5616 J. Am. Chem. Soc., Vol. 119, No. 24, 1997
Constable et al.
(w), 1261 (m), 849 (m), 787 (s), 771 (s). EI-MS (70 eV): m/z (relative
intensity) 398 (M+, 100), 397 (37), 383 (10), 371 (20), 370 (79), 369
(14), 365 (20), 338 (17), 205 (9), 199 (10), 185 (8), 155 (8). Anal.
Calcd for C24H22N4S: C, 72.33; H, 5.56; N, 14.06. Found: C, 72.01;
H, 5.53; N, 14.02.
156.74 (C), 156.50 (C), 155.62 (C), 155.56 (C), 153.88 (C), 153.29
(C), 149.14 (CH), 148.30 (C), 138.00 (CH), 136.95 (CH), 125.66 (CH),
123.99 (CH), 122.48 (CH), 122.28 (CH), 121.95 (CH), 121.92 (CH),
121.14 (CH), 121.05 (CH), 117.11 (C), 21.32 (CH3, 7-C). IR (KBr):
ν 3059 cm-1 (w), 2924 (m), 2853 (m), 2235 (w), 1595 (m), 1577 (m),
1552 (s), 1459 (m), 1391 (m), 1375 (m), 1268 (m), 1082 (m), 988 (m),
888 (m), 828 (m), 790 (s), 749 (m), 661 (m). EI-MS (70 eV): m/z
(relative intensity) 349 (M+, 100), 348 (18), 324 (3), 323 (2), 321 (4),
271 (3), 257 (2), 244 (1), 230 (2), 192 (2), 174 (6), 155 (4). Anal.
Calcd for C22H15N5: C, 75.63; H, 4.33; N, 20.04. Found: C, 75.33;
H, 4.52; N, 19.79.
4-Methyl-2,2′:6′,2′′:6′′,2′′′-quaterpyridine (1h). The preparation
of this compound was analogous to that of compound 1a from 0.67 g
(3.4 mmol) of 4, 0.65 g (3.4 mmol) of 12, 0.83 g (7.4 mmol) of
potassium tert-butoxide, 1.4 g (18 mmol) of NH4OAc, and 4.5 mL of
glacial acetic acid. After column chromatography (10:90 NHEt2-
hexanes/silica gel and then 60:40 CHCl3-hexanes/aluminum oxide)
and recrystallization (EtOH), 0.102 g (9.3%) of 1h as colorless plates
was obtained. Mp: 175.5-176.5 °C. 13C NMR (75 MHz, CDCl3): δ
156.26 (C), 156.02 (C), 155.50 (C), 155.46 (C), 155.38 (C), 155.33
(C), 149.11 (CH), 148.95 (CH), 147.99 (C), 137.79 (CH), 137.75 (CH),
136.85 (CH), 124.75 (CH), 123.74 (CH), 121.94 (CH), 121.19 (CH),
121.16 (CH), 121.06 (CH), 120.96 (CH), 21.35 (CH3, 7-C). IR
(KBr): ν 3051 cm-1 (m), 2999 (w), 2943 (w), 1606 (m), 1577 (s),
1566 (s), 1473 (m), 1446 (m), 1423 (s), 1400 (m), 1269 (m), 989 (m),
814 (m), 781 (s), 754 (m), 658 (m), 633 (m). EI-MS (70 eV): m/z
(relative intensity) 324 (M+, 100), 323 (28), 309 (3), 298 (3), 297 (3),
282 (2), 261 (2), 259 (1), 246 (6), 244 (2), 232 (5), 230 (2), 219 (3),
205 (3), 169 (5), 162 (5), 155 (6). Anal. Calcd for C21H16N4: C, 77.76;
H, 4.97; N, 17.27. Found: C, 77.00; H, 4.98; N, 17.08.
4-tert-Butyl-2,2′:6′,2′′:6′′,2′′′-quaterpyridine (1i). The preparation
of this compound was analogous to that of compound 1a from 0.56 g
(3.2 mmol) of 8, 1.05 g (4.2 mmol) of 13, 0.95 g (8.5 mmol) of
potassium tert-butoxide, 1.6 g (21 mmol) of NH4OAc, and 5.2 mL of
glacial acetic acid. After column chromatography (PhMe and then 10:
90 NHEt2-hexanes, both on aluminum oxide) and recrystallization
(hexanes), 0.26 g (22%) of 1i as pale yellow microcrystals was obtained.
