Self-assembly of Pd2L2 Metallacycles Owning Diversely Functionalized Racemic Ligands

Article abstract of DOI:10.1021/acs.inorgchem.5b02650

We present herein the efficient palladium(II)-directed self-assembly in water of a series of nine new diversely functionalized metallacycles, owning hydroxy/alkoxycarbonyl/azidoalkyl exo pendant groups attached to ditopic N-monoalkyl/aryl-4,4′-bipyridinium/2,7-diazapyrenium ligands. The highly convergent and versatile synthetic route for the ligands uses the Zincke reaction between (dinitrophenyl)bipyridinium/diazapyrenium salts and racemic amines as the key step. The stereochemical outcome of the self-assembly of the Pd₂L₂ species is discussed on the basis of density functional theory quantum-chemical calculations.

Full text of DOI:10.1021/acs.inorgchem.5b02650

Article
pubs.acs.org/IC
Self-assembly of Pd L Metallacycles Owning Diversely
2
2
Functionalized Racemic Ligands
†
†
†
†
‡
Tamara Rama, Cristina Alvarino, Olaya Domarco, Carlos Platas-Iglesias, Víctor Blanco,
̃
,†
,†
†
Marcos D. García,* Carlos Peinador,* and Jose
́
M. Quintela
†
Departamento de Química Fundamental and Centro de Investigacion
a, E-15071 A Coruna, Spain
Departamento de Química Organica, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada,
Spain
́
s Científicas Avanzadas, Facultade de Ciencias, Universidade da
Corun
‡
̃
̃
́
*
S Supporting Information
ABSTRACT: We present herein the efficient palladium(II)-directed
self-assembly in water of a series of nine new diversely functionalized
metallacycles, owning hydroxy/alkoxycarbonyl/azidoalkyl exo pendant
groups attached to ditopic N-monoalkyl/aryl-4,4′-bipyridinium/2,7-
diazapyrenium ligands. The highly convergent and versatile synthetic
route for the ligands uses the Zincke reaction between (dinitrophenyl)-
bipyridinium/diazapyrenium salts and racemic amines as the key step.
The stereochemical outcome of the self-assembly of the Pd L species is
2
2
discussed on the basis of density functional theory quantum-chemical
calculations.
1
9
INTRODUCTION
In recent times, coordination-driven self-assembly has been
established as an outstanding tool for the preparation of 2D
building blocks for interlocked architectures, we decided to
■
1
pursue the synthesis of a new series of exo-functionalized Pd2L
metallacyclophanes of type M (Scheme 1), trying to implement
2
2
metallacycles and 3D metallacages. The topology of these
Scheme 1. Planned Self-assembly of Exo-Functionalized
Metallocycles of Type M in Water
discrete self-assembled coordination complexes (SCCs) can be
easily adjusted by an appropriate selection of ligands and metal
centers, resulting in a large number of cases into hollow
supramolecular receptors with shapes and sizes modified
2
virtually at will. This modularity of the approach has led to
5
an explosion in the chemistry of SCCs as host molecules and,
6
as a result, in the development of molecular flasks and cavity-
7
controlled catalysis. Furthermore, SCCs can show as well
2
,3
2,4
interesting photochemical and electronic features, opening
the door for a vast array of potential applications in
8
9
10
electrochemistry, biomedicine, materials science, etc.
Nevertheless, the a la carte synthesis of SCCs, owning
completely predesigned and fine-tuned structural and func-
̀
1
1
tional features, is still a distant goal; in part because of the
potential interference on the self-assembly processes between
complexly functionalized ligands with multiple coordination
sites. In this context, the exo functionalization of metallacyclic
SCCs increases the applicability of self-assembled structures
beyond the cavity of the receptor. Several examples of these
a flexible derivatization protocol for the future pre- and
postassembly modification of the supramolecules. As shown, we
intended to self-assemble these metallacycles from palladium-
(II) metal centers and N-monoalkyl/aryl-4,4′-bipyridinium/2,7-
diazapyrenium ligands of type (±)-L, owning diverse
functionalization in an α position to the quaternized nitrogen
atom. To achieve this target, the synthetic plan intended to use
12
types of SCCs have recently been reported, showing the
benefits of functionalization of these supramolecular receptors
in the development of diverse functional systems such as, for
14
1
3
example, transmembrane nanopores, metallohydrogels,
15
16
supramolecular polymers, or vapor sensors.
Following our ongoing interest in the development of new
Received: November 19, 2015
1
7
18
metallacycles and their use as molecular receptors and
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.5b02650
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Inorganic Chemistry
Article
Scheme 2. Synthesis of Racemic Amines of Type A
2
0
as the key step the Zincke reaction
between the
Table 1. Synthesis of Ligands L by the Zincke Reaction
(
dinitrophenyl)bipyridinium/diazapyrenium salts DNPBP/
2
1
DNPDZ and racemic amines of type (±)-A. The utilization
of DNPBP or DNPDZ would allow for modification of the π-
deficient character of the designed metallacyclic receptors,
while the use of different anilines and benzylamines would pave
the way for modulation of the length of the supramolecules and
their exo functionalization.
It should be noted that our intended synthetic route has been
designed to implement two highly desirable objectives: first, the
self-assembly of ligands in aqueous media would be guaranteed
by the use of appropriate N-monoalkylbipyridinium-based
nitrates as ligands and, second, the inclusion of pendants with
organic functionalities in an sp -hybridized carbon opens the
door for the introduction of chirality to the self-assembled
supramolecules.
a
b
c
(
±)-A
(±)-L (G)
9 (OH)
reaction conditions
yield
yield
DNPDZ
DNPDZ
DNPDZ
DNPDZ
DNPBP
DNPBP
DNPBP
DNPBP
DNPBP
3
4
6
8
3
4
6
7
8
1.5 equiv, 12 h, rt
1.4 equiv, 12 h, rt
70
68
56
72
70
64
78
80
81
80
50
78
74
43
29
69
57
54
10 (N3)
3
11 (CO Et)
1.3 equiv, 24 h, ref
1.3 equiv, 24 h, ref
1.5 equiv, 2 h, rt
1.4 equiv, 3 h, rt
1.3 equiv, 3 h, ref
1.3 equiv, 3 h, ref
1.3 equiv, 3 h, ref
2
12 (N3)
13 (OH)
14 (N3)
15 (CO Et)
2
RESULTS AND DISCUSSION
■
16 (OH)
17 (N3)
The benzylic amines of type A [(±)-2−4; Scheme 2] were
efficiently synthesized starting from isonicotinonitrile (1). By a
slight modification of the protocol reported by Fu
the racemic aminoester (±)-2 was prepared by the decarbox-
ylative Blaise reaction of 1 followed by palladium/carbon-
catalyzed reduction of the resultant enamine. Reaction of the
a
b
Equivalents of the amine (±)-A, reaction time, temperature. Yields
for the Zincke reaction. Yields for the conversion of (±)-L·Cl into
(±)-L·NO3.
22
c
̈
lo
̈
p et al.,
ester group in (±)-2 with LiAlH yielded the amino alcohol
compared with the anilines 6−8, ligands 9−12 were obtained in
shorter times and milder conditions than 13−17.
4
(
±)-3, which was further transformed into the azide (±)-4 by
17
treatment with thionyl chloride followed by S 2 nucleophilic
According to our previously reported methodology and in
order to avoid the potential coordination of the chloride anions
to palladium(II) during the self-assembly of metallacycles of
type M, we transformed the ligands into their corresponding
noncoordinating water-soluble nitrate salts by anion metathesis.
As shown in Table 1, these reaction sequences proceeded in
overall moderate to good yields.
N
substitution with NaN in N,N-dimethylformamide (DMF).
3
In a similar fashion, the synthesis of anilines of type A
[
(±)-6−8; Scheme 2] was achieved in good yields starting from
-(4-nitrobenzyl)pyridine (5). Michael addition of 5, using
ethyl acrylate as the acceptor and NaH as the base in dry
4
23
tetrahydrofuran (THF), followed by reduction of the nitro
group by catalytic hydrogenation, yielded the expected racemic
aminoester (±)-6. The amino alcohol (±)-7 and the amino-
azide (±)-8 were prepared using the same synthetic protocol as
that described for (±)-2−4 (vide supra).
