Are the anions MeO(CO)n- (n=1 and 2) methoxide anion donors in the gas phase? A theoretical investigation

1. The anions CH3O--CO and CH3OCO--CO are both methoxide anion donors. The processes CH3O--CO -> CH3O- + CO and CH3OCO-CO -> CH3O- + 2CO have Delta G values of +8 and -68 kJ mol(-1), respectively, at the CCSD(T)/6-311++G(2d, 2p)//B3LYP/6-311++G(2d,2p) level of theory. 2. The reactions CH3OCOCO2- -> CH3OCO2- + CO (Delta G = -22 kJ mol(-1)) and CH3COCH(O-)CO2CH3 -> CH3COCH(O-)OCH3 + CO (Delta G = +19 kJ mol(-1)) proceed directly from the precursor anions via the transition states (CH3OCO center dot center dot center dot CO2)(-) and (CH3COCHO center dot center dot center dot CH3OCO)(-), respectively. 3. Anion CH3COCH(O-)CO2CH3 undergoes methoxide anion transfer and loss of two molecules of CO in the reaction sequence CH3COCH(O-)CO2CH3 -> CH3CH(O-)COCO2CH3 -> [CH3CHO (CH3OCO--CO)] -> CH3CH(O-)OCH3 + 2CO (Delta G = +9 kJ mol(-1)). The hydride ion transfer in the first step is a key feature of the reaction sequence. Copyright (C) 2010 John Wiley & Sons, Ltd.