Formation and characterization of platinum and palladium complexes of bis(trimethylsilylmethyl)tellane

Article abstract of DOI:10.1002/ejic.200700838

The mononuclear (telluroether)platinum and -palladium complexes cis-[PtCl₂{Te(CH₂SiMe₃)₂} ₂] (2c), trans-[PtCl₂{Te(CH₂SiMe ₃)₂}₂] (2t), and trans-[PdCl ₂{Te(CH₂SiMe₃)₂}₂] (3t) have been prepared from bis(trimethylsilylmethyl)tellane and bis(benzonitrile)dichloridoplatinum and -palladium and structurally characterized by single-crystal X-ray diffraction and NMR spectroscopy. The isomer distribution of the platinum complex depends on the initial molar ratio of the reactants. When [PtCl₂(NCPh)₂] was used in excess, 2c was the main product. Upon increasing the initial ligand/metal molar ratio, the relative amount of 2t increased. The stoichiometric reaction afforded approximately equal amounts of the cis and trans isomers. Further increase of the initial amount of the ligand yielded 2t. The mononuclear palladium complex was the trans isomer 3t, regardless of the initial molar ratio of the reactants. Small amounts of the dinuclear complex [Pt₂Cl₄{μ- Te(CH₂SiMe₃)₂}{Te(CH₂SiMe ₃)₂}₂] (4) were also formed, when the initial ligand/metal molar ratio was low. Compound 4 shows a rare bridging telluroether ligand and two different platinum coordination environments, one exhibiting a cis-Cl/cis-TeR₂ arrangement and the other a trans-Cl/trans-TeR ₂ arrangement. In case of palladium, the equimolar reaction afforded [Pd₂(μ-Cl)₂Cl₂{Te(CH₂SiMe ₃)₂}₂] (5) in good yields. As the relative amount of the ligand was increased, also 3t was formed. When the ligand/metal ratio was >2:1, 3t was the only product. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200700838

FULL PAPER
DOI: 10.1002/ejic.200700838
Formation and Characterization of Platinum and Palladium Complexes of
Bis(trimethylsilylmethyl)tellane
Ludmila Vigo,[a] Raija Oilunkaniemi,*[a] and Risto S. Laitinen*[a]
Keywords: Bis(trimethylsilylmethyl)tellane / Platinum complexes / Palladium complexes / X-ray diffraction / NMR spec-
troscopy
The mononuclear (telluroether)platinum and -palladium
complexes cis-[PtCl2{Te(CH2SiMe3)2}2] (2c), trans-[PtCl2{Te-
(CH2SiMe3)2}2] (2t), and trans-[PdCl2{Te(CH2SiMe3)2}2] (3t)
have been prepared from bis(trimethylsilylmethyl)tellane
and bis(benzonitrile)dichloridoplatinum and -palladium and
structurally characterized by single-crystal X-ray diffraction
and NMR spectroscopy. The isomer distribution of the plati-
num complex depends on the initial molar ratio of the reac-
tants. When [PtCl2(NCPh)2] was used in excess, 2c was the
main product. Upon increasing the initial ligand/metal molar
ratio, the relative amount of 2t increased. The stoichiometric
reaction afforded approximately equal amounts of the cis and
trans isomers. Further increase of the initial amount of the
ligand yielded 2t. The mononuclear palladium complex was
the trans isomer 3t, regardless of the initial molar ratio of the
reactants. Small amounts of the dinuclear complex [Pt2Cl4{µ-
Te(CH2SiMe3)2}{Te(CH2SiMe3)2}2] (4) were also formed,
when the initial ligand/metal molar ratio was low. Compound
4 shows a rare bridging telluroether ligand and two different
platinum coordination environments, one exhibiting a cis-Cl/
cis-TeR2 arrangement and the other a trans-Cl/trans-TeR2 ar-
rangement. In case of palladium, the equimolar reaction af-
forded [Pd2(µ-Cl)2Cl2{Te(CH2SiMe3)2}2] (5) in good yields. As
the relative amount of the ligand was increased, also 3t was
formed. When the ligand/metal ratio was Ͼ2:1, 3t was the
only product.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
Our recent DFT calculations using [MCl2(EMe2)2] (M =
Pt, Pd; E = S, Se, Te) as model complexes have consistently
indicated that, while the trans isomers of the Pd complexes
lie at significantly lower energy than the cis isomers, in the
case of Pt complexes the energy difference is smaller and
decreases, as the chalcogen atom of the chalcogenoether li-
gand becomes heavier.[9]
Introduction
In the absence of steric and chelating effects, many
[MX2(ERRЈ)2] (M = Pd, Pt; X = Cl, Br, I; E = S, Se, Te;
R, RЈ = alkyl, aryl) complexes show the presence of both
trans and cis isomers in solution with the trans/cis ratio in-
creasing in the order Pt Ͻ Pd and Cl Ͻ Br Ͻ I (for some
selected reviews, see refs.[1–7]). Facile pyramidal inversion
has been deduced to take place about the chalcogen center
and has also been extensively investigated.[8] In the solid
state, the monodentate [PtX2(SRRЈ)2] complexes show ap-
proximately an even distribution of the occurrence of trans
and cis isomers.[9] While information on the corresponding
seleno- and telluroether complexes is much sparser, the exis-
tence of both trans and cis isomers has also been estab-
lished.[10–16] By contrast, most [PdX2(SRRЈ)2] complexes[9]
as well as their seleno- and telluroether analogues[17–25] exist
as trans isomers both in solution and in the solid state, the
sole exceptions being [PdCl2(TeMeR)2] [R = 2-thienyl
(C4H3S) or 2-furyl (C4H3O)].[13] Even these latter two com-
plexes show the presence of both isomers in solution.
