Anisotropic Thermal Parameters Research Articles

Structure of cyclohexylsilanetriol: The first x-ray crystal structure of a silanetriol

The structure of cyclohexylsilanetriol C6H11Si(OH)3 has been determined by single-crystal x-ray diffraction methods. The molecule crystallizes in the monoclinic system, space group C2/m, with a=7.876(3), b=6.637(6), c=15.802(11) Å, β=95.51(3)° at −60 °C, and Z=4. The intensities of 1031 independent reflections were measured using the ω-scan technique on a Syntex P3 diffractometer (monochromatic MoKα). The final R factor is 0.057, based on anisotropic thermal parameters for all atoms except hydrogens. The molecules pack in a head-to-head, tail-to-tail arrangement with the cyclohexyl groups forming a hydrophobic double sheet and the silanetriol groups forming a second, hydrophilic, double sheet. The structure has a distorted hydrogen bond network with the hydrogen on each oxygen having equal probability of hydrogen bonding to oxygens in two different molecules. Two types of hydrogen bonds exist in the hydrophilic double sheet; O(1)⋅⋅⋅O(2) intrasheet hydrogen bonds, 2.724(2)Å, and O(2)⋅⋅⋅O(2) intrasheet hydrogen bond, 2.722(3) Å.

The structure of the hollandite type phase of synroc b in the temperature range 20–1060°c

The crystal structure of the hollandite type phase Ba 1.17Ti 5.04Al 2.10O 16 has been determined by neutron diffraction powder methods in the temperature range 20–1060°C. The lattice parameters, the positional parameters and the anisotropic thermal parameters of each atom have been determined at seven temperatures. The principal results are: 1. (1) the thermal expansion coefficients are almost isotropic, α a = (10.40 ± 0.25) × 10 −6 , α c = (11.17 ± 0.35) × 10 −6 ; 2. (2) the fractional atomic coordinates do not change in this temperature range; 3. (3) the Debye temperature is (581 ± 15) K; and 4. (4) the amplitude of thermal vibration of the barium atoms is anomalously high at all temperatures.

Metal—olefin bonding. The preparation and properties of group VI metal carbonyl complexes containing the ligands 1,6-bis(diphenylphosphino)- trans-hex-3-ene and 1,6-bis(diphenylarsino)- trans-hex-3-ene. The crystal and molecular x-ray structure of tricarbonyl-1,6-bis(diphenylphosphino)- trans-hex-3-enemolybdenum(0)

The complexes M(CO) 3(BDPH) and M(CO) 3(BDAH) (M  Cr, Mo or W, BDPH  1,6-bis(diphenylphosphino)- trans-hex-3-ene and BDAH  1,6-bis(diphenylarsino)- trans-hex-3-ene), have been prepared. These complexes have been characterised as octahedral complexes in which the tertiary unsaturated diphosphine and diarsine act as tridentate ligands. The complexes have been characterised by infrared, mass spectral, 1H nuclear magnetic resonance, 13C nuclear magnetic resonance and analytical data. The crystal structure of MO(CO) 3(BDPH) has been determined by conventional X-ray diffraction techniques. The straw-coloured needles are orthorhombic, space group Pbca, a 16.991(2), b 20.073(4), c 17.333(2) Å, Z  8. Refinement was by full-matrix least-squares methods and employed anisotropic thermal parameters for all non-hydrogen atoms. Hydrogen atoms were included in calculated positions but were not refined. The final residuals are R  0.048 and R w  0.048. The compound is monomeric. The unsaturated phosphine ligand is tridentate, through the two phosphorus atoms ( trans) and the olefin, and the octahedral coordination is completed by the three carbonyl groups. Distances and angles are MoP 2.450, 2.474(4) Å MOCO 2.03, 2.01(1) Å ( trans to CO) and 1.97(1) Å ( trans to CC). The olefin coordination has nearly symmetrical MoC, 2.504(12), 2.541(14) Å, a short olefin bond 1.38(2) Å, and a twisted olefin configuration.

