Pyramidal inversion isomers in the solid-state structure of the tricyclic antimony-tellurium imido complex TeSb2Cl2(NtBu)4

Article abstract of DOI:10.1021/ic0109694

The reaction of ^tBuNTe(μ-N^tBu)₂TeN^tBu with ClSb(μ-N^tBu)₂SbCl in toluene produces the tricyclic complex {[^tBuNSb (μ-N^tBu)₂TeN^tBu] (μ-SbCl)}Cl

Full text of DOI:10.1021/ic0109694

Inorg. Chem. 2002, 41, 1002−1006
Pyramidal Inversion Isomers in the Solid-State Structure of the Tricyclic
t
Antimony−Tellurium Imido Complex TeSb2Cl2(N Bu)4
Tristram Chivers* and Gabriele Schatte
Department of Chemistry, UniVersity of Calgary, Calgary, Alberta, Canada T2N 1N4
Received September 12, 2001
Introduction
with our studies of the reactivity of 1, we considered whether
mixed antimony-tellurium imido systems could be generated
from 1 and 2. We report here that this reaction generates
the tricyclic complex {[tBuNSb(µ-NtBu)2TeNtBu](µ3-Sb-
Cl)}+Cl- (3) which, in the solid state, is obtained as a mixture
of pyramidal inversion isomers. The structure of Cl2Te(µ-
NtBu)2Sb[N(H)tBu] (4), a byproduct of this reaction, is also
described.
In the past 6-7 years, there have been significant advances
in the chemistry of imido systems involving either antimony1-3
or tellurium.4 The tellurium diimide dimer tBuNTe(µ-NtBu)2-
TeNtBu (1) exists as the cis(endo,endo) isomer in the solid
state,5 although other isomers, for example, trans(exo,exo),
are formed in complexes with metals.6 The dimer 1 reacts
t
readily with heteroallenes, for example, BuNCO, via a
cycloaddition process that generates the ureato telluroxide
[OC(µ-NtBu)2TeO]2.7 The dimer ClSb(µ-NtBu)2SbCl (2) was
reported more than 20 years ago.8 Although the structure of
2 has not been established, Stahl et al. have recently shown
that the derivatives XSb(µ-NtBu)2SbX (X ) OtBu, N3),
prepared by nucleophilic substitution reactions of 2, adopt
trans structures in the solid state.9
Experimental Section
The reagents tBuNTe(µ-NtBu)2TeNtBu (1),10 {Li2[Te(NtBu)3]}2,11
and ClSb(µ-NtBu)2SbCl (2)12 were prepared by the literature
procedures, and their purity was ascertained by 1H NMR spectros-
copy. An improved synthesis of the latter reagent has been described
recently.9 SbCl3 (99.9%), Me3SiN(H)tBu (98%), BuNH2 (98%),
t
and nBuLi (2.5 M solution in hexanes) were obtained from Aldrich.
tBuNH2 and all solvents were dried with appropriate drying agents
and distilled onto molecular sieves before use. All reactions were
carried out under an argon atmosphere using standard Schlenk
techniques or a drybox.
1H NMR spectra were recorded on Bruker AC200 and AMX300
spectrometers, and chemical shifts are reported relative to Me4Si
in CDCl3. 13C and 125Te spectra were measured at 25 °C in C6D6
or C4D8O on a Bruker AMX300 spectrometer using a 5 mm
broadband probe (BBI) operating at 75.448 and 94.817 MHz,
respectively. The spectral widths were 18.115 (13C) and 98.039 kHz
Apart from the aforementioned investigation,9 we are not
aware of other reports of the reactions of 2. In connection
* Author to whom correspondence should be addressed. E-mail: chivers@
ucalgary.ca. Telephone: (403) 220-5741. Fax: (403) 289-9488.
(1) For recent reviews, see: (a) Beswick, M. A.; Mosquera, M. E. G.;
Wright, D. S. J. Chem. Soc., Dalton Trans. 1998, 2437. (b) Beswick,
M. A.; Wright, D. S. Coord. Chem. ReV. 1998, 176, 373.
(2) Bashall, A.; Beswick, M. A.; Feeder, N.; Hopkins, A. D.; Kidd, S. J.;
McPartlin, M.; Raithby, P. R.; Wright, D. J. Chem. Soc., Dalton Trans.
2000, 1841 and references therein.
