Crystal and molecular structure of ibogamine: An alkaloid fromStemmadenia galeottiana

C₁₉H₂₄N₂ is orthorhombic,D ₂ ⁴ -P2₁2₁2₁. Unit cell dimensions at 293 K area=10.346(7),b=10.464(3),c=29.083(10)Å,V=3149(4) ų,D _c =1.18 g cm^–3, andZ=8. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 1968 reflections down toR=0.045 and R=0.047. The structural features determined from chemical and spectroscopic studies are confirmed and extended. There are two crystallographically independent molecules (A and B). In both A and B molecules the indole ring system is planar and attached to a seven-membered nitrogen-containing ring with a distorted-chair conformation. The indole and seven-membered rings lie close to the same plane [dihedral angles are 6.6(5) and 4.1(5)° for the A and B molecules, respectively], while the C(5)-N(6)-C(19)-C(2) atoms of the central axis of theiso-quinuclidine tricyclic structure are almost perpendicular to seven-membered ring [dihedral angles are 84.7(5) and 87.9(5)° for the A and B molecules, respectively]. The A and B molecules in the crystal are packed at normal van der Waals distances.     

Crystal and molecular structure of isovoacangine: An alkaloid from Stemmadenia Donnell-Smithii

C₂₂H₂₈N₂O₃ is monoclinic,P2₁. Unit-cell dimensions at 293 K area=10.023(5),b=6.615(3),c=14.749(6) Å,=91.41(4)°,V=978(1) ų,D _c =1.25 g cm^–3, andZ=2. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 1421 reflections toR=0.057. The structural features determined from chemical and spectroscopic studies are confirmed and extended. The stereochemistry at C(4) and C(18) is 4S and 18S. The indole ring is not planar and the seven-membered nitrogen-containing ring adopts a distorted-chair conformation. The angle between the normals to the planes of the indole and sevenmembered rings is 15.2(1)°, while the C(5)-N(6)-C(19)-C(2) atoms of the central axis of the iso-quinuclidine tricyclic structure is 69.1(1)°. The molecules in the crystal are held together by a hydrogen bond, a C-HO contact, and van der Waals interactions.     

Structural and spectral studies of N-trans-cinnamylidene-m-toluidine and N-trans-cinnamylidene-m-chloroaniline

N-trans-cinnamylidene-m-toluidine (1) C₁₆H₁₅N, and N-trans-cinnamylidene-m-chloroaniline (2) C₁₅H₁₂NCl form isomorphous crystals which are monoclinic, space group P2_l/c, with unit cell dimensionsa=5.967(2),b=13.793(3),c=15.048(5) Å, =91.97(3)° anda=5.868(2),b=13.788(4),c=15.191(4) Å, =91.87(3)°, respectively. The single-crystal X-ray structure determinations of the title compounds revealtrans structures. Ring (A) C_10–15 and ring (B) C_1–6, are practically planar in both structures with dihedral angels of 61.3(3) and 63.6(2)°, respectively.¹H nmr, u.v. and i.r. spectra are also reported.     

Crystal and molecular structure of 2,3,6,7-tetramethoxy-9-trichloromethyl-10-carboxymethyl-9,10-dihydroanthracene

Cl₃O₆C₂₁H₂₁,M _r =475.75, orthorhombic,P2₁2₁2₁,a=21.895(3),b=12.101(2), andc=8.237(2) Å,V=2182.4(7) ų,D _x =1.45 g cm^–3 forZ=4, (MoK)=0.71069 Å=3.99 cm^–1,F(000) 984, room temperature,R=0.035 for 1877 observed reflections. The molecule exhibits a folded conformation: the dihedral angle between the benzene rings is 28.3(1)°. The central ring is characterized by acis diaxal configuration of hydrogen atoms in the 9, 10 positions, confirming the 13-C NMR results.     

