Telluroxane-supported coordination ligands: Synthetic and structural aspects

Article abstract of DOI:10.1016/j.poly.2012.06.005

The reactions of (4-MeOC₆H₄)₂TeO with selected carboxylic acids and phenols afforded the formation of mononuclear organotelluroxanes. The utilization of functional carboxylic acids/phenols, such as 2,2-bis(3,5-dimethylpyra

Full text of DOI:10.1016/j.poly.2012.06.005

Polyhedron 52 (2013) 1362–1368
Contents lists available at SciVerse ScienceDirect
Polyhedron
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Telluroxane-supported coordination ligands: Synthetic and structural aspects
Vadapalli Chandrasekhar a, , Arun Kumar a,b, Mrituanjay D. Pandey a, Ramesh K. Metre a
⇑
a Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India
b School of Chemical Sciences, National Institute of Science Education and Research, Institute of Physics Campus, Bhubaneswar 751 005, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Available online 15 June 2012
The reactions of (4-MeOC6H4)2TeO with selected carboxylic acids and phenols afforded the formation of
mononuclear organotelluroxanes. The utilization of functional carboxylic acids/phenols, such as 2,2-
bis(3,5-dimethylpyrazol-1-yl)acetic acid, 2,2-bis(benzotriazole-1-yl)acetic acid, and Schiff base-contain-
ing benzoic acids and phenols allowed the preparation of organotelluroxanes containing a multi-site
coordinating capability. X-ray crystal structure studies on these compounds reveal interesting supramo-
lecular architectures in their solid-state including the presence of the four-membered Te2O2 structural
unit in some instances.
Dedicated to the memory of A. Werner,
father of coordination chemistry
Keywords:
Organotelluroxanes
Multi-site-coordination ligands
Crystal structure
Ó 2012 Elsevier Ltd. All rights reserved.
Organotellurium carboxylates
Organotellurium bis(phenolates)
1. Introduction
Synthesis and structural characterization of the products obtained
in these various reactions is discussed herein.
Recently we have been interested in using inorganic rings and
cages as platforms for building multi-site coordination ligands,
compounds with an electrochemically or photochemically active
periphery, or compounds that possess catalytically active sites
[1–6]. We were interested in extending this methodology to
organotelluroxane chemistry. Telluroxanes have been studied in
recent years for several reasons [7–19]. One important reason is
the possibility of achieving structural and compositional diversity
among these compounds [7,11]. In this context, we have reported
organotelluroxanes, that contain diverse structural motifs such as
2. Results and discussion
2.1. Synthesis
The reactions of (4-MeOC6H4)2TeO with various carboxylic
acids and phenols afforded molecular compounds 1–14 as shown
in Scheme 1. Representative 125Te NMR for compounds 1, 2, 3, 11
and 14 showed singlets at 1033, 1122, 1102, 1079 and 992 ppm,
respectively. These chemical shifts are comparable to some of the
telluoroxanes [7] and diorganotellurium bis(phenolates) reported
in literature [11]. ESI-HRMS spectra for 1–14 show prominent
parent ion peaks revealing the stability of these compounds in
solution (see experimental). Other spectroscopic data (see experi-
mental section) (IR, 1H and 13C) are consistent with their molecular
formulation. The molecular structures of 1, 5, 8–12 have been
determined by X-ray crystallography.
([OTeOH], [TeO2], [(O–Te)2(l-O)] and [OTe(l-O)Te(l-O)TeO] in
the reactions of (4-MeOC6H4)2TeO with 2-, 3- and 4-pyridine car-
boxylic acids [7].
In this study we demonstrate a general synthetic methodology
to prepare organotelluroxanes that contain multi-site coordination
ligands. This was achieved by the reaction of (4-MeOC6H4)2TeO
with various carboxylic acids or phenols that contain coordinating
groups such as 2,2-bis(3,5-dimethylpyrazol-1-yl)acetic acid, LH1,
2,2-bis(benzotriazole-1-yl)acetic acid, LH2, and Schiff base-con-
taining benzoic acids and -phenols (LH3, LH4, LH13 and LH14)
(Scheme 1).
2.2. X-ray crystallographic studies for 1, 5, 8–12
The crystal data for 1, 5, 8–12 are summarized in Table 1. Com-
pounds 1, 5, 8–11 are diorganotellurium dicarboxylates. The gross
structural features of these compounds are similar. In view of this,
in the following, the molecular structure of 1 is described. Com-
pounds 5, 9, 10, while possessing similar structural features as 1,
have an additional telluroxane dimeric motif in their crystal struc-
tures. Accordingly, this is dealt separately. Compound 8 possesses a
dimeric motif resulting from intermolecular Te–O interactions
In addition, the reactions of (4-MeOC6H4)2TeO with nitro- and
amino-substituted benzoic acids (LH5-LH10, cyclohexylcarboxylic
acid (LH11) and 4-nitrophenol (LH12) have also been carried out.
⇑
Corresponding author. Tel.: +91 512 259 7259; fax: +91 512 259 7436.
E-mail address: vc@iitk.ac.in (V. Chandrasekhar).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.06.005

V. Chandrasekhar et al. / Polyhedron 52 (2013) 1362–1368
1363
Scheme 1. Reactions of (4-MeOC6H4)2TeO with carboxylic acids and phenols.
between tellurium and the nitro substituent of the carboxylate
ligand. This interaction is in fact similar to that found in the diorg-
anotellurium (bisphenolate), 12, which is described separately.
