Molecular structure of AlH3[N(CH2CH2)3CH]2

Reaction of AlH₃[N(CH₂CH₂)₃CH] with hexamethyltrisiloxane, (OSiMe₂)₃, gives rise to the bis-quinuclidine complex AlH₃[N(CH₂CH₂)₃CH]₂, which has been characterized by ¹H and ¹³C NMR spectroscopy and X-ray crystallography. The molecular structure of AlH₃[N(CH₂CH₂)₃CH]₂ consists of a trigonal bipyramidal aluminum with axial coordination of the quinuclidine ligands. Crystal data: orthorhombic, space group Pbcn, a = 10.6895(9), b = 12.266(1), c = 12.3794(9) Å, V = 1623.2(2) ų, and Z = 4.     

Polarization switching in (CH3NH3)5Bi2Cl11 ferroelectric crystals

The polarization switching in methylammonium chlorobismuthate, (CH₃NH₃)₅Bi₂Cl₁₁, single crystal was investigated by optical observations of the domain structure and switching current registration. It is shown that defects introduced during crystal growth influence the polarization switching kinetics. For the analysis of switching current data the statistical Avrami model of phase transformation kinetics was employed. Direct observation of the domain structure enabled us to verify the assumptions of the Avrami model in the case of non‐uniform (CH₃NH₃)₅Bi₂Cl₁₁ crystals. It is found that application of this model to non‐uniform crystals can yield physically unclear values of some fitting parameters; e.g. the effective domain growth dimension is not constant with respect to the electric field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The structures of three trimethylarsine-boron trihalide adducts: (CH3)3AsBCl3, (CH3)3AsBBr3, and (CH3)3AsBI3

An X-ray structure analysis of three trimethylarsine-boron trihalide adducts has been undertaken. Crystals of (CH₃)₃AsBCl₃ and (CH₃)₃AsBBr₃ are monoclinic with space groupP2₁/m (No. 11) withZ=2 while those of (CH₃)₃AsBI₃ are orthorhombic with space groupPnma (No. 62) withZ=4. For (CH₃)₃AsBCl₃,a=6.497(3) Å,b=10.735(3) Å,c=7.070(2) Å,=111.8(3)°,V=458.4(3) ų,R=0.0343. For (CH₃)₃AsBBr₃,a=6.672(4) Å,b=11.135(7) Å,c=7.199(4) Å,=111.5(1)°,V=497.7(5) ų,R=0.0434. For (CH₃)₃ÅsBI₃,a=13.113(7) Å,b=11.733(5) Å,c=7.387(3) Å,V=1136.5(5) ų,R=0.0329. The As-B bond lengths are 2.065(6), 2.04(1), and 2.03(1) Å, respectively, for the chloride, bromide, and iodide. These and other structural parameters are discussed with reference to previous predictions based on vibrational spectra and previous structural studies on the trimethyl-phosphine and trimethylamine adducts.     

Synthesis and molecular structure of {[Se(CH3)3][(CH3)AlCl3]}n: A novel two-dimensional layered organoaluminum-selenium polymer

The crystalline product {[Se(CH₃)₃][(CH₃)AlCl₃]}_n was prepared from reaction of SeCl₄ with A1(CH₃)₃ in heptane. The organo-main group polymer crystallizes in the monoclinic space group P2₁/c with unit cell parametersa=11.218(3) Å,b=11.119(3) Å,c=9.915(2) Å,=107.82(2)°,V=1177.4(5) ų, andD ^calcd=1.54 g cm^–3 forZ=4. Least-squares refinement based on 1195 observed reflections I>3(I) in the range 3.50°<2<45.0° led to a finalR factor of 0.036 (R ^w=0.047). The asymmetric unit contains one selenonium ion, Se(CH₃) ₃ ⁺ , and one organoaluminum anionic species, (CH₃)AlCl ₃ ^– . Secondary interactions (SeCl) serve to link the ions along two dimensions to form infinite layers. Thus, {[Se(CH₃)₃] [(CH₃)A1C1₃]}_n may be regarded as a layered organoaluminum-selenium polymer. The mean Se-C bond distance is 1.921(5) Å while the mean C-Se-C bond angle is 99.1(4)°. The independent Al-C bond distance is 1.927(8) Å while the mean Al-Cl bond distance is 2.166(7) Å.     

