Synthesis, Crystal Structure, Thermal Behavior and IR Characterization of Pentacarbonyl(4-methylpyridine)chromium(0) Complex

Pentacarbonyl(4-methylpyridine)chromium(0) complex was isolated from n-hexane solution as yellow plate-like crystals and characterized by using X-ray crystallography. It crystallizes in the orthorhombic system with the space group Cmcm and Z = 4. The unit cell parameters are a = 11.737(1) A, b = 12.857(2) A, c = 8.465(1) A. The single crystal X-ray structure of the complex shows that the coordination sphere around the chromium central atom is slightly distorted octahedron, involving the 4-methylpyridine (4-mp), ligand as a monodentate N-donor ligand and five carbonyl groups. The four equatorial CO groups in the complex, with the Cr–C2 distance of 1.886 Ǻ, are slightly bent away from the 4-methylpyridine ligand with the N–Cr–C2 angle of 91.69°. The pyridine ring plane makes an angle of 135.17° with the Cr–N–CO bond axis. The thermal analysis (differential thermal analysis and thermal gravimetry) and IR spectra of the complex indicated that the compound undergoes complete decomposition to form the Cr2O3 as the final decomposition product. The crystal structure of pentacarbonyl(4-methylpyridine)chromium(0) complex has been determined and its thermal behavior has also been studied.