Thermochromic and Magnetic Properties of a Copper(Ⅱ) Coordination Compound

Copper complexes that can experience reversible heat-induced dehydration and rehydration in the solid state were rarely reported although thermochromic copper complexes have been widely reported, and their heat-induced magnetic properties have not been studied. We firstly observed the reversible thermochromic phenomena of the known copper(II) complex [Cu(bpy)(OOCCH_3)_2]n·xn H_2O(x = 2.5 or 3; bpy = 4,4?-bipyridine) in the solid state, which is associated with the dehydration and rehydration processes, and found that heat-induced coloration clearly enhanced the magnetic susceptibility.     

Structure and Magnetic Properties of a Bipyridine-bridged One-dimensional Ni(Ⅱ) Coordination Polymer

A polymer, [NiL(bipy)·2H2O]n(1, bipy = 4,4ˊ-bipyridine), has been acquired by the reaction of Ni(OAc)2·4H2O with N,Nˊ-bis(2-hydroxyl-5-fluorobenzyl)-2-hydrxylpropane dii- mine in the presence of 4,4ˊ-bipyridine. X-ray crystallographic analysis shows that it is comprised of a mononuclear Ni(Ⅱ) complex [NiL] linked by 4,4ˊ-bipyridine. Its crystal crystallizes in the orthorhombic system, space group C2/c with a = 22.595(3), b = 18.395(2), c = 15.434(2) , V = 6155(1)3, Dc = 1.259 g/cm-3, Z = 8, Mr = 583.23, F(000) = 2416.0, μ(MoKa) = 0.681 mm-1, S = 1.049, R = 0.0512 and wR = 0.1108 for 6032 observed reflections(I 2σ(I)). There are water hexamers in the complex. A weak overall ferromagnetic behavior has been evaluated by Curie-Weiss rule and by the formula of alternating ferro-ferromagnetic coupling in one-dimensional Ni(Ⅱ) chain, which gives g = 2.005(1) and J1 = 0.31(3) cm-1.     

Syntheses,Crystal Structures,and Magnetic Properties of Two Manganese(Ⅱ) Coordination Polymers Based on Bifunctional Pyridine-benzene Carboxylic Acids

Two manganese(II) coordination polymers, namely, {[Mn(PIP)(BIBP)]·(BIBP)0.5}n(1) and {[Mn(PTA)(BIMBP)(H_2O)]·H_2O_(0.69)}_n(2)(H_2PIP = 5-(4-pyridyl)-isophthalic acid, H_2 PTA =6-(4-pyridyl)-terephthalic acid, BIBP = 4,4?-bis(imidazol-1-yl)biphenyl, and BIMBP =4,4?-bis(imidazol-1-ylmethyl)biphenyl), have been synthesized by using the bifunctional pyrinde-benzene carboxylic acids and bis(imidazole) linkers as mixed ligands to react with Mn SO4,and further characterized by elemental analysis, IR, and PXRD. Compound 1 is in the triclicnic system, space group P1 with a = 10.1089(8), b = 13.1927(12), c = 14.0638(12) ?, α = 69.437(2), β= 73.2890(10), γ = 78.5320(10)o, V = 1671.9(2) ?~3, Z = 2, Dc = 1.449 g/cm3, F(000) = 705,μ(MoK α) = 0.453 mm-1, S = 1.053, R = 0.0491 and wR = 0.1367 for 5837 unique reflections(Rint =0.0208) with I 2σ(I). Compound 2 belongs to the monoclicnic system, space group C2/c with a =15.199(3), b = 19.731(3), c = 21.537(5) ?, β = 105.228(3)o, V = 6232(2) ?3, Z = 8, Dc = 1.363g/cm3, F(000) = 2648, μ(MoK α) = 0.475 mm-1, S = 1.048, R = 0.0489 and wR = 0.1151 for 7414 unique reflections(Rint = 0.0425) with I 2σ(I). Structural analyses reveal that complex 1 is a4-connected(44.62)-sql bilayer structure with binuclear [Mn_2(COO)_2] SBU, while complex 2 is a normally(3,5)-connected(42.67.8)(42.6)-3,5L2 monolayer. And the sheets interacted with the adjacent sheets through weak interactions, finally giving a stable three-dimensional(3D)supramolecule. Besides, the variable-temperature magnetic susceptibility measurement of complex1 was investigated.     

Electrophysical Properties of Coordination Compounds Based on Cobalt(II) and Manganese(II) Chlorides and ε-Caprolactam

The metal complex systems based on Co(II) and Mn(II) chlorides and -caprolactam were studied. Temperatures of the phase transition, activation energy of the electrical conductivity, and mobility of the charge carriers in the compounds obtained were determined.     

