Unprecedented Size of the sigma-Holes on 1,3,5-Triiodo-2,4,6-trinitrobenzene Begets Unprecedented Intermolecular Interactions

作者：Goud N Rajesh; Bolton Onas; Burgess Emily C; Matzger Adam J^*

来源：Crystal Growth & Design, 2016, 16(3): 1765-1771.

DOI：10.1021/acs.cgd.6b00074

Halogen bonding is rapidly emerging as a reliable primary interaction at the disposal of the supramolecular chemist. With the sigma-hole of the halogen atom guiding the strength and directionality of these interactions, current research focuses on tuning the electrostatic potential of the sigma-hole via molecular design. We have designed and synthesized 1,3,5-triiodo-2,4,6-trinitrobenzene (TITNB), a compound which, to the best of our knowledge, exhibits the largest sigma-hole among organic halogenated compounds. The strength of halogen bonding through this enhancement of the sigma-hole is demonstrated here and probed through eight novel cocrystals containing TITNB. These cocrystals exhibit notably short halogen bonds. For instance, the I center dot center dot center dot S interaction in TITNB-thiourea and I center dot center dot O- contact in TITNB-4-picoline-N-oxide are the shortest known in their respective categories. Moreover, the primary interactions in all these cocrystals exhibit hierarchical pairing based on Lewis basicity of the donor, highlighting a predictable chemical recognition with potential for use in crystal engineering. Further, interaction energy calculations on TITNB and other triiodoarene derivatives computed using ammonia as halogen bond acceptor show that TITNB-NH3 exhibits the most stable interaction among halogen bond acceptors.

• 出版日期2016-3