The charge distribution on metal-bonded cyclopentadienyl rings from infrared intensities

The IR intensities of the C-H vibrational modes of a hydrocarbon fragment b onded to a metal atom are a useful probe to evaluate the charge distributio n on the fragment. The values of R, the ratio of the overall C-H bending an d C-H stretching IR intensities of the cyclopentadienyl ligand, are reporte d for several organometallic complexes containing the eta(5)-C5H5-M unit. T he parameter R is related to several properties of the complexes, such as t he ionic charge, the nature of the metal and of the ancillary ligands, the C-H bending force constant and to the solid-state structure. (C) 2000 Elsev ier Science S.A. All rights reserved.