Syntheses, structures and redox properties of new macrocyclic triazatriolefinic Pd0 complexes and their polypyrrole modified electrodes - Application to heterogeneous catalytic Suzuki cross-coupling reactions

Article abstract of DOI:10.1002/ejic.200300724

New triolefinic macrocyclic ligands of the type (E,E,E)-1,6,11- tris(arenesulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-triene (aryl: a = ferrocenyl, b = 4-pyrrol-1-ylphenyl, c = 4-methylphenyl) and their Pd ⁰ complexes (1aab, 1abb and 1bcc) have been prepared and characterized. Further structural characterization in the solid state has also been performed by means of X-ray diffraction analysis for the complex 1bcc. The redox properties of both the ligands and their Pd complexes have been studied using cyclic voltammetric and coulombimetric techniques. In particular, complexes and ligands containing the pyrrole group do polymerize upon exposure to sufficiently positive potentials, on glassy carbon electrodes, generating highly stable modified electrodes. The new modified electrodes are efficient and selective heterogeneous catalysts for Suzuki cross-couplings, benefiting from simple removal of the catalyst from the reaction vessel. As an example, more than 2·10⁵ metal cycles are achieved at 65 °C in the coupling of phenylboronic acid and cinnamyl bromide. Iodoarenes and phenylboronic acid are also converted into biphenyls with relatively good conversions. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejic.200300724

FULL PAPER
Syntheses, Structures and Redox Properties of New Macrocyclic
Triazatriolefinic Pd0 Complexes and Their Polypyrrole Modified Electrodes ؊
Application to Heterogeneous Catalytic Suzuki Cross-Coupling Reactions
[a]
[a]
[a]
[a]
´
Antoni Llobet,* Ester Masllorens, Montserrat Rodrıguez, Anna Roglans,* and
Jordi Benet-Buchholz[b]
Keywords: Heterogeneous catalysis / Macrocyclic ligands / Palladium / Pyrroles / Modified electrodes / Electrochemistry
New triolefinic macrocyclic ligands of the type (E,E,E)-1,6,11-
tris(arenesulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-triene
(aryl: a = ferrocenyl, b = 4-pyrrol-1-ylphenyl, c = 4-methyl-
sufficiently positive potentials, on glassy carbon electrodes,
generating highly stable modified electrodes. The new modi-
fied electrodes are efficient and selective heterogeneous
phenyl) and their Pd0 complexes (1aab, 1abb and 1bcc) have catalysts for Suzuki cross-couplings, benefiting from simple
been prepared and characterized. Further structural charac- removal of the catalyst from the reaction vessel. As an ex-
terization in the solid state has also been performed by me-
ans of X-ray diffraction analysis for the complex 1bcc. The
redox properties of both the ligands and their Pd complexes
ample, more than 2·105 metal cycles are achieved at 65 °C in
the coupling of phenylboronic acid and cinnamyl bromide.
Iodoarenes and phenylboronic acid are also converted into
have been studied using cyclic voltammetric and coulombim- biphenyls with relatively good conversions.
etric techniques. In particular, complexes and ligands con-
taining the pyrrole group do polymerize upon exposure to
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
tegies based on biphasic systems (aqueous-organic[2b,3] or
fluorous-organic[4] systems) have been developed in the last
Homogeneous catalysis using transition metal (TM) decade. Organic[1b,5] and inorganic[1b,6] polymer matrices
complexes is a topic of current interest from a basic organic have also been extensively used to immobilize TM catalysts.
synthetic perspective and also from an industrial point of Among them, pyrrole electropolymerization is an attractive
view.[1] Highly efficient homogeneous catalytic systems have and convenient method given the synthetic versatility of the
been described even though their potential industrial appli- monomers and the stability of the resultant polypyrrole
cations have been hampered by the cost and difficulty in films.[7] In general, these films attached to the electrode sur-
recovering the TM catalyst and also because of the presence face via an electropolymerization process are much more
of trace amounts of the TM in the final product.
stable than those obtained by simple deposition on materi-
One of the main strategies designed to overcome the als such as polystyrene,[8] Nafion[9] or carbon paste.[10] The
above mentioned drawbacks consists of making TM cata- stability of the film is an important factor since it minimizes
lysts heterogeneous by incorporating them into solid mate- potential leaching processes from the solid surface. Further-
rials. In this context, the development of highly efficient more the high electrical conductivity of the polypyrrole
catalysts to compensate for TM complex cost and the fabri- films allows the use of the conveniently designed electroac-
cation of robust heterogeneous systems with negligible tive ancillary groups, which do not participate in the cata-
leaching, is essential in order to consider them as potential lytic transformation, but allow important aspects of the
candidates for the scale up process at an industrial plant.
process to be monitored and thus act as built in chemical
Different approaches for making TM catalysts hetero- sensors.
geneous have been recently reviewed.[1b,2] Very elegant stra-
Given the many positive aspects of the polypyrrole films
just described, it is striking that they have been scarcely
used with carbonϪcarbon bond formation catalysts in or-
der to introduce heterogeneity. In this context it is worth
[a]
´
Departament de Quımica, Universitat de Girona,
Campus Montilivi S/N, 17071 Girona, Spain
Fax: (internat.) ϩ34-972418150
E-mail: antoni.llobet@udg.es
anna.roglans@udg.es
mentioning the work of Juge et al.[11] in which they initially
´
functionalized the polypyrrole backbone with phosphane li-
gands. Subsequently the catalyst was generated in situ upon
adding an appropriate Pd0 complex.
[b]
BIS-SUA-SPA X-ray Laboratory, Geb. Q18; Raum 490,
Bayer AG,
51368 Leverkusen, Germany
Eur. J. Inorg. Chem. 2004, 1601Ϫ1610
DOI: 10.1002/ejic.200300724
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A. Llobet, E. Masllorens, M. Rodrıguez, A. Roglans, J. Benet-Buchholz
FULL PAPER
Scheme 1. Synthetic strategy; (i) (tBuOCO)2O, Et3N, DMAP, CH2Cl2, 3.5 h.; (ii) 4 equiv. (E)-1,4-dibromo-2-butene, K2CO3, CH3CN,
reflux, 15 h (for 4a), 7 h (for 4b), 23 h (for 8cc); (iii) to give 5aab: 0.5 equiv. (4-pyrrol-1-ylphenyl)sulfonamide 2b, K2CO3, CH3CN, reflux,
16 h; to give 5abb: 0.5 equiv. ferrocenesulfonamide 2a, K2CO3, CH3CN, reflux, 10 h; (iv) HCl(aq), EtOAc, room temp., 2 h for 7aab;
HCl(g), CH2Cl2, room temp., 2 h for 7abb; (v) 1 equiv. (E)-1,4-dibromo-2-butene, K2CO3, CH3CN, reflux, 16 h (for 7aab) and 20 h (for
7abb); (vi) 1.2 equiv. Pd(dba)2, THF, reflux, 1 h; (vii) 1 equiv. 2b, K2CO3, CH3CN, reflux, 24 h
During the last two years, synthetic procedures for novel 1bcc (Scheme 1). Their redox properties as well as their
types of Pd0-triazatriolefinic macrocyclic complexes such as chemical and electrochemical polymerization processes are
(E,E,E)-1,6,11-tris(arenesulfonyl)-1,6,11-triazacyclopenta- also described. Finally the capacity of the corresponding
deca-3,8,13-trienepalladium(0), 1, (see Scheme 1) have been modified electrodes to catalyze Suzuki cross-coupling reac-
reported.[12] These phosphane-free palladium(0) complexes tions has been analyzed using two different substrates.
