Stable Chloro- and Bromoxenate Cage Anions; [X3(XeO3)3]3- and [X4(XeO3)4]4- (X = Cl or Br)

Article abstract of DOI:10.1021/jacs.7b04067

The number of isolable compounds which contain different noble-gas-element bonds is limited for xenon and even more so for krypton. Examples of Xe-Cl bonds are rare, and prior to this work, no Xe-Br bonded compound had been isolated in macroscopic quantities. The syntheses, isolation, and characterization of the first compounds to contain Xe-Br bonds and their chlorine analogues are described in the present work. The reactions of XeO₃ with [N(CH₃)₄]Br and [N(C₂H₅)₄]Br have provided two bromoxenate salts, [N(C₂H₅)₄]₃[Br₃(XeO₃)₃] and [N(CH₃)₄]₄[Br₄(XeO₃)₄], in which the cage anions have Xe-Br bond lengths that range from 3.0838(3) to 3.3181(8) ?. The isostructural chloroxenate anions (Xe-Cl bond lengths, 2.9316(2) to 3.101(4) ?) were synthesized by analogy with their bromine analogues. The bromo- and chloroxenate salts are stable in the atmosphere at room temperature and were characterized in the solid state by Raman spectroscopy and low-temperature single-crystal X-ray diffraction, and in the gas phase by quantum-chemical calculations. They are the only known examples of cage anions that contain a noble-gas element. The Xe-Br and Xe-Cl bonds are very weakly covalent and can be viewed as σ-hole interactions, similar to those encountered in halogen bonding. However, the halogen atoms in these cases are valence electron lone pair donors, and the σ?_Xe-O orbitals are lone pair acceptors.

Full text of DOI:10.1021/jacs.7b04067

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Article
Stable Chloro- and Bromoxenate Cage
3
3
3
3-
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3
4
4-
Anions; [X(XeO)] and [X(XeO)] (X = Cl or Br)
James T. Goettel, Veit Haensch, and Gary J. Schrobilgen
J. Am. Chem. Soc., Just Accepted Manuscript • Publication Date (Web): 25 May 2017
Downloaded from http://pubs.acs.org on May 25, 2017
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Stable Chloroꢀ and Bromoxenate Cage Anions;
3−
4−
[
X (XeO ) ] and [X (XeO ) ] (X = Cl or Br)
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3 3
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James T. Goettel, Veit G. Haensch, and Gary J. Schrobilgen*
Department of Chemistry, McMaster University, Hamilton, ON L8S 4M1, Canada
ABSTRACT: The number of isolable compounds which contain different nobleꢀgas−element
bonds is limited for xenon and even more so for krypton. Examples of Xe−Cl bonds are rare and
prior to this work, no Xe−Br bonded compound had been isolated in macroscopic quantities. The
syntheses, isolation, and characterization of the first compounds to contain Xe−Br bonds and
their chlorine analogues are described in the present work. The reactions of XeO with
3
[
N(CH ) ]Br and [N(C H ) ]Br have provided two bromoxenate salts, [N(C H ) ][Br (XeO ) ]
3 4 2 5 4 2 5 4 3 3 3
and [N(CH ) ][Br (XeO ) ], in which the cage anions have Xe–Br bond lengths that range from
3
4
4
3 4
3.0838(3) to 3.3181(8) Å. The isostructural chloroxenate anions (Xe–Cl bond lengths, 2.9316(2)
to 3.101(4) Å) were synthesized by analogy with their bromine analogues. The bromoꢀ and
chloroxenate salts are stable in the atmosphere at room temperature and were characterized in the
solid state by Raman spectroscopy, lowꢀtemperature singleꢀcrystal Xꢀray diffraction, and in the
gas phase by quantumꢀchemical calculations. They are the only known examples of cage anions
that contain a nobleꢀgas element as part of the cage structure. The Xe−Br and Xe−Cl bonds are
weakly covalent and can be viewed as σꢀhole interactions, similar to halogen bonds. However, in
these cases, the halogen atoms are valence electron lone pair donors and the σ*Xe–O orbitals are
acceptors.
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INTRODUCTION
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Since the discovery of nobleꢀgas reactivity over 50 years ago, xenon has been shown to form a
diverse range of compounds that are isolable in macroscopic amounts, but the number of nobleꢀ
gas–element bonds was initially limited to those formed with the highly electronegative fluorine
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and oxygen atoms. The majority of xenon compounds were and still are fluorineꢀ and oxygenꢀ
bonded to xenon. The diversity of xenon chemistry has been significantly broadened and
enriched by the syntheses and structural characterization of macroscopic quantities of
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3
compounds containing xenon bonded to nitrogen, and carbon; and to several compounds
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5
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7,8
containing Xe–Au, Xe–Xe, Xe–Hg, and Xe–Cl bonds. Quantumꢀchemical (QC) calculations
have provided a plethora of geometryꢀoptimized gasꢀphase structures which suggest that many
9ꢀ13
more xenonꢀelement bonds may be synthesized.
Although most xenonꢀelement bonds that
have been predicted by QC calculations are still unknown, a significant number have been
experimentally documented in the gas phase or in lowꢀtemperature nobleꢀgas matrices. Among
those that have been characterized in the gas phase or in lowꢀtemperature matrices, but not in
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macroscopic amounts, are Xe–H, Xe–S, Xe–Si, and Xe–U.
Examples of isolable Xe−Cl bonded compounds are rare and have been limited to
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C F XeCl, [(C F Xe) Cl][AsF ], [XeCl][Sb F ], and the chloroxenates M [(XeO )Cl ] Cl [M
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2 4
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= Cs, Rb]. The crystal structures of M [(XeO )Cl ] consist of extended ClꢀꢀꢀXeO bridged
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3
2
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networks that are severely disordered. The structurally related fluoroxenate salts have also been
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synthesized and partially characterized,
and a lowꢀprecision crystal structure of KFXeO3
has been obtained. The Xe−Cl bond of [XeCl][Sb F ] has significant covalent character and is
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kinetically stable below −10 °C. In contrast, QC calculations indicate that [XeBr] is
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thermodynamically unstable in the gas phase and is likely to be difficult to isolate.
Previous studies have failed to provide isolable Xe–Br bonded compounds, but several
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129m
transient species have been identified. Evidence for the shortꢀlived
XeBr isotopologue,
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129
−
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which results from βꢀdecay of
I in [ IBr ] , has been obtained from
Xe Mössbauer
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29m
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spectroscopy. The
XeBr isotopologue decays by γꢀemission to XeBr and was observed as
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a quadrupoleꢀsplit resonance in its Xe Mössbauer spectrum. Attempts to synthesize XeBr in
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nobleꢀgas matrices were unsuccessful. Quantumꢀchemical calculations indicate that XeBr is
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unstable towards redox decomposition to the elements and has a dissociation energy, 0.1 eV,
(
NgX ꢀ Ng + 2X˙ (Ng = Kr or Xe and X = F or Br, respectively) which is substantially less
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3
than that of KrF (1.67 eV). Ultraviolet irradiation and subsequent annealing of HBr in Xe
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matrices has afforded HXeBr which was characterized by infrared spectroscopy. Although a
−
1
band assigned to the XeBr stretch was not observed, bands at 489 and 486 cm were assigned to
the HXeBr bending modes. It was subsequently shown that HXeBr is stable in CO matrices up
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to ca. −173 °C, whereas HXeBr in xenon matrices rapidly decomposes above −213 °C.
Excimer lasers that employ Xe and Br as the gain medium produce an emission at 281.9 nm that
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is due to dissociation of the XeBr* exciplex into Xe and Br. The synthesis of (2,6ꢀ
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F C H )XeBr has been reported along with its characterization by Xe, F, and C NMR
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spectroscopy (−80 °C), however the compound was not isolated and the existence of a Xe−Br
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bond remains unsubstantiated. The reaction of CsBr and XeO in water (pH = 9.5, 0 °C) was
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2
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reported to yield a precipitate that was presumed to be CsBrXeO , however the reaction proved
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to be difficult to reproduce, yielding a precipitate only twice out of ten attempts. The precipitates
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were characterized at room temperature by infrared spectroscopy and showed intense bands
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attributable to Xe–O stretching modes but provided no definitive evidence for a bromoxenate
anion.
