Catalytic C-F bond hydrogenolysis of fluoroaromatics by [(η5-C5Me5)RhI(2,2′-bipyridine)]

Article abstract of DOI:10.1021/om500647h

A new class of efficient catalyst, the Rh(I) complex [(η⁵-C₅Me₅)Rh^I(bpy)] (1; bpy = 2,2′-bipyridine), for the C-F bond hydrogenolysis of fluoroaromatics (C₆F₅CF₃, C₆F₆, C₆F₅H, and C₆F₅CH₃) is presented. The best turnover number of 380 for C₆F₆ is afforded by using 0.1 mol % of 1, 0.8 MPa of H₂, and 2 equiv of Et₂NH in CH₃CN at 25 °C. The successful isolation of the C-F bond cleavage product [(η⁵-C₅Me₅)Rh^III(bpy)(C₆F₅)](F) as a plausible intermediate of the catalytic hydrogenolysis of C₆F₆ by 1 is also described.

Full text of DOI:10.1021/om500647h

Communication
pubs.acs.org/Organometallics
Catalytic C−F Bond Hydrogenolysis of Fluoroaromatics by
5
I
[
(η ‑C Me )Rh (2,2′-bipyridine)]
5
5
Hidetaka Nakai,* Kihun Jeong, Takahiro Matsumoto, and Seiji Ogo*,†,‡
,† †
†,‡
†
‡
Department of Chemistry and Biochemistry, Graduate School of Engineering, and International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
*
S Supporting Information
ABSTRACT: A new class of efficient catalyst, the Rh(I) complex
5
I
[
(η -C Me )Rh (bpy)] (1; bpy = 2,2′-bipyridine), for the C−F bond
5
5
hydrogenolysis of fluoroaromatics (C F CF , C F , C F H, and
6
5
3
6
6
6 5
C F CH ) is presented. The best turnover number of 380 for C F is
6
5
3
6 6
afforded by using 0.1 mol % of 1, 0.8 MPa of H , and 2 equiv of
2
Et NH in CH CN at 25 °C. The successful isolation of the C−F
2
3
5
III
bond cleavage product [(η -C Me )Rh (bpy)(C F )](F) as a
5
5
6 5
plausible intermediate of the catalytic hydrogenolysis of C F by 1
6
6
is also described.
5
III
atalytic activation and transformation of the C−F bonds
product [(η -C Me )Rh (bpy)(C F )](F) (2(F)) as a plau-
5 5 6 5
C
under mild conditions are a challenge in synthetic
sible intermediate of the catalytic hydrogenolysis of C F by 1.
The Rh(I) complex 1 was prepared by a modified literature
method via reduction of the Rh −chloro complex [(η -
C Me )Rh (bpy)Cl](Cl) (3(Cl)) with sodium metal in
6 6
1
−6
chemistry. Hydrodefluorination is the reaction that converts
the C−F bonds into C−H bonds and can provide partially
fluorinated molecules as synthetic building blocks for bio-
III
5
III
10
5
5
1a,2−6
8
logically active compounds and functional materials.
994, Aizenberg and Milstein reported the first example of
catalytic” hydrodefluorination by using Rh complexes and
In
THF at room temperature. Whereas the synthesis and
8,9
1
“
characterization of 1 have been reported, the X-ray structure
has not yet been reported. Fortunately, purple crystals of 1
suitable for X-ray diffraction analysis were grown from a
saturated THF solution at room temperature. The molecular
structure of 1 is depicted in Figure 1, along with selected
interatomic data (Table S1 in the Supporting Information).
