Labelling studies to determine product formation from reactions of CO and hydrogen catalysed by Ru clusters and Rh complexes

Reaction of CO with hydrogen in the presence of [Ru-3(CO)(12)], KI and N-methylpyrrolidone produces small amounts of methanol under mild conditions. Using D-2 the methanol is CD3OD confirming that it is a product of CO hydrogenation. In the presence of added H2O, CH (x) D1-y OH/D (y=0-3) are produced. Carrying out the same reaction in the presence of MeI water and RhCl3 center dot xH(2)O (x=3-4) produces ethanoic acid in a slow reaction which continues for at least 64 h. The effects of different reaction parameters are discussed and labelling using (CH3I)-C-13 shows that some of the ethanoic acid originates from sources other than MeI whilst labelling with D-2, CD3I, and/or D2O suggest that some originates from CO and H-2. Electrospray mass spectrometry and high pressure infra-red spectroscopic studies show that the main species present in catalytic solutions are [HRu3(CO)(11)](-), [HRu4(CO)(13)](-) and [Ru(CO)(3)I-3](-) for methanol carbonylation, [Ru(CO)(3)I-3](-) and [RhI2(CO)(2)](-) for ethanoic acid production. A reaction carried out in the absence of [Ru-3(CO)(12)] gave similar results to a reaction in which it was added, suggesting that the entire process may be catalysed by rhodium complexes alone.