Structure and reactivity of (eta-C(5)R(5))Mo(NO)(2)-halide, -halomethyl, and -alkyl complexes: Consecutive aerobic methylene and nitrosyl ligand oxidation

Cp'Mo(NO)(2)(CH(2)X) complexes are isolated in 80-90% yield after the treatment of the Cp'Mo(NO)(2)X complexes in CH2Cl2 with ethereal diazomethane in the presence of Cu powder (Cp' = eta-C5H5 (CP), eta-C-5(CH3)(5)(Cp*); X = Cl, Br). The Cp'Mo(NO)(2)(CH2I) derivatives are obtained in over 90% yield by treating the Cp'Mo(NO)(2)(CH2Cl) derivatives with NaI in THF. Four new halomethyl complexes have been characterized by X-ray crystallography and are compared to the related CpMo(NO)(2)Br, Cp*Mo(NO)(2)Cl, and Cp*Mo(NO)(2)(CH3) derivatives. The structural data and IR data indicate the donor properties of the halomethyl ligands to be intermediate between halide and alkyl ligands. The Cp'Mo(NO)(2)(CH(2)X) complexes react initially with O-2 to give CH2O and the regeneration of the parent Cp'Mo(NO)(2)X complexes. The Cp'Mo(NO)(2)Cl complexes react with O-2 after an induction period to give the well-known Cp'MoO2Cl complexes, NO2, NOCl, and N2O. Exposure of CpCr(NO)(2)(CH(CH3)Br) to O-18(2) gives O-18=CH(CH3) and O-16-labeled CpCr(NO)(2)Br. The Cp'Mo(NO)(2)-alkyl complexes react with O-2 to give the corresponding Cp'MoO2-alkyl derivatives in 40-70% yield (alkyl = CH3, CH2CH3). Electrochemical data show the Mo complexes to oxidize at 0.2-0.3 V lower than the Cr congeners.