Bis(4-pyridyl)ditelluride as starting material for the synthesis of zwitterionic compounds and metal complexes

Article abstract of DOI:10.1016/j.jorganchem.2012.09.007

The properties of the derivatives of RTeTeR (R = alkyl, aryl) compounds are highly dependent of the R substituent. To show how versatile are the derivatives of RTeTeR with specific R groups - in this case we use Py* = p-(C₅H₄N), we studied the reactions of Te₂Py2 with HCl, CH₃I, CH₃I/I₂, I₂/(Ph ₃Te)I and CoCl₂·6H₂O, which generate the formation of many classes of compounds: zwitterions [(HPy*)TeCl ₂] (1), [(MePy*)TeI₂] (2), [(MePy*)TeI ₄] (3); a telluronium-tellurolate complex (Ph₃Te) [Py*TeI₄] (4) and a coordination polymer {_Co(Te ₂Py2)₂Cl₂]·(Te₂Py2)} _n (5). These compounds were characterized by single crystal X-ray diffraction, elemental analysis and infrared spectroscopy.

Full text of DOI:10.1016/j.jorganchem.2012.09.007

Journal of Organometallic Chemistry 723 (2013) 115e121
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Bis(4-pyridyl)ditelluride as starting material for the synthesis of zwitterionic
compounds and metal complexes
,
Sailer S. dos Santos a, Bruno N. Cabral b, Ulrich Abram c, Ernesto S. Lang b
*
a Departamento de Ciências Exatas e Tecnológicas, Universidade Estadual de Santa Cruz, 45662-900 Ilhéus, BA, Brazil
b Departamento de Química, Laboratório de Materiais Inorgânicos, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil
c Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34-36, 14195 Berlin, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
The properties of the derivatives of RTeTeR (R ¼ alkyl, aryl) compounds are highly dependent of the R
substituent. To show how versatile are the derivatives of RTeTeR with specific R groups e in this case we
use Py* ¼ p-(C5H4N), we studied the reactions of Te2Py*2 with HCl, CH3I, CH3I/I2, I2/(Ph3Te)I and
CoCl2$6H2O, which generate the formation of many classes of compounds: zwitterions [(HPy*)TeCl2] (1),
[(MePy*)TeI2] (2), [(MePy*)TeI4] (3); a telluroniumetellurolate complex (Ph3Te)[Py*TeI4] (4) and a coor-
dination polymer f½CoðTe2Py*2Þ2Cl2ꢀ$ðTe2Py2* Þgn (5). These compounds were characterized by single
crystal X-ray diffraction, elemental analysis and infrared spectroscopy.
Received 19 June 2012
Received in revised form
13 September 2012
Accepted 14 September 2012
Keywords:
Tellurium
Zwitterion
Ó 2012 Elsevier B.V. All rights reserved.
Organotellurium halides
4,40-Ditellurobispyridine
1. Introduction
species with butadienes or triphenylphosphane, and the regener-
ation of the tellurenyl cation species by thermal retro [1 þ 4]
RTeTeR compounds have been shown to be suitable starting
materials for the synthesis of a variety of tellurium compounds
containing the chalcogen in different oxidation states [1e6],
including mixed-valence aryltellurenyl compounds [7,8] and related
charge-transfer complexes [8e12]. Recently, we could demonstrate
that the substituent R (R ¼ phenyl, 2,6-dimethoxyphenyl, mesityl,
2,3,5,6-tetramethylphenyl) has a considerable influence on the
stabilization of tellurium halides with different oxidation states
[13e18]. Particularly, the influence of the substituent R on the
controlled oxidation of the tellurium atom demonstrates that the
aryltellurenyl halides can be regarded as key compounds in the
synthesis of TeI, TeII, TeIII and TeIV products [2,7,9,16,18].
cycloaddition of the diene adducts.
