Synthesis of a rhodium(i) germyl complex: A useful tool for C-H and C-F bond activation reactions

Article abstract of DOI:10.1039/c5dt04845a

The dihydrido germyl complex cis,fac-[Rh(GePh₃)(H)₂(PEt₃)₃] (2) was synthesized by an oxidative addition of HGePh₃ at [Rh(H)(PEt₃)₃] (1). Treatment of 2 with neohexene generated the rhodium(i) germyl complex [Rh(GePh₃)(PEt₃)₃] (3). Alternatively, treatment of the methyl complex [Rh(CH₃)(PEt₃)₃] (4) with HGePh₃ furnished at room temperature also 3. Low-temperature NMR measurements revealed an initial formation of the oxidative addition product fac-[Rh(GePh₃)(H)(CH₃)(PEt₃)₃] (5), which transforms into the intermediate complex [Rh(GePh₃)(H)(CH₃)(PEt₃)₂] (6) by dissociation of a triethylphosphine ligand. The reductive elimination of methane and coordination of PEt₃ afforded the germyl complex 3. Treatment of 3 with CO gave the biscarbonyl complex [Rh(GePh₃)(CO)₂(PEt₃)₂] (7). The molecular structures of the complexes 2, 3 and 7 were determined by X-ray crystallography. The germyl complex 3 reacted with 2,3,5,6-tetrafluoropyridine or pentafluorobenzene to furnish the C-H activation products [Rh(4-C₅NF₄)(PEt₃)₃] (8) and [Rh(C₆F₅)(PEt₃)₃] (9), respectively. The reaction of 3 with hexafluorobenzene or perfluorotoluene gave selectively the C-F activation products 9 and [Rh(4-C₆F₄CF₃)(PEt₃)₃] (10). Treatment of 3 with pentafluoropyridine resulted in the formation of the C-F activation products 8 and [Rh(2-C₅NF₄)(PEt₃)₃] (11) in a 1 : 10 ratio. The two isomeric activation compounds [Rh{(E)-CF=CF(CF₃)}(PEt₃)₃] (12) and [Rh{(Z)-CF=CF(CF₃)}(PEt₃)₃] (13) were obtained in a 3 : 1 ratio by reaction of 3 with hexafluoropropene. On exposure to oxygen the highly air sensitive complex 12 reacts to yield the peroxido-bridged dirhodium complex [Rh{(E)-CF=CF(CF₃)}(μ-κ¹:η²-O₂)(PEt₃)₂]₂ (14). The molecular structure of 14 was determined by X-ray crystallography.

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Synthesis of a rhodium(I) germyl complex: a useful
tool for C–H and C–F bond activation reactions†‡
Cite this: DOI: 10.1039/c5dt04845a
Theresia Ahrens, Mike Ahrens, Thomas Braun,* Beatrice Braun and Roy Herrmann
The dihydrido germyl complex cis,fac-[Rh(GePh3)(H)2(PEt3)3] (2) was synthesized by an oxidative addition
of HGePh3 at [Rh(H)(PEt3)3] (1). Treatment of 2 with neohexene generated the rhodium(I) germyl complex
[Rh(GePh3)(PEt3)3] (3). Alternatively, treatment of the methyl complex [Rh(CH3)(PEt3)3] (4) with HGePh3
furnished at room temperature also 3. Low-temperature NMR measurements revealed an initial formation
of the oxidative addition product fac-[Rh(GePh3)(H)(CH3)(PEt3)3] (5), which transforms into the intermedi-
ate complex [Rh(GePh3)(H)(CH3)(PEt3)2] (6) by dissociation of a triethylphosphine ligand. The reductive
elimination of methane and coordination of PEt3 afforded the germyl complex 3. Treatment of 3 with CO
gave the biscarbonyl complex [Rh(GePh3)(CO)2(PEt3)2] (7). The molecular structures of the complexes 2, 3
and 7 were determined by X-ray crystallography. The germyl complex 3 reacted with 2,3,5,6-tetrafluoro-
pyridine or pentafluorobenzene to furnish the C–H activation products [Rh(4-C5NF4)(PEt3)3] (8) and
[Rh(C6F5)(PEt3)3] (9), respectively. The reaction of 3 with hexafluorobenzene or perfluorotoluene gave
selectively the C–F activation products
9 and [Rh(4-C6F4CF3)(PEt3)3] (10). Treatment of 3 with
pentafluoropyridine resulted in the formation of the C–F activation products 8 and [Rh(2-C5NF4)(PEt3)3]
(11) in a 1 : 10 ratio. The two isomeric activation compounds [Rh{(E)-CFvCF(CF3)}(PEt3)3] (12) and [Rh{(Z)-
CFvCF(CF3)}(PEt3)3] (13) were obtained in a 3 : 1 ratio by reaction of 3 with hexafluoropropene. On
exposure to oxygen the highly air sensitive complex 12 reacts to yield the peroxido-bridged dirhodium
complex [Rh{(E)-CFvCF(CF3)}(µ–κ1:η2-O2)(PEt3)2]2 (14). The molecular structure of 14 was determined by
X-ray crystallography.
Received 11th December 2015,
Accepted 2nd February 2016
DOI: 10.1039/c5dt04845a
www.rsc.org/dalton
usually the formation of another strong bond like a H–F, Si–F,
B–F, Al–F or even a M–F bond.23,79 C–F activation reactions for
Introduction
In the past few decades the interest in fluorinated molecules which a strong germanium–fluorine bond is formed are rare
as building blocks has increased drastically due to their appli- and have not been reported for transition-metal mediated reac-
cations in agrochemicals, pharmaceuticals and advanced tions.80 At rhodium, Milstein et al. demonstrated that the
materials.1–6 The activation of C–F bonds mediated by tran- rhodium(I) silyl complexes [Rh(SiR3)(PMe3)3] (SiR3 = SiMe2Ph,
sition-metal complexes is meanwhile a fairly well established SiPh3) react with hexafluorobenzene to afford the fluoroaryl
research area.7–25 The selective C–F bond cleavage in highly complex [Rh(C6F5)(PMe3)3] and the corresponding fluoro-
fluorinated or perfluorinated molecules can represent
a
silanes.81 Furthermore, a catalytic conversion of hexafluoro-
unique way to access fluorinated building blocks. Thus, in the benzene into pentafluorobenzene was achieved by using [Rh(H)-
coordination sphere of a metal complex new fluorinated mole- (PMe3)4] as catalyst.82 Later it was shown that [Rh(H)(PEt3)3] (1)
cules can be formed, which are otherwise not accessible or is also suitable to activate pentafluoropyridine as well as hexa-
difficult to access.7–65 Note that transition-metal mediated fluoropropene by a selective C–F bond cleavage.83–85 The latter
fluorination reactions provide an alternative way to synthesize reaction resulted in the formation of the (Z)-C–F activation
fluorinated compounds.66–78 The thermodynamic driving force product [Rh{(Z)-CFvCF(CF3)}(PEt3)3] (13) which catalyses
for C–F bond activation reactions at transition-metal centers is in the presence of hydrosilanes the selective formation of
3,3,3-trifluoropropylsilane from hexafluoropropene.52
Herein we report on the synthesis of a unique 16-electron
Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor-Straße 2,
rhodium(I) germyl complex [Rh(GePh3)(PEt3)3] (3) and its reac-
tivity towards small molecules like CO and H2. Furthermore,
D-12489 Berlin, Germany. E-mail: thomas.braun@chemie.hu-berlin.de
†Dedicated to Prof. Erhard Kemnitz on the occasion of his 65th birthday.
reactivity studies concerning C–H and C–F bond activation
‡Electronic supplementary information (ESI) available. CCDC 1438402–1438406.
reactions of highly fluorinated pyridines, aromatics and hexa-
For ESI and crystallographic data in CIF or other electronic format see DOI:
fluoropropene are described.
10.1039/c5dt04845a
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simulation of the 1H NMR spectrum (Fig. 1).88 The pattern
indicates a large phosphorus–hydrogen coupling constant
Results and discussion
Treatment of the hydrido complex [Rh(H)(PEt3)3] (1) with which is typical for
HGePh3 led to the formation of the oxidative addition product position.52,54,84,89–91 In the H{31P} decoupling experiment the
cis,fac-[Rh(GePh3)(H)2(PEt3)3] (2) (Scheme 1). signal simplified to a doublet due to the coupling to the
a phosphine ligand in the trans-
1
The 31P{1H} NMR spectrum of the rhodium(III) complex 2 rhodium atom (Fig. 1, top). The IR spectrum of 2 displays two
shows the expected splitting pattern. A doublet of triplets at absorption bands at ˜ν = 2025 and 1968 cm−1 which are
δ = 15.5 ppm (1JRh,P = 100 Hz) for the phosphine ligand in the assigned to the RhH2 vibrations and the data are comparable
trans-position to the germyl ligand and a doublet of doublets to those of known rhodium dihydrido complexes.52,84 In
at δ = 11.1 ppm (1JRh,P = 96 Hz) for the phosphine ligands in addition DFT calculations support also the presence of two
the trans-position to the hydrido ligands. The values for the absorption bands (see ESI‡). The Rh(I) complex [Rh(acac)-
phosphorus–rhodium coupling constants are characteristic for (GeEt3)(H)(PCy3)] (˜ν = 2060 cm−1, acac = acetylacetonate) or
a RhIII species.86,87 The 1H NMR spectrum reveals for both [Rh(Cl)(H)(GeR3)(PPh3)2] (R = Me, Et; ˜ν = 2107–2035 cm−1
)
hydrido ligands a resonance signal at δ = −11.3 ppm which is show absorption bands which are shifted towards higher
of higher order. The coupling constants were determined by wavenumbers.92–94 The molecular structure of 2 in the solid
state was determined by X-ray crystallography (Fig. 2). Light
yellow crystals were obtained from a toluene/n-hexane solution
at 243 K. Selected bond lengths and angles are summarized in
Table 1. Note that the asymmetric unit contains three crystallo-
graphically independent molecules which show only minor
differences in bond lengths and angles. Therefore, only one
will be discussed and is shown as an ORTEP diagram (Fig. 2).
Scheme 1 Synthesis of the rhodium(I) germyl complex [Rh(GePh3)-
(PEt3)3] (3).
