Structural and electronic characterisation of the organometallic distonic ion (C6H6)Fe+(p-C6H4)·

Molecular orbital calculations have been used to characterise the structural and electronic properties of the gas-phase distonic radical cation (benzene)Fe+(p-benzyne)·. Geometries and vibrational frequencies were obtained with density functional theory (B3LYP) and additional relative energies calculated with the BLYP, restricted open-shell second order Moller-Plesset (MP2) and spin-projected unrestricted MP2 methods. Doublet, quartet, and sextet spin states were considered. As well as the highly symmetric C(2v) species, a number of structures with lower symmetry were considered. The radical and charge sites are indeed shown to be separated. Complexation energies of benzene with Fe+(p-benzyne)· were calculated and compared with experimental findings. Calculations on (benzene)Fe(o-benzyne)+· and (benzene)Fe(phenyl)+· were also carried out for comparison of structures, electronic properties, and energetics. (C) 2000 Elsevier Science B.V.