Triclinic Crystal System (triclinic + crystal_system)

Distribution by Scientific Domains


Selected Abstracts


Highly Symmetrical Tetranuclear Cluster Complexes Supported by p - tert -Butylsulfonylcalix[4]arene as a Cluster-Forming Ligand

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006
Takashi Kajiwara
Abstract Square-planar tetranuclear clusters [M4(L)(AcO)4(,4 -OH)], (M = MnII, CoII, and NiII) are synthesized using tetra-anionic p - tert -butylsulfonylcalix[4]arene (L4,) as a cluster-forming ligand. Three complexes are crystallographically isostructural, being crystallized in the triclinic crystal system with space group P. The calix[4]arene acts as a tetrakis fac -tridentate ligand through four phenoxo and four sulfonyl oxygen atoms to form square arrangement of four metal ions, which are further bridged by four chelating acetate ions and one hydroxo ion in a ,4 manner to complete the hexacoordination of each metal center. Although the whole molecule of each complex is crystallographically independent, the molecule is highly symmetrical with a pseudo-four-fold axis lying on the ,4 -OH, group. The tetranuclear clusters are stable enough to maintain the core structures even in highly dilute solution (,10 ,M), which was confirmed by mass spectroscopic study, however, bridging acetates were easily exchanged by other carboxylate chelates to form derivatives such as [M4(L)(BzO)4(OH)],. Metal,metal interactions were investigated by means of magnetic susceptibility, and it was revealed that both ferro- and antiferromagnetic interactions occur in the NiII complex depending on the bridging angles of Ni,O,Ni. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]


Two hydrates of 6-methoxy­purine

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2004
Natalya Fridman
6-Methoxy­purine crystallizes from N,N -methyl­form­amide as the hemihydrate, C6H6N4O·0.5H2O, and from water as the trihydrate, C6H6N4O·3H2O. Both forms crystallize in the triclinic crystal system. Upon heating the trihydrate, mol­ecules of water are liberated successively; the hemihydrate is formed at 383,K. In the hemihydrate, the H atom on the imidazole N atom is disordered between the two N atoms. The water mol­ecule in the hemihydrate and the H atoms of a water mol­ecule in the trihydrate are also disordered. In the hemihydrate, the organic moieties are connected by N,H,N hydrogen bonds, while they are connected via water mol­ecules in the trihydrate. [source]


Inclusion Behavior of ,-Cyclodextrin with Bipyridine Molecules: Factors Governing Host-Guest Inclusion Geometries

CHEMISTRY - AN ASIAN JOURNAL, Issue 3 2009
Yan-Li Zhao Dr.
Abstract Guest Effect: The differences of nitrogen atom positions and the bridge bonds linked to two pyridine rings of some bipyridine guests can significantly affect the binding abilities and inclusion geometries of ,-cyclodextrin with the guests in both the solution and solid states. The 1:1 complexation of ,-cyclodextrin (,-CD) with structurally similar bipyridine guests which lead to the formation of six inclusion complexes (1,6) of ,-CD with 4,4,-vinylenedipyridine, 2,2,-vinylenedipyridine, 1-(2-pyridyl)-2-(4-pyridyl)ethylene, 4,4,-ethylene-dipyridine, 4,4,-dithiodipyridine, and 2,2,-dithiodipyridine has been investigated comprehensively by X-ray crystallography in the solid state and by 1H,NMR spectroscopy and microcalorimetric titration in aqueous solution. The complex formation constants (KS) for the stoichiometric 1:1 host,guest inclusion complexation of ,-CD with the bipyridine derivatives were determined in aqueous solution by microcalorimetry and the host,guest inclusion geometries of the complexes were deduced from 1H ROESY NMR spectroscopy. It transpires that the guest bipyridine molecules are included in the ,-CD cavity with a range of different inclusion geometries. In the solid state, the crystal superstructures for the ,-CD complexes 1, 4, and 5 are characterized by the triclinic crystal system (space group P1) commensurate with AAAA type supramolecular aggregation. By contrast, the ,-CD complexes 2, 3, and 6 display either monoclinic (space group P21) or orthorhombic (space group C2221) crystal systems, characteristic of ABAB type supramolecular aggregation. The results demonstrate that the relative locations of the nitrogen atom positions and the bridge-bond links between the two pyridine rings in these bipyridine guests, not only lead to distinct crystal systems and space groups, but also to different binding geometries and thermodynamical parameters on complexation of the bipyridines with ,-CD. The knowledge obtained from this research improves our understanding of the molecular recognition and self-assembly processes exhibited by ,-CD, both in the solid state and in aqueous solution. [source]


Deposition of crystalline copper films from tetranuclear copper (II) complexes without application of reducing atmosphere

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2010
Muhammad Shahid
Abstract Crystalline copper films were deposited by aerosol-assisted chemical vapor deposition (AACVD) in the absence of hydrogen from two newly synthesized complexes [Cu(deae)(TFA)]4·1.25THF (1) and [Cu4(OAc)6(bdmap)2(H2O)2]·4H2O (2) [deae = N, N -diethylaminoethanolate, TFA = trifloroacetate, OAc = acetate and bdmap = 1,3-bis(dimethylamino)-2-propanolato]. These precursors were prepared in high yield using mixed ligands and crystallized in tetragonal and triclinic crystal systems with space groups 141/a and P , 1. Complexes 1 and 2 thermally decomposed at 290 and 250 °C, respectively, to yield copper films which were characterized by SEM/EDX for their morphology and composition and PXRD for their crystallinity and phase. These films have smooth morphologies with particle sizes within the range of 0.3,0.6 µm and may find applications in fabrication of ultralarge-scale integrated circuits. Copyright © 2010 John Wiley & Sons, Ltd. [source]