Inorganic Chemistry
ARTICLE
(300 MHz, CDCl3): δ 8.76 (d, 1H, J = 4.2 Hz), 8.69 (s, 1H), 8.26 (d, 1H,
J = 7.9 Hz), 7.88 (td, 1H, J = 7.6, 1.7 Hz), 7.70 (d, 2H, J = 8.5 Hz),
7.51 (m, 1H), 7.46 (m, 5H) ppm. 13C NMR (151 MHz, CDCl3):
δ 160.2, 154.6, 149.8, 141.7, 136.7, 134.5, 127.8, 127.2, 126.3, 126.2,
125.1, 121.9, 121.7, 120.2 ppm. MS (EI +): m/z 264 [M+, 100%].
HRMS (EI +) calculated for [C16H12N2S]+: 264.70212. Found:
264.07204. FT-IR (KBr): 3435 (br, m), 3065 (w), 2920 (w), 1622 (br,
m), 1472 (m), 1423 (m), 1350 (w), 1261 (m), 1202 (m), 1101 (br, m),
1034 (m), 833 (w), 783 (s), 538 (m) cmꢀ1. Elemental analysis calculated
(found) % for C16H12N2S: C, 72.71 (71.94); H, 4.58 (4.72); N, 10.60
(9.89).
C50H36N5S2Fe 0.5CH2Cl2: C, 68.67 (68.93); H, 4.22 (4.68); N, 9.51
3
(9.34). UVꢀvis (CH2Cl2): λmax (ε(Mꢀ1 cmꢀ1)) 621 nm (1510).
[Fe(4)2(NCS)2] (8). A solution of KSCN (93 mg, 0.96 mmol) in
MeOH (50 mL) was sparged with N2 gas for 0.5 h, combined with
Fe(II)SO4 7H2O (132 mg, 0.47 mmol). The mixture was stirred
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for an additional 0.5 h and then combined with 4 (250 mg, 0.95 mmol).
The solution was stirred under an atmosphere of nitrogen for 3 days,
concentrated to 20 mL, and cooled in an ice bath. The resulting green
precipitate was collected by vacuum filtration and washed with water
and pentane and then dried. Yield: 312 mg (94%). MS (FAB +): m/z
700 [M+, 10%], 642 [(M ꢀ SCN)+, 60%], 378 [(M ꢀ C17H12N3S2)+,
100%]. FT-IR (KBr): 3092 (w), 2064 (s), 2037 (s), 1589 (br, m),
1487 (w), 1433 (w), 1354 (w), 1300 (w), 1258 (w), 1200 (m), 1150
(w), 1105 (w), 1015 (w), 962 (w), 904 (w), 853 (w), 785 (m), 731
(w), 689 (w), 629 (w), 554 (w) cmꢀ1. Elemental analysis cal-
culated (found)% for C34H24N6S5Fe: C, 58.29 (58.31); H, 3.45
(3.12); N, 12.00 (11.92). UVꢀvis (CH2Cl2): λmax (ε (Mꢀ1 cmꢀ1))
630 nm (1690).
