Activation of C-H and C-Br bonds in cyclopalladation reactions of Schiff base ligands: Influence of the benzylidene ring substituents

Article abstract of DOI:10.1016/j.jorganchem.2007.11.051

Reaction of Pd(AcO)₂ with the Schiff base ligands 2-Br-4,5-(OCH₂O)C₆H₂C(H){double bond, long}N(Cy) (a) and 4,5-(OCH₂CH₂)C₆H₃C(H){double bond, long}N(Cy) (b) leads to the cyclometallated compounds [Pd{2-Br-4,5-(OCH₂O)C₆HC(H){double bond, long}N(Cy)-C6,N}(μ-O₂CMe)]₂ (1a) and [Pd{4,5-(OCH₂CH₂)C₆H₂C(H){double bond, long}N(Cy)-C6,N}(μ-O₂CMe)]₂ (1b), respectively, via C-H activation. Treatment of a with Pd₂(dba)₃ gave [Pd{4,5-(OCH₂O)C₆H₂C(H){double bond, long}N(Cy)-C2,N}(μ-Br)]₂ (6a), via C-Br activation. The metathesis reaction of 1a and 1b with aqueous sodium chloride gave the corresponding cyclopalladated dimers with bridging chloride ligands, 2a and 2b, respectively. Treatment of the halogen-bridged compounds with tertiary tri- and diphosphines in the appropriate molar ratio gave the mono and dinuclear compounds 3a-5a, 7a-9a and 3b-5b. The structure of compounds 3a, 4a, 5a, 8a, 2b, 3b and 5b has been determined by X-ray diffraction analysis.

Full text of DOI:10.1016/j.jorganchem.2007.11.051

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Journal of Organometallic Chemistry 693 (2008) 685–700
www.elsevier.com/locate/jorganchem
Activation of C–H and C–Br bonds in cyclopalladation reactions of
Schiff base ligands: Influence of the benzylidene ring substituents
a
a
a
a
´
´
´
´
Leticia Naya , Digna Vazquez-Garcıa , Margarita Lopez-Torres , Alberto Fernandez ,
b,
a
a,
*
*
´
´
´
´
Jose M. Vila , Nina Gomez-Blanco , Jesus J. Fernandez
a Departamento de Quı´mica Fundamental, Universidade da Corun˜a, 15071 A Corun˜a, Spain
b Departamento de Quı´mica Inorga´nica, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
Received 30 July 2007; received in revised form 27 November 2007; accepted 27 November 2007
Available online 4 December 2007
Abstract
Reaction of Pd(AcO)2 with the Schiff base ligands 2-Br-4,5-(OCH2O)C6H2C(H)@N(Cy) (a) and 4,5-(OCH2CH2)C6H3C(H)@N(Cy)
(b) leads to the cyclometallated compounds [Pd{2-Br-4,5-(OCH2O)C6HC(H)@N(Cy)-C6,N}(l-O2CMe)]2 (1a) and [Pd{4,5-
(OCH2CH2)C6H2C(H)@N(Cy)-C6,N}(l-O2CMe)]2 (1b), respectively, via C–H activation. Treatment of a with Pd2(dba)3 gave
[Pd{4,5-(OCH2O)C6H2C(H)@N(Cy)-C2,N}(l-Br)]2 (6a), via C–Br activation. The metathesis reaction of 1a and 1b with aqueous sodium
chloride gave the corresponding cyclopalladated dimers with bridging chloride ligands, 2a and 2b, respectively. Treatment of the halogen-
bridged compounds with tertiary tri- and diphosphines in the appropriate molar ratio gave the mono and dinuclear compounds 3a–5a,
7a–9a and 3b–5b. The structure of compounds 3a, 4a, 5a, 8a, 2b, 3b and 5b has been determined by X-ray diffraction analysis.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Palladium; Schiff base; C–H activation; C–Br activation; Triphosphine; Diphosphine
1. Introduction
molecular architectures of higher complexity [4] or as com-
pounds with interesting mesogenic [5] and luminescent and
electronic properties [6], as well as their potential use in
medicine and biology [7] and in catalytic and synthetic pro-
cesses [8] has contributed significantly to the popularity of
these species. The most widely used transition metal is
without any doubt palladium, and thus cyclopalladated
compounds, i.e., the palladacycles, are known for many
types of ligands.
Regioselectivity in cyclopalladation reactions has been
observed for a number of substrates; the factors that gov-
ern metallation appear to depend on many parameters,
including hybridization of the palladated carbon atom,
the type and structural characteristics of the ligand, and
the palladium source, which ultimately determines kinetic
and thermodynamic preferences for palladation. In the
present paper, we report the reactions of Pd(AcO)2 or
[Pd2(dba)3] with Schiff base ligands, where metallation via
C–H or C–Br activation may proceed at either of the two
The synthesis of cyclometallated compounds is known
to be a very useful route to the formation of transition
metal complexes bearing carbon–metal bonds and has
become a well researched field since its beginning in the
early 1960s [1], and one of the best developed areas of orga-
nometallic chemistry [2]. Moreover, as these compounds
are generally rather stable, they are relatively easy to char-
acterize. The most popular way to achieve the synthesis of
cyclometalated complexes has been through C–H activa-
tion, and therefore this reaction was, and still is, considered
as an important model for C–H activation of hydrocarbons
by transitions metals.
The numerous applications of cyclometalated com-
pounds as chiral auxiliaries [3], as building blocks for
*
Corresponding authors.
E-mail address: qideport@usc.es (J.M. Vila).
0022-328X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.11.051

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L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
ortho positions of the phenyl ring, and the reactivity of the
resulting compounds with P-donor ligands.
dihydrobenzofuran-5-carboxaldehyde, respectively, as air-
stable solids, which were fully characterized (see Section 3).
Reaction of ligand a with palladium(II) acetate in
toluene at 60 °C for 24 h gave a yellow solid identified as
[Pd{2-Br-4,5-(OCH2O)C6HC(H)@N(Cy)-C6,N}(l-O2CMe)]2
(1a), after C–H activation at the six-position (ortho to the
2. Results and discussion
2.1. Cyclopalladated dimer complexes
1
OCH2O group). The H NMR spectrum for 1a showed a
For the convenience of the reader, the compounds and
reactions are shown in Schemes 1–3. The compounds
described in this paper were characterized by elemental
analysis (C, H, N), by mass spectrometry, and by IR and
1H, 31P–{1H} and (in part) 13C–{1H} NMR spectroscopy
(data in Section 3).
singlet assigned to the H3 proton, and absence of the H6
signal upon metallation at C6. On the other hand,
treatment of ligand b with palladium(II) acetate under sim-
ilar reaction conditions afforded compound [Pd{4,5-
(OCH2CH2)C6H2C(H)@N(Cy)-C6,N}(l-O2CMe)]2 1b after
C–H activation at the six-position exclusively. Two dou-
blets assigned to the H2 and H3 protons were observed
The Schiff base ligands a and b were prepared by reac-
tion of cyclohexylamine with 2-bromopiperonal or 3,4-
1
in the H NMR spectrum, with the resonance for the H6
O
O
4
O
O
3
5
OAc
6
i
2
Br
Br
Pd
2
N
N
1a
ii
a
O
O
O
O
O
O
Ph2
P
Ph2
P
Cl
iv
iii
Br
Br
Pd
PF6
Pd
Br
PF6
Pd
P
Ph
2
N
N
P
Ph2
N
P
Ph2
4a
2a
3a
v
N
Cl
O
O
Pd
Br
P
Ph2
P
Ph2
Br
Pd
O
O
N
Cl
5a
Scheme 1. (i) Pd(AcO)2, toluene; (ii) NaCl, acetone/water; (iii) triphos (1:2), NH4PF6, acetone–water; (iv) dppm (1:2), NH4PF6, acetone/water; (v) t-dppe
(1:1), acetone/water.

L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
687
O
4
O
3
5
6
2
Br
N
a
vi
O
O
O
PPh2
P
O
O
O
Ph2
P
Br
vii
viii
PF6
Pd
PF6
PPh
Pd
Pd
N
2
N
N
P
Ph2
P
PPh2
7a
6a
8a
ix
N
O
Br
O
Pd
P
Ph2
Ph2
P
Pd
O
O
N
Br
9a
Scheme 2. (i) Pd(dba)2, toluene; (ii) triphos (1:2), NH4PF6, acetone/water; (iii) dppm (1:2), NH4PF6, acetone/water; (iv) t-dppe (1:1), acetone/water.
proton being absent. The 13C–{1H} NMR spectra were in
accordance with the proposed structures, showing a strong
downfield shift of the HC@N and C6 carbon resonances
ca. 10 and ca. 20 ppm, respectively, from those for the free
Schiff bases consequent upon cyclometallation (see Section
3) [9].
respectively), consistent with an anti geometry of the cyclo-
metallated moieties in an ‘‘open book” arrangement linked
by two acetate-bridging ligands between the palladium
atoms, as has been observed in the related dimmer com-
pounds [13].
We have reported the influence of phenyl ring substitu-
ents in the cyclometallation of related ligands as depicted in
Fig. 1. The methoxy group at the C3 carbon atom hinders
direct metallation by palladium(II) at the C2 carbon atom
and the C6 carbon is selectively metallated, whereas the less
sterically demanding methyl group allows attack at the C2
atom [14]. In the case of cyclic substituents, the metallated
carbon atom depends on their ring size: the presence of a
OCH2CH2O group impedes approach of the metal the aro-
matic C2–H bond and only allows attack at the C6 atom;
in contrast, the presence of the smaller OCH2O group
allows the isolation of a mixture of two products, derived
In the IR spectra of complexes 1a and 1b the m(C@N)
stretch appeared at lower frequency, ca. 20 cmÀ1, than in
the free imine spectra, in accordance with nitrogen coordi-
nation to metal center [10]. This was supported by the
upfield shift of the HC@N resonance in the 1H NMR spec-
tra, ca. 1.0 ppm [11]. The mas(COO) and ms(COO) values
were consistent with bridging acetato groups [12]; a singlet
1
resonance ca. 2.0 ppm in the H NMR spectra, as well as
two singlets at ca. 130 and 23 ppm in the 13C–{1H}
NMR were assigned to the equivalent methyl acetate
groups (CH3COO, CH3COO and CH3COO resonances,

