Anomalous dehydration of 2-phenylindole-3-carboxamide to 2-phenylindole-3-carbonitrile by lithium aluminum hydride

Steric factors have been shown to be responsible for the anomalous dehydration of 2-phenylindole-3-carboxamide (1) to 2-phenylindole-3-carbonitrile (3) by lithium aluminum hydride. This steric effect was also reflected in the reactions of 2-phenylindole (4) and its derivatives.

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Anomale Dehydratisierung von 2-Phenylindol-3-carbonsäureamid zu 2-Phenyl-indol-3-carbonitril mit Lithiumaluminiumhydrid (Kurze Mitteilung)

Zusammenfassung Es wird gezeigt, daß für die anomale Dehydratisierung von 2-Phenylindol-3-carbonsäureamid (1) zum entsprechenden Nitril3 durch Lithiumaluminiumhydrid sterische Faktoren verantwortlich sind. Dieser sterische Effekt zeigt sich auch bei Reaktionen von 2-Phenylindol (4) und seiner Derivate.

     

Approaches to charge calculations in molecular mechanics

Alternative methods of estimating atomic charges in haloalkanes are presented, derived from quantum mechanical and classical treatments. A scheme based on a breakdown of the transmission of charge by polar atoms into one-bond, two-bond, and three-bond additive contributions is given, in which the one-bond effect is proportional to the difference in the electronegativities of the bonded atoms, and the two- and three-bond effects functions of the atomic electronegativity and polarizability. Suitable developments of the basic scheme, including an iterative self-consistent process, give calculated dipole moments for a variety of haloalkanes in good agreement with the observed values. The atomic charges obtained by this scheme are compared with other estimates of these charges. They are similar to those derived from a simple LCAO –MO scheme but differ from those obtained by population analysis of more refined quantum mechanical calculations.     

Complexes formed between nitrilotris(methylenephosphonic acid) and M(2+) transition metals: isostructural organic-inorganic hybrids

Nitrilotris(methylenephosphonic acid) (NTP, [N(CH(2)PO(3)H(2))(3)]) recently has been found to form three-dimensional porous structures with encapsulation of templates as well as layered and linear structures with template intercalation. It was, therefore, of interest to examine the type of organic-inorganic hybrids that would form with metal cations. Mn(II) was found to replace two of the six acid protons, while a third proton bonds to the nitrilo nitrogen, forming a zwitter ion. Two types of compounds were obtained. When the ratio of acid to Mn(II) was less than 10, a trihydrate, Mn[HN(CH(2)PO(3)H)(3)(H(2)O)(3)] (2) formed. Compound 2 is monoclinic P2(1)/c, with a = 9.283(2) A, b = 16.027(3) A, c = 9.7742(2) A, beta = 115.209(3) degrees, V = 1315.0(5) A(3), and Z = 4. The Mn atoms form zigzag chains bridged by two of the three phosphonate groups. The third phosphonate group is only involved in hydrogen bonding. The metal atoms are octahedrally coordinated with three of the sites occupied by water molecules. Adjacent chains are hydrogen-bonded to each other through POH and HN donors, and the additional participation of all the water hydrogens in H-bonding results in a corrugated sheet-like structure. Use of excess NTP at a ratio to metal of 10 to 1 yields an anhydrous compound Mn[HN(CH(2)PO(3)H)(3)] (1), P2(1)/n, a = 9.129(1) A, b = 8.408(1) A, c = 13.453(1) A, beta = 97.830(2) degrees, V = 1023.0(2) A(3), and Z = 4. Manganese is five coordinate forming a distorted square pyramid with oxygens from five different phosphonate groups. The sixth oxygen is 2.85 A from an adjacent Mn, preventing octahedral coordination. All the protonated atoms, three phosphonate oxygens and N, form moderately strong hydrogen bonds in a compact three-dimensional structure. The open-structured trihydrate forms a series of isostructural compounds with other divalent transition metal ions as well as with mixed-metal compositions. This is indicative that the hydrogen bonding controls the type of structure formed irrespective of the cation.     

Triangle-free graphs and completely positive matrices

Central European Journal of Operations Research - Completely positive matrices are matrices that can be decomposed as $$BB^T$$ , where B is an entrywise nonnegative matrix. These matrices have many...