Reactions of hybrid organotellurium ligands 1-(4-methoxyphenyl telluro)-2-[3-(6-methyl-2-pyridyl)propoxy]ethane (L1) and 1-ethylthio-2-[2-thienyltelluro]ethane (L2) with mercury (II) bromide: Formation of complexes and their decomposition

Article abstract of DOI:10.1016/j.ica.2004.10.021

Two tellurium ligands 1-(4-methoxyphenyltelluro)-2-[3-(6-methyl-2-pyridyl) propoxy]ethane (L¹) and 1-ethylthio-2-[2-thienyltelluro]ethane (L²) have been synthesized by reacting nucleophiles [4-MeO-C ₆H₄Te^-] and [C₄H₃S-2- Te^-] with 2-[3-(6-methyl-2-pyridyl)propoxy]ethylchloride and chloroethyl ethyl sulfide, respectively. Both the ligands react with HgBr ₂ resulting in complexes of stoichiometry [HgBr₂ ? L¹/L²] (1/4), which show characteristic NMR (¹H and ¹³C{¹H}). On crystallization of 1 from acetone-hexane (2:1) mixture, the cleavage of L¹ occurs resulting in 4-MeOC ₆H₄HgBr (2) and [RTe⁺→HgBr ₂]Br^- (3) (where R = -CH₂CH₂OCH ₂CH₂CH₂-(2-(6-CH₃-C ₅H₃N))). The 2 is characterized by X-ray diffraction on its single crystal. It is a linear molecule and is the first such system which is fully characterized structurally. The Hg-C and Hg-Br bond lengths are 2.085(6) and2.4700(7) ?. The distance of four bromine atoms (3.4041(7)-3.546(7) ?) around Hg (cis to C) is greater than the sum of van der Waal's radii 3.30 ?. This mercury promoted cleavage is observed for an acyclic ligand of RArTe type for the first time and is unique, as there appears to be no strong intramolecular interaction to stabilize the cleavage products. The 4 on crystallization shows the cleavage of organotellurium ligand L² and formation of a unique complex [(EtS(CH₂) ₂SEt)HgBr(μ-Br)Hg(Br)(μ-Br)₂Hg(Br)(μ-Br) BrHg(EtS(CH₂)₂SEt)] ? 2HgBr₂ (5), which has been characterized by single crystal structure determination and ¹H and ¹³C{¹H} NMR spectra. The elemental tellurium and [C₄H₃SCH₂]₂ are the other products of dissociation as identified by NMR (proton and carbon-13). The cleavage appears to be without any transmetalation and probably first of its kind. The centrosymmetric structure of 5 is unique as it has [HgBr ₃]^- unit, one Hg in distorted tetrahedral geometry and one in pseudo-trigonal bipyramidal one. The molecule of 5 may also be described as having [(EtSCH₂CH₂SEt)HgBr]⁺ [HgBr ₃]^- units, which dimerize and co-crystallize with two HgBr₂ moieties. There are very weak Hg?Br interactions between co-crystallized HgBr₂ units and rest of the molecule. [Hg(3)-Br(1)/Hg(3)-Br(4) = 3.148(1)/3.216(1) ?]. The bridging Hg?Br distances, Hg(2)-Br(4)′, Hg(2)′-Br(4) and Hg(1)-Br(2), are from 2.914(1) to 3.008(1) ?.

Full text of DOI:10.1016/j.ica.2004.10.021

Inorganica Chimica Acta 358 (2005) 912–918
www.elsevier.com/locate/ica
Reactions of hybrid organotellurium ligands 1-(4-methoxyphenyl
telluro)-2-[3-(6-methyl-2-pyridyl) propoxy]ethane (L1) and
1-ethylthio-2-[2-thienyltelluro]ethane (L2) with mercury (II) bromide:
formation of complexes and their decomposition
a
a
a,
b
Garima Singh , Sumit Bali , Ajai K. Singh *, John E. Drake ,
b
c
Charles L.B. Macdonald , M.B. Hursthouse , M.E. Little
c
a
Department of Chemistry, Indian Institute of Technology, New Delhi 110016, India
Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ont., Canada N9B 3P4
b
c
Department of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
Received 19 May 2004; accepted 17 October 2004
Available online 19 November 2004
Abstract
Two tellurium ligands 1-(4-methoxyphenyltelluro)-2-[3-(6-methyl-2-pyridyl)propoxy]ethane (L1) and 1-ethylthio-2-[2-thienyltel-
luro]ethane (L2) have been synthesized by reacting nucleophiles [4-MeO–C6H4Teꢀ] and [C4H3S-2-Teꢀ] with 2-[3-(6-methyl-2-pyr-
idyl)propoxy]ethylchloride and chloroethyl ethyl sulfide, respectively. Both the ligands react with HgBr2 resulting in complexes of
stoichiometry [HgBr2 ÆL1/L2] (1/4), which show characteristic NMR (1H and 13C{1H}). On crystallization of 1 from acetone–hexane
(2:1) mixture, the cleavage of L1 occurs resulting in 4-MeOC6H4HgBr (2) and [RTe+!HgBr2]Brꢀ (3) (where R =
–CH2CH2OCH2CH2CH2-(2-(6-CH3–C5H3N))). The 2 is characterized by X-ray diffraction on its single crystal. It is a linear molecule
˚
and is the first such system which is fully characterized structurally. The Hg–C and Hg–Br bond lengths are 2.085(6) and 2.4700(7) A.
