Benchmarking the inversion barriers in σ3λ3-phosphorus compounds: a computational study†
The study of inversion barriers for ninety-four P(III)-containing compounds has been carried out using DFT calculations. Most of these compounds display a typical vertex (“umbrella”) transition state (TS) structure, whereas those having very electronegative substituents or belonging to small size (strained) heterocycles display edge (T-shaped) geometries. Only a small set comprising diazaphosphiridines with N-substituents at phosphorus and phosphirenes show a turnstile TS structure featuring one transiently elongated endocyclic P-bond. A classification according to two geometric parameters is proposed. Higher inversion barrier for compounds having electronegative atoms and/or belonging to smaller rings was found as a general trend. Possible relationships between the energy barrier and both electronic and structural parameters at P were also explored.