COMMUNICATIONS
T. Preiss, H. P. Reisenauer, B. A. Hess, Jr., L. J. Schaad, J. Am. Chem.
Soc 1994, 116, 2014 ± 2018.
[4] R. W. Hoffmann, R. Schüttler, Chem. Ber. 1975, 108, 844 ± 855.
[5] We thank Prof. E.-U. Würthwein, Universität Münster, for drawing
our attention to this fact in 1993 (MP2/6 ± 31G** calculations,
unpublished results).
[6] a) K. Tanaka, M. Yoshimine, J. Am. Chem. Soc. 1980, 102, 7655 ± 7662;
b) W. J. Bouma, R. H. Nobes, L. Radom, C. E. Woodward, J. Org.
Chem. 1982, 47, 1869 ± 1875; c) M. Yoshimine, J. Chem. Phys. 1989, 90,
378 ± 385.
[7] R. Hochstrasser, J. Wirz, Angew. Chem. 1989, 101, 183 ± 185; Angew.
Chem. Int. Ed. Engl. 1989, 26, 805.
[8] Gaussian 94, Revision B.1, M. J. Frisch, G. W. Trucks, H. B. Schlegel,
P. M. W. Gill, B. G. Johnson, M. A. Robb, J. R. Cheeseman, T. Keith,
G. A. Petersson, J. A. Montgomery, K. Raghavachari, M. A. Al-
Laham, V. G. Zakrzewski, J. V. Ortiz, J. B. Foresman, J. Cioslowski,
B. B. Stefanov, A. Nanayakkara, M. Challacombe, C. Y. Peng, P. Y.
Ayala, W. Chen, M. W. Wong, J. L. Andres, E. S. Replogle, R.
Gomperts, R. L. Martin, D. J. Fox, J. S. Binkley, D. J. Defrees, J.
Baker, J. P. Stewart, M. Head-Gordon, C. Gonzalez, J. A. Pople,
Gaussian, Inc., Pittsburgh PA, 1995.
[9] The isotopomer [D2]1 was prepared according to ref. [4] from
quadricyclanone and nonadeuterotrimethylsulfoxonium chloride.
[10] a) G. Maier, H. P. Reisenauer, T. Sayraç, Chem. Ber. 1982, 115, 2192 ±
2201; b) G. Maier, H. P. Reisenauer, T. Sayraç, Chem. Ber. 1982, 115,
2202 ± 2213.
[11] For a review on the oxirene problem, see a) E. Lewars, Chem. Ber.
1983, 83, 519 ± 534; see also b) E. Lewars, J. Mol. Struct. (Theochem)
1996, 360, 67 ± 80, and references therein; c) G. Maier, C. Schmidt,
H. P. Reisenauer, E. Endlein, D. Becker, J. Eckwert, B. A. Hess, Jr.,
L. J. Schaad, Chem. Ber. 1993, 126, 2337 ± 2352; reference [6].
[12] W. Sander, G. Bucher, S. Wierlacher, Chem. Rev. 1993, 93, 1583 ± 1621.
[13] If CH2 is replaced by SiH2 the CO complex H2Si ´ CO is calculated to
be the global minimum on the CH2OSi potential-energy surface and
can be isolated in a cryogenic matrix: G. Maier, H. P. Reisenauer, H.
Egenolf in Organosilicon Chemistry IVÐFrom Molecules to Materials
(Eds: N. Auner, J. Weis), VCH, Weinheim, in press.
identification of isonitroso hydrogen (2) in solid argon at
10 K.
For the generation of HON (2) the same method can be
used, which was employed by Jacox and Milligan 15 years ago
to produce and to identify HNO (1) IR spectroscopically in an
argon matrix.[2] Thus, hydrogen atoms are generated by
exposing a H2/Ar mixture to a microwave discharge and
deposited together with a NO/Ar mixture on a 10 K cold
spectroscopic window. Under these conditions a NO radical
and a hydrogen atom can recombine to form HNO (1). In the
meantime we know that HON (2) is also generated within this
process in a small amount. Alternatively one can produce the
same products by passing a mixture of NO, H2, and argon
(ratio: 1:2:250) or of H2, N2, O2, and argon (ratio: 4:1:1:500)
through a microwave discharge.
Independent of the chosen method of generation we found
strong IR absorptions of HNO (1) and small bands, which we
assign to HON (2). The identification of 2 is based mainly on
the investigation of the photochemistry of the already known
HNO (1) isomer. Moreover, further products (NH, N2O,
N2O2 , N2O3, HNO2, NO2, OH, H2O, HO2 , CO, CO2) could be
observed in various amounts. In analogy with the photo-
isomerization of nitrosyl cyanide (ONCN) to isonitrosyl
cyanide (NOCN),[3] the thermodynamically more stable
nitroso hydrogen (1) was converted into the less stable
isonitroso hydrogen (2). During irradiation of HNO (1) in
solid argon at 10 K with monochromatic light of the wave-
length l 313 nm, the HNO bands at 2715.1, 1562.2, and
1
1504.3 cm decrease, while two new absorptions arise at
1
3467.2 and 1095.6 cm , which we assign to HON (2). At the
1
same time the NO band (1871.4 cm ) increases. If the
[14] G. Vacek, J. M. Galbraith, Y. Yamaguchi, H. F. Schaefer III, R. H.
Nobes, A. P. Scott, L. Radom, J. Phys. Chem 1994, 98, 8660 ± 8665.
wavelength is changed to l 254 nm the HON absorptions
decrease, while the HNO bands increase. During this second
irradiation the NO band continues to grow. All these
observations point to a photochemical equilibrium between
HNO (1) and HON (2), which is presumably reached by the
Isonitroso Hydrogen (Hydroxy Nitrene,
HON)**
Günther Maier,* Hans Peter Reisenauer,
and Michael De Marco
Dedicated to Professor Heinrich Nöth
on the occasion of his 70th birthday
dissociation of the two isomers into NO radicals and H atoms.
The position of the equilibrium depends on the wavelength of
light used for the irradiation. The increase of the NO
concentration during the photoisomerization is caused by
cage escape of H atoms, which are rather mobile even at 10 K
in solid argon.[4]
Irradiation with very short (248, 193, 185 nm) and long
(> 330 nm) wavelengths does not lead to any observable
isomerization. The identification of isonitroso hydrogen (2) is
based essentially on the comparison of the experimental and
calculated IR spectra. Figure 1 shows a difference spectrum,
which documents the photoisomerization between 1 and 2.
Furthermore the corresponding calculated IR spectra (Gaus-
sian package of programs)[5] are included for comparision. In
addition the D- (Figure 2) and 15N-isotopomers of HON (2)
have been investigated. All results (BLYP[6] and QCISD/6-
311 G**) are compiled in Table 1.
The importance of nitroso hydrogen HNO (1) for combus-
tion, atmospheric chemistry, astrophysics, and particularly
theoretical chemistry is demonstrated in a multitude of papers
published on this topic.[1] According to the results of some
theoretical studies the existence of isonitroso hydrogen HON
(2) besides HNO (1) is anticipated, but to the best of our
knowledge there is no experimental evidence for that. Herein
we describe the first matrix isolation and IR-spectroscopic
[*] Prof. Dr. G. Maier, Dr. H. P. Reisenauer, Dipl. -Chem. M. De Marco
Institut für Organische Chemie der Universität
Heinrich-Buff-Ring 58, D-35392 Giessen (Germany)
Fax: (49)641-99-34309
[**] This work was supported by the Fonds der Chemischen Industrie and
the Deutsche Forschungsgemeinschaft.
108
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