Syntheses, Raman Spectra, and X-ray crystal structures of [XeF 5][μ-F(OsO3F2)2] and [M][OsO 3F3] (M = XeF5+, Xe 2F11+)

Article abstract of DOI:10.1021/ic100062x

Stoichiometric amounts of XeF₆ and (OsO₃F ₂)_∞ react at 25-50 °C to form salts of the known XeF₅⁺ and Xe₂F₁₁⁺ cations, namely, [XeF₅][μ-F(OsO₃F₂) ₂], [XeF₅][OsO₃F₃], and [Xe ₂F₁₁][OsO₃F₃]. Although XeF ₆ is oxophllic toward a number of transition metal and main-group oxides and oxide fluorides, fluoride/oxide metathesis was not observed. The series provides the first examples of noble-gas cations that are stabilized by metal oxide fluoride anions and the first example of a μ-F(OsO ₃F₂)₂ salt. Both [XeF₅][μ- F(OsO₃F₂)₂] and [Xe₂F ₁₁][OsO₃F₃] are orange solids at room temperature. The [XeF₅][OsO₃F₃] salt is an orange liquid at room temperature that solidifies at 5-0°C. When the salts are heated at 50 °C under 1 atm of N₂ for more than 2 h, significant XeF₆ loss occurs. The X-ray crystal structures (-173 °C) show that the salts exist as discrete ion pairs and that the osmium coordination spheres in OsO₃F_3- and μ-F(OsO ₃F₂)_2- are pseudo-octahedral OsO ₃F₃-units having facial arrangements of oxygen and fluorine atoms. The μ-F(OsO₃F₂)_2- anion Is comprised of two symmetry-related OsO₃F₂-groups that are fluorine-bridged to one another. Ion pairing results from secondary bonding interactions between the fluorine/oxygen atoms of the anions and the xenon atom of the cation, with the Xe...F/O contacts occurring opposite the axial fluorine and from beneath the equatorial XeF₄-planes of the XeF ₅ and Xe₂F₁₁ cations so as to avoid the free valence electron lone pairs of the xenon atoms. The xenon atoms of [XeF ₅][μ-F(OsO₃F₂)₂] and [Xe ₂F₁₁][OsO₃F₃] are nine-coordinate and the xenon atom of [XeF₅][OsO₃F₃] is eight-coordinate. Quantum-chemical calculations at SVWN and B3LYP levels of theory were used to obtain the gas-phase geometries, vibrational frequencies, and NBO bond orders, valencies, and NPA charges of the ion pairs, [Xe ₂F₁₁][OsO₃F₃], [XeF ₅][OsO₃F₃], and [XeF₅][μ- F(OsO₃F₂)₂,] as well as those of the free ions, Xe₂F₁₁⁺, XeF₅^-, OsO ₃F₃^-, and μ-F(OsO₃F ₂)₂^-, The Raman spectra (-150 °C) of the salts have been assigned based on the ion pairs observed in the crystal structures and the calculated vibrational frequencies and intensities of the gas-phase ion pairs.

Full text of DOI:10.1021/ic100062x

Inorg. Chem. 2010, 49, 3501–3515 3501
DOI: 10.1021/ic100062x
Syntheses, Raman Spectraþ, and X-ray Crystal Structures of [XeF5][μ-F(OsO3F2)2]
þ
and [M][OsO3F3] (M = XeF5 , Xe2F11
)
ꢀ ꢁ
Michael J. Hughes, Helene P. A. Mercier, and Gary J. Schrobilgen*
Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1, Canada
Received January 11, 2010
þ
Stoichiometric amounts of XeF6 and (OsO3F2)¥ react at 25-50 ꢀC to form salts of the known XeF5þ and Xe2F11
cations, namely, [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3]. Although XeF6 is oxophilic toward a
number of transition metal and main-group oxides and oxide fluorides, fluoride/oxide metathesis was not observed.
The series provides the first examples of noble-gas cations that are stabilized by metal oxide fluoride anions and the
first example of a μ-F(OsO3F2)2- salt. Both [XeF5][μ-F(OsO3F2)2] and [Xe2F11][OsO3F3] are orange solids at room
temperature. The [XeF5][OsO3F3] salt is an orange liquid at room temperature that solidifies at 5-0 ꢀC. When the salts
are heated at 50 ꢀC under 1 atm of N2 for more than 2 h, significant XeF6 loss occurs. The X-ray crystal structures
(-173 ꢀC) show that the salts exist as discrete ion pairs and that the osmium coordination spheres in OsO3F3- and
μ-F(OsO3F2)2- are pseudo-octahedral OsO3F3-units having facial arrangements of oxygen and fluorine atoms. The
μ-F(OsO3F2)2- anion is comprised of two symmetry-related OsO3F2-groups that are fluorine-bridged to one another.
Ion pairing results from secondary bonding interactions between the fluorine/oxygen atoms of the anions and the
xenon atom of the cation, with the Xe F/O contacts occurring opposite the axial fluorine and from beneath the
3 3 3
þ
þ
equatorial XeF4-planes of the XeF5 and Xe2F11 cations so as to avoid the free valence electron lone pairs of
the xenon atoms. The xenon atoms of [XeF5][μ-F(OsO3F2)2] and [Xe2F11][OsO3F3] are nine-coordinate and the
xenon atom of [XeF5][OsO3F3] is eight-coordinate. Quantum-chemical calculations at SVWN and B3LYP levels of
theory were used to obtain the gas-phase geometries, vibrational frequencies, and NBO bond orders, valencies, and
NPA charges of the ion pairs, [Xe2F11][OsO3F3], [XeF5][OsO3F3], and [XeF5][μ-F(OsO3F2)2], as well as those of the
free ions, Xe2F11þ, XeF5þ, OsO3F3-, and μ-F(OsO3F2)2-. The Raman spectra (-150 ꢀC) of the salts have been
assigned based on the ion pairs observed in the crystal structures and the calculated vibrational frequencies and
intensities of the gas-phase ion pairs.
Introduction
prior to the present study, was the only example of a Xe(VI)/
Os(VIII) compound.5 Failure to abstract a fluoride ion from
XeOF4 to form a XeOF3þ salt of OsO3F3- is in accordance
with the lower gas-phase fluoride ion affinity of OsO3F2
(348.5 kJ mol-1) relative to that of SbF5 (495.0 kJ mol-1).6
Moreover, only XeOF3þ salts derived from one of the strong-
est fluoride ion acceptors known, SbF5, have been synthe-
sized, namely, [XeOF3][SbF6]7-9 and [XeOF3][Sb2F11].7,10,11
The fluoride ion acceptor strength of (OsO3F2)¥ toward
Polymeric (OsO3F2)¥ has been previously shown to behave
as a fluoride-ion acceptor toward strong fluoride ion donors,
-
forming the OsO3F3 anion as its Kþ,1-3 Csþ,1-3 Agþ,1
Rbþ,2 Naþ,2 NOþ,4 and N(CH3)4þ 4 salts. The infrared and
-
Raman spectra of OsO3F3 have been assigned to the fac-
isomer (C3v symmetry)2,4 and an extended X-ray absorption
fine structure (EXAFS) study also assigned a facial geometry
to the OsO3F3- anion in its Kþ salt.3 The single-crystal X-ray
structure of [N(CH3)4][OsO3F3]4 also established that the
OsO3F3- anion of this salt has a facial geometry.
(5) Hughes, M. J.; Mercier, H. P. A.; Schrobilgen, G. J. Inorg. Chem.
2009, 48, 4478–4490.
(6) Christe, K. O.; Dixon, D. A. Recent Progress on the Christe/Dixon
Quantitative Scale of Lewis Acidity. Presented at the 92nd Canadian Society
for Chemistry Conference, Hamilton, Ontario, May-June 2009.
(7) Gillespie, R. J.; Landa, B.; Schrobilgen, G. J. Inorg. Chem. 1976, 15,
1256–1263.
A recent study of the reaction of (OsO3F2)¥ with XeOF4
has led to the molecular adduct, (OsO F ) 2XeOF which,
3
3
2 2
4
*To whom correspondence should be addressed. E-mail: schrobil@
mcmaster.ca.
(1) Hepworth, M. A.; Robinson, P. L. J. Inorg. Nucl. Chem. 1957, 4, 24–
29.
(8) Schrobilgen, G. J.; Holloway, J. H.; Granger, P.; Brevard, C. Inorg.
Chem. 1978, 17, 980–987.
(2) Jones, P. J.; Levason, W.; Tajik, M. J. Fluorine Chem. 1984, 25, 195–
201.
(3) Brewer, S. A.; Brisdon, A. K.; Holloway, J. H.; Hope, E. G.; Levason,
W.; Ogden, J. S.; Saad, A. K. J. Fluorine Chem. 1993, 60, 13–17.
(4) Gerken, M.; Dixon, D. A.; Schrobilgen, G. J. Inorg. Chem. 2000, 39,
4244–4255.
(9) Mercier, H. P. A.; Sanders, J. C. P.; Schrobilgen, G. J.; Tsai, S. S.
Inorg. Chem. 1993, 32, 386–393.
(10) Gillespie, R. J.; Landa, B.; Schrobilgen, G. J. J. Chem. Soc., Chem.
Commun. 1972, 607–609.
(11) McKee, D. E.; Adams, C. J.; Zalkin, A.; Bartlett, N. J. Chem. Soc.,
Chem. Commun. 1973, 26–28.
r
2010 American Chemical Society
Published on Web 02/25/2010
pubs.acs.org/IC

