Isolation and structural characterization of some aryltellurium halides and their hydrolyzed products stabilized by an intramolecular Te...N interaction

Article abstract of DOI:10.1021/om1009022

The isolation of pure [2-(phenylazo)phenyl-C,N′]tellurium(IV) tribromide (6) has been achieved by modifying the reported procedure, which involved transmetalation of [2-(phenylazo)phenyl-C,N′]mercury(II) chloride (7) with TeBr₄. The mixed-valent derivative bis[2-(phenylazo)phenyl- C,N′]ditellurium dichloride (19), incorporating both a divalent and a tetravalent tellurium, was obtained serendipitously during the reduction of [2-(phenylazo)phenyl-C,N′]tellurium(IV) trichloride (16) with hydrazine hydrate. Bis[2-(phenylazo)phenyl-C,N′]telluride (10) has been synthesized by the ortho-lithiation route. Telluride 10, on treatment with SO ₂Cl₂ and Br₂, underwent oxidative addition to give the expected Te(IV) halogenated products bis[2-(phenylazo)phenyl-C, N′]tellurium(IV) dichloride (13) and bis[2-(phenylazo)phenyl-C,N′] tellurium(IV) dibromide (11), respectively. However, a similar reaction of 10 with I₂ resulted in the formation of an unexpected telluronium cation, iodobis[2-(phenylazo)phenyl-C,N′]telluronium triiodide (14), and [2-(phenylazo)phenyl-C,N′]tellurenenyl(II) iodide (12). Alkaline hydrolysis of 16 under reflux conditions resulted in the formation of monomeric [2-(phenylazo)phenyl-C,N′]tellurinic acid (20) and its sodium salt (21) as a cocrystal. Bis[[2-(phenylazo)phenyl-C,N′]tellurium]oxide (22) was obtained from the hydrolysis of [2-(phenylazo)phenyl-C,N′]tellurium(II) chloride (17). The reaction of 13 with an alkaline solution resulted in the formation of the corresponding bis[2-(phenylazo)phenyl-C,N′]tellurium(IV) oxide (23) and dichlorobis[2-(phenylazo)phenyl-C,N′]tellurium(IV) oxide (24). The identity of all the derivatives was confirmed by multinuclear NMR (¹H, ¹³C, ¹²⁵Te) and FT-IR spectroscopy, elemental analysis, and ESI-MS. The structures for tellurium derivatives 6, 10-14, 17, 19, 20-23, and 23A were also confirmed by X-ray crystallography. Density functional theory (DFT) was utilized for optimizing the geometries of 11, 13, and 14 to examine the possibility of a four-membered intramolecular Te...N interaction.

Full text of DOI:10.1021/om1009022

534 Organometallics 2011, 30, 534–546
DOI: 10.1021/om1009022
Isolation and Structural Characterization of Some Aryltellurium Halides
and Their Hydrolyzed Products Stabilized by an Intramolecular
Te N Interaction
3 3 3
Kriti Srivastava,† Poonam Shah,† Harkesh B. Singh,*,† and Ray J. Butcher‡
†Department of Chemistry, Indian Institute of Technology, Bombay, Mumbai 400076, India, and
‡Department of Chemistry, Howard University, Washington, D.C. 20059, United States
Received September 18, 2010
The isolation of pure [2-(phenylazo)phenyl-C,N0]tellurium(IV) tribromide (6) has been achieved by
modifying the reported procedure, which involved transmetalation of [2-(phenylazo)phenyl-C,
N0]mercury(II) chloride (7) with TeBr4. The mixed-valent derivative bis[2-(phenylazo)phenyl-C,
N0]ditellurium dichloride (19), incorporating both a divalent and a tetravalent tellurium, was obtained
serendipitously during the reduction of [2-(phenylazo)phenyl-C,N0]tellurium(IV) trichloride (16) with
hydrazine hydrate. Bis[2-(phenylazo)phenyl-C,N0]telluride (10) has been synthesized by the ortho-
lithiation route. Telluride 10, on treatment with SO2Cl2 and Br2, underwent oxidative addition to give
the expected Te(IV) halogenated products bis[2-(phenylazo)phenyl-C,N0]tellurium(IV) dichloride (13)
and bis[2-(phenylazo)phenyl-C,N0]tellurium(IV) dibromide (11), respectively. However, a similar reaction
of 10 with I2 resulted in the formation of an unexpected telluronium cation, iodobis[2-(phenylazo)phenyl-
C,N0]telluronium triiodide (14), and [2-(phenylazo)phenyl-C,N0]tellurenenyl(II) iodide (12). Alkaline
hydrolysis of 16 under reflux conditions resulted in the formation of monomeric [2-(phenylazo)phenyl-
C,N0]tellurinic acid (20) and its sodium salt (21) as a cocrystal. Bis[[2-(phenylazo)phenyl-C,N0]tellurium]-
oxide (22) was obtained from the hydrolysis of [2-(phenylazo)phenyl-C,N0]tellurium(II) chloride (17). The
reaction of 13 with an alkaline solution resulted in the formation of the corresponding bis[2-(phenyl-
azo)phenyl-C,N0]tellurium(IV) oxide (23) and dichlorobis[2-(phenylazo)phenyl-C,N0]tellurium(IV) oxide
(24). The identity of all the derivatives was confirmed by multinuclear NMR (1H, 13C, 125Te) and FT-IR
spectroscopy, elemental analysis, and ESI-MS. The structures for tellurium derivatives 6, 10-14, 17, 19,
20-23, and 23A were also confirmed by X-ray crystallography. Density functional theory (DFT) was
utilized for optimizing the geometries of 11, 13, and 14 to examine the possibility of a four-membered
intramolecular Te N interaction.
3 3 3
Introduction
Thavornyutikarn.1e They suggested the formation of partially
hydrolyzed products such as RTe(O)X (X = Cl, Br; R = C6H5,
p-EtOC6H4) upon treatment of the organotellurium trihalides
with water. The studies also proposed the formation of com-
pletely hydrolyzed products RTe(OH)3 and RTe(O)OH or
condensed product (RTeO)2O under alkaline conditions. It
was further concluded that the iodo derivative was difficult to
hydrolyze under normal conditions. During the preparation of
isopropyl hex-1-ynyl telluride an organooxo-telluride, an ionic
cluster formulated as [Li(THF)4][{(i- PrTe)12O16Br4{Li(THF)-
Compounds having tellurium-oxygen covalent linkages
are known as oxotellurides or telluroxanes. These oxotellur-
ides are usually prepared by hydrolyzing the respective halides
such as RTeX3, RTeX, and R2TeX2 (R = C6H5, p-EtOC6H4,
p-MeOC6H4, 2,6-Mes2C6H3; Mes = 2,4,6-Me3C6H2; X = Cl,
Br, I).1 Current interest in these oxotellurides is due to their
use in organic synthesis as oxidizing agents as well as catalysts
and also in some organometallic reactions as oxygen transfer
reagents.2 The first detailed investigation on the hydrolysis
of aryltellurium trihalides was reported by McWhinnie and
Br}4}Br] 2THF, was obtained serendipitously by Giolando and
3
co-workers.3 It was formally claimed to be a condensation
*To whom correspondence should be addressed. E-mail: chhbsia@
chem.iitb.ac.in.
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Gordon and Breach: New York, 1974. (g) Alcock, N. W.; Harrison, W. D.
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r
pubs.acs.org/Organometallics
Published on Web 01/04/2011
2011 American Chemical Society

Article
Organometallics, Vol. 30, No. 3, 2011 535
product of organotellurium trihydroxide. Recently Beckmann
et al. have successfully isolated RTe(O)OH (1) and RTe(O)-
(OH)3 (2) (R = 2,6-Mes2C6H3) as a dimer comprising of an
asymmetric four-membered Te2O2 ring structure with exocy-
clic -OH.1i,j Though there are a few reports on the hydrolysis of
aryltellurium(IV) trihalides, very little has been studied about the
hydrolysis of the corresponding tellurium(II) derivatives.4
organochalcogen species which are otherwise unstable and
oligomeric/polymeric.10 In this regard we have recently
reported the synthesis of the discrete novel heptatellurium
covalent cluster 5 by alkaline hydrolysis of [2-(phenylazo)-
phenyl-C,N0]tellurium(IV) trihalides.11 The cluster was sta-
bilized by both five-membered and rare four-membered
Te N intramolecular interactions. Extending this concept,
3 3 3
we thought of systematically investigating the hydrolysis of
[2-(phenylazo)phenyl-C,N0]tellurium(IV) trichloride, [2-(phe-
nylazo)phenyl-C,N0]tellurium(II) chloride, and bis(2-(phenyl-
azo)phenyl)tellurium(IV) dichloride for the isolation of well-
defined monomeric hydrolyzed products.
The hydrolyzed products of diaryltellurium(IV) dihalides
have been well characterized.1,5 Recently much interest has arisen
in the chemistry of telluroxides of the type R2TeO (R = C6H5,
p-EtOC6H4, p-MeOC6H4) because of their usage in various
fields. For example, Kobayashi et al. have isolated oligotellur-
oxane by the reaction of telluroxides with cationic ditelluro-
xanes.6 The telluroxides have also been successfully used to
isolate macrocyclic multitelluranes by the reaction of cationic
ditelluroxane with sodium phthalate.7 Beckmann and co-workers
have demonstrated that the solutions containing di-tert-
butyltin oxide and di-p-anisyltellurium oxide readily absorbed
gaseous CO2.8 In a recent study it has been found that tell-
uroxides exhibit hydrolysis capacity and can be used as a hydro-
lase mimic.9 The structure of the first telluroxide, diphenyltellur-
oxide (Ph2TeO) (3), was reported in the late 1990s by Alcock and
Harrison.1g The solid-state structure suggested that the two
crystallographically independent units were linked together by
It is worth mentioning that though organotellurium(II/I)
compounds derived from 2-(phenylazo)phenyl have been
reported in the literature by McWhinnie and co-workers,12
there has been no systematic study on the tellurium(IV) deriv-
atives. The study of tellurium(IV) derivatives is restricted to
only one example: [2-(phenylazo)phenyl-C,N0]tellurium(IV)
trichloride.13 In this article we describe (i) the synthesis of
a series of organotellurium(IV) halides, (ii) alkaline hydro-
lysis of RTeCl3, RTeCl, and R2TeCl2 (R = 2-(phenylazo)-
phenyl), and (iii) the existence of a rare four-membered
˚
short secondary Te O interactions (2.55(1) A), giving rise to a
3 3 3
dimeric structure. Later on Naumann et al.5a and Klapotke
€
et al.5b independently reported the crystal structure of (C6F5)2TeO
as the toluene solvate and as the dichloromethane and benzene
solvate, respectively. The solid-state structures for this compound
were also found to be similar to the former structure, with a
Te N intramolecular interaction, which was probed in
3 3 3
depth by single-crystal X-ray diffraction studies and DFT
calculations.
˚
relatively shorter secondary Te O interaction (2.20(1) A).
Results and Discussion
3 3 3
Beckmann et al. have reported the structure of ( p-MeO-
C6H4)2TeO (4), having a polymeric arrangement of Te-O bonds
in a zigzag conformation rather than the usual dimeric form.1h
Synthesis. [2-(Phenylazo)phenyl-C,N0]tellurium(IV) tri-
bromide (6)12d has been used as a precursor for the synthesis
of the heptatellurium cluster.11 The isolation of pure 6 posed
(7) Kobayashi, K.; Izawa, H.; Yamaguchi, K.; Horn, E.; Furukawa,
N. Chem. Commun. 2001, 1428.
(8) Beckmann, J.; Dakternieks, D.; Duthie, A.; Lewcenko, N. A.;
Mitchell, C. Angew. Chem., Int. Ed. 2004, 43, 6683.
(9) Dong, Z.; Li, X.; Liang, K.; Mao, S.; Huang, X.; Yang, B.; Xu, J.;
Liu, J.; Luo, G.; Shen, J. J. Org. Chem. 2007, 72, 606.
(10) (a) Hamor, T. A.; Al-Salim, N.; West, A. A.; McWhinnie, W. R.
J. Organomet. Chem. 1986, 310, C5. (b) Kaur, R.; Singh, H. B.; Butcher,
R. J. Organometallics 1995, 14, 4755. (c) Poleschner, H.; Seppelt, K. Chem.
Eur. J. 2004, 10, 6565. (d) Wismach, C.; du Mont, W.-W.; Jones, P. G.; Ernst,
L.; Papke, U.; Mugesh, G.; Kaim, W.; Wanner, M.; Becker, K. D. Angew.
Chem., Int. Ed. 2004, 43, 3970. (e) Kumar, S.; Kandasamy, K.; Singh, H. B.;
Our group and others have made use of the intramolecular
coordination approach for the stabilization and isolation of
€
Wolmershauser, G.; Butcher, R. J. Organometallics 2004, 23, 4199.
(f) Kulcsar, M.; Silvestru, A.; Silvestru, C.; Drake, J. E.; Macdonald, C. L. B.;
Hursthouse, M. E.; Light, M. E. J. Organomet. Chem. 2005, 690, 3217.
(g) Beckmann, J.; Bolsinger, J.; Duthie, A. Organometallics 2009, 28, 4610.
(11) Srivastava, K.; Sharma, S.; Singh, H. B.; Singh, U. P.; Butcher,
R. J. Chem. Commun. 2010, 46, 1130.
(12) (a) Ahmed, M. A. K.; McWhinnie, W. R.; Hamor, T. A.
J. Organomet. Chem. 1985, 293, 219. (b) Ahmed, M. A. K.; McCarthy,
A. E.; McWhinnie, W. R.; Berry, F. J. J. Chem. Soc., Dalton Trans. 1986,
771. (c) Abid, K. Y.; Al-Salim, N. I.; Greaves, M.; McWhinnie, W. R.; West,
A. A.; Hamor, T. A. J. Chem. Soc., Dalton Trans. 1989, 1697. (d) Majeed,
Z.; McWhinnie, W. R.; Hamor, T. A. J. Organomet. Chem. 1997, 549, 257.
(13) Cobbledick, R. E.; Einstein, F. W. B.; McWhinnie, W. R.; Musa,
F. H. J. Chem. Res., Synop. 1979, 145.
(4) Sadekov, I. D.; Maksimenko, A. A.; Maslakov, A. G.; Minkin,
V. I. J. Organomet. Chem. 1990, 391, 179.
(5) (a) Naumann, D.; Tyrra, W.; Herrmann, R.; Pantenburg, I.;
€
Wickleder, M. S. Z. Anorg. Allg. Chem. 2002, 628, 833. (b) Klapotke,
T. M.; Krumm, B.; Mayer, P.; Piotrowski, H.; Ruscitti, O. P. Z. Naturforsch.
2002, B57, 145.
(6) (a) Kobayashi, K.; Deguchi, N.; Takahashi, O.; Tanaka, K.;
Horn, E.; Kikuchi, O.; Furukawa, N. Angew. Chem., Int. Ed. 1999, 38,
1638. (b) Kobayashi, K.; Tanaka, K.; Izawa, H.; Arai, Y.; Furukawa, N.
Chem. Eur. J. 2001, 7, 4272.

536 Organometallics, Vol. 30, No. 3, 2011
Srivastava et al.
Scheme 1. Synthesis of 6 and 8
The tellurium(II) precursor [2-(phenylazo)phenyl-C,N0]tellu-
renenyl(II) chloride (17)12d was prepared by the reduction of
[2-(phenylazo)phenyl-C,N0]tellurenenyl(IV) trichloride (16)13
with hydrazine hydrate in methanol. The formation of 17 was
confirmed by spectroscopic characterization and X-ray crystal-
lography. The reduction of 16 in ethanol with a slight excess of
hydrazine hydrate gave an appreciable amount of the mixed-
valent chloro derivative 19 along with the expected bis[2-(phe-
nylazo)phenyl-C,N0] ditelluride (18) (Scheme 4).16 The spectro-
scopic characterization suggested that one molecule of hydrazine
is attached to 19.
Reactions of [2-(Phenylazo)phenyl-C,N0]tellurium(IV) Trichlo-
ride, [2-(Phenylazo)phenyl-C,N0]tellurenenyl(II) Chloride, and
Bis[2-(phenylazo)phenyl-C,N0]tellurium(IV) Dichloride with
Aqueous Sodium Hydroxide. Refluxing a suspension of 1613 in
2 M sodium hydroxide resulted in the formation of the novel
hydrolyzed products 20 and 21, which precipitated as a bright
orange cocrystal on cooling (Scheme 5). The filtrate afforded a
small amount of azobenzene, indicating a partial decomposition
of 16. The azobenzene formed in this reaction was characterized
some problems. McWhinnie and co-workers have earlier
attempted the synthesis of 6 by utilizing a transmetalation
reaction between [2-(phenylazo)phenyl-C,N0]mercury(II) chlo-
ride (7)14 and TeBr4 (Scheme 1). However, the authors failed to
isolate the desired tribromide in the pure form.12d Our attempts
to synthesize 6 from the reaction of TeBr4 with [2-(phenylazo)-
phenyl-C,N0]lithium15 (9) (Scheme 2) at -114 °C always led to
the formation of only small amounts of bis[2-(phenylazo)-
phenyl-C,N0] telluride (10) as a red liquid along with bis[2-(phe-
nylazo)phenyl-C,N0]tellurium(IV) dibromide (11) as a black
solid, and no tribromide could be isolated. The desired tribro-
mide 6 could be isolated in good yield and pure form by
modifying the reported procedure.12d In our modification, the
reaction time for the transmetalation reaction was increased by
an additional 2 h and the yellow-brown precipitate so obtained
was washed with methanol to remove the mercury(II) chloride-
dioxane addition product.
The treatment of [2-(phenylazo)phenyl-C,N0]lithium (9)
with TeI217 at -114 °C afforded 10 in 17% yield along with a
small amount of the known [2-(phenylazo)phenyl-C,
N0]tellurenyl iodide (12)12d (Scheme 2). The compounds were
separated by column chromatography. The reaction of 10
with SO2Cl2 in dichloromethane at 0 °C gave bis[2-(phenylazo)-
phenyl-C,N0]tellurium(IV) dichloride (13) in 76% isolated yield.
Similarly, the reaction of 10 with Br2 at 0 °C in ether yielded 11 as
a red solid in 75% isolated yield (Scheme 2). In contrast, when a
solution of 10 in dichloromethane was treated with iodine, it
resulted in the formation of cation 14 and 12 instead of the
expected bis[2-(phenylazo)phenyl-C,N0]tellurium(IV) diiodide
(15) (Scheme 2).
1
by its melting point as well as by its H NMR spectrum. The
treatment of 1712d with 2 M sodium hydroxide solution gave a
black solid which upon analysis was found to be the novel
bis[[2-(phenylazo)phenyl-C,N0]tellurium] oxide (22) (Scheme 5).
The treatment of 13 with 2 M sodium hydroxide solution
under reflux conditions gave bis[2-(phenylazo)phenyl-C,N0] tell-
uroxide (23). General spectroscopic characterization and ele-
mental analysis suggested the presence of an ethanol molecule
along with the desired telluroxide. This was further supported by
an X-ray crystal structure determination (vide infra).
The hydrolysis reaction of 13 with 1 M sodium carbonate
solution under an inert atmosphere gave access to the partially
hydrolyzed product 24 (Scheme 5). The spectroscopic charac-
terization and elemental analysis suggested that 24 was asso-
ciated with one water molecule as a solvent of crystallization.
However, all attempts to obtain a suitable crystal of 24 led to the
formation of the dimeric form of telluroxide 23A having a
benzene molecule as the solvent of crystallization.
125Te NMR Spectra. The 125Te NMR chemical shifts of the
synthesized derivatives are given in Table 1. The 125Te NMR
signal for 10 appeared at 667 ppm, which is shifted relatively
downfield as compared to other related tellurides.19 This can
be attributed to the strong Te N intramolecular interac-
3 3 3
tion (vide infra) in 10. As expected, the signals for 13, 11, and
14 appeared downfield at 835, 781, and 1163 ppm, respec-
tively. The relatively more downfield shift of the 125Te NMR
signal for 14 is due to its cationic nature. The 125Te NMR
signals observed for 19 at 835 and 1224 ppm are in accor-
dance with the literature values for related mixed-valent
compounds.20 The 125Te NMR spectrum for 6 in DMSO-
d6 showed four signals instead of the expected single signal.
This could be due to the formation of DMSO-d6 adducts
with 6.21 The 125Te NMR spectrum for 20 and 21 showed a
single sharp signal at 1611 ppm instead of the expected two.
The probable reason for this anomaly could be the ionization
of the sodium ion of salt 21 and hydrogen ion of the acid 20.
As suggested by Detty et al.,18 the oxidative addition of
iodine to 10 may occur with the formation of an inter-
mediate, a 1:2 complex between the telluride and iodine
which may then dissociate into the telluronium cation
having triiodide as the anion (14) (Scheme 3). However,
the formation of the trace amount of 12 along with 14 can
also take place via the reductive elimination of the in
situ generated diiodide 15 (Scheme 3). The formation of
14 and 12 was unambiguously confirmed by X-ray crystal-
lography.
(14) Roling, P. V.; Kirt, D. D.; Dill, J. L.; Hall, S.; Hollstrom, C.
J. Organomet. Chem. 1976, 116, 39.
(15) Roling, P. V. J. Org. Chem. 1975, 40, 2421.
(16) Ahmed, M. A. K.; McWhinnie, W. R.; Hamor, T. A.
J. Organomet. Chem. 1985, 281, 205.
(17) Brauer, G. Handbook of Preparative Inorganic Chemistry, 3rd
ed.; Academic Press: New York, 1975.
(18) (a) Detty, M. R.; Friedman, A. E.; McMillan, M. Organometal-
lics 1995, 14, 1442. (b) Detty, M. R.; Williams, A. J.; Hewitt, J. M.;
McMillan, M. Organometallics 1995, 14, 5258. (c) Kumar, S.; Helt, J.-C.
P.; Autschbach, J.; Detty, M. R. Organometallics 2009, 28, 3426.
(19) (a) Minkin, V. I.; Sadekov, I. D.; Maksimenko, A. A.; Kompan,
O. E.; Struchkov, Y. T. J. Organomet. Chem. 1991, 402, 331and
references therein. (b) Apte, S. D.; Singh, H. B.; Butcher, R. J. J. Chem.
Res., Synop. 2000, 160; J. Chem. Res., Miniprint 2000, 559.
(20) Beckmann, J.; Hesse, M.; Poleschner, H.; Seppelt, K. Angew.
Chem., Int. Ed. 2007, 46, 8277.
(21) Menon, S. C.; Singh, H. B.; Patel, R. P.; Das, K.; Butcher, R. J.
Organometallics 1997, 16, 563.

