共查询到20条相似文献,搜索用时 140 毫秒
1.
Gang Xue Qi Fang Wentao Yu 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(11):o653-o655
4,5‐Propylenedithio‐1,3‐dithiole‐2‐thione, C6H6S5, (I), crystallizes in the centrosymmetric space group P21/c. The molecular packing is characterized by pairs of S⋯S intermolecular contacts between neighbouring molecules, which may account for the rather high thermal stablity of the crystal. 4,5‐Propylenedithio‐1,3‐dithiol‐2‐one, C6H6OS4, (II), in which an O atom replaces the terminal S atom of (I), crystallizes in the non‐centrosymmetric polar space group Cc. The packing pattern of (II) indicates that the macropolarization direction is along [101]. Although the packing patterns are qualitatively significantly different, the molecular structures of (I) and (II) are similar, each exhibiting a chair conformation. 相似文献
2.
Natalya Fridman Moshe Kapon Menahem Kaftory 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):o47-o49
5‐Methylsulfanyl‐1H‐tetrazole, C2H4N4S, crystallizes in dimorphic forms; the α‐form crystallizes at room temperature in the monoclinic crystal system, space group P21/m, and the β‐form crystallizes by sublimation at 423 K in the orthorhombic crystal system, space group Pbcm. In both forms, the molecules occupy crystallographic mirror planes and are connected to one another via N—H⋯N hydrogen bonds, the amino H atoms being disordered. The two forms differ from one another in their packing; there are polar layers in the α‐form and non‐polar layers in the β‐form. 相似文献
3.
Bernard Omondi Demetrius C. Levendis Marcus Layh Manuel A. Fernandes 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(9):o470-o475
The structures of two distinct polymorphic forms of N‐(2,6‐difluorophenyl)formamide, C7H5F2NO, have been studied using single crystals obtained under different crystallizing conditions. The two forms crystallize in different space groups, viz. form (Ia) in the orthorhombic Pbca and form (Ib) in the monoclinic P21 space group. Each polymorph crystallizes with one complete molecule in the asymmetric unit and they have a similar molecular geometry, showing a trans conformation with the formamide group being out of the plane of the aromatic ring. The packing arrangements of the two polymorphs are quite different, with form (Ia) having molecules that are stacked in an alternating arrangement, linked into chains of N—H...O hydrogen bonds along the crystallographic a direction, while form (Ib) has its N—H...O hydrogen‐bonded molecules stacked in a linear fashion. A theoretical study of the two structures allows information to be gained regarding other contributing interactions, such as π–π and weak C—H...F, in their crystal structures. 相似文献
4.
Manuela Müller Hans‐Wolfram Lerner Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(8):796-800
2,5‐[(Diphenylphosphanyl)methyl]‐1,1,2,4,4,5‐hexaphenyl‐1,4‐diphospha‐2,5‐diboracyclohexane shows polymorphism as two tetrahydrofuran (THF) disolvates [C64H58B2P4·2C4H8O, (Ia) and (Ib)] and pseudo‐polymorphism as its toluene monosolvate [C64H58B2P4·C7H8, (Ic)]. In each of polymorphs (Ia) and (Ib), the diphosphadiboracyclohexane molecule is located on a centre of inversion. The THF molecule of (Ib) is disordered over two sites, with a site‐occupation factor of 0.612 (8) for the major‐occupied site. Both structures crystallize in the same space group (P21/n), but they display a different crystal packing. For pseudo‐polymorph (Ic), although the space group is P21/c, which is just a different setting of the P21/n space group of (Ia) and (Ib), the crystal packing is completely different. Although the crystal packing in these three structures is significantly different, their molecular conformations are surprisingly the same. 相似文献
5.
Daniel E. Lynch Gillian E. Spicer Ian McClenaghan 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):o715-o718
The structures of 2‐phenylmalonpiperadide [systematic name: 2‐phenyl‐1,3‐bis(piperidin‐1‐yl)propane‐1,3‐dione, C19H26N2O2, (I)] and 2‐phenylmalonmorpholide [systematic name: 1,3‐dimorpholino‐2‐phenylpropane‐1,3‐dione, C17H22N2O4, (II)], have been determined and both their molecular conformations and packing arrangements compared. Although chemically similar, compounds (I) and (II) exhibit different molecular conformations. The only general conformational similarities are that their respective carbonyl groups are orientated in the same direction and the heterocyclic rings exist in the chair arrangement. General similarities in the packing arrangements arise due to both compounds having the same space group (P212121) and a similar alignment of their phenyl‐substituted backbone with respect to the c axis. Similar C—H⋯O hydrogen‐bonding associations are listed for the carbonyl O atoms, while only one of the morpholine O atoms is involved in any such association. 相似文献
6.
