The preparation and characterization of some new nickel(II), copper(II), zinc(II) and cadmium(II) complexes of the pyrrole-2-carboxaldehyde Schiff bases ofS-alkyl esters of dithiocarbazic acid

Summary New complexes of general formulae [Ni(HL)₂], [ML]·H₂O and [Cu(HL)X] (H₂L = pyrrole-2-aldehyde Schiff bases ofS-methyl- andS-benzyldithiocarbazates; X = Cl or Br; M = Ni^II, Cu^II, Zn^II or Cd^II) were prepared and characterized by a variety of physicochemical techniques. The Schiff bases coordinate as NS bidentate chelating agents in [Ni(HL)₂] and [Cu(HL)X], and as tridentate NNS chelates in [ML] (M = Ni^II, Cu^II, Zn^II or Cd^II). Both the [Ni(HL)₂] and [NiL] complexes are diamagnetic and square-planar. Based on magnetic and spectroscopic evidence, thiolate sulphur-bridged dimeric square-planar structures are assigned to the [Cu(HL)X] and [ML] (M = Ni^II or Cu^II) complexes. The complexes ML (M = Zn^II or Cd^II) are polymeric and octahedral.     

Synthesis and chemical characterization of biologically important complexes of vanillin thiosemicarbazone with manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), and mercury(II)

Summary Vanillin thiosemicarbazone (VTSC) has been used to isolate the complexes of the types [M(VTSC)₂(H₂O)₂]X₂ (M=Mn^II, Fe^II, Co^II, or Ni^II and X=Cl) and [M(VTSC)X₂]H₂O (M=Cu^II, Zn^II, Cd^II or Hg^II and X=Cl). Probable structures of these complexes are suggested on the basis of elemental analysis, molar conductance, magnetic moment and electronic and i.r. spectral data. The fungicidal activity of VTSC and the isolated complexes has been evaluated on pathogenic fungi,Alternaria (Sp.),Paecilomyces (Sp.) andPestalotia (Sp.).On leave from the University of Myosore.     

Cobalt(II), nickel(II) and copper(II) complexes withN-cyano-N′-methyl-N″(2-[(5-methyl-1H-imidazol-4-yl)methylthio]ethyl)guanidine

Summary N-Cyano-N-methyl-N(2-[(5-methyl-1H-imidazol-4-yl)-methylthio] ethyl) guanidine cimetidine (CM), complexes with Co^II, Ni^II and Cu^II are described. The compounds are of stoichiometry [M(CM)₂]SO₄ · nH₂O [M = Co^II, Ni^II or Cu^II; n = 3,3 or 4, respectively], [M(CM)₂](ClO₄)₂ [M = Co^II or Ni^II], [M(CM)₂]Cl₂ · nH₂O [M=Co^II, Ni^II or Cu^II; n = 1, 2, or 2, respectively] and [Cu(CM)SO₄] · 2H₂O. The electronic spectra of the compounds in solid state, magnetic susceptibilities and i.r. and e.p.r. spectra were studied. Octahedral environments are proposed for the complexes: [M(CM)₂]SO₄·nH₂O, [M(CM)₂](ClO₄)₂, [Ni(CM)₂]Cl₂ · 2H₂O, [Cu(CM)₂]Cl₂ · 2H₂O and [Cu(CM)SO₄] · 2H₂O and a tetrahedral structure for [Co(CM)₂]Cl₂ · H₂O.     