Fig. 2 An ORTEP diagram of 2. Ellipsoids are drawn at the 50% prob-
ability level. C–H hydrogen atoms were omitted for clarity. The
rhodium-bound hydrogen atoms were located in the difference Fourier
map and refined isotropically.
Table 1 Selected bond lengths [Å] and angles [°] in cis,fac-[Rh(GePh3)
(H)2(PEt3)3] (2)
Lengths [Å]
P1–Rh1
P2–Rh1
P3–Rh1
2.3738(5)
2.3718(6)
2.3430(5)
Ge1–Rh1
H1–Rh1
H2–Rh1
2.4502(5)
1.56(3)
1.51(3)
Angles [°]
P1–Rh1–P2
P1–Rh1–P3
P2–Rh1–P3
P1–Rh1–Ge1
P2–Rh1–Ge1
P3–Rh1–Ge1
P1–Rh1–H1
P2–Rh1–H1
104.393(15)
104.013(18)
104.459(16)
96.338(13)
97.932(13)
144.633(13)
172.2(10)
P3–Rh1–H1
Ge1–Rh1–H1
Ge1–Rh1–H2
P1–Rh1–H2
P2–Rh1–H2
P3–Rh1–H2
H1–Rh1–H2
80.1(10)
76.9(10)
72.1(9)
83.8(9)
168.0(9)
81.6(9)
90.3(14)
Fig. 1 Part of the 1H NMR spectrum of complex 2; simulated (bottom)
observed (middle) and part of the 1H{31P} NMR spectrum (top) using the fol-
lowing coupling constants (Hz): 1J(Rh,Pa) = 1J(Rh,Pa’) = 100.6, 1J(Rh,Pb) =
95.7, 2J(Pa,Pb) = 2J(Pa’,Pb) = 22.1, 2J(Pa,Pa’) = 20.3,1 J(Rh,Hx) = 1J(Rh,Hx’) =
13.7, 2J(Pa,Hx) = 2J(Pa’,Hx’) = 133.7, 2J(Pa’,Hx) = 2J(Pa,Hx’) = −21.1, 2J(Pb,
Hx) = 2J(Pb,Hx’) = 16.8, 2J(Hx,Hx’) = 4.8.
80.7(10)
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The molecular structure of 2 reveals a distorted octahedral
coordination geometry at the metal center where the three
phosphine ligands occupy the facial positions. Both metal
bound hydrogen atoms were located in the difference Fourier
map and refined isotropically. The two hydrido ligands are
located in a mutually cis-position to each other. The P–Rh–P
angles and the Ge–Rh–P angels are all larger than 90° indicat-
ing the slight distortion. The rhodium–phosphorus bond
length of 2.3430(5) Å in the trans-position to the Ge atom is
noticeably shorter than the other two rhodium–phosphorus
bond lengths [2.3738(5) and 2.3718(6) Å]. When compared to
the corresponding distances found in the structural related
silyl complexes cis,fac-[Rh(H)2(SiClPh2)(PMe3)3] [Rh–P trans to
Si = 2.334(2) Å], cis,fac-[Rh(H)2{SiPh2(SPh)}(PMe3)3] [Rh–P trans
to Si = 2.336(1) Å] and cis,fac-[Rh(H)2{Si(C6H4CF3)3}(PMe3)3]
[Rh–P trans to Si = 2.326(4) Å], The Rh–P bond length is in a
similar range which might imply a comparable trans influence
of the germyl ligand as the silyl ligand.84,95–97 The Rh(1)–Ge(1)
bond length of 2.4502(5) Å is shorter than the distance in carbo-
nyl complexes like [Rh(GePh3)(CO)4] [Rh–Ge = 2.5061(4) Å].98
The reaction of [Rh(GePh3)(H)2(PEt3)3] (2) with neohexene
resulted in the formation of the 16 electron rhodium(I) germyl
complex [Rh(GePh3)(PEt3)3] (3, Scheme 1). Note that the oxi-
dative addition of H2 at 3 affords again the dihydrido complex
2. The 31P{1H} NMR spectrum of 3 depicts a doublet of doub-
Table 2 Selected bond lengths [Å] and angles [°] in [Rh(GePh3)(PEt3)3] (3)
Lengths [Å]
P1–Rh1
P2–Rh1
2.2822(4)
2.3162(4)
P3–Rh1
Ge1–Rh1
2.3268(4)
2.46459(18)
Angles [°]
P1–Rh1–P2
P1–Rh1–P3
P2–Rh1–P3
95.987(13)
149.509(14)
93.191(13)
P1–Rh1–Ge1
P2–Rh1–Ge1
P3–Rh1–Ge1
91.634(10)
154.276(11)
92.558(10)
same range like these in the structural related silyl complexes
[Rh(SiPh3)(PMe3)3] and [Rh(SiMe2Ph)(PMe3)3] [2.266(1)–
2.332(1) Å].89,90 The formation of 3 from [Rh(CH3)(PEt3)3] (4)
and HGePh3 was also monitored by low temperature NMR
spectroscopy. The studies reveal the initial generation of the
oxidative addition product fac-[Rh(GePh3)(H)(CH3)(PEt3)3] (5)
at 203 K (Scheme 2). The latter converts into [Rh(GePh3)(H)-
(CH3)(PEt3)2] (6) at 213 K by phosphine dissociation. The reduc-
tive elimination of methane affords the 16 electron rhodium(I)
germyl complex [Rh(GePh3)(PEt3)3] (3). The reaction is inhibited
by free phosphine indicating that the reductive elimination of
methane does not occur from 5, but from complex 6.
The 31P{1H} NMR spectrum of 5 displays three doublets of
triplets at δ = 13.1, 9.4 and 5.7 ppm (Fig. 4).102 The rhodium–
phosphorus coupling constants (1JRh,P = 93–87 Hz) and the
phosphorus–phosphorus coupling constants (2JP,P ≈ 22 Hz) are
compatible with the assignment as a RhIII complex.86,87 The
observed pattern is in accordance with a fac-configuration for 5.
The 1H NMR spectrum of 5 shows a broad signal at δ =
0.16 ppm which can be assigned to the methyl group. The
2
lets at δ = 11.1 ppm (1JRh,P = 143, JP,P = 36 Hz) for the phos-
phine ligand in a mutually trans-position and a doublet of
2
triplets at δ = 6.5 ppm (1JRh,P = 136, JP,P = 36 Hz). The
rhodium–phosphorus coupling constants indicate the pres-
ence of a Rh(I) species.56,91,99–101 The molecular structure of 3
in the solid state was determined by X-ray crystallography
(Fig. 3). Selected bond lengths and angles are summarized in
Table 2. Suitable crystals of 3 were grown from a saturated n-
hexane solution at 243 K. The structure exhibits a distorted
square-planar coordination geometry at the metal center. The
Rh(1)–Ge(1) distance [2.46459(18) Å] is in a similar range to
those found for complex 2. The Rh–P distances [2.2822(4)–
2.3268(4) Å] are – when compared to 2 – shorter, but in the
resonance signal for the hydrido ligand appears as a doublet of
1
doublets of triplets at δ = −10.69 ppm (2JH,P-cis = 20 Hz, JH,Rh
≈
2JH,P-cis ≈ 11 Hz) revealing a large phosphorus–hydrogen coup-
ling of 157 Hz to a phosphine ligand at the trans-position
(Fig. 5). In a 31P decoupling experiment the signal simplified
1
to a doublet confirming the JH,Rh coupling constant. An
additional 1H,31P HMBC NMR spectrum, which was optimized
to a large H,P coupling constant, reveals a correlation peak for
Fig. 3 An ORTEP diagram of 3. Ellipsoids are drawn at the 50% prob-
ability level. C–H hydrogen atoms were omitted for clarity.
Scheme 2 Reaction pathway for the formation of [Rh(GePh3)(PEt3)3] (3).
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Fig. 6 DFT-optimized structure with the lowest energy of Rh(GePh3)-
(H)(CH3)(PEt3)2] (6). The hydrogen atoms at the aromatic rings and phos-
phine ligands are omitted for clarity.
Fig. 4 Part of the 31P{1H} NMR spectrum of the reaction solution after
treatment of 4 with HGePh3 at 203 K (below) and 213 K (above).
found that the energy differences in the gas phase are small
and four minima converged at close energy. Their geometry
differs in the ligand that occupies the apical position
(H ligand or CH3 ligand) as well as in the orientation of the
ethyl groups at the phosphine ligands. However, the computed
structure with the lowest energy shows a distorted square pyra-
midal coordination arrangement (τ = 0.14)103 at the central
metal atom with the hydrido ligand in the apical position and
both phosphine ligands in a mutually trans-position. The opti-
mized geometry is in good accordance with the obtained NMR
data as well as a presumable syn elimination of methane.
Treatment of 3 with CO afforded the biscarbonyl complex
[Rh(GePh3)(CO)2(PEt3)2] (7) by replacement of one phosphine
ligand (Scheme 3). The 31P{1H} NMR spectrum for 7 shows at
δ = 13.7 ppm a doublet (1JRh,P = 111 Hz) for both phosphine
ligands. Due to a fluxional behavior of 7 in solution only one
signal was observed, which did not split into two resonances
at low temperature (203 K). A doublet of triplets (1JRh,C = 65,
2JC,P = 1 Hz) in the 13C NMR spectrum at δ = 201.3 ppm can be
attributed to the CO ligands. The values for the rhodium–
carbon and rhodium–phosphorus coupling constants are in a
typical range for rhodium carbonyl complexes bearing two
phosphine ligands.85,90,104 The IR spectrum of 7 exhibits two
absorption bands at ˜ν = 1964 and 1912 cm−1 which can be
assigned to the Rh(CO)2 unit. The structural related germyl
complex [Rh(GeEt3)(CO)2(PPh3)2] or silyl complex [Rh{Si(OEt)3}-
(CO)2(PMe3)2] show similar values.90,93,94
Fig. 5 Part of the 1H NMR spectrum (below, 300 MHz) and part of the
1H{31P} NMR spectrum (above, 400 MHz) of 5 and 6 at 213 K.
the hydrido ligand and the phosphine ligands in a mutually
trans-position at δH/P = −10/13 ppm which appears as a
doublet (2JH,P-trans = 157 Hz) in the 1H domain. By warming the
reaction solution up to 213 K the 31P{1H} NMR spectrum
reveals an additional doublet at δ = 19.3 ppm with a rhodium–
phosphorus coupling constant of 115 Hz which can be
assigned to the intermediate rhodium complex [Rh(GePh3)(H)-
(CH3)(PEt3)2] (6). A resonance for the formation of free phos-
1
phine was also observed. The H NMR spectrum of 6 shows a
singlet at δ = 0.26 ppm for the methyl group. Furthermore a
second signal at δ = −11.53 ppm appears which simplifies to a
doublet (1JH,Rh = 15 Hz) on 31P decoupling and can be
assigned to the hydrido ligand. Again a 1H,31P HMBC NMR
spectrum which was optimized on a small phosphorus–hydro-
gen coupling constant confirms the structure of 6 by showing
a cross peak at δH/P = −11/19 ppm. No large hydrido–phos-
phorus coupling was observed indicating a cis-arrangement of
both phosphine ligands to the hydrido ligand. To get more
information on the structure of 6, DFT calculations were run
on conceivable isomers and the optimized geometry with the
Suitable crystals for an X-ray diffraction analysis of 7 were
obtained from a saturated toluene/n-hexane solution at 243 K.
lowest energy (6a) is depicted in Fig. 6 (see also ESI‡). It was Scheme 3 Formation of the rhodium(I) biscarbonyl complex 7.
