Tetrahydrofuran ring opening and unexpected oxidation of the furyl ring in the reaction of bis(2-furyl) ditelluride with iodine and triphenylphosphine

Article abstract of DOI:10.1016/j.poly.2013.08.026

The reaction of bis(2-furyl) ditelluride Fu₂Te₂ (1) with iodine in diethyl ether under ambient conditions expectedly yields FuTeI (2). The in situ reaction of 2 with triphenylphosphine affords Ph ₃PTe(Fu)I (3), which was characterized in the solid state by single crystal X-ray crystallography. The crystal structure of 3 shows linear P-Te-I backbone and T-shaped coordination around the tellurium atom. In the solid lattice, 3 exists as discrete molecules, which are lined together by a Ha?I hydrogen bonding network. There is no evidence of the secondary bonding Tea?I or Ia?I interactions, which are typical for many tellurium-iodine compounds. When this two-step reaction of Fu ₂Te₂ with I₂ and PPh₃ is carried out in tetrahydrofuran, a mixture of products is obtained. The main products, which were identified by single-crystal X-ray crystallography, are {Ph ₃P(C₄H₅O₂)}₂[TeI ₄] (4), {Ph₃P(CH₂)₄PPh ₃}[TeI₄]·2CH₂Cl₂ (5·2CH₂Cl₂), Fu₂Te (6), (CH ₂)₄TeI₂ (7), Ph₃PO, and elemental tellurium. The formation of the products has been discussed in terms of THF ring opening, abstraction of tellurium by PPh₃, and the conversion of the furyl ring in FuTeI into a lactone ring due to the presence of atmospheric moisture.

Full text of DOI:10.1016/j.poly.2013.08.026

Accepted Manuscript
Tetrahydrofuran ring opening and unexpected oxidation of the furyl ring in the
reaction of bis(2-furyl)ditelluride with iodine and triphenylphosphine
Sari M. Närhi, Kaisa Malo, Raija Oilunkaniemi, Risto S. Laitinen
PII:
S0277-5387(13)00589-5
DOI:
http://dx.doi.org/10.1016/j.poly.2013.08.026
POLY 10286
Reference:
To appear in:
Polyhedron
Received Date:
Accepted Date:
17 June 2013
6 August 2013
Please cite this article as: S.M. Närhi, K. Malo, R. Oilunkaniemi, R.S. Laitinen, Tetrahydrofuran ring opening and
unexpected oxidation of the furyl ring in the reaction of bis(2-furyl)ditelluride with iodine and triphenylphosphine,
Polyhedron (2013), doi: http://dx.doi.org/10.1016/j.poly.2013.08.026
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Tetrahydrofuran Ring Opening and Unexpected Oxidation of The Furyl Ring in The Reaction of
Bis(2-furyl)ditelluride with Iodine and Triphenylphosphine
Sari M. Närhi, Kaisa Malo, Raija Oilunkaniemi,* Risto S. Laitinen*
Department of Chemistry, University of Oulu, P.O. Box 3000, FI-90014 University of Oulu, Finland.
* E-mail: raija.oilunkaniemi@oulu.fi
Tel: (358294) 481686
Fax: (3588) 5531603
* E-mail: risto.laitinen@oulu.fi
Tel: (358294) 481611
Fax: (3588) 5531603

Abstract
The reaction of bis(2-furyl) ditelluride Fu2Te2 (1) with iodine in diethyl ether under ambient conditions
expectedly yields FuTeI (2). The in situ reaction of 2 with triphenylphosphine affords Ph3PTe(Fu)I (3),
which was characterized in the solid state by single crystal X-ray crystallography. The crystal structure
of 3 shows linear P – Te – I backbone and T-shaped coordination around the tellurium atom. In the
solid lattice, 3 exists as discrete molecules, which are lined together by a H···I hydrogen bonding
network. There is no evidence of the secondary bonding Te···I or I···I interactions, which are typical for
many tellurium-iodine compounds. When this two-step reaction of Fu2Te2 with I2 and PPh3 is carried
out in tetrahydrofuran, a mixture of products is obtained. The main products, which were identified by
single-crystal X-ray crystallography, are {Ph3P(C4H5O2)}2[TeI4] (4), {Ph3P(CH2)4PPh3}[TeI4]·2CH2Cl2
(5·2CH2Cl2), Fu2Te (6), (CH2)4TeI2 (7), Ph3PO, and elemental tellurium. The formation of the products
has been discussed in terms of THF ring opening, abstraction of tellurium by PPh3, and the conversion
of the furyl ring in FuTeI into a lactone ring due to the presence of atmospheric moisture.

1.
Introduction
Diaryl ditellurides R2Te2 react with iodine (I2) forming aryltellurenyl iodides RTeI which have been
used as intermediary compounds for the formation of different type of organotellurium compounds
containing tellurium iodine bonds [1-16]. A multitude of compounds with varying structural features
have been characterized and in addition to conventional covalent bonds, the description of bonding in
these compounds necessitates the use of concepts like hypervalence, multicenter bonding, charge-
transfer interactions, secondary bonding, as well as hydrogen bonding. As a consequence, in the solid
state the discrete molecules often form supramolecular lattices and even 1D, 2D, and 3D polymeric
networks.
Decomposition or rearrangement reactions are often observed upon solidification of aryltellurenyl
halogenides [3,16-19]. A common pathway in aryltellurenyl(II) halides involves migration of the
organic substituents and the formation of diaryltellurium dihalides and elemental tellurium [3,20]. Only
a few compounds have been observed, which retain their initial solution stoichiometry in the crystalline
state [3,4,15]. Even in these cases the monomeric species are often associated into larger frameworks,
as exemplified by the X-ray structure of PhTeI, which consists of cyclic tetrameric Ph4Te4I4 molecules
[3,4]. Smaller molecular units can, however, be stabilized in the solid state by bulky aryl groups, as
observed in 2,6-dimesitylphenyltellurenyl iodide 2,6-(mes)2C6H3TeI [11] and 2,3,5,6-
tetramethylphenyltellurenyl iodide (tmp)TeI [15]. Both show dimeric solid-state structures with
Te···Te, Te···I, and I···I interactions. Sterically even more demanding 2,4,6-tri-tert-
butylphenyltellurenyl iodide exhibits only discrete molecules without Te···Te, Te···I, or I···I
intermolecular contacts [21].

