Structure and magnetic properties of the copper(II) complexes with diacyl hydrazides of salicylic acid

The structures and results of the static magnetic susceptibility investigation of the copper(II) binuclear complex with salicylic acid diacyl hydrazide (H₂L), [Cu₂(L)(Py)₄] (I), and the copper(II) trinuclear complex with diacyl dihydrazide of salicylic and glutaric acids (H₆L′), [Cu₃(L′)(Py)₄] · 2Py (II), are described. The exchange antiferromagnetic interactions between the paramagnetic centers with the exchange interaction parameter −2J = 119 cm⁻¹ for dimer I and 14 cm⁻¹ for trinuclear complex II are detected.     

Structure and magnetic properties of a novel heterospin 1-D chain complex containing both Cu(II) and nitroxide radicals as spin branches

A novel heterospin one-dimensional (1-D) chain complex containing both Cu(II) and nitroxide radical ligands, {[Cu(tcph)(H₂O)₄][Cu(tcph)(NIT3Py)₂]·2H₂O} _n (1) (H₂tcph = tetrachloro-phthalic acid, NIT3Py = 2-(3′-pyridyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide), has been synthesized and structurally characterized. The structure consists of neutral chains of copper(II) ions bridged by tcph and coordinated alternatively by nitroxide radicals as spin branches and solvated water as co-ligand. The magnetic data were fitted using an approximate theoretical model based on population analysis to obtain the coupling parameter values of J _Cu2-Rad = 22.4 cm⁻¹ and J′_Cu1-Cu2 = −2.4 cm⁻¹, indicating the intramolecular ferromagnetic interaction between Cu(II) and NIT3Py and weak antiferromagnetic interaction between Cu1 and Cu2 linked by tcph.     

Synthesis and structural characterization of a novel tetranuclear Cu(II) complex: [Cu<Subscript>4</Subscript>L<Subscript>2</Subscript>(pic)<Subscript>4</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>]·2H<Subscript>2</Subscript>O

A novel Salen-type bisoxime ligand, 6,6′-dimethoxy-2,2′-[(1,4-butylene)dioxybis(nitrilomethylidyne)]diphenol (H₂L) and its tetranuclear Cu(II) complex, [Cu₄L₂(pic)₄(H₂O)₂]·2H₂O, have been synthesized and characterized by elemental analyses, IR, TG-DTA and ¹H-NMR etc. The X-ray crystal structure of the complex reveals that formation of a tetranuclear structure, which consists of four copper(II) atoms, two pentadentate L²⁻units, four picratols, two coordinated water molecules and two crystallizing water molecules. Around four copper ions are all octahedral geometries. It was demonstrated that the picratols in the tetranuclear copper(II) complex show a novel tridentate coordination mode.     

Synthesis,characterization and structures of copper(II) complexes with amide-based ligands: Unusual formation of a linear trimer and a zig-zag chain and their contrast magnetic behaviour

The present work illustrates the versatile coordination modes of the amide-based ligands towards copper(II) ion. The reaction of the deprotonated form of the ligand, [L¹]²⁻ with CuCl₂ affords a linear trinuclear complex, [Cu₃(L¹)₂(Cl)₂(H₂O)] (1) which has been characterized thoroughly including single crystal structure analysis. The structure of 1 shows that one of the arm of the flexible ligand flips to coordinate second copper(II) centre, resulting in the formation of a trinuclear complex. On the other hand, ligand H₂L² in its deprotonated form reacts with Cu(II) ion to give complex 2 with general formula, [Cu(L²)]_n (2). The crystal structure of the complex 2 shows that each copper is square-pyramidal with 5th coordination coming from the O-atom of the amide group from a neighbouring complex. This results in the generation of an one-dimensional zig-zag chain. The variable temperature magnetic measurements of the complexes, 1 and 2 show that while Cu ions in the former are antiferromagnetically coupled (J = −110.34 cm⁻¹), a weak ferromagnetic interaction (J = +3.08 cm⁻¹) exists in the later. A rationale, based on the orbital overlap from the copper ions and associated ligands, is provided for the observed magnetic coupling between the copper ions.     

