Irradiated single crystals of sodium perfluorosuccinate show ESR spectra at 300°K characteristic of a single CO2CF2CFCO2 radical, but on cooling below 130°K the spectra show that motion has been frozen out and that the radicals occupy two crystallographically nonequivalent positions. The hyperfine interaction tensors for one α‐ and two β‐fluorine atoms of each radical have been determined at 77°K and compared with those of the 300°K radical. The average of the hyperfine tensors for the two radicals at 77°K is shown to be close to the observed tensor for the single radical at 300°K. Motional averaging by oscillation about the central C–C bond is indicated. Crystals of sodium perfluorosuccinate irradiated and observed at 77°K without warming up show the presence of a single radical with a somewhat different orientation in the crystal lattice than the room temperature radical or either of the radicals obtained on cooling the room temperature radical to 77°K.

1.
J. R.
Morton
,
Chem. Rev.
64
,
453
(
1964
).
2.
O. H.
Griffith
,
J. Chem. Phys.
41
,
1093
(
1964
), and references cited within.
3.
R. J.
Cook
,
J. R.
Rowlands
, and
D. H.
Whiffen
,
Mol. Phys.
7
,
31
(
1964
).
4.
R. J.
Lontz
and
W.
Gordy
,
J. Chem. Phys.
37
,
1357
(
1962
).
5.
M. T.
Rogers
and
D. H.
Whiffen
,
J. Chem. Phys.
40
,
2662
(
1964
).
6.
R. J.
Lontz
,
J. Chem. Phys.
45
,
1339
(
1966
).
7.
F.
Srygley
and
W.
Gordy
,
Bull. Am. Phys. Soc.
11
,
204
(
1966
).
8.
R. W.
Fessenden
and
R. H.
Schuler
,
J. Chem. Phys.
43
,
2704
(
1965
).
9.
K.
Toriyama
and
M.
Iwasaki
,
J. Phys. Chem.
73
,
2919
(
1969
).
10.
M. T.
Rogers
and
L. D.
Kispert
,
J. Chem. Phys.
46
,
3193
(
1967
).
11.
G. T.
Trammell
,
H.
Zeldes
, and
R.
Livingston
,
Phys. Rev.
110
,
630
(
1958
).
12.
H.
Shimizu
,
J. Chem. Phys.
42
,
3603
(
1965
).
13.
J. A.
Nelder
and
R.
Mead
,
Comput. J.
7
,
308
(
1965
);
R. Ernst (personal communication).
14.
Reported at the Southeastern Magnetic Resonance Conference, September 1969, Huntsville, Ala.
15.
Several references to articles outlining the full theory are included in Ref. 5.
16.
The original program MAGNSPEC was written by M. Kopp and J. Mackey at Mellon Institute, Pittsburgh, Pa.; an expanded and revised version has been written for the UNIVAC 1108 at University of Alabama.
17.
L. D. Kispert (unpublished results).
18.
We are indebted to D. H. Whiffen, University of Newcastle, for this suggestion.
19.
H. S.
Gutowsky
and
C. H.
Holm
,
J. Chem. Phys.
25
,
1228
(
1956
).
20.
E. W.
Stone
and
A. H.
Maki
,
J. Chem. Phys.
37
,
1326
(
1962
).
21.
K.
Morokuma
,
J. Am. Chem. Soc.
91
,
5412
(
1969
).
22.
W. A.
Sheppard
,
J. Am. Chem. Soc.
87
,
2410
(
1965
).
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