Cyclodimerization of phenyliodoacetylene with elemental tellurium: New pathway to 1.3-ditellurofulvenes

Article abstract of DOI:10.1016/j.jorganchem.2010.08.056

Thermal reaction between PhCCI and powdered Te afforded a mixture of (E)-4-iodo-2-(iodo(phenyl)-5-phenyl-1,3-ditellurofulvene (1) and (Z)-4-iodo-2-(iodo(phenyl)-5-phenyl-1-(diiodo),3-ditellurofulvene (2), which was subsequently reduced to (Z)-4-iodo-2-(iodo(phenyl)-5-phenyl-1,3- ditellurofulvene (3). Formation of 1 and 3 as the thermodynamically most stable products has been rationalized using density functional theory (DFT) calculations. Molecular structures of 1-3 were established crystallographically. In the solid state the coordination sphere of both tellurium atoms in 2 is extended by weak intermolecular Te?π interactions with the solvate molecule of toluene which completes the pseudo-trigonal bipyramidal coordination geometry around each Te atom and assembles 2 into the chains along the crystallographic c-axis.

Full text of DOI:10.1016/j.jorganchem.2010.08.056

Journal of Organometallic Chemistry 696 (2011) 496e503
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Cyclodimerization of phenyliodoacetylene with elemental tellurium:
New pathway to 1.3-ditellurofulvenes
,
b,c,
Yury Torubaev a , Pradeep Mathur d, Badrinath Jha b, Shaikh M. Mobin d, I.V. Skabitsky a
*
a N.S. Kurnakov Institute of General and Inorganic Chemistry, Russ. Acad. Sci. 119991 Moscow, GSP-1, Leninsky prospect, 31, Russia
b Chemistry Department, Indian Institute of Technology Bombay, Powai, Bombay 400076, India
c School of Sciences, Indian Institute of Technology Indore, Khandwa Road, Indore 452017, India
d National Single Crystal X-ray Diffraction Facility, Indian Institute of Technology Bombay, Powai, Bombay 400076, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Thermal reaction between PhC^CI and powdered Te afforded a mixture of (E)-4-iodo-2-(iodo(phenyl)-
5-phenyl-1,3-ditellurofulvene (1) and (Z)-4-iodo-2-(iodo(phenyl)-5-phenyl-1-(diiodo),3-ditellurofulvene
(2), which was subsequently reduced to (Z)-4-iodo-2-(iodo(phenyl)-5-phenyl-1,3-ditellurofulvene (3).
Formation of 1 and 3 as the thermodynamically most stable products has been rationalized using density
functional theory (DFT) calculations. Molecular structures of 1e3 were established crystallographically.
In the solid state the coordination sphere of both tellurium atoms in 2 is extended by weak intermo-
Received 22 June 2010
Received in revised form
27 August 2010
Accepted 31 August 2010
Available online 15 September 2010
lecular Te/
p interactions with the solvate molecule of toluene which completes the pseudo-trigonal
Keywords:
bipyramidal coordination geometry around each Te atom and assembles 2 into the chains along the
crystallographic c-axis.
Ditellurofulvene
Organotellurium halides
DFT
Ó 2010 Elsevier B.V. All rights reserved.
Te/
p interactions
Short contacts
X-ray crystallography
1. Introduction
convert to 3,5-di-tert-butyl-1,2,4-tritellurolane on treatment with an
excess of elemental tellurium [3] (Scheme 3).
Treatment of p-RC6H4C^CꢀNaþ (R]H, Me) with Te powder
followed by acidification with etherial HCl (Scheme 1) to give
1,3-ditellurofulvene (I), as first reported in 1979 [1], led to extensive
investigations of this and related reactions.
Substitution of etherial HCl by CF3CO2H as a protonating agent
for PhChCTeNa resulted in cis/trans e mixture of 1,3-ditelluretanes
(IIeIII) along with a minor quantity of E-1,3-ditellerofulvene (I)
(Scheme 4) [4].
Re-investigation of the synthesis, conducted in 1981 [1],
recognized the major product as a cis/trans- mixture of 1,3-ditel-
luretanes (II and III) but not 1,3-ditellurofulvene I (Scheme 2).
