Soft-soft interactions of iodide and triiodide ions with triphenyltelluronium cations

Article abstract of DOI:10.1080/10426501003773779

The crystal structures of triphenyltelluronium iodide and of triphenyltelluronium triiodide were solved by X-ray diffraction. Triphenyltelluronium iodide consists of ladder-like tetrameric units involving dicoordinated iodine atoms, bridging penta- and hexacoordinated tellurium atoms, and tri-coordinated central iodines that bridge one pentacoordinated and two hexacoordinated tellurium atoms. Triphenyltelluronium triiodide is made up of extended chains that are generated by pairwise interaction of Ph ₃Te-I₃ units through weak Te···I contacts involving one terminal atom from each triiodide ion, and by connection of these four-membered units through both terminal atoms of the triiodide ions. This asymmetric contribution of the two terminal iodine atoms of the triiodide ion to the soft-soft network correlates with a significant difference of the two I-I bond lengths (2.847 and 2.984 A). Copyright Taylor & Francis Group.

Full text of DOI:10.1080/10426501003773779

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Phosphorus, Sulfur, and Silicon and the
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Soft–Soft Interactions of Iodide and
Triiodide Ions with Triphenyltelluronium
Cations
Wolf-W. du Mont a , Jörg Jeske a & Peter G. Jones a
a Institut fuer Anorganische und Analytische Chemie , Technische
Universitaet Braunschweig , Braunschweig, Germany
Published online: 27 May 2010.
To cite this article: Wolf-W. du Mont , Jörg Jeske & Peter G. Jones (2010) Soft–Soft Interactions of
Iodide and Triiodide Ions with Triphenyltelluronium Cations, Phosphorus, Sulfur, and Silicon and the
Related Elements, 185:5-6, 1243-1249, DOI: 10.1080/10426501003773779
To link to this article: http://dx.doi.org/10.1080/10426501003773779
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Phosphorus, Sulfur, and Silicon, 185:1243–1249, 2010
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426501003773779
SOFT–SOFT INTERACTIONS OF IODIDE AND TRIIODIDE
IONS WITH TRIPHENYLTELLURONIUM CATIONS
Wolf-W. du Mont, Jo¨rg Jeske, and Peter G. Jones
Institut fuer Anorganische und Analytische Chemie, Technische Universitaet
Braunschweig, Braunschweig, Germany
The crystal structures of triphenyltelluronium iodide and of triphenyltelluronium triio-
dide were solved by X-ray diffraction. Triphenyltelluronium iodide consists of ladder-like
tetrameric units involving dicoordinated iodine atoms, bridging penta- and hexacoordinated
tellurium atoms, and tri-coordinated central iodines that bridge one pentacoordinated and
two hexacoordinated tellurium atoms. Triphenyltelluronium triiodide is made up of extended
. . .
chains that are generated by pairwise interaction of Ph3Te-I3 units through weak Te
I
contacts involving one terminal atom from each triiodide ion, and by connection of these
four-membered units through both terminal atoms of the triiodide ions. This asymmetric
contribution of the two terminal iodine atoms of the triiodide ion to the soft–soft network
correlates with a significant difference of the two I I bond lengths (2.847 and 2.984 A).
Keywords Secondary interactions; soft–soft interactions; telluronium salts; triiodide; X-ray
crystallography
INTRODUCTION
Organic selenonium and telluronium iodides R3E+ I− (E = Se, Te) can be described as
essentially ionic compounds, but their solid state structures structures reveal that directed
electronic interactions of the type n(halide) →σ∗(E C) play a role in determining the
contacts between pyramidal R3E+ cations and X− anions.1
Crystalline Me3SeI involves pairs of pyramidal Me3Se+ cations and iodide anions.
. . .
The Se I distance (378 pm) is shorter than the sum of Se and I van der Waals radii (415 pm)
. . .
and is also shorter than the S I distance in the sulfur analogue (389 pm). The Se I contact
and one of the Se C bonds are almost collinear, i.e., the coordination environment of Se can
be regarded as ψ-trigonal-bipyramidal.2 The phenyl derivative Ph3SeI exhibits a slightly
3
. . .
shorter Se I contact (372.2 pm) than in Me3SeI.
Telluronium cations R3Te+ tend to give higher aggregates with pentacoordinated
monocapped-octahedral tellurium atoms (14–Te–6).1,4–7 In [Me3Te+ Cl− · H2O], the tel-
. . .
. . .
lurium atom is involved in two Te Cl contacts approximately trans to Te C, and one
. . .
further long O Te contact (308.9 pm); hydrogen bonding between H2O and Cl leads to
infinite chains. Solid Ph3TeCl. 1/2CHCl3 is a stair-like tetramer with two central (14–Te–6)
and two peripheral (12–Te–5) Te atoms; two central Cl− ions interact with three Te atoms,
Received 3 December 2008; accepted 4 December 2008.
Dedicated to Professor Naomichi Furukawa on the occasion of his 70th birthday.
Address correspondence to Wolf-W. du Mont, Institut fuer Anorganische und Analytische Chemie, Tech-
nische Universitaet Braunschweig, Hagenring 30, 38106 Braunschweig, Germany. E-mail: w.du-mont@tu-bs.de
1243