Complexes of NS and NSO donor ligands. Nickel(II), copper(II) and cobalt(II) complexes of glyoxal bis(morpholineN-thiohydrazone) and diacetyl bis(morpholineN-thiohydrazone)

Summary Reactions of glyoxal bis(morpholineN-thiohydrazone), H₂gbmth, with NiCl₂·6H₂O, Ni(OAc)₂·4H₂O, Ni(acac)₂· H₂O, CuCl₂·2H₂O, Cu(OAc)₂·H₂O, Cu(acac)₂, CoCl₂· 6H₂O, Co(OAc)₂·4H₂O and Co(acac)₂·2H₂O yield complexes of the type [M(gbmth)], [M=Ni^II, Cu^II or Co^II]. Diacetyl reacts with morpholineN-thiohydrazide in the presence of nickel salts to yield [Ni^II(dbmth)], [Ni^II(dmth)(OAc)]H₂O and [Ni^II(Hdmth)(NH₃)Cl₂] involving N₂S₂ and NSO donor ligands. Copper and cobalt complexes of N₂S₂ and NSO donor ligands with compositions [Cu^II(dbmth)], [Co^II(dbmth)]·4H₂O and [Co^II(H₂dbmth)]Cl₂, have been isolated. The compounds have been characterised by elemental analyses, magnetic moments, molar conductance values and spectroscopic (electronic and infrared) data.     

Studies on 2-acetylthiophene-2-furoylhydrazone complexes of 3d-bivalent metal ions

Summary Metal(II) complexes of 2-acetylthiophene-2-furoylhydrazone (HL) of the types [VO(HL)SO₄], [Cu(HL)₂Cl₂(H₂O)], [M(HL)₂Cl₂] [M=Co^II, Ni^II, or Zn^II] and [ML₂(H₂O)₂] [M=Co^II, Ni^II, Cu^II or Zn^II] have been prepared and characterized on the basis of elemental analyses, molar conductance, magnetic susceptibility, visible, e.s.r. and i.r. spectral studies. The bonding and stereochemistry of the complexes are discussed.     

Transition metal complexes with thiosemicarbazide-based ligands,Part II,Synthesis and characterisation of nickel(II), cobalt(II), manganese(II) and zinc(II) complexes with the pentadentate ligand, 2,6-diacetylpyridine bis(S-methylisothiosemicarbazone)

Summary The reaction of warm alcoholic solutions of acetates of Co^II, Mn^II, Zn^II and Ni^II with 2, 6-diacetylpyridine andS-methylisothiosemicarbazide hydrogen iodide yielded the complexes: [Co(H₂L)I₂]·H₂O, [Mn(H₂L)(MeOH)₂]I₂, [Zn(H₂L)(MeOH)I]I and [Ni(HL)]I, (H₂L=the pentadentate pentaaza-ligand 2, 6-diacetylpyridine bis(S-methylisothiosemicarbazone)). The reaction of methanolic solutions of [Ni(HL)]I and NH₄NCS or LiOAc.2H₂O, give [Ni(HL)]NCS and NiL, respectively. For the complexes of Co^II, Mn^II and Zn^II, a pentagonal bipyramidal configuration is proposed, with H₂L in the equatorial plane and two unidentate ligands (I and/or MeOH) in the axial positions. The complexes [Ni(HL)]X (X=I or NCS) and NiL probably have monomeric five- and dimeric six-coordinate structures, respectively, in which only the chelate ligand is involved in coordination.     

The coordination chemistry ofN,N′-ethylenebis(2-acetylpyridine imine) andN,N′-ethylenebis(2-benzoylpyridine imine); two potentially tetradentate ligands containing four nitrogen atoms

