Trifluoromethylation Reactions at Nickel
Organometallics, Vol. 27, No. 15, 2008 3937
Table 2. Effect of Additives on the Thermolysis of 11
Table 3. Crystal Data and Structure Refinement Parameters for 13,
15, and 16
13
15
16
chem formula
formula wt
cryst dimens (mm)
C
25H39F3NiP2
C
16H32F6NiP2
C
16H38NiP2
517.21
0.36 × 0.16 ×
459.07
351.11
0.30 × 0.20 ×
0.24 × 0.13 ×
0.12
0.10
0.13
color, habit
cryst syst
yellow, block
triclinic
yellow, block
monoclinic
0.710 70
1.143
yellow, block
monoclinic
0.710 70
1.163
wavelength (Å)
0.710 70
0.923
abs coeff (mm-1
space group, Z
a (Å)
)
entry additive (amt (equiv))
conditions
yield of PhCF3 (%)a
j
P1, 2
C2/c, 4
C2/c, 4
8.5134(12)
11.8936(17)
13.4820(19)
105.110(2)
94.789(2)
102.992(2)
1269.5(3)
1.353
14.267(4)
8.586(2)
17.109(4)
90
99.819(4)
90
2065.1(9)
1.477
-100
0.0491, 0.1258
0.0599, 0.1296
1.104
2.42-32.03
17421
12.837(7)
8.514(5)
17.740(10)
90
96.954(11)
90
1924.7(19)
1.212
-173
0.0448, 0.0807
0.0704, 0.0875
1.084
3-27.48
6433
1
2
3
4
5
6
Fe(bpy)3(PF6)3 (1)
(NH4)2Ce(NO3)6 (5)
Ph-Br (95)
PhZnBr (25)
ZnBr2 (5)
THF, 25 °C, 3 days
THF, 25 °C, 3 days
THF, 25 °C, 3 days
THF, 25 °C, 3 days
THF, 25 °C, 14 h
toluene, 80 °C, 5 h
0
0
0
11
19
22
b (Å)
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
H2O (100)
Fcalcd (Mg/m3)
temp (K)
a Yields
determined
by
19F
NMR
relative
to
100
2-fluoro-1,3-dimethylbenzene as an internal standard.
R indices (I >2σ(I))
R indices (all data)
goodness of fit
θ range (deg)
no. of data collected
no. of unique data
Rint
0.0331, 0.0763
0.0457, 0.0821
1.037
1.83-32.03
22471
8722
0.0242
co-workers with a Pd-CF3 complex.40 A green solid had also
precipitated in the reaction with water, which we attribute to
Ni(OH)2. Although attempts to further optimize the cross-
coupling reactions in entries 4-6 were fruitless, the data do
suggest that trifluoromethylations are indeed possible at nickel,
even at room temperature. Ligands of other geometries and
hapticities may better coax a reductive elimination of Ar-CF3
at nickel, and these will be a focus of further study.
3580
0.0386
2193
0.0510
(dippe)Ni(3-Me-Ph)Br (8). Yield: 74%. 1H NMR (C6D6):
δ 7.79 (d, J ) 5.1 Hz, 1H), 7.71 (t, J ) 6.3 Hz, 1H), 7.24 (t, J )
7.2, 1H), 6.91 (d, J ) 7.2 Hz, 1H), 2.41 (s, 3H), 2.30 (m, 2H),
1.92 (m, 2H), 1.6-0.86 (m, 28 H). 31P NMR (CDCl3): δ 74.79 (d,
J ) 20.11 Hz), 69.75 (d, J ) 20.11 Hz). Anal. Calcd (found) for
C21H39BrNiP2: C, 51.26 (51.10); H, 7.99 (8.07).
Experimental Section
General Considerations. All manipulations were performed
using standard Schlenk and high-vacuum techniques41 or in a
nitrogen-filled drybox, unless otherwise noted. Solvents were
distilled from Na/benzophenone or CaH2. All reagents were used
as received from commercial vendors, unless otherwise noted.
Aluminum oxide (activated, neutral, Brockmann I, ∼150 mesh) was
dried at 200 °C under vacuum for 2 days prior to use. Elemental
analyses were performed by Desert Analytics. 1H NMR spectra
were recorded at ambient temperature (unless otherwise noted) on
a Varian Oxford 300 MHz spectrometer and referenced to residual
proton solvent peaks. 31P spectra were recorded on the Varian
Oxford spectrometer operating at 121 MHz and referenced to an
85% phosphoric acid external standard set to 0 ppm. 19F spectra
were recorded on the Varian Oxford spectrometer operating at 282
MHz and were referenced to CFCl3 set to zero. A Rigaku SCXMini
diffractometer (University of Hawaii) and a Bruker SMART APEX
II CCD Platform diffractometer (University of Rochester) were used
for X-ray structure determinations. Table 3 gives crystal data and
structure refinement parameters for 13, 15, and 16.
