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Dibromine Pentoxide Br2O5.

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[lo] M. Neuenschwander. P Bonzli. Heli.. Chmi. Arrrr 1991, 74. 1823.
[ I l l 2. Yoshida. Y. Taiuara. J. Am. Cher?~.
S o < . 1971. 93, 2573.
to note that the similar reaction o f 3 with the less nucleophilic
hnoiiatetraenide failed to give 2 [9].
[I31 UV(C-HCI,. 25 C ) . i,,, ( B ) = 407 (8650), 290 (12900). 255 (8590) nm: IR
(KBr. 25 C ) - v = 2970m-s. 2930111. 2 8 7 0 ~ .1915m. 1538s. 1485w. 1 4 3 5 ~ - m .
1415m-s. 1380m-s. 1360m-s. 1345m-a, 1300m-s. 1 2 1 5 ~ - m .1190m. 1 0 7 5 ~ .
8 7 0 ~ 685w.
.
615m c m - ' : ' H NMR (600MHz. CDCI,, 25 C}:d =7.29 (in,
2H).7.17(in.2H).7.12(m.2H),7.00(m,2H),
.168(q,8H): 1.39(t, 12Hj[14,
151; " C NMR ( 1 0 0 M H r . CDCI,. 0 ) ; 6 =128.9s. 128.7s. 113.5d. 113.2d,
112.4d. 107.4d. 97 8s. 47.41. 14.7q; MS: high-resolution MS of M t: 296.2257
(calcd. C.H.N. 296.2253)
[I41 ' H NMR o f 3 (300 MHz. CDCI,. 25 C. 6 values): N-CH,: 3.52 (q. 4 H ) . 3.49
(q. 4 H ) : N-CH,-CIf,: 1.33 ( t , 6 H ) . 1.29 (t. 6 H ) . Similar to 3 the N-CH? and
N-CH,-('H, groups 01'2 give t w o multiplets d u e to the hindered rotation:
7, =
25 C for the N-CH, groups, AG' ~ 1 1 . kcdlmol-'.
5
Thisis the only
temper'iture-dependent process observed in the ' H N M R spectrum of 2 he[\reen XI) a n d + 5 0 C
[ I S ] Result, of thc ' H N M R analysis of 2 (600 MH7. CDCI,, 25 C. 6 values):
H-1.8 7 29: H-2.7: 7.00; H-3.6: 7.17: H-4.5: 7.12. ' J couplings:
. I , i = J - , = 1 3 . 5 X : J 2 , = J , 7 = 1 1 . 7 8 ; J,,,=J5,,=13.16: J , , = 1 1 . 7 0 H z ;
' J coupling^: J , . , = J , . , = 0 . 1 2 . J , , , = 0 . 2 1 : . J 2 , 4 = J 5 1 = 0 . 1 5 . J 3 \ =
.I, ,, = 0.1 5 Hz.
[16] Note that all tbe NMR parameters of nonpolar nonafulvenes including l a
( R ' = K' = H ) are similai- to those 1 b in CDCI, at room temperature. The
onl) diffcrence is that they are not influenced by solvents or temperature.
[17] C-9of 1 b is the only ring-C atom showing an opposite trend5. This is probably
main11 due to the conformational changes involved with 1 b + 1.'b which are
expected to h,i\e a pronounced effect on C-9 (in 1b' the formamidinium unit
I S supposed to be out of the plane of the ring). Furthermore, the exocychc
"enediamine \\istern" is expected to induce a considerable negative charge at
C-9. ewii in the case of the olefinic stucture 1 b.
[18] Similarly~the UV spectrum o f 2 (CDCI,. 25 C) i b nearly identical with that of
I b (CH,CI,. - 80 C [3]).
[I91 CCI,. CDCI,. [DJbenzene. [DJTHF. CD,CI,. [DJacetone. CD,CN
[20] Several attempts at a n X-ray analysis of 2 have failed \o far because the
coinpound only crystallizes as polycrystals.