Compound 11, on the other hand has a similar molecular structure
as that of 1, 5, 8–10 (Supplementary Information); however, it does
not possesses a supramolecular structure as found in 1, 5, 8–10.
constituted by Te–O1–C1–O2 and Te–O3–C2–O4 is 75.81(2)°. A
general comparison of the Te ꢀ ꢀ ꢀ O intramolecular distances and
the dihedral angles observed in telluroxanes is summarized in
Table 2.
The crystal structure of 1 reveals the formation of a 1D- zig-zag
sheet where the molecules are held together through weak
C ꢁ H ꢀ ꢀ ꢀ O and
pꢀ ꢀ ꢀ p (3.7688(3) Å) interactions (Supplementary
Information). In these zig-zag sheets, alternate molecules are
parallel to each other. For illustration, a portion of such a sheet is
2.2.1. Molecular and crystal structure of 1
The ORTEP diagram of 1 is shown in Fig. 1. Important bond dis-
tance and angle data for this compound are summarized in the
caption of Fig. 1. This reveals that the telluroxane moiety supports
two potential coordinating motifs, which can be used for interac-
tion with transition metal ions. The immediate coordination envi-
ronment around tellurium contains two carbon and two oxygen
atoms. The coordination geometry around tellurium, because of
the presence of the lone pair of electrons and weaker Te ꢀ ꢀ ꢀ O inter-
actions, is not regular. In the approximate see-saw geometry
around tellurium, the apical positions are occupied by the more
electronegative oxygen atoms whereas the carbon atoms are pres-
ent in the equatorial positions. The presence of the lone pair at the
third equatorial position is inferred by the reduction of the equato-
rial C–Te–C and trans-axial O–Te–O bond angles which are
102.45(2)° and 164.68(1)°, respectively. The observed Te–O
(2.125(3), 2.137(3) Å) and Te–C (2.082(4), 2.109(4) Å) bond lengths
are in good agreement with analogous telluroxanes [11]. In addi-
tion, the carboxylate oxygen atoms are involved in weak Te–O
interactions (3.055(3) Å) and (3.059(3) Å); these distances are
much smaller than the sum of the van der Waals’ radii of Te and
O (3.60 Å) and greater than the sum of their covalent radii
(2.03 Å) [20]. The dihedral angle between the two mean planes
shown in Fig. 2. The two benzene rings involved in the
action are not perfectly planar but are offset with respect to each
other with a dihedral angle of 17.8 (1)°. Such stacking interac-
tions between -donor and -accepting ring systems have been
discussed in the literature [21].
pꢀ ꢀ ꢀ p inter-
p–p
p
p
2.2.2. Dimeric Te2O2 motifs in 5, 9–10
The detailed structural description of 5, 9–10 is not attempted
in view of their structural similarity with 1. In this section we
would only comment on the intra- and intermolecular Te–O inter-
actions present in these compounds (Supplementary Information).
In contrast to 1 and 11, compounds 5, 9 and 10 possess, un-
iquely a dimeric Te2O2 motif, resulting due to intermolecular
Te ꢀ ꢀ ꢀ O interactions (Table 2). The presence of such dimeric motifs
in organotelluroxane carboxylate structures has been discussed by
us in a previous report [7]. Two different types of dimeric Te2O2
motifs are found in 5, 9 and 10. The dimeric motifs found in 5
and 10 are similar, where both the carboxylate groups on each
Te are involved in intermolecular Te ꢀ ꢀ ꢀ O interactions (Supplemen-
tary Information). However, in 9, only one carboxylate group on
each Te is involved in intermolecular Te ꢀ ꢀ ꢀ O interactions. Interest-

1364
V. Chandrasekhar et al. / Polyhedron 52 (2013) 1362–1368
Table 1
X-ray crystallographic data for compounds 1, 5, 8, 9, 10, 11 and 12.
