Photochemistry of (η3‑allyl)Ru(CO)3X Precursors for Photoassisted Chemical Vapor Deposition

Quantum yields for loss of a single CO ligand in alkane solutions were determined for the (η3-allyl)­Ru­(CO)3X complexes, where X = Cl, Br, I. The three complexes had similar quantum yields at λexc = 254 nm, while the quantum yields obtained at 313 nm followed a trend of ΦBr > ΦCl > ΦI. A wavelength dependence of the quantum yields in the order Φ254 < Φ313 < Φ334 was observed for the iodo complex. Very low levels of luminescence were observed for the compounds, demonstrating that radiative decay of the excited states was not competitive with nonradiative processes, including photochemical reactions. Excited states were assigned as MLCT or LF on the basis of solvatochromism and DFT studies.