Structure of bis(2-pyridine-N-oxide) diselenide and its formation from tetraphenylantimony(V)selenopyridine-N-oxide

The structure of bis(2-pyridine-N-oxide) diselenide was determined by single crystal X-ray diffraction. The compound crystallized in the triclinic system and the structure was solved in the space group . The lattice constants were determined to bea=7.174(2),b=7.176(2),c=11.070(2) , =87.67(2)°, =73.68(2)°, and =89.57(2)°;Z=2,D _x=1.906 Mg m^–3. The final least squares refinement based on 1942 independent observed reflections yieldedR=0.033,wR=0.044. The Se–Se bond length is 2.326(1) and each Se is coordinated to the O atom of the corresponding N-oxide moiety at a distance of about 2.6 .     

Crystal structures of 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanedione and 1-(1,3-benzodioxol-5-yl)-3-(2,4-dimethoxyphenyl)-1,3-propanedione

1-(2-Hydroxyphenyl)-3-phenyl-1,3-propanedione crystallizes in the triclinic space group (a=5.4233(5),b=13.910(1),c=17.036(1) Å, =68.311(6), =80.854(7), =78.760(8)°) as two independent enolic tautomers in which the hydroxyl and phenolic protons are hydrogen bonded to the ketonic oxygen atom. The structure was refined toR=0.039 for 2085I3(I) reflections. 1-(1,3-Benzodioxol-5-yl)-3-(2,4-dimethoxyphenyl)-1,3-propanedione, which belongs to the triclinic space group (a=7.3990(7),b=8.1239(5),c=14.004(1) Å, =86.673(6). =88.574(7), =64.885(7)°) also exists in the enolic form. The structure was refined toR=0.040 for 1564I3(I) reflections.     

Crystal and molecular structure of 1,N6-ethenoadenosine hydrochloride

The X-ray structure of 1,N ⁶-ethenoadenosine hydrochloride, C₁₂H₁₄N₅O₄Cl, has been determined from three-dimensional diffractometer data and refined by full-matrix least-squares techniques. The crystals are monoclinic:P2₁ No. 14,a=6.1540(5),b=18.511(1),c=6.7412(4) Å,=112.602(5)°,andZ=2; finalR=0.045 for 2662 observed reflections. The crystal and molecular structure of Ado·HC1 is very similar to that of Ado·HC1. On the other hand, the dimensions and conformation of the Ado·H⁺ cation are drastically different from those of Et Ado·H⁺. The adenosine·H⁺ moiety is not planar but has an S shape. The ribose is 2-endo-3-exo puckered, with ag ⁺ side chain; the glycosidic torsion angle is in theanti region. The structure contains a three-dimensional network of H bonds in which also C-HA interactions seem to play an important role. There is no base stacking in the structure.     

Crystal structure of 1,2,4,6-tetraphenylpyridinium tetrabromoferrate(III)

The title structure, which belongs to the triclinicP¯1 space group witha=13.901(4),b=10.732(1),c=10.570(8)Å=109.14(4),=96.17(4), =90.34(2)°, is refined toR=0.052 for 2985I3(I) reflections. The structure consists of a non-interacting 1,2,4,6-tetraphenylpyridinium and tetrahedral tetrabromoferrate (III) ions.     

Crystal and molecular structure of nitrito-bis(1,3-propanediamine) nickel(II) tetraphenylborate

The title compound is orthorhombic,M _r =590.2,P2₁2₁2₁ (No. 19),a=9.865(2),b=9.924(2),c=31.202(7) Å,V=3055(2) ų,Z=4,D _x =1.283 g cm^–3, (MoK );F(000)=1256; (MoK )=6.76 cm^–1, finalR=0.052 for 1441 reflections I2.5(I). The nitrite group is chelated via the two oxygen atoms; the two six-membered rings resulting from the coordination of the 1,3-propanediamine ligands to the nickel(II) atom are in the chair conformation. The Ni-N and Ni-O distances average 2.07(1) and 2.14(2) Å respectively. The two Ni-O distances are nearly equivalent.     

The crystal structure of 2-nitroresorcinol

2-Nitroresorcinol is triclinic, space group P; at –100°Ca=7.083(2),b=7.696(2),c=6.607(2) Å, =74.61(2), =77.81(2), =68.64(2)°,V=320.8(2) ų,D _x=1.606(1) g cm^–3,Z=2. The two hydroxyl groups form symmetric intramolecular hydrogen bonds to the nitro group. The molecules pack in stacks held together by - interaction with adjacent molecules in a head-to-tail arrangement.     

