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Ohhara T, Uekusa H, Ohashi Y, et al. Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. III. Photoracemization of 1-cyanoethyl cobaloxime complexes. Acta Crystallogr B. 2001;57:551-9doi: 10.1107/s0108768101006838.
Ohhara, T., Uekusa, H., Ohashi, Y., Tanaka, I., Kumazawa, S., & Niimura, N. (2001). Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. III. Photoracemization of 1-cyanoethyl cobaloxime complexes. Acta crystallographica. Section B, Structural science, 57551-9. https://doi.org/10.1107/s0108768101006838
Ohhara, T, et al. "Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. III. Photoracemization of 1-cyanoethyl cobaloxime complexes." Acta crystallographica. Section B, Structural science vol. 57 (2001): 551-9. doi: https://doi.org/10.1107/s0108768101006838
Ohhara T, Uekusa H, Ohashi Y, Tanaka I, Kumazawa S, Niimura N. Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. III. Photoracemization of 1-cyanoethyl cobaloxime complexes. Acta Crystallogr B. 2001 Aug;57:551-9. doi: 10.1107/s0108768101006838. Epub 2001 Jul 25. PMID: 11468382.
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Acta Crystallogr B. 2001 Aug;57:551-9. doi: 10.1107/s0108768101006838. Epub 2001 Jul 25.

Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. III. Photoracemization of 1-cyanoethyl cobaloxime complexes.

Acta crystallographica. Section B, Structural science

T Ohhara, H Uekusa, Y Ohashi, I Tanaka, S Kumazawa, N Niimura

Affiliations

  1. Department of Chemistry and Materials Science, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551, Japan.

PMID: 11468382 DOI: 10.1107/s0108768101006838

Abstract

The H atoms bonded to the chiral C atoms (stereogenic center) of the 1-cyanoethyl groups in two cobalt complexes, [(R)-1-cyanoethyl]bis(dimethylglyoximato)(pyridine)cobalt(III) (2) and [(R,S)-1-cyanoethyl]bis(dimethylglyoximato)(piperidine)cobalt(III) (3), were replaced with D atoms, such as Co--C*D(CH(3))CN. The crystals of the two cobalt complexes were irradiated with a xenon lamp for 72 h and 27 d, respectively. The unit-cell dimensions were gradually changed with retention of the single-crystal form. The crystal structures after irradiation were determined by neutron diffraction. In each crystal the chiral 1-cyanoethyl group of one of the two crystallographically independent molecules was partly inverted to the opposite configuration, whereas that of the other molecule kept the original configuration. The C*--D bond in the inverted group was completely conserved in the process of the inversion of the chiral alkyl group. This suggests that the inversion of the chiral 1-cyanoethyl group proceeds with the rotation of the cyanoethyl radical after the Co--C bond cleavage by photo-irradiation so that the opposite side of the radical faces the Co atom. This is followed by recombination of the Co--C bond to form the inverted 1-cyanoethyl group.

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