Palladium complexes with metallocene-bridged bidentate diphosphine ligands: Synthesis, structure, and catalytic activity in amination and cross-coupling reactions

Article abstract of DOI:10.1021/om050869w

The syntheses and characterization of series of new metallocene-bridged diphosphines and the structures of complexes of some of them with Pd(II) are reported. These complexes were examined as the catalysts in amination reactions of halogenoarenes and in the Suzuki reaction. The complexes based on ruthenocene (2) and osmocene (3) showed lower activities then the palladium complex with dppf in amination reactions and the same activities in the Suzuki reaction. New palladium complexes with the bidentate bulky and electron-rich ligands Fe(η⁵-C₅H₄P(o-PrⁱC ₆H₄)₂)₂ (6) and Feη⁵- C₅H₄P(o-MeOC₆H₄)₂) ₂ (5) showed a very high catalytic activity in amination and Suzuki coupling of aryl bromides. A complex with ligand 6 was used in the amination of 4-bromotoluene by primary and secondary amines and showed excellent activity.

Full text of DOI:10.1021/om050869w

2750
Organometallics 2006, 25, 2750-2760
Palladium Complexes with Metallocene-Bridged Bidentate
Diphosphine Ligands: Synthesis, Structure, and Catalytic Activity
in Amination and Cross-Coupling Reactions
Oleg V. Gusev,† Tat’yana A. Peganova,† Alexander M. Kalsin,† Nikolai V. Vologdin,†
Pavel V. Petrovskii,† Konstantin A. Lyssenko,† Aleksey V. Tsvetkov,‡ and
Irina P. Beletskaya*,‡
A. N. NesmeyanoV Institute of Organoelement Compounds of the Russian Academy of Sciences,
VaViloV St. 28, 119991 Moscow, Russian Federation, and Department of Chemistry, M. V. LomonosoV
Moscow State UniVersity, Leninskie Gory, 119992 Moscow, Russian Federation
ReceiVed October 7, 2005
The syntheses and characterization of series of new metallocene-bridged diphosphines and the structures
of complexes of some of them with Pd(II) are reported. These complexes were examined as the catalysts
in amination reactions of halogenoarenes and in the Suzuki reaction. The complexes based on ruthenocene
(2) and osmocene (3) showed lower activities then the palladium complex with dppf in amination reactions
and the same activities in the Suzuki reaction. New palladium complexes with the bidentate bulky and
electron-rich ligands Fe(η5-C5H4P(o-PriC6H4)2)2 (6) and Fe(η5-C5H4P(o-MeOC6H4)2)2 (5) showed a very
high catalytic activity in amination and Suzuki coupling of aryl bromides. A complex with ligand 6 was
used in the amination of 4-bromotoluene by primary and secondary amines and showed excellent activity.
complexes with Pd(II). The catalytic activity of these complexes
was studied in two types of reactions: amination of aryl bromide
and Suzuki-Miyaura coupling.
Introduction
New phosphine ligands, bidentate chelate phosphine ligands
in particular, have attracted constant attention because of their
crucial role in defining the catalytic activity of transition-metal
complexes. Relatively small changes in their electronic or spatial
structure, or “bite angle” (in complexes), often produce dramatic
effects on the reaction catalyzed by the corresponding complex.
These effects revealed themselves most vividly in the amination
reactions of aryl halides (Buchwald-Hartwig reaction), the
application of bidentate phosphine ligands being of pivotal
importance on the early stage of its development.1-4 Metal-
containing ligands and particularly those based on a ferrocene
scaffold have played a very important role in many organic
transformations catalyzed by palladium complexes.5-10
Results and Discussion
Synthesis of the Phosphine Ligands M(η5-C5H4PPh2)2 (1,
M ) Fe; 2, M ) Ru; 3, ) Os), Fe(η5-C5Me4PPh2)2 (4), Fe-
(η5-C5H4PR2)2 (5, R ) o-MeOC6H4; 6, R ) o-PriC6H4; 7, R
) o-MeC6H4; 8, R ) Et; 9, R ) C6F5; 10, R ) OEt) and
Their Complexes. The metallocene-bridged diphosphines [M(η5-
C5H4PPh2)2] (1, M ) Fe; 2, M ) Ru; 3, M ) Os) and [Fe(η5-
C5Me4PPh2)2] (4) and the corresponding Pd complexes were
prepared according to the procedures reported earlier.11-22
In this paper we report the synthesis of series of new metal-
containing bidentate phosphine ligands and the structures of their
(11) Gusev, O. V.; Kalsin, A. M.; Peterleitner, M. G.; Petrovskii, P. V.;
Lyssenko, K. A.; Akhmedov, N. G.; Bianchini, C., Oberhauser, W.; Meli,
A. Organometallics 2002, 21, 3637.
* To whom correspondence should be addressed. E-mail:
beletska@org.chem.msu.ru. Tel/Fax: +7-095-9393618.
† A. N. Nesmeyanov Institute of Organoelement Compounds of the
Russian Academy of Sciences.
(12) Butler, I. R.; Cullen, W. R.; Kim, T.-J.; Rettig, S. J.; Trotter, J.,
Organometallics 1985, 4, 972.
(13) Brown, J. M.; Guiry, P. J. Inorg. Chim. Acta 1994, 220, 249.
(14) Stang, P. J.; Olenyuk, B.; Fan, J.; Arif, A. M. Organometallics 1996,
15, 904.
‡ M. V. Lomonosov Moscow State University.
(1) Wagaw, S.; Rennels, R. A.; Buchwald, S. L. J. Am. Chem. Soc. 1997,
119, 8451.
(2) Yang, B. H.; Buchwald, S. L. J. Organomet. Chem. 1999, 576, 125.
(3) Hartwig, J. F. Handbook of Organopalladium Chemistry for Organic
Synthesis; Negishi, E., Ed.; Wiley-Interscience: New York, 2002; Vol. 1,
p 1051.
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M.; Pellinghelli, M. A. J. Organomet. Chem. 1994, 481, 173.
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K. J. Am. Chem. Soc. 1994, 116, 4221.
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Leeuwen, P. W. N. M. Eur. J. Inorg. Chem. 1998, 155.
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(9) Beller, M.; Magerlein, W.; Indolese, A. F.; Fischer, C. Synthesis 2001,
7, 1098.
(18) Sato, M.; Shigeta, H.; Sekino, M.; Akabori, S. J. Organomet. Chem.
1993, 458, 199 and references therein.
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(20) Li, G.; Tan, A. L.; Yip, W.-H.; Mak, T. C. W.; Hor, T. S. A. J.
Chem. Soc., Dalton Trans. 1996, 4315.
(21) Li, S.; Wei, B.; Low, P. M. N.; Lee, H. K.; Hor, T. S. A.; Xue, F.;
Mak, T. C. W. J. Chem. Soc., Dalton Trans. 1997, 1289.
(22) (a) Gusev, O. V.; Kalsin, A. M.; Petrovskii, P. V.; Lyssenko, K.
A.; Oprunenko, Yu. F.; Bianchini, C.; Meli, A.; Oberhauser, W. Organo-
metallics 2003, 22, 913. (b) Quin, L. D. A Guide to Organophosphorus
Chemistry; Wiley-Interscience: New York, 2000; p 213, and references
therein.
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10.1021/om050869w CCC: $33.50 © 2006 American Chemical Society
Publication on Web 04/20/2006

Pd Complexes with Metallocene-Bridged Diphosphines
Organometallics, Vol. 25, No. 11, 2006 2751
Scheme 1
Scheme 4
Scheme 2
1
signals at δ -36.0, -44.4, and -58.7, respectively. In the H
NMR spectra of 7, 5, and 9 the Cp rings were characterized by
two signals for HR and Hâ. Methyl and methoxy groups for 7
and 5 were observed as singlets at δ 2.45 and 3.75, respectively.
In the 19F{1H} NMR spectrum of 9 three signals at δ -51.8,
-82.1, and -71.6 arose from o-F, m-F, and p-F of the
pentafluorophenyl rings. This implies fast rotation of the
substituted phenyl rings in 7, 5, and 9. Analogous conclusions
can be drawn from the 13C{1H} NMR spectra of 5 and 9.
In the 31P{1H} NMR spectrum of the o-isopropylphenyl-
substituted compound 6 there is one sharp singlet at δ -40.1.
