An X-ray and 13C CP/MAS NMR study of C,C-linked bipyrazoles and bispyrazolylmethanes

4,4′-Methylene-bispyrazole (1) crystallizes in the P2₁/n space group with Z = 4, a = 5.4199(8) Å, b = 16.194(6) Å, c = 8.381(5) Å, β = 98.18(5)°. 4,4′-Methylene-bis (3,5-dimethylpyrazole) (2) crystallizes in the Pbca space group with Z = 8, a = 8.350(3) Å, b = 16.078(3) Å and c = 17.154(5) Å. Finally, 3,3′-bipyrazole (4) crystallizes in the P2₁/n space group with Z = 2, a = 5.465(2) Å, b = 5.491(3) Å, c = 10.058(4) Å and sol; = 92.88(2)°. The packing adopted by molecules 1 and 2 is related to the disposition of the pyrazole rings. In compound 4, all the molecules are joined to their neighbors by two double hydrogen bond systems forming zigzag chains. Using solid state ¹³C NMR spectroscopy, no dynamic proton transfer was observed in these crystals, and not on those of 3,5,3′,5′-tetramethyl-4,4′-bipyrazole (3) either.     

Crystal structures of ruthenium(III) cis- and trans-trifluoroacetylacetonate

Single crystal X-ray diffraction analysis is used to determine the structures of ruthenium(III) cis and trans trifluoroacetylacetonate at a temperature of 150 K. The crystallographic data for cis-C₁₅H₁₂F₉O₆Ru are: a = 8.6562(3) Å, b = 12.6941(3) Å, c= 17.8776(5) Å, β = 93.129(1)°, P2₁/n space group, V = 1961.51(10) ų, Z = 4, d _x =1.897 g/cm³, R = 0.0565. For trans C₁₅H₁₂F₉O₆Ru they are: a = 13.4060(3) Å, b = 14.5946(3) Å, c = 20.1316(4) Å, Pcab space group, V = 3938.85(14) ų, Z = 8, d _x = 1.890 g/cm³, R = 0.0840. Both structures are molecular and built of neutral molecules; the metal atom coordinates six atoms of oxygen of three ligands of β-diketone. The R—O distances in cis Ru(tfac)₃ lie between 1.99 Å and 2.03 Å; in trans Ru(tfac)₃, 1.99 Å and 2.02 Å. The molecules in the crystal are bonded only by van der Waals interactions; in the structures of the cis and trans forms, the six shortest Ru…Ru distances lie within the limits of 7.601-8.656 Å and 7.326–7.714 Å respectively.     

The structures of fluorides X. Neutron powder diffraction profile studies of UF6 at 193°K and 293°K

Neutron diffraction studies on polycrystalline UF₆ have been carried out at 193°K and 293°K. At both temperatures, UF₆ is orthorhombic with the space group Pnma (D¹⁶_2h) and Z = 4. Measured lattice parameters are a = 9.924 (10) Å, b = 8.954 (9) Å, c = 5.198 (5)Å at 293°K and a = 9.843 (11), b = 8.920 (10), c = 5.173 (6) Å at 193°K. The neutron diffraction patterns were analyzed by the least-squares profile-fitting technique. The final values of $\text{R =}\text{∑}\text{i}\text{(|I}{}_{\mathrm{<mtext>o</mtext><mtext>i</mtext>}}\text{? I}{}_{\mathrm{<mtext>o</mtext><mtext>i</mtext>}}\text{|)/∑ I}{}_{\mathrm{<mtext>o</mtext><mtext>i</mtext>}}$ over the pattern points, where I_oi is a background corrected measured intensity, were 0.081 at 193°K and 0.133 at 293°K.On cooling, the hexagonal close-packing tends to become more regular, and the FF distances external to a UF₆ octahedron contract. The octahedra are nearly regular with a mean UF distance of 1.98 Å, a mean FF edge of 2.80 Å, and a FUF angle of 90.0° at 193°K.     

