II (C4a, C4b, C8a, C9, C10, C10a), and III (C4b, C5, C6, C7,
C8, C8a) are 2.7(2) and 3.8(2)Њ for I–II, 4.5(2) and 6.0(2)Њ for
I–III, and 2.3(2) and 2.3(2)Њ for II–III in 1 and 2, respectively.
Fig. 5 shows a superposition of 1 and 2 drawn by fitting atoms
C4a, C8a, C9, and C10 using crystallographic coordinates and
3 F. D. Lewis, E. L. Burch and C. L. Stern, J. Phys. Org. Chem., 1997,
0, 525.
1
4
C. Balo, F. Fernández, C. Gonzáles and C. Lopéz, Spectrochim.
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5
28
MacroModel software.
6 B. R. Dent and B. Halton, Aust. J. Chem., 1986, 39, 1789.
1
13
1
The H and C{ H} NMR spectral parameters of 1 and 2 are
7 R. M. Letcher, Org. Magn. Reson., 1981, 16, 220.
1
1
8 F. A. Beland and R. G. Harvey, J. Am. Chem. Soc., 1976, 98,
given in Table 4. H– H coupling constants in C D (not pre-
6
6
4
963.
sented here) were within 0.02 Hz of the values in CDCl . The
3
9
R. Laatikainen, J. Magn. Reson., 1988, 78, 127.
1
1
H– H coupling constants are comparable to those presented in
1
0 D. Neuhaus and M. Williamson, The Nuclear Overhauser Effect
in Structural and Conformational Analysis, VCH Publishers Inc.,
New York, 1988, Chap. 7.
4,7,9
the literature.
The signs of couplings were adopted from
work of Laatikainen on the spin–spin couplings of naph-
9
5
thalene. The sign of J
(assumed positive) was evaluated
11 T. Kottke and D. Stalke, J. Appl. Crystallogr., 1993, 26, 615.
H4,H5
1
2 M. S. Lehmann and F. K. Larsen, Acta Crystallogr., Sect. A, 1974,
0, 580.
with PERCH by changing it to negative, but no effect on the
spectrum was seen. The couplings between the phenanthrene
protons are almost the same in 1 and 2. The largest difference is
3
1
3 MSC/AFC Diffractometer Control Software. Version 4.3.0.
Molecular Structure Corporation, The Woodlands, TX 77381,
USA, 1992.
0
.06 Hz. The substituent does not affect the coupling constants.
For nuclei that are far from the point of substitution, the H
1
14 TEXSAN: Single Crystal Structure Analysis Software, Molecular
chemical shifts are comparable in 1 and 2. When the tert-butyl
group is replaced by a phenyl group the resonance of H8
exhibits a 0.41 ppm shift to lower frequency, while the reson-
ance of H10 shifts by only 0.14 ppm. The resonance of carbon
C8 is shifted by 1.67 ppm and that of C10 by 4.75 ppm. The
aromatic ring current has an opposite effect on the carbons and
the protons. The rotation around the axis C9–S causes simul-
taneous reorientation of the phenyl group, which is especially
pronounced as the coplanar conformation is approached. The
stronger shielding of H8 than of H10 could be explained if the
phenyl group, in general, is facing toward H8, as in the solid
state. Why the carbons show reversed sensitivity to the ring
current remains unexplained.
In the NOE difference experiment, irradiation of the tert-
butyl protons of 2 yielded an 8% increase in the area of H8 and
a 7% increase in H10. This would suggest that, on average, the
tert-butyl protons lie at equal distances from H8 and H10. This
also indicates an approximately 90Њ torsion angle C10–C9–S–
C12. In the case of compound 1, H8 and H10 were irradiated
separately. The area of protons H13/H15 increased in both
experiments, but the magnitude could not be established. This
would suggest a perpendicular orientation of the substituent at
sulfur relative to the phenanthrene plane.
Structure Corporation, The Woodlands, TX 77381, USA, 1993.
1
5 M. C. Burla, M. Camalli, A. Altomare, G. Cascarano, C.
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17 G. M. Sheldrick, SHELXTL PC, Release 4.1, Siemens Analytical
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8 H. Friebolin, Basic One- and Two-Dimensional NMR Spectro-
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9 G. E. Martin and A. S. Zektzer, Two-Dimensional NMR Methods
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0 D. Neuhaus and M. Williamson, The Nuclear Overhauser Effect
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2
2
2
1 R. Laatikainen, J. Magn. Reson., 1991, 92, 1.
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4 H. D. Flack, Acta Crystallogr., Sect. A, 1983, 39, 876.
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6 M. I. Kay, Y. Okaya and D. E. Cox, Acta Crystallogr., Sect. B, 1971,
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2
2
2
2
3
Acknowledgements
8 W. C. Still, F. Mohamadi, N. G. J. Richards, W. C. Guida,
M. Lipton, R. Liskamp, G. Chang, T. Hendrickson, F. DeGunst
and W. Hasel, MacroModel V. 4.5, Department of Chemistry,
Columbia University, New York.
The support of Acta Chemica Scandinavica toward presenting
part of this paper at the 16th Nordic Structural Chemistry
Meeting at Sigtuna, Sweden, in 1998 is gratefully acknow-
ledged.
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