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was added to a solution of BPMEN (0.14 g, 0.5 mmol) in (0.18 g, 0.50 mmol), 5-methoxysalicylic acid (5-OMeSA-H;
methanol (3 mL) and the resulting mixture was allowed to stir 0.08 g, 0.50 mmol), and triethylamine (70 μL) in 5 mL of
for 2 min. To the light yellow solution, gentisic acid and tri- methanol were stirred under a nitrogen atmosphere for 6 h.
ethylamine (0.5 mmol, 70 μL) dissolved in 2 mL of methanol The solution was concentrated to 1 mL, and diethyl ether
were added. The resulting green solution was then allowed to (10 mL) was added. The mixture was then stirred for another
stir under nitrogen atmosphere for 6 h. The solution was dried 2 h to give a light green solid of the perchlorate salt of the
under reduce pressure, filtered after addition of dichloro- complex ([(BPMEN)FeII(5-OMeSA)](ClO4)). A methanolic solu-
methane (5 mL) and the filtrate was concentrated to 1 mL. tion of sodium tetraphenylborate (0.17 g, 0.50 mmol) was
Diethyl ether (10 mL) was added to the concentrated reaction added to the methanolic reaction solution to precipitate a
solution and the mixture was then stirred for another 2 h to light green solid. The solid was isolated by filtration, washed
obtain a light green solid of the perchlorate salt of the with methanol, and dried. Yield: 0.25 g (62%). Anal. Calcd for
complex 2. Pure crystalline complex was obtained by recrystal- C48H49BFeN4O4 (812.58 g mol−1): C, 70.95; H, 6.08; N, 6.89.
lization from a solvent mixture of dichloromethane and Found C, 70.70; H, 6.22; N, 6.73. IR (KBr, cm−1): 3483(br),
hexane (1 : 2). Yield: 0.20
g
(68%). Anal. Calcd for 33 138(m), 3053(s), 3001(m), 2926(m), 2858(m), 1734(m),
C23H27ClFeN4O8 (578.78 g mol−1): C, 47.73; H, 4.70; N, 9.68. 1632(m), 1605(s), 1576(vs), 1481(vs), 1441(s), 1377(m),
Found C, 47.42; H, 4.55; N, 9.76. IR (KBr, cm−1): 3429(br), 1302(m), 1263(m), 1126(m), 1030(m), 978(m), 816(m), 739(vs),
3134(m), 3053(s), 2986(m), 2924(s), 2855(m), 1744(m), 707(vs), 665(m), 613(m), 471(m), 366(m). 1H NMR (500 MHz,
1663(m), 1605(s), 1578(s), 1477(vs), 1447(vs), 1387(s), 1302(m), CD3CN, 298 K): δ 140.06, 113.61, 80.13, 48.95, 41.83, 21.53,
1240(m), 1148(s), 1121(s), 1101(s), 1063(s), 1026(s), 812(m), 12.63, 10.01, 7.29, 7.00, 6.85, 4.04 ppm. UV-vis (CH3CN); λ, nm
750(vs), 706(vs), 610(m), 467(m). UV-vis (CH3CN); λ, nm (ε, M−1 (ε, M−1 cm−1): 325 (3940).
cm−1): 325 (3100). 1H NMR (500 MHz, CD3CN, 298 K): δ
128.30, 109.28, 104.84, 101.80, 85.73, 75.91, 70.23, 51.63, TBimA (0.20 g, 0.5 mmol) and iron(II) perchlorate hexahydrate
(0.18 g, 0.5 mmol) in methanol (5 mL), a mixture of gentisic
[(TBimA)FeII(GN-H)](GN) (3). To a stirring solution of the
45.35, 42.38, 8.57, 7.82, 7.36, 4.43, −6.71 ppm.
[(BPMEN)FeII(DHN-H)](ClO4) (2a). Complex 2a was syn- acid (0.15 g, 0.5 mmol) and triethylamine (70 μL, 0.5 mmol) in
thesized according to the procedure described for complex 2 methanol (5 mL) was added dropwise. The resulting solution
except that 1,4-dihydroxy-2-naphthoic acid (0.5 mmol) was was allowed to stir for 6 h to precipitate an off-white solid. The
added instead of gentisic acid. The complex was isolated in solid was filtered and washed several times with methanol. Yield:
pure form by recrystallization from a solvent mixture of di- 0.16 g (42%). Anal. Calcd for C38H31FeN7O8 (769.54 g mol−1): C,
chloromethane and hexane (1 : 2). Yield: 0.20
g (64%). 59.31; H, 4.06; N, 12.74. Found C, 59.73; H, 4.05; N, 12.90. IR
Elemental analysis calcd (%) for C27H29ClFeN4O8 (628.84 g (KBr, cm−1): 3431(br), 3198(m), 3123(m), 3059(m), 2926(m),
mol−1): C 51.57, H 4.65, N 8.91; Found: C 51.28, H 5.01, N 2779(m), 1622(m), 1574(s), 1450(vs), 1385(s), 1340(m), 1277(m),
8.87; IR (KBr): 3431(br), 3242(br), 3067(m), 29 749 (m), 1240(m), 1144(s), 1117(vs), 1088(s), 1045(m), 1001(m), 962(m),
2932(m), 2677(s), 2490(m), 1661(m), 1587(vs), 1472(m), 1439 889(m), 835(m), 748(vs), 681(m), 631(vs), 559(m), 434(m). UV-vis
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(vs), 1327(s), 1229(m), 1146(vs), 1090(vs), 1022(m), 976(m), (CH3CN); λ, nm (ε, M−1 cm−1): 330 (4330). H NMR (500 MHz,
814(s), 768(vs), 629(vs), 592(m), 467(m) cm−1; ESI-MS (positive CD3CN, 298 K): δ 67.25, 56.72, 40.32, 26.09, 16.18, 12.80, 7.51,
ion mode in CH3CN): m/z (%) 528.87 (C27H29FeN4O4 expected 7.32, 6.72, 6.27, 4.49, 3.63 ppm.
