Preparation of NHC-substituted phosphitepalladacycles

Article abstract of DOI:10.1016/j.jorganchem.2007.03.020

The preparation of unsaturated NHC-substituted phosphitepalladacycles via phosphitepalladacycle acetato and chloro precursors and azolium salts with non-coordinating anions in DMSO is reported. With this one-pot synthesis NHC-substituted phosphitepalladac

Full text of DOI:10.1016/j.jorganchem.2007.03.020

Journal of Organometallic Chemistry 692 (2007) 3316–3327
www.elsevier.com/locate/jorganchem
q
Preparation of NHC-substituted phosphitepalladacycles
a
a
a
Alexandrina D. Tanase , Guido D. Frey , Eberhardt Herdtweck ,
b
a,
*
Stephan D. Hoffmann , Wolfgang A. Herrmann
a
Department Chemie, Lehrstuhl fu¨r Anorganische Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstraße 4, D-85747 Garching, Germany
Department Chemie, Lehrstuhl fu¨r Anorganische Chemie mit Schwerpunkt Neue Materialien, Technische Universita¨t Mu¨nchen, Lichtenbergstraße 4,
D-85747 Garching, Germany
b
Received 4 February 2007; received in revised form 1 March 2007; accepted 6 March 2007
Available online 23 March 2007
¨
Dedicated to Dr. Karl Ofele on the occasion of his 75th birthday.
Abstract
The preparation of unsaturated NHC-substituted phosphitepalladacycles via phosphitepalladacycle acetato and chloro precursors
and azolium salts with non-coordinating anions in DMSO is reported. With this one-pot synthesis NHC-substituted phosphitepallada-
cycles are obtained avoiding multi-step reactions. The molecular structures of an acetate-bridged phosphitepalladacycle dimer, an unsat-
urated NHC-substituted palladacyclic complex and one acetylacetonato phosphapalladacycle complex have been determined by single-
crystal X-ray analysis.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Carbenes; Palladacycle; Palladium; Phosphite; NHCs; In situ method
1. Introduction
beneficial in their use as ligands in organometallic catalysis
[13]. Most of the palladium complexes can be used as cata-
lysts for various carbon–carbon bond formations and
related reactions [14]. Hartwig and co-workers demon-
strated that catalysts containing saturated NHCs could be
used in the room-temperature ‘‘Buchwald–Hartwig’’ ami-
nation of non-activated aryl chlorides [15], while Caddick
and Kofie demonstrated the efficiency of palladium cata-
lysts based on these saturated NHCs (formed in situ by
deprotonation of the imidazolium salt) in intramolecular
Mizoroki–Heck couplings of aryl chloride substrates [16].
The combination of a palladacycle framework with an
NHC was reported first in 1997 by our group [17–19],
and became an important class of novel NHC-substituted
palladium complexes for catalysis. These catalysts, with
unsaturated NHC ligands, have proved to be effective in
the coupling of aryl chloride substrates with arylalkenes
[19,20]. NHC substituted phosphapalladacycles combine
the advantageous stability of phosphapalladacycles with
the steric bulk and high r-donor strength of N-heterocyclic
carbenes [19].
Palladacycles have been known for over 30 years [1–4]
and have been used recently as catalysts [5,6]. Many groups
also use ortho-metallated complexes as Pd(II)-precatalysts
in which an aromatic carbon atom adjacent to a functional
group is bound to the metal center. Milstein produced effi-
cient catalysis with aryl-metallated ‘‘pincer’’ complexes [7],
and also acetylacetonate-substituted phosphapalladacycles
were used as catalyst systems for the Mizoroki–Heck reac-
tion [8,9].
Another class of potential catalysts was introduced in
1993; those featuring N-heterocyclic carbene (NHC) ligands
[10]. N-Heterocyclic carbenes have the advantageous prop-
erty of forming strong r-bonds to metal centers, with little
tendency towards dissociation [11,12]. This is particularly
q
N-Heterocyclic carbenes, Part 50. For part 49, see Ref. [31].
Corresponding author. Tel.: +49 89 289 13080; fax: +49 89 289 13473.
*
E-mail addresses: guido.frey@ch.tum.de (G.D. Frey), lit@arthur.
anorg.chemie.tu-muenchen.de (W.A. Herrmann).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.03.020

A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
3317
Bedford and co-workers published in 1998 an ortho-met-
allated triaryl phosphite chloro palladium complex, which
was found to be a highly active catalyst in biaryl coupling
reactions [21]. The analogous acetate complex was synthe-
sized in 2004 [22]. A monograph about N-heterocyclic car-
bene adducts of both chloro- and acetato-ortho-palladated
phosphite complexes was published at the beginning of
2005 [20]; almost simultaneously Bedford et al. reported a
small variety of saturated N-heterocyclic carbene adducts
of ortho-palladated triarylphosphite complexes and their
catalytic activities in the Suzuki–Miyaura coupling [23].
Because of the high stability of these acetato and chloro
NHC-phosphitepalladacycles, we extended our previous
work [20] by varying the carbenes and the palladacycles
to investigate their chemical properties.
Fig. 1. ORTEP style plot [30h] of compound 1a in the solid state. Thermal
ellipsoids are drawn at the 50% probability level. Hydrogen atoms are
omitted for clarity.
2. Results and discussion
2.1. ortho-Metallated dimeric complex
Most of the crystal structures of ortho-palladated tri-
aryl-phosphite dimers indicate that in the solid state, the
trans isomer crystallizes preferentially, where the two phos-
phorus atoms are coordinated trans to each other at the
palladium center, although in our case the solid state struc-
ture of 1a depicts the cis isomer, in contrast to previously
reported ortho-palladated triarylphosphane dimer [19,24].
The two Pd atoms in 1a adopt square planar geometry
and are connected by two bridging acetate ligands. The
angles around the palladium center deviate from 90ꢁ due
to the bite angle of the cyclometalated ligand [P1–Pd1–
C7 79.21(6)ꢁ; P2–Pd2–C57 80.86(6)ꢁ]. No significant differ-
ences of the bond lengths between the coordinated atoms
and the palladium center were observed compared to other
published palladaphosphites [21,23].
The acetate-bridged phosphitepalladacycle dimer 1a is
prepared in a similar way to these of Bedford and co-work-
ers for the analogous chloride complex 1b [21]. When
Pd(OAc)2 (a) or PdCl2 (b) is treated with the sterically
demanding tris-(2,4-di-tert-butylphenyl)phosphite (1) in
monomethylglycol ether at 80 ꢁC, the colorless complexes
1a and 1b are formed in high yields (93–96%) (Scheme 1)
[20,21].
Complex 1a could be identified as a mixture of cis- and
trans-isomers in solution, with two signals in the 31P NMR
spectrum (126.7 and 124.8 ppm; intensity = 1:1), in agree-
ment with the published values of complex 1b (119.2 and
118.7 ppm) [20,21]. The remarkable air, moisture, and ther-
mal stability of complex 1a is comparable to the analogous
chloride complex 1b. Complex 1a has been characterized
by spectroscopic methods and elemental analysis. Suitable
single crystals of complex 1a for X-ray diffraction were
obtained by slow evaporation of a saturated dichlorometh-
ane solution. The solid state structure of the complex 1a is
shown in Fig. 1 and selected bond lengths and angles are
given in Table 2.
2.2. NHC-substituted phosphitepalladacycles
Nowadays it is possible to synthesize NHC-palladacycle
complexes in two different ways. Firstly we used the ‘‘free
carbene’’ route [19] for highly sterically hindered carbene
ligands (Scheme 2), or without isolation of the free carbene
the ‘‘in situ’’ method, when palladium acetate is used as the
starting material [24] (Scheme 3).
Reaction of the bulky ortho-palladated triarylphosphite
complexes 1a and 1b with the free carbene ligands (2–7), in
THF at room temperature, give the mono- and disubsti-
tuted complexes 2a–7b.
X
If the palladacycles 1a and 1b are treated with 2.1 equiv.
of a less sterically hindered carbene such as 1,3-dicyclo-
hexylimidazolin-2-ylidene (6), the acetate and chloride
products with two N-heterocyclic carbene ligands are
formed (6a,b) (Scheme 2). The coordination of two carb-
enes at one metal center is a good illustration that NHC
ligands are much stronger ligands than the acetate ligand.
These complexes were purified by extraction of the
obtained residue with n-hexane and toluene to remove
traces of unreacted free carbene (6). Using bulky groups
Pd
80 °C
O
2
P
2 PdX2 + 2 P
O
glycol ether
-2 HX
O
O
3
1a: X = κ2μ1-O2CCH3
1b: X = Cl
1
a: X = O2CCH3
b: X = Cl
Scheme 1. Preparation of Bedford-type phosphitepalladacycles 1a and 1b.