Structure of cyclohexyl(4-pyridyl)methanol

CI2H17NO, M r = 191.27, monoclinic, P2~/c, a = 9 . 4 1 8 ( 2 ) , b = 1 1 . 4 3 3 ( 4 ) , c = 10.364 (3) A, f l = 101.55 (3) °, V = 1093.4 (6) t~3, Z = 4 , Dm= 1.16 (by flotation), D e = 1 .162 Mg m -3, / t (Mo Ka) = 0.0686 mm -~. R = 0.077 for 1077 observed reflections. The dihedral angle between the least-squares planes of the cyclohexyl ring, which is in a slightly distorted chair conformation, and the pyridine ring is 79.9 (2) °. There is no hydrogen bonding through the alcohol group. Introduction. Bispyridinium cyclohexylcarbonyl monooximes are compounds with antidotal properties in poisoning by highly toxic organophosphorus compounds (Deljac, Bregovec, Maksimovi6, Rakin, Markov, Radi6evi6 & Binenfeld, 1979). It seemed of interest to find out whether a correlation exists between the structure and physiological activity in this group of compounds. For this purpose structure analysis of cyclohexyl(4-pyridyl)methanol (Bregovec, Deljac & Binenfeld, 1979), one of the intermediates in the preparation of the related compounds, has been performed. Intensities were collected from a prismatic crystal on an automatic Enraf-Nonius CAD-4 diffractometer with graphite-monochromated Mo Ka radiation and the 09--20 scanning technique with a 20 scan width of (0.8 + 0.2 tan 0) ° and a variable scan rate. Intensities of 1924 reflections were measured up to sin 0/4 = 0.64 A -l, 1089 of which were above the 3tr level and used in the crystal-structure analysis. Absent reflections 0k0, k :/: 2n and hOl, l :/: 2n, confirmed the space group P2~/c. Corrections were made for Lorentz and polarization factors. The structure was solved by direct methods using the program MULTAN 80 (Main, Fiske, Hull, Lessinger, Germain, Declercq & Woolfson, 1980). All non-H atoms were obtained from the E 0567-7408/82/082275-03501.00 map calculated with the 256 largest E values (E > 1.43). All subsequent calculations were performed with the XRAY system (Stewart, 1976). Isotropic leastsquares refinement of the non-H atoms gave an R of 0.176. H atoms were located from a difference map and included in the refinement with fixed isotropic temperature factors U of the corresponding C atoms increased by 0.015 A 2 and an R of 0.135 was obtained. A full-matrix refinement with anisotropic thermal parameters for the non-H and isotropic (with fixed UH) for the H atoms, but varying separately the parameters of the non-H and H atoms, gave an R of 0.106. Inspection of the structure factors revealed that five strong low-order reflections were subject to extinction and seven others to experimental errors (451,661, 761, 3,62, i,11,2, ¢~73, 193 reflections with observed/calculated structure factors as follows: 2.8/15.1, 4 .5/ 24.2, 3.7/14.6, 1.8/7.6, 5.5/12.5, 3.3/10.5, 7.7/ 13.7). Continued refinement omitting these 12 reflections reduced R to 0.077.* An improvement was evident in the bond lengths and angles involving H atoms, while the positions of the non-H atoms were practically, unchanged. The scattering factors of Cromer & Mann (1968) were used for the non-H and those of Stewart, Davidson & Simpson (1965) for the H atoms. The final atomic coordinates are listed in Table 1. All parameter shifts of the non-H atoms in the final cycle were <0. la. Calculations were performed on a Univac 1110 computer, at the University Computing Centre, Zagreb. * Lists of structure factors and anisotropic thermal parameters have been deposited with the British Library Lending Division as Supplementary Publication No. SUP 36772 (13 pp.). Copies may be obtained through The Executive Secretary, International Union of Crystallography, 5 Abbey Square, Chester CH 1 2HU, England. © 1982 International Union of Crystallography 2276 C Y C L O H E X Y L ( 4 P Y R I D Y L ) M E T H A N O L Table 1. Fractional positional parameters (×104; ×103 for H) and equivalent isotropic temperature factors of the non-hydrogen atoms (× 102) computed by the expression Ueq= ~Y. l Y j Uua* a~ a i . a j The numbering of C atoms and their bonded H atoms is the same. Letters A and E denote axial and equatorial H atoms, respectively.

