Synthesis and characterization of nicotinamide coordinated metal carbonyl complexes

2260-2267Three new nicotinamide coordinated group VI B metal carbonyl complexes fac-[M(CO)3(nicotinamide)3] (M = Cr, Mo, and W; 4, 5, and 6) (nicotinamide = 3-H2NOCC5H4N) have been synthesized. Reaction of the in situ generated complex precursors fac-[M(CO)3 (CH3CN) 3] (M = Cr, Mo, and W; 1, 2, and 3) with three equivalents of nicotinamide in methanol at room temperature give nicotinamide coordinated metal carbonyl complexes 4, 5, andd 6 in good yields. The complexes exhibit two bands corresponding to v(C=O) of metal carbonyl groups and v(C=O) of nicotinamide ligands. Ali the complexes ex hi bit a very strong stretching band corresponding to v(C=O) of coordinated nicotinamide ligands at 1684 (Cr, 4); 1669 (Mo, 5): and 1683 cm-1 (W, 6). The occurrence of single v(C=O) band suggests the coordination of three nicotinamide molecules that are arranged cis to each other and representing a C3v configuration of ligands around the metal atom in the facial geometry of the complexes. The 1H NMR spectra of the complexes shows signals at four different chemical shirt regions, corresponding to the four protons on the pyridine ring of the nicotinamide ligand . The calculated integral value of each signal is present in the ratio 1:1:2:2. The powder X-ray diffractogram of the complexes exhibit similar pattern suggesting the similar arrangements of atoms in the crystal lattice and geometry