Platinum(II) complexes incorporating racemic and optically active 1-alkyl-3-phospholenes and 1-propyl-phospholane P-ligands: Synthesis, stereostructure, NMR properties and catalytic activity

Article abstract of DOI:10.1016/j.jorganchem.2011.08.006

Racemic and optically active 1-propyl- and 1-butyl-3-methyl-3-phospholene oxides, as well as 1-propyl-3-methylphospholane oxides were converted after deoxygenation to the corresponding phosphine-borane and phopshine-platinum complexes. Stereostructure of the novel platinum complexes with a propyl group on the phosphorus atom was evaluated by quantum chemical calculations. The complexes displayed characteristic properties regarding their NMR spectra and showed unusual regioselectivity as catalysts in the hydroformylation of styrene derivatives. Ee-s up to 21% were obtained in the presence of optically active Pt-complex precursors.

Full text of DOI:10.1016/j.jorganchem.2011.08.006

Journal of Organometallic Chemistry 696 (2011) 3557e3563
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Platinum(II) complexes incorporating racemic and optically active 1-alkyl-3-
phospholenes and 1-propyl-phospholane P-ligands: Synthesis, stereostructure,
NMR properties and catalytic activity
,
a
b
c
d
d
György Keglevicha , Péter Bagi , Áron Szöllosy , Tamás Körtvélyesi , Péter Pongrácz , László Kollár ,
*
}
László Drahose
a Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 1521 Budapest, Hungary
b Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, 1521 Budapest, Hungary
c Department of Physical Chemistry and Material Science, University of Szeged, H-6701 Szeged, Hungary
d Department of Inorganic Chemistry, University of Pécs, 7624 Pécs, Hungary
e Hungarian Academy of Sciences, Chemical Research Center, 1525 Budapest, Hungary
a r t i c l e i n f o
a b s t r a c t
Article history:
Racemic and optically active 1-propyl- and 1-butyl-3-methyl-3-phospholene oxides, as well as 1-propyl-
3-methylphospholane oxides were converted after deoxygenation to the corresponding phosphine-
borane and phopshine-platinum complexes. Stereostructure of the novel platinum complexes with
a propyl group on the phosphorus atom was evaluated by quantum chemical calculations. The complexes
displayed characteristic properties regarding their NMR spectra and showed unusual regioselectivity as
catalysts in the hydroformylation of styrene derivatives. Ee-s up to 21% were obtained in the presence of
optically active Pt-complex precursors.
Received 8 July 2011
Received in revised form
5 August 2011
Accepted 12 August 2011
Keywords:
3-Phospholene
Phospholane
Ó 2011 Elsevier B.V. All rights reserved.
Borane complex
Platinum complex
Stereostructure
Catalyst precursor
Hydroformylation
1. Introduction
P-ligands, DuPhos [13], PennPhos [14] and BIPNOR [15] are to be
mentioned, but only DuPhos has been applied in platinum
Transition metal complexes incorporating P(III)-ligands are of
increasing importance due to their applicability as catalysts in
homogeneous catalytic processes [1,2]. Platinum complexes, due to
their high thermodynamic stability and kinetic inertness, form
perhaps the best-studied field within transition metal chemistry.
Regarding platinum complexes, the species with P-heterocyclic
ligands represent a dynamically developing field [3e5]. Arylphosp-
holes, 3-phospholenes, phospholanes, a 1,4-dihydrophosphinine
and a 1,2,3,6-tetrahydrophosphinine were converted to the corre-
sponding platinum complexes by Kollár and Keglevich [6e9]. Pringle
et al. described the platinum complexes of a few phospholanes,
phosphinines and phosphepanes [10], as well as those of
9-phosphabicyclononanes (Phobanes) [11] and 6-phospha-2,4,8-
trioxaadamantanes [12]. Among the bidentate heterocyclic
complexes [16e18]. 3-Diphenylphosphino-1,2,3,6-tetrahydropo-
sphinine and 3-diphenylphosphino-1,2,3,4,5,6-hexahydrophosphin-
ine served as bidentate P-ligands to form the corresponding cis
chelate platinum complexes [19e22]. Recently, P-aryl, P-amino and
P-alkoxy dibenzo[c.e][1,2]oxaphosphorines including optically active
derivatives were synthesized by us and were converted to the cor-
responding bis(dibenzooxaphosphorino)dichloro-platinum compl-
exes or related species [23e28]. These complexes incorporated
mainly phosphinites, phosphonites and phosphonous amides as
P(III)-ligands.
Recently, we were successful in resolving the racemates of aryl-,
alkyl- and alkoxy-3-phopholene oxides [29e33] that are potential
precursors of heterocyclic P-ligands. On the one hand, TADDOL
derivatives were utilized via (diastereomeric) molecular complexes
[29,30], on the other hand, the calcium salts of dibenzoyl tartaric
acid derivatives were applied to form inclusive coordination
complexes [31,32].
* Corresponding author. Tel.: þ36 1 4631111/5883; fax: þ36 1 4633648.
E-mail address: gkeglevich@mail.bme.hu (G. Keglevich).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.08.006

3558
G. Keglevich et al. / Journal of Organometallic Chemistry 696 (2011) 3557e3563
In this paper, novel platinum complexes with racemic and
optically active 1-propyl- and 1-butyl-3-phospholene and 1-
propyl-phospholane P-ligands are synthesized, characterized and
tested as catalysts in hydroformylation.
2. Results and discussion
2.1. Synthesis and structure of heterocyclic borane and platinum
complexes
First, the 1-propyl- and 1-butyl-3-methyl-3-phospholene
oxides (1a and 1b) were synthesized [33] and the racemates were
separated into the optically active forms using (R,R)-TADDOL and
(R,R)-spiro-TADDOL as the resolving agent [30]. For the butyl-
phospholene oxide (1b), this is the first case that one of the
enantiomers was made available. The (S)-1a and (R)-1a enantio-
mers were obtained in an ee of 92% and 95%, respectively, while one
of the two enantiomers of 1b was prepared in an ee of 93%.
Assuming an analogy with the case of propyl-phospholene oxide
(1a), the negative sign of the optical rotation of the isolated enan-
tiomer may refer to the (S) form of 1b (Scheme 1).
Then the racemic and optically active forms (1a, b and (S)-1a, b,
respectively) were subjected to deoxygenation with trichlorosilane
[34] to afford the phosphines (2a, b and (R)-2a, b, respectively).