Mp: 122-123 °C. 13C NMR (75 MHz, CDCl3): δ 160.83 (C), 156.20
(C), 156.06 (C), 155.72 (C), 155.36 (C), 155.27 (C), 155.21 (C), 149.05
(CH), 137.80 (CH), 137.71 (CH), 136.81 (CH), 123.70 (CH), 121.15
(CH), 120.93 (CH), 120.87 (CH), 120.83 (CH), 118.01 (CH), 34.94
(C, 7-C), 30.60 (CH3, 8-C). IR (KBr): ν 3059 cm-1 (w), 2966 (m),
2868 (w), 1592 (w), 1566 (s), 1473 (m), 1425 (m), 1400 (m), 1271
(m), 1109 (w), 814 (m), 779 (s), 752 (w), 658 (w). EI-MS (70 eV):
m/z (relative intensity) 366 (M+, 88), 365 (58), 351 (100), 349 (5),
345 (5), 344 (4), 335 (6), 324 (12), 310 (39), 309 (14), 289 (4), 282
(3), 232 (5), 205 (3), 183 (6), 176 (10), 175 (14). Anal. Calcd for
C24H22N4: C, 78.66; H, 6.05; N, 15.29. Found: C, 78.53; H, 6.03; N,
15.13.
General Preparation of the Dicopper(I) Helicates of Ligands 1a-
i. Mixtures of 1a-i and tetrakis(acetonitrile)copper(I) hexafluorophos-
phate were heated in degassed methanol under reflux under an
atmosphere of N2 or Ar (1d, 1h and 1i) for 30-60 min. After this, the
qtpy ligands had dissolved and deep red solutions had been obtained.
Methanolic ammonium hexafluorophosphate was added to the hot
solutions, and after 1-2 h at room temperature, the supernatant solvent
was removed with a pipet. The precipitated complexes were washed
twice with cold methanol and dried under vacuum. The crude
complexes were recrystallized after filtration of a solution through a
small amount of Celite.
4-tert-Butyl-4′-(ethylthio)-2,2′:6′,2′′:6′′,2′′′-quaterpyridine (1d).
The preparation of this compound was analogous to that of compound
1a from 0.71 g (2.2 mmol) of 11, 0.50 g (2.8 mmol) of 8, 0.63 g (5.6
mmol) of potassium tert-butoxide, 2.2 g (29 mmol) of NH4OAc, and
14 mL of glacial acetic acid. Column chromatography (20:80 NHEt2-
hexanes/silica gel) afforded 0.13 g of 11 and 0.31 g (33%) of 1d after
recrystallization (hexanes) of the latter compound. Mp: 137.5-138.5
°C. 13C NMR (75 MHz, CDCl3): δ 160.87 (C), 156.17 (C), 155.80
(C), 155.50 (C), 155.24 (C), 155.09 (C), 154.81 (C), 151.08 (C), 149.09
(CH), 148.96 (CH), 137.81 (CH), 136.87 (CH), 123.74 (CH), 121.14
(CH), 121.06 (CH), 118.28 (CH), 117.96 (CH), 117.68 (CH), 34.96
(C, 7-C), 30.62 (CH3, 8-C), 25.13 (CH2, 8′-C), 13.78 (CH3, 9′-C). IR
(KBr): ν 3062 cm-1 (w), 2964 (m), 2927 (m), 2864 (m), 1564 (s),
1542 (s), 1473 (m), 1460 (m), 1423 (m), 1377 (s), 1327 (w), 989 (w),
870 (w), 843 (w), 825 (m), 783 (m), 744 (m), 660 (m). EI-MS (70
eV): m/z (relative intensity) 426 (M+, 100), 425 (37), 412 (14), 411
(49), 399 (16), 398 (59), 393 (14), 384 (11), 370 (22), 250 (5), 213
(10), 205 (12), 198 (9), 192 (6), 184 (4). Anal. Calcd for C26H26N4:
C, 73.21; H, 6.14; N, 13.13. Found: C, 73.37; H, 6.19; N, 13.07.
6-Methyl-4′-(ethylthio)-2,2′:6′,2′′:6′′,2′′′-quaterpyridine (1e). The
preparation of this compound was analogous to that of compound 1a
from 0.54 g (2.0 mmol) of 10, 0.40 g (2.0 mmol) of 4, 0.45 g (4.0
mmol) of potassium tert-butoxide, 1.3 g (17 mmol) of NH4OAc, and
8 mL of glacial acetic acid. After column chromatography (20:80
NHEt2-hexanes/silica gel and then 60:40 CHCl3-PhMe/aluminium
oxide) and recrystallization (CHCl3-pentane), 0.37 g (46%) of 1e was
obtained as colorless plates. Mp: 127.5-128 °C. 13C NMR (75 MHz,
CDCl3): δ 157.67 (C), 156.12 (C), 155.25 (C), 155.21 (C), 155.11
(C), 155.08 (C), 154.81 (C), 150.87 (C), 149.14 (CH), 137.76 (CH),
136.99 (CH), 136.89 (CH), 123.77 (CH), 123.42 (CH), 121.37 (CH),
121.16 (CH), 121.08 (CH), 118.44 (CH), 117.75 (CH), 25.22 (CH2,
8′-C), 24.73 (CH3, 7-C), 13.86 (CH3, 9′-C). IR (KBr): ν 3049 cm-1
(w), 2974 (m), 2927 (m), 2871 (w), 1562 (s), 1543 (s), 1458 (s), 1429
(m), 1396 (s), 1263 (m), 1126 (m), 1082 (m), 984 (m), 874 (m), 810
(m), 779 (s). EI-MS (70 eV): m/z (relative intensity) 385 (M+, 80),
383 (10), 369 (16), 356 (100), 355 (10), 351 (31), 324 (31), 323 (8),
312 (15), 205 (12), 192 (10), 178 (11), 155 (8), 142 (6). Anal. Calcd
for C23H20N4S: C, 71.85; H, 5.24; N, 14.57. Found: C, 71.41; H,
5.22; N, 14.54.
