1. Synthesis, molecular structures, M€ossbauer and electrochemical
investigation of ferrocenyltelluride derivatives: (Fc2Te2)Fe(CO)3I2
[(CO)3IFe(m-TeFc)]2, CpFe(CO)2TeFc, CpFe(CO)2TeX2Fc (X ¼ Br, I) and
CpFe(CO)2(m-TeFc)Fe(CO)3I2
Yury V. Torubaev a, *
, Alexander A. Pasynskii a
, Alina V. Pavlova a
, Mohd Tauqeer b
,
Rolfe H. Herber c
, Israel Nowik c
, Ivan V. Skabitskii a
, Gleb L. Denisov a
, Vitaly A. Grinberg e
,
Pradeep Mathur d
, Mobin M. Shaikh d
, Goutam K. Lahiri b
a
N.S. Kurnakov Institute of General and Inorganic Chemistry RAS, Moscow, Russia
b
Chemistry Department, Indian Institute of Technology, Powai, Mumbai, India
c
Racah Institute of Physics, The Hebrew University, 91904 Jerusalem, Israel
d
School of Basic Sciences, Indian Institute of Technology Indore, India
e
A.N. Frumkin Institute of Physical Chemistry & Electrochemistry RAS, Moscow, Russia
a r t i c l e i n f o
Article history:
Received 26 October 2014
Received in revised form
21 November 2014
Accepted 22 November 2014
Available online 13 December 2014
Keywords:
Metal-chalcogenide
Ferrocenyl
Organotellurium
X-ray diffraction
Electrochemistry
M€ossbauer spectroscopy
a b s t r a c t
Depending on the ratio of the starting reagents, the interaction of [FcTeI] with Fe(CO)5 gave complex
(Fc2Te2)Fe(CO)3I2 (1) bearing an Fc2Te2 ligand, or a dimeric complex [(CO)3IFe(m-TeFc)]2 (2). An inter-
action of equimolar amounts of [CpFe(CO)2]2 and Fc2Te2 under the thermal conditions in toluene
afforded CpFe(CO)2TeFc (3). Complex 3 can be easily halogenated at the Te center by elemental bromine
and iodine to give monomeric CpFe(CO)2TeX2Fc (X ¼ Br (4), I (5)). Complex 5 can be prepared alterna-
tively via formal insertion of [FcTeI] into FceI bond of CpFe(CO)2I. Complex 3 readily substitutes one
carbonyl in Fe(CO)4I2 to give the adduct CpFe(CO)2(m-TeFc)Fe(CO)3I2 (6).
© 2014 Elsevier B.V. All rights reserved.
Introduction
Transition metal tellurides can be obtained by pyrolysis of
organotellurium complex precursors incorporating the desired el-
ements in the required ratio. The solid state structures of the pre-
cursors could be determined by XRD techniques and such
compounds are generally stable in organic solvents, allowing them
to be deposited on the various supporting materials. For example
the deposition of cluster (C8H12)PtTe2Fe2(CO)6 from CH2Cl2 on
Ketjen Black Carbon and subsequent pyrolysis at 300 С, followed
by elimination of cyclodiene and four CO molecules to give the
composition PtTe2Fe2(C)2(O)2, which is a methanol-tolerant
nano-sized catalyst for oxygen reduction in the direct methanol
fuel cell [1].
We have obtained various inorganic transition metal tellurides
starting from transition metal carbonyls with bridging and terminal
diphenylditellurium or phenyltelluride ligands.
In the presence of the aromatic fragments in the molecule, we
do not observe the formation of carbides and oxides during the
thermolyses. For example, all carbonyl groups in the Mo/Ph2Te2
complex are eliminated so that ТеeТе and TeePh bonds of Ph2Te2
ligands are cleaved to give polymeric cubane Mo4Te4 clusters,
which can be subsequently transformed to the known monomeric
anionic cyanide cluster [2] (Scheme 1).
