Is Ti(η8-pentalene)2 a 20-electron complex? A theoretical investigation of a pseudo electron-rich molecule

Abstract

DFT calculations confirm the D_2d conformation of the title compound proposed by Jonas et al; only 9 of the 10 combinations of the π-type ligand orbitals interact with the metal atom: the remaining one, of a₂ symmetry, does not match with any metal orbital and therefore the title compound is not a 20-electron system, but a regular 18-electron complex; calculations predict that the 18-electron [Ti(η⁸-pentalene)₂]²⁺ cation should also be attainable.