One dimensional group 12 metal undecafluoridoditantalates

Article abstract of DOI:10.1016/j.jfluchem.2016.07.019

The reactions between group 12 metals and the acidic TaF₅were studied in the anhydrous HF (aHF) solvent. We were able to prepare and characterize the first compounds containing metal M²⁺cations and undecafluoridodimetallate anions – M(Ta₂F₁₁)₂(M?=?Cd, Hg) without the additional cations, anions or ligands included in the crystal structure. They both crystallize in P-1 space group with cell parameters a?=?9.1571(4)??, b?=?9.8750(3)??, c?=?10.9400(7) ?, α?=?94.389(4)°, β?=?113.124(5)°, γ?=?101.142(3)°, V?=?879.81(8) ?³, Z?=?2, T?=?150?K (Cd(Ta₂F₁₁)₂) and a?=?9.1381(5)??, b?=?9.8613(6)??, c?=?11.4470(7)??, α?=?114.086(6)°, β?=?102.290(5)°, γ?=?100.398(5)°, V?=?877.84(11) ?³, Z?=?2, T?=?150?K (Hg(Ta₂F₁₁)₂). Metal cations connected through two anions form chains along b axis. M(HF)₂(TaF₆)₂^.nHF (M?=?Cd, Hg) compounds were also prepared in the MF₂/TaF₅(M?=?Cd, Hg) system and their crystal structures were determined.

Full text of DOI:10.1016/j.jfluchem.2016.07.019

Journal of Fluorine Chemistry 189 (2016) 33–38
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
One dimensional group 12 metal undecafluoridoditantalates
*
Gašper Tavc9ar , Evgeny Goreshnik
Department of Inorganic Chemistry and Technology, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
A R T I C L E I N F O
A B S T R A C T
Article history:
The reactions between group 12 metals and the acidic TaF5 were studied in the anhydrous HF (aHF)
Received 13 June 2016
Received in revised form 21 July 2016
Accepted 26 July 2016
solvent. We were able to prepare and characterize the first compounds containing metal M2+ cations and
undecafluoridodimetallate anions – M(Ta2F11
) (M = Cd, Hg) without the additional cations, anions or
2
Available online 26 July 2016
ligands included in the crystal structure. They both crystallize in P-1 space group with cell parameters
a = 9.1571(4) Å, b = 9.8750(3) Å, c = 10.9400(7) Å,
= 94.389(4)ꢀ, = 113.124(5)ꢀ, = 101.142(3)ꢀ, V = 879.81
(8) Å3, Z = 2, T = 150 K (Cd(Ta2F11)2) and a = 9.1381(5) Å, b = 9.8613(6) Å, c = 11.4470(7) Å, = 114.086(6)ꢀ,
= 102.290(5)ꢀ, = 100.398(5)ꢀ, V = 877.84(11) Å3, Z = 2, T = 150 K (Hg(Ta2F11)2). Metal cations connected
a
b
g
Keywords:
a
Undecafluoridoditantalates
Hexafluoridotantalates
Cadmium
b
g
.
through two anions form chains along b axis. M(HF)2(TaF6)2 nHF (M = Cd, Hg) compounds were also
prepared in the MF2/TaF5 (M = Cd, Hg) system and their crystal structures were determined.
ã 2016 Elsevier B.V. All rights reserved.
Mercury
1. Introduction
6) [10]. On the other hand no M(A2F11)2 compound without
additional ligand and with metal M2+ cations have been reported
so far.
The undecafluoridodimetalate anions (A2F11À) are less common
in superacid chemistry than the monomeric AF6À species. They are
obtained when excess parent Lewis acid AF5 coordinates to
fluoride ion in the solution to form A2F11À anion. Only the strongest
Lewis acids AF5 (A = As, Sb, Ru, Ir, Bi, Nb, Ta, Pt) tend to form such
dimeric anions, but only systems containing Sb2F11À were studied
more extensively. In most of those systems counter-cation is in +1
oxidation state. There are different reports on the preparation of
pure M(AF6)2 compound prepared by the reaction between
corresponding metal difluorides and AF5 (A = As, Sb, etc.)
fluoride-ion acceptors [1,2]. However crystallization from different
solvents like SO2, CH3CN [3–5] and even anhydrous hydrogen
fluoride (aHF), that is considered a weak ligand, mostly yields
products with solvent coordinated to the metal center. UV–vis
spectra of solutions containing Lewis acids (AsF5, BF3, etc.) and MF2
in aHF show that metal centers are surrounded by HF molecules
[6], that can be removed or partially removed during the isolation.