Substitution of the phenyl group for ferrocenyl group should
have some interesting consequences. Firstly, this led us to introduce
* Corresponding author. Tel.: þ7 495 9543841.
E-mail address: torubaev@igic.ras.ru (Y.V. Torubaev).
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
http://dx.doi.org/10.1016/j.jorganchem.2014.11.025
0022-328X/© 2014 Elsevier B.V. All rights reserved.
Journal of Organometallic Chemistry 777 (2015) 88e95

2. additional iron atoms into a molecule of the precursor. Secondly,
the electron-donating ferrocenyl fragment increases the nucleo-
philicity of the associated tellurium atom. Finally, the ferrocenyl
group can be easily oxidized electrochemically or by oxidative
agents. Our recent investigation of diferrocenyleditelluride com-
plexes of VI group carbonyls demonstrated general similarity with
their phenyl congeners, particularly the electron-compensating
cleavage of the TeeTe bond during the photochemical decarbon-
ylation (Scheme 2) [3] (Fig. 1).
It was also interesting to compare the reactivity of [FcTeI] to-
wards Fe(CO)5 with that of its phenyl congener [PhTeI] [4] and
investigate the decarbonylation of CpFe(CO)2TeFc and of its use as a
possible metalloligand.
Results and discussion
Depending on the ratio of the starting reagents an interaction
between FcTeeTeI2Fc and Fe(CO)5 gives the monomeric complex
(Fc2Te2)Fe(CO)3I2 (1) or the dimeric complex [(CO)3IFe(m-TeFc)]2 (2)
if an excess of Fe(CO)5 was used (Scheme 3):
In complex 1 the molecule of diferrocenylditelluride is coordi-
nated only by one tellurium atom completing the octahedral co-
ordination surrounding of the iron atom. The ironetellurium
distance is shortened (Te1eFe1 2.580(1) Å) as compared to the CRS
(2.70 Å) [5], similarly to the rest of known transition metal
organotellurides. This shortening is usually rationalized in terms of
additional back donation М / Te [6] and is accompanied by the
consequent elongation of the TeeTe distance (2.770(1) Å as
compared to 2.704e2.721 Å in a “free” Fc2Te2 [7,8]. It is interesting
that in 1 the “dropping” of Te(2) atom from the cyclopentadienyl
plane to the iron atom of the ferrocenyl fragment takes place
(a ¼ 11.8). In the dimeric complex 2 (Fig. 2), iodide and bridging
telluroferrocenyl ligands were found at the same (as in 1) distances
from the iron centers. The same similarity we have noticed in the
pair of their phenyl congeners: (CO)3FeI2(Ph2Те2) and [(CO)3IFe-
TePh]2 [9].
Complex CpFe(CO)2TeFc 3 (Fig. 3) containing the terminal fer-
rocenyltelluride ligand instead of the iodine atom was obtained as a
brown crystalline product of the thermal interaction between
[Ср(CO)2Fe]2 and Fc2Te2, by analogy with the preparation of
CpFe(CO)2TePh [10].
In 3 the FeeТе distance (2.589(3) Å) is significantly longer as
compared to that in CpFe(CO)2TePh (FeeTe 2.528 Å), since the
additional Fe / Te back donation is reduced because an electron
withdrawing phenyl is substituted for electron donating ferrocenyl
group.
The cyclic voltammogram (CV) for complex 3 (Fig. 4, curve 1)
demonstrates a quasi-reversible one-electron oxidation wave at
0.24 V apparently, arising from the ferrocenyl fragment oxidation,
and the quasi-reversible two-electron oxidation wave at 0.76 V,
Scheme 1. Formation and thermolyses of Ph2Te2 complexes of Mo-carbonyls.
Scheme 2. Formation and transformation of Fc2Te2 e complexes of Cr-, Mo- and W-carbonyls.
Y.V. Torubaev et al. / Journal of Organometallic Chemistry 777 (2015) 88e95 89

3. arising from the oxidation of the tellurium and the second iron
atoms.