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L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
O
O
4
5
6
3
2
OAc
i
Pd
2
N
N
b
1b
ii
O
O
O
Ph2
P
Ph2
P
Cl
Pd
PF6
Pd
PF6
Pd
PPh
iii
v
2
N
N
N
P
Ph2
P
Ph2
2b
iv
4b
3b
O
Cl
N
Ph2
P
Pd
P
Ph2
Pd
Cl
N
O
5b
Scheme 3. (i) Pd(AcO)2, toluene; (ii) NaCl, acetone/water; (iii) triphos (1:2), NH4PF6, acetone/water; (iv) dppm (1:2), NH4PF6, acetone/water; (v) dppm
(1:1), acetone/water.
OMe
O
O
O
Me
Pd
MeO
O
O
O
Pd
Pd
Pd
Pd
N
R
N
R
N
R
N
R
N
R
(major)
(minor)
Fig. 1. C–H activation in cyclopalladation reactions.
from activation of the two ortho-carbon atoms, with the
major isomer being that with a C2–Pd bond [15]. In the
present paper, the presence of the 2-Br group in ligand a
directs metallation by Pd(AcO)2 exclusively towards the
C6 atom; in ligand b metallation is through the ortho car-
bon to the furane ring.
The C–Br bond in ligand a could be activated by treat-
ment with tris(dibenzilideneacetone)palladium(0) in tolu-
ene at 80 °C for 24 h. The oxidative addition reaction
afforded
[Pd{4,5-(OCH2O)C6H2C(H)@N(Cy)-C2,N}(l-
Br)]2 6a; the 1H NMR spectrum showed two singlets
assigned to the H3 and H6 nuclei, and the MS-FAB

L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
689
2
2
spectrum showed, among others, a peak assigned to [(L-H)2-
Pd2Br2]+ ion (L-H = cyclometallated ligand), in agreement
with a dinuclear nature of the complex [16].
2J(PC6) = 108.5, 3a; J(PC2) = 114.9, 7a; J(PC6) = 109.5,
3b]. The crystal structure of compounds 3a and 3b have
been determined by X-ray diffraction (vide infra).
Complexes 1a and 1b react with aqueous sodium
chloride to give [Pd{2-Br-4,5-(OCH2O)C6HC(H)@N(Cy)-
C6,N}(l-Cl)]2 (2a) and [Pd{4,5-(OCH2CH2)C6H2C(H)@
N-(Cy)-C6,N}(l-Cl)]2 (2b), respectively, with exchange of
the acetate-bridging groups by chloride-bridging ligands,
which were fully characterized (see Section 3). The IR
Treatment of the halide-bridged dinuclear complexes 2a,
6a and 2b with bis(diphenylphosphino)methane (dppm) in
a 1:2 molar ratio in the presence of NH4PF6 gave
the mononuclear compounds [Pd{2-Br-4,5-(OCH2O)-
C6HC(H)@N(Cy)-C6,N}(Ph2PCH2PPh2-P,P)][PF6]
4a,
[Pd{4,5-(OCH2O)C6H2C(H)@N(Cy)-C2,N}(Ph2PCH2P-
Ph2-P,P)][PF6] 8a and [Pd{4,5-(OCH2CH2)C6H2C(H)@
N(Cy)-C6,N}(Ph2PCH2PPh2-P,P)][PF6] 4b, respectively,
as 1:1 electrolytes [18]. The MS-FAB spectra showed,
among others, the corresponding peaks assigned to [(L-
H)Pd(dppm)]+, which were characteristic clusters of isoto-
pic peaks covering about 10 m/z units, due to the presence
of the numerous palladium isotopes (see Section 3). The IR
spectrum showed the shift of the C@N stretch towards
lower wavenumbers, as compared to the free Schiff base
ligand, indicating nitrogen coordination of the C@N
group. The 31P–{1H} NMR spectra showed two doublets,
for the two non-equivalent phosphorus. The assignment
of the doublets was made on the assumption that a ligand
of greater trans influence shifts the resonance of the phos-
phorus atoms trans to it to lower frequency [19]. The 31P
chemical shifts were clearly influenced by the four-mem-
bered ring size [20], which gave a negative DR and shifted
upfield their resonance. In the 1H NMR spectra the HC@N
resonance appeared ca. d 8.40 as a doublet by coupling to
only the 31P nucleus trans to nitrogen. However, for com-
pound 8a, a doublet of doublets at d6.19 was assigned to
H3, coupled to both phosphorus nuclei; selective
decoupling experiments allowed the correct assignment of
the corresponding coupling constants [4J(Ptrans-CH3) =
9.6 Hz, 4J(Ptrans-NH3) = 7.7 Hz]. In the 13C–{1H} NMR
spectra the metallated carbon atom resonance appeared
as a doublet of doublets by coupling with the two P atoms
2J(Ptrans-CC) ca. 130 Hz, 2J(Ptrans-NC) = 4.7–8.7 Hz] and
the most of the benzylidene proton signals showed splitting
due to the 31P nuclei. The shielding effect of the phenyl
phosphine groups cis to carbon shifted to lower frequency
some proton resonances (OCH2O in 4a, H3 in 8a and
OCH2CH2 in 4b). The crystal structure of compounds 4a
and 8a have been determined by X-ray diffraction (vide
infra).
1
and H NMR spectra showed the absence of the acetate
ligands and in the IR spectra two m(Pd–Cl) bands were
assigned, consistent with an asymmetric Pd2Cl2 bridging
unit [17]. The crystal structure of compound 2b has been
determined by X-ray diffraction (vide infra).
2.2. Cyclopalladated complexes with phosphines
Treatment of the halide-bridged dinuclear complexes 2a,
6a and 2b with bis(2-diphenylphosphinoethyl)phenylphos-
phine (triphos) and ammonium hexafluorophosphate in a
1:2 molar ratio in acetone at room temperature yielded
the mononuclear complexes [Pd{2-Br-4,5-(OCH2O)C6-
HC(H)@N(Cy)-C6,N}{(Ph2P-CH2CH2)2PPh-P,P,P}][PF6]
3a,
[Pd{4-5-(OCH2O)C6H2C(H)@N(Cy)-C2,N}{(Ph2P-
CH2CH2)2PPh-P,P,P}][PF6] 7a and [Pd{4,5-(OCH2-
CH2)C6H2C(H)@N(Cy)-C6,N}{(Ph2PCH2CH2)2PPh-P,
P,P}][PF6] 3b, respectively (see Schemes 1–3). The com-
pounds could also be obtained by treatment of 1a and 1b
with triphos under similar conditions. The microanalytical
data and the MS-FAB spectra were consistent with the
empirical formula [(L-H)Pd(triphos)][PF6]. The conductiv-
ity data (125–150 XÀ1 cm2 molÀ1 in 10À3 mol dmÀ3 solu-
tions in dry acetonitrile) were consistent with 1:1
electrolytes [18].
The absence of m(COO) or m(Pd–Cl) bands in the IR
spectra confirmed absence of bridging ligands upon coordi-
nation of palladium to the three phosphorus atoms. The
shift of the m(C@N) stretching vibration to lower wave-
numbers and the upfield shift of the HC@N proton reso-
nance in the 1H NMR spectra showed the existence of
palladium–nitrogen interaction. The 31P–{1H} NMR spec-
tra showed a triplet (ca. 80 ppm, 1P, 3J(PP) ꢀ 25 Hz) and a
doublet (ca. 40 ppm, 2P), shifted to higher frequency with
respect to the free phosphine in agreement with phospho-
rus coordination to the metal center. This suggested two
mutually trans phosphorus atoms, with the third phospho-
rus nearly trans to the metallated carbon. The 31P reso-
nance of the central phosphorus nucleus appeared at
higher frequency due to the smaller trans influence of the
Treatment of the halide-bridged dinuclear complexes 2a,
6a and 2b with tertiary diphosphines in 1:1 molar ratio
gave the dinuclear compounds [{Pd[2-Br-4,5-(OCH2O)-
C6HC(H)@N(Cy)-C6,N]}2{l-Ph2PC(H)@C(H)PPh2}] 5a,
[{Pd[4,5-(OCH2O)C6H2C(H)@N(Cy)-C2,N]}2{l-Ph2PC(H)@
C(H)PPh2}] 9a and [{Pd[4,5-(OCH2CH2)C6H2C(H)@
N(Cy)-C6,N]}2(l-Ph2PCH2PPh2)] 5b, with the diphosphine
in a bridging mode. The MS-FAB spectrum showed peaks
assigned to [(L-H)2Pd2X2(diphosphine)]+, [(L-H)2Pd2X-
(diphosphine)]+ and [(L-H)2Pd2(diphosphine)]+ (X = Cl,
Br), showing a typical way of fragmentation. The 31P–
{1H} NMR spectra showed one singlet, in accordance with
equivalent phosphorus nuclei, indicating the symmetric
1
carbon atom [19]. The H NMR spectrum for compound
7a showed the resonance for the ortho proton to the Pd–
C bond as a doublet by coupling phosphorus [d 5.18,
4J(PH3) = 7.7 Hz]. This signal was strongly shifted to lower
frequency, ca. 2 ppm, due to the shielding effect of the
phosphine phenyl rings. The 13C–{1H} NMR spectra
showed a large coupling constant between the central phos-
phorus atom and the metallated carbon atom, [d, 1C,

