Mononuclear palladacycles of N,N′-diaryl-2-iminoisoindolines

Article abstract of DOI:10.1016/j.jorganchem.2008.12.055

Reaction of acetato-bridged dinuclear palladacycles, [Pd(iminoisoindoline)(μ-OAc)]₂, with stoichiometric amounts of PR₃ (where R = Ph or Cy) resulted in formation of the corresponding mononuclear phosphine-ligated, six-membered palla

Full text of DOI:10.1016/j.jorganchem.2008.12.055

Journal of Organometallic Chemistry 694 (2009) 1542–1548
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Mononuclear palladacycles of N,N0-diaryl-2-iminoisoindolines
Jackson M. Chitanda a, J. Wilson Quail b, Stephen R. Foley a,
*
a Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
b Saskatchewan Structural Sciences Centre, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 31 October 2008
Received in revised form 23 December 2008
Accepted 25 December 2008
Available online 3 January 2009
Reaction of acetato-bridged dinuclear palladacycles, [Pd(iminoisoindoline)(l-OAc)]2, with stoichiometric
amounts of PR3 (where R = Ph or Cy) resulted in formation of the corresponding mononuclear phosphine-
ligated, six-membered palladacycles with the general formula [Pd(iminoisoindoline)(OAc)PR3]. The anal-
ogous chloride complexes were synthesized by reaction of [Pd(iminoisoindoline)(l-OAc)]2 with LiCl in
acetone followed by addition of phosphine to afford the monomeric derivatives [Pd(iminoisoindo-
line)(Cl)PR3]. Representative crystal structures of both types of mononuclear palladacycles confirmed
the mononuclear nature of the complexes and showed a trans-arrangement of the phosphine ligand to
the heterocyclic imine-nitrogen of the palladacycles.
Keywords:
Palladacycle
Iminoisoindoline
Palladium chemistry
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
complexes with the general formula [Pd(iminoisoindoline)(
l-
OAc)]2 (Scheme 1) [4].
Isoindoline derivatives have found widespread applications in
the pharmaceutical, herbicidal and dye industries. For example
pazinaclone, staurosporine, and indoprofen all possess an isoindo-
line substructure [1]. We are interested in one particular family of
isoindolines, specifically N,N’-diaryl-2-iminoisoindolines for appli-
cations as ligands in group 10 coordination chemistry. The specific
interest in diaryliminoisoindolines lies in their extreme ease of
synthesis, the ease in which they can be sterically and electroni-
cally tuned and their potential ability to form metallacycles. De-
spite their ease of synthesis, iminoisoindolines remain relatively
unexplored as ligands. While the original synthesis for diphenyli-
minoisoindoline dates back to 1910 [2], few reports exist concern-
ing N,N0-diaryl-2-iminoisoindolines indicating few applications
have been found for this isoindoline subclass [1,3]. N,N0-Diaryl-2-
iminoisoindolines are easily synthesized by reaction of phthalalde-
hyde with two equivalents of an aryl amine in ether as solvent
(Scheme 1). The resulting iminoisoindoline usually precipitates
from solution as an analytically pure solid, allowing for easy isola-
tion [1,4].
Palladacycles represent an increasingly important class of orga-
nometallic compounds, where their influence is especially domi-
nant in the field of coupling reactions for organic transformations
[6,7]. Many palladium-mediated coupling reactions are thought
to involve palladacyclic intermediates [8] and several palladacycles
are also reported to be biologically active compounds for cancer
therapy [9]. Herein we report the synthesis and characterization
of mononuclear iminoisoindoline-based six-membered palladacy-
cles with the general formula [Pd(iminoisoindoline)(OAc)(PR3)]
and [Pd(iminoisoindoline)(Cl)PR3].
2. Results and discussion
2.1. Synthesis and characterization of
[Pd(iminoisoindoline)(OAc)(PR3)] complexes
We previously described the formation of six-membered, aceta-
to-bridged dinuclear palladacycles 1–4 of the general formula
[Pd(iminoisoindoline)(l-OAc)]2 from the reaction of the corre-
We have recently shown that the reaction proceeds through a
sponding iminoisoindoline with Pd(OAc)2 [4]. The solid state struc-
tures of these complexes show that they adopt a characteristic
closed book conformation where the two iminoisoindoline ligands
stacked on top of the other in an anti configuration. In an extension
of our previously reported work, we describe here the synthesis
and characterization of a series of mononuclear phosphine-ligated,
six-membered palladacycles from complexes 1–4.
double condensation reaction to form a
c-diimine which then
undergoes intramolecular cyclization to form the corresponding
iminoisoindoline [5]. para-Substituted N,N’-diaryl-2-iminoisoindo-
lines readily react with Pd(OAc)2 at room temperature resulting
in formation of six-membered [C,N] dinuclear cyclopalladated
Palladacycles 5–10, of the general formula [Pd(imino-
isoindoline)(OAc)(PR3)], (where R = Ph or Cy), were obtained by
* Corresponding author. Tel.: +1 306 966 2960; fax: +1 306 966 4730.
E-mail address: stephen.foley@usask.ca (S.R. Foley).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.12.055

J.M. Chitanda et al. / Journal of Organometallic Chemistry 694 (2009) 1542–1548
1543
elemental analysis, mass spectrometry and NMR spectroscopy. A
characteristic indication of the formation of mononuclear species
is the observed 1H NMR resonance for the CH2 protons of the
iminoisoindoline ring. In dinuclear complexes 1–4, the methylene
protons are diastereotopic resulting in formation of two doublets
each integrating for one proton at ꢀ4.6 and ꢀ3.5 ppm. After reac-
tion with phosphine, the 1H NMR spectra show the disappearance
of the two doublets coincident with the appearance of a new sin-
glet at ꢀ5 ppm integrating for two protons indicating the methy-
lene protons are now chemically equivalent and the new
complexes have an average Cs symmetry in solution. The free imi-
noisoindoline ligands also show a singlet which is ꢀ0.1 ppm up-
field relative to that of phosphine-ligated palladacycles [4,5]. The
31P NMR spectra of these complexes show a singlet at ꢀ33 ppm
consistent with only one isomer being present in solution. The
mass spectra of all complexes show a strong signal which was
assigned to their respective molecular cation [MꢁOAc]+.