Crystal structures of aroylhydrazones derived from 5-methoxysalicylaldehyde

Two new aroylhydrazones 3-bromo-N′-(2-hydroxy-5-methoxybenzylidene)benzohydrazide (1) and 4-hydroxy-3-methoxy-N′-(2-hydroxy-5-methoxybenzylidene)benzohydrazide (2), derived from 5-methoxysalicylaldehyde, are prepared and determined by means of infrared and ¹H NMR spectroscopy and single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group P2₁/n with a = 5.9406(7) Å, b = 31.833(3) Å, c = 7.6460(8) Å, β = 94.522(4)°, V = 1441.4(3) ų, Z = 4. Compound 2 crystallizes in the monoclinic space group P2₁/c with a = 14.3471(9) Å, b = 11.3893(7) Å, c = 9.6853(6) Å, β = 94.063(2)°, V = 1578.6(2) ų, Z = 4. Both molecules have very similar bond lengths and angles. The crystal structures of both compounds are stabilized by N-H...O and O-H...O hydrogen bonds as well as π...π interactions.     

Synthesis and Crystal Structures of Tris-[3, 5-bis(trifluoromethyl)phenyl]arsine Oxide at 293 and 100 K and the Localization of the Trifluoromethyl Groups

Tris[3, 5-bis(trifluoromethyl)phenyl]arsine oxide ( 1 ) was synthesised by oxidation of tris[3, 5-bis(trifluoromethyl)phenyl]arsine with hydrogen peroxide in acetone. At 293 K, it crystallizes in the trigonal space group R3c (a = 20.2947(12) Å, c = 11.2484(13) Å, Z = 6, R₁ = 0.0254). The compound undergoes a phase transition upon cooling, and it crystallizes in the monoclinic space group Cc at 100 K (a = 13.8621(13) Å, b = 18.6537(17) Å, c = 11.2874(10) Å, Z = 4, R₁ = 0.0444). The crystal structures of both phases were determined. The fluorine atoms of the trifluoromethyl groups are strongly disordered at room temperature, which probably indicates a rotational motion in the plane of the fluorine atoms. This motion slows down while lowering the temperature, and the fluorine atoms are localized at 100 K. This point is illustrated by comparison of the experimental electron densities at the CF₃ groups. The packing pattern in both structures consists of parallel columns of ecliptically stacked molecules. The columns are hexagonally arranged.     

Thiourea-halide lattices. Part 1. Crystal structures of (n-C4H9)4N+F−·3(NH2)2CS, (n-C4H9)3(CH3) N+X−·2(NH2)2CS (X = Cl,Br), and (n-C3H7)4N+I−·(NH2)2CS

The title complexes (1, X = F;2, X = C 1; 3, X = Br and isomorphous with2; 4, X = I) have been prepared and characterized by X-ray crystallography. Crystal data, MoKα radiation:1, space groupCc,Z =4,a = 12.017(3),b = 14.263(5),c = 17.210(7) Å,β = 103.06(2)°, andR _F =0.053 for 2044 observed data;2, space groupCc,Z = 4,a = 12.817(3),b = 11.072(2),c = 16.781(5) Å,β =90.74(2)°,R _F = 0.044 for 2249 data;3,a = 12.873(4),b = 11. 119(2),c = 16.957(2) Å,β = 89.11(2)°,R _F = 0.049 for 2059 data;4, space groupP2₁/n,Z = 4,a = 8.858(2),b = 14.358(3),c = 15.379(3) Å,β = 93.88(1)°,R _F = 0.068 for 3119 data. In all four structures each thiourea molecule interacts with adjacent thiourea molecules via N-H ... S hydrogen bonds to give a ribbon-like arrangement, and also forms a pair of ‘chelating’ N-H ... X hydrogen bonds with a halide ion, resulting in an anionic framework (in1–3) or composite ribbon (in4) as a component in the crystal packing. The measured ranges of N... X distances are: 2.819(5)-2.994(7) Å for1, 3.252(3)-3.291(3)Å for 2, 3.353(6)-3.459(6)Å for3, and 3.564(5)-3.680(5) Å for 4.     

