Binuclear nickel(II) complexes with a bridging carbonato ligand

Three nickel(II) dinuclear carbonato-bridged complexes: (-CO3)[Ni(TAA)]2(ClO4)2·4H2O (1), (-CO3)[Ni(TTA)]2- (ClO4)2·2H2O (2), (-CO3)[Ni(cyclam)]2(ClO4)2 (3) [TAA =N(CH2CH2NH2)3,TTA=triethylenetetramine,cyclam = 1,4,8,11-tetraazacyclotetradecane] have been prepared. The temperature dependence of the magnetic susceptibility for (1), (2) and (3) were measured over the 77–300K range and the observed data were successfully simulated by an equation based on the spin Hamiltonian operator (H= –2JS1S2), giving the exchange integral J=–7.75cm–1 for (1), J=–1.23 cm–1 for (2) and J=–40.26cm–1 for (3).     

Chromium(III), manganese(II), iron(III), cobalt(II), nickel(II) and copper(II) complexes with a pentadentate, 15-membered new macrocyclic ligand

Complexes of Cr^III, Mn^II, Fe^III, Co^II, Ni^II and Cu^II containing a macrocyclic pentadentate nitrogen–sulphur donor ligand have been prepared via reaction of a pentadentate ligand (N₃S₂) with transition metal ions. The N₃S₂ ligand was prepared by [1 + 1] condensation of 2,6-diacetylpyridine with 1,2-di(o-aminophenylthio(ethane. The structures of the complexes have been elucidated by elemental analyses, molar conductance, magnetic susceptibility measurements, i.r., electronic and e.p.r. spectral studies. The complexes are of the high spin type and are six-coordinate.     

Circular dichroism of the complexes of quinine with copper(II), nickel(II), cobalt(II), chromium(III) and palladium(II) chlorides

The CD spectrum of the complexesQ·2CuCl₂,Q·2CoCl₂,Q·2NiCl₂·8H₂O,Q·3CrCl₃·6H₂O,Q·PdCl₂·3H₂O andQ·2PdCl₂·5H₂O (whereQ=quinine) inDMF orDMSO solution revealsCotton effects in the d-d absorption range. TheCotton effects are relatively strong in the case of Cu(II) and Pd(II) complexes which implies that only in these complexes the hydroxyl group of the quinine molecule possibly participates in the coordination with these metal ions by formation of a chelate ring. The IR spectra of the complexes of Pd(II) are discussed in this respect.

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Circular Dichroismus der Komplexe des Chinins mit Kupfer(II)-, Nickel(II)-, Kobalt(II)-, Chrom(III)- und Palladium(II)-chlorid

Zusammenfassung Die CD-Spektren der KomplexeQ·2CuCl₂,Q·2CoCl₂,Q·2NiCl₂·8H₂O,Q·3CrCl₃·6H₂O,Q·PdCl₂·3H₂O undQ·2PdCl₂·5H₂O, (Q=Chinin), inDMF-bzw.DMSO-Lösungen zeigenCotton-Effekte im Gebiet der d-d-Elektronenübergänge. DieCotton-Effekte sind relativ stark im Falle der Cu(II)- und Pd(II)-Komplexe, was zu der Annahme führt, daß die Hydroxygruppe des Chininmoleküls in diesen Komplexen wahrscheinlich an der Koordination dieser Metallionen durch Chelatringbildung teilnimmt. Unter diesem Aspekt werden die IR-Spektren der Pd(II)-Komplexe untersucht.

     

Monomeric dioxouranium(VI), chromium(III), cobalt(II), nickel(II) and copper(II) complexes with primary cellulose acetate (PCA)

Monomeric UO ₂ ²⁺ , Cr^III, CO^II, Ni^II and Cu^II complexes with primary cellulose acetate (PCA) have been prepared and characterized. Infrared,¹H NMR, UV/visible spectroscopy, elemental analysis, therniogravimetry, conductance and magnetic measurements were used to assign the mode of coordination in the isolated species. The investigation revealed that PCA exhibits octahedral coordination with Cr^III, Co^II, Ni^II and a square planar form with Cu^II whereas the UO₂ moiety is virtually linear. PCA acts as a neutral bidentate chelating agent via the two oxygen atoms of the vicinal ester groups in the secondary positions forming a five-membered chelate ring. A comparative study between chelates of PCA and those previously prepared with secondary cellulose acetate (SCA) has been undertaken.     

