Two polymorphs of bis(2‐carbamoylguanidinium) fluorophosphonate dihydrate

Two polymorphs of bis(2‐carbamoylguanidinium) fluorophosphonate dihydrate, 2C₂H₇N₄O⁺·FO₃P²⁻·2H₂O, are presented. Polymorph (I), crystallizing in the space group Pnma, is slightly less densely packed than polymorph (II), which crystallizes in Pbca. In (I), the fluorophosphonate anion is situated on a crystallographic mirror plane and the O atom of the water molecule is disordered over two positions, in contrast with its H atoms. The hydrogen‐bond patterns in both polymorphs share similar features. There are O—H...O and N—H...O hydrogen bonds in both structures. The water molecules donate their H atoms to the O atoms of the fluorophosphonates exclusively. The water molecules and the fluorophosphonates participate in the formation of R⁴₄(10) graph‐set motifs. These motifs extend along the a axis in each structure. The water molecules are also acceptors of either one [in (I) and (II)] or two [in (II)] N—H...O hydrogen bonds. The water molecules are significant building elements in the formation of a three‐dimensional hydrogen‐bond network in both structures. Despite these similarities, there are substantial differences between the hydrogen‐bond networks of (I) and (II). The N—H...O and O—H...O hydrogen bonds in (I) are stronger and weaker, respectively, than those in (II). Moreover, in (I), the shortest N—H...O hydrogen bonds are shorter than the shortest O—H...O hydrogen bonds, which is an unusual feature. The properties of the hydrogen‐bond network in (II) can be related to an unusually long P—O bond length for an unhydrogenated fluorophosphonate anion that is present in this structure. In both structures, the N—H...F interactions are far weaker than the N—H...O hydrogen bonds. It follows from the structure analysis that (II) seems to be thermodynamically more stable than (I).     

Synthesis of poly(p‐phenylene sulfide) from bis(4‐bromophenyl) disulfide

Improved reaction conditions for the preparation of poly(p‐phenylene sulfide) (PPS) directly from bis(4‐bromophenyl) disulfide (BBD) have been established. Heating BBD with magnesium metal afforded only a low molecular weight polymer. PPS with a melting temperature around 280 °C was obtained from BBD in the presence of sodium carbonate or zinc metal. The best results were obtained with the addition of a catalytic amount of KI to the zinc–BBD mixture. Polymers prepared by the above methods are semicrystalline and dissolve in 1‐chloronaphthalene and have properties comparable to commercial PPS. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 900–904, 2006     

Two new polymorphs of di­phenyl(4‐pyridyl)­methyl methacryl­ate

The title compound (D4PyMA), C₂₂H₁₉NO₂, exhibits polymorphism after crystallization by slow evaporation from a binary mixture of chloro­form and hexane. Long needle‐like crystals have an orthorhombic structure (space group Fdd2), with one mol­ecule in the asymmetric unit, while small tablet‐like crystals exhibit a monoclinic crystal structure (space group P2₁/n), in which two independent but chemically identical mol­ecules comprise the asymmetric unit. The bond lengths and angles are normal, while the torsion angles around the –C—O– bond linking the di­phenyl(4‐pyridyl)methyl and methacryl­ate groups show the flexibility of the mol­ecule by way of packing effects. The two polymorphs both contain weak C—H⋯π and C—H⋯O/N contacts but have different conformations.     

Two polymorphs of bis(1,10‐phenanthroline‐κ2N,N′)copper(I) iodide

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.     

Concomitant polymorphs of 1,3‐bis(3‐fluorophenyl)urea

Hydrogen bonding between urea functionalities is a common structural motif employed in crystal‐engineering studies. Crystallization of 1,3‐bis(3‐fluorophenyl)urea, C₁₃H₁₀F₂N₂O, from many solvents yielded concomitant mixtures of at least two polymorphs. In the monoclinic form, one‐dimensional chains of hydrogen‐bonded urea molecules align in an antiparallel orientation, as is typical of many diphenylureas. In the orthorhombic form, one‐dimensional chains of hydrogen‐bonded urea molecules have a parallel orientation rarely observed in symmetrically substituted diphenylureas.     

Bis­[2‐(di­phenyl­phosphinoyl)­benzene] di­sulfide

The title compound, [2‐Ph₂P(O)C₆H₄S]₂ or C₃₆H₂₈O₂P₂S₂, obtained by electrochemical oxidation of 2‐(di­phenyl­phosphino)­benzene­thiol, has twofold crystallographic symmetry. Principal dimensions include S—S 2.0212 (15) Å, S—C 1.786 (3) Å and C—S—S—C 81.34 (14)°.     

