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Two-dimensional Layer Structure (two-dimensional + layer_structure)

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Chemistry100%

Selected Abstracts

Hierarchical Structures in Tin(II) Oxalates

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2008
Padmini Ramaswamy
Abstract Six new SnII oxalates exhibiting a hierarchy of structures have been prepared employing hydrothermal methods. The compounds I [C10N2H10][Sn(C2O4)2], II [C10N2H10][Sn2(C2O4)3], and III [C8N4H26][Sn(C2O4)2]2·2H2O possess zero-dimensional molecular structures; IV [C10N2H8]2[Sn(C2O4)]2 and V [C12N2H8][SnC2O4] have one-dimensional chain structures; and compound VI [C5N2H14]2[Sn4(C2O4)6]·7H2O has a two-dimensional layer structure. The SnII ions have 4- and 6-coordination with square-pyramidal or pentagonal-bipyramidal geometry, in which the lone pair of electrons also occupies one of the vertices. Weak intermolecular forces such as hydrogen-bond interactions, ,···, interactions, and lone-pair,, interactions have been observed and appear to lendstructural stability. Theoretical studies indicate that the ,···, interaction energy between the bound 1,10-phenanthroline molecules is of the order of 5,6 kcal,mol,1 in V. Natural bond orbital (NBO) analysis on two model compounds, II and IV, indicates reasonable lone-pair,, interactions. The close structural relationship between all the compounds indicates that a building-up process from the zero-dimensional monomer can be considered. The present structures provide opportunities for evaluating the structure-directing role of the lone pair of electrons of SnII.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

A Two-Dimensional, Hydrogen-Bond-Cross-Linked Molybdenum(VI) Network Polymer with Catalytic Activity

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2007
Yi Luan
Abstract The new hybrid inorganic,organic polymer [MoO2Cl2(H2O)2]·(H2dipy-pra)Cl2 (1), where dipy-pra = 1,3-bis(4-pyridyl)propane, has been synthesized and crystallographically characterized. MoO2Cl2(H2O)2 and the [H2dipy-pra]2+ cation are cross-linked by Mo,H2O···Cl and H2dipy-pra···Cl hydrogen bonds to form a two-dimensional layer structure. Complex 1 is an efficient catalyst, with H2O2 as the oxygen-source oxidant and NaHCO3 as the cocatalyst, in the epoxidation of olefinic compounds under ambient conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

EXAFS study of the Fex/ZrO2 composite nanomaterials obtained by sol,gel synthesis

JOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001
Vladimir Kriventsov
The local Zr and Fe arrangements in the nanocomposite system Fex/ZrO2 (x=0-0.2) obtained by sol-gel method were studied by EXAFS. The phase composition was found to vary significantly on iron loading. For the samples calcined at 500 or 600°C, at x,0.01, the formed ZrO2 is a mixture of monoclinic and tetragonal structures. Only tetragonal structure is revealed at x,0.05 with the exception of Fe0.2/ZrO2, calcined at 500°C, where new non-typically short Zr-Zr distances (3.29, 3.43Ĺ) were observed. At low iron loading (less than one monolayer) Fe3+ ions were found to localize within the pre-surface layers of ZrO2 nanoparticles showing property of isolated ions. For greater Fe loading, iron exhibits either two-dimensional layer structure or two-phase system. [source]

Constructing mixed-metal coordination polymers from copper(II),pyridinedicarboxylate metalloligands