Synthesis,Crystal Growth,Structural and Physical Properties of bis(thallium) bis(nitrilotriacetato) zirconate dihydrate,Tl2Zr(N[CH2COO]3)2 · 2H2O

Single crystals of Tl₂Zr(N[CH₂COO]₃)₂ · 2H₂O having optical quality and dimensions up to 30 × 25 × 12 mm have been grown from aqueous solutions by controlled lowering of temperature. The raw material was synthesized as the first fraction of crystallization during evaporation of an aqueous solution of (CH₃NH₃)₂Zr(N[CH₂COO]₃)₂ · 2H₂O and TlNH₂SO₃. A crystal structure analysis revealed an isotypy to the K₂Zr(N[CH₂COO]₃)₂ · 2H₂O family, space group Ccc2, a₁ = 14.780(2)Å, a₂ = 14.933(2)Å, a₃ = 8.901(1)Å, Z = 4, ρ_calc. = 3.145 gcm^‐3. Thermal stability, thermal expansion and pyroelectric, dielectric, piezoelectric, elastic and thermoelastic properties have been determined. All properties are closely related to those of Rb₂Zr(N[CH₂COO]₃)₂ · 2H₂O.     

Size effects in [N(CH3)4]2Zn0.58Cu0.42Cl4 crystals

The temperature dependences of birefringence in thin [N(CH₃)₄]₂Zn_0.58Cu_0.42Cl₄ crystals in the thickness range 20 × 10^?6 ≤ d ≤ 500 ? 10^?6 m have been investigated. An increase in the temperatures of the parent phase-incommensurate phase and incommensurate phase-ferroelectric phase transitions has been found. The reasons for the shift in the phase transition temperatures with a decrease in the thickness of [N(CH₃)₄]₂Zn_0.58Cu_0.42Cl₄ crystal and the size effect in crystals with an incommensurate superstructure are discussed.     

Crystal structure and phase transition in the compound [C6H5CH2NH(CH3)2]TlCl4

The N‐N dimethyl benzylammonium tetrachlorothallate (III) [C₆H₅CH₂NH(CH₃)₂]TlCl₄ crystallizes in the monoclinic system P2₁/n at room temperature with the following unit cell dimensions: a = 7.725(3) Å, b = 14.080(5) Å, c = 13.697(4) Å, β = 91.2(2)° with Z = 4. The structure shows a layer arrangement perpendicular to the b axis: planes of [TlCl₄]^‐ tetrahedra alternate with planes of [C₆H₅CH₂NH(CH₃)₂]⁺ cations. The cohesion of the atomic arrangement is ensured by hydrogen bonds N‐H…Cl. Differential scanning calorimetric and optical birefringence measurements reveals a phase transition at T = 339K. Raman spectroscopic study and dielectric measurements were performed to discuss the mechanism of the phase transition. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Organometallic vapour phase epitaxy of galliumarsenide using Ga(CH3)3 · N(CH3)3-adduct as precursor

Epitaxial layers of GaAs have been grown by MOVPE using trimethylgallium-trimethylamin-adduct (TMGa-TMN) as the Ga-precursor. In comparison to the growth system using pure TMGa no significant influence on growth conditions and materials parameters could be found. The deposited GaAs is of fairly high quality with room temperature mobilities of 6700 cm²/Vs at free electron concentrations of about 1 × 10¹⁵ cm⁻³. No hints to nitrogen incorporation could be found.     

Spectra and structure of organophosphorus compounds,XVIII: Infrared and Raman spectra of [(CH3)2PS]2, [(CD3)2PS]2, and [(CH3CH2)2PS]2 in the solid state

The infrared (80–3500 cm^–1) and Raman (10–3500 cm^–1) spectra of solid [(CH₃)₂PS]₂, [(CD₃)₂PS]₂, and [(CH₃CH₂)₂PS]₂ have been recorded. A complete vibrational assignment is proposed for tetramethyldiphosphine disulfide on the basis ofC _2h molecular symmetry. The observed intermolecular vibrations indicate little factor group effects, and no frequency differences were observed for the normal modes of the two different molecules which exist in the crystal as reported from the x-ray study. Most of the observed bands in the spectrum of tetraethyldiphosphine disulfide have been assigned. At least two of the three optical librational modes were observed in the Raman effect.     

