Synthesis and crystal structure of bis (2-phenylethylammonium) dihydrogendimphosphate, [C6H5(CH2)2NH3]2H2P2O7

Chemical preparation, crystal structure and infrared absorption spectra are given for a new organic cation dihydrogendiphosphate. The new synthesized compound [C₆H₅(CH₂)₂NH₃]₂H₂P₂O₇; crystallized in the monoclinic system (P2_1/c space group) with Z = 4 and with the following unit-cell dimensions: a = 19.006(3); b = 10.718(2), c = 10.996(3) Å and β = 98.99(2) °. Its crystal structure was determined and refined down to R = 0,056 by using 3278 independent reflections. As in all atomic arrangements including acidic diphosphate groups; we can observe the formation of an infinite network of anions connected by strong H-bonds.     

Optical spectroscopy of (C2H5NH3)2CdCl4:Cu2+ under pressure: Study of Cu2+ local structure from theoretical calculations

The variations experienced by the energy E_u(π) of the e_u(π)→b_1g (～x²–y²) charge‐transfer transition of (C₂H₅NH₃)₂CdCl₄:Cu²⁺ upon pressure in the 0‐ to 40‐kbar range have been measured at room temperature by means of a sapphire anvil cell. These data reveal that E_u(π) undergoes a red shift of 1400 cm^?1 on passing from ambient pressure to 40 kbars. To understand this puzzling result theoretical calculations of ?E_u(π)/?R_eq and ?E_u(π)/?R_ax have been performed where R_eq and R_ax mean the equatorial and axial Cu²⁺–Cl^? distances of the elongated CuCl₆^4? complex, respectively. All results indicate that ?E_u(π)/?R_eq and ?E_u(π)/?R_ax for R_eq=228 pm and R_ax=297 pm are indeed negative. Moreover ab initio complete active space self‐consistent field (CASSCF/CASPT2) and density functional calculations lead to ?E_u(π)/?R_ax values, which are about 10 times smaller than those of ?E_u(π)/?R_eq. From the ensemble of experimental and theoretical results, it is concluded that a pressure of 40 kbars gives rise to a decrement of ≈25 pm of the axial distance and at the same time to an increase of ≈7 pm of the equatorial one. It is stressed that the present study on a diluted Jahn–Teller impurity lies far beyond the current possibilities of X‐ray absorption structure techniques. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

Infrared studies of phase transitions in ferroelectric (C5H5NH)5Bi2Br11

Infrared spectra (3500–500 cm⁻¹) of polycrystalline (C₅H₅NH)₅Bi₂Br₁₁ samples were investigated within the temperature range 27–456 K. The assignments of the observed bands in the spectra measured at 27, 310 and 456 K are proposed. A temperature dependence of the wavenumbers and full width at half maximum (FWHM) of the bands arising from some internal vibrations of pyridinium cations are analysed in order to explain the role of cations in the mechanism of the phase transition at 118 (paraelectric–ferroelectric) and 403 K. It was found that numerous bands arising from the internal modes of the cations exhibit the splitting in the vicinity of both phase transitions, that indicates a distinct changes in the motional state of the pyridinium moieties.     

Preparative and Structural Studies of Halodimolybdates (II). II Preparation of (NH4)4Mo2Br8, (NH4)5Mo2Br9 · H2O,Rb5Mo2Cl9 · H2O and Crystal Structure of (NH4)4Mo2Br8

Iron(III) Complexes with Ethylene Diamine Tetraacetic Acid or Nitrilotriacetic Acid and Phenol Quarternary complexes of iron(III) with phenol (HR) and ethylene diamine tetraacetic acid (H₄Y) as well as nitrilotriacetic acid (H₃X) in aqueous solution could be detected. The equilibria have been controlled by spectrophotometric and electrophoretic methods. The measured optical properties and the equilibrium constants are discussed. The following particles are present : (see ?Inhaltsübersicht”?)     

Molecular and crystal structure of Bis(η5-cyclopentadienyl)titanium(IV) Dibromide,Ti(η5-C5H5)2Br2

The crystal and molecular structure of Bis(η⁵-cyclopentadienyl)titanium(IV) dibromide, Ti(η⁵?C₅H₅)₂Br₂, has been investigated by an X-ray structure determination. Crystal data: triclinic, a = 7.872(5), b = 11.807(5), c = 12.310(3) Å, α = 107.62(3), β = 100.83(4), γ = 90.69(4)°, V = 1 068(14) ų, T = 293, space group P1 , Z = 4 (there are two crystallographically independent molecules in the asymmetric unit cell and their conformations are similar). Final R and R_w values are 0.068 and 0.073, respectively. The structural results are compared to those for similar type molecules.     