3318
A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
R1
N
N
Pd
R2
O
P
X
ArO OAr
2a,b; 3b; 4b; 5b; 7a,b
X
1
toluene
3 h, RT
/
+
2
R1
R2
-Bu
Pd
N
N
O
+ X-
P
2
ArO OAr
2: R1
=
t
-Bu; R2
=
t
R1
N
3: R1 = Mes; R2 = Mes
4: R1 = Me; R2 = Mes
1a: X = O2CCH3
1b: X = Cl
N
R2
Ar = 2,4-(t-Bu)2C6H3
5: R1 = Me; R2 = (C6H5)2CH
6: R1 = Cy; R2 = Cy
Pd
R1
O
P
N
ArO OAr
R2
7: R1 = Me; R2 = Me
N
6a,b
Complex R1
R2
X
Yield [%]
2a / 2b
- / 3b
- / 4b
- / 5b
6a / 6b
7a / 7b
t-Bu
t-Bu
Mes
OAc / Cl
50 / 59
- / 72
Mes
Me
Me
Cy
-
-
-
/ Cl
/ Cl
/ Cl
Mes
- / 86
(C6H5)2CH
Cy
- / 63
OAc / Cl
OAc / Cl
49 / 60
79 / 75
Me
Me
Scheme 2. Synthesis of mono- and disubstituted NHC-phosphitepalladacycles via the ‘‘free carbene’’ route.
on the carbene ligand, such as for example the tert-butyl
group, only monocarbene substituted complexes (2a,b,
3b–5b and 7a,b) were obtained, in accordance with previ-
ously published results [19,24]. The monocarbene-substi-
tuted complexes are obtained in most cases as a mixture
of cis and trans isomers. The reaction of 1a,b with the free
carbene 7, did not proceed as we expected when stoichiom-
etry was held at 2:1 and 1:1, but rather gave a mixture of
mono- and dicarbene substituted compounds as deter-
mined by FAB mass spectrometry and 31P NMR spectra.
When the reaction was repeated and the free carbene 7
was added very slow to a highly diluted metal precursor
toluene solution, at very low temperatures (ꢀ90 ꢁC), the
31P NMR spectra showed two signals in the region for
monocarbene cis/trans products 7a,b. Under these condi-
tions the formation of the mono-substituted NHC com-
plexes 7a,b over the expected di-substituted complexes is
favoured. The formation of a mono-substituted NHC com-
plex shows that the coordination of two NHCs to the pal-
ladium center is not always necessary, especially when the
steric demand of the ligand would disfavour such a
conformation.
O
OAc
+ NaOAc
1
-
+ [NHC-H]+BF4
/
2
Pd
Pd
O
O
O
DMSO
- HOAc
- NaBF4
NHC
P
P
2
ArO OAr
ArO OAr
1a
8
9
3a (56% yield)
5a (60% yield)
Ar = 2,4-(t-Bu)2C6H3
+ BF4
-
-
+ BF4
N
N
N
N
8
9
Scheme 3. In situ method for the preparation of the complexes 3a and 5a.

A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
3319
Table 1
two signals for the phosphorus, suggesting a cis/trans prod-
uct mixture. In the case of dicarbene complex 6a the two
coordinated carbene carbon atoms should be inequivalent,
but only one signal was observed for both carbenes. In con-
trast to complex 6a, two carbene signals were obtained in
the 13C NMR spectra of 6b (175.1 and 173.0 ppm). As
expected the 31P NMR spectra shows only one signal,
because no cis/trans isomerization is possible for these
complexes. In the 13C NMR spectra most of the prepared
complexes show JPC > 16 Hz and JPC 5–16 Hz for the
carbene carbon nuclei.
Colorless crystals of complex 7b suitable for X-ray diffrac-
tion were obtained by slow evaporation of a saturated
CH2Cl2/n-pentane solution (Fig. 2). The palladium center
13C NMR carbene carbon nuclei signals of complexes 2–7
13
Complex
C
carbene
(ppm)
2a/2b
3a/3b
–/4b
5a/5b
6a/6b
7a/7b
175.7/177.5
182.1/no carbene signal was observed
–/186.2
185.2/186.1
178.4/175.1 and 173.0
178.3/178.2
1
2
The acetate-bridged phosphapalladacycle 1a in dimethyl
sulfoxide reacts at elevated temperatures with azolium salts
(8, 9) bearing weakly coordinating anions like BFꢀ4 or PF6ꢀ
via deprotonation to form the corresponding carbene com-
plexes (3a and 5a) [17,25,26]. An additional base (NaOAc)
is necessary for the complete deprotonation of the azolium
salts. For this reaction a temperature dependency was
observed; best results were obtained at reaction tempera-
tures between 75 and 90 ꢁC [24]. The yields of the products
3a and 5a are shown in Scheme 3.
reveals
a
slightly distorted square-planar structure
[Cl1(2)–Pd1(2)–C1(51) 88.91(7)ꢁ, 87.31(7)ꢁ; Cl1(2)–
Pd1(2)–C7(57) 94.26(7)ꢁ, 93.89(7)ꢁ; P1(2)–Pd1(2)–C1
(51) 98.64(7)ꢁ, 99.50(7)ꢁ; P1(2)–Pd1(2)–C7(57) 79.11
(7)ꢁ, 79.42(7)ꢁ]. In contrast to the known saturated car-
bene-substituted phosphitepalladacycles [27], the NHC-
ligand in complex 7b is coordinated cis to the phosphorus
donor [23]. The Pd1(2)–C7(57) bond lengths of the ortho-
metallated phosphite ligand is slightly longer (2.052(2),
For the complexes 2a–7b the 13C NMR signals of the
carbene carbon are in the expected range of 176–190 ppm
for imidazolin-2-ylidene complexes (Table 1). The carbene
signals in complexes 5a,b could not be differentiated in the
13C NMR spectra, but the 31P NMR spectra show clearly
˚
2.063(2) A) compared to complex 1a (1.995(2),
˚
˚
2.005(2) A) and 1b (1.998(6) A). In contrast the Pd–P bond
Table 2
Selected bond lengths (A) and bond angles (ꢁ) for 1a Æ (CH2Cl2), 7b Æ 3(CH2Cl2), and 11
˚
Compound
1a Æ (CH2Cl2)
7b Æ 3(CH2Cl2)
11
˚
Bond lengths (A)
Pd1(2)–Cl1(2)
Pd1(2)–P1(2)
Pd1(2)–O4(6)
Pd1(2)–O5(7)
Pd1(2)–C1(51)
Pd1(2)–C7(57)
Pd–P
2.3804(7)/2.3584(7)
2.1590(7)/2.1554(7)
2.1630(6)/2.1535(6)
2.103(2)/2.100(2)
2.127(2)/2.106(2)
2.069(2)/2.077(3)
2.052(2)/2.063(2)
1.995(2)/2.005(2)
2.217(2)
2.111(4)
2.092(4)
2.000(6)
Pd–O1
Pd–O2
Pd–C6
Bond angels (ꢁ)
Cl1(2)–Pd1(2)–P1(2)
Cl1(2)–Pd1(2)–C1(51)
Cl1(2)–Pd1(2)–C7(57)
P1(2)–Pd1(2)–C1(51)
P1(2)–Pd1(2)–C7(57)
C1(51)–Pd1(2)–C7(57)
P1(2)–Pd1(2)–O4(6)
P1(2)–Pd1(2)–O5(7)
O4(6)–Pd1(2)–O5(7)
O4(6)–Pd1(2)–C7(57)
O5(7)–Pd1(2)–C7(57)
P–Pd–O1
169.88(3)/172.89(3)
88.91(7)/87.31(7)
94.26(7)/93.89(7)
98.64(7)/99.50(7)
79.11(7)/79.42(7)
172.17(9)/176.74(9)
79.21(6)/80.86(6)
161.45(4)/172.00(5)
100.36(4)/96.53(5)
88.12(6)/88.47(6)
91.47(7)/93.33(7)
177.04(7)/171.81(7)
100.1(1)
169.1(1)
84.1(2)
89.7(2)
173.4(2)
86.6(2)
P–Pd–O2
P–Pd–C6
O1–Pd–O2
O1–Pd–C6
O2–Pd–C6
The corresponding values of the second part of the molecule (1a) or a second crystallographically independent molecule in the asymmetric unit (7b) are
shown in italic.

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A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
Ac
O
O
O
1
+ Hacac
/
2
Pd
Pd
O
O
- HOAc
2
P
P
ArO OAr
ArO OAr
1a
10
Ar = 2,4-(
t-Bu)2C6H3
Ac
O
O
1
Pd
P
+ Hacac
- HOAc
/
Pd
2
2
P
O
t-Bu
t-Bu
t-Bu
t-Bu
1c
11
Fig. 2. ORTEP style plot [30h] of compound 7b in the solid state. Thermal
ellipsoids are drawn at the 50% probability level. Hydrogen atoms are
omitted for clarity.
Scheme 4. Synthesis of acetylacetonate phospha- and phosphite-
palladacycles.
˚
length is shorter in complex 7b (2.1590(7), 2.1554(7) A)
˚
compared to 1a (2.1630(6), 2.1535(6) A) and 1b (2.1668
˚
(17) A). The Pd–C(1) bond lengths for complex 7b are within
the esd for carbene-substituted phosphitepalladacycles. The
heterocyclic five-membered ring in complex 7b [Pd1(2)–
C7(57)–C8(58)–O1(4)–P1(2)] adopts an envelope confor-
mation, with bond angles similar to those observed in the
saturated carbene complexes [23].
2.3. Acetylacetonates of phospha- and
phosphitepalladacycles
It is well established that acetylacetonate substituted
palladacycles show very high turnover numbers (TONs)
in the Mizoroki-Heck coupling reactions of iodobenzene
with styrene, therefore the preparation and characteriza-
tion of new phospha- and phosphitepalladacycles has been
performed in this work.
The acetylacetonate phospha/phosphitepalladacycles
were prepared by treatment of the acetate bridged pallada-
cycles 1a and 1c with 2,4-pentanedione (Hacac) in dichlo-
romethane to afford the acetylacetonate products 10 and
11 in nearly quantitative yields according to established
methods [1,9,17] (Scheme 4). In a previous report it was
mentioned that the acetylacetonate substituted palladacy-
cle 11 (Fig. 3) shows high TONs of 3500 [mole product
per mole 11] in Mizoroki–Heck coupling reactions for the
coupling of chlorobenzene with styrene [9].
Fig. 3. ORTEP style plot [30h] of compound 11 in the solid state. Thermal
ellipsoids are drawn at the 50% probability level. Hydrogen atoms are
omitted for clarity.
for complex 11 that the two Pd–O distances differ signifi-
cantly. The oxygen atom O1 coordinated trans to the
carbon atom shows
(2.111(4) A) compared to the oxygen atom O2 coordinated
trans to the phosphine (2.092(4) A), because of the donat-
a slightly longer bond length
˚
The compounds 10 and 11 show broad 1H NMR signals
at 25 ꢁC [9]. Acetylacetonate complexes of phospha- and
phosphitepalladacycles show excellent air and thermal sta-
bility even at elevated temperatures. The structure of com-
plex 11 was determined by single-crystal X-ray diffraction
studies. Suitable single were grown from dichloromethane
by slow evaporation of the solvent at ambient temperature
(Fig. 3).
˚
ing effect of the carbanion. This behaviour was observed
for the first time for the di-ortho-tolyl-substituted pallada-
cycle complex (C26H27O2PPd) with bond lengths of 2.112
˚
and 2.078 A [28].
3. Conclusion
According to previously described solid state structures
of acetylacetonate-substituted palladacycles [9], we found
The compounds 1a,b make excellent precursors for the
generation of both mono- and di-substituted carbene

