Synthesis, crystal structures, thermal, and spectroscopic properties of four new metal(II) (M = Co, Ni, Cu, Hg) complexes of 2-benzoylbenzoate with 3-picoline

Four 2-benzoylbenzoate (bba) complexes, [Co(bba)(2)(H2O)(2)(3-pic)(2)] (1), [Ni(bba)(2)(H2O)(2)(3-pic)(2)] (2), [Cu(bba)(2)(3-pic)(2)] (3), and [Hg(bba)(2)(3-pic)(2)] (4), have been synthesized and characterized by IR spectra, thermal (TG, DTG, and DTA) analysis, and single crystal X-ray diffraction. All the complexes consist of neutral monomeric units with 1 and 2 crystallizing in the orthorhombic (P n a 2(1)), 3 in triclinic (P (1) over bar), and 4 in monoclinic (P2(1)/c) crystal systems. The metal(II) ions exhibit distorted octahedral coordination for 1, 2, and 3 and mercury(II) exhibits distorted trigonal prism coordination. In 1 and 2, bba is monodentate, whereas in 3 and 4 bba is bidentate. 3-Picoline (3-pic) is a classical N-monodentate ligand. Bba are coordinated to metal(II) with carboxylates and IR spectra of all complexes display characteristic absorptions of carboxylate {v(OCO)(asym) and v(OCO)(sym)}. Thermogravimetric (TG) analyses show that 1 and 2 are thermally stable (T-decomp.>60 degrees C) and 3 and 4 are thermally stable (T-decomp.>120 degrees C).