The hydrolysis of (-C6H6)Cr(-C6F5CO2C2H5): an unexpected decarboxylation

The attempted basic hydrolysis of the ester sandwich compound (C 6 H 6 )Cr(C 6 F 5 CO 2 Et) did not yield the expected carboxylic acid but instead produced (C 6 H 6 )Cr(C 6 F 5 H) in good yield together with traces of (C 6 H 6 )Cr(C 6 HF 4 OMe). Attempts to trap a benzyne intermediate were unsuccessful and the mechanism of decarboxylation is discussed in terms of internal chelation at the chromium centre.