3502 Inorganic Chemistry, Vol. 49, No. 7, 2010
Hughes et al.
XeOF4
polar-covalent fluorides is diminished relative to that of gas-
phase OsO3F2 because the fluoride ion donor must be
sufficiently fluoro-basic to disrupt the Os---F---Os bridge
bonds of the polymeric solid-state structure of (OsO3F2)¥.12
In contrast, XeF6 is the strongest fluoride ion donor
among the binary fluorides of xenon,13 and forms a large
number of XeF5þ and Xe2F11þ salts with a variety of Lewis
acid fluorides having a wide range of fluoride ion acceptor
strengths (see Supporting Information for a comprehensive
list of known XeF5þ and Xe2F11þ salts and their references).
The XeF5 and Xe2F11 cations are extensively associated
with their anions through fluorine bridge contacts. In the
present study, the reactivity of (OsO3F2)¥ with the moder-
ately strong fluoride ion donor, XeF6, is investigated. The
syntheses and characterizations by Raman spectroscopy and
single-crystal X-ray diffraction of [XeF5][μ-F(OsO3F2)2],
[XeF5][OsO3F3], and [Xe2F11][OsO3F3] are described and
provide the first examples of noble-gas cations stabilized by
metal oxide fluoride anions. The X-ray crystal structures of
these strongly ion-paired salts and their Raman spectra are
compared within the series and with the gas-phase ion-pair
geometries and vibrational spectra that have been arrived at
by quantum-chemical calculations.
½XeF5ꢀ½μ-FðOsO3F2Þ2ꢀ þ 2XeOF4
ðOsO3F2Þ2 3 2XeOF4 þ XeF6 ð4Þ
When molten [XeF5][μ-F(OsO3F2)2] was cooled from
50 to 25 ꢀC over a period of 1 h, light orange, block-
shaped crystals of [XeF5][μ-F(OsO3F2)2] formed which
were suitable for single-crystal X-ray diffraction. The
Raman spectrum of the recrystallized compound was
identical to that of the bulk microcrystalline compound
used for recrystallization.
A 1:1 molar ratio of OsO3F2 and XeF6 was fused at
25 ꢀC, yielding an intense orange liquid that slowly
solidified at 0 ꢀC to give an orange crystalline mass that
corresponded to [XeF5][OsO3F3] (eq 5). The sample was
remelted and slowly cooled over a period of 1 h from 5 to
þ
þ
XeF6 þ OsO3F2
½XeF5ꢀ½OsO3F3ꢀ
0 ꢀC, forming light orange block-shaped crystals that
were suitable for single-crystal X-ray diffraction. The
Raman spectra of the initial crystalline solid and of the
remelted crystalline solid were identical.
ð5Þ
The reaction of (OsO3F2)¥ with two molar equivalents
of XeF6 yielded an orange, microcrystalline powder
corresponding to [Xe2F11][OsO3F3] (eq 6), which melted
at 40-45 ꢀC to give an intense orange liquid.
Results and Discussion
Syntheses and Crystal Growth of [XeF5][μ-F(OsO3F2)2],
[XeF5][OsO3F3], and [Xe2F11][OsO3F3]. The [XeF5]-
[μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3]
salts were synthesized by direct reaction of XeF6 and
(OsO3F2)¥ at temperatures ranging from 25 to 50 ꢀC,
and the extent of reaction was monitored by low-tem-
perature (-150 ꢀC) Raman spectroscopy.
A 2:1 molar ratio of OsO3F2 and XeF6 was allowed to
react at room temperature (25 ꢀC), initially forming an
orange liquid which solidified as the reaction progressed.
To ensure complete reaction, the resulting microcrystal-
line orange solid, [XeF5][μ-F(OsO3F2)2], was heated at
50 ꢀC for 1 h but showed no physical changes or change
in the Raman spectrum (eq 1). When dissolved in HF at
25 ꢀC, the fluoride ion affinity of HF was sufficient to
abstract a fluoride ion from μ-F(OsO3F2)2- to form
25 o
C
2XeF6 þ OsO3F2
½Xe2F11ꢀ½OsO3F3ꢀ ð6Þ
Cooling of the melt to 25 ꢀC resulted in crystalline
[Xe2F11][OsO3F3]. Crystalline [Xe2F11][OsO3F3], suitable
for single-crystal X-ray diffraction, was obtained by
heating a mixture of 4.6 equiv of XeF6 and 1 equiv of
OsO3F2 at 45 ꢀC, whereupon XeF6 melted and reacted
with OsO3F2 to form an intense orange liquid. Cooling of
the reaction mixture to 15 ꢀC over a period of 12 h resulted
in the growth of light orange needle-shaped crystals of
[Xe2F11][OsO3F3] and colorless block-shaped crystals of
XeF6. The latter was shown to be a monoclinic phase
(P21/c, Z = 32) of XeF615,16 based on its unit cell para-
meters. Crystals grown from the XeF6 melt had the same
unit cell parameters as crystals grown from a 2:1 stoichio-
metric mixture of XeF6/OsO3F2.
The salts, [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and
[Xe2F11][OsO3F3], are stable at room temperature for up
to 24 h; however, when heated at 50 ꢀC under ca. 1 atm of
dry N2 for periods exceeding 2 h, crystals of XeF6 sub-
limed out of the heated zone and condensed on the cooler
walls of the reaction vessel. Although XeF6 is oxophilic
toward a numberof metal oxidesand oxide fluorides,17-19
fluoride/oxide metathesis, indicated by XeOF4 formation
and strong Xe-O stretching bands at 902 and 908 cm-1 in
the solid,5 was not detected in the course of monitoring
the aforementioned syntheses by Raman spectroscopy.
50 o
C
2OsO3F2 þ XeF6
½XeF5ꢀ½μ-FðOsO3F2Þ2ꢀ ð1Þ
(OsO3F2)¥, XeF6, and F- nHF (eq 2). In HF solution,
3
XeF6 ionizes to XeF5þ and F- nHF (eq 3).14 In XeOF4
3
solvent at 25 ꢀC, [XeF5][μ-F(OsO3F2)2] reacted to form
(OsO F ) 2XeOF 5 and XeF6 (eq 4) which was verified
by Raman spectroscopy after removal of the solvent at
3
3
2 2
4
-40 ꢀC.
HF
½XeF5ꢀ½μ-FðOsO3F2Þ2ꢀ þ nHF
2OsO3F2 þ XeF6 þ F- nHF ð2Þ
3
HF
h
XeF5þ þ F- nHF
XeF6
ð3Þ
3
(15) Burbank, R. D.; Jones, G. R. Science 1971, 171, 485–487.
(16) Hoyer, S.; Emmler, T.; Seppelt, K. J. Fluorine Chem. 2006, 127, 1415–
1422.
(17) Mercier, H. P. A.; Schrobilgen, G. J. Inorg. Chem. 1993, 32, 145–151.
ꢂ
ꢀ
(18) Fele Beuermann, M.; Milicev, S.; Lutar, K.; Zemva, B. Eur. J. Solid
(12) Bougon, R.; Buu, B.; Seppelt, K. Chem. Ber. 1993, 126, 1331–1336.
(13) Bartlett, N.; Sladky, F. O. J. Am. Chem. Soc. 1968, 90, 5316–5317.
(14) Hyman, H. H.; Quarterman, L. A. In Noble-Gas Compounds; Hyman,
H. H., Ed.; University of Chicago Press: Chicago, 1963; pp 275-278.
State Inorg. Chem. 1994, 31, 545–556.
(19) Casteel, W. J.; Dixon, D. A.; LeBlond, N.; Lock, P. E.; Mercier,
H. P. A.; Schrobilgen, G. J. Inorg. Chem. 1999, 38, 2340–2358.

Article
Inorganic Chemistry, Vol. 49, No. 7, 2010 3503
Table 1. Summary of Crystal Data and Refinement Results for [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3]
[XeF5][μ-F(OsO3F2)2]
[XeF5][OsO3F3]
[Xe2F11][OsO3F3]
chem formula
space group
Os8O24F40Xe4
Pnma (62)
12.672(1)
11.444(1)
7.5818(7)
1099.6(2)
4
Os8O24F64Xe8
P42/n (86)
16.8876(3)
16.8876(3)
5.3414(2)
1523.3(1)
8
Os4O12F56Xe8
Pnma (62)
9.2479(3)
15.1769(5)
8.1192(2)
1139.46(6)
4
˚
a (A)
˚
b (A)
˚
c (A)
3
V (A )
˚
molecules/unit cell
mol wt (g mol-1
)
1633.40
4.819
4172.00
4.548
3067.20
4.470
calcd density (g cm-3
)
T (ꢀC)
-173
26.28
0.0273
0.0486
-173
21.24
0.0356
0.0729
-173
17.24
0.0249
0.0603
μ (mm-1
R1
wR2
)
a
b
P
P
P
P
a R1 is defined as ||Fo| - |Fc||/ |Fo| for I > 2σ(I). b wR2 is defined as { w(Fo2 - Fc2)2/ w(Fo2)2}1=2 for I > 2σ(I).
5
˚
X-ray Crystal Structures of [XeF5][μ-F(OsO3F2)2],
[XeF5][OsO3F3], and [Xe2F11][OsO3F3]. Details of data
collection parameters and other crystallographic infor-
mation are provided in Table 1. The bond lengths and
bond angles of [XeF5][μ-F(OsO3F2)2] are listed in Table 2
and those of [XeF5][OsO3F3] and [Xe2F11][OsO3F3] are
listed in Table 3. Crystal packing diagrams (Figures S1-
S3, Supporting Information) along with a brief discussion
of the packing arrangements are given in the Supporting
Information. The ion pairs of all three structures are well
isolated from one another (Figures 1a-3a), although an
(OsO F ) 2XeOF (1.927(5) A), the Os-F bonds of
3
3
2 2
4
the OsO3F3- and μ-F(OsO3F2)2- anions are elongated as
a result of increased negative charge on the oxygen ligands
of the anions. The terminal fluorine atoms of μ-F(OsO3F2)2
-
,
F(1)/F(1A) and Fþ(2)/F(2A), form bridge contacts to
xenon of the XeF5 cation, constraining the symmetry-
related OsO2F2-equatorial planes of μ-F(OsO3F2)2 so
-
that they are eclipsed. Although the Os(1)---F(3)---Os(1A)
bridge bond angle (155.5(1)o) is significantly bent, whicþh
allows the four fluorine ligands to chelate the XeF5
cation, it is significantly more open than in the re-
lated Os(VIII) compounds, (OsO3F2)¥ (143.9(2)o)12 and
inter-ion pair contact (O(1B) Xe(1)) occursinthe[Xe F ]-
3 3 3
2
11
[OsO3F3] structure, with long intermolecular contacts
between adjacent ion pairs in [XeF5][μ-F(OsO3F2)2],
[XeF5][OsO3F3], and [Xe2F11][OsO3F3] near the sums of
the van der Waals radii20 of the contacting atoms.
(OsO F ) 2XeOF (109(1)o),5 owing to the steric re-
3
3
2 2
4
quirements of the XeF5þ cation.
The geometrical parameters of the OsO3F3- anions in
the present study (Figures 2 and 3) are in good agreement
salts.
(a) OsO3F3 and μ-F(OsO3F2)2-. The primary coor-
with those reported for the Kþ 3 and N(CH3)4
-
þ 4
dination spheres of the osmium atoms in [XeF5]-
[μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3]
consist of three oxygen and three fluorine atoms in facial
arrangements, providing distorted octahedral environ-
ments around the osmium atoms (Figures 1-3). The
preference for the fac-trioxo arrangement has been pre-
The Os-O bond lengths are equal, within (3σ, for
[Xe2F11][OsO3F3] (1.703(2), 1.697(3) A) and [XeF5]-
˚
˚
[OsO3F3] (1.701(3), 1.701(3), 1.692(3) A), and are in good
agreement with the values reported for [K][OsO3F3]
˚
3
(1.698(2) A, EXAFS), [N(CH3)4][OsO3F3] (1.70(1)-
4
12
˚
˚
1.73(1) A), (OsO3F2)¥ (1.678(1)-1.727(1) A), and
5
viously discussed for other d0 osmium trioxo-species
(OsO F ) 2XeOF (1.684(6)-1.703(6) A). The Os-F
3
bond lengths of [Xe2F11][OsO3F3] (2.004(2), 2.001(2) A)
˚
3
2 2
4
- 4
such as (OsO3F2)¥,12 OsO3F3
,
(OsO F ) 2XeOF ,5
˚
3
3
2 2
4
and [OsO3F][HF][SbF6].21 The OsO3F2-groups of
μ-F(OsO3F2)2- are symmetry related, and therefore only
one OsO3F2-group is discussed.
and [XeF5][OsO3F3] (2.011(2), 2.006(2), 2.028(2) A) are
also in good agreement with each other, but are some-
what elongated compared to those of [N(CH3)4][OsO3F3]
˚
4
(1.97(1), 1.91(1), 1.94(1) A) and [K][OsO3F3] (1.919(15)
˚
The [XeF5][μ-F(OsO3F2)2] salt is the first example of
-
3
A), which is attributed to significant Xe F intra-ion
˚
the fluorine-bridged μ-F(OsO3F2)2 anion (Figure 1a).
3 3 3
The Os-O bond lengths are equal to within (3σ
(1.698(2), 1.701(2), 1.692(2) A) and are similar to those
pair contacts with the XeF5þ and Xe2F11þ cations (vide
˚
infra).
of the OsO3F3- anion (vide infra). The F(3) atom bridges
the OsO3F2-groups, resulting in a bridge bond length
The light atoms of OsO3F3- and μ-F(OsO3F2)2- form
relatively undistorted octahedral coordination spheres
about the osmium atoms (Figure S4, Supporting In-
formation) as shown by their nearest-neighbor interli-
gand atom contacts (Table S1, Supporting Information).
The displacements of the osmium atoms toward the
centroid of the three facial oxygen atoms are similar
to the metal atom displacements observed for other
Os(VIII) compounds, which have been previously dis-
˚
(Os(1)---F(3), 2.1179(5) A) that is similar to the Os---F
12
˚
bridge bond lengths in (OsO3F2)¥ (2.126(1), 2.108(1) A)
5
and (OsO F ) 2XeOF (2.117(5), 2.107(4) A). The
˚
3
3
2 2
4
Os-F(1) and Os-F(2) bond lengths (1.978(1) and
˚
1.962(1) A, respectively) are significantly shorter thaþn
-
the Os-F þbonds of the OsO3F3 anions in the Xe2F11
and XeF5 salts (vide infra). When compared with
other terminal Os-F bond lengths of the related
cussed in detail for (OsO3F2)¥,12 (OsO F ) 2XeOF ,5
3
3
2 2
4
12
- 4
˚
fluorine-bridged species (OsO3F2)¥ (1.879(1) A) and
and OsO3F3 .
(b) XeF5þ and Xe2F11þ. The XeF5þ cations of [XeF5]-
[μ-F(OsO3F2)] (Figure 1) and [XeF5][OsO3F3] (Figure 2)
are based on pseudo-octahedral AX5E VSEPR arrange-
ments of bond pairs (X) and lone pairs (E) which give rise
(20) Bondi, A. J. Phys. Chem. 1964, 68, 441–451.
(21) Gerken, M.; Dixon, D. A.; Schrobilgen, G. J. Inorg. Chem. 2002, 41,
259–277.

