Synthesis and structure of a chiral dinuclear palladium(0) complex with a 30-membered hexaolefinic macrocyclic ligand

Article abstract of DOI:10.1016/j.jorganchem.2007.03.025

Selective and efficient preparation of a new chiral dipalladium(0) complex with an olefinic macrocyclic ligand named (E,E,E,E,E,E)-1,6,11,16,21,26-hexakis[(4-methylphenyl)sulfonyl]-1,6,11,16,21,26-hexaazacyclotriaconta-3,8,13,18,23,28-hexaenedipalladium(0

Full text of DOI:10.1016/j.jorganchem.2007.03.025

Journal of Organometallic Chemistry 692 (2007) 2997–3004
www.elsevier.com/locate/jorganchem
Synthesis and structure of a chiral dinuclear palladium(0) complex
with a 30-membered hexaolefinic macrocyclic ligand
a
a,
b
c
Anna Pla-Quintana , Anna Roglans *, Teodor Parella , Jordi Benet-Buchholz
a
Department of Chemistry, Universitat de Girona, Campus de Montilivi, E-17071 Girona, Spain
b
`
Servei de RMN, Universitat Autonoma de Barcelona, Cerdanyola, E-08193 Barcelona, Spain
X-Ray Diffraction Unit, Institute of Chemical Research of Catalonia (ICIQ), Avda. Paı¨sos Catalans, 16, E-43007 Tarragona, Spain
c
Received 20 February 2007; received in revised form 12 March 2007; accepted 12 March 2007
Available online 24 March 2007
Dedicated to Professor Miguel Yus on the occasion of his 60th birthday.
Abstract
Selective and efficient preparation of a new chiral dipalladium(0) complex with an olefinic macrocyclic ligand named (E,E,E,E,E,E)-
1,6,11,16,21,26-hexakis[(4-methylphenyl)sulfonyl]-1,6,11,16,21,26-hexaazacyclotriaconta-3,8,13,18,23,28-hexaenedipalladium(0) (5) is
reported. Dinuclear palladium(0) complex 5 has been fully characterized by means of NMR spectroscopy and X-ray diffraction analysis.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Palladium; Dinuclear complexes; Alkene ligands; Macrocycles; Structural elucidation
1. Introduction
which revealed that the two palladium atoms are bridged
by the three dba ligands through the olefin bonds. How-
ever, in this case the two palladium(0) centres are separated
In the field of organometallic chemistry, many ligand
systems have been developed in an attempt to find a way
of locking two metals sufficiently close together as to pro-
vide new reactivity patterns [1]. In the particular case of
organopalladium chemistry, a number of Pd(I)–Pd(I) dinu-
clear complexes, which have r-bonds, have been isolated
and characterized, but much less effort has been devoted
to complexes with palladium in other electronic configura-
tions [2]. Some d10–d10 Pd(0)2 complexes with a short
Pd–Pd separation in which the dinuclear cluster is stabi-
lized by two [3] or three bridging bisphosphines [4] have
been structurally characterized. It is well known that ole-
fins are also good ligands for the stabilization of palla-
dium(0). An example of this is the catalytically active
Pd2(dba)3 complex [5]. The molecular structure of Pd2
(dba)3 was determined by X-ray diffraction analysis [6],
˚
by approximately 3 A, a distance consistent with two non-
interacting palladium atoms. Interestingly, the control of
the Pd–Pd bond distance in dinuclear complexes can afford
promising materials such as nano-structured palladium
particles [2].
In recent years our group has been researching the synthe-
sis of new polyolefinic nitrogen-containing macrocycles and
their ability to coordinate palladium(0) metal [7]. Mononu-
clear palladium(0) complexes of types 1–4 (Fig. 1) have been
prepared and fully characterized by means of NMR spec-
troscopy and X-ray diffraction [8]. These studies have dem-
onstrated that the incorporation of a palladium atom into
the cavity of a variety of sizeable polyunsaturated azamacro-
cyclic ligands forms stable tricoordinate complexes. The ole-
fins in the preorganized macrocyclic ligands are ideally
pre-positioned for palladium(0)-complex formation. Fur-
thermore, palladium(0) complexes of type 1 showed excel-
lent catalytic activity in certain carbon-carbon bond
formation reactions [7,9].
*
Corresponding author. Tel.: +34 972 418275; fax: +34 972 418150.
