Single-electron oxidation of monomeric copper(I) alkyl complexes: Evidence for reductive elimination through bimolecular formation of Alkanes

Monomeric Cu(I) alkyl complexes (NHC) Cu(R) (NHC = N-heterocyclic carbene; R = or Et) and (dtbpe) CuMe) (dtbpe) 1,2-bis(di-tert-butylphosphino) ethane) have been prepared, isolated, and characterized. Single-electron oxidation of the Cu(I) alkyl complexes upon reaction with AgOTf to form putative Cu(II) intermediates of the type [(L)Cu(R)](+)(L = NHC or dtbpe, R = Me or Et) results in the rapid production of (L) Cu(X) (X = OTf) and R-2. Experimental studies suggest that the reductive elimination of R2 from Cu( II) occurs through a nonradical bimolecular mechanism. Computational studies of the Cu-C-methyl yield bond dissociation enthalpies of [(SIPr)Cu-CH3](n+) (80 kcal/mol for n=0 {Cu(I)} and 38 kcal/mol for n = 1 {Cu(II)}).