Tribromo(3,5-dimethyl-2-nitro-phenyl-κ2C 1,O)tellurium(IV), bromo(3,5-dimethyl-2-nitro-phenyl-κ 2C1,O)tellurium(II) and bromo(3,5-dimethyl-2-nitroso-phenyl-κ2C 1,O)tellurium(II)

Article abstract of DOI:10.1107/S0108270103017955

The properties of intramolecularly coordinated organotellurium compounds were studied. The compounds were found to exhibit high degrees of intramolecular Te-O coordination. It was observed that the coordination could stabilize the unstable low-valent orga

Full text of DOI:10.1107/S0108270103017955

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
nitrophenyl)tellurium(IV) (Wiriyachitra et al., 1979) also
feature strong intramolecular TeÐO coordination, but no
structural information has been made available for these
compounds to date. Compounds carrying ortho nitro, nitroso
and amino functionalities are of interest as potential precur-
sors to compounds featuring coordinatively stabilized tell-
uronium cations and as intermediates to organotellurium
heterocycles (Junk & Irgolic, 1988).
Recent advances in the synthesis of substituted diaryl-
ditelluriums by selective ortho nitration, as well as from
boronic acid precursors (Clark et al., 2002), have provided
easier access to compounds such as bis(3,5-dimethyl-2-nitro-
phenyl)ditellurium, which is employed in this study. Bis(3,5-
dimethyl-2-nitrophenyl)ditellurium was prepared by nitration
of bis(3,5-dimethylphenyl)ditellurium to 3,5-dimethyl-2-
nitrobenzenetellurinic acid nitrate, followed by reduction (see
®rst Scheme below).
ISSN 0108-2701
Tribromo(3,5-dimethyl-2-nitro-
phenyl-j2C1,O)tellurium(IV),
bromo(3,5-dimethyl-2-nitro-
phenyl-j2C1,O)tellurium(II) and
bromo(3,5-dimethyl-2-nitroso-
phenyl-j2C1,O)tellurium(II)
Prabodhika Mallikaratchy,a Richard E. Norman,a
Frank R. Fronczekb and Thomas Junka*
aChemistry Department, CNSB-210, University of Louisiana at Monroe, LA 71209,
USA, and bDepartment of Chemistry, Louisiana State University, Baton Rouge, LA
70803, USA
Correspondence e-mail: junk@ulm.edu
Received 10 July 2003
Accepted 12 August 2003
Online 23 September 2003
All three title compounds, prepared from bis(3,5-dimethyl-2-
nitrophenyl)ditellurium, exhibit high degrees of intramol-
ecular TeÐO coordination. Their TeÐO distances increase in
the order C8H8BrNOTe < C8H8BrNO2Te < C8H8Br3NO2Te,
Ê
with distances of 2.165 (3), 2.306 (1) and 2.423 (6) A, respec-
tively, indicating that C8H8BrNOTe may be more aptly
described as 1-bromo-4,6-dimethyl-2,1,3-benzoxatellurazole.
Treatment of bis(3,5-dimethyl-2-nitrophenyl)ditellurium
with stoichiometric amounts of bromine produced tribromo-
(3,5-dimethyl-2-nitrophenyl-ꢀ2C,O)tellurium(IV), (I), bromo-
(3,5-dimethyl-2-nitrophenyl-ꢀ2C,O)tellurium(II), (II), and
bromo(3,5-dimethyl-2-nitrosophenyl-ꢀ2C,O)tellurium(II), (III),
which may be described as heterocyclic (a substituted
benzoxatellurazole).