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L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
nature of the complexes, shifted to higher frequency from
the free phosphine, in agreement with phosphorus coordi-
nation to metal center. In the 1H NMR spectra the HC@N
resonance appeared as a doublet by coupling to phospho-
rus, in agreement with a P trans to N arrangement, within
the terms of the ‘‘transphobic effect” [21]. The crystal struc-
ture of compounds 5a and 5b have been determined by
X-ray diffraction (vide infra).
C(3)
O(2)
Br(1)
C(4)
C(2)
C(14)
C(1)
C(5)
C(6)
O(1)
C(7)
2.3. X-ray diffraction analysis
N(1)
Suitable crystals of complexes 3a, 4a, 5a, 8a, 2b, 3b and
5b were obtained and their molecular structure determined.
The labeling schemes for the compounds are shown in Figs.
2–8. The crystals consist of discrete molecules, separated by
normal van der Waals distances. Crystallographic data and
selected interatomic distances and angles are listed in
Tables 1–4.
Pd(1)
P(1)
C(8)
P(3)
C(15)
P(2)
C(18)
C(16)
2.3.1. Molecular structure of complex 2b
C(17)
Suitable crystals of compound 2b were grown by slowly
evaporating a chloroform solution. The structure com-
prises a dinuclear molecule (one molecule per asymmetric
unit), and may be regarded as a dimeric structure in which
two cyclometallated moieties are linked by chlorine-bridg-
ing ligands (see Fig. 2). Both cyclometallated moieties have
very similar bond distances and angles and discussion will
be limited to only one of them.
Fig. 3. Molecular structure of the cation for [Pd{2-Br-4,5-(OCH2O)-
C6HC(H)=N(Cy)-C6,N}{(Ph2PCH2CH2)2PPh-P,P,P}][PF6] (3a), with
labelling scheme. Hydrogen atoms and phosphine phenyl rings have been
omitted for clarity.
C(14)
C(4)
C(7)
C(8)
C(3)
C(6)
C(23)
N(1)
Cl(1)
Pd(1)
C(2)
C(5)
C(4)
C(1)
N(2)
C(22)
C(1)
C(2)
Pd(2)
Pd(1)
P(3)
C(16)
C(3)
C(7)
N(1)
Cl(2)
P(2)
C(17)
C(17)
P(1)
O(1)
C(8)
C(14)
C(18)
C(29)
C(18)
C(15)
C(19)
Fig. 4. Molecular structure of the cation for [Pd{4,5-(OCH2CH2)-
C6H2C(H)=N(Cy)-C6,N}{(Ph2PCH2CH2)2PPh-P,P,P}][PF6] (3b), with
labelling scheme. Hydrogen atoms and phosphine phenyl rings have been
omitted for clarity.
C(30)
Each palladium atom is bonded to the ligand through
the imine nitrogen and the C(2) carbon atom; the coordina-
tion sphere is completed by the two bridging chlorine
Fig. 2. Molecular structure of [Pd{4,5-(OCH2CH2)C6H2C(H)=N(Cy)-
C6,N}(l-Cl)]2 (2b), with labelling scheme. Hydrogen atoms have been
omitted for clarity.

L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
691
C(14)
O(2)
C(14)
O(1)
C(4)
C(4)
O(1)
O(2)
C(3)
C(3)
C(2)
C(5)
C(1)
C(5)
P(1)
Br(1)
C(6)
Pd(1)
P(1)
P(2)
C(2)
C(15)
C(6)
Pd(1)
C(15)
C(1)
P(2)
C(7)
N(1)
C(7)
C(18)
C(8)
N(1)
C(8)
Fig.
7. Molecular
structure
of
the
cation
for
[Pd{4,5-
(OCH2O)C6H2C(H)@N(Cy)-C2,N}(Ph2PCH2PPh2-P,P)][PF6] (8a), with
labelling scheme. Hydrogen atoms have been omitted for clarity.
Fig. 5. Molecular structure of the cation for [Pd{2-Br-4,5-
(OCH2O)C6HC(H)=N(Cy)-C6,N} (Ph2PCH2PPh2-P,P)][PF6] (4a), with
labelling scheme. Hydrogen atoms have been omitted for clarity.
˚
The Pd(1)–N(1) bond length, 2.034(3) A, is accordance
˚
with the predicted single bond value of 2.011 A, based on
ligands. The sum of angles about the palladium atoms is
360.30°, with the only noteworthy deviation being the
somewhat reduced C(2)–Pd(1)–N(1) bond angle of
81.30(17). The geometry around the palladium atoms is
planar [mean deviation from the least square plane for
the sum of covalent radii for nitrogen (sp2) and palladium,
0.701 and 1.31 A, respectively [22]. The Pd(1)–C(2) bond
length of 1.999(4) A is shorter than the expected value of
2.081 A (based on the sum of the covalent radii for carbon
˚
˚
˚
2
˚
˚
(sp ) and palladium, 0.771 and 1.31 A, respectively),
plane Pd(1), N(1), C(2), Cl(1), Cl(2) of 0.0825 A].
O(1)
C(14)
O(2)
C(4)
C(3)
C(5)
C(6)
P(1)
Pd(1)
C(2)
Br(1)
C(1)
C(8)
C(15)
C(7)
N(1)
Cl(1)
Fig. 6. Molecular structure of [{Pd[2-Br-4,5-(OCH2O)C6HC(H)@N(Cy)-C6,N]}2{l-Ph2PC(H)@C(H)PPh2}] (5a), with labelling scheme. Hydrogen atoms
have been omitted for clarity.

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L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
O(1)
C(15)
C(14)
C(4)
C(5)
C(3)
C(2)
C(6)
C(1)
C(7)
P(1)
Cl(2)
N(2)
Pd(1)
C(22)
C(16)
C(31)
P(2)
Pd(2)
Cl(1)
N(1)
C(8)
C(21)
C(17)
C(20)
C(18)
C(19)
O(2)
Fig. 8. Molecular structure of [{Pd[4,5-(OCH2CH2)C6H2C(H)=N(Cy)-C6,N]}2(l-Ph2PCH2PPh2)] (5b), with labelling scheme. Hydrogen atoms have been
omitted for clarity.
Table 1
Crystal and structure refinement data for complexes 3a, 4a, 5a and 8a
3a
4a
5a Á 4CHCl3
8a Á CH3CN
Empirical formula
Formula weight
Temperature (K)
C
48H48BrF6NO2P4Pd
C39H37BrF6NO2P3Pd Á H2O
C58H56Br2Cl14N2O4P2Pd2
1775.91
293(2)
0.71073
Triclinic
C41H41F6N2O2P3Pd
907.07
293(2)
0.71073
1095.06
293(2)
0.71073
Monoclinic
P2(1)
962.93
293(2)
0.71073
Triclinic
˚
Wavelength (A)
Crystal system
Space group
Unit cell dimensions
Triclinic
ꢀ
ꢀ
ꢀ
P1
P1
P1
˚
a (A)
11.2440(4)
17.3833(6)
12.7943(5)
90
106.9070(10)
90
12.7116(6)
13.9014(7)
13.9784(7)
77.3320(10)
68.5880(10)
63.4860(10)
2
10.4369(9)
12.5983(11)
15.7689(13)
110.3010(10)
91.871(2)
113.5000(10)
1
9.5731(11)
12.3400(14)
18.203(2)
71.243(2)
82.818(2)
79.435(2)
2
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
Z
2
2hmax (°)
56.60
11824 [0.0786]
1.019
56.62
10143 [0.0250]
1.084
58.40
8519 [0.0363]
1.009
56.66
9851 [0.1025]
1.016
Independent reflections [Rint
]
S
R [F, I > 2r(I)]
wR [F2, all data]
0.0555
0.1099
0.0406
0.1402
0.0409
0.0961
0.0742
0.2291
Absolute structure parameter
À0.008(11)
consistent with those found in related complexes [17,23]
and with the five-membered cyclometallated ring having a
significant aromatic character [24].
The asymmetric nature of the Pd(l-Cl)2P moiety, dem-
onstrated by the Pd–Cl bond distances [Pd(1)–Cl(1),
Except for the cyclohexyl and the OCH2CH2 groups, the
cyclopalladated moiety is nearly planar. The mean devia-
tions from the least squares planes determined for the met-
allated phenyl ring [C(1), C(2), C(3), C(4), C(5), C(6)] and
the metallacycle [Pd(1), C(1), C(2), C(7), N(1)] are 0.0188
˚
2.3251(11);
Pd(1)–Cl(2),
2.4541(12);
Pd(2)–Cl(2),
and 0.0359 A, respectively. The angle between planes is
˚
2.3361(11); Pd(2)–Cl(1), 2.4622(12) A], results from the dif-
fering trans influence of the nitrogen and carbon atoms of
the Schiff base ligand [17,23,25].
5.7°. The Pd(l-Cl)2Pd bridging ring is not planar, but is
hinged about the Cl–Cl axis by 37.4°. This situation has
been observed in related compounds [23b,26], but contrasts

