Atom transfer radical addition reactions of CCl4, CHCI 3, and P-tosyl chloride catalyzed by Cp′Ru(PPh 3)(PR3)Cl complexes

Article abstract of DOI:10.1021/om900075h

A series of Cp'Ru(PR₃)(PPh₃)Cl complexes, where Cp′ = Cp^*, Dp, Ind, Cp, Tp and PR₃ = PTA, PMe₃, PPh₃, have been used to catalyze the atom transfer radical addition (ATRA) of various chloro substrates (CC1₄, CHC1 ₃, and TsCl) to styrene and/or hexene. The complexes Cp ^*Ru(PTA)(PPh₃)Cl, Cp^*Ru(PMe ₃)(PPh₃)Cl, DpRu(PMe₃)(PPh₃)Cl, and TpRu(PMe₃)(PPh₃)Cl have been synthesized by ligand exchange reactions with Cp′Ru(PPh₃)₂Cl and characterized by NMR spectroscopy and X-ray crystallography. An alternative synthesis for CpRu(PMe₃)(PPh₃)Cl and the solid-state structure of the previously reported complex IndRu(PMe₃)(PPh ₃)Cl are also described. Among the ruthenium(II) complexes studied, Cp^*Ru(PTA)(PPh₃)Cl and Cp ^*Ru(PMe₃)(PPh₃)Cl were very active at 60 °C with TOF values of 1060 and 933 h^-1, respectively; Cp ^*Ru(PPh₃)₂Cl was the most active for the addition of CCI₄ to styrene with a TOF > 960 h^-1 at room temperature. Total turnovers (TTO) in excess of 80000 for the addition of CC1₄ to hexene were obtained for the Cp^* complexes, making these complexes the most active and robust catalysts for ATRA reported to date.

Full text of DOI:10.1021/om900075h

Organometallics 2009, 28, 4681–4688 4681
DOI: 10.1021/om900075h
Atom Transfer Radical Addition Reactions of CCl4, CHCl3, and p-Tosyl
Chloride Catalyzed by Cp0Ru(PPh3)(PR3)Cl Complexes
Radhika P. Nair, Tae Ho Kim, and Brian J. Frost*
Department of Chemistry, University of Nevada, Reno, Nevada 89557-0216
Received January 30, 2009
A series of Cp0Ru(PR3)(PPh3)Cl complexes, where Cp0 = Cp*, Dp, Ind, Cp, Tp and PR3 = PTA,
PMe3, PPh3, have been used to catalyze the atom transfer radical addition (ATRA) of various chloro
substrates (CCl4, CHCl3, and TsCl) to styrene and/or hexene. The complexes Cp*Ru(PTA)(PPh3)Cl,
Cp*Ru(PMe3)(PPh3)Cl, DpRu(PMe3)(PPh3)Cl, and TpRu(PMe3)(PPh3)Cl have been synthesized
by ligand exchange reactions with Cp0Ru(PPh3)2Cl and characterized by NMR spectroscopy and
X-ray crystallography. An alternative synthesis for CpRu(PMe3)(PPh3)Cl and the solid-state
structure of the previously reported complex IndRu(PMe3)(PPh3)Cl are also described. Among
the ruthenium(II) complexes studied, Cp*Ru(PTA)(PPh3)Cl and Cp*Ru(PMe3)(PPh3)Cl were very
active at 60 °C with TOF values of 1060 and 933 h-1, respectively; Cp*Ru(PPh3)2Cl was the most
active for the addition of CCl4 to styrene with a TOF >960 h-1 at room temperature. Total turnovers
(TTO) in excess of 80 000 for the addition of CCl4 to hexene were obtained for the Cp* complexes,
making these complexes the most active and robust catalysts for ATRA reported to date.
Introduction
yields and stereoselectivity.2,6,8 A wide variety of metal com-
plexes catalyze ATRA, including those of copper,9-11 iron,10,12
nickel,6,13 and palladium.14 Ruthenium complexes, in particular,
have played a significant role, with RuCl2(PPh3)3 being a highly
efficient and versatile catalyst for ATRA.15-28 The diverse set of
The addition of halogenated compounds to olefins was first
reported in the late 1930s and is commonly referred to as
Kharasch addition or atom transfer radical addition
(ATRA).1 It is an effective method for C-C bond formation,
and its applications in synthetic organic chemistry have been well
reviewed.2-7 Transition-metal-catalyzed ATRA has gained
considerable interest since the early 1970s, as it provides higher
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*To whom correspondence should be addressed. Tel:+1-775-784-
1993. Fax: +1-775-784-6804. E-mail: Frost@unr.edu.
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1945, 102, 128–128. (c) Kharasch, M. S.; Elwood, E. V.; Urry, W. H. J. Am.
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r
2009 American Chemical Society
Published on Web 07/20/2009
pubs.acs.org/Organometallics

4682 Organometallics, Vol. 28, No. 16, 2009
Nair et al.
Scheme 1
Scheme 2
ruthenium catalysts for ATRA includes bimetallic ruthenium
complexes,18 cationic systems supported by phosphines19 or
chelating P,N ligands,20 η5-carborane complexes,21 carbene-
containing compounds,22,23 and resin-supported catalysts.24
Recent developments in ATRA chemistry have focused on
half-sandwich Ru(II) and Ru(III) phosphine complexes bearing
η6-arene or η5-cyclopentadienyl type ligands.16-20,22,24-28
A general mechanism for transition-metal-catalyzed
ATRA is represented in Scheme 1.29,30 A detailed mechanism
of the RuCl2(PPh3)3-catalyzed ATRA has been described by
Davis and co-workers.29 Initiation presumably involves the
dissociation of a phosphine ligand, generating a coordina-
tively unsaturated RuII complex, which in turn activates the
carbon-halogen bond, yielding a RuIII-X species and
carbon-centered radical. The latter adds to the olefin, gen-
erating a new carbon radical. Transfer of a halogen atom
from the metal halide to the carbon radical yields the 1:1
Kharasch product and regenerates the RuII catalyst. In the
presence of a large excess of olefin, atom transfer radical
polymerization (ATRP) can occur, as observed by Sawamo-
to31 and Matyjaszewski.32 ATRA and ATRP are mechan-
istically similar, and several metal complexes are known to
catalyze both reactions.11a,33
Azobis(isobutyronitrile) (AIBN) has recently been em-
ployed in Ru-catalyzed ATRA reactions by Severin and
co-workers, who have suggested that AIBN allows for the
reduction of Cp*RuIII(PPh3)Cl2 back to the catalytically
active Cp*RuII(PPh3)Cl.17 Recently, this methodology has
been applied with great success to copper-catalyzed ATRA
reactions.11b,11c Our group has described the synthesis,
characterization, and activity toward transfer hydrogena-
tion of a series of Cp0Ru(PTA)(PR3)X complexes, where
Cp0 = η5-C5Me-5 (Cp*), η5-C8H-9 (Dp), η5-C9H-7 (Ind),
η5-C5H-5 (Cp), PR3=1,3,5-triaza-7-phosphadamantane (PTA),
PPh3, and X = Cl, H.34 As part of our continued interest in
ruthenium phosphine chemistry,34,35 we report here the effi-
ciency of series of Cp0Ru(PR3)(PPh3)Cl (PR3 = PTA, PMe3,
PPh3) complexes as catalysts for the addition of CCl4, CHCl3,
and p-tosyl chloride (TsCl) to styrene and hexene in the presence
of AIBN (Scheme 2).