Phosphines 2a and (R)-2a were reacted with dimethylsulfide-
borane, resulting in the formation of phosphine-boranes 3a and
(R)-3a, respectively (Scheme 2). The phosphine-boranes can be
regarded as protected phosphines from which the P(III) form can
be liberated by reaction with a secondary amine (e.g. diethylamine)
on heating in an apolar solvent [35]. 3-Phospholenes 2a, b and
(R)-2a, b were then converted to the corresponding platinum
complexes 4a and 4b by reaction with dichlorodibenzonitrile
platinum at 26 ꢀC, using benzene as the solvent. Starting from the
racemic phosphines (2a, b), complex 4a, b was formed as a 1:1
mixture of the homochiral (R,R- and S,S) and the heterochiral (R,S)
forms. At the same time, the complex formation of the (R)-2a,
b phosphine with platinum provided the optically active (S, S)-4a,
b product (Scheme 3).
Scheme 2.
splittings. The J(195Pte13C) and J(31Pe13C) coupling constants were
determined by first-order analysis of these splittings for complex
4a, see (Fig. 1).
Stereostructure of the S,S-isomer of complex 4a was calculated
by the B3LYP/6-31G** þ LANL2DZ methods. The most stable
structure of complex (S,S)-4a can be seen in Fig. 2. The molecule is
symmetrical. A weak interaction can be assumed between the
C(3)eC(4) double bond of the heterocyclic moiety and the C(20)H2
group of the propyl group of the other hetero ring.
Next, the racemic and optically active ((R)-) forms of
3-phospholene oxide 1a were subjected to catalytic hydrogenation
to afford phospholane oxide 5 as a 1:1 mixture of two diastereo-
mers. From racemic 1a, product 5 was also formed as racemates,
while from optically active (R)-1a, 5 was obtained as a mixture of
the optically active (RPRC)- and (RPSC)- forms (Scheme 4).
The diastereomeric mixtures of the racemic and optically active
((R)-) phospholane oxides 5 were then reduced by trichlorosilane
to give the corresponding (racemic or optically active) forms of the
phospholane 6, or after reaction with borane, the phosphine-
borane 7. Assuming retention during the reduction, the absolute
configuration of the phosphorus atom in the optically active forms
of the phospholane (6) and phospholane-borane (7) is S in both
cases (Scheme 5).
The platinum complexes 4a, b were characterized by 31P, 13C and
1H NMR spectrometry, as well as by HRMS. According to expecta-
tion [5], the complexes 4a, b exhibited the P-donor atoms in cis
position. This was justified by the J(31Pe195Pt) couplings of
3421e3451 Hz obtained from the 31P NMR spectra, indicating that
both phosphorus atoms have chloro ligands in the trans position
[5]. The platinum complexes 4a, b exist as a mixture of isotopomers
due to the different Pt isotopes in natural abundance. The isotope
shifts have practically no significance in the 13C NMR spectra,
however, the 195Pt nucleus with 1/2 nuclear spin and 33.8% natural
abundance resulted in a complex signal structure, considering also
that most of the signals are affected by two further and different 31P
Phospholanes 6 and (S)-6 were then reacted with the platinum
precursor at ambient temperature in benzene. Reaction of the
racemic phospholane (6) led to an 8:22:32:13:10:15 mixture of six
isomers (from among four were racemates) as shown in Scheme 6.
At the same time, the complex forming reaction of the
Me
R
Me
R
26 °C
PtCl2(PhCN)2
2
(1)
P
P
PhH
Pt
Cl
Cl
(R,R)-4 (S,S)-4 (homochiral forms)
(R,S)-4 (heterochiral forms)
R"
1.)
R'
O
O
Ph
Ph
Ph
Ph
Me
R
Me
R
Me
R
Me
Me
R
26 °C
OH HO
4
5
3
2
PtCl2(PhCN)2
+
P
P
P
1
(R)-2
2.) filtration
(2)
P
P
O
O
O
PhH
3.) recrystallization
4.) chromatography
R
Pt
1
(R)-1
(S)-1
Cl
Cl
(S,S)-4
Me, Me
R
(R)-1 [% ee] (S)-1
R', R" =
Pr (a)
Bu (b)
95
92
93
R = Pr (a), Bu (b)
Scheme 1. [30].
Scheme 3.

G. Keglevich et al. / Journal of Organometallic Chemistry 696 (2011) 3557e3563
3559
Fig. 1. The 13C NMR spectral assignment for complex (S,S)-4a.
Scheme 4.
(6), a second set of similar signals appears with quite similar
diastereomeric mixture of phospholane (S)-6 afforded a 23:45:32
mixture of isomers (RPRC,RPRC)-8, (RPSC,RPRC)-8 and (RPSC,RPSC)-8
(Scheme 6).
intensity ratios. Each phosphorus signals shows the respective 195Pt
satellites with a 1
J
coupling constant of ca. 3447 Hz.
Pt-P
The platinum complexes were characterized by 31P and 13C
NMR, as well as by HRMS. 31P NMR spectrum of the mixture of the
phospholaneeplatinum complex 8 prepared from the 1:1 mixture
of the (SPRC) and (SPSC) phospholanes is shown in Fig. 3. The
spectrum contains two singlets, as well as an AB system. Diaste-
reomers (RPRC,RPRC)-8 and (RPSC,RPSC)-8 have either a symmetry
plane or an inversion center, so that their phosphorus atoms are
chemically equivalent and each compound gave only one signal. At
the same time, (RPSC,RPRC)-8 does not have any symmetry element,
so the two phosphorus atoms result in the appearance of two
signals in the spectrum coupled with each other, forming an AB
system with a JP-P coupling constant of ca. 17 Hz. In the 31P NMR
spectrum of the reaction mixture from the racemic phospholane
Stereostructure of the (RPSC,RPRC)-isomer of cis complex 8 was
evaluated by the B3LYP/6-31G** þ LANL2DZ calculations. The best
structure is shown in Fig. 4. Due to a steric interaction, the
conformation of the P-propyl group is affected by the C5-methyl
group of the phospholane moiety. The P-propyl groups are against
the C5-methyl substituents of the hetero rings.
