2016

DOI:10.1021/acs.inorgchem.6b01076

Reported herein is a new synthetic method for the synthesis of CoIII(cyclam) bis-alkynyls (cyclam = 1,4,8,11-tetraazacyclotetradecane) under aerobic conditions. Upon the treatment of AgOTf in acetonitrile, complex trans-[Co(cyclam)(C2C6H4NMe2)Cl]Cl (1) was converted to trans-[Co(cyclam)(C2C6H4NMe2) (NCMe)](OTf)2 (2), and 2 was in turn reacted with HC2Ar under weakly basic conditions to afford the novel bis-alkynyls trans-[Co(cyclam)(C2C6H4NMe2)(C2Ar)](OTf) (Ar = C6H4NMe2 (3) and C6F5 (4)) in reasonable yields. Voltammetric analysis revealed a modest NMe2/NMe2 coupling across the Co-alkynyl backbone in 3, while DFT calculations identified the HOMO in 3 as the superexchange pathway for such coupling.

Cr(III)-HMC (HMC = 5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane) Alkynyl Complexes: Preparation and Emission Properties

Co-reporter:Sarah F. Tyler, Eileen C. Judkins, You Song, Fan Cao, David R. McMillin, Phillip E. Fanwick, and Tong Ren

Inorganic Chemistry 2016 Volume 55(Issue 17) pp:8736-8743

Publication Date(Web):August 16, 2016

DOI:10.1021/acs.inorgchem.6b01285

Presented here is the chemistry of CrIII alkynyl complexes based on the rac-HMC and meso-HMC ligands (HMC = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Thus far, two pairs of cis/trans-[Cr(rac/meso-HMC)(C2R)2]Cl (R = Ph, C2H/C2SiMe3) complexes have been synthesized from reactions between cis/trans-[Cr(rac/meso-HMC)Cl2]Cl and LiC2R. These complexes were characterized using single crystal X-ray diffraction, UV–vis spectroscopy, FT-IR spectroscopy, and fluorimetry. Single crystal X-ray diffraction studies revealed that these complexes adopt a pseudo-octahedral geometry. The electronic spectra of both the cis- and trans-[Cr(rac/meso-HMC)(C4R′)2]Cl (R′ = H or SiMe3) complexes exhibit d–d bands with pronounced vibronic progression associated with the asymmetric stretch of the Cr-bound C≡C bonds. All of these complexes are phosphorescent and show structured emissions originating from the ligand field excited states.

Synthesis and characterization of Ru2(η2-DmAniF)2(μ-DmAniF)2(μ-OAc)(μ-O)

Co-reporter:Stacey R. Opperwall, Bin Liu, Alice L. Pilo, Zhi Cao, Phillip E. Fanwick, Tong Ren

Polyhedron 2016 Volume 103(Part A) pp:126-130

Publication Date(Web):8 January 2016

DOI:10.1016/j.poly.2015.09.003

A new diruthenium compound, Ru2(η2-DmAniF)2(μ-DmAniF)2(OAc)(O) (1), where DmAniF is N,N′-di(m-methoxyphenyl)formamidinate, was isolated as a secondary product from the reaction between Ru2(DmAniF)3(OAc)Cl and K2CO3, and its formulation was established using both single crystal X-ray diffraction and high resolution mass-spectrometry techniques. Compound 1 has an S = 3/2 ground state, and exhibits an unusually large zero-field splitting (D = 308 cm−1) as revealed by the measurement of temperature dependent magnetism.A new diruthenium compound Ru2(η2-DmAniF)2(μ-DmAniF)2(OAc)(O) was isolated and interesting structural and magnetic properties were revealed.

A Synthetic Approach to Cross-Conjugated Organometallic Complexes Based on geminal-Diethynylethene and CoIII(cyclam)

Co-reporter:Sean N. Natoli, Tyler J. Azbell, Phillip E. Fanwick, Matthias Zeller, and Tong Ren

Organometallics 2016 Volume 35(Issue 20) pp:3594-3603

Publication Date(Web):October 12, 2016

DOI:10.1021/acs.organomet.6b00657

A series of CoIII(cyclam) complexes ([1a,b]Cl, [2a–c]PF6, [3]Cl2, [4a](OTf)4, [4b](PF6)2, and [5]Cl2) (cyclam = 1,4,8,11-tetraazacycloctetradecane) bearing a geminal-diethynylethene ligand (gem-DEE) is reported. Syntheses of these acyclic cross-conjugated complexes were accomplished in satisfactory yields, and structural characterizations established that the geometrical feature of gem-DEE is largely preserved upon metalation. Combined structural and electrochemical studies suggest that the gem-DEE ligand, as a σ-donor, is weaker than phenylethynyl but stronger than butadiynyl in CoIII(cyclam) complexes. Voltammetric analysis indicated a weak but discernible Co–Co coupling across the gem-DEE bridge in [3]Cl2 and [4a](OTf)4, while the addition of a second acetylide in the trans position diminished such coupling in [4b](PF6)2. DFT analysis revealed significant dπ–π mixing around the cobalt centers with extended π-overlap in the highest occupied orbitals and substantial σ-based mixing in the lowest unoccupied orbitals of [3]Cl2 and [4a](OTf)4, the latter of which likely contributes to the weak Co–Co coupling.

CoIII(cyclam) Oligoynyls: Monomeric Oligoynyl Complexes and Dimeric Complexes with an Oligoyn-diyl Bridge

Co-reporter:Timothy D. Cook, Sean N. Natoli, Phillip E. Fanwick, and Tong Ren

Organometallics 2016 Volume 35(Issue 9) pp:1329-1338

Publication Date(Web):April 29, 2016

DOI:10.1021/acs.organomet.6b00219

Described in this work are the preparation and characterization of an extensive family of CoIII(cyclam)-oligoynyl compounds (cyclam = 1,4,8,11-tetraazacyclotetradecane) and elucidation of their electronic structures through DFT calculations. Monomeric Co compounds bearing one oligoynyl, namely, [Co(cyclam)(C2nR)Cl]+ with n = 1–3, and two butadiynyls [Co(cyclam)(C4H)2]+ were prepared from the reactions between [Co(cyclam)Cl2]Cl, Et3N or Et2NH, and the corresponding alkynes. The oligoyndiyl-bridged (μ-C2m) dimers of CoIII(cyclam)Cl with m = 2 and 3 were prepared via the same process by varying alkyne stoichiometry, while those with m = 4 and 6 were prepared using the Glaser coupling reaction. The complexes were prepared in moderate yield (with the exception of m = 6) under mild conditions without requiring an anaerobic or anhydrous environment and are generally stable toward ambient atmosphere. Voltammetric analysis of the dimeric complexes revealed a weak Co–Co interaction through the bridge, which is attenuated by the length of the oligoyne. The orbital origin of the Co–Co interaction is rationalized through DFT analysis.

Synthesis and Electronic Structure of Ru2(Xap)4(Y-gem-DEE) Type Compounds: Effect of Cross-Conjugation

Co-reporter:William P. Forrest; Mohommad M. R. Choudhuri; Stefan M. Kilyanek; Sean N. Natoli; Boone M. Prentice; Phillip E. Fanwick; Robert J. Crutchley

Inorganic Chemistry 2015 Volume 54(Issue 15) pp:7645-7652

Publication Date(Web):July 23, 2015

DOI:10.1021/acs.inorgchem.5b01315

Reported in this Article are the preparation and characterization of a series of new Ru2(II,III) compounds bearing one cross-conjugated σ-geminal-diethynylethene ligand (gem-DEE), namely, Ru2(Xap)4(Y-gem-DEE) (Xap = N,N′-anilinopyridinate (ap) or 2-(3,5-dimethoxy)anilinopyridinate (DiMeOap), and Y = SiiPr3 (1) or H (2)) and [Ru2(ap)4]2(μ-gem-DEE) (3). Compounds 1–3 were characterized by spectroscopic and voltammetric techniques as well as the single crystal X-ray diffraction study of 2a. The X-ray structural data of 2a and the spectroscopic/voltammetric data of compounds 1 and 2 indicate that the gem-DEE ligands are similar to simple alkynyls in their effects on the molecular and electronic structures of the Ru2(Xap)4 moiety. Similar to the previously studied [Ru2(ap)4]2(μ-C2n) type compounds, dimer 3 exhibits pairwise 1e– oxidations and reductions, albeit the potential splits within the pair (ΔE1/2) are significantly smaller than those of [Ru2(ap)4]2(μ-C4). The electronic absorption spectra of the reduced and oxidized derivatives of 1a and 3 were determined using spectroelectrochemistry methods. No discernible intervalence charge transfer transition (IVCT) was detected in the near-IR spectrum for either 3– or 3+, suggesting that the Ru2–Ru2 coupling in these mixed-valence states is weak. DFT calculations on a model compound of 3 yielded six singly occupied molecular orbitals (SOMOs), which have Ru2 contributions similar to those previously calculated for the [Ru2(ap)4]2(μ-C2n) type compounds. Among six SOMOs, SOMO-2 is the only one containing substantial dπ–π(gem-DEE) character across the entire Ru2-μ-gem-DEE-Ru2 linkage, which explains the weakened Ru2–Ru2 coupling.

