Dimethyltellurium(IV) derivatives with mixed 1,1-dithio ligands. Crystal structures of Me2Te[S2CNMe2][S2COEt] and Me2Te[S2CNEt2][S2COMe]

Article abstract of DOI:10.1139/v99-123

Mixed ligand derivatives of Me₂TeLL′₂, where L = N,N-dialkyl dithiocarbamate or O,O-alkylene dithiophosphate and L′ = O-alkyl dithiocarbonate, have been synthesized and characterized by elemental analysis, ¹H, ¹³C, ³¹P, and ¹²⁵Te NMR spectroscopy and infrared and Raman spectroscopy, and X-ray crystallography. Me₂Te[S₂CNMe₂][S₂COEt], 8: P1 (no. 2), with cell parameters a = 10.073(3) A, b = 10.139(2) A, c = 9.108(2) A, α = 92.36(2)°, β = 115.55(2)°, γ = 111.19(2)°, V = 760.7(4) A³, Z = 2, R = 0.0343, R_w = 0.0296. Me₂Te[S₂CNEt₂][S₂COMe], 9: P2₁/c (no. 14) with cell parameters a = 9.881(4) A, b = 17.671(3) A, c = 10.149(4) A, β = 113.65(3)°, V = 1623.3(10) A³, Z = 4, R = 0.0567, R_w = 0.0514. The immediate environment about tellurium in both molecules is essentially that of a saw-horse structure in which the lone pair is apparently stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. The S-Te-S angles in the two molecules are 166.87(6)° and 162.0(1)° for 8 and 9, respectively. In both molecules, the Te - S bonds to the dithiocarbamate groups are slightly shorter than those to dithiocarbonates. The dithiocarbamate groups are oriented to give secondary interactions involving the apparently terminal sulfur atoms resulting in Te - S distances of 3.205(2) and 3.277(4) A, respectively, in 8 and 9. However, only in 9 is there a similar Te - S distance of 3.346(5) A involving the S₂COMe group because in 8, the OEt group of S₂COEt, rather than the terminal S atom, is oriented toward Te.

Full text of DOI:10.1139/v99-123

1262
Dimethyltellurium(IV) derivatives with mixed
1,1-dithio ligands. Crystal structures of
Me2Te[S2CNMe2][S2COEt] and
Me2Te[S2CNEt2][S2COMe]
John E. Drake, Layla N. Khasrou, Anil G. Mislankar, and Raju Ratnani
Abstract: Mixed ligand derivatives of Me2TeLL′2, where L = N,N-dialkyl dithiocarbamate or O,O-alkylene
dithiophosphate and L′ = O-alkyl dithiocarbonate, have been synthesized and characterized by elemental analysis,
1H, 13C, 31P, and 125Te NMR spectroscopy and infrared and Raman spectroscopy, and X-ray crystallography.
Me2Te[S2CNMe2][S2COEt], 8: P1 (no. 2), with cell parameters a = 10.073(3) Å, b = 10.139(2) Å, c = 9.108(2) Å,
α = 92.36(2)°, β = 115.55(2)°, γ = 111.19(2)°, V = 760.7(4) Å3, Z = 2, R = 0.0343, Rw = 0.0296.
Me2Te[S2CNEt2][S2COMe], 9: P21/c (no. 14) with cell parameters a = 9.881(4) Å, b = 17.671(3) Å, c = 10.149(4) Å,
β = 113.65(3)°, V = 1623.3(10) Å3, Z = 4, R = 0.0567, Rw = 0.0514. The immediate environment about tellurium in
both molecules is essentially that of a saw-horse structure in which the lone pair is apparently stereochemically active
and occupying an equatorial position in a distorted trigonal bipyramid. The S-Te-S angles in the two molecules are
166.87(6)° and 162.0(1)° for 8 and 9, respectively. In both molecules, the Te—S bonds to the dithiocarbamate groups
are slightly shorter than those to dithiocarbonates. The dithiocarbamate groups are oriented to give secondary
interactions involving the apparently terminal sulfur atoms resulting in Te—S distances of 3.205(2) and 3.277(4) Å,
respectively, in 8 and 9. However, only in 9 is there a similar Te—S distance of 3.346(5) Å involving the S2COMe
group because in 8, the OEt group of S2COEt, rather than the terminal S atom, is oriented toward Te.
Key words: structure, tellurium, methyl, dithiocarbamates, dithiocarbonates, dithiophosphates.
Résumé : On a synthétisé des dérivés à ligands mixtes du Me2TeLL′2 dans lesquels L = dithiocarbamate de N,N-
dialkyle ou dithiophosphate de O,O-alkylène et L′ = dithiocarbonate de O-alkyle et on les a caractérisés par analyse
1
élémentaire, spectroscopie RMN du H, 13C, 31P et 125Te, spectroscopie infrarouge et Raman et par diffraction des
rayons X. Me2Te[S2CNMe2][S2COEt], 8, P1 (no. 2), avec a = 10,073(3), b = 10,139(2) et c = 9,108(2) Å, α =
92,36(2), β = 115,55(2) et γ = 111,19(2)°, V = 760,7(4) Å3, Z = 2, R = 0,0343, Rw = 0,0296.
Me2Te[S2CNEt2][S2COMe], 9, P21/c (no. 14), avec a = 9,881(4), b = 17,671(3) et c = 10,149(4) Å, β = 113,65(3)°, V
= 1623,3(10) Å3, Z = 4, R = 0,0567, Rw = 0,0514. Dans les deux molécules, l’environnement immédiat autour du
tellure est essentiellement celui d’une structure cavalière dans laquelle la paire d’électrons libres est apparemment
stéréochimiquement active et elle occupe une position équatoriale dans une bipyramide trigonale déformée. Dans les
deux molécules, les angles S-Te-S sont de 166,87(6) et 162,0(1)° pour les molécules 8 et 9 respectivement. Dans
chacune des molécules, les liaisons Te—S vers les groupes dithiocarbamates sont légèrement plus courtes que celles
dans les dithiocarbonates. Les groupes dithiocarbonates sont orientés de façon à donner des interactions secondaires
impliquant les atomes de soufre apparemment terminaux; il en résulte des distances Te—S de 3,205(2) et 3,277(4) Å
pour les composés 8 et 9 respectivement. Toutefois, seul le composé 9 donne lieu à une distance Te—S semblable,
3,346(5) Å, impliquant le groupe S2COMe; cette situation résulte du fait que, dans le composé 8, c’est le groupe OEt
du S2COEt qui est orienté vers le Te et non l’atome S terminal.
Mots clés : structure, tellure, méthyle, dithiocarbamates, dithiocarbamates, dithiophosphonates.
[Traduit par la Rédaction] Drake et al. 1273
Introduction
O-alkyl dithiocarbonates (1–6), N,N-dialkyl dithiocarbamates
(5–14), and O,O-dialkyl (alkylene) dithiophosphates (4–6,
13–20), but relatively few refer to the formation of
mixed ligand moieties, such as those of the general type
Several reports have appeared on organotellurium(IV)
compounds with a variety of 1,1-dithio ligands including
Received February 3, 1999.
J.E. Drake1 and L.N. Khasrou. Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada.
A.G. Mislankar. Information Technology, Celestica Inc., 844 Don Mills Road, Toronto, ON M3C 1V7, Canada.
R. Ratnani. Department of Applied Chemistry and Chemical Technology, M.D.S. University, Ajmer, India.
1Author to whom correspondence may be addressed. Telephone: (519) 253-4232. Fax: (519) 973-7098. e-mail: ak4@uwindsor.ca
Can. J. Chem. 77: 1262–1273 (1999)
© 1999 NRC Canada