E-mail address: anna.roglans@udg.es (A. Roglans).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.03.025

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A. Pla-Quintana et al. / Journal of Organometallic Chemistry 692 (2007) 2997–3004
bromo compound 7 [7] in refluxing acetonitrile in the pres-
SO2 Ar
SO2 Ar
N
ence of K2CO3, which afforded a 94% yield of intermediate
8. Compound 8 was deprotected with trifluoroacetic acid
(TFAA) at room temperature and the resulting intermediate
9 was dialkylated again by treatment with two equivalents of
7 in the presence of K2CO3 as a base. A 76% yield of com-
pound 10 was obtained from two steps. Deprotection of
the BOC groups of derivative 10 was again achieved using
trifluoroacetic acid in methylene chloride at room tempera-
ture. The desired macrocycle was obtained after a cyclisation
reaction of an equimolar mixture of compound 11 with the
commercially available (E)-1,4-dibromobutene 12 in reflux-
ing acetonitrile and K2CO3 as a base. A 59% yield of hexa-
azamacrocycle 13 was obtained and an overall yield of
37% was achieved from the five-step synthesis.
O2S
Ar
N
n
N
Pd
Pd
Ar O2S
N
N
SO2 Ar
N
N
O2S
Ar
SO2 Ar
1
2
n = 1, 2
N
SO2 Ar
N
SO2 Ar
E or Z
(
)
Ar O2S
N
Pd
Pd
O2S
N
Ar
N
N
SO2 Ar
SO2
Ar
Macrocycle 13 is a colourless solid which gives correct
4
3
1
elemental analysis and presents simple H and 13C NMR
spectra due to its high symmetry. The 12 methylene units
in the ring appear at d ꢀ 3.6 ppm as a broad singlet and
the 12 equivalent olefinic protons also give a broad singlet
at d ꢀ 5.4 ppm. Finally, a singlet at d ꢀ 2.4 ppm (CH3C6
H4–) and aromatic protons at d ꢀ 7.26–7.67 ppm complete
the expected resonances for the target compound. In the
13C NMR spectrum, the chemical shift of the olefinic car-
bon atoms is observed at d ꢀ 129.2 ppm and the 12 CH2
carbon atoms appear at d ꢀ 48.8 ppm. The ESI mass spec-
trum of compound 13 shows a peak at m/z 1339 corre-
sponding to the molecular ion [M+H]+ together with
other cation adducts such as [M+NH4]+ at m/z 1356 and
[M+K]+ at m/z 1377.
Fig. 1. General structure of monopalladium(0) complexes of polyunsat-
urated azamacrocyclic ligands.
Given that the 25-membered macrocycles of type 2
(n = 2) coordinate a single palladium(0) atom with three
of its five olefins, we assumed that a 30-membered macro-
cyclic ligand could stabilize a dinuclear palladium–palla-
dium motif inside the ring cavity bringing the two
palladium atoms close to each other. As part of our ongo-
ing research into the coordination properties of polyunsat-
urated macrocyclic ligands, and bearing in mind the
scarcity of stable palladium complexes of polyolefinic mac-
rocycles together with their potential use in catalysis and
the design of new chiral topologies, we wish to report a
highly efficient synthesis and the structural characterization
of a dipalladium(0) complex of a 30-membered hexaaza-
macrocycle 5 (Fig. 2).
Dipalladium(0) complex 5 was easily prepared by
ligand-exchange using Pd2(dba)3 as a source of palla-
dium(0) in a solution of the 30-membered macrocycle 13
in acetonitrile (Scheme 2).
Compound 5 was purified by column chromatography
on silica-gel. The compound was air and moisture-stable
and gave a correct elemental analysis. The inclusion of
two palladium atoms into the ring cavity was easily con-
firmed by ESI-MS analysis, which showed a peak at m/z
1575 consistent with the adduct of the dipalladium complex
with sodium [M+Na]+. Fig. 3 shows the 1H and 13C NMR
chemical shift assignments for the dinuclear Pd-complex 5.
The simple 1H and 13C NMR spectra of complex 5 confirm
the presence of a high symmetry in the molecule. The gen-
eral conclusions regarding the structure of 5 in solution are
in line with those reached after performing detailed NMR
studies into similar 15-, 20- and 25-membered azamacro-
cylic complexes [8]. Each palladium atom coordinates inde-
pendently with three olefin systems to form a highly rigid
five-ring system consisting of consecutively fused three
and six-membered rings, as shown in Fig. 3.
2. Results and discussion
The preparation of hexaazamacrocyclic ligand 13 [10] is
shown in Scheme 1. The synthesis started with the condensa-
tion of butendiamine derivative 6 [7] with two equivalents of
O2S
N
O2S
N
S N
O2
Pd
Pd
N
N
SO2
O2S
N
O2S
For each palladium metal six asymmetric carbon atoms
are formed resulting from the coordination of the palla-
dium to the two olefin faces of each double bond in the
macrocycle [11]. However, since the three double bonds
are of defined stereochemistry trans, three independent
pairs of asymmetric centres must be considered. Therefore,
5
Fig. 2. Structure of the dipalladium(0) complex of a 30-membered
hexaazamacrocyclic ligand.

