Engineering Crystals Using sp³‐C Centred Tetrel Bonding Interactions

1,1,2,2‐Tetracyanocyclopropane derivatives 1 and 2 were designed and synthesized to probe the utility of sp³‐C centred tetrel bonding interactions in crystal engineering. The crystal packing of 1 and 2 and their 1,4‐dioxane cocrystals is dominated by sp³‐C(CN)₂⋅⋅⋅O interactions, has significant C⋅⋅⋅O van der Waals overlap (≤0.266 Å) and DFT calculations indicate interaction energies of up to −11.0 kcal mol⁻¹. A cocrystal of 2 with 1,4‐thioxane reveals that the cyclopropane synthon prefers interacting with O over S. Computational analyses revealed that the electropositive C₂(CN)₄ pocket in 1 and 2 can be seen as a strongly directional ‘tetrel‐bond donor’, similar to halogen bond or hydrogen bond donors. This disclosure is expected to have implications for the utility of such ‘tetrel bond donors’ in molecular disciplines such as crystal engineering, supramolecular chemistry, molecular recognition and medicinal chemistry.