Drake et al.
1263
RTeL2L′ (14) or R2TeLL′ (21). We report on the synthesis of
ies were obtained for compounds 1–4 despite extensive
efforts at recrystallization.
nine dimethyltellurium(IV) compounds with mixed 1,1-
1
dithio ligands along with their characterization by H, 13C,
31P, and 125Te NMR spectroscopy, infrared and Raman spec-
troscopy, and elemental analysis. X-ray crystal structures of
Me2Te[S2CNMe2][S2COEt], 8, and Me2Te[S2CNEt2][S2COMe],
9, confirm that these are mixed ligand species and not 1:1
mixtures of the bis derivatives.
Preparation of dimethyl(O-alkyl dithiocarbonato)(O,O-
alkylene dithiophosphato)tellurium(IV) compounds
essentially
In a manner
reaction of Me2TeCl[S2POCMe2CMe2O] (0.234 g, 0.58 mmol)
KS2COMe (0.087 g,
the same as described above, the
in dichloromethane (20 mL) with
0.59 mmol) gave Me2Te[S2COMe][S2POCMe2CMe2O], 5,
as pale-yellow crystalline material: 0.223 g, yield 81%, mp
87–88°C. Anal. calcd. for C10H21O3PS4Te: C 25.23, H 4.45;
Experimental
Similarly,
found: C 25.30, H 4.85.
using KS2COEt was formed
Materials
TeCl4, Me4Sn, NaS2CNMe2, and NaS2CNEt2 were ob-
tained from Aldrich, and the latter two were dried in vacuo
for 4–5 days prior to use. Me2TeCl2 was prepared by the re-
action of TeCl4 and Me4Sn in toluene at 60°C under reflux
for 4 h by adaptation of the method used for the preparation
of Ph2TeCl2 (22). Me2TeCl[S2CNMe2] and Me2TeCl[S2CNEt2]
were prepared as described in the literature (12) as were the
sodium and ammonium salts of O,O-alkylene dithiophos-
phatic acids and the potassium salts of O-alkyl dithiocar-
bonic acids (23, 24). All solvents were dried and distilled
prior to use, and all reactions carried out under anhydrous
conditions.
Me2Te[S2COEt][S2POCMe2CMe2O], 6, as pale-yellow crys-
tals: yield 83%, mp 72°C. Anal. calcd. for C11H23O3PS4Te:
C 26.96, H 4.73; found: C 27.07, H 4.83. Unfortunately, at-
tempts to grow X-ray quality crystals of 5 and 6 were not
successful.
Preparation of dimethyl(N,N-dialkyl dithiocarbamato)
(O-alkyl dithiocarbonato)tellurium(IV) compounds
Typically, KS2COMe (0.154 g, 1.05 mmol) was added,
with constant stirring, to a solution of Me2TeCl[S2CNMe2]
(0.324 g. 1.03 mmol) in dichloromethane (20 mL). The col-
orless reaction mixture changed to yellow after a few min-
utes. The stirring was continued for 1 h after which KCl and
unreacted dithiocarbonate salt were filtered off before the
solvent was pumped off under vacuum to yield a yellow
powder. The crude product was recrystallized from dichloro-
methane–n-hexane to give Me2Te[S2CNMe2][S2COMe], 7,
as yellow crystals: 0.176 g, yield 88%, mp 95–97°C. Anal.
calcd. for C7H15NOS4Te: C 21.84, H 3.93; found: C 22.22,
H 3.85. Similarly were obtained Me2Te[S2CNMe2][S2COEt],
8, as yellow crystals: yield 88%, mp 106–108°C. Anal.
calcd. for C8H17NOS4Te: C 24.08, H 4.29; found: C 24.15,
H 4.18. Me2Te[S2CNEt2][S2COMe], 9, as yellow crystals:
yield 89%, mp 75–77°C. Anal. calcd. for C9H19NOS4Te: C
26.17, H 4.62; found: C 25.56, H 4.71. X-ray quality crys-
tals were obtained for compounds 8 and 9, but not for 7 de-
spite extensive attempts at recrystallization.
Preparation of dimethyl(N,N-alkyl dithiocarbamato)(O,O-
alkylene dithiophosphato)tellurium(IV) compounds
Typically, NaS2POCMe2CMe2O (ca. 1.4 mmol) was
added to a solution of an equimolar amount of Me2TeCl2 in
dried dichloromethane (20 mL). The mixture was stirred for
2 h and then filtered to remove NaCl and unreacted dithio-
phosphate salt. The solvent was reduced to 5 mL under vac-
uum, n-hexane (5 mL) was added, and the solution left
overnight in the refrigerator at –6°C. The resulting crystals
were washed with n-hexane and dried in vacuum to give
Me TeCl[S POCMe CMe O
] as white crystals. Me2TeCl-
2
2
2
2
[S2POCMe2CMe2O] (0.470 g, 1.16 mmol) was then dis-
solved in dichloromethane (20 mL), NaS2CNMe2 (0.168 g,
1.17 mmol) added with constant stirring, and the colorless
solution turned yellow. The mixture was stirred for 2 h at
ambient temperature and then filtered to remove NaCl or
any unreacted dithiocarbamate salt. The volume of the sol-
vent was reduced to 5 mL, n-hexane (5 mL) was added, and
the solution was left overnight in the refrigerator at –6°C.
The solvent was decanted off the crystals, which were then
pumped on to dryness on the vacuum line to give
Me2Te[S2CNMe2][S2POCMe2CMe2O], 1, as yellow crystals
(0.459 g, yield 81%; mp 129°C). Anal. calcd. for
C11H24NO2PS4Te: C 27.01, H 4.95; found: C 26.85, H 4.75.
Alternative synthesis of Me2Te
[S2CNMe2][S2POCMe2CMe2O], 1, and compounds 2–6
In essentially
the same manner as described above,
NH4S2POCMe2CMe2O (0.124 g, 0.54 mmol) was added,
with constant stirring, to a solution of Me2TeCl[S2CNMe2]
(0.165 g, 0.53 mmol) in dichloromethane (20 mL). The col-
orless reaction mixture immediately changed to yellow. The
reaction mixture was stirred for 2 h, filtered to remove NH4Cl
or any unreacted dithiophosphate salt, and then n-hexane
(approximately 5 mL) was added after the solvent had been
reduced to 5 mL by pumping. Crystals were formed when
the solution was left overnight in the refrigerator at –6°C.
The solvent was decanted and the crystals pumped to dry-
ness to give Me2Te[S2CNMe2][S2POCMe2CMe2O], 1, as
yellow crystals: 0.218 g, yield 85%, mp 129°C. Similarly
were formed compounds 2–6.
Similarly, using
NaS2CNEt2 was formed Me2Te[S2CNEt2]
[S2POCMe2CMe2O], 2, as yellow crystals (yield 86%, mp
127–128°C). Anal. calcd. for C13H28NO2PS4Te: C 30.20, H
5.46; found: C 29.74, H 5.28. Similarly, starting with
Me2TeCl[S2POCH2CMe2CH2O] was formed Me2Te-
[S2CNMe2][S2POCH2CMe2CH2O], 3, as yellow crystals
(yield 83%, mp 114–115°C). Anal. calcd. for
C 25.28, H 4.67;
C10H22NO2PS4Te:
found: C 25.58, H 4.54.
Me2Te[S2CNEt2][S2POCH2CMe2CH2O], 4, as yellow crys-
tals (yield 87%, mp 88–89°C). Anal. calcd. for
C12H26NO2PS4Te: C 28.64, H 5.21; found: C 28.43, H 5.27.
Unfortunately, no crystals suitable for X-ray diffraction stud-
Alternative in situ preparation of
Me2Te[S2CNMe2][S2COMe], 7
Typically, NaS2CNMe2 (0.147 g, 1 mmol) was added to a
solution of Me2TeCl2 (0.228 g, 1 mmol) in dried carbon
© 1999 NRC Canada

