Inversion Twin Research Articles

2,3-Dimethyl-1H-imidazol-3-ium chloride.

The title salt, C5H9N2 +·Cl-, exhibits multiple hydrogen-bonding inter-actions between the cationic imidazole moiety and the chloride anion. The protonated aromatic nitro-gen moiety displays the shortest hydrogen-bonding inter-actions while weaker hydrogen bonding is observed between the aromatic H atoms and the chloride anion. The crystal studied was refined as a two-component inversion twin with a twin ratio of 0.71 (5) to 0.29 (5).

CaNa[Cr(OH)6] – A Layered Hydroxochromate(III) with Ordered Brucite Structure and its Thermal Decomposition

Green single‐crystals of the hydroxochromate(III) CaNa[Cr(OH)6] were grown under highly alkaline hydrothermal conditions at about 200 °C. The starting materials Ca(NO3)2·6H2O and Cr(NO3)3·9H2O were reacted in a mixture of water and sodium hydroxide with the molar ratio of 2.8:1. CaNa[Cr(OH)6] crystallizes in the non‐centrosymmetric trigonal space group R3 with the lattice parameters a = 583.86(2) pm and c = 1428.73(6) pm [T = 100(1) K]. Characteristically, the crystals are reverse‐obverse as well as inversion twins. The crystal structure is a stack of uncharged metal hydroxide layers, which can be regarded as a cation‐ordered rhombohedral variant of the Mg(OH)2 (brucite) structure type. The oxidation state of chromium(III) and its coordination by hydroxide groups was confirmed by UV/Vis and IR spectroscopy, respectively. Temperature‐dependent magnetic measurements revealed paramagnetic behavior with an effective moment of 3.82 μB per chromium atom. The thermal decomposition of CaNa[Cr(OH)6] takes place at about 225 °C, where the fast elimination of 1.5 equivalents of water is followed by the oxidation of chromium(III) to chromium(VI). Upon further heating to 1000 °C and 1200 °C, the intermediate decomposition products CaCrO4 and Na2CrO4 transform into the oxochromates(V) Ca5(CrO4)3O0.5 and Ca3(CrO4)2, respectively.

Crystal structures and comparisons of huntite aluminum borates REAl3(BO3)4 (RE = Tb, Dy and Ho).

Three huntite-type aluminoborates of stoichiometry REAl3(BO3)4 (RE = Tb, Dy and Ho), namely, terbium/dysprosium/holmium trialuminium tetrakis(borate), were synthesized by slow cooling within a K2Mo3O10 flux with spontaneous crystallization. The crystal structures were determined using single-crystal X-ray diffraction (SC-XRD) data. The synthesized borates are isostructural to the huntite [CaMg3(CO3)4] structure and crystallized within the trigonal R32 space group. The structural parameters were compared to literature data of other huntite REAl3(BO3)4 crystals within the R32 space group. All three borates fit well into the trends calculated from the literature data. The unit-cell parameters and volumes increase linearly with larger RE cations whereas the densities decrease. All of the crystals studied were refined as inversion twins.

Crystal structures of 2,3,7,8,12,13,17,18-octa-bromo-5,10,15,20-tetra-kis-(penta-fluoro-phen-yl)porphyrin as the chloro-form monosolvate and tetra-hydro-furan monosolvate.

The crystal structures of the title compounds, two solvates (CHCl3 and THF) of a symmetric and highly substituted porphyrin, C44H2Br8F20N4 or OBrTPFPP, are described. These structures each feature a non-planar porphyrin ring, exhibiting a similar conformation of the strained ring independent of solvent identity. These distorted porphyrins are able to form hydrogen bonds and sub-van der Waals halogen inter-actions with enclathrated solvent; supra-molecular inter-actions of proximal macrocycles are additionally affected by solvent choice. The crystal studied for compound 1·CHCl3 was refined as an inversion twin. One penta-fluoro-phenyl group was modelled as disordered over two sites [occupancy ratio = 0.462 (7):0.538 (7)]. The chloro-form solvate was also modelled as disordered over two orientations [occupancy ratio = 0.882 (7): 0.118 (7).

