The influence of the pyridyl substituent in N-methyl-P,P-diphenyl-N-2-pyridinyl-phosphinous amide ligand on the coordination chemistry of group 6B metal carbonyl derivatives

The reaction of N-methyl-P,P-diphenyl-N-2-pyridinyl-phosphinous amide (1) with group 6B metal hexa, tetra, and tricarbonyls yielded the same octahedral complexes cis-M(CO)₄[1-κ²P,N^py] (M = Cr(2), Mo(3), W(4)) in which the ligand chelates only in a bidentate fashion through its phosphorus atom and pyridyl N-atom. Compounds 1–4 were identified and characterized by multinuclear NMR spectroscopy (¹H, ¹³C, ³¹P NMR), elemental analysis, IR and UV–Vis spectroscopy. Complexes 2–4 exhibited weak metal-to-ligand charge transfer transitions unaffected by solvent polarity. Crystal structure determination is carried out on complex 4.