Synthesis,Characterization, and Crystal Structure of [ReO(Me4tu)4](PF6)3 (tu = thiourea)

A new Re^V oxo complex with tetramethylthiourea, [ReO(Me₄tu)₄](PF₆)₃, has been synthesized by reduction of perrhenate with tin(II) chloride in strongly acidic solution in the presence of excess tetramethylthiourea. The complex has been characterized by elemental analysis and electronic and FTIR spectroscopy. The molecular structure of the compound was determined by X‐ray diffraction methods. The coordination polyhedron is a regular square pyramid with the substituted thiourea sulfur atoms in the equatorial positions [d(Re–S) = 2.339(3) Å] and the oxo ligand located in the summit [d(Re–O) = 1.63(2) Å]. Computational methods were employed to analyze the geometric and electronic structures of tetramethylthiourea and thiourea. Quantum mechanical studies suggest steric hindrance as the reason for the stabilization of the ReO³⁺ center instead of the Re^III one.     

Synthesis and NMR Characterization of Cobalt(III) Complexes with 1,8-diamino-3,6-dithiaoctane, 2,2-Bipyridine,and 1,10-phenanthroline

The complexes [Co(eee)(bipy)]Cl₃ and [Co(eee)(phen)]Cl₃ (eee, 1,8-diamino-3,6-dithiaoctane) were synthesized and characterized by two-dimensional NMR spectroscopy. The presence of the bidentate aromatic ligands 2,2-bipyridine and 1,10-phenanthroline caused the ¹H resonances to be spread into a wider spectral width than previously observed for [Co(eee)(NO₂)₂]Cl and [Co(eee)Cl₂]Cl. Separate multiplets were observed for the four protons in the terminal ethylene linkage. It was possible to positively assign each multiplet and to determine the relative spatial orientations of the corresponding protons.     

Synthesis and crystal structure of [ReO(ahp)2(PPh3)]Cl (Hahp=2-amino-3-hydroxypyridine): a novel cationic monooxorhenium(v) complex

The cationic complex [ReO(ahp)₂(PPh₃)]⁺ was isolated as the chloride salt from the reaction of trans-[ReOCl₃(PPh₃)₂] and 2-amino-3-hydroxypyridine (Hahp) in ethanol. Coordination of the chelates only occurs through the amino nitrogen and the phenolate oxygen of ahp^?. The X-ray crystal structure shows a distorted octahedral geometry, in which a phenolate oxygen coordinated trans to the oxo group and the rhenium atom is displaced by 0.2520(1) Å out of the mean equatorial plane towards the oxo oxygen.     

Coordination of 2,3-diaminopyridine in the diamidopyridinium mode to the ReO3+ core

2,3-Diaminopyridine (H₂dap) reacts with (n-Bu₄N)[ReOCl₄] to form an air-stable salt of composition [ReO(Hdap)₂]Cl·2H₂O. Spectroscopic studies and X-ray crystallography show that Hdap is coordinated in the monoanionic diamidopyridinium mode to the oxorhenium(V) center. The protonation of the pyridyl nitrogens and the charge on the complex have no influence on the bond lengths and angles, with the rhenium(V)–oxo and average Re–NH bond lengths equal to 1.688(4) and 1.993(5) Å, respectively.     

Electrochemical and Spectroscopic Studies of Co(CREATININE)2Cl2

The electrochemical behavior of Co(creatinine)₂Cl₂ was investigated by cyclic voltammetry in organic solvents (DMSO and DMF) and in aqueous solution. Analysis of the results indicates that the electroactive species depend on the nature of the solvent. In DMF a single reduction process Co(II)/Co(I) is observed. In DMSO the redox behavior of the complex changes with the scan rate and a two-electron transfer process can be eventually observed. In aqueous solution the complex immediately decomposes giving rise to the aquo-cation. The characteristic peak of the redox couple Cl₂/Cl^? is observed as a consequence of the chloride released from the coordination sphere. Analysis of the electronic spectra gave additional support to the proposed mechanisms. The Co-Cl and Co-N stretching bands were clearly identified in the low frequency region of the IR spectrum.     