Structure of 1,2-O-(2,2,2-trichloroethylidene)-α-D-glucofuranose (α-D-chloralose)

CsHI1C1306, M r = 309.47, hexagonal , P32, a = 13.383 (3), c = 5.692 (2) A, V = 883.0 A 3, Z = 3, Dx = 1.746, D,, = 1.755 Mg m -a, ~(Mo Ka) = 0.71073 A, p ( M o Ka) = 0 .792 m m k The structure was solved by direct methods and refined to R(F) = 0.050 for 992 independent reflexions. The glucofuranose and dioxolane rings have aT 4 and °I2~E conformat ions , respectively, and these two rings are rigidly fused. The molecules are packed in a left-handed helix ar rangement along the c axis. The furanose-ring O atoms form intermolecular hydrogen bonds with the 0 ( 3 ) hydroxyl groups. The intermolecular hydrogen bonds between the 0 ( 5 ) and 0 ( 6 ) hydroxyl groups form right-handed double-helix chains around a threefold screw axis. C I . . . C I intermolecular contacts (3.45 A) were observed about another threefold screw axis. Introduction. a-D-Chloralose crystallized from an e thano l -wa te r solution at room temperature. A crystal with dimensions 0 .17 x 0 .20 x 0.33 mm was used to collect 1967 intensities of the hkl and h/~i reflexions by 09-20 scans to 0 = 50 ° on a Rigaku AFC-5 diffractometer. The structure was solved with M U L T A N (Main, Woolfson, Lessinger, Germain & Declercq, 1977), using 150 reflexions for phase generation. The first E map revealed all of the non-H atoms. The chemically known absolute structure was correctly given for space group P32 (two possible space groups, P31 and P3z, were indicated from the systematic absences 00l with l =~ 3n). The structure was refined by full-matrix least squares, minimizing } wlF o kFcI 2 with w l = t72(Fo) + (0.023Fo) 2 and where a(Fo) is the s tandard deviation of Fo from counting statistics. All H atoms were located from difference Fourier maps and refined isotropically. The final values of R = }'[F o klFcl[/~'lFol and g w = ( ~ w [ F o k l f c I [z/}'. ifolZ)l/Z were 0 .050 and 0.062, respectively, for 992 independent reflexions [F o > 3a(Fo)]. The atomic scattering factors for all a toms were obtained from International Tables for X-ray Crystallography (1974). All computa t ions were performed on a F A C O M M200 computer at the Data Processing Center, Kyo to University, using the KPAX program system. The atomic parameters are given in Tables 1 and 2.* * Lists of structure factors and anisotropic thermal parameters have been deposited with the British Library Lending Division as Supplementary Publication No. SUP 36731 (7 pp.). Copies may be obtained through The Executive Secretary, International Union of Crystallography, 5 Abbey Square, Chester CH 1 2HU, England. Table 1. Atomic coordinates for non-hydrogen atoms in a-D-chloralose Estimated standard deviations are given in parentheses. B~, is the isotropic equivalent of the anisotropic thermal parameters (Hamilton, 1959).

