Structural trends in TeI2RR′: Crystal structures and NMR spectra of TeI2(CH2SiMe3)2, TeI 2Th(CH2SiMe3), TeI2Ph(CH 2SiMe3), and TeI<sub

Article abstract of DOI:10.1002/hc.20688

TeI₂(CH₂SiMe₃)₂(1), TeI ₂Th(CH₂SiMe₃ (2), TeI₂Ph(CH ₂SiMe₃)(3), and TeI₂Th₂(4) (Th = 2-thienyl) were synthesized in excelle

Full text of DOI:10.1002/hc.20688

Heteroatom Chemistry
Volume 22, Number 3/4, 2011
ꢀ
Structural Trends in TeI RR : Crystal
2
Structures and NMR Spectra of
TeI (CH SiMe ) , TeI Th(CH SiMe ),
2
2
3 2
2
2
3
TeI Ph(CH SiMe ), and TeI Th
2
2
3
2 2
(Th = 2-Thienyl, C H S)
4 3
Merja J. Poropudas, Ludmila Vigo, Raija Oilunkaniemi,
and Risto S. Laitinen
Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu, Oulu, Finland
Received 29 September 2010; revised 7 November 2010
with TeI2Th(CH2SiMe3)(2). The other (3b) shows a
ABSTRACT: TeI2(CH2SiMe3)2 (1), TeI2Th(CH2SiMe3
(2), TeI2Ph(CH2SiMe3) (3), and TeI2Th2(4) (Th = 2-
thienyl) were synthesized in excellent yields from the
corresponding tellanes and I2. The products were char-
acterized by 125Te NMR spectroscopy and single crystal
X-ray crystallography. Each TeI2RRꢀ molecule shows
a trigonal bipyramidal coordination around tellurium
with the iodine atoms occupying axial positions, and
the organic groups and the lone pair occupying equa-
torial positions. The Te I bonds and the I Te I an-
lattice of two alternating layers of molecules. In one
layer, the molecules are linked into a two-dimensional
network by Te···I and I···I interactions whereas the
second layer consists of discrete dimers. The strongest
Te···I secondary bonding interactions are observed for
TeI2Th2. The lattice is composed of tetramers that is
reminiscent of those in γ - and δ-TeI4 and also have
precedent in TeI2RRꢀ species. The structures of TeI2Me2
and TeI2Ph2 have been considered for comparison. The
trends in 125Te NMR chemical shifts in TeI2RRꢀ(R,
˚
gles in 1–4 span a range of 2.8407(9)–3.0194(10) A
ꢀ
ꢁ
C
R = Me, CH2SiMe3, Th, Ph) are also discussed. 2011
and 171.85(2)–175.71(2)◦, respectively. The Te C
Wiley Periodicals, Inc. Heteroatom Chem 22:348–357,
2011; View this article online at wileyonlinelibrary.com.
DOI 10.1002/hc.20688
bonds and C Te C angles show respective ranges
◦
˚
of 2.100(6)–2.136(7) A and 95.1(3)–100.9(3) . In the
solid state, the molecules show a varying degree of
secondary bonding interactions. With the exception
of TeI2(CH2SiMe3)2(1), the compounds show Te···I
or I···I secondary bonding interactions leading to
supramolecular assemblies. TeI2Ph(CH2SiMe3) crys-
tallizes as two polymorphs. One (3a) is isomorphic
INTRODUCTION
Diorganyltellanes react with iodine to afford di-
iododiorganyltellurium(IV), TeI2RRꢀ [1,2]. In these
molecules, the primary bonding environment of tel-
lurium is a distorted trigonal bipyramid in which the
organic groups and the lone-pair of tellurium occupy
the equatorial positions whereas the iodine atoms lie
at the axial positions (for selected molecular species
(see [3–14]). In the solid state, TeI2R2 molecules
generally show intermolecular Te···I or I···I sec-
ondary bonding interactions (the concept of which
Dedicated to Professor Kin-ya Akiba on the occasion of his 75th
birthday.
Correspondence
to:
R.
Oilunkaniemi;
e-mail:
raija
.oilunkaniemi@oulu.fi, Risto S. Laitinen; e-mail: risto.laitinen@
oulu.fi.
Contract grant sponsor: Academy of Finland.
Contract grant sponsor: Ministry of Education.
2011 Wiley Periodicals, Inc.
c
ꢀ
348