The crystal structure of LiBr·(CH3OCH2CH2OCH3)2

The crystal structure of LiBr·(CH₃OCH₂CH₂OCH₃)₂ has been determined from counter data and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupC2/c (C _2h ⁶ , No. 15) witha=13.518(4),b=8.007(3),c=12.252(4) Å,=98.08(2)°, andD _calc=1.35 gcm^–3 forZ=4. The finalR value for 489 observed reflections is 0.033. The lithium and bromine atoms lie on a crystallographic two-fold axis. The structure consists of discrete LiBr·(CH₃OCH₂CH₂OCH₃)₂ units. The Li-Br separation is 2.57(1) Å. The two DME molecules are coordinated to the lithium atom through the four oxygen atoms at an average LiO separation of 2.09(3) Å.     

A Tetranuclear Propane-1,3-Dithiolate Complex, [Fe2(CO)5{Ph2P(CH2)3}{(µ-SCH2)2CH2}]2, with a Bridging 1,6-Bis(diphenylphosphino)hexane Ligand

The 2:1 molar reaction of [Fe₂(CO)₆{(µ-SCH₂)₂CH₂}] (1) and a bidentate diphosphine ligand, 1,6-bis(diphenylphosphino)hexane (dpph), in the presence of Me₃NO resulted in the isolation of [Fe₂(CO)₅{Ph₂P(CH₂)₃}{(µ-SCH₂)₂CH₂}]₂ (2) as red crystals in 71?% yield. The dpph ligand in compound 2, coordinates two Fe₂S₂ subunits as bridging mode and hence makes a linkage between two [Fe₂(CO)₅{(µ-SCH₂)₂CH₂}] fragments. Each Fe₂S₂ butterfly of the complex consists of two fused Fe(S-C-C-C-S) six-membered rings, one of which attains a chair conformation, and the other is necessarily in a boat conformation. Compound 2 has unequivocally been characterized by elemental analysis, IR, ¹H NMR and ³¹P NMR spectroscopy together with single crystal X-ray diffraction studies. Crystals of 2 are triclinic, space group P-1, a = 9.918(4) Å, b = 10.347(3) Å, c = 14.581(5) Å, α?=?72.239(12)º, β?=?80.342(12)º, γ?=?68.550(14)º and Z = 1.

Graphic Abstract

A novel tetranuclear propane-1,3-dithiolate complex, [Fe₂(CO)₅{Ph₂P(CH₂)₃}{(μ-SCH₂)₂CH₂}]₂ (2), bearing a bridging bis(diphenylphosphino)hexane (dpph) ligand, was synthesized from the Me₃NO aided room temperature displacement of carbonyls from [Fe₂(CO)₆{(μ-SCH₂)₂CH₂}] (1), and structurally characterized.

     

Solvent-controlled structures. Synthesis and characterization of complexes Cu(L)2(CH3COO)2 and [Cu2(μ-CH3COO)4(L)2](L)2 [L = N-(4′-methylaniline)-4-pyridinecarboxamide]

Two complexes Cu(L)₂(CH₃COO)₂ (1) and [Cu₂(μ-CH₃COO)₄(L)₂](L)₂ (2) (L = N-(4′-methylaniline)-4-pyridinecarboxamide) have been prepared and their crystal structures have been determined by single-crystal X-ray diffraction. The complexes are obtained by using the same raw materials and reaction conditions except solvents. The presence or absence of water controls the coordination mode to give rise to different structures. The structure of 1 has a triclinic space group P-1 with a = 8.381(3) ?, b = 8.545(4) ?, c = 11.357(5) ?, α = 110.654(6)°, β = 102.388(7)°, γ = 97.889(7)°, V = 722.9(5) ?³, and Z = 1. The structure of 2 has a triclinic space group P-1 with a = 9.121(3) ?, b = 9.454(3) ?, c = 17.233(5) ?, α = 77.374(5)°, β = 89.827(6)°, γ = 74.342(6)°, V = 1393.8(7) ?³, and Z = 1. Supramolecular assemblies have also been found via noncovalent bonds such as hydrogen bonds, π–π stacking interactions.     