Summary New complexes of the general formulae [ML_A(H₂O)₂]-Cl₂ (M=Ni or Cu), [ML_AX₂] (M=Co or Cu; X=Cl or Br), [NiL_ABr₂]·H₂O, [ML_A] [MCl₄] (M=Pd or Pt), [NiL_B(H₂O)₂]Cl₂·2H₂O, [ML_BCl₂] (M=Co, Ni, Cu, Pd or Pt; X=Cl or Br) and [ML_B] [MCl₄] (M=Pd or Pt), where L_A=N,N-ethylenebis(2-acetylpyridine imine) and L_B=N, N-ethylenebis(2-benzoylpyridine imine), have been isolated. The complexes were characterized by elemental analyses, conductivity measurements, t.g./d.t.g. methods, magnetic susceptibilities and spectroscopic (i.r., far-i.r., ligand field,¹Hn.m.r.) studies. Monomeric pseudo-octahedral stereochemistries for the Co^II, Ni^II and Cu^II complexes andcis square planar structures for the compounds [ML_BX₂] (M=Pd or Pt; X=Cl or Br) are assigned in the solid state. The molecules L_A and L_B behave as tetradentate chelate ligands in the Co^II, Ni^II, Cu^II and Magnus-type Pd^II and Pt^II complexes, bonding through both the pyridine and methine nitrogen atoms. A bidentateN-methine coordination of the Schiff base L_B is assigned in the [ML_BX₂] complexes (M=Pd or Pt; X=Cl or Br). The anomalous magnetic moment values of the Co^II complexes are discussed.     

Cobalt(II), Nickel(II), and Copper(II) Complexes with Diphenylthiocarbazide

New [ML(H₂O)₂] complexes (M = Co²⁺, Ni²⁺, or Cu²⁺; H₂L = diphenylthiocarbazide) were synthesized and studied using IR and diffuse reflection electronic spectroscopy, magnetic chemistry, conductometry, and DTA. The metals were shown to coordinate L^2–through nitrogen and sulfur atoms. The complex [CuL(H₂O)₂] is a dimer.     

N-Phthaloylglycinate ternary complexes with cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) metal ions and aromatic mono,bi and tridentate amines

Complexes of N-phthaloylglycinate (N-phthgly) and Co^II, Ni^II, Cu^II, Zn^II and Cd^II containing imidazole (imi), N-methylimidazole (mimi), 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen), and tridentate amines such as 2,2,2-terpyridine (terpy) and 2,4,6-(2-pyridyl)s-triazine (tptz), were prepared and characterized by conventional methods, i.r. spectra and by thermogravimetric analysis. For imi and mimi ternary complexes, the general formula [M(imi/mimi)₂(N-phthgly)₂]·nH₂O, where M = Co^II, Ni^II, Cu^II and Zn^II applies. For Cd^II ternary complexes with imi, [Cd(imi)₃(N-phthgly)₂]·2H₂O applies. For the bi and tridentate ligands, ternary complexes of the formula [M(L)(N-phthgly)₂]·nH₂O were obtained, where M = Co^II, Ni^II, Cu^II and Zn^II; L = bipy, phen, tptz and terpy. In all complexes, N-phthgly acts as a monodentate ligand, coordinating metal ions through the carboxylate oxygen, except for the ternary complexes of Co^II, Ni^II and Cu^II with mimi and Cu^II and Zn^II with imi, where the N-phthgly acts as a bidentate ligand, coordinating the metal ions through both carboxylate oxygen atoms.     

Studies on 4-(2-thiazolyl)-1-(2-acetylpyridine)thiosemicarbazone complexes of some bivalent metal ions

Summary Complexes [VO(Htaptsc)SO₄] and [M(Htaptsc)₂Cl₂] [M=Mn^II, Ni^II, Cd^II or Hg^II], Cu(Htaptsc)Cl₂ and [M(Htaptsc)Cl₂] [M=Co^II or Zn^II], and deprotonated compounds Co(taptsc)₂ and [M(taptsc)₂] [M=V^IVO, Mn^II, Ni^II, Cu^II or Zn^II] [Htaptsc=4-(2-thiazolyl)-1-(2-acetylpyridine)thiosemicarbazone] have been characterized by elemental analyses, electrical conductivity and magnetic susceptibility measurements and electronic, e.s.r. and i.r. spectroscopy. The bonding sites of Htaptsc and the bonding and stereochemistry of the complexes are discussed.     

Cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin

A new series of hexacoordinate cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin HL having formulae [LM(OAc)(H₂O)₂] · nH₂O (M = Co^II, Cu^II and Ni^II), [LMCl(H₂O)₂] · nH₂O (M = Co^II and Ni^II), [LCuCl(H₂O)]₂ · 2H₂O, [LCu(H₂O)₃](ClO₄) and [LCu(HSO₄)(H₂O)₂] were isolated and characterized by elemental analyses, molar conductivities and magnetic susceptibilities, and by i.r., electronic and e.s.r. spectral measurements, as well as by thermal (t.g. and d.t.g.) analyses. The i.r. spectra indicate that the ligand HL behaves as a monobasic tridentate towards the three divalent metal ions via an azo-N, carboxylate-O and thiohydantoin-O atom. The magnetic moments and electronic spectral data suggest an octahedral geometry for Co^II complexes, distorted octahedral geometry for both Ni^II and Cu^II complexes with a dimeric structure for [LCuCl(H₂O)]₂ · 2H₂O through bridged chloro ligands. The X-band e.s.r. spectra reveal an axial symmetry for the copper(II) complexes with unsymmetrical M_s = ± 1 signal and G-parameter less than four for the dimeric [LCuCl(H₂O)]₂ · 2H₂O. The thermogravimetry (t.g. and d.t.g.) of some complexes were studied; the order and kinetic parameters of their thermal degradation were determined by applying Coats–Redfern method and discussed.     

Synthesis and characterization of new metal complexes of thiosemicarbazone derived from 4-phenyl-3-thiosemicarbazide and chromone-3-carboxaldehyde

Summary The reaction between chromone-3-carboxaldehyde-4-phenylthiosemicarbazone (HCPT) and some hydrated metal salts of Co^II, Ni^II and Cu^II give complexes of the type [Cu(HCPT)Cl₂],[Cu(CPT)BrH₂O],[Cu(CPT)₂]·2H₂O, [Ni(CPT)₂(H₂O)₂]·2H₂O, [Co(CPT)₂(OAc)] and [Co(CPT)₂(H₂O)₂]X·2H₂O (where X=Cl or Br). The metal complexes were characterized by elemental analyses, molar conductivities, and spectal (i.r. and visible) and magnetic studies. I.r. spectra show that the HCPT coordinates in the thione or thiol form and behaves in a bidentate manner. Also, HCPT behaves as an oxidizing agent towards Co^II forming diamagnetic Co^III complexes. An octahedral structure is proposed for both Co^III and Ni^II complexes, while a square-planar structure is proposed for Cu^II complexes on the basis of magnetic and spectral measurements.     

N-acetyl-DL-leucinate cobalt(II), nickel(II) and zinc(II) complexes

Summary Complexes of the type M(AcLeu)₂ · B₂ (M = Co^II, Ni^II or Zn^II; B = H₂O, py, 3-pic, 4-pic; AcLeu =N-acetyl-DL-leucinate ion) and M(AcLeu)₂ B (M = Co^II or Zn^II and B = o-phen) were prepared and investigated by means of magnetic and spectroscopic measurements. The i.r. spectra of all the complexes are consistent with bidentate coordination of the amino acid to the metal ion. The room temperature solid state electronic spectra indicate that the symmetry of this species is closer toD _4h and that MO₆ and MO₄N₂ chromophores are present in the M(AcLeu)₂ · 2 H₂O and M(AcLeu)₂B_n · x H₂O (B = py, 3-pic, 4-pic, n=2 and x=0 for M = Ni^II; B = o-phen, n=1 and x=0 for M = Co^II; B = py, 3-pic, 4-pic, n=1 and x=1 for M = Co^II) complexes, respectively. By comparing the Dq values of the amino acid and those of other N-substituted amino acids previously studied, a spectrochemical series of the the cobalt(II) and nickel(II) complexes is proposed. The¹ H n.m.r. spectra of the zinc(II) complexes confirm the proposed stereochemistry.     