Structural Trends in TeI2RRꢀ 349
13C and 125Te spectral widths were 24.04 and 126.58
kHz, respectively, the pulse widths 10.00 μs, and the
pulse delays were 1.60 s. In both cases, 13C accu-
mulations typically contained ca. 1,000 transients
and 125Te accumulations ca. 30,000 transients. All
spectra were recorded unlocked. A saturated solu-
tion of diphenylditellane in CDCl3 was used as an
external standard for 125Te. Chemical shifts (ppm)
are reported relative to neat Me2Te [δ (Me2Te) = δ
(Ph2Te2) + 422] [21].
was originally introduced by Alcock [15]) that gen-
erally expand the AX4E (X = bonding pair, E = lone
pair) trigonal pyramidal geometry around tellurium
into five- or six-coordinate AX4YE or AX4Y2E (X =
primary bond, Y = secondary bond) environments
and lead to the formation of supramolecular frame-
works [3]. These frameworks can typically be chains,
layers, or three-dimensional networks. Depending
on the nature of the organic groups, other inter-
molecular interactions can contribute to the forma-
tion of supramolecular assemblies [16].
In the present work, we have explored effect
of the nature of the organic groups on solid-
state structures of TeI2RRꢀ. We report the prepa-
ration of TeI2(CH2SiMe3)2 (1), TeI2Th(CH2SiMe3)
(2), TeI2Ph(CH2SiMe3) (3), and TeI2Th2 (4) (Th =
2-thienyl, C4H3S) by the reaction of corresponding
diorganyltellanes with I2. The products were charac-
terized by 125Te NMR spectroscopy and single crystal
X-ray crystallography. For comparison, the struc-
tures and 125Te NMR spectroscopic properties of
TeI2Me2, TeI2PhMe, and TeI2Ph2 are also discussed
as appropriate.
X-Ray Crystallography
Diffraction data of 1–4 were collected at 120 K
on a Bruker Nonius Kappa-CCD diffractometer
using graphite monochromated Mo Kα radiation
˚
(λ = 0.71073 A; 55 kV, 25 mA). Crystallographic
data and details of crystal structure determinations
are given in Table 1. The structures were solved
by direct methods using SIR-92 [22], and refined
using SHELXL-97 [23]. After the full-matrix least-
squares refinement of the non-hydrogen atoms with
anisotropic thermal parameters, the hydrogen atoms
were placed in calculated positions in the aromatic
˚
˚
rings (C H = 0.95 A), in CH3 groups (C H = 0.98 A),
EXPERIMENTAL
General
˚
and in CH2 groups (C H = 0.99 A). In the final re-
finement, the calculated hydrogen atoms were rid-
ing with the carbon atom they were bonded to. The
isotropic thermal parameters of the hydrogen atoms
were fixed at 1.2 times to that of the corresponding
carbon atom in the aromatic rings and to 1.5 times to
that in methyl or methylene groups. The scattering
factors for the neutral atoms were those incorpo-
rated with the programs.
All reactions were carried out under an ar-
gon atmosphere. Diethylether (Lab-Scan, Gliwice,
Poland), n-hexane (Lab-Scan), dichloromethane
(Lab-Scan), and iodine (Aldrich, Schnelldorf,
Germany) were commercially available and were
used without further purification. Tetrahydrofu-
ran (Lab-Scan) was dried and distillated over
Na/benzophenone under an argon atmosphere prior
to use. Te(CH2SiMe3)2 was prepared according to
the literature method [17]. TeTh2 was prepared
from Te2Th2 [18] by copper(0)-promoted detellu-
ration [19]. TeTh(CH2SiMe3) and TePh(CH2SiMe3)
were prepared from bis(2-dithienyl) ditellane and
diphenyl ditellane, respectively, by using the method
described by Ogura et al. [20]. The NMR spec-
troscopic data of the tellanes (CDCl3, 25◦C, ppm):
The thienyl rings C4H3S in 4 were found to be
disordered. The disorder was refined by constraining
the sum of the site occupation factors of each disor-
dered pair to unity. Since the site occupation factors
and thermal parameters of the disordered atoms cor-
relate with each other, the thermal parameters of the
corresponding pairs of atoms were restrained to be
equal. The positional parameters of the disordered
pairs of atoms were also constrained to be equal.
Crystallographic information of 1–4 has been
deposited with the Cambridge Crystallographic
Data Center as supplementary publication num-
bers CCDC 794943–794947. Copies of the data
can be obtained free of charge on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK [Fax: int. code + 44(1223)336-033; e-mail:
deposit@ccdc.cam.ac.uk].
1
Te(CH2SiMe3)2: δ 13C{ H} 15.8 (CH2), –3.5 (SiMe3);
1
125Te 26. TeTh(CH2SiMe3): δ 13C{ H} 140.6, 133.8,
128.8, 98.7 (C4H3S), –0.4 (SiMe3), –5.1 (CH2); 125Te
1
234. TePh(CH2SiMe3): δ13C{ H}: 137.0, 129.2, 127.3,
113.2 (C6H5), −0.3 (SiMe3), –8.8 (CH2); 125Te 344.
1
TeTh2: δ13C{ H}: 140.9, 134.6, 129.0 103.0 (C6H5);
125Te 408.
NMR Spectroscopy
Preparation of TeI2(CH2SiMe3)2(1)
125Te NMR spectra were recorded on a Bruker
DPX400 spectrometer operating at 126.28 MHz. The
Bis(trimethylsilylmethyl)tellane (0.094 g; 0.311
mmol) was dissolved in 3 mL of THF, and the
Heteroatom Chemistry DOI 10.1002/hc