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009
Guan-Hua Wang
In the mixed-metal complex catena -poly[bis[diaquasilver(I)] [bis[aquacopper(II)]-,3 -pyridine-2,5-dicarboxylato-2,:1:1,,5N,O2:O5:O5,O5, -,-pyridine-2,5-dicarboxylato-2:1,4N,O2:O5,O5, -disilver(I)-,3 -pyridine-2,5-dicarboxylato-1:1,:2,,,5O5,O5,:O5:N,O2 -,-pyridine-2,5-dicarboxylato-1,:2,,,,4O5,O5,:N,O2] hexahydrate], {[Ag(H2O)2][AgCu(C7H3NO4)2(H2O)]·3H2O}n, a square-pyramidal CuII center is coordinated by two N atoms and two O atoms from two pyridine-2,5-dicarboxylate (2,5-pydc) ligands and a water molecule, forming a [Cu(2,5-pydc)2(H2O)]2, metalloligand. One AgI center is coordinated by five O atoms from three 2,5-pydc ligands and, as a result, the [Cu(2,5-pydc)2(H2O)]2, metalloligands act as linkers in a unique ,3 -mode connecting AgI centers into a one-dimensional anionic double chain along the [101] direction. The other AgI center is coordinated by two water molecules, forming an [Ag(H2O)2]+ cation. Four adjacent AgI centers are associated by Ag...Ag interactions [3.126,(1) and 3.118,(1),Ĺ], producing a Z-shaped Ag4 unit along the [010] direction and connecting the anionic chains into a two-dimensional layer structure. This study offers information for engineering mixed-metal complexes based on copper(II),pyridinedicarboxylate metalloligands. [source]

Assembly of a two-dimensional layer structure with 1,4-bis(1H -benzimidazol-1-ylmethyl)benzene dihydrate via hydrogen bonds and ,,, interactions

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2008
Chuan-Mei Wu
In the title compound, C22H18N4·2H2O, the organic fragment lies across a centre of inversion in the P21/n space group. The water molecules form C(2)-type hydrogen-bonded chains which are linked to the 1,4-bis(1H -benzimidazol-1-ylmethyl)benzene molecules through O,H...N hydrogen bonds, forming sheets reinforced by ,,, stacking interactions between the aromatic rings within the layers. [source]

Poly­[trans -di­aqua­manganese(II)-,-(3-pyridine­carboxyl­ato- N:O)-,-(3-pyri­dinecarboxyl­ato- O:N)]

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2000
Xiang Hao
The title complex, [MnII(nic)2(H2O)2]n [nic is 3-pyridine­carboxyl­ate (also called nicotinate), C6H4NO2,], has a two-dimensional layer structure with the unique Mn atom on an inversion centre. In each layer, all nicotinate ligands are coordinated to Mn atoms in a bridging/bidentate mode, thus linking the {MnII(nic)2(H2O)2} monomeric units together to form a dative-bond-based layered polymer. The intra-layer hydrogen bonds involving all water mol­ecules and the carboxyl­ate groups may play an auxiliary part in stabilizing the layer. The layers are arranged in an ordered manner along the a axis through van der Waals forces so as to complete the solid-state structure of the crystal. [source]

Synthons and design in metal phosphates and oxalates with open architectures

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2001
C. N. R. Rao
We briefly describe the structures of open-framework metal phosphates with different dimensionalities, such as the one-dimensional linear-chain and ladder structures, two-dimensional layer structures and three-dimensional structures with channels. We demonstrate the role of the zero-dimensional four-membered ring monomer and of the one-dimensional ladder structure as the starting building units or synthons involved in the formation of the complex architectures. Thus, we show how the one-dimensional ladder structure transforms to two- and three-dimensional structures under mild conditions. The two-dimensional layer structures also transform to three-dimensional structures, while the zero-dimensional monomer transforms to layered and three-dimensional structures under ordinary reaction conditions. These transformations provide an insight into the possible pathways involved in the building up of the complex structures of metal phosphates. The isolation of amine phosphates during the hydrothermal synthesis of metal phosphates and also the facile reactions between amine phosphates and metal ions to yield a variety of open-framework materials have thrown light on the mechanism of formation and design of these structures. The existence of a hierarchy of open-framework metal oxalates and their ready formation by employing amine oxalates as intermediates provides additional support to the observations made earlier with regard to the phosphates. [source]