Atom Transfer Radical Addition Catalyzed by Ruthenium-Arene Complexes Bearing a Hybrid Phosphine-Diene Ligand

Article abstract of DOI:10.1021/acs.organomet.7b00851

The synthesis and characterization of a series of arene ruthenium complexes bearing either (3,5-cycloheptadienyl)diphenylphosphine or (cycloheptyl)diphenylphosphine are reported. Upon irradiation or heating, all these complexes lose their arene ligand but then exhibit a different behavior depending on the nature of the phosphine ligand. (Cycloheptadienyl)phosphine complexes 1 and 3 give a cationic dinuclear Ru complex 5 for which the two Ru atoms are bridged by three chlorido ligands and flanked by two tridendate (cycloheptadienyl)phosphines. (Cycloheptyl)diphenylphosphine complexes 2 and 4 undergo arene exchange when toluene is used as solvent or degrade in dichloromethane. ATRA catalytic trials conducted in parallel with these complexes using CCl₄ and styrene as standard substrates, highlighted the deep impact of the dienyl moiety on the results. Under smooth conditions (UV irradiation or moderate heating), only (cycloheptyl)phosphine derivatives give Karasch adduct in satisfactory yields. Their performance was considerably improved by combining irradiation and heating. At higher temperature, cationic dinuclear complex 5 was revealed as active and robust, giving turnover numbers as high as 9700 when tetradecene and CCl₄ were used as substrates.

Full text of DOI:10.1021/acs.organomet.7b00851

Article
Cite This: Organometallics XXXX, XXX, XXX−XXX
Atom Transfer Radical Addition Catalyzed by Ruthenium−Arene
Complexes Bearing a Hybrid Phosphine−Diene Ligand
Florian Chotard, Raluca Malacea-Kabbara,* Ced
́
ric Balan, Ewen Bodio, Michel Picquet, Philippe Richard,
Miguel Ponce-Vargas, Paul Fleurat-Lessard, and Pierre Le Gendre*
Institut de Chimie Molec
́ ́ ́
ulaire de l′Universite de Bourgogne (ICMUB, UMR-CNRS 6302), Universite de Bourgogne
Franche-Comte, 9 av. A. Savary, 21078 Dijon, France
́
*
S Supporting Information
ABSTRACT: The synthesis and characterization of a series of
arene ruthenium complexes bearing either (3,5-
cycloheptadienyl)diphenylphosphine or (cycloheptyl)-
diphenylphosphine are reported. Upon irradiation or heating,
all these complexes lose their arene ligand but then exhibit a
different behavior depending on the nature of the phosphine
ligand. (Cycloheptadienyl)phosphine complexes 1 and 3 give a
cationic dinuclear Ru complex 5 for which the two Ru atoms
are bridged by three chlorido ligands and flanked by two
tridendate (cycloheptadienyl)phosphines. (Cycloheptyl)-
diphenylphosphine complexes 2 and 4 undergo arene
exchange when toluene is used as solvent or degrade in
dichloromethane. ATRA catalytic trials conducted in parallel
with these complexes using CCl and styrene as standard substrates, highlighted the deep impact of the dienyl moiety on the
4
results. Under smooth conditions (UV irradiation or moderate heating), only (cycloheptyl)phosphine derivatives give Karasch
adduct in satisfactory yields. Their performance was considerably improved by combining irradiation and heating. At higher
temperature, cationic dinuclear complex 5 was revealed as active and robust, giving turnover numbers as high as 9700 when
tetradecene and CCl were used as substrates.
4
INTRODUCTION
complex containing a phosphine with a pendant 1,3-butadiene
■
11,12
moiety.
Some interesting results were obtained for the
[
RuCl (arene)(PR )] complexes are known for promoting a
2 3
1
ATRA reaction. However, all our efforts to isolate or even
detect a chelated phosphine−diene complex failed at that time.
Thus, we were unable to prove our concept. We therefore
decided to use (3,5-cycloheptadienyl)diphenylphosphine in Ru-
promoted ATRA reaction since we previously clearly
established the chelating abilities of this hybrid phosphine
great variety of catalytic transformations, among which is atom
transfer radical addition (ATRA). This reaction, also called
Kharasch addition, allows the addition of a polyhalogenated
substrate to an olefin in a controlled manner. [RuCl (arene)-
2
3
,4
2
5
(
PR )] complexes are readily available and air-stable. They can
3
be activated by irradiation or simple heating which results in the
loss of the arene ligand.
particularly attractive from a practical point of view. Main
drawbacks are their relatively moderate activity in ATRA with
6
,7
These precatalysts are thus
13
diene ligand with rhodium. Herein, we present the synthesis
of (p-cymene)Ru complex 1 with cycloheptadienylphosphine
ligand (Figure 1). For the sake of comparison, we describe the
synthesis of Ru complex 2 with (cycloheptyl)-
diphenylphosphine ligand. This provides an exact analogue of
complex 1 which allows to estimate the contribution of the
dienyl moiety while avoiding other electronic and steric features
of the ligand. Since the catalytic activity results from the arene
release, we also targeted Ru complexes 3 and 4 with a more
labile, electron-poor ethyl benzoate ligand. Efforts toward the
identification of the species formed upon arene disengagement
8
,9
respect to the best Ru systems described to date and their
propensity to degrade upon prolonged reaction time, thus
limiting the turnover number (TON). The recurrent problem
of stability met with these catalysts may be explained by the
highly coordinatively unsaturated nature of the active species
formed once the 6π-electron arene ligand is released. Chelated
Ru complexes with phosphine−arene ligands have been
designed to address this issue. Unfortunately, they were
found inefficient for promoting mechanistically related atom
transfer radical polymerization (ATRP) reactions due to their
10
too high inertness. We hypothesized that the use of hybrid
phosphine−diene ligand instead might be a good compromise:
It should give stable but still active catalyst for ATRA reaction.
First, a set of catalytic trials were done using a (p-cymene)Ru
Special Issue: Organometallic Chemistry in Europe
Received: November 27, 2017
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.7b00851
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Article
Figure 1. Ruthenium complexes with cycloheptadienyl- or cyclo-
heptylphosphine ligands.
are described as well as assessment of the catalytic performance
of these complexes in ATRA.