Being treated with the elemental bromine or iodine, complex 3
easily attaches two halogen atoms at the tellurium center so that
the FeeTe bond remains untouched (Scheme 4). The structures of
Fig. 1. The solid state structure of 1 in the thermal ellipsoids at the 50% probability
level. Due to the disorder carbon atoms of Cp-rings where refined in isotropic model
and are shown as spheres. Hydrogen atoms are omitted for clarity. Selected intra-
molecular distances (Å):Te1eTe2 2.770(1), Te1eFe1 2.580(1), Fe1eI1 2.660(2), Fe1eI2
2.648(2); and angles (): CpeTe2 168.20, CpeTe1 176.78.
Fig. 2. The solid state structure of 2 in thermal ellipsoids at the 50% probability level.
Because of the disorder carbon atoms of Cp-rings are shown as spheres. Hydrogen
atoms are omitted for clarity. Selected intramolecular distances (Å): Fe1eTe 2.5965(5),
FeeI 2.6452(6).
Fig. 3. The solid state structure of 3 in thermal ellipsoids at the 50% probability level.
Due to the disorder carbon atoms of Cp-ring at Fe1 where refined in isotropic model
and are shown as spheres. Hydrogen atoms are omitted for clarity. Selected intra-
molecular distances (Å): Fe1eTe1 2.591(2).
Scheme 3. Formation of 1 and 2.
Fig. 4. The cyclic voltammogram (CV) for complex 3 (curve 1) and for complex 5
(curve 2).
Scheme 4. Formation of 3e5.
Y.V. Torubaev et al. / Journal of Organometallic Chemistry 777 (2015) 88e9590

4. corresponding dihalides CpFe(CO)2TeХ2Fc, Х ¼ Br and I (4 and 5
respectively) were determined by XRD method (Figs. 5 and 6):
The CV diagram for the complex 5 (Fig. 4, curve 2) contains a
quasi-reversible one-electron oxidation wave at 0.75 V, arising
from the ferrocenyl fragment oxidation, and a quasi-reversible one-
electron oxidation wave at 0.98 V, arising from the oxidation of the
second iron atom in the CpFe(CO)2 moiety.
Similarly to its phenyl congener, CpFe(CO)2TePh, complex 3 can
be used as a metal-containing building block in a design of the
complex metal-chalcogene frameworks. For example, 3 can coor-
dinate a Fe(CO)3I2 fragment to give CpFe(CO)2(m-TeFc)Fe(CO)3I2 (7)
which incorporates three iron atoms in different coordination
surrounding (Scheme 5, Fig. 7).
In complexes 4, 5, 6 the Fe1eТе1 distances (2.522(2), 2.5328(6),
2.5574(11) Å) are significantly shorter as compared to the starting
complex 3 (FeeTe 2.591(2) Å). This effect can be rationalized in
terms of the electron density withdrawal from Te atom and
consequent increase of the Fe / Te back donation from CpFe(CO)2
moiety. It is supported by Mossbauer data for complex 6.
In order to more completely characterize the properties of
compound 6 a M€ossbauer effect (ME) study was undertaken over
the temperature range 96 T 300 K. A representative spectrum
is shown in Fig. 8 from which it is evident that the three iron sites
are clearly resolved from each other. For the purposes of the
present discussion and in consonance with the numbering scheme
in Fig. 7, the Fe atom ligated to the Cp and two CO groups is
referred to as Fe1, the Fe atom of the ferrocene fragment is
referred to as Fe2, and the Fe atom ligated to two I and three CO
groups is referred to as Fe3. Fe1 and Fe3 atoms are directly bonded
to the central Te atom. Each of these three Fe resonances has a
well resolved isomer shift (IS) and quadrupole splitting (QS) as
will be discussed below.
