Reactions of Ph2PNRC(E)NRPPh2 proceed to give simple P,P chelate complexes
when E = O but give the unexpected five-membered true heterocycle Pt[Ph2PN(
Me)C(NMeH)S] Cl-2 and an unusual six-membered Pd2P2O2 ring when E = S. The
X-ray structures of three examples are reported.