Synthesis, characterization, and computational study of some new organotellurium compounds containing azomethine groups

Article abstract of DOI:10.1002/hc.20437

The reaction of ortho-mercurated anilines with benzaldehyde gave the ortho-mercurated Schiff bases. The reaction of the mercurated Schiff bases with tellurium tetrabromide in 1:1 and 2:1 mole ratio using dry chloroform as solvent gave the ortho-tellurated

Full text of DOI:10.1002/hc.20437

Heteroatom Chemistry
Volume 19, Number 3, 2008
Synthesis, Characterization, and
Computational Study of Some New
Organotellurium Compounds Containing
Azomethine Groups
Ali Z. Al-Rubaie,1 Wasfi A. Al-Masoudi,2 Shaker A. N. Al-Jadaan,3
Abraham F. Jalbout,4 and Ali Jameel Hameed1
1Department of Chemistry, College of Science, University of Basrah, Basrah, Iraq
2Department of Chemistry, College of Arts and Science, Tarhona, Almergab University,
P.O. Box 48211, Tarhona, Libya
3Department of Chemistry, College of Pharmacy, University of Basrah, Basrah, Iraq
4Department of Chemistry, University of Arizona, Tucson, AZ 85721
Received 17 October 2006; revised 21 June 2007
ꢀ
C
age.
2008 Wiley Periodicals, Inc. Heteroatom Chem
ABSTRACT: The reaction of ortho-mercurated ani-
lines with benzaldehyde gave the ortho-mercurated
Schiff bases. The reaction of the mercurated Schiff
bases with tellurium tetrabromide in 1:1 and 2:1
mole ratio using dry chloroform as solvent gave
the ortho-tellurated Schiff bases compounds ArTeBr3
and Ar2TeBr2, respectively, in good yields (where
Ar = 5-ClC6H3N CHC6H5, 5-BrC6H3N CHC6H5, 5-
CH3OC6H3N CHC6H5, and 5-NO2C6H3N CHC6H5).
The reduction of ArTeBr3 by hydrazine hydrate gave
the corresponding ditelluride (i.e., Ar2Te2). Treatment
of Ar2TeBr2 with hydrazine hydrate afforded tellurides
(Ar2Te) in good yields. Attempts to prepare the cor-
responding aryl tellurenyl bromides, ArTeBr, by par-
tial reduction of ArTeBr3 with various reducing agents
were unsuccessful. All these new compounds were
characterized by microanalysis, 1H, and 13C NMR, IR,
and mass spectroscopic data. A computational study
for the Te → N interactions of all compounds was
calculated using the GAUSSIAN 03 program pack-
19:307–315, 2008; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/hc.20437
INTRODUCTION
Direct telluration of Schiff bases by tellurium tetra-
halides resulted in formation of ionic products,
arising from hydrolysis of tellurium tetrahalides
[1–3]. Mercuration of Schiff bases followed by
a trans-metallation reaction with tellurium tetra-
bromide provided a satisfactory method to pre-
pare [4-methoxy-2-(phenyliminomethyl)phenyl] tel-
lurium tribromide in 42% yield, which on re-
duction gave the stable tellurium(II) derivative
in 30% yield [3]. The mercurated Schiff bases
also reacted with p-ethoxyphenyl tellurium trichlo-
ride to produce the corresponding dichloride
[3], namely, (4-ethoxyphenyl)[4-methoxy-2-(phenyl-
iminomethyl)-phenyl] tellurium dichloride, in 70%
yield [3].
Sadekov et al. [4–8] made considerable con-
tributions to the chemistry of tellurated azome-
thines, and several tellurated Schiff bases were
Correspondence to: Ali Z. Al-Rubaie; e-mail: alrubaie49@
yahoo.com.