Self-assembly of porous two-dimensional copper(II) α, β-unsaturated carboxylate complexes with trimethyl phosphate

A new type of two-dimensional network was found in the hydrogen-bonded molecular assemblies of copper(II) α,β-unsaturated carboxylate complexes with TMP [OP(OMe)₃], {Cu₂A₄(H₂O)₂[OP(OMe)₃]} _n [(1) A = CH₂=CHCO₂ ⁻; (2) A = CH₂=C(Me)CO₂ ⁻]. The crystal structure of (1) has been determined by single-crystal X-ray diffraction. Both complexes are unique in terms of a sheet structure brought about by O—H ⋯ O hydrogen-bonded interactions both between neighbouring Cu₂A₄(H₂O)₂ units and between Cu₂A₄(H₂O)₂ and OP(OMe)₃ molecules. The electronic reflectance spectra in the solid state suggest a square pyramidal coordination environment around the copper(II) atom. Room temperature X-band e.s.r. spectra of powered samples and variable-temperature magnetic susceptibility studies indicate the presence of strong antiferromagnetic exchange interactions between two copper(II) atoms, with 2J = −310 cm⁻¹ for (1) and 2J = −304 cm⁻¹ for (2) respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis and Magnetism of Copper(II)-lanthanide(III)-copper(II) Heterotrinuclear Complexes with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-bis [2-(dimethylamino)ethyl]oxamidocopper(II)

Nine new μ-oxamido-bridged copper(II)-lanthanide(III)-copper(II) heterotrinuclear complexes described by the overall formula Cu₂(dmoxae)₂Ln(NO₃)₃ {Ln = Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er; dmoxae = N,N′-bis[2-(dimethylamino)ethyl]oxamido dianions} have been synthesized by the strategy of ‘complex as ligand’, and characterized by elemental analyses, molar conductivity measurements, i.r. and electronic spectral studies. The variable-temperature susceptibility (2–300 K), e.s.r. measurements, and studies of the Cu₂(dmoxae)₂Gd(NO₃)₃ complex have revealed that the central gadolinium(III) and terminal copper(II) ions are ferromagnetically coupled with the exchange integral J_(Cu-Gd) = +2.1 cm⁻¹, while an antiferromagnetic coupling is detected between the terminal copper(II) ions with J′_(Cu-Cu)=−0.36 cm⁻¹, on the basis of the spin Hamiltonian operator . A plausible mechanism for the ferromagnetic coupling between copper(II) and gadolinium(III) is discussed in terms of spin polarization.     

Synthesis,crystal structure and magnetic properties of [(LCu)(MeOH)Cu(phen)-(MeOH)]ClO4·NO3 (H2L = 2,3-dioxo-5,6:15,16-dibenzo-1,4,8,13-tetraazacyclo-pentadeca-7,13-diene)

A dinuclear copper(II) [(LCu)(MeOH)Cu(phen)(MeOH)]ClO₄·NO₃ macrocyclic complex (where H₂L = 2,3-dioxo-5,6:15,16-dibenzo-1,4,8,13-tetraazacyclo-pentadeca-7,13-diene; phen = 1,10-phenanthroline) has been synthesized and characterized by means of elemental analysis and its i.r. spectrum. Its crystal structure has been determined by single-crystal X-ray diffraction. In the complex, both the copper ions are penta-coordinated and have a distorted square pyramid configuration. Magnetic susceptibility measurements show antiferromagnetic exchange interactions (J = –207.64 cm^–1) between the copper(II) ions.     

Synthesis, crystal structure and magnetic properties of bimetallic complex of Ni2Co(TTHA)·12H2O

The bimetallic complex of Ni₂Co(TTHA)·12H₂O (TTHA = triethylene tetraminehexaacetic acid) was synthesized and characterized structurally and magnetically. The title complex crystallizes in the triclinic space group P ī with a = 0.7316(2), b = 0.8624(2), c = 1.5041(4) nm; α = 73.38(2), β = 83.97(2), γ = 70.50(2)°. The crystal structure is built up of [Ni₂(TTHA)(H₂O)₂]²⁻, Co(H₂O)₆²⁺ and water molecules. The variable magnetic measurement shows that there is strong antiferromagnetic interaction between two Ni(II) ions in [Ni₂(TTHA) (H₂O)₂]²⁻ with J _Ni−Ni = −141.64 cm⁻¹, g _Ni = 2.21 and that the constant of spin-orbit coupling of Co(II) ion is −134.8 cm⁻¹. __________ Translated from Acta Scientiarum Naturalium Universitatis Nankaiensis, 2007, 40(1): 6–10 [译自: 南开大学学报(自然科学版)]     