Two new polymorphs of trans‐bis(hinokitiolato)copper(II)

The title complex [systematic name: trans‐bis(3‐iso­propyl‐7‐oxo­cyclo­hepta‐1,3,5‐trienolato)copper(II)], [Cu(C₁₀H₁₁O₂)₂],is a substance possessing antimicrobial activity. The compound crystallizes in a number of polymorphic forms, the structures for two of which are reported here. Stacks of square‐planar mol­ecules exhibiting weak intermolecular copper–olefin π interactions (not observed in earlier reports on this substance) are described. The mol­ecules have crystallographically imposed inversion symmetry, with stacking and copper–olefin π distances ranging from 3.226 (2) to 3.336 (1) Å.     

Two polymorphs of 2,5‐dichloro‐3,6‐bis(dibenzylamino)‐p‐hydroquinone with flexible dibenzylamino groups

We obtained two conformational polymorphs of 2,5‐dichloro‐3,6‐bis(dibenzylamino)‐p‐hydroquinone, C₃₄H₃₀Cl₂N₂O₂. Both polymorphs have an inversion centre at the centre of the hydroquinone ring (Z′ = ), and there are no significant differences between their bond lengths and angles. The most significant structural difference in the molecular conformations was found in the rotation of the phenyl rings of the two crystallographically independent benzyl groups. The crystal structures of the polymorphs were distinguishable with respect to the arrangement of the hydroquinone rings and the packing motif of the phenyl rings that form part of the benzyl groups. The phenyl groups of one polymorph are arranged in a face‐to‐edge motif between adjacent molecules, with intermolecular C—H…π interactions, whereas the phenyl rings in the other polymorph form a lamellar stacking pattern with no significant intermolecular interactions. We suggest that this partial conformational difference in the molecular structures leads to the significant structural differences observed in their molecular arrangements.     

Two polymorphs of (2‐carboxyethyl)(phenyl)phosphinic acid

Two polymorphs of (2‐carboxyethyl)(phenyl)phosphinic acid, C₉H₁₁O₄P, crystallize in the chiral P2₁2₁2₁ space group with similar unit‐cell parameters. They feature an essentially similar hydrogen‐bonding motif but differ slightly in their detailed geometric parameters. For both polymorphs, the unequivocal location of the hydroxy H atoms together with the expected differences in the P—O bond lengths establish unequivocally that both forms contain the S isomer; the protonated phosphinic acid and carboxy O atoms serve as hydrogen‐bond donors, while the second phosphinic acid O atom acts as a double hydrogen‐bond acceptor and the remaining carboxy O atom is not involved in hydrogen bonding. Thus, an undulating two‐dimensional supramolecular layer aggregate is formed based on an R₄³(20) ring unit. Such polymorphism derives from the rotation of the C—C single bonds between the two hydrogen‐bond‐involved carboxy and phosphinic acid moieties.     

Two concomitant polymorphs of N,N′‐bis[4‐(diethylamino)phenyl]terephthaldiamide

The title compound, C₂₈H₃₄N₄O₂, crystallizes simultaneously as a monoclinic, (Im), and a (twinned) triclinic polymorph, (It), from d₆‐dimethyl sulfoxide. Polymorph (It) (P, Z = 1) displays the standard `ladder' packing for this group of compounds, with neighbouring inversion‐symmetric molecules related by translation and connected by hydrogen bonds of the form N—H...O=C. Polymorph (Im) (Cc, Z = 4) has no imposed symmetry; there are three independent hydrogen bonds, one classical N—H...O=C and a bifurcated system with N—H...O=C augmented by a short C—H...O=C interaction. Each molecule is thereby linked to four neighbouring molecules, two lower and two higher, so that a crosslinked three‐dimensional pattern is formed rather than the standard ladder.     

A comparative study of two polymorphs of bis(1‐hydroxy‐2‐methylpropan‐2‐aminium) carbonate

