Synthesis and crystal structure of divaleratobis(nicotinamide)copper(II)

A copper(II) valerate complex with nicotinamide (L) [CuL₂(C₄H₉COO)₂] (I) has been synthesized and studied by IR spectroscopy and thermogravimetry. The crystal structure has been determined. The crystals of 1 are monoclinic, a = 11.297(1) Å, b = 6.666(1) Å, c = 16.873(2) Å, b = 108.50(1)°, V = 1204.9(3) ų, Z = 2, space group P2₁/c. The structural units of the crystal of I are centrosymmetric tetragonal bipyramidal (4+2) complex molecules. The equatorial positions of the bipyramid are occupied by trans-arranged pairs of O (Cu-O, 1.973 Å) and N (Cu-N, 2.006 Å) atoms, and the axial positions are occupied by the second O atoms of the valerate anions located at longer distances (Cu-O, 2.506 Å). The supramolecular associates formed in the crystal are layers of hydrogen-bonded complexes. The disordered hydrocarbon “tails” of the valerate groups point toward the interlayer space.     

THE CRYSTAL AND MOLECULAR STRUCTURE OF RUBIDIUM BIS(PYRIDINE-2,6-DICARBOXYLATO)-CHROMATE(III)

Abstract

A three dimensional X-ray structural analysis of rubidium bis (pyridine-2,6-dicarboxylato)chromate(III), Rb[Cr(dipic)₂], has been carried out. The structure was refined by full matrix least-squares methods, using 713 observed independent reflections recorded at room temperature, to a conventional weighted R of 0.034. The crystals are tetragonal with a=b=6.950(3) Å, c=29.47(1) Å, space group 14 1/a and Z=4. The point group symmetry of the [Cr(dipic)₂]^? ion is S₄. The Cr–N and Cr–O distances (1.974(4) and 2.000(3) Å respectively) noticeably differ from the usual values in aminoacid chromium(III) complexes. The π bonding effect of the pyridine nitrogen atom corroborates the previous spectral studies on the sodium salt of this complex. The lability of [Cr(dipic)₂]^? in acid solution has been tentatively explained on the basis of the relatively severe strain within the complex ion.     

Coordination Chemistry of Sulfonyl Amides. 2 The Crystal Structure of Copper(II) and Silver(I) Complexes of N,N-4-Toluenesulfonyl-2-Pyridylaminato Ligand

Three structures containing the N,N-4-toluenesulfonyl-2-pyridylaminato ligand are presented. The brown crystal of Cu₂L₄ (L =N,N-4-toluenesulfonyl-2-pyridylaminato) was found to crystallize in the monoclinic space group P2,/c with a = 15.762(12), b = 15.552(5), c = 20.505(11) Å, β = 104.14(7)°; V = 4874(5) Å^3;Z = 4; the final R_F = 0.050, R_WF = 0.049 for 5142 observed reflections and 612 variables. The Cu-Cu distance is small, 2.516(2) Å and the complex is diamagnetic at room temperature. The colorless crystal of Ag₂L was found to crystallize in the monoclinic space group P2_t/n with a = 9.620(2), b = 5.625(2), c ? 23.250(3) Å, Å = 94.72(1)°; V = 1254.0(5) ų; Z = 2; the final R_F = 0.027; R_WF = 0.028 for 1929 observed reflections and 164 variables. The Ag-Ag distance is 2.739(1) Å The green crystal of CuL₂ (py)₂was found to crystallize in the monoclinic space group P2₁ with a = 9.366(2), b = 20.615(7), c = 9.862(2) Å,β = 116.73(2)°; V = 1700.5(8) ų; Z = 2; the final R_F = 0.037; R_WF = 0.038 for 1636 observed reflections and 423 variables. A reversible transformation between Cu₂L₄ and CuL₂(py)₂ is reported.     