˚
The distance of four bromine atoms (3.4041(7)–3.546(7) A) around Hg (cis to C) is greater than the sum of van der Waalꢀs radii 3.30
˚
A. This mercury promoted cleavage is observed for an acyclic ligand of RArTe type for the first time and is unique, as there appears to
be no strong intramolecular interaction to stabilize the cleavage products. The 4 on crystallization shows the cleavage of organotel-
lurium ligand L2 and formation of a unique complex [(EtS(CH2)2SEt)HgBr(l-Br)Hg(Br)(l-Br)2Hg(Br)(l-Br)BrHg(EtS(CH2)2SE-
1
t)]Æ2HgBr2 (5), which has been characterized by single crystal structure determination and H and 13C{1H} NMR spectra. The
elemental tellurium and [C4H3SCH2]2 are the other products of dissociation as identified by NMR (proton and carbon-13). The cleav-
age appears to be without any transmetalation and probably first of its kind. The centrosymmetric structure of 5 is unique as it has
[HgBr3]ꢀ unit, one Hg in distorted tetrahedral geometry and one in pseudo-trigonal bipyramidal one. The molecule of 5 may also be
described as having [(EtSCH2CH2SEt)HgBr]+ [HgBr3]ꢀ units, which dimerize and co-crystallize with two HgBr2 moieties. There are
very weak Hgꢁ ꢁ ꢁBr interactions between co-crystallized HgBr2 units and rest of the molecule. [Hg(3)–Br(1)/Hg(3)–Br(4) = 3.148(1)/
0
0
˚
˚
3.216(1) A]. The bridging Hgꢁ ꢁ ꢁBr distances, Hg(2)–Br(4) , Hg(2) –Br(4) and Hg(1)–Br(2), are from 2.914(1) to 3.008(1) A.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Tellurium ligands; 1-(4-Methoxyphenyltelluro)-2-[3-(6-methyl-2-pyridyl)propoxy]ethane; 1-Ethylthio-2-[2-thienyltelluro]ethane; Mercury
complexes; Decomposition; Crystal structures
*
Corresponding author. Tel.: +91 11 2659 1379; fax: +91 11 2686 2037/658 1037.
E-mail addresses: aksingh@chemistry.iitd.ac.in, ajai57@hotmail.com (A.K. Singh).
0020-1693/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.10.021

G. Singh et al. / Inorganica Chimica Acta 358 (2005) 912–918
913
1. Introduction
complexes and other decomposition products could not
be grown. The results of these investigations are re-
ported in the present paper.
In recent years, there has been growing interest in tel-
lurium ligands [1,2]. This is because there are increasing
evidences of enhanced ligating properties of telluroether
compared to thioethers, the availability of standardized
routes for synthesis of such ligands, the possibility of
using metal complexes of Te-ligands as precursor for
II–VI semiconductors, and the improved availability of
FT-NMR for studying behaviour in solution. Mer-
cury(II) is among the Lewis acids with which Te-donor
sites easily ligate. However, the cleavage of neutral
organotellurium ligands, viz. diorganyl tellurides has
been reported several times. The reaction of (2-(2-pyr-
idyl)phenyl)(3-ethoxyphenyl) tellurium (RR0Te) with
HgCl2 has resulted in [R0HgClÆ2RTeCl2] [3,4]. Bis[2-
(4,4-dimethyl-2-oxazolinyl)phenyl] telluride undergoes
C–Te bond cleavage on reaction with mercury (II) bro-
mide and it is attributed to the stabilizing effect of intra-
molecular N!Te interactions in the resulting products
[5]. [Pt(COD)2]Cl2 has also been found promoting cleav-
age of macrocyclic organotellurium ligands [6]. Re-
cently, for a palladium catalyzed Fujiwara-Heck cross
coupling reaction between organic tellurides and alke-
nes, migration of an organic moiety to Pd is proposed
as a key step [7,8].
2. Results and discussion
The reactions given in Scheme 1 result in L1, which
remains stable under ambient conditions for 3–4
months. The L1 has good solubility in chloroform and
dichloromethane but in methanol and hexane the solu-
bility was only moderate. Its reaction with HgBr2 and
decomposition of the mercury complex formed is also
shown in Scheme 1. The 1 is characterized by elemental
analyses and proton and carbon-13 NMR. In d10 sys-
tems, coordination shifts in NMR are not found to be
significant and this is true for 1 and 4 also. The 1H
NMR of 3 is also characteristic. The elemental analyses
support its stoichiometry. Such compounds are among
the expected ones in the tellurium chemistry [14]. The
1
2 shows characteristic H NMR and gives satisfactory
elemental analyses. The m(HgBr) in IR spectra of 2
and 3 has been observed at 294 cmꢀ1, as expected for
a terminal Hg–Br. The 3 is insoluble in organic solvents
non-polar in nature or having low polarity.Its single
crystals could not be grown.The compounds 1–3 are sta-
ble under ambient conditions and may be stored for 2–3
months easily. The 2 (Fig. 1) is the first example of linear
ArC–Hg–Br system (angle C–Hg–Br = 175.0(1)ꢁ) which
is fully characterized structurally [15]. The Hg atom is
surrounded by four more Br atoms in the crystal (mak-
ing nearly octahedral geometry), which are cis to aryl
carbon but the distances of all such atoms (3.4041(7)–
8
9
7
OMe
4
6
11
H3C
1
O
N
10
Te
5
3
2
L1
˚
3.546(7) A) are greater than the sum of van der Waalꢀs
˚
radii (3.30 A). The Hg–C distances of 2 (Table 2) are
6
7
˚
consistent with the literature report of 2.08 A for almost
linear Me–HgX [16]. Similarly, Hg–Br distance of 2 (Ta-
˚
ble 2) is consistent with the value of 2.480(3) A reported
for MeHgBr [16]. This mercury promoted cleavage is
observed for an acyclic ligand of RArTe type for the first
time and is unique, as there appears to be no strong
intramolecular interaction to stabilize the cleavage
products.
