Dehydrogenation of cycloalkanes at rhodium complexes bearing fluorinated cyclopentadienyl ligands

Article abstract of DOI:10.1016/j.jfluchem.2015.09.014

The fluorinated cyclopentadienyl complexes [Rh(η⁵-C₅H₄CH₂CH₂C₆F₁₃)(CO)₂] (2), [Rh(η⁵-C₅H₄CH₂CH₂C₈F₁₇)(CO)₂] (3), [Rh(η⁵-C₅H₄CH₂CH₂C₁₀F₂₁)(CO)₂] (4), [Rh(η⁵-C₅H₄CH₂CH₂C_nF_2n+1)(CO)(PEt₃)] (7: n = 6; 8: n = 8; 9: n = 10) and [Rh(η⁵-C₅H₄CH₂CH₂C_nF_2n+1)(CO){P(CH₂CH₂C₆F₁₃)₃}] (10: n = 8; 11: n = 10) were synthesized and their reactivity was investigated. Compound 3 converts at room temperature into the trinuclear complex [Rh₂(η⁵-C₅H₄CH₂CH₂C₈F₁₇)₂(μ-CO)₂Rh(η⁵-C₅H₄CH₂CH₂C₈F₁₇)(CO)] (6). The complexes 9 and 11 were employed in dehydrogenation reactions of cycloalkanes in C₆F₁₄/hydrocarbon mixtures. Photocatalytic conversions were observed and a turnover number of 16 for the dehydrogenation of cyclooctane with complex 11 was obtained.

Full text of DOI:10.1016/j.jfluchem.2015.09.014

Journal of Fluorine Chemistry 180 (2015) 192–200
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Dehydrogenation of cycloalkanes at rhodium complexes bearing
fluorinated cyclopentadienyl ligands
*
Frank Liebau, Thomas Braun , Beatrice Braun
Humboldt-Universita¨t zu Berlin, Department of Chemistry, Brook-Taylor-Str. 2, 12489 Berlin, Germany
A R T I C L E I N F O
A B S T R A C T
The fluorinated cyclopentadienyl complexes [Rh(h5-C5H4CH2CH2C6F13)(CO)2] (2), [Rh(h5
-
Article history:
C5H4CH2CH2C8F17)(CO)2] (3), [Rh(h5-C5H4CH2CH2C10F21)(CO)2] (4), [Rh(h5-C5H4CH2CH2CnF2n+1)(CO)(-
PEt3)] (7: n = 6; 8: n = 8; 9: n = 10) and [Rh(h5-C5H4CH2CH2CnF2n+1)(CO){P(CH2CH2C6F13)3}] (10: n = 8; 11:
n = 10) were synthesized and their reactivity was investigated. Compound 3 converts at room temperature
Received 14 July 2015
Received in revised form 23 September 2015
Accepted 26 September 2015
Available online 3 October 2015
into the trinuclear complex [Rh2(h5-C5H4CH2CH2C8F17)2( -CO)2Rh(h5-C5H4CH2CH2C8F17)(CO)] (6). The
m
complexes 9 and 11 were employed in dehydrogenation reactions of cycloalkanes in C6F14/hydrocarbon
mixtures. Photocatalytic conversions were observed and a turnover number of 16 for the dehydrogenation
of cyclooctane with complex 11 was obtained.
Keywords:
Dehydrogenation reactions
Rhodium
ß 2015 Elsevier B.V. All rights reserved.
Perfluorinated solvents
C–H activation
Cyclopentadienyl complexes
1. Introduction
2. Results and discussion
The homogenous catalytic dehydrogenation of hydrocarbons in
the absence of any H2 accepting sacrificial olefin is an ongoing topic
in metal catalyzed C–H activation reactions [1]. For instance, pincer
complexes show a high catalytic activity toward cyclooctane [2].
Recently, Beller et al. used [RhCl(CO)(PR3)2] (R = Me, Et, Ph) as a
precatalyst in photochemical dehydrogenation reactions [3]. It was
suggested that the highly reactive tricoordinated rhodium(I)
complex [RhCl(PR3)2] is generated as an intermediate by a
photolytic cleavage of the Rh–CO bond [4]. The complexes
[RhCp{P(CH2CH2CN)3}(CO)] and [RhCp(PTA)(CO)] (PTA = 1,3,5-
triaza-7-phosphaadamantane) were applied in photoassisted
dehydrogenation reactions of octane and cyclooctane without
The complex [Rh(h5-C5H4Rf17)(CO)2] (3) (Rf17 = CH2CH2C8F17
was prepared by a reaction of in situ generated K[C5H4Rf17] and
[Rh( -Cl)(CO)2]2 (Scheme 1) [8]. A comparable synthesis of
)
m
complex [Rh(h5-C5H4Rf13)(CO)2] (2) was described earlier [9],
and compound [Rh(h5-C5H4Rf21)(CO)2] (4) (Rf21 = CH2CH2C10F21
)
was also prepared before by Hughes et al. [10].
The CO ligands in 3 give rise to a doublet in the 13C{1H} NMR
spectrumatd = 192.3 ppm(JC,Rh = 83.4 Hz).TheIRspectrum(ATR)of
neat 3 exhibits strong absorption bands for the CF2 and CF3 groups of
the fluorinated chain between
n
˜ ¼ 1139 and 1239 cmꢀ1. The two
absorption bands at
n
˜ ¼ 1976 and 2044 cmꢀ1 can be assigned to the
vibrations of the CO ligands. Complex [Rh(Cp)(CO)2] exhibits
comparable C–O stretching vibrations [11]. This suggests that the
electronicinfluenceofthe fluorinated chain onthe rhodium centeris
negligible [12]. The observation is also in accordance with other
literature data reported by Hughes et al. [8,10]. However, Gladysz
et al. found that at [M(h5-C5H5-mRfm)(CO)n] (M = Mn, Re, Rh;
Rf = CH2CH2C8F17; m = 1, 3–5; n = 2, 3) an increasing number of
fluorinated chains leads to a lower electron density at the metal
center [12c].
additional hydrogen acceptor [5]. We demonstrated that [Ir(h5
-
C5H4Rf13)(CO)2] (1) (Rf13 = CH2CH2C6F13) is active in the photo-
catalytic dehydrogenation of cyclic hydrocarbons [6]. The studies
involve reactions in cyclohexane as well as in perfluoromethylcy-
clohexane [6]. However, the turnover numbers were rather low. In
this paper we report on the synthesis and reactivity of rhodium
complexes bearing fluorinated ‘‘ponytails’’. The photolytic activa-
tion of alkanes in perfluorinated/hydrocarbon solvent mixtures [7]
was investigated.
