Synthesis and structure of new copper(II) coordination compounds with 8-quinoline aldehyde semicarbazones and thiosemicarbazones

Copper(II) salts were reacted with various quinoline aldehyde chalcogensemicarbazones to yield compounds formulated as Cu(HL)X₂ · nH₂O (I: HL = quinoline aldehyde thiosemicarbazone (HL¹), X = ClO₄, n = 2; II: HL = quinoline aldehyde 4-C₂H₅-thiosemicarbazone (HL^1a), X = NO₃, n = 0; III: HL = quinoline aldehyde semicarbazone (HL²), X = ClO₄, n = 3 and IV: HL = quinoline aldehyde 4-Ph-semicarbazone (HL^2a), X = NO₃, n = 1). Regardless of the reagent ratio, the products were compounds having the metal: ligand ratio of 1: 1, where the organic ligand was coordinated tridentate in a molecular form. Single-crystal X-ray diffraction showed that, depending on the chalcogen atom in the organic ligand (S or O), the substituent in the 4th position (at the terminal nitrogen atom), and the specifics of the acido ligand, complexes I–IV had appreciably differing molecular structure organizations. The structures of I and III are formed by a 1D charged coordination polymer, ClO ₄ ^? anions, and water molecules and may be described by the formula [Cu(HL)(H₂O)(ClO₄)] _n (ClO₄) _n · nH₂O. Copper(II) coordination polyhedra in I and II are (4 + 2) and (4 + 1 + 1) tetragonal bipyramids, respectively. In II and IV, the structures are monomeric and can be described as [Cu(HL^1a)(NO₃)₂] with the metal coordination polyhedron shaped as a (4 + 1) tetragonal pyramid in II and as [Cu(HL^2a)(H₂O)(NO₃)](NO₃) with the metal coordination polyhedron shaped as a (3 + 2) trigonal bipyramid in IV. The structure of II is built of molecular complexes, each comprising, apart from ligand HL^1a, two monodentate coordinated NO ₃ ^? groups. The oxygen atom of one anion together with the NNS donor atom set of ligand HL^1a form the base, and the oxygen atom of the other anion is in the apex of the coordination polyhedron. In IV, the structure is ionic and built of NO ₃ ^? anions and [Cu(HL^2a)(H₂O)(NO₃)]⁺ complex cations, where a cationic coordination polyhedron has a trigonal-bipyramidal configuration with organic ligand HL^2a positioned along the long edge. The bipyramidal base is made up by the oxygen atoms of the coordinated water molecule and monodentate nitrato group and the nitrogen atom N2 of the azomethyne group.     

Synthesis and study of the structure of new 3d-metal coordination compounds with substituted 2-amino-4(5H)-ketothiophens

A series of new 3d-metal complexes based on 2-amino-3-(1-methylbenzimidazol-2-yl)-4(5H)-ketothiophen (HL¹) and 2-amino-3-(2-benzothiazolyl)-4(5H)-ketothiophen (HL²) were synthesized. Compounds of the general formulas [ML₂] and [M(HL¹)₂Cl₂] (where M = Co²⁺, Ni²⁺, Zn²⁺, Cu²⁺) were prepared by the reaction of the above mentioned ligands with the corresponding acetate (for [ML₂]) or chloride (for [M(HL¹)₂Cl₂]) salts in a methanol or a methanol–chloroform medium. The choice of the anion in the initial metal salt, as well as the selection of the ligand, is crucial for obtaining coordination compounds with a neutral or deprotonated form of the 2-amino-4(5H)-ketothiophens. Thus, in contrast to HL¹, complexes with the neutral form of HL² cannot be obtained under the same conditions. All the complexes were studied by spectroscopic methods and X-ray crystallography (for [CuL¹₂] · H₂O). The coordination polyhedron of the copper atom is formed by four nitrogen atoms from two ligand anions and the geometry of the coordination sphere is intermediate between tetrahedral and square-planar.     

Co(II), Ni(II), and Cu(II) Complexation with Isatin Aminoguanisone and Nitroaminoguanisone

New complexes of bivalent Co, Ni, and Cu with isatin aminoguanisone (HL) and nitroaminoguanisone (HL¹) of the composition ([Co(HL)₂]Cl₂ (I), [Ni(HL)₂]Cl₂ (II), [Cu(L)Cl] (III), [Co(L¹)₂] (IV), [Ni(L¹)₂] (V), and [Cu(L¹)₂] (VI) are synthesized. Their molecular conductivities and effective magnetic moments are measured and thermal stabilities are studied. The type of the ligand coordination in I–VI is proposed on the basis of IR data. The summary of physicochemical data for I–VI and the energy calculations for their molecules by the molecular mechanics method made it possible to establish stoichiometry of the coordination polyhedra of the complexes.     

