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1.
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
2.
Alexander D. Roshal Artur Sikorski Vyacheslav N. Baumer Alexander I. Novikov Jerzy Baejowski 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):o626-o630
Crystallization (from ethyl acetate solution) of 2‐(4‐chlorophenyl)‐4‐methylchromenium perchlorate, C16H12ClO+·;ClO4−, (I), yields two monoclinic polymorphs with the space groups P21/n [polymorph (Ia)] and P21/c [polymorph (Ib)]; in both cases, Z = 4. Cations and anions, disordered in polymorph (Ib), form ion pairs in both polymorphs as a result of Cl—O...π interactions. Related by a centre of symmetry, neighbouring ion pairs in polymorph (Ia) are linked viaπ–π interactions between cationic fragments, and the resulting dimers are linked through a network of C—H...O(perchlorate) interactions between adjacent cations and anions. The ion pairs in polymorph (Ib), arranged in pairs of columns along the a axis, are linked through a network of C—H...O(perchlorate), C—Cl...π, π–π and C—Cl...O(perchlorate) interactions. The aromatic skeletons in polymorph (Ia) are parallel in the cationic fragments involved in dimers, but nonparallel in adjacent ion pairs not constituting dimers. In polymorph (Ib), these skeletons are parallel in pairs of columns, but nonparallel in adjacent pairs of columns; this is visible as a herring‐bone pattern. Differences in the crystal structures of the polymorphs are most probably the cause of their different colours. 相似文献
3.
Katharine F. Bowes Christopher Glidewell John N. Low Manuel Melguizo Antonio Quesada 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(1):o4-o8
Crystallization of 2‐amino‐4‐chloro‐6‐morpholinopyrimidine, C8H11ClN4O, (I), yields two polymorphs, both with space group P21/c, having Z′ = 1 (from diethyl ether solution) and Z′ = 2 (from dichloromethane solution), denoted (Ia) and (Ib), respectively. In polymorph (Ia), the molecules are linked by an N—H⋯O and an N—H⋯N hydrogen bond into sheets built from alternating R(8) and R(40) rings. In polymorph (Ib), one molecule acts as a triple acceptor of hydrogen bonds and the other acts as a single acceptor; one N—H⋯O and three N—H⋯N hydrogen bonds link the molecules in a complex chain containing two types of R(8) and one type of R(18) ring. 2‐Amino‐4‐chloro‐6‐piperidinopyrimidine, C9H13ClN4, (II), which is isomorphous with polymorph (Ib), also has Z′ = 2 in P21/c, and the molecules are linked by three N—H⋯N hydrogen bonds into a centrosymmetric four‐molecule aggregate containing three R(8) rings. 相似文献
4.
Vladimir N. Nesterov Volodymyr V. Nesterov 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):o781-o785
Two new polymorph forms, (Ia) and (Ib), of the title compound, C14H17N3S, and its solvate with acetonitrile, C14H17N3S·0.25C2H3N, (Ic), have been investigated. Crystals of the two polymorphs were grown from different solvents, viz. ethanol and N,N‐dimethylformamide, respectively. The polymorphs have different orientations of the thioamide group relative to the CN substituent, with s‐cis and s‐trans geometry of the C=C—C=S diene fragment, respectively. Compound (Ic) contains two independent molecules, A and B, with s‐cis geometry, and the solvate molecule lies on a twofold axis. The core of each molecule is slightly non‐planar; the dihedral angles between the conjugated C=C—CN linkage and the phenyl ring, and between this linkage and the thioamide group are 13.4 (2) and 12.0 (2)° in (Ia), 14.0 (2) and 18.2 (2)° in (Ib), 2.3 (3) and 12.7 (4)° in molecule A of (Ic), and 23.2 (3) and 8.1 (4)° in molecule B of (Ic). As a result of strong conjugation between donor and acceptor parts, the substituted phenyl rings have noticeable quinoid character. In (Ib), there exists a very strong intramolecular steric interaction (H⋯H = 1.95 Å) between the bridging and thioamide parts of the molecule, which makes such a form less stable. In the crystal structure of (Ia), intermolecular N—H⋯N and N—H⋯S hydrogen bonds link molecules into infinite tapes along the [10] direction. In (Ib), such intermolecular hydrogen bonds link molecules into infinite (101) planes. In (Ic), intermolecular N—H⋯N hydrogen bonds link molecules A and B into dimers, which are connected via N—H⋯S hydrogen bonds and form infinite chains along the c direction. 相似文献
5.