Turning a New Leaf on Metal-TMC Chemistry: NiII(TMC) Acetylides

Co-reporter:Sarah F. Tyler, Sean N. Natoli, Bess Vlaisavljevich, Phillip E. Fanwick, and Tong Ren

Inorganic Chemistry 2015 Volume 54(Issue 20) pp:10058-10064

Publication Date(Web):September 28, 2015

DOI:10.1021/acs.inorgchem.5b01883

Novel [Ni(TMC)C≡CY]+-type compounds 1–4 [TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane; Y = SiMe3 (1), SiiPr3 (2), Ph (3), and C2H (4)] have been synthesized and characterized. Single-crystal X-ray diffraction studies revealed that these compounds adopt a distorted square-pyramidal geometry, with the acetylide ligand occupying the apical position and a RSRS isomer for the TMC ligand. The room temperature magnetic properties of 1–4 are consistent with an S = 1 ground state, as corroborated by CASSCF and density functional theory calculations, which indicate that the singly occupied molecular orbitals are dz2 and dx2–y2.

Peroxo-dimolybdate catalyst for the oxygenation of organic sulfides by hydrogen peroxide

Co-reporter:Dylan J. Thompson, Zhi Cao, Eileen C. Judkins, Phillip E. Fanwick, Tong Ren

Inorganica Chimica Acta 2015 Volume 437() pp:103-109

Publication Date(Web):1 October 2015

DOI:10.1016/j.ica.2015.08.016

•Synthesized new peroxo dimolybdate 1.•Demonstrated that 1 is both a stoichiometric oxidant and catalyst for H2O2 sulfide oxygenation.•Studied reaction kinetics.•Probed possible transition state using DFT calculations.The reaction between Na2MoO4 and hydrogen peroxide at pH around 6.5 resulted in a novel peroxo-dimolybdate anion [{MoO(O2)2}2(μ-O)]2−, which was isolated as a tetrabutylammonium salt (1). X-ray single crystal diffraction study of 1 revealed that there are two η2-peroxo ligands for each Mo center and a single μ-oxo bridge linking two Mo(VI) centers. Compound 1 can function as a stoichiometric oxidant for the oxygenation of organic sulfides and donate up two active oxygen atoms. Furthermore, 1 catalyzes organic sulfide oxygenation by hydrogen peroxide with 100% utility. The catalytic proficiency of 1 was examined with the oxygenation reactions of substrates including benzyl phenyl sulfide, methyl phenyl sulfide and 4-bromo thioanisole with TOF of 240, 550 and 740 h−1, respectively. Based on the initial rate study of several para-substituted thioanisoles, a reactivity constant (ρ) of −1.06 was obtained, which implies an electron deficient transition state. The initial rate study using thioanisole as the substrate also revealed that the reaction is first order in catalyst but zero order in hydrogen peroxide. Based on these results, a mechanism for the activation of hydrogen peroxide is proposed. The DFT calculations of model catalyst and substrate resulted in an activation energy of 75 kJ mol−1 for the transition state, and a reaction free energy of −69 kJ mol−1.Novel peroxo-dimolybdate anion [{MoO(O2)2}2(μ-O)]2− promotes efficient organic sulfide oxygenation.

Cobalt(III) Bridged by gem-DEE: Facile Access to a New Type of Cross-Conjugated Organometallics

Co-reporter:Sean N. Natoli, Timothy D. Cook, Tara R. Abraham, John J. Kiernicki, Phillip E. Fanwick, and Tong Ren

Organometallics 2015 Volume 34(Issue 21) pp:5207-5209

Publication Date(Web):October 21, 2015

DOI:10.1021/acs.organomet.5b00833

Reported in this communication are CoIII(cyclam) compounds bearing a gem-diethynylethene ligand (gem-DEE; 1–3), including the first examples of 3d metal bimetallic species bridged by gem-DEE (2 and 3). Compounds 1 and 2 were prepared in satisfactory yields under ambient conditions using mild alkylamine bases. X-ray structural characterizations revealed the retention of key geometric features of the gem-DEE ligand upon metalation.

Dimeric Complexes of CoIII(cyclam) with a Polyynediyl Bridge

Co-reporter:Timothy D. Cook, Sean N. Natoli, Phillip E. Fanwick, and Tong Ren

Organometallics 2015 Volume 34(Issue 4) pp:686-689

Publication Date(Web):February 6, 2015

DOI:10.1021/om501272p

Described in this work are the preparation and characterization of a family of polyynediyl-bridged (μ-C2n) dimers of CoIII(cyclam)Cl (cyclam = 1,4,8,11-tetraazacycloctetradecane) for n = 2–4. The complexes are robust to ambient conditions and are prepared under mild conditions without requiring anaerobic or anhydrous environments. Voltammetric analysis revealed weak Co–Co interaction through the bridge, which is attenuated by polyyne length. The orbital origin of the Co–Co interaction has been rationalized through DFT analysis.

Linear trimers of diruthenium linked by polyyndiyl or phenylenediethynyl bridges: A family of unique electronic wires

Co-reporter:Jie-Wen Ying, Zhi Cao, Charles Campana, You Song, Jing-Lin Zuo, Sarah F. Tyler, Tong Ren

Polyhedron 2015 Volume 86() pp:76-80

Publication Date(Web):28 January 2015

DOI:10.1016/j.poly.2014.05.015

A new family of wire-like molecules with butadiyndiyl (1a/b), hexadiyndiyl (2) and phenylenediethynyl (3) bridges linking three diruthenium units have been prepared. The single crystal X-ray diffraction study of 1a revealed structural details of the trimeric compounds, including a distance of 18 Å between two Ru2 termini. Both the voltammetric and spectroscopic data point to an extensive electronic delocalization in trimers 1 and 2, and the lack of delocalization in 3, demonstrating the advantage of linear polyyndiyl in mediating intermetallic electronic couplings. Magnetic studies of compound 1a reveal that a spin transition may occur as the temperature increases from 1.8 to 300 K.Graphical abstractSuccessful modulation of electronic coupling within [Ru2]–linker–[Ru2]–linker–[Ru2] systems with linkers as butadiyn-diyl, hexadiyn-diyl and phenylenediethynyl.

Diruthenium–Polyyn-diyl–Diruthenium Wires: Electronic Coupling in the Long Distance Regime

Co-reporter:Zhi Cao ; Bin Xi ; Diane S. Jodoin ; Lei Zhang ; Steven P. Cummings ; Yang Gao ; Sarah F. Tyler ; Phillip E. Fanwick ; Robert J. Crutchley

Journal of the American Chemical Society 2014 Volume 136(Issue 34) pp:12174-12183

Publication Date(Web):August 12, 2014

DOI:10.1021/ja507107t

Reported herein is a series of Ru2(Xap)4 capped polyyn-diyl compounds, where Xap is either 2-anilinopyridinate (ap) or its aniline substituted derivatives. Symmetric [Ru2(Xap)4](μ-C4k)[Ru2(Xap)4] (compounds 4ka (X = 3-isobutoxy) and 4kc (X = 3,5-dimethoxy) with k = 2, 3, 4, and 5) was obtained from the Glaser coupling reaction of Ru2(Xap)4(C2kH). Unsymmetric [Ru2(Xap)4](μ-C4k+2)[Ru2(ap)4] (compounds 4k+2b with k = 2, 3, and 4) were prepared from the Glaser coupling reaction between Ru2(Xap)4(C2k+2H) and Ru2(ap)4(C2kH). X-ray diffraction study of compound 12c revealed both the sigmoidal topology of the polyyn-diyl bridge and the fine structural detail about the Ru2 cores. Cyclic and differential pulse voltammetric (CV and DPV) measurements and spectroelectrochemical studies revealed that (i) the reduced monoanions [Ru2–C2m–Ru2]−1 (m = 4–8) belong to the Robin–Day class II mixed valent ions and (ii) the electronic coupling between Ru2 termini depends on the length of the polyyn-diyl bridge with an attenuation constant (γ) between 0.12 and 0.15 Å–1. In addition, spin-unrestricted DFT calculations provide insight about the nature of orbitals that mediate the long distance electronic coupling.