Aiming to evaluate the ability of 9−17·NO to form
3
metallacyclic species in water, we proceeded to explore the
palladium(II)-directed self-assembly by recording the corre-
1
13
sponding H and C NMR spectra after mixing stock solutions
−
The results regarding the reaction between the DNPBP·Cl /
of the ligands in D O with equimolar amounts of (en)Pd-
2
−
DNPDZ·Cl salts and amines (±)-3, (±)-4, and (±)-6−8 are
(NO3)2 (see the scheme in Table 2). As shown, the
24
compiled in Table 1. The expected N-monoalkyl/aryl-4,4′-
bipyridinium/2,7-diazapyrenium ligands 9−17 were obtained in
good yields as their chloride salts. In general, a slight excess of
the amine is required for the reactions to complete, in good
agreement with the reversible nature of the reaction proceeding
corresponding metallacycles 18−26·6NO appear as the sole
3
products of the self-assembly in the concentration window of
26
5−0.1 mM, in good agreement with our previous results with
17−19
nonfunctionalized analogues.
These results confirm that
the extra functional groups installed on the ligands (namely,
hydroxyl, alkoxycarbonyl, or azido substituents) do not
interfere in the self-assembly process.
25
through an ANRORC mechanism. As expected, according to
the increased nucleophilicity of the aliphatic amines 2−4
B
DOI: 10.1021/acs.inorgchem.5b02650
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Inorganic Chemistry
Article
1
Table 2. H Chemical Shifts Induced by the Self-assembly of Metallacycles 18−26 in Water
a
Δδ (ppm)
(
±)-L
M (G)
Ha
Hb
Hc
Hd
He
Hf
Hg
Hh
9
18 (OH)
19 (N3)
0.35
0.36
0.29
0.33
0.22
0.22
0.12
0.1
0.24
0.24
−0.04
0.04
0.22
0.22
0.14
0.11
0.12
−0.11
−0.13
−0.22
−0.23
−0.09
−0.09
−0.19
−0.19
−0.19
−0.24
−0.27
0.03
−0.18
−0.19
0.01
0.19
0.16
0.38
0.31
0.11
0.1
10
11
12
13
14
15
16
17
20 (CO Et)
−0.38
−0.38
−0.44
−0.45
2
21 (N3)
22 (OH)
23 (N3)
−0.02
−0.27
−0.27
−0.15
−0.16
−0.15
−0.05
−0.09
−0.09
−0.07
−0.06
−0.06
24 (CO Et)
−0.14
−0.16
−0.16
−0.21
−0.2
−0.2
0.13
0.12
0.13
2
25 (OH)
26 (N3)
0.11
a
1
H NMR (500 MHz, D O) chemical shifts of representative proton nuclei of each metallacycle 18−26 compared with the corresponding free ligand
2
(±)-9−17·NO .
3
1
D and 2D NMR experiments allowed us to obtain
additional structural information about the supramolecules
formed in solution (Table 2). In general, protons in positions α
and β with respect to the coordinating nitrogen atoms (i.e., Ha/
H and H ) are substantially deshielded upon coordination of
b
h
the ligands to the metal centers. Conversely, protons on the
long side of the rectangular structure are shielded compared
with those of the free ligands, which is a typical consequence of
the formation of a π-deficient hydrophobic cavity within these
types of SSCs. In order to show the potential of the synthetic
approach for the construction of other metal-containing
supramolecules and in order to characterize more accurately
the obtained Pd L metallacyclic structures, we decided to use
2
2
27
our previously reported microwave-assisted protocol for the
synthesis of a platinum(II) analogue of metallacycle 24.
Therefore, the Pt L metallacycle 27 was synthesized, isolated,
1
Figure 1. Partial H NMR (500 MHz, D
O) spectra of 13·NO (top)
3
2
2
2
and 22·6NO (bottom).
and characterized as the corresponding nitrate and hexafluor-
3
1
13
ophosphate salts. The H and C NMR spectra of 27 show
chemical shifts very similar to those corresponding to the
palladium metallacycle. Moreover, mass spectrometry supports
the formation of dinuclear species, with characteristic peaks
resulting from the loss of between two and five hexafluor-
ophosphate anions.
depicted in Scheme 3 for (±)-13, the self-assembly around two
palladium(II) centers of two ligands owning the same absolute
configuration on the asymmetric carbon [(R)-13 + (R)-13 or
(
S)-13 + (S)-13] would result in formation of the enantiomeric
pair syn-(R,R)-22/syn-(S,S)-22. On the contrary, if the two
ligands involved have different stereochemistries [(R)-14 + (S)-
14 or (S)-14 + (R)-14], these combinations would result in the
meso compound anti-(R,S)-22.
1
Figure 1 presents a comparison between the partial H NMR
spectra (500 MHz, D O) obtained for ligand 13 and its
2
corresponding self-assembled metallacycle 22. Apart from the
NMR spectroscopic characteristics commented on above for
the aromatic protons of the supramolecule, it is interesting to
note the splitting of one of the doublets of the bipyridinium
Because of the dynamic nature of the self-assembly process,
the interconversion between isomers syn/anti-22 can be easily
achieved by reorganization of the constituents, resulting in
different populations of the species in solution on the basis of
their relative energies. In order to clarify this issue, we
performed density functional theory (DFT) calculations in
aqueous solution at the M06/6-31G(d,p) level (using the
LanL2DZ effective core potential and associated basis set for
palladium; see the Supporting Information for details). Full
geometry optimization of metallacycle 22 provided the
expected syn and anti isomers as minimum-energy conforma-
system (H ) into two doublets of the same intensity. The
f
1
13
splitting of certain H and C NMR signals is also observed for
other metallacycles reported in this work (see the Supporting
Information). We attribute this effect to the presence of
isomeric metallacycles in solution having nearly identical
populations and very similar chemical shifts (vide infra).
Indeed, the use of the racemic ligands (±)-9−17 for the self-
assembly process has a curious stereochemical outcome. As
C
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Inorganic Chemistry
Article
Milli-Q water was purified with a Millipore Gradient A10 apparatus.
Merck 60 F254 foils were used for thin-layer chromatography (TLC),
and Merck 60 (230−400 mesh) silica gel was used for flash
chromatography. 1H and C NMR spectra were recorded on a
Bruker Avance 300 or a Bruker Avance 500 spectrometer equipped
Scheme 3. Representation of the Stereochemical Outcome of
the Self-assembly for Metallacycle 22·6NO and Calculated
3
Structures for Syn (top) and Anti (bottom) Stereoisomers
13
1
13
with a dual cryoprobe for H and C, using the deuterated solvent as a
lock and the residual protiated solvent as an internal standard. Mass
spectrometry (MS) experiments were carried out in a LCQ-q-TOF
Applied Biosystems QSTAR Elite spectrometer for low- and high-
resolution electrospray ionization (ESI). Microwave-assisted reactions
were carried out in an Anton Paar Monowave 300 reactor in a 30 mL
sealed reaction vial. The reaction mixture temperature was monitored
via a built-in IR sensor. Microanalyses for carbon, hydrogen, and
nitrogen were performed by the elemental analyses general service of
̃
Universidade da Coruna.
Synthesis of Amines of Type A. (±)-Ethyl 3-Amino-3-(pyridin-
-yl)propanoate (2). Compound (Z)-1a was prepared according to
4
2
0
the literature procedure and showed spectroscopic data in good
1
agreement with those reported. H NMR (300 MHz, CDCl ): δ 8.74
3
(
2H, d, J = 6.2 Hz), 7.49 (2H, d, J = 6.3 Hz), 5.02 (1H, s), 4.19 (2H, q,
tions (see the inset in Scheme 3), which possess slightly
distorted C2v and C2h symmetries, respectively. The electronic
energy difference between the syn and anti isomers is only
J = 7.1 Hz), 1.30 (3H, t, J = 7.1 Hz).
Subsequent reduction of the double bond in (Z)-1a was achieved by
20
̈
̈
a slight modification of the method reported by Fulop et al. Here,
0
.106 kJ/mol, in good agreement with the NMR data, which
palladium/carbon (1.5 g, 1% w/w) was added to a degassed solution
of compound (Z)-1a (4.5 mmol, 0.865 g) in ethanol (EtOH; 30 mL).
The mixture was hydrogenated at atmospheric pressure and room
temperature for 24 h. The solution was filtered to remove the catalyst
and concentrated under vacuum. The resulting residue was subjected
show that the isomeric species have virtually identical
populations in solution at room temperature. Nonetheless, it
should be noted that the similarity in the energies of the
isomeric metallacycles has more profound implications on the
self-assembly itself: while the two isomers of the enantiomeric
pair syn-22 can, in principle, be obtained as the sole products of
the self-assembly by using enantiomerically pure ligands, the
meso isomer anti-22 cannot.
to flash chromatography [SiO ; 9:1 ethyl acetate (EtOAc)/methanol
(
data coincident with that reported. H NMR (CDCl , 500 MHz): δ
8
and 5.1 Hz), 4.14 (2H, q, J = 7.1 Hz), 2.74−2.54 (2H, m), 1.23 (3H, t,
J = 7.1 Hz). ESI-MS. Calcd for [M + H] : m/z 195.1128. Found: m/z
195.1146.
