PHOSPHONIC ACID ANHYDRIDES [RPO(2)](N) - OLIGOMERIZATION AND STRUCTURE

The phosphonic acid anhydrides of the general formula [RPO(2)](n) have been prepared with R = Me, Et, i-Pr, t-Bu, and Ph from the correspond ing phosphonic acids and their chlorides and esters. Mass spectrometri c data indicate that the trimers are the dominant oligomers for all fi ve systems. According to their NMR spectra, the methyl and t-butyl com pounds have a symmetrical (C-3v) structure with equivalent RP groups, while the ethyl, i-propyl and phenyl homologues have the C-s structure with non-equivalent PR groups in the ratio 1:2.