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Table 3 Selected bond lengths [Å] and angles [°] in [Rh(GePh3)-
(CO)2(PEt3)2] (7)
Lengths [Å]
Rh1–P1
Rh1–P2
Rh1–Ge1
2.3448(4)
2.4123(4)
2.4840(19)
1.8817(15)
Rh1–C31
O1–C31
O2–C32
1.8841(15)
1.1478(19)
1.1476(19)
Rh1–C32
Angles [°]
P1–Rh1–P2
P1–Rh1–Ge1
P2–Rh1–Ge1
C32–Rh1–C3
C32–Rh1–P1
103.082(14)
160.307(11)
96.587(11)
134.95(7)
C31–Rh1–P1
C32–Rh1–P2
C31–Rh1–P2
Rh1–C31–O1
Rh1–C32–O2
89.11(5)
111.17(5)
113.10(5)
175.49(14)
175.94(15)
88.88(5)
Selected bond lengths and angles are summarized in Table 3.
The coordination geometry of the molecular structure of 7 can
be considered as either distorted square pyramidal or a dis-
torted trigonal bipyramidal coordination arrangement at the
central metal atom (Fig. 7). The parameter τ for complex 7
(0.42) indicates that a description as a square pyramidal struc-
ture is more appropriate, for which the phosphine ligand in
the cis-position to the germyl ligand occupies the apical posi-
tion.103 The Rh–P bond lengths [2.3448(4) Å; 2.4123(4) Å] and
the Rh–C bond lengths with [1.8817(15) Å; 1.8841(15) Å] are in
a typical range. Both rhodium carbonyl units are not linear
with a Rh–C–O angle of 175.49(14) and 175.94(15)°. The Rh(1)–
Ge(1) distance of 2.4840(19) Å is comparable to these found
for the complexes 2 and 3.
Scheme 4 C–H activation of 2,3,5,6-tetrafluoropyridine and pen-
tafluorobenzene at [Rh(GePh3)(PEt3)3] (3).
[Rh(H)(PEt3)3] (1) or the boryl complex [Rh(Bpin)(PEt3)3] (pin =
pinacolato) with 2,3,5,6-tetrafluoropyridine to give also 8.56,85
Marder and Perutz reported that the rhodium silyl complex
[Rh(SiPh3)(PMe3)3] is capable of both C–F (2-position) and
C–H (4-position) bond activation.51 It was also reported that
the silyl complexes [Rh{Si(OR)3}(PEt3)3] (R = Me, Et) react by
C–F bond activation.91,105
Complex 3 also reacted with an excess of hexafluorobenzene
at 323 K to yield the C–F activation product 9 (Scheme 5). The
reaction of 3 with perfluorotoluene at 323 K afforded [Rh(4-
C6F4CF3)(PEt3)3] (10) with the CF3 group at the para-position.
Additional free phosphine does not lead to a decrease of the
reaction rate indicating that an initial phosphine dissociation
does not play a role prior to the C–F activation step. Treatment
of 3 with pentafluoropyridine resulted in a C–F bond activation
at the 2- and 4-position to yield the activation products [Rh(4-
C5NF4)(PEt3)3] (8) and [Rh(2-C5NF4)(PEt3)3] (11) in a 1 : 10 ratio.
The activation at the 2-position may occur by a concerted oxi-
dative addition process.106–111 An alternative pathway involves
a ligand-assisted C–F activation step.19,20,23,54,56,65,91,112–116 The
highly reactive rhodium boryl complex [Rh(Bpin)(PEt3)3] and
the silyl complex [Rh{Si(OR)3}(PEt3)3] (R = Me, Et) also furn-
ished the C–F activation products 8, 9, 10 and 11 by treatment
with the fluorinated pyridine or the aromatic com-
pounds.56,91,117 The mechanisms for the activation at the
4-position that are commonly discussed in the literature are
often linked to a radical pathway or an initial nucleophilic
attack of the metal center.10,118–120 Note that Roesky and Stalke
reported on the C–F activation of pentafluoropyridine at the
4-position at the germylene LGeNiPr2 [L = PhC(NtBu)2], but in
contrast this conversion proceeds via an oxidative addition.80
Treatment of the germyl complex [Rh(GePh3)(PEt3)3] (3) with
hexafluoropropene in n-hexane led to the formation of the C–F
activation product [Rh{(E)-CFvCF(CF3)}(PEt3)3] (12) and the
isomeric complex [Rh{(Z)-CFvCF(CF3)}(PEt3)3] (13) in a 3 : 1
ratio as well as of FGePh3 after 8 h (Scheme 6). The ratio and
C–H and C–F bond activation reactions
Reactivity studies of the germyl complex [Rh(GePh3)(PEt3)3] (3)
towards fluorinated pyridines and aromatics as substrates
might be of interest concerning C–F and C–H bond activation
reactions.23,25 The treatment of 3 with pentafluorobenzene or
2,3,5,6-tetrafluoropyridine afforded the C–H activation pro-
ducts [Rh(4-C5NF4)(PEt3)3] (8) and [Rh(C6F5)(PEt3)3] (9),
respectively, as well as HGePh3 (Scheme 4). There is no evi-
dence for a C–F bond cleavage. Note that similar C–H bond
activations were observed on treatment of the hydrido complex
Fig. 7 An ORTEP diagram of 7. Ellipsoids are drawn at the 50% prob-
ability level. C–H hydrogen atoms were omitted for clarity.
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Scheme 5 C–F activation of fluorinated aromatics and pentafluoropyridine at [Rh(GePh3)(PEt3)3].
reaction time are solvent dependent. If the reaction is carried mation of a dinuclear peroxido-bridged rhodium complex
out in benzene a full conversion was achieved after 2 h with a [Rh{(E)-CFvCF(CF3)(µ–κ1:η2-O2)(PEt3)2]2 (14), which exhibits a
ratio of 12 : 1 for 12 to 13. The formation of complex 13 has rare coordination mode of the O2 units (Scheme 7), as well as
been described before.83,84 Thus, the hydrido complex [Rh(H)- OPEt3. The formation of the isomeric compound [Rh{(Z)-
(PEt3)3] (1) reacts with hexafluoropropene in the presence of CFvCF(CF3)}(µ–κ1:η2-O2)(PEt3)2]2 was not observed pre-
Et3N and Cs2CO3 to yield 13. The 31P{1H} and 19F NMR spectra sumably due to decomposition reactions.
of 12 are of higher order. Therefore the 31P{1H} NMR spectrum
was computed in order to determine the coupling constants,
and the result is depicted in Fig. 8.88 The 19F NMR spectrum
reveals three resonances at δ = −64.4 (CF3), −78.1 (Fα) and
−148.0 (Fβ) ppm in a 3 : 1 : 1 ratio that can be assigned to the
propenyl ligand. In contrast to 13 no large fluorine–fluorine
coupling constant was observed, which indicates a cis-arrange-
ment of the olefinic fluorine atoms.121 The 19F,13C{1H} HMBC
NMR spectrum reveals cross-peaks at δF/C = −64/123 (CF3),
−78/190 (Fα–Cα) and −148/140 (Fβ–Cβ) ppm which supports the
structural assignment for 12.84 The reaction of an in situ gene-
rated mixture of 12 and 13 with dioxygen led to the instant for-
Scheme 6 C–F activation of hexafluoropropene at the rhodium(I)
germyl complex 3.
Scheme 7 Selective oxygenation reaction of the C–F activation
product 12.
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Table 4 Selected distances [Å] and angles [°] in [Rh{(E)-CFvCF(CF3)}
(µ–κ1:η2-O2)(PEt3)2]2 (14a)
Lengths [Å]
Rh1–O1
2.1542(12)
2.0954(12)
1.9988(13)
2.2900(5)
2.3411(5)
1.9999(19)
1.4702(17)
2.6578(18)
O2–O2i
3.5561(17)
2.7737(18)
1.331(3)
1.400(2)
1.372(2)
1.9436(13)
2.3598(13)
Rh1i–O1
O1–O2i
Rh1–O2
Rh1–P1
Rh1–P2
Rh1–C13
C13–C14
C13–F1
C14–F2
Rh1–Omiddle
O1–O2
Rh1i–Omiddle
O1–O1i
Angles [°]
O1–Rh1–P1
O1–Rh1–P2
O2–Rh1–P1
O2–Rh1–P2
P2–Rh1–P1
O2–Rh1–O1
O1–Rh1–O1i
O2–Rh1–O1i
O1i–Rh1–P1
O1i–Rh1–P2
90.15(3)
119.91(4)
81.20(4)
160.71(4)
106.315(18)
41.25(5)
77.42(5)
85.26(5)
166.07(4)
85.59(4)
O2–O1–Rh1
O2i–O1i–Rh1
O2–Rh1–C13
C13–Rh1–O1
C13–Rh1–O1i
C13–Rh1–P1
C13–Rh1–P2
Rh1–O1–Rh1i
O1–O2–Rh1
63.70(7)
101.94(8)
109.93(6)
150.90(6)
99.79(6)
87.99(5)
88.36(5)
102.58(5)
75.05(7)
Fig. 8 Part of the 31P{1H} NMR spectrum of complex 12; simulated
(below) observed (above) using the following coupling constants (Hz):
1J(Rh,Pa) = 145.3, 1J(Rh,Pb) = 120.3 2J(Pa,Pb) = 39.3, 3J(Pa,Fα) = 4.7, 4J(Pa,
Fβ) = 6.7, 5J(Pa,F) = 0.8, 3J(Pb,Fα) = 24.4, 4J(Pb,Fβ) = 10.6, 5J(Pb,F) = 1.5.
crystals (block) of 14a were obtained from a toluene/n-hexane
solution at 243 K. Selected bond lengths and angles are sum-
marized in Table 4. In the solid state complex [Rh{(E)-CFvCF
(CF3)}(µ–κ1:η2-O2)(PEt3)2]2 (14a) adopts a binuclear coordi-
nation mode in which two peroxido ligands bridge two
rhodium centers via one oxygen atom of the peroxido units.
