Halogen Bond-Involving Supramolecular Assembly Utilizing Carbon as a Nucleophilic Partner of I⋅⋅⋅C Non-covalent...

Co-crystallization of 180°-orienting σ-hole-accepting tectons, namely, 1,4-diisocyanobenzene (1) and 1,4-diisocyanotetramethylbenzene (2), with such homoditopic halogen bond donors as 1,4-diiodotetrafluorobenzene (1,4-FIB) and 4,4'-diiodoperfluorobiphenyl (4,4'-FIBP) afforded co-crystals 1 ⋅ 1,4-FIB, 1 ⋅ 4,4'-FIBP, and 2 ⋅ 1,4-FIB. Their solid-state structures exhibit 1D-supramolecular arrangements, which are based on poorly explored I⋅⋅⋅C halogen bonding; this study is the first in which the supramolecular assembly utilizing halogen bonding with a terminal C atom was performed. The use of the potentially tetrafunctional σ-hole accepting tetraiodoethylene (TIE) leads to supramolecular architecture of a higher dimension, 3D-framework, observed in the structure of 1 ⋅ TIE. DFT calculations, used to characterize the halogen bonding situation, revealed that the I⋅⋅⋅C non-covalent interactions are moderately strong, ranging from -4.07 in 1 ⋅ TIE to -5.45 kcal/mol in 2 ⋅ 1,4-FIB. The NBO analysis disclosed that LP(C)→σ* charge transfer effects are relevant in all co-crystals.