The syntheses and crystal structures of a series of heterobimetallic Li/Mg and Li/Al complexes prepared from an N,N,O-tridentate ligand are described. The ligand HOC(CH2)5CH2N(Me)CH2CH2NMe2 (LH) and nBu2Mg were used to synthesize the homometallic magnesium alkoxide [{LMgOC(CH2)5CH2N(Me)CH2CH2NMe2}2] (1), which was reacted with nBuLi to afford the lithium alkylmagnesiate [{Bu2Mg{LiOC(CH2)5CH2N(Me)CH2CH2NMe2}}2] (2). Complex 2 was then hydrolyzed to produce [{BuMgOLi{LiOC(CH2)5CH2N(Me)CH2CH2NMe2}2}2] (3). The sequential reaction of LH in diethyl ether with RAlMe2 (R = Me, Cl) and nBuLi aforded two lithium aluminate complexes containing a polymeric structure of one-dimensional chains [{−LiOC(CH2)5CH2N(Me)CH2CH2NMe2}Al(Me)(n-Bu)CH3−}n] (4) and [{−LiOC(CH2)5CH2N(Me)CH2CH2NMe2}Al(n-Bu)2CH2−}n] (5), respectively. Each of the complexes 1–5 was structurally characterized and tested for its capability to catalyze Meerwein–Ponndorf–Verley (MPV) reactions. Heterobimetallic complexes 2 and 3 exhibited catalytic activities better than those of homometallic magnesium complex 1 and heterobimetallic lithium aluminate complexes 4 and 5 for MPV reactions.

Lithium complex stabilised by 2-amino-functionalized benzoylpyrrole was synthesized, and its structural features were provided. The molecular structure shows a novel tetrameric cage structure, which includes a eight-membered (LiN)4 ring and a eight-membered (LiO)4 ring with the coordinating pyrrolyl ligands. It was proved to an efficient catalyst for the cyclotrimerisation of isocyanates in good to excellent yields under mild conditions.Lithium complex stabilised by 2-amino-functionalized benzoylpyrrole was synthesized, and its structural features were provided. The molecular structure shows a novel tetrameric cage structure, which includes a eight-membered (LiN)4 ring and a eight-membered (LiO)4 ring with the coordinating pyrrolyl ligands. It was proved to an efficient catalyst for the cyclotrimerisation of isocyanates in good to excellent yields under mild conditions.Download high-res image (50KB)Download full-size image

The exploration of co-complexation reactions between alkai-metal reagents and ZnEt2 with bidentate aminopyrrolyl ligands afforded a series of alkali-metal (Li, Na, K) alkyl zincates with a variety of intriguing structures, ranging from molecular complexes to more coordination polymers. All aforementioned complexes have been characterized by X-ray crystallography, NMR, IR and UV-vis spectroscopy.

•We designed a special one dimensional metal-dielectric photo band gap materials (1D-MD PBG) which consisting of discontinuous metal films. However, 1D-MD PBG in previous studied is often composited by continuous metal films.•The designed 1D-MD PBG have a high electrical conductivity (the sheet resistivity can be lower than 0.98 Ω/square) due to high local field enhancement. The finding is contrast to the common sense.•We found that both the light transmittance and electrical conductivity could be significantly improved by using of (pqp)N structure, whose electrical conductivity has rarely discussed.•The relation of location and bandwidth of transmission with respect of the structure of 1D-MD PBG is revealed in the paper.•We found a suitable ratio of Ag and ITO thicknesses which gives a good transmission at a range from green to blue (450 nm–550 nm).The paper shows the determination of the transmission of one dimensional metal-dielectric photonic band gap materials (1D-MD PBG) theoretically and experimentally. It has been found that the location and bandwidth of transmission can be tailored by initiatively adopting a suitable structure. We proposed a special 1D-MD PBG obtained by magnetron sputtering, in which each layer of metal film is not continuous. These structures have a number of advantages such as high transmittance (55% or better), broad bandwidth (the full width at half of maximum ranges from 400 nm to 780 nm) and high electrical conductivity (the sheet resistance can be lower than 0.98 Ω/square). Meanwhile, it has been also theoretically and experimental indicated that both the light transmittance and electrical conductivity could be improved effectively by using the (pqp)N structure.