2008 Wiley Periodicals, Inc.
c
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307

308 Al-Rubaie et al.
TABLE 1 Some Physical and Analytical Data for Compounds 1–14
Analysisa
H
Compound
Color
Yellow
Yellow
Yellow
Brown
Yellow
Yellow
Yellow
M.P. (◦C)
Yield (%)
C
N
ν(C
N)
1
137–139
155–157
39–141
83
75
72
80
52
65
77
74
64
60
52
45
73
76
26.42 (26.81)
24.74 (24.93)
28.73 (29.01)
25.92 (26.35)
43.24 (43.57)
46.78 (47.04)
47.46 (47.51)
41.97 (42.32)
45.31 (45.60)
43.42 (42.32)
54.04 (54.31)
47.98 (48.34)
57.68 (57.57)
51.12 (51.39)
1.39 (1.45)
1.47 (1.59)
1.94 (2.07)
1.38 (1.53)
2.48 (2.53)
2.96 (3.04)
3.21 (3.42)
2.37 (2.46)
2.51 (2.63)
2.39 (2.57)
3.43 (3.51)
2.51 (2.78)
4.03 (4.41)
3.26 (3.38)
2.16 (2.40)
2.06 (2.23)
2.11 (2.42)
4.3 (4.73)
1555s
1560s
1553s
1545s
1535s
1555s
1559s
1554s
1557s
1552s
1550s
1560s
1545s
1548s
2
3
4
171–173
137–139
174–176b
112–114b
172–174
122–124
134–136
202–204
184–186
163–165
149–151
5
3.59 (3.91)
3.85 (4.22)
3.92 (3.96)
7.27 (7.59)
3.76 (4.09)
7.65 (7.59)
4.55 (4.87)
4.02 (4.33)
3.98 (4.79)
9.06 (9.40)
6
7
8
Yellow
9
Orange
Red-brown
Pale Yellow
Yellow
Yellow
Yellow
10
11
12
13
14
aCalculated values are given in parentheses.
bDecomposed.
prepared and characterized [4–8]. The ability of
β-bromotellurenylvinylaldehydes [8–11] and mono-
halotellurobenzaldehydes [12] to form Schiff bases
enabled this methodology to synthesize a wide range
of organotellurium compounds containing CH N
groups [12]. Such compounds were used as precur-
sors or proposed as intermediates for the synthesis
of heterocyclic tellurium compounds, such as 5H-
1.2-oxatelluroles and their benzo analogs, isotellura-
zoles, 1,2,3-telluradiazines, 1,2,6-oxatellurazocines,
and other related tellurium heterocycles [8]. Molec-
ular structures of some of these tellurated azome-
thines in the solid state indicated the existence of
the intramolecular Te ← N bond [5,6,12–15].
decided to use these mercurated anilines as precur-
sors to prepare a new series of mercurated Schiff
bases, from which a number of hitherto unavailable
organotellurium compounds containing azomethine
groups were prepared.
RESULTS AND DISCUSSION
Synthesis
Isolated yields, melting points, color and carbon,
hydrogen, and nitrogen analytical data for all new
organotellurium compounds are given in Table 1.
The present work describes the synthesis of new tel-
lurated Schiff bases by reaction of the correspond-
ing mercurated Schiff bases, which in turn prepared
from the reaction of aryl mercury chloride with ben-
zaldehyde, with tellurium tetrabromide in 1:1 ratio
to produce the required tellurium containing mate-
rials (ArTeBr3), that is, compounds 1–4 (Scheme 1).
On the other hand, when tellurated Schiff bases and
tellurium tetrabromide brought together in 2:1 ratio
gave the dioranyltellurium dibromides (compounds
5–8) in fair yields (Table 1).
Reduction of compounds 1 and 4 by ethano-
lic solution of hydrazine hydrate gave the corre-
sponding ditellurides (9 and 10) in reasonable yields
(Table 1). Furthermore, the diorganyl tellurides 11,
12, 13, and 14 were prepared by the reduction
of compounds 5, 6, 7, and 8, respectively by hy-
drazine hydrate in boiling ethanol. Attempt to pre-
pare the corresponding tellurenyl bromides (i.e., Ar-
TeBr) from partial reduction of compounds 1 or 4 by
various reducing agents, such as Na2S·9H2O, NaBH4,
and hydrazine hydrate or sodium metabisulfite,
were unsuccessful and yielded the corresponding
Recently, Singh and coworkers [16] reported
the preparation of some tellurated Schiff bases
4-MeOC6H4TeCH2CH2N C(CH3)C6H4-2-OH
and
2-HOC6H4(CH3)C NCH2CH2TeCH2CH2N C(CH3)
C6H4-2-OH from the reaction of {2-[(4-
methoxyphenyl)telluro]ethyl}amine
and
bis(2-
aminoethyl) telluride with o-hydroxyacetophenone,
respectively [16]. Furthermore, the condensation
of bis(o-formylphenyl) diselenide with (R)-(+)-
1-phenylethylamine afforded the chiral azome-
thine
diselenide,
(1-phenylethylimino)methyl)
phenyl)diselanyl)benzylidene-1-phenylethanamine
[17]. On the other hand, a recent study described
the synthesis of monomeric tellurides of type
4-RC6H4(2-(4,4ꢁ-NO2C6H4CH NC6H3-Me)Te
as
the first example of a telluride with 1,4-Te· · ·N
intramolecular interaction [18].