Synthesis, structure and reactions of a dihapto-formaldehyde complex, Os(η 2-CH 2O)(CO) 2(PPh 3) 2

Os(η 2-CH 2O)(CO) 2(PPh 3) 2 results from direct reaction of formaldehyde with the zerovalent complex, Os(CO) 2(PPh 3) 3. The structure of Os(η 2-CH 2O)(CO) 2(PPh 3) 2 was determined by X-ray crystallography. The crystals are triclinic, space group P 1 , a 18.739(2), b 11.157(1), c 9.986(1) Å, α 116.70(1), β 93.20(1), γ 107.93(1)°, V 1727.69 Å 3, Z = 2, D m 1.55(2), D c 1.57 g cm −3. Refinement of atomic parameters was by full-matrix least-squares methods, employing anisotropic thermal parameters for all non-hydrogen atoms except for the carbon atoms of the phenyl rings. The formaldehyde hydrogen atoms were located from difference electron density maps, other hydrogens were included in calculated positions. Final residuals were R = 0.047 and R w = 0.061 for 3508 unique observed reflections measured on an automatic diffractometer. The complex itself is monomeric, although interstices in the crystal lattice are occupied by hydrogen-bonded water dimers which fulfil a purely space-filling role. The osmium is bonded to two mutually trans triphenylphosphines, two carbonyls, and the η 5-formaldehyde, in an arrangement which is best described as distorted octahedral. The geometry of the coordinated formaldehyde is characterised by OsO 2.039(7), OsC 2.186(8) and CO 1.584(11) Å. The OsP bonds are equivalent at 2.372(2) and 2.378(2) Å but the OsCO bond trans to the formaldehyde carbon 1.931(7) Å is longer than that trans to the formaldehyde oxygen 1.907(7) Å. Os(η 2-CH 2O)(CO) 2(PPh 3) 3 has proved to be a useful synthetic precursor for stable formyl, hydroxymethyl, methoxymethyl, and halomethyl (CH 2X, X  Cl, Br, I) complexes. The compounds Os(CHO)H(CO) 2(PPh 3) 2, Os(CH 2OH)H(CO) 2(PPh 3) 2, Os(CH 2OMe)Cl(CO) 2(PPh 3) 2 and Os(CH 2Cl)Cl(CO) 2(PPh 3) 2 are illustrative of the many compounds which have been characterised. A general synthetic route to neutral formyl osmium complexes, Os(CHO)X(CO) 2(PPh 3) 2 (X = halide or alkyl) has been developed from reaction of the cations [OsX(CO) 3(PPh 3) 2] + with BH 4 −. Acetaldehyde also reacts with Os(CO) 2(PPh 3) 3 forming Os(η 1-C[O]CH 3)H(CO) 2(PPh 3) 2. No reaction was observed with benzaldehyde, and trichloroacetaldehyde affords the cation, [OsCl(CO) 2(PPh 3) 3] +.

The structure of 2,3,8,8a-tetrahydro-2-methyl-5,8a-diphenyl-1H-imidazo[2,1-c][1,4]thiazine

CI9H20N2 S, monoclinic, P21/n, a = 16.980 (4), b = 12.430 (1), c = 7.800 (2)/~, fl = 101.48 (2) ° , V = 1613.34/~ 3, Z = 4 and # = 0.152 mm-L The structure was solved by direct methods and refined by full-matrix least-squares methods to a conventional R value of 0.0859 for 1679 reflections. The H atoms were located geometrically and refined isotropically. All nonhydrogen atoms were allotted anisotropic thermal parameters. The S-C (sp 2) distance is 1.740 (9)/~ and S-C(sp 3) distance 1.798 (9)/~,. The C-S-C angle in the thiazine moiety is 97.6 (4) °. Introduction. The crystal structure determination of 2,3,8,8a-tetrahydro-2-methyl-5,8a-diphenyl- 1H-imi- dazo(2,1-c)(1,4)thiazine (TDIT) was undertaken after its structural study by ~3C NMR and IR spectroscopy (Sandhu, Tandon & Singh, 1980). The main interest of the crystal structure analysis was to confirm the formation of the imidazo(2,1-c)(1,4)thiazine because very little is known about the structure of this moiety. The title compound was obtained by the reaction of 2,2'-thiodiacetophenone with 1,2-diaminopropane. From spectroscopic data it was concluded that the structure can be either (I) or (II). The compound was obtained as elongated needles from an ethyl acetate/ petroleum ether mixture. Preliminary Weissenberg photographs indicated the crystal to be monoclinic, space group P2~/n.

