Polymorphs of nitrofurantoin. I. Preparation and X-ray crystal structures of two monohydrated forms of nitrofurantoin

The preparation and X-ray crystal structures of two monohydrates of the antibacterial drug nitro furantoin are reported. MonohydrateI crystallizes in the monoclinic space groupP2₁ n and monohydrateII in the orthorhombic space group Pbca. The nitrofurantoin molecule maintains the same, planar conformation in both crystals. The molecular packing arrangements inI andII are distinctly different,I possessing a layer structure while inII the packing is based on a herring bone motif. Hydrogen bonds of the type O-HO, N-HO, O-HN and C-HO stabilize the crystal structures.     

Crystal structures of two allotropic forms of Na2CoP2O7

Na₂CoP₂O₇ may be prepared in two allotropie forms:I, rose,M _r =278.85, triclinic, P1,a=9.735(2),b=10.940(3),c=12.289(4) Å,=148.78,=121.76(1), =68.38(2)°,V=566.8(2) ų,Z=4,D _meas=3.28(5) g cm^–3,D _calc=3.267 g cm^–3, (MoK)=0.71069 Å,=37.12 cm^–1, F(000)=540,T=298 K,R=5.4% for 2911 observed reflections; andII, blue,M _r =278.85, orthorhombic, P2₁cn,a=7.713(2) Å,b=10.271(4),c=15.378(6)°,V=1218.2(8) ų,Z=8,D _meas=3.06(5) g cm^–3,D _calc=3.040 g cm^–1, (MoK ) Å,=34.55 cm^–1, F(000)=1080,T=298 K,R=9.9% for 1450 observed reflections. Cobalt displays octahedral coordination to six oxygen atoms in the rose form whereas the metal coordination is tetrahedral in the blue form.     

Crystal structures of two forms of pentachloropyridine

Tetragonal and monoclinic forms of crystalline pentachloropyridine are described. Both forms may be regarded as layer structures. The basic layer common to the two structures has neighbouring molecules in the same orientation. The tetragonal form has a repeat unit of four layers, whereas the monoclinic form has a repeat unit of two layers. The packing of adjacent layers is essentially the same for both forms.Examples have been found in which the stacking sequences are interrupted, producing faults, twins and diphasic crystals.     

Syntheses and crystal structures of two N-substituted thio-imidazoles

The syntheses and structures of two N-substituted thio-imidazoles are reported. The geometrical parameters for both compounds, including essentially planar imidazole rings, are consistent with previous structural studies of related materials. The only possible non-van der Waals’ interactions influencing the molecular packing are weak C–H⋯π bonds. Crystal data: C₁₂H₁₄N₂S (N-methyl-N′-2-phenylethyl-imidazol-2-thione), M _r = 218.31, monoclinic, P2₁/n, (No. 14), a = 6.8441(2) ?, b = 12.9960(4) ?, c = 13.4703(4) ?, β = 97.7729(16)°, V = 1187.12(6) ?³, Z = 4, R(F) = 0.039, wR(F ²) = 0.104. C₁₉H₂₀N₂S (N,N′-bis((s)-1-phenylethyl)imidazol-2-thione), M _r = 308.43, orthorhombic, P2₁2₁2₁ (No. 19), a = 10.4060(3) ?, b = 10.6712(3) ?, c = 14.8932(3) ?, V = 1653.81(7) ?³, Z = 4, R(F) = 0.038, wR(F ²) = 0.085.     

Syntheses and crystal structures of two soybean isoflavone derivatives

Two soybean isoflavone derivatives, 7-methoxy-4′-hydroxyisoflavone (1) and 4′, 7-diethoxyl-5-hydroxyisoflavone (2) were synthesized and their crystal structures were determined by single-crystal X-ray diffraction. Two derivatives crystallize in the monoclinic crystal system, space group P2₁/c. The cell dimensions of 1 are a = 8.696(4) Å, b = 11.947(5) Å, c = 12.078(5) Å, β = 93.594(7)^∘, D_c = 1.423 Mg/m³, V = 1252.3(10) ų, Z = 4, and those of 2 are a = 37.672(12) Å, b = 11.228(4) Å, c = 7.582 (3) Å, β = 94.150(6)^∘, D_c = 1.355 Mg/m³, V = 3198.6(18) ų and Z = 8. They have the same isoflavone skeleton which is composed of a benzopyranone moiety and a phenyl moiety. Hydrogen bonding and π < eqid1 > π stacking interactions assemble 1 into supramolecule with a three-dimensional network. And in the crystal structure of 2, hydrogen bonding and C–H ⋅s π stacking interactions lead to the formation of a two-dimensional network.     