Comment
Intramolecularly coordinated organotellurium compounds
commonly exhibit properties that are signi®cantly different
from those of their non-coordinated counterparts. Moieties
through which a Lewis basic atom intramolecularly coordi-
nates to tellurium include azo, imino, carbonyl and amino
functionalities (Detty & O'Regan, 1994). This coordination
can stabilize otherwise unstable low-valent organotellurium
halides and pseudohalides (Cobbledick et al., 1979; Detty et al.,
1989; Sadekov et al., 1990; Menon et al., 1996), as well as
telluronium cations (Fujihara et al., 1995). Intramolecular
coordination by nitroso and nitro moieties has not been
documented in much detail because of limited access to these
classes of organotellurium compounds. Thus, the only
published procedure for the preparation of an ortho-nitro-
substituted diphenylditellurium compound (Wiriyachitra et al.,
1979) was found to be challenging. The few reported examples
of NO and NO2 coordination include dioxatellurapentalenes
(Perrier & Vialle, 1971) and 1-nitroso-2-naphthyltellurium
monohalides found in the patent literature (Gunther & Lok,
1986; Przyklek-Elling et al., 1987). It appears highly prob-
able that bromo(2-nitrophenyl)tellurium(II) and tribromo(2-
There are two molecules of (I), of nearly identical geometry,
in the asymmetric unit (Fig. 1). There appears to be a non-
crystallographic center of symmetry between the two inde-
pendent molecules (at about x = 0.105, y = 0.248 and z = 12 ).
Similar centers appear in more than 65% of Pca21 structures
in which Z is greater than 4 (Marsh et al., 1998) and often
result in unusual correlations between corresponding atoms in
the two molecules. Since the average values of equivalent
bond distances are apparently unaffected by this pseudo-
symmetry (Marsh et al., 1998), we discuss the average case.
The geometry about the Te atom is square pyramidal, with the
basal plane de®ned by three Br atoms and an O atom. A C
atom is in the axial position, and a stereochemical lone pair is
Acta Cryst. (2003). C59, o571±o574
DOI: 10.1107/S0108270103017955
# 2003 International Union of Crystallography o571

organic compounds
located trans to this C atom. The Te atom sits `below' the basal
plane, which is consistent with the principles of VSEPR
(valence-shell electron-pair repulsion) theory. The TeÐBr
distance for the Br atom trans to atom O1 is signi®cantly
Ê
shorter than the other TeÐBr distances [2.5047 (12) A versus
Ê
2.6540 (11) and 2.6754 (11) A; Table 1]. The Te1ÐC1 bond
Ê
distance [2.132 (7) A] is in good agreement with those
reported for non-coordinated aryl±Te bonds, e.g. in catena-ꢁ-
Ê
bromo-dibromo(phenyl)tellurium(IV) [2.140 (8) A; Alcock &
Harrison, 1982a]. The O1ÐTe1ÐC1 angle is constrained to
71.8 (2)ꢁ by the ®ve-membered ring. These structural features
are similar to those reported for trichloro(2-phenylazo-
phenyl-C,N0)tellurium(IV), in which there is coordination of
tellurium by the N atom of the azo group (Ahmed et al.,
1985a). There is a short intermolecular contact in (I) between
atoms O2A and N1B, which is reminiscent of the perpendi-
cular motif found for carbonyl±carbonyl interactions (Allen et
al., 1998).
Figure 3
The molecular structure of (III), with displacement ellipsoids drawn at
the 50% probability level.
The geometries of (II) and (III) are `T-shaped' about the Te
atom, with the OÐTeÐBr angles being distinctly non-linear
[168.80 (14) and 169.57 (9)ꢁ, respectively; Tables 2 and 3, and
Figs. 2 and 3] and the bromide ion displaced towards the
phenyl ring, which geometry is again consistent with VSEPR
theory and the presence of two stereochemical lone pairs of
electrons on the TeII centers. The NÐO distance in (III)
Ê
[1.315 (5) A] is signi®cantly longer than the analogous
Ê
distance in (II) [1.268 (8) A], which is in turn signi®cantly
longer than the other (non-coordinated) NÐO distance of
Ê
1.208 (8) A. The TeÐC distance of 2.098 (6) A in (II) is the
Ê
same as that found in bromo(2-phenylazophenyl-C,N)-
Ê
tellurium(II) [2.092 (8) A; Majeed et al., 1997], while the TeÐ
Ê
C distance is shortened to 2.038 (4) A in (III).
