Synthesis, Spectral Characterization of Four Symmetrical and Unsymmetrical Organotellurium(II) Compounds: O-H...N, CH...π, and CH...O Secondary Interactions in X-Ray Crystal Structures of 4-MeOC6H4TeCH2CH2CH<sub

Article abstract of DOI:10.1002/hc.21262

The condensation of 3-(4-methoxyphenyltelluro)propylamine and bis(3-aminopropyl) telluride with 2-hydroxyacetophenone formed two Schiff's bases 2-[1-(3-(4-methoxyphenyltellanyl)propylimino)ethyl]phenol (1) and Bis 2-[1-(3-iminopropyltellanyl)ethyl]phenol

Full text of DOI:10.1002/hc.21262

Heteroatom Chemistry
Volume 00, Number 0, 2015
Synthesis, Spectral Characterization of Four
Symmetrical and Unsymmetrical
Organotellurium(II) Compounds: O−H. . . N,
CH. . . π, and CH. . . O Secondary Interactions in
X-Ray Crystal Structures of 4-MeOC6H4TeCH2
CH2CH2N═C(CH3)C6H4-2-OH (1) and
Te[CH2CH2CH2N═C(CH3)C6H4-2-OH]2 (2)
Kumar P. Raghavendra,1 Palakshamurthy B. Siddagangaiah,2
and Shailesh Upreti3
1Department of Studies and Research in Chemistry, University College of Science, Tumkur
University, Tumkur, 572 103, India
2Department of Studies and Research in Physics, University College of Science, Tumkur University,
Tumkur, 572 103, India
3Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110 016, India
Received 11 October 2014; revised 8 January 2015
The compound 4 was also characterized by 13C
ABSTRACT: The condensation of 3-(4-methoxy-
DEPT-135 NMR spectrum. The compounds 1 and
3 are unsymmetrical, and 2 and 4 are symmetrical
type of telluroethers. The single crystals of 1 and
2 were grown, and their molecular structures were
phenyltelluro)propylamine and bis(3-aminopropyl)
telluride with 2-hydroxyacetophenone formed two
Schiff’s
bases
2-[1-(3-(4-methoxyphenyltellanyl)
propylimino)ethyl]phenol (1) and Bis 2-[1-(3-
iminopropyltellanyl)ethyl]phenol (2), respectively.
The reduction of 1 and 2 gave compounds 2-[1-(3-
(4-methoxyphenyltellanyl)propylamino)ethyl]phenol
(3) and Bis 2-[1-(3-aminopropyltellanyl)ethyl]phenol
(4), respectively. These four new organotellurium
determined by single crystal X-Ray diffraction. The
˚
ArC–Te bond length in 1 was found 2.117(7) A. The
˚
RC–Te bond length in 1 is 2.141(5) A and in 2 is
˚
2.146(5) and 2.150(6) A. The > C═N bond lengths in
˚
1 and 2 were between 1.278(6) and 1.295(6) A. There
exists intramolecular O−H. . . N hydrogen bonding
1
compounds (1–4) were characterized by H and 13C
˚
[between 1.758(4) and 1.792(4) A] in 1 and 2. In
NMR and FTIR spectroscopies and atomic absorption
spectrophotometer (AAS) (Te). The conductance and
molecular weights and composition by elemental
analysis (C, H, and N) of 1 and 2 were determined.
compound 2, these nonbonded interactions result
in the formation of a R22 (34) dimeric ring. CH. . .
˚
O
[2.505(4)–2.516(3) A] in 1 and 2 and CH. . . π [2.61(5)
˚
and 2.89(4) A] secondary interactions are also present
ꢀC
in 2.
2015 Wiley Periodicals, Inc. Heteroatom
Correspondence to: Kumar P. Raghavendra; e-mail: raghukp1
@gmail.com.
Chem. 00:1–9, 2015; View this article online at
wileyonlinelibrary.com. DOI 10.1002/hc.21262
Supporting Information is available in the online issue at
www.wileyonlinelibrary.com.