Crystal structures of condensation products of 3,5-dibromosalicylic aldehyde with streptocide, norsulfazole, and ethazole

Crystal structures of 4-[(3,5-dibromo-2-hydroxy-benzylidene)-amino]-benzenesulfonamide (I), 4-[(3,5-dibromo-2-hydroxy-benzylidene)-amino]-N-thiazol-2-yl-benzenesulfonamide (II), and 4-[((3,5-dibromo-2-hydroxy-benzylidene)-amino]-N-(5-ethyl-1,3,4-thiadiazol-2-yl)-benzenesulfonamide (III) have been determined. The crystals of I are monoclinic, a = 8.645(2) Å, b = 12.622(3) Å, c = 14.414(3) Å; β = 104.31(3)°, space group P2₁/n, Z = 4, R = 0.0642. The crystals of II are also monoclinic, a = 10.313(2) Å, b = 11.288(2) Å, c = 15.766(3) Å; α = 99.37(3)°, space group P2₁/c, Z = 4, R = 0.0635. The crystals of III are triclinic, a = 10.567(2) Å, b = 10.849(2) Å, c = 18.432(4) Å; α = 75.97(3)°, β = 89.71(3)°, γ = 87.33(3)°, space group P-1, Z = 4, R = 0.0644. The asymmetric part of the unit cell of compounds I and II contains a single molecule of the Schiff’s base, while in III two independent azomethine molecules A and B. The studied compounds I–III adopt the E-configuration relatively to the double azomethine bond C=N. Owing to phenolic oxygen together with nitrogen and oxygen atoms of the sulfonamide group, compound I makes in a crystalline state a two-dimensional hydrogen bonded network parallel to the plane (1 0 1). Compound II forms centrosymmetric dimers in the crystals via N-H…N hydrogen bonds. These dimers, in their turn, are connected by hydrogen bonds O-H…O into infinite chains running along the double screw axis b. As in II, molecules and of compound III form centrosymmetric dimers through hydrogen bonding N-H…N. These dimers are linked into infinite chains running along the c axis by hydrogen bonds C-H…O. The π-π-stacking interaction of aromatic rings is observed in all the compounds studied.     

Crystal structure of acrylamide

The crystal structure of acrylamide is re-determined by single crystal X-ray diffraction (133(1) K, BRUKER SMART 1000 CCD, a = 8.228(1) Å, b = 5.759(1) Å, c = 9.760(1) Å, β = 120.04(1)°, V = 400.3(1) Å,³, space group P2₁/c, Z = 4, R = 0.0543 for 867 reflections). In the structure strong hydrogen bonds N-H...O join the molecules of C₃H₅NO into bi-molecular layers that make C...C molecular contacts. It is demonstrated that the process of solid phase polymerization of acrylamide should proceed through the cleavage of double bonds C(1)=C(2) in the monomers and formation of bonds C(1)-C(1) and C(2)-C(2) between the closest carbon atoms of different layers.     

Crystal structures of 1,1,1-trifluoro-4-hydroxy-4-phenyl-but-3-en-2-one, 2,2,6,6-tetramethyl-3-hydroxy-hept-3-en-5-one, 2,2,6,6-tetramethyl-3-methylamino-hept-3-en-5-one and a study of the ability of these ligands to complex formation with metals

Crystal structures are determined (Bruker Nonius X8 Apex, 4K CCD-detector, λMoK _α, graphite monochromator, T 150 K and 293 K) for two β-diketones F₃CC(O)CH₂C(O)Ph (1) (space group P2₁/c, a = 7.0713(3)Å, b = 11.5190(6)Å, c = 11.3602(6) Å, β = 99.405(2)°, V = 912.90(8) ų, Z = 4), (CH₃)₃CC(O)CH₂C(O)C(CH₃)₃ (2) (space group Pbca, a = 11.5536(8) Å, b = 11.5796(10) Å, c = 17.2523(13) Å, V = 2308.1(3) ų, Z = 8) and a ketoimine (CH₃)₃CC(NCH₃)CH₂C(O)C(CH₃)₃ (3) (space group I4₁/a, a = 18.7687(6) Å, b = 18.7687(6) Å, c = 14.5182(6) Å, V = 5114.2(3) ų, Z = 16). All structures are molecular and comprise isolated molecules joined by van der Walls interactions. The substitution energy of a Na atom for a hydrogen atom in free ligands is calculated by the hybrid B3LYP quantum chemical method. A successful preparation of Na(I) chelates with ligands 1, 2 and failed attempts to prepare a complex with ligand 3 are in accordance with the calculations. Geometrical simulation of a copper(II) complex with ligand 3 reveals the overlap of CH₃ groups which hinders the complexation.     