A. Pla-Quintana et al. / Journal of Organometallic Chemistry 692 (2007) 2997–3004
2999
Ar
O2S
O
OC(CH3)3
N
C
O
H
N
C
OC(CH3)3
Br
Ar
Ar SO2N
S
N
Ar
S
N
O2
O2
TFAA / CH2Cl2
7
rt
K2CO3 / CH3CN, reflux
(94%)
O
(83%)
H
N
C
OC(CH3)3
Ar
N
SO2
Ar
Ar SO2
O2S
Ar
8
6
Ar
H
O2S
Ar
O2S
O2S
N
N
N
O
C
OC(CH3)3
C
OC(CH3)3
Br
Ar
Ar
S N
S
N
O
Ar SO2N
O2
O2
7
O
C
OC(CH3)3
Ar
K2CO3 / CH3CN, reflux
(92%)
N
N
SO2
N
SO2
H
N
O2S
N
O2S
O2S
Ar
Ar
Ar
Ar
Ar
9
10
Ar
O2S
N
Ar
Ar
O2S
N
O2S
N
Ar
O2S
N
H
Ar
S
N
S
N
Br
O2
Br
O2
TFAA / CH2Cl2
12
rt
K2CO3 / CH3CN, reflux
(59%)
H
N
O2S
(87%)
N
N
N
N
O2S
N
O2S
O2S
Ar SO2
Ar
Ar SO2
Ar
Ar
Ar
Ar =
13
11
Scheme 1. Synthesis of hexaazamacrocycle 13.
O2S
O2S
N
O2S
N
N
O2S
N
S
N
S
N
O2
O2
Pd2(dba)3
Pd
Pd
CH3CN, rt
(63%)
N
O2S
N
O2S
N
SO2
N
SO2
N
O2S
N
O2S
13
5
Scheme 2. Synthesis of dipalladium(0) complex 5.
only eight stereoisomers grouped into four pairs of enanti-
omers should be possible. From NMR data all six-
membered sub-structures present the same highly rigid
chair conformation as deduced from the well characterized
axial and equatorial position of the a-nitrogen methylene
protons (Dd about 3 ppm) and from clear NOE observed
between the 1,3-diaxially positioned protons at 1.61 and
1.37 ppm. Therefore, it can be stated that stereoisomers
containing palladacyclohexanic rings with a twist confor-
mation are not formed, which leaves just four stereoiso-
mers with overall chair-chair conformation. Obviously, all
three cyclopropane moieties show a trans rearrangement.
On the other hand, the central 12-membered ring shows a
more flexible structure as seen from the smaller chemical
shift difference in methylene groups (Dd about 0.6 ppm
between geminal protons). Fig. 4 shows the most stable
stereoisomers expected for complex 5, a meso form
A1/A2 and a pair of enantiomers A3/A4. In terms of
molecular symmetry, the meso structure A1/A2 has a sym-
metry plane intersecting the two nitrogen atoms N1/N16
and a C2-axis crossing through the two palladium atoms.
On the other hand, each enantiomer A3/A4 presents three

3000
A. Pla-Quintana et al. / Journal of Organometallic Chemistry 692 (2007) 2997–3004
tact surface and the overall molecular size of 5 with respect
to 13 were not altered.
O2S
The structure of 5 was confirmed by X-ray diffraction
study [13]. A perspective view of the molecule is shown in
Fig. 5. Complex 5 crystallizes from dichloromethane as
the main solvent in a centrosymmetrical space group with
three disordered dichloromethane molecules in the crystal
cell. In the crystal packing of compound 5, a local C2-sym-
metry is shown with the palladium atoms coordinated to
three olefinic bonds. In agreement with the NMR results
the four palladacyclohexanic rings observed in the crystal
structure present a chair conformation. The only pair pres-
ent in the solid state is the enatiomeric pair A3/A4 (the
observation of a stereoisomer in a centrosymmetrical space
group implies the existence of its enantiomer in the struc-
ture). The olefinic trans double bonds are coordinated to
the palladium(0) in a trigonal planar coordination geome-
try. The planes formed by the coordination sphere of Pd1
and Pd2 form an angle of 45ꢁ. The Pd1–Pd2 distance is
N
O2S
N
S N
O2
Pd
Pd
3.98 80.1
4.06 / 3.50
50.6
N
O2S
4.62 / 1.61 48.3
143.6
N
N
O2S
2.42 21.5
SO2
134.4
7.30
4.05
85.4
3.41
74.2
7.59
127.2
129.8
138.6
143.9
2.52 21.6
7.72
127.1
7.45
130.1
4.31 / 1.37
48.0
Fig. 3. 1H and 13C NMR (in italics) chemical shift assignments for
dipalladium complex 5.
