PH-Triazaphosphorine

Abstract

Equimolar mixtures of a biguanide and a diphenylphosphonite on heating under reduced pressure split off 2 moles of phenol. As products cyclic phosphazanes 3 were to be expected. Instead they undergo a hydrogen shift from N to P to give 2-hydrogen-2-alkyl-4.6-diamino-1.3.5.2-triazaphosphorines (4). This is taken as evidence that a phosphazene π-bond may well become part of a cyclic delocalised system and thus contribute substantially more to stabilize the PH-tautomer than an isolated one. Carbonyl compounds add readily to the PH-bond, CCl4 substitutes the hydrogen for chlorine, which in turn may be displaced by alkoxy and amino groups. 31P- and 1H-NMR data, especially the PH- and PD-coupling patterns sustain the assigned structures.