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Mirror Plane (mirror + plane)
Kinds of Mirror Plane Selected AbstractsAn aza-cyclophane stacked in racemic columnar assemblies: whole-molecule disorder in a two-dimensional solid solutionACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009Matthias Zeller The oxime derivative of [1.1.1]cyclophane cyclotriveratrylene (CTV) was ring expanded utilizing a Beckmann rearrangement to provide a ten-membered N -acetyl macrocyclic amide that crystallizes as a chloroform monosolvate in columnar assemblies manifesting an unusual disorder within the crystal. Columns made up of this structure consist of infinite columnar assemblies of alternating d and l enantiomers and therefore necessarily are made up of a racemate, yet the chiralities of individual molecules in adjacent columns are independent of one another, leading to the overall formation of a two-dimensional solid solution. The random arrangement of the columns within the structure leads to the emergence of a crystallographic mirror plane not reflected by the molecular symmetry, to a change of symmetry from Pna21 to Pnma and to whole-molecule disorder of the bowl-shaped molecules within the columns. [source] Topochemically controlled solid-state methyl rearrangement in thiocyanuratesACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001Mark Greenberg 4,6-Dimethoxy-3-methyl-1,3,5-triazine-2(3H)-thione crystallizes in two polymorphic forms, needles and plates. In the needle-shaped crystals (9a) the molecules occupy the crystallographic mirror plane, thus the layers are stacked along the b axis. The molecules of the other polymorph [plate-shape crystals, (9b)] are packed in a herringbone packing mode. Upon heating, (9b) undergoes a phase transition to form (9a). At 378,K the needles undergo O , S topochemically controlled methyl transfer in the solid state to produce 1-methyl-4-methoxy-6-methylthio-1,3,5-triazine-2(1H)-one in 75% yield. The enthalpy of the rearrangement is estimated to be ,39.1,kJ,mol,1. 1-Methyl-6-methoxy-4-methylthio-1,3,5-triazine-2(1H)-thione crystallizes in space group P21 with two crystallographically independent molecules in the asymmetric unit. Compound (9b) undergoes O , S methyl transfer in the solid state at 373,K. The rearrangement is topochemically assisted and the product, 1-methyl-2,4-bismethylthio-1,3,5-triazine-6(1H)-one, is obtained in quantitative yield. The enthalpy of the rearrangement is estimated to be ,58.8,kJ,mol,1. The crystal structures of the compounds as well as their DSC thermographs are described and discussed. Energy calculation by ab initio methods shows that the driving force for the reactions is the difference between the molecular energies of the pre-rearranged compounds and their products, 54.2 and 59.3,kJ,mol,1 in the two cases, respectively. [source] Poly[dimethyldiphenylphosphonium [di-,4 -iodido-tetra-,3 -iodido-pentacopper(I)]]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2010Ehsan Jalilian The title compound, {(C14H16P)[Cu5I6]}n, prepared from the reaction between copper powder, iodine and dimethyldiphenylphosphonium iodide in hydroxyacetone, features an anion that consists of a continuous two-dimensional Cu,I sheet [Cu,I = 2.5960,(14),2.6994,(13),Å and Cu,I,Cu = 63.28,(5),114.25,(5)°]. The cation, which lies on a mirror plane, is a typical dimethyldiphenylphosphonium ion. The structure shows a strong tendency towards segregation of the inorganic and organic parts of the structure into separate subspaces. The two-dimensional Cu,I sheet displays a pronounced subcell with pseudo-tetragonal symmetry that is broken by ordered vacancies on the Cu position. The symmetry is further reduced by the orientation of the interleaved organic counter-ion that is inclined with respect to the pseudo-mirror planes defined by the Cu,I sheet normal, perpendicular to the b axis. [source] Ba5Cl4(H2O)8(VPO5)8: a novel three-dimensional framework solidACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010Ai-Yun Zhang The novel hydrothermally synthesized title compound, pentabarium tetrachloride octahydrate octakis(oxovanadium phosphate), Ba5Cl4(H2O)8(VPO5)8, crystallizes in the orthorhombic space group Cmca with a unit cell containing four formula units. Two Ba2+ cations, two Cl, anions and the O atoms of four water molecules are situated on the (100) mirror plane, while the third independent Ba2+ cation is on the intersection of the (100) plane and the twofold axis parallel to a. Two phosphate P atoms are on twofold axes, while the remaining independent P atom and both V atoms are in general positions. The structure is characterized by two kinds of layers, namely anionic oxovanadium phosphate (VPO5), composed of corner-sharing VO5 square pyramids and PO4 tetrahedra, and cationic barium chloride hydrate clusters, Ba5Cl4(H2O)8, composed of three Ba2+ cations linked by bridging chloride anions. The layers are connected by Ba,O bonds to generate a three-dimensional structure. [source] Hydrogen-bonded network structures in dipyridinium, bis(2-methylpyridinium), bis(3-methylpyridinium) and bis(4-methylpyridinium) dioxidobis(oxydiacetato)uranate(VI)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010Anders Lennartson Four complexes containing the [UO2(oda)2]2, anion (oda is oxydiacetate) are reported, namely dipyridinium dioxidobis(oxydiacetato)uranate(VI), (C5H6N)2[U(C4H4O5)2O2], (I), bis(2-methylpyridinium) dioxidobis(oxydiacetato)uranate(VI), (C8H8N)2[U(C4H4O5)2O2], (II), bis(3-methylpyridinium) dioxidobis(oxydiacetato)uranate(VI), (C8H8N)2[U(C4H4O5)2O2], (III), and bis(4-methylpyridinium) dioxidobis(oxydiacetato)uranate(VI), (C8H8N)2[U(C4H4O5)2O2], (IV). The anions are achiral and are located on a mirror plane in (I) and on inversion centres in (II),(IV). The four complexes are assembled into three-dimensional structures via N,H...O and C,H...O interactions. Compounds (III) and (IV) are isomorphous; the [UO2(oda)2]2, anions form a porous matrix which is nearly identical in the two structures, and the cations are located in channels formed in this matrix. Compounds (I) and (II) are very different from (III) and (IV): (I) forms a layered structure, while (II) forms ribbons. [source] p -Phenylenediamine and its dihydrate: two-dimensional isomorphism and mechanism of the dehydration process, and N,H...N and N,H..., interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010Agnieszka Czapik p -Phenylenediamine can be obtained as the dihydrate, C6H8N2·2H2O, (I), and in its anhydrous form, C6H8N2, (II). The asymmetric unit of (I) contains one half of the p -phenylenediamine molecule lying about an inversion centre and two halves of water molecules, one lying on a mirror plane and the other lying across a mirror plane. In (II), the asymmetric unit consists of one molecule in a general position and two half molecules located around inversion centres. In both structures, the p -phenylenediamine molecules are arranged in layers stabilized by N,H..., interactions. The diamine layers in (I) are isostructural with half of the layers in (II). On dehydration, crystals of (I) transform to (II). Comparison of their crystal structures suggests the most plausible mechanism of the transformation process which requires, in addition to translational motion of the diamine molecules, in-plane rotation of every fourth p -phenylenediamine molecule by ca 60°. A search of the Cambridge Structural Database shows that the formation of hydrates by aromatic amines should be considered exceptional. [source] Bis[4-(dimethylamino)pyridine-,N1]silver(I) nitrate dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009Al-shima'a A. Massoud The title compound, [Ag(C7H10N2)2]NO3·2H2O or [Ag(dmap)2]NO3·2H2O, where dmap is 4-(dimethylamino)pyridine, has a distorted linear coordination geometry around the AgI ion. A novel pattern of water,nitrate hydrogen-bonded anionic strands is formed in the c direction, with the cationic [Ag(dmap)2]+ monomers trapped between them. The AgI ion and the nitrate group atoms, as well as the water molecules (including the H atoms), are on a crystallographic mirror plane (Wyckoff position 4a). The influence of bulky methyl substituents in position 4 of the 4-(dimethylamino)pyridine ligand on packing is discussed. The absolute structure was determined unequivocally. [source] (E)-3-(4-Methylphenyl)-2-(2-thienyl)acrylonitrile has Z, = 0.75 in the space group C2/m: fourfold disordered molecules lie in channels enclosed by fully ordered moleculesACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009Debora Cobo The title compound, C14H11NS, crystallizes with Z, = 0.75 in the space group C2/m. Two independent molecules are present, one of which lies with all the non-H atoms on a mirror plane, while the other is fourfold disordered across a site of 2/m symmetry. The ordered molecules are stacked such that they enclose continuous channels running along twofold rotation axes, and the disordered molecules are positioned within these channels. [source] Diaquatetrakis(tert -butyl isocyanide)cobalt(II) bis(perchlorate): an example of cobalt(II) coordinated by only four alkyl isocyanide ligandsACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009Clifford A. L. Becker The title compound, [Co(C5H9N)4(H2O)2](ClO4)2, crystallizes in the monoclinic space group C2/m. The cation has space-group-imposed 2/m symmetry, while the perchlorate ion is disordered about a mirror plane. The two slightly non-equivalent Co,C bonds [1.900,(3) and 1.911,(3),Å] form a rectangular plane, with a C,Co,C bond angle of 86.83,(11)°, and the linear O,Co,O C2 axis is perpendicular to this plane. The C[triple-bond]N bond lengths are 1.141,(4),Å and the Co,C[triple-bond]N and C[triple-bond]N,C angles average 175.5,(4)°. The perchlorate counter-ions are hydrogen bonded to the water molecules. The title compound is the first example of four alkyl isocyanide ligands coordinating CoII upon initial reaction of Co(ClO4)2·6H2O/EtOH with alkyl isocyanide. In all other known examples, five alkyl isocyanide molecules are coordinated, as in [(RNC)5Co,Co(CNR)5](ClO4)4 (R = Me, Et, CHMe2, CH2Ph, C4H9 - n or C6H11) or [Co(CNC8H17 - t)5](ClO4)2. This complex, therefore, is unique and somewhat unexpected. [source] Mn3(OAc)6·CH3CN: a porous dehydrated manganese(II) acetateACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2009John Fielden The crystal structure of a new form of dehydrated manganese(II) acetate, poly[[hexa-,3 -acetato-trimanganese(II)] acetonitrile solvate], {[Mn3(CH3COO)6]·CH3CN}n, (I), reveals a three-dimensional polymeric structure based on an {Mn3} trimer. The {Mn3} asymmetric unit contains three crystallographically independent Mn positions, comprising a seven-coordinate center sharing a mirror plane with a six-coordinate center, and another six-coordinate atom located on an inversion center. Two of the four crystallographically independent acetate (OAc) ligands, as well as the acetonitrile solvent molecule, are also located on the mirror plane. The Mn atoms are connected by a mixture of Mn,O,Mn and Mn,OCO,Mn bridging modes, giving rise to face- and corner-sharing interactions between manganese polyhedra within the trimers, and edge- and corner-sharing connections between the trimers. The network contains substantial pores which are tightly filled by crystallographically located acetonitrile molecules. This structure represents the first porous structurally characterized phase of anhydrous manganese(II) acetate and as such it is compared with the closely related densely packed anhydrous manganese(II) acetate phase, solvent-free ,-Mn(OAc)2. [source] A two-dimensional network in the molecular salt 2-methylimidazolium hydrogen glutarate, and three-dimensional networks in the salts 2-methylimidazolium hydrogen succinate and 2-methylimidazolium hydrogen adipate monohydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Xiang-Gao Meng All three