FT-IR and theoretical study of 3,5-dimethyl-1H-pyrazole-1-carboxamidine (L) and the complexes CoL2(H2O)2(NO3)2, NiL2(H2O)2(NO3)2

In the paper a joint experimental and theoretical study of 3,5-dimethyl-1H-pyrazole-1-carboxamidine (L) as well as its complexes CoL2(H2O)2(NO3)2 and NiL2(H2O)2(NO3)2 is reported. On the basis of FT-IR experiments and a DFT-derived scaled quantum mechanical force field the normal coordinate analysis of L was carried out. The FT-IR spectra of the two complexes were interpreted using the present assignment of L and computed vibrational data of the complexes. The ionic and charge transfer interactions in the complexes were assessed by means of natural bond orbital (NBO) analysis.

Synthesis, spectroscopic and X-ray characterization of a copper(II) complex with the Schiff base derived from pyridoxal and aminoguanidine: NMR spectral studies of the ligand

A copper(II) complex with the pyridoxal-aminoguanidine (PL-AG) Schiff base adduct, as an organic compound of the very potent biological activity and promising pharmacological importance in the treatment of diabetic complications, has been prepared and characterized. The X-ray structural analysis of the [CuCl2(PL-AG)] complex showed that it has a distorted pseudo-square-pyramidal (4+1) structure with the tridentate ONN Schiff base in the equatorial plane, with the Cu-O(1), Cu-N(1) and Cu-N(3) bond lengths of 1.917(2)A, 1.930(2)A and 1.984(2)A, respectively. The bond length of the equatorial Cu-Cl(1) is 2.279(1)A, while that of the apical Cu-Cl(2) is 2.792(1)A. Pyridoxal fragment is coordinated in its zwitterionic form. In addition to the X-ray structural analysis, the complex was characterized by IR spectrometric, conductometric and magnetic techniques, and the ligand itself by IR, 1H and 13C NMR spectra.

Copper(II) Complexes with Reduced Schiff Base: Synthesis, Spectroscopic, Thermal, X-Ray, and Cytotoxic Studies of Novel Copper(II) Complexes with an Arylpyrazole Ligand

The synthesis of a novel arylpyrazole-derived ligand, 1,2-bis[(1,3-diphenylpyrazol-4-yl)methyl]diaminoethane (Ph4Pz2mde), and its complexes prepared with CuCl2 [Cu(Ph4Pz2mde)Cl2(MeOH)] 1, CuBr2 [Cu(Ph4Pz2mde)Br2(MeOH)] 2, from MeOH, and [Cu(Ph4Pz2mde)Cl2(DMF)] 3, from a mixture of MeOH and DMF, are described. The complexes are characterized by elemental and thermal analysis and FT-IR spectroscopy, while the 1H and 13C NMR assignments are given for the ligand. The crystal and molecular structure of [Cu(Ph4Pz2mde)Cl2(DMF)] was determined by single-crystal X-ray diffraction. In-vitro cytotoxicity of the Ph4Pz2mde ligand and two copper(ii) complexes was obtained using sulforhodamine B (SRB) treatment against three human tumour cell lines: HeLa (epitheloid carcinoma of cervix), MCF-7 (breast adenocarcinoma), and MRC-5 (lung fetal fibroblasts).

Transition metal complexes with thiosemicarbazide-based ligands. LIII. [4-(2-Diphenylphosphino-α-ethoxybenzyl-κP)-S-methyl-1-(4-oxidopent-3-en-4-ylidene-κO)thiosemicarbazido-κ2N1,N4]nickel(II)

The title compound, [Ni(C(28)H(30)N(3)O(2)PS)], crystallizes with two independent molecules in the asymmetric unit. The Ni(II) atoms are in significantly deformed square-planar environments formed by an ONNP donor set from a thiosemicarbazide-based tetradentate ligand. The Ni(II) atom and the ONN donor atoms are nearly coplanar, while the P atom deviates from their mean planes by 0.278 (4) and 0.202 (4) Angstrom for the two independent molecules. The P-containing chelate rings are remarkably non-planar, adopting a boat conformation, which is unusual for chelate rings in transition metal complexes with thiosemicarbazide-based tetradentate ligands. The orientation of the ethoxy group bonded to this chelate ring is caused by an intramolecular C-H...pi interaction with the opposing phenyl ring. There are no hydrogen bonds; instead, numerous intermolecular C-H...pi interactions dominate in the crystal packing.

Transition metal complexes with pyrazole-based ligands. XXII. Di-μ-thiocyanato-bis[(3,5-dimethyl-1H-pyrazole-1-carboxamidine-κ2N,N′)(thiocyanato-κN)copper(II)] and a redetermination of bis(3,5-dimethyl-1H-pyrazole-1-carboxamidine-κ2N,N′)bis(nitrato-κO)copper(II)

The title Cu(II) complex, [Cu2(NCS)4(C6H10N4)2], represents the first crystal structure of a polynuclear transition metal complex with the 3,5-dimethyl-1H-pyrazole-1-carboxamidine ligand (HL). It is compared with previously reported crystal structures of metal complexes with the same HL ligand. The molecule contains an eight-membered binuclear Cu2(NCS)2 ring, which is centrosymmetric and in a chair conformation. The Cu atom has a distorted square-pyramidal geometry with a very elongated Cu-S bond of 2.993 (2) A. The crystal structure redetermination of the bis(3,5-dimethyl-1H-pyrazole-1-carboxamidine-kappa(2)N,N')bis(nitrato-kappaO)copper(II)complex, [Cu(NO3)2(C6H10N4)2], and analysis of its hydrogen bonds confirm the significance of the NO3 groups in the formation of a three-dimensional hydrogen-bonding network. Both complexes are centrosymmetric, the inversion centre being located at the mid-point of the Cu...Cu line in (I) and the Cu atom being located at the inversion centre in (II).