are active and efficient catalysts for Suzuki cross-coup-
lings,[13] butadiene telomerization,[14] and alkyne hydroaryl-
ation in ionic liquids.[15] They have also been anchored in
polystyrene matrices allowing the catalyst to be separated
from reaction products by simple filtration for subsequent
re-use.[13]
Results and Discussion
Synthesis and Structures
The preparation of the triaza olefinic ligands and their
We have recently reported[16] the preparation of related unsaturated 16-electron Pd0 complexes, 1aab, 1abb and
15-membered macrocycles functionalized with ferrocenyl 1bcc, is outlined in Scheme 1, according to the general
units at the sulfonamide groups, and their palladium(0) method for the synthesis of related compounds.[12,16] Pd0
complexes. We have also reported[17] high activity and complexes 1aab and 1abb were obtained in overall yields of
quantitative recovery of palladium(0) complexes, 1, for the 51% and 36%, respectively. The low yield for complex 1abb
Heck reaction of diazonium salts with acrylates and styrene was due to the poor solubility of several intermediates con-
in a homogeneous phase.
ferred by the two pyrrole groups. Complex 1bcc was ob-
Herein we present the synthesis, spectroscopic and elec- tained in 8% overall yield by a different and more straight-
trochemical properties of new 15-membered triolefinic li- forward synthetic pathway (see Scheme 1). The main prob-
gands containing pyrrole and/or ferrocene groups together lem of this synthesis was that the bis(sulfonamide) 8cc was
with their corresponding Pd0 complexes 1aab, 1abb, and obtained as the minor product, the major one (46% yield)
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Properties of New Macrocyclic Triazatriolefinic Pd0 Complexes
FULL PAPER
being the monosulfonamide, N,N-bis[(E)-4-bromo-2-but- thus the coordination of the palladium is slightly distorted
enyl](4-methylphenyl)sulfonamide. Optimization of this step trigonal planar. Bond lengths and angles are within the ex-
was not successful.[12a]
pected ranges for this type of complex.[12b] The three nitro-
This versatile synthetic route allowed the aromatic groups gen atoms of the sulfonamides (N1, N2, N3) and the pal-
to be easily changed. Thus, these aromatic groups can be ladium center are also situated very close to a plane which
used as auxiliary substituents to perform specific functions will from now on be referred to as the main plane. The
without modifying the intrinsic coordinating properties of PdϪC bonds form a triangle with each olefinic group gen-
the ligand. In the present case, ferrocene was chosen since erating a three paddle helix centered at the palladium metal
it acts as a quantitative electrochemical sensor. On the other atom. It is also worth mentioning that the Pd complex suf-
hand, an N-bonded pyrrole group was also selected since it fers a slight disorder that is manifested in the chain of four
converts the Pd complex into a monomer which can be eas- carbon atoms (C5 to C8 with an occupancy factor of 80%
ily polymerized. At sufficiently positive anodic potentials and C5Ј to C8Ј with 20%) that links the amine atoms N2
the pyrrole group polymerizes, ejecting its α-hydrogen and N3. For the molecular conformation with 80% occu-
atoms,[7] while forming a relatively stable and insoluble con- pancy, two of the paddles are oriented up (Pd1ϪC6ϪC7,
ducting polypyrrole material. This material strongly adheres Pd1ϪC10ϪC11) and one down (Pd1ϪC2ϪC3) if the helix
to the electrode surface to which the Pd-triolefinic complex is observed in a clockwise manner (following increasing val-
has been covalently attached.
ues of the atom labeling scheme) with the helix parallel to
The crystal structure of complex 1bcc·CH2Cl2 was solved the main plane, manifesting the asymmetry of the helix with
by means of a single-crystal X-ray diffraction analysis. Fig- regard to a hypothetical pseudo C3 rotation axis perpen-
ure 1 presents the ORTEP diagram of the molecule includ- dicular to the mentioned main plane. This relative orien-
ing selected bond lengths and angles with the correspond- tation of the paddles is directly related to the conformation
ing labeling scheme.
of the three six-membered rings fused to them containing
N1 (Pd1, C11, C12, N1, C1, C2), N2 (Pd1, C3, C4, N2,
C5, C6) and N3 (Pd1, C7, C8, N3, C9, C10), respectively.
Thus when two neighboring paddles have different orien-
tations, both a chair or a boat conformation are possible
for the six member ring fused to them but when they have
the same orientation then only a distorted chair or a dis-
torted boat is possible. Indeed, two chair conformations
were obtained for the six-membered rings containing the
N1 and N2 atoms, respectively, whereas opposite orien-
tations and a distorted boat was found for N3. The dis-
ordered atoms contained in the molecule with a 20% occu-
pancy generate a paddle that has the opposite orientation
with respect to that of the molecule with the 80% occu-
pancy. The sulfonamides are oriented in such a way that
the aromatic substituents are situated at 121.9° (C13ϪC18),
128.5° (C20ϪC25) and 97.3° (C27ϪC32) with regard to the
main plane, with two of them directed over the plane, one
up (S1, S3), and one down (S2). In the S3 case the N-pyr-
rolic substituent bonded to the phenyl ring is significantly
rotated [C36ϪN4ϪC32ϪC30 torsion angle of Ϫ27.1°] to
avoid steric interactions with its neighboring hydrogen
atoms.
Figure 1. ORTEP plot (50 %) of complex 1bcc, hydrogen atoms are
omitted to fully appreciate the geometry of the complex; selected
˚
distances [A] and angles [°]: Pd1ϪC2 2.196(6), Pd1ϪC3 2.216(7),
Pd1ϪC6 2.164(17), Pd1ϪC7 2.214(9), Pd1ϪC10 2.186(7),
Pd1ϪC11 2.187(7); C10ϪPd1ϪC11 36.7(3), C10ϪPd1ϪC6
115.9(4), C11ϪPd1ϪC6 151.7(4), C10ϪPd1ϪC2 121.9(3),
C11ϪPd1ϪC2 86.7(3), C6ϪPd1ϪC2 121.6(4), C10ϪPd1ϪC3
152.4(3), C11ϪPd1ϪC3 122.5(3), C6ϪPd1ϪC3 85.5(5),
C2ϪPd1ϪC3 37.0(2), C10ϪPd1ϪC7 85.5(3), C11ϪPd1ϪC7
Redox Properties and Catalyst Immobilization
117.9(3),
C3ϪPd1ϪC7 119.4(3), C3ϪC2ϪPd1 72.3(4), C1ϪC2ϪPd1
112.4(5), C2ϪC3ϪPd1 70.7(4), C4ϪC3ϪPd1 111.7(5),
C6ϪPd1ϪC7
34.9(4),
C2ϪPd1ϪC7
151.6(3),
The redox properties of complexes 1aab, 1abb and 1bcc
were investigated by means of cyclic voltammetric and cou-
lombimetric techniques. Figure 2 (A) shows the cyclic vol-
tammograms of 1aab in CH2Cl2ϩ0.1  nBu4NPF6 at a
glassy carbon disk electrode using Ag/10 m Agϩ as the
reference electrode in the dry box. By scanning anodically
starting at 0.0 V a first wave was observed associated with
C5ϪC6ϪPd1 114.4(10), C7ϪC6ϪPd1 74.6(8), C8ϪC7ϪPd1
111.3(7), C6ϪC7ϪPd1 70.5(8), C11ϪC10ϪPd1 71.7(4),
C9ϪC10ϪPd1 115.0(5), C10ϪC11ϪPd1 71.6(4), C12ϪC11ϪPd1
115.2(5)
The molecular structure of 1bcc shows the macrocyclic the FeIII/FeII couple at E1/2 ϭ 0.561 V (Ep,a ϭ 0.680 V,
ligand, 7bcc, with all the olefinic trans double bonds coordi- Ep,c ϭ 0.442 V, ∆E ϭ 232 mV). The occurrence of a rela-
nated to the palladium. The central point of the olefins and tively high value of ∆E is a common phenomenon found in
the palladium are all nearly situated in the same plane and similar transition metal complex polymerization sys-
Eur. J. Inorg. Chem. 2004, 1601Ϫ1610
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A. Llobet, E. Masllorens, M. Rodrıguez, A. Roglans, J. Benet-Buchholz
FULL PAPER
tems,[18a] and is related to the intrinsic nature of the immob- polymerization performed on the corresponding macro-
ilized species as well as to the multiple processes which are cyclic ligand 7aab under equivalent conditions, does not
taking place simultaneously.[7]
show any significant wave around 0.8 V. This, together with
the catalytic activity of the polymerized free ligands and
complexes (vide infra), gives compelling evidence that the
Pd metal remains coordinated to the triolefinic ligands in
the generated modified electrodes containing the polypyr-
rolic films.