(3) Bryant, R.; James, S. C.; Jeffery, J. C.; Norman, N. C.; Orpen, A. G.;
Weckenmann, U. J. Chem. Soc., Dalton Trans. 2000, 4007 and
references therein.
(4) (a) For a summary, see: Chivers, T.; Gao, X.; Sandblom, N.; Schatte,
G. Phosphorus, Sulfur Silicon Relat. Elem. 1998, 136-138, 11. (b)
Chivers, T.; Parvez, M.; Schatte, G. Inorg. Chem. 2001, 40, 540 and
references therein.
(
125Te) yielding the respective resolutions of 0.55 and 0.75 Hz/
data point. The values for the 90° pulse widths (pw) were 7.80
(13C) and 15.00 µs (125Te). For the actual acquisitions, nuclear tip
angles of 30° were used [pw(30°, 13C), 2.57 µs; pw(30°,125Te), 4.9
µs]. Relaxation delays of 3 and 1.5 s were applied when measuring
the 13C and 125Te NMR spectra, respectively. The samples for 125Te
NMR were externally referenced to K2TeO3 in D2O and referred
to Me2Te. Line-broadening parameters, used in the exponential
multiplication of the free induction decays, were 10 to 1 Hz.
Chemical shifts with a positive sign are correlated with shifts to
high frequencies (downfield) of the reference compound. Elemental
analyses were performed by Analytical Services, Chemistry Depart-
ment, University of Calgary.
(5) Chivers, T.; Gao, X.; Parvez, M. J. Am. Chem. Soc. 1995, 117, 2359.
(6) (a) Chivers, T.; Parvez, M.; Schatte, G. Angew. Chem., Int. Ed. 1999,
38, 2217. (b) Chivers, T.; Parvez, M.; Schatte, G. Inorg. Chem. 1999,
38, 5171.
(7) Schatte, G.; Chivers, T.; Jaska, C.; Sandblom, N. Chem. Commun.
2000, 1657.
(8) Kuhn, N.; Scherer, O. J. Z. Naturforsch. 1979, 34b, 888.
(9) Haagenson, D. C.; Stahl, L.; Staples, R. J. Inorg. Chem. 2001, 40,
4491.
(10) Chivers, T.; Enright, G. D.; Sandblom, N.; Schatte, G.; Parvez, M.
Inorg. Chem. 1999, 38, 5431.
(11) Chivers, T.; Gao, X.; Parvez, M. Angew. Chem., Int. Ed. Engl. 1995,
34, 2549.
(12) Kuhn, N.; Scherer, O. J. Z. Naturforsch. 1979, 34b, 888.
1002 Inorganic Chemistry, Vol. 41, No. 4, 2002
10.1021/ic0109694 CCC: $22.00 © 2002 American Chemical Society
Published on Web 01/22/2002

NOTE
Synthesis of {[tBuNSb(µ-NtBu)2TeNtBu](µ3-SbCl)}+Cl- (3).
(a) From the Reaction of tBuNTe(µ-NtBu)2TeNtBu and ClSb(µ-
NtBu)2SbCl. A red solution of 1 (0.300 g, 0.556 mmol) in toluene
(10 mL) was added to a stirred pale yellow solution of 2 (0.508 g,
1.112 mmol) in toluene (15 mL) cooled to -78 °C. The resulting
orange solution containing a yellow precipitate was warmed to 23
°C after 30 min to give a yellow-orange solution. After 5 h, the
volatile materials were removed under vacuum. The pale orange
solid was dissolved in THF (10 mL), and then n-pentane (5 mL)
was added whereupon a yellow-orange precipitate of {[tBuNSb(µ-
NtBu)2TeNtBu](µ3-SbCl)}+Cl- (3) (0.333 g, 0.458 mmol; 41%) was
formed. X-ray quality crystals of 3 were obtained by overlaying a
pale yellow solution of 2 (0.127 g, 0.120 mmol) in toluene (∼3
mL) with an orange-red solution of Te2(NtBu)4 (0.075 g, 0.132
mmol) in n-hexane (∼3 mL) in a test tube. Yellow and orange
crystals were formed after 1 d at 23 °C. The orange crystals were
Table 1. Crystallographic Data for 3 and 4‚C7H8
3
4‚C7H8
empirical formula
fw
C16H36Cl2N4Sb2Te
726.49
C19H36N3Cl2SbTe
626.76
P21/n
space group
T (°C)
a, Å
b, Å
c, Å
P21/c
-80
-80
16.150(2)
9.4959(14)
17.035(2)
109.395(3)
2464.2(6)
4
13.9127(17)
11.7159(14)
15.8789(19)
99.693(2)
2551.3(5)
4
1.632
0.71073
24.20
â, deg
V, Å3
Z
F, g cm -3
λ, Å
1.958
0.71073
35.78
0.0301
0.0831
µ, cm-1
R1a
0.0556
0.1579
wR2b (all data)
a R1 ) [∑||Fo|-|Fc||]/[∑|Fo|] for [Fo > 2σ (Fo )]. b wR2 ) {[∑w-
2
2
1
(Fo -Fc )2]/[∑w(Fo )2]}1/2 (all data).