A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
3321
adducts of phosphitepalladacycles in good yields. New
NHC-substituted phosphitepalladacycles were prepared
using a similar procedure to that used to prepare NHC
substituted phosphine complexes, in order to investigate
their chemical properties. Acetylacetonate complexes of
phospha- and phosphitepalladacycles show excellent air
and thermal stability even at elevated temperatures. The
structural identity of three compounds was settled by sin-
gle-crystal X-ray diffraction studies. We are currently
investigating the catalytic activity of these complexes in dif-
ferent types of CC-coupling reactions, and this work will be
reported at a later date.
125.5, 124.6, 122.0 (CAryl), 35.4, 35.2, 32.2, 31.9, 30.9, 29.9
(CH3), 21.5 (CO2CH3). 31P{1H} NMR (161 MHz, THF-
d8): d = 126.7 (s), 124.8 (s) (I = 1:1). MS (CI) m/z (%):
1622.7 (10, [M+]), 1563.5 (65, [M+ꢀOAc]), 1386.7 (40,
[M+ꢀ2,4-di-t-Bu-C6H5O]), 976.3 (35, [M+ꢀ(2,4-di-t-Bu-
C6H5O)3]), 810.6 (100, [12palladacycle]), 751 (50, [(2,4-di-t-
Bu-C6H5O)3PPd]), 441.5 (20, [(2,4-di-t-Bu-C6H5O)2P+]),
191.3 (10, [2,4-di-t-Bu-C6H5+]). Anal. Calc. for C88H130
-
O10P2Pd2 Æ THF (1694.86): C, 65.20; H, 8.21. Found: C,
66.20; H, 7.98%.
4.3. Acetato-(1,3-di-tert-butylimidazolin-2-ylidene)
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-
di-tert-butylphenyl-jC}palladium(II) (2a)
4. Experimental
4.1. General comments
To a suspension of 300 mg (0.19 mmol) trans-di(l-ace-
tato)-bis[2-[[bis[2,4-bis(1,1-dimethylethyl)phenoxy]phos-
phino-jP]oxy]-3,5-bis(1,1-dimethylethyl)phenyl-jC]dipal-
ladium(II) (1a) in 10 mL toluene, a solution of 100 mg
(0.55 mmol) 1,3-di-tert-butylimidazolin-2-ylidene 2 in 7 mL
THF was added at ꢀ70 ꢁC. The reaction mixture was
slowly warmed to room temperature and stirred for 3 h.
After 30 min a clear solution was obtained. The solvent
was removed in vacuo and the residue was washed twice
with 5 mL n-hexane. Yield: 245 mg (0.25 mmol, 50%).
1H NMR (400 MHz, C6D6): d = 8.44 (1H, s), 8.07 (1H,
The precursors 1b [17], and free carbenes and azolium
salts (2–9) were prepared according to the literature [29].
1H, 13C and 31P NMR spectra were recorded on a JEOL-
JMX-GX 270 or 400 MHz spectrometer at room tempera-
ture and referenced to the residual H and 13C signals of
1
the solvents or 85% H3PO4 as an external standard (31P).
NMR multiplicities are abbreviated as follows: s = singlet,
d = doublet, t = triplet, sept. = septet, m = multiplet, br. =
broad signal. Coupling constants J are given in Hz. Ele-
mental analyses were carried out by the Microanalytical
3
d, JHH = 7.2 Hz), 7.55 (1H, s), 7.45 (1H, s), 7.29 (1H, d,
Laboratory at the TU Munchen. Mass spectra were per-
¨
formed at the TU Munchen Mass Spectrometry Labora-
¨
tory on a Finnigan MAT 90 spectrometer using CI or
FAB techniques. Melting points were measured with a
Buchi melting point apparatus system (Dr. Tottoli).
¨
3JHH = 7.6 Hz), 7.03 (1H, s), 6.66 (1H, s), 6.60 (1H, s),
6.51 (2H, s, NCHCHN), 2.42 (3H, s, OAc), 1.65 (9H, s,
C(CH3)3), 1.58 (9H, s, C(CH3)3), 1.43 (9H, s, C(CH3)3),
1.37 (9H, s, C(CH3)3), 1.32 (9H, s, C(CH3)3), 1.31 (9H, s,
C(CH3)3), 1.13 (9H, s, C(CH3)3), 0.97 (9H, s, C(CH3)3).
13C{1H} NMR (100 MHz, C6D6): d = 175.7 (d, NCN,
JPC = 16.8 Hz), 154.7 (s, C6H5), 153.9, 153.7 (s, C6H5),
148.4, 148.3 (s, C6H5), 146.4, 144.8 (s, C6H5), 142.1,
140.3, 138.3 (s, C6H5), 135.6, 134.9, 131.8, 131.5 (s,
C6H5), 131.0 (s, OCO), 124.2, 124.0, 123.5, 123.4 (s,
C6H5), 123.1, 120.3, 119.6, 118.7 (s, C6H5), 116.7
(NCHCHN), 60.0 (NC(CH)3), 35.0, 34.9, 34.7, 34.3, 34.2
(s, C(CH3)3), 31.2 (d, C(CH3)3, JPC = 9.2 Hz), 30.4 (s,
C(CH3)3), 30.2 (s, C(CH3)3), 29.7 (d, C(CH3)3,
JPC = 12.2 Hz), 29.5 (s, C(CH3)3). 31P{1H} NMR
(161 MHz, C6D6): d = 136.9 (s), 135.9 (s); (I = 5:1). MS
(FAB) m/z (%): 930.2 (100, [M+ꢀOAc]), 286.8 (50,
[Pd+carbene]), 228.8 (45, [Pd+carbeneꢀt-Bu]), 181 (58,
[carbene]), 123 (50, [carbeneꢀt-Bu]). Anal. Calc. for
C55H86N2O5PPd (992.53): C, 66.55; H, 8.73; N, 2.82.
Found: C, 66.37; H, 8.99; N, 2.17%.
4.2. trans-Di(l-acetato)-bis[2-[[bis[2,4-di-tert-
butylphenoxy]phosphino-jP]oxy]-3,5-di-tert-butylphenyl-
jC]dipalladium(II) (1a)
To a solution of 750 mg (3.34 mmol) Pd(OAc)2 dissolved
in 50 mL monomethylglycol ether, 2.38 g (3.68 mmol)
tri[2,4-di-tert-butylphenyl]phosphite was added and heated
for 2 h at 80 ꢁC. After 10 min. a colorless product started to
precipitate from the solution. The solution was cooled to
room temperature and the solvent was removed by filtra-
tion, the solid was washed with the same amount of 5 mL
monomethylglycol ether, toluene and n-hexane. The
obtained product 1a is soluble in THF and DCM. Yield:
252 mg (1.55 mmol, 93%).
M.p. 247–248 ꢁC. 1H NMR (400 MHz, (CD3)2SO):
3
d = 7.80 (2H, d, JHH = 9.2 Hz), 7.34 (2H, s), 7.23 (2H, t,
3
3JHH = 8.0 Hz), 7.16 (2H, d, JHH = 6.6 Hz), 7.12 (2H, s),
4.4. Chloro-(1,3-di-tert-butylimidazolin-2-ylidene)
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-
di-tert-butylphenyl-jC}palladium(II) (2b)
3
6.97 (2H, t, JHH = 9.6 Hz), 6.84 (2H, s), 6.67 (2H, d,
3JHH = 8.4 Hz, CHAryl), 1.84 (6H, s, CO2CH3), 1.40 (18H,
s, C(CH3)3), 1.33 (18H, s, C(CH3)3), 1.23 (18H, s,
C(CH3)3), 1.21 (18H, s, C(CH3)3), 1.20 (18H, s, C(CH3)3),
1.15 (18H, s, C(CH3)3). 13C{1H} NMR (100 MHz, THF-
d8): d = 152.4 (CO2CH3), 148.9 (d, CAryl, JPC = 5.4 Hz),
147.8, 139.8, 135.5, 133.5, 131.5, 129.7, 128.9, 126.0,
To a suspension of 300 mg (0.19 mmol) trans-di
(l-chloro)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II) (1b)
in 10 mL toluene, a solution of 100 mg (0.55 mmol)

