Luminescence and excitation spectroscopy of ruthenocene.

The luminescence and excitation spectra of the perdeuterated and the protonated ruthenocene have been carefully investigated. The electronic origins are at 21 459 cm-1 and at 21 390 cm-1 for the perdeuterated and protonated crystals, respectively. The two observed luminescence progressions in the metal-ring stretch a’1 (D5h notation) in the perdeuterated crystal are separated by 155 cm-1 compared to the 165–170 cm-1 reported for the protonated compound. The metal-ring stretch frequency is reduced to 318 cm-1 in the perdeuterated crystal from the 333 cm-1 found for the protonated compound. In both crystals the observed doubling of the vibrational progression is due to a false origin based on a skeletal bending mode δ(ring-Ru-ring) which transforms as e1 in D5h. This mode is split by 7–8 cm-1 via the low site symmetry (Cs) in the crystal. The excitation spectrum of both compounds shows only a single progression in the metal-ring stretch. This frequency is reduced by 16% in the excited state for both the protonated and the perdeuterated crystal. Deuteration increases the lifetime from 127 μs to 990 μs at 1.5 K. [ABSTRACT FROM AUTHOR]