theoretical study of tetrahydroborates and alanates L(MH4)4, HL(MH4)3, H2L(MH4)2, and H3L(MH4) (L = Al, Sc, Ti, V, Cr; M = B, Al)

The structural and energetic characteristics of the lowest-lying structures for isolated molecules and ions of light-metal boro- and aluminohydrides L(MH₄)₄, HL(MH₄)₃, H₂L(MH₄)₂, and H₃L(MH₄) (L = Al, Sc, Ti, V, Cr; M = B, Al) with different coordination modes of BH₄⁻- and AlH₄⁻ groups were calculated by the perturbation theory (MP₂), coupled cluster (CCSD(T)), and density functional theory (B3LYP) methods using the 6-31G*, 6-311+G**, and 6-311++G** basis sets. The results are compared with the computational data obtained at the same level of theory for related complexes L(MH₄)₃, HL(MH₄)₂, H₂L(MH₄), L(MH₄)₂, and HL(MH₄). The preferable coordination modes of the ligands in these complexes are analyzed, and the energies of dissociation with elimination of BH₃ (AlH₃) molecules and BH₄⁻ (AlH₄⁻) anions in various series of related hydroborates and hydroaluminates are estimated. The structure and relative stability of classical hydride and (μ-H₂)-hydrogen complexes in the H₂L (MH₄)₂ and H₃L(MH₄) systems are discussed. Original Russian Text ? O.P. Charkin, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 6, pp. 1015–1024.     

Crystal structure of [CuL](NO<Subscript>3</Subscript>)(ReO<Subscript>4</Subscript>) and [CuL](ReO<Subscript>4</Subscript>)<Subscript>2</Subscript> (L = 4,6,6-trimethyl-1,9-diamino-3,7-diazanon-3-en)

The crystal structures of [CuL](NO₃)(ReO₄) and [CuL](ReO₄)₂ (L is 4,6,6-trimethyl-1,9-diamino-3,7-diazanon-3-en) are studied. The square coordination of the copper atom in [CuL](NO₃)(ReO₄) is completed to a distorted octahedron by two oxygen atoms: Cu…O (ReO ₄ ^? ) 2.393 Å and Cu…O (NO ₃ ^? ) 2.685 Å, and that in [CuL](ReO₄)₂, by Cu…O(ReO ₄ ^? ) 2.468 Å and 2.697 Å. The products of thermolysis of the salts in a hydrogen atmosphere at 800°C are mixtures of nanocrystalline metal powders with coherent scattering regions of ～45 nm.     

Phase transitions in double molybdates K<Subscript>2</Subscript>M<Stack><Subscript>2</Subscript><Superscript>II</Superscript></Stack>(MoO<Subscript>4</Subscript>)<Subscript>3</Subscript> with M = Mg or Co

Phase transitions and cation mobility in double molybdates K₂M ₂ ^II (MoO₄)₃ with M = Mg or Co and the products of their heterovalent doping with scandium(III) and vanadium(V) have been studied. The transition from low to high conductivity in K₂M ₂ ^II (MoO₄)₃ is the result of a two-stage phase transition, whose occurrence is significantly extended in time. Heterovalent substitutions noticeably decrease the heat of the phase transition. The transition to the low-temperature phase is not achieved even after long-term exposure.     

Geometric and spectral characteristic of the tetrahalocuprate(II) complexes (HL)<Subscript>2</Subscript>CuX<Subscript>4</Subscript> (X = Cl,Br). Crystal and molecular structures of bis(2-methylimidazolium) tetrabromocuprate(II)

The crystal and molecular structures of bis(2-methylimidazolium) tetrabromocuprate(II) are determined. The linear dependences of the degree of distortion of the CuBr ₄ ^2? coordination polyhedron on the protonation constant of the organic cation are revealed for the structures with θ < 140°. The dependence of the hydrogen bond parameters (distances H…Br and N…Br, angle NHBr) on the degree of distortion of CuBr ₄ ^2? is shown. The degree of distortion of CuX ₄ ^2? (X = Cl, Br) is determined by the type of the organic cation and is almost the same for the CuBr ₄ ^2? and CuCl ₄ ^2? polyhedra. The empirical equations relating the degree of distortion of CuX ₄ ^2? (X = Cl, Br) and the position of the Cu ← X ligand-to-metal charge-transfer band (νLMCT) are obtained.     