R
NH2
H+
N
2 eq
+
N
R
ether
R
O
O
R
Pd(OAc)2
O
N
CH2Cl2
Pd
N
Me
O
R
O R
Me
Pd
N
O
N
2.2. Synthesis and characterization of [Pd(iminoisoindoline)(Cl)(PR3)]
complexes
R
Scheme 1. Synthesis of iminoisoindoline ligands and corresponding acetato-
The acetato-bridged dinuclear palladacycles 1 and 4 were trea-
ted with LiCl in acetone at room temperature resulting in forma-
tion of a yellow precipitate which was presumably the chloride-
bridged analogue of 1 and 4. The products were not characterized
but used as is for the subsequent steps. Addition of LiCl is a general
route for the conversion of acetate-bridged dinuclear palladacycles
to their chloro-bridged analogues [6]. The resulting yellow powder
was isolated and suspended in dichloromethane. Palladacycles
bridged dinuclear palladacycles.
the reaction of acetato-bridged dinuclear palladacycles 1–4 with
stoichiometric amounts of phosphine in acetone at room tempera-
ture (scheme 2). Thus, treatment of dinuclear complexes 1–3 with
two equivalents of PPh3 afforded the corresponding mononuclear
phosphine-ligated complexes 5, 7 and 8 in good yield as yellow sol-
ids. Analogous treatment of complexes 1, 3 and 4 with PCy3 also
afforded the corresponding mononuclear tricyclohexylphosphine-
ligated complexes 6, 9 and 10 (Scheme 2).
The mononuclear palladacycles were obtained in good to
excellent yields (60–94%) and were fully characterized by
R
N
OAc
N
Pd
PR'3
PR'3
acetone
R
R
R = H and R' = Ph(5) or Cy(6)
R = Me and R' = Ph(7)
R = iPr and R' = Ph(8) or Cy(9)
R = COMe and R' = Cy(10)
N
N
OAc
Pd
i) LiCl
ii) PR'3
R
2
R
CH2Cl2
N
N
R = H(1), Me(2)
iPr(3), COMe(4)
Cl
Pd
PR'3
Fig. 1. ORTEP plot of 5 at the 50% probability level. The hydrogen atoms have been
omitted for clarity. Selected bond lengths [Å] and angles [°]: Pd(1)–C(10) = 1.998(3),
Pd(1)–N(2) = 2.086(2), Pd(1)–O(1) = 2.092(2), Pd(1)–P(1) = 2.2739(8), C(10)–Pd(1)–
R
R = H and R' = Ph(11) or Cy(12)
R = COMe and R' = Ph(13) or Cy(14)
N(2) = 87.23(10),
C(10)–Pd(1)–O(1) = 174.97(10),
N(2)–Pd(1)–O(1) = 90.55(9),
C(10)–Pd(1)–P(1) = 93.83(8),
87.74(6).
N(2)–Pd(1)–P(1) = 171.92(7), O(1)–Pd(1)–P(1) =
Scheme 2. Synthesis of mononuclear iminoisoindoline-based palladacycles.

1544
J.M. Chitanda et al. / Journal of Organometallic Chemistry 694 (2009) 1542–1548
Fig. 3. ORTEP plot of 12 at the 50% probability level. The hydrogen atoms have been
omitted for clarity. Selected bond lengths [Å] and angles [°]: Pd(1)–C(10) = 1.995(3),
Pd(1)–N(2) = 2.130(3), Pd(1)–Cl(1) = 2.4077(9), Pd(1)–P(1) = 2.2901(8), C(10)–
Fig. 2. ORTEP plot of 10 at the 30% probability level. The hydrogen atoms have been
omitted for clarity. Symmetry transformations used to generate equivalent atoms:
(i) y, x, ꢁz + 2. Selected bond lengths [Å] and angles [°]: Pd(1)–C(10) = 1.987(3),
Pd(1)–N(2) = 2.138(2), Pd(1)–O(3) = 2.1142(19), Pd(1)–P(1) = 2.2767(7), C(10)–
Pd(1)–N(2) = 83.42(9), C(10)–Pd(1)–O(3) = 174.58(9), N(2)–Pd(1)–O(3) = 91.30(8),
Pd(1)–N(2) = 84.26(12),
C(10)–Pd(1)–Cl(1) = 174.30(9),
N(2)–Pd(1)–Cl(1) =
91.17(8), C(10)–Pd(1)–P(1) = 94.38(9), N(2)–Pd(1)–P(1) = 166.64(8), Cl(1)–Pd(1)–
P(1) = 90.85(3).
C(10)–Pd(1)–P(1) = 91.80(7),
93.15(5).
N(2)–Pd(1)–P(1) = 167.71(6),
O(3)–Pd(1)–P(1) =
captions are selected bond distances and angles. Palladacycles 10
and 15 co-crystallized with a molecule of dichloromethane. Table
1 shows selected crystal data and refinement parameters for the
structures. In all four palladacyclic compounds, the crystal struc-
tures revealed mononuclear species with a slightly distorted
square-planar coordination geometry around the palladium atom.