The crystal structures of organotellurium halide compounds
with general formula R3TeX (R ¼ alkyl, aryl; X ¼ Cl, Br, I) confirm
that the compounds are essentially ionic [20e22]. Within the
crystals, the packing is determined by Te/X secondary bonds
between anioneanion and cationeanion pairs. The primary coor-
dination geometries of the tellurenyl cations are themselves very
interesting owing to the occurrence of secondary telluriume
halogen bonds (Te/X), which create exceptional supramolecular
structures, leading the formation of polymeric chains, dimeric
structures, or monomers with fairly strong intermolecular inter-
actions. The structure and bonding of Ph3Teþ cation with relatively
large counterions hexachloro-platinate [PtCl6]2ꢁ and -iridate
[IrCl6]2ꢁ as well as square planar [AuCl4]ꢁ and [PtCl4]2ꢁ [22] and
also TeIV anionic species [TeX6]2ꢁ and [PhTeX4]ꢁ [3,4] have shown
that the cationeanion interactions are significant in governing the
coordination geometry around tellurium and the overall structural
features.
The halogenation reactions of Bbt-substituted ditelluride,
BbtTeTeBbt, leading to the formation of the TeIIeTeIV mixed-valent
tellurenyl fluoride, BbtTeTe(F)2Bbt, and tellurenyl halides, BbtTeX
(Bbt
¼
2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)
methyl]-phenyl; X ¼ Cl, Br, I) [19]. During the dehalogen-cation
reactions of these tellurium halides, it is rational to postulate the
formation of a tellurenyl cation species as an intermediate. In this
case, it was reported the successful trapping of tellurenyl cation
In the most cases, the function of the aryl group is limited to the
stabilization of the oxidation state of the tellurium atom or to
provide an additional donor atom in ortho-position for chelate
formation [11,23]. With the aim to extend the applicability of the
diorganylditellurides we selected the p-pyridyl group -Py* ¼ p-
(C5H4N) e for further studies.
* Corresponding author. Tel.: þ55 5532208980; fax: þ55 5532208031.
E-mail addresses: eslang@ufsm.br, eslang@quimica.ufsm.br (E.S. Lang).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.09.007

116
S.S. dos Santos et al. / Journal of Organometallic Chemistry 723 (2013) 115e121
The compound 4,40-ditellurobispyridine, Py*TeTePy* or Te2Py*2,
results in the formation of the zwitterions [(HPy*)TeCl2] (1),
[(MePy*)TeI2] (2) and [(MePy*)TeI4] (3); a telluroniumetellurolate
is known since 1993, when von Nagy-Felsobuki and co-workers
developed a systematic methodology for the synthesis of telluro-
and ditelluro-bispyridines [24]. More recently, Bhasin and co-
workers published a one-pot synthetic approach to various pyr-
idyl ditellurides and the X-ray crystal structures of several repre-
sentatives [25]. The use of synthons containing a pyridyl subunit
attached to a chalcogen atom is a very interesting strategy for
coordination chemistry owing the different nature of the existent
binding sites. In this sense, it is possible to extend our work to the
concept of hardness/softness in order to stabilize different inter-
actions with the same synthon. The “soft” chalcogen donor may
contribute to the formation of complexes with large Lewis acids
and the borderline pyridinic N donor may stabilize the interaction
with smaller and harder acceptors [24e30]. Despite of these very
interesting characteristics, just a few examples of such compounds
are known. This fact can be related with the difficulty to generate
such compounds directly from the corresponding halides in good
yields [25]. In the last 20 years, we could observe an increasing
interest in this kind of ligands, and the most common complexes
found in the literature were prepared from the 2-telluro deriva-
tives. It forces the formation of a chelate ring and consequently only
saturated complexes have been prepared [26e29]. The advantage
of using the 4,40-derivatives resides in the distance between the
two different coordination sites: in this case, the donor atoms are
far enough to interact with different centers and it may provide the
formation of inner (zwitterions) and outer salts as well as hetero-
metallic complexes or coordination polymers. The only example
found in the literature related to the latter topic has been published
by Ok-Sang and co-workers [30]. The authors describe a reaction of
[Co2(CO)8] with 3,6-di-t-butyl-1.2-benzoquinone, which was
carried out in the presence of 4,40-ditelluridobispyridine and
results in a polymer, which was insoluble in organic solvents.
