W. Tan et al. / Journal of Organometallic Chemistry 694 (2009) 199–206
205
ane at ꢁ20 °C. M.p.: 101–102 °C. 1H NMR (CDCl3, 400 MHz, 23 °C) d
7.46, 7.29 and 7.20 (m each, 1:2:1 H, aromatic CH), 6.21 (s, 1H, Ind-
CH), 3.34 (br, 2H, Ind-CH2), 2.56 and 2.48 (t each, 2:2 H, 2 ꢂ CH2),
2.23 (s, 6H, 2 ꢂ Me), 1.87 (m, 2H, CH2); 13C{1H} NMR (CDCl3) d
145.56, 144.59, 144.36, and 142.22 (Cq), 127.73, 126.09, 124.63,
123.8 and 118.95 (CH), 115.00 (Cq, C4 of Pz), 37.83, 28.84, 27.38,
and 23.06 (4 ꢂ CH2), 11.04 (2 ꢂ Me). Anal. Calc. for C17H20N2: C,
80.91; H, 7.99; N, 11.10. Found: C, 81.22; H, 7.87; N, 11.01%.
4-(3-(1H-Inden-3-yl)propyl)-3,5-di-tert-butyl-1H-pyrazole (17).
In a fashion similar to synthesis of 16, a mixture of 2,2,6,6-tetra-
methyl-3,5-heptanedione (0.82 g, 4.4 mmol), 15 (1.00 g, 4.2 mmol),
potassium carbonate (0.61 g, 4.4 mmol), and potassium iodide
(0.37 g, 2.2 mmol) in 50 mL acetone was refluxed for 48 h to give
3-(3-indenylpropyl)-2,4-dione which was then reacted with hydra-
zine hydrate (85%, 0.25 mL, 4.2 mmol) in the presence of three drops
of concentrated hydrochloric acid in 15 mL refluxing ethanol for
18 h. The work-up procedure resulted in an oily material which
was recrystallized in acetone at ꢁ20 °C, affording 17 as colorless
crystals (0.62 g, 55 %). M.p.: 184–185 °C. 1H NMR (CDCl3, 400 MHz,
23 °C) d 7.50, 7.41, 7.33, and 7.25 (m each, 1:1:1:1 H, aromatic CH),
6.27 (s, 1H, Ind-CH), 3.37 (br, 2H, Ind-CH2), 2.75, 2.69, and 2.00 (m
each, 2:2:2 H, 3 ꢂ CH2), 1.38 (s, 18H, 6 ꢂ Me); 13C{1H} NMR (CDCl3)
d 153.69, 145.52, 144.58, 144.22, and 113.67 (Cq), 128.18, 126.09,
124.63, 123.87, 119.01 (CH), 37.82, 32.84 (Cq), 31.17, 30.39
(6 ꢂ Me), 28.42, 25.34. Anal. Calc. for C23H32N2: C, 82.09; H, 9.58;
N, 8.32. Found: C, 82.07; H, 9.60; N, 8.34%.
4-(3-(1H-Inden-3-yl)propyl)-3-methyl-5-phenyl-1H-pyrazole (18).
Alkylation of acetylbenzoylmethane (2.36 g, 14.6 mmol) with 15
(3.45 g, 14.6 mmol) in the presence of K2CO3 (2.42 g, 17.5 mmol)
and KI (1.21 g, 7.3 mmol) produced 150 which was directly reacted
with hydrazine hydrate (85%, 5.0 mL, 85.0 mmol) in refluxing eth-
anol (50 mL) to afford 18 as a light brown oil (2.40 g, 52%). 1H NMR
(CDCl3, 400 MHz, 23 °C) d 8.70 (br and s, 1H, NH), 7.49, 7.32, 7.30,
and 7.23 (m each, 3:3:2:1 H, aromatic CH), 6.14 (s, 1H, Ind-CH),
3.30 (d, 2H, Ind-CH2), 2.66 and 2.54 (m each, 2:2 H, 2 ꢂ CH2),
2.24 (s, 3H, Me), 1.90 (m, 2H, CH2); 13C{1H} NMR (CDCl3) d
145.99, 145.46, 144.60, 144.04, and 142.95 (Cq), 132.74 (Cq, i-Cq
of Ph), 128.67, 128.10, 127.80, 126.09, 124.59, 123.82, and 119.02
(CH), 115.64 (Cq, C4 of Pz), 37.80, 28.85, and 23.27 (3 ꢂ CH2),
10.88 (Me). Anal. Calc. for C22H22N2: C, 84.04; H, 7.05; N, 8.91.
