Effect of the ligand nature on the regioselectivity of the styrene carbonylation in the presence of palladium(II) complexes

Full text of DOI:10.1134/S0012500810090053

ISSN 0012ꢀ5008, Doklady Chemistry, 2010, Vol. 434, Part 1, pp. 226–232. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © N.V. Zvyagintsev, O.L. Eliseev, L.T. Kondrat’ev, A.L. Lapidus, 2010, published in Doklady Akademii Nauk, 2010, Vol. 434, No. 2, pp. 189–195.
CHEMISTRY
Effect of the Ligand Nature on the Regioselectivity
of the Styrene Carbonylation
in the Presence of Palladium(II) Complexes
N. V. Zvyagintsevb, O. L. Eliseeva, L. T. Kondrat’evb,
and Corresponding Member of the RAS A. L. Lapidusa
Received March 30, 2010
DOI: 10.1134/S0012500810090053
This study dealt with the influence of halide ligands the most important reaction states were considered,
and the effect of the acidity of hydride palladium
π
on the regioselectivity of the styrene carbonylation
reaction in ionic liquids without phosphine ligands.
The stage of migration insertion of styrene into the
complexes with styrene on the yield of complexes was
examined.
Pd–H bond in the hydride
π
complex [HPdX(styꢀ
Studying the mechanism of the styrene carbonylaꢀ
rene)L] (II; X = Cl, Br) was modeled. The energies of tion reaction
COOR'
COOR'
[Pd]
+ CO + R'OH
+
R
R
R
(R' = H, Alk)
is of considerable interest for the development of theꢀ
ory of metal complex catalysis, as well as in the context
of the practical use of this reaction in synthesis of
pharmaceutical preparations.
The fact that an acidic promoter should be present
in the system for the reaction to occur [9–11] is eviꢀ
dence in favor of the hydride mechanism of carbonyꢀ
lation, which is consistent with the literature data [5].
This mechanism implies the formation of hydride palꢀ
The reaction yields 1ꢀ and 2ꢀarylpropionic acids,
and the regioselectivity of this reaction depends on
temperature, the medium, pressure, and the presꢀ
ence of a certain acidic promoter in the system
ladium
π
complexes with styrene. The influence of
pressure on the regioselectivity of the reaction indiꢀ
cates that catalytically active complexes are hydride
[1⎯ 8].
palladium
π
complexes with styrene also liganded by
the CO molecule and halide anion. The regioselectivꢀ
ity of the entire reaction is determined at the stage of
migration insertion of styrene into the Pd–H bond in
a Zelinsky Institute of Organic Chemistry,
Russian Academy of Sciences, Leninskii pr. 47, Moscow,
119991 Russia
b Russian State University of Tourism and Service,
ul. Glavnaya 99, Cherkizovo, Pushkino region,
Moscow oblast, 141221 Russia
the
π
complex to produce branched and linear Alk–Pd
complexes.
226

EFFECT OF THE LIGAND NATURE ON THE REGIOSELECTIVITY
227
Pd2+
CO, H2
Pd0
HX, 2L
COOH
Ph
Ph
COOH
VI
V
H
Pd
L
L
H2O
H2O
X
I
Ph
O
Pd
X
L
Ph
–L
L
Pd
X
Ph
IVa
O
IVb
CO
CO
Ph
H
Pd
L
X
L
L
II
L
L
Pd
L
Ph
Ph
Pd
L
X
X
IIIa
IIIb
(X = Cl, Br; L = PPh3, CO)
Scheme 1.
As shown in Scheme 1, the addition of the CO molꢀ dependent on the halogen incorporated in the nascent
ecule to complexes IIIa and IIIb leads to acyl comꢀ
plexes IVa and IVb, which are hydrolyzed to give corꢀ
responding phenylpropionic acids with the closure of
palladium complex. We theoretically studied the
transformations of hydride complex II to Alk–Pd
complexes IIIa and IIIb (X = Cl, Br; L = CO) with the
aim of elucidating the role of halide ligands in the
course of the stage of migration insertion of styrene
π
the catalytic cycle on the initial Pd–H complex
I.
