1H-Phosphiranes and -enes invert at phosphorus via a turnstile rotation

Abstract

Ab initio (CCSD(T)/6-31+G*) calculations suggest that 1H-phosphiranes and 1H-phosphirenes invert their configuration at phosphorus by a rotation of the PX group (X = H, F, Cl, Br) above the C ₂ moiety, rather than the more usual planar trigonal inversion pathway via a C _2v transition state.