Synthesis and spectral properties of new complexes between glycine and titanium(III), vanadium(III), chromium(III), iron(III), cobalt(II), nickel(II) and copper(II)

Summary Complexes of formula [MCl₃(glyH)₃] (M=Ti, V and Fe) [CrCl₃(glyH)₂H₂O], [MCl₂(glyH)₂(H₂O)₂] (M=Co and Cu) and [NiCl₂(glyH)₃H₂O] have been prepared and characterized by potentiometric curves, chemical analysis, magnetic properties, i.r. and electronic spectral data.     

Spectroscopic characterization of chromium(III), manganese(II) and nickel(II) complexes with a nitrogen donor tetradentate, 12-membered azamacrocyclic ligand

The complexes of Cr(III), Mn(II) and Ni(II) were synthesized with macrocyclic ligand i.e. 5,11-dimethyl-6,12-diethyl-dione-1,2,4,7,9,10-hexazacyclododeca -1,4,6,10-tetraene. The ligand (L) was prepared by [2+2] condensation reaction of 2,3-pentanedione and semicarbazide hydrochloride. These complexes were found to have the general composition [Cr(L)X(2)]X and [M(L)X(2)] (where M=Mn(II) and Ni(II); X=Cl(-), NO(3)(-), (1/2)SO(4)(2-), NCS(-) and L=ligand [N(6)]). The ligand and its transition metal complexes were characterized by the elemental analysis, molar conductance, magnetic susceptibility, mass, IR, electronic and EPR spectral studies. On the basis of IR, electronic and EPR spectral studies, an octahedral geometry has been assigned for these complexes except sulphato complexes which are of five coordinated geometry.     

Spectroscopic studies on chromium(III), manganese(II), cobalt(II), nickel(II) and copper(II) complexes with hexadentate nitrogen-sulfur donor [N(2)S(4)] macrocyclic ligand

Complexes of transition metals have been synthesized with hexadentate ligand (2,6-bis(((2-mercaptophenyl)thio)methyl)pyridinato)metal(II). These complexes have been synthesized via the two step template reaction by using the benzene dithiol, 2,6-bis(chloro)methyl pyridine and corresponding metal salt as key raw materials. The structures of the complexes have been elucidated on the basis of elemental analysis, molar conductance measurements, magnetic susceptibility measurements, IR, electronic and EPR spectral studies. All of the complexes were found to possess six-coordinated geometry and are of high spin type.     

Synthesis,characterization and susceptibility of bacteria against Sulfamethoxydiazine complexes of copper(II), zinc(II), nickel(II), cadmium(II), chromium(III) and iron(III)

Complexes of sulfamethoxydiazine with Cu(II), Zn(II), Ni(II), Cd(II), Cr(III) and Fe(III) have been synthesized and characterized on the basis of conductivity measurements, elemental analyses, UV, IR, ¹H?NMR and thermal studies. It is shown that sulfamethoxydiazine behaves as a bidentate ligand, binding the metal ion through the sulfonyl oxygen and sulfonamide nitrogen. In vitro susceptibility tests of these complexes against Escherichia coli, Bacillus subtilis, Proteus vulgaris and Staphylococcus aureus were carried out. The results show that the antibacterial activities of the complexes of Zn(II), Cu(II), Cr(III) and Fe(III) are, in general, stronger than that of sulfamethoxydiazine, while the complexes of Cd(II) and Ni(II) are less active.     

New copper(II), manganese(III), nickel(II) and zinc(II) complexes with a chiral quadridentate Schiff base

A chiral Schiff base ligand (H₂L) was obtained by condensing 2-hydroxynaphthalene-1-carbaldehyde with substituted (1R,2R)-(–)-diaminocyclohexane. Chiral Schiff base complexes [CuL], [NiL], [ZnL] and [MnLOH] have been synthesized and characterized by elemental analyses, _M, i.r., u.v.–vis. and ¹H-n.m.r. and magnetic measurements.     

Spectroscopic approach in characterization of chromium(III), manganese(II), iron(III) and copper(II) complexes with a nitrogen donor tetradentate, 14-membered azamacrocyclic ligand

The complexes of Cr(III), Mn(II), Fe(III) and Cu(II) were synthesized with the macrocyclic ligand i.e. 2,3,9,10-tetraketo-1,4,8,11-tetraazacyclotetradecane. The ligand was prepared by the [2 + 2] condensation reaction of diethyloxalate and 1,3-diamino propane. These complexes were found to have the general composition M(L)X3 and M'(L)X2 [where M = Mn(II) and Cu(II), M' = Cr(III) and Fe(III), L = ligand (N4) and X = Cl-, NO3-, 1/2SO4(2-) and [CH3COO-]. The ligand and its transition metal complexes were characterized by the elemental analyses, molar conductance, magnetic susceptibility, mass, IR, electronic, and EPR spectral studies. On the basis of IR, electronic and EPR spectral studies an octahedral geometry has been assigned for Cr(III), Mn(II) and Fe(III) and a tetragonal geometry for Cu(II) complexes.     