The reactions of diorganyl ditellurides with halogens also yield mixed-valence aryltellurenyl halides
RX2TeTeR [11]. The removal of the organyl group from RTeI also leads to the formation of
tetraiodidotellurate(II) and hexaiodidotellurate(IV) ions [13,15], and addition of second halide yields
[RTeX2]- [7,10,12,15]. Polyiodides are formed when an excess of iodine is used in the reactions, as
exemplified by (PyH)[tmpTeI3(I3)] and (PyH)3[dmephTeI2(I2)]2(I3) (dmeph = 2,6-dimethylphenyl)
[10,11,13-16]. The phenyltellurenyl iodide has also been stabilized by the addition of the Lewis base
Ph3P into the diethylether solution of PhTeI [4]. This reaction yields quantitatively Ph3PTe(Ph)I.
Tellurium tetrahalogenides react both as Lewis bases and Lewis acids. There are several examples of
adducts where tellurium tetrahalides have acted both as acceptors and as donors (see ref. 22, and
references therein). Chalcogen tetrahalogenides undergo spontaneous redox reactions with neutral
Lewis bases [23,24] and the reductive power of P(III) towards the Se and Te centers has been recently
recognized [24]. In the case of tellurium tetrachloride, the reaction with triphenylphosphine in an inert
atmosphere has been shown to yield [Ph3PCl]2[TeCl6] and Te(0) [24] as well as Ph3PCl2 and Te(0) [25]
or TeCl2, Te(0), and Ph3PO [26]. In ambient conditions, [Ph3PCl]+ reacts with the formation of Ph3PO
[23, 26]. These reactions indicate redox processes, in which phosphorus is oxidized from P(III) to P(V)
and tellurium is reduced. The reduction of the Group 16 elements to the elemental form in the presence
of two electron donors has been reported to be partially responsible for the limited information of
coordination of the electron-rich Lewis base to a Group 16 element center [24,27].
In this work, we have investigated the reaction of Fu2Te2 [Fu = 2-furyl, C4H3O] (1) with an equimolar
amount of I2 in diethyl ether or in tetrahydrofuran (THF). FuTeI (2) was found to be formed in both
solutions. With the treatment of the reaction solutions with Ph3P, Ph3PTe(Fu)I (3) was readily
precipitated from the diethylether solution. In THF, however, the THF ring opening and the redox

reactions of Te(II) and P(III) took place resulting in a mixture of products. The reactions were
monitored by NMR spectroscopy and the products were characterized by X-ray crystallography.
2.
Experimental
2.1. General Procedures
All reactions were carried out in air using dry solvents. The solvents (Et2O, THF) were dried over
Na/benzophenone and distilled under an argon atmosphere prior to use. Ph3P (Fluka) was dried under
dynamic vacuum. I2 (Aldrich) was stored under argon and used without further purification. Fu2Te2 [Fu
= 2-furyl, C4H3O] (1) was prepared by modifying the method described by Engman and Cava [28]. In
this work, potassium hexacyanoferrate(III) was used for the oxidation of FuTeLi [29].
2.2 Spectroscopic Methods
The 31P{1H} and 125Te NMR spectra were recorded on an Ascend 400 spectrometer operating at 161.98
and 126.34 MHz, respectively. The respective spectral widths were ca. 64 and 139 kHz. The pulse
widths were 24.25 and 10.00 μs, corresponding to the nuclear tip angles of 90 and 40, respectively. The
31P{1H} pulse delay was 5.00 s and that for 125Te 1.60 s. The 31P{1H} accumulations contained ca. 250
transients. The 125Te accumulations in the acquisition of the spectrum of FuTeI contained ca. 1000
transients. The 125Te NMR spectrum of the reaction mixture of FuTeI and PPh3 contained ca. 30000
transients. The spectra were recorded unlocked. 85 % H3PO4 and a saturated solution of Te(OH)6 were
used as external standards. The 31P chemical shifts were reported relative to the standard and the 125Te
chemical shifts relative to neat Me2Te [ (Me2Te) = (H6TeO6) + 712] [30].

