trans-Spanning ferrocene amidodiphosphine ligand: Synthesis, palladium complexes and catalytic use in Suzuki-Miyaura cross-coupling

Article abstract of DOI:10.1016/j.jorganchem.2009.04.039

Amide coupling between [2-(diphenylphosphino)phenyl]methylamine and 1′-(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) afforded a novel diphosphine-amide, 1-{N-[(2-(diphenylphosphino)phenyl)methyl]carbamoyl}-1′-(diphenylphosphino)ferrocene (1), which was subsequently studied as a ligand for palladium(II) complexes. Depending on the metal precursor, the following complexes were isolated: [PdCl₂(1-κ²P,P′)] (2), [PdCl(Me)(1-κ²P,P′)] (3), [(μ-1){PdCl₂(PBu₃)}₂] (4) and [(μ-1){PdCl(L^NC)}₂] (L^NC = 2-[(dimethylamino-κN)methyl]phenyl-κC¹), featuring this ligand either as a trans-chelating or as a P,P′-bridging donor. The crystal structure of 2·1.25CH₂Cl₂ was established by X-ray crystallography, corroborating that 1 coordinates as a trans-spanning diphosphine without any significant distortion to the coordination sphere. Complex 2 together with a catalyst prepared in situ from 1 and palladium(II) acetate were tested in Suzuki-Miyaura reaction of aryl bromides with phenylboronic acid in dioxane.

Full text of DOI:10.1016/j.jorganchem.2009.04.039

Journal of Organometallic Chemistry 694 (2009) 2987–2993
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
trans-Spanning ferrocene amidodiphosphine ligand: Synthesis, palladium
complexes and catalytic use in Suzuki–Miyaura cross-coupling
*
ˇ
ˇ
ˇ
ˇ
Petr Štepnicka , Martin Krupa, Martin Lamac, Ivana Císarová
Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 12840 Prague, Czech Republic
a r t i c l e i n f o
a b s t r a c t
Amide coupling between [2-(diphenylphosphino)phenyl]methylamine and 10-(diphenylphosphino)ferro-
Article history:
Received 6 January 2009
Received in revised form 31 March 2009
Accepted 29 April 2009
cene-1-carboxylic acid (Hdpf) afforded
a
novel diphosphine-amide, 1-{N-[(2-(diphenylphos-
phino)phenyl)methyl]carbamoyl}-10-(diphenylphosphino)ferrocene (1), which was subsequently
studied as a ligand for palladium(II) complexes. Depending on the metal precursor, the following
Available online 7 May 2009
complexes were isolated: [PdCl2(1-j2P,P0)] (2), [PdCl(Me)(1-j2P,P0)] (3), [(
[(l jN)methyl]phenyl-j
l
-1){PdCl2(PBu3)}2] (4) and
-1){PdCl(LNC)}2] (LNC = 2-[(dimethylamino- C1), featuring this ligand either as a
Keywords:
trans-Spanning diphosphines
Ferrocene
Amidophosphines
Palladium
Structure elucidation
Suzuki–Miyaura reaction
trans-chelating or as a P,P0-bridging donor. The crystal structure of 2ꢀ1.25CH2Cl2 was established by
X-ray crystallography, corroborating that 1 coordinates as a trans-spanning diphosphine without any sig-
nificant distortion to the coordination sphere. Complex 2 together with a catalyst prepared in situ from 1
and palladium(II) acetate were tested in Suzuki–Miyaura reaction of aryl bromides with phenylboronic
acid in dioxane.
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
geously utilised in the preparation of N-functionalised amides.
Such donors are highly structurally versatile and potentially mul-
Bidentate ligands capable of traversing trans coordination sites
have originally attracted attention as chemical curiosities. Later on,
however, they proved practically useful for the elucidation of li-
gand steric effects in coordination compounds, for fundamental
studies on metal-mediated reactions and in catalysis. The most fre-
quently encountered trans-spanning ligands are undoubtedly
diphosphines, whose donor moieties are pre-arranged with an
aid of an organic backbone into positions appropriate for the for-
mation of trans-chelates [1]. Less attention has been paid to other
symmetric ligands (e.g., to N,N-type [2] and bis-carbene ligands
[3]) and, particularly, to their donor-unsymmetric counterparts
(e.g., to P,N-donors [4]).
While extending our studies on ferrocene phosphinocarboxylic
acids [5,6], we recently turned also to their carboxamide deriva-
tives. So far, we have demonstrated that even simple phosphino-
ferrocene carboxamides are versatile ligands for coordination
chemistry and catalysis [6b,6g,7], and valuable organometallic syn-
thetic building blocks [8]. Ferrocene phosphinocarboxylic amides
are usually readily accessible by reaction of the appropriate amines
with phosphinocarboxylic acids in the presence of peptide cou-
pling agents or, alternatively, via active phosphinocarboxylic pen-
tafluorophenyl esters [7–9]. As these methods are relatively mild
and tolerate numerous functional groups, they can be advanta-
tidentate, thus markedly widening the spectrum of accessible fer-
rocene phosphinocarboxamides as well as their application field,
particularly towards coordination chemistry and catalysis. Validity
of this approach has been already demonstrated by the synthesis of
ferrocene phosphinocarboxamides from pyridyl-substituted [7a,d]
and 2-hydroxyethyl amines [10], and from amino acid esters [11].