The Cp rings are characterized by two signals of HR and Hâ
protons at δ 4.07 and 4.36 in the 1H NMR spectrum and by the
signals at δ 71.72, 73.30, and 78.36 in the 13C{1H} NMR
spectrum, which is evidence for a symmetric ferrocene moiety.
The carbons of the phenyl rings are also characterized by one
set of signals at δ 125.06, 125.11, 128.73, 133.98, 136.61, and
152.32. At the same time the signals of the isopropyl groups in
the 1H NMR spectrum were observed as two doublets at δ 0.92
and 1.30 for the methyls and as a broadened multiplet at δ 3.88
for the CH groups, which implied inequivalence of the isopropyl
groups. Two sets of signals for the isopropyl groups were
observed in the 13C{1H} NMR spectrum as well: δ 23.65, 23.97
(Me) and δ 30.90, 31.15 (CH). The signals of the methyl groups
Scheme 3
The synthesis of new ferrocene-based ligands was carried out
by two alternative pathways. 1,1′-Bis(bis(o-methoxyphenyl)-
phosphino)ferrocene (5) was obtained by the reaction of bis-
(o-methoxyphenyl)chlorophosphine23 with 1,1′-dilithioferrocene4,24
(Scheme 1).
However, the same method cannot be applied for the synthesis
of a ligand with o-isopropylphenyl substituents at the phospho-
rus. In a reaction with the sterically congested chlorophosphine
ClP(o-PriC6H4)2, only the diphosphine monoxide (o-PriC6H4)2P-
P(dO)(o-PriC6H4)2 and ferrocene were isolated, presumably due
to reduction of chlorophosphine by dilithioferrocene with the
formation of a P-P bond and further oxidation of one
phosphorus atom (during isolation).25 Therefore, the o-isopro-
pylphenyl-substituted ligand [Fe(η5-C5H4P{o-PriC6H4}2)2] (6)
was synthesized by treatment of 1,1′-bis(dichlorophosphino)-
ferrocene with o-PriC6H4Li in 68% yield (Scheme 2). This
method was also used for the synthesis of Fe(η5-C5H4PR2)2 (7,
R ) o-MeC6H4; 8, R ) Et; 9, R ) C6F5).
1
in the H NMR spectrum did not collapse upon heating the
sample of 6 in toluene-d8 up to 100 °C. However, exchange
between these two isopropyl groups was observed by selective
saturation of one of the methyl signals in 1H NMR, resulting in
a simultaneous decrease of signal for the second methyl group.
This exchange proceeded slowly on the NMR time scale,
perhaps due to the need for concerted rotation of the bulky ortho-
substituted aryl rings around C-P bonds.
Reactions of the ligands 1-10 with [Pd(PhCN)2Cl2] lead to
formation of the dichloride complexes [M(η5-C5H4PPh2)2PdCl2]
(11, M ) Fe; 12, M ) Ru; 13, ) Os), [Fe(η5-C5Me4PPh2)2-
PdCl2] (14), and [Fe(η5-C5H4PR2)2PdCl2] (15, R ) o-MeOC6H4;
16, R ) o-PriC6H4; 17, R ) o-MeC6H4; 18, R ) Et; 19, R )
C6F5; 20, R ) OEt) in near-quantitative yields (Scheme 4).
Structural and spectral data for the complexes 11-14 have
been published earlier.11,22,26 Coordination of the ethyl- and
ethoxy-substituted ligands 8 and 10 with PdCl2 affects the
signals of the diastereotopic protons of the CH2 groups
differently. Thus, the ethoxy groups in complex 20 were
presented as a triplet at δ 1.36 and broadened multiplet at δ
The ligand [Fe(η5-C5H4P{OEt}2)2] (10) was obtained by
treatment of 1,1′-bis(dichlorophosphino)ferrocene with ethanol
and pyridine (Scheme 3).
It is worth noting that the ligands 5-10 were synthesized in
high yields and can easily be purified. All the compounds
obtained were characterized by spectroscopy and by elemental
analysis.
In the 1H NMR spectrum of 8 the CH2 groups were observed
at δ 1.59 as a broadened multiplet, while for 10 two signals at
δ 3.75 and 3.89 arose from the methylene groups due to
diastereotopicity of the CH2 protons. Chemical shifts and
coupling constants for the other signals in the H and 31P{1H}
1
spectra of 8 and 10 were similar to those of related diphosphines.
In 31P NMR spectra the o-tolyl- (7), o-anisyl- (5), and penta-
fluorophenyl-substituted (9) ligands were characterized by sharp
(23) McEwen, W. E.; Beaver, B. D. Phosphorus Sulfur Relat. Elem. 1985,
24, 259.
(24) Burk, M.; Gross, M. F. Tetrahedron Lett. 1994, 50, 9363.
(25) Brady, F. J.; Cardin, C. J.; Cardin, D. J.; Wilcock, D. J. Inorg. Chim.
Acta 2000, 298, 1.
(26) Bianchini, C.; Oberhauser, W.; Meli, A.; Parisel, S.; Gusev, O. V.;
Kalsin, A. M.; Vologdin, N. V.; Dolgushin, F. M. J. Mol. Catal. A 2004,
224, 35.

2752 Organometallics, Vol. 25, No. 11, 2006
Table 1. Selected Geometrical Parameters for 13, 15, 16, and 18
GuseV et al.
11 (M ) Fe)
12 (M ) Ru)
13 (M ) Os)
15 (M ) Fe)
16 (M ) Fe)
18 (M ) Fe)
M-CCp, Å
1.994-2.055
1.629
1.632
2.282
2.300
2.347
2.349
97.98(2)
89.96(4)
1.804
1.796
1.818-1.826
0.019
0.032
6.2
34.1
21.6
2.129(5)-2.225(5)
1.811(5)
1.800(5)
2.298(1)
2.305(1)
2.331(1)
2.351(1)
101.29(4)
88.19(4)
1.804(5)
1.796(5)
1.818(5)-1.826(5)
-0.002
2.005(6)-2.065(7)
1.638(6)
1.638(7)
2.2744(15)
2.2619(15)
2.3524(15)
2.3609(15)
100.27(5)
90.22(5)
1.809(6)
1.825(5)
1.797(7)-1.823(7)
0.167
2.018(7)-2.064(7)
1.653(7)
1.636(7)
2.292(2)
2.318(2)
2.342(2)
2.345(2)
101.54(7)
88.74(7)
1.768(7)
1.802(7)
1.840(8)-1.856(7)
0.033
2.019(4)-2.067(4)
1.645(4)
1.645(4)
2.2742(9)
2.2727(9)
2.3713(9)
2.3615(9)
97.74(3)
87.05(3)
1.788(4)
1.805(4)
1.826(4)-1.834(4)
0.0519
M-X(1),a Å
M-X(2),b Å
Pd(1)-P(1), Å
Pd(1)-P(2), Å
Pd(1)-Cl(1), Å
Pd(1)-Cl(2), Å
P(1)-Pd(1)-P(2), deg
Cl(1)-Pd(1)-Cl(2), deg
P(1)-C(1), Å
P(1)-C(6), Å
P-CPh, Å
2.305f
2.358f
100.02(2)
90.14(2)
δ
δ
P(1),c Å
P(2),c Å
-0.048 f
-0.018
0.1824
3.1
9.3
0.1
-0.189
7.1
31.4
40.6
0.0842
0.58
25.6
5.7
Cp/Cp,d deg
9.2
39.3
8.9
31.7
26.8
θ,e deg
Pd(1)-P(1)-P(2)/
M-P(1)-P(2), deg
P(1)-Pd(1)-Cl(2)/
P(2)-Pd(1)-Cl(1), deg
6.2
2.5
1.4
20.8
5.5
a Centroid of the C(1)-C(5) Cp ring. b Centroid of the C(6)-C(7) Cp ring. c Deviation of the phosphorus atom from the Cp plane ring. A negative value
means that P(1)/P(2) is closer to Os/Fe. d The dihedral angle between the two Cp rings. A positive value means that the Cp rings are inclined toward the Pd.
e The torsion angles C(1)-X(1)-X(2)-C(6), where C(1) and C(6) are the carbon atoms bonded to the P and X is the centroid. f The average value according
to: Nataro, C.; Campbell, A. N.; Ferguson, M. A.; Incarvito, C. D.; Rheingold, A. L. J. Organomet. Chem. 2003, 673, 47.