2.3. X-ray Crystallography
Diffraction data for compounds 3 –7 were collected on a Nonius Kappa CCD diffractometer using
graphite monochromated Mo K radiation ( = 0.71073 Å). Crystal data and the details of the structure
determinations are given in Table 1. The structures were solved by direct methods using SHELXS-97
and refined using SHELXL-97 [31]. 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 Å) and in the methylene groups (C-H = 0.99 Å). In the final refinement
the calculated hydrogen atoms were riding with the carbon atom they were bonded to. The isotropic
thermal parameters of the aromatic hydrogen atoms were fixed at 1.2, and those of aliphatic hydrogen
atoms at 1.5 times to that of the corresponding carbon atom. The scattering factors for the neutral atoms
were those incorporated with the program. The highest peaks in the final residual electron density are
near to tellurium or iodine.
(Table 1 here)
2.4. Reactions of Fu2Te2 with I2 and PPh3 in Et2O
A solution of I2 (133 mg, 0.52 mmol) in Et2O (5 ml) was added to the solution of Fu2Te2 (1) (201 mg,
0.52 mmol) in Et2O (20 ml) in an ethanol-liquid nitrogen bath (T = ca. -115 °C). After 20 minutes the
cooling bath was removed and the reaction mixture was stirred for 1.5 h during which time it warmed
to the ambient temperature and the bright red color of the solution turned dark violet due to the
formation of FuTeI (2). The reaction solution was again cooled in an ethanol-liquid nitrogen bath, and

Ph3P (269 mg, 1.03 mmol) in 5 ml of Et2O was added dropwise into the solution. The formation of
yellowish precipitate of Ph3PTe(Fu)I (3) was immediately observed. After 20 minutes the bath was
removed and the stirring was continued for further 45 minutes allowing the mixture to warm to the
ambient temperature. The precipitate was removed by decantation and dried in an argon flow. Yield:
433 mg (72 % based on Ph3P). Anal. Calcd. for C22H18IOPTe 3: C 45.26, H 3.11. Found: C 44.75, H
3.14.
2.5. Reactions of Fu2Te2 with I2 and PPh3 in THF
The reactions of 1 with I2 and Ph3P in THF were carried out in a similar fashion to those in Et2O. The
addition of Ph3P to 2 resulted in the color change of the solution into reddish brown, but no precipitate
was formed. Upon prolonged stirring of the mixture, the reaction vessel was coated with “metallic”
grey layer of elemental tellurium.
The reaction mixture was filtered and the solvent was removed by evaporation upon which a dark, very
viscose oily material was formed. Most of the material dissolved in hexane/CH2Cl2 (1:1), and the
crystals of {Ph3P(C4H5O2)}2[TeI4] (4), {Ph3P(CH2)4PPh3}[TeI4]·2CH2Cl2 (5·2CH2Cl2), C4H8TeI2 (7),
and Ph3PO were grown from the mixture upon slow evaporation of the solvent. Crystals of Fu2Te (6)
were obtained upon sublimation in the cold trap.

3.
Results and Discussion
3.1. General
The reaction of Fu2Te2 (1) with I2 in Et2O or THF afforded FuTeI (2) (see Scheme 1). The formation of
2 in both solutions was confirmed by the 125Te NMR spectroscopy. A single 125Te NMR resonance at
867 ppm or 959 ppm was observed in the Et2O and THF solutions of 2, respectively.
The addition of Ph3P into the Et2O solution of 2 leads to a rapid formation of Ph3PTe(Fu)I (3) (see
Scheme 1). The product could be isolated in a good yield and identified by the determination of the
crystal structure. The reaction proceeded in a similar fashion to that reported previously for
diphenylditelluride [4]. The 31P{1H} NMR spectrum of the reaction solution showed two distinct,
rather broad resonances at approximately -7 and 25 ppm. The resonance at -7 ppm was assigned to
Ph3PTe(Fu)I (3) and that at 25 ppm to Ph3PO.
(Scheme 1 here)
In THF, the reaction of FuTeI (2) and PPh3 proceeded in a more complicated manner. The formation of
3 between FuTeI and PPh3 was not observed, but the reaction seemed to involve the ring opening of the
solvent together with redox processes involving tellurium. The reaction afforded a mixture of
{Ph3P(C4H5O2)}2[TeI4] (4), {Ph3P(CH2)4PPh3}[TeI4] (5), Fu2Te (6), (CH2)4TeI2 (7), Ph3PO, and Te(0).
The compounds were identified by X-ray crystallography. The crystal structures of 4 and 5 are
described below (see Section 3.3), that of 7 has been reported previously [23], and there are several
reports of the crystal structure determinations of Ph3PO [32-38].
The reaction of 2 with PPh3 in THF was also monitored with both 31P{1H} and 125Te NMR
spectroscopy. At the initial stages of the reaction, the 31P{1H} NMR spectrum showed relatively broad

resonance at -(18-20) ppm. It is likely to be due to Ph3PI2, the formation of which in the early stages of
the reaction seems quite reasonable [39,40]. With increasing reaction time, this resonance shifted
downfield and its intensity decreased. At the same time, new resonances at 11.7 ppm, 25 ppm and 32-
28 ppm were observed. Their intensities increased upon prolonged stirring of the reaction solution.
Since we have identified two of the end products in the reaction of 2 and PPh3 as 4 and 5, it is
reasonable to assume that the initially formed Ph3PI2 is converted to phosphonium and
tetraiodidotellurate ions consuming more I2 relative to PPh3 resulting in the formal increase of the
Ph3P:I2 molar ratio and consequently leads to a downfield shift of the high field resonance. This
dependence of the chemical shift on the Ph3P:I2 molar ratio has been suggested also earlier [39,40].
Since also elemental tellurium is formed in the reaction, the formation of the [TeI4]2- anion finds
support from its related preparations from Te, I2, and I- [41-43].
The 31P chemical shift of Ph3PO has been reported at 45 – 25 ppm depending on the solvent,
concentration, and the moisture content among other things [39,44]. Therefore a resonance, which has
been observed in the region 32-28 ppm in different reaction batches, is assigned to Ph3PO. The
resonances at 25 ppm and 11.7 are assigned to the {Ph3P(C4H5O2)}+ cation in 4 and the
{Ph3P(CH2)4PPh3}2+ cation in (5), respectively.
Upon prolonged stirring, the main resonances in the 125Te spectrum of the reaction mixture were
observed at 870 and 376 ppm. The resonance at 376 ppm was assigned to Fu2Te (6). The related Th2Te
(Th = 2-thienyl, C4H3S) has been reported to exhibit the 125Te resonance at 408 ppm [45]. The
resonance at 870 ppm was assigned to C4H8TeI2 (7). This compound has been reported to show the
125Te chemical shift at 929 ppm in DMSO [46]. Its formation in the reaction was confirmed by the unit
cell measurements of the crystals isolated from the reaction mixtures.

