Crystal structure of tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionato) aquolutetium(III)—Lu(fod)3. H2O

The crystal structure of Lu(fod)₃. H₂O has been solved by three-dimensional X-ray methods at room temperature. The space group isP and the cell dimensions area = 16·392,b = 22·492,c = 13·366 Å, = 91·83 °, = 119·93 °, = 90·00 °. There are four formula-units per unit cell;D _m = 1·66,D _c = 1·667 g cm^–3. Least-squares refinement of atomic and individual isotropic thermal parameters terminated withR = 0·128. This relatively highR factor is due to crystal decomposition, to the prohibitively large asymmetric unit which necessitated refinement in parts and also to the high vapour pressure of the compound and consequently large thermal vibrations in the structure. These factors caused large uncertainties especially in the positions of the atoms at the ends of the long side chains, but the more important geometry of the coordination polyhedra at the cores of the roughly spherical molecules have been firmly established. Except for orientation differences, the two crystallographically independent formula-units are very similar and both are dimerized through water molecules with hydrogen bonds across centres of symmetry. In each case the coordination of lutetium is seven-fold, with the geometry of a monocapped trigonal prism.     

Determination and correlation of heavy atom positions in the derivatives used in the X-ray analysis of ribonuclease A at 2.5 Å resolution

The analysis of four heavy atom derivatives of ribonuclease A is described leading to isomorphous phasing at 2.5 resolution. Differences in the characteristics of the derivatives are discussed with respect to the determination of their heavy atom parameters and the correlation of sites between derivatives to produce a self consistent set. The criteria used to ensure consistency are described. In the final phase analysis using refined heavy atom parameters the least squaresR factors of the derivatives were .124, .143, .101, and .067 respectively, and the mean figure of merit for the 3444 observed reflexions was 0.66.In recognition of C. H. Carlisle's pioneering work in this field.     

Tilting structures in perovskites

Thirty five low-symmetry tilting phases of the octahedra in which the atoms located at the initial octahedral position remain equivalent are derived for the perovskite structure at the k₁₀(X), k₁₁(M), and k₁₃(R) points of the Brillouin zone. For each low-symmetry phase, structural data are presented and a relationship between the atomic displacements and the order parameters is deduced. All the low-symmetry phases can be obtained by considering only one or two order parameters.     

Neutron diffraction investigation of the hydrogen positions in the crystal structure of monetite,CaHPO4

An occupation-factor analysis using single-crystal neutron diffraction data has shown that the hydrogen atoms in the structure of the mineral monetite, CaHPO₄, occupy hydrogen-bonding sites closely similar to those predicted in a previous X-ray refinement. Least-squares refinement in space groupP¯1 of the potential coordinates and isotropic temperature parameters for the three distinct proton sites led to a resultantR of 0·10 over the 371 independent neutron structure factors. Detailed analysis showed that the distribution of the hydrogen atoms was almost certainly ordered in symmetryP1 with only half of the O(6) atoms (in space groupP¯1) carrying hydrogen atoms; the short O(7)-P(1)... O(7) hydrogen bond of 2·44 Å across what would be a symmetry centre inP¯1 is probably unsymmetrical. Minute piezo- and pyroelectric effects confirmedP1 as the space group. Further refinement of the X-ray data in space groupP1 indicated that the deviations from centrosymmetry must be small and, so far as can be detected, confined to the hydrogen atoms.We thank Mr James R. Lehr for the crystal, Prof. W. G. Perdok for the piezoelectric measurement, and Dr. G. Ferraris for a useful discussion. We are also grateful to Mr. D. H. C. Harris and the staff of the University Support Group for help at AERE, and to the S.R.C. for providing access to neutron and computational facilities and for financial support to WAD.     

Crystal structure of 5α-bromo-8β,9α-dimethyl-hydrindane-1,4-dione

The molecular structure of 5-bromo-8,9-dimethylhydrindane-1,4-dione (C₁₁H₁₅BrO₂) has been confirmed using three-dimensional X-ray data collected by means of a Picker FACS-1 four-circle diffractometer. The compound crystallized in the space groupC2/c with unit cell constantsa = 26.56(5),b = 6.68(1),c = 12.32(2) Å and = 90.6(1) °; the density was 1.55 g cm^–3 andZ = 8. Least-squares refinement of the positional and anistropic thermal parameters gave a finalR ₁ value of 0.083 for 793 significant reflections.     

