J. Reedijk et al.
FULL PAPER
Synthesis of 2-(1-Methyl-1H-pyrazol-5-yl)naphthalen-1-ol (4b) and Preparation of the Coordination Compounds
2-(1-Methyl-1H-pyrazol-3-yl)naphthalen-1-ol (5b): 3 g (0.0124 mol)
Synthesis of [Cu
2
(4a)
2
Br
2
]
n
(7): A solution of ligand 4a (100 mg,
of 3b and 6 mL (0.1120 mol) of methylhydrazine were mixed in
a 50 mL round-bottomed flask containing 10 mL of ethanol. The
reaction mixture was heated at 60 °C, and stirred for 30 min at this
temperature. After cooling to room temperature, 30 mL of distilled
water were added, resulting in a light brown emulsion. This solu-
tion was extracted with dichloromethane (3ϫ50 mL). The pooled
organic phase was dried with magnesium sulfate, filtered, and the
solvent was evaporated under reduced pressure. The resulting
brown viscous crude compound was purified by column
0
.628 mmol) in methanol (10 mL) was added to a solution of cop-
per(II) bromide (140 mg, 0.628 mmol) in methanol (10 mL). The
resulting dark-green solution was filtered and the filtrate was left
unperturbed for the slow evaporation of the solvent. After one day,
colourless crystals of 7 were collected (yield 146 mg, 77%).
C
18
H18Br
2
Cu
C 35.20, H 2.93, N 13.72. IR (neat): ν˜ = 3119, 3051, 1599, 1465,
420, 1390, 1284, 1225, 1009, 940, 808, 786, 755, 700, 645, 542, 414
2 6
N (605.28): calcd. C 35.72, H 3.00, N 13.88; found
1
–
1
cm . Unit cell parameters: a = 7.668(2) Å, b = 8.492(2) Å, c =
.174(2) Å, α = 96.90(3)°, β = 114.06(3)°, γ = 107.49(3)° (see Table
2
chromatography (SiO , ethyl acetate/hexane, 1:1), yielding 1.6 g of
9
S1).
4b (58%) and 0.78 g of 5b (28%).
Isomer 4b:[48]
found C 74.92, H 5.17, N 12.53. M.p. 85 °C. ES(+)-MS: m/z =
C
H
12
N
2
O (224.26): calcd. C 74.98, H 5.39, N 12.49;
The same coordination compound (as evidenced by single-crystal
X-ray analysis) was obtained from an acetonitrile solution of the
reactants (using the same concentration), but after one week (in-
stead of one day in methanol).
14
+
2
1
24.91 [M + H ]. FT-IR (neat solid): ν˜ = 2938, 1576, 1495, 1386,
–1 1
354, 1089, 805, 755, 745, 698, 659, 572, 486, 422 cm . H NMR
3
(300 MHz, CDCl
3
, 20 °C): δ = 3.98 (s, 3 H, CH
3
), 6.68 (d, JH,H
=
Complex 7 has also been isolated during the catalysis reactions,
and characterized by X-ray diffraction analysis.
3
2
7
.3 Hz, 1 H, 4-H pz), 7.38 (d, JH,H = 8.6 Hz, 1 H, 4-H naphthol),
.43 (d, JH,H = 2.3 Hz, 1 H, 3-H pz), 7.45 (dd, JH,H = 4.8 Hz, 1
3
3
3
H, 6-H naphthol), 7.49 (dd, JH,H = 3.9 Hz, 1 H, 7-H naphthol),
Complex 7 is insoluble in common solvents such as methanol, ace-
tonitrile, THF, chloroform and dichloromethane. Consequently,
NMR studies of the solution structure of the diamagnetic complex
are not possible.
3
7
4
.65 (d, 3
.8 Hz, 1 H, 5-H naphthol), 8.42 (d,
H,H
JH,H = 8.6 Hz, 1 H, 3-H naphthol), 7.77 (d, J =
3
J
H,H = 3.9 Hz, 1 H, 8-H
13
naphthol), 11.60 (br. s, 1 H, O–H) ppm. C NMR (75 MHz,
CDCl , 20 °C): δ = 38.3, 101.9, 109.7, 118.5, 122.7, 123.6, 125.0,
25.3, 126.2, 127.2, 130.7, 133.8, 151.2, 151.4 ppm.
3
Complex 7 can also be prepared directly from CuBr and the ligand
1
4a, using the following reaction conditions: a solution of ligand 4a
(
25 mg, 0.157 mmol) in acetonitrile (5 mL) was added to a solution
Single-crystals of 4b were obtained, which were analysed by X-ray
diffraction. An ORTEP view of ligand 4b is depicted in Figure S8.
The molecular structure is uneventful and as expected.
of copper(I) bromide (23 mg, 0.157 mmol) in acetonitrile (5 mL).
