Synthesis, coordination behaviour, structural features and use in asymmetric hydrogenations of bifep-type biferrocenes

Article abstract of DOI:10.1039/b816544k

A protocol for the synthesis of C₂- and C₁-symmetric 2,2″-diarylphosphino-substituted biferrocenes (bifep-type ligands) is presented and the preparation of four representatives is described [(S _p,S_p)-2-R¹₂P-2″- R ²₂P-1,1″-biferrocene; 1 (bifep): R¹ = R² = Ph; 2: R¹ = Ph, R² = Cy; 3: R¹ = R² = 3,5-Me₂C₆H₃; 4: R¹ = 3,5-Me_2-4-OMe-C₆H₂, R² = 3,5-(CF₃)₂C₆H₃]. In addition, the synthesis of three palladium(ii) complexes ([PdX₂(L)], 10: L = 1, X = Cl; 11: L = 4, X = Cl; 12: L = 1, X = C₆F₅ and of four bifep ruthenium complexes (13: [RuCl(p-cymene)(1)]PF₆; 14: [RuI(p-cymene)(1)]PF₆; 15: [RuCl(benzene)(1)]PF₆; 16: [RuI(p-cymene)(1)]I) is reported. In the solid state the biferrocene unit of complexes 10, 11 and 15 adopt either a (P)-shaped (10) or an (M)-shaped (11, 15) conformation. In solution, palladium complexes 10 and 11 are present as equilibrium mixtures of rapidly interconverting (P)- and (M)-shaped conformers. Rhodium- and iridium-mediated asymmetric hydrogenations of a number of olefins and one imine give products with only low to moderate enantiomeric excess, while in the ruthenium-catalyzed hydrogenation of ketones a maximum e.e. of 82% is obtained. The low enantioselectivities are assumed to be related to the conformational flexibility of bifep-type ligands.

Full text of DOI:10.1039/b816544k

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PAPER
www.rsc.org/dalton | Dalton Transactions
Synthesis, coordination behaviour, structural features and use in asymmetric
hydrogenations of bifep-type biferrocenes†
Gustavo Espino,b Li Xiao,a Michael Puchberger,c Kurt Mereiter,c Felix Spindler,d Blanca R. Manzano,e
Fe´lix A. Jalo´ne and Walter Weissensteiner*a
Received 22nd September 2008, Accepted 20th January 2009
First published as an Advance Article on the web 20th February 2009
DOI: 10.1039/b816544k
A protocol for the synthesis of C2- and C1-symmetric 2,2¢¢-diarylphosphino-substituted biferrocenes
(bifep-type ligands) is presented and the preparation of four representatives is described
[(Sp,Sp)-2-R1 P-2¢¢- R2 P-1,1¢¢-biferrocene; 1 (bifep): R1 = R2 = Ph; 2: R1 = Ph, R2 = Cy; 3: R1 = R2 =
2
3,5-Me2C6H3; 4: R1 = 23,5-Me2-4-OMe-C6H2, R2 = 3,5-(CF3)2C6H3]. In addition, the synthesis of three
palladium(II) complexes ([PdX2(L)], 10: L = 1, X = Cl; 11: L = 4, X = Cl; 12: L = 1, X = C6F5 and of
four bifep ruthenium complexes (13: [RuCl(p-cymene)(1)]PF6; 14: [RuI(p-cymene)(1)]PF6; 15:
[RuCl(benzene)(1)]PF6; 16: [RuI(p-cymene)(1)]I) is reported. In the solid state the biferrocene unit of
complexes 10, 11 and 15 adopt either a (P)-shaped (10) or an (M)-shaped (11, 15) conformation. In
solution, palladium complexes 10 and 11 are present as equilibrium mixtures of rapidly interconverting
(P)- and (M)-shaped conformers. Rhodium- and iridium-mediated asymmetric hydrogenations of a
number of olefins and one imine give products with only low to moderate enantiomeric excess, while in
the ruthenium-catalyzed hydrogenation of ketones a maximum e.e. of 82% is obtained. The low
enantioselectivities are assumed to be related to the conformational flexibility of bifep-type ligands.
Introduction
Diphosphines based on C2-symmetric biaryl backbones are
widely used as ligands for enantioselective catalysts, with 2,2¢-
bis(diphenylphosphino)-1,1¢-binaphthyl (binap) certainly being
one of the most prominent examples.1 In addition to binaph-
thyl, a number of alternative biaryl-type backbones2 (including
biphenyl, bispyridyl and other bisheteroaromatic ligand scaffolds)
have been investigated. This concept has further been extended
to 2,2¢¢-disubstituted biferrocenes and the synthesis of 2,2¢¢-
bis(diphenylphosphino)-1,1¢¢-biferrocene (bifep)3 and some of its
P-stereogenic analogues4 have been described (e.g. I, Fig. 1). On
using the latter type of ligand, catalytic allylic amination reactions
resulted in products with up to 93% e.e.4
In a previous communication, we briefly described a protocol for
the synthesis of 2,2¢¢-disubstituted biferrocenes that allowed not
only the preparation of C2- but also of C1-symmetric biferrocenes.5
In addition, the use of a few bifep-type ligands in ruthenium-
catalyzed asymmetric hydrogenations of ethyl acetoacetate was
Fig. 1 Binap, bifep, and P-chiral analogues I and II.
aFaculty of Chemistry, University of Vienna, Wa¨hringer Straße 38, 1090,
described as well as structural features of dichloro palladium(II)
Wien, Austria. E-mail: walter.weissensteiner@univie.ac.at
bDepartamento de Qu´ımica, Facultad de Ciencias, Universidad de Burgos,
Pza Misael Ban˜uelos s/n., 09001, Burgos, Spain. E-mail: gespino@ubu.es
complexes of bifep and one C1-symmetric analogue. We noticed
with interest that in the solid-state the helicity of the biferrocene
backbone in these complexes changed on changing the type of
phosphino substituents and this observation was interpreted as
being the result of conformational flexibility of the biferrocene
backbone.
We now describe in detail the synthesis of C2- and
C1-symmetric bifep-type biferrocenes, their coordination be-
haviour and additional rhodium- and ruthenium-mediated asym-
metric hydrogenations of alkenes and ketones. These catalytic
reactions were carried out with catalysts obtained either in situ
cFaculty of Technical Chemistry, Vienna University of Technology,
Getreidemarkt 9/164SC, 1060, Wien, Austria. E-mail: mpuchber@mail.
zserv.tuwien.ac.at, kurt.mereiter@tuwien.ac.at
dSolvias AG, Catalysis & Synthesis, P.O. Box, CH-4002, Basel, Switzerland.
E-mail: felix.spindler@solvias.com
eDepartamento de Qu´ımica Inorga´nica, Orga´nica y Bioqu´ımica, IRICA,
Universidad de Castilla-La Mancha, Avda. C. J. Cela, 10, 13071, Ciudad
Real, Spain. E-mail: blanca.manzano@uclm.es, felix.jalon@uclm.es
† CCDC reference numbers 158065, 158066, 655658 and 703046. For
crystallographic data in CIF or other electronic format see DOI:
10.1039/b816544k
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Fig. 2 Synthesis of ligands 1–4.
from ligands and an appropriate metal source or from isolated
metal ligand complexes. In addition, a more extensive study on
the structural features of palladium and ruthenium complexes of
bifep-type ligands is reported.
Results
Synthesis of ligands and complexes
Fig. 3 Preparation of palladium and ruthenium complexes 10–16.
C2- and C1-symmetric ligands 1–4 were prepared in three steps
from (S,Rp)-5 (Fig. 2), which was easily available from (S)-(4-
methylphenyl)sulfinyl ferrocene.6 An Ullmann-type reaction of
iodide (S,Rp)-5 with Cu powder gave enantiopure (S,S,Sp,Sp)-
2,2¢¢-bis-(p-tolylsulfinyl)-1,1¢¢-biferrocene (6, 77%), which served
as the key intermediate that allowed the stepwise replace-
ment of both p-tolylsulfinyl units. Intermediates 7–9 were ob-
tained by treatment of 6 with t-BuLi (1.2 equiv.) and subse-
quent quenching with the appropriate chloro(diaryl)phosphine
[(S,Sp,Sp)-7, chloro(diphenyl)phosphine, 60% yield; (S,Sp,Sp)-
8, chlorobis(3,5-dimethylphenyl)phosphine, 80%, (S,Sp,Sp)-9,
chlorobis(3,5-dimethyl-4-methoxyphenyl)phosphine, 66%]. In the
final step, the second sulfinyl group was removed by reaction
of 7, 8, or 9 with t-BuLi followed by addition of either a
chloro(diaryl)phosphine or a chloro(dialkyl)phosphine, resulting
in ligands (Sp,Sp)-1 [chloro(diphenyl)phosphine, 49%], (Sp,Sp)-
2 [chloro(dicyclohexyl)phosphine, 10%], (Sp,Sp)-3 [chlorobis(3,5-
dimethylphenyl)phosphine, 30%], and (Sp,Sp)-4 [chlorobis[3,5-
bis(trifluoromethyl)phenyl]phosphine, 42%]. Interestingly, all at-
tempts to transform 6 directly into the C2-symmetric ligands 1 and
3 failed [e.g. by treatment of 6 with 2.2 equiv. of t-BuLi followed by
quenching with a chloro(diaryl)phosphine]. In neither case could
both sulfinyl groups of 6 be replaced in one step by phosphino
substituents.
In order to study the coordination behaviour of bifep-type
ligands, three palladium(II) complexes of ligands 1 and 4, as well as
four ruthenium(II) complexes of bifep (1), were prepared as model
compounds (Fig. 3). In addition, all bifep-ruthenium complexes
weretestedas pre-catalysts in asymmetric hydrogenation reactions.
The dichloro palladium(II) complexes [PdCl2(1)], 10 and
[PdCl2(4)], 11, were prepared by treating the respective ligands
with [PdCl2(MeCN)2] in benzene while reaction of ligand 1
with [Pd(C6F5)2(COD)] in CH2Cl2 gave the bis(pentafluorophenyl)
palladium(II) complex [Pd(C6F5)2(1)], 12. All monocationic ruthe-
nium complexes [RuX(arene)(1)]PF6 were obtained by reaction of
ligand 1 (2 equiv.) in THF with the respective [RuX2(arene)]2 dimer
(1 equiv.) in the presence of AgPF6 (13: [RuCl(p-cymene)(1)]PF6;
14: [RuI(p-cymene)(1)]PF6; and 15: [RuCl(benzene)(1)]PF6). Com-
plex 16, [RuI(p-cymene)(1)]I, was obtained by reacting 2 equiv. of
ligand 1 with [RuI2(p-cymene)]2 in a mixture of CH2Cl2 and MeOH
(4 : 1) in the absence of AgPF6.
The structural integrity of all ligands (1–4) and complexes (10–
16) was assessed by NMR spectroscopy and for ligand 1 and
complexes 10, 11, and 15 single crystals were also studied by
X-ray diffraction (see below). The absolute (Sp,Sp)-configuration
of ligands 1–4 follows from the known absolute configuration
of the starting material (S)-(4-methylphenyl)sulfinyl ferrocene.6
Furthermore, the X-ray data for ligand 1 and complexes 10,
11, and 15 also confirmed the absolute (Sp,Sp)-configuration of
ligands 1 and 4.
Molecular structures of bifep, 1, and complexes [PdCl2(1)] (10),
[PdCl2(4)] (11) and [RuCl(benzene)(1)]PF6 (15), in the solid-state
Single crystals were obtained by vapour-liquid diffusion of diethyl
ether into a solution of the respective ligand or complex in
either CHCl3 (1) or CH2Cl2 (11) or by liquid–liquid diffusion
of ethanol into a solution of 10 in CHCl3, and liquid–liquid
diffusion of hexane into a solution of 15 in acetone. Details for
the X-ray crystallography experiments are given in Table 1 and
in the Experimental. Views of the molecular structures of these
compounds are shown in Fig. 4 and selected geometrical data are
given in Table 2. The absolute configuration of each compound
was determined from the X-ray anomalous dispersion effects and
was consistent with the chemical evidence.