Unsymmetric Mononuclear and Bridged Dinuclear CoIII(cyclam) Acetylides

Co-reporter:Timothy D. Cook, Phillip E. Fanwick, and Tong Ren

Organometallics 2014 Volume 33(Issue 18) pp:4621-4624

Publication Date(Web):February 25, 2014

DOI:10.1021/om401231j

Reported herein are the preparation and characterization of a new trans-bis(acetylide) complex of CoIII(cyclam) (cyclam = 1,4,8,11-tetraazacyclotetradecane) bearing two different acetylide ligands (1) and the first example of an all-carbon (C4) bridged dinuclear Co species (2). Structural features of monomeric 1 and dimeric 2 are similar to those of the previously reported CoIII(cyclam) bis(acetylides), and the C≡C and C–C bond lengths of the butadiynediyl bridge in 2 conform to the acetylenic resonance form. The Co centers in the bridged complex 2 do not exhibit a measurable electronic coupling, as revealed by voltammetric measurements, and this behavior is rationalized through the DFT analysis of complexes 1 and 2.

Polyoxometalate [γ-SiW10O34(H2O)2]4− on MCM-41 as catalysts for sulfide oxygenation with hydrogen peroxide

Co-reporter:Dylan J. Thompson, Yang Zhang, Tong Ren

Journal of Molecular Catalysis A: Chemical 2014 Volume 392() pp:188-193

Publication Date(Web):October 2014

DOI:10.1016/j.molcata.2014.05.015

•Compared two immobilization protocols: physisorption (I) and chemisortion (II).•I results in minimal structural degradation but catalyst deactivates upon reuse.•II results in partial structural degradation but shows no deactivation upon reuse.•II is applicable to a variety of organic sulfide substrates.The polyoxometalate (POM) catalyst, [γ-SiW10O34(H2O)2]4−, was introduced into the pores of both as-synthesized (I) and amine functionalized MCM-41 (II). The resultant catalysts were characterized with powder X-ray diffraction, nitrogen sorption, and diffuse-reflectance UV–vis spectroscopy. Both catalysts were tested for reusability through repeated catalytic conversions of methyl phenyl sulfide to methyl phenyl sulfone with hydrogen peroxide. While the physisorbed catalyst (I) exhibits steadily decreasing turnover frequency (TOF), the POM catalyst supported on MCM-41 functionalized with a protonated amine (II) exhibits markedly improved reusability. This chemisorbed catalyst effectively showed no change in TOF between the second (21) and the sixth reactions (22). Additionally, sulfoxidations with catalyst II were investigated with a small set of substrates focusing on compounds including dibenzothiophene, which serves as a model refractory sulfide.

Mesoporous Silica-Supported Ruthenium Oxide Nanoparticulates as Efficient Catalysts for Photoinduced Water Oxidation

Co-reporter:Yang Zhang, Eileen C. Judkins, David R. McMillin, Dhairya Mehta, and Tong Ren

ACS Catalysis 2013 Volume 3(Issue 11) pp:2474

Publication Date(Web):September 30, 2013

DOI:10.1021/cs4006106

The preparation of nanoparticulate RuO2 supported on mesoporous silica SBA-15 was optimized to achieve a uniform dispersion and confinement of RuO2. The supported RuO2 (NP2) has been used as the catalyst for photoinduced water oxidation with Ru(bpy)32+ as the photosensitizer and S2O82– as the sacrificial oxidant. Both NP2 and the previously prepared NP1 achieved O2 yields (based on S2O82–) of 95% and 88% and overall quantum efficiencies of 11.3% and 10.0%, respectively. These benchmark numbers far exceed those of many other metal oxide-based catalysts and previously reported RuO2 catalysts. In addition, NP2 has been recycled up to five times with minimal loss of activity.Keywords: catalyst; mesoporous silica; nanoparticulate; photoinduced water oxidation; RuO2

tert-Butyl Hydroperoxide Oxygenation of Organic Sulfides Catalyzed by Diruthenium(II,III) Tetracarboxylates

Co-reporter:Leslie Villalobos ; Julia E. Barker Paredes ; Zhi Cao

Inorganic Chemistry 2013 Volume 52(Issue 21) pp:12545-12552

Publication Date(Web):October 11, 2013

DOI:10.1021/ic401588j

Diruthenium(II,III) carboxylates Ru2(esp)2Cl (1a), [Ru2(esp)2(H2O)2]BF4 (1b), and Ru2(OAc)4Cl (2) efficiently catalyze the oxygenation of organic sulfides. As noted in a previous work, 1a is active in oxygenation of organic sulfides with tert-butyl hydroperoxide (TBHP) in CH3CN. Reported herein in detail is the oxygenation activity of 1a, 1b, and 2, with the latter being highly selective in oxo-transfer to organic sulfides using TBHP under ambient conditions. Solvent-free oxidation reactions were achieved through dissolving 1a or 1b directly into the substrate with 2 equiv of TBHP, yielding TOF up to 2056 h–1 with 1b. Also examined are the rate dependence on both catalyst and oxidant concentration for reactions with catalysts 1a and 2. Ru2(OAc)4Cl may be kinetically saturated with TBHP; however, Ru2(esp)2Cl does not display saturation kinetics. By use of a series of para-substituted thioanisoles, linear free-energy relationships were established for both 1a and 2, where the reactivity constants (ρ) are negative and that of 1a is about half that of 2. Given these reactivity data, two plausible reaction pathways were suggested. Density functional theory (DFT) calculation for the model compound Ru2(OAc)4Cl·TBHP, with TBHP on the open axial site, revealed elongation of the O–O bond of TBHP upon coordination.

Oxygenation of organic sulfides catalyzed by simple Fe(III) salts

Co-reporter:Leslie Villalobos, Tong Ren

Inorganic Chemistry Communications 2013 Volume 28() pp:52-54

Publication Date(Web):February 2013

DOI:10.1016/j.inoche.2012.11.010

Organic sulfide oxygenation by hydrogen peroxide (H2O2) was effectively accomplished by using iron(III) chloride or iron(III) bromide as the catalyst. The distribution of products between sulfoxide and sulfone is strongly solvent-dependent, and a 100% selectivity for sulfoxide was achieved with FeCl3 in a 1:1 methanol/water mixture.Fe(III) halides catalyze H2O2 oxygenation of sulfides to sulfoxide and sulfone in general, and selectively to the former in 1:1 methanol–water mixture.Highlights► Ability of FeX3 to catalyze the H2O2 oxygenation of organic sulfides ► Solvent dependence of product distribution ► 100% selectivity for sulfoxide using MeOH:H2O mixture solvent

New diruthenium (II,III) compounds bearing terminal olefin groups

Co-reporter:Julia Savchenko, Phillip E. Fanwick, Håkon Hope, Yang Gao, Charu K. Yerneni, Tong Ren

Inorganica Chimica Acta 2013 Volume 396() pp:144-148

Publication Date(Web):24 February 2013

DOI:10.1016/j.ica.2012.11.008

The reaction between Ru2(DmAniF)3(OAc)Cl (DmAniF is N,N′-di(m-methoxyphenyl)formamidinate) and HO2C(CH2)mCHCH2 (m = 3, 4 and 8) under reflux afforded new diruthenium species Ru2(DmAniF)3(O2C(CH2)mCHCH2)Cl (m = 3, 1a; 4, 1b; and 8, 1c). Similarly, the reaction between cis-Ru2(DmAniF)2(OAc)2Cl and HO2C(CH2)mCHCH2 resulted in Ru2(DmAniF)2(O2C(CH2)mCHCH2)2Cl (m = 3, 2a; and 8, 2c). Compounds 2 subsequently underwent an olefin ring closing metathesis reaction catalyzed by (Cy3P)2Cl2Ru(CHPh) to afford the dimerized compounds Ru2(DmAniF)2(μ-O2C(CH2)mCH)2Cl (m = 3, 3a; and 8, 3c). All compounds reported herein were analyzed by voltammetry, high resolution mass spectrometry and Vis–NIR spectroscopy, with the structures of 1c and 2c established through X-ray single crystal diffraction.Graphical abstractCarboxylate exchange reactions between Ru2(DmAniF)4−n(OAc)nCl type compounds and HO2C(CH2)mCHCH2 resulted in new diruthenium species Ru2(DmAniF)4−n(O2C(CH2)mCHCH2)nCl with n = 1 or 2, and the latter underwent further intramolecular ring closing metathesis reaction.Highlights► Preparation of Ru2(DmAniF)4−n(O2C(CH2)mCHCH2)nCl (n = 1 and 2) type compounds. ► Ru2(DmAniF)2(O2C(CH2)mCHCH2)2Cl undergo ring-closing metathesis reactions. ► Potential passivation of H–Si surface with Ru2(DmAniF)3(O2C(CH2)mCHCH2)Cl.

