Prathapachandra Kurup, M R; Sheeja, S R; Sarika, Sivakumar; Neema, Ani Mangalam; Edward, R T Tiekink(Elsevier, June 23, 2009)
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Abstract:
Four hydrazone ligands: 2-benzoylpyridine benzoyl hydrazone (HBPB), di-2-pyridyl ketone nicotinoyl
hydrazone (HDKN), quinoline-2-carbaldehyde benzoyl hydrazone (HQCB), and quinoline-2-carbaldehyde
nicotinoyl hydrazone (HQCN) and four of their complexes with vanadyl salts have been synthesized and
characterized. Single crystals of HBPB and complexes [VO(BPB)(l2-O)]2 (1) and [VO(DKN)(l2-O)]2 ½H2O
(2) were isolated and characterized by X-ray crystallography. Each of the complexes exhibits a binuclear
structure where two vanadium(V) atoms are bridged by two oxygen atoms to form distorted octahedral
structures within cis-N2O4 donor sets. In most complexes, the uninegative anions function as tridentate
ligands, coordinating through the pyridyl- and azomethine-nitrogen atoms and enolic oxygen whereas in
complex [VO(HQCN)(SO4)]SO4 4H2O (4) the ligand is coordinated in the keto form. Complexes [VO(QCB)(
OMe)] 1.5H2O (3) and 4 are found to be EPR active and showed well-resolved axial anisotropy with
two sets of eight line pattern
Prathapachandra Kurup, M R; Sheeja, S R; Neema, Ani Mangalam(Elsevier, 2010)
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Abstract:
Mn(II) complexes derived from a set of acylhydrazones were synthesised and characterized by elemental
analyzes, IR, UV–vis and X-band EPR spectral studies as well as conductivity and magnetic susceptibility
measurements. In the reported complexes, the hydrazones exist either in the keto or enolate form, as evidenced
by IR spectral data. Crystal structures of two complexes are well established using single crystal
X-ray diffraction studies. In both of these complexes two equivalent monoanionic ligands are coordinated
in a meridional fashion using cis pyridyl, trans azomethine nitrogen and cis enolate oxygen atoms positioned
very nearly perpendicular to each other. EPR spectra in DMF solutions at 77 K show hyperfine sextets
and in some of the complexes the low intensity forbidden lines lying between each of the two
hyperfine lines are also observed
Prathapachandra Kurup, M R; Neema, Ani Mangalam(Elsevier, 2011)
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Abstract:
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