Ditertiary phosphine oxides

Tertiary phosphine oxides are obtained from phosphinic chlorides and Grignard reagents,397 and ditertiary phosphine oxides similarly from di-Grignard reagents.398... 

Figure 6 Oxidative addition and metathetical reactions of complexes containing ditertiary phosphines...

The other hydrogen halides add oxidatively to rhodium(I) complexes of ditertiary phosphines or arsines giving rise to numerous monohydrido complexes, whose physical properties are also listed in Table 79. However, it is possible to prepare certain monohydrido complexes from rhodium(III) halides. One interesting reaction, carried out under an atmosphere of CO, gives rise to dicar-bonyldichlororhodate(I) salts (equation 241).226... 

The di-(TPPDS)239 and tri-sulfonated phosphines (116) (Scheme 8) (TPPTS)239 are also known, the latter being the most widely used water-solubilizing phosphine ligand, as of 2002. The synthesis of (116) is ostensibly similar to that of (115), although more recently it has been shown that addition of orthoboric acid to the sulfonation mixture reduces the amount of tertiary phosphine oxide side products.240 This general sulfonation procedure has been used for the preparation of various ditertiary (e.g., (117))241 242 and chiral sulfonated phosphines (e.g., (118)).241,243-245 Carboxylic acid- and carboxylate-modified phosphines (e.g., (119) and (120)) are also known.246,247... 

There is an extensive chemistry of tertiary phosphine rhodium(III) complexes. However, there are comparatively few complexes of monodentate tertiary arsines, although the complexes of ditertiary arsines are more numerous. There are virtually no tertiary stibine complexes. The two main preparative routes to the complexes described in this section are (i) direct reaction pf the ligands with rhodium trichloride, which usually yields trichloro complexes and (ii) oxidative addition to rhodium(I) tertiary phosphine complexes, which gives rise to more diverse products of the type [RhXYZ(PRj) ], Metathetical reactions on the complexes prepared by either method (i) or (ii) have been used to prepare most of the remaining compounds. 

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