3.2. The crystal structure of Ph3PTe(Fu)I (3)
Suitable crystals of 3 for the X-ray structure analysis were obtained by recrystallization of the isolated
compound from toluene. The molecular structure of 3 is shown in Figure 1 together with the numbering
of the atoms and the selected bond lengths and angles.
(Figure 1 here)
The lattice of Ph3PTe(Fu)I (3) consists of discrete molecules. The P – Te – I fragment is nearly linear
displaying a bond angle of 176.80(7)°. The P – Te – C bond angle is 90.3(3)°. The T-shaped
coordination of tellurium indicates two stereochemically active lone pairs as a consequence of charge-
transfer interaction between tellurium and iodine atoms. For ionic [Ph3P(R)Te]+I-, a bent P – E – I (E =
chalcogen) linkage would be expected, as observed in [(Me3N)3PSePh]I (C – Se – P angle of 94.1(3)°)
[47]. The Te – I bond length in 3 is 3.1174(15) Å. It is longer than the Te – I single bond (sum of the
covalent radii for tellurium and iodine is 2.70 Å [48]). The Te – I bond length in 3 is, however,
comparable to that in Ph3PTe(Ph)I [3.0930(9) Å][4]. Consistently, the P – Te bond lengths in 3 and
Ph3PTe(Ph)I are identical {2.561(3) and 2.568(2) Å [4], respectively}. The Te – C bond length in 3 is
quite normal.
The discrete Ph3PTe(Fu)I molecules are linked together by a three-dimensional H···I and H···Te
network as shown in Figure 2. The shortest H···I contacts span a range 3.1563(9)-3.2849(10) Å and the
shortest Te...H contact is 3.2323(9) Å.
(Figure 2 here)

3.3. The crystal structures of {Ph3P(C4H5O2)}2[TeI4] (4) and {Ph3P(CH2)4PPh3}[TeI4].2CH2Cl2
(5.2CH2Cl2)
The molecular structures of 4 and 5·2CH2Cl2 are shown in Figure 3. The selected bond parameters in
the [TeI4]2- anion are shown in Table 2. All bond lengths and angles involving the cations are normal.
(Figure 3 here)
(Table 2 here)
The [TeI4]2- anion in both salts shows an approximate square-planar coordination geometry. The Te-I
bond lengths in 4 and 5 span a very narrow range of 2.9348(11)-2.9795(4) Å and the I-Te-I bond angles
o
show a range 88.43(1)-91.570(10) . The metrical parameters in [TeI4]2- ions are consistent with those
reported for [(Et3PO)2H]2[TeI4] [49], [Co(en)3][TeI4](I) [13], (C10H8S8)4[TeI4] [50], and (Et4N)2[TeI4]
[40].
The cation of the compound seems to have only little effect on the geometry of the anions and in the
lattice the anions generally occupy the voids between bulky cations. The coordination polyhedra of
tellurium atom is usually completed to trigonal bipyramidal or to octahedron by intermolecular
secondary interactions but in the case of [TeI4]2- ions these kind of intermolecular interactions are
generally absent [14,40,48,49], which is also the case in 4 and 5·2CH2Cl2. Only weak hydrogen bonds
connecting cations and anions have been previously observed [13]. In both salts the cations and anions
are linked together with weak H···I hydrogen bonds of 3.0000(1) - 3.0225(6) Å, as shown in Figure 4.
In addition, there are two symmetry-related Te···H hydrogen bonds of 2.7759(8) Å in 4. The cations are
also linked together by hydrogen bonds to the ketone oxygen atoms. The O···H contacts are 2.385(4)
and 2.416(4) Å.

(Figure 4 here)
3.4. The crystal structure of Fu2Te (6)
The molecular structure of Fu2Te (6) is shown in Figure 5 together with selected bond parameters. The
lengths of the Te-C bonds of 2.0836(4)-2.0847(4) Å in molecular Fu2Te (6) are close to single bond
lengths and agree well with those in the related bis(2-thienyl) telluride Th2Te [2.082(12)-2.103(10) Å]
[51]. The Fu2Te molecules are linked together into columns by a bifurcated H···O hydrogen bonding
network with two pairs of H···O contacts [2.6957(5)-3.1722(6) Å and 2.8017(7)-3.4188(8) Å], as
shown in Figure 6. The tellurium atoms of the neighbouring molecules also show Te···Te secondary
bonding interactions of 3.9733(11) Å. While Th2Te is not isomorphic with 6, its lattice shows similar
features exhibiting bifurcated hydrogen bonds and Te···Te secondary bonding interactions.
(Figure 5 here)
(Figure 6 here)
3.5. The pathway of the reaction of FuTeI and PPh3 in the THF solution
FuTeI (2) reacts with triphenylphosphine in THF and forms an oily reaction mixture. The
crystallization
by
using
the
1:1
solution
of
hexane
and
CH2Cl2
affords
{Ph3P(CH2)4PPh3}[TeI4]·2CH2Cl2 (5·2CH2Cl2), (CH2)4TeI2 (7), and Ph3PO indicating that the THF
ring opening plays a significant role in the reaction (see Scheme 1). The formation of 5 resembles that
of zwitterionic Ph3PO(CH2)4TeBr4 from Ph3P and TeBr4 in THF [52]. The THF ring opening and the
formation of 7 have previously been observed also in the reaction of Ph3P and TeI4 [23]. The THF,

dioxane, and thioxane ring opening reactions have recently been reviewed, expanded, and discussed in
terms of reactivity of frustrated Lewis pairs [53]. Furthermore, bimetallic sodium–magnesium and
sodium-manganese bases lead to the ring fragmentation of tetrahydrofuran with subsequent capture of
the fragments in a number of crystalline complexes [54].
Ph3PBr2 has been reported to react with THF to afford Ph3PO and BrCH2(CH2)2CH2Br [55]. Since the
reaction of BrCH2(CH2)2CH2Br with Ph3P has been reported to yield {Ph3P(CH2)4PPh3}2+ [56], the
presence of {Ph3P(CH2)4PPh3}2+ in 5·2CH2Cl2 can readily be rationalized to be due to the formation of
ICH2(CH2)2CH2I during the reaction of FuTeI with Ph3P in THF. This species has also been suggested
to be an intermediate in the formation of (CH2)4TeI2 (7) upon treating TeI4 with PPh3 [23].
The five-membered lactone ring in the {Ph3P(C4H5O2)}+ cation of 4 can originate either from THF or
from the furyl group of the reactant bis(2-furyl) ditelluride 1. It has been reported that
triphenylphosphine is oxidized to triphenylphosphine oxide in the presence of metallic catalyst in air-
saturated THF under nitrogen atmosphere [57]. After the oxidation, THF reacts to form butyrolactol
and butyrolactone. Butyrolactone can also be formed by the reaction of THF with molecular oxygen in
the presence of a metallic catalyst or a radical initiator [58-69]. The yield of γ‐butyrolactone in the
reactions varies from trace amounts to almost quantitative. γ-Butyrolactone, however, doesn’t readily
react at the 4-position although fluorination at the 4- or 5-position has been reported [70]. Ab initio
molecular orbital calculations have shown that the relative electron densities at 3-, 4-, and 5-positions
of the γ-butyrolactone ring are 3 ≈ 4 >> 5 [70]. This indicates that the nucleophilic attack of Ph3P
should most readily take place at the 5-position of the γ-butyrolactone, which is generally the position,
at which the butyrolactone ring is attacked. This is inconsistent with our observation of the formation
of {Ph3P(C4H5O2)}+ cation, where triphenylphosphine is attached at the 4-position.

The formation of the C4H5O2 ring, which is bound to the phosphorus atom of triphenyl phosphine at the
position 4, can be rationalized by the oxidation of the furyl group of 1, as shown in Scheme 2. When
Ph3P is added into the reaction mixture containing 2, part of it abstracts tellurium with the formation of
unstable Ph3PTe, which will be converted in ambient atmosphere into Ph3PO and elemental tellurium.
Another product is 2-furyl iodide. It can be expected to react with moisture in air resulting in the
removal of HI and the formation of 2-furyl hydroxide. Due to keto-enol equilibrium it can also exist as
a ketone. In this form the carbon in position 4 is slightly electron-deficient and can be conceived to
undergo a reaction with a nucleophile such as Ph3P. The final cation is formed with the reaction of a
H+, which was formed upon removal of HI from 2-furyl iodide.
The abstraction of tellurium by Ph3P may also explain the formation of Fu2Te (6) during the reaction.
(Scheme 2 here)
4.
Conclusions
The reaction of Fu2Te2 (1) with iodine yields FuTeI (2), which was treated in situ with PPh3. The
products in the reaction of Ph3P with FuTeI depend on the solvent. In Et2O, the reaction affords
Ph3PTe(Fu)I (2). When the reaction of 2 and Ph3P is carried out in THF, no evidence of the formation
of Ph3PTe(Fu)I is observed. The reaction yields a mixture of products comprising
{Ph3P(C4H5O2)}2[TeI4] (4), {Ph3P(CH2)4PPh3}[TeI4] (5), Fu2Te (6), (CH2)4TeI2 (7), Ph3PO, and
elemental tellurium. The formation of the {Ph3P(C4H5O2)}+ cation can be explained by the abstraction
of tellurium from 2 followed by the reaction of the resulting 2-furyl iodide with atmospheric moisture
and Ph3P. Compounds 5 and 7 are formed as a consequence of THF ring opening reactions induced by

triphenylphoshine. The reaction products were identified and characterized by single-crystal X-ray
crystallography and the reactions were monitored by 31P{1H} and 125Te NMR spectroscopy.
Appendix A. Supplementary data
CCDC 943627-943630 contain the supplementary crystallographic data for 3-6. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or
e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgement
Financial support from the Academy of Finland and the grant from Faculty of Science, University of
Oulu (to S. M. N.) are gratefully acknowledged.
6.
References
[1] O. Vikane, Acta Chem. Scand. A 29 (1975) 787-793.
[2] E. Schulz Lang, U. Abram, J. Strähle, Z. Anorg. Allg. Chem. 623 (1997) 1968-1972.
[3] E. Schulz Lang, R.M. Fernandes Jr., E.T. Silveira, U. Abram, E.M. Vázquez-López, Z. Anorg.
Allg. Chem. 625 (1999) 1401-1404.
[4] P.D. Boyle, W.I. Cross, S.M. Godfrey, C.A. McAuliffe, R.G. Pritchard, S. Sarwar, J.M.
Sheffield, Angew. Chem. Int. Ed. 39 (2000) 1796-1798.