at m/z 529.15 for [(BPMEN)FeII(DHN-H)]+). UV-vis (CH3CN); λ,
[(TBimA)FeII(DHN-H)](ClO4) (3a). Complex 3a was syn-
nm (ε, M−1 cm−1): 360 (6080). 1H NMR (500 MHz, CD3CN, thesized according to the procedure described for complex 2
298 K): δ 141.58, 118.34, 109.63, 79.94, 50.66, 43.58, 11.45, except that 1,4-dihydroxy-2-naphthoic acid (0.5 mmol) was
8.27, 7.83, 7.36, 7.23, 6.54, 6.22, 4.36, 3.43 ppm.
added instead of gentisic acid and TBimA was used in place of
[(BPMEN)FeII(HNA)](ClO4) (2b). Complex 2b was synthesized BPMEN. Single crystals of 3a suitable for X-ray diffraction were
according to the procedure described for complex 2a except isolated by recrystallization from a solvent mixture of dichloro-
that 1-hydroxy-2-naphthoic acid (HNA-H) (0.09 g, 0.5 mmol) methane and methanol (1 : 2). Yield: 0.26 g (69%). Anal. Calcd
was used instead of DHN-H2. An off-white crystalline solid was for C35H28ClFeN7O8 (765.94 g mol−1): C, 54.88; H, 3.68; N,
isolated by recrystallization from a solvent mixture of dichloro- 12.80. Found C, 54.12; H, 3.84; N, 12.41. IR (KBr, cm−1): 3356
methane and hexane (1 : 2). Yield: 0.20 g (65%). Anal. Calcd for (br), 3063(m), 2924(m), 2853(m), 1624(m), 1587(s), 1452(vs),
C27H29ClFeN4O7 (612.84 g mol−1): C, 52.92; H, 4.77; N, 9.14. 1435(s), 1418(s), 1391(m), 1337(s), 1315(s), 1231(m), 1115(vs),
Found C, 52.74; H, 5.03; N, 9.39. IR (KBr, cm−1): 3420(br), 1092(vs), 1043(m), 1003(m), 849(m), 750(vs), 625(m), 594(m),
3064(m), 2926(s), 2856(m), 2679(m), 1605(vs), 1585(vs), 1441 440(m). ESI-MS (positive ion mode, acetonitrile): m/z 666.34
(vs), 1400(vs), 1302(m), 1144(vs), 1115(vs), 1090(vs), 1022(m), (C35H28FeN7O4 expected at m/z 666.49 for [(TBimA)
978(m), 806(m), 773(m), 731(m), 662(m), 631(m), 581(m), FeII(DHN-H)]+), 408.31 (C24H22N7 expected at m/z 408.48 for
1
469(m), 378(m). H NMR (500 MHz, CD3CN, 298 K): δ 107.75, [(TBimA) + H]+). UV-vis in acetonitrile; λ, nm (ε, M−1 cm−1):
1
88.64, 60.51, 28.35, 15.91, 8.52, 8.24, 7.76, 7.35, 7.18, −5.92, 340 (5560). H NMR (500 MHz, CD3CN, 295 K): δ 58.11, 41.02,
−22.17 ppm. UV-Vis (CH3CN); λ, nm (ε, M−1 cm−1): 335 (4860).
[(BPMEN)FeII(5-OMeSA)](BPh4) (2c). Equimolar amounts of
26.44, 17.20, 10.41, 9.77, 8.48, 7.97, 7.27, 6.50, 3.41 ppm.
Analysis of organic products after the reaction of iron(II)–
BPMEN (0.14 g, 0.5 mmol), iron(II) perchlorate hexahydrate DHN complexes with dioxygen. Each of the iron(II) complexes
This journal is © The Royal Society of Chemistry 2019
Dalton Trans., 2019, 48, 16993–17004 | 17001