Some years ago, we prepared several organic tel-
lurium compounds containing amino groups by re-
acting aminoarylmercury chlorides with tellurium
tetrabromide in glacial acetic acid [19,20]. Thus, we
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization, and Computational Study of Some New Organotellurium Compounds Containing Azomethine Groups 309
SCHEME 1 Preparative methods for compounds 1–14.
ditellurides. This is probably due to the absence of
the interaction between nitrogen atom of CH N
group and tellurium atom.
in the region 8.42–9.22 ppm (Table 2). In general,
the H NMR spectra of all compounds show all the
1
expected peaks in proper intensity ratio (Table 2).
It is worthy to note that the proton of azomethine
resonate as a singlet between 9.17–9.22 ppm for
compounds 1–8 and 11–14, whereas for the ditel-
lurides 9 and 10 appeared at 8.72 and 8.42 ppm,
respectively. The main reason for this shift toward
a stronger field as compared with compounds 1–8
and 11–14 may be attributed to the coordination
of both azomethine groups through their nitrogen
atoms with both tellurium atoms forming two five-
membered chelate ring structures in solution, as
shown below:
IR spectra for all compounds displayed common
features in certain regions and characteristic bands
in the fingerprint and other regions. The IR spec-
tra confirm the presence of the azomethine group
( CH N ) stretching with a sharp region around
1550 cm−1 (Table 1). Furthermore, a complete con-
densation of primary amino groups is confirmed by
the lack of N H stretching bands in the IR spectra of
all mercurated and tellurated Schiff bases. This con-
1
clusion is also supported by H NMR data, which
show the presence of CH N hydrogen resonances
Heteroatom Chemistry DOI 10.1002/hc

310 Al-Rubaie et al.
TABLE 2 1H and 13C NMR Spectral Data for Selected Compoundsa
Compounds
1H NMR (DMSO-d6); TMS = 0 ppm
13C NMR (DMSO-d6); TMS = 0 ppm
1
7.38 (d, 1H, H-6); 7.45 (dd, 1H, H-5); 7.56 (d, 1H,
H-3); 7.62–7.73 (m, 3H, H-3ꢁ, H-4ꢁ, H-5ꢁ); 7.81–7.91
(m, 2H, H-2ꢁ, H-6ꢁ); 9.19 (s, 1H, CH N ).
122.8 (C-2); 123.3 (C-6): 128.5 (C-3ꢁ, C-5ꢁ); 129.0
(C-2ꢁ, C-6ꢁ); 130.0 (C-3); 130.2 (C-5); 131.0 (C-4ꢁ);
132.1 (C-4); 133.5 (C-1ꢁ); 151.1 (C-1); 160.0
( CH N )
3
3.51 (s, 3H, OCH3); 7.02 (d, 1H, H-6); 7.11–7.20 (m,
2H, H-3, H-5); 7.62–7.74 (m, 2H, H-1, H-3);
7.62–7.74 (m, 3H, H-3ꢁ, H-4ꢁ, H-5ꢁ); 7.82–8.19 (m,
2H, H-2ꢁ, H-6ꢁ); 9.17 (s, 1H, CH N ).
55.4 (OCH3); 116.0 (C-3); 115.2 (C-5); 121.0 (C-2);
123.1 (C-6); 128.2 (C-3ꢁ, C-5ꢁ); 129.0 (C-2ꢁ, C-6ꢁ);
130.8 (C-4ꢁ); 133,6 (C-1ꢁ); 146.2 (C-1); 159.0 (C-4);
160.0 ( CH N ).
