Solvent-free organometallic migratory insertion reactions

Migratory insertion reactions of organometallic complexes have been shown to occur in the absence of solvent and, more significantly, between solid reagents. Reaction between eta(5)-C5H5)M(CO)(3)Me (M = Mo, W) or (,eta(5)-C5H5)Fe(CO)(2)Me and PPh3 (no solvent) took place at temperatures between 40 and 90 degreesC and gave the products (eta(5)-C5H5)M(CO)(2)(PPh3)COMe and (eta(5)-C5H5)Fe(CO)(PPh3)COMe in moderate to good yield (60-99%). The Mo and W complexes reacted in the solid state when T < 80 degreesC. The decarbonylation of (eta(5)-C5H5)MO(CO)(2)(PPh3)COMe to yield (eta(5)-C5H5)Mo(CO)(2)(PPh3)Me also occurred in the solid state (120 degreesC). Reaction of (eta(5)-C5H5)MO(CO)(3)Me with a range of ligands, L (L = PPh3, P(p-MeOC6H4)(3), PCy3, PEt3, AsPh3, POPh3, P(OEt)(3); 1:1 reagent ratio, 90 degreesC, 15 min), in the absence of solvent gave (eta(5)-C5H5)Mo(CO)(2)(L)COMe (7-100% yield) and, on extended reaction, (eta(5)-C5H5)Mo(CO)(2)(L)Me in varying yields. A kinetic study of the solid-state reaction between (eta(5)-C5H5)Mo(CO)(3)Me and PPh3 yielded rate constants, e.g. k = 5.18 x 10(-5)s(-1) (Mo:p = 1:10; 50 degreesC), which compares with the literature solution data in toluene (k = (0.8-2.5) X 10(-5) s(-1), 50 degreesC) using similar metal to ligand ratios. The data are consistent with a pseudo-first-order reaction in the presence of PPh3. Diffusional effects on the reaction rate are detected at low temperature and low PPh3 ratios.