Synthesis and reactivity of new functionalized Pd(II) cyclometallated complexes with boronic esters

Article abstract of DOI:10.1016/j.jorganchem.2009.07.009

Treatment of the functionalized Schiff base ligands with boronic esters 1a, 1b, 1c and 1d with palladium (II) acetate in toluene gave the polynuclear cyclometallated complexes 2a, 2b, 2c and 2d, respectively, as air-stable solids, with the ligand as a terdentate [C,N,O] moiety after deprotonation of the -OH group. Reaction of 1j with palladium (II) acetate in toluene gave the dinuclear cyclometallated complex 5j. Reaction of the cyclometallated complexes with triphenylphosphine gave the mononuclear species 3a, 3b, 3c, 3d and 6j with cleavage of the polynuclear structure. Treatment of 2c with the diphosphine Ph₂PC₅H₄FeC₅H₄PPh₂ (dppf) in 1:2 molar ratio gave the dinuclear cyclometallated complex 4c as an air-stable solid. Deprotection of the boronic ester can be easily achieved; thus, by stirring the cyclometallated complex 3a in a mixture of acetone/water, 3e is obtained in good yield. Reaction of the tetrameric complex 2a with cis-1,2-cyclopentanediol in chloroform gave complex 2c after a transesterification reaction. Under similar conditions complexes 3a and 3d behaved similarly: with cis-1,2-cyclopentanediol, pinacol or diethanolamine complexes 3c, 3b, 3g and 3f, were obtained. The pinacol derivatives 3b and 3g experiment the Petasis reaction with glyoxylic acid and morpholine in dichloromethane to give complexes 3h, and 3i, respectively.

Full text of DOI:10.1016/j.jorganchem.2009.07.009

Journal of Organometallic Chemistry 694 (2009) 3597–3607
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and reactivity of new functionalized Pd(II) cyclometallated
complexes with boronic esters
a
a
Nina Gómez-Blanco a, Jesús J. Fernández a, , Alberto Fernández , Digna Vázquez-García ,
*
Margarita López-Torres a, Antonio Rodríguez a, José M. Vila b,
a Departamento de Química Fundamental, Universidad de La Coruña, E-15071 La Coruña, Spain
*
b Departamento de Química Inorgánica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Treatment of the functionalized Schiff base ligands with boronic esters 1a, 1b, 1c and 1d with palladium
(II) acetate in toluene gave the polynuclear cyclometallated complexes 2a, 2b, 2c and 2d, respectively, as
air-stable solids, with the ligand as a terdentate [C,N,O] moiety after deprotonation of the –OH group.
Reaction of 1j with palladium (II) acetate in toluene gave the dinuclear cyclometallated complex 5j. Reac-
tion of the cyclometallated complexes with triphenylphosphine gave the mononuclear species 3a, 3b, 3c,
3d and 6j with cleavage of the polynuclear structure. Treatment of 2c with the diphosphine
Ph2PC5H4FeC5H4PPh2 (dppf) in 1:2 molar ratio gave the dinuclear cyclometallated complex 4c as an
air-stable solid.
Received 17 May 2009
Received in revised form 3 July 2009
Accepted 6 July 2009
Available online 9 July 2009
Keywords:
Cyclometallation
Schiff bases
Deprotection of the boronic ester can be easily achieved; thus, by stirring the cyclometallated complex
3a in a mixture of acetone/water, 3e is obtained in good yield. Reaction of the tetrameric complex 2a with
cis-1,2-cyclopentanediol in chloroform gave complex 2c after a transesterification reaction. Under similar
conditions complexes 3a and 3d behaved similarly: with cis-1,2-cyclopentanediol, pinacol or diethanol-
amine complexes 3c, 3b, 3g and 3f, were obtained. The pinacol derivatives 3b and 3g experiment the
Petasis reaction with glyoxylic acid and morpholine in dichloromethane to give complexes 3h, and 3i,
respectively.
Palladium
Phosphines
Boronic esters
Crystal structure
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
of aryl- and vinylboronic acids with aldehydes and amines, some-
times referred to as the boronic acid Mannich reaction, which is a
In past decades the chemistry of cyclometallated transition me-
tal complexes has attracted much attention, being the five-mem-
bered palladacycles the most widely studied [1]. Cyclometallated
complexes present applications in catalytic and synthetic pro-
cesses [2], as chiral auxiliaries [3] or as building blocks for molec-
ular architectures of higher complexity [4]. They also show
interesting mesogenic [5] and luminescent and electronic proper-
ties [6] and potential applications in medicine and biology [7].
On the other hand, boronic acids and boronic esters have found
numerous applications in organic and medicinal chemistry [8]. In
particular, boronic esters have proven to be of great importance
in asymmetric synthesis [9]; the facile introduction and recovery
of chiral auxiliaries is the key step, and transesterification is the
one of the simplest procedures by which chiral auxiliaries may
be introduced to, and recovered from, an ester. Another important
application of boronic acids is the Petasis multicomponent reaction
powerful and convenient method for the one-pot formation of
unnatural amino acid derivatives [10,11].
Although the synthesis and reactivity of boronic acids and es-
ters is well studied, few complexes in which this group is part of
a coordinated ligand are known [12–14].
With this in mind we reasoned that combining the properties of
cyclometallated complexes and of boronic acids could be of great
interest and we therefore decided to examine functionalized Schiff
bases with boronic esters as ligands in the cyclometallation reac-
tion with palladium(II). As a result herein we present the synthesis
of, to the best of our knowledge, the first functionalized cyclomet-
allated complexes with boronic acids and boronic esters. Their
reactivity towards the transesterification and the Petasis reaction
is also described.
2. Results and discussion
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) and by IR
* Corresponding authors. Fax: +34 981 167065 (J.J. Fernández), +34 981 595012
(J.M. Vila).
E-mail addresses: qiluaafl@udc.es (J.J. Fernández), josemanuel.vila@usc.es (J.M.
Vila).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.07.009

3598
N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
O
O
N
O
O
HO
OH
O
B
B
B
a R = F
b R = F
O
H
O
B
i
ii
14
O
R
R
B
13
R
O
Hi
OH
H
15
O
16
14
O
17
c R = F
d R =H
B
13
O
a- c R = F
R = H
1a-1d
iii
O
d
B
O
16
O
14
13
O
15
17
B
O
O
O
O
N
B
4
B
O
N
O
5
Pd
3
Ph
v
P2
P
F
iv
6
Fe
R
F
2
1
PPh3
R
Ph
Pd
2
Pd
Pd
Hi
O
O
12
11
N
7
8
N
O
B
O
4
910
4c
2a-2d
3a-3d
vi
HO
OH
B
PPh3
F
Pd
O
N
3e
Scheme 1. (i) 1,2-Diol, toluene, reflux; (ii) aminophenol, chloroform, reflux; (iii) Pd(OAc)2, toluene, 60 °C; (iv) PPh3, chloroform; (v) dppf, chloroform; (vi) acetone/water.
10
9
8
7
11
B
O
O
3
O
O
O
O
B
B
4
5
i
ii
6
OAc
2
PPh3
OAc
F
F
2
F
1
Pd
Pd
Hi
N
N
N
12
17
16
15
13
14
1j
5j
6j
Scheme 2. (i) Pd(OAc)2, toluene, 60 °C; (ii) PPh3, acetone.
spectroscopy and by 1H, 31P–{1H} and, in part, 13C–{1H} NMR spec-
troscopy and mass spectrometry (see Section 4).
free ligand value, due to nitrogen coordination of the imine
[15,16], and the absence of the (O–H) stretch, in accordance with
m
Reaction of ligands 1a–1d with palladium (II) acetate in toluene
at 60 °C gave the cyclometallated complexes 2a–2d, as air-stable
solids which were fully characterized. The IR spectra showed the
loss of the –OH proton. This observation was confirmed by absence
of the OH signal in the 1H NMR spectra. The HC@N and H5 reso-
nances in the 1H NMR spectra were highfield shifted, as compared
to the uncoordinated ligands, by ca. 1.5 and 0.9 ppm, respectively;
shift of the m(C@N) stretch toward lower wavenumbers, from the

N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
3599
NH
O
O
N
O
O
N
B
O
O
N
B
B
ii
R
i
PPh3
O
R
Pd
PPh3
O
F
Pd
Pd
O
4
3a R = F
3d R = H
2a R = F
2d R = H
3f
ii
ii
ii
14
13
16
15
13
14
O
17
O
O
O
O
O
B
B
B
4
3
2
5
6
i
F
PPh3
PPh3
O
F
R
Pd
1
Pd
Pd
O
N
Hi
O
12
N
N
7
8
11
910
3c
4
3b R = F
3g R = H
2c
iii
O
13
N
14
O
α
17
OH
16
PPh3
O
R
Pd
N
3h R = F
3i R = H
Scheme 3. (i) PPh3, chloroform; (ii) diol, chloroform; (iii) HCOCO2H, morpholine, dichloromethane.
the low d values were in agreement with the structure of the com-
plexes which puts the HC@N and H5 protons in the proximity of
the shielding zone of the phenyl rings of a neighbouring metallated
ligand [17–20].
Complex 2c was also characterized by 13C–{1H} NMR spectros-
copy. The most noticeable feature was the shift to higher frequency
of the C6, C@N, and C1 resonances, as compared to their value in
the spectrum of the uncoordinated ligand, confirming that metalla-
tion had occurred [17,18,20]; the smallest shift was observed for
the C@N carbon resonance of only 2.7 ppm. The resonance as-
signed to the C–O carbon was also shifted to higher frequency
(15.7 ppm) consequent upon Pd–O bond formation.
