A new binucleating ligand incorporating four oxime groups and its copper(II), manganese(II) and cobalt(III) complexes

A new binucleating ligand incorporating four oxime groups, butane-2,3-dione O-[4-aminooxy-2,3-bis-(2-hydroxyimino-1-methyl-propylideneaminooxymethyl)-but-2-enyl]-dioxime, (H₄mto), has been synthesized and its dinuclear cobalt(III), copper(II), and homo- and hetero-tetranuclear copper(II)–manganese(II) complexes have been prepared and characterized by ¹H- and ¹³C-n.m.r., i.r., magnetic moments and mass spectral studies. Elemental analyses, stoichiometric and spectroscopic data indicate that the metal ions in the complexes are coordinated to the oxime nitrogen atoms (C=N) and the data support the proposed structure for H₄mto and its complexes. Moreover, dinuclear cobalt(III) and copper(II) complexes of H₄mto have a 2:1 metal:ligand ratio.     

Synthesis and physico-chemical studies on cobalt(II), nickel(II) and copper(II) complexes of benzidine diacetyloxime

The synthesis of benzidine diacetyloxime (H₂L) and its cobalt(II), nickel(II) and copper(II) complexes is described. The complexes were characterized by elemental analyses, molar conductivities, magnetic moments, i.r., u.v.–vis. spectra, t.g.a. and e.s.r. measurements. I.r. spectra show that H₂L behaves as a neutral or dinegative ligand depending on the nature of the metal salts. The molar conductances of the complexes in DMF are commensurate with their non-ionic character. The e.s.r. spectrum of the solid copper(II) complex (7) at room temperature shows broad signal, indicating spin-exchange interactions between copper(II) ions. However, in TMHF solution at 77 K, it shows an axial type ground state with mixed ionic-covalent bond character.     

Direct synthesis,spectral and magnetic properties of trans-aniono(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7-acetato) copper(II) complexes

7-Carboxymethyl-7,16-diaza-18-crown-6 acid hydrates (LH·H₂O) and their copper(II) complexes [CuLX], (X = Cl, Br, NO₃, ClO₄ and CH₃CO₂) were obtained. The earlier X-ray investigation of the [CuLCl] complex, as well as the IR and UV-vis spectral evidence for the complexes revealed the inner chelate structure with the six-coordinated copper(II) ion embedded inside the macrocyclic ligand (deformed octahedral, 4+2, N,N, CO₂⁻,X⁻,O,O-coordination sphere) and the trans arrangement of the CO₂ and X ligands. The spectral data, the conductivity measurements and the chemical properties show the existence of the macrocyclic inclusion cation [CuL]⁺ and the formulation of the complexes as the [(CuL)⁺X⁻] inner salts. The magnetic moments of the complexes amount to 1.76–1.83 BM at room temperature and 1.3–0.92 BM at 4.2 K. These results revealed the monomeric form of the complexes with the occurrence of the intermolecular (through space) magnetic super-exchange interactions of copper(II) paramagnetic centres.     

Copper(II), nickel(II) and cobalt(II) complexes of oxaldihydrazide and succindihydrazide Schiff bases with salicylaldehyde ando-hydroxyacetophenone

Summary Polymeric copper(II), nickel(II) and cobalt(II) complexes of the type M₂L where M = Cu^II, Ni^II or Co^II and H₄L = disalicylaldimine oxamide (H₄A), di(o-hydroxyacetophenoneimine)oxamide (H₄B), disalicylaldimine succinamide (H₄C) or di(o-hydroxyacetophenoneimine)succinamide (H₄D), have been synthesized and characterized by analysis, i.r. and electronic spectra and magnetic moment data. Copper(II) complexes and some of the nickel(II) and cobalt(II) complexes are planar while other nickel(II) complexes are distorted octahedral and other cobalt(H) complexes are square pyramidal. Anomalously low magnetic moments of some complexes have been related to M-M interactionsvia oxo-bridge structures.     