1
5
8
9
10
11
12
Empirical
formula
Formula weight
T (K)
C
39H46Cl2N8O6Te
C28H26N2O6Te
C35H30N2O10Te
C35H30N2O10Te
C28H20N4O14Te
C28H36O6Te
C26H22N2O8Te
921.34
100(2)
0.71073
monoclinic
P21/n
10.6475(10)
16.1172(14)
23.994(2)
90
94.155(2)
90
4106.8(6)
4
614.11
273(2)
0.71073
triclinic
766.21
100(2)
0.71073
monoclinic
P21/n
13.245(2)
14.468(3)
16.983(3)
90
766.21
100(2)
0.71073
triclinic
764.08
273(2)
0.71073
triclinic
P1
13.686(5)
13.692(5)
13.795(5)
60.264(5)
60.300(5)
89.991(5)
1843.5(12)
2
596.17
273(2)
0.71073
monoclinic
C2/c
26.612 (7)
15.094 (6)
17.275 (4)
90
127.08(2)
90
5536.2(5)
8
618.06
100(2)
0.71073
triclinic
k (Å)
Crystal system
Space group
a (Å)
b (Å)
c (Å]
ꢀ
ꢀ
ꢀ
P1
P1
P1
11.766(5)
11.791(5)
20.248(5)
103.764(5)
103.547(5)
94.373(5)
2626.5(17)
4
9.8985(10)
12.9241(14)
12.9369(13)
85.372(2)
88.715(2)
84.774(2)
1642.6(3)
2
10.0747(6)
10.4547(6)
12.6379(7)
104.5510(10)
97.5700(10)
100.6360(10)
1243.90(12)
2
a
(°)
b (°)
90
c
(°)
97.758(4)
3224.7(10)
4
1.578
0.986
V (Å3)
Z
Dcalcd. (g cmꢁ3
)
1.490
0.910
1.553
1.178
1.549
0.967
1.376
0.871
1.431
1.113
1.650
1.250
l
(mmꢁ1
)
F(000)
1880
1232
1544
772
760
2432
616
Crystal size (mm) 0.09 ꢂ 0.08 ꢂ 0.04 0.12 ꢂ 0.05 ꢂ 0.03 0.07 ꢂ 0.05 ꢂ 0.03 0.09 ꢂ 0.07 ꢂ 0.05 0.09 ꢂ 0.06 ꢂ 0.04 0.12 ꢂ 0.08 ꢂ 0.04 0.11 ꢂ 0.07 ꢂ 0.04
h (°)
Limiting indices
2.12 to 28.35
ꢁ14 6 h 6 9
ꢁ21 6 k 6 21
ꢁ30 6 l 6 31
26333
2.15 to 27.00
ꢁ11 6 h 6 15
ꢁ14 6 k 6 15
ꢁ25 6 l 6 25
16000
2.09 to 28.33
ꢁ17 6 h 6 11
ꢁ19 6 k 6 19
ꢁ17 6 l 6 22
20821
2.07 to 26.50
ꢁ12 6 h 6 11
ꢁ12 6 k 6 16
ꢁ16 6 l 6 12
9528
2.07 to 24.97
ꢁ16 6 h 6 11
ꢁ16 6 k 6 14
ꢁ16 6 l 6 10
9533
2.36 to 28.40
ꢁ32 6 h 6 35
ꢁ18 6 k 6 20
ꢁ22 6 l 6 22
17637
2.27 to 28.3
ꢁ11 6 h 6 13
ꢁ13 6 k 6 10
ꢁ16 6 l 6 16
8198
Reflections
collected
Independent
reflections
10093 (0.0446)
11158 (0.0224)
7928 (0.0943)
6606 (0.0330)
7710 (0.0203)
6805 (0.0511)
5866 (0.0187)
(Rint
)
Refinement
method
Full-matrix least-
squares on F2
10093/0/505
Full-matrix least-
squares on F2
11158/0/667
Full-matrix least-
squares on F2
7928/0/436
Full-matrix least-
squares on F2
6606/0/421
Full-matrix least-
squares on F2
7710/5/843
Full-matrix least-
squares on F2
6805/14/318
Full-matrix least-
squares on F2
5866/0/336
Data/restraints/
parameters
Goodness-of-fit
(GOF) on F2
Final R indices
[I>2sigma(I)]
R indices (all
data)
1.158
1.136
1.046
1.096
1.003
1.055
1.246
R1 = 0.0514,
wR2 = 0.1333
R1 = 0.0500,
wR2 = 0.1316
R1 = 0.0717,
wR2 = 0.1745
R1 = 0.0572,
wR2 = 0.1021
R1 = 0.1340,
wR2 = 0.1438
R1 = 0.0495,
wR2 = 0.1214
R1 = 0.0645,
wR2 = 0.1509
R1 = 0.0423,
wR2 = 0.1113
R1 = 0.0467,
wR2 = 0.1153
R1 = 0.0856,
wR2 = 0.2439
R1 = 0.1661,
wR2 = 0.3011
R1 = 0.0445,
wR2 = 0.0976
R1 = 0.0660,
wR2 = 0.1559
R1 = 0.0713,
wR2 = 0.1897
ingly, the dimeric motif found in 9 (Fig. 3) is also similar to the
intramolecular dimeric Bi2O2 motif generally found in bismuth car-
boxylates [22].
2.2.3. Molecular structure of 12
The ORTEP diagram of 12 is given in Fig. 4. The bond parameters
of 12 are summarized in the caption of Fig. 4. In 12, the axial
Te–O bond lengths [Te–O1, 2.090(4) Å and Te–O2, 2.130(4) Å] are
comparable to those reported for Ph2Te(OPh)2, (2.074(2) Å) and
(p-Me2NC6H4)2Te(OPh)2, (2.111(2) Å) [11]. The nitro substituent
on the benzene ring in 12, is engaged in an intermolecular second-
ary Te–O interaction, forming a centrosymmetric dimeric motif
leading to a hexacordinate tellurium center (Fig. 5). A similar type
of interaction is also found in the organotellurium dicarboxylate 8
(Supplementary information). Similar to other compounds de-
scribed in this study, 12 also possesses an extensive supramolecular
structure as a result of several weak secondary interactions
(Supplementary information).
3. Conclusions
In summary, we report the reactions of (4-MeOC6H4)2TeO with
selected carboxylic acids and phenols which affford mononuclear
compounds (4-MeOC6H4)2TeO (O2CR)2 and (4-MeOC6H4)2Te(OR0)2,
respectively. The utilization of functional carboxylic acids/phenols
allows the preparation of organotelluroxanes containing a multi-
site coordinating capability. The coordination chemistry of such
ligands is expected to be rich and interesting. Currently, we are
investigating this possibility.
