Self-assembly and substituent effect of copper(I) complexes with 1,2-bis(2-pyridylethynyl)benzene ligands

Article abstract of DOI:10.1246/bcsj.76.789

The reaction of 1,2-bis(2-pyridylethynyl)benzenes (L1-L5) with copper(I) ions proceeded smoothly to afford mononuclear copper(I) chelate complexes CL1-CL3 or dinuclear copper(I) molecular rectangular boxes, CL4 and CL5, in excellent yields, depending on the size of the substituent. If a ligand with a small substituent was used, the self-assembly of a mononuclear copper(I) chelate complex was achieved. If a ligand with a bulky substituent was used, the self-assembly of dinuclear copper(I) molecular rectangular boxes was achieved. The equilibrium between these two copper(I) complexes was also observed in solution.

Full text of DOI:10.1246/bcsj.76.789

ꢀ 2003 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 76, 789–797 (2003)
789
Self-Assembly and Substituent Effect of Copper(a) Complexes
with 1,2-Bis(2-pyridylethynyl)benzene Ligands
ꢀ
ꢀ
Tomikazu Kawano, Jun Kuwana, and Ikuo Ueda
The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047
(Received October 7, 2002)
The reaction of 1,2-bis(2-pyridylethynyl)benzenes (L1–L5) with copper(a) ions proceeded smoothly to afford
mononuclear copper(a) chelate complexes CL1–CL3 or dinuclear copper(a) molecular rectangular boxes, CL4 and CL5, in
excellent yields, depending on the size of the substituent. If a ligand with a small substituent was used, the self-assembly of a
mononuclear copper(a) chelate complex was achieved. If a ligand with a bulky substituent was used, the self-assembly of
dinuclear copper(a) molecular rectangular boxes was achieved. The equilibrium between these two copper(a) complexes was
also observed in solution.
The metal ion-assisted self-assembly of functionalized higher
order supramolecular structures is currently of interest in the field
of metallosupramolecular chemistry.1 In metallosupramolecular
chemistry, the self-assembly of defined species in thermodyna-
mically controlled processes is achieved by the mixing of metal
ions with appropriate organic ligands in solution. Therefore,
various factors, such as the suitable design of ligands, preferred
coordination geometries of the metals, and templating effects,
play a pivotal role in the self-assembly process.2;3 In our previous
communication, we reported that the coordination of ꢀ-con-
jugated nitrogen ligands, 1,2-bis(2-pyridylethynyl)benzenes,4
with copper(a) ion led to the self-assembly of mononuclear
chelate complexes or dinuclear molecular rectangular boxes.5;6
These previous reports suggest thatthe self-assemblyof copper(a)
complexes from 1,2-bis(2-pyridylethynyl)benzenes should de-
pend on the size of the substituent of the ligand. Far less attention
has been devoted to the substituent effect in the self-assembly of
such a mononuclear chelate complex and a dinuclear molecular
rectangular box, althoughmanyreportsonthesubstituenteffect in
the self-assembly of metal complexes have been documented in
the literature to date.7 It was therefore expected that 1,2-bis(2-
pyridylethynyl)benzenes should be one of the best ligands for
investigating the substituent effect in the self-assembly of the
copper(a) complex. We describe herein the self-assembly and
substituent effects of copper(a) complexes from 1,2-bis(2-pyri-
dylethynyl)benzenes in detail.
in 95% yield, and then displacement of the resulting mesyl group
with iodide in acetone at 60 ꢁC afforded the corresponding
primary iodide 5 in 98% yield. The reaction of sodium salts of
phenol, L-menthol, or D-menthol with iodide 5 at 0 ꢁC gave the 6-
(phenoxymethyl) 6, 6-(L-menthyloxymethyl) 7, and 6-(D-men-
thyloxymethyl) derivatives 8 in 93%, 99%, and 94% yields,
respectively. This synthetic protocol allows the preparation of 2-
bromopyridine derivatives with a variety of substituents at the 6-
position. The cross-coupling reaction of 1,2-bis(ethynyl)benzene
(1) with the corresponding 2-bromopyridine derivatives in the
presence of a catalytic amount of tetrakis(triphenylphosphine)-
palladium in diethylamine at 80 ꢁC afforded the desired ligands
L1–L5 in 72%, 92%, 95%, 68%, and 72% yields, respectively.
All ligands obtained were characterized by spectroscopy (NMR,
IR, and FAB mass) and elemental analysis.
Self-Assembly of Copper(a) Complexes. We first examined
the coordination of the ligand L2 with the copper(a) ion. The
11
reaction of L2 with an equimolar quantity of [Cu(CH3CN)4]PF6
in dichloromethane (CH2Cl2) at room temperature resulted in the
immediate formation of yellow solutions, indicating a fast
complexation with copper(a) ions, from which the desired
copper(a) complex CL2 was obtained as yellow blocks in 90%
1
yield (Scheme 2). The H NMR spectra of CL2 in dichloro-
methane-d2 solution consisted of a simple pattern of peaks
corresponding to L2, indicative of the formation of a symmetric
species (Fig. 1). Uponmetalcomplexation, specific signals of the
1H NMR spectra undergo significant changes, which also make
these signals key indicators of complexation. The signals of all
the aromatic protons involved in CL2 were shifted relative to
those involved in L2. In particular, the proton signal (Hd) of the
pyridine ring (ꢀꢁ ¼ 0:38) is shifted downfield relative to that of
the free ligand L2. The UV electronic spectra of CL2 displayed a
new absorption atapproximately360 nm, which was assigned toa
metal-to-ligand charge-transfer band (Fig. 2a). The change in
absorbance analyzed by the mole ratio method at 358 nm showed
a lineardependence onthe amountofcopper(a) salt addeduptoan
approximately 1:1 L2:copper(a) ratio (Fig. 2b). This result
indicates that a [Cu(L2)]þ composition is generated. Further-
Results and Discussion
Preparation of the Ligands L1–L5. The synthesisofligands
L1–L5 in this study is outlined in Scheme 1. 1,2-Bis(ethynyl)-
benzene (1) was prepared according to a previously described
procedure.8 The reaction of the sodium salt of 2-bromo-6-
(hydroxymethyl)pyridine (2),9;10 which was prepared by treat-
ment of 2 with sodium hydride in tetrahydrofuran (THF) at 0 ꢁC,
with methyl iodide in THF at 0 ꢁC afforded 2-bromo-6-
(methoxymethyl)pyridine (3) in 97% yield. Treatment of 2 with
methanesulfonyl chloride in the presence of triethylamine and 4-
(dimethylamino)pyridine in THF at ꢂ40 ꢁC gave the mesylate 4

790 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Substituent Effect in the Self-Assembly
Scheme 1. Preparation of theligands (L1–L5). Reagents andconditions: (a) TMSacetylene, PdCl2(PPh3)2, CuI, piperidine, rt, 95%. (b)
TBAF, THF–H2O, 0 ꢁC to rt, 83%. (c) (1) n-BuLi, THF, ꢂ78 ꢁC, (2) DMF, THF, ꢂ78 ꢁC, (3) NaBH4, THF, 0 ꢁC, 87%. (d) (1) NaH,
THF, 0 ꢁC, (2) MeI, THF, 0 ꢁC, 97%. (e) MsCl, Et3N, DMAP, THF, ꢂ40 ꢁC, 95%. (f) NaI, acetone, 60 ꢁC, 98%. (g) PhONa, THF, 0
ꢁC, 93% (for 6), sodium L-menthoxide, THF, 0 ꢁC, 99% (for 7), or sodium D-menthoxide, THF, 0 ꢁC, 94% (for 8). (h) Pd(PPh3)4,
Et2NH, 80 ꢁC, 72% (for L1), 92% (for L2), 95% (for L3), 68% (for L4), and 72% (for L5).
