M(SR)3L2] complexes of ruthenium(IV,III) and osmium(IV): structural integrity of the trigonal [M(SR)3]+,0 cores

Abstract

In contrast to the considerable chemistry of iron thiolate complexes, the chemistry of ruthenium and osmium thiolate compounds has been less extensively developed. We have previously reported the synthesis of ruthenium and osmium compounds with sterically hindered aromatic thiolate ligands. Herein we report that the systematic elaboration of the coordination chemistry of Ru and Os thiolate complexes reveals the integrity of the trigonal [M(SR)[sub 3]][sup +,0] cores. The compounds [M(SR)[sub 4](CH[sub 3]CN)] (M = Ru, Os; RS = S-2,3,5,6-Me[sub 4]C[sub 6]H, S-2,4,6-i-Pr[sub 3]C[sub 6]H[sub 2]) have trigonal bipyramidal structures with the CH[sub 3]CN and a thiolate ligand occupying the axial positions. The observation that the Ru-S[sub ax] bond distance is almost 0.2 [angstrom] longer than the Ru-S[sub eq] bonds suggested that the axial thiolate could be selectively replaced. The reaction of [M(SR)[sub 4](CH[sub 3]CN)] (M = Ru, Os; RS = S-2,3,5,6-Me[sub 4]C[sub 6]H, S-2,4,6-i-Pr[sub 3]C[sub 6]H[sub 2]) with HBF[sub 4] (or HPF[sub 6]) in CH[sub 3]CN gives [M(SR)[sub 3](CH[sub 3]CN)[sub 2]][BF[sub 4]]. The X-ray crystal structure of a representative member of this series, [Ru(S-2,3,5,6-Me[sub 4]C[sub 6]H)[sub 3]-(CH[sub 3]CN)[sub 2]][PF[sub 6]] (1), was determined. The structure is similar to that of [Ru(S-2,3,5,6-Me[sub 4]C[sub 6]H)[sub 4](CH[sub 3]CN)] (2) but with a CH[submore » 3]CN molecule replacing the axial thiolate ligand; two of the equatorial thiolate ligands are oriented in the direction of one of the axial CH[sub 3]CN ligands, and the third thiolate is directed toward the second CH[sub 3]CN ligand (i.e., the 2-up, 1-down conformation). The Ru-S[sub eq] distances (2.200 (8) [angstrom]) in 1 are unchanged compared to 2, but the Ru-N distances in 1 are 0.06 [angstrom] shorter than the Ru-N distance in 2.« less