The isotypic hydrogen phosphate and arsenate dihydratesM2HXO4·2H2O (M= Rb, Cs;X= P, As)

2013 ◽  
Vol 70 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Berthold Stöger ◽  
Matthias Weil

The four isotypic alkaline metal monohydrogen arsenate(V) and phosphate(V) dihydratesM2HXO4·2H2O (M= Rb, Cs;X = P, As) [namely dicaesium monohydrogen arsenate(V) dihydrate, Cs2HAsO4·2H2O, dicaesium monohydrogen phosphate(V) dihydrate, Cs2HPO4·2H2O, dirubidium monohydrogen arsenate(V) dihydrate, Rb2HAsO4·2H2O, and dirubidium monohydrogen phosphate(V) dihydrate, Rb2HPO4·2H2O] were synthesized by reaction of an aqueous H3XO4solution with one equivalent of aqueousM2CO3. Their crystal structures are made up of undulating chains extending along [001] of tetrahedral [XO3(OH)]−anions connectedviastrong O—H...O hydrogen bonds. These chains are in turn connected into a three-dimensional networkviamedium-strength hydrogen bonding involving the water molecules. Two crystallographically differentM+cations are located in channels running along [001] or in the free space of the [XO3(OH)]−chains, respectively. They are coordinated by eight and twelve O atoms forming irregular polyhedra. The structures possess pseudosymmetry. Due to the ordering of the protons in the [XO3(OH)]−chains in the actual structures, the symmetry is reduced fromC2/ctoP21/c. Nevertheless, the deviation fromC2/csymmetry is minute.

Author(s):  
Graham Smith ◽  
Urs D. Wermuth

In the structure of the brucinium salt of 4-aminophenylarsonic acid (p-arsanilic acid), systematically 2,3-dimethoxy-10-oxostrychnidinium 4-aminophenylarsonate tetrahydrate, (C23H27N2O4)[As(C6H7N)O2(OH)]·4H2O, the brucinium cations form the characteristic undulating and overlapping head-to-tail layered brucine substructures packed along [010]. The arsanilate anions and the water molecules of solvation are accommodated between the layers and are linked to them through a primary cation N—H...O(anion) hydrogen bond, as well as through water O—H...O hydrogen bonds to brucinium and arsanilate ions as well as bridging water O-atom acceptors, giving an overall three-dimensional network structure.


2014 ◽  
Vol 70 (4) ◽  
pp. 396-399 ◽  
Author(s):  
Christian Neis ◽  
Kaspar Hegetschweiler

In the title monohydrated cocrystal, namely 1,3-diamino-5-azaniumyl-1,3,5-trideoxy-cis-inositol iodide–1,3,5-triamino-1,3,5-trideoxy-cis-inositol–water (1/1/1), C6H16N3O3+·I−·C6H15N3O3·H2O, the neutral 1,3,5-triamino-1,3,5-trideoxy-cis-inositol (taci) molecule and the monoprotonated 1,3-diamino-5-azaniumyl-1,3,5-trideoxy-cis-inositol cation (Htaci+) both adopt a chair conformation, with the three O atoms in axial and the three N atoms in equatorial positions. The cation, but not the neutral taci unit, exhibits intramolecular O—H...O hydrogen bonding. The entire structure is stabilized by a complex three-dimensional network of intermolecular hydrogen bonds. The neutral taci entities and the Htaci+cations are each aligned into chains along [001]. In these chains, two O—H...N interactions generate a ten-membered ring as the predominant structural motif. The rings consist of vicinal 2-amino-1-hydroxyethylene units of neighbouring molecules, which are pairedviacentres of inversion. The chains are interconnected into undulating layers parallel to theacplane, and the layers are further held together by O—H...N hydrogen bonds and additional interactions with the iodide counter-anions and solvent water molecules.


