Structure analysis of 3β-chloro-6-nitrocholest-5-ene

The crystal structure of the title compound (C₂₇H₄₄NO₂Cl) is determined by X-ray structure analysis. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ with the unit cell parameters a = 7.207(1) Å, b = 11.292(1) Å, and c = 32.373(5) Å. The structure is solved by direct methods and refined to R = 0.060. Rings A and C exist in the chair conformation. Ring B adopts a half-chair conformation, and ring D is a 13β envelope. The A/B ring junction is quasi-trans, while the B/C and C/D ring systems are trans fused about the C(8)–C(9) and C(13)–C(14) bonds, respectively. Molecules are linked together by the C-H?O hydrogen bonds.     

Crystal and molecular structure of 12(S)-acetoxy-4(S),8(R)-dimethyl-3-oxo-1(R)-5(S)-9(S)-2-oxatricyclo[4.4.7.01,9.3.4.8.01,5]tridecane

The structure of the title compound, a cyclic ether acetate lactone, has been established uniquely by X-ray crystallography. C₁₆H₂₄O₄ is orthorhombic, space groupP2₁2₁2₁, with the cell dimensionsa=7.524(2),b=10.686(2),c=19.472(2) Å,V=1565.6(4) ų,Z=4,M _r=280.4,D _x=1.19 g cm^–3,D _o=1.20 g cm^–3,F(000)=608,T=293 K, finalR=0.050. The two cyclohexane ring junction iscis while the lactone ring junction istrans. Both the cyclohexane rings have the chair conformation and the -lactone ring has an envelope conformation with C(7) being at the tip of the flap. The acetoxy side chain is-equatorial. There is an intramolecular C-H---O interaction C(4)O(4)=2.666(4) Å.N. C. L. Communication No. 5064.     

Crystal structure of guggulsterone Z

The crystal structure of the title compound (4,17(20)-trans-pregnadiene-3,16-dione, C₂₁H₂₈O₂) has been determined by direct methods using single-crystal X-ray diffraction data. The compound crystallizes into the orthorhombic space group P2₁2₁2₁ with the unit cell parameters a = 7.908(2) Å, b = 13.611(3) Å, c = 16.309(4) Å, and Z = 4. The structure has been refined to R = 0.058 for 3667 observed reflections. The bond distances and angles are in good agreement with guggulsterone E and other related steroid molecules. Ring A exists in the distorted sofa conformation, while rings B and C adopt the distorted chair conformation. Five-membered ring D is intermediate between the half-chair and envelope conformations. The A/B ring junction is quasi-trans, while ring systems B/C and C/D are trans fused about the C(8)–C(9) and C(13)–C(14) bonds, respectively. The steroid nucleus has a small twist, as shown by the C(19)–C(10)...C(13)–C(18) pseudo-torsion angle of 7.2°. The crystal structure is stabilized by intra-and intermolecular C-H...O hydrogen bonds.     

Stereochemical studies of oligomers. IV: structure of bis-3,3,5-trimethylcyclohexyl phthalate

C₂₆H₃₈O₄,Mr=414.6, is monoclinic,P2₁/c, witha=15.059(2),b=7.348(2),c=23.164(3) Å,β=90.35(16)°,V _c =2563.13(85) ų,D _x =1.07(4) g cm^?3,μ(CuKα)=5.28 cm^?1. The structure was determined by direct methods and refined by full-matrix least squares toR=0.074 for 2479 observed reflections. The two cyclohexane rings both adopt a chair conformation.     

Conformational analysis of 13-hydroxy-α-isolupanine epimers

13α-Hydroxy-α-isolupanine (I) and 13β-hydroxy-α-isolupanine (II) crystallize in the space groupP2₁2₁2₁ witha=13.123(2),b=13.221(3),c=8.224(1) Å,Z=4 anda=9.745(2),b=11.383(1),c=12.710(2) Å,Z=4, respectively. Structural differences between the epimeric molecules are concentrated around ringA. In (I) ringA has a half-chair conformation, and in (II) it is a distorted sofa. TheA/B ring junction configuration isquasi-trans in the case of (I) andquasi-cis in (II). The above differences can be explained by the different intermolecular interactions observed in these two structures.     

