135366-33-5Relevant academic research and scientific papers
Ground- and excited-state infrared spectra of an azacrown-substituted [(bpy)Re(CO)3L]+ complex: Structure and bonding in ground and excited states and effects of Ba2+ binding
Lewis, Jared D.,Towrie, Michael,Moore, John N.
, p. 3852 - 3864 (2008)
Ground- and excited-state infrared spectra are reported for a [(bpy)Re I(CO)3L]+ complex (bpy = 2,2′-bipyridine) in which L contains an azacrown ether that is linked to Re via an amidopyridyl group. Ground-state band assignments are made with the aid of spectra from model complexes in which a similar electron-donating dimethylamino group replaces the azacrown, in which an electron-donor group is absent, and from the L ligands, in conjunction with DFT calculations. Picosecond time-resolved IR (TRIR) spectra in the v(CO) region show bands characteristic of a metal-to-ligand charge-transfer (MLCT) excited state, [(bpy?-)Re II(CO)3L]+, from the complex in which an electron-donor group is absent, whereas those from the azacrown complex show bands of an MLCT state evolving into those characteristic of a ligand-to-ligand charge-transfer (LLCT) excited state, [(bpy?-)Re I(CO)3(L?+)]+, formed upon intramolecular electron transfer. Picosecond TRIR spectra of the azacrown complex in the fingerprint region show strong L ligand bands that indicate that significant charge redistribution occurs within this ligand in the MLCT state and that decay as the LLCT state forms. Picosecond TRIR spectra obtained when Ba2+ was complexed to the azacrown show bands of only an MLCT state at all times up to 2 ns, consistent with the presence of Ba2+ inhibiting electron transfer from the azacrown N atom to form the LLCT state, and the positions of the bands in the fingerprint region provide direct evidence for the proposal that charge redistribution within the L ligand induces Ba 2+ release from the azacrown in the MLCT state.