Scheme 2. Synthesis of the copper(a) complexes (L1–L5). Yield: 87% (for CL1), 90% (for CL2), 100% (for CL3), 85% (for CL4), and
88% (for CL5).
more, based on FAB mass spectroscopy and elemental analysis,
the molecular formula of CL2 was determined to be
[Cu(L2)](PF6). Other copper(a) complexes (CL1 ([Cu(L1)]-
(PF6)), CL3 ([Cu(L3)](PF6)), CL4 ([Cu2(L4)2](PF6)2), and CL5
([Cu2(L5)2](PF6)2)) were also obtained in a similar manner in
87%, 100%, 85%, and 88% yields, respectively. Figure 3 shows
the circular dichroism spectra of CL4 and CL5, respectively. The
spectra are mirror images of each other. Additionally, a
significant change in the optical rotations of the complexes in
chloroform (CL4, ½ꢂꢃD ꢂ446:9ꢁ (c 1.62); CL5, ½ꢂꢃD þ418:4ꢁ (c
1.47)) implies that the reaction of ligands L4 and L5 with the
copper(a) ions proceeded enantioselectively to afford enantio-
merically pure complexes. The generation of dinuclear copper(a)
complexes CL4 and CL5 implies that the substituent effect of the
ligand plays an important role in the self-assembly of the
copper(a) complex. Thus, wecan imagine thatwhena ligand with
a less bulky substituent is used, a mononuclear copper(a) complex
is obtained, and when a ligand with a bulky subsitutent is used, a
dinuclear copper(a) complex is obtained.
Structure of the Copper(a) Complexes. We attempted to

T. Kawano et al.
Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
791
Fig. 1. The 1H NMR spectra (400 MHz, CD2Cl2) of (a) the
ligand (L2) and (b) the copper(a) complex (CL2).
prepare single crystals of complexes to investigate the structure of
the copper(a) complexes obtained in this study by X-ray
crystallography. Although we could not obtain single crystals
of CL1 and CL2 due to their poor crystallinity, the conversion of
the counter ion (PF6ꢂ) of copper(a) complex CL2 to perchlorate
(ClO4ꢂ) enabled usꢂ to prepare single crystals of copper(a)
complex with ClO4 (CL20). X-ray quality single crystals of
CL20, CL3, CL4, and CL5 were obtained by recrystallization
from CH2Cl2 by the slow diffusion of hexane vapor (for CL20),
acetone (for CL3), and methanol (for CL4 and CL5),
respectively. The crystal structures of CL20 and CL3 are shown
in Fig. 4.12{14 The copper(a) complexes CL20 and CL3 consist of
one ligand, one two-coordinate copper(a) ion, and one counter
ion. Inthe case ofCL20, the ligand coordinates copper(a) ions ina
trans-chelating mode (Fig. 4a). The average dihedral angle
between the aromatic rings in CL20 is 3.63ꢁ, indicative of the
formation of a planar complex. The bond length of Cu–N is 1.935
Fig. 2. (a) Spectrophotometric titration of L2 with Cu-
(CH3CN)4PF6 in CH2Cl2. (b) The changes in absorbance
analyzed by the mole ratio methods at 358 nm.
ꢁ
0
ꢁ
A and the biteangle ofN–Cu–N is170.28(7) . CL2 isthereforea
ꢂ
mononuclear copper(a) chelate complex. The ClO4 anion
adopts a position nearly perpendicular to the N–Cu–N axis. The
distance between the copper(a) ion and the adjacent oxygen atom
ꢂ
ꢁ
of the ClO4 anion is 2.43 A, indicative of the presence of a
relatively strong interaction. The crystal structure of the cation of
CL3 also had a planar structure similar to that of CL20 (Fig. 4b),
indicating that, in the case of our complexes, no difference
ꢂ
ꢂ
between PF6 and ClO4 affects the cation structure. The
distance between the copper(a) ion and the hexafluorophosphate
ꢂ
ꢂ
ꢁ
anion(PF6 )ofCL3is2.8A, implyingaweakinteractionofPF6
with the copper(a) ion. The two aromatic rings in the terminal
substituent of L3 are almost perpendicular (92.78ꢁ) to each other.
Furthermore, based on the 1H NMR spectrum and elemental
analysis of CL1, it can be determined that CL1 is also a
mononuclear copper(a) chelate complex. In contrast, the
structural analysis showed CL4 and CL5 to be [Cu2(L4)2]-
Fig. 3. CD spectra of CL4 and CL5 in chloroform.

792 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Substituent Effect in the Self-Assembly
Fig. 4. ORTEP representations of (a) CL20 and (b) CL3. Counter ions are omitted for clarity.
determined to be triclinic P1, which is in a chiral space group.
Each copper(a) ion of CL4 has a distorted tetrahedral (N2O2)
coordination. The bond length between the copper(a) ion and the
ꢁ
nitrogen atom of the pyridine ring is in the range of 1.91–2.03 A,
and the bond angles between N–Cu(a)–N are 138.4ꢁ and 142.7ꢁ.
A slight bending of the triple bond (bond angle: 173ꢁ) is also
observed. Oxygen atoms weakly coordinate to the copper(a) ion
ꢁ
(bond length: 2.25 A). The two ligands of CL4 are stacked
coplanar above each other, with an interplane distance of
ꢁ
approximately 3.5 A, indicative of the presence of a p–p
interaction. In one ligand of CL4, the pyridyl and the remaining
1-ethynyl-2-(2-pyridylethynyl)phenyl binding domains are twis-
ted with respect to each other (average twist angle: 84.5ꢁ); the
coordination of the two ligands with the two copper(a) ions
therefore produces a hollow cavity. This finding clearly demon-
strates that the steric hindrance between the terminal bulky
substituents in the ligand has a large effect on the self-assembly of
the copper(a) complex.
