THE PROMOTION OF AIR OXIDATION AND CARBONYL SUBSTITUTION-REACTIONS OF[(ETA(5)-C5H5)(2)MO-2(CO)(4)(MU-RCCR')] BY TRIMETHYLAMINE N-OXIDE OR NITROSONIUM TETRAFLUOROBORATE - THE SYNTHESIS OF [(ETA(5)-C5H5)(2)MO-2(O)(2)(MU-O)(MU-RCCR')] (R=R'=CO2ME OR PH, R=H, R'=PH, OR R=H, R'=CO2ME) AND [(ETA(5)-C5H5)(2)MO-2(CO)(3)(NO)(MU-RCCR')][BF4] (R=R'=CO2ME, ME OR H, OR R=H, R'=CO2ME)

Trimethylamine N-oxide promotes the air oxidation of [(eta(5)-C5H5)(2) Mo-2(CO)(4)(mu-RCCR')] to afford the novel organometallic oxo complexe s [(eta(5)-C5H5)(2)Mo-2(O)(2)(mu-O)(mu-RCCR')][R = R' = CO2Me or Ph; R = H, R' = Ph; or R = H, R' = CO2Me). Trimethylamine N-oxide also prom otes the near quantitative substitution of one of the carbonyl groups in [(eta(5)-C5H5)(2)Mo-2(CO)(4)(mu-MeO2CC2CO2Me)] by either (BuNC)-N-t or (MeO)(3)P (L), giving [(eta(5)-C5H5)(2)Mo-2(CO)(3)(L)(mu-MeO2CC2CO 2Me)] at room temperature. The addition of [NO][BF4], in place of Me3N O, to solutions of [(eta(5)-C5H5)(2)Mo-2(CO)(4)(mu-RCCR')] under the s ame reaction conditions, does not promote air oxidation but leads inst ead to the new dimolybdenum nitrosyl complexes [(eta(5)-C5H5)(2)Mo-2(C O)(3)(NO)(mu-RCCR')I[BF4] (R = R' = CO2Me, Me or H; or R = H, R' = CO2 Me). The structure of (5)-C5H5)(2)Mo-2(CO)(3)(NO)(mu-MeO2CC2CO2Me)][BF 4] has been determined by X-ray crystallography.