The films described here are highly stable. Upon scanning
more than 40 times over the Ϫ2.0 to ϩ2.0 V potential re-
gion in a fresh electrolyte solution, the decrease in charge
under the FeIII/FeII wave is insignificant. There is also some
evidence for the preservation of the coordination environ-
ment of the Pd metal center in the complex structure, since
the intensity of the anodic peak, corresponding to the Pd0
Ǟ PdII transition, also maintains its intensity.
Similar films can also be built up by maintaining the elec-
trode in the potential range 0.6Ϫ0.8 V with a potentiostat.
As an example a film grown by maintaining Eapp ϭ 0.80 V,
until a total charge of 7.22 ϫ 10Ϫ3 C had passed, yielded a
thin film with an apparent surface coverage of Γ ϭ 1.53 ϫ
10Ϫ9 mol/cm2.
It is important to point out here that the whole process
can be performed outside the dry box with carefully dried
solvents under N2 or Ar, but the Pd wave was only observed
under rigorously anhydrous conditions in the dry box.
The polymerization process was also carried out for 1aab
utilizing carbon felt electrodes (1.0 ϫ 0.5 ϫ 0.5 cm), using
the same protocols as with the glassy carbon electrodes pre-
viously described thus generating the corresponding C-felt/
poly-1aab. Under these conditions, and using the voltam-
Figure 2. Top: Growth of a C-glassy/poly-1aab during the first 20
consecutive cyclic voltammetric scans on a glassy carbon disk elec-
trode (3 mm diameter) in a 1 m  solution of 1 in CH2Cl2ϩ0.1 
TBAP (υ ϭ 0.1 V/s); bottom: cyclic voltammetric scan of C-glassy/
poly-1aab (Γ ϭ 3.10 ϫ 10Ϫ10 mol cmϪ2) upon transferring it to a
blank electrolyte solution CH2Cl2ϩ0.1  TBAP (υ ϭ 0.1 V/s); first
and four consecutive scans
A second small and broad wave was also observed in the perometric methodology, different electrodes were gener-
first scan with Ep,a ϭ 1.05 V which can be assigned to the ated with different amounts of deposited complex that,
irreversible oxidation of the pyrrole group with concomi- after proper cleaning, were used as catalysts. Their perform-
tant polymerization (the observation of this wave only in ance is described in the following section.
the first scan is typical for this kind of system and is related
The redox properties of 1abb parallel those of 1aab ex-
to the changes experienced on the electrode surface after cept that the ferrocene waves have half the intensity ob-
the deposition of the first polypyrrole layer[7b,7c]). Modified served in the previous case, as expected. For the complex
electrodes, with units of the 1aab monomer covalently 1bcc, the absence of ferrocene substituents prevents the use
bonded to the polypyrrole chain, can be obtained by scan- of electrochemical monitoring since the polypyrrole back-
ning the potential region repeatedly from 0.0 V up to 1.30 bone wave was not observed in our case, but they could
V. This is depicted in Figure 2 (A) where, upon scanning also be used for catalytic purposes. The free ligands 7aab
20 times over the indicated potential domain, a small but and 7abb can also be polymerized in the same manner as
consistent increase of the intensity wave for the FeIII/FeII described for the Pd complex 1aab generating very similar
couple was observed thus indicating the growth of the C- voltammograms except for the obvious absence of the wave
glassy/poly-1aab film on the electrode surface. Figure 2 (B) due to the irreversible oxidation of Pd.
shows the cyclic voltammetric response of the film when
transferred to a blank electrolyte solution. As in the pre-
vious case, a first wave due to the FeIII/FeII couple can be
observed (E1/2 ϭ 0.490 V, Ep,a ϭ 0.538, Ep,c ϭ 0.442, ∆E ϭ
Catalytic Activity
96 mV), as well as a second one, with Ep,a ϭ 0.83 V, that
To examine the catalytic efficiency and recovery of the C-
can be assigned to the electrochemically irreversible oxi- felt/poly-1aab materials, two model Suzuki-type cross-coup-
dation of palladium. The corresponding PdII reduction ling reactions were tested, namely the reaction of cinnamyl
takes place through a broad wave found between 0 and 0.4 bromide, 9, with phenylboronic acid, 10, to afford trans-1,3-
V. The electrochemical response of the Pd metal center can diphenylpropene, 11,[19] together with minor amounts of re-
be determined from comparison of this system with the be- gioisomer 12,[20] and that of phenylboronic acid 10 with the
havior shown in homogeneous phase by a family of related iodoarenes 13aϪb, leading to the biphenyls 14aϪb[21] (see
Pd complexes that we have described recently.[16] Also, the Scheme 2 and Table 1)
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Properties of New Macrocyclic Triazatriolefinic Pd0 Complexes
FULL PAPER
Entry 1 in Table 1 shows that at 27 °C after a reaction
time of 48 hours, up to 10 mL total volume of the system
‘‘C-felt/poly-1aab, 16.8·nmols/9, 15.0 m; 10, 22.5 m/
K2CO3, 22.5 m/toluene’’, is capable of generating
10.50 m trans-1,3-diphenylpropene, 11, and 1.65 m of its
isomeric product 3,3-diphenylpropene, 12. This implies a
substrate conversion of 81% with a TON of 7200 cycles and
a TOF of 150 cycles per hour at 48 h. When the catalytic
material had been reused in a fresh system, a sharp decrease
in its activity (entry 2) was observed due to partial deacti-
vation of the supported catalyst by undesired side reactions.
It is interesting to point out here that at this temperature
the isomeric ratio (11:12) remains relatively constant in the
range 5.0Ϫ7.0.
Scheme 2. Suzuki-type cross-coupling reactions tested
Entries 3Ϫ5 in Table 1 show a spectacular increase of the
Typically, the reaction was carried out by stirring a reac- catalyst performance when the temperature and the Sub-
tion mixture containing cinnamyl bromide, phenylboronic strate/Cat ratio are increased from 27 to 65 °C and from
acid, potassium carbonate, and the catalyst immobilized 8930 up to 13800 respectively leaving the rest of the system
onto the electrode surface in an anhydrous, degassed tolu- parameters unchanged. In particular, entry 3 shows a sub-
ene solution under nitrogen. The electrode was recovered strate conversion of 96% in 24 h with an isomeric ratio of
by removing it from the solution vessel, and washing with 15.0. This result clearly shows that upon increasing the tem-
toluene before using it again in a new reaction.
perature and the Substrate/Cat ratio, the pathways that lead
Table 1. Suzuki coupling between cinnamyl bromide, 9, and the iodoarenes, 13aϪb, with phenylboronic acid 10.