The environment around each palladium atom consists of a biden-
tate iminoisoindoline [C,N], a terminal chloride or acetate and a
phosphine. The phosphine ligands are always trans to the donor
N atom of the iminoisoindoline ligand. This is consistent with other
reports of mononuclear palladacycles, where the phosphine and
aryl ligands have a well-demonstrated tendency not to be trans
to each other when coordinated to palladium.[10] The six-mem-
bered palladacycles adopt a pseudo-boat conformation which is
illustrated in Fig. 5 using palladacycle 12 as a representative
example. In all four palladacycles the Pd–P bond distances range
from 2.274(1) to 2.290(1) Å. The Pd–Cpalladate bond distances are
all similar at 2.00(1) Å. These values are within the range usually
reported by five- and six-membered palladacycles (1.99–2.01 Å)
[10]. As would be expected, the Pd–N distance for the imine trans
to the PCy3 moiety in complexes 10 and 12 is noticeably shorter
than the corresponding distance in complexes 5 and 13 where
the imine is trans to a PPh3 moiety, consistent with the stronger
trans influence of PCy3. The Pd–N distance for complexes 10 and
12 is 2.138(2) and 2.130(3) Å, respectively, whereas the Pd–N dis-
tance for 5 and 13 is 2.086(2) and 2.110(3) Å, respectively.
11–14, of the general formula [Pd(iminoisoindoline)(Cl)PR3],
(where R = Ph or Cy), were obtained by the reaction of the yellow
suspension with stoichiometric amounts of phosphine at room
temperature (Scheme 2). Over the course of 12 h, the yellow sus-
pension gradually became a clear solution which, after work up,
afforded the desired products. Thus, treatment of dinuclear com-
plexes 1 and 4 with LiCl followed by two equivalents of PPh3 affor-
ded the corresponding mononuclear phosphine-ligated complexes
11 and 13 in good yields (84% and 78%, respectively). Analogous
treatment of complexes 1 and 4 with LiCl and PCy3 also afforded
the corresponding mononuclear tricyclohexylphosphine-ligated
complexes 12 and 14 in 80% and 90% yields, respectively (Scheme
2). The NMR spectra were consistent with those observed for the
mononuclear acetato analogues 5–10. The mass spectra of all com-
plexes show a strong signal which was assigned to their respective
molecular cation [MꢁCl]+.
2.3. Crystal structures of complexes 5, 10, 12 and 13
To further clarify the coordination environment around the me-
tal center, representative molecular structures of 5–14 have been
ascertained by means of X-ray diffraction studies. Single crystals
of complexes 5, 10, 12 and 13 were obtained by slow evaporation
of a concentrated dichloromethane/hexane (1:1) solution. ORTEP
plots are shown in Figs. 1–4, and included in their respective

J.M. Chitanda et al. / Journal of Organometallic Chemistry 694 (2009) 1542–1548
1545
Fig. 4. ORTEP plot of 13 at the 50% probability level. The hydrogen atoms have been omitted for clarity. Selected bond lengths [Å] and angles [°]: Pd(1)–C(10) = 1.992(4),
Pd(1)–N(2) = 2.110(3), Pd(1)–Cl(1) = 2.3990(10), Pd(1)–P(1) = 2.2540(11), C(10)–Pd(1)–N(2) = 85.25(14), C(10)–Pd(1)–Cl(1) = 174.02(11), N(2)–Pd(1)–Cl(1) = 94.47(9), C(10)–
Pd(1)–P(1) = 93.93(11), N(2)–Pd(1)–P(1) = 160.16(9), Cl(1)–Pd(1)–P(1) = 88.35(4).
Table 1
Crystal data and refinement parameters for complexes 5, 10 ꢂ CH2Cl2, 12 and 13 ꢂ CH2Cl2.
5
10 ꢂ CH2Cl2
12
13 ꢂ CH2Cl2
Formula
Formula weight
Color
Crystal size (mm)
Crystal system
Space group
a (Å)
C40H33N2O2PPd
711.05
C45H57Cl2N2O4PPd
898.20
Yellow
C38H48ClN2PPd
705.60
Yellow
0.25 ꢃ 0.20 ꢃ 0.18
Monoclinic
P21/c
11.7619(2)
19.3702(4)
15.9664(3)
90
113.0660(10)
90
4
1.400
173(2)
C43H36Cl3N2O2PPd
856.46
Yellow
0.15 ꢃ 0.15 ꢃ 0.10
Monoclinic
P21/c
17.0313(4)
15.4993(3)
29.3952(8)
90
90.6215(9)
90
4
1.466
173(2)
Pale yellow
0.22 ꢃ 0.12 ꢃ 0.12
Triclinic
0.18 ꢃ 0.11 ꢃ 0.08
Triclinic
ꢀ
ꢀ
P1
P1
10.2458(3)
12.6323(3)
13.8280(3)
83.401(2)
81.0430(10)
66.857(2)
2
9.8823(2)
12.1332(2)
17.9651(3)
88.5070(10)
86.9870(10)
81.5910(10)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
Z
qcalc (Mg mꢁ3
T (K)
)
1.455
173(2)
1.402
173(2)
Collec./Ind. Ref.
Rint
23729/7437
0.0563
49446/14683
0.0731
44459/6834
0.0850
60310/8877
0.0997
F(000)
728
936
1472
3488
h range (°)
Final R1 (I > 2
3.28–27.53
R1 = 0.0411,
wR2 = 0.0810
R1 = 0.0550,
wR2 = 0.0884
2.06–31.99
R1 = 0.0555,
wR2 = 0.1099
R1 = 0.0903,
wR2 = 0.1259
2.52–26.37
R1 = 0.0427,
wR2 = 0.0955
R1 = 0.0595,
wR2 = 0.1064
1.78–27.48
R1 = 0.0529
wR2 = 0.1046
R1 = 0.0970
wR2 = 0.1216
rI)
R1 (all data)
are particularly good precatalysts for carbon–carbon bond forming
reactions. Mononuclear trialkylphosphine-ligated palladacycles
have been shown to be especially effective for Suzuki and Heck
coupling chemistry [10b,11]. Currently in progress are catalytic
studies of these mononuclear complexes in C–C coupling reactions
and this work will be reported at a later date.