3322
A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
1,3-di-tert-butylimidazolin-2-ylidene 2 in 7 mL THF was
added at ꢀ70 ꢁC. The reaction mixture was stirred at room
temperature for 3 h. After 30 min a clear solution was
obtained. The solvent was removed in vacuo and the resi-
due was washed twice with 5 mL n-hexane. Yield: 273 mg
(0.26 mmol, 61%).
(19, [M+ꢀOAc]), 305.0 (100, [carbene]), 189.0 (45, [2,4-di-
t-Bu-C6H5]). Anal. Calc. for C65H89N2O5PPd (1115.81):
C, 69.97; H, 8.04; N, 2.51. Found: C, 69.40; H, 8.21; N,
2.41%.
4.6. Chloro-(1,3-di-mesitylimidazolin-2-ylidene)
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-
di-tert-butylphenyl-jC}palladium(II) (3b)
1H NMR (400 MHz, C6D6): d = 8.34 (1H, s), 8.08 (1H,
s), 7.48 (2H, s), 7.43 (2H, s), 7.30 (1H, s), 6.78 (1H, d,
3JHH = 7.6 Hz), 6.51 (2H, s, NCHCHN), 1.75 (9H, s,
C(CH3)3), 1.61 (9H, s, C(CH3)3), 1.53 (9H, s, C(CH3)3),
1.46 (9H, s, C(CH3)3), 1.39 (9H, s, C(CH3)3), 1.32 (9H, s,
C(CH3)3), 1.19 (9H, s, C(CH3)3), 1.07 (9H, s, C(CH3)3).
13C{1H} NMR (100 MHz, C6D6): d = 177.5 (d, NCN,
JPC = 16.8 Hz), 163.7, 161.3, 155.6, 148.9, 146.7, 144.8,
140.7, 138.9, 138.1, 135.1, 133.5, 124.6, 123.9, 122.8,
122.2, 121.2, 120.1, 119.1, 117.4 (NCHCHN), 68.1
(NC(CH)3), 35.8, 35.1, 35.0, 34.9, 34.5, 34.1, 34.1
(C(CH3)3), 32.5 (d, C(CH3)3, JPC = 7.7 Hz), 31.8, 30.4,
30.1 (d, C(CH3)3, JPC = 9.2 Hz), 30.1 (d, C(CH3)3,
JPC = 9.2 Hz). 31P{1H} NMR (161 MHz, C6D6):
d = 141.1 (s), 135.9 (s); (I = 1:8). MS (FAB) m/z (%):
931.3 (22, [M+ꢀCl]), 751.1 (7, [1/2palladacycleꢀCl]),
284.7 (27, [Pd+carbene]), 180.9 (100, [carbene]). Anal.
Calc. for C53H83N2O3PPdCl (967.49): C, 65.69; H, 8.63;
N, 2.89. Found: C, 65.28; H, 8.44; N, 2.57%.
To a suspension of 300 mg (0.19 mmol) trans-di
(l-chloro)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II) (1b) in
15 mL toluene, a solution of 152 mg (0.49 mmol) 1,3-di-
mesitylimidazolin-2-ylidene 3 in 10 mL THF was added
at ꢀ90 ꢁC. The reaction mixture was stirred at room tem-
perature for 2 h. After 30 min a clear solution was
obtained. The solvent was removed in vacuo and the resi-
due was washed with 5 mL n-hexane and 5 mL n-pentane.
Yield: 398 mg (0.37 mmol, 72%).
3
1H NMR (400 MHz, C6D6): d = 7.65 (2H, dd, JHH
=
4
3
7.9 Hz, JHH = 2.0 Hz), 7.44 (1H, dd, JHH = 5.59 Hz,
3
4JHH = 2.3 Hz), 7.03 (2H, dd, JHH = 7.9 Hz), 6.92 (1H,
3
4
dd, JHH = 10.7 Hz, JHH = 2.0 Hz), 6.74 (2H, br. s, mesi-
tyl), 6.65 (2H, br. s, mesityl), 6.34 (2H, dd, 3JHH = 10.7 Hz,
4JHH = 2.3 Hz), 3.59 (2H, m, NCHCHN), 2.69 (6H, s,
CH3), 2.37 (6H, s, CH3), 2.12 (6H, s, CH3), 1.48 (9H, s,
C(CH3)3), 1.28 (18H, s, C(CH3)3), 1.18 (18H, s, C(CH3)3),
1.11 (9H, s, C(CH3)3). 13C{1H} NMR (100 MHz, C6D6):
no signal was detected for the carbene carbon nucleus,
d = 167.5 (s, CAryl), 163.1, 159.9 (s, CAryl), 152.3 (d,
4.5. Acetato-(1,3-di-mesitylimidazolin-2-ylidene)
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-
di-tert-butylphenyl-jC}palladium(II) (3a)
Three hundred milligrams of (0.19 mmol) trans-di-
(l-acetato)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
JPC = 21.2 Hz), 147.1, 146.9, 144.6, 140.2 (d, CAryl,
JPC = 5.4 Hz), 140.0, 139.5 (d, CAryl, JPC = 4.6 Hz), 148.9,
148.4, 147.5, 146.7, 145.9, 139.2, 136.3, 132.1, 130.8, 129.8,
129.1, 125.5, 124.5, 124.4, 121.3, 120.5 (d, NCHCHN,
4JPC = 6.9 Hz), 35.3, 35.1, 34.6, 34.4, 34.3 (s,C(CH3)3),
31.7, 30.6, 30.5, 29.7 (s, C(CH3)3), 24.0, 21.2, 18.0 (s, CH3).
31P{1H} NMR (109 MHz, C6D6): d = 121.3 (s), 133.7(s);
(I = 1:2). MS (FAB) m/z (%): 1057.5 (10, [M+ꢀCl]), 751.4
(5, [M+ꢀ(Cl+carbene)]), 645.4 (5, [P(OC6H2-2,4-t-Bu2])),
305.0 (100, [carbene]), 189.0 (45, [2,4-di-t-Bu-C6H5]). Anal.
Calc. for C63H86N2O3PPdCl (1092.22): C, 69.28; H, 7.94;
N, 2.56. Found: C, 69.31; H, 7.93; N, 2.48%.
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II)
(1a),
30 mg (0.36 mmol) sodium acetate and 144 mg (0.37 mmol)
1,3-di-mesitylimidazolium tetrafluoroborate 8 were sus-
pended in 5 mL DMSO and heated for 2 h at 90 ꢁC. The vol-
atile compounds were removed in vacuo and the residue was
extracted three times with 4 mL toluene to obtain a yellow
product. Yield: 246 mg (0.22 mmol, 60%).
3
1H NMR (400 MHz, C6D6): d = 8.15 (2H, d, JHH
=
7.9 Hz), 8.04 (1H, br. s), 7.44 (2H, br. s), 6.99 (1H, dd,
4
3JHH = 10.1 Hz, JHH = 2.4 Hz), 6.61 (2H, br. s, mesityl),
6.65 (2H, br. s, mesityl), 6.53 (2H, br s), 3.81 (2H, m,
NCHCHN), 2.32 (6H, s, CH3,mesityl), 2.21 (6H, s, CH3,mesityl),
2.03 (6H, s, CH3,mesityl), 1.95 (9H, s, C(CH3)3), 1.78 (18H,
s, C(CH3)3), 1.75 (9H, br. s, C(CH3)3), 1.44 (9H, s,
C(CH3)3), 1.23 (9H, s, C(CH3)3). 13C{1H} NMR
4.7. Chloro-(1-mesityl-3-methylimidazolin-2-ylidene)
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-
di-tert-butylphenyl-jC}palladium(II) (4b)
(100 MHz, C6D6): d = 182.1 (s, NCN), 163.6 (d, Cmetallated
,
To a suspension of 300 mg (0.19 mmol) trans-di
(l-chloro)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II) (1b) in
15 mL toluene, a solution of 100 mg (0.49 mmol) 1-mesi-
tyl-3-methylimidazolin-2-ylidene 4 in 10 mL THF was
added at ꢀ85 ꢁC. The reaction mixture was stirred at room
temperature for 2 h. After 30 min a clear solution was
obtained. The solvent was removed in vacuo and the resi-
due was washed twice with 5 mL n-pentane. Yield:
424 mg (0.43 mmol, 86%).
2JPC = 18.1 Hz), 148.9, 147.6 (s, CAryl), 139.8, 138.3, 136.9,
136.5, 132.6, 131.6, 130.2 (d, CAryl, JPC = 7.4 Hz), 126.0,
125.3 (d, CAryl, JPC = 4.6 Hz), 124.9, 124.8, 124.4, 122.5,
121.5, 119.7, 119.6, 115.9 (s, CAryl), 50.2 (s, NCHCHN),
40.8, 35.7, 35.6, 35.5, 35.4, 34.8 (s, C(CH3)3), 32.4, 31.9,
31.7, 30.7, 30.4, 29.8 (s, C(CH3)3), 21.7, 21.2, 18.5, 18.1
(s, CH3). 31P{1H} NMR (109 MHz, C6D6): d = 134.1(s),
133.1 (s); (I = 2:1). MS (FAB) m/z (%): 1115.2 (5, [M+]),
1101.1 (18, [M+ꢀCH3]), 1086.1 (5, [M+ꢀOCH3]), 1056.4