Synthesis and structure of [UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>){CONH<Subscript>2</Subscript>N(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>}<Subscript>2</Subscript>]

The single crystals of [UO₂(C₂O₄){CONH₂N(CH₃)₂}₂] were synthesized and studied by X-ray diffraction. The crystals are monoclinic, a = 7.461(2) Å, b = 8.828(2) Å, c = 11.756(2) Å, β = 107.21(3)°, space group Pc, Z = 2, R = 2.94%. The structure comprises infinite chains [UO₂(C₂O₄){CONH₂N(CH₃)₂}₂] extended along [001] and corresponding to the AT¹¹M ₂ ¹ crystallochemical group (A = UO ₂ ²⁺ , T¹¹ = C₂O ₄ ^2? , M¹ = N,N-CONH₂N(CH₃)₂) of uranyl complexes. The chains are connected into a three-dimensional framework by hydrogen bonds involving the oxygen atoms of oxalate and uranyl ions and the N,N-dimethylcarbamide methyl groups.     

Thermal properties,phase transitions,vibrational and reorientational dynamics of [Mn(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

[Mn(NH₃)₆](NO₃)₂ crystallizes in the cubic, fluorite (C1) type crystal lattice structure (Fm \( \overline{3} \) m) with a = 11.0056 Å and Z = 4. Two phase transitions of the first-order type were detected. The first registered on DSC curves as a large anomaly at T _C1 ^h  = 207.8 K and T _C1 ^c  = 207.2 K, and the second registered as a smaller anomaly at T _C2 ^h  = 184.4 K and T _C2 ^c  = 160.8 K (where the upper indexes h and c denote heating and cooling of the sample, respectively). The temperature dependence of the full width at half maximum of the band associated with the δ_s(HNH)F_1u mode suggests that the NH₃ ligands in the high temperature and intermediate phase reorientate quickly with correlation times in the order of several picoseconds and with activation energy of 9.9 kJ mol^?1. In the phase transition at T _C2 ^c probably only a some of the NH₃ ligands stop their reorientation, while the remainders continue to reorientate quickly with activation energy of 7.7 kJ mol^?1. Thermal decomposition of the investigated compound starts at 305 K and continues up to 525 K in four main stages (I–IV). In stage I, ²/₆ of all NH₃ ligands were seceded. Stages II and III are connected with an abruption of the next ²/₆ and ¹/₆ of total NH₃, respectively, and [Mn(NH₃)](NO₃)₂ is formed. The last molecule of NH₃ per formula unit is freed at stage IV together with the simultaneous thermal decomposition of the resulting Mn(NO₃)₂ leading to the formation of gaseous products (O₂, H₂O, N₂ and nitrogen oxides) and solid MnO₂.     

Crystal Structure of [UO<Subscript>2</Subscript>SO<Subscript>4</Subscript>{(CH<Subscript>3</Subscript>)HNCONH(CH<Subscript>3</Subscript>)}<Subscript>2</Subscript>]

The single crystals of [UO₂SO₄{(CH₃)HNCONH(CH₃)}₂] (I) were synthesized and studied by X-ray diffraction. The crystals are monoclinic, a = 6.847(1) Å, b = 14.259(3) Å, c = 14.297(3) Å, β = 93.451(4)°, space group P2₁/n, Z = 4. The main structural units of crystals I are ribbons whose composition coincides with the composition of the compound. The crystal chemical formula of the complex is AT³M ₂ ¹ (A = UO ₂ ²⁺ ).     