Spectroscopic methods have thus far failed to provide conclusive evidence for an isolable
Xe–Br bonded compound. The elusiveness of Xe–Br bonds is largely a consequence of the
strong oxidant properties of xenon in its common oxidation states +2, +4, +6, and +8 which may
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oxidize the bromine ligand. Although XeO is a very strong oxidant with marginal kinetic
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stability at room temperature (t1ꢁ2 = 4.4 years), it is compatible with a number of organic
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solvents such as tꢀbutanol, propionitrile, and acetonitrile and forms adducts with nitrogen
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bases. Despite prior efforts to synthesize CsBrXeO , XeO remains a possible candidate for
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3
Xe−Br bond formation. Xenon trioxide is one of very few nobleꢀgas compounds that is stable in
3
2
aqueous solutions and in air, however, in the solid state all three known phases of XeO3 are
highly endothermic and shockꢀsensitive and can detonate at the slightest provocation. Due to its
shockꢀsensitivity, very little research relating to the chemistry of XeO has been forthcoming.
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The present study describes the syntheses, isolation, and characterization of the first Xe–
Br bonded compounds, [N(C H ) ] [Br (XeO ) ] and [N(CH ) ] [Br (XeO ) ], and their chlorine
2
5 4 3
3
3 3
3 4 4
4
3 4
analogues ([N(C H ) ] [Cl (XeO ) ] and [N(CH ) ] [Cl (XeO ) ]) which also provide rare
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5 4 3
3
3 3
3 4 4
4
3 4
examples of Xe–Cl bonded compounds. The salts have been structurally characterized in the
solid state by lowꢀtemperature, singleꢀcrystal Xꢀray diffraction and Raman spectroscopy.
Vibrational assignments have been made with the aid of quantumꢀchemical calculations. The
natures of the Xe–Br and Xe–Cl bonds have been examined using natural bond orbital (NBO)
analyses.
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RESULTS AND DISCUSSION
Synthesis. Tetraalkylammonium chloride and bromide (alkyl = CH and C H ) were selected
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as halide ion sources for the syntheses of haloxenate salts because their cations are oxidatively
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resistant and the salts have appreciable solubilities in CH CN. Initial attempts to form
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bromoxenate salts used aqueous KBr which only led to mixtures of oxidized products such as
KBrO . However, the reactions of [N(CH ) ]X and [N(C H ) ]X (X = Cl or Br) with XeO
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3 4
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5 4
resulted in the formation of four new haloxenate anions. The reactions of XeO with
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[
[
N(C H ) ]Br and [N(CH ) ]Br yielded light yellow, blockꢀshaped crystals of
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N(C H ) ] [Br (XeO ) ]ꢂ2CH CN (1ꢂ2CH CN), plateꢀshaped crystals of [N(CH ) ] [Br (XeO ) ]
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5 4 3
3
3 3
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3
3 4 4
4
3 4
(2), and thin needleꢀshaped crystals of 2ꢂxCH CN. Analogous reactions with [N(C H ) ]Cl and
3
2
5 4
[
N(CH ) ]Cl yielded blockꢀshaped crystals of [N(C H ) ] [Cl (XeO ) ] (3) and needleꢀshaped
3 4 2 5 4 3 3 3 3
crystals of [N(CH ) ] [Cl (XeO ) ] (4). With the exception of 1ꢂ2CH CN, which was light
3
4 4
4
3 4
3
yellow in color (see Raman Spectroscopy), all other salts were colorless. The chloroxenate cage
anions are isostructural with their bromoxenate analogues (vide infra). Attempts to synthesize
iodoxenate anions by reaction of KI and [N(C H ) ]I with XeO at −45 and −78 °C in CH CN
2
5 4
3
3
and CH CH CN solvents, respectively, were unsuccessful. The Raman spectra of the reaction
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2
−
− 34
products showed that I had been oxidized to IO .
3
Xꢀray Crystallography. The lowꢀtemperature singleꢀcrystal Xꢀray structures of 1ꢂ2CH CN, 2,
3
3
, and 4 were determined. A summary of crystal data and refinement results is given in Table 1
and a summary of important bond lengths and angles is given in Table 2. A more complete list of
geometrical parameters is provided in Table S1.
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Table
1.
5 4 3
Summary
of
3
Crystal
Data
3
and
Refinement
Results
3 4
for
(2),
[
[
N(C H ) ] [Br (XeO ) ]ꢂ2CH CN
(1ꢂ2CH CN),
3 4 4
[N(CH ) ] [Br (XeO ) ]
2
3
3 3
3 4 4
4
N(C H ) ] [Cl (XeO ) ] (3), and [N(CH ) ] [Cl (XeO ) ] (4)
2
5 4 3
3
3 3
4
3 4
Compound
1·2CH CN
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4
3
0
1
2
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0
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0
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chemical formula
space group
a (Å)
b (Å)
c (Å)
C
28
H
66Br
3
N
5
O
9
Xe
3
C
16
H
48Br
4
N
4
O
12Xe
4
C
24
H
60Cl
3
N
3
O
9
Xe
3
C
H48Cl N O12Xe
16 4 4 4
Cc
15.7384(4)
15.1019(4)
38.5898(12)
90
101.220(2)
90
P2 /n
9.3724(6)
11.6016(7)
18.1066(11)
90
100.1090(10)
90
Pna21
P
1
1
19.0517(7)
13.3595(4)
15.4892(6)
90
90
90
9.6098(2)
10.1137(2)
10.4220(2)
79.1150(10)
72.5070(10)
76.0370(10)
930.10(3)
α (deg)
β
(deg)
γ (deg)
3
V (Å )
8996.7(4)
1938.3(2)
3942.3(2)
Z (molecules/
unit cell)
mol. wt. (g mol )
calcd density (g cm ) 1.846
8
2
4
1
–
1
1250.48
1333.42
2.285
−160
1035.00
2.812
−173
1155.58
2.063
−173
–
3
T (°C)
−173
4.959
−1
ꢀ
R1
(mm )
7.640
2.812
3.952
a
0.0459
0.1141
0.0254
0.0552
0.0454
0.0885
0.0155
0.0375
b
wR2
a
b
2
o
2 2
c
2 2
o
½
R = Σ||F |–|F ||/Σ|F |. wR = [Σ(w(F –F ) )/Σ(w(F ) )] .
1
o
c
o
2
The Xꢀray crystal structure of [N(C H ) ] [Br (XeO ) ]ꢂ2CH CN contains two
2
5 4 3
3
3 3
3
crystallographically unique asymmetric structural units that consist of wellꢀseparated
3
−
+
[Br (XeO ) ] anions, [N(C H ) ] cations, and CH CN molecules (Figures 1a and S1). The
3
3 3
2
5 4
3
3
−
[
Br (XeO ) ] anion has a pseudoꢀmirror plane that contains three Xe atoms and a unique ꢃBr
3 3 3
atom that is coordinated to two Xe atoms. Significant differences occur among the Xe–ꢃBr bond
lengths (3.1375(7)/3.1047(7) and 3.3181(8)/3.2649(8) Å) of both unique anions. These
differences may be attributed to the weak covalent characters of these bonds and their
susceptibility to perturbation in their respective crystal environments. The shorter Xe–ꢃBr bonds
occur trans to primary Xe–O bonds whose O atoms are bridged to neighboring XeO moieties.
3
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3
−
Figure 1. The Xꢀray crystal structures of (a) one of two crystallographically unique [Br (XeO ) ] anions
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3 3
4−
+
+
in 1ꢂ2CH CN and (b) the [Br (XeO ) ] anion in 2. The [N(C H ) ] and [N(CH ) ] cations and CH CN
molecules have been omitted from (a) and (b) for clarity. Thermal ellipsoids are shown at their 50%
probability levels.
