For the urea derivative DMI, a solution study 59 has revealed broad absorption maxima of the monohydrate in 1,2-dichloroethane (3431 cm -1 ) and CCl 4 (3460 cm -1 ) solution, downshifted by 162 and 155 cm -1 , respectively, from the monomer symmetric OH stretch of water in the same solution. We are not aware of structural data for the monohydrate in the gas phase, but there is evidence for involvement of the C=O group in the hydrogen bond and the DMI monomer has been characterised by rotational spectroscopy .