Highly Electrochemically Stable Dicopper(II) Metallacyclophanes
FULL PAPER
by filtration, washed thoroughly with water to remove the precipitate of
(Et3NH)2SO4, washed with diethyl ether, and dried under vacuum
(15.5 g, 80%). 1H NMR (C2D6SO): d=1.28 (t, 6H; 2ꢀCH3), 2.18 (s, 3H;
C6H3CH3), 4.23 (q, 4H; 2ꢀCH2O), 7.29 (d, 1H; 5-H of C6H3CH3), 7.58
(d, 1H; 4-H of C6H3CH3), 7.63 (s, 1H; 3-H of C6H3CH3), 10.32 (s, 1H; 1
Li
AHCTUNGTRENNUNG
4ACHTUNGTRENGU[N Cu2ACHTUGNTREN(NNGU Meppba)2]·7H2O (2b): An aqueous solution (10 mL) of Cu-
tion (50 mL) of Et2H2Meppba (1.6 g, 5.0 mmol) and LiOH·H2O (0.8 g,
20.0 mmol) with stirring at room temperature. The resulting deep-brown
solution was filtered, and the solvent was reduced under vacuum until a
solid appeared. The dark-brown solid was collected by filtration, washed
with acetone and diethyl ether, and dried under vacuum. Recrystalliza-
tion from an aqueous solution gave dark-brown prisms of 2b, which gave
crystals upon layering of methanol that were not suitable for single-crys-
tal X-ray diffraction (1.7 g, 85%). IR (KBr): n˜ =1645, 1618 cmꢀ1 (C=O);
elemental analysis (%) calcd for C22H26Cu2Li4N4O19 (Mr =804): C 32.81,
H 3.25, N 6.96; found: C 31.34, H 3.20, N 6.89.
NH), 10.80 ppm (s, 1H;
1 NH); IR (KBr): n˜ =3399 (N-H), 1732,
1704 cmꢀ1 (C=O); elemental analysis (%) calcd for C15H18N2O6 (Mr =
322): C 55.90, H 5.59, N 8.70; found: C 55.87, H 5.29, N 8.91.
Et2H2Me4ppba: Ethyl oxalyl chloride ester (14.0 mL, 120 mmol) was
poured into
a solution of 2,3,5,6-tetramethyl-para-phenylenediamine
(9.9 g, 60 mmol) in THF (250 mL) with vigorous stirring at 08C on an ice-
bath. The reaction mixture was heated to reflux for 1 h. After cooling,
the solid was collected by filtration, washed with diethyl ether, and dried
under vacuum (19.7 g, 90%). 1H NMR (C2D6SO): d=1.34 (t, 6H; 2ꢀ
AHCUTNGERTN(GNUN Ph4P)4ACHTUNTRGEG[NNUN Cu2ACHTUNGRTEN(NUGN Meppba)2]·8H2O (2c): An aqueous solution (10 mL) of
AgNO3 (1.4 g, 8.0 mmol) was added to an aqueous solution (20 mL) of
2b (1.6 g, 2.0 mmol) with stirring at room temperature. The dark-brown
solid that appeared was collected by filtration, suspended in water
(10 mL), and charged with a solution of Ph4PCl (3.0 g, 8.0 mmol) in ace-
tonitrile (5 mL). The reaction mixture was further stirred for 30 min with
gentle warming and then filtered to remove the precipitate of AgCl.
Slow evaporation of the filtered deep-brown solution gave dark-brown
crystals of 2c, which were not suitable for single-crystal X-ray diffraction
after several days in the open air at room temperature (3.9 g, 90%). IR
(KBr): n˜ =3425 (O-H), 1642, 1617 cmꢀ1 (C=O); elemental analysis (%)
calcd for C118H108Cu2N4O20P4 (Mr =2151): C 65.82, H 5.06, N 2.60; found:
C 65.45, H 4.99, N 2.77.
CH3), 2.02 (s, 12H; C6ACHTUNGTRENNUNG(CH3)4), 4.32 (q, 4H; 2ꢀCH2O), 10.43 ppm (s, 2H;
2 NH); IR (KBr): n˜ =3245 (N-H), 1728, 1676 cmꢀ1 (C=O); elemental
analysis (%) calcd for C18H24N2O6 (Mr =364): C 59.33, H 6.64, N 7.68;
found: C 58.98, H 6.67, N 7.74.