3
4
3 4
2
5 4
3 4
3
Donation of electron density from the unique bridging O atom of this structure to a neighboring
XeO moiety leads to a shorter Xe–ꢃBr bond by enhancement of the acceptor strength
3
(electrostatic potential) of the Xe center and, correspondingly, Xe–ꢃBr σꢀhole bond strength. A
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similar trend has been noted for the XeꢀꢀꢀN bonds in XeO alkylnitrile adducts. The two
3
remaining ꢃ Br atoms are each coordinated to three Xe atoms and show less variation among
3
Xe–ꢃ Br bond lengths (3.1698(7)–3.2606(7)/3.2019(7)–3.2738(7) Å). Two Xe atoms are
3
coordinated to the ꢃBr atom and to both ꢃ Br atoms. The remaining Xe atom also coordinates to
3
both ꢃ Br atoms and to an O atom of an adjacent XeO moiety (2.861(5)/2.764(6) Å).
3
3
The coordination spheres of the Xe atoms are distorted octahedra in which the transꢀ
Br−Xe−O, cisꢀBr−Xe−O, and cisꢀBr−Xe−Br bond angles range from 161.32(17) to 166.18(18)°,
85.11(17) to 92.61(16)°, and 75.383(17) to 80.091(18)°, respectively. The nitrogen atoms of the
coꢀcrystallized CH CN molecules do not exhibit significant interactions with the Xe atoms which
3
33
contrasts with the Xe−N bonded O XeCNR and O Xe(NCR) (R = ꢀCH or ꢀCH CH ) adducts.
3
3
2
3
2
3
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This suggests that Xe−Br bond formation is favored over Xe−N bond formation, in accordance
with the Xe−Br Wiberg bond indices (WBIs) which are significantly greater than those of the
3
3
Xe−N bonds in the alkylnitrile adducts of XeO3 (see Computational Results).
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
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2
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8
9
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2
3
4
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7
8
9
0
1
2
3
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9
0
4−
+
The crystal structure of 2 consists of [Br (XeO ) ] anions and [N(CH ) ] cations that
4
3 4
3 4
4−
are well separated from one another (Figures 1b and S2). The [Br (XeO ) ] anion has an
4
3 4
35
4−
36
inversion center and is isostructural with
δ
ꢀTeI4 and the [Bi Br ] anion. The tetrameric
4
16
+
−
−
+
structure of
δꢀTeI consists of four TeI cations bridged to four I ions, (I ) (TeI ) , and
4 3 4 3 4
4
−
correspondingly, the [Bi Br ] anion can be described as four BiBr molecules bridged by four
4
16
3
−
−
4−
3−
Br ions, [(Br ) (BiBr ) ] . As is the case of [Br (XeO ) ] , the bromine atoms of
4
3 4
3
3 3
4
−
[
Br (XeO ) ] are bonded to xenon through ꢀꢀ and ꢀ ꢀBr bridges. The Xe−Br bond lengths (ꢀꢀ
4
3 4
3
Br, 3.0838(3), 3.2132(3); ꢀ ꢀBr, 3.1200(2)–3.1691(2) Å) are slightly shorter than those of 1, and
3
3
7
are significantly shorter than the sum of the Xe and Br van der Waals radii (4.01 Å). The
Br−Xe−Br bond angles (80.616(5)–82.970(7)°) of 2 are, on average, greater than those of
1
ꢂ2CH CN (74.24(2)–81.88(2)°).
3
The Xe−O bridge bonds (1ꢂ2CH CN; 1.788(5), 1.793(5) Å and 2; 1.7988(11) Å) are
3
slightly longer in both anions than the terminal Xe−O bonds (1ꢂ2CH CN, 1.762(5)−1.778(5) Å
3
and 2, 1.7719(14)−1.7753(14) Å) which are similar to those of the three phases of XeO3
3
2
(
1.7558(11)–1.7801(11) Å). The average primary O−Xe−O bond angles (98.7(3)−102.3(4)°
(
1ꢂ2CH CN) and 98.89(6)–101.53(7)° (2)) are smaller than those of solid XeO (100.51(5)–
3
3
3
2
105.09(6)°).
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a
3−
4−
Table 2. Selected Bond Lengths (Å) and Angles (deg) for [X (XeO ) ] and [X (XeO ) ] (X
3
3 3
4
3 4
=
Cl, Br) in 1ꢂ2CH CN, 2, 3, and 4
3
3
−
b
4−
3−
4−
[
Br (XeO ) ] (1)
[Br (XeO ) ] (2)
[Cl (XeO ) ] (3)
[Cl (XeO ) ] (4)
4 3 4
3
3 3
4
3 4
3
3 3
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60
3
3
.1375(7), 3.3181(8)
.1047(7), 3.2649(8)
Xe–ꢀX
3.0838(3), 3.2132(3)
3.1200(2)–3.1691(2)
80.616(5)–82.970(7)
97.670(5)
2.9448(14), 3.0808(13) 2.9316(2), 2.9686(3)
3
.1698(7)–3.2606(7)
Xe–ꢀ X
3.070(4)–3.101(4)
74.46(5)–82.76(10)
86.76(4)
3.0192(2)–3.0967(2)
76.766(6)–84.766(6)
105.380(7)
3
3.2019(7)–3.2738(7)
7
7
5.38(2)–80.20(2)
2.79(2)–81.89(2)
X–Xe–X
8
8
5.07(2)
6.38(2)
Xe–ꢀX–Xe
74.26(2)–93.29(2)
72.56(2)–100.58(2)
Xe–ꢀ X–Xe
77.359(4)–98.535(5)
78.43(11)–97.59(13)
82.253(7)–99.642(7)
1.7714(7)–1.7766(7)
1.7937(7)
3
1
1
.760(6)–1.777(5)
.770(5)–1.779(5)
Xe−Ot
Xe−Ob
XeꢀꢀꢀOb
1.7719(14)–1.7753(14) 1.710(11)–1.836(11)
1
.788(5)
1.7988(11)
1.785(4)
2.993(5)
1.794(5)
2
2
.861(5)
.764(6)
2.7129(12)
2.7721(7)
9
9
9.4(2)–102.4(3)
8.8(2)–101.7(2)
O–Xe–O
98.89(6)–101.53(7)
99.8(5)–102.2(2)
99.75(4)–102.24(4)
a
b
A complete list of geometrical parameters is provided in Table S1. Two sets of values result
from two crystallographically unique [Br (XeO ) ] anions in the crystal lattice of (1).
3−
3
3 3
3−
The structure of the [Cl (XeO ) ] anion (compound 3, Figures 2a and S3) is very
3
3 3
3
−
similar to that of [Br (XeO ) ] in 1·2CH CN. Although the bromoꢀ and chloroanions are
3
3 3
3
essentially isostructural, one of the XeO moieties of 3 exhibits a minor disorder. Although the
3
Xe–ꢀX–Xe (X = Cl, Br) bond angles are very similar, the Xe–ꢀ Br–Xe bond angles
3
3−
(72.564(16)–100.58(2)°) of [Br (XeO ) ]
have a significantly greater range than the
3
3 3
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3−
corresponding angles in [Cl (XeO ) ] (78.43(11)–97.59(13)°). The Xe–Cl bonds (2.9448(14)–
3
3 3
3
.101(4) Å) are shorter than the Xe–Br bonds of 1ꢂ2CH CN and the XeꢀꢀꢀO bridge distance
3
(
2.993(5) Å) is significantly longer than those of the bromine analogue (2.764(6), 2.861(5) Å).