RESULTS AND DISCUSSION
3,5-Cycloheptadienyl)diphenylphosphine has been obtained
via the catalytic hydrophosphination of 1,3,5-cycloheptatriene
■
(
with diphenylphosphine in the presence of n-BuLi according to
14
our previously described procedure. Its saturated analogue
was synthesized by reaction of bromocycloheptane with lithium
diphenylphosphide in diethyl ether at room temperature. The
(
cycloheptyl)phosphine was obtained as a white powder in 94%
Figure 2. ORTEP views of complexes 1−4 (hydrogen atoms are
omitted for clarity, except those on the cycloheptyl and cyclo-
heptadienyl rings). Selected distances (Å) and angles (deg) in 1−4
order: Ru−Ct 1.6906(10), 1.7114(15), 1.6949(8), 1.6964(14); Ru−P
2.3885(6), 2.3757(9), 2.3650(5), 2.3787(8); Ru−Cl1 2.4089(6),
yield. The synthesis of the Ru complexes 1−4 was then
accomplished by reacting the cycloheptadienyl- or cyclo-
heptylphosphine with 0.5 equiv of the respective dimer
6
[
Ru(η -arene)Cl ] (yields range between 90 and 95%). The
2
2
2
2
8
.4091(8), 2.4037(5), 2.3987(7); Ru−Cl2 2.3890(6), 2.4178(8),
.3959(4), 2.4042(7). Cl1−Ru−Cl2 88.86(2), 86.50(3), 89.391(16),
8.31(3); Cl1−Ru−Ct 123.29(4), 126.59(6), 125.05(3), 124.35(6);
1
13
complexes 1−4 were fully characterized by 1D NMR ( H, C,
P), 2D NMR (COSY, HSQC, HMBC), Elemental Analysis,
HRMS and IR spectroscopy. The P NMR spectra of
complexes 1−4 show one singlet at 21.3, 23.7, 25.4, and 27.7
ppm, respectively, downfield shifted of either 25 or 30 ppm
relatively to free phosphine depending on the arene ligand. The
3
1
3
1
Cl1−Ru−P 93.28(2), 90.50(3), 89.727(15); 85.29(3); Cl2−Ru−Ct
126.54(4), 124.82(6), 125.76(3), 124.96(6); Cl2−Ru−P 84.16(2),
87.71(3), 86.553(16), 93.66(3); Ct−Ru−P 128.47(4), 127.89(5),
1
28.02(3), 128.01(5).
1
H NMR spectra of 1 and 3 display only one multiplet between
5
.68 and 5.80 ppm for the four protons of the dienyl part, with
the appearance of a new signal at 100 ppm on the 31P NMR
spectrum. This difference in kinetics of arene decoordination
between darkness and daylight prompts us to study the
the same shape and in the same chemical shift range as those of
the free ligand. These results are indicative of the coordination
of the phosphorus atoms to the ruthenium metal and of the
noncoordinated state of the dienyl part of the
behavior of complex 3 under photoirradiation. CDCl solution
3
of complex 3 was irradiated by 150 W mercury lamp (Heraeus
TQ150 W) at room temperature, and reaction progress was
monitored by NMR. A total of 15 min of irradiation was
sufficient to see complete decoordination of the benzoate
(
cycloheptadienyl)phosphine. Suitable crystals for X-ray
diffraction studies of complexes 1−4 were obtained by vapor
diffusion techniques. ORTEP views of complexes 1−4 are
presented in Figure 2.
1
ligand in H NMR and the presence of only one peak at 100
In the four complexes, the arene ruthenium moieties present
a three-legged piano stool structure with structural parameters
similar to each other and within the range of those observed for
ppm on 31P NMR spectrum. Similar evolution was observed
with complex 1, but it required 2.5 h of irradiation time (Figure
3).
15
related [RuCl (arene)(PR )] structures. The cycloheptadien-
The reaction was next carried out from complex 3 at
preparative scale in Schlenk tube in CH Cl . One hour under
2
3
yl and cycloheptyl rings adopt a half-chairlike conformation and
chairlike conformation, respectively, and are oriented in an
antiperiplanar conformation with respect to the centroid of the
arene ring. In complexes 1 and 3, the diphenylphosphino group
is in pseudo-equatorial position on the cycloheptadienyl ring
leaving the dienyl moiety away from the Ru center.
2
2
irradiation was necessary to reach completion (Scheme 1). The
compound was isolated as brick-red powder after evaporation
of CH Cl and washing with diethyl ether. It was identified as a
2
2
cationic dinuclear complex 5 based on HRMS, elemental
analysis, X-ray diffraction study, and NMR spectroscopies.
Expectedly, 31P NMR spectrum of complex 5 displayed a
With the aim to check to what extent the dienyl part of the
cycloheptadienyl)phosphine can interact with the Ru center
1
(
single resonance at 100 ppm. H NMR spectrum recorded at
once the arene ligand is released, we have first studied the
behavior of 1 and 3 upon heating. Complex 3 with the more
253 K showed the disappearance of the signals of the benzoate
ligand and a split of the signals of the olefinic protons into two
multiplets at δ = 4.89 and 5.61 ppm of equal intensities, which
labile benzoate ligand was first heated at 50 °C in CDCl in a
3
1
4
Young NMR tube protected from light. H NMR spectrum
provides evidence of η -coordination of the cycloheptadienyl
registered after 16 h showed only 5% of free benzoate and no
moiety in solution (similar behavior was observed in Rh
31
13
change on P NMR spectrum. Prolonged heating for 8 h at 50
C under sunlight led to 60% of benzoate decoordination and
complexes). Vapor diffusion of pentane into CDCl solution
3
°
of complex (NMR sample) gave suitable crystals for X-ray
B
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pseudo axial position, allowing the formation of the Ru-
chelates. The bond lengths C3−C4 (1.407(3) Å), C4−C5
(
1.434(3) Å), and C6−C7 (1.400(3) Å) range between single
and double bound, and clearly indicate the π-back-bonding
character of Ru−diene bonds. The Ru−Cl distances are in the
expected range with Ru−Cl1 bond longer than Ru−Cl2 and
Ru−Cl3 bonds denoting stronger trans-effect of the phosphine
relative to olefins.
As mentioned above, photoirradiation of both complexes 1
and 3 using Heraeus TQ 150 W lamp with a broad emission
spectrum (230 to 580 nm) led to complex 5. With the aim to
get more insights into the photochemical behaviors of these
complexes, we measured their UV−visible spectra. Complexes
1
and 3 show absorption maxima at 369 and 362 nm,
respectively, while complex 5 gives band at 411 nm.
Consistently, UV−visible monitoring of CH Cl solution of
2
2
complexes 1 and 3 irradiated at 360 nm showed that both
complexes evolved toward 5 within a few minutes (see the
Supporting Information). We next calculated electronic
transitions for these systems using a time-dependent DFT
method (see the Experimental Section). The data nicely
reproduce the fact that complexes 1 and 3 absorb at similar
energies while the dimer 5 absorbs at lower energy (Table 1).
Figure 3. Time-course 31P{ H} NMR spectra (300 K) of a CDCl3
1
solution of 1 (right) and 3 (left) under irradiation (150 W Hg Lamp).
Scheme 1
Table 1. Theoretical Electronic Absorption Data Obtained
for the Studied Systems
calculated
experimental
diffraction study (Figure 4). The X-ray analysis confirmed the
complete loss of the benzoate ligand and the tridentate
5
a
λexp (nm)/ε (mol−1 L cm−1
)
λcalc (nm)
10 × f
1
3
5
399
392
421
2340
6730
1030
369/1544
362/2432
411/1652
a
f is the oscillator strength of the transition.
Moreover, while not being quantitative, our estimation of the
5
molar extinction coefficient (computed as 10 times the
oscillator strength) corresponds to a slightly allowed transition.
This is in agreement with the fact that all transitions have only a
partial metal to ligand charge transfer character (MLCT). In
complexes 1 and 3, the vacant orbitals involve the Ru−arene
and Ru−phosphine bonds, while the occupied ones exhibit
mainly a metal d block character (Figure 5 and Supporting
Information). Remarkably, for both complexes, the vacant
transition orbital is antibonding between the arene and the
ruthenium atom, while the occupied one indicates a bonding
interaction. This is in line with the fact that irradiating these
complexes around 360 nm will weaken the Ru−arene bond and
eventually lead to dissociation. In complex 5, because of the
resonance that takes place between the two metallic centers, the
electronic absorption cannot be described by a single pair of
natural transition orbitals but rather by a combination of them.