The IS and QS parameters at 90 K are summarized in Table 1
from which it is seen that Fe1 and Fe3 have similar IS values,
while that of Fe2 (0.494 ± 0.012 mm sÀ1
) is close to that reported
for the parent ferrocene (0.537 ± 0.001 mm sÀ1
) as expected.
The temperature-dependence of the IS for Fe2 is well fitted by a
linear regression (R ¼ 0.98 for 11 data points) which, in turn leads
[11] to a value of Meff ¼ 127 ± 4 Da. The difference between this
value and the “bare” Fe mass is a measure of the covalency of the
Fe-to-ligand bonding. On the other hand the QS parameter is only
slightly sensitive to T and has a mean value of 2.425 ± 0.008 mm sÀ1
again similar to that of ferrocene at 90 K.
The temperature dependence of the logarithm of the area under
the resonance curve, which scales with the temperature-
dependence of the recoil-free fraction (f) is again well fitted by a
linear regression (R ¼ 0.997 for 10 data points) and will be dis-
cussed in more detail, below.
Fig. 5. The solid state structure of 4 in thermal ellipsoids at the 50% probability
level. Hydrogen atoms are omitted for clarity. Selected intramolecular distances
(Å): Fe1eTe1 2.522(2), Te1eBr2 2.712(2), Te1eBr1 2.768(2) Å, Fe2eTe1 3.713(3) Å.
Fig. 6. The solid state structure of 5 in thermal ellipsoids at the 50% probability
level. Hydrogen atoms are omitted for clarity. Selected intramolecular distances
(Å): Fe1eTe1 2.5328(6), Te1eI2 2.9855(4), Te1eI1 2.9420(4), Te1eFe2 3.6911(9) Å.
Scheme 5. Formation of 6.
Fig. 7. The solid state structure of 6 showing its associates in thermal ellipsoids at the
50% probability level. Hydrogen atoms are omitted for clarity. Selected intramolecular
distances (Å): Fe1eTe1 2.5574(11), Fe3eTe1 2.6381(11), Fe3eI3 2.5978(16), Fe3eI2
2.6533(11), Fe3eI1 2.677(2), Te1eC11 2.120(7) Å.
Y.V. Torubaev et al. / Journal of Organometallic Chemistry 777 (2015) 88e95 91

5. The IS and QS parameters for Fe1 and Fe3 are quite similar, as
noted from table and the temperature dependence of QS is essen-
tially temperature insensitive over the accessible range. There is,
however, a significant difference in d IS/dT for these two atoms
(5.95 ± 0.94 and 3.44 ± 0.88 Â 10À4
mm sÀ1
KÀ1
) respectively,
leading to Meff values of 67 ± 7 and 121 ± 25 Da for the two sites
with the latter presumably reflecting the influence of the two
massive iodine atom in the structure.
As has been pointed out earlier [12], the temperature depen-
dence of the recoil-free fraction can be related to the root-mean-
square-amplitude-of-vibration of the metal atom and compared
to the corresponding value extracted from the Ui,j parameters of the
single-crystal X-ray determination of 6. The temperature-
dependence of ln[A(T)/A(90)] for Fe2 is summarized graphically in
Fig. 9 and has a slope of (6.20 þ 0.060) Â 10À3
KÀ1
with a corre-
lation coefficient of 0.996 for 11 data points. The line has an
intercept (at T ¼ 0 K) of 0.595.
These data can be converted to the Ғ parameter (¼exp
k2
xave
2
) by adding 0.959 and extrapolation to T ¼ 0 K, making the
assumption that the zero-point contribution to the vibrational
amplitude in the ME temperature regime is negligible. The result-
ing Ғ values are summarized graphically in Fig. 10.
As noted above, the Ғ parameter can also be calculated from the
X-ray data, as shown in Fig. 10 and as noted, the agreement is quite
satisfactory. A similar sequence of data reductions has been ob-
tained for Fe1 and Fe3 of compound 6 and in general there is good
agreement between the Ғ values calculated from the ME data and
the single crystal X-ray data. From the Ғ values it is possible to
calculate the rmsav of the metal atom at all temperatures in the
accessible range, and this is shown in Fig. 11.