Binuclear Cu(II) and Ni(II) Complexes with Schiff Bases—the Products of Condensation of Amino Alcohols with 2-Phenylhydrazone 1-Phenylbutane-1,2,3-Trione: Synthesis and Magnetic Properties

The binuclear complexes of Cu²⁺ and Ni²⁺ with a new ligand system obtained through condensation of amino alcohols with 2-phenylhydrazone 1-phenylbutane-1,2,3-trione were synthesized. The compositions and structures of ligands and complexes were determined using elemental analysis, IR and NMR spectroscopy and magnetochemistry. The nickel complexes were found to be diamagnetic; in the copper complexes, substantial antiferromagnetic exchange interaction was observed (for Cu²⁺ complexes with n = 2 and 3, 2J is equal to –396 and –393 cm^–1, respectively). The structure of the exchange fragment is discussed.     

Three Co(Ⅱ) Coordination Polymers Incorporated with a Bent Connector: Crystal Structures and Magnetic Properties

Based on the bent ligand 1 H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole(3,4?-Hbpt) with Co(Ⅱ) ions as well as a series of polycarboxylate co-ligands, three new coordination polymers were yielded, namely, {[Co(op)(3,4?-Hbpt)(H_2O)_3]?2 H_2O}n(1), [Co(cyc)(3,4′-Hbpt)(H_2O)]n(2) and [Co(pro)(3,4′-Hbpt)(H_2O)]n(3)(here, op = o-phthalic anion, cyc = 1,1-cyclobutanedicarboxylic anion, pro = propanedioic anion). In cooperation with the auxiliary polycarboxylate co-ligands, a variety of Co(Ⅱ) coordination networks, such as 1-D chain 1 and 2-D layer 2 and 3 have been assembled. The magnetic behaviors of compounds 1～3 were studied. All of them indicated the existence of interesting spin-canting behavior.     

Syntheses,Crystal Structures and Magnetic Properties of Two New Low-dimensional Manganese (Ⅱ) Coordination Compounds

Two new low-dimensional Mn(Ⅱ) coordination compounds of Mn(H_2pimdc)_2(phen)(compound 1) and [Mn(Hpimdc)(phen)]n·nH_2O(compound 2) were synthesized, where H_3pimdc is a 2-propyl-imidazole-4,5-dicarboxylic acid and phen is 1,10-phenanthroline. Both compounds were thoroughly analyzed by X-ray single-crystal diffraction, element analysis, IR spectra, PXRD and thermal analysis. X-ray single-crystal diffraction analyses indicate that the phen ligands terminate metal ions on two sides to prevent the linkage between the neighboring metal ions into a higher dimensional structure in compounds 1 and 2. Compound 1 is constructed from mononuclear molecules which form the 1D helical supramolecular chain by N–H···O hydrogen bonds. In compound 2, Hpimdc is a tetradentate bridging ligand, which binds Mn(Ⅱ) ions to generate a single-stranded right helical chain parallel to the b axis. These 1D chains are additionally coupled by H-bonds as well as π···π stacking interactions, which formed a 3D supramolecular structure. Additionally, compound 2 demonstrated temperature-dependent magnetic susceptibility and negative value of θ(equal to –9.09 K), which is indicative of weak antiferromagnetic interactions between Mn(Ⅱ) ions.     

Synthesis and Magnetic Properties of Fe(II) and Nd(III) Complexes of Poly(N-2-thiazolylacrylamide)

In recent years,the organic ferromagnets have drawn growing attention due to their characteristics of structural diversities,low density,and readily processing1-3.Design and synthesis of magnetic polymers are one of great challenges in today′s magnetic material research,and some significant achievements have been made in this field4,5.In this article,we describe the synthesis of acrylamide-type polymer with pendent thiazolyl groups(Scheme1).The as-prepared polymer exhibited better solubility …     

Hydrothermal Synthesis,Crystal Structure and Magnetic Properties of a Cobalt(II) Coordination Polymer Assembled by 4-Sulfophthalate and 4,4'-Bipyridine

1 INTRUDUCTION The rational design and synthesis of metal-direc- ted supramolecular framework have received much attention in coordination chemistry because of their potential applications in catalysis, molecular selec- tion, non-linear optics, ion exchange and microelec- tronics[1～4]. During the lastdecade, many high-di- mensional coordination complexes have been de- signed and prepared through molecular self-as- sembly process[5～10]. The construction of open metal organic framework, s…     

Synthesis, Structure and Magnetic Properties of a Diphenoxo-bridged Binuclear Copper(II) Complex