350 Poropudas et al.
TABLE 1 Details of the Structure Determination of TeI2(CH2SiMe3)2 (1), TeI2Th(CH2SiMe3) (2), TeI2Ph(CH2SiMe3) (3a and
3b), and TeI2Th2 (4) (Th = thienyl, C4H3S)
1
2
3a
3b
4
Empirical formula
Formula weight
Crystal system
Space group
C8H22I2Si2Te
555.84
Triclinic
¯
P1
C8H14I2SSiTe
551.74
Triclinic
¯
P1
C10H16I2SiTe
545.72
Triclinic
¯
P1
C10H16I2SiTe
545.72
Monoclinic
C2/c
C8H6S2I2Te
547.65
Triclinic
¯
P1
˚
a (A)
7.2326(14)
9.870(2)
12.813(3)
106.96(3)
94.41(3)
92.25(3)
7.9645(16)
9.6148(19)
10.651(2)
78.66(3)
68.34(3)
86.59(3)
8.0401(16)
9.6010(19)
10.862(2)
79.09(3)
69.11(3)
85.54(3)
38.914(8)
6.9889(14)
24.514(5)
9.4543(19)
11.688(2)
12.698(3)
86.44(3)
68.61(3)
74.89(3)
˚
b (A)
˚
c (A)
α (◦)
β (◦)
γ (◦)
108.46(3)
3
˚
V (A )
870.5(3)
2
743.2(3)
2
769.2(3)
2
6324(2)
16
1260.5(4)
4
Z
F(000)
512
2.121
5.364
500
2.466
6.341
496
2.356
5.995
3968
2.293
5.833
976
2.886
7.546
Dcalc. (g cm−3
)
μ (Mo Kα) (mm−1
)
Crystal size (mm)
0.50 × 0.50 ×
0.10 × 0.10 ×
0.20 × 0.20 ×
0.20 × 0.10 ×
0.20 × 0.10 ×
0.10
0.09
0.15
0.05
0.08
ꢀ range (◦)
Reflections collected
Unique reflections
1.67–26.00
13573
3376
3.28–25.99
12372
2892
2.04–25.99
10852
2972
3.04–26.00
23110
6209
3.35–25.99
18586
4894
Observed reflections
Parameters/restraints
2745
124/0
2444
122/0
1.031
2553
130/0
1.124
4669
259/0
1.031
4267
240/40
1.093
Goodness-of-fit on F2 1.093
Rint
0.0694
0.0546
0.1366
0.0680
0.1577
0.0665
0.0387
0.0994
0.0492
0.1067
0.0969
0.0623
0.1753
0.0733
0.1927
0.0803
0.0418
0.0934
0.0674
0.1060
0.0841
0.0503
0.1287
0.0577
0.1349
a,b
R1
wRa2,b
R1 (all data)b
wR2 (all data)b
aI ≥ 2σ(I ).
bR1 = ꢁ|| Fo| − |Fc||/ꢁ|Fo|, wR2 = [ꢁw(Fo2–Fc2)2/ꢁwFo.
resulting solution was added dropwise into a solu-
tion of iodine (0.080 g; 0.315 mmol) in 3 mL of
THF. The reaction mixture was stirred for 2 h at
room temperature and then sequentially concen-
trated by evaporation of the solvent. The reaction
product was precipitated by adding a few drops of
cold n-hexane to the cooled concentrated solution.
The crude product was filtered, washed with cold n-
hexane, and recrystallized from diethyl ether, giving
orange crystals of 1 (yield 91%, 0.157 g). Anal. Calcd.
for TeI2Si2C8H22; C 17.29, H 3.99; found C 17.25, H
0.161 g). Anal. Calcd. for TeI2SiSC8H14; C 17.42,
H 2.56; found C 17.69, H 2.60. NMR (CDCl3,
1
25◦C, ppm): δ13C{ H}: 140.4, 134.8, 128.1, 109.2
(C6H5), 32.9 (CH2), –0.8 (SiMe3); 125Te 729.
Preparation of TeI2Ph(CH2SiMe3) (3)
Phenyl(trimethylsilylmethyl)tellane (0.095 g; 0.325
mmol), I2 (0.081 g; 0.319 mmol). Recrystallization
from CH2Cl2 yielded dark red crystals of 3a and or-
ange crystals of 3b (combined yield 99%, 0.173 g).
Anal. Calcd. for TeI2SiC10H16; C 22.01, H 2.96; found
1
3.99. NMR (CDCl3, 25◦C, ppm): δ13C{ H} 26.2 (CH2),
1.3 (SiMe3); 125Te 655.
The following reactions were performed in a
similar fashion.
1
C 22.75, H 3.04. NMR (CDCl3, 25◦C, ppm): δ13C{ H}:
134.4, 131.6, 130.6, 124.9 (C6H5), 28.4 (CH2), 1.7
(SiMe3); 125Te 690.
Preparation of TeI2Th(CH2SiMe3) (2)
Preparation of TeI2Th2(4)
Thienyl(trimethylsilylmethyl)tellane (0.097 g; 0.326
mmol), I2 (0.085 g; 0.335 mmol). Dark orange crys-
tals of 2 were obtained from CH2Cl2 (yield 90%,
Bis(2-thienyl)tellane (0.098 g; 0.335 mmol), I2 (0.091
g; 0.358 mmol). Recrystallization from THF yielded
Heteroatom Chemistry DOI 10.1002/hc