The available experimental data demonstrate that
the regioselectivity of the reaction is considerably into the Pd–H bond. In this paper, we report the
Table 1. Selected geometrical parameters of complexes II, S1, and S2 (X = Cl, Br) (bond lengths are in picometers, bond angles
are in degrees)
X = Cl
X = Br
Parameter
II
S1
S2
II
S1
S2
Pd–C(α
Pd–C(β
C(α
Pd–H
Pd–X
Pd–CO
C–O
)
230.2
241.6
137.6
155.3
243.8
192.1
113.9
146.8
77.6
162.9
179.0
178.9
–68.6
112.5
215.0
239.2
141.4
160.3
240.1
215.0
114.0
141.4
81.5
175.8
177.2
169.9
–7.6
205.5
240.6
148.8
187.6
236.1
201.6
114.0
148.8
83.9
174.0
175.0
158.2
–3.7
230.7
240.7
137.6
155.3
255.2
191.9
114.0
108.7
77.1
161.7
179.4
178.5
–66.7
114.7
215.4
238.2
141.4
159.8
251.0
195.5
114.0
148.8
80.9
174.9
178.4
169.7
–10.3
169.3
205.8
240.4
149.0
188.3
247.7
201.0
114.0
151.2
836.9
172.7
176.5
156.2
–6.3
)
)–C(
β
)
C(
PdC(
β
)–C
)C( )
α
β
CPdC(O)
OCPd
HPdX
XPdC1C2
HPdC(
α
)C(
β
)
172.1
176.7
172.1
DOKLADY CHEMISTRY Vol. 434
Part 1
2010

228
ZVYAGINTSEV et al.
X
Pd
Pd
X
Pd
X
C(α)
C(β)
II
S1
S2
Pd
X
IIIb
Fig. 1. Geometric structures of complexes II, IIIb, S , and S (X = Cl, Br; L = CO).
1 2
results of studying the structures of complexes II
,
IIIa
,
plex S1 is broken, and the hydrogen atom forms a
chemical bond to the C( atom, which gives complex
S2. In the next step, complex S2 directly interacts with
the CO molecule to give complex IIIb. Selected geoꢀ
metric parameters (bond lengths, interatomic disꢀ
and IIIb and intermediate complexes that form at this
stage of the reaction, as well as the calculated energies
of all transformations under consideration.
β)
Calculations were performed by the B3LYP
method with the combined LANL2TZ + TZV +
6ꢀ31Gdp basis set in which the LANL2TZ ECP basis
set (with pseudopotential) was used for the palladium
atom, the DZV basis set was used for the halogen
atoms, and the 6ꢀ31G(d, p) basis set was used for the
remaining atoms. All calculations were performed
with the PC GAMESS/Firefly 7.1 program package
[13, 14]. The geometric structures of the complexes
were studied with full geometry optimization, and
Hessians were calculated for all the structures.
tances, bond and torsion angles) of complexes II, S1,
and S2 (X = Cl, Br), reflecting the change in their
geometries in the course of reaction, are presented in
Table 1. The data were obtained by the
B3LYP/LANL2TZ + TZV + 6ꢀ31Gdp method.
According to Table 1, for any type of halogen in the
complexes, the geometric parameters change only
slightly. The Pd–X bond length mainly changes.
The formation of branched complex IIIa from II
also proceeds in several intermediate steps. The strucꢀ
tures of complexes IIIa and intermediate complexes
Figure 1 shows the spatial structures of hydride
complex II, Alk–Pd complex IIIb (X = Cl, Br), and
π
S3,
S4, and S5 (X = Cl, Br) are shown in Fig. 2.
In the course of reaction in hydride complex II
the hydrogen atom is shifted to the ꢀcarbon atom and
intermediate complexes S1 and S2, which form at this
stage of the reaction.
π
,
α
The vinyl carbon atom of styrene not bonded to the
the X ligand is rotated about the Pd–CO bond, which
results in complex S3 (with one negative eigenvalue in
the Hessian). Further transformations of transition
state S3 leads to complex S4, which is accompanied by
phenyl ring is denoted as C(
bonded to the phenyl ring is denoted as C(
We found that hydride complex II, through the rotaꢀ
tion of the Pd–H and Pd–X bonds in the course of
α)
, and the carbon atom
β
)
(Fig. 1).