Article
Organometallics, Vol. 30, No. 3, 2011 537
Scheme 2. Synthesis of 10, 11, 13, and 14
Scheme 3. Mechanism for the Formation of 12 and 14
Scheme 4. Synthesis of 18 and 19
Te N distance among all the compounds reported in the
3 3 3
This would result in the presence of tellurate ion as the only
tellurium-containing species in the solution, thus leading to
only one signal. As observed by others, the 125Te NMR
chemical shifts for the dihalotellurium(IV) derivatives ap-
pear at lower field than for the corresponding telluride.22
The 125Te NMR signal for 22 appeared at 1535 ppm. The
relatively higher value of the 125Te NMR chemical shift for
22 could be due to the presence of the shortest intramolecular
present study. The 125Te signals for compound 23 and 24
appeared at 1228 and 1243 ppm, respectively. The higher
value for these Te(IV) oxo derivatives as compared to those
for 13, 11, and 14 is due to the higher electronegativity of the
oxygen atom.
Crystal Structures. The molecular structure of 6 is shown
in Figure 1; crystallographic data are given in Table 2.
The geometry around tellurium in 6 can be described as
pseudo trigonal bipyramidal with C1, Br3, and the lone
pair lying in the basal plane. The torsion angle of 2.32° for
C1-N1-Te-Br3 suggests a nearly planar arrangement
for these four atoms. The atoms Br1 and Br2 occupy
the axial positions with a Br1-Te-Br2 bond angle of
171.04(4)°. The twist angle between the two phenyl rings
of the 2-(phenylazo)phenyl moiety is 4.97°. The intramo-
€
(22) (a) Klapotke, T. M.; Krumm, B.; Mayer, P.; Polborn, K.;
€
Ruscitti, O. P. Inorg. Chem. 2001, 40, 5169. (b) Klapotke, T. M.; Krumm,
B.; Mayer, P.; Piotrowski, H.; Ruscitti, O. P. Z. Anorg. Allg. Chem. 2002,
628, 229. (c) Beckmann, J.; Dakternieks, D.; Duthie, A.; Smith, N. A.
J. Organomet. Chem. 2003, 669, 149. (d) Kandasamy, K.; Kumar, S.; Singh,
€
H. B.; Wolmershauser, G. Organometallics 2003, 22, 5069. (e) Chauhan,
A. K. S.; Anamika; Kumar, A.; Srivastava, R. C.; Butcher, R. J.; Duthie, A.
J. Organomet. Chem. 2006, 691, 5887. (f) Amosova, S. V.; Martynov, A. V.;
Shagun, V. A.; Musalov, M. V.; Larina, L. I.; Krivdin, L. B.; Zhilitskaya, L. V.;
Voronkov, M. G. J. Organomet. Chem. 2008, 693, 2509.
˚
lecular Te N distance (2.483(14) A) is longer than that
3 3 3
reported for the related [2-(2-pyridyl)phenyl]tellurium(IV)

538 Organometallics, Vol. 30, No. 3, 2011
Srivastava et al.
Scheme 5. Synthesis of 20-24
Table 1. 125Te NMR Chemical Shifts for the Synthesized
Tellurium Derivatives
entry
125Tea (ppm)
10b
667
835
781
1163
13b
11b
14c
19b
6c
836, 1224
1330, 1317, 1306, 1277
1611
1535
1228
1243
20-21d
22b
23b
24b
a Me2Te has been used as the reference. b In CDCl3. c In DMSO-d6.
d In CD3OD.
tribromide (2.244(14) A),23 [o-((((1S,2R)-2-hydroxy-2-phenyl-1-
˚
Figure 1. Molecular structure of 6 at the 50% probability level
˚
(H atoms are omitted for clarity). Selected bond lengths (A),
methylethyl)amino)methinyl)phenyl]tellurium(IV) tribromide
21
(2.289(6) A), and [2-(phenylazo)phenyl-C,N0]tellurium(IV)
˚
bond angles (deg), and torsion angles (deg): Te-C1 2.131(8), Te
13
trichloride (2.414 A). However, it is shorter than the sum
˚
3 3 3
N1 = 2.483(14), Te-Br1 = 2.628(9), Te-Br2 = 2.651(10), Te-
Br3 = 2.524(13); C1-Te-N1 = 70.0(3), C1-Te-Br1 = 86.9(2),
C1-Te-Br2 = 86.0(2), C1-Te-Br3 = 98.5(2), N1-Te-Br3 =
168.5(3).
of the van der Waals radii24 for tellurium (2.06 A) and nitrogen
˚
˚
(1.55 A). The N1 Te-Br3 angle, 168.5(3)°, is close to that
3 3 3
reported for other related derivatives.21,25 The molecule shows
the presence of intermolecular C-H Br interactions: C4-
3 3 3
˚
H4A Br1# at 2.95(5) A with a bond angle of 156.01(71)°,
˚
3 3 3
and C11-H11A Br2# at 2.82(6) A with a bond angle of
3 3 3
˚
C8-H8A Br2# at 2.86(4) A with a bond angle of 145.03(84)°,
3 3 3
163.82(77)°.
The geometry around the tellurium atom in 10 is T-shaped
(Figure 2). The planes containing each of the 2-(phenyl-
azo)phenyl units make an angle of 66.80° with each other.
The C1A-Te-C1B angle in 10 is 95.02(6)° and is close to that
(23) Al-Salim, N.; West, A. A.; McWhinnie, W. R.; Hamor, T. A.
J. Chem. Soc., Dalton Trans. 1988, 2363.
(24) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(25) Chao, G. Y.; McCullough, J. D. Acta Crystallogr. 1962, 15, 887.