~
~
Dibromine Pentoxide BrZOS**
Dieter Leopold and Konrad Seppelt"
Recently we synthesized pure Br,O,, which according to its
crystal structure analysis can be described as Br-0-BrO, .['I
Together with the results of the structure analysis of Br,O by
using EXAFS (Extended X-ray Absorption Fine Structure) .['I
these are the first secure structural data of bromine oxides. After
the unequivocal proof of the existence of Br,O and Br,O,, the
question arose whether a bromine perbromate (BrOBrO,) identified with the EXAFS method[31was perhaps in fact Br,O, . [ I 1
The basic difficulty of the work with bromine oxides is their
thermal instability. This is the reason why in earlier literature
additional bromine oxides were postulated, although only elemental analysis and sometimes Raman spectroscopy were used
for their characterization, and a review also gave the impression
that the syntheses are not always r e p r ~ d u c i b l e . [ ~ '
In the synthesis of Br,O, from bromine and ozone in CFCI,
at -78 C. we have observed a second bromine oxide. This is
colorless, and thus should no longer contain an 0 - B r ' group,
and forms on longer ozonization time, therefore a higher oxygen
content was to be assumed. In contrast to Br,O,, it is insoluble
in CH,CI,. In order to synthesize this compound in a pure form.
we ozonized elemental bromine in CH,CI, at -78°C. In this
way the color of the solution lightens from brown (Br,) via
[*] Prof. Dr. K . Seppelt, D. Leopold
lnstitut lur Anorganische und Analytische Chemie der Freien Universitit
Fabeckstrassc 34-36. D-14195 Berlin (FRGI
~,
Telefar. Int. code + (30)838-2424
[*'I Thib \ t o i - k ~ i i supported
s
by the Fonds der Chemischen lndustrie
orange (Br,O,) to colorless; from the orange-colored step onwards, an initially yellow, then almost colorless powder precipitates [Eq. (a)]. This powder decomposes on warming above
Er,-
4
CH&I,.
-78 QC
Er - 0 - BrO,
4
0,Br - 0 - BrO,
CYCI,.
-78 Oc
-40 "C, occasionally with detonation. Propionitrile was found
to be a suitable solvent from which this compound crystallizes
out in the form of large colorless needles; an increase in weight
with respect to the amount of powder used indicates the incorporation of solvent in the crystal. These needles melt at about
-20 'C with decomposition.
The crystal structure analysis characterized the new oxide as
Br,O,, which crystallizes with three molecules of propionitrile
(Fig. 1). Since the four Br . ' . N contact distances between pro-
Brl
Br2
Fig, 1. structure
of the ~ ~molecule
~ 0
ill the%
cocrqsralllzate
B ~ ~ o , . ~,CN
~ , H
(ORTEP plot. thermal ellipsoids at 50% probability level). Distances [pin] m d
angles ['I: B r l - 0 1 1 160.6(12), B r l - 0 1 2 161.1(2), B r l - 0 189.6(2). Br2 0 2 1
187,5: ol,-Brl.012 lo9,9(l), O - B r l - O l l
161,3(2), Br2-022 160,6(2). B r 2
94.2(1). 0 - B r - 0 12 102.6(1). 0 21-Br2-0 22 109.0(1), 0 - B r 2 - 0 21 103.3. 0-Br20 2 2 94.9(1), B r l - 0 - B r 2 121.2(1)
pionitrile and Br,O, are quite large (278.7(2)-290.1(1) pm). we
consider Br,O, in this cocrystallisate as a largely undisturbed
molecule. As in Br,O, it is not difficult to differentiate between
terminal B r - 0 double bonds (160.6-161.3(2) pm) and the
B r - 0 single bonds to the bridging oxygen atom (187.5(2),
189.6(2) pm) in Br,O,. The bromine atoms are pyramidally surrounded by the oxygen atoms, as to be expected for BrVcenters;
the angle at the bridging oxygen atom is with 121.2(1)' likewise
in the expected range. The terminal oxygen atoms at the two
bromine atoms are eclipsed, the deviations from this are maximally 0.1 pm. This distinguishes Br20, from 120s.