Copper(II) coordination compounds with 8-quinolinaldehyde semicarbazone: Synthesis and structure

A series of compounds of the general formula Cu(HL)X₂ · nH₂O (compound I, X = ClO₄, n = 3; compound II, X = NO₃, n = 2; compound III, X = Cl, n = 0.5; compound IV, X = 1/2SO₄, n = 0) is isolated by the reactions of the copper(II) salts with quinolinaldehyde semicarbazone (HL). Regardless of the reactant ratio, only the compounds with a metal to ligand mole ratio of 1: 1 are formed, where the organic reactant is coordinated in the molecular form. The X-ray diffraction analyses of the [Cu(HL)(NO₃)(H₂O)](NO₃) · H₂O (II) and [Cu(HL)Cl₂] · 0.5H₂O(III) compounds show their substantially different organizations of the molecular structures depending on the specifics of the acido ligand. An ionic structure with one NO ₃ ^? anion incorporated into the inner coordination sphere of the metal as a bidentate chelate ligand is observed in compound II. Molecular tetragonal pyramidal complexes associated into a dimer due to the bridging function of one coordinated Cl^? anion are formed in structure III. The coordination polyhedron of the copper atom in structures II and III is an asymmetrically extended tetragonal bipyramid. The CuClCu angle equal to 90° and the distance between two planes in compound III equal to 2.978 Å determine the insignificant antiferromagnetic interaction in this compound (g = 2.1, J = ?2.5 cm^?1).     

Transition Metal Complexes with Thiosemicarbazide-Based Ligands. Part 37.* Synthesis and Study of the first Thiosemi-Carbazide-Derived Copper(I) Complexes: Crystal Structure of [2-(Diphenylphosphino)Benzaldehyde Thiosemicarbazonato(−1)] Copper(I)-Nitrate-Methanol Solvate

Abstract

The preparation and physical characterization of two copper(I) complexes Cu(HL)NO₃ and [Cu(HL)₂]NO₃·MeOh formed with a newly synthesized tridentate [S,N,P] HL = 2-(diphenylphosphino)benzaldehyde thiosemicarbazone ligand and the crystal structure analysis of the latter have been carried out. An X-ray study of [Cu(HL)₂]NO₃·MeOH revealed a copper(I) ion coordinated tetrahedrally to S,N,P,P atoms donated by two HL ligands. One is tridentate [S,N,P], whereas the second HL ligand is monodentate, ligating only its phosphorus atom to the copper. The geometry around the four-coordinate Cu(I) is comparable with Cu{N,S,P,X} tetrahedra (X = N, P, or S) retrieved from the Cambridge Structural Database. In addition, with a restriction to Cu{N,P,X,X} (X = C,N,P) tetrahedra ‐ S is excluded ‐ ca. 60 structures against     

四个对苯酚四唑硫酮金属(II)配合物的合成和晶体结构

四唑酸(–CN4H)与羧酸(–COOH)具有相似的酸性。对苯酚四唑硫酮(H2L)可以作为单齿(–S或–N)或双齿(–N, N或–N, S)配体与金属离子配位形成配位化合物。合成了4个以H2L为配体的金属(II)配合物：Co(HL)2(Py)2(H2O)2 (1), [Mn(HL)2(H2O)4]·2H2O (2), Mn(HL)2(Phen)2 (3), and [Zn(HL)2(Phen)2]·0.5H2O·1.5CH3OH (4),并用X−射线单晶衍射法测定了晶体结构。晶体结构分析表明,在这些配合物中所有的中心金属原子均呈现六配位的八面体构型。在配合物1和2中,HL–配体以氧原子与中心金属原子配位,而在配合物3和4中HL–配体则以硫原子与中心金属原子配位。     

Ion‐Directed Coordinative Polymerization of Copper(II) Pyridyl‐Alcohol Complexes Through Thiane Functionalities

