Carbonylation (hydroformylation and hydroalkoxycarbonylation) of styrene in the presence of transition metal-ferrocene-based aminophosphine systems

Article abstract of DOI:10.1016/S0022-328X(98)00478-1

The PtCl₂(L)-type platinum complexes of the ferrocenyl ligands, (S_c,S _m)-1-diphenylphosphino-α-N-N-dimethyl-amino[2,3] tetramethyleneferrocene (1) and (S_c,S _m)-1,1′-bis(diphenylphosphino)-α-N,N-dimethylamino[2,3] tetramethylene ferrocene (2) have been synthesised. Both the 'preformed' and in situ catalysts have been used in hydroformylation of styrene. In spite of low enantioselectivities and activities, the ferrocenyl based systems proved to be of interest from theoretical point of view. The ligand influence on regio- and enantioselectivity has been investigated in systems containing either only one of the ferrocenyl ligands or one ferrocenyl ligand together with bdpp ((2S,3S)-2,4-bis(diphenylphosphino)pentane). The coordination of the respective ligands to platinum in the catalytic process can be deduced from results obtained with the 'mixed ligand system'. The rhodium in situ catalysts containing either 1 or 2 are active in hydroformylation but the ee-s obtained with styrene are low. In the presence of ligand 1, the palladium-catalysed hydromethoxycarbonylation of styrene resulted in the predominant formation of the branched regioisomer, in case of 2 mostly the linear product was formed.

Full text of DOI:10.1016/S0022-328X(98)00478-1

Journal of Organometallic Chemistry 563 (1998) 37–41
Carbonylation (hydroformylation and hydroalkoxycarbonylation) of
styrene in the presence of transition metal–ferrocene-based
aminophosphine systems
Brigitte Jedlicka a, Walter Weissensteiner a, Tama´s Ke´gl b, La´szlo´ Kolla´r b,c,
*
a Institut fu¨r Organische Chemie, Uni6ersita¨t Wien, Wa¨hringerstrasse 38, A-1090 Wien, Austria
b Department of Organic Chemistry, Uni6ersity of Veszpre´m, P.O. Box 158, H-8201 Veszpre´m, Hungary
c Department of Inorganic Chemistry, Janus Pannonius Uni6ersity, P.O. Box 266, H-7624 Pe´cs, Hungary
Received 13 November 1997
Abstract
The PtCl2(L)-type platinum complexes of the ferrocenyl ligands, (Sc,Sm)-1-diphenylphosphino-h-N,N-dimethyl-
amino[2,3]tetramethyleneferrocene (1) and (Sc,Sm)-1,1%-bis(diphenylphosphino)-h-N,N-dimethylamino[2,3]tetramethylene fer-
rocene (2) have been synthesised. Both the ‘preformed’ and in situ catalysts have been used in hydroformylation of styrene. In
spite of low enantioselectivities and activities, the ferrocenyl based systems proved to be of interest from theoretical point of view.
The ligand influence on regio- and enantioselectivity has been investigated in systems containing either only one of the ferrocenyl
ligands or one ferrocenyl ligand together with bdpp ((2S,3S)-2,4-bis(diphenylphosphino)pentane). The coordination of the
respective ligands to platinum in the catalytic process can be deduced from results obtained with the ‘mixed ligand system’. The
rhodium in situ catalysts containing either 1 or 2 are active in hydroformylation but the ee-s obtained with styrene are low. In
the presence of ligand 1, the palladium-catalysed hydromethoxycarbonylation of styrene resulted in the predominant formation
of the branched regioisomer, in case of 2 mostly the linear product was formed. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Carbonylation; Hydroformylation; Platinum; Palladium; Ferrocene; Phosphine; Nuclear magnetic resonance
1. Introduction
A number of mono- and bidentate phosphines have
been used as both chiral and achiral ligands in transi-
tion metal complexes showing hydroformylation and/or
hydroalkoxycarbonylation activity [5]. Especially chiral
diphosphines of C2 symmetry have been investigated
thoroughly as ligands in asymmetric hydroformylation
reactions [6–12]. Diphosphines possessing diphenyl-
phosphino groups in different environments have also
been reported as efficient ligands [13]. However, recent
studies with heterobidentate ligands show the impor-
tance of different donor atoms in rhodiumcatalysed
reaction [14,15].