A stepwise elimination of CO ligands at [Rh(h5-C5H4Rf17)(CO)2]
(3) was observed in benzene at room temperature which led to the
formation of the binuclear complex [Rh2(h5-C5H4Rf17)2(CO)2(
m–
*
Corresponding author.
CO)] (5) (Scheme 2). A similar reactivity pattern was observed
E-mail address: thomas.braun@chemie.hu-berlin.de (T. Braun).
http://dx.doi.org/10.1016/j.jfluchem.2015.09.014
0022-1139/ß 2015 Elsevier B.V. All rights reserved.

F. Liebau et al. / Journal of Fluorine Chemistry 180 (2015) 192–200
193
Scheme 1. Synthesis of [Rh(h5-C5H4Rf17)(CO)2] (3).
Scheme 2. Formation of the polynuclear complexes 5 and 6 from 3.
before at non-fluorinated complexes to give for instance
[Rh2Cp2(CO)2( -CO)] due to dissociation of CO [12i,13].
A comparison of the 1H NMR spectra of 3 and 5 in C6D6 reveals
shifts to lower field of the virtual triplets which are assigned to the
hydrogen atoms at the cyclopentadienyl ring (Fig. 1(a)). The signals
appear at
d
= 4.75 and 4.68 ppm for 3 and at
d
= 5.02 and 4.82 ppm
m
for 5. The absorption band for the bridging
observed at
an absorption band at
m-C–O ligand in 5 was
n
˜ ¼ 1847 cmꢀ1. The terminal bound CO ligands give
n
˜ ¼ 1976 cmꢀ1 [12h].
After four weeks at room temperature of the mixture of 3 and 5,
a further loss of CO ligands was observed and the trinuclear
m
complex [Rh2(h5-C5H4Rf17)2( -CO)2Rh(h5-C5H4Rf17)(CO)] (6) was
generated, which bears also terminal and bridging CO ligands. The
1H NMR spectrum of 6 in C6D6 shows resonances at
= 5.09 and
d
5.01 ppm (Fig. 1(b)). Absorption bands in the IR spectrum appear at
n
¼ 1949 and 1743 cmꢀ1. Crystallization of the trinuclear com-
˜
pound 6 by evaporation of a C6D6 solution gave small needles
which were suitable for an X-ray crystallographic analysis. The
molecular structure is depicted in Fig. 2.
In complex 6 two bridged carbonyl ligands are bounded at Rh1
and Rh2. The rhodium atoms form a distorted triangle, whereas the
angle at Rh3 with 58.05(3)8 is slightly smaller than the inside
angles at Rh1 (60.87(3)8) and Rh2 with (61.08(3)8). Rh3 is in
addition coordinated by a terminal bound CO ligand. As expected,
all perfluorinated chains are helically twisted [14]. The two
fluorinated ponytails of the Cp ligands at Rh1 and Rh2 are aligned
˚
next to each other with Fꢁ ꢁ ꢁF separations of 2.76(1) A (F21ꢁ ꢁ ꢁF36)
Fig. 1. Part of the 1H NMR spectra in C6D6 of 3 and 5 (a) as well as of 6 (b).
and 2.75(2) A (F24ꢁ ꢁ ꢁF40). The freestanding fluorinated chains of
˚

194
F. Liebau et al. / Journal of Fluorine Chemistry 180 (2015) 192–200
˚
Fig. 2. Molecular structure of 6. Hydrogen atoms are omitted for clarity. Selected bond length in A: Rh1-Ct2 1.883(5) (Ct = Cp ring centroid), Rh1-C17 1.998(9), Rh1-C18
1.951(8), Rh2-Ct3 1.896(5), Rh2-C17 1.960(8), Rh2-C18 2.015(10), Rh3-Ct1 1.897(5), Rh3-C1 1.832(10), Rh1-Rh2 2.6335(10), Rh1-Rh3 2.7164(10), Rh2-Rh3 2.7109(10), O1-
C1 1.156(12), O2-C17 1.174(11), O3-C18 1.178(11).
By irradiation of 2–4 with a 150 W Xe arc lamp, no reactivity
toward cyclooctane, cyclohexane, cyclopentane or methylcyclo-
hexane was observed, but decomposition to give unknown
presumably bi- and trinuclear compounds. This is in contrast to
the reactivity of [Ir(h5-C5H4Rf13)(CO)2] (1) toward cyclohexane
which led to dehydrogenation by irradiation [6]. However,
irradiation of the complexes [Rh(h5-C5H4Rf13/17/21)(CO)2] (2–4)
in the presence of triethylphosphine in pentane solutions yielded
[Rh(h5-C5H4Rf13/17/21)(CO)(PEt3)] (7–9) by dissociation of one CO
ligand (Scheme 3).
For the CO ligand in 7, a doublet of doublet was observed at
2
d
= 196.6 ppm (JC,Rh = 87 Hz; JC,P = 25 Hz) in the 13C{1H} NMR
spectrum. The 31P{1H} NMR spectrum shows
= 44.8 ppm with a coupling constant of JP,Rh = 186 Hz. The
isotopologue [Rh(h5-C5H4Rf17)(13CO)(PEt3)] (70) was prepared
from [Rh(h5-C5H4Rf13)(13CO)2] (30). In the 31P{1H} NMR spectrum
of 70 the phosphine signal splits into a doublet of doublet due to the
coupling with 13C nucleus of 2JP,C = 25 Hz. The UV–vis spectrum of
a doublet at
d
Fig. 3. Part of the 1H NMR spectrum of 6 in THF-d8.
7 in C6H6 exhibits three absorption bands at lmax = 219, 234 and
neighboring molecules in the crystal exhibit comparable short
Fꢁ ꢁ ꢁF distances. Two contacts with a radius shorter than the van
der Waals radii of F are present between symmetry equivalent
molecules in the crystal structure of complex 6. The shortest
295 nm and weak features at 349 and 425 nm (Fig. 4). The
strongest absorption might be assigned to a ligand-field transition
by comparison to the assignments for [RhCp(CO)2] [12g]. An UV–
vis spectrum of 7 in perfluoromethylcyclohexane gives approxi-
mately the same bands. In contrast to the phosphine free species
2–4, complexes 7–9 are stable in solution. The analytical data of
the compounds 8 and 9 are comparable to those of 7.
