Complexes of 2-(2-hydroxyacetophenone)imino-5-(p-anisyl)-1,3,4-oxadiazole with some bivalent metals ions

Summary The metal complexes of the type [M(SB)₂(H₂O)₂] and [M(SB)₂][where M = Mn^II, Co^II, Ni^II or Cu^II, M = Zn^II Cd^II, Hg^II and Pb^II and SBH = 2-(2-hydroxyacetophenone)imino-5-(p-anisyl)-1,3,4-oxadiazole] have been prepared and characterised by elemental analyses, thermal analyses, magnetic measurements, electronic and infrared spectral studies. The complexes [M(SB)₂(H₂O)₂] possess octahedral structures, whereas complexes [M(SB)₂] are tetrahedral. The crystal field parameters of the Co^II and Ni^II complexes are also calculated.     

Structural studies of 3-amino-4-(substituted arylazo)-5-(1H)pyrazolone compounds

Summary Transition metal complexes of cobalt(II), nickel(II), copper(II) and palladium(II) with 3-amino-4-(arylazo)-5-(1H)pyrazolones (Aryl=Ph, 4-C₆H₄CO₂H, 4-C₆H₄-OMe, 3-C₆H₄Cl, 3-C₆H₄CO₂H, 3-C₆H₄NO₂, 3-C₆H₄-Me, 3-C₆H₄OH and 2-C₆H₄CO₂H) are discussed. The stoichiometry of the complexes is: 11, 23 Co^II; 11 Ni^II; 11, 21 Cu^II and 12 Pd^II. The investigations suggest rhombic symmetry with 4- or 5-coordinate Co^II, square planar and tetrahedral configuration for Ni^II, tetrahedral Cu^II and square planar for Pd^II complexes. The complexes contain no anions.     

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.     

2-Acetylfuran-2-furoylhydrazone complexes of some 3d-metal ions

Summary 2-Acetylfuran-2-furoylhydrazone (1), [HL] reacts with metal ions to yield the complexes of two types, compounds [VO(HL)SO₄] and M(HL)₂Cl₂ [M = Co^II, Ni^II or Cu^II] and compounds M(L)₂(H₂O)₂ [M = Co^II, Ni^II or Cu^II], depending on the pH of the medium. These complexes have been characterized by elemental analyses, molar conductance, magnetic susceptibility, visible, e.s.r. and i.r. spectral studies. Square pyramidal geometry for [VO(HL)SO₄] and octahedral geometry for the remaining complexes are proposed. Part of this work was presented at the Second EUCHEM Conference on Electronic Structures of Transition Metal Complexes, St. Patrick's College, Maynooth, Ireland, 1985.     

N-Ferrocenylcarbonyl-N′-benzoylhydrazine and its transition metal(II) complexes

Summary A new ferrocene derivative, N-ferrocenylcarbonyl-N-benzoylhydrazine (H₂FB) and its transition metal complexes, [M(FB)]₂·H₂O (M = Mn^II, Co^II, Cu^II, Zn^II, Cd^II or Hg^II) and M(HFB)₂·nH₂O (M = Mn^II or Cd^II) were prepared by reacting H₂FB with the metal(II) acetates and characterized by elemental analyses, i.r. and u.v. spectroscopy and t.g.a. H₂FB appears to act as a tetradentate ligand, coordinating to the metal through the nitrogen enolic oxygen atoms.     

Electrical conductivity,spectral and magnetic properties of some transition metal complexes derived from dimedone bis(4-phenylthiosemicarbazone)

Summary Co^II, Ni^II, Cu^II, Zn^II, Cd^II and U^VIO₂ complexes of 5, 5-dimethyl-1, 3-cyclohexanone bis(4-phenylthiosemicarbazone), H₂CPT, have been characterized by elemental analysis, i.r. and reflectance spectral studies, and magnetic moment measurements. I.r. spectra show that H₂CPT gives rise to dibasic quadridentate SNNS donor. A square-planar structure is proposed for the copper(II) complex and octahedral for cobalt(II) and nickel(II) complexes according to the magnetic and electronic spectral data. The electrical conductivities of H₂CPT and its CO^II, Ni^II, Cu^II and Cd^II complexes were measured. The positive temperature coefficient (d/dT) and the higher activation energies of H₂CPT and its Cd^II and Cu^II complexes is evidence of their semiconducting character.     