Synthesis, crystal structure and magnetism study on novel one-dimensional Cu(II) coordination polymers with 2,5-dimethylpyrazine-1,4-dioxide as bridging ligand

A novel one-dimensional coordination polymer [Cu(μ _1,6-dmpzdo)(dmpzdo)₂]·(ClO₄)₂ (dmpzdo = 2,5-dimethylpyrazine-1,4-dioxide) has been synthesized and its crystal structure determined by X-ray crystallography. In the complex each Cu1 atom is located in a square planar coordination environment with two oxygen atoms O2 and O2A from two dmpzdo terminal ligands, and two other oxygen atoms O3 and O3A from two μ _1,6-dmpzdo bridging ligands. The one-dimensional chain is constructed by the coordination of a μ _1,6-dmpzdo bridging ligand and Cu(II) ions. The data of the variable temperature (4–300 K) magnetic susceptibilities were fitted by using the one-dimensional chain fitting formula, which gave the magnetic coupling constants 2J = −98.88 cm⁻¹.     

五-和六配位的三核锌配合物{[ZnL(OAc)]2Zn}∙CH3COCH3的合成，晶体结构及荧光性质

合成并结构表征了一种新型的线性三核锌(II)配合物,{[ZnL(OAc)]2Zn}∙CH3COCH3（H2L：乙二氧双(5-溴-2-羟基苯亚甲基胺)）。X-射线结构表明配合物中三个锌(II)离子配位到了两个四齿的L2-单元和两个桥联的的乙酸根基团。围绕两端的Zn(1) 或 Zn(1)#1原子形成了扭曲的四方锥配位几何体,围绕中心Zn(2) 原子构成了一个稍微扭曲的八面体配位结构。同时,观察到锌(II)配合物能发出蓝绿色荧光,其最大发射波长为464 nm。     

Models for the active site in galactose oxidase: Structure, spectra and redox of copper(II) complexes of certain phenolate ligands

Galactose oxidase (GOase) is a fungal enzyme which is unusual among metalloenzymes in appearing to catalyse the two electron oxidation of primary alcohols to aldehydes and H₂O₂. The crystal structure of the enzyme reveals that the coordination geometry of mononuclear copper(II) ion is square pyramidal, with two histidine imidazoles, a tyrosinate, and either H₂O (pH 7.0) or acetate (from buffer,pH 4-5) in the equatorial sites and a tyrosinate ligand weakly bound in the axial position. This paper summarizes the results of our studies on the structure, spectral and redox properties of certain novel models for the active site of the inactive form of GOase. The monophenolato Cu(II) complexes of the type [Cu(L1)X][H(L1) = 2-(bis(pyrid-2-ylmethyl)aminomethyl)-4-nitrophenol and X⁻ = Cl⁻ 1, NCS⁻ 2, CH₃COO⁻ 3, ClO₄ ⁻ 4] reveal a distorted square pyramidal geometry around Cu(II) with an unusual axial coordination of phenolate moiety. The coordination geometry of 3 is reminiscent of the active site of GOase with an axial phenolate and equatorial CH₃COO⁻ ligands. All the present complexes exhibit several electronic and EPR spectral features which are also similar to the enzyme. Further, to establish the structural and spectroscopic consequences of the coordination of two tyrosinates in GOase enzyme, we studied the monomeric copper(II) complexes containing two phenolates and imidazole/pyridine donors as closer structural models for GOase. N,N-dimethylethylenediamine and N,N’-dimethylethylenediamine have been used as starting materials to obtain a variety of 2,4-disubstituted phenolate ligands. The X-ray crystal structures of the complexes [Cu(L5)(py)], (8) [H₂(L5) = N,N-dimethyl-N’,N’-bis(2-hydroxy-4-nitrobenzyl) ethylenediamine, py = pyridine] and [Cu(L8)(H₂O)] (11), [H₂(L8) = N,N’-dimethyl-N,N’-bis(2-hydroxy-4-nitrobenzyl)ethylenediamine] reveal distorted square pyramidal geometries around Cu(II) with the axial tertiary amine nitrogen and water coordination respectively. Interestingly, for the latter complex there are two different molecules present in the same unit cell containing the methyl groups of the ethylenediamine fragmentcis to each other in one molecule andtrans to each other in the other. The ligand field and EPR spectra of the model complexes reveal square-based geometries even in solution. The electrochemical and chemical means of generating novel radical species of the model complexes, analogous to the active form of the enzyme is presently under investigation.     