Experimental Section
General Methods. All reactions were performed under a dry
nitrogen atmosphere, using conventional Schlenk vacuum-line
techniques. Reagents were purchased from commercial suppli-
ers and used as received. Solvents were dried with molecular
sieves and degassed with N2, prior to use. Cp*Ru(PPh3)2Cl,36
DpRu(PPh3)2Cl,37 IndRu(PPh3)2Cl,38 CpRu(PPh3)2Cl,39 Tp-
Ru(PPh3)2Cl,40 CpRu(PTA)(PPh3)Cl,34,41 DpRu(PTA)(PPh3)-
Cl,34 TpRu(PTA)(PPh3)Cl,42 IndRu(PTA)(PPh3)Cl,34 Ind-
Ru(PMe3)(PPh3)Cl,43 and 1,3,5-triaza-7-phosphaadamantane
(PTA)44 were prepared as described in the literature. Kharasch
reactions were carried out in standard NMR tubes or in 1.5 mL
vials. The 1:1 Kharasch adduct was characterized by 1H NMR
spectroscopy. Each catalytic run was repeated at least twice to
ensure reproducibility. NMR spectra were recorded with a
Varian NMR System 400 spectrometer. 1H NMR spectra were
referenced to a residual solvent relative to tetramethylsilane
(TMS). Phosphorus chemical shifts are relative to an external
reference of 85% H3PO4 in D2O, with positive values downfield
of the reference. Elemental analyses were performed by Midwest
Microlab, LLC. X-ray crystallographic data were collected at
100((1) K on a Bruker APEX CCD diffractometer with Mo KR
˚
radiation (λ = 0.710 73 A) and a detector-to-crystal distance of
4.94 cm. Data collection was optimized utilizing the APEX2
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Article
Organometallics, Vol. 28, No. 16, 2009 4683
Table 1. Crystallographic Data and Structural Refinement Details for Cp*Ru(PTA)(PPh3)Cl, Cp*Ru(PMe3)(PPh3)Cl, IndRu(PMe3)-
(PPh3)Cl, and TpRu(PMe3)(PPh3)Cl
Cp*Ru(PTA)(PPh3)Cl (1) Cp*RuCl(PMe3)(PPh3) (6) IndRuCl(PMe3)(PPh3) (8) TpRuCl(PMe3)(PPh3) (10)
empirical formula
formula wt
color
C
691.17
orange
100(2)
0.710 73
monoclinic
P21/n
11.6045(2)
14.8894(3)
18.4456(4)
90
102.0290(10)
90
3117.12(11)
4
1.473
34H42ClN3P2Ru
C31H39ClP2Ru
610.08
orange
100(2)
0.710 73
monoclinic
P21/n
11.3789(2)
14.3410(2)
18.3738(2)
90
107.3420(10)
90
2862.03(7)
4
1.416
C30H31ClP2Ru
590.01
red
100(2)
0.710 73
C30H34N6BClP2Ru
687.90
green
100(2)
0.710 73
monoclinic
P21/n
12.3342(2)
20.1362(3)
13.1231(2)
90
105.6100(10)
90
3139.09(8)
4
1.456
T (K)
wavelength (A)
˚
cryst syst
space group
triclinic
P1
˚
a (A)
12.3176(2)
13.1046(2)
17.1601(3)
80.5320(10)
82.1640(10)
89.4570(10)
2706.45(8)
4
1.448
0.813
1208
0.16 ꢀ 0.12 ꢀ 0.10
1.58-27.64
-15 e h e 16
-17 e k e 15
-22 e l e 22
51 558
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z
Dcalcd (Mg/m3)
abs coeff (mm-1
F(000)
)
0.720
1432
0.771
1264
0.717
1408
cryst size (mm3)
2θ range (deg)
index ranges
0.27 ꢀ 0.13 ꢀ 0.04
1.77-27.50
-12 e h e 15
-19 e k e 15
-23 e l e 13
34 336
0.16 ꢀ 0.07 ꢀ 0.06
1.83-28.28
-15 e h e 15
-19 e k e 19
-19 e l e 24
31 805
0.19 ꢀ 0.07 ꢀ 0.02
1.90-26.00
-15 e h e 12
-24 e k e 24
-14 e l e 16
27 640
no. of rflns collected
no. of indep rflns
Rint
7153
0.0507
6867
0.0432
12 486
0.0390
5785
0.0662
no. of data/restraints/params 7153/0/360
GOF on F2
6867/0/324
1.094
12 486/0/619
1.087
5785/0/373
1.038
1.026
final R indices (I > 2σ(I))
R1 = 0.0364
wR2 = 0.0749
R1 = 0.0518
wR2 = 0.0797
699360
R1 = 0.0301
wR2 = 0.0631
R1 = 0.0434
wR2 = 0.0808
713868
R1 = 0.0289
wR2 = 0.0675
R1 = 0.0448
wR2 = 0.0827
713866
R1 = 0.0420
wR2 = 0.0781
R1 = 0.0704
wR2 = 0.0844
713867
R indices (all data)
CCDC no.
software with a 0.5° rotation about ω between frames and an
exposure time of 10 s per frame. Data integration, correction for
Lorentz and polarization effects, and final cell refinement were
performed using SAINTPLUS and corrected for absorption
using SADABS. The structures were solved using direct meth-
ods followed by successive least-squares refinement on F2 using
the SHELXTL 6.10 software package.45 All non-hydrogen
atoms were refined anisotropically, and hydrogen atoms were
placed in calculated positions. Crystallographic data and data
collection parameters are given in Table 1. A complete list of
bond lengths and angles may be found in the Supporting
Information.
under vacuum, and the solid was washed with methanol (3 ꢀ
10 mL), affording 220 mg of 6 as a yellow powder (57% yield).