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4−
4−
The [Cl (XeO ) ] anion of 4 (Figures 2b and S4) is isostructural with the [Br (XeO ) ]
4
3 4
4
3 4
anion of 2, but the crystal packing arrangements of the cations and anions of 2 and 4 differ, i.e., 2
crystallizes in the P2 /n space group whereas 4 crystallizes in the P space group. The
1
1
Cl−Xe−Cl bond angles span 76.766(6) to 84.766(6)° which is significantly greater than the range
spanned by the bromine analogue (80.616(5)−82.970(7) °). Furthermore, the Xe–ꢀCl–Xe bond
angle (105.380(7)°) is much larger than the Xe–ꢀBr–Xe bond angle (97.670(5)°) of
4
−
[Br (XeO ) ] .
4
3 4
3
−
4−
Figure 2. The Xꢀray crystal structures of (a) the [Cl (XeO ) ] anion in 3 and (b), the [Cl (XeO ) ]
3
3 3
4
3 4
+
+
anion in 4. The [N(C H ) ] and [N(CH ) ] cations have been omitted for clarity. Thermal ellipsoids are
2
5 4
3 4
shown at their 50% probability levels.
Raman Spectroscopy. The Raman spectrum of 1ꢂ2CH CN was initially obtained at −40 °C
3
under liquid CH CN solvent (Figure S5). After solvent removal under dynamic vacuum at ca.
3
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−
30 °C, the lowꢀtemperature spectrum (−120 °C, Figure S6) showed additional intense bands
−
−1
−
−1
due to [Br ] (166 cm , ν (∑ )) and [Br ] (243 cm , terminal ν (A )). After standing four days
3
s
g+
5
s
1
in the atmosphere at room temperature, the light yellow color of the sample faded and the Raman
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60
−
spectrum of the crystalline compound no longer showed bands attributable to CH CN or [Br ] ,
3
5
−
−1
but still showed a mediumꢀintensity band due to [Br ] at 162 cm (Figure 3). The presence of
3
−
−
[
Br ] and [Br ] indicates that oxidation of Br(−I) to Br(I) had occurred and the subsequent
3 5
−
−
decrease in [Br ] and absence of [Br ] upon standing at room temperature is consistent with Br
2
3
5
−
−
−
38
loss due to dissociation of [Br ] and [Br ] into Br and Br . The presence of small quantities
3
5
2
−
−
of [Br ] and [Br ] is also consistent with the intial light yellow color of the sample which
3
5
+
−
−
decreased up standing at room temperature. The [N(CH ) ] salts of [Br ] and [Br ] are orange
3
4
3
5
3
8
and redꢀorange, respectively.
In contrast, the Raman spectrum of 2ꢂxCH CN (Figure S7)
3
showed the sample was free of polybromide anion contaminants and confirmed the presence of
coꢀcrystallized CH CN. The Raman spectra of 1 (Figure 3), 2 (Figure 4), 3 (Figure S8), and 4
3
(
Figure S9) were recorded for the solids in aluminum sample holders in air at 20 °C which
provided Raman spectra free of FEP sample tube bands and confirmed that the compounds are
roomꢀtemperature stable and insensitive to atmospheric moisture.
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o
Figure 3. Raman spectrum of [N(C H ) ] [Br (XeO ) ] (1) recorded at 20 C in an aluminum
2
5 4 3
3
3 3
−
1
+
−
sample holder using 1064ꢀnm excitation. The band at 166 cm corresponds to ν (∑ ) of [Br ] .
s
g
3
The symbol (†) denotes an instrumental artifact.
o
Figure 4. Raman spectrum of [N(CH ) ] [Br (XeO ) ] (2) recorded at 20 C in an aluminum
3
4 4
4
3 4
sample holder using 1064ꢀnm excitation. The symbol (†) denotes an instrumental artifact.
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Complete lists of vibrational frequencies and assignments are provided for 1ꢂ2CH CN, 1,
3
2
, 2ꢂxCH CN, 3, 4, 5, 6, 7, and 8 in Tables S2ꢀS7. Raman spectral assignments were aided by
3
comparison with calculated vibrational frequencies and intensities of the energyꢀminimized gasꢀ
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3−
3−
phase geometries of the [Br (XeO ) ]
(5) and [Cl (XeO ) ]
(6) anions and the
3
3 3
3
3 3
[N(CH ) ] [Br (XeO ) ] (7), [N(CH ) ] [Cl (XeO ) ] (8) ion pairs (Figures S10ꢀS13).
3
4 4
4
3 4
3 4 4
4
3 4
+
+
Vibrational assignments for the [N(CH ) ] and [N(C H ) ] cations and coꢀcrystallized CH CN
3
4
2
5 4
3
3
8ꢀ40
were made by comparison with their previously published assignments.
The most prominent features in the Raman spectra of the haloxenate salts are the Xe−O
stretching and bending modes whose assignments were derived from the four Ramanꢀactive
bands observed for aqueous XeO (317 (E, δ ), 344 (A , δ
), 780 (A , ν ), and 833 (E, ν )
3
as
1
umbrella
1
s
as
−
1 41
cm ) and were confirmed by QC calculations (Tables S2ꢀS5). The highest frequency Xe–O
stretching bands (791, 815 (1); 788−826 (1ꢂ2CH CN); 784−819 (2); 795−826 (3); and 794, 815
3
−
1
(4) cm ) are derived from the asymmetric stretch (E, ν (XeO )) and are well reproduced by the
as
3
−1
calculated frequencies (779−807 (5); 777−806 (6); 790−875 (7); 791−868 (8) cm . The most
−
1
intense XeO stretching bands (762 (1); 759, 764 (2); 747, 765 (3); and 755, 763 (4) cm ) are
3
derived from the symmetric stretch (A ν (XeO )) and are shifted to significantly lower
1
,
s
3
−
1 41
frequencies than that of aqueous XeO (2.0 M) (780 cm ), but are nearly equal to those of αꢀ
3
−
1 29
−1 33
XeO (764 cm ) and O XeNCCH (762 cm ). The stretching bands at 733 (1) and 722 (2)
3
3
3
−1
cm are assigned to the Xe−O stretching modes of the Oꢀbridged XeO moieties.
3
−1
The XeO bending frequencies of the haloxenate anions range from 310 to 359 cm and
3
−
1 32
are similar to those of αꢀXeO (297–351 cm ). The highest frequency bending modes at 337,
3
–
1
3
55 (1); 332, 353 (2); 336–359 (3); and 331–365 (4) cm are derived from the umbrella mode
(
A , δumb(XeO )) where some umbrella modes are inꢀphase and outꢀofꢀphase coupled to one
1
3
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another. Bands derived from the asymmetric bending mode (δ (XeO )) occur at 310 (1); 313 (2);
as
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–
1
312, 321 (3); and 317 (4) cm . The gasꢀphase calculations for 7 and 8, which include the
+
[
N(CH ) ] cations, predict weak vibrational coupling between the XeO bending modes and the
3
4
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cation deformation modes (Table S4).
The remaining lowꢀfrequency bands are assigned to twisting (ρ (XeO ), rocking
t
3
(
ρ (XeO ), and stretching (ν(Xe–Br)/ν(Xe–Cl)) modes, as well as other deformation modes
r
3
involving Br and Cl. For example, in the Raman spectra of 1 and 3, the bands at 128 and 144
−1
cm are assigned to a XeO twist coupled with several ν(Xe–Br) and ν(Xe–Cl) stretches,
2
−
1
respectively. These frequencies are well reproduced by the calculations (126 cm (5) and 147
−
1
−1
−1
cm (6)). Similar frequencies are predicted for 2 (126 cm (7)) and 4 (176 cm (8)), but were
not observed in the experimental spectra. As expected, the coupled modes involving ν(Xe–Br)
stretches occur at lower frequencies than those involving ν(Xe–Cl) stretches. It is not possible to
definitively assign bands that exclusively correspond to ν(Xe–Br) and ν(Xe–Cl) stretches
because their Raman intensities are predicted to be weak (Tables S2 and S4) and therefore may
−1
be obscured by other deformation modes and by an instrumental artifact (84 cm ) in this region
of the spectrum.