2
MeOH)] to yield (±)-2 as a yellow oil (94%) and with spectroscopic
1
3
.57 (2H, d, J = 4.6 Hz), 7.31 (2H, d, J = 4.6 Hz), 4.41 (1H, dd, J = 8.4
+
CONCLUSIONS
■
In summary, we have developed a highly versatile and efficient
synthetic route for the preparation of racemic bipyridinium-
based ligands and their corresponding Pd L metallacycles. This
(±)-3-Amino-3-(4-pyridyl)-1-propanol (3). The β-amino ester
(±)-2 (2.5 mmol, 0.49 g) was added to a suspension of LiAlH
THF (5 mL) under an argon atmosphere and the mixture stirred for
4 h at room temperature. The reaction was quenched with a mixture
in
4
2
2
2
approach allows not only modification of the size and shape of
the metallacycles but also modulation of their exo functional-
ization. Because the derivatization has been implemented in a
of THF/ice, the resulting suspension filtered, and the solvent removed
under vacuum to yield a yellow solid residue. This was subjected to
flash chromatography (SiO ; 1:1 EtOAc/MeOH), affording (±)-2 as a
yellow oil (45%). H NMR (CDCl , 500 MHz): δ 8.57 (2H, d, J = 4.6
3
2
sp -hybridized carbon, the reported synthetic approach
1
3
implicitly opens the door for the construction of chiral
metallacyclic SCCs. Remarkably, the introduction of azide,
alcohol, and ester functionalities on the ligands was shown to
not interfere with their ability to self-assemble into Pd2L2
metallacycles. Furthermore, the self-assembly of the Pt2L2
analogue 27 has also been achieved, proving that metal
complexes, other than palladium(II), could be employed for the
synthesis of functionalized SCCs using our ligands. Crucially,
the chameleonic nature of the N-monoalkylbipyridinium-based
cations used as ligands, with their solubility on aqueous and
organic media being controlled by the corresponding counter-
ion, has allowed the self-assembly of the exo-functionalized
metallacycles in water, amplifying in this manner the potential
applications of these SCCs.
Hz), 7.24 (2H, d, J = 4.6 Hz), 4.16 (1H, dd, J = 8.3, 4.7 Hz), 3.85−
+
3
.76 (2H, m), 1.96−1.81 (2H, m). ESI-MS. Calcd for [M + H] : m/z
153.1022. Found: m/z 153.1031.
(±)-3-Azido-1-(pyridin-4-yl)propan-1-amine (4). Compound
(±)-3 (380 mg, 2.49 mmol) was dissolved in a minimum amount of
CHCl and the solution cooled in an ice bath at 0 °C. SOCl (10
3
2
equiv) was then added dropwise for 15 min and the reaction
monitored by TLC. Once completed, water (15 mL) was added and
the pH adjusted to 8−9 by the addition of KOH (50%). The organic
layer was separated and the aqueous layer extracted with CHCl (2 ×
3
3
0 mL). The solvent was then evaporated under vacuum to yield
(
±)-3a as a brown oil (70%), which was used without further
1
purification. H NMR (CDCl , 500 MHz): δ 8.68 (2H, d, J = 4.6 Hz),
3
7.29 (2H, d, J = 4.6 Hz), 4.21 (1H, t, J = 6.9 Hz), 3.70−3.62 (1H, m),
1
3
3.53−3.38 (1H, m), 2.16−2.04 (2H, m). C NMR (CD OD, 125
3
Prospectively, the results reported herein open the door for
the versatile pre and postassembly modification of Pd L and
MHz): δ 159.55 (CH), 122.38 (CH), 51.97 (CH), 40.15 (CH ), 38.02
2
(
CH2).
2
2
In order to introduce the azide functional group, (±)-3a (265.9 mg,
1.55 mmol) was dissolved in a minimum amount of DMF and NaN3
5 equiv) added to the solution, which was heated at 50 °C overnight.
Pt L metallacycles by means of, for instance, copper-catalyzed
2
2
2
8
azide alkyne cycloadditions. Ongoing studies in our
laboratory along these lines are currently underway and will
be reported in due course.
(
Once the reaction was completed (followed by TLC), DMF was
removed and EtOAc (20 mL) and water (10 mL) were added. The
organic layer was separated and the aqueous layer further extracted
with EtOAc (4 × 20 mL). The sum of the organic layers was collected,
EXPERIMENTAL SECTION
General Remarks. Palladium and platinum complexes were
prepared according to literature procedures. All other reagents used
were commercial-grade chemicals from freshly opened containers.
■
2
9
and the solvents were evaporated under vacuum to yield (±)-4 as a
1
brown oil (75%). H NMR (CDCl , 500 MHz): δ 8.57 (2H, d, J = 4.6
3
Hz), 7.26 (2H, d, J = 4.6 Hz), 4.05 (1H, t, J = 6.9 Hz), 3.47−3.38 (1H,
D
DOI: 10.1021/acs.inorgchem.5b02650
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Inorganic Chemistry
Article
1
3
m), 3.33−3.24 (1H, m), 1.94−1.85 (2H, m). C NMR (CDCl , 125
to the obtained a residue and the aqueous phase washed with EtOAc
(3 × 10 mL). The aqueous layer was then concentrated under vacuum
to yield (±)-L·Cl (yields on Table 1)
3
MHz): δ 154.47 (C), 150.29 (CH), 121.68 (CH), 52.78 (CH), 48.53
CH ), 37.89 (CH ). ESI-MS. Calcd for [M + H] : m/z 178.1090.
+
(
2
2
Found: m/z 178.1092.
In order to modulate the solubility of the salts in aqueous or organic
solvents, a series of subsequent metathesis reactions were performed.
First the corresponding chloride salt (±)-L·Cl was dissolved in water
and then KPF6 was added into the solution until no further
precipitation was observed. The obtained yellow solid was filtered
and washed with water to yield (±)-L·PF6.
(
±)-Ethyl 4-(4-Aminophenyl)-4-(pyridin-4-yl)butanoate (6). Com-
pound (±)-5 was prepared according to the literature procedure
showed spectroscopic data in good agreement with those reported. H
28
1
NMR (CDCl , 500 MHz): δ 8.54 (2H, d, J = 6.1 Hz), 8.17 (2H, d, J =
3
8
(
.8 Hz), 7.39 (2H, d, J = 8.8 Hz), 7.14 (2H, d, J = 6.3 Hz), 4.18−3.96
3H, m), 2.48−2.34 (2H, m), 2.26 (2H, t, J = 7.2 Hz), 1.23 (3H, t, J =
In order to obtain the corresponding water-soluble noncoordinating
7
1
1
1
.1 Hz). 13C NMR (CDCl , 75 MHz): δ 172.49 (C), 151.12 (C),
nitrate salt (±)-L·NO , a mixture of ligand as hexafluorophosphate salt
3
3
50.34 (CH), 149.73 (C), 146.98 (C), 128.76 (CH), 124.07 (CH),
23.00 (CH), 60.68 (CH ), 49.46 (CH), 32.01 (CH ), 29.53 (CH ),
4.18 (CH ). ESI-MS. Calcd for [M + H] : m/z 315.1339. Found: m/
and Amberlite CG-400 (300 mg) was suspended in water and stirred
for 24 h at room temperature. The resin was then removed by
filtration and the solvent dried under vacuum to yield (±)-L·Cl. Then,
the ligand as chloride salt was dissolved in water and 1 equiv of AgNO3
added, and this solution was stirred at room temperature for 12 h with
exclusion of light. Finally, the mixture was filtered to remove the AgCl
precipitate formed, and the solvent was evaporated under vacuum to
yield (±)-L·NO3.
2
2
2
+
3
z 315.1353.
(
±)-5a (277.3 mg, 0.882 mmol) was dissolved in EtOH (20 mL)
and palladium/carbon (100 mg, 5% w/w) added to the degassed
solution. The mixture was hydrogenated at atmospheric pressure and
room temperature for 24 h. The solution was filtered to remove the
(±)-9·NO . Hygroscopic brownish solid. 1H NMR (D O, 500
catalyst. The resulting filtrate was purified by column chromatography
SiO ; 8:2 EtOAc/hexane), yielding (±)-6 as a yellow oil (70%). H
NMR (CDCl , 500 MHz): δ 8.46 (2H, d, J = 5.6 Hz), 7.19 (2H, d, J =
.0 Hz), 6.97 (2H, d, J = 8.3 Hz), 6.63 (2H, d, J = 8.5 Hz), 4.10 (2H,
q, J = 7.1 Hz), 3.83 (1H, t, J = 7.5 Hz), 2.35−2.28 (2H, m), 2.28−2.22
2H, m), 1.23 (3H, t, J = 7.1 Hz). 13C NMR (CDCl , 125 MHz): δ
73.36 (C), 155.10 (C), 149.26 (CH), 145.55 (C), 131.77 (CH),
28.96 (CH), 123.42 (CH), 115.58 (CH), 60.62 (CH ), 49.19 (CH),
2.63 (CH ), 30.08 (CH ), 14.34 (CH ). ESI-MS. Calcd for [M +
H] : m/z 285.1597. Found: m/z 285.1605.
