Chemisorption of copper(II) at zinc and cadmium dialkyldithiocarbamates: EPR and X-ray diffraction studies

Chemisorption of Cu²⁺ cations at zinc and cadmium dialkyldithiocarbamates was studied. According to EPR data, in the first step, the zinc and cadmium atoms are partially replaced by copper in the starting molecular structure to form heterobinuclear and heteropolynuclear complexes. In the second step, copper replaces up to 90 to 97% of the total number of the metal atoms, yielding binuclear and polynuclear copper(II) complexes. The possibility of the existence of heterobinuclear complexes in the individual state was demonstrated with [CuCd{S₂CN(C₂H₅)₂}₄] as an example. Its molecular and crystal structures were determined from X-ray diffraction data.     

Mechanochemical synthesis in copper(II) halide/pyridine systems: single crystal X-ray diffraction and IR spectroscopic studies

Whereas complexes of divalent metal halides (X = Cl, Br, I) with/from pyridine commonly crystallise as trans-[M(py)(4)X(2)]·2py, M on a site of 222 symmetry in space group Ccca, true for CuCl(2) and CuBr(2) in particular, the copper(II) iodide adduct is of the form [Cu(py)(4)I]I·2py, Cu on a site of mm2 symmetry in space group Cmcm, and five-coordinate (square-pyramidal), the same cationic species also being found in 2[Cu(py)(4)I](I(3))·[(py)(2)Cu(μ-I)(2)Cu(py)(2)] (structurally defined). Bromide or N-thiocyanate may be substituted for the unbound iodide ion in the solvated salt, resulting in complexes which crystallize in space group Ccca, but with both anions and the metal atom disordered. In [Cu(py)(4)(I(3))(2)], a pair of long Cu···I contacts approach a square-planar Cu(py)(4) array. Assignments of the ν(CuN) and ν(CuX) (X = Br, I, SCN) bands in the far-IR spectra are made, the latter with the aid of analogous assignments for [Cu(py)(2)X(2)] (X = Cl, Br), which show a dependence of ν(CuX) on the Cu-X bond length that is very similar to that determined previously for copper(i) halide complexes. The structure of the adventitious complex [(trans-)(H(2)O)(py)(4)CuClCu(py)(4)](I(3))(3)·H(2)O is also recorded, with six- and five-coordinate copper atoms; rational synthesis provides [{Cu(py)(4)}(2)(μ-Cl)](I(3))(3)·H(2)O with one water molecule less. In [{Cu(py)(4)Cl}((∞|∞))](I(3))·3py, square pyramidal [Cu(py)(4)Cl](+) cations, assisted by Cl···Cu interactions, stack to give rise to infinite polymeric strings. Several of these compounds were prepared mechanochemically, illustrating the applicability of this method to syntheses involving redox reactions as well as to complex syntheses involving up to five components. The totality of results demonstrates that the [Cu(II)(py)(4)] entity can be stabilized in an unexpectedly diverse range of mononuclear and multinuclear complexes through the presence of lattice pyridine molecules, the bulky triiodide ion, or a combination of both.     

Thermal, X-ray diffraction and electronic spectral studies of gamma irradiated nickel(II) complexes of ethylenediamine, triethylenetetramine and o-toluidine

Thermal decomposition, X-ray diffraction and electronic spectra of nickel(II) complexes of ethylenediamine, triethylenetetramine and o-toluidine were studied before and after γ-irradiation. Irradiation enhanced thermal decomposition lowering thermal and kinetic parameters. From X-ray diffraction studies, unirradiated and irradiated complexes are found to be orthorhombic. A change in lattice parameters was observed upon irradiation. The parameters Dq, β and B^I were calculated from the UV–visible spectra of the complexes. Irradiation decreased Ligand Field Stabilisation Energies (LFSE) (Dq) and increased Racah parameter B^I and the covalency factor β of the complexes.     

Desolvaton of Zinc(II)tetra-tert-butylphthalocyanine Crystal Solvates as Probed by Thermogravimetry

Kinetic analysis of the thermal destruction of complexes of zinc(II)tetra-tert-butylphthalocyanine Zn(t-Bu)₄Pc with organic solvent molecules has been carried out. For ligands having high ionization potentials, long refluxing of solution is required for preparing biligand complexes. For molecular ligands whose ionization potentials do not exceed 9.2 eV, the composition of complexes with Zn(t-Bu)₄Pc is independent of the preparation parameters. The destruction of the Zn(t-Bu)₄Pc complexes with n-propylamine, diethylaniline, piperidine (1: 1, cold synthesis), diethylamine, morpholine, quinoline, or cyclopentanone (1: 2, hot synthesis; 1: 2, cold synthesis) obeys fist-order equations; for complexes with pyridine, 1,4-dioxane, DMF, cyclopentanone (1: 1, hot synthesis), 3-dimethylaminopropionitrile, or piperidine (1: 2, hot synthesis), destruction obeys second-order equations. The activation energies of thermal destruction for the first group of molecular complexes fall in the range from 89 to 370 kJ/mol; the rate-controlling stage is nucleation and growth. For the second group, the activation energies fall in the range from 160 to 640 kJ/mol; the rate-controlling stage is a chemical reaction.     