Both isomers were separated, and the cis-isomer (II) has been
found to undergo cis-trans isomerisation under the action of acidic
catalyst or UV-irradiation. However, only the trans-isomer (III) was
characterized by X-ray diffraction. In the same year, another research
group supported the structural proof for trans-1,3-ditelluretane (III)
as a major product and separated the additional minor byproduct
which was structurally characterized as 1,2,4-tritellurolane (IV)
(Scheme 2) [2]. It must be mentioned that 2,4-di-tert-butyl-1,3-
ditelluretane (obtained via transient telluroaldehyde in the reaction
of vanadium alkylidene complex [(N(2-PiPr2-4-methylphenyl))2V
(CHBu)2] with an excess of elemental Te) was recently shown to
Selective preparation of either 1,3-ditellurofulvene or the
1,3-ditelluretane derivatives controlled by the conditions of ethy-
nyltellurolate anion protonation has also been developed
(Scheme 5) [5].
Due to the known property of unstable tellurocarbonic species
to cyclodimerize to give 1,3-ditelluretanes (Scheme 6) [3,6e8],
telluroketene was assumed to be an intermediate precursor of 1,3-
ditelluretane, but no precursors or intermediates were suggested
for 1,3-ditellurofulvene in (Scheme 6) [5].
Treatment of phenylacetylene with tellurium under strong basic
conditions, investigated by Potapov et al. [9] and subsequently re-
investigated by the Wudl group [10] afforded 1:1 E/Z mixture of
1,3-ditellurafulvenes (I) (Scheme 7).
Interestingly, these findings stimulated the preparation of hexa-
methylenetetratellurafulvalene (HMTTeF) [11] which was the first
example of a tetratellurofulvalene (TTeF); assumed instability of
such compounds thought to occur due to very large-sized tellurium
atoms incorporated in a five-membered ring. At the same time, the
* Corresponding author. Tel.: þ7 495 9543841.
E-mail address: hansmail@rambler.ru (Y. Torubaev).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.08.056

Y. Torubaev et al. / Journal of Organometallic Chemistry 696 (2011) 496e503
497
R
or asymmetrical 5-membered ((E)-4-iodo-2-(iodo(phenyl))-5-
phenyl-1,3-ditellurofulvene) molecules (Scheme 9, c and d).
Known examples of 6-membered 1,4-ditellurines structures
typically exhibit non-planar geometry of a heterocyclic ring folded
along the TeeTe line with a dihedral angle of approximately 60ꢁ
[15,16]. Therefore, 1,3-ditellurofulvene appears to be the most
rational solution. In fact, XRD investigation of 3, which exhibits
much less disorder in the positions of vinylidenic carbon atoms,
has undoubtedly revealed its (Z)-4-iodo-2-(iodo(phenyl))-5-
phenyl-1,3-ditellurofulvene structure (Fig. 3). By analogy, the same
1,3-ditellurofulvene core was assigned to 1 and 2 (Figs. 1 and 2).
Intramolecular bond lengths and bond angles as well as the
slight deviations from planar geometry in the 1,3-ditellurole ring of
1e3 are in good agreement with those in 1,3-ditellurole [17] and
TTeFs [18,19]. The crystal packing of 1 follows the same pattern as
observed in TTeFs and short intermolecular Te/Te (1 þ x, y, 1 þ z)
interaction (3.881 Å) assembles the molecules of 1 into the plain
chains (see Fig. 4) zigzag packed along the crystallographic b-axis,
which appears to be the longest dimension of unit cell of 1
(a ¼ 5.7173(3) Å, b ¼ 23.4033(10) Å, c ¼ 6.8514(4) Å). All relevant
crystallographic details for 1e3 are given as Supplementary
material.
Te
HCl / Et2O
Te
C-Na+
Ph-C
CTe-Na+
Ph-C
CHR
Te
H
C6H5
=
I,
Ia
R
C6H4Me
Scheme 1. First report on 1,3-ditellurofulvene formation by PhC2TeNa acidification.
TTeFs were expected to be better conducting materials than tetra-
thiafulvalenes (TTF) due to more diffuse nature of tellurium atomic
orbitals and consequent increase of secondary intermolecular
interactions in the crystal lattice, resulting in materials with
enhanced metallic electrical conductivity, as was subsequently
shown experimentally [12].
2. Results and discussion
In the course of our investigations on the interaction of organic
telluro-halides with acetylenes and metalecarbonyl complexes
[13] we intended to prepare (PhChC)2TeI2 following the Te into CeI
bond insertion method known for alkyliodides (Scheme 8) [14].