Alkanolamines have been known for their high CO₂ absorption for over 60 years and are used widely in the natural gas industry for reversible CO₂ capture. In an attempt to crystallize a salt of (RS)‐2‐(3‐benzoylphenyl)propionic acid with 2‐amino‐2‐methylpropan‐1‐ol, we obtained instead a polymorph (denoted polymorph II) of bis(1‐hydroxy‐2‐methylpropan‐2‐aminium) carbonate, 2C₄H₁₂NO⁺·CO₃²⁻, (I), suggesting that the amine group of the former compound captured CO₂ from the atmosphere forming the aminium carbonate salt. This new polymorph was characterized by single‐crystal X‐ray diffraction analysis at low temperature (100 K). The salt crystallizes in the monoclinic system (space group C2/c, Z = 4), while a previously reported form of the same salt (denoted polymorph I) crystallizes in the triclinic system (space group P, Z = 2) [Barzagli et al. (2012). ChemSusChem, 5 , 1724–1731]. The asymmetric unit of polymorph II contains one 1‐hydroxy‐2‐methylpropan‐2‐aminium cation and half a carbonate anion, located on a twofold axis, while the asymmetric unit of polymorph I contains two cations and one anion. These polymorphs exhibit similar structural features in their three‐dimensional packing. Indeed, similar layers of an alternating cation–anion–cation neutral structure are observed in their molecular arrangements. Within each layer, carbonate anions and 1‐hydroxy‐2‐methylpropan‐2‐aminium cations form planes bound to each other through N—H…O and O—H…O hydrogen bonds. In both polymorphs, the layers are linked to each other via van der Waals interactions and C—H…O contacts. In polymorph II, a highly directional C—H…O contact (C—H…O = 156°) shows as a hydrogen‐bonding interaction. Periodic theoretical density functional theory (DFT) calculations indicate that both polymorphs present very similar stabilities.     

Two polymorphs of 2‐(4‐chlorophenyl)‐4‐methylchromenium perchlorate

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.     

1,3‐Propane­di­ammonium bis(3′‐nitro‐trans‐cinnamate) and trans‐1,2‐cyclo­hexane­di­ammonium bis(3′‐nitro‐trans‐cinnamate)

In the title two adducts, C₃H₁₂N₂²⁺·2C₉H₆NO₄^?, (I), and C₆H₁₆N₂²⁺·2C₉H₆NO₄^?, (II), hydrogen bonds between the di­ammonium and carboxyl­ate ions form a two‐dimensional network parallel to the ab plane in (I) and one‐dimensional chains along the c axis in (II). The cyclo­hexane­di­ammonium ion in (II) has a crystallographic twofold axis.     

cis‐Bis(3,6‐di­hydro‐2H‐1,2‐oxazine‐N)­di­iodo­platinum(II) and cis‐bis(3,4,5,6‐tetra­hydro‐2H‐1,2‐oxazine‐N)­di­iodo­platinum(II)

The title complexes, [Pt(C₄H₇NO)₂I₂], (I), and [Pt(C₄H₉NO)₂I₂], (II), possess similar square‐planar coordination geometries with modest distortions from ideality. For (I), the cis‐L—Pt—L angles are in the range 87.0 (4)–94.2 (3)°, while the trans angles are 174.4 (3) and 176.4 (3)°. For (II), cis‐L—Pt—L are 86.1 (8)–94.2 (6)° and trans‐L—Pt—L are 174.4 (6) and 177.4 (5)°. One 3,6‐di­hydro‐2H‐1,2‐oxazine ligand in (I) is rotated so that the N—O bond is out of the square plane by approximately 70°, while the N—C bond is only ca 20° out of the plane. The other oxazine ligand is rotated so that the N—C bond is about 80° out of the plane, while the N—O bond is out of the plane by approximately 24°. In (II), the 3,4,5,6‐tetra­hydro‐2H‐1,2‐oxazine ligands are also positioned with one having the N—O bond further out of the plane and the other having the N—C bond positioned in that fashion. Both ligands, however, are rotated approximately 90° compared with their positions in (I). In both complexes, this results in an unsymmetrical distortion of the I—Pt—N bond angles in which one is expanded and the other contracted. These features are compared to those of reported cis‐di­amine­di­iodo­platinum(II) complexes.     

2,3,6,7‐Tetra­hydroxy‐9,10‐di­methyl‐9,10‐di­hydro‐9,10‐ethano­anthracene bis(1,4‐dioxane) solvate

2,3,6,7‐Tetra­hydroxy‐9,10‐di­methyl‐9,10‐di­hydro‐9,10‐ethano­anthracene crystallizes with 1,4‐dioxane to give a bis‐solvate, C₁₈H₁₈O₄·2C₄H₈O₂. The bis­(catechol) mol­ecule is located on a twofold axis and the two aromatic rings form a dihedral angle of 130.61 (4)°. Hydro­gen bonds are formed between the hydroxyl groups and either a neighbouring bis­(catechol) mol­ecule or the ether‐O atom of a dioxane mol­ecule.     

Intramolecular cyclization of 4,7‐bis(2‐bromo­acetyl)‐1‐thia‐4,7‐di­azacyclo­nonane

The reaction of 1‐thia‐4,7‐di­azacyclo­nonane with bromo­acetyl bromide in CHCl₃ affords the unexpected salt 4‐(2‐bromo­acetyl)‐8‐oxo‐1‐thionia‐4,7‐di­aza­bi­cyclo­[5.2.2]­un­decane bromide, C₁₀H₁₆BrN₂O₂S⁺·Br⁻. Two units of the salt are linked by S⋯Br contacts about a crystallographic inversion centre, thus forming dimers that are linked by Br⋯Br contacts into extended ribbons. S⋯O contacts between these ribbons generate a two‐dimensional sheet.     