Ê
The TeÐO bond distances of 2.307 (6) A in (II) and
Ê
2.165 (3) A in (III) are shorter than the TeÐO distance of
Ê
2.423 (6) A for (I) and are comparable to TeÐO distances
Ê
observed for amides [e.g. 2.237 (8) A for bromo(2-amido-
phenyl-C,O)tellurium(II); Dupont et al., 1979], for carboxyl-
0
Ê
ates [e.g. 2.167 (4) A for acetato(2-phenylazophenyl-C,N )-
tellurium(II); Ahmed et al., 1985b] and for nitrates [e.g.
Ê
2.171 (3) A for diphenyltellurium(IV) dinitrate; Alcock &
Harrison, 1982b].
The relative ease with which (I) was reduced to (III) is
indicative of the high stability of ortho-nitroso-stabilized
aryltellurium subhalides. In practice, exposure of the
tellurium(IV) compound to a variety of ketones and alcohols
resulted in gradual color changes indicative of reduction.
Figure 1
The molecular structure of (I), with displacement ellipsoids drawn at the
50% probability level.
Experimental
All of the title compounds were prepared from bis(3,5-dimethyl-
phenyl)ditellurium, accessible via the Haller±Irgolic method (Haller
& Irgolic, 1972). This compound was converted to bis(3,5-dimethyl-2-
nitrophenyl)ditellurium by nitration and subsequent reduction
(Nair, 2002). For the preparation of (I), bis(3,5-dimethyl-2-nitro-
phenyl)ditellurium (1.0 g, 1.8 mmol) was dissolved in carbon tetra-
chloride (30 ml). A solution of bromine (10% w/w) in carbon
tetrachloride was added slowly, and a gradual darkening to magenta
was observed, followed by a sharp color change to yellow. Addition of
Figure 2
The molecular structure of (II), with displacement ellipsoids drawn at the
50% probability level.
ꢀ
o572 Prabodhika Mallikaratchy et al.
C8H8Br3NO2Te, C8H8BrNO2Te and C8H8BrNOTe
Acta Cryst. (2003). C59, o571±o574

organic compounds
Table 1
Selected geometric parameters (A, ) for (I).
bromine was discontinued and the product was crystallized by open-
air evaporation. In contrast to non-coordinated aryltellurium triha-
lides, this compound was found to be insensitive to moisture (yield
ꢁ
Ê
Te1AÐC1A
Te1AÐO1A
Te1AÐBr1A
Te1AÐBr2A
Te1AÐBr3A
O1AÐN1A
O2AÐN1A
N1AÐC2A
2.138 (7)
2.448 (6)
2.5165 (12)
2.6495 (11)
2.6731 (11)
1.236 (8)
1.212 (8)
1.466 (9)
Te1BÐC1B
Te1BÐO1B
Te1BÐBr1B
Te1BÐBr3B
Te1BÐBr2B
O1BÐN1B
O2BÐN1B
N1BÐC2B
2.127 (7)
2.398 (6)
2.4929 (12)
2.6584 (10)
2.6776 (11)
1.271 (8)
1.218 (9)
1.464 (9)
1
quantitative; m.p. 467±469 K). H NMR (CDCl3, p.p.m.): 2.58 (3H),
2.80 (3H), 7.51 (1H), 8.41 (1H); 13C NMR (CDCl3, p.p.m.): 22.5, 22.7,
129.5, 136.0, 137.5, 138.1, 140.8, 151.4.