The varied structures of cobalt(II)-pyridine (py)-sulfate: [Co(SO4)(py)4] n , [Co2(SO4)2(py)6] n , and [Co3(SO4)3(py)11] n.

The solid-state structures of two cobalt-pyridine-sulfate compounds, namely catena-poly[[tetra-kis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ2 O:O'], [Co(SO4)(C5H5N)4] n , (1), and catena-poly[[tetra-kis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ3 O:O',O''-[bis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ3 O,O':O''] n , [Co2(SO4)2(C5H5N)6] n , (2), are reported. Compound (1) displays a polymeric structure, with infinite chains of CoII cations adopting octa-hedral N4O2 coordination environments that involve four pyridine ligands and two bridging sulfate ions. Compound (2) is also polymeric with infinite chains of CoII cations. The first Co center has an octa-hedral N4O2 coordination environment that involves four pyridine ligands and two bridging sulfate ligands. The second Co center has an octa-hedral N2O4 coordination environment that involves two pyridine ligands and two bridging sulfate ions that chelate the Co atom. The structure of (2) was refined as a two-component inversion twin.

Intrinsic Ferroelectricity in Charge-Ordered Magnetite

Single crystalline magnetite Fe 3 O 4 was investigated at low temperatures in the charge ordered state by electric measurements and time-resolved diffraction with voltage applied in-situ. Dielectric spectroscopy indicates relaxor ferroelectric characteristics, with polarization switching observably only at sufficiently low temperatures and in a suitably chosen time-window. PUND measurements with a ms time scale indicate a switchable polarization of about 0 . 6 μ C / cm 2 . Significant switching occurs only above a threshold field of about 3 kV / mm , and it occurs with a time delay of about 20 μ s . The time-resolved diffraction experiment yields, for sufficiently high voltage pulses, a systematic variation by about 0 . 1 % of the intensity of the ( 2 , 2 ¯ , 10 ¯ ) Bragg reflection, which is attributed to structural switching of domains of the non-centrosymmetric C c structure to its inversion twins, providing proof of intrinsic ferroelectricity in charge ordered magnetite.

Crystal structures of two charge-transfer com-plexes of benzo[1,2-c:3,4-c':5,6-c'']tri-thio-phene (D 3h -BTT).

Benzo[1,2-c:3,4-c':5,6-c'']tri-thio-phene (D 3h -BTT) is an easily prepared electron donor that readily forms charge-transfer complexes with organic acceptors. We report here two crystal structures of its charge-transfer complexes with 7,7,8,8-tetra-cyano-quinodi-methane (TCNQ) and buckminsterfullerene (C60). The D 3h -BTT·TCNQ complex, C12H6S3·C12H4N4, crystallizes with mixed layers of donors and acceptors, with an estimated degree of charge transfer at 0.09 e. In the D 3h -BTT·C60·toluene complex, C12H6S3·C60·C7H8, the central ring of BTT is 'squeezed' by the C60 mol-ecules from both faces. However, the degree of charge transfer is low. The C60 unit is disordered over two sites in a 0.766 (3):0.234 (3) ratio and was refined as a two-component inversion twin.

Crystal structure and Hirshfeld surface analysis of N-(tert-but-yl)-2-(phenyl-ethyn-yl)imidazo[1,2-a]pyridin-3-amine.

The bicyclic imidazo[1,2-a]pyridine core of the title compound, C19H19N3, is relatively planar with an r.m.s. deviation of 0.040 Å. The phenyl ring is inclined to the mean plane of the imidazo[1,2-a]pyridine unit by 18.2 (1)°. In the crystal, mol-ecules are linked by N-H⋯H hydrogen bonds, forming chains along the c-axis direction. The chains are linked by C-H⋯π inter-actions, forming slabs parallel to the ac plane. The Hirshfeld surface analysis and fingerprint plots reveal that the crystal structure is dominated by H⋯H (54%) and C⋯H/H⋯C (35.6%) contacts. The crystal studied was refined as an inversion twin.

