COPPER(I) COMPLEXES OF STERICALLY-HINDERED 2-PYRIDINETHIONE LIGANDS - CRYSTAL-STRUCTURES OF [CUCL(2-SC5H2NH-3-SIME3-6-SIET3)2] AND THE DISULFIDE, [-2-SC5H2N-3,6-(SIME2BUT)2]2

The reactions of Cu(II)X2 species (X = Cl-, NO3-) with 3-(triorganosilyl)pyridine-2-thiols and 3,6-(triorganosilyl)pyridine-2-thiols were investigated. When the less sterically hindered 3-(triorganosilyl)pyridine-2-thiol ligands were used, Cu(I) species of the type [Cu(2-SC5H3NH-3-SiR3)3]+ were isolated. In contrast, use of the sterically demanding ligands (SC5H2NH-3-SiMe3-6-SiEt3) and (SC5H2NH-3,6-SiMe2Bu(t)) yielded the Cu(I) species [Cu(2-SC5H2NH-3-SiMe3-6-SiEt3)2Cl] (2) and [Cu(2-SC5H2NH-3,6-SiMe3Bu(t))2Cl] (3). The sulfur ligands are present as monodentate donors in the neutral thione form, protonated at the pyridine nitrogen. The isolation of 3,3',6,6'-tetrakis(dimethyl-tert-butylsilyl)pyridyl disulfide (4) confirms the role of the thiolates as reductants in the synthesis of the Cu(I) complexes. Crystal data: [Cu(2-SC5H2NH-3-SiMe3-6-SiEt3)2Cl] (2), monoclinic P2(1)/c, a = 16.845(3), b = 13.421(2), c = 17.288(3) angstrom, beta = 92.46(1)-degrees, V = 3904.8 angstrom 3, Z = 4, D(calc) = 1.18 g cm-3. Structure refinement and solution based on 1810 reflections converged at 0.065. C34H64N2Si4S2 (4), orthorhombic Pbcn, a = 12.720(2), b = 15.521(3), c = 21.162(3) angstrom, V = 4177.8(10) angstrom 3, Z = 4, D(calc) = 1.07 g cm-3, 2290 reflections, R = 0.058.