Erli Sugiono Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(2):o84-o86
Two polymorphs of the title compound, C16H16O3, have been obtained from the same solution. One polymorph, (Im), crystallizes in the monoclinic space group P21, while the other, (Io), crystallizes in the orthorhombic space group P212121. The cell constants of the two polymorphs are surprisingly similar. Whereas the a and b axes are equal in the two structures, the c axis in (Io) is twice as long as that in (Im). The monoclinic angle β is 95.084 (9)° compared with 90° in the orthorhombic crystal system. The cell volume of (Im) is almost exactly half of the cell volume of (Io). The packing motifs are also very similar in the two structures. However, whereas the molecules in (Im) are related by a twofold screw axis just in the direction of the b axis, in (Io) there are twofold screw axes along all three directions of the unit cell. 相似文献
6.
Peter G. Jones Henning Hopf Anamaria Silaghi Christian Nther 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(10):o405-o408
The title compound, C8H4Br6, (I), initially crystallized from deuterochloroform as the comcomitant polymorphs (Ia) (prisms, space group P21/n, Z = 2) and (Ib) (hexagonal plates, space group C2/c, Z = 4). The molecules in both forms display crystallographic inversion symmetry. All further attempts to crystallize the compound led exclusively to (Ib), so that (Ia) may be regarded as a `disappearing polymorph'. Surprisingly, however, the density of (Ia) is greater than that of (Ib). The only significant difference between the molecular structures is the orientation of the CBr3 groups. The molecular packing of both structures is largely determined by Br...Br interactions, although (Ia) also displays a C—H...Br hydrogen bond and both polymorphs display one Br...π contact. For (Ia), six of the eight contacts combine to form a tube‐like substructure parallel to the a axis. For (Ib), the two shortest Br...Br contacts link `half' molecules consisting of C—CBr3 groups to form double layers parallel to (001) in the regions z≃, . 相似文献
7.
Madeleine Helliwell Salma Moosun Minu G. Bhowon Sabina Jhaumeer‐Laulloo John A. Joule 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(10):o387-o391
The structures of N,N′‐bis(2‐methylphenyl)‐2,2′‐thiodibenzamide, C28H24N2O2S, (Ia), N,N′‐bis(2‐ethylphenyl)‐2,2′‐thiodibenzamide, C30H28N2O2S, (Ib), and N,N′‐bis(2‐bromophenyl)‐2,2′‐thiodibenzamide, C26H18Br2N2O2S, (Ic), are compared with each other. For the 19 atoms of the consistent thiodibenzamide core, the r.m.s. deviations of the molecules in pairs are 0.29, 0.90 and 0.80 Å for (Ia)/(Ib), (Ia)/(Ic) and (Ib)/(Ic), respectively. The conformations of the central parts of molecules (Ia) and (Ib) are similar due to an intramolecular N—H...O hydrogen‐bonding interaction. The molecules of (Ia) are further linked into infinite chains along the c axis by intermolecular N—H...O interactions, whereas the molecules of (Ib) are linked into chains along b by an intermolecular N—H...π contact. The conformation of (Ic) is quite different from those of (Ia) and (Ib), since there is no intramolecular N—H...O hydrogen bond, but instead there is a possible intramolecular N—H...Br hydrogen bond. The molecules are linked into chains along c by intermolecular N—H...O hydrogen bonds. 相似文献
8.
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
9.
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
10.
