Synthesis and Crystal Packing of trans-Bis(2-aminotroponato)palladium(II) Complexes Bearing Linear Alkyl Chains - Hard Lamellar Structures Self-Locked by Cross-Shaped Molecular Units

Article abstract of DOI:10.1002/ejic.201300914

The synthesis, structure, and three-dimensional lamellar array of a series of trans-bis(2-aminotroponato-κN,κO)palladium(II) complexes bearing linear alkyl chains (1a: n = 5; 1b: n = 8; 1c: n = 14; 1d: n = 16; 1e: n = 18, where n is the number of carbon atoms in the chain) attached to trans nitrogen donor atoms are described. The trans-coordination of the ligands, the cross-shaped molecular structures, and the crystal packing of 1b and 1c have been unequivocally established from single-crystal XRD studies. Highly regulated multilayered lamellar structures are observed for 1b and 1c, where every lamellar layer in the crystallographic ab plane, formed by π-stacking interactions of metal cores and van der Waals interactions between alkyl chains, is laminated alternately on the c axis with an orthogonal lamellar array of the identical unit. Powder XRD analysis showed that 1b-1e exhibit diffraction peaks attributed to periodic (n00) reflections of a typical lamellar structure. A linear correlation between the d-spacing and chain lengths in these compounds indicates that they form the same type of three-dimensional layer-by-layer structure of lamellar aggregates. The correlation between the cross-shaped molecular structures of 1b-1e and the dimensionality of molecular constraint in the crystal packing is discussed by comparison with those of rod-shaped analogues that exhibit high liquid crystallinity.

Full text of DOI:10.1002/ejic.201300914

FULL PAPER
DOI:10.1002/ejic.201300914
Synthesis and Crystal Packing of trans-Bis(2-
aminotroponato)palladium(II) Complexes Bearing Linear
Alkyl Chains – Hard Lamellar Structures Self-Locked by
Cross-Shaped Molecular Units
Naruyoshi Komiya,[a] Takao Hori,[a] Masaya Naito,[a] and
Takeshi Naota*[a]
Keywords: Palladium / Aminotroponato complexes / N,O ligands / Lamellar structures / Crystal engineering
The synthesis, structure, and three-dimensional lamellar
array of a series of trans-bis(2-aminotroponato-κN,κO)palla-
dium(II) complexes bearing linear alkyl chains (1a: n = 5; 1b:
n = 8; 1c: n = 14; 1d: n = 16; 1e: n = 18, where n is the number
of carbon atoms in the chain) attached to trans nitrogen do-
nor atoms are described. The trans-coordination of the li-
gands, the cross-shaped molecular structures, and the crystal
packing of 1b and 1c have been unequivocally established
from single-crystal XRD studies. Highly regulated multilay-
ered lamellar structures are observed for 1b and 1c, where
every lamellar layer in the crystallographic ab plane, formed
by π-stacking interactions of metal cores and van der Waals
interactions between alkyl chains, is laminated alternately on
the c axis with an orthogonal lamellar array of the identical
unit. Powder XRD analysis showed that 1b–1e exhibit diffrac-
tion peaks attributed to periodic (n00) reflections of a typical
lamellar structure. A linear correlation between the d-spac-
ing and chain lengths in these compounds indicates that they
form the same type of three-dimensional layer-by-layer
structure of lamellar aggregates. The correlation between the
cross-shaped molecular structures of 1b–1e and the dimen-
sionality of molecular constraint in the crystal packing is dis-
cussed by comparison with those of rod-shaped analogues
that exhibit high liquid crystallinity.