The importance of carbonylation reactions has been
documented in numerous studies, reporting mainly on
applications in organic synthesis or on reaction mecha-
nisms [1]. Among these reactions hydroformylations
(and hydroalkoxycarbonylations) predominate [2]. In
particular, a large number of simple and functionalised
olefins have been investigated with respect to products
of practical interest [3]. Large efforts have been made in
order to apply asymmetric hydroformylation reactions
to the synthesis of chiral building blocks and of biolog-
ically important derivatives [4].
Ferrocene-based chiral phosphines and aminophos-
phines form transition metal complexes which have
already been identified as active catalysts in a variety of
enantioselective reactions including hydrogenation, hy-
* Corresponding author. Fax: +36 72 327622/4680.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00478-1

38
B. Jedlicka et al. / Journal of Organometallic Chemistry 563 (1998) 37–41
Fig. 1. The synthesis of platinum complexes containing ferrocenyl ligands, 1 and 2.
drosilylation, cross-coupling reactions and aldol con-
densation [16,17]. Surprisingly, to the best of our
knowledge, no example for their applicability in enan-
tioselective carbonylation reactions has been reported,
yet.
In this paper we describe the synthesis and character-
isation of palladium and platinum complexes modified
with enantiopure homoannularly bridged ferrocenyl
aminophosphine or aminobisphosphine ligands and dis-
cuss their application in hydroformylation and hy-
droalkoxycarbonylation reactions.
ligand 1 also the P–N complex (1c) is formed but with
2 depending on the reaction conditions, a P–P complex
or a Pd3(2)2-type complex (2c) is isolated. In the latter
case each ferrocene entity (2) forms a P–N chelate with
one PdCl2 unit while the third palladium bridges the
ferrocenes via the trans coordinating PPh2 functionali-
ties bound to the monosubstituted Cp-rings. The syn-
thesis and characterisation of the Pd complexes of both
ligands have been reported earlier [18,20,21].
Both the chemical shifts and coupling constants listed
in Table 1 reflect the different types of coordination in
complexes 1a and 2a. In case of 1a the coordination of
nitrogen was proved by the Pt satellites of the proton
3
2. Results and discussion
signals (3J(195Pt,1H)=26 Hz, J(195Pt,1H)=30 Hz) of
the NMe2 methyl groups. In addition, the large differ-
ence in the chemical shifts l(31P) of 1a and 2a is
indicative of a P–N coordination in 1a.
2.1. Synthesis and characterisation of palladium and
platinum complexes
The configuration of complex 1b could also be de-
duced from the NMR data. From the coupling con-
stants J(31P,117Sn) and J(31P,119Sn) (186 and 195 Hz,
respectively) it follows that in case of 1a tin(II)chloride
is inserted into the Pt–Cl bond trans to nitrogen giving
1b with the trichlorostannato ligand cis to phosphorus.
The ‘high-field’ phosphorus signal of 2a was assigned
to the phosphorus bound to the Cp-ring possessing the
homoannularly bridged dimethylamino group. The in-
sertion of SnCl2 most likely takes place into Pt–Cl
bond trans to this phosphorus (P1) which is indicated
by the downfield shift of 2.2 ppm of this signal due to
The ferrocenyl ligands ((Sc,Sm)-1-diphenylphosphino-
h-N,N-dimethylamino[2,3]-tetramethyleneferrocene (1)
and
(Sc,Sm)-1-1%-bis(diphenylphosphino)-h-N,N-di-
methylamino[2,3]tetramethyleneferrocene (2) [18–20])
were reacted with PtCl2(PhCN)2 precursor resulting in
easily accessible la and 2a, respectively (Fig. 1). Ligand
1 forms a P–N chelating platinum complex by replac-
ing benzonitrile ligands of the respective precursors.