•A series of aluminum complexes of β-hydroxy-imino ligands were synthesized.•Their structures were characterized by NMR, elemental analysis and X-ray study.•Those compounds as catalysts for Tishchenko reaction have been investigated.Four aluminum alkoxide complexes containing β-hydroxy-imino ligands, [(2,6-Me2C6H3)NCPhCH2CPh2O]2AlMe (3a), [(2,6-iPr2C6H3)NCPhCH2CPh2O]2AlMe (3b), [(2,6-Me2C6H3)NCPhCH2C(C12H8)OAlMe2]2 (3c) and [(2,6-iPr2C6H3)NCPhCH2C(C12H8)OAlMe2]2 (3d) were synthesized in high yields, and their structural features were provided. The catalytic behavior of those four complexes about the Tishchenko reaction with a range of aromatic aldehydes as substrates were assessed, and it present a synthetically useful protocol to the solvent-free Tishchenko reaction under mild conditions.

•Insertion of CO2 into the Li–N bond of amidinolithium compound has been studied.•Two amidinolithium compounds were characterized by NMR, elemental analysis and X-ray study.•They show a novel cage structure and a “wheel” cage structure, respectively.Insertion of CO2 into the Li–N bond of two amidinolithium compounds [{LiN(2,6-Me2C6H3)C(H)N(2,6- Me2C6H3)}2(THF)3] and [{LiN(4-CH3C6H4)C(H)N(4-CH3C6H4)}2(THF)3] have been studied, and two lithium carbamate compounds [Li{O2C(N(2,6-Me2C6H3)C(H)N(2,6-Me2C6H3))}·THF]4 (1) and [Li{O2C(N(4-CH3C6H4)C(H)N(4-CH3C6H4))}·THF]6 (2) were obtained. The molecular structure of 1 shows a novel cage structure containing four eight-membered (LiOCOLiOCO) rings and two four-membered (LiOLiO) rings with the [Li4(CO2)4]4+ cluster in central. And an unusual and novel structure of 2 was obtained with a “wheel” cage structure including six six-membered (LiOLiOCO) rings surrounding the [Li6(CO2)6]6+ cluster. Both of 1 and 2 were fully characterized by elemental analysis, NMR spectroscopy, and X-ray structural determinations.

Deprotonation of HOC(CH2)5CH2C6H4–NMe2-2 (L1H) and HOC(CH2)5C6H4–NMe2-2 (L2H) by equivalent of n-BuLi afforded the pale yellow mixture L1Li or L2Li, which reacted with MgBr2 in different molar ratios to give three novel bidentate N, O-magnesium complexes (1), (2) and (3), respectively. Complexes 1–3 were characterized by 1H and 13C NMR spectroscopy, elemental analyses and single crystal X-ray diffraction techniques. Each of the complexes 1, 2 and 3 was tested for the capability of catalyzing transfer hydrogenation of ketones. Complex 1 exhibited good to excellent catalytic activity, while complexes 2 and 3 showed good activities for the transfer hydrogenation of ketones.Deprotonation of HOC(CH2)5CH2C6H4–NMe2-2 (L1H) and HOC(CH2)5C6H4–NMe2-2 (L2H) by equivalent of n-BuLi afforded the pale yellow mixture L1Li or L2Li, which reacted with MgBr2 in different molar ratios to give three novel bidentate N, O-magnesium complexes (1), (2) and (3), respectively. Complexes 1–3 were characterized by 1H and 13C NMR spectroscopy, elemental analyses and single crystal X-ray diffraction techniques. Each of the complexes 1, 2 and 3 was tested for the capability of catalyzing transfer hydrogenation of ketones. Complex 1 exhibited good to excellent catalytic activity, while complexes 2 and 3 showed good activities for the transfer hydrogenation of ketones.