Ligand (Sp,Sp)-1 crystallizes in the orthorhombic space group
P212121 and contains one molecule per asymmetric unit. Although
in the crystal 1 is found in an asymmetric environment, it adopts
a clear C2 pseudosymmetry when viewed perpendicular to the
2752 | Dalton Trans., 2009, 2751–2763
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Table 1 Details for the crystal structure determinations of complexes (Sp,Sp)-1, (Sp,Sp)-[PdCl2(1)] (10), (Sp,Sp)-[PdCl2(4)] (11), and (Sp,Sp)-
[RuCl(C6H6)(1)]PF6 (15)
(Sp,Sp)-[PdCl2(1)]·
2CHCl3·H2O (10)
(Sp,Sp)-[PdCl2(4)]·
solv (11)a
(Sp,Sp)-[RuCl(C6H6)(1)]PF6·
solv (15)a
(Sp,Sp)-1
Formula
FW
C44H36Fe2P2
738.37
C44H36Cl2Fe2P2Pd·2CHCl3·H2O
C54H44Cl2F12Fe2O2P2Pd C50H42ClF6Fe2P3Ru
1172.42
0.74 ¥ 0.56 ¥ 0.50
P21 (no. 4)
10.270(3)
22.142(6)
10.282(3)
100.96(2)
2295.5(11)
2
1303.83
0.80 ¥ 0.20 ¥ 0.08
P212121 (no. 19)
13.883(3)
15.914(3)
26.242(5)
—
1097.97
0.24 ¥ 0.06 ¥ 0.04
C2 (no. 5)
26.087(6)
10.143(2)
22.461(5)
123.957(3)
4929.6(18)
4
Crystal size/mm
Space group
0.52 ¥ 0.34 ¥ 0.28
P212121 (no. 19)
8.5119(7)
18.2877(15)
22.2993(19)
—
3471.2(5)
4
1.413
173(2)
0.960
1528
30.0
27 639
0.0315
10 101
9347
433
0.0472
0.0519
0.1064
˚
a/A
˚
b/A
˚
c/A
b/◦
V, A
3
˚
5798(2)
4
Z
r
calcd/g cm-3
1.696
223(2)
1.583
1176
30.0
33 075
0.0510
12 764
12 440
549
0.0461
0.0483
0.1086
-0.04(2)
-1.11/1.36
1.494
297(2)
1.479
297(2)
T/K
m(Mo Ka)/mm-1
1.024
2616
1.090
2216
F(000)
qmax
◦
/
25.0
60 296
23.0
16 994
No. of reflections measured
Rint
0.0682
10 183
8145
0.0799
6755
5010
No. of unique reflections
No. of reflections I > 2s(I)
No. of parameters
R1 (I > 2s(I))b
687
530
0.0482
0.0725
0.1080
-0.04(3)
-0.53/0.59
0.0405
0.0590
0.1056
-0.07(2)
-0.41/0.42
R1 (all data)
wR2 (all data)
Flack parameter
-0.017(12)
-0.26/0.79
-3
˚
D-Fourier peaks min/max/e A
ꢀ
ꢀ
a Solvent squeezed with program PLATON and not contained in chemical formula and quantities derived thereof. b R1 = ꢀFo| - |Fcꢀ/ |Fo|, wR2 =
ꢀ
ꢀ
2
[
(w(Fo - Fc2)2)/ (w(Fo2)2)]1/2
.
biferrocene axis. A view along the biferrocene axis (C1–C6, Fig. 4)
shows the biferrocene unit in an (M)-shaped arrangement with
the substituted Cp-rings Cp (C1-C5) and Cp¢¢ (C6–C10) tilted
with respect to one other by 61◦. In this arrangement P2 is located
The dichloro palladium(II) complex [PdCl2((Sp,Sp)-1)]·2CHCl3·
H2O (10) crystallizes in the monoclinic space group P21 and
contains one molecule per asymmetric unit. Both chloroform
molecules form a non-classical hydrogen bond to chloride Cl1
while one water molecule bridges both chlorides (Cl1 and Cl2)
through two classical hydrogen bonds. The [PdCl2(1)] unit adopts
C2 pseudosymmetry but with the coordinated ligand 1 surprisingly
present in conformation B and not in conformation A, as in the
free ligand. In this conformation the biferrocene backbone is
(P)-shaped with Cp and Cp¢¢ tilted against each other by 20◦ and
˚
˚
2.62 A above Cp and P1 2.63 A above Cp¢¢.
It is interesting to note that a change in the diphenylphosphino
units of bifep to naphthyl(phenyl)phosphino groups induces a
marked change in the conformation of the biferrocenyl back-
bone. For (S,S,Rp,Rp)-2,2¢¢-[bis(1-naphthyl(phenyl)phosphino)]-
1,1¢¢-biferrocene (I, Fig. 1) in the solid state a C2 symmetric
molecular structure has been reported,5 but with the biferrocene
unit adopting a totally different conformation than bifep itself. In
this conformation b◦oth substituted Cp rings are tilted with respect
˚
the phosphorus atoms P1 and P2 positioned 1.1 A below Cp¢¢ and
Cp, respectively.
Complex [PdCl2((Sp,Sp)-4)]·solv. (11) crystallizes in the or-
thorhombic space group P212121 and contains one molecule per
asymmetric unit. This palladium complex is asymmetric but in
this case the cis-coordinated ligand 4 is present in conformation
A. The biferrocene unit is (M)-shaped with the substituted Cp
˚
to each other by 142 , an arrangement that places P1 and P2 1.33 A
below Cp¢¢ and Cp, respectively (for a schematic representation see
Fig. 5, conformer C).
According to simple force field calculations,7 four arrange-
ments of the biferrocene backbone seem to be feasible for
C2-symmetric bifep-type ligands. All of these conformers are
expected to be interconvertible through rotation of the fer-
rocene units about the biferrocene axis (Fig. 5). Experimen-
tal evidence for this model comes from the X-ray diffrac-
tion data of biferrocenes 1, I, and II. Diphosphine (Sp,Sp)-1
(bifep) adopts conformation A, the P-stereogenic analogue I
conformation C and its bis(phosphineoxide) (R,R,Rp,Rp)-2,2¢¢-
[bis(1-naphthyl(phenyl)phosphinyl)]-1,1¢¢-biferrocene (II, Fig. 1)
conformation D. For geometric reasons it is obvious that for
cis-coordinated chelate complexes only ligands adopting either
conformation A or B are feasible.
◦
˚
rings rotated against each other by 65 (P2 2.7 A above Cp and
˚
P1 2.7 A above Cp¢¢). At the peripheral parts of the molecule sig-
nificant thermal motion and disorder is observed and this mainly
concerns the trifluoromethyl groups. Interestingly, one aryl ring of
the bis[3,5-bis(trifluoromethyl)phenyl]phosphino unit, C21-C26,
shows clear p–p-stacking with Cp¢¢ while the corresponding ring of
the bis(3,5-dimethyl-4-methoxyphenyl)phosphino unit, C37-C42,
lacks such an interaction with Cp.
The ruthenium complex [RuCl(benzene)((Sp,Sp)-1)]PF6·solv.
(15) crystallizes in the monoclinic space group C2 and contains
one molecule per asymmetric unit. The overall structural features
of this asymmetric cationic complex are as expected. Chloride,
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Table 2 Geometrical parameters of complexes (Sp,Sp)-1, (Sp,Sp)-[PdCl2(1)] (10), (Sp,Sp)-[PdCl2(4)] (11), and (Sp,Sp)-[RuCl(C6H6)(1)]PF6 (15)
(Sp,Sp)-1
(Sp,Sp)-[PdCl2(1)]·2CHCl3·H2O (10)
(Sp,Sp)-[PdCl2(4)]·solv (11)
(Sp,Sp)-[RuCl(C6H6)(1)]PF6·solv (15)
˚
Bond lengths/A
ꢁFe1–C(Cp)ꢂ
ꢁFe1–C(Cp¢)ꢂ
ꢁFe2–C(Cp¢¢)ꢂ
ꢁFe2–C(Cp¢¢¢)ꢂ
C1–C6
Pd,Ru–P1
Pd,Ru–P2
Pd,Ru–Cl1
Pd–Cl2
ꢁRu–(Cbenzene)ꢂ
2.050(3)
2.052(3)
2.051(3)
2.056(3)
1.477(3)
—
—
—
—
—
2.050(6)
2.046(7)
2.054(6)
2.056(6)
1.481(7)
2.274(2)
2.267(2)
2.366(2)
2.367(2)
—
2.042(5)
2.058(6)
2.044(5)
2.035(5)
1.451(6)
2.248(1)
2.284(1)
2.346(2)
2.341(2)
—
2.037(8)
2.032(8)
2.041(8)
2.033(8)
1.484(10)
2.352(2)
2.341(2)
2.363(2)
—
2.210(7)
Bond angles/◦
C2–P1–Pd,Ru
C7–P2–Pd,Ru
P1–Pd,Ru–P2
P1–Pd,Ru–Cl1
P2–Pd,Ru–Cl2
Cl1–Pd–Cl2
—
—
—
—
—
—
124.7(2)
125.8(2)
98.83(5)
86.34(6)
86.64(6)
88.55(6)
110.8(2)
118.4(2)
93.45(5)
91.74(6)
85.56(6)
90.34(6)
124.0(2)
114.3(2)
91.8(1)
87.5(1)
86.3(1)
—
˚
Normal distance of atom from L.S. plane through ring Cp (C1 to C5) or Cp¢¢ (C6 to C10)/A
Pd,Ru/Cp
P1/Cp
P2/Cp
Cl1/Cp
Cl2/Cp
Pd,Ru/Cp¢¢
P1/Cp¢¢
P2/Cp¢¢
Cl1/Cp¢¢
Cl2/Cp¢¢
—
-0.686(16)
0.246(10)
2.553(8)
0.345(8)
2.739(8)
2.502(12)
4.889(9)
1.957(10)
2.656(7)
0.119(7)
3.953(13)
1.053(14)
0.857(20)
0.196(13)
1.914(16)
-1.108(20)
—
2.496(13)
2.182(15)
0.302(11)
3.059(6)
—
0.047(4)
2.621(4)
—
—
—
2.627(4)
0.059(4)
—
-1.060(14)
-0.211(21)
-1.874(22)
-0.630(16)
-1.056(15)
0.256(10)
-1.691(23)
-0.112(21)
—
Interplanar angles/◦
Cp ∧ Cp¢¢
61.4(1)
19.8(3)
65.0(2)
50.1(3)
Dihedral angles/◦
C2–C1–C6–C7
C6–C1–C2–P1
C1–C6–C7–P2
C1–C2–P1–Pd,Ru
C6–C7–P2–Pd,Ru
-115.3(3)
-0.9(3)
-0.9(3)
—
28.7(10)
6.7(10)
2.1(11)
-46.1(7)
-41.9(7)
-58.5(6)
9.2(6)
-3.3(6)
77.1(4)
57.6(4)
-52.6(11)
10.4(12)
14.5(10)
10.4(9)
—
63.9(6)
benzene and bifep are coordinated to Ru(II) in a tetrahedral fash-
ion to form a three-legged piano stool complex. The biferrocene
backbone is (M)-shaped and the ligand adopts conformation A
31P signals was made using standard one- and two-dimensional
techniques. The main structural information was obtained from
proton spectra and, predominately, from NOESY and ROESY
spectra.
◦
˚
with a Cp/Cp¢¢ tilt angle of 50 , P1 is 1.9 A above Cp¢¢ and P2 is
1
˚
2.1 A above Cp.
On the basis of the H NMR spectrum (250 MHz, CD2Cl2,
300 K), in solution complex [PdCl2(1)] appears to adopt a twofold
symmetry consistent with the pseudo C2 symmetric solid state
structure. However, for some of the signals severe line broadening
was observed, indicating the presence of dynamic exchange.
Indeed, variable temperature measurements in the range 300–
190 K showed that on cooling the sample from 300 K to 240 K
each of the Cp-proton signals split into two signals in a 5 : 1
ratio. Since both interconverting species exhibit twofold symmetry,
the observed exchange phenomenon is likely to be caused by the
Molecular structures of complexes [PdCl2(1)] (10), [PdCl2(4)] (11),
[RuCl(p-cymene)(1)]PF6 (13), [RuI(p-cymene)(1)]PF6 (14),
[RuCl(benzene)(1)]PF6 (15), and [RuCl(benzene)(1)]I (16),
in solution
The molecular structures of complexes 10, 11, 13–16 in solution
were determined by NMR spectroscopy, mainly by analyzing
1
nuclear Overhauser interactions. The assignment of H, 13C and
2754 | Dalton Trans., 2009, 2751–2763
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Fig. 5 Schematic representation of feasible conformers of C2-symmetric
bifep-type ligands.
observed. Below 280 K all exchanging signals sharpened again
(without a detectable decoalescence) and at 260 K the Cp¢
(d 3.98 and 4.09 ppm) as well as two aryl ortho proton signals
had fully reappeared while the remaining aryl ortho signals of
one 3,5-dimethyl-4-methoxyphenyl (d 8.09 ppm) and one 3,5-
bis(trifluoromethyl)phenyl ring (d 8.43 ppm) had started to
broaden again. In addition, below 240 K one aryl methyl signal
was also affected by an exchange process. Finally, at 200 K this
methyl signal as well as the aforementioned aryl ortho proton
signals had split into two signals of equal intensity (3,5-dimethyl-
4-methoxyphenyl ring: CH3 d 2.21 and 2.36 ppm; ortho protons
d 6.92 and 7.89 ppm; 3,5-bis(trifluoromethyl)phenyl ring: ortho
protons d 7.62 and 8.77 ppm).
In a similar way to complex [PdCl2(1)], we consider that the
exchange process observed at higher temperature (300–260 K) is
the result of two interchanging conformers of complex [PdCl2(4)]
having either a (P)- or an (M)-shaped biferrocene backbone but
with one conformer present in only a very small amount.
The second exchange process observed below 260 K relates
to a slowed rotation of one 3,5-dimethyl-4-methoxyphenyl and
one 3,5-bis(trifluoromethyl)phenyl ring about their respective
P–C(aryl) bond. Free energy of activation values of DGπ = 44
2 kJ mol-1 (230 K, 3,5-dimethyl-4-methoxyphenyl ring) and DGπ =
42 2 kJ mol-1 (220 K, 3,5-bis(trifluoromethyl)phenyl ring) have
been calculated for these processes.
