Interaction of [В<Subscript>10</Subscript>H<Subscript>10</Subscript>]<Superscript>2–</Superscript> and [В<Subscript>12</Subscript>H<Subscript>12</Subscript>]<Superscript>2–</Superscript> with nitro compounds

The interaction of the [B₁₀H₁₀]^2– and [B₁₂H₁₂]^2– anions with aliphatic and aromatic nitro compounds (RNO₂, where R = Et, n-Pr, i-Pr, tert-Bu, Ph) has been studied under irradiation with visible and UV light. It has been shown that, depending on the reaction conditions, both mono- and disubstituted nitro-closo-decaborates can be selectively obtained in yields up to 50%.     

Nucleophilic addition of aromatic amide oximes to [2-B<Subscript>10</Subscript>H<Subscript>9</Subscript>NCC<Subscript>2</Subscript>H<Subscript>5</Subscript>]<Superscript>–</Superscript> anion

A series of closo-decaborate anions containing an O-iminoacylamide oxime fragment were synthesized by nucleophilic addition of aromatic amide oximes to 2-propionitrilium closo-decaborate anion. The isolated compounds were characterized by IR, ¹H, ¹³C–{¹H}, and ¹¹B–{¹H} NMR, and mass spectra. The structure of (Ph₄P)[2-B₁₀H₉NH=C(Et)ON=C(NH₂)C₆H₄Me-2] was determined by single-crystal X-ray analysis.     

Photochemical arene exchange in the naphthalene complex [CpRu(η<Superscript>6</Superscript>-C <Subscript>10</Subscript>H<Subscript>8</Subscript>)]<Superscript>+</Superscript>

The cation [CpRu(η⁶-C₁₀H₈)]⁺ was shown to exchange naphthalene for other arenes under visible-light irradiation to form the complexes [CpRu (η⁶-arene)]⁺ (arene = C₆H₆, 1,4-C₆H₄Me₂, 1,3,5-C₆H₃Me₃, or 1,2,4,5-C ₆H₂Me₄) in 70–95% yields. The reaction rate of exchange decreases in the series arene = 1,4-C₆H₄Me₂ > C₆H₆ > 1,3,5-C₆H₃Me₃ > 1,2,4,5-C ₆H₂Me₄ >> C₆Me₆ and increases with the coordinating ability of the solvent in the order CH₂Cl₂ < THF—CH₂Cl₂ mixture (1: 1) < acetone.     

Experimental Determination of the Isotherm at 15°C of the System Mg<Superscript>2+</Superscript>/Cl<Superscript>−</Superscript>, SO<Subscript>4</Subscript><Superscript>2</Superscript>–H<Subscript>2</Subscript>O

Summary.  The diagram of the ternary system Mg²⁺/Cl⁻, SO₄ ²⁻–H₂O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram, which are MgSO₄·6H₂O, MgSO₄·7H₂O, and MgCl₂·6H₂O. The solubility field of MgSO₄·7H₂O is important whereas those of MgSO₄·6H₂O and MgCl₂·6H₂O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO₄:MgCl₂=2.73:33.80 and MgSO₄: MgCl₂=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg²⁺/Cl⁻, SO₄ ²⁻–H₂O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C.  Corresponding author. E-mail: ariguib@planet.tn Received October 16, 2002; accepted (revised) December 3, 2002 Published online April 24, 2003 RID="a" ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70^th birthday     

The ESCA analysis of the B<Subscript>3</Subscript>H<Stack><Subscript>8</Subscript><Superscript>−</Superscript></Stack> anion

Compounds [Et₄N]₂B₃H₈ and CsB₃H₈ are studied using the ESCA method. The results of analysis of the B1s electron spectra and estimation of the effective charge differences in [Et₄N]₂B₃H₈ are compared to the data of theoretical calculations of the B₃H₈⁻ anion.     

Thermal arene exchange in the naphthalene complex [CpRu(η<Superscript>6</Superscript>-C<Subscript>10</Subscript>H<Subscript>8</Subscript>)]<Superscript>+</Superscript>

Naphthalene in the [CpRu(⁶−C₁₀H₈)]⁺ complex (1) is substituted for other arenes under reflux in 1,2-dichloroethane to form the [CpRu(⁶-arene)]⁺ cations (arene = C₆H₆, 1,2-C₆H₄Me₂, 1,2,4,5-C₆H₂Me₄, or C₆Me₆) in 70–80% yields. The reaction is accelerated in the presence of a catalytic amount of acetonitrile. The structure of [1]PF₆ was established by X-ray diffraction.     