In the course of our ongoing studies to explore the potential of
diorganylditellurium compounds as synthons, we present in this
article a series of reactions of 4,40-ditelluridobispyridine, which
complex (Ph3Te)[Py*TeI4] (4) and
a coordination polymer
f½CoðTe2Py*2Þ2Cl2ꢀ$ðTe2Py2* Þgn (5). The novel compounds were
characterized by single crystal X-ray diffraction, elemental analysis
and infrared spectroscopy.
2. Results and discussion
Reactions of 4,40-ditellurobispyridine with HCl, MeI, a I2/(Ph3Te)I
stepwise addition or CoCl2$6H2O resulted in the formation of the
compounds 1, 2, 4 and 5. Compound 2 is readily oxidized by I2 to the
tellurium(IV) derivative 3. The reactions described above clearly
show the versatility of the diorganylditellurium compounds as
synthons. The synthetic routes are presented in Scheme 1. Crystal
data and structure refinement information for all compounds are
presented in Table 1. Selected bond lengths and angles are
summarized in Table 2.
The compounds 1, 2 and 3 belong to the rare examples of
discrete molecular zwitterions containing tellurium. For the
compound 1, the cationic fragment is generated owing to the
basicity of the pyridyl group toward the aqueous HCl. Simulta-
neously, the TeeTe bond of the ditelluride is cleaved and the “T-
shaped” tellurolate(II) anion is formed by the coordination of two
chloride ions. The formal negative charge of the tellurolate(II) anion
is stabilized by the formal positive charge of the pyridinium cation
located at the reverse side of the same molecule. The molecular
structure of 1 is shown in Fig. 1.
In the molecular structure of the compound 1 the coordination
around the tellurium atom is formed by bonding of two chlorines
atoms and the carbon atom of the pyridyl substituent. The presence
of two stereochemically active lone pairs on a tellurium atom
results in a T-shaped coordination geometry. The formal negative
charge of the tellurolate(II) anion at one site of the molecule is
balanced by the formal positive charge of the pyridinium group at
the opposite site of the same molecule. The zwitterionic molecule 1
Cl
Te
Cl
I
I
I
(3)
Me
N
Te
I
(1)
H
N
I2
HCl(aq)
(4)
N
I
I
I
I
MeI
(Ph3Te)I
Te
(2)
Te
(Ph3Te)
N
Te
I
Me
N
Te
I
N
CoCl2 . 6 H2O
Cl
Co
Cl
Cl
Co
Cl
N
Te
Te
Te
Te
N
Cl
Co
Cl
Te
N
N
N
Cl
Te
N
N
Cl
Co
Cl
Co
Te
Te
N
Cl
n
(5)
Scheme 1. Reactions of Te2Py*2:

S.S. dos Santos et al. / Journal of Organometallic Chemistry 723 (2013) 115e121
117
Table 1
Crystal data and structure refinement for 1e5.
