Palladium chemistry of 2-ferrocenyl-1,10-phenanthroline ligand

Article abstract of DOI:10.1021/om060703a

The synthesis of the 2-ferrocenyl-1,10-phenanthroline ligand 1 has been improved, and its reactivity toward palladium is described. This study allows evidencing that 1 can coordinate to the metal center in an N-N bidentate fashion or undergo ortho metalation, thus acting as a terdentate N-N-C pincer ligand. Examples of the former coordination mode include complexes [Pd(Cl)(Me)(1)] (2) and [Pd(Me)(NCMe)-(1)][PF₆] (3), whereas cyclometalation is observed in [Pd(1)(O₂CCF₃)] (5), [Pd(1)(MeCN)][PF₆] (6), and [Pd(1)(PPh₃)][O₂CCF₃] (7). These cyclometalated adducts are chiral, racemic compounds. X-ray crystal structures of compounds 5, 6, and 7 have been determined, confirming the presence of a five-membered palladacycle and evidencing that in the solid state packing occurs through weak π-π interactions between the phenanthroline rings of the ligands. The reactivity of the racemic mixture of 5 with the enantiopure phosphine (R)-Ph-BINEPINE (8) affords a kinetic dynamic resolution leading, after two recrystallizations, to the isolation of only one of the two possible diastereoisomers.

Full text of DOI:10.1021/om060703a

810
Organometallics 2007, 26, 810-818
Palladium Chemistry of 2-Ferrocenyl-1,10-phenanthroline Ligand
Je´roˆme Durand,*,†,# Serafino Gladiali,‡ Giulia Erre,‡ Ennio Zangrando,† and Barbara Milani†
Dipartimento di Scienze Chimiche, UniVersita` degli Studi di Trieste, Via Licio Giorgieri 1, 34127 Trieste,
Italy, and Dipartimento di Chimica, UniVersita` di Sassari, Via Vienna 2, 07100 Sassari, Italy
ReceiVed August 3, 2006
The synthesis of the 2-ferrocenyl-1,10-phenanthroline ligand 1 has been improved, and its reactivity
toward palladium is described. This study allows evidencing that 1 can coordinate to the metal center in
an N-N bidentate fashion or undergo ortho metalation, thus acting as a terdentate N-N-C pincer ligand.
Examples of the former coordination mode include complexes [Pd(Cl)(Me)(1)] (2) and [Pd(Me)(NCMe)-
(1)][PF6] (3), whereas cyclometalation is observed in [Pd(1)(O2CCF3)] (5), [Pd(1)(MeCN)][PF6] (6), and
[Pd(1)(PPh3)][O2CCF3] (7). These cyclometalated adducts are chiral, racemic compounds. X-ray crystal
structures of compounds 5, 6, and 7 have been determined, confirming the presence of a five-membered
palladacycle and evidencing that in the solid state packing occurs through weak π-π interactions between
the phenanthroline rings of the ligands. The reactivity of the racemic mixture of 5 with the enantiopure
phosphine (R)-Ph-BINEPINE (8) affords a kinetic dynamic resolution leading, after two recrystallizations,
to the isolation of only one of the two possible diastereoisomers.
In this paper we report on the synthesis and characterization
of different palladium complexes containing the 2-ferrocenyl-
1,10-phenanthroline (1) moiety, a ligand that can bind the metal
either in N-N bidentate or in N-N-C tridentate fashion. In
the latter case, the intramolecular metalation of the ipso
cyclopentadienyl ring generates a chiral N-N-C pincer pal-
ladacycle featuring a stereogenic plane as the unique chiral
element. While optically active pincer palladacycles with
stereogenic carbon atom(s) in the ligand backbone are not rare,
pincer palladacycles with planar chirality are almost unprec-
edented.
Introduction
Palladacycles represent a class of compounds of remarkable
importance that have found a number of applications in the field
of organometallic chemistry. These complexes have been widely
used in catalysis,1 especially for C-C bond formation, as
resolving agents,2 and studied for their luminescence properties,3
their capability of interacting with DNA,4 or as building blocks
for molecular architectures of higher complexity.5 A wide variety
of tridentate ligands have been exploited for the preparation of
palladacycles. Among these, N-C-N pincer ligands have
received particular attention,6 and they are encountered much
more frequently than their N-N-C counterparts.7
Chiral ferrocenyl-based ligands have been extensively used
in homogeneous enantioselective catalysis.8 Nevertheless, pal-
ladacycles arising from the N-supported metalation at the sp2
carbon atom of a cyclopentadienyl ring of a pincer ferrocenyl
ligand are surprisingly few,9 and even less are the derivatives
of this type that have been tested in catalytic reactions.10
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* Corresponding author. E-mail: durand@chimie.ups-tlse.fr.
† Universita` degli Studi di Trieste.
# Current address: Laboratoire He´te´rochimie Fondamentale et Applique´e,
Universite´ Paul Sabatier, UMR CNRS 5069, Baˆtiment 2R1, 118, route de
Narbonne, 31062 Toulouse Cedex 9, France.
‡ Universita` di Sassari.
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10.1021/om060703a CCC: $37.00 © 2007 American Chemical Society
Publication on Web 01/17/2007

Pd Chemistry of 2-Ferrocenyl-1,10-phenanthroline Ligand
Organometallics, Vol. 26, No. 4, 2007 811
the ferrocenyl moiety and thus the latter one to the isomer 2b
Results and Discussion
(eq 2). The NOE experiment also indicates that the two isomers
Synthesis of 2-Ferrocenyl-1,10-phenanthroline, 1. The
preparation of 2-ferrocenyl-1,10-phenanthroline (1) has been
readily accomplished through the Friedlander condensation of
ferrocenyl methyl ketone with 8-amino-7-quinoline carboxyal-
dehyde (eq 1). The reaction is performed in ethanolic KOH and
are in equilibrium. At room temperature, the rate of this
equilibrium is low on the NMR time scale. All the aromatic
protons were attributed with a 2D homonuclear correlation
experiment (COSY). Chemical shifts of all the protons are very
similar to those reported previously for the complex [PdCl2-
(1)].9a In particular, in the dichloro derivative, a value of 9.34
ppm is observed, comparable to that of H9 in 2b (9.27 ppm). In
the case of 2a, the absence of a cis-chloro ligand leads the H9
proton to resonate at 8.87 ppm, in agreement with the fact that
the Pd-Cl significantly shifts to higher frequency the resonance
of the proton cis to it.13 This provides further support to the
attribution of the structure of the two isomers made on the basis
of the NOE experiments.
