Solvent-Free Organometallic Migratory Insertion Reactions
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Date
2003-03-10
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Abstract
Migratory insertion reactions of organometallic complexes have been shown to occur in
the absence of solvent and, more significantly, between solid reagents. Reaction between
(η5-C5H5)M(CO)3Me (M ) Mo, W) or (η5-C5H5)Fe(CO)2Me and PPh3 (no solvent) took place
at temperatures between 40 and 90 °C and gave the products (η5-C5H5)M(CO)2(PPh3)COMe
and (η5-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 °C. The decarbonylation of (η5-C5H5)-
Mo(CO)2(PPh3)COMe to yield (η5-C5H5)Mo(CO)2(PPh3)Me also occurred in the solid state
(120 °C). Reaction of (η5-C5H5)Mo(CO)3Me with a range of ligands, L (L ) PPh3, P(p MeOC6H4)3, PCy3, PEt3, AsPh3, POPh3, P(OEt)3; 1:1 reagent ratio, 90 °C, 15 min), in the
absence of solvent gave (η5-C5H5)Mo(CO)2(L)COMe (7-100% yield) and, on extended reaction,
(η5-C5H5)Mo(CO)2(L)Me in varying yields. A kinetic study of the solid-state reaction between
(η5-C5H5)Mo(CO)3Me and PPh3 yielded rate constants, e.g. k ) 5.18 × 10-5 s-1 (Mo:P ) 1:10;
50 °C), which compares with the literature solution data in toluene (k ) (0.8-2.5) × 10-5
s-1, 50 °C) 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