Structural study of hexacarbonyldi-μ-mercaptobenzothiazolato(μS,N) dimanganese

The structure of hexacarbonyldi--mercaptobenzothiazolato(S,N)dimanganese, [Mn(CO)₃mbt]₂, has been solved using three-dimensional X-ray data. The compound crystallizes in the space groupC2/c, with unit-cell constantsa = 14.38(2),b = 11.84(2),c = 13.90(2) Å, and = 94.70(8) °. Least-squares refinement of the positional and anisotropic thermal parameters gives a finalR value of 0.048 for 2090 independent reflections. The results are compared with those obtained with the previously reported isomorphous complex of rhenium, and the structural arrangement is discussed in terms of metalic corrosion inhibition.Equipe de Recherche Associée au C.N.R.S. No 608     

An experimental charge density study of mesulergine hydrochloride,a dopamine agonist

Carefully measured high-resolution X-ray diffraction measurements at 120(2) K have been used to map the electron deformation density of mesulergine hydrochloride, a dopamine agonist. A total of 52,508 intensities were measured with MoK radiation to a sin/)_max = 0.84~Å^–1. Averaging symmetry equivalent reflections yielded 9,418 unique reflections. A least squares refinement procedure was used in which multipole parameters were added to describe the distortions of the atomic electron distributions from spherical symmetry. Maps of the model electron deformation density distribution show the distribution of electron density in mesulergine hydrochloride. Molecular electrostatic potentials have been calculated from the electron densities determined in the least-squares multipole refinement. A region of negative electrostatic potential near N23 in the NHSO₂N(CH₃)₂ substituent suggests that the nitrogen atom would be reactive toward electrophilic attack. Net atomic charges calculated from refined monopole population parameters yielded charges of +0.17 for the NHSO₂N(CH₃)₂ substituent and +0.37 for the ergoline fused ring system. There does not seem to be an area of the molecule that, based on the results of this study, is more electron rich or electron deficient than others. Crystallographic data: C₁₈H₂₆N₄O₂SHCl, P2₁, a = 12.1281(3) Å, b = 6.1357(4) Å, c = 13.5935(4) Å, = 105.14(5), V = 974.14(5) ų, Z = 2.     

Crystal and molecular structure of N-methyl-8-fluoroquinolinium chloride,C10H9NFCl·H2O

The crystal structure ofN-methyl-8-fluoroquinolinium chloride was determined by single crystal X-ray diffraction with refinement by full-matrix least-squares techniques. The crystals belong to theP2₁/n space group with unit cell parametersa=6.938(3),b=7.855(4),c=18.592(14) Å, and =94.72(4)°. The calculated and observed densities are 1.415(6) and 1.421 g cm^–3, respectively. Isotropie refinement of hydrogens and anisotropic refinement of all other atoms with 1040 unique reflections havingI>3(I) converged withR ₁=0.055 andR ₂=0.060. Steric interactions between the fluorine and the methyl group are evident from the structural data, but the planarity of the quinolinium ring is not significantly distorted.     

C(4) helices,Br⋅<Emphasis Type="Italic">s</Emphasis>Br interaction and <Emphasis Type="Italic">R</Emphasis><Stack><Subscript>4</Subscript><Superscript>2</Superscript></Stack> (10) ring in bromoipriflavone

The title compound, 8-bromo-7-isopropoxyisoflavone (bromoipriflavone), C₁₈H₁₅O₃Br, crystallizes in tetragonal crystal system, space group I4₁/a with cell constants a = 21.396(2) Å, c = 13.588(2) Å, V = 6220.2(14) ų and Z = 16. Bromoipriflavone is composed of a benzopyranone moiety, a phenyl moiety, an isopropoxy group and a bromine atom. The benzopyranone ring is not coplanar with the phenyl ring with a dihedral angle of 55.1. The molecules are stacked into a C(4) helices down [001] via – stacking and hydrogen bonds, the C(4) helices are assembled into three-dimensional network via strong BrsBr interactions and synthons R₄²(10) formed by two tri-centered C–HsO hydrogen bonds, resulting in a distinctive high-symmetry supramolecule. The title compound was also characterized by IR and ¹H NMR.     

Synthesis,crystal and molecular structure,and spectroscopic properties of manganese(II) bis(2,5-diamino-1,3,4-thiadiazole) diaqua dichloride

The reaction product of manganese(II) chloride and 2,5-diamino-1,3,4-thiadiazole was prepared and characterized by means of structural, and spectroscopic measurements. The crystals are monoclinic, space groupC2/c, witha=12.403(4),b=10.742(2),c=10.449(5)Å,=92.61(3)°, andZ=4. The structure was solved by the heavy-atom method, and least-squares refinement of structural parameters led to a conventionalR factor of 0.020 for 1518 independent reflections. The structure consists of discrete molecules with twofold symmetry in which the manganese atom is coordinated in slightly distorted octahedral geometry by two nitrogen, two oxygen and two chlorine atoms.     