When 2 is reacted with AgPF6 in the presence of acetonitrile,
the cationic complex 3 is formed (Scheme 1). It is interesting
to note that, unlike the neutral precursor, in this case just one
isomer is obtained even when starting from a mixture of 2a
and 2b. The NOE between the H9 proton of the phenanthroline
and the Pd-Me at 1.15 ppm shows that in this complex the
coordinated acetonitrile sits in cis position to the ferrocenyl
group of the ligand.
is completed in 6 h reflux. This methodology, modeled on a
procedure recently established for the preparation of alkyl-
substituted phenanthrolines,11 affords the desired ligand in 65%
isolated yield and is by far better yielding than the previously
reported preparation of 1 from 2-chlorophenanthroline and
ferrocenyl lithium.12
Palladium Chemistry. Reaction of 1 with [Pd(Cl)(Me)-
(COD)] (COD ) 1,5-cyclooctadiene) leads to the formation of
a dark red product 2. Its 1H NMR spectrum provides evidence
of the presence in solution of the two possible isomers due to
the unsymmetrical nature of the ligand. Two singlets for the
Pd-Me group, one for each of the two isomers, are present at
1.07 (major product) and 0.33 (minor product) ppm in a 3:2
ratio. NOE experiments allow us to assign the former to the
isomer 2a, having the Cl ligand cis to the aromatic ring bearing
(8) (a) Ferrocenes: Homogeneous Catalysis, Organic Synthesis, Material
Science; Togni, A., Hayashi, T., Eds.; VCH: Weinheim, 1995. (b) Colacot,
T. J. Chem. ReV. 2003, 103, 3101. (c) Barbaro, P.; Bianchini, C.;
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Asymmetry 1996, 7, 2527. (d) Bosque, R.; Lo´pez, C.; Sales, J.; Solans, X.;
Silver, J. J. Chem. Soc., Dalton Trans. 1996, 3195. (e) Lo´pez, C.; Bosque,
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1997, 547, 309. (g) Zhao, G.; Xue, F.; Zhang, Z.-Y.; Mak, T. C. W.
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Panyashkina, I. M.; Kazankov, G. M.; Polyakov, V. A.; Kuz’mina, L. G.
J. Organomet. Chem 2000, 601, 51. (l) Lo´pez, C.; Bosque, R.; Solans, X.;
Font-Bardia, M. Polyhedron 2001, 20, 987. (m) Lo´pez, C.; Caubet, A.;
Pe´rez, S.; Solans, X.; Font-Bard´ıa, M. J. Organomet. Chem. 2002, 651,
105. (n) Lo´pez, C.; Pawelczyk, A.; Solans, X.; Font-Bard´ıa, M. Inorg. Chem.
Commun. 2003, 6, 451. (o) Pe´rez, S.; Lo´pez, C.; Caubet, A.; Bosque, R.;
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2005, 127, 2388. (q) Pe´rez, S.; Lo´pez, C.; Caubet, A.; Solans, X.; Font-
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Chem. 2001, 637-639, 793. (b) Kang, J.; Yew, K. H.; Kim, T. H.; Choi,
D. H. Tetrahedron Lett. 2002, 43, 9509. (c) Roca, F. X.; Richards, C. J.
Chem. Commun. 2003, 3002. (d) Iyer, S.; Kulkarni, G. M.; Ramesh, C.
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A. Tetrahedron 2005, 61, 9767. (g) Zhao, X. M.; Hao, X. Q.; Zhang, M.
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691, 1301.
Scheme 1. Reactivity of 2 with AgPF6 or with MeCO2Na
The bidentate coordination displayed by ligand 1 in the
adducts 2 and 3 is identical to that previously observed in the
complex [PdCl2(1)] prepared from ligand 1 and [PdCl2(COD)].
Notably, in this latter reaction, the corresponding 6-ferrocenyl-
2,2′-bipyridine analogue of 1 undergoes direct cyclometalation
at the ipso cyclopentadienyl ring, leading to the formation of
[PdCl(6-ferrocenyl-2,2′-bipyridine)], where the 6-ferrocenyl-
2,2′-bipyridine acts as a monoanionic tridentate ligand.9a The
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R. P. J. Org. Chem. 2001, 66, 400.
(12) Butler, I. R.; Roustan, J.-L. Can. J. Chem. 1990, 68, 2212.
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Leeuwen, P. W. N. M.; Vrieze, K. Inorg. Chem. 1993, 32, 5769.

812 Organometallics, Vol. 26, No. 4, 2007
Scheme 2. Reactivity of 1 with [Pd(OAc)2] and Further Reactions
Durand et al.
preparation of the analogous phenanthroline complex [PdCl-
(1)] could be achieved by reaction of 1 with K2[PdCl4].9j
ized both in the solid state (by X-ray diffraction; see below
and Figure 1) and in solution by 1H NMR spectroscopy. As in
We have observed that an analogous cyclopalladated complex
4, where deprotonated 1 acts as an anionic tridentate N-N-C
pincer ligand, is obtained by reacting the adduct 2 with sodium
acetate. Apparently, the presence of a base, even a weak one,
is necessary for 2 to undergo the intramolecular cyclometalation
to 4 (Scheme 1) as reported in some cases of cyclopalladation
processes.1e,7a,9b-d,f-i,m-o,10f Note that the conversion of 2 is
complete and that no traces of unreacted 2b, which does not
possess the appropriate geometry for the substitution to occur,
are observed at the end of the reaction. This behavior is in
agreement with the equilibration between 2a and 2b.
Direct cyclopalladation of 1 is also observed on the attempted
preparation of the bis-trifluoroacetate adduct [Pd(O2CCF3)2(1)]
from [Pd(OAc)2]. This reaction was performed by adding ligand
1 to a methanolic solution of [Pd(OAc)2] according to a
procedure devised by us for the synthesis of similar N-N
chelate complexes.14 Addition of trifluoroacetic acid to the red
solution, probably containing the adduct [Pd(OAc)2(1)], resulted
in the separation of a dark blue solid, 5 (Scheme 2), character-
Figure 1. Molecular structure of complex 5 (ORTEP drawing with
40% probability ellipsoids).
the case of 4, the 1H NMR spectrum of the isolated solid
evidences the presence of a metalated ferrocene cyclopentadienyl

Pd Chemistry of 2-Ferrocenyl-1,10-phenanthroline Ligand
Organometallics, Vol. 26, No. 4, 2007 813
Figure 2. Molecular structure of the cation of 6 (ORTEP drawing
with 40% probability ellipsoids).
Figure 3. Molecular structure of the cation of 7 (ORTEP drawing
with 30% probability ellipsoids). Only the ipso C atoms of the
phenyl rings are labeled for clarity.
ring. Three different signals, each one integrating for one proton,
are observed for the cyclopentadienyl ring bonded to palladium.
Coupling constants together with two-dimensional homonuclear
correlation experiments (COSY) confirm that the cyclometal-
lation occurs exclusively at the ipso carbon atom of the
cyclopentadienyl ring, generating a five-membered palladacycle,
according to Cope’s rule.
reaction points out that, unlike the case of triphenylphosphine,
with this ligand the reaction is almost instantaneous since no
signal corresponding to the free phosphine 8 at 6.5 ppm is
observed in the spectrum recorded immediately after the
dissolution of the reagents. Since in the case of 9 the generation
of the stereogenic plane inherent with the cyclometalation
implies the removal of one pair of diastereotopic protons, two
diastereomers are expected from this reaction. Accordingly, the
two resonances in 2:1 ratio observed in 31P{1H} NMR at 42.0
and 42.5 ppm are attributed to the two diastereoisomers (R,SP)
and (R,RP) that can result from the reaction of racemic 5 with
the enantiopure (R)-Ph-BINEPINE, 8. The 31P{1H} chemical
shifts of the two isomers of 9 are similar to those observed in
other palladium complexes with this ligand and confirm the
phosphine binding to palladium.15 The coordination-induced
downfield shift is also comparable to that observed in the case
of the reaction with PPh3. In the case of 9, again, the
cyclometalated structure is maintained, as can be evidenced in
the 1H NMR spectrum by the resonances of the cyclopentadienyl
ring bound to both the phenanthroline backbone and the
palladium center. The signals of some protons of the cyclopen-
tadiene rings are a probe of the presence of the two diastereo-
isomers. In particular, in the major diastereoisomer both the
singlet of the protons of the cyclopentadienyl ring (3.69 ppm)
not bound to palladium and the broad signal of HR (4.26 ppm)
are remarkably shifted to lower frequency than the same signals
both in 5 and in the minor diastereoisomer (4.28 ppm for the
5H of Cp and 4.70 ppm for HR in 5; 4.22 ppm for the 5H of Cp
and 4.59 ppm for HR in the minor diastereoisomer), thus
suggesting that in the major diastereoisomer the cyclopentadi-
enyl moiety is more affected by the presence of 8 than in the
minor isomer.
