Highly oxidizing excited states of Re and Tc complexes.
Like the Re analogue, the ligand-to-metal charge transfer (LMCT) excited-state of [Tc(dmpe)3]2+ (dmpe is bis-1,2-(dimethylphosphino)ethane) is luminescent in solution at room temperature. Surprisingly, both [M(dmpe)3]2+* species have extremely large excited-state potentials (ESPs) as oxidants-the highest for any simple coordination complex of a transition metal. Furthermore, this potential is available using a photon of visible light (calculated for M = Re(Tc); E1/2* = +2.61(2.52) V versus SCE; lambdamax = 526(585) nm). Using a Rehm-Weller analysis with a series of aromatic hydrocarbons as electron-transfer quenchers, E1/2(Re2+*/Re+) has been determined to be 2.58 V, in good agreement with the calculated value. Both [M(dmpe)3]2+* species are quenched by chloride ion and both can function as excited-state oxidants in water solution.
Del Negro
Andrew S
AS
Pacific Northwest National Laboratory, Richland, WA 99352, USA.
Seliskar
Carl J
CJ
Heineman
William R
WR
Hightower
Sean E
SE
Bryan
Samuel A
SA
Sullivan
B Patrick
BP
D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D012211:Rhenium / Q000737:chemistry*; D013667:Technetium / Q000737:chemistry*
D009942:Organometallic Compounds; D012211:Rhenium; D013667:Technetium