Entry
T,
°C
Substrate,
m
Cat%[a]
(nmols)
Substrate/Cat[b]
Time,
hours
Product,
m
Conversion,
%
TON
(103)
[a]
(ϫ103)
1
2
27
27
65
65
65
65
65
65
65
65
65
65
65
65
65
65
9 (15.0)
9 (15.0)
1.12.10Ϫ2
(16.80)
8.93
8.93
13.8
13.8
13.8
107.5
107.5
107.5
66.2
66.2
66.2
66.2
64.1
64.1
64.1
64.1
48
48
24
24
24
24
24
24
24
24
24
24
24
24
24
24
11 (10.50)
12 (1.65)
11 (2.85)
12 (0.45)
11 (13.50)
12 (0.90)
11 (12.90)
12 (0.45)
11 (7.20)
12 (0.45)
11 (67.20)
12 (4.00)
11 (52.80)
12 (4.00)
11 (32.80)
12 (2.40)
14a (23.61)
81
22
96
89
51
89
71
44
30
33
17.5
4
7.2
1.9
1.12.10Ϫ2
(16.80)[c]
7.27.10Ϫ3
(10.91)
3
9 (15.0)
12.5
12.2
7.0
4
9 (15.0)
7.27.10Ϫ3
(10.91)[c]
7.27.10Ϫ3
(10.91)[d]
9.30.10Ϫ4
(1.40)
5
9 (15.0)
6
9 (80.0)
95.3
79.8
48.0
19.8
21.8
11.6
2.4
7
9 (80.0)
9.30.10Ϫ4
(1.40)[c]
8
9 (80.0)
9.30.10Ϫ4
(1.40)[d]
9
13a (78.7)
13a (78.7)
13a (78.7)
13a (78.7)
13b (87.4)
13b (87.4)
13b (87.4)
13b (87.4)
1.51.10Ϫ3
(11.88)
10
11
12
13
14
15
16
1.51.10Ϫ3
(11.88)[c]
1.51.10Ϫ3
(11.88)[d]
1.51.10Ϫ3
(11.88)[e]
1.56.10Ϫ3
(13.63)
14a (25.97)
14a (13.77)
14a (3.15)
14b (18.35)
14b (17.04)
14b (8.74)
14b (3.50)
21
19.5
10
4
13.5
12.5
6.6
1.56.10Ϫ3
(13.63)[c]
1.56.10Ϫ3
(13.63)[d]
1.56.10Ϫ3
(13.63)[e]
2.7
[a] Cat. is C-felt/poly-1aab.% indicates the molar percentage of the Pd complex in the C-felt/poly-1aab polymer with respect to the substrate.
[b]
[c]
The total amount of the Pd complex in the C-felt/poly-1aab material in nanomoles is indicated in parentheses.
Molar ratio. First
[d]
[e]
reutilization. Second reutilization. Third reutilization.
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FULL PAPER
to 11 are kinetically favored with regard to those that lead 10, 118 m/K2CO3, 118 m/toluene’’ up to 10 mL total
to 12. Entries 4 and 5 show the effect of reusing the catalyst volume at 65 °C for 24 h) and without C-felt/poly-1aab is
after cleaning and soaking in a fresh solution with a slight negligible.
decrease of the activity. Several experiments were performed
in which the Substrate/Cat ratio was increased but the tem-
perature was maintained at 65 °C. A 100% conversion and
100% isomeric purity was obtained although the deacti-
Conclusion
vation became more severe upon reuse. Finally in entries
New Pd0 triolefinic complexes containing ancillary pyr-
6Ϫ8 the Substrate/Cat ratio was strongly increased up to
role and/or ferrocene groups have been prepared and
107500. This decreased conversion to 89% and isomer selec-
characterized. These groups have been attached with the
tivity to 16.8 but reduced the deactivation process on reuse
purpose of carrying out specific functions namely, electro-
(entries 7, 8) and generated an impressive overall TON of
chemical monitoring and anchoring via anodic electropoly-
223000. This is about an order of magnitude higher than
merization, respectively. The new polypyrrole modified elec-
had been described previously by anchoring similar Pd
trodes prepared in this way represent the first examples re-
complexes but using polystyrene as a solid matrix.[13]
ported in the literature of a successful phosphane-free sys-
The results described above clearly show how, for the pre- tem, capable of efficiently catalyzing Suzuki cross-coupling
sent system, the temperature and Substrate/Cat ratio are reactions. The different parameters that govern system reac-
key parameters that strongly influence the catalytic per- tivity have been established putting forward the strong ap-
formance. In particular the Substrate/Cat ratio can modu- peal of these new materials with regard to their high ther-
late: a) substrate conversion, b) isomer selectivity, c) reuse mal and air stability as well as excellent solvent resistance.
capacity and d) the TOF as well as the TON.
Iodoarene substrates were also tested for coupling reac-
Experimental Section
tions with phenyl boronic acid. Entries 9Ϫ16 in Table 1
show the results when 10 was treated with 4-iodonitroben-
zene, 13a, and iodobenzene, 13b, respectively, using the
similar catalytic system parameters as in the previous case
i.e. at 65 °C and with a reaction time of 24 hours. In these
cases conversions were lower (entries 9, 13), but the catalyst
could be reused once without any significant loss of activity
(entries 10, 14). In the second reuse (entries 11, 15) the cata-
lyst activity was reduced to 50% of its initial performance
and in the third (entries 12, 16) the activity was reduced
dramatically until only 4% substrate conversion was ob-
served.
1
General Remarks: H NMR (13C NMR) spectra were recorded at
250 MHz (62.5 MHz) or at 200 MHz (50 MHz) using Me4Si as in-
ternal standard. Chemical shifts are given in δ units. ESI mass spec-
tra were acquired using a Navigator quadrupole instrument. The
instrument was operated in the positive ion mode (ESϩ) at a probe
tip voltage of 3 kV. HRMS and ICP analyses were obtained at
´
‘‘SCAI Unidad de Espectrometrıa de Masas de la Universidad de
´
Cordoba’’, using a Micromass VG Mass Spectrometer and a
PerkinϪElmer AA spectrophotometer respectively. Elemental
analyses were determined at ‘‘Servei d’Analisi de la Universitat de
Girona’’.
`
To evaluate the degree of leaching during the catalytic
experiments in the Suzuki cross-coupling reactions, a quan-
titative Pd analysis was carried out using Atomic Absorp-
tion Spectroscopy (AAS). It was shown that about 5% of
the initial Pd had dissolved in the reaction solution during
the first 24 h of the reaction. Nevertheless, this ‘‘leached
Pd’’ does not significantly catalyze the Suzuki cross-coup-
ling reaction, as verified by removing the C-felt/poly-1aab
from a solution after a reaction time of 12 h and allowing
the process to continue under the same conditions for a
further 24 hours (see entry 9, Table 1). This experiment is
thus evidence that the catalytic process proceeds in a true
heterogeneous manner.[22]
Cyclic voltammetric experiments and controlled-potential coulo-
metry were carried out in a PAR 263A EG&G potentiostat using
a three electrode cell. Glassy carbon disk electrodes (3 mm diam-
eter) from BAS and carbon felt electrodes (0.5 ϫ 0.5 ϫ 0.5 cm)
from SOFACEL were used as the working electrodes, platinum
wires as auxiliary and Ag/10 m Agϩ as reference electrodes.
Glassy carbon disk electrodes were routinely polished with 1 µm
diamond paste. Cyclic voltammograms were performed in the dry
box or outside with carefully dried solvents under N2 or Ar, and
at a potential scan rate of 100 mV/s. All electrochemical experi-
ments were conducted in CH2Cl2 containing 0.1  (nBu4N)(PF6)
(TBAP) as the supporting electrolyte. All E1/2 values reported were
estimated from cyclic voltammetry as the average of the oxidative
and reductive peak potentials (Ep,aϩEp,c)/2. Unless explicitly men-
tioned the concentration of the complexes was approximately 1 m.