3504 Inorganic Chemistry, Vol. 49, No. 7, 2010
Hughes et al.
Table 2. Experimental and Calculated Geometrical Parameters for [XeF5][μ-F(OsO3F2)2]
calcdb
μ-F(OsO3F2)2
C2
-
þ
[XeF5][μ-F(OsO3F2)2]
XeF5
C2v
C4v
exptla
SVWNc
B3LYPd
SVWNc
B3LYPd
SVWNc
B3LYPe
˚
Bond Lengths (A)
Os(1)-F(1)
Os(1)-F(2)
Os(1)---F(3)
Os(1)-O(1)
Os(1)-O(2)
Os(1)-O(3)
1.978(1)
1.962(1)
2.1179(5)
1.698(2)
1.701(2)
1.692(2)
2.622(1)
2.663(1)
1.822(2)
1.848(1)
1.848(2)
1.852(2)
1.848(1)
1.975
1.975
2.115
1.712
1.712
1.708
2.461
2.461
1.890
1.922
1.916
1.916
1.922
1.980
1.980
2.147
1.690
1.690
1.690
2.643
2.644
1.881
1.898
1.902
1.902
1.898
1.919
1.908
2.121
1.729
1.730
1.723
1.927
1.925
2.157
1.701
1.702
1.699
Xe(1) F(1)
3 3 3
Xe(1) F(2)
3 3 3
Xe(1)-F(4)
Xe(1)-F(5)
Xe(1)-F(6)
Xe(1)-F(7)
Xe(1)-F(5A)
1.844
1.877
1.877
1.877
1.877
1.840
1.871
1.871
1.871
1.871
Bond Angles (deg)
F(1)-Os(1)-F(2)
F(1)-Os(1)---F(3)
F(1)-Os(1)-O(1)
F(1)-Os(1)-O(2)
F(1)-Os(1)-O(3)
F(2)-Os(1)---F(3)
F(2)-Os(1)-O(1)
F(2)-Os(1)-O(2)
F(2)-Os(1)-O(3)
F(3)---Os(1)-O(1)
F(3)---Os(1)-O(2)
F(3)--Os(1)-O(3)
O(1)-Os(1)-O(2)
O(1)-Os(1)-O(3)
O(2)-Os(1)-O(3)
75.71(6)
79.18(7)
160.07(7)
87.72(8)
91.39(8)
77.22(7)
88.99(7)
156.62(7)
94.56(8)
85.10(8)
83.62(8)
168.71(9)
102.72(9)
102.67(9)
102.34(9)
54.44(4)
136.53(6)
70.03(5)
130.36(5)
126.07(6)
71.09(6)
135.95(6)
68.19(6)
131.94(6)
71.81(6)
124.98(6)
77.96(5)
77.96(5)
79.7(1)
74.2
77.0
156.6
88.2
93.1
77.0
88.2
156.6
93.1
84.2
74.4
77.4
157.1
88.5
93.2
77.4
88.5
157.1
93.2
84.2
77.6
78.2
158.6
87.6
94.9
79.4
88.4
158.3
95.0
83.5
77.6
78.3
159.1
88.0
94.1
77.8
88.0
158.7
94.4
83.9
84.2
84.2
82.0
84.0
167.5
103.7
103.3
103.3
57.9
135.7
70.3
130.2
128.1
70.6
168.1
103.2
103.0
103.0
53.8
136.9
69.8
130.9
125.4
71.9
171.9
100.8
102.3
102.1
170.0
101.1
102.2
102.2
F(1) Xe(1) F(2)
3 3 3
3 3 3
F(1) Xe(1)-F(4)
3 3 3
F(1) Xe(1)-F(5)
3 3 3
F(1) Xe(1)-F(5A)
3 3 3
F(1) Xe(1)-F(6)
3 3 3
F(1) Xe(1)-F(7)
3 3 3
F(2) Xe(1)-F(4)
135.7
130.2
70.3
136.9
130.9
69.8
3 3 3
F(2) Xe(1)-F(5)
3 3 3
F(2) Xe(1)-F(5A)
3 3 3
F(2) Xe(1)-F(6)
70.6
71.9
3 3 3
F(2) Xe(1)-F(7)
128.1
77.6
77.6
78.5
78.5
155.1
87.5
87.5
87.5
87.5
125.4
77.8
77.8
79.4
79.4
155.6
87.8
87.8
87.8
87.8
3 3 3
F(4)-Xe(1)-F(5)
F(4)-Xe(1)-F(5A)
F(4)-Xe(1)-F(6)
F(4)-Xe(1)-F(7)
F(5)-Xe(1)-F(5A)
F(5)-Xe(1)-F(6)
F(5)-Xe(1)-F(7)
F(5A)-Xe(1)-F(6)
F(5A)-Xe(1)-F(7)
F(6)-Xe(1)-F(7)
Os(1)---F(3)---Os(1A)
83.1
83.1
83.1
83.1
166.2
89.2
89.2
89.2
89.2
166.2
83.5
83.5
83.5
83.5
167.0
89.3
89.3
89.3
89.3
167.0
79.3(1)
155.91(9)
87.67(5)
87.98(5)
87.67(5)
87.98(5)
159.0(1)
155.5(1)
114.94(6)
113.83(6)
157.0
150.9
113.8
113.8
158.9
155.4
115.6
115.6
143.0
140.7
Os(1)-F(1) Xe(1)
3 3 3
Os(1)-F(2) Xe(1)
3 3 3
a See Figure 1a for the atom labeling scheme. b See Figure 7a for the atom labeling scheme, where F(5A) and Os(1A) correspond to F5 and
Os0, respectively, for the symmetry-related atoms. c The SDDall(-PP) basis set was used augmented for F, O, and Xe with two d-type polarization
functions. d The Stuttgart basis set was used for Os with the f functional. The aug-cc-pVTZ(-PP) basis sets were used for all other atoms. e The aug-cc-
pVTZ(-PP) basis sets were used.
0
to a square-pyramidal geometry. The Xe2F11þ cation of
[Xe2F11][OsO3F3] (Figure 3) is comprised of two XeF5
cations bridged by a common fluoride ion such that the
trajectories of the fluorine bridge interactions with the
xenon atoms approach opposite the axial fluorine ligands
and from beneath the equatorial planes of the XeF5-
groups so that the axial lone pairs of the xenon atoms
are avoided. The four fluorine atoms that comprise the
þ

Article
Inorganic Chemistry, Vol. 49, No. 7, 2010 3505
Table 3. Experimental and Calculated Geometrical Parameters for [XeF5][OsO3F3] and [Xe2F11][OsO3F3]
[XeF5][OsO3F3]a
[Xe2F11][OsO3F3]b
calcd (Cs)
calcd (Cs)
exptl
SVWNc
B3LYPd
exptl
SVWNc
B3LYPd
˚
Bond Lengths (A)
Os-F(1)
Os-F(2)
Os-F(3)
Os-O(1)
Os-O(2)
Os-O(3)
2.011(2)
2.006(2)
2.028(2)
1.701(3)
1.701(3)
1.692(3)
2.514(2)
2.521(2)
2.468(2)
1.819(2)
1.866(2)
1.862(2)
1.866(2)
1.864(2)
2.032
2.032
1.999
1.711
1.711
1.711
2.373
2.373
2.420
1.890
1.923
1.924
1.924
1.923
2.052
2.052
1.990
1.688
1.688
1.689
2.460
2.460
2.606
1.879
1.911
1.912
1.912
1.911
2.004(2)
2.001(2)
2.018
2.033
2.072
1.949
1.703(2)
1.697(3)
1.711
1.710
1.689
1.690
Xe(1) F(1)
2.504(2)
2.800(2)
2.2953(9)
1.830(2)
1.859(2)
1.873(2)
1.873(2)
1.862(2)
3.353(2)
2.370
2.613
2.244
1.893
1.921
1.939
1.928
1.918
2.404
3.197
2.295
1.884
1.913
1.922
1.920
1.914
3 3 3
Xe(1) F(2)
Xe(1) F(3)e
3 3 3
3 3 3
Xe(1)-F(4)
Xe(1)-F(5)
Xe(1)-F(6)
Xe(1)-F(7)
Xe(1)-F(8)
Xe(1) O(1B)
3 3 3
Bond Angles (deg)
F(1)-Os-F(2)
74.4(1)
74.6(1)
159.4(1)
89.8(1)
89.3(1)
74.8(1)
88.8(1)
158.6(1)
90.8(1)
89.8(1)
87.3(1)
160.7(1)
103.0(2)
102.9(2)
103.6(2)
57.69(8)
58.87(8)
140.0(1)
71.6(1)
124.4(1)
128.3(1)
74.5(1)
58.84(8)
145.5(1)
129.0(1)
116.6(1)
71.8(1)
81.1(1)
150.6(1)
91.6(1)
71.95(9)
104.9(1)
129.5(1)
79.5(1)
79.5(1)
79.8(1)
79.2(1)
86.3(1)
158.9(1)
91.3(1)
86.3(1)
158.6(1)
88.3(1)
73.2
72.9
158.7
89.5
88.4
72.9
89.5
158.7
88.4
90.3
73.8
73.8
159.8
89.7
87.6
73.8
89.7
159.8
87.6
90.8
75.77(7)
78.96(9)
162.72(9)
88.5(1)
88.31(8)
75.77(7)
89.88(9)
159.5(1)
89.88(9)
88.31(8)
88.5(1)
73.9
76.3
160.2
88.5
88.6
73.9
89.7
157.5
89.7
88.6
76.0
77.8
163.8
84.8
88.7
76.0
92.2
155.1
92.2
88.7
F(1)-Os-F(3/1A)
F(1)-Os-O(1/1A)
F(1)-Os-O(2)
F(1)-Os-O(3/1)
F(2)-Os-F(3/1A)
F(2)-Os-O(1/1A)
F(2)-Os-O(2)
F(2)-Os-O(3/1)
F(3/1A)-Os-O(1/1A)
F(3/1A)-Os-O(2)
F(3/1A)-Os-O(3/1)
O(1/1A)-Os-O(2)
O(1/1A)-Os-O(3/1)
O(2)-Os-O(3/1)
90.3
90.8
88.5
84.8
156.5
104.0
103.9
103.9
61.4
156.7
103.7
103.4
103.4
60.0
162.72(9)
102.9(1)
101.4(1)
102.9(1)
54.90(6)
75.37(7)
139.68(7)
127.31(7)
74.43(7)
72.47(6)
125.60(7)
61.55(7)
135.39(8)
72.43(8)
67.94(6)
126.22(7)
132.84(7)
144.56(9)
79.08(9)
129.45(8)
118.10(9)
72.96(8)
79.43(9)
77.45(8)
79.10(9)
78.48(9)
88.24(9)
158.37(8)
88.1(1)
160.2
104.1
102.8
104.1
58.3
163.8
103.1
103.0
103.1
50.1
F(1) Xe(1) F(2)
3 3 3
3 3 3
3 3 3
3 3 3
F(1) Xe(1) F(3)e
60.0
57.2
72.4
71.6
F(1) Xe(1)-F(4)
147.4
111.7
130.1
84.6
71.5
60.0
147.4
71.5
84.6
130.1
111.7
137.2
128.2
71.8
148.3
112.0
128.3
84.5
72.4
57.2
148.3
72.4
84.5
128.3
112.0
139.3
126.8
72.4
140.3
128.5
75.6
70.7
123.1
62.4
135.1
70.3
69.1
128.1
131.1
145.9
82.2
130.8
112.2
71.8
80.1
78.0
80.4
78.6
89.9
142.6
124.3
75.3
73.4
123.5
59.1
138.0
74.3
66.8
122.3
132.5
145.6
78.3
125.9
117.8
74.1
80.3
79.0
80.4
79.2
86.8
3 3 3
F(1) Xe(1)-F(5)
3 3 3
F(1) Xe(1)-F(6)
3 3 3
F(1) Xe(1)-F(7)
3 3 3
F(1) Xe(1)-F(8)
3 3 3
F(2) Xe(1) F(3)e
3 3 3
3 3 3
F(2) Xe(1)-F(4)
3 3 3
F(2) Xe(1)-F(5)
3 3 3
F(2) Xe(1)-F(6)
3 3 3
F(2) Xe(1)-F(7)
3 3 3
F(2) Xe(1)-F(8)
3 3 3
F(3) Xe(1)-F(4)e
3 3 3
F(3) Xe(1)-F(5)e
3 3 3
F(3) Xe(1)-F(6)e
3 3 3
F(3) Xe(1)-F(7)e
71.8
72.4
3 3 3
F(3) Xe(1)-F(8)e
128.2
79.7
79.1
79.1
79.7
126.8
79.9
79.5
79.5
79.9
3 3 3
F(4)-Xe(1)-F(5)
F(4)-Xe(1)-F(6)
F(4)-Xe(1)-F(7)
F(4)-Xe(1)-F(8)
F(5)-Xe(1)-F(6)
F(5)-Xe(1)-F(7)
F(5)-Xe(1)-F(8)
F(6)-Xe(1)-F(7)
F(6)-Xe(1)-F(8)
F(7)-Xe(1)-F(8)
87.5
88.1
158.3
84.5
92.7
158.3
87.5
159.1
85.1
91.4
159.1
88.1
160.0
87.9
90.6
156.6
83.8
117.2
107.0
129.3
160.6
89.8
91.0
158.2
85.1
131.2
102.1
152.2
88.65(8)
155.91(8)
85.12(8)
119.39(7)
107.48(6)
135.9(1)
Os-F(1) Xe(1)
3 3 3
Os-F(2) Xe(1)
3 3 3
Xe(1)---F(3)---Xe(2)
a See Figure 2a for the atom labeling scheme. b See Figure 3a for the atom labeling scheme. c The SDDall(-PP) basis set, augmented for F, O, and Xe
with two d-type polarization functions, was used. d The Stuttgart basis set was used for Os with the f functional. The aug-cc-pVTZ(-PP) basis sets were
used for all other atoms. e The atom labeling scheme refers to the structure of [XeF5][OsO3F3]. In the case of [Xe2F11][OsO F ], the Xe(1) F(3) notation
should read as Xe(1)---F(3).
3 3 3
3
3