The mass-FAB spectra showed the cluster of peaks characteris-
+
tic of the tetranuclear [Pd(L-2H)]4 fragments (see Section 4); the
isotopic patterns were in good agreement with a tetrameric
formulation.
Complex 2b was insoluble in the common deuterated solvents;
however the IR and mass-FAB spectra as well as the spectroscopic
data for its derivative 3b, allowed us to propose a similar formula-
tion as for the other tetranuclear complexes.
2.1. Crystal structure of 2c
Fig. 1. Molecular structure of [Pd{2-F-4-(-OCH(CH3)3CHO–B)C6H2C(H)@N[20-
(O)C6H4]}]4 2c, with labelling scheme. Hydrogen atoms have been omitted for
clarity.
Suitable crystals were grown by slowly evaporating a chloro-
form/n-hexane solution of the complex. The molecular structure

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N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
Table 1
Crystal and structure refinement data.
2c
3c
5j
Formula
Mr
C77H65B4Cl15F4N4O12Pd4
2314.92
C38H34BCl4FNO3PPd
861.64
C40H52.50B2F2N2O9.25Pd2
981.76
T (K)
100(2)
293(2)
293(2)
Wavelength (Å)
Crystal system
Space group
Cell dimensions
a (Å)
0.71073
Orthorhombic
Pccn
0.71073
Monoclinic
P21/c
0.71073
Trigonal
ꢀ
R3
13.912(5)
24.195(5)
26.160(5)
17.720(5)
13.219(5)
17.282(5)
25.928(1)
25.928(1)
39.404(1)
b (Å)
c (Å)
a
(°)
b (°)
113.102(5)
c
(°)
V (Å3)
8805(4)
3724(2)
22940.5(7)
Z
l
4
4
18
0.759
(mmꢁ1
)
1.746
0.872
Crystal size (mm)
2hmax (°)
0.25 ꢂ 0.20 ꢂ 0.12
0.50 ꢂ 0.18 ꢂ 0.04
0.15 ꢂ 0.12 ꢂ 0.04
56.6
56.6
50.1
Reflections:
Collected
83 395
33 796
70 897
Unique
Transmissions
10 937 (Rint = 0.028)
0.86, 0.72
0.0362
9049 (Rint = 0.064)
0.96, 0.67
0.0806
8911 (Rint = 0.099)
0.95, 0.88
0.0486
R [F, I > 2r(I)]
wR [F2, all data]
0.1336
0.2204
0.1769
Table 2
Selected bond distances (Å) and angles (°) for complexes 2c and 3c.
2c
3c
2c
3c
Pd(1)–C(1)
Pd(1)–N(1)
Pd(1)–O(1)
Pd(1)–O(2)
B(1)–O(3)
B(1)–O(4)
B(1)–C(3)
Pd(2)–C(19)
Pd(2)–N(2)
Pd(2)–O(1)
Pd(2)–O(20)
B(2)–O(5)
B(2)–O(6)
B(2)–C(21)
Pd(1)–P(1)
C(9)–O(1)
C(27)–O(2)
C(13)–O(1)
1.968(3)
1.963(3)
2.131(2)
2.059(2)
1.357(5)
1.363(5)
1.555(5)
1.965(3)
1.959(3)
2.030(2)
2.156(2)
1.358(5)
1.365(5)
1.574(5)
2.017(6)
2.021(6)
2.094(5)
C(1)–Pd(1)–N(1)
C(1)–Pd(1)–O(2)
N(1)–Pd(1)–O(1)
O(2)–Pd(1)–O(1)
C(1)–Pd(1)–P(1)
O(1)–Pd(1)–P(1)
C(19)–Pd(2)–N(2)
C(19)–Pd(2)–O(1)
N(2)–Pd(2)–O(20)
O(1)–Pd(2)–O(20)
Pd(2)–O(1)–Pd(1)
Pd(1)–O(2)–Pd(20)
82.8(1)
98.1(1)
81.1(1)
98.0(1)
82.8(1)
82.8(1)
83.11(1)
95.7(1)
81.4(1)
99.8(1)
113.4(1)
118.0(1)
81.7(2)
81.0(2)
1.367(9)
1.374(10)
1.553(11)
97.2(2)
100.1(1)
2.268(2)
1.351(4)
1.349(4)
1.325(9)
Symmetry transformations used to generate equivalent atoms: ꢁx + 3/2, ꢁy + 1/2, z.
Fig. 2. View of the crystal of 2c along the c axis.
is illustrated in Fig. 1. Crystal data are given in Table 1 and selected
bond distances and angles with estimated standard deviations are
shown in Table 2.
The asymmetric unit is formed by one half molecule of 2c and
2.5 severely disordered molecules of chloroform. The entire mole-
cule is generated by a crystallographic C2 axis which is perpendic-
ular and bisecting Pd(1)–Pd(10) and Pd(2)–Pd(20).
Each palladium is bonded in a slightly distorted square–planar
disposition to the ligand through an aryl carbon, a C@N nitrogen,
and a phenoxy oxygen atom, and to a bridging oxygen atom of a
neighbouring cyclometallated ligand monomer. Therefore, the core
of the tetrameric molecule consists of an eight-membered ring of
alternating palladium and oxygen atoms. The Pd–C [1.968(3) and
1.965(3) Å], Pd–N [1.963(3) and 1.959(3) Å] and Pd–O bond
lengths are within the expected values, with the Pd–O (trans to car-
bon) showing the larger trans influence of the carbon atom as com-
pared to nitrogen [20,19,21–23]. The B–O and B–C distances are
similar to previously reported values [12].
The Pd(1)ꢀ ꢀ ꢀPd(10) and Pd(2)ꢀ ꢀ ꢀPd(20) bond distances of 3.354(1)
and 3.357(1) Å, respectively, preclude any Pd–Pd interactions. Two
of the quasi-planar Pd-ligand units are parallel and almost orthog-
onal to the other two parallel monomer moieties, with the distance
between the parallel Pd-ligands units approximately 3.3 Å. The
crystallographic C2 axis of the tetrameric molecules is parallel to
the unit cell c axis forming channels along this direction (see
Fig. 2).
Reaction of the ligands with the unprotected –B(OH)2 group and
palladium (II) acetate were carried out under analogous reaction
conditions, however, instead of the expected cyclometallated com-
plexes, large amounts of reduced black palladium were obtained.
The use of different reaction times and temperatures and/or
change of solvent (glacial acetic acid, reflux; chloroform, room
temperature) gave similar results.

N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
3601
The crystals consist of discrete molecules separated by nor-
mal van der Waals distances. The asymmetric unit for 5j com-
prises one molecule of the complex and several molecules of
water.
The molecular configuration of complex 5j is a dimeric form
with the cyclopalladated moieties in an ‘‘open book” arrangement
linked by two acetate bridging ligands, as observed in related
dimers [27–29]. As a result, the chelating C,N bonded Schiff bases
are forced to lie above one another in the dimeric molecule. This
leads to interligand repulsions on the ‘‘open” side of the molecule
and results in the coordination planes of the palladium atoms
being tilted at an angle of 27.0°. The coordination sphere around
each cyclometallated palladium atom consists of a nitrogen atom
of the imine group, the ortho carbon of the phenyl ring, and two
oxygen atoms (one from each of the bridging acetate ligands). The
most noticeable distortion of the ideal coordination sphere corre-
sponds to the C–Pd–N bite angle of 80.7(4)° and 81.7(3)°.
The palladium–palladium distance is 2.869(1) Å and may be re-
garded as nonbonding [27–29]. The palladium–nitrogen bond
lengths [2.019(8) and 1.999(6) Å] and the palladium carbon
[1.946(9), 1.942(8) Å] bond distances are in agreement with values
previously reported for similar complexes [27–29]. The trans influ-
ence of
r-bonded carbon is clearly illustrated by the lengthening
of the palladium–oxygen distance trans to carbon (ca. 2.13 Å), rel-
ative to that trans to oxygen (ca. 2.04 Å) [28,29].
Treatment of the cyclometallated complexes 2a–2d with tri-
phenylphosphine gave the mononuclear species 3a–3d in which
the polynuclear structure has been opened due to P–Obridging bond
cleavage. The 1H NMR spectra showed the resonances due to the
H5 and HC@N protons lowfield shifted (as compared to the free li-
gands), however the HC@N shift was smaller than in the parent tet-
ranuclear complexes, in agreement with opening of the
polynuclear structure. The H5 resonance showed large shifts due
to shielding of the phosphine phenyl rings, as we have observed
before in related complexes [17,18,20]. The H5 and HC@N signals
showed the coupling to the 31P nucleus of the phosphine ligand
(3.6 and ca. 10 Hz, respectively), and in the 31P–{1H} spectra the
phosphorus resonance was a singlet ca. d 35 ppm; these findings
were in agreement with a phosphorus trans to nitrogen arrange-
ment [20,30–33].
Fig. 3. Molecular structure of [Pd{2-F-4-(-OCH(CH2)3CHO–B)C6H2C(H)@N-
[C6H11]}(CH3COO)]2 5j, with labelling scheme. Hydrogen atoms have been omitted
for clarity.
Treatment of ligand 1j with palladium (II) acetate in dry toluene
at 60 °C yielded the dinuclear cyclometallated complex 5j as an air-
stable yellow solid. The resonance corresponding to the HC@N pro-
ton appeared as a singlet at d 7.62 ppm shifted to lower frequency
consequent upon coordination of the imine group to the palladium
atom via the lone pair of the nitrogen atom [24]. The H5 resonance
also appeared as a singlet, confirming metallation of the C6 carbon.