The Rh atom of 1 is coordinated by the one C ring of C Me
5
R SiH (R = Ph, EtO) as catalysts and hydrogen sources,
3
2
respectively. Since then, various transition-metal catalysts for
hydrodefluorination have been developed in combination with
3
4
hydrogen sources such as silanes, aluminum hydrides,
5
6
pinacolborane, and H . Among them, systems using H as
2
2
5
5
the hydrogen source, which can be referred to as “catalytic C−F
bond hydrogenolysis”, are attractive from fundamental,
economical, and environmental points of view. However, a
limited number of transition-metal catalysts have been reported
so far and, especially for the hydrogenolysis of unreactive
substrates such as hexafluorobenzene (C F ), the systems
and two nitrogen atoms of bpy. Notably, the inter-ring distance
(C15−C16) of the coordinated bpy ligand in 1 (1.423(5) Å) is
consistent with the previously reported theoretical value (1.435
6
6
require the conditions of high H pressure (>0.1 MPa) and/or
2
6
high temperature (>25 °C). To overcome these situations, a
new class of efficient catalysts that can provide a new concept
for the C−F bond hydrogenolysis is required.
Transition-metal complexes of the general composition [(π-
n
arene)M(α-diimine)] (M = Fe(0), Ru(0), Co(I), Rh(I), etc.; n
=
charge of the complex), which have an electron-rich metal
center, have received much attention because of their unique
electronic structures and reactivities.
develop novel reactivities of this class of metal complexes, we
have now found that the Rh(I) complex [(η -C Me )Rh (bpy)]
7
−9
In our efforts to
7a
Figure 1. ORTEP drawing of 1 with 50% probability ellipsoids.
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
5
I
5
5
5
angle (deg): average Rh1−C(η -C Me ) = 2.204(4), Rh1−N1 =
(
1; bpy = 2,2′-bipyridine) catalyzes the C−F bond hydro-
5
5 ring
1
.997(3), Rh1−N2 = 2.003(3), C15−C16 = 1.423(5), N1−Rh1−N2
genolysis of C F under mild conditions (0.1 MPa of H , 25 °C).
Herein we report the catalytic reactivity of 1 toward
fluoroaromatics (C F CF , C F , C F H, and C F CH ),
6
6
2
=
78.21(11).
6
5
3
6
6
6
5
6
5
3
together with a hitherto unknown crystal structure of 1. We
also report the successful isolation of the C−F bond cleavage
Received: June 18, 2014
Published: August 19, 2014
©
2014 American Chemical Society
4349
dx.doi.org/10.1021/om500647h | Organometallics 2014, 33, 4349−4352

Organometallics
Communication
9
a
Å) and is much shorter than that of the uncoordinated bpy
source was further supported by the labeling experiment using
1
1
(
(
1.490(3) Å). This is the structural evidence for the ligand
bpy) reduction discussed in the structurally related [(π-
arene)M(α-diimine)] complexes.
D (Table 1, entry 9). Notably, the double-hydrogenolysis
2
product “p-HC F H” is obtained by the chemo- and
6
4
n
7a,b,d,h,9a,b
So far, this class of
regioselective hydrogenolysis of C F H (Tables S2 and S3,
6 5
metal complexes has not been applied to the C−F bond
activation.
Table 1, and Figures S1 and S2 in the Supporting
12
Information).
The catalytic ability of 1 (5 mol %) toward the C−F bond
hydrogenolysis of C F with 0.1 MPa of H at 25 °C for 24 h
The catalytic C−F bond hydrogenolysis of other fluoroar-
omatics was also investigated under mild conditions (Table 2
6
6
2
was investigated under various conditions (Tables S2 and S3 in
the Supporting Information). The effect of solvent was
examined using toluene, THF, 1,2-dimethoxyethane (DME),
CH OH, CH CN, and DMSO (Table S2). The effect of the
Table 2. Catalytic C−F Bond Hydrogenolysis of
Fluoroaromatics in CH CN under Mild Conditions (0.1
3
a
3
3
MPa of H , 25 °C, 24 h)
2
base that works as a trap for the released HF was also examined
6
using Cs CO , pyridine, Et N, and Et NH (Table S3). The
2
3
3
2
over 99% conversion of C F with a turnover number (TON, in
6
6
units of (mol of product)/(mol of catalyst)) of 19.8 for C F H
6
5
was obtained by using CH CN and Et NH as a solvent and
3
2
base, respectively (Table S3, entry 4, and Table 1, entry 1). The
b
b
entry
1
X
base (amt (equiv))
TON
conversn (%)
Table 1. Catalytic C−F Bond Hydrogenolysis of C F in
6
6
CF3
Et N (2)
3
5.2
19.8
10.2
3.8
26
99
51
19
a
CH CN
c
3
2
F
Et NH (2)
2
3
4
H
Et NH (2)
2
CH3
Et NH (2)
2
a
The catalytic reactions were investigated using 0.5 mmol (200 mM)
b
of C F X (X = CF , F, H, CH ). Turnover numbers (TON, in units
6
5
3
3
of (mol of single hydrogenolysis product)/(mol of catalyst)) and
conversions (conversn (%)) were determined by integration of the
peaks in the F NMR spectra using 0.25 mmol of 1-fluoropentane as
b
19
TON
an internal standard (precision limits are ±3% of the given value).