2.2. Catalytic activity of the heterocyclic platinum complexes
synthesized
The PtCl2P2-type complexes, cis-[bis(1-alkyl-3-methyl-3-
phospholeno)-dichloro-platinum(II)] 4a and 4b, as well as cis-
[bis(1-n-propyl-3-methyl-phospholano)-dichloro-platinum(II)]
8
were tested as catalyst precursor in the hydroformylation of styrene
and its 4-substituted derivatives. The catalysts formed in situ from
4a, b or 8 and two equivalents of tin(II) chloride under standard
‘oxo-conditions’ [p(CO) ¼ p(H2) ¼ 40 bar, 100 ꢀC] were used. As
generally observed, in addition to the two types of formyl
regioisomers, 2-aryl-propanal derivatives (A) and 3-aryl-propanal
derivatives (B), the corresponding ethylbenzenes (C) as hydroge-
nation by-products were also formed (Eq. 1).
CO=H2
!
ArCHðCHOÞCH3 þArCH2CH2CHOþArCH2CH3
ArCH]CH2
B
C
A
Ar ¼ C6H5; 4ꢁCH3 ꢁC6H4; 4ꢁAcOꢁC6H4; 4ꢁClꢁC6H4
(1)
Based on the results obtained with similar catalysts containing
P-phenyl-phospholenes and phospholanes [36], the pressure of
80 bar (CO/H2 1/1) and temperature range of 60 ꢀC to 100 ꢀC was
Fig. 2. Perspective view of cis-bis(1-propyl-3-methyl-3-phospholeno)-dichloro-plati-
num(II) ((S,S)-4a) calculated by the B3LYP/6-31G** and LANL2DZ (Pt) method. The
optimized geometries (in Å and degree): PteCl 2.425, PteP 2.289, PeC2 1.869, C2eC3
1.519, C3eC4 1.340, C4eC5 1.506, PeC5 1.861, PeC10 1.848, C10eC20 1.535, C20eC30
1.533; ClePteCl 91.5, ClePteP 82.3, PtePeC2 123.3, PtePeC5 115.5, PtePeC10 112.9,
PeC2eC3 105.1, C2eC3eC4 115.8, C3eC4eC5 118.5; ClePtePeC2 165.5, PtePeC10eC20
e59.7, ClePtePeC2 165.5, PtePeC2eC3 e138.2, PeC2eC3eC4 11.2, C2eC3eC4eC5
e0.5, PeC10eC20eC30 178.9.
Scheme 5.

3560
G. Keglevich et al. / Journal of Organometallic Chemistry 696 (2011) 3557e3563
The formation of the aldehydes (A, B) was preferred in all cases
Me
nPr
Me
nPr
26 °C
and the chemoselectivity towards aldehydes typically varied in the
range of 76 and 91% using complex 4a as the precursor and styrene
as the substrate (entries 1e4) (Table 1). The application of
precursor 4b with butyl-phospholene ligands instead of the
propyl-substituted species 4a resulted in quite similar chemo-
selectivities (compare entries 1 and 9 or 2 and 10/11). Considering
also the substituted styrenes, the chemoselectivity fall in the range
of 67e93% (entries 5e8). Using the phospholano-substituted
precursor 8, the chemoselectivity was around 90% (entries
12e14). Unexpectedly, lower aldehyde selectivity was obtained
allowing a prolonged reaction time with precursor 4a (entries 2
and 3). At the same time, the ratio of the aldehydes to the
hydrogenated product was not dependent on the reaction time
using 8 as the catalytic precursor (entries 12e14).
As regards the regioselectivity, the branched aldehyde pre-
dominated in all cases. In our case, regioselectivities of 66e77%
towards the branched aldehyde were obtained in the presence of
complex 4a (entries 1e8). The use of the 4b instead of 4a resulted in
similar regioselectivities (compare entries 1 and 9 or 2 and 10/11).
At the same time, a slight decrease in the branched selectivity was
observed with 8 (entries 12e14). Practically, no influence of the 4-
substituent on the regioselectivity has been detected in the case of
complex 4a (entries 3e8). In these cases, the regioselectivities were
close to 70%.
PtCl2(PhCN)2
6
(1)
P
P
PhH
Pt
Cl
(R R ,R R )-8 (S S ,S S )-8 (8%)a
Cl
P
C
P
C
P
C
P C
(R S ,R S )-8 (S R ,S R )-8 (22%)a
P
C
P
C
P
C
P C
(R S ,R R )-8 (S R ,S S )-8 (32%)
P
C
P
C
P
C
P C
(R R ,S R )-8 (S S ,R S )-8 (13%)
P
C
P
C
P
C
P C
(S R ,R S )-8
(10%)b
(15%)b
P
C
P C
(R R ,S S )-8
P
C
P C
a,bmay be reversed, respectively
Me
Me
26 °C
PtCl2(PhCN)2
4
3
2
5
1
(S)-6
(2)
P
P
PhH
nPr
nPr
Pt
Cl
Cl
(R R ,R R )-8 (23)*
P
C
P C
(R S ,R R )-8 (45)
P
C
P C
(R S ,R S )-8 (32)*
*mayCbe Preversed
P
C
Scheme 6.
chosen. It is worth noting that low catalytic activity below 50 ꢀC
and some reduction of Pt(II) to Pt(0), i.e., the formation of some
platinum black can be observed above 125 ꢀC using the catalytic
precursors 4a and 4b or 8. Similarly, negligible conversions were
obtained below 50 bar.
Comparing these regioselectivities with the analogous
1-phenyl-3-phospholene-based ligands [36], undoubtedly higher
regioselectivities towards the branched aldehyde have been
obtained with the newly tested n-alkyl analogons. It has to be
Fig. 3. Assignment for the 31P NMR spectrum for the mixture of complexes (RPRC,RPRC)-, (RPSC,RPRC) and (RPSC,RPSC)-8.

G. Keglevich et al. / Journal of Organometallic Chemistry 696 (2011) 3557e3563
3561
added that in general, unlike the rhodium-catalyzed hydro-
formylation, the proportions of the linear and branched aldehyde
are comparable in the presence of platinum phosphine catalysts.
The prevailing formation of the linear aldehyde was observed
mostly with the most active catalysts containing bidentate ligands
[4]. Our new Pt(II) complexes described in this paper may have
relevance as catalyst precursors in the hydroformylation of other
styrene derivatives as well (see eg. the synthesis of Ibuprofen and
Naproxen), where the formation the branched aldehydes is
required.
