Two chiral bisferrocenyl-modified bis(acyl-thiourea) enantiomers, (1R,2R)-bis(ferrocenylcarbonylthioureido)cyclohexane (1) and (1S,2S)-bis(ferrocenylcarbonylthioureido)cyclohexane (2), were synthesized by the reactions of 2.2 equivalents of ferrocenoyl isothiocyanate with (1R,2R) and (1S,2S)-1,2-diaminocyclohexane (1,2-DACH) via a nucleophilic addition reaction, respectively. The two new compounds were fully characterized by 1H NMR, 13C NMR, IR, UV-Vis, elemental analyses and single-crystal X-ray diffraction. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) experiments of compounds 1 and 2 showed roughly similar single reversible redox waves when using nBu4NClO4 (TBAP) as the supporting electrolyte, whereas two CV and DPV waves were observed when using nBu4NBArF4 [ArF4 = 3,5-bis(trifluoromethyl)phenyl]. Furthermore, both compounds 1 and 2 displayed potential antitumor activity against human HepG2 cells. When compounds 1 and 2 were crystallized from diethyl ether, the solvent-free enantiomers (1 and 2) were obtained, respectively. Molecules of both solvent-free enantiomers (1 and 2) assemble into a three-dimensional network structure through hydrogen-bonding and C–H⋯π (cyclopentadienyl rings) interactions. On the other hand, crystallization of compound 1 from benzene produced a benzene disolvate, 1·(C6H6)2. Molecules of the solvent-free and disolvated forms of compound 1 exhibit different molecular conformations and packing arrangements.

The reactions of 2-pyridinecarboxaldehyde-phenylhydrazonatolithium C5H4Npy–CHNi–NaLi(Ph) (abbreviated as LiL) with a 1/2 equivalent of anhydrous metal (Zn, Sn, Fe and Co) chlorides or NiCl2(DME) (DME = 1, 2-dimethoxyethane) produced the corresponding mononuclear metal(II) complexes (1–4 and 7), in which each ligand acts as a bidentate ligand and the coordination geometries around the metals are shown to be tetrahedral within the complexes 1, 3, 4 and 7, respectively, and a tetragonal pyramid in the complex 2. The reaction of LiL successively with sodium tert-butoxide and anhydrous ZrCl4 afforded the unanticipated bizirconium complex 5, in which each monoanionic ligand behaves as a tridentate bridge. Whereas treatment of LiL with NiCl2 and then CH2Cl2 led to an interesting methylene-bridged bis(2-pyridyl-phenylhydrazone) compound 6 in moderate yield; a comparative experiment showed that when the LiL reacted with CH2Cl2, the coupling compound 6 was also obtained but in very low yield. A plausible mechanism of compound 6 formation was also proposed and supported by the density functional theory (DFT) calculations. All the synthesized compounds 1–7 were characterized by single-crystal X-ray diffraction.

The trichlorozirconium η2-hydrazonides (R=H, A; R=CH3, B) were synthesized through the finely controlled stoichiometrical reactions of anhydrous zirconium tetrachloride with the lithium salt of either 1-(furan-2-ylmethylene)-2-phenylhydrazonide or 1-(furan-2-ylethylidene)-2-phenyl hydrazonide in the solvent tetrahydrofuran (THF), respectively. These complexes were highly sensitive to air and moisture due to solely using less bulky ligand of hydrazonides. The molecular structures of the title complexes, determined by means of single crystal X-ray diffraction, were found to be the distorted pentagonal bipyramid geometry around zirconium atom, with three chlorides and the hydrazonato ligand acting as the η2-coordination mode as well as two incorporated THF molecules. Upon activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), both complexes A and B exhibited catalytic activities toward ethylene polymerization, producing polyethylenes with ultra-high molecular weights.