Contributions on thermal behaviour and crystal chemistry of anhydrous phosphates. XIX. Tri-chromium(II)-bis-phosphate Cr3(PO4)2 (≙ Cr6(PO4)4) – A transition metal(II)-orthophosphate with new structure type

Deep blue-violet single crystals of hitherto unknown chromous orthophosphate have been obtained reducing CrPO₄ by elemental Cr at temperatures above 1050°C in evacuated silica ampoules (NH₄I or I₂ as mineraliser). The complex structure of Cr₃(PO₄)₂ (P2₁2₁2₁, Z = 8, a = 8.4849(10) Å, b = 10.3317(10) Å, c = 14.206(2) Å) contains six crystallographically independent Cr²⁺ per unit cell. Five of them are coordinated by four oxygen atoms which form a distorted (roof shaped) square plane as first coordination sphere at interatomic distances 1.96 Å ? d(Cr? O) ? 2.15 Å. Their coordination is completed by additional oxygen atoms (2 or 3) at distances 2.32 Å ? d(Cr? O) ? 3.21 Å. The sixth Cr²⁺ shows six-fold octahedral coordination with strong radial distortion (d(Cr? O): 1.97, 2.04, 2.15, 2.28, 2.29, 2.53 Å). The four different [PO₄] groups exhibit only minor deviations from ideal tetrahedral geometry (1.51 Å ? d(P? O) ? 1.57 Å, 104.3° ? ∠(O? P? O) ? 114.4°). An unusually low magnetic moment μ_exp = 4.28(2) μ_B (θ_P = ?54.8(5) K) has been observed for Cr²⁺.     

Crystal structure of monoaquatetra(3,5-dimethylpyrazole)copper(II) nitrate [Cu(C5H8N2)4(H2O)](NO3)2

The crystal structure of monoaquatetra(3,5-dimethylpyrazole)copper(II) nitrate [Cu(C₅H₈N₂)₄(H₂O)]×(NO₃)₂ is determined (Syntex P2₁ automated diffractometer, θ/2θ scan mode within the 2θ range 3–55° at a variable rate, V_min=5 deg/min, λMoK_α graphite monochromator, 5170/2349 measured/observed I_hk1, absorption taken into account experimentally, R_aniso=0.069). The parameters of the monoclinic unit cell are as follows: a=23.569(4), b=8.177(2), c=17.250(6) Å, β=121.65(2)°, V=2830(2) ų, Z=4C₂₀H₃₄CuN₁₀O₇, d_calc=1.388 g/cm³. The space group P2₁ was chosen by the process of structure solution and refinement. The structure is of island type. The complex cations [CuL₄(H₂O)]²⁺ and the (NO₃)^? anions form mixed layers in the planes parallel to (010) at y?0.36 and 0.87. The central atoms of two crystallographically independent complex cations [CuL₄(H₂O)]²⁺ are surrounded with five atoms (O_{H 2 O}+4N) with average Cu?O_{H 2 O} and Cu?N distances of 2.23(2) and 2.04(4), respectively, which form distorted trigonal bipyramids. The average bond lengths in the pyrazole rings are the following: N?N=1.40, N?C=1.40, (C?C)_ring=1.42, and C_ring?C_Me=1.50 Å.     

Ru(II) COMPLEXES CONTAINING CHELATING PHOSPHINE LIGANDS. SYNTHESIS,CHARACTERIZATION, AND X-RAY CRYSTAL STRUCTURES OF DICHLOROBIS(1,2-BIS(DIPHENYLPHOSPHINO)ETHANE)Ru(II) AND THE COORDINATIVELY UNSATURATED TRIGONAL-BIPYRAMIDAL CATION,CHLOROBIS-(1,2-BIS(DIPHENYLPHOSPHINO)ETHANE)Ru(II)

