First row transition metal complexes of bis(3,5-dimethyl pyrazolyl)methane: Synthesis, molecular structure and antibacterial properties

•A series of nine 3d transition metal complexes supported by bis(3,5-dimethylpyrazolyl)methane ligand is reported.•Molecular structure of the complexes was determined by various spectro-analytical techniques, including single crystal X-ray crystallographic studies.•Profound influence of the steric factors of the ligand substituent on the coordination chemistry and molecular structure of the complexes is profiled.•All the complexes were found to be bactericidal against the four bacterial stains tested, with the cobalt based complex being the best, however with high MIC/MBC values. A series of nine transition metal complexes was synthesized by reacting bis(3,5-dimethylpyrazolyl)methane (BP) with the respective metal chlorides in 1:1 and 2:1 stochiometric proportions. The complexes were duly characterized by molar conductivity measurement, IR, UV, NMR spectroscopy and elemental analysis. Using X-ray analysis, solid state molecular structures of the complexes C3 and C8 were determined. The molecular structures and the stoichiometry of the obtained complexes were found to be governed by the steric factors of the ligand substituents. The prepared compounds were found to be bactericidal against the four bacterial stains tested, however with high MIC/MBC values. [Display omitted]