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81.
Joy Chakraborty Brajagopal Samanta Andrei S. Batsanov Joan Ribas M. Salah El Fallah Samiran Mitra 《Structural chemistry》2006,17(4):401-407
A ligand–metal–ligand type co-ordination polymer [Ni (C6H12N4)(NCS)2(H2O)2]
n
has been synthesised under controlled hydrothermal conditions. Here 1,3,5,7-tetraazatricyclo[3.3.1]decane [or hexamethylenetetramine (hmt)] has been used as a μ-(N,N′) bidentate spacer molecule. The prepared polymeric complex has been characterised by elemental and spectral analyses. The structure has been confirmed by a single crystal X-ray diffraction study. Magneto-structural correlation has been drawn from cryomagnetic susceptibility measurements (2–300 K) which unequivocally reflects very weak magnetic spin interactions among the long distant octahedral Ni(II) metal centres mediated by hmt and weak hydrogen bonding interactions between the adjacent zigzag one-dimensional polymeric chains carrying into a two-dimensional infinite polymeric framework. 相似文献
82.
Anamika Das Christoph Marschner Joan Cano Judith Baumgartner Joan Ribas M. Salah El Fallah Samiran Mitra 《Polyhedron》2009
Two new dicyanamido-bridged di- and polynuclear complexes of Co(II), [Co(dca)(tptz)(H2O)]2·2(ClO4) (1) and [Co(dca)2(imz)2]n (2) [dca, dicyanamide; tptz, 2,4,6-tris(2-pyridyl)1,3,5-triazine; and imz, imidazole] have been synthesized and characterized structurally, as well as magnetically. The X-ray single crystal structure determination of complex 1 shows that two symmetry related octahedral Co(II) ions are separated by dca ligand and other coordination sites are satisfied by tptz and aquo ligands. Each dinuclear unit is associated with each other by intramolecular hydrogen bonding interactions, giving rise to a 1D chain structure. On the other hand complex 2 is a 1D coordination polymer having [Co(II)(imz)2] units connected by double bridging dca ligands. These 1D chains interact through face-to-face π–π stacking interactions of the imz rings extending the dimensionality to a 2D supramolecular network. The variable temperature (300–2 K) magnetic measurements of both compounds reveal that dicyanamide exhibits a weak antiferromagnetic interaction between the metal centers. 相似文献
83.
Mohamed Salah K. Youssef Ragaa A. Ahmed Mohamed S. Abbady Shawkat A. Abdel-Mohsen Ahmed A. Omar 《Monatshefte für Chemie / Chemical Monthly》2008,45(8):553-559
4-(2-Aminothiazol-4-yl)-3-methyl-5-oxo-1-phenyl-2-pyrazoline was synthesized via the reaction of 4-bromoacetyl-3-methyl-5-oxo-1-phenyl-2-pyrazoline with thiourea [7] and was transformed to related fused
heterocyclic systems. The antifungal and antibacterial studies revealed in some cases excellent biocidal properties. 相似文献
84.
85.
86.
87.
Salah Haggag 《General Relativity and Gravitation》1999,31(8):1169-1186
Kramer's formulation of Einstein's fieldequations for static perfect fluid cylinders isconsidered. Three approaches are followed in seekingsolutions of Kramer's equations. First, a particularintegral is found which reproduces a previously knownclass of four solutions. Second, a fairly general ansatzis suggested, whereby a class of six new solutions isderived. Finally, the problem for an incompressible perfect fluid, with constant energy density, isreduced to a single second order equation. All solutionsare regular everywhere. Constraints are imposed on thesolutions parameters such that energy conditions are satisfied and hence the solutions arephysically reasonable. 相似文献
88.
89.
A spectrophotometric and a photometric titration method in a two-phase system for the determination of gold with ferroin is reported. Both methods are rapid and reproducible with an accuracy of ±1%. In the spectrophotometric determination Co2+, Cu2+, Ni2+ , Fe3+, Zn2+, Mn2+ and Cr3+ do not interfere with the determination of gold and Pt4+, Pd2+, Hg2+, Ir4+ and Os4+ can be tolerated up to a ratio of 1:1. The titrations can also be carried out in the presence of a number of diverse ions, e.g. Ni2+, Cu2+, Co2+, Fe3+, Zn2+, Cr3+, Mn2+, without interference; the platinum metals and Hg2+ cause interference but, by the use of the spectrophotometric procedure, this can be reduced. 相似文献
90.
R. Ben Hassen A. Ben Salah A. Kallel A. Daoud J. Jaud 《Journal of chemical crystallography》2002,32(11):427-430
CH3NH3CdBr3 crystallizes in the space group Ccm21, a = 13.693(1) Å, b = 7.906(1) Å, c = 6.886(1) Å, V = 745.46(15) Å3, Z = 4, D
x
= 3.42 Mg m–3. The structure of the title compound is one-dimensional consisting of infinite chains made of face sharing CdBr6 octahedra. The methylammonium groups are situated in the space between chains. The cations and anions are joined by hydrogen bonding. 相似文献