Synthesis,crystal structure,and vibrational spectra of M<Subscript>4</Subscript>V<Subscript>2</Subscript>O<Subscript>3</Subscript>(SO<Subscript>4</Subscript>)<Subscript>4</Subscript> (M = K,Rb, Cs)

Synthesis was performed and physicochemical properties were studied for the M₄V₂O₃(SO₄)₄ complexes, where M = K, Rb, or Cs. Their crystal structures were determined using the set of data from X-ray diffraction and neutron diffraction studies. All compounds crystallize in a triclinic lattice (space group \(P\bar 1\), Z = 2) with the parameters: a = 7.7688(2), 7.8487(1), 8.1234(1) Å; b = 10.4918(3), 10.8750(2), 11.1065(1) Å; c = 11.9783(4), 12.1336(2), and 11.8039(1) Å; α = 76.600(2)°, 77.910(1)°, 79.589(1)°; β = 75.133(2)°, 75.718(1)°, 87.939(1)°; γ = 71.285(2)°, 72.189(1)°, 75.567(1)°; V = 881.78(5), 945.42(3), 1014.34(2) ų for K, Rb, Cs, respectively. The structure of M₄V₂O₃(SO₄)₄ was found to be formed by discrete complex anions V₂O₃(SO₄) ₄ ^4? incorporating two oxygen-bridged vanadium atoms in a distorted octahedral oxygen environment. The sulfate groups are coordinated by the vanadium atoms in the chelating mode with a large scatter of S-O interatomic distances and OSO angles. Every VO₆ octahedron has a short terminal vanadium-oxygen bond with a length of about 1.6Å. The V₂O₃(SO₄) ₄ ^4? complex anions in potassium and rubidium compounds differ from that in Cs₄V₂O₃(SO₄)₄ in the type of symmetry and mutual spatial orientation. The vibrational spectra were presented and interpreted in line with the structural analysis data.     

Chemistry of the CARBEX process: Identification of absorption bands of the ligands in the electronic spectra of aqueous solutions of Na<Subscript>4</Subscript>[UO<Subscript>2</Subscript>(O<Subscript>2</Subscript>)CO<Subscript>3</Subscript>)<Subscript>2</Subscript>]

On the basis of consideration of dissociation, hydration, association, and ligand exchange, the assignment of absorption bands in the electronic spectra of aqueous solutions of the Na₄[UO₂(O₂)CO₃)₂] complex has been performed. It has been demonstrated that the absorption in the range 190–400 nm is caused by the oxygen atoms of the O₂^2- and CO₃^2- groups and hydration water molecules of dissociated and neutral complex species Na₃[UO₂(O₂)(CO₃)₂]^–, Na₂[UO₂(O₂)(CO₃)₂]^2–, and Na₄[UO₂(O₂)(CO₃)₂].     

Structure and some properties of [UO<Subscript>2</Subscript>CrO<Subscript>4</Subscript>{CH<Subscript>3</Subscript>CON(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>}<Subscript>2</Subscript>]

A new complex [UO₂CrO₄{CH₃CON(CH₃)₂}₂] (I) was studied by thermal analysis, IR spectroscopy, and X-ray crystallography. The crystals are monoclinic: a = 13.8108(11) Å, b = 8.6804(7) Å, c = 13.0989(10) Å, β = 104.777(1)°, V = 1518.4(2) ų, space group P2₁/c, Z = 4, R = 2.39%. The structure of I contains infinite chains of the [UO₂CrO₄{CH₃CON(CH₃)₂}₂] composition running along [001]; the complex belongs to the AT¹¹M¹ ₂ crystal-chemical group (A = UO ₂ ²⁺ , T¹¹ = CrO ₄ ^2? , M¹ = CH₃CON(CH₃)₂) of uranyl complexes. The chains are linked into a three-dimensional framework due to hydrogen bonds between oxygen atoms of chromate ions and hydrogen atoms of methyl groups of the dimethylacetamide.     

