Article
Organometallics, Vol. 30, No. 5, 2011 933
131.52, 126.58, 125.35, (Ar), 44.54, 43.27, 41.74, 40.20, 37.49, 37.23,
31.72, 30.95, 29.43, 23.30, (C). Anal. Calcd for C17H20O: C, 84.96;
H, 8.39; N, 6.66. Found: C, 84.98; H, 8.35; N, 6.65.
25 °C. Immediate methane evolution was observed, which
ceased within 5-10 min. The resulting red solution was stirred
for an additional 4 h at 25 °C, during which time excess
[(pyridine)2NiMe2] decomposed to nickel black. The resulting
mixture was filtrated to remove nickel black, the residue was
extracted with toluene, and all volatiles were removed under
reduced pressure to yield pure samples of pyridine complex 5a as
a red powder in a high yield (92%). Complexes 5b and 6a,b were
prepared using the same procedure with similar yields.
Synthesis of Ligands 3a,b. To a slurry of 3.3 g of potassium
tert-butoxide (1.5 equiv) in anhydrous diethyl ether (40 mL)
were added 4.4 g of 2a (20 mmol) and 2.9 g of ethyl formate (2.0
equiv) at 0 °C. Immediately a large amount of white solid
appeared in the reaction bottle, and the mixture was stirred
for 30 min at 0 °C. Then the resulting suspension was warmed to
room temperature and stirred for about 10 h. The white solid
was separated by filtration and dried under reduced pressure.
Formic acid in ethanol was added to the solid until the pH was
<7, affording the corresponding β-diketone, which was used
directly in the preparation of ligand 3a. Subsequently, 3.5 g of
2,6-diisopropylaniline (1.0 equiv) was added to the obtained β-
diketone in ethanol and the condensation reaction was carried
out for about 24 h, yielding 4.2 g of ligand 3a (51%). Ligand 3b
was prepared according to the same method as 3a.
[(2,6-iPr2C6H3)NdCHC16H10O]Ni(Me)(Py) (5a). 1H NMR
(300 MHz, C6D6): δ 7.96 (m, 2H, o-H Py), 7.44 (d, J=5.4 Hz,
1H, Ar-H), 7.29 (s, 4H, Ar-H, NCH), 7.25 (s, 1H, Ar-H),
7.18-7.10 (m, 4H, Ar-H), 7.02 (d, J=5.1 Hz, 2H, Ar-H), 6.69
(t, J=5.7 Hz, 1H, p-H Py), 6.26 (t, J=5.4 Hz, 2H, m-H Py), 4.57
(sept, 3JHH=5.1 Hz, 2H, iPr-CH), 2.73 (m, 2H, CH2), 2.49 (m,
2H, CH2), 1.72, 1.41, (d, 3JHH=5.1 Hz, 12H, iPr-CH3), -0.62 (s,
3H, NiCH3). 13C NMR (300 MHz, C6D6): δ 169.93 (NC),
160.44, 151.96, 151.68, 151.41, 144.37, 142.70, 142.41, 140.71,
134.90, 130.69, 129.43, 127.78, 126.78, 126.23, 125.85, 123.62,
123.24, (Ar, Py), 105.41 (dC), 31.69, 27.25, (CH2), 28.65 (iPr-
CH), 25.35, 23.71, (iPr-CH3), -6.23 (Ni-CH3). Anal. Calcd for
C35H38N2NiO: C, 74.88; H, 6.82; N, 4.99. Found: C, 74.85; H,
6.79; N, 5.01.
1
(2,6-iPr2C6H3)NdCHC16H12OH (3a). H NMR (300 MHz,
3
CDCl3): δ 11.08 (d, JHH = 12.0 Hz, 1H, N-H), 7.40-7.11(m,
11H, Ar-H), 6.72 (d, J=12.0 Hz, 1H, NCH), 3.17 (sept, 3JHH
=
6.9 Hz, 2H, iPr-CH), 2.92 (t, 3JHH=6.6 Hz, 2H, CH2), 2.59 (t,
3JHH=6.6 Hz, 2H, CH2), 1.16 (d, 3JHH=6.9 Hz, 12H, iPr-CH3).
13C NMR (300 MHz, CDCl3): δ 188.09 (NC), 150.99, 145.41,
144.08, 143.95, 143.32, 137.30, 134.73, 130.87, 130.71, 129.10,
128.21, 127.82, 127.58, 126.90, 124.10, (Ar), 104.91 (C), 32.05,
28.12, (CH2), 28.78 (iPr-CH), 24.27 (iPr-CH3).
[(2,6-iPr2C6H3)NdCHC17H16O]Ni(Me)(Py) (5b). Yield: 90%.
1H NMR (300 MHz, C6D6): δ 8.75 (m, 2H, o-H Py), 7.25-6.96
(m, 7H, Ar-H, NCH), 6.70 (m, 1H, p-H Py), 6.28 (m, 2H, m-H
Py), 4.72, 4.49 (sept, 3JHH=6.9 Hz, 2H, iPr-CH), 3.43 (m, 1H,
ArCH), 2.90-0.94 (m, 14H, CH, CH2), 1.77, 1.68 (d, 3JHH=6.9
(2,6-iPr2C6H3)NdCHC17H18OH (3b). Yield: 61%. 1H NMR
i
3
i
3
Hz, 6H, Pr-CH3), 1.36, 1.23 (dd, JHH =6.9, 4.2 Hz, 6H, Pr-
CH3), -0.46 (s, 3H, NiCH3). 13C NMR (300 MHz, C6D6): δ
172.21 (NC), 160.79, 152.21, 151.75, 150.06, 144.65, 143.83,
142.85, 142.66, 142.51, 135.89, 130.89, 125.93, 125.44, 124.74,
124.20, 123.62, (Ar, Py), 105.41 (dC), 44.50, 43.97, 43.47, 41.37,
40.99, 40.56, 37.75, 37.35, 36.96, 32.62, 31.33, 30.30, 30.13,
29.64, 28.89, 28.74, 28.61, 28.38, 27.69, 25.35, 25.23, 24.10,
23.74, 23.65, (C), -5.80 (Ni-CH3). Anal. Calcd for
C36H42N2NiO: C, 74.88; H, 7.33; N, 4.85. Found: C, 74.90;
H, 7.30; N, 4.88.
(300 MHz, CDCl3): δ 11.42 (d, JHH = 12.0 Hz, 1H, N-H),
7.52-6.98(m, 6H, Ar-H), 6.74 (d, J=12.0 Hz, 1H, NCH), 3.95
(m, 1H, ArCH), 3.28 (sept, 3JHH=6.9 Hz, 2H, iPr-CH), 2.82 (m,
2H, CH2), 2.44 (m, 2H, CH2), 2.35 (m, 1H, CH), 1.97 (m, 1H,
CH), 1.63-1.55 (m, 6H, CH2), 1.23 (d, 3JHH=6.9 Hz, 12H, iPr-
CH3), 0.86 (m, 2H, CH2). 13C NMR (300 MHz, CDCl3): δ
190.37 (NC), 150.33, 149.37, 144.88, 143.90, 130.67, 127.37,
125.64, 125.43, 124.27, 124.11, (Ar), 105.85 (C), 44.10, 43.40,
40.82, 37.59, 37.27, 32.50, 31.07, 29.52, 28.76, 28.14, 24.33,
24.26, (C).
Synthesis of Ligands 4a,b. To a 100 mL bottle were added 0.4 g
of compound 3a (1 mmol) and 0.24 g of DDQ (1.04 mmol)
followed by 5 mL of dioxane, forming a dark mixture. Then the
mixture was stirred at the refluxing temperature for 1 h, and a
yellow solution formed. The solution was cooled to room
temperature, followed by filtration to remove the solid residue.
Subsequently, the solvent was evaporated and the product was
purified via column chromatography on silica gel, affording 0.2
g (50%) of yellow solid 4a at room temperature. Ligands 4b was
prepared acording to the same method as 4a with a similar yield.
[(2,6-iPr2C6H3)NdCHC16H10O]Ni(Me)(Py) (6a). Yield: 94%.
1H NMR (300 MHz, CDCl3): δ 8.11 (m, 2H, o-H Py), 7.71 (s,
1H, NCH), 7.62 (d, J=6.0 Hz, 1H, Ar-H), 7.37 (m, 1H, Ar-H),
7.31 (m, 1H, Ar-H), 7.24-7.05 (m, 6H, Ar-H), 6.88 (t, J=5.7
Hz, 2H, Ar-H), 6.72 (t, J=5.7 Hz, 2H, Ar-H), 6.68 (t, J=5.7
Hz, 1H, p-H Py), 6.25 (t, J=5.4 Hz, 2H, m-H Py), 4.37 (sept,
3JHH=5.1 Hz, 2H, iPr-CH), 1.64, 1.29, (d, 3JHH=5.1 Hz, 12H,
iPr-CH3), -0.67 (s, 3H, NiCH3). 13C NMR (300 MHz, C6D6): δ
167.83 (NC), 164.94, 151.82, 150.74, 145.36, 142.52, 141.65,
139.88, 135.03, 130.74, 129.71, 129.09, 127.03, 126.52, 125.70,
123.81, 123.66, 114.94, 114.60, (Ar, Py), 28.76 (iPr-CH), 25.17,
23.55, (iPr-CH3), -5.86 (Ni-CH3). Anal. Calcd for
C35H36N2NiO: C, 75.15; H, 6.49; N, 5.01. Found: C, 75.13;
H, 6.52; N, 4.98.
