Synthesis and characterization of 5-(arylazo)thiobarbituric acids and their complexes

Summary S-(Arylazo)thiobarbituric acids and their complexes, derived from cobalt(II), nicke(II) and copper(II) were characterized by elemental analyses and spectral measurements. The¹H n.m.r. and i.r. spectra show the ligands to be in the keto-thione form. The strength of the intramolecular hydrogen-bonding is influenced by the electronic requirements of the aryl ring substituents.     

Synthesis and characterization of new complexes of some divalent transition metals with 2-acetyl-pyridyl-isonicotinoylhydrazone

Ten new mononuclear complexes having general formulae [ML₂](ClO₄)₂, M = Cu(II), Co(II), Ni(II), Mn(II) and Zn(II), [ML₂](SO₄), M = Co(II), Ni(II) and [ML₂(H₂O)₂](SO₄), M = Cu(II), Mn(II) and Zn(II), L = 2-acetyl-pyridyl-isonicotinoylhydrazone have been synthesized and characterized based on elemental analyses, IR spectroscopy, UV–Vis–NIR, EPR, as well as thermal analysis and determination of molar conductivity and magnetic moments. The structures of [CoL₂](ClO₄)₂ are accomplished by single crystal X-ray diffraction. The coordination sphere is formed by two N, N, O tridentates 2-acetyl-pyridyl-isonicotinoylhydrazone ligands, or by two N, O bidentate 2-acetyl-pyridyl-isonicotinoylhydrazone and two water molecules. Biological activity studies reveal a moderate activity of complexes against gram-negative and gram-positive bacteria.     

Synthesis,characterization and antimicrobial activity of 5‐(arylazo)salicylaldimines and their copper(II) complexes

A new series of twelve bidentate Schiff's base ligands (HL^1–12) was synthesized via condensation of 5‐(arylazo)salicylaldehydes with aromatic amines. When the new salicylaldimine derivatives were reacted with copper(II) chloride, the neutral complexes Cu(L^1–12)₂ were obtained. The structure of the copper complexes was established from microanalyses, IR and UV spectra and thermal analyses. The results suggested that the ligands were coordinated to the metal ion in a bidentate manner with ON donor sites of the deprotonated phenolic‐OH and azomethine‐N. The composition of the complexes can be represented as CuL₂. Evaluation of antimicrobial activity for the synthesized compounds was carried out to probe their activity. The compounds were found to have weak antimicrobial activity.     

Synthesis and characterization of substituted aminobiphenylglyoximes and their complexes with some transition metals

In this study, four different new vic-dioximates, [L¹H₂] N-(4-ethylphenyl)amino-biphenylglyoxime, [L²H₂] N-(4-butylphenyl)aminobiphenylglyoxime, [L³H₂] N-(4-aminoacetanilide)aminobiphenylglyoxime, and [L⁴H₂] N-(thiazol-2-yl-aminobiphenylglyoxime are synthesized from anti-4′-biphenylchloroglyoxime and the corresponding substituted aromatic amines. The Co(II), Ni(II), and Cu(II) complexes of these ligands are prepared. The structures of these new ligands and their complexes are proposed based upon IR, ¹H, and ¹³C NMR spectral data, mass spectroscopy, magnetic susceptibility measurement, and elemental analyses. The text was submitted by the authors in English.     

Transition metal (disubstituted phenylazo)-barbituric and thiobarbituric acid complexes

Summary Disubstituted phenylazo-barbituric and thiobarbituric acid complexes derived from Co^II, Ni^II and Cu^II salts have been prepared. Electronic spectra and magnetic susceptibility measurements prove that the cobalt and nickel complexes have high-spin octahedral and square planar configurations, respectively. The copper-barbituric complexes have distorted octahedral geometry with a possible Cu–Cu interaction, whereas the corresponding thiobarbiturate complexes have square pyramidal distorted octahedral and tetragonal geometries. The room temperature e.s.r. spectra of the copper complexes show anisotropy with axial symmetry in tetragonal geometry, ground state as a result of Cu–Cu interaction. This dimeric structure disappears in DMSO solution. The intradimer super-exchange interaction is temperature dependent indicating a change of the geometry. In some complexes, the azo group coordinates to the metal, in others it does not. The denticity of the ligands has been determined.     

