Solvent effects on the spin-spin coupling constants of acetylene revisited: supermolecular and polarizable continuum model calculations.

Abstract

The solvent shifts of the spin-spin coupling constants of acetylene were calculated using the polarizable continuum model (PCM) for solvents ranging in polarity from cyclohexane to water, using both density functional theory (DFT) and the complete active space self-consistent field (CASSCF) method. The spin-spin coupling constants were also calculated for complexes of acetylene with water, acetonitrile, acetone and benzene using DFT/B3LYP. It is demonstrated that PCM reproduces the substantial experimental solvent shifts of the (1)J(C,C) and (1)J(C,H) couplings with great accuracy. The sign and approximate magnitude are also rendered correctly by the supermolecular method, in spite of the limitation of the models, which included only one or two solvent molecules.