[5] G.N. Ledesma, E. Schulz Lang, E.M. Vázquez-López, U. Abram, Inorg. Chem. Commun. 7
(2004) 478-480.
[6] E. Schulz Lang, G. Manzoni de Oliveira, G.A. Casagrande, J. Organomet. Chem. 691 (2006) 59-
64.
[7] G. Manzoni de Oliveira, E. Faoro E. Schulz Lang, G.A. Casagrande, Z. Anorg. Allg. Chem. 632
(2006) 659-663.
[8] E. Schulz Lang, G.N. Ledesma, U. Abram, M. Vega-Teijido, I. Caracelli, J. Zukerman-Schpector,
Z. Kristallogr. 221 (2006), 166-172.
[9] E. Schulz Lang, G.A. Casagrande, G. Manzoni de Oliveira, G.N. Ledesma, S.S. Lemos, E.E.
Castellano, U. Abram, Eur. J. Inorg. Chem. (2006) 958-964.
[10] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, J. Organomet. Chem. 691 (2006) 5867-5872.
[11] J. Beckmann, M. Hesse, H. Poleschner, K. Seppelt, Angew. Chem. 46 (2007) 8277-8280.
[12] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, J. Organomet. Chem. 694 (2009) 1557-1561.
[13] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, Polyhedron 28 (2009) 63-68.
[14] G. Manzoni de Oliveira, E. Faoro, E. Schulz Lang, Inorg. Chem. 48 (2009) 4607-4609.
[15] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, C.B. Pereira, J. Organomet. Chem. 695 (2010)
1480-1486.
[16] E. Faoro, G. Manzoni de Oliveira, E. Schulz Lang, C.B. Pereira, J. Organomet. Chem. 696 (2011)
2438-2444.
[17] R.T. Mahdi, J.D. Miller, J. Chem. Soc. Dalton Trans. (1983) 1071-1074.
[18] N.W. Alcock, W.D. Harrison, J. Chem. Soc. Dalton Trans. (1984) 869-875.
[19] J.V. Comasseto, R.E. Barrientos-Astigarraga, Aldrichimica Acta 33 (2000) 66-78.
[20] W.L. Dorn, A. Knöchel, P. Schulz, G. Klar,, Z. Naturforsch., Teil B 31 (1976) 1043-1047.
[21] T.M. Klapötke, B. Krumm, I. Schwab, Acta Crystallogr. Sect. C 61 (2005) o4045-o4046.

[22] B. Krebs, F.-P. Ahlers, Adv. Inorg. Chem. 35 (1990) 235-317.
[23] S.M. Närhi, R. Oilunkaniemi, R.S. Laitinen, M. Ahlgren, Inorg. Chem. 43 (2004) 3742-3750.
[24] J.L. Dutton, R. Tabeshi, M.C. Jennings, A.J. Lough, P.J. Ragogna, Inorg. Chem. 46 (2007) 8594-
8602.
[25] F.J. Berry, N. Gunduz, M. Roshani, B.C. Smith, Commun. Fac. Sci. Univ. Ankara, Ser. B, 22B
(1975) 21-23.
[26] M. Albeck, S. Shaik, J. Chem. Soc. Perkin Trans. 1 (1975) 1223-1229.
[27] J.L. Dutton, P.J. Ragogna, Inorg. Chem. 48 (2009) 1722-1730.
[28] L. Engman, M.P. Cava, Organometallics 1 (1982) 470-473.
[29] K. Y. Jen, M. P. Cava, J. Org. Chem. 48 (1983) 1449-1451.
[30] M.J. Collins, G.J. Schrobilgen, Inorg. Chem. 24 (1985) 2608-2614.
[31] G.M. Sheldrick, Acta Crystallogr. Sect. A 46 (1990) 467–473; ibid. A64 (2008) 112–122.
[32] G. Bandoli, G. Bartolozzo, D.A. Clemente, U. Croatto, C. Panattoni, J. Chem. Soc. A (1970)
2778-2780.
[33] A.I. Gusev, N.G. Bokii, N.N. Afonina, T.V. Timofeeva, A.E. Kalinin, Yu.T. Struchkov, Zh.
Strukt. Khim. 14 (1973) 116-125.
[34] G. Ruban, V. Zabel, Cryst. Struct. Commun. 5 (1976) 671-677.
[35] C.P. Brock, W.B. Schweizer, J.D. Dunitz, J. Am. Chem. Soc. 107 (1985) 6964-6970.
[36] A.L. Spek, Acta Crystallogr. Sect. C 43 (1987) 1233-1235.
[37] K.A. Al-Farhan, J. Crystallogr. Spectrosc. Res. 22 (1992) 687-689.
[38] J.A. Thomas, T.A. Hamor, Acta Crystallogr. Sect. C 49 (1993) 355-357.
[39] P. Deplano, S.M. Godfrey, F. Isaia, C.A. McAuliffe, M.L. Mercuri, E.F. Trogu, Chem.
Ber./Recueil 130 (1997) 299-305.