From this figure it will be noted that the temperature-
dependence of the rmsav of Fe2 of 6 is quite similar to that of
ferrocene, the small difference being presumably due to the ligation
of this moiety to the central Te atom. On the other hand, the rmsav
data of Fe1 and Fe3 of 6 (represented by the filled red (in the web
version) data points) are quite similar and significantly smaller than
the corresponding data for Fe2 reflecting a tighter binding of Fe1
and Fe3 than Fe2 in the compound 6. These data are also consistent
with the interatomic distance measurements extracted from the
single crystal X-ray data at 296 K and DFT simulated IS and QS
parameters for iron atoms in 6 (Table 2).
Conclusion
Although the introduction of the ferrocenyl group instead of the
phenyl group in the telluride compounds does not change signifi-
cantly the chemical properties and structures of the complexes, it
provides an opportunity to oxidize the ferrocenyl group in a one-
electron quasi-reversible process. The interaction of FcTeI with
Fig. 8. 57
Fe M€ossbauer spectrum of compound 6. The three Fe sites are assigned to Fe1
(blue), Fe2 (green) and Fe3 (red) following the notation of the single crystal X-ray
assignments. The hyperfine parameters (IS and QS), their temperature dependencies,
and the associated dynamical parameters are summarized in Table and further dis-
cussed in the text. (For interpretation of the references to color in this figure legend,
the reader is referred to the web version of this article.)
Fig. 9. The temperature-dependence of d ln(A(T)/A(90)]/dT for the Fe2 atom of com-
pound 6.
Table 1
Summary of the ME and related parameters for compound 6. The parenthetical
values are the errors in the last significant figure(s). The quadrupole parameters (QS)
are not temperature sensitive in the range 96 T 300 K of the ME measurements.
Fe1 Fe2 Fe3
IS(90) 0.187 (18) 0.494 (12) 0.148 (13) mm sÀ1
QS(90) 1.694 (14) 2.425 (8) 0.441 (9) mm sÀ1
Àd IS/dT 5.9 (10) 3.29 (10) 3.44 (88) Â10À4
mm s1
KÀ1
Àd ln [A(T)/A(90)] 4.95 (17) 6.20 (6) 11.54 (17) Â10À3
KÀ1
Meff 67 (7) 127 (4) 121 (25) Daltons
k2
xave
2
, X, 296 1.585 (8) 1.814 (9)
Fig. 10. The Ғ parameter for the Fe2 site of compound 6. The ME data are indicated by
the open data points, the value extrapolated to 0 K by the starred data point, and the
value calculated from the single crystal X-ray data by the filled data point.
Y.V. Torubaev et al. / Journal of Organometallic Chemistry 777 (2015) 88e9592

6. Fe(CO)5 proceeds as an oxidative addition, giving monomeric
(Fc2Te2)Fe(CO)3I2 and a dimeric complex [(CO)3IFe(m-TeFc)]2 .
CpFe(CO)2TeFc can substitute one CO group in Fe(CO)4I2 to give the
adduct CpFe(CO)2(m-TeFc)Fe(CO)3I2 and can then easily be haloge-
nated at the Te center by elemental bromine and iodine to give
monomeric CpFe(CO)2TeX2Fc (X ¼ Br or I). Alternatively the same
type of complexes arise when [FcTeI] is formally inserted into the
FceI bond of CpFe(CO)2I.
Experimental part
General procedure
All reactions and manipulations were performed using standard
Schlenk techniques under an inert atmosphere of pure nitrogen or
argon. Solvents were purified, dried and distilled under a nitrogen
atmosphere prior to use. Commercial Fe(CO)5, [CpFe(CO)2]2, I2, Br2
were used without additional purification. CpFe(CO)2I and
Fe(CO)4I2 were prepared following the reported procedure [13].