π
reaction, transforms to intermediate complex S1 an increase in the Pd–H bond length. The arrangeꢀ
ment of the substituents about the C( ) and C(
value of the Hessian). Then, the Pd–H bond in comꢀ atoms becomes typical of the sp3 hybrid state of the
α
β
)
(which is a transition state and has one negative eigenꢀ
DOKLADY CHEMISTRY Vol. 434
Part 1
2010

EFFECT OF THE LIGAND NATURE ON THE REGIOSELECTIVITY
229
X
X
X
Pd
Pd
Pd
S3
S4
S5
X
Pd
IIIa
Fig. 2. Structure of complex IIIa and intermediate complexes
S
,
S
, and S (X = Cl, Br; L = CO).
5
3
4
carbon atom. Further study of the reaction path
As follows from Table 4, the type of halogen has a
showed that complex S4 either interacts with the CO considerable effect on the energies of formation of
complexes S2 and S4, which directly interact with the
molecule to form complex IIIa or forms
3ꢀbenzyl
η
complex S5. The existence of
3ꢀbenzyl complex S5
η
CO molecule. When the catalytic complex is liganded
by the chloride anion, the formation of complex S2
requires an energy input of ~3.16 kJ/mol, whereas the
presence of the bromide anion in the reactive complex
leads to the release of ~–1.72 kJ/mol. At the same
time, the formation of complex S4 when the catalyst
contains the chloride anion is more favorable than in
the presence of the bromide anion. Thus, the chloride
anion favors the formation of complex S4 to a greater
extent than the bromide anion. This is supported by
the experimental data on the yield of hydratropic acid
was experimentally proved, and its influence on the
regioselectivity of the styrene carbonylation has been
discussed in the literature (see, e.g., [6]). Table 2 comꢀ
pares the geometric parameters of complexes II, S3,
and S4 (X = Cl, Br) most significant for studying the
reaction path. The data were obtained by the
B3LYP/LANL2TZ + TZV + 6ꢀ31Gdp method.
To study the influence of the halide ligands on the
regioselectivity of the reaction, we compared the enerꢀ
gies of all transformations. Table 3 summarizes the
total energies Etot of complexes II, IIIa, IIIb, S1, S2,
S3(X), S4(X), and S5(X) (X = Cl, Br) calculated by the
(V) and hydrocinnamic acid (VI) formed in the styꢀ
rene carbonylation reaction in ionic liquids, such as
tetrabutylammonium chloride (TBAC) and tetrabutyꢀ
lammonium bromide (TBAB).
B3LYP/LANL2TZ + TZV + 6ꢀ31Gdp method.
Table 5 summarizes the data on the styrene converꢀ
sion and the overall yield and the ratio between the
From the results obtained, we calculated the energy
effects (
stage. The
regioselectivity of the reaction are listed in Table 4.
Δ
E
Δ
) of the transformations that occur at this
branched (
V) and linear (VI) acids (b : l) in the final
E
values most significant for studying the
product obtained with the use of the Pd(OAc)2 and
DOKLADY CHEMISTRY Vol. 434
Part 1
2010

230
ZVYAGINTSEV et al.
Table 2. Selected geometrical parameters of the transition states of complexes II, S3, and S4 (X = Cl, Br) (bond lengths are in
picometers, bond angles are in degrees)
X = Cl
X = Br
Parameter
II
S3
S4
II
S3
S4
Pd–C(
α
)
230.2
241.6
137.6
155.3
243.8
192.1
113.9
146.8
77.6
224.8
231.9
140.4
158.4
242.4
194.7
114.0
147.3
69.3
243.5
210.6
149.4
197.6
239.1
200.1
114.0
146.8
59.2
230.7
240.7
137.6
155.3
255.2
191.9
114.0
108.7
77.1
225.6
231.7
140.4
157.8
253.4
194.5
114.0
147.3
69.8
243.6
210.8
149.6
198.2
250.6
199.5
114.0
146.7
59.2
Pd–C(
β
)
C(
α
)–C(
β
)
Pd–H
Pd–X
Pd–C(O)
C–O
C(
PdC(
C(
β
)–C
α
)C(
β
)
α
)PdC(O)
162.9
179.0
178.9
–68.6
112.5
177.4
177.3
171.6
–20.2
163.0
174.0
174.1
152.5
–25.5
166.4
161.7
179.4
178.5
–66.7
114.7
177.4
178.3
172.9
–18.7
164.3
172.8
175.2
151.6
–25.4
165.9
OCPd
HPdX
XPdC1C2
HPdC(
α
)C(β)
Pd(PPh3)2 salts in ionic liquids. pꢀToluenesulfonic triphenylphosphine, and halide anions [HPdX(styꢀ
rene)PPh3] (X = Cl, Br) (Fig. 3).