[40] N. Bricklebank, S.M. Godfrey, A.G. Mackie, C.A. McAuliffe, R.G. Pritchard, P.J. Kobryn, J.
Chem. Soc. Dalton Trans. (1993) 101-103.
[41] S. Pohl, W. Saak, B. Krebs, Z. Naturforsch., Teil B 40 (1985) 251-257.
[42] P.C. Srivastava, H.G. Schmidt, H.W. Roesky, Z. Naturforsch., Teil B 50 (1995) 695-696.
[43] P.C. Srivastava, S. Bajpai, Synth. React. Inorg. Metal-Org. Chem. 29 (1999) 1793-1804.
[44] G.E. Maciel, R.V. James, Inorg. Chem. 3 (1964) 1650-1651.
[45] M.J. Poropudas, L. Vigo, R. Oilunkaniemi, R.S. Laitinen, Heteroatom Chem. 22 (2011) 348-357.
[46] A.Z. Al-Rubaie, H.A.Y. Alshirayda, P. Granger, S. Chapelle, J. Organomet. Chem. 287 (1985)
321-327.
[47] S.M. Godfrey, R.T.A. Ollerenshaw, R.G. Pritchard, C.L. Richards, J. Chem. Soc. Dalton Trans.
(2001) 508-509.
[48] J. Emsley, The Elements, third ed., Oxford University Press, New York, 1998.
[49] J. Konu, T. Chivers, Dalton Trans. (2006) 3941-3946.
[50] M. Fujiwara, N. Tajima, T. Imakubo, M. Tamura, R. Kato, J. Solid State Chem. 168 (2002) 396-
407.
[51] G. Bandoli, J. Bergman, K.J. Irgolic, A. Grassi, G.C. Pappalardo, Z. Naturforsch., Teil B, 40
(1985) 1157-1160.
[52] S.M. Kunnari, R. Oilunkaniemi, R.S. Laitinen, M. Ahlgren, J. Chem. Soc., Dalton Trans. (2001)
3417-3418.
[53] B. Birkmann, T. Voss, S. J. Geier, M. Ullrich, G. Kehr, G. Erker, D.W. Stephan, Organometallics
29 (2010) 5310-5319.
[54] R.E. Mulvey, V.L. Blair, W. Clegg, A.R. Kennedy, J. Klett, L. Russo, Nature Chem. 2 (2010)
588-591.
[55] A.G. Anderson Jr., F.J. Freenor, J. Org. Chem. 37 (1972) 626-630.

[56] J.-C. Chang, W.-Y. Ho, I-W. Sun, Y.-K. Chou, H.-H. Hsieh, T.-Y. Wu, S.-S. Liang, Polyhedron
29 (2010) 2976-2984.
[57] R.F. Moreira, E.Y. Tshuva, S.J. Lippard, Inorg. Chem. 43 (2004) 4427-4434.
[58] M. Aresta, C. Fragale, E. Quaranta, I. Tommasi, J. Chem. Soc. Chem. Commun. (1992) 315-317.
[59] M. Sommovigo, H. Alper, J. Mol. Catal. 88 (1994) 151-158.
[60] P. Li, H. Alper, J. Mol. Catal. 72 (1992) 143-152.
[61] T. Akindele, K.-I. Yamada, K. Tomioka, Acc. Chem. Res. 42 (2009) 345-355.
[62] Y. Yamamoto, K.-i. Yamada, K. Tomioka, Tetrahedron Letters 45 (2004) 795-797.
[63] M.T. Reetz, K. Töllner, Tetrahedron Letters 36(52) (1995) 9461-9464.
[64] R.C. Luckay, X. Sheng, C.E. Strasser, H.G. Raubenheimer, D.A. Safin, M.G. Babashkina, A.
Klein, New J. Chem. 34 (2010) 2865-2840.
[65] M. Salavati-Niasari, Inorg. Chem. Commun. 9 (2006) 628-633.
[66] M. Salavati-Niasari, N. Mir, J. Incl. Phenom. Macrocycl. Chem. 59 (2007) 223-230.
[67] M.T. Hay, S.J. Geib, D.A. Pettner, Polyhedron 28 (2009) 2183-2186.
[68] T. Straub, A.M.P. Koskinen, Inorg. Chem. Commun. 5 (2002) 1052-1055.
[69] R.F. Moreira, E.Y. Tshuva, S.J. Lippard, Inorg. Chem. 43 (2004) 4427-4434.
[70] Y. Sasaki, R. Ebara, N. Nanbu, M. Takehara, M. Ue, J. Fluorine Chem. 108 (2001) 117-120.

Table 1. Details of the structure determinations of Ph3PTe(Fu)I (3), {PPh3(C4H5O2)}2[TeI4] (4), {Ph3P(CH2)4PPh3}[TeI4]·2CH2Cl2 (5·2CH2Cl2),
and Fu2Te (6).
6
3
4
5·2CH2Cl2
formula
fw
C22H18OPTeI
583.83
C44H40O4P2Te I4
1329.90
C42H42Cl4I4P2Te
1385.70
C8H6O2Te
261.73
crystal system
space group
a, Å
monoclinic
P21/c
triclinic
monoclinic
P21/c
monoclinic
P21/c
P-1
9.975(2)
9.6853(19)
10.682(2)
11.774(2)
84.56(3)
9.7152(2)
22.6322(4)
11.2653(3)
5.4735(11)
18.758(4)
8.1454(16)
b, Å
24.234(5)
9.0769(18)
c, Å
, deg
106.0150(10)
, deg
105.95(3)
76.86(3)
93.07(3)
, deg
75.92(3)
1149.7(4)
1
V
2109.8(7)
4
2380.46(10)
2
835.1(3)
4
Z
T (K)
calcd, g cm 3
120(2)
1.838
120(2)
1.921
120(2)
1.933
120(2)
2.082
(MoK ), mm 1
2.957
3.441
3.539
3.506
F(000)
1112
630
1312
488
crystal size (mm3)
0.10 × 0.10 × 0.05
0.25 x 0.25 x 0.25
0.10 x 0.10 x 0.05
0.40 × 0.20 × 0.20

