Simple design for metal-based halogen-bonded cocrystals utilizing the M-Cl center dot center dot center dot I motif

摘要

We demonstrate a strategy for synthesizing halogen-bonded metal-organic cocrystals by utilizing metal complexes whose pendant chloride group enables halogen bonding. A series of 12 cocrystals involving octahedral CoCl2L2 complexes (L = 2,2'-bipyridine or 1,10 phenantroline) as halogen bond acceptors were prepared by both liquid-assisted grinding and conventional solution-based methods. The efficacy of this strategy is evident by the assembly of a large family of cocrystals involving six perfluorinated halogen bond donors: 1,4-diiodotetrafluorobenzene, 1,3-diiodotetrafluorobenzene, 1,2-diiodotetrafluorobenzene, 1,3,5triiodotrifluorobenzene, iodopentafluorobenzene and octafluoro-1,4-diiodobutane. Single crystal X-ray diffraction experiments have shown that cocrystals display different crystal packing governed by CI center dot center dot center dot I halogen bonds between halogen bond donor iodine atoms and metal complex chlorine atoms (varying from 3.061 to 3.471 angstrom) based on zero-, one-, two- and three- dimensional halogen-bonded architectures.