Structural Trends in TeI2RRꢀ 351
dark red crystals of 4 (yield 94%, 0.173 g). Anal.
Calcd. for TeI2S2C8H6; C 17.54, H 1.10; found C
1
17.96, H 1.14. NMR (CDCl3, 25◦C, ppm): δ13C{ H}:
141.2, 135.2, 128.1, 118.2 (C4H3S); 125Te 892.
RESULTS AND DISCUSSION
General
The reactions of diorganyl tellanes Te(CH2SiMe3)2,
TeTh(CH2SiMe3), TePh(CH2SiMe3), and TeTh2 with
iodine afford the corresponding diiodidoorganyl-
tellurium(IV) 1–4 in excellent yields. The products
are relatively stable in air at room temperature.
The choice of the solvent for recrystallization to
obtain pure crystalline products was dependent on
the organic group. Diiodidobis(trimethylsilymethyl)
tellurium(IV) (1) was recrystallized from di-
ethylether,
diiodidothienyl(trimethylsilylmethyl)
tellurium(IV) (2), diiodidophenyl(trimethylsilyl-
methyl)-tellurium(IV) (3) from dichloromethane,
and diiodidobis(2-thienyl)tellurium(IV) (4) was
recrystallized from tetrahydrofuran. Upon recrys-
tallization of 3, two crops of crystals were obtained:
dark red crystals 3a and orange crystals 3b.
FIGURE 1 (a) The molecular structure of TeI2(CH2SiMe3)2
(1) indicating the numbering of atoms. The thermal ellip-
soids have been drawn at 50% probability level. Selected
Crystal Structures
The molecular structures of 1–4 indicating the num-
bering of the atoms and selected bond distances and
angles are shown in Figs. 1–3.
◦
˚
bond distances (A) and angles ( ): Te1–I1 2.8904(10), Te1–
I2 2.9487(10) Te1–C1 2.129(6), Te1–C2 2.132(7), I1–Te1–I2
175.34(2), I1–Te1–C1 88.3(2), I1–Te1–C2 91.0(2), I2–Te1–
C1 86.9(2), I2–Te1–C2 89.5(2), C1–Te1–C2 99.9(3). (b) The
molecular structure of TeI2Th(CH2SiMe3) (2) indicating the
numbering of atoms. The thermal ellipsoids have been drawn
The coordination environment around the tel-
lurium in each compound is expectedly a pseudotrig-
onal bipyramid with the tellurium lone-pair and the
two bonding pairs involving organic groups occupy-
ing equatorial positions. Iodine atoms are found in
the axial positions. The stereochemical activity of the
lone pair of the tellurium atoms results in the axial
iodine atoms to lean away from the lone pair reduc-
ing the I Te I bond angles from the ideal value of
180◦. The C Te C bond angles are also smaller than
the ideal 120◦.
˚
at the 50% probability level. Selected bond distances (A)
and angles (◦): Te1–I1 2.9512(8), Te1–I2 2.9098(8) Te1–C1
2.136(7), Te1–C21 2.100(6), I1–Te1–I2 172.24(2), I1–Te1–
C1 87.6(2), I1–Te1–C21 94.2(2), I2–Te1–C1 89.7(2), I2–Te1–
C21 93.3(2), C1–Te1–C21 95.3(2).
strong influence on the bond lengths and the for-
mation of supramolecular assemblies [3–14].
The axial Te I bond lengths [2.8904(10) and
˚
˚
2.9487(10) A in 1, 2.9098(8) and 2.9512(8) A in
The Te···I and I···I secondary bonding interac-
tions in 1–4, TeI2Me2 [14, 25], and TeI2Ph2 [26] are
summarized in Table 2. It can be seen that Te···I close
contacts are more common than I···I close contacts.
This seems to be a general feature in all TeI2RRꢀ
[3–14]. McCullough et al. [27] have correlated the
presence of I···I secondary bonds with the color of
the crystalline material. In the absence of I···I close
contacts, the crystals appear orange or bright red.
With increasing influence of the I···I interactions, the
color becomes deeper red and tends toward purple
and black. The colors of the present compounds are
˚
2, 2.9266(9) and 2.9288(10) A in 3a, 2.8992(8)–
˚
˚
2.9309(8) A in 3b, and 2.8407(9)–3.0194(10) A in 4]
are expectedly longer than single bonds (the sum of
the covalent radii of tellurium and iodine is 2.70 A
˚
[24]). It has previously been reported that the I Te I
moiety is often asymmetric, the shorter bonds rang-
˚
˚
ing 2.85–2.90 A and the longer bonds 2.91–3.01 A
[25,26]. The variation in the Te I bond lengths are
normally correlated with the I···Te and I···I sec-
ondary bonding, but hydrogen bonds and other pos-
sible secondary bonding interactions also have a
Heteroatom Chemistry DOI 10.1002/hc