±)-4-(4-Aminophenyl)-4-(pyridin-4-yl)butan-1-ol (7). A solution
of (±)-6 (306.5 mg, 1.08 mmol) in dried THF (40 mL) was added
dropwise at 0 °C under an argon atmosphere to a suspension of
LiAlH (2 equiv) in dried THF (10 mL). The resulting mixture was
stirred overnight under an argon atmosphere at room temperature.
The reaction was quenched with a mixture of THF/ice mixture and
stirred for a few hours. The resulting white suspension was filtered and
the obtained solid washed with MeOH. The solvent was removed
under vacuum and purified by column chromatography (SiO ;
EtOAc/MeOH) to yield (±)-7 as a yellow oil (61%). H NMR
CDCl , 500 MHz): δ 8.45 (2H, d, J = 6.1 Hz), 7.14 (2H, d, J = 6.2
Hz), 6.98 (2H, d, J = 8.3 Hz), 6.62 (2H, d, J = 8.5 Hz), 3.77 (1H, t, J =
.9 Hz), 3.64 (2H, t, J = 6.4 Hz), 2.12−2.01 (2H, m), 1.58−1.45 (2H,
m). C NMR (CDCl , 125 MHz): δ 154.85 (C), 149.96 (CH),
45.37 (C), 133.12 (C), 128.92 (CH), 123.38 (CH), 115.61 (CH),
2.75 (CH ), 49.89 (CH), 31.42 (CH ), 31.21 (CH ). ESI-MS. Calcd
for [M + H] : m/z 243.1491. Found: m/z 243.1501.
±)-4-[4-Azido-1-(pyridin-4-yl)butyl]aniline (8). Compound
±)-7a was prepared under the same conditions as those described
above for (±)-3a, yielding (±)-7a as a brown oil (98%). H NMR
CDCl , 500 MHz): δ 8.49 (2H, br s), 7.17 (2H, d, J = 4.5 Hz), 6.98
3
2
1
(
MHz): δ 9.93 (2H, s), 9.65 (2H, s), 8.67 (2H, d, J = 6.4 Hz), 8.60
(2H, d, J = 9.1 Hz), 8.46 (2H, d, J = 9.1 Hz), 7.70 (2H, d, J = 6.4 Hz),
6.78−6.60 (1H, m), 3.82−3.78 (1H, m), 3.60−3.55 (1H, m), 3.12−
2
3
6
2.99 (2H, m). 13C NMR (D O, 125 MHz): δ 149.95 (CH), 146.96
2
(
(CH);, 145.90 (C), 137.41 (CH), 131.11 (CH), 129.42 (C), 128.78
(C), 126.28 (C), 125.95 (CH), 124.18 (C), 122.97 (CH), 72.04
(CH), 57.07 (CH ), 35.16 (CH ).
3
1
1
3
2
2
2
1
2
2
3
(±)-9·PF . Hygroscopic brownish solid. H NMR (CD CN, 500
6
3
+
MHz): δ 9.86 (2H, s), 9.72 (2H, s), 8.71 (2H, d, J = 9.1 Hz), 8.69
(2H, d, J = 6.4 Hz), 8.52 (2H, d, J = 9.1 Hz), 7.53 (2H, d, J = 6.4 Hz),
6.53 (1H, dd, J = 8.6 and 6.7 Hz), 3.73−3.64 (1H, m), 3.45−3.35 (1H,
(
1
3
m), 2.91−2.84 (2H, m). C NMR (CD CN, 125 MHz): δ 151.82
3
4
(CH), 149.31 (CH), 145.79 (C), 138.59 (CH), 132.25 (CH), 130.40
(C), 130.27 (C), 126.95 (CH), 125.04 (C), 123.65 (CH), 73.35
(CH), 57.87 (CH ), 36.57 (CH ). ESI-MS. Calcd for [M − PF ] : m/
z 340.1444. Found: m/z 340.1452. Anal. Calcd C H F N OP: C,
+
2
2
6
22
18
6
3
54.44; H, 3.74; N, 8.66. Found: C, 54.18; H, 3.86; N, 8.35.
1
2
(±)-10·NO . Hygroscopic brownish solid. H NMR (D O, 500
3
2
1
MHz): δ 9.95 (2H, s), 9.66 (2H, s), 8.68 (2H, d, J = 5.3 Hz), 8.63
(2H, d, J = 9.2 Hz), 8.48 (2H, d, J = 9.1 Hz), 7.70 (2H, d, J = 5.3 Hz),
6.68 (1H, dd, J = 9 and 6.4 Hz), 3.64 (1H, m), 3.43 (1H, m), 5.12
(
3
(2H, m). 13C NMR (D O, 125 MHz): δ 150.03 (CH), 147.01 (CH),
7
2
13
3
145.47 (C), 137.28 (CH), 131.21 (CH), 129.50 (C), 128.80 (C),
126.26 (C), 125.92 (CH), 124.10 (C), 122.90 (CH), 72.32 (CH),
47.05 (CH ), 32.09 (CH ).
1
6
2
2
2
2
2
+
1
(±)-10·PF . Hygroscopic brownish solid. H NMR (CD CN, 500
6
3
(
MHz): δ 9.87 (2H, s), 9.71 (2H, s), 8.725 (2H, d, J = 9.1 Hz), 8.69
(2H, d, J = 6.2 Hz), 8.54 (2H, d, J = 9.1 Hz), 7.53 (2H, d, J = 6.2 Hz),
6.40 (1H, dd, J = 8.6−6.8 Hz), 3.54 (1H, dt, J = 13.0−6.2 Hz), 3.40
(
1
1
3
(
(1H, dt, J = 13.1−6.5 Hz), 3.06−2.94 (2H, m). C NMR (CD CN,
3
3
(
3
2H, d, J = 8.3 Hz), 6.63 (2H, d, J = 8.5 Hz), 3.78 (1H, t, J = 7.9 Hz),
125 MHz): δ 151.92 (CH), 149.38 (CH), 145.07 (C), 138.33 (CH),
132.39 (CH), 130.59 (C), 130.36 (C), 129.97 (CH), 126.94 (C),
124.95 (C), 123.56 (CH), 73.56 (CH), 48.04 (CH ), 33.42 (CH ).
ESI-MS. Calcd for [M − PF ] : m/z 365.1509. Found: m/z 365.1508.
Anal. Calcd C H F N P: C, 51.77; H, 3.36; N, 16.47. Found: C,
.53 (2H, t, J = 6.5 Hz), 2.19−2.10 (2H, m), 1.79−1.67 (2H, m).
Compound (±)-8 was prepared under the same conditions as those
2
2
+
described above for (±)-4, yielding (±)-8 as a dark brown oil (86%).
6
1
H NMR (CDCl , 500 MHz): δ 8.48 (2H, d, J = 6.2 Hz), 7.12 (2H, d,
3
22 17
6
6
J = 6.3 Hz), 6.98 (2H, d, J = 8.3 Hz), 6.63 (2H, d, J = 8.5 Hz), 3.78
51.45; H, 3.00; N, 16.40.
(±)-11·NO . Hygroscopic yellowish solid. H NMR (D O, 500
1
(
1H, t, J = 7.8 Hz), 3.29 (2H, t, J = 6.7 Hz), 2.07 (2H, dd, J = 15.8 and
3
2
13
7
1
1
.8 Hz), 1.62−1.48 (2H, m). C (CDCl , 125 MHz): δ 154.38 (C),
MHz): δ 9.89 (2H, s), 9.56 (2H, s), 8.56 (2H, d, J = 9.1 Hz), 8.53
(2H, d, J = 5.4 Hz), 8.45 (2H, d, J = 9.1 Hz), 7.95 (2H, d, J = 8.5 Hz),
7.82 (2H, d, J = 8.5 Hz), 7.60 (2H, d, J = 5.7 Hz),4.37 (1H, t J = 7.8
Hz), 4.11 (2H, q, J = 7.1 Hz), 2.58 (2H, dd, J = 14.7 and 7.3 Hz), 2.47
3
50.07 (CH), 145.34 (C), 132.62 (C), 128.85 (CH), 123.17 (CH),
15.58 (CH), 51.44 (CH ), 49.68 (CH), 32.25 (CH ), 27.45 (CH ).
