Munesh Kumar

Metal Complexes of 2,6-Diacetylpyridine Bis(thiosemicarbazone): their Preparation, Characterization and Antitumour Activity

Complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Pt(II) with 2.6-diacetylpyridine bis(thiosemicarbazone) (daptsc-H2) have been isolated and characterized by elemental analysis, conductance measurements, magnetic susceptibilities (from room temperature to liquid nitrogen temperature), diffuse reflectance and infrared studies. On the basis of these studies a seven-coordinate structure for Zn(daptsc-H2)(OAc)2, a six-coordinate structure for M(daptsc-H2)Cl2 (MMn(II), Co(Il), Ni(II) or Cu(II)) and Fe(daptsc-H2)SO4, and a five-coordinate structure for Pt(daptsc) are suggested. 57Fe Mossbauer spectra at 300 and 78 K also suggest a distorted octahedral structure with dxy ground state for Fe(daptsc-H2)SO4 complex. All these metal(II) complexes have been screened for their antitumour activity in the P388 lymphocytic leukaemia test system in mice and showed enhanced antitumour activity relative to the free ligand.

Synthesis, characterization and antitumor activity of manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and platinum(II) complexes of 3- and 5-substituted salicylaldehyde benzoylhydrazones

Abstract Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Pt(II) with 3- and 5-substituted salicylaldehyde benzoylhydrazones (XSBH, X = H, 3-NO 2 , 3-CH 3 O, 5-Br, 5-Cl, 5-CH 3 or 5-NO 2 ) were prepared and characterized by elemental analyses, conductance measurements, magnetic moments (300−78 K) and spectral studies. On the basis of these studies the following structures are suggested: distorted octahedral for Mn(XSBH) 2 , dimeric, low-spin, five- coordinate for Ni(XSBH)Cl·2H 2 O, dimeric, high-spin, five-coordinate for Co(XSBH)Cl·2H 2 O, dimeric four- coordinate for Zn(XSBH) and a square-planar structure for M(XSBH)Cl·H 2 O (M = Cu(II) or Pt(II)). The polycrystalline ESR spectra of Cu(II) complexes are isotropic and indicate a d x 2− y 2 ground state in square-planar stereochemistry. All the metal(II) complexes were screened for their antitumor activity against the P388 lymphocytic leukaemia test system in mice and were found to possess no significant activity at the dosages used.

Synthesis, characterization and antitumour activity of iron(II) and iron(IlI) complexes of 3- and 5-substituted salicylaldehyde benzoyl hydrazones

Abstract Iron(II) and iron(III) complexes of tridentate ligands derived from various substituted salicylaldehydes and benzoyl hydrazones have been prepared and characterized by elemental analysis, conductance measurements, magnetic susceptibilities (from room temperature down to liquid N2 temperature), and Mossbauer, electronic and infrared spectral studies. On the basis of these studies the following structures are suggested: monomeric, high-spin, five-coordinate for Fe(XSBH)SO4·H2O (XSBH = substituted salicylaldehyde benzoyl hydrazone, X = H, 3-CH3O, 3-NO2, 5-Cl, 5-Br, 5-CH3 or 5-NO2); dimeric, high-spin, phenoxide bridged, five-coordinate for Fe(H-SBH)Cl (H-SBH = salicylaldehyde benzoyl hydrazone); and monomeric, high-spin, six-coordinate for Fe(XSBH) Cl2·H2O (X = 3-CH3O, 3-NO2, 5-Cl, 5-Br, 5-CH3 or 5-NO2). Intermolecular antiferromagnetic exchange interaction is present in the dimeric Fe(XSBH)Cl complex, where the exchange parameter is −7.3 cm−1. The complex exhibits an asymmetrical quadrupole-split doublet in its 57Fe Mossbauer spectra. The asymmetry is found to be temperature dependent with a relatively symmetrical doublet at low temperature. All these complexes have been screened for their antitumour activity against the P388 lymphocytic leukaemia test system in mice and have been found to possess no significant activity at the dosages employed.

Synthesis, characterization and antitumor activity of some metal complexes of 3- and 5-substituted salicylaldehyde o-hydroxybenzoylhydrazones

Abstract Complexes of Mn(II), Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Pt(II) with 3- and 5-substituted salicylaldehyde o -hydroxybenzoylhydrazones (XSBH, X = H, 3-NO 2 , 3-CH 3 O, 5-Cl, 5-Br, 5-CH 3 or 5-NO 2 ) have been prepared and characterized by elemental analysis, conductance measurements, magnetic susceptibilities (from room temperature down to liquid nitrogen temperature) and spectral studies. These studies indicate the following structures: monomeric, high-spin, distorted octahedral for Mn(XSBH) 2 ; monomeric, high-spin, five-coordinate for Fe(XSBH)SO 4 ·H 2 O; dimeric, high-spin phenoxide bridged, five-coordinate for Fe(XSBH)Cl; dimeric, high-spin five-coordinate for Co(XSBH)Cl·2H 2 O; dimeric low-spin, five-coordinate for Ni(XSBH)Cl·2H 2 O; dimeric, four-coordinate for Zn(XSBH); and a square-planar structure for M(XSBH)Cl·H 2 O (M = Cu(II) or Pt(II). Intermolecular antiferromagnetic exchange interactions are present in Fe(III) complexes, where the exchange parameter ( J ) is ca . −8.0 cm −1 for these complexes. The Fe(III) complexes exhibit asymmetric quadrupole split doublets in their 57 Fe Mossbauer spectra. The asymmetry is found to be temperature dependent with relatively symmetrical doublets seen at low temperature. The polycrystalline ESR spectra of Cu(II) complexes are isotropic and indicate a d x 2 −y 2 ground state in square-planar stereo-chemistry. All these metal complexes have been screened for their antitumor activity against the P 388 lymphocytic leukaemia test system in mice and enhanced antitumor activity relative to the free ligand was found but no significant activity at the dosages used.