The structure of the latter has been studied both as a pure substancel']
and also as a cocrystallisate HIO3~1,O5("HI,0,"),L61 and its
terminal oxygen atoms are staggered. However, the structure of
120, is dominated by intermolecular 0 .. . I interactions (up to
223 pm). The Raman spectrum of solvate-free Br,O, is in agreement with the structure shown in Figure 1. The valence frequencies of the double bonds, those of the single bonds, and the
deformation vibrations are significantly separated from each
another. The Raman spectrum, however, differs from that described in 1976 for a Br,O,.[']
The unambiguous existence of Br,O,. which is mixed with
Br,O, if purification is not carried out, questions once again the
existence of Br,O,, which according to the Raman spectra
should occur in two forms, O,Br-BrO,['] and OBr--OBrO,,~'hl
but according to the EXAFS spectrum should have the structure
BrOBr0,.[31
The stiuctures of Br,O, Br,O,, and Br,O, indicate the building principles for bromine oxides: bromine in the oxidation
state + 1 occurs in a terminal position with a weak interaction to
another bromine atom, and a bromine atom in the oxidation
state 5 is pyramidally surrounded with two short and one long
+
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bond to the coordination partners. The combination of these
two building blocks leads to the least unstable compounds of the
system Brio. The relationship to chlorine is apparent in the
oxidation state 1 (e.g. CI2O), that to iodine in the oxidation
state + 5 (e.g. 1 2 0 s ) .
+
E.uperitnenral Procedure
After drying over silica gel. ozone prepared in the ozone generator was introduced
into a solution of Br2 (l00mg) in CH,CI, ( 5 mL) at -78 'C. The color of the
solution lightened. and this was accompanied by the precipitation of initially an
orange-colored. and later an almost colorless solid. When the solution had lost its
color, i t was decanted and dried under vacuum at -50'C. Crystallization in the
temperature range from -50 C to -90 C from C,H,CN gave Br20;3C,H,CN
in the form of large colorless needles: the solution had a tendency towards supersaturation. Raman (solid. krypton ion laser. 647.0 nm): i(Br=O): 868(40). 835(15).
803(90). 774(20): i.(Br-0): 539(30). 511(35); 6: 376(20). 351(1no), t61(30).
110(30)cm-'. Crystal structure analyais: u =1239.6(2). h = 881.7(1). c =
1451.8(2)pm, /f=103.82(1), V=1609x10bpm3. -145'C. P2,:,,.
2=4. p =
49.3 c m - ' 69XX measured reflections in the range 0 = 2-35 , + 17. - A . +I. 6434
independent rcllections. R,,,, = 0.026. 3617 reflections with F > 3 u ( F ) , R = 0.042.
R, = 0.029.218 parameters W = 1.56/u2(F).Further detailsof thecrystal structure
investigation may be obtained from the Fachinformationsrentrom Karlsruhe. D76344 Eggenstein-Leopoldshafen (FRG) on quoting the depository number CSD57939.
Received: November 29. 1993 [Z6519IE]
German version: AnKiw. Clzm. 1994, 1/16. 1043
[I] a) R. Kuschel. K. Seppelt. Aiiguiv. Chum 1993. 105, 1734-1735; Anguii. C h ~ 7 .
Inr. Ed h g l . 1993. 32, 3632-1633 b) Because of the similarity of the Raman
spectra, a Bi-,0, identified by L L . Pascal et al. in 1974 is probably identical with
the Br,O, investigated by crystal structure analysis. J.-L. Pascal, A. C. Pavia, J
Potier. A. Potier. C. R. Acud. Sci. Siv. C 1974. 43-45: ;bid 1975. 661-664.
[2] W. Levason. J. S. Ogden, M. D. Spicer. N. A . Young. J. Am. Chrm. Soc. 1990.
112. 1019 1022
[3] T. R. Gilson. W. Levason. J. S. Ogden, M. D. Spicer. N. A. Young, J. Am. C/iiwi.
see. 1992. 114. 5469-5470.
[4] M. Schmeisser. K. Brindle. A h . I n u r ~ Choii.
.
Rudiocl~em.1963, 5. 41 -89.
[5] K. Selte. A. Kjekshus, AclN Chem. Scrind. 1970. 24, 1912-1924.
[6] Y. D. Feikema. A . Vos. Actu Crj.srollogr. 1966. 20, 169-777.
[7] J.-L. Pascal. A . C. Pavia. J. Poitier. A. Poitier, C. R. Acud. SCI.Scr. C 1976,
53-56.
[XI J.-L. Pascal. J. Poitier. J. Chem. Soc. Chrm. Commrm. 1973. 446- 447.
pounds, in particular Sb(CH,), , are prepared readily. The structure of Sb(CH,), was only recently determined to be unequivocally trigonal bipyramidal by an electron diffraction" 1' and a
single-crystal structure analysis.[13]As(CH,), is equally surprisingly stable, and its vibrational spectra can only be explained in
terms of a trigonal bipyramidal
Since the phenylbismuth(v) compounds are considerably more unstable than the
corresponding antimony(v) compounds, the lacking knowledge
on alkylbismuth(v) compounds can be explained by the expected instability. As we shall show in the following, this prediction
is only partly true.