However, on reacting with PtCl2(PhCN)2 the P–P–N
derivative (2) acts as diphosphine leaving the amino
functionality uncoordinated. In case of palladium, with

B. Jedlicka et al. / Journal of Organometallic Chemistry 563 (1998) 37–41
39
Table 1
31P-NMR data of Pt complexes containing ferrocenyl ligands, 1 and 2
Complexes
lP
1J(195Pt,31P)
J(P1,P2)
2J(31P,117Sn)
2J(31P,119Sn)
ppm
Hz
Hz
Hz
Hz
PtCl2(1)
PtCl(SnCl3)(1)
PtCl2(2)
(1a)
(1b)
(2a)
−10.0
2.0
4025
2933
4034
4012
3843
3881
—
—
7.2
—
186
—
—
195
—
lP1=14.5
lP2=19.2
lP1=16.7
lP2=18.9
PtCl(SnCl3)(2)
(2b)
4.8
n.a.
n.a.
with Pt-(2S,4S)-bdpp-SnCl2 system [10]. In case of 1a-
(2S,4S)-bdpp-SnCl2 neither the absolute configuration
nor the ee are characteristic for the bdpp containing
system. It can be stated that the results obtained with
catalytic systems containing ‘mixed ligands’ (1 and
bdpp or 2 and bdpp) are substantially different from
those obtained with 1a or 2a. Since the catalytic results
are characteristic neither for the bdpp- nor the ferro-
cenyl-containing systems, and furthermore, the activi-
ties are between the two systems 1a and PtCl2(bdpp),
during the catalytic reaction a coordination of both
ligands to platinum can be assumed in the ’mixed
ligand’ system. (In chiral diphosphine–monophosphine
systems the unexpected effect of the ligands on ee-s
have already been observed in hydrocarbalkoxylation
[22], hydrogenation [23] and hydroformylation [24].)
The reason for the observed results could be a
monodentate coordination of the potentially bidentate
ligands 1 and 2 in the transition state complex responsi-
ble for the stereochemical outcome of the reaction.
Both the low activity and enantioselectivity obtained
in the presence of 1 and 2 indicate that the bite angles
of the ferrocenyl ligands are too small upon coordina-
tion to rhodium(I) and platinum(II) possessing rela-
tively large ionic radius. Furthermore, the amine
functionality of the ligands might be responsible for
HSnCl3 abstraction from the PtH(SnCl3)(L) catalytic
intermediates by reductive elimination and resulted in
the formation of an ammonium salt, RNMe2 ·HSnCl3
[25]. Therefore, the expected favourable effect of the
hemilabile P–N ligands might be strongly diminished
by blocking one of the chelate donor atoms.
the strong trans-influence of the trichlorostannato lig-
and. (The chemical shift of the other phosphorus (P2)
practically remained unchanged.) Because of the low
resolution due to the low solubility of 2b neither the cis
nor the trans coupling of 117Sn and 119Sn can be ob-
served. It is worth noting that in the synthesis of 2b
two-fold excess of tin(II)chloride was needed to accom-
plish the insertion reaction. This fact is probably due to
the coordination of tin(II)chloride to the noncoordi-
nated N-arm.
2.2. Hydroformylation of styrene with platinum- and
rhodium-containing catalysts
Styrene (3) as model substrate was reacted in the
presence of in situ catalysts (prepared either from
rhodium containing precursor ([Rh(nbd)Cl]2) and lig-
ands 1 or 2, or platinum containing precursor (PtCl2(1)
or PtCl2(2)) and anhydrous tin(II)chloride) with CO/H2
(1/1) at 60–100°C, under a pressure of 80 bar (Table 2).