˚
contact is achieved for F24ꢁ ꢁ ꢁF48* and it amounts to 2.656(18) A
(* represents the asymmetric residue defined by symmetry
operation 1 + x, y, z). Note that the structure of the rhodium(I)
complex [Rh(h5-C5Me4Rf13)(CO)2] bearing a fluorinated tetra-
When a mixture of 4 and PEt3 was irradiated in benzene, a
ˇ
´
methylcyclopentadienyl ligand was reported by Cermak et al.
[15].
signal for a hydrido ligand at
d
= ꢀ13.76 ppm (JH,Rh = 38.9 Hz,
2JH,P = 30.8 Hz) was observed after 3 h in the 1H NMR spectrum, in
addition to the formation of 9. Additional multiplet signals in the
aromatic region were also detected. We speculate that a C–H
activation occurred and [Rh(h5-C5H4Rf21)(H)(Ph)(PEt3)] was
generated simultaneously to 9 (ratio 1:10 according to the 1H
NMR spectrum). Comparable photochemical conversions by
formation of an intermediate 16 electron species starting from
[Rh(Cp*)(H)2(PMe3)] were reported by Jones et al. to give
[Rh(Cp*)(H)(Ph)(PMe3)] in benzene [16].
Unlike the spectrum in C6D6 solution, the 1H NMR spectrum of 6
in THF-d8 shows two sets of resonances at
d = 5.59 and 5.40 ppm
and at = 5.66 and 5.48 ppm which integrate in a ratio of 2:1
d
(Fig. 3). This indicates that only two cyclopentadienyl ligands are
equivalent on the NMR timescale. However, in C6D6 or toluene-d8
only one set of signals was observed in the 1H NMR spectrum even
at low temperature, which indicates a dynamic behavior rendering
all signals for the Cp ligands to be equivalent.
Scheme 3. Synthesis of the rhodium phosphine complexes 7–9.

F. Liebau et al. / Journal of Fluorine Chemistry 180 (2015) 192–200
195
1930 cmꢀ1 (8 and 9) for the CO vibration. For [RhCp(CO)(PEt3)]
(12) a band at
n
˜ ¼ 1928 cmꢀ1 was reported [18]. This indicates
again a negligible influence of the fluorinated chain on electron
density at the metal center [6,8]. In contrast, for the complexes
[Rh(h5-C5H4Rf17/21)(CO)(PRf133)] (10, 11) the electron withdraw-
ing character of the three additional fluorinated chains bound at
the phosphorus atom have a considerable impact. Their IR spectra
give bands of medium intensity at
n
˜ ¼ 1965 (10) and 1964 cmꢀ1
(11).
Complexes 7–9 are soluble both in hydrocarbons and the
perfluorinated solvent C7F14. In contrast, complexes 10 and 11 are
only soluble in C7F14. The non-fluorinated compound [RhCp(CO)(-
PEt3)] (12) shows no solubility in C7F14. Photolysis of hydrocarbon
solutions of the fluorinated complexes 7–9 with a 150 W Xe arc
lamp did not lead to any C–F activation product of the fluorinated
chain [19]. However, by irradiation of solutions of 7–9 in
cyclopentane, cyclohexane, cyclooctane or methylcyclohexane a
dehydrogenation of the cycloalkanes was observed and a signifi-
cant amount of products were identified (Scheme 5, Fig. 5).
Complex 9 was used for dehydrogenation reactions of cyclooctane
in the neat substrate as well as under biphasic conditions. The
reactivity of the fluorinated complexes 10 and 11 was tested by
Fig. 4. UV–vis spectrum of [Rh(h5-C5H4Rf13)(CO)(PEt3)] (7) in C6H6.
Heating a solution of [Rh(h5-C5H4Rf17)(CO)2] (3) and equi-
molar amounts of tris(1H,1H,2H,2H-perfluorooctyl)phosphine
[17] in perfluoromethylcyclohexane to 80 8C gave [Rh(h5
-
irradiating them in C7F14/alkane (
[20]. Photolysis of 10 and 11 in
c
vol = 3/2) mixtures (Scheme 6)
mixture of C7F14 and
C5H4Rf17)(CO)(PRf133)] (10) (Scheme 4). Note that photolytic
experiments at 3 did not lead to 10. However, the Rh(I) complex
[Rh(CO)(h5-C5H4Rf21)(PRf133)] (11) was described before by
Herrera et al. and 10 was synthesized in a comparable way
[10]. The 31P{1H} NMR spectrum of 10 in C7F14 exhibits a doublet
a
cyclopentane, cyclohexane and methylcyclohexane led to dehy-
drogenations. Note that C7F14 and cyclopentane form a homoge-
neous mixture at room temperature, whereas cyclohexane and
methylcyclohexane form a biphasic system with C7F14. In addition,
dehydrogenation experiments in neat cyclooctane with the non-
fluorinated complex 12 were run. After 14 days irradiation,
cyclooctene was produced in very low quantity. Precipitation of a
brown insoluble product of decomposition during photolytic
reaction was observed.
at
d
= 45.23 ppm (JP,Rh = 200.8 Hz). The 13C{1H} NMR spectrum
= 193.75 ppm for the CO ligand with
shows a resonance at
d
2
coupling constants of JC,Rh = 84.4 and JC,P = 25.7 Hz.
The IR spectra of the compounds [Rh(h5-C5H4Rf13/17/
21)(CO)(PEt3)] (7–9) give strong bands at
n
˜ ¼ 1931 (7) and
Scheme 4. Synthesis of the rhodium complexes 10 and 11 [10].
Scheme 5. Photochemical dehydrogenation of cycloalkanes mediated by the complexes 7–12.

196
F. Liebau et al. / Journal of Fluorine Chemistry 180 (2015) 192–200
methylcyclohexane yielded methylcyclohexene and toluene
(ratio 1:1.4, entry 3). On using [Rh(h5-C5H4Rf21)(CO)(PRf13)]
(11) in C7F14/alkane ( vol = 3/2) mixtures a higher reactivity was
c
observed (entries 6–10). The highest TON of 16 was obtained for
the dehydrogenation of cyclooctane (entry 10).
Mechanistically, we propose a photolytic induced CO ligand
abstraction and the generation of 16-electron species [Rh(h5
-
C5H4R)(PR’3)] (R = H, Rf13/17/21; R0 = Et, Rf13) [21]. Note also that it
is conceivable that a fluorinated chain can act as a hemilabile
coordinating entity to stabilize reactive intermediates by addi-
tional metal–fluorine interactions [2,22]. An oxidative addition
of a C–H bound at the rhodium center in [Rh(h5-C5H4R)(PR3 )]
0
gives then the intermediates [Rh(h5-C5H4R)(alkyl)(H)(PR3 )] A
0
(Scheme 6), which could not be observed by NMR spectroscopy.