Chart 1
by pairs of broadened signals at δ 4-5. The signals of the ortho
protons of the phenyls in 15 and 17 were broad and were shifted
downfield. The signal of the ortho fluorines in 19 was also
broadened and appeared at δ -46.1 in the 19F{1H} NMR
spectrum.
The NMR spectra for 15 and 17 were also recorded at low
temperature. The signal of 15 in the 31P{1H} NMR spectrum
becomes sharper upon cooling to -80 °C, although the
phosphorus atoms remain equivalent. In the 1H NMR spectrum
of 15 at -50 °C two different MeO groups were observed, even
though the signals were still rather broad. However, its 1H NMR
spectrum at -80 °C was well resolved and consisted of two
inequivalent MeO groups at δ 3.30 and 3.87 and four Cp protons
at δ 4.02, 4.08, 4.16, and 4.67; aryl protons were observed in
the region δ 6.7-9.2. The appearance at lower temperatures of
two different aryl substituents at one phosphorus is apparently
evidence for the relatively slow rotation of the aryl rings around
C-P bonds.
The 31P{1H} NMR spectrum of the tolyl-substituted complex
17 recorded at -50 °C showed the presence of two isomers of
the symmetrical structure A (singlet at δ 48.83) and unsym-
metrical structure B (two doublets at δ 33.46 and 38.46) in the
ratio 2.7:1 (Chart 1). The amount of symmetric isomer increases
on lowering the temperature, reaching the ratio 5.8:1 at -80
°C. The presence of ortho substituents in the aryl rings of 15,
17, and 19 leads to slower interconversion between symmetrical
(A) and unsymmetrical isomers (B) in comparison with the case
for complexes containing unsubstituted phenyls, [M(η5-C5H4-
PPh2)2PdCl2] (11, M ) Fe; 12, M ) Ru; 13, ) Os).11,22,26 Thus,
complexes 15 and 17 exist as a mixture of two isomers, which
at room temperature are in a dynamic equilibrium.
In the 31P{1H} NMR spectrum of the o-isopropyl-substituted
complex 16 two doublets at δ 38.1 and 41.0 arose, which was
evidence for its unsymmetrical structure. In the 1H NMR
spectrum eight methyl signals (δ -0.07 to +1.74) and four CH
groups (δ 1.92-3.57) were observed; these signals arose from
the inequivalent isopropyl substituents. The eight broadened
singlets in the region δ 4.10-5.45 were assigned to the protons
of the Cp rings. Thus, according to the NMR data the structure
of 16 in solution does not have any elements of symmetry.
1
4.33 in the H NMR spectrum and as singlets at δ 16.04 and
65.48 in the 13C{1H} NMR spectrum, while a doublet of triplets
at δ 1.35 and two multiplets at δ 2.20 and 2.50 in the 1H NMR
spectrum and a singlet at δ 9.65 and a multiplet with an ABX
pattern22b at δ 22.45 in the 13C{1H} NMR spectrum arose from
the ethyl groups in 18. In 31P{1H} NMR both complexes 18
and 20 have one singlet each at δ 42.46 and 119.96, cor-
respondingly. Their ferrocene moieties in 1H NMR spectra were
observed as pairs of singlets at δ 4.50, 4.53 and at δ 4.55, 4.63
for 18 and 20, respectively. In the 13C{1H} NMR spectra these
moieties have signals at δ 72.71 (t), 72.39 (t), 74.95 (m) and at
δ 72.63 (t), 73.62 (t), 75.05 (dd) for 18 and 20, respectively.
In the 31P{1H} NMR spectra of the dichloride palladium
complexes with ortho-substituted aryl groups 15, 17, and 19
recorded at room temperature were observed broadened signals
X-ray Structures of Palladium Complexes 13, 15, 16, and
18. The crystal structures of the complexes 13, 15, 16, and 18
have been determined by X-ray diffractometry (Table 1). For
1
at δ 40.15, 40.22, and 11.50, respectively. In the H NMR
spectra ferrocene moieties of 15, 17, and 19 were characterized

Pd Complexes with Metallocene-Bridged Diphosphines
Organometallics, Vol. 25, No. 11, 2006 2753
Figure 1. ORTEP drawings of 13. Thermal ellipsoids are drawn at the 50% probability level. The bottom drawing gives a projection on
the plane of the cyclopentadienyl rings.
purposes of comparison Table 1 contains structure data of
complexes 1112,27,28 and 12,29 which allows us to evaluate the
effect of the metal on the metallocene bridge (Figures 1-4).
Palladium in complexes 11-13 has nearly a square-planar
configuration. The Cp rings in the metallocene moieties have
staggered conformations with twist angles of 31.7-39.3° for
11-13. The deviations of palladium from the plane P-M-P
are 21.6 and 26.8° for 11 and 13, respectively. Changes in the
M-Cpcenter distance going from 1.634 Å (11) to 1.80 Å (12) to
1.81 Å (13) results in an increase of the bite angle P-Pd-P:
97.98(2)° (11), 100.02(2)° (12), and 101.29(4)° (13).
Substituents at the phosphorus in 15, 16, and 18 define the
structures of these complexes (Figures 2-4).
The structure of the sterically congested o-anisyl complex
15 differs significantly from that for 11. Palladium still has a
square-planar configuration (the dihedral angle Cl(1)-Pd-P(1)/
(28) De Lima, G. M.; Filgueiras, C. A. L.; Giotto, M. T. S.; Mascarenhas,
Y. P. Transition Met. Chem. 1995, 20, 380.
(27) Hayashi, T.; Konishi, M.; Kobori, Y.; Kumada, M.; Higuchi, T.;
Hirotsu, K. J. Am. Chem. Soc. 1984, 106, 158.
(29) Nataro, C.; Campbell, A. N.; Ferguson, M. A.; Incarvito, C. D.;
Rheingold, A. L. J. Organomet. Chem. 2003, 673, 47.

2754 Organometallics, Vol. 25, No. 11, 2006
GuseV et al.
Figure 2. ORTEP drawings of 18. Thermal ellipsoids are drawn
at the 50% probability level. The bottom drawing gives a projection
on the plane of the cyclopentadienyl rings.
Cl(2)-Pd-P(2) is 1.4°); it lies almost on the plane P-Fe-P
(the P-Fe-P/P-Pd-P angle is 0.1°), which leads to an increase
of the bite angle P-Pd-P to 100.27(5)°.
Further increase in the steric bulkiness of the aryl ortho
substituent in the o-isopropylphenyl complex 16 results in more
dramatic changes in the structure. The palladium has a config-
uration significantly distorted from square planar (the angle Cl-
(1)-Pd-P(1)/Cl(2)-Pd-P(2) is 20.8°); the palladium atom
deviates from the P-Fe-P plane by 40.6°. The bite angle
increases to 101.54(7)°, though the Fe-Cpcenter distances are
1.636(7) and 1.653(7) Å, which are close to those in 11 and
15.
Figure 3. ORTEP drawings of 15. Thermal ellipsoids are drawn
at the 50% probability level. The bottom drawing gives a projection
on the plane of the cyclopentadienyl rings.
It is thought that Pd(II) is rapidly reduced to Pd(0) in the
t-BuONa-amine system. This is supported by the fact that the
Pd(0)-BINAP complex was much less active than complexes
15 and 16.
The comparison of activity demonstrates that the efficiency
of the catalyst decreases in the triad (η5-Cp′)2M(PPh2)2 when
Fe is substituted by Ru, in agreement with the results reported
by Hartwig,4 or Os. Little difference was found between ligands
containing Ru and Os. When Cp* (Cp* ) tetramethylcyclo-
pentadiene) was used instead of Cp (dppf analogue 4), a
significant increase in the yield was observed (63% in 20 min).
Complexes having ethyl (18), ethoxy (20), and pentafluorophen-
yl groups (19) at the phosphorus atom turned out to be
ineffective (entries 6, 8, and 7). As expected, the complex with
ligand 7, having o-tolyl groups at the phosphorus atom, showed
higher activity (entry 5) than the complex with dppf (62%
compared to 42%). However, complexes with phosphine ligands
5 and 6, containing o-methoxyphenyl and o-isopropylphenyl
substituents, respectively, were found to be much more active.
With these complexes 100% conversion in the reaction is
The ethyl-substituted complex 18 has a structure similar to
that of a complex with dppf, 11. The palladium atom has nearly
a square-planar configuration (the dihedral angle Cl(1)-Pd-
P(1)/Cl(2)-Pd-P(2) is 5.5°); the palladium atom deviates from
the plane P-Fe-P by -5.7°, the Cp rings are staggered (25.6°),
and the bite angle P-Pd-P is 97.74(3)°.