This is at the origin of the transition occurring at lower energy.
Combining the natural transition orbitals localizes the
transition on the left ruthenium atom, as shown on Figure 5
Figure 4. ORTEP views of complex 5 (hydrogen atoms and chloride
anion are omitted for clarity). Selected distances (Å) and angles (deg):
Ru1−Cl1 2.5280(5), Ru1−Cl2 2.4355(5), Ru1−Cl3 2.4285(5), Ru1−
P1 2.3001(6), Ru1−C3 2.266(2), Ru1−C4 2.145(2), Ru1−C5
2
.137(2), Ru1−C6 2.263(2), Ru1−Ct1 2.0910(19), Ru1−Ct2
.0865(16), P1−C1 1.829(2), C3−C4 1.407(3), C4−C5 1.434(3),
2
C5−C6 1.400(3); Cl1−Ru1−P1 168.802(19), Cl2−Ru1−P1
9
3.878(19), Cl3−Ru1−P1 92.748(19), Cl1−Ru1−Cl2 79.183(17),
Cl1−Ru1−Cl3 77.525(17), Cl2−Ru1−Cl3 80.474(17), C3−Ru1−P1
7
8.04(6), C3−Ru1−Cl1 111.40(6), C3−Ru1−Cl2 97.70(6), C3−
Ru1−Cl3 170.51(6), C3−Ru1−C4 37.06(9), C4−Ru1−P1 107.66(7),
C4−Ru1−Cl1 83.40(7), C4−Ru1−Cl2 116.71(7), C4−Ru1−Cl3
1
51.45(7).
(
bottom) or on the right one (see Supporting Information).
Complex 5 shows similarities with the cationic dinuclear
coordination of the cycloheptadienyl phosphine. It showed a
dinuclear cation in which the two Ru centers are connected by
three bridging chlorido ligands. The structure exhibits a 2-fold
axis passing through the midpoint of Cl2−Cl3 line and Cl1, the
two (cycloheptadienyl)phosphine ligands being oriented in a
cis-configuration. The two cycloheptadienyl rings adopt a
chairlike conformation with the diphenylphosphino group in
[LRu(μ-Cl) RuL] complexes reported by Gusev (L = POP
3
16
pincer ligand) and those reported by Baker and Brown (L =
17
bis(NHC) ligands) (Figure 6). The bimetallic complexes [(p-
2
cymene)Ru(μ-Cl )Ru(PR )(η -C H )] reported by Severin are
3
3
2
4
9f,j
also particularly relevant to this study. Beside the similarity of
structures, Severin’s complexes can be formed by heating a
solution of (p-cymene)RuCl PR with 0.5 equiv of the dimer
2
3
C
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and gave 96% yield of the addition product after 96 h (Table 2,
entries 1−3).
Table 2. Kharasch Addition of Carbon Tetrachloride to
a
Styrene under Irradiation
b
b
entry cat. solvent
time styrene conv. (%)
Kharasch add. (%)
c
1
2
3
4
5
6
7
8
9
1
1
1
1
3
4
5
1
2
3
4
5
1
2
3
4
5
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
DCM
96 h
96 h
96 h
4 h
4 h
4 h
4 h
4 h
4 h
4 h
4 h
4 h
4 h
10
96
13
10
52
2
1
96
2
c
c
d
d
d
d
d
d
2
44
2
Figure 5. Natural transition orbitals of complex 3 (top) and localized
Transition orbitals of complex 5 (bottom, see Supporting
Information). Contour threshold of 0.045 a.u. has been considered.
Color code: C in gray, P in orange, Cl in green, O in red, Ru in light
blue.
29
14
16
36
5
29
1
2
d
d
d
d
0
1
2
3
DCM
21
2
DCM
DCM
27
15
9
DCM
1
a
b
Conditions: [styrene] /[CCl ] /[catalyst] = 200:800:1. Deter-
0
4
0
0
c
mined by GC with dodecane as internal standard. Conditions: 23
d
°
C, irradiation: halogen 12 V/55 W. Conditions: 31 °C, irradiation:
Heraeus TQ 150 W.
The reactions were next conducted under irradiation with the
1
50 W mercury lamp and stopped after 4 h for comparative
purposes (Table 2, entries 4−8). Under these conditions,
cycloheptadienyl)phosphine ruthenium derivatives 1, 3, and 5
(
showed very low styrene conversions (maximum 14% with 5)
and only traces of the Kharasch adduct. In the same conditions,
Figure 6. Examples of μ-Cl dinuclear Ru complexes reported in the
literature.
3
(
cycloheptyl)phosphine derivatives 2 and 4 were more active
and allowed higher styrene conversions (52 and 29%,
respectively) and higher yields in the addition product (44
and 29%, respectively). The use of dichloromethane instead of
toluene (Table 2, entries 9−13) did not improve the catalytic
activities of 1, 3, and 5 and slightly decreased those of 2 and 4.
This first set of experiments showed that all three complexes
with (cyclopheptadienyl)phosphine 1, 3, and 5 are unable to
promote the Kharasch addition contrary to (cycloheptyl)-
phosphine Ru complexes. We assume that complex 5 is
unreactive because it is coordinatively saturated and irradiation
6
[
Ru(η -arene)Cl ] under ethylene pressure. These compounds
2
2
revealed among the best precatalysts in ATRA reaction
9
f,j
described so far. A plausible mechanism of formation of
these complexes starts with the arene decoordination to
generate a coordinatively unsaturated [RuCl PR ] species
which next reacts with the Ru dimer and ethylene. In the
case of complex 3, we presume that after decoordination of the
arene ligand, (cycloheptadienyl)phosphine flips and forms a
6e-chelate [{(η -C H )PPh -κP}RuCl ], which subsequently
2
3
4
1
is not sufficient to open a coordination site on Ru for CCl
4
7
9
2
2
dimerizes to give the dinuclear cation 5.
activation due to chelate effect. We presume that, under
catalytic conditions, both (cycloheptadienyl) complexes 1 and 3
are converted in the cationic dinuclear complex 5 which de facto
put at the same level the three complexes. To verify this
hypothesis, we recorded NMR spectra of toluene and
We next investigated the ability of complexes 1−5 to catalyze
Kharasch addition of CCl to styrene. Considering the ease of
4
arene-Ru bond cleaving under light irradiation, we first studied
the impact of light on (arene)Ru-catalyzed ATRA reaction. The
reactions were conducted in toluene at room temperature using
dichloromethane solutions of complex 3 (0.01 mmol), CCl
4
0
.5 mol % ruthenium (0.5 mol % complexes 3 and 4 or 0.25
(30 equiv) and styrene (20 equiv) after 4 h under 150 W
mercury lamp irradiation at room temperature (Figure 7). In
mol % complex 5). After 24 h in the dark, none of the three
complexes tested (3−5) showed conversion in the Kharasch
adduct. When the reaction mixture was allowed to evolve under
natural light for 72 h, (cycloheptadienyl)phosphine complexes
31
CD Cl , P NMR spectrum displayed the signal of complex 5
2 2
at 100 ppm. In toluene, we observed the formation of a
precipitate which was also further identified as 5. In both cases,
1
3
and 5 showed no improvement. Conversely, (cycloheptyl)-
H NMR spectra showed that only traces of Kharasch addition
phosphine complex 4 gave 89% yield in Kharasch addition. A
similar trend was observed using 12 V/55 W halogen lamp as
irradiation source. Among complexes 3−5, only 4 was active
products are formed in these conditions. These results confirm
our hypothesis and demonstrate that CCl does not react with
4
18
the butadiene moiety of the hybrid phosphine.
