Substituent effects on the bonding properties in cyclotriphosphanes and related compounds. Polarization of Hückel versus Möbius orbitals

Abstract

In inorganic three-membered ring systems containing ring members (P, N, O, or S) with a lone pair, a cyclic conjugated Hückel system is formed. This favours a perpendicular over a bisected orientation of electron-releasing or electon-attracting substituents, causing bond alterations opposite to those predicted previously by Hoffmann and Günther on the basis of the Walsh model.