Thioether-functionalized n-heterocyclic carbenes: Mono-and bis-(S, C NHC) palladium complexes, catalytic C-C coupling, and characterization of a unique Ag4I4(S, C NHC)2 planar cluster

Article abstract of DOI:10.1021/om100500y

We report a one-step synthesis for new N-aryl-N′-thioether imidazolium salts that are precursors to (S,C_NHC) ligands in N-heterocyclic carbene (NHC) complexes. The crystal structure of the N-(2,6-diisopropylphenyl)-N′-ethyl-(ethyl)-sulfide imid

Full text of DOI:10.1021/om100500y

5614 Organometallics 2010, 29, 5614–5626
DOI: 10.1021/om100500y
Thioether-Functionalized N-Heterocyclic Carbenes: Mono- and Bis-(S,CNHC
Palladium Complexes, Catalytic C-C Coupling, and Characterization of a
Unique Ag4I4(S,CNHC)2 Planar Cluster†
)
Christophe Fliedel and Pierre Braunstein*
ꢀ
Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), Universite de Strasbourg,
4 Rue Blaise Pascal, F-67081 Strasbourg Cedex, France
Received May 21, 2010
We report a one-step synthesis for new N-aryl-N0-thioether imidazolium salts that are precursors to
(S,CNHC) ligands in N-heterocyclic carbene (NHC) complexes. The crystal structure of the N-(2,6-
diisopropylphenyl)-N0-ethyl-(ethyl)-sulfide imidazolium hexafluorophosphate 8 HPF6 was determined
by X-ray diffraction and revealed H-bonding interactions between the PF6 anion and, in particular, the
3
imidazolium 2-H proton. The corresponding Ag(I) NHC complexes 1 AgX-8 AgX were synthesized and
3
3
fully characterized. An unprecedented planar, centrosymmetric cluster, [Ag4(μ3-I)2(μ2-I)2(μ2-S,CNHC)2]
[5 (AgI)2]2, was obtained in which two functional carbene ligands bridge two edges of a silver rectangle.
3
With the N-alkyl-N0-thioether ligands, [PdCl2(S,CNHC)2] complexes were prepared by two different
routes: the usual transmetalation reaction involving the Ag(I) NHC reagent or a stepwise sequence
involving deprotonation of the imidazolium function in zwitterionic intermediates where the thioether
function is bound to the Pd(II) center. The crystal structures of two representative complexes, 10 and 12,
with an ethyl- or a phenyl-thioether function, respectively, coordinated to the Pd(II) center, have
been determined by X-ray diffraction and confirmed their mononuclear structure. In the neutral complexes
trans-[PdCl2(CNHC)2] (17-20) the thioether group is not coordinated to the metal center, as also
confirmed by the crystal structure determination by X-ray diffraction of the bis-NHC Pd(II) dichloro
complex 18, which also established the trans-anti arrangement of the ligands. The first examples of bis-
chelated dicationic palladium(II) complexes with thioether-functionalized NHCs, [Pd(S,CNHC)2][BF4]2
(21-24), are reported, which were selectively obtained with a cis arrangement of the ligands. The Pd(II)
complexes 9-24 were evaluated in Suzuki-Miyaura cross-coupling reactions under various conditions,
and a higher catalytic activity was observed for the complexes in which the sulfur atom is coordinated to
the metal center.
Introduction
carbene,2 the synthesis of various silver-NHC complexes,3
and the report of their use as carbene transfer reagents.4
Metal-NHC complexes have already found many applica-
tions in homogeneous catalysis.5 NHCs are often used as
phosphine alternatives owing to their better stability toward
oxidation and the formation of more stable metal com-
plexes.6 For cross-coupling reactions, strong σ-donor ligands
are necessary and the NHCs are the only class of ligands able to
challenge the long-used tertiary phosphines.7 Although the
association of NHCs with palladium(II) precursors has been
extensively studied in catalysis8 and NHC-Pd complexes com-
pared to phosphine-Pd catalysts,9 the use of well-defined NHC-
Pd(II) complexes as precatalysts for cross-coupling reactions
remains underdeveloped.10
N-Heterocyclic carbenes (NHCs) have attracted increas-
ing attention in organometallic chemistry since the pioneer-
ing work of Lappert,1 the report of the first stable free
† Part of the Dietmar Seyferth Festschrift. Dedicated to Prof. Dietmar
Seyferth for his outstanding career dedicated to all aspects of organometallic
chemistry: research, teaching, and publishing.
*Corresponding author. E-mail: braunstein@unistra.fr. Fax: þ33
368 851 322. Tel: þ33 368 851 308.
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r
pubs.acs.org/Organometallics
Published on Web 08/24/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 21, 2010 5615
Chart 1. Examples of (a) Single-Atom-Bridged Bis(CNHC),12o,q (b) Phenylene-Bridged Bis(CNHC),12n (c) N-,13g (d) O-,14e and
(e) P,CNHC15j Metal Complexes
The number of bis- and, more generally, polydentate
NHC-containing ligands has grown very rapidly.11 Varying
the nature of the linker between the donor functions and/or
the nature of the latter allows the creation of diversified
families of ligands. Examples of complexes containing two
carbene donors linked through a single atom or a pyridine or
phenylene backbone have been described (Chart 1, a and b).12
The synthesis of functional NHCs associating a carbene ligand
with a chemically different donor function has given rise to the
15
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Chem. Commun. 2010, 46, 324. (b) Kaufhold, O.; Stasch, A.; Pape, T.; Hepp,
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formation of N-,13 O-,14 and P,CNHC metal complexes
(Chart 1, c-e). These complexes rapidly showed great potential
in homogeneous catalysis.5f,8a,16 The chelating ability of these
ligands resulted in the formation of highly stable complexes with
a strong σ-donor function (NHC) and a more labile one, which
could result in a hemilabile behavior of the resulting systems in
solution.17 In turn, this could lead to the temporary dissociation
of the heteroatom donor from the metal during a catalytic cycle,
allowing the coordination of a substrate, its metal-assisted
transformation, and, after product elimination, stabilizing re-
coordination of this function.
Although the presence of a sulfur atom in the side chain
attached to nitrogen has revealed to be beneficial for some cata-
lytic reactions, e.g., catalytic Mizoroki-Heck coupling, ketone
hydrosilylation, or allylic substitution reactions,18,19 only a few
S,CNHC metal complexes have been described until now. Ex-
amples of mono(thioether) imidazolium18 and bis(thioether)
imidazolium salts19 and S,CNHC complexes obtained by oxida-
tive addition of a carbon sulfur bond across a zerovalent metal
precursor have been reported (Chart 2).20
€
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We recently reported an atom-efficient, one-step, and solvent-
free synthesis of new S,CNHC precursors bearing a thio-
ether function on a nitrogen atom, together with their Ag(I)
and Pd(II) complexes.18e In light of preliminary catalytic results
obtained with the latter, we decided to extend our investigations
on this ligand class. Here, we report the synthesis of mono-
carbene chelate complexes [PdCl2(S,CNHC)] by transmetalation
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5616 Organometallics, Vol. 29, No. 21, 2010
Fliedel and Braunstein
Chart 2. Examples of (a) Chelate S,CNHC18e and (b) Pincer
S,CNHC,S19a Palladium(II) Complexes
Scheme 1. Synthesis of the Carbene Precursors
Figure 1. View of the molecular structure of 8 HPF6. Only the
3
hydrogen atoms involved in H-bonding are shown for clarity.
Ellipsoids are represented at the 50% probability level. Selected
˚
bond lengths (A), bond angles (deg), and torsion angles (deg):
C1-N1 1.319(3), C1-N2 1.328(3), C1-H1 0.95(2), H1-F4
2.200(2), C10-F2 3.527(5), C11-F3 3.340(1), C11-F4 3.460(1),
C22-F1 3.421(3), N1-C1-N2 109.24(19), N1-C4-C5 110.4(2),
C14-C13-N2 117.5(2), C1-N1-C4-C5 105.9(3), C1-N2-
C12-C13 81.4(3).
resonances of the NCN carbons between 137.2 and 137.8 ppm
were also affected. Whereas the corresponding bromide salt
5 HBr has been previously described,18h its synthesis involved
3
first that of the N-(2-bromoethyl)-N0-(2,4,6-trimethylphenyl)-
imidazolium bromide, in two steps, with an overall yield of
60%.21
reaction or by an alternative pathway involving zwitterionic
intermediates where the functional imidazolium ligand is first
coordinated to the metal though its thioether function and then
deprotonated at the imidazolium site by a weak base. We also
prepared bis-carbene complexes [PdCl2(CNHC)2] in which the
sulfur atom remains uncoordinated and C,S-bis-chelated di-
cationic species [Pd(S,CNHC)2][BF4]2, attractive for catalysis
owing to a potentially easily accessible vacant coordination site
produced by displacement of the sulfur donors. Since we could
not isolate the corresponding free carbenes, their thione deriva-
tives were prepared in order to show that the imidazolium salts
can be deprotonated by an external base. We then extended
this family of ligands to aryl thioether imidazolium salts to
modify the physical properties, solubility, and steric and electro-
nic characteristics of the resulting complexes. The corresponding
silver(I) complexes were synthesized, and the structure of a
unique [Ag4I4(S,CNHC)2] planar cluster is reported.
Reaction of the N-(2,6-diisopropylphenyl)-substituted imida-
zolium iodides with excess KPF6 at room temperature in
CH2Cl2 for 2 days resulted in their quantitative conversion to
the hexafluorophosphate salts 6 HPF6 and 8 HPF6. Consistent
3
3
with the anion exchange, an upfield shift was observed in their
1H NMR spectra for the 2-H resonances at 9.04 and 8.68 ppm
and in the 13C{1H} NMR spectra for the NCN carbons at 136.0
and 135.1 ppm, respectively. Single crystals of 8 HPF6 suitable
3
for X-ray diffraction studies were obtained by slow diffusion of
pentane into a saturated dichloromethane solution of 8 HPF6.
3
Its molecular structure is depicted in Figure 1. The aromatic
substituent at N2 is almost orthogonal to the NCN ring, the
angle between the 2,6-diisopropylphenyl and the imidazole rings
being 84.2°. The steric constraints are also minimized on the N1
side with a torsion angle C1-N1-C4-C5 of 105.9° and an
angle between the N1-C4-C5 plane and the imidazole ring of
70.0°. In the solid state, nonclassical hydrogen bonds exist
between the imidazolium and the PF6 counteranion. The stron-
gest one is between the acidic hydrogen H1 and the fluorine
Results and Discussion
Preparation of the Carbene Precursors. The N-alkyl-N0-
thioether imidazolium chlorides 1 HCl-4 HCl were prepared
3
3
˚
as described previously (Scheme 1).18e This procedure was
slightly modified for the preparation of the N-aryl-N0-thioether
imidazolium salts. The solid reagents, N-(2,4,6-trimethylphe-
nyl)- and N-(2,6-diisopropylphenyl)imidazole, were dissolved in
toluene, and addition of excess NaI favored the reaction with
2-chloroethyl ethylsulfide or 2-chloroethyl phenylsulfide. This
reaction resulted at the same time in a counteranion exchange,
which afforded the N-aryl-N0-thioether imidazolium iodides
atom F4 (2.20 A). The orientation of the phenyl ring from the
thioether moiety is probably also influenced by the three non-
classical H bonds between their hydrogen atoms H11 and H12
and the fluorine atoms F2, F3, and F4 (see values below).
Synthesis of the Thione Derivatives. The free carbenes 1-4
could not be isolated, owing to their low stability in solution,
but addition of sulfur to the reaction mixture yielded the corres-
ponding thiones 1 S-4 S, respectively, which could be isolated
3
3
and characterized (Scheme 2). Deprotonation of the imida-
zolium salts was established by the disappearance of the 2-H
5 HI-8 HI(Scheme1). Thisanionexchangeandtheelectronic
3
3
effect of the aryl substituents resulted in an upfield shift for the
2-H protons of 5 HI-8 HI between 9.26 and 9.78 ppm com-
3
3
pared to 1 HCl-4 HCl, for which the 2-H proton signal
(21) Wolf, J.; Labande, A.; Natella, M.; Daran, J.-C.; Poli, R. J. Mol.
Catal. A 2009, 259, 205.
3
3
appears between 10.36 and 10.51 ppm. The 13C{1H} NMR

Article
Organometallics, Vol. 29, No. 21, 2010 5617
Scheme 2. Synthesis of the Thione Derivatives of the NHC,
1 S-4 S
3
3
Scheme 3. Two Pathways for the Synthesis of [PdCl2(S,CNHC)]
Complexesa
Figure 2. (a) View of the molecular structure of [5 (AgI)2]2.
Hydrogen atoms are omitted for clarity. Ellipsoids are repre-
˚
sented at the 30% probability level. Selected bond lengths (A)
and bond angles (deg): Ag1-C1 2.128(1), Ag2-S1 2.552(3),
Ag1-Ag2 3.219(2), Ag1-Ag2i 2.9657(18), Ag1-I1 2.8259(17),
Ag1-I22.790(2), Ag2-I12.8826(19), Ag2-I2i 2.8423(18), Ag1-
I1i 2.953(2), C1-Ag1-I1 128.7(2), C1-Ag1-I2 122.4(2), I1-
Ag1-I2 108.07(5), S1-Ag2-I1 121.42(6), S1-Ag2-I1i 110.92(6),
S1-Ag2-I2i 109.74(7), Ag1 -Ag2-Ag1i 110.43(5). (b) Simpli-
fied view of the Ag4I4 core. Color code: gray, silver; pink, iodine.
