Synthesis and structural properties of the first bismuth(III) telluroether complex

Article abstract of DOI:10.1039/b209321a

The first donor-acceptor complexes of Sb(III) and Bi(III) with telluroether ligands are reported, together with the crystal structure of [BiBr₃(PhTeMe)].

Full text of DOI:10.1039/b209321a

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Synthesis and structural properties of the first bismuth(III)
telluroether complex
William Levason, Nicholas J. Hill and Gillian Reid
Department of Chemistry, University of Southampton, Highfield, Southampton, UK SO17 1BJ.
E-mail: gr@soton.ac.uk
Received 23rd September 2002, Accepted 22nd October 2002
First published as an Advance Article on the web 1st November 2002
The first donor–acceptor complexes of Sb(III) and Bi(III)
with telluroether ligands are reported, together with the
crystal structure of [BiBr3(PhTeMe)].
Recently we have reported on a new series of main group
coordination complexes involving Group 15 trihalides (MX3,
M = As, Sb, Bi; X = Cl, Br, I) with polydentate and macrocyclic
thio- and seleno-ether ligands.1–4 Within this class of com-
pounds several unprecedented structural motifs have been
characterised, the precise nature of which is apparently
determined by a combination of primary and secondary
bonding interactions and the degree of influence of the
M-based lone pair of electrons. Highlights include the discrete
4 : 1 species [(AsCl3)4([24]aneSe6)] ([24]aneSe6 = 1,5,9,13,17,21-
hexaselenacyclotetracosane)3 where a weakly associated Cl2-
As(µ-Cl2)AsCl2 dimer unit lies within the ring and two AsCl3
units lie exo, and [BiCl3{MeS(CH2)3SMe}] which contains
pseudo-cubane Bi4Cl4 core units linked by bridging dithioethers
into a 3-D network and containing large channels.4 In view of
the gross structural variations which occur through subtle
modifications of the reagents or conditions, we were interested
to examine the reactions of the heavier telluroether ligands with
these Group 15 acceptors.
In general, telluroether chemistry is hampered by difficulties
in the formation of Te–C linkages and their susceptibility to
elimination of the organic units giving ditellurides and elem-
ental tellurium.5 Coordination to transition metal fragments,
especially in high oxidation states, also tends to promote
decomposition via reduction and dealkylation. At present their
coordination chemistry is almost exclusively associated with
middle to late transition metal ions in low or medium oxidation
states, although it is clear that telluroether ligands are better
σ-donors to low valent transition metals than their thio- or
seleno-ether analogues.6
In terms of the p-block, the only examples of telluroether
complexes are with SnX4 (X = Cl or Br) and two examples, cis-
[SnX4{o-C6H4(TeMe)2}], have been structurally authenticated
revealing distorted octahedral geometries.7
Fig. 1 (a) View of the crystal structure of the dimeric unit in
[BiBr3(PhTeMe)] with numbering scheme adopted. The symmetry
related atoms Bi(1a) and Br(1a) are generated by the symmetry
operation 1 Ϫ x, 1 Ϫ y, Ϫz. Ellipsoids are shown at the 40% probability
level. Selected bond lengths (Å) and angles (Њ): Bi(1)–Te(1) 3.0533(7),
Bi(1)–Br(1) 2.8291(10), Bi(1)–Br(1a) 3.0810(10), Bi(1)–Br(2) 2.6497(9),
Bi(1)–Br(3) 2.8570(9); Te(1)–Bi(1)–Br(1) 92.30(3), Te(1)–Bi(1)–Br(1a)
84.14(2), Te(1)–Bi(1)–Br(2) 90.92(2), Te(1)–Bi(1)–Br(3) 87.53(2), Br(1)–
Bi(1)–Br(1a) 87.84(3), Br(1)–Bi(1)–Br(2) 92.45(3), Br(1)–Bi(1)–Br(3)
171.47(3), Br(1a)–Bi(1)–Br(2) 175.05(3), Br(1a)–Bi(1)–Br(3) 83.66(3),
Br(2)–Bi(1)–Br(3) 96.08(3). (b) View of [BiBr3(PhTeMe)] showing the
interdimer Bi ؒ ؒ ؒ Br contacts generating the infinite chains.
We have investigated the reactions of various MX3 (M = As,
Sb, Bi; X = Cl, Br, I) with MeTe(CH2)3TeMe in anhydrous
MeCN solution (or thf for X = I). We were unable to isolate any
solids from the As() reactions (probably owing to the poor
Lewis acidity of AsX3), however, using Sb and Bi salts allowed
us to isolate orange–brown, analytically pure samples of a
limited set of compounds, [SbX3{MeTe(CH2)3TeMe}] (X = Br
or I), [BiCl3{MeTe(CH2)3TeMe}] and [BiBr3(PhTeMe)] in
modest to good yields.† These are the first examples of
antimony and bismuth telluroether species, and, other than the
tellurolate compounds [M{TeSi(SeMe3)3}3] (M = Sb or Bi)
synthesised by Arnold and co-workers,8 they are the only
known complexes involving Sb–Te or Bi–Te bonds.
The isolated solids exhibit very poor solubility in chloro-
carbons, MeCN and MeNO2, hence severely hampering our
attempts to obtain crystalline samples. We were however
successful in obtaining red crystals of the compound
[BiBr3(PhTeMe)] by slow evaporation from an MeCN solution
of BiBr3 which had been layered with an equimolar solution of
PhTeMe in CH2Cl2. The crystal structure‡ shows (Fig. 1a) a
planar asymmetric Br2Bi(µ-Br)2BiBr2 dimer unit with one
PhTeMe ligand coordinated apically to each Bi and occupying
mutually anti positions. Br(3) and Br(3b) form additional long
contacts (3.16 Å) via the open Bi vertex and hence link adjacent
units to give an infinite chain of Bi2Br6(PhTeMe)2 dimers in a
step-like arrangement (Fig. 1b). The Bi–(µ-Br) distances differ
by ca. 0.25 Å, whereas in structurally related compounds such
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J. Chem. Soc., Dalton Trans., 2002, 4316–4317
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DOI: 10.1039/b209321a