Synthesis and characterization of complexes of the first transition series cations with 2,2′-biimidazole and 2,2′-biimidazolate

Mononuclear [M(hfacac)₂(H₂biim)] complexes, where M = Mn^II, Fe^II, Co^II, Ni^II, Cu^II or Zn^II, hfacac = hexafluoroacetylacetonate, H₂biim = 2,2-biimidazole; dinuclear K₂[M₂(acac)₄(-biim)] (M = Cu^II or Zn^II) and tetranuclear K₂[M₄(acac)₈( ₄-biim)] (M = Co^II or Ni^II) complexes have been prepared and characterized by chemical analysis, conductance measurements, i.r., electronic and e.p.r. spectroscopies and by magnetic susceptibility measurements (in the 2–300 K range). Mn^II, Fe^II and Co^II are in a high spin state. The e.p.r. spectra of Cu^II and Mn^II compounds have been recorded.     

Preparation,characterization and antifungal properties of transition metal ion complexes of quadridentate N3S ligands

Summary New metal complexes [M(NNNS)X] (M = Ni^II, Cu^II, Zn^II and Cd^II; NNNS^– = anion of the quadridentate ligands formed from S-methyl--N-(2-aminophenyl)-methylenedithiocarbazate and pyridine-2-aldehyde or 6-methylpyridine-2-aldehyde; X = Cl, NCS, NO₃ or I) and [Co(NNNS)Cl₂]·2H₂O have been prepared and characterized by elemental analysis and conductance measurements. Magnetic and spectroscopic evidence support a five-coordinate structure for [M(NNNS)X] (M = Ni^II, Cu^II, Zn^II and Cd^II; X = Cl, NCS) and a squareplanar structure for [Ni(NNNS)]X (X = NO₃ or I). The [Co(NNNS)Cl₃]·2H₂O complex is low-spin and octahedral. The Schiff bases and some of their metal complexes were tested against three pathogenic fungi, Alternaria alternata, Curvularia geniculata and Fusarium palidoroseum. The metal complexes are less fungitoxic than the free ligands.     

Isostructural triazenido complexes of first row transition metals. Part 3. Low spin cyclopentadienyl complexes of cobalt(II) (η5-C5H5)(PPh3)(RN3R)Co

Summary Reaction of (PPh₃)₂Cl₂Co^II with TlC₅H₅ gave the new ( ⁵-C₅H₅)(PPh₃)ClCo^II complex. This complex reacted with Ag(RN₃R) or Cu(RN₃R) (R=p-MeC₆H₄,p-ClC₆H₄ or 3,5-Cl₂C₆H₃) to give the novel compounds ( ⁵-C₅H₅)(PPh₃)(RN₃R)Co^II, with a spin state of one half, which are representatives of the very small class of paramagnetic monocyclopentadienyl transition metal complexes. The structural conclusions are based on comparison with the isostructural [ ⁵-C₅H₅)(PPh₃)(RN₃R)Co^III]PF₆ complex, on the i.r. spectra and on the observed redox behaviour. The e.p.r. spectra are reported, but are not well enough resolved for the determination of the hyperfine interactions. The orbital scheme of the new complex is discussed in terms of a distorted octahedral crystal field in relation to the series of isostructural ( ⁵-C₅H₅)(PPh₃)(RN₃R)M^II (M = Fe, Co or Ni) complexes.     

Transition metal complexes derived from N-isonicotinamido-N′-benzoylthiocarbamide (H2IBTC)

Summary The synthesis and characterization of Cr^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and UO _inf2 ^sup2+ complexes of N-isonicotinamido-_N-benzoylthiocarbamide (H₂IBTC) are reported. I.r. spectral data show that the ligand behaves in a bidentate, tridentate and/or tetradentate manner. Different stereochemistries are proposed for Cr^III, Mn^II, Fe^III, Co^II, Ni^II and Cu^II complexes on the basis of spectral and magnetic studies. The i.r. data indicate that the carbonyl oxygen of the benzoyl moiety is the backbone of chelation in most complexes.     

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 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.     