•A simple and efficient catalytic system for Tishchenko reaction is presented.•The redox reaction between aminopyrrolyl lithium and aldehyde was reported firstly.•The initiated intermediate was characterized by NMR, elemental analysis and X-ray study.The dimerization of aldehydes to the analogous carboxylic esters (Tischenko reaction) has been achieved in impressive yields using the dilithium compounds containing bidentate di-anionic pyrrolyl ligands as initiators. The initiated intermediate {[2-(tBuNCH)C4H3NLi][PhCH2OLi(TMEDA)]}2 was isolated and characterized by satisfactory C, H and N microanalysis, 1H, 13C{1H} and 7Li NMR spectra in pyridine-d5 at ambient temperature, and single crystal X-ray structural data. The processes involve a redox reaction of 2-aminopyrrolyl dilithium compound with aldehyde.The dimerization of aldehydes (Tischenko reaction) has been achieved in impressive yields using 2-aminopyrrolyl dilithium compounds as initiators. The initiated intermediate {[2-(tBuNCH)C4H3NLi][PhCH2OLi(TMEDA)]}2 was isolated and characterized by microanalysis, NMR spectra and single crystal X-ray structural data. The processes involve a redox reaction of 2-aminopyrrolyl dilithium compound with aldehyde.

A direct transition-metal-free synthesis of 2-benzoylpyrrole derivatives from free (N–H) pyrroles and benzaldehyde has been developed. The benzoylation reaction at the 2 or 5-position of pyrrole proceeded well under the alkali metalation system and with 2,6-dimethylaniline as the additive in moderate to good yields. This strategy offers a simple, efficient approach to synthesis of the 2-benzoylpyrrole derivatives.A direct transition-metal-free synthesis of 2-benzoylpyrrole derivatives from free (N–H) pyrroles and benzaldehyde has been developed. This strategy offers a simple, efficient approach to synthesis of the 2-benzoylpyrrole derivatives.

•A series of tridentate pyrrolylzinc compounds were synthesized.•Their structures were characterized by NMR, elemental analysis and X-ray study.•Those compounds as catalysts for cyclotrimerization of isocyanates have been investigated.The reactions of ZnEt2 with NNN-tridentate pincer type pyrrolyl ligands, 2,5-bis((dimethylamino)methylene)-1H-pyrrole (HL1), 2,5-bis((pyrrolidin-1-yl)methylene)-1H-pyrrole (HL2) and 2,5-bis((piperidino)methylene)-1H-pyrrole (HL3), afford zinc ethyl compounds [C4H2N(2,5-CH2NMe2)2]ZnC2H5 (1), [C4H2N(2,5-CH2N(CH2)4)2]ZnC2H5 (2), and [C4H2N(2,5-CH2N(CH2)5)2]ZnC2H5 (3) in high yield. Subjecting 1, 2, 3 with one equivalent of tert-butylphenol in THF generated {[C4H2N(2,5-CH2NMe2)2]Zn(O–C6H4-4-tBu)}2 (4), {[C4H2N(2,5-CH2N(CH2)4)2]Zn(O–C6H4-4-tBu)}2 (5), {[C4H2N(2,5-CH2N(CH2)5)2]Zn(O–C6H4-4-tBu)}2 (6), respectively. Each has been characterized by satisfactory C, H and N microanalysis, NMR spectroscopy at ambient temperature, and single crystal X-ray structural analysis. The compounds Et6Zn6O2[C4H2N(2,5-CH2N(CH2)4)2]2 (7) and Et6Zn6O2[C4H2N(2,5-CH2N(CH2)5)2]2 (8) obtained accidentally from zinc ethyl compounds with traces of water. Each of compound 1–6 has been used as initiator for cyclotrimerization of isocyanate, and the organozinc compound 3 shows moderate reactivity toward the cyclotrimerization of isocyanate in Et2O solvent under mild conditions.A series of zinc complexes containing monoanionic tridentate pyrrolyl ligands have been prepared in good yield and characterized by microanalysis, multinuclear NMR ambient temperature solution spectra and X-ray molecular structures. Each of the complexes exhibited moderate to good catalytic activity for cyclotrimerization of isocyanates under mild condition.