3. Conclusion
We have successfully synthesized and characterized a series of
six-membered, mononuclear iminoisoindoline-based palladacycles
as air and moisture stable complexes. Much of the recent activity
in palladacyclic chemistry has been prompted by the fact that they

1546
J.M. Chitanda et al. / Journal of Organometallic Chemistry 694 (2009) 1542–1548
23.69 (CO2CH3). 31P NMR (CDCl3, ppm)
d 34.04. Elemental
Anal. Calc. for C40H33N2O2PPd (CH2Cl2)0.7: C, 63.44; H, 4.50; N,
3.64. Found: C, 63.17; H, 4.40; N, 3.96% (1H NMR analysis of
sample showed presence of 0.6 equiv of CH2Cl2 which was
used as the crystallization solvent). HRMS m/z Calc. for
C40H33N2O2PPd: 710.1314 [M], 651.1181 [MꢁOAc]+. Found
651.1155 [MꢁOAc]+.
4.4. Synthesis of [Pd(N,N0-diphenyl-2-iminoisoindoline)(OAc)PCy3] (6)
Compound 6 was obtained as a yellow powder in 90% yield
from palladacycle 1 (341 mg, 0.380 mmol) and tricyclohexylphos-
phine (224 mg, 0.799 mmol) using procedure A. 1H NMR (CDCl3,
ppm) d 7.47 (m, 2H, Ar), 7.39 (m, 1H, Ar), 7.26 (m, 2H, Ar), 7.18
(m, 3H, Ar), 7.00 (m, 2H, Ar), 6.84 (m, 2H, Ar), 6.15 (d, J = 8.1, 1H,
Ar), 5.08 (s, 2H, –CH2–), 2.01 (m, 3H, PCy3), 1.82 (m, 6H, PCy3),
1.71 (m, 6H, PCy3), 1.63 (m, 3H, PCy3), 1.59 (s, 3H, CO2CH3),
1.42(m, 6H, PCy3), 1.13(m, 9H, PCy3); 13C NMR (CDCl3, ppm): d
176.43 CO2CH3), 157.18 (C@N), 146.63, 141.98, 140.63, 140.56,
139.54, 134.28, 131.16, 130.75, 128.52, 127.17, 126.48, 126.48,
125.36, 124.08, 123.38, 123.35, 122.63, 114.26, 51.49 (–CH2–),
33.28, 33.11, 29.72, 28.14, 28.05, 26.76, 25.71. 31P NMR (CDCl3,
ppm) d 32.96. Elemental Anal. Calc. for C40H51N2O2PPd: C, 65.88;
H, 7.05; N, 3.39. Found: C, 65.58; H, 7.04; N, 3.64%. HRMS m/z Calc.
for C40H51N2O2PPd: 728.2723 [M], 669.2590 [MꢁOAc]+. Found
669.2574 [MꢁOAc]+.
Fig. 5. ORTEP plot illustrating the core geometry of palladacycle 12.
4. Experimental
4.1. General
Unless otherwise stated, all reactions were performed under N2
using standard Schlenk techniques or in a N2-filled drybox. Sol-
vents were dried using a MBraun solvent purification system and
stored under nitrogen. 1H, 31P and 13C {1H} NMR spectra were re-
corded on a Bruker 500 MHz Avance spectrometer. Chemical shifts
for 1H and 13C NMR are reported in ppm in reference to the residual
1H and 13C resonances of CDCl3 (1H: d 7.24; 13C: d 77.23). 31P NMR
chemical shifts are also reported in ppm with respect to 85%
H3PO4, set to zero as an external standard. Coupling constants
are given in Hz. High resolution mass spectra (HRMS) were mea-
sured on an Applied Biosystem QSTARÒ XL MS/MS system (ESI-
QTOF). Elemental analyses were performed on a Perkin–Elmer
4.5. [Pd(N,N0-di(p-methylphenyl)-2-iminoisoindoline)(OAc)PPh3] (7)
Compound 7 was obtained as a yellow powder in 70% yield
from palladacycle 2 (237 mg, 0.249 mmol) and triphenylphos-
phine (144 mg, 0.549 mmol) using procedure A. 1H NMR (CDCl3,
ppm) d 7.49 (m, 8H, Ar), 7.35 (m, 5H, Ar), 7.27 (m, 4H, Ar), 7.13
(d, J = 7.4, 2H, Ar), 7.02 (m, 3H, Ar), 6.82 (d, J = 7.8, 1H, Ar), 6.66
(d, J = 7.0, 1H, Ar), 6.47 (br, s, 1H, Ar), 6.14 (d, J = 7.8, 1H, Ar),
5.12 (s, 2H, –CH2–), 2.32 (s, 3H, C6H4–CH3), 1.57 (s, 3H, C6H3–
CH3), 1.07 (s, 3H, CO2CH3); 13C NMR (CDCl3, ppm): d 176.06
(CO2CH3), 156.17 (C@N), 144.24, 141.65, 136.23, 135.38, 135.29,
135.18, 132.29, 131.64, 131.28, 131.12, 131.07, 129.51, 129.10,
128.65, 128.11, 128.02, 127.82, 127.11, 126.58, 126.12, 125.51,
124.99, 122.45, 114.01, 52.08 (–CH2–), 24.30 (C6H4–CH3), 21.35
2400 CHN elemental analyzer. [Pd(iminoisoindoline)(l-OAc)]2
complexes were synthesized following literature procedures [4].
Tricyclohexylphosphine, triphenylphosphine, aniline, p-acetoani-
line, p-isopropylaniline, p-tertiarybutylaniline were purchased
from the Sigma–Aldrich Chemical Company. Phthalaldehyde was
purchased from Alfa Aesar. All chemicals were used as received.
4.2. General procedure (A) for synthesis of
[Pd(iminoisoindoline)(OAc)(PR3)] complexes 5–10
(C6H3–CH3), 20.21 CO2CH3). 31P NMR (CDCl3, ppm)
d 33.90.
