Examining the stabilising role of metal centre on inter-ligand delocalisation

Non -innocent ligands are a class of ligands that gains attention in organometallic chemistry in recent years, and many remarkable coordination complexes with multiple non -innocent ligands have been synthesised. These complexes admit special electronic configurations that could be rationalised by "inter-ligand delocalisation". In this work, we make use of the Principal Interacting Orbital analysis we developed to examine the role of metal centre in these cases. We found that the metal orbitals used in such kind of stabilisation can differ between early and late transition metals, and the geometry of the complex is also influenced by symmetry factors. These analyses not only complement the earlier understanding of "inter-ligand delocalisation", but also give hint to the controversial roles of transition metal p orbitals in coordination chemistry.