5
6
7.35 (d, 2H, H-6), 7.44 (dd, 2H, H-5); 7.58 (d, 2H,
H-3); 7.52–7.61 (m, 6H, H-3ꢁ, H-4ꢁ, H-5ꢁ); 7.79–8.14
(m, 4H, H-3ꢁ, H-6ꢁ); 9.21 (s, 2H, CH N ).
7.39 (dd, 2H, H-5); 7.54 (d, 2H, H-6); 7.62 (d, 2H,
H-3); 7.72–7.78 (m, 6H, H-3ꢁ, H-4ꢁ, H-5ꢁ); 7.82–8.02
(m, 4H, H-2ꢁ, H-6ꢁ); 9.15 (s, 2H, CH N ).
121.2 (C-4); 122.7 (C-2); 124.3 (C-6); 128.7 (C-3ꢁ,
C-5ꢁ); 129.1 (C-2ꢁ, C-6ꢁ); 131.2 (C-4ꢁ); 132.8 (C-3);
133.1 (C-5); 133.8 (C-1ꢁ); 146.2 (C-1); 160.1
( CH N ).
8
7.53 (d, 2H, H-6); 7.38–7.47 (m, 6H, H-3ꢁ, H-4ꢁ, H-5ꢁ);
7.78–8.12 (m, 8H, H-2ꢁ, H-6ꢁ, H-3, H-5); 9.22 (S, 2H,
CH N ).
122.4 (C-5); 122.9 (C-2); 123.2 (C-6); 124.8 (C-3);
128.8 (C-3, C-5ꢁ); 129.1 (C-2ꢁ, C-6ꢁ); 131.2 (C-4ꢁ);
133.6 (C-1ꢁ); 147.2 (C-4); 158.8 (C-1); 160.1
( CH N ).
9
7.35 (d, 2H, H-6); 7.44 (dd, 2H, H-5); 7.56 (d, 2H,
H-3); 7.61–7.72 (m, 6H, H-3ꢁ, H-4ꢁ, H-5ꢁ); 7.79–7.94
(m, 4H, H-2ꢁ, H-6ꢁ); 8.72 (s, 2H, CH N ).
123.0 (C-2); 123.3 (C-6): 128.8 (C-3ꢁ, C-5ꢁ); 129.8
(C-2ꢁ, C-6ꢁ); 130.1 (C-3); 131.0 (C-5); 132.0 (C-4ꢁ);
132.5 (C-4); 133.6 (C-1ꢁ); 150.2 (C-1); 160.2
( CH N )
10
13
14
7.42 (d, 2H, H-6); 7.52–7.60 (m, 6H, H-3, H-4’, H-5’);
7.80–8.15(m, 8H, H-3ꢁ, H-6, H-2ꢁ, H-6ꢁ); 8.42 (s, 2H,
CH N ).
121.8 (C-5); 122.3 (C-2); 123.0 (C-6); 124.6 (C-3);
128.8 (C-3ꢁ, C-5ꢁ); 129.2 (C-2ꢁ, C-6ꢁ); 131.2 (C-4ꢁ);
133.3 (C-1ꢁ); 148.1 (C-4); 157.4 (C-1); 160.1
( CH N ).
3.54 (s, 6H, OCH3); 6.92 (d, 2H, H-6); 7.20–7.28 (m,
4H, H-3, H-5); 7.62–7.74 (m, 6H, H-3ꢁ, H-4ꢁ, H-5ꢁ);
7.92–8.24 (m, 4H, H-2ꢁ, H-6ꢁ); 9.22 (s, 2H,
CH N ).
7.38 (d, 2H, H-6); 7.42–7.55 (m, 6H, H-3ꢁ, H-4ꢁ, H-5ꢁ);
7.82–8.18 (m, 8H, H-3, H-6, H-2ꢁ, H-6ꢁ); 9.20 (s, 2H,
CH N ).
aHydrogen and carbon assignment as illustrated below:
This supports our argument on the inability
to prepare the corresponding tellurenyl halides
from tribromides by partial reduction, though the
theoretical data on the solid compounds disagree
with this (see Computational Studies section).
Carbon-13 NMR spectra gave further support to
the formulation of these new compounds (Table 2).
The spectra revealed the presence of CH N group
around 160 ppm. The large variation for carbon
atoms bearing tellurium may be attributed to the
polarity of Te–C bond [22].
