Cyclotriphosphazanes and bicyclic tetraphosphapentazanes

An unusual ring contraction-rearrangement occurs in the reactions of triflu oroethoxy/aryloxy lambda(3)-cyclotriphosphazanes and the bicyclic phosphaza ne, (EtN)(5)P-4(OPh)(2) (L) with tetrachloro-1,2-benzoquinone (TCB) to give lambda(5)-cyclodiphosphazanes. The bicyclic phosphazane monoxide, (EtN)(5) P-4(O)(OPh)(2) (L') undergoes oxidative addition with TCB with retention of the P4N5 ring. Treatment of bicyclic phosphazane L and its monoxide L' wit h [Mo(CO)(4)(NBD)] (NBD = norbornadiene) gives the chelate complexes [Mo(CO )(4)(P-P)] (P-P = L or L'). The structures of the products have been elucid ated by high field P-31, NMR and X-ray crystallographic studies.