Potassium carbamoyldi­cyano­methanide

The crystal structure of the title compound, K[(CN)₂CC(O)NH₂)] or K⁺·C₄H₂N₃O⁻, conventionally abbreviated as Kcdm, where cdm is carbamoyldi­cyano­methanide, is described. The bond lengths and angles of the cdm cation are comparable to those reported previously for [M(cdm)₂(H₂O)₄]·2H₂O (M = Ni, Mn and Co). The K atoms are coordinated to four nitrile N atoms and two carbonyl O atoms in a distorted trigonal prismatic fashion, with two further N atoms semicoordinated through the centers of two prism side faces. This coordination leads to the formation of mixed anion–cation sheets parallel to the ab plane, which are joined together via hydrogen‐bonding interactions. The cdm anion is potentially useful for the formation of transition metal coordination polymers, in which magnetic superexchange could occur through a bidentate cdm bridge. Kcdm provides a model compound by which the molecular geometry of the cdm anion can be analyzed.     

Extendability of Large-Scale Lipschitz Maps

Let be metric spaces, a subset of , and a large-scale lipschitz map. It is shown that possesses a large-scale lipschitz extension (with possibly larger constants) if is a Gromov hyperbolic geodesic space or the cartesian product of finitely many such spaces. No extension exists, in general, if is an infinite-dimensional Hilbert space. A necessary and sufficient condition for the extendability of a lipschitz map is given in the case when is separable and is a proper, convex geodesic space.

     

Photocyclisierung von 1-[3-(Chloracetylamino)propyl]-3-methylindol. 12. Mitteilung über synthetische Indol-Verbindungen

Photochemical cyclization of 1-[3-(chloroacetylamino)propyl]-3-methyl-indole . Photochemical cyclization of 1-[3-(chloroacetylamino)propyl]-3-methyl-indole involving loss of HCl leads to the three isomers 2, 3 and 4 , the structures of which have been determined by physical and chemical methods.     

An Investigation of the Tea Aroma. Part I. New volatile black tea constituents

A total of 68 constitutents, mainly aldehydes, ketones and esters, have been identified for the first time in a black tea aroma concentrate using coupled gas-chromatography/mass spectrometry.     

Determination of the Relative Configurations in the Side Chains of the Antibiotics Hedamycin and Pluramycin A; Synthesis and NMR. Data of Suitable Model Compounds

Several diepoxyhexanoates and epoxyhexenoates were prepared by epoxidation of methyl 2-methyl-2,4-hexadienoate or by Darzens condensation. Their ¹ H- and ¹³C-NMR. spectra were measured and assigned. Comparison of these data with the spectra of the antibiotics hedamycin ( 1 ) and pluramycin A ( 2 ) allowed the determi-nation of the relative configurations in the side chains of these antibiotics. They were found to be (14R*,16S*,17R*,18S*) for hedamycin ( 1 ) and (14R*,16S*,17Z) for pluramycin A ( 2 ).     

John Napiers Trigonometrie – ein Blick zurück

Zusammenfassung  Dieser Artikel gibt einen überblick über Napiers Beitr?ge zur sph?rischen Trigonometrie, wobei die dafür notwendigen sachlichen und historischen Grundlagen weitgehend bereitgestellt werden. Da diese Beitr?ge in der Literatur trotz ihrer erheblichen Bedeutung ganz im Schatten von Napiers Logarithmen stehen, erscheint eine solche Zusammenschau gerechtfertigt. Auch kommen einige neue oder kaum bekannte Einzelheiten zur Sprache. Mathematics subject classification (2000)  01A45 · 51-03     

A nondisplaceable Lagrangian torus in T*S2

We show that the Lagrangian torus in the cotangent bundles of the 2‐sphere obtained by applying the geodesic flow to the unit circle in a fiber is not displaceable by computing its Lagrangian Floer homology. The computation is based on a symmetry argument. © 2007 Wiley Periodicals, Inc.