We have measured the first gas-phase electronic absorption spectra of (δ6-C6H6)Cr(CO)3, (η6-C6H5Cl)Cr(CO)3, and (β6-C6H5CH3)Cr(CO)3. Low-resolution, 200-cm-1, spectra show intense (92000 L/(mol cm)) absorption features extending into the vacuum ultraviolet region indicating the existence of at least five different electronic states with energies below 61 000 cm-1. Our low-resolution data suggest that only one of those states shifts appreciably with arene substitution. We compare these results with solution-phase spectra and other data. At higher resolution, 40 cm-1, our data suggest that the onset of detectable absorption is lower in energy for (i;6-C6H6)Cr(CO)3than for both (7/6-C6H5Cl)Cr(CO)3and (η6-C6H5CH3)Cr(CO)3. The fine structure of this transition may be correlated with the well-known photolability of the CO ligands. We discuss these new data in the light of our earlier multiphoton spectroscopy results on these molecules.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry