Article
Organometallics, Vol. 29, No. 10, 2010 2313
135.58, 134.38, 130.46, 126.75, 126.20, 125.66, 125.46, 122.82,
122.68, 114.88, (Ar), 101.70 (dC), 29.02, 26.34, (CH2), 27.28 (iPr
CH), 22.80 (iPr CH3). Anal. Calcd for C23H27NO: C, 82.84; H,
8.16; N, 4.20. Found: C, 82.87; H, 8.12; N, 4.24.
7.37 (d, J = 9.3 Hz, 1H, NdCH), 7.12-6.77 (m, 18H, Ar H),
6.41-6.32 (m, 3H, Ar H), 4.26 (sept, 3JHH = 5.1 Hz, 2H, iPr CH),
2.63 (t, J = 5.1 Hz, 2H, CH2), 2.04 (t, J = 5.1 Hz, 2H, CH2), 1.86
(quint, J = 5.1 Hz, 2H, CH2), 1.36, 1.23, (d, 3JHH = 5.1 Hz, 12H,
iPr CH3). 13C NMR (300 MHz, C6D6): δ 174.29 (NC), 162.62,
151.42, 147.44, 141.61, 141.44, 139.08, 138.05, 134.45, 134.32,
132.17, 131.61, 129.41, 125.87, 125.29, 125.14, 122.51, 121.27,
(Ar), 104.74 (dC), 33.41, 31.84, 28.21, (CH2), 28.75 (iPr CH),
25.77, 22.74, (iPr CH3). Anal. Calcd for C48H48NNiOP: C, 77.43;
H, 6.50; N, 1.88. Found: C, 77.48; H, 6.44; N, 1.93.
1
(2,6-iPr2C6H3)NdCHC5H6(C6H4)OH (5c). Yield: 60%. H
NMR (300 MHz, CDCl3): δ 11.46 (d, J = 11.1 Hz, 1H, NH),
7.66 (d, J = 7.2 Hz, 1H, Ar H), 7.40-7.16 (m, 6H, Ar H), 6.74 (d,
J = 11.1 Hz, 1H, NdCH), 3.27 (sept, 3JHH = 6.6 Hz, 2H, iPr
CH), 2.77 (t, 3JHH = 6.6 Hz, 2H, CH2), 2.12 (t, 3JHH = 6.6 Hz,
3
2H, CH2), 1.92 (quint, JHH = 6.6 Hz, 2H, CH2), 1.25 (d,
3JHH = 6.9 Hz, 12H, iPr CH3). 13C NMR (300 MHz, CDCl3): δ
195.54 (NC), 150.92, 143.40, 140.75, 137.79, 135.63, 129.38,
127.43, 126.48, 126.23, 125.59, 122.75, (Ar), 104.81 (dC), 30.03,
29.95, 26.62, (CH2), 27.39 (iPr CH), 22.78 (iPr CH3). Anal. Calcd
for C24H29NO: C, 82.95; H, 8.41; N, 4.03. Found: C, 82.99; H,
8.38; N, 4.07.
Synthesis of Complexes 7a-c.17c To [(pyridine)2NiMe2] (0.27 g,
1.1 mmol) and the ligand 6a (1.0 mmol) in a 100 mL septum-capped
Schlenk bottle was added toluene (15 mL) at 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 7a as a red powder in high yield (95%).
Synthesis of Complexes 3b and 6a-c. A solution of ligand 2
(0.29 g, 1.0 mmol) in THF (15 mL) was added to sodium hydride
(48 mg, 2.0 mmol). Immediately a large amount of bubbles were
emitted from the mixture and a yellow solution formed. Then
the solution was stirred at room temperature for 4 h, filtered,
and evaporated. The solid residue was washed with hexane
(20 mL) and dried under vacuum, affording a light yellow
sodium salt. The sodium salt was dissolved in toluene at room
temperature and transferred to a toluene solution of trans-
PhNi(PPh3)2Cl (0.7 g, 1.0 mmol) in a Schlenk flask with stirring
at room temperature for 12 h, forming a red solution. Then the
reaction mixture was filtered by cannula filtration and the
filtrate was concentrated in vacuo to about 4 mL, to which
hexane (15 mL) was added. Subsequently, yellow crystals pre-
cipitated from the solution, which were isolated via filtration
and washed several times with cold hexane to yield 0.35 g (51%)
of complex 3b. The other neutral nickel(II) complexes 6a-c were
prepared by the same procedure with similar yields.
