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 3pz orbital. In addition to nucleophilic substitution reactions with Ph3PAuCl and W(CO)6, 2 readily undergoes oxidative additions with CO2 and 2,6‐dimethylphenylisonitrile at room temperature. Furthermore, under mild conditions, compound 2 cleaves Csp2−H, Csp2−H, and H−H bonds in 1,2,4,5‐tetrafluorobenzene, an intramolecular iPr 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. This work presents the isolation of an unprecedented T‐shaped planar silyl anion salt. The non‐classical geometry enables this silyl anion to feature a silicon‐centred HOMO, LUMO and a small HOMO–LUMO energy gap. It not only exhibits nucleophilic behaviour but also undergoes oxidative additions to CO2 and arylisonitrile. Notably, it represents the first example of silyl anions capable of cleaving C−H and H−H bonds under mild conditions.