Crystal structure and conformation of N-(t-butoxycarbonyl)-L-isoleucyl-L-alanine benzylester

C₂₂N₂O₅H₃₂,M _r =404.5, monoclinic,C2,a=21.781(5),b=5.065(1),c=22.333(4)Å,=112.81(2)°,V=2271.1(9)ų,D _calc=1.148 g cm³, (CuK )=1.5418 Å,=5.89 cm^–1,F(000)=848, room temperature,R=0.058 for 2178 unique reflections [I2.5(I)]. The peptide linkage is in thetrans conformation. The molecule adopts the-sheet structure. The crystal structure is stabilized by a three-dimensional network of N-HO and C-HO hydrogen bonds.DCB Contribution No. 813.     

Crystal and molecular structure of cesium isothiocyanatotrimethylaluminate,Cs[Al(CH3)3NCS]

The crystal structure of the title compound has been determined from three-dimensional X-ray diffraction data, and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupP2₁/c, witha = 8.849(4),b = 13.798(5),c = 7.943(4) Å, = 102.98(3) °, andD _x = 1.85g cm^–3 forZ = 4. The finalR factor for 1283 observed reflections is 0.046. The aluminum atom is bonded to the nitrogen atom of the thiocyanate ligand, where the Al-N bond length is 1.94(1) Å. The SCN is linear, and the CN-Al angle is 175(1) °. The cesium ion exhibits four contacts less than 3.60 Å: Cs C(thiocyanate) = 3.39(1) Å, Cs C(methyl) = 3.52(1) Å, Cs C.(methyl) = 3.56(1) Å, and Cs N = 3.575(9) Å. The closest Cs S is 3.772(3) Å.     

C-H⋯π(Ar)⋯Cl-C,C-Cl⋯π(Ar), Cl⋯Cl and other interactions in the crystal structure of 6-benzoyl-2,4-bis(trichloromethyl)-1,3-benzdioxin

The title compound is monoclinic,P2₁/n,Z=4,a=9.934(1),b=18.399(2),c=11.098(2)Å, =111.08(1)°. The molecule can conveniently be visualized as a benzophenone molecule with one of the aromatic rings fused to a 1,3-dioxin ring which adopts a distorted envelope conformation withcis-trichloromethyl groups substituted at positions 2 and 4. An interaction, observed for the first time, involves a hydrogen atom and a chlorine atom from opposite sides of the same aromatic ring to give C-H-(Ar)Cl-C. The parameters are Hring-centroid 2.63 A, Clring centroid 3.41 Å, Hring-centroidCl 167°, C-Hring centroid 159°, C-Clring centroid 150.2°. The (Ar) system is that of the unfused aromatic ring. A second (Ar) Cl-C interaction occurs but this time with the (Ar) system of the fused aromatic ring. The ClCl and ClO(=C) interactions form the familiar zig-zag pattern which has been noted for many chloroaromatic compounds.     

Cl⋯π(Ar), Cl⋯Cl,and other intermolecular interactions in the crystal structure of 8-nitro-6-methyl-2-trichloromethyl-4-dichloromethylene-1,3-benzodioxin

Crystals of the title compound are monoclinic,P2₁,a=9.791(4),b=7.129(3),c=10.428(3)Å,=91.84(3)°,V=727.50ų,Z=2. 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 of 0.045 using 2466 reflections. The molecules form stacks along theb axis of the formA, B, A, B(A=dichloromethylene group; B=aromatic ring in the molecule at –x, 1/2+y, –z to the molecule atx, y, z containing A). Cl(Ar),, ClCl, ClO(N), (Cl₃C)HO intermolecular interactions are also present. An inverse correlation between the (C)ClCl(C) distance and the difference in the corresponding pairs of C-ClCl angles is observed and is interpreted in terms of incipient nucleophile: electrophile attack.     