A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
3323
1H NMR (400 MHz, C6D6): d = 9.28 (2H, dd,
3JHH = 8.5 Hz), 7.91 (1H, d, JHH = 8.56 Hz), 7.46 (2H,
(C(CH3)3), 31.8, 31.5, 31.4, 30.6, 30.5, 30.1 (C(CH3)3).
31P{1H} NMR (161 MHz, (CD3)2SO): d = 139.5 (s), 138.3
(s); (I = 1:4). 31P{1H} NMR (109 MHz, C6D6): d = 139.9
(s), 138.9 (s); (I = 1:4). MS (FAB) m/z (%): 998.5 (11,
[M+]), 353.6 (12, [Pd+carbene]), 246.8 (43, [carbene]),
166.8 (100, [carbeneꢀPh]). Anal. Calc. for C61H81N2O5PPd
(1059.72): C, 69.14; H, 7.70; N, 2.64. Found: C, 69.34; H,
7.68; N, 2.67%.
3
4
dd, JHH = 9.6 Hz, JHH = 2.4 Hz), 7.33 (1H, br. t,
3
JHH = 4.0 Hz), 6.68 (2H, br. d, JHH = 8.4 Hz, CHAryl),
6.32 (2H, br. s, mesityl), 3.54 (2H, m, NCHCHN), 1.78
(3H, s, CH3), 1.66 (6H, s, CH3), 1.52 (6H, s, CH3), 1.49
(6H, s, CH3), 1.32 (9H, s, C(CH3)3), 1.26 (18H, s,
C(CH3)3), 1.13 (18H, s, C(CH3)3), 0.87 (9H, s, C(CH3)3).
13C{1H} NMR (100 MHz, C6D6): d = 186.2 (s, NCN),
179.9 (d, JPC = 14.8 Hz), 154.5 (d, JPC = 16.5 Hz), 149.0
(d, CAryl, JPC = 6.5 Hz), 148.8, 148.0, 147.7, 146.7, 146.3,
144.1, 141.2 (s, CAryl), 139.6 (d, CAryl, JPC = 5.5 Hz),
138.5, 138.2, 137.7, 136.1, 135.2, 134.5, 133.9 (s, CAryl),
129.8 (d, CAryl, JPC = 11.4 Hz), 125.6, 124.5, 123.9, 121.8
(s, CAryl), 121.3 (d, CAryl, JPC = 6.7 Hz), 120.6 (d,
NCHCHN, JPC = 8.2 Hz), 35.5, 35.3, 34.5, 34.3 (s,
C(CH3)3), 32.2, 31.9, 31.8, 31.5, 31.3 (s, C(CH3)3), 21.2,
20.3, 19.6, 19.3, 18.8 (s, CH3,mesityl), 14.2 (s, CH3).
31P{1H} NMR (109 MHz, C6D6): d = 138.5 (s), 137.3 (s);
(I = 1:3). MS (FAB) m/z (%): 951.5 (10, [M+ꢀCl]), 543.2
4.9. Chloro-(1-diphenylmethyl-3-methylimidazolin-2-
ylidene){2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]
oxy]-3,5-di-tert-butylphenyl-jC}palladium(II) (5b)
To a suspension of 394 mg (0.25 mmol) trans-di
(l-chloro)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II) (1b) in
15 mL toluene, a solution of 200 mg (0.55 mmol) 1-diphe-
nylmethyl-3-methylimidazolin-2-ylidene 5 in 10 mL THF
was added at ꢀ90 ꢁC. The reaction mixture was stirred at
room temperature for 3 h. After 30 min a clear solution
was obtained. The solvent was removed in vacuo and the
residue was washed twice with 5 mL n-hexane. Yield:
(5,
[(2,4-di-t-Bu-C6H5-O)2PPd]),
333.2
(8,
[car-
bene+Pd+P]), 306.0 (8, [carbene+Pd]), 199.1 (100, [car-
bene]), 185.0 (10, [carbeneꢀMe]). Anal. Calc. for
C55H78N2O3PPdCl (988.07): C, 66.86; H, 7.96; N, 2.84.
Found: C, 66.07; H, 7.97; N, 2.25%.
282 mg (0.27 mmol, 63%).
3
1H NMR (270 MHz, C6D6): d = 8.43 (1H, dd, JHH
=
4
3
8.7 Hz, JHH = 2.0 Hz), 8.33 (1H, dd, JHH = 8.4 Hz,
4JHH = 1.7 Hz), 7.91 (1H, s), 7.53 (2H, dd, 3JHH = 10.6 Hz,
3
4
4.8. Acetato-(1-diphenylmethyl-3-methylimidazolin-2-ylidene)-
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]-
oxy]-3,5-di-tert-butylphenyl-jC}palladium(II) (5a)
4JHH = 2.0 Hz), 7.40 (2H, dd, JHH = 6.7 Hz, JHH
=
1.8 Hz), 7.23 (1H, s), 7.12–6.93 (10H, m, CHAryl), 6.38
3
(1H, t, JHH = 1.7 Hz, NCH), 6.20 (1H, s, NCHCHN),
3
6.16 (1H, t, JHH = 1.7 Hz, NCHCHN), 3.32 (3H, s,
Three hundred and fifty-four milligrams of (0.22 mmol)
trans-di(l-acetato)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phos-
phino-jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II)
(1a), 60 mg (0.73 mmol) sodium acetate and 150 mg
(0.30 mmol) imidazolium tetrafluoroborate salt 9 were sus-
pended in 5 mL DMSO and heated for 2 h at 80 ꢁC. The vol-
atile compounds were removed in vacuo and the residue was
extracted three times with 4 mL toluene to obtain a yellow
NCH3), 1.70 (9H, s, C(CH3)3), 1.49 (9H, s, C(CH3)3), 1.39
(9H, s, C(CH3)3), 1.21 (9H, s, C(CH3)3), 1.11 (9H, s,
C(CH3)3), 1.08 (9H, s, C(CH3)3). 13C{1H} NMR
(100 MHz, C6D6): d = 186.1 (NCN), 154.0 (d, CAryl
,
JPC = 27.5 Hz), 149.1, 146.8 (d, CAryl, JPC = 6.7 Hz),
144.5, 139.7, 137.3 (d, CAryl, JPC = 6.2 Hz), 134.8, 133.7 (d,
CAryl, JPC = 16.6 Hz), 129.8, 128.8, 128.7, 128.6, 128.5,
128.2, 124.5 (d, CAryl, JPC = 5.7 Hz), 124.2 (d, CAryl
,
product. Yield: 273 mg (0.26 mmol, 60%).
JPC = 6.2 Hz), 121.6 (NCHCHN), 121.2 (NCHCHN), 67.6
(NCH), 38.0 (NCH3), 35.5, 35.4, 35.3, 34.6, 34.5, 34.2
(C(CH3)3), 31.8, 31.6, 31.5, 30.8, 30.6, 30.1 (C(CH3)3), 23.6
(CO2CH3). 31P{1H} NMR (161 MHz, (CD3)2SO):
d = 140.2 (s). 31P{1H} NMR (109 MHz, C6D6): d = 138.8
(s), 137.6 (s); (I = 8.5:1). MS (FAB) m/z (%): 998.4 (15,
[M+]), 353.6 (15, [Pd+carbene]), 246.8 (59, [carbene]),
3
1H NMR (400 MHz, C6D6): d = 8.57 (1H, dd, JHH
=
4
3
8.7 Hz, JHH = 2.2 Hz), 7.91 (1H, dd, JHH = 8.4 Hz,
4JHH = 1.2 Hz), 7.56 (2H, s), 7.53 (1H, dd, JHH = 8.8 Hz,
3
4JHH = 2.2 Hz), 7.41 (2H, s), 7.29 (1H, s), 7.28 (1H,
4
d, JHH = 2.4 Hz), 7.12–6.93 (7H, m, CHAryl), 6.84 (2H, d,
JHH = 1.8 Hz), 6.30 (1H, s, NCH), 6.24 (1H, d,
4JHH = 1.0 Hz, NCHCHN), 6.05 (1H, s, NCHCHN), 3.76
(3H, s, NCH3), 2.10 (3H, s, CO2CH3), 1.52 (9H, s,
C(CH3)3), 1.40 (9H, s, C(CH3)3), 1.38 (9H, s, C(CH3)3),
1.21 (9H, s, C(CH3)3), 1.15 (9H, s, C(CH3)3), 1.01 (9H, s,
C(CH3)3). 13C{1H} NMR (100 MHz, C6D6): d = 185.2 (s,
NCN), 176.5 (s, CO2CH3), 155.3, 154.8, 154.5, 149.2, 149.0
166.8
(100,
[carbeneꢀPh]).
Anal.
Calc.
for
C59H78N2O3PPdCl (1036.11): C, 68.39; H, 7.59; N, 2.70.
Found: C, 68.23; H, 7.43; N, 2.65%.
4.10. Bis(1,3-di-cyclohexylimidazolin-2-ylidene){2-
[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-di-
tert-butylphenyl-jC}palladium(II) acetate (6a)
(d, CAryl, JPC = 6.2 Hz), 147.1, 146.9, 144.6, 140.2 (d, CAryl
,
JPC = 5.4 Hz), 140.0, 139.5 (d, CAryl, JPC = 4.6 Hz), 139.4,
137.8, 135.1, 129.3, 129.1, 129.1, 128.9, 128.7, 128.5, 128.4,
To a suspension of 300 mg (0.19 mmol) trans-di
(l-acetato)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II) (1a)
in 15 mL toluene, a solution of 128 mg (0.55 mmol)
125.6, 124.8, 124.7, 124.5, 124.1, 123.7, 123.4, 122.2 (d, CAryl
,
JPC = 24.4 Hz), 121.3, 118.8 (d, NCHCHN, JPC = 21.2 Hz),
68.0 (NCH), 38.5 (NCH3), 35.4, 35.3, 35.1, 34.6, 34.4, 34.3