Catalytic Properties of Pd Complexes with Ligands 1-10
in the Amination of Aryl Halides. The catalytic activity of
Pd complexes with ligands 1-10 was studied in the amination
of 4-bromotoluene by morpholine as a model reaction using 1
mol % of catalyst in dioxane (Scheme 5). The data (Table 2)
allow us to compare the effect of the central metal Fe, Ru, or
Os on ligands 1-3 and to evaluate the influence of the R group
on the diphosphinoferrocene complexes 15-20.

Pd Complexes with Metallocene-Bridged Diphosphines
Organometallics, Vol. 25, No. 11, 2006 2755
Table 2. Amination of 4-Bromotoluene with Morpholine
Catalyzed by Palladium Complexes with Ligands 1-10
reacn
time
temp,
°C
yield of N-(4-methylphenyl)
entry
ligand
morpholine,a %
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
2
3
4
7
8
9
10
20 min
20 min
20 min
20 min
20 min
20 min
20 min
20 min
5 min
5 min
5 min
20 h
100
100
100
100
100
100
100
100
100
100
100
20
42b
8
12
63b
62
16
13
1-2
99b
99b
59
6
5
6
BINAPc
5
6
1
20 h
20 h
20 h
20
20
20
18
0
0
BINAPc
a Yields determined by 1H NMR with acetylferrocene as a standard
relative to bromotoluene. b Isolated yield. c Pd(dba)2/BINAP (1:1).
Scheme 6
Scheme 7
Figure 4. ORTEP drawings of 16. Thermal ellipsoids are drawn
at the 50% probability level. The bottom drawing gives a projection
on the plane of the cyclopentadienyl rings.
Amination reactions are more complex than any other cross-
coupling reactions, leading to the formation of carbon-carbon
or carbon-heteroatom bonds.1-4 This fact is related to the
different requirements for the acid-base properties of amine
at different stages of the catalytic cycle: there is still much
uncertainty about the nature of the catalytic cycle itself, as well
as its rate-limiting step, which is presumably the reductive
elimination step, unlike the case for other cross-coupling
reactions.
The catalytic cycle shown in Scheme 7, which involves ligand
substitution by amine, resulting in an increased N-H bond
acidity in the coordinated complex, has an equally appropriate
alternative (Scheme 8), in which the amide complex is formed
by the nucleophilic attack of amine at the alkoxide complex.
It is well-known that the reduction of the C-Hal bond in
aryl halides is usually the main side process competing with
the amination reactions (see the catalytic cycle). To study such
selectivity, we measured the ArNR′R′′/ArH ratio in the reaction
of 4-bromobiphenyl with morpholine (Scheme 9). Since 4-bro-
mobiphenyl is a more reactive substrate than 4-bromotoluene,
the yields were determined after 10 min (Table 3). The Pd
Scheme 5
achieved in 5 min (entries 9 and 10). Moreover, the above
complexes are more active than complexes with dppf and even
with BINAP (entries 1 and 11). Apparently, this can be
explained by steric factors, which in this case play a major role.
According to Hartwig4 the electronic influence of a methoxy
group in a para position (4-anisyl) of a ferrocene-based ligand
in amination reactions is insignificant. Ligands 5 and 6 showed
some catalytic activity even at room temperature (entries 12
and 13), while BINAP and dppf were not active under these
conditions (entries 14 and 15).
The complex with ligand 6 also allowed the amination of an
activated aryl chloride with a modest yield and even of p-tolyl
chloride, though the yield was poor (Scheme 6).

2756 Organometallics, Vol. 25, No. 11, 2006
GuseV et al.
Scheme 8
Scheme 10
Table 4. Amination of 4-Bromotoluene by Various Amines
Catalyzed by Complex 16
Scheme 9
Table 3. Amination of 4-Bromobiphenyl by Morpholine
Catalyzed by Palladium Complexes with 1-10
yield of N-
1
a Yields determined by H NMR with acetylferrocene as a standard.
(4-biphenyl)-
yield of
approx ratio
ArNR1R2/ArH
entry
ligand
morpholine,a %
biphenyl,a %
Scheme 11
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
48
18
24
60
98
97
57
22
12
11
5
5
5
4
2
2
3
10
1
8
10
4
5
15
49
48
14
2
12
<2
Thus, complexes based on ligands 5 and 6 are new, highly
efficient catalysts for the amination of aryl bromides. The high
activity of their complexes as well as the high selectivity
displayed in amination reactions are in accord with the views
that chelate ligands, especially sterically hindered ones, promote
amination and hamper the process of â-hydride elimination.
Catalytic Activity of Pd Complexes with Ligands 1-10
in Suzuki-Miyaura Coupling between 4-Tolyl Bromide and
(4-Methoxyphenyl)boronic Acid.30 Though Suzuki type cross-
coupling reactions do not require the presence of bidentate
phosphine ligands, the latter are sometimes applied in this
reaction.31 We have shown that all complexes described above
are active in the reaction of 4-bromotoluene with (4-methoxy-
phenyl)boronic acid and in all cases the coupling product is
formed quantitatively (Scheme 11). Therefore, the relative
activities of these complexes were determined by comparing
the yields of the coupling product after 10 min (Table 5).
We found that, in contrast to the case for amination, the nature
of the metal in the metallocene has practically no effect on the
complex activitysalmost equal yields (60-69% in 10 min) were
obtained for all the triad 1-3. The addition of eight methyl
groups to the cyclopentadienyl rings of dppf (ligand 4) leads to
an increase of the complex activity (yield 84%), as was observed
in the amination reaction. Though complexes 18-20 are less
active than dppf, they are effective in Suzuki coupling and show
similar activities, which shows that the Suzuki reaction is much
10
10
a Yield determined by LC relative to ArBr.
complex with 1 demonstrates in this reaction higher activity
than do the complexes with 2 and 3 (entries 1-3), in the same
way as in the reaction of 4-bromotoluene, and the amount of
reduction product is noticeable (10-20% relative to amination
product). For poorly effective complexes with ligands 8-10
the yield of the reduction product is comparable to that of the
amination product. One can see that even with ligands 1 and 4
(entries 1 and 4) the yield of ArH is far from negligible.
However, for the most active complexes 15 and 16, the yield
of amination product is close to quantitative (entries 5 and 6).
These results are in agreement with previous observations4
that the ArNR1R2/ArH ratio grows with an increase of the
P-Pd-P bite angle in catalytic complexes (compare 100.27°
for 15 and 101.54° for 16 with 97.74° for 18). However, the
bite angle is obviously not the only factor governing the catalytic
activity, since in the Fe, Ru, Os triad an opposite trend is
observed (compare 97.98° (Fe) with 100.02° (Ru) and 101.29
(Os)). Even though the structure data have not been obtained
for the catalytically active Pd(0) complexes, but for their
precursors, we suppose that the most important structural
features, including the bite angles, are retained in the corre-
sponding Pd(0) complexes or at least follow the same trend.
(30) (a) Miyaura, N.; Suzuki, A. Chem. ReV. 1995, 95, 2457. (b) Miyaura,
N. Top. Curr. Chem. 2002, 219, 11. (c) Miura, M. Angew. Chem., Int. Ed.
2004, 43, 2201.
(31) (a) Shen, W. Tetrahedron Lett. 1997, 38, 5575. (b) Saton, Y.; Gude,
C.; Chan, K.; Firooznia, F. Tetrahedron Lett. 1997, 38, 7645. (c) Franc,
C.; Denonne, F.; Cuisinier, C.; Ghosez, L. Tetrahedron Lett. 1999, 40, 4555.
(d) Ali, N. M.; McKillop, A.; Mitchel, M. B.; Rebelo, R. A.; Wallbank, P.
J. Tetrahedron 1992, 48, 8117.
Using the complex PdCl2-6 as the best catalyst for the
amination reaction, we carried out the reactions of 4-bromo-
toluene with different types of amines (Scheme 10). The results
are presented in Table 4. All reactions are usually complete
within 5-30 min. In the case of primary amines monoarylation
is sometimes accompanied by diarylation.

