Syntheses and ¹H NMR spectra of substituted zintl ions [Ge ₉R_n]^(4-n)-: Crystal structures of [Ge ₉R]^3- (R = 2,4,6-Me₃C₆H₂, CHCH₂) and indication of tris-vinylated clusters

The introduction of a mesityl (Mes; 2,4,6-Me₃C₆H ₂) ligand to a Ge₉ polyanion is accomplished by the reaction of [Ge₉]^4- solutions with Ag₄Mes ₄. The crystal structure investigation of its [K([2.2.2]crypt)] salt ([2.2.2]crypt: 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) shows that [Ge₉Mes]^3- comprises one exo-bonded aryl ligand in accordance with the ¹H NMR spectroscopic data. The formation of mono-, bis-, and tris-substituted Zintl Ions [Ge₉R_n] ^(4-n)- (n = 1, 2, and 3; R = CHCH₂) is investigated by ¹H NMR spectroscopy. The mono- and bis-vinylated Ge₉ clusters, [Ge₉(CHCH₂)]^3- and [Ge ₉(CHCH₂)₂]^2-, were obtained by the reaction of K₄Ge₉ with Me₃SiC≡CSiMe ₃ in ethylenediamine. In the presence of [18]crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) and K(C₅H₅) crystals containing both cluster species were isolated and structurally characterized as[K([18]crown-6)]₂{(η⁵-C ₅H₅)[K([18]crown-6)]₂}[Ge₉(CHCH ₂)]and [K([18]crown-6)]{(η⁵-C ₅H₅)[K([18]crown-6)]₂}[Ge₉(CHCH ₂)₂], respectively. ¹H NMR experiments hint for the tris-vinylated cluster [Ge₉(CHCH₂)₃] ^-.