The structure of the ionic clathrate hydrate of tetrabutylammonium valerate (C4H9)4NC4H9CO2·39.8H2O

Abstract

For the first time the detailed crystal structure of the ionic clathrate hydrate of tetrabutylammonium valerate (C₄H₉)₄NC₄H₉CO₂·39.8H₂O 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·P and small D cavities. Butyl chains of the cation and the anion of (C₄H₉)₄NC₄H₉CO₂ 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.