Computational Results. Quantumꢀchemical calculations were carried out at the
B3LYP/Def2ꢀTZVPD (Xe, Br, Cl, O)/6ꢀ31+G (N, C, H) level of theory. The optimized
3
−
geometries of the gasꢀphase [X (XeO ) ] (X = Br (5); Cl(6)) anions (Figures S10 and S11,
3
3 3
respectively) are similar to those of their crystal structures. In general, the calculations slightly
overestimated the Xe−X bond lengths (Table S1). Attempts to optimize the gasꢀphase geometries
4
−
of the [X (XeO ) ] (X = Br or Cl) anions were unsuccessful likely due to the high negative
4
3 4
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charges of the anions. The introduction of four [N(CH ) ] cations arranged around each
3
4
4−
[
X (XeO ) ] anion ([N(CH ) ][Br (XeO ) ] (7), Figure S12 and [N(CH ) ][Cl (XeO ) ] (8),
4 3 4 3 4 4 3 4 3 4 4 3 4
Figure S13) resulted in stable ion pairs in which the optimized anion geometries are in good
agreement with those of the crystal structures.
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Natural bond orbital (NBO) analyses (Table S8) show that the Xe−X bonds are consistent
3
−
with weak covalent bonding. The ꢀꢀBr atom of [Br (XeO ) ] has Xe−Br Wiberg bond indices
3
3 3
(
WBIs) of 0.085 and 0.092, whereas those of the ꢀ ꢀBr bridged atoms (0.043–0.075) are smaller.
3
3
−
In [Cl (XeO ) ] , the two Xe−ꢀCl WBIs (0.080 and 0.127) differ to a greater extent, whereas
3
3 3
those of Xe−ꢀ Cl (0.068–0.080) show less variance. The Xe−X WBIs of 7 (ꢀꢀBr: 0.031−0.193;
3
ꢀ3
ꢀBr: 0.042−0.127) and 8 (ꢀꢀCl: 0.039−0.173; ꢀ ꢀCl: 0.031−0.117) have significantly greater
3
ranges and are greater than the average values of 5 and 6. The averages of the secondary XeꢀꢀꢀO
WBIs (0.021 (6), 0.028 (5), 0.037 (8), 0.045 (7)) are less than the WBIs of the Xe–X bonds. The
small bond indices are consistent with weak Xe–X and XeꢀꢀꢀO covalent bonding. The WBIs
(
0.949–0.983) of the terminal Xe–O bonds of the O=XeꢀꢀꢀO bridges are slightly less than the
terminal Xe–O bond indices (1.000−1.162) of the XeO groups which do not participate in
3
O=XeꢀꢀꢀO bridges and are consistent with polarꢀcovalent Xe–O bonds that are similar to those of
free XeO (1.118).
3
The natural population analysis (NPA) charges of the Br atoms in 5 (−0.845, −0.838)
and 7 (−0.776 to −0.752) and the Cl atoms in 6 (−0.822, −0.812) and 8 (−0.849 to −0.800) are
consistent with partial charge delocalization. The NPA charges of the Br atoms in 7 are
significantly more positive indicating greater charge delocalization. The Xe atom charges among
the anion series (2.751 to 2.961) are somewhat greater than that of free XeO (2.724), whereas
3
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the O atom charges (O ; −1.073 to −1.037 and O ; −1.030 to −0.892) are in better agreement with
b
t
those of free XeO (−0.908).
3
Second orderꢀperturbation theory of the Fock matrix indicates the greatest twoꢀelectron
donorꢀacceptor stabilization energies correspond to donation of the halogen atom valence
electron lone pair (LP) densities to the σ*Xe−O antibonding orbitals that are trans to Xe=O bonds
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1
2
3
4
5
6
7
8
9
0
(Table S9). The ꢀꢀBr1 atom of 5 has three significant interactions between its LPs and the σ*Xe−O
orbitals. One LP interacts with two σ*Xe−O orbitals corresponding to stabilization energies of 18.5
–1
−1
and 4.8 kJ mol (total, 23.3 kJ mol ). A second LP interacts with one of the two σ*
orbitals
Xe−O
−1
which results in a stabilization energy of 18.7 kJ mol . Each ꢃ ꢀBr of 5 has five similar
3
–
1
interactions which provide a total stabilization energy of 45.6 (Br2) and 45.7 (Br3) kJ mol . In
contrast, the most significant stabilization energies for 7 result from the interaction of a single
–1
–1
bromine LP with one σ*Xe−O orbital (ꢀꢀBr2, 76.1 kJ mol ; ꢃ ꢀBr1, 47.4 kJ mol ). Similar donorꢀ
3
acceptor interactions occur in the chloroxenate anions which have smaller average donorꢀ
acceptor energies (Table S9). For example, for [N(CH ) ][Cl (XeO ) ], the analogous values (ꢀꢀ
3
4
4
3 4
–1
–1
Cl2, 72.3 kJ mol ; ꢃ ꢀCl1, 48.7 kJ mol ) show a similar trend. The XeꢀꢀꢀO secondary bonds
3
–1
have interaction energies of 14.2 (5), 14.4 (6), 14.7 (7), and 9.4 (8) kJ mol .
CONCLUSION
Room temperature and airꢀstable chloroxenate and bromoxenate salts have been synthesized and
3−
4−
structurally characterized. The [X (XeO ) ] and [X (XeO ) ] (X = Cl or Br) anions have cage
3
3 3
4
3 4
structures that are well isolated in their crystal lattices and provide the first isolable examples of
stable Xe−Br bonds and rare examples of Xe−Cl bonds. They currently provide the only
examples of nobleꢀgas anions that have cage structures. All four salts are airꢀstable at room
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temperature, which is seldom encountered for nobleꢀgas compounds, but are explosive when
thermally and/or mechanically shocked. The Xe−Br and Xe−Cl bonds are essentially nonꢀ
covalent and electrostatic in nature and are stronger than the Xe–N bonds reported for the
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alkylnitrile adducts of XeF6 and XeO3. The halogenꢀxenon bonds of the cage haloxenate
anions may be viewed as σꢀhole bonds in which the halogen atoms are LP donors and the σ*Xe−O
orbitals are LP acceptors. Thus far, attempts to synthesize iodoxenate anions have failed because
−
iodide is more readily oxidized than chloride or bromide, and forms IO .
3
EXPERIMENTAL SECTION
Caution! Solid XeO is an extremely shockꢀsensitive, highly energetic material. Every effort
3
should be made to avoid formation of the solid. Although the chloroꢀ and bromoxenate salts are
reported to be airꢀstable in this work, on one occasion, compound 2 detonated when rapidly
warmed to room temperature, whereas compound 1 was shown to be very shock and friction
sensitive towards deflagration. The analogous chloroxenate salts, 3 and 4, are more stable than
their bromine analogues, but are also sensitive to thermal and mechanical shock and likewise
require careful handling procedures. The syntheses should not be carried out on scales greater
than 100 mg. Reaction vessels made of glass or other materials that shatter to produce sharp
shards should be avoided and appropriate protective equipment used (face shields, blast shields,
leather gloves, and ear protection). Xenon hexafluoride is a strong oxidizer which can detonate
on contact with organic materials. Hydrofluoric acid is highly toxic and corrosive. Aqueous HF
and aHF must therefore be handled using appropriate protective gear with immediate access to
4
3ꢀ45
proper treatment procedures.