2
2
2
identified as 3. H NMR [in C4D8O at 23 °C]: δ ) 1.639/1.629
[C(CH3)3, 36 H, ∼3:1 intensity ratio]. 13C NMR [in C4D8O at 23
°C]: δ ) 62.12 and 61.06 [C(CH3)3], 35.77 and 33.11 [C(CH3)3].
125Te NMR [in C4D8O at 23 °C]: δ ) 1637. Anal. Calcd for 3: C,
26.45; H, 4.99; N, 7.12. Found: C, 24.89; H, 5.16; N, 6.91. The
yellow crystals were identified as Cl2Te(µ-NtBu)2Sb[N(H)tBu]‚C7H8
(4‚C7H8). 1H NMR (in C6D6 at 23 °C): δ ) 4.6 [s, NH, 1 H], 1.40
[s, C(CH3)3, 18 H], 0.73 [s, C(CH3)3, 9 H]. 1H NMR (in C4D8O at
23 °C): δ ) 6.5 [s, NH, 1 H], 1.50 [s, C(CH3)3, 18 H], 1.41 [s,
C(CH3)3, 9 H], in addition to resonances attributable to toluene
present in the lattice. 125Te NMR (in C4D8O at 23 °C): δ ) 1654.
(b) From the Reaction of SbCl3 and {Li2[Te(NtBu)3]}2. A
solution of SbCl3 (0.321 g, 1.409 mmol) in toluene (10 mL) was
added dropwise with stirring to a pale yellow solution of
{Li2[Te(NtBu)3]}2 (0.500 g, 0.704 mmol) in toluene (15 mL) at
-78 °C. The reaction mixture was allowed to warm slowly to 23
°C and then filtered through a fine frit to remove LiCl and other
insoluble products (0.275 g). Removal of solvent from the filtrate
under vacuum gave a yellow-orange solid (0.510 g) which was
extracted with n-hexane (13 mL) to give Li{Sb[Te(NtBu)3]2} (0.120
parts were refined by constraining the thermal parameters of atoms
in A to be equal to their counterparts in B. However, the positions
of all the atoms were allowed to refine independently. The Cl-
anion is not affected by the disorder. The non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were included at geo-
metrically idealized positions and were not refined. The isotropic
thermal parameters of the hydrogen atoms were fixed at 1.5 times
that of the attached carbon or nitrogen atom.
A yellow platelike crystal of 4‚C7H8 (0.47 × 0.30 × 0.12 mm3)
was coated with Paratone oil and mounted on a glass fiber. Using
φ and ω scans of 0.3° per frame for 15 s, 9674 reflections were
collected of which 3630 were unique (Rint ) 0.0450) and 2782
observed [I g 2σ(I)]. Structure solution and refinement were as
described for 3 with the exception that the isotropic thermal
parameters of the hydrogen atoms were fixed at 1.2 times that of
the corresponding carbon or nitrogen atom. The atoms Sb(1) and
N(3) were disordered over two sites with partial occupancy factors
of 0.5159(17) and 0.4841(17). The atoms in the toluene molecule
were restrained to be coplanar, and the C-C bond distances on
opposite sides of the ring were restrained to be equal.
1
g, 0.148 mmol, 11%) as the soluble product (characterized by H
NMR).13 The yellow hexane-insoluble product was identified by
1H NMR as 3 (0.310 g, 0.404 mmol, 57%) contaminated with small
amounts of 4.
Crystallographic data for 3 and 4‚C7H8 are summarized in
Table 1.
X-ray Crystallography. Intensity data for 3 and 4‚C7H8 were
collected on a Bruker AXS SMART 1000 CCD diffractometer.