3324
A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
1,3-di-cyclohexylimidazolin-2-ylidene 6 in 10 mL THF was
added at ꢀ80 ꢁC. The reaction mixture was stirred at room
temperature for 3 h. After 30 min a clear solution was
obtained. The solvent was removed in vacuo and the resi-
due was washed twice with 5 mL n-hexane and 5 mL n-pen-
tane. Yield: 346 mg (0.27 mmol, 49%).
CAryl), 119.5 (d, CAryl, JPC = 8.5 Hz), 118.5 (NCHCHN),
60.1 (br. s, CHCy), 59.3 (br. s, CHCy), 35.0, 34.8, 34.6,
34.3 (C(CH3)3), 33.1–31.3(CH2,Cy), 30.2, 30.1, 29.7, 29.5
(C(CH3)3), 26.4 (CO2CH3), 25.0, 24.9, 24.5, 24.4
(C(CH3)3). 31P{1H} NMR (109 MHz, C6D6): d = 141.0
(s). MS (FAB) m/z (%): 1215.5 (40, [M+ꢀCl]), 983.3 (35,
[M+ꢀ(Cl+1NHC])), 336.9 (15, [Pd+carbene]), 233.1 (100,
[carbene]), 151.8 (42, [carbeneꢀCy]). Anal. Calc. for
C72H110N4O3PPdCl (1252.52): C, 69.04; H, 8.85; N, 4.47.
Found: C, 69.23; H, 8.64; N, 3.98%.
1H NMR (400 MHz, CDCl3): d = 9.28 (2H, d,
3
JHH = 6.4 Hz), 8.49 (1H, t, JHH = 8.4 Hz), 7.55 (2H, br.
3
4
dd, JHH = 9.6 Hz, JHH = 2.7 Hz, CHAryl), 7.05 (1H, br.
3
3
t, JHH = 8.4 Hz, CHAryl), 6.68 (2H, br. d, JHH = 8.4 Hz,
CHAryl), 6.54 (m, NCHCHN), 6.41 (m, NCHCHN), 4.94
(2H, t, 3JHH = 10.6 Hz, CHCy), 4.08 (2H, t, 3JHH = 4.7 Hz,
CHCy), 1.78–1.41 (br. m, CH2,Cy) 1.36 (9H, s, C(CH3)3),
1.21 (18H, s, C(CH3)3), 0.61 (18H, s, C(CH3)3), 0.39 (9H,
s, C(CH3)3). 13C{1H} NMR (100 MHz, CDCl3):
d = 178.4 (s, NCN), 176.8 (s, CO2CH3), 164.1, 161.3,
148.6, 147.0 (s, CAryl), 146.1 (d, CAryl, JPC = 3.9 Hz),
145.3, 143.1 (s, CAryl), 138.7 (d, CAryl, JPC = 5.7 Hz),
136.1, 133.4, 132.4, 132.2, 130.9 (s, CAryl), 126.7, 126.2,
125.3, 124.3, 121.9 (s, CAryl), 120.9 (d, CAryl, JPC = 6.7 Hz),
118.4 (s, CAryl), 117.4 (s, NCHCHN), 116.5 (s, NCHCHN),
69.4 (br, NCHCy), 58.1 (br, NCHCy), 34.1, 33.9, 33.7 (s,
CH2,Cy), 31.9, 31.6, 30.4, 30.8 (s, C(CH3)3), 29.2, 29.0,
28.7, 28.6 (s, C(CH3)3), 25.8 (CO2CH3), 24.3–23.6 (br,
CH2,Cy). 31P{1H} NMR (109 MHz, C6D6): d = 139.4 (s).
MS (FAB) m/z (%): 1215.5 (40, [M+ꢀOAc]), 983.3 (35,
[M+ꢀ(OAc+1NHC])), 337.1 (15, [Pd+carbene]), 233.1
(100, [carbene]), 151.8 (42, [carbeneꢀCy]). Anal. Calc. for
C74H113N4O5PPd Æ 1/2CH2Cl2 (1318.58): C, 67.86; H,
8.71; N, 4.25. Found: C, 68.44; H, 8.83; N, 3.22%.
4.12. Acetato-(1,3-di-methylimidazolin-2-ylidene)
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-
di-tert-butylphenyl-jC}palladium(II) (7a)
To a suspension of 101 mg (0.125 mmol) trans-di
(l-acetato)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II) (1a) in
15 mL toluene, a solution of 48 mg (0.55 mmol) 1,3-di-
methylimidazolin-2-ylidene 7 in 10 mL THF was added
at ꢀ90 ꢁC. The reaction mixture was stirred at room tem-
perature for 4 h. After 30 min a clear solution was
obtained. The solvent was removed in vacuo and the resi-
due was washed twice with 5 mL n-hexane. Yield: 198 mg
(0.19 mmol, 79%).
1H NMR (270 MHz, C6D6): d = 8.45 (2H, d,
3
JHH = 4.3 Hz), 7.91 (1H, t, JHH = 6.3 Hz), 7.43 (2H, br.
3
d, JHH = 8.6 Hz), 7.31 (1H, br. t, JHH = 2.5 Hz), 6.57
3
(2H, d, JHH = 7.3 Hz), 3.16 (2H, s, NCHCHN), 1.58
(6H, s, CH3), 1.42 (9H, s, C(CH3)3), 1.33 (18H, s,
C(CH3)3), 1.16 (18H, s, C(CH3)3), 1.08 (9H, s, C(CH3)3).
13C{1H} NMR (100 MHz, C6D6): d = 178.3 (NCN),
170.1 (CO2CH3), 154.9, 148.6, 147.5 (s, CAryl), 145.5,
140.6, 139.2, 139.2, 135.1, 132.5, 125.8, 125.4 (s, CAryl),
124.6 (t, CAryl, JPC = 7.9 Hz), 124.3, 124.2, 123.8, 123.3
4.11. Bis(1,3-di-cyclohexylimidazolin-2-ylidene)
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-
di-tert-butylphenyl-jC}palladium(II) chloride (6b)
To
a
suspension of 300 mg (0.19 mmol) trans-di
(s, CAryl), 122.1, 121.5 (s, CAryl), 121.2 (d, CAryl,
(l-chloro)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II) (1b) in
15 mL toluene a solution of 128 mg (0.55 mmol) 1,3-di-
cyclohexylimidazolin-2-ylidene 6 in 10 mL THF was added
at ꢀ80 ꢁC. The reaction mixture was stirred at room tem-
perature for 3 h. The solvent was removed in vacuum
and the residue was washed twice with 5 mL n-hexane
and 5 mL n-pentane. Yield: 375 mg (0.29 mmol, 60%).
1H NMR (400 MHz, CDCl3): d = 9.49 (2H, d,
JPC = 10.4 Hz), 116.8 (s, NCHCHN), 70.8 (NCH), 36.7
(NCH3), 35.4, 35.3, 35.2, 35.1 (C(CH3)3), 31.8, 31.6, 31.5,
31.4 (C(CH3)3), 30.4, 30.1, 29.9, 29.8 (C(CH3)3). 31P{1H}
NMR (109 MHz, C6D6): d = 128.4 (s), 130.7 (s);
(I = 1:1). MS (FAB) m/z (%): 943.4 (55, [M+ꢀOAc]),
[M+ꢀ(OAc+NHC + CH3)]), 439.2 (5, [2,4-di-t-Bu-
C6H5OPPd + carbene]). Anal. Calc. for C49H73N2O5PPd
(907.51): C, 64.67; H, 8.11; N, 3.09. Found: C, 64.74; H,
8.22; N, 2.10%.
847.3
(100,
[M+ꢀ(OAc+NHC)]),
831.3
(10,
3
3JHH = 4.4 Hz), 8.26 (1H, d, JHH = 8.4 Hz), 7.85 (2H, d,
3
3JHH = 8.4 Hz), 7.47 (1H, br. t, JHH = 9.7 Hz, CHAryl),
3
6.52 (2H, d, JHH = 4.8 Hz, CHAryl), 6.43 (2H, br. s,
4.13. Chloro-(1,3-di-methylimidazolin-2-ylidene)
{2-[[bis[2,4-di-tert-butylphenoxy]phosphino-jP]oxy]-3,5-
di-tert-butylphenyl-jC}palladium(II) (7b)
3
NCHCHN), 4.92 (2H, t, JHH = 4.7 Hz, CHCy), 4.63 (2H,
3
t, JHH = 4.7 Hz, CHCy), 1.66 (9H, s, C(CH3)3), 1.46
(18H, s, C(CH3)3), 1.45 (9H, s, C(CH3)3), 1.42–1.31 (m,
20H, CH2,Cy), 1.23 (18H, s, C(CH3)3), 1.10 (9H, s,
C(CH3)3). 13C{1H} NMR (100 MHz, CDCl3): d = 175.1
(s, NCN), 173.0 (s, NCN), 171.0 (d, CAryl, JPC = 16.7 Hz),
153.5 (d, CAryl, JPC = 23.9 Hz), 148.2, 147.6, 147.2, 146.6,
146.0, 145.5 (s, CAryl), 141.5, 138.9, 134.3, 133.6 (s, CAryl),
133.5 (d, CAryl, JPC = 5.6 Hz), 124.9, 123.8, 123.2, 122.6 (s,
To a suspension of 200 mg (0.13 mmol) trans-di
(l-chloro)-bis[2-[[bis[2,4-di-tert-butylphenoxy]phosphino-
jP]oxy]-3,5-di-tert-butylphenyl-jC]dipalladium(II) (1b)
in 15 mL toluene, a solution of 48 mg (0.55 mmol) 1,3-
methylimidazolin-2-ylidene 7 in 10 mL THF was added
at ꢀ90 ꢁC. The reaction mixture was stirred at room