<Superscript>35</Superscript>Cl NQR for the SbCl<Subscript>3</Subscript> complex with aniline,SbCl<Subscript>3</Subscript>·NH<Subscript>2</Subscript>C<Subscript>6</Subscript>H<Subscript>5</Subscript>

The temperature dependence of the ³⁵Cl NQR frequencies and spin-lattice relaxation times has been investigated for a trigonal-bipyramidal vn complex SbCl₃·NH₂C₆H₅. Thermally activated motion of chlorine atoms (pseudorotation) was not revealed in the complex, in contrast to the vπ complexes of SbCl₃ with related molecular structures. The high potential barrier of pseudorotation in the aniline complex is likely to be due to the unusually high nonequivalence of Sb-Cl chemical bonds.     

A new method of synthesis of the B<Subscript>3</Subscript>H<Stack><Subscript>8</Subscript><Superscript>−</Superscript></Stack> anion

A new method of synthesis of the B₃H₈⁻ anion has been suggested. The method uses the reaction of some metal halides (CuCl, SnCl₂, CrCl₃, PbF₂, PbCl₂, PbBr₂, and BiCl₃) with sodium tetrahydroborate. It is characterized by high (up to quantitative) yields and simplicity of isolation of the target products ((n-C₄H₉)₄N)[B₃H₈] and Cs[B₃H₈].     

Thermogravimetric analysis of wheatleyite Na<Subscript>2</Subscript>Cu<Superscript>2+</Superscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>·2H<Subscript>2</Subscript>O

Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates. These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC₂O₄ as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite Na₂Cu²⁺(C₂O₄)₂·2H₂O. High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and 857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II) oxalate as compared to the synthetic compound which is the dihydrate.     

Structural characterization of two lanthanide complexes attached to [H<Subscript>2</Subscript>W<Subscript>12</Subscript>O<Subscript>40</Subscript>]<Superscript>6−</Superscript>

In this article, two compounds [H₂bpy][Ln(DMF)₄(H₂O)₃(Hbpy)][H₂W₁₂O₄₀] (Ln = La,Ce; DMF = N,N-dimethylformamide, bpy = 4,4′-bipyridine) have been synthesized and characterized by single-crystal X-ray diffraction, IR spectra, and TG analysis. X-Ray analysis showed that the [Ln(DMF)₄(H₂O)₃(Hbpy)]⁴⁺ unit is supported on the α-Keggin polyoxoanion [H₂W₁₂O₄₀]⁶⁻ via the surface bridging oxygen atom. The [H₂bpy][Ln(DMF)₄(H₂O)₃(Hbpy)][H₂W₁₂O₄₀] entity is further extended into 2D supramolecular networks with 1-D channels by hydrogen-bonding interactions, in which 4,4′-bipy ligands reside. To the best of our knowledge, these complexes represent the first examples of rare earth metal-organic complex-decorated α-metatungstate clusters. Furthermore, the electrochemical properties of these compounds have been studied via the method of bulk-modified carbon paste electrodes.     

Mercury complex [(HOCH<Subscript>2</Subscript>)<Subscript>3</Subscript>CNH<Subscript>3</Subscript>]<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> [HgI<Subscript>4</Subscript>]<Superscript>2−</Superscript>: Synthesis and structure

The complex [(HOCH₂)₃CNH₃] ₂ ⁺ [HgI₄]^2? (I) was synthesized by reacting (trioxymethyl)methylammonium iodide with mercury dioide (2: 1 mol/mol) in acetone. X-ray crystallography shows that the complex consists of two types of crystallographically independent [(HOCH₂)₃CNH₃]⁺ cations and tetrahedral anions [HgI₄]^2? (IHgI, 106.49(2)°–113.99(4)°; Hg-I, 2.7849(8)-2.8105(8) Å. [(HOCH₂)₃CNH₃]⁺ cations are linked via hydrogen bonds O…H-N and O-H…N (O…N, 2.84–2.92 Å) to form polymer chains, which are cross-linked with one another via anions (I…H, 2.81, 2.82 Å).     