Crystal and molecular structure of tetra-n-butylammoniumbis(stilbenedithiolato)-nickelate(III)

The crystal and molecular structure of the title compound, C₄₄H₅₆NS₄Ni, are reported. Crystals are triclinic, space groupP¯1 (No. 2) withZ=2 in a unit cell of dimensionsa=8.874(2) Å,b=9.549(5) Å,c=26.025(7) Å,=97.22(3)°,=95.06(2)°, and=98.75(3)°. The structure was solved by Patterson and Fourier methods and refined by full-matrix least squares toR=0.062 for 2910 unique diffractometer data. The metal atom of the anion has an approximate square-planar configuration and the nitrogen atom of the cation an approximate tetrahedral configuration. The anions as well as the cations are well separated, the closest NiNi and NN approaches being the lattice repeat of 8.874(2) Å.     

Crystal structure of racemic 5-(p-nitrobenzoylamino)-5-methyl-4-oxo-1,3-dioxane

C₁₂H₁₂N₂O₆ crystallized from methanol in the monoclinic space group P2₁/c (Z=4) witha=13.333(4),b=10.154(3),c=9.597(2) Å and=102.37(2)°.M _r=280.24,V=1269.1(6) ų,D _x=1.466 g cm^–3,(Mo K)=0.71069 Å,=1.29 cm^–1,T=295 K. The structure was solved by direct methods and refined by full-matrix least-squares to a finalR (R _w)=0.049 (0.057) for 916 observed reflections. The molecules are linked by strong N-HO(4) hydrogen bonds with NO distance of 2.995(4) Å. The infinite racemic chains run in [001] direction.     

Crystal structure of 4,6-dinitro-1-(5-tetrazolyl)-1H-indazole trihydrate

The title compound, C₈H₄N₈O₄·3H₂O, crystallizes in space groupP¯1 with cell constantsa=7.022(1),b=9.507(2),c=10.906(2) Å,=84.99(1),=71.89(1),=72.56(1)°,Z=2, andV _c =660.2 ų. The structure was solved by direct methods using diffractometer data and was refined by full-matrix least-squares methods to anR value of 0.060 for 2112 observed reflections. The molecule, consisting of a phenyl ring fused to a pyrazole ring with a tetrazole ring connected to it equatorially, is planar except for the N(7) nitro-group oxygen atoms. The structure is stabilized by a three-dimensional network of O-HO, O-HN, and N-HO hydrogen bonds through the water molecules.     

Two acetylamino derivatives of 2,4-bis(trichloromethyl)-1,3-benzdioxin showing different types of hydrogen bonding: (a) (C13C)CH⋯O=C and (b) N-H⋯O=C

8-Acetylamino-6-methyl-2,4-bis(trichloromethyl)-1,3-benzdioxin, (I), is monoclinic,P2₁/c,a=15.174(4),b=11.977(7),c=9.911(3)Å,=99.72(2)°. 6-Acetylamino-2,4-bis(trichloromethyl)-1,3-benzdioxin, (II), is monoclinic,P2₁/_n,a=5.927(4),b=40.623(1),c =7.120(3)Å,=91.39(4)°. In compound (I) the imino hydrogen atom is locked in an intramolecular hydrogen bond to the proximate oxygen atom of the heterocyclic ring and is not available for intermolecular hydrogen bonding. Instead the weakly acidic hydrogen atom [Cl₃C-C(2)]H takes part in a hydrogen bond to the carbonyl oxygen atom in another molecule. In compound (II) a normal intermolecular hydrogen bond of the type N-HO=C occurs. The 6-acetylam-ino group is twisted about the (C_Ar-N) bond such that the angles NHO=C, C_ArH_ArO=C, NHOH_ArC_Ar, at the carbonyl oxygen group total 360° (where NH is in the related molecule). The packing in both compounds takes the form of infinite chains and in compound (II) partial overlap of the aromatic ring and the acetylamino group, with very little offset, also occurs.     