A flask was charged with [Pd(iminoisoindoline)(
l
-OAc)]2, 1–4
Elemental Anal. Calc. for C42H37N2O2PPd: C, 68.25; H, 5.05; N,
3.79. Found: C, 67.89; H, 4.97; N, 3.84%. HRMS m/z Calc. for
C42H37N2O2PPd: 738.1627 [M], 679.1494 [MꢁOAc]+. Found
679.1475 [MꢁOAc]+.
and either triphenylphosphine or tricyclohexylphosphine (stoichi-
ometric amounts) in acetone (30 mL, degassed). The resulting sus-
pension slowly became a clear, colourless solution over the course
of 12 h. The resulting solution was filtered and the filtrate was con-
centrated to circa 2 mL. Hexanes were then added to precipitate
out the desired complex, which was filtered, washed with
3 ꢃ 10 mL of hexanes, and then dried under vacuum. Single crys-
tals of palladacycles 5 and 10 were obtained from slow evaporation
of a dichloromethane/hexane (1:1) solution.
4.6. [Pd(N,N0-di(p-isopropylphenyl)-2-iminoisoindoline)(OAc)PPh3]
(8)
Compound 8 was obtained as a yellow powder in 60% yield
from palladacycle 3 (255 mg, 0.239 mmol) and triphenylphosphine
(144 mg, 0.549 mmol) using procedure A. 1H NMR (CDCl3, ppm) d
7.52 (m, 6H, Ar), 7.45 (d, J = 7.6, 1H, Ar), 7.35 (m, 5H, Ar), 7.25 (m,
5H, Ar), 7.18 (d, J = 8.2, 2H, Ar), 7.09 (d, J = 8.2, 2H, Ar), 6.96 (m, 1H,
Ar), 6.92 (d, J = 8.4, 1H, Ar), 6.77 (m, 2H, Ar), 5.99 (d, J = 8.2, 1H, Ar),
5.13 (s, 2H, –CH2–), 2.88 (sept., J = 6.9, 1H, –CH(CH3)2), 2.10 (sept.,
J = 6.9, 1H, –CH(CH3)2), 1.22 (d, J = 6.9, 6H, –CH(CH3)2), 1.05 (s, 3H,
CO2CH3), 0.61 (d, J = 6.9, 6H, –CH(CH3)2); 13C NMR (CDCl3, ppm): d
176.01 (–CO2CH3), 155.82 (C@N), 146.25, 144.55, 143.03, 141.53,
136.41, 135.53, 135.44, 135.36, 131.87, 131.50, 131.13, 131.01,
130.03, 128.65, 128.40, 128.12, 128.04, 127.76, 127.14, 126.74,
126.30, 122.61, 122.37, 114.45, 52.32 (–CH2–), 33.91 (–CH(CH3)2),
33.11 (–CH(CH3)2), 24.33 (–CH(CH3)2), 23.98 (–CO2CH3), 23.54
(–CH(CH3)2). 31P NMR (CDCl3, ppm) d 34.20. Elemental Anal. Calc.
for C46H45N2O2PPd: C, 69.47; H, 5.70; N, 3.52. Found: C, 69.30; H,
4.3. Synthesis of [Pd(N,N0-diphenyl-2-iminoisoindoline)(OAc)PPh3] (5)
Compound 5 was obtained as a yellow powder in 94% yield
from palladacycle 1 (203 mg, 0.226 mmol) and triphenylphosphine
(130 mg, 0.497 mmol) using procedure A. 1H NMR (CDCl3, ppm) d
7.51 (m, 7H, Ar), 7.39 (m, 1H, Ar), 7.33 (m, 3H, Ar), 7.27 (m, 10H,
Ar), 7.22 (m, 1H, Ar), 7.00 (m, 2H, Ar), 6.87 (m, 1H, Ar), 6.75 (m,
1H, Ar), 6.23 (m, 1H, Ar), 6.03 (d, J = 8.0, 1H, Ar), 5.16 (s, 2H,
–CH2–), 1.04 (s, 3H, CO2CH3); 13C NMR (CDCl3, ppm): d 175.36
(CO2CH3), 155.94 (C@N), 146.27, 141.24, 140.21, 140.10, 137.68,
134.71, 134.62, 131.65, 131.58, 130.89, 130.82, 130.44, 130.15,
129.61, 128.78, 128.24, 128.15, 127.92, 127.60, 127.52, 127.33,
126.30, 125.30, 124.05, 122.66, 122.19, 124.33, 51.63 (–CH2–),

J.M. Chitanda et al. / Journal of Organometallic Chemistry 694 (2009) 1542–1548
1547
5.48; N, 3.70%. HRMS m/z Calc. for C46H45N2O2PPd: 794.2253 [M],
4.10. Synthesis of [Pd(N,N0-diphenyl-2-iminoisoindoline)(Cl)PPh3]
(11)
735.2120 [MꢁOAc]+. Found 735.2088 [MꢁOAc]+.
4.7. [Pd(N,N0-di(p-isopropylphenyl)-2-iminoisoindoline)(OAc)PCy3]
(9)
(84.0%, yellow powder). 1H NMR (CDCl3, ppm) d 7.56 (m, 7H,
Ar), 7.48 (m, 3H, Ar), 7.41 (m, 1H,Ar), 7.29 (m, 6H, Ar), 7.22 (m,
5H, Ar), 7.03 (m, 1H, Ar), 6.80 (m, 3H, Ar) 6.15 (m, 2H, Ar), 5.15
(s, 2H, –CH2–); 13C NMR (CDCl3, ppm): d 157.65 (AC@NA),
147.03, 141.98, 141.77, 141.67, 137.32, 136.86, 135.30, 135.21,
132.28, 131.90, 131.33, 131.00, 130.00, 128.22, 128.08, 128.00,
127.71, 127.16, 125.99, 123.98, 123.85, 122.62, 51.46 (–CH2–).