1264
Can. J. Chem. Vol. 77, 1999
Table 1. Summary of crystal data, intensity collection, and structural refinement for Me2Te[S2CNMe2][S2COEt], 8, and
Me2Te[S2CNEt2][S2COMe], 9.
Parameter
8
9
a, Å
b, Å
c, Å
α, deg
β, deg
γ, deg
V, Å3
Crystal system
Space group
Mol. wt., g mol–1
Z
10.073 (3)
10.139 (2)
9.108 (2)
92.36 (2)
115.55 (2)
111.19 (2)
760.7 (4)
Triclinic
P1 (no. 2)
399.07
9.881 (4)
17.671 (3)
10.149 (4)
90.00
113.65 (3)
90.00
1623.3 (10)
Monoclinic
P21/c (no. 14)
413.10
4
2
Crystal dimensions, mm
ρ (calcd.), g cm–1
µ, cm–1
0.31 × 0.19 × 0.12
1.742
24.66
0.28 × 0.23 × 0.15
1.690
23.3
Transmission factors
Temperature, °C
Radiation, Å
Monochromator
Scan method
Scan speed, °/min
Max. 2θ
0.67–1.00
23
MoKα 0.71069
Highly oriented graphite
ω-2θ
0.62–1.00
23
MoKα 0.71069
Highly oriented graphite
ω-2θ
16.0
50
16.0
50
Total reflections measured
No. of unique data
No. of obsd. data (I > 3.00σ(I))
No. of parameters (NP)
R = Σ1Fo| – |Fc1/Σ|Fo|
2850
2682
1824
136
0.0343
0.0296
1.29
0.001
6052
2207
1339
145
0.0567
0.0514
2.33
0.001
0.72
Te
2
Rw =[(Σw(|Fo| – |Fc|)2/ΣwFo )]1/2
Goodness of fit
Largest shift/esd, final cycle
Largest residual electron density, e Å–3
Atom associated with residual density
0.51
Te
disulfide or dichloromethane (20 mL). The reaction mixture
was stirred for 2 h, and then KS2COMe (0.146 g, 1 mmol)
was added before the mixture was stirred for a further 2 h.
The resulting mixture was filtered to remove NaCl, KCl, and
unreacted materials, and the solvent reduced to 5 mL under
vacuum before n-hexane (5 mL) was added. A yellow pow-
der resulted, which was dried under vacuum after the solvent
was decanted. The compound was recrystallized from di-
choromethane–n-hexane to give Me2Te[S2CNMe2][S2COMe],
7, as yellow crystals: 0.280 g, yield 72%, mp 95–97°C. All
of the compounds 1–9 were also prepared in this manner.
were recorded using samples in sealed capillary tubes on a
Spectra-Physics 164 spectrometer using the 5145 Å exciting
line of an argon ion laser. The melting points were deter-
mined on a Fisher–Johns apparatus.
X-ray crystallographic analysis
Pale yellow block-shaped crystals of Me2Te[S2CNMe2]-
[S2COEt], 8, and Me2Te[S2CNEt2][S2COMe], 9, were sealed
in thin-walled glass capillaries and mounted on a Rigaku
AFC6S diffractometer, with graphite-monochromated MoKα
radiation.
Cell constants corresponded to triclinic and monoclinic
cell for 8 and 9, respectively, whose dimensions are given in
Table 1, along with other experimental parameters. Based on
the appropriate systematic absences for 9, statistical analyses
of intensity distributions, and the successful solution and re-
finement of the structures, the space groups were determined
to be P1 (no. 2) for 8 and P21/c (no. 14) for 9. The data
were corrected for Lorentz and polarization effects, and an
empirical absorption correction was applied.
Physical measurements
Elemental analyses were performed at Guelph Chemical
Laboratories, Guelph, Ontario. The 1H and 13C NMR spectra
were recorded on a Bruker 300 FT/NMR spectrometer in
CDCl3 using Me4Si as internal standard. The 31P and 125Te
NMR spectra were recorded on a Bruker 200 FT/NMR spec-
trometer in CDCl3 using 85% H3PO4 andMe2Te, respec-
tively, as external standard. The infrared spectra were
recorded on a Nicolet 5DX FT spectrometer as KBr pellets
and far infrared spectra on a Bomem IR spectrometer be-
tween polyethylene films as Nujol mulls. Raman spectra
The structures were solved by direct methods (25), and all
calculations were performed using the TEXSAN (26) crys-
tallographic software package of Molecular Structure Corp.2
2
2
2
2 2
2 Least-squares function minimized: Σw(,Fo, – ,Fc,)2, where w = 4Fo (Fo ), σ2(Fo ) = [S2(C + R2B) + (pFo ) ]/(Lp)2, S = scan rate, C = total inte-
grated peak count, R = ratio of scan time to background counting time, Lp = Lorentz-polarization factor, and p = p factor.
© 1999 NRC Canada

Drake et al.
1265
The non-hydrogen atoms were refined anisotropically, and
the hydrogen atoms were included in their idealized posi-
tions with C—H set at 0.95 Å and with isotropic thermal pa-
rameters set at 1.2 times that of the carbon atom to which
they were attached.
The weighted and unweighted agreement factors and stan-
dard deviation of an observation of unit weight3 are given in
Table 1. Plots of Σw(|Fo| – |Fc|)2 versus |Fo|, reflection order
in data collection, sin θ/λ, and various classes of indices
showed no unusual trends. Interatomic distances and bond
angles are given in Table 2, and the molecular structures of
the two compounds are displayed as ORTEP diagrams in
Figs. 1–4. The final atomic coordinates and equivalent iso-
tropic thermal parameters for the non-hydrogen atoms,
anisotropic thermal parameters for non-hydrogen atoms, and
final fractional coordinates and thermal parameters for hy-
drogen atoms, have been deposited.4
[1]
[2]
[3]
Me2TeCl[S2POGO] + NaS2CNR2
→ Me2Te[S2CNR2][S2POGO]
Me2TeCl[S2POCMe2CMe2O] + KS2COR′
→ Me2Te[S2COR′][S2POCMe2CMe2O]
Me2TeCl[S2CNR2] + KS2COR′
→ Me2Te[S2CNR2][S2COR′]
(G = -CMe2CMe2-, -CH2CMe2CH2-; R = Me, Et;
R′ = Me, Et)
These mixed ligand dimethyltellurium(IV) compounds can
also be formed in similar yields by the addition of the am-
monium salt of the dithiophosphoric acid to chlorodimethyl
(N,N-dialkyl dithiocarbamato)tellurium(IV) as exemplified
by eq. [4]:
[4]
Me2TeCl[S2CNMe2] + NH4S2POCMe2CMe2O
Calculation of Pauling partial bond order
The formula proposed by Pauling (27) for calculating the
bond orders of partial bonds is given by dn – d = –0.60 log
n, where dn is the bond length for bond number, n, and d is
the length of the single bond of the same type. Based on the
C—C single bond of 1.54 Å, Pauling’s formula gives bond
lengths of 1.36 Å for n = 2; 1.72 Å for n = 0.5; and 1.90 Å
for n = 0.25. These give percentage increases in bond length
for the partial bonds of approximately 12 and 23%, respec-
tively, for n = 0.5 and 0.25. It is reasonable to assume that
similar relationships relating bond order to interatomic dis-
tances for the much longer secondary interactions or partial
bonds involving Te and S should utilize percentage differ-
ences “normalized” to 1.54 as follows rather than absolute
differences.
→ Me2Te[S2CNMe2][S2POCMe2CMe2O]
The Me2TeClL species can also be prepared in situ in
which case the reaction involves the complete addition of an
equimolar amount of the salt of one 1,1-dithio acid to
dimethyltellurium dichloride, the removal of insoluble salts,
and the addition of an equimolar amount of the salt of a dif-
ferent 1,1-dithio acid, as exemplified by eqs. [5] and [6].
The overall yield based on Me2TeCl2 is close to 70%
[5]
Me2TeCl2 + KS2COR′
→ Me2TeCl[S2COR′] + KCl
Me2TeCl[S2COR′] + NaS2CNR2
→ Me2Te[S2CNR2][S2COR′] + NaCl
[6]
Pauling’s relationship, which can be written as n = 10X,
where X = (d – dn)/0.6, can be modified to allow for percent-
age differences normalized to 1.54 to give X = [1.54(d –
dn)/d]/0.6 or X = 2.5(d - dn)/d. Based on a Te—S single bond
length of 2.63 Å, typical calculated values of the lengths of
partial bonds for various values of n are as follows: 1.0,
2.63; 0.75, 2.76; 0.50, 2.95; 0.25, 3.26; 0.10, 3.68; n, bond
length (Å). This scale appears to be compatible with the sum
of the van der Waals radii of 3.86 Å for Te and S (28).
Solid samples of compounds 1–9 are stable over extended
periods, particularly when stored in the refrigerator, as can
be confirmed by the fact that NMR spectra recorded after
several months show no changes from the spectra recorded
immediately after the formation of the compounds. All of
the compounds are soluble in common organic solvents such
as benzene, toluene, carbon disulfide, dichloromethane, and
chloroform, the later being used as the solvent for spectro-
scopic studies. The vibrational spectra as well as the NMR
spectra of the freshly prepared samples provide definitive
evidence that these compounds are indeed the mixed ligand
species, Me2TeLL′, and not 1:1 mixtures of the bis species
Me2TeL2 and Me2TeL′2. This is of course further confirmed
by the X-ray structures of 8 and 9. The NMR spectra re-
corded over time also indicate that eventually all derivatives,
Me2TeLL′, slowly disproportionate to the two bis deriva-
tives, Me2TeL2 and Me2TeL′2. The three species appear to be
in equilibrium because the addition of more Me2TeL2 to a
solution brings about the expected changes in the relative
Results and discussion
The preparation of a variety of dimethyltellurium(IV)
compounds with two different 1,1 dithio ligands is achieved
in 80–90% yield by the action of approximately equimolar
amounts of the sodium or potassium salt of a dithiocarbamic
or dithiocarbonic acid with an O,O-alkylene dithiophosphate
or N,N-dialkyl dithiocarbamate derivative of chlorodi-
methyltellurium(IV)
such as Me2TeCl[S2POCMe2CMe2O],
Me2TeCl[S2POCH2CMe2CH2O], or Me2TeCl[S2CNMe2] in
dichloromethane, in accord with the eqs. [1]–[3]:
3 Standard deviation of an observation of unit weight: Σw(,Fo, – ,Fc,)2/(No – Nv)1/2, where No = number of observations and Nv = number of
variables.
4 Copies of material deposited may be purchased from: The Depository of Unpublished Data, Document Delivery, CISTI, National Research
Council Canada, Ottawa, Canada, K1A 0S2. Tables of atomic coordinates have also been deposited with the Cambridge Crystallographic
Data Centre and can be obtained on request from: The Director, Cambridge Crystallographic Data Centre, University Chemical Laboratory,
12 Union Road, Cambridge, CB2 1EZ, U.K. Structure factor amplitudes are no longer being deposited and may be obtained directly from
the author.
© 1999 NRC Canada

