Acylation of Homoatomic Ge9 Cages and Subsequent Decarbonylation.

The direct acylation of Ge9 Zintl clusters by the reaction of K[Ge9 {Si(SiMe3 )3 }3 ] with acyl chlorides in hexane or toluene solutions is presented, leading to the neutral, carbonyl-derivatized products [{Si(SiMe3 )3 }3 Ge9 (CO)R'] (R'=Me, iPr, tBu, Ph, Bz, cyclopropylmethyl, phenethyl, 4-vinylphenyl). This reaction is applicable to a wide range of acyl chlorides and allows for diverse functionalization of Ge9 Zintl clusters. [{Si(SiMe3 )3 }3 Ge9 (CO)tBu] readily releases CO at ambient conditions under formation of [{Si(SiMe3 )3 }3 Ge9 tBu]. This temperature-dependent decarbonylation most likely proceeds via a radical Norrish-type I α-bond cleavage. Except for R'=tBu and Bz all obtained acyl-derivatized Ge9 cluster compounds do not release CO even at elevated temperatures. All compounds were characterized by NMR spectroscopy. [{Si(SiMe3 )3 }3 Ge9 (CO)R'] (R'=tBu, Ph, Me, iPr) as well as [{Si(SiMe3 )3 }3 Ge9 tBu] were further structurally characterized by single crystal X-ray diffraction.