The same data of Table 1, entry 1.
amt of cat.
(mol %)
H (MPa),
p-
6 4
conversn
2
c
d
b
c
entry
time (h)
C F H HC F H
(%)
6
5
e
1
1 (5)
0.1, 24
0.1, 24
0.1, 24
0.8, 24
0.8, 48
0.8, 48
0.8, 24
−, 24
19.8
19.0
24.8
38.0
93.0
380
3.9
2.5
0.9
5.3
99
95
62
95
93
38
f
2
1 (5)
and Figures S3−S5 in the Supporting Information). In general,
the hydrodefluorination of the electron-rich fluoroaromatics is
3
4
5
6
7
8
1 (2.5)
1 (2.5)
1 (1)
3
b,d
difficult and the examples are very rare.
The reaction of
13
10.7
C F CF , C F H, and C F CH with 0.1 MPa of H in the
6
5
3
6
5
6
5
3
2
1 (0.1)
−
1 (2.5)
1 (2.5)
2(F) (2.5)
3(Cl) (2.5)
5.7
presence of 1 (5 mol %) and base provided the selective C−F
bond hydrogenolysis products (p-HC F CF , p-HC F H, and
g
n.r.
6
4
3
6 4
g
n.r.
p-HC F CH ) with conversions of 26, 51, and 19%,
6 4 3
12
h
i
9
0.1, 24
0.1, 24
0.8, 24
29.2
26.8
37.2
1.3
1.2
4.7
73
67
93
respectively. Thus, 1 can catalyze the C−F bond hydro-
genolysis of fluoroaromatics both more electron deficient
(C F CF ) and rich (C F H and C F CH ) than C F ; 1
1
1
0
1
6
5
3
6
5
6
5
3
6 6
a
cannot catalyze the reaction of fluoroaromatics (p-HC F H)
The catalytic reactions were investigated in CH CN under various
6 4
3
conditions (0.1 or 0.8 MPa of H , 25 °C, 24 or 48 h) using 0.5 mmol
more electron rich than C F CH (5 mol % of 1, 0.1 MPa of
6 5 3
2
b
(
200 mM) of C F . Turnover numbers (TON, in units of (mol of
H , 25 °C, 24 h).
2
6
6
product)/(mol of catalyst)) and conversions (conversn (%)) were
A clue to elucidate the catalytic cycle has been obtained by
the isolation of the C−F bond cleavage product 2(F). The
reaction of 1 with C F “without H ” at room temperature
determined by integration of the peaks in the 19F NMR spectra using
0
.25 mmol of 1-fluoropentane as an internal standard (precision limits
c
6
6
2
are ±3% of the given value). TON for C F H: ((mol of C F H) +
6
5
6 5
afforded 2(F). The monocationic Rh(III) complex 2 was
d
(
mol of p-HC F H))/(mol of catalyst). TON for p-HC F H: (mol of
1
19
6
4
6 4
e
characterized by NMR ( H and F) and UV−vis−NIR
spectroscopy, electrospray ionization mass spectrometry (ESI-
MS), X-ray diffraction, and elemental analysis (Figures S6−S8
in the Supporting Information). The positive-ion ESI mass
p-HC F H)/(mol of catalyst). The same data of Table S3, entry 4
6
4
f
(Supporting Information). The reaction was carried out in the
g
h
presence of an Hg drop (ca. 60 mg). No reaction. D (99.5%) was
used instead of H . Molar ratio of the products: C F D/C F H = 90/
1
2
i
2
6
5
6 5
0 (Figure S2 in the Supporting Information); C F H may be
spectrum of 2(F) dissolved in CH CN shows a signal at m/z
3
6
5
produced by D/H exchange at a certain stage in step II in Scheme 1.