L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
693
Table 2
Crystal and structure refinement data for complexes 2b, 3b and 5b
2b
3b
5b Á 3CHCl3
Empirical formula
Formula weight
Temperature (K)
C30H34Cl2N2O2Pd2
738.29
293(2)
C49H51F6NOP4Pd
1014.19
293(2)
C58H61Cl11N2O2P2Pd2
1482.78
100(2)
0.71073
˚
Wavelength (A)
0.71073
0.71073
Crystal system
Space group
Unit cell dimensions
Monoclinic
P2(1)/n
Monoclinic
P2(1)/n
Monoclinic
P1n1
˚
a (A)
13.2638(11)
14.5938(12)
15.1758(13)
90
18.6972(8)
11.1367(5)
22.6435(10)
90
10.603(3)
15.079(4)
19.298(5)
90
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
100.327(2)
90
92.7770(10)
90
90.659(7)
90
Z
4
4
2
2hmax (°)
Independent reflections [Rint
S
56.72
7186 [0.0565]
1.028
56.66
11701 [0.1541]
0.979
50.00
10828 [0.1499]
1.001
]
R [F, I > 2r(I)]
wR [F2, all data]
Absolute structure parameter
0.0416
0.0996
0.0649
0.1693
0.0593
0.1043
À0.07(3)
Table 3
Selected bond distances (A) and angles (°) for complexes 3a and 3b
˚
and a hexafluorophosphate anion. In each structure, the
palladium atom is bonded to the adjacent ortho carbon
of the phenyl ring, C(6) in 3a and C(2) in 3b, to a nitrogen
atom, and to the three phosphorus atoms of the tridentate
phosphine ligand (see Figs. 3 and 4).
The angular structural parameter s [28] was used to
describe the geometry of the above-mentioned complexes
[29]. The s values are 0.49 and 0.37 for compounds 3a
and 3b, respectively. The geometry of complex 3a nearly
halfway between square-pyramidal (with the palladium,
metallated carbon atom and the three phosphorus atoms
in the basal plane, and the iminic nitrogen at the apical
position) and trigonal-bipyramidal (with the palladium,
nitrogen and terminal phosphorus atoms in the equato-
rial plane, and the metallated carbon atom and the cen-
tral phosphorus atom at the apical positions); in compound
3a
3b
Pd(1)–C(6)
Pd(1)–C(2)
Pd(1)–N(1)
Pd(1)–P(1)
Pd(1)–P(2)
Pd(1)–P(3)
C(1)–C(6)
C(1)–C(2)
C(1)–C(7)
N(1)–C(7)
2.047(6)
2.034(5)
2.497(5)
2.3176(14)
2.3187(13)
2.3318(14)
2.405(4)
2.3026(18)
2.2993(17)
2.3145(17)
1.404(8)
1.417(8)
1.460(9)
1.246(8)
1.465(8)
1.262(7)
C(6)–Pd(1)–P(2)
C(2)–Pd(1)–P(2)
P(1)–Pd(1)–P(3)
P(1)–Pd(1)–N(1)
P(2)–Pd(1)–N(1)
P(3)–Pd(1)–N(1)
P(1)–Pd(1)–P(2)
P(2)–Pd(1)–P(3)
C(6)–Pd(1)–N(1)
C(2)–Pd(1)–N(1)
C(6)–Pd(1)–P(1)
C(2)–Pd(1)–P(1)
C(6)–Pd(1)–P(3)
C(2)–Pd(1)–P(3)
173.15(18)
170.02(17)
147.87(5)
105.67(12)
112.48(14)
106.36(12)
84.64(5)
143.53(6)
115.43(14)
110.21(15)
100.97(14)
84.10(5)
3b palladium coordination is closer to
a square-
85.65(6)
76.1(2)
85.54(5)
pyramidal.
The Pd(1)–N(1) bond distances of 2.405(4) (3a) and
77.3(2)
˚
95.71(16)
90.52(15)
2.497(5) (3b) are longer than the values of 2.338(3) A,
90.66(15)
93.90(16)
reported recently by us in a similar complex with a triphos
˚
ligand [30b] and 2.23(2) A found in an ‘‘authentic” penta-
coordinate Pd(II) complex [31]. However, the Pd–N bond
length is shorter than the weak interactions in the range
˚
2.576(4)–2.805(5) A found in other five-coordinate com-
with the most common planar configuration of the frag-
ment [(C-N)Pd(l-Cl)2Pd(C-N)] (C-N = cyclometallated
ring) [27].
plexes of palladium with mono- and diphosphines [32].
˚
The Pd–C bond lengths of 2.047(6) and 2.034(5) A for
3a and 3b, respectively, are similar to those found in related
cyclometallated complexes [30,33] with C trans to phospho-
rus but longer than Pd–C distances found in cyclometalat-
ed complexes with carbon trans to nitrogen or chlorine,
supporting a phosphine ligand in the trans position.
The Pd–P bond lengths are similar to those found
in related Pd(II) complexes [30,34] and suggest a slightly
2.3.2. Molecular structures of complexes 3a and 3b
Suitable crystals of compounds 3a and 3b were grown
from slowly evaporating dichloromethane/n-hexane solu-
tions. The crystal structures of compounds 3a and 3b com-
prise a mononuclear cation (one ion per asymmetric unit)

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L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
Table 4
˚
Selected bond distances (A) and angles (°) for complexes 4a, 5a, 8a, 2b and 5b
4a
5a
8a
2ba
5ba
Pd(1)–C(6)
Pd(1)–C(2)
Pd(1)–N(1)
Pd(1)–P(1)
Pd(1)–P(2)
Pd(1)–Cl(1)
Pd(1)–Cl(2)
C(1)–C(6)
C(1)–C(2)
C(1)–C(7)
N(1)–C(7)
2.037(3)
2.011(3)
2.033(7)
2.082(6)
2.2476(19)
2.3651(18)
1.999(4)
2.034(3)
1.991(8)
2.101(7)
2.265(3)
2.091(3)
2.2633(9)
2.3697(9)
2.102(3)
2.2728(9)
2.3744(9)
1.432(5)
2.3251(11)
2.4541(12)
2.382(2)
1.426(5)
1.438(10)
1.396(11)
1.291(10)
1.404(6)
1.435(6)
1.280(5)
1.429(12)
1.436(12)
1.274(10)
1.465(5)
1.283(5)
1.432(5)
1.272(4)
C(6)–Pd(1)–P(2)
P(1)–Pd(1)–N(1)
C(6)–Pd(1)–Cl(1)
C(2)–Pd(1)–P(2)
C(2)–Pd(1)–Cl(2)
N(1)–Pd(1)–Cl(1)
C(2)–Pd(1)–Cl(1)
C(6)–Pd(1)–N(1)
C(2)–Pd(1)–N(1)
C(6)–Pd(1)–P(1)
C(2)–Pd(1)–P(1)
P(1)–Pd(1)–P(2)
N(1)–Pd(1)–P(2)
P(1)–Pd(1)–Cl(1)
Cl(1)–Pd(1)–Cl(2)
N(1)–Pd(1)–Cl(2)
a
168.56(10)
177.23(8)
176.34(8)
169.96(10)
177.41(19)
171.9(2)
164.9(2)
177.17(12)
172.37(10)
98.54(13)
93.36(8)
80.52(12)
96.02(10)
93.3(2)
169.8(3)
80.52(13)
82.2(3)
81.30(16)
80.9(3)
98.0(3)
100.56(10)
98.4(2)
73.50(7)
105.9(2)
71.56(3)
107.75(8)
90.23(3)
89.73(9)
83.29(4)
97.17(10)
For clarity, the table includes only the observed data for one of the cyclometallated moieties.
partial double bond between the palladium and phospho-
rus atoms [35].
phosphorus atom from the diphosphine ligand which
bridges the two metal centers (trans-dppe, 5a; dppm, 5b)
completes the metal coordination sphere.
2.3.3. Molecular structures of complexes 4a, 5a, 8a and 5b
Suitable crystals of the title compounds were grown by
slowly evaporating a chloroform (4a and 5b), chloro-
form/n-hexane (5a) and acetonitrile (8a) solutions.
The sums of angles at palladium are approximately
360°, with the distortions more noticeable in the somewhat
reduced ‘‘bite” angles C(2)/C(6)-Pd(1)-N(1) consequent
upon chelation [80.52(13), 4a; 80.52(12), 5a; 82.2(3), 8a;
80.9(3), 5b]. The requirements of the four-membered che-
late ring of the phosphine force the bond angles P(1)–
Pd(1)–P(2) to 71.56(3) and 73.50(7) for compounds 4a
and 8a, respectively.
The crystal structures of 4a and 8a comprise a mononu-
clear molecule (one molecule per asymmetric unit) and a
hexafluorophosphate anion, and for compound 8a, one
acetonitrile solvent molecule. The structure of 5a comprises
a dinuclear molecule (half molecule per asymmetric unit,
due to an inversion center at the middle point of the
CH@CH double bond of the phosphine) and two chloro-
form solvent molecules. The structure of 5b comprises a
dinuclear molecule (one molecule per asymmetric unit)
and three chloroform solvent molecules (see Figs. 5–8).
For compounds 4a and 8a the coordination sphere
around each palladium atom consists of a nitrogen atom
of the imine group, an ortho carbon atom of the phenyl
ring (C6 in 4a, C2 in 8a), and two phosphorus atoms from
a chelating dppm (see Figs. 5 and 7). For compounds 5a
and 5b (see Figs. 6 and 8), the four-coordinated palla-
dium(II) atoms are bonded to an adjacent ortho carbon
atom (C6 in 4a and 5a, C2 in 8a and 5b) and to the nitrogen
atom of the imine group of the deprotonated Schiff
base ligand and to a chlorine atom (trans to carbon). A
The geometry around the palladium atom is slightly dis-
torted square-planar, the mean deviations from the least
squares planes are 0.0900 (4a), 0.0767 (5a), 0.0212 (8a)
and 0.1801 (5b).
˚
The palladium–nitrogen bond lengths, ca. 2.1 A (see
Table 4), are longer than the single bond predicted value
˚
of 2.011 A, and reflects the trans influence of the phospho-
rus atom [23,36]. The palladium–carbon bond lengths, ca.
˚
2.0 A (see Table 4), are within the expected value of
˚
2.081 A, but longer than those found in related complexes
where partial multiple-bond character of the Pd–C bond
was proposed [37], suggesting some degree of multiple-
bond character in the Pd–C(aryl) linkage. The palla-
dium–phosphorus bond distances are shorter than the
sum of the single bond radii for palladium and phosphorus,
˚
2.41 A, suggesting some partial double bond between both