3506 Inorganic Chemistry, Vol. 49, No. 7, 2010
Hughes et al.
Figure 2. Depictions of (a) the structural unit in the X-ray crystal
structure of [XeF5][OsO3F3] with thermal ellipsoids drawn at the 70%
probability level, and (b) the primary and secondary coordination spheres
þ
of xenon in XeF5 showing the three secondary bonding interactions
between xenon and the three facial fluorine atoms of OsO3F3
-
.
F(1,2,3), of the anion (Figure 2b), forming a tripod
beneath the square base of the XeF5 cation, having
þ
very similar Xe F contact distances (2.514(2), 2.521(2),
3 3 3
˚
and 2.468(2) A, respectively). The shortest contact,
Xe(1) F(3), is likely a consequence of crystal packing
˚
3 3 3
Figure 1. Depictions of (a) the structural unit in the X-ray crystal
structure of [XeF5][μ-F(OsO3F2)2] with thermal ellipsoids drawn at the
70% probability level, and (b) the primary and secondary coordination
and is reflected in the longer Os-F(3) bond (2.028(2) A)
˚
and shorter Os-O(3) bond (1.692(3) A) that is trans to
spheres of xenon in XeF5þ showing the four secondary bonding interac-
˚
Os-F(3). The xenon atom is located 2.064 A above the
-
tions between xenon and the terminal fluorine atoms of μ-F(OsO3F2)2
.
F(1,2,3)-plane which is parallel, to withþin (5.2ꢀ, to the
equatorial F(5,6,7,8)-plane of the XeF5 cation. Eight-
coordinate xenon has also been observed in other XeF5
base of the square pyramid are coplanar within (0.245,
þ
˚
(0.004, and (0.021 A in [XeF5][μ-F(OsO3F2)], [XeF5]-
salts, for example, [XeF5]2[PdF6],23 [XeF5][AsF6],24 and
[OsO3F3], and [Xe2F11][OsO3F3], respectively, and the
respective apical fluorine atoms are located 1.460, 1.478,
[XeF5]2[NiF6].25 These examples also contain three long
Xe F cation-anion contacts that originate from within
3 3 3
the ion pair.
Nine coordination of the xenon atom of XeF5 in
˚
and 1.461 A above the equatorial plane and the xenon
˚
atoms lie 0.362, 0.341, and 0.369 A below that plane.
þ
The secondary bonding interactions that occur be-
tween the cations and anions in all three structures have
contact distances that are significantly less than the sum
of the xenon and fluorine van der Waals radii,20 resulting
in xenon atoms that are eight-coordinate in [XeF5][OsO3F3]
(Figure 2b) and nine-coordinate in [XeF5][μ-F(OsO3F2)]
(Figure 1b) and [Xe2F11][OsO3F3] (Figure 3b). The light
atom interatomic distances associated with the xenon
coordination spheres are similar, with the distances be-
tween the apical fluorine and four equatorial fluorine
atoms of the XeF5-groups being slightly shorter than the
[XeF5][μ-F(OsO3F2)] (Figure 1b) results from four short
contacts with the terminal fluorine atoms of the anion
(two from each OsO3F2-group) which again contact
xenon from beneath the square plane of the cation and
avoid the valence electron lone pair. The contact dis-
˚
tances are comparable (Xe F(1,1A) (2.622(1) A) and
3 3 3
Xe F(2,2A) (2.663(1) A)), with the xenon atom located
˚
3 3 3
1.909 A above the plane defined by the four contacting atoms
˚
of the anion, F(1,1A,2,2A). The four contacting fluorine
atoms are coplanar by symmetry and this plane isþparallel
((0.1ꢀ) to the equatorial F(5,5A,6,7)-plane of XeF5
.
average F F/O contact distances (Table S1, Supporting
3 3 3
The secondary contacts of the nine-coordinate xenon
atoms of [Xe2F11][OsO3F3] (Figure 3b) do not all origi-
nate from within the same ion pair. In the case of Xe(1),
two contacts are with terminal fluorine atoms, F(1) and
F(2), of the OsO3F3- anion, one is with the bridging F(3)
atom of the Xe2F11þ cation, and the remaining contact is
Information). All secondary cation-anion contacts are
between the fluorine atoms of the anion and the xenon
atoms, except in the case of [Xe2F11][OsO3F3] where an
oxygen atom of a neighboring OsO3F3- anion in the unit
cell provides an additional short contact to a xenon atom.
The anion contacts in all three salts occur from beneath
the equatorial planes of the XeF5-units so as to avoid
the valence electron lone pair position in the manner
described for [XeF5][RuF6].22
with O(1B) (3.353(2) A) of another OsO3F3- anion in the
˚
˚
unit cell. The Xe(1) F(2) contact distance (2.800(2) A)
3 3 3
þ
The three long contacts to the XeF5 cation in
[XeF5][OsO3F3] occur through the facial fluorine atoms,
(23) Leary, K.; Templeton, D. H.; Zalkin, A.; Bartlett, N. Inorg. Chem.
1973, 12, 1726–1730.
(24) Bartlett, N.; DeBoer, B. G.; Hollander, F. J.; Sladky, F. O.;
Templeton, D. H.; Zalkin, A. Inorg. Chem. 1974, 13, 780–785.
ꢂ
(22) Bartlett, N.; Gennis, M.; Gibler, D. D.; Morrell, B. K.; Zalkin, A.
(25) Jesih, A.; Lutar, K.; Leban, I.; Zemva, B. Eur. J. Solid State Inorg.
Inorg. Chem. 1973, 12, 1717–1721.
Chem. 1991, 28, 829–840.

Article
Inorganic Chemistry, Vol. 49, No. 7, 2010 3507
[XeF5][AsF6],24 [XeF5][PtF6],27 [XeF5][RuF6],22 [XeF5]-
[AgF4],28 [Xe2F11][AuF6],29 and [Xe2F11]2[NiF6].30 The
xenon coordination in [Xe2F11][OsO3F3] is similar to that
of the AuF6- salt where the secondary coordination sphere
of xenon also arises from one inter- and two intra-ion pair
contacts within the unit cell. The nine-coordination to
xenon in [XeF5][μ-F(OsO3F2)] is, however, unique because
þ
it is the only XeF5 salt known to have four secondary
fluorine contacts to a XeF5 cation that originate solely
þ
from the anion of its ion pair.
With the exception of Xe(1) F(2) in [Xe F ]-
3 3 3
[OsO F ] (2.800(2) A), the Xe F contact distances in
2
11
˚
3 3 3
all three salts are shorter than those in (OsO3F2)2
3
3
3
5
˚
2XeOF4 (2.757(5) A), which is accompanied by signifi-
cant charge transfer from the anion to the cation (see
Computational Results).
Raman Spectroscopy. The low-temperature Raman
spectra of [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and
[Xe2F11][OsO3F3] are shown in Figures 4-6, respectively.
The observed and calculated frequencies and mode de-
scriptions for [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3],
and [Xe2F11][OsO3F3] are provided in Tables 4-6, re-
spectively, where the atom numbering schemes are
given in Figure 7. Spectral assignments for [XeF5]-
[μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3]
were made by comparison with the calculated frequencies
and Raman intensities for the energy-minimized gas-
phase geometries of their ion pairs, which are in good
agreement with experiment at the SVWN and B3LYP
levels of theory.
Examination of Tables 4-6 reveals that several bands
in the Raman spectra of [XeF5][μ-F(OsO3F2)2], [XeF5]-
[OsO3F3], and [Xe2F11][OsO3F3] are split into two bands.
Factor-group analyses (see Tables S2-S4 and discussion
in the Supporting Information) were therefore under-
taken to account for these splittings, and are based on
analyses of the ion pairs in the crystal structures of these
salts. The Raman bands of [XeF5][μ-F(OsO3F2)2] and
[Xe2F11][OsO3F3] are predicted to be factor-group split
into two bands, but this splitting is only resolved for two
Raman bands of [Xe2F11][OsO3F3], namely, those occur-
ring at 933/936 and 422/426 cm-1. The Raman bands of
[XeF5][OsO3F3] are predicted to be factor-group split into
three bands, but splittings are only resolved for bands
occurring at 951/955, 946/948, 652/654, 615/617, and
386/390 cm-1, with the third component remaining un-
resolved.
Figure 3. Depictions of (a) the structural unit in the X-ray crystal
structure of [Xe2F11][OsO3F3] with thermal ellipsoids drawn at the 70%
probability level, and (b) the primary and secondary coordination spheres
þ
of xenon in the XeF5-units of Xe2F11 showing the secondary bonding
interactions between one oxygen atomþand three fluorine atoms of
OsO3F3- and one xenon atom of Xe2F11
.
is relatively long when compared with Xe(1) F(1)
˚
3 3 3
(2.504(2) A) because F(2) is equivalently coordinated to
both Xe(1) and Xe(1A), whereas F(1) forms a single short
˚
contact with Xe(1). The Xe(1) atom is located 1.916 A
above the near parallelogram-shaped arrangement of
F(1), F(2), F(3), O(1B) atoms, which are coplanar to
˚
within (0.0260 A and parallel to the F(5,6,7,8)-plane to
within (2.0ꢀ.
The planes of contacting atoms and the equatorial fluo-
rine atoms of the XeF5-groups in [XeF5][μ-F(OsO3F2)2]
(Figure 1b) and [Xe2F11][OsO3F3] (Figure 3b) have near-
staggered conformations. The xenon coordination spheres
may be described as distorted monocapped square anti-
prisms having dihedral angles between the basal fluorine
atom planes of the XeF5-groups and planes of contacting
atoms that are close to 45ꢀ (49.0ꢀ for the F(4,5,7)Xe(1)- and
F(1,3,4)Xe(1)-planes and 42.9ꢀ for the O(1B)F(2,4)Xe(1)-
and F(4,6,8)Xe(1)-planes of [Xe2F11][OsO3F3]; 41.4ꢀ for the
F(4,5,5A)Xe(1)- and F(1,2A,4)Xe(1)-planes and 48.6ꢀ for
the F(1A,2,4)Xe(1)- and F(4,6,7)Xe(1)-planes of [XeF5]-
[μ-F(OsO3F2)2]). The near-staggered arrangements provide
the closest packed arrangements for the fluorine atoms of
the equatorial XeF4-planes and the light atoms that com-
prise the secondary coordination sphere. In contrast, the
The mode descriptions provided in Tables 4-6 show
that the cation and anion modes are, for the most part,
weakly coupled within their respective ion pairs, with the
low-frequency deformation modes displaying the greatest
degree of coupling.
-
(a) OsO3F3 and μ-F(OsO3F2)2-. The vibrational
-
modes of OsO3F3 in [N(CH3)4][OsO3F3] have been
previously assigned under C3v symmetry, consistent with
a weakly ion-paired anion.4 The present assignments for
þ
equatorial XeF4-planes of Xe2F11 are eclipsed because
they are constrained by symmetry.
(27) Bartlett, N.; Einstein, F.; Stewart, D. F.; Trotter, J. J. Chem. Soc. A.
1967, 1190–1193.
þ
Nine-coordinate xenon occurs in other XeF5 and
3
ꢂ
Xe2F11 salts, for example, [XeF ][SbF ] XeOF ,26
þ
(28) Lutar, K.; Jesih, A.; Leban, I.; Zemva, B.; Bartlett, N. Inorg. Chem.
5
6
4
1989, 28, 3467–3471.
(29) Leary, K.; Zalkin, A.; Bartlett, N. Inorg. Chem. 1974, 13, 775–779.
ꢂ
(26) Pointner, B. E.; Suontamo, R. J.; Schrobilgen, G. J. Inorg. Chem.
2006, 45, 1517–1534.
(30) Jesih, A.; Lutar, K.; Leban, I.; Zemva, B. Inorg. Chem. 1989, 28,
2911–2914.

