Insertion reactions of t-Bu(η5-C5H5)Fe(CO)2

The complex t-Bu(η 5 -C 5 H 5 )FE(CO) 2 has been treated with triphenylphosphine in refluxing THF to produce t-BuCO(η 5 -C 5 H 5 )Fe(CO)(PPh 3 ). The large steric bulk of the t-butyl group suggests that this reaction should be faster than the reaction involving the methyl group, and a kinetic investigation illustrates this to be the case. The same steric bulk predicts that the reaction with SO 2 should be slow, and indeed we have been unable to effect the related SO 2 insertion reaction. Attempts to prepare the corresponding t-Bu(η 5 -C 5 H 5 )W(CO) 3 led to formation of the related isobutyl complex.