DSC Traces for the Thermal Cyclizations of Ligand and
Copper(a) Complex. The ligands and the copper(a) complexes
in this study possess an endiyne skeleton. To probe the possible
thermal reactivity of our system, we examined their behavior by
differential scanning calorimetry (DSC). Figure 6 illustrates the
DSC traces for the thermal cyclization of the ligand L4 and the
copper(a) complexes CL1 and CL4. Ligand L4 exhibits a sharp
endothermic peak at about 118 ꢁC, followed by a broad
exothermic peak at above 300 ꢁC. On the other hand, complex
CL1 exhibits only a broad exothermic peak at above 300 ꢁC, and
complex CL4 exhibits a sharp endothermic peak at about 250 ꢁC,
ꢁ
followed by a broad exothermic peak at about 275 C. This
indicates that ligand L4 and mononuclear chelate complex CL1
are more thermally stable than dinuclear complex CL4, and that
the thermal cyclization of CL4 may proceed between two ligands
which compose complex CL4.
Behavior of the Copper(a) Complexes in Solution. It was
thought that, from a structural point of view, the concentration-
dependent behavior of the copper(a) complexes mentioned above
should be observed in a particular copper(a) complex. To
investigatethispoint, wemeasuredthe1H NMRspectra ofCL3 at
a dilute concentration (0.98 mM) (1 M = 1 mol dmꢂ3) and a
higher concentration (16 mM). As shown in Fig. 7, The 1H NMR
Fig. 5. ORTEP representations of CL4 and CL5 (a) from a
top view of CL4, (b) from a side view of CL4, and (c) from a
side view of CL5. Counter ions and hydrogen atoms are
omitted for clarity.
15
16
(PF6)2 and [Cu2(L5)2](PF6)2 (Fig. 5). As shown in Fig. 5,
CL4 consists of two copper(a) ions, two ligands, and two
uncoordinated counterions, and is structured as a dinuclear
copper(a) molecular rectangular box. The structure of CL5 is a
mirror image of CL4. The crystal system of CL4 and CL5 was

T. Kawano et al.
Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
793
Fig. 6. DSC traces for the thermal cyclization of L4, CL1,
and CL4.
Fig. 8. The abundance of complexes (a) CL3 and (b) CL2
under several concentration conditions in CH2Cl2. The
abundance of the mononuclear complex and the dinuclear
copper(a) complex, are marked with a white circle and a
black square, respectively.
generated as the main product at concentrations above that of a
22 mM solution of CL3 (Fig. 8a). CL2 showed behavior similar
to that of CL3, though the main product was a mononuclear
copper(a) complex at concentrations below 16 mM.17 On the
otherhand, no newpeakswereobservedinthe1H NMR spectra of
CL1 at concentrations below 4.2 mM.18 In the case of CL4 and
CL5, no new peaks were observed at concentrations in the range
of 0.35–20 mM.
A proposed mechanism for the self-assembly of copper(a)
complexes in this study is presented in Scheme 3. The
coordination of the ligand (L) with the copper(a) ion first gives
ꢀ
a monodentate copper(a) complex (CL ) as a reaction
ꢀ
chelate-closing reaction occurs immediately to give a mono-
intermediate. If the ligand in CL has a small substituent, a
ꢀ
has a bulky substituent, steric hindrance between the two
Fig. 7. The 1H NMR spectra of CL3 (a) at a dilute concen-
tration (0.98 mM) and (b) at a higher concentration (16
mM).
nuclear copper(a) chelate complex (CLa). If the ligand in CL
substituents prevents a mononuclear copper(a) chelate complex
ꢀ
frombeinggenerated. Consequently,dimerizationofCL occurs
to afford a dinuclear copper(a) complex CLb. If a ligand with a
substituent less bulky in size is used, two types of copper(a)
complexes, CLa and CLb, are in an equilibrium state, depending
on the concentration of the reaction solution, and then the more
thermodynamically stable complex would be obtained exclu-
sively.
measurement of CL3 at a higher concentration resulted in the
appearance of new peaks, which implies the formation of a
copper(a) complexdifferent fromCL3. Thisnew complexshould
be a dinuclear copper(a) complex. This behavior was also
observed in CL2. To clarify the concentration-structure relation-
ship of copper(a) complexes CL2 and CL3, we examined the
abundance of complexes under several concentration conditions
(Fig. 8). In the case of CL3, the abundance of the mononuclear
copper(a) complex was found to decrease with increases in the
concentration, and a dinuclear copper(a) complex is then
Conclusion
In conclusion, we have demonstrated that the coordination of
1,2-bis(2-pyridylethynyl)benzenes with copper(a) ions proceeds

794 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Substituent Effect in the Self-Assembly
Scheme 3. A proposed mechanism for the self-assembly of the copper(a) complexes (CLa and CLb) in this study.
2-Bromo-6-(methoxymethyl)pyridine (3).10 To a suspension
smoothly to yield mononuclear copper(a) chelate complexes or
of sodium hydride (60% in mineral oil, 0.729 g, 30.9 mmol) in THF
(30 mL) was added dropwise a solution of 2-bromo-6-(hydroxyme-
thyl)pyridine (2) (4.87 g, 25.9 mmol) in THF (30 mL) at 0 ꢁC. The
reaction mixture was stirred at the same temperature for 1 h, and then
methyl iodide (5.0 mL, 80.3 mmol) was added. After being stirred at
the same temperature for 1 h, the reaction mixture was quenched with
cold saturated aqueous NH4Cl and extracted with AcOEt. The
organic layer was washed with H2O and brine, successively, and then
dried over anhydrous MgSO4. After removal of the solvent, the oily
residue was purified by column chromatography (silica gel, hexane–
AcOEt) to give 3 (5.42 g, 97%) as a pale yellow oil: 1H NMR (400
MHz, CDCl3) ꢁ 7.57 (t, J ¼ 7:7 Hz, 1H), 7.41 (d, J ¼ 7:8 Hz, 1H),
7.39 (d, J ¼ 8:0 Hz, 1H), 4.56 (s, 2H), 3.48 (d, 3H).
dinuclear copper(a) molecular rectangular boxes in excellent
yields, depending on the size of the substituent. Metal complexes
interconverting between monomers and self-assembled oligo-
mers by an input of external information would provide us with a
new material for the further development of metallosupramole-
cular chemistry.
Experimental
General.
All reactions were carried out under an argon
atmosphere with dry solvents under anhydrous conditions unless
otherwise noted. Solvents and reagents were purified by literature
methods when necessary.19 All melting points were determined on a
Yanagimoto micro melting point apparatus (Yanaco MP-500D) and
are uncorrected. Infrared (IR) spectra were recorded on a Perkin-
Elmer system 2000 FT-IR spectrometer. UV absorption spectra were
obtainedusingaHitachi260-30spectrophotometer. 1H NMRspectra
were recorded on a JEOL JNM-LA400 (400 MHz) spectrometer;
chemical shifts (ꢁ) are reported in parts per million relative to
tetramethylsilane (TMS). The splitting patterns are designated as s,
singlet; d, doublet; t, triplet; q, quartet; m, multiplet; br, broad; dsp,
double of septets. Mass spectra (MS) were recorded on a JEOL JMS-
600 mass spectrometer. Elemental analyses were performed by the
Material Analysis Center of the Institute of Scientific and Industrial
Research, Osaka University. Optical rotations were measured with a
Perkin-Elmer 241 polarimeter. Circular dichroism spectroscopy was
performed on a JASCO J-725 spectropolarimeter. DSC curves were
recorded on a SHIMADZU DSC-50 differential scanning calorim-
eter. Column chromatographywas performedonMerck silica gel60.