For the preparation of (II), bis(3,5-dimethyl-2-nitrophenyl)-
ditellurium (1.0 g, 1.8 mmol) was dissolved in carbon tetrachloride
(30 ml). One third of the previously prepared ditellurium solution
was converted to a solution of the tribromide by addition of bromine
as above. Subsequently, the tribromide solution was combined with
the remaining two parts of the bis(3,5-dimethyl-2-nitrophenyl)-
ditellurium solution. Equilibration to the desired monobromide
occurred rapidly. The crude product was collected by open-air
evaporation of the solvent and recrystallized from cyclohexane
C1AÐTe1AÐO1A
C1AÐTe1AÐBr1A
O1AÐTe1AÐBr1A
C1AÐTe1AÐBr2A
O1AÐTe1AÐBr2A
Br1AÐTe1AÐBr2A
C1AÐTe1AÐBr3A
O1AÐTe1AÐBr3A
Br1AÐTe1AÐBr3A
Br2AÐTe1AÐBr3A
N1AÐO1AÐTe1A
C6AÐC1AÐTe1A
C2AÐC1AÐTe1A
71.3 (2)
94.7 (2)
165.75 (12)
85.6 (2)
84.59 (17)
92.08 (4)
85.4 (2)
89.08 (17)
92.27 (4)
170.27 (3)
114.1 (5)
121.1 (6)
118.9 (5)
C1BÐTe1BÐO1B
C1BÐTe1BÐBr1B
O1BÐTe1BÐBr1B
C1BÐTe1BÐBr3B
O1BÐTe1BÐBr3B
Br1BÐTe1BÐBr3B
C1BÐTe1BÐBr2B
O1BÐTe1BÐBr2B
Br1BÐTe1BÐBr2B
Br3BÐTe1BÐBr2B
N1BÐO1BÐTe1B
C6BÐC1BÐTe1B
C2BÐC1BÐTe1B
72.2 (2)
94.3 (2)
166.60 (12)
84.41 (19)
85.96 (15)
92.86 (4)
86.66 (19)
87.63 (15)
91.68 (4)
170.26 (3)
114.0 (4)
121.7 (5)
119.6 (5)
1
(brown±red needles; yield 1.06 g, 82%; m.p. 380±381 K). H NMR
(CDCl3, p.p.m.): 2.43 (3H), 2.79 (3H), 7.19 (1H), 8.15 (1H); 13C NMR
(CDCl3, p.p.m.): 21.9, 23.0, 131.8, 133.2, 134.1, 140.5, 144.3, 146.8. Well
formed crystals were obtained by slow open-air evaporation of a
solution in dichloromethane.
For the preparation of (III), a stirred solution of (I) (0.2 g,
0.4 mmol) in acetone (20 ml) and 2-propanol (20 ml) was heated to
re¯ux for 24 h. A color change from yellow to blue was noticed. The
blue solid remaining after open-air evaporation under the hood was
taken up in carbon tetrachloride, and the well formed purple crystals
remaining after open-air evaporation were collected (yield 42 mg,
32%; m.p. 430±431 K). 1H NMR (CDCl3, p.p.m.): 2.36 (3H), 2.99
(3H), 7.26 (1H), 8.35 (1H); 13C NMR (CDCl3, p.p.m.): 18.9, 23.3,
132.4, 133.7, 138.1, 146.2, 149.1, 154.41.
Compound (II)
Crystal data
3
C8H8BrNO2Te
Mr = 357.66
Dx = 2.278 Mg m
Mo Kꢂ radiation
Cell parameters from 25
re¯ections
Monoclinic, I2=a
Ê
a = 14.175 (4) A
ꢃ = 10.6±18.8ꢁ
Ê
b = 9.582 (2) A
1
Ê
c = 15.433 (4) A
ꢁ = 6.65 mm
T = 298 K
ꢆ = 95.70 (2)ꢁ
V = 2085.8 (9) A
Z = 8
3
Ê
Parallelepiped, brown±red
0.35 Â 0.22 Â 0.20 mm
Compound (I)
Data collection
Crystal data
Enraf±Nonius CAD-4
diffractometer
ꢃ/2ꢃ scans
Absorption correction: scan
(North et al., 1968)
Tmin = 0.202, Tmax = 0.266
7028 measured re¯ections
2393 independent re¯ections
1325 re¯ections with I > 2ꢄ(I)
Rint = 0.043
ꢃmax = 27.5ꢁ
C8H8Br3NO2Te