The geometry around the rhodium centers can be either
described as approximately trigonal-bipyramidal, if the per-
oxido unit is treated as occupying a single coordination site or
as a distorted octahedral structure if it is regarded as a biden-
tate ligand. The latter seems to be more appropriate and is con-
sistent with the oxidation state III at the rhodium center which
was suggested by the obtained NMR data. The Rh(1)–O(1) and
Rh(1)–O(2) bond lengths with 2.1542 (12) Å and 1.9988(13) Å
differ noticeably from each other resulting in an asymmetrical
bridging whereas the oxygen atom with the longer Rh–O bond
length exhibits a shorter distance to the other metal center [Rh-
(1i)–O(1) = 2.0954(12) Å]. The O(1)–O(2) separation of 1.4702(17)
Å is consistent with the distances found for other rhodium η2-
peroxido complexes.99,100,122,128–133 The values for the Rh–C,
CvC as well as the C–F bond lengths of the pentafluoropropenyl
ligand are comparable to these found for complex 13.83 For late
transition-metal complexes the rhodium complexes [Rh(µ–κ1:η2-
O2)(PhBP3)]2 [PhBP3 = tris(methylenediphenylphosphane)phenyl-
borate] and [Rh(Cl)(µ–κ1:η2-O2)(PPh3)2]2 as well as the palladium
complex [{Pd(κ2-TpiPr)}2(µ–κ1:η2-O2)(py)] [TpiPr = hydridotris(3,5-
diisopropylpyrazolyl)-borato] are the only three precedents
reported in the literature which exhibit such an unusual µ–κ1:η2-
O2-bridging mode.134–137
Note that in comparable reactions usually the formation of
mononuclear peroxido complexes was observed.99,100,122,123
The 31P{1H} NMR spectrum of 14 shows a doublet of doublets
at δ = 26.4 ppm due to the coupling to the rhodium atom
(1JRh,P = 121 Hz) and to the fluorine atom (3JP,F = 29 Hz) at the
α-carbon atom of the pentafluoropropenyl ligand. The
rhodium-phosphorus coupling constant is in a typical range
for a binuclear Rh(III) spezies.124–127 The 19F NMR spectrum
depicts three resonances at δ = −65.5 (CF3), −66.5 (Fα) and
−143.6 (Fβ) ppm in a 6 : 2 : 2 ratio for the propenyl ligand. The
chemical shifts are in a similar range than those found for 12
or 13.83,84 Two polymorphic structures of 14 (14a and 14b) in
the solid state were determined by X-ray crystallography (Fig. 9
for 14a and ESI‡ for 14b). Due to the structural similarities
only the data for 14a are discussed in the following. Yellow
Conclusions
In this paper we report on the synthesis of the 16 electron
rhodium(I) germyl complex [Rh(GePh3)(PEt3)3] (3) and its reac-
tivity towards highly fluorinated substrates. The studies
Fig. 9 An ORTEP diagram of 14a. Ellipsoids are drawn at the 50% prob-
ability level. C–H hydrogen atoms were omitted for clarity.
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revealed that the germyl complex 3 is a useful tool for C–F solid precipitated. The solvent was filtered of and the residue
bond activation reactions which extend the range of suitable was dried in vacuo to obtain 2 as a pale yellow solid. Yield
rhodium(I) complexes in this field. It was found that the for- 137 mg (90%). Analytical data for 2: C36H62GeP3Rh (764.34):
mation of 3, reacting [Rh(CH3)(PEt3)3] (3) with HGePh3, was calcd C, 56.64; H, 8.19; found: C, 56.87; H, 8.21. IR (ATR)
initiated via a PEt3 dissociation at fac-[Rh(GePh3)(H)(CH3)- ˜ν (cm−1): 2025, 1968 (RhH2). 1H NMR (500.1 MHz, [D8]thf): δ =
(PEt3)3] (5) and recoordination. For the preferred formation of 7.59 (m, dd in the 1H{31P} NMR spectrum, 3J(H,H) = 8, 4J(H,H)
1
the C–F activation product [Rh(2-C5NF4)(PEt3)3] (11) a ligand- = 2 Hz, 6H; Ph), 7.07–6.99 (m, 9H; Ph), 1.80 (m, q in the H
3
assisted process is conceivable, which involves an interaction {31P} NMR spectrum J(H,H) = 8 Hz, 6H; PCH2CH3), 1.50 (m,
of the germyl ligand with a fluorine atom. This conversion q in the 1H{31P} NMR spectrum 3J(H,H) = 8 Hz, 12H; PCH2CH3),
3
3
extends the range of C–F activation reactions at rhodium(I) 1.17 (dt, J(H,P) = 13, J(H,H) = 8 Hz, 9H; PCH2CH3), 0.87 (dt,
3
1
complexes such as [Rh(H)(PEt3)3], [Rh(Bpin)(PEt3)3], [Rh(Bcat)- 3J(H,P) = 14, J(H,H) = 8 Hz, 18H; PCH2CH3), −11.28 (m, J(Rh,
(PEt3)3], [Rh(SiPh3)(PMe3)3] or [Rh{Si(OEt)3}(PEt3)3].56,81,85,91,117 Pa) = J(Rh,Pa′) = 100.6, J(Rh,Pb) = 95.7, J(Pa,Pb) = J(Pa′,Pb) =
1
1
2
2
The treatment of the germyl complex 3 with hexafluoropropene 22.1, J(Pa,Pa′) = 20.3, J(Rh,Hx) = J(Rh,Hx′) = 13.7, J(Pa,Hx) =
2
1
1
2
led to a new C–F activation product [Rh{(E)-CFvCF(CF3)}- 2J(Pa′,Hx′) = 133.7, 2J(Pa′,Hx) = 2J(Pa,Hx′) = −21.1, 2J(Pb,Hx) =
(PEt3)3] (12) as a major product. Exposure of 12 to an oxygen 2J(Pb,Hx′) = 16.8, J(Hx,Hx′) = 4.8 Hz, 2H; RhH) ppm. The coup-
2
atmosphere gave the dinuclear peroxido-bridged rhodium ling constants were determined by simulation with gNMR.88
complex [Rh{(E)-CFvCF(CF3)(µ–κ1:η2-O2)(PEt3)2]2 (14) which 31P{1H} NMR (121.5 MHz, [D6]benzene): δ = 15.5 (dt, J(Rh,P) =
1
exhibits a rare coordination mode of the O2 moiety.
100, 2J(P,P) = 20 Hz, 1P), 11.1 (dd, 1J(Rh,P) = 96, 2J(P,P) = 20 Hz,
2P) ppm. MS (LIFDI, toluene), m/z: 764 [M]+.
Synthesis of [Rh(GePh3)(PEt3)3] (3). (a)
A solution of
[Rh(GePh3)(H)2(PEt3)3] (2) (118 mg, 0.15 mmol) in benzene
(2 mL) was treated with neohexene (50 µL, 0.38 mmol). The
reaction mixture was stirred for 2 h at room temperature. All
Experimental
General methods and instrumentations
The synthetic work was carried out with a Schlenk line or in a volatiles were removed in vacuo and a dark red solid remained.
glove box under an atmosphere of argon. All solvents were Yield 113 mg (99%).
purified and dried by conventional methods and distilled
(b) A solution of [Rh(CH3)(PEt3)3] (3) (153 mg, 0.32 mmol)
under an atmosphere of argon before use. [D6]Benzene, [D8]thf in n-hexane (4 mL) was treated with a solution of HGePh3
and [D8]toluene were dried by stirring over Na/K and then dis- (98 mg, 0.32 mmol) in n-hexane (1 mL). The reaction mixture
tilled. Triphenylgermane was obtained from ABCR and used was stirred for 30 min at room temperature. All volatiles were
without further purification. [Rh(H)(PEt3)3] (1) and [Rh(CH3)- removed in vacuo. A dark red solid was obtained. Yield 242 mg
(PEt3)3] (4) were prepared according to the literature.87,138,139 (98%). Analytical data for 3: C36H60P3GeRh (761.32): calcd C,
1
The NMR spectra were acquired on a Bruker DPX 300, Bruker 56.79; H, 7.94; found: C, 56.68; H, 7.95. H NMR (300.1 MHz,
Avance 300 or Bruker Avance 400 spectrometer. The 1H and [D6]benzene): δ = 8.10 (m, 6H; Ph), 7.20 (m, 6H; Ph), 7.18 (m,
13C NMR chemical shifts were referenced to residual [D5] 3H; Ph), 1.66–1.40 (m, 18H; PCH2CH3), 1.20–0.76 (m, 27H;
benzene at δ = 7.15 ppm, [D7]thf at δ = 1.73 ppm or [D7]toluene PCH2CH3) ppm. 31P{1H} NMR (121.5 MHz, [D6]benzene) δ = 11.1
1
2
1
at δ = 2.09 ppm. The 19F NMR spectra were referenced to exter- (dd, J(Rh,P) = 143, J(P,P) = 36 Hz, 2P), 6.5 (dt, J(Rh,P) = 136,
nal CFCl3 at δ = 0.0 ppm. The 31P{1H} NMR spectra were refer- 2J(P,P) = 36 Hz, 1P) ppm. MS (LIFDI, toluene), m/z: 762 [M]+.