Preparation of the complexes
ACHTUNGTRENNUNG(nBu4N)4ACHTUNGTRENNUNG[Cu2ACHTUNGTRENNUNG(ppba)2]·2CH3OH (1a): A solution of nBu4NOH (20 mL,
20.0 mmol, 1.0m) in methanol was added in one portion to a suspension
of H2Et2ppba (1.6 g, 5.0 mmol) in methanol (50 mL). A solution of Cu-
ACHTUNGTRENNUNG(ClO4)2·6H2O (1.85 g, 5.0 mmol) in methanol (10 mL) was added drop-
wise to the reaction mixture with stirring at room temperature. The
deep-green solution was filtered to eliminate the small amount of solid
particles produced and the solvent was removed under vacuum. The
green solid was recuperated with acetone, collected by filtration, washed
thoroughly with THF to remove the precipitate of nBu4NClO4, and air
dried. Recrystallization from a solution in methanol gave large green
prisms of 1a suitable for single-crystal X-ray diffraction studies upon
layering of diethyl ether (3.3 g, 80%). IR (KBr): n˜ =1638, 1612 cmꢀ1 (C=
O); elemental analysis (%) calcd for C86H160Cu2N8O14 (Mr =1657): C
62.32, H 9.73, N 6.76; found: C 61.98, H 9.51, N 6.74.
ACHNUTERTG(NGUNN nBu4N)4AHCUTNRTGENG[NUN Cu2ACTHUNGTRENN(UNG Me4ppba)2]. 5H2O (3a): A solution of nBu4NOH (20 mL,
20.0 mmol) in methanol (1.0m) was added in one portion to a suspension
of H2Et2Me4ppba (1.8 g, 5.0 mmol) in methanol (50 mL). A solution of
CuACTHUNGRTNEUNG(ClO4)2·6H2O (1.85 g, 5.0 mmol) in methanol (10 mL) was added
dropwise with stirring at room temperature to the reaction mixture. The
deep-brown solution was filtered to eliminate a small amount of solid
particles, and the solvent was removed under vacuum. The dark-brown
solid was recuperated with acetone, collected by filtration, washed thor-
oughly with THF to remove the precipitate of nBu4NClO4, and air dried
(3.9 g, 85%). IR (KBr): n˜ =1642, 1615 cmꢀ1 (C=O); elemental analysis
(%) calcd for C94H178Cu2N8O17 (Mr =1820): C 61.54, H 9.99, N 6.24;
found: C 61.91, H 9.90, N 5.99
Li
4ACHTUNGTRENNUNG[Cu2ACHTUNGTRENNUNG(ppba)2]·10H2O (1b): An aqueous solution (10 mL) of Cu-
ACHTUNGTRENNUNG(NO3)2·3H2O (1.2 g, 5.0 mmol) was added dropwise to an aqueous solu-
tion (50 mL) of Et2H2ppba (1.5 g, 5.0 mmol) and LiOH·H2O (0.8 g,
20.0 mmol) with stirring at room temperature. The resulting deep-green
solution was filtered, and the solvent was reduced under vacuum until a
solid appeared. The light-green solid was collected by filtration, washed
with acetone and diethyl ether, and air dried (1.6 g, 75%). IR (KBr): n˜ =
1624, 1616 cmꢀ1 (C=O); elemental analysis (%) calcd for
C20H28Cu2Li4N4O22 (Mr =831): C 28.88, H 3.37, N 6.74; found: C 28.75, H
3.28, N 6.67.