A molecular dynamics simulation of H<Subscript>3</Subscript>PO<Subscript>4</Subscript>, H<Subscript>2</Subscript>PO<Stack><Subscript>4</Subscript><Superscript>−</Superscript></Stack>, and the protonated form of N,N-dimethylformamide in liquid N,N-dimethylformamide

The molecular dynamics simulation method was for the first time used to study the structural and energy parameters of H₃PO₄, H₂PO₄⁻, and (DMFA)H⁺ (protonated dimethylformamide) in liquid N,N-dimethylformamide. The predominant orientation of the nearest neighbors of H₃PO₄, H₂PO₄⁻, DMFA, and (DMFA)H⁺ was determined from ranked distribution functions. The most probable structure of H-bonded complexes was obtained. It was shown that H₃PO₄ formed H-bonds with two DMFA molecules, and and (DMFA)H⁺ formed H-bonds with one molecule. The dependence of Coulomb interaction energies on the distance between H₃PO₄, H₂PO₄⁻, (DMFA)H⁺, and DMFA had the form of damped oscillations, as is characteristic of intermolecular interactions in pure DMFA. The molecular dynamics simulation of the H₂PO₄⁻-(DMFA)H⁺-DMFA ternary system showed a high probability of the formation of contact ion pairs.     

Crystal structure of Pb<Subscript>2</Subscript>[Fe(CN)<Subscript>6</Subscript>]NO<Superscript>3</Superscript>·5.5H<Subscript>2</Subscript>O

Synthesis of a mixed complex compound Pb₂[Fe(CN)₆]NO₃·5.5H₂O is described. The results of its X-ray structural investigation are presented. Crystal data: C₆H₁₁FeN₇O_8.50Pb₂: a = 7.2582(6) Å, b = 21.838(3) Å, c = 11.612(1) Å; β = 107.91(1)°, V = 1751.4(3) ų, Z = 4, d_calc = 2.986 g/cm³, space group P2₁/m, R = 0.038. The compound has a framework polymer structure.     

Crystal structure of glycine phosphite C<Subscript>2</Subscript>H<Subscript>5</Subscript>NO<Subscript>2</Subscript>·H<Subscript>3</Subscript>PO<Subscript>3</Subscript>

Single crystal X-ray diffraction study of glycine phosphite C₂H₅NO₂·H₃PO₃ was performed (monoclinic, space group P2₁/c, a = 7.401(3) Å, b = 8.465(3) Å, c = 9.737(3) Å; β = 100.73(5)°, Z = 4). It has been found that one of hydrogen atoms is located at the centre of symmetry forming two strong hydrogen bonds to yield H₄P₂O ₆ ^?2 dimers, while another hydrogen atom is statistically disordered over two positions and organizes the dimers into an infinite corrugated chain. The ordering of this hydrogen atom position and/or displacement of the other one from the centre of symmetry will lead to the loss of symmetry centre and lowering of the point group symmetry from C_2h to piezo-active group C₂ or C _s .     

Sr<Superscript>+</Superscript> + H<Subscript>2</Subscript>O ↔ SrOH<Superscript>+</Superscript> + H equilibrium in flames with strontium admixtures

Sr⁺ + H₂O ↔ SrOH⁺ + H equilibrium was studied spectrophotometrically. This reaction occurs in natural gas combustion products. Its enthalpy Δ_r H ^○(0) = 61.4 ± 2.8 kJ/mol and bond energy D ₀(Sr⁺-OH) = 432.6 ± 2.8 kJ/mol were determined using the third law of thermodynamics. The experimental data on this reaction obtained earlier in hydrogen flames, Δ_r H ^○(0) = 55.3 ± 10.6 and D ₀(Sr⁺-OH) = 438.7 ± 10.6 kJ/mol, were interpreted anew. The D ₀(Sr⁺-OH) = 432.8 ± 2.7 kJ/mol value was eventually obtained.     