A mononuclear complex [Cu(HL · S)₂(NO₃)₂] ( 1 ) and a one‐ dimensional coordination polymer [Cu(HL · S)Cl₂]_n ( 2 ) [HL · S = 4‐(pyridin‐2‐ylmethyl)tetrahydro‐2H‐thiopyran‐4‐ol] showcase the structure‐directing role of the counterions in their formation reaction: monodentate ligation of NO₃^– and Cl^– induces an octahedral (with two HL · S per Cu in 1 ) or trigonal‐bipyramidal (with one HL · S per Cu in 2 ) Cu^II coordination environment. In contrast to 1 exhibiting no coordinative metal–sulfur bonds in the crystal lattice (space group P2₁/c), 2 (P2₁/c) features intermolecular Cu–S contacts of 2.3188(7) Å. The coordination compounds are thermally stable up to ca. 160 °C. Whereas 1 demonstrates the spin‐like behavior of an isolated central Cu^II ion, compound 2 exhibits weak antiferromagnetic intra‐chain coupling with J ≈ –2.1 cm^–1 between neighboring Cu^II ions.     

Novel 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone and Zn(II), Cu(II), Ni(II) and Co(III) complexes: Synthesis,characterization, crystal structure,antioxidant, antimicrobial and antiproliferative activity

New zinc (II), copper (II), nickel (II) and cobalt (III) complexes, [Zn (HL)₂]I₂ (1) , [Cu (HL)Cl₂] (2) , [Cu (HL)Br₂] (3) , [Cu (HL)(H₂O)₂](ClO₄)₂ (4) , [Ni (HL)₂]I₂·H₂O (5) , [Co(L)₂]Cl (6) , [Co(L)₂]NO₃ (7) , [Co(L)₂]I·[Co(L)₂](I₃) (8) were obtained with 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone ( HL ). The isothiosemicarbazone ligand was characterized by NMR (¹H and ¹³C), IR spectroscopy and X-ray diffraction. All the complexes were characterized by elemental analysis, IR, UV–Vis, ESI-MS spectroscopy, molar conductivity, magnetic susceptibility measurements. X-ray diffraction analysis on the monocrystal and powder elucidated the structure of the complexes 1 , 5 , 7 and 8 . The ligand and the complexes were tested for their antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans. Also, the antiproliferative properties of these compounds on human leukemia HL-60, human cervical epithelial HeLa, human epithelial pancreatic adenocarcinoma BxPC-3, human muscle rhabdomyosarcoma spindle, large multinucleated RD cells and normal MDCK cells have been investigated. The nickel complex 5 and cobalt complexes 6 , 7 showed promising antiproliferative activity and low toxicity.     

Synthesis,X-ray crystal structure and magnetic study of a μ 1,5-dca bridged ferromagnetic dimeric copper(II) complex

Reaction of Cu(NO₃)₂ · 3H₂O, 1-(N-salicyalideneimine)-2-(N,N-dimethyl)-aminoethane (HL¹), LiClO₄, and sodium dicyanamide (Nadca) in aqueous medium affords a dimeric complex [Cu₂(L¹)₂ (μ_{1, 5}-dca)](ClO₄) (1). Single crystal X-ray analysis reveals that 1 is dinuclear with copper(II) ions bridged by a single dicyanamide group in end-to-end fashion. The coordination environment around copper(II) is square planar. Two nitrogens and oxygen of the tridentate Schiff-base ligand (HL¹) occupy three coordination sites of the square plane while the remaining site is occupied by the nitrogen of a terminal nitrile of the bridging dca. The nitrogen of the other terminal nitrile group of the μ_1,5-dca ligand connects a neighboring [CuL¹] unit to yield [Cu₂(L¹)₂(μ_1,5-dca)](ClO₄) (1). Variable temperature magnetic susceptibility measurements show that the magnetic interaction is ferromagnetic (J = 1.93 cm^?1). The results of a magnetic model are in good agreement with the experimental data.     

Two two‐dimensional supramolecular copper(II) and cobalt(III) complexes derived from a new quinazoline‐type ligand: Syntheses,structures, and spectral,thermal, electrochemical and antimicrobial activity studies

Two two‐dimensional supramolecular copper(II) and cobalt(III) complexes, Cu(L¹)₂ ( 1 ; HL¹ = 2‐hydroxy‐3‐methoxybenzaldehyde oxime) and [Co(L²)₂]₂⋅2CH₃COOCH₂CH₃ ( 2 ; HL² = 1‐(2‐{[(E )‐3‐methoxy‐2‐hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Cu(II) nitrate trihydrate and Co(II) acetate tetrahydrate with HL. A plausible reaction mechanism for the formation of HL¹ is proposed. HL was synthesized and characterized using infrared, ¹H NMR and ¹³C NMR spectra, as well as elemental analysis. Complexes 1 and 2 were investigated using single‐crystal X‐ray diffraction and have a 2:1 ligand‐to‐metal ratio. Different geometric features of both complexes are observed. In their crystal structures, 1 and 2 form infinite two‐dimensional structures and 2 forms a three‐dimensional supramolecular framework. Electron paramagnetic resonance spectra of 1 and 2 were also investigated. Moreover, thermal and electrochemical properties and antimicrobial activity of 2 were also studied. In addition, the calculated HOMO and LUMO energies show the character of complex 1 .     