Synthesis,crystal structures and magnetic properties of a radical ligand and its corresponding copper(II) complex

A new chelating radical ligand, IMMeBzIm (IMMeBzIm = 2-{2′-[(l′-methyl)benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl) and its copper(II) complex [Cu(IMMeBzIm)₂(ClO₄)]·(ClO₄) have been prepared and characterized by IR, magnetic and single-crystal X-ray analysis. In the crystal structures, both free IMMeBzIm and the complex crystallize in monoclinic space groups P2(1)/c and C2/c, respectively. The structure of IMMeBzIm consists of mononuclear molecules. In the complex, the coordination geometry around copper is a distorted square pyramid, and the apical position is occupied by one oxygen atom of ClO₄ ⁻ anion. A 1-D polymer is formed through intermolecular H-bond interactions. The variable-temperature magnetic susceptibility of the free IMMeBzIm suggests weak antiferromagnetic coupling with J = −1.12 cm⁻¹ where the spin Hamitonian is defined as Ĥ = −2 JŜ ₁ Ŝ ₂ between radical and radical.     

Magnetic study of a cyano-bridged bimetallic complex with Cu<Superscript>2+</Superscript> macrocycle and [Fe(CN)<Subscript>6</Subscript>]<Superscript>3−</Superscript> ions as building blocks

A new bimetallic cyano-bridged complex, based on copper(II) macrocycle and hexacyanoiron(III) as building blocks, [CuL(H₂O)₂]{[CuL][Fe(CN)₆] · 2H₂O} (1) (L = 1,3,6,8,11,14-hexaazatricyclo[12.2.1.18,11]-octadecane) has been synthesized and magnetically characterized. Make a study of magnetic using a chain model which takes into account of monomeric impurity confirm showing an antiferromagnetic coupling in paramagnetic ions with J = −0.170 cm⁻¹ and 3.56 % impurity.     

A Binuclear Copper(II) Complex with Two Symmetric End-on Azido Bridges. Synthesis, Spectroscopy, Crystal Structure and Magnetism

A binuclear copper(II) complex with two symmetric end-on azido bridges: [Cu₂(tacn)₂(μ-N₃)₂](ClO₄)² · CH₃OH (1), where tacn = 1,4,7-triazacyclononane, has been synthesized and structurally as well as magnetically characterized. Compound (1) has the discrete binuclear structure, bridged by two end-on N₃⁻ anions. The macrocyclic ligand tacn functions as a terminal ligand. The magnetic data of compound (1) were analyzed by means of Ĥ = −2JŜ₁Ŝ₂ − DŜ_z, leading to J = 2.49 cm⁻¹, g = 2.08, D = ±0.97 cm⁻¹, zJ′ = −0.47 cm⁻¹. The ferromagnetic interaction is discussed on the basis of the structural features and is compared with the model structure of Ruiz.     

Synthesis, Crystal Structure, Photophysical Properties, and DFT Calculations of a Bis(tetrathia-calix[4]arene) Tetracadmium Complex

Abstract  

Thiacalix[4]arenes are a unique family of polydentate ligands that offer a combination of four soft sulfur atoms together with four hard phenol oxygen atoms for binding to metal ions. In this study, the tetranuclear cadmium (II) complex Cd₄^II(tca)₂·1.5CH₂Cl₂ (tca⁴⁻ = tetra-anionic p-tert-butylthiacalix[4]arene) (1) was synthesized by reaction of a deprotonated p-tert-butylthiacalix[4]arene and various Cd^II salts. The structure of 1 was established by single crystal X-ray diffraction analysis. The neutral complex 1 contains a square arrangement of four cadmium (II) ions sandwiched between two tca⁴⁻ ligands that have a ‘cone’ conformation similar to that of the free ligand. The absorption and emission properties of the free ligand H₄tca and complex 1 have been recorded and explained by DFT calculations of the molecular orbitals and electronic transitions between them.     