3
a Conditions: (a): 1 equiv Ag2O, CH2Cl2, RT; (b): 1 equiv [PdCl2-
(cod)], CH2Cl2, RT; (c): 1 equiv [PdCl2(cod)], CH2Cl2, RT; (d): 1 equiv
Cs2CO3, MeCN, 60 °C.
imidazolium 1H NMR resonance. The 13C{1H} NMR spectra
of these thiones showed a typical downfield shift for the NCN
carbon signal between 161.6 and 162.1 ppm. The ESI-MS
spectra and the elemental analysis confirmed the CdS bond
formation. By comparison with the IR spectra of the corres-
ponding imidazolium salts, the CdS stretching vibration of the
partiallypreventdeprotonationforstericreasons.Inthefollow-
ing experiments involving the [AgX(NHC)] complexes, these
will be prepared in situ and used as transmetalation agents,
after filtration of their solution through a Celite pad to
remove unreacted silver oxide.
thiones 1 S-4 S is tentatively assigned to an intense absorption
3
3
in the region 1225-1230 cm-1
.
Synthesis of the Silver(I) Complexes. Formation of NHC
metal complexes by transmetalation from the corresponding
silver carbene complexes represents a well-known procedure.4
Before using these complexes in situ as transmetalation
reagents, we attempted to isolate and fully characterize them.
Reaction of the imidazolium salts, in CH2Cl2 at room temp-
erature, with excess Ag2O as a base resulted in the formation
of the corresponding Ag(I) NHC complexes formulated as
Slow diffusion of pentane into a saturated dichloro-
methane solution obtained by reaction of 5 HI and Ag2O
3
afforded colorless single crystals suitable for X-ray diffrac-
tion and a brownish oil. The crystals were found to corres-
pond to the formulation [Ag2(μ3-I)(μ2-I)(μ2-S,CNHC)]2. Its
solid-state molecular structure is depicted in Figure 2 and
exhibits an unexpected arrangement (Scheme 4).
1 AgCl-4 AgCl on the basis of mass spectrometry data
3
3
(Scheme 3).18e The same procedure was followed for the
formation of 5 AgI-8 AgI. The success of the reaction is
Although the coordination chemistry of NHCs toward
silver salts is very diversified,3a,22 the centrosymmetric struc-
ture of this polynuclear complex shows an unprecedented
planar Ag4 core with two bridging S,CNHC ligands. The two
chemically different Ag atoms have different coordination
geometries: Ag1 has a slightly distorted trigonal-planar
3
3
shown by the disappearance of the 2-H proton resonance in
the 1H NMR spectra of the complexes. Their formation was
also established by a characteristic downfield shift of the
NCN 13C{1H} NMR resonance between 181.5 and 183.3
ppm. The reaction of Ag2O with the hexafluorophosphate
imidazolium salts did not lead to complete conversion. This
could be due to strong interactions between the 2-H imida-
zolium proton and the counteranion (Figure 1), which may
(22) (a) Lin, I. J. B.; Vasam, C. S. Coord. Chem. Rev. 2007, 251, 642.
(b) Garrison, J. C.; Youngs, W. J. Chem. Rev. 2005, 105, 3978.

5618 Organometallics, Vol. 29, No. 21, 2010
Fliedel and Braunstein
a
Scheme 4. Preparation of the Planar Cluster [5 (AgI)2]2
3
under mild conditions and to avoid the use of Ag(I) inter-
mediates, which may interfere in subsequent catalytic reactions.
Addition of [PdCl2(cod)] to a stirred dichloromethane solu-
tion of the imidazolium salts 1 HCl-4 HCl led to the dis-
3
3
placement of the cod ligand and coordination of the thio-
ether function. The pure product precipitated rapidly, afford-
ing complexes 13-16 in good yields after washing the solids
with pentane to eliminate the traces of cod. The coordination
sphere of the palladium atom comprised three Cl and one
thioether ligand, and the resulting zwitterionic structure was
confirmed spectroscopically. The characteristic signal for the
2H-imidazolium proton is present in the 1H NMR spectra of all
complexes between 9.10 and 9.23 ppm. The ESI-MS spec-
tra reveal as most intense peaks the [M þ Na]þ and [M - Cl]þ
ions, with the expected isotopic distributions, which rules out a
a Conditions: (a): 1 equiv Ag2O, CH2Cl2, RT.
geometry formed by C1, I1, and I2, whereas Ag2 has a slightly
distorted tetrahedral coordination geometry formed by S1, I1,
I10, and I20. The angles involving the capping iodides deviate sig-
nificantly from those in a regular coordination environment [see,
e.g., C1-Ag1-I1=128.7(2)° and S1-Ag2-I1=121.42(6)°].
The distances between the silver atoms supported by the bridging
S,CNHC ligand are significantly longer than that between the
silver atoms doubly bridged by iodide ligands; Ag1-Ag2 =
hypothetical ion-pair structure of general formula [(L H)2-
3
(PdCl4)] (L = carbene 1-4). The far-infrared spectra of the
complexes 13-16 showed a typical pattern for the ν(Pd-Cl)
vibrations of a LPdCl3 fragment.25 The elemental analyses of
these complexes were also in good agreement with the calcu-
lated values. Owing to the low solubility of these compounds in
organic solvents, characteristic for highly polar compounds, no
13C{1H} NMR spectra could be recorded for complexes 13-15
and the NCN signal was not observed in the spectrum of 16.
These Pd(II) complexes are not air-, light-, or moisture-sensi-
tive and can be stored for weeks without any trace of degrada-
tion, in contrast to most silver NHC complexes. This pathway
thus allows a stepwise and easy access to catalyst precursors,
which could be immediately employed in catalysis. We thus
examined the formation of chelate species by deprotonation of
the zwitterionic complexes 13-16 for3hwithoneequivalentof
the weak base Cs2CO3 in refluxing acetonitrile. This afforded
the desired complexes of general formula [PdCl2(S,CNHC)]
(9-12), respectively. All the spectroscopic data confirm their
mononuclear structure and the cis arrangement of the ligands.
Broad signals were observed in the 1H NMR spectra, owing to
the formation of a stereogenic sulfur atom after its coordina-
tion to palladium.18e The values of the ν(Pd-Cl) stretching
0
˚
˚
3.219(2) A and Ag1-Ag2 =2.9657(18) A, respectively. The two
iodide ligands have different coordination modes, since I2 acts as
a μ2-bridging ligand, supporting the Ag1 Ag20 interaction,
3 3 3
whereas I1 is μ3-capping three metal centers (Ag1, Ag2, and
Ag20). The Ag Ag distances [2.9657(18) and 3.219(2) A] are
˚
3 3 3
notably shorter than those in the only other structurally char-
acterized related Ag4I4 cluster (to the best of our knowledge),
which contains phosphine ligands [Ag Ag 3.0953(13) and
3 3 3
23
˚
˚
3.4378(21) A]. The carbene-silver bond length of 2.128(1) A is
in agreement with literature values, and the S-Ag distance is
slightly longer than those observed for other donor groups (such
as N- or P-donors) in functional NHC complexes.24 The far-
infrared spectrum of crystalline [5 (AgI)2]2 exhibits strong
3
absorptions at 236 and 154 cm-1, which are tentatively assigned
to the stretching vibrations of the μ2-bridging and μ3-capping
iodides, respectively.
The Ag/I/NHC stoichiometry of 2:2:1 in [5 (AgI)2]2 differs
3
vibration in the far-infrared spectrum (ca. 312 and 295 cm-1
)
from that of the reagents (1:1:1). This observation explains why
the yield of the formation of this cluster was less than 50%.
When the reaction was carried out with an additional equiva-
are also consistent with a cis arrangement of the chlorides.19a,26
Using a stronger base, such as KOt-Bu, on a similar system,
Wolf et al. observed the formation of a dinuclear species, in
which the ligand acted as a C,S-bridge between two metal
centers.18h The solid-state molecular structures of complexes 10
and 12 are depicted in Figures 3 and 4, respectively. They are
very similar, and in each case, the complexes adopt a distorted
square-planar geometry around the palladium centers. The
ligands form a C,S chelate with a bite angle of 83.19(11)° and
88.99(13)° for 10 and 12, respectively. The higher trans influ-
ence of the carbene ligands compared to the sulfur is illustrated
by longer Pd(1)-Cl(1) bonds compared to Pd(1)-Cl(2). The
six-membered palladacycle formed by the metal and the chelate
ligand adopts a boat-like conformation, in which C(4) and
Pd(1) are on the same side of the C1-N2(1)-C5-S1 plane.
Due to the short side chain (two methylene groups) and
coordination of the sulfur atom, the angles between the imida-
zole ring and the palladium coordination plane deviate from
the electronically preferred 90°, with values of 56.8(3)° and
53.1(9)° for 10 and 12, respectively.
lent of AgI, the cluster [5 (AgI)2]2 was formed in 93% yield
3
(Scheme 4).
Synthesis of the Mono-NHC Palladium(II) Complexes. Two
routes were investigated for the formation of [PdCl2(S,CNHC)]
complexes.
Route A: Transmetalation Reaction (Scheme 3, a and b).
This classical method involves the in situ synthesis of the cor-
responding silver complexes 1 AgCl-4 AgCl and their reac-
3
3
tion with the palladium precursor, [PdCl2(cod)] (cod =1,5-
cyclooctadiene), in a 1:1 ratio, to give the desired chelate com-
plexes [PdCl2(S,CNHC)] (9-12), as reported recently for 9.18e
Route B: In Situ Deprotonation of a Zwitterionic Inter-
mediate (Scheme 3, c and d). Our motivation to explore an
alternative route was to establish the possible beneficial effect
of the presence of the sulfur atom on complex formation
(23) (a) Teo, B.-K.; Calabrese, J. C. Inorg. Chem. 1976, 15, 2474.
(b) Teo, B.-K.; Calabrese, J. C. J. Am. Chem. Soc. 1975, 97, 1256.
(24) See e.g. (for poly-NHCs): (a) Rit, A.; Pape, T.; Hahn, F. E.
J. Am. Chem. Soc. 2010, 132, 4572. (b) Hahn, F. E.; Radloff, C.; Pape, T.;
Hepp, A. Chem.—Eur. J. 2008, 14, 10900. (For N-): (c) Li, F.; Bai, S.;
Hor, T. S. A. Organometallics 2008, 27, 672. (d) Tulloch, A. A. D.;
Danopoulos, A. A.; Winston, S.; Kleinhenz, S.; Easthamb, G. J. Chem.
Soc., Dalton Trans. 2000, 4499. (For P-): Raynal, M.; Liu, X.; Pattacini, R.;
(25) (a) Clark, R. J. H.; Williams, C. S. Inorg. Chem. 1965, 4, 350.
ꢀ
ꢀ
(b) Bencze, E.; Papai, I.; Mink, J.; Goggin, P. L. J. Organomet. Chem. 1999,
584, 118.
(26) Pfeffer, M.; Braunstein, P.; Dehand, J. Spectrochim. Acta 1974,
30A, 341.
ꢀ
Vallee, C.; Olivier-Bourbigou, H.; Braunstein, P. Dalton Trans. 2009, 7288.

Article
Organometallics, Vol. 29, No. 21, 2010 5619
Synthesis of the Bis-NHC Palladium(II) Complexes. Since
NHC ligands are known to be strong donor ligands that
rarely dissociate from the metal, the presence of two NHC
ligands on the palladium center could lead to attractive
species for catalytic applications. Two types of bis-carbene
palladium complexes were synthesized in the course of this
work.
Starting from the corresponding silver complexes synthe-
sized in situ, reaction with [PdCl2(cod)] in a 2:1 ratio afforded
the bis-carbene palladium dichloride complexes of general
formula [PdCl2(L)2], 17 -20 (Scheme 5, a). Only one isomer
was formed during the reaction, and the NMR spectra of
these complexes showed only one set of signals for the
ligands. The sharp 1H NMR signals are consistent with
dangling lateral side chains bonded to the nitrogen atoms.
At this stage, it is reasonable to suggest that the trans isomer
is formed, and the value of the ν(Pd-Cl) stretching vibration
around 340 cm-1 is in accordance with this hypothesis.26 The
trans-anti arrangement was confirmed by the solid-state
X-ray structures of 1718e and 18 (Figure 5). The palladium
atom occupies a center of symmetry for the molecule, and the
square-planar coordination geometry around the palladium
center is only slightly distorted (C1-Pd1-Cl1 90.3(1)°).
A second type of bis-NHC palladium complexes was synthe-
Figure 3. View of the molecular structure of 10. Hydrogen
atoms are omitted for clarity. Ellipsoids are represented at the
˚
50% probability level. Selected bond lengths (A) and bond
angles (deg): Pd1-C1 1.989(4), Pd1-S1 2.2955(11), Pd1-Cl1
2.3631(10), Pd1-Cl2 2.3317(10), C1-N1 1.333(5), C1-N2
1.342(5), C1-Pd1-S1 83.19(11), C1-Pd1-Cl2 90.99(11), S1-
Pd1-Cl1 93.30(4), N1-C1-N2 106.8(3).
sized, starting from the silver complexes 1 AgCl-4 AgCl.
