Controlling Photoisomerization Reactivity Through Single Functional Group Substitutions in Ruthenium Phosphine Sulfoxide Complexes

We report the crystallography,
emission spectra, femtosecond pump–probe
spectroscopy, and density functional theory computations for a series
of ruthenium complexes that comprise a new class of chelating triphenylphosphine
based ligands with an appended sulfoxide moiety. These ligands differ
only in the presence of the para-substitutent (e.g.,
H, OCH3, CF3). The results show a dramatic range
in photoisomerization reactivity that is ascribed to differences in
the electron density of the phosphine ligand donated to the ruthenium
and the nature of the excited state.