Palladium complexes supramolecular

Kaneda et al. [33,34] have recently utilized acid-base interactions to non-covalently attach diphenylphosphine-4-benzoic acid palladium complexes to the exterior of poly(propyleneimine) dendrimers and to cavities within these dendrimers (Fig. 9) via the interaction of the benzoic acid with the carboxyl groups of amide moieties positioned within the dendrimer. Interestingly, the supramolecular dendritic catalyst gave rise to much more active catalysts for... 

FIGURE 24 Generation of supramolecular catalysts for allylic amination (89) (A) assembly of pseudoenantiomeric bisoxazoline derivatives. CAChe-minimized model of the palladium-containing supramolecular complex and (B) palladium-mediated enan-tioselective allylic amination. (See Color Insert in the back of this book.)... 

Kaseyama T, Takebayashi S, Wakabayashi R, Shinkai S, Kaneko K, Takeuchi M (2009) Supramolecular assemblies of polyamline through cooperative bundling by a palladium-complex-appended synthetic cross-Hnker. Chem Eur J 15 12627-12635. doi 10.1(X)2/ chem.200902305... 

Ebitani, K. and Kaneda, K. (2004) Supramolecular catalysts by encapsulating palladium complexes within dendrimers. Journal of the American Chemical Society, 126,1504. 

A non-covalently functionalized dendrimer was also applied in a continuous allylic amination reaction.[33] PPI dendrimers functionalized with urea adamantyl groups can act as host molecules for phosphorus ligands equipped with acetyl urea groups (Figure 4.18). The so formed supramolecular complex was reacted with a palladium precursor... 

A helical homobimetallic mercury(II) complex with a bridging bis(NHC) ligand serves as a starting point for a supramolecular assembly. Also tetrameric cyclic palladium(II) complexes have been obtained with bridging NHC-pyridine ligands. 

Scheme 15 Supramolecular interaction between perfluoro-tagged palladium phosphine complex 35 and polyglycerol perfluoroalkyl ester 34...

Metallomesogens have been shown to form helical supramolecular organisations in their mesophases [95]. Chiral oxazoline complexes with various metal ions and six alkyl chains did not show LC behaviour, but when mixed with trinitrofluorenone form achiral smectic A phases [96]. Furthermore, when a branch was included in the structure of the ligands (Fig. 12) the corresponding complexes with copper(II) and palladium(II) form columnar mesophases which have a helical organisation [97]. The presence of the stereogenic centre near the central metal ion in these complexes (Fig. 12) is enough to cause the parallel molecules to stack in a tilted manner with... 

The supramolecular binding motifs described here were also used to attach catalysts to solid (silica) supports (128). The active metal complex could be switched from palladium to rhodium by using a polar solvent that breaks up the binding of the supramolecular motif. Allylic alkylation and hydroformylation catalysis could be carried out by using the same support "receptor" material and different "guest" ligands for the two metals a... 

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