Fig. 4 Molecular structures of bifep (1), and complexes [PdCl2(1)] (10),
[PdCl2(4)] (11), and [RuCl(benzene)(1)]PF6 (15) in the solid state. Cp:
C1–C5, Cp¢: C11–C15; Cp¢¢: C6–C10; Cp¢¢¢: C16–C20.
interconversion of the two C2 symmetric conformers of complex
[PdCl2(1)] with the biferrocene backbone adopting either a (P)-
or an (M)-shaped conformation (Fig. 5). On further cooling the
sample from 240 K to 190 K, a second dynamic process was
observed that only affected the phenyl proton signals. This second
process is assigned to a slowed rotation of the phenyl rings about
their respective P–C bond. The conformer interconversion is also
1
1
clearly observed in the VT-13C{ H} and 31P{ H} spectra. In the
13C spectrum at 300 K only one signal for the carbons of the
unsubstituted Cp rings was observed while at 240 K two barely
separated signals in a ratio of approximately 5 : 1 were seen. Two
phosphorus signals are seen in the 31P spectrum at 240 K and on
raising the temperature these broaden and finally coalesce at about
300 K. From the proton spectra the free energy of activation for the
conformer exchange process was calculated to be approximately
DGπ = 58 3 kJ mol-1 (260 K, major to minor conformer) and
DGπ = 54 3 kJ mol-1 (minor to major conformer).8
The NMR spectra of complex [PdCl2(4)] are consistent with
the presence of one C1 symmetric conformer but, as in the
case of [PdCl2(1)], the r.t. proton NMR spectrum (250 MHz,
CD2Cl2, 300 K) points to an exchange process. In comparison
to all other resonances the signals of both unsubstituted Cp rings
and of all aryl ortho protons are significantly broadened. VT-1H
NMR spectroscopy in the range 300–200 K again showed two
independent exchange processes. When the sample was cooled
from 300 K to 280 K, further broadening of the Cp¢ and aryl
ortho proton signals occurred but signal splitting could not be
In solution, the ruthenium complexes 13–16 adopt a C1
symmetric molecular structure. The 1H NMR spectra (400 MHz,
acetone-d6, 300 K) of these complexes showed a uniform pattern
for all ferrocene signals but, unlike the dichloro palladium
complexes [PdCl2(1)] and [PdCl2(4)], the variable temperature
spectra recorded e.g. for complex [RuI(p-cymene)(1)]PF6 (14) in
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the temperature range 300–200 K did not show any evidence
of an exchange process related to a conformer equilibrium. A
conformational analysis showed that in solution the biferrocene
backbone of complexes 13–15 prefer an (M)-shaped arrangement,
which is consistent with the (M)-shaped molecular structure found
for [RuCl(benzene)(1)]PF6 (15) in the solid-state. The (M)-shaped
biferrocene conformation could be deduced from NOE interac-
tions of selected ferrocene proton signals. For a given complex
all of the ferrocene signals could be unequivocally ascribed to the
individual ferrocene units (of the biferrocene backbone) and, as
a result, we were able to record NOE interactions between these
units. In each case, the ROESY spectra of complexes 13–15 showed
rather intense cross peaks between protons from the unsubstituted
Cp-ring of one ferrocene unit to one proton of the substituted
Cp-ring of the second ferrocene unit (e.g. from Cp-H5 to Cp¢¢¢-H;
for a graphical representation see Fig. 6) and such interactions are
only consistent with the (Sp,Sp)-configured bifep ligand adopting
an (M)-shaped conformation.
In summary, in palladium and ruthenium coordination com-
pounds of (Sp,Sp)-bifep-type ligands the biferrocene unit can
adopt either a (P)- or an (M)-shaped conformation. In the
solid-state, for dichloro palladium complexes both (P)- and
(M)-shaped conformers were found, while in the ruthenium com-
plex [RuCl(benzene)(1)]PF6 the biferrocene unit prefers the
(M)-shaped arrangement. In solution, the palladium complexes
are present as an equilibrium mixture of rapidly interconverting
(P)- and (M)-shaped conformers. In all of the investigated
ruthenium arene complexes the bifep ligand adopts exclusively
an (M)-shaped conformation.
Fig. 6 Numbering scheme and main Overhauser interactions used for
NMR signal and structural assignment (schematic representation of
[RuCl(p-cymene)(1)]+).
Rh, Ru, or Ir source and ligands of (Sp,Sp) configuration. In most
hydrogenations (except for the substrate MCA) conversion ranged
from acceptable to nearly quantitative. However, for all olefins and
the imine tested, products with very low enantiomeric excess values
were obtained. Only the ruthenium-promoted hydrogenation of
ethyl acetoacetate (EAA, entry 9) gave a product with reasonably
high e.e. (82%). Therefore, further hydrogenation experiments were
carried out with EAA as well as with two additional b-keto
derivatives (ethyl benzoylacetate, EBA, and acetylacetone, ACA).
For this purpose not only catalysts prepared in situ but also the
isolated ruthenium complexes 13–16 were used as pre-catalysts.
However, preparatively useful results could not be obtained in
either case. Interestingly, for all three substrates tested, catalysts
prepared in situ gave products with significantly higher e.e. values.
Enantioselective hydrogenations
Diphosphine ligands (Sp,Sp)-1, 3, and 4 were tested in catalytic
hydrogenations of several olefins, ketones and one imine (for the
catalytic results see Tables 3 and 4, for substrates tested see Fig. 7).
In these cases all catalysts were formed in situ using an appropriate
Table 3 Results obtained in the ruthenium-, rhodium-, and iridium-catalyzed hydrogenation of olefins, ketones, and one imine with ligands 1, 3, and 4
Product
configuration
Entry Substratea
Ligand
Catalyst precursorb
S/C
Solventc
p(H2)/bar T/◦C
Time/h Conv. (%)
e.e. (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
MAC
MAC
MCA
MCA
MCA
PCA
DMI
DMI
EAA
EAA
EAA
EPY
1
4
1
3
4
1
1
4
1
3
4
1
3
1
3
4
[Rh(NBD)2]BF4
[Rh(NBD)2]BF4
[Rh(NBD)2]BF4
[Rh(NBD)2]BF4
[Rh(NBD)2]BF4
[Rh(NBD)2]BF4
[Rh(NBD)2]BF4
[Rh(NBD)2]BF4
[RuI2(p-cymene)]2
[RuI2(p-cymene)]2
[RuI2(p-cymene)]2
[RhCl(COD)2]2
[RhCl(COD)2]2
[IrCl(COD)2]2
200
200
200
200
200
200
200
200
1000
1000
1000
10
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
EtOH
EtOH
EtOH
Toluene
Toluene
Toluene
Toluene
Toluene
1
1
5
5
5
80
1
1
80
80
80
40
40
80
80
80
25
25
25
25
25
25
25
25
80
80
80
25
25
25
25
25
16
16
15
15
>99
>99
9
21
5
37
48
32
8
S
S
S
R
N.d.
S
15
N.d.
35
23
13
82
68
20
33
57
33
21
28
14.5
17.5
18
19
19
16
18
16
95
>99
>99
>99
>99
96
26
98
41
71
>99
R
R
R
R
R
R
R
S
EPY
100
MEAI
MEAI
MEAI
1000
1000
1000
15.5
15.5
15.5
[IrCl(COD)2]2
[IrCl(COD)2]2
S
S
a For substrates see Fig. 7, NBD = norbornadiene, COD = cycloocta-1,5-diene. b Ligand/catalyst precursor: [Rh(NBD)2]BF4: 1.05; [RuI2(p-cymene)]2:
2.2; [RhCl(COD)2]2 and [IrCl(COD)2]2: 2.1. c Additives: substrates EAA and EPY (entries 9–13): 1 M HCl (60 mL); MEAI (entries 14–16): CF3COOH
(30 mL); tetrabutylammonium iodide (TBAI): 2 equiv./Ir.
2756 | Dalton Trans., 2009, 2751–2763
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Table 4 Ruthenium-catalyzed hydrogenation of ketones with catalysts prepared in situ or using complexes 13–16
Additives 1 M
HCl/mL
Product
configuration
Entry
Substrate
Catalyst precursor
Time/h
Conv. (%)
e.e. (%)
dl : meso
9
17
18
19
20
21
22
23
24
25
26
EAA
EAA
EAA
EAA
EAA
EBA
EBA
EBA
ACA
ACA
ACA
1 + [RuI2(p-cymene)]2
[RuCl(p-cymene)2(1)]PF6
[RuI(p-cymene)2(1)]PF6
[RuI(p-cymene)2(1)]PF6
[RuI(p-cymene)2(1)]I
1 + [RuI2(p-cymene)]2
[RuI(p-cymene)2(1)]PF6
[RuI(p-cymene)2(1)]I
1 + [RuI2(p-cymene)]2
[RuI(p-cymene)2(1)]PF6
[RuI(p-cymene)2(1)]I
60
60
60
19
21
21
20.5
20.5
16
16
20.5
19
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
61
82
65
69
66
61
54
46
43
72
63
59
R
—
—
—
—
—
—
—
—
R
R
60/TBAI
R
60
60
60
60
60
60
60
R
S
S
S
2R,4R
2R,4R
2R,4R
97 : 3
96 : 4
97 : 3
18
20
Substrate: 6.45 mmol; S/C: 1000; solvent: EtOH (15 mL); p(H2): 80 bar; T: 80 ◦C.
iridium-catalyzed asymmetric hydrogenations of olefins, ketones
and one imine resulted in products with poor to moderate
enantioselectivities. The use of ethyl acetoacetate as the substrate
did provide a product with 82% e.e. It is assumed that the overall
poor to moderate performance of bifep-based catalysts is—at least
in part—caused by the lack of conformational stability of the
biferrocene ligand backbone.
Experimental
General comments
Melting points were determined on a Kofler melting point
apparatus and are uncorrected. NMR spectra were recorded on
a Bruker DRX 400, Varian Unity Inova-400 or a Bruker DPX
250 spectrometer. Chemical shifts d are reported in ppm and
are referenced relative to CHCl3 (7.26 and 77.00 ppm for 1H
and 13C), CHDCl2 (5.32 for 1H), CD2Cl2 (53.8 ppm for 13C),
TMS (acetone-d6, 0 ppm for 1H and 13C), CFCl3 (0 ppm for
19F), and 85% H3PO4 (0 ppm for 31P), coupling constants are
Fig. 7 Substrates used in enantioselective hydrogenation reactions.
1
reported in Hz. In the H NMR data, br s, d, t, q, and spt refer
Overall, in hydrogenations of ketones the bifep-type ligands
tested (1, 3, and 4) did not perform anywhere near as well as binap-
type or comparable biaryl-based ligands. It seems reasonable to
assume that the performance of bifep-based catalysts is strongly in-
fluenced by the lack of conformational stability of the biferrocene
ligand backbone resulting in a severe drop in enantioselectivity.
to broad singlet, doublet, triplet, quartet and septet, respectively,
and Cq in 13C NMR data stands for quaternary carbon atom.
Coupling constants listed in 13C NMR data refer to 13C–31P
couplings, unless stated otherwise. Mass spectra were measured
on a Varian MAT-CH7 or a Finnigan MAT 8230 spectrometer
(E.I., 70 eV, unless stated otherwise). FAB+ mass spectra were
recorded on a Micromass AutoSpec instrument. Optical rotations
were measured on a Perkin-Elmer 241 polarimeter in CHCl3 at
20 ◦C. CD spectra were recorded on a dichrograph JOBIN YVON
CD 6 in CH2Cl2 at 20 ◦C. Elemental analyses were performed at the
Mikroanalytisches Laboratorium der Universita¨t Wien (Mag. J.
Theiner) or were measured on a LECO CHNS932 microanalyser.
All reactions requiring inert conditions were conducted under
Ar or N2, using standard Schlenk techniques. Diethyl ether
was distilled from lithium aluminium hydride, acetonitrile and
benzene were distilled from calcium hydride, and THF was dried
over potassium/benzophenone prior to use. Chromatographic
separations were performed under gravity either on silica gel
(MERCK, 40–63 mm) or on alumina (MERCK, activity II–III,
0.063–0.200 mm). Petroleum ether (PE) with a boiling range of
55–65 ◦C was used for chromatography. Copper was activated
Concluding remarks
A method for the synthesis of C2- and C1-symmetric bifep-type
ligands has been developed and four representative derivatives
have been synthesized. The coordination behaviour of these
compounds has been studied as along with structural features of
the dichloro palladium and ruthenium arene complexes. In both
the solid-state and in solution, bifep-based complexes were found
to adopt different conformations with the biferrocene backbone
present either in a (P)- or an (M)-shaped conformation. Variable-
temperature NMR measurements indicate that in solution the
dichloro palladium complexes in particular are present as equi-
libria of rapidly interconverting (P)- and (M)-shaped conformers.
The use of three bifep-type ligands in rhodium-, ruthenium- and
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according to ref. 9, (S)-(4-methylphenyl)sulfinyl-ferrocene6 and
complexes [RuCl2(p-cymene)]2, [RuCl2(benzene)]2 and [RuI2(p-
cymene)]2 were prepared as described previously.
J = 16.0, CH2), 29.6 (1 C, CH2), 29.7 (1 C, d, J = 13.7, CH2), 31.1
(1 C, d, J = 16.7, CH2), 34.0 (1 C, d, J = 25.9, CH2), 34.9 (1 C, d,
J = 10.6, CH), 37.1 (1 C, d, J = 12.9, CH), 68.8 (1 C, Cp–CH),
69.8 (5 C, Cp¢–CH), 69.9 (5 C, Cp¢–CH), 70.0 (1 C, Cp–CH), 71.1
(1 C, d, J = 3.8, Cp–CH), 71.6 (1 C, d, J = 4.6, Cp–CH), 74.8 (1
C, dd, J = 3.8, J = 8.4, Cp–CH), 75.8 (1 C, dd, J = 4.8, J = 8.4,
Cp–CH), 77.6 (1 C, d, J = 12.2, Cp–Cq), 82.6 (1 C, d, J = 21.3,
Cp–Cq), 91.0 (1 C, dd, J = 3.0 and 25.8, Cp–C), 92.7 (1 C, dd, J =
3.0, J = 31.9, Cp–C), 127.1 (1 C, Ph–CH), 127.6 (2 C, d, J = 5.3,
2 Ph–CH), 128.0 (2 C, d, J = 8.4, 2 Ph–CH), 129.0 (1 C, Ph–CH),
132.4 (2 C, d, J = 17.5, 2 Ph–CH), 135.4 (2 C, d, J = 22.8, 2
Ph–CH), 140.2 (1 C, d, J = 7.6, Ph–C), 140.5 (1 C, d, J = 9.9,
10
General procedure for the preparation of biferrocenes 1–4
To a solution of compound 7, 8 or 9 (1 mmol) in THF was added
dropwise t-BuLi (0.71 mL, 1.7 M in pentane, 1.2 mmol) under Ar
at -78 ◦C. After stirring for an additional 5 min, the appropriate
chloro(diaryl)- or chloro(dialkyl)phosphine (1.3 mmol) was added
at the same temperature. The reaction mixture was allowed to
warm to r.t. and was stirred for 2–16 h. After quenching with
saturated NaHCO3 solution, the organic phase was separated,
and washed with water and brine. After drying over MgSO4 the
solvent was removed under reduced pressure and the residue was
purified by column chromatography on silica or alumina.
