Synthesis,structure, and some reactions of the cluster complex [(μ-H)<Subscript>2</Subscript>Fe<Subscript>5</Subscript>(μ<Subscript>3</Subscript>-Se)<Subscript>2</Subscript>(CO)<Subscript>14</Subscript>]

In the reaction of Na₂Se with [Fe(CO)₅] in isopropanol with subsequent acidification with HCl, which is used to synthesize [(μ-H)₂Fe₃(μ₃-Se)(CO)₉] (II), the cluster [(μ-H)₂Fe₅(μ₃-Se)₂(CO)₁₄] (I) was detected. In assumption that compound I could serve as a suitable synthon for preparing the bulky heterometallic clusters, its reactions with the Rh-containing complexes were studied. The reaction of I with [Rh(CO)₂Cp*] (Cp* is pentamethylcyclopentadienyl) was found to give a mixture of the products. The main reaction products were isolated and their structures were determined: [Fe₂Rh(μ₃-Se)₂(CO)₆Cp*], [Fe₂Rh(μ₃-Se)(μ₃-CO)(CO)₆Cp*], [FeRh₂(μ₃-Se)(μ-CO)(CO)₃Cp ₂ ^* ], [Fe₂Rh₂(μ₄-Se)(μ-CO)₄(CO)₂Cp ₂ ^* ]. Potassium hydride treatment of II with subsequent addition of [Cp*Rh(CH₃CN)₃](CF₃SO₃)₂ leads to the well-known cluster complex [Fe₃Rh(μ₄-Se)(CO)₉Cp*]. A set of the reaction products indicates that the {Fe₅Se₂} core cannot be used as one-piece “building block” in the synthesis of heterometallic clusters.     

Thermodynamic characteristics of europium pivalate binuclear complexes Eu<Subscript>2</Subscript>(Piv)<Subscript>6</Subscript> and [Eu<Subscript>2</Subscript>(Piv)<Subscript>6</Subscript> · (Phen)<Subscript>2</Subscript>]

Sublimation of europium pivalate binuclear complexes Eu₂(Piv)₆ and [Eu₂(Piv)₆ · (Phen)₂] (Piv = (CH₃)₃CCOO, Phen = C₁₂H₈N₂) in the temperature range of 383–660 K is studied by the Knudsen effusion method with mass-spectrometric analysis of the gas phase. The vaporization of Eu₂(Piv)₆ is shown to be accompanied by polymerization and the formation of Eu₂(Piv)₆ and Eu₄(Piv)₁₂ molecules. The saturated vapor over the mixed-ligand complex of europium pivalate with o-phenanthroline consists of Phen, Eu₂(Piv)₆, and Eu₄(Piv)₁₂ molecules. The partial pressures of the gas components, as well as the standard enthalpies of sublimation and dissociation of the reaction proceeding with removal of phenanthroline have been determined.     

Nonisothermal decomposition kinetics of [CoC<Subscript>2</Subscript>O<Subscript>4</Subscript>·2.5H<Subscript>2</Subscript>O]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

The authors present their results concerning the decomposition in air of the homopolynuclear coordination compound [CoC₂O₄·2.5H₂O] _n . In the temperature range 20–300 °C, the heating curves TG, DTG and DTA allowed to evidence three decomposition steps. The kinetic analysis was performed on the second step which proved to be the only workable one. The application of nonlinear regression procedure shows that this is a complex process consisting in three successive steps. The checking of the mechanism and corresponding kinetic parameters for quasi-isothermal data (T = 150 °C) shows that the obtained results could be used for prediction of the thermal behaviour of the investigated compound in both isothermal and non-isothermal conditions.     

Phase complex of a NaCl—KCl—SrCl<Subscript>2</Subscript>—Sr(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> four-component system and the physicochemical properties of a eutectic mixture

Tree of phases and crystallization were plotted via a priori prediction, and the coordinates (composition) of a nonvariant point of a NaCl-KCl-SrCl₂-Sr(NO₃)₂ four-component system were determined according to calculations and experimental data. The promise of the method for determining the coordinates of nonvariant points in multicomponent systems was confirmed experimentally. The dependence of density and electroconductivity vs. temperature was studied. The volume dilation of a melt was calculated up to the maximum operating temperature.     

