Supramolecular bidentate ligands

Supramolecular chemistry also provides new tools for catalyst anchoring. We have shown that catalysts can be noncovalently attached to various soluble and insoluble supports, affording recyclable catalysts. Interestingly, the reversible nature of the noncovalent bond gives rise to new opportunities. In the first instance, we foresee an important role for supramolecular bidentate ligands in combinatorial catalysis - but as a consequence of the entirely new properties many new applications are envisioned. We look forward to new developments and results in this exciting emerging area of supramolecular catalysis. 

Sandee, A.J., v.d. Burg, Lidy, and Reek. J.N.H. (2007) UREAphos supramolecular bidentate ligands for asymmetric hydrogenation. Chem. Commun., 864-866. 

The simplest supramolecular bidentate ligand derives from secondary phosphine oxides (SPO). Complexes of transition metals with SPOs have been known for 45 years, and they were introduced as catalysts by van Leeuwen and Roobeek in the early 1980s (66). The complex used first was a platinum hydride containing two SPOs, cormected to one another by a strong hydrogen bond, and a triphenylphosphine to complete the coordination sphere. SPOs have a very strong tendency to occur in pairs connected by hydrogen bonds in many metal complexes they act as bidentate monoanions. 

The use of other potential bidentate ligands also permits the synthesis of cyclic trinuclear gold complexes that form, by stacking, supramolecular assemblies. This is the case for the trinuclear complex [Au3(NC5H4)3] [47] that crystallizes in two... 

Breit, B. (2005) Supramolecular approaches to generate libraries of chelating bidentate ligands for homogeneous catalysis. Angeiv. Chem., Int. Ed.. 44, 6816-6825. 

Supramolecular Construction of Chelating Bidentate Ligand Libraries through Hydrogen Bonding Concept and Applications in Homogeneous Metal Complex Catalysis... 

I 2 Supramolecular Construction of Chelating Bidentate Ligand Libraries... 

FigureS.I Useoffunctional groups to form encapsulated catalysts by assembly (A), to form bidentate ligands by assembly (B), and to support the catalyst by supramolecular interactions (C).

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