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Investigation of Unstable Molecules and Free Radicals by Rotational Spectroscopy.

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vapor pressure isotope effect whereas they are fully excited a t
room temperature and thus d o not contribute.
Lecture at Heidelberg (Germany) on February 28th, 1967 [VB 74 IE]
German version: Angew. Chem. 79,728 (1967)
ment of the equilibrium are suppressed by internal hydrogen
bridges. For instance, the 2-methoxycarbonyl compound ( I )
is a true nitrosophenol both in the solid state and in benzene
or dioxane.
[*I Prof. Dr. H.Wolff and Dr. A. Hopfner
Physikalisch-Chemisches Institut der Universitait
Tiergartenstr.
69 Heidelberg (Germany)
Developments of Fuel Cells
By W. Vielstich [*I
General Motors recently exhibited a bus (Electrovan) driven
by a 32 kW H2/02 battery (Union Carbide Inc.) operating
an alternating current motor. Disadvantages of this experimental model are the tanks containing liquid hydrogen and liquid oxygen (danger of explosion) and the high
cost of the noble metals in the hydrogen electrode. A 200 kW
battery constructed by Firma ASEA, Sweden, for propulsion of a submarine, utilizes ammonia and liquid air;
the ammonia is first cracked in a reformer and the hydrogen
obtained is fed to skeleton nickel electrodes.
The triangular potential scan method is useful for study of
the fundamental principles. In the region between initial
H2- and 02-evolution, the electrode potential varies linearly
with time in a periodic manner. In this way, the experimental
electrode is reproducibly reactivated during measurement.
The nature of the intermediate product in the oxidation of
formic acid is of particular interest. By comparing the
charge needed for oxidation of the adsorbed intermediate
with the amount of carbonate formed (determined by
titration) it was shown that one electron is consumed per
carbon atom. This result suggests that COOH radicals are
the intermediates, rather than CO.
The composition and structure o f the catalyst have a great
effect o n the dehydrogenation of methanol and formate in
alkaline electrolytes. At the same electrode potential the
anodic current densities for methanol (uncharged particles)
and formate (charged particles) on various catalysts (e.g. Pt,
Pd, and Pt/Pd alloys) differ by more than one order of
magnitude.
Fuel cell batteries based on methanol/air and formate/air
and incorporating these catalysts have already been tested as
energy sources in signal installations and TV relay stations.
Fuel monocells are superior to the usual dry batteries
in respect of greater capacity, constant discharge potential,
ease of recharging, and better storage life. Monocells are
constructed o n the following principles: The lid of the
monocell is fitted with a cylindrical carbon diffusion electrode
with an air inlet and a metal terminal. The cell also contains
a cylindrical fuel electrode and fuel electrolyte (20 ml 4 M
C H 3 0 H + 9 N KOH). After discharge (e.g. 50 mA, 0.6 v,
240 h, 12 Ah), the element can be regenerated simply by
renewal o f the electrolyte.
Lecture at Gottingen (Germany) on February 23rd, 1967 [VB 75 IEI
German version: Angew. Chem. 79, 726 (1967)
On the other hand, in the solid state the 3-methoxycarbonyl
compound (2) is a quinone oxime with intermolecular
hydrogen bridges. The oxime group is in the anti-position to
the methoxycarbonyl group, as it is also in other quinone
4-oximes having a substituent on C-3 [21.
5-Methoxy-2-nitrosophenol exists in a brownish-green and
in a n orange form. Burawoy 131 concluded from the electronic
spectra of this compound in various solvents that an equilibrium exists between the nitrosophenol with a n internal
bridge and a quinone oxime with a n internal bridge. Bartindale[4] proved that the orange form in the solid state is a
quinone oxime with intramolecular bridges and anti-relation
of the oxime group to the quinone oxygen atom, which is in
agreement with the behavior of 1,4-quinone oximes [21. By
means of IR and electron band spectra of the two solid forms
and in various solvents, aided by the dependence of the
spectra on the hydrogen ion concentration and on temperature, it has been found that, in carbon tetrachloride, there is
a n o-nitrosophenol with an internal bridge but that in polar
solvents there is a n equilibrium between the nitrosophenol
with an internal bridge, the mesomeric ion, and the quinone
oxime with intermolecular bridges (cf., however 9.