Structure and spectroscopic properties of the 1∶2 complex of 3,5-dimethylpyridine with 3,5-dinitrobenzoic acid and its deuterated analog

The structure of the nondeuterated and deuterated complexes of 3,5-dimethylpyridine with 3,5-dinitrobenzoic acid in a stoichiometric ratio 12 have been determined by X-ray diffraction methods. The crystals of the nondeuterated complex are triclinic, space groupP¯1 witha=9.409(9),b=10.813(7),c=12.310(7)Å,a=95.75(5),=108.17(7), =91.46(7)° andZ=2. The crystals of the deuterated complex are monoclinic, space groupP2₁/c, witha=11.680(6),b=8.451(4),c=24.382(9)Å,=102.94(4)° andZ=4. Both structures have been solved by direct methods and refined toR=0.035 for 2235 and toR=0.044 for 1938 independent reflections for nondeuterated and deuterated crystal, respectively. The structures consist of 3,5-dimethylpyridinium cations and hydrogen (or deuterium) bis(3,5-dinitrobenzoate) anions. The N(1)⁺-H(N1)O(1)^–, O(7)-H(7)O(2), N(1)⁺-D(1)O(l)^– and O(7)-D(7)O(2) bond lengths are 2.644(4), 2.499(3), 2.739(5), and 2.526(5)Å, respectively. The IR spectra of both complexes within the proton (or deuteron) absorption range have been studied.     

Crystal structure of a nucleoside analogue, 2′,3′-dideoxy-3′-fluoro-5-chlorocytidine

The title compound, 1-(2,3-dideoxy-3-fluoro--d-erythro pentofuranos-1-yl)-5-chlorocytosine, crystallises in the orthorhombic space groupP2₁2₁2₁ witha=5.142(1),b=14.177(2),c=15.721(2) Å,Z=4. The crystal structure was solved by the heavy atom method and refined by full-matrix least-squares method to a finalR value of 0.031 for 1629 unique observed reflections. The N-glycosidic torsion angle is –156.1(2)° and the sugar moiety is anti to the cytosine base. The sugar pucker is ₂ ³ T withP=178.2(1)° and=31(1)°. The atom 05 is in a +sc conformation with respect to the furanose ring. The molecular packing in the crystal is stabilized by N-HN, N-HO, O-HO hydrogen bonds and C-HO close contacts.     

Crystal and molecular structure of 4-p-hydroxyphenyl-2,2,4-trimethylthiachroman-1,1-dioxide

The title compound1 crystallizes as colorless polyhedra in the monoclinic polar space groupCc, witha=8.107(2),b=21.577(3),c=9.542(2)Å,=103.58(2)°, by contrast with its thioether precursor3, crystals of which have the trigonal space groupR¯3. The structure comprises infinite chains of molecules linked head-to-tail by S=OHO hydrogen bonds of length 2.723(2)Å, with HO contact 1.97(4)Å and O-HO 177(3)°; HÔ=S 146(1)°.     

Hydrogen-bonded coordination network in crystal structures of [Cu(3-PM)4Cl2] and [Cu(4-PM)4Cl]Cl, (PM = pyridylmethanol)

The crystal and molecular structures of [Cu(3-PM)₄Cl₂] (1) and [Cu(4-PM)₄Cl]Cl (2) have been determinated by X-ray crystallography. Complex 1 crystallizes in the triclinic system, space group P–1, with lattice parameters a = 7.972(2) Å, b = 8.293(2) Å, c = 10.707(2) Å, = 105.73(3)°, = 90.04(3)°, = 110.38(3)°, and Z = 1 at 100 K. The coordination geometry of each Cu atom is approximately octahedral formed by four nitrogen atoms of pyridine rings of 3-pyridylmethanol molecules in the equatorial plane and two chlorine atoms occupying the axial positions. The O—HsO, C—HsCl, and O—HsCl intermolecular hydrogen bonds and s stacking link the molecules in 3-D hydrogen-bonded coordination network. Complex 2 crystallizes in the tetragonal system, space group P4/n, with lattice parameters a = 10.464(1) Å, c = 11.339(2) Å, and Z = 2 at 217 K and a = 10.352(1) Å, c = 11.201(2) Å, and Z = 2 at 293 K. The coordination geometry of Cu atom in the [Cu(4-PM)₄Cl]⁺ ion is approximately square pyramidal formed by four nitrogen atoms of pyridine rings of 4-pyridylmethanol molecules in equatorial plane and one chlorine atom in axial position. The O—HsCl and C—HsCl intermolecular hydrogen bonds link the molecules in 2-D hydrogen-bonded coordination network.     