Diferrocenylditellurium (Fc2Te2) was prepared by a slightly modi-
fied procedure [14].
1
H, 13
C and 125
Te NMR spectra were recorded on Varian VXR-
300S and Bruker AVANCE III/400 spectrometer in CDCl3 with TMS
or Ph2Te2 as standards respectively at 293e295 K. Infrared spectra
were recorded on a Perkin Elmer FT-IR spectrometer as hexane
solutions in 0.1 mm path length NaCl cells. TLC plates were pur-
chased from Merck (20 Â 20 cm silica gel 60 F254).
Electrochemistry
The cyclic voltammograms (CV) of complexes 3 and 5 were
recorded on a PAR 273 potentiostat/galvanostat (Princeton Applied
Research) with the standard software. The measurements were
carried out in a thermostatically controlled three-electrode elec-
trochemical cell under a high purity argon atmosphere. An SU-2000
(0.0078 cm2
) glassy carbon disk pressed in Teflon served as the
working electrode and a platinum grid (1 cm2
) was used as the
auxiliary electrode. The potentials were measured versus the silver
reference electrode in the same solution. The measurements were
carried out in dichloromethane with 0.2 M Bu4NPF6 as the sup-
porting electrolyte. The potential sweep rates were in the range
from 0.050 to 1.0 V sÀ1
.
M€ossbauer spectroscopy
The samples were transferred into plastic sample holders and
mounted in a variable-temperature cryostat as described previ-
ously [15]. The methods for spectrometer calibration, data analysis,
and temperature control monitoring have been detailed previously
[15]. All isomer shifts (IS) are given with respect to a room-
temperature a-Fe absorber spectrum which was also used for
spectrometer calibration. The ME spectral line widths for the
optically “thin” samples was 0.248 ± 0.013 mm sÀ1
DFT calculations
The M€ossbauer parameters were calculated at the DFT level of
theory using the ORCA program [16]. Scalar relativistic effects were
treated by the ZORA approximation [17,18]. Hybrid meta-GGA
functional TPSSh [19] was used with triple-z all electron relativ-
istic basis set recontracted for use with ZORA approximation (TZVP)
[20]. Isomer shifts were calculated from the electron density at
nuclei using a linear dependence d ¼ a(r À C) þ b with parameters
determined in Ref. [21]. Geometry of more populated isomer of
complex 7 was taken from XRD data and positions of hydrogen
atoms or all geometry parameters were optimized at TPSS [22]/
TZVP level of theory.
Synthesis of (CO)3FeI2(Fc2Te2) (1)
To the orange solution of Fc2Te2 (50 mg, 0.08 mmol) in CH2Cl2
(8 ml) violet solution of I2 (0.02 g, 0.08 mmol) in CH2Cl2 (3 ml) was
added and stirred for 30 min at 0 C. The resulting crimson-red
reaction mixture was treated with Fe(CO)5 (0.01 ml, 0.08 mmol)
and stirred for 3.5 h at 0 C, till the band of starting Fe(CO)5 dis-
appeared in the IR spectra. The reaction mixture was concentrated
with 2.5 ml of hexane (approx. to ½ of starting volume) filtered
and left for 24 h at À5 C to give a black prismatic crystalline
precipitate suitable for XRD study. Crystals were filtered off,
washed with hexane and dried in vacuum. An additional amount
of product was obtained from the dried mother-liquor. Yield:
0.038 g (47.5%)
IR spectra (KBr, nCO, cmÀ1
): 2079s, 2031s, 2026s.