2,5-Bis(thiophen-2-yl)aniline (5). 2,5-Dibromoaniline (0.453 g
2.16 mmol) was added to a round-bottom flask and then combined with
anhydrous 1,2-dimethoxyethane (34 mL) and a 1.0 M aqueous solution of
K2CO3 (17 mL). The mixture was purged by N2 sparging for 0.5 h,
followed by the addition of 2-thienylboronic acid (0.829 g, 6.48 mmol)
and Pd(PPh3)4 (0.250 g, 0.22 mmol). The reaction mixture was heated at
95 °C for 72 h. The reaction contentswere combined withH2O (200 mL)
containing 20 g of NaCl and extracted into CH2Cl2 (200 mL). The
organic extracts were combined, dried over MgSO4, concentrated
(not to dryness) by rotary evaporation, dissolved in hexanes, and then
filtered through Celite. The filtrate was concentrated to dryness to
obtain an orange oil. Yield: 305 mg (55%). 1H NMR (300 MHz,
CDCl3): δ 7.42 (m, 3H), 7.34 (dd, 1H, J = 5, 0.5 Hz), 7.30 (dd, 1H,
J = 3.5, 0.8 Hz), 7.20 (dd, 1H, J = 3.6, 1.5 Hz), 7.18 (m, 2H), 7.08 (d, 1H,
J = 1.6 Hz), 4.12 (br, 2H) ppm. 13C NMR (151 MHz, CDCl3): δ 144.4,
144.2, 140.9, 135.0, 131.5, 128.1, 127.8, 125.9, 125.4, 124.9, 123.3, 119.4,
116.5, 113.2 ppm. MS (EI +): m/z 257 [M+, 100%]. HRMS (EI +)
calculated for [C14H11NS2]+: 257.03329. Found: 257.03344. FT-IR
(KBr): 3443 (br, w), 2924 (s), 2857 (w), 1612 (s), 1552(w), 1483
(m), 1427 (w), 1308 (w), 1260 (w), 1198 (w), 1088 (w), 1049 (w), 949
[Fe(6)2(NCS)2] (9). A solution of KSCN (73 mg, 0.75 mmol) in H2O
(10 mL) was sparged with N2 gas for 0.5 h and then combined with
Fe(II)SO4 7H2O (69 mg, 0.25 mmol). The mixture was stirred for an
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additional 0.5 h and then combined with a solution of 6 (170 mg,
0.50 mmol) in MeOH (50 mL), which was also sparged with N2 gas for
0.5 h. The solution was stirred under a N2 atmosphere for 72 h, con-
centrated to 20 mL, and cooled in an ice bath. The resulting green-blue
precipitate was collected by vacuum filtration and washed with water and
pentane and then dried. Yield: 220 mg (65%). Crystals suitable for X-ray
diffraction were grown by slow evaporation of 50:50 CH2Cl2/toluene
solutions of 9. MS (FAB +): m/z 864 [(M)+, 3%], 806 [(M ꢀ SCN)+,
27%], 460 [(M ꢀ C21H14N3S3)+, 100%]. FT-IR (KBr): 3066 (w), 2924
(w), 2852 (w), 2054 (s), 1625 (br, m), 1593 (s), 1483 (m), 1439 (m),
1301 (w), 1211 (w), 1120 (w), 955 (w), 910 (w), 817 (m), 773 (w), 698
(w), 839(w), 804 (s), 698 (s), 447 (w) cmꢀ1
.
(s) cmꢀ1. Recrystallized powder, calculated for C56H44N6S6Fe CH2Cl2
N-(Pyridin-2-ylmethylidene)-2,5-bis(thiophen-2-yl)aniline (6). Com-
pound 5 (245 mg, 0.95 mmol) was dissolved in 2 mL of DCM and
added dropwise to a solution of hexane (4 mL) containing 2-pyridine-
carboxaldehyde (150 mg, 1.40 mmol) at room temperature. The result-
ing yellow precipitate was collected by vacuum filtration, washed with
3
(found %): C, 60.37 (60.41); H, 4.09 (3.46); N, 7.42 (7.48). Precipitated
powder, calculated for C42H28N6S6Fe (found %): C, 58.34 (58.78); H,
3.27 (3.28); N, 9.73 (9.09). UVꢀvis (CH2Cl2): λmax (ε (Mꢀ1 cmꢀ1))
560 nm (1510).
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cool pentane, and dried. Yield: 190 mg (58%). Mp: 155ꢀ158 °C. H
poly-9. Prior to electropolymerization, 9 was dried under vacuum
conditions at room temperature for 72 h. Complex 9 (0.004 g,
4.63 μmol) was dissolved in anhydrous CH2Cl2 (2 mL) containing 0.5 M
supporting electrolyte (Bu4NPF6) and sparged with N2 gas for 20 min.