Fig. 1. Structure of 1. Ellipsoids are drawn at the 60% probability level. Selected bond
distances (Å) and angles (°): Te–C3, 2.109(4); Te–C10, 2.082(4); Te–O1, 2.137(3); Te–
O3, 2.125(3); Te ꢀ ꢀ ꢀ O2, 3.060(3); Te ꢀ ꢀ ꢀ O4, 3.055 (3); C3–Te–C10, 102.45(17); O1–
Te–O3, 164.68(12); O3–Te–C3, 87.54(14); O3–Te–C10, 83.54(14); O1–Te–C3,
81.74(14); O1–Te–C10, 88.10(14); O1 ꢁ Te ꢀ ꢀ ꢀ O2, 46.91(9); O3 ꢁ Te ꢀ ꢀ ꢀ O4, 47.09
(1); C2 ꢁ O4 ꢀ ꢀ ꢀ Te, 72.01 (2); C1 ꢁ O2 ꢀ ꢀ ꢀ Te, 72.16 (2); O2 ꢀ ꢀ ꢀ Te ꢀ ꢀ ꢀ O4, 122.67 (8).

V. Chandrasekhar et al. / Polyhedron 52 (2013) 1362–1368
1365
Table 2
Te–O intramolecular distances and the dihedral angles between 1,4-rings in
monotelluroxanes.
Compounds
Te ꢀ ꢀ ꢀ O1
Te ꢀ ꢀ ꢀ O3
Dihedral
(°)
Intermolecular
distances
(Å)
(Å)
1
3.059(3)
3.021(8)
3.022(5)
3.006(1)
3.031(5)
3.025(4)
75.83(14)
73.31(17)
34.43(14)
5a
Te1A ꢀ ꢀ ꢀ O2B, 3.217(6)
Te1A ꢀ ꢀ ꢀ O4B, 3.210(6)
Te1B ꢀ ꢀ ꢀ O2A, 3.549(9)
Te1B0 ꢀ ꢀ ꢀ O4A,
3.536(8)
Te1A–Te1B, 3.843(3)
Te ꢀ ꢀ ꢀ O8, 3.331(9)
Te ꢀ ꢀ ꢀ O2, 3.309(7)
Te1A ꢀ ꢀ ꢀ O2B, 3.428(1)
Te1A ꢀ ꢀ ꢀ O4B, 3.454(5)
Te1B ꢀ ꢀ ꢀ O2A,
8
2.984(3)
2.969(9)
2.969(8)
2.978(10)
2.902(24)
2.937(18)
2.984(56)
2.979(83)
74.73(82)
13.99(56)
59.22(64)
59.29(23)
9
10a
3.441(12)
Te1B0 ꢀ ꢀ ꢀ O4A,
3.437(6)
11
12
2.996(17)
2.954(71)
33.75(67)
Te ꢀ ꢀ ꢀ O7, 3.527(1)
Te ꢀ ꢀ ꢀ O8, 3.130(6)
Fig. 3. Te2O2 structural motifs in dimeric units are formed through inter- and intra-
molecular Te ꢀ ꢀ ꢀ O interactions in 9. Atoms involved in each Te2O2 interactions are
lying in a plane. Te ꢀ ꢀ ꢀ O2, 2.969(4); Te ꢀ ꢀ ꢀ O20, 3.309(3).Viewing direction: x, 15.2661;
y, 53.0491; z, 108.587. The bond parameters for theTe2O2 motif are as follows:
Te ꢀ ꢀ ꢀ O2, 2.969(4) Å; Te ꢀ ꢀ ꢀ O20, 3.309(4) Å; O2 ꢀ ꢀ ꢀ Te ꢀ ꢀ ꢀ O20, 84.02(13)°;
Te ꢀ ꢀ ꢀ O2 ꢀ ꢀ ꢀ Te0, 95.96(11)°.
Ar2Te(L1)2
[7]
Ar2Te(L2)2
[7]
2.978(2)
3.028(5)
2.943(16)
2.952(11)
13.82(64)
11.36(77)
L1: orthopyridine carboxylate.
L2: metapyridine carboxylate.
a
Two values for independent molecules‘a’ and ‘b’.
and are uncorrected. Elemental Analyses of the compounds were
obtained using a Thermoquest CE instrument CHNS-O, EA/1110
model. IR spectra were recorded as KBr pellets with a Bruker Vec-
4. Experimental section
tor 22 FTIR spectrophotometer operating from 4000–400 cmꢁ1
.
Electrospray ionization mass spectra were recorded with
a
4.1. Reagents and general procedures
WATERS–HAB213 spectrometer by using capillary 2.7 kV. NMR
(1H, 13C and 125Te NMR) spectra were recorded with a JEOL JNM
LAMBDA 400 model spectrometer or a JEOL JNM DELTA 500 model
spectrometer.