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as the dianionic [Bi2I8(SMe2)2]2–9 and the selenacrown complex
[BiBr3([16]aneSe4)] ([16]aneSe4 = 1,5,9,13-tetraselenacyclohexa-
decane)2 the bridging halides are essentially symmetrical. The
Bi centres in the present structure are therefore pseudo-
octahedral and it seems likely that the Bi-based lone pair is
probably directed out of the triangular face defined by Br(1a),
Br(3) and Br(3b) i.e. involving the longer Bi–Br contacts.
The Bi–Te distance of 3.0533(7) Å indicates that this is a
strong bond, only marginally longer than the sum of the
covalent radii of the elements (2.89 Å). As these are the first
structural data on a Bi–Te bonded species and there are no
direct analogues with thio- or seleno-ether ligands, meaningful
comparisons are difficult. However, the dianion [Bi2I8(SMe2)2]2Ϫ
in which the SMe2 ligands are also anti (but trans to I), shows
d(Bi–S) = 3.054(8) Å9 and [BiBr3([16]aneSe4)], which also
contains a planar Br2Bi(µ-Br)2BiBr2 unit (but mutually trans
Se atoms)2 gives d(Bi–Se) = 2.952(2) and 3.095(2) Å. Thus,
the bismuth–chalcogen bond distances in these compounds are
not significantly different from the title compound despite the
much larger radius of Te vs. Se and S. The availability of
bismuth telluroether complexes and the relatively strong Bi–Te
bonds may indicate that such compounds could function as
single source precursors to the thermoelectric material Bi2Te3.10
The infinite structure identified for [BiBr3(PhTeMe)] is
unprecedented in Group 15 halide-chalcogenoether chemistry.
Structurally the closest analogues are with phosphine and
arsine ligands, e.g. the discrete dimer [As2Cl6(AsEt3)2],11 the
polymeric [AsCl3(PMe3)]10 and especially [SbI3(PMe3)]13 which
shows a very similar packing arrangement within the crystal
lattice.
[BiBr3(PhTeMe)]: Procedure as above. Yield 22%. Red–brown
powder. (Calc. for C7H8BiBr3Te: C, 12.6; H, 1.2. Found: C, 12.3; H,
0.9%).
‡ Crystal data for [BiBr3(PhTeMe)]: C7H8BiBr3Te (Mr = 668.43), mono-
clinic, P21/n, a = 8.4820(2), b = 6.7592(2), c = 22.5808(8) Å, β =
100.6760(10)Њ, V = 1272.18(6) Å3, Z = 4, Dc = 3.490 g cmϪ3, µ(Mo-Kα) =
25.486 cmϪ1, T = 120 K, R = 0.039, Rw = 0.037 for 109 parameters
against 2144 reflections with I > 2σ(I ) out of 2956 unique reflections.
Structure solution and refinement were routine.14–16 CCDC reference
number 194426. See http://www.rsc.org/suppdata/dt/b2/b209321a/ for
crystallographic data in CIF or other electronic format.
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Notes and references
† [SbBr3{MeTe(CH2)3TeMe}]: To an anhydrous MeCN solution of
SbBr3 (0.09 g, 0.25 mmol) was added an equimolar quantity
of MeTe(CH2)3TeMe in MeCN. The resulting orange solution was
stirred at RT for 30 min and then concentrated in vacuo to afford an
orange powder which was filtered, washed with anhydrous CH2Cl2 and
dried in vacuo. Yield 74%. (Calc. for C5H12Br3SbTe2: C, 8.7; H, 1.7.
Found: C, 8.5; H, 1.9%).
[SbI3{MeTe(CH2)3TeMe}]: Procedure as above but using thf. Yield
82%. Red powder. (Calc. for C5H12I3SbTe2: C, 7.2; H, 1.5. Found: C,
7.2; H, 2.1%).
[BiCl3{MeTe(CH2)3TeMe}]: Procedure as above and using MeCN.
Yield 44%. Brown powder. (Calc. for C5H12BiCl3Te2: C, 9.3; H, 1.9.
Found: C, 9.4; H, 2.1%).
15 TeXsan: Crystal Structure Analysis Package, Molecular Structure
Corporation, Texas, 1995.
16 R. H. Blessing, Acta Crystallogr., Sect. A, 1995, 51, 33.
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