X-ray crystal structure of 2-styrylpyridine

We have crystallized the 2-styrylpyridine from the condensation reaction between the 2-methylpyridine with benzaldehyde in the formation of the model compound 2-styrylpyridine. The X-ray structure and NMR are currently reported. The main features of the structure is that is shows a localization of the double bonds rather than a delocalization of π electrons in an aromatic fashion.     

X-ray crystal structure of 2-styrylpyridine

We have crystallized the 2-styrylpyridine from the condensation reaction between the 2-methylpyridine with benzaldehyde in the formation of the model compound 2-styrylpyridine. The X-ray structure and NMR are currently reported. The main features of the structure is that is shows a localization of the double bonds rather than a delocalization of π electrons in an aromatic fashion.     

Palladium(II) complexes of N2O2 and N2S2 ligands: Syntheses and X-ray crystal structures

Palladium(II) complexes of an imine-thiophene ligand N,N bis(1-methylenethiophene)-1,3-diaminopropane and an amine-phenol ligand N,N-bis(2-hydroxybenzyl)1,3-diamino-2,2-dimethylpropane were synthesized by reacting K₂PdCl₄ with alcoholic solutions of the ligands. X-ray structures of the complexes were determined using data from a CAD-4 Nonius diffractometer (MoK radiation). The structures were solved by conventional methods resulting inR factors of 0.044 and 0.061 using 1841 and 2241 independent reflections, respectively. Crystal data: Complex I, orthorhombic, space groupPbca,a=11.323(2),b=14.819(2),c=23.873(3)Å,V=4006(1)ų,Z=8. Complex II: Space groupP2₁/c,a=9.169(2),b=31.920(4),c=8.902(6),=90.38(2)°,V=2605(1)ų.Z=4. Both complexes showed coordination of the ligands through the nitrogens only while the sulphur and the oxygen atoms were uncoordinated. Square planar coordination is completed bycis chloro ligands.Deceased.     

X-ray diffraction and vibrational spectra of the guanidine:maleic acid (1:1) complex—two crystal forms

From an equimolar mixture of guanidine and maleic acid, two different crystal modifications of guanidinium hydrogen maleate, CH₆N ₃ ⁺ ·C₄H₃O ₄ ^– , were isolated and their crystal structures determined using three-dimensional diffractometer data. Crystals of both forms are orthorhombic:Pca2₁,a=19.012(8)b=3.758(1),c=11.119(5) Å,Z=4 for form I;Fdd2,a=18.505(2),b=20.007(3),c=8.406(2) Å,Z=16 for form II. The structures were solved by direct methods and refined by full-matrix least squares to conventionalR values of 0.064 for form I and 0.043 for form II, with 488 and 605 reflections respectively. The structures consist of planar guanidinium cations C(NH₂) ₃ ⁺ and hydrogen-maleate residues C₄H₃O ₄ ^– . There are no significant differences in distances and angles within the guanidinium and hydrogen-maleate units. However, a substantial difference appears in the length and geometry of the intramolecular hydrogen bond OHO. The packing of cations and anions is also completely different in the two forms. Infrared and Raman spectra of the title compound are presented, and salient differences between them and the spectrum of the symmetrically bonded potassium hydrogen maleate are discussed briefly.     