Synthesis and structural characterization of 2,6-bis-(N-methylenemorpholino)-4-ter-butylphenol

The crystal and molecular structure of the title compound, C₂₀H₃₂N₂O₃, has been determined from X-ray diffraction data using CuK radiation (=1.5418 Å). The compound crystallizes in triclinic space groupP1^¯ with a=8.828(1),b=18.680(1),c=6.272(2)Å, =93.42(1), =0.24(2), =77.93(1)°,V=1009.4(2)ų, andZ=2. The structure was solved by direct methods and the full-matrix least-squares refinement leads the finalR-factor to 0.065 for 3481 observed reflections withI3(I). The phenyl ring is planar and the morpholino rings assume perfect chair conformation. The molecules are held together by van der Waals forces.DCB Contribution No. 810.     

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.     

Crystal structure of tylophorine methiodide monohydrate,C25H30NO 4 + I−·H2O

The crystal structure of tylophorine (Chemical name 2,3,6,7 tetramethoxy phenanthro [9,10:6, 7] indolizidine. Contribution No. 0871.) methiodide monohydrate has been determined. C₂₅H₃₀NO ₄ ⁺ I^–·H₂0, triclinic, P,a=8.831(1)Å, b=10.842(2),c=13.902(2), =105.0(1)^o, =104.7(1), =97.3(1),V=1210.22ų, Z=2,D _x =1.428 g./cm^–3, (CuK)=1.54184Å, (CUK)=107.2 cm^–1, F(000)=544,T=295^oK,R=0.038,Rw=0.046, for 2331 observed reflections withI2(I). Apart from van der Waals forces, the structure is stabilized by two hydrogen bonds of the type Ow(H) ... O and Ow(H) ... I^– involving the water molecule as the donor and atom O4 of the methoxy group and I^– as acceptors.     

Schiff bases and their complexes with metal ions. Part II. Structures of N-n-butyl-2-hydroxy-1-naphthaldimine and bis[N-n-pentyl-2-hydroxy-1-naphthaldiminato]nickel(II)

The Schiff base ligand (1), [C₁₅H₁₇NO] crystallizes in the monoclinic space group P2₁/c witha=10.054(3),b=10.313(3), c=13.173(4)Å, =107.42(4)°,V=1303.2(7)ų,Z=4,Dx=1.159 g cm^–3, and (MoK)=0.674 cm^–1. The C2-O[1.23(1)Å] and C3–C4 [1.33(2)Å] bond lengths are short, due to its quinoidal structure. In the Schiff base nickel complex (2), [Ni(C₁₆H₁₈NO)₂] the asymmetric unit is comprised of two half-complexes. It crystallizes in the triclinic space group witha=5.124(3),b=16.227(3),c=16.886(4)Å, =95.47(8), =96.00(1), =90.71(4)°,V=1389.6(9) ų,Z=2,Dx=1.289 g cm^–3, and (MoK) =12.1 cm^–1. The coordination of the Ni(II) ions are square planar with bond angles between 87.9(1) and 92.1(1)°. The Ni–O and Ni–N distances are 1.819(2), 1.922(2) and 1.823(2), 1.914(3)Å in these two complexes.     

Crystal structures of twoN-substituted 2-thioxo-1,3-dithiole-4-carboxamides

The two closely related compoundsN,N-dimethyl 5-(methylthio)-2-thioxo-1,3-dithiole-4-carboxamide1 andN-(p-methoxy-phenyl)-N-methyl 5-(methylthio)-2-thioxo-1,3-dithiole-4-carboxamide2 have been characterized by X-ray crystal structure determination. Crystal data for1: triclinic, ,a=6.767(1),b=12.594(2),c=6.648(1) Å, =101.38(1), =93.37(2), =79.62(1)°,V=546.2 ų,Z=2. Crystal data for2: monoclinic, Cc,a=19.836(4),b=6.057(1),c=15.860(3) Å, =127.61(3)°,V=1509.5ų,Z=4. The molecular structures of1 and2 show remarkable differences concerning the conformational behavior. These differences are related to the nature of the substituents at the nitrogen atom. The presence of an aromatic system in2 leads to an almost planar arrangement of the -oxoketene dithioacetal moiety. This effect is accompanied by a short intramolecular S...O contact of 2.648(2) Å. In the absence of an aromatic system, as is the case for compound1, neither a resonance effect along the -oxoketene dithioacetal fragment nor a short S...O distance is observed.     