The ligand L2 was synthesized by reactions given in
Scheme 2. It is stable for 2 weeks only under ambient
conditions and is soluble in organic solvents such as
chloroform, dichloromethane and benzene but is very
poor in methanol solubility. The 1H and 13C NMR spec-
tra of L2 are characteristic. On reacting L2 with HgBr2, a
yellowish substance (small amount) is precipitated,
which is insoluble and defied all attempts of its charac-
terization. After filtering off this substance the mother
liquor was concentrated and mixed with hexane to ob-
tain 4, which on crystallization gives elemental tellurium
and single crystals of 5. The 6 was obtained from the
mother liquor. 4–6 show characteristic 1H and
5
4
CH3
1
S
8
Te
S
3
2
L2
In view of these observations, we have carried out reac-
tions of HgBr2 with newly synthesized 1-(4-methoxyphe-
nyl telluro)-2-[3-(6-methyl-2-pyridyl) propoxy]ethane
(L1) and 1-ethylthio-2-[2-thienyltelluro]ethane (L2). It
is observed that both these ligands first form complexes
having composition [HgBr2 ÆL1/L2], which decompose
during the attempt of growing single crystals resulting
in 4-MeOC6H4HgBr (2) in the case of L1 and
[(EtS(CH2)2SEt)HgBr(l-Br)Hg(Br)(l-Br)2Hg(Br)(l-Br)
BrHg(EtS(CH2)2SEt)]Æ2HgBr2 (5) in the case of L2.
Both 2 and 5 have been characterized by X-ray diffrac-
tion on their single crystals. The structure of 5 is unique
and most probably is the first example of this type.
Other products of these decompositions have also been
identified. However, the single crystals of both mercury

914
G. Singh et al. / Inorganica Chimica Acta 358 (2005) 912–918
-
N2
,
atm
BH4
-
L1
+
4-MeOC6H4Te
[4-MeOC6H4Te]2
EtOH, Reflux
N
H3C
CH2CH2CH2OCH2CH2Cl
r.t
[HgBr2.L1] (1)
HgBr2 + L1
(acetone) (CHCl3)
crystallization from acetone-hexane (2:1)
HgBr
[RTe+ HgBr ]
-
MeO
Br
+
2
(2)
(3)
8
9
7
6
4
11
1
O
H3C
N
10
= R
CH2
5
3
2
Scheme 1.
Te, o
THF
C
Br(2)–Hg(2)–Br(4) and Br(3)–Hg(2)–Br(4) (115.19(5)–
122.20(5)ꢁ) which are very close to 120ꢁ expected for
[HgBr3]ꢀ anion [19–21]. Thus, 5 can be described as hav-
ing [(EtSCH2CH2SEt) HgBr]+[HgBr3]ꢀ units which
dimerize and co-crystallize with two HgBr2 moieties
resulting in the structure shown in Fig. 2. The cleavage
of L2 in its Hg(II) complex resulting in 5 most probably
occurs as shown in Scheme 3. So far, this kind of cleav-
age has never been reported for diorganyl tellurides.
Generally, reverse transmetalation or transmetalation
has been made responsible for cleavage of organotellu-
rium ligands in their complexes. Therefore, the present
one is the first example of the type where cleavage occurs
without any kind of transmetalation.
N
2
ClCH2CH2SEt
THF, -78 oc
L2
TeLi
S
S
Li
N2
24 h
HgBr2
4
3
[HgBr2.L2]
1
S
Crystallized from
5 + Te +
5
4
CHCl3-hexane(1:1)
S 2
6
Scheme 2.
13C{1H} NMR. Single crystal structure of 5 has been
determined and Fig. 2 shows ORTEP diagram. In the
structure of 5, bond angles reveal that Hg(1) has dis-
torted tetrahedral geometry and Hg(3) pseudo-trigonal
bipyramidal geometry. The Hg(2)—Br (1) distance
3.451(1) A is greater than the sum of van der Waalꢀs ra-
˚
dii 3.30.A. The Hg—S distances (2.612(3) and 2.523(3)
˚
A) in 5 are longer than the values reported in the litera-
˚
ture 2.340 (2)–2.40(1) A [17–19]. There are three types of
3. Experimental
˚
The C and H analyses were carried out with a Perkin–
Elmer elemental analyzer 240 C. Tellurium was esti-
1
mated by atomic absorption spectrometer. The H and
Hg—Br distances in 5. Among the long ones, Hg(2)–
13C{1H} NMR spectra were recorded on a Bruker Spec-
trospin DPX-300 NMR spectrometer at 300.13 and
75.47 MHz, respectively. IR spectra in the range 4000–
Br(4)0 = 3.008(1); Hg(2)0–Br(4) = 3.008(1) and Hg(1)–
˚
represent the weak bridging
Br(2), = 2.914(1)
A
interactions (or secondary), whereas Hg(3)–Br(1) =
˚
3.148(1) and Hg(3)–Br(4) = 3.216(1) A show further
250 cmꢀ1 were recorded on a Nicolet Protege 460
´
weak secondary interactions. Hg(1)–Br(1), Hg(2)–
Br(3), Hg(2)–Br(2), Hg(2)–Br(4), Hg(3)–Br(5) and
Hg(3)–Br(6) bond distances are between 2.417(1) and
.