Spectral and Structural Studies of the Copper(II) Complexes of 3, 4‐Hexanedione Bis(3‐azacyclothiosemicarbazones)

Copper(II) complexes of 3, 4‐hexanedione bis(piperidyl‐ and bis(hexamethyleneiminylthiosemicarbazone), H₂Hxpip and H₂Hxhexim, respectively, have been prepared and studied spectroscopically. The bis(thiosemicarbazones) have been characterized by their melting points, as well as IR, electronic and ¹H NMR spectra. Upon formation of their copper(II) complexes, loss of the hydrazinic hydrogen atoms occurs, and the ligands coordinate as dianionic, tetradentate N₂S₂ ligands. The crystal structures of H₂Hxpip, its 4‐coordinate copper(II) complex, [Cu(Hxpip)], and the related [Cu(Hxhexim)] have been determined by single crystal x‐ray diffraction. The nature of the four‐coordinate copper(II) complexes have also been characterized by ESR, IR, and electronic spectroscopy, as well as magnetic moments and elemental analyses.     

Synthesis and spectroscopic studies of transition metal dinuclear/ polynuclear complexes with azolo-2,4-pentanedione

Summary Biologically relevant azolo (triazolo and thiazolo) diazonium salts were coupled with 2,4-pentanedione. The resulting substituted 2,4-pentanedione (L₁ and L₂) were condensed with 1,6-diaminohexane in the presence of chloride salts of nickel(II), copper(II), platinum(II), platinum(IV) and palladium(II) or nickel(II) and copper(II) acetates. The resulting dinuclear/polynuclear complexes were characterized by elemental analyses, conductance and magnetic moments, as well as i.r., u.v.-vis., ¹H n.m.r. and e.s.r. spectra.     

Synthesis and magnetic properties of μ-phenolato copper (Ⅱ) binuclear complexes with different exogenous bridges

The syntheses and magnetic properties are reported for a series of copper(Ⅱ) complexes prepared from a pentadentate binucleating ligand 2,6-diformyl-4-methylphenol di(benzoyl-hydrazone) (H3L). These complexes incorporate different exogenous ions (X-) into a bridging position to form copper(Ⅱ) binuclear complexes of the formula [Cu2(H2L)X]2+, where X-= Br-(1), Cl-(2), HO-(3), C2H5O-(4) and C3H3N2- (5). The complexes have been characterized with variable temperature magnetic susceptibility (4.2-300 K) and the observed data were fit to those from a modified Bleaney-Bowers equation by least-squares method, giving the exchange integral 2J = -6.2 cm-1 for 1, -76.4 cm-1 for 2, -241.9 cm-1 for 3, -231.1 cm-1 for 4 and -343.8 cm-1 for 5. This suggested that there is an antiferromagnetic interaction between the Cu(Ⅱ) ions and the sequence of the effect of some exogenous bridging ligands on magnetic coupling is corresponding to that in spectrochemical series.     

Synthesis,spectral, electrochemical and magnetic properties of new asymmetric dicopper(II) complexes bearing chemically distinct coordination sites

Two new unsymmetrical binucleating ligands, 2-[bis(3-N, N-dimethylaminopropyl)-aminomethyl]-6-[prolin-1-yl)methyl]-4-bromophenol [H ₂L¹] and 2-[bis(3-N, N -dimethylaminopropyl)aminomethyl]-6-[prolin-1-yl)methyl]-4-methylphenol [H₂L²], and their dicopper(II) complexes with different exogenous bridging motifs (OAc, Br and Cl) have been prepared and characterized by spectral, electrochemical, magnetic and e.p.r. studies. Electrochemical studies indicate the presence of two irreversible reduction peaks in the cathodic region. Variable temperature magnetic susceptibility studies of the complexes show that the extent of antiferromagnetic coupling increases in the order: OAc^–< Cl^–< Br^–. Broad isotropic or axial symmetric spectral features are observed in powder e.p.r. spectra of the complexes at 77K. A comparison of the electrochemical and magnetic behaviour of the complexes derived from the ligands is discussed on the basis of an exogenous bridge as well as the substituent at the para position of the phenolic ring.     