Cobalt(III), nickel(II), and copper(II) complexes of 1-thia (or oxa)4,7-diazacyclononane and related mixed-ligand cobalt(III) complexes

Summary To investigate the effect of substitution of an oxygen or a sulphur donor atom for a nitrogen donor atom in a cyclic triamine, 1,4,7-triazacyclononane (tacn), cobalt(III), nickel(II), and copper(II) complexes of 1-oxa-4,7-diazacyclononane (taon) and 1-thia-4,7-diazacyclononane (tasn), and related mixed ligand cobalt(III) complexes were prepared and characterized. The coordination ability of an ether-oxygen or a thioether-sulphur atom increases when these atoms are incorporated into cyclic terdentate ligands. Electronic spectra reveal that ligand field strengths of these atoms are enhanced significantly. The presence of these heteroatoms affects circular dichroism spectra because of the increased flexibility of the chelate rings.     

Cobalt(III), copper(II), and nickel(II) complexes of 1-thia-4,7-diazacyclononane-S-oxide

Summary The title complexes [ML₂]ⁿ⁺=Co^III, Cu^II, Ni^II; L=1-thia-4,7-diazacyclononane-S-oxide) have been prepared and characterized spectroscopically. The sulphoxide group is coordinated through the oxygen atom and the complexes have atrans-O,O geometry. The nickel(II) complex of bis(2-amino-ethyl)sulphoxide has also been studied.     

Half-sandwich Ru(II), Ir(III) and Rh(III) complexes with bridging or chelating N-heterocyclic bis-carbene ligand: Synthesis and characterization

N-heterocyclic bis-carbene ligand (bis-NHC) which was derived from 1,1′-diisopropyl-3,3′-ethylenediimidazolium dibromide (L·2HBr) via silver carbene transfer method, reacted with [(η⁶-p-cymene)RuCl₂]₂ and [Cp^∗MCl₂]₂ (Cp^∗ = η⁵-C₅Me_5, M = Ir, Rh) respectively, afforded complexes [(η⁶-p-cymene)RuCl₂]₂(L) (1), [Cp^∗IrCl₂]₂(L) (2) and [Cp^∗RhCl(L)][Cp^∗RhCl₃] (3). When [Cp^∗IrCl₂]₂ was treated with 2 equiv AgOTf at first, and then reacted with bis-NHC ligand, [Cp^∗IrCl(L)]OTf (4) was obtained. The molecular structures of complexes 1-4 were determined by X-ray single crystal analysis, showing that 1 and 2 adopted bridging coordination mode, 3 and 4 adopted chelating coordination mode. All of these complexes were characterized by ¹H, ¹³C NMR spectroscopy and element analysis.     

Synthesis and spectral studies of chromium(III), cobalt(II) and nickel(II) complexes with phenylhydrazonoamidoxime

Summary Mononuclear complexes of chromium(III), nickel(II) and cobalt(II) derived from 3-oxo-2-phenylhydrazonobutane1-carbamidoxime (OPCA) were prepared and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements and electronic and i.r. studies. The chromium(III) and nickel(II) ions form 1:2 complexes, whereas cobalt(II) forms a 1:1 complex in which the ligand chelates through the nitrogen of the amidoxime and the carbonyl oxygen. An octahedral structure is assigned to these complexes and the ligand field parameters such as Dq, B and were calculated. The nephelexautic parameter, , has values of 0.68, 0.84 and 0.78 for the chromium(III), cobalt(II) and nickel(II) complexes, respectively, suggesting the presence of covalent metal-ligand -bonds.     

Chromium(III), manganese(II), cobalt(II), nickel(II), copper(II) and palladium(II) complexes of a 12-membered tetraaza [N4] macrocyclic ligand

Cr^III, Mn^II, Co^II, Ni^II, Cu^II and Pd^II complexes of the macrocyclic ligand, 2,3,5,8,9,11 hexamethyl-1,4,7,10 tetraaza- cyclododeca-1,3,7,9 tetraene (DADAP), have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, i.r., electronic and e.p.r. spectral studies. These spectral studies suggest an octahedral geometry for the Cr^III, Mn^II and Co^II, square planar geometry for Ni^II and Pd^II and tetragonal geometry for Cu^II complexes.     