Crystal structures of five policyclic compounds related to the natural product forskolin

(3(Z),4,6a,9a,9b)-(±)-3a,4,6a,7,8,9,9a,9b-octahydro-4,7,7, 9b-tetramethyl-3a-[3-(methoxymethyloxy)-3-methyl-1-butenyl]-5H-naphto[1,8-de]-1,3-dioxin-6-one (I), C₂₂H₃₆O₅,M _r=378.51, monoclinic,P2₁/n,a=6.330(1),b=14.576(2),c=22.837(2)Å,=93.04(1)°,V=2104.1(2)ų,Z=4,D _c=1.19 Mg/m³, (MoK)=0.71069Å,=0.8 cm^–1,F(000)=832,T=298 K,R=0.054 for 1971 observed reflections; (7a,10a,10b,12)-(±)-7a,9, 10,10a,10b,11,12,12a-octahydro-2,2,10,10,10b,12a-hexamethyl-2H,8H-1-benzopyrano[4a,5,6,-de][1,3,2]-benzodioxin-11-one (II), C₂₀H₂₉O₄,M _r=334.5, triclinic,P-1,a=10.595(2),b=12.152(1),c=8.073(1)Å,=106.53(1),=105.65(1), =66.29(1)°,V=897.9(2)ų,Z=2,D _c=1.24 Mg/m³, (MoK)=0.71069Å,=0.8 cm^–1,F(000)=362,T=298 K,R=0.046 for 2848 observed reflections; (7a,10a,10b,12, 12a)-(±)-7a,9,10,10a,10b,11,12,12a-octahydro-2,2,10,10,10b,12a-hexamethyl-2H,8H-1-benzopyrano[4a,5,6-de][1,3,2]-benzodioxin-11, 12-diol (III), C₂₀H₃₂O₅ (two molecules in the asymmetric unit),M _r=352.2, triclinic,P-1,a=12.948(3),b=13.615(3),c=12.197(4)Å,=101.16(2),=111.88(2), =69.48(2)°,V=1863.8(9)ų,Z=2,D _C=1.26 Mg/m³,(MoK)=0.71069 Å,=0.8 cm^–1,F(000)=768,T=298 K,R=0.060 for 4570 observed reflections; 4-acetoxy-4-[[(4a,5,8a)-(±)-hexahydro-4a,6,6-trimethyl-4H-1,3-benzodioxin-4-one]-5-yl]butan-2-one (IV), C₁₇H₂₆O₆,M _r=326.4, monoclinic,P2₁/c,a=10.495(2),b=12.050(2),c=14.216(2)Å,=108.51(1)°,V=1704.8(5)ų,Z=4,D _c=1.27 Mg/m³,(MoK)=0.71069 Å,=0.9 cm^–1,F(000)=704,T=298 K,R=0.049 for2455 observed reflections; (3a,4,5,6,6a,9a,9b)-(±)-4,5-epoxy-decahydro-3, 3a-dihydroxy-2-ethoxy-4,7,7,9b-tetramethyl-naphto-[1,8-bc]-pyran-6-ol-acetate (V), C₂₀H₃₂O₇,M _r=383.5, monoclinic,C2/c,a=10.353(2),b=17.975(3),c=21.188(3)Å,=91.29(1)°,V=3942(1)ų,Z=8,D _c=1.29 Mg/m³,(MoK)=0.71069 Å,=0.8 cm^–1,F(000)=1664,T=298 K,R=0.051 for 2120 observed reflections. We report here the complete structures of four decalin derivatives (compoundsI, II, III, V) and one related compound (compoundIV) synthetized in order to find an efficient synthetic approach for the natural productforskolin.     

