SYNTHESIS AND CATALYTICAL APPLICATIONS OF COBALT AND IRON CARBONYLS -HYDROFORMYLATION AND RELATED REACTIONS

The results of research on the chemistry of metal carbonyls performed between 1951 and 1993 in Veszprem have been summarized. More than 80 n ew cobalt and iron carbonyl derivatives have been prepared, most of wh ich are sulphur-containing cluster complexes. Among these we find the first paramagnetic metal carbonyl cluster [Co-3(CO)(9)S], the first mi xed-metal carbonyl cluster containing a heteroatom [Co2Fe(CO)(9)S], an d the first metal carbonyl containing the SO group (which is not stabl e as a free molecule) as a ligand [Fe-3(CO)(9)S(SO)]. The principal ai m of the research on catalytic reactions was the clarification of the mechanism of olefin hydroformylation catalyzed by cobalt carbonyls. Th is was made possible by the fact that the model compounds of the suppo sed intermediates of the reaction could be prepared in a pure state. A ll steps of the catalytic cycle have been investigated separately and it was found that the mechanism is partially radical in character and it is not the same for purely aliphatic and aryl-aliphatic olefins, re spectively. The mechanism of the effect by which the temperature and t he partial pressure of CO influence the isomeric composition of the al dehydes formed was clarified. It was shown that under the conditions o f industrial hydroformylation the reaction runs mainly over very react ive intermediates which cannot be isolated nor even detected spectrosc opically and therefore their role in the reaction is supported only by the kinetics of the individual steps of the catalytic cycle. Furtherm ore it was found that iron-, chromium-, molybdenum-, and tungsten carb onyl [M(CO)(n); M = Fe, n = 5; M = Cr, Mo, W, n = 6] form in the prese nce of bases active catalysts for the homogeneous hydrogenation of C = O and C = N bonds.