Found: C, 84.08; H, 7.06; N, 8.84%.
through a short pad of celite. The filtrate was concentrated under
reduced pressure and the resulting crude product was purified by
flash silica gel column chromatography with toluene as the eluent,
affording complexes 20–25 as the products.
[CpNi{4-(1H-inden-3-yl)methyl-3,5-dimethylpyrazolato}2]2Ni (20).
A
mixture of nickelocene (126 mg, 0.67 mmol), 7 (150 mg,
0.67 mmol) and 10 mL toluene was refluxed for 3 h afforded com-
plex 20 as red crystalline solid (103 mg, 52%). M.p.: >182 °C, dec.
1H NMR (toluene-d8, 400 MHz, 23 °C) d 7.27 and 7.10 (m each,
12:4 H, aromatic CH), 5.50 (s, 10H, 2 ꢂ Cp), 4.54 (s, 4H, 2 ꢂ Ind-
CH), 3.30 and 2.85 (m each, 8:8 H, 8 ꢂ CH2), 2.29 and 2.10 (s each,
24H, 8 ꢂ Me); 13C{1H} NMR (toluene-d8) d 151.79, 151.40, 146.42,
145.67, and 145.03 (Cq), 129.00, 126.98, 124.61, and 119.76 (aro-
matic CH), 115.63 (Cq, C4 of Pz), 93.97 (Cp), 38.14 and 23.80
(CH2), 15.50 and 13.33 (Me). Anal. Calc. for C70H70N8Ni3: C,
70.10; H, 5.88; N, 9.34. Found: C, 70.20; H, 5.89; N, 9.37%.
[CpNi{4-(1H-inden-3-yl)methyl-3-methyl-5-phenylpyrazolato}2]2Ni
(21). In a fashion similar to synthesis of 20, a mixture of nickelo-
cene (132 mg, 0.70 mmol), 8 (200 mg, 0.70 mmol) and 10 mL tolu-
ene was refluxed for 2 h afforded complex 21 as red crystalline
solid (163 mg, 48%). M.p.: >162 °C, dec. 1H NMR (CDCl3, 400 MHz,
23 °C) d 7.44 and 7.21 (m each, 24:12 H, aromatic CH), 5.69 (br,
4H, Ind-CH), 4.30 (s, 10H, 2 ꢂ Cp), 3.38 and 3.19 (m each, 8:8 H,
8 ꢂ CH2), 2.28 (s, 12H, 4 ꢂ Me); 13C{1H} NMR (CDCl3) d 157.77,
151.57, 145.37, 144.69, and 144.30 (Cq), 136.17 (Cq, i-Cq of Ph),
130.65, 128.65, 127.92, 126.07, 124.63, 123.75, and 118.97 (CH),
115.73 (Cq, C4 of Pz), 93.75 (Cp), 37.5 and 23.01 (2 ꢂ CH2), 12.47
(Me). Anal. Calc. for C90H78N8Ni3: C, 74.67; H, 5.43; N, 7.74. Found:
C, 74.51; H, 5.40; N, 7.69%.
[CpNi{4-(2-(1H-inden-3-yl)ethyl)-3,5-dimethylpyrazolato}2]2Ni (22):
In a fashion similar to synthesis of 20, a mixture of nickelocene
(159 mg, 0.84 mmol), 13 (200 mg, 0.84 mmol) and 10 mL toluene
was refluxed for 3 h afforded complex 22 as a red solid (220 mg,
84%). Single crystals suitable for X-ray crystallographic determina-
tion were grown from recrystallization in toluene at ꢁ20 °C. M.p.:
198 °C. 1H NMR (CDCl3, 400 MHz, 23 °C) d 7.44, 7.25 and 7.17 (m
each, 4:4:8 H, aromatic CH), 6.09 (s, 4H, Ind-CH), 5.64 (s, 10H,
2 ꢂ Cp), 3.27 (br, 8H, 4 ꢂ Ind-CH2), 2.49 and 2.37 (m each, 8:8 H,
8 ꢂ CH2), 2.15 (s, 8 ꢂ Me); 13C{1H} NMR (CDCl3) d 150.41, 150.27,
145.43, 144.51, and 144.43 (Cq), 127.86, 126.03, 124.49, 123.77,
and 118.93 (CH), 117.92 (Cq, C4 of Pz), 93.12 (Cp), 37.78, 29.84,
and 23.44 (3 ꢂ CH2), 14.68 and 12.15 (2 ꢂ Me). Anal. Calc. for
C74H78N8Ni3.2PhMe: C, 73.41; H, 6.58; N, 7.78. Found: C, 73.01;
H, 6.56; N, 7.75%.
