C-F activation and hydrodefluorination of fluorinated alkenes at rhodium

Article abstract of DOI:10.1039/b306635e

Reaction of [RhH(PEt₃)₄] (9) with hexafluoropropene (1) affords the C-F activation product [Rh{(Z)-CF=CF(CF₃)}(PEt₃)₃] (4) as well as Et₃P(F){(Z)-CF=CF(CF₃)} (11). In contrast, addition of (E)-1,2,3,3,3-pentafluoropropene (8) to 9 yields [Rh{(E)-C(CF₃)=CHF}(PEt₃)₃] (12) together with [RhF(PEt₃)₃] (6) and (Z)-1,3,3,3-tetrafluoropropene (10). Treatment of 12 with hydrogen effects the formation of 1,1,1-trifluoropropane (2) and the fluoro compounds [RhF(PEt₃)₃] (6) and cis-mer-[Rh(H)₂F(PEt₃)₃] (7). On treatment of 6 or of a mixture of 6 and 7 with HSiPh₃ the complexes [RhH(PEt₃)₃] (3) and cis-fac-[Rh(H)₂(SiPh₃)(PEt₃)₃] (13) are obtained. Both compounds are capable of the C-F activation of hexafluoropropene (1) to afford 4. The molecular structure of complex 13 has been determined by X-ray crystallography.

Full text of DOI:10.1039/b306635e

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C–F Activation and hydrodefluorination of fluorinated alkenes at
rhodium†
Daniel Noveski, Thomas Braun,* Miriam Schulte, Beate Neumann and Hans-Georg Stammler
Fakultät für Chemie, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany.
E-mail: thomas.braun@uni-bielefeld.de
Received 11th June 2003, Accepted 11th July 2003
First published as an Advance Article on the web 22nd September 2003
Reaction of [RhH(PEt3)4] (9) with hexafluoropropene (1) affords the C–F activation product
[Rh{(Z)-CF᎐CF(CF )}(PEt ) ] (4) as well as Et P(F){(Z)-CF᎐CF(CF )} (11). In contrast, addition of
᎐
᎐
3
3
3
3
3
(E)-1,2,3,3,3-pentafluoropropene (8) to 9 yields [Rh{(E)-C(CF )᎐CHF}(PEt ) ] (12) together with [RhF(PEt ) ]
᎐
3
3
3
3 3
(6) and (Z)-1,3,3,3-tetrafluoropropene (10). Treatment of 12 with hydrogen effects the formation of 1,1,1-trifluoro-
propane (2) and the fluoro compounds [RhF(PEt3)3] (6) and cis-mer-[Rh(H)2F(PEt3)3] (7). On treatment of 6 or of a
mixture of 6 and 7 with HSiPh3 the complexes [RhH(PEt3)3] (3) and cis-fac-[Rh(H)2(SiPh3)(PEt3)3] (13) are obtained.
Both compounds are capable of the C–F activation of hexafluoropropene (1) to afford 4. The molecular structure of
complex 13 has been determined by X-ray crystallography.
Introduction
There has been considerable interest in the activation of
carbon–fluorine bonds at transition metal centres in the last
few years.1–15 However, the formation of organofluorine
compounds via C–F activation is still little developed. Recent
examples include the stoichiometric4,5 and catalytic6–9
derivatisation of aromatic compounds by C–F activation. Thus,
the catalytic conversion of hexafluorobenzene into penta-
fluorobenzene in the presence of hydrogen using a rhodium
catalyst has been reported.8 Comparable hydrodefluorination
reactions at fluorinated alkenes are sparse and often not very
selective.1,10–14 The reactions include mainly the transformation
of monofluorinated alkenes.13
The selective hydrodefluorination of perfluorinated alkenes
remains a major challenge. However, a breakthrough has been
reported very recently by W. D. Jones and coworkers. They
described the conversion of highly fluorinated alkenes into less
fluorinated derivatives using [(η5-C5Me5)2ZrH2] as the hydrogen
source.10,11 Note also that M. K. Whittlesey et al. showed that
the reaction of hexafluoropropene with a ruthenium dihydride
leads to a mixture of less fluorinated alkenes.12 Recently, we
achieved the conversion of hexafluoropropene (1) into 1,1,1-
Scheme 1 C–F activation and hydrodefluorination of hexafluoro-
trifluoropropane (2) by rhodium induced hydrodefluorination
propene (1)
(Scheme 1).15 The reaction proceeds selectively and is very
unique, because there is no indication of a defluorination of the
trifluoromethyl group. The key step of the transformation is the
activation of the fluorinated alkene at [RhH(PEt3)3] (3) yield-
Results
1
Synthesis of fluoropropenyl complexes
ing [Rh{(Z)-CF᎐CF(CF )}(PEt ) ] (4). Oxidative addition
᎐
3
3 3
of hydrogen at 4 affords the rhodium() complex cis-mer-
Treatment of [RhH(PEt3)4] (9) with hexafluoropropene (1) in
the presence of triethylamine and Cs2CO3 affords the C–F
[Rh(H) {(Z)-CF᎐CF(CF )}(PEt ) ] (5). The dihydrido com-
᎐
2
3
3 3
pound 5 converts in the presence of hydrogen into 2 and
the fluoro complexes [RhF(PEt3)3] (6) and cis-mer-[Rh(H)2-
F(PEt3)3] (7).
activation product [Rh{(Z)-CF᎐CF(CF )}(PEt ) ] (4) together
᎐
3
3 3
with the phosphorane Et P(F){(Z)-CF᎐CF(CF )} (11)16
᎐
3
3
(Scheme 2).
In this paper we describe studies on the activation and hydro-
defluorination of hexafluoropropene (1) and (E)-1,2,3,3,3-
pentafluoropropene (8) at [RhH(PEt3)4] (9). In the latter case a
metal derivative of the alkene as well as the hydrodefluorination
product (Z)-1,3,3,3-tetrafluoropropene (10) has been obtained.
Moreover, a cyclic process for the rhodium-mediated hydro-
defluorination of 1 yielding 2 has been developed. Rhodium
compounds, which are again suitable for C–F activation can
be regained on treatment of [RhF(PEt3)3] (6) and cis-mer-
[Rh(H)2F(PEt3)3] (7) with a silane.
In contrast, a reaction of (E)-1,2,3,3,3-pentafluoropropene
(8) with [RhH(PEt3)4] (9) in the presence of the same combin-
ation of bases yields the fluoropropenyl complex [Rh{(E)-
C(CF )᎐CHF}(PEt ) ] (12), the rhodium() fluoro compound
᎐
3
3 3
[RhF(PEt3)3] (6) as well as the alkene (Z)-1,3,3,3-tetrafluoro-
propene (10)17 in a ratio ≈ 1 : 1 : 1 (Scheme 2). Furthermore
there are traces (≈5%) of compound 4, presumably generated by
C–H activation. There is no indication for the formation of a
phosphorane. Somewhat surprisingly, treatment of the phos-
phorane Et P(F){(Z)-CF᎐CF(CF )} (11) with the hydrido
᎐
3
3
compound 9 also leads to the propenyl complex 12 and the
rhodium fluoride 6 (ratio ≈ 1 : 1) as well as to considerable
amounts of F2PEt3 18 (Scheme 2).
† Based on the presentation given at Dalton Discussion No. 6, 9–11th
September 2003, University of York, UK.
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
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Scheme 2 Formation of fluoropropenyl complexes
Compounds 4 and 6 have been described before and have
been characterised by their NMR data.15 In addition we also
acquired a 19F–13C HMQC NMR spectrum of 4 to get some
information on the chemical shifts of the signals for the pro-
penyl ligand in the 13C NMR spectrum. The 2D spectrum
shows a cross-peak which connects the signal for the fluorines
of the CF3 group to a resonance at δ(13C) 122. It also exhibits a
strong correlation of the fluorine at δ(19F) Ϫ174.4 to a carbon
centre at δ(13C) 146 and of the fluorine at δ(19F) Ϫ95.4 to a
carbon nucleus at δ(13C) 200. We assign the latter signal to the
CF moiety in the α-position of the vinyl ligand.19 The appear-
ance of the correlation peak to the β-carbon atom at the inter-
section to δ(13C) 146 is consistent with previous assignments of
the resonance at higher field in the 19F NMR spectrum to the
fluorine in the β-position in perfluoropropenyl ligands.20,21
The 31P NMR spectrum of 12 is of higher order and has been
simulated (Fig. 1).22 The coupling constants determined
proton and the fluorine atom at the double bond.17,23–26
Furthermore, the signals in the 19F NMR spectrum exhibit a
coupling between the fluorines at the trifluoromethyl group and
the olefinic fluorine with a coupling constant of 16 Hz. This
suggests a cis configuration of a trifluoromethyl moiety in
α-position and the olefinic fluorine.21,26 More evidence for the
configuration at the double bond in 12 is given by 1H–13C
HMQC and 19F–13C HMQC NMR spectra (Fig. 2). In the
1H–13C NMR spectrum there is a strong correlation of the
proton at δ(1H) 7.27 with a carbon atom at δ(13C) 143. The
19F–13C NMR spectrum shows a cross-peak connecting the
resonance for the fluorine at δ(19F) Ϫ118.0 also with the inter-
section to δ(13C) 143 (Fig. 2). This observation clearly proves
the geminal position of the olefinic fluorine and proton at the
β-carbon atom. Finally, a 19F–13C HMQC/HMBC NMR spec-
trum reveals the chemical shift for the signal of the α-carbon
atom of the propenyl ligand at δ(13C) 236 (Fig. 3). Overall, we
assign the configuration at the double bond in 12 as (E)-
RhC(CF )᎐CHF (Scheme 2).
resemble these found for [Rh{(Z)-CF᎐CF(CF )}(PEt ) ] (4),
᎐
3
3 3
except for the coupling JP ,F = 19.8 Hz.15 This value might
reflect the trans position of the olefinic fluorine to the rhodium
at the double bond. The 19F NMR spectrum of 12 displays a
resonance at δ Ϫ68.6 for the fluorine atoms of the CF3 group
and a signal at δ Ϫ118.0 with a coupling to the olefinic proton
of 77 Hz. In the 1H NMR spectrum the resonance for the
olefinic proton can be found at δ 7.27 with the same coupling
constant. This value indicates a geminal configuration of the
b
᎐
3
2
Reactivity of fluoropropenyl complexes
Investigations by NMR spectroscopy reveal that addition of
hydrogen to a solution of [Rh{(E)-C(CF )᎐CHF}(PEt ) ] (12)
᎐
3
3 3
leads to the generation of 1,1,1-trifluoropropane (2) as well as
to the fluoro complexes [RhF(PEt3)3] (6) and cis-mer-[Rh(H)2-
F(PEt3)3] (7) (Scheme 3). This conversion resembles the reac-
tion of [Rh{(Z)-CF᎐CF(CF )}(PEt ) ] (4) with hydrogen,
᎐
3
3 3
which has been described in the introduction. We proved in an
independent experiment that 7 is formed by oxidative addition
of H2 to 6. Complex 7 is only stable in solution and readily loses
hydrogen under vacuum.
The rhodium–carbon bond in 4 can not only be cleaved with
hydrogen (Scheme 1), but also on treatment of a solution of
4 with Et3Nؒ3HF yielding an alkene. An NMR experiment
showed that on using substoichiometric amounts of “HF” the
fluoro compound [RhF(PEt3)3] (6) and the (E)-1,2,3,3,3-penta-
fluoropropene (8) are generated (Scheme 3).
3
Synthesis, molecular structure and reactivity of cis-fac-
[Rh(H)2(SiPh3)(PEt3)3] (13)
A reaction of complex [RhF(PEt3)3] (6) with a slight excess of
HSiPh3 gives FSiPh3 and compound [RhH(PEt3)3] (3) as well as
minor amounts (5–10%) of the silyl complex cis-fac-[Rh(H)2-
(SiPh3)(PEt3)3] (13) (Scheme 4). If a larger excess of HSiPh3 is
used, the amount of 13 increases. In an independent reaction
Fig. 1 31P{1H} NMR spectrum of complex 12; simulated (below) and
1
a
observed (above) using the following coupling constants (Hz): JRhP
=
3
2
1
3
a
a
b
b
b
139.5, JP F = 5.1, JP P = 39.1, JRhP = 126.5, JP F = 19.8; labeling of
atoms as shown in Scheme 2.
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
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Scheme 3 Reactivity of fluoropropenyl complexes.
Fig. 2 Left: 1H{13C}–13C HMQC NMR spectrum of 12, * indicates C6D5H, the signal at δ(1H) exhibits the 1H,19F-coupling of 77 Hz; right:
19F{1H}–13C HMQC NMR spectrum of 12, one-bond correlations show a large 19F,13C-coupling.
Fig. 3 19F{1H}–13C HMQC/HMBC NMR spectrum of 12, optimised
on long-range couplings, no supression of one-bond correlations.
[RhH(PEt3)4] (9) was also treated with HSiPh3 yielding 13,
which indicates that the silyl complex is formed by oxidative
Fig. 4 An ORTEP diagram of 13. Ellipsoids are drawn at the 50%
addition of HSiPh3 at [RhH(PEt3)3] (3). Moreover, we could
probability level. Only one of the three independent molecules in the
show that a mixture of 6 and the dihydrido compound cis-mer-
asymmetric unit is shown.
[Rh(H)2F(PEt3)3] (7) gives also 3 together with 13.27
The 31P NMR spectrum of 13 displays a doublet of doublets
Si–Rh–P angles are considerably larger than 90Њ. The rhodium-
silicon bond lengths in all three molecules are longer than the
at δ 11.6 and a doublet of triplets at δ 4.2. The JP, P coupling of
17 Hz and the JRh,P couplings of 103.3 Hz and 87.2 Hz are
distances found in cis-fac-[Rh(H)2(SiClPh2)(PMe3)3] [2.314(2) Å]
compatible with the assignment as a rhodium() compound.8,15
and cis-fac-[Rh(H)2{Si(C6H4CF3)3}(PMe3)3] [2.338(4) Å].28
1
The multiplet at δ Ϫ10.74 in the H NMR spectrum has a
pattern which implies a large coupling to a phosphorus nucleus
in the trans position and is assigned to the two hydrido ligands
cis to each other.
The molecular structure of 13 determined by X-ray crystal
structure analysis is shown in Fig. 4. Colourless crystals were
obtained from hexane at Ϫ30 ЊC. Selected bond length and angles
are summerised in Table 1. Note that the asymmetric unit con-
tains three independent molecules, only one of which is shown as
an ORTEP diagram. The phosphine ligands occupy the three
facial coordination sites of a highly distorted octahedron at
rhodium. The P–Rh–P angles to the cis phosphines as well as the
On treatment of a solution of 13 with hexafluoropropene
complex [Rh{(Z)-CF᎐CF(CF )}(PEt ) ] (4) is formed together
᎐
3
3 3
with considerable amounts of FSiPh3 (Scheme 4). A similar
reaction is observed when a mixture of [RhH(PEt3)3] (3) and 13
is used as starting material.
Discussion
1
C–F activation of fluorinated alkenes
The C–F activation of fluorinated propene derivatives using
rhodium hydrido complexes is shown in Schemes 1 and 2. The
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
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Table 1 Selected bond lengths (Å) and angles (Њ) of cis-fac-[Rh(H)2(SiPh3)(PEt3)3] (13) with the estimated standard deviations in parentheses
Rh(1)–Si(1)
Rh(1)–P(1)
Rh(1)–P(3)
Rh(1)–P(2)
Rh(1)–H(1A)
Rh(1)–H(1B)
Rh(2)–Si(2)
Rh(2)–P(4)
Rh(2)–P(6)
2.3571(10)
2.3594(10)
2.3609(10)
2.3627(11)
1.52(4)
Rh(2)–P(5)
Rh(2)–H(2A)
Rh(2)–H(2B)
Rh(3)–P(7)
Rh(3)–P(8)
Rh(3)–P(9)
Rh(3)–Si(3)
Rh(3)–H(3A)
Rh(3)–H(3B)
2.3796(9)
1.48(3)
1.47(4)
2.3573(9)
2.3649(9)
2.3700(9)
2.3718(9)
1.54(3)
1.51(5)
2.3548(9)
2.3613(9)
2.3705(9)
1.48(4)
Si(1)–Rh(1)–P(1)
Si(1)–Rh(1)–P(3)
P(1)–Rh(1)–P(3)
Si(1)–Rh(1)–P(2)
P(1)–Rh(1)–P(2)
P(3)–Rh(1)–P(2)
Si(1)–Rh(1)–H(1A)
P(1)–Rh(1)–H(1A)
P(3)–Rh(1)–H(1A)
P(2)–Rh(1)–H(1A)
Si(1)–Rh(1)–H(1B)
P(1)–Rh(1)–H(1B)
P(3)–Rh(1)–H(1B)
P(2)–Rh(1)–H(1B)
H(1A)–Rh(1)–H(1B)
Si(2)–Rh(2)–P(4)
Si(2)–Rh(2)–P(6)
P(4)–Rh(2)–P(6)
Si(2)–Rh(2)–P(5)
P(4)–Rh(2)–P(5)
P(6)–Rh(2)–P(5)
Si(2)–Rh(2)–H(2A)
P(4)–Rh(2)–H(2A)
101.57(4)
99.21(3)
103.47(3)
139.89(4)
104.76(4)
103.39(4)
67.1(14)
166.5(14)
86.2(14)
81.7(14)
73.1(17)
82.0(17)
171.5(17)
81.1(18)
87(2)
100.82(3)
97.89(3)
104.97(3)
142.06(3)
103.66(3)
103.17(3)
67.1(13)
165.5(13)
P(6)–Rh(2)–H(2A)
P(5)–Rh(2)–H(2A)
Si(2)–Rh(2)–H(2B)
P(4)–Rh(2)–H(2B)
P(6)–Rh(2)–H(2B)
P(5)–Rh(2)–H(2B)
H(2A)–Rh(2)–H(2B)
P(7)–Rh(3)–P(8)
85.4(13)
83.4(13)
72.7(16)
82.9(16)
168.9(16)
82.1(16)
86(2)
103.86(3)
103.51(3)
103.84(3)
98.40(3)
143.44(3)
98.59(3)
165.6(12)
82.5(12)
87.1(12)
70.1(12)
85.0(15)
78.2(16)
170.3(16)
75.2(16)
83.7(19)
P(7)–Rh(3)–P(9)
P(8)–Rh(3)–P(9)
P(7)–Rh(3)–Si(3)
P(8)–Rh(3)–Si(3)
P(9)–Rh(3)–Si(3)
P(7)–Rh(3)–H(3A)
P(8)–Rh(3)–H(3A)
P(9)–Rh(3)–H(3A)
Si(3)–Rh(3)–H(3A)
P(7)–Rh(3)–H(3B)
P(8)–Rh(3)–H(3B)
P(9)–Rh(3)–H(3B)
Si(3)–Rh(3)–H(3B)
H(3A)–Rh(3)–H(3B)
Scheme 4 Reactivity of 6 and 13.
reaction of (E)-1,2,3,3,3-pentafluoropropene (8) at [RhH-
(PEt3)4] (9) is distinctively different to the reactivity of hexa-
fluoropropene (1) towards 9. While the latter leads to a metal
at rhodium is therefore presumambly complex 3, which can on
treatment with 1 readily be converted into 4.15
The C–F activation reactions proceed in the presence of Et3N
as a base to trap the HF generated, but the yields are better on
using Et3N and Cs2CO3. Note that adducts of HF and Et3N are
known as fluorinating agents, which can initiate further reactiv-
ity.15,30 This can be avoided by adding Cs2CO3 to the reaction
solution. In this case Et3N serves probably as a phase-transfer
agent.8 It should be mentioned that there are only a few
examples on the activation of a C–F bond in fluorinated
alkenes reported in the literature.1,9–14,31–33 The activation
of hexafluorobenzene yielding [Rh(C6F5)(PMe3)3] has been
described by Aizenberg and Milstein.8
derivative of the alkene [Rh{(Z)-CF᎐CF(CF )}(PEt ) ] (4) and
᎐
3
3 3
the phosphorane Et P(F){(Z)-CF᎐CF(CF )} (11), the alkene 8
᎐
3
3
gives the propenyl complex [Rh{(E)-C(CF )᎐CHF}(PEt ) ] (12),
᎐
3
3 3
but also the fluoro compound [RhF(PEt3)3] (6) and the hydro-
defluorination product (Z)-1,3,3,3-tetrafluoropropene (10). The
generation of the phosphorane 11 on treatment of [RhH(PEt3)4]
(9) with hexafluoropropene (1) can easily be explained by the
liberation of phosphine, because 9 is in equilibrium with [RhH-
(PEt3)3] (3) and PEt3, and it has also been shown that PEt3 reacts
with 1 to give 11.16,29 The reactive species for the C–F activation
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
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Scheme 5 Possible mechanisms of the C–F activation of fluorinated propene derivatives.