Large magnetic anisotropy of chromium(III) ions in a bis(ethylenedithio)tetrathiafulvalenium salt of chromium bis(dicarbollide), (ET)<Subscript>2</Subscript>[3,3′-Cr(1,2-C<Subscript>2</Subscript>B<Subscript>9</Subscript>H<Subscript>11</Subscript>)<Subscript>2</Subscript>]

The synthesis of a radical-cation salt based on a derivative of tetrathiafulvalene, (ET)₂[3,3′-Cr(1,2-C₂B₉H₁₁)₂] (ET?=?bis(ethylenedithio)tetrathiafulvalenium), was accomplished by electrochemical anodic oxidation of ET in the presence of (Me₄N)[3,3´-Cr(1,2-C₂B₉H₁₁)₂] in the galvanostatic regime. An electric conductivity σ (293 K)?=?7 × 10^?3 Ohm^?1 cm^?1 with semiconductor activation energy E_a???0.1 eV in the range of 127–300 K was observed. The crystal structure of (ET)₂[3,3′-Cr(1,2-C₂B₉H₁₁)₂] was determined by X-ray diffraction at 173 K, revealing the presence of structural tetramers in radical-cation stacks. The magnetic properties of the complex were investigated in the temperature range 1.8–300 K using magnetometry and EPR, showing that the magnetic structure of (ET)₂[3,3′-Cr(1,2-C₂B₉H₁₁)₂] consists of two independent magnetic subsystems. Cation radicals form a rectangular magnetic lattice in the ab-plane with significant antiferromagnetic exchange interactions. The chromium bis(dicarbollide) anions are characterized by unusually strong positive zero-field splitting of the Cr(III) ions, which was confirmed by ab initio calculations.     

Hydrothermal synthesis and crystal structure of a tungstovanadate: [4,4′-bipyH<Subscript>2</Subscript>][4,4′-bipyH]<Subscript>2</Subscript>[VW<Subscript>12</Subscript>O<Subscript>40</Subscript>] · 4,4′-bipy · 7.5H<Subscript>2</Subscript>O

An organic-inorganic hybrid Keggin compound, [4,4′-bipyH₂][4,4′-bipyH]₂[VW₁₂O₄₀] · 4,4′-bipy · 7.5H₂O (bipy-bipyridine) (1), has been prepared under hydrothermal conditions and characterized by IR spectroscopy, single crystal X-ray diffraction, thermal analysis, and ESR spectroscopy. 1 crystallized in the monoclinic space group P2₁/c with a = 18.7350(15) Å, b = 14.0253(12) Å, c = 26.434(2) Å, β= 105.0810(10)°, V = 6706.6(10) ų and Z = 4. The crystal structure of 1 consists of diprotonated and monoprotonated 4,4′-bipyridine cations, free 4,4′-bipyridine molecule, lattice water molecules, and a typical Keggin-type polyoxoanion [VW₁₂O₄₀]^4?. The polyoxoanion is constructed by four {W₃O₁₆} trinuclear groups, each of which is made up of three edge-sharing {WO₆} octahedra, and the {VO₄} tetrahedron is in the center of the cage.     

In Situ: 2-D Inorganic Layer Lead-MOF Built from [(<Emphasis Type="Italic">μ</Emphasis><Subscript>4</Subscript>-O)Pb<Subscript>4</Subscript>] Core

In situ lead-MOF derived from 2-Methyl-3-acetylnaphtho[2,3-b]furan-4,9-dione (MAFD), [Pb₇O₂(OH)₂(1,2-BDC)₄(H₂O)] 1, 1,2-BDC = C₆H₄(COOH)₂, phthalic acid, has been synthesized and characterized by elemental analysis, IR, TG-DTA, powder X-ray diffraction (XRD) and single crystal X-ray diffraction. Compound 1 possesses 2-D inorganic layer structure built from rare tetranuclear unit [(μ ₄-O)Pb₄]. In 1, both crystallographic distinct Pb(1) and Pb(4) ions adopt six-coordination geometry, and the other two crystallographic distinct Pb(2) and Pb(3) ions display eight-coordination geometry under the condition of Pb–O bond length extended to 3.10 Å. A 3-D supramolecular network is also formed by hydrogen bonds (C–H···O). Result of photoluminescence measurement indicates an emission band at 385 nm (λ _excitation = 209 nm).     