Article
Organometallics, Vol. 30, No. 3, 2011 539
Table 2. Crystallographic Data of 6, 10, 11, and 12
6
10
11
12
empirical formula
fw
cryst syst
C12H9Br3N2Te
548.54
triclinic
P1
8.9195(4)
9.7340(5)
10.4956(4)
113.570(4)
93.713(3)
111.227(4)
754.78(6)
2
2.414
295(2)
1.541 84
4.74-77.45
24.730
C24H18N4Te
490.02
C24H18Br2N4Te
649.84
triclinic
P1
8.9613(2)
13.7629(4)
20.4098(6)
78.860(2)
88.143(2)
72.840(2)
2359.03(11)
4
1.830
200(2)
0.710 73
4.64-32.55
4.667
C12H9IN2Te
435.71
monoclinic
P21/c
9.2451(6)
12.6258(10)
10.7974(8)
90
99.882(4)
90
monoclinic
P121/n1
6.53650(10)
14.2249(3)
21.7793(4)
90
91.7370(17)
90
2024.13(6)
4
1.608
space group
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z
1241.65(16)
4
2.331
D(calcd) (Mg/m3)
temp (K)
200(2)
100(2)
˚
λ (A)
0.710 73
4.59-34.75
1.487
0.710 73
3.13-35.05
4.856
range of θ (deg)
abs coeff (mm-1
)
no. of obsd rflns (I > 2σ)
final R(F) (I > 2σ(I))
3144
0.0658
0.1984
3144/48/159
1.073
8223
0.0295
0.0631
8223/0/262
1.033
14411
0.0427
0.0738
14 411/34/554
1.070
5446
0.0214
0.0457
5446/0/145
1.031
Rw(F2) indices (I > 2σ)
no. of data/restraints/params
goodness of fit on F2
Figure 3. Molecular structure of 12 at the 50% probability level
(H atoms are omitted for clarity).
and 17 is identical with that of telluride 10. Compounds 12 and
17 show the presence of a five-membered intramolecular Te
˚
N2 interaction with bond lengths of 2.210(14) and 2.218(19) A,
3 3 3
Figure 2. Molecular structure of 10 at the 50% probability level
˚
(H atoms are omitted for clarity). Selected bond lengths (A), bond
respectively. Notably, the Te N2 bond length in 12 is shorter
˚
angles (deg), and torsion angles (deg): Te-C1A = 2.097(16),
3 3 3
(0.42 A) than that of the structure reported earlier, whereas for
17 it is almost the same.12d The Te-I bond length of 2.924(2) A
Te-C1B = 2.162(15), N2A Te = 2.617(2); C1A-Te-C1B =
3 3 3
˚
95.02(6), N2A Te-C1B = 162.24(5).
3 3 3
˚
is also longer by 0.47 A in comparison with the reported struc-
of previously reported related structures such as bis[2-(((40-
methoxyphenyl)imino)methinyl)phenyl] telluride (96.3°),19a
bis(2-((isopropylimino)methinyl)phenyl) telluride (93.5(7)°),19a
and bis[2-(4,4-dimethyl-2-oxazolinyl)phenyl] telluride (94.2°).19b
ture; however, no such difference in Te-Cl bond length was
observed for 17.12d Interestingly, the molecular structure for 12
˚
shows an intermolecular Te N (3.345 A) interaction with an
3 3 3
N1 Te#-C1# bond angle of 160.22° that can be extended in
3 3 3
˚
The intramolecular Te N2A distance of 2.62(2) A is shorter
3 3 3
the c direction (see Figure S1 in the Supporting Information).
The geometries around the tellurium atoms in 13 and 11 are
pseudo trigonal bipyramidal (Figures 5 and 6). The asymmetric
unit of 11 contains two molecules (A and B) that have almost
identical structural parameters except for a significant difference
than those reported for related bis[2-(((40-methoxyphenyl)-
imino)methinyl)phenyl] telluride (2.70 A),19a bis(2-((isopropyl-
˚
19a
˚
imino)methinyl)phenyl) telluride (2.72 A),
and bis[2-(4,4-
19b
dimethyl-2-oxazolinyl)phenyl] telluride (2.95 A). The bond
˚
angle N2A Te-C1B deviates from linearity and has a value
3 3 3
in one of the bond angles, N1C Te2-C1D (∼8°), as com-
3 3 3
of 162.24(5)°. These Te-C distances are, however, in close
agreement with the sum of the single-bonded covalent radii for
pared to the other N Te-C bond angle. The Te-Cl bonds in
3 3 3
˚
˚
13 (Te-Cl1 = 2.53(12) A; Te-Cl2 = 2.49(11) A) are in accor-
dance with related reported structures such as (4-methoxy-
26
˚
Te-C (2.11 A) bond, as suggested by Pauling.
The molecular structures of 12 and 17, as shown in Figures 3
and 4, represent new polymorphic forms of previously reported
structures.12d The geometry around the tellurium atom in 12
phenyl)[2-((4-nitrobenzylidene)amino)-5-methylphenyl]tellu-
27
˚
˚
rium dichloride (Te-Cl1 = 2.51(1) A; Te-Cl2 = 2.47(1) A),
(27) Chauhan, A. K. S.; Anamika; Kumar, A.; Srivastava, R. C.;
Butcher, R. J.; Beckmann, J.; Duthie, A. J. Organomet. Chem. 2005, 690,
1350.
(26) Pauling, L. The Nature of the Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1960.

540 Organometallics, Vol. 30, No. 3, 2011
Srivastava et al.
the related structures.22a,31a,31b The molecular structure of 13
shows disorder in one of the azobenzene units with respect to the
position of the nitrogen atoms. This leads to the simultane-
ous presence of both five-membered and rare four-membered
intramolecular Te N interactions30 (vide infra) in 13.
3 3 3
The angle between the planes containing two azobenzene
units in 13 is 31.01°, suggesting the greater planarity of the azo-
benzene units in 13 as compared to those in 10, where the value
was 66.80°. The crystal geometry of 13 shows the presence
of intermolecular H Cl interactions, with the H9BA Cl1
3 3 3
3 3 3
˚
and H3BA Cl1 distances being 2.80(1) and 2.89(1) A, respec-
3 3 3
tively. The corresponding C9B-H9BA Cl1 and C3B-
3 3 3
H3BA Cl1 bond angles are 148.39(3)° and 154.01(31)° re-
3 3 3
spectively. The presence of an intermolecular H Cl interaction
3 3 3
leads the molecules in 13 to adopt a spiral-shaped structure (see
Figure S2 in the Supporting Information). The crystal struc-
ture of compound 11 also shows the presence of an intermolec-
ular H Br interaction with an H5AA Br1A distance of
Figure 4. Molecular structure of 17 at the 50% probability level
(H atoms are omitted for clarity).
3 3 3
3 3 3
˚
3.03(3) A and C5A-H5AA Br1A bond angle of 151.05(34)°.
3 3 3
The asymmetric unit of 14 contains two molecules, where
molecule Ahas only a five-membered intramolecular interaction
while molecule B exhibits both four- and five-membered intra-
molecular nonbonded Te N interactions (Figure 7). The
3 3 3
geometry around the tellurium atom in 14 is distorted tetrahe-
dral. In 14, the intramolecular Te N distances are much
shorter than those observed in 11 and 13, which can be attrib-
3 3 3
uted to the cationic nature of 14. The Te-I bond length of
2.78(12) A in 14 is very close to that reported for the iodo-
˚
[2-((dimethylamino)methyl)phenyl]phenyltelluronium iodide
18b
˚
(2.82 A). Also, the Te-I distance in 14 is slightly shorter
˚
(∼0.14 A) than those reported for diphenyltellurium(IV)
diiodide,32 bis(4-methoxyphenyl)tellurium(IV) diiodide,33 bis-
(naphthyl)tellurium(IV) diiodide,34 and bis(4-chlorophenyl)-
tellurium(IV) diiodide.25a The packing diagram (see Figure S3
in the Supporting Information) shows that separated I3- anions
-
balance the charge of the telluronium cation via a Te I3
3 3 3
-
secondary bonding interaction. The other end of I3 interacts
with an iodine of an adjacent tellurium iodide molecule and
propagates in one direction.
Figure 5. Molecular structure of 13 at the 50% probability level
˚
(H atoms are omitted for clarity). Selected bond lengths (A),
bond angles (deg), and torsion angles (deg): Te-C1A = 2.131(4),
The molecular geometries for 20 and 21 are shown in
Figures 8 and 9. The molecule crystallizes in a chiral space
group. The chirality in 20 and 21 is probably due to the nearly
perpendicular orientation of the “TeO2” framework with
respect to the planar 2-(phenylazo)phenyl group bonded to
it. The structure shows crystallization of the sodium salt of
the monomeric tellurinic acid [Naþ{RTe(O)O}] (21) with the
parent acid {RTe(O)OH}(20) (R = 2-(phenylazo)phenyl).35
Te-C1B = 2.139(4), N1A Te = 2.841(4), N2B Te =
3 3 3 3 3 3
2.770(4), Te-Cl1 = 2.528(12), Te-Cl2 = 2.494(11); C1A-Te-
C1B = 98.65(17), Cl1-Te-Cl2 = 171.43(5), N1A Te-C1B =
3 3 3
146.63(16), N2B Te-C1A = 158.34(14).
3 3 3
(4-ethoxyphenyl)[2-(benzylideneamino)-5-methylphenyl]tellu-
28
˚
˚
rium dichloride (Te-Cl1 = 2.54(9) A; Te-Cl2 = 2.49(9) A),
cis-3,5-bis(chloromethyl)-1,4-oxatellurane(IV) 4,4-dichloride
(Te-Cl1=2.50(3) A; Te-Cl2=2.49(3) A),29 and bis(p-methyl-
˚
˚
˚
phenyl)tellurium(IV) dichloride (Te-Cl1 = 2.49(2) A; Te-
(32) Alcock, N. W.; Harrison, W. D. J. Chem. Soc., Dalton Trans.
1984, 869.
(33) Farran, J.; Alvarez-Larena, A.; Capparelli, M. V.; Piniella, J. F.;
Germain, G.; Torres-Castellanos, L. Acta Crystallogr. 1998, C54, 995.
(34) Lang, E. S.; Fernandes, R. M., Jr; Silveira, E. T.; Abram, U.;
Cl2 = 2.54(2) A).22c Similarly in molecule 11 the bond lengths
˚
˚
˚
Te1-Br1A = 2.69(6) A and Te1-Br2A = 2.66(6) A and Br1-
Te1-Br2 bond angle (172.86(2)°) are close to those reported for
ꢀ
ꢀ
Vazquez-Lopez, E. M. Z. Anorg. Allg. Chem. 1999, 625, 1401.
(28) Wu, Y.; Ding, K.; Wang, Y.; Zhu, Y.; Yang, L. J. Organomet.
Chem. 1994, 468, 13.
(29) Laitalainen, T.; Sundberg, M. R.; Uggla, R.; Bergman, J. Poly-
(35) Thisstoichiometrywasinitiallyestablishedbyrefiningtheoccupancy
of this partial Na (Na1) and restraining the thermal parameters of the two Na
atoms (Na1 and Na2) to be similar. As the occupancy of Na1 was refined to a
value very close to 0.50, it was fixed at this value for future calculations, as
otherwise the occupancy and thermal parameters of this atom are highly
correlated. Around Na1 there are disordered water molecules which fill the
vacancy when this position is not occupied by the sodium cation and the
species is in the acid form. In the tellurinic acid anion the two O atoms are
disordered with occupancies of 0.569(4) and 0.431(4), while in the tellurinic
acid/salt cocrystal one of the O positions is fully occupied and the other is
disordered over two positions (O-H and O for the acid and salt anion,
respectively), each with 50% occupancy. The proton attached to O2AA was
found in the difference Fourier at an appropriate O-H distance and
Te-O-H angle and had a normal hydrogen bond to O2WA.
hedron 1997, 16, 2441.
(30) (a) Niyomura, O.; Kato, S.; Inagaki, S. J. Am. Chem. Soc. 2000,
122, 2132. (b) Chauhan, A. K. S.; Kumar, A.; Srivastava, R. C.; Butcher, R. J.
J. Organomet. Chem. 2002, 658, 169. (c) Chauhan, A. K. S.; Singh, P.;
Kumar, A.; Srivastava, R. C.; Butcher, R. J.; Duthie, A. Organometallics
2007, 26, 1955. (d) Chauhan, A. K. S.; Singh, P.; Srivastava, R. C.; Duthie,
A.; Voda, A. Dalton Trans. 2008, 4023.
(31) (a) Chauhan, A. K. S.; Kumar, A.; Srivastava, R. C.; Beckmann,
J.; Duthie, A.; Butcher, R. J. J. Organomet. Chem. 2004, 689, 345.
(b) Bakshi, P. K.; Cameron, T. S.; Ali, M. E. S.; Malik, M. A.; Smith, B. C.
Inorg. Chim. Acta 1993, 204, 27.