Studies on 4-(2-thiazolyl)-1-(2,6-diacetylpyridine)thiosemicarbazone complexes of some bivalent metal ions

Summary Complexes of 4-(2-thiazolyl)-1-(2,6-diacetylpyridine)-thiosemicarbazone, H₂C₃NSCNH(S)NHNCMeC₅H₃N-C(O)Me (Htdaptsc) of the compositions [M(Htdaptsc)₂Cl₂] [M=Mn^II, Co^II, Ni^II or Zn^II] [M(Htdaptsc)Cl₂] [M=Zn^II, Cd^II or Hg^II] and [M(tdaptsc)₂] [M=Mn^II, Co^II, Ni^II, Cu^II, or Zn^II] have been prepared and characterized by elemental analyses, molar conductance, magnetic susceptibility, electronic, e.s.r. and i.r. studies, and their stereochemistries are discussed.     

Studies ono-hydroxyacetophenone-2-furoylhydrazone complexes of some 3d-bivalent metal ions

Summary Complexes ofo-hydroxyacetophenone-2-furoylhydrazone, H₂L, of the types M(H₂L)C1₂ · nH₂O [Mn = Co^II, n=0; Ni^II, n=2]; Cu(HL)Cl, M(HL)₂ [M = V^IVO, Co^II, Ni^II or Cu^II] and M(L)(H₂O)_n [M = Co^II or Ni^II, n=2; M = Cu^II, n=0] have been prepared and characterized by elemental analyses, molar conductance, magnetic susceptibility, visible, e.s.r. and i.r. spectral studies. The different modes of ligand chelation and the stereochemistry around the metal ions are discussed.     

Nitrates and bis(dithiooxalato)nickelates(II) of biacetyldihydrazone complexes

Summary Biacetyldihydrazone (BdH) complexes [M(BdH)₃](NO₃)₂ (M=Co^II, Ni^II, Cu^II or Zn^II); [Fe(BdH)₃](NO₃)₃; [M(BdH)₃][Ni(dto)₂] (M=Co^II, Ni^II or Zn^II; dto=dithiooxalate); [Cu(BdH)₂][Ni(dto)₂] and [Fe(BdH)₃]₂[Ni(dto)₂]₃ have been prepared and characterized by chemical analysis, conductance measurements, electronic and i.r. spectral studies and cyclic voltammetry.A mononuclear octahedral configuration is proposed for all cationic complexes, excepting [Cu(BdH)₂][Ni(dto)₂, which is probably a dithiooxalate bridged dimer.     

Metal complexes of 2-acetylpyridine N(4)-dihexyl- and N(4)-dicyclohexylthiosemicarbazones

Summary 2-Acetylpyridine N(4)-dihexyl- and N(4)-dicyclohexylthiosemicarbazone, HAc4DHex and HAc4DCHex, respectively, and Fe^III, Co^II, Co^III, Ni^II, Cu^II and Zn^II complexes have been prepared and characterized by molar conductivities, magnetic susceptibilities and spectroscopic techniques. For many of the complexes, loss of the N(2)H hydrogen occurs, and the ligands coordinate to the metal centres as NNS monoanionic, tridentate ligands, e.g., [M(NNS)X] (M = Co^II, Ni^II, Cu^II, NNS = Ac4DHex or Ac4DCHex and X = Cl or Br), [Fe(NNS)₂]ClO₄, [Co(NNS)₂]BF₄, [Cu(NNS)NO₃] and [Zn(NNS)OAc]. Zn^II ion is also chelated by neutral ligands in [Zn(HNNS)X₂] (X = Cl, Br). In addition, [Ni(Ac4DHex)-(HAc4DHex)]X (X = BF₄, ClO₄) and [Ni(HAc4DCHex)₂]-(BF₄)₂ are reported where the neutral thiosemicarbazone is coordinated via the pyridyl nitrogen, azomethine nitrogen and thione sulfur. Crystal structure determinations of HAc4DCHex and [Cu(Ac4DHex)Br] show the former to contain the bifurcated hydrogen bonded form and the latter to be planar with no significant interaction between neighbouring centres.     