2011 ◽  
Vol 66 (2) ◽  
pp. 164-176
Author(s):  
Ioannis Tiritiris ◽  
Willi Kantlehner

The alkylammonium alkylcarbamates 2, 4a,b, 14 were prepared from the amines 1, 3a,b, 13 and CO2. The crystal structures of 2 and 4b show carbamate anions, which are connected by N-H···O hydrogen bonds to form centrosymmetric dimers. The zwitterionic carbamates 7a,b, 8a,b and 11 are formed in the reactions of the diamines 6a,b and 10 with CO2. The crystal structures of 7a and 8b show strong intermolecular hydrogen bonds involving water molecules, the ammonium and the carbamate groups. In these compounds the molecules are interconnected in an extended two- or three-dimensional network. Due to the absence of crystal water molecules, the structure of 11 contains intermolecular hydrogen bonds involving the ammonium and the carbamate group in double-stranded chains. The diamines 17a,b react with CO2 to give the zwitterionic carbamates 18a,b.


1999 ◽  
Vol 54 (1) ◽  
pp. 103-108 ◽  
Author(s):  
Stephanie Janeda ◽  
Dietrich Mootz

The crystal structures of five low-melting hydrates of n-alkane-α,ω-diamines, H2N(CH2)nNH2 · x H2O, for short Cn · x W, have been determined. As a common feature, the water molecules are mutually linked by hydrogen bonds O-H· · ·O to form low-dimensional polymers. These are a meandering chain in C2 · 2 W (space group I 2/a, Z = 4 formula units per unit cell), a zig zag chain in C6 · 2 W (P 21/c, Z = 2), a ribbon of consecutively condensed five-membered rings in C3 · 3 W (P 21/c, Z = 4) and a layer of condensed and spiro-linked rings of varying size each in C7 · 3 W (P 1̄, Z = 4) and C4 · 5 W (C 2/c, Z = 4). Further hydrogen bonding, between the water polymers and the bifunctional amine molecules, leads to overall connectivities which are three-dimensional in each structure.


2014 ◽  
Vol 70 (8) ◽  
pp. 54-57 ◽  
Author(s):  
Matthias Weil ◽  
Barbara Bonneau

The crystal structures of Na2SeO4·1.5H2O (sodium selenate sesquihydrate) and Na2SeO4·10H2O (sodium selenate decahydrate) are isotypic with those of Na2CrO4·1.5H2O and Na2XSeO4·10H2O (X= S, Cr), respectively. The asymmetric unit of the sesquihydrate contains two Na+cations, one SeO4tetrahedron and one and a half water molecules, the other half being generated by twofold rotation symmetry. The coordination polyhedra of the cations are a distorted monocapped octahedron and a square pyramid; these [NaOx] polyhedra are linked through common edges and corners into a three-dimensional framework structure, the voids of which are filled with the Se atoms of the SeO4tetrahedra. The structure is consolidated by O—H...O hydrogen bonds between coordinating water molecules and framework O atoms. The asymmetric unit of the decahydrate consists of two Na+cations, one SeO4tetrahedron and ten water molecules. Both Na+cations are octahedrally surrounded by water molecules and by edge-sharing condensed into zigzag chains extending parallel to [001]. The SeO4tetrahedra and two uncoordinating water molecules are situated between the chains and are connected to the chains through an intricate network of medium-strength O—H...O hydrogen bonds.


IUCrData ◽  
2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Matthias Weil

In comparison with the previous structure determination of poly[diaquadi-μ-formato-nickel(II)], [Ni(HCOO)2(H2O)2]n, based on Weissenberg film data [Krogmann & Mattes (1963).Z. Kristallogr.118, 291–302], the current redetermination from modern CCD data revealed the positions of the H atoms, thus making a detailed description of the hydrogen-bonding pattern possible. Both Ni2+cations in the crystal structure are located on inversion centres and are octahedrally coordinated. One Ni2+cation is bound to six O atoms of six formate anions whereas the other Ni2+cation is bound to four O atoms of water molecules and to two formate O atoms. In this way, the formate anions bridge the two types of Ni2+cations into a three-dimensional framework. O—H...O hydrogen bonds of medium strength between water molecules and formate O atoms consolidate the packing.


2009 ◽  
Vol 65 (6) ◽  
pp. o1329-o1329
Author(s):  
Li-Yan Dai ◽  
Fu-Liang Zhang ◽  
Liang Shen ◽  
Ying-Qi Chen

In the title compound, C8H12N2·H2O, four substituted pyridine molecules alternate with four water molecules, forming a large ringviaOwater—H...Npyridineand Namine—H...Owaterhydrogen bonding. Adjacent rings are connectedviaOwater—H...Owaterhydrogen-bonds, forming a three-dimensional network.


