Ab initio study of the protic conversion of an allene into an η2-vinyl complex of Re, and on their structure, bonding and redox behaviour†
Abstract
Ab initio quantum-chemical methods at the RHF/UHF and MP2 levels of theory were applied to the investigation of the structure, bonding, reactivity and electrochemical behaviour of a rhenium(I)-bis(diphosphine) η2-allene complex and of the corresponding η2-vinyl product derived from protonation, by using the models trans-[ReCl(η2-H2CC
CH2)(PH3)4] and trans-[ReCl{η2-C(CH2)CH3}(PH3)4]+. Full geometry optimization of the models was carried out and the electrostatic potential distributions and MO compositions were calculated, allowing not only the interpretation of the co-ordination bonds of the η2-allene and the η2-vinyl
C
CH2)(PH3)4]+ and trans-[Re(ClH){η2-C(CH2)CH3}(PH3)4]2+, which were not identified in a previous stopped-flow spectrophotometric study, thus supporting an unprecedented role, in the protonation reaction, of the