Diruthenium acetylide compounds with masked diazonium capping groups

Co-reporter:Steven P. Cummings, Phillip E. Fanwick, Julia Savchenko, Tong Ren

Journal of Organometallic Chemistry 2013 s 745–746() pp: 93-97

Publication Date(Web):

DOI:10.1016/j.jorganchem.2013.07.034

Diruthenium Alkynyl Compounds with Phosphonate Capping Groups

Co-reporter:Steven P. Cummings, Julia Savchenko, Phillip E. Fanwick, Anastasia Kharlamova, and Tong Ren

Organometallics 2013 Volume 32(Issue 4) pp:1129-1132

Publication Date(Web):February 5, 2013

DOI:10.1021/om301247w

The reaction between Ru2(ap)4Cl (ap = 2-anilinopyridinate) and LiC≡C-4-Ph-P(O)(OtBu)2 afforded Ru2(ap)4-C≡C-4-Ph-P(O)(OtBu)2 (1), which was further reacted with LiC≡C-4-Ph-S(CH2)2SiMe3 to yield trans-(4-Me3Si(CH2)2S-Ph-C≡C)-Ru2(ap)4-C≡C-4-Ph-P(O)(OtBu)2 (2). trans-Ru2(DMBA)4(C≡C-4-Ph-P(O)(OtBu)2)2 (3; DMBA = N,N′-dimethylbenzamidinate) was obtained from the reaction between Ru2(DMBA)4(NO3)2 and either HC≡C-4-Ph-P(O)(OtBu)2 in the presence of Et3N or LiC≡C-4-Ph-P(O)(OtBu)2. Compounds 1–3 were characterized by HR-MS, X-ray diffraction, and voltammetric techniques, which revealed the retention of essential characteristics in molecular and electronic structures upon the phosphonate capping.

New Fe(III)(cyclam) Complexes Bearing Axially Bound geminal-Diethynylethenes

Co-reporter:Zhi Cao, Phillip E. Fanwick, William P. Forrest, Yang Gao, and Tong Ren

Organometallics 2013 Volume 32(Issue 16) pp:4684-4689

Publication Date(Web):August 15, 2013

DOI:10.1021/om400683d

Reported herein are the preparation and characterization of trans-[Fe(cyclam)(X-gem-DEE)2]OTf (where cyclam = 1,4,8,11-tetraazacyclotetradecane, gem-DEE = σ-geminal-diethynylethene, and OTf = trifluoromethanesulfonate) compounds 2a, 2b, and 2c (X = −Ph (2a), −SiiPr3 (2b), and −Fc (2c)), which are the first examples of redox-active 3d metal complexes containing gem-DEE ligands. These compounds were prepared from the reaction between cis/trans-[Fe(cyclam)(OTf)2]OTf (1) and X-gem-DEE-Li. Compounds 2a–2c were characterized by spectroscopic/voltammetric techniques. The trans-orientation of the gem-DEE ligands was established from the single-crystal X-ray diffraction study of 2a. Furthermore, the electronic structures of the model compounds 2a′+ and 2b′+ were analyzed with density-functional-theory calculations, which revealed significant dπ(Fe)−π(gem-DEE) interactions.

New Diruthenium Bis-alkynyl Compounds as Potential Ditopic Linkers

Co-reporter:Julia Savchenko, Zhi Cao, Sean N. Natoli, Steven P. Cummings, Boone M. Prentice, Phillip E. Fanwick, and Tong Ren

Organometallics 2013 Volume 32(Issue 21) pp:6461-6467

Publication Date(Web):October 11, 2013

DOI:10.1021/om400799c

The reaction between Ru2(ap)4-C≡C-4-C6H4-P(O)(OtBu)2 and LiC2X afforded trans-XC2-Ru2(ap)4-C≡C-4-C6H4–P(O)(OtBu)2, where X is −SiMe3 (1), −C2SiMe3 (2), −C4H (3), or −4-C6H4C2SiMe3 (4). Compound 5, trans-(tBuO)2(O)P-C6H4-4-C≡C-Ru2(ap)4-C≡C-4-C6H4SC2H4SiMe3, was obtained from the reaction between Ru2(ap)4-C≡C-4-C6H4SC2H4SiMe3 and excess LiC≡C-4-C6H4-P(O)(OtBu)2. Compounds 1–5 were characterized by elemental analysis, HR-nESI-MS, voltammetric and spectroscopic techniques, and the X-ray diffraction study of 2. The electronic structures of the homologous series 1–3 were investigated using DFT calculations, which revealed both the retention of key features of Ru2 electronic structure upon the introduction of phosphonate capping and subtle dependence on the number of acetylene units (n) across the series.

Silica supported ruthenium oxide nanoparticulates as efficient catalysts for water oxidation

Co-reporter:Yang Zhang and Tong Ren

Chemical Communications 2012 vol. 48(Issue 89) pp:11005-11007

Publication Date(Web):24 Sep 2012

DOI:10.1039/C2CC35272A

Pre-synthesized ruthenium dioxide nanoparticulates (RuO2 NPs) with low level of aggregation were well dispersed in mesoporous silica SBA-15. As a catalyst for water oxidation, the supported RuO2 NPs exhibit excellent catalytic activity and recyclability. The initial turnover frequency (TOF) is to date the highest among comparable RuO2 catalysts.

Diruthenium(III,III) Bis(alkynyl) Compounds with Donor/Acceptor-Substituted geminal-Diethynylethene Ligands

Co-reporter:William P. Forrest ; Zhi Cao ; Kerry M. Hassell ; Boone M. Prentice ; Phillip E. Fanwick

Inorganic Chemistry 2012 Volume 51(Issue 5) pp:3261-3269

Publication Date(Web):February 10, 2012

DOI:10.1021/ic202720c

Reported in this contribution are the preparation and characterization of a series of Ru2(DMBA)4 (DMBA = N,N′-dimethylbenzamidinate) bis(alkynyl) compounds, trans-Ru2(DMBA)4(X-gem-DEE)2 [gem-DEE = σ-geminal-diethynylethene; X = H (1), SiiPr3 (2), Fc (3); 4-C6H4NO2 (4), and 4-C6H4NMe2 (5)]. Compounds 1–5 were characterized by spectroscopic and voltammetric techniques as well as the single-crystal X-ray diffraction studies of 2 and 3. Both the single-crystal structural data of compounds 2 and 3 and the spectroscopic/voltammetric data indicate that the gem-DEE ligands are similar to simple acetylides in their impact on the molecular and electronic structures of the Ru2(DMBA)4 core. Furthermore, density functional theory calculations revealed more extensive π delocalization in aryl-donor-substituted gem-DEEs and that the hole-transfer mechanism will likely dominate the charge delocalization in Ru2-gem-DEE-based wires.

Diruthenium(III,III) Ethynyl-phenyleneimine Molecular Wires: Preparation via On-Complex Schiff Base Condensation

Co-reporter:Steven P. Cummings, Zhi Cao, Phillip E. Fanwick, Anastasia Kharlamova, and Tong Ren

Inorganic Chemistry 2012 Volume 51(Issue 14) pp:7561-7568

Publication Date(Web):June 22, 2012

DOI:10.1021/ic300182h

The diruthenium compound trans-Ru2(DMBA)4(C≡C–C6H4-4-CHO)2 (1; DMBA is N,N′-dimethylbenzamidinate) was prepared from the reaction between Ru2(DMBA)4(NO3)2 and HC≡C–C6H4-4-CHO under the weak base conditions. The aldehyde groups of 1 undergo a condensation reaction with NH2C6H4-4-Y (Y = H and NH2) to afford new compounds trans-Ru2(DMBA)4(C≡C–C6H4-4-CH═N–C6H4-4′-Y)2 (Y = H (2) and NH2 (3)). A related compound, Ru2(DMBA)4(C≡C–C6H4-4-N═C(Me)Fc)2 (4), was also prepared from the reaction between Ru2(DMBA)4(NO3)2 and HC≡C–C6H4–N═C(Me)Fc. X-ray structural studies of compounds 1 and 2 revealed significant deviation from an idealized D4h geometry in the coordination sphere of the Ru2 core. Voltammetric measurements revealed four one electron redox processes for compounds 1–3: the Ru2 centered oxidation and reduction, and a pair of reductions of the imine or aldehyde groups. Compound 4 displays an additional oxidation attributed to the Fc groups. DFT calculations were performed on model compounds to gain a more thorough understanding of the interaction of the organic functional groups across the diruthenium bridge.