Crystal and molecular structure of inner-chelatecis-1,7-dioxa-4,10-diazacyclododecane-4,10-diacetatocopper(II) dihydrate

cis-1,7-Dioxa-4,10-diazacyclododecane-4,10-diacetato-copper(II) dihydrate crystallizes in the monoclinic space groupP2₁/n witha=11.318(2),b=12.129(2),c=12.160(2) Å,=110.09(1)°, andZ=4. The structure was solved by the heavy-atom technique, followed by full-matrix least-squares refinement with anisotropic thermal parameters for non-H atoms. The Cu(II) atom is in a very distorted octahedral environment, with two nitrogen and two oxygen atoms located approximately coplanar with Cu(II), and the two remaining oxygen atoms in apical positions forming an angle of about 147° at Cu(II). The 12-membered ring has noncrystallographicmm2 symmetry. Two five-membered rings containing acetato groups are located in acis arrangement relative to the macrocyclic ring.     

Crystal structures of p-chloro- and p-bromobenzaldehyde

p-Chloro- and p-bromobenzaldehyde form isomorphous monoclinic crystals, space groupP2 ₁/a. For p-Cl at –96°C,a=12.945(3),b=3.833(3),c=26.503(9) Å, =103.68(2)°,Z=8,V=1278(2) ų,Dx=1.461(2) g cm^–3, refinement on 2714 reflections,R=0.047. For p-Br at –96°C,a=12.754(5),b=3.919(3),c=27.317(12) Å, =103.28(3)°,Z=8,V=1329(2) ų,Dx=1.849(3) g cm^–3, refinement on 1519 reflections,R=0.062. The molecules do not differ significantly from planarity. They pack in stacks with Cl...Cl or Br...Br contacts at one end and CH...O contacts that are suggestive of hydrogen bonds at the other. There are no O...Cl or O...Br contacts.     

Structural study of K<Subscript>0.93</Subscript>Ti<Subscript>0.93</Subscript>Nb<Subscript>0.07</Subscript>OPO<Subscript>4</Subscript> single crystals at 30 K

The structure of a K_0.93Ti_0.93Nb_0.07OPO₄ single crystal is studied at the temperature 30 K. The measurements are performed on a four-circle HUBER-5042 diffractometer with a DISPLEX DE-202 cryostat. Processing of the diffraction data and the preliminary refinement of the model are performed using the ASTRA program package. The final refinement of the structure model is made using the JANA2000 program complex. The refinement shows that the structure of a K_0.93Ti_0.93Nb_0.07OPO₄ crystal at T = 30 K is similar to its structure at room temperature. No phase transitions are revealed. Slight temperature-induced displacements of the potassium positions in the large cavities of the mixed framework are established.     

Structural studies of oxalohydroxamic acid by single crystal X-ray diffraction and spectroscopic methods

The structure of oxalohydroxamic acid has been investigated by X-ray and spectroscopic analyses. It has been shown that oxalohydroxamic acid exists in the oxamic form in the solid as well as in solution. The variable-temperature nuclear magnetic resonance (NMR) studies reveal an exchange of OH and NH protons, the exchange being faster at higher temperatures. The kinetic and the thermodynamic parameters such as the rate constant (K), the free energy of activation (G ^DG), and the energy of activation (E _a) for the exchange process have been obtained. The compound crystallizes in the monoclinic space groupP2₁/c witha=5.208,b=3.864,c=11.482 Å,=111.45°, andZ=2. The structure was solved withMultan 80. The refinement by block diagonal least squares and Fourier methods providedR=0.035. There is strong hydrogen bonding between the molecules which form dimer.     

Crystal and molecular structure of tris (2,2,6,6-tetramethyl-3,5-heptanedionato) aquodysprosium(III), Dy(thd)3H2O

The crystal structure of Dy(thd)₃H₂O has been solved by three-dimensional X-ray methods at room temperature. The space group isP¯1 and the cell dimensions area = 14·21(1),b = 14·88(2),c = 11·60(2) Å, = 99·76(3), = 109·91(1), = 114·08(1) °.Z = 2,D _m = l·24 andD _x = 1·238 gcm^–3, respectively. Full-matrix least-squares refinement of atomic and individual isotropic thermal parameters, using 3015 intensities obtained by counter methods, terminated with a conventionalR of 0·058. The oxygen polyhedron around dysprosium has pure seven-coordination geometry, the seventh ligand being the water molecule. The water is hydrogen bonded to two oxygen atoms of a centre of symmetry related formula unit so that two formula units are in fact held together by hydrogen bonds in a dimer.Supported by National Institute for Metallurgy, Johannesburg.     

