Transition metal complexes with a new tridentate ligand, 5-[6-(5-mercapto-1,3,4-oxadiazol-2-yl)pyridin-2-yl]-1,3,4-oxadiazole-2-thiol

A new ligand 5-[6-(5-mercapto-1,3,4-oxadiazol-2-yl)pyridin-2-yl]-1,3,4-oxadiazole-2-thiol (L) and its Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes were synthesized. The authenticity of the ligand and its transition metal complexes were established by elemental analyses, conductance and magnetic susceptibility measurements, as well as spectroscopic (IR, 1H- and 13C-NMR, electronic, mass, ESR) and thermal studies. The IR and 1H-NMR spectral studies revealed the existence of the ligand in the thiol form in the solid state, whereas in the thione form in the dissolved state. The magnetic and electronic spectral studies suggest an octahedral geometry for all the complexes. The ligand acts as a tridentate ligand coordinating through the pyridine nitrogen and the nitrogen atoms (N-3' and N-3'') of the two oxadiazole rings. Antimicrobial screening of the ligand and its metal complexes were determined against the bacteria Escherichia coli and Bacillus cirroflagellosus, as well as against the fungi, Aspergillus niger and Candida albicans

Crystal structure of 3-acetylcoumarin-o-aminobenzoylhydrazone and synthesis, spectral and thermal studies of its transition metal complexes

Transition metal [Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)] complexes of a new Schiff base, 3-acetylcoumarin-o-aminobenzoylhydrazone were synthesized and characterized by elemental analyses, magnetic moments, conductivity measurements, spectral [Electronic, IR, H-1 and C-13 NMR, EPR] and thermal studies. The ligand crystallizes in the monoclinic system, space group P2(1)/n with a = 9.201(5), b = 16.596( 9), c = 11.517(6) angstrom, beta= 101.388(9)degrees, V = 1724.2 (17) angstrom(3) and Z = 4. Conductivity measurements indicated Mn(II) and Co(II) complexes to be 1 : 1 electrolytes whereas Ni(II), Cu(II), Zn(II) and Cd(II) complexes are non-electrolytes. Electronic spectra reveal that all the complexes possess four-coordinate geometry around the metal

Crystal Structure of 2-pyridine-2-yl-3(pyridine-2-carboxylideneamino)quinazolin-4(3h)-one and its Ligating Diversity Towards Transition Metal(II) Ions

The synthesis of a new ligand 2-pyridine-2-yl-3(pyridine-2-carboxylideneamino)-quinazolin-4(3H)-one (PPCAQ) is described together with its manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes. The single crystal X-ray diffraction studies of the ligand reveal the presence of two crystallographically independent molecules in asymmetric unit cell, which exhibit N...N attractive interaction. The PPCAQ and its metal complexes were characterized by analytical, spectroscopic (i.r., n.m.r and u.v.-vis), magnetic moment, conductance and thermal studies. The i.r. spectral studies reveal the ligational diversity of the PPCAQ towards different metal ions as NNN donor in cobalt(II), copper(II), zinc(II) and cadmium(II) complexes and as ONN donor in manganese(II) and nickel(II) complexes. The antimicrobial activity of all the compounds was tested; copper(II), zinc(II) and cadmium(II) complexes show enhanced antibacterial activity compared to the free ligand

Transition metal complexes of a tridentate ligand bearing two pendant pyridine bases: The X-ray crystal structure of pentacoordinate copper(II) complex