Mr = 517.48
Orthorhombic, Pca21
Mo Kꢂ radiation
Cell parameters from 28 416
re¯ections
h = 18 ! 18
k = 11 ! 12
l = 0 ! 20
ꢃ = 2.5±32.0ꢁ
Ê
a = 7.371 (2) A
1
Ê
b = 12.139 (5) A
ꢁ = 11.81 mm
T = 120 K
3 standard re¯ections
frequency: 120 min
intensity decay: 0.8%
Ê
c = 28.274 (11) A
Ê
V = 2529.9 (16) A
3
Prism, yellow
0.20 Â 0.17 Â 0.15 mm
Z = 8
Dx = 2.717 Mg m
3
Re®nement
Re®nement on F2
R[F2 > 2ꢄ(F2)] = 0.043
wR(F2) = 0.104
S = 1.10
2393 re¯ections
w = 1/[ꢄ2(F2o) + (0.0117P)2
+ 3.15P]
Data collection
Nonius KappaCCD diffractometer
(with an Oxford Cryosystems
Cryostream cooler)
! scans with ꢀ offsets
Absorption correction: multi-scan
(HKL SCALEPACK;
Otwinowski & Minor, 1997)
Tmin = 0.108, Tmax = 0.170
28 416 measured re¯ections
4303 independent re¯ections
3800 re¯ections with I > 2ꢄ(I)
Rint = 0.032
where P = (F2o + 2Fc2)/3
(Á/ꢄ)max = 0.003
3
Ê
Áꢅmax = 0.95 e A
ꢃ
max = 32.0ꢁ
3
Ê
0.81 e A
121 parameters
H-atom parameters constrained
Áꢅmin
Extinction correction: SHELXL97
=
h = 10 ! 10
k = 18 ! 18
l = 41 ! 41
Extinction coef®cient: 0.00020 (7)
Table 2
Selected geometric parameters (A, ) for (II).
ꢁ
Ê
TeÐC1
TeÐO1
TeÐBr
2.098 (6)
2.307 (6)
2.5584 (12)
O1ÐN
O2ÐN
NÐC2
1.268 (8)
1.208 (8)
1.445 (9)
Re®nement
Re®nement on F2
R[F2 > 2ꢄ(F2)] = 0.035
wR(F2) = 0.087
(Á/ꢄ)max < 0.001
3
Ê
Áꢅmax = 2.77 e A
3
Ê
2.44 e A
Áꢅmin
=
C1ÐTeÐO1
C1ÐTeÐBr
O1ÐTeÐBr
NÐO1ÐTe
O2ÐNÐO1
O2ÐNÐC2
73.4 (2)
95.38 (18)
168.80 (14)
115.1 (4)
120.6 (7)
122.4 (7)
O1ÐNÐC2
C6ÐC1ÐC2
C6ÐC1ÐTe
C2ÐC1ÐTe
C1ÐC2ÐN
C3ÐC2ÐN
117.1 (6)
118.4 (6)
123.5 (5)
118.1 (5)
116.3 (7)
120.4 (6)
S = 1.01
4303 re¯ections
272 parameters
H-atom parameters constrained
w = 1/[ꢄ2(F2o) + (0.0533P)2]
where P = (F2o + 2Fc2)/3
Extinction correction:
SHELXL97
Extinction coef®cient:
0.00162 (17)
ꢀ
Acta Cryst. (2003). C59, o571±o574
Prabodhika Mallikaratchy et al.
C8H8Br3NO2Te, C8H8BrNO2Te and C8H8BrNOTe o573

organic compounds
Table 3
Selected geometric parameters (A, ) for (III).
The authors thank Dr W. J. Catallo, Dr P. R. Alburquerque
and Ms R. Nair for their assistance. The purchase of the
diffractometers was made possible by a National Science
Foundation chemical instrumentation grant and grants No.
LEQSF(1996-97)-ESH-TR-10 and LEQSF(1999±2000)-ESH-
TR-13, administered by the Louisiana Board of Regents.
ꢁ
Ê
Te1ÐC1
Te1ÐO1
Te1ÐBr1
2.038 (4)
2.165 (3)
2.6401 (16)
O1ÐN1
N1ÐC2
1.315 (5)
1.348 (5)
C1ÐTe1ÐO1
C1ÐTe1ÐBr1
O1ÐTe1ÐBr1
N1ÐO1ÐTe1
O1ÐN1ÐC2
76.81 (14)
92.76 (11)
169.57 (9)
116.6 (3)
C6ÐC1ÐC2
C6ÐC1ÐTe1
C2ÐC1ÐTe1
N1ÐC2ÐC3
N1ÐC2ÐC1
118.6 (3)
129.2 (3)
112.2 (3)
118.0 (4)
120.8 (4)
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SQ1028). Services for accessing these data are
described at the back of the journal.