1266
Can. J. Chem. Vol. 77, 1999
Table 2. Interatomic distances (Å) and angles (deg) for Me2Te[S2CNMe2][S2COEt], 8, and
Me2Te[S2CNEt2][S2COMe], 9.a
Me2Te[S2CNMe2][S2COEt], 8
Te(1)—S(1)
Me2Te[S2CNEt2][S2COMe], 9
2.620(2)
2.650(2)
2.128(6)
2.132(7)
1.762(7)
1.682(7)
1.311(8)
1.435(9)
1.445(9)
1.729(7)
1.633(7)
1.343(8)
1.451(9)
1.46(1)
Te(1)—S(1)
Te(1)—S(3)
Te(1)—C(1)
Te(1)—C(2)
S(1)—C(3)
S(2)—C(3)
N(1)—C(3)
N(1)—C(4)
N(1)—C(6)
S(3)—C(8)
S(4)—C(8)
O(1)—C(8)
O(1)—C(9)
C(4)—C(5)
C(6)—C(7)
S(1)—S(2)
S(3)—S(4)
Te(1)—S(2)
Te(1)—S(4)
Te(1)—O(1)
Te(1)—S(2)1
Te(1)—Te(1)1
2.608(5)
2.620(5)
2.11(1)
2.10(2)
1.75(1)
1.67(2)
1.38(2)
1.46(2)
1.46(2)
1.74(2)
1.66(2)
1.32(2)
1.43(2)
1.51(2)
1.52(2)
2.987(6)
3.007(7)
3.277(4)
3.346(5)
4.64(1)
3.585(5)
4.072(2)
Te(1)—S(3)
Te(1)—C(1)
Te(1)—C(2)
S(1)—C(3)
S(2)—C(3)
N(1)—C(3)
N(1)—C(4)
N(1)—C(5)
S(3)—C(6)
S(4)—C(6)
O(1)—C(6)
O(1)—C(7)
C(7)—C(8)
S(1)—S(2)
S(3)—S(4)
2.994(3)
2.956(3)
3.205(2)
5.085(2)
3.145(5)
3.567(2)
4.0251(9)
Te(1)—S(2)
Te(1)—S(4)
Te(1)—O(1)
Te(1)—S(2)′
Te(1)—Te(1)′
S(1)-Te(1)-S(3)
S(1)-Te(1)-C(1)
S(1)-Te(1)-C(2)
S(3)-Te(1)-C(1)
S(3)-Te(1)-C(2)
C(1)-Te(1)-C(2)
Te(1)-S(1)-C(3)
S(1)-C(3)-S(2)
S(1)-C(3)-N(1)
S(2)-C(3)-N(1)
C(3)-N(1)-C(4)
C(3)-N(1)-C(5)
C(4)-N(1)-C(5)
166.87(6)
S(1)-Te(1)-S(3)
S(1)-Te(1)-C(1)
S(1)-Te(1)-C(2)
S(3)-Te(1)-C(1)
S(3)-Te(1)-C(2)
C(1)-Te(1)-C(2)
Te(1)-S(1)-C(3)
S(1)-C(3)-S(2)
S(1)-C(3)-N(1)
S(2)-C(3)-N(1)
C(3)-N(1)-C(4)
C(3)-N(1)-C(6)
C(4)-N(1)-C(6)
N(1)-C(4)-C(5)
N(1)-C(6)-C(7)
Te(1)-S(3)-C(8)
S(3)-C(8)-S(4)
S(3)-C(8)-O(1)
S(4)-C(8)-O(1)
C(8)-O(1)-C(9)
162.0(2)
87.1(5)
81.3(5)
88.2(5)
82.0(4)
96.4(7)
99.3(6)
122(1)
114(1)
124(1)
124(1)
120(1)
116(1)
115(1)
114(1)
99.6(6)
124(1)
110(1)
126(1)
119(1)
88.5(2)
83.4(2)
87.8(2)
84.4(2)
95.3(3)
98.1(2)
120.8(4)
117.0(5)
122.2(6)
124.9(7)
121.5(7)
113.6(6)
Te(1)-S(3)-C(6)
S(3)-C(6)-S(4)
103.0(3)
123.1(5)
111.9(5)
125.0(5)
118.9(6)
107.7(7)
60.89(5)
51.5(1)
130.83(5)
139.7(1)
79.4(1)
82.1(2)
144.1(2)
79.5(2)
S(3)-C(6)-O(1)
S(4)-C(6)-O(1)
C(6)-O(1)-C(7)
O(1)-C(7)-C(8)
S(1)-Te(1)--S(2)
S(3)-Te(1)--O(1)
S(3)-Te(1)--S(2)
S(1)-Te(1)--O(1)
S(2)--Te(1)--O(1)
C(1)-Te(1)--S(2)
C(2)-Te(1)--S(2)
C(1)-Te(1)--O(1)
C(2)-Te(1)--O(1)
C(1)-Te(1)--S(2)′
S(2)-Te(1)--S(2)′
Te(1)-S(2)--Te(1)′
S(1)-Te(1)--S(2)
S(3)-Te(1)--S(4)
S(3)-Te(1)--S(2)
S(1)-Te(1)--S(4)
S(2)--Te(1)--S(4)
C(1)-Te(1)--S(2)
C(2)-Te(1)--S(2)
C(1)-Te(1)--S(4)
C(2)-Te(1)--S(4)
C(1)-Te(1)--S(2)1
S(2)-Te(1)--S(2)1
Te(1)-S(2)--Te(1)1
59.7(1)
59.1(1)
136.7(1)
136.3(1)
77.7(1)
83.2(5)
141.0(5)
78.3(5)
140.7(4)
169.2(5)
107.37(9)
72.63(9)
135.6(2)
170.5(2)
107.28(4)
72.72(4)
aSymmetry equivalent position (1 – x, –y, –z) and (–x, –y, –z) by a double prime.
© 1999 NRC Canada