1H NMR (400 MHz, CD2Cl2): δ 7.61-7.28 (m, 15H, Ph); 1.28
2
(s, 15H, Cp(CH3)5); 1.06 (d, 9H, P(CH3)3, JPH = 8.4 Hz).
31P{1H} NMR (162 MHz, CD2Cl2): δ 47.5 (d, PPh3, 2JPP = 44.1
Hz); 1.1 (d, PMe3, JPP = 44.1 Hz). Anal. Calcd for
2
C31H39P2RuCl: C, 61.03; H, 6.44; N, 0.00. Found: C, 60.96;
H, 6.49; N, 0.04. Orange crystals suitable for X-ray diffraction
were obtained by slow cooling of a solution of 6 in hot methanol.
Synthesis of DpRu(PMe3)(PPh3)Cl (7). A solution of DpRu-
(PPh3)2Cl (0.600 g, 0.78 mmol) and PMe3 (200 μL, 1.93 mmol) in
toluene (50 mL) was heated in an oil bath at 35 °C for 2 h under
nitrogen. The solvent was evaporated under vacuum, and the
resulting solid was dissolved in CH2Cl2 and purified by column
chromatography on silica. The band eluted with dichloro-
methane was collected and dried under vacuum, yielding
270 mg of 7 as an orange crystalline solid (60% yield). 1H
NMR (400 MHz, CD2Cl2): δ 7.56-7.32 (m, 15H, Ph); 4.03, 3.63,
3.15 (s, 3H, Cp), 2.50-2.10 (m, 6H, Cp(CH2)3); 1.17 (d, 9H,
P(CH3)3, 2JPH = 8.8 Hz). 31P{1H} NMR (162 MHz, CD2Cl2): δ
49.1 (d, PPh3, 2JPP = 46.8 Hz); 0.5 (d, PMe3, 2JPP = 46.8 Hz).
Anal. Calcd for C29H33P2RuCl: C, 60.05; H, 5.73; N,
0.00. Found: C, 60.08; H, 5.69; N, 0.06.
Synthesis of CpRu(PMe3)(PPh3)Cl (9). CpRu(PMe3)-
(PPh3)Cl was synthesized by an alternative method from that
reported.46 A mixture of CpRu(PPh3)2Cl (1.0 g, 1.38 mmol) and
PMe3 (300 μL, 2.90 mmol) in 80 mL of toluene was heated in an
oil bath at 35 °C for 30 h under nitrogen. The reaction mixture
was dried under vacuum. The resulting solid residue was dis-
solved in CH2Cl2 and purified by column chromatography on
silica. The fraction eluted with dichloromethane was collected
and dried under vacuum, affording 9 as a yellow crystalline solid
Synthesis of Cp*Ru(PTA)(PPh3)Cl (1). Cp*Ru(PPh3)2Cl
(0.300 g, 0.37 mmol) and PTA (0.0588 g, 0.37 mmol) were
dissolved in 70 mL of CH2Cl2 and refluxed under nitrogen for
2 h. The solution was cooled to room temperature, filtered, and
pulled dry under vacuum. The resulting solid was washed with
water followed by diethyl ether (3 ꢀ 10 mL), affording 169 mg of
1 as an orange powder (65% yield). 1H NMR (400 MHz,
CDCl3): δ 7.62-7.33 (m, 15H, Ph); 4.39, 4.27 (AB quartet,
2JH H = 13 Hz, 6H, NCH2N); 3.95, 3.36 (AB quartet, 2JH H
=
A
B
A
B
15 Hz, 6H, PCH2N); 1.34 (s, 15H, CH3). 31P{1H} NMR (162
MHz, CDCl3): δ 47.6 (d, PPh3, 2JPP = 40.4 Hz); -38.9 (d, PTA,
2JPP = 40.4 Hz). Anal. Calcd for C34H42N3P2RuCl: C, 59.08; H,
6.12; N, 6.08. Found: C, 59.28; H, 6.17; N, 5.94. Orange crystals
suitable for X-ray diffraction were obtained by slow diffusion of
diethyl ether into a toluene solution of 1.
Synthesis of Cp*Ru(PMe3)(PPh3)Cl (6). Cp*Ru(PPh3)2Cl
(0.500 g, 0.63 mmol) and excess PMe3 (200 μL, 1.93 mmol) were
dissolved in 30 mL of toluene and heated in an oil bath at 35 °C
for 10 min under nitrogen. The toluene was then evaporated
(45) (a) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112–122. (b)
Sheldrick, G. M. SHELXTL: Structure Determination Software Suite,
Version 6.10; Bruker AXS: Madison, WI, 2001.
(46) Bruce, M. I.; Wong, F. S.; Skelton, B. W.; White, A. H. J. Chem.
Soc., Dalton Trans. 1981, 1398–1405.

4684 Organometallics, Vol. 28, No. 16, 2009
Nair et al.
(370 mg, 50% yield). 1H NMR data for CpRu(PMe3)(PPh3)Cl
obtained by this method are identical with those reported in the
literature.46 31P{1H} NMR (162 MHz, CD2Cl2): δ 48.6 (d, PPh3,
2JPP = 38.2 Hz); 2.1 (d, PMe3, 2JPP = 38.2 Hz).
Synthesis of TpRu(PMe3)(PPh3)Cl (10). A mixture of TpRu-
(PPh3)2Cl (1.150 g, 1.31 mmol) and PMe3 (300 μL, 2.90 mmol) in
80 mL of toluene was heated in an oil bath at 35 °C for 4 h under
nitrogen. The solvent was evaporated under vacuum, and the
residue was dissolved in CH2Cl2 and purified by column chro-
matography on silica. The band eluted with dichloromethane
was collected and dried under vacuum, yielding 400 mg of 10 as a
yellow-green crystalline solid (45% yield). 1H NMR (400 MHz,
CD2Cl2): δ 7.98 (1H, pyrazolyl); 7.65-7.21 (m, 18H, PPh3 and
pyrazolyl); 6.60 (1H, pyrazolyl); 6.18 (1H, pyrazolyl); 5.78 (1H,
pyrazolyl); 5.70 (1H, pyrazolyl); 5.57 (1H, pyrazolyl); 1.10 (d,
2
9H, P(CH3)3, JPH = 8.0 Hz). 31P{1H} NMR (162 MHz,
2
CD2Cl2): δ 50.4 (d, PPh3, JPP = 35.1 Hz); 10.4 (d, PMe3,
2JPP = 35.1 Hz). Anal. Calcd for C31H39P2RuCl: C, 52.38; H,
4.98; N, 12.22. Found: C, 52.47; H, 4.89; N, 12.00. Green
crystals suitable for X-ray diffraction were obtained by slow
evaporation of a dichloromethane solution of 10.