Control experiments were carried out in the absence of
the Pd complex. Suzuki coupling between cinnamyl bro-
mide, 9, and phenylboronic acid, 10, under the same con-
ditions as in entry 3 (Table 1) but without C-felt/poly-1aab
(‘‘9, 15.0 m; 10, 22.5 m/K2CO3, 22.5 m/toluene’’ up to
10 mL total volume at 65 °C for 24 h), afforded 4.65 m  of
11 and 0.3 m  of 12 (33% of conversion). The conversion
between 4-iodonitrobenzene, 13a, and phenylboronic acid,
The protocol used for the preparation of the modified electrodes
consisted of performing 20 repetitive CV scans at 100 mV/s from
Ei ϭ 0.0 V to Ec1 ϭ 1.3 V. Catalyst coverage for the modified
electrodes was evaluated from the corresponding FeIII/FeII wave
charge.
Coupling product evolution was followed on a HewlettϪPackard
5890 gas chromatograph using naphthalene as an internal stand-
10, under similar conditions as in entry 9 (‘‘13a, 78.7 m; ard.
1606  2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.eurjic.org
Eur. J. Inorg. Chem. 2004, 1601Ϫ1610

Properties of New Macrocyclic Triazatriolefinic Pd0 Complexes
FULL PAPER
Palladium(0) complexes 1aab, 1abb and 1bcc were prepared accord-
ing to a previously reported method described for macrocycles con-
taining different arene units.[12a,16] Physical properties and spectro-
scopic data for all new compounds are described below.
Starting from 4a (1.14 g, 2.3 mmol) and 2b (0.25 g, 1.1 mmol); or-
ange solid (yield 1.20 g, 1.1 mmol, 100%). M.p. 98Ϫ99 °C. IR
(KBr): ν˜ ϭ 2977, 2929, 1725, 1596, 1509, 1361, 1132 cmϪ1 1H
.
NMR (200 MHz, CDCl3): δ ϭ 1.40 (s, 18 H), 3.78 (d, J ϭ 5.5 Hz,
4 H), 4.23 (d, J ϭ 5.5 Hz, 4 H), 4.39Ϫ4.44 (m, 14 H), 4.75
(apparent t, J ϭ 2.2 Hz, 4 H), 5.39Ϫ5.65 (m, 4 H), 6.39 (t, J ϭ
2.2 Hz, 2 H), 7.19 (t, J ϭ 2.2 Hz, 2 H), 7.50 (AAЈ part of the system
AAЈBBЈ, J ϭ 8.8 Hz, 2 H), 7.83 (BBЈ part of the AAЈBBЈ system,
J ϭ 8.8 Hz, 2 H). 13C NMR (50 MHz, CDCl3): δ ϭ 28.0, 47.6,
47.7, 70.1, 70.6, 71.0, 83.8, 87.2, 111.7, 119.1, 120.0, 126.7, 128.9,
130.5, 136.9, 143.5, 151.0. ESI-MS (m/z): 1079 [M ϩ Na]ϩ, 1074
[M ϩ NH4]ϩ. C48H56Fe2N4O10S3 (1056.87): calcd. C 54.55, H 5.34,
N 5.30; found C 54.56, H 5.49, N 4.92.
(4-Pyrrol-1-ylphenyl)sulfonamide (2b): Compound was prepared by
heating to reflux sulfanilamide (2.01 g, 11.4 mmol) and 2,5-dimeth-
oxytetrahydrofuran (1.52 mL, 11.4 mmol) in glacial acetic acid ac-
cording to a method for aniline derivatives[23] (yield 1.95 g,
8.8 mmol, 75%). M.p. 246Ϫ247 °C. IR (KBr): ν˜ ϭ 3349, 3260,
1600, 1513, 1334, 1296, 1165 cmϪ1
.
1H NMR (200 MHz,
[D6]DMSO): δ ϭ 6.12 (t, J ϭ 2.2 Hz, 2 H), 7.17 (s, 2 H), 7.29 (t,
J ϭ 2.2 Hz, 2 H), 7.67 (AAЈ part of a AAЈBBЈ system, J ϭ 8.8 Hz,
2 H), 7.58 (BBЈ part of a AAЈBBЈ system, J ϭ 8.8 Hz, 2 H). 13C
NMR (50 MHz, [D6]DMSO): δ ϭ 111.9, 119.4, 119.6, 127.9,
140.8, 142.5.
(E,E)-1,11-Bis(tert-butyloxycarbonyl)-1,11-bis[(4-pyrrol-1-ylphenyl)-
sulfonyl]-6-(ferrocenylsulfonyl)-1,6,11-triazaundeca-3,8-diene
(5abb): Starting from 4b (1.30 g, 2.9 mmol) and 2a (0.38 g,
1.4 mmol); yellow solid (yield 1.10 g, 1.1 mmol, 76%). M.p.
113Ϫ114 °C. IR (KBr): ν˜ ϭ 2979, 2930, 1729, 1596, 1510, 1356,
1335, 1168 cmϪ1. 1H NMR (200 MHz, CDCl3): δ ϭ 1.35 (s, 18 H),
3.73 (d, J ϭ 5.0 Hz, 4 H), 4.37Ϫ4.39 (m, 11 H), 4.60 (apparent t,
J ϭ 2.0 Hz, 2 H), 5.51Ϫ5.79 (m, 4 H), 6.39 (t, J ϭ 2.3 Hz, 4 H),
7.18 (t, J ϭ 2.3 Hz, 4 H), 7.52 (AAЈ part of the system AAЈBBЈ,
J ϭ 8.7 Hz, 4 H), 7.95 (BBЈ part of the system AAЈBBЈ, J ϭ 8.7 Hz,
4 H). 13C NMR (50 MHz, CDCl3): δ ϭ 27.9, 47.6, 48.1, 68.6, 70.6,
70.7, 84.5, 87.5, 112.0, 119.0, 119.2, 128.7, 129.2, 130.0, 136.1,
144.0, 150.5. ESI-MS (m/z): 1036 [M ϩ Na]ϩ, 1014 [M ϩ H]ϩ.
C48H55FeN5O10S3 (1014.02): calcd. C 56.85, H 5.47, N 6.91; found
C 56.74, H 5.52, N 6.88.
N-(tert-Butyloxycarbonyl)ferrocenylsulfonamide (3a): Starting from
2a (0.80 g, 3.0 mmol); orange solid (yield 1.10 g, 3.0 mmol, 100%).
M.p. 149Ϫ151 °C.[16] IR (KBr): ν˜ ϭ 3247, 3103, 2977, 1730, 1435,
1
1339, 1243, 1133 cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ 1.42 (s,
9 H), 4.39 (s, 5 H), 4.42Ϫ4.45 (m, 2 H), 4.80Ϫ4.82 (m, 2 H), 7.05
(broad s, 1 H). 13C NMR (50 MHz, CDCl3): δ ϭ 27.9, 69.8, 70.9,
83.5, 85.8, 149.5. ESI-MS (m/z): 383 [M ϩ NH4]ϩ, 365 [M]ϩ.
C15H19FeNO4S (365.23): calcd. C 49.33, H 5.24, N 3.83; found C
49.39, H 5.28, N 3.66.
N-(tert-Butyloxycarbonyl)(4-pyrrol-1-ylphenyl)sulfonamide
(3b):
Starting from 2b (0.50 g, 2.3 mmol); colorless solid (yield 0.68 g,
2.1 mmol, 94%). M.p. 162Ϫ163 °C. IR (KBr): ν˜ ϭ 3312, 1741,
1
1594, 1511, 1415, 1340, 1151 cmϪ1. H NMR (200 MHz, CDCl3):
δ ϭ 1.42 (s, 9 H), 6.41 (t, J ϭ 2.3 Hz, 2 H), 7.17 (t, J ϭ 2.3 Hz, 2 (E,E)-1,11-Bis(ferrocenylsulfonyl)-6-[(4-pyrrol-1-ylphenyl)sulfonyl]-
H), 7.53 (AAЈ part of the AAЈBBЈ system, J ϭ 8.8 Hz, 2 H), 8.08
1,6,11-triazaundeca-3,8-diene (6aab): Starting from 5aab (0.96 g,
(BBЈ part of the AAЈBBЈ system, J ϭ 8.8 Hz, 2 H). 13C NMR 0.9 mmol); orange solid (yield 0.76 g, 0.9 mmol, 100%). M.p.