During our studies on the former ligands, we found that N-(pyr-
id-2-yl)methyl amide I (see Chart 1) reacts with [PdCl2(cod)]
(cod = g2 2-cycloocta-1,5-diene) to give trans-chelate or bis-
:g
phosphine palladium(II) complexes depending on the metal-to-li-
gand ratio [7a]. This property led us to design an analogue to amide
I, in which the pyridine nitrogen is replaced with a ‘‘C-PPh2” moi-
ety (compound 1). Herein, we report the preparation of this novel
diphosphine-amide and several palladium complexes thereof. We
also describe the crystal structure of [PdCl2(1-j2P,P0)] featuring this
diphosphine as a trans-chelating donor and preliminary results of
catalytic testing of this complex in Suzuki–Miyaura cross-coupling.
2. Results and discussion
2.1. Synthesis and spectroscopic characterisation of the ligand
Diphosphine-amide 1 was synthesised by amide coupling of
[2-(diphenylphosphino)phenyl]methylamine to 10-(diphenylphos-
phino)ferrocene-1-carboxylic acid (Hdpf) in the presence of
1-hydroxybenzotriazole (HOBt) and N-[3-(dimethylamino)
* Corresponding author. Fax: +420 221 951 253.
ˇ
ˇ
E-mail address: stepnic@natur.cuni.cz (P. Štepnicka).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.04.039

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P. Štepnicka et al. / Journal of Organometallic Chemistry 694 (2009) 2987–2993
PPh
2
Ph
X
Ph
PPh
2
P
Fe
Cl
Ph
Fe
Pd
O
1
O
O
[PdCl(X)(cod)]
Fe
C
– cod
C
P
HN
C
HN
Ph
I
1
N
HN
PPh
2
2 (X = Cl)
3 (X = Me)
Chart 1.
Scheme 2.
propyl]-N0-ethylcarbodiimide hydrochloride (EDCꢀHCl; Scheme 1).
Isolation by column chromatography followed by crystallisation
from ethyl acetate-hexane afforded 1 as an air-stable, orange solid
in a 67% yield.
at positions similar to those of free 1, thereby ruling out the
involvement of the amide moiety in coordination. On the other
hand, the 31P{1H} NMR spectra display pairs of doublets due to
the interacting non-equivalent phosphorus atoms (2JPP = 572 Hz
for 2, 437 Hz for 3), that are shifted to lower fields compared with
the free ligand. Whereas the 1H NMR spectrum of 2 displays four
resonances attributable to the ferrocene CH groups (AA0BB0 and
AA0BB0X spin systems; A, B = 1H, X = 31P), the ferrocene protons in
the spectrum of complex 3 are observed non-degenerate (eight
resonances) because of a lowered molecular symmetry.
Compound 1 was characterised by conventional spectroscopic
methods (NMR, IR and MS) and by combustion analysis. In IR spec-
tra, it showed characteristic strong amide bands at 1632 and
1553 cmꢁ1 1H and 13C{1H} NMR spectra of 1 were consistent with
.
the formulation, combining the signals due to the 1,10-disubsti-
tuted ferrocene unit, the amide pendant (CONHC6H4) and two
chemically different PPh2 groups at the expected positions. The
amide proton was observed as a methylene-coupled triplet at dH
5.94 whereas its bonded methylene resonated at dH 4.69, being ob-
served as a double doublet due to coupling with the amide proton
It is also noteworthy that 1H NMR spectrum of 2 recorded at
room temperature displays some signals markedly broadened. A
variable temperature (VT) NMR study (Fig. 1) confirmed such sig-
nal broadening to reflect a molecular dynamics slow at the NMR
time scale. Whereas warming to 50 °C caused a sharpening of the
proton resonances (except for one ferrocene CH signal at dH ca.
4.54 which remained broad even at this temperature), cooling to
0 °C and further down to ꢁ25 °C resulted in broadening of the res-
onances, particularly those attributable to the ferrocene unit. The
observed dynamic behaviour apparently results from a limited
conformational mobility of the ligand molecule imparted by its
trans-chelate coordination.
4
and the proximal phosphorus atom (3JHH = 6.1, JPH = 1.1 Hz). In
13C{1H} NMR spectrum, the methylene group was observed as a
phosphorus-coupled doublet at dC 42.2 (3JPC = 21 Hz) while the car-
bonyl group signal was found at dC 169.34 (cf. dC 177.2 for Hdpf
[12]). Finally, the 31P{1H} NMR spectrum comprised two sharp
singlets at dP ꢁ14.7 and ꢁ17.0 attributable to benzene- and ferro-
cene-bound PPh2 groups, respectively. The position of the latter
signal corresponds with that of the parent acid (Hdpf: dP ꢁ17.6
[12]) and its amides [7,8].