In the mass spectra (EI) of compounds 4, 5,
9, and 10, the molecular ion peaks [M+] were
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization, and Computational Study of Some New Organotellurium Compounds Containing Azomethine Groups 311
observed with low-relative intensity at 592 (5%), 688
(11%), 710 (4.4%), and 718 (3%). Important frag-
ments were also observed, confirming the proposed
structures.
To further confirm our conclusion and to reveal
the true situation in 9 and 10, we carried out cal-
culations with model 3. In this model, the Cl and
NO2 groups connected to the benzene rings in 9 and
10 are omitted, and we suppose that these simplifi-
cations will not induce dramatic change in the ge-
ometric structures and stabilities of the conform-
ers. Table 3 shows F is the most stable conformer,
and there is no exception that in this conformer
Te1· · ·N1 and Te2· · ·N2 secondary interactions are
existed to form two four-membered rings. In con-
former I, there may exist certain interactions of
Te2· · ·N1 and Te1· · ·N2; however, higher energy is
calculated. From the structures of the five conform-
ers, we can understand this matters influence the
stabilities of different conformers. G is the second
stable conformer because in this conformer the two
benzene rings connected to the imine moieties are
both located at the antipositions of the C N double
bond. Thus, the repulsions between the two benzene
rings connected at the two ends of the same imine
moiety are relieved, and such kind of repulsion can
be detected in following conformers H, I, and J. It
is reasonable that there may have repulsion between
the two benzene rings, which are both connected at
the C atoms of the two imine moieties in conformer
G, whereas in conformer F this is not any kind of
repulsion between the benzene rings at all.
COMPUTATIONAL STUDY
To simulate the geometric structures of 9 and 10
and to reveal the Te· · ·N interactions in such a kind
of ditellurides, we employed theoretical calculations
to achieve a better understanding. All the calcula-
tions were performed by using the GAUSSIAN 03
program package [23]. The B3LYP method of DFT
was used to optimize all the structures reported. A
basis set of lanl2dz [24] was chosen for Te atoms
and 6-31G∗ for all other atoms. Frequency calcula-
tions were performed at the same level of theory as
geometry optimizations. All the structures reported
are confirmed to be local minima from frequency
analysis. The optimized structures of different con-
formers of our computational models are given in
Fig. 1, and the distances of Te and N as well as the
energy values of the different conformers of each
model are depicted in Table 3.
The three different conformers of model 1 are
shown in Fig. 1, and in this model all the ben-
zene rings are omitted. Conformer A has the low-
est energy. The Te1· · ·N1 and Te2· · ·N2 distances
˚
are both 3.178 A. Although this distance is longer
From calculations, we know the structures of 9
and 10 must be similar to conformer F in model
3. There are secondary interactions between the Te
atom and N atoms, which are connected at two
neighboring carbons of the same benzene ring, and
four-membered rings are expected to be formed as
a result of secondary interactions, whereas the for-
mation of five-membered rings is not favorable. The
repulsions between the benzene rings in 9 and 10 in-
fluence the stabilities of the conformers mostly, and
the structures in the case of F are ideal.
than the reported Te· · ·N secondary interactions that
˚
are all lower than 3.0 A [25–28], it is still much
˚
shorter than 3.7 A [29], which is the sum of van der
Waals radii of Te and N. The structure of B shows
two five-membered rings can be formed because the
distances of Te2· · ·N1 and Te1· · ·N2 are both only
˚
3.022 A. However, the higher energy of B than A indi-
cates the formations of five-membered rings though
Te· · ·N secondary interactions are not favored. In C,
there has no interaction between the Te atoms and
N atoms at all; thus, there is no surprise and this
conformer has the highest energy. From this com-
putational model, we can conclude that in such kind
of ditellurides the formation of five-membered rings
through Te2· · ·N1 and Te1· · ·N2 interactions is not
favored, and the formation of four-membered rings
through Te1· · ·N1 and Te2· · ·N2 interactions is pre-
ferred. This conclusion is confirmed in the calcula-
tion of model 2. In this model, two benzene rings
connected to the Te atoms are introduced. Although
in conformer E, there may exist interactions between
all the Te atoms and all the N atoms and two five-
membered rings can be formed, the more stable con-
former is D that only has two secondary interactions
of Te1· · ·N1 and Te2· · ·N2.