Abstract

The reaction of trans-RuCl₂(dppe)₂ (1), with AgBF₄ in tetrahydrofuran leads to abstraction of one of the halide ligands to produce the trigonal-bipyrimidal complex, [RuCl(dppe)₂]BF₄ (2). Both products are characterized by ³¹P NMR spectroscopy and their crystal structures determined. For the coordinatively unsaturated trigonal-bipyramidal complex (2), we found no evidence for the presence of more than one species or fluxional behaviour at room temperature in the ³¹P NMR spectrum. This complex was found to possess a trigonal-bipyramidal geometry in the solid state. Crystals of 1 are monoclinic, space group P2₁/c with a = 23.713(4)Å, b=11.156(1)Å, c = 17.595(2)Å, β=103.23(1) and v=4531(1)ų. Convergence to conventional R values of R=0.043 and R_w = 0.042 was obtained for 416 variable parameters and 2746 reflections with I>3σ(I). Compound 2 in triclinic, P1, a=12.482(3)Å, b=12.543(3)Å, c=17.582(3)Å, α = 87.52(2)°, β= 72.70(2)° γ = 74.35(2)° and V= 2529(1)ų. Values of R = 0.072 and R_w = 0.097 were obtained for 487 variable parameters and 3242 reflections with I>3σ(I)     

Darstellung und Kristallstruktur von Tris(äthylendiamin)kobalt(III)-trichlorostannat(II)-dichlorid, [Co(en)3][SnCl3]Cl2

Preparation and Crystal Structure of Tris(ethylenediamine) cobalt(III)-trichlorostannate(II)-dichloride, [Co(en)₃] [SnCl₃]Cl₂ The title compound has been prepared from [Co(en)₃]Cl₃ and SnCl₂ · 2H₂O in aqueous HCl solution. It crystallizes in the orthorhombic space group Pbca, with a = 21.906(7), b = 10.607(3), c = 15.356(7) Å. The crystal structure has been determined from 1606 independent reflections by Patterson snd Fourier syntheses, and has been refined by least squares methods to R = 0.074. The [Co(en)₃]³⁺ ion is found to have the conformation of Λ(δδλ) resp. Δ(λλδ). The structure of the [SnCl₃]^? ion corresponds to a distorted tetrahedron, in which one site is occupied by the stereochemically active 5s electron pair. The following Sn? Cl distances have been found 2.493(7), 2.492(5), 2.479(7) Å, the distances of the two anionic Cl atoms from Sn are >4 Å.     

Crystal structure and thermal investigation of bis-(1-thenoyl-4,4,4-trifluorobutan-1,3-dionato) lead(II)

Lead(II) complex with thenoyltrifluoroacetone has been prepared and characterized by IR spectroscopy, powder and single crystal X-ray diffraction. Crystal data for PbO₄S₂F₆C₁₆H₈: a = 20.457(4) Å, b = 11.292(2) Å, c = 8.409(2) Å; β = 91.37(3)°, space group C2/c, Z = 4, d _calc = 2.222 g/cm³. The molecule of the complex is non-planar, average distances Pb-O are 2.384 Å, chelate angle O-Pb-O is 75.0°. The structure is of polymeric chain nature, Pb...Pb separation in the chains being 4.311 Å. The complex Pb(ttf)₂ is stable under heating up to 250°C. The compound is less volatile than Cu(ttf)₂ or Fe(ttf)₃.     

Synthesis,Characterization and Crystal Structure of a Nickel(II) Schiff Base Complex Derived from Acetylacetone and Ethylenediamine

The square-planar nickel (II) complex of composition [Ni(bae)]·½H₂O (1) [where H₂bae is bis(acetylacetone)ethylenediamine] has been synthesized by [2 + 1] template condensation of acetylacetone and ethylenediamine in the presence of NiCl₂·6H₂O and characterized. An X-ray structure determination of the complex has been completed. Average Ni-N and Ni-O distances are, respectively, 1.86(2) Å and 1.849(14) Å. N···N bite distance and bite angle are 2.627(6) Å and 87.2(2)°, respectively, for the five-membered chelate ring. The water molecule forms hydrogen bonds with O atoms of two complex molecules.     