Crystal and molecular structure of glutaconic acid

Crystals of Glutaconic acid, C₅O₄H₆, are triclinic, space group P , with the cell dimensions (294 K), a = 4.843(1) Å, b = 10.188(1) Å, c = 12.609(1) Å, = 83.46(1)°, = 80.02(1)°, = 78.71(1)°, V = 598.8(3) ų with D _m = 1.47, D _x = 1.443 gcm ^–3. There are two independent molecules in the asymmetric unit. The crystal structure was solved by multi solution techniques with three-dimensional data collected (to the limit of 2_max of 154° for Cu K) on a CAD-4 diffractometer. The crystal structure was refined by full matrix least squares method to a final R value of 0.058 for 1894 reflections (I 2). The two independent molecules are conformationally similar. In both the molecules, the carboxyl ends are trans to each other with respect to the central C=C double bond in the structure. The molecules are self-paired through dimeric type of hydrogen bonding involving the terminal carboxyl groups, characteristic of many dicarboxylic acid structures. The crystal structure is stabilized by a series of O–HO hydrogen bonds of the glutaconic acid dimeric units. Free radicals have been shown to be involved in a number of chemical and biological processes and lipid peroxidation is one such process. Glutaconic acid was chosen as a simple unsaturated model of a fatty acid. When irradiated with X-rays, it was found to form a stable free radical structure. ESR (electron spin resonance) and ENDOR (electron nuclear double resonance) studies were used to characterize the free radical structure and correlate with the X-ray structure. The free radical was found to be HOOC–CH=CH–CH–COOH with the glutaconic acid in the trans conformation. The damage occurs at the -carbon atom (the first carbon of the double bond). The damage consists of a loss of an hydrogen atom. This results in an unpaired electron in the p-orbital delocalized over the three central carbon atoms. The two -proton couplings were resolved in the ENDOR spectrum. ESR spectra show that the two molecules are magnetically similar that is in agreement with the crystal structure that reveals that the two independent molecules are conformationally similar. This is the characteristic type of damage that occurs in lipids when they form free radicals that in turn reacts with oxygen and other compounds and ultimately results in cellular damage.     

Crystal structure of lanthanum(III) oxalate decahydrate

La₂(C₂O₄)₃·10H₂O crystallizes in space groupP2¹/c (No. 14) witha=11.382(6),b=9.624(5),c=10.502(8) Å,=114.52(4)°, andZ=2. The structure (R=0.029 for 3190 MoK data) is composed of two-dimensional networks of edge-sharing 153 coordination polyhedra matching the (020) set of planes, each La(III) atom being surrounded by three ⁴ chelating oxalate groups and three aqua ligands with La-O distances in the range 2.518(4)–2.622(4) Å. The remaining water molecules are disordered over seven principal sites in the intervening space.     

Hydrogen-bonded networks formed by substituted 2,6-diarylpyrazines

The X-ray crystal structure of 2,6-bis(4-hydroxyphenyl)pyrazine and 2,6-bis(4carboxyphenyl)pyrazine are reported. The structure of the 2,6-bis(4-carboxyphenyl) pyrazine dimethylsulfoxide complex (C₁₈H₁₂N₂O₄)(C₂H₆OS) is triclinic, P-1, with a = 7.9933(8), b = 10.7165(10), c = 12.1337(12) Å, = 66.385(2), = 84.070(2), = 77.219(2). The structure comprises stacked two-dimensional sheets of the hydrogen bonded complex. The two-dimensional sheets comprise hydrogen-bonded ribbons of the (carboxyphenyl)pyrazine that are connected by bridging hydrogen bonds to the dimethylsulfoxide. The structure of 2,6-bis(4-hydroxyphenyl)pyrazine, C₁₆H₁₂N₂O₂, is monoclinic, P2₁/c, with a = 10.6107(13) Å, b = 14.6743(18) Å, c = 8.3772(10) Å and = 104.982(2). The structure reveals that two-dimensional hydrogen-bonded sheets are formed with pyrazine–phenol and phenol–phenol hydrogen bonds.     

Structural investigation on hexasubstituted benzene derivatives. Part 2: The structure of metadinitrotetramethylbenzene and molecular mechanics analysis on meta and ortho derivatives

C₁₀H₁₂N₂O₄ (M r=224.2) crystallizes in the monoclinic system, space groupP2₁/mwitha=15.462(4),b=7.926(3),c=8.972(3) Å;=90.2(1)°;V=1099.5(6) ų;Z=4;D _c=1.35 gcm^–3;(Cu-K)=8.6 cm^–1; =1.5418 Å;F(000)=472. The position of the molecule on a crystallographic mirror plane forces the NO₂ plane to be normal to the benzene ring. The-electron-withdrawing character of the NO₂ groups induces a deformation on the geometry of the benzene.     