Crystal structure of cholest-4-ene-3,6-dione: A steroid

The crystal structure of cholest-4-ene-3,6-dione (C₂₇H₄₄O₂) has been determined by X-ray diffraction methods. The compound crystallizes in the monoclinic crystal system (space group P2₁) with the unit cell parameters a = 10.503(4) Å, b = 8.059(1) Å, c = 14.649(1) Å, β = 105.4(2)°, and Z = 2. The structure has been refined to an R value of 0.035 for 2252 observed reflections. Ring A of the steroid nucleus exists in a sofa conformation, while rings B and C adopt a chair conformation. The five-membered ring D exhibits a half-chair conformation. The molecules in the unit cell are linked together by the C-H?O hydrogen bonds.     

Intra- vs intermolecular hydrogen bonding. The crystal structure of 5-methyl-2-hydroxyacetophenone thiosemicarbazone monohydrate and salicylaldehyde-2-methylthiosemicarbazone monohydrate

The crystal structure of 5-methyl-acetophenonethiosemicarbazone monohydrate,A, and salicylaldehyde-2-methylthiosemicarbazone monohydrate,B, were determined using single crystal X-ray diffraction.A crystallizes in the monoclinic space groupC2/c, with lattice parametersa=14.161(2),b=15.753(1) Å,c=11.084(1) Å, β=112.59(1)° andZ=4, yielding a calculated density ofD _calc=1.352 mg/m³.B crystallizes in the triclinic space groupP1, witha=7.233(2) Å,b=7.371(2) Å,c=11.841(2) Å, α=82.77(2)°, β=78.33(2)°, γ=63.06(2)° andD _calc=1.371 mg/m³ forZ=2,. In bothA andB the immine nitrogen and the sulfur atom areanti with respect to N2-C8. WhileA presents the usual intramolecular six membered hydrogen bond ring,B has instead an intermolecular hydrogen bond between the hydroxy moiety of the salicyladehyde and a water molecule. AM1 calculations agree with the experimental conformations observed in both compounds.     

Crystal structure of diheterolevulosan II: α-d-Fructofuranose-β-d-fructopyranose 1,2′:2,1′ dianhydride and molecular mechanics calculations on diheterolevulosan II and IV with chair and boat conformations of the central 1,4-dioxane ring

C₁₂H₂₀O₁₀,M _r=324.28, orthorhombic,P2₁2₁2₁,a=9.4476(8),b=10.2247(8),c=13.5827(11) Å,V=1312.07(18) ų,Z=4,D _x=1.642 g cm^?3, MoKα radiation (λ=0.71073 Å)μ=1.4 cm^?1,F(000)=688,T=295 K, finalR=0.041 for 1089 reflections withI≥2.5σa(I). The molecule consists of aβ-d-fructopyranose and a α-d-fructofuranose ring which are linked by a 1,4-dioxane ring. The pyranose ring and the dioxane ring both have a chair conformation, and the furanose ring has an envelope conformation. All six hydroxyl groups act as donors in intermolecular hydrogen bonding. Each molecule is hydrogen-bonded to eight neighbor molecules by fourteen hydrogen bonds, forming a three-dimensional framework. The hydrogen bonds of varying geometry give rise to five sharp hydroxyl stretch vibrations in the infrared spectrum. In diheterolevulosan IV the central dioxane ring is a boat. Molecular mechanics calculations on diheterolevulosan II and IV having different boat and chair conformations of the dioxane ring show that the lowest energy conformations correspond to the conformations observed in the crystal structure. For comparison the calculations also have been applied to 1,4-dioxane having boat and chair conformations.     

