JAHN-TELLER AND PSEUDO JAHN-TELLER ORIGIN OF STRUCTURAL DISTORTIONS OF COORDINATED MOLECULES

A new approach based on an approximate evaluation of the Jahn-Teller effect (JTE), pseudo JTE, and Renner-Teller effect (RTE) in systems with fractional charges is employed to reveal the origin of structural distortions of coordinated formaldehyde and allene molecules in comparison with their structure as a free system. It is shown that the orbital charge transfers to formaldehyde in the Fe(CO)(2)(PH3)(2)(eta(2)-CH2O) and Fe(PH3)(4)(eta(2)-CH2O) complexes induce the pseudo Jahn-Teller interaction in CH2O molecule leading to the out-of-plane bending of the latter. The changes in allene geometry by coordination are shown to be due the common action of the JT and PJT effects induced by the orbital charge transfers.