Found (%): C 26.28H 1.94. For Fe3Te2I2H18O3C23 (Mr ¼ 1019)
Calc (%): C 27.11H 1.78
Synthesis of [(CO)3FeI(m-FcTe)]2 (2)
To the solution of diferrocenylditelluride (78 mg, 0.125 mmol)
and an equimolar amount of Iodine (I2) (0.032 g, 0.125 mmol) in
THF (10 mL), Fe(CO)5 (0.15 ml, 0.125 mmol) was added at room
temperature. The reaction mixture was stirred for 30 min. The
solvent was removed in vacuo, the residue was dissolved in
dichloromethane and subjected to chromatographic work-up using
TLC plates. Elution with a dichloromethane/hexane mixture
(20:80 v/v) gave Fc2TeI2 and 2. The single crystals of 2 suitable for
Fig. 11. The root-mean-square-amplitudes-of-vibration of the three Fe atoms in
compound 6 of the text. The data for Fe1 and Fe3 are essentially identical and differ
significantly for the values for Fe2. The comparison with the data for ferrocene (Fc) are
indicated by the filled black data points.
Table 2
Calculated IS and QS parameters for iron atoms in complex 6. Parameters calculated
for fully optimized geometry are given in parentheses.
Fe1 Fe2 Fe3
d, mm/s 0.10 (0.08) 0.48 (0.44) 0.05 (0.01)
DEQ, mm/s 1.69 (1.68) 2.41 (2.21) 0.18 (À0.29)
Y.V. Torubaev et al. / Journal of Organometallic Chemistry 777 (2015) 88e95 93

7. XRD investigation were obtained by recrystallization from CH2Cl2//
hexane mixture.
IR spectra (THF, nCO, cmÀ1
): 2057s, 2012s
Synthesis of CpFe(CO)2TeFc (3)
Red-brown mixture of 0.25 g (0.7 mmol) [CpFe(CO)2]2 and
0.44 g (0.7 mmol) Fc2Te2 in toluene (30 ml) was stirred at 100 C for
1 h. The resulting yellow-brown solution was filtered under argon,
concentrated under reduced pressure to 1/3 of its initial volume
and kept at À10 C for 24 h to provide a brown crystalline precip-
itate which contained crystals suitable for single-crystal X-ray
analysis. The crystals were decanted, washed with cold heptane
(2 Â 5 ml) and dried in vacuum. Yield: 0.6 g (87%)
Found (%): C 42.50H 3.05 For C17H24Fe2O2Te (Mr ¼ 489)
Calc. (%): C 41.70H 2.88.
IR spectrum (KBr; nCO, cmÀ1
): 1997, 1952.
1
H NMR (400 MHz, CDCl3) d 4.11 (m.br., 2H, C5H4Te), 4.18 (s, 5H,
C5H5), 4.29 (m.br., 2H, C5H4Te), 4.80 (s, 5H, C5H5). 13
C{H}
(100.6 MHz, CDCl3) 34.40, 70.00, 70.74, 80.15, 84,57, 215.31; 125
Te
NMR (126.2 MHz, CDCl3) d À407.7 (s, TePh).
Synthesis of CpFe(CO)2TeBr2Fc (4)
0.053 ml of Br2 was added to the stirred brown solution of 0.05 g
(0.1 mmol) CpFe(CO)2TeFc in CH2Cl2 (8 ml). The resulting red re-
action mixture was stirred at ambient temperature for 20 min and
filtered under argon. 2 ml of hexanes was added to the filtrate and
concentrated under reduced pressure to 1/2 of its initial volume
and kept at À10 C for 24 h to yield a red crystalline precipitate
which contained crystals suitable for single-crystal X-ray analysis.
Crystals were decanted, washed with cold heptane (2 Â 5 ml) and
dried in vacuum. Yield: 0.054 g (82%)
Found (%): C 31.477H 2.73. For CpFe(CO)2TeBr2Fc (Mr ¼ 650)
Calc. (%): C 31.44, H 2.17
IR spectrum (KBr; n, cmÀ1
): 2044, 1997.
Synthesis of CpFe(CO)2TeI2Fc (5)
a) To a solution of [FcTeI] formed at room temperature by
the reaction of diferrocenylditelluride, Fc2Te2 (78 mg,
0.125 mmol) with the equimolar amount of solid I2 (0.032 g,
0.125 mmol) in toluene (20 mL), cyclopentadienyliron dicar-
bonyl iodide [CpFe(CO)2I] (0.038 g, 0.125 mmol) was added.
