Diiodo rhodium complexes

If nitrosyl bromide is allowed to react with hydrated rhodium trichloride and PPh3 in ethanol, the mixed chlorobromo complex is obtained (equation 301).13 3 When [RhCl(PPh3)3] is the substrate the dibromo complex is formed (equation 302). This complex can also be obtained from rhodium tribromide, JV-methyl-JV-nitrosotoluene-p-sulfonamide and PPh3. Replacement of PPh3 by other tertiary phosphines permits analogous dibromo complexes to be prepared (cf. equation 299). Another source of the triphenylphosphine complex is [Rh(NO)2Br] . The diiodo complex can be obtained from a similar reaction mixture containing Lil (equation 304).1293... 

Analogs of the dichloro complex are prepared by a variety of methods, many of which are specific for single compounds. The dibromo complexes can be prepared using nitrosyl bromide or from A-methyl-iV-nitrosotoluene-4-sulfonamide and rhodium tribromide. Replacement of the tribromide by the trichloride and an alkali metal iodide gives diiodo complexes (equations 50 and 51). 

---