The structure of the ionic clathrate hydrate of tetrabutylammonium valerate (C4H9)(4)NC4H9CO2 center dot 39.8H(2)O

For the. first time the detailed crystal structure of the ionic clathrate hydrate of tetrabutylammonium valerate (C4H9)(4)NC4H9CO2 center dot 39.8H(2)O has been determined by single crystal X-ray analysis at 150 K. The idealized water-anion host framework consists of five-compartment polyhedral cavities 4T center dot P and small D cavities. Butyl chains of the cation and the anion of (C4H9)(4)NC4H9CO2 are included in the five-compartment cavities with displacement of two inner'' host water molecules. The inclusion of the guest entities leads to the distortion of D-cavities which are partially. filled by additional guest'' water molecules. The other D-cages are empty. The structure exhibits significant disordering. The adequate model of disordering and inclusion mode of the guest moieties have been obtained. Special features of the crystal structures of ionic clathrate hydrates of tetraalkylammonium carboxylates are discussed.