3
3
Reaction of 0.5 equiv of [Pd(NCMe)4][BF4]2 with the corres-
ponding silver complex generated in situ, at room temperature
in dichloromethane, afforded the dicationic, bis-chelated
palladium(II) complexes 21-24, of general formula [Pd(S,
CNHC)2][BF4]2. Their formation results from the easy displace-
ment of the palladium-bound acetonitrile ligands, which was
confirmed by 1H NMR spectroscopy. Only a few examples of
bis-chelated dicationic Pd complexes, with donor-functiona-
lized NHC ligands, have been described, and they showed
interesting catalytic activities in coupling reactions.13a,27 Bis-
chelated dicationic [Pd(N,CNHC)2]X2 with N representing a
picoline donor moiety were recently reported and have been
studied in Heck-type coupling reactions.13a,g To the best of our
knowledge, no example with thioether side chains was reported.
Such complexes could offer advantages for catalytic applica-
tions: they bear two strong ligands known to be efficient in
homogeneous catalysis and have two coordination sites readily
accessible by displacement of the soft sulfur ligands. These
properties could lead to catalysts active for Suzuki-Miyaura
couplings under very mild, room-temperature conditions.28
Like in the case of the monochelate palladium dichloride
complexes, the sulfur atom becomes a stereogenic center upon
coordination to the metal center, and this gives rise to a
broadening of the 1H NMR resonances. This is in accordance
with the bis-chelation of the ligands in the dicationic complexes,
whereas sharp signals were observed for the dichloro-bis-NHC
complexes. The broadening is due to a more rigid structure of
the side chain, in contrast to the situation in the dichloro
complexes. The carbenic carbons of 21-24 resonate, in the
13C{1H} NMR, between 155.1 and 157.8 ppm, strongly upfield
shifted compared to the neutral trans complexes, e.g., 170.1
ppm for 20, and to reported [Pd(N,CNHC)2][BF4]2 complexes
Figure 4. View of the molecular structure of 12. Hydrogen
atoms are omitted for clarity. Ellipsoids are represented at the
˚
50% probability level. Selected bond lengths (A) and bond
angles (deg): Pd1-C1 1.978(4), Pd1-S1 2.2858(12), Pd1-Cl1
2.3709(12), Pd1-Cl2 2.3301(12), C1-N1 1.340(5), C1-N2
1.346(5), C1-Pd1-S1 88.99(13), C1-Pd1-Cl2 91.89(13), S1-
Pd1-Cl1 86.55(4), N1-C1-N2 106.0(4).
By using the procedure of route B (Scheme 3, c and d),
which has only limited precedents,18h,19a we found that the
presence of a thioether moiety exerts a favorable anchimeric
assistance for the selective formation of [PdCl2(S,CNHC)]
chelate complexes without the constraints of a transmetala-
tion reaction. Another beneficial aspect of this method
compared to transmetalation is that the catalyst precursor
can be formed directly in situ and immediately engaged in a
catalytic process with no silver contamination. This has been
(27) (a) Zhang, X.; Xia, Q.; Chen, W. Dalton Trans. 2009, 7045.
(b) Zhang, X.; Xi, Z.; Liu, A.; Chen, W. Organometallics 2008, 27, 4401.
(c) Ye, J.; Chen, W.; Wang, D. Dalton Trans. 2008, 4015. (d) Chiu, P. L.; Lai,
C.-L.; Chang, C.-F.; Hu, C.-H.; Lee, H. M. Organometallics 2005, 24, 6169.
(e) McGuinness, D. S.; Cavell, K. J. Organometallics 2000, 19, 741.
(28) Nishikata, T.; Abela, A. R.; Huang, S.; Lipshutz, B. H. J. Am.
Chem. Soc. 2010, 132, 4978, and references therein.
tested with 1 HCl to form in situ complex 9 in the catalytic
3
studies described below.

5620 Organometallics, Vol. 29, No. 21, 2010
Scheme 5. Synthetic Pathways for the Synthesis of Bis-NHC Palladium(II) Complexesa
Fliedel and Braunstein
a (a) 1/2 equiv [PdCl2(cod)], CH2Cl2, RT ; (b) 1/2 equiv [Pd(NCMe)4][BF4]2, CH2Cl2, RT.
Scheme 6. Typical Procedure for the Catalytic Reactions
Table 1. Catalytic Activities for Mono-NHC Palladium
Complexesa
complex
yield (%)
complex
yield (%)
9
88
94
86
91
13
14
15
16
62,a 86b
71,a 95b
51,a 87b
47,a 91b
10
11
12
a Yields determined by GC. Reaction conditions: cat. 2 mol %, base
Cs2CO3, solvent DMSO, temp 60 °C, reaction time 2 h. b Reaction time 5 h.
common solvent for this reaction. The conversions to
4-methyl-biphenyl observed with the chelate complexes
9-12 are nearly quantitative. The best yields, 94% and
91%, were obtained for the complexes bearing an N-n-Bu
substituent, 10 and 12, respectively. The presence of this side
chain probably induces a higher solubility of the precursors.
The conversions observed with the zwitterionic compounds
13-16 were lower than those obtained with the correspond-
ing chelate species.
Figure 5. View of the molecular structure of 18. Only one of the
two analogous crystallographically independent molecules is
depicted. Hydrogen atoms are omitted for clarity. Ellipsoids are
represented at the 50% probability level. Selected bond lengths
˚
(A) and bond angles (deg): Pd1-C1 2.025(4), Pd1-Cl1
The reaction mixtures did not turn dark with formation of
potentially active Pd(0) species, in contrast to the case of the
NHC complexes 9-12. Runs performed with 13-16 for 5 h
reaction time led to similar yields to those in the case of the
chelated precatalysts ((2%). Assuming that the zwitterionic
compounds 13-16 are not the direct catalyst precursors, but
are first transformed during the induction period to the
corresponding neutral chelate species 9-12, a catalytic reac-
tion starting from complex 13 was run for 6 h and a plot of
the yield as a function of time is shown in Figure 6.
During the first 2 h, almost no conversion was observed,
this time being necessary for the formation of the carbene
complex 9 by deprotonation of 13 by the slight excess of base
present in the reaction mixture. During the next 3 h, the
conversion was similar to that observed when starting from
complex 9 (Figure 6). This experiment indicates the stepwise
formation of the precatalyst in the reactor by reaction of the
imidazolium salt, the palladium precursor, and the base used
for the catalytic reaction. It could be interesting to extend
this procedure to other metal complexes such as Ni(II) or
Rh(I) and to donor functions like amines or phosphines,
which are involved in diverse catalytic reactions. With the
2.3094(10), C1-N1 1.351(5), C1-N2 1.349(5), C1-Pd1-Cl1
90.29(11), N1-C1-N2 105.3(3).
(N-donor from a picoline moiety in a cis arrangement) between
167.3 and 166.1 ppm,13a,g but more downfield than a [Pd(N,
CNHC)2][PF6]2 complex (150.9 ppm).27d This very large upfield
shift results from the cis arrangement of the carbene donors, the
coordination of the thioether function, and the formally di-
cationic charge on the Pd center. The latter will increase the
donation from the carbenic carbon, which is illustrated by the
value of their chemical shift. We could thus show that selective
formation of trans-[PdCl2(CNHC)2] and cis-[Pd(S,CNHC)2]-
[BF4]2 complexes is possible starting from readily accessible
Ag(NHC) complexes.
Catalytic Studies. The palladium complexes 9-24 were
evaluated in Suzuki-Miyaura cross-coupling reactions. The
complexes were first tested using the procedure described in
Scheme 6, and then for the most interesting complexes, the
conditions were varied. The results obtained with the mono-
NHC complexes 9-16 are reported in Table 1.
The choice of DMSO as a solvent resulted from the
low solubility of these complexes in dioxane, which is the

Article
Organometallics, Vol. 29, No. 21, 2010 5621
Table 4. Catalytic Activities of Complexes 10 and 22 under
Modified Reaction Conditionsa
complex
yieldb (%)
complex
yieldc (%)
10
22
54
58
10
22
30
38
a Yields determined by GC. Reaction conditions: base Cs2CO3,
solvent DMSO, temp 60 °C, reaction time 2 h. b Catalyst 1 mol %,
X = Br. c Catalyst 2 mol %, X = Cl.
Figure 6. Evolution of the conversion to 4-methyl-biphenyl as a
function of time in the Suzuki-Miyaura cross-coupling reaction
starting from zwitterionic complex 13.
divided by two. It is more difficult to achieve the cross-coupling
reaction with chlorinated than with brominated substrates,29
which explains the drop of the conversion from 94% (10) and
98% (22) to 30% and 38% for 10 and 22, respectively.
Table 2. Solvent and Base Effects on the Catalysis Reaction with
Complex 10a
solvent
yieldb (%)
base
yieldc (%)
Conclusion
dioxane
DMSO
DMF
toluene
water
80
94
57
71
0
NaOAc
NaCO3
K2CO3
NEt3
36
74
70
29
91
The scope of a procedure recently described for the synthesis
of new functionalized N-heterocyclic carbene precursors bear-
ing as side arms a bulky aromatic group and a thioether func-
tion able to coordinate to a metal center has been extended and
could gain wider applicability.18e,19a Thus, linking an imidazo-
lium cation to a metal center via its functional side chain tends
to favor its subsequent deprotonation and formation of the
carbene-metal bond. Four different types of palladium(II)
complexes bearing thioether-NHC ligands were obtained, and
the ligand was acting as a S,CNHC chelate in complexes 9-12
and 21-24. However, an unprecedented planar Ag4I4 cluster
has been structurally characterized in which the S,CNHC ligand
bridges two Ag centers with different coordination geometries.
Among the Pd(II) complexes that were evaluated in Suzuki-
Miyaura cross-coupling reactions, a higher catalytic activity
was observed for those in which the sulfur atom is coordinated
to the metal center. It will be interesting to see whether similar
observations apply to other catalytic reactions.
Cs2CO3
a Yields determined by GC. Reaction conditions: cat. 2 mol %, base,
solvent, temp 60 °C, time 2 h. b Base Cs2CO3. c Solvent DMSO.
Table 3. Catalytic Activities for Bis-NHC Palladium Complexesa
complex
yield (%)
complex
yield (%)
17
18
19
20
74
68
72
79
21
22
23
24
90
98
91
96
a Yields determined by GC. Reaction conditions: cat. 2 mol %, base
Cs2CO3, solvent DMSO, temp 60 °C, reaction time 2 h.
most efficient catalyst precursor, complex 10, different sol-
vents and bases were used to optimize the reaction conditions
(Table 2). As expected, the highly polar solvent DMSO was
the best for these complexes (94%), but we also observed a
good activity with toluene as solvent (71%). DMF, another
polar solvent, was also tested, but no better activity than in
the case of DMSO was observed. Four inorganic bases were
tested with this complex, and carbonates were the most
efficient, Cs2CO3 being the best (91%). The organic base
NEt3 gave rise to less than 30% conversion (Table 2).
The bis-NHC palladium complexes 17-24 were also
evaluated in Suzuki-Miyaura cross-coupling reactions,
and the results obtained are reported in Table 3. The catalytic
tests were performed under the conditions optimized for the
mono-NHC palladium complexes (see above). The dichlo-
ride compounds led to relatively good yields, between 68%
(18) and 79% (20). Finally, with the dicationic, bis-chelated
species 21-24, the best activities of all the palladium com-
plexes synthesized in this work were observed, especially with
complex 22, which gave 98% conversion.
Experimental Section
General Procedures. All operations were carried out using
standard Schlenk techniques under inert atmosphere. Solvents
were purified and dried under nitrogen by conventional methods.
˚
d6-DMSO was degassed and stored over 4 A molecular sieves.
˚
CD2Cl2, CDCl3, andCD3CN were dried over 4 A molecular sieves,
degassed by freeze-pump-thaw cycles, and stored under argon.
NMR spectra were recorded at room temperature on a Bruker
AVANCE 300 spectrometer (1H, 300 MHz; 13C, 75.47 MHz; 31P,
121.49 MHz; and 19F, 282.38 MHz) and referenced using the
residual proton solvent (1H) or solvent (13C) resonance. Assign-
ments are based on 1H, 1H-COSY, 1H, 13C-HMQC, and 1H, 13C-
HMBC experiments. Chemical shifts (δ) are given in ppm. IR
spectra were recorded in the region 4000-100 cm-1 on a Nicolet
6700 FT-IR spectrometer (ATR mode, SMART ORBIT acces-
sory, Diamond crystal). Elemental analyses were performed by the
ꢀ
“Service de Microanalyses”, Universite de Strasbourg, and by the
“Service Central d’Analyse”, USR-59/CNRS, Solaize. Electro-
spray mass spectra (ESI-MS) were recorded on a microTOF
(Bruker Daltonics, Bremen, Germany) instrument using nitrogen
Inviewof theseresults, further experiments wereperformed
with the best catalysts. These were tested first with a lower
catalyst loading and then with p-chlorotoluene as substrate.
