1364 Bull. Chem. Soc. Jpn. Vol. 80, No. 7 (2007)
Conformational Conversion of Copper Complexes
[Cu2(tpx)(µ-Cl)]+
Cl−
+
x[(CuCl)2(tpx)] + (1−x)[{Cu2(tpx)(µ-Cl)}+Cl−]
Scheme 5.
red for 1 day to afford a yellow precipitate of [(CuCl)2(tpx)] (1)
(45 mg, 0.061 mmol, 66%), which was collected by filtration and
washed with acetone. Orange single crystals suitable for X-ray
analysis were obtained from a solution of the complex in CH2Cl2
by slow diffusion of methanol at room temperature. Anal. Calcd
Conclusion
Dinuclear copper(I) complexes of a dinucleating polypyri-
dine ligand with either terminal, [(CuX)2(tpx)], or bridging
halogeno ligands, [Cu2(tpx)(ꢀ-X)](OTf), (X ¼ Cl, Br, and I)
were synthesized and structurally characterized. In solution,
the terminal halogeno complexes 1–3 were in equilibrium with
the corresponding bridging halogeno complexes 4þ–6þ, re-
spectively. 1H NMR spectroscopy showed that formation of
these bridging halogeno complexes is favored in the order
Cl > Br > I. The equilibrium was studied for the chloride de-
rivative using quantitative ESI-MS measurements, and from
these data, the equilibrium constant was estimated to be in
the range 2:8{4:8 ꢄ 105 Mꢃ1, which actually represents the
equilibrium between the solvated complex cations and total
of the terminal complexes and the ion pairs of the bridging
complex cations.
for Cu2Cl2:67C28:33H22:67N4S4 (1 1/3CH2Cl2): C, 44.25; H, 2.97;
ꢁ
N, 7.28%. Found: C, 44.23; H, 3.12; N, 7.28%. 1H NMR (300
MHz, CD2Cl2, 298 K): ꢃ 8.46 (4H, br, 6-H-pyridyl), 7.67 (4H,
br, 4-H-pyridyl), 7.51 (4H, br, 3-H-pyridyl), 7.15 (4H, br, 5-þH-
pyridyl), 2.36 (6H, s, CH3). MS (ESIþ): m=z ¼ 705 (½M ꢃ Clꢅ ).
Complexes 2 and 3 were synthesized in a similar manner as 1
using CuBr (24 mg, 0.200 mmol) or CuI (40 mg, 0.210 mmol),
instead of CuCl, in 99% (64 mg, 0.093 mmol) or 92% (86 mg,
0.092 mmol) yields, respectively. Single crystals suitable for X-
ray structure analyses were obtained from each solution of the
complexes by slow diffusion of methanol. Data for 2: Anal. Calcd
for Cu2Br2C28:5H23N4S4Cl (2 1/2CH2Cl2): C, 39.25; H, 2.66; N,
1
ꢁ
6.42%. Found: C, 39.27; H, 2.53; N, 6.53%. H NMR (300 MHz,
CD2Cl2, 298 K): ꢃ 8.45 (4H, br, 6-H-pyridyl), 7.61 (4H, br, 4-H-
pyridyl), 7.48 (4H, br, 3-H-pyridyl), 7.12 (4H, br, 5-H-þpyridyl),
2.36 (6H, br, CH3). MS (ESIþ): m=z ¼ 749 (½M ꢃ Brꢅ ). Data
Experimental
Materials. All solvents were purchased from Nacalai Tesque
for reactions and from Sigma-Aldrich Japan or Merck for the
measurements. All chemicals were purchased from Sigma-Aldrich
Japan, Wako Pure Chemicals, Nacalai Tesque, or Tokyo Chemical
Industry Co and used as received.
Measurements. 1H NMR spectra were recorded on a JEOL
Lambda 300 FT-NMR spectrometer, and chemical shifts were ref-
erenced to tetramethysilane. ESI mass spectrometry was per-
formed on an Applied Biosystem Mariner time-of-flight mass
spectrometer. UV–vis and emission spectra were measured on
JASCO V-570 and F-4500 spectrometers, respectively. Elemental
analyses were performed by the Analytical Research Service
Centre at Osaka City University on Perkin-Elmer 240C or
FISONS Instrument EA108 elemental analyzers.
for 3: Anal. Calcd for Cu2I2C28:25H22:5N4S4Cl0:5 (3 1/4CH2Cl2):
ꢁ
C, 35.91; H, 2.40; N, 5.93%. Found: C, 36.02; H, 2.32; N, 5.93%.
1H NMR (300 MHz, CD2Cl2): ꢃ 8.45 (4H, d, JH{H ¼ 0:9 Hz,
JH{H ¼ 1:7 Hz, JH{H ¼ 5:3 Hz, 6-H-pyridyl), 7.64 (4H, t, JH{H
¼
7:6 Hz, 4-H-pyridyl), 7.48 (4H, d, JH{H ¼ 7:6, 3-H-pyridyl),
7.12 (4H, t, JH{H ¼ 6:12, 5-H-pyridyl), 2.31 (6H, s, CH3). MS
(ESIþ): m=z ¼ 797 (½M ꢃ Iꢅþ).
Preparation of Bridged Halogeno Complexes, [Cu2(tpx)-
(ꢀ-X)](OTf) (X ¼ Cl (4OTf), Br (5OTf), and I (6OTf)).