Crystal structure of DMAP-C-HMTCAQ,C30H20N6O2, N,N-dimethylaminophenyl-carbamate-2′-hydroxymethyl-11,11,12,12-tetracyano-anthraquinodimethan

C₃₀H₂₀N₆O₂,M _r =496.53, triclinic, P¯1,a=8.748(4) Å,b=10.989(3) Å,c=13.541(8) Å,=90.67(4)°,=99.15(4)°, =98.62(4)°,V=1269.8 ų,Z=2,D _c =1.30 g cm^–3, (Mo K)=0.71069 Å,=1.02 cm^–1,F(000)=516.0,T=295(3) K,R=0.127% for 1839 observed reflections, 363 parameters. The molecule has an extended, rather than a folded geometry. The HMTCAQ moiety has mm symmetry, and is shaped like a hawk about to land. The anthraquinone ring system is folded, with a dihedral angle of 37.3°; the two propanedinitrile groups have a mutual dihedral angle of 80.2°. The dihedral angle between the central ring of the TCAQ moiety and the phenyl ring is 37.2°. The phenyl rings stack over each other with a perpendicular distance of 3.36 Å. The dipole moment of the molecule is 6.254 Debyes; the crystal Madelung energy isE _M=–8.989 kJ/mol; the dispersion energy isE _d =–318.370 kJ/mol; the repulsion energy isE _r =130.139 kJ/mol.On leave at Department of Chemistry, University of Alabama, Tuscaloosa, Ala. 35487-9671.     

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.     

Structure and conformation of 6,8-dinitro-2,4-bis(trichloromethyl)-1,3-benzdioxin: X-ray crystallographic determination

6,8-dinitro-2,4-bis(trichloromethyl)-1,3-benzdioxin is monoclinic,P2₁/c,Z=4,a=12.348(2),b=11.575(3),c=12.183(4) Å,=107.48(2)°. The structure was solved by direct methods, from data collected at room temperature on an Enraf-Nonius CAD4 diffractometer, and refined by least-squares to a finalR value of 0.032 using 2192 reflections. The heterocyclic ring is an envelope structure, the dihedral angle between the plane of the aromatic ring and that containing five of the atoms of the heterocycle being 4.98(6)°. One -CCl₃ group is pseudoequatorial while the (Ar-C)CCl₃ group is pseudoaxial. C-C_eq 1.526(3) Å; C-C_ax 1.537(3) Å; C-C(C_ax)-O 112.4(2)°; C(C_ax)-O-C(C_eq) 115.2(2)°.     

X-ray structural and spectroscopic investigation of 1-piperidine-2,4-dinitrobenzene

The crystal structure of the title compound (C₁₁H₁₃N₃O₄) has been determined by single-crystal X-ray diffraction. The compound is monoclinic, space group P2₁/n, witha=9.968(2),b=9.156(2),c=13.249(2)Å, =102.05(2)°, andD _x=1.563 gcm^–3 forZ=4. The aromatic ring shows a slight boat deformation. Theo- andp-NO₂ groups are twisted out of the plane of the phenyl ring by 39.0(2)° and 4.4(1)°, respectively. The piperidine ring exhibits a slightly deformed chair conformation. Short C–H...O intermolecular contacts stabilize the three dimensional structure. UV and NMR data indicate that the molecule in solution presents a conformation similar to that of the the solid state.     

Crystal and molecular structure of 2,2-diphenyl-5-dichloromethylene-3-oxazoline-4-ethylcarboxylate

The structure of an oxazoline compound: 2,2-diphenyl-5-dichloromethylene-3-oxazoline-4-ethylcarboxylate has been established uniquely by X-ray crystallography. C₁₉H₁₅Cl₂NO₃ is monoclinic, space groupP2₁/n, with the cell dimensionsa=8.170(1),b=23.559(2),c=9.962(1) Å,=105.53(1)°,V=1847.5(3) ų,Z=4,M _r=376.2,D _x=1.35,D _o=1.36 g cm^–3,F(000)=776,T=293 K,=33.2 cm^–1, finalR=0.062 for 2321 observed reflections. Two phenyl rings make a dihedral angle of 83.3(4)° and are equally inclined to oxazoline ring plane. The ethylcarboxylate group is planar and is at an angle of 76.1(4)° with respect to oxazoline ring plane.N.C.L. Communication No. 5360.     

