Conformational study on aryl ketones: The structure of 2,6-dimethyl-1,5-di-(2-methyl)-propanoylnaphthalene

C₂₀H₂₄O₂ (M _r =296.4) crystallizes in the monoclinic system, space groupC2/c witha=24.154(4),b=8.001(2),c=12.751(3) Å;=136.8(1)°;V=1686.9 ų,Z=4,D _c =1.17 g cm^–3,(Cu-)=5.4 cm^–1,=1.5418 Å,F(000)=640. The molecule in the solid state adopts a centrosymmetric geometry with the molecular center of symmetry coincident with a crystallographic center of symmetry. This fact forces the molecule to themeso conformation.     

The structure of a tetrabromotetrahydrodibenzocyclooctene

5, 6, 11, 12-Tetrabromo-5, 6, 11, 12-tetrahydrodibenzo[a, e]cyclooctene, C₁₆H₁₂Br₄, crystallizes in monoclinic space group P2₁/c witha=8.6917(7),b=15.135(2),c=12.892(2) Å, =101.836(8)°, V=1660.0(7) ų,Z=4. The structure was refined toR=0.058 for 3137 observed reflections. The molecule has approximate C₂ symmetry, with the eight-membered ring adopting the twist-boat conformation. The planes of the two phenyl rings form a dihedral angle of 117.3(2)°, C–Br distances range 1.965(5)–1.981(5) Å.     

Synthesis,nuclear magnetic resonance,and X-ray structural investigations of 1,6-diaza-9,12-dioxacyclotetradeca-2,5-dione

The molecular structure of l,6-diaza-9,12-dioxacyclotetradeca-2,5-dione has been investigated by X-ray and NMR methods. The crystals are monoclinic:C2/c,Z=4,a=8.5571(3),b=14.468(1),c=10.092(2) Å,=113.38(1)°. The structure was solved by direct methods, and refined toR=0.051 on 1082 unique reflections. The molecule exhibits a crystallographic twofold symmetry axis, the axis bisecting the 3C-4C and 10C-11C bonds, which is in full agreement with NMR findings.     

Crystal and molecular structure of (η5-C5H5)Ta(η2-C2H4)Cl2(PMe2Ph)2, a sterically crowded molecule which exhibits a distorted η5-coordination mode of the cyclopentadienyl ligand

The X-ray structure determination of (⁵-C₅H₅)Ta(²-C₂H₄)Cl₂(PMe₂Ph)₂ has revealed that the compound crystallizes in the orthorhombic space groupFdd2 witha=21.098(9),b=29.848(9),c=7.694(3) Å, andD _c=1.70g cm^–3 forZ=8. Least-squares refinement based on 893 independent observed reflections resulted in a finalR value of 0.026. The molecule resides on a crystallographic two-fold axis, with disordered ethylene and cyclopentadienyl groups. The Ta-Cl and Ta-P separations are 2.473(4) and 2.649(3) Å, respectively. Since the two carbon atoms of the ethylene molecule are indistinguishable from two of the cyclopentadienyl carbon atoms, the Ta-C bond lengths are 2.37(1) and 2.39(2) Å for the ethylene and for two of the cyclopentadienyl carbon atoms. The other three Ta-C(cyclopentadienyl) distances are much longer: 2.54(3), 2.54(3), and 2.62(3) Å. In order to achieve 18e ^– at the tantalum atom, the cyclopentadienyl ligand must be viewed in an ⁵-bonding mode. The variation of the Ta-C lengths is thus considered to be steric in origin. The carbon atoms of the C⁵H ₅ ^– group are planar to 0.03 Å.     

