Persistent Digermenes with Acyl and α‐Chlorosilyl Functionalities

Abstract

We report the preparation of α‐chlorosilyl‐ and acyl‐substituted digermenes. Unlike the corresponding transient disilenes, these species with a Ge=Ge double bond show an unexpectedly low tendency for cyclization, but in turn are prone to thermal Ge=Ge bond cleavage. Triphenylsilyldigermene has been isolated as a crystalline model compound, and is the first fully characterized example of a neutral digermene with an A2GeGeAB substitution pattern. Spectroscopic and computational evidence prove the constitution of 1‐adamantoyldigermene as a first persistent species with a heavy double bond conjugated with a carbonyl moiety.

A Mixed Heavier Si=Ge Analogue of a Vinyl Anion

“…The longest wavelength UV/Vis absorption is located at λ max =436 nm ( ϵ =10 570 L mol −1 cm −1 ). The blue‐shift in 4 a compared to 3 ⋅K(THF) ( λ max =490 nm, for comparison to TD‐DFT results see Supporting Info) is reminiscent of similar observations for the reaction of Tip 2 Ge=Ge(Tip)Li with the same Ph 3 SiCl substrate [24] . Single‐crystal X‐ray diffraction analysis confirmed the constitution of 4 a as silyl‐substituted silagermene (Figure 3 a).…”

“…The blue-shift in 4 a compared to 3•K(THF) (l max = 490 nm, for comparison to TD-DFT results see Supporting Info) is reminiscent of similar observations for the reaction of Tip 2 Ge=Ge(Tip)Li with the same Ph 3 SiCl substrate. [24] Single-crystal X-ray diffraction analysis confirmed the constitution of 4 a as silyl-substituted silagermene (Figure 3 a). The Ge1 À Si1 bond of 2.2020(2) is slightly shorter than in 3•K (18-c-6).…”

“…The 29 Si NMR resonance of 4 a at δ =136.6, −1.6 and −7.6 is upfield shifted compared to 3 ⋅K(THF). The signal at δ =−1.6 assigned to the Ph 3 Si unit is slightly upfield shifted compared to triphenylsilyl substituted digermene (Tip 2 Ge=GeTip(SiPh 3 ); δ 29 Si=1.9) [24] …”

“…The signal at d = À1.6 assigned to the Ph 3 Si unit is slightly upfield shifted compared to triphenylsilyl substituted digermene (Tip 2 Ge = GeTip-(SiPh 3 ); d 29 Si = 1.9). [24] The longest wavelength UV/Vis absorption is located at l max = 436 nm (e = 10 570 L mol À1 cm À1 ). The blue-shift in 4 a compared to 3•K(THF) (l max = 490 nm, for comparison to TD-DFT results see Supporting Info) is reminiscent of similar observations for the reaction of Tip 2 Ge=Ge(Tip)Li with the same Ph 3 SiCl substrate.…”

Ein gemischtes, schwereres Si=Ge Analogon eines Vinylanions

“…Die UV/Vis Absorption mit der längsten Wellenlänge liegt bei λ max =436 nm ( ϵ =10 570 L mol −1 cm −1 ). Die Blauverschiebung in 4 a im Vergleich zu 3 ⋅K(THF) ( λ max =490 nm, zum Vergleich mit TD‐DFT Ergebnissen siehe Hintergrundinformationen) erinnert an ähnliche Beobachtungen für die Reaktion von Tip 2 Ge=Ge(Tip)Li mit dem gleichen Ph 3 SiCl Substrat [24] . Durch Röntgenbeugung an Einkristallen wurde die Konstitution von 4 a als silylsubstituiertes Silagermen (Abbildung 3 a) bestätigt.…”