title: [Ga18(SitBu3)8] and [Ga22(SitBu3)8]--syntheses and structural characterization of novel gallium cluster compounds.
abstract: The novel neutral gallium cluster compounds [Ga18R*8] (1) and [Ga22R*8] (2) are obtained by warming up a metastable solution of gallium(I) bromide in THF/C6H5CH3 after addition of equimolar amounts of supersilyl sodium NaR* from -78 degrees C to room temperature (R* = SitBu3 = supersilyl). From X-ray structure analyses, the observed arrangements of the 18 and 22 Ga atoms in 1 and 2, respectively, are comparable with an 18 atom section of the beta-Ga modification, or show at least some kind of relationship to a 22 atom section of the Ga-III modification. This allows a description of both the clusters as metalloid. The topology of the atoms in 2 is also well explained by the Wade-Mingos rules as an eightfold capped closo-Ga14 cluster, whereby the Ga atoms of Ga14 occupy the center and the corners of a cuboctahedron with one Ga3 face replaced by a Ga4 face. Some concepts are presented about the formation mechanism, the cluster growth, and the metalloid character of the two Ga cluster compounds.
authors.affiliation: Institut für Anorganische Chemie der Universität Karlsruhe, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Donchev
authors.forename: A
authors.initials: A
authors.lastname: Schnepf
authors.forename: G
authors.initials: G
authors.lastname: Stösser
authors.forename: E
authors.initials: E
authors.lastname: Baum
authors.forename: H
authors.initials: H
authors.lastname: Schnöckel
authors.forename: T
authors.initials: T
authors.lastname: Blank
authors.forename: N
authors.initials: N
authors.lastname: Wiberg