Catalytic Experiments.47 ATRA of CCl4 to Styrene/Hexene.
In a 1.5 mL vial 1 mol % of catalyst (0.0138 mmol), 5 mol % of
AIBN (11.3 mg, 0.069 mmol), styrene (158 μL, 1.38 mmol) or
hexene (171 μL, 1.38 mmol), CCl4 (533 μL, 5.52 mmol), and
hexamethylbenzene as an internal standard (5 mg, 0.031 mmol)
were added. Toluene-d8 was added to bring the total volume to
1 mL. The resulting solution was sealed in an NMR tube and
heated at 60 °C in an oil bath. The formation of product was
monitored by 1H NMR spectroscopy at predetermined intervals.
ATRA of p-TsCl to Styrene. In a 1.5 mL vial 1 mol % of
catalyst (0.0044 mmol), 5 mol % of AIBN (4 mg, 0.022 mmol),
styrene (50 μL, 0.44 mmol), p-TsCl (99 mg, 0.52 mmol), and
hexamethylbenzene as an internal standard (5 mg, 0.031 mmol)
were added. Toluene-d8 was added to bring the total volume to
1 mL. The resulting solution was sealed in an NMR tube
and heated at 60 °C in an oil bath. The formation of product
was monitored by 1H NMR spectroscopy at predetermined
intervals.
Figure 1. Cp0Ru(PR3)(PPh3)Cl complexes used as catalyst pre-
cursors for atom transfer radical addition.
Table 2. 31P{1H} Chemical Shift (ppm) and Coupling Constants
(Hz) for the Series of Cp0Ru(PR3)(PPh3)Cl Complexes (Cp0 =
Cp*, Dp, Cp, Ind, Tp; PR3 = PTA, PMe3) in CD2Cl2
complex
31P{1H} NMR
2JPP, Hz
Cp*Ru(PTA)(PPh3)Cla (1)
47.6 (PPh3)
-38.9 (PTA)
43.2 (PPh3)
-39.6 (PTA)
50.8 (PPh3)
-22.6 (PTA)
48.4 (PPh3)
-34.5 (PTA)
46.9 (PPh3)
-34.2 (PTA)
47.5 (PPh3)
1.1 (PMe3)
49.1 (PPh3)
0.5 (PMe3)
50.1 (PPh3)
16.3 (PMe3)
48.6 (PPh3)
2.1 (PMe3)
50.4 (PPh3)
10.4 (PMe3)
40.4
DpRu(PTA)(PPh3)Cl (2)34
IndRu(PTA)(PPh3)Cl (3)34
CpRu(PTA)(PPh3)Cl (4)34,41
TpRu(PTA)(PPh3)Cla (5)42
Cp*Ru(PMe3)(PPh3)Cl (6)
DpRu(PMe3)(PPh3)Cl (7)
IndRu(PMe3)(PPh3)Cla (8)43
CpRu(PMe3)(PPh3)Cl (9)
TpRu(PMe3)(PPh3)Cl (10)
45.2
42.8
45.0
33.1
44.1
46.8
44.8
38.2
35.1
ATRA of CHCl3 to Styrene. In a 1.5 mL vial 1 mol % of
catalyst (0.0138 mmol), 5 mol % of AIBN (11.3 g, 0.069 mmol),
styrene (158 μL, 1.38 mmol), and hexamethylbenzene as an
internal standard (5 mg, 0.031 mmol) were added. The reaction
mixture was brought to a total volume of 1 mL with the addition
of CHCl3 and heated at 60 °C in an oil bath. Aliquots of the
reaction mixture (∼30 μL) were diluted with CDCl3 and ana-
lyzed by 1H NMR spectroscopy.
Results and Discussion
a In CDCl3.
The series of Cp0Ru(PR3)(PPh3)Cl complexes 1-10
(Figure 1) have been synthesized in good yields by ligand
exchange of the Cp0Ru(PPh3)2Cl complexes 11-15 with the
appropriate PR3 ligand (PTA or PMe3). The synthesis and
characterization of CpRu(PTA)(PPh3)Cl,41 DpRu(PTA)-
(PPh3)Cl,34 IndRu(PTA)(PPh3)Cl,34 TpRu(PTA)(PPh3)-
Cl,42 CpRu(PMe3)(PPh3)Cl,46 IndRu(PMe3)(PPh3)Cl,43
Cp*Ru(PPh3)2Cl,36 DpRu(PPh3)2Cl,37 IndRu(PPh3)2Cl,38
CpRu(PPh3)2Cl,39 and TpRu(PPh3)2Cl40 have been pre-
viously reported in the literature. We report here the new
compounds Cp*Ru(PTA)(PPh3)Cl, Cp*Ru(PMe3)(PPh3)-
Cl, DpRu(PMe3)(PPh3)Cl, and TpRu(PMe3)(PPh3)Cl,
along with the solid-state structure of IndRu(PMe3)(PPh3)Cl
and an alternative synthesis for CpRu(PMe3)(PPh3)Cl. We
have obtained Cp*Ru(PTA)(PPh3)Cl (1) in modest yield
(65%) by refluxing equimolar amounts of PTA and Cp*Ru-
(PPh3)2Cl in toluene. Complexes 6, 7, 9, and 10 were pre-
pared by heating (35 °C) Cp0Ru(PPh3)2Cl with excess PMe3
in toluene.
The compounds 1, 6, 7, and 10 were characterized by
elemental analysis and NMR spectroscopic techniques (1H
and 31P{1H} NMR). In addition, the structures of 1, 6, 8, and
10 were further confirmed by X-ray crystallography (vide
31
infra). The P{1H} NMR spectra of the series of Cp0Ru-
(PR3)(PPh3)Cl complexes each consist of two doublets due
=
2
to coupling of the inequivalent phosphorus nuclei: Jpp
40.4 Hz (1), 44.1 Hz (6), 46.8 Hz (7), 38.2 Hz (9), 35.1 Hz (10)
(Table 2). The PTA and PMe3 ligands are more sensitive
to the metal environment than PPh3, as evidenced by the
range of 31P chemical shifts for PTA (Δppm ≈ 16; -22.6 to
-38.9 ppm) and PMe3 (Δppm ≈ 16; 0.5-16.3 ppm) versus
PPh3 (Δppm ≈ 7.5; 43.2-50.8 ppm).