The resulting light-green solution was filtered and the filtrate was
left unperturbed for the slow evaporation of the solvent. After two
hours, colourless crystals of 7 started to grow. The crystals were
Isomer 5b:[48]
found C 74.57, H 5.14, N 12.49. M.p. 142 °C. ES(+)-MS: m/z =
14 12 2
C H N O (224.26): calcd. C 74.98, H 5.39, N 12.49;
collected after one day (yield 31 mg, 33%). C18
605.28): calcd. C 35.72, H 3.00, N 13.88; found C 35.31, H 2.82,
N 13.75. IR (neat): ν˜ = 3119, 3054, 1560, 1464, 1418, 1392, 1284,
2 2 6
H18Br Cu N
(
+
2
1
(
1
7
24.98 [M + H ]. FT-IR (neat solid): ν˜ = 2943, 1571, 1389, 1292,
–1 1
199, 1074, 809, 788, 739, 667, 570, 484, 436, 423 cm . H NMR
300 MHz, CDCl , 20 °C): δ = 3.80 (s, 3 H, CH ), 6.43 (d, JH,H =
3 3
.8 Hz, 1 H, 4-H pz), 7.25 (d, JH,H = 8.2 Hz, 1 H, 4-H naphthol),
.49 (d, JH,H = 8.2 Hz, 1 H, 3-H naphthol), 7.53–7.59 (m, 2 H, 6-
–
1
1
225, 1010, 940, 808, 786, 755, 700, 645, 543, 414 cm . The struc-
3
ture, corresponding to complex 7, was confirmed by X-ray diffrac-
tion analysis. Unit cell parameters: a = 7.661(2) Å, b = 8.502(2) Å,
c = 9.160(2) Å, α = 96.90(3)°, β = 114.12(3)°, γ = 107.39(3)°.
3
3
3
H naphthol + 7-H naphthol), 7.61 (d, JH,H = 1.8 Hz, 1 H, 3-H
3
3
pz), 7.84 (d, JH,H = 9.3 Hz, 1 H, 5-H naphthol), 8.33 (d, JH,H
=
3
Synthesis of [Cu(4aH)Br ] (8): Red crystals of 8 were obtained from
3
9
(
1
.5 Hz, 1 H, 8-H naphthol), 11.72 (br. s, 1 H, O–H) ppm. 1 C NMR
75 MHz, CDCl , 20 °C): δ = 36.8, 106.8, 110.3, 119.8, 122.8, 125.1,
25.6, 127.1, 127.2, 127.4, 134.8, 138.7, 139.6, 150.4 ppm.
the solution above. Since these few single-crystals were mixed with
crystals of 7, they were only characterised by X-ray diffraction (see
Discussion). Unit cell parameters: a = 7.611(2) Å, b = 7.908(2) Å,
c = 11.787(2) Å, α = 104.99(3)°, β = 100.48(3)°, γ = 94.75(3)° (see
Table S1).
3
Synthesis of 2-(1H-Pyrazol-5-yl)naphthalen-1-ol (6b):[48] 2.76 g
0.0114 mol) of 3b and 6 mL (0.1235 mol) of hydrazine monohy-
drate were mixed in a 50 mL round-bottomed flask containing
mL of ethanol. The reaction mixture was heated at 60 °C and
(
However, complex 8 could also be synthesized from CuBr
a·HBr according to the following procedure: 18 µL (0.157 mmol)
of HBraq 48% were added to a solution of ligand 4a (25 mg,
2
and
4
9
stirred for 30 min at this temperature. After cooling to room tem-
perature, 30 mL of distilled water were added, producing a light
brown crystalline product. This solid was filtered off, and washed
with hexane (2ϫ200 mL). After drying at 100 °C for 4 h, the pure
0
1
.157 mmol) in 5 mL of acetonitrile. The solution was stirred for
0 min, and 35 mg (0.157 mmol) of CuBr were subsequently
2
added. The resulting dark-green solution was filtered and the fil-
trate was left unperturbed for the slow evaporation of the solvent.
After one day, red needle-shaped crystals were collected (yield
1
9
1
1
ture, corresponding to complex 8, was confirmed by X-ray diffrac-
tion analysis. Unit cell parameters: a = 7.598(2) Å, b = 7.892(2) Å,
c = 11.785(2) Å, α = 105.12(3)°, β = 100.39(3)°, γ = 94.81(3)°.
ligand 6b was obtained. Yield 1.8 g (75%). C13
10 2
H N O (210.23):
calcd. C 74.27, H 4.79, N 13.33; found C 74.16, H 4.99, N 13.18.
9 3 3
7 mg, 23%). C H10Br CuN (463.45): calcd. C 23.32, H 2.17, N
.07; found C 23.10, H 2.63, N 9.12. IR (neat): ν˜ = 2934, 2879,
+
+
ES(+)-MS: m/z = 210.92 [M ], 232.92 [M + Na ]. FT-IR (neat
solid): ν˜ = 3303, 3054, 1636, 1579, 1505, 1389, 1283, 1077, 976,
633, 1612, 1558, 1490, 1447, 1422, 1392, 1285, 1226, 1186, 1168,
–1
1
8
78, 759, 720, 656, 571, 484, 420 cm . H NMR (300 MHz,
–
1
062, 1009, 914, 815, 764, 684, 640, 524, 469, 378 cm . The struc-
3
CDCl
3
, 20 °C): δ = 6.80 (d, JH,H = 2.6 Hz, 1 H, 4-H pz), 7.41 (d,
H,H = 8.6 Hz, 1 H, 4-H naphthol), 7.46–7.53 (m, 2 H, 3-H naph-
thol + 6-H naphthol), 7.67–7.70 (m, 2 H, 7-H naphthol + 3-H pz),
JH,H = 9.4 Hz, 1 H, 5-H naphthol), 8.43 (d, J =
H,H
.7 Hz, 1 H, 8-H naphthol), 10.2–10.8 (v br. s, 2 H, O–H + N–H)
3
J
7
9
.78 (d, 3
3
Complex 8 could be obtained as well by addition of HBr to a solu-
tion of complex 7. As for the preparation of complex 7 (from CuBr,
ppm.
4204
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Eur. J. Inorg. Chem. 2007, 4197–4206