Our intention was to prepare and study the geometry of M
(A2F11)2 compounds without the influence of additional coordi-
nated ligands or other cations that could influence its formation or
geometry. Group 12 elements were selected because related
products were observed for cadmium – (H3O)Cd(SbF6)(Sb2F11 2
)
and (H3O)2Cd(SbF6)3(Sb2F11) [7], while Hg(Ta2F11)2 in SO2 solution
was mentioned in the literature [11] without direct proof of its
existence and composition. From all the suitable AF5 Lewis acids
TaF5 was chosen as an acidic building block instead of widely used
SbF5 because it is not volatile at room temperature [12].
Consequently formed oligomers should have higher stability
during crystallization or isolation. The only drawback of the
TaF5 is its lower solubility in aHF, which could influeÀnce its
reactivity and formation of oligomeric species [13]. Ta2F11 anion
can be rarely found in the literature and in most cases it is not
structurally charaÀcterized. Examples of characterized compounds
containing Ta2F11 anion that can be found in the literature are:
O2Ta2F11, CsTa2F11, XeFTa2F11 [14], [2,4-(OMe)2C6H5][Ta2F11] [15],
À
A2F11 anions are larger than all other species in MF2/AF5/aHF
system mentioned before therefore similar could be expected for
M(A2F11 2
)
compounds with metal 2+ cations. As expected all the
TBATa2F11 [16], Hg4(Ta2F11 2
) [11].
reported compounds contain either other cations and anions
(H3O)Cd(SbF6)(Sb2F11)2, (H3O)2Cd(SbF6)3(Sb2F11) [7], AuXe2F(SbF6)
2. Results and discussion
(Sb2F11) [8] or just neutral ligands AuXe2(Sb2F11 2
)
[8], AuX-
e4(Sb2F11 2 [9], M(CO)n(Sb2F11 2 (M = Hg, Pd, Pt, Fe, Ru, Os; n = 2–
)
)
Synthesis in stoichiometric ratio between the MF2 (M = Cd, Hg)
and TaF5 (1:4) in aHF led to formation of Cd(Ta2F11 2 and Hg
)
(Ta2F11)2. Products are structurally related and both crystallize in
triclinic P-1 space group.
* Corresponding author.
E-mail address: gasper.tavcar@ijs.si (G. Tavc9ar).
http://dx.doi.org/10.1016/j.jfluchem.2016.07.019
0022-1139/ã 2016 Elsevier B.V. All rights reserved.

34
G. Tavc9ar, E. Goreshnik / Journal of Fluorine Chemistry 189 (2016) 33–38
Metal centres in crystal structures are surrounded by eight
fluorine atoms from four Ta2F11 units in deformed square antiprism
arrangement. (Figs. 1 and 2)
Both Ta2F11 groups from asymmetric unit act as bidentate
bridging ligands connecting two cadmium or mercury metal
centers into chains along b axis (Figs. 3 and 4).
Cd–F distances in the crystal structure of Cd(Ta2F11)2 are in
range from 2.251(4) to 2.410(4) Å (Fig. 1) which is similar to
distanÀces in CdF2 (2.333 Å) [17]. Both crystallographically different
Ta2F11 anions in the crystal structure are coordinated to two
different cadmium atoms as bidentate bridging ligand (Fig. 5).
All Ta–F(Cd) bond distances are elongated and are in range from
1.918(4) to 1.942(4) Å. Polarization of the anion reduces non-
bridging Ta–F distances which are in range from 1.821(4) to 1.851
(4) with the Ta–F distances opposite to Ta–F(Ta) bond being the
shortest. Bridging Ta–F(Ta) distances are from 2.056(4) to 2.077(4)
Å. Cd to Cd distances in chain are 4.901(1) and 4.976(1) Å, which is
well over the sum of Van der Waals radii, negating any possibility
of direct metal–metal bonding [18].