Subsequent
b-hydrogen elimination reaction at the metal
center gives the olefin and the dihydrido species [Rh(h5
-
Fig. 5. 1H NMR spectra of olefinic region after photolysis of [Rh(h5
C5H4Rf17)(CO)(PEt3)] (8) in cyclooctane over ꢂ6 days.
-
C5H4R)(H)2(PR03)] B. This reaction step presumably requires a
vacant coordination site at the metal center, which can for
instance be generated by a change of the hapticity of the C5H4
ligand by ring slippage [12d,23]. Reductive elimination of
dihydrogen and subsequent oxidative addition of another alkane
completes the catalytic cycle. An analogous mechanism was
Quantitative data for the dehydrogenation reactions were
determined for the complexes 9 and 11 (Table 1), which are the
complexes with the longest fluorinated chains at the C5H4 ligand.
To compare yields of the conversions the amount of generated
double bonds was taken into account. The cycloalkenes were
characterized and quantified by 1H NMR spectroscopy. In addition
GC–MS data were used for the identification of the alkenes. The
formation of H2 was also observed by 1H NMR spectroscopy. A
photochemical dehydrogenation in neat cyclooctane by complex
suggested for comparable transformations at [Ir(h5
-
C5H4Rf13)(CO)2] (1) [6]. Note also that the formation of H2 might
be favored in a perfluorinated solvent because of the presence of
cavities [24].
To evaluate a possible photolytic dissociation of a CO ligand in
[Rh(h5-C5H4Rf21)(CO)(PRf133)] (11), we studied the photolytic
9
resulted in a TON = 4 (entry 4). A dehydrogenation of
Scheme 6. Proposed mechanism for the photolytic dehydrogenation of alkane.
Table 1
Data for the dehydrogenation experiments. Calculations are done by integration of the signals for the olefinic hydrogen atoms of alkenes formed versus a mesitylene standard
in the 1H NMR spectra. TON (turn over numbers) are based on the amount of C–C bonds converted into C5C bonds.
Entry
Complex
mmol Complex
Substrate cycloalkane
Product(s)
TON (nC55C/mcat.
)
Time (h)
1a
2a
3a
4a
5b
6c
7b
8b
9b
10b
9
0.20
0.28
0.43
0.38
1.09
0.20
0.10
0.19
0.09
0.02
C5H10
C5H8
1
1
168
168
168
168
90
9
C6H12
C6H10
9
C6H11CH3
C8H16
C6H9CH3, C6H5CH3 (1:1.4)
2
9
C8H14
4
9
C8H16
C8H14
1
11
11
11
11
11
C5H10
C5H8
3
48
C6H12
C6H10
5
90
C6H11CH3
C8H16
C6H9CH3, C6H5CH3 (2.3:1)
6
90
C8H14
C8H14
6
90
C8H16
16
90
a
Solution of the metal complex precursor in 0.2 ml alkane.
b
c
In C7F14/alkane (
cvol = 3/2) biphasic system.
Homogeneous phase.

F. Liebau et al. / Journal of Fluorine Chemistry 180 (2015) 192–200
197
The UV–vis spectra were acquired with
a
Cary 100 scan
spectrophotometer (Varian). GC analyses were performed with a
Varian GC equipped with an Agilent VF-WAXms column coupled to
an EI (electron ionization). For all photochemical experiments an
L.O.T. Oriel 150 W Xe arc lamp was used. Liquid injection field
desorption ionization mass spectra were measured at a Micromass
Q-TOF 2 mass spectrometer equipped with a LIFDI 700 (Linden
CMS) ion source. [Rh(m-Cl)(CO)2] [25], Triethylphosphine [26],
tris(1H,1H,2H,2H-perfluorooctyl)phosphine [17b,27], [RhCp(CO)2]
[12e], [RhCp(CO)(PEt3)] (12) [12g], C5H5CH2CH2CnF2n+1 (n = 6, 8,
10) [8], [Rh(h5-C5H4Rf21)(CO)2] (4) [10] and [Rh(h5
-
C5H4Rf21)(CO)(PRf3)] (11) [10] were prepared according to the
literature. Abbreviation for virtual coupling constants: N = J.
S
4.2. Synthesis of [Rh(h5-C5H4Rf13)(CO)2] (2) and [Rh(h5
C5H4Rf13)(13CO)2] (20)
-
Fig. 6. Part of the 13C{1H} NMR spectrum after photolysis of 11 in
perfluoromethylcyclohexane in the presence of 13CO.
C5H5Rf13 (670.3 mg, 1.6 mmol) was dissolved in 10 ml THF and
cooled to ꢀ80 8C. The solution was then added to a suspension of
KH (94 mg, 2.3 mmol) in 15 ml THF. The mixture was stirred and
allowed to warm up to 5 8C within 4 h and then cooled to ꢀ80 8C. At
behavior in the presence of 13CO. However, irradiation of a mixture
of [Rh(h5-C5H4Rf21)(CO)(PRf133)] (11) led to a displacement of CO
and the fluorinated phosphine, demonstrated by the appearance of
ꢀ80 8C a solution of [Rh(
m-Cl)(CO)2]2 (331.6 mg, 853 mmol) in
a signal in the 13C{1H} NMR spectrum at
d
= 190.2 ppm with a
10 ml THF was quickly added via a cannula. The mixture was
allowed to warm to room temperature and stirred for 24 h. The
suspension was filtered, the solvent removed from the filtrate in
vacuo and the residue extracted with hexane (2ꢃ 15 ml). The
brown hexane solution was cooled to ꢀ80 8C, stored for two hours
and then filtered. Removal of all volatiles from the filtrate yields a
doublet coupling of JC,Rh = 83 Hz, which we tentatively assign to
[Rh(h5-C5H4Rf21)(13CO)2] (40) (Fig. 6) [10]. Thus, in the presence of
additional CO a dicarbonyl complex is accessible.