CH3
S
.
˚
CH2SEt
+
2.573(1) A and consistent with the values reported for
Te
L2
S
TeCH2
S
˚
single covalent bond 2.480(3) A [16]. The closeness of
Hg(2)–Br(3), Hg(2)–Br(2) and Hg(2)–Br(4) distances
indicates that Hg(2) is a part of [HgBr3]ꢀ ion, which is
also supported by bond angles Br(2)–Hg(2)–Br(3),
6 + Te
EtSCH2CH2SEt
Scheme 3.

G. Singh et al. / Inorganica Chimica Acta 358 (2005) 912–918
915
FT-IR spectrometer as KBr and CsI pellets. Far IR
spectra in the range 500–100 cmꢀ1 were recorded in
polyethylene on Perkin–Elmer spectrometer 1700X.
The melting points determined in open capillary are re-
ported as such.
and were refined using the WinGX version [12] of
SHELX-97 [13]. All of the non-hydrogen atoms were trea-
ted anisotropically. Hydrogen atoms were included in
idealized positions with isotropic thermal parameters
set at 1.2 times that of the carbon atom to which they
were attached. The final cycle of full-matrix least-
squares refinement for 2 was based on 1913 observed
reflections (1537 for F2 > 4r(F2)) and 93 variable param-
eters and converged (largest parameter shift was 0.001
times its esd). The final cycle of full-matrix least-squares
refinement for 5 was based on 4372 observed reflections
(3744 for F2 > 4r(F2)) and 156 variable parameters and
converged (largest parameter shift was 0.001 times its
esd). The relatively high residual peaks are not unusual
in view of the slab-like shape of the small crystal of 5
combined with the presence of so many heavy atoms.
Selected distances and bond angles for 2 and 5 are given
in Tables 2 and 3, respectively. The molecules 2 and 5
are displayed as an ORTEP diagram in Figs. 1 and 2,
respectively. Additional material available from the
Cambridge Crystallographic Data Centre comprises
the final atomic coordinates and thermal parameters
for all atoms, and a complete listing of bond distances
and angles.
3.1. X-ray diffraction analysis
A colourless block crystal of CH3OC6H4HgBr, 2, was
mounted on a glass fibre, covered in Paratone–N, and
placed rapidly into the cold N2 stream of the Kryo-Flex
low temperature device. A hemisphere of data was col-
lected on a Bruker APEX CCD diffractometer using a
counting time of 20 s per frame. Data reduction was per-
formed using the SAINT software [9] and the data were
corrected for Lorentz, polarization and absorption ef-
fects using the SAINT and SADABS programs. Cell refine-
ment gave cell constants corresponding to an
orthorhombic cell, whose dimensions are given in Table
1 along with other experimental parameters. A colour-
less, slab crystal of [(EtS(CH2)2SEt)HgBr2Hg(Br)Br2-
Hg(Br)Br2Hg
(EtS(CH2)2SEt)]Æ2HgBr2
(5)
was
mounted on a glass fibre. Data were collected on an En-
raf–Nonius Kappa CCD area detector diffractometer,
with /- and x-scans chosen to give a complete asymmet-
ric unit. Cell refinement [10] gave cell constants corre-
sponding to a triclinic cell whose dimensions are given
in Table 1 along with other experimental parameters.