X-ray structures of two methoxybenzo[b]thiophenes

The crystal and molecular structures of two methoxybenzo[b]thiophenes have been determined by three-dimensional, single-crystal X-ray diffractometry. Both 3-(4-hydroxy-3, 5-dimethoxybenzoyl)-2-(4-methoxyphenyl)-6-methoxybenzo[b]thiophene and 3-(2,6-dimethoxybenzoyl)-2-(4-methoxyphenyl)-6-methoxybenzo[b]thiophene (hereafter referred to asI andII, respectively) crystallize in the monoclinic centrosymmetric space groupP2₁/n (No. 14, C _2h ⁵ ) with four formula units-per cell witha=6.866(1),b=28.638(2),c=11.830(2) Å, and =105.52(1)° anda=9.328(1),b=7.977(1),c=29.650(4) Å, and =97.87(1)°, respectively. The phase problems were solved by direct methods and the respective final full-matrix least-squares refinements converged toR=0.046 and 0.031. The structures differ in the positioning of the dimethoxy groups of the benzoyl ligands and the addition of a hydroxyl group inI. The molecules in the crystal lattice are held together by van der Waals forces plus the addition of hydrogen bonding in compoundI. Selected bond distances and angles and torsion angles are tabularized.     

Molecular and crystal structures of N-methyl-N-nitro-2-chloroaniline

The crystal structure of N-methyl-N-nitro-2-chloroaniline is determined by X-ray diffraction [a = 9.218(2) Å, b = 12.593(3) Å, c = 14.510(2) Å, space group Pbca, and Z = 8]. The structure is solved by the direct method and refined in the anisotropic approximation to R = 0.0377. All hydrogen atoms are localized. The structural parameters obtained agree with the data of the ab initio quantum-chemical B3LYP/6-31G** calculations. The data obtained are compared with those for N-methyl-N-nitro-4-chloroaniline. Conclusions on the interaction of the functional groups in the molecule are drawn.     

Syntheses and crystal structures of two isomeric pyrazoles with ferrocenyl groups

Ferrocenoylacetone I reacts with terephthaloyl hydrazide in the presence of a catalytic amount of p-toluenesulfonic acid to afford complex 1 whereas acylation of 3(5)-ferrocenyl-5(3)-methylpyrazole II with terephthaloyl chloride leads to an isomer of complex 1, viz. complex 2. Two new complexes have been characterized by elemental analyses and IR,¹H NMR, UV spectra and structurally characterized by single-crystal X-ray crystallography. Complex 1 (C₃₆H₃₀Fe₂N₄O₂) crystallizes in the monoclinic space group P2₁/c, with lattice constants: a = 11.593(2) ?, b = 12.9962(17) ?, c = 10.0030(17) ?, β = 113.227(4)°, V = 1462.1(4) ?³, Z = 4, D _c = 1.505 g·cm⁻³, F(000) = 684, R ₁ = 0.0307, wR ₂ = 0.0739. Complex 2 (C₃₆H₃₀Fe₂N₄O₂) crystallizes in the monoclinic space group P2₁/n, with lattice constants: a = 12.2388(18) ?, b = 7.3200(15) ?, c = 17.288(4) ?, β = 90.89(3)°, V = 1466.9(5) ?³, Z = 2, D _c = 1.500 g·cm⁻³, F(000) = 684, R ₁ = 0.0410, wR ₂ = 0.1247. Supplementary material Full crystallographic data (CCDC No. 602174 for complex 1 and CCDC No. 602175 for complex 2) have been deposited at the Cambridge Crystallographic Database Centre and are available on request from the Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (Fax: +44-1223-336-033; Email:deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).     

