PICOSECOND TRANSIENT GRATING STUDY OF THE ROTATIONAL DIFFUSION OF A RUTHENIUM COMPLEX IN SOLUTION

The rotational diffusion time of ruthenium(II)-bis(2,2'-bipyridine) (2,2'-biquinoleine) has been measured in polar solvents of different viscosity. The rotational dynamics can be explained in terms of the Stokes-Einstein-Debye hydrodynamics theory under stick boundary condition by considering the rotating body as a prolate spheroid enclosing the complex. This overestimates the intrinsic molecular volume by a factor of 1.5. The difference can be accounted for by solvent molecules intercalated in the interligand space and stabilized by electrostatic interaction with the charge of the metal atom.