1
2
3
4
5
Empirical formula
Formula weight
C5H5Cl2NTe
277.60
C12H14I4N2Te2
949.05
C30H24I8N2Te2
1456.65
C25H23I4N2O1Te2
1130.25
C30H24Cl2CoN6Te6
1363.98
Temperature (K)
293(2)
293(2)
293(2)
293(2)
293(2)
Crystal system, space group
Unit cell dimensions
Monoclinic, P21/n
Monoclinic, P21
Orthorhombic, Pna21
Orthorhombic, Pbcm
Tetragonal, P41212
ꢀ
a (A)
11.334(1)
5.7805(4)
11.895(1)
90
100.32(1)
90
766.7(1)
4; 2.405
4.485
512
8.088(1)
19.6192(6)
13.6982(5)
10.4206(3)
90
90
90
2800.5(2)
4; 3.455
10.905
7.9448(7)
18.718(1)
20.734(2)
90
90
90
3083.3
4; 2.435
5.917
2044
9.5086(4)
9.5086(4)
41.358(2)
90.00
90.00
90.00
3739.3(3)
4; 2.423
5.221
ꢀ
b (A)
10.919(1)
12.236(2)
90
92.87(1)
90
1079.1(2)
2; 2.921
8.419
ꢀ
c (A)
a
b
g
(ꢂ)
(ꢂ)
(ꢂ)
3
ꢀ
Volume (A )
Z; density calculated (g/cm3)
Absorption coefficient (mmꢁ1
F(000)
)
832
2512
2476
Crystal size (mm)
Theta range for data collection
Index ranges
0.55 ꢃ 0.407 ꢃ 0.33
0.2 ꢃ 0.13 ꢃ 0.1
0.14 ꢃ 0.086 ꢃ 0.061
0.5 ꢃ 0.5 ꢃ 0.35
2.7e29.3
ꢁ10 ꢄ h ꢄ 10
ꢁ21 ꢄ k ꢄ 25
ꢁ28 ꢄ l ꢄ 19
11,565
0.232 ꢃ 0.204 ꢃ 0.112
q
(ꢂ)
2.3e29.2
2.9e29.1
1.8e27
1.9e29.6
ꢁ15 ꢄ h ꢄ 15
ꢁ6 ꢄ k ꢄ 7
ꢁ16 ꢄ l ꢄ 16
7721
2045
98.2%
ꢁ7 ꢄ h ꢄ 11
ꢁ13 ꢄ k ꢄ 14
ꢁ16 ꢄ l ꢄ 16
7157
4983
98.5%
ꢁ24 ꢄ h ꢄ 25
ꢁ17 ꢄ k ꢄ 17
ꢁ13 ꢄ l ꢄ 13
35,484
5958
99.6%
ꢁ13 ꢄ h ꢄ 13
ꢁ8 ꢄ k ꢄ 13
ꢁ53 ꢄ l ꢄ 57
21,326
5284
100.0%
Reflections collected
Independent reflections
Completeness
4245
98.5%
Instrument
STOE IPDS
Integration (X-RED 32)
0.1401/0.3612
2045/0/82
1.498
STOE IPDS
Integration (X-RED 32)
0.3546/0.7223
4983/1/181
1.051
Bruker CCD
Multi-scan (SADABS)
0.8417/1.0000
5958/1/218
0.921
STOE IPDS
Integration (X-RED 32)
0.1111/0.2246
4245/0/154
1.114
Bruker CCD
Multi-scan (SADABS)
0.46943/0.76097
5284/0/175
1.065
Absorption correction
Min. and max. transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2
s
(I)]
R1 ¼ 0.0263
wR2 ¼ 0.0669
R1 ¼ 0.0323
wR2 ¼ 0.0905
R1 ¼ 0.0485
wR2 ¼ 0.1196
R1 ¼ 0.0655
wR2 ¼ 0.1236
0.1(1)
R1 ¼ 0.0276
wR2 ¼ 0.0567
R1 ¼ 0.0395
wR2 ¼ 0.0624
R1 ¼ 0.0560
wR2 ¼ 0.1341
R1 ¼ 0.0729
wR2 ¼ 0.1402
R1 ¼ 0.0583
wR2 ¼ 0.1695
R1 ¼ 0.0725
wR2 ¼ 0.1810
R indices (all data)a
Absolute structure parameter
Largest diff. peak and hole (e
ꢁ ꢀꢁ3
A
)
1.443 and ꢁ1.427
2.112 and ꢁ1.297
1.298 and ꢁ1.209
2.445 and ꢁ1.744
5.053 and ꢁ2.863
R1 ¼ jFo ꢁ Fcj=jFoj; wR2 ¼ ½wðFo2 ꢁ Fc2Þ2=ðwFo2Þꢀꢁ1=2
:
a
is quasi-planar in the solid, and this feature provides a three-
dimensional supramolecular assembly by forming long chains of
non-classical NeH/Cl hydrogen bonds and Te/Cl secondary
bonds. Fig. 2 illustrates the supramolecular network formed by
compound 1. This arrangement consists of a pair of molecules with
antiparallel orientation, which are connected by two Te/Cl inter-
a zwitterion, is shown in Fig. 4. In compound 3, the tellurium is
surrounded by four iodine atoms in the same plane. The carbon
atom of the methylpyridinium group and a stereochemically active
lone pair gives rise to a square-pyramidal geometry if we take into
account only the bonded atoms. In the solid state structure, the
asymmetric unit of this compound is formed by two independent
ꢀ
actions (3.763 A). One chloride from each molecule provides a Ne
molecules of
interactions.
