Theoretical study of carbon isotope effects in the nonclassical carbonyl cation CO/[M(CO)n]+ (M = Cu, Ag, Au; n = 1–4)

Abstract

In order to find an ideal exchange system for carbon isotope separation, carbon isotope effects in the CO/[M(CO)n]+ (M = Cu, Ag, Au; n = 1–4) complex system were analyzed using density functional theory calculations, and the isotopic equilibrium constants were calculated as the ratio of the reduced partition function ratios of the 13C/12C isotopic pairs. It is shown that the isotope equilibrium constant changes with the coordination number of CO to the complex as the temperature changes. In CO/[Au(CO)n]+, the contribution of bending vibration to the isotope effect increases, so that a higher isotope effect is expected than CO/[Ag(CO)n]+.