Diphenylphosphinate complexes

The previous extension of solvent mixtures involved solvent interfaces. This organic-water interfacial technique has been successfully extended to the synthesis of phenylacetic and phenylenediacetic acids based on the use of surface-active palla-dium-(4-dimethylaminophenyl)diphenylphosphine complex in conjunction with dode-cyl sodium sulfate to effect the carbonylation of benzyl chloride and dichloro-p-xylene in a toluene-aqueous sodium hydroxide mixture. The product yields at 60°C and 1 atm are essentially quantitative based on the substrate conversions, although carbon monoxide also undergoes a slow hydrolysis reaction along with the carbonylation reactions. The side reaction produces formic acid and is catalyzed by aqueous base but not by palladium. The phosphine ligand is stable to the carbonylation reactions and the palladium can be recovered quantitatively as a compact emulsion between the organic and aqueous phases after the reaction, but the catalytic activity of the recovered palladium is about a third of its initial activity due to product inhibition (Zhong et al., 1996). 

Rhenium tricarbonyl complexes containing substituted cyclopentadi-enyl and bis diphenylphosphine ligands also were investigated as anticancer agents. The antiproliferative effects on breast cancer of complex A shown in Fig. 23 were examined relative to the known active metabolite, 4-hydroxy tamoxifen, and found to have a similar effect [107]. The cytotoxicity of five rhenium tricarbonyl bis-diphenylphosphine complexes B shown in Fig. 23 was examined for 18 different human cancer cell lines. The tests showed that all the complexes were active against specific tumor cell lines, especially a line of breast and uterine cancer [108]. 

Diphosphines are of considerable interest as ligands because of their excellent donor chelating properties with transition-metal ions, and are used to stabilize unusual oxidation states. Complexes formed with ethylenebis(dimethylphosphine) have increased electron density at the metal atom and are particularly reactive compared with the analogous ethylenebis(diphenylphosphine) complexes.1... 

Benyei, A. Stafford, J.N.W. Katho, A. Darensbourg, D.J. Joo, F. (1993) The effect of phosphonium salt formation on the kinetics of homogeneous hydrogenations in water utilizing a rhodium mera-sulfonatophenyl-diphenylphosphine complex, J. Mol Catal, M, 157-63. 

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