˜ ϭ 3274, 2922, 1595, 1508, 1328, 1135 cmϪ1
(50 MHz, [D6]DMSO): δ ϭ 27.5, 82.2, 111.7, 118.8, 119.1, 129.2,
95Ϫ96 °C. IR (KBr): ν
.
135.3, 143.2, 149.8. ESI-MS (m/z): 340 [M ϩ NH4]ϩ, 323 [M ϩ 1H NMR (200 MHz, CDCl3): δ ϭ 3.49 (d, J ϭ 4.8 Hz, 4 H), 3.68
H]ϩ. C15H18N2O4S (322.38): calcd. C 55.88, H 5.63, N 8.69; found
C 55.52, H 5.60, N 8.49.
(d, J ϭ 4.8 Hz, 4 H), 4.38Ϫ4.40 (m, 14 H), 4.54Ϫ4.64 (m, 6 H),
5.39Ϫ5.60 (m, 4 H), 6.40 (t, J ϭ 2.2 Hz, 2 H), 7.17 (t, J ϭ 2.2 Hz,
2 H), 7.50 (AAЈ part of the system AAЈBBЈ, J ϭ 9.0 Hz, 2 H), 7.81
(BBЈ part of the system AAЈBBЈ, J ϭ 9.0 Hz, 2 H). 13C NMR
(50 MHz, CDCl3): δ ϭ 44.3, 48.7, 68.5, 70.5, 70.7, 87.5, 111.9,
119.0, 119.8, 127.4, 128.9, 130.2, 136.2, 143.6. ESI-MS (m/z): 879
[M ϩ Na]ϩ, 857 [M ϩ H]ϩ. HRMS (m/z calcd. for [M ϩ1]):
857.0888; found 857.0880.
N-[(E)-4-Bromo-2-butenyl]-N-(tert-butyloxycarbonyl)ferrocenyl-
sulfonamide (4a): Starting from 3a (1.05 g, 2.8 mmol); orange solid
(yield 1.15 g, 2.3 mmol, 80%). M.p. 122Ϫ124 °C.[24] IR (KBr): ν˜ ϭ
1
2978, 2930, 1721, 1336, 1140 cmϪ1. H NMR (200 MHz, CDCl3):
δ ϭ 1.44 (s, 9 H), 3.93 (d, J ϭ 6.4 Hz, 2 H), 4.29 (d, J ϭ 5.0 Hz,
2 H), 4.42 (s, 5 H), 4.40Ϫ4.43 (m, 2 H), 4.79 (apparent t, J ϭ
1.9 Hz, 2 H), 5.67Ϫ5.93 (m, 2 H). 13C NMR (50 MHz, CDCl3):
δ ϭ 28.0, 31.7, 47.5, 70.2, 70.6, 71.0, 84.0, 87.0, 129.1, 130.3, 150.9.
ESI-MS (m/z): 561 [M ϩ Na ϩ CH3CN]ϩ, 515 [M ϩ NH4]ϩ, 497
[M]ϩ. C19H24BrFeNO4S (498.21): calcd. C 45.80, H 4.86, N 2.81;
found C 45.83, H 4.78, N 2.89.
(E,E)-1,11-Bis[(4-pyrrol-1-ylphenyl)sulfonyl]-6-[ferrocenylsulfonyl]-
1,6,11-triazaundeca-3,8-diene (6abb): Starting from 5abb (0.53 g,
0.5 mmol); yellow solid (yield 0.34 g, 0.4 mmol, 81%). M.p.
177Ϫ178 °C. IR (KBr): ν˜ ϭ 3277, 2923, 1597, 1509, 1333, 1159
cmϪ1 1H NMR (200 MHz, CDCl3): δ ϭ 3.52Ϫ3.54 (m, 8 H),
.
4.36Ϫ4.38 (m, 7 H), 4.54 (apparent t, J ϭ 2.0 Hz, 2 H), 5.00 (broad
s, 2 H), 5.50Ϫ5.52 (m, 4 H), 6.39 (t, J ϭ 2.2 Hz, 4 H), 7.15 (t, J ϭ
2.2 Hz, 4 H), 7.49 (AAЈ part of the system AAЈBBЈ, J ϭ 9.0 Hz, 4
H), 7.90 (BBЈ part of the system AAЈBBЈ, J ϭ 9.0 Hz, 4 H). 13C
NMR (50 MHz, CDCl3): δ ϭ 44.4, 49.2, 68.6, 70.6, 70.8, 86.8,
111.9, 119.0, 119.9, 128.6, 128.9, 129.0, 136.2, 143.8. ESI-MS
(m/z): 852 [M ϩ K]ϩ, 836 [M ϩ Na]ϩ, 814 [M ϩ H]ϩ.
C38H39FeN5O6S3 (813.79): calcd. C 56.09, H 4.83, N 8.61; found
C 56.44, H, 5.00, N 8.32.
N-[(E)-4-Bromo-2-butenyl]-N-(tert-butyloxycarbonyl)(4-pyrrol-1-yl-
phenyl)sulfonamide (4b): Starting from 3b (1.33 g, 4.3 mmol); color-
less solid (yield 1.36 g, 3.0 mmol, 72%). M.p. 109Ϫ110 °C. IR
(KBr): ν˜ ϭ 2973, 2926, 1723, 1593, 1514, 1333, 1157 cmϪ1 1H
.
NMR (200 MHz, CDCl3): δ ϭ 1.39 (s, 9 H), 3.98 (d, J ϭ 7.2 Hz,
2 H), 4.47 (d, J ϭ 5.5 Hz, 2 H), 5.79Ϫ6.08 (m, 2 H), 6.40 (t, J ϭ
2.2 Hz, 2 H), 7.17 (t, J ϭ 2.2 Hz, 2 H), 7.50 (AAЈ part of the system
AAЈBBЈ, J ϭ 9.0 Hz, 2 H), 7.99 (BBЈ part of the system AAЈBBЈ,
J ϭ 9.0 Hz, 2 H). 13C NMR (50 MHz, CDCl3): δ ϭ 27.9, 31.6,
47.3, 84.8, 112.1, 119.0, 119.2, 129.9, 130.2, 130.3, 135.9, 144.2,
150.5. ESI-MS (m/z): 493Ϫ495 [M ϩ K]ϩ, 472Ϫ474 [M ϩ NH4]ϩ,
455Ϫ457 [M ϩ H]ϩ. C19H23BrN2O4S (455.37): calcd. C 50.11, H
5.09, N 6.15; found C 49.68, H 5.00, N 6.00.
