3340
Guo et al.: Infrared spectroscopy of ONCCNO
TABLE IV. Estimated geometry of ONCCNO.a
TABLE V. The C–C bond lengths ͑r ͒ in simple organic molecules.
0
Parameter
Structure I
Structure II
Molecule
Method
rC–C ͑Å͒
b
1.1923c
1.1730c
1.3329d
180.0°
1.536a
rNO/Å
rCN/Å
rCC/Å
ЄONC
ЄNCC
1.1994
1.1679
1.3337
180.0°
180.0°
H C–CH3
IR
MW
MW
IR
MW
IR
3
b
b
H C–CwN
1.4582
3
d
c
H C–CwNO
1.442
1.389
1.382
1.337
3
d
NwC–CwN
HCwC–CwN
H CvCH
e
180.0°
f
2
2
a
g
Linear framework assumed.
rS bond lengths from HCNO, Ref. 11.
See text for details.
ONC–CNO
HCwCH
IR
IR
1.3329
1.20862
b
h
c
d
a
e
Bond length calculated using experimental rotational constant.
Reference 13.
Reference 14.
Reference 15.
Reference 12.
Reference 16.
b
f
Reference 17.
c
g
h
This work.
Reference 18.
d
Indications from the ab initio calculations, and compari-
sons with similar molecules, suggest that the important CC
bond is quite short. The single B value obtained in this work
achieved. For example, the possibility of quasilinear behav-
ior cannot be ruled out at this stage of the analysis. We plan
additional experiments to record spectra of the much weaker
bending vibrational modes as well as combination bands.
This work will help assign the numerous hot bands that we
have measured and will provide information on the missing
modes of gerade symmetry.
8
is insufficient to provide this parameter without some as-
sumptions about the CN and NO bond lengths. One approach
to this problem is to use the known CN and NO bond lengths
in the parent HCNO molecule,11 and assuming a linear struc-
ture, extract the CC value from the rotational constant ͑B0͒
determined in this work. Table IV, structure I, shows the
structure of ONCCNO, predicted by this method. This, of
course, assumes that the CN and NO bond lengths are trans-
ferable from HCNO.
ACKNOWLEDGMENTS
We thank the Natural Science and Engineering Research
Council of Canada ͑NSERC͒ for the support of this research.
T.P. thanks NSERC for the award of a NATO Science Fel-
lowship. Partial support was provided by the Petroleum Re-
search Fund and the NASA laboratory astrophysics program.
A possible improvement on this method is to see how a
computational method ͓MP3͑full͒/6-31G*͔8 performs for
both HCNO and ONCCNO, and then ‘‘correct’’ the CN and
NO values and apply them to ONCCNO. With these ‘‘re-
fined’’ CN and NO bond lengths, the mutual effect of back-
to-back CNO groups should be taken into account, and, us-
ing the experimental rotational constant, a value for the CC
bond length is obtained. This assumes that the differences
between the CN and NO bond lengths in HCNO and ONC-
CNO are predicted correctly by the MP3 method. Table IV,
structure II, shows the revised values for ONCCNO. This
structure which takes into account the interaction of the two
CNO groups, indicates that the NO bond length has slightly
decreased, while the CN bond length has slightly increased,
in accord with expectations based on a more delocalized
framework.
1
2
W. Steinkopf and B. J u¨ rgens, J. Prakt. Chem. 83, 453 ͑1911͒.
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3
4
͑
a͒ N. E. Alexandrou and D. N. Nicolaides, J. Chem. Soc. C, 2319 ͑1969͒;
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¨
A. G u¨ l, A. I. Okur, A. Cihan, N. Tan, and O. Bekaroglu, J. Chem. Res. ͑S͒,
¨
9
͑
0 ͑1986͒; ͑d͒ S. Serin and O. Bekaroglu, Z. Anorg. Allg. Chem. 496, 197
¨
1983͒; ͑e͒ Y. G o¨ k and O. Bekaroglu, Synth. React. Inorg. Met.-Org.
Chem. 11, 621 ͑1981͒; ͑f͒ V. Ahsen, E. Musluoglu, A. G u¨ rek, A. G u¨ l, O.
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¨
and S. Serin, Synth. React. Inorg. Met.-Org. Chem. 18, 975 ͑1988͒; ͑h͒ Y.
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Ch. Grundmann and P. Gr u¨ nanger, The Nitrile Oxides ͑Springer-Verlag,
5
6
7
Both the directly transferred CN and NO lengths, and the
corrected values, lead to the result that the CC bond length is
about 1.333 Å, approximately the same as that in ethylene,
H CCH , a molecule of known double bond character. Table
New York, 1971͒.
G. Maier and J. H. Teles, Angew. Chem. 99, 152 ͑1987͒; Angew. Chem.
Int. Ed. Engl. 26, 155 ͑1987͒.
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dyne Frequency Measurements ͑NIST Special Publication 821, Washing-
ton DC, 1991͒.
2
2
8
9
V shows CC bond lengths for a range of molecules. An im-
portant observation is that the experimental CC bond length
in cyanogen, NC-CN is 1.389 Å,12 already much shorter than
a typical CC single bond and we anticipate that this will
decrease upon adding terminal oxygen atoms ͑compare
H CCN and H CCNO in Table V͒. We note that
10
R. A. Toth, J. Opt. Soc. Am. B 8, 2236 ͑1991͒.
11
͑a͒ H. K. Bodenseh and M. F. Winnewisser, Z. Naturforsch. A 24, 1973
͑1969͒; ͑b͒ B. P. Winnewisser, M. F. Winnewisser, and F. Winther, J. Mol.
Spectrosc. 51, 65 ͑1974͒.
A. G. Maki, J. Chem. Phys. 3, 3193 ͑1965͒.
W. J. Lafferty and E. K. Plyler, J. Chem. Phys. 37, 2688 ͑1962͒.
C. C. Costain, J. Chem. Phys. 29, 864 ͑1958͒.
H. K. Bodensen and K. Morgenstern, Z. Naturforsch 25a, 150 ͑1970͒.
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59, 116 ͑1976͒.
3
3
MP3͑full͒/6-31G* calculations for NCCN predict CC to be
12
1
.393 Å, with similar calculations for ONCCNO predicting
13
8
1
1
1
1
4
5
6
7
CC to be 1.361 Å. The inference from this is that the CC
length in ONCCNO is at least 0.03 Å less than that in
NCCN.
Clearly, experimental and theoretical studies on this mol-
ecule have a long way to go before a full characterization is
18
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J. Chem. Phys., Vol. 103, No. 9, 1 September 1995
128.82.252.58 On: Tue, 23 Dec 2014 01:47:22
Guo, Bujin
