Cyclic Phosphorus(V) Compounds: Phosphazanes and Anhydrides

31P n.m.r. has been extensively used to study the preparation and reactions of cyclic phosphorus-(V) compounds containing P-N-P and P-O-P linkages. Michaelis “Oxyphosphazobenzolchlorid”,[C6H5NPOCl]n has been shown by 31P n.m.r. and mass spectroscopy to be the trimer (n=3), not the dimer as proposed by Michaelis. The competing reactions of aniline hydrochloride and POCl3 to form the dimer (two isomers cis- and trans-) and the trimer have been elucidated. With PSCl3 only the dimer [C6H5NPSCl]2 is formed (both isomers).