Volume 227, Issue 9 -

Single crystals of Na 2 CrO 4 × 10 H 2 O ( I ) and Na 2 CrO 4 × 1.5 H 2 O ( II ) were synthesized from an aqueous solution of sodium chromate by isothermal evaporation of the solvent. The crystal structures of both compounds were determined from X-ray single crystal diffraction experiments performed at –100 °C. Basic crystallographic data of the phases are as follows: ( I ) monoclinic, space group P 2 1 /c , a = 11.5356(12) Å, b = 10.4989(9) Å, c = 12.9454(13) Å, β = 107.489(8)°, V = 1495.4(2) Å 3 , Z = 4; ( II ) orthorhombic, space group F 2 dd , a = 6.7797(8) Å, b = 8.6548(10) Å, c = 35.078(5) Å, V = 2058.3(5) Å 3 , Z = 16. The decahydrate is isostructural with the corresponding sulfate compound (Glauber’s salt or mirabilite). The two crystallographically independent sodium atoms in ( I ) are coordinated by six water molecules each in form of distorted octahedra. The octahedra are linked together by edge-sharing in chains parallel to the c -axis. The periodicity of a single chain is four. The [CrO 4 ]-tetrahedra are disordered among two positions. The sesquihydrate ( II ) represents a new structure type. The sodium cations are coordinated in form of distorted [NaO 4 (H 2 O) 2 ]-octahedra as well as [NaO 4 (H 2 O)]-pyramids. The octahedra share common edges. The resulting zig-zag chains represent the backbone of the structure and run along [110] and [1-10], respectively. The chains have a width of about 3.2 Å and are concentrated in layers parallel to (001). Within a single layer neighbouring chains are connected by [CrO 4 ]-tetrahedra and additional hydrogen bonds. Linkage between different layers is provided by sheets containing corner sharing tetragonal pyramids, with four oxygen atoms defining the basal plane and an additional water molecule forming the apex. The present investigation confirms the existence of a sesquihydrate in the system Na 2 CrO 4 —H 2 O which has been a matter of debate in the literature.

Structures of new barium dicarboxylates (salts of glutaric, adipic, pimelic, suberic, azelaic and dodecanedioic acids { 1–6 }) were characterized. Structure solution from powder data was performed in the cases of barium adipate { 2 }, pimelate monohydrate { 3 } and dodecanedioate { 6 }. Structures of barium glutarate pentahydrate { 1 }, suberate { 4 } and azelate { 5 } were obtained from single crystal analysis. Even though these compounds are salts of homologus series of dicarboxylic acids [HOOC—C n H 2 n —COOH; n = (3–10)], the obtained materials are characterized by broad structural diversity. The synthesized salts form layered (2D) or three-dimensional (3D) structures. Coordination polyhedra of BaO n (8 or 9) – create layers or linear systems of polyhedra connected by edges or edges and vertices, or layers formed by isolated polyhedra linked by carboxylic acids. The degree of hydratation ranges from 5 to 0; the obtained materials crystallize in various crystallographic systems, from triclinic to tetragonal.

A rare-topology [Mn II 4 ]-core complex [Mn 4 Br 4 (ppko) 4 (CH 3 OH) 4 ] ( 1 ; ppkoH = phenyl 2-pyridyl ketoxime) was synthesized via a solvothermal route and characterized by X-ray diffraction, IR, EPR, ESI-MS and magnetic properties measurements. In 1 Mn 2+ ions are bridged with phenyl 2-pyridyl ketoxime ligands. Bromine atoms and methanol molecules are terminal ligands. A comparison is made to the reported analogues with different terminal ligands pattern.

The cyano-bridged 3D heteronuclear polymeric complex, [Cd(NH 3 )( μ -ampy)Ni( μ -CN) 4 ] n , ( 1 ) (ampy = 3-aminomethylpyridine), has been synthesized and characterized by FT-IR and Raman spectral, thermal and elemental analyses. The crystal structure of 1 has been determined by X-ray single crystal diffraction. The complex crystallizes in orthorhombic system with space group Pnma . In 1 , Ni(II) ion is five coordinated with square-pyramidal geometry defined by the four C atoms from the four symmetry related cyano ligands and one N atom from the ampy ligand. The Cd(II) ion adopts slightly distorted octahedral coordination geometry completed by the six N atoms from one ammine, one ampy and four cyano ligands. The [Ni(CN) 4 ] 2– anion is coordinated to the adjacent four Cd(II) ions to generate a Cd—Ni(CN) 4 2D undulate layer. The adjacent 2D layers are connected by the μ -ampy bridging ligands to form a 3D pillar-layered framework.

The existence of three types of salts of amino acid hexafluorosilicates 2 A + · SiF 6 2– , A 2+ · SiF 6 2– and 2(A ··· A + ) · SiF 6 2– , where A is an amino acid in zwitterionic state, A + is a singly charged cation, A 2+ is a doubly charged cation and (A ··· A + ) is a dimeric cation with a short hydrogen bond, have been established, in the literature (Ghazaryan, V. V.; Fleck, M.; Petrosyan, A. M.: Salts of amino acids with hexafluorosilicate anion. J. Cryst. Growth (2011), doi: 10.1016/j.jcysgro.2011.11.017). Here we report the investigation of hexafluorosilicates of α-alanine. Both L- and DL-alanine form salts according to the main 2 A + · SiF 6 2– type: 2L-Ala + · SiF 6 2– · 3 H 2 O and 2DL-Ala + · SiF 6 2– · 2 H 2 O. In addition we found that L-alanine forms a new A + · (A ··· A + ) · SiF 6 2– type of salt: L-Ala + · (L-Ala ··· L-Ala + ) · SiF 6 2– · H 2 O. Results of structural and vibrational spectroscopic studies are described and discussed.

The crystal structures of the 1 : 1 proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with the monocyclic heteroaromatic carboxylic acids, isonicotinic acid, picolinic acid, dipicolinic acid and pyrazine-2,3-dicarboxylic acid have been determined at 200 K and their hydrogen-bonding patterns examined. The compounds are respectively anhydrous 4-carbamoylpiperidinium pyridine-4-carboxylate ( 1 ), the partial hydrate 4-carbamoylpiperidinium pyridine-2-carboxylate 0.25 water ( 2 ), the solvate 4-carbamoylpiperidinium 6-carboxypyridine-2-carboxylate methanol monosolvate ( 3 ), and anhydrous 4-carbamoylpiperidinium 3-carboxypyrazine-2-carboxylate ( 4 ). In compounds 1 and 3 , hydrogen-bonding interactions give two-dimensional sheet structures which feature enlarged cyclic ring systems, while in compounds 2 and 4 , three-dimensional structures are found. The previously described cyclic R 2 2 (8) hydrogen-bonded amide-amide dimer is present in 2 and 3 . The hydrogen-bonding in 2 involves the partial-occupancy water molecule while the structure of 4 is based on inter-linked homomolecular hydrogen-bonded cation-cation and anion-anion associated chains comprising head-to-tail interactions. This work further demonstrates the utility of the isonipecotamide cation in the generation of chemically stable hydrogen-bonded systems, particularly with aromatic carboxylate anions, providing crystalline solids.