Search results for "Crystal system"
showing 10 items of 13557 documents
Rhenium(IV) cyanate complexes: Synthesis, crystal structures and magnetic properties of NBu4[ReBr4(OCN)(DMF)] and (NBu4)2[ReBr(OCN)2(NCO)3]
2006
Abstract Two new rhenium(IV) mononuclear compounds of formula NBu4[ReBr4(OCN)(DMF)] (1) and (NBu4)2[ReBr(OCN)2(NCO)3] (2) (NBu4 = tetrabutylammonium cation, OCN = O-bonded cyanate anion, NCO = N-bonded cyanate anion and DMF = N,N-dimethylformamide) have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. 1 crystallizes in the monoclinic system with the space group P21/n, whereas 2 crystallizes in the triclinic one with P 1 ¯ as space group. In both complexes the rhenium atom is six-coordinated, in 1 by four Br atoms in the equatorial plane, and two trans-oxygen atoms, one of a DMF molecule and another one from a cyanato group, while in 2 by one brom…
A New Heptanuclear Cobalt(II) Cluster Encapsulated in a Novel Heteropolyoxometalate Topology: Synthesis, Structure, and Magnetic Properties of [Co7(…
2004
The synthesis and the structural and magnetic characterization of a novel heptanuclear cobalt cluster encapsulated in a heteropolyoxotungstate is reported. This complex shows how it is possible to control the nuclearity of the Co clusters formed in a tungstate solution by slightly changing the synthetic conditions, and the relevance of pH in this regard. This heptanuclear complex [Co7(H2O)2(OH)2P2W25O94]16- (Co7) crystallizes in the triclinic space group P1 (a = 12.3403(6) A, b = 22.5966(11) A, c = 23.2645(12) A, α = 68.7830(11)°, β = 83.7981(12)°, γ = 78.5423(13)°, V = 5922.4(5) A3, Z = 2) and is formed by six CoO6 octahedra from two Co3 trimers sustained by Keggin trivacant fragments held…
Relations between compression and thermal contraction in 1,2,4-trichlorobenzene and melting of trichlorobenzene isomers
2015
The compression and thermal expansion of crystalline 1,2,4-trichlorobenzene, C6H3Cl3, 124TCB, investigated under isobaric and isothermal conditions, are in reverse relation, as for most of crystals, however, the isochoric strain along direction c is clearly different from those along a and b. Single crystals of 124TCB have been in situ grown under isochoric and isobaric conditions, at 270 K/0.1 MPa and 295 K/0.16 GPa, and also at 100 K/0.1 MPa and 295 K/0.64 GPa, when the unit-cell volume is similar. All crystallizations yielded the same phase, of monoclinic space group P21/n, with two symmetry-independent molecules (Z′ = 2). The structure is governed by Cl⋯Cl and Cl⋯H interactions and the …
Syntheses and crystal structures of three novel Cu(II) coordination polymers of different dimensionality constructed from Cu(II) carboxylates (carbox…
2004
Abstract We herein report three new coordination polymers generated from Cu(II) carboxylates (mal, 2ac, fum) and conformationally flexible bifunctional IX as building blocks. All the three complexes adopt unique structures in the solid state. The complex [Cu2(mal)2(IX)2(H2O)6]n crystallizes as orthorhombic co-linear rods with space group P2(1) P2(1) P2(1). Each rod is further formed of two tightly intertwined strings. The second polymer [Cu2(ac)4(IX)2]n crystallizes with space group P1 which consists of two sets of intersecting 2D sheets composed of parallel rods which interpenetrate to form a fully interlocked 3D structure. In both these complexes IX coordinates in the anti mode. The third…
Atomic structure solution of the complex quasicrystal approximant Al77Rh15Ru8 from electron diffraction data
2014
The crystal structure of the novel Al77Rh15Ru8phase (which is an approximant of decagonal quasicrystals) was determined using modern direct methods (MDM) applied to automated electron diffraction tomography (ADT) data. The Al77Rh15Ru8E-phase is orthorhombic [Pbma,a= 23.40 (5),b= 16.20 (4) andc= 20.00 (5) Å] and has one of the most complicated intermetallic structures solved solely by electron diffraction methods. Its structural model consists of 78 unique atomic positions in the unit cell (19 Rh/Ru and 59 Al). Precession electron diffraction (PED) patterns and high-resolution electron microscopy (HRTEM) images were used for the validation of the proposed atomic model. The structure of the E…