The catalytic precursors (4a, 4b and 8) were isolated containing
the corresponding optically active 1-alkyl-phospholene-based
ligand. Their application in hydroformylation resulted in optical
inductions of 21%, 7% and 6.5/19% with 4a, 4b and 8 as the catalytic
precursors, respectively (entries 4, 11 and 13/14). It is worth noting
that, to the best of our knowledge, enantiomeric excesses of about
20% are unprecedented using monodentate phospholane and
phospholene ligands in enantioselective hydroformylation.
Furthermore, the low ee-s obtained with 8 can be substantially
improved when enantiomerically pure (e.g. (SPRC,SPRC)-8) was used
instead of the rather complicated mixture of stereoisomers (entries
13 and 14).
In summary, novel PtCl2(L)2 complexes with 1-alkyl-
substituted 3-methyl-3-phospholene and 3-methyl-phospholane
ligands were prepared and characterized. The stereostructure of
the Pt(II) complex with propyl-phospholene ligands was evalu-
ated by B3LYP/6-31G** and LANL2DZ (Pt) calculations. The Pt(II)
complex precursors proved to be catalytically active in the
hydroformylation of styrenes and displayed an interesting regio-
selectivity. With the application of the ligands in optically active
form, enantioselective hydroformylation with ee-s up to 21% can
be achieved that, compared to literature data, can be regarded to
be significant.
Fig. 4. Perspective view of cis-bis(1-propyl-3-methylphospholano)-dichloro-plati-
num(II) (RPSC,RPRC)-8 calculated by the B3LYP/6-31G** and LANL2DZ method. The
optimized geometries (in Å and degree): PteCl 2.419, 2.419, PteP 2.297, 2.298, PeC2
1.874, 1.869, C2eC3 1.547, 1.545, C3eC4 1.540, 1.541, C4eC5 1.537, 1.539, PeC5 1.861,
1.867, PeC10 1.856, 1.856, C10eC20 1.536, 1.536, C20eC30 1.533, 1.533; ClePteCl 89.6,
ClePteP 85.4, 85.9, PtePeC2 120.2, 119.6, PtePeC5 117.0, 117.1, PtePeC10 113.9, 113.8,
PeC2eC3 106.5, 106.3, C2eC3eC4 105.8, 106.5, C3eC4eC5 107.6, 108.4; ClePtePeC2
e147.2, e151.7, PtePeC10eC20 e47.9, e59.3, ClePtePeC2 e151.7, e147.2, PtePeC2eC3
114.4, 140.2, PeC2eC3eC4 34.1, e38.2, C2eC3eC4eC5 e48.6, 48.3, P-C10-C20-C30
e179.5, 178.9.
3. Experimental
3.1. General (instruments)
Table 1
The 31P, 13C, 1H NMR spectra were taken on a Bruker AV-300 or
DRX-500 spectrometer operating at 121.5, 75.5 and 300 or 202.4,
125.7 and 500 MHz, respectively. The couplings are given in Hz.
Mass spectrometry was performed on a ZAB-2SEQ instrument.
Hydroformylation of styrene and its 4-substituted derivatives (ArCH]CH2) in the
presence of in situ catalysts formed from PtCl2(1-n-Pr-3-Me-3-phospholene)2 (4a)/
PtCl2(1-n-Bu-3-Me-3-phospholene)2 (4b)/PtCl2(1-nPr-3-Me-phospholane)2 (8) and
tin(II)-chloridea.
b
c
Entry
Complex
Substrate
(Ar)
Temp.
[ꢀC]
R. time
[h]
Conv.
[%]
Rc
Rbr
[%]
[%]
3.1.1. Preparation of the enantiomers of 1-propyl-3-methyl-3-
phospholene-1-oxide (1a)
1
2
3
4
5
6
7
8
4a
4a
4a
4a
4a
4a
4a
4a
4b
4b
4b
8
C6H5
C6H5
C6H5
C6H5
4-CH3-C6H4
4-Cl-C6H4
4-AcO-C6H4
4-AcO-C6H4
C6H5
C6H5
C6H5
C6H5
C6H5
60
100
100
100
100
100
100
100
60
100
100
100
100
100
110
24
48
48
48
48
24
48
72
24
24
24
48
96
24
48
79
84
65
63
58
90
33
54
55
27
59
87
85
86
76
91
89
93
87
67
87
85
90
89
90
90
77
68
The enantiomers of 1-propyl-3-methyl-3-phospholene-1-oxide
(1) [33] were prepared as described earlier by resolution with
(R,R)-TADDOL and (R,R)-spiro-TADDOL [30]. Yield of (S)-1a: 60%;
75
69d
72
66
70
31P NMR (CDCl3)
d
76.8; ½a 2D5
ꢂ
¼ ꢁ13:3 (c 0.6, CHCl3); ee: 92%; (31
P
NMR (CDCl3)
d
76.4; ½a 2D5
¼ ꢁ13:9 [30] (c 1, CHCl3); ee: 96%). Yield
ꢂ
71
of (R)-1a: 38%; 31P NMR (CDCl3)
d
76.8; ½a 2D5
¼ þ13:4 (c 1, CHCl3);
ꢂ
9
76e
72
ee: 95% (31P NMR (CDCl3)
ee: 95%).
d
76.4; ½a 2D5
¼ þ13:4 [30] (c 1, CHCl3);
ꢂ
10
11
12
13
14
70f
65
8
8
65g
65h
3.1.2. Preparation of (S)-1-butyl-3-methyl-3-phospholene-1-oxide
((S)-1b)
(S)-1-butyl-3-methyl-3-phospholene-1-oxide ((S)-1b) [33] was
prepared analogously, but using (R,R)-spiro-TADDOL as the
C6H5
a
Reaction conditions: Pt/SnCl2/styrene ¼ 1/2/100, p(CO) ¼ p(H2) ¼ 40 bar,
1 mmol of substrate, solvent: 10 mL of toluene.
b
Chemoselectivity towards aldehydes (A, B). [(moles of A D moles of B)/(moles of
resolving agent. (1). Yield: 33%; ½a D25
ꢂ
¼ ꢁ15:2 (c 2.4, CHCl3); ee:
A þ moles of B D moles of C) ꢃ 100].
