Hafnium-rhodium and hafnium-iridium heterobimetallic complexes featuring the bridging germole dianion ligand [GeC4Me4](2-)

The complex [Cp*(eta(5)-C4Me4Ge)HfMe2Li(THF)](2) (1; Cp* = C5Me5), prepared via treatment of Cp*HfMe2Cl with 2 equiv of Li[C4Me4GeSiMe3], reacted rapi dly with 2 equiv of (PMe3)(4)RhOTf (OTf = OSO2CF3) to give the novel Rh(III ) zwitterionic complex ansa-{eta(4)-C4Me4Ge[Rh(PMe3)(4)H](eta(5)-C4Me4CH2)} HfMe2 (2), via loss of LiOTf. An intermediate in this reaction, presumed to be Cp*{eta(5)-C4Me4Ge[Rh(PMe3)(4)])HfMe2 (8), was observed at low temperat ure by P-31 NMR spectroscopy. Reactions of 1 with (dmpe)(2)MOTf(dmpe = 1,2- bis(dimethylphosphino)ethane; M = Rh, Ir) produced the complexes Cp*{eta(5) -CrS-C4Me4Ge[Rh(dmpe)(2)]}HfMe2 (5) and Cp*{eta(5)-C4Me4Ge[Ir(dmpe)(2)]}HfM e2 (6), respectively. Complexes 5 and 6 possess the [GeC4Me4](2-) ligand, w hich bridges the two metal atoms in a sigma,pi fashion.