An orange crystal of 3 (0.40 × 0.22 × 0.06 mm3) was coated in
Paratone oil and mounted on a glass fiber. Using φ and ω scans of
0.3° per frame and exposure times of 20 s, a total of 13576
reflections were collected and then merged to provide 4994 data,
of which 4692 were unique (Rint ) 0.0448) and 4180 observed
[I > 2σ(I)]. The ranges of indices were -19 e h e 18, 0 e k e
11, and 0 e l e 20, corresponding to 2.49 e θ e 25.81°. A final
difference map revealed no features greater than 0.872 or less than
-1.139 e Å-3. An empirical absorption correction was applied.14
The structure was solved by using direct methods15 and refined by
full-matrix least-squares method on F2.16 The asymmetric unit is
composed of a disordered {[tBuNSb(µ-NtBu)2TeNtBu](µ3-SbCl)}+
cation with site occupancy factors of 0.779(2) and 0.221(2)
represented by cations A and B, respectively. The two disordered
Results and Discussion
The reaction of 1 and 2 in toluene at 23 °C produced a
moisture-sensitive yellow-orange solid identified as the
tricyclic antimony-tellurium imido complex {[tBuNSb(µ-
NtBu)2TeNtBu](µ3-SbCl)}+Cl- (3) by X-ray analysis (vide
1
infra). The H and 13C NMR spectra of 3 in d8-THF at 23
°C show only two NtBu environments, with an intensity ratio
of 1:3, throughout the temperature range 233-300 K. During
the crystallization process, a minor product, also character-
ized by X-ray analysis (vide infra), as Cl2Te(µ-NtBu)2Sb-
[N(H)tBu], was isolated. The 1H NMR spectra of 4 in either
d6-benzene or d8-THF at 23 °C showed two resonances for
NtBu groups, with relative intensities 2:1, in addition to a
broad resonance at δ 4.6 (C6D6) or δ 6.5 (C4D8O) attributable
to an NH group.
(13) Chivers, T.; Parvez, M.; Schatte, G.; Yap, G. P. A. Inorg. Chem. 1999,
38, 1380.
(14) SADABS, V 5.0, Software for Area-Detector Absorption Corrections;
Bruker AXS, Inc.: Madison, WI, 1998.
(15) Sheldrick, G. M. SHELXS-97, Program for the Solution of Crystal
Structures; Universita¨t of Go¨ttingen: Go¨ttingen, Germany 1997.
(16) Sheldrick, G. M. SHELXL-97-2, Program for the Solution of Crystal
Structures; Universita¨t of Go¨ttingen: Go¨ttingen, Germany 1997.
The tricyclic complex 3 was also obtained as the major
product (57%) from the reaction of SbCl3 with {Li2[Te(N-
tBu)3]}2 in a 2:1 molar ratio in toluene. The minor product
from this reaction was identified by 1H NMR as the
spirocyclic complex Li{Sb[Te(NtBu)3]2}, which is obtained
Inorganic Chemistry, Vol. 41, No. 4, 2002 1003

NOTE
t
Figure 1. Thermal ellipsoid (30% probability) plot and atomic numbering scheme for 3 (A+Cl- and B+Cl-). Only the R-carbon atoms of Bu groups are
shown.
in optimum yields (57%) when the same reaction is carried
out in a 1:1 molar ratio.13
The structure of 3 was determined by X-ray crystal-
lography. The unit cell contains disordered {[tBuNSb(µ-
NtBu)2TeNtBu](µ3-SbCl)}+ cations with approximate occu-
pancy factors of 78% and 22% (represented by A and B),
respectively, and Cl- anions (see Figures 1 and 2). As
indicated in Table 2, the Sb(2)-Cl(1) bond lengths in A and
B are 2.547(4) and 2.493(13) Å, and the associated Sb(2)-
N(1) distances are 2.440(4) and 2.462(13) Å (sum of covalent
radii for Sb and Cl ) 2.35 Å and for Sb and N ) 2.06 Å).17
For comparison, the related tricyclic compounds [tBuNP(µ-
t
NR)2PNtBu](µ3-SbCl) (R ) Bu,18 Ph)19 have d(Sb-Cl) )
2.492(3) and 2.439(1) Å, respectively. Stahl and co-workers
1
have shown by VT H NMR studies that complexes of the
type [RNP(µ-NR)2PNR](µ3-ECl) (where E ) Sb, Bi) undergo
an intramolecular pyramidal inversion process in solution
(see Scheme 1).19 The two forms of 3 (A and B) present in
the crystal lattice are optical isomers related by pyramidal
inversion at the Sb(2) center.