The results of these catalytic runs are reported in Table 4.
With complexes 10 and 22, a decrease of the conversion was
observed when 1 mol % precatalyst was used instead of 2 mol %,
as in the previous experiments; however, the conversion was not
(29) (a) Diebolt, O.; Braunstein, P.; Nolan, S. P.; Cazin, C. S. J. Chem.
Commun. 2008, 3190. (b) Bedford, R. B.; Cazin, C. S. J.; Holder, D. Coord.
Chem. Rev. 2004, 248, 2283. (c) Littke, A. F.; Fu, G. C. Angew. Chem., Int.
Ed. 2002, 41, 4176. (d) Grushin, V. V.; Alper, H. Chem. Rev. 1994, 94, 1047.

5622 Organometallics, Vol. 29, No. 21, 2010
Fliedel and Braunstein
as drying agent and nebulizing gas, and Maldi-TOF analyses were
carried out on a Bruker AutiflexII TOF/TOF (Bruker Daltonics,
Bremen, Germany), using dithranol (1,8,9-trihydroxyanthracene)
as a matrix. Gas chromatographic analyses were performed on a
Thermoquest GC8000 Top series gas chromatograph using a HP
Pona column (50 m, 0.2 mm diameter, 0.5 μm film thickness). The
imidazolium salts 1 HCl to 4 HCl18e and the complexes [PdCl2-
124.42 (CH meta-Diip), 128.67 (C ipso-Diip), 131.68 (CH para-
Diip), 137.75 (NCN), 145.28 (C ortho-Diip). MS (ESI): m/z
317.2 [M - I]þ.
7 HI: R = 2,4,6-trimethylphenyl; R0 = phenyl. The same
3
procedure was used with N-(2,4,6-trimethylphenyl)imidazole
(5.07 g, 27.20 mmol), 2-chloroethyl phenylsulfide (4.00 mL,
4.70 g, 27.20 mmol), and sodium iodide (8.15 g, 54.39 mmol).
The product was isolated as a yellow solid. Yield: 85%. Anal.
Calcd for C20H23IN2S (450.38): C, 53.34; H, 5.15; N, 6.22.
3
3
(cod)],30 [Pd(NCMe)4][BF4]2,31 1 AgCl-4 AgCl,18e 9,18e and
3
3
1718e were prepared according to literature methods. All other
reagents were used as received from commercial suppliers.
Abbreviations: Mes = 2,4,6-trimethylphenyl; Diip = 2,6-diiso-
propylphenyl; KHMDS = potassium hexamethyldisilazane.
Synthesis of N-(R)-N0-Ethyl-(R0)-sulfide Imidazolium Iodides
5 HI-8 HI. These compounds are known to be very hygro-
Found: C, 51.73; H, 5.27; N, 4.82. FTIR: νmax(solid)/cm-1
:
3145br, 3096w, 3050br, 2947w, 1627w, 1604w, 1581w, 1561m,
1547s, 1479m, 1446s, 1436s, 1380w, 1364w, 1346w, 1324w,
1280w, 1247w, 1200vs, 1154s, 1109w, 1087w, 1067s, 1035m,
1023m, 967w, 935w, 865s, 821m, 782m, 743vs, 703m, 692vs,
663vs 1H NMR (CDCl3, 300 MHz) δ: 2.05 (6H, s, 2 CH3 ortho-
3
3
scopic, and the elemental analyses always afforded carbon and
nitrogen percentages lower than calculated values.
3
Mes), 2.32 (3H, s, CH3 para-Mes), 3.62 (2H, t, J = 6.0 Hz,
5 HI: R = 2,4,6-trimethylphenyl; R0 = ethyl. Pure N-(2,4,6-
NCH2CH2S), 4.90 (2H, t, 3J = 6.0 Hz, NCH2CH2S), 6.98 (2H,
s, 2H meta-Mes), 7.17 (1H, pseudo t, 3J = 4J = 1.8 Hz, CHd
CHNCH2), 7.20-7.37 (5H, m, H aromatics), 8.01 (1H, pseudo t,
3
trimethylphenyl)imidazole (2.00 g, 10.74 mmol), 2-chloroethyl
ethylsulfide (1.25 mL, 1.34 g, 10.74 mmol), and sodium iodide
(3.22 g, 21.48 mmol) were placed in a Schlenk tube equipped
with a magnetic stirrer, and toluene was added. The mixture was
refluxed for 2 h and then allowed to cool to room temperature.
During heating, the colorless mixture turned light brown. After
cooling, the mixture was filtered to eliminate the excess of salts
formed and/or remaining. The volatiles were evaporated under
reduced pressure, and the brown oil was washed with dry diethyl
ether (2 ꢀ 40 mL) and dried under vacuum. The residue was puri-
fied by precipitation from a saturated MeOH solution in cold Et2O.
The product was isolated as a yellow oil. Yield: 84%. Anal. Calcd
for C16H23IN2S (402.34): C, 47.76; H, 5.76; N, 6.96. Found: C,
45.51; H, 6.13; N, 5.76. FTIR: νmax(oil)/cm-1: 3118sh, 3057br,
2968br, 2920br, 2866sh, 1606w, 1561m, 1545s, 1484m, 1446s,
1376w, 1329w, 1263w, 1199vs, 1157s, 1104w, 1067s, 1034m,
968w, 934w, 854s, 750m, 730sh, 698w, 666s. 1H NMR (CDCl3, 300
MHz) δ: 1.24 (3H, t, 3J = 7.2 Hz, SCH2CH3), 2.10 (6H, s, 2 CH3
ortho-Mes), 2.34 (3H, s, CH3 para-Mes), 2.68 (2H, q, 3J = 7.2 Hz,
SCH2CH3), 3.13 (2H, t, 3J = 6.0 Hz, NCH2CH2S), 4.95 (2H, t, 3J
= 6.0 Hz, NCH2CH2S), 7.01 (2H, s, 2H meta-Mes), 7.18 (1H,
pseudo t, 3J = 4J = 1.8 Hz, CHdCHNCH2), 7.98 (1H, pseudo t,
4
4
3J = J = 1.8 Hz, MesNCHdCH), 9.69 (1H, t, J = 1.5 Hz,
NCHN). 13C{1H} NMR (CDCl3, 75.5 MHz) δ: 17.88 (2 CH3
ortho-Mes), 21.15 (CH3 para-Mes), 34.85 (NCH2CH2S), 49.25
(NCH2CH2S), 122.98, 123.34 (CHdCH), 127.32 (CH para-
phenyl), 129.64 (2 CH meta-phenyl), 129.90 (2 CH meta-Mes),
130.01 (2 CH ortho-phenyl), 130.44 (C ipso-Mes), 133.28 (C ipso-
phenyl), 134.32 (2 C ortho-Mes), 137.26 (NCN), 141.50 (C para-
Mes). MS (ESI): m/z 323.2 [M - I]þ.
8 HI: R = 2,6-diisopropylphenyl; R0 = phenyl. The same
3
procedure was used with N-(2,6-diisopropylphenyl)imidazole
(5.07 g, 27.20 mmol), 2-chloroethyl phenylsulfide (4.00 mL, 4.70
g, 27.20 mmol), and sodium iodide (8.15 g, 54.39 mmol). The
product was isolated as a yellow solid. Yield: 92%. Anal. Calcd
for C23H29IN2S (492.46): C, 56.10; H, 5.94; N, 5.69. Found: C,
55.01; H, 5.80; N, 4.46. FTIR: νmax(solid)/cm-1: 3148br, 3053br,
2967br, 2929br, 2871br, 1584w, 1562w, 1546w, 1459m, 1440w,
1420w, 1388w, 1367w, 1354sh, 1313w, 1264s, 1187m, 1103w,
1088sh, 1070w, 1059w, 1025w, 895w, 844s, 806m, 730vs, 700vs,
671s. 1H NMR (CDCl3, 300 MHz) δ: 1.19 (12H, 2 d, 3J = 6.9
3
Hz, 2 CH(CH3)2), 2.34 (2H, sept, J = 6.9 Hz, 2 CH(CH3)2),
4
4
3J = J = 1.8 Hz, MesNCHdCH), 9.78 (1H, t, J = 1.5 Hz,
NCHN). 13C{1H} NMR (CDCl3, 75.5 MHz) δ: 14.74 (SCH2CH3),
17.89 (2 CH3 ortho-Mes), 21.16 (CH3 para-Mes), 26.14
(SCH2CH3), 32.29 (NCH2CH2S), 49.71 (NCH2CH2S), 123.00,
123.65 (CHdCH), 129.92 (2 CH meta-Mes), 130.48 (C ipso-Mes),
134.40 (2 C ortho-Mes), 137.69 (NCN), 141.51 (C para-Mes). MS
(ESI): m/z 275.2 [M - I]þ.
3.62 (2H, t, 3J = 5.7 Hz, NCH2CH2S), 4.90 (2H, t, 3J = 5.7 Hz,
NCH2CH2S), 7.21 (1H, pseudo t, 3J = 4J = 1.8 Hz, CHd
CHNCH2), 7.25-7.33 (7H,m, 5H phenyl and 2H meta-Diip),
7.55 (1H, t, 3J = 7.8 Hz, H para-Diip), 8.03 (1H, pseudo t, 3J =
4J = 1.7 Hz, DiipNCHdCH), 9.26 (1H, t, 4J = 1.5 Hz, NCHN).
13C{1H} NMR (CDCl3, 75.5 MHz) δ: 24.41 (2 CHCH3), 28.69
(2 CHCH3), 34.96 (NCH2CH2S), 49.24 (NCH2CH2S), 124.17,
124.21 (CHdCH), 124.82 (2 CH meta-Diip), 127.46 (CH para-
phenyl), 129.72 (2 CH meta-phenyl), 129.81 (C ipso-Diip),
129.91 (2 CH ortho-phenyl), 132.16 (CH para-Diip), 133.00
(C ipso-phenyl), 137.19 (NCN), 145.52 (C ortho-Diip). MS (ESI):
m/z 365.2 [M - I]þ.
6 HI: R = 2,6-diisopropylphenyl; R0 = ethyl. The same
3
procedure was used with N-(2,6-diisopropylphenyl)imidazole
(5.07 g, 27.20 mmol), 2-chloroethyl ethylsulfide (4.00 mL, 4.70 g,
27.20 mmol), and sodium iodide (8.15 g, 54.39 mmol). The
product was isolated as a yellow oil. Yield: 81%. Anal. Calcd for
C19H29IN2S (444.42): C, 51.35; H, 6.58; N, 6.30. Found: C,
48.96; H, 6.62; N, 5.30. FTIR: νmax(oil)/cm-1: 3152br, 3071br,
2964br, 2929br, 2871br, 1592w, 1564m, 1547m, 1458m, 1414sh,
1387w, 1367m, 1315w, 1264w, 1245sh, 1190m, 1130sh, 1105m,
1071m, 1060m, 959w, 938w, 874sh, 829vs, 759s, 739s, 693m,
670s. 1H NMR (CDCl3, 300 MHz) δ: 0.82-0.99 (15H, 2d, 3J =
6.9 Hz, 2 CH(CH3)2, and t, 3J = 7.2 Hz, SCH2CH3,), 2.10 (2H,
General Procedure for the Anion Exchange.
6 HPF6: R = 2,6-diisopropylphenyl ; R0 = ethyl. The imidazo-
lium iodide 6 HI (0.200 g, 0.45 mmol) and solid KPF6 (0.414 g, 2.25
3
3
mmol) were mixed in CH2Cl2 and stirred for 2 days at room
temperature. Then the suspension was filtered through a Celite
pad, and the solvent was evaporated under reduced pressure to give
a yellow solid. Yield: 97%. Anal. Calcd for C19H29F6N2PS (462.48):
C, 49.34; H, 6.32; N, 6.06. Found: C, 48.96; H, 6.47; N, 6.24. FTIR:
3
3
sept, J = 6.6 Hz, 2 CH(CH3)2), 2.44 (2H, q, J = 7.4 Hz,
SCH2CH3), 2.89 (2H, t, 3J = 6.0 Hz, NCH2CH2S), 4.72 (2H, t,
3J = 6.0 Hz, NCH2CH2S), 7.02 (1H, pseudo t, 3J = 4J = 1.8 Hz,
CHdCHNCH2), 7.16 (2H, d, 3J = 8.1 Hz, 2H meta-Diip), 7.27
(1H, t, 3J = 8.1 Hz, H para-Diip), 8.28 (1H, pseudo t, 3J = 4J =
ν
max(solid)/cm-1: 3151br, 2966br, 2930br, 2872br, 2360br, 1626br,
1564m, 1548m, 1459m, 1388w, 1367w, 1315w, 1261w, 1216w,
1190m, 1104w, 1071w, 1060w, 911s, 837vs, 806sh, 757sh, 729vs,
669s. 1H NMR (CDCl3, 300 MHz) δ: 1.17 (12H, 2 d, 3J = 6.9 Hz, 2
CH(CH3)2), 1.22 (3H, t, 3J = 7.2 Hz, SCH2CH3), 2.35 (2H, sept, 3
J = 6.9 Hz, 2 CH(CH3)2), 2.62 (2H, q, 3J = 7.2 Hz, SCH2CH3),
3.06 (2H, t, 3J = 6.0 Hz, NCH2CH2S), 4.74 (2H, t, 3J = 6.0 Hz,
NCH2CH2S), 7.21 (1H, pseudo t, 3J = 4J = 1.8 Hz, CH=
CHNCH2), 7.30 (2H, d, 3J = 8.1 Hz, 2H meta-Diip), 7.53 (1H, t,
3J = 8.1 Hz, H para-Diip), 7.91 (1H, pseudo t, 3J = 4J = 1.8 Hz,
4
1.8 Hz, DiipNCHdCH), 9.76 (1H, t, J = 1.5 Hz, NCHN).
13C{1H} NMR (CDCl3, 75.5 MHz) δ: 14.41 (SCH2CH3), 24.00,
24.42 (2 CHCH3), 25.60 (SCH2CH3), 28.29 (2 CHCH3), 32.30
(NCH2CH2S), 48.56 (NCH2CH2S), 123.58, 124.02 (CHdCH),
(30) Drew, D.; Doyle, J. R. Inorg. Synth. 1972, 13, 47.