Structures of Iodophenyltellurium(II) and Diiododi-(β-naphtyl)tellurium(IV)

The reactions between diphenyl ditelluride, (PhTe)₂, or di(β-naphtyl)ditelluride, (β-naphtylTe)₂, with equivalent amounts of iodine have been reinvestigated and the crystal and molecular structures of iodophenyltellurium(II), (PhTeI)₄, and diiododi-(β-naphtyl)tellurium(IV), (β-naphtyl)₂TeI₂, have been determined. The structure of iodophenyltellurium(II) (space group Cc, a = 13.850(5) Å, b = 13.852(3) Å, c = 16.494(6) Å and β = 101.69(2)°, Z = 4) is built up by four PhTeI units which are linked by weak Te–Te interactions with Te–Te distances between 3.152(5) Å and 3.182(4) Å. The angles between the tellurium atoms are approximately 90° giving an almost perfect square. Long range secondary bonds (Te–I: about 4.2 Å) link the tetrameric units to give an infinite two-dimensional network. Iodo(β-naphtyl)tellurium(II) is less stable than the phenyl derivative. Solutions of this compound decompose under formation of elemental tellurium and (β-naphtyl)₂TeI₂. (β-Naphtyl)₂TeI₂ crystallises in the monoclinic space group C 2/c (a = 21.198(6) Å, b = 5.8921(8) Å, c = 16.651(5) Å, β = 114.77(2)°). The tellurium atom is situated on a two-fold crystallographic axis and Te–I and Te–C bond lengths of 2.899(1) and 2.108(7) Å have been determined.     

Crystal structure of <Emphasis Type="Italic">tris</Emphasis>-(dipivaloylmethanato) (ethylendiamine)yttrium(III)

The structure of a mixed-ligand complex tris-(dipivaloylmethanato)(ethylendiamine)yttrium(III) [Y(en)(dpm)₃] is studied at 150(2) K by single crystal XRD. The crystallographic data for C₃₅H₆₅N₂O₆Y are as follows: space group P2₁/c, a = 10.3771(3) Å, b = 26.3566(8) Å, c = 14.8412(4) Å, β = 100.385(2)°, V = 3992.6(2) ų, Z = 4. The structure is molecular. The coordination environment of yttrium atoms is square antiprismatic; the Y–О distances are 2.2597(13)-2.3760(12) Å and Y–N distances are 2.5381(16) Å and 2.5499(17) Å.     

Die Kristallstruktur von Lithiummesitolat [{LiOC6H2-2,4,6-(CH3)3}4(THF)3]

X-Ray Structure of [{LiOC₆H₂-2,4,6-(CH₃)₃}₄(THF)₃] The title compound crystallized from a THF/OEt₂ solution. Its crystal structure (monoclinic, P2₁/c, a = 21.362(3), b = 13.441(2), c = 17.188(2) Å, β = 98.39(1)°, Z = 4, R = 0,0911, wR² = 0,2562) is built up by cuban-like tetrameric units. Three of the four Li cations attain a coordination number of four by binding to an additional THF molecule. Li(4) without THF coordination has a short distance to one ortho-methyl group (Li(4)…C(27) 2.669(10) Å). The Li–O_ph bonding distances vary from 1.869(10) to 2.051(10) Å (average 1.97 Å); the average bonding distance for Li–O_THF is 2.012(10) Å. Averaged bonding angles for Li–O_ph–Li′ and O_ph–Li–O′_ph amount to 84.4(4)° and 95.4(4)°, respectively. The Li…Li distances significantly differ from each other. They range from 2.556(12) to 2.739(11) Å (average 2.65(1) Å).     