Crystal structures of 6-[(2-hydroxy-1,1-bis-hydroxymethyl-ethylamino)-methylene]-4-nitro-cyclohexa-2,4-dienone hydrate and 6-[(2-hydroxy-1,1-bis-hydroxymethyl-ethylamino)-methylene]-4-bromo-cyclohexa-2,4-dienone

Crystal structures of 6-[(2-hydroxy-1,1-bis-hydroxymethyl-ethylamino)-methylene]-4-nitro-cyclohexa-2,4-dienone hydrate (I) and 6-[(2-hydroxy-1,1-bis-hydroxymethyl-ethylamino)-methylene]-4-bromo-cyclohexa-2,4-dienone (II) have been determined. The crystals of I are monoclinic, a = 16.957(1) Å, b = 10.729(2) Å, c = 7.240(3) Å; β = 99.56(3)°, space group P2₁/c, Z = 4, R = 0.0492. The crystals of II are triclinic, a = 10.282(2) Å, b = 7.189(3) Å, c = 16.831(3) Å; α = 90.67(3)°, β = 100.10(3)°, γ = 95.87(3)°; space group P-1, Z = 4, R = 0.0591. The independent part of the unit cell of I contains one unique molecule and water of crystallization, while in II — two unique molecules A and B. C(CH₂OH)₃ fragment of the molecule B manifests the disordering of alcohol oxygen atoms. Both in I and II, the salicylidene fragment of the molecules exists in the quinoid tautomeric form.     

Solid-state Structures for 2-Methoxy-1,3-xylyl-18-crown-5 and 2-Methoxy-1, 3-xylyl-21-crown-6: A Search for C–H···O Interactions

Solid-state structures have been determined for 2-methoxy-1,3-xylyl-18-crown-5 (4) (monoclinic, P2₁/n, a = 11.361(3) Å, b = 8.352(3) Å, c = 18.627(4) Å, β = 91.05(2)°, Z = 4) and 2-methoxy-1,3-xylyl-21-crown-6 (5) (monoclinic, Pc, a = 9.996(2) Å, b = 11.321(2) Å, c = 8.642(2) Å, β = 100.095(4)^o, Z = 2). In both molecules, the aromatic units are tilted with respect to the polyether ring and the methoxyl methyl hydrogens are oriented toward ether oxygen atoms of the rings. The interatomic distances, particularly the H···O distance and angles provide important information regarding the strength of the C–H···O interactions.     

Structure and some thermodynamic characteristics of the polymorphs of rubidium silicate Rb6Si10O23

The crystal structure of Rb₆Si₁₀O₂₃ at 296 and 773 K is determined using single-crystal X-ray diffraction. At room temperature the crystals are orthorhombic (space group Cm2m, a = 16.280(5) Å, b = 9.380(5) Å, c = 8.060(5) Å, Z = 2). At 698 K, a first-order phase transition occurs to a hexagonal phase (space group $P\bar 6$ , a = 9.475(5) Å, c = 8.200(5) Å, Z = 1). The silicon-oxygen tetrahedral frameworks of both polymorphs have the same topology: 12-membered channels running along axis c are connected through six-membered windows. The enthalpies of polymorphic transition and melting are determined to be 3.9 ± 0.3 and 160 ± 16 kJ/mol, respectively.     