On the basis of our conclusion on the structures
of 9 and 10, we believe that there have also been such
kinds of secondary Te—N interactions in all other
organotellurium compounds in our experiment. As
shown in Fig. 2, in the optimized skeletal struc-
tures of 1–4, 5–8, and 11–14, the Te—N secondary
interactions are obvious. In compounds 1–4, the sec-
ondary interaction between Te and N is supposed to
be the strongest, since the Te—N distance is only
˚
2.561 A, which is the shortest. In compounds 5–8
and 11–14, the distance between Te and N is longer,
˚
which is all around 3.0 A and still in the range of sec-
ondary interaction. These observations agree well
with the X-ray crystallography study on analogous
compounds [18].
Heteroatom Chemistry DOI 10.1002/hc

312 Al-Rubaie et al.
FIGURE 1 Different conformers of the three computational models. A, B, and C are different conformers of model 1; D and E
are two conformers of model 2; F, G, H, I, and J are different conformers of model 3.
In conclusion, a new series of organotellurium
compounds containing CH N group was pre-
pared. It was disappointing that on reduction
compounds 1 and 4 by various reducing agents
gave ultimately the corresponding ditellurides in-
stead of organotellurium(II) halides (RTeX). Evi-
dence is available to suggest that some of these
organotellurium compounds (i.e., telluride and ditel-
lurides) form complexes with a range of metal salts.
EXPERIMENTAL
Physical Measurements
1H and 13C NMR spectra were obtained with Bruker
LA-250 (250 MHz) and Bruker 300 spectrome-
ter instruments. They were recorded in DMSO-
d6 solutions containing TMS as internal standard.
Elemental analyses (C, H, and N) were performed
by Analytical Laboratories of Konstanz University,
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization, and Computational Study of Some New Organotellurium Compounds Containing Azomethine Groups 313
TABLE 3 The Te· · ·N Interactions, Total Energies (in Hartree) and Sum of the Electronic and Zero-Point Energies (in Hartree)
of Different Conformers of the Three Computational Models
Te2· · ·N1
3.022
Te1· · ·N1
Te1· · ·N2
Te2· · ·N2
EHF
EHF (0 K)
ꢀEHF
ꢀEHF (0 K)
1
A
B
C
D
E
F
G
H
I
3.178
3.521
3.178
3.521
−358.959209
−358.954853
−358.952871
−666.258749
−666.251605
−1128.385494
−1128.376383
−1128.367427
−1128.358196
−1128.357960
−358.831186
−358.826404
−358.824927
−666.035436
−666.028030
−1127.998883
−1127.989693
−1127.980484
−1127.971187
−1127.971006
0.0
2.7
4.0
0.0
4.5
0.0
5.7
11.3
16.9
17.3
0.0
3.0
3.9
0.0
4.6
0.0
5.8
11.5
17.4
17.5
3.022
2
3
2.991
3.288
2.997
3.277
3.284
3.284
3.325
2.991
3.287
3.233
3.288
2.996
3.562
3.462
3.367
4.324
3.602
3.536
3.331
5.030
3.277
3.290
3.292
3.325
J
˚
Distances are in A and relative energies are in kcal/mol.
Germany. Mass spectra were determined on a Finni-
gan MAT-321 spectrometer at 70 eV, and measure-
ments were carried out on 130Te isotope.
Synthesis of 2-(Benzylideneamino)-5-
chlorophenyltellurium Tribromide (1)
A mixture of 2-(benzylideneamino)-5-chlorophenyl
mercuric chloride (0.81 g; 1.79 mmol) and tellurium
tetrabromide (0.80 g; 1.79 mmol) in dry chloroform
(30 cm3) was stirred and refluxed for 4 h under nitro-
gen atmosphere. The resulting solution was filtered
hot and cooled to room temperature. The resulting
precipitate was collected by filtration. Recrystal-
lization of the solid product from ether/hexane
(7/3) gave compound 1 as yellow solid in 83% yield
(1.96 g), mp 144–146◦C. 2-(Benzylideneamino)-5-
bromophenyltellurium tribromide (2), 2-(benzyl-
Synthesis
All reactions were carried out under dry ni-
trogen atmosphere. All solvents were dried and
freshly distilled under nitrogen before use. 4-Chloro-
2-aminophenyl-tellurium(IV)tribromide, 4-bromo-
2-aminophenyl tellurium(IV) tribromide [19,20],
4-methoxy-2-aminophenyltellurium(IV) tribromide
[19,20], and 4-nitro-2-aminophenyltellurium(IV)
tribromide [19,20], and tellurium tetrabromide
[21] were prepared by following the literature
methods.
ideneamino)-5-methoxyphenyltellurium
tribro-
mide (3), and 2-(benzylideneamino)-5-nitrophenyl-
tellurium tribromide (5) were prepared by following
the above method.