Synthesis, spectral characterization and redox properties of iron (II) complexes of 1-alkyl-2-(arylazo)imidazole

Iron (II) complexes of 1-alkyl-2-(arylazo)imidazoles (p-R-C₆H₄-N=N-C₃H₂NN-1-R′, R = H (a), Me (b), Cl (c) and R′ = Me (1/3), Et (2/4) have been synthesized and formulated astris-chelates Fe(RaaiR′) ₃ ²⁺ . They are characterized by microanalytical, conductance, UV-Vis, IR, magnetic (polycrystalline state) data. The complexes are low spin in character,t _2g ⁶ (Fe(II)) configurations.     

Synthesis and characterization of the complexes of some transition metals with 2-acetyl pyridine (N-benzoyl) glycyl hydrazone

Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) with 2-acetyl pyridine (N-benzoyl) glycyl hydrazone(2-ApBzGH) have been synthesized and characterized by elemental analyses, molar conductances, magnetic susceptibility, IR, electronic, ESR,¹H,¹³C and¹¹³Cd NMR spectral and X-ray diffraction studies. IR and NMR data suggest the tridentate nature of the ligand coordinating as a neutral species in the addition complexes and as a uninegative species in the deprotonated complexes. The presence of more than one isomer of the ligand has been established by¹H NMR spectra of the ligand and complexes recorded over the 298–396 K range. The X-ray powder diffraction patterns of [Cd(2-ApBzGH)Cl]Cl and [Cu(2-ApBzGH)Cl(H₂O)₂]Cl are indexed for orthorhombic and tetragonal crystal systems respectively.     

Synthesis,characterization and reactivity of electrophilic mononitrosyls of 2-(arylazo)pyridineosmium(II)

High yield synthetic routes to osmium mononitrosyls of the type [OsX(NO)L2]2+ [L=2-(arylazo)pyridine; X=NO2, (2) and Cl/Br, (4)], isolated as their perchlorates, are described. In alkaline media they regenerate the corresponding nitrite precursors (1) and (3), respectively. The diamagnetic orange–red nitrosyls exhibit (NO) at ca. 1925 cm–1, indicating a high degree of NO+ character. Several spin-allowed and spin-forbidden transitions are observed in the 1000–200 nm region. The complexes are electroactive, showing typical metal-centred oxidation and NO+ and L reductions. Reactions with inorganic/organic nucleophiles such as azide and acetylacetone clearly establish the electrophilic nature of the bound nitrosyl group.     

Synthesis and electrochemical characterization of complexes of 1,2-bis[2-(pyridylmethylideneamino)phenylthio]ethanes with transition metals (CoII, NiII, CuII)

Transition metal (Ni^II, Co^II, and Cu^II) complexes with 1,2-bis[2-(3-pyridylmethylideneamino)phenylthio]ethane (1) and 1,2-bis[2-(4-pyridylmethylideneamino)phenylthio]ethane (2) were synthesized for the first time by slow diffusion of solutions of compounds 1 or 2 in CH₂Cl₂ into solutions of MX₂ · nH₂O (M = Ni, Co, or Cu; X = Cl or NO₃; n = 2 or 6) in ethanol. The reactions with Co^II and Cu^II chlorides afford complexes of composition M(L)Cl₂ (L = 1 or 2). The reactions of compound 1 with Ni^II salts produce complexes with 1,2-bis(2-aminophenylthio)ethane. The molecular structure of dinitrato[1,2-bis(2-aminophenylthio)ethane]nickel(ii) was confirmed by X-ray diffraction. The ligands and the complexes were investigated by cyclic voltammetry and rotating disk electrode voltammetry. The initial reduction of the complexes proceeds at the metal atom. The oxidation of the chlorine-containing complexes proceeds at the coordinated chloride anion. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–355, February, 2008.     

