双核氰基桥联混合价配合物中金属到金属电荷转移激发态的时间分辨光谱学

Time-resolved spectroscopy of the metal-to-metal charge transfer excited state in dinuclear cyano-bridged mixed-valence complexes.

作者信息

Macpherson Brendan P, Bernhardt Paul V, Hauser Andreas, Pagès Stéphane, Vauthey Eric

机构信息

Department of Chemistry, University of Queensland, Brisbane, Queensland 4072, Australia.

出版信息

Inorg Chem. 2005 Jul 25;44(15):5530-6. doi: 10.1021/ic0506512.

DOI:10.1021/ic0506512

PMID:16022552

Abstract

Visible pump-probe spectroscopy has been used to identify and characterize short-lived metal-to-metal charge transfer (MMCT) excited states in a group of cyano-bridged mixed-valence complexes of the formula LCo(III)NCM(II)(CN)(5), where L is a pentadentate macrocyclic pentaamine (L(14)) or triamine-dithiaether (L(14S)) and M is Fe or Ru. Nanosecond pump-probe spectroscopy on frozen solutions of L(14)Co(III)NCFe(II)(CN)(5) and L(14S)Co(III)NCFe(II)(CN)(5) at 11 K enabled the construction of difference transient absorption spectra that featured a rise in absorbance in the region of 350-400 nm consistent with the generation of the ferricyanide chromophore of the photoexcited complex. The MMCT excited state of the Ru analogue L(14)Co(III)NCRu(II)(CN)(5) was too short-lived to allow its detection. Femtosecond pump-probe spectroscopy on aqueous solutions of L(14)Co(III)NCFe(II)(CN)(5) and L(14S)Co(III)NCFe(II)(CN)(5) at room temperature enabled the lifetimes of their Co(II)-Fe(III) MMCT excited states to be determined as 0.8 and 1.3 ps, respectively.

摘要

可见泵浦 - 探测光谱已被用于识别和表征一组通式为[LCo(III)NCM(II)(CN)(5)]-的氰基桥联混合价配合物中的短寿命金属 - 金属电荷转移（MMCT）激发态，其中L是五齿大环五胺（L(14)）或三胺 - 二硫醚（L(14S)），M是Fe或Ru。在11K下对[L(14)Co(III)NCFe(II)(CN)(5)]-和[L(14S)Co(III)NCFe(II)(CN)(5)]-的冷冻溶液进行纳秒级泵浦 - 探测光谱，能够构建差分瞬态吸收光谱，其特征在于在350 - 400nm区域吸光度增加，这与光激发配合物的铁氰化物发色团的产生一致。Ru类似物[L(14)Co(III)NCRu(II)(CN)(5)]-的MMCT激发态寿命太短，无法检测到。在室温下对[L(14)Co(III)NCFe(II)(CN)(5)]-和[L(14S)Co(III)NCFe(II)(CN)(5)]-的水溶液进行飞秒级泵浦 - 探测光谱，能够确定它们的Co(II)-Fe(III) MMCT激发态寿命分别为0.8和1.3皮秒。