(E,E,E)-1,6-Bis(ferrocenylsulfonyl)-11-[(4-pyrrol-1-ylphenyl)-
sulfonyl]-1,6,11-triazacyclopentadeca-3,8,13-triene (7aab): Starting
from 6aab (0.76 g, 0.9 mmol); orange solid (yield 0.60 g, 0.7 mmol,
73%). M.p. 150Ϫ151 °C. IR (KBr): ν˜ ϭ 2922, 1596, 1508, 1336,
1
(E,E)-1,11-Bis(tert-butyloxycarbonyl)-1,11-bis(ferrocenylsulfonyl)-6- 1136 cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ 3.55 (broad abs., 8
[(4-pyrrol-1-ylphenyl)sulfonyl]-1,6,11-triazaundeca-3,8-diene (5aab):
H), 3.70 (broad abs., 4 H), 4.38Ϫ4.40 (m, 14 H), 4.55 (apparent t,
1607
Eur. J. Inorg. Chem. 2004, 1601Ϫ1610
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

´
A. Llobet, E. Masllorens, M. Rodrıguez, A. Roglans, J. Benet-Buchholz
FULL PAPER
J ϭ 1.9 Hz, 4 H), 5.50Ϫ5.52 (m, 6 H), 6.40 (t, J ϭ 2.2 Hz, 2 H),
3.90Ϫ4.11 (m, 2 H), 4.23Ϫ4.77 (m, 10 H), 4.41 (s, 5 H), 6.38 (br.
7.17 (t, J ϭ 2.2 Hz, 2 H), 7.51 (AAЈ part of the system AAЈBBЈ, abs., 4 H), 7.10 (br. abs., 4 H), 7.40Ϫ7.50 (m, 4 H), 7.78Ϫ7.90 (m,
4 H). ESI-MS (m/z): 972 [M ϩ H]ϩ. C42H43FeN5O6PdS3 C6H14
.
J ϭ 8.8 Hz, 2 H), 7.82 (BBЈ part of the system AAЈBBЈ, J ϭ 8.8 Hz,
2 H). 13C NMR (50 MHz, CDCl3): δ ϭ 50.6, 50.7, 68.6, 70.6, 70.8,
(1058.46): calcd. C 54.47, H 5.43, N 6.62; found C 54.33, H 5.08,
86.2, 111.9, 119.0, 120.0, 128.5, 128.9, 129.3, 130.0, 135.7, 143.7. N 6.67.
ESI-MS (m/z): 931 [M ϩ Na]ϩ, 908 [M]ϩ. C42H44Fe2N4O6S3 H2O
(926.73): calcd. C 54.43, H 5.00, N 6.05; found C 54.13, H, 4.98,
N 5.81.
.
(E,E,E)-1,6-Bis[(4-methylphenyl)sulfonyl)-11-[(4-pyrrol-1-ylphenyl)-
sulfonyl]-1,6,11-triazacyclopentadeca-3,8,13-trienepalladium(0)
(1bcc): Starting from 7bcc (0.20 g, 0.3 mmol); colorless solid (yield
0.18 g, 0.2 mmol, 78%). M.p. 172Ϫ173 °C. IR (KBr): ν˜ ϭ 2922,
(E,E,E)-1,6-Bis[(4-pyrrol-1-ylphenyl)sulfonyl]-11-(ferrocenyl-
sulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-triene (7abb): Starting
from 6abb (0.86 g, 1.1 mmol); yellow solid (yield 0.83 g, 1.0 mmol,
91%). M.p. 139Ϫ140 °C. IR (KBr): ν˜ ϭ 2920, 1731, 1596, 1507,
1
1596, 1507, 1336, 1161, 1094 cmϪ1. H NMR (200 MHz, CDCl3):
δ ϭ 1.65Ϫ1.74 (m, 4 H), 2.38 (s, 6 H), 2.81 (t, J ϭ 12.6 Hz, 2
H), 3.00Ϫ3.12 (m, 2 H), 3.70Ϫ3.80 (m, 2 H), 4.00Ϫ4.10 (m, 2 H),
4.60Ϫ4.70 (m, 4 H), 4.79 (d, J ϭ 14.4 Hz, 2 H), 6.39 (broad abs.,
2 H), 7.11 (broad abs., 2 H), 7.24Ϫ7.29 (m, 4 H), 7.45Ϫ7.54 (m, 2
H), 7.60Ϫ7.73 (m, 4 H), 7.80Ϫ7.90 (m, 2 H). 13C NMR (100 MHz,
CDCl3): 21.4, 45.0, 45.2, 48.2, 49.4, 78.1, 78.3, 78.5, 78.6, 78.7,
78.8, 82.4, 82.9, 83.0, 111.9, 118.8, 118.9, 119.8, 119.9, 126.9, 127.1,
128.7, 128.9, 129.8, 129.9, 134.7, 135.0, 135.1, 135.2, 135.9, 143.4,
1334, 1160, 1133 cmϪ1 1H NMR (200 MHz, CDCl3): δ ϭ
.
3.56Ϫ3.71 (m, 12 H), 4.37Ϫ4.39 (m, 7 H), 4.54Ϫ4.56 (m, 2 H),
5.50Ϫ5.60 (m, 6 H), 6.41 (t, J ϭ 2.2 Hz, 4 H), 7.16 (t, J ϭ 2.2 Hz,
4 H), 7.50 (AAЈ part of the system AAЈBBЈ, J ϭ 8.8 Hz, 4 H), 7.81
(BBЈ part of the system AAЈBBЈ, J ϭ 8.8 Hz, 4 H). 13C NMR
(50 MHz, CDCl3): δ ϭ 50.1, 50.7, 68.5, 70.6, 70.7, 86.0, 111.9,
119.0, 119.8, 119.9, 128.6, 128.9, 129.3, 130.1, 135.5, 143.7. ESI-
MS (m/z): 888 [M ϩ Na]ϩ, 883 [M ϩ NH4]ϩ, 866 [M ϩ H]ϩ.
HRMS (m/z calcd. for [M ϩ1]): 866.1804; found 866.1810.
143.6,
143.7.
ESI-MS
(m/z):
827
[M
ϩ
H]ϩ.
.
C36H40N4O6PdS3 CH2Cl2 (912.28): calcd. C 48.71, H 4.64, N 6.14;
found C 48.60, H 4.72, N 5.89.
(E,E,E)-1,14-Dibromo-N,N-bis[(4-methylphenyl)sulfonyl)-5,10-di-
azatetradeca-2,7,12-triene (8cc):[22] Yield 0.58 g, 0.9 mmol, 12%,
starting from 2c (2.51 g, 10.0 mmol).
Preparation of Modified Electrodes
C-felt/poly-1aab: Electrode coating was performed through cycling
the potential as described previously using a carbon felt electrode
(0.5 ϫ 0.5 ϫ 0.5 cm) used as the working electrode in a 1 m solu-
tion of 1aab in CH2Cl2 0.1  TBAP. After electropolymerization,
the modified electrode was transferred to a blank electrolyte solu-
tion and five more potential cycles were performed. The electrode
was then soaked overnight in anhydrous toluene before using it as
a heterogeneous catalyst.
(E,E,E)-1,6-Bis[(4-methylphenyl)sulfonyl)-11-[(4-pyrrol-1-ylphenyl)-
sulfonyl]-1,6,11-triazacyclopentadeca-3,8,13-triene (7bcc): Starting
from 8cc (0.15 g, 0.23 mmol) and 2b (0.05 g, 0.23 mmol); colorless
solid (yield 0.14 g, 0.2 mmol, 88%). M.p. 127Ϫ128 °C. IR (KBr):
ν˜ ϭ 2921, 1597, 1508, 1334, 1159, 1090 cmϪ1. 1H NMR (200 MHz,
CDCl3): δ ϭ 2.43 (s, 6 H), 3.66Ϫ3.75 (m, 12 H), 5.51Ϫ5.60 (m, 6
H), 6.40 (t, J ϭ 2.1 Hz, 2 H), 7.16 (t, J ϭ 2.1 Hz, 2 H), 7.30 (AAЈ
part of the system AAЈBBЈ, J ϭ 8.2 Hz, 4 H), 7.52 (AAЈ part of
the system AAЈBBЈ, J ϭ 8.6 Hz, 2 H), 7.65 (BBЈ part of the system
AAЈBBЈ, J ϭ 8.2 Hz, 4 H), 7.83 (BBЈ part of the system AAЈBBЈ,
J ϭ 8.6 Hz, 2 H). 13C NMR (50 MHz, CDCl3): δ ϭ 21.5, 50.5,
50.7, 50.8, 111.9, 119.1, 120.0, 123.9, 127.2, 128.9, 129.0, 129.6,
129.8, 135.7, 136.0, 143.6, 143.8. ESI-MS (m/z): 738 [M ϩ NH4]ϩ,
721 [M ϩ H]ϩ. C36H40N4O6S3 (720.92): calcd. C 59.98, H 5.59, N
7.77; found C 59.68, H 5.69, N 7.41.