CO/H
2
PhCHꢀCH260−100 CPhCH(CH3)CHO+Ph(CH2)2CHO
“
o
+PhC2H5
(1)
The catalytic activities of the rhodium-1 and
rhodium-2 in situ systems are much higher than those
observed for 1a-SnCl2 and 2a-SnCl2 catalysts. The
rhodium- and platinum-containing catalytic systems
yielded strikingly different product distributions. Both
chemo- and regioselectivity towards branched aldehyde
(4) are much higher when rhodium-containing systems
are used. The formation of hydrogenated product (6) is
almost negligible in this case. The ee-s obtained with
both rhodium and platinum catalysts are extremely
low.
However, enantioselectivity could be slightly in-
creased by the addition of bdpp ((2S,3S)-2,4-bis(-
diphenylphosphino)pentane). The higher activity
observed in this case shows the interplay of ferrocene-
type ligands and bdpp. The absolute configuration of
the predominating enantiomer of 4 was found to be R
when the 1b-(2S,4S)bdpp-SnCl2 system was applied.
The ee-s are undoubtedly higher than those obtained
Catalyst precursors prepared in situ from complex
PdCl2(1) and ligand 1 or complex (PdCl2)3(2)2 and
ligand 2 have been tested in hydromethoxycarbonyla-
tion of styrene (Eq. 2).
CO/CH OHPhCH(CH3)COOCH3
3
PhCH(CH2
“
+Ph(CH2)2COOCH3
(2)
In all cases both regioisomers were formed but the
regioselectivities are completely different depending on
the two catalytic precursors used (Table 2). While in the

40
B. Jedlicka et al. / Journal of Organometallic Chemistry 563 (1998) 37–41
Table 2
Hydroformylation and hydromethoxycarbonylation of styrene using ferrocenyl ligands, 1 and 2a
Catalyst
R. time
[h]
T
Conv.
[%]
Rcb
Rcbr
[%]
e.e.
[%]
[°C]
[%]
PtCl2(1)+SnCl2
100
30
15
80
15
14
14
180
450
80
80
100
80
90
60
60
110
110
89
79
90
49
98
38
76
100
50
74
93
83
88
88
99
99
71
100
58
32
60
51
33
94
89
—
28
n.a.
PtCl2(1)+bdpp+SnCl2
PtCl2(1)+bdpp+SnCl2
PtCl2(2)+SnCl2
PtCl2(2)+bdpp+SnCl2
[Rh(nbd)Cl]2+1
[Rh(nbd)Cl]2+2
PdCl2(1)+1
(PdCl2)3(2)2+2
21 (S)
7 (S)
3 (S)
7 (R)
0.5 (R)
2 (S)
—
a Reaction conditions: 0.025 mmol PtCl2(1igand); 0.05 mmol SnCl2; 30 ml toluene; 100 mmol styrene; p(CO)=p(H2)=40 bar (in hydroformyla-
tion) 0.04 mmol PdCl2(1igand); 0.02 mmol ligand; 16 mmol styrene, 10 ml toluene; 5 ml methanol; 130 bar CO (in hydromethoxycarbonylation).
b (4+5)/(4+5+6)×100 (for hydroformylation).
c 4/(4+5)×100 (for hydroformylation); 7/(7+8)×100 (for hydromethoxycarbonylation).
3.1. Synthesis of PtCl2(1) (1a) and PtCl2(2) (2a)
presence of 1 the branched regioisomer (7) predomi-
nates, the application of ligand 2 resulted in the forma-
tion of the linear ester (8) as the main product. The
results are similar to those obtained with monodentate
and bidentate phosphines, respectively. Although in the
trinuclear catalytic precursor, 2c ((PdCl2)3(2)2 [20,21])
two of the palladium atoms contain P–N coordinated
ligands and the third one shows trans-monodentate
type coordination, upon addition of the free ligand (2),
the PP bidentate coordination can not be excluded
under catalytic conditions.
As a conclusion it can be stated, that the rather rigid
ferrocenyl ligands possessing a relatively small bite
angle (especially when bound to platinum) are not
sufficiently active in carbonylation reactions. A system-
atic investigation of the influence of ferrocenyl ligand
structure on carbonylation activity is in progress.
