Structure, motion, and exchange coupling of 15NO2/15NO2 radical pairs occupying adjacent solvent cavities of α-HNIW, a nitramine hydrate

Journal of the American Chemical Society

Volumn 119, Issue 21, 1997, Pages 4826-4833

  Ryzhkov, Lev R ^a,b   McBride, J Michael ^a  

^a YALE UNIVERSITY   (United States)

^b TOWSON UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

2,4,6,8,20 HEXANITROHEXAAZATETRACYCLODODECANE; NITRAMINE; NITRIC OXIDE; NITRO DERIVATIVE; RADICAL; UNCLASSIFIED DRUG;

ARTICLE; CRYSTAL STRUCTURE; DECOMPOSITION; ELECTRON SPIN RESONANCE; PHOTOLYSIS; STRUCTURE ANALYSIS;

EID: 0030995616     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9631615     Document Type: Article

References (35)

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12. At 10 K, kT is about 20 cal/mol. The largest magnetic energy is typically the Zeeman splitting of 1 cal/mol at X-band, and more relevant magnetic interactions, such as zfs and hfs, are 10-1000 times smaller. When the ground state is a triplet, EPR intensities are insensitive to the magnitude of large J values.
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20. Warming from 80 to 195 K simplified the spectra slightly by removing traces of material with slightly larger splitting than pairs A-C discussed below. This might represent very small amounts of ab or a′b pairs, see Discussion.
21. Less that 4% of any decaying signal intensity reappears in a surviving signal.
22. Experimental, differences, and simulated a-and b-axis spectra for pairs B and C are available in the Supporting Information as Figures 2s-5s.
23. A′ peaks that would be denoted by open squares at high field are obscured by the A peaks and are omitted from Figure 4.
24. Crystal orientations, line positions, and output of the refinement programs are available in the Supporting Information.
25. Weltner, W. Magnetic Atoms and Molecules, 2nd ed.; Dover Publications Inc.: New York, 1989; Chapter II, pp 104-108.
26. The source of these g shifts is unclear. ZFS is far too small to shift the average line position.
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28. 1 nuclear states would be about an order of magnitude smaller than for the αβ and βα nuclear states, and usually it would be much smaller still. The approximation may contribute to the difference between observed and calculated line positions in Figures 4 and 5.
29. Each solid line corresponds to two states whose energies are not affected by taking antisymmetrized combinations.
30. The same value of J was used to give a qualitatively satisfactory simulation of the position and intensity of the J lines of one of the asymmetric units plotted in Figure 4 for all phases of rotation. See Figure 1s in the Supporting Information.
31. 2 in a variety of radical pairs.
32. 16 Center-to-center distances of the cavities are 9.49 Å for aa′ and 8.14 Å for ab and a′b. (31) Some pairs have unfavorable conformations for concerted fragmentation.
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34. Analogous one-electron coupling is several orders of magnitude smaller through-space than through intervening alkane molecules. Curtiss, L. A.; Naleway, C. A.; Miller, J. R. J. Phys. Chem. 1993, 97, 4050.
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