(dippe)Ni(naphthyl)Br (9). Yield: 83%. 1H NMR (DMSO-d6):
δ 7.76 (m, 2H), 7.64 (t, J ) 8.9 Hz, 2H), 7.45 (d, J ) 8.4, 1H),
7.32 (t, J ) 7.8 Hz, 1H), 7.23 (t, J ) 7.8 Hz, 1H), 2.27 (m, 2H),
1.90 (m, 2H), 1.6-1.13 (m, 28H). 31P NMR (DMSO-d6): δ 76.9
(m), 73.3 (d, J ) 19.9 Hz). Anal. Calcd (found) for C24H39BrNiP2:
C, 54.58 (53.15); H, 7.44 (7.27).
(dippe)Ni(4-OMe-Ph)Br (10). Yield: 80%. 1H NMR (CD2Cl2):
δ 7.29 (t, J ) 7.1 Hz, 2H), 6.64 (d, J ) 7.5 Hz, 2H), 3.69 (s, 3H),
2.36 (m, 2H), 2.14 (m, 2H), 1.8-1.03 (m, 28H). 31P NMR
(CD2Cl2): δ 76.3 (d, J ) 19.9 Hz), 70.6 (d, J ) 20.1 Hz). Anal.
Calcd (found) for C21H39BrNiOP2: C, 49.64 (50.15); H, 7.74 (7.47).
General Procedure To Prepare the (dippe)Ni(Ar)(CF3)
Complexes 11-14. A 50 mL round-bottom flask (RBF) was
charged with the corresponding (dippe)Ni(Ar)(Br) (7-10; 1 mmol),
CsF (304 mg, 2 mmol), CF3Si(CH3)3 (0.296 mL, 2 mmol), and
THF (25 mL). The reaction mixture was stirred for 14 h at room
temperature under a nitrogen atmosphere. The reactions were
monitored by taking aliquots and measuring the 31P NMR and 19
F
General Procedure To Prepare the (dippe)Ni(Ar)Br
Complexes 7-10. A 100 mL round-bottom flask (RBF) was
charged with Ni(COD)2 (1.375 g, 5 mmol), dippe (1.52 mL, 5
mmol), and toluene (50 mL). The dark brown solution was stirred
for 10 min at room temperature, and then 5 mmol of corresponding
ArBr was added. The resulting solution was stirred at 50 °C for 3
days under a nitrogen atmosphere, at which time a yellow precipitate
was observed. The resulting suspension was reduced in volume on
a high-vacuum line, and the solids were filtered, washed with
toluene and pentane, and dried under vacuum.
spectra. When all starting material had been consumed, the reaction
mixture was filtered through a 1 cm pad of alumina, and the filtrate
was concentrated under high vacuum. The solids were washed with
toluene and pentane and dried under vacuum.
(dippe)Ni(Ph)(CF3) (11). Yield: 57%. 1H NMR (THF-d8): δ 7.47
(m, 2H), 7.2-6.9 (m, 3H), 2.30 (m, 1H), 2.08 (m, 2H), 1.83 (m,
2H), 1.06-0.96 (m, 27H). 31P NMR (THF-d8): δ 75.75 (m), 63.97
(dq, J ) 35.6, 9.1 Hz). 19F NMR (THF-d8): δ -19.97 (dd, J )
34.6, 15.3). Anal. Calcd (found) for C21H37F3NiP2: C, 53.99 (54.50);
H, 7.98 (7.69).
1
(dippe)Ni(Ph)Br (7). Yield: 65%. H NMR (CD2Cl2): δ 7.85
(dippe)Ni(3-Me-Ph)(CF3) (12). Yield: 54%. 1H NMR (CD2Cl2):
δ 8.0 (d, J ) 6.2 Hz, 1H), 7.85 (t, J ) 6.3 Hz, 1H), 7.54 (t, J )
7.2, 1H), 7.02 (d, J ) 7.2 Hz, 1H), 2.5 (s, 3H), 2.30 (m, 2H), 1.92
(m, 2H), 1.6-0.9 (m, 28 H). 31P NMR (CD2Cl2): δ 75.53 (m),
63.97 (dq, J ) 37, 10.9 Hz). 19F NMR (CD2Cl2): δ -16.54 (dd, J
) 37, 15.5 Hz). Anal. Calcd (found) for C22H39F3NiP2: C, 54.91
(54.62); H, 8.17 (7.90).
(t, J ) 6.3 Hz, 2H), 6.93 (t, J ) 6.3, 2H), 6.75 (t, J ) 6.3 Hz, 1H),
2.35 (m, 2H), 2.15 (m, 2H), 1.81-1.01 (m, 28H). 31P NMR
(CD2Cl2): δ 76.91 (d, J ) 20.6 Hz), 71.23 (d, J ) 20.6 Hz). Anal.
Calcd (found) for C20H37BrNiP2: C, 50.25 (50.54); H, 7.80 (7.95).
(40) Grushin, V. V.; Marshall, W. J. J. Am. Chem. Soc. 2006, 128, 4632–
4641.
(41) Vicic, D. A.; Jones, G. D. In ComprehensiVe Organometallic
Chemistry III; Crabtree, R. H., Mingos, D. M. P., Eds.; Elsevier: Amsterdam,
2006; Vol. 1.
1
(dippe)Ni(naphthyl)(CF3) (13). Yield: 70%. H NMR (C6D6):
δ 8.21-7.2 (m, 7H), 2.16 (m, 2H), 1.78 (m, 2H), 1.5-0.5 (m, 28H).