Phosphorus···Iodine Halogen Bonding in Cocrystals of Bis(diphenylphosphino)ethane (dppe) and p-Diiodotetrafluorobenzene (p-F4DIB)

Adam M. Siegfried
Hadi D. Arman, Clemson University
Khadijatul Kobra, Clemson University
Kunhuan Liu
Andrew J. Peloquin, Clemson University
Colin McMillen, Clemson University
Timothy Hanks, Furman University
Bill Pennington, Clemson University


Three new cocrystals of bis(diphenylphosphino)ethane (dppe) and p-diiodotetrafluorobenzene (p-F4DIB) were studied using single-crystal X-ray crystallography. Two polymorphs containing a 1:1 dppe:p-F4DIB ratio were obtained, each displaying strong P···I halogen bonding along steplike chains. Additionally, a cocrystal with a 1:3 dppe:p-F4DIB ratio was studied. This cocrystal displays a similar main steplike chain to the 1:1 cocrystals, with pendant p-F4DIB molecules along the chain. In all three of the cocrystals, face-to-face and face-to-edge interactions involving both the phenyl rings and the perfluorobenzene rings contribute to the packing of the halogen bonded chains. Computational studies, including Hirshfeld surface analysis and ab initio calculations, were conducted to further elucidate the varying factors contributing to the packing of the cocrystals and the resulting structural stability.