93%; 31P NMR (CDCl3)
d
69.3; 13C NMR (CDCl3)
d
13.6 (C4 ), 20.3
c
0
Regioselectivity towards branched aldehyde (A). [moles of A/(moles of
(3JPeC ¼ 10.4, C3-CH3), 24.0 (2JPeC ¼ 1.2, C2 ), 24.1 ( JPeC ¼ 16.7, C3 ),
3
A þ moles of B) ꢃ 100].
0
0
d
1
29.7 (1JPeC ¼ 62.9, C1 )*, 32.3 ( JPeC ¼ 62.9, C2)*, 35.5 (1JPeC ¼ 65.7,
ee ¼ 21 (S) (enantiomerically pure (S,S)-4a was used).
0
e
ee ¼ 4.5 (S) (enantiomerically pure (S,S)-4b was used).
C5)*, 120.8 (2JPeC ¼ 7.5, C4), 136.8 (2JPeC ¼ 12.3, C3), *tentative
f
ee ¼ 7.0 (S) (enantiomerically pure (S,S)-4b was used).
assignment; 1H NMR (CDCl3)
d 0.94 (t, 3H, CH2CH3), 1.46 (m, 2H,
g
ee ¼ 6.5 (S) (a 8/22/32/13/10/15 mixture of stereoisomers of 8 was used).
h
ee ¼ 19 (S) (a 23/45/32 mixture of stereoisomers of 8 was used).
CH2CH3), 1.62 (m, 2H, CH2CH2CH3), 1.79 (bs, 3H, C3-CH3), 1.87 (m,

3562
G. Keglevich et al. / Journal of Organometallic Chemistry 696 (2011) 3557e3563
2H, PCH2), 2.30e2.65 (m, 4H, C(2)H2 and C(5)H2), 5.49 (d, J ¼ 29.5,
1H, CH]).
(S)-1-butyl-3-methyl-3-phospholene-1-oxide ((S)-1b) with an ee
of 93%. Yield: 63%; ½a D25
ꢂ
¼ þ7:5 (c 0.7, CHCl3); 31P NMR (CDCl3)
d
18.4 (JPteP ¼ 3451).
3.1.3. Preparation of 1-propyl-3-methyl-3-phospholene-borane (3)
Racemic 1-propyl-3-methyl-3-phospholene-borane
prepared as described earlier [34]. Yield: 20%; 31P NMR (CDCl3)
32.6 (broad) ( [34] (DMSO) 34.5).
The optically active 1-propyl-3-methyl-3-phospholene-borane
3
was
3.1.6. Preparation of 1-propyl-3-methylphospholane-1-oxide (5)
The hydrogenation of 0.40 g (2.6 mmol) of racemic 1-propyl-3-
methyl-3-phospholene-1-oxide (1) was carried out in the pres-
ence of 0.20 g of Pd/C catalyst in 30 mL of methanol at 60 ꢀC under
12 bar that led to 0.28 g (69%) of 1-propyl-3-methylphospholane-1-
oxide (5) as a 1:1 mixture of two diastereomers. 31P NMR (CDCl3)
d
d
((R)-3) was prepared analogously from (S)-1-propyl-3-methyl-3-
phospholene-1-oxide ((S)-1) with an ee of 92%. Yield of 3: 18%;
½
a 2D5
NMR (CDCl3)
ꢂ
¼ ꢁ0:5 (c ¼ 1.6, CHCl3); 31P NMR (CDCl3)
d
30.7 (broad); 13C
d
70.0 (50%) and 70.3 (50%).
Optically active 1-propyl-3-methylphospholane-1-oxides
2
15.7 (3JPeC ¼ 13.0, C3 ), 16.8 ( JPeC ¼ 1.7, C2 ), 19.1
0
0
d
(3JPeC ¼ 7.4, C3-CH3), 27.7 (1JPeC ¼ 30.3, C1 ), 30.1 ( JPeC ¼ 34.1, C5),*
((RPRC)-5 and (RPSC)-5) were prepared analogously from (R)-1-
propyl-3-methyl-3-phospholene-1-oxide ((R)-1) with an ee of
95%. Yield: 81% as a 1:1 mixture of two diastereomers;
*
1
0
33.9 (1JPeC ¼ 35.8, C2),* 121.9 (C4), 137.9 (2JPeC ¼ 2.5, C3), tentative;
*
FAB-MS m/z: [M þ NH4]þ ¼ 174.
½
a 2D5
ꢂ
¼ þ5:6 (c ¼ 3.2, CHCl3); 31P NMR (CDCl3)
d
70.5 (50%) and
70.8 (50%); 13C NMR (CDCl3)
d
15.7 (3JPeC ¼ 14.2, C3 ), 15.8
0
3.1.4. Preparation of cis-[bis(1-propyl-3-methyl-3-phospholeno)-
dichloro-platinum(II)] (4a)
(2JPeC ¼ 4.0), 15.9 (2JPeC ¼ 4.1) C2 , 21.0 (3JPeC ¼ 11.3), 21.2
0
The deoxygenation of 0.051 g (0.32 mmol) of racemic 1-propyl-
3-methyl-3-phospholene-1-oxide (1a) was carried out in benzene
according to the procedure described in Section 3.1.3. Then 0.076 g
(0.16 mmol) of dichlorodibenzonitrileplatinum in 3 mL of degassed
benzene was added to the reaction mixture under nitrogen. The
mixture was stirred at 25 ꢀC for 1 day, whereupon the complex
gradually precipitated. A separation by filtration led to 0.078 g
(88%) of crude product, that was dissolved in 2 mL of benzene and
then 4 mL of n-heptane was added. The crystals precipitated were
collected by filtration to give 0.052 g (58%) of 4a as a 1:1 mixture of
the homo- (R,R and S,S) and the heterochiral (R,S) forms. 31P NMR
(3JPeC ¼ 11.3) C3-CH3, 27.1 (1JPeC ¼ 63.8), 28.5 (1JPeC ¼ 62.7) C5,* 32.6
(2JPeC ¼ 5.5), 33.0 (2JPeC ¼ 6.8) C3, 33.3 (1JPeC ¼ 61.4), 33.5
(1JPeC ¼ 61.6) C1 , 33.5 (2JPeC ¼ 5.7), 33.6 (2JPeC ¼ 7.4) C4, 35.0
*
0
(1JPeC ¼ 65.2), 35.7 (1JPeC ¼ 64.0) C2,* *tentative assignment; 1H
NMR (CDCl3)
d 1.04 (t, 3H, CH2CH3), 1.16 (d, 3H, C3-CH3), 1.23e2.61
(m, 11H, CH2CH3, PCH2, C(2)H2, C(3)H, C(4)H2, C(5)H2); FAB-MS,
[M þ H]þ
¼ 161.1094, C8H18PO requires 161.1095.