Crystal structures of [RhL<Subscript>4</Subscript>Cl<Subscript>2</Subscript>][AuCl<Subscript>4</Subscript>] (L = Py, γ- and β-picolines) complex salts

New double complex salts [RhL₄Cl₂][AuCl₄] (L = Py, γ- and β-picolines) are synthesized. The compounds are characterized by elemental, powder and single crystal X-ray diffraction analyses. The salts crystallize in different space groups. A specific feature of the packing of [AuCl₄]^– complex anions is the chain formation due to additional Au…Cl or Cl…Cl contacts.     

The state of dispersed niobia species on γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and their catalytic performance for condensation of isobutylene and isobutyraldehyde

Catalysts of Nb₂O₅/γ-Al₂O₃ were prepared by aqueous solution impregnation. The state of niobia species on surface of γ-Al₂O₃ is characterized by using the technology of X-ray power diffraction (XRD) and analyzed using the “incorporation model”. The acidity and the nature of acid sites of the catalysts were evaluated by means of Fourier transform infrared (FTIR) spectroscopy of adsorbed pyridine. The catalytic activity of Nb₂O₅/γ-Al₂O₃ catalysts was evaluated by a condensation reaction from isobutene and isobutyraldehyde to 2,5-dimethyl-2,4-hexadiene. The results of XRD indicate that the dispersion capacity of niobia on γ-Al₂O₃ is about 0.76 mmol Nb per 100m² γ-Al₂O₃, which is almost identical to the theoretical value (0.75 mmol Nb per 100m² γ-Al₂O₃) calculated by the “incorporation model”. The results of Py-IR and catalytic activity evaluation indicate that the acidity feature is related to the state of dispersed niobia species as well as the loading of niobia onto the surface of γ-Al₂O₃ support.     

[Bmim]<Subscript>5</Subscript>[PNiW<Subscript>11</Subscript>O<Subscript>39</Subscript>]·3H<Subscript>2</Subscript>O an organic–inorganic hybrid as catalyst for one-pot pseudo-five-component synthesis of tetrazolyldiazepines

In this research, two heterogeneous organic–inorganic hybrid catalysts, [bmim]₃[PW₁₂O₄₀]·3H₂O and [bmim]₅[PNiW₁₁O₃₉]·3H₂O, have been prepared. The catalysts were fully characterized by several techniques such as elemental analyses, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, scanning electron microscope and energy-dispersive X-ray analysis. Next, the hybrid catalysts have been used for the synthesis of functionalized diazepines containing tetrazole ring. Tetrazolyl-1H-spiro[benzo[b]cyclopenta[e][1,4] diazepines products were obtained in excellent yields and mild experimental conditions using [bmim]₅[PNiW₁₁O₃₉]·3H₂O as catalyst. This process was carried out via a one-pot, pseudo-five-component condensation reaction by means of a 1,2-diamine, isocyanide, TMSN3 and two molecules of a linear or cyclic ketone in methanol, at ambient temperature.     

Two decomposition mechanisms of nitrosyl iron complexes [Fe<Subscript>2</Subscript>(μ-SR)(NO)<Subscript>4</Subscript>]

Two decomposition mechanisms of nitrosyl iron complexes (NICs) [Fe₂(μ-SR)(NO)₄] in aqueous medium are known. One mechanism (for instance, in the case of complex [Fe₂(μ-SC₄H₃N₂)₂(NO)₄]) involves irreversible and rapid hydrolysis of NIC with the NO release accompanied with the formation of the products of further NO transformations. In the other mechanism (for instance, in the case of complexes [Fe₂(μ-S(CH₂)₂NH₃)₂(NO)₄]SO₄? ?2.5H₂O and [Fe₂(μ-SC₅H₁₁NO₂)₂(NO)₄]SO₄?5H₂O), no hydrolysis occurs but NICs reversibly dissociate to release both NO and thiolate ligand into the medium. In the present work, the difference in the mechanisms of the NIC decomposition is explained by the difference in the NIC redox potentials. The experimental evidences of this fact are given.     