•A new compound, 2-quinolinone derivative was designed, synthesized and characterized.•Its selective recognition ability on Hg2+ was firstly studied by fluorescence and UV–vis spectroscopies.•The detection mechanism was explored by ESI-MS and 1H NMR analysis.A new compound based on 2-quinolinone derivative with very little side effects on organisms, 3-(1H-benzo[d]imidazol-2-yl)-6,7-difluoroquinolin-2(1H)-one, has been designed, synthesized and characterized. And its recognition ability was firstly studied by spectroscopy. The result indicated that the compound shows high selectivity for Hg2+ over other metal ions with detectable fluorescent signals in aqueous-methanol media. The proposed mechanism is that the fluorescence of the probe was quenched due to the effect from spin–orbit coupling of Hg2+ after the probe coordinated with Hg2+, and was proved by ESI-MS and 1H NMR analysis.Graphical abstract

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.

The tBu-ended ansa-bis(amidine) SiMe2[NC(Ph)NH(tBu)]2 (1) was prepared by treating tBuNH2 with one equivalent of both LiBun and PhCN, and half equivalent of SiMe2Cl2 in a one-pot reaction. 1 combined with HCl to give an ion pair complex [(tBu)NHC(Ph)NH]SiMe2[NC(Ph)NH(tBu)]Cl (2) and one N–C–N moiety was converted to a cationic amidinium ion. The complexation behaviour of 1 with group IV metal chlorides was explored. Treating 1 with TiCl4(thf)2 in CH2Cl2 gave the titanium complex [(tBu)NHC(Ph)N]Ti(thf)2Cl3 (3), in which the mono-amidinato ligand was supposedly derived from N–Si cleavage of 1 due to the high Lewis acidity of the titanium salt. The zirconium complex [(tBu)NHC(Ph)NH]SiMe2[NC(Ph)N(tBu)]ZrCl4 (4) and the hafnium complex 5 were obtained by treating 1 with MCl4 (M = Zr and Hf) in THF and these complexes were crystallized from CH2Cl2. Reaction of 1 with TiCl4(thf)2 in toluene yielded {SiMe2[NC(Ph)NH(tBu)]2Ti[NC(Ph)NH2(tBu)]Cl3}Cl (6), indicating the N–Si cleavage could be partially suppressed in a less polar environment. Recrystallization of 4 in toluene afforded SiMe2[NC(Ph)NH(tBu)]2ZrCl4 (7). Similarly, recrystallization of 5 in toluene gave 8, which is isostructural to 7. The reaction of 4 with AlMe3 in THF yielded the zirconium complex [(tBu)NHC(Ph)N]Zr(thf)2Cl3 (9), which is analogous to 3. The solid state structures of complexes 2, 3, 4, 6, 7, 8 and 9 were investigated by single crystal X-ray structural analysis. Complexes 3 and 9 were found to be moderately active towards ethylene polymerization in the presence of methylaluminoxane (MAO).Diverse complexation modes could be observed in group IV complexes supported by tBu-ended ansa-bis(amidine) SiMe2[N(H)C(Ph)N(tBu)]2. Two different forms were crystallized from dichloromethane and toluene, respectively. The transformation was driven by the different polarity of the solvents. With methylaluminoxane, some complexes were active in catalyzing ethylene polymerization.

Addition reactions of lithium bis(trimethylsilyl)amide with dimethylcyanamide lead to novel lithium salts of 6-((trimethylsilyl)amido)-2,4-bis(dimethylamino)[1,3,5]triazines [LLi(D)]2 (L = NC(NMe2)NC(NMe2)NC(NSiMe3); D = Me2NCN (1), Et2O (2)) and to the Mn and Co complexes [LL′M] (L′ = N{N(SiMe3)C(NMe2)}2; M = Mn (3), Co (4)); the structures of crystalline 1, 3, and 4 are reported. Their formation involves trimethylsilyl shifts, ring formation, and unusual Me2NSiMe3 elimination.