Crystal and molecular structure of ammonium trinitratouranylate NH<Subscript>4</Subscript>[UO<Subscript>2</Subscript>(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>]

Ammonium trinitratouranylate NH₄[UO₂(NO₃)₃] (I) single crystals have been synthesized by the reaction of aqueous solutions of diaquadinitratouranyl tetrahydrate and ammonium nitrate in the presence of nitric acid. The structure of the complex has been studied by X-ray diffraction analysis: space group \(R\bar 3c\), a = 9.361(2), c = 18.883(4) Å; V = 1433.0(5) ų, and Z = 6. The structural units of the NH₄[UO₂(NO₃)₃] crystal—NH ₄ ⁺ cations and [UO₂(NO₃)₃]^? complex anions with three bidentate cyclic nitrato groups—are on crystallographic axes \(\bar 3\). A complex three-dimensional packing arranged by the electrostatic attraction forces between counterions and the N-H...O hydrogen bonds between ammonium cations and trinitratouranylate anions is realized in the structure. X-ray diffraction analysis results are confirmed by IR spectra of NH₄[UO₂(NO₃)₃].     

Complex amidoboranes M<Superscript>2</Superscript>[M<Superscript>1</Superscript>(NH<Subscript>2</Subscript>BH<Subscript>3</Subscript>)<Subscript>4</Subscript>] (M<Superscript>1</Superscript> = Al,Ga; M<Superscript>2</Superscript> = Li,Na, K,Rb, Cs)

Structural, spectral, and thermodynamic characteristics of complex amidoboranes M²[M¹(NH₂BH₃)₄] (M¹ = Al, Ga; M² = Li, Na, K, Rb, Cs) were calculated by the B3LYP/def2-SVPD quantum-chemical method. The procedure for the synthesis of these compounds by reactions of alkali metal amidoboranes with aluminum and gallium chlorides was suggested and experimentally tested. Reaction products were characterized by the NMR and IR spectroscopy and X-ray phase analysis.     

Structure and some properties of [UO<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)(C<Subscript>5</Subscript>H<Subscript>12</Subscript>N<Subscript>2</Subscript>O)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)]

The complex [UO₂(SeO₄)(C₅H₁₂N₂O)₂(H₂O)] (I) was synthesized and studied by thermal analysis, IR spectroscopy, and X-ray crystallography. The crystals are orthorhombic: a = 13.1661(3) Å, b = 16.4420(5) Å, c = 17.4548(6) Å, Pbca, Z = 8, R = 0.0423. The structural units of crystal I are chains with the composition coinciding with that of the compounds of the AB₂M ₃ ¹ crystal chemical group of the uranyl complexes (A = UO ₂ ²⁺ , B² = SeO ₄ ^2? , M¹ = C₅H₁₂N₂O and H₂O).     

Synthesis,structures, IR spectra,and thermal characteristics of compounds of general formula Ba(M<Stack><Subscript>2/3</Subscript><Superscript>III</Superscript></Stack>U<Subscript>1/3</Subscript>)O<Subscript>3</Subscript> (M<Superscript>III</Superscript> = Sc,Y, In,Nd-Lu)

Compounds with the composition Ba(M _2/3 ^III U_1/3)O₃ (M^III = Sc, Y, In, Nd-Lu) were synthesized by high-temperature solid-state reactions. The structures of the compounds were studied by X-ray diffraction analysis, including the high-temperature method, and IR spectroscopy.     

Crystal structure of [Bi(<Emphasis Type="Italic">N</Emphasis>-ethylthiourea)<Subscript>4</Subscript>(ClO<Subscript>4</Subscript>)<Subscript>2</Subscript>]ClO<Subscript>4</Subscript>

The structure of the bismuth(III) complex with N-ethylthiourea (Ettu) has been determined for the first time. We found that the crystal structure of [Bi(Ettu)₄(ClO₄)₂]ClO₄ is built of distorted octahedral cations [Bi(Ettu–S)₄(ClO₄)₂]ClO₄]⁺ and anions ClO₄^-. The deviation of one of the two independent Ettu molecules from the plane structure is explained by the mutual repulsion of the ligands and the formation features of hydrogen bonds. The C₂H₅(Ettu) group is in the cis position relative to the thiocarbonyl group.     