3508 Inorganic Chemistry, Vol. 49, No. 7, 2010
Hughes et al.
Figure 4. Raman spectrum of [XeF5][μ-F(OsO3F2)2] recorded at -150 ꢀC using 1064-nm excitation; the symbols denote FEP sample tube lines (*) and an
instrumental artifact (†).
Figure 5. Raman spectrum of [XeF5][OsO3F3] recorded at -150 ꢀC
using 1064-nm excitation; the symbols denote FEP sample tube lines (*)
Figure 6. Raman spectrum of [Xe2F11][OsO3F3] recorded at -150 ꢀC
using 1064-nm excitation; the symbols denote FEP sample tube lines (*),
and an instrumental artifact (†).
an instrumental artifact (†), and overlap of a [Xe2F11][OsO3F3] line with a
FEP sample tube line (§).
-
þ
þ
OsO3F3 in the XeF5 and Xe2F11 salts are in overall
good agreement with the previous assignments; however,
strong cation-anion fluorine bridge contacts result in
significant vibrational coupling between the anion and
the cation modes. These differences are the main focus of
the ensuing discussion.
X-ray Crystallography). As expected, the Os-O stretching
-
region of μ-F(OsO3F2)2 is more complex than that of
OsO3F3 because of vibrational coupling between the
-
-
two OsO3F3-units. The frequencies of μ-F(OsO3F2)2 are
in better agreement with those of their counterparts in
the neutral species (OsO3F2)¥ (934-957 cm-1),5,31,32
The Os-O stretching frequencies of [XeF5][μ-F(OsO3F2)2]
(933-957 cm-1), [XeF5][OsO3F3] (940-955 cm-1), and
[Xe2F11][OsO3F3] (933-945 cm-1) are shifted to higher
(OsO3F2)2 (937-955 cm-1),5 and (OsO F ) 2XeOF
3
3
2 2
4
(940-962 cm-1),5 than with those of OsO3F3- (Tables 5
and 6) owing to greater dispersion of negative charge in
-
frequencies when compared with those of the OsO3F3
anion in [M][OsO3F3] (M = N(CH3)4þ [908-920 cm-1];4
NOþ [920-934 cm-1];4 Csþ [915-932 cm-1];2 Rbþ [918-
928 cm-1];2 Kþ [916-932 cm-1];2 and Naþ [920-935
cm-1]2). The high-frequency shifts are in accordance with
the presence of several short cation-anion contacts that
withdraw negative charge from the anion, leading to more
covalent Os-O bonds than in the N(CH3)4þ, NOþ, and
the alkali metal salts. The Os-O stretching modes of
[XeF5][OsO3F3] are shifted to somewhat higher frequencies
than those of [Xe2F11][OsO3F3] because secondary bonding
interactions with the smaller XeF5þ cation areþstronger than
with the more weakly Lewis acidic Xe2F11 cation (see
-
μ-F(OsO3F2)2
.
The frequency ranges associated with the terminal
Os-F stretching modes of [XeF5][μ-F(OsO3F2)2]
(480-646 cm-1), [XeF5][OsO3F3] (447-585 cm-1), and
[Xe2F11][OsO3F3] (422-591 cm-1) salts are similar to the
Os-F stretching frequencies of the OsO3F3- anion in its
[M][OsO3F3] salts (M = N(CH3)4þ [504, 573 cm-1];4 NOþ
(31) Falconer, W. E.; Disalvo, F. J.; Griffiths, J. E.; Stevie, F. A.; Sunder,
W. A.; Vasile, M. J. J. Fluorine Chem. 1975, 6, 499–520.
(32) Beattie, I. R.; Blayden, H. E.; Crocombe, R. A.; Jones, P. J.; Ogden,
J. S. J. Raman Spectrosc. 1976, 4, 313–322.

Article
Inorganic Chemistry, Vol. 49, No. 7, 2010 3509
Table 4. Experimental Raman and Calculated Frequencies, Intensities, and Assignments for [XeF5][μ-F(OsO3F2)2]
a The Raman spectrum was recorded on a microcrystalline solid sample in a FEP tube at -150 ꢀC using 1064-nm excitation. Experimental Raman
intensities are given in parentheses and are relative intensities with the most intense band given as 100. The abbreviations denote shoulder (sh). b Values in
4
parentheses denote calculated Raman intensities (A u-1) and values in square brackets denote calculated infrared intensities (km mol-1). c SVWN/
˚
SDDall(-PP). d B3LYP/Stuttgart (Os) aug-cc-pVTZ(-PP) (Xe, O, F) e Assignments are for the energy-minimized geometry calculated at the SVWN level
of theory. See Figure 7a for the atom labeling scheme. The symbols denote stretch (ν), bend (δ), twist (Ft), rock (Fr), wag (Fw), and umbrella (δumb). The
abbreviation, def., denotes a deformation mode.
[555 cm-1];4 Csþ [482, 565 cm-1];2 Rbþ [490, 568 cm-1];2
Kþ [478, 490, 570 cm-1];2 Naþ [460, 490, 580 cm-1]2), and
occur at lower frequencies than those of the neutral
species, (OsO3F2)¥ [596, 610 cm-1] and (OsO3F2)2
[604 cm-1].5 The 646 ([XeF5][μ-F(OsO3F2)2]) and 591
([Xe2F11][OsO3F3]) cm-1 bands involve coupled terminal
Os-F and Xe-F stretches which result in shifts to higher
frequency when compared with the pure terminal Os-F
stretching frequencies of [XeF5][μ-F(OsO3F2)2] and
[Xe2F11][OsO3F3].
phase coupled with the axial Xe-F stretch which is
shifted to significantly higher frequency than the sym-
metric Os-F stretch of [XeF5][OsO3F3] (585 cm-1) and
[Xe2F11][OsO3F3] (591 cm-1). The in-phase terminal
Os-F stretch of [Xe2F11][OsO3F3] is weakly coupled to
all of the terminal Xe-F stretches of the Xe2F11þ cation
whereas the symmetric Os-F stretch of the OsF3 moiety
of [XeF5][OsO3F3] is not significantly coupled to any
other mode, and is in good agreement with the symme-
tric terminal Os-F stretching modes of [N(CH3)4]-
[OsO3F3] (573 cm-1),4 (OsO3F2)¥ (596 cm-1),5 and
(OsO3F2)2 (604 cm-1).5
The symmetric Os-F stretches of the terminal OsF2
groups of [XeF5][μ-F(OsO3F2)2] (646 cm-1) are in-