condensed state, due to the low-dimensional aggregation
properties. In contrast to the soft lamellar structures of the
above complexes, hard lamellar crystals have been reported
to form in the limited cases of less planar, long-chained
complexes such as ferrocene,[7] [Cu(OSO2R)2],[8] [Cu2-
(OCOR)4],[9] [Zn2(OAc)4(tpy–OR)2],[10] and [AgBr2-
(NHCR)2] (NHC: N-heterocyclic carbene).[11]
Introduction
The elucidation and application of lamellar arrange-
ments of linear chain molecules are important for the devel-
opment of new materials whose functions rely on molecular
aggregation. Lamellar crystals have been studied in order
to investigate the higher order structures of various poly-
mers such as paraffins,[1] polyolefins,[2] polyamides,[3] poly-
urethanes,[4] and polyesters.[5] In the fields of inorganic and
organometallic chemistry, similar layered structures have
been extensively studied using transition metal complexes
bearing long alkyl chains, with the aim of achieving liquid
crystalline properties. A variety of transition metal com-
plexes bearing square-planar coordination sites to which
long alkyl chains are appended have been reported to act
as efficient mesogens.[6] These complexes typically have
long, rod-like molecular shapes due to pairs of trans-dis-
posed linear alkyl chains along the axial direction of the
molecule. This characteristic molecular shape generates a
moderate balance of molecular mobility and rigidity in the
Hard lamellar crystals of diads comprising transition
metals and alkyl chains could potentially express a variety
of photoelectric properties upon morphological control of
the functional metal cores, although, in contrast to exten-
sive studies on the liquid crystalline properties of soft lam-
ellar structures, this has not yet been investigated.[6] As part
of our program aimed at developing new functionalities of
square-planar d8 transition metal complexes,[12] we recently
showed that typically nonemissive crystals of trans-bis(sali-
cylaldiminato)platinum(II) complexes bearing long alkyl
chains can be changed to highly emissive crystals by mor-
phological control of the lamellar structure through crystal
engineering.[13] This result indicates that an understanding
of the correlation between lamellar structures and the shape
of molecular units can aid in the design of future photoelec-
tric devices. In this paper, we investigate the molecular ar-
rays formed by trans-bis(2-aminotroponato-κN,κO)palladi-
um(II) complexes (1) bearing long alkyl chains attached to
trans nitrogen donor atoms in the crystalline state
[a] Department of Chemistry, Graduate School of Engineering
Science, Osaka University,
Machikaneyama, Toyonaka, Osaka 560-8531, Japan
E-mail: naota@chem.es.osaka-u.ac.jp
http://www.soc.chem.es.osaka-u.ac.jp/english/index.html
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201300914.
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(Scheme 1).[14] Unlike the rod-shaped (alkoxytroponato)- XRD (Table 1). ORTEP drawings of 1b and 1c are shown
metal analogues,[14f,15] cross-shaped complexes 1 with in Figures 1 and 2. The tropone rings, ligand donor atoms,
“horizontal” alkyl chains form hard lamellar crystals with and metal ion are essentially coplanar, as indicated by the
nonmesogenic properties. Single-crystal XRD analyses of small dihedral angles between the coordination plane [Pd1–
1b and 1c, and powder XRD analyses of 1a–1e, show that
1b–1e consist of characteristic multilayered lamellar struc-
tures, where each lamellar layer is laminated alternately
with another identical lamellar layer rotated by 180°.
Table 1. Crystal data and structure refinement details for com-
pounds 1b and 1c.
1b
1c
Formula
Formula weight
Temperature /K
C30H44N2O2Pd
571.09
113
C42H68N2O2Pd
739.41
113
Crystal color, habit red, platelets
red, platelets
0.24ϫ0.12ϫ0.04
monoclinic
P21/c (#14)
22.083(2)
4.9812(3)
17.903(1)
90
Crystal size /mm
Crystal system
Space group
a /Å
0.60ϫ0.20ϫ0.04
monoclinic
P21/c (#14)
14.963(3)
5.0165(8)
18.774(4)
90
b /Å
c /Å
α /°
β /°
96.808(5)
90
1399.2(4)
2
1.355
6.918
95.354(2)
90
1960.7(2)
2
1.252
5.093
γ /°
V /Å3
Scheme 1.
Z
Dcalcd. /gcm–3
μ(Mo-Kα) /cm–1
F(000)
Both the structure and crystal packing show that high
600.00
55.0
792.00
54.9
dimensionality in self-constrained molecular units can be
attributed to the specific anisotropy of the intermolecular
interactions, which results from the cross-shaped structures
of 1b–1e. Recently we reported that the self-constraint of
molecular units in the condensed state is one of the major
controlling factors in the intense solid-state phosphores-
cence of platinum complexes.[12b–12e,13] The present results
provide significant information regarding the correlation
between molecular shape and self-constraint of the molecu-
lar units in crystals, which will aid in the design of hard
and soft matter with excellent photoelectric properties.
