Synthesis and Crystal Structures of Novel Group 6B Metal Carbonyl Complexes with N-(4-methyl-2-pyridinyl)-P,P-diphenylphosphinous Amide Ligand

The reaction of N-(4-methyl-2-pyridinyl)-P,P-diphenylphosphinous amide ligand 4-Me-C₅H₃N-2-NH(PPh₂) (1) with M(CO)₆ (M=Cr, Mo, W) in refluxing toluene afforded a mononuclear group VIB metal tetracarbonyls [M(CO)₄{1-κ²P,N}] (M=Cr(2), Mo(3), W(4)). Complexes 2–4 were characterized by multinuclear NMR (¹H, ¹³C and ³¹P NMR) and IR spectroscopy, and their structures were also determined by single crystal X-ray diffraction. 2 and 4 represent the first examples of structurally characterized complexes of such ligands with group 6B metal carbonyls.