ABSTRACT
The previously unknown dianionic species 3a,b with exocyclic structures were synthesized by the reaction of the corresponding cyclic acylgermanes with 2.1 equivalence of KOtBu. The structural properties of the resulting products were analyzed by a combination of nuclear magnetic resonance and ultraviolet–visible absorption spectroscopy, single X-ray crystallography, and density functional theory quantum chemical calculations, and it has been found that 2a–c and 3b,c are best described by the keto-form (resonance structure I) in solution as well as in the solid state. The reactivity of 2a–c and 3b,c toward a variety of selected electrophiles was also examined.