1
Ph–C). 31P{ H} NMR (162 MHz; CDCl3) d -23.9 (PPh2), -31.1
◦
(PCy2). MS (EI, 210 C) m/z (rel%) = 667 (100, M+ - Cy), 584
(18, M+ - 2Cy). HRMS found: 750.1952; calcd (for C44H48Fe2P2):
20
750.1933. [a]l = +166 (589 nm), +201 (578 nm), +416 (546 nm)
(c = 0.50 in CHCl3). CD De (lmax) = +4.0 (300 nm), -1.7 (353 nm),
(Sp,Sp)-2,2¢¢-Bis(diphenylphosphino)-1,1¢¢-biferrocene 1. Com-
pound 1 was synthesized from (S,Sp,Sp)-7 (400 mg, 578 mmol, in
150 mL THF) and Ph2PCl (166 mg, 754 mmol). Reaction time:
16 h. Chromatography on alumina; elution with PE/Et2O/Et3N
(100/2/1 → 60/3/1 → 20/3/1) afforded (Sp,Sp)-1 as a yellow
solid (209 mg, 49%).
+3.4 (481 nm) (c = 9.99 ¥ 10-4 mol L-1 in CH2Cl2).
(Sp,Sp)-2,2¢¢-Bis[bis(3,5-dimethylphenyl)phosphino]-1,1¢¢-bifer-
rocene 3. Compound 3 was synthesized from (S,Sp,Sp)-8
(1.414 g, 1.89 mmol, in 40 mL THF) and chloro-bis(3,5-dimethyl-
phenyl)phosphine (680 mg, 2.46 mmol, in 10 mL THF). Re-
action time: 2 h. Chromatography on alumina; elution with
PE/Et2O/Et3N (100/4/1) afforded (Sp,Sp)-3 as a yellow solid
(482 mg, 30%; in solution this compound is very sensitive to air).
Mp 190 ◦C (dec). Found: C 72.98, H 6.22. C52H52Fe2P2 requires
C 73.42, H 6.16%.
Mp 221 ◦C. Found: C 71.26, H 4.83. C44H36Fe2P2 requires C
1
71.57, H 4.91%. H NMR (400.1 MHz; CDCl3) d 3.97 (2 H, m,
Cp–H), 4.04 (10 H, s, Cp¢–H), 4.53 (2 H, m, Cp–H), 4.94 (2 H,
m, Cp–H), 6.66–6.72 (8 H, m, Ph–H), 6.78–6.83 (2 H, m, Ph–H),
1
7.34–7.38 (6 H, m, Ph–H), 7.52–7.57 (4 H, m, Ph–H). 13C{ H}
1H NMR (400.1 MHz; CDCl3) d 1.78 (12 H, s, 4 CH3), 2.34
(12 H, s, 4 CH3), 3.97 (2 H, m, 2 Cp–H), 4.00 (10 H, s, Cp¢–H),
4.51 (2 H, m, 2 Cp–H), 4.90 (2 H, m, 2 Cp–H), 6.26 (4 H, d, J =
7.3, Ph–H), 6.45 (2 H, s, Ph–H), 7.03 (2 H, s, Ph–H), 7.20 (4 H, d,
NMR (100.6 MHz; CDCl3) d 69.95 (10 C, 2 Cp¢–CH), 69.98 (2 C,
2 Cp–CH), 71.5 (2 C, d, J = 5.3, 2 Cp–CH), 76.12 (2 C, dd, J =
4.6, J = 8.4, 2 Cp–CH), 78.4 (2 C, d, J = 10.6, 2 Cp–Cq), 91.1
(2 C, dd, J = 3.0, J = 32.7, 2 Cp–Cq), 126.8 (2 C, 2 Ph–CH),
127.3 (4 C, d, J = 5.3, 4 Ph–CH), 128.0 (4 C, d, J = 8.4, 4 Ph–
CH), 129.0 (2 C, 2 Ph–CH), 131.4 (4 C, d, J = 16.7, 4 Ph–CH),
135.4 (4 C, d, J = 22.8, 4 Ph–CH), 139.5 (2 C, d, J = 9.1, 2 Ph–
1
J = 8.3, Ph–H). 13C{ H} NMR (100.6 MHz; CDCl3) d 20.9 (4 C, 4
CH3), 21.4 (4 C, 4 CH3), 69.8 (12 C, br s, 10 Cp¢–CH + 2 Cp–CH),
70.7 (2 C, d, J = 4.5, 2 Cp–CH), 75.8 (2 C, dd, J = 4.6, J = 7.6,
2 Cp–CH), 79.6 (2 C, d, J = 11.4, 2 Cp–Cq), 91.3 (2 C, dd, J =
3.0, J = 29.7, 2 Cp–Cq), 128.4 (2 C, 2 Ph–CH), 129.2 (4 C, d, J =
16.7, 4 Ph–CH), 130.7 (2 C, 2 Ph–CH), 133.3 (4 C, d, J = 22.0, 4
Ph–CH), 136.5 (4 C, d, J = 5.3, 4 Ph–Cq); 137.2 (2 C, d, J = 8.4,
4 Ph–Cq), 139.6 (2 C, d, J = 9.1, 2 Ph–Cq), 139.8 (2 C, d, J = 7.8,
1
Cq), 139.8 (2 C, d, J = 7.6, 2 Ph–Cq). 31P{ H} NMR (162 MHz;
◦
CDCl3) d = -23.2. MS (EI, 230 C) m/z (rel%) = 738 (42, M+),
661 (100, M+ - Ph), 552 (8, M+ - Ph2P). HRMS found: 738.0967;
20
calcd (for C44H36Fe2P2): 738.0991. [a]l = +151 (589 nm), +182
(578 nm), +377 (546 nm) (c = 0.22 in CHCl3). CD De (lmax) =
+469 (244 nm), +35.0 (312 nm), -20.3 (351 nm), +33.2 (478 nm)
(c = 1.06 ¥ 10-3 mol L-1 in CH2Cl2).
1
2 Ph–Cq). 31P{ H} NMR (162 MHz; CDCl3) d -22.4. MS (EI,
100 ◦C) m/z (rel%) = 850 (8, M+), 745 (14, M+ - C6H3(CH3)2), 58
(100). HRMS found: 850.2309; calcd (for C52H52Fe2P2): 850.2243.
(Sp,Sp)-2-Dicyclohexylphosphino-2¢¢-diphenylphosphino-1,1¢¢-
biferrocene 2. Compound 2 was synthesized from (S,Sp,Sp)-7
(825 mg, 1.19 mmol, in 320 mL THF) and Cy2PCl (360 mg,
1.55 mmol). Reaction time: 2 h. Chromatography on alumina; elu-
tion with PE/Et2O/Et3N (100/2/1 → 60/6/1) afforded (Sp,Sp)-2
as a yellow solid (89 mg, 10%).
20
[a]l = +126 (589 nm), +145 (578 nm), +272 (546 nm) (c = 0.40
in CHCl3). CD De (lmax) = +31.5 (251 nm), +2.5 (307 nm), -1.3
(352 nm), +2.1 (478 nm) (c = 8.80 ¥ 10-4 mol L-1 in CH2Cl2).
(Sp,Sp)-2-Bis(3,5-dimethyl-4-methoxyphenyl)phosphino-2¢¢-bis-
[3,5-bis(trifluoromethyl) phenyl]phosphino-1,1¢¢-biferrocene 4.
Mp 196 ◦C. Found: C 70.29, H 6.42. C44H48Fe2P2 requires C
70.42, H 6.45%. 1H NMR (400.1 MHz; CDCl3) d 0.60–0.69 (4 H,
m, Cy), 0.83–0.90 (3 H, m, Cy), 1.21–1.43 (8 H, m, Cy), 1.51–1.56
(1 H, m, Cy), 1.71–1.75 (1 H, m, Cy), 1.81–1.89 (2 H, m, Cy), 2.00–
2.17 (3 H, m, Cy), 3.92 (5 H, s, Cp¢–H), 4.15 (1 H, m, Cp–H), 4.28
(1 H, m, Cp–H), 4.34 (5 H, s, Cp¢–H), 4.51 (1 H, m, Cp–H), 4.56
(1 H, m, Cp–H), 4.79 (1 H, m, Cp–H), 4.89 (1 H, m, Cp–H), 7.09–
7.12 (3 H, m, Ph–H), 7.15–7.20 (2 H, m, Ph–H), 7.36–7.38 (3 H,
Compound 4 was synthesized from (S,Sp,Sp)-9 (1.596 g,
1.97 mmol, in 40 mL THF) and chloro-bis[(3,5-bis(trifluoro-
methyl)phenyl]phosphine (1.26 g, 2.56 mmol, in 10 mL THF).
Reaction time: 16 h. Chromatography on alumina; elution with
PE/acetone (100/4) afforded (Sp,Sp)-4 as a yellow solid (931 mg,
42%).
Mp 124 ◦C. Found: C 57.52, H 3.95. C54H44F12Fe2O2P2 requires
1
C 57.57, H 3.94%. H NMR (400.1 MHz; CDCl3) d 1.75 (6 H,
1
m, Ph–H), 7.60–7.65 (2 H, m, Ph–H). 13C{ H} NMR (100.6 MHz;
s, CH3), 2.29 (6 H, s, CH3), 3.38 (3 H, s, OCH3), 3.75 (3 H, s,
OCH3), 3.85 (1 H, m, Cp–H), 3.96 (6 H, br s, 5 Cp¢–H + 1 Cp–H),
4.05 (5 H, s, Cp¢–H), 4.56 (1 H, m, Cp–H), 4.68 (1 H, m, Cp–H),
CDCl3) d 25.9 (1 C, CH2), 26.5 (1 C, CH2), 26.7 (1 C, d, J = 21.3,
CH2), 26.7 (1 C, CH2), 27.8 (1 C, d, J = 4.6, CH2), 28.4 (1 C, d,
2758 | Dalton Trans., 2009, 2751–2763
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4.80 (1 H, m, Cp–H), 5.06 (1 H, m, Cp–H), 6.26 (2 H, d, J = 7.0,
Ph–H), 7.06 (2 H, d, J = 5.6, Ph–H), 7.13 (2 H, d, J = 8.1, Ph–H),
7.43 (1 H, s, Ph–H), 7.91 (2 H, d, J = 7.0, Ph–H), 7.98 (s, 1 H,
Cp–Cq), 125.5 (2 C, 2 Ph–CH), 129.5 (2 C, 2 Ph–CH), 140.1 (1 C,
Ph–C), 141.5 (1 C, Ph–C). MS (EI, 110 ◦C) m/z (rel%) = 450 (100,
M+), 434 (9, M+ - O), 324 (11, M+ - I). HRMS found: 449.9251;
1
20
Ph–H). 13C{ H} NMR (100.6 MHz; CDCl3) d 15.6 (2 C, 2 CH3),
calcd (for C17H15FeIOS): 449.9238. [a]l = -3.9 (589 nm), -4.0
16.14 (2 C, 2 CH3), 59.1 (1 C, OCH3), 59.8 (1 C, OCH3), 69.8 (5
C, Cp¢–CH), 69.9 (5 C, Cp¢–CH), 70.0 (1 C, Cp–CH), 70.2 (1 C,
d, J = 5.3, Cp–CH), 71.5 (1 C, Cp–CH), 71.9 (1 C, d, J = 4.6,
Cp–CH), 76.0 (1 C, br m, Cp–Cq), 76.0 (1 C, br m, Cp–CH), 77.4
(1 C, d, J = 6.4, Cp–CH), 81.0 (1 C, d, J = 10.6, Cp–Cq), 89.9
(1 C, dd, J = 3.3, J = 30.2, Cp–Cq), 92.8 (1 C, dd, J = 3.6, J =
34.8, Cp–Cq), 121.3 (1 C, m, Ph–CH), 122.8 (2 C, d, J = 271.5,
2 Ph–CF3), 123.0 (2 C, d, J = 271.5, 2 Ph–CF3), 123.4 (1 C, m,
Ph–CH), 129.5 (2 C, d, J = 5.3, 2 Ph–Cq), 130.4 (2 C, d, J =
9.1, 2 Ph–Cq), 130.9 (2 C, m, 2 Ph–CH), 131.7 (2 C, d, J = 17.1,
2 Ph–CH), 131.8 (1 C, q, J = 33.5, Ph-meta [Ph–CF3]), 131.9 (1
C, q, J = 34.0, Ph-meta [Ph–CF3]), 133.8 (1 C, d, J = 9.1, Ph–
Cq), 134.4 (1 C, d, J = 6.8, Ph–Cq), 134.8 (2 C, m, 2 Ph–CH),
135.7 (2 C, d, J = 22.8, 2 Ph–CH), 142.6 (2 C, d, J = 16.7, 2
Ph–Cq), 143.1 (2 C, d, J = 15.2, 2 Ph–Cq), 155.9 (1 C, Ph–C),
(578 nm), -5.4 (546 nm) (c = 0.52 in CHCl3). CD De (lmax) =
-0.7 (258 nm), -3.9 (287 nm), +1.8 (304 nm), -0.5 (354 nm), -0.6
(427 nm) (c = 1.04 ¥ 10-3 mol L-1 in CH2Cl2).
(S,S,Sp,Sp)-2,2¢¢-Bis[(4-methylphenyl)sulfinyl]-1,1¢¢-biferrocene
6. A mixture of finely powdered (S,Rp)-5 (18.3 g, 40.7 mmol)
and ◦activated copper bronze (200 g) was heated under Ar to
130 C for 16 h. The mixture was cooled to r.t. and was washed
repeatedly with CHCl3. After removal of the solvent, the residue
was purified by column chromatography on silica gel. Elution with
PE/acetone/Et3N (10/10/1) resulted in 4.9 g of starting material
5 (first band), and biferrocene (S,S,Sp,Sp)-6 (8.5 g, 65%; 88% based
on recovered 1) as a yellow solid.
Mp 182 ◦C (dec). Found: C 63.07, H 4.69. C34H30Fe2O2S2
requires C 63.17, H 4.68%.