2θmax /°
No. of reflns. measd. 24278
No. of obsd. reflns. 3195
38387
4467
215
0.064
0.168
1.15
No. of variables
R1 [IϾ2σ(I)][a]
wR2 (all reflns.)[b]
Goodness of fit
248
0.055
0.168
1.19
2
2 2
[a] R1 = Σ(|Fo| – |Fc|)/Σ(|Fo|). [b] wR2 = {Σ[w(Fo – Fc ) ]/
Σw(Fo2)2}1/2
.
Results and Discussion
Synthesis and Characterization of 1
The
trans-bis(aminotroponato-κN,κO)palladium(II)
complexes 1a–1e, bearing linear alkyl chains (1a: n = 5; 1b:
n = 8; 1c: n = 14; 1d: n = 16; 1e: n = 18, where n is the
number of carbon atoms in the chain) were synthesized by
the reaction of [Pd(OAc)2] with the corresponding 2-(alk-
ylamino)tropone in the presence of N,N,NЈ,NЈ-tetramethyl-
ethylenediamine in refluxing toluene at reflux. The 2-(alk-
ylamino)tropones were prepared by reaction of tropolone
with SOCl2 and subsequent amination of the resulting
1
chloride.[16] Complexes 1a–1e were characterized using H
Figure 1. ORTEP drawing of 1b. (a) Top and (b) side views [C5–
C5Ј projection]. Thermal ellipsoids are shown at the 50% prob-
ability level. Hydrogen atoms are omitted for clarity. Selected bond
lengths (in Å) and angles (in °): Pd1–O1 1.986(3), Pd1–N1 1.977(4),
O1–C1 1.305(6), N1–C2 1.324(6); O1–Pd1–N1 80.40(13), O1–Pd1–
NMR, 13C NMR (Figures S1–S5, Supporting Infor-
mation), and FTIR spectroscopy, and high-resolution mass
spectrometry. The trans disposition of the alkyl groups in 1b
and 1c has been unequivocally established by single-crystal N1Ј 99.60(13), O1–Pd1–N1–C2 1.7(3), N1–Pd1–O1–C1 0.3(2).
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Figure 2. ORTEP drawing of 1c. (a) Top and (b) side views [C5–C5Ј projection]. Thermal ellipsoids are shown at the 50% probability
level. Hydrogen atoms are omitted for clarity. Selected bond lengths (in Å) and angles (in °): Pd1–O1 1.985(3), Pd1–N1 1.979(4), O1–C1
1.301(6), N1–C2 1.334(6); O1–Pd1–N1 80.55(14), O1–Pd1–N1Ј 99.45(14), O1–Pd1–N1–C2 1.6(2), N1–Pd1–O1–C1 1.9(2).
O1–N1] and the tropone ring [C1–C3–C5] (2.50° 1b, 1.22° XRD Studies on Lamellar Crystals 1
1c) as well as the small [C1–C2–N1–Pd1] (2.69° 1b, 1.21°
1c) and [C2–C1–O1–Pd1] (1.10° 1b, 1.76° 1c) torsion angles.
Intramolecular H-bonding interactions between O1 and
H8Ј are observed, with distances of 2.54 (for 1b) and 2.58
(for 1c) Å. The characteristic conformation observed for
both 1b and 1c, where horizontal alkyl chains extend above
and below the square plane, (Figures 1b and 2b), is note-
worthy. As discussed later, such a conformation induces
high dimensionality with significant intermolecular con-
straint of the crystals. Complexes 1b–1e immediately form
platelet crystals when hot solutions in various solvents such
as cyclohexane, benzene, toluene, EtOAc, and THF are co-
oled to room temperature. Scanning electron microscopy
(SEM) images of microcrystalline 1c and 1e obtained from
EtOAc are shown in Figure 3. Differential scanning calo-
rimetry (DSC) analysis (Figure S6, Supporting Infor-
mation) and polarized microscopy observations indicate
that complexes 1a–1e do not exhibit mesophases.
Packing diagrams of 1b and 1c are shown in Figure 4.