3
without further important intermolecular
ꢀ
H/Cl interaction (2.531 A) with a third molecule, generating the
supramolecular architecture.
Compound Te2Py*2 and diiodine react to produce Py*TeI3 in situ,
which is converted to the anionic complex after the addition of
(Ph3Te)I. An ellipsoid representation of the mixed telluronium/
tellurolate adduct 4 is shown in Fig. 5. The [Py*TeI4]ꢁ anion shows
a distorted octahedral environment around the TeIV atom, with
Te/N contacts trans to the pyridyl group attached to tellurium. The
supramolecular network formed by compound 4 is depicted in
Fig. 6. Its structural features are quite different from those found for
its analogs in the literature [3,4]. While (R3Te)[RTeX4] compounds
exhibit typical secondary Te/X interanionic interactions,
compound 4 shows a linear anionic chain formed by extremely rare
intermolecular Te/N(pyridine) secondary bonds between the anions
along the crystallographic a axis (Fig. 6).
Compound 2 is obtained in moderate yields from a nucleophilic
attack of the pyridyl nitrogen atom to the electron deficient carbon
atom of MeI, forming a pyridinium cation. The cleavage of the Tee
Te bond of 4,40-ditellurobispyridine and the coordination of two
iodine atoms to the tellurium(II) atom generate a T-shaped coor-
dination geometry around the tellurium atom. Similarly to
compound 1, a tellurolate(II) anion is formed at this site of the
molecule. In this case the formal negative charge is balanced with
the formal charge of the methylpyridinium group. Thus, compound
2 also represents a zwitterionic molecule. The asymmetric unit of 2
consists of a dimeric arrangement (Fig. 3), in which the molecules
are connected by two simultaneous Te/I secondary bondings
(3.790 A, 3.829 A). No further important intermolecular interac-
tions are observed for this compound. The reaction of Te2Py*2 with
MeI also gives a yellow solid, insoluble in organic solvents (except
DMSO). The mass spectra for this compound points to a structure
built up by a (Py*TeMe2)þ or [(MePy*)TeMe]þ fragment (both forms
fit to a m/z ¼ 237.9863). As its solution in DMSO quickly decom-
poses, no further studies were carried out.
Single crystals of f½CoðTe2Py*2Þ2Cl2ꢀ$ðTe2Py2*Þgn (5) are formed
when a methanolic solution of Te2Py*2 is carefully added to an
aqueous solution of CoCl2$6H2O.The crystal structure of 5 consists
of a coordination polymer of ½CoðTe2Py*2Þ2Cl2ꢀn and independent
molecules of Te2Py*2 (Fig. 7). The cobalt atom is surrounded by four
pyridyl groups coordinating in equatorial positions and two
chlorido ligands in apical positions providing a distorted octahedral
geometry around the metal center. This polymeric, three-
dimensional structure is formed since the TeeTe bonds remain
ꢀ
ꢀ
Compound 3 was prepared by the oxidation of compound 2 by
iodine. The molecular structure of the product, which is also

118
S.S. dos Santos et al. / Journal of Organometallic Chemistry 723 (2013) 115e121
Table 2
ꢂ
ꢀ
Selected bond lengths (A) and angles ( ) for 1e5.