3510 Inorganic Chemistry, Vol. 49, No. 7, 2010
Hughes et al.
Table 5. Experimental Raman and Calculated Frequencies, Intensities, and Assignments for [XeF5][OsO3F3]
calcdb
exptla
SVWNc
B3LYPd
assgnts (Cs)e
955(12), 951(sh)
948(100), 946(sh)
940(39)
654(sh), 652(4)
670(32)
660(53)
617(11), 615(10)
599(44)
585(27)
457(5)
447(3)
411(3)
402(4)
390(14), 386(18)
380(12)
369(3)
986(22)[84]
983(55)[51]
985(27)[81]
625(8)[202]
624(11)[197]
622(58)[148]
572(16)[12]
556(13)[<0.1]
551(20)[149]
458(2)[7]
445(2)[7]
374(3)[4]
364(2)[25]
371(3)[4]
399(1)[195]
336(2)[6]
333(2)[7]
1008(23)[120]
1025(59)[53]
1006(20)[120]
621(8)[208]
620(7)[204]
619(86)[120]
569(22)[6]
551(16)[<0.1]
537(13)[171]
443(2)[12]
419(3)[7]
397(3)[3]
396(3)[3]
393(4)[5]
370(1)[181]
361(1)[7]
360(1)[19]
A00, ν(OsO1) - ν(OsO2)
A0, ν(OsO1) þ ν(OsO2) þ ν(OsO3)
A0, ν(OsO1) þ ν(OsO2) - ν(OsO3)
A00, [ν(XeF5) þ ν(XeF6)] - [ν(XeF7) þ ν(XeF8)]
A0, [ν(XeF5) þ ν(XeF8)] - [ν(XeF6) þ ν(XeF7)]
A0, ν(XeF4)
A0, ν(XeF4) - [ν(XeF5) þ ν(XeF6) þ ν(XeF7) þ ν(XeF8)]
A00, [ν(XeF5) þ ν(XeF7)] - [ν(XeF6) þ ν(XeF8)]
A0, ν(OsF1) þ ν(OsF2) þ ν(OsF3)
A0, [ν(OsF1) þ ν(OsF2)] - ν(OsF3)
A00, ν(OsF1) - ν(OsF2)
A00, Ft(O1OsO3) - δ(O2OsO3)
A0, δumb(OsO1O2O3)
A0, δ(O1OsO2)
A0, ν(Xe F ) þ ν(Xe F ) þ ν(Xe F )
3 3 3
3 3 3
3 3 3
1
2
3
A00, δ(F4XeF5F6) - Fw(F7XeF8)
A0, δ(F4XeF5F8) - Fw(F6XeF7)
A0, δumb(XeF5F6F7F8)
291(6)
299(3)
289(2)[31]
318(3)[61]
314(<1)[5]
277(<1)[6]
284(<1)[6]
309(2)[12]
234(2)[<1]
219(<0.1)[<0.1]
172(<1)[<1]
167(1)[1]
305(<1)[19]
292(<1)[30]
282(1)[1]
A00, Ft(O2OsO3) þ Ft(F1XeF2) þ Fr(F2XeF3)
A0, Fw(F1OsF2) - [δ(O3OsF3) þ Fw(O1OsO2)]
A00, Ft(F1OsF2) þ Fw(F1OsF3)
280(6)
213(1)
278(1)[2]
A0, δ(F1OsF2) þ δ(F3OsO3) þ ν(XeF3)
A0, δ(F5XeF8) þ δ(F6XeF7)
257(2)[<1]
231(<0.1)[<0.1]
191(<1)[<1]
183(<1)[<1]
163(<0.1)[<0.1]
133(1)[13]
112(<1)[<0.1]
103(<1)[1]
68(<0.1)[<1]
50(<0.1)[<1]
21(<0.1)[<0.1]
A00, Ft(F5XeF6) þ Ft(F7XeF8)
195(2)
146(2)
A00, δ(F5XeF6) - δ(F7XeF8)
A0, δ(F5XeF8) - δ(F6XeF7)
147(<0.1)[<0.1]
149(2)[4]
A00, Ftwist(OsO1O2O3) - Ftwist(OsF1F2F3)
130(1)
120(2)
A0, [XeF5][OsO3F3] breathing
112(<1)[<0.1]
102(<1)[<1]
88(<0.1)[<0.1]
89(<1)[<0.1]
7(<0.1)[<0.1]
A00, [XeF5][OsO3F3] def.
A0, Fw(F4XeF5F8) þ Fw(F6XeF7)
A00, Ft(O1OsO2) þ Ft(F1OsF2) þ Ft(O3OsF3)
A0, Fw(O1OsO2) þ Ft(O3OsF3) - Fw(F1OsF2)
A00, [XeF5][OsO3F3] def.
a The Raman spectrum was recorded on a microcrystalline solid sample in a FEP tube at -150 ꢀC using 1064-nm excitation. Experimental Raman
intensities are given in parentheses and are relative intensitieswith the most intense bandgiven as 100. The abbreviations denote shoulder(sh). Bands were
4
also observed at 536(6) and 639(7) cm-1 but were not assigned. b Values in parentheses denote calculated Raman intensities (A u-1) and values in square
˚
brackets denote calculated infrared intensities (km mol-1). c SVWN/SDDall(-PP). d B3LYP/Stuttgart (Os) aug-cc-pVTZ(-PP) (Xe, O, F). e Assignments
are for the energy-minimized geometry calculated at the B3LYP level of theory. See Figure 7b for the atom labeling scheme. The symbols denote stretch
(ν), bend (δ), twist (Ft), rock (Fr), wag (Fw), and umbrella (δumb). The abbreviation, def., denotes a deformation mode.
The asymmetric fluorine bridge stretching mode,
coupled to other vibrational modes. The ν(OsF1) -
ν(OsF2) stretching mode of [XeF5][OsO3F3] (447 cm-1
also is not coupled to any other mode and occurs at higher
-
ν(OsF3) - ν(Os0F3) (441 cm-1), of the μ-F(OsO3F2)2
)
anion is not significantly coupled to any other mode and
is comparable to the two asymmetric fluorine bridge
stretching modes of (OsO3F2)¥ (404, 413 cm-1).5 Upon
anion formation, a shift to lower frequency relative to
those of (OsO3F2)¥ would be expected for this mode;
however, this is not observed and can be attributed to
significant withdrawal of electron density from F1 and F2
by the XeF5þ cation which strengthens the Os---F bridge
bonds. In contrast, the symmetric ν(OsF3) þ ν(Os0F3)
0
0
frequency than the ν(OsF1) - ν(OsF1 ) þ Fr(O1OsO1 ) þ
δ(O2OsO1 ) mode of [Xe2F11][OsO3F3] (426/422 cm-1) as
0
a result of coupling with lower frequency OOsO and
FXeF bending modes.
(b) XeF5þ. Because vibrational assignments for the
XeF5þ cation under C4v symmetry have been previously
- 33-35
- 35
reported for other salts, e.g., AsF6
,
AuF6- 35
,
BF4
,
and are in good agreement with the present values for the
- 34,35 GaF4- 36 NiF62- 25 PdF62- 35 PtF6
,
,
,
,
- 35 RuF6
,
0
stretch is in-phase coupled to the Fw(F5 XeF5) þ
-
Fw(F6XeF7) bending mode (313 [SVWN] and 320
μ-F(OsO3F2)2 (C2v ion-pair symmetry, Table 4) and
OsO3F3 (Cs ion-pair symmetry, Table 5) salts, no
[B3LYP] cm-1) and is out-of-phase coupled to the
-
0
0
0
δ
umb(XeF1F2F1 F2 ) þ δ(F5XeF5 ) (337 [SVWN], 337
detailed discussion of their vibrational assignments is
provided. It is noteworthy that the bands at 280 and
380 cm-1 in the Raman spectrum of [XeF5][OsO3F3] are
[B3LYP] cm-1) bending mode ofXeF5þ. Only the in-phase
coupled mode was observed at 315 cm-1. The ν(OsF3) þ
ν(Os0F3) stretch is also in-phase coupled to the δ(O1OsO2)
þ δ(O1 Os0O2 ) mode of μ-F(OsO3F2)2- (342 cm-1). These
modes are shifted to lower frequencythanthepureν(OsF3)
- ν(Os0F3) mode as a consequence of coupling with lower
frequency OOsO deformation modes.
0
0
(33) Landa, B. Raman Spectroscopic Investigations of Some Fluoro-
xenon Compounds. Ph.D. Thesis, McMaster University, Hamilton, Ontario,
1974.
(34) Christe, K. O.; Curtis, E. C.; Wilson, R. D. in J. Inorg. Nucl. Chem.
Supplement 1976, 12, 159-165.
The asymmetric ν(OsF1) þ ν(OsF2) - ν(OsF3) modes
of [XeF5][OsO3F3] (457 cm-1) and [Xe2F11][OsO3F3] (448
cm-1) have similar frequencies and are not significantly
(35) Adams, C. J.; Bartlett, N. Isr. J. Chem. 1978, 17, 114–125.
ꢂ
ꢀ
(36) Zemva, B.; Milicev, S.; Slivnik, J. J. Fluorine Chem. 1978, 11, 519–
526.

Article
Inorganic Chemistry, Vol. 49, No. 7, 2010 3511
Table 6. Experimental Raman and Calculated Frequencies, Intensities, and Assignments for [Xe2F11][OsO3F3]
a The Raman spectrum was recorded on a microcrystalline sample in a FEP sample tube at -150 ꢀC using 1064-nm excitation. Experimental Raman
intensities are given in parentheses and are relative intensities with the most intense band given as 100. The abbreviations denote shoulder (sh). A band
b
4
was also observed at 523(6)cm-1 but was not assigned. Values in parentheses denote calculated Raman intensities (A u-1) and values in square brackets
denote calculated infrared intensities (km mol-1). c SVWN/SDDall(-PP). d B3LYP/Stuttgart (Os) aug-cc-pVTZ(-PP) (Xe, O, F). e Assignments are for
the energy-minimized geometry calculated at the B3LYP level of theory. See Figure 7c for the atom labeling scheme. The symbols denote stretch (ν), bend
(δ), twist (Ft), rock (Fr), wag (Fw), umbrella (δumb), and F5, F6, F7, F8 (F4e). The abbreviation, def., denotes a deformation mode. f The band overlaps with
a FEP sample tube band; the intensity is not corrected.
˚
associated with the secondary bonding interactions be-
tween the cation and the anion, and are assigned to the
and VF6-38 salts. The present assignments provide a morþe
detailed description of the vibrational modes of Xe2F11
under Cs symmetry (Table 6).
coupled δ(F OsF ) þ δ(F OsO ) þ ν(Xe F ) and the
3 3 3
1
2
3
3
3
þ
ν(Xe F ) þ ν(Xe F ) þ ν(Xe F ) modes, respec-
Among the most noteworthy features of the Xe2F11
3 3 3
3 3 3
3 3 3
1
2
3
tively.
Raman spectrum of [Xe2F11][OsO3F3] are the Xe-F
stretching frequencies which occur between 580 anþd
656 cm-1, and are comparable with other Xe2F11
salts. The band at 591 cm-1 is assigned to extensively
þ
(c) Xe2F11þ. The vibrational modes of Xe2F11 have
not been assigned in detail in prior vibrational studies,
e.g., the AsF6 , , , , ,
- 35 PF6- 35 PbF62- 37 PdF62- 37 SnF6
- 37
ꢂ
ꢂ
(37) Zemva, B.; Jesih, A. J. Fluorine Chem. 1984, 24, 281–289.
(38) Jesih, A.; Zemva, B.; Slivnik, J. J. Fluorine Chem. 1982, 19, 221–226.