The related tricyclic complex SeSb2Cl2(NtBu)4 (5), the
selenium analogue of 3, was prepared by the reaction of the
selenium(II) reagent Se[NtBu(SiMe3)]2 with SbCl3.20,21 The
Figure 2. Unit cell of 3 (A+Cl-) viewed down the b-axis showing the
Te‚‚‚Cl interactions.
major difference between the structures of the isovalent
(17) Alcock, N. W. AdV. Inorg. Chem. Radiochem. 1972, 15, 1.
congeners 3 and 5 involves the location of one of the chlorine
atoms. The selenium complex 5 contains two Sb-Cl bonds
(18) Scherer, O. J.; Wolmersha¨user, G.; Conrad, H. Angew. Chem. Int. Ed.
Engl. 1983, 22, 404.
(19) Moser, D. F.; Schranz, I.; Gerrety, M. C.; Stahl, L.; Staples, R. J. J.
Chem. Soc., Dalton Trans. 1999, 751.
(20) Bjo¨rgvinsson, M.; Roesky, H. W.; Pauer, F.; Sheldrick, G. M. Chem.
[|d(Sb-Cl)| ) 2.581(1) Å], whereas the tellurium complex
3 has only one Sb-Cl bond [2.547(4) Å in cation A] and a
Ber. 1992, 125, 767.
Cl- counterion, which engages in weak interactions with the
1004 Inorganic Chemistry, Vol. 41, No. 4, 2002

NOTE
Table 2. Selected Bond Distances (Å) and Bond Angles (deg) in 3
cation A
cation B
Bond Distances
2.098(7)
1.974(7)
1.991(5)
2.073(6)
2.046(6)
2.014(6)
2.440(4)
2.087(6)
2.072(8)
2.547(4)
Te(1)-N(1)
Te(1)-N(2)
Te(1)-N(3)
Sb(1)-N(1)
Sb(1)-N(2)
Sb(1)-N(4)
Sb(2)-N(1)
Sb(2)-N(3)
Sb(2)-N(4)
Sb(2)-Cl(1)
2.076(19)
1.987(19)
1.993(15)
2.113(17)
2.030(17)
1.993(14)
2.462(13)
2.081(16)
2.085(17)
2.493(13)
Te(1)‚‚‚Cl(2)
3.307(6)
3.198(5)
3.055(22)
3.196(18)
Te(1)‚‚‚Cl(2)* a
Bond Angles
78.1(2)
N(2)-Te(1)-N(1)
N(2)-Te(1)-N(3)
N(3)-Te(1)-N(1)
N(4)-Sb(1)-N(1)
N(4)-Sb(1)-N(2)
N(2)-Sb(1)-N(1)
Sb(1)-N(1)-Te(1)
Sb(1)-N(1)-Sb(2)
Te(1)-N(1)-Sb(2)
Te(1)-N(2)-Sb(1)
N(3)-Sb(2)-N(1)
N(4)-Sb(2)-N(1)
N(4)-Sb(2)-N(3)
N(1)-Sb(2)-Cl(1)
N(3)-Sb(2)-Cl(1)
N(4)-Sb(2)-Cl(1)
Te(1)-N(3)-Sb(2)
Sb(1)-N(4)-Sb(2)
78.3(6)
99.1(12)
82.7(9)
82.7(8)
99.6(11)
76.5(6)
99.6(8)
93.3(6)
94.1(7)
105.6(9)
72.1(6)
72.8(6)
108.6(11)
155.1(5)
94.9(8)
92.4(8)
109.7(8)
109.7(8)
101.0(3)
81.3(3)
82.4(3)
96.4(2)
77.05(19)
99.7(3)
94.8(2)
94.5(2)
104.9(3)
71.62(19)
72.78(19)
109.3(2)
154.33(13)
92.50(19)
94.8(2)
Figure 3. Thermal ellipsoid (30% probability) plot and atomic numbering
scheme for 4.
110.0(3)
109.2(3)
a Symmetry transformations used to generate equivalent atoms. Asterisk
indicates: -x + 1, -y + 1, -z + 1.