Mahmoud Al‐Ktaifani Mwaffak Rukiah 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(9):o479-o483
Two different forms of meso‐3,3′‐[2,2‐dimethylpropane‐1,3‐diylbis(azanediyl)]dibutan‐2‐one dioxime, commonly called meso‐hexamethyl propylene amine oxime (HMPAO), C13H28N4O2, designated α and β, were isolated by fractional crystallization and their crystal structures were determined by powder X‐ray diffraction using the direct‐space method with the parallel tempering algorithm. The α form was first crystallized from acetonitrile solution, while the β form was obtained by recrystallization of the α phase from diethyl ether. The α form crystallizes in the triclinic system (space group P), with one molecule in the asymmetric unit, while the crystal of the β form is monoclinic (space group P21/n), with one molecule in the asymmetric unit. In both phases, the molecules have similar conformations and RS/EE geometric isomerism. The crystal packing of the two phases is dominated by intermolecular hydrogen‐bonding interactions between the two O—H oxime groups of an individual molecule and the amine N atoms of two different adjacent molecules, which lead to segregation of extended poly(meso‐HMPAO) one‐dimensional chains along the c direction. The structures of the two phases are primarily different due to the different orientations of the molecules in the chains. 相似文献
7.
Paul Tongwa Tiffany L. Kinnibrugh Geetha R. Kicchaiahgari Victor N. Khrustalev Tatiana V. Timofeeva 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(4):o155-o159
The molecules of the title compounds, C16H15NOS2, (I), and C16H13Br2NOS2, (II), are E,E‐isomers and consist of an extensive conjugated system, which determines their molecular geometries. Compound (I) crystallizes in the monoclinic space group P21/c. It has one thiophene ring disordered over two positions, with a minor component contribution of 0.100 (3). Compound (II) crystallizes in the noncentrosymmetric orthorhombic space group Pca21 with two independent molecules in the unit cell. These molecules are related by a noncrystallographic pseudo‐inversion center and possess very similar geometries. The crystal packings of (I) and (II) have a topologically common structural motif, viz. stacks along the b axis, in which the molecules are bound by weak C—H...O hydrogen bonds. The noncentrosymmetric packing of (II) is governed by attractive intermolecular Br...Br and Br...N interactions, which are also responsible for the very high density of (II) (1.861 Mg m−3). 相似文献
8.
Jos Alberto Galicia Aguilar Sylvain Berns 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(4):o176-o178
3,6‐Dinitrodurene (1,2,4,5‐tetramethyl‐3,6‐dinitrobenzene), C10H12N2O4, has been crystallized in two polymorphic forms which may be distinguished by their colours in the solid state. Polymorph I gives clear colourless prismatic crystals, while polymorph II crystallizes in the dark and under an inert atmosphere as irregular purple blocks. Both forms belong to the space group C2/c, with both asymmetric units containing two half‐molecules. One molecule is located on an inversion centre and the other lies on a twofold axis. The polymorphism arises from different orientations of the twofold axis: in form I, this axis passes through the mid‐points of two C—C bonds of the benzene ring and, as a consequence, all atoms in the asymmetric unit are in general positions. In form II, the N atoms of the nitro groups and the Cipso atoms are located on the binary axis. Comparing phases I and II, slightly different conformations are observed for the nitro substituents, while the stacking structures are very similar. 相似文献
9.
A. Subbiah Pandi D. Velmurugan S. Shanmuga Sundara Raj Hoong‐Kun Fun P. R. Seshadri D. Thirumalai 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):821-824
10‐(4‐Fluorophenyl)‐3,3,6,6,9‐pentamethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione, C24H28FNO2, (I), crystallizes with two crystallographically independent molecules (which differ slightly in conformation), while 10‐(4‐fluorophenyl)‐9‐propyl‐3,3,6,6‐tetramethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione, C26H32FNO2, (II), crystallizes with one molecule per asymmetric unit. In both structures, the central ring in the acridine moiety is in a sofa conformation, while the outer rings adopt intermediate half‐chair/sofa conformations. The central pyridine ring is orthogonal to the substituted phenyl ring. In both structures, the packing of the crystal is stabilized by C—H?O intermolecular hydrogen bonds. 相似文献
10.