The 1H NMR spectrum showed the signal of the acetate MeCOO
protons as a singlet at d 2.16, in agreement with the presence of
the anti isomer in the solution [25]. The IR spectrum showed the
Complexes 3b and 3c were also characterized by 13C–{1H} spec-
troscopy and their spectra were similar to those of the tetranuclear
2b and 2c complexes with the shift to higher frequency of the C6,
and C1 resonances (as compared to the uncoordinated ligand)
[17,18,20] and the lowfield shift of the C@N carbon resonance;
with the resonance assigned to the C–O carbon showing a greater
high frequency shift (ca. 22 ppm). In the mass spectra the clusters
of peaks corresponding to the molecular ions were correctly
assigned.
m
(C@N) stretch at 1614 cmꢁ1, shifted to lower wavenumbers (as
compared to the free ligand) due to N-coordination of the imine
[15,16]. The 13C–{1H} spectrum showed the characteristic lowfield
shift of the signals corresponding to the C@N, C1and C6 carbons
consequent upon metallation (vide supra and experimental). The
IR spectrum also showed strong bands assigned to the symmetric
Table 3
Selected bond lengths (Å) and angles (°) for complex 5j.
and asymmetric
m(COO) vibrations, in agreement with bridging
Pd(1)–C(1)
Pd(1)–N(1)
Pd(1)–O(5)
Pd(1)–O(7)
Pd(2)–C(21)
Pd(2)–N(2)
Pd(2)–O(6)
Pd(2)–O(8)
C(1)–Pd(1)–N(1)
N(1)–Pd(1)–O(5)
O(5)–Pd(1)–O(7)
C(1)–Pd(1)–O(7)
C(1)–Pd(1)–O(5)
N(1)–Pd(1)–O(7)
1.946(9)
2.019(8)
2.141(6)
2.033(6)
1.942(8)
1.999(6)
2.037(5)
2.135(5)
80.7(4)
97.2(3)
88.5(2)
93.6(3)
177.6(3)
173.8(3)
Pd(1)–Pd(2)
B(1)–O(1)
B(1)–O(2)
B(1)–C(3)
B(2)–O(3)
B(2)–O(4)
B(2)–C(23)
2.869(1)
1.360(13)
1.374(12)
1.557(15)
1.355(12)
1.345(12)
1.525(14)
acetate ligands [25,26]. The mass-FAB spectrum showed the clus-
ter of peaks centered at 959 amu, corresponding to the dinuclear
fragment [Pd(L-H)(OCOCH3)]2, with the expected isotopic pattern.
2.2. Crystal structure of 5j
C(21)–Pd(2)–N(2)
N(2)–Pd(2)–O(8)
O(8)–Pd(2)–O(6)
C(21)–Pd(2)–O(6)
C(21)–Pd(2)–O(8)
N(2)–Pd(2)–O(6)
81.7(3)
95.9(2)
89.4(2)
92.8(3)
173.5(3)
174.3(2)
Suitable crystals of the title compound were grown by slowly
evaporating a dichloromethane solution of the complex. The
molecular structure is illustrated in Fig. 3. Crystal data are given
in Table 1 and selected bond distances and angles with estimated
standard deviations are shown in Table 3.

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N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
2.3. Crystal structure of 3c
mononuclear compound 3c. Only one singlet (24.31 ppm) was ob-
served in the 31P–{1H} NMR spectrum for the two equivalent nuclei
in accordance with a symmetric nature of the dinuclear complex.
The mass-FAB spectrum showed the set of peaks corresponding
to the molecular ion with the isotropic patter characteristic of
the dinuclear formulation.
Suitable crystals of the title compound were grown by slowly
evaporating a dichloromethane solution of the complex. The
molecular structure is illustrated in Fig. 4. Crystal data are given
in Table 1 and selected bond distances and angles with estimated
standard deviations are shown in Table 2.
Reaction of 5j with PPh3 gave complex 6j, as an air-stable solid
which was fully characterized (see Section 4). The IR spectrum of 6j
showed strong bands at 1300 and 1555 cmꢁ1 assigned to the sym-
The crystal structure comprises one molecule of 3c and two
dichloromethane molecules per asymmetric unit. The palladium
(II) atom is bonded to the aryl carbon C(1), the imine nitrogen
N(1) and the oxygen O(1) of the Schiff base ligand and to a phos-
phorus atom of the triphenylphosphine ligand, P(1). The Pd–N(1),
2.021(6) Å, Pd–C(1), 2.017(6) and Pd(1)–P(1), 2.268(2), bond dis-
tances are within the range found earlier [17,18,20,34] The Pd–
O(1) bond distance (2.094(5) Å) reflects the trans influence of the
aryl carbon atom. The Pd–C and Pd–N bond distances are longer
than the values found in the parent complex 2c; however the
Pd–O (trans to carbon) length is somewhat shorter. The sum of an-
gles about the palladium atom is ca. 360° with the only noteworthy
deviations being the somewhat reduced N(1)–Pd(1)–C(1) and
N(1)–Pd(1)–O(1) bond angles of 82.8(1) and 81.1(1)°, respectively,
consequent upon chelation.
metric and asymmetric m(COO) vibrations, respectively, in agree-
ment with those expected for mono-coordinate acetate ligands
[26]. The 1H NMR spectrum showed the HC@N and H5 resonances
coupled to the phosphorus nucleus [d 8.33 (JPH = 9.7) and d 5.48
(JPH = 6.0 Hz), respectively], with the H5 resonance shifted towards
lower frequency due to the shielding effects of the phosphine phe-
nyl ring [17–20]. In the 31P–{1H} spectrum the resonance of the
coordinated phosphine was a singlet at d 42.04 ppm in agreement
with a phosphorus trans to nitrogen arrangement (vide supra).
2.4. Reaction at the boronic ester sites
Deprotection of the boronic ester can be easily achieved by stir-
ring the cyclometallated complex 3a in a mixture of acetone/water
from which complex 3e is recovered in good yield. The 1H NMR
spectrum of 3e showed the absence of the resonances correspond-
ing to the OCH2CH2O protons and the mass-FAB spectrum the clus-
ter of peaks, centered at 626 amu, corresponding to the molecular
ion.
An unusual characteristic of the coordinated ligand is the short-
ening of the O(4)–C(13) bond distance as compared to values re-
ported previously for uncoordinated phenols [35] [1.325(9) vs.
1.411(5) Å in N-(2-hydroxyphenyl)-2-hydroxyaniline]. This value
is also shorter than those found in complex 2c [1.351(4) and
1.349(4)].
Reaction of the cyclometallated tetramer 2c with the diphos-
phine dppf in 1:2 molar ratio gave the dinuclear cyclometallated
complex 4c, as an air-stable solid, which was fully characterized
(see Section 4). The IR and 1H NMR spectra of the complex showed
similar features for the cyclometallated moiety as those of the
Boronic esters are known to readily experiment transesterifica-
tion reactions [36] with a wide variety of diols. Similarly the reac-
tion of the tetrameric complex 2a with cis-1,2-cyclopentanediol in
chloroform gave complex 2c after column chromatography.
The cyclometallated monomers also experiment the reaction
using similar conditions; consequently, the esters of 1,2-ethane-
diol, 3a and 3d, undergo transesterification with cis-1,2-cyclopen-
tanediol, 2,3-dimethyl-2,3-butanediol (pinacol) or diethanolamine
with moderate yields, being the latter the most favourable. There-
fore, the transesterification reaction can be carried out in the cyclo-
metallated ligands using similar conditions to those used with
uncoordinated boronic esters and constitute an easy method to
functionalize cyclometallated ligands.
The pinacol derivatives 3b and 3g react with glyoxylic acid and
morpholine in dichloromethane to give complexes 3h, and 3i,
respectively. The boronic group was replaced by the amino acid,
through the formation of a C–C and a C–N bonds. This shows that
the cyclometallated aryl boronic esters can easily take part in the
multicomponent Petasis reaction. In the 1H NMR spectra of the
complexes the signals corresponding to the pinacol group disap-
peared. The resonance assigned to the Ha appeared as a singlet
at ca. 3.3 ppm and the protons of the morpholine ring as multiplets
at ca. 3.7 and 2.2 ppm. The 13C–{1H} spectra showed the signal of
the COOH carbon at ca. 172 ppm, the Ca at ca. 75 ppm and the res-
onances corresponding to the morpholine moiety at 64.6 and
51.0 ppm. The ESI-mass spectra showed the peaks corresponding
to the molecular ions at 725 and 707 amu form 3h and 3i,
respectively.
3. Conclusions
We have shown that Schiff bases bearing boronic esters may
undergo cyclometallation to give the corresponding tetranuclear,
mono- and dinuclear palladium complexes; however, it was not
possible to metallate the imines having the unprotected –B(OH)2
group. This may be due to deactivation of the phenyl ring rather
than to low stability of the resulting complexes. Thus, when the
boronic ester group on a palladacycle suffers water hydrolysis
Fig. 4. Molecular structure of [Pd{2-F-4-(-OCH(CH3)3CHO–B)C6H2C(H)@N[20-
(O)C6H4]}(PPh3)] 3c, with labelling scheme. Hydrogen atoms have been omitted
for clarity.

N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
3603
the expected product with the unprotected group is obtained in
good yield as an air-stable solid. Also, transesterification reactions
may be carried out at the boronic esters site to give new function-
alized cyclometallated palladium(II) complexes.
form. The mixture was heated under reflux in a modified Dean-
Stark apparatus for 8 h. After cooling to room temperature, the sol-
vent was evaporated to give an orange solid. Yield: 90%. IR: m(C@N)
1620 m cmꢁ1 1H NMR (300 MHz, CDCl3, d ppm, J Hz): d = 9.03 [s,
.
