C(sp3) 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(sp3)···anion
interactions; that is, they function as bidentate tetrel bond donors.