The most important features evident in these diagrams are
the multilayered lamellar motifs, which are supported by
π-stacking interactions between the planar regions of the
complexes, and van der Waals forces between the linear
alkyl chains. Single-layered lamellar structures viewed down
the c axis are shown in Figure 4a and 4d, where the trans-
bis(2-aminotroponato)Pd unit of each molecule is aligned
along the crystallographic b axis on the ab plane, giving π-
stacking interactions with distances of 3.50 Å (for 1b) and
3.48 Å (for 1c). Alkyl chains are aligned in a highly linear
manner with a typical zigzag conformation, assisted by
van der Waals interactions between neighboring cofacial
molecular units. Note that every lamellar layer in the ab
plane is laminated alternately along the c axis with another
lamellar layer, where each molecular unit is identical, but
rotated 180° about the c axis [symmetry code: (-x, 1/2 + y,
1/2 – z), (x, 1/2 – y, 1/2 + z)]. Such a characteristic layer-
by-layer structure, which consists of alternate stacking of
orthogonal arrays of each unit, can be visualized by viewing
down the c axis (Figure 4b, e) or b axis (Figure 4c, f). Close-
up views of adjacent stacked pairs of 1b and 1c molecules
(Figure 5a, b) indicate that each molecular unit undergoes
typical offset stacking between O1 and the C3–C4–C5 plane
of the tropone ring. The contribution of the “2-aminotro-
pone” form is greater than that of the “2-hydroxytropone
imine” form in (2-aminotroponato)metal complexes,[14d] so
that the offset stacking shown in Figure 5 is attributed to a
donor–acceptor interaction between the electron-deficient
Figure 3. SEM images of microcrystalline (a) 1c and (b) 1e ob-
tained by crystallization from hot EtOAc solution.
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Figure 4. Packing of (a–c) 1b and (d–f) 1c. (a,d) Single-layered lamellar structures in the ab plane (c axis projection). (b,e) Multilayered
lamellar structures in the ab plane (c axis projection), and (c,f) side views in the ac plane (b axis projection). Molecular units in the upper
and lower layers of the ab plane are colored orange. Hydrogen atoms are omitted for clarity.
carbonyl [C1–O1] and electron-rich 1,3-dienamine [N1–C2–
C3–C4–C5] moieties of the tropone rings. The coordination
planes on each layer are hydrogen-bonded to each other
through the O1 and H6 atoms of the tropone ring, as shown
in Figure 5c and 5d, which means that each lamellar layer
experiences both intermolecular hydrogen-bonding and
van der Waals interactions to form the multilayered lam-
ellar structure.
Powder XRD patterns of 1b–1e (n = 8–18) show a series
of sharp diffraction peaks attributable to the typical lam-
ellar reflection of a multilayered structure, while the pattern
of 1a, which contains shorter chains, (n = 5) is different
(Figure 6). Layer spacings (d-spacings) for 1b (15.2 Å) and
1c (22.5 Å) are in accordance with the a axis lengths of each
unit cell (15.0 Å, 22.1 Å), which indicates that the major
peaks in these XRD patterns are due to the (100), (200),
and (300) reflections. Figure 7 shows the correlation be-
tween chain length (n) and d-spacing estimated by indexing
the diffraction peaks of the (100) reflections. The d-spacings
of 1b–1e increase essentially proportionally to the chain
lengths (R2 = 0.999); however, that of 1a is much longer
Figure 5. Major interactions between the coordination planes in
than that expected from this relationship. These results indi-
crystals of (a,c) 1b and (b,d) 1c. (a,b) Offset π-stacking interaction
cate that 1b–1e, which contain long alkyl chains, have sim-
ilar multilayered lamellar structures, while 1a forms a non-
in the single lamellar layer. (c,d) Interlayer hydrogen-bonding inter-
action. Molecular units in the upper layer of the ab plane are col-
lamellar packing motif.
ored orange.
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Figure 6. XRD patterns for crystals of (a) 1a, (b) 1b, (c) 1c, (d) 1d, and (e) 1e. The calculated interlayer spacings from the (100) reflections
are listed in each pattern.
soft lamellar structures that exhibit high mesogenic proper-
ties. This can be rationalized by assuming anisotropy in
both the π-stacking and van der Waals interactions of these
molecular units in lamellar aggregates. Both of the cross-
and rod-shaped units form layer-by-layer lamellar struc-
tures upon molecular aggregation. Each molecular unit ex-
periences consecutive π-stacking interactions between the
coordination planes and van der Waals forces between long
alkyl chains to form a single-layered lamellar structure,
which becomes increasingly multistratified, mainly as a re-
sult of the van der Waals forces between the alkyl chains.