1H NMR (400.1 MHz; CDCl3) d 2.44 (6 H, s, CH3), 4.01 (2 H,
m, Cp–H), 4.37 (12 H, br s, 10 Cp¢–H + 2 Cp–H), 5.14 (2 H,
m, Cp–H), 7.31 (4 H, d, J = 7.9, Ph–H), 7.68 (4 H, d, J = 7.9,
1
158.0 (1 C, Ph–Cq). 31P{ H} NMR (162 MHz; CDCl3) d -25.9,
1
-19.1. 19F{ H} NMR (282.2 MHz; CDCl3) d -62.5, -62.6. MS
(FAB) m/z (rel%) = 1126 (M+). HRMS found: 1126.1327; calcd
1
Ph–H). 13C{ H} NMR (100.6 MHz; CDCl3) d 21.5 (2 C, 2 CH3),
20
(for C54H44F12Fe2O2P2): 1126.1324. [a]l = +1.63 (589 nm), +8.60
68.96 (2 C, 2 Cp–CH), 68.97 (2 C, 2 Cp–CH), 71.2 (10 C, Cp¢–
CH), 76.08 (2 C, 2 Cp–CH), 84.60 (2 C, 2 Cp–Cq), 92.64 (2 C, 2
Cp–Cq), 125.64 (4 C, 4 Ph–CH), 129.32 (4 C, 4 Ph–CH), 140.02
(2 C, 2 Ph–Cq), 141.27 (2 C, 2 Ph–Cq). MS (EI, 200 ◦C) m/z
(rel%) = 646 (48, M+), 630 (100, M+ - O), 614 (38, M+ - 2O), 581
(48, M+ - Cp). HRMS found: 646.0342; calc. (for C34H30Fe2O2S2):
(578 nm), +62.8 (546 nm) (c = 0.43 in CHCl3). CD De (lmax) =
+287 (243 nm), +283 (251 nm), +37.2 (285 nm), +27.3 (311 nm),
-11.0 (352 nm), -3.7 (423 nm), +15.2 (481 nm) (c = 9.90 ¥ 10-4
mol L-1 in CH2Cl2).
(S,Rp)-1-Iodo-2-[(4-methylphenyl)sulfinyl]-ferrocene 5. To
a
20
646.0388. [a]l = -393 (589 nm), -425 (578 nm), -574 (546 nm)
solution of diisopropylamine (7.54 g, 74.7 mmol) in THF (40 mL)
was added dropwise n-BuLi (46.7 mL, 1.6 M in hexane, 74.7 mmol)
at -25 ◦C. After stirring for an additional 30 min this solution
was transferred within 100 min via a cannula into a stirred
suspension of enantiopure (S)-(4-methylphenyl)sulfinyl-ferrocene
(22 g, 67.9 mmol) in THF (400 mL) at -78 ◦C. During this
procedure the sulfoxide dissolved, and stirring of the resulting
red-orange solution was continued for another 30 min before a
solution of iodine (22.7 g, 89.3 mmol) in THF (100 mL) was added
dropwise. After stirring at the same temperature for additional
20 min, the reaction was quenched with water (50 mL). The
aqueous phase was extracted with three portions of Et2O (50 mL
each) and the combined organic layers were washed with aqueous
sodium sulfite, water and brine. After drying with MgSO4 the
solvent was removed under reduced pressure. The crude product
was crystallized from CH2Cl2/hexane to give 12.0 g of (S,Rp)-1 as
yellow crystals. The solvents of the mother liquor were removed
under reduced pressure and the residue purified by column
chromatography on silica gel. Elution with PE/acetone/Et3N
(50/10/1 → 10/10/1) afforded additional 6.3 g of (S,Rp)-1. Total
yield: 18.3 g (60%). Product 1 is light-sensitive in solution and it
is therefore recommended to carry out chromatography with the
exclusion o◦f light.
(c = 0.50 in CHCl3). CD De (lmax) = +16.0 (258 nm), +9.6 (283 nm),
-1.0 (364 nm), -2.0 (429 nm), +1.2 (485 nm) (c = 9.59 ¥
10-4 mol L-1 in CH2Cl2).
General procedure for the preparation of (S,Sp,Sp)-2-
diarylphosphino-2¢¢-(4-methylphenyl)sulfinyl-1,1¢¢-biferrocene 7–9
To a solution of biferrocene derivative (S,S,Sp,Sp)-6 (1.94 g,
3 mmol) in THF (360 mL) was added dropwise t-BuLi (2.1 mL,
1.7 M solution in pentane, 3.6 mmol) under Ar at -78 ◦C. Upon
addition of t-BuLi the colour of the reaction mixture turned red.
After stirring for an additional 5 min, the appropriate chloro-
diarylphosphine (4.5 mmol) was added at the same temperature.
The mixture was allowed to warm up to r.t. and stirring was
continued for 16 h. After quenching with an saturated aqueous
NaHCO3, the organic phase was separated, washed with water
and brine and was dried over MgSO4. The solvent was removed
under reduced pressure and the residue was purified on silica gel.
(S,Sp,Sp )-2-Diphenylphosphino-2¢¢-(4-methylphenyl)sulfinyl-
1,1¢¢-biferrocene 7. Lithiated 6 (3 mmol) was reacted with
Ph2PCl (995 mg, 4.5 mmol). Chromatography: elution with
PE/acetone/Et3N (100/20/1 → 10/10/1) afforded (S,Sp,Sp)-7
as a yellow◦solid (1.24 g, 60%).
Mp 148 C. Found: C 45.54, H 3.35. C17H15FeIOS requires C
1
1
45.36, H 3.36%. H NMR (400.1 MHz; CDCl3) d 2.44 (3 H, s,
Mp 210 C (dec). H NMR (400.1 MHz; CDCl3) d 2.45 (3 H,
CH3), 4.08 (1 H, m, Cp–H), 4.24 (5 H, s, Cp¢–H), 4.35 (1 H, m,
Cp–H), 4.66 (1 H, m, Cp–H), 7.34 (2 H, d, J = 8.1, Ph–H), 7.70
s, CH3), 3.79 (1 H, m, Cp–H), 3.89 (1 H, m, Cp–H), 4.18 (5 H,
s, Cp¢–H), 4.26 (1 H, m, Cp–H), 4.27 (5 H, s, Cp¢–H), 4.48 (1 H,
m, Cp–H), 4.77 (1 H, m, Cp–H), 5.06 (1 H, m, Cp–H), 7.06–7.11
(2 H, m, Ph–H), 7.13–7.20 (3 H, m, Ph–H), 7.33 (2 H, d, J =
7.9, Ph–H), 7.39–7.44 (3 H, m, Ph–H), 7.58–7.63 (2 H, m, Ph–H),
1
(2 H, d, J = 8.1, Ph–H). 13C{ H} NMR (100.6 MHz; CDCl3) d
21.5 (1 C, CH3), 39.4 (1 C, Cp–Cq), 68.6 (1 C, Cp–CH), 70.9 (1
C, Cp–CH), 72.7 (5 C, Cp¢–CH), 78.1 (1 C, Cp–CH), 94.0 (1 C,
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1
7.77 (2 H, d, J = 7.9, Ph–H). 13C{ H} NMR (100.6 MHz; CDCl3)
(2 H, d, J = 7.3, Ph–H), 7.25 (2 H, d, J = 6.3, Ph–H), 7.34 (2 H,
1
d, J = 8.1, Ph–H), 7.78 (2 H, d, J = 8.1, Ph–H). 13C{ H} NMR
d 21.5 (1 C, CH3), 67.6 (1 C, Cp–CH), 68.7 (1 C, Cp–CH), 70.1
(1 C, Cp–CH), 70.3 (5 C, Cp¢–CH), 70.8 (5 C, Cp¢–CH), 72.2 (1 C,
d, J = 4.6, Cp–CH), 74.8 (1 C, d, J = 9.2, Cp–CH), 75.0 (1 C,
d, J = 3.8, Cp–CH), 77.6 (1 C, d, J = 11.4, Cp–Cq), 87.5 (1 C,
Cp–Cq), 88.2 (1 C, d, J = 25.1, Cp–Cq), 93.5 (1 C, Cp–Cq), 125.9
(2 C, 2 Ph–CH), 127.3 (1 C, Ph–CH), 127.9 (2 C, d, J = 5.3, 2
Ph–CH), 128.1 (2 C, d, J = 8.4, 2 Ph–CH), 129.2 (1 C, Ph–CH),
129.3 (2 C, 2 Ph–CH), 132.1 (2 C, d, J = 17.5, 2 Ph–CH), 135.6
(2 C, d, J = 22.0, 2 Ph–CH), 138.4 (1 C, d, J = 10.6, Ph–Cq),
139.5 (1 C, d, J = 9.9, Ph–Cq), 140.7 (1 C, Ph–Cq), 141.4 (1 C,
(100.6 MHz; CDCl3) d 16.0 (2 C, 2 CH3), 16.2 (2 C, 2 CH3), 21.5
(CH3), 59.5 (1 C, OCH3), 59.8 (1 C, OCH3), 67.3 (1 C, Cp–CH),
68.5 (1 C, Cp–CH), 69.9 (1 C, Cp–CH), 70.3 (5 C, Cp¢–CH), 70.9
(5 C, Cp¢–CH), 72.4 (1 C, d, J = 3.8, Cp–CH), 74.8, 74.8, 74.9 (2 C,
2 Cp–CH), 78.3 (1 C, d, J = 12.2, Cp–Cq), 87.9 (1 C, d, J = 1.5,
Cp–Cq), 88.1 (1 C, d, J = 25.1, Cp–Cq), 93.5 (1 C, Cp–Cq), 126.0
(2 C, 2 Ph–CH), 129.3 (2 C, 2 Ph–CH), 130.3 (2 C, d, J = 3.8, 2
Ph–Cq), 130.4 (2 C, d, J = 6.1, 2 Ph–Cq), 132.5 (2 C, d, J = 18.2, 2
Ph–CH), 133.3 (1 C, d, J = 9.1, Ph–Cq), 134.3 (1 C, d, J = 8.4, Ph–
Cq), 136.0 (2 C, d, J = 22.8, 2 Ph–CH), 140.9 (1 C, Ph–Cq), 141.5
Ph–◦Cq). 31P{ H} NMR (162 MHz; CDCl3) d -19.34. MS (FAB,
1
1
(1 C, Ph–Cq), 156.6 (1 C, Ph–Cq), 158.0 (1 C, Ph–Cq). 31P{ H}
120 C) m/z(rel%)=692(100, M+). HRMSfound:692.0671;calcd
NMR (162 MHz; CDCl3) d -21.5. MS (EI, 120 ◦C) m/z (rel%) =
808 (100, M+), 792 (53, M+ - O), 776 (13, M+ - 2O), 760 (11,
M+ - SO), 743 (98, M+ - Cp). HRMS found: 808.1596; calcd (for
20
(for C39H33Fe2OPS): 692.0690. [a]l = +60.6 (589 nm), +77.6
(578 nm), +188.6 (546 nm) (c = 0.50 in CHCl3). CD De (lmax) =
+29.9 (251 nm), +5.6 (310 nm), -1.7 (354 nm), +4.5 (476 nm) (c =
1.04 ¥ 10-3 mol L-1, CH2Cl2).
20
C45H45Fe2O3PS): 808.1528. [a]l = -14.4 (589 nm), -8.0 (578 nm),
+46.0 (546 nm) (c = 0.50, CHCl3). CD De (lmax) = +21.0 (252 nm),
-0.42 (291 nm), +5.3 (305 nm), -1.1 (355 nm), +2.8 (477 nm) (c =
9.65 ¥ 10-4 mol L-1, CH2Cl2).
(S,Sp,Sp)-2-Bis(3,5-dimethylphenyl)phosphino-2¢¢-(4-methyl-
phenyl)sulfinyl-biferrocene 8. Lithiated 6 (3 mmol) was re-
acted with chloro-bis(3,5-dimethylphenyl)phosphine (1.24 g,
4.5 mmol) in THF (20 mL). Chromatography: elution with
PE/acetone/Et3N (120/20/1) afforded (S,Sp,Sp)-8 as a yellow
solid (1.79◦g, 80%).
General procedure for the synthesis of the dichloropalladium
complexes (Sp,Sp)- [PdCl2(1)] and (Sp,Sp)-[PdCl2(4)] 10, 11
Mp 139 C. 1H NMR (400.1 MHz; CDCl3) d 2.19 (6 H, s, CH3),
2.35 (6 H, s, CH3), 2.45 (3 H, s, CH3), 3.77 (1 H, m, Cp–H), 3.92
(1 H, m, Cp–H), 4.18 (5 H, s, Cp¢–H), 4.23 (1 H, m, Cp–H), 4.25
(5 H, s, Cp¢–H), 4.47 (1 H, m, Cp–H), 4.69 (1 H, m, Cp–H), 5.04
(1 H, m, Cp–H), 6.71 (2 H, d, J = 7.4, Ph–H), 6.78 (1 H, s, Ph–H),
7.05 (1 H, s, Ph–H), 7.23 (2 H, d, J = 8.3, Ph–H), 7.34 (2 H, d,
Ligand 1 or 4 (0.1 mmol) in dry benzene (2 mL) was degassed and
transferred into a degassed solution of [PdCl2(CH3CN)2] (24.6 mg,
0.095 mmol) in benzene (2 mL). The resulting mixture was stirred
under Ar for 16 h at r.t. The precipitate was filtered off and dried
under vacuum to give complex [PdCl2(1)] or [PdCl2(4)].