(47) For ease of comparison we have, in general, followed the
experimental procedure from ref 17 for all catalytic reactions.

Article
Organometallics, Vol. 28, No. 16, 2009 4685
Figure 2. Thermal ellipsoid (50% probability) representation
of Cp*Ru(PTA)(PPh3)Cl (1) with the atomic numbering
scheme. Hydrogen atoms have been omitted for clarity. Selected
˚
bond lengths (A) and angles (deg): Ru1-Cl1=2.4494(6); Ru1-
Figure 4. Thermal ellipsoid (50% probability) representation
of IndRu(PMe3)(PPh3)Cl (8) with the atomic numbering
scheme. Hydrogen atoms have been omitted for clarity. Selected
P1=2.3008(7); Ru1-P2=2.2853(7); Ru1-Cp*cent=1.868; P1-
Ru1-P2=94.81(2); P1-Ru1-Cl1=84.22(2); P2-Ru1-Cl1 =
92.14(2).
˚
bond lengths (A) and angles (deg): Ru1-Cl1=2.4399(6); Ru1-
P1=2.2608(7); Ru1-P2=2.3077(6); Ru1-Cp*cent=1.895; P1-
Ru1-P2=98.72(2); P1-Ru1-Cl1=87.03(2); P2-Ru1-Cl1=
92.54(2).
Figure 3. Thermal ellipsoid (50% probability) representation
of Cp*Ru(PMe3)(PPh3)Cl (6) with the atomic numbering
scheme. Hydrogen atoms have been omitted for clarity. Selected
˚
bond lengths (A) and angles (deg): Ru1-Cl1 = 2.4583(6);
Ru1-P1 = 2.3006(7); Ru1-P2 = 2.3049(7); Ru1-Cp*cent
=
1.870; P1-Ru1-P2 = 96.78(2); P1-Ru1-Cl1 = 83.82(2); P2-
Ru1-Cl1 = 92.75(2).
Figure 5. Thermal ellipsoid (50% probability) representation
of TpRu(PMe3)(PPh3)Cl (10) with the atomic numbering
scheme. Hydrogen atoms have been omitted for clarity. Selected
Structures of Cp0Ru(PPh3)(PR3)Cl Complexes (Cp0=Cp*,
Ind, Tp; PR3=PTA, PMe3). Orange plates of Cp*Ru(PTA)-
(PPh3)Cl (1) suitable for X-ray diffraction were obtained
by slow diffusion of diethyl ether into a toluene solution of
1. A thermal ellipsoid representation of 1 is depicted in
Figure 2. Complex 1 exhibits a classic piano-stool geome-
try with one PTA, PPh3, a chloride, and a η5-Cp* ring
occupying the six coordination sites around the ruthenium
˚
bond lengths (A) and angles (deg): Ru1-Cl1=2.4046(8); Ru1-
P1 = 2.2993(11); Ru1-P2 = 2.3125(9); Ru1-N1 = 2.097(3);
Ru1-N3 = 2.162(3); Ru1-N5 = 2.132(3); P1-Ru1-P2 =
96.31(3); P1-Ru1-Cl1=94.98(3); P2-Ru1-Cl1=90.66(3).
slightly smaller than that reported for the Dp and Ind
analogues.34
Thermal ellipsoid representations of the solid-state struc-
tures of Cp*Ru(PMe3)(PPh3)Cl (6), IndRu(PMe3)(PPh3)Cl
(8), and TpRu(PMe3)(PPh3)Cl (10), along with the atomic
numbering schemes, are depicted in Figures 3-5, respectively.
˚
atom. The Ru-Cl (2.4494(6) A) and Ru-P (2.3008(7),
2.2853(7) A) bond distances are comparable to the Cp,
˚
Dp, and Ind analogues.34 The P-Ru-P bond angle,
94.81(2)°, is similar to that of the Cp analogue and is

4686 Organometallics, Vol. 28, No. 16, 2009
Nair et al.
0
0
˚
Table 3. Selected Bond Lengths (A) and Angles (deg) for a Series of Cp Ru(PPh3)(PR3)Cl Complexes (Cp = Cp*, Ind, Tp and PR3 =
PTA, PMe3)a
Cp*Ru(PTA)(PPh3)Cl (1)
Cp*Ru(PMe3)(PPh3)Cl (6)
IndRu(PMe3)(PPh3)Cl (8)
TpRu(PMe3)(PPh3)Cl (10)
Ru-Cl
2.4494(6)
2.3008(7)
2.2853(7)
1.868
94.81(2)
84.22(2)
92.14(2)
51.9
2.4583(6)
2.3006(7)
2.3049(7)
1.870
96.78(2)
83.82(2)
92.75(2)
62.7
2.4399(6)
2.2608(7)
2.3077(6)
1.895
98.72(2)
87.03(2)
92.54(2)
51.6
2.4046(8)
2.2993(11)
2.3125(9)
Ru-P1
Ru-P2 0
Ru-Cp cent
P1-Ru-P2
P1-Ru-Cl
P2-Ru-Cl
Cp-ML2
96.31(3)
94.98(3)
90.66(3)
a See the Supporting Information for further details.
Table 4. Atom Transfer Radical Addition of CCl4 to Styrene Catalyzed by the Cp0Ru(PR3)(PPh3)Cl Complexes 1-10a
entry
cat.
substrate
TOFb (h-1
)
time (h)
yieldc (%)
1d
2
Cp*Ru(PTA)(PPh3)Cl (1)
Cp*Ru(PTA)(PPh3)Cl (1)
Cp*Ru(PTA)(PPh3)Cl (1)
Cp*Ru(PTA)(PPh3)Cl (1)
DpRu(PTA)(PPh3)Cl (2)
IndRu(PTA)(PPh3)Cl (3)
CpRu(PTA)(PPh3)Cl (4)
TpRu(PTA)(PPh3)Cl (5)
Cp*RuCl(PMe3)(PPh3) (6)
DpRuCl(PMe3)(PPh3) (7)
IndRuCl(PMe3)(PPh3) (8)
CpRuCl(PMe3)(PPh3) (9)
TpRuCl(PMe3)(PPh3) (10)
CCl4
CCl4
CCl4
CCl4
CCl4
CCl4
CCl4
CCl4
CCl4
CCl4
CCl4
CCl4
CCl4
33
4
>99
>99
>99
>99
>99
>99
61
1060
415
444
24.1
12.6
2.4
0.37
0.63
1.25
3.5
8
28
75
1.25
2
3e
4f
5
6
7
8
9
10
11
12
13
27
933
51.1
20.0
8.7
>99
>99
>99
95
6
11
31
46
aAll reactions were performed in toluene-d8 at 60 °C using 1 mol % of catalyst and 5 mol % of AIBN; the ratio of CCl4 to styrene is 4:1. b TOF is defined
as (mol of product)/((mol of cat.) h), calculated at 50-65% conversion of styrene. c The yield is determined by 1H NMR spectroscopy of product versus
internal standard. dAt 25 °C. e Without AIBN. f 10 mol % PPh3.