In contrast to its PMe3-analogue, complex [{Pd(l-Cl)Cl(PBu3)}2]
2.2. Preparation of palladium(II) complexes
reacted with 1 to give the expected bridge-cleavage product 4
(Scheme 3). Such difference in reactivity can be attributed to unlike
steric and electronic properties of the two phosphines. Tributyl-
phosphine is not only a stronger donor than PMe3 but also provides
a better steric protection to the metal centre, which both make any
intramolecular ligand substitution more difficult. Another dipalla-
dium complex involving diphosphine 1 as a P,P0-bridging ligand,
compound 5, was obtained by bridge-splitting reaction from the
The reaction between equimolar amounts of 1 and [PdCl2(cod)]
gave complex [PdCl2(1)] (2) featuring the bis-phosphine as a trans-
chelating ligand (Scheme 2). A similar reaction with [PdCl(Me)
(cod)] afforded an analogous complex [PdCl(Me)(1)] (3) (Scheme
2). Surprisingly, complexes 2 and 3 resulted also when 1 was re-
acted with the respective dimers [{Pd(l-Cl)(X)(PMe3)}2] (X = Cl,
Me). Formation of the chelated monopalladium complexes from
the chloride-bridged dinuclear precursors is most likely a stepwise
process, consisting of primary bridge-cleavage reaction and a sub-
sequent intramolecular, chelate-assisted substitution of the PMe3
ligand [13].
Complexes 2 and 3 tend to retain solvents in their structures,
crystallising as dichloromethane adducts. Their formulation was
established from IR, electrospray (ESI) MS and NMR spectra, and
confirmed by elemental analyses. Besides, the solid-state structure
of 2 was established by X-ray diffraction analysis (vide infra). Spec-
tral data of 2 and 3 clearly indicate that ligand 1 coordinates as a
chelating diphosphine. The amide bands in IR spectra are observed
dimer
[{Pd(
l
-Cl)(LNC)}2],
where
LNC = 2-[(dimethylamino-
jN)methyl]phenyl-
j
C1 (Scheme 3). Similarly to their monopalladi-
um counterparts, complexes 4 and 5 show the 31P NMR signals
shifted to lower fields compared to free 1 though as singlets owing
to an absence of a scalar P–P coupling. The IR spectra of 4 and 5
suggested the presence of uncoordinated amide moieties.
2.3. The crystal structure of complex 2
The solid-state structure of complex 2 has been determined for
its solvate 2ꢀ1.25CHCl3. Views of the complex molecule are shown
in Fig. 2. Selected geometric data are listed in Table 1. At first sight,
the structure determination corroborates the expected trans-che-
late coordination of the diphosphine ligand. The Pd-donor bond
lengths correspond well with the distances reported for trans-
[PdCl2L2] complexes, where L is P-monodentate Hdpf [14] or
Ph2PfcCONHCH2(C5H4N-2) (fc = ferrocene-1,10-diyl) [7a]. As indi-
cated by the interligand angles, the diphosphine spans the trans
positions with only a minor distortion of the coordination plane
around palladium. The ligand bite angle P1-Pd-P(2) is 171.91(3)°,
not far from the ideal 180°. A minor deviation from the regular
geometry can be demonstrated also by the difference in the
Cl(n)-Pd-P(1,2) angles (4.3° for n = 1; 5.4° for n = 2) or, alternatively
PPh
2
PPh
PPh
2
2
NH
2
Fe
Fe
EDC·HCl/HOBt
O
CO H
C
2
HN
1
Hdpf
PPh
2
Scheme 1.

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P. Štepnicka et al. / Journal of Organometallic Chemistry 694 (2009) 2987–2993
2989
Fig. 1. VT 1H NMR spectra of complex 2 in the region of the aromatic and NH (left) and cyclopentadienyl and CH2 protons (right). A and M denote the signals due to amide NH
and NH-bonded methylene protons, respectively. The asterisks indicate residual solvent signals (CH2Cl2 and CHCl3).
the amide moiety whilst the phosphorus atoms decline in the
opposite direction, all deviating from the common least-squares
{PdCl2P2} plane by ca. 0.16 Å. Yet, the sum of the interligand angles
(361.1°) rules out any pronounced tetrahedral deformation.
The {PdCl2P2} plane and the Cp(1) ring are mutually rotated by
57.2(1)° which, together with the bending of the chloride atoms,
aids the formation of intramolecular hydrogen bonds N–
H(1N)ꢀꢀꢀCl(2) [NꢀꢀꢀCl(2) = 3.439(3) Å, N–H(1N)ꢀꢀꢀCl(2) = 157°]. Nota-
bly, the chelating ligand is flexible enough to allow for a staggered
conformation of the ‘PC3’ units, which likely represents the least
sterically congested orientation of the two bulky phosphine moie-
ties (Fig. 2b). The ferrocene moiety displays nearly identical Fe-ring
centroid distances and a tilt of 4.6(2)°. Conformation of the 1,10-
disubstituted ferrocene unit is close to syn-eclipsed with the tor-
sion angle C(1)–Cg(1)–Cg(2)–C(6) being 68° (cf. the ideal value of
72°). Despite the intramolecular hydrogen bonding interaction,
the amide {C(11)ON} moiety and the Cp(2) ring are nearly coplanar
(dihedral angle 5.1(4)°). On the other hand, the C(25–30) benzene
ring is practically perpendicular to both the coordination plane
Cl
L Pd
Ph
P
n
Ph
Fe
O
Cl
Cl
Cl
C
L Pd
n
PdL + 1
n
Ph PdL
HN
n
P
Ph
4, 5
[PdL ] = PdCl(PBu ) (4), Pd{2-(Me NCH )C H } (5)
n
3
2
2
6 4
Scheme 3.