ꢂ
ꢀ
Compound
A
1
Te(1)eCl(1)
Te(1)eCl(2)
Te(1)eC(11)
N(1)eH(1)
Te(1)eI(1)
Te(1)eI(2)
Te(2)eI(3)
Te(2)eI(4)
C(11)eTe(1)
C(21)eTe(2)
I(11)eTe(1)
I(12)eTe(1)
I(13)eTe(1)
I(14)eTe(1)
I(21)eTe(2)
I(22)eTe(2)
I(23)eTe(2)
I(24)eTe(2)
Te(1)eC(1)
Te(2)eC(11)
I(1)eTe(1)
I(2)eTe(1)
C(11)eTe(2)
C(21)eTe(2)
2.5205(7)
2.6224(7)
2.120(2)
0.8600
2.9942(15) I(2)eTe(1)eI(1)
2.9049(15) I(3)eTe(2)eI(4)
2.9450(14) C(11)eTe(1)eI(1)
2.9509(14) C(11)eTe(1)eI(2)
2.143(13)
2.155(16)
2.9079(9)
2.9065(9)
2.9352(9)
2.9229(9)
2.9312(9)
2.9307(8)
2.9224(9)
2.8973(8)
2.168(9)
Cl(1)eTe(1)eCl(2)
C(11)eTe(1)eCl(1)
C(11)eTe(1)eCl(2)
177.04(2)
91.74(7)
90.95(7)
2
3
174.67(5)
176.08(5)
91.9(4)
91.8(4)
92.2(4)
C(21)eTe(2)eI(3)
C(21)eTe(2)eI(4)
I(12)eTe(1)eI(11)
I(11)eTe(1)eI(14)
I(12)eTe(1)eI(13)
I(14)eTe(1)eI(13)
C(1)eTe(1)eI(11)
I(22)eTe(2)eI(21)
I(24)eTe(2)eI(21)
I(24)eTe(2)eI(23)
C(11)eTe(2)eI(22)
91.7(4)
89.29(2)
89.41(3)
88.25(3)
92.89(3)
89.7(2)
90.97(2)
89.92(3)
90.89(3)
88.9(2)
Fig. 2. The supramolecular arrangement of compound 1. Hydrogen atoms were
omitted for clarity, except those related to NeH/Cl interactions.
and coordination polymers, have been prepared by simple reac-
tions starting from 4,40-ditellurobispyridine. The manifold of the
products demonstrates how versatile the use of the pyridyl or
others substituent at the diorganylditelluride may be in the
synthesis of novel tellurium compounds, particularly in the design
of supramolecular aggregates. By choosing other substituents at the
R groups of RTeTeR compounds will allow the generation of many
others similar classes of compounds, in which strong covalent
bonds act together with weak hydrogen bonds, long-range Te/I
bonds and coordinate forces in the assembly of supramolecular
networks.
2.166(9)
4
5
2.9206(7)
2.9114(6)
2.097(4)
I(2)eTe(1)eI(1)
89.95(2)
179.62(4)
90.06(2)
177.77(4)
89.809(18)
91.114(18)
95.7(7)
90.3(4)
174.0(4)
83.6(3)
I(1)eTe(1)eI(1)i
I(2)eTe(1)eI(1)i
I(2)ieTe(1)eI(2)
C(1)eTe(1)eI(1)
C(1)eTe(1)eI(2)
N(2)iiieCo(1)eN(2)iv
N(2)iiieCo(1)eN(1)
N(2)iveCo(1)eN(1)
N(1)eCo(1)eN(1)v
N(2)iveCo(1)eCl(1)
N(1)eCo(1)eCl(1)
N(1)eCo(1)eCl(1)v
2.132(13)
N(1)eCo(1)
C(3)eTe(1)
Cl(1)eCo(1)
N(2)eCo(1)ii
Co(1)eN(2)iii
Co(1)eN(2)iv
2.319(5)
2.169(5)
2.518(2)
2.298(5)
2.298(13)
2.298(15)
88.4(2)
91.37(18)
92.61(18)
174.66(18)
Te(3)eTe(3)vi 2.699(2)
Te(1)eTe(2)
C(8)eTe(2)
C(11)eTe(3)
After this initial article, we have already started to modify the
properties associated with the ditellurides RTeTeR and their
derivatives, e.g. their solubility in water.