title compounds, C4H7N2+·C4H5O4,, (I), C4H7N2+·C5H7O4,, (II), and C4H7N2+·C6H9O4,·H2O, (III), can be regarded as 1:1 organic salts. The dicarboxylic acids join through short acid bridges into infinite chains. Compound (I) crystallizes in the noncentrosymmetric Cmc21 space group and the asymmetric unit consists of a hydrogen succinate anion located on a mirror plane and a 2-methylimidazolium cation disordered across the same mirror. The other two compounds crystallize in the triclinic P space group. The carboxylic acid H atom in (II) is disordered over both ends of the anion and sits on inversion centres between adjacent anions, forming symmetric short O...H...O bridges. Two independent anions in (III) sit across inversion centres, again with the carboxylic acid H atom disordered in short O...H...O bridges. The molecules in all three compounds are linked into two-dimensional networks by combinations of imidazolium,carboxylate N+,H...O and carboxylate,carboxylate O,H...O hydrogen bonds. The two-dimensional networks are further linked into three-dimensional networks by C,H...O hydrogen bonds in (I) and by Owater,H...O hydrogen bonds in (III). According to the ,pKa rule, such 1:1 types of organic salts can be expected unambiguously. However, a 2:1 type of organic salt may be more easily obtained in (II) and (III) than in (I). [source] Orthorhombic aluminium oxyfluoride, AlOFACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Alexander D. Vasiliev Crystals of the title compound were extracted from the bulk of grown SrAlF5 crystals as unexpected inclusions that were identified as the long sought after aluminium oxyfluoride. The structure of AlOF is built up from tetrahedral and octahedral polyhedra. Each tetrahedron is bisected by a mirror plane, with the Al atom and two vertex anions in the plane. All tetrahedral vertices are positions of competing oxide and fluoride ions and are shared with octahedra. These shared vertices belong to two octahedral edges which join the octahedra to form infinite zigzag chains. The chains are strung along twofold screw axes that run parallel to the unit-cell b axis. The remaining two octahedral vertices are occupied only by fluoride ions. A small deficiency in the occupation of the octahedral Al position was suggested by the refinement. However, the stoichiometry of the compound is AlOF within experimental uncertainty. The Al,F(O) distances are separated into three groups with average values of 1.652,(3) (tetrahedra), 1.800,(2) (octahedra) and 1.894,(2),Å (octahedra). This structure differs widely from the reported tetragonal phase Al1,xO1,3xF1+3x (x = 0.0886) [Kutoglu (1992). Z. Kristallogr.199, 197,201], which consists solely of octahedral structural units. [source] The crucial role of C,H...O and C=O..., interactions in the building of three-dimensional structures of dicarboxylic acid,biimidazole compoundsACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Xiao-Li Gao The supramolecular architectures of three dicarboxylic acid,biimidazole compounds, namely, 2,2,-biimidazolium malonate, C6H8N42+·C3H2O42,, (I), 2,2,-bi(1H -imidazole) succinic acid, C6H6N4·C4H6O4, (II), and 2,2,-biimidazolium 2,2,-iminiodiacetate chloride, C6H8N42+·C4H6NO4,·Cl,, (III), are reported. The crystal structures are assembled by the same process, namely double conventional N,H...O or O,H...N hydrogen bonds link the dicarboxylates and biimidazoles to form tapes, which are stacked in parallel through lone-pair,aromatic interactions between carbonyl O atoms and biimidazole groups and are further linked via weak C,H...O interactions. The C=O..., interactions involved in stacking the tapes in (II) and the C,H...O interactions involved in linking the tapes in (II) and (III) demonstrate the crucial role of these interactions in the crystal packing. There is crystallographically imposed symmetry in all three structures. In (I), two independent malonate anions have their central C atoms on twofold axes and two biimidazolium