3. Conclusions
brown oil of 2. Yield: 837.9 mg (86%). UV–vis (C6D6):
(vs), 295 (s), 345 (sh) nm. IR (ATR, neat):
˜ 2043 and 1975 (s, CO),
1236–1143 (s br, CF) cmꢀ1. 1H NMR (300.1 MHz, C6D6):
4.75 (vt,
2H, N = 2.0 Hz, C5H4), 4.67 (vt, 2H, N = 2.0 Hz, C5H4), 2.12 (m, 2H,
CH2CH2CF2), 1.94 (m br, 2H, CH2CF2). 13C{1H} NMR (75.5 MHz,
l 220 (s), 234
In conclusion,
a
variety of rhodium complexes bearing
n
fluorinated alkyl chains at a cyclopentadienyl ligand were
investigated. Derivatives with a fluorinated phosphine ligand
d
show
are not soluble in hydrocarbons. Complex [Rh2(h5
C5H4Rf17)2( CO)2Rh(h5-C5H4Rf17)(CO)] (6) was characterized
by X-Ray crystallography. The fluorinated complexes [Rh(h5
a
high solubility in perfluoromethylcyclohexane and
-
C6D6): d 192.2 (d, JC,Rh = 84 Hz, CO), 109.6 (d, JC,Rh = 4 Hz, Cipso), 87.9
2
m
(d, JC,Rh = 3 Hz, CH), 86.6 (d, JC,Rh = 4 Hz, CH), 34.1 (t, JC,F = 22 Hz,
-
CH2CF2), 18.89 (m, CH2CH2CF2), the signals for the CF2 and CF3
C5H4Rf21)(CO)(PEt3)] (9) and [Rh(h5-C5H4Rf21)(CO)(PRf133)] (11)
exhibit a higher activity toward the dehydrogenation of alkanes
than complex [RhCp(CO)(PEt3)] (12), for which no catalytic
reaction was found. In the presence of a fluorinated solvent 11
shows the highest activity of all tested complexes. It has been
speculated before that fluorinated entities which are tethered at
groups were not detected. 19F{1H} NMR (282.4 MHz, C6D6):
d
ꢀ81.3
4
3
(tt, 3F, JF,F = 10 Hz, JF,F = 2 Hz, CF3), ꢀ114.3 (m, 2F, CF2), ꢀ122.1
(m, 2F, CF2), ꢀ123.1 (m, 2F, CF2), ꢀ123.7 (m, 2F, CF2), ꢀ126.4 (m, 2F,
CF2).
The synthesis of [Rh(h5-C5H4Rf13)(13CO)2] (20) was done
analogously starting from C5H5Rf13 (412.1 mg, 1.0 mmol), KH
the complex or originate from the solvent might have
a
-
(64.2 mg, 1.6 mmol) and [Rh(
in 15 ml THF to yield a brown oil of 20. Yield: 397.3 mg (80%). IR
m mmol)
-Cl)(13CO)2]2 (170.4 mg, 434
stabilizing influence on intermediates such as {Rh(h5
C5H4Rf21)(CO)} [6,7f].
(ATR, neat): n .
˜ 1994 and 1928 (s, 13CO), 1234–1143 (s br, CF) cmꢀ1
1H, 13C{1H} and 19F{1H} NMR: see 2.
4. Experimental
4.3. Synthesis of [Rh(h5-C5H4Rf17)(CO)2] (3)
4.1. General
C5H5Rf17 (153.7 mg, 300
and cooled to ꢀ80 8C. The solution was then added to a
suspension of KH (23.9 mg, 400 mol) in 20 ml THF. The
mixture was stirred and allowed to warm up to 5 8C within
4 h and then cooled to ꢀ80 8C. A solution of [Rh( -Cl)(CO)2]2
(58.3 mg, 150 mol) in 15 ml THF was quickly added via a
cannula. The mixture was allowed to warm to room temperature
and stirred for 24 h. The suspension was filtered, the solvent
removed from the filtrate in vacuo and the residue extracted
with hexane (2ꢃ 15 ml). The brown hexane solution was cooled
to ꢀ80 8C, stored for two hours and then filtered. Removal of all
volatiles from the filtrate yielded a brown oil of 3. Yield:
mmol) was dissolved in 30 ml THF
All reactions were carried out under an argon atmosphere using
standard Schlenk techniques. Dry and oxygen free solvents were
prepared using standard procedures. Perfluoromethylcyclohexane
was dried over CaH2, distilled and degassed with six freeze pump
thaw cycles. Cyclohexane, cyclopentane, methylcyclohexane and
cyclooctane were dried over sodium, distilled and stored over a
molecular sieve. NMR spectra in C7F14 were acquired using a C6D6
capillary as an external standard. NMR analyses were carried out
with a Bruker DPX or AVIII 300 spectrometer. The chemical shifts
are reported in parts per million (ppm). The 1H NMR chemical
m
m
m
shifts were referenced to residual C6D5H at
d7 at
7.09 ppm. The 13C NMR chemical shifts were referenced to
C6D6 at
128.08 ppm. The 31P NMR and 19F NMR spectra were
referenced externally to 85% H3PO4 at 0 ppm and to C6F6 at
d 7.16 ppm or toluene-
d
138.7 mg (69%). IR (ATR, neat):
n
˜ 2043 and 1977 (s, CO), 1240–
d
1145 (m, br, CF) cmꢀ1. 1H NMR (300.1 MHz, C6D6):
d
4.75 (vt, 2H,
d
d
N = 2.0 Hz, C5H4), 4.68 (vt, 2H, N = 2.0 Hz, C5H4), 2.13 (m, 2H,
CH2CH2CF2), 1.95 (m, br, 2H, CH2CF2). 13C{1H} NMR (75.5 MHz,
162.9 ppm. IR spectra were recorded with a Bruker vertex 70
spectrometer, which was equipped with an ATR unit (diamond).
C6D6):
d 192.2 (d, JC,Rh = 83 Hz, CO), 109.6 (d, JC,Rh = 4 Hz, Cipso),

198
F. Liebau et al. / Journal of Fluorine Chemistry 180 (2015) 192–200
87.9 (d, JC,Rh = 3 Hz, CH), 86.6 (d, JC,Rh = 4 Hz, CH), 34.1 (t,
2JC,F = 22 Hz, CH2CF2), 18.9 (m, CH2CH2CF2), the signals for the
CF2 and CF3 groups were not detected. 19F{1H} NMR (282.4 MHz,
4.6. Synthesis of [Rh(h5-C5H4Rf17)(CO)(PEt3)] (8)
[Rh(h5-C5H4Rf17)(CO)2] (3) (631.8 mg, 940
solved in 20 ml hexane and PEt3 (0.2 ml, 1.41 mmol) was added
dropwise. The mixture was stirred and irradiated for 16 h. The
resulting suspension was filtered, all volatiles were removed in
vacuo from the filtrate and the residue lyophilized three times to
m
mol) was dis-
C6D6):
d
ꢀ81.3 (tt, 3F, 4JF,F = 9 Hz, 3JF,F = 2 Hz, CF3), ꢀ114.2 (m, 2F,
CF2), ꢀ121.9 (m, 2F, CF2), ꢀ122.1 (m, 4F, CF2), ꢀ123.0 (m, 2F,
CF2), ꢀ123.6 (m, 2F, CF2), ꢀ126.4 (m, 2F, CF2).