Table 5. Atom Transfer Radical Addition of CCl4 to Styrene
Catalyzed by Cp0Ru(PR3)2Cl Complexes 11-18 (PR3=
PPh3, PTA)a
Table 6. TTO Values Obtained at 0.005 mol % Catalyst Loading
for the Addition of CCl4 to Styrene Catalyzed by Cp0Ru(PR3)-
(PPh3)Cl Complexes (PR3 = PTA, PMe3, PPh3)a
entry
cat.
substrate TOFb (h-1) time (h) yieldc (%)
entry
cat.
TTOb
time (h)
yieldc (%)
1d
2
3
4
Cp*Ru(PPh3)2Cl (11) CCl4
DpRu(PPh3)2Cl (12) CCl4
IndRu(PPh3)2Cl (13) CCl4
CpRu(PPh3)2Cl (14) CCl4
TpRu(PPh3)2Cl (15) CCl4
Cp*Ru(PTA)2Cl (16) CCl4
DpRu(PTA)2Cl (17) CCl4
CpRu(PTA)2Cl (18) CCl4
>960
389.2
234.4
61.8
0.1
1.25
1.75
2.75
55
2.5
24
24
96
1
2
3
Cp*Ru(PTA)(PPh3)Cl (1)
Cp*Ru(PMe3)(PPh3)Cl (6)
Cp*Ru(PPh3)2Cl (11)
11 600
6 000
16 400
24
24
24
58
30
82
>99
>99
>99
38
>99
31
a All reactions were performed in toluene-d8 at 60 °C with 0.005
mol % of catalyst and 5 mol % of AIBN ; the ratio of CCl4 to styrene
is 4:1. b TTO is defined as (mol of product)/(mol of cat.). c NMR
yield determined by 1H NMR spectroscopy of product versus internal
standard.
5
6e
7e
8e
44.1
5
a All reactions were performed in toluene-d8 at 60 °C using 1 mol % of
catalyst and 5 mol % of AIBN; the ratio of CCl4 to styrene is 4:1. b TOF
is defined as (mol of product)/((mol of cat.) h), calculated at 50-65%
conversion of styrene. c The yield is determined by 1H NMR spectros-
copy of product versus internal standard. d Room temperature, TOF
calculated at 96% yield. e For solubility reasons, the reactions were
performed in CD2Cl2.
limited total turnovers (TTO). For example, Cp*RuCl-
(PPh3)2 and Cp*RuCl2(PPh3) catalyzed addition of CCl4 to
styrene with TTO values of 1600-170026 and 13 200,17
respectively. We hypothesized that replacement of one labile
PPh3 ligand with a more strongly bound ligand, such as PTA
or PMe3, would increase stability and therefore longevity of
the catalyst. Complexes 1-10 were examined as catalysts for
the addition of CCl4 to styrene (Table 4). Complex 1, with the
electron-rich Cp* ligand, exhibited the highest activity, with
>99% conversion in 22 min at 60 °C (entry 2, Table 4). A
TOF value of 1060 h-1 and TTO of 11 600 was achieved with
1; these values are comparable to the highest ones reported
for a Ru ATRA catalyst (TOF = 1500 h-1, TTO = 9000).21b
Even at room temperature catalyst 1 provided >99% con-
version in 4 h (TOF = 33 h-1; Table 4, entry 1). Trends in
catalytic activity for compounds 1-10 toward addition of
CCl4 to styrene correlate with the electron-donating ability
of the Cp0 ligand: Cp*. Dp>Ind>Cp>Tp. These results
indicate that Cp0 ligands play a significant role in the catalyst
performance. For slow reactions (>10 h), although complete
Orange crystals of 6 suitable for X-ray diffraction were
obtained by slowly cooling a hot methanol solution of 6.
X-ray-quality crystals of 8 and 10 were obtained by layering a
dichloromethane solution of 8 with acetone and slowly eva-
porating a dichloromethane solution of 10, respectively. All
three piano-stool complexes consist of a Cp0 ancillary ligand
(η5-Cp*, Ind, η3-Tp) coordinatedtorutheniumalongwithone
PPh3, PMe3, and a chloride ligand. The Ru-Cl and Ru-P
bond distances are comparable and are observed to be in the
˚
ranges 2.404-2.458 and 2.260-2.312 A, respectively
(Table 3). The P1-Ru-Cl bond angle for 10 (94.98°) is larger
than that for the Cp* and Ind analogues (83.82, 87.03°).
Catalytic Activity. Current ruthenium catalysts for ATRA,
such as Cp0Ru(PPh3)2Cl, are active but have exhibited

Article
Organometallics, Vol. 28, No. 16, 2009 4687
Figure 7. Kinetics plot for the addition of p-TsCl to styrene,
yielding the Kharasch product (() catalyzed by IndRu(PTA)-
(PPh3)Cl (8) and followed by H NMR spectroscopy. Condi-
Figure 6. Kinetics plot for the addition of CCl4 to styrene (2),
yielding the Kharasch product ((), (1,3,3,3-tetrachloropro-
pyl)benzene, catalyzed by Cp*Ru(PTA)(PPh3)Cl and followed
by 1H NMR spectroscopy. Conditions: 60 °C, 1 mol % of
catalyst, 5% of AIBN.
1
tions: 60 °C, 1 mol % of 8, 5% of AIBN.
performance relative to their mixed-phosphine counterparts.
We also tested the catalytic activity of the substitionally inert
Cp0Ru(PTA)2Cl complexes 16-18, of which only the Cp*
complex exhibited any significant reactivity (Table 5, entries
6-8). The reactivity order was Cp0Ru(PPh3)2Cl > Cp0Ru-
(PR3)(PPh3)Cl>Cp0Ru(PTA)2Cl. These results suggest that
the dissociation of the phosphine is crucial in the reaction.
Substitution of one of the two labile PPh3 ligands in Cp0Ru-
(PPh3)2Cl with a strongly bound phosphine, such as PTA or
PMe3, lead to reduced activity of the mixed-phosphine
complexes 1-10.