A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
3325
temperature for 4 h. After 30 min a clear solution was
4.15. Acetylacetonato-[o-(di-t-butylphosphino)-
benzyl]palladium(II) (11)
obtained. The solvent was removed in vacuo and the resi-
due was washed twice with 5 mL n-hexane. Yield: 185 mg
(0.19 mmol, 75%).
To a solution of 401 mg (0.5 mmol) acetate bridged
dimer 1c in 20 mL dichloromethane, 150 mg (1.5 mmol)
acetylacetone was added and the reaction mixture was stir-
red for 1 h at room temperature. The solvent was removed
in vacuo and the residue was washed with cold diethyl
ether. The product was recrystallized from dichlorometh-
ane as a colorless solid. Yield: 440 mg (0.99 mmol, 99.8%).
1H NMR (400 MHz, CDCl3): d = 7.43 (1H, t,
3JHH = 7.1 Hz, HAryl), 7.3–7.2 (2H, m, HAryl), 7.11 (1H,
1H NMR (270 MHz, C6D6): d = 8.31 (2H, d,
3JHH = 9.8 Hz), 7.68 (1H, d, JHH = 7.3 Hz), 7.39 (2H, br.
3
d, JHH = 9.1 Hz), 7.34 (1H, br. t, JHH = 3.1 Hz), 7.18
3
(2H, d, JHH = 7.3 Hz), 3.74 (1H, m, NCHCHN), 3.21
3
(1H, d, JHH = 10.8 Hz, NCHCHN), 1.76 (6H, s, CH3),
1.42 (9H, s, C(CH3)3), 1.32 (18H, s, C(CH3)3), 1.26 (18H,
s, C(CH3)3), 1.03 (9H, s, C(CH3)3). 13C{1H} NMR
(100 MHz, C6D6): d = 178.2 (d, JPC = 14.5 Hz, NCN),
154.8 (t, JPC = 23.9 Hz,CAryl), 148.6, 147.4, 145.8, 145.4,
140.9 (s, CAryl), 139.1 (d, CAryl, JPC = 5.2 Hz), 134.9,
134.2 (s, CAryl), 132.3 (d, CAryl, JPC = 18.4 Hz), 129.2,
125.6, 125.1, 124.9, 123.8, 122.13 (s, CAryl), 120.6 (d,
JPC = 10.2 Hz, NCHCHN), 67.5 (NCH), 36.4 (NCH3),
35.2, 34.9, 34.4, 34.3 (C(CH3)3), 32.0, 31.8, 31.5, 31.3
(C(CH3)3), 30.5, 30.2, 29.9, 29.8 (C(CH3)3). 31P{1H}
NMR (109 MHz, C6D6): d = 132.4 (s), 135.4 (s);
(I = 1:2). MS (FAB) m/z (%): 847.3 (100, [M+ꢀ(OAc+
NHC)]), 645.5 (10, [(2,4-di-t-Bu-C6H5O)3P]), 202.1 (8,
[Pd + NHC]). Anal. Calc. for C47H70N2O3PPdCl
(883.92): C, 63.77; H, 8.09; N, 3.17. Found: C, 63.72; H,
8.40; N, 3.58%.
3
t, JHH = 6.7 Hz, HAryl), 5.23 (1H, s, CHacac), 3.30 (2H,
d, JHH = 4.2 Hz, PdCH2), 1.93 (3H, s, CH3,acac), 1.36
(18H, d, JHH = 14 Hz, CH3,t-Bu). 13C{1H} NMR
(100 MHz, CDCl3): d = 189.0 (s, COacac), 187.9 (s, COacac),
160.9 (d, CAryl, JPC = 25 Hz), 134.8 (d, CAryl, JPC = 43 Hz),
133.2 (s, CAryl), 132.0 (s, CAryl), 130.2 (d, CAryl, JPC
=
21 Hz), 126.1 (d, CAryl, JPC = 7 Hz), 100.6 (s, CHacac),
38.2 (s, CH3,acac), 38.0 (s, CH3,acac), 31.4 (s, CH3,t-Bu).
31P{1H} NMR (161 MHz, CDCl3): d = 89.3 (s). MS
(FAB) m/z (%): 439.7 (12, [M+]), 340.7 (100, [M+ꢀacac]),
284.7 (17, [M+ꢀ(acac+t-Bu])), 240.7 (41, [M+ꢀ(acac+2t-
Bu])). Anal. Calc. for C20H31O2PPd (440.84): C, 54.49;
H, 7.09; P, 7.03; Pd 24.14. Found: C, 54.40; H, 7.10; P,
7.10; Pd 24.60%.
4.14. Acetylacetonato-{[bis[2,4-di-tert-butyl-
phenoxy]phosphino-P]oxy]-3,5-di-tert-butylphenyl-C}-
dipalladium(II) (10)
4.16. Single-crystal X-ray structure determination of
compounds 1a Æ (CH2Cl2), 7b Æ 3(CH2Cl2), and 11
To a solution of 405 mg (0.25 mmol) acetate bridged
dimer 1a in 20 mL dichloromethane 150 mg (1.50 mmol)
acetylacetone was added and the reaction mixture was stir-
red for 1 h at room temperature. The solvent was removed
in vacuo and the residue was washed with cold diethyl
ether. The product was recrystallized from dichlorometh-
ane as a pale yellow solid. Yield: 821 mg (0.96 mmol,
96.6%).
General: Crystal data and details of the structure deter-
mination are presented in Table 3. Suitable single crystals
for the X-ray diffraction studies were grown with standard
cooling techniques. Crystals were stored under perfluori-
nated ether, transferred in a Lindemann capillary, fixed,
and sealed. Preliminary examination and data collection
were carried out on an area detecting system (NONIUS,
MACH3, j-CCD) at the window of a rotating anode (NONIUS,
FR591) and graphite-monochromated Mo Ka radia-
1H NMR (400 MHz, CDCl3): d = 8.11 (1H, d,
JHH = 8.1 Hz, HAryl), 7.72 (2H, d,JHH = 8.6 Hz, HAryl),
7.51 (2H, d, JHH = 8.2 Hz, HAryl), 7.12 (1H, br. t,
JHH = 5.2 Hz), 7.03 (2H, m,HAryl), 5.27 (1H, s, CHacac),
2.06 (3H, s, CH3,acac), 1.66 (3H, s, CH3,acac), 1.36 (9H, s,
C(CH3)3), 1.29 (18H, s, C(CH3)3), 1.25 (18H, s, C(CH3)3),
1.03 (9H, s, C(CH3)3). 13C{1H} NMR (100 MHz, CDCl3):
˚
tion (k = 0.71073 A). The unit cell parameters were
obtained by full-matrix least-squares refinements during
the scaling procedure. Data collections were performed at
low temperatures (OXFORD CRYOSYSTEMS cooling device).
Each crystal was measured with a couple of data sets in
rotation scan modus with Du/Dx = 1.0ꢁ. Intensities were
integrated and the raw data were corrected for Lorentz,
polarization, and, arising from the scaling procedure for
latent decay and absorption effects. The structures were
solved by a combination of direct methods and difference
Fourier syntheses. All non-hydrogen atoms were refined
with anisotropic displacement parameters. Methyl hydro-
gen atoms were calculated as a part of rigid rotating
d = 187.9 (s, COacac), 186.9 (s, COacac), 148.2 (d, CAryl
JPC = 19.3 Hz), 146.8 (s, CAryl), 144.8 (s, CAryl), 139.0 (d,
JPC = 5.4 Hz, CAryl), 127.3 (s, CAryl), 124.4 (d, CAryl
,
,
JPC = 17.3 Hz), 123.7 (d, CAryl, JPC = 12.1 Hz), 122.0 (s,
CAryl), 119.8 (d, CAryl, JPC = 8.9 Hz), 99.6 (s, CHacac),
53.1 (s, CH3,acac), 45.9 (s, CH3,acac), 35.1, 35.0, 34.9, 34.5
(C(CH3)3), 31.8, 30.3, 29.7, 28.1 (C(CH3)3). 31P{1H}
NMR (161 MHz, CDCl3): d = 127.5 (s). MS (FAB) m/z
(%): 850.4 (38, [M+]), 751.4 (100, [M+ꢀacac]), 692.3 (17,
[M+ꢀ(acac+t-Bu])), 636.7 (41, [M+ꢀ(acac+2t-Bu])). Anal.
Calc. for C47H69O5PPd (851.44): C, 66.30; H, 8.17; P, 3.64;
Pd 12.46. Found: C, 66.21; H, 8.13; P, 3.78; Pd 12.80%.
˚
groups, with dC–H = 0.98 A and Uiso(H) = 1.5Ueq(C). All
other hydrogen atoms were placed in ideal positions and
refined using a riding model, with methylene and aromatic
˚
dC–H distances of 0.99 and 0.95 A, respectively, and Uiso
(H) = 1.2Ueq(C). Full-matrix least-squares refinements

3326
A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
Table 3
Crystallographic data for1a Æ (CH2Cl2), 7b Æ 3(CH2Cl2), and 11
Compound
1a Æ (CH2Cl2)
89H132Cl2O10P2Pd2
7b Æ 3(CH2Cl2)
11
Formula
Formula weight
Color/habit
C
C97H146Cl8N4O6P2Pd2
2022.56
Colorless/fragment
0.23 · 0.28 · 0.48
Triclinic
C20H31O2PPd
440.84
1707.63
Colorless/fragment
0.28 · 0.33 · 0.46
Triclinic
Colorless/plate
0.10 · 0.23 · 0.30
Orthorhombic
Pbca (no. 61)
8.4230 (3)
15.8029 (6)
31.2520 (15)
90
Crystal dimensions (mm)
Crystal system
Space group
ꢀ
ꢀ
P1 ðno:2Þ
P1 ðno:2Þ
˚
a (A)
15.3542 (1)
16.8517 (1)
18.4679 (2)
91.4991 (3)
95.5910 (3)
92.0949 (3)
4750.43 (7)
2
11.1224 (1)
20.7167 (2)
24.1982 (2)
100.1638 (4)
103.0992 (4)
94.0864 (3)
5309.31 (8)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
3
˚
V (A )
4159.9 (3)
8
Z
T (K)
173
1.194
0.519
1804
173
1.265
0.619
2124
173
1.408
0.978
1824
Dcalc (g cmꢀ3
)
l (mmꢀ1
F(000)
)
h Range (ꢁ)
Index ranges (h, k, l)
1.21–25.36
18, 20, 22
74051
17380/0.036
14563
17380/0/984
0.0307/0.0728
0.0409/0.0763
1.032
1.46–25.36
13, 24, 29
55808
18623/0.032
15639
18623/0/1151
0.0339/0.0795
0.0447/0.0847
1.030
1.30–23.25
9, 17, 34
13426
2868/0.075
1937
2868/0/225
0.0453/0.0800
0.0882/0.0924
1.025
Number of reflections collected
Number of independent reflections/Rint
Number of observed reflections [I > 2r(I)]
Number of data/restraints/parameters
R1/wR2 [I > 2r(I)]a
R1/wR2 (all data)a
Goodness-of-fit (GOF) (on F2)a
ꢀ3
˚
Largest difference in peak and hole (e A
)
+0.65 and ꢀ0.48
+0.68 and ꢀ0.88
1=2
+0.60 and ꢀ0.68
P
P
P
P
P
R1 ¼ ðkF oj ꢀ jF ckÞ= jF oj; wR2 ¼ f ½wðF 2o ꢀ F c2Þ ꢁ= ½wðF o2Þ ꢁg1=2; GOF ¼ f ½wðF o2 ꢀ F 2cÞ ꢁ=ðn ꢀ pÞg
.
2
2
2
a
P
2
were carried out by minimizing
wðF 2o ꢀ F 2cÞ with the
also thank Degussa for a generous gift of palladium(II)
acetate.
SHELXL-97 weighting scheme and stopped at shift/err
<0.003. The final residual electron density maps showed
no remarkable features. Neutral atom scattering factors
for all atoms and anomalous dispersion corrections for
the non-hydrogen atoms were taken from International
Tables for Crystallography. All calculations were per-
formed on an Intel Pentium 4 PC, with the WINGX system,
including the programs DIAMOND, PLATON, SHELXL-97, and
SIR-92 [30]. Specials: 1a Æ (CH2Cl2): a second solvent mole-
cule could not be resolved and modeled without a doubt.
This problem was cured be using the PLATON ‘‘calc squeeze’’
procedure. Compound 7b Æ 3(CH2Cl2): A disorder over two
positions observed for each of the three independent sol-
vent molecules CH2Cl2 [0.68(1)/0.32(1), 0.61(2)/0.39(2),
and 0.68(3)/0.32(3)] could be resolved and modeled clearly.
The asymmetric unit contains two crystallographic inde-
pendent molecules A and B of the target compound 7b.
Appendix A. Supplementary material
CCDC 638462, 638461 and 638460 contain the supple-
mentary crystallographic data (excluding structure factors)
for [1a Æ (CH2Cl2)], [7b Æ 3(CH2Cl2)] and 11. These data can
be obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit@
ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at doi:10.
1016/j.jorganchem.2007.03.020.
References
[1] (a) A.J. Cheney, B.L. Shaw, J. Chem. Soc., Dalton Trans. (1972) 754;
(b) B.L. Shaw, New J. Chem. 22 (1998) 77;
(c) B.L. Shaw, S.D. Perera, E.A. Staley, Chem. Commun. (1998) 136.
[2] G.J. Gainsford, R. Mason, J. Organomet. Chem. 80 (1974) 395.
[3] (a) E.C. Alyea, S.A. Dias, G. Ferguson, P.J. Roberts, J. Chem. Soc.,
Dalton Trans. (1979) 948;
(b) E.C. Alyea, G. Ferguson, J. Malito, B.L. Ruhl, Organometallics
8 (1989) 1188.
[4] T. Mitsudo, W. Fischetti, R.F. Heck, J. Org. Chem. 49 (1984) 640.
Acknowledgments
We are grateful to Dr. Rian D. Dewhurst for sugges-
tions and fruitful discussions. This work was generously
supported by NanoCat, an International Graduate Pro-
gram within the Elitenetzwerk Bayern (doctoral fellowship
for A.D.T.). G.D.F. gratefully acknowledges the financial
support of the Alexander von Humboldt Foundation. We
¨
[5] W.A. Herrmann, K. Ofele, D. von Preysing, S.K. Schneider, J.
Organomet. Chem. 687 (2003) 229.