Hg–F distances in the crystal structure of Hg(Ta2F11)2 are in
range from 2.329(6) to 2.428(6) Å which is comparable to distances
in HgF2 2.40 Å [19]. Ta–F(Hg) distances are elongated and are in
range from 1.926(7) to 1.948(6) Å. Non-bridging Ta–F distances are
reduced similarly than in the crystal structure of Cd(Ta2F11)2.
Bridging Ta–F(Ta) distances are from 2.059(6) to 2.069(6) Å.
Distances between neighboring Hg atoms in the same chain are
4.902(1) and 4.961(1) Å, which is again longer than the sum of Van
der Waals radii [18].
Fig. 2. Coordination sphere of Hg in the crystal structure of Hg(Ta2F11)2. Thermal
ellipsoids are drawn at the 50% probability. Symmetry codes: (i) Àx, 1 À y, 1 À z; (ii)
Àx, 2 À y, 1 À z.
to staÀggered conformation [24]. Gas phase calculations show that
A2F11 anions should exist in D4h symmetry [25], which is
supported by recent crystal structure of the [2,4-(OMe)2C6H5]
À
[A2F11] (A = Nb, Ta). The A2F11 anion is completely linear in the
À
The A2F11 anions are considered weak ligands, and can be
described compound and is sandwiched between two arenium
rings. DFT calculations for that system with Nb2F11À anion showed,
that considering the interactions between a single anion and two
adjacent arenium cations, a pile arrangement is theoretically
favored, thus forcing the linearity of the Nb–F–Nb bridge.
Conversely, the calculated structure related to one ion-pair in
the gas phase shows bent Nb–F–Nb angle (159.5)ꢀ [15].
easily removed from coordination sphere of a metal cation in the
presence of stronger ligands like CO [10]. On the other hand they
tend to bend and orient themselves in such a way that they
maximize the number of interactions with the cations through
either hydrogen bonds [20,21] or act as a chelating ligands [7–
À
9,22,23]. As a consequence of those effects, A2F11 anions are
heavily distorted in practically all the crystal structures deter-
mined so far when measured by A–F–A bridge angles together with
the torsion angle between two planar SbF4eq groups from eclipsed
Bidentate coordination to two different metal atoms forces
Ta2F11À anions to adopt even more distorted shape, which is shown
in bridging Ta–F–Ta angles being 149.8(2)ꢀ and 149.9(2)ꢀ (dihedral
angles 27.5(1)ꢀ, 23.4(1)ꢀ) in the crystal structure of Cd(Ta2F11)2,
while the mercury analogue is slightly less distorted with Ta–F–Ta
angles of 151.7(3)ꢀ and 154.1(4)ꢀ (dihedral angles 16.2(2)ꢀ, 23.9
(2)ꢀ) (Fig. 6), probably as a consequence of slightly larger crystal
radius of Hg2+ (1.28, Hg2+; 1.24, Cd2+)[26]. Ta–F–Ta angle in related
mercury compound – Hg4(Ta2F11 2
)
is 153(1)ꢀ [11], which is
comparable to the ones obtained in the current study.
Such effects can also be seen in (H3O)Cd(SbF6)(Sb2F11 2
)
where
À
one Sb2F11 anion is tridentately coordinated to single cadmium
cationÀhaving Sb–F–Sb angle as low as 143.1(3)ꢀ, while the other
Sb2F11 anion with bidentate coordination has 147.9(2)ꢀ angle [7].
Type of coordination influences torsion angle to a degree that
cation and especially type of bonding to it dictates anion
conformation in a crystal structure.
Reactions of both HgF2 and CdF2 with TaF5 in 1:2 molar ratio
resulted in M(TaF6)2 type of compound as expected, but
crystallization of the product from solvent aHF ended up with
.
.
.