˚
C2-axis, one intersecting N1/N16 atoms, another centered
in the middle of the molecule just perpendicular to the
drawing and the other passing through the two palladium
of 7.3 A similar to the intermolecular distances of the
˚
metallic atoms (Pd1(molecule A)–Pd1(molecule B) 8.1 A
˚
and Pd2(molecule A)–Pd2(molecule B) 7.2 A). In compar-
atoms. Both H and 13C NMR data are fully consistent
1
ing distances between two externally located double bonds
and their corresponding palladium atoms (Pd1/C23–C24
and Pd2/C10–C11) and Pd/double bond distances which
are situated more internally, we find, taking into account
standard deviations, that the former are slightly longer.
In summary, we have prepared a 30-membered hexao-
lefinic azamacrocyclic ligand 13 by a highly efficient synthe-
sis in terms of yields and simplicity. Macrocycle 13 has
shown a complexing ability towards palladium(0) and so
generating a novel chiral dinuclear palladium complex.
with the three possible stereoisomers, but according to
the X-ray structure (see below) we can suppose that the
enantiomeric pair A3/A4 is the only structure formed.
We performed PGSE studies [12] to confirm the inclu-
sion of two palladium atoms inside the macrocylic cavity.
Whereas the free ligand 13 presents a diffusion coefficient
of 5.13 · 10ꢁ10 m2/s, complex 5 shows a value of 4.84 ·
10ꢁ10 m2/s. These similar values agree with the fact that
although the molecular weight increased by 15%, the con-
Ar
O2S
Ar
O2S
Ar
2
N
O2S
N
Ar
29
4
30
3
N
O2S
N
28
5
27
N
225
Ar
S
N
Ar
S
7
O2
O
8
Pd
Pd
24
23
22
Pd
14
Pd
9
10
N
N
N
12
13
O2S
N
N
O2S
O2S
Ar SO2
Ar
N
19 17
SO
Ar
Ar
2 20
18
15
Ar
O2S
Ar
meso from A1/A2
Ar
Ar
O2S
O2S
Ar
Ar
N
O2S
N
O2S
N
N
Ar
S
N
Ar
S
N
O2
O2
Pd
Pd
Pd
Pd
N
O2S
N
O2S
N
SO2
N
SO2
N
O2S
N
O2S
Ar
Ar
Ar
Ar
Ar
Ar
A3 (3R, 4
R, 8
S, 9
S, 13
R
, 14R, 18R, 19R, 23
S, 24S
, 28R, 28
R
)
A4 (3S, 4S, 8R, 9R, 13S, 14S, 18S, 19S, 23R, 24R, 28S, 28S)
Fig. 4. Expected stereoisomers for palladium(0) complex 5, a meso form A1/A2, and a pair of enantiomers A3/A4.

A. Pla-Quintana et al. / Journal of Organometallic Chemistry 692 (2007) 2997–3004
3001
˚
Fig. 5. ORTEP plot (50%) obtained from single crystal X-ray structure analysis of 5. Selected bond distances (A): C(2)–C(3): 1.383(5); C(6)–C(7): 1.362(6);
C(10)–C(11): 1.384(6); C(14)–C(15): 1.397(5); C(18)–C(19): 1.391(7); C(22)–C(23): 1.376(6); Pd(1)–C(2): 2.187(4); Pd(1)–C(3): 2.177(4); Pd(1)–C(18):
2.185(4); Pd(1)–C(19): 2.190(4); Pd(1)–C(22): 2.202(4); Pd(1)–C(23): 2.213(4); Pd(2)–C(6): 2.197(4); Pd(2)–C(7): 2.178(4); Pd(2)–C(10): 2.225(5); Pd(2)–
C(11): 2.217(4); Pd(2)–C(14): 2.188(4); Pd(2)–C(15): 2.172(5).
The dipalladium complex was characterized by NMR and
X-ray diffraction analysis. The rigid conformation of the
two triolefin–palladium moieties in the macrocyclic ring
separates the two metal atoms to a distance of approx.
7 A and prevents their interaction. Applications of 5 in
catalysis are now under investigation.
acquired using a Navigator quadrupole instrument (Finni-
gan AQA ThermoQuest) equipped with an electrospray ion
source. Elemental analyses were determined by the Chem-
ical Analysis Service of the University of Girona.
1,4-Dibromobutene (12), is commercially available and
was used without further purification. Butendiamine deriv-
ative 6 and bromo compound 7 were prepared as previ-
ously reported [7].
