52
P. Singh et al. / Journal of Organometallic Chemistry 731 (2013) 49e54
Table 2
Te/Cl interactions between two independent molecules has also
been observed in the crystal lattice of 1a.
ꢀ
ꢀ
Important bond angles ( ) and bond distances (A) in compounds 2Ba and 3Ba.
2Ba
3Ba
3. Experimental
CeTeeC
TeeCeC
O/TeeCtrans
O/NeCtrans
Te/O
105.52(7)
103.2(1)
157.43(6)
166.3(1)
2.783(2)
2.805(2)
2.132(2)
110.30(7)
103.3(1)
162.63(6)
e
3.1. General procedures
2.895(2)
e
All solvents were purified and dried before use. The starting
materials 2-acetylpyridine, 2-acetylprrole and cyclohexanone were
procured from Merck KGaA, Germany. 1-Naphthyltellurium(IV)
trichloride and mesityltellurium(IV) trichloride were prepared by
the chlorination of their corresponding ditellurides with SO2Cl2.
Tellurium tetrachloride was prepared by earlier reported method
[50]. Melting points were recorded in capillary tubes and are un-
corrected. 1H NMR spectra were recorded at 300.13 MHz in CDCl3
on a Bruker DRX300 spectrometer using Me4Si as the internal
standard. 13C{1H} (100.54 MHz) and 125Te{1H} (126.19 MHz) NMR
spectra were recorded in CDCl3 on a JEOL Eclipse Plus 400 NMR
spectrometer, using Me4Si and Me2Te as internal standards. Mi-
croanalyses were carried out using a Carlo Erba 1108 analyzer.
O/N
TeeC(Ar)
2.133(2)
which also makes the functionalized ligand coplanar with the
equatorial plane.
H
N
N
H
O
O
(II)
(I)
The crystal lattice of mesityl(2-pyrroylmethyl)tellurium(IV)
dichloride (2Ba) is also devoid of such Te/Cl SBIs. Instead, the
presence of more electronegative atoms favors the intermolecular
NeH/O and NeH/Cl H-bonding interactions to become the
dominant supramolecular motifs in the lattice of 2Ba. Pairs of
molecules self-assemble into zero-dimensional centrosymmetric
dimeric units (Fig. S2) to balance the local dipoles which form 3eD
supramolecular arrays by means of CeH/Cl interactions (Fig. S3).
In case of 3Ba, the molecular structure of the unsymmetrical
diorganotellurium(IV) dichloride, the carbonyl O atom is involved
in the intramolecular secondary bonding interaction. The observed
internuclear distance between O and Te atoms, which is shorter
3.2. Syntheses
3.2.1. Compound 1a
Condensation of TeCl4 (0.54 g, 2.0 mmol) with 2-acetylpyridine
(0.45 mL, 4.0 mmol) in refluxing carbontetrachloride (10 mL) for
30 min resulted in a red solid. After cooling, ethanol (15 mL) was
added to it to dissolve the solid and the resulting solution was
refluxed for 2 h. A crystalline compound was obtained from the
solution after 24 h at room temp. Its solution in dichloromethane
(20 mL) was passed through a small silica column and kept for
crystallization to obtain colorless rectangular crystals of 1a. Yield:
0.425 g (60%). M.p.: 180 ꢀC. Anal. Calc. for C7H6ONTeCl3 (354.09): C,
23.74; H, 1.71; N, 3.96. Found: C, 23.71; H, 1.65; N, 3.86. 1H NMR:
ꢀ
than the sum of their van der Waals radii [d(Te, O) ¼ 2.895(2) A;
ꢀ
Srvdw(Te, O) ¼ 3.58 A] and near linearity of the O/TeeCtrans triad
d
4.68 (s, 2H, CH2), 7.98e8.02 (t, 1H, ring proton), 8.29, 8.32 (d, 1H,
(: OeTeeCtrans measure 162.6(1)ꢀ) substantiate the presence of
attractive 1,4-Te/O interaction. This interaction brings the O atom
in to the equatorial C1AeTeeC1B plane, reduces the tetrahedral
angle TeeC1BeC2B to 103.3ꢀ and increases marginally the trans
ring proton), 8.37, 8.39 (d, 1H, ring protons), 8.79, 8.80 (d, 1H, ring
protons) ppm. 13C{1H} NMR:
d 64.8 (CH2), 124.9, 130.9, 142.8, 144.9,
147.3 (ring carbons), 188.8 (CO) ppm. 125Te{1H} NMR:
d 1171 ppm.