The solution was then subjected to successive oxidative sweeps at a scan
rate of 100 mV/S over a potential range of ꢀ0.5 to +1.0 V (vs ferrocene).
An orange film was deposited on the surface of the ITO (or platnium)
electrode. FT-IR (KBr pellet): 3449 (br, s), 2961 (w), 2924 (w), 2855
(w), 2667 (m), 1630 (br, s), 1464 (w), 1400 (w), 1261 (w), 1099 (br,
w), 1024 (br, w), 845 (br, m), 804 (w), 673 (w), 559 (w) cmꢀ1. UVꢀvis
(ITO): λmax 410 nm.
NMR (300 MHz, CDCl3): δ 8.78 (d, 1H, J = 4.7), 8.74 (s, 1H), 8.43
(d, 1H, J = 7.8), 7.93 (t, 1H, J = 7.7), 7.83 (d, 1H, J = 8.2), 7.60 (dd, 1H,
J = 8.2, 1.6), 7.51 (d, 1H, J = 3.7), 7.46 (m, 4H), 7.34 (d,1H, J = 5.0),
7.14 (m, 2H) ppm. 13C NMR (151 MHz, CDCl3): δ 161.2, 154.6,
149.7, 147.6, 143.4, 140.0, 136.8, 134.3, 128.4, 128.2, 127.6, 127.5, 126.8,
125.9, 125.4, 125.2, 124.2, 123.4, 122.5, 115.9 ppm. MS (EI +): m/z 346
[M+, 62%], 268 [(M ꢀ C5H4N)+, 100%]. HRMS (EI +) calculated
for [C20H14N2S2]+: 346.05984. Found: 346.06023. FT-IR (film, KBr):
3063 (w), 2916 (w), 1620 (m), 1582 (w), 1464 (m), 1431 (m), 1402
(w), 1352 (w), 1211 (w), 1119 (w), 978 (w), 897 (w), 874 (w), 852
(w), 817 (s), 781 (w), 700 (s), 617 (w), 478 (w) cmꢀ1. Calculated
for C20H14N2S2 (found %): C, 69.35 (69.41); H, 4.07 (4.31); N, 8.09
(7.87).
Scheme 1. Preparation of Ligand 4a
[Fe(2)2(NCS)2] (7). A solution of KSCN (201 mg, 2.06 mmol) in
MeOH (50 mL) was sparged with N2 gas for 0.5 h, combined with
Fe(II)SO4 7H2O (81 mg, 0.29 mmol). The mixture was stirred for an
3
additional 0.5 h and then combined with 2 (191 mg, 0.57 mmol). The
solution was stirred under a N2 atmosphere for 3 days, concentrated to
20 mL, and cooled in an ice bath. The resulting blue precipitate was
collected by vacuum filtration and washed with water and pentane and
dried. Yield: 210 mg (85%). Crystals suitable for X-ray diffraction were
grown by slow evaporation of 50:50 CH2Cl2/toluene solutions of 7.
MS (FAB +): m/z 840 [M+, 3%], 782 [(M ꢀ SCN)+, 24%], 448 [(M ꢀ
C25H18N3S)+, 100%]. FTIR (KBr): 2963 (m), 2850 (m), 2060 (s),
1591 (br, m), 1471 (m), 1440 (w), 1261 (s), 1098 (s), 1020 (s), 800
(s), 700 (m) cmꢀ1. Elemental analysis calculated (found) % for
a Reagents and conditions: (a) 3-thiopheneboronic acid, DME, H2O,
5 mol % Pd(PPh3)4, K2CO3, 95 °C, 72 h. (b) 2-pyridinecarboxaldehyde,
CH2Cl2, pentane.
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dx.doi.org/10.1021/ic2010503 |Inorg. Chem. 2011, 50, 7334–7343