1,2-Bis(ethynyl)benzene (1)8 and 2-bromo-6-(hydroxymethyl)pyri-
dine (2)9;10 were prepared according to the literature procedure.
2-Bromo-6-(methanesulfonylmethyl)pyridine (4). To a solu-
tion of 2-bromo-6-(hydroxymethyl)pyridine (2) (3.14 g, 16.7 mmol)
in dry THF (70 mL) were added triethylamine (3.4 mL, 24.6 mmol)
and 4-(dimethylamino)pyridine (0.102 g, 0.835 mmol) at room
temperature. To the resulting solution was added dropwise
ꢁ
methanesulfonyl chloride (2.0 mL, 25.8 mmol) at ꢂ40 C. After
being stirred at the same temperature for 2.5 h, the reaction mixture
was quenched with saturated aqueous NH4Cl and extracted with
AcOEt. The organic layer was washed with saturated aqueous
NaHCO3, H2O, and brine, successively, and then dried over
anhydrous MgSO4. After removal of the solvent, an oily residue
was purified by column chromatography (silica gel, hexane–AcOEt)
to give 4 (4.23 g, 95%) as a colorless oil: 1H NMR (400 MHz, CDCl3)
ꢁ 7.62 (t, J ¼ 7:8 Hz, 1H), 7.49 (d, J ¼ 7:6 Hz, 1H), 7.45 (d, J ¼ 7:6
Hz, 1H), 5.29 (s, 2H), 3.13 (s, 3H); IR (neat) 3000, 2910, 1570, 1545,
1425, 1395, 1345, 1160, 1110, 955, 820 cmꢂ1; FABMS (NBA) m=z
266 [(M + H)þ]; Found: C, 31.26; H, 2.92; N, 5.14; Br, 30.16; S,
11.91%. Calcd for C7H8BrNO3S: C, 31.59; H, 3.03; N, 5.26; Br,

T. Kawano et al.
Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
795
30.03; S, 12.05%.
palladium (0.060 g, 0.052 mmol) and diethylamine (10 mL) was
addeddropwiseasolutionof1,2-bis(ethynyl)benzene1(0.200g,1.59
mmol) in diethylamine (5 mL) at room temperature. After being
2-Bromo-6-(iodomethyl)pyridine (5). To a solution of 4 (3.93
g, 14.8 mmol) in acetone (150 mL) was added NaI (8.87 g, 59.2
mmol)atroomtemperature. Afterbeing heated underreflux for 5.5h,
the reaction mixture was cooled to room temperature, and then
filtered through a pad of Celite. The solvent was evaporated to
dryness under reduced pressure, and then the resulting oily residue
was dissolved with AcOEt. The organic layer was washed with
saturated aqueous Na2S2O3, H2O, and brine, successively, and then
dried over anhydrous MgSO4. After removal of the solvent, the oily
residue was purified by column chromatography (silica gel, hexane–
AcOEt) to give 5 (4.31 g, 98%) as pale yellow crystals: mp 56.5–58.5
ꢁC (dec); 1H NMR (400 MHz, CDCl3) ꢁ 7.50 (t, J ¼ 7:8 Hz, 1H),
7.36 (d, J ¼ 7:6 Hz, 1H), 7.35 (d, J ¼ 7:8 Hz, 1H), 4.47 (s, 2H); IR
(NaCl) 3050, 1580, 1560, 1410, 1140, 880 cmꢂ1; FABMS (NBA)
m=z 298 [(M + H)þ]; Found: C, 24.18; H, 1.59; N, 4.53; Br, 26.57; I,
42.79%. Calcd for C6H5BrIN:C, 24.19;H, 1.70;N, 4.70;Br, 26.82;I,
42.06%.
ꢁ
stirred at 80 C for 12 h, the reaction mixture was cooled to room
temperature, and thenfiltered through apad ofCelite. The filtrate was
evaporated to dryness under reduced pressure to give an oily residue.
The oily residue was dissolvedwithAcOEt, and the resulting solution
was washed with saturated aqueous NH4Cl, H2O, and brine,
successively, and then dried over MgSO4. After removal of the
solvent, the oily residue was purified by column chromatography
(silica gel, AcOEt–C6H6) to give L1 (0.320 g, 72%) as colorless
plates: mp 112.8–114.1 ꢁC; 1H NMR (400 MHz, CDCl3) ꢁ 8.64 (dt,
J ¼ 1:2, 4.9 Hz, 2H), 7.70–7.67 (m, 4H), 7.66 (dd, J ¼ 5:8, 3.4 Hz,
2H), 7.38 (dd, J ¼ 5:8, 3.3 Hz, 2H), 7.26 (ddd, J ¼ 6:3, 4.9, 2.4 Hz,
2H); IR (KBr) 3060, 2220, 1580, 1485, 755, 735 cmꢂ1; UV (CH2Cl2)
ꢃmax (log ") 315 (4.36), 289 (4.56), 261 (4.57) nm; FABMS (NBA)
m=z 281 ½ðM þ HÞþꢃ; Found: C, 85.38; H, 4.31; N, 9.76%. Calcd for
C20H12N2: C, 85.69; H, 4.31; N, 9.99%.
2-Bromo-6-(phenoxymethyl)pyridine (6). To a suspension of
sodium hydride (60% in mineral oil, 0.504 g, 21.0 mmol) in THF (25
mL) was added dropwise a solution of phenol (1.83 g, 19.4 mmol) in
THF (25 mL) at 0 ꢁC. The reaction mixture was stirred at the same
temperature for 0.5 h, and then a solution of 5 (2.50 g, 8.39 mmol) in
THF (25 mL) was added. After being stirred at room temperature for
2 h, the reaction mixture was quenched with cold saturated aqueous
NH4Cl and extracted with AcOEt. The organic layer was washed
with H2O and brine, successively, and then dried over anhydrous
MgSO4. After removal of the solvent, the oily residue was purifiedby
column chromatography (silica gel, hexane–C6H6) to give 6 (2.07 g,
93%) as colorless needles: mp 63.2–63.9 C; H NMR (400 MHz,
CDCl3) ꢁ 7.58 (t, J ¼ 7:7 Hz, 1H), 7.51 (d, J ¼ 6:8 Hz, 1H), 7.42 (d,
J ¼ 7:6 Hz, 1H), 7.30 (t, 2H), 6.99 (t, 1H), 6.96 (d, 2H), 5.19 (s, 2H);
IR (KBr) 3040, 2905, 2860, 1600, 1555, 1500, 1445, 1405, 1250,
1075, 790 cmꢂ1; FABMS (NBA) m=z 265 [(M + H)þ]; Found: C,
54.31; H, 3.70; N, 5.20; Br, 30.11%. Calcd for C12H10BrNO: C,
54.57; H, 3.82; N, 5.30; Br, 30.25%.
