The mechanism for palladium catalyzed carbonylation of cinnamyl chloride

Article abstract of DOI:10.1016/j.jorganchem.2004.07.016

In the palladium catalyzed alkoxycarbonylation of cinnamyl chloride two mechanisms play a role. An associative mechanism was observed at low pressure, while an insertion mechanism was observed at high pressure or when an excess of ligand was used. Several putative intermediates of the catalytic alkoxycarbonylation have been synthesized and characterized, such as 5c of which an X-ray crystal structure was obtained.

Full text of DOI:10.1016/j.jorganchem.2004.07.016

Journal of Organometallic Chemistry 689 (2004) 3800–3805
www.elsevier.com/locate/jorganchem
The mechanism for palladium catalyzed carbonylation of
cinnamyl chloride
1
Richard J. van Haaren , Henk Oevering, Paul C.J. Kamer, Kees Goubitz, Jan Fraanje,
*
Piet W.N.M. van Leeuwen , Gino P.F. van Strijdonck
Institute of Molecular Chemistry, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, Netherlands
Received 5 July 2004; accepted 9 July 2004
Available online 27 August 2004
Abstract
In the palladium catalyzed alkoxycarbonylation of cinnamyl chloride two mechanisms play a role. An associative mechanism was
observed at low pressure, while an insertion mechanism was observed at high pressure or when an excess of ligand was used. Several
putative intermediates of the catalytic alkoxycarbonylation have been synthesized and characterized, such as 5c of which an X-ray
crystal structure was obtained.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Cinnamyl chloride; Carboxylation; Palladium catalyzed carbonylation; Acylpalladium complexes; Carbomethoxypalladium complexes
1. Introduction
intermediate, which is in equilibrium with
a
(PR3)2Pd(g1-benzyl)X intermediate. Treatment of such
complexes with CO leads to insertion of CO in Pd-g1-
benzyl bonds [16] forming the acyl complex
(PR3)2Pd(C(O)benzyl)X. In the presence of methanol
the acyl group undergoes methanolysis to form the cor-
responding methyl ester a Pd(0) species and HX. The
possible occurrence of an alternative mechanism, via
formation of a Pd–CO bond, followed by association
of methanol to Pd–CO rather than insertion of CO,
was disproved by Milstein [12], while the insertion mech-
anism has been observed for cinnamyl bromide [10].
In comparison with allyl moieties, which prefer an
g3-coordination mode, benzyl moieties favor an g1-co-
ordination mode, especially if an excess of ligand is used,
thereby enhancing insertion reactions relative to other
reactions. Therefore, the mechanism of cinnamyl halide
carbonylation may well be different from that of benzyl
halides. We synthesized several potential intermediate
complexes, starting from isolated Pd(g3-cinna-
myl)(L)(Cl) complexes bearing only one equivalent of
monodentate phosphine or bidentate P–N ligand. In this
The palladium catalyzed alkoxycarbonylation of ally-
lic substrates is a powerful tool in synthetic organic
chemistry to form b–c unsaturated esters (Scheme 1)
[1–6]. The reaction can be carried out under mild condi-
tions with high atom economy and thus provides a via-
ble alternative for traditional, stoichiometric routes.
Despite its wide applicability, relatively few mecha-
nistic studies have been reported [6–16]. It has been sug-
gested that the carbonylation mechanism of allylic
substrates is similar to the carbonylation of benzyl moi-
eties. In the presence of an excess of phosphine ligands
(e.g. PR3, R = alkyl group, P/Pd P 2) this mechanism
consists of an oxidative addition of benzyl halide to a
Pd(0) species to form a (PR3)2Pd(II)(g3-benzyl)+XÀ
*
Corresponding author. Tel.: +31 20 525 5419; fax: +31 20 525
0000/6422.
E-mail address: pwnm@science.uva.nl (P.W.N.M. van Leeuwen).
Address: DSM Research B.V., Postbus 18, 6160 MD, Geleen,
1
Netherlands.
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.07.016

R.J. van Haaren et al. / Journal of Organometallic Chemistry 689 (2004) 3800–3805
3801
O
ion [18]. Warming the solution of complex 3a to room
temperature yields the methyl ester A and palladium me-
tal, thereby proving that carbonylation via the associa-
tive mechanism is a feasible process for allylic species.