The Cp*Ru(PPh3)2Cl-catalyzed reaction was remarka-
bly fast; a 96% yield was obtained after only 6 min at
room temperature (TOF > 960 h-1), as compared to
99% yield after 4 h for 1 (TOF 33 h-1). Using 0.005 mol
% of 11, a TTO of 16 400 was obtained after 24 h at
60 °C (Table 6, entry 3). Reducing the catalyst loading of 1
from 1 mol % to 0.005 mol %, we obtained a TTO of 11 600
in 24 h, which is slightly lower than that reported for
Cp*Ru(PPh3)Cl217 (Table 6, entry 1). The PMe3 analogue
6, at 0.005 mol % catalyst loading, provided a TTO of
6 000 after 24 h (Table 6, entry 2).
The plot of [styrene] and Kharasch product formation
versus time for the reaction of CCl4 with styrene catalyzed by
1 (Figure 6) contains a sigmoidal curve, suggesting an
initiation step. Similar plots for the addition of CCl4 to
styrene with a variety of Cp0Ru(PR3)(PPh3)Cl complexes
are available in the Supporting Information, and all show
various degrees of induction. The induction is presumably
due to a combination of phosphine dissociation and activa-
tion of the C-Cl bond. It is likely that C-Cl bond activation
is the more important component, as the p-TsCl reactions
(vide infra) show no induction period.49,50 The potential
importance of phosphine dissociation was examined by
addition of excess PPh3 (10 mol %) to the catalytic mixture.
As expected, PPh3 inhibits the reaction rate, although the
reaction still proceeds to >99% conversion (Table 4, entry 4).
This is in contrast to the case for other catalysts, where the
Table 7. Atom Transfer Radical Addition of p-TsCl to Styrene
Catalyzed by Complexes 1-10a
TOFb time yieldc
entry
cat.
substrate
(h-1
)
(h)
(%)
1
2
3
4
5
6
7
8
Cp*Ru(PTA)(PPh3)Cl (1) TsCl
DpRu(PTA)(PPh3)Cl (2) TsCl
IndRu(PTA)(PPh3)Cl (3) TsCl
45.5
23.6
53.4
20.6
1.2
3.8
96
5.8
4.8
7
52
5
12
29
6
75
2.5
95
90
95
66
97
96
33
99
40
96
CpRu(PTA)(PPh3)Cl (4)
TpRu(PTA)(PPh3)Cl (5)
TsCl
TsCl
Cp*RuCl(PMe3)(PPh3) (6) TsCl
DpRuCl(PMe3)(PPh3) (7) TsCl
IndRuCl(PMe3)(PPh3) (8) TsCl
CpRuCl(PMe3)(PPh3) (9) TsCl
TpRuCl(PMe3)(PPh3) (10) TsCl
32.4
9.6
9
10
11
15.8
131
Cp*Ru(PPh3)2Cl (11)
TsCl
aAll reactions were performed in toluene-d8 at 60 °C using 1 mol % of
catalyst and 5 mol % of AIBN; the ratio of TsCl to styrene is 1.2:1. b TOF
is defined as (mol of product)/((mol of cat.) h), calculated at 50-65%
conversionofstyrene. c The yield isdeterminedby1H NMR spectroscopy
of product versus internal standard (hexamethylbenzene, 0.031 mmol).
conversion of styrene was observed, the yield of the mono-
adduct was considerably lower (Table 4, entries 7, 8, and 13).
This difference may be attributed to the formation of side
products such as oligomers/polymers.
It has been reported previously that the reactivity of the
catalyst is dependent on the Ru-P bond strength and largely
independent of the electronics of the phosphine.26 In our
case, Cp0Ru(PMe3)(PPh3)Cl complexes 7-10 showed
enhanced reactivity toward ATRA reactions as compared
to their PTA counterparts, which corresponds to the elec-
tron-donating ability of the phosphines (PMe3 > PTA).48
Exceptions were the most electron rich Cp* complexes 1 and
6; the addition of CCl4 to styrene catalyzed by 6 was slightly
slower than that for 1 (TOF = 933 h-1 versus TOF = 1060
h
-1; Table 4, entries 2 and 9).
For comparison purposes, we investigated the activity of
Cp0Ru(PPh3)2Cl complexes (11-15) toward the addition of
CCl4 to styrene under the same conditions as complexes
1-10 (Table 5, entries 1-5; compounds 11, 13, and 14 have
been previously reported as ATRA catalysts26,27). The
Cp0Ru(PPh3)2Cl complexes 11-15 all exhibited superior
(49) We have found that phosphine (PPh3) dissociation in these
complexes is slow in the absence of either AIBN or CCl4. Phosphine
dissociation is almost certainly necessary for catalysis; however, the
presence of radicals greatly increases the rate of dissociation. Harkrea-
der, J. L.; Frost, B. J. Unpublished results.
(50) A reviewer suggested that the lack of an induction period for the
addition of TsCl to styrene may be attributed to a reaction of TsCl with
PPh3. (See Watanabe, Y.; Mase, N.; Tateyama, M.; Toru, T. Tetra-
hedron: Asymmetry 1999, 10, 737-745.)
(48) (a) Tolman, C. A. Chem. Rev. 1977, 77, 313–348. (b) Darensbourg,
D. J.; Robertson, J. B.; Larkins, D. L.; Reibenspies, J. H. Inorg. Chem. 1999,
38, 2473–2481.

4688 Organometallics, Vol. 28, No. 16, 2009
Nair et al.
Table 8. Atom Transfer Radical Addition of CHCl3 to Styrene and of CCl4 to Hexene Catalyzed by Cp*Ru(PR3)(PPh3)Cl (PR3 = PTA,
PMe3, PPh3)a
entry
cat.
substrate
olefin
TOFb (h-1
)
time (h)
yieldc (%)
1d
2d
3d
3e
4e
6e
Cp*Ru(PTA)(PPh3)Cl (1)
Cp*Ru(PMe3)(PPh3)Cl (6)
Cp*Ru(PPh3)2Cl (11)
Cp*Ru(PTA)(PPh3)Cl (1)
Cp*Ru(PMe3)(PPh3)Cl (6)
Cp*Ru(PPh3)2Cl (11)
CHCl3
CHCl3
CHCl3
CCl4
CCl4
CCl4
styrene
styrene
styrene
hexene
hexene
hexene
28.2
62.6
272
202
53.3
100
4
3.5
2
4
7
4.5
>99
>99
93
93
>99
9255
a All reactions were performed at 60 °C using 1 mol % of catalyst and 5 mol % of AIBN. b TOF is defined as (mol of product)/((mol of cat.) h),
calculated at 50-65% conversion of styrene. c The yield is determined by 1H NMR spectroscopy of product versus internal standard. d 1.38 mmol of
styrene, with chloroform used as both solvent and substrate. e 1.38 mmol of hexene, 5.52 mmol of carbon tetrachloride, in toluene-d8.