D
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Table 3. Kharasch Addition of Carbon Tetrachloride to
a
Styrene in Absence of Light at Different Temperatures
b
b
entry cat. temperature (°C) styrene conv. (%)
Kharasch add. (%)
1
2
3
4
5
6
7
8
9
1
1
2
3
4
5
1
2
3
4
5
60
60
60
60
60
85
85
85
85
85
22
1
26
13
1
16
100
24
96
7
35
2
100
22
88
1
c
c
100
48
98
0
26
a
b
[
styrene] /[CCl ] /[catalyst] = 200:800:1. Determined by GC
0 4 0 0
with dodecane as internal standard after 3 days heating in absence of
c
light. Reaction already completed after 1 day.
Figure 7. 31P NMR and 1H NMR of complexes 3 (top) and 4
(
bottom) in CD Cl2 in the presence of styrene and CCl4 under
2
irradiation with 150 W Hg Lamp, 4 h, r.t.
complexes series can be explained by the fact that under
heating the dissociation of the arene ligand is much slower than
under irradiation and becomes a limiting factor.
Aware of this limitation, we next tried to improve the
catalytic performances of complexes 2 and 4 using simulta-
neous heating and irradiation (Hg lamp). Time course of
For comparative purposes, we performed similar experiments
with complex 4 under irradiation. In absence of the substrate,
3
1
P NMR spectrum of CD Cl solution of complex 4 displayed
2
2
no peak at all and only noncoordinated ethyl benzoate signals
ATRA between styrene and CCl catalyzed by complexes 2 and
4
1
were visible by H NMR. In presence of ATRA substrates (4:
4
under irradiation at 25, 60, and 85 °C are presented in Figure
3
1
0
.01 mmol, CCl : 30 equiv, and styrene: 20 equiv), P NMR
4
8. For comparative purpose, conversions obtained at 60 °C in
the absence of light are also reported. Sampling after 1, 2, and 4
h showed that simultaneous irradiation and heating boost the
performances of both complexes. After only 1 h under
irradiation at 85 °C, the yield in Kharasch addition product
spectrum displayed several peaks ranging from 50 to 80 ppm,
1
and H NMR analysis showed 65% Kharasch addition product
(Figure 7). UV exposure of toluene solution of 4 gave a
31
different result. In the absence of substrates, the P NMR
spectrum showed complete transformation of 4 (26.2 ppm) to
6
[
(η -toluene)RuCl {(cycloheptyl)PPh }] 6 which presents a
2
2
signal at 27.8 ppm. This product was isolated, and the XRD
analysis of crystals confirmed the ethyl benzoate replacement
by toluene (see the Supporting Information). In presence of
ATRA substrates (4: 0.01 mmol, CCl : 30 equiv, and styrene:
4
20 equiv), similar transformation of 4 to 6 was observed, giving
also Kharasch addition products in 80% conversion. This result
might appear surprising at first sight because complex 6 is
capped by a toluene ligand. Nevertheless, as the irradiation is
maintained throughout the reaction, active species can be
restored continuously.
We studied the performances in Kharasch addition of
complexes 1−5 under heating in the absence of light (Table
3, entries 1−5). The results under irradiation conditions and
heating followed the same trend, but differences emerged
between complexes of the same series. After 3 days at 60 °C in
toluene, only (cycloheptyl)phosphine benzoate ruthenium
complex 4 allowed total conversion of styrene with very good
selectivity toward Kharasch adduct (96% yield, Table 3 entry
4
). Other ruthenium complexes 1−3 and 5 gave very low
styrene conversion (16−26%) with a maximum of 13% yield in
Kharasch product with complex 2. In toluene at 85 °C, both
(
cycloheptyl)phosphine Ru complexes 2 and 4 gave Kharasch
adduct in good yields (88% and 98% yield, respectively). At 85
C, (cycloheptadienyl)phosphine ruthenium derivatives 1 and 3
Figure 8. Time course of Kharasch addition of CCl to styrene with
4
°
ruthenium complexes 2 (blue triangles) and 4 (pink squares) at
different temperatures under 150 W Hg Lamp irradiation (continuous
lines) or in absence of light (dotted lines) at 60 °C. Conditions:
[styrene] /[CCl ] /[catalyst] = 200:800:1, solvent: toluene.
remained inactive, while complex 5 showed a significant
improvement in performance (Table 3, entry 10). These
differences within cycloheptyl- and cycloheptadienyl Ru
0
4
0
0
E
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Organometallics
Article
using complex 4 reached 91%, whereas the same complex gave
investigated ATRA reaction of alternative substrates like 1-
9% yield at 25 °C and 2% at 60 °C in the dark.
octene and tetradecene with CCl using complex 5 at an olefin/
4
Concerning (cycloheptadienyl)phosphine Ru complexes 1
[Ru] ratio of 10 000. This gave Kharasch adduct in 95 and 98%
yields, respectively, after 48 h at 147 °C (TON = 9500 and
9700, respectively). With analogous substrates, monometallic
and 3, it was clear that light irradiation was not sufficient to
generate active species and/or to maintain them alive.
However, we have shown that complex 5 can promote ATRA
[RuCl
TON ranging from 150 to 280.
[(p-cymene)Ru(μ-Cl )Ru(PR
(arene)(PR
)] complexes described by Demonceau gave
2
3
2b,11
between styrene and CCl at 85 °C but only with moderate
The bimetallic complexes
)] reported by Severin
4
2
activity. NMR experiments conducted with 5 showed that it
3
3
)(η -C
2
H
4
was stable in C D Br solution even after a prolonged time at
reached TON of 1500 but needs Mg as a cocatalyst for
6
5
II
III
9j
147 °C. We therefore thought that this robustness may allow to
regenerating Ru from the Ru active species. The best
complex [Cp*RuCl (PPh )] reported so far reach a TON of
3.200 for styrene and 44.500 for 1-hexene but requires the use
improve the TON of the catalyst by authorizing ATRA
reactions at elevated temperatures. To test this hypothesis, we
2
3
1
9g
of AIBN as cocatalyst. These last values are clearly superior to
those obtained in this study but with complex 5, no cocatalyst is
needed.
carried out addition of CCl to styrene in bromobenzene at 147
4
°
C with only 0.1 mol % ruthenium complexes 3−5 (1:1000
ratio [Ru]/styrene) without any light source (Figure 9).