X-ray diffraction,spectroscopic (IR,Raman) and DSC studies of bis(betainium) p-toluenesulfonate monohydrate crystal

Bis(betainium) p-toluenesulfonate monohydrate (abbreviated as BBTSH) was studied at various temperatures by X-ray diffraction, differential scanning calorimetry and vibrational spectroscopy methods. DSC curves of BBTSH show a peak at about 349 K which corresponds to water escape from the crystal, and reveal the “cold crystallization” phenomenon. BBTSH crystallizes in the P2₁/c space group of monoclinic system. After heating above 349 K the compound dehydrates, the crystal system changes to triclinic, the monocrystalline samples become non-merohedral twins. The BBTSH crystal comprises p-toluenesulfonic anions, monoprotonated betaine dimers and water molecules. Three kinds of hydrogen bonds are present in the crystal: strong, asymmetric and almost linear OH⋯O hydrogen bond (R(O⋯O) = 2.463(2) Å), weak O_wH⋯O hydrogen bonds (R(O_w⋯O) = 2.820(2) − 2.822(2) Å) and weak CH⋯O hydrogen bonds (R(C⋯O) = 3.295(2) − 3.416(2) Å). The ν_aOHO vibration of the strongest hydrogen bond in the crystal gives rise to an intense broad absorption with numbers of transmission windows in the low wavenumber region of the infrared spectra. Coupling between νCO stretching vibrations of two COO groups of the betaine dimer was detected. The process corresponding to the loss of water is accompanied by the breakage of strong OH⋯O hydrogen bonds in betaine dimers and rearrangement inside half of the betaine dimers. This rearrangement results in formation of the new betaine dimers with OH∙∙∙O hydrogen bond of similar strength as corresponding bond in the hydrated form (BBTSH).     

Synthesis,spectral and thermal properties of macrocyclic zinc(II) complexes

The new zinc ternary complexes [Zn(cyclen)NO₃]ClO4 (I), [Zn₂(cyclen)₂(m-nic)](ClO₄)₃ (II), [Zn₂(cyclen)₂(m-pic)](ClO₄)₃ (III) (cyclen=1,4,7,10-tetraazacyclododecane; nic=nicotinic acid; pic=picolinic acid) were synthesized and their spectral and thermal properties were investigated. The compounds were characterized by elemental analysis, IR spectroscopy and TG/DTG, DTA methods. Moreover, the way of coordination of pyridinecarboxylate anions was proposed on the basis of the spectral data and consequently proved with results of X-ray structure analysis. This revised version was published online in August 2006 with corrections to the Cover Date.     

Preparations,IR spectra and crystal structures of cyano-bridged bimetallic complexes of zinc(II) and cadmium(II) with tetracyanopalladate(II)

The novel heteronuclear compounds [Zn(hydet-en)₂Pd(CN)₄] (1) and [Cd(hydet-en)₂Pd(CN)₄] (2) {hydet-en: N-(2-hydroxyethyl-ethylenediamine)} have been synthesized and characterized by elemental analyses and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. Structural analysis shows that both compounds have shown a polymeric chain, in which the Zn(II)/Pd(II) and Cd(II)/Pd(II) centres are linked by two CN groups. Both zinc and cadmium atoms are six coordinate with two trans cyanide–nitrogen and four hydet-en N atoms in a distorted octahedron arrangement; the palladium atoms in 1 and 2 are four coordinate with four cyanide-C atoms in a square planar arrangement. The chains in both compounds are connected through weak interchain hydrogen bonds, N–H?···?O, N–H?···?N and O–H?···?N, thereby forming a three-dimensional network.     

Structure of iron (II) and cobalt (II) bromide complexes in aqueous solution by X-ray diffraction analysis

Structures of bromo-metal complexes in concentrated aqueous solutions of FeBr₂ and of CoBr₂ were investigated by X-ray diffraction analysis. The complexes possess an octahedral geometry coordinating Br^– along with H₂O ligands. The frequency factors of metal-Br contacts per one atom of metal were 0.325 for the 2.7M (mol-dm^–3) and 0.747 for the 4.5M FeBr₂ solutions, and 0.280 for the 2.8M and 0.595 for the 4.3M CoBr₂ solutions. The frequency factors suggested that the tendency of metal ions to forming monobromo complexes is in the order, Fe>Co>Ni相似文献   

Thermal and spectral analyses of complexes of zinc(II)tetra-tertbutylphthalocyanine with amines

Spectral and thermochemical studies of complexes of zinc(II)tetra-tertbutylphthalocyanine (Zn(t-Bu)₄Pc) with some amines have been carried out. Spectral effects of the complex formation of the metallophthalocyanine with amines have been established. It has been found that an ability of Zn(t-Bu)₄Pc to coordinate amines depends on both their nature and conditions of preparation. Similarity of the crystal structures of biligand and monoligand of Zn(t-Bu)₄Pc complexes to individual β- and α-polymorphs of Zn(t-Bu)₄Pc, respectively is proved by IR spectroscopy and X-ray diffraction method.     

Thermal,spectral and magnetic studies on glycine complexes of cobalt(II), nickel(II) and zinc(II) with hydrazine

Hydrazinium metal glycinates [(N₂H_{5 2}M(NH₂CH₂COO)₄] and bis(hydrazine)metal glycinates, [M(NH₂CH₂COO)₂(N₂H₄)₂], whereM=Co, Ni or Zn have been prepared and characterized by chemical analyses, magnetic moments and vibrational and electronic spectra. The thermal behaviour of these compounds has been studied by thermogravimetry and differential thermal analyses. These complexes decompose with high exothermicity giving metal powder as the final residue. The X-ray powder data of each set of complexes show isomorphism among themselves.