Badiadka Narayana Hemmige S. Yathirajan Ravindranath S. Rathore Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(9):664-669
4‐Antipyrine [4‐amino‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one] and its derivatives exhibit a range of biological activities, including analgesic, antibacterial and anti‐inflammatory, and new examples are always of potential interest and value. 2‐(4‐Chlorophenyl)‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamide, C19H18ClN3O2, (I), crystallizes with Z′ = 2 in the space group P, whereas its positional isomer 2‐(2‐chlorophenyl)‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamide, (II), crystallizes with Z′ = 1 in the space group C2/c; the molecules of (II) are disordered over two sets of atomic sites having occupancies of 0.6020 (18) and 0.3980 (18). The two independent molecules of (I) adopt different molecular conformations, as do the two disorder components in (II), where the 2‐chlorophenyl substituents adopt different orientations. The molecules of (I) are linked by a combination of N—H…O and C—H…O hydrogen bonds to form centrosymmetric four‐molecule aggregates, while those of (II) are linked by the same types of hydrogen bonds forming sheets. The related compound N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)‐2‐(3‐methoxyphenyl)acetamide, C20H21N3O3, (III), is isomorphous with (I) but not strictly isostructural; again the two independent molecules adopt different molecular conformations, and the molecules are linked by N—H…O and C—H…O hydrogen bonds to form ribbons. Comparisons are made with some related structures, indicating that a hydrogen‐bonded R22(10) ring is the common structural motif. 相似文献
11.
Galal H. Elgemeie Shahinaz H. Sayed Peter G. Jones 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(1):90-92
The title compound, C10H11N3O3S, (I), crystallizes as the NH tautomer. The two rings subtend an interplanar angle of 72.54 (4)°. An intramolecular hydrogen bond is formed from the NH2 group to a sulfonyl O atom. The molecular packing involves layers of molecules parallel to the bc plane at x≃ 0, 1 etc., with two classical linear hydrogen bonds (amino–sulfonyl and pyrazoline–carbonyl N—H...O) and a further interaction (amino–sulfonyl N—H...O) completing a three‐centre system with the intramolecular contact. The analogous phenyl derivative, (II) [Elgemeie, Hanfy, Hopf & Jones (1998). Acta Cryst. C 54 , 136–138], crystallizes with essentially the same unit cell and packing pattern, but with two independent molecules that differ significantly in the orientation of the phenyl groups. The space group is P21/c for (I) but P21 for (II), which is thus a pseudosymmetric counterpart of (I). 相似文献
12.
Svitlana V. Shishkina Igor V. Ukrainets Olga V. Vashchenko Natali I. Voloshchuk Pavlo S. Bondarenko Lidiya A. Petrushova Galina Sim 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(1):69-74
The title benzothiazine‐3‐carboxamide, C17H16N2O4S, crystallized in two enantiomorphic crystal forms with the space groups P32 and P31 despite the absence of a classic stereogenic atom. The molecular structures are mirror images of each other. Only one sulfonyl O atom takes part in intramolecular hydrogen bonding as a proton acceptor and this atom is different in the two enantiomorphic structures. As a result, the S atom becomes a pseudo‐stereogenic centre. This fact is worth taking into account due to the different biological activities of the enantiomorphic forms. One form possesses a high analgesic activity, while the other form revealed a high anti‐inflammatory activity. 相似文献
13.
