Length-dependence of intramolecular electron transfer in σ-bonded rigid molecular rods: an ab initio molecular orbital study

Abstract

The dependence of electron transfer (ET) coupling element, V AB, on the length of rigid-rod-like systems consisting of bicyclo[1.1.1]pentane (BCP), cubane (CUB), and bicyclo[2.2.2]octane (BCO) monomers, has been investigated with the use of ab initio Hartree–Fock (HF) method employing Marcus–Hush two-state (TS) model. The value of V AB decreases exponentially with increase in the number of the cage units of the σ-bonded molecules. The calculated decay constant, β, shows good agreement with previously reported data. For molecular length⩾15 A ̊ , the value of V AB becomes negligibly small, suggesting complete suppression of the through bond direct tunneling contribution to ET process.