Coordination Polymers with Different Dimensionalities: from 2D Layer to 3D Framework

Two coordination polymers, namely [Cd(HL)₂]_n · nH₂O ( 1 ) and [Zn(L)]_n ( 2 ) (H₂L = benzimidazole‐2‐butanoic acid), were prepared by solvothermal reaction of Cd(NO₃)₂ or Zn(NO₃)₂ and H₂L. The structures of these two compounds were determined by the single‐crystal X‐ray diffraction analyses and further characterized by IR spectroscopy, elemental analyses, powder X‐ray diffraction analyses, and thermal analyses. Compound 1 is a two‐dimensional (2D) layer framework, which is further packed into a 3D supramolecular framework by intermolecular hydrogen bonds, whereas compound 2 is a three‐dimensional (3D) framework with 3‐connected etb topology. The H₂L ligand in compounds 1 and 2 displays two different anionic forms (HL^– and L^2–), which then adopt two different coordination modes. Moreover, thermal stabilities and luminescent properties of these two compounds were also investigated.     

Linking of CuI Units by Tetrahedral Mo2E2 Complexes (E=P,As)

The reaction of [Cp₂Mo₂(CO)₄(μ,η^2:2-E₂)] ( A : E=P, B : E=As, Cp=C₅H₅) with the WCA-containing Cu^I salts ([Cu(CH₃CN)₄][Al{OC(CF₃)₃}₄] (CuTEF, C ), [Cu(CH₃CN)₄][BF₄] ( D ) and [Cu(CH₃CN)_3.5][FAl{OC₆F₁₀(C₆F₅)}₃] (CuFAl, E )) affords seven unprecedented coordination compounds. Depending on the E₂ ligand complex, the counter anion of the copper salt and the stoichiometry, four dinuclear copper dimers and three trinuclear copper compounds are accessible. The latter complexes reveal first linear Cu₃ arrays linked by E₂ units (E=P, As) coordinated in an η^2:1:1 coordination mode. All compounds were characterized by X-ray crystallography, NMR and IR spectroscopy, mass spectrometry and elemental analysis. To define the nature of the Cu⋅⋅⋅Cu⋅⋅⋅Cu interactions, DFT calculations were performed.     

Synthesis,spectroscopic and the biological activity studies of thiosemicarbazones containing ferrocene and their copper(II) complexes

Two Schiff bases, 1-acetylferrocene thiosemicarbazone (HL¹) and 1,1′-diacetyl-ferrocene dithiosemicarbazone (H₂L²) and their copper(II) complexes were prepared and characterized by elemental analysis, magnetic susceptibility, conductivity, and spectral (IR, UV–Vis, ESR) measurements The IR spectra showed that HL¹ acts as neutral or monobasic bidentate ligand, coordinating to copper(II) through either thiono- or thiolo-sulphur and azomethine-N atoms, whereas H₂L² is a neutral or dibasic mononucleating or binucleating quadridentate ligand coordinating through the same atoms. Other spectral measurements indicate that complexes [(L¹)₂Cu], [(L²)Cu] and [(HL¹)₂Cu]X₂, X?=?Cl, Br or ClO₄ have square-planar geometry around copper(II) while [(HL¹)CuX₂] and [(H₂L²)Cu₂X₄], X?=?Cl or Br, have distorted tetrahedral geometry. The biological activity studies of the complexes and the free ligands towards two gram positive and two gram negative bacteria and one fungal species have been studied and the potential is related to the nature and structure of the tested compounds.     

