Article
Organometallics, Vol. 30, No. 3, 2011 455
NMR was done under similar conditions in C6D6 in an NMR
tube equipped with a Teflon valve.
δ -135.8 (m, 2F, F1 and F4), -171.3 (m, 2F, F2 and F3). 31P{1H}
NMR (C6D6, 121.5 MHz, 298 K): δ 19.2 (br, W1/2=140 Hz). 19
F
An alternate synthesis was performed in neat isobutene at
room temperature. A solution of (PEt3)2NiMe2 (1.0 g, 3.08
mmol) was dissolved in 10 mL of isobutene. After 2 weeks the
solution was slowly evaporated at -35 °C to provide a thermally
sensitive yellow oil that was identified as (PEt3)2Ni(η2-H2Cd
NMR (pentane, 282.4 MHz, 163 K): δ -132.8 (m, 1F, F1 or
F4), -141.5 (m, 2F, F1 or F4) δ -158.2 (m, 1F, F3), -189.2 (m,
1F, F2). 31P{1H} NMR (pentane, 121.5 MHz, 163 K): δ 12.6,
16.3, 21.3, and 25.3 (m). Anal. Calcd for C30H62F4Ni2P4 (mol wt
740.09): C, 48.69; H, 8.44. Found: C, 48.91; H, 8.69.
Characterization of (PEt3)2Ni(η2-1,2,3,4-C6F4H2) (7). Com-
plex 7 was prepared in equilibrium amounts by the addition of
1,2,3,4-C6F4H2 to 6 in toluene-d8 and characterized by variable-
temperature 1H, 31P{1H}, and 19F NMR spectroscopy. 1H
NMR (d8-toluene, 300 MHz, 298 K, aromatic resonance): δ 5.27
(br, 2H, W1/2=120 Hz, C6F4H2, peak associated with free 1,2,3,
4-C6F4H2 is also broad). 19F (toluene-d8, 282.4 MHz, 298 K):
δ -128.9 (br apparent d, 2F, W1/2 =60 Hz), -173.2 (br, 2F,
CMe2) by H, 31P{1H}, and 13C{1H} NMR spectroscopy. H
NMR (C6D6, 300 MHz, 298 K): 0.96 (overlapping m, 18H total,
PCH2CH3), 1.43 (overlapping m, 12H total, PCH2CH3), 1.67 (d,
6H, J = 7.3 Hz, CdCMe2), 1.78 (m, 2H, CdCH2). 31P{1H}
NMR (C6D6, 121.5 MHz, 298 K): δ 16.0 and 17.2 (AB doublets,
2JPP=53 Hz). 13C{1H} NMR (C6D6, 75.4 MHz, 298 K): δ 8.77
(s, PCH2CH3), 9.02 (s, PCH2CH3), 19.0 (dd, JPC=16.4, 4.0 Hz,
PCH2), 19.5 (dd, JPC=15.0, 3.0 Hz, PCH2), 27.7 (d, JPC=4.0 Hz,
CdCMe2), 46.7 (dd, JPC = 18.0, 4.0 Hz, C=CH2), 56.0 (dd,
JPC=24, 4 Hz, Me2CdC).
1
1
W
1/2=70 Hz), 31P{1H} NMR (toluene-d8, 121.5 MHz, 298 K): δ
16.3 (br, W1/2=70 Hz). 1H NMR (toluene-d8, 300 MHz, 253 K,
aromatic resonance): δ 5.27 (apparent t, J=6.5 Hz, 2H). 19F
NMR (toluene-d8, 282.4 MHz, 213 K): δ -127.7 (br, second-
order multiplet), -174.5 (sharp second-order multiplet, 2F).
31P{1H} NMR (toluene-d8, 121.5 MHz, 213 K): δ 16.5 (sharp t,
Synthesis of [(PEt3)2Ni]2(μ-η2:η2-1,2,4,5-C6F4H2) (3). To a
pentane solution of 2 generated from 1 (1.0 g, 3.08 mmol) was
added 1,2,4,5-tetrafluorobenzene (1.0 g, 6.66 mmol, 2.2 equiv).
The solution was heated to the boiling point of pentane with
rapid stirring for 1.5 h; the progress of the reaction was
monitored by 31P{1H} NMR using aliquots of the solution.
The solution was then dried, and the remaining solid was
recrystallized from pentane, which provided the product as
yellow crystals (0.30 g, 13%) of sufficient quality for structure
J
FP=23.3 Hz).