Mononuclear and binuclear manganese(II) complexes with tridentate bis-benzimidazolyl ligands

Summary Manganese(II) complexes of bis(2-benzimidazolylmethyl) ether (DGB), bis(2-benzimidazolylmethyl) sulphide (TGB) and the n-butyl derivative of DGB (BDGB) were prepared and characterised. The solution e.p.r. spectrum of [Mn(TGB)Cl₂] in DMF at 143 K is commensurate with an axially distorted monomeric manganese(II) complex, room temperature magnetic moment (6.04 B.M.) per manganese(II) atom being in the range found for other d⁵ monomeric manganese(II) complexes. The solution e.p.r. spectrum of [Mn(BDGB)Cl₂]-2H₂O in DMF at 143 K indicates the presence of two equivalent manganese(II) ions coupled by an exchange interaction, fostered by bridging chlorides. Evidence for this is provided by a nearly isotropic 11 line hyperfine structure of ⁵⁵Mn, with a coupling constant 45 ± 5G. Contact-shifted ¹H n.m.r. data also supports an exchange coupled dimeric manganese complex. The room temperature magnetic moment, 5.64 B.M., per manganese(II) indicates quenching of the magnetic moment below that of monomeric manganese(II) ion. The [Mn(DGB)Cl₂]·H₂O complex exhibits a magnetic moment of 6.02 B.M. per manganese, indicating a monomeric manganese complex. E.p.r. data of the complex diluted in an analogous Zn-DGB complex (1∶20) correlates well for D = 0.22cm⁻¹ and λ ∼- 0.267. The [Mn(DGB)-(C1O₄)₂] and [Mn(BDGB)(ClO₄)₂] complexes, diluted in analogous Zn-DGB and Zn-BDGB complexes (1∶20), show a strong single e.p.r. line at g _eff ∼- 2. The complexes have low magnetic moments; 4.44 B.M./Mn and 4.39 B.M./Mn, at room temperature.     

Mono-, di- and trinuclear copper(II) dioxime complexes; 3-{2-[2-(2-hydroxyimino-1-methylpropylideneamino)ethylamino]ethylimino}butan-2-one oxime

A new ligand incorporating a dioxime moiety, 3-{2-[2-(2-hydroxyimino-1-methylpropylideneamino)ethylamino]ethylimino}butan-2-one oxime, (H₂mdo), has been synthesized and its mono-, di- and trinuclear copper(II), and hetero-dinuclear copper(II)–manganese(II) complexes have been prepared and characterized by elemental analyses, magnetic moments, ¹H- and ¹³C-n.m.r., i.r. and mass spectral studies. A mononuclear copper(II) complex of H₂mdo was found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N); the data support the proposed structure of H₂mdo and its complexes.     

Cobalt(II), nickel(II) and copper(II) complexes of 4-(sulfonylazido)phenylazopyrazolones

Transition metal complexes of Co^II, Ni^II and Cu^II with 4-(4-azidosulfophenylazo)-5-phenyl-3,4-dihydro-2H-pyrazol-3-oneHL¹, 4-(4-azidosulfophenylazo)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-one HL² and 4-(3-azidosulfo-6-methoxyphenylazo)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-one HL³ were prepared and characterized by elemental analyses, molar conductances and magnetic susceptibilities and by i.r., electronic and e.s.r. spectral measurements as well as thermal (d.t.a and t.g.a.) analysis. The i.r. spectra indicate that HL acts as a bidentate ligand coordinating via the azo and enolic-oxygen linkages. The electronic spectral data and magnetic moments suggest a tetragonally distorted octahedral geometry for the complexes having the formula ML₂·2H₂O, (M = Co^II, Ni^II and Cu^II), square pyramidal geometry for CuL ₂ ³ H₂O and tetrahedral geometry for CoL ₂ ³ . The X-band e.s.r. spectra of the copper(II) complexes reveal anaxial symmetry for both CuL ₂ ² 2H₂O and CuL ₂ ³ H₂O while CuL ₂ ¹ O is isotropic in the solid state at room temperature. The d.t.a. curves show two exothermic peaks for all three complexes CoL ₂ ³ ,NiL ₂ ³ 2H₂O and CuL ₂ ³ H₂O and one endothermic peak for the latter two aqua complexes.     