ꢀC
2015 Wiley Periodicals, Inc.
1

2
Raghavendra, Palakshamurthy, and Upreti
INTRODUCTION
[14] was carried out on a Perkin–Elmer Analyst
100 atomic absorption spectrophotometer (AAS)
(Massachusetts, USA). The molecular weights were
determined in chloroform at different concentra-
tions (generally 5–10 mM) by a KNAUER vapor pres-
sure osmometer (model no. A-0280) (Berlin, Ger-
many) in which benzil was used as a calibration
The increased interest in the synthesis and structural
characterization of organotellurium compounds
for the past three decades has been due to their
enhanced applications in various fields of science.
These compounds have been used in organic chem-
istry as excellent synthons [1], biochemistry [2],
toxicological studies [3], photography [4], the
synthesis of polymers as reagents [5] and insecti-
cides [6], and coordination chemistry as ligands [7].
Pd(II) complexes of hybrid ligands containing tel-
lurium as a soft donor along with hard donors (N/O)
have been used as catalysts in organic reactions such
as Suzuki–Miyaura and Heck C−C cross-coupling
reactions [8]. However, despite their potential
applications, their wide utilization in diverse areas
has largely been restricted due to their fewer
synthetic methodologies, difficulty in purification,
weak C−Te bond, and their unstable nature. The
organotellurium compounds are stabilized by for-
mation of supramolecular structures via secondary
interactions [9]. Therefore, it would be worth to
synthesize organotellurium compounds having
secondary interaction, which can stabilize them and
can act as hybrid ligands as their Pd(II) complexes
can be used as excellent catalysts in C−C coupling
reaction in organic synthesis. Therefore, herein we
report the synthesis of four new organotellurium
compounds 1–4 by simple Schiff base condensation
and reduction protocol, their characterization,
and single crystal X-ray structures of 2-[1-(3-(4-
methoxyphenyltellanyl)propylimino)ethyl]phenol
(1) and Bis 2-[1-(3-iminopropyltellanyl)ethyl]phenol
(2). The molecular structure of 1 and 2 contain
intramolecular O−H···N hydrogen bonding and
CH. . . O and CH. . . π secondary interactions.
standard (accuracy
5.0 amu). The 1H and 13C
NMR (Bruker, USA) spectra were recorded on a
Bruker Spectrospin DPX-300 NMR spectrometer at
300.13 and 75 MHz, respectively. FTIR spectra in the
range of 4000–250 cm−1 were recorded on a Nicolet
Prote´ge 460 FT-IR (NICODOM Ltd., Hlavni, Czech
Republic, EU) spectrometer as KBr pellets. The melt-
ing points were determined in open capillary tubes
and are reported as such. The molar conductance
(ꢀM) measurements were carried out in CH3CN
(concentration ca 1 mM) using the ORION conduc-
tivitymeter model 162 (Cole-Parmer India Pvt. Ltd.,
Powai, Mumbai, India).
X-Ray Data Collection and Structure Refinement
Details
The single crystal X-ray diffraction data of 1 and
2 were collected at IIT Delhi, New Delhi, India, on
a Bruker SMART CCD diffractometer with Mo Kα
˚
(λ = 0.71073 A) X-radiations at 25°C. Crystal struc-
tures of 1 and 2 were solved using SHELXTL [15].
The software SADABS was used for absorption cor-
rections and SHELXTL for space group, structure
determination, and refinements [15, 16]. All non-
hydrogen atoms were located from the difference
Fourier map using geometrical constraints and were
refined anisotropically. The least-squares refine-
ment cycles on F2 were performed until the model
converged.
EXPERIMENTAL
Chemicals
Synthesis of 4-MeOC6H4TeCH2CH2CH2N═
C(CH3)C6H4-2-OH (1)
3-Chloropropylamine hydrochloride and 2-hydroxy
acetophenone were procured from Merck (India)
and Aldrich (USA), respectively, and used as re-
ceived. All the solvents were purchased from
Merck (India) and used after purification. Bis(4-
methoxyphenyl) ditelluride [10], disodium telluride
(Na2Te) [11], bis(3-aminopropyl)telluride [12] and
3-(4-methoxyphenyltelluro)propylamine [13] were
synthesized as per the reported methods.