Assuming that the most efficient direction for molecular
mobility in the crystals is perpendicular to the direction of
the axis for consecutive stacking and van der Waals interac-
tions, then the direction of molecular mobility to break the
π-stacking interactions in 1b–1e is perpendicular to that
needed for breaking the van der Waals interactions in sin-
Figure 7. Correlation between chain length (n) and interlayer spac-
gle-layered lamellar arrays (Figure 8a). As shown in the
packing of 1b and 1c (Figure 4b, e), this single layer is lami-
nated to afford the multilayered lamellar structure in an
alternate manner, where the upper identical lamellar layer
of 1b and 1c units is situated orthogonally over the original
layer to maximize the interlayer interactions. Thus, the di-
rection of molecular mobility to unlock the π-stacking in-
ings (d-spacings) in 1a–1e.
Molecular Mobility of Cross- and Rod-Shaped Molecules in
the Lamellar Arrangement
The correlation between the molecular shape and lamellar teraction between molecular units on the lower horizontal
structure for typical cross- and rod-shaped molecules is single lamellar layer should be perpendicular to that on the
shown in Figure 8. Cross-shaped complexes 1b–1e form upper layer. This means that three-dimensional molecular
hard lamellar structures that are not liquid crystals. This mobility is required to unlock the overall self-constraint in
is in contrast to the rod-shaped, square-planar complexes the crystal packing of the cross-shaped molecules 1b–1e.
bearing trans-bis(5-alkoxy-2-aminotroponato)[14f] and bis(4-
In contrast to complexes 1b–1e, the molecular constraint
alkoxytroponato)[15] ligands, which form low-dimensional of rod-shaped complexes with high mesogenic properties is
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Figure 8. Schematic representation of morphological differences in lamellar aggregates of square-planar metal complexes bearing long
alkyl chains. Arrows denote the direction of molecular mobility required to break π-stacking (red) and van der Waals (blue) interactions.
quite homogeneous, as indicated by the highly regulated ergy in the development of future light-emitting de-
lamellar packing of the mesogenic bis(4-hexadecyloxytro- vices.[12b–12d,13] We have shown that molecular design can
ponato)copper(II) complex[15b] shown in Figure 8b. As a be used to reduce molecular mobility of a lamellar struc-
corollary of the rod-shaped molecular structure, the direc- ture, which will aid in the design of functional photoelectric
tion of molecular mobility to cleave π-stacking interactions materials with morphological control of lamellar structures.
is the same as that needed to cleave the van der Waals inter- Further research is currently underway.
actions between alkyl chains in a single lamellar layer. The
overall direction for breaking the interactions is not
changed in the multilayered structure, because the upper Experimental Section
single lamellar layer is identical to the neighboring layers in
this case. This simple dimensionality in molecular con-
straint is the key to high mobility, that is, the low self-con-
straint of rod-shaped molecular units in a condensed sys-
tem. Figure 4 and Figure 5 show that the significant inter-
General: A series of trans-bis[2-(N-alkylamino)troponato-κN,κO]-
palladium(II) complexes 1a–1e was synthesized by reaction of
Pd(OAc)2 with the corresponding 2-(alkylamino)tropone[16]
(2 equiv.) in the presence of N,N,NЈ,NЈ-tetramethylethylenediamine
in boiling toluene. Melting points were measured in a glass capil-
layer interactions in 1b and 1c are limited to van der Waals lary with a Büchi B-545 melting point apparatus. Mass spectra were
obtained with a JEOL JMS-DX 303 spectrometer. FTIR spectra
were recorded with a Bruker EQUINOX55/S spectrometer. 1H and
13C NMR spectra were recorded with a Varian Unity-Inova 500
spectrometer. SEM images were obtained with a KEYENCE VE-
7800. DSC was carried out with a Shimadzu DSC-60 instrument.
XRD analyses for single crystals were conducted with a Rigaku
R-AXIS RAPID imaging plate diffractometer by using graphite-
monochromated Mo-Kα radiation. Powder XRD analyses were per-
formed with a Philips XЈPert-MPD diffractometer by using Cu-Kα
radiation.
interactions between alkyl chains and hydrogen bonding be-
tween the coordination planes. There is no significant π-
stacking and CH–π contact in the interlayer interactions.
Therefore, the overall interlayer interactions in the cross-
shaped complex crystals are not significantly greater than
those of the rod-shaped analogues. Thus, it is fairly certain
that the rigidity of the cross-shaped molecular units in the
lamellar arrangement is not due to the total strength of
intermolecular interactions, but is rather a result of the high
dimensionality in molecular mobility required to break the
interactions.