found
3.1.7. Preparation of 1-propyl-3-methylphospholane-borane
complex (7)
Racemic 1-propyl-3-methylphospholane-1-oxide (5) was
transformed to phosphine-borane 7 analogously to the 1 /3
(DMSO)
d
18.32 (JPteP ¼ 3424, 50%) and 18.28 (JPteP ¼ 3421, 50%);
FAB-MS m/z: [M ꢁ Cl]þ ¼ 513.
conversion. Yield: 19%; 31P NMR (CDCl3)
d
32.1 (broad); 13C NMR
2
15.8 (3JPeC ¼ 13.0, C3 ), 17.2 ( JPeC ¼ 1.1), 17.3 (2JPeC ¼ 1.1)
0
The optically active cis-[bis(1-propyl-3-methyl-3-phospholeno)-
dichloro-platinum(II)] ((S,S)-4) was prepared analogously from (S)-1-
propyl-3-methyl-3-phospholene-1-oxide ((S)-1a) with an ee of 92%.
(CDCl3)
0
d
C2 , 20.3 ( JPeC ¼ 8.9), 20.5 (3JPeC ¼ 10.7) C3-CH3, 24.0 (1JPeC ¼ 35.1),
3
24.1 (1JPeC ¼ 36.0) C5,* 28.4 (1JPeC ¼ 29.7), 28.6 (1JPeC ¼ 29.6) C1 ,
*
0
Yield of (S,S)-4a: 53%; ½a D25
ꢂ
¼ þ18:7 (c ¼ 1.4, CHCl3); 31P NMR
32.0 (1JPeC ¼ 36.1), 32.3 (1JPeC ¼ 35.7) C2,* 34.7, 36.1 (C4), 35.2, 35.8
(CDCl3)
d
18.1 (JPteP ¼ 3444); 13C NMR (CDCl3)
d
15.5 (4JPteC ¼ 18.5,
(C3), *tentative assignment; 1H NMR (CDCl3)
d 1.02 (t, 3H, CH2CH3),
3
3
4
JPeC ¼ 16.0, C3 ),18.4 ( JPteC ¼ 24.8, C2 ),18.9 ( JPteC ¼ 45.0, 3JPeC ¼ 4.1,
1.09 (d, 3H, C3-CH3), 1.17e2.63 (m, 11H, CH2CH3, PCH2, C(2)H2, C(3)
0
0
5
1
3
JPeC ¼ 4.1, C3-CH3), 30.2 (2JPteC ¼ 36.3, JPeC ¼ 41.8, JPeC ¼ 7.3, C1 ),
H, C(4)H2, C(5)H2); FAB-MS, [M þ Na]þ
¼ 181.1298, C8H20PBNa
0
found
32.6 (2JPteC ¼ 58.9, JPeC ¼ 44.8, JPeC ¼ 4.8, C2), 36.3 (2JPteC ¼ 48.1,
requires 181.1293 for the 11B isotope.
1
3
1JPeC ¼ 47.8, JPeC ¼ 6.1, C5), 122.2 (3JPteC ¼ 32.0, C4), 138.8
Optically
active
1-propyl-3-methylphospholane-boranes
3
(3JPteC ¼ 32.0, JPeC ¼ 2.2, JPeC ¼ 2.2, C3); 1H NMR (CDCl3)
d
1.06 (t,
((SPRC)-7, (SPSC)-7) were prepared analogously from the 1:1 mixture
of (R,R)-, (R,S)-1-propyl-3-methylphospholane-1-oxides ((RPRC)-5,
(RPSC)-5). Yield: 19% (1:1 mixture of two diastereomers);
2
4
6H, CH2CH3),1.64 (m, 4H, CH2CH3), 1.84 (bs, 6H, C3-CH3),1.99 (m, 4H,
PCH2), 2.31 and 2.89 (AB, Jgem ¼ 18.8, 2H, C(2)H2), 2.32 and 3.02 (AB,
Jgem ¼ 18.8, 2H, C(5)H2), 5.51 (d, J ¼ 23.2, 2H, CH]); FAB-MS,
½
a 2D5
ꢂ
¼ þ74:4 (c ¼ 0.5, CHCl3); 31P NMR (CDCl3)
d 32.1 (broad);
¼ 181.1297, C8H20PBNa requires 181.1293
[M ꢁ Cl]þ
¼ 513.1146, C16H30P2ClPt requires 513.1138 for the
FAB-MS, [M þ Na]þ
found
found
35Cl and the 194Pt isotopes.
for the 11B isotope.