X-ray structure analysis of 3β-hydroxy-4-(1,4-oxazin-4-yl)-androstane (C31H54NO2)

The crystal structure of 3β-hydroxy-4-(1,4-oxazin-4-yl)-androstane (C₃₁H₅₄NO₂) has been determined by X-ray crystallographic techniques. The compound crystallizes in the orthorhombic space group P2₁2₁2 with the following unit-cell parameters: a = 7.124(1) Å, b = 10.127(1) Å, c = 40.660(1) Å, V = 2933.4(1) ų, and Z = 4. The structure has been solved by direct methods and refined to an R factor of 0.067. Three six-membered rings, A, C, and E, exist in the chair conformation, while the ring B adopts a distorted half-chair conformation. The five-membered ring, D, has a distorted envelope conformation. The crystal structure is stabilized by strong intermolecular O-H...O hydrogen bonds.     

1,3,5-trichlorotricyanobenzene complexes with mesitylene (1/1) and benzene (1/3)

Trichlorotricyanobenzene-mesitylene (1/1) is monoclinic, space group P2₁/n; at ?88°Ca=10.509(3),b=14.863(7),c=11.518(3) Å, β=99.38(2)⁰,V=1775(2) ų,D _x =1.409(2) g cm^?3,Z=4. Trichlorotricyanobenzene-benzene (1/3) is hexagonal, space group $P\bar 6$ ; at ?99°Ca=17.3914(3),c=7.2673(1) Å,V=1903.6(1) ų,D _x =1.2844(1) g cm^?3,Z=3. In both complexes there are stacks of alternating trichlorotricyanobenzene and hydrocarbon molecules. In both complexes there are sheets of molecules perpendicular to the stacks. In the mesitylene complex these sheets contain equal numbers of both kinds of molecules with the trichlorotricyanobenzene molecules arranged in tapes. In the benzene complex the sheets contain only one kind of molecule or the other. The sheets containing the trichlorotricyanobenzene molecules have approximately linear C?N...Cl?C intermolecular interactions with N...Cl distances about 3.02 å.     

Crystallographic analysis of Royline monohydrate [C25H41NO7 · H2O]

The crystal and molecular structures of the alkaloid Royline {(1α,6β,14α, 16β)-20-ethyl-4-hydroxymethyl)-1,6,14,16-tetramethoxyaconitane-7,8-diol} with a water molecule has been determined by X-ray diffraction analysis. The compound crystallizes in the space group P2₁ with the unit cell parameters a = 10.985(1) Å, b = 7.898(1) Å, c = 14.956(1) Å, β = 102.96(1)°, V = 1264.52 ų, Z = 2, λMoK _α = 0.71073 Å, and R = 0.033 for 2067 observed reflections. Rings A, B, and C adopt a chair conformation, ring D is a half-boat, ring E is a half-chair, and ring F is in an envelope conformation with C(14) at the flap. Molecules are linked together in the crystal by hydrogen bonds.     

The molecular structures of two furanoheliangolides

The heliangolide-class sesquiterpene lactone 8β-angeloyloxy-9α-acetoxycalyculatolide, C₂₂H₂₆O₈,1, crystallizes in orthorhombic space groupP2₁2₁2₁ witha=12.455(3),b=12.601(3),c=14.023(5) Å,V=2200(1)Å,³ Z=4.R=0.059 for 1735 observed data. The 11,13-dihydro-11α, 13-epoxyatripliciolide-8β-angelate, C₂₀H₂₂O₇. 1/2 H₂O,2, crystallizes as the hemihydrate with two molecules in the asymmetric unit in triclinic space groupP1 witha=9.422(1),b=9.559(1),c=12.358(3) Å, α=101.62(2)°, β=91.30(2)°, γ=117.80(1)°,V=955.6(7)ų,Z=2.R=0.046 for 3607 observed data. In both, the 10-membered rings adopt approximate chair-boat conformations. Their conformations are typical for heliangolides. The methyl group C14 is α, while the C-15 has a β-orientation. The α-methylene-γ-lactone istrans-fused at C6 and C7 with H6 β and H7 α. In compound2, the epoxide at C11–C13 has an α orientation.     