Synthesis and complexation of two new phenylaminoglyoxime ligands

Two new soluble phenylaminoglyoxime ligands, 4-isopropylanilinephenylglyoxime (L¹H₂), 4-benzylpiperidinephenylglyoxime (L²H₂), were prepared by reacting 4-isopropylaniline and 4-benzylpiperidine with chlorophenylglyoxime. Mononuclear nickel(II), cobalt(II), copper(II), zinc(II), and cadmium(II) complexes with these ligands were synthesized. On the basis of the magnetic and spectral evidence a square-planar geometry for Ni(II) and Cu(II) complexes, a tedrahedral geometry for Cd(II) and Zn(II) complexes and octahedral geometry for Co(II) complexes are proposed. These compounds were elucidated by elemental analysis, IR, UV-Vis, and magnetic moments. The ligands were additionally characterized by ¹H NMR and ¹³C NMR spectra.     

Synthesis and characterisation of nickel(II), cobalt(II), manganese(II), copper(II), zinc(II), dioxouranium(VI) and dioxomolybdenum(VI) complexes of tridentate dibasic ONO donor Schiff bases derived from 2-benzothiazolecarbohydrazide and salicylaldehyde/2-hydroxy-1-naphthaldehyde

Summary The syntheses of several new coordination complexes of nickel(II), cobalt(II), manganese(II), copper(II), zinc(II), dioxouranium(VI) and dioxomolybdenum(VI) with new Schiff bases derived from 2-benzothiazolecarbohydrazide and salicylaldehyde or 2-hydroxy-1-naphthaldehyde are described. These complexes have been characterised by elemental analyses, electrical conductance, magnetic susceptibility, molecular weight, i.r. and electronic spectra. The Schiff bases behave as dibasic and tridentate ligands coordinating through the ONO donor system and form complexes of the types NiL · 3H₂O, MnL · 2H₂O, CoL · 2H₂O, CuL, ZnL · H₂O, UO₂L · MeOH and MoO₂L · MeOH (where LH₂ = Schiff base). The copper(II) complexes exhibit subnormal magnetic moments indicating the presence of an antiferromagnetic exchange interaction, whereas the nickel(II), cobalt(II) and manganese(II) complexes behave normally at room temperature. Zinc(II), dioxouranium(VI) and dioxomolybdenum(VI) complexes are diamagnetic; the zinc (II) complexes are tetrahedral, the copper(II) complexes are square planar, all the other complexes are octahedral. Thev(C=N),v(C-O),v(N-N) andv(C-S) shifts have been measured in order to locate the Schiff base coordination sites.     

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 structural studies of (2 E ,3 E ,6 R ,9 E ,11 E )-6-isopropenyl-3,6,10-trimethyl-5,8-dioxa-4,9-diazadodeca-3,9-diene-2,11-dione dioxime, ligand and its Mono-, homo, and heterodinuclear copper(II)/nickel(II) complexes

