Synthesis, spectroscopic, thermal and structural properties of benzimidazole containing some metal (II) crotonate complexes

In this work, [Co(crot)2(BIm)2] (1), [Cu(crot)2(BIm)2] (2), [Zn(crot)2(BIm)2] (3) and [Cd(crot)2(BIm)2] (4) complexes were synthesized by using crotonate as anionic ligand and benzimidazole (BIm) as neutral ligand. Composition of these complexes were determined by elemental analysis. Spectroscopic (IR and UV-Vis.), magnetic and thermal properties of complexes were investigated. 1, 2, 3 and 4 complexes were characterized by X-ray single crystal diffraction method. At room temperature spin only magnetic moments were calculated from the magnetic susceptibility measurement of complexes. Cu(II) and Co(II) complexes were found to be paramagnetic whereas Cd(II) and Zn(II) complexes were diamagnetic. Thermal decomposition behaviour of complexes were investigated by TG, DTG and DTA techniques. Thermal analysis datas show that complexes lose benzimidazole ligands in the first stage of decomposition and in the following stages crotonate ligands decompose to metaloxides all of the complexes. In the 1, 2, and 4 complexes, the crotonate acted as dianionic bidentate ligand bonded to the metals and in the 3 complex dentate ligand bonded to the metals, BIm ligand bonded to the metals via its ring nitrogen atoms. Coordination geometry of central atoms in the (1), (2), and (4) complexes were distorted octahedral, in the (3) complex was distorted tetrahedral.