Scheme 1. Pyramidal Inversion in the Tricyclic Complexes
[RNP(µ-NR)2PR](µ-ECl) (E ) Sb, Bi)
Figure 4. Unit cell of 4‚C7H8 viewed down the c-axis showing the Sb‚‚‚Cl
interactions. Only molecule A is shown.
Te centers of two cations to form an asymmetric dimeric
structure (Figure 2). The mean Te‚‚‚Cl distances are ∼3.05
and 3.20 Å (cf., sum of van der Waals radii for Te and Cl
of 3.81 Å17 and 4.0 Å22). As a consequence of this ionization,
there is a pronounced asymmetry in the Sb-N bonds
involving the four-coordinate nitrogen atom, N(1), in 3
[2.073(6) and 2.440(4) Å in cation A, cf., 2.298(3) and
2.311(3) Å for the corresponding bond lengths in 520]. The
1H NMR spectrum of 5 in CCl4 shows three resonances for
NtBu groups with relative intensities 1:1:2, consistent with
the solid-state structure.20 By contrast, four equally intense
resonances are anticipated if the solid-state structure of 3
persists in solution. The observation of only two resonances
in a 1:3 ratio (vide supra) suggests a more symmetrical
structure for 3 in solution, possibly similar to that of 5, with
the overlap of the resonance for the two equivalent NtBu
groups with that of one of the unique NtBu groups.
The identity of the minor product from the reaction of 1
and 2 was determined by X-ray analysis to be Cl2Te(µ-
NtBu)2Sb[N(H)tBu] (4), which involves chelation of the
2+
dianionic ligand [tBuN(H)Sb(NtBu)2]2- to a TeCl2 unit.
Related bis-imido complexes of tellurium dichloride are
either monomeric [(Ph3PN)2TeCl223 and (Ph2CN)2TeCl224] or
dimeric [(Me3PN)2TeCl225], or they form extended networks
(21) The tricyclic imido-antimony complex [tBuNSb(µ-NtBu)2SbNtBu](µ3-
SbCl) (7) has been depicted to be isostructural with the cation in 3,
with which it is also isoelectronic, in a conference proceedings.
Complex 7 is described as one of the products of SbCl3 and tBuNH2,
but full details of the synthesis and X-ray structure have not been
reported. Veith, M.; Rammo, A.; Hans, M. Phosphorus, Sulfur Silicon
Relat. Elem. 1994, 93-94, 197.
(23) Roesky, H. W.; Mu¨nzeberg, J.; Bohra, R.; Noltemeyer, M. J.
Organomet. Chem. 1991, 418, 339.
(24) Mu¨nzeberg, J.; Roesky, H. W.; Noltemeyer, M.; Besser, S.; Herbst-
Irmer, R. Z. Naturforsch. B: Chem. Sci. 1993, B48, 199.
(25) Folkerts, H.; Dehnicke, K.; Magull, J. Z. Naturforsch., B: Chem. Sci.
1995, 50b, 573.
(22) Pauling, L. The Nature of the Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1960; Chapter 7, p 260.
Inorganic Chemistry, Vol. 41, No. 4, 2002 1005

NOTE
Table 3. Selected Bond Distances (Å) and Bond Angles (deg)
in 4‚C7H8
[172.29(9)°] (Table 3). The almost equal Te-Cl bond
distances [2.657(3)-2.695(3) Å] are at the high end of the
range of values found for Te-Cl bonds in related com-
plexes,10,23-27 presumably as a result of the Sb‚‚‚Cl interac-
tions. Interestingly, the average Sb-N bond length in 4
(1.957 Å) is ∼0.09 Å shorter than that in related com-
pounds.29 On the other hand, the average Te-N bond length
of 2.072 Å in 4 is significantly longer than the corresponding
value of 1.998 Å in PhB(µ-NtBu)2TeCl2, which has a dimeric
structure.30
Molecule A
Molecule B
Bond Distances
1.963(7)
Sb(1)-N(2)