CONCLUSION
■
(
In summary, we have described the synthesis of a series of
arene)RuCl PR3 complexes with (cycloheptadienyl)- and
2
(
cycloheptyl)diphenylphosphine. Upon irradiation or heating
in toluene, all these complexes lose the arene ligand but then
behave differently depending on the nature of the phosphine
ligand. (Cycloheptadienyl)phosphine complexes 1 and 3 give a
cationic dinuclear Ru complex 5 bridged by three chlorido
ligands and flanked by two tridendate (cycloheptadienyl)-
phosphine, whose structure has been confirmed by X-ray
diffraction study. Complexes 2 and 4 undergo arene exchange
with toluene. ATRA catalytic trials conducted in parallel with
these complexes using CCl and styrene as standard substrates
4
highlighted the deep impact of the dienyl moiety on the results.
Under smooth conditions (UV irradiation or moderate
heating), only (cycloheptyl)phosphine derivatives give Karasch
adduct in satisfactory yields. Their performance were further
considerably improved by combining irradiation and heating
conditions. At a higher temperature, the cationic dinuclear
Figure 9. Kharasch addition with complexes 3−5 in bromobenzene at
1
1
47 °C (dark); first cycle: [styrene] /[CCl ] /[catalyst]
=
0
4
0
0
000:4000:1 (18 h); second cycle: adding [styrene]/[CCl ]/[catalyst]
complex 5 revealed active and robust, giving turnover numbers
4
4
=
1000:4000:0 (22 h).
close to 10 when octene (or tetradecene) and CCl were used
4
as substrates.
After 18 h, all three complexes gave almost total conversions
of styrene and good yields in Kharasch adduct. To test further
the stability of the catalysts, a second cycle was run by adding
the same amount of substrates to the reaction mixture. After
another 22 h at 147 °C, complex 4 showed reduced activity
giving only small amount of Kharasch adduct. In contrast,
complexes 3 and 5 were still active, with the latter showing
almost the same performances than during the first cycle.
Lower catalyst loading of 5 has been also tested (Table 4). The
reaction with 5 using a styrene/[Ru] ratio of 5000 gave 74%
yield in Kharasch addition product (TON= 3700). We next
EXPERIMENTAL SECTION
General Considerations. All reactions, except when indicated,
were carried out under an atmosphere of purified argon using
conventional Schlenk techniques. DCM, diethyl ether, THF, toluene,
■
6
and pentane were dried using a MBRAUN SPS 800. [(η -p-
1
9
6
20
cymene)RuCl ] ,
[(η -ethyl benzoate)RuCl ] ,
and (3,5-
2
2
2 2
1
4
cycloheptadienyl)diphenylphosphine have been synthesized accord-
ing to literature procedure. Other reagents were commercially available
and used as received from suppliers unless otherwise specified.
Analyses were performed at the “Plateforme d’Analyses Chimiques et
̀ ́ ́
de Synthese Moleculaire de l’Universite de Bourgogne”. The identity
and purity (≥95%) of the compounds were unambiguously established
using elemental analyses, multinuclear NMR spectroscopy, X-ray
diffraction analysis, high-resolution mass spectrometry, and infrared
spectroscopy. Elemental analyses were obtained on a Flash EA 1112
Table 4. Kharasch Addition of Carbon Tetrachloride to
Olefins at Low Catalyst Loading of 5
a
S/[Ru]
atyrene conv. Kharasch add.
1
13
d
d
CHNS-O Thermo Electron Flash instrument. NMR spectra ( H, C,
and 31P) were recorded on Bruker 300 Avance III or Bruker 500
Avance III spectrometers. All acquisitions, except when indicated, were
performed at 300 K. Chemical shifts are quoted in parts per million
entry
olefin
styrene
ratio
(%)
(%)
TON
b
1
5000
10000
10000
96
96
98
74
95
97
3700
9500
9700
c
2
1-octene
c
1
13
31
1
3
1-tetradecene
(δ) relative to TMS (for H and C) or 85% H PO (for P). For H
3 4
and 13C spectra, values were determined by using solvent residual
signals (e.g., CHCl in CDCl ) as internal standards. For P, 85%
a
31
Conditions: reaction in bromobenzene (4 mL) at 147 °C for 48 h in
3
3
b
the absence of light. Conditions: styrene (10 mmol), CCl4 (40
mmol), 5 (0.001 mmol); Conditions: styrene (20 mmol), CCl (80
mmol), 5 (0.001 mmol: 0.002 mmol [Ru]); Determined by GC with
H PO was used as an external standard. The coupling constants (J)
3 4
c
are reported in Hertz (Hz). Multiplicity abbreviations: s = singlet, bs =
broad singlet, d = doublet, t = triplet, q = quartet, dd = doublet of
4
d
1
13
dodecane as internal standard.
doublets. Assignment of H and C signals (when possible) was done
F
DOI: 10.1021/acs.organomet.7b00851
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
through the use of DEPT and 2D experiences (COSY, HSQC). High-
resolution mass spectra were recorded on a Thermo LTQ Orbitrap XL
ESI-MS (electrospray ionization mass spectrometry). Infrared spectra
were recorded on a Bruker Vertex 70v spectrophotometer fitted with a
Globar MIR source, a Ge/KBr (MIR) or silicon (FIR) beam splitter, a
DLaTGS detector, and a diamond ATR module. UV−visible
absorption spectra were recorded on a JASCO V630BIO spectrom-
eter. The irradiation experiments were performed by using a JASCO
FP8500 spectrofluorometer instrument.
C H Cl PRu: C, 59.59; H, 5.69. Found: C, 59.59; H, 5.81. HR-MS
29
33
2
+
+
(ESI-pos): calcd for [C H OPRu] [M − 2Cl + OMe] : 545.15418.
30
36
1
Found: 545.15414 (−0.1 ppm). H NMR (500 MHz, CD Cl ): δ
2
2
(ppm) = 7.94−7.87 (m, 4H, o-Ph), 7.56−7.43 (m, 4H + 2H, m-Ph, p-
Ph), 5.80−5.68 (m, 4H, diene), 5.03−4.96 (m, 2H, MeC CH), 4.89
q
3
i
(d, J = 6.1 Hz, 2H, PrC CH), 3.42−3.32 (m, 1H, PCH), 3.03−
2.95 (m, 2H, PCHCH H ), 2.57 (hept, J = 6.9 Hz, 1H, CH Pr),
HH
q
3
i
a
b
HH
3
1.81 (s, 3H, Me), 1.72−1.63 (m, 2H, PCHCH H ), 1.02 (d, J = 7.0
a
b
HH
i
13
1
Hz, 6H, CH Pr). C{ H} NMR (126 MHz, CD Cl ): δ (ppm) =
3
2
2
134.1 (d, 2JCP = 8.3 Hz, o-Ph), 133.1 (d, 1JCP = 39.1 Hz, i-Ph,
X-ray Experimental Procedure. Suitable crystals for X-ray
analysis were selected and mounted on a mylar loop with oil on a
Bruker APEX-II CCD diffractometer. Crystals were kept at 115 K
3
overlapping with PCHCH CHCH), 133.0 (d,
J
= 14.5 Hz,
2
CP
4
PCHCH CHCH, overlapping with i-Ph), 130.9 (d, J = 2.6 Hz, p-
2
CP
21
3
during data collections. Using Olex2, the structures were solved with
Ph), 128.5 (d, J = 9.1 Hz, m-Ph), 125.7 (s, PCHCH CHCH),
CP
2
22
i
2
the ShelXT structure solution program using Direct Methods and
1
8
(
09.7 (s, PrC ), 95.3 (s, MeC ), 91.2 (d, J = 4.0 Hz, MeC CH),
q q CP q
23
2
i
1
refined with the XL refinement package using Least Squares
minimization against |F|. In 2, the cycloheptyl group was found to
be disordered, and two conformations were refined with occupation
factors converged to 0.55/0.45. For 5, one of the four chloroform
solvate molecules present in the asymmetric unit was found to be
disordered over two positions, and both components were refined with
occupation factors converged to 0.54/0.46.