dications each lie about independent inversion centres; in (II), the components lie about inversion centres, while in (III), the unique cation lies about an inversion centre and the iminiodiacetate and chloride anions lie across and on a mirror plane, respectively. [source] Tl2CO3 at 3.56 GPaACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2008A. Grzechnik The crystal structure of thallium carbonate, Tl2CO3 (C2/m, Z = 4), is stable at least up to 3.56,GPa, as demonstrated by hydrostatic single-crystal X-ray diffraction measurements in a diamond anvil cell at room temperature. Our results contradict earlier observations from the literature, which found a structural phase transition for this compound at about 2,GPa. Under atmospheric conditions, all atoms except for one O atom reside on the mirror plane in the high-pressure structure. The compression mainly affects the part of the structure where the nonbonded electron lone pairs on the Tl+ cations are located. [source] 3,3,,5,5,-Tetramethyl-4,4,-bipyrazole,pentafluorophenol (2/3)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2008Konstantin V. Domasevitch In the title compound, 2C10H14N4·3C6HF5O, one of the pentafluorophenol molecules resides on a mirror plane bisecting the O...F axis. The components aggregate by N,H...N, N,H...O and O,H...N hydrogen bonds involving equal disordering of the H atoms into molecular ensembles based on a 2:1 pyrazole,phenol cyclic pattern [O...N = 2.7768,(16),Å and N...N = 2.859,(2),Å], crosslinked into one-dimensional columns via hydrogen bonding between the outer pyrazole groups and additional pentafluorophenol molecules. The latter yields a 1:1 pyrazole,phenol catemer with alternating strong O,H...N [2.5975,(16),Å] and weaker N,H...O [2.8719,(17),Å] hydrogen bonds. This is the first reported molecular adduct of a pentafluorinated phenol and a nitrogen base, and suggests the utility of highly acidic phenols and pyrazoles for developing hydrogen-bonded cocrystals. [source] An unusual syn conformation of 5-formyluracil stabilized by supramolecular interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2007Gustavo Portalone The asymmetric unit of the amino,oxo tautomer of 5-formyluracil (systematic name: 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbaldehyde), C5H4N2O3, comprises one planar amino,oxo tautomer, as every atom in the structure lies on a crystallographic mirror plane. At variance with all the previously reported small-molecule crystal structures containing the 5-formyluracil residue, the formyl substituent in the title compound exhibits an unusual syn conformation. The molecules are linked into planar sheets parallel to the bc plane by a combination of six N,H...O and C,H...O hydrogen bonds. Four of the hydrogen bonds are utilized to stabilize the formyl group in the syn conformation. [source] Two pseudo-polymorphic copper,benzene-1,2,4,5-tetracarboxylate complexesACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2007Jian-Hai Luo Two pseudo-polymorphic polymers, poly[ethylenediammonium [[aquacopper(II)]-,4 -benzene-1,2,4,5-tetracarboxylato] dihydrate], {(C2H10N2)[Cu(C10H2O8)(H2O)]·2H2O}n, (I), and poly[ethylenediammonium [copper(II)-,4 -benzene-1,2,4,5-tetracarboxylato] 2.5-hydrate], {(C2H10N2)[Cu(C10H2O8)]·2.5H2O}n, (II), contain two-dimensional anionic layers, ethylenediammonium (H2en) cations acting as counter-ions and free water molecules. Although the topological structures of the two anionic layers are homologous, the coordination environments of the CuII centres are different. In (I), the CuII centre, sitting on a general position, has a square-pyramidal environment. The two independent benzene-1,2,4,5-tetracarboxylate (btc) anions rest on centres of inversion. The CuII cation in (II) is located on a twofold axis in a square-planar coordination. The H2en cation is on an inversion centre and the btc ligand is split by a mirror plane. Extensive hydrogen-bonding interactions between the complexes, H2en cations and water molecules lead to the formation of three-dimensional supramolecular structures. [source] The layered compound poly[,2 -4,4,-bipyridyl-di-,2 -chlorido-mercury(II)]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2007Yi-Ming Xie The title compound, [HgCl2(C10H8N2)]n, features two-dimensional [HgCl2(4,4,-bipy)]n neutral networks (4,4,-bipy is 4,4,-bipyridine), based on an octahedral Hg atom coordinated by four ,2 -Cl atoms and two ,2 -4,4,-bipy ligands in trans positions, yielding a HgCl4N2 octahedron. The structure has mmm symmetry about the Hg atoms, with most of the atoms on at least one mirror plane, but the unsubstituted C atoms of the 4,4,-bipy rings are disordered across a mirror plane. Photoluminescent investigations reveal that the title compound displays a strong emission in the green region, which probably originates from a ligand-to-ligand charge-transfer transition. [source] 2,4,6-Triamino-1,3,5-triazine,1H -isoindole-1,3(2H)-dione (1/3)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2007Genivaldo Júlio Perpétuo The asymmetric unit of the title compound, C3H6N6·3C8H5NO2, contains a melamine and a phthalimide [1H -isoindole-1,3(2H)-dione] molecule, both residing on a mirror plane, and a second phthalimide molecule residing on a general position. The two components are linked by almost linear N,H...O and N,H...N hydrogen bonds, forming an essentially planar superstructure. These aggregates, related by a twofold screw axis, interact through weak C,H...O contacts, forming chains parallel to the b axis, while those related by translation along the c axis interact via,,, interactions between the , clouds of the aromatic triazine and phthalimide rings to form a stacked structure. [source] Two packing motifs based upon chains of edge-sharing PbI6 octahedraACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2006Andreas Lemmerer The compounds catena -poly[p -phenylenediammonium [[diiodolead(II)]-di-,-iodo] dihydrate], {(C6H10N2)[PbI4]·2H2O}n, (I), and catena -poly[bis(3,5-dimethylanilinium) [[diiodolead(II)]-di-,-iodo]], {(C8H12N)2[PbI4]}n, (II), crystallize as organic,inorganic hybrids. As such, the structures consist of chains of [PbI2], units extending along the c axis in (I) and along the b axis in (II). The asymmetric unit in (I) contains one Pb atom on a site of 2/m symmetry, two I atoms and a water molecule on mirror planes, and a p -phenylenediammonium molecule that sits around a site of 2/m symmetry with the C and N atoms on a mirror plane. In (II), the Pb atom is on a twofold axis and the two I atoms are on general positions. Each Pb atom is octahedrally coordinated to six I atoms, arranged as chains of edge-sharing octahedra. Both compounds undergo hydrogen-bonding interactions between the ammonium groups and the I atoms. In addition, there are hydrogen bonds between the water molecules and the ammonium groups and halides in (I), and between the ammonium groups and the ring systems in (II). [source] Rubidium dimolybdate, Rb2Mo2O7, and caesium dimolybdate, Cs2Mo2O7ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2006Zoya A. Solodovnikova The crystal structures of dirubidium heptaoxodimolybdate, Rb2Mo2O7, and dicaesium heptaoxodimolybdate, Cs2Mo2O7, in the space groups Ama2 and P21/c, respectively, have been determined for the first time by single-crystal X-ray diffraction. The structures represent two novel structure types of monovalent ion dimolybdates, A2Mo2O7 (A = alkaline elements, NH4, Ag or Tl). In the structure of Rb2Mo2O7, Mo atoms are on a twofold axis, on a mirror plane and in a general position. One of the Rb atoms lies on a twofold axis, while three others are on mirror planes. Two O atoms attached to the Mo atom on a mirror plane are located on the same plane. Rubidium dimolybdate contains a new kind of infinite Mo,O chain formed from linked MoO4 tetrahedra and MoO6 octahedra alternating along the a axis, with two terminal MoO4 tetrahedra sharing corners with each octahedron. The chains stack in the [001] direction to form channels of an approximately square section filled by ten-coordinate Rb ions. Seven- and eight-coordinate Rb atoms are located between chains connected by a c translation. In the structure of Cs2Mo2O7, all atoms are in general positions. The MoO6 octahedra share opposite corners to form separate infinite chains running along the c axis and strengthened by bridging MoO4 tetrahedra. The same Mo,O polyhedral chain occurs in the structure of Na2Mo2O7. Eight- to eleven-coordinate Cs atoms fill the space between the chains. The atomic arrangement of caesium dimolybdate has an orthorhombic pseudosymmetry that suggests a possible phase transition P21/c,Pbca at elevated temperatures. [source] Two oxo complexes with tetranuclear [Fe4(,3 -O)2]8+ and trinuclear [Fe3(,3 -O)]7+ unitsACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2006Ana María Atria Two new oxo complexes, namely hexa-,2 -acetato-acetatoaquabis(di-3-pyridylamine)di-,3 -oxo-tetrairon(III) chloride monohydrate ethanol 1.25-solvate, [Fe4(C2H3O2)7O2(C10H9N3)2(H2O)]Cl·1.25C2H6O·H2O, (I), containing a tetranuclear [Fe4(,3 -O)2]8+ unit, and 2-methylimidazolium hexa-,2 -acetato-acetatodiaqua-,3 -oxo-triiron(III) chloride dihydrate, (C4H7N2)[Fe3(C2H3O2)7O(H2O)2]Cl·2H2O, (II), with a trinuclear [Fe3(,3 -O)]7+ unit, are presented. Both structures are formed by two well differentiated entities, viz. a compact isolated cluster composed of FeIII ions coordinated to O2, and CH3CO2, anions, and an external group formed by a central Cl, ion surrounded by different solvent groups to which the anion is bound through hydrogen bonding. In the case of (I), charge balance cannot be achieved within the groups, so the structure is macroscopically ionic; in the case of (II), in contrast, each group is locally neutral owing to the internal compensation of charges. The trinuclear complex crystallizes with the metal cluster, chloride anion and 2-methylimidazolium cation bisected by a crystallographic mirror plane. [source] Pseudo-merohedrally twinned praseodymium hexacyanoferrate(III) tetrahydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2004Vratislav Langer Crystals of the title compound, diaquahexa-,-cyano-ferrate(III)praseodymium(III) dihydrate, Pr[Fe(CN)6]·4H2O or [PrFe(CN)6(H2O)2]·2H2O, are twinned with three components. The Pr atom is coordinated by eight atoms, viz. six N and two symmetry-related water O atoms. The Pr polyhedron (Pr has site symmetry m2m, Wyckoff position 4c) is linked to an FeC6 octahedron (Fe located on a site with imposed 2/m symmetry, Wyckoff position 4b) through N atoms, forming an infinite array. The second (symmetry independent) water molecule lies on a mirror plane, is not included in coordination and is weakly hydrogen bonded to N atoms. [source] Lithium and beryllium hypophosphitesACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2004Dmitry Yu. The structures of monoclinic (C2/m) lithium dihydrogenphosphate, LiH2PO2, and tetragonal (P41212) beryllium bis(dihydrogenphosphate), Be(H2PO2)2, have been determined by single-crystal X-ray diffraction. The structures consist of layers of hypophosphite anions and metal cations in tetrahedral coordination by O atoms. Within the layers, the anions bridge four Li+ and two Be2+ cations, respectively. In LiH2PO2, the Li atom lies on a twofold axis and the H2PO2, anion has the PO2 atoms on a mirror plane. In Be(H2PO2)2, the Be atom lies on a twofold axis and the H2PO2, anion is in a general position. [source] Redetermination of hydronium perchlorate at 193 and 293,KACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2003Azhar A. Rahman A sample of hydronium perchlorate, H3O+·ClO4,, crystallized from ethanol at ambient temperature, was found to be orthorhombic (space group Pnma) at both 193 and 293,K, with no phase transition observed in this temperature range. This contrasts with the earlier observation [Nordman (1962). Acta Cryst. 