L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
695
atoms and are similar to others reported earlier [38]. In
compounds 4a and 8a, the differing influence of the phenyl
carbon and imine nitrogen atoms is clearly illustrated by
the Pd–P distance trans to carbon, Pd(1)–P(1), and trans
to nitrogen, Pd(1)–P(2), [2.263(1) versus 2.370(1), 4a;
2.248(2) versus 2.365(2), 8a; respectively]. In compounds
5a and 5b the palladium–chloro bond lengths, 2.374(1)
dry chloroform. The mixture was heated under reflux in a
Dean-Stark apparatus for 8 h. After cooling to room tem-
perature, the solvent was evaporated to give a white solid.
Yield: 98%. IR: m(C@N) 1624 h cmÀ1. NMR 1H (300 MHz,
CDCl3, d ppm, J Hz): d = 8.55 [s, 1H, Hi], 7.52 [s, 1H, H6],
6.98 [s, 1H, H3], 5.99 [s, 2H, OCH2O]. NMR 13C–{1H}
(300 MHz, CDCl3, d ppm, J Hz): d = 157.06 [s, C@N],
150.09 [s, C4], 147.73 [s, C5], 128.91 [s, C1], 116.91 [s, C2],
112.42 [s, C3], 107.84 [s, C6], 101.99 [s, OCH2O], 69.48 [s,
C7], 34.39 [s, C8/C12], 25.64 [s, C10], 24.71 [s, C9/C11].
˚
and 2.382(2) A, respectively, are consistent with Pd–Cl dis-
tances found in related species [17,38b] but longer than the
˚
sum of the covalent radii (2.30 A) as a consequence of the
trans influence of the phenyl carbon.
Except for the cyclohexyl and the OCH2O/OCH2CH2
groups, the cyclopalladated moiety is nearly planar. The
mean deviations from the least squares planes determined
for the metallated phenyl ring [C(1), C(2), C(3), C(4),
C(5), C(6); plane 1] and the metallacycle [Pd(1), C(1),
C(2)/C(6), C(7), N(1); plane 2] are 0.0089 and 0.0111
(4a), 0.0154 and 0.0837 (5a), 0.0054 and 0.0222 (8a),
3.2.2. 4,5-(OCH2CH2)C6H3C(H)@N(Cy) (b)
Schiff base ligand b was prepared similarly to give a
brown solid, but using 2,3-dihydrobenzofuran-5-carboxal-
dehyde as starting material. Yield: 98%. IR: m(C@N)
1
1638 h cmÀ1. NMR H (300 MHz, CDCl3, d ppm, J Hz):
d = 8.21 [s, 1H, Hi], 7.69 [s, 1H, H6], 7.37 [d, 1H, H2,
3J(H2H3) = 8.2], 6.77 [d, 1H, H3], 4.58 [t, 2H, CH2 ,
a
3J(HaHb) = 8.6], 3.18 [t, 2H, CH2 ]. NMR 13C–{1H}
b
˚
0.0139 and 0.0922 A (5b), respectively. The angles between
these planes are 1.1 (4a), 10.4 (5a), 2.9 (8a) and 11.7 (5b).
In compounds 4a and 8a the chelate phosphine ring
[Pd(1), P(1), P(2), C(15), plane 3] is almost planar, with a
(300 MHz, CDCl3, d ppm, J Hz): d = 162.00 [s, C4],
158.08 [s, C@N], 129.61 [s, C3], 129.58 [s, C5], 127.62 [s,
a
C1], 123.76 [s, C6], 108.86 [s, C2], 71.59 [s, CH2 ], 69.71
b
˚
mean deviation from the ideal plane of 0.1754 A (4a) and
[s, C7], 34.41 [s, C8/C12], 29.09 [s, CH2 ], 25.54 [s, C10],
0.1029° (8a). The angles between plane 3 and the previous
planes are as follows: plane 1/plane 3: 10.1 and plane
2/plane 3: 11.0, for complex 4a; and plane 1/plane 3:
12.1, plane 2/plane 3: 9.2, for complex 8a.
24.79 [s, C9/C11].
3.3. Synthesis of the cyclopalladated complexes
3.3.1. [Pd{2-Br-4,5-(OCH2O)C6HC(H)@N(Cy)-
C6,N}(l-O2CMe)]2 (1a)
3. Experimental
A
pressure tube containing 2-Br-4,5-(OCH2O)-
3.1. General remarks
C6H2C(H)@N(C6H11) (0.457 g, 1.475 mmol), palladium(II)
acetate (0.301 g, 1.341 mmol) and 20 cm3 of dry toluene
was sealed under argon. The mixture was heated for
24 h at 60 °C. After cooling to r.t. the solution was fil-
tered through celite to remove the black palladium
formed. The solvent was removed under vacuum to give
a brown oil, which was chromatographed on a column
packed with silica gel. Elution with dichloromethane/eth-
anol (0.2%) afforded the final product as a yellow solid
after solvent removal. Yield: 71%. Anal. Found: C,
40.4; H, 3.7; N, 2.8%; C32H36N2O8Br2Pd2 requires C,
40.5; H, 3.8; N, 2.9%. IR: m(C@N) 1604 h, mas(COO)
3.1.1. Safety note
Caution: Perchlorate salts of metal complexes with
organic ligands are potentially explosive. Only small
amounts of these materials should be prepared and han-
dled with great caution.
Solvents were purified by standard methods [39]. Chemi-
cals were reagent grade. The phosphines Ph2PCH2PPh2
(dppm), trans-Ph2P(CH)2PPh2 (dppe), (Ph2PCH2CH2)2-
PPh (triphos) were purchased from Aldrich-Chemie. Micro-
analyses were carried out using a Carlo Erba Elemental Ana-
lyser, Model 1108. IR spectra were recorded as Nujol mulls
or polythene discs Nujol mulls or KBr discs on a Satellite
FTIR. NMR spectra were obtained as CDCl3 solutions
and referenced to SiMe4 (1H, 13C–{1H}) or 85% H3PO4
(31P–{1H}) and were recorded on a Bruker AV-300F spec-
trometer. All chemical shifts were reported downfield from
standards. The FAB mass spectra were recorded using a
FISONS Quatro mass spectrometer with a Cs ion gun;
3-nitrobenzyl alcohol was used as the matrix.
1
1581f, ms(COO) 1427f cmÀ1. NMR H (300 MHz, CDCl3,
d ppm, J Hz): d = 7.67 [s, 1H, Hi], 6.65 [s, 1H, H3], 5.94,
5.90 [s, 2H, OCH2O], 2.02 [s, 3H, O2CMe]. NMR 13C–
{1H} (300 MHz, CDCl3, d ppm, J Hz): d = 182.10 [s,
CH3CO2], 168.63 [s, C@N], 151.03 [s, C4], 148.89 [s,
C5], 139.90 [s, C1], 128.86 [s, C6], 113.47 [s, C2], 108.31
[s, C3], 100.99 [s, OCH2O], 64.89 [s, C7], 34.61 [s, C8/
C12], 26.01 [s, C10], 25.59, 25.56 [s, C9, C11], 23.31 [s,
CH3CO2]. MS-FAB: m/z = 417.8 [{(L-H)Pd}H]+, 890.6
[(L-H)2Pd2(OAc)}H]+, 949.6 [{(L-H)2Pd2(OAc)2}H]+.
3.2. Syntheses of the ligands
3.3.2. [Pd{2-Br-4,5-(OCH2O)C6HC(H)@
N(Cy)-C6,N}(l-Cl)]2 (2a)
3.2.1. 2-Br-4,5-(OCH2O)C6H2C(H)@N(Cy) (a)
6-Bromopiperonal (1.000 g, 4.366 mmol) and cyclohex-
ylamine (1.000 g, 6.749 mmol) were added to 50 cm3 of
A solution of 1a (0.450 g, 0.474 mmol) in 15 cm3 of ace-
tone was treated with an aqueous saturated solution of