Crystal and molecular structure of chloro(tri-t-butylphosphino-C,P)triphenylarsinepalladium(II)

(SP-4-4)-chloro[2-(di-tert-butylphosphino)-2-methylpropyl-C,P] (triphenylarsine)palladium(II), C₃₀H₄₁ClPAsPd, has been characterized by single-crystal X-ray diffraction data. It crystallizes in the monoclinic space groupP2₁ witha=9.611(2),b=14.335(2),C=11.953(1) Å,=111.97(1)° andZ=2. The phasing model was determined by direct methods and the full-matrix least-squares refinement of 302 structural parameters yielded a reliability factor of 0.039 for 2269 unique reflections withI> 3(I). The square planar geometry about the Pd atom is angularly distorted due to the steric bulk of the ligands and the formation of the four-membered ring, Pd-P-C(2)-C(1), which is severely distorted. The arsine and phosphine ligands are orientedtrans across the square-planar geometry with an As-Pd-P angle of 163.5(1)°. Details of the structural content and selected bond lengths and angles are discussed. The phenyl rings are planar and in a staggered orientation. Steric bulk illustrations from ligand profile calculations (/2 vs ) about the arsine and phosphine ligands are presented.     

Crystal structure ofβ-C.I. Solvent Yellow 18, 4(2′,4′-dimethylphenyl hydrazono)-5-methyl-2-phenyl-3H-pyrazol-3-one

The crystal structure of-C.I. Solvent Yellow 18, C₁₈H₁₈N₄O, has been determined by single crystal X-ray diffraction techniques. It crystallizes in the monoclinic system witha=30.948(18)Å,b=4.918(4)Å,c=20.861(9)Å,=91.68(4)°, space groupC2/c,Z=8. The structure has been solved by direct methods and least-squares refinement has been completed on three dimensional data (1237 reflections MoK radiation). The hydrogen atoms have been found but only their positional parameters refined. Final residual 0.092 (all intensity data). The molecule exists as the hydrazone tautomer and intramolecular hydrogen bonding keeps the molecule approximately planar. The molecules are packed in columns parallel to theb axis, while the molecule lies approximately parallel to the (51¯3) plane. The molecules are linked by van der Waals' force.     

Crystal and molecular structure of 1,1′,3,3′-tetraphenyloxaldiamidrazone

1,1,3,3-Tetraphenyloxaldiamidrazone, C₂₆H₂₄N₆, crystallizes in the monoclinic system: space groupP2₁/c,a= 13.946(1) Å,b= 5.706(1) Å,c= 17.109(1) Å, = 125.31(1) °,D _m = 1.254,D _c = 1.259 gcm^–3 andZ= 2. Intensities were obtained from –2 scans with a Syntex automated diffractometer using graphite-monochromated MoK radiation. The structure was solved by direct methods. Full-matrix least-squares refinement of all positional and thermal (anisotropic for the nonhydrogen atoms and isotropic for the hydrogen atoms) parameters using 2022 reflections [I>2(itI)] converged at a conventionalR of 0.041. The molecule is characterized by a conjugated pi system which includes the central N=C–C=N moiety and two of the four aniline groups. No intermolecular and only weak intramolecular hydrogen bonds are present.     

Crystal and molecular structure of di-μ-chlorobis[2-[[[(2-hydroxy-1-naphthyl)methyl]imino]-ethanolato]N,O,O′]di-copper(II) hemihydrate

The structure of the title compound [Cu₂Cl₂(C₁₃H₁₂NO₂)₂]·1/2 H₂O has been determined from single crystal X-ray diffraction data by direct methods. Full-matrix least-squares refinement of the structural parameters led to conventionalR factor of 0.037 for 4367 intensities above 3(I). The compound forms a dinuclear complex with distorted tetragonal-pyramidal geometry at each copper center. The unsymmetrical dimers are formed by weak axial coordination to one copper center by chloride ligands which are in the base plane of the adjacent copper atom. The apical Cu1-C12 and Cu2-C11 distances are 2.788(1) and 3.130(1) Å, respectively. The Cu1-Cu2 separation is 3.4995(3) Å in the dimers. A disorder of one five-membered chelate ring has been observed. Two alternative positionsa andb of the C26 atom were found and refined with constrained bond lengths. The geometry of the ligand and hydrogen bonds is discussed.     

Crystal and molecular structure of CI Solvent Yellow 18, 4-(2′,4′-dimethyl phenyl hydrazono)-5-methyl-2-phenyl-3H-pyrazol-3-one

The crystal structure of CI Solvent Yellow 18, C₁₈H₁₈N₄O, has been determined by single crystal X-ray diffraction techniques. It crystallizes in the monoclinic system witha=7.480(2) Å,b=19.184(3) Å,c=11.260(1) Å,=98.00(3)°, space groupP2₁/n andZ=4. The structure has been solved by direct methods, and least-squares refinement has been completed on three-dimensional data (2310 reflections, CuK radiation). The hydrogen atoms have been found, but only their positional parameters refined. Final residual 0.085 (all positive intensity data). The molecule exists as the hydrazone tautomer and intramolecular hydrogen bonding keep the molecule approximately planar. The molecules are packed in layers parallel to the (¯202) plane and in columns parallel tob. Alternate molecules within the columns are in antiparallel. The molecules are linked by van der Waals' forces.