ＩｎｔｒｏｄｕｃｔｉｏｎＥｘｃｈａｎｇｅ ｃｏｕｐｌｅｄｐｏｌｙｎｕｃｌｅａｒｃｏｐｐｅｒ(ＩＩ)ｃｏｍｐｌｅｘ ｅｓａｒｅｏｆｓｐｅｃｉａｌｉｎｔｅｒｅｓｔｄｕｅｔｏｔｈｅｉｒｉｎｖｏｌｖｅｍｅｎｔｉｎｂｉｏ ｌｏｇｉｃａｌｐｒｏｃｅｓｓｅｓａｎｄｉｎｉｎｏｒｇａｎｉｃｍａｔｅｒｉａｌｓ .1,2 Ｔｈｅｉｎｔｉ ｍａｔｅｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｔｈｅｓｐｉｎｃｏｕｐｌｉｎｇａｎｄｔｈｅｍｏｌｅｃｕｌａｒｓｔｒｕｃｔｕｒｅｈａｓｆｏｓｔｅｒｅｄｔｈｅｅｍｅｒｇｅｎｃｅｏｆｍｏｌｅｃ ｕｌａｒ…     

Investigation of Spectroscopic and Thermal Properties of Poly(o‐toluidine) Doped with Polymeric Acids

Single step polymerization of poly(o‐toluidine) was carried out by using ammonium persulphate as an oxidizing agent. Formation of the conducting emeraldine salt phase of the polymer was confirmed by the UV‐visible and FT‐IR spectroscopic analysis. The elemental composition of the polymer was evaluated by using a CHNS analyzer. Thermal stability of these polymers was investigated by the thermogravimetric analysis. Among the three polymeric acids used for doping purposes, poly(acrylic acid) doped material was found to show less thermal stability compared to poly(styrene sulphonic acid) and poly(vinyl sulphonic acid) doped poly(o‐toluidine).     

Synthesis, Structure and Magnetic Properties of Two New Homotrinuclear Bis(oxamato) Copper(II) Complexes

ＩｎｔｒｏｄｕｃｔｉｏｎＭｏｌｅｃｕｌａｒｍａｇｎｅｔｉｓｍｏｆｐｏｌｙｎｕｃｌｅａｒｃｏｍｐｌｅｘｅｓｉｓｏｆｃｏｎｓｉｄｅｒａｂｌｅｉｎｔｅｒｅｓｔｆｏｒｄｅｓｉｇｎｉｎｇｎｅｗｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓａｎｄｆｏｒｉｎｖｅｓｔｉｇａｔｉｎｇｔｈｅｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｔｈｅｓｔｒｕｃｔｕｒｅａｎｄｔｈｅｒｏｌｅｏｆｔｈｅｐｏｌｙｍｅｔａｌｌｉｃａｃｔｉｖｅｓｉｔｅｓｉｎｂｉｏｌｏｇｉｃａｌｓｙｓｔｅｍｓ.1 4 Ｊｏｕｒｎａｕｘｅｔａｌ .5ｈａｖｅｒｅｃｅｎｔｌｙｐｒｏｐ…     

Synthesis and Properties of Axial Coordination Reaction of Unsymmetric Leucine Zinc(Ⅱ) Tetraphenylporphyrin with Pyrimidine

In recent years much work has been done on the syntheses and properties of axial coordination reaction of zinc tetraphenylporphyrins with nitrogenous donors in order to better understand the detailed molecuar mechanism of natural zincous enzymes. However,only a few studies have been reported in which the nitrogenous donors are bound to the amino acid metallotetraphenylporphyrins with unsymmetric structures. In this paper, a new unsymmetric leucine tetraphenylporphyrin, 5-(4-leucine butoxyphenyl)-10,15,20-triphenylporphyrin (H₂[Leu-TPP]) and its Zn(Ⅱ) complex (Zn[Leu-TPP]) are synthesized. Their structures are characterized by elemental analysis, UV, IR, fluorescense spectra. The changes of the electronic absorption spectra of axial coordination reaction of Zn[Leu-TPP] with pyrimidine in chloroform are investigated Coordination number (n) and equilibrium constant (β) of the reaction are measured by visible spectra techniques. The changes of standard molar enthalpy (Δ_rH_m^⊙) and molar entropy (Δ_rS_m^⊙) of the reaction are calculated. The obtained data are listed in table 1.     

