Water soluble organometallic chemistry has received significant interest in the last few years, particularly inthe area of biphasic catalysis. The most widely studied water soluble transition metal complexes are those with sulfonated phosphines, eg (m-sulfonatophenyl) diphenyl phosphine (TPPMS) and tris (zn-sulfonatophenyl) phosphine (TPPTS). 2*" 0 Sulfonated tertiary phosphines are employed, for example, in a low temperature and pressure industrial hydroformylation process26" 1 and in laboratory scale asymmetric hydrogenations. 3 These complexes display spectroscopic properties similar to their water-insoluble ana-logues. 4 Consequently, they are often assumed to have the same catalytic propertiesand utilize a similar mechanism. However, water often plays an intimate role in aqueous catalysisin unanticipated ways, and many factors need to be taken into account that are irrelevant in organic solvents. 5