1H, Hi]; 8.17 [t, 1H, H6, 3J(H5H6) = 7.5, 3J(H6F) = 7.2]; 7.68 [d, 1H,
H5, 3J(H5H6) = 7.5]; 7.58 [d, 1H, H3, 3J(H3F) = 10.8]; 7.36 [dd, 1H,
H8, 3J(H8H9) = 8.0, 4J(H8H10) = 1.4]; 7.24 [td, 1H, H10,
3J(H9H10) = 3J(H10H11) = 8.0, 4J(H8H10) = 1.4]; 7.04 [dd, 1H, H11,
4. Experimental
4.1. General remarks
3J(H10H11) = 8.0,
4J(H9H11) = 1.4];
6.93
[td,
1H,
H9,
3J(H8H9) = 3J(H9H10) = 8.0, 3J(H9H11) = 1.4]; 4.43 [s, 4H, –OCH2-
CH2O–].
Solvents were purified by standard methods [37]. Chemicals
were reagent grade. Microanalyses were carried out using a Carlo
Erba Elemental Analyser, Model 1108. IR spectra were recorded
as Nujol mulls or polythene discs Nujol mulls or KBr discs on a Sa-
tellite FTIR. NMR spectra were obtained as CDCl3 solutions and ref-
erenced to SiMe4 (1H, 13C–{1H}) or 85% H3PO4 (31P–{1H}) and were
recorded on a Bruker AV-300F or AV-500F spectrometer. All chem-
ical shifts were reported downfield from standards. The FAB mass
spectra were recorded using a FISONS Quatro mass spectrometer
with a Cs ion gun using matrixes of 3-nitrobenzyl alcohol or
3-nitrophenyl octyl ether (NOPE). The ESI-mass spectra were
recorded using a QSTAR Elite mass spectrometer, using dichloro-
methane/acetonitrile or dichloromethane/ethanol as solvents.
Compound 1b was obtained as a yellow solid and compounds
1c–1d were prepared as orange solids following
a similar
procedure.
4.7. 2-F-4-(-O(CH3)2CC(CH3)2O–B)C6H3C(H)@N[20-(OH)C6H4] (1b)
(C@N) 1621sh, m cmꢁ1 1H NMR (300 MHz,
Yield: 74%. IR:
CDCl3,
m
.
d
ppm, J Hz): d = 9.02 [s, 1H, Hi]; 8.13 [t, 1H, H6,
3J(H5H6) = 7.5, 3J(H6F) = 7.2]; 7.66 [d, 1H, H5, 3J(H5H6) = 7.5];
7.57 [d, 1H, H3, 3J(H3F) = 10.8]; 7.34 [dd, 1H, H8,
3J(H8H9) = 7.8,
4J(H8H10) = 1.2];
7.25
[td,
1H,
H10,
3J(H9H10) = 3J(H10H11) = 7.8, 4J(H8H10) = 1.2]; 7.03 [dd, 1H,
H11, 3J(H10H11) = 7.8, 4J(H9H11) = 1.2]; 6.90 [td, 1H, H9,
3J(H8H9) = 3J(H9H10) = 7.8, 3J(H9H11) = 1.2]; 1.37 [s, 12H,
–OC(CH3)2C(CH3)2O–]. 13C–{1H} NMR (75.47 MHz, CDCl3, d ppm,
J Hz): d = 163.92 [s, C2]; 160.54 [s, C4]; 152.47 [s, C12], 149.79
[d, Ci, 3J(Ci,F) = 5.1]; 135.17 [s, C7]; 130.26 [d, C5,
4J(C5,F) = 3.5]; 129.37 [s, C10]; 126.62 [d, C6, 3J(C6F) = 1.7];
125.61[d, C1, 2J(C1,F) = 9.0]; 121.64 [d, C3, 2J(C3,F) = 19.4];
119.99 [s, C9]; 115.77 [s, C8]; 115.00 [s, C11]; 84.23 [s, C13,
C14], 24.70 [s, 4CH3].
4.2. Preparation of 2-F-4-(-OCH2CH2O–B)C6H3C(H)@O (a)
4-{B(OH)2}C6H3FC(H)@O (0.304 g, 1.81 mmol) and 1,2-ethane-
diol (0.112 g, 1.80 mmol) were added to 50 cm3 of toluene. The
mixture was heated under reflux for 8 h. After cooling to room
temperature, the solvent was evaporated to give a yellow pale so-
lid. Yield: 81%. IR: m(C@N) 1622sh, w, m
(HCO) 1687 s cmꢁ1. 1H NMR
(300 MHz, CDCl3, d ppm, J Hz): d = 10.40 [s, 1H, –CHO]; 7.88 [t, 1H,
H6, 3J(H5H6) = 7.6 Hz, 3J(H6F) = 6.9]; 7.67 [d, 1H, H5,
3J(H5H6) = 7.6]; 7.58 [d, 1H, H3, 3J(H3F) = 10.8]; 4.42 [s, 4H,–OCH2-
CH2O–].
Compounds b–d were obtained as yellow pales solid following
a similar procedure.
4.8. 2-F-4-(-OCH(CH2)3CHO–B)C6H3C(H)@N[20-(OH)C6H4] (1c)
Yield: 82%. IR: m .
(C@N) 1622 m cmꢁ1 1H NMR (300 MHz, CDCl3,
d ppm, J Hz): d = 9.03 [s, 1H, Hi]; 8.15 [t, 1H, H6, 3J(H5H6) = 7.5,
3J(H6F) = 7.2]; 7.65 [d, 1H, H5, 3J(H5H6) = 7.5]; 7.56 [d, 1H, H3,
3J(H3F) = 10.8]; 7.35 [dd, 1H, H8, 3J(H8H9) = 8.1, 4J(H8H10) = 1.2];
7.23 [td, 1H, H10, 3J(H9H10) = 3J(H10H11) = 8.1, 4J(H8H10) = 1.2];
7.04 [dd, 1H, H11, 3J(H10H11) = 8.1, 4J(H9H11) = 1.2]; 6.93 [td,
1H, H9, 3J(H8H9) = 3J(H9H10) = 8.1, 3J(H9H11) = 1.2]; 5.04 [br, 2H,
H13, H17]; 2.03 [m, 2H, H14, H16]; 1.69 [br, 4H, H140/H160, H15,
H150]. 13C–{1H} NMR (75.47 MHz, CDCl3, d ppm, J Hz): d = 164.10
[s, C2]; 160.72 [s, C4]; 152.67 [s, C12], 149.90 [d, Ci,
3J(Ci,F) = 5.1]; 135.32 [s, C7]; 130.57 [d, C5, 4J(C5,F) = 3.5]; 129.62
[s, C10]; 126.91 [d, C6, 3J(C6F) = 1.7]; 125.92 [d, C1,
2J(C1,F) = 9.0]; 121.93 [d, C3, 2J(C3,F) = 19.5]; 120.21 [s, C9];
115.98 [s, C8]; 115.21 [s, C11]; 83.22 [s, C13, C17]; 34.66 [s, C14,
C16]; 21.59 [s, C15].
4.3. 2-F-4-(-O(CH3)2CC(CH3)2O–B)C6H3C(H)@O (b)
Yield: 82%. IR: m(C@N) 1626sh, w, m
(HCO) 1697 s cmꢁ1. 1H NMR
(300 MHz, CDCl3, d ppm, J Hz): d = 10.41 [s, 1H, –CHO]; 7.85 [t, 1H,
H6, 3J(H5H6) = 7.5, 3J(H6F) = 6.9]; 7.68 [d, 1H, H5, 3J(H5H6) = 7.5];
7.58 [d, 1H, H3, 3J(H3F) = 10.8]; 1.37 [s, 12H, –OC(CH3)2C-
(CH3)2O–].
4.4. 2-F-4-(-OCH(CH2)3CHO–B)C6H3C(H)@O (c)
Yield: 73%. IR: m(C@N) 1620sh, m, m
(HCO) 1695 s cmꢁ1. 1H NMR
(300 MHz, CDCl3, d ppm, J Hz): d = 10.39 [s, 1H, –CHO]; 7.84 [t, 1H,
H6, 3J(H5H6) = 7.5, 3J(H6F) = 6.9]; 7.65 [d, 1H, H5, 3J(H5H6) = 7.5];
7.56 [d, 1H, H3, 3J(H3F) = 10.8]; 5.03 [s, 2H, H7, H11]; 2.03 [m,
2H, H8, H10]; 1.65 [s, 4H, H80/H100, H9, H90].
4.9. 4-(-OCH2CH2O–B)C6H4C(H)@N[20-(OH)C6H4] (1d)
Yield: 82%. IR: m .
(C@N) 1622 m cmꢁ1 1H NMR (300 MHz, CDCl3,
4.5. 4-(-OCH2CH2O–B)C6H4C(H)@O (d)
d ppm, J Hz): d = 8.72 [s, 1H, Hi]; 7.94 [s, 4H, H2, H3, H5, H6]; 7.33
[dd, 1H, H8, 3J(H8H9) = 8.1, 4J(H8H10) = 1.4]; 7.22 [td, 1H, H10,
3J(H9H10) = 3J(H10H11) = 8.1, 4J(H8H10) = 1.4]; 7.04 [dd, 1H, H11,
Yield: 43%. IR:
(300 MHz, CDCl3, d ppm, J Hz): d = 10.05 [s, 1H, –CHO]; 7.98 [d, 2H,
H2/H6 H3/
H3/H5,3J(H2H3) = 8.1]; 7.87 [d, 2H, H2/H6
H5,3J(H2H3) = 8.1]; 4.41 [s, 4H,–OCH2CH2O–].
m(C@N) 1679sh, m, m
(HCO) 1698 s cmꢁ1. 1H NMR
3J(H10H11) = 8.1,
4J(H9H11) = 1.4];
6.92
[td,
1H,
H9,
3J(H8H9) = 3J(H9H10) = 8.1, 3J(H9H11) = 1.4]; 4.43 [s, 4H, –OCH2-
ó
ó
CH2O–].
