Calix[4]arene‐Phosphine Dimers: Precursors of Flexible Metallo‐Capsules and Self‐Compacting Molecules |
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Authors: | Soheila Sameni Catherine Jeunesse Dr Dominique Matt Dr Loïc Toupet Dr |
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Institution: | 1. Laboratoire de Chimie Inorganique Moléculaire et Catalyse, Institut de Chimie UMR 7177 CNRS, Université de Strasbourg, 1 rue Blaise Pascal, 67008 Strasbourg Cedex (France);2. Groupe Matière Condensée et Matériaux, UMR 6626 CNRS, Université de Rennes 1, 35042 Rennes Cedex (France) |
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Abstract: | The first diphosphines based on a double calixarene, namely 1,4 (or 1,3)‐bis‐(5‐diphenylphosphino‐25,26,27,28‐tetrapropoxycalix4]aren‐17‐yl)benzene ( L2 , L3 ) were each prepared in four steps starting from 5,17‐dibromo‐25,26,27,28‐tetrapropoxycalix4]arene. Upon reaction of L2 with Au(tht)(thf)]BF4, (tht=C4H8S) a rigid metallo‐capsule was quantitatively formed, which adopts an oblique form owing to the distinct nature of the spacers linking the two calixarene half‐spheres. In the solid state, the 1,4‐substituted phenylene linker is turned towards the gold ion, suggesting the existence of weak bonding interactions between two aromatic CH protons of this ring and the metal centre (Au???H=2.67 Å). In contrast to this gold complex, the related silver complex shows dynamic behaviour in solution, the exchange between two enantiomeric oblique forms being facilitated by the greater stereochemical flexibility of AgI vs. AuI. A heteronuclear 109Ag{1H} HMQC experiment established strong correlations between the CH protons of the phenylene linker and the 109Ag ion. Dynamic behaviour similar to that observed for the silver complex was further observed in trans‐PtCl2? L2 ], a chelate complex that could be obtained quantitatively from L2 and PtCl2(PhCN)2]. The intended formation of a chelate complex leading to a capsule with an endo‐oriented metal centre was achieved by reacting L3 with Pd(allyl)(thf)2]BF4. The complex thus formed constitutes the first organometallic transition metal complex embedded in a cavity with large portals. Binding of RuCl2(p‐cymene)] to L2 and L3 resulted in self‐compacting bimetallic complexes in which each calixarene basket entraps a Ru(p‐cymene) unit, thereby forming molecules occupying a minimal volume. |
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Keywords: | calixarenes chelates metallocapsules phosphines self‐compacting molecules supramolecular chemistry |
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