561.2 (relative intensity (I) = 100% in the range m/z 200−
1
200), which has a characteristic isotopic distribution that
result of Hg(0) drop experiments indicates that there is no
heterogeneous metal particle under the present reaction
conditions (Table 1, entries 1 and 2). Further optimization
showed that the best TON of 380 for C F H was afforded by
matches well with the calculated isotopic distribution for the
monocation 2.
The molecular structure of 2 was confirmed by X-ray
crystallography (Table S1). Yellow crystals of 2(BPh )·Et O
6
5
4
2
using 0.1 mol % of 1, 0.8 MPa of H , and 1.0 mmol of Et NH
were obtained by diffusion of Et O into an AcOEt/CH CN (5/
2
2
2
3
(
2 equiv) (Table 1, entry 6). The blank experiments without
1) solution of 2(BPh ) which was prepared by anion exchange
4
the catalyst or H did not yield any products (Table 1, entries 7
of 2(F) with NaBPh in THF. Figure 2 shows an ORTEP
2
4
and 8). The necessity of H as a hydrogen and an electron
drawing of the monocationic Rh(III) complex 2. The Rh atom
2
4
350
dx.doi.org/10.1021/om500647h | Organometallics 2014, 33, 4349−4352

Organometallics
Communication
Scheme 1. Plausible Catalytic Cycle for the C−F Bond
Hydrogenolysis of C F by 1
6
6
Figure 2. ORTEP drawing of monocation 2 with 50% probability
ellipsoids. Hydrogen atoms, solvent, and BPh anion are omitted for
4
clarity. Selected bond lengths (Å) and angle (deg): average Rh1−
5
C(η -C Me )
2
=
= 2.182(4), Rh1−C21 = 2.099(4), Rh1−N1 =
5
5
ring
.111(3), Rh1−N2 = 2.104(3), C15−C16 = 1.471(4), N1−Rh1−N2
77.11(10).
of 2 is coordinated by the one C ring of C Me , two nitrogen
5
5
5
atoms of bpy, and one carbon atom of C F . The inter-ring
6
5
distance (C15−C16) of the coordinated bpy ligand in 2
(
(
1.471(4) Å) is longer than that of the Rh(I) complex 1
III
1.423(5) Å) and is consistent with that of the Rh −chloro
1
0
complex 3 (1.480(11) Å). The metal−perfluoroarene
distance (Rh1−C21) in 2 (2.099(4) Å) is slightly longer than
5
III
species in the catalytic cycle, because some Rh(III) complexes
that found in [(η -C Me )Rh (PMe )(C F )Cl] (2.070(5)
5
5
3
6 5
III
21
1
4
are known to react with H to form Rh −H species. Further
Å).
2
studies to elucidate the reaction mechanism are now in
progress.
The reaction of 2(F) with 0.1 MPa of H in the presence of
2
Et NH in CH CN at 25 °C yielded the Rh(I) complex 1,
2
3
In conclusion, we have demonstrated that the Rh(I) complex
C F H, and p-HC F H (Figure S9 in the Supporting
6
5
6 4
1
is a new class of efficient catalyst for C−F activation. To date,
Information). Furthermore, 2(F) catalyzed the hydrogenolysis
of C F with much the same efficiency and selectivity as 1
the development of transition-metal catalysts for C−F bond
6
6
activation has been mainly focused on metal hydride and
(
Table 1, entries 3 and 10). Thus, 2(F) must be one of the
1
−6
fluoride species as catalysts or intermediates. We believe that
our findings offer attractive new insight into the construction of
novel efficient catalysts, not only for the hydrogenolysis of
fluoroaromatics but also for the further functionalization of
fluoroorganic compounds.
intermediates in the catalytic cycle. The base (Et NH) likely
2
assists heterolytic cleavage of H , as discussed in the H
activation chemistry.