Crystal and molecular structure of the photocatalyst tris(2,2′-bipyrazine)ruthenium(II) hexafluorophosphate

The X-ray structure determination of the complex tris(2,2-bipyrazine)ruthenium(II) hexafluorophosphate, [Ru(C₈N₄H₆)₃](PF₆)₂, has shown that the compound crystallizes in the monoclinic space group P2₁/c witha=13.459(5),b=23.486(8),c=17.913(10) Å,=139.85(1)°, andZ=4. Each asymmetric unit also contains one dimethylformamide and one water molecule. Least-squares refinement led to an R factor of 0.074 based on 3463 reflections for which I>2(I). The [Ru(C₈N₄H₆)₃]²⁺ cation has no crystallographic symmetry, but the requirements for point symmetry 32 are nearly met. The six Ru-N bond lengths agree within experimental error and have an average length of 2.05(1) Å.     

Crystal and molecular structure of tetrakis-(phenylenethiourea)tellurium(II) perchlorate hexahydrate,C28H24N8O8S4Cl2Te·6H2O

The synthesis and structural characterization of the title compound, C₂₈H₂₄N₈O₈S₄Cl₂Te·6H₂O are reported. The crystals are triclinic, space group P¯1 (No. 2), withZ=1 in a unit cell of dimensionsa=10.312(7),b=7.144(6),c=14.256(7) Å,=83.04(5),=92.15(5), and=101.25(6)°,V _c =1022 ų. The structure was solved by Fourier methods, and refined by full-matrix least squares toR=0.073 andR _w =0.077 for 1305 unique reflections. The tellurium atom in the molecule lies at a crystallographic center of symmetry, and is bonded to four phenylenethiourea sulfur atoms in a near square-planar arrangement with Te-S(1)=2.666(5), Te-S(2)=2.675(6) Å, and S(1)-Te-S(2)=88.7(3)°. The ligands behave as thiones. The crystal packing is stabilized by the extensive hydrogen bonding involving oxygen and nitrogen atoms. The Cl-O bond lengths are 1.29-1.36 Å and the O-Cl-O angles are 90–130° in the ClO₄ ^– moiety, and differ considerably from the normal values of 1.44 Å and 109°, respectively.     

Structure of methylphenylhydrazone form of 2-(2-methylphenylazo)-1,3-indandione

The molecule crystallizes in a ketohydrazone tautomeric form. The tautomeric form is stabilized by a strong intramolecular hydrogen bond of 2.709(2) Å binding the 3-oxo to the nearest nitrogen atom in the azine chain. The compound crystallizes in the monoclinic space group P2_l/c witha=7.0470(4),b=11.3090(9),c=16.2250(4) Å, =90.310(3)°, V=1293.0(1) ų, Z=4,Dx=1.3576 g cm^–3 and (Cu-K)=7.03 cm^–1. The molecule is nearly planar not regarding the methyl group; the small deviations from planarity are indicative of intramolecular interactions between the phenylazo group and indandione group. Some of the bond lengths and angles found in the molecule are distorted due to resonance, -electron delocalization and strain. The relation between these chemical effects and structural results are discussed.     

Crystal and molecular structure of polymeric dilithium tetra(propionato)cadmium(II): A layered inorganic ionic-organic molecular structure

The structure of the title compound is made up of a central sheet containing only metal and oxygen atoms with organic moieties outside and between sheets. The Cd(II) is on a crystallographic center of symmetry and is bound to six propionate oxygen atoms to yield a coordination geometry of an approximate octahedron. Each lithium has four oxygen nearest neighbors to form a distorted tetrahedral geometry. The lithium atoms are in pairs via oxygen bridges to form unsymmetrical Li₂O₂ parallelograms with a crystallographic center of symmetry in the middle. Crystal data: Li₂Cd(C₃H₅O₂)₄,M _r =419, triclinic,P¯1,a=7.526(1),b=11.296(2),c=4.925(1) Å,=94.85(2),=98.04(2), =78.97(2)°,V=406(1) ų,Z=1,D _m =1.70(2),D _x =1.71 g cm^–3, T 298K,R=0.028 for 2303 reflections.     