Coordination interactions of alkyl-substituted 2,2′-dipyrrolylmethene derivatives with copper(II) aminoacid complexes

Using the method of electron spectroscopy we showed that reaction of alkyl-substituted 2,2′-dipyrrolylmethene derivatives with copper(II) aminoacid complexes led to the formation of heteroligand complexes with two chelated metallocycles forming their coordination sphere. Formation constants of the heteroligand complexes were established and their interrelations with the structure of the aminoacid residue side group were elucidated. It was found that alongside the ability to the primary solvolytic dissociation of aminoacid complex, the main effect on the formation of combined coordination sphere of the chelate is defined by the steric factor depending on the structure of substituent in the aminoacid.     

Thermal Properties of Cobalt(II) β-Iminoketonates

Russian Journal of General Chemistry - Thermogravimetry, differential scanning calorimetry, and flow methods were used to investigate thermal properties of a series of cobalt(II)...     

Mixed Ligand Complexes of 5-arylazo-8-hydroxyquinoline and α-amino Acids with Co(II), Ni(II) and Cu(II)

Ten mixed ligand complexes of the type [M(X-QA)(aa)] and [Ni(X-QA)₂(Haa)(H₂O)],where X-HQA=5-arylazo-8-hydroxyquinoline derivatives, M=Co(II) orCu(II) and Haa=glycine (gly), alanine (ala) or methionine (met), have been prepared. The complexes have been characterized by elemental analysis, IR and electron spectra and thermal analysis. A tetrahedral structure has been proposed for the cobalt(II) and copper(II) complexes with bidentate coordination of amino acids. The nickel(II) complexes have been assigned an octahedral structure with the amino acids acting as monodentate ligands. The thermal behaviour of the complexes has been studied before and after γ-irradiation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis,Structure, and Magnetic Properties of Di-μ-Pyrazolatodicopper(II) Complexes of 3,5-Bis(Aminomethyl)Pyrazole

Abstract

3,5-Bis(aminomethyl)pyrazole (Hbampz) forms binuclear copper(II) complexes of the formula [Cu₂(bampz)₂X₂] (X = CI, Br). The crystal structure of [Cu₂(bampz)₂Br₂] has been determined by the X-ray method: formula = CuBrN₄C₅H₉, monoclinic, space group P2₁/n, a = 9.214(1), b = 10.078(1), c = 8.775(1) Å, β = 97.33(1)°, V = 808.1 ų. Two bampz^? molecules combine with two copper(II) ions via the pyrazolate nitrogen and aminonitrogen atoms in the side chains affording an essentially planar N₄ environment for each metal ion. The Cu-Cu separation is 3.947(5)A. The axial site of each copper is weakly coordinated by a bromide ion with a Cu-Br distance of 2.895(4) A. Cryomagnetic investigations over the temperature range 80-300 K revealed a significant antiferromagnetic interaction through the pyrazolate bridges. The exchange integrals (J) based on the Heisenberg model (H =—2J?₁.?₂) was estimated at—200.8 and—192.0 cm^?1 for [Cu₂(bampz)₂Cl₂] and [Cu₂(bampz)₂Br₂], respectively.     

Copper(II) Acetate–Mediated Cross-Coupling of Phenylboronic Acids with Aryloximes: Synthesis of O-Aryloximes

A novel method for the synthesis of O-aryloxime is described. It consisted of the coupling reaction between phenylboronic acids and aryloximes in the presence of catalytic quantities of copper(II) acetate. This reaction takes place in the presence of pyridine under a mild condition (DCE, Rt, 24–36 h) with moderate yield. It represents a good alternative to known methods for O-aryloxime synthesis.     

Synthesis, Crystal Structure and Magnetic Properties of Cobalt(II) Complex Involving Imino Nitroxide Radicals

1 INTRODUCTION The synthesis and study of transition metal com-plexes incorporating organic free radicals have arou-sed great interest in the field of molecular magne-tism[1]. Nitronyl nitroxide radicals (NITR), stable or-ganic radicals, have been widely used as molecularunits in the design and construction of magnetic ma-terials[2～5]. These radicals are especially attractivedue to that their donor atoms can assemble an exten-ded coordination geometry with changing magneticcoupling. A…     

Crystal Structures and Magnetic Properties of Cu(II) Complexes with Pyrazole‐Substituted Iminonitroxyl Radicals: New Trinuclear Heterospin Complexes

The paper describes the crystal structures and magnetic properties of complexes of copper(II) hexafluoroacetate (Cu(hfac)₂) with stable pyrazolesubstituted iminonitroxyl radicals containing the pyrazole substitutuent in the second position of the 2imidazoline cycle (L). A new group of [Cu(hfac)₂]₃(L)₂ complexes is found, in which L performs a bidentatebridge function due to the coordination of the imine N atoms of the pyrazole and imidazoline cycles. It is shown that in the solid complexes there are Cu²⁺—N = C—N—O exchange routes with highenergy ferromagnetic interactions (60–100 cm^-1).