A 1,2-quinone oxime with internal bridge is to be expected
if a substituent in the second neighboring position to the
oxime group prevents the movement of that group from the
syn-position to the quinone oxygen, even though this type of
substitution favors the quinone oxime structure. Such a case
exists in 1,2-naphthoquinone I-oxime; here also polar solvents lead to partial fission of the internal hydrogen bridge,
so that the naphthoquinone with internal bridge is in equilibrium with the mesomeric ion and 1-nitroso-2-naphthol.
Lecture at Hanover (Germany) on February 23rd 1967
[VB 71 IEJ
German version: Angew. Chem. 79, 692 (1967)
[*] Dr. H. Uffmann
Institut fur Organische Chemie der Technischen Hochschule
Callinstr. 46
3 Hannover (Germany)
[l] E. Havinga and A . Schors, Rec. Trav. chim. Pays-Bas 69, 457
(1950); H . Uffmann,Tetrahedron Letters 1966, 4631.
Z. Naturforsch., in press.
[2] H . U’mann,
[3] A . Burawoy et al., J. chem. SOC.(London) 1955, 3727.
141 G. W. R. Bartindale et ai., Acta crystallogr. 12, 111 (1959)
[ 5 ] C. Romers, Acta crystallogr. 17, 1287 (1964).
Investigation of Unstable Molecules and Free
Radicals by Rotational Spectroscopy
[*I Prof. Dr. W.Vielstich
Institut fur physikalische Chemie der Universitlt
Wegelerstr. 12
53 Bonn (Germany)
IntramolecularHydrogen Bridges in Nitrosophenols
By H. U#mann~*I
Tautomeric equilibria of the type p-nitrosophenol 2 1,4benzoquinone 4-monoxime are established via a n intermediate mesomeric ion which can itself play a considerable
part in the equilibrium[ll. Formation of the ion and achieve-
714
By M . Winnewisser[*l
The millimeter and submillimeter region of the electromagnetic spectrum is a field of molecular spectroscopy that
is rich but almost undeveloped. Because of their short
wavelength [lo mm (30000 MHz) to 1 mm (300000 MHz)
these waves can be collimated and focused by a combination
of waveguides, horns, and Teflon lenses, which permits
the use of large glass or quartz absorption cells for spectroscopy of unstable molecules and gaseous radicals [I].
The gases to be studied a-e contained in a cylindrical glass
cell (diameter 10 cm, length 100 cm), which is placed in the
path of the millimeter radiation. A system of gas discharge
Angew. Chem. internat. Edit.
1 Vol. 6 (1967)
No. 8
tubes, connected directly to the cell, serves for production
of free radicals.
Using such a spectrometer, Winnewisser, Sustry, and GurdyL2l first obtained the millemeter spectrum of sulfur monoxide (electron ground state 3C) in the gas discharge products
of SO2 and studied the magnetic properties of the radicalf31.
In the gas discharge product of H2S the relatively unstable
H& is formed from the SH radical by secondary reactions [41,
similarly to the production of H202 from OH radicals.
Formation of disulfane was proved by the rotational spectrum
in the millimeter region. The disulfane rotational spectrum is
the first 1-type spectrum of an almost symmetrical top
with x = -0.999985. This shows that the dipole moment is
perpendicular to the symmetry axis of the inertia tensor and
parallel to the twofold symmetry axis, thus proving the chain
structure of HSSH with C2 symmetry. Analysis of the millimeter spectrum I51 and electron-diffraction measurements f61
yielded the preliminary structure ( I ) for disulfane.
Electron Spin Resonance Studies of Bridged
Annulenes
By F. Gerson [*I
A model of a ten- or fourteen-membered Tc-electron perimeter
can be used for interpretation of the ESR spectra of radical
ions of the bridged annulenes ( I ) to ( 4 ) " 1 .
dlSSI=2.055 8
dlSH1.1.3458
$lHSSl=91"45'
0 =90"36'
Fulminic acid is another unstable molecule whose structure
in the free gaseous state was hitherto unknown. Beck and
FeZdl[71 proved that it has the nitrile oxide form by means
of its IR spectrum. The microwave spectrum between 10000
and 50000 MHz indicates a linear molecule [81. Measurement
of the various isotope combinations showed the atomic
bonding HCNO and the preliminary structural parameters
indicated in formula (2).