Li
4ACHTUNGTRENGU[N Cu2HCATUNGTREN(NUGN Me4ppba)2]·9H2O (3b): An aqueous solution (10 mL) of Cu-
AHCTNUGTREN(GUNN NO3)2·3H2O (1.2 g, 5.0 mmol) was added dropwise to an aqueous solu-
tion (50 mL) of Et2H2Me4ppba (1.8 g, 5.0 mmol) and LiOH·H2O (0.8 g,
20.0 mmol) with stirring at room temperature. The resulting deep-brown
solution was then filtered, and the solvent was reduced under vacuum
until a solid appeared. The dark-brown solid was collected by filtration,
washed with acetone and diethyl ether, and air dried (2.0 g, 85%). IR
(KBr): n˜ =3473 (O-H), 1634, 1605 cmꢀ1 (C=O); elemental analysis (%)
calcd for C28H42Cu2Li4N4O21 (Mr =924): C 36.34, H 4.57, N 6.05; found: C
36.63, H 4.40, N 6.03
ACHTUNGTRENNUNG(Ph4P)4ACHTUNGTRENNUNG[Cu2ACHTUNGTRENNUNG(ppba)2]·8H2O (1c): An aqueous solution (10 mL) of AgNO3
(1.4 g, 8.0 mmol) was added to an aqueous solution (20 mL) of 1b (1.7 g,
2.0 mmol) with stirring at room temperature. The dark-green solid that
appeared was collected by filtration, suspended in water (10 mL), and
AHCTNUERTGGNU(NN Ph4P)4ACHTNURTEGG[NNUN Cu2CAHTNUGRTEN(NUGN Me4ppba)2]·15H2O (3c): An aqueous solution (10 mL) of
charged with
a solution of Ph4PCl (3.0 g, 8.0 mmol) in acetonitrile
AgNO3 (1.4 g, 8.0 mmol) was added to an aqueous solution (20 mL) of
3b (1.9 g, 2.0 mmol) with stirring at room temperature. The dark-brown
solid that appeared was collected by filtration, suspended in water
(10 mL), and charged with a solution of Ph4PCl (3.0 g, 8.0 mmol) in ace-
tonitrile (5 mL). The reaction mixture was further stirred for 30 min with
gentle warming and filtered to remove the precipitate of AgCl. Slow
evaporation of the filtered solution gave small dark-brown prisms of 3c,
which were suitable for single-crystal X-ray diffraction after several days
in the open air at room temperature (4.2 g, 90%). IR (KBr): n˜ =3413
(5 mL). The reaction mixture was further stirred for 30 min with gentle
warming and then filtered to remove the precipitate of AgCl. Slow evap-
oration of the filtered deep-green solution gave dark-green crystals of 1c,
which were not suitable for single-crystal X-ray diffraction after several
days in the open air at room temperature (4.2 g, 95%). IR (KBr): n˜ =
1644, 1603 cmꢀ1 (C=O); elemental analysis (%) calcd for
C
116H104Cu2N4O20P4 (Mr =2123): C 65.56, H 4.89, N 2.63; found: C 65.65,
H 4.82, N 2.47.
(nBu4N)4A[Cu2A(Meppba)2]·3H2O (2a): A solution of nBu4NOH (20 mL,
A
N
CHTUNGTRENNUNG
(O H), 1637, 1604 cmꢀ1 (C=O); elemental analysis (%) calcd for
ꢀ
20.0 mmol) in methanol (1.0m) was added in one portion to a suspension
of H2Et2Meppba (1.6 g, 5 mmol) in methanol (50 mL). A solution of Cu-
ACHTUNGTRENNUNG(ClO4)2·6H2O (1.85 g, 5.0 mmol) in methanol (10 mL) was then added
C124H134Cu2N4O27P4 (Mr =2363): C 63.02, H 5.71, N 2.37; found: C 63.99,
H 5.59, N 2.46.
Chemical oxidation and spectroscopic measurements: Variable-tempera-
ture (5–258C) UV/Vis–NIR spectra of solutions in acetonitrile were re-
corded on an Agilent Technologies-8453 spectrophotometer equipped
with a thermostated Chem Station. Varying amounts of a solution of bro-
mine (0.01m, 0–15 mL) were added stepwise to a solution of 3c in aceto-
nitrile (0.1 mm, 2.5 mL) at 5, 15, and 258C. In each case, the course of the
decomposition reaction of the monooxidized species was followed by
measuring the absorbance at lmax =875 nm as a function of time.
dropwise with stirring at room temperature to the reaction mixture. The
deep-brown solution was filtered to eliminate a small amount of solid
particles and the solvent was removed under vacuum. The dark-brown
solid was recuperated with acetone, collected by filtration, washed thor-
oughly with THF to remove the precipitate of nBu4NClO4, and air dried
(3.4 g, 80%). IR (KBr): n˜ =1638, 1615 cmꢀ1 (C=O); elemental analysis
(%) calcd for C88H162Cu2N8O15 (Mr =1700): C 61.65, H 9.75, N 6.69;
found: C 61.53, H 9.61, N 6.51.
Chem. Eur. J. 2013, 19, 12124 – 12137
ꢇ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
12135
Ferrando-Soria, Jesus