Wenhui Zhang Allen G. Oliver Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(10):o496-o498
4‐Deoxy‐4‐fluoro‐β‐d ‐glucopyranose, C6H11FO5, (I), crystallizes from water at room temperature in a slightly distorted 4C1 chair conformation. The observed chair distortion differs from that observed in β‐d ‐glucopyranose [Kouwijzer, van Eijck, Kooijman & Kroon (1995). Acta Cryst. B 51 , 209–220], (II), with the former skewed toward a BC3,O5 (boat) conformer and the latter toward an O5TBC2 (twist–boat) conformer, based on Cremer–Pople analysis. The exocyclic hydroxymethyl group conformations in (I) and (II) are similar; in both cases, the O—C—C—O torsion angle is ∼−60° (gg conformer). Intermolecular hydrogen bonding in the crystal structures of (I) and (II) is conserved in that identical patterns of donors and acceptors are observed for the exocyclic substituents and the ring O atom of each monosaccharide. Inspection of the crystal packing structures of (I) and (II) reveals an essentially identical packing configuration. 相似文献
14.
Hadgu Girmay Gebreslasie
yvind Jacobsen Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(8):o283-o287
The title compound (systematic name: methyl 2‐{2‐[(tert‐butoxycarbonyl)amino]‐2‐methylpropanamido}‐2‐methylpropanoate), C14H26N2O5, (I), crystallizes in the monoclinic space group P21/n in two polymorphic forms, each with one molecule in the asymmetric unit. The molecular conformation is essentially the same in both polymorphs, with the α‐aminoisobutyric acid (Aib) residues adopting ϕ and ψ values characteristic of α‐helical and mixed 310‐ and α‐helical conformations. The helical handedness of the C‐terminal residue (Aib2) is opposite to that of the N‐terminal residue (Aib1). In contrast to (I), the closely related peptide Boc‐Aib‐Aib‐OBn (Boc is tert‐butoxycarbonyl and Bn is benzyl) adopts an αL‐PII backbone conformation (or the mirror image conformation). Compound (I) forms hydrogen‐bonded parallel β‐sheet‐like tapes, with the carbonyl groups of Aib1 and Aib2 acting as hydrogen‐bond acceptors. This seems to represent an unusual packing for a protected dipeptide containing at least one α,α‐disubstituted residue. 相似文献
15.
S. Thinagar D. Velmurugan S. Shanmuga Sundara Raj Hoong‐Kun Fun S. C. Gupta H. Merazig S. Bouacida 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(4):o181-o183
The title compound 3,3′‐[o‐phenylenebis(methyleneoxy)]bis(6‐chloroflavone), C38H24Cl2O6, (I), crystallizes in the monoclinic space group C2/c, with the molecules lying across twofold rotation axes so that there is half a molecule in the asymmetric unit, while the other title compound, 3,3′‐propylenedioxybis[6‐chloro‐2‐(2‐furyl)‐4H‐1‐benzopyran‐4‐one], C29H18Cl2O8, (II), crystallizes in monoclinic space group P21/n with one molecule in the asymmetric unit. In both compounds, the benzopyran moiety is nearly planar, with dihedral angles between the two fused rings of 1.43 (8)° in (I), and 2.54 (7) and 3.00 (6)° with respect to the benzopyran moieties in the two halves of (II). The furan rings are twisted by 8.3 (1) and 8.4 (1)° in the two halves of (II). In both compounds, the molecular structure is stabilized by intramolecular C—H⃛O hydrogen bonds, while the crystal packing is stabilized by C—H⃛Cl and C—H⃛O intermolecular hydrogen bonds in (I) and (II), respectively. 相似文献
16.
Shuichao Dong Yaqiu Tao Xiaodong Shen Zhigang Pan 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(8):896-900
A new polymorph of bis(2‐aminopyridinium) fumarate–fumaric acid (1/1), 2C5H7N2+·C4H2O42−·C4H4O4, was obtained and its crystal structure determined by powder X‐ray diffraction. The new polymorph (form II) crystallizes in the triclinic system (space group P), while the previous reported polymorph [form I; Ballabh, Trivedi, Dastidar & Suresh (2002). CrystEngComm, 4 , 135–142; Büyükgüngör, Odabaşoğlu, Albayrak & Lönnecke (2004). Acta Cryst. C 60 , o470–o472] is monoclinic (space group P21/c). In both forms I and II, the asymmetric unit consists of one 2‐aminopyridinium cation, half a fumaric acid molecule and half a fumarate dianion. The fumarate dianion is involved in hydrogen bonding with two neighbouring 2‐aminopyridinium cations to form a hydrogen‐bonded trimer in both forms. In form II, the hydrogen‐bonded trimers are interlinked across centres of inversion via pairs of N—H...O hydrogen bonds, whereas such trimers are joined via single N—H...O hydrogen bonds in form I, leading to different packing modes for forms I and II. The results demonstrate the relevance and application of the powder diffraction method in the study of polymorphism of organic molecular materials. 相似文献
17.
