Theoretical study of metal ligand aromatic cation–π interactions of [Co(NH 3 ) 6 ] 3+ with benzene

In this work, density functional theory calculations on geometries and energies of all possible conformers of the [Co(NH 3 ) 6 ] 3+ –C 6 H 6 cation–π complex are described. The calculations show that stationary points are several η 2 and the η 3 structures. The most stable η 3 structure has bonding energy, after basis set superposition error correction, of 32.18 kcal/mol. The energies of η 3 structures are similar; also, the energies of η 2 structures are similar while the difference in energy between η 3 and the η 2 structures is about 2 kcal/mol. This indicates a possibility for various orientations of the benzene ring with respect to interacting ligands in the case of metal ligand aromatic cation–π (MLACπ) interactions and a possibility for the existence of these interactions in different molecular systems. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002