2
2
2
+
ESI-MS. Calcd for [M + H] : m/z 268.1556. Found: m/z 268.1556.
Synthesis of Ligands 9−17. General Synthetic Procedure. The
(2H, t, J = 7.2 Hz), 1.25 (3H, t, J = 7.1 Hz). 13C NMR (D O, 125
2
(
dinitrophenyl)pyridinium salt (DNPBZ·Cl or DNPBP·Cl) was
MHz): δ 175.90 (C), 155.34 (C), 147.68 (CH), 146.85 (CH), 146.01
(C), 142.37 (C), 138.01 (CH), 131.10 (CH), 130.36 (CH), 128.63
(C), 127.86 (C), 126.08 (C), 126.01 (CH), 125.22 (CH), 124.26
(CH), 123.79 (C), 61.87 (CH ), 49.17 (CH), 32.32 (CH ), 28.89
dissolved in EtOH, and the corresponding amine of type (±)-A was
added in the proper ratio and stirred in the reaction conditions
specified in Table 1. After the solution was cooled, the solvent was
removed under vacuum to leave a solid residue, which was subjected to
flash chromatography [SiO ; 4:1:1 CH CN/NaCl(aq) (0.6 M)/
2
2
(CH ), 13.22 (CH ).
2
3
1
(±)-11·PF . Hygroscopic yellowish solid. H NMR (CD CN, 500
2
3
6
3
MeOH]. The ligand-containing fractions were combined, and the
solvent was removed under vacuum. Water (20 mL) was then added
MHz): δ 9.92 (2H, s), 9.79 (2H, s), 9.78 (2H, d, J = 9.1 Hz), 8.65
(2H, d, J = 6.9 Hz), 8.61 (2H, d, J = 9.0 Hz), 8.00 (2H, d, J = 6.9 Hz),
E
DOI: 10.1021/acs.inorgchem.5b02650
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
1
7
.92 (2H, d, J = 8.6 Hz). 7.78 (2H, d, J = 8.6 Hz), 4.59 (1H, t, J = 7.9
(±)-15·NO . Hygroscopic yellow waxy solid. H NMR (D O, 500
3 2
Hz), 4.11 (2H, q, J = 7.1 Hz), 2.59−2.50 (2H, m), 2.35 (2H, t, J = 7.4
MHz): δ 9.17 (2H, d, J = 7.1 Hz), 8.81 (2H, d, J = 6.3 Hz), 8.56 (2H,
d, J = 7.0 Hz), 8.46 (2H, d, J = 6.2 Hz), 7.99 (2H, d, J = 6.3 Hz), 7.76
(2H, d, J = 8.7 Hz), 7.71 (2H, d, J = 8.7 Hz), 7.46 (2H, d, J = 6.2 Hz),
4.26 (1H, t, J = 7.8 Hz), 4.06 (2H, q, J = 7.2 Hz), 2.52 (2H, dd, J =
Hz), 1.23 (3H, t, J = 7.1 Hz). 13C NMR (CD CN, 125 MHz): δ
3
1
1
1
5
73.14 (C), 149.45 (CH), 145.31 (C), 144.15 (C), 143.10 (CH),
39.28 (CH), 132.67 (CH), 131.50 (CH), 130.04 (C), 129.81 (C),
27.65 (CH), 127.05 (C), 126.90 (CH), 125.06 (C), 61.43 (CH2),
0.38 (CH), 32.49 (CH ), 30.16 (CH ), 14.51 (CH ). ESI-MS. Calcd
1
3
15.5 and 8.3 Hz), 2.42 (2H, t, J = 7.1 Hz), 1.22 (3H, t, J = 7.2 Hz).
C
NMR (D O, 125 MHz): δ 174.94 (C), 154.62 (C), 153.62 (C),
2
2
3
2
+
for [M − PF ] : m/z 472.2019. Found: m/z 472.2023. Anal. Calcd
C H F N O P: C, 60.29; H, 4.24; N, 6.80. Found: C, 60.16; H, 4.20;
150.02 (CH), 148.88 (CH), 146.37 (C), 144.56 (CH), 142.32 (C),
141.06 (C), 130.07 (CH), 125.95 (CH), 124.32 (CH), 123.74 (CH),
6
3
1
26
6
3
2
N, 6.57.
122.52 (CH), 61.74 (CH
13.20 (CH ).
2
), 48.97 (CH), 32.31 (CH ), 28.81 (CH),
2
(
±)-12·NO . Hygroscopic yellowish solid. 1H NMR (D O, 500
3
3
2
1
(
±)-15·PF . Hygroscopic yellow waxy solid. H NMR (300 MHz,
MHz): δ 9.90 (2H, s), 9.63 (2H, s), 8.61 (2H, d, J = 9.1 Hz), 8.52−
.46 (4H, m), 7.93 (2H, d, J = 8.5 Hz), 7.82 (2H, d, J = 8.6 Hz), 7.52
2H, d, J = 6.1 Hz), 4.33 (1H, t, J = 8.0 Hz), 3.42 (2H, t, J = 6.7 Hz),
6
CD CN): δ 9.00 (2H, d, J = 7.2 Hz), 8.90 (2H, d, J = 6.2 Hz), 8.54
8
3
(2H d, J = 6.1 Hz), 8.48 (2H, d, J = 7.1 Hz), 7.88 (2H, d, J = 4.5 Hz),
(
2
(
(
(
(
1
3
7.70 (4H, d, J = 2.7 Hz), 7.36 (2H, d, J = 5.9 Hz), 4.23 (1H, t, J = 7.8
Hz), 4.10 (2H, q, J = 7.1 Hz), 2.43 (2H, q, J = 7.3 Hz), 2.31 (2H, t, J =
.32 (2H, dd, J = 15.6 and 7.9 Hz), 1.72−1.60 (2H, m). C NMR
2
D O, 125 MHz): δ 154.52 (C), 148.78 (CH), 147.01 (C), 146.91
7
1
1
.2 Hz), 1.26 (3H, t, J = 7.1 Hz). 13C NMR (125 MHz, CD CN): δ
72.52 (C), 154.92 (C), 152.26 (C), 151.25 (CH), 150.03 (CH),
47.17 (C), 144.83 (CH), 140.98 (C), 129.91 (CH), 125.95 (CH),
CH), 142.35 (C), 138.06 (CH), 131.11 (CH), 130.22 (CH), 128.71
C), 126.21 (C), 126.06 (CH), 125.13 (CH), 124.01 (C), 123.83
CH), 50.87 (CH ), 49.28 (CH), 31.01 (CH ), 26.39 (CH ).
3
2
2
2
1
124.75 (CH), 123.17(CH), 121.91 (CH), 60.23 (CH ), 48.99 (CH),
(
±)-12·PF . Hygroscopic beige solid. H NMR (CD CN, 500 MHz):
2
6
3
3
1.90 (CH ), 29.33 (CH ), 13.53 (CH ). ESI-MS. Calcd for [M −
+
δ 9.91 (2H, s), 9.89 (2H, s), 8.82 (2H, d, J = 9.1 Hz), 8.67 (2H, d, J =
2
2
3
PF ] : m/z 424.2020. Found: m/z 424.2019.
9
.1 Hz), 8.64 (2H, br s), 8.03 (2H, d, J = 8.7 Hz), 7.87 (2H, d, J = 8.6
6
1
(
±)-16·NO . Hygroscopic yellow waxy solid. H NMR (D O, 500
Hz), 7.70 (2H, d, J = 6.4 Hz), 3.47−3.41 (2H, m), 2.43−2.35 (2H, m),
3
2
1
3
MHz): δ 9.17 (2H, d, J = 7.0 Hz), 8.82 (2H, d, J = 4.6 Hz), 8.52 (2H,
d, J = 6.9 Hz), 8.47 (2H, s), 7.99 (2H, d, J = 6.3 Hz), 7.75 (2H, d, J =
1
1
1
1
2
.75−1.65 (2H, m). C NMR (CD CN, 125 MHz): δ 149.85 (CH),
3
48.04 (C), 144.32 (C), 139.33 (CH), 133.06 (CH), 131.70 (CH),
30.59 (C), 130.36 (C), 127.56 (C),127.32 (CH), 126.95 (CH),
25.92 (CH), 125.51 (C), 52.32 (CH ), 51.37 (CH), 32.80 (CH ),
8.21 (CH ). ESI-MS. Calcd for [M − PF ] : m/z 455.1978. Found:
m/z 455.1985. Anal. Calcd C H F N P: C, 58.00; H, 3.86; N, 14.00.
