Abstract
The i.r. spectra of a number of π-cyclopentadienyl-metal carbonyl complexes have been studied in the range 4000–550 cm.–1 and with the aid of partially deuteriated derivatives of (π-C5H5)Mn(CO)3, [(π-C5H5)Mo(CO)3]2, and (π-C5H5)Mo(CO)2NO, it has been possible to assign satisfactorily vibrations of the cyclopentadienyl ring.