bis-[2-(2-Methyl-3-butanone oxime)] hydrazine

C₁₀H₂₂N₄O₂, Mr=230.31, triclinic,P¯1,a=12.010(5),b=13.188(9),c=9.163(2)Å,=107.30(4),=108.35(3), =77.42(2)°,V=1303.(1)ų,Z=4,D _x=1.174(2) g cm^–3, (MoK)=0.71073 Å,=0.78 cm^–1,F(000)=504,T=297 K,R=0.039,R _w=0.054 for 3023 observed reflections (of 4521 unique data). The hard, transparent, colorless crystals give sharp, intense diffraction peaks; this may be related to the strong three dimensional hydrogen bonding involving the oxime groups as well as the hydrazine hydrogens. Bond distances and angles as well as torsion angles are in good agreement for the two independent molecules and are normal. Although there is near two-fold symmetry relating the two molecules, positions of neighboring groups removes a twofold crystallographic axis.     

Synthesis and structure of tris(N-methylaminoethanoldithiocarbamato)arsenic(III)

The title compound was synthesized by the interaction of arsenic(III)chloride with freshly prepared N-methylaminoethanoldithiocarbamic acid in methanol. The compound crystallized in the triclinic system, space groupP with two molecules per unit cell, the dimensions area=6.509(10)Å,b=14.077(3)Å,c=14.195(3)Å, =64.16(2)^o, =84.67(2)^o and =84.00(2)^o. The molecule is monomeric with three short (mean 2.320(3)Å) and three long (mean 2.927(2)Å) As-S bonds. Asymmetry in the As-S bonds is due to the presence of stereochemically active lone pair on arsenic and the coordination polyhedron deviates from the usual D₃ symmetry to C₃ symmetry. Disorder exists in one of the dithiocarbamate ligands probably due to the O...O interaction arising from the water molecule. The anisobidenticity of the As-S bond distances is as a consequence of stereochemical requirement of the ligand and the lone pair of electrons on arsenic.     

Single crystal X-ray structure of 11-acetoxy-4-deoxyasbestinin B

The crystal structure of 11-acetoxy-4-deoxyasbestinin B (C₂₂H₃₄O₄,M _r=362.49) crystallized in the orthorhombic space groupP2₁2₁2₁ witha=10.923(5)Å,b=11.127(5)Å,c=17.047(5)Å,V=2072(3)ų,Z=4,D _x=1.163g/cm^–3. MoK radiation was used for data collection at room temperature. The finalR=0.042 for 2464 observed reflections. The stereochemical assignments of the molecule from the 2-D NMR data are verified totally by the overall geometry of the molecule obtained from the X-ray diffraction analysis.     

Refinements of the crystal structures of 1,4-diphenylbutadiyne and its complex with two moles of Co2(CO)6

1,4-diphenylbutadiyne, C₁₆H₁₀, crystallizes in monoclinic space group P2₁/n witha=6.6152(6),b=6.0768(7),c=14.634(1) Å, =100.981(8)⁰,V=577.5(2) ų,Z=2. The structure was refined toR=0.077 andR _w=0.069 for 1007 observed reflections with CuK radiation. The molecule lies on an inversion center. Our determination represents and increase in precision of a factor of approximately three over the original determination. The 21 cobalt complex, C₁₆H₁₀[Co₂(CO)₆]₂, also crystallizes in monoclinic space group P2₁/n witha=8.9568(12),b=17.7057(10),c=18.5671(12) Å, =90.606(12)^o,V=2944.3(5) ų,Z=4. The structure was refined toR=0.032 andR _w=0.031 for 4312 observed reflections. The diphenylbutadiyne triple bonds elongate to 1.346(3) Å and the angles at the diyne C atoms decrease to 134.1(3)–144.9(3)^o upon complexation. The Co-Co distance is 2.4580(4)Å. Our data represent an increase in precision by a factor of 2–3 over the original determination.     