Studies of systemic acylanilide fungicides. Part IV. Crystal structure and molecular conformation ofN-(2-methoxyacetyl)-N-(2,6-xylyl)-α-amino-γ-butyrolactone

The crystal structure of the title compound (C₁₅H₁₉NO₄, MW 277.3 amu) was determined by three-dimensional X-ray analysis from diffractometer data. Crystal data are: monoclinic,P2₁/n,a=9.600(3) Å,b=11.964(6) Å,c=12.802(4) Å,=101.25(3)°,V=1442.1(16) ų,Z=4;D _x =1.277 Mg m^–3;(MoK)=0.10 mm^–1. FinalR=0.055 for 1686 observed reflections having 2 (MoK)<50° andI>2.5 (I). The compound is isostructural withN-(2-methoxyacetyl)-N-(2,6-xylyl)-3-amino-1,3-oxazolidin-2-one. The dimethylphenyl ring is almost perpendicular to the amidic plane of the molecule (dihedral angle 81.9°); the butyrolactone ring is in the typical envelope conformation.     

Crystal structure and absolute configuration of the indole alkaloid arborescidine C

The structure and absolute configuration (3R, 17R) of the indole alkaloid arborescidine C were determined by x-ray diffraction. The six-membered ring assumes a half-chair conformation and the seven-membered ring has a twist-like conformation. The crystal packing is characterized by intermolecular hydrogen-bonding between the hydroxyl group and nitrogen atom N4 which leads to the formation of infinite chains of molecules along the a-axis of the crystal. The absolute configurations of two related indole alkaloids, arborescidine B and arborescidine D are inferred from the experimentally determined configuration of arborescidin C molecule. A comparison of the present structure with that of a related indole alkaloid akagerine showed significant conformational and configurational differences. Crystal data: C₁₆H₁₉N₂OBr, orthorhombic, P2₁2₁2, a = 10.3376(8), b = 15.461(4), c = 9.2094(9)Å, V = 1471.9(6)ų, Z = 4, D _calc = 1.510 g cm^–3, = 1.54178Å.     

Structure of 1-ethyl-2-(2′-chloro-4′-nitrostyryl)benzimidazole

The title compound C₁₇H₁₄ClN₃O₂ (et-4-nsbiz) is monoclinic, witha=12.240(2),b=12.144(4),c=10.544(4)Å,=100.09(2)°,V=1543(1)ų,Z=4,D _x =1.411 g cm^–3, (MoK)=0.71073Å,=2.57 cm^–1,F(000)=680,M _r =327.77,T=298K. The structure was solved by heavy atom and Fourier methods and refined toR=0.049 for 1503 unique observed reflections in space groupP2₁/c. Except for the ethyl group, the molecule is almost planar, with a dihedral angle of 9.5(5)° between the benzimidazole and phenyl rings. The dihedral angle between the ethyl group and the benzimidazole ring to which it is attached is 91.5(2)°.     

A twist boat: Structure and conformation oftrans-2,4,6-tris(trichloromethyl)-1,3,5-trithian

Trans-2,4,6-tris(trichloromethyl)-1,3,5-trithian, (CCl₃·CHS)₃, has been prepared free from persistent impurification bycis-trans-2,4,6-tris(trichloromethyl)-1,3,5-oxadithian and its conformation determined by single crystal x-ray crystallography. The title compound is orthorhombic,Pbca, a=10.479(10),b=27.957(14),c=11.093(3) Å,V=3250 ų,Z=8. The structure was solved by direct methods, from data collected at room temperature on an Enraf-Nonius CAD4 diffractometer, and refined by full-matrix least squares to a finalR value at 0.074 using 1186 reflections. The molecule exhibits a twist boat conformation with the –CCl₃ groups occupying pseudoequatorial positions. The torsion angles in the trithian ring are successively 29(1), –79(1), 41(1), 41(1), –84(1), 39(1)°. Average values are: S-C 1.82(2), C(ring)-C(Cl₃) 1.56(4), C-Cl 1.76(2) Å, S-C-S 112.7(2)°. The C-S-C angles are 97.4(7), 101.4(7), 97.3(7)°.     