Thus, provided that complex 1 is in equilibrium with
the chloride analogue of complex 2 in the presence of
CO, this mechanism is feasible for allylic chlorides.
Cl
+ CO + MeOH
O
[Pd]
Scheme 1. Palladium catalyzed methoxycarbonylation of cinnamyl
chloride.
note, we show that the alkoxycarbonylation of cinnamyl
halides can proceed via both mechanisms, insertion and
association and we report the first X-ray crystal struc-
ture of an intermediate of the insertion mechanism start-
ing from an g3-cinnamyl complex.
2.2. Insertion mechanism
The insertion reaction could be promoted either by
adding extra ligand to complex 1 [9,10,19] or by increas-
ing the pressure to 20 bar (d13C for Pd(acyl) is 236 ppm).
In the latter case the acyl complex was formed cleanly
and reversibly, presumably as the dimer [Pd(L)-
(acyl)(l-Cl)]2 (L = PCy3 or PPh3) [19]. At either higher
temperature or lower pressure complex 1 was observed.
The deinsertion of CO, leading to a Pd–CO complex,
was not observed. Thus, without added phosphine, the
chloride occupies the vacant site and stabilizes the inser-
tion product.
In an attempt to stabilize the acyl complexes in a dif-
ferent way we prepared complexes 4 bearing a hemila-
bile P–N ligand c–e (Scheme 3) [17]. Under the
conditions studied, the cationic triflate complexes
showed no interaction with CO (233–323 K, 1–50 bar
CO, in CDCl3). Using the chloride complex, at elevated
CO pressure and ambient temperature, NMR spectros-
copy shows the formation of the insertion product 5.
A similar influence of the counter ion has been observed
before [9].
Complex 5c, having the ligand with the shortest
bridge length, was formed irreversibly, but 5d and 5e
were found to be in equilibrium with 4d and 4e, respec-
tively. As can be concluded from the P–C coupling con-
stants, the acyl group coordinates cis to the phosphorus
donor (2J(P–C) = 8 Hz). This was confirmed by an X-
ray crystal structure determination of complex 5c (Fig.
1) [20].
At high temperature the g3-cinnamyl complex 4 is the
dominant species, but at low temperature the equilib-
rium shifts toward the acyl complex 5. In contrast to
other studies [8,19] we did not observe the reductive
elimination of acid chloride.
2. Results and discussion
2.1. Associative mechanism
We synthesized the (ligand)Pd(cinnamyl)Cl com-
plexes 1 (see Scheme 2). As a result of the high trans
influence of phosphorus compared to chloride combined
with the steric bulk of this group, in all cases, the syn
phenyl substituent on the allyl moiety is oriented trans
to the phosphorus ligand [17].
Under 1 bar of CO the chloride complex 1 show
slightly broadened signals in the NMR spectra, which
indicates an interaction between CO and the palladium
complex (233–298 K, CDCl3), but no new complexes
were observed. Under these conditions, the chloro com-
plex is probably in equilibrium with [(CO)(L)Pd(g3-
cinnamyl)]+[ClÀ] in which the cinnamyl is bonded in
the highly favored g3-fashion. Formation of a neutral
LPd(CO)(Cl)(g1-cinnamyl) complex, however, cannot
be ruled out completely.
Addition of silver triflate in acetonitrile to complex 1,
resulted in complete conversion to the triflate analogue
[(L)Pd(g3-cinnamyl)(MeCN)]+[ÀOTf] (2) of the putative
[(CO)(L)Pd(g3-cinnamyl)]+[ClÀ] intermediate (L = a, b).
Treatment of this ionic complex 2 with 13CO (1 bar, 293
K) resulted in the formation of compound 2, containing
both an g3-cinnamyl group and a coordinated CO lig-
and. Addition of methoxide to complex 2a at low tem-
perature leads to the formation of the novel
carbomethoxy complex 3a nearly quantitatively, in
which the cinnamyl group is still bonded in an g3-fash-
OTf
1) AgOTf
2) CO(1 bar)
MOMe
O
+ MCl
Pd
O
Pd
Pd
L
CO
L
Cl
L
CO
A
OCH3
(1a-b)
(2a-b)
(3a-b)
a = PCy3 b = PPh3
Scheme 2. Stepwise synthesis of proposed intermediates of the associative mechanism for the palladium catalyzed carbonylation of cinnamyl
chloride.