THE CRYSTAL STRUCTURE AND MOLECULAR ABSOLUTE CONFIGURATION OF KOUMINE HYDROBROMIDE

The crystal structure of alkaloide, koumine Hydrobromide (C20H22N2O·HBr), has been solved by Patterson and Fourier methods and refined to an R value of 0.067 by full-matrix least-square method. The crystal belongs to orthorhombic system with the unit cell parameters: a = 14.307?, b = 12.053?, c = 9.862?; and four molecules are contained in the cell. The space group is P21 21 21. The positions of all hydrogen acoms have been found from a difference Fourier map calculated after the refinement of co-ordinates of all non-hydrogen atoms with anisotropic thermal parameters by least-squares method. The absolute configuration of the molecule has been established. The structural characteristics of the molecule were discussed.

Studies on the relationship between physico-chemical properties and crystalline forms of tulobuterol hydrochloride. II. Crystal structure analyses of the four crystalline forms of tulobuterol hydrochloride.

The crystal structures of the three forms (I, II, III) and the hydrate of tulobuterol hydrochloride (C-78) have been determined by X-ray analysis by using direct methods and refined by the block-diagonal least-squares method including anisotropic thermal parameters to final R values of 0.048, 0.057, 0.066 and 0.060 for forms, I, II, III and the hydrate, respectively. The molecular conformations in the four different crystalline forms are almost identical, though slight conformational differences are observed at the tertiary butyl terminal. The molecular packings however, are very different. Hydrogen bonds connecting the tulobuterol cations and the chloride anions form either a closed dimer-like unit in I and III or an open chain in II. In the hydrated crystal, a ribbon-like system of hydrogen bonds is formed by intervention of water molecules. Comparison of the crystal structures among these four forms of C-78 suggests a mechanism for the phase transition in the solid state and explains their thermodynamic properties previously reported.

Structural and dynamic properties of UO2at high temperatures

The authors present results of a dynamical simulation of UO2 at high temperatures. The calculations confirm the occurrence of superionic oxygen conduction, but find that the level of disorder on the anion superlattice is low. The results, however, suggest there are exceptionally large, anisotropic thermal parameters at high temperatures.

Structure of ferric pseudobactin, a siderophore from a plant growth promoting Pseudomonas.

Both plant growth promoting Pseudomonas B10 and its yellow-green, fluorescent iron transfer agent (siderophore) pseudobactin enhance the growth of the potato and control certain phytopathogenic microorganisms. The structure of the little compound has been determined by single-crystal X-ray diffraction methods using counter data. The structure consisted of a linear hexapeptide, L-Lys-D-threo-beta-OH-Asp-L-Ala-D-allo-Thr-L-Ala-D-N delta-OH-Orn, in which the N delta-OH nitrogen of the ornithine was cyclized with the C-terminal carboxyl group, and the N epsilon-amino group of the lysine was linked via an amide bond to a fluorescent quinoline derivative. The iron-chelating groups consisted of a hydroxamate group derived from N delta-hydroxyornithine, an alpha-hydroxy acid derived from beta-hydroxyaspartic acid, and an o-dihydroxy aromatic group derived from the quinoline moiety. The combination of metal-chelating ligands and the alternating L- and D-amino acids was unusual. The little compound crystallized as a single coordination isomer with the lambda absolute configuration. The present study is the first structural determination of a fluorescent siderophore. In the crystal structure, ferric pseudobactin formed a dimer, which constituted the asymmetric unit. The asymmetric unit also contained 26 water molecules. The molecules in the dimer were related by a pseudo-2-fold symmetry axis. Red-brown crystals of ferric pseudobactin (C42H57N12O16Fe . 13H2O), obtained from pyridine-acetic acid buffer solution equilibrated with water, conformed to space group I2 with a = 29.006 (23) A, b = 14.511 (13) A, c = 28.791 (21) A, and beta = 96.06 (5) degrees at -135 (2) degrees C. For eight molecules per unit cell, the calculated density was 1.38 g/cm3; the observed density was 1.40 g/cm3. The structure was refined by least-squares methods with anisotropic thermal parameters for all nonhydrogen atoms to a final R factor of 0.08 (8989 observed reflections).