No reaction was observed while stirring PhChCI with Te
powder in toluene at room temperature, but subsequent refluxing
of the reaction mixture for 6 h yielded a mixture of (E)-4-iodo-
2-(iodo(phenyl))-5-phenyl-1,3-ditellurofulvene (1), and (Z)-4-iodo-
2-(iodo(phenyl))-5-phenyl-1(diiodo),3- ditellurofulvene (2). The
two isomers were separated by chromatographic techniques as
orange-red air stable solids. Reduction of 2 by aqueous Na2S2O3
produced the cis-isomer of 1: (Z)-4-iodo-2-(iodo(phenyl))-
5-phenyl-1,3-ditellurofulvene (3) (Scheme 8).
Crystal structure investigation revealed that molecules of 1 and
2 have a centre of inversion and m-plane symmetry elements
accordingly. Both have a planar 1,3-ditellurofulvene core having
two pairs of iodo and phenyl groups oriented in the trans (1) and cis
(2) configuration relative to it. Each pair or vinylidenic carbon
atoms in 1 and 2 are disordered over four positions with equal
occupancy so that cyclic or exocyclic double bonds could not be
unambiguously distinguished within one molecule (Scheme 9).
Based on X-ray data we can assume that disorder may arise from
In contrast to the Te-diiodinated TTeF [19], characteristic
intermolecular Te/I interactions are absent in the Te-diiodinated
1,3-ditellurofulvene 2. Instead of iodine atom, the coordination
sphere of tellurium is extended by weak intermolecular Te1/
p
interactions with the solvate molecule of toluene, which occurs at
a distance of 3.462 Å from Te1 and is oriented in the same
direction as the Te1 lone electron pair, thus completing the
pseudo-trigonal bipyramidal coordination geometry around the Te
centre. Literally, per contra toluene molecule is faces the non-
iodinated Te2 atom of the neighboring molecule of 2(x, y, 1 þ z),
occurring at a distance of 3.405 Å from the Te2 and associating
molecules of 2 into the chains along the crystallographic c-axis
(Fig. 5). This gives a clear evidence of rare Te/p-arene weak
interaction [20].
Only
a solvate arene (toluene) molecule are reported [21e23] (see Fig. 6),
thus “multidecker” chain-like Te/ association (normally observed
3 structures containing Te/p-ring interaction with
p
a
“juxtaposure” of symmetrical 4-membered (2E,4E)-2,4-bis
in metal-cyclopentadienyl solid state structures (i.e. Cp2Pb,
Cp2Pb*C5H6 [24], (h1-Cp)SbCl2 [25])) formed in the crystal of 2 is
unique.
(iodo(phenyl))-1,3-ditelluretane (Scheme 9, a) and 6-membered
2,5-diiodo-3,6-diphenyl-1,4-ditellurine (Scheme 9, b) molecules
Scheme 2. Re-investigation of the first report on PhC2TeNa acidification [2].
t
t
t
t
Te
Te
Bu
H
Bu
H
Bu
H
CH Bu
t
t
Te
Bu
H
Bu
H
Te (excess)
-
(PNP)V(Te)2
Te
(PNP)V
Te
t
CH Bu
Te Te
Scheme 3. Formation of 1,3-ditelluretane via cyclodimerization of transient telluroaldehyde and its further convertion to 1,2,4-tritellurolane [3].
Ph
Te
Te
CF3COOH
H
Te
CTe-Na+
PhCH
C-Na+
Ph-C
Ph-C
CHPh
+
Te
Ph
Te
H
II / III
I
Scheme 4. Formation of 1,3-ditelluretane and 1,3-ditellurofulvene by PhC2TeNa acidification by CF3COOH [4].

498
Y. Torubaev et al. / Journal of Organometallic Chemistry 696 (2011) 496e503
Me3Si
Te
H
SiMe3
Te
H
T
R
t-BuOH
C
Te-
Me3Si
C
-
2
o
0
,
C
F3
C
O
Te
Te
Me3Si
H
H
Me3Si
O
H
C
Te
C
H
SiMe3
Scheme 5. Controlled formation of 1,3-ditellurane and 1,3-ditellurofulvene by RC2Te anion acidification under various conditions [5].
Te
Te
Te
t
Bu
Te
Te
Te
=
Te
H
O
Te
Scheme 6. Formation of 4-membered 1,3-ditelluretanes via cyclodimerization of unstable telluroketones and telluroaldehydes [3,6e8].
