Hydrodefluorination of Aliphatic C-H Bonds
A R T I C L E S
integration to judge the consumption of primary alkyl halides. The
Nonius Kappa Apex2 diffractometer, using graphite-monochro-
mated Mo KR radiation. All diffractometer manipulations, including
data collection, integration, scaling, and absorption corrections, were
carried out using the Bruker Apex2 software. Preliminary cell
constants were obtained from three sets of 12 frames. Data
collection was carried out at 120 K, using a frame time of 25 s and
a detector distance of 60 mm. The optimized strategy used for data
collection consisted of two phi and three omega scan sets, with
CH
the C
concentration was separately calibrated using mixtures of known
concentration of C CH and the requisite alkyl halides. In most
2
-Hal resonance was used for this purpose and integrated against
6
F
5
CH standard. The correspondence of integral values and
3
3
7
6
F
5
3
experiments, authentic samples of the main products of the reaction
were available. Where GC-MS was used to calculate the yields of
products, GC-MS integration was separately calibrated by using
mixtures of known concentrations of authentic samples of products
0.5° steps in phi or omega; completeness was 92.8%. A total of
2065 frames were collected. Final cell constants were obtained from
6 5 6 5
and of standards. The standards were typically C F H or C F Cl.
We estimate a range of 5-15% error in the determinations of yields/
conversions, depending on the particulars of the experiment.
Full experimental details on all reactions can be found in the
Supporting Information. Here, only representative examples are
provided. Reactions F8, F9, F10, F15, F16, and F18 have been
the xyz centroids of 5046 reflections after integration. The lower
than expected completeness arises from a faulty version of the
program COSMO, which generates run sets and strives to attain
sets with the highest combination of completeness and redun-
37
dancy. The predicted completeness was 99.7%, which was not
1
7
reported previously.
Reactions F2, F3, and F4. A J. Young tube was loaded with
Ph C[HCB11 Cl ] or Ph C[HCB11Cl11] or Ph C[HCB11 Br ] (5
µmol), C
p-FC CF
realized. Later versions produced satisfactory results with other
crystals, but additional crystals of this material were not available
at that time. Nonetheless, the data are quite satisfactory, and the
results of the structure analysis are unequivocal. The error led to a
CheckCIF Alert B error; accordingly, a validation reply form section
has been added to the CIF to explain the Alert B.
3
H
5
6
3
3
H
5
6
6
F
6
(15 µL, 0.13 mmol), o-dichlorobenzene (0.2 mL), and
(0.30 mL, 2.3 mmol) and cooled using a precooled
6
H
4
3
(
(
glovebox refrigerator set at -35 °C) copper shot bath. Then, Et
3
SiH
1.1 mL, 6.9 mmol) was added slowly, and the tube was allowed
19
From the lack of systematic absences, the observed metric
to stand for 1 h; then the tube was closed. The F NMR spectrum
of one of the reactions (F4) was checked after 1 h, to show
j
constants, and intensity statistics, space group P1 was chosen
initially; subsequent solution and refinement confirmed the cor-
formation of Et
which 50% Si-F conversion was calculated. After 72, 84, and 96 h
for F2, F3, and F4, respectively, all p-FC CF had been consumed
and p-FC CH (-121.1 ppm) was present in the spectrum. The
F NMR measured yield for p-FC CH vs the C standard
3
SiF (-178.1 ppm) and Et
2 2
SiF (-146.2 ppm), for
3
8
rectness of this choice. The structure was solved using SIR-92
and refined (full-matrix least-squares) using the Oxford University
H
6 4
3
39
Crystals for Windows program. All ordered non-hydrogen atoms
were refined using anisotropic displacement parameters; hydrogen
atoms were fixed at calculated geometric positions and allowed to
ride on the corresponding carbon atoms.
6
H
4
3
1
9
6
H
4
3
6 6
F
was 48% for F2, 13% for F3, and 34% for F4. In addition to
+
+
+
p-FC
and Et
6
H
4
CH
2
3
(m/z 110), Et
3
SiF m/z 134 (M), Et
4
Si m/z 144 (M),
+
2
SiF
(m/z 124), GC-MS analysis indicated formation of
Compound Et Si[HCB H Cl ] contained significant disorder,
3
11
5
6
the Friedel-Crafts products p-FC
6
H
4
CH
2
C
6
H
3
Cl
m/z 254 (M) in all of F2, F3, and F4 ( F NMR overlapping near
119.9 ppm)). GC-MS yields of the Friedel-Craft products
calculated vs Et SiF) were 36% (F2), 51% (F3), and 42% (F4).
