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-(SiMe₂Bu^t)₂]₂

The reactions of Cu(II)X₂ species (X=Cl^-, NO₃^-) with 3-(triorganosilyl)pyridine-2-thiois 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 P2₁/c, a=16.845(3), b=13.421(2), c=17.288(3) Å, β=92.46(1)°, V=3904.8 ų, 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) Å, V=4177.8(10) ų, Z=4, D_calc=1.07 g cm^-3, 2290 reflections, R=0.058.