˚
3. Experimental
3.1. General methods
3.2. Preparation of (E,E,E)-1,16-bis(tert-butyloxicarbonyl)-1,
6,11,16-tetrakis[(4-methylphenyl)sulfonyl]-1,6,11,16-tetra-
azahexadeca-3,8,13-triene (8)
IR spectra were recorded with a FT-IR using a single
reflection ATR system as a sampling accessory. H NMR
1
(13C NMR) spectra were recorded at 200 MHz and
500 MHz (50 MHz and 125 MHz) using Me4Si as the inter-
nal standard. Chemical shifts are given in d units. NMR
experiments were recorded at 298 K on an AVANCE500
Bruker spectrometer equipped with a cryogenically cooled
A mixture of (E)-N,N0-bis[(4-methylphenyl)sulfonyl]-2-
buten-1,4-diamine (6) (1.20 g, 3.0 mmol), and anhydrous
potassium carbonate (2.84 g, 20.5 mmol) in acetonitrile
(70 mL) was heated at 70 ꢁC for 30 min in a 250 mL
round-bottomed flask equipped with magnetic stirring
and a condenser. Then, a solution of N-[(E)-4-bromo-2-
butenyl]-N-(tert-butyloxicarbonyl)-(4-methylphenyl)sulfon-
amide, (7), (2.48 g, 6.1 mmol) in acetonitrile (80 mL) was
added and the mixture was refluxed for 6 h (TLC monitor-
ing). After cooling to room temperature, the salts were fil-
tered off and the filtrate was evaporated. The residue was
1
probe. Full H and 13C NMR resonance assignments were
confirmed from 2D COSY and HSQC methods. Self-diffu-
sion coefficient measurements were made under routine
conditions using the BPLED pulse scheme with a diffusion
time of 150 ms and with sample rotation of 20 Hz to avoid
undesired convection effects [14]. ESI mass spectra were

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A. Pla-Quintana et al. / Journal of Organometallic Chemistry 692 (2007) 2997–3004
purified by column chromatography through silica gel with
mixtures of hexane–dichloromethane–ethyl acetate of
increasing polarity as the eluent (from 8:1:1 to 6:2:2) to
(1.51 g, 1.8 mmol) and anhydrous potassium carbonate
(1.91 g, 13.8 mmol) in acetonitrile (65 mL) was heated at
70 ꢁC for 30 min in a 250 mL round-bottomed flask
equipped with magnetic stirring and a condenser. Then, a
solution of N-[(E)-4-bromo-2-butenyl]-N-(tert-butyloxicar-
bonyl)-(4-methylphenyl)sulfonamide (7), (1.46 g, 3.6 mmol)
in acetonitrile (80 mL) was added and the mixture was
refluxed for 20 h (TLC monitoring). After cooling to room
temperature, the salts were filtered off and the filtrate was
evaporated. The residue was purified by column chroma-
tography through silica gel with mixtures of dichlorometh-
ane-ethyl acetate of increasing polarity as the eluent (from
20:0 to 20:2) to afford (E,E,E,E,E)-1,26-bis(tert-butyloxi-
carbonyl)-1,6,11,16,21,26-hexakis[(4-methylphenyl)sulfo-
nyl]-1,6,11,16,21,26-hexaazahexacosa-3,8,13,18,23-pentaene
(10), as a colourless solid (2.67 g, 92% yield); m.p. 133–
135 ꢁC (dichloromethane–diethyl ether–hexanes); IR
afford
(E,E,E)-1,16-bis(tert-butyloxicarbonyl)-1,6,11,16-
tetrakis[(4-methylphenyl)sulfonyl]-1,6,11,16-tetraazahexa-
deca-3,8,13-triene (8), as a colourless solid (2.97 g, 94%
yield); m.p. 138–139 ꢁC (hexane–dichloromethane–ethyl
acetate); IR (ATR) 2923, 1713, 1331, 1133 cmꢁ1 1H
;
NMR (200 MHz, CDCl3) 1.32 (s, 18H), 2.42 (s, 12H),
3.68–3.78 (m, 8H), 4.32–4.37 (m, 4H), 5.37–5.77 (br abs,
6H), 7.30 (m, 8H), 7.67 (BB0 part of the AA0BB0 system,
J = 8.2 Hz, 4H), 7.76 (BB0 part of the AA0BB0 system,
J = 8.4 Hz, 4H); 13C NMR (50 MHz, CDCl3) 21.4, 21.5,
27.8, 47.5, 48.0, 48.2, 84.3, 127.1, 127.9, 128.3, 128.8,
129.2, 129.7, 137.0, 137.1, 143.3, 144.2, 150.6; ESI-MS
(m/z) 1041 [M+H]+, 1058 [M+NH4]+, 1063 [M+Na]+.