The synthesis of a tridentate ligand,N,N'-bis(2-pyridinyl)-2,6-pyridinedicarboxamide [H2L] is described together with its manganese(II), cobalt(II), nickel(II), copper(II),zinc(II) and cadmium(II) complexes which were characterized based on elemental analysis, conductivity measurements, spectral, magnetic and thermal studies. The IR spectral studies of all the complexes exhibit a similar feature about the ligating nature of the ligand to the metalions and revealed that the ligand has coordinated through the nitrogens of the deprotonated amides and the central pyridine. The two pendant pyridine nitrogens in all the complexes are protonated and involved in hydrogen bonding with the oxygens of amide groups. This observation is confirmed by the single-crystal X-ray crystallographic studies of copper(H) complex. The geometry around the copper atom can be viewed as a distorted trigonal bipyramid with \tau = 0.74 [structural parameter,\tau = (\beta - \alpha)/60; where \alpha and \beta are the two basal angles in a five coordinate complex]. The electro chemical study of the copper(II) complex shows single quasi-reversible redox peak [Cu(II) <->Cu(l)]. The EPR spectrum of copper(H) complex exhibits rhombic pattern $[g_{1} = 2.0276, g_{2} = 2.0926 and g_{3} = 2.18]$

Synthesis and spectral studies of Cu(II), Ni(II), Co(II), Mn(II), Zn(II) and Cd(II) complexes of a new macroacyclic ligand N,N’-bis(2-benzothiazolyl)-2,6-pyridinedicarboxamide

A new macroacyclic amide ligand N,N’-bis(2-benzothiazolyl)-2,6-pyridinedicarboxamide (BPD), formed by the condensation of 2,6-pyridinedicarbonyldichloride with 2-aminobenzothiazole, and its Cu(II), Ni(II), Co(II), Mn(II), Zn(II) and Cd(II) complexes were synthesized. Their structures were elucidated on the basis of elemental analyses, conductance measurements, magnetic moments, spectral (IR, NMR, UV-Visible, EPR and FAB) and thermal studies. The complexes exhibit an octahedral geometry around the metal center. Conductance data of the complexes suggested them to be 1:1 electrolytes. The pentadentate behavior of the ligand was proposed on the basis of spectral studies. The X-band EPR spectra of the Cu(II) and Mn(II) complexes in the polycrystalline state at room (300 K) and liquid nitrogen temperature (77 K) were recorded and their salient features are reported

Crystal Structure of 2-pyridine-2-yl-3(pyridine-2-carboxylideneamino)quinazolin-4(3h)-one and its Ligating Diversity Towards Transition Metal(II) Ions

The synthesis of a new ligand 2-pyridine-2-yl-3(pyridine-2-carboxylideneamino)-quinazolin-4(3H)-one (PPCAQ) is described together with its manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes. The single crystal X-ray diffraction studies of the ligand reveal the presence of two crystallographically independent molecules in asymmetric unit cell, which exhibit N...N attractive interaction. The PPCAQ and its metal complexes were characterized by analytical, spectroscopic (i.r., n.m.r and u.v.-vis), magnetic moment, conductance and thermal studies. The i.r. spectral studies reveal the ligational diversity of the PPCAQ towards different metal ions as NNN donor in cobalt(II), copper(II), zinc(II) and cadmium(II) complexes and as ONN donor in manganese(II) and nickel(II) complexes. The antimicrobial activity of all the compounds was tested; copper(II), zinc(II) and cadmium(II) complexes show enhanced antibacterial activity compared to the free ligand

X-ray crystal structure of phenylglycine hydrazide: Synthesis and spectroscopic studies of its transition metal complexes

Phenylglycine hydrazide was synthesized and investigated by X-ray crystallography. It crystallizes in the monoclinic space group P121/c with cell parameters a = 5.9459 (18) \AA, b = 5.1940 (16) \AA, c = 26.7793 (83) \AA and Z = 2. Its conformational changes, on complexation with transition metal ions Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) has been studied on the basis of elemental analysis, magnetic moment and spectral (IR, $^1H$ NMR, UV–vis) studies. The bidentate nature of the ligand was confirmed on the basis of a comparative IR and NMR spectral studies. The trigonal bipyramidal geometries were observed for Cu(II), Ni(II) and Co(II) complexes, while it is octahedral for the remaining complexes. The conductivity data suggest them to be non-electrolytes