Two three‐dimensional networks in two polymorphs of biphenyl‐4,4′‐diaminium bis(3‐carboxy‐4‐hydroxybenzenesulfonate) dihydrate

Two polymorphs of biphenyl‐4,4′‐diaminium bis(3‐carboxy‐4‐hydroxybenzenesulfonate) dihydrate, C₁₂H₁₄N₂²⁺·2C₇H₅O₆S⁻·2H₂O, have been obtained and crystallographically characterized. Polymorph (I) crystallizes in the space group P2₁/c with Z′ = 2 and polymorph (II) in the space group P with Z′ = 0.5. The benzidinium cation in (II) is located on a crystallographic inversion centre. In both (I) and (II), the sulfonic acid H atoms are transferred to the benzidine N atoms, forming dihydrated 1:2 molecular adducts (base–acid). In the crystal packings of (I) and (II), the component ions are linked into three‐dimensional networks by combinations of X—H...O (X = O, N and C) hydrogen bonds. In addition, π–π interactions are observed in (I) between inversion‐related benzene rings [centroid–centroid distances = 3.632 (2) and 3.627 (2) Å]. In order to simplify the complex three‐dimensional networks in (I) and (II), we also give their rationalized topological analyses.     

Bis­[N,N‐bis(2‐hydroxy­ethyl)­di­thio­carbamato]­di­methyl­tin(IV)

The title compound, [Sn(CH₃)₂(C₅H₁₀NO₂S₂)₂], has crystallographic mirror symmetry (C—Sn—C on mirror plane) and the coordination polyhedron around the Sn atom is a tetrahedron [C—Sn—C 139.3 (2)° and S—Sn—S 82.3 (1)°] distorted towards a skew‐trapezoidal bipyramid owing to an intramolecular Sn?S contact [3.0427 (6) Å]. The mol­ecules are linked into a linear chain by intermolecular O—H?O hydrogen bonds [O?O 2.646 (3) Å].     

Two polymorphs of 20‐desmethyl‐β‐carotene

Two polymorphs of 20‐desmethyl‐β‐carotene (systematic name: 20‐nor‐β,β‐carotene), C₃₉H₅₄, in monoclinic and triclinic space groups, were formed in the same vial by recrystallization from pyridine and water. Each polymorph crystallizes with the complete molecule as the asymmetric unit, and the two polymorphs show differing patterns of disorder. The β end rings of both polymorphs have the 6‐s‐cis conformation, and are twisted out of the plane of the polyene chain by angles of −53.2 (8) and 47.3 (8)° for the monoclinic polymorph, and −43.6 (3) and 56.1 (3)° for the triclinic polymorph. The cyclohexene end groups are in the half‐chair conformation, but the triclinic polymorph shows disorder of one ring. Overlay of the molecules shows that they differ in the degree of nonplanarity of the polyene chains and the angles of twist of the end rings. The packing arrangements of the two polymorphs are quite different, with the monoclinic polymorph showing short intermolecular contacts of the disordered methyl groups with adjacent polyene chain atoms, and the triclinic polymorph showing π–π stacking interactions of the almost parallel polyene chains. The determination of the crystal structures of the two title polymorphs of 20‐desmethyl‐β‐carotene allows information to be gained regarding the structural effects on the polyene chain, as well as on the end groups, versus that of the parent compound β‐carotene. The absence of the methyl group is known to have an impact on various functions of the title compound.     

Di­chloro­bis(3,5‐di­methyl­pyrazole‐N2)methyl­phenyl­tin(IV)

The title compound, [SnCl₂(CH₃)(C₆H₅)(C₅H₈N₂)₂], was obtained by reaction of di­chloro­methyl­phenyl­tin(IV) and 3,5‐di­methyl­pyrazole (dmpz) in chloro­form, and was recrystallized from acetone. The structure consists of octahedral all‐trans [SnMePhCl₂(dmpz)₂] mol­ecules, with the Sn atom coordinated to two C [Sn—C 2.127 (5) and 2.135 (4) Å], two Cl [Sn—Cl 2.5753 (8) Å] and two N atoms [Sn—N 2.357 (3) Å]. The dmpz ligands, bound to the metal through their unprotonated N atoms, form weak intra‐ and intermolecular hydrogen bonds with the Cl ligands via their NH groups, giving rise to a polymeric chain along the c axis.