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Bromyl Cation [BrO2]+.

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Bromyl Cation, [Br02]+ [**I
Procedure
By Eberhard Jacobyl
Dedicated to Professor Josef Goubeau on the occasion of his
75th birthday
The co-condensation of highly reactive components at low
temperatures"] offers a means of moderating otherwise uncontrollable reactions and of directing them along preparatively
interesting pathways. This approach has now permitted the
first generation and stabilization of the bromyl cation as the
fluoroantimonate ( 2 a ) by slow warming of a co-condensate
of bromyl fluoride ( 1 )I2] and an excess of antimony pentafluoride, prepared at -196"C, to room temperature in a high
vacuum.
Br02F(3.1g,24mmol)fromastoragevessel cooled to -7°C
and SbF5(28.3g, 130mmol)are simultaneously passed through
two concentric tubes into the lower part of a 2-1 stainless
steel vessel cooled with liquid nitrogen, where they condense.
Throughout the co-condensation (1 h), warming (3 h), and
pumping off of excess SbF5 at room temperature to constant
weight a maximum vacuum is maintained. The reaction product is collected with exclusion of moisture ;yield 8.6 g (I 3 mmol)
R r 0 , F + SbF,
SbFs
(2ai
An inhomogeneous di~tribution'~]
of ( 1 ) in the co-condensate is manifested in a red coloration owing to formation
of the thermally more stable dibromine salt (3):
9 B r 0 2 F + 5 SbF,
-+
(1)
4[Br2]'[SbF,]131
+ [BrF,]'[SbF,]-
+ 902
141
+ 6.72NaF
6.72NaSbF6 + 3 0 2 + BrFi
+ BrZ
Table 1. Fundamental vibrations of the bromyl cation and ofselenium dioxide
[.I.
______
_ _ _ ~ -
IR
[2]
[4]
[5]
161
171
Co-condensation reactions have hitherto become known through syntheses with high-temperature species, especially metal atoms. For a survey,
see Angew. Chem. 8 7 , 213--244. 295-345 (1975); Angew. Chem. Int.
Ed. Engl. 14, 193--222, 273-321 (1975).
M . Schrneisser and E . Puinmer, Angew. Chem. 67. 156 (1955): 69, 781
(1957).
Caution: O n separate deposition of ( I ) and SbFs, ( 1 ) may decompose
explosively during thawing.
K . 0.Christe and W. S u ~ ' o d n g ,Inorg. Chem. 12, 2879 (1973); A . 1.
Kurrlin, Z . K . Nikitina, Y E Kharitonou, and !L Y Rosolocskii, Russ.
J. Inorg. Chem. 1 5 , 480 (1970).
G . Hrrzberg: Molecular Spectra and Molecular Structure 11. Van Nostrand, New York 1945. p. 228, 229.
D. B o d , G. Briggs, H . Huber, G. A. Ozin, E. A . Robinson, and A. Vandrr
b e t , Chem. Commuii. 1971, 686; S.Niiniiuntr Cesaro, M . Spoliti, A.
J . H i i i c / d i f r , and J . S. Odqen, J. Chem. Phys. 55, 5834 ( I 971 ).
K . 0. Christe, C . J . Schack, D. Philipooich, and cti Sarvodny, Inorg.
Chem. 8,2489 (1969).
Xenon Oxide Difluoride, XeOF2[**I
The salt-like character of ( 2 a ) is apparent from its IR
and Raman spectra. In addition to the characteristic frequencies expected for [Sb2F11]- and [Sb3F16]-r41, the only other
bands found showed the frequency shifts calculated for a
bent [Br02]+ species having C2"symmetry on isotope substitution'']. The fundamental vibrations of the cation reveal
the similarities expected for isoelectronic species with those
of monomeric selenium dioxide (cf. Table 1).
vi(A1)
Raman
[I]
[3]
[BrOz]+ is already formed at temperatures below -80°C
in a solid state reaction. Compound ( 2 a ) is difficult to obtain
colorless (usually yellowish because of traces of dark red ( 3 ) ) .
It is stable at room temperature (dissociation pressure < 10-3
torr). Atmospheric moisture o r warming to 80°C effects rapid
decomposition.Thermal degradation leads by way of evolution
of oxygen to ( 3 ) and ( 4 ) as primary products. Vacuum pyrolysis of (2a) in the presence of an excess of sodium fluoride
permits precise determination of the amount of [Br02]+ in
(20).
3(20)
Received: October 20, 1975 [Z 354a IE]
German version: Angew. Chem. 88,189 (1976)
Publication delayed at author's request
CAS Registry numbers:
i l l , 22585-64-4; (2a), 58409-46-4; (Zh), 58409-47-5;
SbF,, 7783-70-2; [Br1*02]+, 58384-59-1
[Br0,]+[SbF6(SbF5
(1)
CBr02l+CSbF6(SbF,),.241-.
By Eberhard Jacob and Robert Opferkuch[*]
Dedicated to Professor Josef Goubeau on the occasion of his
75th birthday
We have been able to synthesize and isolate a xenon oxide
difluoride which has formerly only been detected by spectroscopy['] ; the method employed was low-temperature co-condensation. A solid co-condensate of xenon tetrafluoride and
water (molar ratio 1 : 1.1) transforms into xenon oxide difluoride between -80 and -50°C.
XeF4
+ H,O
XeOF,
-+
vdB1)
\'z(Ai )
IR
Raman
IR
Raman
354s
375 s
373 s
355 m
375 m
382 m
897 s
930s
965 s
889m
932m
967 m
+2
HF
In order to avoid the reactionL3'
[Br'*O2]+
[BrO,]'
Se02 161
832vw
876vw
922 w
825 s
865 s
933 s
XeF4
+ 2H20
-+
Xe
+ O2 + 4 H F
~
[a] Monomeric SeO, in an argon matrix.
Bromyl hexafluoroarsenate, [Br02] [AsF,] - (2 b ) , arises
on co-condensation of ( I ) and arsenic pentafluoride at
- 196 "C and warming to - 50°C. In a high vacuum ( 2 h ) volatilizes above - 35 "C with decomposition. The IR spectrum
of a thin film of this salt shows the fundamental vibrations
of the cation and the anion'71.
+
p] Dr. E. Jacob
Institut fur Kernverfahreustechnik des Kernforschungszentrums
Postfach 3640, 7500 Karlsruhe I (Germany)
Abteilung fur Anorganische Chemie der Universitat
Oberer Eselsberg 0 26, 7900 Ulm (Germany)
[**I Low-temperature co-condensation of fluorine compounds, Part 1
158
the hydrogen fluoride liberated on hydrolysis is continuously
pumped off.
XeOF2 is a pale yellow nonvolatile solid which is stable
up to -25°C. It decomposes on slow warming (=2O0C/h)
to - 15"C with decoloration according to r41:
2XeOF2
+
Xe02F2
+ XeF2
[*] Dr. E. Jacob and DipLChem. R. Opferkuch
Institut fur Kernverfahrenstechnik des Kernforschungszentrums
Postfach 3640, 7500 Karlsruhe 1 (Germany)
Abteilung fur Anorganische Chemie der Universitat
Oberer Eselsberg 0 26, 7900 Ulm (Germany)
p*] Low-temperature co-condensation of fluorine compounds, Part 2.- -Part
I : ref. [I].
Aiigew. Chenz. l n t .
Ed. Engl. I Vol. 15 ( 1 9 7 6 ) N o . 3
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