It must be noted that despite the fact that the plane of a toluene
destruction usually observed in crystallosolvates, and had
preserved their color, habit and X-ray diffracting properties.
There was no observable reaction between Te and 1,2-diodo-
acetylene or 1-iodo-propyn-3-ol, under the same conditions as
those used for the phenylacetylene reaction, and in both cases there
was no significant change in the color of the reaction mixture, and
the Te was recovered almost quantitatively. In the reaction of Se
powder with phenylacetylene in refluxing toluene, formation of
elemental iodine vapors and blackish resin-like material insoluble
in common organic solvents was observed.
Recent quantum chemical studies of the reaction of SeCl2 with
(H2C]CH)2S have demonstrated that 6-membered thiaselenane
tends to rearrange into 5-membered thiaselenolane due to the
higher thermodynamic stability of the latter (see Scheme 10) [26].
We can therefore assume a similar rearrangement of interme-
diate 6-membered 2,5-diiodo-3,6-diphenyl-1,4-ditellurine (arising
molecule occurs at almost equal distances (3.462e3.405 Å) from
the neighboring Te(IV) and Te (II) atoms, inclusion of toluene was
not observed in the crystals of 1, which was crystallized from the
same mother-liquor as 2. Crystals of 2 are air stable and even after
1 month storage in an open sample tube did not suffer the
Ph
Te
Te
CHPh
Ph-C
CH
KOH/HMPA/SnCl2/H2O
Te
H
I
Scheme 7. Formation of 1,3-ditellurafulvenes on treatment of phenylacetylene with
elemental Te under strong basic conditions [9e10].
as
a
result of transient phenylethynyl tellurenyliodide
I
I
Ph
I
Ph
I
Te
Te
Te
I
Ph
I
+
Ph
Te
1
2
Te
Ph-C
C-I
Toluene /reflux/ 6 h
X
Na2S2O3
Ph
Ph
2R-I + Te = R2TeI2
Ph
I
Te
Ph
Te
R : Me, Et, Pr, Bu, C5H11
,
I
I
I
Te
3
Scheme 8. Formation of 1,3-ditellurofulvenes 1 and 2 on thermal interaction of phenyliodoacetylene with elemental Te.

Y. Torubaev et al. / Journal of Organometallic Chemistry 696 (2011) 496e503
499
Scheme 9. Vinylydenic carbon atoms disorder in the solid state structure of 1 (showing thermal ellipsoids at the 50% probability level) and its possible interpretation as “jux-
taposure” of a and b or c and d.
cyclodimerization) into the 5-membered ((E)-4-iodo-2-(iodo
(phenyl))-5-phenyl-1,3-ditellurofulvene) (Scheme 11). Addition of
PhTeBr to acetylenes has been reported earlier to afford an
E/Z mixture of bromo-vinylic tellurides in favor of the E isomer [27].
Our DFT quantum calculations for (E)-1,3-detellurofulvene 1
taken as zero, Z-1,3-detellurofulvene 3, appropriate 6-membered E/
Z-2,5-diiodo-1,4-ditellurines, and H-substituted model compounds
at PBE0/LANL2DZ(d) level have demonstrated higher thermody-
namic stability of 1,3-detellurofulvene 5-membered structure as
compared to 4- and 6-membered heterocycles 1aeb, 3aeb and
particularly, slightly higher thermodynamic stability of
1 as
compared to Z-isomer 3 (see Table 2).
Accordingly, DFTcalculations at the same level for Te-diodinated
Z-1,3-detellurofulvene 2 taken as zero, demonstrated its higher
thermodynamical stability among the all possible isomers 2aec
(see Table 3).
Fig. 1. Molecular structure of (E)-4-iodo-2-(iodo(phenyl)methylene)-5-phenyl-1,3-
ditellurole (1) showing thermal ellipsoids at the 50% probability level. Hydrogen atoms
are omitted for clarity.
Fig. 2. Molecular structure of (Z)-4-iodo-2-(iodo(phenyl)methylene)-5-phenyl-1
(diiodo),3-ditellurole (2) showing thermal ellipsoids at the 50% probability level.