Synthesis and structure of trans-diaquabis(dimethylsulfoxide)bis(3,5-dinitrobenzoato)copper(II)

Single crystal of [Cu(DMSO)₂(3,5-DNB)₂(OH₂)₂], where DMSO-dimethylsulfoxide, 3,5-DNB-3,5-dinitrobenzoate, has been synthesized and its crystal structure is determined. Crystals belong to monoclinic symmetry, space group is P2₁/n, Z = 2, a = 10.911(4) Å, b = 5.362(2) Å, c = 22.673(7) Å, β = 92.06(2)°, V = 1325.8(1) ų, T = 293 K. Final value of R = 0.040 was obtained for 1804 independent reflections with I > 3σ(I). The structure is built from complex molecules.     

Neutron powder diffraction and magnetic measurements on RbTil3, RbVI3, and CsVI3

CsVI₃ (a = 8.124(1) c = 6.774(1)Å,Z = 2, P6₃/mmc at 293 K) adopts the BaNiO₃ structure. Three-dimensional magnetic ordering takes place atT_c = 32(1)K. At 1.2 K the magnetic moment is 1.64(5) μ_B and it forms a 120° spin structure in the basal plane. RbVI₃ (a = 13.863(2) c = 6.807(1) Å,Z = 6, P6₃cmor P3¯c1 at 293 K) and RbTiI₃ (a = 14.024(3) Å,c = 6.796(2) Å,Z = 6, P6₃cm orP3¯c1 at 293 K) adopt a distorted BaNiO₃ structure, probably isostructural with KNiCl₃.T_c of RbVI₃ is 25(1) K. At 1.2 K, RbVI₃ has a spin structure similar to the one of CsVI₃ with a magnetic moment of 1.44(6) μ_B. RbTiI₃ shows no magnetic ordering at 4.2 K. It is shown that a deviation from the 120° structure is expected for compounds with a distorted BaNiO₃ structure such as RbVI₃. The cell dimensions of CsTiI₃ are reported.     

Crystal structure and thermal stability of A μ1,1-(OMe)-bridged dimeric Schiff base iron(III) complex

A new μ_1,1-OMe-bridged dimeric iron(III) complex, [Fe₂L₂(μ_1,1-OMe)₂(NCS)₂], where L is the deprotonated form of 2-[(2-ethylaminoethylimino)methyl]-5-methoxyphenol, has been prepared and structural characterized by elemental analysis, IR spectrum, and single crystal X-ray crystallography. The complex crystallizes in the monoclinic space group P2₁/c, with unit cell dimensions a = 10.156(1) Å, b = 11.972(1) Å, c = 14.256(2) Å, β = 102.643(3)°, V = 1691.3(3) ų, Z = 2, R ₁ = 0.0394, and wR ₂ = 0.0922. Each Fe atom in the complex is in an octahedral coordination. The Fe...Fe distance is 3.102(1) Å. The thermal stability of the complex was studied.     

Crystal structure of a complex of nickel(II) with 2-amino-4-imino-2-pentene

The structure of a nickel(II) complex with 2-amino-4-iminopentane is determined by X-ray crystallography at 150 K. Crystal data for C₁₀H₁₈N₄Ni are: a = 10.9802(3)Å, b = 13.5780(4)Å, c = 8.0935(2)Å, β = 107.304(1)°, space group P2₁/c, V = 1152.04(5) ų, Z = 4, d _x = 1.459 g/cm³, R = 0.0283. The structure is molecular; the metal atom is coordinated by four nitrogen atoms of two β-diimine ligands. The Ni-N distances in Ni(NacNac)₂ fall within 1.8571–1.8623 Å. The molecules in the crystal are joined by only van der Waals interactions.     