5.7 (d, J = 5.6 Hz, PrC CH), 35.1 (d, J = 19.1 Hz, PCH), 33.7
s, PCHCH ), 30.6 (s, CH Pr), 22.1 (s, CH Pr), 17.8 (s,
Me). P{ H} NMR (202 MHz, CD Cl ): δ (ppm) = 21.3 (s).
Selected IR bands (ATR): wavenumber (cm ) = 290 (νRu−Cl).
RuCl (η -p-cymene)(cycloheptyldiphenylphosphine-κP) (2).
RuCl (η -p-cymene)] (1 equiv, 520 mg, 0.849 mmol) and
CP
q
CP
i
i
2
3
31
1
2
2
−1
6
2
6
[
2
2
cycloheptyldiphenylphosphine (2.2 equiv, 528 mg, 1.87 mmol) in
toluene (15 mL) were stirred at room temperature for 16 h in the
dark. The solvent was evaporated. The residue was triturated and
washed with pentane and dried to give 2 as an orange powder (902
Computational Details. All DFT and TD-DFT calculations were
24
carried out with the Gaussian09 code, tightening self-consistent field
−10
convergence thresholds (10 a.u.). Geometry optimizations without
symmetry constraints and the corresponding frequency calculations
mg, 90%). Elemental Analysis: calcd for C H Cl PRu: C, 59.18; H,
25
29 37
2
were conducted with a LANL2TZ(f) basis set and a pseudopotential
6
.34. Found: C, 59.02; H, 6.32. HR-MS (ESI-pos): calcd for
2
6−28
for the Ru atom and a 6 31+G(d) basis set for all other atoms.
+
+
[
C H ClPRu] [M − Cl] : 553.13594. Found: 553.13416 (−3.2
29
29 37
The hybrid functional PBE0 was selected given its good performance
in previous DFT studies involving ruthenium-containing systems.
1
ppm). H NMR (500 MHz, CD Cl ): δ (ppm) = 7.95−7.87 (m, 4H,
3
0
2
2
o-Ph), 7.52−7.43 (m, 4H + 2H, m-Ph, p-Ph), 4.97−4.94 (m, 2H,
Vertical excitations were computed with TD-DFT using a larger basis
set (i.e., 6-311++G(d,p) for H, C, N, O, and Cl and LANL2TZ(f)
basis sets and pseudopotential for the metal). TD-DFT calculations
were performed with the PBE0 functional. For each complex, 24 states
were considered. The solvent effects of dichloromethane were
3
i
MeC CH), 4.86 (d, J = 6.1 Hz, 2H, PrC CH), 3.18−3.07 (m, 1H,
q
HH
q
3
i
PCH), 2.58 (hept, J = 7.0 Hz, 1H, CH Pr), 2.30−2.19 (m, 2H,
HH
PCHCH H ), 1.80 (s, 3H, Me), 1.53−1.45 (m, 4H, cycloheptyl),
a
b
1
.44−1.37 (m, 2H, cycloheptyl), 1.37−1.27 (m, 2H, cycloheptyl), 1.04
d, J = 7.0 Hz, 6H, CH3 Pr), 0.80−0.94 (m, 2H, PCHCH H ).
3
i
(
3
1,32
HH
a
b
included according to the Polarizable Continuum Model.
This
13
1
2
C{ H} NMR (126 MHz, CD Cl ): δ (ppm) = 134.2 (d, J = 8.1
2
2
CP
procedure allows to reproduce the UV absorption spectrum of our
complexes, as shown in the Supporting Information. All orbital
1
4
Hz, o-Ph), 133.9 (d, J = 38.4 Hz, i-Ph), 130.6 (d, J = 2.6 Hz, p-
Ph), 128.3 (d, JCP = 9.1 Hz, m-Ph), 109.4 (s, C
CP
CP
3
i
33
q
Pr), 95.1 (s, C
Me),
q
isosurfaces have been plotted with the Chemcraft code considering a
contour threshold of 0.045 au. The orbital transitions of selected
excited states were characterized using the natural transition orbital
2
2
i
9
3
1.0 (d, J = 3.9 Hz, MeC CH), 85.7 (d, J = 5.7 Hz, PrC CH)
5.8 (d, J = 20.6 Hz; PCH), 30.6 (s, CH Pr), 30.2 (d, J = 1.8
CP
q
CP
q
1
i
3
CP
CP
2
3
4
Hz, PCHCH
2
CH
2
), 28.6 (d, JCP = 13.4 Hz, PCHCH
2
), 28.0 (s,
(
NTO) method. The LANL2TZ (f) basis set and pseudopotentials
i
31
1
35
PCHCH CH CH ), 22.1 (s, CH Pr), 17.8 (s, Me). P{ H} NMR
2
2
2
3
were taken from the EMSL Basis Set Exchange Web site.
(
202 MHz, CD Cl ): δ (ppm) = 23.7 (s). Selected IR bands (ATR):
2 2
Cycloheptyldiphenylphosphine. Diphenylphosphine (1 equiv,
.10 g, 11.3 mmol) was diluted in diethyl ether (10 mL). n-
−
1
wavenumber (cm ) = 293 (νRu−Cl).
2
6
RuCl (η -BzOEt)[(3,5-cycloheptadienyl)diphenylphosphine-
2
Butyllithium (1 equiv, 11.3 mmol, 2.5 M in hexanes, 4.52 mL) was
slowly added, and the resulting mixture was stirred for 1 h; a yellow
color was observed. Bromocycloheptane (1 equiv, 11.3 mmol, 2.00 g)
was slowly added, and the reaction mixture was stirred 16 h. The
volatiles were evaporated. The residue was extracted with pentane (3
6
κP] (3). [RuCl (η -BzOEt)] (1 equiv, 536 mg, 0.833 mmol) and
2
2
cycloheptadyenyldiphenylphosphine (2.2 equiv, 510 mg, 1.83 mmol)
in toluene (15 mL) were stirred at room temperature for 16 h in the
dark. The solvent was evaporated. The residue was triturated and
washed with pentane and dried to give 3 as an orange solid (930 mg,
×
20 mL). The filtrate was concentrated to give the product as a white
9
0%). Elemental Analysis: calcd for C H Cl O PRu: C, 56.01; H,
28 29 2 2
solid (2.99 g, 94%). Elemental Analysis: calcd for C H P: C, 80.82;
19
23
4
.87. Found: C, 56.04; H, 5.13. HR-MS (ESI-pos): calcd for
H, 8.21. Found: C, 80.96; H, 8.35. HR-MS (ESI-pos): calcd for
+
+
+
+
1
[C28H29Cl O PRuNa] [M + Na] : 623.02179. Found: 623.02230
2 2
[
C H P] [M + H] : 283.16101. Found: 283.16061 (−1.4 ppm). H
19
24
1
(
4
0.8 ppm). H NMR (500 MHz, CD CN): δ (ppm) = 7.93−7.81 (m,
3
NMR (500 MHz, CD Cl ): δ (ppm) = 7.53−7.47 (m, 4H, o-Ph),
2
2
H, o-Ph), 7.59−7.53 (m, 2H, p-Ph), 7.48−7.55 (m, 4H, m-Ph), 6.23
7
1
1
.35−7.27 (m, 4H + 2H, m-Ph, p-Ph), 2.46−2.38 (m, 1H, PCH),
.76−1.66 (m, 4H, cycloheptyl), 1.65−1.59 (m, 2H, cycloheptyl),
.58−1.45 (m, 4H, cycloheptyl), 1.44−1.33 (m, 2H, cycloheptyl).
