Geminal Charge-Assisted Tetrel Bonds in Bis-Pyridinium Methylene Salts.

C(sp 3 ) atoms are known to act as electrophilic sites in self-assembly processes, and in all cases reported till now, they form only one interaction with nucleophiles; that is, they function as monodentate tetrel bond donors. This manuscript reports experimental (X-ray structural analysis) and theoretical evidence (DFT calculations), proving that the methylene carbon in bis-pyridinium methylene salts establishes two short and directional C(sp 3 )···anion interactions; that is, they function as bidentate tetrel bond donors.