Electronic structure, nature of bond and carbonyl vibrational frequency analysis of half-sandwich complexes [(η6-arene)M(CO)3] (arene = hexafluorobenzene, 1,3,5-trifluorobenzene, benzene, 1,3,5-trimethylbenzene, hexamethylbenzene; M = Cr, Mo, W); A theoretical study

Abstract

In this paper, half-sandwich complexes [(η6-arene)M(CO)3] (arene = hexafluorobenzene, 1,3,5-trifluorobenzene, benzene, 1,3,5-trimethylbenzene, hexamethylbenzene; M = Cr, Mo, W) have been studied theoretically. The conformational space of tripodal rotation of M(CO)3 moiety of all complexes has been studied, at BP86D3/def2-TZVP and M06L/def2-TZVP levels of theory. The different types of interaction energies between the fragments were calculated and it was shown that the presence of electron-donating or electron-withdrawing groups on the arene ring affects both the M–arene and metal–carbonyl bonds. The symmetric and anti-symmetric CO stretching modes were studied and a good correlation between the calculated and available experimentally measured values was observed. The effect of substitutions at arene on the CO stretching frequencies was further confirmed by a good correlation between the total interaction energies and the calculated carbonyl stretching frequencies. The nature of M(CO)3–arene bonds was studied and the results showed that the contribution of orbital interactions is more than electrostatic.