Gysling et al.[26] have reported the preparation of related
[PdCl2{Te[(CH2)nSiMe3]2}2] (n = 1,3) complexes involving
bis(trimethylsilylalkyl)tellane ligands. Both complexes were
inferred to be trans isomers on the basis of far-IR and Ra-
man spectra. In solution of the corresponding thiocyanate
complex [Pd(SCN)2{Te[(CH2)3SiMe3]2}2], a small amount
of the cis isomer was also inferred to be present. The crystal
structure revealed the trans isomer of the complex.[26]
In this work we explore further the factors affecting the
formation and isomerism of mono- and dinuclear bis(trime-
thylsilylmethyl)tellane (Me3SiCH2)2Te (1) complexes of
platinum and palladium. The formation and structural
characterization of mononuclear cis-[PtCl2{Te(CH2Si-
Me3)2}2] (2c), trans-[PtCl2{Te(CH2SiMe3)2}2] (2t), and
trans-[PdCl2{Te(CH2SiMe3)2}2] (3t) are described. The re-
action involving platinum also affords a small amount of
dinuclear [Pt2Cl4{µ-Te(CH2SiMe3)2}{Te(CH2SiMe3)2}2] (4)
that shows unprecedented structural features. By contrast,
a dinuclear palladium complex [Pd2(µ-Cl)2Cl2{Te(CH2Si-
Me3)2}2] (5) is produced in good yields.
[a] Department of Chemistry,University of Oulu,
P. O. Box 3000, 90014 Oulu, Finland
Fax: +358-8-5531608
E-mail: risto.laitinen@oulu.fi
raija.oilunkaniemi@oulu.fi
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
284
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Platinum and Palladium Complexes of Bis(trimethylsilylmethyl)tellane
Results and Discussion
the relative amount of 1 was increased, the formation of the
mononuclear complex 3t was also observed in the reaction
mixture. The stoichiometric reaction and that with an ex-
cess of 1 afforded only trans-[PdCl2{Te(CH2SiMe3)2}2] (3t).
Complex Formation
The reaction of 1 with [PtCl2(NCPh)2] (molar ratio 2:1)
produces mononuclear [PtCl2{Te(CH2SiMe3)2}2] in good
yield. The 195Pt and 125Te NMR spectra were recorded for
the reaction mixture. Two resonances are observed in the
125Te NMR spectrum at δ = 266 (1JPt–Te = 804 Hz) and 292
(1JPt–Te = 469 Hz) ppm and assigned to cis and trans iso-
mers (2c and 2t), respectively. The assignment of the 125Te
Crystal Structures
The lattices of 2c, 2t, 3t, 4, and 5 each consists of discrete
complexes and show slightly distorted square-planar coor-
dination environments around the platinum and palladium
centers [ΣαM(M = Pt or Pd) span a very narrow range of
360.00–360.02°]. In addition, the lattice of complex 4 con-
tains ½ mol of benzene for each mol of 4. This molecule is
a carry-over from the initial synthesis that was performed
in benzene.
1
chemical shifts is based on the JPt–Te coupling information
reported previously for cis- and trans-[PtCl2(TeMe2)2]
(824 Hz and 489 Hz, respectively).[27] The larger coupling
constant of the cis isomer than that of the trans isomer is
consistent with the stronger trans influence of tellurium
compared to that of chlorine.[4,27] The 195Pt NMR spectrum
also exhibits two resonances observed at δ = –4236 and
–3707 ppm. They are assigned to 2c and 2t, respectively,
based on their relative intensities compared to those of the
125Te resonances. Both 195Pt resonances exhibit 125Te satel-
lites that yield JPt–Te coupling constants, which are consis-
tent with this assignment.
It is interesting to note that the isomeric composition of
the reaction solution containing [PtCl2{Te(CH2SiMe3)2}2]
is dependent on the initial molar ratios of 1 and
[PtCl2(NCPh)2] (see Figure S1 in the Supporting Infor-
mation). Upon using an excess of [PtCl2(NCPh)2], cis-
[PtCl2{Te(CH2SiMe3)2}2] (2c) is the predominant isomer.