Structure of 2-(2′-bromo-5′-nitrostyryl)benzothiazole

The title compound C₁₅H₉BrN₂O₂S (brnsb) is monoclinic, witha=7.730(2),b=26.847(5),c=7.773(2) Å,=117.48(1)°,V=1431(1) ų,Z=4,D _x=1.677,(MoK)=29.9 cm^–1,F(000)=720,T=298K in space groupP2₁/c. The structure was solved by heavy atom and Fourier methods and refined toR=0.034 for 1776 unique observed reflections. The molecule is nearly planar, with a dihedral angle of only 3.8(1.1)° between the benzothiazole and phenyl rings. The C-S-C angle in the thiazole ring is 89.0°, while the C-N-C angle in that ring is 111.5(3)°.     

Complexation with diol host compounds. Part 3. Molecular inclusion of 4-methylcyclohexanone and 2-methylcyclohexanone by the host,trans-9,10-dihydroxy-9,10-diphenyl-9,10-dihydroanthracene

The structures of the 12 molecular complexes oftrans-9,10-dihydroxy-9,10-diphenyl-9,10-dihydroanthracene with 4-methylcyclohexanone (1) and with 2-methylcyclohexanone (2) have been determined by X-ray crystallography. The crystal data are as follows: Compound (1):P2₂/c,a=8.838(2) Å,b=8.92(1) Å,c=20.879(8)=Å,=98.67(2)°,V=1627(2) ų,Z=2 andR=0.062 for 2201 unique MoK reflections; Compound (2):P¯1,a=8.917(3) Å,b=9.900(2) Å,c=11.250(4) Å,a=68.72(2)°,=64.39(3)°, =74.86(2)°,V=828.1(5) ų,Z=1 andR=0.098 for 2563 unique reflections. Both inclusion compounds exhibit O-HO=C hydrogen bonding interactions. The thermal properties of these compounds have been characterized by DTA and TGA thermograms.     

Crystal structure of orellanine hydrate

Orellanine hydrate crystallizes in the monoclinic space groupC2/c with unit cell parametersa=11.516(1) Å,b=8.573(1) Å,c=11.167(2) Å,=110.92(1)°. The finalR andR _w equal 0.041 and 0.046, respectively. The water molecule in the hydrate binds bothN-oxide oxygens of the orellanine molecule by hydrogen bonds, thus fixing the conformation. The hydrate so formed occupies a special position on a twofold axis which passes through the midpoint of the C2-C2 bond distance and the OW atom. Both of the hydroxy-groups participate also in intermolecular hydrogen bonds. As a consequence of the rigid hydrogen bonded network, the dihedral angle between these two pyridil rings of the orellanine molecule is equal to 90.20(5)°.     

Molecular structure of the 3-oxide of N-benzyl-3,6-dithiacyclohexene-1,2-dicarboximide

Crystals of the title compound (C₁₃H₁₁,NO₃S₂) are orthorhombic: space groupPbca,a=23.030(3),b=12.897(2),c=8.695(1). The structure was solved by direct methods and refined by full-matrix least-squares procedures to giveR=0.073 andR _w =0.071 for 1303 intensities above 3(I). The 3,6-dithiacyclohexene ring has a deformed half-chair conformation with the axial configuration of the S(3)=O bond. Oxidation of the S(3) atom brings about different lengths of analogous intraring bonds [S(3)-C(2)=1.756(7) and S(6)-C(1)=1.710(7) Å] and angles [C(4)-S(3)-C(2)=95.5(3)° and C(1)-S(6)-C(5)=98.7(3)°]. The structure contains a shortened SO intermolecular contact of 3.053(5) Å.     