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Apparatus and Materials. (a) General. All volatile, airꢀsensitive, materials were handled on
vacuum lines constructed of glass, Teflon, nickel, stainless steel, and FEP (hexafluoropropyleneꢀ
tetrafluoroethylenecopolymer) fluoroplastic. Preparative work was carried out in reaction vessels
constructed from ¼ꢀin. o.d. lengths of FEP tubing which was heatꢀsealed at one end, flared at the
other end, and connected through a 45° SAE flare nut to a KelꢀF (chlorotrifluoroethylene
polymer) valve to form a compression seal. Reaction tubes were rigorously dried under dynamic
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vacuum and passivated for ca. 8 h with 1 atm of F gas. Freonꢀ114 (1,2ꢀdichloroꢀ1,1’,2,2’ꢀ
2
tetrafluoroethane) was dried over P O . Acetonitrile (Caledon, HPLC grade) was purified and
2
5
46
dried using the literature procedure and CH CH CN (Aldrich, 99%) was dried over CaH and
3
2
2
distilled under static vacuum onto 4 Å molecular sieves. Both nitriles were stored over 4 Å
molecular sieves in glass vacuum vessels equipped with J. Young Teflon/glass valves until used.
Tetraethylammonium bromide (Aldrich, 99%) and [N(CH ) ]Br (Eastman, 99%) were dried
3
4
under dynamic vacuum at 20 °C whereas [N(C H )]Cl (Aldrich, 99%), and [N(CH ) ]Cl
2
5
3 4
(Eastman, 99%) were used as received.
(b) Xenon hexafluoride. Xenon hexafluoride was prepared by the reaction of Xe (99.995%, Air
Products and Chemicals) and F (98+%, Air Products and Chemicals) using a procedure similar
2
4
7
to that described by Malm and Chernick. Small amounts of XeF impurity, identified by weak
4
−1
Raman bands at 502 and 543 cm , did not interfere with the synthesis of XeO because XeF
3
4
32
undergoes disproportion to XeO in its reaction with H O.
3
2
(c) Preparation of XeO . (i) Method 1: Xenon hexafluoride (27.2 mg, 0.111 mmol) was
3
transferred under static vacuum at −196 °C into a ¼ꢀin. FEP reactor. Freonꢀ114 (ca. 0.5 mL) was
vacuum distilled onto XeF at −196 °C, the reactor was warmed to room temperature, whereupon
6
XeF dissolved to form a bright yellow solution. Acetonitrile (ca. 0.5 mL) was vacuum distilled
6
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into and frozen in the top portion of the reaction vessel at −196 °C. The reactor was allowed to
warm to −40 °C and the contents were carefully mixed by allowing the XeF to diffuse into the
6
upper CH CN layer. Three equivalents of H O (6.0 mg, 0.33 mmol) were added to the reaction
3
2
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vessel at 0 °C by use of a microsyringe. The reaction mixture was slowly warmed to 20 °C and
thoroughly mixed. A fine white powder (O Xe(NCCH ) ) was obtained upon removal of
3
3 2
volatiles under dynamic vacuum at −40 to −30 °C. Acetonitrile (ca. 0.5 mL) was vacuum
distilled into the top portion of the reactor at −78 °C (Caution! To avoid detonation, never
rapidly cool the reactor significantly below −78 °C). The reactor was warmed to −40 °C
whereupon the solid dissolved to form a clear, colorless solution.
(ii) Method 2: Xenon hexafluoride (1.689 g, 6.886 mmol) was transferred, under static vacuum,
into a ½ꢀin. o.d. FEP Uꢀtube. Using a flow of dry nitrogen gas, XeF vapor was swept into a 100
6
mL FEP bottle containing water (20 mL) while stirring with a Teflon coated stir bar. Solid XeO3
was obtained by allowing aliquots of the resulting XeO /HF solution to evaporate on FEP trays
3
inside a fume hood. Solid XeO can only be reliably obtained if the relative humidity is below 30%
3
32
at 20 °C. Once a dry solid had been obtained, it was carefully redissolved in dry CH CN.
3
Caution! Xenon trioxide will occasionally detonate upon addition of dry CH CN.
3
(d) Syntheses of [N(C H ) ] [Br (XeO ) ], 1 and 1·2CH CN. Tetraethylammonium bromide
2
5 4 3
3
3 3
3
(
23.4 mg, 0.11 mmol) was dissolved in 0.2 mL of CH CN and was slowly added to a CH CN
3
3
solution of XeO at −78 °C. The frozen solutions were warmed to −44 °C, which resulted in
3
melting and slow diffusion of the solutions into one another. Large colorless blockꢀshaped
crystals of 1ꢂ2CH CN formed over a 6 h period. Crystals of 1ꢂ2CH CN readily lose CH CN at
3
3
3
room temperature to form 1, a light yellow powder.
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(
e) Syntheses of [N(CH ) ][Br (XeO ) ], 2 and 2·xCH CN. Solid XeO (12.4 mg, 0.0692
3
4
4
3 4
3
3
mmol) was carefully dissolved in ca. 0.5 mL of CH CN and transferred into a ¼ꢀin. o.d. FEP
3
reaction tube and cooled to −78 °C. A solution of [N(CH ) ]Br (10.5 mg, 0.0682 mmol) in ca.
3
4
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0
.5 mL of CH CN was added to the reactor. The frozen solutions were warmed to −40 °C,
3
which resulted in melting and slow diffusion of the solutions into one another. Very fine needleꢀ
shaped crystals of 2ꢂxCH CN formed which proved to be unsuitable for singleꢀcrystal Xꢀray
3
diffraction. The reactor and contents were warmed to room temperature to effect dissolution and
then rapidly cooled to –40 °C, which resulted in the formation of a fine microcrystalline
precipitate. The needleꢀshaped crystals and the precipitate were shown to be identical by Raman
spectroscopy, showing bands that are attributable to CH CN. The needleꢀshaped crystals and
3
microcrystalline precipitate therefore corresponded to 2 coꢀcrystallized with CH CN (2ꢂxCH CN).
3
3
Redissolution and crystallization of the precipitate from CH CN at 0 °C led to the formation of
3
wellꢀdefined plateꢀshaped crystals which were suitable for Xꢀray crystallography and gave a
Raman spectrum that was identical to that of the needleꢀshaped crystals except for several bands
which exhibited small frequency shifts and the absence of CH CN solvent bands. The crystalline
3
compounds described in this section were colorless.
(f) Synthesis of [N(C H ) ] [Cl (XeO ) ], 3. Tetraethylammonium chloride (8.5 mg, 0.051
2 5 4 3 3 3 3
mmol) was loaded into a ¼ꢀin. o.d. FEP reactor. Approximately 0.2 mL of CH CN was vacuum
3
distilled into the reaction vessel at −196 °C. The reactor was warmed to room temperature and
the contents were mixed to give a clear, colorless solution. The solution was frozen at −50 °C
and a solution of XeO in CH CN was pipetted into the reactor. The latter solution had been
3
3
freshly prepared by careful dissolution of solid XeO (9.1 mg, 0.051 mmol) in ca. 0.1 mL of
3
CH CN. The reactor was warmed to −40 °C which resulted in melting and slow diffusion of the
3
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solutions. After 2 h, large, colorless, blockꢀshaped crystals of 3 formed at the interface of the two
solutions. Acetonitrile was removed under vacuum between −40 and −30 °C.
(g) Synthesis of [N(CH ) ] [Cl (XeO ) ], 4. Tetramethylammonium chloride (5.8 mg, 0.053
3
4 4
4
3 4
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mmol) was mixed with ca. 0.2 mL of CH CN in an FEP reaction tube. Water (0.1 mL) was
3
added to the reactor and the crystalline powder was completely dissolved at room temperature.
An aqueous solution of hydrolyzed XeF (XeO /HF 0.243 mL) was allowed to evaporate on an
6
3
FEP tray inside a fume hood to give pure solid XeO (9.4 mg, 0.052 mmol). The XeO was
3
3
carefully dissolved in 0.2 mL of CH CN and the solution was mixed with the [N(CH ) ]Cl
3
3 4
solution at 0 °C. Slow solvent evaporation resulted in the growth of clear, colorless needleꢀ
shaped crystals of 4.
X−ray Crystallography. (a) Crystal Mounting. Single crystals of 1ꢂ2CH CN and 2 were
3
mounted by carefully pouring crystalline samples from the FEP vessels used for crystal growth
into an aluminum cold trough that had been cooled to and maintained at −100 ±5 °C by a cold
4
8
stream of dry nitrogen gas as previously described. Crystals of compounds 3 and 4 were
selected and mounted from polystyrene Petri dishes at room temperature in the atmosphere.
