Closely following the procedure for the preparation of the base-stabilized dichlorosilylene complex NHC ⋅SiCl reported by Roesky, Stalke, and co-workers (Angew. Chem. Int. Ed. 2009, 48, 5683-5686), a few crystals of the salt [NHC -H⋅⋅⋅Cl⋅⋅⋅H-NHC ]Si(SiCl ) were isolated, aside from the reported byproduct [NHC -H ⋅⋅⋅Cl ], and characterized by X-ray crystallography (NHC =N,N-di(2,6-diisopropylphenyl)imidazo-2-ylidene). They contain the weakly coordinating anion Si(SiCl ) , which was also obtained in high yields upon deprotonation of the conjugate Brønsted acid HSi(SiCl ) with NHC or PMP (PMP=1,2,2,6,6-pentamethylpiperidine). The acidity of HSi(SiCl ) was estimated by DFT calculations to be substantially higher than those of other H-silanes. Further DFT studies on the electronic structure of Si(SiCl ) , including the electrostatic potential and the electron localizability, confirmed its low basicity and nucleophilicity compared with other silyl anions.