benzophenone ketal; diethyl ether, d8-toluene, d6-benzene,
iso-octane, pentane, benzene, C6D6, bromobenzene, and d5-
bromobenzene were dried and stored over sodium/benzophenone
ketal in glass bombs under vacuum. Methylene chloride and d2-
methylene chloride were pre-dried and stored over calcium hy-
(m, 2F, N-o-C6F4), -163.7 (tm, JFF = 21.5 Hz, 4F, N-m-C6F5),
-164.7 (tm, JFF = 21.4 Hz, 2F, N-p-C6F5). N-pentafluorophenyl-
3,4,5,6-tetrafluorophenylene-1,2-diamine: 1H NMR (CDCl3): d
4.93 (br s, 1H, NH), 4.12 (br s, 2H, NH2). 19F NMR (CDCl3):
d -150.1 (dd, JFF = 22.1 Hz, 7.9 Hz, 1F, NH-o-C6F4), -158.2
(dm, JFF = 20.5 Hz, 2F, NH-m-C6F5), -159.4 (t, JFF = 21.3 Hz,
1F, NH-p-C6F5), -161.8 (dt, JFF = 21.2 Hz, 7.6 Hz, 1F, NH2-o-
C6F4), -163.2 (td, JFF = 21.6 Hz, 4.5 Hz, 2F, NH-o-C6F5), -166.9
1
dride. Nuclear magnetic resonance spectroscopy (1H, 19F, 13C{ H},
1
31P{ H}, 27Al, 19F–19F COSY, 1H–19F decoupling experiments) was
performed on a Bruker AMX 300 (1H – 300.138 MHz, 19F –
282.371 MHz, 27Al – 78.171 MHz), Bruker DMX 300 (1H –
300.138 MHz, 13C – 75.465 MHz, 31P – 121.507 MHz), or Bruker
Avance DRX 400 (1H – 400.134 MHz, 19F – 376.448 MHz,
31P – 161.710 MHz) spectrometer. 13C NMR resonances are not
reported for carbon atoms bonded directly to fluorine atoms.
Microanalyses were performed using a Perkin Elmer Model 2400
Series II Elemental Analyzer. EPR experiments were performed
on a Bruker EMX10/12 with VT accessory and gaussmeter.
The compounds 3,4,5,6-tetrafluorophenylene-1,2-diamine22,44
(tt, JFF = 21.6 Hz, 4.4 Hz, 1F, NH2-m-C6F4), -173.3 (td, JFF
21.8 Hz, 6.1 Hz, 1F, NH-m-C6F4).
=
Synthesis of 2. A toluene (15 mL) solution containing 1
(216 mg, 0.422 mmol) and AlMe3 (2.0 M in toluene, 0.21 mL,
0.42 mmol) was heated at 110 ◦C for 2 h. During this time, bubbles
were observed, indicating the evolution of CH4. The solution was
cooled to room temperature and the solvent removed in vacuo
to give an off-white solid which was identified as 2 (144 mg,
1
0.130 mmol, 61.9% based on Al). H NMR (THF-d8): d -0.62
33
and Cp*(t-Bu3P N)TiMe2 were prepared according to liter-
(s, 6H, AlMe). 19F NMR (THF-d8): d -152.4 (d, JFF = 21.3 Hz, 8F,
N-o-C6F5), -162.0 (dd, JFF = 15.3 Hz, 10.2 Hz, 4F, N-m-C6F4),
ature procedures or slight variations thereof. The compound
PhNHMe2Cl was prepared by reaction of PhNMe2 with one
equivalent of ethereal HCl, the solvent was removed in vacuo,
and the precipitate was recrystallized from Et2O prior to use.
Hexafluorobenzene (C6F6) was purchased from Aldrich Chemicals
and dried twice over P2O5 under an inert atmosphere before being
vacuum transferred to a sealed bomb for storage. Trityl chloride
(Ph3CCl) was purchased from Aldrich Chemicals and sublimed
prior to use. Pentafluoronitrobenzene was purchased from Aldrich
Chemicals and used as received. All other reagents were purchased
from Aldrich Chemicals and, where appropriate, purified using
standard techniques.45
-166.8 (tm, JFF = 21.3 Hz, 8F, N-m-C6F5), -168.5 (tm, JFF
=
21.4 Hz, 4F, N-p-C6F5), -174.6 (dd, JFF = 15.0 Hz, 10.1 Hz, 4F,
N-m-C6F4).
Synthesis of 3-H. A toluene (15 mL) solution containing 1
(438 mg, 0.855 mmol) and AlMe3 (2.0 M in toluene, 0.21 mL,
◦
0.42 mmol) was heated at 110 C for 2 h, during which time the
colour of the solution changed from colourless to purple. During
this time, bubbles were observed, indicating the evolution of CH4.