Jeong‐Myeong Ha Victor Young 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(8):o388-o395
Four crystal structure determinations of 2,2,3,3,4,4‐hexafluoropentane‐1,5‐diol (HFPD), C5H6F6O2, were conducted on a single specimen by varying the temperature. Two polymorphs of HFPD were found to be enantiotropically related as phases (I) and (II), both in the space group P1. These structures contain closely related R44(20) sheets. A structure determination was completed on form (Ia) at 283 K. Form (Ia) was then supercooled below the phase transition temperature at 279 to 173 K to give form (Ib) for a second structure determination. Metastable form (Ib) was transformed by momentary warming and recooling to give form (II) for a third structure determination at 173 K. Form (II) transformed to form (Ic) upon warming to 283 K. Enantiotropic phase transitions between phases (I) and (II) were confirmed with X‐ray powder diffraction and differential scanning calorimetry. Form (Ia) was found as a twin by nonmerohedry by a reflection in (011). This twinning persists in all phases described. Additional twinning was found after the phase (I) to phase (II) transformation. These two additional twin components are related to the first pair by a 180° rotation about the (012) plane. This latter pair of twins persisted as the specimen was warmed back to form (Ic) at 283 K. 相似文献
11.
Gholamhossein Mohammadnezhad Mostafa M. Amini Vratislav Langer 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(2):m44-m47
Two distinct polymorphs of bis(μ2‐methylquinolin‐8‐olato)‐κ3N,O:O;κ3O:N,O‐bis[(isothiocyanato‐κN)lead(II)], [Pb2(C10H8NO)2(NCS)2], (I), forming dinuclear complexes from a methanolic solution containing lead(II) nitrate, 2‐methylquinolin‐8‐ol (M‐Hq) and KSCN, crystallized concomitantly as colourless prisms [form (Ia)] and long thin colourless needles [form (Ib)]. In both cases, the complexes lie across a centre of inversion. The polymorphs differ substantially in their conformation and in their interactions, viz. Pb...S and π–π for form (Ia) and Pb...S, Pb...π and C—H...π for form (Ib). 相似文献
12.
Rachael Clarke Kay Latham Colin Rix Jonathan White 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(1):m7-m9
The title complex, [Cu(C12H8N2)2]I, (I), has been crystallized in two polymorphic forms, both containing four‐coordinate copper. Both forms are orthorhombic, with form (Ia) crystallizing in the primitive space group Pban and form (Ib) in the c‐centred space group Ccca. In (Ia), the complex cation and the I− anion both have 222 crystallographic symmetry, and in (Ib), the complex cation has approximate 222 symmetry, with the I− counter‐ion distributed over three special positions. 相似文献
13.
Jerzy Cieplik Janusz Pluta Tadeusz Lis Iwona Bryndal 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):o259-o261
Two polymorphic forms of the title compound, C24H20Cl2N4, were obtained and characterized using X‐ray crystal structure analysis. Colourless crystals of polymorph (Ia) were obtained from the oily mother residue. Recrystallization of polymorph (Ia) from an acetone–methanol mixture resulted in pale‐yellow crystals of polymorph (Ib). The major feature distinguishing the two polymorphic forms is their interaction modes, and hence their packing arrangements. In the crystal structure of polymorph (Ia), there are N—H⋯N hydrogen bonds and also aromatic π–π stacking interactions between molecules. The molecules of polymorph (Ib) are linked by N—H⋯Cl hydrogen bonds only. 相似文献
14.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(6):696-702
A concise and efficient synthesis of 6‐benzimidazolyl‐5‐nitrosopyrimidines has been developed using Schiff base‐type intermediates derived from N4‐(2‐aminophenyl)‐6‐methoxy‐5‐nitrosopyrimidine‐2,4‐diamine. 6‐Methoxy‐N4‐{2‐[(4‐methylbenzylidene)amino]phenyl}‐5‐nitrosopyrimidine‐2,4‐diamine, (I), and N4‐{2‐[(ethoxymethylidene)amino]phenyl}‐6‐methoxy‐5‐nitrosopyrimidine‐2,4‐diamine, (III), both crystallize from dimethyl sulfoxide solution as the 1:1 solvates C19H18N6O2·C2H6OS, (Ia), and C14H16N6O3·C2H6OS, (IIIa), respectively. The interatomic distances in these intermediates indicate significant electronic polarization within the substituted pyrimidine system. In each of (Ia) and (IIIa), intermolecular N—H…O hydrogen bonds generate centrosymmetric four‐molecule aggregates. Oxidative ring closure of intermediate (I), effected using ammonium hexanitratocerate(IV), produced 4‐methoxy‐6‐[2‐(4‐methylphenyl‐1H‐benzimidazol‐1‐yl]‐5‐nitrosopyrimidin‐2‐amine, C19H16N6O2, (II) [Cobo et al. (2018). Private communication (CCDC 1830889). CCDC, Cambridge, England], where the extent of electronic polarization is much less than in (Ia) and (IIIa). A combination of N—H…N and C—H…O hydrogen bonds links the molecules of (II) into complex sheets. 相似文献
15.