An absorption correction was applied [10]. The struc-
tures of 2 and 5 were solved by direct methods [11]
3.2. Synthesis of 2-[3-(6-methyl-2 pyridyl)propoxy]
ethylchloride
A solution of 2-[3-(6 methyl-2 pyridyl)propoxy] etha-
nol (3.15 g, 16 mmol) in dry chloroform was cooled in
Table 1
Crystal data and structure refinement for 2 and 5
Empirical formula
Formula weight
Temperature (K)
C7H7OBrHg
387.63
173(2)
C12H28Br12Hg6S4
2463.04
120(2)
˚
Wavelength (A)
0.71073
0.71073
triclinic
Crystal system
Space group
˚
a/b/c (A)
orthorhombic
Pbca
6.7989(3)/6.9342(3)/35.456(2)
ꢀ
P1
9.3682(4)/10.6672(5)/11.1783(4)
a/b/c (ꢁ)
90 (all)
1671.6(1)
62.414(2)/79.026(3)/84.561(2)
971.95(7)
3
˚
Volume (A )
Z
8
3.081
1
4.208
Dcalc (g/cm3)
Absorption coefficient (mmꢀ1
F(000)
Crystal size (mm3)
)
23.124
1376
36.163
1064
0.40 · 0.30 · 0.30
2.30–27.52
0.20 · 0.10 · 0.02
3.08–27.52
h range for data collection (ꢁ)
Index ranges
ꢀ8 6 h 6 8, ꢀ9 6 k 6 9, ꢀ46 6 l 6 46
14707
1913 (0.0471)
ꢀ12 6 h 6 12, ꢀ13 6 k 6 13, ꢀ14 6 l 6 13
19675
4372 (0.1153)
Reflections collected
Independent reflections (Rint
)
Maximum and minimum transmission
Refinement method
0.0547 and 0.0389
full-matrix least squares on F2
1913/0/93
0.5316 and 0.0520
full-matrix least-squares on F2
4372/0/156
Data/restraints/parameters
Goodness-of-fit on F2
1.147
1.062
Final R indices [F2 > 4r(F2)]
R indices (all data)
Largest difference peak and hole (e A )
R1 = 0.0278, wR2 = 0.0637
R1 = 0.0345, wR2 = 0.0662
1.145 and ꢀ2.388
R1 = 0.0588, wR2 = 0.1640
R1 = 0.0711, wR2 = 0.1732
3.962 and ꢀ4.840
3
˚

916
G. Singh et al. / Inorganica Chimica Acta 358 (2005) 912–918
Table 2
a
˚
Selected bond lengths (A) and angles (ꢁ) for 2
Hg(1)–Br(1)0
Hg(1)–Br(1)000
Br(1)–Hg(1)–C(1)
2.4700(7)
3.4041(7)
3.4214(7)
175.0(1)
Hg(1)–C(1)
Hg(1)–Br(1)00
Hg(1)–Br(1)0000
2.085(6)
3.4133(7)
3.546(7)
Hg(1)–Br(1)
Br(1)–Hg(1)–Br(1)0
Br(1)–Hg(1)–Br(1)000
86.08(2)
82.84(2)
Br(1)–Hg(1)–Br(1)00
Br(1)–Hg(1)–Br(1)0000
85.88(2)
89.16(2)
a
Symmetry equivalent position (ꢀ1/2 + x,3/2 ꢀ y,ꢀz) given by a
prime, (1/2 + x,3/2 ꢀ y,ꢀz) by a double prime, (1 ꢀ x,2 ꢀ y,ꢀz) by a
triple prime, and (1 ꢀ x,1 ꢀ y,ꢀz) by a quadruple prime.
Fig. 1. ORTEP plot of the molecule CH3OC6H4HgBr (2). The atoms
are drawn with 50% probability ellipsoids.
idyl)propoxy]ethylchloride made in 10 cm3 of ethanol
was added and the mixture was refluxed for 2–3 h. It
was cooled to room temperature and poured into
100 cm3 of water. Ligand L1 from aqueous phase was
extracted into 100 cm3 of chloroform. The extract was
dried over anhydrous sodium sulfate. The chloroform
was evaporated under reduced pressure to give ligand
Table 3
˚
Selected bond lengths (A) and angles (ꢁ) of 5
Hg(1)–Br(1)
Hg(2)–Br(3)
Hg(2)–Br(4)
Hg(2)0–Br(4)
Hg(1)–S(1)
2.492(1)
2.537(1)
2.551(1)
3.008(1)
2.612(3)
2.417(1)
3.148(1)
Hg(1)–Br(2)
Hg(2)–Br(2)
Hg(2)–Br(4)0
Hg(2)–Br(1)
Hg(1)–S(2)
2.914(1)
2.573(1)
3.008(1)
3.451(1)
2.525(3)
2.425(1),
3.216(1)
Hg(3)–Br(5)
Hg(3)–Br(1)
Hg(3)–Br(6),
Hg(3)–Br(4)
I
L1 as yellow viscous oil. Yield: 70%. H NMR (CDCl3,
25 ꢁC): d (vs TMS): 1.91–2.01 (m, 2H, H4), 2.52 (s, 3H,
H11), 2.71–2.82 (t, 2H, H1), 2.95–3.0 (t, 2H, H5), 3.43–
3.47 (t, 2H, H3), 3.66–3.70 (t, 2H, H2), 3.78 (s, 3H,
OCH3), 6.73–6.76 (d, 2H, m to Te), 6.93–6.96 (2s, 2H,
H7 and H9), 7.43–7.48 (t, 1H, H8), 7.65–7.70 (d, 2H, o
to Te); 13C{1H}NMR (CDCl3, 25 ꢁC): d (vs TMS):
8.16 (C1), 24.14 (C11), 28.91 (C4), 54.78 (OCH3), 69.48
(C2), 71.85 (C3), 99.81 (ArTe–C), 114.83 (C9), 119.37
(ArC m to Te), 120.19 (C7), 136.44 (C8), 140.62 (ArC
o to Te), 157.35 (C10), 160.52 (ArC p to Te), 161.15 (C6)
Br(1)–Hg(1)–S(1)
S(1)–Hg(1)–S(2)
125.20(8)
86.57(10)
91.86(8)
115.19(5)
121.51(5)
98.87(4)
79.26(4)
83.16(4)
179.07(5)
92.86(4)
88.70(4)
Br(1)–Hg(1)–S(2)
Br(1)–Hg(1)–Br(2)
S(2)–Hg(1)–Br(2)
Br(3)–Hg(2)–Br(4)
Br(2)–Hg(2)–Br(4)0
Br(4)–Hg(2)–Br(4)0
Br(3)–Hg(2)–Br(1)
Br(4)0–Hg(2)–Br(1)
Br(5)–Hg(3)–Br(1)
Br(5)–Hg(3)–Br(4)
Br(1)–Hg(3)–Br(4)
146.55(8)
92.03(4)
97.61(8)
122.20(5)
96.99(4)
85.07(4)
97.44(4)
163.28(4)
87.70(4)
92.14(4)
78.80(3)
S(1)–Hg(1)–Br(2)
Br(3)–Hg(2)–Br(2)
Br(2)–Hg(2)–Br(4)
Br(3)–Hg(2)–Br(4)0
Br(2)–Hg(2)–Br(1)
Br(4)–Hg(2)–Br(1)
Br(5)–Hg(3)–Br(6)
Br(6)–Hg(3)–Br(1)
Br(6)–Hg(3)–Br(4)
Symmetry equivalent position (ꢀx + 1,ꢀy + 1,ꢀz + 1) represented by
a prime.