Deprotonolysis of the N,O-bidentate pyridyl functionalized alkoxy ligands, 1,1-dimethyl-2-(pyridin-2-yl)ethanol (L1H), 1-phenyl-2-(pyridin-2-yl)ethanol (L2H) and 1,1-diphenyl-2-(pyridin-2-yl)ethanol (L3H), with 1 equiv of AlMe3 gave the corresponding dimeric metal-monoalkyl compounds [L1AlMe2]2 (1), [L2AlMe2]2 (2), and [L3AlMe2]2 (3), respectively. Compounds 1–3 were characterized by 1H and 13C NMR spectroscopy analysis, and the molecular structures of 1 and 2 were further confirmed by X-ray diffraction analysis. In the presence of iPrOH, aluminum compounds 1–2 exhibited excellent catalytic activity for the solvent-free Tishchenko reaction under mild conditions. In addition, the catalyst 3 can be easily isolated and recycled three times without a significant decrease in activity.

Lithium, magnesium, zinc complexes incorporating substituted symmetrical tridentate pyrrolyl ligands were synthesized conveniently and their application for the cyclotrimerization of isocyanate to corresponding isocyanurate has been investigated. The reaction of 1 equivalent of 2,5-bis(pyrrolidinomethyl)pyrrole {C4H2NH(2,5-CH2NC4H8)2} with n-BuLi generated [Li{C4H2N(2,5-CH2NC4H8)2}]2 (1) in diethyl ether. Treatment of 2 equivalents of C4H2NH(2,5-CH2NC4H8)2 with MgBu2 or ZnEt2 in THF afforded [Mg(THF){C4H2N(2,5-CH2NC4H8)2}2] (2) or [Zn{C4H2N(2,5-CH2NC4H8)2}2] (3) in high yield, respectively. Compounds 1, 2 and 3 were characterized by 1H and 13C NMR spectra and their molecular structures were determined by single crystal X-ray diffraction. Furthermore, compounds 1, 2 and 3 were proved to be moderate to good initiators for cyclotrimerization of isocyanate to the corresponding isocyanurate in diethyl ether.A convenient and practical method for the cyclotrimerization of isocyanates is described. The reaction was catalyzed in the presence of catalytic amounts (1.0 mol%) of lithium, magnesium, zinc complexes incorporating substituted symmetrical tridentate pyrrolyl ligands leads to the corresponding isocyanurates in good yields. The best result was obtained when the lithium compound was employed as initiator.

•Three bidentate pyrrolyl lithium complexes were synthesized and characterized.•The title complexes for cyclotrimerization of isocyanates have been investigated.•All title complexes show high catalytic activities on cyclotrimerization of isocyanate.Three bidentate pyrrolyl lithium complexes were synthesized and their application for the cyclotrimerization of isocyanate to corresponding isocyanurate has been investigated and show high catalytic activities. All lithium complexes were characterized by NMR spectroscopy, elemental analysis and X-ray diffraction analysis.A convenient and practical method for the cyclotrimerization of isocyanates is described. The reaction is catalyzed in the presence of catalytic amounts (0.1 mol%) of lithium compounds containing substituted pyrrolyl ligands leads to the corresponding isocyanurates in high yields (up to 98%).

Treatment of a secondary amine (pipH, Bz2NH, Et2NH) with sequentially diethylzinc and N,N′-dicyclohexylcarbodiimide in hexane has afforded in good yield the new crystalline guanidinatozinc complexes. Each has been X-ray and solution NMR spectrally characterized. Three are dimeric (mono)guandinatozinc alkyls, two are dinuclear (tris)guanidinatozinc amides, and one is a homoleptic zinc bis(guanidinate). The reactions of dinuclear (tris)guanidinatozinc amides with diethylzinc and N,N′-dicyclohexylcarbodiimide in the molar ratios of 1:2:1 led to the dimeric (mono)guandinatozinc alkyls; homoleptic zinc bis(guanidinate) with an equimolar portion of diethylzinc also yielded dimeric (mono)guandinatozinc alkyls. Each of the complexes exhibited good to excellent catalytic activity for the solvent-free Tishchenko reaction under mild conditions.