2.6982(10) Cl(1)eCo(1)eCl(1)v
2.118(7)
2.132(16)
i
Symmetry transformations used to generate equivalent atoms: ¼ x,ꢁy þ 3/2,ꢁz;
ii
¼ x ꢁ 1/2,ꢁy þ 3/2,ꢁz þ 3/4; iii ¼ x þ 1/2,ꢁy þ 3/2,ꢁz þ 3/4; iv ¼ y ꢁ 1/2,ꢁx þ 1/
4. Experimental section
v
2,z ꢁ 1/4; ¼ ꢁy þ 1,ꢁx þ 1,ꢁz þ 1/2; iv ¼ ꢁy þ 2,ꢁx þ 2,ꢁz þ 1/2.
4.1. General
intact. Thus, each 4,40-ditellurobispyridine molecule acts as
bridging ligand between two cobalt atoms. Compound Te2Py*2 was
also used in reactions with a series of metal chlorides such as
CuCl2$2H2O, NiCl2$6H2O and MnCl2$4H2O. In all cases, we observe
immediate precipitation of extremely insoluble compounds.
Solvents and standard reagents were obtained commercially
(Aldrich or Sigma) and used without further purification, (Ph3Te)I
and Te2Py*2 were prepared following literature procedures
[5,24,31]. Elemental analyses (CHN) were obtained with a VARIO EL
analyzer (Elementar Analysensysteme GmbH) from São Paulo
University, Brazil. Infrared spectra were measured using a Bruker
Tensor 27 mid-IR spectrometer.
3. Conclusions
Five novel tellurium compounds, belonging to different chem-
ical classes such as zwitterions, telluroniumetellurolate complexes
4.2. X-ray structure determinations
Bruker CCD X8 Kappa APEX II or STOE IPDS 2T diffractometers
operated using graphite monochromator and Mo-K
a
radiation
ꢀ
(l
¼ 0.71073 A) were used for the X-ray structure analyses. The
Fig. 1. Asymmetric unit of compound 1, showing the quasi-planar zwitterionic
molecule.
Fig. 3. Asymmetric unit of compound 2, showing the pseudo-dimeric arrangement
promoted by secondary Te/I bonds.

S.S. dos Santos et al. / Journal of Organometallic Chemistry 723 (2013) 115e121
119
Fig. 4. Asymmetric unit for compound 3, in this case there are no secondary Te/I interactions.
structures were solved by direct methods with SHELXS and refined
with SHELXL with anisotropic displacement parameters for all non-
hydrogen atoms [32]. The positions of hydrogen atoms bonded to
carbon atoms were calculated for idealized positions and treated
with the “riding model” option of SHELXL. The positions of
hydrogen atoms bonded to nitrogen atoms were located in the final
Fourier maps and refined with isotropic displacement parameters.
More information about the structure determinations is given in
Table 1.
kept under stirring for 24 h. The yellow precipitate formed was
washed with MeCN and removed by filtration. The resulting dark
red solution was evaporated at room temperature to give single
crystals of 2. Yield: 0.150 g, 32% based on Te2Py*2 taken.
Properties: dark red crystalline substance. C6H7NTeI2 (474.54 g/
mol). C, H, N-Analysis (%), found: C ¼ 15.39, H ¼ 1.47, N ¼ 3.02; calc.:
C ¼ 15.19, H ¼ 1.49, N ¼ 2.95. IR (cmꢁ1, KBr): 3094, 3048, 2964
[
n
(CaryleH)]; 1615, 1547, 1482, 1445 [
n
(CeC),
g
n
(CeN)]; 1324, 1262,
-ring]; 471
1196, 1095, 1050 [
(CeTe)].
b(CeH)]; 960, 807 [ (CeH)]; 693 [b
[n
4.3. Synthesis of [(HPy*)TeCl2] (1)
4.5. Synthesis of [(MePy*)TeI4] (3)
To a solution of Te2Py*2 (0.412 g; 1 mmol) in 5 mL of CH2Cl2, 5 mL
of aqueous HCl (37%) were added. The system was closed and the
mixture was kept under stirring for 3 h. The yellow solid material
formed was collected by filtration and re-crystallized from MeOH.
Yield: 0.260 g, 45% based on Te2Py*2 taken.
