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Calix[4]arene‐Phosphine Dimers: Precursors of Flexible Metallo‐Capsules and Self‐Compacting Molecules
Author(s) -
Sameni Soheila,
Jeunesse Catherine,
Matt Dominique,
Toupet Loïc
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200901629
Subject(s) - chemistry , calixarene , phosphine , phenylene , crystallography , metal , molecule , heteronuclear molecule , linker , chelation , ring (chemistry) , stereochemistry , polymer chemistry , medicinal chemistry , nuclear magnetic resonance spectroscopy , inorganic chemistry , organic chemistry , catalysis , computer science , operating system , polymer
The first diphosphines based on a double calixarene, namely 1,4 (or 1,3)‐bis‐(5‐diphenylphosphino‐25,26,27,28‐tetrapropoxycalix[4]aren‐17‐yl)benzene ( L 2 , L 3 ) were each prepared in four steps starting from 5,17‐dibromo‐25,26,27,28‐tetrapropoxycalix[4]arene. Upon reaction of L 2 with [Au(tht)(thf)]BF 4 , (tht=C 4 H 8 S) 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 Ag I vs. Au I . A heteronuclear 109 Ag{ 1 H} HMQC experiment established strong correlations between the CH protons of the phenylene linker and the 109 Ag ion. Dynamic behaviour similar to that observed for the silver complex was further observed in trans ‐[PtCl 2 ⋅ L 2 ], a chelate complex that could be obtained quantitatively from L 2 and [PtCl 2 (PhCN) 2 ]. The intended formation of a chelate complex leading to a capsule with an endo ‐oriented metal centre was achieved by reacting L 3 with [Pd(allyl)(thf) 2 ]BF 4 . The complex thus formed constitutes the first organometallic transition metal complex embedded in a cavity with large portals. Binding of [RuCl 2 ( p ‐cymene)] to L 2 and L 3 resulted in self‐compacting bimetallic complexes in which each calixarene basket entraps a Ru( p ‐cymene) unit, thereby forming molecules occupying a minimal volume.