The crystal structure of diiodo(( o-methylthiophenyl)diphenylphosphine)palladium(II), a complex exhibiting a large structural trans influence

The crystal structure of the title compound has been determined by conventional X-ray diffraction techniques. The red diamond-shaped crystals are monoclinic, space group P2 1/ n, a 8.914(4), b 16.090(12), c 14.991(5) Å, β 95.97(2)°, V 2138.44 Å 3, Z = 4. Refinement by full-matrix least-squares methods employed anisotropic thermal parameters for all non-hydrogen atoms and isotropic temperature factors for hydrogen atoms, and returned final residuals of R = 0.028 and R w = 0.028. The complex is monomeric, with a square planar coordination geometry comprising the S and P atoms of the bidentate ( o-methylthiophenyl)diphenylphosphine ligand and the two iodine atoms. The PdI distance trans to P is 2.658(1) Å whereas that trans to S is 2.602(1) Å. The difference of 56 standard deviations illustrates the greater structural trans influence of phosphine over thioether donors. The PdP and PdS distances of 2.250(2) and 2.288(2) Å, respectively, are normal. Two phenyl hydrogen atoms approach the Pd atom in the axial regions above and below the square plane at distances of 2.98 and 2.99 Å.

Synthesis and structure of an infinite-chain form of ZrI 2 (α)

The synthesis of a second polymorph of ZrI 2 has been achieved by a transport reaction between ZrI 4 and zirconium metal under a 750 850 ° C gradient in a sealed tantalum tube. The black lath-like crystals produced in the 775°C region occur in space group P2 1 m with a = 6.821(2) Å, b = 3.741(1) Å, c = 14.937(3) Å, β = 95.66(3)°, Z = 4. A total of 669 independent reflections with 2 θ ≤ 50° and I > 3 σ( I) were measured at room temperature on a four-circle automated diffractometer with monochromatized Mo Kα radiation and were corrected for absorption (μ = 190 cm −1). The structure was solved by direct methods and full-matrix least-squares refinement of all atoms with anisotropic thermal parameters to give final residuals R = 0.064 and R w = 0.079. This phase is isoelectronic and isostructural with β-MoTe 2, a distorted CdI 2-type structure in which the zirconium atoms are displaced 0.440 Å from the octahedral centers along a to form infinite zigzag metal chains ( d ZrZr = 3.182(3) Å) parallel to b. The phase is a diamagnetic semiconductor at room temperature ( E g ∼ 0.1 eV).

Solution and Solid State Studies of Tetrafluoro-7,7,8,8-Tetracyano-p-Quinodimethane, TCNQF4. Evidence for Long-Range Amphoteric Intermolecular Interactions and Low-Dimensionality in the Solid State Structure

Abstract Solution and solid state studies of TCNQF4 are reported. The electron affinity of TCNQF4 has been derived from spectral observations of the visible-near IR charge-transfer band for the pyrene complex and compared to that derived from the half-wave potentials used to characterize its reactivity in solution. It is demonstrated that the series, TCNQ, TCNQF to TCNQF4 shows a monotonic increase in reactivity with increasing fluorine substitution. Crystals of TCNQF4, grown from acetonitrile, are orthorhombic; space group Pbca, with the following crystal data: a = 14.678(7)A, b = 9.337(5)A, c = 8.174(2)A, V = 1120.0(6)A3, Z = 4 [based on a molecular weight for C12N4F4 = 276.22], Dmeasd = 1.65(1) g cm−3, Dcalcd = 1.64 g cm−3. Full matrix least-squares refinement (including anisotropic thermal parameters for all atoms) using 1763 counter-collected Fa's led to a final R value of 0.067 and a final weighted R value of 0.036. The observed molecular geometry of TCNQF4 is compared to that of its parent molecule TCNQ and to its monoanion found in some charge-transfer complexes. Crystal packing of TCNQF4 affords two interesting types of intermolecular acid/base (or donor/acceptor) interactions utilizing the cyano nitrogen atoms and the fluorinated carbon atoms of the quininoid ring. This subtle amphoterism exhibited by TCNQF4 leads to reduced dimensionality for the crystalline motif and is compared to similar solid state interactions found in several other molecules with π-bonded ring systems containing highly-electronegative substituents.