The solution was cooled to room temperature and the solvent
removed in vacuo to give a purple solid, which was dissolved in
pentane and recrystallized at -35 ◦C. The resulting purple crystals
Synthesis of 1.
A
THF (40 mL) solution of 3,4,5,6-
were isolated and identified as 3 (229 mg, 0.218 mmol, 53.2%). 19
F
tetraflu◦orophenylene-1,2-diamine (439 mg, 2.44 mmol) was cooled
to -78 C under an argon atmosphere. A hexanes solution of n-
butyl lithium (1.6 M, 3.1 mL, 5.0 mmol) was added slowly to the
THF solution, and the stirring solution turned from colourless
to a bright canary yellow. The reaction was stirred for 20 min
NMR (C6D6): d -152.5 (m, 4F, N-m-C6F4), -154.7 (m, 8F, N-o-
C6F5), -161.9 (m, 4F, N-o-C6F4), -163.1 (ov m, 12F, N-m-C6F5,
N-p-C6F5).
Synthesis of 3-Li. Compound 1 (510 mg, 0.996 mmol) and
LiAlH4 (17 mg, 0.45 mmol) were weighed into a 50 mL round-
bottomed flask and connected to a swivel frit under an inert
atmosphere. Toluene (25 mL) was condensed onto the solids at
-78 ◦C and the resulting suspension was allowed to warm to room
temperature. The reaction flask was heated at 80 ◦C overnight
under argon, after which time a copious amount of suspended
white solid was present. The reaction mixture was cooled to room
temperature and filtered. The white solid was washed several times
with toluene to remove excess 1 and was dried in vacuo to afford
3-Li as a white powder (387 mg, 0.367 mmol, 81.0%). Single
crystals of 3-Li·(THF)2 were grown by layering hexanes onto a
◦
at -78 C, whereupon an excess of hexafluorobenzene (1.40 mL,
2.27 g, 12.2 mmol) was added dropwise to the solution turning
the reaction a deep red colour. The temperature of the solution
was raised to -5 ◦C and stirred overnight under argon. The
reaction was quenched with water (20 mL), and the resulting
mixture diluted with brine and dichloromethane (200 mL ea.).
The two layers were mixed thoroughly and the organic layer was
isolated, and the aqueous layer was re-extracted with 2 ¥ 200 mL
dichloromethane. The organic fractions were combined, dried over
magnesium sulfate, filtered, and the solvent was removed in vacuo
to give a dark red oily solid. Separation by column chromatogra-
phy on silica gel using 5–20% ethyl acetate in hexanes as the eluant
gave unreacted 3,4,5,6-tetrafluorophenylene-1,2-diamine (88 mg,
0.490 mmol, 20.1%), the by-product N-pentafluorophenyl-3,4,5,6-
tetrafluorophenylene-1,2-diamine (185 mg, 0.534 mmol, 21.9%),
and the target compound N,N¢-bis-pentafluorophenyl-3,4,5,6-
tetrafluorophenylene-1,2-diamine (1) as a pale pink powder. Re-
crystallization from hot hexanes gave diamine 1 as a white fibrous
solid (500 mg, 0.976 mmol, 40.0%). Anal. Cald. for C18H2F14N2: C,
42.21; H, 0.39; N, 5.47. Found: C, 42.38; H, 0.70; N, 5.58. 1H NMR
(CD2Cl2): d 5.47 (br s, 2H, NHC6F5). 19F NMR (CD2Cl2): d -152.4
(m, 2F, N-m-C6F4), -155.3 (d, JFF = 20.6 Hz, 4F, N-o-C6F5), -162.6
◦
THF solution of 3-Li and storing the solution at -35 C. Anal.
Calcd. for C36AlF28LiN4: C, 41.01; H, 0.00; N, 5.31. Found: C,
41.69; H, 0.64; N, 5.36. 19F NMR (CD2Cl2): d -151.1 (br, 8F,
N-o-C6F5), -164.4 (dd, JFF = 16.1 Hz, 11.2 Hz, 4F, N-m-C6F4),
-166.6 (ov, 12F, N-m-C6F5, N-p-C6F5), -176.1 (dd, JFF = 16.0 Hz,
11.2 Hz, 4F, N-o-C6F4).
Synthesis of 3-Ph3C. Compound 3-Li (720 mg, 0.683 mmol)
was weighed into a 2-neck 25 mL round-bottomed flask under
an inert atmosphere. A solid addition tube containing Ph3CCl
(200 mg, 0.717 mmol) connected to the flask and the apparatus was
attached to a swivel frit. Dichloromethane (15 mL) was condensed
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 10256–10263 | 10261
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