2
2
15
Scheme 1 shows a plausible catalytic cycle for the C−F bond
hydrogenolysis of C F by the Rh(I) complex 1 on the basis of
6
6
the findings described above. In step I, 1 reacts with the
substrate “C F ” to form the C F -coordinated Rh(III) complex
ASSOCIATED CONTENT
Supporting Information
Text, tables, figures, and CIF files giving experimental details
and characterization data for 1, 2(F), and 2(BPh ) and X-ray
crystallographic data for 1 and 2(BPh )·Et O. This material is
available free of charge via the Internet at http://pubs.acs.org.
6
6
6
5
■
2. The reaction likely proceeds via a nucleophilic aromatic
*
S
substitution (S Ar) pathway that is proposed in the reaction of
N
5
I
the neutral Ir(I) complex [(η -C Me )Ir (CO) ] with
C F CN, whereas an electron-transfer
addition pathway cannot be excluded at the present stage. In
5
5
2
4
1
6
2,6d,17
and oxidative-
6
5
4
2
1
8
step II, 2 reacts with H to liberate the product “C F H” and
2
6 5
III
may transfer to a Rh −H species. The reaction includes Rh−C
and H−H bond cleavage and Rh−H and C−H bond formation
processes and may proceed with ring slippage of the C Me
ligand. The rate-determining step is involved in this step, as
supported by the following observations: (i) the solution during
the catalytic reaction is pale yellow due to 2 (Figures S1 and
AUTHOR INFORMATION
Corresponding Authors
E-mail for H.N.: nakai@mail.cstm.kyushu-u.ac.jp.
E-mail for S.O.: ogo.seiji.872@m.kyushu-u.ac.jp.
■
*
*
5
5
1
9
Notes
The authors declare no competing financial interest.
S9) and (ii) the TON increases with increasing H pressure
2
III
(
Table 1, entries 3 and 4). In step III, the Rh −H species
ACKNOWLEDGMENTS
reacts with the base to regenerate 1 (deprotonation of hydride
species). The following points should be noted. (i) 1 does not
■
2
0
This work was supported by grants-in-aid 26000008 (Specially
Promoted Research), 26410074, 26810038, and 24109016
(Scientific Research on Innovative Areas “Stimuli-responsive
Chemical Species”) and the World Premier International
Research Center Initiative (WPI Program) from the Ministry
of Education, Culture, Sports, Science and Technology
(MEXT, Japan).
react with 0.8 MPa of H in the presence of Et NH: the
2
2
possibility for the oxidative addition of H to the Rh(I) center
2
can be excluded under the catalytic conditions (Figure S10 in
III
the Supporting Information) (ii) The practically useful Rh −
chloro complex 3 can catalyze the hydrogenolysis of C F
6
6
III
(Table 1, entry 11): this supports the formation of the Rh −H
4
351
dx.doi.org/10.1021/om500647h | Organometallics 2014, 33, 4349−4352

Organometallics
Communication
(
14) Belt, S. T.; Helliwell, M.; Jones, W. D.; Partridge, M. G.; Perutz,
REFERENCES
■
R. N. J. Am. Chem. Soc. 1993, 115, 1429.
15) (a) Ogo, S.; Ichikawa, K.; Kishima, T.; Matsumoto, T.; Nakai,
(
1) Reviews: (a) Kuehnel, M. F.; Lentz, D.; Braun, T. Angew. Chem.,
Int. Ed. 2013, 52, 3328. (b) Stahl, T.; Klare, H. F. T.; Oestreich, M.
ACS Catal. 2013, 3, 1578. (c) Klahn, M.; Rosenthal, U. Organometallics
012, 31, 1235. (d) Clot, E.; Eisenstein, O.; Jasim, N.; Macgregor, S.
A.; McGrady, J. E.; Perutz, R. N. Acc. Chem. Res. 2011, 44, 333.
e) Amii, H.; Uneyama, K. Chem. Rev. 2009, 109, 2119. (f) Torrens, H.
Coord. Chem. Rev. 2005, 249, 1957.