Complex 5 was used as the starting material for the synthesis
of other cyclometalated complexes (Scheme 2). Its reaction with
NaPF6 in the presence of acetonitrile leads to the formation of
1
the cationic complex 6. In its H NMR spectrum a singlet at
2.58 ppm, characteristic of the coordinated acetonitrile, is
observed. The spectrum presents three very broad signals for
the cyclometalated cyclopentadienyl ring when recorded in
acetone-d6, whereas when CD2Cl2 is the solvent, they are not
observed at room temperature and start to be visible at -70
°C.
Reaction of 5 with 1 equiv of PPh3 leads slowly to the
formation of the cationic complex 7, the reaction being
completed after one night, at room temperature. Coordination
of the phosphine is confirmed by the singlet at 35.3 ppm in the
31P{1H} NMR spectrum, while the H NMR evidences the
1
retention of the cyclometalated structure. Unlike in the case of
6, the signals of the protons in the NMR spectrum of 7 are
well resolved, allowing the observation of the multiplicity for
the three resonances of the palladated cyclopentadienyl ring.
In the aromatic region, apart from the expected signals for the
phenyl groups of the phosphine, the seven protons of the
phenanthroline backbone are observed. Remarkable in this case
is the high upfield shift of the signal of H9 (6.85 ppm), with
respect to the same frequency in both the free ligand 1 (9.21
ppm) and in 5 (8.80 ppm). A similar shift is observed for the
signal of one of the protons of the cyclopentadienyl ring bound
to palladium (3.55 ppm) and for the singlet due to the five
protons of the Cp ring (3.81 ppm). This is attributed to the
shielding effect of the phenyl rings of the coordinated phosphine.
The crystal structures of 6 and 7 were resolved by X-ray
diffraction (see below and Figures 2, 3) on single crystals. This
structural analysis provides further evidence of the terdentate
coordination mode of the 2-ferrocenyl-1,10-phenanthroline
ligand 1 in these complexes.
Addition of diethyl ether to a chloroform solution of this
mixture afforded a crop of crystals where the isomer ratio
improved up to 5:1. One further crystallization gave a sample
of the pure diastereoisomer featuring 31P{1H} NMR at 42.0 ppm.
The optical activity of a chloroform solution of the solid isolated
after the second crystallization process has been measured (see
Experimental Section), confirming that the complex is optically
active. 31P{1H} NMR inspection of the filtrate from these
crystallizations points out that the diastereomeric ratio in solution
is 2:1 and that this value is constant with time.
The reaction of 5 with 1 equiv of the enantiopure (R)-Ph-
BINEPINE, the axially chiral monodentate phosphine 8,15 leads
to complex 9 (Scheme 2). 31P{1H} NMR monitoring of the
(14) Milani, B.; Alessio, E.; Mestroni, G.; Sommazzi, A.; Garbassi, F.;
Zangrando, E.; Bresciani-Pahor, N.; Randaccio, L. J. Chem. Soc., Dalton.
Trans. 1994, 1903.
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Tetrahedron: Asymmetry 1994, 5, 511.

814 Organometallics, Vol. 26, No. 4, 2007
Durand et al.
Table 1. Selected Bond Lengths (Å) and Angles (deg) and Geometrical Parameters of the Ferrocenyl Moiety for Compounds 5,
6, and 7
5 (X ) O(1))
2.173(3)
1.965(3)
1.980(4)
2.043(3)
2.024(4)-2.064(4)
1.660, 1.652
6 (X ) N(3))
2.173(7)
1.984(7)
1.986(9)
1.984(9)
2.032(9)-2.058(10)
1.666, 1.640
7 (X ) P(1))
2.197(8)
2.014(8)
1.979(10)
2.249(3)
1.990(12)-2.095(17)
1.672, 1.635
Pd-N(1)
Pd-N(2)
Pd-C(15)
Pd-X
Fe-C(Cp)
Fe-Cp centroid
N(1)-Pd-N(2)
N(1)-Pd-C(15)
N(2)-Pd-C(15)
N(1)-Pd-X
79.29(13)
160.05(14)
80.77(14)
97.71(12)
175.72(11)
102.24(15)
141.7(3)
80.2(3)
160.6(3)
80.4(3)
100.9(3)
178.9(3)
98.5(3)
141.9(8)
174.7(8)
78.5(3)
158.0(4)
79.6(4)
107.9(2)
173.5(3)
94.0(3)
142.2(8)
N(2)-Pd-X
C(15)-Pd-X
C(19)-C(15)-Pd
C(13)-X-Pd
129.6(3)
Cp1/Cp2
twist angle Cp1/Cp2
phen/C(15-19) ring
3.2(2)
5.2
3.8(2)
1.6(4)
10.7
0.9(5)
4.61(8)
8.8
7.93(5)
These results indicate not only that the axially chiral (R)-Ph-
BINEPINE (8) can be successfully exploited as a resolving agent
for the chiral palladacycle reported in this work but also that
the cationic complex 9 is configurationally labile and that the
two diastereoisomers, in solution, undergo an interconversion
process until they reach the equilibrium concentration 2:1, at
room temperature. For this equilibration to occur, opening of
the palladacycle ring followed by rotation around the C-C bond
connecting the phenanthroline to the cyclopentadienyl ring is
required.
diphosphine. This observation, together with the quantitative
consumption of the reagents in a 2:1 ratio, allows us to rule out
the formation of mononuclear species with a chelating diphos-
phine around the palladium center. Such a behavior of bidentate
phosphines toward cyclometalated complexes, which occurs
through opening of a chelate ring via dissociation of one nitrogen
atom of the ligand, has been reported in some cases.7h,8i
Structure Description. Single crystals suitable for X-ray
analysis were obtained upon crystallization from dichloromethane/
diethyl ether for complexes 5 and 7, whereas they were directly
isolated from the crude reaction mixture for 6.
The molecular structures of complexes 5, 6, and 7 with the
atom-numbering scheme are shown in Figures 1, 2, and 3,
respectively. In all the structures the palladium atom displays a
distorted square planar geometry, being chelated by the terden-
tate ferrocenyl ligand and having the monocoordinated trifluo-
roacetate-O (5), acetonitrile-N (6), or phosphine-P (7) as fourth
ligand. A selection of bond distances, angles, and geometrical
parameters is reported in Table 1.
