Halogen Bonding between Thiocarbonyl Compounds and 1,2- and 1,4-Diiodotetrafluorobenzenes
Lauri Happonen, J. Mikko Rautiainen, Arto Valkonen
Abstract
The halogen bonding (XB) between 1,2-diiodotetrafluorobenzene (1,2-DITFB) or 1,4-diiodotetrafluorobenzene (1,4-DITFB) and the selection of different thiocarbonyl acceptors was studied by the single-crystal X-ray diffraction method. Diiodotetrafluorobenzenes (DITFBs) were found to form C-I···S halogen-bonded 1:1, 2:1, and 1:2 (donor/acceptor ratio) complexes with thiocarbonyls. Lengths of contacts were found to be clearly shorter than the sum of van der Waals radii of iodine and sulfur as well as the contact angles showed values close to linear, so the XB interactions could be verified. One sulfur atom showed the ability to accept one, two, or four XB interactions, and the acceptor angle can vary more than 35°. Solid-state packing of thiocarbonyl-XB complexes was found to be greatly affected by the size and type of the acceptor used. Halogen and hydrogen bonding cooperativity was found in some of the complexes if the used acceptor was suitable to form both bonds. Here, we present 19 new structures of these complexes, which can be rather easily prepared by mixing the components in the solutions and letting them crystallize in loosely sealed tubes. Computational analysis carried out for the XB complexes of N,N′-dimethylthiourea supported very closely the findings of the experimental study.