Compound 1a: Orange solid (24%). M.p. 116–117 °C. IR (KBr): ν
˜
= 2955, 2926, 2859, 2360, 2342, 1599, 1566, 1511, 1466, 1444, 1410,
1404, 1317, 1275, 1217, 1108, 883, 752, 725 cm–1. 1H NMR (500
MHz, CDCl3): δ = 0.93 (t, J = 7.0 Hz, 6 H), 1.32–1.50 (m, 8 H),
1.69 (tt, J = 7.4, 7.4 Hz, 4 H), 3.42 (t, J = 7.4 Hz, 4 H), 6.38 (dd,
J = 9.9, 8.9 Hz, 2 H, 5-H), 6.59 (d, J = 9.9 Hz, 2 H, 7-H), 6.65 (d,
J = 11.9 Hz, 2 H, 3-H), 6.88 (ddd, J = 9.9, 9.9, 1.1 Hz, 2 H, 6-H),
6.94 (ddd, J = 11.9, 8.9, 1.1 Hz, 2 H, 4-H) ppm. 13C NMR (125
MHz, CDCl3): δ = 14.1, 22.5, 27.7, 29.4, 49.7, 117.1, 119.3, 121.6,
133.9, 134.5, 168.3, 181.8 ppm. HRMS (FAB+): calcd. for
C24H32N2O2106Pd [M]+ 486.1499; found 486.1525.
Conclusions
A series of cross-shaped complexes based on trans-bis(2-
aminotroponato)palladium(II), and bearing long alkyl
chains, was synthesized. These complexes form hard lam-
ellar crystals, in contrast to the typical rod-shaped ana-
logues of metallomesogens. Single-crystal and powder XRD
analyses revealed that anisotropic intermolecular interac-
tions specifically arising from cross-shaped molecular units
is the key to high molecular constraint within the three-
dimensional, hard lamellar structure of 1b–1e. Morphologi-
cal control to enhance self-constraint of molecular aggre-
Compound 1b: Orange solid (46%). M.p. 95–96 °C. IR (KBr): ν =
˜
2919, 2855, 1599, 1568, 1514, 1446, 1402, 1319, 1273, 1220,
1
716 cm–1. H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 7.0 Hz, 6
H), 1.21–1.41 (m, 16 H), 1.45 (tt, J = 7.4, 7.4 Hz, 4 H), 1.68 (tt, J
= 7.4, 7.4 Hz, 4 H), 3.41 (t, J = 7.4 Hz, 4 H), 6.38 (dd, J = 10.4,
8.8 Hz, 2 H, 5-H), 6.59 (d, J = 10.4 Hz, 2 H, 7-H), 6.65 (d, J =
gates will be important to avoid dispersion of photon en- 11.8 Hz, 2 H, 3-H), 6.88 (ddd, J = 10.4, 10.4, 1.1 Hz, 2 H, 6-H),
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6.93 (ddd, J = 11.8, 8.8, 1.1 Hz, 2 H, 4-H) ppm. 13C NMR (125
MHz, CDCl3): δ = 14.1, 22.7, 27.3, 28.0, 29.3, 29.4, 31.9, 49.7,
117.1, 119.3, 121.6, 133.8, 134.4, 168.3, 181.8 ppm. HRMS (FAB+):
calcd. for C30H44N2O2106Pd [M]+ 570.2438; found 570.2447.
Acknowledgments
This work was supported by a Grant-in-Aid for Scientific Research
from the Ministry of Education, Culture, Sports, Science and Tech-
nology, Japan.
Compound 1c: Orange solid (46%). M.p. 94–95 °C. IR (KBr): ν =
˜
2919, 2850, 1599, 1568, 1513, 1446, 1404, 1320, 1275, 1220,
1
718 cm–1. H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 7.0 Hz, 6
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H, CH3), 1.20–1.33 (m, 36 H), 1.33–1.40 (m, 4 H), 1.45 (tt, J = 7.4,
7.4 Hz, 4 H), 1.68 (tt, J = 7.4, 7.4 Hz, 4 H), 3.41 (t, J = 7.4 Hz, 4
H), 6.39 (dd, J = 10.3, 8.8 Hz, 2 H, 5-H), 6.59 (d, J = 10.4 Hz, 2
H, 7-H), 6.65 (d, J = 11.8 Hz, 2 H, 3-H), 6.87 (ddd, J = 10.3, 10.3,
1.1 Hz, 2 H, 6-H), 6.94 (ddd, J = 11.8, 8.8, 1.1 Hz, 2 H, 4-H) ppm.
13C NMR (125 MHz, CDCl3): δ = 14.1, 22.7, 27.3, 28.0, 29.4, 29.5,
29.61, 29.66, 29.69, 29.70, 29.71, 31.9, 49.7, 117.1, 119.3, 121.6,
133.9, 134.4, 168.3, 181.8 ppm. HRMS (FAB+): calcd. for
C42H68N2O2105Pd [M]+ 737.4331; found 737.4331.
