Cleavage of the Ge-Ge Bond in Bis(germylene) LGe-GeL with Diverse Small Molecules

In view of the promising potential of tetrylenes, the reactivity of bis(germylene) compound LGe-GeL (1) (L = PhC(NtBu)₂) toward various small molecules was comprehensively investigated. Reactions of bis(germylene) with unsaturated bonds rationally resulted in the cleavage of the Ge-Ge bond, and the insertion of isocyanate into the Ge-Ge bond was determined. However, when reacting with isothiocyanate, an unprecedented cleavage of the C═S bond led to the formation of a heavier ester analogue of germanium concomitant with isonitrile. Therefore, we further investigated the reactions of 1 with chalcogen substances (S₈ and Se) that afforded the heavier anhydride analogues, which could also be obtained by treating the heavier ester analogue with elemental sulfur. Furthermore, the insertion of carbon disulfide into the Ge-Ge bond was explored, indicating an intramolecular zwitterionic character. Notably, the reaction of 1 with methyl 2-butynoate represents the first example of alkyne activation by this type of bis(germylene) system. All compounds were fully characterized by nuclear magnetic resonance spectroscopy and structurally well-defined. The reactivity potential of 1 and the related reaction mechanisms were theoretically studied in detail.