Drake et al.
1267
Fig. 1. ORTEP plots of the molecules (a) Me2Te[S2CNMe2][S2COEt],
8, and (b) Me2Te[S2CNEt2][S2COMe], 9. Atoms are drawn with
30% probability ellipsoids and spheres with hydrogen atoms
omitted for clarity.
Fig. 2. ORTEP plots of the molecules (a) Me2Te[S2CNMe2]
[S2COEt], 8, and (b) Me2Te[S2CNEt2][S2COMe], 9, showing the
stereochemistry about tellurium when the intramolecular
interactions leading to unsymmetrical ligands are included. The
atoms are drawn with 30% probability ellipsoids and spheres.
Hydrogen atoms are omitted for clarity.
S(4)
C(9)
O(1)
S(3)
C(6)
S(3)
C(8)
S(4)
C(9)
O(1)
C(8)
C(7)
S(4)
C(6)
C(7)
S(3)
O(1)
C(2)
S(3)
C(2)
Te(1)
Te(1)
C(8)
S(4)
O(1)
C(1)
C(1)
C(8)
Te(1)
Te(1)
S(2)
S(2)
C(1)
S(1)
S(1)
C(1)
C(2)
C(2)
S(2)
C(3)
S(2)
C(3)
(a)
(b)
S(1)
N(1)
S(1)
N(1)
C(6)
C(4)
C(4)
C(3)
C(3)
N(1)
C(5)
C(7)
N(1)
C(6)
C(7)
C(5)
C(4)
C(4)
C(5)
C(5)
(b)
(a)
amounts of Me2TeLL′ and Me2TeL′2. However, all three spe-
cies, simultaneously also undergo reductive elimination to
Me2Te and the diligands, so that the spectra become very
complicated. Qualitatively, the reductive elimination does
not appear to be a reversible process so eventually the solu-
tion becomes depleted of tellurium(IV) species. Qualitatively,
the disproportionation and reductive elimination appear to
be most evident for derivatives containing dithiocarbonate
ligands and least evident for those containing the cyclic
dithiophosphate ligands.
bis species Me2Te[S2NCMe2]2, Me2Te[S2COMe]2, and
Me2Te[S2COEt]2 have an average value of 2.63(1) Å, even
though in all three cases the two Te—S bonds have quite
different lengths ranging from 2.566(1) to 2.680(1) Å. In 8
and 9, the Te—S bonds to the S2CNR2 groups, 2.620(2) in 8
and 2.608(5) Å in 9, are shorter than those to the S2COR
groups, 2.650(2) in 8 and 2.620(5) Å in 9. In the absence of
any Te--S associations involving the bonded S atom at con-
tact distances less than the sum of the van der Waals radii of
3.86 Å (28), bonding to dithiocarbamates is apparently
slightly favored.
Crystal structures of Me2Te[S2CNMe2][S2COEt], 8, and
Me2Te[S2CNEt2][S2COMe], 9
Me2Te[S2CNMe2][S2COEt], 8, crystallizes in the space
group P1 and Me2Te[S2CNEt2][S2COMe], 9, in P21/c. The
ORTEP diagrams in Fig. 1a and 1b illustrate that in both
compounds the immediate environment about tellurium is
that of the sawhorse structure typical of tellurium(IV) com-
pounds in which the lone pair is assumed to be active
stereochemically and occupying an equatorial position in a
distorted trigonal bipyramid, approximately in the position
of the Te(1) label. The two methyl groups occupy the other
two equatorial positions; the C-Te-C bond angles of 95.3(3)°
and 96.4(7)° in 8 and 9, respectively, being close to the
value of 96(1)° in Me2Te[S2CN(CH2)3CH2][S2CN(CH2)4CH2]
(21), and similar to those of 93.9(2)°, 96.6(2)°, and 96.2(2)°
in related bis derivatives, Me2Te[S2CNMe2]2 (12),
Me2Te[S2COMe]2 (1),and Me2Te[S2COEt]2 (2), respectively.
The average Te—C bond length of 2.12(1) Å in 8 and 9 is
essentially the same as that in Me2Te[S2NCMe2]2 and the
two Me2Te[S2COR]2 species. The S-Te-S bond angle of
166.87(6)° for the axial sulfur atoms in 8 is close to that in
the mixed species, Me2Te[S2CN(CH2)3CH2][S2CN(CH2)4CH2]
(166.1(2)°), as well as in Me2Te[S2NCMe2]2 and
Me2Te[S2COR]2 (167.58(7)° and166.2(2)° avg., respec-
tively). By contrast, the value of 162.0(1)° in 9 is the same
as in Me2Te[S2CN(CH2)3CH2]2 (21), so it is difficult to de-
tect an obvious pattern or trend. The two Te—S bonds in the
The pendant sulfur atoms in the dithiocarbamate groups
are oriented toward the tellurium center to give Te—S
anisobonds of 3.205(1) in 8 and 3.277(4) Å in 9 (see Fig. 2a
and 2b). These values are typical for analogous dithiocar-
bamates and correspond to normalized Pauling partial bond
orders of about 0.25, which is compatible with their being
part of the coordination sphere. Similar Te—S anisobonds,
varying from 3.274(2) to 3.521(1) Å, occur in
Me2Te[S2COMe]2 and Me2Te[S2COEt]2 (2) as well as in the
two independent molecules of Me2TeCl[S2COEt] with val-
ues of 3.210(3) and 3.292(3) Å (29). Similarly, in
Me2Te[S2CNEt2][S2COMe], 9, there is an anisobond be-
tween Te(1)—S(4) of 3.346(5) Å involving the S2COMe
group (see Fig. 2b). Surprisingly, the orientation of the
S2COEt group in Me2Te[S2CNMe2][S2COEt], 8, is such that
the second sulfur atom is turned away from tellurium so that
Te(1)—S(4) is 5.085(2) Å and so clearly not bonded (see
Fig. 2a). The intramolecular association now involves the
oxygen of the OEt group with a Te(1)—O(1) distance of
3.145(5) Å. In a study of analogous monothiocarbonates
(30), the terminal oxygen atom is oriented toward the tellu-
rium center in Me2Te[SCO2(i-Pr)]2 and Me2TeCl[SCO2Me],
with Te—O (terminal) distances averaging 3.05(8) Å in the
former and 2.948(8)
Å in the latter. However, in
Ph2Te[SCO2(i-Pr)]2, one of the SCO2(i-Pr) groups has a Te—O
© 1999 NRC Canada

