Search

The role of sodium acetate in the synthesis of [Au(NHC)Cl] complexes was examined. The use of this base was also investigated for the activation of C-H and S-H bonds by experimental and computational methods. The synthetic use of NaOAc to assemble these complexes is applicable to a wide range of NHCs and proceeds under air, under mild conditions and using technical grade green solvents.

Tri- and hexa-cyanoethyl functionalized 17- (L1) and 42-membered (L2) macrocyclic compounds were obtained by [1 + 1] (for L1) or [2 + 2] (for L2) cyclocondensation of the corresponding dialdehyde and diethylenetriamine, followed by hydrogenation by KBH4 and subsequent cyano-functionalization with acrylonitrile. They react with silver nitrate, leading to the formation of [AgL1](NO3) (1) and of the metal–organic coordination polymers [Ag2(NO3)2L1]n (2) and {[Ag2L2](NO3)2}n (3). The complexes were characterized by elemental analysis, 1H NMR, 13C NMR, IR spectroscopies, and ESI-MS; moreover, L2, 1, 2 and 3 were also characterized by single crystal X-ray diffraction. The metal cation in 1 is pentacoordinated with a N3O2 coordination environment; in 2, the metal cations display N4O2 octahedral and N2O3 square-pyramid coordination and in 3 they are in square-planar N4 sites. In 1, the ligand acts as a pentadentate chelator, and in the other two cases, the ligands behave as octadentate chelators in a 1κ3N:κ2O,2κN,3κN,4κN (in 2) or 1κ3N,2κ3N,3κN,4κN fashion (in 3). The cyanoethyl strands of the ligands are directly involved in the formation of the 2D frameworks of 2 and 3, which in the former polymer can be viewed as a net composed of hexametallic 36-membered macrocyclic rings and in the latter generates extra hexametallic 58-membered cyclic sets that form zig-zag layers. The thermal analytical and electrochemical properties of these silver complexes were also studied.

New cationic diruthenium complexes of the type [(arene)2Ru2(SPh)3]+ , arene being C6H6, p-iPrC6H4Me, C6Me6, C6H5R, where R = (CH2)nOC(O)C6H4-p-O(CH2)6CH3 or (CH2)nOC(O)CH[double bond, length as m-dash]CHC6H4-p-OCH3 and n = 2 or 4, are obtained from the reaction of the corresponding precursor [(arene)RuCl2]2 and thiophenol and isolated as their chloride salts. The complexes have been fully characterised by spectroscopic methods and the solid state structure of [(C6H6)2Ru2(SPh)3]+, crystallised as the hexafluorophosphate salt, has been established by single crystal X-ray diffraction. The complexes are highly cytotoxic against human ovarian cancer cells (cell lines A2780 and A2780cisR), with the IC50 values being in the submicromolar range. In comparison the analogous trishydroxythiophenolato compounds [(arene)2Ru2(S-p-C6H4OH)3]Cl (IC50 values around 100 μM) are much less cytotoxic. Thus, it would appear that the increased antiproliferative effect of the arene ruthenium complexes is due to the presence of the phenyl or toluyl substituents at the three thiolato bridges.

Group 4 metal complexes [M(eta(5)-C(5)Me(4)SiMe(2)-eta(1)-N-2R)(NMe(2))(2)] (R = pyridine, pyrazine, pyrimidine, thiazole, M = Ti; R = pyridine, thiazole; M = Zr) containing the tetramethylcyclopentadienyl-dialkylsilyl bridged amidinato as pendant ligand, were synthesized and characterized by elemental analysis, solution (1)H, (13)C and (15)N NMR spectroscopy and experimental (13)C and (15)N CPMAS in the solid state. The crystal structures of [Ti(eta(5)-C(5)Me(4)SiMe(2)-eta(1)-N-2R)(NMe(2))(2)] (R = pyridine, pyrazine, pyrimidine, thiazole) were determined by single crystal X-ray diffraction studies. All compounds exhibit a distorted tetrahedral geometry, with the ansa-monocyclopentadienyl-amido ligands acting in a bidentate mode. The [M(eta(5)-C(5)Me(4)SiMe(2)-eta(1)-N-2R)(NMe(2))(2)] (R = pyridine, thiazole; M = Zr, Ti) complexes are ethylene polymerization catalysts in the presence of MAO and they are active precursors in regioselective catalytic hydroamination operating with an anti-Markovnikov mechanism.