3.1.5. Preparation of cis-[bis(1-butyl-3-methyl-3-phospholeno)-
dichloro-platinum(II)] (4b)
3.1.8. Preparation of cis-[bis(1-propyl-3-methylphospholano)-
dichloro-platinum(II)] (8)
Racemic
1-butyl-3-methyl-3-phospholene-1-oxide
(1b)
Racemic 1-propyl-3-methylphospholane-1-oxide (5) (0.054 g
(0.34 mmol)) was transformed to complex 8 analogously to the
1 /2 / 4 conversion. Yield: 39% as a 8a:22a:32:13:10b:15b mix-
ture of (RPRC,RPRC)-8/(SPSC,SPSC)-8, (RPSC,RPSC)-8/(SPRC,SPRC)-8,
(RPSC,RPRC)-8/(SPRC,SPSC)-8, (RPRC,SPRC)-8/(SPSC,RPSC)-8, (SPRC,RPSC)-
8, (RPRC,SPSC)-8 isomers, respectively, a,b may be reversed; 31P NMR
(0.059 g (0.34 mmol)) was transformed to complex 4b analogously
to the 1 / 2 / 4 conversion. Yield: 23%; 31P NMR (CDCl3)
d 18.3
(JPteP ¼ 3451); 13C NMR (CDCl3)
d
13.6 (C4 ), 19.0 ( JPteC ¼ 34.6,
4
0
3JPeC ¼ 7.2, JPeC ¼ 4.1, C3-CH3), 24.0 (4JPteC ¼ 35.8, JPeC ¼ 7.5,
5
3
JPeC ¼ 7.5, C3 ), 26.7 (3JPteC ¼ 24.1, C2 ), 27.8 (2JPteC ¼ 37.6,
5
0
3
0
JPeC ¼ 42.2, JPeC ¼ 7.0, C1 ), 32.6 (2JPteC ¼ 53.7, JPeC ¼ 45.0,
(CDCl3)
d
18.47 (1JPteP ¼ 3445, 8%) for (RPRC,RPRC)-8 and (SPSC,SPSC)-
1
1
0
3JPeC ¼ 5.0, C2), 36.3 (2JPteC ¼ 51.4, 1JPeC ¼ 47.0, 3JPeC ¼ 4.4, C5), 122.3
8a, 17.93 (1JPteP ¼ 3446, 22%) for (RPSC,RPSC)-8 and (SPRC,SPRC)-8a,
(3JPteC ¼ 47.1, JPeC ¼ 14.9, C4), 138.8 (3JPteC ¼ 50.9, JPeC ¼ 16.0,
17.84 (1JPteP ¼ 3448, JPeP ¼ 17), 18.27 (1JPteP ¼ 3444, JPeP ¼ 17)
(32%) for (RPSC,RPRC)-8 and (SPRC,SPSC)-8, 18.05 (1JPteP ¼ 3444,
2JP,P ¼ 18) and 18.36 (1JPteP ¼ 3446, 2JPeP ¼ 18) (13%) for (RPRC,SPRC)-8
and (SPSC,RPSC)-8, 18.22 (1JPteP ¼ 3447, 10%) for (SPRC,RPSC)-8b, 17.86
2
2
2
2
4JPeC ¼ 2.2, C3); 1H NMR (CDCl3)
d 0.92 (t, 6H, CH2CH3), 1.45 (m, 4H,
CH2CH3), 1.58 (m, 4H, CH2CH2CH3), 1.84 (bs, 6H, C3-CH3), 2.00 (m,
4H, PCH2), 2.60e3.10 (m, 8H, C(2)H2 and C(5)H2), 5.50 (d, J ¼ 23.6,
2H, CH]); FAB-MS, [M ꢁ Cl]þ
¼ 541.1462, C18H34P2ClPt
(1JPteP ¼ 3447, 15%) for (RPRC,SPSC)-8b, a,b may be reversed; 13C NMR
found
requires 541.1451 for the 35Cl and the 194Pt isotopes.
(CDCl3)
d
15.6 (4JPteC ¼ 18.7, 3JPeC ¼ 15.6, C3 ),19.4 ( JPteC ¼ 23.8, C2 ),
3
0
0
The optically active cis-[bis(1-butyl-3-methyl-3-phospholeno)-
dichloro-platinum(II)] ((S,S)-4b) was prepared analogously from
20.1e20.6 (m, C3-CH3); FAB-MS, [M ꢁ Cl]þ
¼ 517.1476,
found
C16H34P2ClPt requires 517.1451 for the 35Cl and the 194Pt isotopes.

G. Keglevich et al. / Journal of Organometallic Chemistry 696 (2011) 3557e3563
3563
[6] G. Keglevich, in: O.A. Attanasi, D. Spinelli (Eds.), Targets in Heterocyclic
Systems, vol. 6, Italian Society of Chemistry, 2002, p. 245.
The optically active cis-[bis(1-propyl-3-methylphospholano)-
dichloro-platinum(II)] ((RPRC,RPRC)-, (RPSC,RPRC) and (RPSC,RPSC)-8)
was prepared analogously from the 1:1 mixture of 1-propyl-3-
methylphospholanes ((SP,RC)-6, (SP,SC)-6). Yield: 22% as a 23*:45:32*
mixture of the (RPRC,RPRC)-8*:(RPSC,RPRC)-8:(RPSC,RPSC)-8* isomers,
}
[7] Z. Csók, G. Keglevich, G. Petocz, L. Kollár, Inorg. Chem. 38 (1999) 831.
}
[8] Z. Csók, G. Keglevich, G. Petocz, L. Kollár, J. Organomet. Chem. 586 (1999) 79.
[9] A. Kerényi, V. Kovács, T. Körtvélyesi, K. Ludányi, L. Drahos, G. Keglevich,
Heteroatom Chem. 21 (2010) 63.
[10] R.A. Baber, M.F. Haddow, A.J. Middleton, A.G. Orpen, P.G. Pringle, Organo-
metallics 26 (2007) 713.
[11] M. Carreira, M. Charemsuk, M. Eberhard, N. Fey, R. van Ginkel, A. Hamilton,
W.P. Mul, A.G. Orpen, H. Phetmung, P.G. Pringle, J. Am. Chem. Soc. 131 (2009)
3078.
[12] J.H. Downing, J. Floure, K. Heslop, M.F. Haddow, J. Hopewell, M. Luisi,
H. Phetmung, A.G. Orpen, P.G. Pringle, R.I. Pugh, D. Zambrano-Williams,
Organometallics 27 (2008) 3216.
*may be reversed; ½a 2D5
ꢂ
¼ ꢁ17:3 (c ¼ 0,1, CHCl3); 31P NMR (CDCl3)
d
18.34 (1JPteP ¼ 3445, 23%) for (RPRC,RPRC)-8*, 17.69 (1JPteP ¼ 3448,
2JPeP ¼ 17), 18.17 (1JPteP ¼ 3443, JPeP ¼ 17, 45%) for (RPSC,RPRC)-8,
2
17.81 (1JPt,P ¼ 3447, 32%) for (RPSC,RPSC)-8*, *may be reversed,13C NMR
3
0
0
(CDCl3)
d
15.6 (3JPeC ¼ 15.8, C3 ),19.3 ( JPteC ¼ 24.9, C2 ), 20.1e20.5 (m,
C3-CH3); FAB-MS, [M ꢁ Cl]þ
¼ 517.1458, C16H34P2ClPt requires
found
[13] T.P. Clark, C.R. Landis, Tetrahedron: Asymmetry 15 (2004) 2123.
[14] Q. Jiang, Y. Jiang, D. Xiao, P. Cao, X. Zhang, Angew. Chem. Int. Ed. 37 (1998)
1100.
