Trimethylphosphine. reaction with rhodium

Tetrakis(trimethylphosphine)rhodium(I) chloride loses two trimethylphosphine ligands when allowed to react with PPh3 at elevated temperatures (equation 52). The ionic compound also undergoes a more complex reaction with benzene and sodium. In this a trimethylphosphine ligand is converted to a PMe2Ph ligand (equation 53).186 The geometry adopted by both these complexes... 

The addition of trimethylphosphine to these rhodium/zeolite catalysts destroyed all catalytic activity because the phosphine was small enough to fit into the zeolite cavity and could deactivate all of the rhodium in the catalyst. The bulky tributylphosphine, however, could not enter the cavity and, thereby, only blocked the external rhodium from further reaction. This specific blocking enhanced the selectivity in the hydrogenation of a mixture of cyclopentene and 4-methylcyclohexene over a Rh/ZSM-11 catalyst. After treatment of the catalyst with tributylphosphine to block the external catalytically active sites, only the... 

The aldol reactions of rhodium enolates have limited synthetic utility when employed stoichiometri-cally. 0-Bound rhodium enolates of ketones, e.g. (36), have been prepared in high yield by reaction of preformed potassium enolates with carbonyldi(trimethylphosphine)ihodium(I) chloride or fluoride. However, the basic nature of these particular enolates restricts their aldol reactions to nonenolizable aldehydes. 

Scheme 7.2 Reactions of the surface 7t-allyl rhodium siloxide complex with trimethylphosphine.

For this complex, molecular chemistry does not adequately model the surface reactivity and the latter is strongly influenced by the presence of surface hydroxyl groups [22]. The organometallic fragments immobilized on silica have been reacted with trimethylphosphine to afford different silica-supported phosphine complexes of rhodium. The course of the reaction depends strongly on the hydroxyl content of the silica surface [23] (Scheme 7.2). 

In contrast, reaction of a THF solution containing a mixture of the rhodium isomers 79b and 80b with trimethylphosphine in the dark consumes only the 1,2,3,6-q isomer 80b to give the new PMe3 adduct 83 (169). The... 

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