Crystal and molecular structure of a new biguanide metal complex, [Cu(AMNH)2]Cl2

The crystal structure of C₆H₁₆N₈O₂·CuCl₂, a biguanide metal complex, has been determined by X-ray diffraction data using MoK radiation. The compound crystallizes in the monoclinic space groupP2₁/a, witha=11.074(4),b=12.061(4),c=5.312(3)Å and=102.8(1)°.The structure was solved by direct methods and refined by full-matrix least-squares to a finalR value 0.037 with 1245 unique reflections. The complex molecule is centrosymmetric, with the Cu atom (0.5,0.5,0.5) on a crystallographic center of symmetry. The complex molecule is rhombic planar with a trans configuration.     

Studies of systemic acylanilide fungicides. Part I. Crystal structure and molecular conformation ofdl-methyl-N-(2,6-dimethylphenyl)-N-(2-methoxyacetyl) alaninate

The crystal structure of metalaxyl (C₁₅H₂₁NO₄) was determined by three-dimensional X-ray analysis from diffractometer data. The crystals are monoclinic,P2₁/c,a=7.851(3) Å,b=13.119(10) Å,c=15.107(7) Å,=101.71(6)°,Z=4,D _x=1.218 g cm^–3, (MoKa)=0.095 mm^–1. FinalR=0.079 for 1203 observed reflections. The dimethylphenyl ring is almost perpendicular to the amidic plane of the molecule.     

Synthesis,nuclear magnetic resonance,and X-ray investigations of 1,10-diazacyclooctadeca-2,9-dione

The structure of the title compound has been investigated in the solid state and in solution by X-ray and NMR methods, respectively. The crystals are triclinic, space groupP¯1, with cell dimensions:a=9.616(5),b=9.923(9),c=10.21(1)Å,=118.42(4)°,=96.10(5)°, =94.77(5)°. The structure was solved by direct methods, and refined against 3051 unique reflections by a full-matrix, least-squares procedure, givingR=0.049. A twofold symmetry element in the molecule, found from¹H-NMR investigations, has been established by X-ray investigations to be an approximate twofold symmetry axis, bisecting the C(5)-C(6) and C(14)-C(15) bonds.     

Crystal structures of the new diphosphates,K2NiP2O7 and K6Sr2Ni5(P2O7)5

Crystalline K₂NiP₂O₇ (I): monoclinic, P2₁,a=9.230(2),b=17.540(8),c=8.319(9)Å, =91.44(2)°,Z=8,d _calc=3.067 g cm^–3, MoK =0.71069Å,R/R _w=6.5/9.4%, is characterized by the existence of face sharing NiO₆ octahedra with Ni–Ni separation of 2.827 Å (Ni–O; 1.93(2)–2.17(2)Å). K⁺ is seen in sites of seven, six, and fivefold coordination (K–O, averages; 2.83(2), 2.81(2), and 2.77(2)Å, respectively) P₂O₇ ^4– groups are observed in semieclipsed conformation. K₆Sr₂Ni₅(P₂O₇)₅ (II) crystallizes in monoclinic space group P2₁/c;a=11.038(7),b=9.533(13),c=7.438(2)Å, =100.13(4)°,D _calc=3.309 g cm^–3,Z=2,R/R _w=6.4/8.1%. Nickel atoms are distributed on planes parallel to the crystallographic (100) plane at =0 and =0.5. On the planes, =0, Ni²⁺ ions form successive linked trimers of edge sharing NiO₆ octahedra (Ni–Ni, 3.018(1), 3.008(1)Å; Ni–O, av 2.07(2)Å). The intermediate planes (=0.5) contain isolated and six coordinate Ni²⁺ ions (Ni–O av. 2.09(2)Å). Seven-coordinate potassium ions (K–O, av. 2.74(2)Å) are located on intermediate planes at =0.25 and 0.75. P₂O₇ ^4– groups are found in eclipsed conformation. Strontium atoms are located between nickel and potassium planes and are surrounded by seven oxygen atoms (Sr–O, av. 2.586(2)Å).     