Hydrogen atoms are omitted for clarity. Selected bond distances (Å): Te1-C2 2.058(11),
Te1-C10A 2.128(12), Te1-I1 2.9190(6), Te1-I2 2.9476(6), Te2-C1 2.110(10), Te2-C10A 2.119
(12), C1-C21.320(15), C10A-C20A 1.309(14) and bond angles (ꢁ): C2-Te1-C10A 93.1(5), I(1)-
Te(1)-I2 172.80(2), C1-Te2-C1A 112.4(7), C1-Te2-C10A 90.0(5), Te2-C10A-Te1 112.6(5).
Fig. 3. Molecular structure of(Z)-4-iodo-2-(iodo(phenyl)methylene)-5-phenyl-1,3-
ditellurole (3) showing thermal ellipsoids at the 50% probability level. Hydrogen atoms
are omitted for clarity. Selected bond distances (Å): Te2-C2 2.110(5), Te2-C4 2.110(5),
Te1-C5 2.112(5), Te1-C2 2.113(5), C1-C2 1.312(8), C4-C5 1.317(7) and bond angles (ꢁ):
C2-Te2-C4 89.9(2), C5-Te1-C2 93.4(2), Te2-C2-Te1 113.0(2).

500
Y. Torubaev et al. / Journal of Organometallic Chemistry 696 (2011) 496e503
Fig. 4. Packing pattern for 1. Intermol. d(Te1A-Te1(1 þ x, y. 1 þ z)) 3.881 Å (thermal ellipsoids at 50% probability level).
Fig. 5. 2-toluene-2 chains along the crystallographic c-axis. Intermolecular interaction distances (Å): Te1/toluene (x, y, z) C6-centroid 3.462, toluene C6-centroid/Te2(x, y, 1 þ z)
3.405 (thermal ellipsoids at the 50% probability level).
3. Experimental section
or purification. TLC plates were purchased from Merck (20 ꢂ 20 cm
silica gel 60 F254). Phenyliodoacetylene was prepared following
reported procedure [28].
3.1. General procedure
All reactions and manipulations were performed using standard
Schlenk line techniques under an inert atmosphere of purified
nitrogen. Solvents were purified, dried, and distilled under an argon
atmosphere prior to use. Infrared spectra for 1e3 were recorded on
a Nicolet 380 FT-IR spectrophotometer in a KBr pellets and NMR
spectra were recorded on aBruker Avanceiii 400 spectrometer in
DMSO. Commercial Te powder was used without further activation
3.2. Preparation of 1 and 2
A solution of phenyliodoacetylene 0.46 g (w2 mmol) was
refluxed in toluene (10 ml) with 0.25 g (w2 mmol) of finely ground
tellurium for 8 h under constant stirring on an oil-bath. Deep-red
reaction mixture was allowed to cool down slowly along with the
oil-bath without stirring to room temperature. Red-orange
Fig. 6. Toluene C6- centroid/Te distances: 3.518 Å in TeSb2Cl2(NtBu)4 [21]. 2.981 Å in [TeF4]n [22], 3.319 Å in [Te11N6Cl26] [23].

Y. Torubaev et al. / Journal of Organometallic Chemistry 696 (2011) 496e503
501
Cl
Concentration of the ethylacetate eluate with 20 ml of hexane
gave 2. Yield: 0.35 g (0.34 mmol), M.p. 118e122 ꢁC, IR (KBr, cmꢀ1):
1731.93(vs), 1592.42(w), 1572.64(w), 1480.94(s), 1437.94(s), 1H
Cl
Cl
S
S
Cl
NMR (d d,
, ppm): 7.941e7.340, 2.49 (CH3 of toluene) 13C NMR (
Se
Se
ppm): 29.081(CH3 of toluene), 80.76, 83.61, 121.78, 128.66 to 133.35
(Ph), 135.317.
Scheme 10. Rearrangement of transient 6-membered thiaselenane into thermody-
namically more stable 5-membered thiaselenolane [26].
Ph
Te
Ph
Ph
I
Ph
I
Te
Te
I
Te
Te
I
Te
I
I
Ph
I
Ph
Te
I
Ph
Ph
Te
Scheme 11. Possible mechanism of 1,3-detellurofulvene 1 formation.
crystalline precipitate was separated (0.63 g); its investigation
under the microscope showed that it consists of two types of well-
formed crystals: orange plates of 1 and deep-red prisms of 2 which
were used for single-crystal XRD analysis. The mother-liquor which
showed two orange bands on TLC (eluted with dichloromethane/
hexane 1:1 v/v) which were matching with crystalline samples of 1
and 2 from the first (precipitate) crop was evaporated to dryness
and separated by means of flash chromatography giving two frac-
tions after subsequent development with hexane and ethylacetate.
