1 research outputs found
Fe<sup>II</sup> Hexa <i>N</i>‑Heterocyclic Carbene Complex with a 528 ps Metal-to-Ligand Charge-Transfer Excited-State Lifetime
The iron carbene complex [Fe<sup>II</sup>(btz)<sub>3</sub>](PF<sub>6</sub>)<sub>2</sub> (where btz
= 3,3′-dimethyl-1,1′-bis(<i>p</i>-tolyl)-4,4′-bis(1,2,3-triazol-5-ylidene))
has been
synthesized, isolated, and characterized as a low-spin ferrous complex.
It exhibits strong metal-to-ligand charge transfer (MLCT) absorption
bands throughout the visible spectrum, and excitation of these bands
gives rise to a <sup>3</sup>MLCT state with a 528 ps excited-state
lifetime in CH<sub>3</sub>CN solution that is more than one order
of magnitude longer compared with the MLCT lifetime of any previously
reported Fe<sup>II</sup> complex. The low potential of the [Fe(btz)<sub>3</sub>]<sup>3+</sup>/[Fe(btz)<sub>3</sub>]<sup>2+</sup> redox couple
makes the <sup>3</sup>MLCT state of [Fe<sup>II</sup>(btz)<sub>3</sub>]<sup>2+</sup> a potent photoreductant that can be generated by light
absorption throughout the visible spectrum. Taken together with our
recent results on the [Fe<sup>III</sup>(btz)<sub>3</sub>]<sup>3+</sup> form of this complex, these results show that the Fe<sup>II</sup> and Fe<sup>III</sup> oxidation states of the same Fe(btz)<sub>3</sub> complex feature long-lived MLCT and LMCT states, respectively, demonstrating
the versatility of iron <i>N-</i>heterocyclic carbene complexes
as promising light-harvesters for a broad range of oxidizing and reducing
conditions