Polar intermetallic compounds as catalysts for hydrogenation reactions: Synthesis, structures, bonding, and catalytic properties of Ca 1-xSrxNi4Sn2 (#=0.0, 0.5, 1.0) and catalytic properties of Ni3Sn and Ni3Sn2

Viktor Hlukhyy, Fabian Raif, Peter Claus, Thomas F. Fässler

Publikation: Beitrag in FachzeitschriftArtikelBegutachtung

20 Zitate (Scopus)

Abstract

The potential of polar intermetallic compounds to catalyze hydrogenation reactions was evaluated. The novel compounds CaNi4Sn2, SrNi4Sn2, and Ca0.5Sr0.5Ni 4Sn2 were tested as unsupported alloys in the liquid-phase hydrogenation of citral. Depending on the reaction conditions, conversions of up to 21.0% (253 K and 9.0 MPa hydrogen pressure) were reached. The binary compounds Ni3Sn and Ni3Sn2 were also tested in citral hydrogenation under the same conditions. These materials gave conversions of up to 37.5%. The product mixtures contained mainly geraniol, nerol, citronellal, and citronellol. The isotypic stannides CaNi4Sn 2, Ca0.5Sr0.5Ni4Sn2, and SrNi4Sn2 were obtained by melting mixtures of the elements in an arc-furnace under an argon atmosphere. Single crystals were synthesized in tantalum ampoules using special temperature modes. The novel structures were established by single-crystal X-ray diffraction. They crystallize in the tetragonal space group I4/mcm with parameters: a = 7.6991(7), c = 7.8150(8)Å, wR2 = 0.034, 162 F2 values, 14 variable parameters for CaNi4Sn2; a = 7.7936(2), c = 7.7816(3)Å, wR2 = 0.052, 193 F2 values, 15 variable parameters for Ca 0.5Sr0.5Ni4Sn2; and a = 7.8916(4), c = 7.7485(5) Å, wR2 = 0.071, 208 F2 values, 14 variable parameters for SrNi4Sn2. The Ca1-xSr xNi4Sn2 (x = 0.0, 0.5, 1.0) structures can be represented as a stuffed variant of the CuAl2 type by the formal insertion of one-dimensional infinite Ni-cluster chains [Ni4] into the Ca(Sr)Sn2 substructure. The Ni and Sn atoms form a three-dimensional infinite [Ni4Sn2] network in which the Ca or Sr atoms fill distorted octagonal channels. The densities of states obtained from TB-LMTO-ASA calculations show metallic character for both compounds.

OriginalspracheEnglisch
Seiten (von - bis)3737-3744
Seitenumfang8
FachzeitschriftChemistry - A European Journal
Jahrgang14
Ausgabenummer12
DOIs
PublikationsstatusVeröffentlicht - 18 Apr. 2008

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