Concentration of the hexane eluate on the rotavapour gave 1.
Yield: 0.27 g (0.38 mmol) (37.7%), M.p. 124e126 ꢁC, IR (KBr, cmꢀ1):
3.3. Preparation of 3
For the preparation of 3, the ethylacetate fraction was shaken
with 10% aqueous sodium thiosulphate (100 ml) and subsequently
extracted with dichloromethane (3 ꢂ 50 ml), washed with brine
and dried over anhydrous sodium sulphate. Further concentration
of combined dichloromethane extracts with 50 ml of hexane and
cooling at ꢀ10 ꢁC overnight afforded 3 as orange-red crystals. Yield:
0.2 g (0.28 mmol).
M.p.105e110 ꢁC, IR (KBr, cmꢀ1): 1588.27(w),1572.64(w),1480.05
(s), 1438.10(w), 1H NMR ( , ppm): 7.924e7.335, 13C NMR (
d d, ppm):
1481.13, 1438.13(s), 1570.33(w), 1547.39 (w), 1H NMR (
7.950e7.316, 13C NMR (
, ppm): 80.70, 92.46, 122.981, 122.944,
d
, ppm):
80.67, 92.51, 122.963, 122.932, 128.100 to 133.213 (Ph), 135.024,
135.118. Mass spectrum of 3 shows molecular ion peaks centered at
m/e ¼ 713.67 (130Te) having the expected isotope pattern for Te2.
d
135.156, 135.057, 128.13 to 133.82 (Ph).
Table 1
Crystal data and structure refinement for 1e3.
Identification code
1
2
3
Empirical formula
Formula weight
Temperature, K
Wavelength
Crystal system
Space group
a, Å
C16H10I2Te2
711.24
293 (2)
C23H18I4Te2
1057.17
150 (2)
C16H10I2Te2
711.24
293 (2)
Mo (Ka
l
¼ 0.71073 Å)
Monoclinic
P21/n
Orthorhombic
Pmn2 (1)
13.3648 (5)
9.6185 (4)
10.3957 (4)
90.
1336.36 (9)
2
2.627
Monoclinic
C2/c
25.0469 (7)
10.2750 (2)
14.5386 (4)
113.273 (3)
3437.16 (15)
8
5.7173 (3)
23.4033 (10)
6.8514 (4)
110.241 (6)
860.13 (8)
2
2.746
6.969
632
b, Å
c, Å
ꢁ
b
,
Volume, Å3
Z
Density (calculated), Mg/m3
Absorption coefficient, mmꢀ1
F(000)
2.749
6.976
2528
6.812
944
Crystal size, mm3
0.33 ꢂ 0.26 ꢂ 0.21
0.09 ꢂ 0.05 ꢂ 0.04
0.20 ꢂ 0.10 ꢂ 0.07
q
range for data collection
3.29e29.00ꢁ.
3.26e29ꢁ.
3.45e29.00ꢁ.
Index ranges
Reflections collected
Independent reflections
ꢀ7ꢃhꢃ7,ꢀ31ꢃkꢃ31,ꢀ9ꢃlꢃ9
ꢀ16ꢃhꢃ18,ꢀ11ꢃkꢃ13,ꢀ14ꢃlꢃ13
12839
ꢀ34ꢃhꢃ34,ꢀ14ꢃkꢃ13,ꢀ19ꢃlꢃ11
15240
7827
2265 [R(int) ¼ 0.0523]
3567 [R(int) ¼ 0.0412]
4544 [R(int) ¼ 0.0279]
Completeness to
q
¼ 29ꢁ
99.0%
99.6%
99.5%
Absorption correction
Data/restraints/parameters
Refinement method
Semi-empirical from equivalents
3567/1/130
2265/0/107
4544/0/181
Full-matrix least-squares on F2
1.031
Goodness-of-fit on F2
0.818
1.350
Final R indices [I > 2sigma(I)]
R1 ¼ 0.0296
R1 ¼ 0.0260
R1 ¼ 0.0309
wR2 ¼ 0.0406
R1 ¼ 0.0566
wR2 ¼ 0.0546
wR2 ¼ 0.0733
R1 ¼ 0.0352
R indices (all data)
R1 ¼ 0.0293
wR2 ¼ 0.0426
wR2 ¼ 0.0553
wR2 ¼ 0.0745
Largest diff. peak and hole
1.280 and ꢀ0.901 e Åꢀ3
1.012 and ꢀ0.904 e Åꢀ3
2.117 and ꢀ1.029 e Åꢀ3

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Y. Torubaev et al. / Journal of Organometallic Chemistry 696 (2011) 496e503
Table 2
Relative potential energies, ZPVE corrected values () and relative standard enthalpies [ ]for 1, 3 and isomeric 6- and 4-membered heterocycles (in kcal/mol).