J = 8.1, Ph–H), 7.79 (2 H, d, J = 8.1, Ph–H). 13C{ H} NMR
1
Dichloro-{(Sp,Sp)-[2,2¢¢-bis(diphenylphosphino-jP)-1,1¢¢-bifer-
rocene]} palladium(II) 10. (Sp,Sp)-[PdCl2(1)] (73 mg, 80%), red
(100.6 MHz; CDCl3) d 21.2 (2 C, 2 CH3), 21.4 (2 C, 2 CH3), 21.5
(1 C, CH3), 67.4 (1 C, Cp–CH), 68.6 (1 C, Cp–CH), 69.9 (1 C,
Cp–CH), 70.4 (5 C, Cp¢–CH), 70.9 (5 C, d, J = 1.5, 5 Cp¢–CH),
72.5 (1 C, d, J = 4.6, Cp–CH), 74.8 (1 C, d, J = 9.1, Cp–CH), 74.9
(1 C, d, J = 3.8, Cp–CH), 77.6 (1 C, d, J = 12.9, Cp–Cq), 87.9
(1 C, Cp–Cq), 88.2 (1 C, d, J = 25.1, Cp–Cq), 93.4 (1 C, Cp–Cq),
126.0 (2 C, 2 Ph–CH), 129.3 (2 C, 2 Ph–CH), 129.3 (1 C, Ph–CH),
129.7 (2 C, d, J = 17.5, 2 Ph–CH), 130.8 (1 C, Ph–CH), 133.3 (2 C,
d, J = 22.1, 2 Ph–CH), 137.3, 137.3, 137.4 (4 C, 4 Ph–C), 138.3
(1 C, d, J = 9.1, Ph–Cq), 139.4 (1 C, d, J = 9.9, Ph–Cq), 140.9
◦
prisms (from CHCl3/EtOH). Mp 230 C (dec). NMR: at 240 K
two conformers in a 5 : 1 ratio are observed, only the resonances
of the major conformer are given. 1H NMR (250 MHz, CD2Cl2,
240 K) d 3.47 (10 H, s, Cp¢–H), 3.55 (2 H, m, Cp–H), 4.41 (2 H,
m, Cp–H), 4.79 (2 H, m, Cp–H), 6.80 (2 H, br s, Ph–H), 7.23–
1
7.99 (16 H, m, Ph–H), 8.25 (2 H, br s, Ph–H). 13C{ H} NMR
(62.9 MHz, CD2Cl2, 240 K) d 70.0 (2 C, 2 Cp–CH), 70.6 (2 C, d,
J = 36.1, 2 Cp–C), 70.7 (10 C, Cp¢–CH), 72.3 (2 C, 2 Cp–CH), 78.7
(2 C, 2 Cp–CH), 85.3 (2 C, m, 2 Cp–C), 127.1 (4 C, m, 4 Ph–CH),
128.1 (2 C, m, 2 Ph–C), 129.0 (4 C, m, 4 Ph–CH), 129.9 (2 C, 2
Ph–CH), 132.2 (2 C, 2 Ph–CH), 133.2 (4 C, br m, 4 Ph–CH), 134.8
(2 C, dd, J = 3.7, J = 69.4, 2 Ph–C); 136.6 (4 C, br m, 4 Ph–CH).
(1 C, Ph–Cq), 141.5 (1 C, Ph–Cq). 31P{ H} NMR (162 MHz;
1
◦
CDCl3) d -20.0. MS (EI, 140 C) m/z (rel%) = 748 (89, M+),
733 (47, M+ - CH3), 683 (100, M+ - Cp). HRMS found: 748.1358;
1
1
31P{ H} NMR (162 MHz, CD2Cl2, 300K) d 27.8 (br s). 31P{ H}
20
calcd (for C43H41Fe2OPS): 748.1314. [a]l = -27.0 (589 nm), -20.6
NMR (162 MHz, CD2Cl2, 258 K) d 22.3 (major), 29.0 (minor).
(578 nm), +32.2 (546 nm) (c = 0.52 in CHCl3). CD De (lmax) =
+27.2 (252 nm), -0.9 (292 nm), +5.1 (308 nm), -1.2 (355 nm),
+3.16 (477 nm) (c = 8.82 ¥ 10-4 mol L-1 in CH2Cl2).
◦
20
MS (EI, 300 C) m/z (rel%) = 738 (M+ - PdCl2). [a]l = +658
(589 nm), +789 (578 nm), +1141 (546 nm) (c = 0.046 in CH2Cl2).
CD De (lmax) = -18.5 (240 nm), +43.2 (281 nm), +6.1 (331 nm),
+6.52 (511 nm) (c = 1.00 ¥ 10-4 mol L-1 in CH2Cl2).
(S,Sp,Sp)-2-Bis(3,5-dimethyl-4-methoxyphenyl)phosphino-2¢¢-
(4-methylphenyl)sulfinyl-1,1¢¢-biferrocene
9. Lithiated
6
(3 mmol) was reacted with chloro-bis(3,5-dimethylphenyl-4-
methoxyphenyl)phosphine (1.52 g, 4.5 mmol) in THF (20 mL).
Chromatography: elution with PE/acetone/Et3N (120/20/1)
afforded (S,Sp,Sp)-9 as a yellow solid (1.61 g, 66%).
Dichloro-{(Sp,Sp)-[2-bis(3,5-dimethyl-4-methoxyphenyl)phos-
phino-jP -2¢¢-bis[3,5-bis(trifluoromethyl)phenyl]phosphino-jP-
1,1¢¢-biferrocene]} palladium(II) 11. (Sp,Sp)-[PdCl2(4)] (110 mg,
84%), redneedles (from CH2Cl2/Et2O). Mp210 ◦C(dec). 1H NMR
(250 MHz, CD2Cl2, 260 K) d 2.25 (6 H, s, CH3 (A)), 2.31 (6 H, s,
CH3 (B)), 3.23 (1 H, m, Cp–H3), 3.56 (1 H, m, Cp–H3¢¢), 3.66 (3 H,
s, OCH3 (A)), 3.76 (3 H, s, OCH3 (B)), 3.97 (5 H, s, Cp¢–H), 4.08
(5 H, s, Cp¢¢¢–H), 4.35 (1 H, m, Cp–H4¢¢), 4.56 (1 H, m, Cp–H4),
4.90 (1 H, m, Cp–H5¢¢), 5.08 (1 H, m, Cp–H5), 7.34–7.48 (2 H, br
Mp 100 ◦C. 1H NMR (400.1 MHz; CDCl3) d 2.16 (6 H, s, CH3),
2.32 (6 H, s, CH3), 2.46 (3 H, s, CH3), 3.66 (3 H, s, OCH3), 3.75
(1 H, m, Cp–CH), 3.78 (3 H, s, OCH3), 3.93 (1 H, m, Cp–H), 4.17
(5 H, s, Cp¢–H), 4.23 (1 H, m, Cp–H), 4.25 (5 H, s, Cp¢–H), 4.46
(1 H, m, Cp–H), 4.68 (1 H, m, Cp–H), 5.02 (1 H, m, Cp–H), 6.72
2760 | Dalton Trans., 2009, 2751–2763
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d, Ar–H-ortho (B)), 7.57 (2 H, d, J = 13.0, Ar–H-ortho (A)), 7.95
(1 H, s, Ar–H-para (C)), 8.08 (1 H, s, Ar–H-para (D)), 8.21 (2 H,
d, J = 11.2, Ar–H-ortho (D)), 8.42 (2 H, d, J = 11.6, Ar–H-ortho
(C)). A, B: aryl rings 3,5-Me2-4-MeO-C6H2; C, D: aryl rings 3,5-
twice with EtOH (10 mL each). The orange-yellow solution was
filtered through Celite and after removal of the solvent under
reduced pressure [RuCl(p-cymene)((Sp,Sp)-1)]PF6 (68 mg, 87%,
soluble in acetone) was obtained as an orange solid.
1
(CF3)2-C6H3. 13C{ H} NMR (62.9 MHz, CD2Cl2, 260 K) d 15.9
Found: C 55.86, H 4.47. C54H50ClF6Fe2P3Ru requires C 56.2, H
4.38%. 1H NMR (400 MHz, CD3COCD3, 295 K) d 0.78 (3 H, s,
H15), 1.31 (3 H, d, JH–H = 6.9, H13), 1.4 (3 H, d, JH–H = 7.1, H14),
2.92 (1 H, spt, JH–H = 7.0, H12), 3.48 (1 H, m, Cp–H3), 3.63 (5 H,
s, Cp¢¢¢–H), 3.91 (5 H, s, Cp¢–H); 4.13 (1 H, m, Cp–H3¢¢), 4.46
(1 H, t, JH–H = 2.3, Cp–H4), 4.53 (1 H, t, JH–H = 2.7, Cp–H4¢¢),
5.25 (1 H, d, JH–H = 6.3, H8), 5.30 (1 H, m, Cp–H5), 5.34 (1 H,
m, Cp–H5¢¢), 5.96 (2 H, br s, H10 + H11), 6.18 (1 H, m, H7), 6.78
(2 H, br t, Ph–H), 7.13 (2 H, t, JH–H = 7.1, Ph–H), 7.34 (2 H, t,
JH–H = 7.3, Ph–H), 7.52 (2 H, t, JH–H = 6.9, Ph–H), 7.68 (8 H, m,
Ph–H), 8.08 (2 H, br t, Ph–H), 8.54 (2 H, br s, Ph–H). Assignment
of signal sets Cp–H/C1–5, Cp¢–H/C (ferrocene unit 1) and Cp–
H/C1¢¢–5¢¢, Cp¢¢¢–H/C (ferrocene unit 2) interchangeable. Some
(2 C, 2 CH3 (A)), 16.1 (2 C, 2 CH3 (B)), 59.7 (1 C, OCH3), 59.8
(1 C, OCH3), 70.4 (1 C, d, J = 8.7, Cp–C4¢¢), 70.8 (1 C, d, J = 9.6,
Cp–C4); 71.1 (5 C, Cp¢¢¢–C), 71.3 (5 C, Cp¢–C), 71.7 (1 C, Cp–C),
74.8 (1 C, d, J = 12.3, Cp–C3), 75.2 (1 C, Cp–Cq), 76.0 (1 C, d,
J = 11.0, Cp–C3¢¢), 76.9 (1 C, Cp–C5¢¢), 77.0 (1 C, Cp–C5), 85.3
(1 C, d, J = 10.5, Cp–Cq), 87.8 (1 C, d, J = 12.3, Cp–Cq), 121.8
(1 C, d, J = 67.6, MeO–Ph–C-meta), 122.8 (2 C, q, J = 272.2,
2 Ph–CF3), 122.9 (2 C, q, J = 272.2, 2 Ph–CF3), 124.1 (1 C, d,
J = 59.8, MeO–Ph–C-meta), 125.0–125.4 (2 C, br m, 2 CF3–Ph–
C-para (C + D)), 129.7–132.6 (8 C, Ph–Cq), 133.5 (2 C, br m, 2
CF3–Ph–C-ortho (C)), 134.3 (1 C, d, J = 12.8, CH3O–Ph–C-ortho
(B)), 134.6 (2 C, br m, 2 CF3–Ph–C-ortho (D)), 135.8 (2 C, br m,
2 CF3–Ph–C-ortho (C)), 159.3 (1 C, d, J = 3.8, MeO–Ph–C-para
(A)), 159.6 (1 C, d, J = 3.8, MeO–Ph–C-para (B)). A, B: aryl rings
1
of the signals are broad. 13C{ H} NMR (100.6 MHz, CD3COCD3,
295 K) d 13.4 (1 C, s, C15), 20.3 (1 C, s, C13), 21.9 (1 C, s, C14),
32.0 (1 C, s, C12), 68.3 (1 C, d, J = 8.3, Cp–C4), 70.1 (1 C, d,
J = 5.9, Cp–C4¢¢), 71.4 (5 C, s, Cp¢–C), 72.4 (5 C, s, Cp¢¢¢–C),
75.2 (1 C, d, J = 7.9, Cp–C3), 76.0 (1 C, d, J = 7.6, Cp–C5¢¢),
76.8 (1 C, d, J = 4.3, Cp–C3¢¢), 77.0 (1 C, s, Cp–C1¢¢), 77.3 (1 C,
s, Cp–C1), 77.4 (1 C, d, J = 9.2, Cp–C5), 77.8 (1 C, s, C6), 88.0
(1 C, d, J = 12.7, Cp–C2¢¢), 88.3 (1 C, d, J = 10.4, C10), 89.5
(1 C, d, J = 10.3, C8), 90.0 (1 C, d, J = 15.9, Cp–C2), 96.7 (1 C,
d, J = 2.7, C7), 97.2 (1 C, s, C9), 102.6 (1 C, d, J = 4.2, C11),
127.8 (2 C, d, J = 10.7, Ph–C-meta), 128.0 (2 C, d, J = 9.5, Ph–
C-meta), 128.0 (2 C, d, J = 10.3, Ph–C-meta), 128.2 (2 C, d, J =
10.3, Ph–C-meta), 130.0 (1 C, d, J = 2.5, Ph–C-para), 131.4 (1 C,
d, J = 2.6, Ph–C-para), 131.6 (2 C, pseudo t, Ph–C-para), 133.1
(1 C, dd, J = 52.3, J = 2.5, Ph–C-ipso), 133.1 (2 C, d, J = 9.3,
Ph–C-ortho), 135.3 (2 C, d, J = 10.8, Ph–C-ortho), 136.2 (1 C, dd,
J = 51.3, J = 2.6, Ph–C-ipso), 136.7 (4 C, br m, Ph–C-ortho), 138.3
(1 C, dd, J = 50.3, J = 2.2, Ph–C-ipso), 140.0 (1 C, d, J = 51.6,
1
3,5-Me-4-MeO-C6H2; C, D: aryl rings 3,5-(CF3)2-C6H3. 31P{ H}
NMR (162 MHz, CDCl3, 300K) d 21.5 [s, P-(3,5-Me2-4-MeO-
20
C6H2)2], 24.2 [s, P-(3,5-(CF3)2-C6H3)2]. [a]l = +1118 (589 nm),
+1287 (578 nm), +1741 (546 nm) (c = 0.043 in CHCl3). CD De
(lmax) = -2.2 (248 nm), +48.6 (279 nm), +6.3 (362 nm), +8.9
(459 nm), +13.9 (518 nm) (c = 1.00 ¥ 10-4 mol L-1 in CH2Cl2).