ꢀ
TeeC(aryl) bond length [d(TeeC(aryl)) ¼ 2.133(2); cf. 2.103 A in
3.2.2. Unsymmetrical diorganotellurium(IV) dichlorides
ꢀ
Npl2TeCl2 [48] and 2.100(2) A in (2,6-(MeO)2C6H3)2TeCl2 [49].
Compound 2Aa: A solution of 1-naphthyltellurium trichloride
(0.36 g, 1.0 mmol) and 2-acetylpyrrole (0.11 g, 1.0 mmol) in
dichloromethane (25 mL) was stirred at room temperature for 24 h.
The resulting solution was passed through short silica column and
the solvent of the resulting solution was reduced to 10 mL. Addition
of petroleum ether (40e60 ꢀC) afforded 2Aa as a white colored solid
that was recrystallized from dichloromethane to obtain colorless
rectangular crystals. Yield: 0.34 g (78%). M.p.: 164e166 ꢀC dec. Anal.
Calc. for C16H13ONTeCl2 (433.79): C, 44.30; H, 3.02; N, 3.23. Found:
The crystal lattices of 3Ba is devoid of Te/Cl interactions pre-
sumably due to the sterically demanding aryl moiety bonded to the
central tellurium atom. Due to inaccessibility of the Te center to the
atoms of neighboring molecules, no intermolecular associative
force involving Te are present in the lattice of 3Ba. A three-
dimensional supramolecular architecture was realized via Ce
H/Cl interactions is presented in Fig. S4.
2.3.1. Conclusion
C, 44.17; H, 3.13; N, 3.35. 1H NMR:
d 5.51 (s, 2H, CH2), 6.41 (s, 1H,
A
strategy involving electrophilic substitution reaction of
pyrrole ring), 7.14 (s, 1H, pyrrole ring), 7.22 (s, 1H, pyrrole ring),
7.61e7.75 (m, 3H, naphthyl protons), 7.95, 7.98 (d, 1H, naphthyl
proton), 8.07, 8.10 (d, 1H, naphthyl proton), 8.15, 8.18 (d, 1H,
naphthyl proton), 8.26, 8.28 (d, 1H, naphthyl proton), 9.56 (s, 1H,
the ketones (such as 2-acetylpyridine, 2-acetylpyrrole and
cyclohexanone) with tellurium tetrachloride and aryltellurium
trichloride has been used as a direct synthetic route to obtain
2-pyridoylmethyltellurium(IV) trichloride (1a) and aryl(2-pyrro-
lylmethyl)tellurium(IV) dichlorides (2Aa, 2Ba), aryl(2-oxocyclo-
hexyl)tellurium(IV) dichlorides (3Aa, 3Ba) respectively. These
newly synthesized trichloride and dichlorides have been charac-
terized by spectroscopic studies (1H, 13C and 125Te NMR). The
structural aspects of these newly synthesized compounds have
been explored by studying the crystal packing in case of 1a, 2Ba and
3Ba. In crystal lattice of 1a 1,5-Te/N chelation is observed where as
in 2Ba and 3Ba 1,4-Te/O interactions have been noticed. In case of
2Ba 1,4-N/O interaction is also present in addition to (C, O) che-
lation. Formation of dimeric units by means of intermolecular
pyrrole NH proton) ppm. 13C{1H} NMR:
d 64.4 (CH2), 112.1, 119.8,
126.4, 126.9, 127.3, 127.5, 128.2, 129.2, 129.5, 132.0, 132.7, 132.9,
133.6, 134.3 (aromatic carbons), 179.9 (CO) ppm. 125Te{1H} NMR:
d
768 ppm.
Compound 2Ba was prepared similarly as 2Aa from mesi-
tyltellurium trichloride (0.35 g, 1.0 mmol) and 2-acetylpyrrole
(0.11 g, 1.0 mmol) as colorless crystals. Yield: 0.36 g (85%). M.p.:
153 ꢀC dec. Anal. Calc. for C15H17ONTeCl2 (425.81): C, 42.31; H, 4.02;
N, 3.29. Found: C, 42.27; H, 4.14; N, 3.37. 1H NMR:
d 2.33 (s, 3H, p-
Me), 2.78, 2.82 (2 s, 6H, o-Me), 5.45 (s, 2H, CH2), 6.38 (s, 1H, pyrrole
ring), 6.99 (s, 1H, m-H mesityl ring), 7.06 (s, 1H, m-H mesityl ring),