Stereochemical Aspects of the Dimerisation of Phosphazo-compounds

The review considers the influence of the electronic and steric structures of phosphazo-compounds on the position of their monomer–dimer equilibrium in solution. It is shown that, for acyclic phosphazo-compounds, the decisive factors are, together with steric factors, the apicophilicity of the substituents at the phosphorus atom and the donor–acceptor properties of the substituents at the nitrogen atom of the phosphazo-group. The shift of the equilibrium towards the dimers observed for phosphazo-compounds with strained five-membered phosphorus-containing heterocycles can be accounted for by the increased apicophilicity of the endocyclic substituents at the phosphorus atom. Other characteristic features of the dimerisation of cyclic phosphazo-compounds are also discussed.
The bibliography includes 62 references.