Crystal structure of tetra-kis-(tetra-hydro-furan-κO)bis-(tri-fluoro-methane-sulfonato-κO)iron(II).

The title compound, [Fe(CF3SO3)2(C4H8O)4], is octa-hedral with two tri-fluoro-methane-sulfonate ligands in trans positions and four tetra-hydro-furane mol-ecules in the equatorial plane. By the conformation of the ligands the complex is chiral in the crystal packing. The compound crystallizes in the Sohncke space group P212121 and is enanti-omerically pure. The packing of the mol-ecules is determined by weak C-H⋯O hydrogen bonds. The crystal studied was refined as a two-component inversion twin.

The crystal structure of the zwitterionic co-crystal of 2,4-di-chloro-6-{[(3-hy-droxy-prop-yl)azaniumyl]-meth-yl}phenolate and 2,4-di-chloro-phenol.

The title compound, C10H13Cl2NO2·C6H4Cl2O, was formed from the incomplete Mannich condensation reaction of 3-amino-propan-1-ol, formaldehyde and 2,4-di-chloro-phenol in methanol. This resulted in the formation of a co-crystal of the zwitterionic Mannich base, 2,4-di-chloro-6-{[(3-hy-droxy-prop-yl)azaniumyl]-meth-yl}phenolate and the unreacted 2,4-di-chloro-phenol. The compound crystallizes in the monoclinic crystal system (in space group Cc) and the asymmetric unit contains a mol-ecule each of the 2,4-di-chloro-phenol and 2,4-di-chloro-6-{[(3-hy-droxy-prop-yl)azaniumyl]-meth-yl}phenolate. Examination of the crystal structure shows that the two components are clearly linked together by hydrogen bonds. The packing patterns are most inter-esting along the b and the c axes, where the co-crystal in the unit cell packs in a manner that shows alternating aromatic di-chloro-phenol fragments and polar hydrogen-bonded channels. The 2,4-di-chloro-phenol rings stack on top of one another, and these are held together by π-π inter-actions. The crystal studied was refined as an inversion twin.

The structure and Hirshfeld surface analysis of the salt 3-methacryl-amido-N,N,N-tri-methyl-propan-1-aminium 2-acryl-amido-2-methyl-propane-1-sulfonate.

The title salt, C10H21N2O+·C7H12NO4S-, comprises a 3-methacryl-amido-N,N,N-tri-methyl-propan-1-aminium cation and a 2-acryl-amido-2-methyl-propane-1-sulfonate anion. The salt crystallizes with two unique cation-anion pairs in the asymmetric unit of the ortho-rhom-bic unit cell. The crystal studied was an inversion twin with a 0.52 (4):0.48 (4) domain ratio. In the crystal, the cations and anions stack along the b-axis direction and are linked by an extensive series of N-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional network. Hirshfeld surface analysis was carried out on both the asymmetric unit and the two individual salts. The contribution of inter-atomic contacts to the surfaces of the individual cations and anions are also compared.

Crystal structure of (1S,2R)-2-[(3R,4S)-3-methyl-4-phenyl-1,2,3,4-tetra-hydro-isoquinolin-2-yl]-1,2-di-phenyl-ethanol.

The synthesis and crystal structure of the title compound, C30H29NO, are described. This compound is a member of the chiral di-hydro-iso-quinoline-derived family, used as building blocks for functional materials and as source of chirality in asymmetric synthesis, and was isolated as one of two diastereomeric β-amino alcohols, the title mol-ecule being found to be the (S,R) diastereoisomer. In the crystal, mol-ecules are packed in a herringbone manner parallel to (103) and (10) via weak C-H⋯O and C-H⋯π(ring) inter-actions. Hirshfeld surface analysis showed that the surface contacts are predominantly H⋯H inter-actions (ca 75%). The crystal studied was refined as a two-component inversion twin.