θ range (o)
3.17 – 25.00
8103
3.12 – 26.00
18026
1.80 -26.00
24427
3.32 – 25.99
3562
reflns collected
unique reflns
3633
4458
4656
1588
Parameters
146
250
241
101
Goodness-of-fit on F2 a 1.119
1.154
1.043
1.124
Rint
0.0779
0.0637
0.1189
0.0969
0.1346
0.0358
0.0305
0.0877
0.0366
0.0877
0.0391
0.0390
0.0872
0.0562
0.0926
0.0988
0.0491
0.1335
0.0584
0.1395
b
R1
b
wR2
R1 (all data) c
wR2 (all data) c
Largest diff. peak and
hole (e Å3)
0.911; -1.062
1.875; -1.132
98.8 %
1.425; -1.350
100.0 %
1.205; -1.376
96.9 %
completeness
98.0 %
2
½
a Goof = { Σ [ w(Fo – Fc2)2 ] / (n –p) } ( n = number of reflections, p = total number of parameters refined). b I ≥ 2 (I).
2
2 2
½
c R1 = [ ||Fo|-|Fc||]/[ |Fo|], wR2 = {[ w(Fo -Fc2)2]/[ w(Fo ) ]} .

Table 2. Selected bond lengths (Å) and angles (o) in the [TeI4]2- anions in {PPh3(C4H5O2}[TeI4] (4)
and {Ph3P(CH2)4PPh3}[TeI4]·2CH2Cl2 (5·2CH2Cl2)
4
5
Te1-I1
Te1-I2
2.9348(11)
2.9494(8)
2.9795(4)
2.9606(4)
I1-Te1-I2
I1-Te1-I1a
I1-Te1-I2a
I2-Te1-I2a
91.28(3)
180.0
88.72(3)
180.0
88.425(10)
180.0
91.575(10)
180.0
a Symmetry operations: 4: 1-x, -y, -z. 5: 1-x, 1-y, 1-z

Figure Captions
Figure 1. The crystal structure of Ph3PTe(Fu)I (3) indicating the numbering of the atoms. The
anisotropic displacement parameters have been drawn at 50 % probability level. Selected bond
lengths (Å) and angles (o): Te1-I1 3.1174(15), Te1-P1 2.561(3), Te1-C1 2.092(10), P1-C111
1.802(11), P1-C121 1.801(11), P1-C131 1.793(11); I1-Te1-P1 176.80(7), I1-Te1-C1 89.4(3), P1-
Te1-C1 90.3(3), Te1-P1-C111 115.8(4), Te1-P1-C121 117.0(4), Te1-P1-C131 101.1(4), C111-P1-
C121 104.4(5), C111-P1-C131 109.4(5), C121-P1-C131 108.9(5).
Figure 2. The linking of the discrete Ph3PTe(Fu)I (3) molecules by H···I and H···Te hydrogen bonds.
The van der Waals’ radii of hydrogen, tellurium, and iodine have been superimposed to emphasize
these interactions. The tetrahedra around the phosphorus centers have been indicated for clarity.
Figure 3. The crystal structures of (a) {Ph3P(C4H5O2)}2[TeI4] (4) and (b)
{Ph3P(CH2)4PPh3}[TeI4]·2CH2Cl2 (5·2CH2Cl2) indicating the numbering of the atoms. The
anisotropic displacement parameters have been drawn at 50 % probability level.
Figure 4. The H···I and H···Te hydrogen bonding networks in (a) (a) {Ph3P(C4H5O2)}2[TeI4] (4) and
(b) {Ph3P(CH2)4PPh3}[TeI4]·2CH2Cl2 (5·2CH2Cl2). The van der Waals’ radii of hydrogen, tellurium,
and iodine for the relevant interactions have been superimposed to emphasize these interactions. The
solvent molecules have been omitted and the tetrahedra around the phosphorus centers have been
indicated for clarity.
Figure 5. The crystal structure of Fu2Te (6) indicating the numbering of the atoms. The anisotropic
displacement parameters have been drawn at 50 % probability level. Selected bond lengths (Å) and
angles (o): Te1-C11 2.084(5), Te1-C21 2.085(5); C11-Te1-C21 96.9(2).

Figure 6. The H···O hydrogen bonds and the Te···Te secondary bonding interactions in Fu2Te (6).
The van der Waals’ radii of hydrogen, oxygen, and tellurium have been superimposed to emphasize
these interactions.
Scheme 1. The reactions of Fu2Te2 (Fu = 2-furyl, C4H3O) with iodine and triphenyl phosphine in
Et2O and THF.
Scheme 2. A possible pathway to the formation of {Ph3P(C4H5O2)}+ from Fu2Te2.

Crystallographic information of 3-6 have been deposited with the Cambridge Crystallographic Data
Center as supplementary publication numbers CCDC 943627-943630, 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].

C131
C121
P1
Te1
C111
I1
C11
O1
Figure 1

b
a
Figure 2

(a)
I2
I1
P1
Te1
O1
O2
(b)
P1
I2
I1
Te1
Cl1
Cl2
Figure 3

(a)
(b)
Figure 4