4.4. Formation of [Rh2(h5-C5H4Rf17)2(CO)2(
C5H4Rf17)2( -CO)2Rh(h5-C5H4Rf17)(CO)] (6)
m
-CO)] (5) and [Rh2(h5
-
yield a brown oil of 8. Yield: 636.9 mg (89%). UV–vis (C6H6):
(s), 351 (sh), 431 (sh) nm. IR (ATR, neat):
˜ 1930 (s, CO), 1242–1149
(s br, CF) cmꢀ1 1H NMR (300.1 MHz; C6D6):
5.01 (vt, 2H,
l 298
m
n
.
d
Storing a solution of [Rh(h5-C5H4Rf17)(CO)2] (3) in C6D6 in an
NMR tube at room temperature for 24 h led to the formation of 5
N = 23.7 Hz, C5H4), 4.93 (vt, 2H, N = 23.7 Hz, C5H4), 2.55 (m, 2H,
CH2CH2CF2), 2.38 (m, 2H, CH2CF2), 1.25 (m, 6H, PCH2), 0.81 (dt, 9H,
3JH,P = 16.6 Hz, 3JH,H = 7.6 Hz, CH3). 13C{1H} NMR (75.5 MHz; C6D6):
(ratio 3/5 = 10:1). IR (ATR, neat):
n
˜ 1966 (s, CO), 1832 (w, br,
m-CO)
cmꢀ1. 1H NMR (300.1 MHz, C6D6):
d
5.02 (vt, 4H, N = 2.1 Hz, C5H4),
d 110.3 (m, Cipso), 85.7 (m, CH), 84.8 (m, CH), 22.4 (dd, JC,P = 29 Hz,
4.82 (vt, 4H, N = 2.1 Hz, C5H4), 2.36 (m, 4H, CH2CH2CF2), 1.95 (m,
4H, CH2CH2CF2).
2JC,Rh = 3 Hz, PCH2), 19.6 (m, CH2CF2), 8.3 (s, CH3), the signals for
the CF2 and CF3 groups as well as the CO ligand and the CH2CH2CF2
After four weeks storing 3 and 5 in C6D6 in an NMR tube at room
group were not detected. 19F{1H} NMR (282.4 MHz; C6D6):
d
ꢀ81.3
temperature, a quantitative conversion into complex [Rh2(h5
-
(tm, 3F, 4JF,F = 10 Hz, CF3), ꢀ114.1 (m, 2F, CF2), ꢀ121.8 (m, 2F, CF2),
ꢀ122.1 (m, 4 F, CF2), ꢀ123.0 (m, 2F, CF2), ꢀ123.7 (m, 2F, CF2),
C5H4Rf17)2(
removal the solvent in vacuo led to the formation of 6. IR (ATR,
neat):
˜ 1950 and 1744 (m, CO), 1261–1150 (s br, CF) cmꢀ1
1H
NMR (300.1 MHz, THF-d8): 5.66 (vt, 2H, N = 2.0 Hz, C5H4), 5.59
m
-CO)2Rh(h5-C5H4Rf17)(CO)] (6) was observed. After
ꢀ126.5 (m, 2F, CF2). 31P{1H} NMR (121.5 MHz; C6D6):
d 44.84 (d,
n
.
JP,Rh = 186.0 Hz). MS (LIFDI, toluene), m/z: calcd. for
d
C
22H23F17OPRh+: 760; found: 760.
(vt, 4H, N = 2.0 Hz, C5H4), 5.48 (vt, 2H, N = 2.0 Hz, C5H4), 5.40 (vt,
4H, N = 2.0 Hz, C5H4), 2.65–2.59 (m, 6H, CH2CH2CF2), 2.54–2.42 (m,
4.7. Synthesis of [Rh(h5-C5H4Rf21)(CO)(PEt3)] (9) and [Rh(h5
C5H4Rf21)(13CO)(PEt3)] (90)
-
6H, CH2CF2). (300.1 MHz, C6D6):
5.01 (vt, 6H, N = 2.0 Hz, C5H4), 2.40 (m, 6H, CH2), 2.12 (m, 6H, CH2).
13C{1H} NMR (75.5 MHz, C6D6):
218.9 (m, CO), 110.13 (m, Cipso),
d 5.09 (vt, 6H, N = 2.0 Hz, C5H4),
d
[Rh(h5-C5H4Rf21)(CO)2] (4) (115.5 mg, 150
mol) was dis-
solved in 20 ml hexane and PEt3 (30 L, 200 mmol) was added
m
90.4 (m, CH), 90.18 (m, CH), 30.16 (m, CH2CF2), 18.69 (m,
CH2CH2CF2), the signals for the CF2 and CF3 groups were not
m
dropwise. The mixture was stirred and irradiated for 16 h. The
resulting suspension was filtered, all volatiles were removed in
vacuo from the filtrate and the residue lyophilized three times to
detected. 19F{1H} NMR (282.4 MHz, C6D6):
d
ꢀ81.4 (t, 9F,
4JF,F = 9.5 Hz, CF3), ꢀ114.5 (m, 6F, CF2), ꢀ121.9 (m, 6F, CF2),
ꢀ122.2 (m, 12F, CF2), ꢀ123.1 (m, 6F, CF2), ꢀ123.5 (m, 6F, CF2),
ꢀ126.6 (m, 6F, CF2).
yield a brown solid of 9. Yield: 123.9 mg (96%). UV–vis (C6H6):
297 (s), 355 (w), 412 (sh) nm. IR (ATR, neat): ˜ 1930 (s, CO), 1244–
1152 (s br, CF) cmꢀ1 1H NMR (300.1 MHz; C6D6):
5.01 (vt, 2H,
l
n
.