enced externally to 85% H3PO4 at δ = 0.0 ppm. Infrared spectra
Formation of fac-[Rh(GePh3)(H)(CH3)(PEt3)3] (5). A solution
were recorded on a Bruker Vertex 70 spectrometer that was of HGePh3 (20 mg, 65 µmol) in [D8]toluene (0.1 mL) was
equipped with an ATR unit (diamond). Mass spectrometry was added to a solution of [Rh(CH3)(PEt3)3] (4) (31 mg, 65 µmol) in
measured with a Micromass Q-TOF-2 mass spectrometer [D8]toluene (0.4 mL) at 183 K. The NMR spectroscopic data of
which was equipped with a Linden LIFDI source (Linden CMS the reaction solution at 203 K revealed a complete conversion
GmbH). Microanalyses were performed with a HEKAtech Euro of 4 into 5. Analytical data for 5: 1H NMR (300.1 MHz, [D8]-
3
EA 3000 elemental analyzer.
toluene, 203 K) δ = 8.19 (d, J(H,H) = 7 Hz, 6H, Ph), 7.32 (m,
Synthesis of [Rh(GePh3)(H)2(PEt3)3] (2). (a) A solution of 6H; Ph), 7.22 (m 3H;Ph), 1.63 (m, 6H; PCH2CH3), 1.47 (m, 9H;
HGePh3 (113 mg, 0.37 mmol) in n-hexane (2 mL) was added to PCH2CH3), 1.00–0.60 (m, 30H; PCH2CH3), 0.16 (br s, 3H; CH3),
a solution of [Rh(H)(PEt3)3] (1) (170 mg, 0.37 mmol) in −10.69 (ddt, d in the 1H{31P} NMR spectrum, 2J(H,Ptrans) = 157,
n-hexane (4 mL). The reaction mixture turned from dark red to 2J(H,Pcis) = 20, 1J(H,Rh) = 11, 2J(H,Pcis) = 12 Hz, 1H; RhH)
pale yellow within seconds. After stirring for 30 min the reac- ppm. 31P{1H} NMR (121.5 MHz, [D8]toluene, 203 K) δ = 13.1
tion mixture was filtered. The residue was washed twice with (dt, 1J(Rh,P) = 93, 2J(P,P) = 21 Hz, 1P; P trans to H), 9.4 (dt,
n-hexane (3 mL) and dried in vacuo to obtain 2 as a pale yellow 1J(Rh,P) = 87, 2J(P,P) = 22 Hz, 1P), 5.7 (dt, 1J(Rh,P) = 91,
solid. Yield 257 mg (89%).
2J(P,P) = 22 Hz, 1P) ppm. 1H,31P HMBC NMR (400.1 MHz/
(b) A slow stream of hydrogen was bubbled through a solu- 161.9 MHz, [D8]toluene, 203 K) δ = −10.6/13 (d in the 1H
tion of [Rh(GePh3)(PEt3)3] (3) (153 mg, 0.20 mmol) in n-hexane domain, 2J(H,P) = 157 Hz; RhH) ppm.
(5 mL) for 2 min at room temperature. The solution turned
Formation of [Rh(GePh3)(H)(CH3)(PEt3)2] (6). (a) A solution
from dark red to yellow. After stirring for 30 min a pale yellow of fac-[Rh(GePh3)(H)(CH3)(PEt3)3] (5) (65 µmol) in [D8]toluene
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(0.5 mL) was generated in situ by treatment of [Rh(CH3)(PEt3)3] NMR tube. After 36 h at 323 K the quantitative formation of 10
(4) (31 mg, 65 µmol) with HGePh3 (20 mg, 65 µmol) at 203 K and FGePh3 was observed by NMR spectroscopy. Complex 10
and was allowed to warm up to 213 K. The NMR spectroscopic and FGePh3 were identified by comparison of their NMR data
data of the reaction solution revealed after 30 min the inter- with the literature.91,140
mediate formation of [Rh(GePh3)(H)(CH3)(PEt3)2] (6) along
Formation of [Rh(2-C5NF4)(PEt3)3] (11) and [Rh(4-C5NF4)-
with [Rh(GePh3)(PEt3)3] (3), free PEt3 and unreacted 5 in a ratio (PEt3)3] (8). Pentafluoropyridine (2.5 μL, 0.023 mmol) was
1 : 8 : 1 : 16. Selected NMR data for 6: 1H NMR (300.1 MHz, added to a solution of [Rh(GePh3)(PEt3)3] (3) (17.9 mg,
[D8]toluene, 213 K): δ = 0.26 (br s, 3H; CH3), −11.53 (dt, d in 0.023 mmol) in [D6]benzene (0.5 mL). After 23 h the quantitat-
the 1H{31P} NMR spectrum 1J(H,Rh) = 15, 2J(H,Pcis) = 16 Hz; ive formation of 11 and 8 in a 10 : 1 ratio as well as the for-
RhH) ppm. The signals for the ethyl and phenyl groups in 6 mation of FGePh3 was observed by NMR spectroscopy.
are covered by resonances of [Rh(GePh3)(PEt3)3] (3) and fac- Complex 11, 8 and FGePh3 were identified by comparison of
[Rh(GePh3)(H)(CH3)(PEt3)3] (5). 31P{1H} NMR (121.5 MHz, their NMR data with the literature.56,85,140
[D8]toluene, 213 K): δ = 19.3 (d, 1J(Rh,P) = 115 Hz) ppm. 1H,31P
HMBC NMR (400.1 MHz/161.9 MHz, [D8]toluene, 203 K): δ = CFvCF(CF3)}(PEt3)3] (13). A slow stream of hexafluoropropene
−11/19 (s; RhH) ppm. was bubbled for 30 s through a solution of [Rh(GePh3)(PEt3)3]
Formation of [Rh{(E)-CFvCF(CF3)}(PEt3)3] (12) and [Rh{(Z)-
Synthesis of [Rh(GePh3)(CO)2(PEt3)2] (7). A slow stream of (3) (30 mg, 0.039 mmol) in n-hexane (3 mL) in a PFA tube.
CO was passed for 1 min through a solution of [Rh(GePh3)- After stirring for 8 h at room temperature all volatiles were
(PEt3)3] (3) (68 mg, 89 µmol) in benzene (2 mL) at room temp- removed in vacuo. The NMR spectroscopic data of the residue
erature. The solution turned from dark red to yellow. After stir- reveal the formation of 12 and 13 in a 3 : 1 ratio as well as the
ring for 30 min all volatiles were removed in vacuo. The residue formation of FGePh3 and some unidentified fluorine contain-
was washed once with n-hexane (1 mL) and 7 was obtained as ing species. Complex 13 and FGePh3 were identified by com-
a yellow solid. Yield 58 mg (93%). Analytical data for 7: parison of the NMR data with the literature.83,140 Selected
C32H45GeO2P2Rh (701.20): calcd C, 54.97; H, 6.49; found: C, NMR data for 12: 19F NMR (282.4 MHz, [D6]benzene): δ =
55.07; H, 6.49. IR (ATR) ˜ν (cm−1): 1964, 1912 (CO). 1H NMR −64.4 (m, 3F; CF3), −78.1 (m, 1F; Fα), −148.0 (m, 1F; Fβ) ppm.
(300.1 MHz, [D6]benzene): δ = 8.02 (m, 6H; Ph), 7.28 (m, 6H; 31P{1H} NMR (121.5 MHz, [D6]benzene): δ = 18.4 (dddtm,
2
3
4
Ph), 7.20–7.13 (m, 3H; Ph), 1.28 (m, q in the 1H{31P} NMR 1J(Rh,Pb) = 120.3, J(Pa,Pb) = 39.3, J(Pb,Fα) = 24.4, J(Pb,Fβ) =
spectrum J(H,H) = 8 Hz, 12H; PCH2CH3), 0.81 (dt, 3J(H,P) = 10.6, 1P; Pb), 11.6 (ddddm, J(Rh,Pa) = 145.3, J(Pa,Pb) = 39.3,
3
1
2
15, 3J(H,H) = 8 Hz, 18H; PCH2CH3) ppm. 13C{1H} NMR 3J(Pa,Fα) = 6.7, J(Pa,Fβ) = 4.7, J(Pa,F) = 0.8, 2P; Pa) ppm. The
4
5
1
2
(75.5 MHz, [D8]thf): δ = 202.4 (dt, J(C,Rh) = 65, J(C,P) = 1 Hz, coupling constants were determined by simulation with
CO), 148.4 (s; Ph), 136.8 (s; Ph), 128.1 (s; Ph) 128.0 (s; Ph), 21.2 gNMR.88 19F,13C{1H} HMBC NMR (282.4 MHz/75.4 MHz,
(m, 1J(C,P) = 11 Hz; PCH2CH3), 8.5 (s; PCH2CH3) ppm, the [D6]benzene) δ = −64/123 (dm, J(C,F) = 267 Hz; CF3), −78/190
1
assignment of the signals is supported by a 1H,13C HMBC NMR (dm, J(C,F) = 323 Hz; Cα–Fα), −148.0/140 ppm (dm, J(C,F) =
1
1
spectrum. 31P{1H} NMR (121.5 MHz, [D6]benzene): δ = 13.7 (d, 231 Hz; Cβ–Fβ).
1J(Rh,P) = 111 Hz) ppm. MS (LIFDI, toluene), m/z: 700 [M]+.