acid and hydrochloric acid were used as the acid proꢀ
moter. The reaction conditions were as follows:
4 mmol of styrene, 20 mmol of water, 0.02 mmol of
[Pd], 0.8 mmol of pꢀtoluenesulfonic acid, 2 g of TBAC
or TBAB, 5 mL of heptane [13].
Table 6 lists the partial charges calculated by the
B3LYP/DZVP + TZV + 6ꢀ31Gdp method (for the
palladium atom, the DZVP basis set was used; for the
carbon and hydrogen atoms of the triphenylphosphine
molecule, the 3ꢀ21G basis set was used).
Information on the influence of the ligands on the
acidity of the hydride palladium complexes with styꢀ
π
As follows from Table 6, the substitution of the broꢀ
mide anion for the chloride anion has almost no effect
on the partial atom on the carbon, palladium, and
hydrogen atoms; therefore, the type of halogen slightly
rene is of special interest for studying the regioselectivꢀ
ity of the styrene carbonylation reaction. For comparꢀ
ison of the acidities of the complexes, we considered
also the hydride palladium
π
complexes with styrene,
affects the acidity of the hydride complex. In the case
π
Table 3. Total energies Etot (au) of complexes II, IIIa, IIIb,
S1, S2, S3, S4, and S5 (X = Cl, Br)
Table 4. Influence of the halogen on the energy effects (kJ/mol)
of intermediate transformations of the stage of migration inꢀ
sertion of styrene into the Pd–H bond
Parameter
X = Cl
X = Br
Δ
E
X = Cl
X = Br
II
–1010.58155
–1123.934372
–1123.930109
–1010.573002
–1010.580346
–1010.576171
–1010.594355
–1010.60458
–3121.987988
–3235.341757
–3235.3384
Etot
Etot
Etot
Etot
Etot
Etot
Etot
Etot
(
(
(
(
(
(
(
(
S
S
S
S
S
S
S
1) – Etot
2) – Etot
1) – Etot
3) – Etot
4) – Etot
3) – Etot
2) – Etot
(
(
(
(
(
(
(
II
)
)
22.4446
3.16294
19.4261
–1.715239
21.14131
14.4977
IIIa
IIIb
S1
II
S2
)
19.28167
14.1239
–3121.980589
–3121.988641
–3121.982466
–3121.997039
–3122.01238
II
)
S2
II
)
–33.61952
47.7434
–23.76497
38.26272
22.0497
S3
S4
)
S4
S4
)
36.7825
S5
IIIa) – Etot
(IIIb
)
–11.1917
ꢀ8.81275
DOKLADY CHEMISTRY Vol. 434
Part 1
2010

EFFECT OF THE LIGAND NATURE ON THE REGIOSELECTIVITY
231
P
X
Pd
Fig. 3. Structure of the hydride π complex [HPdX(styrene)PPh ] (X = Cl, Br; L = PPh ).
3 3
of the complexes with triphenylphosphine branched acid, which is confirmed by experimental
[HPdX(styrene)PPh3] (X = Cl, Br), the charge on the
hydrogen atoms changes considerably. The data on the
partial charges show that the complexes with the CO
molecule have a higher acidity than the complexes
with triphenylphosphine.