A new copper containing MALDI matrix that yields high abundances of [Peptide + Cu]+ ions

The dinuclear copper complex (α-cyano-4-hydroxycinnamic acid (CHCA) copper salt (CHCA)₄Cu₂), synthesized by reacting CHCA with copper oxide (CuO), yields increased abundances of [M + xCu − (x−1)H]⁺ (x = 1–6) ions when used as a matrix for matrix-assisted laser desorption ionization (355 nm Nd:YAG laser). The yield of [M + xCu − (x−1)H]⁺ (x = 1∼6) ion is much greater than that obtained by mixing peptides with copper salts or directly depositing peptides onto oxidized copper surfaces. The increased ion yields for [M + xCu − (x−1)H]⁺ facilitate studies of biologically important copper binding peptides. For example, using this matrix we have investigated site-specific copper binding of several peptides using fragmentation chemistry of [M + Cu]⁺ and [M + 2Cu − H]⁺ ions. The fragmentation studies reveal interesting insight on Cu binding preferences for basic amino acids. Most notable is the fact that the binding of a single Cu⁺ ion and two Cu⁺ ions are quite different, and these differences are explained in terms of intramolecular interactions of the peptide-Cu ionic complex.     

Synthesis and characterization of a new octamolybdate (NH4)4[Mo8O24(C3H2O2)2] · 4H2O

A new complex with the formula (NH₄)₄[Mo₈O₂₄(C₃H₂O₂)₂] · 4H₂O (1) has been synthesized and characterized by single crystal X-ray diffraction and infrared spectrum. The complex is small yellow crystal and space group P ₁ with a = 9.9869(18) ?, b = 10.030(19) ?, c = 10.366(19) ?, α = 91.68(3)°, β = 98.94(3)°, γ = 119.37(2)°, V = 887(3) ?³, and Z = 1. The complex contains two malonic acid ligands bonded to the γ-Mo_{8 26}⁴⁻ ions which consist of eight MoO₆ edge-sharing octahedral. In this crystal structure, the octamolybdate anion is mutually hydrogen bonded by ammonium ions and water molecules.     

Synthesis,crystal structure,magnetic and spectroscopic properties of {[Cu(oxbe)(py)]2Ni(py)2}·2Dmf complex of dissymmetrical oxamidate

The trinuclear complex {[Cu(oxbe)(py)]₂Ni(py)₂}·2DMF has been prepared and characterized by elemental analysis, IR and electronic spectra and magnetic susceptibility, where H₃oxbe is the dissymmetrical ligand N-benzoato-N′-(2-aminoethyl) oxamido, py?=?pyridine, DMF?=?dimethylformamide. The molecular structure of this complex is centrosymmetrical and has an extended oxamido-bridged structure consisting of two pyramidal copper(II) and one octahedral nickel(II) ions. The central Ni(II) and two terminal Cu(II) ions are antiferromagnetically coupled, J?=???60.2?cm^?1.     

Zinc citrate with alkali metal and ammonium cations: Crystal structure of K4[Zn(Citrate)2]

In the crystal of K₄[Zn(Citrate)₂], two citrate anions coordinate Zn(II) cation with octahedral geometry in the [Zn(Citrate)₂]⁴⁻ complex anion, and the charge is balanced by four potassium ions. Crystal data: monoclinic, P2₁/c, a = 8.502(2) ?, b = 13.210(3) ?, c = 8.942(2) ?, β = 113.132(4)°, V = 923.5(4) ?³, Z = 2, R = 0.0229.     

The directed synthesis and the spectral and magnetic characteristics of a new multispin (S=7/2,T=292 K) trinuclear complex

The new trinuclear complex K{(CoTp^t-Bu)[Fe(CN)₆](CoTp^t-Bu)}, in which the initial structural fragments are linked by CN⁻ bridges, was synthesized by the directed stitching of mononuclear complexes, one of which was [Fe(CN)₆]³⁻ while the other was cobalt(II) tris(3-tert-butyl-l-pyrazolyl)borate ([(CoTp^t-Bu)]⁺). The magnetic moment of K{(CoTp^t-Bu)[Fe(CN)₆](CoTp^t-Bu)} at 292 K was 8.07 μ_β (S=7/2), indicating the absence of antiferromagnetic exchange interactions in the trinuclear complex. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 6, pp. 351–354, November–December, 1998.