LIGAND EFFECTS IN SYNTHESIS OF THE COMPLEXES C1RH(PO)P-SIMILAR-TO-O, [RH(PO)(2)][BPH(4)] AND [RH(COD)(PO)][BPH(4)]

The behaviour of the rhodium(I) complexes [(mu-Cl)Rh(COE)2]2 (1, COE = cyclooctene) and [(mu-Cl)Rh(COD)]2 (6, COD = 1,5-cyclooctadiene) towards a series of ether-phosphines of the type R2PCH2CH2OCH3 (R = (t)Bu (2a), (i)Pr (2b), Cy (2c), Ph (2d)) was examined. Complex 1 reacts with 2b,c to give pure RhCl(P O)(P approximately O) (4b,c, P O: eta2-bonded O,P ligand; P approximately O: eta1-P-bonded O,P ligand). In contrast, treatment of 1 with 2d predominantly yields [(mu-Cl)Rh(P approximately O)2]2 (3d), which may be photochemically converted into 4d. In the presence of NaBPh4, the reaction of 1 with 2b,c results in the formation of the bis(chelate) complex cis-[Rh(P O)2][BPh4] (5b,c). 5d, however, is only accessible by Cl- abstraction from 4d. Treatment of 6 with 2a-c and NaBPh4 affords [(COD)Rh(P O)][BPh4] (7a-c), whereas 2d gives [(COD)Rh(P approximately O)2][BPh4] (8d).