STUDY OF THE SYNERGY IN ELECTRON-RICH ELEMENT CARBORANE COMPOUNDS - ANTIPODAL BORON ATOM LABILIZATION BY ELECTRON-RICH ELEMENTS - CONVERSION OF (7-SR-8-ME-7,8-C2B9H10)- INTO (7-SR-8-ME-7,8-(5)-C2B8H11)-

The reaction of nido-[NMe4]{7-SMe-8-Me-7,8-C2B9H10} with [RuCl2(PPh3)3 ] leads to the formation of [RuCl{7-SMe-8-Me-7,8-(5)-C2B8H11}(PPh3)2]. The new C2B8 carborane ligand has a peculiar arachno structure that r esults from eliminating B(5) in the former C2B9H12- nido precursor. Th e geometry is basketlike with a B-B handle. The reaction takes place f or other {7-SR-8-Me-7,8-C2B9H10}- ligands, R = Me, Et, iPr, nBu, and b enzyl. The complex was characterized (R = Me) by an X-ray diffraction study. Dark red crystals were monoclinic, space group Pn (No. 7), with Z = 2, a = 10.751(2) angstrom, b = 14.369(3) angstrom, c = 16.073(3) angstrom, beta = 95.83(1)-degrees, V = 2470(1) angstrom3, and R(w)(F(o )) = 0.063 for 3957 reflections having I greater-than-or-equal-to 2.5s igma(I).