Lithium N-[(N,N-dimethylamino)dimethylsilyl]-2-pyridylamidate (2) was prepared from the reaction of new compound N-[(N,N-dimethylamino)dimethylsilyl]-2-pyridylamine (1) and LiBun. Treatment of the lithium salt (2) with an equal equivalent of MgBr2(THF)2, FeCl2 and CoCl2 afforded the corresponding dinuclear complexes 3, 4, and 5, in which metal atoms possess similar trigonal bipyramidal geometries and each ligand functions as a bimetallic bridging binding aminopyridinato moiety with N-donation from the dimethylamino group. While the stoichiometric reaction of 2 with ZrCl4 gave the mononuclear zirconium complex (6); the seven coordinated zirconium atom adopts a distorted pentagonal bipyramid geometry and the ligand acts as monoanionic η2-aminopyridinato moiety with the pendant arm coordinated via N(CH3)2. The reaction of 2 with one equivalent of TiCl4(THF)2 produced the interesting dinuclear titanium complex (7) owing to the elimination of a (N,N-dimethylamino)dimethylsilyl group from the original ligand, and the two titanium centers present different coordination geometries. The molecular structures of the crystalline metal complexes 3–7 have been confirmed by X-ray single crystal diffraction analysis. Upon activation with methylaluminoxane (MAO), both complexes 6 and 7 exhibited moderate catalytic activities toward ethylene polymerization and produced high molecular weight polyethylenes with broad molecular weight distributions.

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.

The mononuclear silyl-linked bis(amidinate) titanium compound 2 was prepared by salt metathesis of 1 and TiCl4(thf)2. Alkylation of 2 with methyllithium gave analogue 3. Both 2 and 3 exhibited a configuration similar to ansa-metallocene and showed good activity towards ethylene polymerization after activation with MAO.

Two ferrocene-modified pyrimidinyl acyl-thiourea derivatives, N-ferrocenoyl-N′-(2-pyrimidinyl) thiourea 1 and N-ferrocenoyl-N′-(5-pyrimidinyl) thiourea 2 were prepared from the reactions of ferrocenoyl isothiocyanate with 2-aminopyrimidine or 5-aminopyrimidine, respectively. Both of the new compounds were characterized by 1H NMR, 13C NMR, IR, elemental analyses and single-crystal X-ray diffraction. Comparing with ferrocene, compounds 1 and 2 show red-shift in the absorption peaks and increasing anodic peak potentials (Epa) values in the cyclic voltammetry studies. Furthermore, the electrochemical data of compounds 1 and 2 correspondingly exhibit one-electron quasi-reversible and reversible electrochemical redox behaviors. In the solid-state, compound 1 forms a ladder-like assembly by hydrogen-bonding, whereas, compound 2 is assembled into two-dimensional network structure through hydrogen-bonding and unusual intermolecular O⋯π interactions between O-atoms of the carbonyl units and the cyclopentadienyl rings.Highlights► Synthesis of two new ferrocene-modified pyrimidinyl acyl-thiourea derivatives. ► Unusual intermolecular CO⋯π (cyclopentadienyl ring) interaction. ► UV–Vis spectroscopy and cyclic voltammetry studies.

The dimer of lithium μ2,η1-N-[(N,N-dimethylamino)dimethylsilyl]-2,6-diisopropylanilidate [1c, [LiN(2,6-iPr2C6H3)Si(CH3)2N(CH3)2]2 represented as (LiL)2] reacted with group 4 chlorides to form corresponding compounds, which were crystallized and confirmed by X-ray diffraction analysis as compounds of pseudotetrahedral ZrL2Cl2 (2) and chloro-bridged dinuclear tetrahedral compounds ZrLCl2(μ-Cl)2Li·2THF (3), ZrLCl2(μ-Cl)2Li·2Et2O (4), HfLCl2(μ-Cl)2Li·2Et2O (5), and [ZrLCl2(μ-Cl)]2 (6). The catalytic behaviors of group 4 compounds were investigated in the presence of MAO as a cocatalyst. Compound 4 exhibited high activity for ethylene polymerization, while compounds 2 and 6 showed good activities for both ethylene polymerization and ethylene/1-hexene copolymerization.

