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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 6 (1999), S. 243-254 
    ISSN: 1434-6079
    Keywords: PACS. 36.40.-c Atomic and molecular clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Characteristic properties as well as possible differences in bonding of small group 12 clusters ( , Cd, Hg; ) have been investigated by quantum chemical ab initio methods, i.e., relativistic large-core pseudopotentials, core-polarization potentials and coupled-cluster correlation treatments. A comparison of cohesive energies and spectroscopic properties like ionization potentials, electron affinities, and vibrational frequencies reveals a close similarity between the clusters of Cd and Hg. For Zn clusters we observed an exceptional increase in stability between and . In order to get a more qualitative picture of the covalent contributions to bonding we have calculated the electron localization function (ELF). The ELF analysis is in accordance with the calculated spectroscopic properties and shows predominant van der Waals interactions with weak covalent contributions for all the cluster sizes considered.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: [Disodium(2 +)][1,2-Diselena-diboranate(2 -)] ; [Tetraphenylphosphonium(1 +)][μ2-Selena-(diboranyl)boranate(1 -)] ; preparation ; SCF calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Vibrational Spectroscopic Investigation of [H3B—Se—Se—BH3]2- and [H3B-μ2-Se(B2H5)]- Crystal Structure and Theoretical Investigation of the Molecular Structure of [H3B-μ2-Se(B2H5)]-M2[H3B—Se—Se—BH3] 1 is produced by the reaction between elemental selenium and MBH4 (1 : 1) in triglyme (diglyme), under dehydrogenation. 1 reacts with an excess of B2H6 to give M[H3B-μ2-Se(B2H5)] 2 which is also formed in the reaction of THF · BH3 with 1. These reactions proceed under cleavage of the Se—Se bond and hydrogen evolution. [(C6H5)4]Br reacts with Na · 2 to form [(C6H5)4P] · 2 which crystallizes in the tetragonal space group I4 (Nr. 82). An X-ray structure determination failed because of disordering of the cation and anion. 11B, 77Se NMR shifts and 1J(11B1H) coupling constants as well as IR- and Raman spectroscopic investigations convey further structural information. Structural data of 2 have been calculated by SCF methods. The anion of 2 may be viewed either as an adduct of Se with B3H8-, or as a bridge substituted selena derivative of B2H6.
    Notes: Bei der Reaktion zwischen elementarem Selen und MBH4 (1 : 1) (M = Na, Li) in Triglyme (Diglyme) entsteht unter Wasserstoffabspaltung M2[H3B—Se—Se—BH3] 1. Bei der Behandlung von 1 mit überschüssigem B2H6 oder THF · BH3 wird die Se—Se-Bindung gespalten und es entsteht unter erneuter Wasserstoffabspaltung M[H3B-μ2-Se(B2H5)] 2. Aus Na · 2 und [(C6H5)4P]Br entsteht [(C6H5)4P] · 2, welches tetragonal in der Raumgruppe I4 (Nr. 82) kristallisiert. Kation und Anion sind im Kristall fehlgeordnet. Strukturinformationen konnten aus den 11B-, 77Se- und 1J(11B1H)-Daten einerseits und den IR- und Raman-spektroskopischen Untersuchungen andererseits erhalten werden. Aus SCF-Rechnungen erhielten wir die Strukturparameter für das Anion 2. 2 kann sowohl als Addukt von Se an B3H8- als auch als brückensubstituiertes Selena-Derivat des B2H6 aufgefaßt werden.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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