1268
Can. J. Chem. Vol. 77, 1999
Fig. 3. Plot of the molecule Me2Te[S2CNMe2][S2COEt], 8,
showing the intermolecular interactions involving the aniso-
bonded sulfur atoms leading to a dimer. Hydrogen atoms and the
carbon atoms of the phenyl rings other than those attached to
phosphorus are omitted for clarity.
Fig. 4. Plot of the molecule Me2Te[S2CNEt2][S2COMe], 9,
showing the intermolecular interactions involving the aniso-
bonded sulfur atoms leading to a dimer. Hydrogen atoms and the
carbon atoms of the phenyl rings other than those attached to
phosphorus are omitted for clarity.
S(4)'
O(1)
C(9)
C(4)
S(3)
S(3)'
C(5)
C(8)
C(2)
N(1)"
C(3)"
N(1)
C(3)
O(1)'
S(4)
C(1)
S(2)"
Te(1)
S(1)"
S(2)
Te(1)'
S(1)
S(1)
C(8)
S(1)'
Te(1)"
C(1)"
S(2)
Te(1)
S(2)'
C(7)
C(3)
C(1)
S(4)"
C(8)"
C(4)
C(5)
N(1)
C(2)"
C(2)
O(1)
C(6)
C(6)
S(3)"
O(1)"
C(7)
S(3)
S(4)
mon feature for dimethyltellurium derivatives with sulfur
ligands having been reported for Me2Te[S2COR]2 (1, 2),
Me2Te[SCO2R]2 (30), Me2Te[SCONR2]2 (31), and
Me2Te[S2CN(CH2)3CH2]2 (21), where the two dithio groups
have small dihedral angles. However, by contrast, in
Me2Te[S2CN(CH2)4CH2]2, the orientation of the two
dithiocarbamates results in a dihedral angle between the two
planar S2CN cores being 69.6(2)° so that the arrangement
about tellurium is better described as a distorted octahedral
with the lone pair apparently inactive (21). A similar ar-
rangement is found in Ph2Te[S2COEt]2 so again it is diffi-
cult to identify factors that determine these orientations.
An examination of possible intermolecular associations
reveals that both 8 and 9 have similar Te--S′ interactions in-
volving only the anisobonded sulfur atoms of the dithio-
carbamate groups as is illustrated by Figs. 3 and 4. The
Te(1)—S(2)′ distances are 3.567(2) and 3.585(5) Å for 8 and
9, respectively, which correspond to bond orders close to
0.15, leading to pseudo-dimers. Thus, despite the different
orientations of the dithiocarbonate groups in 8 and 9, neither
of which show any intermolecular distances indicative of as-
sociations, similar dimeric units are formed in 8 and 9 by
bridges in which the Te(1)-S(2)--Te′(1) and S(2)-Te(1)--
S′(2) angles are 72.72(4)° and 107.28(4)°, respectively, for 8
(see Fig. 3) and 72.63(9)° and 107.37(9)°, respectively, for 9
(see Fig. 4). A similar bridging system is found in
Me2TeI[S2CN(CH2)3CH2], where, in contrast with the
Me2TeX[S2CN(CH2)4CH2] analogues which all have the
halogen atoms acting as bridges, a rectangular bridge again
(terminal) distance of 3.050(5) Å, but the other is oriented
so that the Te—O(i-Pr) distance is 3.150(5) Å. This orienta-
tion is repeated in Me2TeBr[SCO2(i-Pr)] where the Te—O(i-
Pr) distance is 2.930(6) Å. Thus, again it is difficult to detect
a consistent trend.
In Me2Te[S2CNEt2][S2COMe], 9, the orientations of the
dithiocarbamate and dithiocarbonate groups result in the five
atoms, S(1), S(2), S(3), S(4), and C(2), as well as
Te(1) forming an approximate plane (mean deviation from
plane of 0.1164 Å) with C(1) above the plane (2.06(1) Å) to
give an approximate pentagonal pyramidal arrangement
about Te(1) or a pentagonal bipyramidal arrangement if the
lone pair is assumed to be occupying the axial position trans
to C(1) (see Fig. 2b). The two planar S2CN and S2CO cores
of the dithio groups have a dihedral angle of 10.4(1)°. By
contrast, in Me2Te[S2CN(CH2)3CH2][S2CN(CH2)4CH2], the
dihedral angle between the two different dithiocarbamate
groups is only 1.4(1)°. Despite the fact that the oxygen atom
of the OEt group is turned toward tellurium in
Me2Te[S2CNMe2][S2COEt], 8, rather than the terminal sul-
fur atom as can be seen from Fig. 2a, there is still an ap-
proximate plane (mean deviation from plane of 0.0946 Å)
around tellurium with the five atoms, S(1), S(2), S(3), C(2),
and now O(1) as well as Te(1) forming the plane with
C(1) above the plane (2.08(1) Å). The two planar S2CN and
S2CO cores of the dithio groups have a dihedral angle of
only 3.9(1)°. Similar pentagonal planes appear to be a com-
© 1999 NRC Canada

Drake et al.
1269
leads to pseudo-dimers with Te(1)-S(2)--Te′(1) and S(2)-
Te(1)--S′(2) angles of 76.19(9)° and 103.8(1)°, respectively
(21). Surprisingly, there are no comparable Te--S--Te
bridges in the bis-Me2Te[S2CN(CH2)nCH2]2 species. In gen-
eral, dithiocarbonates apparently do not tend to form inter-
molecular interactions through the sulfur atoms.
sponds to the ν(C-S) stretch of the terminal or aniso sulfur
atom (7, 8, 12). In tellurium dithiocarbonates, three strong
features define the presence of stretching modes involving
the stretching of the CO and CS bonds within the moiety
S2COC. As was confirmed by normal coordinates analyses,
there is considerable mixing amongst these modes that are
seen at ca. 1200, 1120, and 1040 cm–1, and hence, they are
assigned as ν(S2COC)a, ν(S2COC)b, and ν(S2COC)c, respec-
tively (29). Strong bands in the infrared spectra in the region
995–900 cm–1 provide characteristic features indicative of the
presence of the alkylene dithiophophate group in
Me2Te[S2POCMe2CMe2O]2 and Me2Te[S2POCH2CMe2CH2O]2,
which are attributable to ring vibrations that are probably
coupled with C-C stretching vibrations (20, 30, 31). In com-
pounds 1–9, the above features are seen for the appropriate
groups at similar, but not identical positions, to the corre-
As with other dithiocarbamates, the (Te)S-C-N angles are
all less than 120°, at 117.0(5)° and 114(1)° for 8 and 9, re-
spectively, whereas the (Te)S-C-S and S-C-N angles are all
over 120°, averaging 122(1)°, which is consistent with the π-
bond delocalization within the S2CN planar moiety being of
greater importance in the S2C—N and TeS(N)C—S bonds.
The (Te)S—C bonds (1.756(9) Å avg.) are typical of an
S—C bond attached to the stronger Te—S bond in aniso-
bidentate di- and monothiocarbamate derivatives (31) and
also shorter than the sum of the covalent radii of C and S of
1.81 Å, suggesting a small degree of participation in the
delocalized π-bonding. The C—S bond involving the aniso-
bonded sulfur atom is shorter, with an average length of
1.676(9) Å. This is still considerably longer than a C=S
bond (ca. 1.56 Å in CS2, COS, or CSTe (32)) but similar to
that observed in species such as (NH2)2CS and thus consis-
tent with a considerable degree of partial π-bond character as
well as an anisobidentate link. Not only are the dithiocar-
bonate groups planar in terms of the sulfur and oxygen at-
oms about the central carbon, with a mean deviation of
0.003 Å in 8 and 0.004 Å in 9, but so to a first approxima-
tion are the ethyl and methyl groups; C(7) and C(8) being
out of plane by only 0.050 and 0.068 Å, respectively, in 8
and C(9) only 0.018 Å out of the plane in 9. The terminal
C=S bond in 8 (1.633(7) Å) is apparently shorter than the
anisobonded C=S(--Te) bond in 9 (1.66(2) Å), and con-
versely, the C—STe bond in 8 (1.74(2) Å) is longer than in 9
(1.729(7) Å). The bond lengths and angles within the S2CO
moiety are in the same range as those reported for
bis compounds. Thus, for example, for
sponding
Me2Te[S2CNMe2][S2POCH2CMe2CH2O] (3), ν(C-NR2) and
ν(C-S) are seen at 1517 and 968 cm–1, respectively, in the
infrared and Raman spectra, compared to 1491 and 973 cm–1
in Me2Te[S2CNMe2]2 (12), and the most distinct ring
vibration in Me2Te[S2POCH2CMe2CH2O]2 at 994 cm–1 is
seen at 985 cm–1 in 3. All of this data is indicative of the
presence of a mixed species rather than a mixture of two bis
compounds.
The characteristic peaks corresponding to the Te-C asym-
metric and symmetric stretches are prominent in all of the
Raman spectra of 1–9, in general having values for ν(Te-
C)asym (531–541 cm–1) that are closer to those found in
Me2Te[S2COR]2 or Me2TeCl[S2COR] (533–544 cm–1) than
to Me2Te[S2POCMe2CMe2O]2 and Me2Te[S2POCH2CMe2CH2O]2
(ca. 529 cm–1) (20). In Me2Te[S2CNMe2][S2COEt], 8, whose
structure has been described above, the two Te-S stretches
are assigned to 359 and 317 cm–1, compared to the asym-
metric and symmetric stretches in Me2Te[S2CNMe2]2 (362
and 349 cm–1) and Me2Te[S2COEt]2 (382 and 301 cm–1),
which is of course consistent with the mixed compound
rather than a mixture, as can be illustrated for all nine com-
pounds. While the mixing between the two Te-S modes is
going to still be significant in 1–9, the groups are not equiv-
alent as in bis compounds. The Te—S bond to the dithio-
carbamate is slightly shorter, so the band at 359 cm–1
probably has a greater contribution from Te-S(CNR2) and
that at 317 cm–1 a corresponding contribution from Te-S(COR).
Both bands are seen at slightly higher wave number in
Me2Te[S2CNEt2][S2COMe], 9, at 369 and 328 cm–1, which
is at least consistent with both bonds being slightly shorter
in 9 than in 8. For the compounds containing a dithiophos-
phate group, 1–6, it is reasonable to assign the band at
higher wave number as having more contribution from Te-
Me2Te[S2COEt]2
(2),
Me2Te[S2COMe]2
(1),
and
Me2TeCl[S2COEt]2 (29), which emphasizes the rigidity of
the ligand regardless of its orientation about tellurium or
whether it is in a mixed ligand species, bis compound, or
haloderivative.
The S(1)-Te(1)-S(2) bite angles of the two dithiocar-
bamate groups are 60.89(2)° and 59.7(1)° with “bites” of
2.994(3) and 2.987(6) Å in 8 and 9, respectively, which are
typical of anisobidentate dithiocarbamates. Similarly, the
S(3)--S(4) bite angle in 9 of 59.1(1)° in the dithiocarbonate
is close to the average of the two angles in Me2Te[S2COEt]2
(2). In view of the rigidity of the planar groups, not surpris-
ingly, the S(3)—S(4) distances in 8 and 9 are similar.
Infrared and Raman spectra
Selected features in the infrared and Raman spectra and
their assignments are given in Table 3. In considering these
mixed species, it is useful to establish those features among
the plethora of peaks, especially those associated with the
presence of the CH3 and CH2 groups, that most clearly iden-
tify the presence of the particular dithiocarbamate, dithiocar-
bonate, or alkylene dithiophosphate group. In tellurium
dithiocarbamate species, a distinctive peak in the infrared
spectrum between 1484 and 1508 cm–1 corresponds to the
ν(C-NR2) stretching vibration, and one generally of medium
intensity in both effects between 963 and 985 cm–1 corre-
S(CNR ) or Te-S(COR), because in the bis compounds
,
2
Me2Te[S2POCMe2CMe2O]2 and Me2Te[S2POCH2CMe2CH2O]2,
the Te-S stretches were assigned at lower wave number than
in the bis dithiocarbamates and -carbonates (20).
NMR spectra
The 13C{1H} NMR spectral data for compounds 1–9 are
presented in Table 4. Although the peaks corresponding to
the S2CN and S2CO carbon atom are the weakest in every
spectrum, they provide definitive evidence for the formation
© 1999 NRC Canada