696
L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
NaCl. The pale green precipitate formed was filtered off,
washed with water and dried under vacuum. Yield 63%.
Anal. Found: C, 37.4; H, 3.4; N, 3.2%; C28H30N2O4-
Cl2Br2Pd2 requires C, 37.3; H, 3.3; N, 3.1%. IR: m(C@N)
4J(Ptrans-CC4) = 8.1, 4J(Ptrans-NC4) = 1.4], 140.17 [s, C1],
137.47 [dd, C6, 2J(Ptrans-CC6) = 128.3, 2J(Ptrans-NC6) =
4
4.7], 116.77 [d, C2, J(PC2) = 9.1], 110.62 [s, C3], 99.98 [s,
1
OCH2O], 69.14 [s, C7], 42.53 [dd, P(CH2)2P, J(Ptrans-CC)
1597f, m(Pd–Cltrans-N) 320m, m(Pd–Cltrans-C) 290m cmÀ1
.
= 28.2, 1J(Ptrans-NC) = 22.1], 33.55 [s, C8/C12], 24.97 [s,
C10], 24.60 [s, C9/C11]. P-phenyl; 133.38 [d, Co,
2J(PCo) = 13.4], 133.22 [d, Co 2J(PCo) = 13.3], 132.28 [a,
1
NMR H (300 MHz, CDCl3, d ppm, J Hz): d = 7.98 [s,
1H, Hi], 6.68 [s, 1H, H3], 5.91 [s, 2H, OCH2O]. NMR
13C–{1H} (300 MHz, CDCl3, d ppm, J Hz): d = 169.52 [s,
C@N], 150.72 [s, C4], 148.83 [s, C5], 139.58 [s, C1], 127.59
[s, C6], 113.54 [s, C2], 108.76 [s, C3], 100.81 [s, OCH2O],
66.65 [s, C7], 32.88 [s, C8/C12], 29.68 [s, C10], 25.36 [s, C9/
C11]. MS-FAB: m/z = 415.9 [(L-H)PdCl]+, 866.6 [{(L-
H)2Pd2Cl}H]+.
3
Cp], 131.80 [a, Cp], 129.79 [d, Cm, J(PCm) = 12.3], 129.13
[3J(PCm) = 10.8], 127.53 [dd, Ci, 1J(PCi) = 51.8,
3J(PCi) = 3.9],
126.85
[dd,
Ci,
1J(PCi) = 34.9,
3J(PCi) = 4.3]. MS-FAB: m/z = 799.9 [(L-H)Pd(dppm)]+.
Specific molar conductivity: Km = 150.0 XÀ1 cm2 molÀ1
(in acetonitrile).
3.3.3. [Pd{2-Br-4,5-(OCH2O)C6HC(H)@N(Cy)-
C6,N}{(Ph2PCH2CH2)2PPh-P,P,P}][PF6] (3a)
3.3.5. [{Pd[2-Br-4,5-(OCH2O)C6HC(H)@N(Cy)-
C6,N]}2{l-Ph2PC(H)@C(H)PPh2}] (5a)
(Ph2PCH2CH2)2PPh (0.024 g, 0.044 mmol) was added
to a suspension of 2a (0.020 g, 0.022 mmol) in acetone
(10 cm3). The mixture was stirred for 30 min, after which
an excess of ammonium hexafluorophosphate was added.
The mixture was stirred for a further 1 h, after which the
complex was precipitated out by addition of water, filtered
off and dried in vacuo, gave the final compound as a pale
yellow solid. Yield: 84%. Anal. Found: C, 52.5; H, 4.6;
N, 1.4%; C48H48NO2BrF6P4Pd requires C, 52.6; H, 4.4;
Ph2PCH2PPh2 (0.031 g, 0.078 mmol) was added to a
suspension of 2a (0.070 g, 0.078 mmol) in acetone
(15 cm3). The mixture was stirred for 24 h and solvent
removed to give a white solid which was recrystallized from
chloroform/hexane. Yield: 64%. Anal. Found: C, 49.8; H,
4.1; N, 2.1%; C54H52N2O4Cl2Br2P2Pd2 requires C, 49.9;
1
H, 4.0; N, 2.2%. IR: m(C@N) 1615m cmÀ1. NMR N H
(300 MHz, CDCl3, d ppm, J Hz): d = 8.45 [m, 1H, Hi],
6.98 [ta, 1H, CH@CH, N = 18.9], d6.52 [s, 1H, H3], 4.83
[s, 2H, OCH2O]. NMR 31P–{1H} (300 MHz, CDCl3, d
1
N, 1.3%. IR: m(C@N) 1612m cmÀ1. NMR H (300 MHz,
CDCl3, d ppm, J Hz): d = 8.54 [s, 1H, Hi], 6.59 [s, 1H,
H3], 4.53 [s, 2H, OCH2O]. NMR 31P–{1H} (300 MHz,
CDCl3, d ppm, J Hz): d = 84.45 [t, 1P, 3J(PP) = 24.0],
41.96 [d, 2P]. NMR 13C–{1H} (500 MHz, CDCl3, d ppm,
ppm,
J
Hz): d = 28.87 [s]. MS-FAB: m/z = 814.0
[(L-H)PdCl{PPh2C(H)@C(H)}]+, 989.1 [(L-H)Pd2Cl2-
(t-dppe)]+.
3
J Hz): d = 165.55 [d, C@N, J(PC@N) = 4.3], 151.62 [s,
3.3.6. [Pd{4,5-(OCH2O)C6H2C(H)@N(Cy)-C2,N}(l-
Br)]2 (6a)
C4], 146.80 [d, C5, 3J(PC5) = 7.0], 140.35 [d, C6,
3
2J(PC6) = 108.5], 135.00 [d, C1, J(PC1) = 2.7], 119.14 [d,
A pressure tube containing 4,5-(OCH2CH2)C6H3-
C2, 4J(PC2) = 10.2], 109.23 [s, C3], 99.64 [s, OCH2O],
66.80 [s, C7], 32.92 [s, C8/C12], 31.55, 25.69 [m,
P(CH2)2P], 25.39 [s, C10], 25.10 [s, C9/C11]. P-phenyl;
133.03 [ta, Ci], 132.81 [ta, Co], 131.99 [ta, Co], 131.73 [s,
Cp], 131.33 [ta, Co], 131.71 [s, Cp], 131.01 [ta, Ci], 130.45
[s, Cp], 129.54 [ta, Ci], 129.50 [d, Cm], 128.79 [ta, Cm],
128.13 [ta, Cm]. MS-FAB: m/z = 737.0 [(L-H-Br)Pd(tri-
phos)]+, 950.1 [{(L-H)Pd(triphos)}H]+. Specific molar con-
ductivity: Km = 122.9 XÀ1 cm2 molÀ1 (in acetonitrile).
C(H)@N(C6H11) (0.297 g, 0.958 mmol), tris- (dibenzyli-
deneacetone)dipalladium(0) (0.399 g, 0.436 mmol) and
50 cm3 of dry toluene was sealed under argon. The mixture
was heated for 24 h at 80 °C. After cooling to r.t. the sol-
vent was removed under vacuum to give a green solid.
Yield: 71%. Anal. Found: C, 40.3; H, 3.7; N, 3.3%;
C28H32N2O4Br2Pd2 requires C, 40.4; H, 3.9; N, 3.4%. IR:
m(C@N) 1613d cmÀ1. NMR 1H (300 MHz, CDCl3, d
ppm, J Hz): d = 8.05 [s, 1H, Hi], 7.40 [s, 1H, H6], 6.99 [s,
1H, H3], 5.94 [s, 2H, OCH2O]. MS-FAB: m/z = 752.9
[(L-H)2Pd2Br]+, 832.8 [(L-H)2Pd2Br2]+.
3.3.4. [Pd{2-Br-4,5-(OCH2O)C6HC(H)@N(Cy)-
C6,N}(Ph2PCH2PPh2-P,P)][PF6] (4a)
Compounds 4a was obtained as pale brown, following a
similar procedure that 3a but using the phosphine
Ph2PCH2PPh2.
3.3.7. [Pd{4-5-(OCH2O)C6H2C(H)@N(C6H11)-
C2,N}{(Ph2PCH2CH2)2PPh-P,P,P}][PF6] (7a)
Compound 7a was obtained as a yellow solid, following
a similar procedure that 3a but using 6a and as starting
material.
Yield: 89%. Anal. Found: C, 56.8; H, 4.8; N, 1.3%;
C48H49NO2P4F6Pd requires C, 56.7; H, 4.9; N, 1.4%. IR:
m(C@N) 1596d cmÀ1. NMR 1H (300 MHz, CDCl3, d
ppm, J Hz): d = 7.94 [s, 1H, Hi], 6.82 [d, 1H, H6], 5.70 [s,
2H, OCH2O], 5.18 [d, 1H, H3, 4J(PH3) = 7.7]. NMR
31P–{1H} (300 MHz, CDCl3, d ppm, J Hz): d = 85.45 [d,
2P, 3J(PP) = 26.3], 43.7 [t, 1P]. NMR 13C–{1H}
Yield: 81%. Anal. Found: C, 49.7; H, 3.9; N, 1.4%;
C39H37NO2BrF6P3Pd requires C, 49.6; H, 3.9; N, 1.5%
1
IR: m(C@N) 1604hd cmÀ1. NMR H (300 MHz, CDCl3,
4
d ppm, J Hz): d = 8.53 [d, 1H, Hi, J(Ptrans-NHi) = 6.4],
6.71 [s, 1H, H3], 5.06 [s, 2H, OCH2O], 4.29 [tancho, 2H,
PCH2P]. NMR 31P–{1H} (300 MHz, CDCl3, d ppm, J
Hz): d = À13.97 [d, Ptrans-N
,
2J(PP) = 72.2], À35.23 [d,
P
trans-C]. NMR 13C–{1H} (500 MHz, CDCl3, d ppm, J
Hz): d = 175.17 [s, C@N], 150.33 [s, C5], 150.15 [dd, C4,