Synthesis
Formation [Rh(4-C5NF4)(PEt3)3] (8). 2,3,5,6-Tetrafluoropyri- (14). A slow stream of hexafluoropropene was bubbled for 30 s
dine (2 μL, 0.020 mmol) was added to a solution of [Rh(GePh3)- through solution of [Rh(GePh3)(PEt3)3] (3) (153 mg,
of
[Rh{(E)-CFvCF(CF3)}(µ–κ1:η2-O2)(PEt3)2]2
a
(PEt3)3] (3) (15 mg, 0.020 mmol) in [D6]benzene (0.5 mL). After 0.17 mmol) in toluene (7 mL) in a PFA tube. After stirring for
16 h the quantitative formation of 8 and HGePh3 was observed 12 h at room temperature all volatiles were removed in vacuo.
by NMR spectroscopy. Complex 8 was identified by compari-
The quantitative formation of [Rh{(E)-CFvCF(CF3)}(PEt3)3]
(12) and [Rh{(Z)-CFvCF(CF3)}(PEt3)3] (13) in a 6 : 1 ratio as
son of its NMR data with the literature.85
Formation of [Rh(C6F5)(PEt3)3] (9). (a) Hexafluorobenzene well as the formation of FGePh3 was observed by NMR spectro-
(0.2 mL) was added to a solution of [Rh(GePh3)(PEt3)3] scopy. The residue was dissolved in benzene (5 ml) and a slow
(18.2 mg, 0.024 mmol) in n-hexane (0.2 mL) in a PFA NMR stream of oxygen was bubbled for 30 s through the reaction
tube. After 5 d at 323 K the quantitative formation of 9 and mixture at 223 K. The solution was allowed to warm up slowly
FGePh3 was observed by NMR spectroscopy. Complex 9 and to room temperature. After stirring for 20 min all volatiles were
FGePh3 were identified by comparison of their NMR data with removed in vacuo. The residue was washed twice with n-hexane
the literature.91,140
(2 mL) and 14 was obtained as a yellow solid after crystalliza-
(b) Pentafluorobenzene (2 μL, 0.018 mmol) was added to a tion of a statured toluene/n-hexane solution at 243 K. Yield
solution of [Rh(GePh3)(PEt3)3] (3) (14 mg, 0.018 mmol) in 21 mg (25%). Analytical data for 14: C30H60F10O4P4Rh2
1
[D6]benzene (0.5 mL). After 36 h the quantitative formation of (1004.48): calcd C, 35.87; H, 6.02; found: C, 36.15; H, 5.75. H
9 and HGePh3 was observed by NMR spectroscopy. Complex 9 NMR (300.1 MHz, [D6]benzene): δ = 1.93 (m, 12H; PCH2CH3),
1
was identified by comparison of its NMR data with the 1.71 (m, 12H; PCH2CH3) 1.01 (m, t in the H{31P} NMR spec-
literature.91
trum 3J(H,H) Hz, 36H; PCH2CH3) ppm. 19F NMR
= 8
3
4
Formation [Rh(4-C6F4CF3)(PEt3)3] (10). Octafluorotoluene (282.4 MHz, [D6]benzene): δ = −65.5 (dd, J(F,Fβ) = 16, J(F,Fα)
(3 μL, 0.021 mmol) was added to a solution of [Rh(GePh3)- = 8 Hz, 6F; CF3), −66.5 (dm, J(Fα,P) = 29 Hz, 2F; Fα), −143.6
3
(PEt3)3] (16 mg, 0.021 mmol) in [D8]toluene (0.4 mL) in a PFA (qm, J(Fβ,F) = 16 Hz, 2F; Fβ) ppm. 31P{1H} NMR (121.5 MHz,
4
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Table 5 Crystallographic data
2
3
7
14a
14b
Crystal dimensions [mm3]
Crystal color
Empirical formula
M
0.50 × 0.36 × 0.34
Yellow
C36H62GeP3Rh
763.26
0.40 × 0.35 × 0.30
Red
C36H60GeP3Rh
761.25
0.46 × 0.16 × 0.10
Yellow
C32H45GeO2P2Rh
699.12
0.14 × 0.13 × 0.12
Light yellow
C30H60F10O4P4Rh2
1004.48
0.31 × 0.07 × 0.01
Light yellow
C30H60F10O4P4Rh2
1004.48
Crystal system
Space group
a [Å]
b [Å]
c [Å]
Monoclinic
P21/c
Monoclinic
P21/c
Monoclinic
P21/c
Monoclinic
P21/n
Monoclinic
P21/n
28.273(5)
17.334(3)
23.140(4)
97.339(6)
11 248.0(4)
12
1.352
1.393
2.32 to 39.68
498 870
74 954
11.5439(2)
22.2499(5)
18.1297(3)
127.1720(10)
3710.51(12)
4
1.363
1.410
2.21 to 28.34
66 019
9140
17.9962(4)
10.8071(2)
18.7150(4)
116.882(2)
3246.50(12)
4
1.430
1.559
4.58 to 28.40
44 424
7419
11.5052(14)
11.7794(12)
15.3559(17)
92.700(5)
2078.8(4)
2
1.605
1.024
2.27 to 25.37
18 889
3810
10.3168(5)
18.2065(9)
11.2497(6)
95.380(2)
2103.75(18)
2
1.586
1.012
1.56 to 25.04
29 343
3730
β [°]
V [Å3]
Z
Dcalcd. [mg m−3
]
μ(Mo-Kα) [mm−1
θ range [°]
]
Reflns. collected
Indep. reflns.
Rint
0.0876
99.7
Multi-scan
0.996
0.0653
99.7
Multi-scan
0.985
0.0458
99.5
Multi-scan
1.018
0.0331
99.6
Multi-scan
1.008
0.0488
99.5
Multi-scan
1.063
Completeness [%]
Absorption correction
GoF on F2
R1, wR2 on all data
R1, wR2[I0 > 2σ(I0)]
Max. diff. peak/hole [e Å−3
0.1140, 0.0960
0.0526, 0.0814
2.609/−1.255
0.0298, 0.0464
0.0214, 0.0449
0.474/−1.083
0.0255, 0.0500
0.0205, 0.0489
0.475/−0.912
0.0235, 0.0588
0.0211, 0.0571
0.672/−0.577
0.0334, 0.0549
0.232, 0.0517
0.557/−0.488
]
[D6]benzene): δ = 26.4 (dd, 1J(Rh,P) = 121, 3J(P,F) = 29 Hz) except for germanium, which was described on using RECPs
ppm. MS (LIFDI, toluene), m/z: 1004 [M]+.
with the associated cc-pVTZ-PP basis set.147 Rhodium was also
described on using RECPs with the associated cc-pVTZ-PP
basis set.148 Frequency calculations were run for all stationary
points to identify them as minima (no negative eigenvalues).
Energies were corrected for zero-point energy.
Structure determination
Suitable crystals of 2, 7 and 14a/b were obtained from satu-
rated toluene/n-hexane solutions at 243 K. Dark red crystals of
3 were obtained by slow evaporation of the solvent from a
n-hexane solution at 243 K. Data collections for 2, 14a and 14b
were performed at 100 K with a Bruker D8 Venture area detec-
tor and on a STOE IPDS 2θ for 3 and 7.
Acknowledgements
We would like to acknowledge for financial support the DFG
The structures were solved by intrinsic phasing (2, 14a and
14b) and by direct methods (3 and 7) (SHELXS-2013) and
refined by full matrix least-squares procedures based on F2
with all measured reflections (SHELXL-2013).141–143 The
SADABS program was used for multi-scan absorption correc-
tions for 2, 14a and 14b and PLATON was used for multi-scan
absorption correction of 3 and 7.144,145 All non-hydrogen
atoms were refined anisotropically. All hydrogen atom posi-
tions were placed at their idealized positions and were refined
using a riding model except for the rhodium bound hydrogen
atoms in 2, which were found on the electron density map and
freely refined. CCDC 1438402 (for 2), 1438403 (for 3), 1438404
(for 7), 1438405 (for 14a) and 1438406 (for 14b) contain the
crystallographic data (Table 5).
research training group “Fluorine as
a Key Element”
(T. Ahrens) as well as the DFG (BR-2065/8-2). M. Ahrens thanks
the “Fonds der Chemischen Industrie”. We thank the Solvay
Fluor GmbH for a gift of hexafluoropropene. We are grateful to
Dipl.-Chem. Cathérine Mitzenheim and Dr. Lada Zámostná for
help with the NMR spectroscopy. We would like to thank Silke
Hinze for experimental assistance.
References
1 R. E. Banks, Fluorine Chemistry at the Millennium: Fasci-
nated by Fluorine, Elsevier, Amsterdam, 2000.
2 T. Hiyama, Organofluorine Compounds: Chemistry and
Applications, Springer, Berlin, 2000.
3 P. Kirsch, Modern Fluoroorganic Chemistry: Synthesis, Reac-
tivity and Applications, Wiley-VCH, Weinheim, 2004.
4 J. A. Gladysz, D. P. Curran and I. T. Horvath, Handbook of
Fluorous Chemistry, Wiley-VCH, Weinheim, 2006.
5 J. P. Bégué and D. Bonnet-Delpon, Bioorganic and Medi-
cinal Chemistry of Fluorine, John Wiley & Sons, Inc.,
Hoboken, New York, 2008.
Computational methods
The calculations were run using the Gaussian 09 (Revision
D.01) program package146 and the B3LYP functional. Plausible
ligand arrangements for [Rh(GePh3)(H)(CH3)(PEt3)2] were opti-
mized and the structure 6a turned out to be the minimum.
The cc-pVTZ basis sets were employed for all rhodium-bound
atoms (cc-pVDZ for all other carbon and hydrogen atoms)
Dalton Trans.
This journal is © The Royal Society of Chemistry 2016

View Article Online
Dalton Transactions
Paper
6 P. Kirsch, Modern Fluoroorganic Chemistry: Synthesis, Reac-
tivity, Applications, Wiley-VCH, Weinheim, 2013.
7 J. L. Kiplinger, T. G. Richmond and C. E. Osterberg, Chem.
Rev., 1994, 94, 373–431.
8 J. Burdeniuc, B. Jedlicka and R. H. Crabtree, Chem. Ber.,
1997, 130, 145–154.
9 T. G. Richmond, Angew. Chem., Int. Ed., 2000, 39, 3241–
3244, (Angew. Chem., 2000, 112, 3378–3380).
10 T. Braun and R. N. Perutz, Chem. Commun., 2002, 2749–
2757.
11 H. Torrens, Coord. Chem. Rev., 2005, 249, 1957–1985.
12 R. N. Perutz and T. Braun, in Comprehensive Organometal-
lic Chemistry III, ed. D. M. P. Mingos and R. H. Crabtree,
Elsevier, Oxford, 2007, pp. 725–758.
34 U. Jager-Fiedler, M. Klahn, P. Arndt, W. Baumann,
A. Spannenberg, V. V. Burlakov and U. Rosenthal, J. Mol.
Catal. A: Chem., 2007, 261, 184–189.
35 R. D. Rieth, W. W. Brennessel and W. D. Jones,
Eur. J. Inorg. Chem., 2007, 2839–2847.
36 S. P. Reade, M. F. Mahon and M. K. Whittlesey, J. Am.
Chem. Soc., 2009, 131, 1847–1861.