3512 Inorganic Chemistry, Vol. 49, No. 7, 2010
Hughes et al.
coupled Xe-F and Os-F stretches involving the three
facial Os-F bond stretches and the 10 primary Xe-F
bond stretches of the XeF5-units (Table 6). The most
intense Xe-F stretching band at 656 cm-1 is assigne0d to
0
the [ν(Xe1F4) þ ν(Xe1F5) þ ν(Xe1F6)] þ [ν(Xe1 F4 ) þ
0
0
0
0
ν(Xe1 F5 ) þ ν(Xe1 F6 )] stretching mode and is in good
agreement with the most intense cation band of other
Xe2F11þ salts, e.g., AsF6- (663cm-1),35 PF6- (666cm-1),35
2-
2-
2-
PbF6 (650 cm-1),37 PdF6 (651 cm-1),37 SnF6 (657
cm-1),37 and VF6 (655 cm-1).38 The Xe1---F3---Xe1
-
0
bridge stretches are predicted to be weak and to occur
at 370, 335, and 300 (SVWN) and 329, 322, and 276
(B3LYP) cm-1, but could not be obser0ved. In the present
case, the symmetric ν(Xe1F3) þ ν(Xe1 F3) bridge stretch
0
0
)
is in-phase coupled to the δumb(XeF4e) þ δumb(Xe1 F4e
bending mode, whereas the asymmetric ν(Xe1F3) -
0
ν(Xe1 F3) bridge stretch is in-phase coupled to both
0
0
the Ft(F1OsF1 ) þ Fw(F2OsO2) and the Ft(O1OsO1 ) -
0
Ft(F1OsF1 ) bending modes. The three modes are pre-
dicted to occur between 300 and 370 (SVWN) and
276-329 (B3LYP) cm-1
.
Computational Results. The structures of [XeF5]-
[μ-F(OsO3F2)2] (C2v), [XeF5][OsO3F3] (Cs), [Xe2F11]-
[OsO3F3] (Cs), XeF5þ (C4v), Xe2F11þ (Cs), OsO3F3- (C3v),
and μ-F(OsO3F2)2- (C2) (Figure 7 and Figures S5 and S6
in the Supporting Information) were optimized using
SVWN and B3LYP methods under the specified symme-
tries and resulted in stationary points with all frequencies
real. The geometrical parameters and vibrational fre-
quencies were benchmarked, as previously described,
using cis-OsO2F4 and XeOF4.5
Figure 7. Calculated gas-phase geometries at the B3LYP level of theory
for (a) [XeF5][μ-F(OsO3F2)2] (C2v), (b) [XeF5][OsO3F3] (Cs), and (c)
[Xe2F11][OsO3F3] (Cs).
inter-ion pair contact (vide supra) and consequently does
not reproduce the experimental ion-pair geometry as
well. The tri-coordination of F(2) is reproduced, but the
Xe1 F and Xe
F contact distances at the B3LYP
2
(a) Calculated Geometries. The calculated ion-pair
geometries of [XeF5][μ-F(OsO3F2)2] (Table 2), [XeF5]-
[OsO3F3], and [Xe2F11][OsO3F3] (Table 3) are in good
agreement with the experimental geometries, with slightly
better agreement for the Xe-F bond lengths at the
B3LYP level, and for the Os-F and Os-O bond lengths
of the [XeF5][OsO3F3] and [Xe2F11][OsO3F3] salts at the
SVWN level. The calculations confirm that the gas-
phase ion pairs are stable entities, and all trends in their
crystal structures are reproduced by the calculated
ion-pair geometries, with the largest discrepancies occur-
3 3 3
level (3.197 and 3.197 A) are significantly longer than
3 3 3
2
2
˚
˚
the SVWN (2.613 and 2.613 A) and the experimental
˚
(2.800(2) A) values.
The geometries of the isolated gas-phase cations and
anions have also been calculated to assess the effects of
ion pairing on the primary bond lengths and angles. The
fluorine atoms of the ion-paired OsO3F3- anions strongly
coordinate to xenon, elongating the Os-F bonds (av.
˚
2.022, SVWN; 2.031, B3LYP A) when compared with
those of the gas-phase OsO3F3 anion (1.950, SVWN;
˚
1.961, B3LYP A) (Table S5, Supporting Information).
-
ring for the Xe F contact distances. In all cases, the
3 3 3
As a result, the Os-O bond lengths of the ion pair are
significantly shorter (av. 1.711, SVWN; 1.689, B3LYP A)
SVWN calculations predict slightly shorter secondary
bonding interactions than the B3LYP calculations
(Tables 2 and 3).
˚
than those of the free anion (1.737, SVWN; 1.711, B3LYP
˚
-
A). The same trends are observed for μ-F(OsO3F2)2
The calculated geometries of the [XeF5][μ-F(OsO3F2)2]
and [XeF5][OsO3F3] ion pairs are in better agreement with
their experimental geometries than [Xe2F11][OsO3F3],
underscoring that both ion pairs are well isolated in their
crystal structures, showing no inter-ion pair contacts. The
experimental Os---F3---Os0 bridge bond lengths of
(Table 2), that is, the Os-O bond lengths are shortened
and the Os-F1,2 bond lengths are elongated upon co-
ordination to XeF5þ. The Os---F---Os bond angle of the
free μ-F(OsO3F2)2- anion is more closed (143.0ꢀ, SVWN;
140.7ꢀ, B3LYP) relative to that of the gas-phase ion pair
(150.9ꢀ, SVWN; 155.4ꢀ, B3LYP) because chelation of the
˚
[XeF5][μ-F(OsO3F2)2] (2.1179(5) A) are particularly well
þ
˚
modeled by both the B3LYP (2.147 A) and SVWN (2.115
XeF5 cation through xenon contacts with the fluorine
0
˚
ligands of the anion results in compression of this angle.
In conþtrast, the Xe---F---Xe bond angle of the free
Xe2F11 cation is more open (141.8ꢀ, SVWN; 171.2ꢀ,
B3LYP) than in [Xe2F11][OsO3F3] (129.3ꢀ, SVWN;
152.2ꢀ, B3LYP), which is again attributed to coordina-
tion of the anion fluorine ligands to xenon, leading to
compression of the Xe---F---Xe angle in the chelate
A) structures. The Os---F3---Os bridge bond angle
(155.5(1)o) is also very well reproduced at the B3LYP
(155.4ꢀ) and SVWN (150.9ꢀ) levels. For this structure, the
Xe F contact distances calculated at the B3LYP (2.643
3 3 3
˚
and 2.644 A) level better reproduce the experimental
˚
values (2.622(1) and 2.663(1) A) than those calculated
˚
at the SVWN level (2.461 and 2.461 A).
þ
relative to that of the free Xeþ2F11 cation. The Xe-F
The calculated structure of the [Xe2F11][OsO3F3] ion
pair does not take into account the additional Xe
þ
bond lengths of the free XeF5 (Table 2) and Xe2F11
O
3 3 3

Article
Inorganic Chemistry, Vol. 49, No. 7, 2010 3513
(Table S6, Supporting Information) cations are slightly
shorter than in their respective ion pairs as a consequence
of the extra electron density donated to the xenon cation
by the anion, resulting in longer, more polar primary
Xe-F bonds in the ion pairs (see below for anion-cation
charge drift values).
(b) Charges, Valencies, and Bond Orders. The Natural
Bond Orbital (NBO)39-42 analyses were carried out for
the optimized B3LYP [SVWN] gas-phase geometries of
[XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], [Xe2F11][OsO3F3]
bond orders compensate for the negative charge drift
onto the cation via the secondary bonding interactions.
The calculated negative charge drifts from anion to
cation within the ion pair reflect this trend: [XeF5]-
[μ-F(OsO3F2)2], 0.19 [0.37]; [XeF5][OsO3F3], 0.25 [0.39];
[Xe2F11][OsO3F3], 0.23 [0.37].
Other than the Xe---F3 bridge bond orders of Xe2F11
3 3 3
for the F2 atom of [Xe2F11][OsO3F3] to 0.12 [0.16] for the
þ
,
the secondary Xe F bond orders range from 0.02 [0.10]
F and F atoms of [XeF ][OsO F ]. The lower Xe
F
2
3 3 3
bond order results from the interaction of F2 with both
1
3
5
3
3
þ
(Table S7, Supporting Information), XeF5þ, Xe2F11
(Table S8, Supporting Information), OsO3F3-, and
μ-F(OsO3F2)2- (Table S9, Supporting Information).
The NPA (Natural Population Analysis) gave positive
charges of 2.19 [1.88], 2.17 [1.87], and 2.18 [1.87] for
osmium and 3.29 [3.05], 3.28 [3.04], and 3.29 [3.06] for
xenon in the [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and
[Xe2F11][OsO3F3] ion pairs, respectively. The negative
charges of the light atoms indicate that the bonding in
the ion pairs is polar covalent. The average charges of the
oxygen ligands are less negative than the average charges
of the fluorine ligands in both the anions and the cations,
which is consistent with significant charge transfer from
the filled oxygen p orbitals into the empty d orbitals of
osmium. Overall, the fluorine ligands of the anions are
more negative than those of the cations, which is consis-
tent with the net charges of the cation and anion.
xenon atoms of the Xe2F11þ cation. The higher Xe
bond orders of [XeF5][OsO3F3] when compared with the
F
1,3
3 3 3
Xe 1,2 bond orders of [XeF5][μ-F(OsO3F2)2] correlate
F
3 3 3
with the higher positive charge on xenon that results from
only eight primary and secondary contacts to xenon
instead of nine as in the remaining two ion pairs (see
Calculated Geometries).
þ
The axial and equatorial Xe-F bond orders of XeF5
and Xe2F11þ are only slightly altered upon coordination
of either cation to OsO3F3-. The equatorial Xe-F bond
orders for all three ion pairs are similar (0.47-0.48
[0.41-0.44]) and are only slightly less than those of free
XeF5þ and Xe2F11þ (0.48-0.49 [0.48]). The axial Xe-F
bonds of the ion pairs have significantly higher bond
orders (0.50 [0.45-0.46]) than the equatorial Xe-F
bonds. The axial Xe-F bond orders of the ion pairs
are similar to those of the free cations calculated at the
B3LYP level (0.51-0.53), but at the SVWN level they are
somewhat higher for the free cations (0.50-0.52). The
lower Xe-F bond orders for all of the ion pairs relative to
The Xe---F3 bridge bond orders of [Xe2F11][OsO3F3]
(0.18 [0.20]) and the Os---F3 bond orders of [XeF5]-
[μ-F(OsO3F2)2] (0.21 [0.25]) are significantly less than
those of the terminal Xe-F (av. 0.46-0.50 [0.41-0.46])
and Os-F (av. 0.29-0.38 [0.32-0.37]) bonds of either
salt because the bridging fluorine atoms are equally
shared between the two electropositive heavy atoms.
Although the Xe---F3 and Os---F3 bridge bond orders
are simiþlar, the average terminal Xe-F bond orders
þ
þ
those of free XeF5 and Xe2F11 are in accord with the
calculated anion-cation charge drifts (vide supra).
Conclusions
þ
of XeF5 and Xe2F11 are more than double the bridg-
The [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11]-
[OsO3F3] salts have been synthesized by the reactions of
stoichiometric mixtures of XeF6 and (OsO3F2)¥. All three
salts are room-temperature stable but dissociate back to the
starting materials after prolonged heating at 50 ꢀC. The salts
provide the only examples of noble-gas cations that are
stabilized by metal oxide fluoride anions and the first exam-
ple of a salt of the fluorine-bridged μ-F(OsO3F2)2- anion. All
three salts exist as discrete ion pairs in which the fluorine
ligands of the osmium oxide fluoride anions mainly interact
by means of secondary bonding interactions with the xenon
atoms of the cations. Ion-pairing results in nine-coordination
at the xenon atoms of [XeF5][μ-F(OsO3F2)2] and [Xe2F11]-
[OsO3F3] and eight-coordination at the xenon atom of
[XeF5][OsO3F3]. The primary coordination spheres of the
osmium atoms of μ-F(OsO3F2)2- and OsO3F3- are pseudo-
octahedral with facial arrangements of oxygen and fluorine
ing Xe---F3 bond order in Xe2F11þ. In contrast, the
-
average terminal Os-F bond orders of OsO3F3 and
-
μ-F(OsO3F2)2 are less than twice the Os---F3 bridge
bond order. The difference is attributable to significantly
higher positive charges on the xenon atoms than on the
osmium atoms (Table S7, Supporting Information),
which result in lower negative charges on the fluorine
atoms of the xenon cations and more covalent Xe-F
bonds than for fluorine bonded to osmium.
The Os-O bond orders of both ion pairs are similar
(0.87-0.88 [0.86-0.86]) but slightly greater than those of
the free anions (0.85-86 [0.81-0.83]). The Os-F bond
orders (0.29-0.38 [0.32-0.37]) are also similar but less
than those of the free anions (0.38-0.41 [0.39-0.42]).
Both features result from significant fluorine bridge
interactions between the fluorine ligands of osmium and
xenon atoms of the ion pairs. The somewhat higher Os-O
-
ligands. The OsO3F3 anions have geometrical parameters
that are closer to those of neutral trioxo Os(VIII) species,
þ
þ
indicating that the XeF5 and Xe2F11 cations withdraw
significant electron density from the anion by means of their
secondary bonding interactions. Quantum-chemical calcula-
tions have been used to model the ion pairs and their
component ions and provide energy-minimized geometries
that are in very good agreement with the experimental
structures. The Raman spectra of all three salts have been
fully assigned based on the calculated vibrational modes.
(39) Reed, A. E.; Weinstock, R. B.; Weinhold, F. J. Chem. Phys. 1985, 83,
735–746.
(40) Glendening, E. D.; Reed, A. E.; Carpenter, J. E.; Weinhold, F. NBO,
Version 3.1; Gaussian Inc.: Pittsburgh, PA, 1990.
(41) Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. Rev. 1998, 88, 899–
926.
(42) Glendening, E. D.; Badenhoop, J. K.; Reed, A. E.; Carpenter, J. E.;
Bohmann, C. M.; Morales, C. M.; Weinhold, F. NBO, Version 5.0; Theore-
tical Chemical Institute, University of Wisconsin: Madison, WI, 2001.