3.4. Synthesis of [HgBr2 ÆL1] (1)
To a solution of HgBr2 (0.20 g, 0.55 mmol) made in
acetone (20 ml) was added a freshly prepared solution
of L1 (0.22 g, 0.55 mmol) in chloroform (20 ml). The
resulting mixture was stirred at room temperature until
the ligand L1 was consumed (as monitored by TLC).
The solvent was removed from the mixture on a rotary
evaporator. The resulting residue was dissolved in
20 ml of chloroform and filtered through Celite. The fil-
trate was concentrated to 10 ml and mixed with 20 ml of
hexane. A white complex was filtered, dried in vacuo
and recrystallized from chloroform–hexane (1:1) mix-
ture. Yield: 80%. M.p., 130 ꢁC (d). Anal. Calc. for
C18H23NO2TeHgBr2: C, 27.97; H, 2.97; N, 1.81; Te,
16.50. Found: C, 27.12; H, 2.91; N, 1.76. Te, 16.31%.
IH NMR (CDCl3, 25 ꢁC): d (vs TMS): 1.86–1.89 (m,
2H, H4), 2.46 (s, 3H, H11), 2.71–2.75 (t, 2H, H1), 3.37
(t, 2H, H5), 3.46-(bs, 2H, H3), 3.65–3.68 (m, 5H, H2
and OCH3), 6.74–6.77 (d, 2H, m to Te), 6.93–6.97 (m,
2H, H7 and H9), 7.47–7.52 (t, 1H, H8), 7.68–7.71
(d,2H, o to Te); 13C{1H} NMR (CDCl3, 25 ꢁC): d (vs
TMS): 24.81 (C11), 28.91 (C4), 34.86 (C1), 55.29
(OCH3), 66.91 (C2), 70.44 (C3), 99.81 (ArTe–C),
114.78 (C9), 116.22 (ArC m to Te), 120.98 (C7), 137.12
an ice bath. Thionyl chloride (2.80 g, 23.5 mmol) dis-
solved in dry chloroform was added to it dropwise over
a period of 0.5 h. The mixture was stirred in ice bath for
20 min and heated thereafter over steam bath for 2 h.
The deep red coloured solution was washed with satu-
rated bicarbonate solution and water successively. The
organic layer separated, dried over MgSO4 and evapo-
rated on a rotary evaporator to give 2-[3-(6-methyl-2
pyridyl)propoxy]ethylchloride as a deep red oil. Yield:
I
76%. H NMR (CDCl3, 25 ꢁC): d (vs TMS): 1.97–2.06
(p, 2H, H4), 2.53 (s, 3H, H11), 2.82–2.87 (t, 2H, H5),
3.51–3.53 (t, 2H, H3), 3.59–3.63 (t, 2H, H2), 3.63–3.68
(t, 2H, H1), 6.96–6.99(2s, 2H, H7 and H9), 7.46–7.51
(t, 1H, H8).
3.3. Synthesis of 1-(4-methoxyphenyl telluro)-2-[3-(6-
methyl-2-pyridyl)propoxy]ethane (L1)
Bis(4-methoxyphenyl)ditelluride (1 g, 2.13 mmol) was
refluxed in ethanol (50 ml) under dry nitrogen atmos-
phere. Sodium borohydride (0.20 g) dissolved in 2 ml
of 1 M NaOH was added dropwise until the solution be-
came colourless. A solution of 2-[3-(6-methyl-2 pyr-

G. Singh et al. / Inorganica Chimica Acta 358 (2005) 912–918
917
Fig. 2. ORTEP plot of 5, the non-hydrogen atoms are drawn with 50% probability ellipsoids.
(C8), 139.31(ArC o to Te), 157.35 (C10), 160.52 (ArC p
to Te), 161.15 (C6).
mixture was stirred overnight at room temperature
and poured into 100 ml of cold water. The ligand
was extracted into 100 ml chloroform from the aque-
ous phase. The extract was washed with distilled water
and dried over anhydrous Na2SO4. On evaporating off
solvent under reduced pressure on a rotary evaporator,
L2 was obtained as a red viscous liquid. Yield: 80%.