Structure of fruticuline B: A new natural anthracene quinodimethide of abietanoid origin

The title compound is C₁₉H₁₈O₄·1/2 CH₃OH, triclinic,P¯1,a=9.891(2),b=13.273(4),c=13.860(4) Å,a=66.47(2),=86.91(2), and =85.59(2)°. The structure was solved by direct methods and refined by least-squares techniques to anR factor of 0.082 for 2282 observed reflections. The X-ray structure uniquely resolves the one remaining ambiguity, namely the assignment of the correct structure4. There are two crystallographically independent molecules (A and B) and one disordered methanol molecule. Both molecular skeletons show small distortions from planarity with inclinations of 1.7 and 4.0° between the outermost rings A/C in molecules A and B, respectively. Intramolecular hydrogen bonds of the form O(3A)-HO(2A) and O(3B)-HO(2B) are observed in molecules A and B, respectively. The molecules are linked by pairs of O(3A)-HO(2B) and O(3B)-HO(2A) hydrogen bonds. The dimerlike structures are stabilized by intermolecular C-HO interactions and van der Waals forces.     

Crystal and molecular structure ofp-aminobenzene sulfonacetamide sodium [sulfacetamide sodium] monohydrate

The crystal and molecular structure ofp-aminobenzene sulfonacetamide sodium, C₈H₉N₂NaO₃S·H₂O, an important substituted sulfa drug, has been determined from diffractometric data using MoK radiation. The crystals are monoclinic, witha=6.614(2),b=23.788(6),c=7.012(2) Å,=103.13(2)°, and space groupP2₁/c. The structure was solved by the heavyatom method, and refined by full-matrix least squares to a finalR value of 0.040 with 1435 unique reflections. In packing, the molecules form dimers through pairs of N-HN and N-HO hydrogen bonds. The molecules are further stabilized by O-HO and O-HN hydrogen bonds.     

Crystal structure of a nucleoside analog, 2′,3′-dideoxy-3′-azido-5-chlorocytidine

The title compound, l-(2,3-dideoxy-3-azido--D-erythro pentofuranos-1-yl)-5-chlorocytosine, crystallizes in the orthorhombic space groupP2₁2₁2₁ witha=5.840(1),b=13.780(1),c=15.396(2)Å,Z=4. The structure was solved by direct methods and refined by full-matrix least-squares calculations to a finalR value of 0.033 for 1688 unique observed reflections. The N-glycosidic torsion angle has a value of –160.8(1)°, in the and range. The sugar pucker is ₂ ³ T withP=180(1)° and=34(1)°. The C4–C5 conformation is +sc with =50.8(2)°. The azido group is nonlinear and oriented trans to the C3–C4 bond. The molecular packing in the crystalline space is stabilized by N-HN, N-HO, O-HO hydrogen bonds and C-HO close contacts.     

Structure of 5-benzoylamino-5-methyl-4-oxo-1,3-dioxane

The crystals of the title compound (C₁₂H₁₃NO₄) are orthorhombic,P2₁2₁2₁ witha=8.541(3),b=10.988(1), andc=11.912(1) Å.M _r =235.24, mp 427 K,Z=4,D _x =1.348 Mg m^–3, (MoK=0.71069 Å, =0.11 mm^–1,T=293 K. The structure was solved by direct methods and refined by full-matrixs least squares to a finalR=0.028 for 1180 observed reflections. The molecules are connected by N-HO (ring carbonyl) intermolecular HO hydrogen bonds of 2.24(2) Å. The 4-oxo-1,3-dioxane ring is in a slightly distorted sofa conformation with a C _s ¹ asymmetry parameter of 3.6(2)° and the 5-methyl substituent in a pseudoaxial position. The benzoyl oxygen is turned toward the ring, resulting in a close OH(C6) contact of 2.45(2) Å.     