Phase transition and dynamics of NH3 ligands in [Zn(NH3)4](ReO4)2

One phase transition in [Zn(NH₃)₄](ReO₄)₂ at T_c = 393.5 K (on heating) and 392.0 K (on cooling) was found. Thermal stability of this compound was investigated by thermal analysis methods. It decomposes in three main stages. The first two are connected with deamination process, whereas Re₂O₇ evaporates in the last step. The activation energy for NH₃ loss processes was determined from thermogravimetric (TG) measurements. The vibrational and reorientational dynamics of NH₃ ligands in the low-temperature phase was probed by various complementary techniques. It was found that at temperatures close to 150 K, NH⋯O hydrogen bond is formed. Temperature-dependent band shape analysis of properly chosen infrared (IR) band was performed, whose results showed that activation energy for NH₃ reorientational motion (<300 K) is rather small and is approximately equal to 2 kJ mol⁻¹. Neutron and X-ray powder diffraction patterns did not reveal any drastic change in the crystal structure in a wide temperature range.     

Nickel and copper complexes of cyclopropyltetrazole: crystal structures of [Ni(C3tz)6](BF4)2 and [Cu(C3tz)6](BF4)2

Cyclopropyltetrazole (C₃tz) and its nickel(II) and copper(II) complexes [M(C₃tz)₆](BF₄)₂] were isolated and characterized by elemental analyses, electronic spectroscopy, molar conductances, magnetic susceptibilities and single-crystal X-ray analyses.     

Synthese und Kristallstruktur von Na10[P4(NH)6N4](NH2)6(NH3)0,5 mit dem adamantanartig aufgebauten Anion [P4(NH)6N4]4−

Synthesis and Crystal Structure of Na₁₀[P₄(NH)₆N₄](NH₂)₆(NH₃)_0.5 with an Adamantane-like Anion [P₄(NH)₆N₄]^4? Crystals of Na₁₀[P₄(NH)₆N₄](NH₂)₆(NH₃)_0.5 were obtained by the reaction of P₃N₅ with NaNH₂ (molar ratio 1:20) within 5 d at 600°C in autoclaves. The following data characterize X-ray investigations: Fm3 m, Z = 8, a = 15.423(2) Å, Z(F) = 261 with F ≥ 3 σ(F) Z(Variables) = 27, R/R_w = 0.086/0.089 The compound contains the hitherto unknown anion [P₄(NH)₆N₄]^4?, which resembles adamantane. The total structure can be described as follows: The centers of gravity of units of [Na₈(NH₂)₆(NH₃)]²⁺ – 8Na⁺ on the corners of a cube, 6NH₂^? on the ones of an inscribed octahedron with NH₃ in the center – follow the motif of a cubic-closest packed arrangement. Units of [Na₁₂(NH₂)₆]⁶⁺ – 12Na⁺ on the corners of a cuboctahedron and 6NH₂^? on the ones of an inscribed octahedron – occupy all octahedral and those of [P₄(NH)₆N₄]^4? all tetrahedral sites.     

Synthese und Kristallstruktur von Rb8[P4N6(NH)4](NH2)2 mit dem adamantanartigen Anion [P4N6(NH)4]6−

Synthesis and Crystal Structure of Rb₈[P₄N₆(NH)₄](NH₂)₂ with the Adamantane-like Anion [P₄N₆(NH)₄]^6? RbNH₂ reacts with P₃N₅ (molar ratio 6:1) at 400°C within 5 d to colourless Rb₈[P₄N₆(NH)₄](NH₂)₂. Suitable crystals for a X-ray structure determination were obtained: The compound contains adamantane-like molecular anions [P₄N₆(NH)₄]^6?. Their centres of gravity are arranged in a distorted hexagonal primitive array. All trigonal prisms of this array contain one amide ion. Rubidium ions connect the anions irregularly.     

