Isotope effects on the stability of the hydrogen-bonded C2H2 NCH, H2O XH3 (X = N, P, As) and F2CH2 NH3 complexes

Abstract

A computational study of three sets of binary hydrogen-bonded complexes was undertaken at the M062x/6–311++G(2d,2p) level of theory to investigate the relative stabilities of mono-deuterated isotopomers of these complexes. This work allows for a comparison of the relative magnitudes of hydrogen and deuterium bonds at low temperatures in (i) the linear and T-shaped optimized structures of C2H2 NCH, (ii) in the H2O XH3 (X = N, P, As) series, where the strength of red-shifted hydrogen bonding is systematically varied via the XH3 basicity and (iii) in the blue-shifted H-bonded F2CH2 NH3 interaction. The deuterium-bonded isotopomers predominate and this energetic preference is rationalized by reference to a simple theoretical model.