by the angle subtended by the Cl(1)ꢀꢀꢀCl(2) and P(1)ꢀꢀꢀP(2) vectors
being 87.55(2)°. When viewed along the P(1)ꢀꢀꢀP(2) line (Fig. 2b),
the chloride ligands are observed somewhat displaced towards
Fig. 2. PLATON plots of the complex molecule in the crystal structure of 2ꢀ1.25CHCl3: (a) a general view, and (b) a view in the P(1)ꢀꢀꢀP(2) direction. Displacement ellipsoids
enclose the 30% probability level. The intramolecular hydrogen bond N–H(1N)ꢀꢀꢀCl(2) is indicated with a dashed line.

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P. Štepnicka et al. / Journal of Organometallic Chemistry 694 (2009) 2987–2993
Table 1
Table 2
Selected distances and angles for 2ꢀ1.25 CHCl3 (in Å and °).a
Application of 1 to Suzuki–Miyaura cross-coupling of aryl bromides.a
Distances
Angles
Substrate (Y)
Conversion to biphenyl 8
Pd–Cl(1)
Pd–Cl(2)
Pd–P(1)
2.2932(8)
2.3074(8)
2.3321(7)
2.3496(9)
1.656(1)
1.663(2)
1.235(4)
1.344(4)
1.467(4)
1.800(3)
1.815(3)
1.826(3)
1.820(3)
1.827(3)
1.829(3)
Cl(1)–Pd–P(1)
Cl(1)–Pd–P(2)
Cl(2)–Pd–P(1)
Cl(2)–Pd–P(2)
\Cp(1), Cp(2)
O–C(11)–N
87.61(3)
91.95(3)
93.50(3)
88.07(3)
4.6(2)
123.0(3)
122.5(3)
109.9(2)
122.7(3)
4.8(5)
175.0(3)
107.4(1)–119.3(1)
103.7(1)–105.3(1)
109.0(1)–118.7(1)
101.71(1)–106.5(1)
2
Pd(OAc)2-1b
Y = NO2 (7a)
Y = C(O)Me (7b)
Y = OMe (7c)
Y = Me (7d)
Quant.
Quant.
83
Quant.
Quant.
78
Pd–P(2)
Fe–Cg(1)
Fe–Cg(2)
C(11)–O
C(11)–N
N–C(24)
P(1)–C(1)
P(1)–C(12)
P(1)–C(18)
P(2)–C(26)
P(2)–C(31)
P(2)–C(37)
93
85
a
C(11)–N–C(24)
N–C(24)–C(25)
C(24)–C(25)–C(26)
O–C(11)–N–C(24)
C(24)–C(25)–C(26)–P(2)
Pd–P(1)–Cb
The reactions were performed with 0.5 mol.% of the catalyst and 1.5 equiv. of
PhB(OH)2 at 90 °C for 18 h. Conversions were determined from integration of 1H
NMR spectra and are an average of two independent runs. For further details, see
Section 4.
b
Catalyst generated in situ.
C–P(1)–Cc
Pd–P(2)–Cd
C–P(2)–Ce
perature caused the coupling reaction to stop. After 18 h, the in situ
catalyst (1/Pd(OAc)2) gave the coupling product 8d with ca. 5%
conversion while no coupling product was detected when complex
2 was used as the catalyst. Control experiments performed in par-
allel without added mercury proceeded normally.
a
Definition of the ring planes: Cp(1) = C(1–5), Cp(2) = C(6–10). Cg(1) and Cg(2)
denote the respective centroids.
b
The range of Pd–P(1)–C(1,12,18) angles.
The range of C(1)–P(1)–C(12,18) and C(12)–P(1)–C(18) angles.
The range of Pd–P(2)–C(26,31,37) angles.
The range of C(26)–P(2)–C(31,37) and C(31)–P(2)–C(37) angles.
c
d
e
3. Conclusions
Amidophosphine 1 is readily accessible from amide coupling of
10-(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) with
[2-(diphenylphosphino)phenyl]methylamine. The particular dis-
position of the donor atoms and limited mobility of the molecular
scaffold enable this unsymmetric P,P-donor to form trans-chelate
or bridged dinuclear complexes with palladium(II) in dependance
on the metal source. The formation of trans-chelates was shown
to proceed either directly or via ligand-displacement route. As evi-
denced by the structural data for 2 the diphosphine-amide coordi-
nates to palladium without any significant deformation of the
coordination environment around the central atom. Both the de-
fined complex 2 and the 1-Pd(OAc)2 system catalyse Suzuki–Miya-
ura cross-coupling of aryl bromides and phenylboronic acid to give
the corresponding biphenyls.