Crystal structure of the ruthenium(II) nitrosotrichloro complex Na[RuNOCl<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)OH]·2H<Subscript>2</Subscript>O

The crystal structure of the coordination compound Na[RuNOCl₃(H₂O)OH]·2H₂O is reported. The complex is studied by IR and NMR spectroscopy, powder and single crystal X-ray diffraction. Crystallographic data determined for H₇Cl₃NNaO₅Ru is: a = 6.648(2) ?, b = 8.216(7) ?, c = 10.063(3)?, α= 89.75(6)°, β = 70.96(2)°, γ = 78.76(5)°, V = 967.9(2) ?³, P1 space group, Z = 4, d _x = 2.165 g/cm³.     

Synthesis of dicationic μ-diborolyl triple-decker complexes [CpCo(μ-1,3-C<Subscript>3</Subscript>B<Subscript>2</Subscript>Me<Subscript>5</Subscript>)M(C<Subscript>6</Subscript>H<Subscript>6</Subscript>)]<Superscript>2+</Superscript> (M = Rh,Ir)

Dicationic triple-decker complexes [CpCo(μ-1,3-C₃B₂Me₅)M(C₆H₆)]²⁺ (M = Rh (3), Ir (4)) were synthesized by the reaction of [CpCo(μ-C₃B₂Me₅)MBr₂]₂ (M = Rh, Ir) with benzene in the presence of AgBF₄. The structure of 3(BF₄)₂ was determined by X-ray diffraction analysis.     

A novel series of sulphur-bridged ruthenium-molybdenum complexes: [(RaaiR′)<Subscript>2</Subscript> Ru(μ-S)<Subscript>2</Subscript>Mo(OH)<Subscript>2</Subscript>]. Synthesis,spectroscopic and electrochemical characterization. RaaiR′=1-alkyl-2-(arylazo) imidazole

The reaction of ctc-[Ru(RaaiR′)₂Cl₂] (1) [RaaiR′ = 1-alkyl-2-(arylazo)imidazole, p-R-C₆H₄-N=N-C₃H₂NN(1)-R′, R = H (a), Me (b), Cl (c), R′ = Me (2), Et (3), Bz (4)] with (NH₄)₂MoS₄ in aqueous MeOH afforded red-violet mixed ligand complexes of the type [(RaaiR′)₂Ru(μ-S)₂Mo(OH)₂] (2–4). In complexes (2–4) the terminal Mo=S bonds of the MoS₄²⁻ unit become hydroxylated and the molybdenum ion is reduced from the starting Mo^VI in MoS₄²⁻ to Mo^IV in the final product (2–4). The solution electronic spectra exhibit a strong MLCT band at 550–570 nm in DCM. Cyclic voltammograms show a Ru(III)/Ru(II) couple at 1.10–1.4 V, irreversible Mo(IV)/Mo(V) oxidations in the 1.66–1.72 V range, along with four successive reversible ligand reductions in the range −0.45–0.67 V (one electron), −0.82–1.12 V (one electron), and −1.44–1.90 V (simultaneously two electrons).     

Novel crystal modification of <Emphasis Type="Italic">fac</Emphasis>-triamminetrinitrorhodium(III) — β-<Emphasis Type="Italic">fac</Emphasis>-[Rh(NO<Subscript>2</Subscript>)<Subscript>3</Subscript>(NH<Subscript>3</Subscript>)<Subscript>3</Subscript>]

The paper describes the preparation techniques for β-fac-[Rh(NO₂)₃(NH₃)₃]. The complex crystallizes as colorless prisms belonging to the monoclinic crystal system. Crystal data: a = 6.6338(2) Å, b = 11.0627(3) Å, c = 11.5314(3) Å; β = 96.608(1)°, V = 840.64(4) ų, space group P2₁/n, Z = 4, d_calc = 2.308 g/cm³. The structure is molecular and contains neutral complex molecules having the fac configuration. Crystal chemical analysis of the complex in comparison to α-fac-[Rh(NO₂)₃(NH₃)₃] is performed.     

