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Photobehavior of copper(I) compounds. Role of copper(I)-phosphine compounds in the photosensitized valence isomerization of norbornadiene

Journal Article · · J. Am. Chem. Soc.; (United States)
DOI:https://doi.org/10.1021/ja00509a031· OSTI ID:5854071

The valence isomerization of norbornadiene to quadricyclene can be photosensitized with high quantum efficiency by certain copper(I)-phosphine compounds. Sensitization yields in the presence of Cu(PPh/sub 3/)/sub 2/BH/sub 4/ and Cu(PPh/sub 2/Me)/sub 3/BH/sub 4/ attain limiting values of 0.76 and 0.54, respectively, at high norbornadiene concentrations. In contrast, Cu(diphos)BH/sub 4/ (diphos is 1,2-bis(diphenylphosphino)ethane), which contains a bidentate phosphine ligand, is decidely less effective. The mechanism of sensitization by these copper(I)-phosphine compounds is fundamentally different from that exhibited by simple cuprous salts in that no ground-state coordination to the metal center occurs. A pathway involving the bimolecular interaction of the photoexcited Cu(I) compound with a ground-state norbornadiene molecule is better able to accommodate the available data. Electronic absorption and emission studies reveal some interesting differences between the spectral properties of effective vs. noneffective sensitizers.

Research Organization:
Univ. of Georgia, Athens
OSTI ID:
5854071
Journal Information:
J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:15; ISSN JACSA
Country of Publication:
United States
Language:
English