(dihedral angle 86.8(1)°) and the Cp(2) ring (dihedral angle
84.0(2)°).
2.4. Catalytic experiments
Both the defined complex 2 and a catalyst generated in situ by
mixing ligand 1 with the equimolar amount of palladium(II) ace-
tate have been tested in Suzuki–Miyaura cross-coupling [15] of
phenylboronic acid to give 4-substituted aryl bromides (Scheme
4). The reactions were performed with 0.5 mol.% palladium pre-
catalyst using dioxane as the solvent at 90 °C for 18 h.
The data collected in Table 2 demonstrate that both catalysts
efficiently promote the coupling reaction, the in situ generated
pre-catalyst giving only slightly lower conversions. The reactions
performed with activated aryl halides (7a,b) proceed quantita-
tively whereas those involving derivatives bearing electron-donat-
ing groups (OMe and Me) gave somewhat lower but still very good
conversions. Although the current results may not be astonishing
in view of the recently developed, highly active cross-coupling cat-
alysts [15], they clearly indicate that the trans-coordination prefer-
ence of the diphosphine ligand does not compromise the coupling
reaction (i.e., it does not prevent the formation of catalytically ac-
tive, presumably Pd(0) species) [1a,16]. In view of the previous
studies on Suzuki–Miyaura reactions catalysed with Pd-complexes
with organic trans-chelating diphosphines, the catalytic activity of
1-based systems could be explained by trans-to-cis isomerisation
during catalyst activation, by partial dissociation of the bidentate
ligand (open-arm mechanism) or by formation of some dinuclear
intermediates [17]. Alternative rationalisation can be sought in
the formation of fine metal particles (particularly at elevated tem-
peratures) that were shown to efficiently promote the cross-cou-
pling reactions [18]. The latter explanation seems to be
supported by mercury poisoning tests [19]. Addition of mercury
to the reaction system after stirring for 5 min at the reaction tem-
4. Experimental
4.1. Materials and methods
The syntheses were performed under argon atmosphere with an
exclusion of the direct daylight. Dichloromethane was pre-dried by
standing over anhydrous potassium carbonate and then distilled
from calcium hydride under argon. Dioxane was dried with
sodium metal and distilled under argon. [2-(Diphenylphosphino)
phenyl]methylamine [20] was prepared by reduction of 2-
(diphenylphosphino)benzonitrile [21]. Hdpf [12], [PdCl2(cod)]
(cod = g2
[{Pd( -Cl)(Me)(PMe3)}2] [13], [{Pd(
Bu) [24], and [{Pd(
-Cl)(LNC)}2] [25] were prepared by the litera-
:g
2-cycloocta-1,5-diene) [22], [PdCl(Me)(cod)] [23],
l
l-Cl)Cl(PR3)}2] (R = Me and
l
ture procedures. Other chemicals (Lachema, Fluka) and solvents
used for crystallisations and chromatography (Penta) were used
without purification.
NMR spectra were measured with a Varian Unity Inova spec-
trometer (1H, 399.95; 13C, 100.58; 31P, 161.90 MHz) at 25 °C unless
indicated otherwise. Chemical shifts (d) are given relative to inter-
nal tetramethylsilane (13C and 1H) or to external 85% aqueous
H3PO4 (
31P), all set to 0 ppm. Signals of residual solvents (if appli-
[Pd]
base
cable) are omitted from the signal list. IR spectra were recorded
with an FT IR Nicolet Magna 650 spectrometer. Positive-ion elec-
trospray (ESI+) mass spectra were recorded on a Bruker Esquire
3000 instrument. The samples were dissolved in chloroform or
dichloromethane and the solution was diluted with methanol in
large excess. Fast atom bombardment (FAB) mass spectra were
PhB(OH)
+
Br
Y
Y
2
7a-d
8a-d
Scheme 4. Suzuki–Miyaura cross-coupling of aryl bromides 7a–e to give substi-
tuted biphenyl 8a–e (Y = NO2 (a), Ac (b), OMe (c), and Me (d)).

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P. Štepnicka et al. / Journal of Organometallic Chemistry 694 (2009) 2987–2993
2991
recorded on a ZAB EQ spectrometer in 3-nitrobenzylalcohol matrix.
The melting points were determined on a Kofler block and are
uncorrected.
1184 (m), 1168 (m), 1095 (s), 1037 (m), 1026 (m), 831 (m), 767
(s), 748 (vs), 692 (vs), 516 (vs), 503 (s), 468 (m). FAB+ MS: m/z
865 (M+), 828 ([MꢁCl]+), 792 ([Mꢁ2ClꢁH]+), 737 (elemental com-
position of the fragments was confirmed by a comparison of exper-
imental and theoretical isotopic patterns). Anal. Calc. for
C42H35P2FePdCl2NOꢀ2CH2Cl2 (1034.7): C, 51.07; H, 3.80; N, 1.35.
Found: C, 51.30; H, 3.62; N, 1.27%.