Polynuclear copper (II) complexes with aminoalcohol ligands

Copper complexes with aminoalcoholato ligands have attracted much attention recently because of their potential applications in ceramic materials. This review deals with polynuclear copper (II) complexes containing bidentate and triden-tate aminoalcoholato ligands. The focus of this article is on the synthesis, structure, and magnetic properties of polynuclear copper (II) complexes obtained recently by our group. Some relevant work reported previously by other researchers is also included.Dedicated to Professor Jiaxi Lu on the occasion of his 80th birthday.     

Cobalt(II), nickel(II) AND zinc(II) dicarboxylate complexes with hydrazine as bridged ligand

The complexes of chromium and molybdenum with salicylidene-2-aminophenol (shaH₂), salicylidene-2-aminoanisole (salanH₂), salicylidene-2-aminoaniline (salphenH₂) and biquinoline (biq) were studied using the thermogravimetric techniques. The thermal decomposition of all complexes was found to be first order reaction and the thermodynamic parameters corresponding to the different decomposition steps were reported. Molybdenum complexes were found to be more thermally stable and the order of stability was [Mo(CO)₄(biq)]>[MoO(salphen)]>[MoO₂(salphenH)₂]>[MoO₄(salan)₂]>[MoO(sha)]. Similar trend was found for chromium complexes where [Cr(CO)₄(biq)]>[Cr(CO)₂(salphen)] >[CrO₂(CO)₂(shaH₂)]>[CrO₂(CO)₂(salan)₂].     

Ternary complexes of copper(II), nickel(II) and zinc(II) with nitrilotriacetic acid as a primary ligand and some phenolic acids as secondary ligands

Summary The formation of ternary complexes of the MAL^3– type [where M = Cu^II, Ni^II and Zn^II ; A = nitrilotriacetic acid (NTA); L = 1-hydroxy-2-naphthoic acid (1,2 HNA) and 2-hydroxy-1-naphthoic acid (2,1 HNA)] have been studied potentiometrically in 50% v/v aqueous — ethanol (25° and µ = 0.1). Under identical conditions the binary complexes of the 1,2- and 2,1-HNA ligands have also been examined. The values of mixed ligand formation constants K_MAL have been found to be lower than K_ML (first step formation constant of binary complexes) and even less than (second step formation constant of binary complexes).     

Complexes of 1-isonicotinoyl-4-benzoyl-3-thiosemicarbazide with manganese(II), iron(III), chromium(III), cobalt(II), nickel(II), copper(II) and zinc(II)

1-Isonicotinoyl-4-benzoyl-3-thiosemicarbazide (IBtsc) and its Cr^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II and Zn^II complexes have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, u.v.–vis., i.r., n.m.r. and FAB mass spectral data. The room temperature e.s.r. spectra of the Cr^III, Fe^III and Cu^II complexes yield values, characteristic of octahedral, tetrahedral and square-planar complexes, respectively. The Mössbauer spectra of [Fe(IBtsc-H)Cl₂] at room temperature and at 78 K suggest the presence of high-spin Fe^III. The Ni^II, Cr^III and Cu^II complexes show semiconducting behaviour in the solid state, but the Zn^II complex is an insulator at room temperature. IBtsc and its soluble complexes have been screened against several bacteria, fungi and tumour cell lines.     

Synthesis and characterization of mixed ligand complexes of copper(II), nickel(II), cobalt(II) and zinc(II) with glycine and uracil or 2-thiouracil

Mixed ligand complexes of Cu(II), Ni(II), Co(II) and Zn(II) formed with glycine and uracil or 2-thiouracil have been synthesized and characterized by elemental analysis, conductance, spectral (IR and electronic spectra) and magnetochemical measurements. Results show that glycine is bidentate in all cases; uracil behaves as a bidentate ligand in Cu(II) complex, coordinating through its one carbonyl oxygen and nitrogen, whereas in other cases it is only monodentate, coordinating only through nitrogen. With thiouracil, coordination occurs from carbonyl oxygen and one nitrogen in Cu(II) and Ni(II) complexes, but in the Co(II) complex coordination occurs from thionyl sulphur and nitrogen. In the Zn(II) complex it shows tridentate behaviour, coordinating through oxygen, sulphur and one nitrogen. Mixed Cu(II), Co(II) and Zn(II) complexes of uracil and of Ni(II) and Zn(II) with thiouracil are octahedral, whereas the mixed Ni(II) complex with uracil shows distorted tetrahedral geometry, and the mixed Co(II)-thiouracil complex is square planar. The mixed Cu(II)-thiouracil complex has a binuclear structure, with square planar arrangement around each copper atom.