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Long‐Lived Excited States of Zwitterionic Copper(I) Complexes for Photoinduced Cross‐Dehydrogenative Coupling Reactions
Author(s) -
Wang Bin,
Shelar Deepak Prakash,
Han XianZhu,
Li TingTing,
Guan Xiangguo,
Lu Wei,
Liu Kun,
Chen Yong,
Fu WenFu,
Che ChiMing
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201405356
Subject(s) - copper , excited state , photochemistry , coupling (piping) , chemistry , materials science , physics , atomic physics , organic chemistry , metallurgy
Abstract Four heteroleptic copper(I) complexes containing phenanthroline and monoanionic nido ‐carborane‐diphosphine ligands have been prepared and structurally characterized by various spectroscopic techniques and X‐ray diffraction. These complexes exhibit intense absorptions in the visible range and excited‐state lifetimes on the microsecond scale. Their application in visible‐light‐induced cross‐dehydrogenative coupling reactions was investigated. Preliminary studies showed that one of the four copper(I) complexes is an efficient catalyst for photoinduced oxidative CH functionalization using oxygen as oxidant. Furthermore, α‐functionalized tertiary amines were obtained in good‐to‐excellent yields by light irradiation ( λ >420 nm) of a mixture of our Cu I complex, tertiary amines, and a variety of nucleophiles (nitroalkane, acetone, or indoles) under aerobic conditions. Electron paramagnetic resonance measurements provided evidence for the formation of superoxide radical anions (O 2 −⋅ ) rather than singlet oxygen ( 1 O 2 ) during these photocatalytic reactions.