Sb(1′)-N(3′)
1.901(18)
1.958(7)
1.968(7)
Sb(1)-N(3)
Sb(1)-N(1)
Te(1)-N(1)
Te(1)-N(2)
Te(1)-Cl(1)
Te(1)-Cl(2)
Sb(1)‚‚‚C1(2)
Sb(1)‚‚‚C1(1)* a
1.969(15)
1.983(7)
2.051(7)
2.093(7)
2.657(3)
2.695(3)
3.290(3)
3.453(3)
Sb(1′)-N(1)
Sb(1′)-N(2)
Sb(1′)‚‚‚C1(1)
C1(2)‚‚‚Sb(1′)*
3.314(3)
3.442(3)
Complex 3 can be viewed as the result of the cycloaddition
of a tellurium diimide monomer tBuNTeNtBu to dimer 2 (and
ionization of one Sb-Cl bond). The formation of 4 is
puzzling, but the presence of the tBuNH substituent implies
that tBuNH2, generated by hydrolysis, is involved. It is also
significant that 4 is formed by both synthetic methods [(a)
and (b)], implying that a common intermediate, for example,
tBuNTe(µ-NtBu)2SbCl (6), may be involved. Complex 6 can
be viewed as (a) the cycloaddition product of two monomeric
Bond Angles
N(2)-Sb(1)-N(3)
N(2)-Sb(1)-N(1)
N(3)-Sb(1)-N(1)
Sb(1)-N(1)-Te(1)
Sb(1)-N(2)-Te(1)
N(1)-Te(1)-N(2)
N(1)-Te(1)-Cl(1)
N(2)-Te(1)-Cl(1)
N(1)-Te(1)-Cl(2)
N(2)-Te(1)-Cl(2)
Cl(1)-Te(1)-Cl(2)
100.3(6)
79.1(3)
97.7(5)
97.0(3)
96.2(3)
74.6(3)
86.7(2)
91.0(2)
86.0(2)
89.2(2)
172.29(9)
N(3′)-Sb(1′)-N(1)
N(1)-Sb(1′)-N(2)
N(3′)-Sb(1′)-N(2)
Sb(1′)-N(1)-Te(1)
Sb(1′)-N(2)-Te(1)
102.2(6)
79.6(3)
99.8(6)
96.9(3)
95.3(3)
t
t
units, BuNTeNtBu and BuNSbCl, or (b) the metathesis
product from the 1:1 reaction of [Te(NtBu)3]2- with SbCl3.
Further reaction of 6 with Li2[Te(NtBu)3] would give
Li{Sb[Te(NtBu)3]2}, the minor product of synthesis (b).
a Symmetry transformations used to generate equivalent atoms. Asterisk
indicates: -x + 1.5, y + 0.5, -z + 0.5.
Acknowledgment. We thank NSERC (Canada) for
financial support, Dr. R. McDonald (University of Alberta)
for the X-ray data collections, and Prof. G. M. Sheldrick
(Universita¨t Go¨ttingen) for helpful discussions.
through weak Te‚‚‚Cl interactions [MeN[PhBN(Me)]2Te-
Cl2,26 (Ph2SN)2TeCl2,24 [(Me3Si)2N]2TeCl2,27 and [Cl2Te(µ-
NtBu)2TeCl2]10]. Complex 4 also forms an extended structure
(Figure 4), but in this case, the weak intermolecular interac-
tions involve Sb‚‚‚Cl, rather than Te‚‚‚Cl, contacts in the
range 3.290(3)-3.453(3) Å (cf., sum of van der Waals radii
for Sb and Cl ) 3.80 Å17 or 4.0 Å22). Both of the Sb sites
in the disordered molecules of 4 participate in these interac-
tions.28 The influence of the lone pair on tellurium is evident
from the deviation from linearity of the ClTeCl unit
Supporting Information Available: The X-ray crystallographic
files, in CIF format. This material is available free of charge via
the Internet at http://pubs.acs.org.
IC0109694
(28) In one molecule, the Sb(1) atom lies 0.879(9) Å above and the N(3)
atom is 0.463(21) Å below the N(2)Te(1)N(1) plane. In the second
molecule, the Sb(1′) atom lies 0.887(9) Å below and the N(3′) atom
is 0.324(22) Å above that plane.
(26) Koch, H.-J.; Roesky, H. W.; Besser, S.; Herbst-Irmer, R. Chem. Ber.
1993, 126, 571.
(29) An average value of 2.050 Å is cited in ref 9 for Sb-N bonds in
(27) Pietika¨inen, J.; Laitinen, R. S.; Valkonen, J. Acta Chem. Scand. 1999,
53, 963.
related antimony-nitrogen heterocycles.
(30) Chivers, T.; Schatte, G. Unpublished results.
1006 Inorganic Chemistry, Vol. 41, No. 4, 2002