reaction is almost completely inhibited upon addition of
excess phosphine.27,29a
Cp*Ru(PPh3)2Cl was the most active with a TTO of 92 000
after 40 h.54 Prior to this work the highest TTO value
reported for ATRA was 44 000 for the addition of CCl4 to
1-hexene.17
Severin and co-workers have recently reported that the
addition of AIBN is necessary for catalyst activity at low
catalyst loading.17 They proposed that AIBN allows for the
reduction of Cp0RuIII(PR3)Cl2 back to the active catalyst,
Cp0RuII(PR3)Cl.17 In the absence of AIBN a significant
decrease in the reaction rate was observed for Cp*Ru(PTA)-
(PPh3)Cl (TOF = 415 h-1; entry 3, Table 4), which is
comparable to that of Cp*Ru(PPh3)2Cl (TOF = 400 h-1).26
We observed a slight decrease in the time required to reach
>99% conversion as the [AIBN] was increased from 1 mol %
to 15 mol %. Above 15 mol % of AIBN no further increase in
the rate of reaction was observed.51
The RuCl2(PPh3)3-catalyzed addition of sulfonyl chlorides
to olefins has been reported by Kamagita and co-workers.52
We explored the efficiency of our catalytic system toward the
addition of p-toluenesulfonyl chloride (p-TsCl) to styrene
(Table 7). The reactivity order for complexes 1-5 was similar
to that observed for the addition of CCl4 to styrene, with the
exception of catalyst 3 (Table 7, entry 3). Unlike ATRA with
CCl4, the PMe3 complexes 6-10 exhibited lower reactivity
toward the addition of p-TsCl to styrene as compared to
their PTA analogues 1-5. Complex 3 exhibited a high TOF
(53.4 h-1) at short reaction time (∼50% conversion); how-
ever, activity leveled off at 90% conversion (Figure 7).53 Of
interest is the fact that reactions involving p-TsCl with styrene
exhibited no induction period.51
In conclusion, we found that the air-stable and readily
synthesized Cp0Ru(PPh3)(PR3)Cl complexes (Cp0 = Cp*,
Dp, Ind, Cp, Tp; PR3 = PTA, PMe3, PPh3) efficiently
catalyzed the atom transfer radical addition of CCl4 and
p-toluenesulfonyl chloride to styrene. The Cp* analogues
also catalyzed the addition of CHCl3 to styrene and of CCl4
to hexene. Catalyst performance appears to depend mainly
on the electron richness of the ruthenium center and on
the nature of the phosphine ligand. The pronounced elec-
tron-donating ability of Cp* rendered Cp*Ru(PPh3)2Cl
(11) an exceptional catalyst and both Cp*Ru(PTA)-
(PPh3)Cl (1) and its PMe3 counterpart (6) very effici-
ent ATRA catalysts (the order of reactivity is Cp*Ru .
DpRu > IndRu > CpRu >TpRu). The catalytic activity
of Cp0Ru(PTA)(PPh3)Cl and Cp0Ru(PMe3)(PPh3)Cl, how-
ever, is significantly reduced relative to the activity of the
parent Cp0Ru(PPh3)2Cl complexes. This indicates to us
that the efficiency of catalysis is hampered by replacement
of PPh3 with a more strongly binding phosphine such as
PTA or PMe3;a strong indication that phosphine disso-
ciation is involved in the reaction mechanism. This was further
confirmed by the lower catalytic activity of Cp0Ru(PTA)2Cl
complexes. The catalytic performance of the ruthenium com-
plexes may be further tuned by modifications of ancillary
ligands and phosphines and awaits further study.55
The Cp* complexes 1, 6, and 11 were the most active
catalysts among the series (1-11) for the addition of both
CCl4 and p-TsCl to styrene and were therefore explored for
the ATRA of the more challenging substrate, CHCl3
(Table 8, entries 1-3). Compound 11 was the most active,
with a TOF of 272 h-1 and 93% yield in 2 h. Compound 6
(TOF 62.6 h-1) has a faster initial rate with respect to 1 (TOF
28.2 h-1), as evidenced by the higher TOF (obtained at 50-
65% conversion), with both complexes yielding >99%
conversion at 60 °C in 3-4 h. Compounds 1, 6, and 11 are
also active for the addition of CCl4 to 1-hexene (Table 8,
entries 4-6). The Cp*Ru(PTA)(PPh3)Cl-catalyzed addition
of CCl4 to hexene proceeded rapidly with a TOF of 202 h-1
as compared to the PMe3 analogue (53.3 h-1) and PPh3
analogue (100 h-1). The TTO values obtained for the addi-
tion of CCl4 to hexene were impressive; with catalyst load-
ings of 0.001 mol %, Cp*Ru(PTA)(PPh3)Cl (1) exhibited
a TTO of 79 000 in 48 h, Cp*Ru(PMe3)(PPh3)Cl (6) was
more impressive with a TTO of 88 000 after 48 h, and
Acknowledgment. We gratefully acknowledge financial
support from the National Science Foundation CAREER
program (NSF Grant No. CHE-0645365). Financial support
from the NSF is also acknowledged for the X-ray and NMR
facilities (Grant Nos. CHE-0226402 and CHE-0521191).
The Korea Research Foundation (KRF-2007-357-C00056)
is acknowledged by T.H.K. for partial support.
Supporting Information Available: 31P{1H} and 1H NMR
spectra of all new compounds, kinetics plots of the catalytic
reactions, tables of full bond lengths and angles for compounds
1, 6, 9, and 10 as well as crystallographic data in CIF format.
This material is available free of charge via the Internet at http://
pubs.acs.org.
(54) The procedure was identical with that for the other catalytic runs
(Table 8, entries 4-6), except the catalyst loading was reduced to 0.001
mol %. Compound 1 yielded 79% conversion in 48 h, compound 6
provided 88% conversionin 48 h, and compound 11 yielded 92% in 40 h,
as determined by 1H NMR spectroscopy.
(55) Cp*Ru(PPh3)2Cl also catalyzes the reaction of CCl4 to hexene at
room temperature; a 41% yield is observed in 10 min at room tempera-
ture with no further reaction observed at longer times.
(51) See the Supporting Information for details.
(52) Kamigata, N.; Shimizu, T. Rev. Heteroat. Chem. 1997, 17, 1–50.
(53) The reaction could be brought to completion by addition of
excess of p-TsCl.