Theoretical ab initio calculation of the indirect nuclear spin-spin coupling constants of monohetero cyclopropanes and cyclopropenes via the equations-of-motion method

Nonempirical calculations using the equations-of-motion approach, which includes the main portion of electron correlation effects, are reported for the one-bond coupling constants in the three-membered rings borirane, cyclopropane, azirane, oxirane, silirane, phosphirane, and thiirane and related double-bond analogs. The important overall result is that the 1 J (CC) and 1 J (CC) constants are spread over broad ranges, much wider in the case of the double-bond species, with a nearly regular increase with the electronegativity of the central heteroatom. For the boron cycles the smallest 1 J (CC)'s are predicted, with 1 J (CC) surprisingly lower than 1 J (CC). This exceptional pattern is accounted for in terms of the peculiar electronic structure of these rings formed by the electron-deficient B atom. The 1 J (Heteroatom-C), 1 J (Heteroatom-H) and 1 J (CH) couplings correlate correctly with the available experimental data.