[(2,6-iPr2C6H3)NdCHC3H2O(C6H4)]Ni(CH3)(Py) (7a). 1H
NMR (300 MHz, C6D6): δ 8.72 (m, 2H, o-H Py), 7.65 (d, J =
6.9 Hz, 1H, Ar H), 7.20-7.17 (m, 6H, Ar H), 7.07 (s, 1H,
NdCH), 6.62 (m, 1H, p-H Py), 6.24 (t, J = 6.6 Hz, m-H Py), 4.45
(sept, 3JHH = 6.9 Hz, 2H, iPr CH), 3.31 (s, 1H, CH2), 1.62, 1.23,
(d, 3JHH = 6.9 Hz, 12H, iPr CH3), -0.53 (s, 3H, NiCH3). 13
C
NMR (300 MHz, C6D6): δ 175.72 (NC), 157.86, 152.18, 151.86,
146.02, 142.60, 135.70, 128.74, 126.85, 125.99, 125.42, 123.64,
123.31, 121.39, (Ar, Py), 107.56 (dC), 32.68 (CH2), 28.59 (iPr
CH), 25.31, 23.64, (iPr CH3), -6.61 (Ni-CH3). Anal. Calcd for
C29H34N2NiO: C, 71.36; H, 6.84; N, 5.94. Found: C, 71.33; H,
6.81; N, 5.96.
[(2,6-iPr2C6H3)NdCHC4H4O(C6H4)]Ni(CH3)(Py) (7b). Yield:
92%. 1H NMR (300 MHz, C6D6): δ 8.70 (m, 2H, o-H Py), 7.77
(m, 1H, Ar H), 7.19 (s, 3H, Ar H), 7.08-6.92 (m, 4H, Ar H,
NdCH), 6.60 (m, 1H, p-H Py), 6.22 (t, J = 6.9 Hz, m-H Py), 4.45
(sept, 3JHH = 6.9 Hz, 2H, iPr CH), 2.66 (m, 2H, CH2), 2.44 (m,
2H, CH2), 1.61, 1.24, (d, 3JHH = 6.9 Hz, 12H, iPr CH3), -0.54 (s,
3H, NiCH3). 13C NMR (300 MHz, C6D6): δ 168.05 (NC), 161.21,
151.72, 151.27, 142.13, 140.16, 135.81, 135.42, 129.09, 126.31,
125.63, 125.42, 123.25, 122.91, (Ar, Py), 101.99 (dC), 30.05,
26.65, (CH2), 28.19 (iPr CH), 24.93, 23.21, (iPr CH3), -6.59
(Ni-CH3). Anal. Calcd for C29H34N2NiO: C, 71.77; H, 7.06; N,
5.77. Found: C, 71.81; H, 7.03; N, 5.74.
[(2,6-iPr2C6H3)NdCHC6H8O]Ni(Ph)(PPh3) (3b). 1H NMR
(300 MHz, C6D6): δ 7.66-7.60 (m, 6H, Ar H), 7.25 (d, J = 9.3 Hz,
1H, NdCH), 7.09-6.86 (m, 14H, Ar H), 6.41-6.31 (m, 3H, Ar H),
4.18 (sept, 3JHH = 6.9 Hz, 2H, iPr CH), 2.30 (t, J = 5.7 Hz, 2H,
CH2), 1.73 (t, J = 6.3 Hz, 2H, CH2), 1.48-1.39 (m, 4H, CH2),
1.35, 1.18, (d, 3JHH = 6.9 Hz, 12H, iPr CH3). 13C NMR (300 MHz,
C6D6): δ 175.43 (NdC), 162.85, 151.33, 141.55, 138.20, 134.54,
134.40, 132.34, 131.79, 129.36, 125.23, 125.04, 122.41, 121.16, (Ar),
100.62 (dC), 33.99, 27.69, 24.10, 23.57, (CH2), 28.54 (iPr CH),
25.78, 22.69, (iPr CH3). Anal. Calcd for C43H46NNiOP: C, 75.67;
H, 6.79; N, 2.05. Found: C, 75.73; H, 6.75; N, 2.08.