4.6. Preparation of 2-F-4-(-OCH2CH2O–B)C6H3C(H)@N[20-(OH)C6H4]
(1a)
4.10. Preparation of [Pd{2-F-4-(-OCH2CH2O–B)C6H2C(H)@N[20-(O)C6-
H4]}]4 (2a)
A pressure tube containing 4-(-OCH2CH2O–B)C6H3FC(H)@N[20-
(OH)C6H4] (0.167 g, 0.59 mmol), palladium(II) acetate (0.132 g,
4-(-OCH2CH2O–B)C6H3FC(H)@O (0.188 g, 0.97 mmol) and 2-
aminophenol (1.026 g, 0.97 mmol) were added to 50 cm3 of chloro-

3604
N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
0.59 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 red precipitate formed was filtered off and dried under vac-
uum. Yield: 69%. Anal. Calc. for C60H44N4O12F4B4Pd4: C, 46.3; H,
4.14. Preparation of [Pd{2-F-4-(-OCH2CH2O–B)C6H2C(H)@N[20-(O)C6-
H4]}(PPh3)] (3a)
PPh3 (0.099 g, 0.38 mmol) was added to a suspension of 2a
(0.147 g, 0.09 mmol) in dry chloroform (15 cm3). The mixture
was stirred for 24 h at room temperature and the solvent removed
to give a violet solid which was recrystallized form dichlorometh-
ane/hexane. Yield: 56%. Anal. Calc. for C33H28NO3PdFPB: C, 60.6; H,
2.8; N, 3.6. Found: C, 46.4; H, 2.8; N, 3.5%. IR:
m(C@N)
1590 m cmꢁ1 1H NMR (300 MHz, CDCl3, d ppm, J Hz): d = 7.57
.
[s, 1H, Hi]; 7.46 [d, 1H, H11, 3J(H10H11) = 8.1]; 6.92 [m, 2H, H3,
H10]; 6.56 [s, 1H, H5]; 6.49 [dd, 1H, H8, 3J(H8H9) = 8.1,
4J(H8H10) = 1.2]; 6.24 [td, 1H, H9, 3J(H8H9) = 3J(H9H10) = 8.1,
4.3; N, 2.1. Found: C, 60.6; H, 4.2; N, 3.4%. IR: m .
(C@N) 1575 m cmꢁ1
4J(H9H11) = 1.2]; 4.30 [s, 4H, –OCH2CH2O–]. MS-FAB: m/z = [{(L-
1H NMR (300 MHz, CDCl3, d ppm, J Hz): d = 8.20 [d, 1H, Hi,
4J(PHi) = 9.9]; 7.12 [dd, 1H, H8, 3J(H8H9) = 7.8, 4J(H8H10) = 1.5];
6.96 [td, 1H, H10, 3J(H9H10) = 3J(H10H11) = 7.8, 4J(H8H10) = 1.5];
6.88 [d, 1H, H3, 3J(H3F) = 10.2]; 6.53 [d, 1H, H11,
3J(H10H11) = 7.8]; 6.36 [t, 1H, H9, 3J(H8H9) = 3J(H9H10) = 7.8];
6.30 [d, 1H, H5, 4J(PHi) = 3.6]; 4.11 [s, 4H, –OCH2CH2O–]. 31P–
{1H} NMR (121.50 MHz, CDCl3, d ppm, J Hz): d = 34.01 [s]. MS-
FAB: m/z = [(L-H2)Pd(PPh3)]+ = 651.1.
+
H2)Pd}2H2]+ = 779.95; [{(L-H2)Pd}3H]+ = 1167.98; [(L-H2)Pd]4
=
1557.02.
Compounds 2b and 2d were obtained as red solids following a
similar procedure.
4.11. [Pd{2-F-4-(-O(CH3)2CC(CH3)2O–B)C6H2C(H)@N[20-(O)C6H4]}]4
(2b) Yield: 79%. Anal. found: C, 51.3; H, 4.4; N, 3.2;
Compounds 3b–3d were obtained as violet (3b and 3c) or gar-
net (3d) solids following a similar procedure.
C76H76N4O12B4F4Pd4 requires C, 51.2; H, 4.3; N, 3.1%. IR: m(C@N)
1573sh, m cmꢁ1. MS-FAB: m/z = [(L-H2)Pd]4+ = 1782.0.
4.15. [Pd{2-F-4-(-O(CH3)2CC(CH3)2O–B)C6H2C(H)@N[20-(O)C6H4]}(P-
Ph3)] (3b)
4.12. [Pd{4-(-OCH2CH2O–B)C6H3C(H)@N[20-(O)C6H4]}]4. (2d)
Method 1: similar procedure to that used in the synthesis of 3a.
Yield 29%.
Yield: 63%. Anal. Calc. for C60H48N4O12B4Pd4: C, 48.5; H, 3.3; N,
3.8. Found: C, 48.6; H, 3.4; N, 3.7%. IR:
(C@N) 1590 m cmꢁ1 1H
NMR (300 MHz, CDCl3, ppm, J Hz): d = 7.49 [d, 1H, H3,
Method 2: compound 3b was also prepared by treating a solu-
tion of 3a in dry chloroform (0.115 g, 0.18 mmol) with pinacol
(0.022 g, 0.18 mmol) at room temperature under argon for
10 min. The solvent was then removed under vacuum to give a res-
idue which was chromatographed on a column packed with silica
gel. Elution with ethyl acetate/hexane (1:1) followed by recrystal-
lization from dichloromethane/hexane afforded the final product
as a violet solid. Yield: 55%.
m
.
d
3J(H10H11) = 8.4]; 7.25 [d, 1H, H2, 3J(H2H3) = 8.4]; 7.12 [s, 1H,
Hi]; 6.96–6.87 [m, 2H, H10, H11]; 6.80 [s, 1H, H5]; 6.38 [dd, 1H,
H8, 3J(H8H9) = 8.1, 4J(H8H10) = 1.2]; 6.21 [t, 1H, H9,
3J(H8H9) = 3J(H9H10) = 8.1]; 4.29 [s, 4H, –OCH2CH2O–]. MS-FAB:
m/z = [(L-H2)Pd]4+ = 1485.7.
Anal. Calc. for C37H34NO3PdFBP: C, 62.8; H, 4.8; N, 1.9%. Found:
C, 62.6; H, 4.7; N, 1.8%. IR:
m .
(C@N) 1573 m cmꢁ1 1H NMR
4.13. Preparation of [Pd{2-F-4-(-OCH(CH3)3CHO–B)C6H2C(H)@N[20-
(O)C6H4]}]4 (2c)
(300 MHz, CDCl3, d ppm, J Hz): d = 8.18 [d, 1H, Hi, 4J(PHi) = 9.9];
7.11 [dd, 1H, H8, 3J(H8H9) = 7.8, 4J(H8H10) = 1.5]; 6.95 [td, 1H,
H10, 3J(H9H10) = 3J(H10H11) = 7.8, 4J(H8H10) = 1.5]; 6.88 [d, 1H,
H3, 3J(H3F) = 10.5]; 6.55 [d, 1H, H11, 3J(H10H11) = 7.8]; 6.37 [t,
1H, H9, 3J(H8H9) = 3J(H9H10) = 7.8]; 6.31 [d, 1H, H5,
4J(PH5) = 3.6]; 1.13 [s, 12H, –OC(CH3)2C(CH3)2O–]. 31P–{1H} NMR
(121.50 MHz, CDCl3, d ppm, J Hz): d = 37.77 [s]. 13C–{1H} NMR
(125.76 MHz, CDCl3, d ppm, J Hz): d = 174.24 [s, C12]; 160.15 [s,
C2]; 158.08 [s, C4]; 156.45 [s, C7]; 150.74 [s, Ci]; 143.82 [s, C1];
139.08 [dd, 3J(C5,P) = 7.3, 4J(C5,F) = 2.4]; 135.59 [s, C6]; 134.97 [d,
C-ortho, 2J(C-ortho,P) = 12.6]; 132.28 [s, C10]; 130.85 [d, C-para,
4J(C-para,P) = 2.4]; 129.45 [d, C-ipso, 1J(C-ipso,P) = 48.3]; 128.56
[d, C-meta, 3J(C-meta,P) = 10.8]; 122.14 [s, C9]; 117.22 [d, C3,
2J(C3,F) = 18.2]; 116.22 [s, C8]; 114.15 [s, C11]; 83.61 [s, C13,
C14], 24.76 [s, 4CH3]. MS-FAB: m/z = [(L-H2)Pd(PPh3)]+ = 707.1.
Method 1:
a
pressure tube containing 4-(-OCH2CH2O–
B)C6H3FC(H)@N[20-(OH)C6H4] (0.167 g, 0.59 mmol), palladium(II)
acetate (0.132 g, 0.59 mmol) and 20 cm3 of dry toluene was
sealed under argon. The mixture was heated for 24 h at 60 °C.