1270
Can. J. Chem. Vol. 77, 1999
Table 3. Selected features (cm–1) and their assignments in the vibrational spectra of Me2Te[S2CNMe2][S2POCMe2CMe2O], 1,
Me2Te[S2CNEt2][S2POCMe2CMe2O], 2, Me2Te[S2CNMe2][S2POCH2CMe2CH2O], 3, Me2Te[S2CNEt2][S2POCH2CMe2CH2O], 4,
Me2Te[S2COMe][S2POCMe2CMe2O], 5, Me2Te[S2COEt][S2POCMe2CMe2O], 6, Me2Te[S2CNMe2][S2COMe], 7,
Me2Te[S2CNMe2][S2COEt], 8, Me2Te[S2CNEt2][S2COMe], 9.a,b,c
1
2
3
4
5
6
7
8
9
Assignment
ν (C-NR2)
1504 ms
1490 s
1517 s
1483 s
1496 ms
1501 s
1483 vs
1205 vs
1145 vs
1048 vs
1013 sh
1200 vs
1140 vs
1042 vs
1010 sh
1195 ms
1130 s
1187 s
1110 s
1031 vs
1201 vs
1139 vs
1050 vs
ν (S2COC)a
ν (S2COC)b
ν (S2COC)c
ν (PO-C)
Ring
1045 vs
1009 mw
1007 m
1046 vs
1045 s
992 vs, br
985 vs, br
995 [5]
980 [5]
968 s
968 [10]
961 s
966 [35]
989 m
985 [15]
965 sh
968 [30]
983 [20]
971 s
969 [20]
984 ms
982 [15]
ν (S=CSNR2)
Ring
911 vs
917 s
910 m
909 ms
908 vs
910 vs
915 [5]
911 [10]
914 [15]
818 mw
815 ms
806 m
805 s
821 mw
815 mw
ν (PO2)sym
820 [10]
820 [5]
814 [5]
810 [10]
820 [15]
820 [15]
537 [40]
515 [90]
537 [40]
512 [80]
377 s
539 [40]
517 [90]
373 ms
537 [60]
532 [30]
533 [30]
525 [50]
531 [20]
515 [40]
541 [30]
527 [40]
534 [100] ν (Te-C)asym
523 [100] 525 [50]
520 [60]
ν (Te-C)sym
ν (Te-S)asym
373 m
374 ms
352 m
361 mw
370 ms
356 ms
358 ms
372 [100]
378 [100] 372 [100]
373 [90]
361 [30]
361 [20]
368 [100]
359 [70]
369 [80]
296 mw
330 ms
298 mw
333 ms
309 mw
310 ms
351 s
316 ms
326 m
ν (Te-S)sym
293 [30]
333 [25]
303 [5]
335 [20]
313 [100] 313 [100]
350 [10]
317 [100] 328 [10]
aIR assignments in italic with s = strong, m = medium, w = weak, sh = shoulder, br = broad, and v = very.
bSquare brackets denote relative intensities in the Raman effect.
cIR spectra run between KBr plates down to 400 cm–1 and between polyethylene below 400 cm–1.
dRaman spectra run neat in sealed tubes.
Table 4. 13C, 31P, and 125Te NMR chemical shifts for the mixed ligand dimethyltellurium derivatives 1–9.a,b,c
Compounds 1–9
TeCH3 POC
POCC
NC
NCC OC
OCC NCS2 OCS2 31P
125Te
Me2Te[S2CNMe2][S2POCMe2CMe2O], 1d
17.32
89.25
24.40 d 44.35
[17.6]
196.0 109.5 525
Me2Te[S2CNEt2][S2POCMe2CMe2O], 2
17.29
89.09
24.4
32.67
49.01 12.14
44.59
194.8 110.0 525
Me2Te[S2CNMe2][S2POCH2CMe2CH2O], 3d 17.40
75.98 d
[29.4]
75.81 d
[29.4]
89.70
196
97.6 522
Me2Te[S2CNEt2][S2POCH2CMe2CH2O], 4d
Me2Te[S2COMe][S2POCMe2CMe2O], 5
17.55
16.89
32.70 d 49.22 12.69
[18.0]
24.32 d
194.2
98.1 519
61.22
222.9 107.5 539
[19.4]
24.30
44.34
44.25
Me2Te[S2COEt][S2POCMe2CMe2O], 6
Me2Te[S2CNMe2][S2COMe], 7
Me2Te[S2CNMe2][S2COEt], 8
Me2Te[S2CNEt2][S2COMe], 9
16.85
16.19
16.17
16.34
89.89
71.24 13.95
60.62
70.42 14.16 199.1 221.2
222.3 107.7 536
198.9 222.2
491
488
474
48.88 12.59 60.29
197.2 222.0
aThe spectra were recorded in CDCl3 and reported in ppm from Me4Si for 13C, from H3PO4 for 31P, and from Me2Te for 125Te.
bAll peaks are singlets, the doublets arising from J(PC) coupling are marked with a d.
cCoupling constants in Hz shown in square brackets.
dPOCCC for 3 and 4, 21.93 and 21.95 ppm, respectively.
© 1999 NRC Canada

1
Table 5. H NMR chemical shifts for the mixed ligand dimethyltellurium derivatives 1–9.a,b,c
Compounds 1–9
Te-CH3
POCnCH3
1.43
PO-CH2
N-CH3/CH2
NCH2-CH3
O-CH3/CH2
OC-CH3
Me2Te[S2CNMe2][S2POCMe2CMe2O], 1
2.54
3.43 (6 H, s)
(6 H, s)
(12 H, s)
1.43
Me2Te[S2CNEt2][S2POCMe2CMe2O], 2
Me2Te[S2CNMe2][S2POCH2CMe2CH2O], 3d
Me2Te[S2CNEt2][S2POCH2CMe2CH2O], 4d
Me2Te[S2COMe][S2POCMe2CMe2O], 5
Me2Te[S2COEt][S2POCMe2CMe2O], 6
2.54
3.83 (4 H, q)
1.25 (6 H, t)
(6 H, s)
2.59
(6 H, s)
2.59
(6 H, s)
(12 H, s)
1.04
[J(HH) 7.0]
3.43 (6 H, s)
[J(HH) 7.0]
4.02 (4 H, d)
(6 H, s)
1.03
[J(PH) 15.5]
4.02 (4 H,d)
3.82 (4 H, q)
1.26 (6 H, t)
(6 H, s)
1.43
[J(PH) 15.5]
[J(HH) 7.1]
[J(HH) 7.1]
2.61
(6 H, s)
4.12 (3 H, s)
4.55 (2 H, q)
(12 H, s)
1.41
2.58
1.39
(12 H, s)
[J(HH) 7.1]
(3 H, t)e
(6 H, s)
Me2Te[S2CNMe2][S2COMe], 7
Me2Te[S2CNMe2][S2COEt], 8
Me2Te[S2CNEt2][S2COMe], 9
2.47
(6 H, s)
2.49
(6 H, s)
2.45
3.42 (6 H, s)
3.44 (6 H, s)
4.07 (3 H, s)
4.55 (2 H, q)
[J(HH) 7.1]
4.05 (3 H, s)
1.39 (3 H, t)
[J(HH) 7.1]
3.85 (4 H, q)
1.26 (6 H, t)
(6 H, s)
[J(HH) 7.1]
[J(HH) 7.1]
aThe spectra were recorded in CDCl3 and reported in ppm from Me4Si.
bNumber of protons and multiplicities are in parentheses (s = singlet; t = triplet; d = doublet; q = quartet).
cCoupling constants in Hz shown in square brackets.
dPO-CH2 for 3 and 4 are both 4.02 (4 H, d) (J(PH) = 15.5) ppm.
ePartially masked by the large singlet at 1.41 ppm.

1272
Can. J. Chem. Vol. 77, 1999
of the mixed ligand Me2TeLL′ species. Thus, for example, in
the spectrum of Me2Te[S2CNMe2][S2COMe], 9, for which
we have the solid state structure, two peaks are seen at 198.9
and 222.2 ppm which correspond to the S2CN and S2CO
peaks, respectively. These are shifted slightly but defini-
tively from those of the corresponding bis species,
Me2Te[S2CNMe2]2 at 200.0 and Me2Te[S2COMe]2 at
220.9 ppm (12, 2). When the spectra are rerecorded after
24 h, two additional peaks corresponding to the two bis spe-
cies are present. Identical features are seen in the spectra of
compounds 7 and 8. In compounds 1–4, which contain a
cyclic dithiophosphate instead of a dithiocarbonate, the shift
of the S2CN carbon is more marked.
tensity. The peak due to Me2Te[S2COR]2 dies away more
rapidly, presumably reflecting the fact that the
dithiocarbonate derivatives more readily undergo reductive
elimination to Me2Te and diligand.
1
The H NMR spectral data for compounds 1–9 are sum-
marized in Table 5. The splitting patterns and intensities of
1
peaks in the H NMR spectra of all of these compounds are
found to be consistent with the structures of 7 and 8, and by
extension to all of the other derivatives. All compounds, 1–
9, show a sharp singlet assignable to the CH3 groups at-
tached to tellurium in the range 2.45–2.54 ppm. The CH3Te
chemical shifts are close to but not quite additive for com-
pounds 1–6 and essentially additive for 7–9 in that they all
lie close to the average value of the two analogous bis deriv-
atives. As was the case for the 13C NMR spectra, the chemi-
cal shifts of protons within the ligands are close to but not
identical to those of the bis ligand species. In all derivatives
containing a dithiocarbamate group, compounds 1–4 and 7–
9, the two CH3 or CH3CH2 groups show no signs of
nonequivalence despite the fact that the nitrogen atom is
clearly planar in the solid state structures of 8 and 9. There
is still no sign of coalescence in low-temperature runs. Simi-
larly, in the compounds containing the dithiophosphate
groups, 1–6, only single peaks are seen for the CH3 protons
of the dithiophosphate groups even though they have the po-
tential to be in nonequivalent positions. This is the same as
was observed for the corresponding bis species, where non-
equivalent positions were seen in solid state structures (20).
Compounds 3 and 4 have hydrogen atoms attached to the α-
carbon atom of the glycoxy groups, which display geminal
The peak attributed to the TeCH3 carbon is at 17.32 ppm
in Me2Te[S2CNMe2][S2POCMe2CMe2O], 1, which is
slightly less than the average value of the chemical shift for
their bis analogues Me2Te[S2POCMe2CMe2O]2 and
Me2Te[S2CNMe2]2, which are at 19.2 and 16.6 ppm, respec-
tively (12, 20). The chemical shifts in 2–4 range from 17.29
to 17.55 ppm but in compounds 5 and 6 are at ca. 16.9 ppm,
which is closer to the value of ca. 15.6 ppm found in the bis
dithiocarbonates (2). In the mixed ligand compounds that
contain dithiocarbamate and -carbonate, 7–9, the TeCH3
shifts are essentially the average of the bis species, so the
contributions appear to be additive. All of the carbon atoms
in the ligands have very similar, though not identical, chemi-
cal shifts to those observed in the analogous bis compounds
(2, 12, 20). The doublets arising from P-C coupling and the
values of the JPC coupling constants are as observed for the
bis compounds and (or) related cyclic dithiophosphate deriv-
atives (20, 33).
J
coupling with phosphorus with (PH) values of 15.5 Hz that
The 31P{H} NMR spectra of fresh samples show single
peaks (see Table 4) in the region 107.5–110.0 ppm for com-
are the same as in the bis species and appear to be more typ-
ical of bidentate than monodentate linkages.
1, 2, 5, and 6, relative to a peak at 105.0 ppm i
pounds
Me2Te[S2POCMe2CMe2O]2, and at 97.6 and 98.1 ppm for
compounds 3 and 4, respectively, relative to 92.0 ppm i
n
Concluding comments
n
The study demonstrates that, despite the well-known pro-
pensity of Me2TeL2 species, where L is a dithio ligand, to
undergo exchange and reductive elimination, mixed ligand
species of the type Me2TeLL′, are formed in both stepwise
and in situ reactions and are not just fortuitous 1:1 mixtures
of Me2TeL2 and Me2TeL′2 derivatives. Surprisingly, the ori-
entations of the dithiocarbonate groups differ in
Me2Te[S2CNMe2][S2COEt], 8, and Me2Te[S2CNEt2][S2COMe],
9; having the pendant sulfur atom turned toward tellurium in
9 as has been found for the corresponding bis dithiocar-
bonate species, Me2Te[S2COEt]2 and Me2Te[S2COMe]2, but
away from tellurium in 8. This suggests that the difference
in energy when aniso bonds are formed between OR groups
or terminal S atoms, must be very small and easily overrid-
den by other effects. Despite the difference in the
intramolecular associations in 8 and 9, the intermolecular as-
sociation to make pseudo dimers is identical in both result-
ing in Te–S–Te–S rectangular bridges involving the pendant
sulfur atom of the dithiocarbamate groups.
Me2Te[S2POCH2CMe2CH2O]2 (20). These constitute down-
field shifts relative to the free cyclic dithiophosphoric acids
of the order of 15.1–17.6 ppm when a dithiocarbamate is
present with the dithiophosphate and of the order of 20.5–
21.0 ppm when a dithiocarbonate is present. These shifts ap-
pear to favor the concept that the dithiophosphates are es-
sentially bidentate in solution (34), presumably through
rapid exchange. When the spectra were recorded again after
the solutions had been left standing, peaks at 105 or 92 ppm
were observed arising from the formation of
Me2Te[S2POCMe2CMe2O]2 or Me2Te[S2POCH2CMe2CH2O]2,
respectively, as the result of disproportionation and grew
over several days to be approximately equal in height with
that of the Me2TeLL′ species.
The 125Te NMR spectra of freshly prepared solutions (Ta-
ble 4) show a single peak whose chemical shift is reasonably
close to the average value for the related bis compounds and
hence in the range 519–528 ppm for compounds 1–4, 539
and 536 ppm for 5 and 6, and 474–491 ppm for 7–9. The
spectra of compounds 7–9 show evidence of the presence of
the bis species, indicating that disproportionation is already
significant in the time taken to run a 125Te NMR spectrum in
species that do not contain a cyclic dithiophosphate. Over a
period of approximately three days, the relative peak heights
of the bis species increase, although all are decreasing in in-
Acknowledgement
We wish to thank the Natural Sciences and Engineering
Research Council of Canada and Imperial Oil Canada for fi-
nancial support. One of us (R.R.) thanks Dayanand College,
© 1999 NRC Canada

Drake et al.
1273
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Ajmer, India for granting a leave of absence, and one of us
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© 1999 NRC Canada