8
.7 Hz), 7.71 (2H, d, J = 8.7 Hz), 7.47 (2H, d, J = 4.4 Hz), 4.26 (1H, t,
J = 7.9 Hz), 3.64 (2H, t, J = 6.5 Hz), 2.23 (2H, dd, J = 15.7 and 8.0
Hz), 1.55 (2H, dt, J = 13.4 and 6.5 Hz). C NMR (D
1
1
2
2
13
+
2
O, 125 MHz): δ
54.60 (C), 154.49 (C), 150.05 (CH), 148.85 (CH), 147.29 (C),
44.62 (CH), 142.36 (C), 140.89 (C), 130.05 (CH), 125.94 (CH),
2
6
29
23
6
6
Found: C, 58.06; H, 4.01; N, 14.92.
±)-13·NO . Hygroscopic brown solid. H NMR (500 MHz, D O):
1
124.26 (CH), 122.55 (CH), 61.35 (CH
9.51 (CH2).
2
), 49.35 (CH), 30.15 (CH ),
2
(
3
2
2
δ 9.06 (2H, d, J = 6.9 Hz), 8.70 (2H, d, J = 6.3 Hz), 8.56 (2H, d, J =
.4 Hz), 8.39 (2H, d, J = 6.9 Hz), 7.83 (2H, d, J = 6.3 Hz), 7.49 (2H,
d, J = 6.4 Hz), 6.19 (1H, dd, J = 9.0 and 6.4 Hz), 3.67 (1H, ddd, J =
1
(
±)-16·PF . Hygroscopic yellow waxy solid. H NMR (CD CN, 500
6
3
6
MHz): δ 8.98 (2H, d, J = 7.1 Hz), 8.88 (2H, d, J = 6.2 Hz), 8.51 (2H,
d, J = 5.2 Hz), 8.46 (2H, d, J = 7.1 Hz), 7.82 (2H, d, J = 6.2 Hz),
1
2
1.6, 6.3, and 5.1 Hz), 3.50 (1H, ddd, J = 11.9, 7.2, and 4.8 Hz), 2.82−
7
.69−7.66 (4H, m), 7.36 (2H, d, J = 6.1 Hz), 4.20 (1H, t, J = 7.9 Hz),
.63 (2H, m). 13C NMR (125 MHz, D O): δ 155.10(C), 150.07
2
13
3
.54 (2H, t, J = 6.3 Hz), 2.24−2.15 (2H, m), 1.52−1.39 (2H, m).
C
(
(
(
CH), 149.80 (CH), 145.28 (C), 144.22 (CH), 142.23 (C), 126.59
NMR (CD CN, 125 MHz): δ 155.89 (C), 154.55 (C), 152.30 (CH),
3
CH), 122.83 (CH), 122.47 (CH), 70.57 (CH), 56.99 (CH ), 34.63
2
1
1
5
50.68 (CH), 149.01 (C), 145.85 (CH), 141.94 (C), 130.91 (CH),
26.96 (CH), 125.65 (CH), 124.33 (CH), 122.94 (CH), 62.06 (CH2),
CH2).
(
±)-13·PF . Hygroscopic brown solid. 1H NMR (500 MHz,
6
0.69 (CH), 31.72 (CH ), 31.60 (CH ). ESI-MS. Calcd for [M −
2
2
CDCN ): δ 8.92 (2H, d, J = 7.1 Hz), 8.88 (2H, d, J = 6.2 Hz),
+
3
PF ] : m/z 382.1913. Found: m/z 382.1919.
6
8
.72 (2H, d, J = 6.3 Hz), 8.36 (2H, d, J = 7.0 Hz), 7.82 (2H, d, J = 6.2
1
(
±)-17·NO . Hygroscopic yellow waxy solid. H NMR (D O, 500
3
2
Hz), 7.48 (2H, d, J = 6.7 Hz), 6.17 (1H, dd, J = 9.3 and 6.0 Hz), 3.69
MHz): δ 9.17 (2H, d, J = 7.1 Hz), 8.81 (2H, d, J = 6.3 Hz), 8.56 (2H,
d, J = 7.0 Hz), 8.46 (2H, d, J = 6.2 Hz), 7.99 (2H, d, J = 6.3 Hz), 7.76
1
3
(
1H, m), 3.46 (1H, m), 2.79−2.59 (2H, m). C NMR (125 MHz,
CDCN ): δ 155.19 (C), 151.10 (CH), 150.83 (CH), 144.72 (C),
3
(
4
2H, d, J = 8.8 Hz), 7.72 (2H, d, J = 8.7 Hz), 7.48 (2H, d, J = 6.2 Hz),
1
7
44.26 (CH), 141.12 (C), 126.51 (CH), 122.60 (CH), 121.76 (CH),
.29 (1H, t, J = 7.9 Hz), 3.38 (2H, t, J = 6.7 Hz), 2.28 (2H, dd, J = 15.7
0.80 (CH), 56.79 (CH ), 34.96 (CH ). ESI-MS. Calcd for [M −
13
2
2
and 7.9 Hz), 1.61 (2H, dq, J = 12.9 and 6.5 Hz). C NMR (D O, 125
2
+
PF ] : m/z 292.1444. Found: m/z 292.1443. Anal. Calcd
6
MHz): δ 154.60 (C), 154.30 (C), 150.03 (CH), 148.89 (CH), 147.10
(C), 144.61 (CH), 142.39 (C), 140.95 (C), 130.02 (CH), 125.96
C H F N OP: C, 49.44; H, 4.15; N, 9.61. Found: C, 49.30; H,
1
8
18
6
3
4
.01; N, 9.73.
±)-14·NO . Hygroscopic yellow solid. H NMR (D O, 500 MHz):
(
CH), 124.32 (CH), 123.76 (CH), 122.54 (CH), 50.83 (CH ), 49.22
2
1
(
3
2
(CH), 30.94 (CH ), 26.34 (CH ).
2 2
δ 9.16 (2H, d, J = 6.8 Hz), 8.79 (2H, d, J = 6.2 Hz), 8.66 (2H, d, J =
1
(
±)-17·PF . Hygroscopic yellow waxy solid. H NMR (CD CN, 500
6 3
6
.2 Hz), 8.50 (2H, d, J = 6.6 Hz), 7.92 (2H, d, J = 6.3 Hz), 7.59−7.51
MHz): δ 8.97 (2H, d, J = 7.1 Hz), 8.88 (2H, d, J = 6.2 Hz), 8.52 (2H,
d, J = 6.1 Hz), 8.46 (2H, d, J = 7.1 Hz), 7.86 (2H, d, J = 6.2 Hz),
(
3
(
(
(
2H, m), 6.26 (1H, dd, J = 8.6 and 6.7 Hz), 3.63−3.55 (1H, m), 3.50−
13
.40 (1H, m), 2.97−2.89 (1H, m), 2.88−2.79 (1H, m). C NMR
7
.70−7.65 (4H, m), 7.35 (2H, d, J = 6.2 Hz), 4.19 (1H, t, J = 7.9 Hz),
13
D O, 125 MHz): δ 155.27 (C), 150.03 (CH), 149.90 (CH), 144.80
2
3.37 (2H, t, J = 6.4 Hz), 2.27−2.18 (2H, m), 1.62−1.48 (2H, m). C
NMR (CD CN, 125 MHz): δ 155.95 (C), 153.76 (C), 152.28 (CH),
C), 144.14 (CH), 142.18 (C), 126.74 (CH), 122.81 (CH), 122.48
3
CH), 70.85 (CH), 46.92 (CH ), 31.63 (CH ), 31.50 (CH ).
2
2
2
150.98 (CH), 148.66 (C), 145.86 (CH), 141.96 (C), 141.90 (C),
130.84 (CH), 126.95 (CH), 125.72 (CH), 124.17 (CH), 122.92
(CH), 51.81 (CH ), 50.43 (CH), 32.28 (CH ), 21.84 (CH ). ESI-MS.
1
(
±)-14·PF . Hygroscopic yellow solid. H NMR (CD CN, 500
6
3
MHz): δ 8.89 (2H, d, J = 7.0 Hz), 8.85 (2H, d, J = 6.2 Hz), 8.70 (2H,
d, J = 6.2 Hz), 8.35 (2H, d, J = 7.0 Hz), 7.78 (2H, d, J = 6.2 Hz), 7.43
2
2
2
+
Calcd for [M − PF ] : m/z 407.1978. Found: m/z 407.1981.