Author(s):  
Edson T. Mukombiwa ◽  
William T A Harrison

The syntheses and crystal structures of three molecular salts of protonated 3,4-diaminobenzoic acid, viz. 2-amino-5-carboxyanilinium chloride, C7H9N2O2 +·Cl−, (I), 2-amino-5-carboxyanilinium bromide, C7H9N2O2 +·Br−, (II), and 2-amino-5-carboxyanilinium nitrate monohydrate, C7H9N2O2 +·NO3 −·H2O, (III), are described. The cation is protonated at the meta-N atom (with respect to the carboxy group) in each case. In the crystal of (I), carboxylic acid inversion dimers linked by pairwise O—H...O hydrogen bonds are seen and each N—H group forms a hydrogen bond to a chloride ion to result in (100) undulating layers of chloride ions bridged by the inversion dimers into a three-dimensional network. The extended structure of (II) features O—H...Br, N—H...Br and N—H...O hydrogen bonds: the last of these generates C(7) chains of cations. Overall, the packing in (II) features undulating (100) sheets of bromide ions alternating with the organic cations. Intermolecular interactions in the crystal of (III) include O—H...O, O—H...(O,O), N—H...O, N—H...N and O—H...N links. The cations are linked into (001) sheets, and the nitrate ions and water molecules form undulating chains. Taken together, alternating (001) slabs of organic cations plus anions/water molecules result. Hirshfeld surfaces and fingerprint plots were generated to give further insight into the intermolecular interactions in these structures. The crystal used for the data collection of (II) was twinned by rotation about [100] in reciprocal space in a 0.4896 (15):0.5104 (15) ratio.


Author(s):  
Tristan Neumann ◽  
Inke Jess ◽  
Christian Näther

Reaction of Co(NCS)2 and Zn(NCS)2 with 4-pyridinethioamide led to the formation of compounds with composition [Co(NCS)2(C6H6N2S)4]·H2O (1) and [Zn(NCS)2(C6H6N2S)2] (2), respectively. The asymmetric unit of compound 1, consists of one cobalt(II) cation, two thiocyanate anions, four 4-pyridinethioamide ligands and one water molecule whereas that of compound 2 comprises one zinc(II) cation that is located on a twofold rotation axis as well as one thiocyanate anion and one 4-pyridinethioamide ligand in general positions. In the structure of compound 1, the cobalt(II) cations are octahedrally coordinated by two terminal N-bonding thiocyanate anions and by the N atoms of four 4-pyridinethioamide ligands, resulting in discrete and slightly distorted octahedral complexes. These complexes are linked into a three-dimensional network via intermolecular N—H...S hydrogen bonding between the amino H atoms and the thiocyanate S atoms. From this arrangement, channels are formed in which the water molecules are embedded and linked to the host structure by intermolecular O—H...S and N—H...O hydrogen bonding. In the structure of compound 2, the zinc(II) cations are tetrahedrally coordinated by two N-bonding thiocyanate anions and the N atoms of two 4-pyridinethioamide ligands into discrete complexes. These complexes are likewise connected into a three-dimensional network by intermolecular N—H...S hydrogen bonding between the amino H atoms and the thioamide S atoms.


2018 ◽  
Vol 33 (2) ◽  
pp. 98-107 ◽  
Author(s):  
James A. Kaduk

The crystal structures of calcium citrate hexahydrate, calcium citrate tetrahydrate, and anhydrous calcium citrate have been solved using laboratory and synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Both the hexahydrate and tetrahydrate structures are characterized by layers of edge-sharing Ca coordination polyhedra, including triply chelated Ca. An additional isolated Ca is coordinated by water molecules, and two uncoordinated water molecules occur in the hexahydrate structure. The previously reported polymorph of the tetrahydrate contains the same layers, but only two H2O coordinated to the isolated Ca and two uncoordinated water molecules. Anhydrous calcium citrate has a three-dimensional network structure of Ca coordination polyhedra. The new polymorph of calcium citrate tetrahydrate is the major crystalline phase in several commercial calcium supplements.


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