Five dilithium compounds containing bidentate dianionic pyrrolyl ligands, [{2-(CH3NCH2)C4H3N}Li2(TMEDA)3] (1), {[μ-η5-2-[CH3CH2NCH2]C4H3N]Li2(TMEDA)}2 (2), {[μ-η5:η1-2-[(CH3)3CNCH2]C4H3N]Li2(TMEDA)}2 (3), {[η5-2-[(CH3)2CHNCH2]C4H3N]Li2 (TMEDA)}2 (4), and {[η5-2-[(CH2)5CHNCH2]C4H3N]Li2(TMEDA)}2 (5), were synthesized, and their structural features were provided. Compounds 1–5 were proved to be a series of efficient catalysts for amidation reactions of aldehydes with amines in good to excellent yields under mild conditions.

Treatment of [LiL·TMEDA] (1) {L = [2-Me2NCH2C6H4CH(SiMe3)]−} with half equivalent of ZnCl2, CdCl2 or MnCl2 in diethyl ether gave the crystalline compound [ML2] {M = Zn (2), Cd (3) and Mn (4)}, respectively. Reaction of 1 with one equivalent of ZnCl2 in diethyl ether afforded the crystalline compound [Zn(Cl)L·TMEDA] (5) in good yield. An eight-membered cyclic homoleptic binuclear compound [ZnL′]2 (6) {L′ = [(2-Me2NCH2C6H4CH)2SiMe2]2−} was prepared from the reaction of (2-Me2NCH2C6H4CH2)2SiMe2 (B′) with two equivalents of n-BuLi and one equivalent of ZnCl2. All of the crystalline compounds 1–6 were well characterized by 1H NMR, 13C NMR spectroscopy, elemental analyses and single crystal X-ray crystallography. In addition, moderate activity for the polymerization of rac-lactide to poly(lactic acid) (PLA) was found in compounds 2 and 5, and all the resulting polylactides are most predominantly heterotactic-rich.Graphical abstractZn(II), Cd(II) and Mn(II) complexes [ML2] [M = Zn (2), Cd (3), Mn (4)], [LZnCl·TMEDA] (5) and [ZnL′]2 (6) {L = [2-Me2NCH2C6H4CH(SiMe3)]−, L′ = [(2-Me2NCH2C6H4CH)2SiMe2]2−} were prepared from [LiL·TMEDA] (1) and corresponding metal chloride. X-ray structures of 1–6 were reported. Compounds 2 and 5 exhibited moderate activity towards polymerization of rac-lactide.Highlights► Six novel N-functionalized benzyl metal compounds were synthesized and characterized. ► Compounds 2 and 5 exhibited moderate activity towards polymerization of rac-lactide to poly(lactic acid). ► All the resulting polylactides are most predominantly heterotactic-rich.

Methanol-to-diesel (MTD) means a synthetic diesel fuel, its raw material is methanol. And it is a liquid alcohol ether mixture with appropriate amount of additives, which can be blended with diesel fuel at various levels. It was synthesized by methanol with 1,2-epoxypropane and epoxyethane using modified calcined Mg/Al hydroxides as catalysts. The test and study on the physical properties of MTD and the fuel consumption and emissions of diesel engine using the mixed MTD and diesel fuel have been performed. The results indicates that there was no significant difference in the power values of diesel and the blend fuels while fuel consumption increasing around 14%, and of much lower emissions of exhaust. When using the diesel fuel mixed with 20–30% of MTD. The conclusion is that MTD is a cheap and clean low power loss additive fuel for diesel engines.

The reaction of formalin with 2,4-pentanedione yielded a previously unreported compound, 3,5,5,7-tetraacetylnonane-2,8-dione. The molecular structure of this compound was obtained by single-crystal X-ray diffraction. The compound crystallized in the triclinic space group Pī with cell parameters a = 9.033(4) Å, b = 9.525(2) Å, c = 10.477(6) Å, α = 82.62 (5)°, β = 76.11 (3)°, γ = 84.44 (3)°, V = 865.8(6) Å3 and Z = 2. The structure has been solved by direct methods and refined to R1 = 0.0596 for 3,543 observed reflections I > 2σ(I). Details of the synthesis and the structural characterization of the title compound are presented and discussed.