Trimethylbismuth can be methylated very easily with CH,OSO,CF, [Eq. (a)]. The resulting tetramethylbismutonium triBi(CH,)d S03CF3WH,),
-so,
fluoromethylsulfonate is a colorless compound, which is stable
up to over 150 " C . It is surprising that this simple reaction was
not reported earlier. According to a crystal structure analyS ~ S , [the
~ ~Bi(CH,):
I
ion is tetrahedral (Fig. 1 a). Weak interactions to the anion and solvate molecule do not distort the structure significantly. The mean Bi-C bond length of 222 pm is
~
Methylbismuth(v) Compounds**
Stephan Wallenhauer and Konrad Seppelt *
Tetraphenylbismutonium salts,['l pentaphenylbismuth,"] and
hexaphenylbismutate[2.31 are compounds which have been
known for a long time, for which the relation between light
absorption and structure could only be explained recently.r4- *I
In contrast. almost nothing is known about alkylbismuth(v)
compounds.[91To our knowledge, there is only one conference
report about the preparation of Bi(C2H,),CH: I9I as well as the
detection of Bi(CH,): by /ldecay of 210Pb(CH3)4.[101
The
preparation of the bromides ( E / Z )(CH,CH=CH),BiBr, with
melting points of 65 and 142 'C, respectively, could not as of yet
be reproduced, and this preparation is also questionable in light
of the following observations.[' This lack of knowledge is actually surprising, since the corresponding alkylantimony(v) com[*I
[**I
Prof. Dr. K . Seppelt. DipLChcni. S. Wallenhauer
Institut fur Anorganische und Analytische Chemie der Freien Universitit
Fabeckstrasse 34-36. D-14195 Berlin (FRG)
Telefax: Int. code + (30)838-2424
This work %'assupported by the Deutsche Forschungsgemeinschaft, the Fonds
der Chemisehen Industrie, and the Graduiertenkolleg "Synthese und Struktur;iuRlZrung niedermolekuixrer Verbindungen".
976
,\C/ VCH ~ ~ r l u ~ , ~ g e s r N snc h~ H
~ u, 0-69451
~rfr
Wi+~heim, 1994
Fig. 1. Structures ofthe cation of Bi(CH,):SO,CF;.CH,CN
(a). of Bi(CH,),CI,
(b), of Bi(CH,), (c), and of the anion of [Li(thf),]'[Bi(CH,)J
(d) in the crystal
(ORTEP plots: thermal ellipsoids at the 50% probability level). a) Bond lengths
[pm] and angles ['I of Bi(CH,)::
Bi-C 222.0(10). 223.0(10), 221.0(7): C-Bi-C
112.0(4), 109.6(3), 108.9(2). b) The asymmetrlc unit of Bi(CH,),CI, contains one
acetone molecule. Bond lengths [pm] and angles [=I: Bi-CI 260.2(2), 261.7(2), Bi-C
218.9(7). 219.6(6). 220.7(6); CI1-Bi-CI2177.8(1), C-Bi-C 117.4(2), 127.3(2).
115.3(2). The large C-Bi-C bond angle is explained by a long B i . . . O contact of
323 pm to the oxygen atom of the acetone molecule. c) As i n the structure of
Sb(CH,), [13]. the Bi(CH,), molecule here is also doubly disordered in the lattice.
The second orientation is formed by a 90 rotation about the Bi-C 1 axis. Only one
orientation IS shown for better clarity. Bond lengths [pm] and angles [ I : Bi-Cl
230(2). Bi-C2 227(1), Bi-C3 228(2); Cl-Bi-C2d 119.3(5), CI-Bi-C3a 89.9(5).
C 2a-Bi-C 2b 12 1.4(5). C 2a-Bi-C 3a 90.4(6). C 2a-Bi-C 3b 89.9(5). C 3a-Bi-C 3b
179.8(8). d) Bond lengths [pm] and angles ['I of Bi(CH,);: Bi-C 216(1), 233(1).
230(2); C-Bi-C 89.6(4), 90.0. 90.0, 180.0.
0570-0X33/94/0909-U976 B 10.00f ,2510
Airgri3. Cliem. I n l . Ed. Engl.
1994, 33. No. 9
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