517.1451 for the 35Cl and the 194Pt isotopes.
[15] F. Robin, F. Mercier, L. Ricard, F. Mathey, M. Spagnol, Chem. A Eur. J. 3 (1997)
1365.
3.2. Hydroformylation experiments
[16] C. Scriban, D.S. Glueck, J.A. Golen, A.L. Rheingold, Organometallics 26 (2007)
1788.
[17] B.J. Anderson, D.S. Glueck, A.G. DiPasquale, A. Rheingold, Organometallics 27
(2008) 4992.
A solution of 0.01 mmol of PtCl2(ligand)2 and 3.8 mg (0.02 mmol)
of tin(II) chloride in 10 mL of toluene containing 0.115 mL (1 mmol)
of styrene was transferred under argon into a 100 mL stainless steel
autoclave. The reaction vessel was pressurized to 80 bar total pres-
sure (CO/H2 ¼1/1) and placed in an oil bath of appropriate
temperature and the mixture was stirred with a magnetic stirrer.
Samples were taken from the mixture and the pressure was moni-
tored throughout the reaction. After cooling and venting of the
autoclave, the pale yellow solution was removed and immediately
analyzed by GC and chiral GC (on a capillary Cyclodex-column, (S)-2-
phenylpropanal was eluted before the (R) enantiomer).
[18] B.J. Anderson, M.A. Guino-o, D.S. Glueck, J.A. Golen, A.G. DiPasquale,
L.M. Liable-Sands, A.L. Rheingold, Org. Lett. 10 (2008) 4425.
}
[19] G. Keglevich, M. Sipos, D. Szieberth, L. Nyulászi, T. Imre, K. Ludányi, L. Toke,
Tetrahedron 60 (2004) 6619.
[20] G. Keglevich, M. Sipos, T. Körtvélyesi, T. Imre, L. Toke, Tetrahedron Lett 46
}
(2005) 1655.
}
[21] G. Keglevich, M. Sipos, D. Szieberth, G. Petocz, L. Kollár, J. Organomet. Chem.
689 (2004) 3158.
[22] G. Keglevich, M. Sipos, V. Ujj, T. Körtvélyesi, Lett. Org. Chem. 2 (2005) 608.
[23] G. Keglevich, H. Szelke, A. Kerényi, T. Imre, K. Ludányi, J. Dukai, F. Nagy,
P. Arányi, Heteroatom Chem. 15 (2004) 459.
[24] G. Keglevich, H. Szelke, A. Kerényi, V. Kudar, M. Hanusz, K. Simon, T. Imre,
K. Ludányi, Tetrahedron: Asymmetry 16 (2005) 4015.
[25] G. Keglevich, A. Kerényi, B. Mayer, T. Körtvélyesi, K. Ludányi, Transit. Metal.
Chem. 33 (2008) 505.
3.3. Theoretical calculations
[26] G. Keglevich, H. Szelke, A. Kerényi, T. Imre, Transit. Metal. Chem. 31 (2006) 306.
[27] G. Keglevich, A. Kerényi, H. Szelke, K. Ludányi, T. Körtvélyesi, J. Organomet.
Chem. 691 (2006) 5038.
[28] A. Kerényi, A. Balassa, T. Körtvélyesi, K. Ludányi, G. Keglevich, Transit. Metal.
Chem. 33 (2008) 459.
[29] T. Novák, J. Schindler, V. Ujj, M. Czugler, E. Fogassy, G. Keglevich, Tetrahedron:
Asymmetry 17 (2006) 2599.
[30] T. Novák, V. Ujj, J. Schindler, M. Czugler, M. Kubinyi, Z.A. Mayer, E. Fogassy,
G. Keglevich, Tetrahedron: Asymmetry 18 (2007) 2965.
[31] V. Ujj, J. Schindler, T. Novák, M. Czugler, E. Fogassy, G. Keglevich, Tetrahedron:
Asymmetry 19 (2008) 1973.
The structures for the conformational analysis of the cis struc-
tures were built up by PCMODEL [37]. The calculations were per-
formed in gas phase by Gaussian ’03 [38]. A mixed basis set was
used with B3LYP hybrid density functional: 6-31G** for H, C, P, Cl
atoms and LANL2DZ effective core potential for Pt atom. Only
positive normal mode frequencies were obtained for the accepted
geometries.
[32] V. Ujj, P. Bagi, J. Schindler, J. Madarász, E. Fogassy, G. Keglevich, Chirality
(2010) 699.
[33] G. Keglevich, I. Petneházy, P. Miklós, A. Almásy, G. Tóth, L. Toke, L.D. Quin,
Acknowledgments
}
J. Org. Chem. 52 (1987) 3983.
[34] G. Keglevich, K. Újszászy, Á. Szöllosy, K. Ludányi, L. Toke, J. Organomet. Chem.
516 (1996) 139.
[35] Y. Gourdel, A. Ghanimi, P. Pellon, M. Le Corre, Tetrahedron Lett. 34 (1993)
1011.
[36] P. Pongrácz, L. Kollár, A. Kerényi, V. Kovács, V. Ujj, G. Keglevich, J. Organomet.
Chem. 696 (2011) 2234.
[37] K.E. Gilbert, PCMODEL, Version 7.0, Serena Software, Bloomington, IN, USA.
[38] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb,
J.R. Cheeseman, J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant,
J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi,
G. Scalmani, N. Rega, G.A. Petersson, H. Nakatsuji, M. Hada, M. Ehara,
K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, C. Adamo,
J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi,
C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador,
J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M.C. Strain,
O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz,
Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko,
P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng,
A. Nanayakkara, M. Challacombe, P.M.W. Gill, B. Johnson, W. Chen,
M.W. Wong, C. Gonzalez, J.A. Pople, Gaussian 03, Revision B.05. Gaussian, Inc.,
Pittsburgh PA, 2003.
The above project was supported by the Hungarian Scientific
and Research Fund (OTKA K83118 and CK78553). This work is also
connected to the scientific program of the “Development of quality-
oriented and harmonized R þ D þ I strategy and functional model at
BME” project. This project is supported by the New Hungary
Development Plan (Project ID: TÁMOP-4.2.1/B-09/1/KMR-2010-
0002). T.K. is grateful for the Hungarian Supercomputer Center, NIIF
and HPC Szeged, for the computational facility.
}
}
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