General characteristics of aqueous organometallic catalysis

In the simplest form of aqueous organometallic catalysis (AOC) the reaction takes place in a homogeneous aqueous solution. This requires all 

Deterioration of catalysts is an everyday experience from working with highly water-sensitive compounds in insufficiently dried solvents, but in the reactions within aqueous organometallic catalysis water is either innocuous (this is the case with [RhCl(PPh3)3]) or may even be advantageous, taking an active part in the formation of catalytically active species. 

It is often useful to keep some of the reactants or the products in separate phases (principle of chemical protection by phase separation [53]). For instance, when the reaction is inhibited by its own substrate having the latter in an other phase than the one in which the catalyst is dissolved helps to eliminate long induction periods or complete stop of the reaction. An example is the biphasic hydrogenation of aldehydes with the water-soluble 

Elschenbroich, A. Salzer, Organometallics. A Concise Introduction, VCH, Weinheim, 1989, p. 234 

Bjerrum, J. C. Chang, Proc. XIII. Int. Conf. Coord. Chem. (Cracow-Zakopane, Poland, 1970) p. 229 

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