Anal. Calc. for C50H64N4O12S4 (1041.3): C, 57.67; H,
6.19; N, 5.38; S, 12.32. Found: C, 57.64; H, 6.51; N, 5.40;
S, 12.14%.
(ATR) 2927, 1716, 1355, 1335, 1145, 1177 cmꢁ1 1H
;
NMR (200 MHz, CDCl3) 1.31 (s, 18H), 2.42 (s, 18H),
3.64–3.76 (m, 16H), 4.30–4.36 (m, 4H), 5.40–5.69 (br abs,
10H), 7.24–7.32 (m, 12H), 7.65 (BB0 part of the AA0BB0
system, J = 8.4 Hz, 4H), 7.66 (BB0 part of the AA0BB0 sys-
tem, J = 8.4 Hz, 4H), 7.75 (BB0 part of the AA0BB0 system,
J = 8.4 Hz, 4H); 13C NMR (50 MHz, CDCl3) 21.5, 27.8,
47.5, 48.2, 48.4, 84.4, 127.2, 127.9, 128.2, 128.7, 128.9,
129.1, 129.3, 129.8, 136.9, 137.2, 143.4, 144.3, 150.6; ESI-
MS (m/z) 1487 [M+H]+, 1504 [M+NH4]+, 1509
[M+Na]+, 1525 [M+K]+. Anal. Calc. for C72H90N6O16S6
(1487.9): C, 58.12; H, 6.10; N, 5.65; S, 12.93. Found: C,
58.23; H, 6.38; N, 5.64; S, 12.85%.
3.3. Preparation of (E,E,E)-1,6,11,16-tetrakis[(4-
methylphenyl)sulfonyl]-1,6,11,16-tetraazahexadeca-3,8,13-
triene (9)
Trifluoroacetic acid (6 mL, 77.9 mmol) was added drop-
wise to a solution of (E,E,E)-1,16-bis(tert-butyloxicar-
bonyl)-1,6,11,16-tetrakis[(4-methylphenyl)sulfonyl]-1,6,11,
16-tetraazahexadeca-3,8,13-triene (8), (2.63 g, 2.5 mmol) in
dichloromethane (10 mL). The mixture was stirred at room
temperature for 9 h (TLC monitoring). Then, the solution
was evaporated and the excess of trifluoroacetic acid was
eliminated by means of a nitrogen gas flow. The white res-
idue was purified by column chromatography through sil-
ica gel with mixtures of dichloromethane–ethyl acetate of
increasing polarity as the eluent (from 20:0 to 20:2) to
3.5. Preparation of (E,E,E,E,E)-1,6,11,16,21,26-hexakis
[(4-methylphenyl)sulfonyl]-1,6,11,16,21,26-
hexaazahexacosa-3,8,13,18,23-pentaene (11)
afford
(E,E,E)-1,6,11,16-tetrakis[(4-methylphenyl)sulfo-
Trifluoroacetic acid (5 mL, 64.9 mmol) was added
dropwise to a solution of (E,E,E,E,E)-1,26-bis(tert-butyloxi-
carbonyl)-1,6,11,16,21,26-hexakis[(4-methylphenyl)sulfo-
nyl]-1,6,11,16,21,26-hexaazahexacosa-3,8,13,18,23-pentaene
(10), (2.35 g, 1.6 mmol) in dichloromethane (10 mL). The
mixture was stirred at room temperature for 6 h (TLC
monitoring). Then, the solution was evaporated and the
excess of trifluoroacetic acid was eliminated by means of
a nitrogen gas flow. The white residue was purified by col-
umn chromatography through silica gel with mixtures of
dichloromethane–ethyl acetate of increasing polarity as
the eluent (from 25:0 to 23:2) to afford (E,E,E,E,E)-
1,6,11,16,21,26-hexakis[(4-methylphenyl)sulfonyl]-1,6,11,16,
21,26-hexaazahexacosa-3,8,13,18,23-pentaene (11), as a
colourless solid (1.77 g, 87% yield); m.p. 151–153 ꢁC
(ethyl acetate–dichloromethane); IR (ATR) 3271, 2924,
nyl]-1,6,11,16- tetraazahexadeca-3,8,13-triene (9), as a col-
ourless solid (1.75 g, 83% yield); m.p. 158–160 ꢁC
(dichloromethane–ethyl acetate); IR (ATR) 3268, 2923,
1322, 1155 cmꢁ1 1H NMR (200 MHz, CDCl3) 2.41 (s,
;
6H), 2.44 (s, 6H), 3.44–3.48 (m, 4H), 3.64–3.69 (m, 8H),
5.12–5.14 (m, 2H), 5.38–5.64 (br. abs, 6H), 7.25–7.34 (m,
8H), 7.67 (BB0 part of the AA0BB0 system, J = 8.4 Hz,
4H), 7.71 (BB0 part of the AA0BB0 system, J = 8.4 Hz,
4H); 13C NMR (50 MHz, CDCl3) 21.5, 44.3, 48.8, 49.3,
127.1, 127.2, 127.9, 129.2, 129.7, 129.8, 130.0, 136.5,
136.8, 143.4, 143.6; ESI-MS (m/z) 841 [M+H]+. Anal.