No.
Structure
R]Ph
R]H
No
Structure
R]Ph
R]H
No
Structure
R]Ph
R]H
I
R
R
I
Te
Te
R
I
I
Te
Te
Te
3.52
(3.65)
[4.13]
3.18
5.50
1
0.0
0.0
1a
1b
(3.23)
[3.3]
(5.54)
[6.38]
Te
R
R
R
I
I
R
R
I
R
I
Te
Te
I
Te
Te
I
Te
0.31
(0.26)
[0.32]
ꢀ0.13
(ꢀ0.17)
[0.48]
6.31
(6.35)
[6.20]
3.47
(3.71)
[4.04]
5.37
(5.62)
[6.01]
3
3a
3b
Te
R
R
I
R
Table 3
Relative potential energies, ZPVE corrected values () and relative standard enthalpies [ ] for H-substituted model compound for 2 and its isomers (R]H, in kcal/mol).
No.
Structure
No.
Structure
I
I
Te
Te
I
I
R
R
2(H)
0.0
2(H)b
1.59 (1.51) [1.53]
R
I
Te
I
Te
I
I
R
R
R
Te
Te
I
I
I
I
I
2(H)a
1.04 (0.89) [1.05]
2(H)c
2.31 (2.18) [2.29]
R
Te
I
Te
I
R
I
3.4. Crystal structure determination of 1e3
carbons C(1-10a)eC(2-20a) was stable so that constraining of
appropriate anisotropic displacement factors was not required.
The same procedure was used for the treatment of disorder
of carbon atom positions in 2. Non-hydrogen atoms were refined
with anisotropic thermal parameters. All hydrogen atoms were
geometrically fixed and refined using a riding model.
Relevant crystallographic data and details of measurements are
given in Table 1. X-ray crystallographic data were collected from
single-crystal samples of 1e3, mounted on an Oxford Diffraction
XCALIBUR-S CCD system equipped with graphite-monochromated
MoKa radiation (0.71070 Å). The data were collected by the u-2q
scan mode, and absorption correction was applied by using multi-
scan. The structure was solved by direct methods (SHELXS-97) and
refined by full-matrix least-squares against F2 using SHELXL-97
software [29]. Occupancies of the disordered carbon atom positions
in 1 were chosen so that as to satisfy the equality of according
isotropic displacement parameter (Uiso) values. However this was
not possible for the closely located phenyl carbons C(5)eC(8).
Subsequent anisotropic refinement of positions of vinylydenic
3.5. Computational details
Density functional theory (DFT)calculations of 1e3 and model
compounds (1aeb, 2aec, and 3aeb) were performed with PBE
hybrid exchange-correlation functional [30] using double-x valence
basis set [31,32] augmented with one polarization d-function for
main group elements [33] and one p-function for hydrogen atoms
[31]. The Hay and Wadt effective core potential (ECP) were used for

Y. Torubaev et al. / Journal of Organometallic Chemistry 696 (2011) 496e503
503
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Lett. 4 (1985) 13.
Te and I atoms [32]. Geometry optimization was performed without
constraints and optimized geometries were proven to be true
minimum by the Hessian matrix calculation. All calculations were
performed by using GAMESS-US [34] program package.
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Acknowledgments
We acknowledge the financial support from the Department of
Science and Technology, Government of India, and Russian Foun-
dation for Basic Research (grant 09-03-00961). Y.T. is also thankful
to Dr. F.M. Dolgushin (A.N. Nesmeyanov Institute of Organo-
Element Compounds, Moscow, Russia) for the fruitful discussion of
crystal structures of 1e3.
Appendix. Supplementary data
CCDC 771931 (1), CCDC 771932 (2), CCDC 771933 (3); contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk.
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(10e11) (2010) 1603e1608.
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Sulfur Silicon 172 (2001) 181e188.
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[29] G.M. Sheldrick, Acta Crystallogr. A64 (2008) 112.
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