This article describes the synthesis of a new (2E,3E,6R,9E,11E)-6-isopropenyl-3,6,10-trimethyl-5,8-dioxa-4,9-diazadodeca-3,9-diene-2,11-dione dioxime (H₂hmdm), and its mono-, homo, and heterodinuclear copper(II)/nickel(II) complexes. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). The Cu(H₂hmdm), molecule coordinates to the second copper(II) ion through the oximate oxygens to afford a binuclear structure doubly bridged by the oximate groups in the cis arrangement. In the dinuclear complexes, in which the first Cu^II ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu^II ion is ligated with the 1,10-phenanthroline nitrogen atoms. Ligand and its mononuclear copper(II), homo and heterodinuclear copper(II)–nickel(II) complexes of (H₂hmdm) were characterized by elemental analyses, magnetic moments, ¹H-n.m.r. and ¹³C-n.m.r., i.r., and mass spectral studies. The data support the proposed structure of H₂hmdm and its complexes.     

Mixed-ligand fluorocuprates(II). Synthesis and characterisation of [CuF3L(H2O)2]− containing amino acids as coligands

Complex species of the type NH₄[CuF₃L(H₂O)₂] · nH₂O (L = glycine, n = 1; 1-alanine, n = 0) have been prepared by reacting hydrated copper(II) oxide, CuO · nH₂O, with the amino acids in the presence of bifluoride, HF₂ ^–, in aqueous solution. The order of addition of the ligands, fluoride and amino acids is crucial to the synthesis. A reaction solution pH lower than the isoelectric point of the respective amino acids seems to favour the formation of mixed-ligand fluoro complexes. Occurring as zwitterions, the amino acids in the complexes have been shown to be bonded to the copper(II) centre via the carboxyl (—COO^–) moiety representing an unexpected non-chelated form of the coligands. Magnetic moments and e.s.r. data are consistent with six-coordinate copper(II) complexes.     

Synthesis and characterization of nickel(II), cobalt(II), copper(II), manganese(II), zinc(II), zirconium(IV), dioxouranium(VI) and dioxomolybdenum(VI) complexes of a new Schiff base derived from salicylaldehyde and 5-methylpyrazole-3-carbohydrazide

Summary Synthesis of a new Schiff base derived from salicylaldehyde and 5-methylpyrazole-3-carbohydrazide, and its coordination compounds with nickel(II), cobalt(II), copper(II), manganese(II), zinc(II), zirconium(IV), dioxouranium(VI) and dioxomolybdenum(VI) are described. The ligand and the complexes have been characterized on the basis of analytical, conductance, molecular weight, i.r., electronic and n.m.r. spectra and magnetic susceptibility measurements. The stoichiometries of the complexes are represented as NiL · 3H₂O, CoL · 2H₂O, CuL, MnL · 2H₂O, ZnL · H₂O, Zr(OH)₂(LH)₂, Zr(OH)₂L · 2MeOH, UO₂L · MeOH and MoO₂L · MeOH (where LH₂ = Schiff base). The copper(II) complex shows a subnormal magnetic moment due to antiferromagnetic exchange interaction while the nickel(II), cobalt(II) and manganese (II) complexes show normal magnetic moments at room temperature. The i.r. and n.m.r. spectral studies show that the Schiff base behaves as a dibasic and tridentate ligand coordinating through the deprotonated phenolic.oxygen, enolic oxygen and azomethine nitrogen.     

Binuclear Copper(II), Nickel(II) and Cobalt(II) Complexes with N2O2 Chromophores of Glycylglycine Schiff-Bases of Acetylacetone, Benzoylacetone and Thenoyltrifluoroacetone

Binuclear copper, nickel and cobalt complexes of the Schiff-bases obtained by condensation of glycylglycine with acetylacetone, benzoylacetone, dibenzoylmethane and thenoyltrifluoroacetone were prepared by template synthesis. The complexes were characterized by elemental analysis, conductivity measurements, magnetic moments, i.r., u.v.–vis. spectra, e.s.r., X-ray diffraction, t.g.a., d.t.a. and d.s.c. thermal analysis. All the complexes are non-electrolytes with low magnetic moments that indicate spin–spin or antiferromagnetic exchange interactions. Spectral properties support square planar and square pyramidal or trigonal bipyramidal structure provided by the N₂O₂ chromophores. E.s.r. spectra of the copper complex confirm the binuclear structure and the presence of magnetic interaction. Thermal studies supported the chemical formulation of these complexes and showed that they decompose in three to four steps depending on the type of ligand. Activation energies E_a and enthalpies ΔH, associated with the thermal decomposition of the complexes were calculated and correlated with the type of complexed metal. A mechanism for thermal decomposition is proposed for the complexes.     

