The reaction of metal alkyls with CO2 to yield metal carboxylates plays a prominent role in strategies for the conversion of CO2 to value-added chemicals. These reactions can proceed by insertion mechanisms involving M- - -OCO interactions or by direct SE2 attack of CO2 at the metal alkyl carbon. In this presentation, the reactions of CO2 with prototypical Zr and Pd LxMRn+ oleﬁn polymerization catalysts and the corresponding LxMR2(n-1)+ species will be discussed. These studies provide insight into the mechanistic diﬀerences and parallels in the carboxylation of early- and late-transition-metal alkyls. The carboxylation of Zr alkyls proceeds by insertion mechanisms in which M- - -OCO interactions activate the CO2, whereas the carboxylation of Pd alkyls proceeds by SE2 at the Pd-Me, and the nucleophilicity of the Pd-Me group controls the reactivity. However, the SE2 process is accelerated by M- - -OCO interactions when Li+ is present. The reactions of CO2 with pairs of metal alkyl complexes that differ only in oxidation state and charge, LxMRn vs. LxMRn+, will also be discussed.

Comparative reactivity of CO2 with transition metal alkyls

249th National Meeting (2015)

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