Pd Complexes with Metallocene-Bridged Diphosphines
Organometallics, Vol. 25, No. 11, 2006 2757
Table 5. Suzuki Coupling of 4-Bromotoluene with
4-(Methoxyphenyl)boronic Acid Catalyzed by Palladium
Complexes with Ligands 1-10a
obtained was warmed to room temperature, stirred overnight, and
then refluxed for 3 h. The solvent was removed under reduced
pressure. The residue was washed with hexane (2 × 20 mL) and
then dissolved in hot benzene (100 mL). The resulting solution was
passed through a column (8 cm × 2 cm) of silica, which then
washed with benzene until the washings became colorless. The
solution thus obtained was concentrated to 10 mL, affording a
yellow precipitate of the product, which was filtered off, washed
with benzene (5 mL) and hexane (10 mL), and dried under vacuum.
Yield: 2.05 g (55%). Anal. Calcd for C38H36FeO4P2: C, 67.67; H,
5.38. Found: C, 67.74; H, 5.44. 1H NMR (CDCl3): δ 3.75 (s, 12H,
OMe), 3.96 (s, 4H, C5H4), 4.39 (s, 4H, C5H4), 6.80-7.25 (m, 16H,
o-C6H4OMe). 31P{1H} NMR (CDCl3): δ -44.4 (s). 13C{1H} NMR
(CDCl3): δ 55.43 (s, OMe), 72.48 (s, â-C, C5H4), 73.64 (d, J )
15.3 Hz, R-C, C5H4), 75.55 (d, J ) 6.4 Hz, ipso-C, C5H4), 109.96
(s, C6H4), 120.25 (s, C6H4), 127.02 (d, J ) 11.2 Hz, ipso-C(P),
C6H4), 129.65 (s, C6H4), 133.98 (s, C6H4), 160.67 (d, J ) 17.3 Hz,
ipso-C(OMe), C6H4).
yield of 4-methyl-4′-
yield of 4-methyl-4′-
ligand
methoxybiphenyl,b %
ligand
methoxybiphenyl,b %
1
2
3
4
5
60
63
69
84
100
6
7
8
9
10
100 (99)c
83
50
52
44
a Conditions: aqueous dioxane, K2CO3, 100 °C. b Yields determined by
1H NMR with acetylferrocene as a standard. c Isolated yield.
less sensitive to the nature of the catalyst than the amination
reaction. As in the amination reaction the activities of complexes
with ligands 4 and 7 are equal, and both are more active than
complexes with ligands 1-3 and 8-10.
However, the highest activity was observed, as in the
amination reaction, for complexes with ligands 5 and 6. Using
these complexes allows us to carry the reaction to completion
in 10 min and to obtain 4-methoxy-4′-methylbiphenyl selectively
in quantitative yield.
It is worth noting that the reason complexes 15 and 16 always
have the highest activity in such different types of reactions is
not clear. These reactions are thought to have different rate-
determining steps. While in the amination reaction an increase
of the bite angle would facilitate the reductive elimination,32
which is thought to be the rate-determining step, the same
increase does not favor Suzuki coupling, where oxidative
addition and transmetalation are more important.
Synthesis of Fe(η5-C5H4P{o-C6H4Pri}2)2 (6). A solution of
o-LiC6H4Pri was prepared as follows. Lithium wire (0.70 g, 100
mmol) was placed under an argon atmosphere in a three-necked
flask, upon which Et2O (50 mL) was added. A solution of o-BrC6H4-
Pri (10.0 g, 50.3 mmol) in Et2O (20 mL) was added dropwise
through a dropping funnel for 1 h to allow the slow reflux of ether.
The mixture was stirred overnight, and the solution was decanted
through a cannula to give a solution of o-LiC6H4Pri in Et2O (60
mL, 0.78 M, 46.8 mmol). To the solution of aryllithium obtained
was added a solution of Fe(η5-C5H4PCl2)2 (4.10 g, 10.6 mmol) in
Et2O (60 mL) dropwise at 0 °C. The mixture was warmed, stirred
overnight, and then refluxed for 2 h. The resulting mixture was
quenched with MeOH (2 mL), and the solvent was evaporated.
The residue was dissolved in hexane (100 mL), filtered through a
short bed of silica, and concentrated to 10 mL. The precipitated
yellow crystals were filtered off, quickly washed with hexane (10
mL), and dried under vacuum. Yield: 5.2 g (68%). Anal. Calcd
Conclusions
Palladium complexes with the bulky and electron-rich bi-
dentate ligands Fe(η5-C5H4P(o-PriC6H4)2)2 (6) and Fe(η5-C5H4P-
(o-MeOC6H4)2)2 (5) showed a very high catalytic activity in
amination and Suzuki coupling and allow us to perform the
reaction with nonactivated aryl bromides in a very short time,
with high selectivity and product yield.
1
for C46H52FeP2: C, 76.45; H, 7.25. Found: C, 76.21; H, 7.24. H
NMR (CDCl3): δ 0.92 (d, 6H, J ) 6.7, CH(CH3)2), 1.30 (d, 6H,
J ) 6.7, CH(CH3)2), 3.88 (dq, J1 ) 13.8, J2 ) 6.7 Hz, CH(CH3)2),
4.07 (s, 4H, C5H4), 4.36 (s, 4H, C5H4), 6.95-7.25 (m, 16H, o-C6H4-
Pri). 31P{1H} NMR (CDCl3): δ -40.1 (s). 13C{1H} NMR
(CDCl3): δ 23.65 (s, Me), 23.97 (s, Me), 30.90 (s, CHPr), 31.15
(s, CHPr), 71.72 (d, J ) 3.5 Hz, â-C, C5H4), 73.30 (d, J ) 13.2 Hz,
R-C, C5H4), 78.36 (d, J ) 9.1 Hz, ipso-C, C5H4), 125.09 (d, J )
4.4, C6H4), 125.35 (s, C6H4), 128.73 (s, C6H4), 133.98 (s, C6H4),
136.64 (d, J ) 11.6 Hz, ipso-C(P), C6H4), 152.32 (d, J ) 24.4 Hz,
ipso-C(Pri), C6H4).
Experimental Section
General Procedures. All experiments were performed under
1
argon in solvents purified by standard methods. H, 31P{1H}, 19F-
{1H}, and 13C{1H} NMR spectra were recorded on Bruker AMX
400 and Varian VXR 400 spectrometers. Chemical shifts are
reported in ppm (δ) with reference to TMS as an internal standard
(1H and 13C{1H} NMR spectra), and CF3COOH for 19F{1H} NMR
or 85% H3PO4 for 31P{1H} NMR spectra as an external standards.
Microanalyses were performed at the A. N. Nesmeyanov Institute
of Organoelement Compounds. The following compounds were
synthesized according to published procedures: ClP(o-C6H4-
OMe)2,23 Fe(η5-C5H4PCl2)2,33 [PdCl2(PhCN)2].34
Synthesis of Fe(η5-C5H4P{o-C6H4Me}2)2 (7). The solution of
o-LiC6H4Me was prepared as follows. Lithium wire (1.54 g, 220
mmol) was placed under an argon atmosphere in a three-necked
flask, whereupon Et2O (50 mL) was added. A solution of o-BrC6H4-
Me (9.4 g, 6.6 mL, 55 mmol) in Et2O (20 mL) was added dropwise
through a dropping funnel for 1 h to allow slow reflux of ether.
The mixture was stirred overnight, and the solution was decanted
through a cannula to give a solution of o-LiC6H4Me in Et2O (60
mL, 0.85 M, 51.0 mmol). To the solution of aryllithium (11.8 mL,
10 mmol) obtained was added a solution of Fe(η5-C5H4PCl2)2 (1.00
g, 2.6 mmol) in Et2O (70 mL) dropwise at 0 °C. The mixture was
warmed, stirred overnight, and then refluxed for 2 h. The resulting
mixture was quenched with MeOH (2 mL), and the solvent was
evaporated. The residue was dissolved in benzene (100 mL) and
the solution filtered through a short bed of silica. The filtrate was
evaporated, and the yellow crystals obtained were dried under
vacuum. Yield: 1.09 g (69%). 1H NMR (CDCl3): δ 2.45 (s, 12H,
Me), 4.07 (s, 4H), 4.28 (s, 4H), 7.05 (m, 16H, C6H4). 31P{1H} NMR
(CDCl3): δ -36.00 (s).
Synthesis of Fe(η5-C5H4P{o-C6H4OMe}2)2 (5). To a solution
of ferrocene (1.02 g, 5.5 mmol) in hexane/Et2O (30/30 mL) cooled
to 0 °C was added a solution of n-BuLi (1.45 M, 9.1 mL, 13.0
mmol) following the addition of TMEDA (2.0 mL, 13.0 mmol).
