Synthesis of azadiphosphiridine complexes. Theoretical studies on ring formation, the P-to-P' metal shift and the resulting nitrogen geometry.

A set of azadiphosphiridine complexes 3a and 4b,c were synthesized in high selectivity using N-H and P-H deprotonation as key steps and RPCl 2 as substrates (R = N i Pr 2 ( a ), - t Bu ( b ), Ph ( c )). While complex 3a ( P -N i Pr 2 ) retained the P-W linkage of the starting material W(CO) 5 {Ph 3 CP(H)NH}, complexes 4b ( P - t Bu) and 4c ( P -Ph) revealed that a P-to-P' haptotropic shift of the W(CO) 5 group has occurred. Remarkably, complex 3a, bearing an unligated P -N i Pr 2 unit, displays a planar ring N geometry while 4b,c showed a pyramidal geometry of the ring nitrogen atom. Theoretical studies on the ring formation including the P-to-P' haptotropic metal shift and the factors influencing the ring nitrogen geometry are reported.