Diruthenium(II,III) tetramidates as a new class of oxygenation catalysts

Co-reporter:Leslie Villalobos, Zhi Cao, Phillip E. Fanwick and Tong Ren

Dalton Transactions 2012 vol. 41(Issue 2) pp:644-650

Publication Date(Web):03 Nov 2011

DOI:10.1039/C1DT11530H

Two new diruthenium(II,III) tetramidate compounds, Ru2(NHOCC(CH3)2)4Cl (1) and Ru2(NHOCCH2CH3)4Cl (2) have been prepared and structurally characterized by X-ray crystallography. The activity of promoting sulfide oxygenation using simple oxidants such as hydrogen peroxide (H2O2) and tert-butyl hydroperoxide (TBHP) was studied. A UV-kinetics study indicated that the initial rates of 1 and 2 are comparable to the previously studied diruthenium tetracarboxylates in promoting TBHP oxygenation of methyl phenyl sulfide (MPS). Using excess oxidant and CH3CN as the solvent, organic sulfides MPS and diphenyl sulfide (PPS) were oxidized using 1 mol% of the catalytic species. Compound 1 is more effective than 2 in converting sulfides to sulfoxide under the same conditions. Fast conversion was achieved when the reactions were carried out in the solvent-free conditions, and the major oxidation product was the sulfoxide. The electronic structure of the title compounds was studied with DFT calculations to gain an understanding of the activation of peroxy reagents.

Photoactive Chromium(III)Cyclam Complexes with Axially Bound geminal-Diethynylethenes

Co-reporter:William P. Forrest;Zhi Cao;H. Rhodes Hambrick;Boone M. Prentice;Phillip E. Fanwick;Paul S. Wagenknecht

European Journal of Inorganic Chemistry 2012 Volume 2012( Issue 34) pp:5616-5620

Publication Date(Web):

DOI:10.1002/ejic.201201235

Abstract

Reported herein are the preparation and characterization of trans-[Cr(cyclam)(X-gem-DEE)₂]OTf compounds (gem-DEE = σ-geminal-diethynylethene, OTf = trifluoromethanesulfonate) 1 and 2, which are the first examples of 3d metal complexes containing gem-DEE ligands. All compounds reported herein were characterized by visible, emission, and infrared spectroscopy, electrochemistry (CV and DPV), and high-resolution mass spectrometry, and compound 2 was further studied by single-crystal X-ray diffraction. Both the photophyiscal data and the structural data indicate that the gem-DEE ligands are similar to simple linear alkynyls in their coordination to the Cr^III core. DFT calculations revealed that π delocalization is the most extensive within the SOMO and SOMO–1, in which both the vinyl and free ethynyl groups of the gem-DEE ligand contribute significantly to the π_⟂ orbital that mixes intimately with both the d_yz and d_xz orbitals of the Cr core.

trans-[Fe(cyclam)(C2R)2]+: A New Family of Iron(III) Bis-Alkynyl Compounds

Co-reporter:Zhi Cao, William P. Forrest, Yang Gao, Phillip E. Fanwick, and Tong Ren

Organometallics 2012 Volume 31(Issue 17) pp:6199-6206

Publication Date(Web):August 13, 2012

DOI:10.1021/om300515r

We previously communicated the preparation and characterization of two trans-[Fe(cyclam)(C≡CR)2]OTf compounds, 2b and 2c (where cyclam = 1,4,8,11-tetraazacyclotetradecane, R = −SiiPr3 (2b) or −Ph (2c), and OTf = trifluoromethanesulfonate), which were the first examples of Fe(III) bis-alkynyl complexes. In this work, the series has been expanded to include R = −H (2a), −C2SiMe3 (2d), −C4SiMe3 (2e), and −Fc (2f), which were prepared from the reaction between cis/trans-[Fe(cyclam)(OTf)2]OTf (1) and LiC≡CR (NaC≡CH for 2a). Compounds 2a–2f were characterized by spectroscopic/voltammetric techniques as well as high-resolution mass spectrometry (HR-MS). The trans-orientation of the alkynyl ligands were established from the single-crystal X-ray diffraction studies of 2b–2d. Furthermore, the electronic structures of the model compounds 2a′+, 2d′+, and 2e′+ were analyzed with density-functional calculations, which revealed significant dπ–π(C≡C) interactions.

New Linear π-Conjugated Diruthenium Compounds Containing Axial Tetrathiafulvalene-acetylide Ligands

Co-reporter:Xu-Min Cai, Xiang-Yi Zhang, Julia Savchenko, Zhi Cao, Tong Ren, and Jing-Lin Zuo

Organometallics 2012 Volume 31(Issue 24) pp:8591-8597

Publication Date(Web):December 4, 2012

DOI:10.1021/om300985z

Under the weak base conditions, diruthenium(III) tetrakis-N,N′-dimethylbenzamidinate (DMBA) nitrate (Ru2(DMBA)4(NO3)2) reacted with electroactive tetrathiafulvalene acetylene ligands, HC≡C–TTF1 (5-ethynyl-2-(4,5-dimethyl-1,3-dithiol-2-ylidene)benzo[d][1,3]dithiole) and HC≡C–TTF2 (2-(5-ethynylbenzo[d][1,3]dithiol-2-ylidene)benzo[d][1,3]dithiole), to afford new compounds trans-Ru2(DMBA)4(C≡C–TTF1)2 (1) and trans-Ru2(DMBA)4(C≡C–TTF2)2 (2), respectively. The trans orientation and the planar nature of the ethynyltetrathiafulvalene ligands around the Ru2(III,III) core were supported by the single-crystal X-ray diffraction study of compound 1. Both compounds 1 and 2 and their TTF ligand precursors were characterized with the spectroscopic and voltammetric techniques, which revealed a minimal electronic interaction between the two TTF moieties within the same compound. The electronic structure of trans-Ru2(DMBA)4(C≡C–TTF)2 was analyzed based on a DFT calculation of a model compound, and the resultant distribution of valence MOs is consistent with the voltammetric results.

Modulation of Electronic Couplings within Ru2–Polyyne Frameworks

Co-reporter:Bin Xi ; Isiah P.-C. Liu ; Guo-Lin Xu ; Mohommad M. R. Choudhuri ; Maria C. DeRosa ; Robert J. Crutchley

Journal of the American Chemical Society 2011 Volume 133(Issue 38) pp:15094-15104

Publication Date(Web):August 20, 2011

DOI:10.1021/ja204813h

Dimers of [Ru2(Xap)4] bridged by 1,3,5-hexatriyn-diyl (Xap are 2-anilinopyridinate and its aniline substituted derivatives), [Ru2(Xap)4]2(μ-C6) (1), were prepared. Compounds 1 reacted with 1 equiv of tetracyanoethene (TCNE) to yield the cyclo-addition/insertion products [Ru2(Xap)4]2{μ-C≡CC(C(CN)2)–C(C(CN)2)C≡C} (2) and 1 equiv of Co2(dppm)(CO)6 to yield the η2-Co2 adducts to the middle C≡C bond, [Ru2(Xap)4]2(μ-C6)(Co2(dppm)(CO)4) (3). Voltammetric and spectroelectrochemical studies revealed that (i) two Ru2 termini in 1 are sufficiently coupled with the monoanion (1–) as a Robin–Day class II/III mixed valence species; (ii) the coupling between two Ru2 is still significant but somewhat weakened in 3; and (iii) the coupling between two Ru2 is completely removed by the insertion of TCNE in 2. The attenuation of electronic couplings in 2 and 3 was further explored with both the X-ray diffraction study of representative compounds and spin-unrestricted DFT calculations.

Functionalization of flat Si surfaces with inorganic compounds—Towards molecular CMOS hybrid devices

Co-reporter:Steven P. Cummings, Julia Savchenko, Tong Ren

Coordination Chemistry Reviews 2011 Volume 255(15–16) pp:1587-1602

Publication Date(Web):August 2011

DOI:10.1016/j.ccr.2010.12.030

Covalent modification of flat silicon surfaces is a key step in integrating CMOS technology and molecular electronics that may lead to novel hybrid microelectronic devices. While much of the research has been focused on the functionalization of Si by organic compounds, interest in the functionalization with metal-containing species has intensified in recent years because of the unique attributes of inorganic species including rich redox characteristics and high ground state spins. Described in this short review are (i) synthetic approaches to immobilize inorganic compounds; (ii) structural, spectroscopic and voltammetric techniques for characterization of molecular layers; and (iii) preliminary device fabrication.Research highlights▶ Wet chemistry techniques for molecular passivation by inorganic species. ▶ Modified silicon surfaces for applications such as memory devices. ▶ FT-IR and XPS to extract molecular orientation and composition on Si surfaces. ▶ Determination of electron transfer rates using electrochemical techniques.