1244
W.-W. DU MONT ET AL.
and the two peripheral Cl− ions interact with two Te atoms (the solvent is only weakly held
in the lattice). The unsolvated compound is based on dimeric units.5 The solid fluorinated
telluronium salt (C6F5)3TeCl is an unsymmetrically chloride-bridged chain polymer.7
Triphenyltelluronium iodide has been known since 1911,8 but in our hands, attempts
to complete an X-ray crystallographic structure determination were unsuccessful for a long
time; the structure, which seemed to be severely disordered, could not be satisfactorily
refined with Zꢁ = 2 in space group P1 (see the Experimental section). Preliminary results9
suggested that solid Ph3TeI adopts a tetrameric ladder-like structure, as do [Ph3TeCl]4
and [(Ph3TeI)4(MesTeI)2].10 In the latter compound, two outer iodide anions from the
[(Ph3TeI)4] unit coordinate to an MesTeI acceptor unit (Figure 1).10
The Te1-I2 distances are shorter than Te2–I2 and Te3–I2, which might justify an
alternative description of the compound as−consisting of [(Ph3Te)4I2]2+ cations that are
in contact with two triiodide-like MesTeI2 anions, thereby shar−ing the atom I2. Much
. . .
weaker cation–anion Te I interactions than those with MesTeI2 anions are present in
[(Ph3Te)2TeI6], with two Ph3Te+ cations surrounding the central TeI62− anion. Each cation
2−
. . .
exhibits three long contacts (Te1 I 3.8971(4) Å) to the regular octahedral TeI6 anion
(Te2–I 2.9456 Å) (Figure 2).10
Considering these aspects, we were keen to investigate the structural role that would
be played by triiodide anions as weak, but potentially bridging soft anions in combination
with triphenyltelluronium cations, and to determine the true structure of pure Ph3TeI.
REACTIONS
Single crystals of Ph3TeI (1) were obtained by evaporation of a methanol solution
of the compound. Addition of the equivalent amount of molecular iodine to 1 dissolved
Figure 1 Inversion-symmetric structure of [(Ph3TeI)4(MesTeI)2]10 in the crystal.

SOFT–SOFT INTERACTIONS WITH TRIPHENYLTELLURONIUM CATIONS
1245
Figure 2 Structure of [(Ph3Te)2TeI6]10 in the crystal.
Figure 3 The structure of compound 1 in the crystal. Ellipsoids represent 50% probability levels; carbon
atoms were refined isotropically. Hydrogen atoms are omitted. Te–I distances in the figure are rounded for
clarity; exact values may be taken from the following list of selected bond lengths (Å) and angles (◦):
I1–Te1 3.5081(12), I1–Te2 3.6077(15), I2–Te2 3.5697(13), I2–Te1 3.7727(15), I2–Te3 3.8730(14), I3–Te3
3.5350(14), I3–Te1 3.6531(13), I3–Te4 3.7334(13), I4–Te3 3.5189(13), I4–Te4 3.5545(14), Te1–C21 2.135(7),
Te1–C11 2.137(7), Te1–C31 2.154(6), Te2–C41 2.117(7), Te2–C51 2.122(6), Te2–C61 2.149(7), Te3–C71
2.149(7), Te3–C81 2.149(7), Te3–C91 2.135(7), Te4–C101 2.112(7), Te4–C111 2.128(7), Te4–C121 2.140(7);
Te1–I1–Te2 94.70(3), Te2–I2–Te1 90.89(3), Te2–I2–Te3 102.35(2), Te1–I2–Te3 88.23(3), Te3–I3–Te1 95.54(3),
Te3–I3–Te4 91.36(3), Te1–I3–Te4 103.41(2), Te3–I4–Te4 94.68(3), C21–Te1–C11 93.7(2), C21–Te1–C31
94.5(2), C11–Te1–C31 95.3(2), C11–Te1–I1 171.17(17), C21–Te1–I3 174.16(17), C31–Te1–I2 169.06(17),
C61–Te2–I2 176.19(18), C41–Te2–I1 170.39(17), C71–Te3–I4 177.52(17), C91–Te3–I3 171.19(17), C81–Te3–I2
167.25(16), C111–Te4–I4 171.77(18), C121–Te4–I3 171.22(18).