Bis(pentafluorophenyl)-{(Sp,Sp)-[2,2¢¢-bis(diphenylphosphino-
jP)-1,1¢¢-biferrocene]} palladium(II) 12. Ligand (Sp,Sp)-1 (50 mg,
0.068 mmol) was added to a solution of [Pd(C6F5)2(COD)]
(37.1 mg, 0.068 mmol) in CH2Cl2 (20 mL) and the mixture was
heated under reflux for 10 h. After cooling to r.t. the solvent was
removed under reduced pressure. The resulting solid was washed
withpentane(3¥5mL)anddriedundervacuum. Thefinalproduct
was obtained as an orange-red solid that was soluble in CH2Cl2
and CHCl3 (64 mg, 0.060 mmol, 88%).
Found: C 55.7, H 3.5. C56H36P2Fe2F10Pd·1.5H2O requires C
1
Ph–C-ipso). 31P{ H} NMR (161.9 MHz, CD3COCD3, 295 K) d
1
55.8, H 3.3%. H NMR (400 MHz, CDCl3, 293 K) d 3.8 (10 H,
-
-143.2 (spt, JFP = 707.5, PF6 ), 27.8 (d, JPP = 58.2), 33.2 (d, JPP
=
s, Cp–H), 4.02 (2 H, br s, Cp–H3), 4.34 (2 H, br t, Cp–H4), 4.65
(2 H, br s, Cp–H5), 7.2 (4 H, m, Ph–H), 7.32 (2 H, br t, Ph–H),
7.4 (6 H, br s, Ph–H), 7.5 (4 H, br s, Ph–H), 8.08 (4 H, br s,
58.2). 19F NMR (376.3 MHz, CD3COCD3, 295 K) d -73.0 (d,
JFP = 707.5, PF6 ). IR (KBr, cm-1): 1488.1, 1443.2, 1321.8, 1137.4,
-
-
1091.3, 840.4 (PF6 ), 707.25, 562.9, 496.9, 376. MS (FAB+) m/z =
1
Ph–H). 13C{ H} NMR (100.6 MHz, CDCl3, 293 K) d 69.8 (2 C,
-
-
1009 [M - (PF6 )]+, 875 [M - (PF6 ) - (C10H14)]+.
br s, Cp–CH), 71.0 (10 C, br s, Cp–CH), 73.2 (2 C, br s, Cp–
CH), 76.5 (2 C, br s, Cp–CH), 127.3 (4C, m, Ph–C-meta), 128.8
(4C, m, Ph–C-meta), 130.0 (2C, s, Ph–C-para), 131.7 (2C, s, Ph–C-
para), 133.0 (4C, br s, Ph–C-ortho), 135.7 (4C, br s, Ph–C-ortho).
Iodo-{(Sp,Sp)-[2,2¢¢-bis(diphenylphosphino-jP)-1,1¢¢-biferro-
cene]-(g6-p-cymene)} ruthenium(I) hexafluorophosphate 14.
Complex 14 was prepared as described for 13. (Sp,Sp)-1 (50 mg,
0.068 mmol); AgPF6 (17.1 mg, 0.068 mmol); [RuI2(p-cymene)]2
(33 mg, 0.034 mmol) in THF (35 mL). Product [RuI(p-
cymene)((Sp,Sp)-1)]PF6 (71 mg, 83%, soluble in acetone) was
obtained as a deep-red solid.
Found: C 52.4, H 4.2. C54H50F6Fe2IP3Ru requires: C 52.1, H 4%.
1H NMR (400 MHz, CD3COCD3, 295 K) d 0.55 (3 H, s, H15),
1.40 (3 H, d, JH–H = 7.0, H14), 1.44 (3 H, d, JH–H = 7.0, H13), 3.15
(1 H, m, Cp–H3), 3.62 (5 H, s, Cp¢¢¢–H), 3.63 (1 H, spt, JH–H = 7.0,
H12), 3.98 (5 H, s, Cp¢–H), 4.31 (1 H, m, Cp–3¢¢), 4.38 (1 H, td,
JH–H = 2.6, JH–P = 1.1, Cp–H4), 4.6 (1 H, t, JH–H = 2.6, Cp–H4¢¢),
5.30 (1 H, m, Cp–H5), 5.38 (1 H, m, Cp–H5¢¢), 5.59 (1 H, dd,
JH–H = 6.4, JH–P = 1.4, H8), 5.77 (2 H, br t, H11), 6.1 (2 H, br dd,
JH–H = 6.4, JH–P = 1.4, H10), 6.34 (1 H, JH–H = 4.9,br t, H7), 6.55
(2 H, br s, Ph–H), 6.95 (2 H, m, Ph–H), 7.22 (2 H, br td, Ph–H), 7.6
1
Signals for quaternary carbons have not been observed. 31P{ H}
NMR (161.9 MHz, CDCl3, 293 K) d 13.71 (2 P, s). 19F NMR
(376.3 MHz, CDCl3, 293 K) d -164.1 (2 F, m, F-meta), -163.0 (4
F, m, 2 F-meta + 2 F-para), -116.2 (2 F, m, F-ortho); -112.5 (2F,
m, F-ortho). Assignment based on COSY 19F–19F. MS (FAB+)
m/z = 1115 [M - (C5H5 ) + 2·H]+, 1011 [M - (C6F5 )]+, 844 [M -
-
-
(C6F5 ) - (C6F5)]+.
-
Chloro-{(Sp,Sp)-[2,2¢¢-bis(diphenylphosphino-jP)-1,1¢¢-bifer-
rocene]-(g6-p-cymene)} ruthenium(I) hexafluorophosphate 13.
Diphosphine (Sp,Sp)-1 (50 mg, 0.068 mmol) and AgPF6 (17.1 mg,
0.068 mmol) were added to a solution of [RuCl2(p-cymene)]2
(20.7 mg, 0.034 mmol) in THF (30 mL) and the mixture was heated
under reflux for 3 h. The resulting suspension was concentrated to
dryness under reduced pressure and the solid residue was treated
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(8 H, m, Ph–H), 7.75 (2 H, m, Ph–H), 8.4 (2 H, br s, Ph–H), 8.52
(2 H, br s, Ph–H). Assignment of signal sets Cp–H/C1–5, Cp¢–
H/C (ferrocene unit 1) and Cp–H/C1¢¢–5¢¢, Cp¢¢¢–H/C (ferrocene
(1C, d, J = 53.5, Ph–C-ipso), 140.9 (1C, d, J = 54.2, Ph–C-ipso).
1
31P{ H} NMR (161.9 MHz, CD3COCD3, 295 K) d -143.2 (spt,
JFP = 707.7, PF6 ), 28.1 (d, JPP = 63.6); 33.1 (d, JPP = 63.6). 19F
-
1
unit 2) interchangeable. Some of the signals are broad. 13C{ H}
NMR (376.308 MHz, CD3COCD3, 295 K) d -73.0 (d, JFP = 707.7,
PF6 ) IR (KBr, cm-1): 3431, 3088, 3052, 1705, 1480, 1439, 1306,
-
NMR (100.6 MHz, CD3COCD3, 295 K): d 12.7 (1 C, s, C15), 20.6
(1 C, s, C13), 23.2 (1 C, s, C14), 33.4 (1 C, s, C12), 67.9 (1 C, d, J =
9.2, Cp–C4), 70.3 (1 C, d, J = 6.3, Cp–C4¢¢), 71.2 (5 C, s, Cp¢–C),
72.8 (5 C, s, Cp¢¢¢–C), 74.2 (1 C, d, J = 7.8, Cp–C3), 76.4 (1 C,
d, J = 8, Cp–C5¢¢), 77.7 (1 C, dd, J = 40.6, J = 0.8, Cp–C1¢¢),
78.4 (1 C, d, J = 8.8, Cp–C5), 78.8 (1 C, d, J = 4.2, Cp–C3¢¢),
85.4 (1 C, dd, J = 54.0, J = 1.0, Cp–C1), 87.4 (1 C, d, J = 10.1,
C10), 89.0 (1 C, dd, J = 11.6, J = 1.1, Cp–C2¢¢), 89.4 (1 C, d, J =
9.7, C8), 90.4 (1 C, d, J = 16.2, Cp–C2), 96.5 (1 C, d, J = 2.9,
C7), 99.6 (1 C, s, C6), 100.7 (1 C, s, C9), 103.4 (1 C, d, J = 3.8,
C11), 127.4 (2 C, d, J = 10.5, Ph–C-meta), 127.7 (2 C, d, J = 9.6,
Ph–C-meta), 128.2 (2 C, d, J = 10.3, Ph–C-meta), 128.2 (2 C, d,
J = 9.9, Ph–C-meta), 129.5 (1 C, d, J = 2.5, Ph–C-para), 131.4
(1 C, d, J = 2.7, Ph–C-para), 131.5 (1 C, d, J = 2.6, Ph–C-para),
132.1 (1 C, d, J = 2.5, Ph–C-para), 132.4 (2 C, br m, Ph–C-ortho),
133.2 (2 C, d, J = 8.8, Ph–C-ortho), 133.3 (1 C, dd, J = 51.7, J =
3.0, Ph–C-ipso), 134.1 (1 C, dd, J = 50.8, J = 3.0, Ph–C-ipso),
135.2 (2 C, br m, Ph–C-ortho), 138.1 (1 C, dd, J = 52.1, J = 2.5,
Ph–C-ipso), 138.6 (2 C, br m, Ph–C-ortho), 142.3 (1 C, d, J =
-
-
1142, 1004, 840 (PF6 ), 748, 702, 559 (PF6 ), 492, 381. MS (FAB+)
m/z = 953 [M - (PF6 )]+, 875 [M - (PF6 ) - (C6H6)]+.
-
-
Iodo-{(Sp,Sp)-[2,2¢¢-bis(diphenylphosphino-jP)-1,1¢¢-biferro-
cene]-(g6-p-cymene)} ruthenium(I) iodide 16. Diphosphine
(Sp,Sp)-1 (142 mg, 0.192 mmol) was added to a solution of [RuI2(p-
cymene)]2 (94 mg, 0.096 mmol) in a 4 : 1 mixture of CH2Cl2 and
MeOH (5 mL). The resulting mixture was heated under reflux
with stirring for 3 h. After cooling the flask to r.t., the solvent
was removed under reduced pressure. The remaining solid was
washed with pentane (3 ¥ 15 mL), filtered off and dried. Product
[RuI(p-cymene)((Sp,Sp)-1)]I (201 mg, 85%, soluble in acetone) was
obtained as a red solid.
Found: C 52.6, H 4.2. C54H50Fe2I2P2Ru requires: C 52.84, H
1
4.11. H NMR (400 MHz, CD3COCD3, 295 K) d 0.54 (3 H, s,
H15), 1.40 (3 H, d, J = 7.0, H14), 1.43 (3 H, d, J = 7.0, H13),
3.14 (1 H, m, Cp–H3), 3.61 (5 H, s, Cp¢¢¢–H), 3.63 (1 H, spt, J =
7.0, H12), 3.97 (5 H, s, Cp¢–H), 4.30 (1 H, m, Cp–H3¢¢), 4.37
(1 H, td, JH–H = 2.6, JH–P = 1.0, Cp–H4), 4.59 (1 H, t, JH–H = 2.7,
Cp–H4¢¢), 5.29 (1 H, m, Cp–H5), 5.36 (1 H, m, Cp–H5¢¢), 5.56
(1 H, dd, JH–H = 6.3, JH–P = 1.5, H8), 5.76 (2 H, m, H11), 6.07
(2 H, dd, JH–H = 6.6, JH–P = 1.4, H10), 6.35 (1 H, t, JH–H = 5.6,
H7), 6.53 (2 H, br s, Ph), 6.97 (2 H, m, Ph), 7.22 (2 H, m, Ph),
7.60 (8 H, m, Ph), 7.74 (2 H, m, Ph), 8.36 (2 H, br s, Ph), 8.59
(2 H, br s, Ph). Assignment of signal sets Cp–H/C1–5, Cp¢–H/C
(ferrocene unit 1) and Cp–H/C1¢¢–5¢¢, Cp¢¢¢–H/C (ferrocene unit
1
50.2, Ph–C-ipso). 31P{ H} NMR (161.9 MHz, CD3COCD3, 295
-
K) d -143.2 (spt, JFP = 707.6, PF6 ), 27.5 (d, JPP = 53.8), 29.3 (d,
JPP = 53.8). 19F NMR (376.3 MHz, CD3COCD3, 295 K) d -73.0
(d, JFP = 707.6, PF6 ). IR (cm-1): 1482, 1436, 1409, 1092, 840.6
-
-
-
(PF6 ), 747.8, 701, 557 (PF6 ), 523, 491, 475, 447. MS (FAB+)
m/z = 1101 [M - (PF6 )]+, 967 [M - (PF6 ) - (C10H14)]+.
-
-
Chloro-{(Sp,Sp)-[2,2¢¢-bis(diphenylphosphino-jP)-1,1¢¢-biferro-
cene]-(g6-benzene)} ruthenium(I) hexafluorophosphate 15. Com-
plex 15 was prepared as described for 13. (Sp,Sp)-1 (50 mg,
0.068 mmol); AgPF6 (17.1 mg, 0.068 mmol); [RuCl2-
(C6H6)]2 (17 mg, 0.034 mmol) in THF (30 mL). Product [RuCl-
(C6H6)((Sp,Sp)-1)]PF6 (65 mg, 84%, soluble in acetone) was
obtained as a red solid.