Oleg Ya. Borbulevych Igor R. Golding Alexander N. Shchegolikhin Zinaida S. Klemenkova Mikhail Yu. Antipin 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(8):996-998
Although the two polymorphic modifications, (I) and (II), of the title compound, C13H10N2O, crystallize in the same space group (P21/c), their asymmetric units have Z′ values of 1 and 2, respectively. These are conformational polymorphs, since the molecules in phases (I) and (II) adopt different rotations of the phenyl ring with respect the central 2‐cyanocarboxyaminoprop‐2‐enyl fragment. Calculations of crystal packing using Cerius2 [Molecular Simulations (1999). 9685 Scranton Road, San Diego, CA 92121, USA] have shown that (I) is more stable than (II), by 1.3 kcal mol?1 for the crystallographically determined structures and by 1.56 kcal mol?1 for the optimized structures (1 kcal mol?1 = 4.184 kJ mol?1). This difference is mainly attributed to the different strengths of the hydrogen bonding in the two forms. 相似文献
18.
Mwaffak Rukiah Mahmoud Al‐Ktaifani 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(5):o166-o170
The structures of the title compounds, C9H8O3S, (I), and C13H11NO5S, (II), were determined by X‐ray powder diffraction. Both were solved using the direct‐space parallel tempering algorithm and refined using the Rietveld method. In (I), the C—S—C bond angle is slightly smaller than normal, indicating more p character in the bonding orbitals of the S atom. The carboxylic acid group joins across an inversion centre to form a dimer. The crystal packing includes a weak C—H...O hydrogen bond between an aromatic C—H group and a carboxylic acid O atom to form a two‐dimensional network parallel to (10). The C—S—C bond angle in (II) is larger than its counterpart in (I), indicating that the S atom of (II) has less p character in its bonding orbitals than that of (I), according to Bent's rule. The crystal structure of (II) includes weak C—H...O hydrogen bonds between the H atoms of the methylene groups and carbonyl O atoms, forming a three‐dimensional network. 相似文献
19.
Kenny Stahl Jette Oddershede Herbert Preikschat Erik Fischer Jacob S. Bennekou 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(3):m112-m115
The crystal structures of the title compounds, ammonium risedronate dihydrate, NH4+·C7H10NO7P2−·2H2O, (I), and potassium risedronate dihydrate, K+·C7H10NO7P2−·2H2O, (II), have been determined from single‐crystal X‐ray data collected at 120 K. Compound (I) forms a three‐dimensional hydrogen‐bonded network which connects the ammonium and risedronate ions and the water molecules. In compound (II), the K+ ions are seven‐coordinated in a capped distorted trigonal prism. The coordination polyhedra form chains by corner‐sharing, and these chains are connected by phosphonate groups into layers in the ac plane. The layers are stacked and connected by hydrogen bonds in the b direction. The risedronate conformation is determined by intramolecular interactions fine‐tuned by crystal packing effects. All H‐atom donors in both structures are involved in hydrogen bonding, with D⋯A distances between 2.510 (2) and 3.009 (2) Å. 相似文献
20.
Julio Gutierrez Rodney Eisenberg Gabrielle Herrensmith Thomas Tobin Tonglei Li Sihui Long 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(12):o593-o595
Details of the structures of two conformational polymorphs of the title compound, C12H17N2OS+·Cl−, are reported. In form (I) (space group P), the two N—H groups of the cation are in a trans conformation, while in form (II) (space group P21/c), they are in a cis arrangement. This results in different packing and hydrogen‐bond arrangements in the two forms, both of which have extended chains lying along the a direction. In form (I), these chains are composed of centrosymmetric R42(18) (N—H...Cl and O—H...Cl) hydrogen‐bonded rings and R22(18) (N—H...O) hydrogen‐bonded rings. In form (II), the chains are formed by centrosymmetric R42(18) (N—H...Cl and O—H...Cl) hydrogen‐bonded rings and by R42(12) (N—H...Cl) hydrogen‐bonded rings. 相似文献