The solvent was removed under vacuum, and the residue ob-
tained was recrystallized from dichloromethane/hexane. The red
precipitate formed was filtered off and dried under vacuum.
Yield: 62%.
Method 2: cis-1,2-cyclopentanediol (0.027 g, 0.26 mmol) was
added to a solution of 2a (0.102 g, 0.070 mmol) in dry chloroform
under argon and stirred at room temperature for 10 min. The sol-
vent was removed under vacuum to give a red residue which
was chromatographed on a column packed with silica gel. Elution
with ethyl acetate/hexane (1:1) afforded the final product as a red
solid after solvent removal. Yield: 37%.
4.16. Preparation of [Pd{2-F-4-(-OCH(CH3)3CHO–B)C6H2C(H)@N[20-(O)-
C6H4]}(PPh3)] (3c)
Anal. Calc. for C72H60N4O12F4Pd4B4: C, 50.3; H, 3.5; N, 3.3.
Found: C, 50.4; H, 3.6; N, 3.4%. IR: m .
(C@N) 1592 m cmꢁ1 1H NMR
(300 MHz, CDCl3, d ppm, J Hz): d = 7.61 [s, 1H, Hi]; 7.44 [d, 1H,
H11, 3J(H10H11) = 8.1]; 6.91 [m, 2H, H3, H10]; 6.51 [s, 1H, H5];
6.48 [dd, 1H, H8, 3J(H8H9) = 8.1, 4J(H8H10) = 1.2]; 6.21 [td, 1H,
H9, 3J(H8H9) = 3J(H9H10) = 8.1, 4J(H9H11) = 1.2]; 4.92 [br, 2H,
H13, H17]; 1.99 [m, 2H, H14, H16]; 1.67 [br, 4H, H140/H160, H15,
Method 1: similar procedure to that used in the synthesis of 3a.
Yield 48%.
Method 2: To a solution of compound 3a in dry chloroform
(0.131 g, 0.20 mmol) cis-1,2-cyclopentanediol (0.030 g, 0.29 mmol)
was added under argon and the resulting solution stirred for
10 min. The solvent was removed to give a violet solid, which
was recrystallized from dichloromethane/hexane. Yield: 50%.
Anal. Calc. for C36H30NO3PdFPB: C, 62.5; H, 4.4; N, 2.0. Found: C,
H150]. 13C–{1H} NMR (125.76 MHz, CDCl3,
d
ppm, J Hz):
d = 168.35 [s, C12]; 159.73 [s, C2]; 157.66 [s, C4], 155.31 [s, C7];
152.62 [s, Ci]; 139.43 [d, C1, 2J(C1,F) = 6.5 Hz]; 135.93 [s, C6];
133.9 [s, C5]; 131.40 [s, C10]; 124.41 [s, C9]; 117.03 [s, C8];
115.90 [d, C3, 2J(C3,F) = 17.5]; 115.19 [s, C11]; 82.82 [s, C13,
C17]; 34.65 [s, C14, C16]; 21.69 [s, C15]. MS-FAB: m/z = [(L-
H2)Pd]4+ = 1717.9.
62.6; H, 4.3; N, 1.9%. IR: m .
(C@N) 1573 m cmꢁ1 1H NMR (300 MHz,
CDCl3, d ppm, J Hz): d = 8.19 [d, 1H, Hi, 4J(PHi) = 10.2]; 7.11 [dd, 1H,
H8, 3J(H8H9) = 8.1, 4J(H8H10) = 1.5]; 6.95 [td, 1H, H10,
3J(H9H10) = 3J(H10H11) = 8.1, 4J(H8H10) = 1.5]; 6.86 [d, 1H, H3,

N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
3605
3J(H3F) = 10.5]; 6.53 [d, 1H, H11, 3J(H10H11) = 8.1]; 6.37 [t, 1H, H9,
3J(H8H9) = 3J(H9H10) = 8.1]; 6.28 [d, 1H, H5, 4J(PHi) = 3.6]; 4.74
[br, 2H, H13, H17]; 1.86 [m, 6H, H14/H16, H140/H160, H15, H150].
31P–{1H} NMR (121.50 MHz, CDCl3, d ppm, J Hz): d = 34.02 [s].
13C–{1H} NMR (125.76 MHz, CDCl3, d ppm, J Hz): d = 174.28 [d,
C12, 3J(C12,P) = 2.8]; 160.11 [s, C2]; 158.04 [s, C4], 156.64 [s, C7];
150.69 [s, Ci]; 143.94 [s, C1]; 139.20 [dd, C5, 3J(C5,P) = 7.3,
4J(C5,F) = 2.5]; 135.59 [s, C6]; 135.00 [d, C-ortho, 2J(C-
ortho,P) = 12.7]; 132.33 [s, C10]; 130.86 [d, C-para, 4J(C-
para,P) = 2.4]; 129.95 [d, C-ipso, 1J(C-ipso,P) = 48.5]; 128.56 [d, C-
meta, 3J(C-meta,P) = 10.8]; 122.15[ s, C9]; 117.37 [d, C3,
2J(C3,F) = 18.2]; 116.22 [s, C8]; 114.18 [s, C11]; 82.56 [s, C13,
C17]; 34.56 [s, C14, C16]; 21.35 [s, C15]. MS-FAB: m/z = [(L-
H2)Pd(PPh3)]+ = 691.1.
3J(H8H9) = 8.1, 4J(H8H10) = 1.5]; 6.95 [d, 1H, H3, 3J(H3F) = 11.1];
6.86 [td, 1H, H10, 3J(H9H10) = 3J(H10H11) = 8.1, 4J(H8H10) = 1.5];
6.38 [d, 1H, H5, 4J(PHi) = 3.9]; 6.26 [t, 1H, H9, 3J(H8H9) =
3J(H9H10) = 8.1]; 6.20 [d, 1H, H11, 3J(H10H11) = 8.1]. 31P–{1H}
NMR (121.50 MHz, CDCl3, d ppm, J Hz): d = 34.69 [s]. MS-FAB:
m/z = [{(L-H2)Pd(PPh3)}H]+ = 626.07.
Compounds 4d and 1e were obtained as violet solids following a
similar procedure to the one described for the synthesis of 3c
(method 2; vide supra).
4.20. [Pd{4-(-O(CH3)2C-C(CH3)2O–B)C6H3C(H)@N[20-(O)C6H4]}(PPh3)]-
(3g)
Yield: 42%. Anal. Calc. for C37H35BNO3PdP: C, 64.4; H, 5.1; N,
2.0. Found: C, 64.3; H, 5.2; N, 1.9%. IR: m
(C@N) 1573 m. 1H NMR
4.17. [Pd{4-(-OCH2CH2O–B)C6H3C(H)@N[20-(O)C6H4]}(PPh3)] (3d)
(300 MHz, CDCl3, d ppm, J Hz): d = 7.90 [d, 1H, Hi, 4J(PHi) = 9.9];
7.23 [d; 1H, H2, 3J(H2H3) = 8.4]; 7.09–7.06 [m, 2H, H3, H8];
6.94 [ddd, 1H, H10, 3J(H9H10) = 7.1, 3J(H10H11) = 8.4,
4J(H8H10) = 1.5]; 6.57 [d, 1H, H5, 3J(PH5) = 3.9]; 6.54 [d, 1H,
H11, 3J(H10H11) = 8.4] 6.34 [t, 1H, H9, 3J(H8H9) = 3J(H9H10) =
7.1]; 1.13 [s, 12H, –OC(CH3)2C(CH3)2O–]. 13C–{1H} NMR
(125.76 MHz, CDCl3, d ppm, J Hz): d = 173.65 [d, C12, 3J(C12,P) =
3.3]; 157.21 [s, C4]; 156.25 [s, C2]; 154.50 [d, C7, 3J(C7,P) = 7.5];
143.46 [d, Ci, 3J(Ci,P) = 7.4]; 135.33 [s, C6]; 134.91 [d, C-ortho,
2J(C-ortho,P) = 12.7]; 131.96 [s, C5]; 130.92 [s, C10]; 130.67 [d,
C-para, 4J(C-para,P) = 2.3]; 130.19 [d, C-ipso, 1J(C-ipso,P) = 47.9];
128.44 [d, C-meta, 3J(C-meta,P) = 10.8]; 126.75 [s, C3]; 122.04 [s,
C9]; 115.87 [s, C8]; 113.77 [s, C11]; 83.27 [s, C13, C14], 24.69
Yield: 86%. Anal. Calc. for C33H27NO3PdBP: C, 62.5; H, 4.3; N,
2.2. Found: C, 62.6; H, 4.4; N, 2.1%. IR:
NMR (300 MHz, CDCl3, ppm, J Hz): d = 7.93 [d, 1H, Hi,
m .
(C@N) 1581 m cmꢁ1 1H
d
4J(PHi) = 9.9]; 7.24 [d, 1H, H2, 3J(H2H3) = 8.4]; 7.10 [m, 2H, H3,
H8]; 6.95 [td, 1H, H10, 3J(H9H10) = 3J(H10H111) = 8.1,
4J(H8H10) = 1.5]; 6.57–6.52 [m, 2H, H5, H11]; 6.35 [t, 1H, H9,
3J(H8H9) = 3J(H9H10) = 8.1]; 4.11 [s, 4H, –OCH2CH2O–]. 31P–{1H}
NMR (121.5 MHz, CDCl3, d ppm, J Hz): d = 34.38 [s]. MS-FAB: m/
z = [(L-H2)Pd(PPh3)]+ = 633.1.