These data indicate comparable values of the bond distances
and angles in the coordination sphere, with the exception of
the values relative to the N(2)-Pd-X fragment. In fact the Pd-
N(2) bond length trans to the trifluoroacetate appears slightly
shorter, 1.965(3) Å, with respect to the values measured in the
monocationic 6 and 7 derivatives (1.984(7) and 2.014(8) Å,
respectively). Moreover, a comparison of the N-Pd-X and
C-Pd-X bond angles reveals slightly different values within
a few degrees in 5, 6, and 7. As expected the Pd-N(1) bond
distance is significantly longer in comparison with the Pd-
N(2), the former phen nitrogen being located trans to the
ferrocene C atom. In all the complexes the donors of the
coordination sphere are coplanar with the palladium atom. Both
the five-membered rings formed by the terdentate ferrocenyl
ligand have coordination bond angles N(1)-Pd-N(2) and
N(2)-Pd-C(15) close to 79-80° in all the complexes. In the
palladate compounds, the formation of a σ (Pd-Csp2 ferrocene)
bond is expected to modify the ring current in the ferrocenyl
moiety and the redox behavior of the iron center. However
geometrical data in the solid state indicate that the terdentate
N-N-C ligands are rigid, the coordination geometry being
rather unaffected by the electronic and steric properties of the
fourth ligand at Pd. This is also indicated by comparable Pd-
Fe distances, of 3.505 (for 5), 3.550 (6), and 3.591 Å (7), which
exclude any interaction between the metals. To our knowledge,
only two examples of Pd-Cl complexes with a metalated
ferrocenyl-phen9j and ferrocenyl-bipy9a have been reported. The
The configuration of these isomers, however, could not be
cleared and all attempts to grow crystals suitable for X-ray
diffraction were unsuccessful.
When 2 equiv of 5 are reacted with a diphosphine such as
1,2-bis(diphenylphosphino)ethane (dppe) or 1,3-bis(diphe-
nylphosphino)propane (dppp), a quantitative immediate reaction
takes place, affording the hetero-tetrametallic complexes 10 and
11, respectively (Scheme 2). 31P{1H} NMR spectra display, in
both cases, two very close resonances due to the formation of
diastereoisomers, as expected from the reaction of the diphos-
phine with the racemic mixture of 5. Their chemical shifts are
indicative of the coordination of the phosphorus donor atoms
1
to palladium. H NMR spectra show two sets of three rather
broad resonances for the protons of the cyclometalated cyclo-
pentadienyl rings, evidencing the retention of the cyclometalated
structure. However, at room temperature the protons of the free
Cp rings give only one large signal, which is split into two
distinct signals when the measurement is performed at temper-
atures below -20 °C for 11 and around 0 °C for 10. Lowering
the temperature did not allow observing a better resolution of
the spectra, all signals still being broad at -60 °C. The signals
for the H9 protons of the phenanthroline backbones are, as
observed in 7, upfield shifted, though this effect is less
pronounced than in the case of the complex containing the
triphenylphosphine (e.g., 7.21 ppm in 10 vs 6.85 ppm in 7). In
the aromatic region the presence of the signals of the phenyl
rings of the diphosphine and the presence of a large number of
signals for the phenanthroline protons render difficult the
complete assignment for all of them. As a general comment,
signals are broader in the case of 11 than for 10. NMR
measurements were performed at higher temperature, in dmso-
d6. Signals become better resolved at 100 °C. In the 31P{1H}
NMR spectra, no significant change was observed in the studied
1
range of temperature. Integration of the H NMR spectrum of
11 evidences the presence of two palladacycle units for one
diphosphine, supporting a bridging coordination mode of the

Pd Chemistry of 2-Ferrocenyl-1,10-phenanthroline Ligand
Organometallics, Vol. 26, No. 4, 2007 815
ligands give rise to π-π interactions. In the neutral complex 5
the centroids of the five-membered rings Pd/N1/C5/C6/N2 are
separated by 3.42 Å, so that each nitrogen N(2) lies over the
Pd ion of the symmetry-related complex at 3.560 Å, ap-
proximately located at the apical position of the square
coordination plane (Figure 4). The pairing of structural complex
units was also found in the isomorphous Pt and Pd compounds
containing a terdentate [C(sp2, ferrocene)-N-S] ligand.8o In
complex 7 the face-to-face alignment leads the two phen
fragments to be at a mean distance of 3.43 Å between the
-
symmetry-related py ring centroids (Figure 5). The CF3CO2
anions and CH2Cl2 solvent molecules do not evidence any
unusual close contact with the metal complexes.
On the other hand, compound 6 shows a different crystal
packing with Cp rings that contribute, beside the phen ligands,
to π-π intermolecular interactions. The molecules are pillared
in columns, running parallel to the crystallographic axis a, as
illustrated in Figure 5c. This arrangement of molecules re-
sembles the packing found in the neutral [PdCl(1)] species,9j
and both can be favored by the presence of the less bulky
monocoordinated MeCN and Cl9j ligand in comparison to the
Figure 4. Packing arrangement of complex 5 viewed down axis
a.
-
CF3CO2 (for 5) and PPh3 one (for 7).
Some authors have postulated that the π-stacking of the
terdentate ligand in Pd and Pt complexes and the M-M
separation are relevant for photoluminiscent properties.3b,c,16 The
Pd-Pd intradimer distances in 5 and 7 are 4.323(1) and 6.872-
(2) Å, respectively, while the shortest Pd-Pd separation in 6 is
4.527(2) Å; all these values are larger than the sum of the van
der Waals metal ion radii, thus excluding any metal-metal
interactions.8o
Catalytic Tests. Complex 3 was tested in the CO/styrene
copolymerization in 2,2,2-trifluoroethanol, in the presence of
1,4-benzoquinone ([BQ]/[Pd] ) 5) at 30 °C under an atmo-
spheric pressure of carbon monoxide. After 8 h, only traces of
copolymers were obtained. The same complex has also been
tested in the benchmark Heck reaction of iodobenzene with
methyl acrylate. The reaction has been run for 14 h at 110 °C
at a substrate-to-Pd ratio of 103 using DMF as solvent and
triethylamine as base. The reaction affords methyl trans-
cinnamate with a 98% conversion. No apparent precipitation
of palladium was noticed during the reaction.
geometry of the terdentate ligand in these chlorine derivatives
agrees well with those presented here. The ferrocene moieties
are similar in all complexes, and the greater variations in the
geometry are observed in complex 7, mainly ascribed to the
less accurate geometrical data but also to the presence of the
bulky phosphine ligand. In all complexes the cyclopentadienyl
rings are parallel, the largest interplanar angle being 4.61(8)°
observed in the phosphine complex, and they deviate by 5.2°,
10.7°, and 8.8° in 5, 6, and 7, respectively, from the ideal
eclipsed conformation. The Fe-C bond lengths fall in a range
from 1.990(12) to 2.095(17) Å, with the iron atom slightly
displaced toward the metalated ring (ca. 1.67 vs 1.64 Å). The
C-C bond length associated to the chelating ring (C(15)-C(16)
of ca. 1.45 Å) appears the longest inside the cyclopentadienyl
rings. Finally, the phenanthroline mean plane is essentially
coplanar with the substituted cyclopentadienyl ring in 5 and 6,
while the calculated dihedral angle in 7 is 7.93(5)°.
In the crystal these systems are efficiently packed through
the establishment of weak interactions between parallel planar
phenanthroline ligands. In 5 and 7 the complexes are associated
in pairs, forming head-to-tail dimers related by a crystal-
lographic symmetry center in such a way that the facing phen
Further investigations on the catalytic behavior of the
palladacycles described in this work are currently in progress
in our laboratories.