Compound 9 was obtained as a yellow powder in 82% yield
from palladacycle 3 (250 mg, 0.235 mmol) and tricyclohexylphos-
phine (139 mg, 0.496 mmol) using procedure A. 1H NMR (CDCl3,
ppm) d 7.44 (d, J = 7.5, 1H, Ar), 7.36 (m, 2H, Ar), 7.09 (d, J = 8.3,
2H, Ar), 7.05 (d, J = 8.3, 2H, Ar) 6.98 (m, 1H, Ar), 6.83 (d, J = 8.2,
Ar), 6.77 (d, J = 8.2, 1H, Ar), 6.14 (d, J = 8.1, 1H, Ar), 5.03 (s, 2H,
–CH2–), 2.91 (sept., J = 6.9, 1H, –CH(CH3)2), 2.77 (sept., J = 6.9, 1H,
–CH(CH3)2), 2.01 (m, 3H, PCy3), 1.84 (m, 7H, PCy3), 1.69 (m,
7H, PCy3), 1.61 (m, 4H, PCy3), 1.57 (s, 3H, –CO2CH3), 1.38 (m, 6H,
PCy3), 1.22 (m, 12H, –CH(CH3)2) 1.17 (m, 4H, PCy3), 1.06 (m, 7H,
PCy3); 13C NMR (CDCl3, ppm): d 176.33 (–CO2CH3), 156.92 (C@N),
145.69, 144.34, 143.05, 141.86, 138.76, 138.69, 137.48, 134.30,
130.92, 130.88, 127.71, 127.15, 126.27, 122.51, 122.03, 113.94,
100.17, 51.53 (–CH2–), 34.03, 33.90, 33.31, 33.15, 30.20, 29.69,
28.11, 28.02, 26.71, 26.56, 25.62, 24.45, 24.36. 31P NMR (CDCl3,
ppm) d 33.16. HRMS m/z Calc. for C46H63N2O2PPd: 812.3662 [M],
753.3529 [MꢁOAc]+. Found 753.3557 [MꢁOAc]+.
31P NMR (CDCl3, ppm)
d 34.81. Elemental Anal. Calc. for
C38H30ClN2PPd: C, 66.39; H, 4.40; N, 4.07. Found: C, 66.56; H,
4.42; N, 3.93%. HRMS m/z Calc. for C38H30ClN2PPd: 686.0870 [M],
651.1181 [MꢁCl]+. Found 651.1194 [MꢁCl]+.
4.11. Synthesis of [Pd(N,N0-diphenyl-2-iminoisoindoline)(Cl)PCy3]
(12)
(80.0%, yellow powder). 1H NMR (CDCl3, ppm) d 7.49 (m, 3H,
Ar), 7.40 (m, 1H, Ar), 7.24 (m, 3H, Ar), 7.16 (m, 1H, Ar), 7.03 (m,
2H, Ar), 6.92 (m, 1H, Ar), 6.85 (d, J = 7.8, 1H, Ar), 6.31 (d, J = 8.1,
1H, Ar), 5.11 (s, 2H, –CH2–), 2.21 (m, 3H, PCy3), 1.84 (m, 6H,
PCy3), 1.69 (m, 6H, PCy3), 1.56 (m, 9H, PCy3), 1.19 (m, 3H, PCy3),
1.05 (m, 6H, PCy3); 13C NMR (CDCl3, ppm): d 159.00 (AC@NA),
147.27, 142.43, 139.87, 139.81, 139.64, 138.66, 131.27, 130.75,
130.73, 128.21, 128.02, 127.27, 127.15, 125.56, 124.59, 124.56,
124.11, 122.72, 114.16, 50.84 (–CH2–), 34.54 (PCy3), 34.36 (PCy3),
30.17 (PCy3), 28.04 (PCy3), 27.96 (PCy3), 26.74 (PCy3). 31P NMR
(CDCl3, ppm) d 34.99. Elemental Anal. Calc. for C38H48ClN2PPd: C,
64.68; H, 6.86; N, 3.97. Found: C, 64.53; H, 6.49; N, 3.97%. HRMS
m/z Calc. for C38H48ClN2PPd: 704.2 [M], 669.3 [MꢁCl]+. Found
669.3 [MꢁCl]+.
4.8. [Pd(N,N0-di(p-acetophenyl)-2-iminoisoindoline)(OAc)PCy3] (10)
Compound 10 was obtained as a yellow powder in 78% yield
from palladacycle 4 (228 mg, 0.214 mmol) and tricyclohexylphos-
phine (126 mg, 0.449 mmol) using procedure A. 1H NMR (CDCl3,
ppm) d 8.15 (m, 1H, Ar), 7.90 (d, J = 8.1, 2H, Ar), 7.63 (d, J = 8.2,
1H, Ar), 7.51 (d, J = 7.4, 1H, Ar), 7.45 (m, 1H, Ar), 7.27 (d, J = 8.1,
2H, Ar), 7.05 (m, 1H, Ar), 6.92 (d, J = 8.4, 1H, Ar), 6.31 (d, J = 8.1,
2H, Ar), 5.16 (s, 2H, –CH2–), 2.60 (s, 3H, AC(@O)CH3), 2.53 (s, 3H,
AC(@O)CH3), 2.01 (m, 3H, PCy3), 1.83 (m, 6H, PCy3), 1.71 (m, 6H,
PCy3), 1.62 (m, 3H, PCy3), 1.53 (s, 3H, –CO2CH3), 1.48 (m, 6H,
PCy3), 1.15 (m, 3H, PCy3), 1.04 (m, 6H, PCy3); 13C NMR (CDCl3,
4.12. Synthesis of [Pd(N,N0-di(p-acetophenyl)-2-
iminoisoindoline)(Cl)PPh3] (13)
ppm):
d
197.90 (AC(@O)CH3), 197.78 (AC(@O)CH3), 176.47
(78.0%, yellow powder). 1H NMR (CDCl3, ppm) d 7.95 (d, J = 8.6,
2H, Ar), 7.56 (m, 9H, Ar), 7.53 (m, 1H, Ar), 7.42 (m, 2H, Ar), 7.31 (m,
3H, Ar), 7.23 (m, 6H, Ar), 7.07 (m, 1H, Ar), 6.91 (d, J = 8.7, 1H, Ar),
6.31 (d, J = 8.7, 1H, Ar), 5.21 (s, 2H, –CH2–), 2.60 (s, 3H,
AC(@O)CH3), 2.01 (s, 3H, AC(@O)CH3); 13C NMR (CDCl3, ppm): d
197.83 (AC(@O)CH3), 197.13 (AC(@O)CH3), 157.55 (AC@N),
150.81, 143.16, 143.05, 141.97, 141.05, 135.19, 135.10, 134.91,
132.21, 131.56, 131.16, 130.43, 130.13, 128.8, 128.49, 128.32,
128.23, 127.66, 127.14, 124.55, 122.96, 113.77, 51.91 (–CH2–),
26.87 (AC(@O)CH3), 26.10 (AC(@O)CH3). 31P NMR (CDCl3, ppm) d
35.70. Elemental Anal. Calcd. for C42H34ClN2O2PPd ꢂ (CH2Cl2): C,
60.30; H, 4.24; N, 3.27. Found: C, 60.57; H, 3.92; N, 3.45%. HRMS
m/z Calc. for C42H34ClN2O2PPd: 770.1081 [M], 735.1393 [MꢁCl]+
found 735.1400 [MꢁCl]+.