Sean R. Parkin Edward J. Behrman 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(8):o324-o328
Crystals of 5‐hydroxy‐6‐methyl‐2‐pyridone, (I), grown from a variety of solvents, are invariably trigonal (space group R); these are 5‐hydroxy‐6‐methyl‐2‐pyridone acetone 0.1667‐solvate, C6H7NO2·0.1667C3H6O, (Ia), and 6‐methyl‐5‐hydroxy‐2‐pyridone propan‐2‐ol 0.1667‐solvate, C6H7NO2·0.1667C3H8O, (Ib), and the forms from methanol, (Ic), water, (Id), benzonitrile, (Ie), and benzyl alcohol, (If). They incorporate channels running the length of the c axis that contain extensively disordered solvent molecules. A solvent‐free sublimed powder of 5‐hydroxy‐6‐methyl‐2‐pyridone microcrystals is essentially isostructural. Inversion‐related host molecules interact via pairs of N—H...O hydrogen bonds to form R22(8) dimers. Six of these dimers form large R126(42) puckered rings, in which the O atom of each N—H...O hydrogen bond is also the acceptor in an O—H...O hydrogen bond that involves the 5‐hydroxy group. The large R126(42) rings straddle the axes and form stacked columns viaπ–π interactions between inversion‐related molecules of (I) [mean interplanar spacing = 3.254 Å and ring centroid–centroid distance = 3.688 (2) Å]. The channels are lined by methyl groups, which all point inwards to the centre of the channels. 相似文献
16.
Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):772-774
The title compound, C26H23NO2, (Ia) and (Ib), shows polymorphism with crystals obtained from different solvents displaying different crystal structures. However, it is not the geometry of the single molecules nor the hydrogen‐bond pattern that is different in (Ia) and (Ib), but the way in which the hydrogen‐bonded chains, running along the a‐axis direction, are arranged with respect to each other. 相似文献
17.
Kritof Kranjc Marijan Ko
evar Franc Perdih 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(6):o201-o205
Methyl 2‐benzamido‐4‐(3,4‐dimethoxyphenyl)‐5‐methylbenzoate, C24H23NO5, (Ia), and N‐{5‐benzoyl‐2‐[(Z)‐2‐methoxyethenyl]‐4‐methylphenyl}benzamide, C24H21NO3, (IIa), were formed via a Diels–Alder reaction of appropriately substituted 2H‐pyran‐2‐ones and methyl propiolate or (Z)‐1‐methoxybut‐1‐en‐3‐yne, respectively. Each of these cycloadditions might yield two different regioisomers, but just one was obtained in each case. In (Ia), an intramolecular N—H...O hydrogen bond closes a six‐membered ring. A chain is formed due to aromatic π–π interactions, and a three‐dimensional framework structure is formed by a combination of C—H...O and C—H...π(arene) hydrogen bonds. Compound (IIa) was formed not only regioselectively but also chemoselectively, with just the triple bond reacting and the double bond remaining unchanged. Compound (IIa) crystallizes as N—H...O hydrogen‐bonded dimers stabilized by aromatic π–π interactions. Dimers of (IIa) are connected into a chain by weak C—H...π(arene) interactions. 相似文献
18.
