Three new coordination complexes of cobalt(III), manganese(II), and copper(II) with N,N,O-donor hydrazone ligands: syntheses and structural characterizations

Three new coordination complexes, 2{[Co(L-1)(2)]ClO4} center dot A 0.5CH(3)OH (1), [Mn(L-2)(2)] (2), and [Cu(HL2)(L-2)]ClO4 center dot A 2H(2)O (3) have been synthesized from two tridentate N,N,O-donor hydrazone ligands HL1, 2-acetylpyridine-salicyloylhydrazone, and HL2, 2-benzoylpyridine-salicyloylhydrazone, respectively and thoroughly characterized by elemental analysis, FT-IR, UV-Vis, electrochemical, and room temperature magnetic susceptibility measurements. Structures of the complexes have been unequivocally established by single crystal X-ray diffraction technique. Structural analysis reveals that 1 consists of two chemically similar but crystallographically independent cationic [Co(L-1)(2)](+) units and 2 consists of a neutral [Mn(L-2)(2)] molecule while 3 consists of a cationic [Cu(HL2)(L-2)](+) unit. Metal ions display distorted octahedral geometry in 1 and 2 while in 3 it shows a distorted square pyramidal geometry. Ligand conformations around the metal ions are stabilized by the presence of intra-ligand hydrogen bonding in all the complexes. Structure of 3 reveals that a perchlorate ion linked to the complex by hydrogen bonding via a water molecule.