für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namen...

The cation Hgz2+ may be regarded as the simplest binuclear complex that contains a metal-metal single bond. This bond consists of an electron pair in a ubonding MO which is formed by the interaction of the 6s orbitals of both mercury ions [ 11. While in numerous studies it has been shown that metal-metal single bonds of binuclear transition metal complexes can be split homolytically by uu* exci...

Ikaite, CaC03 . 6 H20, is monoclinic, C2jc, with a = 8.792(2), b = 8.310(2), c = 11.021(2)A, P = 110.53(5)°, Z = 4. With 2205 independent reflectionstaken at 25°C of a naturally grown crystal specimen the structure was refined to a weighted Rw = 0.028. The C03 group is planar with C0 distances 1.279(2) and 1.290( 1) (2 x) A. The hydrogen bond network is determined. The optical behaviour is expl...

für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namen...

can (Tscyclam) has been used to reduce the coordination power of cyclam; the crystal structure of [Ni(Tscyclam)(H20)2]CIZ shows that the Ni-N (amide) distance is 0.3 A longer than the Ni-N (amine) distances [l]. On the other hand, the effects mentioned above may increase the acidity of the amidic hydrogen so that the amides could become anions in basic solution; the latter are good udonors. Thu...

X-ray crystallographic studies indicate that there are at least four site-specifically bound hydrated Mg 2 + ions, [Mg(H20)n] , in yeast tRNA. The size and the octahedral coordination geometry, rather than the charge, of [Mg(H2O)n] 2+ appear to be the primary reasons for the specificity of magnesium ions in site-binding and in the stabilization of the tertiary structure of tRNA.

The hydrolysis and condensation reactions of monomeric alkoxysilanes and organylalkoxysilanes utilized in sol-gel processing are reviewed. Both reactions occur by acid or base-catalyzed bimolecular displacement reactions. The acid-catalyzed mechanisms are preceded by protonation of OH or OR substituents attached to Si, whereas under basic conditions hydroxyl or silanolate anions attack Si direc...

Complexes of 1,2,4-triazole (trz) and of the 1,2,4triazolate ion (trz') have been described before. Most of the papers dealt with copper compounds, especially CuCl2(trz), CuCl(trz')(H20 ) 2 and Cu(trz')2 1_n. J a r v i s 12 determined the structure of CuCl2(trz). It is a polynuclear complex, the copper ions being bridged by two chloride ions and a 1,2-bicoordinating triazole ligand. The linear ...