[(2,6-iPr2C6H3)NdCHC5H6O(C6H4)]Ni(CH3)(Py) (7c). Yield:
90%. 1H NMR (300 MHz, C6D6): δ 8.69 (m, 2H, o-H Py), 7.57
(m, 1H, Ar H), 7.20 (m, 2H, Ar H), 7.06-6.94 (m, 5H, Ar H,
NdCH), 6.53 (m, 1H, p-H Py), 6.16 (t, J = 6.6 Hz, m-H Py), 4.48
(sept, 3JHH = 6.9 Hz, 2H, iPr CH), 2.66 (m, 2H, CH2), 2.05 (m,
2H, CH2), 1.85 (m, 2H, CH2), 1.59, 1.24, (d, 3JHH = 6.9 Hz, 12H,
iPr CH3), -0.54 (s, 3H, NiCH3). 13C NMR (300 MHz, C6D6): δ
175.57 (NC), 162.11, 152.08, 142.56, 139.63, 135.71, 129.01,
128.86, 126.52, 125.97, 123.65, 123.26, (Ar, Py), 105.38 (dC),
33.75, 32.09, 28.32 (CH2), 28.65 (iPr CH), 25.28, 23.55, (iPr CH3),
-6.21 (Ni-CH3). Anal. Calcd for C29H34N2NiO: C, 72.16; H,
7.27; N, 5.61. Found: C, 72.18; H, 7.24; N, 5.65.
Ethylene Polymerization. A 200 mL autoclave was heated
under vacuum up to 130 °C for 10 h and then was cooled to the
desired reaction temperature in an oil bath with constant
temperature. The vessel was purged three times with ethylene
and then was charged with toluene (50 mL) under vacuum. A 10
or 20 μmol amount of cocatalyst dissolved in 10 mL of toluene
was added into the autoclave by syringe if necessary, followed by
the same amount of catalyst. The total volume of the reaction
medium was fixed at 100 mL. Then the reactor was sealed and
pressurized to the desired level, and the stirring motor was
engaged. Temperature control was maintained by internal cool-
ing water coils with temperature increases within 2 °C in every
case. After the prescribed reaction time, the stirring motor was
stopped, the reactor was vented, and the polymer was isolated
[(2,6-iPr2C6H3)NdCHC3H2O(C6H4)]Ni(Ph)(PPh3) (6a). Yield:
77%. 1H NMR (300 MHz, C6D6): δ 7.70-7.65 (m, 6H, Ar H),
7.50 (d, J = 7.2 Hz, 1H, NdCH), 7.13-6.77 (m, 18H, Ar H),
6.41-6.31 (m, 3H, Ar H), 4.24 (sept, 3JHH = 5.1 Hz, 2H, iPr CH),
3.27 (s, 2H, CH2), 1.36, 1.20, (d, 3JHH = 5.1 Hz, 12H, iPr CH3).
13C NMR (300 MHz, C6D6): δ 174.14 (NC), 158.33, 151.41,
146.90, 145.47, 141.99, 141.72, 138.04, 134.51, 134.38, 132.19,
131.62, 129.47, 126.47, 125.34, 124.76, 122.50, 121.21, (Ar),
106.82 (dC), 32.37 (CH2), 28.66 (iPr CH), 25.83, 22.82, (iPr
CH3). Anal. Calcd for C46H44NNiOP: C, 77.11; H, 6.19; N,
1.95. Found: C, 77.06; H, 6.22; N, 1.92.
[(2,6-iPr2C6H3)NdCHC4H4O(C6H4)]Ni(Ph)(PPh3) (6b). Yield:
65%. 1H NMR (300 MHz, C6D6): δ 7.69-7.63 (m, 6H, Ar H),
7.45 (d, J = 9.3 Hz, 1H, NdCH), 7.08-6.71 (m, 18H, Ar H),
6.41-6.32 (m, 3H, Ar H), 4.28 (sept, 3JHH = 6.9 Hz, 2H, iPr CH),
2.61 (t, J = 6.9 Hz, 2H, CH2), 2.43 (t, J = 6.9 Hz, 2H, CH2), 1.36,
3
i
1.25 (d, JHH = 6.9 Hz, 12H, Pr CH3). 13C NMR (300 MHz,
C6D6): δ 167.36 (NC), 162.11, 151.33, 146.95, 141.64, 137.90,
134.88, 134.53, 134.40, 132.18, 131.62, 131.32, 129.55, 129.10,
126.25, 125.90, 125.37, 125.15, 122.52, 121.24, (Ar), 101.58 (dC),
29.73, 26.78, (CH2), 28.70 (iPr CH), 25.83, 22.81, (iPr CH3). Anal.
Calcd for C47H46NNiOP: C, 77.27; H, 6.35; N, 1.92. Found: C,
77.31; H, 6.29; N, 1.95.
[(2,6-iPr2C6H3)NdCHC5H6O(C6H4)]Ni(Ph)(PPh3) (6c). Yield:
53%. 1H NMR (300 MHz, C6D6): δ 7.64-7.59 (m, 6H, Ar H),