Crystals for structure determination used in the present study were mounted on a goniometer
using perfluorinatedꢀpolyether oil (Fomblin Zꢀ25) on the tip of a dualꢀthickness polymer loop
TM
(MicroMount;
MiTeGen, 200ꢀ400 ꢃm) and had the dimensions 0.10 x 0.25 x 0.54
3
(
1ꢂ2CH CN), 0.11 x 0.25 x 0.34 (2), and 0.06 x 0.26 x 0.33 (3), and 0.060 x 0.11 x 0.35 mm (4).
3
(b) Collection and Reduction of X-ray Data. Crystals were centered on a Bruker SMART
APEX II diffractometer equipped with an APEX II 4K CCD (chargeꢀcoupled device) area
detector and a tripleꢀaxis goniometer controlled by the APEX II Graphical User Interface (GUI)
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software. A Bruker Triumph curved crystal monochromator was used with a Mo Kα (λ =
0
.71073 Å) Xꢀray source. The crystalꢀtoꢀdetector distance was 4.954 cm for 1ꢂ2CH CN, 2, 3, and
3
4
. Data collections were carried out in 512 x 512 pixel mode using 2 x 2 pixel binning.
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Processing of the raw data was done by use of the APEX II GUI software. The SADABS
program was used for scaling the diffraction data. Although crystals of
[
N(CH ) ] [Br (XeO ) ]ꢂxCH CN were obtained, they were unsuitable for a crystal structure
3 4 4 4 3 4 3
determination. The unit cell was indexed as monoclinic with cell dimensions a = 8.382(3) Å, b =
3
12.466(7) Å, c = 33.260(7) Å, β = 92.94(3)°, and V = 3470.6(9) Å .
51
(
c) Structure Solutions and Refinements. The XPREP program was used to confirm unit
cell dimensions and the crystal lattices. Compounds 1ꢂ2CH CN and 2 were solved in the
3
monoclinic space groups Cc and P2 /n, respectively. Compound 3 was initially solved in the
1
+
Pmna space group and displayed a high degree of disorder in the [N(C H )] cations. The
2
5
structure was then solved in the Pna2 space group and it was found that the Xe–Cl bonds were
1
significantly different; therefore the mirror plane is likely a pseudoꢀmirror plane, similar to that
observed in 1ꢂ2CH CN. The cations still exhibited some minor disorder as evidenced by their
3
elongated thermal ellipsoids. Because the cations were clearly discernable and well behaved, no
further attempts were made to model the cation disorder. Compound 4 was solved in the triclinic
5
2
1
space group P . The Olex2 program was periodically used to visualize structures and test for
5
3
twinning. The PLATON program did not find additional symmetries. The thermal ellipsoids of
+
some atoms of the CH CN molecules in 1ꢂ2CH CN and the [N(C H )] cations in 3 are elongated
3
3
2
5
and suggest significant degrees of thermal motion.
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Raman Spectroscopy. Raman spectra were recorded on a Bruker RFS 100 FTꢀRaman
−
1
spectrometer using 1064ꢀnm excitation, 300 mW laser power, and ±0.5 cm resolution as
4
8
previously described.
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Computational Details. The energyꢀminimized geometries, with all frequencies real, were
3−
3−
calculated for [Br (XeO ) ]
(5), [Cl (XeO ) ]
(6), [N(CH ) ] [Br (XeO ) ] (7), and
3 4 4 4 3 4
3
3 3
3
3 3
[
N(CH ) ] [Cl (XeO ) ] (8) using Def2ꢀTZVPD (Xe, Br, Cl, O) and 6ꢀ31+G (N, C, H) basis sets
3 4 4 4 3 4
and the B3LYP method. Basis sets were obtained from the EMSL Basis Set Exchange
5
4
(https://bse.pnl.gov/bse/portal). Quantumꢀchemical calculations were carried out using the
5
5
Gaussian 09 program for geometry optimizations, vibrational frequencies, and intensities. The
5
6
program GaussView was used to visualize the vibrational displacements and optimized
geometries of the anions. Natural bond orbital analyses were carried out by use of the NBO
57
program (version 6.0) implemented in Gaussian 09.
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the ACS Publications website at DOI:
XXXX.
Views of [N(C H ) ] [Br (XeO ) ]ꢂ2CH CN (1ꢂ2CH CN) [N(CH ) ] [Br (XeO ) ] (2),
2
5 4 3
3
3 3
3
3
3 4 4
4
3 4
[
N(C H ) ] [Cl (XeO ) ] (3), and [N(CH ) ] [Cl (XeO ) ] (4) (Figures S1–S4); bond
2 5 4 3 3 3 3 3 4 4 4 3 4
lengths and angles for 1ꢂ2CH CN, 2, 3, and 4 (Table S1); Raman spectra of 1ꢂ2CH CN,
3
3
2ꢂxCH CN, 3, and 4
(Figures S5–S9); vibrational frequencies and assignments (Tables
3
3–
3–
S2–S7); calculated gasꢀphase structures of [Br (XeO ) ] (5), [Cl (XeO ) ] (6),
3
3 3
3
3 3
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[
N(CH ) ] [Br (XeO ) ] (7), and [N(CH ) ] [Br (XeO ) ] (8) (Figures S10–S13); natural
3
4 4
4
3 4
3 4 4
4
3 4
population analysis (NPA) charges, Wiberg valencies, and Wiberg bond indices (Table S8);
selected values from the second order perturbation theory analysis of the Fock matrix
0
1
2
3
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3
4
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8
9
0
3–
(Table S9); atomic coordinates for the calculated gasꢀphase structures of [Br (XeO ) ] (5),
3
3 3
3–
[Cl (XeO ) ] (6), [N(CH ) ] [Br (XeO ) ] (7), and [N(CH ) ] [Br (XeO ) ] (8) (Tables
3
3 3
3 4 4
4
3 4
3 4 4
4
3 4
S10–S13). Atomic coordinates and other relevant crystallographic information for
compounds 1ꢂ2CH CN, 2, 3, and 4 are deposited with the Cambridge Crystallographic
3
Database Centre (CCDC); deposition numbers CCDC 1540181, 1540182, 1540183, and
1
540184, respectively.
AUTHOR INFORMATION
Corresponding Author
*
schrobil@mcmaster.ca
Notes
The authors declare no competing financial interests.
ACKNOWLEDGEMENTS
This paper is dedicated to the memory of George A. Olah. We thank the Natural Sciences and
Engineering Research Council of Canada (NSERC) for support in the form of a Discovery Grant
(G.J.S.) and for an Alexander Graham Bell CGSꢀD scholarship (J.T.G.) and the computational
resources provided by SHARCNet (Shared Hierarchical Academic Research Computing
Network; www.sharcnet.ca). We thank Dr. James Britten for advice relating to the solution of the
structure of 3. We thank Dr. Hélène P. A. Mercier for her helpful advice relating to the quantumꢀ
chemical calculations and assistance with the vibrational assignments.
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REFERENCES
(1) Schrobilgen, G. J.; Brock, D. S.; Mercier, H. P. A. Noble‐Gas Compounds. In KirkꢀOthmer
Encyclopedia of Chemical Technology, 5th Ed., Wiley & Sons: Hoboken, NJ, 2012; pp 1–
2
1.
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(
(
2) Smith, G. L.; Mercier, H. P. A.; Schrobilgen, G. J. Inorg. Chem. 2011, 50, 12359–12373.
3) Koppe, K.; Haner, J.; Mercier, H. P. A.; Frohn, H.ꢀJ.; Schrobilgen, G. J. Inorg. Chem. 2014,
53, 11640–11661.
(4) Seidel, S.; Seppelt, K. Science 2000, 290, 117–118.