Copper(I) and copper(II) complexes with pyrazine-containing pyridylalkylamide ligands N-(pyridin-2-ylmethyl)pyrazine-2-carboxamide and N-(2-(pyridin-2-yl)ethyl)pyrazine-2-carboxamide

Four copper(II) complexes and one copper(I) complex with pyridine-containing pyridylalkylamide ligands N-(pyridin-2-ylmethyl)pyrazine-2-carboxamide (HL^pz) and N-(2-(pyridin-2-yl)ethyl)pyrazine-2-carboxamide (HL^pz?) were synthesized and characterized. The X-ray crystal structures of [Cu₂(L^pz)₂(4,4?-bipy)(OTf)₂] (1, OTf?=?trifluoromethanesulfonate, 4,4?-bipy?=?4,4?-bipyridine) and [Cu(L^pz)(py)₂]OTf·H₂O (2, py?=?pyridine) revealed binuclear and mononuclear molecular species, respectively, while [Cu(L^pz)(μ₂-1,1-N₃)]_n (3), [Cu(L^pz?)(μ₂-1,3-N₃)]_n (4), and [Cu(HL^pz)Cl]_n (5) are coordination polymer 1-D chains in the solid state.     

Spectral,magnetic and thermal studies on homometallic and heterometallic complexes of piperanol thiosemicarbazone

Piperanol thiosemicarbazone (HL) has been interacted with Ag⁺, Co(II), Ni(II) or Cu(II) binary to produce [Ag(HL)]EtOH · NO₃, [Ag₂(L)(H₂O)₂]NO₃, [Co(L)₃], [Cu(L)(H₂O)₃(OAc)]H₂O or [Ni(L)₂] and template with Ag⁺ to form [Cu₂Ag₂(L)₂(OH)₂(H₂O)₄]NO₃ and [NiAg(L)₂(H₂O)₂]NO₃. The prepared complexes are characterized by microanalysis, thermal, magnetic and spectral (IR, ¹H NMR, ESR and electronic) studies. Ag⁺ plays an important role in the complex formation. The variation in coordination may be due to the presence of two different metal ions and the preparation conditions. The outside nitrate is investigated by IR spectra. The outer sphere solvents are detected by IR and thermal analysis. Ni(II) complexes are found diamagnetic having a square-planar geometry. Cu(II) is reduced by the ligand to Cu(I). The cobalt complex is found diamagnetic confirming an air oxidation of Co(II) to Co(III) having a low spin octahedral geometry. The ligand and its metal complexes are found reducing agents which decolorized KMnO₄ solution in 2N H₂SO₄. CoNS and NiNS are the residual parts in the thermal decomposition of [Co(L)₃] and [Ni(L)₂].     

3-乙基-2-乙酰吡嗪缩4-苯基氨基脲Ag(I)配合物的合成、结构和DNA结合性质

合成并通过单晶衍射、元素分析及红外光谱表征了配合物[Ag₂（HL）（NO₃）₂]_n（1）的结构（HL为3-乙基-2-乙酰吡嗪缩4-苯基氨基脲）。单晶衍射结果表明,配合物1中,HL作为中性四齿配体连接2个Ag（I）中心,其中一个Ag（I）中心与HL配体中的ON₂供体（羰基O,亚胺N和吡嗪N1原子）和2个单齿硝酸根配位,构成扭曲的四方锥配位构型;而另一个Ag（I）离子与1个单齿硝酸根,1个双齿硝酸根和HL配体中的吡嗪N4原子配位,形成扭曲平面正方形配位构型。另外,相邻的Ag（I）离子通过桥联的硝酸根离子相互连接形成二维层状结构;此外,配合物1与DNA的相互作用强于配体。     

Thermal properties and CT-DNA/BSA binding behavior of a binuclear Cu(II) complex with acylhydrazone containing naphthalene ring

A novel Cu(II) complex [Cu₂L₂(NO₃)₂] with 2-hydroxy-1-naphthaldehyde-(4’hydroxy)phenylacetyl hydrazone (C₁₉H₁₄N₂O₂·H₂O, HL) was synthesized. The structure of [Cu₂L₂(NO₃)₂] was characterized by X-ray single-crystal diffraction and can be described as a distorted rectangular pyramid with binuclear coordination. IR, UV–vis and EPR spectra are used to discuss the structure of Cu(II) complex in different conditions. Magnetic properties were determined by EPR spectra and magnetic susceptibility studies, showing magnetic exchange interaction and weak antiferromagnetic exchange between two Cu(II) ions. The apparent activation energy (E_a) of thermal decomposition of compounds indicated that the thermal stability of [Cu₂L₂(NO₃)₂] is better than HL. The CT-DNA binding behavior of compounds was determined by UV–vis absorption and viscosity measurements and the results confirmed an intercalative binding mode with CT-DNA. K_b obtained was 6.24(±0.12) × 10⁶ M^?1 and 3.09(±0.006) × 10⁶ M^?1 for [Cu₂L₂(NO₃)₂] and HL, respectively, revealing that the binding ability of [Cu₂L₂(NO₃)₂] with CT-DNA was stronger. The thermogenic curves of compounds interacting with CT-DNA were monitored by microcalorimetry, showing they were all endothermic reactions with reaction within 27–42 min; interaction enthalpies (ΔH) of [Cu₂L₂(NO₃)₂] and HL were 30.3 and 4.31 kJ mol^?1. Binding studies with BSA were evaluated by fluorescence spectroscopy and the same relative interactions were found comparing with the above CT-DNA experiments.     

