Electronic structure and coordination chemistry of phenanthridine ligand in first-row transition metal complexes: A DFT study

摘要

The geometric parameters, electronic structures, and haptotropic migration of a series of hypothetical compounds of general formula CpM(C _(13)H_9N) and (CO)_3M(C_(13)H_9N) (M = fist row transition metal, Cp = C_5H_5, and C _(13)H_9N = phenanthridine ligand) are investigated by means of the density functional theory. The phenanthridine ligand can bind to the metal through η~1 to η~6 coordination mode, in agreement with the electron count and the nature of the metal, showing its capability to adapt itself to the electronic demand of the metal as well as to the polycyclic aromatic hydrocarbons. In the investigated species, the most favored closed-shell count is 18-electron except for the Ti and V models which are deficient open-shell 16-electron configuration. This study has shown the difference in coordination ability of this heteropolycyclic ligand: the coordination of the central C_5N ring is less favored than the terminal C_6 rings, in agreement with the π-electron density localization. Most of the investigated complexes are expected to exhibit a rich fluxional behavior. This flexibility favors the possibility for the existence of several isomers as well as their interconversion through haptotropic shifts.