A.D. Tanase et al. / Journal of Organometallic Chemistry 692 (2007) 3316–3327
3327
¨
[6] (a) W.A. Herrmann, C. Brossmer, K. Ofele, C.-P. Reisinger, T.
[16] S. Caddick, W. Kofie, Tetrahedron Lett. 43 (2002) 9347.
Priermeier, M. Beller, H. Fischer, Angew. Chem. 107 (1995) 1989;
Angew. Chem., Int. Ed. Engl. 34 (1995) 1844;
[17] C.-P. Reisinger, Ph.D. Thesis, Technische Universita¨t Munchen,
¨
ISBN 3-933083-00-1, 1997.
(b) W.A. Herrmann, C. Brossmer, C.-P. Reisinger, T.H. Riermeier,
[18] G.D. Frey, W.A. Herrmann, J. Organomet. Chem. 690 (2005)
5876.
¨
K. Ofele, M. Beller, Chem. Eur. J. 3 (1997) 1357;
(c) W.A. Herrmann, V.P.W. Bo¨hm, J. Organomet. Chem. 572 (1999)
141;
[19] G.D. Frey, J. Schutz, E. Herdtweck, W.A. Herrmann, Organomet-
¨
allics 24 (2005) 4416.
(d) V.P.W. Bo¨hm, W.A. Herrmann, Chem. Eur. J. 6 (2000) 1017;
[20] G.D. Frey, Phosphapalladacyclen mit N-heterocyclischen Carbenen:
¨
(e) M. Beller, H. Fischer, W.A. Herrmann, K. Ofele, C. Brossmer,
Katalysatoren fur die Heck-Olefinierung, first ed., Verlag Dr. Hut,
¨
Angew. Chem. 107 (1995) 1992;
Munchen, 2005.
¨
Angew. Chem., Int. Ed. Engl. 34 (1995) 1848.
[7] M. Ohff, A. Ohff, M.E. van der Boom, D. Milstein, J. Am. Chem.
Soc. 119 (1997) 11687.
[21] D.A. Albisson, R.B. Bedford, S.E. Lawrence, P.N. Scully, Chem.
Commun. (1998) 2095.
[22] G.D. Frey, Ph.D. Thesis, Technische Universita¨t Munchen, ISBN 3-
¨
[8] B.L. Shaw, S.D. Perera, E.A. Staley, Chem. Commun. (1998) 1361.
[9] G.D. Frey, C.-P. Reisinger, E. Herdtweck, W.A. Herrmann, J.
Organomet. Chem. 690 (2005) 3193.
89963-186-2, 2005.
[23] R.B. Bedford, M. Betham, M.E. Blake, R.M. Frost, P.N. Horton,
´
´
M.B. Hursthouse, R.-M. Lopez-Nicolas, Dalton Trans. 16 (2005)
¨
[10] (a) K. Ofele, W.A. Herrmann, D. Mihalios, M. Elison, E. Herdtweck,
2774.
W. Scherer, J. Mink, J. Organomet. Chem. 459 (1993) 177;
[24] G.D. Frey, J. Schutz, W.A. Herrmann, J. Organomet. Chem. 691
¨
¨
(b) W.A. Herrmann, K. Ofele, M. Elison, F.E. Kuhn, P.W. Roesky,
¨
(2006) 2403.
J. Organomet. Chem. 480 (1994) C7.
[11] (a) T. Weskamp, F.J. Kohl, W. Hieringer, D. Gleich, W.A. Herrmann,
Angew. Chem. 111 (1999) 2573;
[25] W.A. Herrmann, M. Elison, J. Fischer, C. Ko¨cher, G.R.J. Artus,
Angew. Chem. 107 (1995) 2602;
Angew. Chem., Int. Ed. Engl. 34 (1995) 2371.
Angew. Chem., Int. Ed. 38 (1999) 2416;
[26] M. Muhlhofer, T. Strassner, E. Herdtweck, W.A. Herrmann, J.
¨
(b) W.A. Herrmann, T. Weskamp, V.P.W. Bo¨hm, Adv. Organomet.
Chem. 48 (2001) 1;
Organomet. Chem. 660 (2002) 121.
[27] R.B. Bedford, M. Betham, S.J. Coles, P.H. Horton, M. Lopez-Saez,
´
´
(c) W.A. Herrmann, Angew. Chem. 14 (2002) 1343;
Angew. Chem., Int. Ed. 41 (2002) 1290;
(d) M. Bortenschlanger, J. Schutz, D. von Preysing, O. Nuyken,
¨
Polyhedron 25 (2006) 1003.
[28] W.A. Herrmann, V.P.W. Bo¨hm, C.-P. Reisinger, J. Organomet.
Chem. 576 (1999) 23.
W.A. Herrmann, R. Weberskirch, J. Organomet. Chem. 690 (2005)
6233.
[12] (a) E. Peris, R.H. Crabtree, Coord. Chem. Rev. 248 (2004) 2239;
(b) C.M. Crudden, D.P. Allen, Coord. Chem. Rev. 248 (2004) 2247;
(c) I. Dragutan, V. Dragutan, L. Delaude, A. Demonceau, Arkivoc
10 (2005) 206;
[29] A.J. Arduengo III, H. Bock, H. Chen, M. Denk, D.A. Dixon, J.C.
Green, W.A. Herrmann, N.L. Jones, M. Wagner, R. West, J. Am.
Chem. Soc. 116 (1994) 6641.
[30] (a) Data Collection Software for NONIUS j-CCD devices, Delft, The
Netherlands, 2001;
(b) Z. Otwinowski, W. Minor, Meth. Enzymol. 276 (1997) 307ff;
(c) A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M.C.
Burla, G. Polidori, M. Camalli, SIR-92, J. Appl. Crystallogr. 27 (1994)
435;
(d) J.C. Garrison, W.J. Youngs, Chem. Rev. 105 (2005) 3978;
(e) F.E. Hahn, Angew. Chem. 118 (2006) 1374;
Angew. Chem., Int. Ed. 45 (2006) 1348.
[13] A.M. Magill, K.J. Cavell, B.F. Yales, J. Am. Chem. Soc. 126 (2004)
8717.
[14] (a) J. Schwarz, V.P.W. Bo¨hm, M.G. Gardiner, M. Grosche, W.A.
Herrmann, W. Hieringer, G. Raudaschl-Sieber, Chem. Eur. J. 6
(2000) 1773;
(d) A.J.C. Wilson (Ed.), International Tables for Crystallography,
vol. C, Kluwer Academic Publishers, Dordrecht, The Netherlands,
1992, Tables 6.1.1.4, 4.2.6.8, and 4.2.4.2;
(e) G.M. Sheldrick, SHELXL-97, Universita¨t Go¨ttingen, Go¨ttingen,
Germany, 1998;
(b) L. Xu, W. Chen, J. Xiao, Organometallics 19 (2000) 1123;
(c) T. Weskamp, V.P.W. Bo¨hm, W.A. Herrmann, J. Organomet.
Chem. 585 (1999) 348;
(f) A.L. Spek, PLATON: A Multipurpose Crystallographic Tool,
Utrecht University, Utrecht, The Netherlands, 2001;
(g) L.J. Farrugia, WINGX, Version 1.70.01 January 2005, J. Appl.
Crystallogr. 32 (1999) 837;
(h) K. Brandenburg, DIAMOND, Version 3.1d, Crystal Impact GbR,
Bonn, Germany, 2006.
(d) M.L. Trudell, C. Zhang, Tetrahedron Lett. 41 (2000) 59;
(e) T. Scherg, S.K. Schneider, G.D. Frey, J. Schwarz, E. Herdtweck,
W.A. Herrmann, Synlett (2006) 2894, and references cited therein.
[15] S.R. Stauffer, S. Lee, J.P. Stambuli, S.I. Hauck, J.F. Hartwig, Org.
Lett. 2 (2000) 1423.
[31] D. Baskakov, W.A. Herrmann, E. Herdtweck, S.D. Hoffmann,
Organometallics 26 (2007) 626.