Reaction Cl3. A 10 mL glass vial equipped with a stir bar was
charged with Ph C[HCB11 Cl ] (3 mg, 5 µmol), p-FC CCl
0.30 mL, 2.1 mmol), and hexanes (0.2 mL) and stirred for 1 min.
2
(two isomers,
which was resolved successfully. The two-component disorder was
described with a constraint that the occupancies of the major and
minor components sum to 1.0. The major component atoms were
refined by using anisotropic displacement parameters, and the minor
component atoms were refined by using isotropic displacement
parameters. The atoms C(5) and C(6) were disordered, with the
occupancy of the major component at 0.727(9). The final least-
+
19
-
(
3
3
H
5
6
6
H
4
3
(
3
Hex SiH (2.2 mL, 6.4 mmol) was then added, the vial was closed,
squares refinement converged to R
1
) 0.0398 (I > 2σ(I), 5550 data)
and the contents were stirred for 12 h. After this time, the mixture
2
and wR
2
) 0.0882 (F , 8140 data, 460 parameters).
was checked by 19F NMR spectroscopy, which showed that the
resonance at -112.1 ppm (p-FC
p-FC CH (-120.3 ppm) accounted for 33% yield, with various
other resonances, likely Friedel-Crafts products (-118.8, -119.1,
124.6, -125.5 ppm), accounting for 51%. GC-MS analysis also
6
H
4
CCl
3
) had disappeared.
Acknowledgment. We are grateful for the support of this
research by the Department of Energy, Office of Basic Energy
Sciences (DE-FG02-06ER15815), the Alfred P. Sloan Foundation,
and the Dreyfus Foundation. We also thank the National Science
Foundation for the partial support of this work through grant CHE-
6
H
4
3
-
+
detected p-FC
Reaction M2. A 10 mL glass vial equipped with a stir bar was
charged with Ph C[HCB11Cl11] (1.5 mg, 1.9 µmol), C CF (100
µL, 0.70 mmol), C CCl (115 µL, 0.70 mmol), C (20 µL, 0.17
6 4 3
H CH m/z 109 (M).
0521047 for the purchase of a new X-ray diffractometer. We thank
3
6
F
5
3
Dr. Sara Kunz and Prof. Alfred Redfield for invaluable assistance
with NMR experiments and Albemarle Corp. for a gift of
Ph C[B(C F ) ]. We are grateful to the Brandeis University mass-
3 6 5 4
spectrometry center (BUMS) for assistance with MS characteriza-
tion of carborane anions.
F
6 5
3
6 6
F
mmol), and hexanes (0.8 mL), closed, and stirred for 2 min. An
aliquot of the mixture was taken and transferred into an NMR tube,
and the 19F NMR spectrum was recorded. Then, 3.1 equiv of
Hex
3
SiH (780 µL, 2.18 mmol) was added, and the contents were
stirred continuously. An aliquot of the reaction mixture was taken
after 8 min into an NMR tube, NBu
4
[BH
4
] was added to quench
Supporting Information Available: Experimental details and
characterization data. This material is available free of charge
via the Internet at http://pubs.acs.org.
the reaction, and the 19F NMR spectrum was recorded. Similarly,
an aliquot of the reaction mixture was taken at 15 and 20 min into
4 4
[BH
], and the 19F NMR spectra were
NMR tubes with NBu
recorded. The NMR spectrum recorded at the end of 20 min
revealed 97% of C CF and only 2% of C CCl remaining.
The resonances at -146.7, -162.1, and -165.6 ppm corresponded
to C CH
X-ray Data Collection, Solution, and Refinement for
Si[HCB11 Cl ]. A suitable crystal was obtained by cooling a
solution of Et Si[HCB11 Cl ] in a mixture of fluorobenzene and
hexanes to -35 °C. All operations were performed on a Bruker-
JA100605M
6
F
5
3
6
F
5
3
6
F
5
3
.
(37) Apex2, Version 2 User Manual; M86-E01078, Bruker Analytical X-ray
Systems: Madison, WI, June 2006.
(
38) Altomare, A; Cascarano, G; Giacovazzo, G.; Guagliardi, A.; Burla,
M. C.; Polidori, G.; Camalli, M. J. Appl. Crystallogr. 1994, 27, 435.
39) Betteridge, P. W.; Carruthers, J. R.; Cooper, R. I.; Prout, K.; Watkin,
D. J. J. Appl. Crystallogr. 2003, 36, 1487.
Et
3
H
3
5
6
H
5
6
(
J. AM. CHEM. SOC. 9 VOL. 132, NO. 13, 2010 4953