Solid state conformational parameters in dibenzo[b,f]heteroepin drugs: Crystal structures of 3-methoxy-10-methyl-11-phenyldibenzo[b,f]thiepine and 3-allyloxy-10-ethyl-11-phenyldibenzo[b,f]oxepine

The structures of 3-methoxy-10-methyl-11-phenyldibenzo[b, f]thiepine (I) [C₂₂H₁₈OS, tetragonal,I4₁/a, witha=33.81(1),c=6.065(5)Å,Z=16] and 3-allyloxy-10-ethyl-11-phenyldibenzo[b,f]oxepine (II) [C₂₅H₂₂O₂, mono-clinic,P2₁/c,a=12.115(7),b=16.316(9),c=10.136(7)Å,=105.05(9)°,Z=4] have been determined by the symbolic addition procedure and refined by least-squares method to anR of 0.090 for 784 diffractometer-measured reflections (I) and to anR of 0.083 for 442 reflections (II). The dihedral angle between the phenyl-ring mean planes is 111.3° in (I) and 121.1° in (II), the middle seven-membered ring has the boat conformation, and the tricyclic moiety has twist and skew values of 6° and 0.42 Å in (I) and 0.3° and 0.79 Å in (II). The overall conformational characteristic for the tricyclic (6, 7, 6)-dibenzo[b,f]heteroepin derivatives have been reviewed to gain a better understanding of what requirements may be important for interaction of drugs of this class at the receptor site.     

Studies of substituted quinoxaline-di-N-oxides. Part 1. Crystal structure and molecular conformation of 2-[N-(2-hydroxyethyl)carboxamide]-3-methylquinoxaline 1,4-dioxide

A single crystal X-ray investigation of the yellow 2-[N-(2-hydroxyethyl) carboxamide]-3-methylquinoxaline 1,4-dioxide, a commercially available growth promoter used in agricultural stock farming, shows that the molecule is planar. The dihedral angle between the benzene and heterocyclic rings is 0.5°. The N(1)-O(1) and N(2)-O(2) distances are: 1.286(1) and 1.304(1) Å. The C(1)-C(2) bond of the pyrazine ring is not lengthened by substitution at the C(1) and C(2) atoms and is 1.421(2) Å. The atoms O(1) and O(2) deviate by 0.036(2) and 0.123(2) Å from the least-squares plane through the heterocyclic ring. The deviation of the C(12) atom is –0.012(2) Å. The plane through the atoms C(1), C(9), N(3), and O(3) makes an angle of 100.5(2)° with the heterocyclic ring plane. Intermolecular hydrogen bonds O(4)-HO(4)O(3) between the hydroxyl and carbonyl groups generated alternating, antiparalled chains extending in thea direction. The crystals are triclinic,P¯1 (No. 2), witha=7.469(2),b=8.111(2),c=10.357(3) Å,=80.11(2),=88.90(2), =67.73(2)°, andV=571.3(2) ų. The structure was solved by direct phase determination guided by negative quartets and refined by full-matrix least squares to anR value of 0.041 for 2159 observed reflections.Commercially known asOlaquindox.     

Crystal and molecular structure of inner-chelatetrans-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diacetatozinc(II), C16H28N2O8Zn

The molecular structure of trans-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diacetatozinc(II), complex (I), has been investigated by X-ray diffraction methods. It crystallizes in the monoclinic space groupP2₁/c, witha=16.229(2),b=12.001(1),c=9.778(1) Å,=95.59(1)°, andZ=4. The structure was solved by direct methods, and refined by full-matrix least-squares toR=0.048. The zinc cation, placed asymmetrically in the macro-ring cavity, is six-coordinated to 2 N- and 2 O-atoms of the macrocycle, and to 2 O-atoms of two acetate groups, thus forming an irregular octahedral coordination sphere. The 18-diaza-crown-6 ring reveals approximate twofold symmetry (s=0.1 Å), with the axis through C2-C3 and C11-C12 midpoints.