Poly[[μ4-4-(carboxylatomethyl)benzoato]zinc(II)

In the title compound, [Zn(C9H6O4)] n , the ZnII cations are coordinated in a tetrahedral fashion by carboxylate O-atom donors belonging to four 4-(carboxymethyl) benzoate (4-cmb) ligands. Each 4-cmb ligand binds to four ZnII cations in an exotetradentate fashion to create a non-interpenetrated [Zn(4-cmb)] n three-dimensional coordination polymer network with a new non-diamondoid 66 topology. The crystal studied was refined as an inversion twin.

Catena-Poly[[diaquacadmium(II)]-μ2-3-(4-carboxylatophenyl)propionato

In the title compound, [Cd(C10H8O4)(H2O)2)] n , the CdII cation is coordinated in a distorted trigonal–prismatic fashion. 3-(4-Carboxyphenyl)propionate (cpp) ligands connect the CdII cations into zigzag [Cd(cpp)(H2O)2)] n coordination polymer chains, which are oriented parallel to [101]. The chains aggregate into supramolecular layers oriented parallel to (10\overline{1}) by means of O—H...O hydrogen bonding between bound water molecules and ligating cpp carboxylate O atoms. The layers stack in an ABAB pattern along [100] via other O—H...O hydrogen-bonding mechanisms also involving the bound water molecules. The crystal studied was an inversion twin.

Crystal structures and Hirshfeld surface analyses of the two isotypic compounds (E)-1-(4-bromo-phen-yl)-2-[2,2-di-chloro-1-(4-nitro-phen-yl)ethen-yl]diazene and (E)-1-(4-chloro-phen-yl)-2-[2,2-di-chloro-1-(4-nitro-phen-yl)ethen-yl]diazene.

In the two isotypic title compounds, C14H8BrCl2N3O2, (I), and C14H8Cl3N3O2, (II), the substitution of one of the phenyl rings is different [Br for (I) and Cl for (II)]. Aromatic rings form dihedral angles of 60.9 (2) and 64.1 (2)°, respectively. Mol-ecules are linked through weak X⋯Cl contacts [X = Br for (I) and Cl for (II)], C-H⋯Cl and C-Cl⋯π inter-actions into sheets parallel to the ab plane. Additional van der Waals inter-actions consolidate the three-dimensional packing. Hirshfeld surface analysis of the crystal structures indicates that the most important contributions for the crystal packing for (I) are from C⋯H/H⋯C (16.1%), O⋯H/H⋯O (13.1%), Cl⋯H/H⋯Cl (12.7%), H⋯H (11.4%), Br⋯H/H⋯Br (8.9%), N⋯H/H⋯N (6.9%) and Cl⋯C/C⋯Cl (6.6%) inter-actions, and for (II), from Cl⋯H / H⋯Cl (21.9%), C⋯H/H⋯C (15.3%), O⋯H/H⋯O (13.4%), H⋯H (11.5%), Cl⋯C/C⋯Cl (8.3%), N⋯H/H⋯N (7.0%) and Cl⋯Cl (5.9%) inter-actions. The crystal of (I) studied was refined as an inversion twin, the ratio of components being 0.9917 (12):0.0083 (12).

Bis(15-crown-5-κ5 O)barium tetrakis(isothiocynato-κN)zinc(II)

In the title compound, [Ba(C10H20O5)2][Zn(NCS)4], the 15-crown-5 molecules are disordered over two positions with site occupancies of 0.706 (4) and 0.294 (4). The Ba2+ ions are sandwiched between the 15-crown-5 rings and Zn2+ ions are surrounded by four N atoms from the thiocyanate ligands in a distorted tetrahedral geometry. The crystal studied was refined as an inversion twin.