A 0.2 mmol amount of PtCl2(PhCN)2 was dissolved
in 16 ml refluxing benzene, and a solution of 0.2 mmol
1 (or 2) in 4 ml of benzene was added. The experiment
was conducted for 2 h. A dark yellow solid was formed,
which was filtered off after the mixture was cooled to
r.t.. The product was washed with cold benzene. The
yields were 90 and 80% for 1a and 2a, respectively.
1a: 1H-NMR (CDCl3, 300 MHz, TMS): (selected
data) 3.45 (s with broad Pt satellites, J(Pt,CH3)=26
Hz; 3H, NCH3); 3.68 (s with broad Pt satellites,
J(Pt,CH3)=30 Hz, 3H, NCH3); 3.85 (t, J=4 Hz, 1H,
Cp-H); 4.22 (s, 5H, Cp); 4.58 (d, J=4 Hz, 1H, Cp-H);
31P-NMR (CDCl3, 121.4 MHz, H3PO4): see Table 1.
Analysis calculated for C28H30NPCl2FePt (M=733.36):
C, 45.86; H, 4.12; N, 1.91; Found: C, 45.98; H, 4.31; N,
2.05%; yield: 90%.
2a: 1H-NMR (CDCl3, 300 MHz, TMS): (selected
data) 1.90 (s, 6H, N(CH3)2); 3.82 (m, 1H, Cp-H); 4.20
(m, 1H, Cp); 4.35 (m, 2H, Cp-H); 4.55 (m, 1H, Cp-H);
4.60 (m, 1H, Cp-H); 31P-NMR (CDCl3, 121.4 MHz,
H3PO4): see Table 1. Analysis calculated for
C40H39NP2Cl2FePt (M=917.54): C, 52.36; H, 4.28; N,
1.53; Found: C, 52.44; H, 4.42; N, 1.70; yield: 80%.
3. Experimental
The
catalytic
precursors
PtCl2(PhCN)2,
PdCl2(PhCN)2 and [Rh(nbd)Cl]2 were prepared as de-
scribed previously [26,27]. Toluene was distilled under
argon from sodium in the presence of benzophenone.
Styrene was freshly distilled before use. Anhydrous
tin(II)chloride
was
prepared
by
dehydrating
3.2. Hydroformylation experiments
SnCl2 ·2H2O with a stoichiometric amount of acetic
anhydride, followed by washing with dry diethyl ether.
The 1H- and 31P-NMR spectra were recorded in
CDCl3 on a Varian Unity 300 spectrometer at 300 and
121.4, MHz, respectively. The chemical shifts were re-
ported relative to tetramethylsilane and H3PO4, respec-
tively. The samples were analysed with a Hewlett
Packard 5830A gas chromatograph fitted with a capil-
lary column coated with OV-1. The elemental analyses
were performed on a 1108 Carlo Erba apparatus.
In a typical experiment a solution of 0.025 mmol of
PtCl2(1) and 0.05 mmol of SnCl2 in 30 ml toluene
containing 0.1 mol of styrene was transferred under
argon into a 150 ml stainless steel autoclave. The
reaction vessel was pressurised to 80 bar total pressure
(CO/H2=1/1) and placed in an oil bath and the mix-
ture stirred with a magnetic stirrer. The pressure was
monitored throughout the reaction. After cooling and
venting of the autoclave, the pale yellow solution was

B. Jedlicka et al. / Journal of Organometallic Chemistry 563 (1998) 37–41
41
[5] S. Gladiali, J.C. Bayo´n, C. Claver, Tetrahedron Asymmetry 6
(1996) 1453.
[6] G. Consiglio, P. Pino, L.I. Flowers, C.U. Pittmann Jr., J. Chem.
Soc. Chem. Commun. (1983) 612.
removed and immediately analysed by GC. After a
fractional distillation the specific rotation of the 2-
phenylpropanal fraction was measured.
[7] P. Haelg, G. Consiglio, P. Pino, J. Organomet. Chem. 296 (1985)
281.
3.3. Hydromethoxycarbonylation experiments
[8] G. Consiglio, F. Morandini, M. Scalone, P. Pino, J. Organomet.