(–CO2CH3), 157.03 (AC@NA), 150.99, 143.09, 141.86, 141.63,
141.56, 134.86, 134.17, 132.44, 132.42, 132.00, 130.05, 130.00,
128.25, 127.21, 126.43, 124.90, 122.91, 114.04, 52.21, 33.55,
33.38, 29.79, 28.13, 28.05, 26.89, 26.87, 26.63, 25.42; 31P NMR
(CDCl3,
ppm)
d
35.16.
Elemental
Anal.
Calc.
for
C44H55N2O4PPd ꢂ (CH2Cl2)0.3: C, 63.43; H, 6.68; N, 3.34. Found: C,
63.47; H, 6.51; N, 3.27% (1H NMR analysis of the sample showed
presence of 0.3 equiv of CH2Cl2 which was used as the crystalliza-
tion solvent). HRMS m/z Calc. for C44H55N2O4PPd: 812.2934 [M],
753.2801 [MꢁOAc]+. Found 753.2754 [MꢁOAc]+.
4.9. General procedure (B) for synthesis of
[Pd(iminoisoindoline)(Cl)PR3] complexes 11-14
A flask was charged with [Pd(iminoisoindoline)(
l
-OAc)]2 and
4.13. Synthesis of [Pd(N,N0-di(p-acetophenyl)-2-
excess (20 equiv) LiCl in acetone and the mixture was stirred for
12 h. The resulting yellow precipitate was isolated, washed with
water then acetone and dried under vacuum. The resulting yellow
powder then suspended in dichloromethane. Palladacycles 11–14
were obtained by the reaction of the yellow suspension with equi-
molar amounts of phosphine (PPh3 or PCy3) at room temperature.
Over the course of 12 h with stirring, the yellow suspension grad-
ually became a clear colourless solution. The resulting solution was
filtered and the filtrate was concentrated to circa 2 mL. Hexanes
were then added to precipitate out the desired complex, which
was filtered, washed with 3 ꢃ 10 mL of hexanes, then dried under
vacuum. Single crystals of palladacycles 12 and 13 were obtained
from slow evaporation of a concentrated dichloromethane/hexane
(1:1) solution.
iminoisoindoline)(Cl)PCy3] (14)
(90.0%, pale yellow powder). 1H NMR (CDCl3, ppm) d 8.17 (s, 1H,
Ar), 7.90 (d, J = 8.4, 2H, Ar), 7.67 (d, J = 8.4, 1H, Ar), 7.54 (m, 4H, Ar),
7.09 (m, 1H, Ar), 6.94 (d, J = 8.4, 1H, Ar), 6.47 (d, J = 8.1, 1H, Ar), 5.19
(s, 2H, –CH2–), 2.59 (s, 3H, AC(@O)CH3), 2.55 (s, 3H, AC(@O)CH3),
2.18 (m, 3H, PCy3), 1.85 (m, 6H, PCy3), 1.69 (m, 6H, PCy3), 1.55
(m, 9H, PCy3), 1.19 (m, 3H, PCy3), 1.05 (m, 6H, PCy3).; 13C NMR
(CDCl3, ppm):
d 197.84 (AC(@O)CH3), 197.53 (AC(@O)CH3),
158.72 (AC@NA), 150.96, 143.26, 142.33, 140.71, 140.65, 138.48,
134.47, 133.64, 132.16, 129.93, 129.22, 128.75, 128.42, 127.23,
127.14, 125.02, 123.02, 113.97, 51.43(–CH2–), 34.78 (PCy3), 34.60
(PCy3), 30.19 (PCy3), 28.05 (PCy3), 27.96 (PCy3), 26.82 (PCy3),
26.74 (AC(@O)CH3), 26.61 (AC(@O)CH3). 31P NMR (CDCl3, ppm) d

1548
J.M. Chitanda et al. / Journal of Organometallic Chemistry 694 (2009) 1542–1548
[4] J.M. Chitanda, D.E. Prokopchuk, J.W. Quail, S.R. Foley, Dalton Trans. (2008)
6023–6029.
[5] J.M. Chitanda, D.E. Prokopchuk, J.W. Quail, S.R. Foley, Organometallics 27
(2008) 2337–2345.
[6] (a) J. Dupont, C.S. Consorti, J. Spencer, Chem. Rev. 105 (2005) 2527–2572;
(b) J. Vicente, I. Saura-Llamas, Comments Inorg. Chem. 28 (2007) 39–72;
(c) R.B. Bedford, C.S.J. Cazin, D. Holder, Coord. Chem. Rev. 248 (2004) 2283–
2321;
37.29. Elemental Anal. Calc. for C42H52ClN2O2PPd: C, 63.88; H, 6.64;
N, 3.55. Found: C, 63.76; H, 6.77; N, 3.54%. HRMS m/z Calc. for
C42H52ClN2O2PPd: 788.2490 [M], 753.2801 [MꢁCl]+ found
735.2799 [MꢁCl]+.