3802
R.J. van Haaren et al. / Journal of Organometallic Chemistry 689 (2004) 3800–3805
Cl
O
CO
(5 bar)
MeOH
O
O
O
P
O
Cl
P
A
c (n=1)
d (n=2)
e (n=3)
N
Pd
n
Pd
N
(a-c)
N
P
piperidine
N
(4)
(5)
B
Scheme 3. Stepwise synthesis of proposed intermediates of the insertion mechanism for the palladium catalyzed carbonylation of cinnamyl chloride.
techniques. All solvents were freshly distilled prior to
use. All reactions have been performed at room temper-
ature (292 K). High pressure NMR experiments were
carried out using a sapphire tube. The complexes were
isolated in quantitative yield (microcrystalline powder)
and were used as such in the alkylation reaction. Ele-
mental analyses were performed at the department of
Microanalysis at the Rijksuniversiteit Groningen, The
Netherlands. High Resolution Mass Spectra were re-
corded at the Department of Mass Spectroscopy at the
university of Amsterdam, The Netherlands using
FAB+ ionization on a JEOL JMS SX/SX102A four sec-
tor mass spectrometer with 3-nitrobenzyl alcohol as a
Fig. 1. Molecular structure of 5c, determined by X-ray crystallogra-
phy, showing the square planar geometry and the cis orientation of the
acyl group and the phosphorus functionality.
matrix. The synthesis of complexes 4 has been described
in literature [17]. All other ligands and reagents have
been purchased from Aldrich.
The addition of methanol to the isolated complex 5c
yielded the methyl ester (t1/2 = 4 h at 313 K). In the pres-
ence of NEt3 the methyl ester was formed instantane-
ously. When NEt3 was added without methanol, loss
of CO occurred and the g3-allyl complex 4c was formed.
Similarly, abstraction of the chloride atom by silver tri-
flate resulted in de-insertion of CO and formation of the
triflate analogue of 4c. Treating the acyl complex 5c with
piperidine yielded the amide B.
3.2. Numbering scheme of the cinnamyl moiety
Anti refers to a trans orientation to the hydrogen on
the central carbon of the allylic group, whereas syn re-
fers to a cis orientation. The numbering scheme of the
carbon atoms is C{1}H2–C{2}H–C{3}H–Ph. The num-
bering scheme of the hydrogen atoms is: Ha bonded to
C{1}(anti), Hb bonded to C{1}(syn), Hc bonded to
C{2}, Hd, bonded to C{3}.
In conclusion, we have shown that in the palladium
catalyzed alkoxycarbonylation of cinnamyl chloride
two mechanisms play a role. An associative mechanism
was observed at low pressure, while an insertion mecha-
nism was observed at high pressure or when an excess of
ligand was used. Several putative intermediates of the
catalytic alkoxycarbonylation have been synthesized
and characterized, such as 5c of which an X-ray crystal
structure could be obtained.
3.3. Preparation of complexes 1
To a yellow solution of [(C9H9)–Pd–lCl]2 [17] (100
mg, 193 mmol) in 20 ml of CH2Cl2 was added 386 mmol
of ligand. After stirring for 30 min the solvent was evap-
orated and the complexes were obtained quantitatively
as a yellow microcrystalline solids. 1a: 1H NMR
(CDCl3): d 1.25 (br s, 12H, Cy-ring); 1.5 (br s, 6H,
Cy-ring); 1.8 (br m, 12H, Cy-ring); 2.2 (q, 2.2, J1 = 12
Hz, J2 = 12 Hz, H on ipso carbon of Cy-ring); 2.65 (d,
1H, J = 11 Hz, Ha); 3.28 (d, 1H, J1 = 6 Hz, Hb); 5.20
(dd, 1H, J1 = 10 Hz, J2 = 13 Hz, Hd); 5.81 (ddd, 1H,
J1 = 13 Hz, J1 = J2 = 10 Hz, Hc); 7.2–7.3 (m, 3H, aro-
matic); 7.50 (d, 2H, J = 8 Hz, ortho-aromatic H); 31P
NMR (CDCl3): d 45.9 (s). 13C{1H} NMR (CDCl3): d
26.5; 26.8; 27.3 (d, J = 11 Hz); 27.9 (d, J = 11 Hz);
30.6; 35.1 (d, J = 18 Hz); 47.3; 100.8 (d, J = 26 Hz);
110.0; 128.0; 128.3; 129.0; 129.4; 137.1. FAB-MS:
3. Experimental
3.1. General procedures
1H and 13C NMR (300 resp. 75 MHz, TMS, CDCl3),
31P {1H} (121.5 MHz external 85% H3PO4, CDCl3)
were recorded on a Bruker DRX-300 spectrometer. All
experiments were carried out using standard Schlenk

R.J. van Haaren et al. / Journal of Organometallic Chemistry 689 (2004) 3800–3805
3803
C27H42PPd+ requires m/z = 503.2059, found 503.2029
(loss of ClÀ). 1b: 1H NMR (CDCl3): d 2.90 (d, 1H,
J = 12 Hz, Ha); 2.95 (d, 1H, J = 6 Hz, Hb); 5.36 (dd,
1H, J1 = 10 Hz, J2 = 13 Hz, Hd); 6.01 (ddd, 1H,
J1 = 13 Hz, J2 = J3 = 10 Hz, Hc); 31P NMR (CDCl3):
d 26.4 (s); Anal. Calc. for C27H24PPdCl: C, 62.20; H,
4.64. Found: C, 61.73; H, 4.82%; FAB-MS: C27H24PPd+
requires m/z = 485.0650, found 485.0669 (loss of ClÀ).