1
(2,6-iPr2C6H3)NdCHC16H10OH (4a). H NMR (300 MHz,
CDCl3): δ 14.45 (s, 1H, O-H), 8.16 (s, 1H, NCH), 7.75 (dd, J=
6.0, 0.9 Hz, 1H, Ar-H), 7.57 (t, J=6.0 Hz, 1H, Ar-H), 7.47-7.34
(m, 6H, Ar-H), 7.29-7.27 (m, 2H, Ar-H), 7.22-7.14 (m, 3H, Ar-
H), 2.98 (sept, 3JHH=5.4 Hz, 2H, iPr-CH), 1.14 (d, 3JHH=5.4
[(2,6-iPr2C6H3)NdCHC17H16O]Ni(Me)(Py) (6b). Yield:
i
1
Hz, 12H, Pr-CH3). 13C NMR (300 MHz, CDCl3): δ 165.00
92%. H NMR (300 MHz, CDCl3): δ 8.75 (m, 2H, o-H Py),
(NC), 144.91, 142.22, 140.87, 138.31, 130.10, 129.34, 128.83,
128.37, 127.98, 127.40, 126.62, 123.77, 118.26, (Ar), 28.57 (iPr-
CH), 24.06 (iPr-CH3).
7.71 (s, 1H, NCH), 7.57 (dd, J = 5.1, 1.8 Hz, 1H, Ar-H),
7.46-7.39 (m, 3H, Ar-H), 7.24-7.05 (m, 4H, Ar-H), 6.77 (t,
J=5.7 Hz, 1H, p-H Py), 6.36 (t, J=5.4 Hz, 2H, m-H Py), 4.49,
4.37 (sept, 3JHH=5.1 Hz, 2H, iPr-CH), 3.75 (dd, J=6.6, 3.9 Hz,
1H, ArCH), 2.50 (b, 1H, CH), 2.19 (b, 1H, CH), 1.74, 1.63 (d,
3JHH=5.1 Hz, 6H, iPr-CH3), 1.59-1.34 (m, 6H, CH2), 1.29, 1.26
(d, 3JHH =5.1 Hz, 6H, iPr-CH3), 1.01 (m, 2H, CH2), -0.52 (s,
3H, NiCH3). 13C NMR (300 MHz, C6D6): δ 169.69 (NC),
165.35, 152.39, 150.79, 148.40, 141.80, 140.84, 136.04, 130.34,
126.67, 126.53, 123.92, 123.84, 123.71, 122.13, 115.52, 115.17,
(Ar, Py), 45.03, 41.52, 40.86, 37.99, 37.29, 30.36, 30.25, 29.90,
28.84, 28.71, 25.20, 25.04, 23.64, 23.50, (C), -5.37 (Ni-CH3).
Anal. Calcd for C36H44N2NiO: C, 74.62; H, 7.65; N, 4.83.
Found: C, 74.65; H, 7.67; N, 4.86.
(2,6-iPr2C6H3)NdCHC17H16OH (4b). Yield: 45%. 1H NMR
(300 MHz, CDCl3): δ 8.17 (s, 1H, NCH), 7.53-7.44 (m, 3H, Ar-
H), 7.22 (m, 3H, Ar-H), 7.17-7.12 (m, 2H, Ar-H), 4.41 (m, 1H,
3
i
ArCH), 3.10 (sept, JHH = 5.4 Hz, 2H, Pr-CH), 2.35 (b, 1H,
CH), 2.07 (m, 1H, CH), 1.69-1.55 (m, 6H, CH2), 1.22 (d, 3JHH
=
5.4 Hz, 12H, iPr-CH3), 0.86 (m, 2H, CH2). 13C NMR (300 MHz,
CDCl3): δ 169.41 (NC), 165.26, 148.37, 143.61, 140.90, 139.20,
129.17, 127.82, 126.55, 126.27, 123.86, 123.69, 118.84, 112.38,
(Ar), 45.84, 43.39, 40.44, 37.83, 37.15, 31.07, 29.72, 28.72, 24.10,
24.04, (C).
Synthesis of Complexes 5a,b, 6a,b, and 7a,b. To [(pyridine)2-
NiMe2] (0.27 g, 1.1 mmol) and the ligand 3a (1.0 mmol) in a 100
mL septum-capped Schlenk bottle was added toluene (15 mL) at
[(2,6-iPr2C6H3)NdCHCHC(C6H4)O]Ni(Me)(Py) (7a). Yield:
96%. 1H NMR (300 MHz, CDCl3): δ 8.65 (d, J=5.1 Hz, 2H,