Crystal and molecular structure of anhydrous betaine, (CH3)3NCH2CO2
1999
Abstract 1–Carboxy–N,N,N–trimethylmethanamanium inner salt or anhydrous betaine, (CH3)3NCH2CO2, FW=117.15 gmol −1 , crystallizes in the orthorhombic space group Pnma with a=14.544(2) A , b=6.859(3) A , c=6.131(1) A , V=611.7(3) A 3 , Z=4, D x =1.27 Mgm −3 , λ (MoK α )=0.71073 A , μ =0.091 mm −1 . The structure was resolved by direct methods and refined by least-square calculations to R=0.038 for 531 reflections. Observed changes in bond angles imply that there is a repulsion between nitrogen and oxygen. The melting point (measured at onset) is 570 K. FTIR spectra of anhydrous betaine and monohydrate were recorded. Clear differences were found between the two compounds based on infrared (i.r…
Crystal structures and thermal behavior of bis[dibenzyldimethylammonium]CuBr4, bis[dibenzyldimethylammonium]CuCl4 and bis[dimethyldi(2-phenylethyl)am…
2006
Abstract Bis[dibenzyldimethylammonium]CuBr4, bis[dibenzyldimethylammonium]CuCl4 and bis[dimethyldi(2-phenylethyl)ammonium]CuBr4 were crystallized from acetonitrile and/or dilute HX solutions. Five different kinds of single crystals were obtained. In the case of bis[dibenzyldimethylammonium]CuX4 (X=Br or Cl), the acetonitrile molecules cocrystallized into the crystal structure when acetonitrile solution was used. As a result, the isomorphic structures of Bis[dibenzyldimethylammonium]CuX4·0.5 CH3CN (X=Br or Cl) in monoclinic space group P21/n were obtained. When a dilute HX solution was used, the bis[dibenzyldimethylammonium]CuX4 (X=Br or Cl) crystallized without solvent molecules. The formed…
An Inorganic Double Helix Sheathing Alkali Metal Cations: ANb2P2S12(A=K, Rb, Cs), A Series of Thiophosphates Close to the Metal-Nonmetal Boundary-Cha…
2004
The new quaternary niobium thiophosphates ANb 2 P 2 S 1 2 (A=K, Rb, Cs) have been prepared and characterized. The title compounds were synthesized by reacting Nb metal, A 2 S, P 2 S 5 , and S at 600-700°C in evacuated silica tubes. They crystallize as "stuffed" variants of the tetragonal TaPS 6 structure type in the tetragonal space group I42d with eight formula units per unit cell and lattice constants a=15.923(2) and c=13.238(3) A for CsNb 2 P 2 S 1 2 , a= 15.887(3) and c=13.132(3) A for RbNb 2 P 2 S 1 2 , and a=15.850(2) and c= 13.119(3) A for KNb 2 P 2 S 1 2 . Their structures are based on double helices formed from interpenetrating, noninteracting spiral chains of binuclear [Nb 2 S 1 2…
Synthesis and Characterisation of a New Series of Bistable Iron(II) Spin-Crossover 2D Metal-Organic Frameworks
2009
Twelve coordination polymers with formula {Fe(3-Xpy)(2)[M(II)(CN)(4)]} (M(II): Ni, Pd, Pt; X: F, Cl, Br, I; py: pyridine) have been synthesised, and their crystal structures have been determined by single-crystal or powder X-ray analysis. All of the fluoro and iodo compounds, as well as the chloro derivative in which M(II) is Pt, crystallise in the monoclinic C2/m space group, whereas the rest of the chloro and all of the bromo derivatives crystallise in the orthorhombic Pnc2 space group. In all cases, the iron(II) atom resides in a pseudo-octahedral [FeN(6)] coordination core, with similar bond lengths and angles in the various derivatives. The major difference between the two kinds of str…
Synthesis, characterization and thermal properties of nine quaternary dialkyldiaralkylammonium chlorides
2006
Abstract Nine R 2 R 2 ′ N + Cl − (R=benzyl, 2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, 2-phenylethyl or 3-phenylpropyl; R′=ethyl or methyl) quaternary dialkyldiaralkylammonium chlorides were synthesized by treating dimethylformamide or diethylformamide with non-substituted or substituted arylalkyl (aralkyl) halide in the presence of sodium carbonate. The 1H NMR, 13C NMR spectroscopy, mass spectroscopy and elemental analysis were used to characterize the synthesized products. The crystal structures of six compounds were determined by X-ray single crystal diffraction. Four of the compounds crystallized in monoclinic space groups C2/c and P21/c (or P21/n), one in triclinic space group P−1…