Figure 5. View of the head-to-tail dimer of 5 (a) and 7 (b) related by an inversion center. (c) Crystal packing of complex 6 pillared along
axis a.

816 Organometallics, Vol. 26, No. 4, 2007
Durand et al.
1H NMR (400 MHz, CDCl3, 25 °C): δ 4.08 (s, 5H, Cp), 4.49
Conclusion
3
3
(d, JH,H ) 1.8 Hz, 1H, Hâ of C5H4), 4.50 (d, JH,H ) 2.1 Hz, 1H,
3
Hâ of C5H4), 5.23 (d, JH,H ) 2.1 Hz, 1H, HR of C5H4), 5.24 (d,
In the course of this investigation we have devised practical
procedures for the preparation of racemic Pd complexes
featuring as a unique chiral element a stereogenic plane arising
from the N-N-C terdentate coordination of 2-ferrocenyl-1,-
10-phenanthroline ligand 1. Both neutral and cationic complexes
of this kind are accessible by a two-step procedure involving
the intermediate isolation of the N-N chelate adducts followed
by reaction with a suitable base. Alternatively, the same
compounds can be straightforwardly obtained in a single-pot
reaction when using Pd derivatives with poorly coordinative
anions as precursors. A suitable procedure for the resolution of
the enantiomers of the cationic cyclopalladated fragment has
been established by using the axially chiral monodentate
phosphine (R)-Ph-BINEPINE (8) as chiral resolving agent. Some
traits of the catalytic activity and of the supramolecular structure
in the solid state of these Pd complexes have been pointed out.
Further work aimed at clearing the optical properties and the
utility of these derivatives in asymmetric catalysis is in progress.
3
3JH,H ) 1.8 Hz, 1H, HR of C5H4), 7.60 (dd, JH,H ) 8.1 Hz and
3JH,H ) 4.5 Hz, 1H, H8), 7.74-7.78 (m, 2H, H5 and H6), 7.83 (d,
3JH,H ) 8.4 Hz, 1H, H3 or H4), 8.14 (d, 3JH,H ) 8.4 Hz, 1H, H3 or
3
4
H4), 8.23 (dd, JH,H ) 8.1 Hz and JH,H ) 1.8 Hz, 1H, H7), 9.21
(dd, JH,H ) 4.5 Hz and JH,H ) 1.8 Hz, 1H, H9). 13C NMR
(CDCl3): δ 160.1 (C2), 150.1 (C9), 145.9, 145.8, 136.0 (C7), 135.5
(C4), 129.1, 126.8, 126.6 (C5 or C6), 125.2 (C5 or C6), 122.6 (C8),
121.3 (C3), 84.2 (C ipso of C5H4), 70.3 (CR of C5H4), 69.7 (C of
Cp), 68.6 ppm (Câ of C5H4). MS: m/e 364.8 (M+), 342.0, 317.0,
301.0, 279.1, 263.1.
3
4
[Pd(Cl)(Me)(1)], 2. To a stirred solution of [Pd(Cl)(Me)(COD)]
(0.070 g, 0.26 mmol) in 10 mL of CH2Cl2, under argon, was added
1 as a solid (0.107 g, 0.294 mmol). After 1 h, addition of diethyl
ether to the dark red solution caused the precipitation of a red solid,
which was filtered, washed with diethyl ether, and dried under
vacuum. Yield: 80%.
1
2a: H NMR (400 MHz, CD2Cl2, 25 °C): δ 1.07 (s, 3H, Pd-
Me), 3.94 (s, 5H, Cp), 4.58 (t, 3JH,H ) 1.95 Hz, 2H, C5H4), 5.36 (t,
3JH,H ) 1.95 Hz, 2H, C5H4), 7.7-7.8 (m, 1H, H8), 7.86-7.92 (m,
Experimental Section
3
2H, H5 and H6), 8.08 (d, JH,H ) 8.79 Hz, 1H, H3 or H4), 8.26 (d,
3
3JH,H ) 8.79 Hz, 1H, H3 or H4), 8.49 (dd, JH,H ) 7.81 Hz and
The dichloromethane used for the synthesis of complexes was
purified through distillation over CaCl2 and stored under an inert
atmosphere. Other solvents (Carlo Erba, Fluka) were used as
received. [Pd(OAc)2] was a gift from Engelhard Italia. Carbon
monoxide (CP grade, 99.9%) was supplied by SIAD.
4JH,H ) 1.47 Hz, 1H, H7), 8.87 (1H, dd, 3JH,H ) 5.37 Hz, H9) ppm.
1
2b: H NMR (400 MHz, CD2Cl2, 25 °C): δ 0.33 (s, 3H, Pd-
Me), 4.01 (s, 5H, Cp), 4.61 (t, 3JH,H ) 1.95 Hz, 2H, C5H4), 5.40 (t,
3JH,H ) 1.95 Hz, 2H, C5H4), 7.7-7.8 (m, 1H, H8), 7.86-7.92 (m,
3
2H, H5 and H6), 8.07 (d, JH,H ) 8.30 Hz, 1H, H3 or H4), 8.28 (d,
1H NMR spectra were recorded at 400 MHz, on a JEOL EX
400 spectrometer; the resonances were referenced to the solvent
peak versus TMS (CDCl3 at 7.26 δ, CD2Cl2 at 5.33 δ, CD3CN at
1.94 δ, dmso-d6 at 2.50 δ, acetone-d6 at 2.05 δ). Attribution of the
resonances for all the complexes was made on the basis of two-
dimensional homonuclear correlation spectra (COSY) obtained with
the automatic program of the instrument. The NOE experiments
were run with a 1H pulse of 90° of 12.3 µs. 31P{1H} NMR spectra
were recorded on a JEOL EX 400 at 161.8 MHz and on a JEOL
270 at 109.25 Hz and referenced to an H3PO4 external standard.
Elemental analyses (C, H, N), performed at Dipartimento di Scienze
Chimiche (Universita` di Trieste), were in perfect agreement with
the proposed stoichiometry. PPh3, 1,2-bis(diphenylphosphino)ethane
(dppe), and 1,3-bis(diphenylphosphino)propane (dppp) are com-
mercial and were used as received.
3
3JH,H ) 8.30 Hz, 1H, H3 or H4), 8.44 (dd, JH,H ) 8.30 Hz and
3
4
4JH,H ) 1.47 Hz, 1H, H7), 9.27 (dd, JH,H ) 4.88 Hz and JH,H
)
1.46 Hz, 1H, H9) ppm. Anal. Calcd for C23H19ClFeN2Pd: C, 53.01;
H, 3.67; N, 5.38. Found: C, 53.3; H, 4.09; N, 5.42.
[Pd(Me)(NCMe)(1)][PF6], 3. A solution of AgPF6 (0.023 g, 0.09
mmol) in 1 mL of anhydrous MeCN was added to a stirred solution
of 2 (0.04 g, 0.08 mmol) in 10 mL of CH2Cl2, under inert
atmosphere. After 30 min, the solution was filtered and diethyl ether
was added, leading to the formation of a dark precipitate, which
was filtered, washed with diethyl ether, and dried under vacuum.
Yield: 68%.