Complexes of N-aroyl-N′-thiobenzohydrazide with cobalt(II), nickel(II) and zinc(II)

Summary New potential tetradentate ligands, N-benzoyl-N-thiobenzohydrazide (H₂BTBH) and N-salicyl-N-thiobenzohydrazide (H₂SBTH) have been prepared and characterized. Their complexes with Co^II, Ni^II and Zn^II have been prepared and characterized on the basis of elemental analyses, magnetic susceptibility measurements, and u.v.-vis., i.r. and ¹H-n.m.r. spectral studies. The bonding and stereochemistries of the complexes are discussed. H₂BTBH, H₂SBTH and the complexes have been screened towards a number of bacteria.     

Transition metal complexes with a polydentate Schiff base derived from 3-formylsalicylic acid and 1,2-bis(o-aminophenylthio)ethane

The reaction of 3-formylsalicylic acid with 1,2-bis(o-aminophenylthio)ethane yielded a Schiff base with eight donor centres N₂S₂O₄ of which the inner compartment is of an N₂S₂O₂ type and the outer is of the O₂O₂ type. The base forms several mononuclear homo- and hetero-dinuclear complexes: e.g. mononuclear Cu^II, Ni^II and dinuclear Cu^II, Ni^II, UO₂ ^VI complexes. Hetero-dinuclear complexes {[M]M}, where M = the inner metal ion Cu^II, Ni^II and M = the outer metal ion Pd^II, UO₂ ^VI are also reported. The complexes were characterised by elemental analyses, spectral, thermal and magnetic measurements. Dicopper and dinickel complexes exhibit subnormal magnetic moments showing spin pairing between two metal centres, via the phenolato oxygen, whereas other mono-copper and mono-nickel complexes (both mononuclear and hetero-dinuclear) show the expected magnetic behaviour for 1e and 2e, respectively. The e.s.r. spectra of copper complexes also support the above behaviour.     

Trinuclear,Oxo-Bridged,Mixed-Valence Iron Mercaptocarboxylates

Mixed carboxylates and mercaptocarboxylates of mixed-valence Fe^IIFe^III with general formula [Fe^II-Fe^III ₂O(OOCR)₃(OOCRSH)₃L₃](where R = C₁₃H₂₇, C₁₅H₃₁ or C₁₇H₃₅; R= CH₂ or C₆H₄ and L = pyridine) were successfully prepared by substitution of [Fe^IIFe^III ₂O(OAc)₆(H₂O)₃] with straight chain carboxylic acids and mercaptocarboxylic acids. The title products have been characterized by elemental analyses, molar conductances and magnetic susceptibility measurements, i.r., electronic and Mössbauer spectral data. The i.r. spectra showed resolved bands arising from the _asym(OCO) and _sym(OCO) vibrations of the bridging carboxylate and mercaptocarboxylate ligands along with the _asym(Fe₃O) vibrations. Mössbauer spectroscopic studies revealed two resolved quadrupole doublets due to Fe^II and Fe^III at 80, 200 and 295 K, confirming the valence-localized type of compound. This fact has also been supported by the observed electronic spectral bands in the complexes. Magnetic susceptibility measurements showed net anti-ferromagnetic coupling related to mixed-valence pairs. A structure for the complexes has been established on the basis of physico-chemical studies.     

Synthesis and characterization of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with acetylacetone bis-benzoylhydrazone and acetylacetone bis-isonicotinoylhydrazone

Summary Acetylacetone bis-benzoylhydrazone (PhCONHN=CMe)₂ CH₂(LH₂) and acetylacetone bis-isonicotinoylhydrazone (NC₅H₄CONHN=CMe)₂CH₂(LH₂) complexes of the types [ML] and [ML] (M = Co^II, Ni^II, Cu^II or Zn^II) have been prepared and characterized. All the complexes are non-electrolytes and the cobalt(II) complexes are lowspin, the nickel(II) complexes are diamagnetic and the copper(II) complexes are paramagnetic. The ligands chelate via two C=N groups and two deprotonated enolate groups. The e.s.r. spectra of the copper(II) complexes indicate a tetragonally distorted dimeric structure. The X-ray diffraction parameters for [CoL] and [NiL] correspond to a tetragonal crystal lattice.     

