Perfluorocarbon-Hydrocarbon Discrete Intermolecular Aggregates: an Exceptionally Short N···I Contact
Supramol. Chem. 2002, 14, 47
F. Fontana, A. Forni, P. Metrangolo, W. Panzeri, T. Pilati, G. Resnati
Crystal packing viewed down the <i>b</i> axis of the halogen-bonded trimers formed by <i>N,N,N-tetramethylethylene-diamine and 1-iodoperfluoroheptane. Colours are as follows: black, carbon and hydrogen; blue, nitrogen; red, iodine; green, fluorine. Dotted lines represent weak H···F hydrogen bonds. Dashed lines represent N···I halogen bonds.'>
Crystal packing viewed down the b axis of the halogen-bonded trimers formed by N,N,N',N'-tetramethylethylene-diamine and 1-iodoperfluoroheptane. Colours are as follows: black, carbon and hydrogen; blue, nitrogen; red, iodine; green, fluorine. Dotted lines represent weak H···F hydrogen bonds. Dashed lines represent N···I halogen bonds.
ABSTRACT
1-Iodoperfluoroheptane and tetramethylethylenediamine (TMEDA) form a 2:1 ratio stable aggregate. A similar behaviour is shown by several other 1-iodoperfluoroalkanes and arenes. These aggregates have been characterised in solution by 1H / 19F-NMR spectroscopy and in the solid state through IR and single crystal X-ray diffraction. The determined structure of the cocrystal between TMEDA and 1-iodoperfluoroheptane shows the second shortest N···I interaction found in the crystallographic literature [2.762(3) Å] and the interdigitation of perfluorocarbon and hydrocarbon modules due to co-operative -C-H···F-C- interactions. Calculations with the aim to quantify the strength of these latter interactions have been also performed.