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Towards Clathrates: Frozen States of Hydration of tert-Butylamine†

 Dr. Łukasz Dobrzycki1,*, Paulina Taraszewska1, Prof. Dr. Roland Boese1,2,*, Prof. Dr. Michał K. Cyrański1 and Dr. Sebastian A. Cirkel3


Author Information

1. Faculty of Chemistry, University of Warsaw, Pasteura 1 str., 02093 Warsaw (Poland)

2. Cluster of Excellence RESOLV, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum (Germany)

3. Faculty of Chemistry, University Duisburg-Essen, Universitätsstrasse 7, 45117 Essen (Germany)

 

 

Angew. Chem. Int. Ed. 2015,54,10138-10144

[DOI: 10.1002/ange.201412331]

 

Abstract

The dilution of tert-butylamine (tBA) with water and subsequent cooling leads to a large series of different crystalline hydrates by an in situ IR laser melting-zone procedure. The crystal structures were determined for tBA⋅n H2O, with n=0.25, 1, 7.25 , 7.75, 9.75 , 11, and 17. For the two lower hydrates (n=0.25, 1), one- and two-dimensional hydrogen-bonded networks are formed, respectively. The higher hydrates (n>1) exhibit a clathrate-like three-dimensional water framework with the tBA molecules as part of, or sitting inside, the cages. In all cases, tBA is hydrogen-bonded to the H2O framework. In the intermediate range (1<n<7 .25), crystallization is hindered, and no crystalline phases could be observed. The crystal structures that are achieved from the dilution of tBA with water are considered to be frozen stages of hydration, describing the genesis of such clathrate-like structures, finally ending at ice as an example of an infinitely diluted hydrate.

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