New Iron(III) Bis(acetylide) Compounds Based on the Iron Cyclam Motif

Co-reporter:Zhi Cao, William P. Forrest, Yang Gao, Phillip E. Fanwick, Yang Zhang, and Tong Ren

Inorganic Chemistry 2011 Volume 50(Issue 16) pp:7364-7366

Publication Date(Web):July 18, 2011

DOI:10.1021/ic200836v

New trans-[Fe(cyclam)(C≡CR)2]OTf compounds 2a/2b [cyclam = 1,4,8,11-tetraazacyclotetradecane, R = SiiPr3 (a) or Ph (b), and OTf = trifluoromethanesulfonate] were prepared from the reaction between trans-[Fe(cyclam)(OTf)2]OTf (1) and LiC≡CR. The trans arrangement of the acetylide ligands in 2 was established from the X-ray diffraction study of 2a, and the density functional theory calculations revealed significant dπ–π(C≡C) interactions.

Decorating Diruthenium Compounds with Fréchet Dendrons via the Click Reaction

Co-reporter:William P. Forrest, Zhi Cao, Wei-Zhong Chen, Kerry M. Hassell, Anastasia Kharlamova, Greta Jakstonyte, and Tong Ren

Inorganic Chemistry 2011 Volume 50(Issue 19) pp:9345-9353

Publication Date(Web):September 8, 2011

DOI:10.1021/ic200929r

A series of dendronized-Ru2 compounds were prepared using the Cu(I)-catalyzed 1,3-dipolar cycloaddition (click reaction) between the terminal azides of azidopoly(benzyl ether) dendrons ([Dn]-N3, n = 0–3) and Ru2 units bearing one or two terminal ethynes, Ru2(D(3,5-Cl2Ph)F)4–m(DMBA-4-C2H)mCl with m = 1 and 2, and D(3,5-Cl2Ph)F and DMBA-4-C2H as N,N′-bis(3,5-dichloro-phenyl)formamidinate and N,N′-dimethyl-4-ethynylbenzamidinate, respectively. The resultant Ru2(D(3,5-Cl2Ph)F)4–m(DMBA-Dn)mCl compounds were further functionalized by the axial ligand displacement of Cl by -C2Ph to yield new compounds Ru2(D(3,5-Cl2Ph)F)4–m(DMBA-Dn)m(C2Ph)2 (where m = 1 and 2; n = 0 and 1). All Ru2 compounds reported herein were analyzed via mass spectrometry, voltammetry, and UV–visible and fluorescence spectroscopy. Density-functional theory (DFT) calculations were performed on a model compound to gain more insight into the molecular orbital energy levels possibly associated with the photophysical data obtained and presented herein.

Diruthenium σ-iminophenylacetylide complexes from on-complex Schiff base condensation

Co-reporter:Steven P. Cummings, Alex R. Geanes, Phillip E. Fanwick, Anastasia Kharlamova, Tong Ren

Journal of Organometallic Chemistry 2011 696(25) pp: 3955-3960

Publication Date(Web):

DOI:10.1016/j.jorganchem.2011.02.018

DFT Study of Electronic Properties of 3d Metal Complexes of σ-Geminal Diethynylethenes (gem-DEEs)

Co-reporter:Zhi Cao and Tong Ren

Organometallics 2011 Volume 30(Issue 2) pp:245-250

Publication Date(Web):December 21, 2010

DOI:10.1021/om100870k

A density functional theory (DFT) analysis has been carried out to evaluate the structural and electronic properties of bimetallic compounds bridged by geminal diethynylethene (gem-DEE). Five stable equilibrium structures of the [M]−gem-DEE−[M] type ([M] = −M(H2PCH2CH2PH2)2Me) were obtained for the first-row transition metals, namely Ti, V, Cr, Fe, and Ni, using DFT at the B3LYP/LanL2DZ level. While the d orbitals in the Ti and Ni compounds exhibited minimal interactions with the gem-DEE-based orbitals, extensive interactions between the dπ orbitals and π(DEE) orbitals were found for the V, Cr, and Fe compounds. A detailed natural bond orbital (NBO) analysis revealed that the electronic delocalization in [M]−gem-DEE−[M] is attributed to both the σ orbitals along the DEE backbone and π orbitals perpendicular to the DEE plane.

Bimetallic Organometallic Compounds of σ-gem-Diethynylethene (gem-DEE) Ligands: trans-Ru2(DMBA)4(gem-DEE)2

Co-reporter:William P. Forrest, Zhi Cao, Phillip E. Fanwick, Kerry M. Hassell, and Tong Ren

Organometallics 2011 Volume 30(Issue 8) pp:2075-2078

Publication Date(Web):March 29, 2011

DOI:10.1021/om200029v

Reported herein are the preparation and characterization of trans-Ru2(DMBA)4(gem-DEE)2 compounds 1a/1b (gem-DEE = σ-geminal-diethynylethene), the first examples of redox active metal complexes containing gem-DEE ligands. DFT calculations revealed a significant mixing between the π(DEE) and π*/π(Ru2) orbitals in both the HOMO and HOMO-1 of the model compound 1′.

New diruthenium complexes formed via modification with 1,1′-ferrocene dicarboxylic acid

Co-reporter:Darryl A. Boyd, Phillip E. Fanwick, Tong Ren

Inorganica Chimica Acta 2011 370(1) pp: 198-202

Publication Date(Web):

DOI:10.1016/j.ica.2011.01.042

Diruthenium Compounds Bearing Equatorial Fc-containing Ligands: Synthesis and Electronic Structure

Co-reporter:Darryl A. Boyd, Zhi Cao, You Song, Tian-Wei Wang, Phillip E. Fanwick, Robert J. Crutchley, and Tong Ren

Inorganic Chemistry 2010 Volume 49(Issue 24) pp:11525-11531

Publication Date(Web):November 11, 2010

DOI:10.1021/ic101628z

Previously, the synthesis of compounds Ru2(D(3,5-Cl2Ph)F)4−n(O2CFc)nCl (n = 1, 3a; 2, 4a), where D(3,5-Cl2Ph)F is N,N′-di(3,5-dichlorophenyl)formamidinate, from the carboxylate exchange reactions between Ru2(D(3,5-Cl2Ph)F)4−n(OAc)nCl and ferrocene carboxylic acid was communicated. Reported herein is the preparation of analogous compounds Ru2(DmAniF)4−n(O2CFc)nCl (n = 1, 3b; 2, 4b), where DmAniF is N,N′-di(3-methoxyphenyl)formamidinate, from Ru2(DmAniF)4−n(OAc)nCl. Compounds 3 and 4 were characterized with various techniques including X-ray structural determinations of 3a and 4a. Voltammetric behaviors of compounds 3 and 4 were investigated, and stepwise one-electron ferrocene oxidations were observed for both compounds 4a and 4b. Spectral analysis of the monocations [4]+ indicated that they are the Robin−Day class II mixed valent [Fc···Fc]+ species. Measurement and fitting of magnetic data (χT) of 4a between 2 and 300 K revealed a typical zero-field splitting of a S = 3/2 center with D = 77 cm−1, while those of [4a]BF4 are consistent with the presence of S = 3/2 (Ru2) and S = 1/2 (Fc+) centers that are weakly coupled (zJ = −0.76 cm−1).

Fc-Fc Electronic Interaction through Equatorial Pathways of a Diruthenium Core

Co-reporter:Darryl A. Boyd ; Robert J. Crutchley ; Phillip E. Fanwick

Inorganic Chemistry 2010 Volume 49(Issue 4) pp:1322-1324

Publication Date(Web):December 28, 2009

DOI:10.1021/ic902378h

Diruthenium compounds bearing one (3) and two (4) ferrocene carboxylate ligands were prepared and characterized, and the electronic coupling between two equatorially adjacent Fc centers in compound 4 is significant, but weaker than those between Fc centers placed on the opposite axial sites.

Dirhenium Compounds Supported by N,N ′-Dimethylbenzamidinate: Formation of Linear Polymers via Axial Ligation

Co-reporter:Michael Q. Dequeant

Journal of Cluster Science 2010 Volume 21( Issue 3) pp:291-300

Publication Date(Web):2010 September

DOI:10.1007/s10876-010-0284-z

The reaction between Re2(DMBA)4Cl2 and NaN(CN)2 resulted in Re2(DMBA)4(N(CN)2)2 (1a), where DMBA is N,N′-dimethylbenzamidinate. Molecular compounds Re2(DMBA)4(ReO4)2 (1b) and Re2(DMBA)4(OP(O)(OH)Ph)2 (1c) were obtained through the reactions between Re2(DMBA)4(NO3)2 and the respective monoanion. The dirhenium(III) coordination polymers [Re2(DMBA)4(μ-O,O′-WO4)·2H2O]∞ (2a), [Re2(DMBA)4(μ-O,O′-MoO4)·2H2O]∞ (2b), and [Re2(DMBA)4(μ-O,O′-1,4-(O2C)2C6H4)·2H2O]∞ (2c) were similarly prepared through slow diffusion of Re2(DMBA)4(NO3)2 in acetonitrile into aqueous solution containing the respective dianion. All new compounds were characterized with single crystal X-ray diffraction, which revealed the retention of the essential structural features of Re2(DMBA)4 unit upon the formation of coordination polymers.