Cobalt—Sandwiched lindqvist hexaniobate dimer [Co(III)H<Subscript>5</Subscript>(Nb<Subscript>6</Subscript>O<Subscript>19</Subscript>)<Subscript>2</Subscript>]<Superscript>8− 1</Superscript>

A new polyoxoniobate K₆Na₂[Co_IIIH₅(Nb₆O₁₉)₂] · 26.5H₂O (I) has been synthesized by a diffusion strategy and structurally characterized by IR spectrum, UV spectroscopy, TG analysis, and single crystal X-ray diffraction. Compound I crystallizes in the cubic Pa \(\bar 3\) space group with a = 17.969(8)Å V = 5802.6(4) ų, Z = 4, R ₁ = 0.0383 and wR ₂ = 0.1187. Compound I consists of the Lindqvist hexaniobate dimer [Co_IIIH₅(Nb₆O₁₉)₂]^8? in which the Co³⁺ cations sare andwiched between and face-shared with two Lindqvist-type [Nb₆O₁₉]^8? subunits. In situ UV spectra display that compound I can stably exist in an aqueous solution.     

Synthesis and Crystal Structure of [Co(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>](C<Subscript>19</Subscript>H<Subscript>17</Subscript>O<Subscript>4</Subscript>SO<Subscript>3</Subscript>)<Subscript>2</Subscript>⋅8H<Subscript>2</Subscript>O

The title compound, cobalt 4′,7-diethoxylisoflavone-3′-sulfonate([Co(H₂O)₆](X)₂⋅8H₂O, X = C₁₉H₁₇O₄SO₃) was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. It crystallizes in the triclinic space group P-1 with cell parameters a = 9.026(3) Å, b = 16.431(5) Å, c = 18.195(6) Å, α = 72.289(4)^∘, β = 87.498(4)^∘, γ = 82.775(5)^∘, V = 2550.1(13) Å⁻³, D_c = 1.419 Mg m⁻³, and Z = 2. The results show that the title compound consists of one cobalt cation, six coordinated water molecules, eight lattice water molecules, and two 4′,7-diethoxylisoflavone-3′-sulfonate anions, C₁₉H₁₇O₄SO⁻₃. Two anions have different conformations. Twelve H atoms of six coordinated water molecules, as donors, form hydrogen bonds with four oxygen atoms of sulfo-groups of two anions and eight oxygen atoms of eight lattice water molecules. In addition, π < eqid1 > ⋅ < eqid2 > π stacking interactions exist in the crystal structure, which together with hydrogen bonds lead to supramolecular formation with a three-dimensional network.     

Influence of the temperature and cation nature on the EPR spectra of salts with the [Ni<Superscript>III</Superscript>(η<Superscript>5</Superscript>-1,2-B<Subscript>9</Subscript>C<Subscript>2</Subscript>H<Subscript>11</Subscript>)<Subscript>2</Subscript>]- anion

The influence of specific features of the structure and nature of the cations (Ph₄P⁺, H(Phen)⁺, Cs⁺, and (CH₃)₄N⁺) on the ERP spectra of the nickel ions in salts with the dicarbollylnickelate anion [Ni(B₉C₂H₁₁)₂]⁻ is studied. It is shown that the change in the cation type in these compounds results in the electron density redistribution, which affects the change in the main and average values of the g factor. The g _av value increases over that observed in frozen solutions upon the localization of the positive charge of the cation on one atom and in the absence of the screening effect of the solvent and large functional groups of the cation. The exception is the compound (Ph₄P⁺)NiCb₂⁻ (Cb is B₉C₂H₁₁) with solvated CCl₄ molecules. For all compounds studied, the temperature dependence of the linewidths in the EPR spectra is described by the equation ΔH = αT + βT⁷ with different α and β values and is defined by the temperature dependence of the relaxation process caused by the Raman interaction.     

Synthesis and Structure of the bismuth complex [Ph<Subscript>3</Subscript>PrP]<Stack><Subscript>4</Subscript><Superscript>+</Superscript></Stack>[Bi<Subscript>4</Subscript>I<Subscript>16</Subscript>]<Superscript>4−</Superscript>

The complex [Ph₃P] ₄ ⁺ [Bi₄I₁₆]^4? · 2 Me₂C=O (I) was synthesized by the reaction of triphenyl(propyl)phosphonium iodide with bismuth iodide in acetone. The crystal structure of complex I was determined by X-ray crystallography. It contains, in addition to solvent molecules, two types of crystallographically independent tetrahedral tetraphenyl(propyl)phosphonium cations and tetranuclear anions [Bi₄I₁₆]^4? in a chair conformation with the bismuth atoms being in an octahedral coordination. The Bi-I distances in the anion vary within 2.8768(4)–3.2524(4) Å.