Comparative Reactivity of Zr– and Pd–Alkyl Complexes with Carbon Dioxide

摘要: Structure/reactivity trends and DFT studies reveal mechanistic differences parallels for the carboxylation of Zr Pd alkyls. CO2 reacts with Cp2ZrMe(C6D5Cl)+ >104 faster than Cp2ZrMe2, yielding monoacetate products in both cases. These reactions proceed by insertion mechanisms which Zr- - -O interactions activate CO2. In contrast, readily [(PO-iPr)PdMe2]− (PO-iPr– = 2-PiPr2-4-Me-C6H3SO3–) to yield [(PO-iPr)PdMe(OAc)]− but not (PO-iPr)PdMe(L) species. Carboxylation occurs direct SE2 attack at Pd–Metrans-to-P group, nucleophilicity Pd–Me group controls reactivity. However, process is accelerated a Li+- - -OCO interaction when Li+ present.