Transition metal chemistry of oxime — Containing ligands, Part XXVIII; manganese(II) complexes of 2,6-diacetylpyridine dioxime

SummaryComplexes of manganese(II) with the tridentate oxime ligand 2,6-diacetylpyridine dioxime (H2dapd) have been synthesized and characterized. The complexes [Mn(H2dapd)X2] are pentacoordinate for X = Cl, Br or I but apparently octahedralvia bridging anions for X = NCS or NCSe. The complex [Mn(H2dapd)(NO3)2] adopts an octahedral structure involving monodentate and bidentate coordination of nitro groups. The complexes [Mn(H2dapd)2]X2 (X = Cl, Br, I, NO3, NCS or NCSe) involve an octahedral cation.

Synthesis, magnetic and electrochemical properties of binuclear copper(II) complexes of pyridoxal hydrazones

Abstract Some new binuclear copper(II) complexes with pyridoxal benzoylhydrazone (PBH), pyridoxal o-hydroxylbenzoyl- hydrazone (PHBH), pyridoxal picolinoylhydrazone (PPH), pyridoxal nicotinoylhydrazone (PNH), and pyridoxal isonicotinoylhydrazone (PINH) have been synthesized and characterized by analytical, magnetic, spectral, ESR and electrochemical methods. All the complexes exhibit normal magnetic moments at room temperature. The variable temperature magnetic moments, however, indicate the presence of very weak intramolecular antiferro- magnetic interactions (−2J ≈~90 cm−1) in between the copper(II) centers in the complexes. The ESR spectral data at 77 K are characteristic of binuclear CuCu complexes and exhibit a seven-line pattern in the low field gl region. The cyclic voltammograms of each complex showed two oxidation waves attributed to Cu2II,II→Cu2II,III and Cu2II,III→Cu2III,III processes at significantly low potentials.

Transition-metal chemistry of oxime-containing ligands—XXVII. Five- and six-coordinate complexes of iron(II) and iron(III) with 2,6-diacetylpyridine

Abstract Iron(II) and iron(III) complexes of 2,6-diacetylpyridine dioxime (H2dapd) have been prepared and their electronic and structural properties investi

Transition Metal Chemistry of Oxime Containing Ligands. Part XXVII. Nickel(II) Complexes of 2,6-Diacetylpyridine Dioxime

Abstract The synthesis and characterization (by elemental analysis, magnetic measurements and spectral studies) of 1:1 and 1:2 nickel(II) complexes of 2,6-diacetylpyridine dioxime (H2dapd) are reported. The complexee [Ni(H2)(X2))] are pentacoordinate for x = C1− Br− or I− but apparently octahedral via bridging anions for X = NCS− or NCSe−. The complex [Ni(H2dapd)(NO3)2] adopts an octahedral structure involving monodentate and bidentate coordination of nitro groups. The complexes [Ni(H2dapd)2](X)2, (X = Cl−, Br−, I−, NO3, NCS− or NCSe−) involve an octahedral cation.

Unusual redox and chemical properties of N4-substituted pyridoxal thiosemicarbazone copper(II) complexes: their preparation, properties and reactivities

SummaryNew copper(II) complexes with pyridoxal N4-methylthiosemicarbazone (H2Methsa), N4-ethylthiosemicarbazone (H2Etthsa) and N4-phenylthiosemicarbazone (H2Phthsa) have been prepared and characterized by analytical, magnetic, spectral, e.s.r. and electrochemical methods. All the compounds exhibit normal magnetic moments at room temperature. The variable temperature magnetic moments, however, show the presence of very weak intramolecular antiferromagnetic interaction (−2J = ca. 30cm-1) between the copper(II) centres in the complexes. The e.s.r. spectra at 77 K in DMSO indicate the presence of a mixture of monomers and dimers consistent with the dissociation of the complexes. Electrochemical studies in non-aqueous solvents show that the complexes undergo a quasi-reversible one electron facile reduction at markedly low negative potentials versus saturated calomel electrode (s.c.e.).

Transition Metal Chemistry of Oxime Containing Ligands. XXVI. Spectral and Magnetic Properties of Nickel(II) Complexes of Quinoline-2-aldoxime and Isoquinoline-3-aldoxime

Abstract The complexes of the types [Ni(HL)2(X)2] (HL = quinoline-2-aldoxime(Hqox) or isoquinoline-3-aldoxime(Hiqox) and X = Cl−, Br−, I−, NCS−, NCSe−, OAc− or 1/2 SO− 2) and [Ni(HL)2(NO3)](NO3) (HL = Hqox or Hiqox) have been synthesized and characterized on the basis of elemental analysis, molar conductance, molecular weight determination, X-ray powder diffraction patterns, magnetic susceptibility data (300 to 78°K), diffuse reflectance and infrared spectral measurements. These physical studies suggest a dimeric halo-bridged cis- octahedral structure for halo complexes and a monomeric cis- octahedral structure for the remaining complexes.