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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretica chimica acta 91 (1995), S. 147-156 
    ISSN: 0040-5744
    Keywords: Key words: Density-functional theory ; Multiplets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  We investigate a simple generalization of the local-spin-density exchange-correlation approximation of density-functional theory from single to multi-determinantal states. The method is explicitly spin independent and trivially preserves multiplet spin degeneracies. Tests on multiplet splittings in a variety of low-lying configurations of first-row atoms and ions are presented.
    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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