A novel zinc complex diaminebis(phenolate) [zinc 2,2-{μ-(N,N′-dimethylethyleneamino)dimethyl}-bis(4,6-di-tert-butylphenolate)] (LZn) was synthesized, structurally characterized, and its application as an initiator for the ring-opening polymerization of rac-lactide was reported.A novel zinc complex diaminebis(phenolate) [zinc 2,2-{μ-(N-N′-dimethylethyleneamino)dimethyl}-bis(4,6-di-tert-butylphenolate)] (LZn) was synthesized, structurally characterized, and its application as an initiator for the ring-opening polymerization of rac-lactide was reported.

Treatment of a secondary amine (piperidine or N-benzylmethylamine) with sequentially trimethylaluminum and carbodiimide CyNCNCy in a molar ratio of 1:1:1 afforded two mononuclear guanidinatoaluminum complexes, [{(C5H10N)C(NCy)2}AlMe2] (1) and. [{(Bz(Me)N)C(NCy)2}AlMe2] (2). Introducing dry oxygen slowly into the solution of 1 or 2, [{(C5H10N)C(NCy)2}AlMe(μ-OMe)]2 (3) and [{(Bz(Me)N)C(NCy)2}AlMe(μ-OMe)]2 (4) were obtained, respectively. Both of 3 and 4 were also prepared by treatment of piperidine or N-benzylmethylamine with trimethylaluminum and carbodiimide CyNCNCy in the presence of O2. The complexes 1–4 were characterized by 1H, 13C NMR spectra and single crystal X-ray diffraction analysis. 1–4 were also used to catalyze the Meerwein–Ponndorf–Verley (MPV) reaction.The synthesis of four guanidinatoaluminum complexes is described. The molecular structures of four guanidinatoaluminuml complexes were confirmed by a single crystal X-ray diffraction study. In addition, the guanidinatoaluminuml complexes were also used to catalyze the Meerwein–Ponndorf–Verley (MPV) reaction of a series of aromatic and aliphatic aldehydes to the corresponding alcohols.

•Four novel chiral zinc and aluminum complexes have been synthesized.•Their structures were confirmed by X-ray diffraction analyses.•All complexes are active catalysts for the polymerization of rac-lactide.The crystalline complexes L2Zn (1), L3Al (2), L′2Zn (3) and L'AlMe2 (4) were synthesized from the reactions of the corresponding chiral ligands (S)N-(2-pyrrolylmethylene)-1-phenylethylamine (HL) or (S)N-(2-pyrrolylmethyl)-1-phenylethanamine (HL′) and diethylzinc or trimethylaluminum, respectively. Complexes 1–4 were well characterized by 1H NMR, 13C NMR spectroscopy, elemental analyses and single crystal X-ray crystallography. Furthermore, the catalytic activities toward ring-opening polymerization (ROP) of rac-lactide have been investigated and all of the complexes can be used as initiators to give the isotactic-rich polylactides.Four novel chiral zinc and aluminum complexes L2Zn (1), L3Al (2), L′2Zn (3) and L'AlMe2 (4) [L= (S)-2-pyrrolal-1-phenylethylimine, L'= (S)-N-((2-pyrrolyl)methyl)-1-phenylethanamine were synthesized in moderate or good yield via simple synthetic routes and all of the complexes can be used as initiators to give the isotactic-rich polylactides.

The exploration of co-complexation reactions between alkai-metal reagents and ZnEt2 with bidentate aminopyrrolyl ligands afforded a series of alkali-metal (Li, Na, K) alkyl zincates with a variety of intriguing structures, ranging from molecular complexes to more coordination polymers. All aforementioned complexes have been characterized by X-ray crystallography, NMR, IR and UV-vis spectroscopy.