Moreover, complex cis-fac-[Rh(H)2(SiPh3)(PEt3)3] (13) also
alkene and not of HF from a possible oxidative addition
product.
We therefore propose an alternative mechanism for the form-
reacts with hexafluoropropene (1) yielding the C–F activation
product 4 (Scheme 4). The concomitant generation of FSiPh3
indicates that a silyl complex is the active species for the C–F
activation of the fluorinated molecule. This is presumably the
rhodium() complex [Rh(SiPh3)(PEt3)3], which might be gener-
ated from 13, but could not be identified yet.9,34 However, an
alternative reaction pathway consists of an initial release of
HSiPh3 from 13 and subsequent C–F activation. The formation
of FSiPh3 could then be explained by a reaction of HSiPh3 with
HF. An independent experiment shows that treatment of
HSiPh3 with Et3Nؒ3HF gives indeed FSiPh3.
Concerning the mechanism of the C–F activation of the
fluorinated propenes at rhodium hydride centres several pos-
sibilties are conceivable. We believe that an initial electron
transfer process from the metal to the fluorinated substrate is
not very likely, because of the unfavourable redox potential of
hexafluoropropene (1).8,9,35,36 Such a process would only be con-
ceivable, if one assumes a precoordination of the fluorocarbon
at the metal or rapid irreversible dissociation of FϪ from a
propenyl anion followed by a deprotonation of the metal.37 We
also exclude a reaction pathway via alkene insertion into the
rhodium-hydrogen bond followed by elimination of HF from
the alkyl complex formed, because it would probably lead to
diastereomers.32,38,39
ation of 4. It consists of the generation of a Meisenheimer
intermediate by nucleophilic attack of the rhodium centre at
the fluorinated molecule (Scheme 5, path b).2,31 Loss of fluoride
followed by deprotonation at the metal centre would then give
complex 3 together with HF. The regioselectivity observed is in
accordance with this assumption as the attack of “organic
nucleophiles” at hexafluoropropene (1) occurs at the expected
position.36,42 In contrast, for a nucleophilic attack of [RhH-
(PEt3)3] (9) at (E)-1,2,3,3,3-pentafluoropropene (8) one would
expect a different isomer of 12 than observed.36,42
Overall, we have indications for two distinctive different
mechanisms for the C–F activation of 1 and 8. Comparable
reaction pathways to the mechanisms discussed above are in
principle all conceivable for the activation of hexafluoro-
propene (1) at [Rh(SiPh3)(PEt3)3]. At the moment, the mechan-
ism for the reaction of Et P(F){(Z)-CF᎐CF(CF )} (11) with
᎐
3
3
[RhH(PEt ) ] (9) yielding [Rh{(E)-C(CF )᎐CHF}(PEt ) ] (12),
᎐
3
4
3
3 3
[RhF(PEt3)3] (6) and F2PEt3 is not clear.
2
Hydrodefluorination of fluorinated propenes
Two different hydrodefluorination reactions have been elabor-
ated involving the C–F activation of (E)-1,2,3,3,3-pentafluoro-
propene (8). Thus, cleavage of the carbon–fluorine bond in 8
leads directly to the formation of the less fluorinated alkene
(Z)-1,3,3,3-tetrafluoropropene (10), but also to the rhodium
In contrast, there are indications for an oxidative addition of
(E)-1,2,3,3,3-pentafluoropropene (8) at rhodium followed by
reductive elimination of HF giving [Rh{(E)-C(CF )᎐CHF}-
᎐
3
(PEt3)3] (12) (Scheme 5, path a).40 Such a mechanism also
explains the formation of the fluoro complex [RhF(PEt3)3] (6)
as well as of (Z)-1,3,3,3-tetrafluoropropene (10). Thus, both
compounds can be be generated after reductive elimination of
the alkene 10 from the initial oxidative addition product. Note
that a reaction pathway via alkene (syn-)insertion into the
rhodium–hydrogen bond and subsequent (syn-)β-fluorine elim-
ination would also lead to 6, but not to 10.41 A stereoselective
reaction would rather give the alkenes (E)-1,3,3,3-tetrafluoro-
propene or 2,3,3,3-tetrafluoropropene.
derivative [Rh{(E)-C(CF )᎐CHF}(PEt ) ] (12) (Scheme 2).
᎐
3
3 3
Beyond, compound 12 converts in the presence of hydrogen
into 1,1,1-trifluoropropane (2) (Scheme 3).
In addition, the activation of 8 and its transformation into 2
is important, because the reactions provide some evidence con-
cerning the mechanism of the transformation of hexafluoro-
propene (1) into 1,1,1-trifluoropropane (2). Thus, the formation
of 2 from 4 might proceed via reductive elimination of 8 from
cis-mer-[Rh(H) {(Z)-CF᎐CF(CF )}(PEt ) ] (5) followed by
᎐
2
3
3 3
For the activation of hexafluoropropene (1), which has been
reported before,15 there is no formation of 6 or of a lower
fluorinated alkene. This does not exclude an analogous
reaction pathway via a rhodium() intermediate yielding [Rh-
repetition of C–F activation and analogous cleavage reactions
(Scheme 6).8 Such a reaction pathway would involve both steps
described above. Hydrogenation of the 3,3,3-trifluoropopene
obtained as initial product affords the 1,1,1-trifluoropropane
(2).43 However, we can not exclude entirely other mechanisms,
which involve α- or β-fluorine elimination reactions with con-
comitant formation of HF and subsequent hydrogenation of
the generated propynyl ligand.3,5,41
{(Z)-CF᎐CF(CF )}(PEt ) ] (4), but it seems to be not very
᎐
3
3 3
likely (Scheme 5). Moreover, the formation of 6 and (E)-
1,2,3,3,3-pentafluoropropene (8) on treatment of 4 with Et3Nؒ
3HF indicates a preference for reductive elimination of an
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
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Scheme 6 Possible mechanisms for the formation of 2.
Scheme 7 Cyclic process for the synthesis of 2 from 1.
The conversions of hexafluoropropene (1) and (E)-1,2,3,3,3-
pentafluoropropene (8) into 2 involve the first examples of a
selective and complete hydrodefluorination of a perfluorinated
alkene, in which only the fluorines at the double bond have been
replaced by hydrogen.10,11,44 Moreover, dihydrogen has been
used for the reduction of the fluorovinyl ligands after the activ-
ation of the alkene at rhodium. Note that in the zirconium
mediated conversion of hexafluoropropene into propane a
zirconium hydride is the main hydrogen source.10
propane (2) can be prepared from hexafluoropropene (1),
HSiPh3 and hydrogen in the coordination sphere of rhodium.
Further studies on the basis of these results and on a possible
reactivity of 4 towards silanes will reveal, if a catalytic process
can be developed.
Conclusions
In conclusion, the hydrodefluorination of (E)-1,2,3,3,3-penta-
fluoropropene (8) yielding (Z)-1,3,3,3-tetrafluoropropene (10)
has been achieved. Furthermore, we demonstrated the selective
transfer of the fluorinated alkenyl unit in 8 into a non-fluorin-
ated alkyl group at rhodium. The reaction proceeds via C–F
activation and hydrodefluorination steps in the presence of H2.
The conversion gives some evidence for the mechanism of a
comparable transformation of hexafluoropropene (1) into
1,1,1-trifluoropropane (2).
In addition, a cyclic process for the hydrodefluorination of 1
has been developed allowing the recovery of rhodium com-
plexes, which are again suitable for C–F activation. Current
studies deal with the development of a catalytic cycle.
We believe that the reactions described respresent a new and
general method to prepare hydrofluorocarbons, some of which
are of current interest as compounds with less or no ozone
depletion potential.46
3
A cyclic process for the hydrodeflorination of
hexafluoropropene
A cylic process for the transformation of hexafluoropropene (1)
into 1,1,1-trifluoropropane (2) has been developed (Scheme 7).
The crucial step after the activation and hydrodefluorination of
the fluorinated substrate is the conversion of the complexes
[RhF(PEt3)3] (6) and [Rh(H)2F(PEt3)3] (7) into the compounds
[RhH(PEt3)3] (3) and cis-fac-[Rh(H)2(SiPh3)(PEt3)3] (13) on
treatment with HSiPh3. Note that other replacements of a
fluoro ligands at late transition metals using silanes reagents
have been described.2,9,45 Compound 13 can also be prepared
independently on treatment of [RhH(PEt3)4] (9) with HSiPh3.
Complex 13 or a mixture of 3 and 13 reacts with hexafluoro-
propene (1) and the C–F activation product [Rh{(Z)-CF᎐
᎐
CF(CF3)}(PEt3)3] (4) is reformed. Overall 1,1,1-trifluoro-
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
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Synthesis of cis-mer-[Rh(H)2F(PEt3)3] (7)
Experimental
A slow stream of hydrogen was passed for 1 min through a
solution of [RhF(PEt3)3] (6) (43 mg, 0.09 mmol) in toluene-d8
(1.5 mL). The 19F and 31P NMR data of the solution reveal the
formation of 7. The reaction is quantitative according to the
NMR spectra. Complex 7 has been identified by comparison of
the NMR data.15
Most of the synthetic work was carried out on a Schlenk line or
a nitrogen-filled glove box with oxygen levels below 10 ppm. All
solvents were purified and dried by convential methods and
distilled under argon before use. Benzene-d6 and toluene-d8
were dried by stirring over potassium and then distilled under
vacuum. The silane HSiPh3 and Et3Nؒ3HF were obtained from
Aldrich. [RhH(PEt3)4] (9), [RhF(PEt3)3] (6) and (E)-1,2,3,3,3-
pentafluoropropene (8) were prepared according to the
literature.15,16,24,29
Reaction of [Rh{(Z )-CF᎐CF(CF )}(PEt ) ] (4) with Et Nؒ3HF
᎐
3
3
3
3
A solution of 4 (37 mg, 0.06 mmol) in C6D6 (0.5 mL) was
treated with a solution of Et3Nؒ3HF in THF (10 µL, 0.01
mmol). The 1H, 19F and 31P NMR spectroscopic data reveal the
formation of 6 and (E)-1,2,3,3,3-pentafluoropropene (8).24
The NMR spectra were recorded on a Bruker DRX 500 (1H,
31P and 19F NMR) or a Bruker Avance 600 (1H NMR and 2D
spectra) spectrometer equipped with a triple resonance probe-
1
1
head (13C, H, 19F). The H NMR chemical shifts were refer-
enced to residual C6D5H at δ 7.15 or toluene-d7 at δ 2.1. The
13C{1H} spectra were referenced to C6D6 at δ 128.0. The
31P{1H} NMR spectra are reported downfield of an external
solution of H3PO4 (85%). The 19F NMR spectra were refer-
enced to external C6F6 at δ Ϫ162.9. The infrared spectrum was
recorded on a Bruker IFS-66 spectrometer.
Synthesis of cis-fac-[Rh(H)2(SiPh3)(PEt3)3] (13)
[RhH(PEt3)4] (9) (90 mg, 0.16 mmol) was suspended in hexane
(10 mL), and HSiPh3 (42 mg, 0.16 mmol) was added, giving a
pink solution. The reaction mixture was then stirred for 2 h at
room temperature and the volatiles were removed under vac-
uum. The remaining pink solid was dissolved in hexane (10 mL)
and the solution was filtered through a cannula. Colourless
crystals precipitated at Ϫ35 ЊC. Yield 75.1 mg (71%) (Found: C,
59.53; H, 8.39%. C36H62SiRhP3 requires: C, 59.99; H, 8.66%).
IR [KBr, ν/cmϪ1]: 1972, 2061 (RhH). 1H NMR (toluene-d8, 600
MHz, 198 K): δ 8.16 (m, 6 H, Ph), 7.34 (t, JHH = 7.7 Hz, 6 H,
Ph), 7.23 (t, JHH = 7.6 Hz, 3 H, Ph), 1.70–0.78 (m, 45 H,
CH2CH3), Ϫ10.74 (m, 2 H, RhH). 31P NMR (202.5 MHz, tolu-
ene-d8, 198 K): δ 11.6 (dd, JRhP = 103.3, JPP = 17 Hz, P trans to
H), 4.2 (dt, JRhP = 87.2, JPP = 17 Hz, P trans to Si).
Formation of [Rh{(Z )-CF᎐CF(CF )}(PEt ) ] (4) and
᎐
3
3 3
Et P(F){(Z )-CF᎐CF(CF )} (11)
᎐
3
3
Cs2CO3 (60 mg, 0.18 mmol) was added to a solution of [RhH-
(PEt3)4] (9) (101 mg, 0.18 mmol) and Et3N (26 µL, 0.18 mmol)
in benzene (5 mL). A slow stream of hexafluoropropene (1) was
then passed for 2 min through the reaction mixture. The yellow
suspension was filtered and the solvent was removed from the
filtrate in vacuo yielding a yellow oil. The 31P and 19F NMR
data of the residue reveal the formation of 4 and 11 (ratio ≈
1 : 1). Compounds 4 and 11 were identified by comparison of
the NMR data with the values found in the literature.15,16
Formation of [RhH(PEt3)3] (3) and cis-fac-[Rh(H)2(SiPh3)-
(PEt3)3] (13) from [RhF(PEt3)3] (6)
A solution of 6 (68 mg, 0.14 mmol) in C6D6 (1.5 mL) was
treated with HSiPh3 (48 mg, 0.19 mmol). The 1H and 31P NMR
data of the solution reveal the formation of [RhH(PEt3)3] (3)
and minor amounts (5–10%) of 13. Selected NMR spectro-
scopic data for 3 (see also ref. 29): 1H NMR (600 MHz, toluene-
d8, 198 K): δ Ϫ7.61 (dm, br, JPH = 107.2, Hz, RhH). 31P NMR
Synthesis of [RhF(PEt3)3] (6), (Z )-1,3,3,3-tetrafluoropropene
(10) and [Rh{(E )-C(CF )᎐CHF}(PEt ) ] (12)
᎐
3
3 3
(a) A slow stream of hexafluoropropene (1) was passed for
5 min through a solution of PEt3 (60 µL, 0.40 mmol) in benzene
(3 mL), giving a solution of Et P(F){(Z)-CF᎐CF(CF )} (11). A
᎐
3
3
solution of [RhH(PEt3)4] (9) (202 mg, 0.35 mmol) in benzene
(2 mL) was then added, the reaction mixture was stirred for 1 h
at room temperature, and the volatiles were removed under
vacuum. The remaining brown oil consisted of the complexes
6 and 12 (ratio ≈ 1 : 1), which were characterised by NMR
spectroscopy, as well as of considerable amounts of F2PEt3.18
(b) A slow stream of 1 was passed for 5 min through a
solution of PEt3 (150 µL, 1.02 mmol) in benzene (5 mL). The
solvent was removed under vacuum giving a yellow oil of
(202.4 MHz, toluene-d8, 198 K): δ 25.4 (dd, JRhP = 153.7, JPP
=
29.8 Hz), 21.9 (dt, JRhP = 137.7, JPP = 29.8 Hz, P trans to RhH ).
Synthesis of [Rh{CF᎐CF(CF )}(PEt ) ] (4) from cis-fac-[Rh(H) -
᎐
3
3
3
2
(SiPh3)(PEt3)3] (13)
A slow stream of hexafluoropropene (1) was passed for 3 min
through a solution of 13 (56.9 mg, 0.08 mmol) and NEt3 (40 µL,
0.28 mmol) in benzene (5 mL). The reaction mixture was then
stirred for 1 h at room temperature and the volatiles were
removed under vacuum. The remaining brown oil was
dissolved in benzene (5 mL), and the solution was filtered
through a cannula. Removing the solvent in vacuo gave a yellow
oil. The 19F and 31P NMR data of the solution reveal the
formation of 4 and FSiPh3.15,47 Yield 67 mg (60%).
Et P(F){(Z)-CF᎐CF(CF )} (11). The oil was dissolved in ben-
᎐
3
3
zene (2 mL) and water was added (20 µL, 1.11 mmol). After
distillation under vacuum a solution was obtained containing
(E)-1,2,3,3,3-pentafluoropropene (8). This solution was then
added to a suspension of [RhH(PEt3)4] (9) (24 mg, 0.04 mmol),
Cs2CO3 (50 mg, 0.15 mmol), and Et3N (20 µL, 0.15 mmol) in
benzene (2.5 mL). The reaction mixture was stirred for 1 h
at room temperature and the volatiles were distilled under
vacuum. The distillate consisted of a solution of 10, which was
characterised by NMR spectroscopy.17 The remaining brown oil
consisted of the complexes 6 and 12 (ratio ≈ 1 : 1) as well as
small amounts (≈5%) of 4. Complexes 4 and 6 werde identified
by comparison of the NMR spectroscopic data.15 Selected spec-
Structure determination for complex 13
Colourless crystals of 13 were obtained from a solution in ether
at Ϫ30 ЊC. Diffraction data were collected for a block with
dimensions 0.30 × 0.25 × 0.16 mm on a Nonius Kappa CCD
diffractometer.
Crystal data for 13: C36H62P3RhSi, M = 718.77, monoclinic,
space group P21/c, a = 28.465(3), b = 17.3500(14), c = 22.700(3)
Å, β = 96.928(11)Њ, U = 11129(2) Å3, Z = 12, T = 104(2) K,
µ(Mo-Kα) = 0.645 mmϪ1, 223527 reflections measured, 32417
unique (Rint = 0.0842). The structure was solved by direct
methods (SHELXTL PLUS) and refined with full-matrix least
square methods on F 2 (SHELX-97).48,49 The structure can also
be solved assuming a smaller, but also monoclinic, unit cell
which is one third of the cell used, but the reciprocal lattice
1
troscopic data for 12: H NMR (600 MHz, C6D6): δ 7.27 (dm,
JFH = 77 Hz, ᎐CH), (the resonances for the CH CH group are
᎐
2
3
obscured by similar groups of 6, which is present in the reaction
solution). 31P NMR (202.5 MHz, C6D6): δ 20.4 (Pb trans to
RhC), 17.6 (Pa); for simulation of coupling constants see Fig. 1;
labeling of atoms as in Scheme 2. 19F NMR (470.4 MHz, C6D6):
δ Ϫ69.3 (dm, JFF = 16 Hz, 3 F, CF3), Ϫ118.2 (dddd, JFH = 77,
JPF = 20, JFF = 16, J = 5 Hz, 1 F, ᎐CF).
᎐
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
4081

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11 B. M. Kraft and W. D. Jones, J. Am. Chem. Soc., 2002, 124, 8681.
12 M. S. Kirkham, M. F. Mahon and M. K. Whittlesey, Chem.
Commun., 2001, 813.
shows undoubtedly reflections for the big cell. Using the small
cell yields heavy disordering. Final R1, wR2 values on all data:
0.1171, 0.1139. R1, wR2 values for 18916 reflexions with Io >
2σ(Io): 0.0481, 0.0813.
Hydrogen atoms were fixed at the calculated positions using a
riding model except hydrogens bound at rhodium, which were
refined isotropically. The disordered atoms were also refined
isotropically; ratio in brackets: C20 (72 : 28), C23 and C24
(76 : 24), C26 (77 : 23) and C30 (78 : 22). All other atoms were
refined anisotropically.
13 G. Ferrando-Miguel, H. Gérard, O. Eisenstein and K. G. Caulton,
Inorg. Chem., 2002, 41, 6440; L. A. Watson, D. V. Yandulov and
K. G. Caulton, J. Am. Chem. Soc., 2001, 123, 603; S. A. Strazisar
and P. T. Wolczanski, J. Am. Chem. Soc., 2001, 123, 4728; D. Huang,
J. C. Bollinger, W. E. Streib, K. Folting, V. Young Jr., O. Eisenstein
and K. G. Caulton, Organometallics, 2000, 19, 2281.
14 P. L. Watson, T. H. Tulip and I. Williams, Organometallics, 1990, 9,
1999.
15 T. Braun, D. Noveski, B. Neumann and H.-G. Stammler,
Angew. Chem., 2002, 114, 2870; T. Braun, D. Noveski, B. Neumann
and H.-G. Stammler, Angew. Chem., Int. Ed., 2002, 41, 2745.
16 U. von Allwörden and G.-V. Röschenthaler, Chem.-Ztg., 1988, 112,
69.
CCDC reference number 207704.
See http://www.rsc.org/suppdata/dt/b3/b306635e/ for crystal-
lographic data in CIF or other electronic format.
17 R. N. Haszeldine, D. W. Keen and A. E. Tipping, J. Chem. Soc. C,
1970, 414.
18 K. M. Doxsee, E. M. Hanawalt and T. J. R. Weakley, Inorg. Chem.,
1992, 31, 4420.
19 H. Werner, R. Wiedemann, P. Steinert and J. Wolf, Chem. Eur. J.,
1997, 3, 127.
20 D. W. McBride, E. Dudek and F. G. A. Stone, J. Chem. Soc., 1964,
1752; K. Stanley and D. W. McBride, Can. J. Chem., 1976, 54, 1700.
21 D. J. Burton and S. W. Hansen, J. Am. Chem. Soc., 1986, 108, 4229.
22 P. H. M. Budzelaar, g-NMR, version 4.1, Adept Scientific plc,
Letchworth, 2001.
23 H. C. Clark and W. S. Tsang, J. Am. Chem. Soc., 1969, 89, 533;
M. Akthar and H. C. Clark, Can. J. Chem., 1969, 47, 3753.
24 D. J. Burton, S. Shin-Ya and R. D. Howells, J. Fluorine Chem., 1980,
15, 543; D. J. Burton, T. D. Spawn, P. L. Heinze, A. R. Bailey and
S. Shin-Ya, J. Fluorine Chem., 1989, 44, 167.
Acknowledgements
We would like to acknowledge the Deutsche Forschungs-
gemeinschaft (grants BR 2065/1-3 and BR 2065/1-4), the
“Fonds der Chemischen Industrie” and the University of
Bielefeld for financial support. We are also grateful to Professor
G.-V. Röschenthaler for a gift of hexafluoropropene. T. B.
thanks Professor P. Jutzi for his generous and continuing
support. We appreciate helpful discussions with Dr A. Mix on
the NMR experiments.
References
1 J. Burdeniuc, B. Jedlicka and R. H. Crabtree, Chem. Ber./Recl., 1997,
130, 145; T. G. Richmond, in Topics in Organometallic Chemistry,
ed. S. Murai, Springer, New York, 1999, vol. 3, pp. 243–269; J. L.
Kiplinger, T. G. Richmond and C. E. Osterberg, Chem. Rev., 1994,
94, 373; E. F. Murphy, R. Murugavel and H. W. Roesky, Chem. Rev.,
1997, 97, 3425; U. Mazurek and H. Schwarz, Chem. Commun., 2003,
1321; see also: K. Uneyama and H. Amii, J. Fluorine Chem., 2002,
114, 127.
25 R. N. Haszeldine, C. R. Pool and A. E. Tipping, J. Chem. Soc.,
Perkin Trans. 1, 1974, 2293.
26 R. Fields, M. M. Germain, R. N. Haszeldine and P. W. Wiggans,
J. Chem. Soc. A, 1970, 1969; R. D. Chambers and A. R. Edwards,
J. Chem. Soc., Perkin Trans. 1, 1997, 3623; R. D. Chambers, A. J.
Roche and J. F. S. Vaughan, Can. J. Chem., 1996, 74, 1925; P. L. Coe
and A. G. Holton, J. Fluorine Chem., 1977, 10, 553; R. E. Banks,
W. D. Davies, R. N. Haszeldine and D. R. Taylor, J. Fluorine Chem.,
1977, 10, 487; M. V. Galakhov, V. A. Petrov, V. I. Bakhmutov, G. G.
Belen’kii, B. A. Kvasov, L. S. German and E. I. Fedin, Akad. Nauk
SSR Izv. Ser. Chim., 1995, 306.
27 In this case there are also traces (1–5%) of another product, which
we tentatively assign as mer-[Rh(H)3(PEt3)3]. Evidence for the
proposed structure of this compound will be presented elsewhere; its
full characterisation is in progress.
28 K. Osakada, S. Sarai, T. Koizumi and T. Yamamoto,
Organometallics, 1997, 16, 3973; K. Osakada, T. Koizumi, S. Sarai
and T. Yamamoto, Organometallics, 1998, 17, 1868.
29 T. Yoshida, D. L. Thorn, T. Okano, S. Otsuka and J. A. Ibers, J. Am.
Chem. Soc., 1980, 102, 6451.
30 M. Franz, J. Fluorine Chem., 1980, 15, 423.
31 H. Peterson, J. T. Golden and R. G. Bergman, Organometallics,
1999, 18, 2005.
2 T. Braun and R. N. Perutz, Chem. Commun., 2002, 2749 and
references therein.
3 R. P. Hughes and D. C. Lindner, J. Am. Chem. Soc., 1997, 119,
11544; R. P. Hughes and J. M. Smith, J. Am. Chem. Soc., 1999, 121,
6084; R. P. Hughes, S. Willemsen, A. Williamson and D. Zhang,
Organometallics, 2002, 21, 3085; R. P. Hughes, D. Zhang, L. N.
Zakharov and A. L. Rheingold, Organometallics, 2002, 21, 4902;
T. G. Richmond, Angew. Chem., 2000, 112, 3378; T. G. Richmond,
Angew. Chem., Int. Ed., 2000, 39, 3241.
4 B. L. Edelbach, B. M. Kraft and W. D. Jones, J. Am. Chem. Soc.,
1999, 121, 10327; B. L. Edelbach, A. K. Fazlur-Rahman, R. J.
Lachiocotte and W. D. Jones, Organometallics, 1999, 18, 3170; C. M.
Beck, Y-J. Park and R. H. Crabtree, Chem. Commun., 1998, 693;
T. Braun, S. Rothfeld, V. Schorlemer, A. Stammler and H.-G.
Stammler, Inorg. Chem. Commun., 2003, 6, 752.
5 B. M. Kraft, R. J. Lachicotte and W. D. Jones, J. Am. Chem. Soc.,
2001, 123, 10973.
32 A. R. Siedle and R. A. Newmark, Organometallics, 1989, 8, 1442.
33 C. J. Burns and R. J. Andersen, J. Chem. Soc., Chem. Commun.,
1989, 136; D. Lentz and S. Willemsen, Angew. Chem., 2001, 113,
2142; D. Lentz and S. Willemsen, Angew. Chem., Int. Ed., 2001, 40,
2087; D. Lentz, N. Nickelt and S. Willemsen, Chem. Eur. J., 2002, 8,
1205; M. Fujuwara, J. Ichikawa, T. Okauchi and T. Minami,
Tetrahedron Lett., 1999, 40, 7261.
34 D. L. Thorn and R. L. Harlow, Inorg. Chem., 1990, 29, 2017.
35 B. L. Edelbach and W. D. Jones, J. Am. Chem. Soc., 1997, 119,
7734.
36 R. D. Chambers and J. F. S. Vaughan, in Organofluorine Chemistry:
Fluorinated Alkenes and Reactive Intermediates, ed. R. D. Chambers,
Springer, Berlin, 1997.
37 C. J. Aspley, C. Boxwell, M. L. Buil, C. L. Higgitt, C. Long and
R. N. Perutz, Chem. Commun., 1999, 1027.
38 R. P. Hughes, I. Kovacik, D. C. Lindner, J. M. Smith, S. Willemsen,
D. Zhang, I. A. Guzei and A. L. Rheingold, Organometallics, 2001,
20, 3190.
39 G. Yagupsky, C. K. Brown and G. Wilkinson, Chem. Commun.,
1969, 1244; G. Yagupsky, C. K. Brown and G. Wilkinson, J. Chem.
Soc. A, 1970, 1392.
40 R. Bosque, E. Clot, S. Fantacci, F. Maseras, O. Eisenstein, R. N.
Perutz, K. B. Renkema and K. G. Caulton, J. Am. Chem. Soc., 1998,
120, 12634; S. T. Belt, M. Helliwell, W. D. Jones, M. G. Partridge and
R. N. Perutz, J. Am. Chem. Soc., 1993, 115, 1429; A. D. Selmeczy,
W. D. Jones, M. G. Partridge and R. N. Perutz, Organometallics,
1994, 13, 522.
6 G. B. Deacon, C. M. Forsyth and J. Sun, Tetrahedron Lett., 1994, 35,
1095; Y. Kiso, K. Tamao and M. Kumada, J. Organomet. Chem.,
1973, 50, C12; C. W. K. Gstöttmayr, T. Weskamp and W. A.
Herrmann, Angew. Chem., 2001, 113, 3500; C. W. K. Gstöttmayr,
T. Weskamp and W. A. Herrmann, Angew. Chem., Int. Ed., 2001, 40,
3387; T. Braun, R. N. Perutz and M. I. Sladek, Chem. Commun.,
2001, 2254; D. A. Widdowson and R. Wilhelm, Chem. Commun.,
1999, 2211; R. Wilhelm and D. A. Widdowson, J. Chem. Soc.,
Perkin Trans. 1, 2002, 3808; Y. M. Kam and S. Yu, J. Am. Chem.
Soc., 2003, 125, 1696; F. Mongin, L. Mojovic, B. Giullamet, F.
Trécourt and G. Quéguiner, J. Org. Chem., 2002, 67, 8991; D. A.
Widdowson and R. Wilhelm, Chem. Commun., 2003, 578; Y. Ishii,
N. Chatani, S. Yorimitsu and S. Murai, Chem. Lett., 1998, 157.
7 R. J. Young and V. V. Grushin, Organometallics, 1999, 18, 294;
H. Yang, H. Gao and R. J. Angelici, Organometallics, 1999, 18,
2285; C. Desmarets, S. Kuhl, R. Schneider and Y. Fort,
Organometallics, 2002, 21, 1554; N. Y. Adonin and V. F. Starichenko,
Mendeleev Commun., 2000, 60; J. L. Kiplinger and T. G. Richmond,
J. Am. Chem. Soc., 1996, 118, 1805; S. Kuhl, R. Schneider and
Y. Fort, Adv. Synth. Catal., 2003, 345, 341.
8 M. Aizenberg and D. Milstein, J. Am. Chem. Soc., 1995, 117,
8674.
9 M. Aizenberg and D. Milstein, Science, 1994, 265, 359.
10 B. M. Kraft, R. J. Lachicotte and W. D. Jones, J. Am. Chem. Soc.,
2000, 122, 8559.
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
4082

View Article Online
41 H. Gérard and O. Eisenstein, J. Chem. Soc., Dalton Trans., 2003,
839.
K. G. Caulton, Angew. Chem., Int. Ed., 1997, 36, 2004; D. Huang
and K. G. Caulton, J. Am. Chem. Soc., 1997, 119, 3185; J. E.
Veltheer, P. Burger and R. G. Bergman, J. Am. Chem. Soc., 1995,
117, 12478.
42 R. N. Haszeldine, J. R. McAllister and A. E. Tipping, J. Chem. Soc.,
Perkin Trans. 1, 1975, 2015; I. P. Belentskaya, G. A. Artamkina,
A. Y. Mil’chenko, P. K. Sazonov and M. M. Shtern, J. Phys. Org.
Chem., 1996, 9, 319.
46 T. Hiyama, Organofluorine Compounds, Springer, Berlin, 2000, p.
196; A. R. Ravishankara, A. A. Turnipseed, N. R. Jensen, S. Barone,
M. Mills, C. J. Howard and S. Solomon, Science, 1994, 263, 71.
47 P. D. Lickiss and R. Lucas, J. Organomet. Chem., 1996, 510, 167.
48 SHELXTL-PLUS, Siemens Analytical X-Ray Instruments Inc.,
Madison, WI, USA, 1990.
43 N. Ojima, Chem. Rev., 1988, 88, 1011.
44 C. G. Krespan, in Chemistry of Organic Fluorine Compounds II, ed.
M. Hudlicky and E. E. Pavlath, ACS, Washington DC, 1995,
pp. 297–320.
45 D. Huang, W. E. Streib, O. Eisenstein and K. G. Caulton, Angew.
Chem., 1997, 109, 2096; D. Huang, W. E. Streib, O. Eisenstein and
49 G. M. Sheldrick, SHELX-97, program for crystal structure
refinement, University of Göttingen, 1997.
D a l t o n T r a n s . , 2 0 0 3 , 4 0 7 5 – 4 0 8 3
4083