Characterization of [(PEt3)2Ni]2(μ-η2:η2-1,2,3,5-C6F4H2) (9).
To a solution of 2 in hexamethyldisiloxane generated from 1
(1.0 g, 3.08 mmol) was added 1,2,3,5-tetrafluorobenzene (0.5 g,
3.3 mmol, 1.1 equiv). The mixture was placed under reduced
pressure and rapidly stirred. The vacuum was stopped occa-
sionally to allow the solution to remain near room temperature.
This procedure was continued for 30 min. An aliquot was
analyzed by NMR spectroscopy, and 9 was found to be the
major fluorine-containing product, but it could not be isolated
1
determination by X-ray diffraction. H NMR (toluene-d8, 300
MHz, 298 K): δ 1.05 (m, 36H, PCH2CH3), 1.64 (br, 24H, PC-
H2CH3), 3.02 (m, 2H, C6F4H2). 19F NMR (C6D6, 282.4 MHz,
298 K): δ -136.0 (m, 2F, F1 and F2), -146.7 (br m, 2F, F4 and
F5). 31P{1H} NMR (toluene-d8, 121.5 MHz, 298 K): δ 19.0 (br,
W1/2=325 Hz). 31P{1H} NMR (toluene-d8, 121.5 MHz, 233 K):
1
by recrystallization. H NMR (toluene-d8, 300 MHz, 293 K,
arene resonances): δ 3.8 (br, 2H, W1/2=70 Hz C6F4H2). 19F{1H}
NMR (toluene-d8, 282.4 MHz, 293 K): δ -113.7 (m, F5), -137
(br, W1/2=1500 Hz, F3), -162.2 (m, F2), -176 (br, W1/2=1500 Hz,
F1). 31P{1H} NMR (toluene-d8, 121.5 MHz, 298 K): δ 19.0 (br,
W1/2=130 Hz). 1H NMR (toluene-d8, 300 MHz, 233 K, arene
resonances): δ 2.75 (dm, J=23 Hz, 1H, C6F4H2), 4.81 (dm, J =
11.5 Hz, 1H, C6F4H2). 19F{1H} NMR (pentane, 282.4 MHz, 193
K): δ -113.7 (br m, 1F, F5), -137.1 (br m, apparent 36 Hz
quartet, F3), -162.2 (br m, F2), -175.7 (br m, apparent 36 Hz
quartet, F1). 31P{1H} NMR (pentane, 121.5 MHz, 193 K): δ 13.4
(br dddd, J=8,26,38 and 82 Hz), 15.6 (br m), 21.1 (br ddd J=5,
36, and 42 Hz), 25.8 (br ddd, J=8, 29, and 40 Hz).
2
2
δ 15.0 (m, JPP=42 Hz, d of apparent t, JPP=42 Hz, JPF
=
27 Hz, 2P), 22.8 (m, 2JPP=42 Hz, 2P). Anal. Calcd for C30H62-
F4Ni2P4 (mol wt 740.09): C, 48.69; H, 8.44. Found: C, 48.90; H,
8.73.
Characterization of (PEt3)2Ni(η2-1,2,4,5-C6F4H2) (4). Com-
plex 4 was prepared in equilibrium amounts by the addition of
1,2,4,5-C6F4H2 to 3 in toluene-d8 and characterized by variable-
temperature 1H, 31P{1H}, and 19F NMR spectroscopy. 1H
NMR (toluene-d8, 300 MHz, 298 K, select resonances): δ 4.87
(virtual pentet, J=9.0 Hz, 2H, C6F4H2). 19F{1H} (toluene-d8,
282.4 MHz, 298 K): δ -143.4 (m, 4F). 31P{1H} NMR (toluene-
1
d8, 121.5 MHz, 298 K): δ 17.5 (br). H NMR (toluene-d8, 300
MHz, 183 K, select resonances): δ 3.9 and 5.8 (br, C6F4H2).
Characterization of (PEt3)2Ni(η2-1,2,3,5-C6F4H2) (10). Com-
plex 10 was prepared in equilibrium amounts by the addition of
1,2,3,5-C6F4H2 to a solution of 9 in toluene-d8 and characterized
31P{1H} NMR (toluene-d8, 121.5 MHz, 263 K): δ 17.5 (pentet,
JPF=12.5 Hz).