The solution was warmed to room temperature and was stirred for
20 h to afford a slurry of 1,1′-dilithioferrocene. The reaction mixture
was cooled to 0 °C, and a solution of ClP(o-C6H4OMe)2 (3.0 g,
12.0 mmol) in Et2O (50 mL) was added. The solution/slurry
(32) van Leeuwen, P. W. N. M.; Kamer, P. C. J.; Reek, J. N. H.; Dierkes,
P. Chem. ReV. 2000, 100, 2741
(33) Reetz, M. T.; Gosberg, A.; Goddard, R. Chem. Commun. 1998, 19,
2077.
Synthesis of [Fe(η5-C5H4PEt2)2] (8). A solution of EtMgBr (1.21
M, 23.4 mL, 28.4 mmol) was added dropwise at 0 °C to a stirred
(34) Doyle, J. R.; Slade, P. E.; Jonassen, H. B. Inorg. Synth. 1960, 6,
218.

2758 Organometallics, Vol. 25, No. 11, 2006
GuseV et al.
solution of Fe(η5-C5H4PCl2)2 (1.85 g, 4.77 mmol) in Et2O (50 mL).
The mixture was warmed and stirred for 3 h. The resulting mixture
was quenched with degassed water (2 mL); the solvent was then
removed under vacuum, and the solid was dissolved in benzene
(100 mL). This solution was filtered through a short bed of silica.
The solvent was evaporated, and the residue was dried under
vacuum. Yield: 1.36 g (80%). 1H NMR (CDCl3): δ 1.06 (m, 12H,
Me), 1.59 (m, 8H, CH2), 4.18 (s, 4H, C5H4), 4.26 (s, 4H, C5H4).
31P{1H} NMR (CDCl3): δ -26.1 (s).
47.7 Hz), 41.0 (d, 1P, J ) 47.7 Hz). 13C{1H} NMR (CD2Cl2): δ
22.75 (s, Me), 23.28 (s, Me), 24.6 (s, 5Me), 26.81 (s, Me), 30.73
(s, CHPr), 32.53 (s, CHPr), 34.68 (s, CHPr), 35.38 (s, CHPr), 70.39
(s, C5H4), 71.49 (s, C5H4), 72.22 (s, 2C, C5H4), 73.69 (s, C5H4),
75.15 (s, C5H4), 77.3 (s, C5H4), 78.37 (s, C5H4), 81.70 (d, ipso-C,
C5H4, J ) 48.3 Hz), 85.6 (d, ipso-C, C5H4, J ≈ 20 Hz), 130.00 (m,
18C), 140.58 (d, ipso-C(P), C6H4, J ) 27 Hz), 142.22 (d, ipso-
C(P), C6H4, J ) 27 Hz), 150.86 (d, ipso-C(Pri), C6H4), 151.84 (s,
ipso-C(Pri), C6H4), 152.89 (s, ipso-C(Pri), C6H4), 154.07 (s, ipso-
C(Pri), C6H4).
Synthesis of Fe(η5-C5H4P{C6F5}2)2 (9). To a solution of
pentafluorobenzene (4.30 g, 25.5 mmol) in Et2O (60 mL) cooled
to -78 °C was added a solution of n-BuLi (1.96 M, 13.0 mL, 25.5
mmol). The reaction mixture was stirred at this temperature for 1
h, and then a solution of Fe(η5-C5H4PCl2)2 (2.47 g, 6.36 mmol) in
Et2O (40 mL) was added dropwise. The resulting solution was
slowly warmed to room temperature and was stirred overnight. The
mixture was quenched with MeOH (2 mL); the solvent was then
removed under vacuum, and the solid was dissolved in hexane (60
mL). This solution was filtered through a glass frit, concentrated
to 10 mL, and placed in a refrigerator for 3 days. The yellow
precipitate was obtained, the mother liquor was decanted, and the
solid was washed quickly with cold hexane (10 mL) and dried.
Yield 4.6 g (79%). Anal. Calcd for C34H8F20FeP2: C, 44.67; H,
0.88. Found: C, 44.64; H, 0.88. 1H NMR (CDCl3): δ 4.29 (s, 4H,
C5H4), 4.42 (s, 4H, C5H4). 31P{1H} NMR (CDCl3): δ -58.7
(quintet, J(P-F) ) 30.5 Hz). 19F{1H} NMR (CDCl3): δ -82.1
(br. t, 8F, J ) 20 Hz, m-F(C6F5)), -71.6 (t, 4F, J ) 20.5 Hz,
p-F(C6F5)), -51.8 (t, 8F, J ) 28 Hz, o-F(C6F5)). 13C{H} NMR
(CDCl3): δ 68.61 (s, ipso-C, C5H4), 72.95 (d, J ) 4.9 Hz, â-C,
C5H4), 74.53 (d, J ) 19.7 Hz, R-C, C5H4), 108.77 (m, J1 + J2 )
37.2 Hz, C6F5), 147.25 (d, J ) 275 Hz, C6F5), 137.58 (dt, J1 )
254, J2 ) 14 Hz, C6F5), 142.50 (dt, J1 ) 256, J2 ) 12.5 Hz, C6F5).
Synthesis of [Fe(η5-C5H4P{OEt}2)2] (10). A solution of EtOH
(1.24 mL, 21.6 mmol) and pyridine (1.75 mL, 21.6 mmol) in hexane
(50 mL) was added dropwise at 0 °C to a solution of Fe(η5-C5H4-
PCl2)2 (2.04 g, 5.26 mmol) in hexane (150 mL). The mixture was
warmed, stirred for 1 h, filtered through a glass frit, and placed in
a refrigerator for 1 day. The precipitate of pyridinium chloride was
filtered off, the resulting solution was evaporated, and the residue
was dried under vacuum. Yield: 1.96 g (87%). 1H NMR (CDCl3):
δ 1.21 (t, 12H, J ) 7 Hz, Me), 3.72 (m, 4H, CH2), 3.87 (m, 4H,
CH2), 4.36 (s, 4H, C5H4), 4.39 (s, 4H, C5H4). 31P{1H} NMR
(CDCl3): δ 157.82 (s).
Synthesis of [{Fe(η5-C5H4P{o-C6H4Me}2)2}PdCl2] (17). Simi-
larly, complex 17 was synthesized from 7 as yellow crystals.
Yield: 0.48 g (74%) Anal. Calcd for C34H8F20FeP2PdCl2‚
1
0.5C6H6: C, 59.56; H, 4.75. Found: C, 59.61; H, 4.60. H NMR
(CDCl3): δ 1.45 (s, 6H, Me), 3.37 (s, 6H, Me), 4.10 (s, 2H, C5H4),
4.21 (s, 2H, C5H4), 4.28 (s, 2H, C5H4), 4.32 (C, 2H), 7.38 (m, 14H,
C6H4), 9.12 (m, 2H, o-H, C6H4). 31P{1H} NMR (CDCl3, -50 °C):
δ 48.84 (s), 38.46 (d, J ) 33.2 Hz), 33.47 (d, J ) 33.2 Hz).
Synthesis of [{Fe(η5-C5H4P{C6F5}2)2}PdCl2] (19). Similarly,
complex 19 was synthesized from 9 (0.74 g, 0.81 mmol) and [Pd-
(PhCN)2Cl2] (0.30 g, 0.78 mmol) as purple crystals. Yield: 0.73 g
(86%). Anal. Calcd for C34H8F20FeP2PdCl2: C, 37.41; H, 0.74.
Found: C, 37.56; H, 0.71. 1H NMR (CDCl3): δ 4.42 (s, 4H, C5H4),
4.72 (s, 4H, C5H4). 31P{1H} NMR (CDCl3): δ 11.5 (br s). 19F{1H}
NMR (CDCl3): δ -81.0 (t, 8F, J ) 20 Hz, m-F(C6F5)), -67.5 (t,
4F, J ) 20.5 Hz, p-F(C6F5)), -46.1 (br m, 8F, o-F(C6F5)). 13C{H}
NMR (CDCl3): δ 73.09 (s, â-C, C5H4), 77.21 (s, R-C, C5H4), 84.25
(m, ipso-C, C5H4, J1 + J2 ) 67.0 Hz, C6F5), 106.75 (m, ipso-C6F5),
146.95 (d, o-C6F5, J ) 247 Hz), 138.21 (d, m-C6F5, J ) 255 Hz),
144.49 (d, p-C6F5, J ) 245 Hz).
