Bonding analysis and electronic structure of transition metal-benzoquinoline complexes: A theoretical study

The geometric and electronic structures of a series of hypothetical compounds of the types CpM(C₁₃H₉N) and (CO)₃M(C₁₃H₉N) (M = first row transition metal and C₁₃H₉N = 7,8-benzoquinoline) have been investigated by means of density functional theory (DFT). The benzoquinoline ligand can bind to the metal through η¹-η⁶ coordination modes, adopting structures of types a, b and c, in agreement with the electron count and the nature of the metal. In the investigated species, the most favored closed-shell count is 18-MVE, except for the Ti and V models which prefer the open-shell 16-MVE configuration. This study has shown the difference in the coordination ability of this heteropolycyclic ligand and coordination of the inner C₆ ring is less favored than the outer C₆ and C₅N rings, in agreement with the π-electron density localization.