1H NMR (400 MHz, CD3CN, 25 °C): δ 1.15 (s, 3H, Pd-Me),
2.54 (s, 3H, MeCN), 4.13 (s, 5H, Cp), 4.64 (br, 2H, C5H4), 5.24
(br, 2H, C5H4), 7.92 (dd, 3JH,H ) 8.4 and 5.2 Hz, 1H, H8), 8.09 (m,
3
2H, H5 and H6), 8.36 (d, JH,H ) 8.5 Hz, 1H, H3 or H4), 8.53 (d,
[Pd(Cl)(Me)(COD)] was prepared from [Pd(OAc)2] in three steps
according to published procedures.13,17 Phosphine 8 was prepared
according to a published procedure.15
1H, H3 or H4), 8.75 (d, 1H, H7), 8.88 (d, 1H, H9) ppm. Anal. Calcd
for C25H22F6FeN3PPd: C, 44.70; H, 3.30; N, 6.26. Found: C, 44.9;
H, 3.0; N, 6.72.
2-ferrocenyl-1,10-phenanthroline, 1. A mixture of 8-amino-7-
quinolinecarbaldehyde (1.09 g, 6.33 mmol), ferrocenyl methyl
ketone (1.44 g, 6.33 mmol), and saturated ethanolic KOH (2 mL)
in absolute EtOH (65 mL) was introduced into a 100 mL round-
bottom flask, equipped with a condenser, a magnetic stirrer, and a
serum cap, under an atmosphere of nitrogen, and the solution was
refluxed for 6 h. The reaction was followed by TLC on neutral
alumina eluting with EtOAc. After cooling, the mixture was
concentrated and diluted with water to produce a white precipitate,
which was extracted with CH2Cl2 (3 × 30 mL). The combined
organic phase was washed with water (2 × 20 mL) and dried over
sodium sulfate, and the solvent was evaporated under reduced
pressure. The residue was purified by flash chromatography with
EtOAc/CH2Cl2, 1:1. Crystallization from diethyl ether gave the pure
compound (1.5 g; 65% yield); mp 198-200 °C.
[Pd(Me)(1)], 4. To a stirred solution of 2 (0.03 g, 0.06 mmol)
in 10 mL of methanol was added, at room temperature, an excess
of sodium acetate (0.024 g, 0.30 mmol). After 2 days, the initially
red solution has turned purple. It was then filtered and the volatiles
were removed under reduced pressure. To the resulting solid was
added dichloromethane, and the mixture was filtered over Celite.
A pure sample of the desired product was obtained by flash
chromatography (ethyl acetate). Yield: 57%.
1H NMR (400 MHz, CDCl3, 25 °C): δ 0.83 (br, 3H, Pd-Me),
4.19 (s, 5H, Cp), 4.64 (t, 3JH,H ) 2.3 Hz, 1H, Hâ of C5H3), 4.71 (d,
3JH,H ) 2.2 Hz, 1H, HR of C5H3), 5.06 (d, 3JH,H ) 2.1 Hz, 1H, Hγ
3
of C5H3), 7.50 (d, JH,H ) 8.51 Hz, 1H, H3 or H4), 7.77 (m, 3H,
H5, H6, and H8), 8.19 (d, 3JH,H ) 8.4 Hz, 1H, H3 or H4), 8.37 (dd,
3JH,H ) 8.2 and 4JH,H ) 1.3 Hz, 1H, H7), 9.03 (dd, 3JH,H ) 4.8 and
4JH,H ) 1.3 Hz, 1H, H9) ppm.
(16) (a) Neve, F.; Crispini, A.; Di Pietro, C.; Campagna, S. Organome-
tallics 2002, 21, 3511. (b) Ghedini, M.; Aiello, I.; Crispini, A.; La Deda,
M. Dalton Trans. 2004, 1386.
(17) (a) Milani, B.; Marson, A.; Zangrando, E.; Mestroni, G.; Ernsting,
J. M.; Elsevier, C. J. Inorg. Chim. Acta 2002, 327, 188. (b) Chatt, L.;
Vallarino, L. M.; Venanzi, L. M. J. Chem. Soc. 1957, 3413.
[Pd(1)(O2CCF3)], 5. [Pd(OAc)2] (0.10 g, 0.45 mmol) was stirred
at room temperature in 10 mL of MeOH. After 10 min, solid 1
(0.185 g, 0.51 mmol) was added and the solution became dark red.
It was then filtered and 1 mL of CF3COOH added to the filtrate,
which immediately became purple and was stirred for 30 min,

Pd Chemistry of 2-Ferrocenyl-1,10-phenanthroline Ligand
Organometallics, Vol. 26, No. 4, 2007 817
1H, CH2), 4.03 (d br, 2JP,H ) 13.5 Hz, 1H, CH2), 4.26 (d, 3JH,H
leading to the precipitation of a solid. The latter was then filtered,
washed with cold MeOH, and dried under vacuum. Crystals suitable
for X-ray crystallography were obtained from CH2Cl2/Et2O.
Yield: 58%.
)
2.2 Hz, 1H, HR of C5H3), 4.63 (br, 1H, Hâ of C5H3), 4.89 (d, 1H,
Hγ of C5H3), 7.40-7.90 (series of m, aromatics and H5, H6), 7.68
(d, 3JH,H ) 6.1 Hz, 1H, H3), 7.93 (d, 3JH,H ) 8.3 Hz, 1H, H8), 8.50
(br, 1H, H4), 8.52 (br, 1H, H7), 8.87 (br, 1H, H9) ppm. 31P{1H}
NMR (161.8 MHz, CDCl3, 25 °C): δ 42.0 (s) ppm. [R]20D +1200
(5 × 10-3 g/100 mL; CHCl3). Anal. Calcd for C52H36F3FeN2O2-
PPd: C, 64.32; H, 3.74; N, 2.88. Found: C, 64.91; H, 3.27; N,
3.35.
1H NMR (400 MHz, CD2Cl2, 25 °C): δ 4.28 (s, 5H, Cp), 4.70
(br, 1H, HR of C5H3), 4.82 (br, 1H, Hâ of C5H3), 4.85 (br, 1H, Hγ
of C5H3), 7.51 (d, 3JH,H ) 8.5 Hz, 1H, H3), 7.79-7.82 (m, 3H, H5,
3
3
H6, and H8), 8.24 (d, JH,H ) 8.78 Hz, 1H, H4), 8.45 (d, JH,H
)
8.06 Hz, 1H, H7), 8.80 (d, JH,H ) 4.64 Hz, 1H, H9) ppm. Anal.
Calcd for C24H15F3FeN2 O2Pd: C, 49.47; H, 2.59; N, 4.81. Found:
C, 51.6; H, 2.11; N, 4.95.
3
[Pd2(1)2(µ-dppe)][O2CCF3]2, 10. To a stirred solution of 5 (0.04
g, 0.07 mmol) in 10 mL of CH2Cl2 was added 0.5 equiv of 1,2-
bis(diphenylphosphino)ethane (dppe) (0.014 g, 0.035 mmol). After
stirring at room temperature for 30 min the volatiles were removed
under reduced pressure. The solid obtained was then washed with
diethyl ether, filtrated, and dried under vacuum. Yield: 71%.
[Pd(1)(NCMe)][PF6], 6. To a stirred solution of 5 (0.03 g, 0.05
mmol) in 10 mL of CH2Cl2 was added an excess of NaPF6 (0.01
g, 0.06 mmol) dissolved in 1 mL of anhydrous MeCN. It was stirred
at room temperature for 3 h and filtrated. Addition of diethyl ether
caused the precipitation of a solid, which was filtrated, washed with
hexane, and dried under vacuum, affording a dark purple crystalline
solid. Crystals suitable for X-ray crystallography were obtained
directly from the synthesis.