Article
Organometallics, Vol. 30, No. 3, 2011 541
˚
Figure 6. Molecular structure of 11 at the 50% probability level (H atoms are omitted for clarity). Selected bond lengths (A), bond
angles (deg), and torsion angles (deg): Te1-C1A = 2.148(5), Te1-C1B = 2.150(5), N2A Te1 = 2.864(4), N2B Te1 = 2.776(5),
3 3 3 3 3 3
Te1-Br1A = 2.694(6), Te1-Br2A = 2.659(6), Te2-C1C = 2.089(11), Te2-C1D = 2.137(5), N2D Te2 = 2.754(4), N1C Te2 =
3 3 3 3 3 3
2.871(6), Te2-Br1B = 2.682(6), Te2-Br2B = 2.662(7); C1A-Te1-C1B = 96.0(2), Br1A-Te1-Br2A = 172.86(2), N2A Te1-C1B =
3 3 3
147.89(17), N2B Te1-C1A = 155.12(17), C1C-Te2-C1D = 96.6(4), Br1B-Te2-Br2B = 172.03(3), N2D Te2-C1C = 156.6(3),
3 3 3 3 3 3
N1C Te2-C1D = 140.33(19).
3 3 3
˚
Figure 7. Molecular structure of 14 at the 50% probability level (H atoms are omitted for clarity). Selected bond lengths (A), bond
angles (deg), and torsion angles (deg): Te1-C1A = 2.144(14), Te1-C13A = 2.121(14), N2A Te1 = 2.481(11), N4A Te1 = 2.756(13),
3 3 3
3 3 3
Te1-I1 = 2.782(12), Te2-C1B = 2.160(16), Te2-C13B = 2.143(16), Te2-N2B = 2.476(13), N3BB Te2 = 2.796(28), Te2-I2 =
3 3 3
2.778(15), I11-I12 = 2.953(16), I12-I13 = 2.875(16), I21-I22 = 2.932(14), I22-I23 = 2.905(14); I13-I12-I11 = 179.30(6),
I23-I22-I21 = 175.88(5), C13A-Te1-C1A = 97.4(5), N2A-Te1-I1 = 162.3(3), C13B-Te2-C1B = 95.5(6), N2B-Te2-I2 =
162.7(3), N3BB-Te2-C1B = 148.83(67).
In the asymmetric unit there are two Te centers. One is fully
occupied with the sodium salt 21 of the parent tellurinic acid
20 (Figure 8), while the other portion is 50% occupied by the
salt and 50% occupied by the parent tellurinic acid 20
(Figure 9). Thus, the overall percentage of the acid is 25%.
The two units are held together by strong multiple hydrogen
bonding interactions through a ladder-type Naþ and water
structure and also to isolated water molecules in the lattice
(see Figures S4 and S5 in the Supporting Information). The
superimposition of Figures 8 and 9 is given in the Supporting
Information (Figure S6).
indicating a stronger interaction. Each oxygen of the anion and
acid is involved in multiple strong hydrogen bonding interac-
tions, thus preventing it from interacting with another tellurium
atom to dimerize.1i In structures 20 and 21 the 2-(phenylazo)-
phenyl nitrogen occupies the position taken by the bridging
oxygen of the dimeric structure,1i thus preventing dimerization.
˚
The Te-O bond lengths range between 1.84 and 1.88 A
and are the shortest observed for any organotellurium oxide.
These bonds are also shorter thanthe sum of the covalent radii
˚
for Te and O (2.15 A). A comparison table for the Te-O bond
lengths of 20 and 21 with those of other related structures
is given in the Supporting Information (Table S1), as is a
diagrammatic representation of the number of compounds
Considering only the primary bonds and the lone pair, the
geometry around tellurium can be best described as distorted
tetrahedral. The intramolecular Te N distances 2.694(3) and
˚
containing Te-O distances in the range of 1.832-3.144 A
(Figure S7). The acid proton is involved in hydrogen bonding
with the water molecules.
3 3 3
˚
2.708(3) A in both units are less than the sum of the van der
˚
Waals radii24 for tellurium and nitrogen (Te, 2.06 A; N, 1.55 A),
˚

542 Organometallics, Vol. 30, No. 3, 2011
Srivastava et al.
Figure 8. Molecular structure showing the presence of a sodium salt (21) of tellurinic acid at the 50% probability level. Selected bond
˚
lengths (A) and bond angles (deg): Te1-O1A = 1.876(2), Te1-O2AB = 1.846(14), Te1-C1A = 2.142(4), Te1 N2A = 2.694(3),
3 3 3
Te2-O1BA = 1.885(14), Te2-O2BA = 1.870(14), Te2-C1B = 2.144(4), Te2 N2B = 2.708(3); O2AB-Te1-O1A = 100.1(16),
O1BA-Te2-O2BA = 109.3(19), N2A Te1-O1A = 162.2(11), N2B Te2-O1BA = 162.0(13).
3 3 3 3 3 3
3 3 3
Figure 9. Molecular structure showing the presence of tellurinic acid (20) and its sodium salt (21) at the 50% probability level. Selected
˚
bond lengths (A): Te1-O2AA = 1.842(14), O2AA-H2C = 0.840.
There is an interesting Na(H2O)n water cluster in the
structure. When both sodium atoms are present in full
occupancy (i.e., when only the salt is present), this forms a
ladderlike structure containing six-coordinate Na with both
terminal water and triply bridging water molecules (see
Figure S4 in the Supporting Information). The triply bridg-
ing oxygens are formally five-coordinate; therefore, the
bonding must be more electrostatic in nature. This type of
triply bridging water cluster has been previously observed for
sodium and other alkali metals (CSD).36 In the acid form, the
sodium atoms in the water cluster are still six-coordinate
with terminal and singly bridging water molecules (see
Figure S5 in the Supporting Information). In addition to
the water molecules in the Na(H2O)n cluster, there are water
molecules in the lattice. All water molecules are involved in
hydrogen bonds to each other and the oxygen atoms from
the tellurinic acid/anion. Thus, the structure is stabilized by
an extensive set of relatively strong hydrogen bonds.
The geometry around the tellurium atom in 22 is T-shaped
(36) (a) Kennedy, A. R.; Andrikopoulos, P. C.; Arlin, J.-B.;
Armstrong, D. R.; Duxbury, N.; Graham, D. V.; Kirkhouse, J. B. A. Chem.
Eur. J. 2009, 15, 9494. (b) Rozantsev, G. M.; Radio, S. V.; Gumerova, N. I.;
Baumer, V. N.; Shishkin, O. B. J. Struct. Chem. 2009, 50, 296. (c) Shen, L.;
Xu, Y.-Q.; Gao, Y.-Z.; Cui, F.-Y.; Hu, C.-W. J. Mol. Struct. 2009, 934, 37.
with an N Te-O bond angle of 163.85(13)°. The geometry
3 3 3
around oxygen is V-shaped (Figure 10; crystallographic data
are given in Table 3) with a Te1-O-Te2 bond angle of
122.95(15)°. The geometry around oxygen is similar to that

