The bicyclic polyselenium cation Se102+ in the structure of Se10[Bi4Cl14]

Article abstract of DOI:10.1002/zaac.201000165

In the ternary system Se/Bi/Cl a new polycation containing phase besides the already known Se₄[Bi₄Cl₁₄], Se ₈[Bi₄Cl₁₄], and Se₁₀[Bi ₅Cl₁₇] was discovered. Red, transparent, plate shaped crystals of Se₁₀[Bi₄Cl₁₄] were formed by reaction of Se/SeCl₄/BiCl₃ in 15:1:8 molar ratio in evacuated glass ampoules applying a temperature gradient from 90 to 80 °C. The crystal structure consists of bicyclic Se₁₀²⁺ cations and of layered chloridobismutate anions with the cations located between the anionic planes. The atoms of the cation form a six membered ring with a Se ₄ chain bridging over the 1,4 positions of the Se₆ ring. The anions are made up of BiCl₇ polyhedra connected by common edges to layers ²_∞[Bi₄Cl₁₄ ^2-]. Se₄[Bi₄Cl₁₄], Se ₈[Bi₄Cl₁₄], Se₁₀[Bi ₄Cl₁₄], and Te₈[Bi₄Cl₁₄] all contain an anion of identical formula and two-dimensional connectivity, but these polymeric chlorido-bismutates are not isostructural. The structural differences are discussed on basis of the different topologies of the nets made up by the bismuth atoms.