(2,6-Diisopropyl-N-(1-phenylvinyl)benzenamido)magnesium bromide (CH2(Ph)C(2,6-iPr2C6H3)NMgBr·2THF, 1b) reacted with 1 equiv of Me2NMe2SiCl to form the N-(2-((dimethylamino)dimethylsilyl)-1-phenylvinyl)-2,6-diisopropylbenzenamine (1c). The stoichiometric reaction of 1c with lithium diisopropylamide (LDA) formed lithium N-(2-((dimethylamino)dimethylsilyl)-1-phenylvinyl)-2,6-diisopropylbenzenamidate (Me2NMe2SiCH(Ph)C(2,6-iPr2C6H3)NLi·3THF, 1d) in high yields. The reaction of zirconium tetrachloride with 2 equiv of 1d produced the bisligated (η3-azaallyl)zirconium dichloride ((η3-(2,6-iPr2C6H3)N(Ph)CCHSiMe2NMe2)2ZrCl2, 2), whereas the stoichiometric reaction of zirconium tetrachloride with 1d formed a monoligated zirconium trichloride complex ((η3:η1-(2,6-iPr2C6H3)N(Ph)CCHSiMe2NMe2)ZrCl3, 3), in which the ligand acted as an η3-azaallyl species with N-donation via the dimethylamino group at the silyl bridge. All compounds were fully characterized by elemental and spectroscopic analyses and metal compounds by single-crystal X-ray diffraction. The azaallyl groups of the ligands act in a κ1-enamido fashion in compounds 1b,d, while the azaallyls appear as an η3-N,C,C mode in compound 2. The η3:η1 coordination of the azaallyl and dimethylsilyl groups provided a sterically constrained geometry around the zirconium in compound 3. The coordination geometries around each zirconium are pseudo-octahedral in both compounds 2 and 3. The modes of coordination affected their catalytic behaviors toward polymerization: high activity by 3 and good activity by 2.

2,4-N,N′-Disubstituted 1,3,5-triazapentadienyl ligands as their lithium salts [Li{(N(R)C(R′))2N}]2 [where R = SiMe3 here and hereafter and R′ = dimethylamino (1) or 1-piperidino (2)] were synthesized via the reactions of LiN(SiMe3)2 with 2 equiv of the α-hydrogen-free carbonitrile dimethylcyanamide or 1-piperdinecarbonitrile and used in the isolation of the two-coordinate copper(I) complexes [Cu{(N(R)C(R′))2N}]2 [R′ = dimethylamino (3) and 1-piperidino (4)]. Complex 2 features a twisted W-shaped ligand backbone in the solid state. Complexes 3 and 4 show an unusual 12-membered ring dinuclear copper(I) triazapentadienyl and a less expressed ability to form a stable delocalized triazapentadienyl system.

The promotional effects of ZrO2 on Ni/ZrO2–SiO2 catalysts were investigated by the comparison of Ni/SiO2 and Ni/ZrO2–SiO2 activity in the hydrogenation of maleic anhydride (MA) to γ-butyrolactone (GBL), and by the measurements of X-ray diffraction (XRD), Fourier transform infrared (FT-IR), temperature-programmed reduction (TPR) and ammonia temperature-programmed desorption (NH3-TPD). The presence of ZrO2 led to an obvious increase of GBL yield. The promotion effect could be attributed to the possible presence of Zr4+ species on the catalyst surface owing to the higher ionicity of the Zr–O bonds, and to the proper interaction of Ni with the ZrO2-SiO2 support that is regulated by the presence of ZrO2.

A novel type of linked bis(amidinate) ligands (D) were developed successfully. Their lithium derivatives 1–4 were synthesized by treating the silyl-bridged diamines I–IV with two equivalents of LiBun and PhCN in sequence, which underwent a silyl-bridge migration process. In addition, the linked bis(amidinate) configuration proved to be the thermodynamically stable form rather than the mono(amidinate) type by contrasting reaction of I with one equivalent of LiBun and PhCN in sequence.

A series of mesoporous SiO2ZrO2 aerogels with various zirconia content (10–90 wt%) were prepared by the sol–gel method followed by supercritical drying. The characterization of aerogels is performed by XRD, FT-IR, 29Si liquid-state NMR, and BET-N2 adsorption. The results showed that (i) the aerogels have type VI (BDDT) profile which is the typical of mesopores in the interval between 2