[CpNi{4-(3-(1H-inden-3-yl)propyl)-3,5-dimethylpyrazolato}2]2Ni
(23). In a fashion similar to synthesis of 20, a mixture of nickelo-
cene (150 mg, 0.79 mmol), 16 (200 mg, 0.79 mmol) and 10 mL tol-
uene was refluxed for 5 h to afford complex 23 as a red solid
(203 mg, 78%). Single crystals suitable for X-ray crystallographic
determination were grown from recrystallization in hexane/CH2Cl2
(v/v, 5/1) at ꢁ20 °C. M.p.: 172 °C. 1H NMR (CDCl3, 400 MHz, 23 °C) d
7.39, 7.27 and 7.15 (m each, 1:1:2 H, aromatic CH), 5.96 (s, 4H,
4 ꢂ Ind-CH), 5.63 (s, 10H, 2 ꢂ Cp), 3.14 (br, 8H, 4 ꢂ Ind-CH2),
2.21, 2.14, and 1.47 (br each, 24H, 12 ꢂ CH2), 2.07 (s, 24H,
8 ꢂ Me); 13C{1H} NMR (CDCl3) d 150.30, 145.60, 144.56, and
144.42 (Cq), 127.47, 125.90, 124.43, 123.74, and 118.8 (CH),
118.08 (Cq, C4 of Pz), 93.09 (Cp), 37.64, 29.54, 27.09 and 24.27
(CH2), 14.82 and 12.16 (Me). Anal. Calc. for C78H86N8Ni3: C,
71.42; H, 6.61; N, 8.54. Found: C, 71.72; H, 6.65; N, 8.49%.
[CpNi{4-(3-(1H-inden-3-yl)propyl)-3methyl-5-phenylpyrazolato}2]2-
Ni (24). In a fashion similar to synthesis of 20, a mixture of
nickelocene (135 mg, 0.71 mmol), 18 (224 mg, 0.71 mmol) and
10 mL toluene was refluxed for 2 h to afford complex 24 as a red
solid (105 mg, 38%). M.p.: >142 °C, dec. 1H NMR (CDCl3, 400 MHz,
23 °C) d 7.50 and 7.17 (m each, 24:12 H, aromatic CH), 5.95 (s,
4H, 4 ꢂ Ind-CH), 4.24 (s, 10H, 2 ꢂ Cp), 3.17 (br, 8H, Ind-CH2),
4-(3-(1H-Inden-3-yl)propyl)-3,5-diphenyl-1H-pyrazole
(19).
Alkylation of dibenzoylmethane (3.80 g, 16.9 mmol) with 15
(4.00 g, 16.9 mmol) in the presence of K2CO3 (2.34 g, 16.9 mmol)
and KI (1.40 g, 8.4 mmol) produced 150 which was directly reacted
with hydrazine hydrate (85%, 3.0 mL, 50.9 mmol) in the presence
of three drops of 37% hydrochloric acid in refluxing ethanol
(50 mL) to afford 19 as a pale yellow solid (3.46 g, 54%). Colorless
crystals were obtained by recrystallization from acetone and hex-
ane (v/v, 1:3) at ꢁ20 °C. M.p.: 154 °C. 1H NMR (CDCl3, 400 MHz,
23 °C) d 7.54, 7.44, 7.36, 7.22 and 7.13 (m each, 4:1:6:2:1 H, aro-
matic CH), 5.99 (s, 1H, Ind-CH), 3.23 (d, 2H, Ind-CH2), 2.85 and
2.46 (t each, 2:2 H, 2 ꢂ CH2), 1.84 (m, 2H, CH2); 13C{1H} NMR
(CDCl3) d 146.73 (Cq and br), 145.38, 144.58, and 143.74 (Cq),
132.30 (Cq, i-Cq of Ph), 128.78, 128.32, 128.12, 127.98, 126.06,
124.52, 123.77, and 119.06 (CH), 115.86 (Cq, C4 of Pz), 37.74,
28.72, 27.61, and 23.34 (4 ꢂ CH2). Anal. Calc. for C27H24N2: C,
86.13; H, 6.43; N, 7.44. Found: C, 86.02; H, 6.48; N, 7.38%.
4.8. Synthesis of complexes [CpNi{Ind-(CH2)n-Pz}2]2Ni (20–24) and
[CpNi{Ind-(CH2)3-Pz}]2 (25) – a general procedure
A mixture of nickelocene (Cp2Ni) and an indenyl-pyrazole in 1:1
molar ratio was stirred in refluxing toluene, forming a deep-red
solution. All the volatiles were removed under reduced pressure
and the resultant residue was extracted with toluene, filtered