SYNTHESIS, STABILITY AND REACTIVITY OF CATIONIC CARBONYL-COMPLEXES OF RHODIUM(I)

Trans-[RhCl(CO)L2] (L = PPh3, AsPh3 or PCy3) react with AgBF4 in CH2Cl2 to give the novel species [Rh(CO)L2]+ [BF4]-.nCH2Cl2 (n = 1/2 or 1 1/2) (1-3), which we believe to be stabilised by weak solvent interaction. The corresponding stibine compound cannot be isolated by the same process, instead [Rh(CO)2(SbPh3)3]+[BF4]-(7) is formed when the reaction is carried out in the presence of CO. When reactions designed to prepare [Rh(CO)L2]+[BF4]- are performed in the presence of CO, or [Rh(CO)L2]+[BF4]- complexes are reacted with CO, [Rh(CO)2L2]+[BF4]- (L = PPh3, AsPh3 or PCy3) (4-6) are formed. lf Me2CO is used as solvent in the preparation of [Rh(CO)L2]+[BF4]- (L = PPh3 or AsPh3), then the products are the four-coordinate [Rh(CO)L2-(Me2CO)]+[BF4]- (8,9) species. The complexes have been characterised by i.r., P-31 and H-1 n.m.r. spectroscopy and elemental analyses.