Anal. Calc. for C8H12S2Te: Te, 42.59. Found: Te,
3.5. Synthesis of 2 and 3
The [HgBr2 ÆL1] (1) (0.07 g) was dissolved in acetone–
hexane (2:1) mixture and kept for slow evaporation at
25 ꢁC. After 7 days, crystals of 2 were obtained. The
mother liquor was mixed with 20 ml of CHCl3 and ref-
luxed for 3 h. The 3 was obtained as solid. It was fil-
tered, washed with CHCl3 and dried in vacuo.
2: Yield: ꢂ18%. Anal. Calc. for C7H7OHgBr: C, 27.70;
H, 1.80. Found: C, 27.71; H, 1.82%. NMR (IH CDCl3, 25
ꢁC): d (vs TMS): 3.71 (s, 3H, OCH3), 6.89–6.91 (d, 2H,
ArH m to Hg), 7.34–7.37 (d, 2H, ArH o to Hg).
3: Yield: ꢂ18%. M.p. 143–144 ꢁC (d). Anal. Calc. for
C11H16OTeNHgBr3: C, 17.70; H, 2.10; N, 1.87. Found:
C, 17.30; H, 2.01; N, 1.82%. NMR (1H, DMSO-d6, 25
ꢁC): d (vs TMS):1.82–1.84 (t, 2H, H4), 2.35 (s, 3H,
H11), 2.66–2.81 (m, 2H, H5), 3.63–3.68 (m, 2H, H2),
3.75–3.81(m, 2H, H1), 7.02–7.11 (m, 2H, H7 + H9),
7.68–7.78 (m, 1H, H9); H3 merged with signal of water
in DMSO.
1
42.36%. H NMR(CDCl3, 25 ꢁC): d (vs TMS): 1.17–
1.22 (t, 3H, H1), 2.48–2.55 (m, 2H, H4), 2.92–2.99
(m, 4H, H2 and H3), 6.90–6.93 (dd, 1H, H7), 7.37–
7.38 (d, 1H, H6) 7.42–7.44 (d, 1H, H8). 13C{1H}
NMR (CDCl3, 25 ꢁC): d (vs TMS): 10.4 (C4), 14.5
(C1), 25.2 (C2), 33.1 (C3), 119.3 (C6), 134.2 (C8),
141.8 (C7), 142.7 (C5).
3.7. Synthesis [HgBr2 ÆL2] (4)
A freshly prepared solution of L2 (0.19 g, 0.55 mmol)
in chloroform (20 ml) was added to a solution of HgBr2
(0.20 g, 0.55 mmol) made in acetone (20 ml). The yellow
coloured precipitate (small amount) formed instantane-
ously was filtered off and the resulting filtrate was stirred
at room temperature until the ligand L2 was consumed
(as monitored by TLC). The solvent was removed from
the mixture on a rotary evaporator resulting in the com-
plex 4, which was washed with hexane and dried in va-
cuo. Yield: ꢂ30%. 1H NMR (CDCl3, 25 ꢁC,): d (vs
TMS): 1.26–1.30 (m, 3H, H1), 2.56–2.68 (m, 2H, H4),
2.78–2.85 (m, 4H, H2 and H3), 7.14–7.16 (bm, 1H,
H7), 7.40–7.42 (m, 1H, H6) 7.73 (bs, 1H, H8). 13C{1H}
NMR (CDCl3, 25 ꢁC): d (vs TMS): 10.0 (C4), 14.0
(C1), 26.8 (C2), 30.95 (C3), 128.8 (C6), 134.4 (C8),
139.2 (C5), 140.6 (C7).
3.6. Synthesis of 1-ethylthio-2-[2-thienyltelluro]ethane
(L2)
Tellurium powder (0.65 g, 5 mmol) suspended in
20 ml of THF was mixed with 5 ml of 1 mM solution
of thienyl lithium (5 mmol) in THF at 0 ꢁC. The mix-
ture was stirred for 2 h under nitrogen atmosphere and
a solution of chloroethyl ethyl sulfide (5 mmol) made
in 5 ml of THF was added to it dropwise at ꢀ78 ꢁC
with constant stirring under nitrogen atmosphere. The

918
G. Singh et al. / Inorganica Chimica Acta 358 (2005) 912–918
3.8. Synthesis of [(EtS(CH2)2SEt)HgBr(l-Br)Hg(Br)
(l- Br)2Hg(Br)(l-Br)BrHg (EtS(CH2)2SEt)]Æ 2HgBr2
(5) and (6)
03/EMR-II and fellowship to GS. M.B.H. thanks the
UK Engineering and Physical Sciences Council for
support of the X-ray facilities at Southampton.
J.E.D. thanks the University of Windsor for financial
support. C.L.B.M. thanks the Natural Sciences and
Engineering Research Council of Canada for financial
support.
The [HgBr2 ÆL2] (0.1 g) was dissolved in 20 ml of chlo-
roform and filtered through Celite. The filtrate was con-
centrated to 10 ml and mixed with 20 ml of hexane. With
the evaporation of hexane, white crystals of 5 were ob-
tained. They were dried in vacuo. The mother liquor
of this crystallizing solution was concentrated to 10 ml
on a rotary evaporator and mixed with hexane (20
ml), which resulted in 6 which was washed with hexane
and dried in vacuo.