All the reactions were carried out using anhydrous solvents
unless otherwise stated. The solvents were purified by standard
procedures and stored under N2 atmosphere and over activated
molecular sieves [23]. TeCl4, 3,5-dimethylpyrazole, pyrene-1-car-
boxaldehyde, dibromo- and, dichloroacetic acids, benzyltriethyl-
ammonium chloride, benzotriazole, cyclohexanecarboxylic acid
were purchased from Aldrich Chemical Co. (USA) and were used
as received. Anisole, 3-nitro-, 4-nitro- and 3,5-dinitro- benzoic
acids, 2-amino-, 4-amino- and 3,5-diamino- benzoic acids, 4-nitro-
phenol, 2-aminophenol, 2-hydroxybenzaldehyde,benzaldehyde
and p-toluidine were procured from s.d. Fine. Chem. Ltd., Mumbai,
India and used as such. Anisole was distilled under N2 atmosphere
before use. Sodium hydroxide was purchased from RFCL Limited,
New Delhi, India and was used as such. (4-MeOC6H4)2TeO was pre-
pared from the reaction of anisole with TeCl4 followed by its base
hydrolysis with NaOH as reported in the literature [24]. Melting
points were measured by using a JSGW melting point apparatus
4.2. Reactions of bis(4-methoxyphenyl)telluroxide with LH1–LH14
4.2.1. General procedure
A suspension of bis(4-methoxyphenyl)telluroxide (2 mmol) and
ligand, LH (4 mmol) in 20 mL solvent was stirred under reflux con-
dition with Dean-Stark azeotropic removal of water (the reaction
medium, duration of reflux and crystallizing solvents are men-
tioned along with the characterization data of compounds). The
resultant reaction mixture was filtered through short silica col-
umn, evaporated to dryness and recrystallized. At this stage sticky
solid was obtained in the reactions of phenols which was dissolved
in dry methanol-chloroform mixture and passed through silica col-
umn. The volatiles were removed under vacuum and recrystallized.
Fig. 2. View of 1-D supramolecular chain of 1. The molecules are held together in zig-zag manner through weak C7 ꢁ H7 ꢀ ꢀ ꢀ O2, 2.630(3), C9 ꢁ H9C ꢀ ꢀ ꢀ O2, 2.580(3) and
pꢀ ꢀ ꢀ p
[Ct ꢀ ꢀ ꢀ Ct, 3.769(3) Å] interactions. Lattice solvent, CH2Cl2 are held by C39 ꢁ H39A ꢀ ꢀ ꢀ O2 (2.673(3) Å and C39 ꢁ H39A ꢀ ꢀ ꢀ N2 (2.614(3) Å) interactions. Viewing direction = x,
ꢁ176.744; y, 59.9502; z, ꢁ93.0154.

1366
V. Chandrasekhar et al. / Polyhedron 52 (2013) 1362–1368
839.2521 (found), 839.2524 (calculated) for [M+H]+; 1040.3787
(found), 1040.3790 (calculated) for [M+C6H6+3MeCN+H]+. Anal.
Calc. for C38H44N8O6Te (836.41): C, 54.57; H, 5.30; N, 13.40. Found:
C, 54.67; H, 5.22; N, 13.66%.
2: Reaction medium: 1% methanol-toluene; reflux time: 8 h;
crystallizing solvent: benzene. Amounts of starting materials: (4-
MeOC6H4)2TeO, 0.715 (2 mmol) and 2,2-bis(benzotriazol-1-yl)ace-
tic acid, 1.15 g (4 mmol). Yield: 1.02 g (55%). m.p. 172–176 °C. IR
(KBr)/cmꢁ1 masym (C=O): 1719.3. 1H NMR (500 MHz, CDCl3): d
:
3.64 (s, 6H, OMe), 6.39 (s, 2H, CH), 6.91–8.33 (m, 24H, arom) ppm.
13C NMR (500 MHz, CDCl3): d 173.7 (C=O), 160.3 (p-anisyl-C), 147.0
& 136.5 (ring-C attached to triazol-N), 54.8 (OMe) ppm. 125Te NMR
(157.8 MHz, CDCl3): d = 1122 (s) ppm. ESI-MS: m/z = 1009.2176
(found), 1009.2178 (calculated) for [M+C6H6+H]+. Anal. Calc. for-
C42H32N12O6Te (928.38): C, 54.34; H, 3.47; N, 18.10. Found: C,
54.21; H, 3.49; N, 18.32%.
3: Reaction medium: 5% methanol–toluene; reflux time: 12 h;
crystallizing solvent: methanol–toluene (1:1). Amounts of starting
materials: (4-MeOC6H4)2TeO, 0.714 (2 mmol) and 2-(pyren-1-
ylmethyleneamino)benzoic acid, 1.39 g (4 mmol). Yield: 1.31 g
(61%). m.p. 182–185 °C. IR (KBr)/cmꢁ1
: masym (C=O): 1694.4, masym
(CH=N): 1596.3. 1H NMR (500 MHz, CDCl3): d 3.87 (s, 6H, OMe),
6.54–8.31 (m, 34H, arom), 9.25 (s, 2H, CH=N) ppm. 13C NMR
(500 MHz, CDCl3): d 170.6 (OCO), 159.3 (p-anisyl-C), 156.8 (CH=N),
154.7 (ring
C
attached to N), 55.4 (OMe) ppm. 125Te NMR
Fig. 4. Structure of 12. ORTEP diagram, ellipsoids are drawn at the 60% probability
level. Selected bond distances (Å) and angles (°) are as follows: Te–C3, 2.099(6); Te–
C10, 2.084(5); Te–O1, 2.090(4); Te–O2, 2.130(4); C3–Te–C10, 100.31(2); O1–Te–O2,
167.73 (17); O2–Te–C3, 83.02(21); O2–Te–C10, 88.33(21); O1–Te–C3, 88.14(22);
O1–Te–C10, 84.91(23).
(157.8 MHz, CDCl3): d = 1102 (s) ppm. ESI-MS: m/z = 1169.3364
(found), 1169.3232 (calculated) for [M+4MeOH+H]+. Anal. Calc. for
C62H42N2O6Te (1038.61): C, 71.70; H, 4.08; N, 2.70. Found: C,
71.50; H, 4.21; N, 2.79%.