To a suspension of finely ground (MePy*)TeI2 (0.475 g; 1 mmol)
in 10 mL of MeOH, solid I2 (0.254 g; 1 mmol) was added at r.t. After
stirring for 2 h, the black solid formed was collected by filtration
and re-crystallized from MeCN. Yield: 0.360 g, 50% based on Te2Py2*
taken.
Properties: yellow crystalline substance. C6H7NTeCl2 (277.61 g/
mol). C, H, N-Analysis (%), found: C ¼ 21.71, H ¼ 1.83, N ¼ 5.02; calc.:
Properties: dark red crystalline substance. C6H7NTeI4 (728.35 g/
mol). C, H, N-Analysis (%), found: C ¼ 11.38, H ¼ 1.02, N ¼ 2.16; calc.:
C ¼ 9.84, H ¼ 0.96, N ¼ 1.92. IR (cmꢁ1, KBr): 3094, 3048, 2924
C ¼ 21.63, H ¼ 1.83, N ¼ 5.05. IR (cmꢁ1, KBr): 3217, 3133 [
n(NeH)];
(CeN)]; 1262,
-ring]; 453
3049, 2916 [
n
(CaryleH)]; 1615, 1580, 1470 [
n
(CeC),
n
1233, 1204, 1104, 1053 [
b
(CeH)]; 804 [
g(CeH)]; 762 [b
[n
(CaryleH)]; 2360 (overtones); 1607, 1557, 1479, 1429 [
n
(CeC),
n(Ce
[
n
(CeTe)].
N)]; 1306; 1268, 1188, 1042 [
486 [ (CeTe)].
b
(CeH)]; 805[
g
(CeH)]; 695[ -ring];
b
n
4.4. Synthesis of [(MePy*)TeI2] (2)
To a solution of Te2Py*2 (0.412 g; 1 mmol) in 5 mL of CH2Cl2, 5 mL
of MeI were added. The system was closed and the mixture was
Fig. 6. The supramolecular arrangement of compound 4, with emphasis on the linear
connection between the anions via Te/N interactions. Hydrogen atoms were omitted
Fig. 5. Asymmetric unit of compound 3. Hydrogen atoms were omitted for clarity.
i
ii
i
Symmetry operations to generate equivalent atoms: ¼ x,y,ꢁz þ 1/2; ¼ x,ꢁy þ 3/
for clarity. Symmetry operations to generate equivalent atoms: ¼ x,ꢁy þ 3/2,ꢁz þ 1.
ii
2,ꢁz þ 1.
¼ 1 þ x,y,z.

120
S.S. dos Santos et al. / Journal of Organometallic Chemistry 723 (2013) 115e121
Fig. 7. A view of the polymeric structure of compound 5 showing the distorted octahedral coordination around the cobalt atoms. Hydrogen atoms were omitted for clarity.
i
ii
iii
Symmetry operations to generate equivalent atoms: ¼ ꢁx þ 1/2,y ꢁ 1/2,ꢁz þ 7/4; ¼ ꢁy þ 1,ꢁx þ 1,ꢁz þ 3/2; ¼ ꢁx þ 1/2,y þ 1/2,ꢁz þ 7/4.
4.6. Synthesis of (Ph3Te)[Py*TeI4] (4)
Appendix A. Supplementary material
A solution of Te2Py*2 (0.412 g; 1 mmol) in 30 mL of MeOH was
cooled in an ice bath, and solid I2 (0.761 g; 3 mmol) was added.
After stirring for 1 h, the ice bath was removed and the system was
kept at r.t. for 30 min. Then, solid (Ph3Te)I (0.972 g; 2 mmol) was
added to the dark mixture. After 1 h under stirring, the dark solid
was collected by filtration and re-crystallized from MeCN. Yield:
1.743 g, 80% based on Te2Py*2 taken.
CCDC 853335e853339 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
References
Properties: dark red crystalline substance. C23H19NTe2I4
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N ¼ 1.52%; calc.: C ¼ 25.76, H ¼ 1.79, N ¼ 1.31%. IR (cmꢁ1, KBr): 3045
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140349/2007-3 and 290017/2009-2) and with support of the
Center for Supramolecular Interactions (FU Berlin).

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