Crystal and molecular structure of 3-dimethylaminobenzoic acid

The title compound C₉H₁₁NO₂ is triclinic, space group P¯1, with the cell dimensionsa=7.022(1),b=7.476(2),c=8.957 (1) Å,=87.02(2),=110.88(1),=99.10(1)°,V=433.8(4) ų,Z=2,M _r =165.2,Do=1.27,Dx=1.26 mg/m³,F(000)=176,T=293 K,R=0.057 for 939 observed reflections. The molecules are packed as centrosymmetric hydrogen bonded dimers with an O-HO distance of 2.626(3) Å. The COOH group is rotated by 1.7(1)° about the exocyclic C(1)-C(7) bond out of the benzene ring plane. The molecules lie on (0 2-1) plane for which thed value is found to be 3.378 Å which is very close to the mean separation between the parallel packed benezene rings [3.347(4) Å]. The entire molecule is planar except for the two methyl groups attached to the nitrogen atom. The N atom is free from any binding of either type C-HN or O-HN.N. C. L. Communication No. 4699.     

Hydrogen bonding in 2-hydroxy((di)thio)benzoates. III. IR and NMR spectra of 2,6-dimethylpiperidinium and tetraethylammonium salts

Solid state ir and solution ir and nmr data are reported for 2,6-dimethylpiperidinium and tetraethylammonium salts of 2-hydroxybenzoic, 2-hydroxythiobenzoic and 2-hydroxydithiobenzoic acid. The solid state ¯v(OH) frequencies, range from 2800 to 2300 cm^–1 and decrease within the series thiocarboxylate (O-HO)>dithiocarboxylate (O-HS)>carboxylate (O-HO)>thiocarboxylate (O-HS), reflect the different kinds of intramolecular O-HY association. The solution ¯v(OH) frequencies range from 2830 to 2560 cm^–1 and decrease within the series thiocarboxylate>dithiocarboxylate>carboxylate; the (OH) proton shifts range from 12.8 to 16.0 ppm and correspondingly increase within the same series. IR and NMR data give confident evidence for an O-HO intramolecular association of the thiocarboxylate anions in solution.     

Molecular structure and some reactivity aspects of 2,6-diamino-4(3H)-pyrimidinone monohydrate

Crystals of C₄H₆N₄O·H₂O are orthorhombic:Pbca,a=16.721(2),b=4.242(1),c=18.293(2)Å,Z=8. The structure has been solved by direct methods and refined by full-matrix least-squares techniques toR=0.046 for 1252 unique reflections. The structure consists of approximately planar molecules of the 3(H)4-one tautomer. Delocalization of the ring and the C=O-electrons, and conjugation of the lone-pair electrons of the amine groups with the pyrimidinone nucleus are observed. The molecules are connected by O-HO, N-HN, and N-HO hydrogen bonds. The molecular structure clarifies the chemical properties of the compound.     

Crystal structures of two therapeutically active 2-imidazolines: naphazoline nitrate and tymazoline hydrochloride monohydrate

Naphazoline·HNO₃ (1): C₁₄H₁₅N₃O₃,M _r =273.3, crystallizes in the orthorhombic space group Pbca(Z=8) witha=12.028(1),b=14.408(2) andc=15.894(2) Å,V=2754.4 ų,D _x =1.318 g cm^–3,=0.70 mm^–1, (CuK)=1.54178 Å,F(000)=1152. FinalR=0.092 andwR=0.088 for 1348 observed reflections collected on a diffractometer. The structure was solved with direct methods, it shows two distinct positions of the naphthyl group with populations about 0.5, which differ by a 180 rotation. As in other arylmethyl-2-imidazolines, the imidazoline ring is approximately perpendicular to the aromatic ring. The molecules are linked by two hydrogen bonds N(3)-HO (nitrate anion)H-N(1) into infinite chains running along the 2₁ axis in the [100] direction. Tymazoline·HC1·H₂O (2): C₁₄H₂₃ClN₂O₂,M _r =286.8, crystallizes in the monoclinic space groupP2₁/n (Z=4) witha=8.136(1),b=10.015(1),c=18.601(1) Å and,=97.20(1)°,V=1503.7 ų D _x =1.266 g cm^–3,=2.27 mm^–1, (CuK)=1.54178 Å,F(000)=636. FinalR=0.115 andwR=0.119 for 3073 observed reflections collected on a diffractometer. The structure was solved with direct methods. Unlike other aryloxymethyl-2-imidazolines, the molecule is almost planar with an angle of 12.8(2)° between the two rings. Hydrogen bonding networks consist of N(1)-HO (water)Cl^–H-N(3) chains joined by an additional link O(water)-HCl^– between chains running in opposite directions.