X-ray structural analysis of a copper(I) adduct of the Rh(III) trihydride [(triphos)RhH3], with triphos = CH3C(CH2PPh2)3

The binuclear compound [(triphos)RhH(-H)₂Cu(diphos^*)]⁺ with triphos = CH₃C(CH₂PPh₂)₃ and diphos^* = o-C₆H₄(CH₂P(C₆H₁₁)₂)₂ has been prepared and characterized. It crystallizes as [CF₃SO₃] salt in the monoclinic P2₁/c space group with Z = 4, a = 13.802(4)Å, b = 19.462(4)Å, c = 26.604(5)Å, = 99.8(3)°, and V = 7041(3)ų. The structure of the complex consists of two metal fragments with hydride ligands bridging the Rh-Cu contact. The hydride ligands were not located by X-rays but, from the arrangement of the heavy atoms and by methods of potential energy, the most probable positions of two hydride ligands bridging the Rh-Cu interaction and one that remains terminal on the rhodium atom, were obtained.     

Synthesis and crystal structure of N-benzylmethy- lammonium pentachlorothallate (III), [C6H5CH2NH2CH3]2TlCl5

N-Benzylmethylammonium pentachlorothallate (III) salt crystallizes in the monoclinic system P2₁/c with the following unit cell dimensions: a = 10.9540 (8), b = 12.559(1), c = 18.099(2)Å, = 112.1(3)° and Z = 4. The examination of the structure shows an alternate stacking of inorganic layers of pentachlorothallate (III) anions and organic layers of [C₆H₅CH₂NH₂CH₃]⁺ cations parallel to the c axis. The cohesion forces of the packing of N-benzylmethylammonium units in the layer and between two adjacent layers are provided by hydrogen bonds (N—HsCl) and van der Waals contacts.     

Ether cleavage of [2.2.2]cryptand: synthesis and X-ray crystal structure of [NH(CH2CH2I)3][I5]

Treatment of [2.2.2]cryptand1 in toluene with HI(g) has resulted in the formation of a twophase liquid clathrate solution from which the complex [NH(CH₂CH₂I)₃][I₅]2 has been isolated and crystallographically characterized. Crystal data for2: triclinic, space group $P\bar 1$ ,a=9.301(3) Å,b=10.419(3) Å,c=11.078(3) Å, α=90.20(2)^o, β=103.28(2)^o γ=96.50(2)^o,D _c =3.57g/cm³,Z=2,R _f =0.054,R _w =0.054. The salt is a product of an ether cleavage of the macrobicycle. The crystal structure of2 contains [NH(CH₂CH₂I)₃]⁺ ions and zigzag chains of [I₅]^? ions which self-assemble to form alternating layers, of cations and anions.     

Second harmonic generation properties of Ca3(O3C3N3)2 ‐Sr3(O3C3N3)2 solid solutions

Solid solutions of the second harmonic generation (SHG) materials Ca₃(O₃C₃N₃)₂ (CCY) and Sr₃(O₃C₃N₃)₂ (SCY) were prepared via exothermic solid state metathesis reactions from appropriate amounts of the corresponding metal chlorides and potassium cyanate at 525 °C. The change in SHG intensity caused by the successive cation substitution is reported. Differential thermal analyses are used to explore the SCY–K(OCN) phase diagram as a medium for the growth of SCY crystals.     

Structural study of [(CH3)2NH2]2CoCl4 single crystals at room temperature

The structure of the crystals grown from a solution of dimethylammonium and cobalt chlorides is determined. It is found that the crystals have the composition [(CH₃)₂NH₂]₂CoCl₄. At room temperature, the crystals are monoclinic (space group P2₁/c, Z = 4) and the unit cell parameters are as follows: a = 8.545(2) Å, b = 11.447(2) Å, c = 13.313(3) Å, and β = 90.10°. Cations and anions form simple and bifurcated hydrogen bonds N-H?Cl.     