4-Methyl-4′-(ethylsulfonyl)-2,2′:6′,2′′:6′′,2′′′-quaterpyridine (1f).
A mixture of 0.41 g (1.1 mmol) of 1b and 0.43 g (2.1 mmol, 85%
pure) of 3-chloroperbenzoic acid in 5 mL of CH2Cl2 was stirred
overnight at ambient temperature. At the end of that time, the solvent
was removed under reduced pressure, and the residual material was
dissolved in CHCl3. The organic solution was washed with a saturated
NaHCO3 solution (5 × 8 mL) and once with brine and dried (Na2-
SO4). Recrystallization (4:1 EtOH-EtOAc) afforded 0.34 g (74%) of
1f as fine yellow needles. Mp: 203-204.5 °C. 13C NMR (75 MHz,
CDCl3): δ 157.72 (C), 157.44 (C), 155.86 (C), 155.68 (C), 154.27
(C), 153.78 (C), 149.30 (CH), 149.17 (CH), 148.97 (C), 148.30 (C),
138.07 (CH), 137.12 (CH), 125.68 (CH), 124.06 (CH), 122.23 (CH),
122.01 (CH), 121.40 (CH), 118.73 (CH), 118.30 (CH), 50.09 (CH2,
8′-C), 29.69 (CH3, 7/9′-C), 7.19 (CH3, 7/9′-C). IR (KBr): ν 3095 cm-1
(w), 2931 (w), 2850 (w), 1604 (w), 1560 (s), 1375 (m), 1317 (s), 1269
(m), 1143 (s), 827 (m), 785 (m), 723 (m), 660 (w), 534 (m). EI-MS
(70 eV): m/z (relative intensity) 416 (M+, 30), 352 (11), 351 (15),
324 (100), 323 (10), 205 (14), 182 (3), 162 (8), 155 (9), 142 (10).
Anal. Calcd for C23H20N4O2S: C, 66.33; H, 4.84; N, 13.45. Found:
C, 66.22; H, 5.06; N, 13.20.
[Cu2(1a)2][PF6]2. Combination of 30 mg (0.084 mmol) of 1a, 31
mg (0.084 mmol) of [(CH3CN)4Cu][PF6] in 3 mL of MeOH, and 250
mg of [NH4][PF6] resulted in 21 mg (44% yield) of the product after
recrystallization (2×) from MeCN-Et2O. IR (KBr): ν 3093 cm-1 (w),
1601 (s), 1462 (m), 1437 (w), 1419 (w), 1402 (w), 1327 (w), 1252
(w), 1167 (w), 1117 (w), 1230 (m), 840 (s), 783 (m), 557 (s). FAB-
MS (NBA): m/z (relative intensity) 984 (4.1, Cu2(1a)2), 440 (4.9, Cu-
(1a)). Anal. Calcd for C42H32Cu2F12N8P2S2: C, 44.65; H, 2.85; N,
9.92. Found: C, 44.0; H, 3.6; N, 9.7.
[Cu2(1b)2][PF6]2. Combination of 50 mg (0.13 mmol) of 1b, 47
mg (0.13 mmol) of [(CH3CN)4Cu][PF6] in 7 mL of MeOH, and 250
mg [NH4][PF6] resulted in 63 mg (82% yield) of the product. The
sample for the combustion analysis was twice recrystallized from
4-Methyl-4′-cyano-2,2′:6′,2′′:6′′,2′′′-quaterpyridine (1g). A mix-
ture of 0.22 g (0.54 mmol) of 1f and 0.38 g (6 mmol) of potassium
cyanide in 8 mL of dry DMF was heated under reflux for 96 h under
nitrogen gas. The mixture was poured into a brine solution (30 mL)
and extracted with CHCl3 (3 × 5 mL). The combined organic extracts
were washed with water (3 × 5 mL) and once with brine and dried
(Na2SO4). After solvent removal under reduced pressure, recrystalli-
zation (EtOH-EtOAc) gave 0.16 g (83%) of 1g as beige plates. Mp:
189.7-190.4 °C. 13C NMR (75 MHz, CDCl3): δ 200.45 (C, 7′-C),