Correlation effects in the long-range coupling between acetylenic π-electrons in a series of α,ω-diethynyl[n]staffanes (n = 1–5) Original Research Article

The electronic factor Δ for electron transfer between two acetylene molecules connected by a saturated oligostaffane spacer is calculated using ab initio methods with electron correlation included at the MP2 level. It is found that the inclusion of relaxation and correlation effects increases the value of the decrease factor, β, i.e. the interaction between the acetylenic π-orbitals decreases faster with the distance than predicted at the Hartree-Fock level. Our calculations suggest that the electron transfer capability of the staffane bridges is possibly lower than previous results obtained at simpler levels of the theory seemed to indicate.