Effect of Fluorine and Chlorine Substituents on Stabilities of Diphosphaallene, Diphosphirene, and Phosphanylphosphaalkyne Isomers (XX′ CP2 Species with X, X′ = H, F, and Cl)

Abstract

AbstractAb initio MO calculations at the QCISD(T)/6–31G* */MP2/6–31G* * + ZPE level on the XX′CP2 isomers (X = H1 F and Cl) show that the energies of the isomeric species are often reordered following halogen substitution. The phosphorushalogen moiety behaves as the main stabilizing factor on the rest of the molecular structure. This is particularly true when X = F is involved. In the dihalogenated series phosphanyl‐phosphaalkyne (4) becomes the most stable species followed by diphosphaallene (3) and 1 H‐diphosphirene (6). The effect on the geometry following halogenation is larger if substitution takes place at carbon than at phosphorus. The behaviour of the P species is found to be quite different from, if not opposite to, that of their nitrogen analogues. Finally, the infrared spectra of the most stable isomers are also predicted.