18H, aromatic); 7.80 (d, 2H, J = 5 Hz, ortho-aromatic
H). 31P NMR (CDCl3): d 25.3 (s). 13C{1H} NMR
(CDCl3): d 181.4 (s). IR: 2125 cmÀ1 (C@O).
3.6. Preparation of complex 3a
A
solution
of
10
mg
of
Pd(cinna-
myl)(PCy3)(MeCN)OTf in 0.6 ml of CDCl3 was frozen
at 195 K under an atmosphere of CO, after which 0.1
ml of a 1.0 M solution of NBu4OH in methanol was
added and frozen as well. Slowly, the frozen solution
was heated and upon melting, the solution was mixed
thoroughly. Immediately, the tube was transferred to
the precooled NMR spectrometer and the product was
characterized in situ. 1H NMR (CDCl3): d 4.47 (dd,
1H, J1 = J2 = 12 Hz, Ha); 5.00 (dd, 1H, J1 = J2 = 10
Hz, Hb); 5.58 (ddd, 1H, J1 = 8 Hz, J2 = J3 = 13 Hz,
Hd); 5.72 (m, 1H, Hc); 7.0–7.4 (m, 5H, aromatic). 31P
NMR (CDCl3): d 45.1 (d, J = 24 Hz). 13C{1H} NMR
(CDCl3): d 211.0 (d, J = 23 Hz).
3.4. Preparation of (L)Pd(g3-cinnamyl)(MeCN)OTf
(L = a, b)
To a yellow solution (20 ml) of 1 in CH2Cl2 (201 mg,
386 mmol) was added 101.2 mg (39.0 mmol) of anhy-
drous AgOTf. Upon addition, the color of the solution
became light yellow and a fine white solid precipitates.
0.5 ml of MeCN was added after stirring for 3 min. Ac-
tive carbon was added to remove the excess of AgOTf
after stirring for 15 min. Subsequent filtration and evap-
oration of the solvent yielded a light yellow microcrys-
talline powder quantitatively. The complexes should be
stored at low temperature. a: 1H NMR (CDCl3): d
1.25 (br s); 1.27 (br s); 1.38 (br s) together 15H, Cy-ring;
1.7–1.9 (br m, 18H, Cy-ring); 2.02 (s, 3H, CH3–CN);
2.90 (br d, 1H, J = 11 Hz, Ha); 3.53 (br d, 1H, J = 6
Hz, Hb); 5.59 (dd, 1H, J1 = 8 Hz, J2 = 13 Hz, Hd),
6.07 (ddd, 1H, J1 = 13 Hz, J2 = J3 = 9 Hz, Hc); 7.4 (m,
3H, aromatic); 7.6 (d, 2H, J = 8 Hz, ortho-aromatic
H). 31P NMR (CDCl3): d 47.0 (s). b: 1H NMR (CDCl3):
d 1.84 (s, 3H, CH3–CN); 3.13 (br d, 1H, J = 9 Hz, Ha);
3.47 (br b, 1H, Hb); 5.97 (dd, 1H, J1 = 13 Hz, J2 = 9 Hz,
Hd); 6.30 (ddd, 1H, J1 = 13 Hz, J2 = J3 = 9 Hz, Hc);
7.2–7.5 (m, 18H, aromatic); 7.71 (d, 2H, J = 5 Hz,
ortho-aromatic H). 31P NMR (CDCl3): d 27.6 (s). Anal.