2-(4-Methoxyphenyltelluro) propyl amine (1.47 g,
5.0 mmol) was stirred for 0.5 h in 20 mL
of dry ethanol at room temperature. o-Hydro-
xyacetophenone (0.6 mL, 5.0 mmol) dissolved in
20 mL of dry ethanol was added to the above solu-
tion dropwise with stirring. The mixture was stirred
for further 1–2 h at room temperature. The solution
was concentrated on a rotary evaporator, resulting
in a yellow precipitate. The precipitate was filtered,
and on recrystallization from a 1:1 mixture of chlo-
roform and hexane gave yellow single crystals of 1.
Yield: 80%; mp: 85–86°C; ꢀM = 0.7 S cm2
mol−1. Elemental analyses: Found (Calcd.) for
C18H21NO2Te: C, 52.61 (52.61), H, 5.16 (5.15), N,
3.45 (3.41), Te, 31.00 (31.05); Molecular weight:
Analytical Methods
The C, H, and N analyses were carried out us-
ing a Perkin–Elmer elemental analyzer 240 C
(Massachusetts, USA). The tellurium estimation
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Spectral Characterization of Four Symmetrical and Unsymmetrical Organotellurium(II) Compounds
3
SCHEME 1 Synthesis of organotellurium compounds 1–4.
1
C22H28N2O2Te: C, 54.94 (55.04), H, 5.86 (5.88), N,
5.69 (5.84), Te, 26.04 (26.58); Molecular weight:
Found (Calcd.), 480 (481); NMR: H (CDCl3, 25°C):
Found (Calcd.), 411 (413); NMR: H (CDCl3, 25°C):
δ (vs. TMS): 2.19 (quintet, J = 5.7 Hz, 2H, H2),
2.26 (s, 3H, CH3), 2.95 (t, J = 5.8 H,z 2H, H3), 3.75
(s, 3H, OCH3), 3.59 (t, J = 6.3 Hz, 2H, H1), 6.70–6.73
(d, J = 8 Hz, 2H, ArH m to Te), 6.75 (t, J = 7 Hz, 1H,
H8), 6.89–6.93 (d, J = 8.4 Hz, 1H, H10), 7.27 (t, J =
6.9 Hz, 1H, H9), 7.46–7.48 (d, J = 8.1 Hz, 1H, H6),
7.66–7.68 (d, J = 8.4 Hz, 2H, ArH o to Te), 16.50 (bs,
1H, OH); 13C (CDCl3, 25°C): δ (vs. TMS): 5.96 (C2),
14.44 (CH3), 31.96 (C3), 50.33 (C1), 55.14 (OCH3),
100.14 (ArC−Te), 115.22 (ArC m to Te), 116.82
(C7), 118.83 (C7), 119.34 (C5), 127.93 (C10), 132.51
(C8), 140.93 (ArC o to Te), 159.82 (ArC−OCH3), 164.3
(C6), 171.93 (C4); FTIR (KBr, cm−1): 1645 (>C═N),
292, Te−C(aryl), 504, Te−C(alkyl).
1
δ (vs. TMS): 2.18 (quintet, J = 6.6 Hz, 2H, H2), 2.33
(s, 3H, CH3), 2.79 (t, J = 6.9 Hz, 2H, H3), 3.61 (t,
J = 5.4 Hz, 2H, H1), 6.75 (t, J = 7.2 Hz, 1H, H8),
6.89–6.91 (d, J = 8.1 Hz, 1H, H10), 7.27 (t, J =
7.4 Hz, 1H, H9), 7.47–7.50 (d, J = 7.8 Hz, 1H, H6),
16.50 (bs, 1H, OH); 13C (CDCl3, 25°C): δ (vs. TMS):
1.06 (C2), 14.37 (CH3), 32.45 (C3), 50.48 (C1), 116.83
(C7), 118.74 (C9), 130.62 (C5), 127.91 (C10), 136.42
(C8), 164.26 (C6), 171.95 (C4); FTIR (KBr, cm−1):
1650 (>C═N), 292, Te−C(aryl), 518, Te−C(alkyl).