4.2. Preparation of 1-{N-[(2-(diphenylphosphino)-
phenyl)methyl]carbamoyl}-10-(diphenylphosphino)ferrocene (1)
1-Hydroxybenzotriazole (297 mg, 2.2 mmol) was added to a
solution of Hdpf (828 mg, 2.0 mmol) in dry dichloromethane
(10 mL). The mixture was cooled in an ice bath and treated with
N-{3-(dimethylamino)propyl}-N0-ethylcarbodiimide hydrochloride
(EDCꢀHCl; 422 mg, 2.2 mmol), whereupon the solid triazole quickly
dissolved to give an orange red solution. After stirring for 30 min at
0 °C, a solution of [2-(diphenylphosphino)phenyl]methylamine
(640 mg, 2.2 mmol) in dichloromethane (5 mL) was introduced
and the reaction solution was stirred at room temperature over-
night. Then, it was washed successively with 3 M HCl, saturated
aqueous NaHCO3 and brine (50 mL each), dried over MgSO4, and
evaporated under reduced pressure. The yellow orange residue
was purified by column chromatography (silica gel, methanol–
dichloromethane 1:20, v/v). The first orange band due to the amide
was collected and evaporated under vacuum to give an orange so-
lid. Subsequent recrystallisation from ethyl acetate–hexane affor-
ded analytically pure 1 as a yellow orange microcrystalline solid.
Yield: 0.923 g (67%).
Route B: [{Pd(
(9.0 mg, 0.013 mol) were dissolved in dichloromethane (2 mL).
The resulting solution was stirred for 1 h, filtered (PTFE 0.45 m)
l-Cl)Cl(PMe3)}2] 6.6 mg (13 lmmol) and 1
l
l
and then evaporated under reduced pressure. NMR analysis
showed the presence of complex 2 contaminated with minor
amounts of [PdCl2(PMe3)2], analysing as follows: 1H NMR (CDCl3):
2
d 1.46 (d, JPH = 3.6 Hz, PMe3); 31P{1H} NMR (CDCl3): d ꢁ10.6 (s).
4.4. Preparation of complex 3
Route A: [PdCl(Me)(cod)] (14.7 mg, 50
mol) were dissolved in dichloromethane (5 mL). The mixture
was stirred for 45 min and filtered (PTFE syringe filter, 0.45
lmol) and 1 (34.4 mg,
50
l
lm
pore size). Subsequent layering with hexane and crystallisation
at ꢁ18 °C for several days gave the product as an orange solid,
which was filtered off, washed with hexane and dried under vac-
uum. Yield of 3ꢀ1/2CH2Cl2: 31 mg (70%).
Route B: [{Pd(l-Cl)(Me)(PMe3)}2] (11.7 mg, 25 lmol) and 1
M.p. 102–103 °C (ethyl acetate–hexane). 1H NMR (CDCl3): d
4.05 (apparent q, J ꢂ 2 Hz, 2 H, fc), 4.14 (apparent t, J ꢂ 2 Hz, 2H,
fc), 4.28 (apparent t, J ꢂ 2 Hz, 2H, fc), 4.33 (apparent t, J ꢂ 2 Hz,
(17.2 mg, 25 lmol) were dissolved in dichloromethane (3 mL).
The resulting solution was stirred for 1 h, filtered (PTFE syringe fil-
ter), and the filtrate layered with hexane. Crystallisation by diffu-
sion at ꢁ18 °C for several days afforded the product as orange
crystals, which were filtered off, washed with hexane and dried
in air. Yield of 3ꢀ1/2CH2Cl2: 14 mg (63%).