Cd(HF)2(TaF6)2 nHF and Hg(HF)2(TaF6)2 nHF. Cd(HF)2(TaF6)2 nHF
crystallizes in P-1 space group. Central cadmium atom has
preferred coordination number 8 and is surrounded by 6 fluorine
atoms from TaF6 units and 2 fluorine atoms from coordinated HF
molecules (Fig. 7). Basic building blocks consist of eight membered
rings containing 2 cadmium, 2 tantalum and 4 fluorine atoms that
are further connected into layers running along c axis. Cd–F(Ta)
distances are from 2.218(4) to 2.301(4) Å, while Cd–F(HF) are 2.419
(5) and 2.674(7) Å. HF(3) molecule is located outside the metal
coordination sphere between two layers and is fixed in the crystal
Fig. 1. Coordination sphere of Cd in the crystal structure of Cd(Ta2F11)2. Thermal
ellipsoids are drawn at the 50% probability. Symmetry codes: (i) 2 À x, 1 À y, 2 À z;
(ii) 2 À x, 2 À y, 2 À z.

G. Tavc9ar, E. Goreshnik / Journal of Fluorine Chemistry 189 (2016) 33–38
35
Fig. 3. Mercury atoms connected through Ta2F11 units in the crystal structure of Hg(Ta2F11)2.
space by moderate FÁ Á ÁH–F hydrogen bonds anchored to the HF(1)
molecule connected to the metal center and TaF6 unit from the
next layer (Fig. 8). However the HF is not strongly bound in the
crystal structure and rapidly evaporates from it leading to total
decomposition of the crystals in few hours as soon as the HF
atmosphere in the reaction vessel is removed. Measurements of
different crystals showed varying occupancy of HF in this position
with the highest being 0.76 which is in the attached cif (Table 1).
distort the Ta–F bonds and with it lower the symmetry of the anion
resulting in some inactive vibrations to become active and may
cause additional splitting. If we use assignation comparable to
related compounds, Raman active bands for M(TaF6)2 (M = Cd, Hg)
at 740 cmÀ1 (Cd, Hg) could be assigned to n1 stretching mode, while
bands at 682 and 662 cmÀ1 in cadmium and band at 672 cmÀ1 in
mercury compound can be a assigned to n2 stretching mode. Bands
at 295, 254 and 219 cmÀ1 in Cd(TaF6)2 and 311 and 272 cmÀ1 in Hg
(TaF6)2 can be most probably assigned to n5 bending normal modes
and the rest are lattice modes.
.
Hg(HF)2(TaF6)2 nHF crystal structure is isotypic to previously
.
described Cd(HF)2(TaF6)2 nHF (Fig. 9). Hg–F(Ta) distances are from
.
2.298(7) to 2.368(6) Å, while Hg–F(HF) are 2.529(8) and 2.667(8) Å.
Raman spectra measured on the M(HF)2(TaF6)2 nHF (M = Cd, Hg)
The stability of mercury compound is same as in Cd
(HF)2(TaF6)2 nHF with HF molecules rapidly evaporating at room
single crystals in perfluorinated oil immediately after the isolation
were identical to the Raman spectra of bulk M(TaF6)2 (M = Cd, Hg).
.
temperature. The highest measured occupancy of HF molecules
between layers in the crystal structure is 0.58.
Raman spectra of M(Ta2F11)2 (M = Cd, Hg) (Fig. 10, Table 2) are
difficult to assign due to strong deformation of highly symmetric
D4h symmetry. In any case both Cd(Ta2F11)2 and Hg(Ta2F11)2 Raman
spectra are nearly identical which can be expected from the crystal
structure, where deformation in both compounds are nearly
Assignation of bands in the synthesized products could be
difficult due to the possible presence of other phases obtained
during the synthesis in this system À especially MF(TaF6), M(TaF6)2
and MTaF7 as was reported in other systems [14]. Starting TaF5
compound consists of tetramers in solid state, which was already
proven by crystal structure and retains its oligomeric form even in
liquid [27] and to a degree in gaseous state [28]. Raman spectrum
of solid tetrameric TaF5 has the strongest bands at 755, 727, 699,
671, 273, 254, 235 cmÀ1 in C2h symmetry [29,30].