Synthesis of
4-MeOC6H4TeCH2CH2CH2NHCH(CH3)C6H4-2-
OH (3) and Te[CH2CH2CH2NHCH(CH3)C6H4-
2-OH]2 (4)
Synthesis of Te[CH2CH2CH2N═
C(CH3)C6H4-2-OH]2 (2)
Bis(3-aminopropyl)telluride
(0.4678/0.5375
g,
The compounds 1 or 2 (0.413 g/0.480 g, 1 mmol) and
NaBH4 (0.38 g, 10 mmol) was refluxed for 24 h in
100 mL dry ethanol. The solution was cooled,
and the solvent was evaporated on a rotary
evaporator and dried under vacuum result-
2.5 mmol) was stirred for 0.5 h in 20 mL of
dry ethanol at room temperature. 2-Hydroxy-
acetophenone (0.6 mL, 5 mmol) dissolved in
20 mL of dry ethanol was added to the above
solution dropwise with stirring. The mixture was
stirred at room temperature for further 6 h and kept
at 0–5°C for 24 h. The compound 2 was separated
as a yellow precipitate. The precipitate was filtered,
and on recrystallization at 0–5°C from a 1:1 mixture
of chloroform and hexane gave single crystals of 2.
Yield: 70%;mp: 95–96°C; ꢀM = 0.9 S cm2
mol−1. Elemental analyses: Found (Calcd.) for
ing in
a residue. The compound 2-[1-(3-(4-
methoxyphenyltellanyl)propylamino)ethyl]phenol
(3) or Bis 2-[1-(3-aminopropyltellanyl)ethyl]phenol
(4) was extracted into dichloromethane (100 mL)
from the residue obtained. The solution was dried
with anhydrous sodium sulfate. On removing the
solvent using rotary evaporator, 3 or 4 was obtained
as highly viscous colorless oils.
Heteroatom Chemistry DOI 10.1002/hc

4
Raghavendra, Palakshamurthy, and Upreti
FIGURE 1 13C DEPT-135 NMR spectrum of 4-MeOC6H4TeCH2CH2CH2NHCH(CH3)C6H4-2-OH (4).
Compound 3. Yield: 80%; ꢀM = 0.8 S cm2 mol−1
.
and acetone but insoluble in diethyl ether and
hexane.
Te, 30.86 (30.90); NMR: 1H (CDCl3, 25°C): δ (vs.
TMS): 1.27–1.29 (d, J = 6.6 Hz, 3H, CH3), 1.78–1.88
(quintet, J = 7.1 Hz, 2H, H2), 2.46–2.57 (m, 2H, H3),
2.59–2.74 (m, 2H, H1), 3.68 (s, 3H, OCH3), 3.69–3.77
(q, J = 7.7 Hz, 1H, H4), 6.64–6.66 (d, 2H, J = 7.4 Hz,
ArH m to Te), 6.68 (t, J = 6.9 Hz, 1H, H8), 6.80–6.83
(d, J = 8.4 Hz, 1H, H10), 7.03 (t, J = 7.8 Hz, 1H,
The molar conductance was measured for all
the compounds in acetonitrile at the ꢀ1 mM con-
centration level at room temperature (25°C). The
found molar conductance is much lower than the
values expected for a 1:1 electrolyte (120–160 S cm2
mol−1) [17]. This suggests that all the compounds
are nonelectrolytes and do not dissociate apprecia-
bly. These observations are further supported by the
molecular weights of the compounds 1 and 2. The
molecular weights were also found to be consistent
with their monomeric nature in solution.
The FTIR spectra of 1 and 2 are characteris-
tic and showed >C═N stretching vibrations [18] at
1645 and 1650 cm−1, respectively, whereas these
bands were absent in the IR spectra of 3 and 4. The
Te−C (alkyl) stretching vibrations were observed in
the IR spectra at 504–520 cm−1, whereas those of
Te−C(aryl) appear at 282–292 cm−1, which are com-
parable with the literature values [19].