2-Bromo-6-(L-menthyloxymethyl)pyridine (7). This com-
pound was prepared from 5 and L-menthol according to the method
used for the preparation of 6. Colorless oil; yield 99%; ½ꢂꢃD ꢂ73 (c
1.74, CHCl3); 1H NMR (400 MHz, CDCl3) ꢁ 7.53 (dd, J ¼ 7:6, 7.8
Hz, 1H), 7.45 (d, J ¼ 7:6 Hz, 1H), 7.33 (d, J ¼ 7:8 Hz, 1H), 4.74 (d,
J ¼ 13:9 Hz, 1H), 4.49 (d, J ¼ 13:9 Hz, 1H), 3.21 (dt, J ¼ 4:1, 10.5
Hz, 1H), 2.26 (tdd, J ¼ 2:7, 6.8, 10.5 Hz, 1H), 2.14 (br d, J ¼ 7:1 Hz,
1H), 1.70–1.58 (m, 2H), 1.44–1.26 (m, 2H), 1.05–0.77 (m, 9H), 0.73
(d, J ¼ 7:1 Hz, 3H); IR (neat) 2960, 2930, 2850, 1590, 1560, 1420,
1130, 990, 850, 795 cmꢂ1; FABMS (NBA) m=z 327 [(M + H)þ];
Found: C, 58.97; H, 7.30; N, 4.11; Br, 24.50%. Calcd for
C16H24BrNO: C, 58.91; H, 7.41; N, 4.29; Br, 24.49%.
1,2-Bis[(6-methoxymethyl-2-pyridyl)ethynyl]benzene (L2).
This compound was prepared from 1 and 3 according to the method
used for the preparation of L1. Pale yellow solids; yield 92%; mp
ꢁ
1
38.8–41.5 C; H NMR (400 MHz, CDCl3) ꢁ 7.70 (t, J ¼ 7:8 Hz,
2H), 7.65 (dd, J ¼ 5:8, 3.2 Hz, 2H), 7.62 (d, J ¼ 7:8 Hz, 2H), 7.43 (d,
J ¼ 7:8 Hz, 2H), 7.37 (dd, J ¼ 5:7, 3.3 Hz, 2H), 4.63 (s, 4H), 3.50 (s,
6H); IR (KBr) 2820, 2210, 1580, 1570, 1485, 1455, 1115, 800, 760
cmꢂ1; UV (CH2Cl2) ꢃmax (log ") 318 (4.34), 293 (4.55), 262 (4.53)
nm; FABMS (NBA) m=z 369 ½ðM þ HÞþꢃ; Found: C, 78.35; H, 5.41;
N, 7.62%. Calcd for C24H20N2O2: C, 78.24; H, 5.47; N, 7.60%.
1,2-Bis[(6-phenoxymethyl-2-pyridyl)ethynyl]benzene (L3).
This compound was prepared from 1 and 6 according to the method
used for the preparation of L1. Colorless needles; yield 95%; mp
122.1–122.5ꢁC;1H NMR(400MHz,CDCl3)ꢁ7.68 (dd, J ¼ 6:0, 3.2
Hz, 2H), 7.68–7.64 (m, 4H), 7.50 (dd, J ¼ 7:1, 2.0 Hz, 2H), 7.39 (dd,
J ¼ 5:7, 3.3 Hz, 2H), 7.30 (t, J ¼ 8:1 Hz, 4H), 6.99–6.96 (m, 6H),
5.25 (s, 4H); IR (KBr) 3055, 2900, 2860, 2210, 1600, 1570, 1500,
1445, 1245, 1055, 795, 765 cmꢂ1; UV (CH2Cl2) ꢃmax (log ") 319
(4.05), 293 (4.27), 263 (4.23) nm; FABMS (NBA) m=z 493 [(M +
H)þ]; Found: C, 82.69; H, 4.71; N, 5.81%. Calcd for C34H24N2O2: C,
82.91; H, 4.91; N, 5.69%.
ꢁ
1
1,2-Bis[(6-L-menthoxymethyl-2-pyridyl)ethynyl]benzene
(L4). This compound was prepared from 1 and 7 according to the
method used for the preparation of L1. Colorless plates; yield 68%;
ꢁ
1
mp 114.7–115.4 C; ½ꢂꢃD ꢂ69:1 (c 1.94, CHCl3); H NMR (400
MHz, CDCl3) ꢁ 7.67 (t, J ¼ 7:7 Hz, 2H), 7.65 (dd, J ¼ 5:5, 3.5 Hz,
2H), 7.58 (d, J ¼ 7:1 Hz, 2H), 7.49 (d, J ¼ 7:3 Hz, 2H), 7.36 (dd,
J ¼ 5:9, 3.4 Hz, 2H), 4.82 (d, J ¼ 13:7 Hz, 2H), 4.59 (d, J ¼ 13:7
Hz, 2H), 3.26 (dt, J ¼ 4:0, 10.6 Hz, 2H), 2.32 (dsp, J ¼ 2:7, 7.0 Hz,
2H), 2.20 (brd, J ¼ 12:1 Hz, 2H), 1.69–1.64 (m, 4H), 1.44–1.31 (m,
4H), 1.06–0.83 (m, 6H), 0.94 (d, J ¼ 2:7 Hz, 6H), 0.92 (d, J ¼ 3:2
Hz, 6H), 0.76 (d, J ¼ 7:1 Hz, 6H); IR (KBr) 2955, 2920, 2210, 1565,
1455, 1115, 765 cmꢂ1; UV (CH2Cl2) ꢃmax (log ") 319 (4.39), 293
(4.61), 262 (4.57) nm; FABMS (NBA) m=z 617 ½ðM þ HÞþꢃ; Found:
C, 81.55; H, 8.52; N, 4.39%. Calcd for C42H52N2O2: C, 81.78; H,
8.50; N, 4.54%.
2-Bromo-6-(D-menthyloxymethyl)pyridine (8). This com-
pound was prepared from 5 and D-menthol according to the method
used for the preparation of 6. Colorless oil; yield 94%; ½ꢂꢃD þ63:9 (c
2.21, CHCl3); 1H NMR (400 MHz, CDCl3) ꢁ 7.53 (dd, J ¼ 7:6, 7.8
Hz, 1H), 7.45 (d, J ¼ 7:6 Hz, 1H), 7.33 (d, J ¼ 7:8 Hz, 1H), 4.74 (d,
J ¼ 13:9 Hz, 1H), 4.49 (d, J ¼ 13:9 Hz, 1H), 3.21 (dt, J ¼ 4:1, 10.5
Hz, 1H), 2.26 (tdd, J ¼ 2:7, 6.8, 10.5 Hz, 1H), 2.14 (br d, J ¼ 7:1 Hz,
1H), 1.70–1.58 (m, 2H), 1.44–1.26 (m, 2H), 1.05–0.77 (m, 9H), 0.73
(d, J ¼ 7:1 Hz, 3H); IR (neat) 2960, 2930, 2850, 1590, 1560, 1420,
1130, 990, 850, 795 cmꢂ1; FABMS (NBA) m=z 327 ½ðM þ HÞþꢃ;
Found: C, 58.99; H, 7.35; N, 4.18; Br, 24.52%. Calcd for
C16H24BrNO: C, 58.91; H, 7.41; N, 4.29; Br, 24.49%.