1246
W.-W. DU MONT ET AL.
in dichloromethane leads to a dark brown solution. When this is carefully overlayed with
n-hexane, needles of Ph3TeI3 (2) are formed. These exhibit a metallic-blue luster, but appear
dark red in transmitted light.
CRYSTALLOGRAPHIC STUDIES
Using the original data, we were able to show that compound 1 in fact crystallizes
in the triclinic space group P1 with Z = 4 (see the Experimental section), and consists of
isolated tetrameric units with a step-like central arrangement of the Te4I4 core (Figure 3);
all core angles (at tellurium and iodine) are approximately 90◦ or 180◦. The coordination
at Te1 and Te3 is [3 + 3] distorted octahedral, whereas Te2 and Te4 are [3 + 2] square
pyramidal (apices C51 and C101, respectively). Iodines I1 and I4 bridge two tellurium
. . .
centers, I2 and I3 three. There is no clear pattern to the Te I distances, which range from
3.51 to 3.87 Å.
. . .
. . .
The crystal packing involves five C H I contacts with H I < 3.3 Å and angles
around 140◦, which might be interpreted as weak hydrogen bonds. Within the tetramer,
there are a further 11 such contacts, although six of these have narrow angles < 133◦.
Details of these are given in the deposited CIF files. There are also five intermolecular
. . .
. . .
C H (ring centroid) contacts with H Centroid < 2.85 Å, but no stacking interactions.
The triiodide 2 (Figure 4) crystallizes in the monoclinic space group P21/n with Z =
4. The asymmetric unit contains one cation and one anion, and these are connected by two
. . .
Te I contacts (to I1 and I2).
The packing involves double chains of alternating anions and cations parallel to the
. . .
x axis (Figure 5). The coordination at tellurium is completed by two further Te I contacts
to I1 of a second and I3 of a third anion; all contact distances lie in the range 3.77–4.01
Figure 4 The structure of compound 2 in the crystal (asymmetric unit only). Ellipsoids represent 50% probability
levels. Selected bond lengths (Å) and angles (◦): I1–I2 2.9837(8), I2–I3 2.8472(7), I1–Te 3.7670(6), I2–Te
4.0079(6), Te–C7 2.116(4), Te–C13 2.117(4), Te–C1 2.126(4); C7–Te–C13 98.21(16), C7–Te–C1 96.30(16),
C13–Te–C1 95.43(17).

SOFT–SOFT INTERACTIONS WITH TRIPHENYLTELLURONIUM CATIONS
1247
. . .
Figure 5 Packing diagram of compound 2; part of the infinite chain parallel to the x axis. Te I contacts are indi-
. . .
. . .
. . .
cated by dashed and I I contacts by dotted lines. Distances (I–I and Te I in boldface,ꢁI I dotted) are rounded
ꢁ
. . .
. . .
. . .
for clarity; exact distances (Å) are as follows: Te I1 (–x,–y,1–z) 3.9504(6), Te I3 (1–x,–y,1–z) 3.8384(7),
ꢁ
◦
. . .
ꢁ. . .
. . .
I3 I1 (1+x,y,z) 4.3362(10), I3 I2 4.3445(7), I3 I3 4.2960(8). Selected bond angles ( ): C1–Te I1
ꢁ
ꢁ
. . .
. . .
177.40(12), C7–Te I1 162.76(11), C13–Te I3 152.36(11), I1–I2–I3 175.366(14), I(2)–I(1)–Te. 71.778(11),
I(2)-I(1)-Teꢁ (-x,-y,1-z) 106.686(15), Te-I(1)-Teꢁ 97.022(12), I2-I3-Teꢁꢁ (1-x,-y,1-z) 142.033(17). Teꢁ and Teꢁꢁ are
not labelled explicitly but lie top right and top left, respectively, in the figure.
. . .
Å. If the contact Te I2 is neglected, the geometry at tellurium is the well-known [3 + 3]
pattern with approximately octahedral geometry.
The I I distances within the anion [I1–I2 2.9837(8), I2–I3 2.8472(7) Å] reflect
. . .
the fact that I1 is involved in two Te I contacts but I3 only in one. The latter atom
. . .
additionally forms three very long (ca. 4.3 Å) I I contacts of the type that we have
described as “tertiary,”11 which may however only represent chance features of the packing
without any great energetic significance.
Whereas we attribute great importance to the soft–soft contacts in compound 2, other
types of contact should not be ignored. However, there are no stacking interactions (shortest
. . .
intercentroid distance 4.8 Å), the shortest H I distances (possibly representing weak
. . .
. . .
hydrogen bonds of the type C H I) are 3.23 Å and there is only one short H Centroid
. . .
distance [H10 Cent(C13–18) 2.72 Å].
CONCLUSION
Solid Ph3TeI (1) is a molecular tetramer, and Ph3TeI3 (2) exhibits an extended, ribbon-
like, supramolecular structure. Cation–anion soft–soft interactions in the triiodide salt 2 are
weaker, and Te C distances are slightly shorter than in the tetrameric iodide 1. As in
[(Ph3TeI)4(MesTeI)2], compared with [(Ph3Te)2TeI6],10 distortions of the Ph3Te+ cations
(by Te C bond expansion) in 1 and 2 correlate well with secondary n(I−)→σ∗(Te C)
interactions within the iodide- and triiodide-bridged structures.1,10