Synthesis and structural characterization of the bitopic ferrocene-based tris(pyrazolyl)methane ligand Fe[C5H4CH2OCH2C(pz)3]2 (pz = pyrazolyl ring)

The structure of Fe[C₅H₄CH₂OCH₂C(pz)₃]₂ (pz = pyrazolyl ring) contains 1.5 independent molecules in the asymmetric unit. One molecule has no imposed symmetry with the iron atom located on a general position while in the other the iron atom is located on an inversion center. The two independent molecules are arranged into a three-dimensional supramolecular structure by a series of C—H s N and C—H s O weak hydrogen bonding interactions and C—H s interactions. The crystals are triclinic, space group, P , with a = 8.1202(4) Å, b = 16.7209(9) Å, c = 18.6540(10) Å = 85.8270(10), = 85.4740(10), = 81.5910(10), and Z = 3     

X-ray crystal structure oftrans-dichlorobis(2,6-lutidine)palladium(II)

The X-ray structure oftrans-(2,6-lutidine)₂PdCl₂ has been determined. Golden orange crystals of the complex crystallize in the triclinic space group , with cell dimensionsa=7.6950(8),b=7.9705(10),c=8.0485(8)Å, =116.967(9), =113.343(8), and =93.836(9)°;V=385.18(7)ų andZ=2. 1336 unique reflections withI _net>3 (I) on refinement afforded values ofR=0.018 andR _w=0.023.     

Isomerism in parabutylchloral; x-ray crystallographic determinations of 2,4,6-tris(1′,1′,2′-trichloropropyl)-1,3,5-trioxanes

-Parabutylchloral (2,4,6-tris(1,1,2-trichloropropyl)-1,3,5-trioxane, C₁₂H₁₅Cl₉O₃) crystallizes in the orthorhombic space groupP2₁2₁2₁ (No. 19) witha=12.165(6),b=9.964(5),c=17.433(9) Å,Z=4. The finalR value is 0.043 for 1667 observed reflections.-Parabutylchloral crystallizes in the orthorhombic space groupPna2₁ (No. 33), witha=12.387(6),b=10.488(5),c=16.605(8) Å,Z=4. The finalR value is 0.047 for 1417 observed reflections.Unlike the geometric isomers- and-parachloral (CCl₃CHO)₃ which exist in boat andcis,cis-chair conformations, the- and-forms of parabutylchloral (CH₃CHClCCl₂CHO)₃ are now shown by X-ray crystallography not to be geometric isomers. Both forms exist incis,cis-chair conformations and the isomerism arises from the chirality of the side chains at the-carbon atoms. In the-form only two of the side chains have the same chirality, but in the-form the chirality at all the-carbon atoms is the same. The X-ray results are supplemented by¹H and¹³C nuclear magnetic resonance spectroscopy and by mass spectrometry.We thank the CSIR (Pretoria) for collecting the diffractometer data, the CSIR and the University of Cape Town for research grants, Dr. M. L. Niven for crystallographic assistance, and Miss C. Angus for preparing parabutylchloral and separating the isomers. The 500 MHz NMR data are courtesy of Mr. Ivan Antonowitz of the CSIR.     

Crystal and molecular structures of three modifications of the androgen dehydroepiandrosterone (DHEA)

The crystal and molecular structures of three forms of the androgen DHEA (dehydroepiandrosterone) have been determined by single crystal X-ray diffraction. They are: Form I, a polymorph crystallizing in space group P2₁ withZ=4; Form S1, a hydrate with composition DHEA. (1/4)H₂O, space group C2,Z=8; and Form S4, a methanol half-solvate, DHEA. (1/2)CH₃OH, space group C222₁,Z=8. The A, B, and C steroid ring conformations adopted in the five crystallographically independent DHEA molecules are invariably: chair, 8, 9-half-chair, and chair, respectively, while the D ring conformation ranges from a 14-envelope to a 13, 14-half-chair. In Forms I and S1, intermolecular hydrogen bonding is of the head-to-tail type with water molecules participating as donors in Form S1. In Form S4, DHEA molecules pack in head-to-head fashion, their hydroxyl groups being linked by hydrogen bonding to the solvent hydroxyl group. The hydroxyl H atoms of both DHEA and the included methanol are disordered, giving rise to an unusual linearly-propagating flip-flop hydrogen bonding scheme.