Synthesis,structure, physicochemical properties,and solid-phase thermolysis of Co<Subscript>2</Subscript>Sm(Piv)<Subscript>7</Subscript>(2,4-Lut)<Subscript>2</Subscript>

Heterometallic pivalate Co₂Sm(Piv)₇(2,4-Lut)₂ (1) was prepared for the first time and structurally characterized at 293 and 160 K. Antiferromagnetic exchange interactions are dominant in complex 1. This compound experiences a first-order phase transition within 210–260 K. A set of thermodynamic functions was obtained for this complex (C _p , H _T ⁰ - H ₁₈₀ ⁰ , and S _T ⁰ ), and parameters were determined for solid-phase thermolysis where samarium cobaltate SmCoO₃ is the only product.     

Crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH<Subscript>2</Subscript>NHC(O)NH<Subscript>2</Subscript>)<Subscript>2</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

The crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH₂NHC(O)NH₂)₂](NO₃)₂ has been studied by X-ray diffraction. Monoclinic crystals, a = 6.835(2) Å, b = 7.733(2) Å, c = 10.320(3) Å, β = 105.701(3)°, V = 525.1(2) ų, space group P2₁/c, Z = 2, d _msd = 2.136 g/cm³, μ(MoK _α) = 2.143 mm⁻¹. The structure was solved with the program for automatic analysis of Patterson’s function and refined by full-matrix least squares in an anisotropic approximation for all non-hydrogen atoms using 753 independent reflections; R ₁ = 0.0203. The square environment of the Cu atom is formed from the amino nitrogen atoms of the hydrazine fragments and the C=O oxygen atoms of the two semicarbazide bidentate molecules (Cu-N 1.928 Å, Cu-O 1.999 Å). The axial positions are occupied by the O atoms of the NO ₃ ⁻ outer-spheric anions (Cu-O 2.505 Å). In the structure, the complex cations and the NO ₃ ⁻ anions are linked into a framework by N-H...O type hydrogen bonds. Original Russian Text Copyright ? 2007 by G. V. Romanenko, Z. A. Savelieva, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 370–373, March–April, 2007.     

New ruthenocene-based ruthenium pincer complex bearing the C<Subscript>5</Subscript>Me<Subscript>4</Subscript>CF<Subscript>3</Subscript> ligand

The first (trifluoromethyl)tetramethylruthenocene-based ruthenium pincer complex RuCl(CO)[{2,5-(Bu ₂ ^t PCH₂)₂C₅H₂}Ru(C₅Me₄CF₃)] was synthesized by cyclometallation of the bisphosphine ligand {1,3-(Bu ₂ ^t PCH₂)₂C₅H₂}Ru(C₅Me₄CF₃) with RuCl₂(DMSO)₄ in 2-methoxyethanol in the presence of NEt₃. The new complex was fully characterized by ¹H, ¹⁹F, ³¹P{¹H}, ¹³C{¹H} NMR and IR spectroscopy.     

Synthesis of dugganite Pb<Subscript>3</Subscript>TeZn<Subscript>3</Subscript>As<Subscript>2</Subscript>O<Subscript>14</Subscript> and its analogues

A ₃ ²⁺ Te⁶⁺M ₃ ²⁺ X ₂ ⁵⁺ O₁₄ (A = Pb, Ba, Sr; M = Zn, Mg, Co, Mn, Cu, Cd; X = P, As, V) compounds and Pb₃WZn₃P₂O₁₄, all with Ca₃Ga₂Ge₄O₁₄ structure (space group P321), were prepared by solid-phase synthesis in air at 600–1000°C. Most compounds melt incongruently or experience solid-phase decomposition.     

Synthesis and Properties of Double Complex Salts Containing the Cation [Co(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>]<Superscript>3+</Superscript>

A series of complexes [Co(NH₃)₆] _x [ML₆₍₄₎] _y , where M is Fe(III) and Fe(II), Cr(III), Cu(II); L is CN^?, NCS^?, 1/2C₂O ₄ ^2? , are synthesized. Their IR spectra and thermal decomposition in air are studied, and interplanar distances in crystalline lattices of the complexes are determined. The compounds can be used as precursors for producing homogeneous bimetallic nanodimensional powders.