(31) Wayland, B. B.; Schrammz, R. F. Inorg. Chem. 1969, 8, 971.
4
DiipNCH=CH), 9.04 (1H, t, J = 1.5 Hz, NCHN). 13C{1H}

Article
Organometallics, Vol. 29, No. 21, 2010 5623
NMR (CDCl3, 75.5 MHz) δ: 14.55 (SCH2CH3), 24.22, 24.29
(2 CHCH3), 25.59 (SCH2CH3), 28.56 (2 CHCH3), 32.18 (NCH2-
CH2S), 49.23 (NCH2CH2S), 123.43, 124.53 (CHdCH), 124.69 (CH
meta-Diip), 129.89 (C ipso-Diip), 132.00 (CH para-Diip), 137.39
(NCN), 145.59(Cortho-Diip). 31P{1H} NMR (CDCl3, 121.5MHz)
4.20 (2H, t, 3J = 7.2 Hz, NCH2CH2S), 6.66 and 6.75 (2H, AB
3
spin system, J = 2.4 Hz, CHdCH). 13C{1H} NMR (CDCl3,
75.5 MHz) δ: 13.70 (CH3 butyl), 14.86 (SCH2CH3), 19.80
(NCH2CH2CH2CH3), 26.19 (SCH2CH3), 30.02 (NCH2CH2S),
30.96 (NCH2CH2CH2CH3), 47.63 (NCH2CH2CH2CH3), 47.92
(NCH2CH2S), 116.44, 117.44 (CHdCH), 161.56 (NCN). MS
(ESI): m/z 251.1 [M þ Li]þ.
1
δ: -142.9 (sept., JP, F = 711 Hz, PF6). 19F{1H} NMR (CDCl3,
282.4 MHz) δ:-72.5(d, 1JP, F = 711 Hz, PF6). MS(ESI):m/z317.2
[M - PF6]þ.
3 S: R = methyl; R0 = phenyl. The same procedure was used
3
8 HPF6: R = 2,6-diisopropylphenyl ; R0 = phenyl. The same
procedure was used with 8 HI (0.200 g, 0.41 mmol) and solid
with KHMDS (0.235 g, 1.18 mmol), 3 HCl (0.300 g, 1.18 mmol),
3
3
and S8 (0.151 g, 0.59 mmol). The product was isolated as an
orange solid. Yield: 78%. Anal. Calcd for C12H14N2S2 (250.38):
C, 57.56; H, 5.64; N, 11.19. Found: C, 57.22; H, 5.87; N, 10.71.
FTIR: νmax(solid)/cm-1: 3307br, 3162br, 2963br, 2924br, 2869br,
2178m, 1732w, 1625w, 1534m, 1439m, 1401s, 1333w, 1225m
(tentatively assigned to the CdS stretching vibration), 1186w,
1111vs, 1048w, 1017vs, 874w, 713w, 670sh, 654m. 1H NMR (CD-
Cl3, 300 MHz) δ: 3.38 (2H, t, 3J =6.6 Hz, NCH2CH2S), 3.57(3H,
s, NCH3), 4.22 (2H, t, 3J = 6.6 Hz, NCH2CH2S), 6.59 and 6.65
(2H, AB spin system, 3J = 2.4 Hz, CHdCH), 7.19-7.40 (5H, m,
H arom). 13C{1H} NMR (CDCl3, 75.5 MHz) δ: 31.63 (NCH2-
CH2S), 35.06 (NCH3), 47.53 (NCH2CH2S), 117.51, 117.72
(CHdCH), 126.40 (C para-phenyl), 129.10 (C meta-phenyl),
129.21 (C ortho-phenyl), 134.69 (C ipso-phenyl), 161.95 (NCN).
MS (ESI): m/z 290.1 [M þ K]þ.
3
KPF6 (0.374 g, 2.03 mmol). The product was isolated as a yellow
solid. Yield: 98%. Anal. Calcd for C23H29F6N2PS (510.17): C,
54.11; H, 5.73; N, 5.49. Found: C, 54.34; H, 5.40; N, 5.09. FTIR:
ν
max(solid)/cm-1: 3155br, 3103w, 2968br, 2929w, 2872br,
1634br, 1565w, 1553m, 1474m, 1455m, 1442w, 1408w, 1389w,
1366w, 1350w, 1306w, 1288w, 1278w, 1265w, 1245w, 1217w,
1191s, 1153w, 1106w, 1089w, 1073w, 1059w, 1037w, 1024w,
1005w, 961w, 940w, 927w, 915w, 875s, 841vs, 820vs, 758vs, 698s,
671v, 652m. 1H NMR (CDCl3, 300 MHz) δ: 1.16 (12H, 2 d, 3J =
6.9 Hz, 2 CH(CH3)2), 2.31 (2H, sept, 3J = 6.8 Hz, 2 CH(CH3)2),
3.50 (2H, t, 3J = 5.9 Hz, NCH2CH2S), 4.66 (2H, t, 3J = 5.8 Hz,
NCH2CH2S), 7.22-7.33 (8H,m, CHdCHNCH2, 5H phenyl
3
and 2H meta-Diip), 7.54 (1H, t, J = 7.8 Hz, H para-Diip),
7.79 (1H, pseudo t, 3J = 4J = 1.5 Hz, DiipNCHdCH), 8.68 (1H,
br s, NCHN). 13C{1H} NMR (CDCl3, 75.5 MHz) δ: 24.10, 24.36 (2
CHCH3), 28.59 (2 CHCH3), 34.56 (NCH2CH2S), 49.09 (NCH2-
CH2S), 123.88 (CHdCH), 124.73 (br, 2 CH meta-Diip and
CHdCH), 127.42 (CH para-phenyl), 129.68 (2 CH meta-phenyl),
129.84 (C ipso-Diip), 129.93 (2 CH ortho-phenyl), 132.07 (CH para-
Diip), 133.03 (C ipso-phenyl), 136.87 (NCN), 145.57 (C ortho-
Diip). 31P{1H} NMR (CDCl3, 121.5 MHz) δ: -143.1 (sept.,
1JP, F = 711 Hz, PF6). 19F{1H} NMR (CDCl3, 282.4 MHz) δ:
-72.4 (d, 1JP, F = 711 Hz, PF6). MS (ESI): m/z 365.2 [M - PF6]þ.
4 S: R = n-butyl; R0 = phenyl. The same procedure was used
3
with KHMDS (0.202 g, 1.01 mmol), 4 HCl (0.300 g, 1.01
3
mmol), and S8 (0.130 g, 0.51 mmol). The product was isolated
as an orange solid. Yield: 80%. Anal. Calcd for C15H20N2S2
(292.46): C, 61.60; H, 6.89; N, 9.58. Found: C, 61.36; H, 6.42; N,
10.01. FTIR: νmax(solid)/cm-1: 3133br, 3053br, 2957br, 2930br,
2871br, 1667w, 1582w, 1517w, 1480sh, 1439m, 1412s, 1380w,
1358w, 1327w, 1264w, 1230m (tentatively assigned to the CdS
stretching vibration), 1114m, 1087w, 1021m, 942w, 876w, 732vs,
690s, 674m. 1H NMR (CDCl3, 300 MHz) δ: 0.94 (3H, t, 3J = 7.5
Hz, CH3 butyl), 1.35 (2H, m, CH2CH3), 1.71 (2H, m, CH2CH2-
CH3), 3.37 (2H, t, 3J = 6.6 Hz, NCH2CH2S), 3.98 (2H, t, 3J =
7.5 Hz, NCH2CH2CH2), 4.22 (2H, t, 3J = 6.6 Hz, NCH2CH2S),
Synthesis of the Thiones 1 S-4 S.
3
3
1 S: R = methyl; R0 = ethyl. Solid KHMDS (0.289 g, 1.45
mmol) was added to a stirred suspension of 1 HCl (0.300 g, 1.45
3
3
mmol) and S8 (0.186 g, 0.73 mmol) in THF at room temperature.
After 2 h, the reaction mixture was filtered through a Celite pad
and the THF evaporated under reduced pressure. The residue was
washed with pentane (2 ꢀ 20 mL) and dried under vacuum. The
product was obtained as an orange solid. Yield: 72%. Anal. Calcd
for C8H14N2S2 (202.34): C, 47.49; H, 6.97; N, 13.84. Found: C,
47.09; H, 7.26; N, 13.73. FTIR: νmax(solid)/cm-1: 3159br, 3125br,
3093br, 2956br, 2926br, 2869br, 1666w, 1582w, 1567w, 1457s,
1438s, 1400vs, 1358m, 1332m, 1265w, 1227s (tentatively assigned
to the CdS stretching vibration), 1205sh, 1182s, 1133w, 1086w,
1061w, 1023w, 971w, 936w, 872w, 797sh, 739m, 708s, 691sh, 669vs
1H NMR (CDCl3, 300 MHz) δ: 1.26 (3H, t, 3J = 7.5 Hz, SCH2-
CH3), 2.57 (2H, q, 3J = 7.5 Hz, SCH2CH3), 2.92 (2H, t, 3J = 6.9
Hz, NCH2CH2S), 3.60 (3H, s, NCH3), 4.20 (2H, t, 3J = 6.9 Hz,
3
6.59 and 6.65 (2H, AB spin system, J = 2.4 Hz, CHdCH),
7.15-7.39 (5H, m, H arom). 13C{1H} NMR (CDCl3, 75.5 MHz)
δ: 13.72 (CH3), 19.83 (CH2CH3), 30.95 (NCH2CH2S), 31.67
(NCH2CH2CH2), 47.43 (NCH2CH2CH2), 47.62 (NCH2CH2S),
116.33, 117.75 (CHdCH), 125.52 (C para-phenyl), 129.11
(C meta-phenyl), 129.14 (C ortho-phenyl), 134.83 (C ipso-
phenyl), 161.60 (NCN). MS (ESI): m/z 332.2 [M þ K]þ.
Synthesis of the Silver Complexes 5 AgI-8 AgI.
03
3
5 AgI: R = 2,4,6-trimethylphenyl; R = ethyl. The imidazolium
3
iodide 5 HI (0.080 g, 0.199 mmol) was dissolved in dry CH2Cl2,
3
and solid Ag2O (0.046 g, 0.199 mmol) was added under nitrogen.
The reaction mixture was stirred for 2 h in the dark at room
temperature. Then the suspension was filtered through a Celite pad,
and the solvent was evaporated under reduced pressure to give the
product as a light-sensitive white solid. Yield: 88%. Anal. Calcd for
C16H22AgIN2S (509.20): C, 37.74; H, 4.35; N, 5.50. Found: C,
37.55; H, 4.52; N, 5.31. FTIR: νmax(solid)/cm-1: 3116br, 3086br,
2962m, 2914m, 2862br, 2733br, 1607w,1558w, 1545w, 1486m,
1444m, 1408m, 1375w, 1352w, 1300sh, 1259s, 1223m, 1200w,
1152w, 1088s, 1065s, 1015vs, 968sh, 934w, 851m, 797vs, 733vs,
684m, 667m. 1H NMR (CDCl3, 300 MHz) δ: 1.19 (3H, t, 3J = 7.4
Hz, SCH2CH3), 1.87 (6H, s, 2 CH3 ortho-Mes), 2.33 (3H, s, CH3
para-Mes), 2.46 (2H, q, 3J = 7.4 Hz, SCH2CH3), 2.95 (2H, t, 3J =
6.6 Hz, NCH2CH2S), 4.43 (2H, t, 3J = 6.3 Hz, NCH2CH2S), 6.88
and 7.42 (2H, AB spin system, 3J = 1.7 Hz, CH=CHNCH2 and
MesNCHdCH), 6.90 (2H, s, 2H meta-Mes). 13C{1H} NMR
(CDCl3, 75.5 MHz) δ: 14.89 (SCH2CH3), 17.77 (2 CH3 ortho-
Mes), 21.16 (CH3 para-Mes), 26.68 (SCH2CH3), 33.43 (NCH2-
CH2S), 51.61 (NCH2CH2S), 122.04, 122.33 (CHdCH), 129.22 (2
CH meta-Mes), 134.90 (2 C ortho-Mes), 135.58 (C ipso-Mes),
139.16 (C para-Mes), 183.26 (NCN). MS (ESI): m/z381.1 [M - I]þ.