H9), 7.55–7.57 (d, 3H, J = 8.4 Hz, H6 and H12,16); 13
C
(CDCl3, 25°C): δ (vs. TMS): 6.25 (C2), 22.26 (CH3),
31.52 (C3), 48.81 (C1), 55.04 (OCH3), 58.95 (C4).
100.07 (ArC−Te), 115.13 (ArC m to Te), 116.54 (C7),
118.81 (C9), 126.51 (C5), 127.92 (C10), 128.94 (C8),
141.13 (ArC o to Te), 157.12 (ArC−OCH3), 159.72
(C6), 171.93; FTIR (KBr, cm−1): 3487, 1545 (N−H);
283, Te−C(aryl); 520, Te−C(alkyl).
Compound 4. Yield: 75%; ꢀM = 0.9 S cm2
1
mol−1. Te, 26.33 (26.36); NMR: H (CDCl3, 25°C): δ
(vs. TMS): 1.35–1.38 (d, J = 6.8 Hz, 3H, CH3), 1.75–
1.86 (quintet, J = 6.6 Hz, 2H, H2), 2.45–2.76 (m, 4H,
H1,3), 3.69- 3.77 (q, J = 7.6 Hz, 1H, H4), 6.68 (t, J =
8.0 Hz, 1H, H8), 6.80–6.83 (d, J = 8.4 Hz, 1H, H10),
7.03 (t, J = 7.6 Hz, 1H, H9). 11.76 (bs, 1H, OH).
13C (CDCl3, 25°C): δ (vs.. TMS): –2.04 (C2), 22.10
(CH3), 31.80 (C3), 48.91 (C1), 58.83 (C4), 116.33 (C7),
118.72 (C9), 126.32 (C5), 127.74 (C10), 127.93 (C8),
156.81 (C6); FTIR (KBr, cm−1): 3406, 1578 (N−H);
282, Te−C(aryl); 512, Te−C(alkyl).
The 1H and 13C NMR spectra of organotellurium
compounds 1–4 are characteristic [20]. A highly
deshielded (due to intramolecular OH. . . N hydrogen
bonding) singlet at 16.00 ppm was assigned to Ar-
OH proton in 1 and 2, whereas the signal for these
protons in 3 and 4 was appeared at 11.40 ppm as a
very broad singlet.
In 1H and 13C NMR spectra of 3 and 4 CH3
protons CH proton couple each other and appeared
as doublet at 1.27 and a quartet at 3.69–3.76 ppm,
respectively.
RESULTS AND DISCUSSION
In 13C NMR spectrum of 3 the C5 and CH3 car-
bon signals are deshielded by 7.20 and 7.86 ppm,
respectively. The C1 carbon signal was shielded by
1.5 ppm, whereas C4 signal was deshielded by about
113 ppm, respectively, relative to the respective car-
bon signals of 1. This large shielding of C4 carbon
The organotellurium compounds 1–4 were synthe-
sized as per the reactions given in Scheme 1.
