J.-M. Lehn et al.
FULL PAPER
lyses, Université Louis Pasteur, all samples being gently dried by
storage in an unevacuated desiccator containing concentrated
H2SO4 as desiccant for at least 3 d.
1
227 °C. H NMR ([D6]dmso): δ = 11.85 (br., 2 H), 8.43 (m, 2 H),
8.25 (m, 1 H), 8.09 (m, 2 H), 7.58 (br. m, 3 H), 2.68 (m, 2 H), 2.31
(m, 2 H), 1.63 (m, 4 H), 1.32 (m, 16 H), 0.86 (m, 6 H) ppm. 13C
NMR (CDCl3): δ = 174.8, 169.3, 163.9, 161.3, 160.9, 143.9, 143.6,
141.0, 140.5, 136.5, 131.2 128.7, 127.8, 108.2, 107.3, 34.3, 31.8,
31.2, 28.8, 28.7, 28.5, 28.4, 24.8, 24.2, 24.0, 22.1, 13.92,13.88 ppm.
ESMS: m/z (%) = 492.30 (100) [M + H]+.
Synthesis
(a) 2-Phenylpyrimidine-4,6-dicarbaldehyde: A stirred solution of
4,6-dimethyl-2-phenylpyrimidine (5.08 g; 27.6 mmol), iodine
(14.02 g; 53.2 mmol) and trifluoroacetic acid (8.0 mL; 103.8 mmol)
in deoxygenated dmso (200 mL) was heated, under argon, at 150 °C
for 135 min. After cooling to ambient temperature, further manipu-
lations were conducted under the normal atmosphere. A solution
of Na2S2O3·5H2O (31.6 g; 127.3 mmol) in water (100 mL) was
added, causing discharge of the I2 colour, after which the solution
was neutralised by the addition of saturated NaHCO3 solution.
The product was extracted into CH2Cl2 (6ϫ100 mL) and the com-
bined extracts dried with MgSO4 before being taken to dryness in
vacuo. The dmso remaining in the orange residue was removed by
high-vacuum distillation, and the product was then crystallised
from diethyl ether as pale yellow needles. Yield: 4.06 g (19.2 mmol,
80%). M.p. 123.5 °C. 1H NMR (CDCl3): δ = 10.18 (s, 2 H, 7,8-H),
(iv) R = C6H5, RЈ = H (4H2): Solutions of 2-phenylpyrimidine-
4,6-dicarbaldehyde (50 mg) in CH3CN (3 mL) and benzohydrazide
(64 mg) in CH3CN (2 mL) were mixed to give a pale yellow solu-
tion. Within 2 min, deposition of pale yellow, globular material
commenced, and, on continued standing, this material transformed
into clusters of pale yellow needles. After 12 h, the solid was col-
lected, washed with CH3CN and dried in air. Yield: 98 mg (93%).
Use of methanol as a solvent gave essentially the same result,
though initiation of the precipitation was slower (ca. 30 min). The
compound was recrystallised from pyridine by addition of acetoni-
trile. C26H20N6O2·1/2H2O (457.49): calcd. C 68.26, H 4.63, N 18.37;
found C 68.4, H 4.74, N 18.1%. M.p. 286–287 °C. 1H NMR ([D6]-
3
dmso): δ = 12.40 (s, 2 H), 8.56 (s, 2 H), 8.45 (t, J = 3.6 Hz, 2 H),
3
8.60 (d, J = 7.9 Hz, 2 H, 10,14-H), 8.12 (s, 1 H, 5-H), 7.58 (m, 3
3
8.35 (s, 1 H), 7.98 (d, J = 7.2 Hz, 4 H) 7.67–7.62 (m, 3 H), 7.62–
H, 11,12,13-H) ppm. 13C NMR (CDCl3): δ = 192.13 (C-7,8), 166.76
(C-2), 160.25 (C-4,6), 135.50 (C-9), 128.60, 128.93 (C-10,14, C-
11,13), 132.17 (C-12), 109.97 (C-5) ppm.
7.53 (m, 6 H) ppm. 13C NMR ([D6]dmso): δ = 164.0, 163.6, 161.3,
145.7, 136.5, 132.8, 132.3, 131.2, 128.8, 128.6, 127.9, 108.9 ppm.
ESMS: m/z (%) = 449.10 (100) [M + H]+.
(b) Bis(acylhydrazone)s of 2-Phenylpyrimidine-4,6-dicarbaldehyde,
RCONRЈN=CHC10H6N2CH=NNRЈCOR
(v) R = 4-CH3C6H4, RЈ = H (5H2): The procedure used for ligand
3H2 was followed for the reaction of 2-phenylpyrimidine-4,6-dicar-
baldehyde (223 mg) and toluohydrazide (331 mg), the acylhydra-
zone again precipitating as an almost white solid which was recrys-
tallised from pyridine by addition of acetonitrile. Yield: 364 mg
(73%). C28H24N6O2 (476.53): calcd. C 70.57, H 5.08, N 17.64;
found C 70.5, H 4.69, N 17.6%. M.p. 287–288 °C. 1H NMR ([D6]-
dmso): δ = 14.59 (w), 12.39 (w), 12.34, 8.56, 8.46, 8.34, 8.22 (w),
8.21 (w), 7.90, 7.89, 7.81 (w), 7.79 (w), 7.59, 7.40, 7.38, 7.33 (w),
7.31 (w), 2.44 (w), 2.41 ppm. 13C NMR ([D6]dmso): δ = 164.0,
163.4, 161.3, 158.2, 145.4, 142.5, 136.5, 136.1, 131.6, 131.2, 129.9,
129.8, 129.4, 129.2, 128.8, 128.2, 127.9, 127.7, 114.9, 108.8, 104.5,
104.4, 21.13, 21.09 ppm. ESMS: m/z (%) = 477.2 (100) [M + H]+.