identical. Comparison to related Pd(CO)4(Sb2F11)2 shows similar
À
deformation of A2F11 anion [31]. Using the same similar trend
bands at 750 and 740 cmÀ1 in cadmium compound and 749 and
740 cmÀ1 in mercury compound can be assigned to
n(TaFax), bands
at 719, 694 and 674 cmÀ1 (719, 691 and 670 cmÀ1 for mercury) to
Raman spectra of M(TaF6)2 (M = Cd, Hg) (Fig. 10, Table 2) show
more bands than expected for regular TaF6 octahedra. Different
interactions of anion with cations and HF in solid state tend to
À
Fig. 5. Cadmium atoms connected through bridging Ta2F11 anions in the crystal
structure of Cd(Ta2F11)2. Thermal ellipsoids are drawn at the 50% probability.
Symmetry codes: (i) 2 À x, 2 À y, 2 À z.
Fig. 4. Chains along b axis in the crystal structure of Hg(Ta2F11)2.

36
G. Tavc9ar, E. Goreshnik / Journal of Fluorine Chemistry 189 (2016) 33–38
Fig. 6. Bridging Ta2F11À anion in the structure of Hg(Ta2F11)2. Thermal ellipsoids
are drawn at the 50% probability.
Fig. 8. Packing of layers in the crystal structure of Cd(HF)2(TaF6)2.nHF.
4. Experimental
n
(TaF4eq), band at 309 cmÀ1 (301 cmÀ1 for mercury) to
bands at 244 and 191 cmÀ1 (247 and 188 cmÀ1 for mercury) to
(TaF4eq) and band at 135 cmÀ1 (131 cmÀ1 for mercury) to
(FTaF).
d(TaFax),
d
d
4.1. Apparatus, reagents and general experimental procedures
3. Conclusions
Anhydrous HF (aHF) was handled on a part of vacuum line made
from Teflon, PFE, and FEP in order to diminish corrosion. Pressures
were measured by means of a Monel Helicoid pressure gauge (0–
3000 Torr Æ0.25%) connected to the vacuum manifold with a Teflon
valve. Moisture-sensitive materials were handled in the dry argon
atmosphere of a glove box (water content of ꢁ0.1 ppm; M. Braun,
Germany).
Vacuum line used to carry out the reactions was coupled to a
mechanical pump and oil diffusion pump. aHF was removed on the
vacuum line with traps cooled by liquid nitrogen. Reaction vessels,
made of PFA and equipped with Teflon valves and Teflon coated
stirring bars, were used for the syntheses. Crystals were grown in a
crystallization vessel, made from a T-shaped FEP reaction vessel
constructed from a 16-mm i.d. length of FEP tube and a length of 4-
mm i.d. FEP tubing connected to a Teflon valve. Saturated solutions
in aHF were decanted from one arm of the crystallization vessel to
the other. A temperature gradient was maintained between both
arms in order to induce crystal growth.
From all the so far known undecafluoridodimetallate com-
pounds with divalent cations only M(Ta2F11)2 (M = Cd, Hg) exist in
compound without additional ligands or ions. All the other
compounds contain other ligands, anions or cations that interfere
with their packing. Obtained compounds crystallize in P-1 space
group. Ta2F11 units act as bidentate bridging ligand connecting two
metal divalent cations forming one dimensional chains in the
crystal structure. Dimeric anion tends to bend Ta–F–Ta angle to
such a degree that it reaches the highest number of interactions
with cations and are far away from ideal D4h symmetry. On the
other hand this deformation prevents the anion form forming
interactions between chains therefore infinite one dimensional
chains are observed.
Reagents. CdF2 (99.9%, Alfa Aesar) and TaF5 (99.9%, Alfa Aesar)
were used as supplied. HgF2 was prepared by high temperature
(503 K) fluorination of HgCl2 (99%, Merck) in 100 ml nickel
autoclave. Anhydrous HF (3.5, Linde) was treated with K2NiF6
(Ozark-Mahoning, 99%) for several days prior to use. Caution:
Reactions with anhydrous hydrogen fluoride and TaF5 must be
carried out in a well-ventilated hood and protective clothing must
be worn at all times. The experimentalist must become familiar
with these reagents and the hazards associated with them. Fresh
tubes of calcium gluconate gel should always be on hand for the
immediate treatment of skin exposed to these reagents. For a full
protocol for the treatment of HF exposures see reference [32].