Schwermetall-π-Komplexe. X. Synthese und Kristallstruktur von {[(1,3,5-(CH3)3C6H3)2Tl][AlCl4]}2: ein arenstabilisiertes dimeres Thallium(I)-tetrachloroaluminat

π-Complexes of Heavy Metals. X. Synthesis and Crystal Structure of {[(1,3,5-(CH₃)₃C₆H₃)₂Tl][AlCl₄]}₂: an Arene Stabilized Dimeric Thallium(I) Tetrachloroaluminate From a solution of AlCl₃ and TlCl in mesitylene, the bis(arene)thallium complex {[(1,3,5-(CH₃)₃C₆H₃)₂Tl][AlCl₄]}₂ ( 1 ) (space group P2₁/c with a = 19.575(4) Å, b = 12.436(2) Å, c = 19.415(4) Å, β = 101.69(3)° at T = ?90 ± 1°C; Z = 4) will crystallize at low temperature. This compound can be described as a dimeric thallium(I) tetrachloroaluminate with a sceleton similar to that of (TeI₄)₄, shielded by four arenes, in pairs coordinated at the thallium atoms. In the solid state the complete configuration has point group symmetry 1 (C₁). Tl? Cl distances ranging from 3.292(3) to 3.679(3) Å point out an ionic bonding situation between arene₂Tl⁺ and AlCl₄^? fragments. The strengths of the η⁶ like Tl-arene interactions are characterized by distances Tl(1)–C of 3.250 Å and 3.315 Å, and Tl(2)? C of 3.285 Å and 3.328 Å and a temperature of release of all arene molecules of 61°C, which has been determined by differential thermal analysis, to yield pure thallium(I) tetrachloroaluminate.     

Crystal and molecular structure of monomeric yttrium(III) dipivalylmethanate. Arrangement of adsorbed layers

Crystal structure of monomeric yttrium(III) dipivalylmethanate, YO₆C₃₃H₅₇, has been studied by X-ray diffraction. Crystal data: a=17.868(3), b=9.977(2), c=10.633(2) Å, V=1895.7 ų, space group Pmn2₁, Z=2, d_calc=1.116, d_exp=1.119 g/cm³. The compound has a molecular structure and consists of monomeric molecules with a proper symmetry plane m. In the metallocycle lying in this plane, Y-O interatomic distances and O?Y?O bond angles markedly differ from the similar distances and angles in the other two planes. The average Y?O, O?C, and C?C distances are 2.22, 1.25, and 1.46 Å, respectively. As a result of comparative crystal-chemical analysis carried out for related compounds, the coordination polyhedra around the yttrium atoms were found to be trigonal prisms formed by six oxygen atoms of three bidentate ligands. Layers ～1 μm thick were obtained by vapor condensation of the complex on different supports; the layers were investigated by XRD. Irrespective of the type of support, the layers are oriented polycrystalline films with [001] texture axes. Arrangement of the adsorbed molecules of the complex is analyzed. The layers are self-organized into close-packed structures with C(CH₃)₃ groups oriented toward supports.     

STRUCTURE AND PROPERTIES OF N,N-DI-n-BUTYLDITHIOCARBAMATO-1, 2-DICYANOETHENE-1, 2-DITHIOLATO-GOLD(III)

Abstract

The crystal and molecular structure and some spectral data of the compound N,N-di-n-butyldithiocarbamato-1, 2-dicyanoethene-1, 2-dithiolato-gold(III), AuS₂CN(C₄H₉)₂S₂C₂(CN)₂, are reported. The crystal structure has been determined from a three-dimensional single-crystal X-ray diffraction study. The orthorombic cell, space group Pbca, with a=14.066(3), b=28.980(2) and c=9.192(2) Å, contains eight formula units. Intensity data were collected on an automatic diffractometer. The structural parameters were refined by full-matrix least-squares methods to a conventional R-factor of 0.047 for 1587 independent non-zero reflections. The structure determination proved the compound to be a mixed dithiocarbamato-dithiolato complex, Au(dtc)(mnt), (dtc=N,N-di-n-butyl-dithiocarbamate, mnt=maleonitriledithiolate ≡ 1, 2-dicyanoethene-1, 2-dithiolate), as expected from spectral data. The gold atom is in approximately square-planar coordination, however, deviations from mm2 (C_2#) symmetry are considerable. Au-S bond distances in the dtc-moiety (2.329(5) Å and 2.324(5) Å) are significantly longer than those in the mnt-moiety (2.303(5) Å and 2.284(5) Å). The molecules are packed pairwise around inversion centres with relatively short intermolecular S-S distances.     

