Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
Inorg Chem. 2023 Feb 6;62(5):2128-2134. doi: 10.1021/acs.inorgchem.2c03779. Epub 2023 Jan 26.
Irradiation of cobalt metallocenes at the ligand-to-metal charge transfer energies results in the labilization of the cyclopentadienyl-cobalt bond and radical release. The cyclopentadienyl radical is detected by electron paramagnetic resonance (EPR) spectroscopy using a spin trap and can also be chemically trapped using hydrogen-atom-donating reagents. This reaction presents a new photochemical method of generating new cobalt complexes or of forming cyclopentadienyl cobalt(I) species that are active for catalytic [2 + 2 + 2] cyclotrimerization reactions. More importantly, these results also show that cobaltocene should not be considered as a photostable redox reagent under many conditions, including those relevant to photovoltaics or photocatalysis.
钴茂金属在配体到金属电荷转移能量下的辐照导致环戊二烯基-钴键的不稳定和自由基释放。使用自旋捕获剂通过电子顺磁共振（EPR）光谱检测环戊二烯基自由基，也可以使用提供氢原子的试剂通过化学捕获。该反应提供了一种新的光化学方法来生成新的钴配合物或形成对[2 + 2 + 2]环三聚反应具有活性的环戊二烯基钴（I）物种。更重要的是，这些结果还表明，在许多条件下，包括与光伏或光催化相关的条件下，二茂钴不应被视为光稳定的氧化还原试剂。