3
NCH2CH2S), 6.67 and 6.75 (2H, AB spin system, J = 2.4 Hz,
CHdCH). 13C{1H} NMR (CDCl3, 75.5 MHz) δ: 14.85 (SCH2-
CH3), 26.19 (SCH2CH3), 30.06 (NCH2CH2S), 35.10 (NCH3),
48.01 (NCH2CH2S), 117.30, 117.49 (CHdCH), 162.09 (NCN).
MS (ESI): m/z 225.1 [M þ OLi]þ.
2 S: R = n-butyl; R0 = ethyl. The same procedure was used
3
with KHMDS (0.241 g, 1.21 mmol), 2 HCl (0.300 g, 1.21
3
mmol), and S8 (0.155 g, 0.60 mmol). The product was isolated
as an orange solid. Yield: 69%. Anal. Calcd for C11H20N2S2
(244.42): C, 54.05; H, 8.25; N, 11.46. Found: C, 53.68; H, 8.41;
N, 11.20. FTIR: νmax(solid)/cm-1: 3127br, 3094br, 2956br,
2928br, 2869br, 1734w, 1671m, 1582w, 1568w, 1520w, 1480sh,
1455sh, 1438s, 1411vs, 1358m, 1268br, 1229s (tentatively as-
signed to the CdS stretching vibration), 1207m, 1173m, 1117w,
1087w, 1067w, 1047w, 1024w, 876w, 740s, 712m, 691m, 672 m.
1H NMR (CDCl3, 300 MHz) δ: 0.93 (3H, t, 3J = 7.5 Hz, CH3
butyl), 1.24 (3H, t, 3J = 7.5 Hz, SCH2CH3), 1.36 (2H, m,
NCH2CH2CH2CH3), 1.73 (2H, m, NCH2CH2CH2CH3), 2.54
3
3
(2H, q, J = 7.5 Hz, SCH2CH3), 2.91 (2H, t, J = 6.9 Hz,
NCH2CH2S), 4.01 (2H, t, J = 7.5 Hz, NCH2CH2CH2CH3),
The silver cluster [5 (AgI)2]2 was synthesized using the same
3
3
procedure, with further addition of AgI (0.047 g, 0.199 mmol).

5624 Organometallics, Vol. 29, No. 21, 2010
Fliedel and Braunstein
1
This compound is poorly soluble in organic solvents. The H
NMR spectrum recorded shows the same pattern as that of
5 AgI. The ESI-MS spectrum shows a signal corresponding to
in the dark at room temperature. Then the suspension was
filtered through a Celite pad under nitrogen, and the resulting
clear solution was slowly added to a suspension of the desired
palladium precursor. A white solid precipitated rapidly. The
suspension was then filtered through Celite, and the solvent was
evaporated under reduced pressure. The resulting solid was then
washed with pentane (2ꢀ25 mL) and crystallized from a
dichloromethane/pentane solution.
3
[[5 (AgI)2]2 - I]þ in accordance with a structure being partially
3
retained in solution. MS (ESI): m/z 1487.5 [M - I]þ. Far FT-IR
ν
max(crystals)/cm-1: 236vs (μ2-I), 154vs (μ3-I).
6 AgI: R = 2,6-diisopropylphenyl; R0 = ethyl. The same
procedure was used with 6 HI (0.110 g, 0.25 mmol) and Ag2O
3
3
Route B: In Situ Deprotonation of a Zwitterionic Intermediate.
The zwitterionic precursor (see below complexes 13-16) and
Cs2CO3 were placed in a Schlenk tube under nitrogen, and
MeCN was added. The reaction mixture was heated at 60 °C for
3 h and then allowed to cool to room temperature. After
filtration through a Celite pad, the solvent was evaporated
under reduced pressure. The resulting solid was washed with
pentane (2 ꢀ 20 mL) and recrystallized from a dichloromethane/
pentane solution.
(0.057 g, 0.25 mmol). The product was isolated as a light-
sensitive white solid. Yield: 84%. Anal. Calcd for C19H28-
AgIN2S (551.28): C, 41.40; H, 5.12; N, 5.08. Found: C, 41.08; H,
5.26; N, 4.88. FTIR: νmax(solid)/cm-1: 2963m, 2928m, 2870br,
1460m, 1416w, 1386w, 1364w, 1305w, 1261m, 1219w, 1191w,
1105m, 1072m, 1059m, 1024m, 938w, 874sh, 853vs, 806s, 762m,
1
741m, 691w, 670w. H NMR (CDCl3, 300 MHz) δ: 0.92 and
1.06 (2 ꢀ 6H, 2 d, 3J = 6.6 Hz, 2 CH(CH3)2), 1.18 (3H, t, 3J =
7.3 Hz, SCH2CH3), 2.26 (2H, sept, 3J = 6.8 Hz, 2 CH(CH3)2),
2.49 (2H, q, 3J = 7.2 Hz, SCH2CH3), 2.96 (2H, br, NCH2CH2S),
4.31 (2H, br, NCH2CH2S), 6.95 and 7.43 (2H, AB spin system,
3J = 1.5 Hz, CHdCHNCH2 and DiipNCHdCH), 7.17 (2H, d,
3J = 7.8 Hz, 2H meta-Diip), 7.41 (1H, t, 3J = 7.8 Hz, H para-
Diip). 13C{1H} NMR (CDCl3, 75.5 MHz) δ: 14.84 (SCH2CH3),
24.04, 24.20 (2 CHCH3), 24.57 (SCH2CH3), 28.08 (2 CHCH3),
33.49 (NCH2CH2S), 51.38 (NCH2CH2S), 124.16, 124.61 (CHd
CH), 129.28 (C ipso-Diip), 130.41 (CH meta-Diip), 134.68 (CH
para-Diip), 145.82 (C ortho-Diip), 181.48 (NCN). MS (ESI): m/z
423.1 [M - I]þ.
Synthesis of 9: R = methyl; R0 = ethyl.
Route A: see ref 18d.
Route B: Zwitterion 13 (0.070 g, 0.18 mmol) and Cs2CO3
(0.059 g, 0.18 mmol). The product was isolated as a yellow solid.
Yield: 76%.
Synthesis of 10: R = n-butyl; R0 = ethyl.
Route A: 2 HCl (0.250 g, 1.00 mmol), Ag2O (0.233 g, 1.00
3
mmol), and [PdCl2(cod)] (0.287 g, 1.00 mmol). The product was
isolated as a yellow solid. Yield: 80%. Anal. Calcd for
C11H20Cl2N2PdS (389.68): C, 33.90; H, 5.17; N, 7.19. Found:
C, 33.32; H, 5.44; N, 6.87. FTIR: νmax(solid)/cm-1: 3162w,
3124w, 3097w, 3047w, 2958m, 2940m, 2930m, 2869w, 1581w,
1572w, 1550w, 1479w, 1460m, 1438m, 1420s, 1381w, 1354w,
1275m, 1231s, 1202w, 1158w, 1129w, 1107w, 1107w, 1087w,
1074w, 1022m, 960w, 895w, 869w, 833w, 826w, 799w, 758m,
735vs, 726vs, 704vs, 688vs, 669s, 312vs (νPd-Cl), 296vs (νPd-Cl).
1H NMR (CD2Cl2, 300 MHz) δ: 0.98 (3H, t, 3J = 7.5 Hz, CH3
butyl), 1.40 (5H, m, SCH2CH3 and NCH2CH2CH2CH3), 1.91
(2H, m, NCH2CH2CH2CH3), 2.55 (2H, br, SCH2CH3), 2.89
(2H, br, NCH2CH2S), 4.52 (4H, br, NCH2CH2S and NCH2-
CH2CH2CH3), 7.01 and 7.20 (2H, AB spin system, 3J = 1.8 Hz,
CHdCH). MS (ESI): m/z 355.0 [M - Cl]þ.
7 AgI: R = 2,4,6-trimethylphenyl; R0 = phenyl. The same
3
procedure was used with 7 HI (0.120 g, 0.27 mmol) and Ag2O
3
(0.062 g, 0.27 mmol). The product was isolated as a light-sensitive
white solid. Yield: 91%. Anal. Calcd for C20H22AgIN2S (557.24):
C, 43.11; H, 3.98; N, 5.03. Found: C, 42.73; H, 4.10; N, 4.88. FTIR:
ν
max(solid)/cm-1: 3150br, 2965m, 2929br, 2871br, 1583w, 1564w,
1549w, 1459m, 1440m, 1415w, 1387w, 1366w, 1309w, 1264w,
1217w, 1188m, 1105m, 1088w, 1072m, 1059m, 1025w, 937w,
1
875sh, 828vs, 737vs, 692s, 671s. H NMR (CDCl3, 300 MHz) δ:
1.79 (6H, s, 2 CH3 ortho-Mes), 2.30 (3H, s, CH3 para-Mes), 3.32
(2H, t, 3J = 6.0 Hz, NCH2CH2S), 4.43 (2H, t, 3J = 6.0 Hz, NCH2-
CH2S), 6.80 and 7.36 (2H, AB spin system, 3J = 1.6 Hz, CHdCH-
NCH2 and MesNCHdCH), 6.84 (2H, s, 2H meta-Mes), 7.24-7.26
(5H, m, H aromatics). 13C{1H} NMR (CDCl3, 75.5 MHz) δ: 17.87
(2 CH3 ortho-Mes), 21.21 (CH3 para-Mes), 35.62 (NCH2CH2S),
50.94 (NCH2CH2S), 122.19, 122.53 (CHdCH), 126.60 (CH para-
Ph), 129.16 (2 CH meta-Ph), 129.32 (2 CH meta-Mes), 129.42 (2
CH ortho-Ph), 134.91 (C ipso-Mes), 134.98 (2 C ortho-Mes), 135.64
(C ipso-Ph), 139.01 (C para-Mes), 183.10 (NCN). MS (ESI): m/z
431.1 [M - I]þ.
Route B: Zwitterion 14 (0.100 g, 0.23 mmol) and Cs2CO3
(0.076 g, 0.23 mmol). Yield: 74%.
Synthesis of 11: R = methyl; R0 = phenyl.
Route A: 3 HCl (0.250 g, 0.98 mmol), Ag2O (0.227 g, 0.98
3
mmol), and [PdCl2(cod)] (0.280 g, 0.98 mmol). The product was
isolated as a yellow solid. Yield: 77%. Anal. Calcd for
C12H14Cl2N2PdS (395.64): C, 36.43; H, 3.57; N, 7.08. Found:
C, 35.78; H, 3.22; N, 7.42. FTIR: νmax(solid)/cm-1: 3162w,
3124w, 3055w, 2946br, 1582w, 1572w, 1479w, 1466m, 1438s,
1405m, 1356w, 1337w, 1279w, 1230s, 1185sh, 1161w, 1120sh,
1087m, 1023m, 977w, 893w, 835w, 765sh, 742s, 727vs, 700s,
686vs, 672s, 311vs (νPd-Cl), 296vs (νPd-Cl). 1H NMR (CD2Cl2,
300 MHz) δ: 3.06 (2H, br, NCH2CH2S), 3.91 (3H, br s, CH3),
4.63 (2H, br, NCH2CH2S), 6.88 (1H, br s, CHdCH), 7.04 (1H,
br s, CHdCH), 7.37-7.45 (5H, m, H phenyl). MS (ESI): m/z
361.0 [M - Cl]þ.
8 AgI: R = 2,6-diisopropylphenyl; R0 = phenyl. The same
3
procedure was used with 8 HI (0.100 g, 0.20 mmol) and Ag2O
3
(0.047 g, 0.20 mmol). The product was isolated as a light-
sensitive white solid. Yield: 68%. Anal. Calcd for C23H28-
AgIN2S (599.32): C, 46.09; H, 4.71; N, 4.67. Found: C, 45.62;
H, 4.33; N, 5.04. FTIR: νmax(solid)/cm-1: 3143br, 2962s, 2927m,
2869m, 1591w, 1563w, 1549w, 1458s, 1414s, 1363m, 1261m,
1218w, 1182w, 1105m, 1072m, 1059s, 960w, 938w, 876m, 833vs,
1
761w, 737m, 687w. H NMR (CDCl3, 300 MHz) δ: 0.86 and
Route B: Zwitterion 15 (0.100 g, 0.23 mmol) and Cs2CO3
(0.75 g, 0.23 mmol). Yield: 71%.
3
1.07 (2 ꢀ 6H, 2 d, J = 6.9 Hz, 2 CH(CH3)2), 2.33 (2H, sept,
3J = 6.9 Hz, 2 CH(CH3)2), 3.04 (2H, br, NCH2CH2S), 4.28 (2H,
br, NCH2CH2S), 7.02 and 7.54 (2H, AB spin system, 3J = 1.8
Hz, CHdCHNCH2 and DiipNCHdCH), 7.13 (2H, d, 3J = 7.5
Hz, 2H meta-Diip), 7.21-7.28 (5H, m, H aromatics), 7.43 (1H, t,
3J = 7.5 Hz, H para-Diip). MS (ESI): m/z 473.1 [M - I]þ.