As the ligand/metal molar ratio increases, the relative con-
centration of the trans isomer increases and that of the cis
isomer decreases. The nominally stoichiometric reaction
(reactant ligand/metal molar ratio is 2:1) affords approxi-
mately equimolar amounts of cis and trans isomers, as has
previously been observed for many chalcogenoether com-
plexes.[4] As the initial amount of the ligand 1 is further
Mononuclear Complexes
The molecular structures of the mononuclear complexes
2c, 2t, and 3t are shown in Figures 1 and 2 and their se-
lected bond parameters in Table 1. The Pt–Te bond lengths
in 2c and 2t are 2.537(1)–2.525(1) Å and 2.5807(6) Å,
respectively. The longer bond length in the trans complex
is consistent with the stronger trans influence of tellurium
compared to that of chlorine. It also supports the assign-
ments of the 125Te and 195Pt resonances. The same trend
can also be deduced by comparing the Pt–Te distances in,
for instance, cis-[PtCl2{Te(nBu)CH2}2SiMe2] [2.497(1) and
2.506(2) Å][28]
and
trans-[PtCl2{Te(CH2)2O(CH2)2}2]
[2.5945(3) Å].[15] The relative magnitudes of the trans influ-
ence of tellurium and chlorine can also be inferred by the
Pt–Cl distances of 2.321(3)–2.351(3) Å and 2.309(2) Å in 2c
and 2t, respectively. They can again be compared to the
corresponding distances in cis-[PtCl2{Te(nBu)CH2}2SiMe2]
[2.335(6)–2.353(5) Å][28] and in trans-[PtCl2{Te(CH2)2O-
(CH2)2}2] [2.317(3) Å].[15]
increased,
the
relative
concentration
of
trans-
[PtCl2{Te(CH2SiMe3)2}2] (2t) quickly increases and the spe-
cies becomes the main isomer in solution.
By contrast, trans-[PdCl2{Te(CH2SiMe3)2}2] (3t) is the
sole mononuclear product in the reaction of 1 with
[PdCl2(NCPh)2], regardless of the initial ligand/metal molar
ratio. The 125Te chemical shift of the complex is observed
at δ = 306 ppm.
At low initial ligand/metal ratio, the reaction of 1 and
[PtCl2(NCPh)2] afforded small amounts of dinuclear
[Pt2Cl4{Te(CH2SiMe3)2}3] (4) in addition to the mononu-
clear complexes 2c and 2t. A crop of crystals, the habits of
which were sufficiently different to allow for their manual
separation from the main mononuclear products, was ob-
tained upon crystallization of the reaction solution. The
yield of 4 was too small to facilitate bulk characterization.
X-ray quality crystals, however, could be obtained upon
recrystallization from dichloromethane.
The equimolar reaction of 1 and [PdCl2(NCPh)2] af-
forded the dinuclear palladium complex [Pd2(µ-Cl)2Cl2-
{Te(CH2SiMe3)2}2] (5) in good yields. Only one resonance
Figure 1. Molecular structure of cis-[PtCl2{Te(CH2SiMe3)2}2] (2c)
indicating the numbering of atoms. The thermal ellipsoids have
is observed in the 125Te NMR spectrum at δ = 501 ppm. As been drawn at 50% probability level.
Eur. J. Inorg. Chem. 2008, 284–290
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L. Vigo, R. Oilunkaniemi, R. S. Laitinen
FULL PAPER
Table 1. Selected bond lengths [Å] and angles [°] of cis-
[PtCl2{Te(CH2SiMe3)2}2] (2c), trans-[PtCl2{Te(CH2SiMe3)2}2] (2t),
and trans-[PdCl2{Te(CH2SiMe3)2}2] (3t).
Parameter
2c
2t (M = Pt) 3t (M = Pd)
M(1)–Te(1)
M(1)–Te(2)
M(1)–Cl(1)
M(1)–Cl(2)
2.537(1)
2.525(1)
2.351(3)
2.321(3)
2.5807(6)
2.309(2)
180.0
2.5910(5)
2.302(1)
180.0
Te(1)–M(1)–Te(1)[a]
Te(1)–M(1)–Te(2)
Te(1)–M(1)–Cl(1)
Te(1)–M(1)–Cl(1)[a]
Te(1)–M(1)–Cl(2)
Te(2)–M(1)–Cl(1)
Te(2)–M(1)–Cl(2)
Cl(1)–M(1)–Cl(1)[a]
Cl(1)–M(1)–Cl(2)
89.92(4)
176.5(1)
92.34(6)
87.66(6)
92.50(4)
87.50(4)
88.61(8)
91.57(9)
178.46(8)
180.0
180.0
89.9(1)
[a] Symmetry operation: –x + 1/2, –y + 1/2, –z + 1.
Figure 2. Molecular structure of trans-[MCl2{Te(CH2SiMe3)2}2]
[M = Pt (2t), Pd (3t)] indicating the numbering of atoms. The ther-
mal ellipsoids have been drawn at 50% probability level.