The electronic structure of the B2H 5 + ion

The B₂H ₅ ⁺ ion has been studied using theab initio SCF method employing a basis set of Gaussian orbitals and various semi-empirical methods. The most stable structure appears to be a planar structure with two vacantp orbitals rather than a triply bridged structure suggested by analogy with acetylene with which it is isoelectronic. The semi-empirical results reinforce earlier conclusions that inclusion of charges from neighbouring atoms in iterative Extended Hückel methods is necessary to satisfactorily treat ionic molecules.

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Zusammenfassung Das B₂H ₅ ⁺ -Ion ist mit Hilfe derab initio SCF-Methode unter Benutzung eines Basissatzes von Gaußorbitalen und mit verschiedenen semiempirischen Methoden untersucht worden. Die stabilste Struktur scheint eine planare Struktur mit zwei leerenp-Orbitalen und nicht eine dreifach verbrückte Struktur zu sein, wie sie durch Analogiebetrachtungen am Acetylen nahegelegt wird. Durch die semiempirischen Resultate werden die bereits früher erhaltenen Ergebnisse bestätigt, daß zur zufriedenstellenden Behandlung von Molekülionen mit iterativen erweiterten Hückel-Methoden die Berücksichtigung der Ladungen benachbarter Atome nötig ist.

     

Unique Isle Anion [Cu6Cl10]4- in π-Complex of Cu(I) Chloride with 1-(2-Pyridyl)-4-allyl-piperazinium. Synthesis and crystal structure of [(C5H4NH)NC4H8NH(C3H5]2+[Cu3Cl5]2-

Single crystals of [(C₅H₄NH)NC₄H₈NH(C₃H₅)]²⁺[Cu₃Cl₅]^2? are obtained by ac synthesis in ethanol from 1-(2-pyridyl)-4-allyl-piperazinium and Cu(II) dichlorides and their structure is studied by X-ray diffraction analysis (space group P-1, a = 7.246(7) Å, b = 8.54(1) Å, c = 16.41(1) Å, α = 70.76(8)°, β = 77.24(8)°, λ = 80.42(9)°, V = 30(4) ų, Z = 2, R(F) = 0.0686. In the structure of this π-complex, the Cu and Cl atoms form unusual centrosymmetrical Cu₆Cl₁₀ fragments, each fragment being bonded to two 1-(2-pyridyl)-4-allyl-piper-azinium cations via π-interaction Cu-(C=C). A three-dimensional structure is formed by means of N-H…Cl hydrogen bonds. The trigonal-pyramidal surrounding of the Cu(1) atom includes three Cl atoms and the C=C bond, while the tetrahedral surrounding of Cu(2) and the trigonal surrounding of Cu(3) involve the Cl atoms only.     

The Crystal Structure of Binuclear Metal Complexes of 7-Azaindole: Cu2 (CH3CO2)2 (C7H5N2)2(C7H6N2)2 AND Ni2(C7H5N2)4.2DMF

The crystal and molecular structures have been determined by single-crystal X-ray methods for the binuclear metal ions (II) complexes of 7-azaindole (1H-pyrrolo [2,3-b] pyridine, C₇H₆N₂ denoted by HL), Cu₂(CH₃CO₂)₂.·L₂(HL)₂ and Ni₂L₄.2DMF. The dark green crystal of Cu₂(CH₃CO₂)₂L₂(HL)₂ was found to crystallize in the monoclinic space group P 2₁/n with a = 9.566(2), b = 12.752(2), c = 12.852(4) Å, β = 99.23(3)⁰, V = 1547 Å, Z = 2, the final R = 0.062 and Rw = 0.053 for 1488 observations from 2722 unique reflections. The Cu-Cu distance is 2.747(2), Cu-N (L^?, bridge) is 1.966(7), Cu-N (HL, axial) is 2.229(8), and Cu-O is 2.031(6)Å. The red crystal of Ni₂L₄.2DMF was was found to crystallize in the triclinic space group \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm P \bar 1} $$\end{document} with a = 8.907(5), b = 9.462(2), c = 10.217(2) Å, α = 90.48(2), β = 91.09(3), γ = 110.69(3)⁰, V =805 ų, Z = 1, the final R = 0.063 and Rw = 0.069 for 1489 observations from 2834 unique reflections. The Ni-Ni distance is 2.594(2), Ni-N is 1.905(7) Å. These two molecules lie on crystllographic inversion centers and exhibit ligand disorder.     