Synthesis and spectral studies of copper(II), nickel(II) and cobalt(II) complexes of 2-hydroxy-ω-4-X-cinnamoyl acetophenones and their pyridine adducts

Summary Complexes of the type M(HXCA)₂·nH₂O (M = Cu^II, Ni^II or Co^II; HXCA = 2-hydroxy--4-X-cinnamoyl acetophenone; X = H, Cl, Me or OMe; n = 0 or 2) have been synthesized, and characterized by elemental analysis, i.r., electronic, ¹H-n.m.r. and e.s.r. spectroscopies, and magnetic susceptibility measurements. The spectral data indicate that the ligand coordinates through both carbonyl and enolic oxygens. The anhydrous Cu^II complexes are monomeric and square planar, while the Ni^II and Co^II analogues possess polymeric high-spin octahedral structures. The diaquates and dipyridinates of Co^II and Ni^II have monomeric high-spin octahedral geometries.     

Synthesis,spectral and thermal studies of monomeric,homobimetallic and polymeric complexes containing benzoyldithiocarbazate

New mixed ligand complexes of benzoyldithiocarbazate (H₂BDT) have been synthesized and characterized by elemental analyses, spectral studies (i.r., u.v.–vis., mass), thermal analysis and electrical conductivity measurements. The complexes have the general formulae: [M₂(BDT)(OX)₂] · xH₂O; [Co₂(BDT)(OX)₂(H₂O)₄]; [M(HBDT)(OX)-(H₂O)], [Ni(BDT)(py)₂] _n and [Ni(BDT)(L)] _n where M = Mn^II, Ni^II and Cu^II; BDT = dithiocarbazate dianion; OX = 8-hydroxyquinolinate; x = 1 or 2; M = Zn^II or Cd^II; HBDT = dithiocarbazate anion and L = 2,2-bipyridyl or 1,10-o-phenanthroline. For the [M₂(BDT)(OX)₂] · xH₂O, [Co₂(BDT)(OX)₂(H₂O)₄], [Ni(BDT)(py)₂] _n and [Ni(BDT)(L)] _n complexes, benzoyldithiocarbazate acts as a dibasic-tetradentate ligand in the enol form via the enolic oxygen, the hydrazide nitrogens and the thiolate sulphur, while it acts as a monobasic-tridentate ligand in the keto form in the [M(HBDT)(OX)(H₂O)] complexes. The thermal behaviour of the complexes has been studied by t.g.–d.t.g. techniques. Kinetic parameters of the thermal decomposition process have been computed by Coats–Redfern and Horowitz–Metzger methods. It is obvious that the thermal decomposition in the complexes occurs directly at the metal–ligand bonds except for the Zn^II and Cd^II complexes in which decomposition seems to be at a point in the benzoyldithiocarbazate moiety. From the calculated kinetic data it can be concluded that the dehydration processes in all complexes have been described as phase-boundary controlled reactions. The activation energy values reveal that the thermal stabilities of the homobimetallic complexes lie in the order: Mn^II < Ni^II < Co^II, while the monomeric Cd^II complex has more enhanced thermal stability than the Zn^II complex.     

Complexes of N-nicotinoyl-N′-2-furanthiocarbohydrazide with oxovanadium(IV), manganese(II), iron(II & III), cobalt(II), nickel(II), copper(II) and zinc(II)

A new potential tetradentate ligand, N-nicotinoyl-N-2-furanthiocarbohydrazide (H₂Nfth), and its complexes with VO^IV, Mn^II, Fe^II,III, Co^II, Ni^II, Cu^II and Zn^II have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, u.v.–vis, i.r., n.m.r., ES⁺ and FAB mass spectral data. The room temperature e.s.r spectra of the VO^IV and Fe^III complexes yield g values, characteristic of octahedral complexes. The Mössbauer spectra of [Fe(HNfth)₂] and [Fe₂(Nfth)₃] at room temperature and at 78 K suggest the presence of high-spin iron(II) and iron(III), respectively. The complexes are electrically insulating at room temperature, however, their conductivities increase as the temperature increases from 333–383 K, with a band gap of 0.46–0.77 eV, indicating their semiconducting behaviour. H₂Nfth and its soluble complexes have been screened against several bacteria and fungi.     

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.