Crystal Chemistry Study of Two Magnesium Complexes with Trifluoroacetylacetone

Single crystal X-ray diffraction at a temperature of 150(2) K is used to determine the structures of two magnesium complexes with trifluoroacetylacetone: [Mg(tfac)₂]₃I and [Mg(H₂O)₂(tfac)₂]·H₂O II. Crystallographic data for I: space group P2₁/n, a = 12.5226(10) Å, b = 13.0591(7) Å, c = 12.6034(13) Å, β = 95.243(2)°, V = 2052.5(3) ų, Z = 2; for II: space group P2₁/c, a = 10.826(2) Å, b = 7.0742(13) Å, c = 21.858(4) Å, β = 102.712(5)°, V = 1632.9(5) ų, Z = 4. The isle structure of I is formed by linear trimeric molecules; in the structure of II the molecules of the complex and crystallization water form a layered framework using hydrogen bondings; the coordinated water molecules are in a trans position. The magnesium atoms have a distorted octahedral coordination environment, the Mg–O distances are 1.991(4)- 2.146(4) Å and 2.040(5)-2.073(5) Å in molecules of I and II respectively.     

Hydrogen bonding of catechol groups in the crystal structure of dihydrocaffeic acid

Dihydrocaffeic acid C₉H₁₀O₄ is a natural antioxidant. The crystal structure of dihydrocaffeic acid is determined; the crystallographic data at 100 K are: a = 11.3189(4) Å, b = 5.5824(1) Å, c = 13.8431(4) Å, β = 109.248(4)°, and V = 825.80(4) ų; the space group is P2₁/c, Z = 4. In addition to the formation of hydrogen bonds that are typical of acids, the compound has features that are important from the viewpoint of reactivity of dihydrocaffeic acid molecules. The position of one of the hydroxyl hydrogen atoms in the catechol group is disordered even at 100 K. The crystal structure of caffeic acid does not show such a disordering.     

Crystal structure of three solvates of 1,1′-binaphthyl-2,2′-bicarboxylic acid with 2-picoline

From solutions in 2-picoline (2-methylpyridine), depending on the temperature of crystallization, the universal clathratogen — 1,1′-binaphthyl-2,2′-bicarboxylic acid (BBA) — precipitates as crystals of three types with different composition and structure. Under normal conditions (room temperature), the precipitate is crystals of BBA disolvate with 2-picoline; a temperature reduction of 20°C results in the crystallization of monosolvate dihydrate; and a temperature increase of the same level results in the precipitation of monosolvate. That is, as the temperature of crystallization rises, the number of included guest molecules gradually decreases and the space where they are located becomes more closed. In 1:1:2 BBA/2-picoline/H₂O solvate (space group P2₁/n, a = 11.991(2) Å, b = 9.317(2) Å, c = 22.283(5) Å, β = 99.77(3)○, V = 2453.3(9) ų, Z = 4), the carboxyl groups of the BBA molecule at the C21 atom are deprotonated and the released proton goes to the nitrogen atom of 2-picoline. BBA molecules interact with those of 2-picoline and water via H bonds to form infinite chains in direction [111], which, in their turn, join together into infinite two-dimensional sheets parallel to plane (?101). 2-Picoline molecules are located in the channels. In BBA/2-picoline disolvate (space group C ₂/c, a = 11.7523(11) Å, b = 13.8563(13) Å, c = 17.9615(13) Å, β = 108.044(9)○, V = 2781.1(4) ų, Z = 4), one BBA molecule and two H bond 2-picoline molecules form a 0-dimensional associate of the type G-H-G. The solvent molecules are also located in the channels. In BBA/2-picoline monosolvate (space group P2₁/c, a = 9.299(5) Å, b = 12.727(5) Å, c = 19.011(5) Å, β = 95.248(5)○, V = 2240.5(16) ų, Z = 4), each BBA molecule is H-bonded with a 2-picoline molecule to form a 0-dimensional associate of the type H-G. Guest molecules are located in closed cavities.     

Crystal structures of cesium and rubidium chlorites

Rubidium and cesium chlorites are prepared and studied by single crystal and powder X-ray diffraction. The compounds are isostructural; crystallize in the orthorhombic system; space group Cmcm, Z = 4. Unit cell parameters: a = 6.3464(8) Å, b = 6.4223(8) Å, c = 7.7493(9) Å for RbClO₂ and a = 6.5998(9) Å, b = 6.6116(9) Å, c = 8.3161(11) Å for CsClO₂. The structures can be represented as 3D frameworks formed by metal cations and chlorite anions acting as tetradentate bridging and bidentate chelating oxygen ligands.