4: Reaction medium: 5% methanol–toluene; reflux time: 12 h;
crystallizing solvent: methanol–toluene (1:1). Amounts of starting
materials: (4-MeOC6H4)2TeO, 0.714 (2 mmol) and 4-(pyren-1-
ylmethyleneamino)benzoic acid, 1.39 g (4 mmol). Yield: 1.52 g
(73%). m.p. 176–177 °C. IR (KBr)/cmꢁ1
: masym (C=O): 1703.7, masym
(CH=N): 1606.4. 1H NMR (500 MHz, CDCl3): d 3.69 (s, 6H, OMe),
6.74–8.22 (m, 34H, arom), 9.06 (s, 2H, CH=N) ppm. 13C NMR
(500 MHz, CDCl3):
d 173.0 (OCO), 162.4 (p-anisyl-C), 157.9
(CH=N), 155.0 (ring C attached to N), 57.8 (OMe) ppm. ESI-MS:
m/z = 1174.2976(found), 1174.3075 (calculated) for [M+CH3C6H5+
MeCN+H]+. Anal. Calc. for C62H42N2O6Te (1038.61): C, 71.70; H,
4.08; N, 2.70. Found: C, 71.67; H, 4.29; N, 2.58%.
5: Reaction medium: 5% methanol–toluene; reflux time: 6 h;
crystallizing solvent: methanol–toluene (1:1). Amounts of starting
materials: (4-MeOC6H4)2TeO, 0.715 (2 mmol) and 2-amino benzoic
acid, 0.55 g (4 mmol). Yield: 0.96 g (78%). m.p. 142 °C (d). IR (KBr)/
cmꢁ1 asym (C=O): 1667.4. 1H NMR (500 MHz, CDCl3): d 4.18 (s, 6H,
: m
OMe), 6.73–7.48 (m, 16H, arom), 5.83 (s, br, 4H, NH2) ppm. 13C NMR
(500 MHz, CDCl3): d 172.9 (OCO), 155.7 (p-anisyl-C), 153.6 (C–NH2),
56.0 (OMe) ppm. ESI-MS: m/z = 754.1971 (found), 754.1983 (calcu-
lated) for [M+3MeOH+MeCN+H]+; 617.0936 (found), 617.0931 (cal-
culated) for [M+H]+. Anal. Calc. for C28H26N2O6Te (614.12): C, 54.76;
H, 4.27; N, 4.56. Found: C, 54.47; H, 4.37; N, 4.67%.
Fig. 5. Centrosymmetric dimeric unit formed in 12 through interesting bifurcated
reciprocatory Te ꢀ ꢀ ꢀ O7(NO2), 3.526(6) and Te ꢀ ꢀ ꢀ O8 (NO2), 3.130(6) Å interactions.
6: Reaction medium: 5% methanol–toluene; reflux time: 8 h;
crystallizing solvent: chloroform–methanol (1:1). Amounts of
starting materials: (4-MeOC6H4)2TeO, 0.715 (2 mmol) and 4-amino
benzoic acid, 0.55 g (4 mmol). Yield: 1.04 g (85%). m.p. 137–138 °C.
1: Reaction medium: 1% methanol-toluene; reflux time: 6 h;
crystallizing solvent: benzene–toluene–dichloromethane (1:1:1).
Amounts of starting materials: (4-MeOC6H4)2TeO, 0.714 (2 mmol)
and 2,2-bis(3,5-dimethylpyrazol-1-yl)acetic acid, 0.98 g (4 mmol).
IR (KBr)/cmꢁ1 masym (C=O): 1646.6. 1H NMR (500 MHz, CDCl3): d
:
4.01 (s, 6H, OMe), 6.93–8.06 (m, 16H, arom), 5.78 (s, 4H, NH2)
ppm. 13C NMR (500 MHz, CDCl3): d 170.1 (OCO), 158.8 (p-anisyl-
C), 152.8 (C-NH2), 55.5 (OMe) ppm. ESI-MS: m/z = 653.1152
(found), 653.1143 (calculated) for [M+2H2O+H]+; 425.0611 (found),
425.0608 (calculated) for [M–(4-NH2C6H4COO)2+2MeOH+OH]+.
Anal. Calc. for C28H26N2O6Te (614.12): C, 54.76; H, 4.27; N, 4.56.
Found: C, 54.53; H, 4.41; N, 4.23%.