Calc. for C30H27F3 NO3PPdS Æ CH2Cl2: C, 48.93; H,
3.84. Found: C, 48.01; H, 3.66%.
3.7. Preparation of Pd(C(O)cinnamyl)(L)(Cl)
A solution of 20 mg of 1 in CDCl3 was pressurized
with CO to the appropriate pressure (10, 20, 50 bar).
Since the product was in equilibrium with 1, it could
not be isolated and was therefore characterized in situ.
1
a: H NMR (CDCl3): d 1.0–2.0 (br m, 33H, Cy-rings);
3.8 (br d, 2H, J = 5 Hz, CH2); 6.3 (d, 1H, J = 18 Hz,
–CH@CH–Ph); 6.50 (m, 1H, –CH@CH–Ph); 7.0–7.6
(br m, 5H, aromatic). 31P NMR (CDCl3): d 41.3 (s);
1
13C: 236.0 (s). b: H NMR (CDCl3): d 3.1 (br b, 2H,
CH2); 5.63 (br b, CH@CH–Ph); 6.08 (m, 1H, –
CH@CH–Ph); 7.0–7.6 (br m, 5H, aromatic). 31P NMR
(CDCl3): d 28.6 (s); 13C: 229.2 (s).
3.8. Preparation of complexes 5
3.5. Preparation of complexes 2
A solution of 20 mg of 4 in CDCl3 was pressurized
with CO to 20 bar. The pure acyl complexes 5c and 5d
could also be obtained by preparation in an autoclave.
The product was precipitated by addition of hexane
(not pentane) at high pressure (20 bar). The complex
was isolated in quantitative yield by removal of the sol-
vent and slowly drying overnight (not evaporation in va-
CO was bubbled through a solution of 10 mg of
(L)Pd(g3-cinnamyl)(MeCN)OTf (L = a, b) in CDCl3.
The light yellow solution turned colorless within one
minute (within seconds for the more basic ligands).
The product could not be isolated by either evaporation
of the solvent or by precipitation using pentane or hex-
ane and was therefore characterized in situ. 2a: 1H
NMR (CDCl3): d 1.2–1.4 (br m, 15H, Cy-ring); 1.7–
2.2 (br m, 18H, Cy-ring); 3.56 (d, 1H, J = 13 Hz, Ha);
4.17 (d, 1H, J = 6 Hz, Hb); 6.3 (ddd, 1H, J1 = 7 Hz,
J2 = J3 = 9 Hz, Hd); 6.56 (br m, 1H, Hc); 7.4 (br m,
3H, aromatic); 7.78 (d, 2H J = 8 Hz, ortho-aromatic
H). 31P NMR (CDCl3): d 48.5 (s). 13C{1H} NMR
1
cuo). 5c: H NMR (CDCl3): d 3.48 (d, 2H, J = 6 Hz,
–C(O)–CH2–); 5.06 (d, 2H, J = 21 Hz, O–CH2);
5.88 (d, 1H, J = 16 Hz, –CH@CH–Ph); 6.20 (m, 1H,
–CH@CH–Ph); 7.0–7.8 (br m, 18H, aromatic); 9.38 (br
b, 1H, ortho-pyridine). 31P NMR (CDCl3): d 119.9 (s).
