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 cyclotrisiiathiane (SSiMe2)(3) in the presence of Lewis bases resulted in formation of Fe(S2SiMe2)(PMDETA) (1), Fe(S2SiMe2)(Me(3)TACN) (2), Co(S2SiMe2)(PMDETA) (3), and Pd(S2SiMe2)(PEt3)(2) (4) (PMDETA = N,N,N',N',N' -pentamethyldiethylenetriamine; Me(3)TACN = 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 M-2{(SSiMe2)(2)S}(PEt3)(3) [M = Cu (5), Ag (6)]. Complexes were characterized in solution by H-1, P-31{H-1}, and Si-29{H-1} NMR and in the solid state by single-crystal X-ray diffraction. Mononuclear complexes 1-3 have a four-membered MS2Si ring, and these five-coordinate complexes adopt trigonal-bipyramidal (for the PMDETA adducts) or square-pyramidal (for the Me(3)TACN adduct) geometries. In dimer 6, the (SSiMe2)(2)S(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.