d
4.5. Synthesis of [Rh(h5-C5H4Rf13)(CO)(PEt3)] (7) and [Rh(h5
C5H4Rf13)(13CO)(PEt3)] (70)
-
N = 2.0 Hz, C5H4), 4.93 (vt, 2H, N = 2.0 Hz, C5H4), 2.56 (m, 2H,
CH2CH2CF2), 2.40 (m, 2H, CH2CF2), 1.25 (m, 6H, PCH2), 0.81 (dt, 9H,
3JH,P = 16.7 Hz, 3JH,H = 7.6 Hz, CH3). 13C{1H} NMR (75.5 MHz; C6D6):
[Rh(h5-C5H4Rf13)(CO)2] (2) (336.9 mg, 590
solved in 20 ml hexane and PEt3 (0.1 ml, 679
m
mol) was dis-
d
195.6 (dd, JC,Rh = 88 Hz, JC,P = 25 Hz, CO), 107.8 (m, Cipso), 85.7
2
m
mol) was added
(m, CH), 84.8 (m, CH), 35.8 (m, CH2CH2CF2), 22.4 (dd, JC,P = 29 Hz,
2JC,Rh = 3 Hz, PCH2), 19.6 (m, CH2CF2), 8.3 (s, CH3), signals for the
CF2 and CF3 groups were not detected. 19F{1H} NMR (282.4 MHz;
dropwise. The mixture was stirred and irradiated for 3 h. The
resulting suspension was filtered, all volatiles were removed in
vacuo from the filtrate and the residue lyophilized three times to
C6D6):
d
ꢀ80.9 (tt, 3F, 4JF,F = 10 Hz, 3JF,F = 2 Hz, CF3), ꢀ113.8 (m, 2F,
yield a brown oil of 7. Yield: 370.1 mg (95%). UV–vis (C6H6):
(s), 234 (s), 295 (s), 349 (w), 425 (sh br) nm. IR (ATR, neat):
˜ 1931
(s, CO), 1238–1145 (s br, CF) cmꢀ1 1H NMR (300.1 MHz; C6D6):
l
219
CF2), ꢀ121.6 (m, 10 F, CF2), ꢀ122.7 (m, 2F, CF2), ꢀ123.3 (m, 2F, CF2),
n
ꢀ126.1 (m, 2F, CF2). 31P{1H} NMR (121.5 MHz; C6D6):
d 44.8 (d,
.
d
JP,Rh = 185 Hz). MS (LIFDI, toluene), m/z: calcd. for C24H23F21OPRh+:
860; found: 860.
5.10 (vt, 2H, N = 2.0 Hz, C5H4), 5.02 (vt, 2H, N = 2.0 Hz, C5H4), 2.54
(m, 2H, CH2CH2CF2), 2.40 (m, 2H, CH2CF2), 1.25 (m, 6H, PCH2), 0.81
The synthesis of [Rh(h5-C5H4Rf21)(13CO)(PEt3)] (90) was done
analogously starting from a mixture of [Rh(h5-C5H4Rf21)(13CO)2]
(40) and [Rh(h5-C5H4Rf21)(CO)2] (4) (1:9) to give 90 and 9. Analytical
3
3
(dt, 9H, JH,P = 16.6 Hz, JH,H = 7.6 Hz, CH3). 13C{1H} NMR
2
(75.5 MHz; C6D6):
d
196.6 (dd, JC,Rh = 87 Hz, JC,P = 25 Hz, CO),
107.6 (vt, NC,C = 3 Hz, Cipso), 85.4 (vt, NC,C = 4 Hz, CH), 84.5 (d,
JC,C = 3 Hz, CH), 35.4 (t, JC,F = 22 Hz, CH2CF2), 22.1 (dd, JC,P = 29 Hz,
JC,Rh = 2 Hz, PCH2), 19.3 (m, CH2CH2CF), 8.0 (m, CH3), the signals for
the CF2 and CF3 groups were not detected. 19F{1H} NMR
data for 90: IR (ATR, neat):
n .
˜ 1882 (w, 13CO) cmꢀ1
31P{1H} NMR
2
(121.5 MHz; C6D6): 44.8 (d, JP,Rh = 185 Hz, JP,C = 26 Hz).
d
4.8. Synthesis of [Rh(h5-C5H4Rf17)(CO)(PRf133)] (10)
4
3
(282.4 MHz; C6D6):
d
ꢀ81.3 (tt, 3F, JF,F = 10 Hz, JF,F = 3 Hz, CF3),
ꢀ114.2 (m, 2F, CF2), ꢀ122.0 (m, 2F, CF2), ꢀ123.1 (m, 2F, CF2),
[Rh(h5-C5H4Rf17)(CO)2] (3) (100.5 mg, 150
m
mol) was dis-
mol)
ꢀ123.7 (m, 2F, CF2), ꢀ126.4 (m, 2F, CF2). 31P{1H} NMR (121.5 MHz;
solved in 5 ml C7F14 and P(CH2CH2C6F13 3 (160.0 mg, 150 m
)
C6D6):
d
44.8 (d, JP,Rh = 186 Hz). MS (LIFDI, toluene), m/z: calcd. for
was added. The mixture was stirred at 80 8C for 16 h. After
removing all volatiles in vacuo, the residue was washed with 2 ml
benzene, dried in vacuo and lyophilized three times to yield a
C
20H23F13OPRh+: 660; found: 660.
The synthesis of [Rh(h5-C5H4Rf13)(13CO)(PEt3)] (70) was done
analogously starting from [Rh(h5-C5H4Rf13)(13CO)2] (20) (172.0 mg,
300 mol) and PEt3 (60 L, 360 mol) in 15 ml pentane. Yield:
190.4 mg (96%). UV–vis (C6H6): 277 (s), 296 (s), 360 (w), 435 (sh
br) nm. IR (ATR, neat):
˜ 1883 (s, 13CO), 1261–1015 (s br, CF) cmꢀ1
1H, 13C{1H} and 19F{1H} NMR: see 7. 31P{1H} NMR (121.5 MHz;
C6D6):
44.8 (dd, JP,Rh = 186 Hz, 2JP,C = 25 Hz). MS (LIFDI, toluene),
m/z: calcd. for C19
13C)H23F13OPRh+: 661; found: 661.
yellow solid of 10. Yield: 46.3 mg (18%). UV–vis (C7F14):
261 (sh), 289 (sh), 327 (w), 366 (w sh) nm. IR (ATR, neat):
(w, CO), 1234–1140 (s br, CF) cmꢀ1 1H NMR (300.1 MHz; C7F14
capillary C6D6): 5.23 (vt, 2H, N = 2.1 Hz, C5H4), 5.03 (vt, 2H,
l
228 (s),
m
m
m
n
˜ 1965
l
.
