Synthesis and characterisation of cobalt(III), nickel(II), copper(I) and silver(I) complexes of silylated pyridine-2-thione

The electrochemical oxidation of anodic metal (cobalt, nickel, copper and silver) in acetonitrile solutions of the appropriate heterocyclic thione, RMe2SipySH (3-ButMe2SipySH, 3-ThexMe2SipySH, 6-ThexMe2SipySH) gave complexes of general formula [M(RMe2SipyS)] (M = Cu, Ag) and [M(RMe2SipyS)n] (when M = Co, n = 3; M = Ni, n = 2). When the oxidation was repeated in the presence of 2,2′-bipyridine (bipy), the mixed complexes [M(RMe2SipyS)2(bipy)] were obtained only in the case of M = Ni. The reaction between copper complexes, [M(RMe2SipyS)], and 1,2-bis(diphenylphosphino)ethane (dppe) and bis(diphenylphosphino)methane (dppm) in acetonitrile yielded [Cu2(RMe2SipyS)2(dppe)3] and [Cu2(RMe2SipyS)2(dppm)2]. The molecular structures of [Cu6(3-ButMe2SipyS)6], 1, [Cu6(6-ThexMe2SipyS)6], 2, and [3-ButMe2SipyS-Spy-3-ButSiMe2], 3, were determined by X-ray diffraction. Compounds 1 and 2 are hexanuclear with the six copper atoms arranged in a distorted octahedral geometry and each copper atom in a distorted trigonal planar [CuS2N] environment, each ligand adopting the N,S-bidentate S-bridging mode. The electronic, vibrational and 1H and 13C NMR spectra of the complexes are discussed and related to the structure.