1248
W.-W. DU MONT ET AL.
EXPERIMENTAL
X-Ray Structure Determinations
Data were recorded using Mo-Kα radiation (λ = 0.71073 Å) on a Stoe STADI-4
diffractometer. Absorption corrections were based on ψ-scans. Structures were refined
using the program SHELXL-97 (G. M. Sheldrick, University of Go¨ttingen, Germany).
Hydrogen atoms were included using a riding model. Crystallographic data (excluding
structure factors) have been deposited with the Cambridge Crystallographic Data Centre
as supplementary publication no. CCDC-711843 (1) and CCDC-711844 (2), and can be
obtained free of charge via www.ccdc.cam.ac.uk/data request/cif.
Special Features
The iodide 1 could not be satisfactorily refined with Z’ = 2 in space group P1;
despite apparently sensible heavy atom positions, the phenyl rings were badly resolved and
appeared to be disordered. Refinement in space group P1 with Z = Z’ = 4 was therefore
attempted; a complete system of ordered rings was slowly built up and refined satisfactorily,
although there are necessarily some negative features associated with the pronounced
pseudosymmetry: (i) the Flack parameter of 0.42(2) indicates racemic twinning; (ii) carbon
atoms could only be refined isotropically; (iii) a system of restraints to local ring symmetry
was necessary to improve stability of refinement. Dimensions involving light atoms should
be interpreted with caution.
Crystal Data for 1
C18H15ITe, Mr = 485.80, triclinic, space group P1, a = 12.023(4), b = 12.309(4), c
= 12.896(4) Å, α = 66.67(2), β = 71.14(2), γ = 79.11(2)◦, V = 1654.3(9) Å3, Z = 4, ρcalc
= 1.951 Mg/m3, µ(Mo-Kα) = 3.7 mm−1, F(000) = 912, T = 133 K; orange prism 0.5 ×
0.4 × 0.3 mm3. Of 8533 reflections collected to 2θ 55◦, 8349 were independent (Rint
=
0.020). Final R1 = 0.0278 (I>2σ(I)), wR2 = 0.0682 (all data) for 363 parameters and 171
restraints; S = 1.05, max. ρ 1.17 e Å−3
.
Crystal Data for 2
C18H15I3Te, Mr = 739.60, monoclinic, space group P21/n, a = 10.021(2), b =
14.911(2), c = 13.826(2) Å, β = 95.509(10)◦, V = 2056.4(6) Å3, Z = 4, ρcalc = 2.389
Mg/m3, µ(Mo-Kα) = 5.9 mm−1, F(000) = 1336, T = 133 K; red prism 0.8 × 0.28 × 0.24
mm3. Of 3865 reflections collected to 2θ 50◦, 3607 were independent (Rint = 0.020). Final
R1 = 0.0243 (I>2σ(I)), wR2 = 0.0559 (all data) for 200 parameters; S = 1.13, max.
ρ
0.67 e Å−3
.
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p. 739; (b) A. F. Wells, Acta Cryst., 20, 610 (1966).
3. H. Fleischer and D. Schollmeyer, Acta Cryst. C, 55, 1572 (1999).

SOFT–SOFT INTERACTIONS WITH TRIPHENYLTELLURONIUM CATIONS
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