(i) R = CH3, RЈ = H (1H2): Solutions of 2-phenylpyrimidine-4,6-
dicarbaldehyde (250 mg) in CH3CN (10 mL) and acetohydrazide
(190 mg) in CH3CN (10 mL) were mixed to give a pale yellow solu-
tion. Within 30 s, the solution became turbid, and after 5 min, for-
mation of a granular but not obviously crystalline pale yellow pre-
cipitate was extensive. After 12 h, the well-settled precipitate was
separated from the colourless supernatant, washed with CH3CN
and diethyl ether, and dried in vacuo. Yield: 280 mg (80%).
C16H16N6O2·1/4H2O (327.85): calcd. C 58.51, H 4.99, N 25.63;
found C 58.7, H 4.85, N 25.2%. M.p. Ͼ 310 °C (decomp.). 1H
NMR ([D6]dmso): δ = 11.93, 11.91, 11.83 (NH), 8.41 (m, br), 8.24,
8.20, 8.17, 8.10, 8.09, 8.07, 8.05, 7.57, 2.28, 2.27, 2.04 ppm. 13C
NMR ([D6]dmso): δ = 172.5, 172.4, 166.3, 166.2, 163.8, 161.2,
160.8, 143.9, 143.4, 141.1, 140.6, 136.4, 131.1, 128.7, 127.8, 108.1,
107.8, 54.8, 21.7, 20.2, 19.9 ppm. ESMS: m/z (%) = 325.24 (100)
[M + H]+.
(vi) R = CH3OCH2, RЈ = H (6H2): CH3OCH2CONHNH2 (21 mg)
in CH3CN (1 mL) and 2-phenylpyrimidine-4,6-dicarbaldehyde
(22 mg) in CH3CN (1 mL) were mixed to give a slightly cloudy,
pale yellow solution, which was filtered (the cloudiness appearing
to be due to traces of acid impurity in the hydrazide) before being
mixed with a solution of [Ga(dmso)6](CF3SO3)3 (5 mg; ca. 0.1 mo-
lar equivalent) in CH3CN (1 mL). The colour of the mixture
changed to a deeper yellow, and within 5 min, deposition of the
product commenced. (In the absence of GaIII, no precipitate forms
within at least 2 h.) After 1 h, the solid was collected and washed
with CH3CN and diethyl ether. Yield: 30 mg (75%). The com-
pound was recrystallised from hot thf by addition of an equal vol-
ume of diethyl ether after cooling. C18H20N6O4·1/2H2O (393.40):
calcd. C 54.96, H 5.38, N 21.36; found C 54.9, H 5.1, N 21.8%.
(ii) R = C2H5, RЈ CH3 (2): 2-Phenylpyrimidine-4,6-dicarbaldehyde
(421 mg) and 1-methyl-1-propionylhydrazine (405 mg) were dis-
solved in ethanol (35 mL), and the solution was stirred at room
temperature for 24 h as a yellow precipitate formed. The precipitate
was collected, washed with ethanol and dried under vacuum. Yield:
443 mg (59%). The compound was recrystallised from CHCl3 by
addition of CH3CN. M.p. 231–232 °C. 1H NMR (CDCl3): δ =
8.49–8.46 (m, 2 H), 8.24 (s, 1 H), 7.77 (s, 2 H), 7.51–7.50 (m, 3 H),
2.93 (q, J = 7.6 Hz, 4 H), 1.25 (t, J = 7.6 Hz, 6 H) ppm. 13C NMR
(CDCl3): δ = 176.2, 165.3, 161.7, 137.2, 137.1, 131.3, 128.9, 128.5,
108.3, 28.5, 27.2, 9.6 ppm. ESMS: m/z (%) = 381.30 (100) {[M +
H]+ = [C20H24N6O2 + H]+}.
1
M.p. 238–239 °C. H NMR ([D6]dmso): δ = 11.93 (NH) (two very
weak peaks at δ = 13.86 and 12.00 ppm may also be NH reso-
3
nances), 8.43 (s, br.), 8.39 (m, br.), 8.20, 8.01 (t, J = 15 Hz), 7.55
(s, br.), 4.49, 4.08, 3.39, 3.35 ppm. 13C NMR ([D6]dmso): δ = 171.6,
166.9, 164.4, 161.7, 161.1, 146.3, 146.0, 142.3, 141.6, 136.8, 131.7,
129.2, 128.3, 109.4, 108.9, 108.7, 71.5, 69.4, 59.3, 59.0 ppm. ESMS:
m/z (%) = 385.29 (100) [M + H]+.
(iii) R = C7H15, RЈ = H (3H2): Essentially the same procedure as
described for the synthesis of 1H2 was followed, except that ethanol
(20 mL) was used as solvent in the reaction of 2-phenylpyrimidine-
4,6-dicarbaldehyde (273 mg) and heptanohydrazide (469 mg), the
acylhydrazone precipitating as an almost white solid. Yield: 478 mg
(75%). The compound was recrystallised from boiling acetonitrile
(or methanol) by cooling on ice. C28H40N6O2 (492.66): calcd. C
68.26, H 8.18, N 17.06; found C 68.6, H 8.10, N 17.1%. M.p. 225–
(vii) R = CH3OCH2CH2OCH2, RЈ = H (7H2): The relatively high
solubility of the product in most organic solvents made its direct
precipitation from the volume of solvent required to dissolve the
reactants rather inefficient. Hence, 2-phenylpyrimidine-4,6-dicarb-
2960
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Eur. J. Inorg. Chem. 2007, 2944–2965