Isolable T-Shaped Planar Silyl Anion.

Silyl anions have garnered significant attention due to their synthetic abilities. However, previously reported silyl anions have been limited to either trigonal-pyramidal or trigonal-planar geometries, which confine them primarily as nucleophiles in substitution reactions. Herein, we report the isolation of the unprecedented T-shaped planar silyl anion salt 2 by employment of a geometrically constrained triamido pincer ligand. Theoretical calculations disclosed that the silicon centre in 2 possesses both a lone pair of electrons and an empty 3p z orbital. In addition to nucleophilic substitution reactions with Ph 3 PAuCl and W(CO) 6 , 2 readily undergoes oxidative additions with CO 2 and 2,6-dimethylphenylisonitrile at room temperature. Furthermore, under mild conditions, compound 2 cleaves C sp2 -H, C sp2 -H, and H-H bonds in 1,2,4,5-tetrafluorobenzene, an intramolecular i Pr group, and dihydrogen, representing the first examples of C-H and H-H activations mediated by a silyl anion, respectively. This work unveils new reactivity of silyl anions owing to the non-classical geometry and electronic structure.