The temperature was raised to 50
C and the reaction mixture
was stirred for 2 h. The mother liquor was decanted and the
dark-red precipitate was washed with hexane (15 ml) and
dried in vacuum. The single crystals suitable for XRD inves-
tigation were obtained by recrystallization from CH2Cl2//
hexane mixture.
Yield: 46 mg (49%).
b) The purple solution 0.025 g (0.1 mmol) of I2 in CH2Cl2 (2 ml) was
added to the stirred brown solution of 0.05 g (0.1 mmol)
CpFe(CO)2TeFc in CH2Cl2 (6 ml). The resulting red-brown reac-
tion mixture was stirred at ambient temperature for 30 min and
filtered under argon. 1.5 ml of hexanes was added to the filtrate,
concentrated under reduced pressure to 1/2 of its initial volume
and kept at À10
C for 24 h to provide a dark-red crystalline
precipitate which contained crystals suitable for single-crystal
X-ray analysis. Crystals were decanted, washed with cold hep-
tane (2 Â 5 ml) and dried in vacuum. Yield: 0.069 g (91%)
Found (%): C 27.73H 1.42 For CpFe(CO)2TeI2Fc (Mr ¼ 743)
Calc. (%): C 27.46H 1.89
IR spectrum (CH2Cl2; nCO, cМÀ1
): 2044, 2007.
Synthesis of CpFe(CO)2(m-TeFc)Fe(CO)3I2 (6)
At room temperature, a solution of 0.086 g (0.2 mM) Fe(CO)4I2 in
5 ml CH2Cl2 was added dropwise to the stirred solution of 0.1 g
(0.20 mM) CpFe(CO)2TeFc in 10 ml of CH2Cl2. The brown reaction
mixture was filtered, 2.5 ml of hexane was added and its volume
was reduced by 1/2 in vacuum. Being kept for 24 h at À10 C it
produced brown crystalline precipitate, containing crystals suitable
for single crystal XRD study, was decanted, washed with heptane
(2 Â 5 ml), and dried in vacuum.
Yield: 0.15 g (83%)
Found (%): C 27.57H 1.78 For C20H14O5Fe3TeI2 (Mr ¼ 883)
Calc. (%): C 27.20H 1.60.
IR spectra (KBr, n, cmÀ1
): 2072s, 2026s, 2008w, 1981w
Crystal structure determinations of compounds 1e6
Relevant crystallographic data and the details of measurements
for 1e6 are given in the online supplementary.
A Bruker APEX II CCD area detector diffractometer and CCD
Agilent Technologies (Oxford Diffraction) SUPER NOVA using
graphite-monochromated Mo Ka radiation (0.71070 Å) were used
for the cell determination and intensity data collection for com-
pounds 1, 3, 4, 6 and 2, 5 respectively.
The data were collected by the standard phi-omega scan tech-
niques, and were scaled and reduced using Bruker (for 1, 3, 4, 6) and
CrysAlisPro RED (for 2, 5) software packages.
Structures were solved by direct methods and refined by full-
matrix least squares (F2
) using SHELXL-97 [23] software. Except
for the carbon atoms of the disordered ferrocenyl Cp-rings in 1e3,
positions of non-hydrogen atoms were refined with anisotropic
thermal parameters. All hydrogen atoms were geometrically fixed
and refined using a riding model.
Acknowledgments
We gratefully acknowledge the financial support from the
Department of Science and Technology (DST, India), University
Grants Commission (UGC, India), Russian Foundation for Basic
Research (12-03-00860 and 13-03-92691), Department of Chem-
istry and Material Sciences of RAS (grant OKh 1.3), Presidium of RAS
(grant 8P23).
Appendix A. Supplementary material
CCDC nos. 1029846, 1029850, 1029851, 1029852, 1029853,
1029854 contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
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