The molecular packing of 2c and 2t and 3t is shown in
trans-[PdCl2{Te(CH2SiMe3)2}2] (3t) is isomorphic with the Supporting Information (see Figure S2). Weak H···Cl
the platinum complex 2t. The Pd–Te and Pd–Cl bond hydrogen bonds [2.665(1)–2.994(1) Å] link cis-[PtCl2-
lengths in 3t are 2.5910(5) and 2.302(1) Å, respectively, in {Te(CH2SiMe3)2}2] (2c) complexes into a two-dimensional
agreement with those reported for other telluroether com- quasi-planar network. Only van der Waals interactions are
plexes of palladium {see, for instance trans-[PdCl2{Te- found between the layers. In the case of trans-
(C6H2Me3)2}2] [Pd–Te 2.569(3)–2.596(4) Å, Pd–Cl 2.270(4)– [MCl2{Te(CH2SiMe3)2}2] [M = Pt (2t), Pd (3t)] the respec-
2.318(4) Å][29] and trans-[PdCl2{Te(CH2)4}2] [Pd–Te tive H···Cl hydrogen bonds of 2.765(2)–2.882(2) Å and
2.593(2)–2.593(2) Å, Pd–Cl 2.319(3)–2.326(3) Å][23]}. The 2.761(1)–2.827(1) Å result in the formation of skewed
higher trans influence of tellurium to chlorine can again be stacks like in trans-[MCl2{Se(Me)CH2QMe3)2}],[12]
deduced for all trans complexes by comparing these bond [MCl2(SeMeTh)2] (M = Pd, Pt; Q = Si, Ge; Th = 2-thienyl
lengths to those in cis-[PdCl2(TeMeR)2] [R = 2-thienyl C4H3S),[13] and [PdCl2(SeEt2)2].[17] By contrast to cis-
(C4H3S) or 2-furyl (C4H3O)] [Pd–Te 2.538(1)–2.546(1) and [PdCl2(TeMeR)2] (R = thienyl, furyl C4H3O),[13] trans-[PtI2-
2.530(1) Å, and Pd–Cl 2.351(1)–2.352(1) and 2.356(1)– (TeMePh)2]),[14] cis-[PdCl2{meso-(TeC6H4OMe-4)2CH2}],[30]
2.359(1) Å, for the (methyl)(2-thienyl)tellane and (2-furyl)- and cis-[PdBr2{meso-(PhTe)2(CH2)3}],[31] no Te···Cl interac-
(methyl)tellane complexes, respectively].[13]
tions were found in 2c or in 2t and 3t.
Figure 3. Molecular structure of [Pt2Cl4{µ-Te(CH2SiMe3)2}{Te(CH2SiMe3)2}2] (4) indicating the numbering of atoms. The thermal ellip-
soids have been drawn at 50% probability level.
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Platinum and Palladium Complexes of Bis(trimethylsilylmethyl)tellane
Figure 4. Molecular structure of [Pd2(µ-Cl)2Cl2{Te(CH2SiMe3)2}2] (5) indicating the numbering of atoms. The thermal ellipsoids have
been drawn at 50% probability level.
Dinuclear Complexes
Table 2. Selected bond lengths [Å] and angles [°] of [Pt2Cl4-
{Te(CH2SiMe3)2}3] (4) and [Pd2(µ-Cl)2Cl2{Te(CH2SiMe3)2}2] (5).
The molecular structures indicating the numbering of the
atoms are shown in Figures 3 and 4 for [Pt2Cl4{µ-Te(CH2-
[Pt2Cl4{Te(CH2SiMe3)2}3] (4)
SiMe3)2}{Te(CH2SiMe3)2}2] (4) and [Pd2(µ-Cl)2Cl2{Te-
(CH2SiMe3)2}2] (5), respectively. Their selected bond pa-
rameters are presented in Table 2.
The two slightly distorted square-planar coordination
environments of the Pt(1) and Pt(2) centers in 4 are linked
by a bridging Te(CH2SiMe3)2 ligand and further coordi-
nated by two chlorido ligands and one terminal Te(CH2Si-
Me3)2 ligand. Interestingly, one platinum center exhibits a
cis-Cl,cis-Te(CH2SiMe3)2 coordination environment, while
the other shows trans-Cl,trans-Te(CH2SiMe3)2 coordination
Pt(1)–Te(1)
Pt(1)–Te(3)
Pt(1)–Cl(11)
Pt(1)–Cl(12)
Te(1)–Pt(1)–Te(3)
Te(1)–Pt(1)–Cl(11)
Te(1)–Pt(1)–Cl(12)
Te(3)–Pt(1)–Cl(11)
Te(3)–Pt(1)–Cl(12)
Cl(11)–Pt(1)–Cl(12)
Pt(1)–Te(3)–Pt(2)
2.5581(7) Pt(2)–Te(2)
2.5728(7) Pt(2)–Te(3)
2.5436(8)
2.518(1)
2.344(2)
2.313(2)
93.79(3)
179.69(6)
89.65(7)
86.52(6)
173.57(7)
90.06(9)
2.293(2)
2.303(2)
179.2(2)
87.07(6)
93.20(5)
92.13(6)
87.61(5)
Pt(2)–Cl(21)
Pt(2)–Cl(22)
Te(2)–Pt(2)–Te(3)
Te(2)–Pt(2)–Cl(21)
Te(2)–Pt(2)–Cl(22)
Te(3)–Pt(2)–Cl(21)
Te(3)–Pt(2)–Cl(22)
178.91(8) Cl(21)–Pt(2)–Cl(22)
125.29(3)
(see Figure 3). Both the co-existence of cis and trans envi- [Pd2(µ-Cl)2Cl2{Te(CH2SiMe3)2}2] (5)
ronments in the same dinuclear complex and the presence
of a bridging telluroether ligand are very rare. The only
previous examples of the latter are provided by polymeric
Pd(1)–Te(1)
2.506(1)
2.314(3)
2.431(3)
2.291(4)
2.511(1)
2.315(4)
2.433(3)
2.286(4)
93.23(9)
Pd(3)–Te(3)
2.503(2)
2.312(4)
2.419(4)
2.288(4)
2.506(1)
2.320(4)
2.431(4)
2.280(4)
92.9(1)
Pd(1)–Cl(11)
Pd(1)–Cl(11)[a]
Pd(1)–Cl(12)
Pd(2)–Te(2)
Pd(3)–Cl(31)
Pd(3)–Cl(31)[c]
Pd(3)–Cl(32)
Pd(4)–Te(4)
trans-[PtClTh{Te(Me)(Th)}2]n (Th
=
2-thienyl)[32] and
[CuCl(TeEt2)]n.[33]
Pd(2)–Cl(21)
Pd(2)–Cl(21)[b]
Pd(2)–Cl(22)
Te(1)–Pd(1)–Cl(11)
Pd(4)–Cl(41)
Pd(4)–Cl(41)[d]
Pd(4)–Cl(42)
Te(3)–Pd(13)–Cl(31)
The geometries and bond parameters involving the cis-
and trans-Pt centers are very similar to those observed for
2c and 2t and are consistent with the relative magnitudes
of the trans influence. The Pt(1)–Te(1) [2.5581(7) Å] and
Pt(1)–Te(3) [2.5728(7) Å] bonds are longer than the Pt(2)–
Te(2) [2.5436(8) Å] and Pt(2)–Te(3) [2.518(1) Å] bonds,
while Pt(1)–Cl(11) of 2.293(2) Å and Pt(1)–Cl(12) of
2.303(2) Å are shorter than Pt(2)–Cl(21) of 2.344(2) Å and
Pt(2)–Cl(22) of 2.313(2) Å.
[Pd2(µ-Cl)2Cl2{Te(CH2SiMe3)2}2] (5) shows a coplanar
arrangement of the Cl(Te)PdCl2Pd(Te)Cl framework (see
Figure 4) with Pd–Te bond lengths of 2.503(1)–2.511(1) Å,
terminal Pd–Cl bond lengths of 2.280(4)–2.291(4) Å, and
pairs of asymmetrical bridging Pd–Cl bond lengths of
Te(1)–Pd(1)–Cl(11)[a] 178.6(1)
Te(31)–Pd(13)–Cl(31)[c] 177.2(1)
Te(1)–Pd(1)–Cl(12)
Cl(11)–Pd(1)–Cl(11)[a] 86.6(1)
Cl(11)–Pd(1)–Cl(12) 178.9(1)
Cl(11)[a]–Pd(1)–Cl(12) 94.5(1)
Te(2)–Pd(2)–Cl(21) 93.4(1)
Te(2)–Pd(2)–Cl(21)[b] 177.8(2)
Te(2)–Pd(2)–Cl(22) 85.8(1)
Cl(21)–Pd(2)–Cl(21)[b] 86.7(1)
Cl(21)–Pd(2)–Cl(22) 178.9(1)
Cl(21)[b]–Pd(2)–Cl(22) 94.1(1)
85.8(1)
Te(3)–Pd(3)–Cl(32)
Cl(31)–Pd(3)–Cl(31)[c]
Cl(31)–Pd(3)–Cl(32)
Cl(31)[c]–Pd(3)–Cl(32)
Te(4)–Pd(4)–Cl(41)
Te(4)–Pd(4)–Cl(41)[d]
Te(4)–Pd(4)–Cl(42)
86.2(1)
86.6(1)
178.8(1)
94.4(1)
91.9(1)
175.6(1)
86.7(1)
Cl(41)–Pd(4)–Cl(41)[d] 87.5(1)
Cl(41)–Pd(4)–Cl(42) 177.3(2)
Cl(41)[d]–Pd(4)–Cl(42) 94.1(1)
[a] Symmetry operation: –x + 2, –y, –z + 1. [b] Symmetry opera-
tion: –x + 1, –y + 1, –z + 1. [c] Symmetry operation: –x + 1, –y,
2.312(4)–2.320(4) Å and 2.419(4)–2.433(4) Å. This asym- –z + 2. [d] Symmetry operation: –x, –y + 1, –z + 2.
Eur. J. Inorg. Chem. 2008, 284–290
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287

L. Vigo, R. Oilunkaniemi, R. S. Laitinen
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Scheme 1.
metric bridging arrangement agrees well with many dinu- could be structurally characterized in the solid state by sin-
clear thioether complexes of palladium, as exemplified by gle-crystal X-ray crystallography.
those in [Pd(Me)(SMe2)(µ-Cl)2Pd(SMe2)(Me)][34] and
The corresponding reaction involving [PdCl2(NCPh)2]
[Pd{CH(COOMe)(CH2C6F5)}(tht)(µ-Cl)2Pd{CH(COOMe)- and Te(CH2SiMe3)2 (1) afforded only the trans isomer of
(CH2C6F5)}(tht)] (tht = tetrahydrothiophene)[35] that show [PdCl2{Te(CH2SiMe3)2}2] (3t).
the respective pairs of bridging Pd–Cl distances of 2.358(1)
and 2.498(1) Å, and 2.365(2) and 2.437(2) Å.
In addition to the mononuclear complexes, the reactions
of [MCl2(NCPh)2] (M = Pt, Pd) and Te(CH2SiMe3)2 re-
The packing of the dinuclear complexes 4 and 5 is shown sulted in the formation of dinuclear complexes [Pt2Cl4{µ-
in the Supporting Information (see Figure S3). Respective Te(CH2SiMe3)2}{Te(CH2SiMe3)2}2] (4) and [Pd2(µ-Cl)2Cl2-
weak H···Cl hydrogen bonds of 2.689(1)–2.963(1) Å and {Te(CH2SiMe3)2}2] (5). Their formation probably involves
2.797(3)–2.989(4) Å again link the complexes into skewed first the substitution of PhCN by Te(CH2SiMe3)2 followed
stacks or layers (4 and 5, respectively). Like in the case of by the condensation of the resulting mononuclear com-
mononuclear complexes 2c, 2t, and 3t, there are no Te···Cl plexes (see Scheme 1).
close contacts.
The dinuclear complexes were observed with an initial
ligand/metal molar ratio between 1:1 and 2:1. It is therefore
possible that the monosubstituted [MCl2(TeR2)(NCPh)] (M
= Pt, Pd) complexes are involved in their formation. We
note that the bridging telluroether ligand and the presence
of both cis-Cl and trans-Cl centers in 4 is virtually unprece-
dented. In case of palladium, the formation of 5 is easily
understood in similar terms. With an excess of the tellane
ligand, only mononuclear [MCl2(TeR2)2] complexes are
formed.
Conclusions
A
series of [bis(trimethylsilylmethyl)tellane]platinum
and -palladium complexes have been prepared from bis(tri-
methylsilylmethyl)tellane and bis(benzonitrile)dichlorido-
platinum and -palladium. When the ligand/metal ratio was
Ͼ2:1, the main products in both reactions were mononu-
clear [MCl2{Te(CH2SiMe3)2}2] (M = Pt, Pd) complexes.
The NMR spectroscopic information indicates that the iso-
mer distribution of the platinum complex depends on the
initial molar ratio of the reactants. When [PtCl2(NCPh)2] Experimental Section
was used in excess, cis-[PtCl2{Te(CH2SiMe3)2}2] (2c) was
General: (Chloromethyl)trimethylsilane (Aldrich), tellurium (pow-
the main isomer. Upon increasing the initial ligand/metal
molar ratio, the relative amount of the trans isomer in-
creased. The stoichiometric reaction afforded approxi-
mately equal amounts of the cis and trans isomers. Increase
of the initial amount of the ligand even further mainly
der; Johnson Matthey Chemicals), NaBH4 (Riedel-de Haën),
NaOH (Merck), CH3OH (Lab-Scan), MgSO4 (Fisher Scientific),
diethyl ether (Lab-Scan), benzene (Appli-Chem), n-hexane (Lab-
Scan) were commercially available and used without further purifi-
cation. [PtCl2(NCPh)2] and [PdCl2(NCPh)2] were prepared accord-
yielded trans-[PtCl2{Te(CH2SiMe3)2}2] (2t). Both isomers ing to the method of Kharasch et al.[36]
288 Eur. J. Inorg. Chem. 2008, 284–290
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Platinum and Palladium Complexes of Bis(trimethylsilylmethyl)tellane
NMR Spectroscopy: 1H, 13C{1H}, 125Te, 195Pt, and 29Si NMR spec-
tra were recorded with a Bruker DPX400 spectrometer operating
at 400.13, 100.61, 126.28, 85.66 and 79.49 MHz, respectively. The
typical spectral widths were 5.58, 20.16, 126.58, 100.00, and
found C 22.20, H 5.00. 125Te NMR (CDCl3, 25 °C): δ = 266
(1JPt–Te = 804 Hz; 2c), 292 (1JPt–Te = 469 Hz; 2t) ppm. 195Pt NMR
(CDCl3, 25 °C): δ = –4237 (1JPt–Te = 804 Hz, 2c), –3707 (1JPt–Te
=
463 Hz, 2t) ppm. The effect of the initial molar ratio of the reac-
14.37 kHz. The pulse widths were 4.50, 4.00, 10.00, 10.00, and tants on the product distribution was explored by carrying out the
10.00 µs. 1H pulse delay was 0.10 s, that for 13C{1H} was 3.00 s, for
125Te 1.60 s for 195Pt 0.4 s, and for 29Si 8.00 s. 1H accumulations
contained ca. 30000 transients, those for 13C{1H} 50000 transients,
those for 125Te 30000 transients, those for 195Pt 50000 transients,
and those for 29Si 23000 transients. Tetramethylsilane was used as
reaction in a similar fashion as described above but keeping the
molar amount of [PtCl2(NCPh)2] virtually constant and varying
that of 1: Molar ratio 1:1: [PtCl2(NCPh)2] (0.255 g; 0.540 mmol),
Te(CH2SiMe3)2 (0.163 g; 0.540 mmol). Molar ratio 1:1.5:
[PtCl2(NCPh)2] (0.238 g; 0.504 mmol), Te(CH2SiMe3)2 (0.230 g;
0.755 mmol). Molar ratio 1:2: [PtCl2(NCPh)2] (0.237 g;
0.502 mmol), Te(CH2SiMe3)2 (0.304 g; 1.003 mmol). Molar ratio
1:3: [PtCl2(NCPh)2] (0.253 g; 0.536 mmol), Te(CH2SiMe3)2
(0.483 g; 1.602 mmol).
1
an internal standard for H and 13C{1H}, and as an external stan-
dard for 29Si. A saturated solution of Ph2Te2 in CDCl3 and a D2O
solution of [PtCl6]2– were used as external standards for 125Te and
195Pt chemical shift, respectively. All the spectra were recorded in
2
CDCl3 which served as an internal H lock. Chemical shifts (ppm)
Preparation of [PdCl2{Te(CH2SiMe3)2}2] (3t): The preparation of
[PdCl2{Te(CH2SiMe3)2}2] was carried out in a similar fashion by
treating [PdCl2(NCPh)2] (0.197 g; 0.514 mmol) with an excess of 1
(0.388 g; 1.285 mmol). Orange solid (yield: 0.301 g; 75%).
C16H44Cl2PdSi4Te2 (781.39): calcd. C 24.59, H 5.68; found C 24.13,
H 5.61. 125Te NMR (CDCl3, 25 °C): δ = 306 (3t) ppm. As with
the platinum complexes, the effect of the initial molar ratio of the
reactants on the isomerism was investigated by varying their rela-
tive amounts: Molar ratio 1:1: [PdCl2(NCPh)2] (0.205 g;
0.534 mmol), Te(CH2SiMe3)2 (0.161 g; 0.534 mmol). Molar ratio
1:1.5: [PdCl2(NCPh)2] (0.193 g; 0.502 mmol), Te(CH2SiMe3)2
(0.228 g; 0.754 mmol). Molar ratio 1:2: [PdCl2(NCPh)2] (0.195 g;
0.509 mmol), Te(CH2SiMe3)2 (0.308 g; 1.018 mmol).
are reported relative to Me4Si, and neat Me2Te [δ(Me2Te) =
δ(Ph2Te2) + 422].[37]
Preparation of Te(CH2SiMe3)2 (1): The preparation of 1 was car-
ried out, as described previously.[26] The product was obtained as
1
pale orange liquid. H NMR (CDCl3, 25 °C): δ = 1.71 (m, CH2),
0.07 (br. m, SiMe3) ppm. 13C NMR (CDCl3, 25 °C): δ = –3.5 (s,
SiMe3), –15.8 (s, CH2) ppm. 125Te NMR (CDCl3, 25 °C): δ = 26
(s) ppm. 29Si NMR (CDCl3, 25 °C): δ = 2.8 (s) ppm.
Preparation of [PtCl2{Te(CH2SiMe3)2}2] (2c and 2t): [PtCl2(NC-
Ph)2] (0.236 g; 0.498 mmol) was dissolved in 5 mL of benzene, and
an excess of 1 (0.375 g; 1.240 mmol) was added to the resulting
solution. The reaction mixture was stirred at room temp. for 24 h
and subsequently concentrated by evaporation of the solvent. The
raw product was filtered, washed with a 1:1 mixture of methanol/
n-hexane and recrystallized from CH2Cl2. Pale yellow solid (yield:
0.336 g; 78%). C16H44Cl2PtSi4Te2 (870.05): calcd. C 22.09, H 5.10;
Isolation of [Pt2Cl4{µ-Te(CH2SiMe3)2}{Te(CH2SiMe3)2}2] (4):
Upon crystallization of the 1:1.5 and 1:2 reaction mixtures from
CH2Cl2, a small crop of crystals of the novel dimeric complex 4
was obtained in addition to 2c and 2t. The habit of the crystals
Table 3. Crystal data and details of the structure determinations of cis-[PtCl2{Te(CH2SiMe3)2}2] (2c), trans-[PtCl2{Te(CH2SiMe3)2}2] (2t),
trans-[PdCl2{Te(CH2SiMe3)2}2] (3t), [Pt2Cl4{Te(CH2SiMe3)2}3] (4) and [Pd2(µ-Cl)2Cl2{Te(CH2SiMe3)2}2] (5).
2c
2t
3t
4
5
Empirical formula
Formula mass
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C16H44Cl2PtSi4Te2 C8H22ClPt0.5Si2Te C8H22ClPd0.5Si2Te C25.5H67.5Cl4Pt2Si6Te3 C16H44Cl4Pd2Si4Te2
870.06
orthorhombic
Pbca
435.03
monoclinic
C2/c
390.69
monoclinic
C2/c
1457.61
triclinic
P1
958.67
triclinic
¯
¯
P1
12.452(5)
22.462(5)
22.991(5)
23.770(5)
6.529(1)
20.008(4)
23.809(5)
6.513(1)
20.003(4)
12.029(2)
13.509(3)
17.383(4)
75.68(3)
79.85(3)
70.65(3)
2568.5(9)
2
12.330(3)
12.635(3)
22.457(5)
83.62(3)
87.81(3)
89.81(3)
3474(1)
4
α [°]
β [°]
93.75(3)
93.74(3)
γ [°]
V [Å3]
6431(3)
8
3098 (1)
8
3095(1)
8
Z
F(000)
3296
1.797
6.460
1648
1.865
6.704
1520
1.677
2.777
1369
1.885
7.474
1840
1.833
3.132
0.15ϫ0.15ϫ0.10
2.51–25.00
10898
10898
9136
Dcalcd. [gcm–3]
µ (Mo-Kα) [mm–1]
Crystal size [mm]
θ range [°]
No. reflns. collected
No. unique reflns.
No. observed reflns.
0.30ϫ0.10ϫ0.05 0.20ϫ0.10ϫ0.07 0.30ϫ0.12ϫ0.05 0.20ϫ0.15ϫ0.12
3.51–26.00
20678
5945
4397
3.80–26.00
11185
3011
1.71–26.00
6826
2813
2.62–26.00
33361
9878
2704
2642
9094
No. of parameters/restraints 239/0
121/0
118/0
383/2
509/0
0.0812
0.0851
0.2165
0.0986
0.2292
1.084
2.780/–1.989
Rint
0.1070
0.0651
0.0586
0.0450
0.1225
0.0517
0.1250
1.230
0.0816
0.0473
0.1301
0.0568
0.1550
1.147
0.0576
0.0457
0.1259
0.0496
0.1294
1.039
R1 [IՆ2σ(I)][a]
wR2 [IՆ2σ(I)][a]
R1 (all data)[a]
wR2 (all data)[a]
Goodness-of-fit on F2
∆ρmax/min [eÅ–3]
0.1675
0.0920
0.1941
1.014
2.692/–2.056
2.693/–2.383
1.598/–1.994
3.742/–2.113
2
2 2
[a]R1 = Σ||Fo| – |Fc||/Σ|Fo|, wR2 = [Σw(Fo – Fc ) /ΣwFo4]1/2.
Eur. J. Inorg. Chem. 2008, 284–290
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
289

L. Vigo, R. Oilunkaniemi, R. S. Laitinen
FULL PAPER
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the X-ray analysis. The amount obtained was, however, not suf-
ficient for more detailed bulk analysis.
Preparation of [Pd2(µ-Cl)2Cl2{Te(CH2SiMe3)2}2] (5): The equi-
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(5)
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19.27, H 4.29. 125Te NMR (CDCl3, 25 °C): δ = 501 (5) ppm.
X-ray Crystallography: Diffraction data of 2c, 2t, 3t, 4, and 5 were
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ite-monochromated Mo-Kα radiation (λ = 0.71073 Å). Crystallo-
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matrix least-squares refinement of the non-hydrogen atoms with
anisotropic thermal parameters, the hydrogen atoms were placed in
calculated positions in methyl groups (C–H 0.98 Å) and in the CH2
groups (C–H 0.99 Å). The scattering factors for the neutral atoms
were those incorporated with the programs. CCDC-656720 to
-656724 for 2c, 2t, 3t, 4, and 5 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
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Acknowledgments
Financial support of the Academy of Finland and the Finnish Cul-
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Received: August 9, 2007
Published Online: November 8, 2007
290
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Eur. J. Inorg. Chem. 2008, 284–290