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Tetradihydrobenzoquinonate and Tetrachloranilate Zr(IV) Complexes: Single-Crystal-to-Single-Crystal Phase Transition and Open-Framework Behavior for K4Zr(DBQ)4
journal contribution
posted on 2013-10-07, 00:00 authored by Inhar Imaz, Georges Mouchaham, Nans Roques, Stéphane Brandès, Jean-Pascal SutterThe
molecular complexes K4[Zr(DBQ)4] and K4[Zr(CA)4], where DBQ2– and CA2– stand respectively for deprotonated dihydroxybenzoquinone and chloranilic
acid, are reported. The anionic metal complexes consist of Zr(IV)
surrounded by four O,O-chelating ligands. Besides the preparation
and crystal structures for the two complexes, we show that in the
solid state the DBQ complex forms a 3-D open framework (with 22% accessible
volume) that undergoes a crystal-to-crystal phase transition to a
compact structure upon guest molecule release. This process is reversible.
In the presence of H2O, CO2, and other small
molecules, the framework opens and accommodates guest molecules. CO2 adsorption isotherms show that the framework breathing occurs
only when a slight gas pressure is applied. Crystal structures for
both the hydrated and guest free phases of K4[Zr(DBQ)4] have been investigated.