Observations of tetrel bonding between sp-carbon and THF.

We report the direct observation of tetrel bonding interactions between sp-carbons of the supramolecular synthon 3,3-dimethyl-tetracyanocyclopropane () and tetrahydrofuran in the gas and crystalline phase. The intermolecular contact is established σ-holes and is driven mainly by electrostatic forces. The complex manifests distinct binding geometries when captured in the crystalline phase and in the gas phase. We elucidate these binding trends using complementary gas phase quantum chemical calculations and find a total binding energy of -11.2 kcal mol for the adduct. Our observations pave the way for novel strategies to engineer sp-C centred non-covalent bonding schemes for supramolecular chemistry.