Article
Organometallics, Vol. 30, No. 3, 2011 543
˚
The secondary intermolecular Te O distance (2.62(12) A)
in 23 is close to that observed for the previously reported
3 3 3
˚
Ph2TeO (2.54 A) but is longer than that observed for
˚
(C6F5)2TeO (2.20 A). The intramolecular Te N interac-
3 3 3
tion present in 23 does not prevent dimerization; however, it
slightly lengthens the intermolecular Te O interaction.
3 3 3
The distance is well within the sum of the van der Waals
24
radii24 for tellurium and oxygen (Te, 2.06 A; O, 1.52 A).
˚
˚
˚
The Te N2A intramolecular distance (2.714(1) A) is longer
3 3 3
as compared with that in 10. The N2A Te-O angle is
3 3 3
163.63(5)°.
The molecular geometry of 23A is shown in Figure 12. The
geometry around the tellurium atom is similar to that for the
dimer of 23. The crystal structure of 23A shows benzene as
the solvent of crystallization. The Te-O bond length in 23A
˚
is 1.876(6) A, which is slightly longer than that observed for
˚
23 (1.864(12) A). The secondary intermolecular Te
O
3 3 3
˚
˚
distance in 23A is 2.434(6) A, shorter by 0.189 A than that
in 23. Thus, the structure of 23A resembles more those of
Ph2TeO1g and (C6F5)2TeO5 than that of 23. The intramolec-
Figure 10. Molecular structure of 22 at the 50% probability level
˚
(H atoms are omitted for clarity). Selected bond lengths (A), bond
angles (deg), and torsion angles (deg): Te1-O1 = 2.026(3), Te2-
O1 = 2.007(3), Te1-C1A = 2.065(4), Te2-C1B = 2.073(4),
˚
ular Te N distance in 23A is 2.813(7) A, and the
3 3 3
N2B Te-O bond angle is 160.5(2)°.
3 3 3
Computational Study: On the Existence of a Four-Membered
Intramolecular Te N Interaction. Crystal structures ob-
Te1 N2A=2.363(3), Te2-N2B=2.385(3); O1-Te1-C1A=
3 3 3
3 3 3
92.22(14), O1-Te1-N2A = 163.85(13), O1-Te2-N2B =
163.66(12), Te2-O1-Te1 = 122.95(15).
tained for the halo derivatives (11, 13, and 14) suggested
the presence of both normal five-membered and unusual
four-membered intramolecular Te N interactions. In or-
reported for selenenic acid anhydride bis[(8-(dimethyl-
amino)-1-naphthyl)selenium] oxide;37 however, the Te1-O-
Te2 angle is larger than the Se-O-Se angle (117.0(3)°). This
obtuse bond angle is closer to that reported for (μ-oxo)bis-
[diphenyltrifluoroacetoxytellurium] hydrate (124.9°).38 The
3 3 3
der to get a clear picture of the existence of these interactions,
density functional theory calculations (DFT) were per-
formed. The parameters obtained from optimized structures
of the molecules were in conformity with the crystal struc-
tures. The optimized geometries41 for 11 and 13-15 showed
˚
Te-O bond lengths (Te1-O1 = 2.026(3) A and Te2-O1 =
the presence of normal five-membered Te N intramolec-
˚
2.007(3) A, respectively) are much closer to those reported
3 3 3
ular interactions. However, the optimized geometries of the
halo derivatives 11 and 13-15 showed the presence of a four-
for tetra-p-anisylditelluroxane bis(pyridylcarboxylates) (2.001,
2.015 A),39 than those reported for polymeric diorganotellur-
˚
membered Te N intramolecular interaction as well. To
3 3 3
˚
oxane (2.100, 2.025 A) or other related oxotellurium deriva-
tive.40 The Te1 N2A and Te2 N2B intramolecular dis-
quantify the secondary bonding five-membered Te
N
3 3 3
3 3 3
3 3 3
interactions as well as to substantiate the presence of four-
membered interactions, second-order perturbation energies
(ETe N) were calculated for the optimized geometries of the
˚
tances of 2.363(3) and 2.385(3) A are much shorter as compared
to those of other oxo derivatives reported in this paper (vide
supra). The N Te-O bond angle in 22 is 163.85(13)°. The
3 3 3
3 3 3
compounds.42 The values for Te N interaction energy
intramolecular Te N interaction is longer by approximately
˚
3 3 3
3 3 3
(ETe N) obtained from NBO analyses indicated the coex-
istence of both types of interactions in 11, 13, and 14.
0.15 A and the N Te-O bond angle is greater by 2° as
compared to those of the precursor 17.
3 3 3
3 3 3
Surprisingly, the strength of the Te N interaction in-
3 3 3
The geometry around the tellurium atom in 23 is distorted
trigonal bipyramidal with O, O#, and C1B occupying the
equatorial sites, whereas C1A and the lone pair are in the axial
positions. Due to the presence of a secondary intermolecular
creases from the chloro to the iodo derivative (Table 4).
To confirm the presence of the four-membered Te
N
3 3 3
interaction, bond critical points (bcp) were calculated using
the AIM2000 program.43 The bond critical point observed
between Te and N for both types of interactions confirmed
the presence of four-membered interactions (see Figure S70
in the Supporting Information). The electron densities (F) are
Te O interaction, the molecule has a dimeric structure
3 3 3
similar to that reported for Ph2TeO1g and (C6F5)2TeO.5 The
geometry around the tellurium atom in the dimer is distorted
octahedral, with O, O#, N2A, and C1B occupying the equator-
ial sites, whereas C1A and the lone pair are in the axial positions
(Figure 11). The molecule shows the presence of ethanol as a
solvent of crystallization.
greater for five-membered Te N interactions as compared
3 3 3
to those for four-membered interactions. The values of the
2
Laplacian (r (Fr)) as well as total energy densities (H)
obtained at the bond critical points (Table 5) of Te
N
3 3 3
(37) Fujihara, H.; Tanaka, H.; Furukawa, N. J. Chem. Soc., Perkin
Trans. 2 1995, 2375.
(38) Alcock, N. W.; Harrison, W. D.; Howes, C. J. Chem. Soc.,
(41) Geometry optimization were performed at the B3LYP/6-
311G(d,p) level for H, C, N, O and at the Lanl2dz(d,p) level for Te
using the Gaussian 03 software package. (see the Supporting Informa-
tion for details): Frisch, M. J. et al. Gaussian 03, revision C.02; Gaussian,
Inc., Wallingford, CT, 2004.
(42) (a) Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. Rev. 1988, 88,
899. (b) Glendening, E. D.; Reed, A. E.; Carpenter, J. E.; Weinhold, F. NBO
Version 3.1.
Dalton Trans. 1984, 1709.
(39) Chandrasekhar, V.; Kumar, A. J. Organomet. Chem. 2009, 694, 2628.
(40) (a) Mancinelli, C. S.; Titus, D. D.; Ziolo, R. F. J. Organomet.
Chem. 1977, 140, 113. (b) Magnus, P.; Roe, M. B.; Lynch, V.; Hulme, C.
J. Chem. Soc., Chem. Commun. 1995, 1609. (c) Beckmann, J.; Dakternieks,
D.; Duthie, A.; Lewcenko, N. A.; Mitchell, C.; Sch€urmann, M. Z. Anorg.
€
Allg. Chem. 2005, 631, 1856. (d) Klapotke, T. M.; Krumm, B.; Mayer, P.;
(43) Bader, R. F. W. Atoms in Molecules: A Quantum Theory; Oxford
University Press: New York, 1990.
Polborn, K.; Schwab, I. Z. Anorg. Allg. Chem. 2005, 631, 2677.

544 Organometallics, Vol. 30, No. 3, 2011
Table 3. Crystallographic Data of 13, 14, 17, and 20-21
Srivastava et al.
13
14
17
20-21
empirical formula
fw
cryst syst
C
24H18Cl2N4Te
C24H18I4N4Te
997.62
triclinic
P1
8.468
8.927
19.089
102.77
96.82
C12H9ClN2Te
344.26
monoclinic
C2/c
31.3486(10)
4.09590(10)
20.1937(7)
90
116.074(2)
90
C48H87N8Na3O33Te4
1883.63
orthorhombic
Pca21
18.0833(6)
5.0482(3)
38.0518(13)
90
90
90
3473.7(3)
2
1.801
560.92
orthorhombic
Pbcn
29.6142(9)
12.8389(3)
12.4737(2)
90
90
90
4742.7(2)
8
1.571
space group
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
95.65
3
˚
V (A )
Z
1385.7
2
2.391
110(2)
0.710 73
4.72-32.67
5.549
2329.00(12)
8
1.964
D(calcd) (Mg/m3)
temp (K)
200(2)
0.710 73
4.61-32.61
1.498
100(2)
110(2)
˚
λ (A)
0.710 73
4.07-30.14
2.755
0.710 73
4.98-30.51
1.775
range of θ (deg)
abs coeff (mm-1
)
no. of obsd rflns (I > 2σ)
final R(F) (I > 2σ(I))
8161
13 236
0.0585
0.1739
13 236/105/596
1.177
3428
0.0255
0.0580
3428/0/145
1.059
10 541
0.0412
0.0712
10 541/102/557
0.872
0.0636
0.0978
8161/0/281
1.252
Rw(F2) indices (I > 2σ)
no. of data/restraints/params
goodness of fit on F2
Figure 11. Molecular structure of 23 at the 50% probability level
(H atoms and solvent molecule (EtOH) are omitted for clarity).
˚
Selected bond lengths (A), bond angles (deg), and torsion angles
Figure 12. Molecular structure of 23A at the 50% probability level
˚
(H atoms are omitted for clarity). Selected bond lengths (A), bond
angles (deg), and torsion angles (deg): Te-O=1.876(6), Te-C1A=
(deg): Te-O = 1.864(12), Te-C1A = 2.131(16), Te-C1B =
2.162(8), Te-C1B = 2.136(7), N2B Te=2.813(7), Te-O#1=
3 3 3
2.159(17), N2A Te = 2.714(1), Te-O#1 = 2.623(12); C1A-
3 3 3
2.434(6); C1A-Te-C1B = 90.8(3), N2B Te-O1 = 160.5(2),
3 3 3
Te-C1B = 90.69(6), N2A Te-O = 163.63(5), O-Te-O#1 =
3 3 3
O-Te-O#1 = 76.0(3), C1B-Te-O#1 = 83.3(2), C1A-Te-
O#1=165.6(3).
76.94(5), C1A-Te-O#1 = 85.83(5), C1B-Te-O#1 = 170.70(5).
bonds suggest more contribution of ionic character for
Te N interactions, which is not unusual considering the
electronegativity difference of 1.5 between Te and N.
Table 4. Summary of Theoretical Data for Compounds
Obtained by DFT Calculations and NBO Analysis at the
B3LYP/6-311G(d,p);Lanl2dz(dp) Level
3 3 3
calcd
rTe N (A)
calcd
rTe-X1/X2 (A)
ETe
3 3 3
(kcal/mol)
Conclusion
N
c
c
˚
˚
compd
qTe
3 3 3
In summary, we have successfully accomplished the synth-
esis and structural characterization of a series of tellurium-
(IV) derivatives, including the rare iodobis[2-(phenylazo)-
phenyl-C,N0]telluronium triiodide (14). The hydrolysis of
[2-(phenylazo)phenyl-C,N0]tellurenenyl(IV) trichloride (16)
afforded 20 and 21 as a cocrystal, which represents the first
significant example of monomeric tellurinic acid and its
sodium salt. Also, the tellurenic acid anhydride 22 has been
isolated from the hydrolysis of [2-(phenylazo)phenyl-C,
N0]tellurium(II) chloride. The alkaline hydrolysis of bis-
[2-(phenylazo)phenyl-C,N0]tellurium(IV) dichloride (13) gave
the dimeric telluroxide 23 and partially hydrolyzed product 24.
11
2.795a (2.754)
2.967b (2.821)
2.805a (2.770)
2.983b (2.822)
2.523a (2.476)
2.913b (2.796)
2.776, a 2.954b
2.747 (2.662)
2.724 (2.682)
2.553 (2.494)
2.574 (2.527)
2.827 (2.778)
9.20a
1.476
3.20b
13
14
15
7.79a
1.586
1.422
1.321
2.51b
30.05a
4.35b
2.988, 3.014
9.70,a 3.62b
a Five-membered interaction. b Four-membered interaction (X1 =
X2 = C, Cl, Br, I, O). c Experimental values are given in parentheses.
Structural characterizations indicated that even the presence of
intramolecular interactions does not help in the isolation of the
monomeric telluroxides of the type R2TeO, though a slight