Synthesis, characterization and antiproliferative activity of transition metal complexes with 3-(4,5-diphenyl-1,3-oxazol-2-yl)propanoic acid (oxaprozin)

A series of novel Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with oxaprozin (Hoxa), a non-steroidal anti-inflammatory drug, has been synthesized. The drug and complexes have been characterized by elemental and thermogravimetric (TG) analysis, Fourier transform (FT)-IR, 1H-NMR, 13C-NMR, UV-Vis spectroscopy and magnetic susceptibility measurements. The (pseudo)octahedral geometry has been proposed for all complexes based on electronic spectra and magnetic moments. With exception of the Cu(II) complex, where bridging bidentate mode of COO groups has been found, FT-IR spectra confirmed chelately coordinated COO groups in the other complexes. The general formula of the complexes is [M(H2O)2(oxa)2 ·χH2O, with χ=2 for M=Mn, Co and Ni and χ=1.5 for Zn. The binuclear Cu(II) complex, [Cu2(H2O)2(OH)(oxa)3]·2H2O, has strong Cu-Cu interactions of antiferromagnetic type. The complexes and Hoxa did not exhibit the cytotoxic effect to peritoneal macrophages. For the first time these complexes have been tested for their in vitro antiproliferative activity against human colon and breast cancer cell lines, HCT-116 and MDA-231, respectively. For all investigated compounds significant antiproliferative effects have been observed. Ni(II) complex has been shown to be a promising antiproliferative agent exerting excellent activity against HCT-116 even in nanomolar concentrations.     

Synthesis, characterization and liquid–liquid extraction properties of new methoxyaminobiphenylglyoxime derivatives and their complexes with some transition metals

In this study, three new aminobiphenylglyoximes, [L¹H₂] N-(2-methoxy)aminobiphenylglyoxime, [L²H₂] N-(3-methoxy)aminobiphenylglyoxime and L[³H₂] N-(4-methoxy)aminobiphenylglyoxime have been synthesized by the reaction of (E,E)-4′-biphenylchloroglyoxime with 2-Methoxyaniline, 3-Methoxyaniline and 4-Methoxyaniline in absolute ethanol. The preparation Ni^II, Co^II and Cu^II complexes of these ligands are described. The ligands and their complexes were characterized by elemental analyses, IR, mass, H¹ and ¹³C NMR spectra, thermogravimetric analyses (t.g.a) and magnetic susceptibility measurements. Ligands complexing properties were studied by the liquid–liquid extraction of selected alkali (Li⁺, Na⁺, K⁺, Cs⁺) and transition metals (Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺). It has been observed that all ligands show a high affinity to Cu²⁺ ions, whereas almost no affinity to alkali metals. The extraction equilibrium constants (K _ex) for complexes of ligands with Cu²⁺ metal picrates between dichloromethane and water have been determined at 25°C.     

Synthesis and characterization of transition metal complexes of a new bidentate ligand {2-(diphenylphosphino)ethyl}benzylamine