Synthesis and spectral studies of copper(II), nickel(II), cobalt(II) and vanadyl(II) complexes of tridentate Schiff bases of 1,2,3,5,6,7,8,8a-octahydro-3-oxo-N,1-diphenyl-5-(phenylmethylene)-2-naphthalenecarboxamide

Summary Metal(II) chelates of Schiff bases derived from the condensation of 1,2,3,5,6,7,8,8a-octahydro-3-oxo-N,1-diphenyl-5-(phenylmethylene)-2-naphthalenecarboxamide with o-aminophenol (KAAP), o-aminothiophenol (KAAT) or o-aminobenzoic acid (KAAB) have been prepared and characterized. The complexes are of the type [M(N₂X)]₂ for M = Cu^II and M(NX)₂·nH₂O for M = Ni^II, Co^II and VO^II (X = phenolic oxygen, thiophenolic sulphur or carboxylic oxygen; n = 0 or 2). Conductivity data indicate that the complexes are non-ionic. The Schiff bases behave as dibasic tridentate ligands in their copper(II) complexes and as monobasic bidentate ligands in their nickel(II), cobalt(II) and vanadyl(II) complexes. The subnormal magnetic moments of the copper(II) complexes are ascribed to an antiferromagnetic exchange interaction arising from dimerization. Nickel(II) and cobalt(II) complexes are trans octahedral whereas vanadyl(II) complexes are square pyramidal     

Dicyanamide complexes of copper(II), nickel(II) and cobalt(II) with benzimidazole and its 2-alkyl-derivatives

Summary Dicyanamide complexes of Cu^II, Ni^II and Co^II of the type M[N(CN)₂]₂L₂, where L = benzimidazole, 2-methyl- or 2-ethylbenzimidazole, have been prepared and studied by spectroscopy and magnetochemistry. The complexes, except for Co[N(CN)₂]₂ (benzimidazole)₂, are six-coordinate, involving bidentate bridging dicyanamide groups. While the Ni^II complexes have practically octahedral structures, the Cu^II complexes are pseudooctahedral with similar tetragonal distortion. The ligand field strength in these complexes depends mainly on the steric effect of the benzimidazole ligands. The Co^II complex of benzimidazole is monomeric tetrahedral, but that of 2-ethylbenzimidazole is tetragonal octahedral. The oridging function of dicyanamide in the six-coordinate complexes is realized either through both cyanide or through amide and cyanide nitrogens. The complex Cu[N(CN)₂]₂ (2-methylbenzimidazole)₂ is a weak antiferromagnet (J = -0.1 cm^–1), exhibiting under ca. 15 K a long-range antiferromagnetic ordering.     

New complexes of iron(III), cobalt(II), nickel(II) and copper(II) with 2-phenyl-1,2,3-triazole-4-carboxalidene-2-aminophenol

Summary Fe^III, Co^II, Ni^II and Cu^II complexes of a new Schiff base, 2-phenyl-1,2,3-triazole-4-carboxalidene-2-aminophenol (PTCAP), have been synthesized and characterized by elemental analyses, molar conductance and magnetic susceptibility measurements, and by u.v.-vis., i.r. and e.p.r. spectral observations. The studies indicate an octahedral structure for the complexes with the general formula [ML₂] (M = Co^II, Ni^II or Cu^II.; L = PTCAP) or [M′(OH)L₂] (M′ = Fe^III). The i.r. spectra suggest that the ligand acts as a tridentate (NNO) donor towards Co^II, Ni^II and Cu^II, and, in the Fe^III complex, one of the two ligand molecules acts as a bidentate (NO) donor and the other as a tridentate donor. The M?ssbauer spectrum of the Fe^III complex suggests the presence of a spin equilibrium at room temperature. Cyclic voltammograms are also recorded for the Cu^II and Fe^III complexes.