352 Poropudas et al.
FIGURE 3 The molecular structure of TeI2Th2 (4) indicat-
ing the numbering of atoms. The thermal ellipsoids have
been drawn at the 50% probability level. The symmetry-
equivalent tellurium and iodine atoms have been de-
noted by a superscript a (symmetry operation 1-x, 1-y,
1-z). The symmetry-equivalent carbon and sulfur atoms
have not been denoted in the figure. Selected bond dis-
tances (A) and angles ( ): Te1–I11 2.8407(9), Te1–I12
3.0194(10), Te2–I21 2.9319(10), Te2–I22 2.9332(10), Te1–
C11A 2.118(8), Te1–C15A 2.118(8), Te2–C21A 2.110(7),
Te2–C25A 2.102(8), I11–Te1–I12 171.85(2), I11–Te1–C11A
93.6(2), I11–Te1–C15A 92.6(2), I12–Te1–C11A 91.8(2), I12–
Te1–C15A 93.0(2), C11A–Te1–C15A 95.1(3), I21–Te2–I22
175.71(2), I21–Te2–C21A 92.4(2), I21–Te2–C25A 90.9(2),
I22–Te2–C21A 89.7(2), I22–Te2–C25A 92.6(2), C21A–Te2-
C25A 95.4(3) (The bond parameters of only the most abun-
dant orientations of the disordered thienyl rings are consid-
ered here).
FIGURE 2 (a) The molecular structure of TeI2Ph(CH2SiMe3)
(3a) indicating the numbering of atoms. The thermal ellip-
◦
˚
soids have been drawn at the 50% probability level. Selected
◦
˚
bond distances (A) and angles ( ): Te1–I1 2.9288(10), Te1–
I2 2.9266(9) Te1–C1 2.135(8), Te1–C21 2.126(8), I1–Te1–
I2 172.69(3), I1–Te1–C1 88.8(2), I1–Te1–C21 93.3(2), I2–
Te1–C1 88.3(2), I2-Te1–C21 93.7(2), C1–Te1–C21 96.1(3).
(b) The molecular structure of TeI2Ph(CH2SiMe3) (3b) in-
dicating the numbering of atoms. The thermal ellipsoids
have been drawn at the 50% ◦probability level. Selected
˚
bond distances (A) and angles ( ): Te1–I11 2.9309(8), Te1–
I12 2.8992(8), Te2–I21 2.9020(8), Te2–I22 2.9293(8), Te1–
C1 2.135(7), Te1–C14 2.127(6), Te2–C2 2.124(6), Te2–C24
2.119(7), I11–Te1–I12 174.40(2), I11–Te1–C1 87.4(2), I11–
Te1–C14 88.0(2), I12–Te1–C1 88.5(2), I12–Te1–C14 89.0(2),
C1–Te1–C14 100.9(3), I21–Te2–I22 174.01(2), I21–Te2–C2
87.1(2), I21–Te2–C24 88.6(2), I22–Te2–C2 88.3(2), I22–Te2–
C24 88.3(2), C2–Te2–C24 99.4(3).
for a number of related species (typical examples
are shown in [3–14] and [25,26]). The molecules are
packed into skewed stacks (Fig. 4) that are linked by
˚
weak I···H hydrogen bonds of 3.250(1)–3.284(1) A.
TeI2Th(CH2SiMe3) (2) and one polymorph of
TeI2Ph(CH2SiMe3) (3a) are isomorphic as indicated
in Fig. 5. They both show relatively strong I···I in-
teractions, but only 2 exhibits appreciable Te···I in-
teraction (see Table 2). Furthermore, the lattices of
both 2 and 3a exhibit three-dimensional H···I hydro-
gen bonding network. The H···I close contacts are
mainly consistent with this scheme; we note that 4 is
deep red, although there are no I···I secondary bond-
ing interactions in the lattice.
TeI2(CH2SiMe3)2 (1) shows hardly any secondary
bonding interactions (see Table 2). The shortest re-
spective Te···I and I···I intermolecular contacts in 1
are only slightly shorter than the sum of the van der
Waals radii of the relevant atoms but significantly
longer than those of 2–4 and the values reported
˚
3.2125(9) and 3.216(1)–3.268(1) A for 2 and 3a, re-
spectively.
Heteroatom Chemistry DOI 10.1002/hc