Chem. 279 (1985) 193.
[9] L. Kolla´r, G. Consiglio, P. Pino, J. Organomet. Chem. 330
(1987) 305.
[10] L. Kolla´r, J. Bakos, I. Toth, B. Heil, J. Organomet. Chem. 350
(1988) 277.
[11] G. Consiglio, S. C. A. Nefkens, A. Borer, Organometallics 10
(1991) 2046.
[12] I. To´th, I. Guo, B. Hanson, Organometallics 12 (1993) 848.
[13] G. Parrinello, J.K. Stille, J. Am. Chem. Soc. 109 (1987) 7122.
[14] N. Sakai, S. Mano, K. Nozaki, H. Takaya, J. Am. Chem. Soc.
115 (1993) 7033.
[15] N. Sakai, K. Nozaki, H. Takaya, J. Chem. Soc. Chem. Com-
mun. (1994) 395.
In a typical experiment 0.04 mmol of PdCl2(1) and
0.02 mmol of 1 was measured into a 150 ml stainless
steel autoclave and charged with 1.8 ml styrene, 10 ml
toluene and 5 ml methanol under argon atmosphere.
The reaction vessel was pressurised to 130 bar CO
pressure and placed in an oil bath and the mixture
stirred magnetically. The pressure was monitored
throughout the reaction. After cooling and venting of
the autoclave, the dark red solution was removed and
immediately analysed by GC.
[16] A. Togni, T. Hayashi (Eds.), Ferrocenes, VCH, Weinheim, 1995.
[17] H. Brunner, W. Zettlmeier, Handbook of Enantioselective Catal-
ysis with Transition Metal Compounds, VCH, Weinheim, 1993.
[18] B. Jedlicka, C. Kratky, W. Weissensteiner, M. Widhalm, J.
Chem. Soc. Chem. Commun. (1993) 1329.
Acknowledgements
The authors thank the Hungarian National Science
8
[19] H. Wally, K. Schlo¨gl, W. Weissensteiner, M. Widhalm, Tetrahe-
dron Asymmetry 4 (1993) 285.
Foundation and Stiftung Aktion Osterreich–Ungarn
for financial support (grants OTKA T023525 and 26u2,
respectively).
[20] B. Jedlicka, PhD. Thesis, University of Vienna, Austria, 1995.
[21] B. Jedlicka, R.E. Ru¨lke, W. Weissensteiner, R. Fernandez-
Gala´n, F.A. Jalo´n, B.R. Manzano, J. Rodriguez-de-la Fuente,
N. Veldman, H. Kooijman, A.L. Spek, J. Organomet. Chem. 516
(1996) 97.
References
[22] G. Consiglio, J. Organomet. Chem. 132 (1977) 26.
[23] S. Toˆro¨s, B. Heil, L. Marko´, J. Organomet. Chem. 159 (1978)
401.
[24] L. Kolla´r, J. Bakos, I. To´th, B. Heil, J. Organomet. Chem. 370
(1989) 257.
[25] L. Kolla´r, G. Szalontai, P. Sa´ndor, B. Heil, J. Organomet. Chem
393 (1990) 153.
[26] F.R. Hartley, Organomet. Chem. Rev. A 6 (1970) 119.
[27] E.W. Abel, M.A. Bennett, G. Wilkinson, J. Chem. Soc. (1959)
3178.
[1] H.M. Colquhoun, D.J. Thompson, M.V. Twigg, Carbonylation.
Direct Synthesis of Carbonyl Compounds, Plenum Press, New
York and London, 1991.
[2] B. Cornils, in: J. Falbe (Ed.), New Synthesis with Carbon
Monoxide, Springer Verlag, Berlin, 1980, p. 133.
[3] M. Beller, B. Cornils, C.D. Frohning, C.W. Kohlpaintner, J.
Mol. Catal. A 104 (1995) 17.
[4] C. Botteghi, S. Paganelli, A. Schionato, M. Marchetti, Chirality
3 (1991) 355.
.