Catalysis
1,3-Diphenylpropene, under Catalysis by C-felt/poly-1aab (11): To
a degassed mixture of cinnamyl bromide 9 (0.030 g, 0.150 mmol),
phenylboronic acid 10 (0.028 g, 0.225 mmol), anhydrous potassium
carbonate (0.031 g, 0.225 mmol), and the electrode containing the
immobilized Pd0-catalyst, C-felt/poly-1aab (see Table 1 for Pd
nmols) anhydrous toluene (10 mL) was added under N2. The mix-
ture was stirred at 65 °C for 24 hours. Product yield was calculated
by GC using naphthalene as internal standard. 1,3-Diphenylpro-
pene 11 has the same retention time as authentic material and the
correct mass by GC/MS. 1H NMR (200 MHz, CDCl3): δ ϭ 3.52
(d, J ϭ 5.9 Hz, 2 H), 6.32Ϫ6.50 (m, 2 H), 7.15Ϫ7.37 (m, 10 H).
3,3-Diphenyl-1-propene 12[24] has been identified by GC/MS analy-
(E,E,E)-1,6-Bis(ferrocenylsulfonyl)-11-[(4-pyrrol-1-ylphenyl)-
sulfonyl]-1,6,11-triazacyclopentadeca-3,8,13-trienepalladium(0)
(1aab): Starting from 7aab (0.25 g, 0.3 mmol); yellow solid (yield
0.27 g, 0.3 mmol, 88%). M.p. 211Ϫ212 °C. IR (KBr): ν˜ ϭ 2917,
1596, 1508, 1333, 1137, 904 cmϪ1 1H NMR (200 MHz, CDCl3):
.
δ ϭ 1.51Ϫ1.65 (m, 4 H), 2.75 (t, J ϭ 11.2 Hz, 2 H), 2.85Ϫ3.15 (m,
2 H), 3.65Ϫ3.72 (m, 2 H), 3.80Ϫ4.05 (m, 2 H), 4.32Ϫ4.81 (m, 14
H), 4.40 (s, 10 H), 6.38 (t, J ϭ 2.4 Hz, 2 H), 7.10 (t, J ϭ 2.4 Hz, 2
H), 7.45 (AAЈ part of the system AAЈBBЈ, J ϭ 8.7 Hz, 2 H), 7.81
(BBЈ part of the system AAЈBBЈ, J ϭ 8.7 Hz, 2 H). 13C NMR
(50 MHz, CDCl3): δ ϭ 45.1, 45.2, 48.1, 48.2, 49.3, 49.4, 49.5, 68.4,
68.5, 70.6, 70.8, 77.8, 78.1, 78.4, 78.6, 78.7, 78.9, 82.2, 82.9, 83.1,
85.4, 85.5, 85.9, 112.0, 118.9, 119.9, 128.7, 128.9, 134.9, 135.4,
1
1
sis and by H NMR spectrum. H NMR (200 MHz, CDCl3): δ ϭ
4.70 (d, J ϭ 7.2 Hz, 1 H), 4.98 (b d, J ϭ 17.0 Hz, 1 H), 5.20 (b d,
J ϭ 9.2 Hz, 1 H), 6.30 (b abs, 1 H), 7.20Ϫ7.30 (m, 10 H). The
heterogeneous catalyst was removed from the reaction vessel,
washed by stirring it in toluene and reused.
.
143.7. ESI-MS (m/z): 1014 [M]ϩ. C42H44Fe2N4O6PdS3 1/2CH2Cl2
4-Nitrobiphenyl, under Catalysis by C-felt/poly-1aab (14a), General
Method: To a degassed mixture of 4-iodonitrobenzene 13a (0.20 g,
0.79 mmol), phenylboronic acid 10 (0.15 g, 1.18 mmol), anhydrous
potassium carbonate (0.17 g, 1.18 mmol), and the modified elec-
trode, C-felt/poly-1aab (0.0015% molar) anhydrous toluene (10 mL)
was added under N2. The mixture was stirred at 65 °C for 24 hours.
The product yield was calculated by GC using naphthalene as in-
(1057.59): calcd. C 48.27, H 4.29, N 5.30; found C 48.33, H 4.32,
N 5.34.
(E,E,E)-1,6-Bis[(4-pyrrol-1-ylphenyl)sulfonyl]-11-(ferrocenyl-
sulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-trienepalladium(0)
(1abb): Starting from 7abb (0.40 g, 0.5 mmol); pale yellow solid
(yield 0.43 g, 0.4 mmol, 95%). M.p. 162Ϫ163 °C. IR (KBr): ν˜ ϭ
2923, 1596, 1508, 1334, 1160 cmϪ1. H NMR (200 MHz, CDCl3): ternal standard. 4-Nitrobiphenyl 14a has the same retention time
1
δ ϭ 1.50Ϫ1.66 (m, 4 H), 2.50Ϫ3.20 (m, 4 H), 3.70Ϫ3.80 (m, 2 H), as authentic material and the correct mass by GC/MS. The elec-
1608
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 1601Ϫ1610

Properties of New Macrocyclic Triazatriolefinic Pd0 Complexes
FULL PAPER
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W. A. Herrmann, B. Cornils, Angew. Chem. 1997, 109,
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X-ray Structure Determination of 1bcc: Very small colorless and
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small crystal needle with the dimensions 44 ϫ 14 ϫ 6 µm. Molecu-
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˚
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[4a]
11.1889(12), b ϭ 14.1440(14), c ϭ 14.4425(14) A, α ϭ 117.683(4)°,
´
I. T. Horvath, Immobilization by Other
3
˚
β ϭ 100.507(4)°, γ ϭ 90.266(3)°, V ϭ 1979.5(3) A , space group
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¯
ments were made on a Siemens P4 diffractometer equipped with a
SMART-CCD-1000 area detector, a MACScience Co. rotating an-
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mens low temperature device LT2 (T ϭ Ϫ120 °C). The measure-
ments were made in the range 1.63 to 27.50°. 24003 reflections
were collected of which 8939 were unique (Rint ϭ 0.1292) and 3783
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using ω and scans. Programs used: Data collection Smart V. 5.060
(Bruker AXS, 1999), data reduction Saint ϩ Version 6.02 (Bruker
AXS 1999) and absorption correction SADABS (max./min. trans-
mission: 1.000000/0.709584, Bruker AXS 1999). Structure solution
and refinement using SHELXTL Version 5.10 (Sheldrick, Univer-
sity of Göttingen, Germany, 1998). The structure was solved by
direct methods and refined by full-matrix least-squares against F2.
All calculated hydrogen positions were refined and constrained. Fi-
nal R1 [I Ͼ 2σ(I)] ϭ 0.0698 and wR(F2) [I Ͼ 2σ(I)] ϭ 0.1459. The
number of refined parameters was 503.
2147Ϫ2149; Angew. Chem. Int. Ed. Engl. 1997, 36, 2057Ϫ2059.
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I. T. Horvath, Acc. Chem. Res. 1998, 31, 641Ϫ650.
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1610
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www.eurjic.org
Eur. J. Inorg. Chem. 2004, 1601Ϫ1610