L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
697
(500 MHz, CDCl3, d ppm, J Hz): d = 165.12 [d, C@N,
5.88 [m, H, H3], 5.68 [s, 2H,OCH2O]. NMR 31P–{1H}
(300 MHz, CDCl3, d ppm, J Hz): d = 35.80 [s]. MS-FAB:
m/z = 736.1 [{(L-H)PdBr(PPh2(CH2)2PPh)}H]+, 812.0
2
3J(PC@N) = 5.1], 158.98 [d, C2, J(PC2) = 114.9], 147.99
[d, C4, 4J(PC4) = 11.7], 145.8 [s, C5], 136.58 [d, C1,
3J(PC1) = 4.7], 117.54 [s, C3], 110.40 [d, C6,
4J(PC6) = 7.5], 100.39 [s, OCH2O], 66.75 [s, C7], 33.68 [s,
C8/C12], 33.23, 26.85 [m, P(CH2)2P], 25.10 [s, C10], 24.86
[s, C9/C11]. P-phenyl; 132.87 [ta, Co], 132.12 [ta, Co],
131.56 [d, Cp], 131.50 [ta, Ci], 131.16 [s, Cp], 131.12 [d,
Co], 130.97 [ta, Ci], 130.71 [s, Cp], 129.85 [ta, Ci], 129.63
[d, Cm], 128.73 [m, Cm]. MS-FAB: m/z = 426.0
[(L-H)Pd(P(CH2)2P)]+, 870.1 [(L-H)Pd(triphos)]+, 1015.1
[(L-H)Pd(triphos)(PF6)]+. Specific molar conductivity:
Km = 112.7 XÀ1 cm2 molÀ1 (in acetonitrile).
[(L-H)PdBr(t-dppe)]+,
918.9
[(L-H)Pd2Br(t-dppe)]+,
1151.0 [(L-H)2Pd2Br2(PPh2(CH2)2PPh)]+, 1229.0 [{(L-
H)2Pd2Br2(t-dppe)}H]+.
3.3.10. [Pd{4,5-(OCH2CH2)C6H2C(H)@N(Cy)-
C6,N}(l-O2CMe)]2 (1b)
Compound 1b was obtained as
a yellow solid,
following a similar procedure that 1a but using b as starting
material.
Yield: 56%. Anal. Found: C, 40.4; H, 3.7; N, 2.8%;
C34H44N2O6Pd2 requires C, 51.7; H, 5.6; N, 3.5%. IR:
3.3.8. [Pd{4,5-(OCH2O)C6H2C(H)@N(Cy)-
C2,N}(Ph2PCH2PPh2-P,P)][PF6] (8a)
Compound 8a was obtained as a yellow solid, following
a similar procedure that 3a but using 6a and Ph2PCH2PPh2
as starting materials.
m(C@N) 1610h, mas(COO) 1571f, ms(COO) 1412f cmÀ1
.
NMR 1H (300 MHz, CDCl3, d ppm, J Hz): d = 7.21
[s, 1H, Hi], 6.93 [d, 1H, H2, 3J(H2H3) = 7.9], 6.44 [d,
a
1H, H3], 4.58, 4.44 [m, 2H, CH2 ], 3.46, 2.96 [m, 2H,
CH2 ], 2.11 [s, 3H, O2CMe]. NMR 13C–{1H}
b
Yield: 89%. Anal. Found: C, 64.8; H, 5.4; N, 1.8%;
C39H38NO2P2Pd requires C, 64.9; H, 5.3; N, 1.9% IR:
m(C@N) 1616hd cmÀ1. NMR 1H (300 MHz, CDCl3, d
ppm, J Hz): d = 8.07 [d, 1H, Hi, 4J(Ptrans-NHi) = 7.7],
6.94 [d, 1H, H6, 5J(Ptrans-CH6) = 2.9], 6.19 [dd, 1H, H3,
4J(Ptrans-CH3) = 9.6, 4J(Ptrans-NH3) = 7.0] 5.86 [s, 2H,
OCH2O], 4.27 [dd, 2H, PCH2P, 2J(Ptrans-CH) = 8.1,
2J(Ptrans-NH) = 11.5]. NMR 31P–{1H} (300 MHz, CDCl3,
(300 MHz, CDCl3, d ppm, J Hz): d = 180.64 [s,
CH3CO2], 167.01 [s, C@N], 160.27 [s, C4], 150.25 [s,
C6], 140.51 [s, C1], 131.70 [s, C5], 127.58 [s, C3],
a
104.95 [s, C2], 71.81 [s, CH2 ], 64.33 [s, C7], 34.65,
b
30.57 [s, C8,C12], 29.93 [s, CH2 ], 26.15, 25.70, 25.52
[s, C9, C10, C11], 23.52 [s, CH3CO2].
3.3.11. [Pd{4,5-(OCH2CH2)C6H2C(H)@N(Cy)-
C6,N}(l-Cl)]2 (2b)
Compound 2b was prepared similarly that 2a as yellow
solid, but using 1b as starting material.
Yield 84%. Anal. Found: C, 48.7; H, 4.8; N, 3.7%;
C30H36N2O2 Cl2Pd2 requires C, 48.7; H, 4.9; N, 3.8%.
d ppm, J Hz): d = À6.16 [d, Ptrans-N
,
2J(PP) = 65.6],
À29.19 [d, Ptrans-C]. NMR 13C–{1H} (300 MHz, CDCl3, d
ppm, J Hz): d = 174.74 [t, C@N, 3J(PC@N) = 4.8],
157.84 [dd, C2, 2J(Ptrans-CC2) = 130.1, 2J(Ptrans-NC2) =
4
4
8.7], 149.19 [dd, C4, J(Ptrans-CC4) = 14.7, J(Ptrans-NC4) =
9.8], 145.89 [d, C5, 5J(Ptrans-CC5) = 1.4], 140.95 [d, C1,
3J(PC1) = 2.0], 117.09 [dd, C3, 3J(Ptrans-CC3) = 14.2,
IR: m(C@N) 1612f, m(Pd–Cltrans-N) 325m, m(Pd–Cltrans-C
)
1
290m cmÀ1. NMR H (300 MHz, CDCl3, d ppm, J Hz):
4
3J(Ptrans-NC3) = 4.7], 109.31 [d, C6, J(PC6) = 2.0], 101.14
d = 7.70 [s, 1H, Hi], 7.03 [d, 1H, H2, 3J(H2H3) = 7.9],
1
a 3
[s, OCH2O], 69.05 [s, C7], 41.59 [dd, P(CH2)2P, J(Ptrans-
6.49 [d, 1H, H3], 4.51 [t, 2H, CH2 , J(HaHb) = 8.8], 3.46
1
b
CC) = 27.2, J(Ptrans-NC) = 21.0], 33.27 [s, C8/C12], 24.85
[m, 2H, CH2 ]. NMR 13C–{1H} (300 MHz, CDCl3, d
[s, C10], 24.47 [s, C9/C11]. P-phenyl; 133.72 [d, Co,
2J(PCo) = 13.5], 133.35 [d, Co, 2J(Ptrans-NCo) = 13.2],
132.79 [d, Cp, 4J(PCp) = 2.9], 132.13 [d, Cp,
ppm, J Hz): d = 169.85 [s, C@N], 160.65 [s, C4], 148.98
[s, C6], 140.44 [s, C1], 133.74 [s, C5], 128.44 [s, C3], 105.91
a
[s, C2], 71.75 [s, CH2 ], 65.39 [s, C7], 33.19 [s, C8/C12],
3
b
4J(PCp) = 2.5], 129.78 [d, Cm, J(PCm) = 12.0], 129.63 [d,
29.68 [s, CH2 ], 25.58 [s, C9/C10/C11], 23.52 [s, CH3CO2].
Cm, 3J(PCm) = 10.6], 127.59 [dd, Ci, 1J(PCi) = 48.8,
3J(PCi) = 4.6]. 124.86 [dd, Ci, 1J(PCi) = 48.8, 3J(Ptrans-N
Ci) = 4.7]. MS-FAB: m/z = 720.1 [(L-H)Pd(dppm)]+. Spe-
cific molar conductivity: Km = 118.9 XÀ1 cm2 molÀ1 (in
acetonitrile).
MS-FAB:
m/z = 334.0
[(L-H)Pd]+,
705.1
[{(L-
H)2Pd2Cl}H]+.
3.3.12. [Pd{4,5-(OCH2CH2)C6H2C(H)@N(Cy)-
C6,N}{(Ph2PCH2CH2)2PPh-P,P,P}][PF6]
(3b)
3.3.9. [{Pd[4,5-(OCH2O)C6H2C(H)@N(Cy)-
C2,N]}2{l-Ph2PC(H)@C(H)PPh2}] (9a)
Compound 3b was obtained as a yellow solid, following
a similar procedure that 3a but using 2b as starting
material.
To a suspension of 6a (0.041 g, 0.048 mmol) in acetone
(15 cm3), t-Ph2P(CH2)2PPh2 (0.019 g, 0.048 mmol) was
added. The mixture was stirred for 24 h and the resulting
grey solid filtered off and dried in vacuo. Yield: 91%. Anal.
Found: C, 52.6; H, 4.2; N, 2.1%; C54H54N2O4Br2P2Pd2
requires C, 52.7; H, 4.4; N, 2.3%. IR: m(C@N) 1582f
cmÀ1. NMR 1H (300 MHz, CDCl3, d ppm, J Hz):
d = 6.77 [s, 1H, H6], 6.65 [ta, 1H, CH@CH, N = 21.4],
Yield: 80%. Anal. Found: C, 58.1; H, 5.1; N, 1.3%;
C49H51NOP4F6Pd requires C, 58.0; H, 5.1; N, 1.4%. IR:
m(C@N) 1617m cmÀ1. NMR 1H (300 MHz, CDCl3, d
ppm, J Hz): d = 8.24 [s, 1H, Hi], 7.06 [d, 1H, H2,
a
3J(H2H3) = 7.9], 6.41 [d, 1H, H3], 3.33 [t, 2H, CH2 ,
b
3J(HaHb) = 8.6], 2.99 [m, 2H, CH2 ]. NMR 31P–{1H}
(300 MHz, CDCl3, d ppm, J Hz): d = 79.51 [t, 1P,