4.18. Preparation of [Pd{2-F-4-(-OCH(CH2)3CHO–B)C6H2C(H)@N[20-
(O)C6H4]}(
l
-PPh2(
g
5-C5H4)Fe(
g
5-C5H4)PPh2)] (4c)
[s, 4CH3]; C1ocl
. d ppm,
31P–{1H} NMR (121.50 MHz, CDCl3,
J Hz): d = 34.20 [s]. MS-FAB: m/z = [(L-H2)Pd(PPh3)]+ = 689.1.
PPh2(g
5-C5H4)Fe( 5-C5H4)PPh2 (0.018 g, 0.033 mmol) was
g
added to a solution of 2a (0.028 g, 0.016 mmol) in dry chloroform
(15 cm3). The mixture was stirred for 24 h at room temperature
and the solvent removed to give a violet solid which was recrystal-
lized from chloroform/hexane. Yield: 71%. Anal. Calc. for
C70H58N2O6Pd2B2F2FeP2: C, 59.5; H, 4.1; N, 1.9. Found: C, 59.6; H,
4.21. [Pd{2-F-4-(-O(CH2)2NH(CH2)2O–B)C6H2C(H)@N[20-(O)C6H4]}(P-
Ph3)] (3f)
Yield: 70%. Anal. Calc. for C35H31N2O3PdBFP: C, 60.5; H, 4.5;
N, 4.0. Found: C, 60.4; H, 4.3; N, 4.1%. IR:
NMR (300 MHz, CDCl3, ppm, J Hz): d =8.20 [d, 1H, Hi,
m
(C@N) 1589 m. 1H
4.3; N, 2.0%. IR:
m
.
(C@N) 1575 m cmꢁ1 1H NMR (300 MHz, CDCl3,
d
d ppm, J Hz): d = 8.14 [d, 1H, Hi, 4J(PHi) = 10.2]; 7.12 [dd, 1H, H8,
4J(PHi) = 10.2]; 7.11 [dd, 1H, H8, 3J(H8H9) = 7.8, 4J(H8H10) =
1.5]; 6.92 [td, 1H, H10, 3J(H9H10) = 3J(H10H11) = 7.8, 4J(H8-
H10) = 1.5]; 6.74 [d, 1H, H3, 3J(H3F) = 10.8]; 6.47 [d, 1H, H11,
3J(H10H11) = 7.8]; 6.35 [t, 1H, H9, 3J(H8H9) = 3J(H9H10) = 7.8];
6.14 [d, 1H, H5, 4J(PH5) = 3.9]. 31P–{1H} NMR (12- 1.50 MHz,
3J(H8H9) = 8.1,
4J(H8H10) = 1.5];
6.98
[td,
1H,
H10,
3J(H9H10) = 3J(H10H11) = 8.1 Hz, 4J(H8H10) = 1.5]; 6.86 [d, 1H,
H3, 3J(H3F) = 10.2]; 6.58 [d, 1H, H11, 3J(H10H11) = 8.1]; 6.37 [t,
1H, H9, 3J(H8H9) = 3J(H9H10) = 8.1]; 6.21 [d, 1H, H5, 4J(PHi) =
3.9]; (CH)ferrocene = 5.19; 4.73 (br, 2H, H13, H17); (CH)ferrocene
=
CDCl3,
d ppm, J Hz): d = 35.26 [s]. MS-FAB: m/z = [(L-H2)P-
4.28. 31P–{1H} NMR (121.5 MHz, CDCl3, d ppm, J Hz): d = 24.31
[s]. 13C–{1H} NMR (125.76 MHz, CDCl3, d ppm, J Hz): d = 174.52
[d, C12, 3J(C12,P) = 3.0]; 160.15 [s, C2]; 159.20 [s, C4], 156.95 [s,
C7]; 150.56 [d, Ci, 3J(Ci,P) = 4.6]; 143.82 [s, C1]; 139.23 [d, C5,
3J(C5, P) = 7.3]; 135.13 [s, C6]; 134.20 [d, C-ortho, 2J(C-
ortho,P) = 12.3]; 132.28 [s, C10]; 131.22 [d, C-ipso, 1J(C-ip-
so,P) = 49.3]; 130.52 [d, C-para, 4J(C-para,P) = 2.1]; 128.23 [d, C-
meta, 3J(C-meta,P) = 10.7]; 122.00 [s, C9]; 117.25 [d, C3,
2J(C3,F) = 18.1]; 116.17 [s, C8]; 113.84 [s, C11]; 82.58 [s, C13,
C17]; 34.53 [s, C14, C16]; 21.51 [s, C15]. MS-FAB: m/z = [{(L-
H2)2Pd2(dppf)}H2]+ = 1414.0.
d(PPh3)]+ = 694.1
4.22. Preparation of 2-F-4-(-OCH(CH2)3CHO–B)C6H3C(H)@N[C6H11
]
(1j)
Compound
c (0.296 g, 1.27 mmol) and cyclohexylamine
(0.126 g, 1.27 mmol) were added to 50 cm3 of dry chloroform.
The mixture was heated under reflux in a modified Dean-Stark
apparatus for 10 h. After cooling to room temperature, the solvent
was evaporated to give a white solid. Yield: 85%. IR:
m(C@N)
1621sh, w cmꢁ1 1H NMR (300 MHz, CDCl3, d ppm, J Hz): d = 8.63
.
4.19. Preparation of [Pd{[2-F-4-(HO)2]BC6H2C(H)@N[20-(O)C6H4]}(PP-
h3)] (3e)
[s, 1H, Hi]; 7.98 [t, 1H, H6, 3J(H5H6) = 7.5, 3J(H6F) = 6.9]; 7.56 [d,
1H, H5, 3J(H5H6) = 7.5]; 7.47 [d, 1H, H3, 3J(H3F) = 10.8]; 5.01 [br,
2H, H7, H11]; 3.26 [m, 1H, H12], 2.01 [m, 2H, H8, H10]; 1.36 [br,
4H, H80/H100, H9, H90]. 13C–{1H} NMR (125.76 MHz, CDCl3, d
ppm, J Hz): d = 163.37 [s, C2]; 160.03 [s, C4]; 152.03 [d, Ci,
3J(CiF) = 7.9]; 130.36 [d, C5, 4J(C5F) = 5.6]; 127.11 [d, C6,
3J(C6F) = 4.0]; 126.49 [d, C1, 2J(C1F) = 16.0]; 121.49 [d, C3,
2J(C3F) = 32.7]; 83.04 [s, C7, C11]; 70.36 [s, C12]; 34.60 [s, C8,
C10]; 34.26 [s, C13, C17]; 25.59 [s, C15], 24.72 [s, C14, C16];
21.53 [ s, C9].
To a stirred solution of 3a (0.179 g, 0.27 mmol) in acetone was
added water until the apparition of a red precipitate and the result-
ing mixture stirred for a further 48 h. The red precipitate formed
was filtered of and dried under vacuum. Yield: 84%. Anal. Calc.
for C31H24BNO3FPPd: C, 59.5; H, 3.9; N, 2.2. Found: C, 59.4; H,
3.7; N, 2.3%. IR:
m .
(C@N) 1574 m cmꢁ1 1H NMR (300 MHz, CDCl3,
d ppm, J Hz): d = 8.51 [d, 1H, Hi, 4J(PHi) = 10.5]; 7.41 [dd, 1H, H8,

3606
N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
4.23. Preparation of [Pd{2-F-4-(-OCH(CH2)3CHO–B)C6H2C(H)@N[C6H11]}-
(CH3COO)]2 (5j)
para,P) = 2.1]; 129.55 [d, C-ipso, 1J(C-ipso,P) = 48.7]; 128.63 [d, C-
meta, 3J(C-meta,P) = 10.8]; 122.02 [s, C9]; 116.27 [s, C8]; 114.62
[s, C11]; 112.31 [d, C3, 2J(C3,F) = 21.4]; 74.38 [s, C
a]; 64.69 [s,
A
pressure
tube
containing
4-(-OCH(CH2)3CHO–
C14, C16], 51.03 [s, C13, C17]. 31P–{1H} NMR (121.50 MHz, CDCl3,
d ppm, J Hz): d = 34.43 [s]. ESI-MS: [(L-H2)Pd(PPh3)H]+ = 725.12.
Compound 3i was obtained as a violet solid following a similar
procedure to the one described for 3h.