1,2-Bis[(6-D-menthoxymethyl-2-pyridyl)ethynyl]benzene
(L5). This compound was prepared from 1 and 8 according to the
method used for the preparation of L1. Colorless plates; yield 72%;
ꢁ
1
mp 114.7–115.4 C; ½ꢂꢃD þ66:9 (c 1.57, CHCl3); H NMR (400
MHz, CDCl3) ꢁ 7.67 (t, J ¼ 7:7 Hz, 2H), 7.65 (dd, J ¼ 5:5, 3.5 Hz,
2H), 7.58 (d, J ¼ 7:1 Hz, 2H), 7.49 (d, J ¼ 7:3 Hz, 2H), 7.36 (dd,
J ¼ 5:9, 3.4 Hz, 2H), 4.82 (d, J ¼ 13:7 Hz, 2H), 4.59 (d, J ¼ 13:7
Hz, 2H), 3.26 (dt, J ¼ 4:0, 10.6 Hz, 2H), 2.32 (dsp, J ¼ 2:7, 7.0 Hz,
1,2-Bis(2-pyridylethynyl)benzene (L1).4a To a mixture of 2-
bromopyridine (0.571 g, 3.61 mmol), tetrakis(triphenylphosphine)-

796 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Substituent Effect in the Self-Assembly
2H), 2.20 (brd, J ¼ 12:1 Hz, 2H), 1.69–1.64 (m, 4H), 1.44–1.31 (m,
4H), 1.06–0.83 (m, 6H), 0.94 (d, J ¼ 2:7 Hz, 6H), 0.92 (d, J ¼ 3:2
Hz, 6H), 0.76 (d, J ¼ 7:1 Hz, 6H); IR (KBr) 2955, 2920, 2210, 1565,
1455, 1115, 765 cmꢂ1; UV (CH2Cl2) ꢃmax (log ") 319 (4.39), 293
(4.61), 262 (4.57) nm; FABMS (NBA) m=z 617 [(M + H)þ]; Found:
C, 81.80; H, 8.51; N, 4.33%. Calcd for C42H52N2O2: C, 81.78; H,
8.50; N, 4.54%.
Copper(a) Complex CL1: [Cu(L1)](PF6). To a solution of
tetrakis(acetonitrile)copper(a) hexafluorophosphate (0.293 g, 0.786
mmol) in dichloromethane (30 mL) was added dropwise a solution of
L1 (0.218 g, 0.778 mmol) in dichloromethane (6.0 mL) at room
temperature. After being stirred at the same temperature for 12 h, the
reaction solution was evaporatedtodrynessunderreducedpressureto
give crude yellow crystals. Recrystallization of the crude crystals
from dichloromethane–hexane gave the pure complex CL1 (0.340 g,
87%)as yellow powders: mp>300 ꢁC; 1H NMR (400 MHz, CD2Cl2)
ꢁ 8.96 (d, J ¼ 5:4 Hz, 2H), 8.00 (t, J ¼ 7:8 Hz, 2H), 7.81 (d, J ¼ 8:0
Hz, 2H), 7.63 (dd, J ¼ 5:7, 3.2 Hz, 2H), 7.63 (dd, J ¼ 7:8, 5.4 Hz,
2H), 7.44 (dd, J ¼ 5:7, 3.3 Hz, 2H); IR (KBr) 3120, 2225, 1600,
1495, 840, 765 cmꢂ1; UV (CH2Cl2) ꢃmax (log ") 354 (4.36), 331
(4.43), 310 (4.74), 277 (4.61), 256 (4.61) nm; FABMS (NBA) m=z
343 ½ðM ꢂ PF6Þþꢃ; Found: C, 49.35; H, 2.69; N, 5.59; F,23.22; P,
6.22%. Calcd for C20H12CuF6N2P: C, 49.14; H, 2.47; N, 5.73; F,
23.32; P, 6.34%.
Copper(a) Complex CL2: [Cu(L2)](PF6). This compound was
synthesized from L2 and Cu(CH3CN)4(PF6) according to the method
used for the preparation of CL1. Yellow solids; yield 90%; mp 180
ꢁC (dec); 1H NMR (400 MHz, CD2Cl2) ꢁ 8.08 (t, J ¼ 7:8 Hz, 2H),
7.85 (d, J ¼ 7:8 Hz, 2H), 7.80 (dd, J ¼ 5:8, 3.3 Hz, 2H), 7.61 (d,
J ¼ 8:0 Hz, 2H), 7.59 (dd, J ¼ 5:9, 3.2 Hz, 2H), 4.89 (s, 4H), 3.36 (s,
6H); IR (KBr) 2940, 2835, 2215, 1600, 1565, 1485, 1455, 1115, 840,
800, 770 cmꢂ1; UV(CH2Cl2) ꢃmax (log ") 358(4.12), 333(4.23), 314
(4.54), 282 (4.39), 261 (4.45) nm; FABMS (NBA) m=z 431
½ðM ꢂ PF6Þþꢃ; Found: C, 49.70; H, 3.42; N, 4.78; F, 19.69; P,
5.24%. Calcd for C24H20CuF6N2O2P: C, 49.96; H, 3.49; N, 4.86; F,
19.76; P, 5.37%.
Copper(a) Complex CL3: [Cu(L3)](PF6). This compound was
synthesized from L3 and Cu(CH3CN)4(PF6) according to the method
used for the preparation of CL1. Yellow blocks; yield 100%; mp
100.6–101.9 ꢁC; 1H NMR (400 MHz, CD2Cl2) ꢁ 8.13 (t, J ¼ 7:8 Hz,
2H), 7.90 (d, J ¼ 7:8 Hz, 2H), 7.80 (dd, J ¼ 5:8, 3.2Hz, 2H), 7.65 (d,
J ¼ 7:8 Hz, 2H), 7.60 (dd, J ¼ 5:8, 3.2 Hz, 2H), 7.25 (t, 4H), 7.03 (t,
4H), 6.77 (d, 4H), 5.31 (s, 2H); IR (KBr) 3075, 2935, 2210, 1600,
1570, 1490, 1455, 1220, 1035, 840, 800, 755 cmꢂ1; UV (CH2Cl2)
½ðM ꢂ PF6Þþꢃ; Found: C, 61.13; H, 6.26; N, 3.46; F, 13.77; P, 3.69%.
CalcdforC84H104Cu2F12N4O4P2:C,61.12;H,6.35;N,3.39;F, 13.81;
P, 3.75%.