6
(
2H, d, J = 6.0 Hz), 6.00 (1H, dd, J = 8.9−6.5 Hz), 3.58−3.47 (1H,
Self-assembly of Metallacycles. General Synthetic Procedure.
Complex (en)Pd(NO ) was added to a suspension of (±)-L·NO in
13
m), 3.47−3.33 (1H, m), 2.83−2.65 (2H, m). C NMR (CD CN, 125
MHz): δ 156.49 (C), 152.20 (CH), 151.98 (CH), 145.14 (CH),
3
3
2
3
D O. Both compounds were mixed in 1:1 stoichiometry with a final
2
1
7
44.56 (C), 141.86 (C), 127.76 (CH),123.38 (CH), 122.86 (CH),
concentration between 5 and 0.1 mM. The product was not isolated;
1.93 (CH), 47.96 (CH ), 32.85 (CH ). ESI-MS. Calcd for [M −
data were taken from measurements on the reaction mixture.
2
2
+
1
PF ] : m/z 317.1509. Found: m/z 317.1518. Anal. Calcd
Metallacycle 18. H NMR (D O, 500 MHz): δ 9.38 (8H, d ), 9.03
6
2
ap
C H F N P: C, 46.76; H, 3.71; N, 18.18. Found: C, 46.63; H,
(4H, d, J = 6.7 Hz), 8.36 (4H, d, J = 9.2 Hz), 8.28 (4H, d, J = 9.2 Hz),
7.97−7.92 (4H, m), 6.50 (2H, q, J = 7.7 Hz), 3.72 (4H, m), 3.14−3.01
1
8
17
6
6
3
.84; N, 18.11.
F
DOI: 10.1021/acs.inorgchem.5b02650
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
1
3
(
(
(
(
2
4H, m), 3.00−2.92 (8H, m). C NMR (D O, 125 MHz): δ 152.28
= 6.8 Hz), 7.93 (4H, d, J = 6.7 Hz), 7.60 (4H, d, J = 6.6 Hz), 7.56 (8H,
s), 4.28 (2H, t, J = 7.8 Hz), 3.38 (4H, t, J = 6.6 Hz), 2.92 (8H, s),
2
CH), 148.09 (C), 147.99 (CH), 129.78 (CH), 129.40 (C), 128.12
13
C), 127.64 (CH), 127.53−127.50 (C), 125.85 (CH), 124.42−124.40
2.35−2.24 (4H, m), 1.65−1.55 (4H, m). C NMR (D O, 125 MHz):
2
C), 72.32 (CH), 57.05 (CH ), 46.86−46.81 (CH ), 33.24 (CH ),
δ 158.15 (C), 152.01 (CH), 151.00 (CH), 146.15 (C), 144.93 (C),
2
2
2
2.18 (CH ).
144.37 (CH), 140.83 (C), 129.58 (CH), 126.71 (C), 126.05 (CH),
2
1
Metallacycle 19. H NMR (D O, 500 MHz): δ 9.83 (8H, d ), 9.04
4H, d, J = 6.6 Hz), 8.37 (4H, d, J = 9.2 Hz), 8.28 (4H, d, J = 9.2 Hz),
120.01 (CH), 125.01 (CH), 124.21 (CH), 50.70 (CH ), 49.24 (CH),
2
ap
2
(
7
46.69−46.63 (CH ), 29.43 (CH ), 29.39 (CH ), 26.17 (CH ).
2
2
2
2
.99−7.91 (4H, m), 6.49 (2H, q, J = 7.9 Hz), 3.62 (2H, dt, J = 12.4
Metallacycle 27. A suspension of (±)-L15 (3.2 mg, 0.006 mmol)
and 7.5 Hz), 3.54 (2H, dt, J = 13.6 and 7.6 Hz), 3.16 (2H, dt, J = 14.9
and 7.6 Hz), 3.08 (2H, dt, J = 13.8 and 6.7 Hz), 3.02−2.90 (8H, m).
and (en)Pt(NO ) (5 mg, 0.006 mmol) in water (14 mL) was heated
3
2
at 150 °C for 3 h using microwave-assisted heating. After removal of
1
3
C NMR (D O, 125 MHz): δ 152.35 (CH), 148.05 (CH), 147.67−
2
the solvent under reduced pressure, the metallacycle 27 was obtained
1
1
1
4
47.62 (C), 129.86 (CH), 129.48 (C), 128.13 (C), 127.65 (CH),
27.57−127.55 (C), 125.79 (CH), 124.40−124.37 (C), 72.50 (CH),
6.96 (CH ), 46.87−46.82 (CH ), 30.20 (CH ), 30.14 (CH ).
as a solid (7.8 mg, 95%). H NMR (500 MHz, D O): δ 8.98 (4H, d, J
2
= 7.0 Hz), 8.96 (4H, d, J = 6.9 Hz), 8.71 (4H, d, J = 7.1 Hz), 8.33 (4H,
d, J = 6.6 Hz), 7.91 (4H, d, J = 6.9 Hz), 7.58 (4H, d, J = 6.8 Hz), 7.57
(8H, s), 4.30 (2H, q, J = 7.6 Hz), 4.07 (4H, q, J = 7.1 Hz), 2.85 (8H,
s), 2.55−2.46 (4H, m), 2.44 (4H, t, J = 7.0 Hz), 1.21 (6H, t, J = 7.1
2
2
2
2
1
Metallacycle 20. H NMR (D O, 500 MHz): δ 9.94 (4H, d ), 9.68
2
ap
(
4H, s), 8.82 (4H, d, J = 5.1 Hz), 8.57 (4H, d, J = 9.2 Hz), 8.47 (4H, d,
Hz). 13C NMR (125 MHz, D O): δ 175.68 (C), 157.44 (C), 152.83
J = 9.2 Hz), 7.57−7.54 (4H, m), 7.52−7.50 (4H, m), 7.44−7.40 (4H,
m), 4.26 (2H, t, J = 7.7 Hz), 4.07 (4H, q, J = 7.1 Hz), 2.95−2.86 (2H,
m), 2.83−2.72 (2H, m), 2.60−2.46 (4H, m), 2.47−2.37 (8H, m), 1.20
2
(
(
CH), 151.78 (CH), 144.93 (C), 144.63 (C), 144.37 (CH), 140.96
C), 129.69 (CH), 126.27 (CH), 125.98 (CH), 125.41 (CH), 124.23
(
(
(
(
(
(
6H, t, J = 7.2 Hz). 13C NMR (D O, 125 MHz): δ 175.69 (C), 157.52
2
(CH), 61.80 (CH ), 48.90 (CH), 47.43 (CH ), 32.09 (CH ), 27.38
2
2
2
C), 151.06 (CH), 148.10 (CH), 145.27 (C), 142.01 (C), 138.90
CH), 129.87 (CH), 129.79 (CH), 128.81 (C), 128.54 (C), 128.05
CH), 127.44 (C), 126.09 (CH), 126.06 (CH), 125.09 (C), 124.85
CH), 61.82 (CH ), 48.73−48.68 (CH), 46.87−46.80 (CH ), 32.04
CH ), 27.33 (CH ), 27.27 (CH ), 13.19 (CH ).
Metallacycle 21. H NMR (D O, 500 MHz): δ 9.94 (4H, d ), 9.66
4H, s), 8.81 (4H, d, J = 5.7 Hz), 8.56 (4H, d, J = 9.2 Hz), 8.46 (4H, d,
J = 9.1 Hz), 7.56 (4H, d, J = 5.7 Hz), 7.50 (4H, d, J = 8.6 Hz), 7.44
4H, d, J = 8.4 Hz), 4.26 (2H, t, J = 7.7 Hz), 3.38 (4H, t, J = 6.6 Hz),
.02 (8H, s), 2.31−2.54 (4H, m), 1.66−1.53 (4H, m). C NMR
D O, 125 MHz): δ 158.14 (C), 151.01 (CH), 148.09 (CH), 145.97
C), 141.84 (C), 138.85 (CH), 129.84 (CH), 129.68 (CH), 128.77
C), 128.51 (C), 128.01 (CH), 127.39 (C), 126.13 (CH), 125.04 (C),
24.77 (CH), 50.71 (CH ), 49.04−49.00 (CH), 46.86−46.78 (CH ),
9.38 (CH ), 29.33 (CH ), 26.14 (CH ).
Metallacycle 22. H NMR (500 MHz, D O): δ 8.96 (4H, d, J = 8.3
2+
(
CH ), 13.19 (CH ). ESI-MS. Calcd for [M − 2PF ] : m/z 969.1638.
2
3
6
2+
Found: m/z 969.1651. Calcd for [M − 3PF − H] : m/z 896.1778.
