¹³C–⁷⁷Se and⁷⁷Se–⁷⁷Se spin–spin coupling tensors in carbon diselenide: NMR experiments and ZORA DFT calculations

The isotropic average and anisotropy of the 13C–77Se and 77Se–77Se spin–spin coupling tensors in carbon diselenide (CSe2) were calculated by applying relativistic density functional theory. Computed nuclear shielding anisotropies are also reported. The coupling tensor anisotropies were derived experimentally with the liquid crystal (LC) NMR method. Due to the fact that the number of adjustable parameters in the experimental analysis is greater than the number of anisotropic coupling constants, DexpMN, the ratio of the coupling tensor anisotropies, ΔJCSe/ΔJSeSe, had to be fixed to the value obtained from the calculations. It appears that both tensor anisotropies are large, and in particular ½JanisoSeSe is a clearly dominating contribution in DexpSeSe. The remarkable ½JanisoCSe contribution in the DexpCSe leads to a correction of the earlier reported shielding tensor anisotropies, ΔσC and ΔσSe, determined by LCNMR.