Calc. for C40H48N4O8S4 (841.1): C, 57.12; H, 5.75; N,
6.66; S, 15.25. Found: C, 56.70; H, 5.95; N, 6.43; S, 14.87%.
3.4. Preparation of (E,E,E,E,E)-1,26-bis(tert-butyloxi
carbonyl)-1,6,11,16,21,26-hexakis[(4-methylphenyl)-
sulfonyl]-1,6,11,16,21,26-hexaazahexacosa-3,8,13,18,23-
pentaene (10)
1
1716, 1334, 1156 cmꢁ1; H NMR (200 MHz, CDCl3) 2.40
(s, 6H), 2.42 (s, 12H), 3.41–3.45 (m, 4H), 3.62–3.66
(m, 16H), 5.13–5.15 (m, 2H), 5.29–5.56 (br abs, 10H),
7.22–7.35 (m, 12H), 7.64 (BB0 part of the AA0BB0 system,
J = 8.2 Hz, 4H), 7.67 (BB0 part of the AA0BB0 system, J =
8.2 Hz, 4H), 7.69 (BB0 part of the AA0BB0 system,
A mixture of (E,E,E)-1,6,11,16-tetrakis[(4-methylphe-
nyl)sulfonyl]-1,6,11,16-tetraazahexadeca-3,8,13-triene (9),

A. Pla-Quintana et al. / Journal of Organometallic Chemistry 692 (2007) 2997–3004
3003
J = 8.2 Hz, 4H); 13C NMR (50 MHz, CDCl3) 21.4, 44.3,
48.5, 48.6, 48.8, 127.0, 127.1, 127.7, 128.9, 129.2, 129.6,
129.7, 129.8, 136.4, 136.6, 136.8, 143.3, 143.5, 143.6; ESI-
MS (m/z) 1287 [M+H]+, 1304 [M+NH4]+, 1309
[M+Na]+, 1325 [M+K]+. Anal. Calc. for C62H74N6O12S6
(1287.7): C, 57.83; H, 5.79; N, 6.53; S, 14.91. Found: C,
57.68; H, 5.96; N, 6.49; S, 14.65%.
nedipalladium(0) (5), as a colourless solid (0.11 g, 63%
yield); m.p. 190–191 ꢁC (dec); IR (ATR) 2921, 1331,
1158 cmꢁ1 1H NMR (500.13 MHz, CDCl3): 1.37 (dd,
;
J = 10.8 and 14.1 Hz, 4H), 1.61 (m, 4H), 2.42 (s, 12H),
2.52 (s, 6H), 3.41 (t, J = 11.2 Hz, 4H), 3.50 (dd, J = 10.8
and 14.3 Hz, 4H), 3.98 (m, 4H), 4.05 (m, 4H), 4.06 (m,
4H), 4.31 (d, J = 14.1 Hz, 4H), 4.62 (d, J = 13.8 Hz, 4H),
7.30 (AA0 part of the AA0BB0 system, J = 8.2 Hz, 8H),
7.45 (AA0 part of the AA0BB0 system, J = 8.2 Hz, 4H),
7.59 (BB0 part of the AA0BB0 system, J = 8.2 Hz, 8H),
7.72 (BB0 part of the AA0BB0 system, J = 8.2 Hz, 4H);
13C NMR (125 MHz, CDCl3): 21.5, 21.6, 48.0, 48.3, 50.6,
74.2, 80.1, 85.4, 127.1, 127.2, 129.8, 130.1, 134.4, 138.6,
143.6, 143.9; ESI-MS (m/z) 1575 [M+Na]+. Anal. Calc.
for C66H78N6O12S6 (1552.5): C, 51.06; H, 5.06; N, 5.41.
Found: C, 50.95; H, 5.43; N, 5.22%.
Crystal structure determination: Colourless crystals of 5
were grown by slow evaporation at room temperature in
dichloromethane. The measured crystals were prepared
under inert conditions immersed in perfluoropolyether as
protecting oil for manipulation.