Synthesis,structural studies,and antibacterial activity of zinc,copper, and silver complexes derived from N′-(1-(pyrazin-2-yl)ethylidene)isonicotinohydrazide

The multidentate Schiff-base ligand N′-(1-(pyrazin-2-yl)ethylidene)isonicotinohydrazide (HL) has been prepared. Reaction with zinc, copper, and silver nitrate afford three complexes, [Zn(HL′)₂](NO₃)₂·3H₂O (1), {[Cu₂(L)₂(NO₃)(H₂O)₂]·NO₃}_n (2) and {[Ag₂(L)₂]·3H₂O}_n (3). These complexes have been characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. In 1, HL is a neutral tridentate ligand, whereas in 2 and 3, HL is a deprotonated tetradentate ligand. The hydrogen bonding interactions between NO₃^? and the host framework result in various supramolecular polymeric structures: a 2-D layer for 1 and 3-D network for 2 and 3. The antibacterial activities of these complexes have been investigated and the results indicate that 3 showed good antibacterial activities.     

Synthesis,Structure, and Properties of Nickel(II) and Cobalt(II) Coordination Compounds with Optically Active Diaminodioxime (H2L) Derived from 3-Carene. Molecular and Crystal Structures of the [Ni(H2L)(NO3)]NO3 and [Ni(HL)]ClO4 · H2O Complexes

Nickel(II) and cobalt(II) complexes with optically active diaminodioxime (H₂L, the derivative of 3-carene) of the compositions [Ni(H₂L)NO₃]NO₃ (I), Ni(H₂L)Cl₂ (II), [Ni(HL)]ClO₄ · H₂O (III), and Co(H₂L)Cl₂ (IV), were synthesized. According to X-ray diffraction data, the structures of the paramagnetic compound I and diamagnetic complex III are ionic. In the cation of I, the distorted NiN₄O₂ octahedron is formed by the N atoms of the tetradentate cyclic ligand (H₂L molecule) and by the O atoms of NO₃ ^–; anion functioning as bidentate cyclic ligands. In the cation of III, the NiN₄ coordination unit is a distorted square formed upon coordination of the tetradentate cyclic ligand, HL^–; anion. The data of magnetochemistry and UV-Vis, IR, and Raman spectroscopy suggest that paramagnetic complexes II and IV contain a distorted octahedral polyhedron MCl₂N₄ (M = Ni, Co).     

Complexes derived from the general copper(II)/maleamic acid/N,N′,N′′-chelate reaction systems: Synthetic,reactivity, structural and spectroscopic studies

The synthetic investigation of the Cu^II/maleamate(−1) ion (HL⁻)/N,N′,N′′-chelate general reaction system has allowed access to compounds [Cu₂(HL)₂(bppy)₂](ClO₄)₂·H₂O (1·H₂O), [Cu(HL)(bppy)(ClO₄)] (2) and [Cu(HL)(terpy)(H₂O)](ClO₄) (4) (bppy = 2,6-bis(pyrazol-1-yl)pyridine, terpy = 2,2′;6′,2′′-terpyridine). In the absence of externally added hydroxides, compound [Cu₂(L′)₂(bppy)₂](ClO₄)₂ (3) was obtained from MeOH solutions; L′⁻ is the monomethyl maleate(−1) ligand which is formed in situ via the Cu^II-assisted HL⁻ → L′⁻ transformation. In the case of tptz-containing (tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) reaction systems, the Cu^II-assisted hydrolysis of tptz to pyridine-2-carboxamide (L1) afforded complex [Cu(L1)₂(NO₃)₂] (5). The crystal structures of 1–5 are stabilized by intermolecular hydrogen bonding and π–π stacking interactions. Characteristic IR bands of the complexes are discussed in terms of the known structures and the coordination modes of the ligands.