Bis(triphenylphosphin)iminium-bis(methoxo)phthalocyaninato(2–)ferrat(III) – Synthese und Kristallstruktur

Bis(triphenylphosphine)iminium Bis(methoxo)phthalocyaninato(2–)ferrate(III) – Synthesis and Crystal Structure Chlorophthalocyaninato(2–)ferrate(III) reacts with bis(triphenylphosphine)iminium hydroxide in methanol/acetone solution to yield blue crystals of bis(triphenylphosphine)iminium bis(methoxo)phthalocyaninato(2–)ferrate(III). The complex salt crystallizes as an acetone/methanol solvate (^bPNP)[Fe(OCH₃)₂pc^2–] · (CH₃)₂CO · 1.5 CH₃OH in the triclinic space group P 1 (no. 2) with the cell parameters a = 13.160(5) Å, b = 15.480(5) Å, c = 17.140(5) Å, α = 97.54(5)°, β = 91.79(5)°, γ = 95.44(5)°. The Fe atom is located in the centre of the pc^2– ligand coordinating four isoindole N atoms (N_iso) of the pc^2– ligand and two O atoms of the methoxo ligands in a mutual trans arrangement. The average Fe–O and Fe–N_iso distances are 1.887 and 1.943 Å, respectively. The cation adopts the bent conformation (< P–N–P = 140.4(2)°) with P–N distances of 1.579(3) and 1.575(3) Å.     

SYNTHESIS AND CHARACTERIZATION OF MANGANESE(III) HYDROXYL-CONTAINING SCHIFF-BASE COMPLEXES: [Mn(III)(Hvanpa)2(NCS)] AND [Mn(III)(Hvanpa)2]Cl · H2O (H2vanpa ˭ 1-(3-METHOXYSALICYLALDENEAMINO)-3-HYDROXYPROPANE)

Abstract

The manganese complexes, [Mn(III)(Hvanpa)₂(NCS)] (1) and [Mn(III)(Hvanpa)₂]Cl · H₂O (2), have been prepared and the crystal structure of complex 2 determined using X-ray crystallography. The monomeric complex has a six-coordinate octahedral geometry. The complex crystallizes in the triclinic space group P-1 with a = 11.446(5) Å, b = 12.782(6) Å, c = 9.023(3) Å, α = 93.92(3)°, β = 97.05(3)°, γ = 65.42(2)°, V = 1169.0(9) ų and Z = 2. The Mn-O and Mn-N distances in the equatorial plane are in agreement with those found for other manganese (III) Schiff-base complexes. In the axial direction, the Mn-O distances of 2.256(3) and 2.236(3) Å, respectively, are about 0.4 Å longer than those in the equatorial plane due to Jahn-Teller distortion at the d ⁴ manganese(III) center. In the crystal, each chloride ion is linked through hydrogen bonding with two hydrogen atoms from the coordinated hydroxyl groups at the apical site. The lattice water molecules also interact with the phenolic oxygen atoms through hydrogen bonding.     