Diruthenium Phenylacetylide Complexes Bearing para-/meta-Amino Phenyl Substituents

Co-reporter:Steven P. Cummings, Zhi Cao, Carl W. Liskey, Alex R. Geanes, Phillip E. Fanwick, Kerry M. Hassell and Tong Ren

Organometallics 2010 Volume 29(Issue 12) pp:2783-2788

Publication Date(Web):June 1, 2010

DOI:10.1021/om100263c

Presented herein is the synthesis and characterization of four diruthenium(II,III) compounds of formulas Ru2(Xap)4(C≡C-C6H4-4-NH2) (Xap is 2-anilinopyridinate, 1a; and 2-(3,5-dimethoxy)anilinopyridinate, 1b) and Ru2(Xap)4(C≡C-C6H4-3-NH2) (2a/2b). X-ray structural studies of compounds 1b and 2a revealed minimal changes in the coordination sphere of the Ru2 core. Voltammetric measurements showed that compounds 1 exhibit three one-electron redox processes: a reversible reduction of Ru2, a reversible oxidation of Ru2, and a quasi-reversible oxidation of an amino group. Compounds 2 display the same Ru2-based redox processes but not the −NH2 oxidation. Compounds 1a/1b were successfully converted to the corresponding diazonium salts [Ru2(Xap)4-(C≡C-C6H4-4-N2)](BF4) (3a/3b) via oxidation by nitrosonium tetrafluoroborate, which was generated in situ from t-BuONO and BF3. However, the attempt to convert compounds 2 to the corresponding diazonium salts was unsuccessful. DFT calculations of model compounds were performed to rationalize some unusual structural and electrochemical characteristics observed for compounds 1/2.

Linear Trimer of Diruthenium Linked by Butadiyn-Diyl Units: A Unique Electronic Wire

Co-reporter:Jie-Wen Ying Dr.;IsiahPo-Chun Liu Dr.;Bin Xi Dr.;You Song Dr.;Charles Campana Dr.;Jing-Lin Zuo Dr. Dr.

Angewandte Chemie International Edition 2010 Volume 49( Issue 5) pp:954-957

Publication Date(Web):

DOI:10.1002/anie.200904674

Linear Trimer of Diruthenium Linked by Butadiyn-Diyl Units: A Unique Electronic Wire

Co-reporter:Jie-Wen Ying Dr.;IsiahPo-Chun Liu Dr.;Bin Xi Dr.;You Song Dr.;Charles Campana Dr.;Jing-Lin Zuo Dr. Dr.

Angewandte Chemie 2010 Volume 122( Issue 5) pp:966-969

Publication Date(Web):

DOI:10.1002/ange.200904674

Spectroscopy and Electronic Structures of Ru2(ap)4-alkynyl Compounds

Co-reporter:Lei Zhang, Bin Xi, Isiah Po-Chun Liu, M. M. R. Choudhuri, Robert J. Crutchley, James B. Updegraff, John D. Protasiewicz and Tong Ren

Inorganic Chemistry 2009 Volume 48(Issue 12) pp:5187-5194

Publication Date(Web):May 1, 2009

DOI:10.1021/ic9000973

A new N,N′-bidentate ligand, 2-(3-isobutoxyanilino)pyridine (HiBuOap), was introduced and used as the ancillary ligand to support highly soluble diruthenium compounds. Thus, the new compounds Ru2(iBuOap)4Cl (1), Ru2(iBuOap)4(C≡CPh) (2), Ru2(iBuOap)4(C≡CPh)2 (3), and Ru2(iBuOap)4(C≡CSiiPr3) (4) were prepared and characterized by both voltammetric and spectroscopic methods, and their physical properties were found to be quite similar to those of the previously reported Ru2(ap)4-based compounds. The spectroscopic properties of both anionic and cationic derivatives of compounds 2 and 3 were examined with spectroelectrochemistry. Density functional theory calculations performed on model compounds of 2 and 3 provide an in-depth picture of the electronic structures of Ru2(ap)4-based alkynyl compounds and assignment of the observed electronic transitions.

Density Functional Theory Studies of Structural Deformation in Bis(alkynyl)diruthenium(III): Stronger Ru−Ru Bonding by Any Means Necessary

Co-reporter:Isiah Po-Chun Liu and Tong Ren

Inorganic Chemistry 2009 Volume 48(Issue 13) pp:5608-5610

Publication Date(Web):May 28, 2009

DOI:10.1021/ic900795d

Conjugated organometallic compounds diruthenium(6+) bis(alkynyl)s exhibit an unusual structure that is severely distorted from a typical D4 paddlewheel geometry. Density functional theory calculations suggest that the distortion is driven by both the need for an enlarged highest occupied molecular orbital−lowest unoccupied molecular orbital gap and stronger Ru−Ru bonding through the formation of partial σ and π bonds.

Aerobic oxygenation of organic sulfides using diruthenium activators

Co-reporter:Han Baek Lee, Tong Ren

Inorganica Chimica Acta 2009 Volume 362(Issue 5) pp:1467-1470

Publication Date(Web):1 April 2009

DOI:10.1016/j.ica.2008.07.005

Diruthenium compounds supported by carboxylate or mixed carboxylate/carbonate bridging ligands were found to be active catalysts for aerobic oxygenation of organic sulfides. Ru2(OAc)3(CO3) (A), Ru2(O2CCF3)3(CO3) (B) and Ru2(OAc)4Cl (C) promote the conversion of organic sulfide to sulfoxide, and subsequently sulfone in an oxygen atmosphere at ca. 90 °C. The order of catalytic activity is A > B ≫ C. Catalytic reactions are operative in a number of 1:1 co-solvent–H2O combinations, and the highest reactivity was found in aqueous media.Diruthenium complexes of mixed carboxylate and carbonate ligands catalyze aerobic oxygenation of organic sulfides.

Preparation and characterization of diruthenium(II,III) compounds containing terminal olefin groups

Co-reporter:Yang Fan, Phillip E. Fanwick, Tong Ren

Polyhedron 2009 28(16) pp: 3654-3658

Publication Date(Web):

DOI:10.1016/j.poly.2009.07.052

Diruthenium Complexes of Axial Ferrocenyl−Polyynyl Ligands: The Cases of C6Fc and C8Fc

Co-reporter:Bin Xi, Guo-Lin Xu, Phillip E. Fanwick and Tong Ren

Organometallics 2009 Volume 28(Issue 7) pp:2338-2341

Publication Date(Web):March 18, 2009

DOI:10.1021/om801227q

Four Ru2(Y-DMBA)4(C2nFc)2 type compounds with n = 3, 4 and Y-DMBA = N,N’-dimethylbenzamidinate, N,N’-dimethyl-3-methoxybenzamidinate were prepared using a weak-base protocol and characterized using voltammetry and single-crystal X-ray diffraction. Structural studies yielded Fc−Fc (edge−edge) separations of 22.0 and 27.1 Å for n = 3, 4, respectively. The potential differences between two Fc oxidation couples were determined via voltammetric studies as 0.24 and 0.22 V for n = 3, 4, respectively, implying the retention of strong interferrocene electronic couplings over extended distances.

Dimer of Diruthenium Compound Bridged by 1,1′-Diethynylferrocene: Ferrocene as a Weak Mediator for Electronic Coupling

Co-reporter:Yang Fan, Isiah Po-Chun Liu, Phillip E. Fanwick and Tong Ren

Organometallics 2009 Volume 28(Issue 13) pp:3959-3962

Publication Date(Web):May 19, 2009

DOI:10.1021/om900257y

The reaction between Ru2(ap)4Cl (ap = 2-anilinopyridinate) and lithiated 1,1′-diethynylferrocene resulted in the expected product 1,1′-[Ru2(ap)4(C≡C)]2Fc (1) and 1-(Me3SiC≡C),1′-[Ru2(ap)4(C≡C)]Fc (2) as a byproduct. X-ray diffraction study of compound 1 revealed an anti arrangement of two Ru2(ap)4(σ-C≡C) fragments around the Fc unit. Cyclic and differential pulse volatmmetric (CV and DPV) measurements indicated that two Ru2 termini in 1 are weakly coupled in the reduced form. Also reported is the MO analysis of coupling mechanism based on the extended Hückel calculation of 1.