Characterization of (PEt3)2NiH-2,3,5,6-F4C6H (5). Complex
1
by variable-temperature H, 31P{1H}, and 19F NMR spectros-
5 was prepared in equilibrium amounts by the addition of 1,2,
4,5-C6F4H2 to 4 in toluene-d8 and characterized by variable-
temperature 1H, 31P, 31P{1H}, and 19F NMR spectroscopy.
1H NMR (toluene-d8, 300 MHz, 233 K, selected resonances):
δ-14.30 (ttt, JPH = 67.7 Hz, JFH = 9.5 Hz, JFH = 4.2 Hz,
Ni-H), 6.48 (m, Ar-H). 19F{1H} NMR (toluene-d8, 282.4
MHz, 298 K, complex 2 only): δ -117.8 (AA0MM0 multiplet,
o-F), -143.7 (AA0MM0 multiplet, m-F). 31P{1H} NMR
(toluene-d8, 121.5 MHz, 233 K): δ 23.5 (s). 31P NMR (C7D8,
121.5 MHz, 233 K): δ 23.5 (br d, 2JPH=68 Hz).
copy. 1H NMR (d8-toluene, 300 MHz, 253 K, aromatic resonance):
δ 4.90 (m, 2H). 19F{1H} NMR (d8-toluene, 282.4 MHz, 298 K):
δ -106.0 (br m, 1F, F5), -149.9 (br m, 2F, F1 and F3), -161.5
(br m, 1F, F2). 31P{1H} NMR (toluene-d8, 121.5 MHz, 298 K): δ
15 (br, W1/2=600 Hz). 1H NMR (d8-toluene, 300 MHz, 185 K,
aromatic resonance): δ 4.9 (br, W1/2=100 Hz, 2H). 19F NMR
(toluene-d8, 282.4 MHz, 173 K): δ -106.0 (br m, 1F, F5), -143
(br m, 1F, F1 or F3), -146 (br m, 1F, F1 or F3), -161.5 (br m,
F2). 31P{1H} NMR (toluene-d8, 121.5 MHz, 213 K): δ 15.4 and
20.9 (m).
2
4
5
Synthesis of [(PEt3)2Ni]2(μ-η2:η2-1,2,3,4-C6F4H2) (6). To a
pentane solution of 2 generated from 1 (1.0 g, 3.08 mmol) was
added 1,2,3,4-tetrafluorobenzene (1.0 g, 6.6 mmol, 2.1 equiv).
The solution was heated to the boiling point of pentane with
rapid stirring for 1 h; the progress of the reaction was monitored
by 31P{1H} NMR using aliquots of the solution. The solution
was then dried, and the remaining solid was recrystallized from
hexamethyldisiloxane, which provided the product as yellow
crystals (0.23 g, 10%) of sufficient quality for structure deter-
mination by X-ray diffraction. 1H NMR (C6D6, 300 MHz, 298
K): δ 1.01 (m, 36H, PCH2CH3), 1.60 (br, 24H, PCH2CH3), 3.62
(m, 1H, C6F4H2). 19F NMR (C6D6, 282.4 MHz, 298 K):
Characterization of (PEt3)2NiH-2,3,4,6-F4C6H (11). Complex
11 was prepared in equilibrium amounts by the addition of
1,2,3,5-C6F4H2 to a solution of 9 in toluene-d8 and characterized
by variable-temperature 1H, 31P, 31P{1H}, and 19F NMR spec-
troscopy. 1H NMR (hydride region) (toluene-d8, 300 MHz,
2
223 K): δ -14.56 (t, JPH = 69 Hz, Ni-H). 19F{1H} NMR
(toluene-d8, 282.4 MHz, 293 K): δ -90.5 (dd, JFF=13.7, 2.8 Hz,
F6), -110.0 (dt, JFF=33.3 Hz, JPF=2.8 Hz, F2), -144.6 (dd,
JFF=19.0, 2.8 Hz, F4),-170.2 (ddd, JFF=33.3, 19.0, and 13.7
Hz, F3). 19F NMR (toluene-d8, 282.4 MHz, 293 K): δ -90.5
(dddd, JFF=13.7, 2.8 Hz, JFH=7.8, 4.5 Hz, F6), -110.0 (dddt,
J
FF=33.3 Hz, JFH=10.0, 2.5 Hz, JPF=2.8 Hz, F2), -144.6 (ddd,