(C4H3SCH2NH3)2(CH3NH3)Pb2I7: non-centrosymmetrical crystal structure of a bilayer hybrid perovskite

The analysis of the crystal structure of (C4H3SCH2NH3)2(CH3NH3)Pb2I7, displaying a well-ordered acentric inorganic Pb2I7(3-) bilayer, is reported, and compared to the related monolayer hybrid perovskite.     

Thermal transformations of B10H12(NH3)2, B10H12(C5H5N)2, and B10H12(C9H7N)2

Conclusions For B₁₀H₁₂L₂, where L=NH₃, C₅H₅N, or C₉H₇N, features of thermal transformations in the range 25–850°C and the composition of the pyrolysis products are determined. The latter are x-ray amorphous phases, containing nitride, carbide, boron carbide, boron, and carbon.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2481–2484, November, 1988.     

Copper(I) Complexes with N-Allylquinolinium Bromide [C9H7N(C3H5)]CuBr2 and [C9H7N(C3H5)]Cu2Br3: Synthesis and Crystal Structure

Crystals of [₉₇N(₃₅)]uBr₂ (IV) and [₉₇N(₃₅)][u₂Br₃] (V) were prepared by ac electrochemical synthesis from uBr₂, N-allylquinolinium bromide, on copper electrodes in the ethanol–benzene medium. X-ray diffraction study has shown that crystals IV and V are monoclinic: space group A2₁/a, a = 13.776(3) Å, b = 14.304(3) Å, c = 13.147(2) Å, = 107.90(1) Å, V = 2465(2) ų, Z = 8 for IV and space group P2₁/n, a = 13.881(2) Å, b = 15.446(2) Å, c = 7.111(1) Å, = 104.64(1)°, V = 1475.0(8) ų, Z = 4 for V. Structures IV and V are built of the N-allylquinolinium cations and different anions i.e., (CuBr₂) ^n- _n forming infinite chains in IV and peculiar {[Cu^I ₄Br₆]^2–} _n arranged in polymeric chains in V. In the latter case, two independent metal atoms have trigonal–pyramidal and trigonal–planar environments. In the structures of both compounds, the C=C bond of the allyl group is not involved in coordination with the Cu(I) atom.     

Crystal and molecular structure of complex compound (C5H5)2Re(H)Cu(μ-I)2CuRe(H)(C5H5)2: A first direct proof of the formation of the Cu(I)Cu(I) bond

The structure of the bimetallic dimer complex [(η⁵-C₅H₅)₂Re(H)CuI]₂ has been investigated. The crystals are monoclinic: a = 16.070(4) Å, b = 7.788(2)Å, c = 17.439(5) Å; b = 96.62(2)°; the space group I2/a; z = 4. The bond between rhenium and copper atoms (2.60 Å) is of the donor-acceptor type; dimerization occurs by the way of formation of the double bridge CuI₂Cu and the direct inter-metal bond CuCu(2.55 Å). The hydride hydrogen atom is the terminal one. The cyclopentadienyl rings form a bent sandwich with the angle between the ring centres and rhenium atom being equal to 158°. It is suggested that the CuCu inter-metal bonding takes place on account of the transition of the non-bonding d-electrons of copper atoms to a high-spin state.     

Syntheses of(C_8H_8)Ln(C_9H_7)·(THF)_2(Ln=Pr,Nd)and crystal structure of(C_8H_8)Pr(C_9H_7)·(THF)_2

This paper reports two lanthanide complexes of formula (C_9H_7)Ln(C_8H_8)·(THF)_2 whereLn is Pr or Nd,C_9H_7 is indenyl,and C_8H_8 is cyclooctatetraene (COT).The complexes were preparedby the reaction of LnCl_3 with K(C_9H_7) and K_2(C_8H_8) in THF.(C_9H_7)Pr(C_8H_8)·(THF)_2 crystallizes inTHF at - 15℃ in the monoclinic space group P2_1:with unit cell dimensions a=8.446(0),b=10.083(2),c=13.407(3),β=105.48(1)°,V=1100.43(35)~3,Dc=1.52g/cm~3 and Z=2.The final R valueis 0.033,R_w value is 0.030,respectively.In (C_9H_7)Pr(C_8H_8)·(THF)_2 a five-membered ring centroid ofC_9H_7,the C_8H_8 ring centroid and the two oxygen atoms from the two THF molecules form a distortedtetrahedral geometry around the metal.