Yield: 1.04 g (62%). m.p. 115–116 °C. IR (KBr)/cmꢁ1
:masym (C=O):
1729.5. 1H NMR (500 MHz, CDCl3): d 1.98 (12H, 5-CH3), 2.11
(12H, 3-CH3), 3.75 (s, 6H, OMe), 5.72 (s, 4H, CH-pyrazole), 6.71 (s,
2H, CH), 6.80–7.59 (m, 8H, arom) ppm. 13C NMR (500 MHz, CDCl3):
d 176.6 (C=O), 161.9 (p-anisyl-C), 148.1 (C3-pyrazole), 142.5 (C5-
pyrazole), 109.4 (C4-pyrazole), 56.6 (OMe), 14.1 (Me) ppm. 125Te
NMR (157.8 MHz, CDCl3): d = 1033 (s) ppm. ESI-MS: m/z =
7: Reaction medium: 5% methanol-toluene; reflux time: 8 h;
crystallizing solvent: methanol–toluene (1:1). Amounts of starting

V. Chandrasekhar et al. / Polyhedron 52 (2013) 1362–1368
1367
materials: (4-MeOC6H4)2TeO, 0.715 (2 mmol) and 3,5-diamino
13: Reaction medium: toluene; reflux time: 14 h; crystallizing
solvent: methanol–toluene (1:1). Amounts of starting materials:
(4-MeOC6H4)2TeO, 0.715 (2 mmol) and 2-(bezylideneamino)phe-
nol, 0.79 g (4 mmol). Yield: 0.89 g (61%). m.p. 178 °C (d). IR (KBr)/
benzoic acid, 0.61 g (4 mmol). Yield: 0.94 g (73%). m.p. 158 °C. IR
(KBr)/cmꢁ1 masym (C=O): 1682.3. 1H NMR (500 MHz, CDCl3): d
:
3.89 (s, 6H, OMe), 6.68–8.22 (m, 14H, arom), 5.85 (s, 8H, NH2)
ppm. 13C NMR (500 MHz, CDCl3): d 174.7 (OCO), 157.2 (p-anisyl-
C), 148.1 (C-NH2), 56.5 (OMe) ppm. ESI-MS: m/z = 803.2302
(found), 803.2300 (calculated) for [M+2MeCN+CH3C6H5+H]+;
513.0672 (found), 513.0669 (calculated) for [M–(3,5-(NH2)2C6H3
COO)+H2O]+. Anal. Calc. for C28H28N4O6Te (644.15): C, 52.21; H,
4.38; N, 8.70. Found: C, 52.43; H, 4.40; N, 8.57%.
cmꢁ1 masym (CH=N): 1586.2. 1H NMR (500 MHz, CDCl3): d 3.81 (s,
:
6H, OMe), 6.87–8.44 (m, 26H, arom), 9.13 (s, 2H, CH=N). 13C NMR
(500 MHz, CDCl3): d 162.3 (p-anisyl-C), 159.7 (CH=N), 156.7 (O–
C), 145.9 (ring C attached to N), 55.5 (OMe) ppm. ESI-MS:
m/z = 893.2812 (found), 893.2809 (calculated) for [M+2MeOH+CH3
C6H5+H]+; 645.1592(found), 645.1608 (calculated) for [M–(PhCH=
NPhO)+2MeOH+MeCN]+. Anal. Calc. for C40H34N2O4Te (734.31): C,
65.43; H, 4.67; N, 3.81. Found: C, 65.63; H, 4.51; N, 3.89%.
8: Reaction medium: 5% methanol–toluene; reflux time: 12 h;
crystallizing solvent: methanol–toluene (1:1). Amounts of starting
materials: (4-MeOC6H4)2TeO, 0.715 (2 mmol) and 3-nitro benzoic
acid, 0.67 g (4 mmol). Yield: 0.92 g (68%). m.p. 112–113 °C. IR
14: Reaction medium: toluene; reflux time: 14 h; crystallizing
solvent: methanol–toluene (1:1). Amounts of starting materials:
(4-MeOC6H4)2TeO, 0.715 (2 mmol) and 2-[(4-methylphenyl)imi-
nomethyl]-phenol, 0.84 g (4 mmol). Yield: 0.84 g (55%). m.p.
(KBr)/cmꢁ1 masym (C=O): 1680.3. 1H NMR (400 MHz, CDCl3): d
:
3.79 (s, 6H, OMe), 6.91–8.32 (m, 16H, arom) ppm. 13C NMR
(500 MHz, CDCl3): d 173.8 (OCO), 157.2 (p-anisyl-C), 145.6 (C–
NO2), 53.9 (OMe) ppm. ESI-MS: m/z = 718.0731 (found), 718.0680
(calculated) for [M+MeCN+H]+; 675.1392 (found), 675.1350 (calcu-
lated) for [M–(3-NO2C6H4COO)+MeCN+MeOH+CH3C6H5]+. Anal.
Calc. forC28H22N2O10Te (674.08): C, 49.89; H, 3.29; N, 4.16. Found:
C, 50.42; H, 3.21; N, 4.04%.
:
156–158 °C. IR (KBr)/cmꢁ1 masym (CH=N): 1581.4. 1H NMR
(500 MHz, CDCl3): d 2.36 (s, 6H, Me), 3.87 (s, 6H, OMe), 6.59–
8.72 (m, 24H, arom), 9.22 (s, 2H, CH=N). 13C NMR (500 MHz,
CDCl3): d 161.8 (p-anisyl-C), 160.2 (CH=N), 158.8 (O–C), 148.6 (ring
C attached to N), 56.5 (OMe), 22.1 (Me) ppm. 125Te NMR (157.8
MHz, CDCl3): d = 992 (s) ppm. ESI-MS: m/z = 847.2569 (found),
847.2602 (calculated) for [M+2MeOH+H2O+H]+. Anal. Calc. for
9: Reaction medium: 5% methanol–toluene; reflux time: 12 h;
crystallizing solvent: 10% methanol–toluene. Amounts of starting
materials: (4-MeOC6H4)2TeO, 0.715 (2 mmol) and 4-nitro benzoic
acid, 0.55 g (4 mmol). Yield: 0.98 g (73%). m.p. 131 °C. IR (KBr)/
C42H38N2O4Te (762.36): C, 66.17; H, 5.02; N, 3.67. Found: C,
66.48; H, 4.89; N, 3.75%.
cmꢁ1 masym (C=O): 1691.6. 1H NMR (400 MHz, CDCl3): d 3.53 (s,
:
4.3. X-ray crystallography
6H, OMe), 6.85–8.11 (m, 16H, arom) ppm. 13C NMR (500 MHz,
CDCl3): d 170.5 (OCO), 159.7 (p-anisyl-C), 143.3 (C-NO2), 52.6
(OMe) ppm. ESI-MS: m/z = 741.0943 (found), 741.0939 (calculated)
for [M+2MeOH+H]+. Anal. Calc. forC28H22N2O10Te (674.08): C,
49.89; H, 3.29; N, 4.16. Found: C, 49.63; H, 3.33; N, 4.28%.