Full text of DOI:10.1002/zaac.201000165

SHORT COMMUNICATION
DOI: 10.1002/zaac.201000165
2+
The Bicyclic Polyselenium Cation Se10 in the Structure of Se10[Bi4Cl14]
Johannes Beck*[a] and Steffen J. Eck[a]
Keywords: Selenium; Clusters; Polycations; Chloridobismutates; Bismuth
Abstract. In the ternary system Se/Bi/Cl a new polycation containing membered ring with a Se4 chain bridging over the 1,4 positions of the
phase besides the already known Se4[Bi4Cl14], Se8[Bi4Cl14], and Se6 ring. The anions are made up of BiCl7 polyhedra connected by
Se10[Bi5Cl17] was discovered. Red, transparent, plate shaped crystals common edges to layers 2∞[Bi4Cl142–]. Se4[Bi4Cl14], Se8[Bi4Cl14],
of Se10[Bi4Cl14] were formed by reaction of Se/SeCl4/BiCl3 in 15:1:8 Se10[Bi4Cl14], and Te8[Bi4Cl14] all contain an anion of identical for-
molar ratio in evacuated glass ampoules applying a temperature gradi- mula and two-dimensional connectivity, but these polymeric chlorido-
2+
ent from 90 to 80 °C. The crystal structure consists of bicyclic Se10
bismutates are not isostructural. The structural differences are dis-
cations and of layered chloridobismutate anions with the cations lo- cussed on basis of the different topologies of the nets made up by the
cated between the anionic planes. The atoms of the cation form a six bismuth atoms.
Glass ampoules of 12 cm length and 1.4 cm diameter were filled with
selenium, SeCl4, and BiCl3 in the molar ratio 15:1:8 in a total amount
Introduction
Bismuth trichloride is a strong Lewis acid. It reacts with
chloride ion donors with formation of chloridobismutates.
of 300 mg. The ampoules were evacuated, sealed and placed in a hori-
zontal tube furnace. After keeping at 80 °C for 4 hours, a temperature
[BiCl4]– is formally the first product, but since Bi3+ ions prefer gradient 90 to 80 °C was applied along the ampoule for 36 hours.
Besides the main products Se4[Bi4Cl14] and Se10[Bi5Cl17], red transpar-
ent plate shaped crystals were deposited along the walls of the reaction
ampoule.
higher coordination numbers between six and eight, it is gener-
ally observed that variable amounts of BiCl3 associate with
tetrachloridobismutate with formation of chloridobismutates of
higher nuclearity. The weak donor strength of these chlorido-
bismutates is obvious in their ability to stabilise “naked” poly-
cationic clusters of the elements of the chalcogens [1]. In the
ternary system Se/Bi/Cl three compounds containing polyca-
Crystals were isolated by immersing in cold perfluorinated oil. Diffrac-
tion data were recorded with a Bruker Nonius CCD diffractometer at
low temperature generated with a cold nitrogen stream. The space
group was derived from the reciprocal lattice extinctions as P212121
and the non-centrosymmetry was confirmed during the refinements.
tionic clusters were already discovered: Se4[Bi4Cl14], contain-
2+
ing the square planar Se4 ion [2], Se8[Bi4Cl14], containing The structure was solved by direct methods [4] and refined with aniso-
2+
tropic displacement parameters for all atoms [5]. A Flack x parameter
of –0.042(4) showed the absence of inversion twinning [6]. An empiri-
cal absorption correction was applied to the data [7]. Further details
on the crystal structure investigation may be obtained from the Fachin-
formationszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen, Ger-
many (Fax: +49-7247-808-666; E-Mail: crysdata@fiz-karlsruhe.de),
on quoting the depository number CSD-421619 [8]. For the graphical
representations the program DIAMOND was used [9].
the bicyclic Se8 ion [2], and Se10[Bi5Cl17] with the bicyclic
2+
Se10 cluster ion [3]. We discovered a fourth phase in this
system and report on the synthesis and structure of
Se10[Bi4Cl14].
Experimental Section
Bismuth and selenium were used as commercial products. Bismuth
was purified by melting under argon protecting gas and decanting the
melt from the black residue. SeCl4 and BiCl3 were prepared by reaction
of the elements with Cl2. The chlorine gas was purified by condensing
to the liquid state at –75 °C in a U-shaped vessel. The Cl2 gas stream
for the chlorination reaction was established by bubbling argon gas
through the cold, liquid chlorine. SeCl4 and BiCl3 were both subli-
mated in the Cl2/Ar stream. All further manipulations like charging
and opening of the reaction ampoules were performed in an argon
filled glove box.
Results and Discussion
Se10[Bi4Cl14] is formed in the reaction of selenium, SeCl4,
and BiCl3 besides the related phases Se4[Bi4Cl14],
Se10[Bi5Cl17], and Se8[Bi4Cl14]. Small differences in the reac-
tion conditions favour the formation of one of the different
compounds. For the synthesis of Se10[Bi4Cl14], the reaction
conditions were found to be optimal at a Se/SeCl4/Bi ratio of
15:1:8 and a temperature of 90 °C. The crystals are deposited
from the gas phase and can be distinguished visually by their
thin platy shape from the neighbouring phases.
* Prof. Dr. J. Beck
E-Mail: j.beck@uni-bonn.de
[a] Institut für Anorganische Chemie
Universität Bonn
2+
The crystal structure consists of discrete Se10 cations and
Gerhard-Domagk-Str. 1
53121 Bonn, Germany
of polymeric chloridobismutate anions 2∞[Bi4Cl142–]. The cation
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Z. Anorg. Allg. Chem. 2010, 636, 1910–1912