Copper(a) Complex CL5: [Cu2(L5)2](PF6)2. This compound
was synthesized from L5 and Cu(CH3CN)4(PF6) according to the
method used for the preparation of CL1. Yellow blocks; yield 88%;
mp 241 ꢁC (dec); ½ꢂꢃD ꢂ418:4 (c 1.47, CHCl3); 1H NMR (400 MHz,
CD2Cl2) ꢁ 8.10 (t, J ¼ 7:8 Hz, 4H), 7.84 (d, J ¼ 7:8 Hz, 4H), 7.80
(dd, J ¼ 5:6, 3.4 Hz, 4H), 7.63 (d, J ¼ 7:6 Hz, 4H), 7.59 (dd,
J ¼ 5:7, 3.3 Hz, 4H), 5.20 (d, J ¼ 14:6 Hz, 4H), 4.82 (d, J ¼ 14:6
Hz, 4H), 3.06 (dt, J ¼ 4:0, 10.4 Hz, 4H), 2.45 (dsp, J ¼ 2:3, 7.0 Hz,
4H), 2.18 (brd, J ¼ 11:5 Hz, 4H), 1.60 (brd, J ¼ 11:0 Hz, 4H), 1.52
(brd, J ¼ 9:8 Hz, 4H), 1.38–1.22 (br, 8H), 1.11–1.05 (brt, J ¼ 10:8
Hz, 12H), 0.92 (d, J ¼ 6:6 Hz, 12H), 0.90–0.75 (m, 12H), 0.62 (d,
J ¼ 7:1 Hz, 12H);IR(KBr)2955,2925, 2215, 1565,1455, 1085, 840,
770 cmꢂ1; UV (CH2Cl2) ꢃmax (log ") 358 (4.52), 334 (4.62), 314
(4.96), 282 (4.77), 261 (4.87) nm; FABMS (NBA) m=z 1505
½ðM ꢂ PF6Þþꢃ; Found: C, 61.15; H, 6.24; N, 3.48; F, 13.79; P, 3.70%.
CalcdforC84H104Cu2F12N4O4P2:C,61.12;H,6.35;N,3.39;F, 13.81;
P, 3.75%.
Copper(a) Complex CL20: [Cu(L2)](ClO4). To a solution of
CL2 (0.355 g, 0.615 mmol) in acetone (18 mL) was added a solution
of tetrabutylammonium perchlorate (1.45 g, 4.39 mmol) in acetone
(12 mL) at room temperature. After being stirred at the same
temperature for 24 h, the reaction mixture was evaporated to dryness
under reduced pressure, and then the resulting residue was washed
with AcOEt. Recrystallization of the crude crystals from CH2Cl2–
hexane gave CL20 (0.128 g, 67%) as yellow blocks. mp > 200 ꢁC;
1H NMR (400 MHz, CD2Cl2) ꢁ 8.08 (t, J ¼ 7:8 Hz, 2H), 7.85 (d,
J ¼ 7:6 Hz, 2H), 7.80 (dd, J ¼ 5:8, 3.3 Hz, 2H), 7.62 (d, J ¼ 8:1 Hz,
2H), 7.59 (dd, J ¼ 5:7, 3.3 Hz, 2H), 4.92 (s, 4H), 3.37 (s, 6H); IR
(KBr) 2935, 2825, 2210, 1595, 1570, 1490, 1455, 1120, 805, 760, 620
cmꢂ1; UV (CH2Cl2) ꢃmax (log ") 358 (4.51), 334 (4.62), 314 (4.95),
282 (4.78), 261 (4.86) nm; FABMS (NBA) m=z 431 ½ðM ꢂ ClO4Þþꢃ;
Found: C, 54.03; H, 3.81; N, 5.20; Cl, 6.73%. Calcd for C24H20-
ClCuN2O6: C, 54.24; H, 3.79; N, 5.27; Cl, 6.67%. This compound
was also prepared directly from L2 and Cu(CH3CN)4ClO4.20
We thank the Material Analysis Center of ISIR-Sanken, Osaka
University for assisting us with elemental analysis.
References
1
J.-M. Lehn, ‘‘Supramolecular Chemistry—Concepts and
Perspectives,’’ VCH, Weinheim (1995).
a) ‘‘Transition Metals in Supramolecular Chemistry,’’ ed by
ꢃ
max (log ") 361 (4.09), 337 (4.23), 316 (4.57), 278 (4.40), 263 (4.47)
nm; FABMS (NBA) m=z 555 ½ðM ꢂ PF6Þþꢃ; Found: C, 58.04; H,
3.20; N, 4.28; F, 16.09; P, 4.30%. Calcd for C34H24CuF6N2O2P: C,
58.25; H, 3.45; N, 4.00; F, 16.26; P, 4.42%.
2
L. Fabbrizi and A. Poggi, Kluwer Academic Publishers, Dordrecht
(1994). b) A. F. Williams, C. Floriani, and A. E. Merbach,
‘‘Perspectives in Coordination Chemistry,’’ VCH, Weinheim
(1992).
Copper(a) Complex CL4: [Cu2(L4)2](PF6)2. This compound
was synthesized from L4 and Cu(CH3CN)4(PF6) according to the
method used for the preparation of CL1. Yellow blocks; yield 85%;
mp 240 ꢁC (dec); ½ꢂꢃD ꢂ446:9 (c 1.62, CHCl3); 1H NMR (400 MHz,
CD2Cl2) ꢁ 8.10 (t, J ¼ 7:8 Hz, 4H), 7.84 (d, J ¼ 7:8 Hz, 4H), 7.80
(dd, J ¼ 5:6, 3.4 Hz, 4H), 7.63 (d, J ¼ 7:6 Hz, 4H), 7.59 (dd,
J ¼ 5:7, 3.3 Hz, 4H), 5.20 (d, J ¼ 14:6 Hz, 4H), 4.82 (d, J ¼ 14:6
Hz, 4H), 3.06 (dt, J ¼ 4:0, 10.4 Hz, 4H), 2.45 (dsp, J ¼ 2:3, 7.0 Hz,
4H), 2.18 (brd, J ¼ 11:5 Hz, 4H), 1.60 (brd, J ¼ 11:0 Hz, 4H), 1.52
(brd, J ¼ 9:8 Hz, 4H), 1.38–1.22 (br, 8H), 1.11–1.05 (brt, J ¼ 10:8
Hz, 12H), 0.92 (d, J ¼ 6:6 Hz, 12H), 0.90–0.75 (m, 12H), 0.62 (d,
J ¼ 7:1 Hz,12H);IR(KBr)2955, 2925, 2215,1565, 1455, 1085,840,
770 cmꢂ1; UV (CH2Cl2) ꢃmax (log ") 358 (4.52), 334 (4.62), 314
(4.96), 282 (4.77), 261 (4.87) nm; FABMS (NBA) m=z 1505
3
For examples, see: a)B. J. Hollidayand C. A. Milkin, Angew.
Chem., Int. Ed., 40, 2022 (2001). b) J.-P. Collin, C. O. Dietrich-
Buchecker, P. Gavin˜a, M. C. Jimenez-Molero, and J.-P. Sauvage,
Acc. Chem. Res., 34, 477 (2001). c) L. R. MacGillivray and J. L.