Crystal structure of hexakis(tetrahydrofuran)sodium hexacarbonylvanadate(−I), [Na(THF)6 +][V(CO)6 −]

The title compound crystallizes in the space group with unit cell parameters (hexagonal setting)a=14.922(5)Å,c=14.379(9)Å,V=2773(3)ų andZ=3. The cation and the anion each lie on a site of (S₆) symmetry. Interatomic distances include Na–O(THF)=2.40(1) Å and V–C(CO)=1.91(2) Å.     

Crystal structure of Co4(CO)10S2 and Co4(CO)10Se2; v(CO) vibrations of a model cluster molecule: Co4(CO)10S2

The crystal structure of Co₄(CO)₁₀S₂ has been redetermined and that of Co₄(CO)₁₀Se₂ obtained by X-ray analysis. The compounds are monoclinic and isomorphous, space groupP2₁/n,Z=2, with (S compound)a=10.42(2)Å,b=6.794(1)Å,c=12.421(2)Å,=97.27(1) and (Se compound)a=10.110(2)Å,b=6.747(2)Å,c=12.592(4)Å,=96.37(2); finalR(S)=0.029,R _w =0.032 for 1414 reflections and finalR (Se)=0.052,R _w =0.054 for 1264 reflections. The molecules, which lie on a crystallographic center of symmetry, consist of a rectangle with Co atoms at the corners, each face of the rectangle being capped by a chalcogen atom. Each Co atom is bonded to two terminal CO groups; there are two bridging CO groups, one on each member of a pair of opposite sides of the rectangle. The vibrational spectra of the sulfur compound are considered in detail. A study of the crystal structure, and recognition of an approximate spectroscopic space group, are shown to be essential for an understanding of thev(CO) infrared spectrum of polycrystalline Co₄(CO)₁₀S₂. In this molecule, intramolecular vibrational coupling in the crystal leads to extensive modifications of the infrared-activev(CO) molecular coordinates.     

Reaction of trimethylaluminum with crown ethers. IV. Crystal structure of (18-crown-6)tetrakis-(trimethylaluminum)·p-xylene solvate

The title compound was prepared by the addition of A1Me₃ to a suspension of 18-crown-6 inp-xylene. The large, colorless, air-sensitive crystals belong to the monoclinic space group P2₁/n witha=14.822(6),b=7.894(4),c=18.805(6) Å,=105.40(4)°, andD _calc=1.03 g cm^–3 forZ=2. The finalR value based on 1758 observed reflections is 0.043. The molecule lies on a crystallographic inversion center and exhibits four strong Al-O bonds. The two independent Al-O distances are 1.978(3) and 2.000(3) Å. The oxygen atoms deviate from the mean plane of the crown, alternating above and below, by 0.13, 0.15, and 0.20 Å, respectively. Thep-xylene molecule is also positioned about a center of inversion.     

Crystal and molecular structure of trans-(tricarbonyl)bis(trans-2,2,3,4,4-pentamethyl-1-phenylphosphetane)iron

The title compound crystallizes in the monoclinic space groupP2₁/a witha=13.092(2) Å,b=15.853(2) Å,c=15.406(3) Å,=103.00(1)°,V=3116(1) ų, andD _calc=1.237 g cm^–3 forZ=4. The structure was solved by direct methods, and refined to a finalR value of 0.057. The phosphetane ligands adopt a nonlinear trans relationship. The four-membered rings are non-planar and have different flap angles of 6.1 and 20.3°. Virtual coupling is evident in the¹³C NMR spectrum of the title compound. Comparison of the¹³C NMR spectral data of this molecule with the parent phosphine ligand, the ligand oxide, and the mono-phosphine iron complex is provided.