Organotellurium compounds 1 and 2 are yellow
crystalline solids, whereas 3 and 4 are colorless vis-
cous liquids. The compounds 1–4 are freely soluble
in chloroform, dichloromethane, ethanol, methanol-
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Spectral Characterization of Four Symmetrical and Unsymmetrical Organotellurium(II) Compounds
5
TABLE 1 Crystal Data and Structure Refinement Parameters for 1 and 2
Characteristic
Empirical formula
Formula weight
Color
Crystal size, mm3
Crystal system
Space group
1
2
C22H28N2O2Te
480.06
C18H21NO2Te
410.96
Yellow
Yellow
0.319 × 0.21 × 0.049
Monoclinic
P21/c
0.392 × 0.219 ×0.042
Monoclinic
P21/c
˚
˚
Unit cell dimensions
a = 19.0344(18) A
a = 7.9931(15) A
˚
˚
b = 6.6866(6) A
b = 12.428(2) A
˚
˚
c = 14.2601(14) A
c = 21.433(4) A
α = γ = 90°,
α = γ = 90°,
β = 105.761(2)°
β = 100.75(2)°
˚
V, A3
1746.7(3)
2091.8(7)
4
Z
4
ρ, (calcd.), mg/m3
μ, mm–1
F(000)
θ, range (°)
Index ranges
1.563
1.71
816
1.1–25.50
–22 ࣘ h ࣘ 23
–8 ࣘ k ࣘ 8,
–17 ࣘ l ࣘ 17
12,596
1.524
1.441
968
1.90–25.0
–9 ࣘ h ࣘ 9
–14 ࣘ k ࣘ 14
–25 ࣘ l ࣘ 25
14,891
Reflections collected
Independent reflections
Completeness to max. θ, %
Maximum and minimum transmission
Data/restraints/parameters
Goodness-of-fit on F2
3685[R(int) = 0.0841]
3242[R(int) = 0.0323]
99.9
99.8
0.655 and 0.922
3242/0/202
1.054
0.689 and 0.943
3685/0/226
1.162
Final R indices [I > 2σ(I)]
R indices (all data)
R1 = 0.0568, wR2 = 0.121
R1 = 0.0631, wR2 = 0.133
R1 = 0.0805, wR2 = 0.132
R1 = 0.0793, wR2 = 0.142
˚
Largest difference peak and hole, e A-3
0.88 and −0.59
0.89 and −0.46
is due to transformation from imine (−C4═N−) into
amine (−C4H−NH−). The signal for C3 carbon was
observed at 31.96 ppm in 1, but this signal was
shielded by 0.5 ppm in 3. In the 13C NMR spectrum
of 4, the C1 and C3 carbon signals were shielded by
1.0–2.0 ppm, whereas the CH3 and C4 signals were
shielded by about 8 and 70 ppm, respectively, when
compared to the respective carbon signals in 2. The
compound 4 was also characterized by 13C DEPT-
135 NMR spectrum (Fig. 1) in which the CH2 signals
were observed directing toward the base line, the
CH and CH3 signals directing upward and the qua-
ternary carbon peaks were absent.
The crystal data and refinement parameters for 1
and 2 are given in Table 1, and selected bond lengths
and bond angles of 1 and 2 are given in Table 2.
The O−H. . . N intramolecular hydrogen bonding and
CH. . . π and CH. . . O secondary interactions of 1 and
2 are given in Table 3.
C(5)–Te(1)–C(8) bond angle of 1 (96.00 (2)o) is
slightly wider than the value [94.96(14)°] re-
ported for N-[2-(4-methoxyphenyltelluro) propyl]
phthalimide [21] and slightly narrower than
the value [98.8(3)°] reported for N-[2-(4-methoxy
phenyltelluro)ethyl]benzamide [21], which may be
due to longer alkyl chain and the N(11)═C(1) bond
˚
length is 1.295(6) A, which is consistent with the lit-
erature value reported for similar Schiff base com-
pound 4-MeOC6H4TeCH2CH2N=C(CH3)C6H4-2-OH
[22].
In the crystal of 1, there exists an O(2)
−H(2). . . N(1) [1.758(4) A] intramolecular hydro-
˚
gen bonding and the molecules are stabilized
by two C(12) −H(12C). . . O(2) [2.516(3) A] and
˚
C(14) −H(14). . . O(2) [2.519(3) A] intermolecular
˚
secondary interactions as shown in Fig. 3.
The molecular structure of 2 is shown in
Fig. 4. The Te−C(alkyl) bond lengths in 2 are
˚
The ORTEP diagram of
1
is shown in
2.150(6) and 2.146(5) A [Te(1)–C(1) and Te(1)–C(12),
Fig. 2. In compound 1, Te−C(alkyl) [Te(1)–C(12),
2.141(5)] bond length is longer than Te−C(aryl)
[Te(1)–C(1), 2.117(7)] and these values are com-
parable with the values [2.140(8) and 2.107(8),
respectively] reported for the compound, N-[2-
(4-methoxyphenyltelluro)ethyl]benzamide [21]. The
respectively]. The C–Te–C bond angle of 2 is 94.6(2)°.