Structural Trends in TeI2RRꢀ 353
˚
TABLE 2 Intermolecular Te···I and I···I Contacts (A) in 1–4, TeI2Me2 and TeI2Ph2 That Are Shorter Than the van der Waals’
Radii of the Relevant Atoms
Te I
Te···I
I···I
Reference
TeI2Me2
Polymorph 1
mol 1
2.885(3)
2.965(3)
2.914(3)
2.934(3)
2.854(3)
2.994(3)
2.9159(9)
2.8904(10)
2.9487(10)
2.9098(8)
2.9512(8)
3.919(3)
3.659(3)
3.912(3)
3.826(3)
3.907(3)
4.030(3)
3.7383(9)
4.229(1)
–
–
–
–
–
–
–
–
[25]
[14]
mol 2
mol 3
Polymorph 2
TeI2(CH2SiMe3)2 (1)
4.185(1), 4.246(1)
This work
This work
This work
–
–
TeI2Th(CH2SiMe3) (2)
–
3.895(1)
3.7991(8), 4.280(1)
TeI2Ph(CH2SiMe3)
Polymorph 1 (3a)
2.9266(9)
2.9288(10)
4.108(2)
–
3.804(2)
3.804(2)
Polymorph 2 (3b)
mol 1
2.8992(8)
2.9309(8)
2.9020(8)
2.9293(8)
4.009(1)
4.1526(7)
–
3.7503(5)
4.1187(7)
–
–
mol 2
3.929(1)
TeI2Th2 (4)
mol 1
2.8407(9)
3.0194(10)
2.9319(10)
2.9332(10)
–
–
–
–
–
–
–
This work
[26]
3.646(1), 3.660(1)
3.646(1)
mol 2
3.659(1)
TeI2Ph2
Polymorph 1
Polymorph 2
mol 1
2.928(1)
3.955(1)
2.893(1)
2.959(1)
2.883(1)
2.942(1)
3.926(1)
–
3.850(1)
3.924(1)
–
–
–
–
mol 2
FIGURE 4 Packing of molecules in 1. Hydrogen atoms have been omitted for clarity.
Heteroatom Chemistry DOI 10.1002/hc