Data collection: Measurements were made on a Bruker–
Nonius diffractometer equipped with an APPEX 2 4K
CCD area detector, an FR591 rotating anode with Mo
Ka radiation, Montel mirrors as monochromator and a
Kryoflex low temperature device (T = 100 K). Full-sphere
data collection was used with x and u scans. Programs
used: data collection APEX2 V. 1.0-22 (Bruker–Nonius
2004), data reduction SAINT+ Version 6.22 (Bruker–Nonius
2001) and absorption correction SADABS V. 2.10 (2003).
Structure solution and refinement: SHELXTL Version 6.10
(Sheldrick, 2000) was used.
3.6. Preparation of (E,E,E,E,E,E)-1,6,11,16,21,26-
hexakis[(4-methylphenyl)sulfonyl]-1,6,11,16,21,26-
hexaazacyclotriaconta-3,8,13,18,23,28-hexaene (13)
A
mixture of (E,E,E,E,E)-1,6,11,16,21,26-hexakis
[(4-methylphenyl)sulfonyl]-1,6,11,16,21,26-hexaazahexa-
cosa-3,8,13,18,23-pentaene (11), (1.51 g, 1.2 mmol), (E)-
1,4-dibromobutene (12), (0.26 g, 1.2 mmol), and anhydrous
potassium carbonate (1.09 g, 7.9 mmol) in acetonitrile
(130 mL) was refluxed for 21 h (TLC monitoring) in a
250 mL round-bottomed flask equipped with magnetic stir-
ring and a condenser. After cooling to room temperature,
the salts were filtered off and the filtrate was evaporated.
The residue was purified first by column chromatography
through silica gel with mixtures of hexanes–dichlorometh-
ane–ethyl acetate of increasing polarity as the eluent (from
7:2:1 to 2:5:3) and secondly by crystallization from mix-
tures of hexanes–dichloromethane–ethyl acetate to afford
(E,E,E,E,E,E)-1,6,11,16,21,26-hexakis[(4-methylphenyl)sul-
fonyl] -1,6,11,16,21,26 -hexaazacyclotriaconta -3,8,13,18,23,
28-hexaene (13), as a colourless solid (0.92 g, 59% yield);
m.p. 182–185 ꢁC; IR (ATR) 2920, 1332, 1157 cmꢁ1 1H
;
NMR (200 MHz, CDCl3) 2.43 (s, 18H), 3.64 (broad s,
24H), 5.45 (broad s, 12H), 7.30 (AA0 part of the AA0BB0
system, J = 8.2 Hz, 12H), 7.64 (BB0 part of the AA0BB0
system, J = 8.2 Hz, 12H); 13C NMR (50 MHz, CDCl3)
21.5, 48.8, 127.2, 129.2, 129.8, 136.3, 143.5; ESI-MS
(m/z) 1339 [M+H]+, 1356 [M+NH4]+, 1377 [M+K]+.
Anal. Calc. for C66H78N6O12S6 (1339.7): C, 59.17; H,
5.87; N, 6.27; S, 14.36. Found: C, 59.02; H, 6.20; N, 6.20;
S, 14.10.
Acknowledgements
The financial support from Ministry of Education and
Science (MEC) of Spain (Projects CTQ2005-04968 and
BQU2003-01677) and Generalitat de Catalunya (Project
2005SGR00305) is gratefully acknowledged.
3.7. Preparation of (E,E,E,E,E,E)-1,6,11,16,21,26-hexakis-
[(4-methylphenyl)sulfonyl]-1,6,11,16,21,26-hexaaza-
cyclotriaconta-3,8,13,18,23,28-hexaenedipalladium(0) (5)
Appendix A. Supplementary material
CCDC 637301 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free
of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.jorganchem.
2007.03.025.
A mixture of (E,E,E,E,E,E)-1,6,11,16,21,26-hexakis[(4-
methylphenyl)sulfonyl]-1,6,11,16,21,26-hexaazacyclotriaconta-
3,8,13,18,23,28-hexaene (13), (0.15 g, 0.1 mmol) and bis
(dibenzylideneacetone)palladium(0) (0.13 g, 0.2 mmol) in
acetonitrile (8 mL) was stirred at room temperature for
8 h (TLC monitoring). After removing the solvent, the res-
idue was purified first by column chromatography through
silica gel with mixtures of hexanes–dichloromethane–ethyl
acetate of increasing polarity as the eluent (from 7:2:1 to
0:3:7) and secondly by crystallization from mixtures of hex-
anes–dichloromethane–ethyl acetate to afford (E,E,E,E,
E,E)-1,6,11,16,21,26-hexakis[(4-methylphenyl)sulfonyl]-1,
6,11,16,21,26-hexaazacyclotriaconta-3,8,13,18,23,28-hexae-
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