CARBONYLMETAL COMPLEXES (M=CR, MO, W) DERIVED FROM N-BIS(DIISOPROPYLAMINO)PHOSPHINYL-N'-TERT-BUTYL SULFUR DIIMIDE - NOVEL 5-MEMBERED PNSNM METALLACYCLES

N-Bis(diisopropylamino)phosphinyl-N'-tert-butyl sulfur diimide (1) rea cts with THF-stabilized complex fragments [M(CO)(5)] in THF solution t o give the pentacarbonylmetal adducts 2a (M=Cr), 2b (M=Mo) and 2c (M=W ) in which the metal is linked to phosphorus. These complexes are flux ional at room temperature with respect to fast E/Z reversible arrow Z/ E isomerization and adopt the Z/E configuration both at low temperatur e in solution end in the solid state (X-ray analysis of 2c) with the [ M(CO)(5)] fragment in Z position. Complexes 2 lose one CO ligand in da ylight, faster upon UV irradiation, to give the novel metallacycles 3a -c in which the [M(CO)(4)] fragment is part of the MPNSN ring. The str ucture of 3 follows from consistent NMR data (H-1, C-13, P-31 NMR) and also from a single crystal X-ray analysis of 3b.