A
solution of AgOTf (18 mg, 0.070 mmol) in methanol (2 mL) was
added to a solution of 1 (51 mg, 0.068 mmol) in CH2Cl2 (10 mL),
upon which the color changed from yellow to brown and then to
pale yellow. After stirring for 30 min, a white precipitate of AgCl
was filtered off, and the solution was concentrated to ca. 5 mL
under reduced pressure. Addition of diethyl ether afforded a
yellow powder of the chloro-bridged complex [Cu2(tpx)(ꢀ-Cl)]-
(OTf) (4OTf) in an 83% yield. Anal. Calcd for C29H22ClCu2F3-
N4O3S5: C, 40.77; H, 2.60; N, 6.56%. Found: C, 40.69; H, 2.56;
Preparation of 1,2,4,5-Tetrakis(pyridyl-2-thio)-p-xylene (tpx).
A mixture of 1,2,4,5-tetrabromo-p-xylene (5.00 g, 11.9 mmol),
NaOCH3 (7.08 g, 13.1 mmol), and pyridine-2-thiol (6.64 g, 59.8
mmol) in DMF (250 mL) was heated at 130 ꢂC under Ar atmo-
sphere for 20 h. Additional pyridine-2-thiol (6.75 g, 60.7 mmol)
was added, and the mixture was heated for additional 8 h. After
removal of the solvent, the residue was re-dissolved in CH2Cl2
(ca. 400 mL), and the solution was washed with H2O (ca. 200
mL) to remove unreacted pyridine-2-thiol and NaOCH3. Activat-
ed charcoal was added to the separated organic layer, the solution
was filtered, and then the solvent was evaporated. The crude prod-
uct was dissolved in a small amount of CH2Cl2 and addition of
diethyl ether (ca. 400 mL) afforded precipitation of pure product
as a pale yellow powder (3.50 g, 6.49 mmol, 55%). Anal. Calcd
for C28H22N4S4: C, 61.96; H, 4.09; N, 10.32%. Found:
C, 61.93; H, 4.00; N, 10.19%. 1H NMR (300 MHz, CD2Cl2): ꢃ
8.28 (4H, ddd, JH{H ¼ 0:9 Hz, JH{H ¼ 1:8 Hz, JH{H ¼ 4:4 Hz, 6-
H-pyridyl), 7.39 (4H, dt, JH{H ¼ 1:9 Hz, JH{H ¼ 7:8 Hz, 4-H-pyri-
N, 6.49%. 1H NMR (300 MHz, CD2Cl2): ꢃ 8.51 (4H, ddd, JH{H
0:8 Hz, JH{H ¼ 1:7 Hz, JH{H ¼ 5:4 Hz, H-2-pyridyl), 7.76 (4H, td,
¼
JH{H ¼ 1:8 Hz, JH{H ¼ 3:9 Hz, H-3-pyridyl), 7.63 (4H, dt, JH{H
¼
1:0 Hz, JH{H ¼ 8:1 Hz, H-5-pyridyl), 7.22 (4H, m, H-4-pyridyl),
2.58 (6H, s, CH3).
A similar reaction using complexes 2 and 3, instead of 1, gave
5OTf (56 mg, 0.067 mmol) and 6OTf (63 mg, 0.068 mmol) in 75
or 79% yields, respectively. Single crystals of each complex were
obtained by slow evaporation of solvent from methanolic solu-
tions. Data for 5OTf: Anal. Calcd for C29H22BrCu2F3N4O3S5:
C, 38.75; H, 2.47; N, 6.23%. Found: C, 38.82; H, 2.46; N,
1
6.30%. H NMR (300 MHz, CD2Cl2): ꢃ 8.52 (4H, JH{H ¼ 4:6 Hz,
6-H-pyridyl), 7.76 (4H, t, JH{H ¼ 7:8 Hz, 4-H-pyridyl), 7.62 (4H,
d, JH{H ¼ 7:8 Hz, 3-H-pyridyl), 7.23 (4H, t, JH{H ¼ 6:3 Hz, 4-H-
pyridyl), 2.29 (6H, s, CH3). Data for 6OTf: Anal. Calcd for
dyl), 6.47 (8H, m, 3-, 5-H-pyridyl), 2.64 (6H, s, CH3). HRMS
(ESIþ): m=z calcd for
565.0620. Found: 565.0617.
C
28
1H2214N432S423Na1 (½M þ Naꢅþ):
12
C30H24Cl2Cu2F3IN4O3S5 (6OTf CH2Cl2): C, 34.96; H, 2.35;
ꢁ
Preparation of Terminal Halogeno Complexes, [(CuX)2(tpx)]
(X ¼ Cl (1), Br (2), and I (3)). A mixture of CuCl (20 mg, 0.210
mmol) and tpx (50 mg, 0.093 mmol) in methanol (25 mL) was stir-
N, 5.44%. Found: C, 35.06; H, 2.37; N, 5.52%. 1H NMR (300
MHz, CD2Cl2): ꢃ 8.49 (4H, d, JH{H ¼ 5:1 Hz, 6-H-pyridyl),
7.75 (4H, t, JH{H ¼ 7:2 Hz, 4-H-pyridyl), 7.56 (4H, d, JH{H
¼
Nishioka, Takanori