Synthesis, Spectral Characterization and Electrochemical Properties of New vic-dioxime Complexes Bearing Carboxylate

Three new vic-dioxime ligands, [N-(ethyl-4-amino-1-piperidine carboxylate)-phenylglyoxime (L¹H₂), N-(ethyl-4-amino-1-piperidine carboxylate)-glyoxime (L²H₂), and N,N′-bis(ethyl-4-amino-1-piperidine carboxylate)-glyoxime (L³H₂)], and their Co(II) with Cu(II) metal complexes, were synthesized for the first time. Mononuclear complexes of these ligands with a 1:2 metal-ligand ratio were prepared with Co(II) and Cu(II) salts. The BF₂⁺-capped Co(II) and mononuclear complexes of the vic-dioxime were prepared for [Co(L¹·BF₂)₂] and [Co(L²·BF₂)₂]. The ligands act in a polydentate fashion bonding through nitrogen atoms in the presence of a base, as do most vic-dioximes. The cobalt(II) and copper(II) complexes are non-electrolytes as shown by their molar conductivities (Λ_M) in DMF. The structures of the ligands and complexes were determined by elemental analyses, FT-i.r., u.v.–vis., ¹H- and ¹³C-n.m.r. spectra, magnetic susceptibility measurements, and molar conductivity. The comparative electrochemical studies show that the stabilities of the reduced or oxidized species and the electrode potentials of the complexes are affected by the substituents attached on the oxime moieties of the complexes.     

Cobalt(II,III) and copper(II) complexes of 3-(2-furylidene) hydrazino-5,6-diphenyl-1,2,4-triazine

A new series of cobalt(II, III) and copper(II) complexes of 3-(2-furylidene) hydrazino-5,6-diphenyl-1,2,4-triazine (L) having formulae LM^IIX₂, L₂M^IIX₂ and LCo^IIIX₃, (X = Cl, OAc or ClO₄; M^II = Co^II or Cu^II) were isolated and characterized by elemental analyses, molar conductances, magnetic moments and i.r., electronic and e.s.r. spectral measurements. The i.r. spectra indicated that the ligand, L, behaves as a neutral bidentate towards divalent metal ions via a triazine-N, and azomethine-N, and acts as a tridentate towards cobalt(III) via the same two nitrogen atoms and the furan-O. The magnetic moments and electronic spectral data suggest a pseudo-tetrahedral geometry for [L₂Co]Cl₂, a diamagnetic tetragonally distorted octahedral geometry for [LCoCl₃], [LCo(OAc)₃] · 4H₂O and [LCo(H₂O)₃](ClO₄)₃ and a dimeric square pyramidal geometry for both [LCuCl₂] and [LCu(OAc)₂] · 2H₂O through bridged chloro and acetato ligands, respectively. The ligand field parameters (B, 10Dq and ) were evaluated from the electronic spectral data and magnetic moments and related to the bonding of the complexes. The X-band e.s.r. spectra showed three g values with large magnetic anisotropy for [L₂Co]Cl₂ in accordance with pseudo-tetrahedral Co^II complexes; axial pattern for [LCuCl₂], [LCu(OAc)₂] · 2H₂O and [L₂Cu(H₂O)₂](ClO₄)₂ with two g values and a signal due to M _s = ±2 transition for both chloro and acetato copper(II) complexes.