Journal of Physical Chemistry A, Vol.122, No.6, 1550-1559, 2018
Unusually Short-Lived Solvent-Dependent Excited State in a Half Sandwich Ru(II) Complex Induced by Low-Lying (MC)-M-3 States
A ruthenium complex with a half-sandwich geometry ([(p-cymene)Ru(Cl)(curcuminoid)]) was synthesized, characterized, and investigated regarding its ultrafast photophysics. These photophysical investigations of the complex revealed a weak and short-lived emission from the initially populated (MLCT)-M-1 state and solvent-dependent photo induced dynamics, where the secondarily populated (MC)-M-3 state is stabilized by nonpolar solvents. Overall the decay of the (3)dd-MC state to the ground state is completed within picoseconds. This short excited-state lifetime is in stark contrast to the typically observed long-lived (MLCT)-M-3 states with lifetimes of nanoseconds or microseconds in unstrained, octahedral ruthenium complexes but is in good agreement with the findings for distorted octahedral complexes. This is pointing to the half-sandwich geometry as a new and easy approach to study these otherwise often concealed dd states.