698
L. Naya et al. / Journal of Organometallic Chemistry 693 (2008) 685–700
b
3J(PP) = 25.8], 37.90 [d, 2P]. NMR 13C–{1H} (500 MHz,
2.96 [m, 2H, CH2 ]. NMR 31P–{1H} (300 MHz, CDCl3, d
ppm, J Hz): d = 26.76 [s]. MS-FAB: m/z = 718.2 [{(L-
H)Pd(dppm)}H]+, 1089.1 [{(L-H)2Pd2Cl(dppm)}H]+.
CDCl3,
d
ppm,
J
Hz): d = 166.12 [d, C@N,
2
3J(PC@N) = 3.9], 162.82 [d, C6, J(PC6) = 109.5], 161.00
[d, C4, 4J(PC4) = 8.2], 138.16 [d, C1, 3J(PC1) = 3.5],
136.95 [d, C5, 3J(PC5) = 2.6], 133.75 [d, C3,
3.4. X-ray crystallographic study
5J(PC3) = 7.8], 105.01 [s, C2], 71.09 [s, CH2 ], 65.12 [s,
a
C7], 33.71 [s, C8/C12], 31.49, 25.51 [m, P(CH2)2P], 29.69
[s, CH2 ], 25.64 [s, C10], 25.35 [s, C9/C11]. P-phenyl;
Three-dimensional, room temperature X-ray data were
collected on Bruker Smart 1k and AXS CCD diffractome-
ters using graphite-monochromated Mo Ka radiation. All
the measured reflections were corrected for Lorentz and
polarisation effects and for absorption by semi-empirical
methods based on symmetry-equivalent and repeated
reflections. The structures were solved by direct methods
and refined by full matrix least squares on F2. Hydrogen
atoms were included in calculated positions and refined
in riding mode. In 3a the C(9)–C(13) atoms of the cyclo-
hexyl ring showed elongated thermal ellipsoids, however
attempts to treat the disorder were unsuccessful. In com-
plex 4a The O(1) atom of the water solvent molecule were
refined in two complementary positions. The F(3)–F(6)
atoms of the hexafluorophosphate ion in 3b were disor-
dered over two positions (with occupancies of approxi-
mately the 65% for the major component). The C(3s) and
Cl(8) atoms corresponding to one of the chloroform sol-
vent molecules in complex 5b were found to be disordered
over two positions (with occupancies of approximately
55% for the major component of the disorder). The refine-
ment was carried out taking into account the minor
components. Al non-hydrogen atoms were refined aniso-
tropically. The structure solution and refinement were
carried out using the program package SHELX-97 [40].
b
133.17 [ta, Ci], 133.05 [ta, Co], 132.15 [ta, Ci], 131.26 [ta,
Co], 131.25 [d, Co], 131.18 [s, Cp], 130.50 [ta, Ci], 130.45
[s, Cp], 129.37 [d, Cm], 128.83 [ta, Cm], 128.76 [ta, Cm].
MS-FAB: m/z = 862.2 [(L-H)Pd(triphos)]+. Specific
molar conductivity: Km = 130.8 XÀ1 cm2 molÀ1 (in
acetonitrile).
3.3.13. [Pd{4,5-(OCH2CH2)C6H2C(H)@N(Cy)-
C6,N}(Ph2PCH2PPh2-P,P)][PF6] (4b)
Compound 4 b was obtained as a yellow solid, following
a
similar procedure that 3a but using
2 b and
Ph2PCH2PPh2 as starting materials.
Yield: 72%. Anal. Found: C, 55.5; H, 4.8; N, 1.7%;
C40H40NOF6P3Pd requires C, 55.6; H, 4.7; N, 1.6%. IR:
m(C@N) 1613m cmÀ1. NMR 1H (300 MHz, CDCl3, d
ppm, J Hz): d = 8.09 [d, 1 H, Hi, 4J(Ptrans-NHi) = 9.0],
6.56 [d, 1H, H3 3J(H2H3) = 7.9], 4.23 [dd, 2H, PCH2P,
2J(Ptrans-NH) = 11.0, 2J(Ptrans-CH) = 8.6] 4.02 [t, 2H,
CH2 , 3J(HaHb) = 8.5], 2.18 [t, 2H, CH2 ]. NMR 31P–
{1H} (300 MHz, CDCl3, d ppm, J Hz): d = À13.84 [d,
a
b
Ptrans-N
,
2J(PP) = 73.4], À34.57 [d, Ptrans-C]. NMR 13C–
{1H} (500 MHz, CDCl3, d ppm, J Hz): d = 175.21 [t,
C@N, 3J(PC@N) = 3.9], 161.85 [dd, C4, 4J(Ptrans-CC4) =
4
2
11.7, J(Ptrans-NC4) = 3.6], 160.58 [dd, C6, J(Ptrans-CC6) =
2
132.9, J(Ptrans-NC6) = 6.2] 142.31 [s, C1], 135.62 [dd, C5,
4. Supplementary material
3J(Ptrans-CC5) = 6.7, 3J(Ptrans-NC5) = 3.9], 130.99 [d, C3,
5J(PC3) = 6.5], 107.29 [s, C2], 70.79 [CH2 ], 67.59 [d, C7,
a
CCDC 655194, 655195, 655196, 655197, 655198, 655199
and 655200 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.
1
3J(PC7) = 7.1], 43.42 [dd, P(CH2)2P, J(Ptrans-CC) = 29.2,
1J(Ptrans-NC) = 22.1], 33.17 [s, CH2 ], 33.61 [s, C8/C12],
b
25.10 [s, C10], 24.85 [s, C9/C11]. P-phenyl; 133.56 [d, Co,
2
2J(PCo) = 13.7], 133.25 [d, Co, J(PCo) = 13.2], 132.86 [d,
Cp, 4J(PCp) = 2.7], 130.99 [d, Cp, 4J(PCp) = 2.4], 129.89
[d, Cm, 3J(PCm) = 11.9], 129.80 [d, Cm, 3J(PCm) = 10.7],
Acknowledgements
1
3
127.07 [dd, Ci, J(PCi) = 46.1, J(PCi) = 5.1], 126.68 [dd,
Ci, 1J(Ptrans-NCi) = 33.4, 3J(Ptrans-NCi) = 4.5]. MS-FAB:
m/z = 718.2 [(L-H)Pd(dppm)]+. Specific molar conductiv-
ity: K m = 136.0 XÀ1 cm2 molÀ1 (in acetonitrile).
´
We thank the Ministerio de Educacion y Ciencia (Pro-
jects CTQ2006-15621-C02-02/BQU, UDC, and CTQ2006-
15621-C02-01/BQU, USC) and the Xunta de Galicia
(Ref. PGIDIT04PXI10301IF) for financial support.
3.3.14. [{Pd[4,5-(OCH2CH2)C6H2C(H)@N(Cy)-
C6,N]}2(l-Ph2PCH2PPh2)] (5b)
Compound 5b was obtained as a pale yellow solid fol-
lowing a similar procedure that 5a but using 2b and
Ph2PCH2PPh2 as starting materials.
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