The acid/base properties of aliphatic C-H bonds are relevant to their activity and selectivity in catalysis. One such issue is the deprotonation of the methyl hydrogen, which has shown to be a major competing side reaction especially for catalysis in alkaline conditions. A DFT study of several different complexes comprised of 3d transition metals, Ti, V, Cr, and Mn bonded to at least one methyl group were analyzed to compute the acid/base properties of methyl C—H bonds. The level of theory used was BMK/6+31G(d) and the SMD method using DMSO as the continuum solvent. Deprotonation of the metal-methyl complex by DMSO resulted in the formation of the conjugate acid of DMSO and the conjugate base (anionic metal-methylidene complex). From this, the pKa of methyl deprotonation reaction was calculated to show the effects of metal, ligand, and spin on the likelihood of deprotonation.<br/>

Computational study of the pKa of transition metal-methyl C-H bonds

2019 Fall National Meeting

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