2) Aizenberg, M.; Milstein, D. Science 1994, 265, 359.
3) Selected publications: (a) Chen, Z.; He, C.-Y.; Yin, Z.; Chen, L.;
He, Y.; Zhang, X. Angew. Chem., Int. Ed. 2013, 52, 5813. (b) Lv, H.;
Cai, Y.-B.; Zhang, J.-L. Angew. Chem., Int. Ed. 2013, 52, 3203.
(
H.; Kusaka, K.; Ohhara, T. Science 2013, 339, 682. (b) Liu, T.; DuBois,
D. L.; Bullock, R. M. Nat. Chem. 2013, 5, 228. (c) Kubas, G. J. Chem.
Rev. 2007, 107, 4152.
2
(
(
16) Chan, P. K.; Leong, W. K. Organometallics 2008, 27, 1247.
17) (a) Senaweera, S. M.; Singh, A.; Weaver, J. D. J. Am. Chem. Soc.
(
2
014, 136, 3002. (b) Whittlesey, M. K.; Perutz, R. N.; Moore, M. H.
(
(
Chem. Commun. 1996, 787. (c) Blum, O.; Frolow, F.; Milstein, D. J.
Chem. Soc., Chem. Commun. 1991, 258.
(
Chem. Soc., Dalton Trans. 2002, 297. (b) Richmond, T. G.; Osterberg,
C. E.; Arif, A. M. J. Am. Chem. Soc. 1987, 109, 8091.
(
(
18) (a) Sladek, M. I.; Braun, T.; Neumann, B.; Stammler, H.-G. J.
(
2
c) Fischer, P.; Go
012, 31, 1374. (d) Zhan, J.-H.; Lv, H.; Yu, Y.; Zhang, J.-L. Adv. Synth.
Catal. 2012, 354, 1529. (e) Kuhnel, M. F.; Lentz, D. Angew. Chem., Int.
̈
tz, K.; Eichhorn, A.; Radius, U. Organometallics
19) Ogo, S. Chem. Commun. 2009, 3317.
5
III
+
̈
20) The deprotonation of [(η -C Me )Rh (bpy)H] has been
5
5
Ed. 2010, 49, 2933. (f) Reade, S. P.; Mahon, M. F.; Whittlesey, M. K. J.
Am. Chem. Soc. 2009, 131, 1847. (g) Vela, J.; Smith, J. M.; Yu, Y.;
Ketterer, N. A.; Flaschenriem, C. J.; Lachicotte, R. J.; Holland, P. L. J.
Am. Chem. Soc. 2005, 127, 7857.
discussed: Fukuzumi, S.; Kobayashi, T.; Suenobu, T. ChemSusChem
008, 1, 827.
(21) (a) Hu, Y.; Norton, J. R. J. Am. Chem. Soc. 2014, 136, 5938.
(b) Himeda, Y.; Onozawa-Komatsuzaki, N.; Sugihara, H.; Arakawa, H.;
Kasuga, K. Organometallics 2004, 23, 1480. (c) Harrod, J. F.; Halpern,
J. Can. J. Chem. 1959, 37, 1933.
2
(
4) (a) Yow, S.; Gates, S. J.; White, A. J. P.; Crimmin, M. R. Angew.
Chem., Int. Ed. 2012, 51, 12559. (b) Fuchibe, K.; Ohshima, Y.; Mitomi,
K.; Akiyama, T. Org. Lett. 2007, 9, 1497. (c) Jager-Fiedler, U.; Klahn,
̈
M.; Arndt, P.; Baumann, W.; Spannenberg, A.; Burlakov, V. V.;
Rosenthal, U. J. Mol. Catal. A 2007, 261, 184.
(
5) (a) Breyer, D.; Braun, T.; Penner, A. Dalton Trans. 2010, 39,
513. (b) Braun, T.; Salomon, M. A.; Altenhoner, K.; Teltewskoi, M.;
Hinze, S. Angew. Chem., Int. Ed. 2009, 48, 1818.