Peripheral Covalent Modification of Inorganic and Organometallic Compounds through C−C Bond Formation Reactions

Co-reporter:Tong Ren

Chemical Reviews 2008 Volume 108(Issue 10) pp:4185

Publication Date(Web):September 9, 2008

DOI:10.1021/cr8002592

Diruthenium(II,III) Bis(tetramethyl-1,3-benzenedipropionate) as a Novel Catalyst for tert-Butyl Hydroperoxide Oxygenation

Co-reporter:Julia E. Barker

Inorganic Chemistry 2008 Volume 47(Issue 7) pp:2264-2266

Publication Date(Web):March 14, 2008

DOI:10.1021/ic800035w

The reaction of Ru2(OAc)4Cl with 2.2 equiv of H2esp (esp = α,α,α′,α′-tetramethyl-1,3-benzenedipropionate) resulted in a new compound, Ru2(esp)2Cl (1), that is soluble in organic media. 1 is an active catalyst for the oxygenation of organic sulfides by tert-butyl hydroperoxide (TBHP) in both an acetonitrile solution or neat (solvent-free) conditions. Solvent-free reactions display the quantitative utility of TBHP and hence excellent chemical selectivity for sulfoxide formation.

The Synthesis and Characterization of Ru2(DMBA-X)4Cl2 with X as Br and I

Co-reporter:Weizhong Chen

Journal of Cluster Science 2008 Volume 19( Issue 1) pp:99-108

Publication Date(Web):2008 March

DOI:10.1007/s10876-007-0155-4

New N,N′-dimethylbenzamidine ligands bearing para-Br (HDMBA-Br) and para-I (HDMBA-I) substituents were prepared and crystallographically characterized. The ligand exchange reaction between Ru2(OAc)4Cl and HDMBA-X (X = Br and I) afforded the new Ru2(III) compounds, namely Ru2(DMBA-X)4Cl2, in excellent yields. These new compounds were also characterized with cyclic voltammetric and single crystal X-ray diffraction techniques.

Bis-alkynyl Diruthenium Compounds with Built-in Electronic Asymmetry: Toward an Organometallic Aviram–Ratner Diode

Co-reporter:Jie-Wen Ying Dr.;Antoinette Cordova;Tony Y. Ren;Guo-Lin Xu Dr.

Chemistry - A European Journal 2007 Volume 13(Issue 24) pp:

Publication Date(Web):6 JUL 2007

DOI:10.1002/chem.200700655

Conditions to prepare trans-[Ru₂(dmba)₄(CCAr)₂] from [Ru₂(dmba)₄(NO₃)₂] (DMBA=N,N′-dimethylbenzamidinate) and HCCAr were optimized; Et₂NH was found to be the most effective among a number of weak bases in facilitating the product formation. Furthermore, a series of unsymmetric trans-[(ArCC)Ru₂(dmba)₄(CCAr′)] compounds were prepared under optimized conditions, in which one or both of Ar and Ar′ are donor (NMe₂)-/acceptor (NO₂)-substituted phenyls. While the X-ray crystallographic studies revealed a minimal structural effect upon donor/acceptor substitution, voltammetric measurements indicated a significant influence of substituents on the energy level of frontier orbitals. In particular, placing a donor and an acceptor on the opposite ends of trans-[(ArCC)Ru₂(dmba)₄(CCAr′)] moiety results in an energetic alignment of frontier orbitals that favors a directional electron flow, a necessary condition for unimolecular rectification.

Negishi Coupling—Expedient Formation of Biphenyls on the Periphery of Inorganic/Organometallic Diruthenium Species

Co-reporter:Lei Zhang, Zhihong Huang, Wei-Zhong Chen, Ei-ichi Negishi, Phillip E. Fanwick, James B. Updegraff, John D. Protasiewicz and Tong Ren

Organometallics 2007 Volume 26(Issue 26) pp:6526-6528

Publication Date(Web):November 29, 2007

DOI:10.1021/om701083q

Negishi coupling is a facile, mild, and high-yield alternative to Suzuki coupling in the biphenyl formation at the periphery of diruthenium coordination and organometallic compounds.

Dimerization of Diruthenium Coordination Compounds via Olefin Metathesis

Co-reporter:Wei-Zhong Chen;John D. Protasiewicz;Ama J. Shirar and

European Journal of Inorganic Chemistry 2006 Volume 2006(Issue 23) pp:

Publication Date(Web):23 OCT 2006

DOI:10.1002/ejic.200600831

Diruthenium compounds containing an ω-alkene-α-carboxylate ligand, Ru₂Cl[D(3,5-Cl₂Ph) F]₃[O₂C(CH₂)_nCH=CH₂] [n = 1 (1a) and 2 (1b)], were prepared from the reactions between Ru₂Cl[D(3,5-Cl₂Ph)F]₃(O₂CCH₃) [D(3,5-Cl₂Ph)F = N,N′-bis(3,5-dicholorophenyl)formamidinate] and ω-alkene-α-carboxylic acids. Both compounds 1a and 1b undergo olefin cross-metathesis reactions catalyzed by (Cy₃P)₂Cl₂Ru(=CHPh) to afford the dimerized compounds [Ru₂Cl{D(3,5-Cl₂Ph)F}₃]₂[μ-O₂C(CH₂)_nCH=CH(CH₂)_nCO₂] [n = 1 (2a) and 2 (2b)]. Molecular structures of compounds 1a/1b and 2a/2b were established by X-ray diffraction studies, which revealed the formation of trans product only in the case of shorter tether (2a) and a mixture of cis-/trans isomers in the case of longer tether (2b). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Synthesis and structural characterization of several dirhenium(III) compounds

Co-reporter:Michael Q. Dequeant, Phillip E. Fanwick, Tong Ren

Inorganica Chimica Acta 2006 Volume 359(Issue 13) pp:4191-4196

Publication Date(Web):1 October 2006

DOI:10.1016/j.ica.2006.06.044

Reaction between Re2(OAc)4Cl2 and N,N′-dicyclohexylbenzamidine (HDCyBA) under molten conditions yielded Re2(DCyBA)2Cl4 (1); reaction of [Bu4N]2[Re2Cl8] with N,N′-di(3-methoxyphenyl)formamidine (HDmAniF) resulted in Re2(DmAniF)2Cl4 (2); reaction of cis-Re2(OAc)2Cl4 with HDmAniF under reflux conditions resulted in cis-Re2(OAc)2(DmAniF)2Cl2 (3). Reaction between Re2(OAc)4Cl2 and α,α,α′,α′-tetramethyl-1,3-benzenedipropionic acid (H2esp) under reflux conditions led to Re2(esp)2Cl2 (4). Crystallographic studies of compounds 1–4 revealed Re–Re bond lengths of 2.1679(6), 2.1804(5), 2.2468(7), and 2.2304(6) Å, respectively, which are consistent with the presence of Re–Re quadruple bond. Also reported are electrochemical properties of compounds 1–4.Novel dirhenium compounds containing labile groups have been prepared and characterized.

N,N′-Dimethylbenzamidine and derivatives: Preparations, structures, and hydrogen bond networks therein

Co-reporter:Wei-Zhong Chen, Guo-Lin Xu, Conrad G. Jablonski, Tong Ren

Journal of Molecular Structure (12 November 2008) Volume 890(Issues 1–3) pp:

Publication Date(Web):12 November 2008

DOI:10.1016/j.molstruc.2008.03.018

Reported herein are the syntheses of N,N′-dimethylbenzamidine (HDMBA, 1) and its phenyl substituted derivatives HYDMBA with phenyl substituents Y as 3-CH3O (2), and 3-CF3 (3), and the determination of single crystal structures of compounds 1–3. In addition, the crystal structures of the salts of 1 with HBF4 (1a), oxalic acid (1b), terephthalic acid (1c), and 2 with HCl (2d) are also reported. Interesting configurations and H-bonding patterns due to the orientation of two methyl groups were observed.

Novel Heterometallic Fe−Ru2−Fe Arrays via “Complex of Complexes” Approach

Co-reporter:Cai-Feng Wang ; Jing Lin Zuo ; Jie-Wen Ying ; Tong Ren ;Xiao-Zeng You

Inorganic Chemistry () pp:

Publication Date(Web):September 24, 2008

DOI:10.1021/ic8011684

Diruthenium(II,III) tetramidates as a new class of oxygenation catalysts

Co-reporter:Leslie Villalobos, Zhi Cao, Phillip E. Fanwick and Tong Ren

Dalton Transactions 2012 - vol. 41(Issue 2) pp:NaN650-650

Publication Date(Web):2011/11/03

DOI:10.1039/C1DT11530H

Silica supported ruthenium oxide nanoparticulates as efficient catalysts for water oxidation

Co-reporter:Yang Zhang and Tong Ren