3
(
5
d, J = 6.5 Hz, 2H, o-BzOEt), 5.80−5.68 (m, 4H, diene), 5.44−
HH
3
.36 (m, 1H, p-BzOEt), 4.85 (t, J = 5.6 Hz, 2H, m-BzOEt), 4.32 (q,
HH
3
1
3
1
1
JHH = 7.1 Hz, 2H, OCH CH ), 3.49−3.38 (m, 1H, PCH), 2.97−2.86
2
3
C{ H} NMR (125.8 MHz, CD Cl ): δ (ppm) = 138.8 (d, J = 15.5
Hz, i-Ph), 134.0 (d, J = 19.1 Hz, o-Ph), 129.0 (s, p-Ph), 128.7 (d,
JCP = 6.9 Hz, m-Ph), 35.8 (d, J = 9.6 Hz, PCH), 31.4 (d, J
8.4 Hz, PCHCH ), 29.0 (s, PCHCH CH CH ), 28.6 (d, J = 12.4
2
2
CP
3
2
(m, 2H, PCHCH H ), 1.79−1.68 (m, 2H, PCHCH H ), 1.33 (t, J
= 7.1 Hz, 3H, OCH CH ). C{ H} NMR (125.8 MHz, CD CN): δ
a
b
a
b
HH
CP
13 1
3
1
2
2
3
3
=
CP
CP
2
3
(ppm) = 165.0 (s, CO), 134.6 (d, JCP = 8.3 Hz, o-Ph), 133.5 (d,
1
2 2 2 2 CP
3
1
31
1
J
= 14.7 Hz, PCHCH CHCH), 133.0 (d, J = 42.5 Hz, i-Ph),
CP
2
CP
Hz, PCHCH CH ). P{ H} NMR (202.4 MHz, CD Cl ): δ (ppm) =
2
2
2
2
4
3
1
31.9 (d, J = 2.6 Hz, p-Ph), 129.3 (d, J = 9.6 Hz, m-Ph), 126.3
−
2.8 (s).
CP CP
2
6
(s,PCHCH CHCH), 96.6 (d, J = 3.3 Hz, o-BzOEt), 91.2 (s, p-
R u C l ( η - p - c y m e n e ) [ ( 3 , 5 - c y c l o h e p t a d i e n y l ) -
2
CP
2
2
2
6
BzOEt), 87.3 (d, J = 7.8 Hz, p-BzOEt), 85.4 (d, J = 2.7 Hz, m-
diphenylphosphine-κP] (1). [RuCl (η -p-cymene)] (1 equiv, 524
CP CP
2
2
1
mg, 0.856 mmol) and cycloheptadienyldiphenylphosphine (2.2 equiv,
24 mg, 1.88 mmol) in toluene (15 mL) were stirred at room
BzOEt), 63.1(s, OCH
2
CH
), 14.9 (s, OCH CH ). P{ H} NMR (202.4
2 3
3
), 36.3 (d, JCP = 20.1 Hz, PCH), 34.3 (d,
2
31
1
5
J
CP = 1.4 Hz, PCHCH
2
temperature for 16 h in the dark. The solvent was evaporated. The
residue was triturated and washed with pentane and dried to give 1 as
an orange solid (940 mg, 94%). Elemental Analysis: calcd for
MHz, CD CN): δ (ppm) = 25.4 (s). Selected IR bands (ATR):
3
−
1
wavenumber (cm ) = 300 (νRu−Cl), 1111 (νO−C−C), 1272
(ν ), 1708 (ν ).
C−C(O)−O
CO
G
DOI: 10.1021/acs.organomet.7b00851
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
6
6
RuCl (η -BzOEt)(cycloheptyldiphenylphosphine-κP) (4). [η -
glovebox and then irradiated with 150 W mercury lamp (Heraeus TQ
150 W) or heated to the desired temperature under light protection.
The styrene conversion and the yield of the Kharasch adduct were
determined by GC after calibration with respect to the internal
standard. All solvents and reagents were dried and kept under argon
prior to use. The sampling of the reaction mixture was made in the
glovebox under argon. GC method: 100 °C, 10°/min, 220 °C (10
2
(
Ethyl benzoate)RuCl2]2 (1 equiv, 533 mg, 0.827 mmol) and
cycloheptyldiphenylphosphine (2.2 equiv, 514 mg, 1.82 mmol) in
toluene (15 mL) were stirred at room temperature for 16 h in the
dark. The solvent was evaporated. The residue was triturated and
washed with pentane, and dried to give 4 as an orange solid (950 mg,
5%). Elemental Analysis: calcd for C H Cl O PRu: C, 55.63; H,
.50. Found: C, 56.13; H, 5.52. HR-MS (ESI-pos): calcd for
9
5
[
(
4
28 33 2 2
−1
min), column flow: 1 mL mn , split ratio:100, column: QUADREX
+
+
C H Cl O PRuNa] [M + Na] : 627.05309. Found: 627.05280.
60329B, length 30.0 m, inner diameter 0.25 mm, film thickness 0.25
μm.
28
33
2
2
1
−0.5 ppm). H NMR (500 MHz, CD Cl ): δ (ppm) = 7.91−7.84 (m,
2
2
3
H, o-Ph), 7.54−7.46 (m, 4H + 2H, m-Ph, p-Ph), 6.28 (d, J = 6.6
HH
Hz, 2H, o-BzOEt), 5.30−5.31 (m, 1H, p-BzOEt, overlapping with
ASSOCIATED CONTENT
Supporting Information
■
3
CD Cl residual signal), 4.71 (t, J = 5.8 Hz, 2H, m-BzOEt), 4.36
2
2
HH
*
S
3
(
2
q, J = 7.1 Hz, 2H, OCH CH ), 3.26−3.17 (m, 1H, PCH), 2.22−
HH
2
3
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.7b00851.
.13 (m, 2H, PCHCH H ), 1.56−1.45 (m, 4H, cycloheptyl over-
a
b
lapping with H O signal), 1.45−1.30 (m, 4H, cycloheptyl overlapping
2
with OCH CH signal), 1.38 (t, 3
J
= 7.1 Hz, 3H, OCH CH
2
3
HH 2 3
overlapping with cycloheptyl signal), 1.06−0.95 (m, 2H, PCHCH H ).