The lowest antibonding (+a) and the highest bonding orbita
(+b) of the two perimeters are twofold degenerate. They can
be classified as 0% and +a-, and as +b+ and qb-, respectively.
Here plus denotes symmetrical and minus antisymmetrical
with respect to a plane that passes through two opposed centres in the perimeter and is perpendicular to the plane of the
perimeter. Bridging of the system results in lifting of the
degeneracy of +% and
on the one hand and of +b+ and
+b- on the other.
In the radical anions of the bridged [lO]annulenes ( I ) and (3)
the unpaired electron occupies the antisymmetrical orbital
+a-, which thus lies lower than
However, in the radical
anions of the bridged [14]annulenes (2) and (4) the unpaired electron is in the symmetrical orbital +a+. which is
here more stable than +a-.
+-.
In the radical cation, which can also be prepared from compound (4), there is a n unpaired electron in the symmetrical +b+ orbital, which thus has a higher energy than
+b-.
L
m
11608
/21
'
12088
Lecture at Kiel (Germany) on February ZOth, 1967
[VB 76 IEl
German version: Angew. Chem. 79, 727 (1967)
[*I Dr. M. Winnewisser
Technische Hochschule
Hertzstr. 16, Bau 35 I1
75 Karlsruhe (Germany)
111 R . Kewley, K . V. L. N . Sastry, M . Winnewisser, and W . Gordy,
J. chern. Physics 39, 2856 (1963).
[2] M . Winnewisser, K. V. L. N . Sastry, and W . Gordy, Bull.
Amer. physic. SOC.9, 488 (1964).
[3] M. Winnewisser, K . V . L. N . Sastry, R . L. Cook, and W . Gordy, J. chem. Physics 41, 1687 (1964).
[4] G. Winnewisser, M. Winnewisser, and W . Gordy, Bull. Arner.
physic. SOC.11, 312 (1966).
[5] G. Winnewisser, M. Winnewisser, and W . Gordy, unpublished.
[6] M . Winnewisser and J . Haase, unpublished.
I71 W . Beck and K. Feldl, Angew. Chem. 78, 746 (1966); Angew.
Chern. internat. Edit. 5 , 722 (1966).
[8] M . Winnewisser and H. K. Bodenseh, unpublished.
Angew. Chem. internat. Edit. 1 Vul. 6 (1961) / No. 8
These results permit conclusions to be drawn about the
nature and direction of the effect exerted by the bridges on
the ir-electron systems in compounds ( I ) to (4). Considered
in conjunction with the geometry of the compounds, they
lead to the following conclusions: In ( I ) and (2) the effect
of CH2, 0, and N bridges is mainly inductive and electronrepelling. In (4), however, this effect may perhaps be accompanied by hyperconjugation between the cr-electrons of
the butane bridges and the x-electrons of the perimeter.
Finally, in (3) the mesomeric and electron-donating effect
of the central nitrogen atom plays the most important part.
Lecture at Marburg on April 21st, 1967
[VB 78 IE1
German version: Angew. Chem. 79, 693 (1967)
[*] Doz. Dr. F. Gerson
Laboratoriurn fur Organische Chemie
Universitgtsstrasse 6
CH-8006 Ziirich (Switzerland)
[I] Cf. also F. Gerson, E. Heilbronner, N . Joop, and H . Zimmermann, Helv. chim. Acta 46, 1940 (1963); F. Gerson and J. D. W.
van Voorst, ibid. 46, 2257 (1963); F. Gerson, E. Heilbronner, and
V. Boekelheide, ibid. 47, 1123 (1964); F. Gerson, E. Heilbronner,
W . A. Boll, and E. Vogel, ibid. 48, 1494 (1965); F. Gerson:
Hochauflosende ESR-Spektroskopie, dargestellt anhand aromatischer Radikal-Ionen, Verlag Chemie, Weinheim 1967, in
press, Chapter 2, Section 5.
715
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