15, 18,23] of a monoclinic phase (space group P21/n) at 193,K for crystals grown at that temperature from perchloric acid. The hydronium and perchlorate ions lie across a mirror plane but it is not possible to define at either temperature a simple description of the H-atom positions due to the three-dimensional tumbling of the hydronium cation. [source] catena -Poly[[bis[,-1,2-bis(1-methyltetrazol-5-yl)ethane-,2N4:N4,]bis[chlorocopper(II)]]-di-,-chloro]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2003Dmitry O. Ivashkevich In the title compound, [Cu2Cl4(C6H10N8)2]n, the ligand has C2 symmetry, and the Cu and Cl atoms lie on a mirror plane. The coordination polyhedron of the Cu atom is a distorted square pyramid, with the basal positions occupied by two N atoms from two different ligands [Cu,N,=,2.0407,(18),Å] and by the two Cl atoms [Cu,Cl,=,2.2705,(8) and 2.2499,(9),Å], and the apical position occupied by a Cl atom [Cu,Cl,=,2.8154,(9),Å] that belongs to the basal plane of a neighbouring Cu atom. The [CuCl2(C6H10N8)]2 units form infinite chains extending along the a axis via the Cl atoms. Intermolecular C,H,Cl contacts [C,Cl,=,3.484,(2),Å] are also present in the chains. The chains are linked together by intermolecular C,H,N interactions [C,N,=,3.314,(3),Å]. [source] Poly[copper(II)-,-pyrazine-,3 -squarato]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2001Christian Näther In the structure of the title compound, [Cu(C4O4)(C4H4N2)]n, each copper cation is surrounded by three squarate (3,4-dihydroxy-3-cyclobutene-1,2-dioate) anions and two pyrazine ligands, all of which are located in special positions. The copper cation and all atoms of the squarate anion are located on a mirror plane, whereas the pyrazine ligand is located around a mirror plane which is perpendicular to the ring plane. The cations are connected via the squarate anions and the pyrazine ligands, forming sheets parallel to (001). [source] The surprising sp rotameric structure of 9-methyl-9-pivaloylfluoreneACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2000Cal Y. Meyers Methylation of 9-lithiated ap -9-pivaloylfluorene, (I), as well as pivaloylation of 9-lithiated 9-methylfluorene provided rotationally stable sp -9-methyl-9-pivaloylfluorene, (III), C19H20O, which lies about a crystallographic mirror plane. Fluorene (I) exists exclusively in the ap configuration in solution (NMR) as well as in the crystalline state, reflecting the unfavorable interaction between the tert -butyl and fluorene-ring , electrons in the sp configuration. The existence of (III) exclusively in the sp configuration indicates that, in this case, the interaction between the tert -butyl group and the fluorene-ring , electrons provides relatively more thermodynamic stability than the steric interaction between the tert -butyl and 9-methyl groups (ap configuration). [source] 2,3-Dihydro-3-methyl-2-nitrimino-1,3-thiazoleACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2000Janusz Kyzio The title compound {alternatively, 3-methyl-2-[oxido(oxo)hydrazono]-2,3-dihydro-1,3-thiazole}, C4H5N3O2S, was obtained by methylation of N -(2-thiazolyl)nitramine. The molecule lies on a mirror plane and the thiazole ring is planar, regular in shape and aromatic. The S atom participates in the aromatic sextet via an electron pair on the 3pz orbital. In the crystal, the molecules are arranged in parallel layers, bound to each other by weak C,H,O and C,H,N hydrogen bonds and by S,O dipolar interactions, with an interlayer separation of 3.23,Å. [source] 13H -Dibenzo[a,i]fluoren-13-oneACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2000David G. Morris Molecules of 13H -dibenzo[a,i]fluoren-13-one, C21H12O, straddle a crystallographic mirror plane and are essentially planar, with a dihedral angle of only 1.9,(1)° between the two naphthalene ring systems. Repulsive intramolecular C=O,H interactions therefore do not explain the larger distortions found in isomeric ketones. [source] | ||||||||||