Oxidative coupling of silylated nonagermanide clusters

Abstract

Polyhedral main group element clusters of tetrel elements are discussed as suitable building units to form atom-precise nano-structures. Herein we report the oxidative coupling of two [Ge9{Si(TMS)3}2]2– clusters (TMS: trimethylsilyl)...

Oxidation of [Ge9{Si(SiMe3)3}3]− with LnI3 (Ln = Eu, Sm, Yb): Isomerism of Metalloid Germanium Clusters

“…For example, mild oxidation of the Zintl anion Ge 9 4– generates the corresponding oligo- or polymers . Very recently, Fässler et al have reported the oxidative coupling of disilylated germanium cluster [Ge 9 (Hyp) 2 ] 2– (Hyp = Si­(SiMe 3 ) 3 ) affording a dimeric cluster [Ge 18 (Hyp) 4 ] 2– , which was identified by mass spectrometry . In our group, the metalloid germanium cluster [Ge 9 (Hyp) 3 ] − available in high yield by the reaction of Ge 9 4– with ClSi­(SiMe 3 ) 3 has been oxidized with FeCl 2 in the presence of diphenylphosphinoethane (dppe), resulting in a neutral Ge 18 (Hyp) 6 cluster A and the reduced Fe­(I) salt, [Fe­(dppe)]­[Ge 9 (Hyp) 3 ] .…”

Oxidative Coupling of [Ge9(Si(SiMe3)3)2]2– with f Elements

“…The same bonds in the naked cluster [Ge 9 −Ge 9 ] 6− are between 257 and 259 pm, 1 while those in the copper-capped silylated cluster are between 252 and 254 pm. 9 This elongation in the naked cluster can be explained by the larger amount of space that the nonbonding electrons at the capping atom need, compared to the space needed by the exobond to the hypersilyl ligand. This can also be observed at the open square on the opposite side of the cluster, which has one exobond between the Ge 9 moieties and in the case of 1 and 2 another exobond to the second ligand.…”

“…Here, the dimer was structurally characterized as the [NHC iPr Cu] + adduct {NHC iPr Cu[Ge 9 (Hyp) 2 ]} 2 [NHC iPr = 1,3-di(isopropyl)imidazolylidine], while a dimeric anion [Ge 18 (Hyp) 4 ] 2− was only postulated on the basis of mass spectra. 9 The oxidizing agent in fact turned out to be very doubtful, since the reaction was carried out in the presence of Cy 2 BCl (Cy = cyclohexyl) and appeared to be mediated by trace amounts of oxygen. A byproduct, Cy 2 B−O−BCy 2 , was isolated instead of a reducing product.…”

“…This bond length in both clusters agrees well with the sum of the covalent radii of Ge (242 pm) 13 and is only slightly larger than the Ge−Ge distance in α-Ge (244.5 pm). 14 Compared to the linking Ge−Ge bonds within [Ge 9 −Ge 9 ] 6− (248.8 pm) 1 and the [(NHC)-CuGe 9 (Hyp) 2 ] 2 2− (242.6 pm), 9 the Ge−Ge exobonds in 1 and 2 are between those lengths.…”

“…The NHC−Cu derivative of the clusters shows an angle of 75.4°between those faces. 9 We can attribute some of those differences to the presence of the hypersilyl ligands and maybe the counterion, as the pocket that is created by the open faces in 1 is occupied by Yb(thf) 6 ; it is also occupied by one K(2.2.2-crypt) moiety in 2. The other K(2.2.2-crypt) is located alongside the cluster (see Supporting Information).…”