Complex salts [Pd(NH3)4](ReO4)2 and [Pd(NH3)4](MnO4)2: Synthesis, structure, and thermal properties

Complex salts, i.e., tetraamminepalladium perrhenate (I) and permanganate (II), are synthesized and studied by physicochemical methods. Their crystal structures are determined and thermal analysis is performed. The products formed in thermolysis of I and II carried out in the atmosphere of helium and hydrogen are studied. The Pd_0.33Re_0.67 solid solution based on Re is shown to form under particular temperature conditions in the atmosphere of hydrogen.     

Synthesis,characterization and structure of oxorhenium(V) complexes with 2-methylmercaptobenzamide

The neutral, mononuclear complex [ReO(mta)₂Cl] (1) [Hmta?=?2-(methylmercapto)aniline] was prepared by reaction of trans-[ReOCl₃(PPh₃)₂] with a twofold molar excess of Hmta in methanol. The oxo-bridged dimer (μ-O)[ReO(mta)₂]₂ (2) was synthesized by reacting [ReOCl₃(PPh₃)₂] with a twofold excess of Hmta in a 9?:?1 acetone/water mixture. The compounds were characterized by spectroscopy and complex 1 also by X-ray crystallography. Complex 1 has a distorted octahedral geometry with the chloride coordinated trans to the oxo group, and with the chelating ligands in the equatorial plane in a cis-N cis-S configuration.     

钒(V)化合物在硫酸中的电化学行为研究

应用循环伏安法和旋转环盘电极法研究了H2 SO4 溶液中五价钒化合物 (NH4 VO3和V2 O5)的电化学行为 .由光滑Pt电极测得其CV图 ,两者的基本峰位和峰形都很相似 ,通常出现三个还原峰和三个氧化峰 ,但NH4 VO3多一个氧化峰 ,RRDE测定也出现了四个氧化峰 ,本文分析了这些对应峰的反应 ,并给予初步解释     

Syntheses,Spectral, Thermal and Electrochemical Studies of 3-Carboxylacetonehydroxamic Acid and its Iron(Ii), Cobalt(Ii), Nickel(Ii), Copper(Ii) and Zinc(Ii) Complexes

3-Carboxylacetonehydroxamic acid (CAHA) and its iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes were synthesized and characterized by elemental analysis, UV-Vis and IR spectra and magnetic susceptibility. The pK _a1 and pK _a2 values of the ligand in aqueous solution were found to be 6.5 ± 0.1 and 8.6 ± 0.1, which correspond to dissociation of carboxyl and hydroxamic protons, respectively. The dianion CAH acts as a tetradentate ligand through the hydroxamate and carboxylate groups and coordinates to the divalent metal ions, forming coordination polymers with a metal-to-ligand ratio of 1 : 1 in the solid state. FTIR spectra and thermal decomposition of the ligand and its metal complexes were recorded and briefly discussed. The electrochemical behavior of the complexes was investigated by square wave voltammetry and cyclic voltammetry at neutral pH. In contrast to the solid state, the iron(II) and copper(II) cations form stable complex species with a metal-to-ligand ratio of 1 : 2 in solution. The iron(II), cobalt(II) and nickel(II) complexes show two-electron irreversible reduction behavior, while the copper(II) and zinc(II) complexes undergo quasi-reversible and reversible electrode reactions, respectively. The stability constants of the complexes were determined by square wave voltammetry.     

Darstellung und Kristallstrukturen von Ag[N(CN)2](PPh3)2, Cu[N(CN)2](PPh3)2 und Ag[N(CN)2](PPh3)3