,
n
.
d
N = 2.1 Hz, C5H4), 2.63 (m, 2H, CH2CH2CF2), 2.40 (m br, 8 H,
d
CH2CF2), 1.97 (m br, 6H, PCH2). 13C{1H} NMR (75.5 MHz; C7F14
,
2
(
capillary C6D6):
d
193.8 (dd, JC,Rh = 84 Hz, JC,P = 26 Hz, CO), the

F. Liebau et al. / Journal of Fluorine Chemistry 180 (2015) 192–200
199
other signals are overlapped by the signals of the solvent. 31P{1H}
NMR (121.5 MHz; C7F14, capillary C6D6): 45.2 (d, JP,Rh = 201 Hz).
the data can be obtained, free of charge, on application to CCDC, 12
Union Road, Cambridge CB2 1EZ, UK, via www.ccdc.cam.ac.uk/
data_request/cif (fax: +44 1223 336033 or e-mail: deposit@ccdc.
cam.ac.uk).
d
4.9. General procedure for dehydrogenation experiments in neat
alkanes
Acknowledgements
In a standard NMR tube the rhodium complex (0.2–1.07 mmol,
see Table 1) was dissolved in 0.2 ml alkane and the solution was
irradiated with 150 W Xe arc lamp for 1–7 days. C6D6 (0.4 ml) and
We acknowledge the Research Training Group GRK ‘‘Fluorine
as a Key Element’’ and the Cluster of Excellence ‘‘Unifying
Concepts in Catalysis’’, both funded by the Deutsche Forschungs-
gemeinschaft.
mesitylene (3
mL, 21.6 mmol) were added. The residual multiplet
signal of mesitylene at 6.69 ppm in the 1H NMR spectrum, caused
by three aromatic protons was used as an internal standard
reference. The signal for the olefinic protons of the generated
alkene was used to determine the conversion. When toluene was
generated, the aromatic signals were used for integration, too.
Organic products were characterized further from the C6D6
solutions by GC–MS.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.jfluchem.2015.
09.014.
4.10. General procedure for dehydrogenation experiments in C7F14
/
cycloalkane
References
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(2013) 6468–6475;
In a standard NMR tube the rhodium complex (20–200
mmol,
see Table 1) was dissolved in 0.3 ml C7F14 and 0.2 ml alkane was
added. The biphasic mixture was irradiated with 150 W Xe arc
lamp for 90 h. The fluoric phase was extracted with C6D6 (0.4 ml)
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and mesitylene (3
mL, 2.16 mmol) was added to the extract as
internal standard for quantification by 1H NMR spectroscopy.
Organic products were characterized further from the C6D6
solutions by GC–MS.
(e) F.C. Liu, A.S. Goldman, Chem. Commun. (1999) 655–656;
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4.11. Procedure for dehydrogenation experiment in a homogeneous
C7F14/cyclopentane mixture
In a standard NMR tube [Rh(h5-C5H4Rf21)(CO)(PRf3)] (11)
(7.8 mg, 4.3
mmol) was dissolved in 0.3 ml C7F14 and 0.2 ml
cyclopentane. The homogeneous solution was irradiated with
150 W Xe arc lamp for 48 h. C6D6 (0.4 ml) was added and a phase
separation of C7F14 (below) and hydrocarbon phase was observed.
Mesitylene (3
mL, 2.16 mmol) was added to the hydrocarbon phase
as an internal standard for quantification by 1H NMR spectroscopy.
Organic products were characterized further from the C6D6
solution by GC–MS.
(c) D. Duncan, E.G. Hope, K. Singh, A.M. Stuart, Dalton Trans. 40 (2011) 1998–
2005;
(d) L.C. St’astna, K. Auerova, J. Kvicala, J. Cermak, J. Organomet. Chem. 692
(2007) 1974–1982;
´
(e) J.A. Gladysz, D.P. Curran, I.T. Horvath, Handbook of Fluorous Chemistry,
4.12. Structure determination for 6
Wiley-VCH, Weinheim, Germany, 2004, p. 24;
(f) J.J.J. Juliette, I.T. Horvath, GladyszF J.A., Angew. Chem. 109 (1997) 1682;
(g) J.J.J. Juliette, I.T. Horvath, GladyszF J.A., Angew. Chem. Int. Ed. 36 (1997)
1610–1612;
Crystals of 6 were obtained by slow evaporation of a C6D6
solution stored 3 weeks. The data for X-Ray crystal structure
analysis were collected with a BRUKER D8 VENTURE area detector:
(h) J.A. Gladysz, Science 266 (1994) 55–56;
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Lo¨sungsmittel durch Iridium-Cyclopentadienyl-Komplexe, PhD thesis,
Humboldt-Universita¨t zu Berlin, 2014.
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[11] M.C. Asplund, P.T. Snee, J.S. Yeston, M.J. Wilkens, C.K. Payne, H. Yang, K.T.
Kotz, H. Frei, R.G. Bergman, C.B. Harris, J. Am. Chem. Soc. 124 (2002) 10605–
10612.
C
48H24F51O3Rh3, Mr = 1926.37, crystal dimensions 0.39 mm ꢃ
˚
¯
1; a = 8.0177(7) A, b =
0.08 mm ꢃ 0.03 mm, triclinic;
P
˚
˚
13.9874(11) A, c = 27.497(2) A,
a
= 102.986(4)8,
b
= 90.063(3)8,
3
calcd. = 2.199 g cmꢀ3
;
˚
g
= 104.094(4)8, Z = 2, V = 2909.3(4) A ,
r
u
max = 25.497; 67,220 reflections collected, 10,740 were unique
(Rint = 0.0999), = 0.71073), T = 90 K.
(Mo-K ) = 1.049 mmꢀ1
Final R1, wR2 values on all data: 0.1070, 0.2232; R1, wR2, GoF
m
(l
a
values for reflections with Io > 2
s
(Io): 0.0840, 0.2075, 1.013;
[12] (a) S. Trupia, T.E. Bitterwolf, W.E. Geiger, Organometallics 31 (2012) 6063–
6070;
residual electron density: +3.27/ꢀ1.82e Aꢀ3. Multi-scan absorp-
tion correction implemented in SADABS [28] was applied to the
data. The structure was solved by intrinsic phasing method
(SHELXT-2013) and refined by full-matrix least square procedures
based on F2 with all measured reflections (SHELXL-2013) with
anisotropic temperature factors for all non-hydrogen atoms [29].
All hydrogen atoms were added geometrically and refined by using
a riding model. The Crystallographic data have been deposited
with the Cambridge Crystallographic Data Centre as supplemen-
tary publication with a CCDC reference number 1405146. Copies of
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