Oxidative addition and reductive elimination are perhaps the most characteristic reactions of late transition metal complexes, and are critical steps in most catalyses which they effect. While it is often assumed that increased electron-donating ability of ancillary ligands favors oxidative addition, the fact that oxidation state is a formalism should call such an assumption into question. Oxidative addition to three-coordinate d8 fragments is particularly important in late-metal catalysis. We have conducted a combined theoretical and experimental study which demonstrates that the thermodynamics of addition of R-R' (R, R' = H, hydrocarbyl, amino) to L2XIr to give trans-L2IrXRR' (and related reactions) are, in disagreement with the generally accepted rules, relatively unaffected by the electron-donating ability of L and strongly disfavored  by increased electron-donating ability of X. It is found that the iconic oxidative addition to square-planar d8 complexes also does not generally show any simple dependence on ancillary ligand electron-donating ability.

Factors affecting the "oxidative" addition of N-H and C-H bonds to iridium complexes

243rd National Meeting (2012)

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