Xantphos-based diphosphine ligands

Figure 8.7 Encapsulation of palladium in a heterocapsule formed by ionic interactions between a concave Xantphos-based diphosphine ligand and a tetraanionic calix[4]arene.

A family of wide bite angle diphosphine ligands based upon xantphos (8) has been developed and tested in rhodium catalysed hydroformylation. van Leeuwen and co-workers conducted HP IR measurements on a range of Rh/thixantphos... 

Both diphosphite and diphosphine based catalysts have been reported that will even hydroformylate internal aUcenes to mainly linear products [26,27]. The ligands are based on bisphenol and Xantphos backbones shown in Fig. 6.3. 

Haynes and associates carried out a mechanism study for Rh/Xantphos-cata-lyzed methanol carbonylation based on the combination of structural, spectroscopic, kinetic, and theoretical methods. The Rh(III) acetyl complex [Rh(Xantphos)-(COMe)l2], as the catalyst resting state, was isolated and shown to adopt a nearly octahedral geometry with the Xantphos ligand coordinated in a pincer k -P,0,P fashion, which differs from related acetyl complexes with cis-chelating diphosphines that adopt square-pyramidal structures. 

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