data. We demonstrated that, in the hydride complexes
with halide anions and CO, the nature of the halogen
(chlorine or bromine) has no effect on the acidity of
Table 5. Experimental data on the styrene conversion and the
yield and ration of hydratropic and hydrocinnamic acids (b : l)
Thus, we comprehensively studied the mechanism
of the migration insertion of styrene into the Pd–H
Converꢀ Acid yield,
bond in complex II. The geometries of complexes II
,
Catalyst
IL
b : l
sion, %
%
IIIa IIIb, and all intermediate complexes were conꢀ
,
Pd(OAc)2 TBAB*
TBAB**
TBAC*
97.1
93.5
22.2
87.2
83.0
16.0
0.8
1.0
6.3
sidered. The calculation results showed that halogens
have a significant effect on the energy of the migration
insertion of styrene into the Pd–H bond in complex
II. The chloride anion promotes the transformation of
Pd(PPh3)2 TBAB*
TBAB**
TBAC*
33.1
76.1
100
29.2
69.2
89.5
1.0
1.4
7.2
hydride
π
complex II into complex S4. Inasmuch as
this stage determines the regioselectivity of the entire
reaction, the presence of the chloride anion in the catꢀ
alytic complex is favorable for the formation of a
Note: IL stands for ionic liquids. Promoters are *—pꢀCH C H SO H
3
6
4
3
and **—HCl.
DOKLADY CHEMISTRY Vol. 434
Part 1
2010

232
ZVYAGINTSEV et al.
Table 6. Mulliken charges on the atoms of the hydride palladium π complexes with styrene and different ligands
Atomic charge, au
π Complex
H
Pd
X
C(α
)
C(β)
[HPdClCO(styrene)]
[HPdCl(styrene)PPh3]
0.008470
0.009072
0.033833
0.005932
–0.406539
–0.322479
–0.279935
–0.274910
–0.131644
–0.129654
–0.01233
–0.01714
0.057556
0.005751
–0.478243
–0.419937
–0.278868
–0.273290
–0.168963
–0.170327
7. Rieu, J.ꢀP., Boucherle, A., Cousse, H., and Mouzin, G.,
Tetrahedron, 1986, vol. 42, p. 4095.
8. Sonawane, H.R., Bellur, N.S., Ahuja, J.R., and
the entire complex. The substitution of the tripheꢀ
nylphosphine molecule for the CO molecule considꢀ
erably acidifies the hydride complex.
Kulkarni, D.G., Tetrahedron, 1992, vol. 3, p. 163.
9. Lapidus, A.L., Eliseev, O.L., Stepin, N.N., and Bondꢀ
arenko, T.N., Izv. Akad. Nauk, Ser. Khim., 2004, no. 11,
p. 2458.
10. Eliseev, O.L., Stepin, N.N., Bondarenko, T.N., and
Lapidus, A.L., Dokl. Chem., 2005, vol. 401, part 2,
pp. 59–61 [Dokl. Akad. Nauk, 2005, vol. 401, no. 4,
pp. 486–490].
11. Lapidus, A., Eliseev, O., Bondarenko, T., and
Stepin, N., J. Mol. Catal. A: Chem., 2006, vol. 252,
p. 245.
12. Balazs, A., Benedek, C., and Toros, S., J. Mol. Catal. A:
Chem., 2006, vol. 244, p. 105.
REFERENCES
1. Kiss, G., Chem. Rev., 2001, vol. 101, p. 3435.
2. Oi, S., Nomura, M., Aiko, T., and Inoue, Y., J. Mol.
Catal. A: Chem., 1997, vol. 115, p. 289.
3. Yoon, J.ꢀY., Jang, E.J., Lee, K.H., and Lee, J.S.,
J. Mol. Catal. A: Chem., 1997, vol. 118, p. 181.
4. del Rio, I., Ruiz, N., and Claver, C., Inorg. Chem. Comꢀ
mun., 2000, vol. 3, p. 166.
5. Papadogianakis, G., Verspui, G., Maat, L., and Shelꢀ
don, R.A., Catal. Lett., 1997, vol. 47, p. 43.
13. Granovsky, A.A., PC GAMESS/Firefly, 7.1.
6. Bonnet, M.C., Monteiro, A.L., and Tkatchenko, I., 14. Schmidt, M.W., Baldridge, K.K., Boatz, J.A., et al.,
J. Mol. Catal. A: Chem., 1999, vol. 143, p. 131. J. Comput. Chem., 1993, vol. 14, pp. 1347–1363.
DOKLADY CHEMISTRY Vol. 434
Part 1
2010