Low frequency vibrations and molecular structure of (CH3)2NPF2

The far infrared spectrum, from 33 to 500 cm^–1, of (CH₃)₂NPF₂ has been recorded in both the gaseous and solid states. The Raman spectrum of both the liquid and solid was also recorded. The three low frequency PF₂ and three NC₂ bending modes as well as the P-N torsion have been assigned. If these bending modes are sensitive to conformational changes, as found in previous studies, then the molecule exists in only one conformation in the gaseous, liquid and solid states for the temperature range –190 to 150 °C. A methyl torsion was assigned at 189 cm^–1 and a barrier to internal rotation of 2·1 kcal/mole was calculated. This low barrier value is discussed in terms of a planar NC₂ moiety.     

Structural and spectroscopic study of a five-coordinate rhodium(I) complex (η-1,5-cyclooctadiene)(η-2, 6-diallylpyridine,N)rhodium (1+) with two different and unusual di-μ-chloro-bis[dichlorodimethylstannate](2−) anions. Crystal structures of [Rh(C8H12)-(C11H13N)]2[{SnCl3(CH3)2}2] · 2CH2C12 and [Rh(C8H12)-(C11H13N)]2[{SnCl3(CH3)2}2]

The preparation and structures of a five-coordinate rhodium(I) complex with 2,6-diallylpyridine (DAP) and cyclooctadiene (COD) ligands with two different [{SnCl₃(CH₃)₂}₂]^2? anions are described, including IR and¹H NMR data. The crystals of the title compounds are both triclinic P¯1: C₄₂H₆₂Cl₆N₂Rh₂Sn₂·2CH₂Cl₂ (1)a=12.200(4),b=13.016(4),c=9.402(2) Å,α=93.92(1),β=100.67(1), γ=115.03(2)°,V _c =1311.2(7) ų,Z= 1,R=0.0312 for 3321 independent observed reflections; C₄₂H₆₂Cl₆N₂Rh₂Sn₂ (2)a=12.187(3),b=12.851(3),c=7.752(2) Å,α=90.15(1),β=101.22(1), γ=73.29(1)°,V _c =1138.8(5) ų,Z=1,R=0.0429 for 4117 independent observed reflections. In both structures the cationic rhodium has a trigonal-bipyramidal environment with theN-pyridine and one double bond of the COD ligand in axial positions and the two allylic double bonds together with the other double COD bond in equatorial positions. Much more interesting are the structures of the anionic parts, which show a different unsymmetrical dimerization through two chlorine bridges. The tin coordination polyhedra, which assume a distorted trigonal-bipyramidal geometry in the monomeric units, achieve an octahedral shape. There is a simple correlation between the Me-Sn-Me angle value and the longest Sn-Cl bond distance.     

Crystal structure and IR spectroscopic study of (CN3H6)2[(UO2)2(C2O4)(CH3COO)4]

Compound (CN₃H₆)₂[(UO₂)₂(C₂O₄)(CH₃COO)₄] is synthesized and characterized by IR spectroscopy and single-crystal X-ray diffraction [a = 8.5264(2) Å, b = 13.8438(4) Å, c = 10.7284(2) Å, β = 103.543(1)°, space group P2₁/n, Z = 2, and R = 0.0258]. The main structural units of the crystals are binuclear [(UO₂)₂C₂O₄(CH₃COO)₄]^2? groups, which belong to the A ₂ K ⁰² B ₄ ⁰¹ crystal chemical group of uranyl complexes (A = UO ₂ ²⁺ , K ⁰² = C₂O ₄ ^2? , and B ⁰¹ = CH₃COO^?). The coordination polyhedron of the uranium atom is the UO₈ hexagonal bipyramid with the oxygen atoms of the uranyl ion at the axial positions. Uranium-containing groups and guanidinium cations are connected by electrostatic interactions and by the hydrogen bond system, which involves hydrogen atoms of guanidinium cations and oxygen atoms of oxalate and acetate anions. The results of the spectroscopic study of the compound agree with the X-ray diffraction data.