Synthesis of M(TaF6)2 (M = Cd, Hg). The Cd(TaF6)2 was synthe-
sized from CdF2 (0.136 g; 0.90 mmol) and stoichiometric amount of
solid TaF5 (0.499 g; 1.81 mmol) in aHF solvent in quantitative yield.
Solvent was pumped off on the vacuum line and the product was
characterized by the Raman spectroscopy.
Hg(TaF6)2 was synthesized from HgF2 (0.500 g; 2.10 mmol) and
stoichiometric amount of solid TaF5 (1.160 g; 4.20 mmol) in aHF
solvent in quantitative yield. Solvent was pumped off on the
vacuum line and the product was characterized by the Raman
spectroscopy.
Synthesis of M(Ta2F11 2 (M = Cd, Hg). The Cd(Ta2F11)2 was
synthesized from CdF2 (0.030 g; 0.20 mmol) and stoichiometric
amount of solid TaF5 (0.220 g; 0.80 mmol) in aHF solvent in
)
Fig. 7. Coordination of Cd in the crystal structure of Cd(HF)2(TaF6)2.nHF. Thermal
ellipsoids are drawn at the 50% probability. Symmetry codes: (i) 1 + x, y, z; (ii) 1 À x,
1 À y, 1 À z; (iii) 1 À x, 1 À y, 2 À z.

G. Tavc9ar, E. Goreshnik / Journal of Fluorine Chemistry 189 (2016) 33–38
37
Table 1
Crystal Data and structural Refinementa.
b
Cd(Ta2F11
)
2
Hg(Ta2F11
)
2
Ta4F20
Cd(HF)2(TaF6)2.nHF
Hg(HF)2(TaF6)2.nHF
a (Å)
b (Å)
c (Å)
a
b
g
V (Å3)
9.1571(4)
9.8750(3)
9.1381(5)
9.8613(6)
9.5386(3)
14.3655(3)
5.0042(1)
5.6993(3)
9.7763(6)
10.0580(6)
98.691(5)
90.432(5)
103.232(5)
538.76(6)
2
5.7076(1)
9.7665(2)
10.1663(2)
98.906(2)
91.013(2)
102.285(2)
546.29(2)
2
10.9400(7)
94.389(4)
113.124(5)
101.142(3)
879.81(8)
2
11.4470(7)
114.086(6)
102.290(5)
100.398(5)
877.84(11)
2
(ꢀ)
(ꢀ)
(ꢀ)
97.332(3)
680.10(3)
2
Z
Formula weight
Space Group
T (ꢀC)
703.76
P-1
À123(1)
0.71073
4.734
26.166
0.0316
0.0638
1342.39
P-1
À123(1)
0.71073
5.078
33.750
0.0497
0.0949
275.95
C2/m
À123(1)
0.71073
5.390
32.298
0.0202
0.0324
757.53
P-1
À123(1)
0.71073
4.670
22.401
0.0328
0.0934
842.11
P-1
À123(1)
0.71073
5.117
34.177
0.0364
0.0950
l
r
m
(Å)
calcd (g/cm3)
(mmÀ1
)
R1
wR2
a
2
R1
=
S
||Fo| À |Fc||/
S
|Fo|, wR2 = [
S
(w(Fo À Fc2)2)/
S .
(w(Fo2)2]1/2
b
redetermined.
quantitative yield. After the reaction was completed solvent was
pumped off on the vacuum line. The product was characterized by
the Raman spectroscopy.
crystal was selected under the microscope and transferred into the
cold nitrogen stream (150 K) of the X-ray diffractometer. Such
temperature was chosen, because crystals were cracking during
the transfer into the cold nitrogen stream at lower temperatures.
The Hg(Ta2F11 2
)
was synthesized from HgF2 (0.100 g;
.