1H NMR (400 MHz, CDCl3, 25 °C): δ 2.02 (br, 4H, CH2), 3.69
3
(d, JH,H ) 2.2 Hz, 1H, HR of C5H3), 3.77 (s, 10H, Cp), 3.81 (d,
3JH,H ) 2.2 Hz, 1H, HR of C5H3), 4.33 (br t, 1H, Hâ of C5H3), 4.36
3
(br t, 1H, Hâ of C5H3), 4.62 (d, JH,H ) 2.1 Hz, 1H, Hγ of C5H3),
1H NMR (400 MHz, acetone-d6, 25 °C): δ 4.40 (s, 5H, Cp),
4.64 (d, 3JH,H ) 2.3 Hz, 1H, Hγ of C5H3), 7.21 (d, 3JH,H ) 4.6 Hz,
1H, H9), 7.33 (br, H8), 7.38-7.68 (series of m, aromatics), 7.57
(d, 1H, H3), 7.74-7.96 (m, 4H, H5 and H6), 8.24 (br, 1H, H7),
4.85 (br, 1H, HR of C5H3), 5.01 (br, 1H, Hâ of C5H3), 5.14 (br, 1H,
3
Hγ of C5H3), 7.84 (d, JH,H ) 8.79 Hz, 1H, H3), 8.05-8.12 (m,
3H, H8, H5, and H6), 8.61 (d, 1H, H4), 8.34 (d, 3JH,H ) 7.8 Hz, 1H,
H7), 9.04 (br, 1H, H9) ppm. 1H NMR (400 MHz, CD2Cl2, 25 °C):
3
8.43 (br, 2H, H7 and H4), 8.52 (d, JH,H ) 8.5 Hz, 1H, H4) ppm.
31P{1H} NMR (161.8 MHz, CDCl3, 25 °C): δ 26.6 (s) and 27.1
(s) ppm. Anal. Calc for C74H54F6Fe2N4O4P2Pd2: C, 56.84; H, 3.48;
N, 3.58. Found: C, 57.4; H, 3.29; N, 3.89.
3
δ 2.58 (s, 3H, MeCN), 4.40 (s, 5H, Cp), 7.50 (d, JH,H ) 8.8 Hz,
3
1H, H3), 7.86 (m, 2H, H5 and H6), 7.90 (dd, JH,H ) 8.3 and 4.8
3
3
Hz, 1H, H8), 8.28 (d, 1H, JH,H ) 8.8, H4), 8.52 (dd, JH,H ) 8.3
[Pd2(1)2(µ-dppp)][O2CCF3]2, 11. A procedure similar to that
of the synthesis of 10 was used, using 1,3-bis(diphenylphosphino)-
propane (dppp) instead of dppe. Yield: 76%.
Hz and JH,H ) 1.46, 1H, H7), 8.84 (d, 1H, JH,H ) 4.88 Hz, H9)
ppm. Anal. Calcd for C24H18F6FeN3PPd: C, 43.97; H, 2.77; N,
6.41. Found: C, 44.35; H, 3.09; N, 6.7.
4
3
1H NMR (400 MHz, CDCl3, 25 °C): δ 2.5 and 3.40 (br, 6H,
CH2), 3.71 (br s, 1H, C5H3), 3.76 (s, 10H, Cp), 3.82 (br s, 1 H,
C5H3), 4.32 (br s, 1H, C5H3), 4.37 (br s, 1H, C5H3), 4.63 (br s, 1H,
C5H3), 4.65 (br s, 1H, C5H3), 7.18-8.53 (series of br m, aromatics)
ppm. 1H NMR (400 MHz, dmso-d6, 100 °C): δ 2.5 (br, 2H, CH2),
[Pd(1)(PPh3)][O2CCF3], 7. To a solution of 5 in CDCl3 was
added 1 equiv of solid PPh3. 1H and 31P{1H} NMR spectra recorded
immediately showed the presence of free phosphine (less than 10%)
and unreacted 5. Total conversion occurred after 1 night, affording
7 as the only product observed in solution.
3
3.20 (br m, 4H, CH2), 3.70 (d, JH,H ) 2.2 Hz, 1H, HR of C5H3),
3.72 (d, 3JH,H ) 2.3 Hz, 1H, HR of C5H3), 3.86 (s, 10 H, Cp), 4.38
Synthesis: To a stirred solution of 5 (0.035 g, 0.06 mmol) in 10
mL of CH2Cl2 was added 1 equiv of solid PPh3 (0.016 g, 0.06
mmol). The reaction was monitored by 31P{1H} NMR. When the
spectrum showed complete reaction of the phosphine, the volatiles
were removed under reduced pressure. The solid obtained was then
washed with diethyl ether, filtrated, and dried under vacuum,
affording a dark crystalline solid. Crystals suitable for X-ray
crystallography were obtained from CH2Cl2/Et2O at 6 °C. Yield:
81%.
3
3
(t, JH,H ) 2.5 Hz, 1H, Hâ of C5H3), 4.44 (t, JH,H ) 2.5 Hz, 1H,
Hâ of C5H3), 4.87 (d, 1H, Hγ of C5H3), 4.90 (d, 1H, Hγ of C5H3),
7.17 (d, 3JH,H ) 4.2 Hz, 1H, H9), 7.21 (d, 3JH,H ) 4.1 Hz, 1H, H9),
7.40 (m, 2H, H8), 7.52-7.88 (series of m, aromatics), 7.68 (d, 1H,
H3), 7.77 (d, 1H, H3), 7.90-8.07 (m, 4H, H5 and H6), 8.50 (m, 3H,
one H4 and two H7), 8.59 (d, JH,H ) 8.5 Hz, 1H, H4) ppm. 31P-
3
{1H} NMR (161.8 MHz, CDCl3, 25 °C): δ 26.5 (s) and 27.0 (s)
ppm. Anal. Calcd for C75H56F6Fe2N4O4P2Pd2: C, 57.09; H, 3.58;
N, 3.55. Found: C, 57.55; H, 3.74; N, 3.97.
1H NMR (400 MHz, CDCl3, 25 °C): δ 3.55 (d, 3JH,H ) 2.4 Hz,
1H, HR of C5H3), 3.81 (s, 5H, Cp), 4.46 (t, 3JH,H ) 2.2 Hz, 1H, Hâ
CO/Styrene Copolymerization. The copolymerization reaction
was carried out in a glass reactor (75 mL), equipped with a magnetic
stirrer and a temperature controller. The catalyst (1.27 × 10-5 mol),
1,4-benzoquinone, styrene (10 mL), and 2,2,2-trifluoroethanol were
placed in the reactor, CO was bubbled through the solution for 10
min, then a balloon filled with CO was connected to the reactor
and the system was heated at 30 °C. At the end of the reaction,
after cooling and releasing of the residual gas, the reaction mixture
was poured into methanol (100 mL), causing the precipitation of
the polymer, which was then filtered, washed with methanol, and
dried under vacuum. A 13C NMR spectrum of the polyketones
obtained was recorded in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)
with a small amount of CDCl3 for locking purposes at 100.5 MHz.