1
2) interchangeable. Some of the signals are broad. 13C{ H} NMR
(100.6 MHz, CD3COCD3, 295 K) d 12.9 (1 C, s, C15), 20.8 (1 C,
s, C13), 23.4 (1 C, s, C14), 33.5 (1 C, s, C12), 67.9 (1 C, d, J =
9.2, Cp–C4), 70.3 (1 C, d, J = 6.2, Cp–C4¢¢), 71.2 (5 C, s, Cp¢–C),
72.8 (5 C, s, Cp¢¢¢–C), 74.2 (1 C, d, J = 7.6, Cp–C3), 76.4 (1 C,
d, J = 8.5, Cp–5¢¢), 77.7 (1 C, d, J = 40.8, Cp–C1¢¢), 78.4 (1 C,
d, J = 9.1, Cp–C5), 78.9 (1 C, d, J = 3.8, Cp–C3¢¢), 85.4 (1 C,
d, J = 54.2, Cp–C1), 87.3 (1 C, d, J = 10.4, C10), 89.0 (1 C, d,
J = 11.3, Cp–C2¢¢), 89.4 (1 C, d, J = 9.8, C8), 90.4 (1 C, d, J =
16.1, Cp–C2), 96.5 (1 C, d, J = 1.8, C7), 99.6 (1 C, s, C6), 100.6
(1 C, s, C9), 103.4 (1 C, d, J = 3.8, C11), 127.3 (2 C, d, J = 10.3,
Ph–C-meta), 127.6 (2 C, d, J = 9.6, Ph–C-meta), 128.2 (2 C, d, J =
10.5, Ph–C-meta), 128.2 (2 C, d, J = 10.2, Ph–C-meta), 129.5 (1 C,
d, J = 1.8, Ph–C-para), 131.3 (1 C, d, J = 2.6, Ph–C-para), 131.5
(1 C, d, J = 2.6, Ph–C-para), 132.0 (1 C, d, J = 2.3, Ph–C-para),
132.4 (2 C, br m, Ph–C-ortho), 133.1 (2 C, d, J = 9.2, Ph–C-ortho),
133.3 (1 C, dd, J = 51.7, J = 3.0, Ph–C-ipso), 134.1 (1 C, dd,
J = 50.8, J = 3.0, Ph–C-ipso), 135.2 (2 C, br m, Ph–C-ortho),
138.0 (1 C, dd, J = 52.1, J = 2.5, Ph–C-ipso), 138.6 (2 C, br m,
Found: C 54.24, H 4.03. C50H42ClF6Fe2P3Ru requires: C 54.67,
H 3.86. 1H NMR (400 MHz, CD3COCD3, 295 K) d 3.73 (1 H, m,
Cp–H3), 3.79 (5 H, s, Cp¢¢¢–H), 3.89 (5 H, s, Cp¢), 4.0 (1 H, m, Cp–
H3¢¢), 4.52 (1 H, t, JH–H = 2.6, Cp–H4¢¢), 4.55 (1 H, t, JH–H = 2.4,
Cp–H4), 5.35 (1 H, m, Cp–H5), 5.39 (1 H, m, Cp–H5¢¢), 5.79 (6 H,
s, C6H6), 6.92 (2 H, m, Ph–H), 7.19 (2 H, m, Ph–H), 7.39 (4 H, m,
Ph–H), 7.62 (10 H, m, Ph–H), 8.47 (2 H, br s, Ph–H). Assignment
of signal sets Cp–H/C1–5, Cp¢–H/C (ferrocene unit 1) and Cp–H/
C1¢¢–5¢¢, Cp¢¢¢–H/C (ferrocene unit 2) interchangeable, some of
1
the signals are broad. 13C{ H} NMR (100.6 MHz, CD3COCD3,
295 K) d 68.9 (1C, d, J = 8.1, CH–Cp), 70.3 (1C, d, J = 6.6,
CH–Cp), 71.8 (5C, s, CH–Cp), 72.6 (5C, s, CH–Cp), 74.8 (1C,
d, J = 41.4, CH–Cp), 75.7 (1C, d, J = 4.4, CH–Cp), 76.3 (1C,
d, J = 7.9, CH–Cp), 76.4 (1C, d, J = 7.0, CH–Cp), 76.6 (1C,
d, J = 8.7, CH–Cp), 76.9 (1C, d, J = 43.5, CH–Cp), 87.1 (1C,
d, J = 11.6, CH–Cp), 89.7 (1C, d, J = 15.4, CH–Cp), 97.4 (6C,
s, C6H6), 128.1 (4C, d, J = 10.5, Ph–C-meta), 128.2 (2C, d, J =
10.4, Ph–C-meta), 128.4 (2C, d, J = 10.0, Ph–C-meta), 130.2 (2C,
d, J = 2.3, Ph–C-para), 131.2 (4C, pt, Ph–C-para), 131.5 (2C, d,
J = 2.4, Ph–C-para), 132.0 (4C, d, J = 9.1, Ph–C-ortho), 133.7
(1C, d, J = 55.4, Ph–C-ipso), 135.1 (2C, br m, Ph–C-ortho), 135.8
(2C, br m, Ph–C-ortho), 138.6 (1C, d, J = 51.2, Ph–C-ipso), 139.8
1
Ph–C-ortho), 142.2 (1 C, d, J = 49.9, Ph–C-ipso). 31P{ H} NMR
(161.9 MHz, CD3COCD3, 295 K) d 27.56 (d, JPP = 53.9), 29.37
(d, JPP = 53.9). IR (cm-1): 1481.3, 1434.1, 1089.8, 828.2, 701.0,
491.7. MS (FAB+) m/z = 1101 [M - (I-)]+, 974 [M - 2·(I-)]+, 967
[M - (I-) - (C10H14)]+.
Standard procedure for hydrogenation reactions
The substrate (2.53 mmol) and the catalyst were dissolved
separately in the appropriate solvent (5 mL) under argon (total
2762 | Dalton Trans., 2009, 2751–2763
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volume: 10 mL) and the catalyst solution was stirred for 15 min.
For in situ reactions the metal source (1 equiv.) and the appropriate
amount of ligand (1.05, 2.1 or 2.2 equiv., for details see below)
were dissolved in the same solvent like the substrate and the
resulting solution was stirred for 15 min. Both the catalyst and
the substrate solutions were transferred through a steel capillary
into a 180 mL thermostated glass reactor or a 50 mL stainless
steel autoclave. The inert gas was then replaced by hydrogen (three
cycles) and the pressure was set. After completion of the reaction,
the conversion was determined by gas chromatography and the
product was recovered quantitatively after filtering the reaction
solution through a plug of silica. The enantiomeric purity of
the product was determined either by gas chromatography or by
HPLC.
diffusion of Et2O (1, 11), EtOH (10), or hexane (15) into solutions
of the corresponding complex in CH2Cl2 (11), CHCl3 (1, 10),
or acetone (15). Compound (Sp,Sp)-1 crystallized unsolvated.
Complex 10 formed an ordered solvate with two CHCl3 and
one H2O per bifep moiety. Complexes 11 and 15 crystallized in
the form of disordered solvates with unknown solvent content.
X-ray data were collected on Bruker Smart CCD area detector
diffractometers using graphite-monochromated Mo Ka radiation
˚
(l = 0.71073 A) and j- and w-scan frames covering complete
spheres of the reciprocal space. Corrections for absorption, l/2
effects, and crystal decay were applied.11 The structures were
solved by direct methods and refined on F2 with the program
suite SHELX-97.12 Anisotropic displacement parameters were
used for all non-hydrogen atoms. Hydrogen atoms were inserted in
idealized positions and were refined riding with the atoms to which
they were bonded. For complexes 11 and 15 the disordered solvent
was subjected to the SQUEEZE procedure in the PLATON
program prior to final refinement.13 In the case of complex 15
only a tiny crystal of weak scattering power was available; data
collection was therefore restricted to q = 23◦ and 5- and
6-membered rings were refined as idealized rigid groups. Crystal
data and experimental details are given in Table 1. Selected
geometric data are presented in Table 2. Further details are given in
the ESI.†
The following reaction conditions and methods for e.e. deter-
mination were applied:
MAC: 2.53 mmol (0.25 mol L-1) MAC; [Rh(NBD)2][BF4] +
1.05 equiv. ligand; s/c = 200; solvent: MeOH (10 mL); p(H2): 1
◦
◦
bar; 25 C; reaction time: 16 h; e.e.: GC, Chirasil-L-Val, 170 C,
isotherm.
MCA: 2.53 mmol (0.25 mol L-1) MCA; [Rh(NBD)2][BF4] + 1.05
equiv. ligand; s/c = 200; solvent: MeOH (10 mL); p(H2): 5 bar;
25 ◦C; reaction time: 15 h; e.e.: as methyl ester; HPLC; Chiralcel
OB, hexane–iPrOH: 98 : 2, 0.1 mL min-1.
PCA: 2.53 mmol (0.25 mol L-1) PCA; [Rh(NBD)2][BF4] + 1.05
equiv. ligand; s/c = 200; solvent: MeOH (10 mL); p(H2): 80 bar;
25 ◦C; reaction time: 14.5 h; e.e.: as methyl ester; HPLC; Chiralcel
OD-H, hexane–iPrOH: 97 : 3, 0.3 mL min-1.
Acknowledgements
This work was kindly supported by Solvias AG, Basel.
DMI: 2.53 mmol (0.25 mol L-1) DMI; [Rh(NBD)2][BF4] + 1.05
equiv. ligand; s/c = 200; solvent: MeOH (10 mL); p(H2): 1 bar;
25 ◦C; reaction time: 1 h; e.e.: GC, Lipodex E, 100 ◦C, isotherm.
EAA: 6.45 mmol (0.43 mol L-1) EAA; [RuI2(p-cymene)]2 + 2.2
equiv. ligand; s/c = 1000; solvent: EtOH (15 mL); additive: 1 N
HCl (aq.): 60 mL; p(H2): 80 bar; 80 ◦C; reaction time: 19–21 h; e.e.:
as trifluoroacetate derivative; GC, Lipodex E, 80 ◦C, isotherm.
EBA (ethyl benzoylacetate): 6.54 mmol (0.43 mol L-1) EBA;
[RuI2(p-cymene)]2 + 2.2 equiv. ligand; s/c = 1000; solvent: EtOH
(15 mL); additive: 1 N HCl (aq.): 60 mL; p(H2): 80 bar; 80 ◦C;
reaction time: 16–21 h; e.e.: HPLC, Chiralcel OD-H, hexane–
iPrOH: 99 : 1, 0.8 mL min-1.
ACA (acetylacetone): 6.45 mmol (0.43 mol L-1) ACA; [RuI2(p-
cymene)]2 + 2.2 equiv. ligand; s/c = 1000; solvent: EtOH (10 mL);
additive: 1 N HCl (aq.): 60 mL; p(H2): 80 bar; 80 ◦C; reaction time:
18–20 h; e.e.: as bis(trifluoroacetate) derivative; GC, Lipodex E,
80 ◦C, isotherm.
EPY (ethyl pyruvate): 2.53 mmol (0.25 mol L-1) EPY;
[RhCl(NBD)2]2 + 2.1 equiv. ligand; s/c = 100; solvent: toluene
(10 mL); p(H2): 40 bar; 25 ◦C; reaction time: 16 h; e.e.: GC, Lipodex
E, 80 ◦C, isotherm.
MEAI: 12.8 mmol (1.3 mol L-1) MEAI; [IrCl(COD)]2; + 2.1
equiv. ligand; s/c = 1000; solvent: toluene (10 mL); additives:
tetrabutylammonium iodide (2 equiv./Ir), CF3COOH (30 mL);
p(H2): 80 bar; 25 ◦C; reaction time: 15.5 h; e.e.: HPLC, Chiralcel
OD-H, hexane–iPrOH: 99.5 : 0.5; 1.0 mL min-1.
References
1 (a) R. Noyori, Adv. Synth. Catal., 2003, 345, 15–32; (b) S. A. Laneman,
in Handbook of Chiral Chemicals, ed. A. Ager, CRC Press LLC, Boca
Raton, 2nd edn., 2006, pp. 185–247; (c) H. Shimizu, I. Nagasaki, K.
Matsumura, N. Sayo and T. Saito, Acc. Chem. Res., 2007, 40, 1385–
1393.
2 (a) Y.-M. Li, F.-Y. Kwong, W.-Y. Yu and A. S. C. Chan, Coord.
Chem. Rev., 2007, 251, 2119–2144; (b) M. McCarthy and P. J. Guiry,
Tetrahedron, 2001, 57, 3809–3844; (c) For a list of chiral ligands see
Appendix to: Catalytic Asymmetric Catalysis, ed. I. Ojima, Wiley-
VCH, New York, 2000, pp. 802–856.
3 M. Sawamura, A. Yamauchi, T. Takegawa and Y. Ito, Chem. Commun.,
1991, 874–875.
4 (a) U. Nettekoven, M. Widhalm, P. C. J. Kamer, P. W. N. M. van
Leeuwen, K. Mereiter, M. Lutz and A. L. Spek, Organometallics, 2000,
19, 2299–2309; (b) U. Nettekoven, M. Widhalm, H. Kalchhauser, P. C.
J. Kamer, P. W. N. M. van Leeuwen, M. Lutz and A. L. Spek, Org.
Chem., 2001, 66, 759–770.
5 L. Xiao, K. Mereiter, F. Spindler and W. Weissensteiner, Tetrahedron:
Asymmetry, 2001, 12, 1105–1108.
6 D. Guillaneux and H. B. Kagan, J. Org. Chem., 1995, 60, 2502–
2505.
7 PCMODEL, v. 8.5, Serena software, Bloomington, US.
8 H. Shanan-Atidi and K. H. Bar-Eli, J. Phys. Chem., 1970, 74, 961–
963.
9 R. C. Fuson, and E. A. Cleveland, Organic Syntheses, Wiley, New
York, 1955, Coll. vol. 3, pp. 339–340.
10 M. A. Bennet and A. K. J. Smith, J. Chem. Soc., Dalton Trans., 1974,
233–241.
11 Bruker programs: SMART, v. 5.629; SAINT, v. 6.45; SADABS, v. 2.10;
XPREP, v. 6.1; SHELXTL, v. 6.14 Bruker AXS Inc., Madison, WI,
2003.
X-Ray structure determination
12 G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Crystallogr., 2008,
Crystals of (Sp,Sp)-1, (Sp,Sp)-[PdCl2(1)] (10), (Sp,Sp)-[PdCl2(4)]
(11), and (Sp,Sp)-[RuCl(C6H6)(1)]PF6 (15) were obtained by slow
64, 112–122.
13 A. L. Spek, J. Appl. Crystallogr., 2003, 36, 7–13.
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