Synthesis of [Fe(η5-C5H4PEt2)2PdCl2] (18). A solution of [Pd-
(PhCN)2Cl2] (0.75 g, 1.96 mmol) in benzene (30 mL) was added
to a solution of 8 (0.75 g, 2.07 mmol) in benzene (50 mL). A
precipitate readily formed in a few minutes, and the mixture was
stirred overnight. Red-brown crystals of 18 were filtered off, washed
with benzene, and dried under vacuum. Yield: 0.94 g (89%). Anal.
Calcd for C18H28FeP2PdCl2: C, 40.07; H, 5.23. Found: C, 38.46;
1
H, 5.01. H NMR (CDCl3): δ 1.35 (dt, J1 ) 18.6, J2 ) 7.6 Hz,
12H, Me), 2.19 (m, 4H, 2CH2), 2.51 (m, 4H, 2CH2), 4.50 (s, 4H),
4.53 (s, 4H). 31P{1H} NMR (CDCl3): δ 42.50 (s). 13C{1H} NMR
(CDCl3): δ 9.65 (Cs, Me), 22.44 (m, CH2, J1 + J2 ) 35.0 Hz),
72.71 (t, â-C, C5H4, J ) 3.2), 73.39 (t, R-C, C5H4, J ) 4.4 Hz),
74.95 (m, ipso-C, C5H4, J1 + J2 ) 56.8 Hz).
Synthesis of [Fe(η5-C5H4PAr2)2PdCl2] (15). General Proce-
dure. A solution of [Pd(PhCN)2Cl2] (0.46 g, 1.20 mmol) in benzene
(30 mL) was added to a solution of 5 (0.83 g, 1.23 mmol) in
benzene (50 mL). A precipitate readily formed in a few minutes,
and the mixture was stirred overnight. Red-brown crystals of 15
were filtered off, washed with benzene, and dried under vacuum.
Yield: 0.98 g (96%). Anal. Calcd for C38H36FeO4P2PdCl2: C,
Synthesis of [Fe(η5-C5H4P(OEt)2)2PdCl2] (20). A solution of
[Pd(PhCN)2Cl2] (0.65 g, 1.68 mmol) in benzene (30 mL) was added
to a solution of 10 (0.71 g, 1.68 mmol) in benzene (50 mL). The
mixture was stirred overnight, and the solvent was then removed
under vacuum. The solid was dissolved in benzene (10 mL), and
then 50 mL of Et2O was added to give pale yellow crystals. This
crystals were filtered off, washed with Et2O, and dried under
vacuum. Yield: 0.79 g (78%). Anal. Calcd for C18H28FeO4P2-
1
53.58; H, 4.23. Found: C, 53.68; H, 4.26. H NMR (CDCl3): δ
1
3.62 (s, 12H, OMe), 4.12 (s, 4H, C5H4), 4.47 (s, 4H, C5H4), 7.00
(d, 4H, J ) 7.8 Hz, o-C6H4OMe), 7.03 (t, 4H, J ) 7.2 Hz, o-C6H4-
OMe), 7.55 (t, 4H, J ) 7.8 Hz, o-C6H4OMe), 8.08 (m, 4H, o-C6H4-
OMe). 31P{1H} NMR (CDCl3): δ 40.1 (s).
PdCl2: C, 35.82; H, 4.68. Found: C, 35.94; H, 4.68. H NMR
(CDCl3): δ 1.36 (t, 12H, J ) 6.94 Hz, Me), 4.33 (m, 8H, CH2),
4.54 (s, 4H, C5H4), 4.62 (s, 4H, C5H4). 31P{1H} NMR (CDCl3): δ
119.93 (s).13C{1H} NMR (CDCl3): δ 16.10 (t, CH3, J ) 3.2 Hz),
65.50 (t, CH2, J ) 2.5 Hz), 72.63 (t, â-C, C5H4, J ) 7.0 Hz), 73.62
(t, R-C, C5H4, J ) 4.8 Hz), 75.05 (dd, ipso-C, C5H4, J1 ) 2.8, J2
) 94.8 Hz).
Catalytic Amination of 4-Bromotoluene with Morpholine.
4-Bromotoluene (117 mg 0.684 mmol), morpholine (75 mg, 0.850
mmol), sodium tert-butoxide (81 mg, 0.850 mmol), and 1 mol %
of palladium catalyst were stirred in dioxane (2.5 mL) under reflux
for an appropriate time. The reaction mixture was treated with water
and extracted twice with CH2Cl2. The organic layer was then dried
over Na2SO4 and concentrated in vacuo. The product was purified
by flash chromatography on silica gel, with a hexane/benzene/
diethyl ether (6:1:1) mixture as eluent. Yield of N-(4-methylphenyl)-
Synthesis of [{Fe(η5-C5H4P{o-C6H4Pri}2)2}PdCl2] (16). Com-
plex 16 was prepared analogously from 6 (0.96 g, 1.33 mmol) and
[Pd(PhCN)2Cl2]] (0.50 g, 1.30 mmol) as brown crystals. Yield: 0.98
g (84%). Anal. Calcd for C46H52FeP2PdCl2: C, 61.39; H, 5.82.
1
Found: C, 61.58; H, 5.79. H NMR (CDCl3): δ -0.07 (s, 3H,
Me), 0.00 (s, 3H, Me), 0.42 (s, 3H, Me), 0.83 (s, 3H, Me), 1.18 (s,
3H, Me), 1.31 (s, 3H, Me), 1.74 (s, 6H, 2Me), 1.92 (s, 1H,
CH(CH3)2), 2.82 (s, 1H, CH(CH3)2), 3.34 (s, 1H, CH(CH3)2), 3.57
(s, 1H, CH(CH3)2), 4.10 (s, 2H, C5H4), 4.19 (s, 1H, C5H4), 4.32 (s,
1H, C5H4), 4.57 (s, 1H, C5H4), 4.91 (s, 1H, C5H4), 5.45 (s, 2H,
C5H4), 6.3-7.7 (br m, 14H, C6H4), 9.02 (br m, 1H, H1(C6H4)), 9.59
(br m, 1H, H1(C6H4)). 31P{1H} NMR (CDCl3): δ 38.1 (d, 1P, J )

Pd Complexes with Metallocene-Bridged Diphosphines
Organometallics, Vol. 25, No. 11, 2006 2759
Table 6. Crystallographic Data for Complexes 13, 15, 16, and 18
13
15
16
18
formula
C
34H28Cl2OsP2Pd‚
C
38H36Cl2FeO4P2Pd‚
C
46H52Cl2FeP2Pd‚
2.3CH2Cl2
C
18H28Cl2FeP2Pd
2CH2Cl2
0.25CH2Cl2
T, K
120
153
120
120
cryst syst, space group
a, Å
b, Å
c, Å
monoclinic, P21/c
19.965(3)
10.402(1)
18.939(3)
orthorhombic, Fdd2
25.320(5)
45.294(9)
14.530(3)
monoclinic, P21/n
12.283(2)
24.199(5)
16.735(3)
monoclinic, P21/n
10.4630(6)
16.7987(9)
11.5739(7)
R, deg
â, deg
γ, deg
V, Å3; Z
Mr
111.534(3)
98.051(5)
94.6840(10)
3658.8(8); 4
1035.86
45.13
2008
1.88
16663(6); 16
872.99
10.52
7080
1.392
4925.3(18); 4
1095.30
11.16
2242
1.477
2027.5(2); 4
539.49
20.22
1088
1.767
µ, cm-1
F(000)
d
calcd, g cm-3
2θmax, deg
no. of rflns measd (Rint
no. of indep rflns
55
54
4651
4651
52
60
)
24 780 (0.0384)
8763
23 470 (0.0888)
9581
13 343 (0.0267)
5784
no. of rflns with I > 2σ(I)
no. of params
7119
415
3330
449
4545
555
4495
217
R1
wR2
0.0406
0.0859
1.084
0.0439
0.0833
0.911
0.0704
0.1425
1.09
0.0451
0.0881
1.081
GOF
max/min peak, e Å-3
1.81/-1.726
0.80/-0.89
1.101/-0.896
1.75/-0.66
morpholine (for the catalyst with the ligand 6): 121 mg (99%).
C6H5), 7.26 (m, 1H, C6H5), 7.05 (m, 2H, C6H4), 6.53 (m, 2H, C6H4),
4.29 (s, 2H, CH2), 3.94 (s, 1H, NH), 2.26 (s, 3H, CH3).