5: Yield: 20%. Anal. Calc. for C6H14Hg3S2Br6: C,
5.84, H, 1.13. Found: C, 5.80, H, 1.04%. 1H NMR
(CDCl3, 25 ꢁC): d (vsTMS): 1.32–1.36 (t, 3H, H1),
2.76–2.84 (q, 2H, H2), 2.93 –3.03 (m, 2H, H3);
13C{1H} NMR (CDCl3, 25 ꢁC): d (vs TMS): 14.6 (C1),
26.15 (C2), 31.00.(C3).
References
[1] (a) A.K. Singh, V. Srivastava, J. Coord. Chem. 27 (1992) 237;
(b) A.K. Singh, S. Sharma, Coord. Chem. Rev. 209 (2000) 49;
(c) A.K. Singh, Proc. Indian Acad. Sci. (Chem. Sci.) 114 (2002)
357.
[2] (a) E.G. Hope, W. Levason, Coord. Chem. Rev. 12 (1993) 109;
(b) W. Levason, D. Orchard, G. Reid, Coord. Chem. Rev. 225
(2002) 159;
(c) J.A. Barton, A.R.J. Genge, N.J. Hill, W. Levason, S.D.
Orchard, B. Patel, G. Reid, A.J. Ward, Heteroatom Chem. 13
(2002) 550.
6: Yield: ꢂ20%. Anal. Calc. for C10H10S2C, 61.85, H,
1
5.15, Found: C, 60.31, H, 5.01. H NMR (CDCl3, 25
[3] S.A. Mbobo, W.R. McWhinnie, T.S. Lobana, Inorg. Chim. Acta
193 (1992) 5.
ꢁC): d (vs TMS): 2. 38– 2.44 (d, 4H, H1), 7.24–7.31
(m, 2H, H4), 7.41–7.51 (m, 4H, H3 and H5); 13C{1H}
NMR (CDCl3, 25 ꢁC): d (vs TMS): 21.04 (C1), 127.25
(C3), 129.92 (C4), 136. 12 (C5), 142.23 (C2).
[4] S.A. Mbobo, W.R. McWhinnie, T.S. Lobana, Inorg. Chim. Acta
172 (1990) 221.
[5] S.D. Apte, S.S. Zade, H.B. Singh, R.J. Butcher, Organometallics
22 (2003) 5473.
[6] S.C. Menon, A. Panda, H.B. Singh, R.J. Butcher, Chem.
Commun. (2000) 143.
[7] Y. Nishibayashi, C.S. Cho, S. Uemura, J. Organomet. Chem. 507
(1996) 197.
4. Conclusions
[8] Y. Nishibayashi, C.S. Cho, K. Ohe, S. Uemura, J. Organomet.
Chem. 526 (1996) 335.
1-(4-Methoxyphenyltelluro)-2-[3-(6-methyl-2-pyridyl)
propoxy]ethane (L1) and 1-ethylthio-2-[2-thienyltel-
luro]ethane (L2) have been synthesized. Only very few
ligands having thienyl group linked to tellurium are
known and therefore the synthesis of L2 is significant.
The decomposition of mercury complexes of both the
ligands during crystallization indicates the intricate
behaviour of mercury when associated with tellurium
ligands. The 4-MeOC6H4HgBr (2) is fully characterized
by X-ray diffraction. The [(EtS(CH2)2SEt)HgBr
(l-Br)Hg(Br)(l-Br)2Hg(Br)(l-Br)BrHg(EtS(CH2)2SEt)].
2HgBr2 (5) is also characterized by X-ray diffraction and
is a unique complex, which is probably first example of
this type.
[9] SAINT-2001, Bruker AXS, Inc. Madison, WI, USA.
[10] Z. Otwinowski, W. Minor, DENZO data collection and process-
ing software, in: C.W. CarterJr., R.M. Sweet (Eds.), Macromo-
lecular Crystallography, Part A, Methods in Enzymology, vol.
276, Academic Press, London, 1997, pp. 307–326.
[11] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
[12] L.J. Farrugia, J. Appl. Cryst. 32 (1999) 837.
[13] SHELXL97, G.M. Sheldrick, University of Gottingen, Germany.
[14] N.G. Dance, C.H.W. Jones, J. Organomet. Chem. 152 (1978)
175.
[15] V.I. Pakhomov, Zh. Struktur. Khim. 5 (1964) 873.
[16] A. Iverfeldt, I. Persson, Inorg. Chim. Acta 111 (1986) 171.
[17] D. Matkovic-Calogovic, D. Mrvos-Sermek, Z. Popovic, Z. Soldin,
Acta Crystallogr, Sect. C C60 (2004) m44.
[18] N. Davidovic, D. Matkovic-Calogovic, Z. Popovic, D. Vedrina-
Irena, Acta Cryst., Sect C: Cryst. Struct. Commn. C54 (1998) 574.
[19] W.J. Kozarek, F. Quintus, Inorg. Chem. 12 (1973) 2129.
[19] S. Walha, J.M. Savariault, J. Jaud, A. Ben Salah, Phys. Chem.
News 8 (2002) 69.
Acknowledgements
[20] I. Pabst, J.W. Bats, H. Fuess, Acta Crystallogr., Sect B 46 (1990)
503.
AKS, SB and GS thank the Council of Scientific
and Industrial Research (India) for project 01(1849)/
[21] H. Terao, M. Hashimoto, S. Hashimoto, Y. Furukawa, Z.
Naturforsch., Phys. Sci. 55 (2000) 230.