0.42 mmol) and stoichiometric amount of solid TaF5 (0.463 g;
1.68 mmol)in aHF solvent in quantitative yield. After the reaction
was completed solvent was pumped off on the vacuum line. The
product was characterized by the Raman spectroscopy.
Growth of Single Crystals of M(HF)2(TaF6)2 nHF (M = Cd, Hg).
Stoichiometric amounts of MF2 and TaF5 (Cd: 0.100 g CdF2, 0.367 g
TaF5; Hg: 0.050 g HgF2, 0.116 g TaF5) were weighed in the glove box
and put into the wider part of the crystallization vessel and
dissolved in aHF. The crystals were grown with a temperature
gradient of 28 K. When almost all the mother liquor had
evaporated to the cooled part of crystallization vessel, cold
perfluorinated oil (ABCR, FO5960) was injected in the reaction
vessel with a syringe and suspension of crystals in oil was
transferred under the microscope immediately. A suitable crystal
was selected under the microscope and transferred into the cold
nitrogen stream of the X-ray diffractometer.
4.2. Preparation of single crystals
Growth of Single Crystals of M(Ta2F11)2 (M = Cd, Hg). Stoichio-
metric amounts of MF2 and TaF5 were weighed in the glove box and
put into the wider part of the crystallization vessel and dissolved in
aHF. The crystals were grown with a temperature gradient of 28 K
and were isolated by decantation of the mother liquor and were
than sealed in the part of the vessel where they were grown and
transferred to the glove box. The obtained crystals were immersed
in perfluorinated oil (ABCR, FO5960) in a glove box. A suitable
4.3. X-ray structure determination
Single-crystal data for all compounds were collected on a
Gemini A diffractometer equipped with an Atlas CCD detector,
using graphite monochromated MoKa radiation. The data were
treated using the CrysAlisPro software suite program package [33].
Analytical absorption correction has been applied to all data sets.
Structures were solved with direct methods using the SHELXS
program [34] or with charge-flipping method using the Superflip
Fig. 9. Packing of layers in the crystal structure of Hg(HF)2(TaF6)2.nHF. Thermal
ellipsoids are drawn at the 50% probability. Symmetry codes: (i) 1 + x, y, z; (ii) 1 À x,
1 À y, 1 À z; (iii) 1 À x, 1 À y, 2 À z.
Fig. 10. Comparison of Raman spectra of Cd(Ta2F11)2, Hg(Ta2F11)2, H3OTaF6, TaF5, Hg
(HF)2(TaF6)2.nHF and Cd(HF)2(TaF6)2.nHF.

38
G. Tavc9ar, E. Goreshnik / Journal of Fluorine Chemistry 189 (2016) 33–38
Table 2
Comparison of Raman bands of synthesized compounds in solid state in this systema.
*
TaF5
H3OTaF6
Cd(HF)2(TaF6)2
.nHF
Hg(HF)2(TaF6)2
.nHF
Cd(Ta2F11
)
Hg(Ta2F11)
2
2
755
724
698
(100)
(12)
(25)
750
740
719
694
674
309
(100)
(13)
(8)
(8)
(8)
749
740
719
691
670
301
(100)
(20)
(6)
(6)
(12)
(15)
711
(100)
(30)
740
682
662
(100)
(18)
(5)
740
672
(100)
(12)
295
(13)
311
272
(17)
(11)
(16)
271
235
(28)
(7)
284
254
219
181
164
(8)
(7)
(7)
(5)
244
(6)
247
(32)
200
141
(6)
(24)
191
135
(7)
(7)
188
131
(11)
(8)
*
Reference [38,39].
a
Vibrational frequencies are in cmÀ1, and relative intensities are given in parentheres.
program [35] (Olex crystallographic software [36]). The electron
density map, obtained by Superflip software, was analysed by
EDMA program [37], which gave initial models of structures.
Structure refinement has been performed with the SHELXL-2014
software [38], implemented in the program package WinGX [39].
Figures were prepared using Diamond 3.2 software [40]. The data
can be ordered free of charge from the Crystal Structure Depot at
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Appendix A. Supplementary data
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