N-(4-Methylphenyl)-N-ethylaniline40 was obtained from N-ethyl-
1
Mp: 42-43 °C (lit.35 mp 43-44 °C). H NMR (CDCl3): δ 7.07
(m, 2H, C6H4), 6.81 (m, 2H, C6H4), 3.84 (m, 4H, CH2), 3.08 (m,
4H, CH2), 2.26 (s, 3H, CH3).
1
aniline and 4-bromotoluene in 96% yield. H NMR (CDCl3): δ
Catalytic Amination of 4-Bromobiphenyl with Morpholine.
4-Bromobiphenyl (100 mg 0.429 mmol), morpholine (45 mg, 0.515
mmol), sodium tert-butoxide (49 mg, 0.515 mmol), and 1 mol %
of palladium catalyst were stirred in dioxane (2 mL) under reflux
for 10 min. The yield of the amination product was determined by
LC.
7.14 (m, 2H, C6H5), 7.05 (m, 2H, C6H4), 6.93 (m, 2H, C6H5), 6.83
(m, 2H, C6H4), 6.78 (m, 1H, C6H4), 3.69 (k, 2H, CH2, J ) 7.2
Hz), 2.26 (s, 3H, CH3), 1.16 (t, 3H, CH3, J ) 7.2 Hz).
N,N-Diphenyl-4-methylaniline41 was obtained from N,N-diphen-
1
ylamine and 4-bromotoluene in 99% yield. H NMR (CDCl3): δ
7.16 (m, 6H, C6H4, C6H5), 6.93 (m, 8H, C6H4, C6H5), 2.26 (s, 3H,
CH3).
Catalytic Amination of 4-Chlorotoluene with Morpholine. The
reaction was carried out according to the general procedure 1 using
the catalyst with ligand 6. The reaction mixture was refluxed for
20 h. N-(4-Methylphenyl)morpholine was obtained in 12% yield
(12 mg) from 86.5 mg (0.684 mmol) of 4-chlorotoluene.
Amination of 1-Chloro-4-(trifluoromethyl)benzene with Mor-
pholine. The reaction was carried out according to the general
procedure 1 using the catalyst with ligand 6. The reaction mixture
was refluxed for 20 h. N-(4-(Trifluoromethyl)phenyl)morpholine
was obtained in 50% yield (79 mg) from 123.5 mg (0.684 mmol)
of 1-chloro-4-(trifluoromethyl)benzene. Mp: 69 °C. (lit.36 mp 69-
Cross-Coupling of 4-Bromotoluene with 4-(Methoxyphenyl)-
boronic Acid. 4-Bromotoluene (50 mg 0.292 mmol), 4-(methoxy-
phenyl)boronic acid (59 mg, 0.385 mmol), potassium carbonate (121
mg, 0.877 mmol), and 1 mol % of palladium catalyst were stirred
in a mixture of dioxane (1.5 mL) and water (0.5 mL) under reflux
for 10 min. The reaction mixture was treated with water and twice
extracted with CH2Cl2. The organic layer was then dried over Na2-
SO4 and concentrated in vacuo. The product was purified by flash
chromatography on silica gel, with a hexane/benzene (6:1:1) mixture
as eluent. Yield of 4-methoxy-4-methylbiphenyl (for the complex
16): 52 mg (99%). Mp: 127-128 °C (lit.42 mp 127-128 °C). 1H
NMR (CDCl3): δ 7.48 (m, 2H, C6H4), 7.42 (m, 2H, C6H4), 7.20
(m, 2H, C6H4), 6.94 (m, 2H, C6H4), 3.81 (s, 3H, OCH3), 2.36 (s,
3H, CH3).
X-ray Structure Determination. X-ray diffraction experiments
for 13, 16, and 18 were carried out with a Bruker SMART 1000
CCD area detector, using graphite-monochromated Mo KR radiation
(λ ) 0.710 73 Å, ω scans with a 0.3° step in ω and 10 s per frame
exposure) at 110 K. The data collection for 15 was performed on
a Syntex P21 diffractometer using graphite-monochromated Mo KR
radiation (λ ) 0.710 73 Å, θ/2θ scans) at 153 K. Reflection
intensities were integrated using SAINT software43 and the semiem-
pirical method SADABS.44 The structures were solved by direct
methods and refined by full-matrix least squares against F2 in an
anisotropic approximation for non-hydrogen atoms. All hydrogen
atoms were placed in geometrically calculated positions and
included in final refinements using the “riding” model with the
Uiso(H) parameters equal to 1.2[Ueq(Ci)] or 1.5[Ueq(Cii)], where
U(Ci) and U(Cii) are respectively the equivalent thermal parameters
1
70 °C). H NMR (CDCl3): δ 7.05 (m, 2H, C6H4), 6.79 (m, 2H,
C6H4), 3.81 (m, 4H, CH2), 3.06 (m, 4H, CH2).
Amination of 4-Bromotoluene by Various Amines. The
reaction was carried out according to the general procedure 1, using
4-bromotoluene (117 mg 0.684 mmol), amine (0.855 mmol), sodium
tert-butoxide (76 mg 0.855 mmol) and PdCl2*6 (6 mg, 6.84 mmol).
1
Yields of the products were determined by H NMR.
N-Dodecyl-4-methylaniline37 was obtained from n-dodecylamine
1
and 4-bromotoluene in 85% yield. H NMR (CDCl3): δ 7.01 (m,
2H, C6H4), 6.52 (m, 2H, C6H4), 4.61 (s, 1H, NH), 3.10 (t, 2H, CH2),
2.28 (s, 3H, CH3), 1.62 (m, 2H, CH2), 1.35 (m, 18H), 0.92 (m, 3H,
CH3).
N-2-(Methoxyphenyl)-4-methylaniline38 was obtained from 2-meth-
1
oxyaniline and 4-bromotoluene in 80% yield. H NMR (CDCl3):
δ 7.04 (m, 2H, C6H4), 6.74 (m, 2H, C6H4), 6.80 (m, 4H, C6H4),
4,23 (s, 1H, NH), 3.77 (s, 3H, OCH3), 2.26 (s, 3H, CH3).
N-Benzyl-4-methylaniline39 was obtained from benzylamine and
1
4-bromotoluene in 87% yield. H NMR (CDCl3): δ 7.33 (m, 4H,
(35) Tsuji, Y.; Huk, K.-T.; Ohsugi, Y.; Watanabe, Y. J. Org. Chem. 1985,
50, 1365.
(36) Kamikawa, K.; Sugimoto, S.; Uemura, M. J. Org. Chem. 1998, 63,
8407.
(37) Kao, G. N.; Tilak, B. D.; Venkataraman, K. J. Sci. Ind. Res. 1955,
14, 624.
(38) Sundberg, R. J.; Sloan, K. B. J. Org. Chem. 1973, 38, 2052.
(39) Mailhe, M. A. C. R. Hebd. Seances Acad. Sci. 1921, 172, 280.
(40) Stroh, H. Chem. Ber. 1958, 91, 2645.
(41) Marsden, R. J. B. J. Chem. Soc. 1937, 627.
(42) Riguet, E.; Alami, M.; Cahiez, C. Tetrahedron Lett. 1997, 38, 4397.
(43) SMART version 5.051 and SAINT version 5.00, Area Detector
Control and Integration Software; Bruker AXS Inc., Madison, WI, 1998.
(44) Sheldrick, G. M., SADABS; Bruker AXS Inc., Madison, WI, 1997.

2760 Organometallics, Vol. 25, No. 11, 2006
GuseV et al.
of the methyne and methylene carbon atoms to which corresponding
H atoms are bonded. Crystal data and structure refinement
parameters for 13, 15, 16, and 18 are given in Table 6. All
calculations were performed on an IBM PC/AT computer using
SHELXTL software.45
(Grant 03-03-32471), and to the Science Support Foundation
of the Russian Federation for financial support.
Supporting Information Available: CIF files giving crystal-
lographic data for compounds 13, 15, 16, and 18. This material
is available free of charge via the Internet at http://pubs.acs.
org.
Acknowledgment. Thanks are due to a CNR-RAS bilateral
agreement, to the Russian Foundation for Basic Research
(45) Sheldrick, G. M. SHELXTL-97, version 5.10; Bruker AXS Inc.,
Madison, WI, 1997.
OM050869W