Article
Organometallics, Vol. 30, No. 3, 2011 545
Table 5. Selected Topographical Features of Te N Bonds
3 3 3
a Celite pad and the filtrate was reduced on a rotary evaporator.
The crude product so obtained was purified by column chro-
matography using petroleum ether and ethyl acetate (99:1) as
eluent. The first fraction was azobenzene, followed by telluride
10 (0.40 g, 0.82 mmol) in 17% yield as deep red crystals. Mp:
112-114 °C. 1H NMR (400 MHz, CDCl3): δ 8.04 (dd, 3J = 7.9
Hz, 4J = 1.2 Hz, 2H), 7.95-7.93 (m, 4H), 7.74 (dd, 3J = 7.9 Hz,
4J = 1.2 Hz, 2H), 7.51-7.44 (m, 8H), 7.22 (td, 3J = 10 Hz, 4J =
8.8 Hz, 2H). 13C NMR (400 MHz, CDCl3): δ 154.2, 151.8, 138.3,
131.2, 131.0, 129.4, 128.3, 125.7, 123.1, 122.9, 122.9. 125Te NMR
Computed at the B3LYP/6-311G(d,p)/WTBS Level from the
B3LYP/6-311G(d,p);Lanl2dz(d,p) Optimized Geometryc
2
compd
Fbcp (au)
r Fbcp (au)
H (au)
11
0.0296a
0.0197b
0.0309a
0.0208b
0.0483a
0.0223b
0.0306a
0.0201b
0.074
0.061
0.077
0.063
0.096
0.064
0.076
0.061
0.040
0.028
0.042
0.029
0.068
0.030
0.042
0.028
13
14
15
(300 MHz, CDCl3): δ 667. IR (KBr): ν(NdN) 1583 cm-1
,
ν(C-H) 772 cm-1. ESI-MS: m/z (%) 493 (15) [M þ 1]þ. Anal.
Calcd for C24H18N4Te: C, 58.82; H, 3.70; N, 11.43. Found: C,
58.18; H, 3.34; N, 10.29.
a Five-membered interaction. b Four-membered interaction. c Defini-
2
Synthesis of Bis[2-(phenylazo)phenyl-C,N0]tellurium(IV)
Dichloride (13). A solution of 10 (0.40 g, 0.82 mmol) in dry dichloro-
methane (35 mL) was cooled to 0 °C. To this was added a solution
of sulfuryl chloride (0.10 mL, 1.70 mmol) in dichloromethane
(6 mL) dropwise. After complete addition the mixture was stirred
at this temperature for 20 min. Then it was filtered off and the
volume of filtrate was reduced to get a yellow-orange solid. The
solid was recrystallized from chloroform/hexane (1:2), giving 13
(0.35 g, 0.62 mmol) in 76% yield as orange-red crystals. Mp:
182-184 °C. 1H NMR (400 MHz, CDCl3): δ 8.18-8.14 (m,
4H), 8.07 (d, 3J = 7.1 Hz, 4H), 7.76 (t, 3J = 7.3 Hz, 2H), 7.68 (t,
3J = 7.3 Hz, 2H), 7.60-7.25 (m, 6H). 13C NMR (400 MHz,
CDCl3): δ 151.8, 151.3, 138.8, 135.2, 132.7, 132.6, 132.4, 129.6,
123.8, 121.8. 125Te NMR (300 MHz, CDCl3): δ 835. IR (KBr):
ν(NdN) 1586 cm-1, ν(C-H) 773 cm-1. ESI-MS: m/z (%) 311
(100) [M - C12H12N2Cl2]þ. Anal. Calcd for C24H18Cl2N4Te: C,
51.39; H, 3.23; N, 9.99. Found: C, 51.66; H, 3.04; N, 8.95.
tions: Fbcp = electron density at bond critical point, r Fbcp = Laplacian
of electron density, H = total energy density.
lengthening of the intermolecular Te O distance was ob-
3 3 3
served. The results obtained from computational methods
support the presence of rare four-membered intramolecular
Te N interactions in tellurium derivatives 11, 13, and 14.
3 3 3
Experimental Section
General Experimental Procedures. All experiments were car-
ried out under a dry nitrogen atmosphere using standard
Schlenk techniques unless otherwise noted. Reactions were
monitored by TLC techniques. Solvents were purified and dried
by standard procedures and were freshly distilled under positive
nitrogen pressure prior to use. All the chemicals used were of
reagent grade and were used as received. The starting materials
2-(iodoazo)benzene15 and TeI217 were prepared according to the
reported procedures. Melting points were recorded on a Veego
Synthesis of Bis[2-(phenylazo)phenyl-C,N0]tellurium Dibromide
(11). A solution of 10 (0.40 g, 0.82 mmol) in dry ether (35 mL) was
cooled to 0 °C. To it was added a solution of bromine (0.10 mL,
1.60 mmol) in ether (6 mL) dropwise. After complete addition, the
mixture was stirred at this temperature for 30 min. The precipitate
thus formed was filtered off and dried. The solid was recrystallized
from acetone/hexane, giving 11 (0.40 g, 0.62 mmol) in 75% yield as
1
VMP-I melting point apparatus and are uncorrected. The H
(400.4 MHz) and 13C (100.6 MHz) NMR spectra were recorded
on Varian VXR 400S and Bruker AV 400 instruments at 25 °C.
Tetramethylsilane (SiMe4) was used as an internal standard.
The 125Te (94.7 MHz, 157.97 MHz) NMR spectra were recorded
on Varian VXR 300S and Bruker AMX 500 instruments with
dimethyl telluride (Me2Te) as reference. The FT-IR spectra were
recorded as KBr pellets on a Nicolet Impact 400 FTIR spectrom-
eter. Elemental analysis was performed on a Carlo Erba Model
1106 elemental analyzer. The electrospray mass spectra were
obtained with a Thermo Quest Finnigan LCQDECA ESI-MS
(ion trap) mass spectrometer and Q-Tof micro (YA-105) mass
spectrometer.
1
red crystals. Mp: 130-132 °C. H NMR (400 MHz, CDCl3): δ
8.2-8.16 (m, 4H), 8.09 (d, 3J = 7.0 Hz, 4H), 7.75 (t, 3J = 7.6 Hz,
2H), 7.66 (t, 3J = 7.9 Hz, 2H), 7.62-7.25 (m, 6H). 13C NMR (400
MHz, CDCl3): δ 151.6, 151.3, 136.0, 135.0, 132.8, 132.6, 132.4,
129.7, 123.9, 122.6. 125Te NMR (300 MHz, CDCl3): δ 781. IR
(KBr): ν(NdN) 1573 cm-1, ν(C-H) 772 cm-1. ESI-MS: m/z (%)
311 (85) [M - C12H12N2Br2]þ. Anal. Calcd for C24H18Br2N4Te:
C, 44.36; H, 2.79; N, 8.62. Found: C, 44.36; H, 1.72; N, 8.59.
Synthesis of Iodobis[2-(phenylazo)phenyl-C,N0]telluronium
Triiodide (14). A solution of 10 (0.40 g, 0.82 mmol) in dry
dichloromethane (30 mL) was cooled to 0 °C. To it was added
dropwise a solution of iodine (0.40 g, 1.58 mmol) in carbon
tetrachloride (10 mL). The reaction mixture was stirred at 0 °C
for 20-30 min. Then it was filtered off and reduced to give a
black solid. The solid upon recrystallization from dichloro-
methane/hexane (2:1) gave 14 (0.60 g, 0.60 mmol) in 74% yield
as black crystals. Mp: 153-155 °C. 1H NMR (400 MHz,
Synthesis of (2-(Phenylazo)phenyl-C,N0)tellurium Tribromide12d
(6). To a solution of 714 (4.40 g, 10.55 mmol) in dioxane was added
TeBr4 (4.70 g, 10.50 mmol). The reaction mixture was refluxed for
8 h and then cooled slowly to room temperature. A dark yellow
precipitate along with some dark brown crystalline material was
obtained. The reaction mixture was filtered off, washed with metha-
nol, and dried under vacuum to yield pure 6 (2.80 g, 5.10 mmol) in
48% yield as a red-brown crystalline solid. Mp: above 250 °C. 1H
NMR (400 MHz, CDCl3): δ 8.59 (s, 1H), 8.52-8.47 (m, 1H), 8.08
(d, 3J= 6.7 Hz, 2H), 7.94 (d, 3J= 7.3 Hz, 2H), 7.74 (d, 3J=7.3Hz,
1H), 7.67 (t, 2H). 13C NMR (400 MHz, CDCl3): δ 146.8, 136.9,
136.7, 135.2, 134.9, 133.3, 133.2, 131.3, 130.7, 129.5, 123.4. 125Te
NMR (500 MHz, DMSO-d6): δ 1330, 1317, 1306, 1277. IR (KBr):
ν(NdN) 1573 cm-1, ν(C-H) 775 cm-1. ESI-MS: m/z (%) 551 (15)
[M þ 1]þ, 311 (100) [M - Br3]þ. Anal. Calcd for C12H9 Br3N2Te:
C, 26.28; H, 1.65; N, 5.11. Found: C, 26.93; H, 1.42; N, 5.34.
Synthesis of Bis[2-(phenylazo)phenyl-C,N0]telluride (10). To a
solution of 8 (3.00 g, 9.74 mmol) in dry ether (40-50 mL) was
added dropwise a solution of n-BuLi (6.70 mL, 10.7 mmol)
at -114 °C. The reaction mixture was stirred for 30 min at this
temperature. TeI217 (1.80 g, 4.72 mmol) was added portionwise
to the reaction mixture. The reaction mixture was warmed to
room temperature. After it was stirred for 7 h at this temperature
(monitored via TLC), the reaction mixture was filtered through
3
3
DMSO-d6): δ 8.41 (d, J = 7.5 Hz, 2H), 7.98 (t, J = 6.9 Hz,
2H), 7.88-7.84 (m, 6H), 7.69-7.64 (m, 4H), 7.55 (t, 3J = 7.9 Hz,
4H). 13C NMR (400 MHz, DMSO-d6): δ 151.2, 149.1, 135.0,
134.1, 133.8, 131.9, 130.1, 128.5, 123.0. 125Te NMR (300 MHz,
DMSO-d6): δ 1163. IR (KBr): ν(NdN) 1573 cm-1, ν(C-H) 772
cm-1. ESI-MS: m/z (%) 311 (10) [M - C12H9I3N2]þ. Anal.
Calcd for C24H18I4N4Te: C, 28.89; H, 1.82; N, 5.62. Found: C,
28.82; H, 1.58; N, 5.71.
Synthesis of Bis[2-(phenylazo)phenyl-C,N0]ditellurium Dichlo-
ride (19). To the suspension of 1613 (2.00 g, 4.82 mmol) in
ethanol was added dropwise a solution of hydrazine hydrate
(1.40 mL, 28.8 mmol) in ethanol (10 mL) under reflux. After
complete addition, the reaction mixture was cooled to 0 °C.
Ditelluride16 18, which precipitated as a dark brown powder
(0.61 g, 0.99 mmol) in 41% yield, was filtered off, and the filtrate