All are consistent with the reported values of N-[2-
(4-methoxyphenyltelluro)propyl]phthalimide [21].
In tellurated Schiff base ligand 2, there
are two intramolecular hydrogen bonds, O(1)
−H(1)···N(1) [1.761(4)] and O(2) −H(2)···N(2)
Heteroatom Chemistry DOI 10.1002/hc

6
Raghavendra, Palakshamurthy, and Upreti
˚
TABLE 2 Selected Bond Lengths (A) and Bond Angles (°) of 1 and 2
˚
Bond Lengths (A)
1
2
Te(1)–C(5)
Te(1)–C(8)
N(1)–C(10)
N(1)–C(11)
O(1)–C(1)
O(1)–C(2)
C(5)–C(6)
2.117(7)
2.141(5)
1.459(7)
1.295(6)
1.409(9)
1.366(8)
1.373(7)
1.486(7)
1.758(4)
Te(1)–C(1)
N(1)–C(3)
N(2)–C(14)
C(12)–C(13)
Te(1)–C(12)
N(1)–C(4)
2.150(6)
1.473(7)
1.458(6)
1.520(7)
2.146(5)
1.278(6)
1.283(6)
1.760(15)
1.792(4)
N(2)–C(15)
C(11)–C(12)
O(2)–H(2)···N(1)
O(1)–H(1)···N(1)
O(2)–H(2)···N(2)
Bond Angles (°)
C(5)–Te(1)–C(8)
N(1)–C(10)–C(9)
C(11)–N(1)–C(10)
C(9)–C(8)–Te(1)
C(6)–C(5)–Te(1)
C(4)–C(5)–Te(1)
N(1)–C(11)–C(13)
N(1)–C(11)–C(12)
96.00(2)
109.57(4)
122.5(4)
113.7(4)
122.3(5)
120.1(5)
116.9(4)
121.5(5)
C(4)–N(1)–C(3)
C(13)–C(12)–Te(1)
C(8)–C(9)–C(10)
N(2)–C(14)–C(13)
C(12)–Te(1)–C(1)
C(15)–N(2)–C(14)
C(20)–C(21)–C(16)
C(2)–C(1)–Te(1)
123.5(5)
113.6(4)
119.9(6)
111.9(4)
94.6(2)
122.3(4)
121.9(5)
114.4(4)
TABLE 3 Secondary Interactions of 1 and 2
D−H···A
D−H
H···A
D···A
D−H···A
Compound 1
2.516(3)
C12−H12C···O2i
C14−H14···O2i
O2−H2···N1ii
0.960(6)
0.930(5)
0.820(4)
3.369(6)
3.419(6)
2.492(6)
148.08(0.34)
162.98(0.34)
148.06(0.30)
2.519(3)
1.758(4)
Symmetry code: (i) x, y + 1, z; (ii) x, y, z
Compound 2
C21−H21···O1i
0.930(5)
2.505(4)
1.761(4)
1.792(4)
2.61(5)
3.430(7)
2.4971(6)
2.506(5)
3.534(7)
3.569(6)
173.48(0.35)
147.57(0.30)
144.76(0.30)
151.89(0.11)
135.73(0.33)
O1−H1···N1ii
0.820(4)
0.820(4)
0.960(6)
0.960(6)
O2−H2···N2 ii
C(11) −H(11A). . . Cπ(2)
C(22) −H(22B). . . Cπ(1)
2.829(4)
Symmetry code: (i) –x + 1, −y + 1, −z + 1; (ii) x, y, z
[1.792(4)], which are also consistent with the
values reported for similar types of Schiff base
compounds 4-MeOC6H4TeCH2CH2N═C(CH3)C6H4-
significance in these compounds as reported for
organotellurium compounds containing −Te−C≡ X
(C and N) groups [23].
