Versatile binding properties of a di-2-pyridyl ketone nicotinoylhydrazone ligand: Crystal structure of a Cu(II) complex

Six new copper complexes of di-2-pyridyl ketone nicotinoylhydrazone (HDKN) have been synthesized. The complexes have been characterized by a variety of spectroscopic techniques and the structure of [Cu(DKN)2]·H2O has been determined by single crystal X-ray diffraction. The compound [Cu(DKN)2]·H2O crystallized in the monoclinic space group P21 and has a distorted octahedral geometry. The IR spectra revealed the presence of variable modes of chelation for the investigated ligand. The EPR spectra of compounds [Cu2(DKN)2( -N3)2] and [Cu2(DKN)2( -NCS)2] in polycrystalline state suggest a dimeric structure as they exhibited a half field signal, which indicate the presence of a weak interaction between two Cu(II) ions in these complexes

Synthesis, spectral characterization and crystal structure of copper(II) complexes of 2-benzoylpyridine-N(4)-phenylsemicarbazone

An interesting series of nine new copper(II) complexes [Cu2L2(OAc)2] H2O (1), [CuLNCS] ½H2O (2), [CuLNO3] ½H2O (3), [Cu(HL)Cl2] H2O (4), [Cu2(HL)2(SO4)2] 4H2O (5), [CuLClO4] ½H2O (6), [CuLBr] 2H2O (7), [CuL2] H2O (8) and [CuLN3] CH3OH (9) of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on the EPR studies, spin Hamiltonian and bonding parameters have been calculated. The g values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the dx2 y2 orbital. The structure of the compound, [Cu2L2(OAc)2] (1a) has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed monoclinic space group P21/n. The coordination geometry about the copper(II) in 1a is distorted square pyramidal with one pyridine nitrogen atom, the imino nitrogen, enolate oxygen and acetate oxygen in the basal plane, an acetate oxygen form adjacent moiety occupies the apical position, serving as a bridge to form a centrosymmetric dimeric structure