Structural study of iron carbonyl derivatives : V. Synthesis and crystal and molecular structure of μ-(SC 6H 5)-μ-(P(C 6H 5) 2)Fe 2(CO) 6

The title compound has been prepared by a new method and its crystal structure determined by a single-crystal X-ray study. The complex crystallizes in the orthorhombic space group Pna2 1, with a 16.544(1) », b 10.256(4) », c 28.76(1) » and Z = 8. Full-matrix least-squares refinement of positional and anisotropic thermal parameters of the 68 non-hydrogen atoms (H atoms were included and held fixed) of the two independent molecules, with 2172 reflections, led to R = 0.069 and R″ = 0.056. The compound has the usual structure of iron carbonyl derivatives with an Fe 2XX′ core. The FeFe mean bond length is 2.610(2) ». A comparison is made with similar derivatives having symmetric bridging systems Fe 2S 2 and Fe 2P 2.

Structure of lead bis(dihydrogenphosphate)

0.099. The seven shortest P b O distances are in the range 2 .44-2 .88 A. Hydrogen-bonded dimers form a three-dimensional network. I n t r o d u c t i o n . The investigation of the crystal structure of Pb(H2PO4)2 was performed as part of a study of acidic phosphates. To obtain crystals of Pb(H2PO4) 2, first Pb(HPO4) was prepared. PbCO3 was added to 50% H3PO 4 and heated at 353 K until a precipitate began to appear. The solution was then heated at 373 K to dissolve all PbCO3. On cooling, tiny plates of Pb(HPO4) crystallized. The precipitate was washed with water, dried and dissolved in 96% H3PO 4 at 453 K. By cooling slowly, prismatic needles of Pb(H2PO4)2 were obtained. The crystals are sensitive to moisture. The excess of H3PO 4 is difficult to wash out. Treatment with ether, as recommended by Mellor (1947), has no appreciable effect on the stability of the crystals. For all crystallographic measurements, crystals sealed in Lindemann-glass capillaries were used. Preliminary Weissenberg photographs indicated triclinic symmetry. A crystal of dimensions 0.09 x 0.14 x 0.28 mm was mounted on a Syntex P i diffractometer. Cell parameters were determined by least squares from 20 values for 14 strong general reflexions. The intensity measurements were made by the m-scan technique, using graphite-monochromated Mo K a radiation. Intensities of 1730 reflexions in the sphere 0 3o(1) were used in the subsequent analyses. In the absence of a suitable program no absorption correction was applied. The structure was solved by the heavy-atom method. Isotropic refinement of the nonhydrogen atoms terminated at R = 0.136. Refinement with anisotropic thermal parameters for Pb led to a non-definite value for the vibrational tensor. The least-squares refinement in space group P1 was unsuccessful. At that stage of 0567-7408/81/030660-03501.00 Table 1. Fractional coordinates (x 105 for Pb, x 104 for P, O) and thermal parameters

The crystal structure of 8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(I)

The crystal structure of 8-hydroxyquinolinatocarbonyltriphenylphosphine, C 28H 21O 2NPRh, was determined from 2995 unique observed reflections obtained with a computer automated diffractometer. The unit cell is triclinic with a = 14.154 Å, b = 9.984 Å, c = 9.409 Å, α = 116.16°, β = 90.09°, γ = 99.60°, Z = 2 with space group P 1 . Refinement of the data with anisotropic thermal parameters converged to R = 4.9%. The compound was prepared by the reaction between [Rh(oxine)(Co) 2] and triphenylphosphine. The structure determination shows that the carbonyl group trans to the nitrogen atom of the 8-hydroxyquinolinato ligand was substituted by the triphenylphosphine ligand, which indicate that the nitrogen atom of the chelate ring has a larger trans influence than the oxygen atom.