Synthesis of 2-(Benzylideneamino)-5-
chlorophenyl Mercuric Chloride
Bis(2-(benzylideneamino)-5-chlorophenyl)-
tellurium Dibromide (5)
A solution of 2-amino-5-chlorophenyl mercuric chlo-
ride (1.08 g; 3 mmol) and benzaldehyde (0.32 g;
3 mmol) in ethanol (60 cm3) containing three drops
of sulfuric acid was refluxed for 1 h. After cooling,
the precipitate was collected by filtration. The solid
compound was washed several times with ethanol
and dried in vacuo.
A mixture of 2-(benzylideneamino)-5-chlorophenyl
mercuric chloride (1.62 g; 3.58 mmol) and tel-
lurium tetrabromide (0.80 g; 1.79 mmol) in dry
chloroform (40 cm3) was stirred and refluxed for
5 h under nitrogen atmosphere. The resulting so-
lution was filtered hot and cooled to room tem-
perature. The resulting precipitate was collected by
filtration. Recrystallization of the brown solid prod-
uct from ethanol/chloroform (4/1) gave compound
5 as yellowish-brown solid in 52% yield (mp 137–
139◦C).
Compounds
2-(benzylideneamino)-5-bromo-
phenyl mercuric chloride, 2-(benzylideneamino)-5-
methoxyphenyl mercuric chloride, and 2-(benzyl-
ideneamino)-5-nitrophenyl mercuric chloride were
prepared by following the above general synthetic
procedure using appropriate reactants. All mecu-
rated Schiff bases gave satisfactory analyses and are
not reported.
Bis(2-(benzylideneamino)-5-bromophenyl)tellu-
rium dibromide (6), 2-(benzylideneamino)-5-metho-
xyphenyl)tellurium dibromide (7), and bis(2-
Heteroatom Chemistry DOI 10.1002/hc

314 Al-Rubaie et al.
˚
FIGURE 2 Optimized skeleton structures for compounds 1–4 (a), 5–8 (b), and 11–14 (c). Distances are in A.
(benzylideneamino)-5-nitrophenyl)tellurium dibro-
mide (8) were prepared by reacting 2 mol of the
corresponding mercurated Schiff base with 1 mol of
tellurium tetrabromide in dry chloroform under the
same conditions for the preparation of compound 5.
An ethanolic solution of hydrazine hydrate (0.26 g;
8 mmol) was added dropwise to the refluxing so-
lution until the evolution of nitrogen ceased. The
resulting solution was cooled to room temperature,
poured into 1 dm3 of water, and extracted with ether
(3 × 100 cm3). The ether extracts were dried over an-
hydrous calcium chloride, and evaporation of the
solvent afforded an orange precipitate. Recrystalliza-
tion from ethanol gave an orange solid in 64% (mp
122–124◦C). Compound bis(2-(benzylideneamino)-
5-nitrophenyl)ditelluride (10) was prepared by
Synthesis of Bis(2-(benzylideneamino)-5-
chlorophenyl)ditelluride (9)
Compound 1 (1.16 g; 2 mmol) was dissolved in
25 cm3 of hot ethanol and heated under reflux.
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization, and Computational Study of Some New Organotellurium Compounds Containing Azomethine Groups 315
[6] Maksimenko, A. A.; Sadekov, I. D.; Maslakov, A. G.;
Mehrotra, G. K.; Borodkin, G. S.; Kompan,O. E.;
Struchkov, Yu. I.; Fedotov, M. A.; Minkin,V. I. Metal-
lorg Khim 1989, 2, 298.
following the above method for the preparation of
compound 9.
[7] Sadekov, I. D.; Maksimenko, A. A.; Mehrotra, G. K;
Minkin, V. I. Zh Org Khim 1987, 23, 657.
[8] Sadekov, I. D; Minkin, V. I. ARKiVOC 2001, 125, and
references therein.