Heck Coupling. To a 25 mL Schlenk flask were added catalyst
(3 × 10-3 mmol; 0.1%), triethylamine (0.42 mL, 3.0 mmol),
iodobenzene (2.0 mmol), methyl acrylate (0.27 mL, 3 mmol), and
DMF (10 mL). The mixture was refluxed at 110 °C into an oil
bath. After 14 h the reaction mixture was extracted with dichlo-
romethane (5 mL) and water (10 mL). The organic layer was
washed four times with 10 mL portions of water and dried with
MgSO4. The mixture was then filtered and the dichloromethane
removed in vacuo. A pure product was obtained by flash column
3
3
of C5H3), 4.91 (d, JH,H ) 2.2 Hz, 1H, Hγ of C5H3), 6.85 (d, JH,H
) 4.9 Hz, 1H, H9), 7.46 (dd, 1H, 3JH,H ) 8.0 and 4.9 Hz, H8), 7.55
3
(m, 6H, PPh3), 7.63 (m, 3H, PPh3), 7.74 (d, JH,H ) 8.54 Hz, 1H,
H3), 7.85 (m, 6H, PPh3), 7.98 (dd, 2H, H5 and H6), 8.55 (d, 1H,
H4), 8.62 (d, 1H, H7) ppm. 31P{1H} NMR (109.25 MHz, CDCl3,
25 °C): δ 35.3 (s) ppm. Anal. Calcd for C42H30F3FeN2O2PPd: C,
59.70; H, 3.58; N, 3.32. Found: C, 59.53; H, 3.88; N, 3.18.
[Pd(1)(8)][O2CCF3], 9. To a stirred solution of 5 (0.02 g, 0.034
mmol) in 5 mL of CH2Cl2 was added under argon 1 equiv of solid
8. After stirring at room temperature for 30 min the volatiles were
removed under reduced pressure. The solid obtained was then
washed with diethyl ether, filtrated, and dried under vacuum.
Yield: 77%.
31P{1H} NMR (161.8 MHz, CDCl3, 25 °C): δ 42.0 (s) and 42.5
(s) ppm.
Two successive recrystallizations from chloroform/diethyl ether
(1:1, 3 mL for 10 mg of solid) at 6 °C afforded a pure, dark purple,
solid sample of one of the two diastereoisomers.
3
1H NMR (400 MHz, CDCl3, 25 °C): δ 3.48 (dd, JH,H ) 6.6
2
3
2
and JP,H ) 13.6 Hz, 1H, CH2), 3.64 (dd, JH,H ) 3.9 and JP,H
)
2
12.6 Hz, 1H, CH2), 3.69 (s, 5H, Cp), 3.87 (d br, JP,H ) 12.6 Hz,

818 Organometallics, Vol. 26, No. 4, 2007
Table 2. Crystal Data and Details of Refinements for Compounds 5, 6, and 7
Durand et al.
5
6‚CH2Cl2
7‚CH2Cl2
formula
C24H15F3FeN2O2Pd
582.63
C25H20Cl2F6FeN3PPd
740.56
C43H32Cl2F3FeN2O2PPd
929.83
Mr [g mol-1
]
wavelength [Å]
cryst syst
space group
a [Å]
b [Å]
c [Å]
0.71073
monoclinic
P21/c
11.427(4)
12.338(4)
15.599(5)
90.0
110.56(3)
90.0
2059.1(12)
4
1.54178
monoclinic
P21/n
10.105(3)
22.529(5)
11.948(4)
90.0
96.86(3)
90.0
2700.5(13)
4
0.71073
Triclinic
P1h
10.708(3)
10.965(4)
17.713(4)
102.76(3)
90.78(3)
98.74(2)
2002.4(10)
2
R [deg]
â [deg]
γ [deg]
volume [Å3]
Z
D
calcd [g cm-3
]
1.879
1.631
1152
1.821
12.639
1464
1.542
1.038
936
µ [mm-1
F(000)
]
θ range [deg]
2.16-27.10
5.42-56.05
2.02-26.49
no. of reflns collected
no. of unique reflns
Rint
32 782
11 735
16 790
4395
0.0634
3283
0.0419
7015
0.0417
obsd I > 2σ[I]
3445
298
1.025
0.0353
0.0942
0.919, -0.643
2593
389
1.056
0.0611
0.1584
0.791, -0.728
3271
494
0.914
0.0731
0.2034
1.345, -0.673
no. of params
goodness of fit (F2)
R1 [I > 2σ[I]a
b
wR2
∆F [e Å-3
]
b
2
2
2
a R1 ) ∑ ||Fo| - |Fc||/∑|Fo|. wR2 ) [∑w(Fo - Fc )2/∑w(Fo )2]1/2
.
Further details of the crystal structure determination have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication. CCDC numbers 614894-614896 for
complexes 5, 6, and 7, respectively, contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from the Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
chromatography on silica gel with a mixture of hexane/diethyl ether
as eluent (12:1, v/v). The conversion was determined by GC and
the identity of the product was confirmed by 1H NMR comparison
with the authentic sample.
Crystallographic Data Collection and Refinements. Data
collections of complexes 5 and 7 were carried out at 293(3) K using
Mo KR radiation (λ ) 0.71073 Å) on a Nonius DIP-1030H system,
and that of compound 6 on a Bruker-Nonius FR591 rotating anode
(Cu KR) equipped with a KappaCCD detector. Cell refinement,
indexing, and scaling of the data set were performed using the
programs Mosflm,18 Denzo, and Scalepack.19 In 6 the equatorial
PF6- fluorine atoms were found disordered over two positions along
the F-P-F axial direction (occupancies refined to 0.70/0.30). A
lattice CH2Cl2 molecule was detected in the ∆F map of 6 and 7; in
the latter structure the solvent is disordered over two positions
(occupancies refined to 0.53/0.47, H atoms not included). All the
structures were solved by direct method and successive Fourier
analyses and refined by the full-matrix least-squares method based
on F2 with all observed reflections.20 Crystal data for the structures
reported are summarized in Table 2. The calculations were
performed using the WinGX System, Ver. 1.70.00.21
Acknowledgment. This work was supported by Ministero
dell’Istruzione, dell’Universita` e della Ricerca (MIUR-Rome;
PRIN No. 2005035123) and by the European Network “PAL-
LADIUM” (5th Framework Program, contract No. HPRN-CT-
2002-00196). S.G. thanks Prof. Barbara Floris (Universita` di
Roma 2 “Tor Vergata”) for providing a generous sample of
acetyl ferrocene. B.M. acknowledges Engelhard Italia for a
generous gift of [Pd(OAc)2].
Supporting Information Available: 1H NOE spectrum of 2
1
(Figure S1), comparison of the H NMR spectra of 2, 3, 4, and 5
(Figure S2), and full details of crystallographic analyses of 5, 6,
and 7 in CIF format. This material is available free of charge via
the Internet http://pubs.acs.org.
(18) Collaborative Computational Project, Number 4. Acta Crystallogr.,
Sect. D 1994, 50, 760.
OM060703A
(19) Otwinowski, Z.; Minor, W. In Processing of X-ray Diffraction Data
Collected in Oscillation Mode; Methods in Enzymology, Vol. 276: Mac-
romolecular Crystallography, part A; Carter, C. W. Jr., Sweet, R. M., Eds.;
Academic Press: New York, 1997; pp 307-326.
(20) Sheldrick, G. M. SHELX97 Programs for Crystal Structure Analysis
(Release 97-2); University of Go¨ttingen: Germany, 1998.
(21) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.