Rhodium complexes with BINAPHOS and related ligands

2 Rhodium complexes with BINAPHOS and related ligands. 

The first R/S indicator refers to the binaphthyl (biphenyl) bridge and the second to the bisnaphthol (bisphenol) moiety. Thus for 26, which lacks the bisphenol chirality, we write in the table (R,-), and for 28, which contains a non-chiral biphenyl bridge, we write (-,R). 

The [Rh(acac)(phosphine-phosphite] complexes were used as precursors for the asymmetric hydroformylation of styrene after adding 3 equivalents of free ligand. The results are shown in Table 3. The ee of the product decreases with increasing temperature. The ratio of CO to H2 does not affect the regio- and enantioselectivity. 

Slyrene 20 mmols in benzene. pUi] = O.OlOmmol. L = 0.040 mmoL The ee s were determined by GLC analysis of the corresponding 2-arylpropionic acids derived by Jones oxidation of the products 

The spectroscopic data of phosphine-phosphite complexes show slight differences between the (R,S) and (S,R) complexes on the one hand and the (R,R) and (S,S) complexes on the other. In the latter compounds the data are less clear-cut, which could be due to stmctural deviations of the monohydride complexes from an ideal trigonal bipyramid or to equilibria between isomers. The two ea isomers cannot be distinguished by IR spectroscopy as their absorptions tend to coincide [49], 

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