Crystal structure of tris(glycine)calcium(II)diiodide monohydrate

Tris(glycine)calcium(II)diiodide monohydrate, (NH 2CH 2COOH) 3 CaI 2·H 2O, crystallises in a tetra-molecular monoclinic unit cell of dimensions a = 12.069(8), b = 7.374(13), C = 19.129(21) A ̊ and β = 109°36(8)′, in the space group P 1/ c. The crystal structure has been elucidated using the three-dimensional Patterson synthesis for locating the heavy atoms, and successive Fourier syntheses for the location of the light atoms, with 1229 visually estimated photographically recorded reflections. With anisotropic thermal parameters for the calcium and iodine atoms and isotropic thermal parameters for the other non-hydrogen atoms, the final R factor is 0.102. The calcium atom is coordinated to seven oxygen atoms—five from the glycine molecules and two from water molecules— forming a distorted pentagonal bipyramid. One of the glycine molecules links the adjacent CaO polyhedra. Iodine atoms do not take part in calcium coordination. A hydrogen bonding scheme has been proposed on the basis of interatomic distances in the structure.

1-{1-[4-(4-Fluorophenyl)-4-oxobutyl]-1,2,3,6-tetrahydro-4-pyridyl}-1,3-dihydro-2H-benzimidazol-2-one dihydrate (Dehydrobenzperidol®)

C=H=FN302.2H20 , M~ = 415.45, mono- clinic, P21/n, a = 9.693(2), b = 10.811 (3), c = 20-442 (5) /k, fl= 79.16(2) ° , V= 2104 (1) /k3, Dm = 1.32, D = 1.31 Mg m --~, Z = 4, 2(Cu K-) = 1.5418 X, /J(Cu Ka) = 0.82 mm-~; F(000) = 880, final conventional R = 6.2% for 1421 reflections with (sin 0/2),,,,~ = 0.459/k -~. Owing to the presence of two water molecules an extensive network of hydrogen bonds is formed. Introduction. The title compound, also called droperidol, is a potent neuroleptic. Crystals were grown at room temperature by slow evaporation from a water-methanol solution. The cell dimensions were obtained from a least- squares fit to the setting angles of 23 reflections. Intensity measurements were made on a Syntex P2~ diffractometer with graphite-monochromated Cu Ka radiation. During the collection of data, three reference reflections (measured every 50 reflections) showed a nearly linear intensity decrease of approximately 30% with time (0-20 scan technique). Intensities were measured for all independent reflections (1912) with 20 3-0o(I,~L)I and used in the refinement. The data were corrected for Lorentz-polarization effects, but not for absorption. The structure was solved by direct methods using MULTAN (Main, Woolfson, Lessinger, Germain & Declercq, 1974). All non-hydrogen atoms were located in the resultant E map. Refinement of the positional and anisotropic thermal parameters of the 17 non- hydrogen atoms by block-diagonal least-squares methods (CRYLSQ link of the XRAY system; Stewart, Machin, Dickinson, Ammon, Heck & Flack, 1976) resulted in R = 9-7%. The H atoms were then located from a difference synthesis and were included as a fixed-atom contribution with the overall tempera- ture factor. Further refinement converged at R =

X-Ray Structural Study of Ferroelectric Cesium Dihydrogen Phosphate at Room Temperature

The atomic coordinates and the anisotropic thermal parameters of CsH 2 PO 4 crystal in the paraelectric phase have been obtained using three-dimensional X-ray intensity data collected by a four-circle automatic diffractometer at room temperature. The structure is refined to R =0.029 for 780 independent reflections. Two types of hydrogen bonds are clearly distinguished in the electron density maps which display distributions corresponding to order and disorder of protons, respectively.