X-ray structures of fifty year old crystals of cholesterol iodide forms I and II

  The molecular framework of steroids was firmly established from the successful X-ray analysis of cholesteryl iodide crystals over fifty years ago. At the time, this was a triumph for the rapidly developing technique of X-ray crystallography. We describe here new analyses of cholesteryl iodide using crystals of forms I and II^(A) which are at least 50 years old. Comparison of these two structures reveals subtle differences in the geometry of the steroid skeleton, the attached side chain and the covalently bound iodine. The crystals of both forms occur in the same monoclinic space group, P2₁, with similar but nevertheless different unit cells, particularly in the b-axis length. As a consequence, there are subtle differences in the packing mechanisms of the two polymorphs. The two forms were originally classified by Bernal and Crowfoot, on the basis of their studies of more than 60 crystals of sterols and sterol derivatives, as “normal, type A - the common form” (corresponding to form II) and “reverse or type B” (corresponding to form I), respectively. Those crystals of form I which have survived for almost 55 years are poor X-ray diffractors at room temperature and have been analysed at liquid N temperature, diffracting well under these conditions. Form II crystals diffract well at room temperature and for this reason the crystals were not cooled. The main differences in geometry occur in the side-chain which is disordered in the room temperature form II crystals, whilst the individual ring conformations in the steroid skeleton are similar, ring A being a strained chair, ring B a 7α/8β half-chair, ring C a symmetrical chair and D a 13β/14α half-chair. (A) Originally denoted Forms B and A respectively. See Additional Note (A) for explanation.

The stereochemistry of organosulfur compounds. XX. The x-ray crystal and molecular structures of two tetrathiaspiroalkanes

The X-ray crystal structures of 1,4,6,9-tetrathiaspiro[4.4]nonane (4) and 1,5,7,11-tetrathiaspiro[5.5]undecane (3) have been determined. Crystals of4 are tetragonal, space groupI4₁ cd, with eight molecules in a unit cell of dimensionsa=9.521 (2) andc=19.052(5) Å. Crystals of3 are orthorhombic,Pbca, with eight moleucles in a cell havinga=8.955(3),b=12.356(4), andc=18.425(4) Å. Compound4 was solved from the Patterson map and3 by use ofMultan, and they refined to finalR values of 6.4 and 2.5%, respectively. Compound4 consists of two 1,3-dithiolane rings connected via C(2), both of which appear to be somewhat disordered at room temperature. The uncorrected C-C distance is 1.476 Å and the average S-C distance is 1.786 Å. Compound3 consists of two 1,3-dithiane rings connected at C(2), both in chair conformations. In both compounds there appear to be electronic repulsions between S lone pairs and axial hydrogens of the opposite ring system. Analysis of endocyclic torsion angles in3 indicates that the ring conformations themselves are not significantly altered by the positional shift caused by the repulsion.     

X-ray crystal structures of new chiral enaminones from 2,4-pentanedione and their heterocyclic derivatives

New chiral enaminones from 2,4-pentanedione (1, 4) and their 1,4-oxazepinium and 1,4-thiazepinium derivatives (5–7) were synthesized and their crystal structures were determined by single crystal X-ray diffraction studies. The crystallographic data for these compounds are as follows: (R)-(1-Methyl-3-oxo-but-1-enylamino)-phenylacetic acid methyl ester (1): a = 7.574(1) ?, b = 12.530(1) ?, c = 14.245(1) ?, P2₁2₁2₁. (R)-4-(2-hydroxy-1-phenyl-ethylamino)-pent-3-en-2-one (2): a = 5.543(1) ?, b = 9.433(1) ?, c = 12.237(2) ?, β = 100.687(3)°, P2₁. (2S, 3R)-3-hydroxy-2-(1-methyl-3-oxobut-1-enylamine) butyric acid methyl ester (3): a = 5.583(1) ?, b = 8.660(1) ?, c = 12.149(1) ?, α = 92.85(1)°, β = 91.00(1)°, γ = 90.16(1)°, P1. (R)-3-[2-Methoxycarbonyl-2-(1-methyl-3-oxo-butylideneamino)-ethyldisulfanyl]-2-(1-methyl-3-oxo-butylideneamino)-propionic acid methyl ester (4): a = 9.309(1) ?, b = 11.460(1) ?, c = 11.310(1) ?, β = 112.582(2)°,P2_1.(3R)-5,7-dimethyl-3-phenyl-2,3-dihydro-[1,4]oxazepinium trifluoroborate (5): a = 8.958(1) ?, c = 18.085(1) ?, P4₃. (2S, 3R)-3-methoxycarbonyl-2, 5,7-trimethyl-2, 3-dihydro-[1,4] oxazepin-4-ium trifluroborate (6): a = 8.626(1) ?, b = 11.597(1) ?, c = 13.733(19) ?, P2₁2₁2₁. 3-Methoxycarbonyl-5, 7-dimethyl-2, 3-dihydro- [1,4]-thiazepin-4-ium trifluoroborate (7): a = 13.737(1) ?, b = 6.244(1) ?, c = 16.041(1) ?, β = 104.927(2)°, P2₁/n.     