Structure of (N-(2-hydroxyphenyl)-salicylaldiminopiperidino) Ni(II) complex

The crystal and molecular structure of the title complex, C₁₈H₁₉N₂O₂Ni, has been determined by direct methods. The compound crystallizes in the monoclinic crystal system witha=22.973(1),b=5.212(1),c=27.076(1)Å, β=106.46(1)°, space groupC2/c,V=3109.1(6)ų, Z=8, andD _x=1.51g cm^?3. The nickel atom is in a slightly distorted square-planar environment of two oxygens [Ni(1)?O(1) 1.824(3) and Ni(1)?O(2) 1.856(3)Å] and two nitrogens [Ni(1)?N(1) 1.849(3) and Ni(1)?N(2) 1.932(3)Å] with O?Ni?N angles between 85.7(1) and 97.1(1)°. The nickel atom is 0.006 Å out of the plane of its ligands.     

Crystal structure of 5α-cholest-6-one

The crystal and molecular structure of the steroid 5α-cholest-6-one has been determined by X-ray diffraction analysis. The compound crystallizes in space group P2₁ with the unit cell parameters a = 10.575(1) Å, b = 7.698(1) Å, c = 15.284(2) Å, β= 99.34(1)°, V = 1227.72 ų, Z = 2, and R = 0.054 for 1634 observed reflections. The six-membered rings (A, B, and C) have the chair conformations, whereas the five-membered ring Dis intermediate between 13β-envelope and 13β-14α half-chair. All the rings of the steroid skeleton are trans connected. The molecules are linked together by the intermolecular C-H?O hydrogen bonds.     

The structure of 2R-(3′S-benzyloxy-5′S-hydroxy-2′R-hydroxymethyl-1′-oxacyclohexan-6′S-yl)-propionic acid-1,5′-lactone,C16H20O5

The title compound is C₁₆H₂₀O₅, MW=292.3, orthorhombic,P2₁2₁2₁,a=9.741(2),b=29.391(7),c=5.354(1) Å from diffractometer measurements,V=1532.8 ų,Z=4,D _c =1.267 g cm^?3,D _o =1.271 g cm^?3 (ether/1,1,2,2-tetrabromoethane), λ(Mo Kα)=0.71069 Å,F(000)=624,μ=1.02 cm^?1, crystal dimensions 0.23×0.23×0.40 mm,R=0.049 for 1164 observed reflections. The molecule contains a possibly significant asymmetric ether linkage between the oxacyclohexane ring and the highly anisotropic benzyl ring. The packing consists of zigzagged chains parallel to thea-axis formed by hydrogen bonds. The chains are separated by van der Waals contacts.     

N,N-Dimethylglycine hydrochloride

Crystals of C₄H₁₀NO₂Cl, M _r =139.58 are monoclinic,P2₁/c, witha=7.061(2),b=7.194(2),c=13.932(3) Å,β=98.88(2)°,V=699.2(5) ų,Z=4,D _x=1.326(1) g cm^?3. The structure was solved by hand application of direct methods and refined to a goodness of fit of 1.7 for 1212 reflections and 114 parameters (R=0.028 for 1202 reflections withF ²>0).     

