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Ammine Ligands (ammine + ligand)
Selected AbstractsAmmine(2,2,-bipyridine-,2N,N,)silver(I) nitrate: a dimer formed by ,,, stacking and ligand-unsupported Ag...Ag interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010Di Sun Reaction of AgNO3 and 2,2,-bipyridine (bipy) under ultrasonic treatment gave the title compound, [Ag(C10H8N2)(NH3)]NO3. The crystal structure consists of dimers formed by two symmetry-related AgI,bipy monomers connected through intra-dimer ,,, stacking and ligand-unsupported Ag...Ag interactions. A crystallographic C2 axis passes through the mid-point of and is perpendicular to the Ag...Agi(,x + 1, y, ,z + ) axis. In addition, each AgI cation is coordinated by one chelating bipy ligand and one ammine ligand, giving a trigonal coordination environment capped by the symmetry-equivalent Ag atom. Molecules are assembled by Ag...Ag, ,,,, hydrogen-bond (N,H...O and C,H...O) and weak Ag..., interactions into a three-dimensional framework. Comparing the products synthesized under different mechanical treatments, we found that reaction conditions have a significant influence on the resulting structures. The luminescence properties of the title compound are also discussed. [source] The neutral cluster amminehexa-,2 -chlorido-,4 -oxido-tris(1,4,6-triazabicyclo[3.3.0]oct-4-ene)tetracopper(II)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2009Gina M. Chiarella The title compound, [Cu4Cl6O(C5H9N3)3(NH3)], is a neutral conformationally chiral cluster which crystallizes under the conditions described in this paper as a racemic conglomerate. It contains four CuII atoms in a tetrahedral coordination with a central O atom lying on a crystallographic threefold axis. Six chloride anions bridge the four CuII atoms. Three CuII atoms are bound by an N atom of a monodentate 1,4,6-triazabicyclo[3.3.0]oct-4-ene (Htbo) ligand and the remaining CuII atom is bound by a terminal ammine ligand. The geometry at each copper center is trigonal bipyramidal, produced by the bound N atom of Htbo or ammonia, the O atom in the axial position, and three chloride ions in the equatorial plane. The chloride anions form an octahedron about the oxygen center. The copper,ammonia bond lies along the crystallographic threefold axis, along which the molecules are packed in a polar head-to-tail fashion. [source] Ligand Influence on Metathesis Activity of Ruthenium Carbene Catalysts: A DFT StudyADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2007Bernd Abstract A survey of the concept of active and inactive ligand conformations in ruthenium alkene carbene complexes of the Grubbs catalyst type is presented. This concept is extended to a variety of anionic ligand atoms. Density functional theory calculations at the B3LYP/LACV3P**+//B3LYP/LACVP* level of theory were performed on the precatalyst, 14 valence-electron intermediate, alkene carbene conformers and ruthena(IV)cyclobutane model intermediates for several ligands, such as methoxide, methanethiolate, fluoride, mesylate, water, and ammonia. The rule of the superiority of metathesis catalysts with small and electron-withdrawing halogens does not apply to fluoride ligands. Alkoxides and thiolates also destabilize active carbene conformations, while mesylate ligands lead to a balanced energetic relation of active and inactive carbene orientations. Cationic ruthenium carbene species with aqua or ammine ligands are limited by unfavored ligand dissociation to 14 valence-electron intermediates. A guideline for the design of novel ligand systems for ruthenium carbene complexes as metathesis catalysts is proposed. [source] Diamminesilver(I) bis(2-amino-5-nitrobenzoato-,2O1,O1,)silver(I): a two-dimensional supramolecular sheet with a short intersheet distance containing a rare four-coordinate planar silver(I) centreACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Di Sun The asymmetric unit of the title compound, [Ag(NH3)2][Ag(C7H5N2O4)2], comprises half an [Ag(NH3)2]+ cation and half an [Ag(anbz)2], anion (anbz is 2-amino-5-nitrobenzoate). Both AgI ions are located on inversion centres. The cation has a linear coordination geometry with two symmetry-related ammine ligands. The AgI cation in the anionic part shows a rare four-coordinate planar geometry completed by two chelating symmetry-related anbz ligands. Intra- and intermolecular N,H...O hydrogen bonds create a slightly undulating two-dimensional supramolecular sheet. Adjacent sheets are only ca 3.3,Å apart. Ag...O, Ag...N and ,,, stacking interactions consolidate the packing of the molecules in the solid state. [source] Loss of Ammine from Platinum(II) Complexes: Implications for Cisplatin Inactivation, Storage, and Resistance,CHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2005Justin Kai-Chi Lau Abstract Potential consequences of the binding of the anticancer drug cisplatin to various biomolecules in the cell have been investigated by using a combined density functional theory and continuum dielectric model approach. Since the ammine ligands remain coordinated at the metal upon formation of the most frequent DNA adducts, whereas they were found to be displaced from the metal upon formation of drug metabolites, we have analyzed the factors governing ammine loss from platinum(II) complexes as a possible pathway of cisplatin inactivation. The calculations systematically show the effect of 1) the trans ligand, 2) the charge of complex, 3) the nucleophile, and 4) the environment on the thermodynamic instability and kinetic lability of the platinum,ammine bonds. After initial binding of cisplatin hydrolysis products to thioethers or thiols, loss of the ammine trans to this sulfur ligand rather than replacement of the sulfur ligand itself by other nucleophiles like guanine-N7 is predicted to be the predominant reaction. The results of this study contribute to an understanding of the modes of cisplatin inactivation prior to DNA binding, for example, by elevated glutathione levels in cisplatin-resistant cancer cells. [source] | ||||||||||