
TY  - JOUR
A1  - Colton, R 
A1  - Farthing, RH 
A1  - Knapp, JE 
T1  - Carbonyl halides of the Group VIII transition metals. IV. Halocarbonyls and halocarbonyl anions of rhodium(III) and rhodium(I)
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1970
VL  - 23
IS  - 7
SP  - 1351
EP  - 1358
KW  - 
UR  - https://doi.org/10.1071/CH9701351 
N2  - Both rhodium trichloride and tribromide are easily carbonylated and subsequently reduced by refluxing formic acid-hydrohalic acid mixture to give almost quantitative yields of the rhodium(1) halocarbonyl anions [Rh(CO)2X2]- (X = Cl,Br). It has been shown that the reaction proceeds by the intermediate formation of the rhodium(111) halocarbonyl anions [Rh(CO)X5]2- followed by slow reduction to the rhodium(1) complexes. Evaporation of the respective solutions leads to almost quantitative recovery of the new rhodium(111) halocarbonyls Rh(CO)X3 and the well known rhodium(1) compounds [Rh(C0)2X]2.   Iododicarbonylrhodium(1) could not be isolated by this method and in fact the only products which could be isolated were triiodocarbonylrhodium(111), Rh(CO)I3, and its corresponding anion; this shows that although the carbonylation reaction had occurred the subsequent reduction did not proceed. In solution the rhodium(1) complexes [Rh(C0)2X2]- oxidize to give [Rh(CO)X5]2-. Caesium salts of these rhodium(111) anions are readily isolated, but addition of caesium salts to the rhodium(1) solutions did not give the expected Cs[Rh(CO)2X2] but instead the octahedral complexes Cs2[Rh(C0)2(H2O)X3]. All of these changes in composition and oxidation state have been followed in solution, as well as in the isolated solid products, by infrared spectroscopy. 
ER  -