113.5 (4)
References
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Crystal data
3
C8H8BrNOTe
Mr = 341.66
Monoclinic, C2=c
a = 11.291 (6) A
b = 12.788 (5) A
Ê
c = 14.332 (7) A
ꢆ = 112.62 (3)ꢁ
V = 1910.2 (16) A
Z = 8
Dx = 2.376 Mg m
Mo Kꢂ radiation
Cell parameters from 4719
re¯ections
Ê
Ê
ꢃ = 2.5±32.0ꢁ
ꢁ = 7.25 mm
T = 120 K
1
3
Ê
Prism, dark red
0.20 Â 0.15 Â 0.15 mm
Data collection
Nonius KappaCCD diffractometer
(with an Oxford Cryosystems
Cryostream cooler)
! scans with ꢀ offsets
Absorption correction: multi-scan
(HKL SCALEPACK;
4540 measured re¯ections
3272 independent re¯ections
2511 re¯ections with I > 2ꢄ(I)
Rint = 0.032
ꢃ
max = 32.0ꢁ
h = 16 ! 16
k = 18 ! 13
l = 20 ! 21
Otwinowski & Minor, 1997)
Tmin = 0.268, Tmax = 0.337
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Flack, H. D. (1983). Acta Cryst. A39, 876±881.
Re®nement
Re®nement on F2
R[F2 > 2ꢄ(F2)] = 0.040
wR(F2) = 0.123
S = 1.09
3272 re¯ections
w = 1/[ꢄ2(F2o) + (0.0702P)2]
where P = (F2o + 2Fc2)/3
(Á/ꢄ)max = 0.001
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3
Ê
Áꢅmax = 1.30 e A
3
Ê
2.03 e A
Áꢅmin
Extinction correction: SHELXL97
=
112 parameters
H-atom parameters constrained
Extinction coef®cient: 0.00086 (19)
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H atoms were treated as riding in idealized positions, with CÐH
Ê
distances of 0.93±0.98 A, depending on atom type and temperature.
A torsional parameter was re®ned for each methyl group. Displace-
ment parameters for H atoms were assigned as 1.2Ueq of the attached
atom (1.5 for methyl groups). Friedel pairs were averaged for (I),
since re®nement of the Flack (1983) parameter led to a value of
0.509 (8), indicative of a racemic twin. The largest residual peak was
Nair, R. R. (2002). MS thesis, University of Louisiana at Monroe, USA.
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North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351±
359.
Ê
Ê
1.45 A from atom Br3B for (I), 0.83 A from the Te atom for (II) and
Ê
0.55 A from atom Te1 for (III).
For compounds (I) and (III), data collection: COLLECT (Nonius,
2000); cell re®nement: HKL DENZO and SCALEPACK (Ot-
winowski & Minor, 1997); data reduction: HKL DENZO and
SCALEPACK. For compound (II), data collection: CAD-4
EXPRESS (Enraf±Nonius, 1994); cell re®nement: CAD-4 EXPRESS;
data reduction: maXus (Mackay et al., 1999). Program(s) used to
solve structure: SIR97 (Altomare et al., 1999) for (I) and (II), and
SIR92 (Altomare et al., 1994) for (III). For all three compounds,
program(s) used to re®ne structure: SHELXL97 (Sheldrick, 1997);
molecular graphics: ORTEPII (Johnson, 1976).
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276,
Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M.
Sweet, pp. 307±326. New York: Academic Press.
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Sadekov, I. D., Maksimenko, A. A., Maslakov, A. G. & Minkin, V. I. (1990). J.
Organomet. Chem. 391, 179±188.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of
GoÈttingen, Germany.
Wiriyachitra, P., Falcone, S. J. & Cava, M. P. (1979). J. Org. Chem. 44, 3957±
3959.
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o574 Prabodhika Mallikaratchy et al.
C8H8Br3NO2Te, C8H8BrNO2Te and C8H8BrNOTe
Acta Cryst. (2003). C59, o571±o574