VERSATILITY OF NIDO-MONOPHOSPHINOCARBORANES AS LIGANDS - TRICOORDINATION VIA PPH2 AND BH IN RHODIUM(I) COMPLEXES

Reaction of [NMe4][7-PPh2-8-R-7,8-C2B9H10] (R = H, Me) with [Rh-2(mu-C l)(2)(cod)(2)] in dichloromethane yielded [Rh(7-PPh2-8-R-7,8-C2B9H10)( cod)] (R = H, Me). The carborane Ligand coordinates the Rh through Cc- PPh2, B(11)-H, and B(2)-H. The Rh(I) atom is pentacoordinated, assumin g that cod is bidentate. The B-H-Rh resonances in the H-1 NMR spectra appear in the interval between +2 and +3 ppm, as a consequence oft he trans influence generated by cod. The structure was fully elucidated b y a crystal diffraction analysis of [Rh(7-PPh2-8-Me-7, 8-C2B9H10)(cod) ]. The B-H-->Rh agostic bonds exist both in the solid state and in sol ution, as was proven by B-11 NMR.