3
4
2H, fc), 4.69 (dd, JHH = 6.1 Hz, JPH = 1.1 Hz, 2H, CH2), 5.94 (t,
3JHH = 6.1 Hz, 1H, NH), 6.89 (ddd, J ꢂ 7.7, 4.6, 1.4 Hz, 1H, C6H4),
7.18 (td, J ꢂ 7.5, 1.5 Hz, 1H, C6H4), 7.24–7.38 (m, 21H, C6H4 and
2ꢃ PPh2), 7.51 (ddd, J ꢂ 7.7, 4.4, 1.3 Hz, 1H, C6H4). 13C{1H} NMR
Analytical data for 3ꢀ1/2CH2Cl2. 1H NMR (CDCl3): d 0.10 (t,
3JPH = 6.1 Hz, 3 H, PdCH3), 3.77 (br s, 1 H, fc), 4.07 (m, 1 H, fc),
4.23 (br s, 1 H, fc), 4.31, 4.43 (2ꢃ m, 1 H, fc), 4.68 (d, 2JHH = 13.8 Hz,
3
(CDCl3): d 42.20 (d, JPC = 21 Hz, CH2), 69.10 (fc CH), 71.63 (fc
CH), 72.90 (d, JPC = 4 Hz, fc CH), 74.12 (d, JPC = 14 Hz, fc CH), 75.04
1
2
(d, JPC = 14 Hz, fc C-P), 76.46 (fc C-CONH), 127.83 (C6H4 CH),
1 H, NHCH2), 4.74, 5.02 (2ꢃ m, 1 H, fc), 5.09 (br dd, JHH = 13.8 Hz,
3
3
128.21 (d, JPC = 7 Hz, PPh2 CHm), 128.70 (d, JPC = 8 Hz, PPh2
CHm), 128.80, 129.04 (2ꢃPPh2 CHp); 129.42 (C6H4 CH), 129.80 (d,
3JHH ca. 8.5 Hz, 1 H, NHCH2), 5.85 (m, 1 H, fc), 6.93, 7.11 (2ꢃ m, 1
H, C6H4), 7.22–7.62 (m, 20 H, 2ꢃ PPh2), 8.07 (m, 2 H, C6H4), 8.31
2
3
JPC = 5 Hz, C6H4 CH), 133.43, 133.93 (2ꢃ JPC = 20 Hz, PPh2 CHo);
(d, JHH ca. 8.5 Hz, 1 H, NH). 31P{1H} NMR (CDCl3): d 14.6 and
1
2
135.54 (d, JPC = 13 Hz, C6H4 Cipso), 136.03, 138.54 (2ꢃ JPC = 10 Hz,
23.2 (2ꢃ d, JPP = 437 Hz). IR (Nujol):
m mNH), 1649
/cmꢁ1 3300 (w,
PPh2 Cipso); 142.78 (d, JPC = 24 Hz, C6H4 Cipso), 169.34 (CONH). One
signal due to CH of C6H4 was not clearly identified, being probably
obscured by the resonance of the PPh2 group (d ca. 133.5). 31P NMR
(s, amide I), 1626 (vs, amide I), 1524 (vs, amide II), 1479 (m),
1436 (s), 1306 (w), 1281 (m), 1199 (w), 1185 (m), 1164 (w),
1102 (w), 1087 (m), 1030 (w), 844 (w), 832 (w), 761 (s), 746
(vs), 694 (s), 516 (vs), 507 (vs), 501 (s), 469 (m). Anal. Calc. for
C43H38P2FePdClNOꢀ1/2CH2Cl2 (886.8): C, 58.91; H, 4.43; N. 1.58.
Found: C, 59.04; H, 4.53; N, 1.54%.
(CDCl3): d ꢁ14.7 (s), ꢁ17.0 (s). IR (Nujol):
m mNH),
/cmꢁ1 3239 (br m,
1742 (w), 1632 (vs, amide I), 1553 (vs, amide II), 1435 (s), 1311 (s),
1269 (m), 1194 (w), 1179 (m), 1161 (m), 1092 (w), 1030 (m), 833
(m), 748 (vs), 742 (vs), 697 (vs), 504 (s), 480 (m), 452 (m) cmꢁ1
.
Anal. Calc. for C42H35FeNOP2 (687.5): C, 73.37; H, 5.13; N. 2.04.
Found: C, 72.99; H, 5.08; N, 1.92%.
4.5. Preparation of complex 4
[{Pd(
were dissolved in dichloromethane (2 mL). The resulting solution
was stirred for 1 h, filtered (PTFE 0.45 m syringe filter) and then
l-Cl)Cl(PBu3)}2] (9.9 mg, 13 lmol) and 1 (9.0 mg, 13 lmol)
4.3. Preparation of complex 2
l
Route A: [PdCl2(cod)] (7.1 mg, 25
mol) were dissolved in dichloromethane (3 mL). The resulting
solution was stirred for 45 min and filtered through a PTFE syringe
filter (0.45 m pore size). The filtrate was layered with hexane and
l
mol) and
1
(17.2 mg,
evaporated under reduced pressure leaving 4 as a yellow orange
25
l
solid. Yield: 19 mg (quantitative).
3
1H NMR (CDCl3): d 0.91, 0.94 (2ꢃ t, JHH ꢂ 7.5 Hz, 18 H, Me of
l
PBu3), 1.38–1.70 (m, 24 H, b- and c-CH2 of PBu3), 1.90–1.98 (m,
the mixture was allowed to crystallise at ꢁ18 °C for several days.
The separated crystalline product was filtered off, washed with
hexane and dried in air to afford 2ꢀ2CH2Cl2 as red crystals. Yield:
14 mg (54%).
12 H,
a
-CH2 of PBu3), 4.35 (m, 2 H, fc), 4.57 (apparent q, J ꢂ 2 Hz,
2 H, fc), 4.69, 4.79 (2ꢃ apparent t, J ꢂ 2 Hz, 2 H, fc); 5.04 (d,
3JHH = 6.2 Hz, 2 H, NHCH2), 6.85, 7.16 (2ꢃ m, 1 H, C6H4); 7.19 (t,
3JHH = 6.2 Hz, 1 H, NH), 7.32–7.70 (m, 22 H, C6H4 and PPh2).