Synthesis of the Mono-NHC Chelated Palladium Dichloride
Complexes 10-12. The low solubility of these compounds in
organic solvents prevented recording of their 13C{1H} NMR
spectra. Two synthetic methods, routes A and B, are detailed
below.
Synthesis of 12: R = n-butyl; R0 = phenyl.
Route A: 4 HCl (0.250 g, 0.84 mmol), Ag2O (0.195 g, 0.84
3
mmol), and [PdCl2(cod)] (0.240 g, 0.84 mmol). The product was
isolated as a yellow solid. Yield: 84%. Anal. Calcd for C15H20Cl2-
N2PdS (437.72): C, 41.16; H, 4.61; N, 6.40. Found: C, 41.48; H,
4.39; N, 6.09. FTIR: νmax(solid)/cm-1: 3158w, 3128w, 3099w,
3058w, 2956m, 2929m, 2870w, 1734w, 1719w, 1580w, 1563w,
1472m, 1457m, 1441s, 1425s, 1414m, 1377w, 1356w, 1336w, 1283w,
1240m, 1218w, 1197w, 1159w, 1134w, 1109w, 1059w, 1024w, 999w,
955w, 870w, 739vs, 708w, 686vs, 295vs (νPd-Cl).1HNMR(CD2Cl2,
300 MHz) δ:0.88(3H,t,3J=7.3Hz,CH3),1.29(2H,m,CH2CH3),
1.65 (2H, br m, CH2CH2CH3), 3.17 (2H, br, NCH2CH2S), 4.44
(2H, br, NCH2CH2CH2), 4.65 (2H, br, NCH2CH2S), 7.00 (1H,
Route A: The Transmetalation Reaction. The imidazolium
chloride was dissolved in dry CH2Cl2, and solid Ag2O was
added under nitrogen. The reaction mixture was stirred for 2 h

Article
Organometallics, Vol. 29, No. 21, 2010 5625
br s, CHdCH), 7.18 (H, br s, CHdCH), 7.37-7.45 (5H, m, H
phenyl). MS (ESI): m/z 403.0 [M - Cl]þ.
1041sh, 1022w, 1001w, 967w, 949w, 917w, 895sh, 882w, 855m,
826sh, 806sh, 743vs, 688s, 332vs (νPd-Cl), 305vs (νPd-Cl), 287vs
(νPd-Cl). 1H NMR (d6-DMSO, 300 MHz) δ: 0.90 (3H, t, 3J = 7.5
Hz, CH3 butyl), 1.25 (2H, m, CH2CH3), 1.73 (2H, m, CH2CH2-
CH3), 3.50 (2H, t, 3J = 6.3 Hz, NCH2CH2S), 4.13 (2H, t, 3J = 7.2
Hz, NCH2CH2CH2), 4.38 (2H, t, 3J = 6.3 Hz, NCH2CH2S),
Route B: Zwitterion 16 (0.120 g, 0.25 mmol) and Cs2CO3
(0.082 g, 0.25 mmol). Yield: 69%.
Synthesis of the Zwitterionic Palladium Complexes 13-16.
Because of their low solubility in organic solvents, recording of
the 13C{1H} NMR spectra of complexes 13-15 was prevented.
13: R = methyl; R0 = ethyl. Solid [PdCl2(cod)] (0.276 g, 0.97
3
7.22-7.39 (5H, m, H phenyl), 7.74 (1H, pseudo t, J=4J=1.5
Hz, CHdCH), 7.79 (1H, pseudo t, 3J=4J=1.5 Hz, CHdCH), 9.18
(1H, br s, NCHN). 13C{1H} NMR (d6-DMSO, 75.5 MHz) δ: 13.75
(CH3), 19.20 (NCH2CH2CH2CH3), 31.75 (NCH2CH2S), 32.69
(NCH2CH2CH2CH3), 48.33 (NCH2CH2CH2CH3), 49.02 (NCH2-
CH2S), 122.84, 123.11 (CHdCH), 126.99 (C para-phenyl), 129.32
(C meta-phenyl), 129.70 (C ortho-phenyl), 136.86 (C ipso-phenyl),
NCN resonance not observed. MS (ESI): m/z 498.0 [M þ Na]þ,
440.0 [M - Cl]þ.
Synthesis of the Bis-NHC Palladium Dichloride Complexes
18-20. The transmetalation reaction procedure described
above (route A) was followed for these complexes.
18: R = n-butyl; R0 = ethyl.
mmol) was added to a solution of 1 HCl (0.200 g, 0.97 mmol) in
3
dichloromethane. The reaction mixture was stirred for 2 h at
room temperature, until a yellow precipitate appeared. The
solvent was removed via canula, and the solid was washed with
pentane (2 ꢀ 20 mL) and dried under vacuum. The product was
isolated as a yellow solid. Yield: 87%. Anal. Calcd for C8H15-
Cl3N2PdS (384.06): C, 25.02; H, 3.94; N, 7.29. Found: C, 25.30;
H, 3.64; N, 7.44. FTIR: νmax(solid)/cm-1: 3160w, 3090s, 3071s,
3007w, 2958w, 2924sh, 2942w, 2866w, 1639w, 1574m, 1558s,
1450s, 1427s, 1375m, 1330w, 1314w, 1285w, 1272w, 1250w,
1225m, 1165vs, 1122m, 1090sh, 1061m, 1046w, 1016m, 991w,
970w, 856vs, 798m, 767vs, 752s, 711w, 347vs (νPd-Cl), 306vs
(νPd-Cl), 286vs (νPd-Cl). 1H NMR (d6-DMSO, 300 MHz) δ: 1.19
(3H, t, 3J = 7.5 Hz, SCH2CH3), 2.57 (overlapped with solvent
peak, SCH2CH3), 2.99 (2H, t, 3J = 6.6 Hz, NCH2CH2S), 3.89
(3H, s, NCH3), 4.37 (2H, t, 3J = 6.6 Hz, NCH2CH2S), 7.73 (1H,
br s, CHdCH), 7.82 (1H, br s, CHdCH), 9.22 (1H, br s,
NCHN). MS (ESI): m/z 407.9 [M þ Na]þ, 348.9 [M - Cl]þ.
14: R = n-butyl; R0 = ethyl.
2 HCl (0.200 g, 0.80 mmol), Ag2O (0.186 g, 0.80 mmol), and
3
[PdCl2(cod)] (0.115 g, 0.40 mmol). The product was isolated as a
yellow solid. Yield: 74%. Anal. Calcd for C22H40Cl2N4PdS2
(602.03): C, 43.89; H, 6.70; N, 9.31. Found: C, 43.48; H, 6.44; N,
9.62. FTIR: νmax(solid)/cm-1: 3163br, 3126br, 3048br, 2959br,
2940br, 2872br, 2360w, 2162w, 2050w, 1582w, 1479m, 1461m,
1439m, 1421s, 1381m, 1355m, 1276m, 1232m, 1203w, 1159w,
1130w, 1107w, 1088w, 1024m, 935w, 896w, 871w, 833w, 800w,
759m, 736vs, 728vs, 705vs, 689vs, 669m, 340vs (νPd-Cl). 1H
The same procedure was used with [PdCl2(cod)] (0.229 g, 0.80
mmol) and 2 HCl (0.200 g, 0.80 mmol). The product was
3
NMR (CD2Cl2, 300 MHz) δ: 1.05 (3H, t, J = 7.5 Hz, CH3
3
butyl), 1.23 (3H, t, 3J = 7.5 Hz, SCH2CH3), 1.51 (2H, m, NCH2-
CH2CH2CH3), 2.01 (2H, m, NCH2CH2CH2CH3), 2.69 (2H, q,
3J = 7.5 Hz, SCH2CH3), 3.53 (2H, br, NCH2CH2S), 4.51 (2H, q,
3J = 7.2 Hz, NCH2CH2CH2CH3), 4.66 (2H, br, NCH2CH2S),
isolated as a yellow solid. Yield: 89%. Anal. Calcd for
C11H21Cl3N2PdS (426.14): C, 31.00; H, 4.97; N, 6.57. Found:
C, 30.31; H, 5.17; N, 6.09. FTIR: νmax(solid)/cm-1: 3136br,
3103s, 3078m, 2964m, 2930m, 2875br, 2861br, 1620w, 1564vs,
1451s, 1414s; 1405m, 1371m, 1355m, 1338w, 1308m, 1299w,
1268m, 1245w, 1226w, 1205w, 1178vs, 1157vs, 1122w, 1111w,
1069w, 1041w, 1005w, 956w, 891w, 838vs, 825s, 780m, 756vs,
3
6.91 and 7.09 (2H, AB spin system, J = 1.8 Hz, CHdCH).
13C{1H} NMR (CD2Cl2, 300 MHz) δ: 13.73 (CH3 butyl), 14.75
(SCH2CH3), 20.04 (NCH2CH2CH2CH3), 26.18 (SCH2CH3),
31.08 (NCH2CH2S), 32.07 (NCH2CH2CH2CH3), 50.72 (NCH2-
CH2CH2CH3), 51.00 (NCH2CH2S), 118.93, 121.51 (CHdCH),
NCN resonance not observed. MS (ESI): m/z 568.2 [M - Cl]þ.
19: R = methyl; R0 = phenyl.
1
749s, 344vs (νPd-Cl), 312vs (νPd-Cl), 286vs (νPd-Cl). H NMR
(d6-DMSO, 300 MHz) δ: 0.90 (3H, t, 3J = 7.5 Hz, CH3 butyl),
1.17 (3H, t, 3J = 7.5 Hz, SCH2CH3), 1.26 (2H, m, NCH2CH2-
CH2CH3), 1.78 (2H, m, NCH2CH2CH2CH3), 2.54 (overlapped
with solvent peak, SCH2CH3), 2.90 (2H, t, 3J = 6.0 Hz,
3 HCl (0.200 g, 0.79 mmol), Ag2O (0.182 g, 0.79 mmol), and
3
3
NCH2CH2S), 4.20 (2H, t, J = 7.2 Hz, NCH2CH2CH2CH3),
[PdCl2(cod)] (0.112 g, 0.39 mmol). The product was isolated as a
yellow solid. Yield: 72%. Anal. Calcd for C24H28Cl2N4PdS2
(613.96): C, 46.95; H, 4.60; N, 9.13. Found: C, 50.24; H, 4.58;
N, 9.41. FTIR: νmax(solid)/cm-1: 3161br, 3124br, 3098br,
3055br, 2947br, 1582w, 1572w, 1535w, 1479w, 1467m, 1439m,
1406m, 1356w, 1338w, 1279w, 1260w, 1230m, 1162w, 1087s,
1022s, 953w, 893w, 875w, 834w, 798m, 742s, 727vs, 698s, 687vs,
657w, 337vs (νPd-Cl). 1H NMR (CD2Cl2, 300 MHz) δ: 3.72 (2H,
4.36 (2H, t, 3J = 6.3 Hz, NCH2CH2S), 7.81 (2H, br s, CHdCH),
9.23 (1H, br s, NCHN). MS (ESI): m/z 450.0 [M þ Na]þ, 392.0
[M - Cl]þ.
15: R = methyl; R0 = phenyl.
The same procedure was used with [PdCl2(cod)] (0.224 g, 0.79
mmol) and 3 HCl (0.200 g, 0.79 mmol). The product was
3
isolated as a yellow solid. Yield: 84%. Anal. Calcd for
C12H15Cl3N2PdS (432.10): C, 33.35; H, 3.50; N, 6.48. Found:
C, 32.94; H, 3.39; N, 7.01. FTIR: νmax(solid)/cm-1: 3155br,
3123w, 3111m, 3075m, 2982m, 2935w, 1618w, 1572m, 1479w,
1450w, 1443m, 1432m, 1423sh, 1404w, 1352m, 1313m, 1299m,
1275w, 1248w, 1176vs, 1170vs, 1110m, 1072w, 1047w, 1020w,
1000w, 954w, 924w, 890w, 838s, 753vs, 690vs, 668w, 335vs
3
t, J = 6.9 Hz, NCH2CH2S), 4.08 (3H, s, NCH3), 4.65 (2H, t,
3J = 6.9 Hz, NCH2CH2S), 6.82 and 6.88 (2H, AB spin system,
3J = 1.8 Hz, CHdCH), 7.18-7.46 (5H, m, H phenyl). MS (ESI):
m/z 580.1 [M - Cl]þ.
20: R = n-butyl; R0 = phenyl.
4 HCl (0.200 g, 0.67 mmol), Ag2O (0.156 g, 0.67 mmol), and
3
1
(νPd-Cl), 306vs (νPd-Cl), 287vs (νPd-Cl). H NMR (d6-DMSO,
[PdCl2(cod)] (0.096 g, 0.34 mmol). The product was isolated as a
yellow solid. Yield: 76%. Anal. Calcd for C30H40Cl2N4PdS2
(698.12): C, 51.61; H, 5.78; N, 8.03. Found: C, 52.02; H, 5.39; N,
7.66. FTIR: νmax(solid)/cm-1: 3158br, 3123br, 3096br, 3055br,
2957s, 2929s, 2871m, 1582m, 1480m, 1464m, 1439m, 1423m,
1378w, 1356w, 1278w, 1232m, 1202w, 1158w, 1132w, 1088w,
1041w, 1024w, 736vs, 703s, 691vs, 668w, 347vs (νPd-Cl). 1H
300 MHz) δ: 3.49 (2H, t, 3J = 6.6 Hz, NCH2CH2S), 3.81 (3H, s,
NCH3), 4.38 (2H, t, 3J = 6.6 Hz, NCH2CH2S), 7.23-7.40 (5H,
m, H phenyl), 7.62 (1H, br s, CHdCH), 7.74 (1H, br s,
CHdCH), 9.10 (1H, br s, NCHN). MS (ESI): m/z 455.9 [M þ
Na]þ, 397.9 [M - Cl]þ.