Preparation and Crystal Structures of Ag[N(CN)₂](PPh₃)₂, Cu[N(CN)₂](PPh₃)₂, and Ag[N(CN)₂](PPh₃)₃ The coordination compounds Ag[N(CN)₂](PPh₃)₂ ( 1 ), Cu[N(CN)₂](PPh₃)₂ ( 2 ), and Ag[N(CN)₂](PPh₃)₃ ( 3 ) are obtained by the reaction of AgN(CN)₂ or CuN(CN)₂ with triphenylphosphane in CH₂Cl₂. X‐ray structure determinations were performed on single crystals of 1 , 2 , and 3 · C₆H₅Cl. The three compounds crystallize monoclinic in the space group P2₁/n with the following unit cell parameters. 1 : a = 1216.07(9), b = 1299.5(2), c = 2148.4(3) pm, β = 99.689(13)°, Z = 4; 2 : a = 1369.22(10), b = 1257.29(5), c = 1888.04(15) pm, β = 94.395(7)°, Z = 4; 3 · C₆H₅Cl: a = 1276.6(4), b = 1971.7(3), c = 2141.3(5) pm, β = 98.50(3)°, Z = 4. In all structures the metal atoms have a distorted tetrahedral coordination. The crystal structure of 3 · C₆H₅Cl shows monomeric molecular units with terminal coordinated dicyanamide. The crystal structure of 1 is built up by dinuclear units, which are bridged by dicyanamide ligands. However, the crystal structure of 2 corresponds to a onedimensional coordination polymer, bridged by dicyanamide anions.     

Electron Transfer Studies of TIN(IV)/TIN(II) in Acid Media

Abstract

Cyclic voltammaetry of mixed tin(II)/tin(IV) solutions was investigated in 6M HCl on gold and mercury electrodes. It was found that the reduction of tin(II) to tin(iv) proceeded irreversibly while tin(II) to tin(IV) was reversible. Two forms of tin(IV) are postulated. The peak potential for the reduction of tin(IV) was a function of both tin(II) and tin(IV) while that for the oxidation of tin(II) was a function only of tin(II) concentration Potentials for all oxidations and reductions were a function of potential scan rate.     

Die Kristallpackung in drei Modifikationen von PPh4[ReO(S4)2] und PPh4[ReS(S4)2]

The Crystal Packing in three Modifications of PPh₄[ReO(S₄)₂] and PPh₄[ReS(S₄)₂] Mixed crystals PPh₄[ReS(S₄)₂]_0,63[ReO(S₄)₂]_0,37 were obtained from PPh₄Cl, ReCl₅ and Na₂S₄ in acetonitrile. Their crystal structure corresponds to the known structure of this kind of compound (space group P2₁/n). In a similar reaction with ReBr₅ instead of ReCl₅, PPh₄[ReO(S₄)₂] was obtained in small yield. Its triclinic crystal structure was determined by X‐ray crystallography (space group P1). It contains cation pairs (PPh₄⁺)₂ such as they have been found in many other instances. In contrast, the crystal structures of the mixed crystals and of one known modification of PPh₄[ReS(S₄)₂] have PPh₄⁺ columns similar to compounds crystallizing in the space group P4/n, albeit in a severely distorted manner; their space group P2₁/n is a subgroup of P4/n with a doubled unit cell. In another modification of PPh₄[ReS(S₄)₂] (space group P2₁/c) the columns are less distorted, but arranged in a different way.     

硫醇在金电极上的SA单分子层膜的电化学研究

金基底上的硫醇自组装单分子层膜(Self-asembledmonolayers,SAMs)具有良好的稳定性和有序性,因此在基础研究及应用技术等领域都受到了广泛的重视^[1].通过电化学方法测定自组装膜对溶液中电活性物质的异向电子转移的阻碍作用.     

Synthesis of [M(NH3)5Cl](ReO4)2 (M = Cr, Co, Ru, Rh, Ir) and investigation of thermolysis products. Crystal structure of [Rh(NH3)5Cl](ReO4)2

Complex salts [M(NH₃)₅Cl](ReO₄)₂, where M = Cr, Co, Ru, Rh, Ir, have been prepared. The crystal structure of [Rh(NH₃)₅Cl](ReO₄)₂ was determined by single crystal X-ray diffraction. Crystal data: a = 17.369(4) Å, b = 7.7990(16) Å, c = 11.218(2) Å, V = 1430.5(5) ų, space group C2/m, Z = 4, d _calc = 3.19 g/cm³, R = 0.0447. Complex salts from the above series are shown to be isostructural; they were defined by X-ray crystallography. Thermal decomposition of the compounds in an inert atmosphere and under hydrogen has been studied. According to X-ray phase analysis (XRPA) data, the M_0.33Re_0.67 (M = Co, Ru, Rh, Ir) monophase solid solutions are the products of reduction of the salts under hydrogen.