A new bidentate ligand {2-(diphenylphosphino)ethyl}benzylamine(DPEBA) was synthesized and characterized based on the IR, mass and ¹H, ¹³C and ³¹P NMR spectra. Various complexes of platinum group metal ions and Ni(II) and Co(II) ions with the ligand were synthesized. Reaction of RuCl₂(PPh₃)₃ or RuCl₂(Me₂SO)₄ with the ligand DPEBA, resulted in formation of a penta-coordinate, Ru(II) species of the composition [RuCl(DPEBA)₂]Cl. Carbonylation of [RuCl(DPEBA)₂]Cl gave an octahedral carbonyl complex of the type [RuCl(CO)(DPEBA)₂]Cl. The reaction of RuCl₃·3H₂O or RuCl₃(AsPh₃)₂MeOH with a twofold excess of the ligand gave an octahedral Ru(III) cationic species [Ru(DPEBA)₂Cl₂]Cl. Carbonylation of the Ru(III) complex gave rise to a carbonyl complex [RuCl(CO)(DPEBA)₂]Cl₂. The ligand DPEBA reacts with cobalt(II) chloride in methanol to give the 1 : 1 complex [Co(DPEBA)Cl₂]. A series of Rh(I) complexes [Rh(DPEBA)₂Cl], [ RhCl(CO)(DPEBA)] and [Rh(DPEBA)₂]Cl were synthesized by the reaction of DPEBA with RhCl(PPh₃)₃, RhCl(CO)(PPh₃)₂ and [Rh(COD)Cl]₂, respectively. Reaction of [Ir(COD)Cl]₂ and IrCl(CO)(PPh₃)₂ with the ligand DPEBA, gave the square-planar complexes [Ir(DPBA)₂]Cl and [Ir(DPEBA)(CO)Cl], respectively. Octahedral cationic complexes of the type [M(DPEBA)₂Cl₂]Cl (M = Rh(III), Ir(III)) were synthesized by the reaction of the ligand DPEBA and rhodium and iridium trichlorides. Reaction of NiCl₂·6H₂O with DPEBA in 1 : 2 molar equivalents, in boiling butanol gave an octahedral neutral complex [Ni(DPEBA)₂Cl₂] which readily rearranges to the square-planar complex [Ni(DPEBA)₂]Cl₂ in methanol. Reaction of Pd(II) and Pt(II) chlorides with DPEBA gave square-planar, cationic complexes of the type [M(DPEBA)₂Cl]Cl (M = Pd, Pt). All the complexes were characterized on the basis of their analytical and spectral data.     

Synthesis and structural characterization of palladium(II) 2-(arylazo)naphtholate complexes and their catalytic activity in Suzuki and Sonogashira coupling reactions

Abstract

A family of five palladium(II) 2-(arylazo)naphtholate complexes, [PdCl(PPh₃)(L)] (L?=?O, N-donor of bidentate 2-(arylazo)naphtholate ligands), have been synthesized and characterized by elemental analysis and spectral (FT-IR, UV–Vis, ¹H-NMR and ¹³C-NMR) methods. Further, the catalytic efficiency of all the complexes have been investigated for Suzuki and Sonogashira coupling reaction of various aryl halides.     

Chemistry of 2-(arylazo)phenolate complexes of ruthenium. Synthesis,structure and reactivities

A group of six ruthenium(III) complexes of type [Ru(acac)(L)₂]where acac=acetylacetonate anion and L=2-(arylazo)-4-methylphenolate anion or 1-(phenylazo)-2-naphtholate anion have been synthesized and characterized Structural characterization of a representative complex where L=1-(phenylazo)-2-naphtholate anionshows that the azophenolate ligands are coordinated as NO-donor ligands forming six-membered chelate rings The complexes are paramagnetic (low-spin d⁵S=1/2) and show rhombic ESR spectra in 1:1 dichloromethane–toluene solution at 77 K In carbon tetrachloride solution these complexes show intense LMCT transitions in the visible region together with weak ligand-field transitions in the near-IR region All the complexes display two cyclic voltammetric responses a ruthenium(III)–ruthenium(IV) oxidation in the range of 083 to 103 V vs SCE and a ruthenium(III)–ruthenium(II) reduction in the range of −024 to −052 V vs SCE Formal potentials of both the couples correlate linearly with the Hammett constant of the para substituent in the arylazo fragment of the 2-(arylazo)-4-methylphenolate ligand The ruthenimn(IV) and ruthenium(II) congeners of the [Ru^III(acac)(L)₂] complexes have been generated by chemical or electrochemical methods and they have been characterized by electronic spectroscopy and cyclic voltammetry.     

