Challenges in chemical synthesis at the border of solution-based and solid-state chemistry—Synthesis and structure of [CH3CH2Ge9{Si(SiMe3)3}]2−

Abstract

Polyanionic [Ge 9 ] 4– clusters are accessible in good yields by a solid-state reaction of the elements Ge and K. The nine-atom deltahedral germanium clusters are transformed to silylated species, which in a subsequent reaction allow for addition of an organic moiety. We present a synthetic method for a stepwise ligand exchange reaction at a Zintl ion. Herein, we functionalized the [Ge 9 {Si(SiMe 3 ) 3 } 2 ] 2− cluster with an ethyl group by a reaction with bromoethane. The obtained anion [CH 3 CH 2 Ge 9 {Si(SiMe 3 ) 3 } 2 ] − was characterized by NMR spectroscopy and mass spectrometry. After addition of 2,2,2-crypt an abstraction of one silyl ligand was observed resulting in the crystallization of [K(2,2,2-crypt)] 2 [CH 3 CH 2 Ge 9 {Si(SiMe 3 ) 3 }] representing the first monosilylated Ge 9 Zintl cluster, which carries an additional ethyl group. The latter compound was characterized by single crystal X-ray crystallography, NMR spectroscopy, and elemental analysis.