37 B. M. Kraft, E. Clot, O. Eisenstein, W. W. Brennessel and
W. D. Jones, J. Fluorine Chem., 2010, 131, 1122–1132.
38 M. F. Kuhnel and D. Lentz, Angew. Chem., Int. Ed., 2010,
49, 2933–2936, (Angew. Chem., 2010, 122, 2995–2998).
39 J. A. Panetier, S. A. Macgregor and M. K. Whittlesey,
Angew. Chem., Int. Ed., 2011, 50, 2783–2786, (Angew.
Chem., 2011, 123, 2835–2838).
13 S. A. Macgregor, Chem. Soc. Rev., 2007, 36, 67–76.
14 R. N. Perutz, Science, 2008, 321, 1168–1169.
15 H. Amii and K. Uneyama, Chem. Rev., 2009, 109, 2119–
2183.
16 G. Meier and T. Braun, Angew. Chem., Int. Ed., 2009, 48,
1546–1548, (Angew. Chem., 2009, 121, 1575–1577).
17 R. P. Hughes, Eur. J. Inorg. Chem., 2009, 4591–4606.
18 A. D. Sun and J. A. Love, Dalton Trans., 2010, 39, 10362–
10374.
40 M. F. Kuehnel, P. Holstein, M. Kliche, J. Kruger,
S. Matthies, D. Nitsch, J. Schutt, M. Sparenberg and
D. Lentz, Chem. – Eur. J., 2012, 18, 10701–10714.
41 M. F. Kuehnel, T. Schloder, S. Riedel, B. Nieto-Ortega,
F. J. Ramirez, J. T. L. Navarrete, J. Casado and D. Lentz,
Angew. Chem., Int. Ed., 2012, 51, 2218–2220, (Angew.
Chem., 2012, 124, 2261–2263).
42 L. Zámostná, M. Ahrens and T. Braun, J. Fluorine Chem.,
2013, 155, 132–142.
19 E. Clot, O. Eisenstein, N. Jasim, S. A. Macgregor,
J. E. McGrady and R. N. Perutz, Acc. Chem. Res., 2011, 44,
333–348.
20 T. Braun and F. Wehmeier, Eur. J. Inorg. Chem., 2011, 613–
625.
43 S. A. Macgregor, D. McKay, J. A. Panetier and
M. K. Whittlesey, Dalton Trans., 2013, 42, 7386–7395.
44 Y. Ishii, N. Chatani, S. Yorimitsu and S. Murai, Chem.
Lett., 1998, 157–158.
45 T. Braun, S. P. Foxon, R. N. Perutz and P. H. Walton,
Angew. Chem., Int. Ed., 1999, 38, 3326–3329, (Angew.
Chem., 1999, 111, 3543–3545).
21 A. Nova, R. Mas-Balleste and A. Lledos, Organometallics,
2012, 31, 1245–1256.
22 M. Klahn and U. Rosenthal, Organometallics, 2012, 31,
1235–1244.
46 M. I. Sladek, T. Braun, B. Neumann and H. G. Stammler,
J. Chem. Soc., Dalton Trans., 2002, 297–299.
23 M. F. Kuehnel, D. Lentz and T. Braun, Angew. Chem., Int.
Ed., 2013, 52, 3328–3348, (Angew. Chem., 2013, 125, 3412–
3433).
47 T. Braun, S. Rothfeld, V. Schorlemer, A. Stammler and
H. G. Stammler, Inorg. Chem. Commun., 2003, 6, 752–
755.
24 J. Weaver and S. Senaweera, Tetrahedron, 2014, 70, 7413–
7428.
25 T. Ahrens, J. Kohlmann, M. Ahrens and T. Braun, Chem.
Rev., 2015, 115, 931–972.
26 B. L. Edelbach, A. K. F. Rahman, R. J. Lachicotte and
W. D. Jones, Organometallics, 1999, 18, 3170–3177.
27 B. M. Kraft, R. J. Lachicotte and W. D. Jones, J. Am. Chem.
Soc., 2000, 122, 8559–8560.
28 B. M. Kraft, R. J. Lachicotte and W. D. Jones, J. Am. Chem.
Soc., 2001, 123, 10973–10979.
29 B. M. Kraft and W. D. Jones, J. Organomet. Chem., 2002,
658, 132–140.
30 B. M. Kraft and W. D. Jones, J. Am. Chem. Soc., 2002, 124,
8681–8689.
31 E. Clot, C. Megret, B. M. Kraft, O. Eisenstein and
W. D. Jones, J. Am. Chem. Soc., 2004, 126, 5647–5653.
32 J. Vela, J. M. Smith, Y. Yu, N. A. Ketterer,
C. J. Flaschenriem, R. J. Lachicotte and P. L. Holland,
J. Am. Chem. Soc., 2005, 127, 7857–7870.
48 T. Braun, A. Steffen, V. Schorlemer, B. Neumann and
H. G. Stammler, Dalton Trans., 2005, 3331–3336.
49 T. Braun, J. Izundu, A. Steffen, B. Neumann and
H.-G. Stammler, Dalton Trans., 2006, 5118–5123.
50 T. Braun, V. Schorlemer, B. Neumann and
H. G. Stammler, J. Fluorine Chem., 2006, 127, 367–372.
51 R. J. Lindup, T. B. Marder, R. N. Perutz and
A. C. Whitwood, Chem. Commun., 2007, 3664–3666.
52 T. Braun, F. Wehmeier and K. Altenhoener, Angew. Chem.,
Int. Ed., 2007, 46, 5321–5324, (Angew. Chem., 2007, 119,
5415–5418).
53 M. Arisawa, T. Suzuki, T. Ishikawa and M. Yamaguchi,
J. Am. Chem. Soc., 2008, 130, 12214–12215.
54 T. Braun, M. A. Salomon, K. Altenhoner, M. Teltewskoi
and S. Hinze, Angew. Chem., Int. Ed., 2009, 48, 1818–1822,
(Angew. Chem., 2009, 121, 1850–1854).
55 H. L. Buckley, T. Wang, O. Tran and J. A. Love, Organo-
metallics, 2009, 28, 2356–2359.
56 M. Teltewskoi, J. A. Panetier, S. A. Macgregor and
T. Braun, Angew. Chem., Int. Ed., 2010, 49, 3947–3951,
(Angew. Chem., 2010, 122, 4039–4043).
33 A. A. Peterson and K. McNeill, Organometallics, 2006, 25,
4938–4940.
This journal is © The Royal Society of Chemistry 2016
Dalton Trans.

View Article Online
Paper
Dalton Transactions
57 L. Keyes, A. D. Sun and J. A. Love, Eur. J. Org. Chem., 2011,
3985–3994.
58 J.-H. Zhan, H. Lv, Y. Yu and J.-L. Zhang, Adv. Synth. Catal.,
2012, 354, 1529–1541.
59 H. Lv, J.-H. Zhan, Y.-B. Cai, Y. Yu, B. Wang and
J.-L. Zhang, J. Am. Chem. Soc., 2012, 134, 16216–16227.
60 L. Sun, M. Rong, D. Kong, Z. Bai, Y. Yuan and Z. Weng,
J. Fluorine Chem., 2013, 150, 117–123.
61 H. Lv, Y.-B. Cai and J.-L. Zhang, Angew. Chem., Int. Ed.,
2013, 52, 3203–3207, (Angew. Chem., 2013, 125, 3285–
3289).
83 T. Braun, D. Noveski, B. Neumann and H. G. Stammler,
Angew. Chem., Int. Ed., 2002, 41, 2745–2748, (Angew.
Chem., 2002, 114, 2870–2873).
84 D. Noveski, T. Braun, M. Schulte, B. Neumann and
H. G. Stammler, Dalton Trans., 2003, 4075–4083.
85 D. Noveski, T. Braun, B. Neumann, A. Stammler and
H. G. Stammler, Dalton Trans., 2004, 4106–4119.
86 A. Vigalok, L. J. W. Shimon and D. Milstein, Chem.
Commun., 1996, 1673–1674.
87 T. Braun, D. Noveski, M. Ahijado and F. Wehmeier, Dalton
Trans., 2007, 3820–3825.
62 T. Ichitsuka, T. Fujita, T. Arita and J. Ichikawa, Angew.
Chem., Int. Ed., 2014, 53, 7564–7568, (Angew. Chem., 2014,
162, 7694–7698).
63 H. Zhang, J.-H. Lin, J.-C. Xiao and Y.-C. Gu, Org. Biomol.
Chem., 2014, 12, 581–588.
64 A. Singh, J. J. Kubik and J. D. Weaver, Chem. Sci., 2015, 6,
7206–7212.
65 W.-H. Guo, Q.-Q. Min, J.-W. Gu and X. Zhang, Angew.
Chem., Int. Ed., 2015, 54, 9075–9078, (Angew. Chem., 2015,
127, 9203–9206).
66 V. V. Grushin, Chem. – Eur. J., 2002, 8, 1006–1014.
67 C. Bobbio and V. Gouverneur, Org. Biomol. Chem., 2006, 4,
2065–2075.
68 J. M. Brown and V. Gouverneur, Angew. Chem., Int. Ed.,
2009, 48, 8610–8614, (Angew. Chem., 2009, 121, 8762–
8766).
88 P. H. M. Budzelaar, gNMR, Version 4.1, Adept Scientific
plc, Letchworth, 2001.
89 D. L. Thorn and R. L. Harlow, Inorg. Chem., 1990, 29,
2017–2019.
90 M. Aizenberg, J. Ott, C. J. Elsevier and D. Milstein, J. Orga-
nomet. Chem., 1998, 551, 81–92.
91 A. L. Raza, J. A. Panetier, M. Teltewskoi, S. A. Macgregor
and T. Braun, Organometallics, 2013, 32, 3795–3807.
92 M. A. Esteruelas, F. J. Lahoz, E. Onate, L. A. Oro and
L. Rodriguez, Organometallics, 1996, 15, 3670–3678.
93 F. Glockling and G. C. Hill, J. Organomet. Chem., 1970, 22,
C48–C50.
94 F. Glockling and G. C. Hill, J. Chem. Soc. A, 1971, 2137–
2141.
95 K. Osakada, T. Koizumi, S. Sarai and T. Yamamoto,
Organometallics, 1998, 17, 1868–1872.
69 D. A. Watson, M. Su, G. Teverovskiy, Y. Zhang, J. Garcia-
Fortanet, T. Kinzel and S. L. Buchwald, Science, 2009, 325,
1661–1664.