All measurements for 1, 5, 8, 9, 10, 11 and 12 were made on CCD
Bruker SMART APEX diffractometer. Crystallographic data and
refinement parameters are summarized in Table 1. Data were col-
lected [at 273(2) K, 5, 10 and 11; 100(2) K, 1, 8, 9 and 12] using
10: Reaction medium: 5% methanol–toluene; reflux time: 8 h;
crystallizing solvent: methanol–toluene (1:1). Amounts of starting
materials: (4-MeOC6H4)2TeO, 0.715 (2 mmol) and 3,5-dinitro ben-
zoic acid, 0.85 g (4 mmol). Yield: 1.21 g (79.2%). m.p. 122–124 °C.
graphite-monochromated Mo K
a radiation (ka = 0.71073 Å). The
program SMART [25] was used for collecting frames of data, indexing
reflection, and determining lattice parameters, SAINT [25] for inte-
gration of the intensity of reflections and scaling, SADABS [26] for
absorption correction and SHELXTL [27–28] for space group and
structure determination. Full-matrix least-squares refinements on
F2, using all data, were carried out with anisotropic displacement
parameters applied to all non-hydrogen atoms. Hydrogen atoms
were included in geometrically calculated positions using a riding
model and were refined isotropically. The figures were created
using DIAMOND 3.1d software [29].
IR (KBr)/cmꢁ1 masym (C=O): 1644.9. 1H NMR (500 MHz, CDCl3): d
:
3.60 (s, 6H, OMe), 6.78–8.29 (m, 14H, arom) ppm. 13C NMR
(500 MHz, CDCl3): d 172.4 (OCO), 151.5 (p-anisyl-C), 141.2, 141.5
(C–NO2), 57.6 (OMe) ppm. ESI-MS: m/z = 858.0744 (found),
858.0750 (calculated) for [M+MeCN+MeOH+H2O+H]+. Anal. Calc.
for C28H20N4O14Te (764.08): C, 44.01; H, 2.64; N, 7.33. Found: C,
43.87; H, 2.59; N, 7.50%.
11: Reaction medium: 1% methanol–toluene; reflux time: 9 h;
crystallizing solvent: toluene. Amounts of starting materials: (4-
MeOC6H4)2TeO, 0.715 (2 mmol) and cyclohexylcarboxylic acid,
Acknowledgement
0.51 g (4 mmol). Yield: 1.04 g (87%). m.p. 102 °C. IR (KBr)/cmꢁ1
:
masym (C=O): 1640.6. 1H NMR (400 MHz, CDCl3): d 1.07–2.13 (22H,
cyclohexyl), 3.79 (s, 6H, OMe), 6.89–7.68 (m, 8H, arom) ppm. 13C
NMR (500 MHz, CDCl3): d 181.9 (C=O), 161.6 (p-anisyl-C), 134.6
(m-anisyl-C), 126.0 (C–Te), 115.0 (o-anisyl-C), 55.3 (OMe), 44.2
(1-cyclohexyl-C), 29.3 (2- &6-cyclohexyl-C), 25.8 (3- &5-cyclo-
hexyl-C), 25.6 (4-cyclohexyl-C) ppm. 125Te NMR (157.8 MHz,
CDCl3): d = 1079 (s) ppm. ESI-MS: m/z = 709.2373 (found),
709.2384 (calculated) for [M+CH3C6H5+H2O+H]+. Anal. Calc. for
V.C. is thankful to the Department of Science and Technology for
a J.C. Bose fellowship. A.K. and M.D.P. thanks the Department of Sci-
ence and Technology for Fast Track Young Scientist Fellowship.
Appendix A. Supplementary data
CCDC 876589-876595 contain the supplementary crystallo-
graphic data for 1, 5, 8, 9, 10, 11 and 12. These data can be obtained
free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or
e-mail: deposit@ccdc.cam.ac.uk. Supplementary material associ-
ated with this article can be found in the online version, at http://
dx.doi.org/10.1016/j.poly.2012.06.005.
C28H36O6Te (596.18): C, 56.41; H, 6.09. Found: C, 56.67; H, 6.12%.
12: Reaction medium: toluene; reflux time: 8 h; crystallizing
solvent: methanol–toluene (1:1). Amounts of starting materials:
(4-MeOC6H4)2TeO, 0.715 (2 mmol) and 4-nitrophenol, 0.56 g
(4 mmol). Yield: 0.94 g (76%). m.p. 152–153 °C. 1H NMR
(500 MHz, CDCl3): d 3.58 (s, 6H, OMe), 6.61–8.12 (m, 16H, arom)
ppm. 13C NMR (500 MHz, CDCl3): d 164.1 (O–C), 159.1 (p-anisyl-
C), 143.8 (C–NO2) 56.4 (OMe) ppm. ESI-MS: m/z = 671.0867
(found), 671.0884 (calculated) for [M+MeOH+H2O+H]+. Anal. Calc.
for C26H22N2O8Te (618.06): C, 50.53; H, 3.59; N, 4.53. Found: C,
50.34; H, 3.51; N, 4.64%.
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