2-OH
and
2-HOC6H4(CH3)C═NCH2CH2Te
CH2CH2N═C(CH3)C6H4-2-OH [22]. The inter-
molecular C(21) −H(21). . . O(1) [2.505(4) A]
˚
CONCLUSIONS
secondary interactions forming aR22 (34) dimeric
ring structure of 2 are shown in Fig. 5. In crystal
packing of 2, a pair of C(11) −H(11A). . . Cπ(2)
Four new organotellurium compounds were syn-
thesized by simple Schiff’s base condensation (1
and 2) and reduction by sodium borohydride (3 and
4). Compounds 1–4 were characterized by spectro-
scopic methods and conductance measurement, and
the amount of tellurium was determined by AAS,
the composition by elemental analysis and molec-
ular weights of 1 and 2 were also determined. The
single crystal structures of 1 and 2 were determined
by X-ray diffraction. In the crystal structure of 1 and
[2.61(5) A] and C(22) −H(22B). . . Cπ(1) [2.829(4)
˚
˚
A] secondary interactions exists where Cπ(1) and
Cπ(2) are the centroids for the ring C(5)–C(10)
and C(16)–C(21), respectively, as shown in Fig. 6.
The Te. . . Te (4.566 A) distance between the two
˚
nearest molecules of 2 is greater than the sum
˚
of their vander Waal’s radii (4.40 A); therefore,
this type of Te. . . Te secondary interactions has no
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Spectral Characterization of Four Symmetrical and Unsymmetrical Organotellurium(II) Compounds
7
FIGURE 2 ORTEP diagram of 4-MeOC6H4TeCH2CH2CH2N═C(CH3)C6H4-2-OH (1).
FIGURE 3 Crystal packing with O−H. . . N intramolecular hydrogen bonding and C−H. . . O intermolecular secondary interac-
tions in 1.
FIGURE 4 ORTEP diagram of Te[CH2CH2CH2N═C(CH3)C6H4-2-OH]2 (2).
the formation of the R22 (34) dimeric ring structure
of 2 and a pair of C−H. . . π [2.61(5) and 2.829(4)
2, there exists intramolecular O−H. . . N [1.758(4) A
˚
to 1.792(4)] hydrogen bonds, and the molecules are
stabilized by two intermolecular C−H. . . O [2.505(4)
˚
A] interactions were found in symmetric organ-
˚
otellurium compound 2. These types of secondary
interaction produce supramolecular structures and
and 2.516(3) A] secondary interactions. The
intermolecular C−H. . . O interactions resulting in to
Heteroatom Chemistry DOI 10.1002/hc

8
Raghavendra, Palakshamurthy, and Upreti
FIGURE 5 Crystal packing of 2 with O−H. . . N intramolecular hydrogen bonding and C−H. . . O intermolecular secondary
interactions resulting in to the formation of the R22 (34) dimeric ring structure.
FIGURE 6 Crystal packing of 2 with C−H. . . π intermolecular secondary interactions.
hence increase the stability of less stable organtel-
lurium compounds.
from the Cambridge Crystallographic Data Centre,
12, Union Road, Cambridge CB2 1EZ, UK; fax: (int.)
+44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk].
SUPPLEMENTARY DATA
ACKNOWLEDGMENTS
CCDC numbers 1028609 and 1028526 contain the
supplementary crystallographic data for 1 and 2, re-
spectively. These data can be obtained free of charge
at www.ccdc.cam.ac.uk/conts/retrieving.html [or
RKP thank Prof. Ajai K. Singh, IIT Delhi, New Delhi,
India, for the research guidance during his Ph.D.
thesis and to UGC, New Delhi, India, for Junior and
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Spectral Characterization of Four Symmetrical and Unsymmetrical Organotellurium(II) Compounds
9
D.; Kumar, A.; Singh, A. K. Inorg Chem Commun
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A. K. J Organomet Chem 2014, 749, 1–6.
Senior Research Fellowships. Both authors thank
IIT Delhi for providing necessary laboratory and an-
alytical facilities.
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Heteroatom Chemistry DOI 10.1002/hc