The molecular structures of three germacrolides related to parthenolide

The germacrolide-class sesquiterpene lactone, 1,10-epoxyparthenolide, C₁₅H₂₀O₄,1, crystallizes with two independent molecules in monoclinic space groupP2₁ witha=10.6845(5),b=9.0763(4),c=15.4326(7) Å, β=105.887(4)°,V=1439.4(3) ų,Z=4.R=0.037 for 2425 observed data. Its 11βH, 13-dihydro-derivative 1,10-epoxydihydroparthenolide, C₁₅H₂₂O₄,2, crystallizes in orthorhombic space groupP2₁2₁2₁ witha=7.6414(10),b=12.559(2),c=14.6821(14) Å,V=1409.0(3) ų Z=4.R=0.031 for 1555 observed data. The corresponding unexposidized compound, 11βH,13-dihydrocostunolide, C₁₅H₂₂O₂,3, crystallizes with three independent molecules in orthorhombic space groupP2₁2₁2₁ witha=7.3576(5),b=23.505(3),c=24.185(2) Å,V=4182(1) ų,Z=12.R=0.070 for 2767 observed data. In all, the 10-membered rings adopt approximate chair-chair conformations. In all, the double bonds or epoxidized double bonds are E, both methyl groups on the 10-ring are β, and the α-methylene-γ-lactone (or α-methyl-γ-lactone) istrans-fused at C6 and C7 with H6 β and H7 α. In the dihydro compounds, the H at C11 is β.     

X-ray crystallography of cholest-3,5-diene-7-one

The molecular structure of cholest-3,5-diene-7-one (C₂₇H₄₂O) is determined by X-ray diffraction. The compound crystallizes in the orthorhombic crystal system (space group P2₁2₁2₁) with unit cell parameters a = 11.281(5) Å, b = 11.350(5) Å, c= 18.518(5) Å, and Z = 4. The structure is solved by direct methods and refined to an R-value of 0.054 for 1070 observed reflections [F_o > 4σ(F_o)]. Ring A adopts a distorted half-chair conformation, ring B exists in sofa conformation, ring C acquires a chair conformation, and the five-membered ring D occurs in distorted half-chair conformation. The crystal structure is stabilized by van der Waals forces.     

Molecular and crystal structure of bis-quinolizidine immonium salts,II: Δ1(6)-dehydrosparteinium monoperchlorate

₁₍₆₎-Dehydrosparteinium monoperchlorate, [C₁₅H₂₅N₂]⁺·ClO ₄ ^– , is orthorhombicP2₁2₁2₁,a=12.473(2),b=24.292(3),c=10.835(1) Å,V _c =3353.7(9) ų,Z=8,D _x =1.32,D _m =1.32 g cm^–3, (CuK)=20.7 cm^–1. The finalR was 0.097 for 2091 observed counter reflections. A partial disorder of the crystal structure has been observed. The two independent perchlorate anions are orientationally disordered, and the peripheral atoms in the cation skeletons have large temperature factors due both to conformational disorder of ringsA and to disordered orientations of the whole cations alike. In ringsA, atoms C(3) and C(4), trans-annular to the immonium bond, are disordered to a different extent in each of the two independent cations. RingsB,C, andD have sofa (distorted towards half-chair), chair, and chair conformations, respectively. The quinolizidinium and quinolizidine moieties have planar and cis configurations, respectively. The title compound was obtained from ⁵-dehydrosparteine, the product of mercuric acetate dehydrogenation of sparteine at room temperature. From¹³C NMR measurements in²H₂O and in DMSO-²H₆ it is evident that, in solution, the molecular geometry with chair/chair cis-ring fusion within the quinolizidine moiety is present, as was found in the crystalline state by X-ray analysis.     

Fluoro-containing complexes of chromium (III). II. Crystal structure oftrans-difluorodiaquo-ethylenediaminechromium(III) chloride

The results of an X-ray structure determination of one of the three possible chloride salts of [Cr(en) F₂(OH₂)₂]⁺ show the two fluoro ligands to betrans to each other. The purple crystals are monoclinic in the space groupC2/c-C _2h ⁶ , witha=11.409(3),b=9.319(2),c=10.260(3) Å,β=128.73(2)° andD _c =1.73 g cm^?3 forZ=4. Least-squares refinement based on 1341 independent observed reflections resulted in a finalR of 0.026. The molecule lies on a crystallographic two-fold axis, and the Cr-F, Cr-N, and Cr-O bond lengths are 1.885(1), 2.044(2), and 1.997(2) Å respectively. It is suggested that the ill-defined shoulder in the visible electronic spectrum of this complex is indicative of atrans dihalo geometry.