6) (a) Yang, H.; Gao, H.; Angelici, R. J. Organometallics 1999, 18,
7
̈
(
2
2
7
8
285. (b) Young, R. J., Jr.; Grushin, V. V. Organometallics 1999, 18,
94. (c) Edelbach, B. L.; Jones, W. D. J. Am. Chem. Soc. 1997, 119,
734. (d) Aizenberg, M.; Milstein, D. J. Am. Chem. Soc. 1995, 117,
674. (e) Catalytic C−F bond hydrogenolysis of pentafluoropyridine
(
C F N) that contains activated C−F bonds has been observed under
5
5
mild conditions (atmospheric pressure of H , room temperature):
2
Braun, T.; Noveski, D.; Ahijado, M.; Wehmeier, F. Dalton Trans. 2007,
3820.
(
7) (a) Jeong, K.; Nakamori, H.; Imai, S.; Matsumoto, T.; Ogo, S.;
Nakai, H. Chem. Lett. 2012, 41, 650. (b) Mork, B. V.; McMillan, A.;
Yuen, H.; Tilley, T. D. Organometallics 2004, 23, 2855. (c) Suenobu,
T.; Guldi, D. M.; Ogo, S.; Fukuzumi, S. Angew. Chem., Int. Ed. 2003,
42, 5492. (d) Lenges, C. P.; White, P. S.; Marshall, W. J.; Brookhart,
M. Organometallics 2000, 19, 1247. (e) Ziessel, R.; Noblat-Chardon,
S.; Deronzier, A.; Matt, D.; Toupet, L.; Balgroune, F.; Grandjean, D.
Acta Crystallogr., Sect. B 1993, B49, 515. (f) Ziessel, R. J. Am. Chem.
Soc. 1993, 115, 118. (g) Ladwig, M.; Kaim, W. J. Organomet. Chem.
1
992, 439, 79. (h) Radonovich, L. J.; Eyring, M. W.; Groshens, T. J.;
Klabunde, K. J. J. Am. Chem. Soc. 1982, 104, 2816.
8) (a) Kolle, U.; Kang, B.-S.; Infelta, P.; Comte, P.; Grat
Chem. Ber. 1989, 122, 1869. (b) Kolle, U.; Grutzel, M. Angew. Chem.,
Int. Ed. Engl. 1987, 26, 567.
9) (a) Scarborough, C. C.; Wieghardt, K. Inorg. Chem. 2011, 50,
773. (b) Sieger, M.; Kaim, W.; Stufkens, D. J.; Snoeck, T. L.; Stoll,
H.; Zalis, S. Dalton Trans. 2004, 3815. (c) Kaim, W.; Reinhardt, R.;
Waldhor, E.; Fiedler, J. J. Organomet. Chem. 1996, 524, 195. (d) Kaim,
(
̈
̈
zel, M.
̈
̈
(
9
́
̈
W.; Reinhardt, R.; Sieger, M. Inorg. Chem. 1994, 33, 4453. (e) Ladwig,
M.; Kaim, W. J. Organomet. Chem. 1991, 419, 233.
(
10) Dadci, L.; Elias, H.; Frey, U.; Ho
̈
rnig, A.; Koelle, U.; Merbach,
A. E.; Paulus, H.; Schneider, J. S. Inorg. Chem. 1995, 34, 306.
(
11) The uncoordinated bpy has a C−C bond length of 1.490(3) Å:
Chisholm, M. H.; Huffman, J. C.; Rothwell, I. P.; Bradley, P. G.; Kress,
N.; Woodruff, W. H. J. Am. Chem. Soc. 1981, 103, 4945.
(
12) C F X compounds undergo fluorine nucleophilic substitution as
6 5
a rule at the para position: Shteingarts, V. D. J. Fluorine. Chem. 2007,
28, 797.
13) As a base, Et N was used for the hydrogenolysis of C F CF
1
(
3
6
5
3
because Et NH directly reacts with electron-deficient “C F CF ” to
2
6
5
3
produce p-Et NC F CF : Frohn, H. J.; Bardin, V. V. Z. Anorg. Allg.
2
6
4
3
Chem. 1996, 622, 2031.
4
352
dx.doi.org/10.1021/om500647h | Organometallics 2014, 33, 4349−4352