A co-crystal between benzene and ethane, an evaporite material for Saturn's moon Titan

Abstract

Using synchrotron powder diffraction the structure of a co-crystal between benzene and ethane has been determined. The structure is remarkable, a lattice of benzene molecules playing host to ethane molecules. This is demonstrated by the similarity between the interactions found in the co-crystal structure and those in the pure structure, showing that the C-H...{\pi} network of benzene is maintained as a 'host' but expands to allow the ethane 'guest' to situate within the channels that result from this network. The co-crystal is determined to be a 3:1 benzene:ethane co-crystal and its structure is described by the trigonal space group $R\bar{3}$ with a = 15.977(1) {\AA} and c = 5.581(1) {\AA} at 90 K, resulting in a density of 1.067 g$\cdot$cm$^{-3}$. Conditions under which this co-crystal forms indicate that it could readily be present on the surface of Saturn's moon Titan as an evaporite deposit following the evaporation of hydrocarbon fluids.