Probing the structural and magnetic properties of transition metal-benzene anion complexes

Abstract

Two types of transition metal–benzene anion complexes, (titanium)_n(benzene)⁻_m and (cobalt)_n(benzene)⁻_m (n ≤ 2, m ≤ 3) have been determined using density functional theory. The photoelectron spectra of Ti_nBz⁻_m and Co_nBz⁻_m (n ≤ 2, m ≤ 3) were discussed from the perspective of quantum chemical calculations of the vertical detachment energies (VDEs) of several low-energy isomers obtained by the structural optimization procedure. The binding of Ti and Co atoms to benzene molecules is accounted by 3d-π bonds, as revealed by the molecular orbitals. The topology of the electronic density has been analyzed, suggesting that the C–C bonds were weakened in the transition metal–benzene complexes in comparison to those in free benzene. Spin density distribution results show the spin densities for Ti_nBz⁻_m and Co_nBz⁻_m (n ≤ 2, m ≤ 3) reside mainly on the metal Ti and Co centers (70%–90%). A shift to lower magnetic moment with respect to the pure titanium/cobalt cluster anions indicates the solvent benzene molecule acts to demagnetize the bare titanium/cobalt cluster anions.