3514 Inorganic Chemistry, Vol. 49, No. 7, 2010
Hughes et al.
Experimental Section
Raman Spectroscopy. The low-temperature Raman spectra of
[XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3],
(-150 ꢀC) were recorded on a Bruker RFS 100 FT Raman
spectrometer using 1064-nm excitation and a resolution of
1 cm-1 as previously described.4 The spectra were recorded
using a laser power of 300 mW and a total of 1500, 900, and 1200
scans, respectively.
Apparatus and Materials. Manipulations involving air-sensi-
tive materials were carried out under anhydrous conditions as
previously described.43 All preparative work was carried out
1
=
in FEP reaction vessels fabricated from 4-in. o.d. lengths of
tubing, unless otherwise noted, that had been heat-sealed at one
end and connected by means of 45ꢀ SAE flares and compression
fittings to Kel-F valves. Reaction vessels were dried on a Pyrex
glass vacuum line and then transferred to a metal vacuum line
where they were passivated with F2 for several hours, refilled
with dry N2, and placed in a drybox until used. All vacuum line
X-ray Crystallography. (a) Crystal Growing. Details of
crystal growing are provided in the Supporting Information.
Crystals of [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and
[Xe2F11][OsO3F3] having the dimensions 0.39 ꢁ 0.10 ꢁ 0.10,
0.21 ꢁ 0.21 ꢁ 0.20, and 0.39 ꢁ 0.11 ꢁ 0.07 mm3, respectively,
were selected at -105 (3 ꢀC for low-temperature X-ray struc-
ture determination and were mounted in a cold stream
(-173 ꢀC) on a goniometer head as previously described.4
(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 area detector and a
triple-axis goniometer, controlled by the APEX2 Graphical User
Interface (GUI) software,47 and a sealed source emitting graphite-
1
=
connections were made by use of 4-in. 316 stainless steel
Swagelok Ultratorr unions fitted with Viton O-rings. Osmium
trioxide difluoride, (OsO3F2)¥, was synthesized by reaction of
OsO4 (Koch-Light, 99.9%) with ClF3.12 Xenon hexafluoride,
XeF6, was synthesized by reaction of xenon gas with elemental
fluorine,44 and XeOF4 was synthesized by hydrolysis of XeF6.45
Commercial anhydrous HF (Harshaw Chemicals Co.) was
further dried by treatment with elemental fluorine using the
standard literature procedure.46
˚
monochromated Mo-KR radiation (λ = 0.71073 A). Diffraction
Synthesis of [XeF5][μ-F(OsO3F2)2]. On a metal vacuum line,
0.0296 g (0.121 mmol) of XeF6 was sublimed into a 1=4-in. o.d.
FEP weighing vessel. Inside the drybox, a 4-mm FEP reaction
tube was loaded with 0.0496 g (0.180 mmol) of orange
(OsO3F2)¥. The reaction vessel and weighing vessel were then
transferred to a metal vacuum line, and XeF6 (0.0228 g, 0.0930
mmol) was sublimed from the weighing vessel into the reaction
vessel containing (OsO3F2)¥ under static vacuum at -196 ꢀC.
Warming the reaction mixture to room temperature (25 ꢀC)
initially resulted in a deep orange liquid and unreacted
(OsO3F2)¥. The sample solidified, as (OsO3F2)¥ was consumed,
to form orange crystalline [XeF5][μ-F(OsO3F2)2]. Heating the
sample at 50 ꢀC for 1 h under 1 atm of dry N2 to ensure complete
reaction did not result in any physical changes.
data collection at -173 ꢀC consisted of a full φ-rotation at a fixed
χ = 54.74ꢀ with 0.36ꢀ (1010) frames, followed by a series of short
(250 frames) ω scans at various φ settings to fill the gaps. The
crystal-to-detector distances were 4.976, 4.954, and 4.969 cm for
[XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3],
respectively, and the data collections were carried out in a 512 ꢁ
512 pixel mode using 2 ꢁ 2 pixel binning. Processing of the raw
data sets were completed by using the APEX2 GUI software,47
which applied Lorentz and polarization corrections to three-dimen-
sionally integrated diffraction spots. The program SADABS,48 was
used for the scaling of diffraction data, the application of decay
corrections, and empirical absorption corrections on the basis of the
intensity ratios of redundant reflections.
(c) Solution and Refinement of the Structures. The XPREP49
program was used to confirm the unit cell dimensions and the
crystal lattices. The solution was obtained by direct methods
which located the positions of the atoms defining [XeF5]-
[μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3]. The
final refinement was obtained by introducing anisotropic ther-
mal parameters and the recommended weightings for all of the
atoms. The maximum electron densities in the final difference
Fourier maps were located near the heavy atoms. All calcula-
tions were performed using the SHELXTL-plus package49 for
the structure determinations and solution refinements and for
the molecular graphics. The choices of space group for [XeF5]-
[μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11][OsO3F3] were
confirmed by Platon from the WinGX software package.50
Synthesis of [XeF5][OsO3F3]. Following a synthetic procedure
similar to that outlined for [XeF5][μ-F(OsO3F2)2], 0.0772 g
(0.315 mmol) of XeF6 was initially sublimed into a FEP weigh-
ing vessel and 0.0675 g (0.244 mmol) of (OsO3F2)¥ was loaded
into a FEP reaction vessel. Xenon hexafluoride (0.0614 g,
0.250 mmol) was sublimed from the weighing vessel into the
reaction vessel containing (OsO3F2)¥. Upon warming to room
temperature (25 ꢀC), a deep orange liquid formed. The sample
was heated at 50 ꢀC for 1 h under 1 atm of dry N2 to ensure
complete reaction, and upon cooling to 0 ꢀC, an orange crystal-
line solid formed.
Synthesis of [Xe2F11][OsO3F3]. Following a synthetic proce-
dure similar to that outlined for [XeF5][μ-F(OsO3F2)2], 0.1255 g
(0.512 mmol) of XeF6 was initially sublimed into a FEP weigh-
ing vessel and 0.0601 g (0.218 mmol) of orange (OsO3F2)¥ was
loaded into a FEP reaction vessel. Xenon hexafluoride, 0.1224 g
(0.499 mmol) was sublimed from the weighing vessel into the
reaction vessel containing (OsO3F2)¥. Upon warming the reac-
tion mixture to room temperature (25 ꢀC), a light orange
crystalline solid formed. The sample was then warmed to
50 ꢀC under 1 atm of dry N2, whereupon the sample melted,
forming a deep orange liquid which solidified upon cooling to
room temperature.
Computational Methods
The optimized geometries and frequencies of the ion pairs
[XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], [Xe2F11][OsO3F3]
-
and of theions XeF5þ,Xe2F11þ,OsO3F3-,andμ-F(OsO3F2)2
were calculated at the SVWN and B3LYP51 levels of theory.
The Stuttgart semi-relativistic large core and effective core
pseudopotential basis sets (SDDall) augmented for F, O, and
Xe with two d-type polarization functions by Huzinaga52 were
Note: prolonged heating (>2 h) of all three salts to 50 ꢀC
under 1 atm of nitrogen led to sublimation of XeF6 out of the
heated zone and condensation on the cooler walls of the reaction
vessel.
(47) APEX2, Release 2.0-2; Bruker AXS Inc.: Madison, WI, 2005.
(48) Sheldrick, G. M. SADABS (Siemens Area Detector Absorption
Corrections), version 2.10; Siemens Analytical X-ray Instruments Inc.: Madison,
WI, 2004.
(49) Sheldrick, G. M. SHELXTL-Plus, release 6.14; Siemens Analytical
X-ray Instruments, Inc.: Madison, WI, 2000-2003.
(43) Casteel, W. J.; Dixon, D. A.; Mercier, H. P. A.; Schrobilgen, G. J.
Inorg. Chem. 1996, 35, 4310–4322.
(44) Chernick, C. L.; Malm, J. G. Inorg. Synth. 1966, 8, 259–260.
(45) Schumacher, G. A.; Schrobilgen, G. J. Inorg. Chem. 1984, 23, 2923–
2929.
(46) Emara, A. A. A.; Schrobilgen, G. J. Inorg. Chem. 1992, 31, 1323–
1332.
(50) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837–838.
(51) Frisch, M. J. et. Gaussian 03, Revision B.04; Gaussian, Inc.: Pittsburgh,
PA, 2003.
(52) Huzinaga, S.; Andzelm, J.; Kolobukowski, M.; Radzio-Andzelm, E.;
Sakai, Y.; Tatewaki, H. Gaussian Basis Sets for Molecular Calculations;
Physical Science Data 16; Elsevier: Amsterdam, The Netherlands, 1984.

Article
Inorganic Chemistry, Vol. 49, No. 7, 2010 3515
used at the SVWN level, and the Stuttgart basis set augmented
by one f-type polarization function (Rf Os 0.886)53 for osmium
and aug-cc-pVTZ basis sets for xenon, oxygen, and fluorine
were used at the B3LYP level.
Academic Research Computing Network. (SHARCNET: www.
Sharcnet.ca.)
Supporting Information Available: Comprehensive lists of
known XeF5þ and Xe2F11þ salts and their references; discussion
of the crystal packing in [XeF5][μ-F(OsO3F2)2], [XeF5]-
[OsO3F3], and [Xe2F11][OsO3F3]; view of the crystallographic
unit cell along the c-axis for [XeF5][μ-F(OsO3F2)2] (Figure S1),
[XeF5][OsO3F3] (Figure S2), and [Xe2F11][OsO3F3] (Figure S3);
the primary coordination sphere formed by the light atoms of
the OsO3F3-unit (Figure S4); interatomic distances between the
light atoms forming the coordination spheres of the Xe and Os
atoms in [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11]-
[OsO3F3] (Table S1); factor-group analyses for [XeF5]-
[μ-F(OsO3F2)2] (Table S2), [XeF5][OsO3F3] (Table S3), and
[Xe2F11][OsO3F3] (Table S4); discussion of factor-group ana-
lyses for [XeF5][μ-F(OsO3F2)2], [Xe2F11][OsO3F3], and
[Xe2F11][OsO3F3]; calculated B3LYP gas-phase geometries
Pseudopotentials were used with the appropriate basis sets
forbothosmium(SDDall-PP)andxenon(aug-cc-pVTZ-PP).
The combined use of SDDall and SDDall-PP or aug-
cc-pVTZ and aug-cc-pVTZ-PP basis sets are indicated as
SDDall(-PP) or aug-cc-pVTZ(-PP). Quantum-chemical cal-
culations were carried out using the program Gaussian 03.51
The levels and basis sets were benchmarked by calculating
cis-OsO2F4 and XeOF4 as previously described.5 The geome-
tries were fully optimized using analytical gradient methods.
After optimization at one level of theory, the geometries were
calculated at the other level of theory to ensure an equivalent
energy-minimized geometry had been achieved. The vibra-
tional frequencies were calculated at the SVWN and B3LYP
levels using the appropriate minimized structure, and the
vibrational mode descriptions were arrived at with the aid
of Gaussview.54
þ
þ
-
for XeF5 and Xe2F11 (Figure S5) and for OsO3F3 and
μ-F(OsO3F2-)- (Figure S6); calculated geometrical parameters
þ
for OsO3F3 (C3v) (Table S5) and Xe2F11 (Cs) (Table S6);
natural bond orbital (NBO) valencies, bond orders and
NPA charges for [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and
[Xe2F11][OsO3F3] (Table S7), forXeF5þ andXe2F11þ (Table S8),
and for OsO3F3 and μ-F(OsO3F2)2 (Table S9); details of
crystal growing for [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3],
and [Xe2F11][OsO3F3]; complete reference 51; The X-ray crys-
tallographic files in CIF format for the structure determina-
tion of [XeF5][μ-F(OsO3F2)2], [XeF5][OsO3F3], and [Xe2F11]-
[OsO3F3]. This material is available free of charge via the
Internet at http://pubs.acs.org.
Acknowledgment. We thank the Natural Sciences and En-
gineering Research Council of Canada for the award of post-
graduate scholarships (M.J.H.) and for support in the form of a
Discovery Grant (G.J.S.). The computations were conducted
with the aid of the facilities of the Shared Hierarchical
-
-
(53) Ehlers, A. W.; Bohme, M.; Dapprich, S.; Gobbi, A.; Hollwarth, A.;
Jonas, V.; Kohler, K. F.; Stegmann, R.; Veldkamp, A.; Frenking, G. Chem.
Phys. Lett. 1993, 208, 111–114.
(54) GaussView, release 3.0; Gaussian Inc.: Pittsburgh, PA, 2003.