Investigation of an Unusual Crystal Habit of Hydrochlorothiazide Reveals Large Polar Enantiopure Domains and a Possible Crystal Nucleation Mechanism

AbstractThe observation of an unusual crystal habit in the common diuretic drug hydrochlorothiazide (HCT), and identification of its subtle conformational chirality, has stimulated a detailed investigation of its crystalline forms. Enantiomeric conformers of HCT resolve into an unusual structure of conjoined enantiomorphic twin crystals comprising enantiopure domains of opposite chirality. The purity of the domains and the chiral molecular conformation are confirmed by spatially revolved synchrotron micro‐XRD experiments and neutron diffraction, respectively. Macroscopic inversion twin symmetry observed between the crystal wings suggests a pseudoracemic structure that is not a solid solution or a layered crystal structure, but an unusual structural variant of conglomerates and racemic twins. Computed interaction energies for molecular pairs in the racemic and enantiopure polymorphs of HCT, and the observation of large opposing unit‐cell dipole moments for the enantiopure domains in these twin crystals, suggest a plausible crystal nucleation mechanism for this unusual crystal habit.

Investigation of an Unusual Crystal Habit of Hydrochlorothiazide Reveals Large Polar Enantiopure Domains and a Possible Crystal Nucleation Mechanism.

The observation of an unusual crystal habit in the common diuretic drug hydrochlorothiazide (HCT), and identification of its subtle conformational chirality, has stimulated a detailed investigation of its crystalline forms. Enantiomeric conformers of HCT resolve into an unusual structure of conjoined enantiomorphic twin crystals comprising enantiopure domains of opposite chirality. The purity of the domains and the chiral molecular conformation are confirmed by spatially revolved synchrotron micro-XRD experiments and neutron diffraction, respectively. Macroscopic inversion twin symmetry observed between the crystal wings suggests a pseudoracemic structure that is not a solid solution or a layered crystal structure, but an unusual structural variant of conglomerates and racemic twins. Computed interaction energies for molecular pairs in the racemic and enantiopure polymorphs of HCT, and the observation of large opposing unit-cell dipole moments for the enantiopure domains in these twin crystals, suggest a plausible crystal nucleation mechanism for this unusual crystal habit.

(E)-4-Iodo-2-[(phenylimino)methyl]phenol

The title compound, C13H10INO, is not planar as the dihedral angle between the planes of the two aryl rings is 44.5 (9)°. The configuration about the central C=N bond is E, and there is an intramolecular O—H...N hydrogen bond which generates an S(6) ring. The molecular packing is stabilized by weak C—H...π interactions. The structure was refined as a two-component inversion twin.

Crystal structure of bis(μ-{2-[(5-bromo-2-oxido-benzyl-idene)amino]-eth-yl}sulfanido-κ3 N,O,S){2,2'-[(3,4-di-thia-hexane-1,6-di-yl)bis-(nitrilo-methanylyl-idene)]bis-(4-bromo-phenolato)-κ4 O,N,N',O'}dicobalt(III) di-methyl-formamide monosolvate.

The title binuclear CoIII complex, [Co2(C9H8BrNOS)2(C18H16Br2N2O2S2)]·C3H7NO, with a Schiff base ligand formed in situ from cyste-amine (2-amino-ethane-thiol) and 5-bromo-salicyl-aldehyde crystallizes in the space group P21. It was found that during the synthesis the ligand undergoes spontaneous oxidation, forming the new ligand H2 L' having an S-S bond. Thus, the asymmetric unit consists of one Co2(L)2(L') mol-ecule and one DMF solvent mol-ecule. Each CoIII ion has a slightly distorted octa-hedral S2N2O2 coordination geometry. In the crystal, the components are linked into a three-dimensional network by several S⋯ Br, C⋯ Br, C-H⋯Br, short S⋯C (essentially shorter than the sum of the van der Waals radii for the atoms involved) contacts as well by weak C-H⋯O hydrogen bonds. The crystal studied was refined as an inversion twin.