6
2+
Found: m/z 896.1784. Calcd for [M − 4PF − 2H] : m/z 823.1918.
6
+3
2
2
Found: m/z 823.1913. Calcd for [M − 4PF − H] : m/z 549.1303.
6
+3
2
2
2
3
Found: m/z 549.1322. Calcd for [M − 5PF − 2H] : m/z 500.4729.
1
6
2
ap
Found: m/z 500.4754.
(
Computational Methods. Full geometry optimizations of
metallacycle 22 were performed in an aqueous solution employing
(
3
(
(
(
1
2
30
DFT within the hybrid meta-GGA approximation with the M06
1
3
31
functional and the Gaussian 09 package (revision B.01). In these, we
2
used the standard 6-31G(d,p) basis set for carbon, hydrogen, nitrogen,
and oxygen atoms, while the palladium atom was treated using the
LanL2DZ effective core potential of Wadt and Hay and its associated
2
2
32
basis set. No symmetry constraints have been imposed during the
2
2
2
1
optimizations. The stationary points found on the potential energy
surfaces as a result of geometry optimizations were tested to represent
energy minima rather than saddle points via frequency analysis. The
default values for the integration grid (75 radial shells and 302 angular
2
Hz), 8.86−8.75 (8H, m), 8.18−8.09 (4H, m), 7.74 (4H, d, J = 6.9 Hz),
7
2
1
1
5
.71 (4H, d, J = 6.9 Hz), 6.12 (4H, t, J = 7.8 Hz), 3.68−3.52 (7H, m),
13
.82 (8H, s), 2.82−2.64 (4H, m). C NMR (125 MHz, D O): δ
2
−8
points) and the self-consistent-field energy convergence criteria (10 )
52.30 (CH), 152.158 (C), 152.02 (CH), 148.05 (C), 144.28 (C),
43.69 (CH), 126.59 (CH), 125.78 (CH), 124.75 (CH), 70.52 (CH),
were used in all calculations. Solvent effects were included by using the
polarizable continuum model. In particular, we used the integral
6.93 (CH ), 46.74 (CH ), 33.11 (CH ).
Metallacycle 23. H NMR (D O, 500 MHz): δ 9.05 (4H, d, J = 6.1
2
2
2
33
1
equation formalism variant, as implemented in Gaussian 09.
2
Hz), 8.92−8.86 (8H, m), 8.22 (4H, d, J = 6.3 Hz), 7.83 (4H, d, J = 6.8
Hz), 7.80 (4H, d, J = 6.8 Hz), 6.19 (2H, t, J = 7.6 Hz), 3.62−3.47 (4H,
ASSOCIATED CONTENT
13
■
m), 2.97−2.84 (12H, m). C NMR (D O, 125 MHz): δ 152.41
2
*
S
Supporting Information
(
1
4
CH), 152.33 (C), 152.05 (CH), 147.61 (C), 144.22−144.20 (C),
43.67 (CH), 126.72 (CH), 125.75 (CH), 124.77 (CH), 70.67 (CH),
6.84 (CH ), 46.74 (CH ), 30.12 (CH ).
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.5b02650.
2
2
2
1
Metallacycle 24. H NMR (500 MHz, D O): δ 8.98 (4H, d, J = 7.0
2
Hz), 8.94 (4H, d, J = 6.8 Hz), 8.68 (4H, d, J = 6.7 Hz), 8.31 (4H, d, J
7.0 Hz), 7.93 (4H, d, J = 6.9 Hz), 7.59 (4H, d, J = 6.9 Hz), 7.55 (8H,
s), 4.27 (2H, t, J = 7.8 Hz), 4.07 (4H, q, J = 7.1 Hz), 2.92 (8H, s),
=
1D and 2D NMR spectra for the compounds studied
(PDF)
2
.58−2.47 (m, 4H), 2.42 (4H, t, J = 7.1 Hz), 1.20 (6H, t, J = 7.2 Hz).
1
3
C NMR (125 MHz, D O): δ 175.68 (C), 157.49 (C), 151.99 (CH),
2
1
1
51.04 (CH), 145.40 (C), 144.89 (C), 144.34 (CH), 140.94 (C),
29.67 (CH), 126.03 (CH), 125.95 (CH), 124.98 (CH), 124.21
AUTHOR INFORMATION
■
Corresponding Authors
(
CH), 61.79 (CH ), 48.94 (CH), 46.66 (CH ), 32.09 (CH ), 27.32
2
2
2
(
CH ), 13.19 (CH ).
Metallacycle 25. H NMR (D O, 500 MHz): δ 8.98 (4H, d, J = 6.9
*E-mail: marcos.garcia1@udc.es. Tel: +34 981 167 000. Fax:
+34 981 167065.
2
3
1
2
Hz), 8.94 (4H, d, J = 6.7 Hz), 8.66 (4H, d, J = 6.6 Hz), 8.31 (4H, d, J
6.9 Hz), 7.93 (4H, d, J = 6.7 Hz), 7.59 (4H, d, J = 6.6 Hz), 7.55 (8H,
s), 4.27 (2H, t, J = 7.9 Hz), 3.64 (4H, t, J = 6.4 Hz), 2.92 (8H, s),
*E-mail: carlos.peinador@udc.es. Tel: +34 981 167 000. Fax:
=
+
34 981 167065.
13
Author Contributions
2
.34−2.16 (4H, m), 1.61−1.46 (4H, m). C NMR (D O, 125 MHz):
2
δ 158.31 (C), 152.01 (CH), 151.96 (C), 150.95 (CH), 146.32 (C),
The manuscript was written through contributions of all
authors. All authors have given approval to the final version of
the manuscript.
1
1
4
44.92 (C), 144.53 (CH), 140.78 (C), 129.58 (CH), 126.03 (CH),
26.01 (CH), 124.99 (CH), 124.16 (CH), 61.18 (CH ), 49.36 (CH),
2
6.70−46.62 (CH ), 29.33 (CH ), 28.65 (CH ), 28.61 (CH ).
2
2
2
2
1
Notes
Metallacycle 26. H NMR (D O, 500 MHz): δ 8.98 (4H, d, J = 6.9
2
Hz), 8.94 (4H, d, J = 6.6 Hz), 8.67 (4H, d, J = 6.4 Hz), 8.31 (4H, d, J
The authors declare no competing financial interest.
G
DOI: 10.1021/acs.inorgchem.5b02650
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
2
013, 110, 15585. (b) Zhou, Z.; Yan, X.; Cook, T. R.; Saha, M. L.;
ACKNOWLEDGMENTS
■
Stang, P. J. J. Am. Chem. Soc. 2016, 138, 806.
16) Jiang, B.; Zhang, J.; Ma, J.-Q.; Zheng, W.; Chen, L.-J.; Sun, B.;
́
This research was supported by the Ministerio de Economia y
Competitividad (MINECO FEDER, Grant CTQ201341097-P)
and Xunta de Galicia (Grant EM2014/056). T.R. and C.A.
thank the MECD and Universidade da Corun
financial support. V.B. thanks MINECO for a “Juan de la
Cierva” postdoctoral contract. The authors are also indebted to
(
Li, C.; Hu, B.-W.; Tan, H.; Li, X.; Yang, H.-B. J. Am. Chem. Soc. 2016,
138, 738.
(17) (a) Peinador, C.; Blanco, V.; García, M. D.; Quintela, J. M. Pd
II
̃
a, respectively, for
II
and Pt Metal-Directed Self-Assembly of Supramolecular Structures
Based on N-Monoalkyl-4,4′-Bipyridinium Derivatives. In Molecular
Self-Assembly: Advances and Applications; Li, A. D. Q., Ed.; Pan
Stanford Publishing: Singapore, 2012; p 351.
Centro de Supercomputacion de Galicia for providing the
́
computer facilities.
(
18) (a) Peinador, C.; Pía, E.; Blanco, V.; García, M. D.; Quintela, J.
M. Org. Lett. 2010, 12, 1380. (b) Blanco, V.; García, M. D.; Terenzi,
A.; Pía, E.; Fernandez-Mato, A.; Peinador, C.; Quintela, J. M. Chem. -
Eur. J. 2010, 16, 12373. (c) Alvarino, C.; Pía, E.; García, M. D.; Blanco,
V.; Fernandez, A.; Peinador, C.; Quintela, J. M. Chem. - Eur. J. 2013,
9, 15329. (d) Rama, T.; Lopez-Vidal, E. M.; García, M. D.; Peinador,
C.; Quintela, J. M. Chem. - Eur. J. 2015, 21, 9482.
19) (a) Blanco, V.; Chas, M.; Abella, D.; Peinador, C.; Quintela, J.
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2
(
(
2
2
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