Synthesis,characterization, and anti-tumor activities of some transition metal(II) complexes with podophyllic acid hydrazide

Four transition metal(II) complexes with podophyllic acid hydrazide (HL) were prepared and characterized by elemental analysis, complexometric titration, thermal analysis, conductivity, IR, and ¹H NMR. The complexes have the general formula ML₂ · nH₂O, where M = Zn, Cu, Co, and Ni, n = 2 or 0. Anti-tumor activities of podophyllotoxin, HL, ZnL₂ · ₂H₂O, and NiL₂ were tested by both the MTT and the SRB method. The results show that the activities of the complexes against the tumor cells tested are superior to HL and the anti-tumor activity of NiL2 is even similar to that of podophyllotoxin.     

Synthesis,characterization, and thermal analysis of ternary complexes of nitrilotriacetic acid and alanine or phenylalanine with some transition metals

Ternary complexes of Co(II), Ni(II), Cu(II), and Zn(II) with nitrilotriacetic acid as a primary ligand and alanine or phenylalanine as secondary ligand were prepared in slightly acidic medium. The structures of the complexes were elucidated using elemental, IR, molar conductance, magnetic moment, UV–Vis spectrophotometry, and thermal analyses. The ternary complexes were isolated in 1:1:1 (M:HNTA:alaH) ratios, and the molecular structures were found to be [M(HNTA)(alaH)(H₂O)₂]. Thermogravimetric analysis confirmed this structure and that the water present is coordinated to the central metal atom. UV–Vis spectra showed that the complexes have octahedral symmetry.     

Recent advances on the chemistry of transition metal complexes of 2-(arylazo)pyridines and its arylamino derivatives

Recent advancement on the redox properties of a selection of transition metal complexes of the azoaromatic ligands: bidentate L(1) [2-(arylazo)pyridine] and tridentate HL(2) [2-(aminoarylphenylazo)pyridine] are described and compared. Due to the presence of a low lying azo-centered π*-orbital, these azoaromatic ligands may exist in multiple valent states. The coordination chemistry of the L(1) ligands was thoroughly studied during the 1980s. These complexes undergo facile reduction in solution at low accessible potentials. One electron reduced azo-complexes, though known for a long time to occur in solution, have only recently been isolated in a crystalline state. New synthetic protocols for the synthesis of metal-bound azo-radical complexes have been developed. Low-valent metal complexes such as metal carbonyls have been found to be excellent starting materials for this purpose. In a few selected cases, syntheses of these complexes were also achieved from very high valent metal oxides using triphenylphosphine as both a reducing and oxo-abstracting agent. Issues related to the ambiguities of the electronic structures in the azo-metal complexes have been discussed considering bond parameters, redox and spectral properties. Unusual redox events such as RIET (Redox-Induced Electron Transfer) phenomena in a few systems have been elaborated and compared with the known example. Novel examples of N=N bond cleavage reactions via four-electron reduction and subsequent C-N bond formation in metal-bound coordinated ligands have been noted.     

Synthesis, characterization and properties of some metal(II) 5-(nicotinamido)isophthalate complexes

Four new complexes, {[M(NAIP)(H₂O)₄]·2H₂O}_n (M = Co (1), M = Mn (2)), {[Zn(NAIP)]·0.5H₂O}_n (3) and {Cd(NAIP)(H₂O)₂]·1.5H₂O}_n (4) [H₂NAIP = 5-(nicotinamido)-isophthalic acid] have been prepared and structurally characterized. The ligand NAIP²⁻ exhibits different coordination modes and leads to the formation of various architectures. Complexes 1 and 2 show a one-dimensional (1D) zigzag chain, where hydrogen-bonding interactions further link these chains to a three dimensional (3D) supramolecular structure. For complex 3, a 3D coordination network with a four-coordinated Zn(II) and NAIP²⁻ as a SBU was observed. Complex 4 presents a three-connected 2-fold interpenetrated 3D network with a (10, 3)-b net topology. Their luminescent and magnetic properties have been investigated in the solid state.