Werner clathrate formation with polyaromatic hydrocarbons: comparison of different crystallisation methods

Abstract

The single crystal structures of the Werner host, bis-isothiocyanato tetrakis-vinylpyridine nickel(II), H, with seven polyaromatic hydrocarbons (PAHs), indene (IND), naphthalene (NAP), azulene (AZU), fluorene (FLU), anthracene (ANT), phenanthrene (PHE) and pyrene (PYR) have been elucidated. The isomorphous and isostructural behaviours of these structures were scrutinised. The inclusion compounds can be formed using a variety of crystallisation methods such as solution crystallisation, grinding, slurrying and co-melting. Grinding allowed determination of rate constants of formation for the host with NAP at room temperature and with AZU at 35 °C. The kinetics of thermal decomposition of the inclusion compounds using non-isothermal methods permitted the establishment of the activation energies of the decomposition reactions with NAP and IND. Product formation in an ambient water slurry was successful with guests NAP and AZU showing low solubility at room temperature; for PHE, PYR and FLU this occurred only after longer stirring at a higher temperature (50 °C) at which the guests had low levels of solubility and for ANT no successful slurrying results were reached.