Synthesis and structure of antimony compounds (Ph<Subscript>3</Subscript>SbBr)<Subscript>2</Subscript>O · 2PhH and [(2-MeC<Subscript>6</Subscript>H<Subscript>4</Subscript>)<Subscript>3</Subscript>SbBr]<Subscript>2</Subscript>O · 0.5PhH

Hydrolysis of triphenylantimony dibromide or tri(o-tolyl)antimony dibromide in benzene yields the solvates (Ph₃SbBr)₂O · 2PhH (triclinic modification) (I) and [(2-MeC₆H₄)₃SbBr]₂O · 0.5PhH (II), in which the Sb atoms have a distorted trigonal-bipyramidal coordination. The aryl ligands are in the equatorial positions; the bridging oxygen atom and the terminal Br ligands occupy the axial positions. The bond lengths in I: Sb-C, 2.103(2)–2.125(2) Å, Sb-O, 1.976(1) and 1.979(1); and Sb-Br, 2.7128(2) and 2.7592(2) Å. The bond lengths in II (Å): Sb-C, 2.109(6)–2.145(3) Å; Sb-O, 1.954(4)–1.958(4) Å; and Sb-Br, 2.7355(8)–2.7624(7) Å. The angles SbOSb are equal to 138.83(6)° in I and 170.8(3)° and 161.6° in II.     

Ab initio and DFT conformational study on nitrosamine (H<Subscript>2</Subscript>N–N=O) and <Emphasis Type="Italic">N</Emphasis>-Nitrosodimethylamine [(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>N–N=O]

Abstract  

Ab initio and DFT calculations have been performed to characterize some ground state structures of the title molecules. Relative energies, rotational barriers, NBO charges, and dipole moments (μ) have been calculated and analyzed. It has been confirmed that only highly correlated methods (e.g., CCSD) are able to yield the non-planar structure as a minimum, for the H₂NNO molecule. On the other hand, all computational levels here employed are able to yield a planar C₂NNO frame for the (CH₃)₂NNO as a minimum. Important correlations between atomic charges and bond distances are discussed. Replacement of H by methyl group increases the rotational barrier and μ values by at least 3 kcal/mol and 0.4 D, respectively. The largest μ values are obtained for the structures in which the nitrogen lone pair is parallel to the NO group π system, and are consistent with a larger contribution of a dipolar resonance structure.     

Elaboration,Structural, Vibrational,DSC Investigations and Hirshfeld Surface Analysis of New Organic–Inorganic Hybrid Compound: [H<Subscript>2</Subscript>mela]Cu<Subscript>2</Subscript>Br<Subscript>6</Subscript>

The present paper accounts for the synthesis, crystal structure, differential scanning calorimetry and vibrational spectroscopy of a new compound (1,3,5-triazinidium-2,4,6-triamine) hexabromidodicuprate (II) grown at room temperature by slow evaporation of aqueous solution. From X-ray diffraction data collected at room temperature, it is concluded that it crystallizes in the monoclinic system (P2₁/c space group). The anion and the cation are linked by N–H···Br hydrogen bonds. Furthermore, the room temperature IR and Raman spectra of the title compound were recorded and analyzed. The differential scanning calorimetric has also been investigated. Hirshfeld surfaces were used to confirm the existence of inter-molecular interactions in the compound.     

Thermal and thermomechanical properties of trialkylammonium dodecahydro-<Emphasis Type="Italic">closo</Emphasis>-dodecaborates (R<Subscript>3</Subscript>NH)<Subscript>2</Subscript>[B<Subscript>12</Subscript>H<Subscript>12</Subscript>] (R = Et, Вu)

This work is devoted to specific features of the thermal and thermomechanical properties of trialkylammonium salts of the [B₁₂H₁₂]^2– anion (R₃NH)₂ [B₁₂H₁₂], where R = Et, Вu, and is of fundamental importance for the development of composite materials with an increased boron content. The results are given in comparison with similar data for (Et₃NH)₂[B₁₀H₁₀].