70 V. Gouverneur, Science, 2009, 325, 1630–1631.
71 T. Furuya, J. E. M. N. Klein and T. Ritter, Synthesis, 2010,
1804–1821.
96 K. Osakada, K. Hataya and T. Yamamoto, J. Chem. Soc.,
Chem. Commun., 1995, 2315–2316.
97 K. Osakada, S. Sarai, T. Koizumi and T. Yamamoto,
Organometallics, 1997, 16, 3973–3980.
98 R. D. Adams and E. Trufan, Inorg. Chem., 2010, 49, 3029–
3034.
72 T. W. Lyons and M. S. Sanford, Chem. Rev., 2010, 110,
1147–1169.
73 T. Furuya, A. S. Kamlet and T. Ritter, Nature, 2011, 473,
470–477.
74 V. Rauniyar, A. D. Lackner, G. L. Hamilton and
F. D. Toste, Science, 2011, 334, 1681–1684.
75 C. Hollingworth and V. Gouverneur, Chem. Commun.,
2012, 48, 2929–2942.
76 T. Liang, C. N. Neumann and T. Ritter, Angew. Chem., Int.
Ed., 2013, 52, 8214–8264, (Angew. Chem., 2013, 125, 8372–
8423).
99 M. Ahijado, T. Braun, D. Noveski, N. Kocher, B. Neumann,
D. Stalke and H. G. Stammler, Angew. Chem., Int. Ed., 2005,
44, 6947–6951, (Angew. Chem., 2005, 117, 7107–7111).
100 G. Meier and T. Braun, Angew. Chem., Int. Ed., 2011, 50,
3280–3284, (Angew. Chem., 2011, 123, 3338–3342).
101 G. Meier and T. Braun, Angew. Chem., Int. Ed., 2012, 51,
12564–12569, (Angew. Chem., 2012, 124, 12732–12737).
102 After a multiplication of the FID with a gaussian function
the signals at δ = 9.4 and 5.7 ppm resolve to a doublet of
2
2
doublet of doublets [1J(Rh,P) = 86.7; J(P,P) = 21; J(P,P) =
1
2
2
24 Hz and J(Rh,P) = 91; J(P,P) = 21; J(P,P) = 23 Hz] in
the 31P{1H} NMR spectrum.
77 M. G. Campbell and T. Ritter, Chem. Rev., 2015, 115, 612–
633.
78 X. Yang, T. Wu, R. J. Phipps and F. D. Toste, Chem. Rev.,
2015, 115, 826–870.
103 A. W. Addison, T. N. Rao, J. Reedijk, J. Vanrijn and
G. C. Verschoor, J. Chem. Soc., Dalton Trans., 1984, 1349–
1356.
79 Y.-R. Luo, Comprehensive handbook of chemical bond ener- 104 S. E. Boyd, L. D. Field, T. W. Hambley and M. G. Partridge,
gies, CRC Press, 2010. Organometallics, 1993, 12, 1720–1724.
80 P. P. Samuel, A. P. Singh, S. P. Sarish, J. Matussek, 105 A. L. Raza and T. Braun, Chem. Sci., 2015, 6, 4255–4260.
I. Objartel, H. W. Roesky and D. Stalke, Inorg. Chem., 106 M. I. Sladek, T. Braun, B. Neumann and H. G. Stammler,
2013, 52, 1544–1549.
New J. Chem., 2003, 27, 313–318.
81 M. Aizenberg and D. Milstein, Science, 1994, 265, 359–361. 107 N. A. Jasim, R. N. Perutz, A. C. Whitwood, T. Braun,
82 M. Aizenberg and D. Milstein, J. Am. Chem. Soc., 1995,
117, 8674–8675.
J. Izundu, B. Neumann, S. Rothfeld and H. G. Stammler,
Organometallics, 2004, 23, 6140–6149.
Dalton Trans.
This journal is © The Royal Society of Chemistry 2016

View Article Online
Dalton Transactions
Paper
108 S. Burling, P. I. P. Elliott, N. A. Jasim, R. J. Lindup, 132 M. Paneque, S. Sirol, M. Trujillo, E. Carmona,
J. McKenna, R. N. Perutz, S. J. Archibald and
A. C. Whitwood, Dalton Trans., 2005, 3686–3695.
109 I. M. Piglosiewicz, S. Kraft, R. Beckhaus, D. Haase and
W. Saak, Eur. J. Inorg. Chem., 2005, 938–945.
E. Gutierrez-Puebla, M. A. Monge, C. Ruiz, F. Malbosc,
C. Serra-Le Berre, P. Kalck and M. Etienne, Chem. – Eur. J.,
2001, 7, 3868–3879.
133 J. Vicente, J. Gil-Rubio, J. Guerrero-Leal and D. Bautista,
Organometallics, 2004, 23, 4871–4881.
110 U. Jager-Fiedler, P. Arndt, W. Baumann, A. Spannenberg,
V. V. Burlakov and U. Rosenthal, Eur. J. Inorg. Chem., 134 M. J. Bennett and P. B. Donaldson, J. Am. Chem. Soc.,
2005, 2842–2849. 1971, 93, 3307–3308.
111 T. Schaub, P. Fischer, A. Steffen, T. Braun, U. Radius and 135 M. J. Bennett and P. B. Donaldson, Inorg. Chem., 1977, 16,
A. Mix, J. Am. Chem. Soc., 2008, 130, 9304–9317. 1585–1589.
112 S. Erhardt and S. A. Macgregor, J. Am. Chem. Soc., 2008, 136 C. Tejel, M. A. Ciriano, S. Jimenez, V. Passarelli and
130, 15490–15498.
113 A. Nova, S. Erhardt, N. A. Jasim, R. N. Perutz,
J. A. Lopez, Angew. Chem., Int. Ed., 2008, 47, 2093–2096,
(Angew. Chem., 2008, 120, 2123–2126).
S. A. Macgregor, J. E. McGrady and A. C. Whitwood, J. Am. 137 T. Miyaji, M. Kujime, S. Hikichi, Y. Moro-oka and
Chem. Soc., 2008, 130, 15499–15511.
M. Akita, Inorg. Chem., 2002, 41, 5286–5295.
138 T. Yoshida, D. L. Thorn, T. Okano, S. Otsuka and
J. A. Ibers, J. Am. Chem. Soc., 1980, 102, 6451–6457.
139 P. J. Zhao and J. F. Hartwig, Organometallics, 2008, 27,
4749–4757.
140 P. D. Prince, G. S. McGrady and J. W. Steed, New J. Chem.,
2002, 26, 457–461.
141 G. M. Sheldrick and T. R. Schneider, SHELXL: High-resolu-
tion refinement, 1997.
142 G. M. Sheldrick, SHELXS-2013, Program for Crystal Struc-
ture Solution, University of Göttingen, 2013.
143 G. M. Sheldrick, SHELXL-2013, Program for Crystal Struc-
ture Refinement, University of Göttingen, 2013.
144 G. M. Sheldrick, SADABS, Program for Empirical Absorption
Correction, University of Göttingen, 1996.
114 V. V. Grushin, Acc. Chem. Res., 2010, 43, 160–171.
115 A. Nova, M. Reinhold, R. N. Perutz, S. A. Macgregor and
J. E. McGrady, Organometallics, 2010, 29, 1824–1831.
116 E. Jiao, F. Xia and H. Zhu, Comput. Theor. Chem., 2011,
965, 92–100.
117 S. I. Kalläne, M. Teltewskoi, T. Braun and B. Braun,
Organometallics, 2015, 34, 1156–1169.
118 O. Blum, F. Frolow and D. Milstein, J. Chem. Soc., Chem.
Commun., 1991, 258–259.
119 M. K. Whittlesey, R. N. Perutz and M. H. Moore, Chem.
Commun., 1996, 787–788.
120 B. L. Edelbach and W. D. Jones, J. Am. Chem. Soc., 1997,
119, 7734–7742.
121 U. von Allwörden and G. V. Röschenthaler, Chem.-Ztg.,
1988, 112, 69–76.
145 A. L. Spek, J. Appl. Crystallogr., 2003, 36, 7–13.
122 A. Penner and T. Braun, Eur. J. Inorg. Chem., 2011, 2579– 146 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
2587.
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone,
B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng,
J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, T. Vreven, J. A. Montgomery Jr., J. E. Peralta,
F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin,
V. N. Staroverov, R. Kobayashi, J. Normand,
K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar,
J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene,
J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo,
R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin,
R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin,
K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador,
J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö. Farkas,
J. B. Foresman, J. V. Ortiz, J. Cioslowski and D. J. Fox, Gaus-
sian 09, Revision D.01, Gaussian, Inc., Wallingford, CT, 2013.
147 K. A. Peterson, J. Chem. Phys., 2003, 119, 11099–11112.
123 H. Baumgarth, T. Braun, B. Braun, R. Laubenstein and
R. Herrmann, Eur. J. Inorg. Chem., 2015, 3157–3168.
124 J.-C. Choi, K. Kohno, M. Otsuka, H. Yasuda and
T. Sakakura, Organometallics, 2011, 30, 6060–6062.
125 T. Kashiwabara, K. Fuse, T. Muramatsu and M. Tanaka,
J. Org. Chem., 2009, 74, 9433–9439.
126 F. A. Cotton, S. J. Kang and S. K. Mandal, Inorg. Chim.
Acta, 1993, 206, 29–39.
127 F. A. Cotton, K. R. Dunbar, C. T. Eagle, L. R. Falvello and
A. C. Price, Inorg. Chem., 1989, 28, 1754–1757.
128 Y. Takahashi, M. Hashimoto, S. Hikichi, M. Akita and
Y. Moro-oka, Angew. Chem., Int. Ed., 1999, 38, 3074–3077,
(Angew. Chem., 1999, 111, 3259–3262).
129 M. J. Bennett and P. B. Donaldson, Inorg. Chem., 1977, 16,
1581–1585.
130 K. Osakada, K. Hataya and T. Yamamoto, Inorg. Chem.,
1993, 32, 2360–2365.
131 X.-Y. Yu, B. O. Patrick and B. R. James, Organometallics, 148 K. A. Peterson, D. Figgen, M. Dolg and H. Stoll, J. Chem.
2006, 25, 4870–4877.
Phys., 2007, 126, 124101.
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