Molecular structures and crystal packings of 2-styrylquinoxaline derivatives

The crystal and molecular structures of 2-styrylquinoxaline derivatives with different substituents in the styryl fragment are determined. The degree of planarity of the molecules studied varies in a very wide range, from 1.7° to 33.5°. In the ethylene fragment, the double bond is essentially localized. The bicycle-pedal disordering of the ethylene fragment is found in the crystals of the methoxy and oxyacetyl derivatives of 2-styrylquinoxaline. None of the packings contains packing motifs favorable for the photocycloaddition (PCA) reaction with single crystal retention. The crystal packings of these compounds and that of 2-(4-methylstyryl)quinoxaline are characterized by a stacking motif of the head-to-head type, which eliminates the possibility of PCA taking place with single crystal retention but is suitable for this reaction in polycrystalline films. The crystal packing of 2-(3,4-dimethoxystyryl)quinoxaline does not contain elements with stacking interactions.     

The crystal and molecular structures of rac-threo-ifenprodil and two other 4-benzylpiperidinyl derivatives

The crystal structures of threo-ifenprodil [threo-2-(4-benzyl-piperidin-1-yl)-1-(4-hydroxyphenyl)-propan-1-ol] (1), potent NMDA receptor antagonist, and two related, biologically active compounds: threo-2-(4-benzyl-piperidin-1-yl)-1-(4-fluorophenyl)-propan-1-ol (2) and 4-benzyl-1-phenethyl-piperidinium chloride (3) have been determined by X-ray structure analysis of single crystals. Compound 1 crystallizes in an orthorhombic system, with a space group Pna2₁ (a = 34.843(3) Å, b = 6.0261(13) Å, c = 8.9343(9) Å), compound 2 – in a monoclinic space group P2₁/c (a = 14.194(1) Å, b = 6.2831(6) Å, c = 20.948(1) Å, = 101.762(6)), and compound 3 – in an orthorhombic space group Pbca (a = 10.4627(8) Å, b = 11.2166(6) Å, c = 31.669(2) Å). The piperidine rings are close to ideal chair conformations, the substituents are in equatorial positions. Overall shapes of the molecules, defined by the dihedral angles between the terminal aromatic rings, are very similar in all three cases. In 1 and 3 the crystal packing is mainly determined by the hydrogen bonds, while in case of 2 – by weak van der Waals interactions. The molecules of 1 and 3 are disordered, and the disorder is caused by a rotation around the N–C bond.     

A method for automated determination of the crystal structures from X-ray powder diffraction data

An algorithm is proposed for determining the crystal structure of compounds. In the framework of this algorithm, X-ray powder diffraction patterns are compared using a new similarity index. Unlike the indices traditionally employed in X-ray powder diffraction analysis, the new similarity index can be applied even in the case of overlapping peaks and large differences in unit cell parameters. The capabilities of the proposed procedure are demonstrated by solving the crystal structures of a number of organic pigments (PY111, PR181, Me-PR170).     

Molecular structures and crystal packings of 2-styrylquinoline and its derivatives

The crystal and molecular structures of five styrylheterocycles of the quinoline series are studied. All molecules are planar. The double bond in the ethylene fragment is essentially localized. In the molecule of 2-(4-methylstyryl)quinoline, the ethylene fragment is disordered by the bicycle-pedal pattern. In four of the five compounds, the crystal packings do not contain stacking dimers prearranged for the [2+2] photocycloaddition (PCA) reaction. In the crystal of 2-(3-nitrostyryl)quinoline, pairs of crystallographically independent molecules form stacking dimers. In a dimer, the ethylene fragments have a twist orientation, which is incompatible with the PCA reaction. An attempt to initiate a temperature-dependent process of bicyclepedal isomerization in the crystal and, as a consequence, the PCA reaction by means of simultaneous irradiation and heating of a single crystal is unsuccessful.