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Ohhara T, Harada J, Ohashi Y, et al. Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. II. 3-1 photoisomerization of a cobal-oxime complex. Acta Crystallogr B. 2000;56:245-53doi: 10.1107/s0108768199012008.
Ohhara, T., Harada, J., Ohashi, Y., Tanaka, I., Kumazawa, S., & Niimura, N. (2000). Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. II. 3-1 photoisomerization of a cobal-oxime complex. Acta crystallographica. Section B, Structural science, 56245-53. https://doi.org/10.1107/s0108768199012008
Ohhara, et al. "Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. II. 3-1 photoisomerization of a cobal-oxime complex." Acta crystallographica. Section B, Structural science vol. 56 (2000): 245-53. doi: https://doi.org/10.1107/s0108768199012008
Ohhara T, Harada J, Ohashi Y, Tanaka I, Kumazawa S, Niimura N. Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. II. 3-1 photoisomerization of a cobal-oxime complex. Acta Crystallogr B. 2000 Apr;56:245-53. doi: 10.1107/s0108768199012008. PMID: 10794278.
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Acta Crystallogr B. 2000 Apr;56:245-53. doi: 10.1107/s0108768199012008.

Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction. II. 3-1 photoisomerization of a cobal-oxime complex.

Acta crystallographica. Section B, Structural science

Ohhara, Harada, Ohashi, Tanaka, Kumazawa, Niimura

Affiliations

  1. Department of Chemistry and Materials Science, Tokyo Institute of Technology, O-okayama, Japan.

PMID: 10794278 DOI: 10.1107/s0108768199012008

Abstract

Single crystal neutron diffraction analysis of photo-exposed (3-cyanopropyl-d2(alpha,alpha))-[(R)-1-phenylethylamine-d11]bis(dimethylglyoximato-d14)cobalt(III) was carried out in order to clarify the mechanism of the crystalline-state photoisomerization of the 3-cyanopropyl group bonded to the Co atom in some cobaloxime complexes. Before irradiation the two H atoms bonded to the C1 atom of the 3-cyanopropyl group were exchanged with the D atoms such as --CH2CH2CD2CN. On exposure to a xenon lamp, the cell dimensions of the crystal were gradually changed. After 7 d exposure the change became insignificantly small. The structure was analyzed by neutron diffraction. The 3-cyanopropyl group was transformed to the 1-cyanopropyl group such as --CD(CN)C(H1/2,D1/2)2CH3 with retention of the single-crystal form. This indicates that one of the D atoms bonded to C1 migrates to either position bonded to C2. The other atoms of the complex remained unchanged. These results indicate that photoisomerization proceeded in two steps: the 3-cyanopropyl group was isomerized to the 2-cyanopropyl group in the first place and then the 2-cyanopropyl group was transformed to the 1-cyanopropyl group. Moreover, it was made clear that the second-step isomerization was irreversible, since one of the D atoms was retained. The disordered structure at C2 is estimated to be caused by the interconversion between the 1-cyanopropyl group produced and its dehydrogenated olefin after the photoisomerization.

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