Ewa Matczak‐Jon Katarzyna
lepokura 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(11):o450-o456
In the crystal structures of the conformational isomers hydrogen {phosphono[(pyridin‐1‐ium‐3‐yl)amino]methyl}phosphonate monohydrate (pro‐E), C6H10N2O6P2·H2O, (Ia), and hydrogen {phosphono[(pyridin‐1‐ium‐3‐yl)amino]methyl}phosphonate (pro‐Z), C6H10N2O6P2, (Ib), the related hydrogen {[(2‐chloropyridin‐1‐ium‐3‐yl)amino](phosphono)methyl}phosphonate (pro‐E), C6H9ClN2O6P2, (II), and the salt bis(6‐chloropyridin‐3‐aminium) [hydrogen bis({[2‐chloropyridin‐1‐ium‐3‐yl(0.5+)]amino}methylenediphosphonate)] (pro‐Z), 2C5H6ClN2+·C12H16Cl2N4O12P42−, (III), chain–chain interactions involving phosphono (–PO3H2) and phosphonate (–PO3H−) groups are dominant in determining the crystal packing. The crystals of (Ia) and (III) comprise similar ribbons, which are held together by N—H...O interactions, by water‐ or cation‐mediated contacts, and by π–π interactions between the aromatic rings of adjacent zwitterions in (Ia), and those of the cations and anions in (III). The crystals of (Ib) and (II) have a layered architecture: the former exhibits highly corrugated monolayers perpendicular to the [100] direction, while in the latter, flat bilayers parallel to the (001) plane are formed. In both (Ib) and (II), the interlayer contacts are realised through N—H...O hydrogen bonds and weak C—H...O interactions involving aromatic C atoms. 相似文献
19.
Xinjiang Huang Genevieve H. Kuhn Vladimir N. Nesterov Boris B. Averkiev Benjamin Penn Mikhail Yu. Antipin Tatiana V. Timofeeva 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):o624-o628
Syntheses and X‐ray structural investigations have been carried out for (E)‐(4‐hydroxyphenyl)(4‐nitrophenyl)diazene, C12H9N3O3, (Ia), (E)‐(4‐methoxyphenyl)(4‐nitrophenyl)diazene, C13H11N3O3, (IIIa), and (E)‐[4‐(6‐bromohexyloxy)phenyl](4‐cyanophenyl)diazene, C19H20BrN3O, (IIIc). In all of these compounds, the molecules are almost planar and the azobenzene core has a trans geometry. Compound (Ia) contains four and compound (IIIc) contains two independent molecules in the asymmetric unit, both in space group P (No. 2). In compound (Ia), the independent molecules are almost identical, whereas in crystal (IIIc), the two independent molecules differ significantly due to different conformations of the alkyl tails. In the crystals of (Ia) and (IIIa), the molecules are arranged in almost planar sheets. In the crystal of (IIIc), the molecules are packed with a marked separation of the azobenzene cores and alkyl tails, which is common for the solid crystalline precursors of mesogens. 相似文献
20.
Chin‐Ping Yang Ruei‐Shin Chen 《Journal of polymer science. Part A, Polymer chemistry》2000,38(11):2082-2090
1,1‐Bis[4‐(4‐aminophenoxy)phenyl]‐1‐phenylethane (BAPPE) was prepared through nucleophilic substitution reaction of 1,1‐bis(4‐hydroxyphenyl)‐1‐phenylethane and p‐chloronitrobenzene in the presence of K2CO3 in N,N‐dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C. Novel organosoluble polyimides and copolyimides were synthesized from BAPPE and six kinds of commercial dianhydrides, including pyromellitic dianhydride (PMDA, Ia ), 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA, Ib ), 3,3′,4,4′‐ biphenyltetracarboxylic dianhydride (BPDA, Ic ), 4,4′‐oxydiphthalic anhydride (ODPA, Id ), 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA, Ie ) and 4,4′‐hexafluoroisopropylidenediphthalic anhydride (6FDA, If ). Differing with the conventional polyimide process by thermal cyclodehydration of poly(amic acid), when polyimides were prepared by chemical cyclodehydration with N‐methyl‐2‐pyrrolidone as used solvent, resulted polymers showed good solubility. Additional, Ia,b were mixed respectively with the rest of dianhydrides (Ic–f) and BAPPE at certain molar ratios to prepare copolyimides with arbitrary solubilities. These polyimides and copolyimides were characterized by good mechanical properties together with good thermal stability. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2082–2090, 2000 相似文献