Vibrational spectra and structure of ?staircase? carbonyl ?-complexes of transition metals

Abstract

FTIR spectra have been studied for “staircase” cyclopentadienyl complexes containing two or three metal carbonyl fragments bound by the metal-carbon bond Cp(CO)2Fe-CpmMn(CO)3 (1), Cp(CO)2Fe-CpmFe(CO)2CH2Ph (2), Cp(CO)2Fe-Cpm(CO)2Fe-CpmMn(CO)3 (3), Cp(CO)2Mo-Cpm(CO)2Fe-CpmMn(CO)3 (4), Cp(CO)3W-Cpm(CO)2Fe-CpmMn(CO)3 (5), Cp(CO)2Fe-Cpm(CO)2Fe-BmCr(CO)3 (6), Cr(CO)3Bm-CpmFe(CO)2CH2Ph (7), where Cp = η5-C5H5, Cpm = η1∶η5-C5H4, Bm = η1∶η6-C6H5. Temperature-dependent FTIR spectra were measured inn-pentane solutions over a wide temperature range and in the low-temperature solid matrices of argon and nitrogen. Rotamers, formed due to rotation about the metal-carbon σ-bond, were found in solutions and matrices. A molecular mechanics calculation of1 proved the possibility of such rotation.