Atwood, Angew. Chem., Int. Ed., 38, 1019 (1999). d) P. J. Stang and
B. Olenyuk, Angew. Chem., Int. Ed. Engl., 35, 732 (1996). e) M.
Fujita and K. Ogura, Bull. Chem. Soc. Jpn., 69, 1471 (1996). f) C. R.
Woods, M. Benaglia, F. Cozzi, and J. S. Siegel, Angew. Chem., Int.
Ed. Engl., 35, 1830 (1996). g) E. C. Constable, Tetrahedron, 48,
10013 (1992).
4
a) E. Bosch and C. L. Barnes, Inorg. Chem., 40, 3097 (2001).
b) Y.-Z. Hu, C. Chamchoumis, J. S. Grebowicz, and R. P. Thummel,

T. Kawano et al.
Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
797
Inorg. Chem., 41, 2296 (2002). c) J. E. Fiscus, S. Shotwell, R. C.
Layland, M. D. Smith, H.-C. zur Loye, and U. H. F. Bunz, Chem.
Commun., 2001, 2674.
5 T. Kawano, J. Kuwana, T. Shinomaru, C.-X. Du, and I. Ueda,
Chem. Lett., 2001, 1230.
T ¼ 223 K, R ðRwÞ ¼ 0:029 (0.032) for 4250 reflections with
I > 3:0ꢆðIÞ.
14 Crystal data for CL3: [Cu(L3)](PF6): C34H26CuF6N2O2P,
ꢂ
Mr ¼ 701:09, triclinic, space group P1 (no. 2), a ¼ 10:758ð1Þ,
ꢁ
b ¼ 15:027ð1Þ, c ¼ 9:5088ð9Þ A, ꢂ ¼ 96:895ð8Þ, ꢄ ¼ 95:639ð9Þ,
ꢁ
ꢁ 3
6 T. Kawano, J. Kuwana, C.-X. Du, and I. Ueda, Inorg. Chem.,
41, 4078 (2002).
ꢅ ¼ 90:749ð8Þ , V ¼ 1518:2ð3Þ A , Z ¼ 2, Dcalc ¼ 1:534 g cmꢂ3
,
T ¼ 293 K, R ðRwÞ ¼ 0:040 (0.040) for 5418 reflections with
I > 3:0ꢆðIÞ.
7
For examples, see: a) M. Mimura, T. Matsuo, T. Nakashima,
and N. Matsumoto, Inorg. Chem., 37, 3553 (1998). b) M. Albrecht,
Chem. Eur. J., 3, 1466 (1997). c) N. Matsumoto, M. Mimura, Y.
Sunatsuki, S. Eguchi, Y. Mizuguchi, H. Miyasaka, and T.
Nakashima, Bull. Chem. Soc. Jpn., 70, 2461 (1997).
15 Crystal data for CL4: [Cu2(L4)2](PF6)2: C84H104Cu2-
F12N4O4P2, Mr ¼ 1650:79, triclinic, space group P1 (No. 1),
ꢁ
a ¼ 13:707ð4Þ, b ¼ 14:891ð3Þ, c ¼ 12:030ð1Þ A, ꢂ ¼ 101:65ð2Þ,
ꢁ
ꢁ 3
ꢄ ¼ 115:08ð2Þ, ꢅ ¼ 97:66ð1Þ , V ¼ 2110:8ð2Þ A , Z ¼ 1, Dcalc
¼
8
S. Takahashi, Y. Kuroyama, K. Sonogashira, and N.
Hagihara, Synthesis, 1980, 627.
D. Cai, D. L. Hughes, and T. R. Verhoeven, Tetrahedron
1:30 g cmꢂ3, T ¼ 288 K, R ðRwÞ ¼ 0:054 (0.092) for 4679 reflec-
tions with I > 3:0ꢆðIÞ.
9
16 Crystal data for CL5: [Cu2(L5)2](PF6)2: C84H104Cu2F12-
N4O4P2, Mr ¼ 1650:79, triclinic, space group P1 (No. 1),
Lett., 37, 2537 (1996).
ꢁ
10 H. Tsukube, J. Uenishi, H. Higaki, K. Kikkawa, T. Tanaka,
S. Wakabayashi, and S. Oae, J. Org. Chem., 58, 4389 (1993).
11 J. Kubas, Inorg. Synth., 19, 90 (1979).
a ¼ 13:539ð4Þ, b ¼ 14:755ð2Þ, c ¼ 11:951ð2Þ A, ꢂ ¼ 101:70ð1Þ,
ꢁ
ꢁ 3
ꢄ ¼ 115:11ð1Þ, ꢅ ¼ 97:44ð2Þ , V ¼ 2053:8ð8Þ A , Z ¼ 1, Dcalc
¼
1:34 g cmꢂ3, T ¼ 198 K, R ðRwÞ ¼ 0:052 (0.053) for 5966 reflec-
12 All the X-ray diffraction data were collected on a Rigaku
AFC7R diffractometer with graphite monochromated Mo-Kꢂ
radiation and a rotating anode generator (for CL20 and CL3) or a
Rigaku RAXIS-IV imaging area detector with graphite monochro-
mated Mo Kꢂ radiation (for CL4). Calculations were carried out on
an SGI Indy using the teXsan21 crystallographic software package
from Molecular Science Corp. The structure was solved by direct
methods of SIR9222 and expanded using Fourier techniques. The
non-hydrogen atoms were refined anisotropically. The refinement
of the structure was performed by full-matrix least-squares
methods.
tions with I > 3:0ꢆðIÞ.
17 We were unable to measure 1H NMR spectra of CL2 at
concentration above 20 mM due to the low solubility of CL2.
18 We were unable to measure 1H NMR spectra of CL1 at
concentration above 4.2 mM due to the poor solubility of CL1.
19 D. D. Perrin and W. L. Armarego, ‘‘Purification of
Laboratory Chemicals,’’ 3rd ed, Pergamon, New York (1988).
20 B. J. Hathaway, D. G. Holah, and J. D. Postlewaite, J. Chem.
Soc., 1961, 3215.
21 ‘‘Single-Crystal Structure Analysis Software, Version 1.6,’’
Molecular Science Corp., The Woodlands, TX (1993).
22 M. C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo, G.
Polidori, R. Spagna, and D. Viterbo, J. Appl. Crystallogr., 22, 389
(1989).
13 Crystal data for CL20: [Cu(L2)](ClO4): C24H20ClCuN2O6,
ꢂ
Mr ¼ 531:43, triclinic, space group P1 (no. 2), a ¼ 10:276ð2Þ,
ꢁ
b ¼ 12:226ð2Þ, c ¼ 9:455ð1Þ A, ꢂ ¼ 96:52ð1Þ, ꢄ ¼ 91:81ð1Þ,
ꢁ
ꢁ 3
ꢅ ¼ 71:93ð1Þ , V ¼ 1121:9ð3Þ A , Z ¼ 2, Dcalc ¼ 1:573 g cmꢂ3
,