16: R = n-butyl; R0 = phenyl.
3
The same procedure was used with [PdCl2(cod)] (0.192 g, 0.67
mmol) and 4 HCl (0.200 g, 0.67 mmol). The product was isolated
NMR (CD2Cl2, 300 MHz) δ: 0.99 (3H, t, J = 7.2 Hz, CH3
butyl), 1.45 (2H, m, NCH2CH2CH2CH3), 2.05 (2H, m, NCH2-
CH2CH2CH3), 3.72 (2H, q, 3J = 6.9 Hz, NCH2CH2S), 4.46 (2H,
q, 3J = 7.5 Hz, NCH2CH2CH2CH3), 4.68 (2H, q, 3J = 6.9 Hz,
NCH2CH2S), 6.82 and 6.88 (2H, AB spin system, 3J = 1.8 Hz,
CHdCH), 7.16-7.42 (5H, m, H phenyl). 13C{1H} NMR
(CD2Cl2, 75 MHz) δ: 13.60 (CH3), 20.07 (NCH2CH2CH2-
CH3), 33.04 (NCH2CH2S), 34.33 (NCH2CH2CH2CH3), 49.91
3
as a yellow solid. Yield: 81%. Anal. Calcd for C15H21Cl3N2PdS
(474.18): C, 37.99; H, 4.46; N, 5.91. Found: C, 37.48; H, 4.23; N,
5.70. FTIR: νmax(solid)/cm-1: 3130w, 3100m, 3056m, 2984sh,
2954sh, 2934w, 2859br, 1619w, 1577w, 1562s, 1468w, 1453m,
1440s, 1411w, 1382w, 1367w, 1346w, 1333w, 1311w, 1300w,
1249w, 1215w, 1207w, 1169s, 1151s, 1113w, 1101w, 1071w,

5626 Organometallics, Vol. 29, No. 21, 2010
Fliedel and Braunstein
(NCH2CH2CH2CH3), 50.58 (NCH2CH2S), 120.37, 121.41
(CHdCH), 126.24 (C para-phenyl), 129.09 (C meta-phenyl),
129.23 (C ortho-phenyl), 135.13 (C ipso-phenyl), 170.10 (NCN).
MS (ESI): m/z 664.2 [M - Cl]þ.
Synthesis of the Bis-NHC Dicationic Palladium Complexes
21-24. The transmetalation reaction procedure described
above (route A) was followed for these complexes.
21: R = methyl; R0 = ethyl.
δ: 15.08 (CH3), 21.26 (NCH2CH2CH2CH3), 33.67 (NCH2CH2S),
34.95 (NCH2CH2CH2CH3), 51.82 (NCH2CH2CH2CH3), 52.76
(NCH2CH2S), 124.27, 125.38 (CHdCH), 130.96 (C para-phenyl),
131.70 (C meta-phenyl), 132.18 (C ortho-phenyl), 132.41 (C ipso-
phenyl), NCN resonance not observed.
General Procedure for the Suzuki-Miyaura Cross-Coupling
Reaction. The catalyst precursor (0.02 mmol), phenyl boronic
acid (146.3 mg, 1.20 mmol), and Cs2CO3 (651.6 mg, 2.00 mmol)
were placed in a Schlenk tube, and DMSO (3 mL) was added under
nitrogen. Then 4-bromotoluene (123.1 μL, 171.0 mg, 1.00 mmol)
was added, and the reaction mixture was heated for 2 h at 60 °C.
The reaction was then quenched by rapid cooling to room tem-
perature, and the suspension was filtered through a Celite pad. The
resulting solution was then analyzed by gas chromatography. All
runs were repeated two times, and the value reported is an average
of the two yields measured. The corresponding yields in 4-methyl-
biphenyl are reported in Tables 1 and 3.
The same procedure was used with different solvents (3 mL)
or different bases (2.00 mmol), and the corresponding yields in
4-methyl-biphenyl are reported in Table 2.
The same procedure was used with catalyst (0.01 mmol) or
4-chlorotoluene (118.3 μL, 126.6 mg, 1.00 mmol) as reagent
instead of 4-bromotoluene, and the corresponding yields in
4-methyl-biphenyl are reported in Table 4.
1 HCl (0.200 g, 0.97 mmol), Ag2O (0.224 g, 0.97 mmol), and
3
[Pd(NCMe)4][BF4]2 (0.215 g, 0.48 mmol). The product was
isolated as a light brown solid. Yield: 68%. Anal. Calcd for C16H28-
B2F8N4PdS2 (620.58): C, 30.97; H, 4.55; N, 9.03. Found: C, 30.39;
H, 5.04; N, 8.76. FTIR: νmax(solid)/cm-1: 3166br, 3140br, 2966br,
2933br, 1628br, 1568w, 1543w, 1527w, 1474m, 1453m, 1411m,
1381w, 1363w, 1337w, 1286w, 1268w, 1244w, 1214w, 1172w,
1
1030vs, 877w, 848w, 752s, 688m, 679m, 659w. H NMR (CD3-
CN, 300 MHz) δ:1.23(3H, t, 3J=6.9Hz, SCH2CH3),2.67(2H, br,
SCH2CH3), 2.96 (2H, br, NCH2CH2S), 3.86 (3H, s, NCH3), 4.45
(2H, br, NCH2CH2S), 7.18 (1H, br s, CHdCH), 7.32 (1H, br s,
CHdCH). 13C{1H} NMR (CD3CN, 75 MHz) δ: 13.38 (SCH2-
CH3),32.36(SCH2CH3), 32.25 (NCH2CH2S), 38.20 (NCH3),50.59
(NCH2CH2S), 124.33, 125.86 (CHdCH), 157.82 (NCN).
22: R = n-butyl; R0 = ethyl.
2 HCl (0.200 g, 0.80 mmol), Ag2O (0.186 g, 0.80 mmol), and
3
[Pd(NCMe)4][BF4]2 (0.179 g, 0.40 mmol). The product was
isolated as a light brown solid. Yield: 67%. Anal. Calcd for
C22H40B2F8N4PdS2 (704.74): C, 37.49; H, 5.72; N, 7.95. Found:
C, 37.01; H, 5.30; N, 8.34. FTIR: νmax(solid)/cm-1: 3144br,
3112sh, 2961m, 2933m, 2874w, 1623br, 1565w, 1533w, 1457m,
1427m, 1379w, 1354w, 1241w, 1201w, 1162m, 1047vs, 1033vs,
X-ray Data Collection, Structure Solution, and Refinement for
All Compounds. Suitable crystals for the X-ray analysis of all
compounds were obtained as described above. The intensity data
were collected on a Kappa CCD diffractometer32 (graphite-mono-
˚
chromatedMoKRradiation, λ= 0.71073 A) at 173(2) K. Crystallo-
graphic and experimental details for the structures are summarized
in Table 1. The structures were solved by direct methods (SHELXS-
97) and refined by full-matrix least-squares procedures (based on
F2, SHELXL-97)33 with anisotropic thermal parameters for all the
non-hydrogen atoms. The hydrogen atoms were introduced into
the geometrically calculated positions (SHELXS-97 procedures)
and refined riding on the corresponding parent atoms, except for the
H1 atom in the structure of 8 HPF6. For 8 HPF6, the PF6 anion
1
875w, 849w, 750s, 691m. H NMR (CD2Cl2, 300 MHz) δ: 0.85
(3H, t, 3J = 7.5 Hz, CH3 butyl), 1.20 (3 h, t, 3J = 7.5 Hz, SCH2-
CH3), 1.35 (2H, m, NCH2CH2CH2CH3), 1.84 (2H, m, NCH2CH2-
CH2CH3), 2.53 (2H, br q, SCH2CH3), 2.95(2H, brt, NCH2CH2S),
4.17 (2H, br t, NCH2CH2CH2CH3), 4.37 (2H, br t, NCH2CH2S),
7.15 (2H, br s, CHdCH). 13C{1H} NMR (CD2Cl2, 75 MHz) δ:
13.30 (CH3 butyl), 14.19 (SCH2CH3), 19.79 (NCH2CH2CH2-
CH3), 25.62 (SCH2CH3), 31.35 (NCH2CH2S), 32.44 (NCH2CH2-
CH2CH3), 49.83 (NCH2CH2CH2CH3), 50.90 (NCH2CH2S),
122.64, 122.72 (CHdCH), 157.06 (NCN).
3
3
was found disordered in two positions with equal occupancy factors
and with a F-P-F axis in common. The disorder could be refined
unrestrained. For [5 (AgI)2]2, the mesityl group was disordered
3
23: R = methyl; R0 = phenyl.
with very close images. It was not possible to define the atomic
coordinates for the two images of this disorder. Instead, this group
was refined with restrained anisotropic parameters. A MULTI-
SCAN correction was applied.34 CCDC 778208-778212 contain
the supplementary crystallographic data for this paper, which can
be obtained free of charge from the Cambridge Crystallographic
Data Center via www.ccdc.cam.ac.uk/data_request/cif.
3 HCl (0.200 g, 0.79 mmol), Ag2O (0.182 g, 0.79 mmol), and
3
[Pd(NCMe)4][BF4]2 (0.174 g, 0.39 mmol). The product was
isolated as a light brown solid. Yield: 64%. Anal. Calcd for
C24H28B2F8N4PdS2 (716.66): C, 40.22; H, 3.94; N, 7.82. Found:
C, 40.68; H, 3.69; N, 8.16. FTIR: νmax(solid)/cm-1: 3168w,
3141w, 2956w, 2922w, 2851w, 1577w 1544w, 1473m, 1442m,
1408m, 1359w, 1337w, 1284w, 1241w, 1206w, 1171w, 1031vs,
999vs, 887m, 847w, 742s, 686s. 1H NMR (CD2Cl2, 300 MHz) δ:
3.37 (2H, br t, NCH2CH2S), 4.33 (2H, br, NCH2CH2S), 4.84
(3H, br s, CH3), 7.02-7.42 (7H, m, CHdCH and H phenyl).
13C{1H} NMR (CD2Cl2, 75 MHz) δ: 33.75 (NCH2CH2S), 37.54
(NCH3), 51.38 (NCH2CH2S), 123.42, 123.54 (CHdCH), 127.21
(C para-phenyl), 129.38 (C meta-phenyl), 130.18 (C ortho-
phenyl), 132.90 (C ipso-phenyl), 155.20 (NCN).
Acknowledgment. We thank Gilles Schnee (University
of Strasbourg) and Alessandra Sabbatini (University of
Camerino, Italy) for their contribution to this work and
ꢀ
Marc Mermillon-Fournier and Melanie Boucher for
technical assistance. We are most grateful to Dr. Roberto
Pattacini for the resolution of the X-ray structures and to
24: R = n-butyl; R0 = phenyl.
ꢁ
the CNRS, the Ministere de la Recherche (Paris), and the
DFH/UFA (International Research Training Group
532-GRK532) for funding.
4 HCl (0.200 g, 0.67 mmol), Ag2O (0.156 g, 0.67 mmol), and
3
[Pd(NCMe)4][BF4]2 (0.150 g, 0.34 mmol). The product was
isolated as a light brown solid. Yield: 71%. Anal. Calcd for
C30H40B2F8N4PdS2 (800.82): C, 44.99; H, 5.03; N, 7.00. Found: C,
45.39; H, 5.14; N, 6.67. FTIR: νmax(solid)/cm-1: 3149br, 3112sh,
2960w, 2932w, 2873w, 2113w, 1724w, 1564w, 1473m, 1458sh,
1442m, 1430w, 1381w, 1356w, 1338w, 1285w, 1242w, 1163w,
1049vs, 1034vs, 1000s, 846w, 745s, 688m. 1H NMR (CD2Cl2, 300
MHz) δ: 0.91 (3H, t, 3J = 7.3 Hz, CH3), 1.30 (2H, m, CH2CH3),
1.78 (2H, br m, CH2CH2CH3), 3.66 (2H, br, NCH2CH2S), 4.45
(2H, br, NCH2CH2CH2), 4.78 (2H, br, NCH2CH2S), 7.23-7.45
(7H, m, CHdCH and H phenyl). 13C{1H} NMR (CD2Cl2,75MHz)
Supporting Information Available: Table S-1 with the crystal-
lographic data and CIF files for all the structures. This material
is available free of charge via the Internet at http://pubs.acs.org.
(32) Bruker-Nonius. Kappa CCD Reference Manual; Nonius BV: The
Netherlands, 1998.
(33) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112–122.
(34) Spek, L. J. Appl. Crystallogr. 2003, 36, 7. Blessing, B. Acta
Crystallogr. 1995, A51, 33.