2+
The Polyselenium Cation Se10 in the Structure of Se10[Bi4Cl14]
(Figure 1) is built of a six-membered ring in boat conformation
bearing a Se4 chain bridging over the 1,4 positions of the Se6
ring. The Se–Se bonds show the typical separation in short
bonds around 2.29 Å at the dicoordinate selenium atoms and
long bonds around 2.43 Å at the tricoordinate selenium atoms.
The Se–Se–Se angles are almost equalised in the narrow range
between 99.73(4) and 102.68(4) °. The structure of the cation
is thus analogous to the ions found in the structures of
Se10[SbF6]2 [10], Se10[AlCl4]2 [10], Se10[SO3F]2 [11], and
Se10[Bi5Cl17] [3]. The crystal structure is acentric. Since the
2+
structure of the Se10 ion allows only for a twofold axis as
the only symmetry operation, which is approximately fulfilled
in the presented structure, the ion is enantiomorphic.
Figure 2. The four independent bismuth atoms in the structure of
Se10[Bi4Cl14] and their coordination by surrounding chlorine atoms
with Bi–Cl distances up to 3.4 Å. The thermal ellipsoids represent a
probability level of 50 %. Symmetry operations: I = –½+x, –½–y, –z;
II = –1+x, y, z; III = –½+x, ½–y, –z; IV = 1+x, y, z; V = ½+x, ½–y, –
z. The inset on the bottom shows the distribution of the Bi–Cl bond
lengths in form of a histogram. The arrow indicates the upper limit of
Bi–Cl bonds at 3.4 Å taken into account.
2+
Figure 1. The Se10 cationic cluster in the structure of Se10[Bi4Cl14].
The thermal ellipsoids represent a probability level of 50 %. Bond
lengths /Å: Se(1)–Se(2) 2.421(2), Se(1)–Se(6) 2.423(2), Se(1)–Se(7)
2.447(2), Se(2)–Se(3) 2.261(2), Se(3)–Se(4) 2.457(2), Se(4)–Se(5)
2.392(2), Se(4)–Se(10) 2.437(2), Se(5)–Se(6) 2.269(2), Se(7)–Se(8)
2.285(2), Se(8)– Se(9) 2.361(2), Se(9)–Se(10) 2.277(2).
The Bi–Cl bonds in the chloridobismutate anion are spread
over a wide range beginning from 2.490(2) Å (Bi(1)–Cl(1)).
A first large gap in the bond lengths is present after Bi(3)–
Cl(2)IV = 3.379(2) Å (Figure 2). If all Bi–Cl distances up to
this limit are taken into account, all four independent bismuth
atoms obtain coordination polyhedra with coordination number
seven. These polyhedra are connected via common edges to
2+
layers spread out in the crystallographic ab plane. The Se10
cations are embedded between the layers of the polymeric ani-
ons (Figure 3).
Four compounds are now known, which all contain the
[Bi4Cl14]2– anion, Se4[Bi4Cl14] Se8[Bi4Cl14], Se10[Bi4Cl14], and
Te8[Bi4Cl14] [12]. It is remarkable that the anions in all four
structures are not isostructural, despite the identical formula
and the shared structural feature of forming two-dimensional
arrangements. The differences between the anions, but also
their relationship, can be understood if, for simplification, only
Figure 3. The unit cell of Se10[Bi4Cl14] in 2a view along the crystallo-
graphic c axis. Shown is one layer of the [Bi4Cl142–] anion and the
∞
directly neighboured Se102+ cations. The thermal ellipsoids represent a
probability level of 50 %.
the arrangement of the bismuth atoms is considered. The re- metry of Se4[Bi4Cl14] as the representative with the highest
spective nets of the bismuth atoms are depicted in Figure 4. symmetry. Orthorhombic Se10[Bi4Cl14] and triclinic
The nets present in the structures of the selenium containing Se8[Bi4Cl14] are distorted variants. The three nets share the
compounds Se8[Bi4Cl14] (a), Se10[Bi4Cl14] (b), and same connection type, expressed by the Schläfli symbol 3342
Se4[Bi4Cl14] (c) are closely related. They show an arrangement [13]. The arrangement of triangles and quadrangles is different
of the bismuth atoms analogous to the motif of the oxide ions in the net belonging to the structure of Te8[Bi4Cl14] (d), but
in the rutile structure. This is in line with the tetragonal sym- the connection type 3342 is also valid for this arrangement.
Z. Anorg. Allg. Chem. 2010, 1910–1912
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1911

J. Beck, S. J. Eck
SHORT COMMUNICATION
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0.054; Flack x parameter –0.042(4); max. /min. residual density
+1.61 / –1.80 e·Å–3.
Figure 4. The nets of bismuth atoms in a layer of the [Bi4Cl14]2– anions
in the structures of Se8[Bi4Cl14] (a), Se10[Bi4Cl14] (b), Se4[Bi4Cl14] (c),
Te8[Bi4Cl14] (d), all in a view perpendicular to the plane of the nets.
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unit cell edges are given with thin lines. The nets are not planar since
the height differences of the bismuth atoms perpendicular to the view-
ing direction amount between 3 and 3.5 Å.
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Acknowledgement
[12] J. Beck, A. Stankowski, Z. Naturforsch. 2001, 56b, 453–457.
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The authors thank Dr. Jörg Daniels, Inorganic Chemistry Institute of
University of Bonn, for encouraging help with the isolation of suitable
crystals and for the recording of the diffraction data set.
Received: April 10, 2010
Published Online: June 17, 2010
1912
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© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2010, 1910–1912