Oxy-functionalization of Group 9 and 10 transition metal methyl ligands: use of pyridine-based hemi-labile ligands
Hemi-labile ligands (HLLs) are intriguing candidates for catalysts since they may facilitate bond activation and bond formation through facile ligand dissociation/association. DFT studies are reported of hemi-labile ligands in conjunction with Group 9 and 10 metals for oxygen atom insertion into metal–methyl bonds. Analysis of the reaction of pyridine-N-oxide with d8-[LnM (Me)(THF)]q+ (M = Co, Rh, Ir, Ni, Pd, Pt; Ln = 2-(CH3OCH2)Py; q = 0 and +1 for Group 9 and 10 metals, respectively; Py = pyridine; THF = tetrahydrofuran) indicates that oxy-insertion for Group 9 complexes occurs with lower free energy barriers than their Group 10 congeners. Analysis of structural changes along the reaction coordinate suggests that the initial oxygen atom transfer and subsequent methyl migration steps are favored by a reduction and increase, respectively, in coordination number. This emphasizes that HLLs could be uniquely positioned to assist both transformations within a single complex. Additionally, such ligands are worthy of experimental study due to their ability to meet the disparate coordination demands for two-step, redox-based oxy-insertion.