546 Organometallics, Vol. 30, No. 3, 2011
Srivastava et al.
when left to stand overnight gave 19 (0.22 g, 0.31 mmol) in 37%
yield as a red-black crystalline soild. Mp: 100-102 °C. 1H NMR
(400 MHz, CDCl3): δ 8.52 (dd, 3J = 7.9 Hz, 4J = 1.2 Hz, 1H),
8.24 (dd, 3J = 7.6, 4J = 1.3 Hz, 1H), 8.05-8.01 (m, 2H), 7.81
(dd, 3J = 7.3 Hz, 4J = 1.2 Hz, 1H), 7.56-7.50 (m, 4H), 7.41 (dt,
hydroxide aqueous solution (10 mL) was refluxed for 2.5 h. Then,
a few drops of ethanol was added and the solution was filtered
hot. When the reaction mixture was cooled, 23 (0.53 g, 0.98 mmol)
was obtained as orange-red crystals in 78% yield. Mp: 138-140 °C.
3
4
1H NMR (400 MHz, CD3OD): δ 8.24 (dd, J = 7.9 Hz, J =
1.2 Hz, 2H), 7.86 (dd, 3J=7.3Hz, 4J=4.5Hz, 4H), 7.81-7.75 (m,
5H), 7.65 (dt, 3J = 7.6 Hz, 4J = 1.2 Hz, 1H), 7.55-7.50 (m, 2H),
7.43 (td, 3J = 7.9 Hz, 4J = 1.5 Hz, 4H), 3.60 (q, 3J = 7.0 Hz, 2H),
1.17 (t, 3J = 7.0 Hz, 3H). 13C NMR (400 MHz, CD3OD): δ 153.3,
151.9, 134.7, 134.1, 134.0, 132.6, 130.8, 125.5, 124.2, 58.4,
18.5. 125Te NMR (500 MHz, CDCl3): δ 1228. IR (KBr): ν(O-H)
3439 cm-1, ν(NdN) 1585 cm-1, ν(C-H) 773 cm-1, ν(TedO)
718 cm-1. ESI-MS: m/z (%) 509 (15) [M þ 2]þ. Anal. Calcd for
C26H22N4O2Te: C, 56.77; H, 4.03; N, 10.19. Found: C, 55.96; H,
3.91; N, 10.22.
4
3J = 6.7 Hz, J = 1.2 Hz, 1H), 7.13-7.06 (m, 3H), 6.88 (dd,
3J = 8.2 Hz, 4J = 1.2 Hz, 1H), 6.80-6.76 (m, 3H), 6.55 (dt, 3J =
7.6 Hz, 4J = 1.2 Hz, 1H), 6.35 (s, 1H), 5.64 (s, 1H). 13C NMR
(400 MHz, CDCl3): δ 153.2, 150.8, 149.7, 148.7, 142.7, 140.2,
134.2, 131.8, 131.6, 131.4, 131.3, 130.2, 129.8, 129.6, 129.4,
127.9, 127.7, 123.2, 123.0, 120.6, 120.0, 112.7, 111.3. 125Te
NMR (300 MHz, CDCl3): δ 1224, 836. IR (KBr): ν(NdN)
1580 cm-1, ν(C-H) 769 cm-1. ESI-MS: m/z (%) 688 (6) [M -
2]þ. Anal. Calcd for C24H22Cl2N6Te2: C, 40.00; H, 3.08; N,
11.66. Found: C, 40.82; H, 3.00; N, 11.01.
Synthesis of (2-(Phenylazo)phenyl-C,N0)tellurinic Acid (20)
and Its Sodium Salt (21) Cocrystal. A suspension of 16 (1.00 g,
2.41 mmol) in 2 M sodium hydroxide (6 mL) was refluxed for
2.5 h. To this was then added absolute ethanol (2 mL), and the
solution was filtered hot. When the reaction mixture was cooled,
deep orange needle-shaped cocrystals of 20 and 21 precipitated
and were washed with hexane and dried to obtain the pure
compound (0.81 g, 0.43 mmol) in 72% yield as a red solid. Mp:
Synthesis of Dichlorobis[2-(phenylazo)phenyl-C,N0]tellurium-
(IV) Oxide (24). To a solution of 13 (0.20 g, 0.36 mmol) in
dichloromethane (5-6 mL) was added a solution of sodium
carbonate in distilled water (deoxygenated) (2 mL) under an
inert atmosphere. The mixture was stirred at room temperature
for 24 h and filtered off. The organic phase was washed with
water, dried, and evaporated to give 24 (0.16 g, 0.14 mmol) in
79% yield as a yellow-orange solid. Mp: 135-137 °C. 1H NMR
(400 MHz, CDCl3): δ 8.13 (dd, 3J = 7.9 Hz, 4J = 1.2 Hz, 4H),
7.92 (d, 3J = 7.0 Hz, 4H), 7.84 (d, 3J = 7.3 Hz, 8H), 7.65 (td,
3J = 7.6 Hz, 4J = 1.3 Hz, 4H), 7.57 (td, 3J = 7.3 Hz, 4J = 1.0
Hz, 4H), 7.45 (tt, 3J = 15.8 Hz, 4J = 7.4 Hz, 4H), 7.36 (t, 3J =
7.9 Hz, 8H). 13C NMR (400 MHz, CDCl3): δ 151.8, 151.0, 134.5,
133.2, 132.4, 132.1, 131.8, 129.5, 126.2, 123.3. 125Te NMR (300
MHz, CDCl3): δ 1243. IR (KBr): ν(NdN) 1585 cm-1, ν(C-H)
772 cm-1, ν(TedO) 714 cm-1. ESI-MS: m/z (%) 506.85 (100)
[M - C25H18Cl2N4O3Te]þ. Anal. Calcd for C48H38Cl2N8O4Te2:
C, 51.61; H, 3.43; N, 10.03. Found: C, 51.69; H, 3.25; N, 10.95.
The crystal of 24 upon analysis turned out to be the dimer 23A.
Mp: 141-143 °C.
1
102-104 °C. H NMR (400 MHz, CD3OD): δ 8.41-8.39 (m,
2H), 8.18-8.15 (m, 2H), 8.06-8.03 (m, 4H), 7.72 (t, 3J = 3.4 Hz,
4H), 7.59-7.58 (m, 6H). 13C NMR (400 MHz, CD3OD): δ
153.4, 152.4, 141.9, 133.3, 132.7, 130.6, 129.8, 129.0, 124.2. 125Te
NMR (500 MHz, CD3OD): δ 1611. IR (KBr): ν(O-H) 3428
cm-1, ν(NdN) 1626 cm-1, ν(TedO) 772 cm-1. ESI-MS: m/z
(%) 831(30) [M - C24H54N4Na2O22Te2]þ. Anal. Calcd for
C48H87N8Na3O33Te4: C, 30.61; H, 4.66; N, 5.95. Found: C,
29.82; H, 4.02; N, 6.03.
Synthesis of Bis[(2-(phenylazo)phenyl-C,N0)tellurium] Oxide
(22). To a solution of 17 (0.50 g, 1.45 mmol) in tetrahydrofuran
(6 mL) was added 4 mL of 2 M sodium hydroxide solution in
distilled water dropwise. The addition led to a color change from
yellow to deep purple. The reaction mixture was stirred at room
temperature for nearly 24 h. On removal of the solvent, the crude
solid obtained was dissolved in chloroform and this solution was
washed with water and then dried. The purple sticky solid obtained
was triturated with pentane and dried to give 22 (0.37 g, 0.58 mmol)
in 80% yield as a purple solid. Mp: 92-93 °C. 1H NMR (400 MHz,
CD3OD): δ 8.62 (d, 3J = 6.7 Hz, 2H), 8.24 (d, 3J = 7.0 Hz, 2H),
Acknowledgment. This work was supported by the
Department of Science and Technology (DST), New Delhi,
No. 110016 (India). K.S. is grateful to the CSIR for
SRF, to the TIFR (Mumbai) for 125Te NMR, and to
Mr. B. T. Kansara for ESI-MS data.
8.01 (d, 3J = 6.4 Hz, 4H), 7.64-7.33 (m, 6H), 7.56 (bs, 4H). 13
C
Supporting Information Available: Text, figures, and tables
giving packing diagrams for 12-14, Naþ-water packing dia-
gram and superimposition figure of 20-21, spectral data
(elemental analysis, 1H, 13C, and 125Te NMR, FT-IR, ES-MS)
for 6, 10, 11, 13, 14, 19, 20-21, and 22-24, optimized geometries
and coordinates of 11 and 13-15, and AIM molecular graph of
11 and 13-15 and CIF files giving X-ray crystallographic data
of 6, 10-14, 17, 19, 20-21, 22, 23, and 23A. This material is
available free of charge via the Internet at http://pubs.acs.org.
NMR (400 MHz, CDCl3):δ153.8, 150.4, 139.6, 133.4, 130.8, 130.4,
129.7, 129.5, 129.4, 129.2, 126.8, 123.1, 121.9. 125Te NMR (500
MHz, CDCl3):δ1535. IR (KBr): ν(NdN) 1580 cm-1, ν(C-H) 768
cm-1, ν(Te-O) 713 cm-1. ESI-MS: m/z (%) 310 (100) [M -
C12H9TeO]þ. Anal. Calcd for C24H18N4OTe2: C, 45.49; H, 2.86; N,
8.84. Found: C, 45.37; H, 2.62; N, 8.89.
Synthesis of Bis[2-(phenylazo)phenyl-C,N0]tellurium(IV)
Oxide (23). A suspension of 13 (0.70 g, 1.25 mmol) in 2 M sodium