1H NMR (CDCl3): d 4.34 (apparent t, J = 1.9 Hz, 2 H, fc), 4.54 (br s,
31P{1H} NMR (CDCl3):
d
12.0 (d, JPP = 558 Hz), 14.0 (d,
2
3
2H, fc), 4.64 (m, 2 H, fc), 4.94 (d, JHH = 4.6 Hz, 2 H, NHCH2), 5.21
2JPP = 531 Hz), 17.5 (d, 2JPP = 558 Hz), 20.3 (d, 2JPP = 531 Hz). IR (Nu-
(m, 2 H, fc), 6.82 (m, 1 H, C6H4), 7.23 (m, 1 H, C6H4), 7.32–7.75
jol): NH), 1657 (s, amide I), 1518 (s, amide II),
m
/cmꢁ1 3346 (w,
m
3
(m, 22 H, C6H4 and PPh2), 7.80 (t, JHH = 4.6 Hz, 1 H, NH). 31P{1H}
1435 (vs), 1302 (m), 1277 (m), 1166 (m), 1093 (m), 1029 (m),
999 (w), 967 (w), 903 (m), 744 (s), 693 (vs), 503 (composite s),
467 (m). ESI+ MS: m/z 1374 ([Pd2(PBu3)2Cl2(1)ꢁH]+); the observed
isotopic distribution agreed to the calculated one. Anal. Calc. for
2
NMR (CDCl3): d 12.2 and 18.2 (2ꢃ d, JPP = 572 Hz). IR (Nujol):
m
/cmꢁ1 3341 (w,
mNH), 1652 (s, amide I), 1635 (vs, amide I), 1525
(vs, amide II), 1481 (m), 1434 (vs), 1306 (m), 1277 (s), 1198 (w),

ˇ ˇ
P. Štepnicka et al. / Journal of Organometallic Chemistry 694 (2009) 2987–2993
2992
C66H89Cl4FeNOP4Pd2 (1446.7): C, 54.79; H, 6.20; N, 0.97. Found: C,
54.98; H, 6.28; N, 0.97%.
Crystallographic data: C43.25H36.25Cl5.75FeNOP2Pd (2ꢀ1.25CHCl3),
M = 1014.01 g molꢁ1
monoclinic, space group P21/n (no. 14),
,
a = 11.5783(2), b = 14.4658(2), c = 26.3293(4) Å; b = 100.3694(9)°,
4.6. Preparation of complex 5
V = 4337.9(1) Å3, Z = 4, D = 1.553 g mLꢁ1, 62 684 diffractions of
which 9893 were unique and 8578 observed according to Io > 2
r
Di-
dipalladium(II) (13.8 mg, 25
dissolved in dichloromethane (3 mL). The solution was stirred un-
der argon for 1 h and filtered (0.45 m PTFE filter). The filtrate was
l
-chlorido-bis{2-[(dimethylamino-
j
N)methyl]phenyl-
j
C1}-
(Io) criterion, Rint = 5.00%; 510 parameters, R(observed diffrac-
tions) = 3.98%, R(all data) = 4.78%, wR(all data) = 11.67%, residual
electron density: 1.56, ꢁ1.38 e Åꢁ3 (the largest electron peak and
hole are located in the space accommodating the disordered sol-
vate molecules).
l
mol) and 1 (17.2 mg, 25
lmol) were
l
layered with hexane and the mixture was crystallised by diffusion
at 4 °C. Orange microcrystalline solid that separated during several
days was filtered off, washed with hexane and dried under vacuum
to afford 5 as an orange solid. Yield: 29 mg (93%).
5. Supplementary material
4
1H NMR (CDCl3): d 2.84 (apparent t, JPH = 2.6 Hz, 12 H, NMe2),
CCDC 714155 contains 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.
4
4.07 (br s, 2 H, CH2NMe2), 4.12 (d, JPH = 1.9 Hz, 2 H, CH2NMe2),
4.36 (m, 2 H, fc), 4.41 (apparent q, J ꢂ 2 Hz, 2 H, fc), 4.75, 4.84
(2ꢃ apparent t, J ꢂ 2 Hz, 2 H, fc), 4.88 (d, 3JHH = 6.1 Hz, 2 H, NHCH2),
6.22–6.48 (m, 4 H, C6H4), 6.78–7.76 (m, 30 H, C6H4, and 2ꢃ PPh2),
3
7.78 (t, JHH = 6.1 Hz, 1 H, NH). 31P{1H} NMR (CDCl3): d 33.2, 36.1
References
(2ꢃ s, PPh2). IR (Nujol):
m mNH), 1654 (s, amide I),
/cmꢁ1 3294 (w,
1580 (w), 1525 (s, amide II), 1436 (vs), 1304 (m), 1279 (m), 1166
(m), 1096 (m), 1026 (m), 997 (w), 973 (w), 844 (m), 744 (vs),
694 (vs), 533 (s), 515 (s), 490 (m), 477 (m). ESI+MS: m/z 1168
([Pd2(LNC)2(1)ꢁH]+; the observed isotopic distribution corre-
sponded with the calculated one. Anal. Calc. for C60H59Cl2Fe-
N3OP2Pd2 (1239.6): C, 58.13; H, 4.80; N, 3.39. Found: C, 57.82; H,
4.92; N, 3.29%.
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P. Štepnicka et al. / Journal of Organometallic Chemistry 694 (2009) 2987–2993
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