Synthesis and Crystal Structures of Nickel(II) and Copper(II) Complexes of Meso-3,6,6,9-Tetramethyl-4,8-Diazaundecane-2,10-Dione Dioxime

The nickel(II) and copper(II) complexes of meso-3,6,6,9-tetramethyl-4,8-diazaundecane-2,10-dione dioxime (meso-HM-PAO) have an intramolecular hydrogen bond between cis oxime groups. [Cu(meso-HM-PAO-H)(H₂O)](NCS) crystallizes in space group P2₁/n with a = 7.692(1), b = 12.028(2), c=20.235(3) Å, β=93.03(1)°, Z = 4 and Dc=1.46 g/cm³. The final R value for this complex was 0.034 for 2223 observed reflections with I ≥ 2.5σ (I). The Cu(II) coordination is a distorted square pyramid. The Cu(II) ion is five-coorinated with the diazadioxime N atoms equatorial and water O atom axial. The Cu(II) is 0.12 Å from the equatorial plane towards the hydrate. The equatorial Cu-N distances span a narrow range, 1.953(3)-1.999(3) Å. The axial Cu-O distance is 2.314(3) Å. The thiocyanate group is almost linear. The intramolecular O ?O hydrogen bond length is 2.479(4) Å. [Ni(meso-HM-PAO-H)](ClO₄) crystallizes in space group P2₁/c with a = 14.774(3), b = 12.752(3), c = 20.035(4) Å, β = 92.94(3)°, Z = 8 and Dc = 1.51 g/cm³. The final R value for the complex was 0.053 for 4794 observed reflections with F ≥ 4σ (F). The coordination about Ni(II) is a slightly distorted square plane. The Ni(II) ion is 0.0673(7) Å from the best plane of the four donor nitrogen atoms away from the perchlorate ion. The Ni-N distances span a narrow range 1.863(4)-1.927(4) Å. There are two molecules per asymmetrical unit resulting in eight molecules being packed in an unit cell; they are bound together by van der Waals interactions. The O-H ?O bonds of these complexes give characteristic infrared absorptions as well as chemical shift of the ¹H NMR signal (Ni complex).     

CRYSTAL AND MOLECULAR STRUCTURE OF BIS(TRIPHENYLBENZYLPHOSPHONIUM) TETRABROMOCADMATE

Abstract

The molecular and crystal structure of bis(triphenylbenzylphosphonium)tetrabromocadmate has been determined by x-ray diffractometer data. Crystals are triclinic, space-group Pl with two formula units in a unit-cell of dimensions a = 12.506(6), b = 10.471(5), c = 18.396(13) Å, α = 93.07(4)°, β = 105.75(5)°, γ = 92.58(4)°. The structure was solved by direct and Fourier methods and refined by least-squares techniques to R = 0.061 for 3723 independent observed reflections. The structure consists of tetrabromocadmate (II) anions and triphenylbenzylphosphonium cations, both with a quasi-perfect tetrahedral symmetry around the cadmium and phosphorus atoms. The most significant average bond distances are: Cd-Br, 2.588(2) Å, P[sbnd]C (Phen), 1.794(5) Å and P[sbnd]CH₂, 1.806(6) Å. The P[sbnd]C (Phen) bonds are in slightly distorted staggered conformation (gauche-, gauche +, and trans) in respect of the C (Phen)-CH₂ bonds of the benzyl residues. The interatomic distances between the ions correspond to the usual Van der Waals distances.     

Structure Cristalline de l'Arseniate Double de Potassium et de Zirconium: KZr2(AsO4)3

Crystal Structure of KZr₂(AsO₄)₃ KZr₂(AsO₄)₃ crystals have been prepared by the flux method. The compound crystallizes in the rhombohedral system with the parameters: a = 9.028(1), c = 24.399(3) Å. The density is d = 3.694 g/cm³ and Z = 6. The space group is R3 c. The structure has been solved by isotypism with that of NaZr₂(PO₄)₃ to R = 0.041, for 353 independent reflections. It consists in 3-dimensional chains of AsO₄ tetrahedra and ZrO₆ octahedra. K⁺ ions are the center of the antiprism with K—O distances equal to 2.813 Å. The Zr–O and As–O distances have the same values of those usually observed (Zr–O = 2,05 Å and As–O = 1.66 Å).