B)C6H3FC(H)@N[C6H11] (f) (0.287 g, 0.91 mmol), palladium(II) ace-
tate (0.204 g, 0.91 mmol) and 20 cm3 of dry toluene was sealed un-
der argon. The resulting mixture was stirred for 24 h at 60 °C. After
cooling to room temperature, the solution was filtered through cel-
ite to remove the black palladium formed. The solvent was re-
moved under vacuum and the residue obtained was tritured with
4.26. [Pd{4-[(O(CH2)4N)C(H)(CO2H)]C6H3C(H)@N[20-(O)C6H4]}(PPh3)]
(3i)
ether to give
C40H50N2O8Pd2F2B2: C, 50.0; H, 5.3; N, 2.9. Found: C, 49.9; H, 5.3;
N, 2.8%. IR: as(COO) 1580s; s(COO)
(C@N) 1610sh, w cmꢁ1
a yellow solid. Yield: 59%. Anal. Calc. for
Yield: 37%. Anal. Calc. for C37H33N2O4PdP: C, 62.9; H, 4.7; N, 3.9.
m
,
m
m
found: C, 62.8; H, 4.6; N, 3.8%. IR:
m
(CO2H) = 1731w,
1417s. 1H NMR (300 MHz, CDCl3, d ppm, J Hz): d = 7.62 [s, 1H,
Hi]; 7.24 [s, 1H, H5]; 7.03 [d, 1H, H3, 3J(H3F) = 10.2]; 4.96 [br,
2H, H7, H11]; 3.02 [m, 1H, H12], 2.16 [s, 3H, –OAc]. 13C–{1H}
NMR (125.76 MHz, CDCl3, d ppm, J Hz): d = 181.08 [s, CH3COO–];
162.99 [s, Ci]; 159.07 [s, C2]; 156.99 [s, C4]; 155.60 [d, C1,
2J(C1F) = 1.9]; 135.89 [d, C6, 3J(C6F) = 7.0]; 133.57 [d, C5,
4J(C5F) = 2.8]; 116.1 [d, C3, 2J(C3F) = 17.7]; 82.91 [s, C7, C11];
65.22 [s, C12]; [34.65 (s), 34.55 (s) (C8/C10, C13, C17)]; 30.14 [s,
C13, C17]; [25.89 (s), 25.6 (s), 25.09 (s), (C14, C15, C16)], 24.41
[s, CH3COO–]; 21.42 [s, C9]. MS-FAB: m/z = [{(L-H2)2Pd2(CH3COO)}-
H]+ = 900.0, [(L-H)Pd(OCOCH3)]2+ = 958.9.
m
(C@N) = 1581 m. 1H NMR (300 MHz, CDCl3,
d
ppm, J Hz):
d = 7.93 [d, 1H, Hi, 4J(PHi) = 10.2]; 7.10 [m, 2H, H2, H8]; 6.99–
6.92 [m, 2H, H3, H10]; 6.52 [d, 1H, H11, 3J(H10H11) = 8.4]; 6.37
[t, 1H, H9, 3J(H8H9) = 3J(H9H10) = 7.4]; 6.03 [d, 1H, H5,
4J(PH5) = 2.7]; 3.83 [br, 4H, H14, H140, H16, H160]; 3.35 [s, 1H,
H ]; 2.23 [br, 4H, H13, H130, H17, H170]. 13C–{1H} NMR
a
(125.76 MHz, CDCl3, d ppm, J Hz): d= 172.05 [s, C12]; 156.5–
153.6 [C2, C4, C7, Ci]; 139.63 [d, C5, 3J(C5,P) = 3.5]; 137.5 [s, C1];
135.20 [s, C6]; 134.97[d, C-ortho, 2J(C-ortho,P) = 12.8]; 132.14 [s,
C10]; 131.11 [s, C-para]; 129.87 [d, C-ipso, 1J(C-ipso,P) = 48.2];
128.65 [d, C-meta, 3J(C-meta,P) = 10.7]; 121.97 [s, C3]; 118.64 [s,
C9]; 116.18 [s, C8]; 114.39 [s, C11]; 75.32 [s, Ca]; 64.68 [s, C14,
4.24. Preparation of [Pd{2-F-4-(-OCH(CH2)3CHO–B)C6H2C(H)@N[C6-
H11]}(CH3COO)-(PPh3)] (6j)
C16], 51.03 [s, C13, C17]; –COOHocl 31P–{1H} NMR (121.50 MHz,
CDCl3, d ppm, J Hz): d = 34.88 [s]. ESI-MS: [(L-H2)Pd(PPh3)H]+ =
707.13.
PPh3 (0.075 g, 0.28 mmol) was added to a suspension of 1f
(0.136 g, 0.14 mmol) in acetone (15 cm3). The mixture was stirred
for 6 h and solvent removed under vacuum to give an orange res-
idue which was recrystallized form chloroform/hexane. The yellow
solid obtained was chromatographed on a column packed with sil-
ica gel. Elution with dichloromethane/ethanol (2%) afforded the fi-
nal product as a white solid after solvent removal. Yield: 12%. Anal.
Calc. for C38H40NO4PdBFP: C, 61.5; H, 5.4; N, 1.9. Found: C, 61.4; H,
4.27. X-ray crystallographic study
Three-dimensional, room temperature X-ray data were
collected on a Bruker Smart 1k CCD and a Bruker X8 Apex diffrac-
tometers 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 posi-
tions and refined in riding mode. Chloroform solvent molecules in
the crystal of complex 2c were poorly defined and all the chlorine
atoms were disordered and, consequently, refined in two comple-
mentary positions with occupancies of approximately 50% for the
chlorine atoms of two solvent molecules and 70–30% for the
third. The chlorine atoms of the two dichloromethane solvent
molecules found in the crystal of 3c were also disordered and
refined in two positions with occupancies of approximately 50%.
Large solvent accessible [approximately 10% of the total volume]
voids were found in the crystal of 5j. The smeared electron den-
sity (maximum residual electron density 1.137 e A3) found did
not allow to identify the nature of the solvent. The program PLA-
5.3; N, 1.8%. IR:
m
(C@N) 1600 m,
mas(COO) 1555 m; ms(COO)
1300 m cmꢁ1
.
1H NMR (300 MHz, CDCl3, d ppm, J Hz): d = 8.33 [d,
1H, Hi, 4J(PHi) = 8.7]; 6.08 [dd, 1H, H3, 3J(H3F) = 11.4,
4J(H3H5) = 2.1]; 5.48 [dd, 1H, H5, 3J(PH5) = 6.0, 4J(H3H5) = 2.1];
4.59 [br, 1H, H7/H11]; 4.41 [m, 1H, H12], 2.26 [m, 2H, H8, H10],
2.18 [s, 3H, CH3COO–]. 31P–{1H} NMR (121.50 MHz, CDCl3, d ppm,
J Hz): d = 42.04 [s].
4.25. Preparation of [Pd{2-F-4-[(O(CH2)4N)C(H)(CO2H)]C6H2C(H)@N-
[20-(O)C6H4]}-(PPh3)] (3h)
To a suspension of glyoxylic acid (4.0 mg, 0.04 mmol) in dry
dichloromethane (10 cm3) was added 3b (30.5 mg, 0.04 mmol)
and morpholine (3.7 mg, 0.04 mmol) under argon, and the result-
ing solution stirred at room temperature for 7 days. The solvent
was then removed to give a pink solid, which was recrystallized
from dichloromethane/hexane. Yield: 49%. Anal. Calc. for
C37H32N2O4PdFP: C, 61.3; H, 3.9; N, 4.4. Found: C, 61.4; H, 3.7; N,
TON/SQUEEZE [38] was used to remove the effects of the disordered
solvent but no significant improvements were observed and the
original data were finally used. Refinement converged with allow-
ance for thermal anisotropy of all non-hydrogen atoms. The struc-
ture solution and refinement were carried out using the program
package SHELX-97 [39].
4.5%. IR: m(CO2H) = 1729w, m
(C@N) = 1579 m. 1H NMR (300 MHz,
CDCl3, d ppm, J Hz): d = 8.17 [d, 1H, Hi, 4J(PHi) = 10.2]; 7.11 [dd,
1H, H8, 3J(H8H9) = 8.1, 4J(H8H10) = 1.5]; 6.96 [td, 1H, H10,
3J(H9H10) = 3J(H10H11) = 8.1, 4J(H8H10) = 1.5]; 6.58 [d, 1H, H3,
3J(H3F) = 10.8]; 6.50 [d, 1H, H11, 3J(H10H11) = 8.1]; 6.39 [t, 1H,
H9, 3J(H8H9) = 3J(H9H10) = 8.1]; 5.81 [d, 1H, H5, 4J(PH5) = 3.6];
3.70 [br, 4H, H14, H140, H16, H160]; 3.32 [s, 1H, H ]; 2.15 [br, 4H,
Supplementary material
a
H13, H130 H17, H170]. 13C–{1H} NMR (125.76 MHz, CDCl3, d ppm,
J Hz): d = 173.69 [s, –COOH]; 171.01 [s, C12]; 160.24 [s, C2];
158.17 [s, C4]; 157.92 [s, C7]; 150.45 [s, Ci]; 141.81 [s, C1];
137.12 [s, C5]; 135.50 [s, C6]; 134.93 [d, C-ortho, 2J(C-
ortho,P) = 12.7]; 132.34 [s, C10]; 131.16 [d, C-para, 4J(C-
CCDC 730624, 730625 and 730626 contain the supplementary
crystallographic data for 2c, 3c and 5j. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.

N. Gómez-Blanco et al. / Journal of Organometallic Chemistry 694 (2009) 3597–3607
3607
[7] (a) A. Habtemariam, B. Watchman, B.S. Potter, R. Palmer, S. Parsons, A. Parkin,
P.J. Sadler, J. Chem. Soc., Dalton Trans. (2001) 1306;
Acknowledgments
(b) T. Okada, I.M. El-Mehasseb, M. Kodaka, T. Tomohiro, K. Okamoto, H. Okuno,
J. Med. Chem. 44 (2001) 4661;
(c) A. Gómez-Quiroga, C. Navarro-Ranninger, Coord. Chem. Rev. 248 (2004)
119;
We thank the Ministerio de Educación y Ciencia (Projects
CTQ2006-15621-C02-01/BQU and CTQ2006-15621-C02-02/BQU)
and the Xunta de Galicia (Projects INCITE07PXI103083ES and INCI-
TE08ENA209044ES) for financial support.
(d) J. Ruiz, J. Lorenzo, L. Sanglas, N. Cutillas, C. Vicente, M.D. Villa, F.X. Avilés, G.
López, V. Moreno, J. Pérez, D. Bautista, Inorg. Chem. 45 (2006) 6347.
[8] (a) D.G. Hall (Ed.), Boronic Acids: Preparations and Applications in Organic
Synthesis and Medicine, Wiley-VCH, Weinheim, 2005;
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