Reported is the first rational synthesis of a trisubstituted deltahedral Zintl ion, [Ge9{Si(SiMe3)3}3]− in this case, by the addition of the three substituents in a reaction of the parent naked deltahedral Zintl ion Ge9 4– with {(Me3Si)3Si}Cl. The new species were crystallized and structurally characterized in [K(2,2,2-crypt)]2[Ge9{Si(SiMe3)3}3] (monoclinic, P21/c, a = 26.497(3) Å, b = 24.090(2) Å, c = 29.268(3) Å, β = 113.888(2)°, V = 17082(3) Å3, Z = 8, R1/wR2 = 0.0436/0.0812 for the observed data and 0.1023/0.1010 for all data).

Reported are the rational synthesis, structures, and solution dynamics of three tetrasubstituted and neutral Ge9-based deltahedral clusters [Ge9R3R'](0), where R = Si(SiMe3)3 and R' = Et (1), Sn(n)Bu3 (2), or Tl (3). The first step of the synthesis is a reaction of an acetonitrile suspension of the intermetallic precursor compound K4Ge9 with {Si(SiMe3)3}Cl which produces the trisubstituted monoanions [Ge9{Si(SiMe3)3}](-). A benzene suspension of the latter is then reacted with Sn(n)Bu3Cl or TlCp to produce 2 and 3, respectively, while the same acetonitrile solution is reacted with EtBr in order to produce 1. All three structures can be viewed as tricapped trigonal prisms of Ge9 with the three "hypersilyl" substituents, Si(SiMe3)3, exo-bonded to the capping atoms. The fourth substituent in 1, the ethyl group, is exo-bonded to one of the six available Ge atoms with the Ge-C bond positioned radially to the Ge9 core. In the case of 2, on the other hand, the tin fragment is found above one of the triangular bases of the prism interacting with one or more Ge atoms in three crystallographically different molecules in the structure. Lastly, the Tl atom in the structure of 3 is found capping a pseudosquare face between two hypersilyl substituents. NMR spectroscopy indicates that all three compounds are dynamic at room temperature. Variable-temperature studies suggest that the process in 1 and 2 is intramolecular while the process in 3 involves dissociation of the Tl(+) ion from the molecule followed by association at the same or another equivalent pseudosquare face of the molecule. Thus, the latter compound may be considered to a large extent to be ionic as it is made of a thallium cation and a trisubstituted cluster anion.

The recently developed approach for the rational functionalization of deltahedral nona-germanium clusters Ge9(4-) with three substituents to form Ge9R3(-) (R = Si(SiMe3)3) in large amounts has made the latter a convenient starting material for further reactivity studies. Reported here are the synthesis, structures, and solution studies of two compounds where Ge9R3(-) are used as ligands to transition metals, [(Ge9R3)Cu(I)(Ge9R3)Cu(I)PPh3] (1) and [(Ge9R3)Pd(0)(Ge9R3)](2-) (2). The former adds to the families of anionic [(Ge9R3)M(I)(Ge9R3)](-) (M(I) = Cu, Ag, and Au) as a neutral member and of the neutral [(Ge9R3)M(II)(Ge9R3)] (M(II) = Zn, Cd, and Hg), while the latter represents the first compound involving a metal from group 10.

The title compound, which has a ten-atom deltahedral cluster core of Ge9 Pd, was synthesized through insertion of Pd(PPh3 ) into the tetrasubstituted nona-germanium cluster [(Me3 Si)Si]3 EtGe9 through a reaction of the latter with Pd(PPh3 )4 . This first reaction of neutral tetrasubstituted nine-atom clusters shows that they retain reactivity despite their neutral charge. The Ge9 Pd core is the first that incorporates a 5-connected transition metal other than from Group VI, a noble metal in this case. Single-crystal X-ray diffraction shows that the ten-atom core is a closo-cluster with the expected shape of a bicapped square antiprism. (1) H and (13) C NMR spectroscopy show that, in contrast to the parent tetra-substituted [(Me3 Si)Si]3 EtGe9 , the new compound does not exhibit dynamics. Relativistic DFT calculations are used to explain the differences.

Reaching neutral territory: The title compound, the first tetrasubstituted deltahedral Zintl cluster, is no longer an ion (see picture; Ge green, Si purple, Sn blue). It is a neutral molecule formed by a reaction of the trisilylated anion with Ph(3) SnCl.