Nature 325, 135 - 136 (08 January 1987); doi:10.1038/325135a0

A new clathrate hydrate structure

John A. Ripmeester^*, John S. Tse^*, Christopher I. Ratcliffe^* & Brian M. Powell^†

^*Division of Chemistry, National Research Council, Ottawa K1A OR6, Canada
^†Atomic Energy of Canada Limited, Chalk River Nuclear Laboratories, Chalk River, Ontario KOJ 1JO, Canada

Clathrate hydrates, ice-like host–guest systems containing guest molecules in cages of hydrogen-bonded water molecules exist in three well-characterized cubic forms, and a less well-characterized tetragonal form^1,2. On the basis of ²H and ^l29Xe NMR measurements and X-ray and neutron powder diffraction results, we now report a new hexagonal hydrate structure requiring both large and small guest molecules to stabilize the structure. This hydrate is expected to be isostructural with the hexagonal clathrasil dodecasil-lH (see ref. 14 for clathrasil nomenclature). As for the cubic clathrate hydrates, the new hydrate structure may occur naturally.

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