Theoretical Study on the Dissociation of Ligands in the Rhodium and Iridium Complexes Containing 1,1,1,5,5,5-Hexafluoroacetylacetonato

Functionalization of the inert C? H bonds of unsaturated molecules by transition metal complex is an important means to form new C? C bonds. The functionalization is usually initiated by the ligand dissociation of a complex. In this paper we employ both ab initio and density functional methods to explore the influence of central metals, conformation, solvent and protonation on the ligand dissociation of the (hfac‐O,O)₂M(L)(py) complexes M=Rh(III) or Ir(III), hfac‐O,O=k²‐O,O‐1,1,1,5,5,5‐hexafluoroacetylacetonato, L=CH₃, CH₃CO₂, (CH₃CO)₂CH, CH₃O or OH, py=pyridine]. We demonstrate that ligand pyridine dissociates more easily than the "L" ligands under study in aprotic solvent and gas phase and the dissociation of pyridine is more facile in the trans‐conformation than in the cis‐isomer. These phenomena are rationalized based on electronic structure and molecular orbital interactions. We show that solvation only slightly stabilizes the complexes and does not change the ligand dissociation ordering. In particular, we show that pyridine is no longer the labile ligand in protic media. Instead, the oxygen‐containing ligands (apart from those like hfac that form a cyclic structure with the central metal) that coordinate to the central metal via oxygen atom become the labile ones. Finally our calculations indicate that hfac is a stable ligand, even in protic media.