(5) Stein, L.; Norris, J. R.; Downs, A. J.; Minihan, A. R. J. Chem. Soc., Chem. Commun. 1978,
1
2, 502–504.
(6) Hwang, I. C.; Seidel, S.; Seppelt, K. Angew. Chem. Int. Ed. 2003, 42, 4392–4395.
(7) Frohn, H.ꢀJ.; Schroer, T.; Henkel, G. Angew. Chem. Int. Ed. 1999, 38, 2554–2556.
(8) Seidel, S.; Seppelt, K. Angew. Chem. Int. Ed. 2001, 40, 4225–4227.
(9) Pan, S.; Moreno, D.; Ghosh, S.; Chattaraj, P. K.; Merino, G. J. Comput. Chem. 2016, 37,
2
26–236.
(
(
10) Borocci, S.; Giordani, M.; Grandinetti, F. J. Phys. Chem. A 2014, 118, 3326–3334.
11) Pan, S.; Moreno, D.; Cabellos, J. L.; Romero, J.; Reyes, A.; Merino, G.; Chattaraj, P. K. J.
Phys. Chem. A 2013, 118, 487–494.
(12) Mück, L.A.; Timoshkin, A.Y; Hopffgarten, M.V.; Frenking, G. J. Am. Chem. Soc. 2009,
1
31, 3942–3949.
(
(
13) Ghosh, A.; Manna, D.; Ghanty, T. K. Phys. Chem. Chem. Phys. 2016, 18, 12289–12298.
14) Pettersson, M.; Lundell, J.; Khriachtchev, L.; Isoniemi, E.; Räsänen, M. J. Am. Chem. Soc.
1998, 120, 7979–7980.
(15) Cipollini, R.; Grandinetti, F. J. Chem. Soc., Chem. Commun. 1995, 7, 773–774.
(16) Li, J.; Bursten, B. E.; Liang, B.; Andrews, L. Science 2002, 295, 2242–2245.
(17) Willett, R. D.; Peterson, S. W.; Coyle, B. A. J. Am. Chem. Soc. 1977, 99, 8202–8207.
(18) LaBonville, P.; Ferraro, J. R.; Spittler, T.M. J. Chem. Phys. 1971, 55, 631–640.
(19) Jaselskis, B.; Huston, J. L.; Spittler, T. M. J. Am. Chem. Soc. 1969, 91, 1874–1875.
(20) Hodgson, D.; Ibers, J. A. Inorg. Chem. 1969, 8, 326−331.
(
(
(
(
21) Perlow, G. J.; Hiroyuki Y. J. Chem. Phys. 1968, 49, 1474–1478.
22) Howard Jr, W. F.; Andrews, L. J. Am. Chem. Soc. 1974, 96, 7864–7868.
23) Liao, M. S.; Zhang, Q. E. J. Phys. Chem. A 1998, 102, 10647–10654.
24) Pettersson, M.; Lundell, J.; Räsänen, M. J. Chem. Phys. 1995, 102, 6423–6431.
(25) Tsuge, M.; Berski, S.; Stachowski, R.; Räsänen, M.; Latajka, Z.; Khriachtchev, L. J. Phys.
Chem. A 2012, 116, 4510–4517.
(
(
(
(
26) Searles, S. K.; G. A. Hart. Appl. Phys. Lett. 1975, 27, 243–245.
27) Bock, H.; Scherer, H.; Tyrra, W.; Naumann, D. J. Fluorine Chem. 2006, 127, 1440–1445.
28) Jaselskis, B. Rec. Chem. Prog. 1970, 31, 103–132.
29) Christe, K. O. Angew. Chem. Int. Ed. 2001, 40, 1419–1421.
(30) Aleinikov, N. N.; Korsunskii, B. L.; Dubovitskii, F. I. Russ. Chem. Bull. 1974, 23, 254–
56.
2
(
(
31) Jaselskis, B.; Warriner, J. P. J. Am. Chem. Soc. 1969, 91, 210–211.
32) Goettel, J. T.; Schrobilgen, G. J. Inorg. Chem. 2016, 55, 12975–12981 and references
therein.
25
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Page 26 of 28
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2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
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5
5
5
5
5
5
5
5
6
(
33) Goettel, J. T.; Matsumoto, K.; Mercier, H. P. A.; Schrobilgen, G. J. Angew. Chem. Int. Ed.
2
016, 55, 13780–13783.
(34) Lutz, H. D.; Christian, H.; Eckers, W. Spectrochim. Acta Mol. Biomol. Spectrosc. 1985, 41,
637–642.
(
(
(
(
35) Krebs, B.; Paulat, V. Acta Crystallogr., Sect. B: Struct. Sci. 1976, 32, 1470–1476.
36) Rheingold, A. L.; Uhler, A. D.; Landers, A. G. Inorg. Chem. 1983, 22, 3255–3258.
37) Bondi, A. J. Phys. Chem. 1964, 68, 441–451.
38) Chen, X.; Rickard, M.A.; Hull Jr, J.W.; Zheng, C.; Leugers, A.; Simoncic, P. Inorg. Chem.
2010, 49, 8684–8689.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(39) Kabisch, G. J. Raman Spectrosc. 1980, 9, 279–285.
(40) De Beer, W. H. J.; Heyns, A. M. Spectrochim. Acta Mol. Biomol. Spectrosc. 1981, 37,
1
099–1107.
(41) Claassen, H. H.; Knapp, G. J. Am. Chem. Soc. 1964, 86, 2341–2342.
(42) Matsumoto, K.; Haner, J.; Mercier, H. P. A.; Schrobilgen, G.J. Angew. Chem. Int. Ed. 2015,
5
4, 14169–14173.
(43) Bertolini, J. C. J. Emerg. Med. 1992, 10, 163–168.
(44) Peters, D.; Miethchen, R. J. Fluorine Chem. 1996, 79, 161–165.
(45) Segal, E. B. Chem. Health Saf. 2000, 7, 18–23.
(
(
(
(
46) Winfield, J. M. J. Fluorine Chem. 1984, 25, 91–98.
47) Malm, J. G.; Chernick, C. L. Inorg. Synth. 1966, 8, 258–260.
48) Gerken, M.; Dixon, D. A.; Schrobilgen, G. J. Inorg. Chem. 2000, 39, 4244−4255.
49) APEX2, release v2014.9ꢀ0; Bruker AXS Inc.: Madison, WI, 1995.
(50) Sheldrick, G. M. SADABS (Siemens Area Detector Absorption Corrections), version 2.03;
Siemens Analytical Xꢀray Instruments, Inc.: Madison, WI, 1999.
(51) Sheldrick, G. M. SHELXTLꢀPlus, release 5.1; Siemens Analytical Xꢀray Instruments, Inc.:
Madison, WI, 1998.
(52) Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A. K.; Puschmann, H., J. Appl.
Cryst. 2009, 42, 339−341.
(53) Spek, A. L. J. Appl. Cryst. 2003, 36, 7−13.
(
54) Basis sets were obtained from the Extensible Computational Chemistry Environment Basis
Set Database, version 2/25/04, as developed and distributed by the Molecular Science
Computing Facility, Environmental and Molecular Science Laboratory, which is part of the
Pacific Northwest Laboratory, P.O. Box 999, Richland, WA 99352.
(
55) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman,
J.R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.;
Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada,
M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.;
Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.;
Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.;
Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi,
M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.;
Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.;
Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G.
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A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.; Foresman, J.
B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision D.01; Gaussian, Inc:
Wallingford, CT, 2009.
(
56) GaussView, version 3.0; Gaussian Inc.: Pittsburgh, PA, 2003.
(57) NBO 6.0. Glendening, E. D.; Badenhoop, J. K.; Reed, A. E.; Carpenter, J. E.; Bohmann, J.
A.; Morales, C. M.; Landis, C. R.; Weinhold, F. Theoretical Chemistry Institute,
University of Wisconsin, Madison, 2013.
10
11
12
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14
15
16
17
18
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