ELUCIDATION OF THE REVERSIBLE CARBON-MONOXIDE REACTIONS OF A PARAMAGNETIC RHODIUM(II) COMPLEX

Coordination of carbon monoxide to the rhodium(II) ether-phosphine complex [Rh(tmpp)2][BF4]2 1 [tmpp = tris(2,4,6-trimethoxyphenyl)phosphine] initiates a redox reaction to produce the rhodium(III) complex [Rh(tmpp)2][BF4]3 2 and the dicarbonyl rhodium(I) species [Rh(tmpp)2(CO)2][BF4] 3; the latter readily loses a CO ligand to form [Rh(tmpp)2(CO)][BF4] 4 which enters into a second redox reaction with 4 to regenerate the original rhodium(II) radical 1.