1H, 13C, and 31P NMR spectra of complexes 1−6, UV
a
b
1
3
1
C{ H} NMR (126 MHz, CD Cl ): δ (ppm) = 164.4 (s, CO),
2
2
visible spectra of complexes 1−5, evolution of UV−
visible spectra of compounds 1 and 3 under irradiation at
360 nm, tables of crystal data for complexes 1−6 and
calculated transition orbitals of complexes 1, 3, and
2
1
1
(
3
8
2
34.0 (d, J = 8.0 Hz, o-Ph), 133.1 (d, J = 41.5 Hz, i-Ph), 131.0
CP CP
4
3
2
d, J = 2.4 Hz, p-Ph), 128.5 (d, J = 9.4 Hz, m-Ph), 96.3 (d, J
.1 Hz, o-BzOEt), 91.0 (s, p-BzOEt), 86.1 (d, J = 7.4 Hz, i-BzOEt),
=
CP
CP
CP
2
CP
2
1
4.3 (d, J = 2.8 Hz, m-BzOEt), 62.8 (s, OCH CH ), 36.1 (d, J =
CP
CP
2
3
2
3
5(PDF)
1.9 Hz), 30.4 (d, J = 2.2 Hz, PCHCH ), 28.6 (d, J = 13.9 Hz,
CP
2
CP
PCHCH CH ), 27.9 (s, PCHCH CH CH ), 14.7 (s, OCH CH ).
2
2
2
2
2
2
3
Accession Codes
3
1
1
P{ H} NMR (202 MHz, CD Cl ): δ (ppm) = 27.7 (s). Selected IR
2
2
−
1
CCDC 1578509−1578514 contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge via www.ccdc.cam.ac.uk/data_request/cif, or by email-
ing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
bands (ATR): wavenumber (cm ) = 294 (νRu−Cl), 1098 (νO−C−C),
263 (ν ), 1729 (ν ).
1
C−C(O)−O
CO
4
[
Ru (μ-Cl) ((η -3,5-cycloheptadienyl)diphenylphosphine-
2
2 3
κP) ][Cl] (5). Complex 3 (240 mg, 0.400 mmol) was dissolved in
DCM (8 mL), and exposed to light (mercury lamp Heraeus TQ150
W) for 1 h under stirring. Solvent was evaporated. The residue was
washed with diethyl ether and dried to give 5 as a brick red powder
(
5
150 mg, 83%). Elemental Analysis: calcd for C H Cl P Ru : C,
38 38 4 2 2
AUTHOR INFORMATION
Corresponding Authors
*E-mail: raluca.malacea@u-bourgogne.fr. Tel.: +33 (0)3 80 39
90 38.
*E-mail: pierre.le-gendre@u-bourgogne.fr. Tel.: +33 (0)3 80 39
60 82.
■
0.68; H, 4.25. Found: C, 50.36; H, 4.33. HR-MS (ESI-pos) calcd for
+
+
[
C H Cl P Ru ] [M − Cl] : 864.96014. Found: 864.95562. (−3.4
38
38
3
2
2
1
ppm). H NMR (500 MHz, CDCl , 253 K): δ (ppm) = 7.59−7.49 (m,
8
3
H + 4H, o/m-Ph, p-Ph), 7.35−7.29 (m, 8H, o/m-Ph), 5.61−5.55 (m,
H, CH CHCH), 4.88−4.81 (m, 4H, CH CHCH), 2.99−2.94
4
2
2
3
(
m, 2H, PCH), 1.97−1.88 (m, 4H, PCHCH H ), 0.90 (dd, J = 46.3
a
b
CP
2 13 1
HH
Hz, J = 14.3 Hz, 4H, PCHCH H ). C{ H} NMR (126 MHz,
a
b
ORCID
CDCl , 253 K): δ (ppm) = 134.0 (d, J = 8.5 Hz, o/mPh), 132.1 (d,
3
CP
4
1
Miguel Ponce-Vargas: 0000-0002-6028-3167
Paul Fleurat-Lessard: 0000-0003-3114-2522
Pierre Le Gendre: 0000-0003-2635-5216
JCP = 2.4 Hz, p-Ph), 128.9 (d, JCP = 10.3 Hz, o-/m-Ph), 128.0 (d, J
CP
=
48.3 Hz, i-Ph), 87.6 (s, CH CHCH), 77.6 (s, overlapping with
=
3 2 CP CP
2
1
2
CDCl , CH CHCH), 51.8 (d, J = 36.0 Hz, PCH), 27.6 (d, J
31
1
6
(
.8 Hz, PCHCH ). P{ H} NMR (202 MHz, CD Cl , 253 K): δ
2
2
2
Notes
ppm) = 100.0 (bs).
6
The authors declare no competing financial interest.
RuCl (η -toluene)(cycloheptyldiphenylphosphine-κP) (6). In
2
a NMR tube, 20 mg (0.033 mmol) of complex 4 was dissolved in
toluene and irradiated for 3 h at room temperature with 150 W
ACKNOWLEDGMENTS
■
mercury lamp to give after complete conversion to complex 6 which
This work is supported by the CNRS, Universite
́
de Bourgogne,
ional de Bourgogne through the plan d’actions
ional pour l’innovation (PARI) and the fonds europeen de
1
was further isolated as red crystals. H NMR (500 MHz, CDCl ): δ
3
Conseil Reg
́
(
ppm) = 7.94−7.86 (m, 4H, Ph), 7.51−7.43 (m, 6H, Ph), 5.08−5.03
3
reg
dev
́
́
(
m, 2H, CH Tol), 4.95 (bd, J = 5.8 Hz, 2H, CH Tol), 4.40 (bt,
HH
3
́
eloppement regional (FEDER) programs.
JHH = 5.2 Hz, 1H, CH Tol), 3.34−3.26 (m, 1H, PCH), 2.26−2.15 (m,
2
H, cycloheptyl), 2.13 (s, 3H, CH -Tol), 1.57−1.37 (m, 6H,
3
REFERENCES
cycloheptyl), 1.36−1.26 (m, 2H, cycloheptyl), 1.04−0.94 (m, 2H,
■
13
1
cycloheptyl). C{ H} NMR (126 MHz, CDCl ): δ (ppm) = 133.8 (d,
(1) For reviews see (a) Rigby, J. H.; Kondratenko, M. A. Arene
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3
1
JCP = 39.6 Hz, C i-Ph), 133.5 (d, J = 8.0 Hz, CH Ph), 130.33 (d,
q
CP
JCP = 1.9 Hz, CH Ph), 128.2 (d, JCP = 9.9 Hz, CH Ph), 107.3 (d, JCP
=
̈
Organic Synthesis and Catalysis; Kundig, E. P., Ed.; Springer: Berlin,
4
8
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31
1
CH −cycloheptyl), 18.6 (s, CH -Tol). P{ H} NMR (202 MHz,
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(
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of the appropriate solvent were introduced in a Schlenk tube in the
H
DOI: 10.1021/acs.organomet.7b00851
Organometallics XXXX, XXX, XXX−XXX

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I
DOI: 10.1021/acs.organomet.7b00851
Organometallics XXXX, XXX, XXX−XXX