Coordination chemistry of silanedithiolato ligands derived from cyclotrisilathiane: Synthesis and structures of complexes of iron(II), cobalt(II), palladium(II), copper(I), and silver(I)

The coordination chemistry of chelating silanedithiolato ligands has been investigated on Fe(II), Co(II), Pd(II), Cu(I), and Ag(I). Treatment of M(OAc)₂ (M = Fe, Co, Pd) with cyclotrisilathiane (SSiMe ₂)₃ in the presence of Lewis bases resulted in formation of Fe(S₂SiMe₂)(PMDETA) (1), Fe(S₂SiMe ₂)(Me₃TACN) (2), Co(S₂SiMe₂)(PMDETA) (3), and Pd(S₂SiMe₂)(PEt₃)₂ (4) (PMBETA = N,N,N′,N′,N″-pentamethyldiethylenetriamine; Me ₃TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane). The analogous reactions of M(OAc) (M = Cu, Ag) in the presence of PEt₃ gave rise to the dinuclear complexes M₂{(SSiMe₂) ₂S}(PEt₃)₃ [M = Cu (5), Ag (6)]. Complexes were characterized in solution by ¹H, ³¹P{¹H}, and ²⁹Si{¹H} NMR and in the solid state by single-crystal X-ray diffraction. Mononuclear complexes 1-3 have a four-membered MS ₂Si ring, and these five-coordinate complexes adopt trigonal-bipyramidal (for the PMDETA adducts) or square-pyramidal (for the Me₃TACN adduct) geometries. In dimer 6, the (SSiMe₂) ₂S^2- silanedithiolato ligand bridges two metal centers, one of which is three-coordinate and the other four-coordinate. The chelating effect of silanedithiolato ligands leads to an increase in the stability of silylated thiolato complexes.