SYNTHESIS, X-RAY STRUCTURE, AND DYNAMIC NMR INVESTIGATION OF SECONDARY CYMANTRENYLCARBENIUM AND FERROCENYLCARBENIUM IONS STABILIZED BY HETEROBIMETALLIC COBALT-MOLYBDENUM CLUSTERS - [(MOCO(CO)(5)CP)(MU-MN(CO)(3)CPCHC-CCH3)]- AND [(MOCO(CO)(5)CP)(MU-FCCHC-CCH3)]+BF4-(BF4)

A solution-phase variable-temperature H-1 NMR investigation was perfor med on (MoCo(CO)(5)Cp)(mu-Mn(Co)(3)CpCHC=CCH3)](BF4-)-B-+ (4), [(MOCO( CO)(5)Cp)(mu FcCHC=CCH3)](+)BF4(-) (5b), and [(MoCo(CO)(5)Cp)(mu-FcCHC =C(CH2)(4)CH3)](+)BF4(-) (5c), The NMR spectra were temperature depend ent for 4 and for 5b,c. The fluxional process could be ascribed to sim ple rotation around the C+-cluster bond, In addition the X-ray structu re of the complexes a and 5b were determined. In all cases it appears that the molybdenum plays a major role in the stabilization of the pos itive charge.