13C{1H} NMR (CDCl3): d 226.5 (d, J = 8 Hz); FAB-
MS: As a result of the loss of ClÀ, decomposition oc-
curred in the spectrometer. M+ could not be observed,
1
(CDCl3): d 181.9. IR: 2115 cmÀ1 (C@O). 2b: H NMR
(CDCl3): d 3.58 (br d, 1H, J = 11 Hz, Ha); 3.86 (br b,
1H, Hb); 6.44 (ddd, 1H, J1 = J2 = 10 Hz, J3 = 9 Hz,
Hd); 6.59 (br t, 1H, J1 = J2 = 11 Hz, Hc); 7.2–7.5 (m,
a
signal at m/z = 544.0669 corresponding to
C28H27NO2Pd+, proving the existence of a Pd complex
bearing two oxygen atoms (one of the ligand and one

3804
R.J. van Haaren et al. / Journal of Organometallic Chemistry 689 (2004) 3800–3805
of the carbonyl) was observed. 5d: 1H NMR (CDCl3): d
3.51 (d, 2H, J = 7 Hz, –C(O)–CH2–); 3.60 (br t, 2H,
J = 5 Hz, –CH2–Ar); 4.11 (dt, 2H, J = 14 Hz, J = 6
Hz, O–CH2); 6.05 (d, 1H, J = 16 Hz, –CH@CH–Ph);
6.28 (m, 1H, –CH@CH–Ph); 7.0–7.7 (br m, 18H, aro-
matic); 8.97 (d, 1H, J = 5 Hz, ortho-pyridine). 31P
NMR (CDCl3): d 107.4 (s). 13C{1H} NMR (CDCl3): d
38.4; 56.3; 68.0; 124.2; 126.7; 127.8; 129.0; 129.5;
130.1; 131.6; 132.8; 137.2; 152.0; 158.1; 229.6 (d, J = 6
The hydrogen atoms were calculated and a riding
model was used during refinement. Full-matrix least-
squares refinement on F2, anisotropic for the non-hydro-
gen atoms and isotropic for the hydrogen atoms,
converged to R1 = 0.069, wR2 = 0.075, (D/r)max = 0.03,
S = 1.5. A weighting scheme w = [7000 + 0.01r(Fobs)2 +
0.01/(r(Fobs))]À1 was used. The secondary isotropic
extinction coefficient [21,22,24–26] refined to G =
1181(30). A final difference Fourier map revealed a resid-
1
Hz). 5e: H NMR (CDCl3): d 1.94 (br b, 2H, –CH2–
ual electron density between À1.56 and 2.04 e AÀ3 in the
˚
CH2–CH2–); 3.41 (d, 2H, J = 7 Hz, –C(O)–CH2–); 3.56
(br b, 4H,, O–CH2 + –CH2–Ar); 6.06 (d, 1H, J = 16
Hz, –CH@CH–Ph); 6.29 (m, 1H, –CH@CH–Ph); 7.0–
7.7 (br m, 18H, aromatic); 8.37 (d, 1H, J = 5 Hz,
vicinity of the Pd. Scattering factors were taken from
Cromer and Mann [27], International Tables for X-ray
Crystallography [28]. The anomalous scattering of
Pd, P and Cl was taken into account [29]. All calcula-
tions were performed with XTAL3.7 [30] unless stated
otherwise.
ortho-pyridine). 31P NMR (CDCl3):
13C{1H} NMR (CDCl3): d 227.5.
d 118.2 (s).
3.9. Characterization of A and B
Acknowledgement
A: 1H NMR (CDCl3): d 3.22 (d, 2H, J = 7 Hz, CH2);
3.68 (s, 3H, CH3); 6.25 (m, 1H, –CH@CH–Ph); 6.45 (d,
1H, 16 Hz, –CH@CH–Ph); 7.0–7.8 (m, 5H, aromatic).
This research was carried out with financial support
from DSM Research B.V. (RJVH) and with a subsidy
from the Ministry of Economic Affairs as part of the
E.E.T. program (Grant nrs EETK 97107 and EETK
99104) for clean chemistry (RJVH, GPFVS).
1
B: H NMR (CDCl3): d 1.6 (m, 6H, N–(CH2–CH2)2–
CH2); 3.10 (d, 2H, J = 7 Hz, @CH–CH2–C(O)–); 6.31
(m, 1H, Ph–CH@CH–CH2–C(O)–); 6.48 (d, 1H, J = 16
Hz, Ph–CH@CH–CH2–C(O)–); 7.2–7.9 (m, 5H, aro-
matic H).
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3.10. Crystal structure determination of 5c
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˚
C28H25ClNO2PPd, Mw = 580.3, triclinic, P1, a =
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˚
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À3
˚
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˚
0.040–0.630 A (3.5 6 h 6 76.1ꢁ). Two reference reflec-
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least-squares fitting procedure using 23 reflections with
40.04 6 h 6 41.92ꢁ. Corrections for Lorentz and polari-
sation effects were applied. Absorption correction was
performed with the program PLATON [21] following
the method of North et al. [22] using W-scans of five
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