Carbon-13 isotopic exchange in pentacarbonyliron

Previous nonclusive experimental results to answer the question of intra- vs intermolecular exchange in Fe(CO)/sub 5/ are surveyed. Results of experiments using 92 percent enriched Fe(/sup 13/CO)/sub 5/ and Fe(/sup 12/CO)/sub 5/ with only natural abundance of /sup 13/C are described. The spectral data indicated that the intermolecular exchange is very slow without a catalyst to definitely prove that the CO ligand exchange between axial and equatorial positions follows an intra- rather than an intermolecular path. The high contribution of spin-rotation interaction to the relaxation mechanism is also cited as evidence of an intramolecular exchange path. (BLM)