4.14. X-ray structure determinations
(d) V. Farina, Adv. Synth. Catal. 346 (2004) 1553–1582;
(e) I.P. Beletskaya, A.V. Cheprakov, J. Organomet. Chem. 689 (2004) 4055–
4082;
(f) W.A. Herrmann, K. Ofele, D. von Preysing, S.K. Schneider, J. Organomet.
Chem. 687 (2003) 229–248.
Data were collected at ꢁ100 °C on a Nonius Kappa CCD diffrac-
tometer, using the COLLECT program [12]. Cell refinement and data
reductions used the programs DENZO and SCALEPACK [13]. SIR97 [14]
was used to solve the structures and SHELXL97 [15] was used to re-
fine the structures. ORTEP-3 for Windows [16] was used for molecu-
lar graphics and PLATON [17] was used to prepare material for
publication. H atoms were placed in calculated positions with Uiso
constrained to be 1.5 times Ueq of the carrier atom for methyl pro-
tons and 1.2 times Ueq of the carrier atom for all other hydrogen
atoms.
[7] (a) J. Dupont, M. Pfeffer (Eds.), Palladacycles Synthesis Characterization and
Applications, Wiley-VCH, Weinheim, 2008;
(b) J. Tsuji, Palladium Reagents and Catalysts, Wiley, New York, 2004;
(c) A. de Meijere, P.J. Diederich (Eds.), Metal-catalyzed Cross-coupling
Reactions, Wiley-VCH, Weinheim, 2004;
(d) E. Negishi, A. de Mejere, Handbook of Organopalladium Chemistry for
Organic Synthesis, Wiley-VCH, Weinheim, 2002.
[8] (a) G. Dyker (Ed.), Handbook of C–H Transformations, Wiley-VCH, Weinheim,
2005;
(b) L. Wu, J.F. Hartwig, J. Am. Chem. Soc. 127 (2005) 15824–15832;
(c) R.B. Bedford, Chem. Commun. (2003) 1787–1796;
Acknowledgments
(d) J.-H. Chu, C.-C. Chen, M. -J. Wu, Organometallics 27 (2008) 5173–5176;
(e) M. Catellani, E. Motti, N.D. Ca, Acc. Chem. Res. 41 (2008) 1512–1522.
[9] (a) A.C.F. Caires, Anti-Cancer Agents Med. Chem. 7 (2007) 484–491;
(b) C.M.V. Barbosa, C.R. Oliveira, F.D. Nascimento, M.C.M. Smith, D.M. Fausto,
M.A. Soufen, E. Sena, R.C. Araújo, I.L.S. Tersariol, C. Bincoletto, A.C.F. Caires, Eur.
J. Pharmacol. 542 (2006) 37–47.
[10] (a) J. Albert, R. Bosque, J. Granell, R.J. Tavera, Organomet. Chem. 595 (2000) 54;
(b) R.B. Bedford, C.S.J. Cazin, S.J. Coles, T. Gelbrich, P.N. Horton, M.B.
Hursthouse, M.E. Light, Organometallics 22 (2003) 987–999;
(c) A. Fernández, D. Vázquez-García, J.J. Fernández, M. López-Torres, A. Suárez,
C.-J. Samuel, J.M. Vila, Eur. J. Inorg. Chem. (2002) 2389;
(d) R.Y. Mawo, D.M. Johnson, J.L. Wood, I.P. Smoliakova, J. Organomet. Chem.
693 (2008) 33–45;
We gratefully thank the Natural Sciences and Engineering Re-
search Council of Canada (NSERC) for financial support and the
Canadian Government through the Commonwealth Scholarship
fund for J.M.C.’s doctoral fellowship.
Appendix A. Supplementary material
CCDC 707316, 707317, 707318 and 707319 contain the supple-
mentary crystallographic data for 5, 10 ꢂ CH2Cl2, 12 and 13 ꢂ CH2Cl2,
respectively. Supplementary data associated with this article can
be found, in the online version, at doi:10.1016/j.jorganchem.2008.
12.055.
(e) J. Vicente, I. Saura-Llamas, J. Cuadrado, Organometallics 22 (2003) 5513–
5517;
(f) J. Vicente, J. -A. Abad, E. Martnez-Viviente, P.G. Jones, Organometallics 21
(2002) 4454–4467.
[11] R.B. Bedford, C.S.J. Cazin, Chem. Commun. (2001) 1540–1541.
[12] Nonius., COLLECT, Nonius BV, Delft, The Netherlands, 1998.
[13] Z. Otwinowski, W. Minor, in: C.W. Carter, R.M. Sweet (Eds.), Methods in
Enzymology, Macromolecular Crystallography, Part A, vol. 276, Academic
Press, London, 1997, pp. 307–326.
References
[1] I. Takahashi, K. Nishiuchi, R. Miyamoto, M. Hatanaka, H. Uchida, K. Isa, A.
Sakushima, S. Hosoi, Lett. Org. Chem. 2 (2005) 40–43.
[2] J. Thiele, J. Schneider, Justus Liebigs Ann. Chem. 369 (1910) 287–299.
[3] (a) I. Takahashi, R. Miyamoto, K. Nishiuchi, M. Hatanaka, A. Yamano, A.
Sakushima, S. Hosoi, Heterocycles 63 (2004) 1267–1271;
[14] A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo, A. Guagliardi,
A.G.G. Moliterni, G. Polidori, R. Spagna, J. Appl. Cryst. 32 (1999) 115.
[15] G.M. Sheldrick, SHELXL-97, University of Göttingen, Germany, 1997.
[16] L.J. Farrugia, J. Appl. Cryst. 30 (1997) 565.
[17] A.L. Spek, PLATON, University of Utrecht, The Netherlands, 2001.
(b) A.A. Hassan, D. Dopp, G. Henkel, J. Heterocyclic Chem. 35 (1998) 121–128.