Insight into the mechanism of R-R reductive elimination from the six-coordinate d⁶ complexes L₂Pt(R)₄ (R = vinyl, Me)

We have used density functional theory to investigate the reductive elimination from platinum(IV) structures of the form L₂PtR ₄ where L = PMe₃, PH₃, PF₃, CO, NH₃ and R = vinyl, Me. We conclude that reductive elimination occurs via the L-predissociation pathway for R = Me, irrespective of ligand L. But when R = vinyl, direct elimination is the preferred pathway if the L ligand is PMe₃; otherwise both pathways are competitive for R = vinyl. We also note that if L is more π-electron accepting and less σ-electron donating, the reductive elimination from the six-coordinate complexes L ₂PtR₄ will be more rapid. Reductive elimination from the five-coordinate complexes LPtR₄ proceeds more easily if the ligand trans to the two R groups being coupled is more σ-electron donating and the ligands cis to the two R groups are more π-electron accepting.