354 Poropudas et al.
FIGURE 5 Packing of molecules in 2. (b) Packing of molecules in 3a. Hydrogen atoms have been omitted for clarity.
The lattice of second polymorph of TeI2Ph
(CH2SiMe3), 3b, is rather interesting (Fig. 6). It is
composed of two alternating layers of molecules.
In one type of layer, the molecules form a contin-
uous quasi-two-dimensional layer by both Te···I and
I···I interactions (see Table 2). In the second type of
layer, the molecules are linked into discrete dimers
by somewhat weaker Te···I interactions.
clearest in the case of 4. The iodine atom I11 shows
no secondary interactions and the Te1–I11 is only
˚
2.8407(9) A. The atoms I21 and I22 are involved in
one Te···I interaction with the Te1–I21 and Te1–I22
˚
bond lengths of 2.9319(10) and 2.9332(10) A, respec-
tively. I22 shows two Te···I close contacts and the
Te1–I12 is the longest tellurium–iodine bond in the
˚
molecule with the length of 3.0194(10) A. A similar
The Te···I secondary bonds in TeI2Th2 (4) are the
strongest in all molecular species considered in this
work (see Table 2), and the molecules are linked into
discrete tetramers, which show approximate cubic
close packing in the lattice (see Fig. 7). There are
no I···I secondary bonding interactions in 4. Simi-
lar tetrameric Te I frameworks are also observed in
TeI2(p-C6H4OMe)2 [28] and in γ -TeI4 [29, 30] and
δ-TeI4 [31, 32]. The tetramers of 4 are linked by H···I
trend in the Te I bond lengths is also observed for
TeI2(p-C6H4OMe)2 [28].
The dependence of the Te I bond lengths on the
Te···I and I···I interactions in the case of other molec-
ular species listed in Table 2 is not as clear, although
in a qualitative sense the same trend can be inferred.
Alcock and Harrison [26] have discussed the length-
ening of the Te I bond due to the secondary bond-
ing interactions in terms of the donation of either
the tellurium or iodine lone-pair to the σ* orbital
of the Te I bond. Chan and Einstein [25] have sug-
gested that the lengthening of the Te I bond due
to secondary bonding interactions increases the or-
bital overlap of tellurium and the iodine atom in the
trans-position thereby shortening the opposite Te I
bond.
˚
hydrogen bonds of 2.9798(7)–3.3043(8) A.
Both polymorphs in TeMe2I2 and TeI2Ph2 also
show only Te···I interactions. These close contacts
˚
span a range of 3.659(3)–4.030(3) A (see Table 2).
The consequent supramolecular assemblies are com-
posed of three-dimensional networks.
The influence of the secondary bonding interac-
tions on the Te I bond lengths can clearly be seen in
the data presented in Table 2. The correlation is the
The Te C bond lengths in 1–4 span a range of
˚
2.100(6)–2.136(7) A, and are quite close to single
Heteroatom Chemistry DOI 10.1002/hc

Structural Trends in TeI2RRꢀ 355
FIGURE 6 Packing of molecules in 3b. Hydrogen atoms have been omitted for clarity.
FIGURE 7 Packing of molecules in 4. Hydrogen atoms have been omitted for clarity.
Heteroatom Chemistry DOI 10.1002/hc

356 Poropudas et al.
magnetic shielding in tellurium (see, for instance,
[38, 39], and references therein) that is also depen-
dent both on the nature of the organic groups bound
to the Te(IV) center and the secondary bonding in-
teractions involving iodine.
ACKNOWLEDGMENTS
We are grateful to P. Salin for assistance in the
preparative work.
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FIGURE 8 Dependence of the 125Te chemical shifts of
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˚
lurium and carbon is 2.14 A [24]). They also fit well in
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two relatively electronegative iodine atoms bound
to tellurium, their 125Te chemical shifts are expect-
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corresponding tellanes, but the dependence of the
chemical shift on the electronegativities of the or-
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The paramagnetic contribution to the shielding at
125Te nucleus plays a significant role, which is af-
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[n(Te)→σ*(Te-I)] (for the discussion of the para-
Heteroatom Chemistry DOI 10.1002/hc

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