[9] Sadekov, I. D.; Nivorozhkin, V. L.; Zakharov, A. V.;
Minkin, V. I. Zh Org Khim 1996, 32, 1434.
[10] Minkin, V. I.; Sadekov, I. D.; Zakharov, A. V.;
Nivorozhkin, V. L.; Kompan, O.E.; Struchkov, Yu.
T. J Organomet Chem 1997, 233, 536.
[11] Nivorozhkin, V. L.; Zakharov, A. V.; Sadekov, I. D.;
Minkin, V. I. Zh Org Khim 2000, 36, 631.
Synthesis of Bis(2-(benzylideneamino)-5-
chlorophenyl)telluride (11)
Bis(2-(benzylideneamino)-5-chlorophenyl)tellurium
dibromide (5) (0.72 g; 1 mmol) was dissolved in
25 cm3 of hot ethanol. Hydrazine hydrate in hot
ethanol was added dropwise until evolution of nitro-
gen ceased. The resulting solution was poured into
500 cm3 of water, and a pale yellow precipitate was
formed. The product was recrystallized from chloro-
form to give yellow precipitate in 64% yield (0.42 g,
mp 134–136◦C).
[12] Abed, Y.; Al-Salim, N. I.; Greaves, M. R.; McWhinnie,
W. R.; West, A. A.; Hamor, T. A. J Chem Soc, Dalton
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[13] Al-Salim, N. I; McWhinnie, W. R.; Hamor, T. A. J
Chem Soc, Chem Commun 1989, 453.
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Organomet Chem 1988, 356, 159.
[15] Sadekov, I. D.; Maksimenko, A. A.; Kompan, O. E.;
Maslakov, A. G.; Struchkov, Yu. I.; Minkin, V. I. Met-
allorg Khim 1989, 2, 1260.
[16] Kumar, R. P.; Singh, A. K.; Butcher, R. J.; Sharma,
P.; Toscano, R. A. Eur J Inorg Chem 2004, 1107.
[17] Panda, S.; Zade, S. S.; Singh, H. B.; Wolmersha¨user,
G. J Organomet Chem 2005, 690, 4142.
[18] Ashk, K. S.; Anamika; Kumar, A.; Singh, P.;
Srivastava, R. C.; Bucher, R. J.; Beckmann, J.;
Duthine, A. J Organomet Chem 2006, 691, 1954.
[19] Al-Rubaie, A. Z.; Al-Salim, N. I.; Al-Jadaan, S. A. N. J
Organomet Chem 1993, 443, 67.
[20] Al-Rubaie, A. Z.; Al-Jadaan, S. A. N. Appl Organomet
Chem 1998, 12, 79.
[21] Cocksedge, H. E. J Chem Soc 1908, 2175.
[22] Al-Rubaie, A, Z.; Al-Derawi, A. K. Heteroatom Chem
2007, 18, 93 and references therein.
[23] Frisch, M. J., et. al. Gaussian, Inc., GAUSSIAN03,
Revision C.02, Wallingford CT, 2004.
Compounds
bis(2-(benzylideneamino)-5-bro-
mophenyl)telluride (12), bis(2-(benzylideneamino)-
5-methoxyphenyl)telluride (13), and bis(2-(benzyli-
deneamino)-5-nitrophenyl)telluride (14) were pre-
pared by the reduction of compounds 6–8 by
hydrazine hydrate in boiling ethanol and as for
compound 11.
ACKNOWLEDGMENTS
Authors thank Prof. N. A. Al-Masoudi (Konstanz
University, Germany) for providing some of CHN
analyses, NMR, and mass spectroscopic data. We
are also thankful to Department of Chemistry,
College of Arts and Science, Tarhona, Almer-
gab University, Libya for providing facilities and
Petroleum Research Center, Tripoli, Libya for pro-
viding some of the IR and NMR spectroscopic data.
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(b) Wadt, W. R.; Hay, P. J. J Chem Phys 1985, 82, 284;
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[25] Majeed, Z.; McWhinnie, W. R.; Hamor, T. A. J
Organomet Chem 1997, 549, 257.
[26] Cozzolino, A. F.; Britten, J. F.; Vargas-Baca, I. Cryst
Growth Des 2006, 6, 181.
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Heteroatom Chemistry DOI 10.1002/hc