Synthesis and characterization of picolinate-containing nickel(II) complexes with tridentate and tripodal tetradentate ligands

Two picolinate-containing nickel(II) complexes Ni(bbma)(pic)(H₂O)]ClO₄ · CH₃OH (1) and Ni(ntb)(pic)]Cl · CH₃OH · 3H₂O (2) were synthesized and characterized by infrared, elemental analysis, UV-Vis, and X-ray diffraction analyses, where bbma is bis(benzimidazol-2-yl-methyl)amine, ntb is tris(2-benzimidazolylmethyl)amine, pic is the anion of picolinic acid. X-ray analysis shows that both complexes are mononuclear with picolinate coordinated to Ni(II) in a μ₂-N,O chelating mode. Both complexes adopt distorted octahedral geometry. Intermolecular N–H ··· O and O–H ··· O hydrogen bonds and π–π interactions in 1 and 2 are important in stabilization of the crystal structures.