Weak distance dependence of through-bond interactions in tetrahydro-4H-thiopyran-4-ylidene end-capped oligo(cyclohexylidenes); a computational survey

Abstract

Calculations on members of the oligo(cyclohexylidene) series [1(n), n = 1–5)] and related tetrahydro-4H-thiopyran end-capped analogues [2(n), n = 1–4)] show a strong through-bond coupling between their π bonds and sulfur lone pairs (Lp_πS). This coupling is mediated by an interaction between the H(ax)–C–C–H(ax) structural sub-units and the π bonds connecting the cyclohexyl moieties. A comparison of the length dependency of the through-bond coupling via an oligo(cyclohexylidene) and an alkane bridge [divinyl alkanes 3(n)] shows that oligo(cyclohexylidenes) are more efficient in mediating through-bond couplings over large distances. Oligo(cyclohexylidene) bridges exhibit molecular wire characteristics.