Compound 1d: Orange solid (39%). M.p. 99–100 °C. IR (KBr): ν =
˜
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2919, 2850, 1599, 1513, 1468, 1445, 1405, 1320, 1221, 720 cm–1. 1H
NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 6.7 Hz, 6 H), 1.15–1.53
(m, 52 H), 1.68 (tt, J = 7.4, 7.4 Hz, 4 H), 3.41 (t, J = 7.4 Hz, 4 H),
6.38 (dd, J = 10.3, 8.8 Hz, 2 H, 5-H), 6.59 (dd, J = 10.2, 0.8 Hz, 2
H, 7-H), 6.65 (d, J = 11.9 Hz, 2 H, 3-H), 6.87 (ddd, J = 10.2, 10.2,
1.1 Hz, 2 H, 6-H), 6.94 (ddd, J = 11.9, 8.8, 1.1 Hz, 2 H, 4-H) ppm.
13C NMR (125 MHz, CDCl3): δ = 14.1, 22.7, 27.3, 27.9, 29.4, 29.5,
29.62, 29.67, 29.70, 29.71, 31.7, 49.7, 117.1, 119.3, 121.6, 133.9,
134.4, 168.3, 181.8 ppm. HRMS (FAB+): calcd. for
C46H76N2O2106Pd [M]+ 794.4942; found 794.4922.
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Compound 1e: Orange solid (29%). M.p. 97–98 °C. IR (KBr): ν =
˜
2919, 2850, 1599, 1568, 1513, 1446, 1404, 1320, 1274, 1220,
1
719 cm–1. H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 7.0 Hz, 6
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H), 1.20–1.33 (m, 56 H), 1.33–1.40 (m, 4 H), 1.45 (tt, J = 7.4,
7.4 Hz, 4 H), 1.68 (tt, J = 7.4, 7.4 Hz, 4 H), 3.41 (t, J = 7.4 Hz, 4
H), 6.39 (dd, J = 10.2, 8.8 Hz, 2 H, 5-H), 6.59 (d, J = 10.2 Hz, 2
H, 7-H), 6.65 (d, J = 11.8 Hz, 2 H, 3-H), 6.87 (ddd, J = 10.2, 10.2,
1.1 Hz, 2 H, 6-H), 6.94 (ddd, J = 11.8, 8.8, 1.1 Hz, 2 H, 4-H) ppm.
13C NMR (125 MHz, CDCl3): δ = 14.1, 22.7, 27.3, 28.0, 29.4, 29.5,
29.62, 29.66, 29.71, 31.9, 49.7, 117.1, 119.3, 121.6, 133.9, 134.4,
168.3, 181.8 ppm. HRMS (FAB+): calcd. for C50H84N2O2106Pd
[M]+ 850.5568; found 850.5596.
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X-ray Structure Determination: Crystals suitable for XRD studies
were obtained by recrystallization from ethyl acetate and analyzed
by using a Rigaku R-AXIS RAPID imaging plate diffractometer
with graphite-monochromated Mo-Kα radiation (λ = 0.71075 Å).
The structures of 1b and 1c were solved by direct methods and
refined using the full-matrix least-squares method. In the subse-
quent refinement, the function Σω(Fo – Fc ) was minimized (Fo
and Fc are the observed and calculated structure factor amplitudes,
respectively). The positions of non-hydrogen atoms were found
from difference Fourier electron density maps and were refined an-
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determinations are given in Table 1, Figure 1 and Figure 2. CCDC-
947886 (for 1b) and -947887 (for 1c) contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
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2 2
Supporting Information (see footnote on the first page of this arti-
cle): H and 13C NMR spectra of 1a–1e and DSC thermogram of
1
1b.
Eur. J. Inorg. Chem. 2014, 156–163
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© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
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Received: July 17, 2013
Published Online: November 15, 2013
Eur. J. Inorg. Chem. 2014, 156–163
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© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim