Group 4 transition-metal complexes of an aniline-carbene-phenol ligand

Article abstract of DOI:10.1021/om4001567

Attempts to install a tridentate aniline-NHC-phenol (NCO) ligand on titanium and zirconium led instead to complexes resulting from unexpected rearrangement pathways that illustrate common behavior in carbene-early- transition-metal chemistry.

Full text of DOI:10.1021/om4001567

Article
pubs.acs.org/Organometallics
Group 4 Transition-Metal Complexes of an Aniline−Carbene−Phenol
Ligand
Emmanuelle Despagnet-Ayoub,*,†,‡ Lawrence M. Henling,§ Jay A. Labinger,*,§ and John E. Bercaw*,§
†CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP 44099, F-31077 Toulouse Cedex 4, France
‡Universite
́
de Toulouse, UPS, INPT, F-31077 Toulouse Cedex 4, France
§Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California 91125,
United States
S
* Supporting Information
ABSTRACT: Attempts to install a tridentate aniline−NHC−phenol (NCO) ligand on titanium and zirconium led instead to
complexes resulting from unexpected rearrangement pathways that illustrate common behavior in carbene−early-transition-metal
chemistry.
-heterocyclic carbene ligands (NHC) have been utilized
(CNO) complex 3, the product that would be expected from 2
Nin many catalytic processes, especially with late- (Scheme 1).6 Apparently deprotonation accelerates the
transition-metal complexes.1 Their electronic propertiesthey
rearrangement process; accordingly, we decided to study routes
that avoid deprotonation, involving direct protonolysis of early-
transition-metal alkyl or amide complexes by the neutral
precursor 1.
are strong σ-donating, soft ligandsfavor the formation of
strong bonds with late-transition-metal centers, helping to
stabilize such catalysts. Those very properties tend to make
NHCs poorer ligands for hard centers such as early-transition-
metal complexes, from which they tend to dissociate relatively
easily;2 that weak bonding has even been exploited to generate
a Ti-based catalyst for ring-opening lactide polymerization.3 In
attempts to stabilize early-metal carbene complexes, tridentate
dianionic ligands with an NHC in the central position flanked
by anionic tethers have frequently proven a successful design
motif.4
RESULTS AND DISCUSSION
■
This approach was first tested in the metalation of a simpler
symmetrical (OCO) ligand (Scheme 2). Reaction of the
imidazolium precursor with tetrabenzylzirconium affording the
chlorobenzylzirconium complex, followed by addition of 1
equiv of benzyl Grignard reagent, gave the desired (OCO)-
ZrBn2 (4) in 35% yield. The 13C NMR spectrum reveals a peak
with a large downfield chemical shift (206 ppm) characteristic
of the carbene carbon. The X-ray structure (Figure 1) confirms
the binding mode of the (OCO) moiety as an LX2 type ligand;
the zirconium−carbene bond length (2.329 Å) is typical for this
type of interaction. One of the benzyl groups shows an
additional interaction between Zr and the ipso carbon (Zr−
C(39)−C(40) = 87.6° and Zr−C(40) = 2.68 Å), demonstrat-
ing the electrophilicity of the zirconium center.
Few examples of efficient NHC-based olefin polymerization
catalysts have been reported.4b,f−i,5 We recently reported the
synthesis of a potential precursor to a tridentate NHC ligand,
the imidazolium salt 1,6 and speculated that group 4 transition-
metal complexes of that C1-symmetrical (NCO) carbene ligand
might catalyze polymerization with tacticity control, by analogy
to the amine−pyridyl−phenyl (NNC) system reported by
Busico et al.7 We report here attempts to synthesize titanium
and zirconium complexes of our (NCO) ligand, which did not
lead to the target structures; instead, they highlight several
different rearrangement pathways that may occur in carbene−
early-transition-metal chemistry.
Imidazolium salt 1 is stable in the solid state, although it
rearranges slowly in solution (7 days at room temperature or 15
min at 90 °C, in THF) to the more stable benzimidazolium
species 2. Our first attempt at an (NCO) complex derived from
1, triple deprotonation followed by reaction of the dianionic
carbene with ZrCl4, gave instead the benzimidazolylidene
For protonolysis with the (NCO)-imidazolium precursor, we
first attempted reaction of 1 with TiCl2(NMe2)2, a route that
should have generated the (OCN)TiCl2 complex with
liberation of dimethylamine. Again the plan failed: instead, we
obtained zwitterionic 5, in which 1 had rearranged to produce a
bidentate (N,O) ligand coordinated to Ti and an open,
uncoordinated iminium group (Scheme 3). The rearrangement
Received: February 27, 2013
© XXXX American Chemical Society
A
dx.doi.org/10.1021/om4001567 | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 1. Rearrangement of the Aniline−NHC−Phenol Precursor 1
Scheme 2. Synthesis of Dibenzyl (OCO)-Carbene Complex
4
a rare example of an anionic titanium complex,9 was also
obtained more rationally, by direct reaction of TiCl2(NMe2)2
with the rearranged benzimidazolium−amino−phenol species 2
(Scheme 3).
Since nucleophilic attack by amine (or amide) leads to
opening of the N-heterocycle ring, we next examined the
reaction of 1 with ZrBn4, as the byproduct (toluene) should be
innocuous. Following the same procedure used in the
successful synthesis of (OCO)-complex 4, we obtained a
1
clean product, but clearly not the desired one: the H NMR
spectrum contained too many signals (six diastereotopic peaks
assigned to three benzyl methylene groups, as well as one at δ
4.4 integrating for one proton), while no carbene peak was
detected by 13C NMR. X-ray crystallography identified the
product as 7, in which a benzyl group and a proton have
migrated to the carbene, converting the heterocycle to an
imidazolidine (Scheme 4, Figure 3). Complex 7 features an
effectively tetradentate (N,N,N,O) dianionic ligand, interacting
with the metal center via two X-type (anilide and phenolate)
and two L-type (the two nitrogens of the imidazolidine) bonds.
The bonding parameters are similar to those of a reported
bis(amine)−bis(phenolate) zirconium complex.10
Migration of a benzyl ligand to an NHC was previously
reported for a chlorobenzylzirconium complex of a bis-
(phenolate)−carbene (OCO) ligand; the presence of a L-
type donor such as THF favored the migration.11 In our
system, the aniline arm which can act as a L-type ligand is
probably critical in the migration process, as confirmed by the
synthesis of the dibenzylbis(phenolate)imidazolylidene zirco-
nium complex 4. Since the preparation of our (OCO)−Zr
complex 4 was not accompanied by any such migration, we
propose the mechanism shown in Scheme 4, in which bidentate
(C,O) coordination of ligand 1 is followed by coordination of
the aniline arm as a L-type ligand, inducing the migration of
one benzyl group. Subsequent deprotonation of the aniline by
the carbene center and, finally, substitution of the chloride by
the benzyl Grignard would lead to 7.
Figure 1. Molecular structure of complex 4. Selected bond lengths (Å)
and angles (deg): Zr(1)−O(1) = 1.9847(8), Zr(2)−O(2) =
1.9902(8), Zr(1)−C(15) = 2.3290(11), Zr(1)−C(32) = 2.2857(12),
Zr(1)−C(39) = 2.3043(11), Zr(1)−C(40) = 2.6816(11); O(1)−
Zr(1)−C(15) = 77.64(4), O(1)−Zr(1)−O(2) = 154.48(3), C(39)−
Zr(1)−C(32) = 121.24(4), Zr(1)−C(32)−C(33) = 96.65(7), Zr(1)−
C(39)−C(40) = 87.64(7).
probably involves nucleophilic attack at the imidazolium
carbon, by either an amide ligand or a liberated amine,
followed by ring opening of the N-heterocycle. The crystal
structure of 5 (Figure 2a) exhibits slightly distorted octahedral
coordination, with bonding parameters similar to those in
previously reported phenolate−amine titanium complexes;8 the
Ti−Cl distances follow the expected trans-effect series (trans to
amine > trans to anilide > trans to phenolate).
Compound 5 slowly rearranges (overnight at 50 °C) to a
new species which, from NMR data (δH 10.61 ppm, δC 150.9
ppm), appears to contain an imidazolium moiety. The product
was crystallized and identified by X-ray diffraction as 6 (Figure
2b). (The quality of the structure determination (multiply
twinned with partial overlap added to poor integration) was
insufficient to determine accurate bond parameters, only to
establish connectivity.) Presumably 6 arises from ring-closing
replacement of the dimethylamide N with the anilide N
effectively the reverse of the process that led to 5. Zwitterion 6,
CONCLUSION
■
In conclusion, our several different attempts to generate the
desired (NCO)−group 4 metal complexes all failed, but by
(apparently) completely unrelated routes: ring opening of the
N-heterocycle of the NHC by nucleophilic attack in one case
and migration of alkyl to the carbene carbon in another. These
rearrangements were unexpected, since the synthesis of the
analogous (OCO) complex was straightforward, but they do
not appear to indicate any inherent instability of the target
structure or any obvious reason why a successful route cannot
be devised; efforts are continuing. In the meantime, our
understanding of these different decomposition pathways can
provide valuable guidelines for catalytic applications of NHC−
early-transition-metal complexes.
B
dx.doi.org/10.1021/om4001567 | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 3. Synthesis of Titanium Complexes 5 and 6
Figure 2. (a) Molecular structure of complex 5. Selected bond lengths (Å) and angles (deg): Ti(1)−N(1) = 1.9911(14), Ti(1)−O(1) = 1.8736(12),
Ti(1)−N(5) = 2.2208(13), Ti(1)−Cl(1) = 2.3860(5), Ti(1)−Cl(2) = 2.4031(5), Ti(1)−Cl(3) = 2.4355(5); N(1)−Ti(1)−O(1) = 78.96(5). (b)
Molecular structure of complex 6.
Scheme 4. Synthesis of Complex 7 by Benzyl Migration
chloride salt15 were prepared according to the published procedures.
Potassium hexamethyldisilazane and benzyl Grignard (1 M in ether)
EXPERIMENTAL SECTION
■
General Considerations. All experiments were performed using
conventional vacuum line and Schlenk tube techniques or in a
were purchased from Sigma Aldrich and used as received. Benzene-d6
and CD2Cl2 were degassed and passed through a plug of activated
glovebox under a nitrogen atmosphere. Solvents were dried by the
method of Grubbs.12 3-(3,5-Di-tert-butyl-2-hydroxyphenyl)-1-(2-
alumina prior to use. NMR spectra were recorded on Varian Mercury
(mesitylamino)phenyl)-4,5-dihydro-1H-imidazol-3-ium chloride (1),6
300, Varian INOVA 500, and Varian INOVA 600 spectrometers and
referenced to the solvent residual peak. Elemental analyses were
performed by Midwest Microlab LLC, Indianapolis, IN 46250, or
Robertson Microlit Laboratories, Ledgewood, NJ 07852.
3-(2-((3,5-di-tert-butyl-2-hydroxyphenyl)amino)ethyl)-1-mesityl-1H-
benzo[d]imidazol-3-ium chloride (2),6 TiCl2(NMe2)2,13 ZrBn4,14 and
N,N′-bis(2-hydroxy-3,5-di-tert-butylphenyl)-4,5-dihydroimidazolinium
C
dx.doi.org/10.1021/om4001567 | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
C36H54Cl3N5OTi 725.29, found 529.51. The complex was not stable
under the mass spectrum conditions; the mass found corresponds to
the iminium ligand (calcd for C34H49N4O 529.78). Anal. Calcd for
C36H54Cl3N5OTi·0.5CH2Cl2: C, 56.97; H, 7.20; N, 9.10. Found: C,
56.89; H, 7.38; N, 9.09.
Synthesis and Characterization of Titanium Complex 6. A
solution of complex 5 in methylene chloride was heated overnight at
50 °C to quantitatively yield complex 6 as a brown solid. Crystals of 6
can be obtained by cooling at −20 °C a solution of 6 in a CH2Cl2/
1
pentane mixture. H NMR (400 MHz, CD2Cl2, 25 °C): δ 10.61 (s,
1H, NCHN), 8.02 (m, 1H, CH), 7.79 (m, 1H, CH), 7.62 (m, 1H,
CH), 7.20 (m, 2H, CH), 7.06 (m, 2H, CH), 6.22 (s, 1H, CH), 5.48
(br s, 2H, NCH2), 4.98−4.63 (br s, 2H, NCH2), 4.10 (br s, 1H,
HNMe2), 2.91 (br s, 3H, NMe2), 2.63 (br s, 3H, NMe2), 2.41 (br s,
3H, CH3), 1.63 (br s, 6H, CH3), 1.16 (s, 9H, tBu), 0.55 (s, 9H, tBu).
1H NMR (500 MHz, CD2Cl2, −30 °C): δ 10.56 (s, 1H, NCHN), 8.01
(d, J = 8.3 Hz, 1H, CH), 7.82 (pt, J = 7.8 Hz, 1H, CH), 7.66 (m, 1H,
CH), 7.21 (m, 1H, CH), 7.04 (m, 2H, CH), 7.00 (s, 1H, CH), 6.14 (s,
1H, CH), 5.70 (m, 1H, NCH2), 5.51 (m, 1H, NCH2), 4.96 (m, 1H,
NCH2), 4.16 (m, 1H, HNMe2), 3.84 (m, 1H, NCH2), 3.04 (d, J = 6.2
Hz, 3H, HNMe2), 3.00 (d, J = 6.2 Hz, 3H, HNMe2), 2.34 (s, 3H,
CH3), 1.82 (s, 3H, CH3), 1.32 (s, 3H, CH3), 1.12 (s, 9H, tBu), 0.46 (s,
9H, tBu). 13C NMR (125 MHz, CD2Cl2, −30 °C): δ 150.9 (C), 150.2
(C), 145.0 (C), 143.8 (NCHN), 141.6 (C), 135.6 (C), 134.9 (C),
131.7 (C), 131.1 (C), 130.0 (CH), 129.8 (CH), 128.2 (CH), 128.1
(CH), 128.0 (CH), 127.5 (C), 117.7 (CH), 113.9 (CH), 112.8 (CH),
52.3 (NCH2), 50.8 (NCH2), 43.6 (NMe2), 43.1 (NMe2), 33.8 (CtBu),
33.6 (CtBu), 30.5 (CHtBu), 29.1 (CHtBu), 21.0 (CH3), 17.5 (CH3), 16.5
(CH3). MS (FAB+): m/z calcd for C34H47Cl3N4OTi 682.22, found
484.33. The complex was not stable under the mass spectrum
conditions, the mass found corresponds to the benzimidazolium ligand
(calcd for C34H42N3O 484.33). Anal. Calcd for C34H47Cl3N4OTi: C,
59.88; H, 6.95; N, 8.22. Found: C, 59.20; H, 7.23; N, 8.22.
Figure 3. Molecular structure of complex 7. Selected bond lengths (Å)
and angles (deg): Zr(1)−N(1) = 2.397(2), Zr(1)−N(2) = 2.439(2),
Zr(1)−N(3) = 2.117(2), Zr(1)−O(1) = 2.0518(18); N(3)−Zr(1)−
N(2) = 70.22(8), O(1)−Zr(1)−N(1) = 69.84(7), N(1)−Zr(1)−N(2)
= 53.81(7), C(47)−Zr(1)−C(40) = 86.50(10), Zr(1)−C(47)−C(48)
= 115.00(18), Zr(1)−C(40)−C(41) = 136.9(2).
Synthesis and Characterization of (OCO)ZrBn2 (4). To a
suspension of N,N′-bis(2-hydroxy-3,5-di-tert-butylphenyl)-4,5-dihy-
droimidazolinium chloride salt (50 mg, 0.097 mmol) in toluene (5
mL) was added a solution of ZrBn4 (44 mg, 0.097 mmol) in toluene
(5 mL). After 2 h, benzyl Grignard (96 μL, 0.096 mmol) was added
and the mixture was stirred for 1 h. The reaction mixture was then
filtered through Celite and evaporated to dryness. After several washes
with pentane, complex 4 was obtained as a yellow powder (32 mg,
35%). 1H NMR (500 MHz, C6D6): δ 7.50 (d, J = 2.3 Hz, 2H,
CHPhOH), 6.98 (d, J = 7.5 Hz, 4H, CHBn), 6.86 (t, J = 7.5 Hz, 4H,
CHBn), 6.74 (d, J = 2.3 Hz, 2H, CHPhOH), 6.61 (t, J = 7.5 Hz, 2H,
CHBn), 3.24 (s, 4H, NCH2), 2.42 (s, 4H, CH2Ph), 1.82 (s, 18H, tBu),
1.46 (s. 18H, tBu). 13C NMR (125 MHz, C6D6): δ 205.9 (Ccarbene),
148.4 (C), 140.4 (C), 139.4 (C), 137.6 (C), 132.1 (C), 129.4 (CH),
129.3 (CH), 122.4 (CH), 119.2 (CH), 112.3 (CH), 55.6 (CH2Ph),
47.7 (NCH2), 36.2 (CtBu), 34.9 (CtBu), 32.2 (CH3,tBu), 30.6 (CH3,tBu).
Anal. Calcd for C45H59N2O2Zr: C, 71.95; H, 7.92; N, 3.73. Found: C,
72.20; H, 7.80; N, 3.44.
Synthesis and Characterization of (NNNO)ZrBn2 (7). To a
suspension of imidazolium 1 (50 mg, 0.096 mmol) in toluene (5 mL)
was added a solution of ZrBn4 (44 mg, 0.096 mmol) in toluene (5
mL). After 2 h, benzyl Grignard (96 μL, 0.096 mmol) was added and
the mixture stirred for 1 h. The reaction mixture was then evaporated
to dryness, and the residue was solubilized in pentane. After filtration
through Celite, the solution was concentrated and stored in the
refrigerator; a yellow solid precipitated, yielding complex 7 (47 mg,
1
52%). H NMR (500 MHz, C6D6): δ 7.45 (d, J = 2.3 Hz, 1H, CH),
7.11 (m, 2H, CH), 7.02 (m, 4H, CH), 6.93−6.81 (m, 9H, CH), 6.68−
6.61 (m, 4H, CH), 6.07 (d, J = 8.2 Hz, 1H, CH), 5.91 (dd, J = 7.7 Hz,
J = 1.8 Hz, 2H, CH), 4.48 (t, J = 3.4 Hz, 1H, NCHBnN), 3.01 (m, 1H,
NCH2), 2.93 (m, 1H, NCH2), 2.87 (m, 1H, NCH2), 2.78 (m, 1H,
NCH2), 2.65 (d, J = 11.9 Hz, 1H, CH2Ph), 2.55 (d, J = 11.2 Hz, 1H,
CH2Ph), 2.43 (dd, J = 11.5, 9.2 Hz, 2H, CH2Ph), 2.37 (dd, J = 14.7,
3.8 Hz, 1H, CH2Ph), 2.26 (dd, J = 14.7, 2.9 Hz, 1H, CH2Ph), 2.21 (s,
3H, CH3,Mes), 2.16 (s, 3H, CH3,Mes), 1.73 (s, 3H, CH3,Mes), 1.55 (s, 9H,
tBu), 1.37 (s, 9H, tBu). 13C NMR (125 MHz, C6D6): δ 159.6 (C),
153.9 (C), 151.0 (C), 148.8 (C), 142.1 (C), 140.3 (C), 138.8 (C),
136.9 (C), 136.9 (C), 135.3 (C), 134.5 (C), 131.3 (CH), 130.1 (CH),
129.2 (CH), 129.1 (C), 128.8 (CH), 128.6 (CH), 128.6 (CH), 128.4
(CH), 128.1 (CH), 126.7 (CH), 126.8 (CH), 126.7 (CH), 123.3
(CH), 122.1 (CH), 120.8 (C), 120.3 (CH), 116.1 (CH), 114.7 (CH),
113.42 (CH), 77.6 (CH2Ph), 70.3 (CH2Ph), 69.2 (NCHBnN), 43.6
(NCH2), 42.6 (NCH2), 35.4 (CtBu), 34.6 (CtBu), 31.9 (CH3,tBu), 30.5
(CH3,tBu), 29.6 (CH2PhNCHN), 21.0 (CH3,Mes), 18.9 (CH3,Mes), 18.8
(CH3,Mes). Anal. Calcd for C53H61N3OZr: C, 75.13; H, 7.26; N, 4.96.
Found: C, 74.80; H, 6.90; N, 5.14.
Synthesis and Characterization of Titanium Complex 5. A
solution of TiCl2(NMe2)2 (16 mg, 0.077 mmol) in methylene chloride
(2 mL) was added to a solution of imidazolium salt 1 (40 mg, 0.077
mmol) in methylene chloride (5 mL). After it was stirred for 1 h, the
solution was evaporated to dryness to quantitatively yield complex 5 as
a brown solid. Crystals of 5 can be obtained by cooling at −20 °C a
1
solution of 5 in a CH2Cl2/pentane mixture. H NMR (600 MHz,
CD2Cl2): δ 9.02 (s, 1H, NCHN), 7.30 (dd, J = 7.7 Hz, J = 1.4 Hz, 1H,
CH), 7.14 (td, J = 8.3 Hz, J = 1.4 Hz, 1H, CH), 6.97 (m, 2H, CH),
6.73 (td, J = 7.7 Hz, J = 1.2 Hz, 1H, CH), 6.49 (d, J = 1.6 Hz, 1H,
CH), 6.27 (br s, 1H, NH), 6.13 (dd, J = 8.3 Hz, J = 1.2 Hz, 1H, CH),
5.57 (br s, 1H, CH), 4.39 (m, 2H, NCH2), 3.92 (br s, 1H, NCH2),
3.65 (br s, 1H, NCH2), 3.36 (s, 3H, NMe2), 2.83 (br s, 6H, HNMe2),
2.68 (s, 3H, NMe2), 2.47 (br s, 1H, HNMe2), 2.29 (s, 3H, CH3Mes),
2.19 (br s, 3H, CH3Mes), 1.97 (br s, 3H, CH3Mes), 1.16 (s, 9H, tBu),
1.14 (s, 9H, tBu). 13C NMR (151 MHz, CD2Cl2): δ 157.9 (NCHN),
150.7 (C), 145.6 (C), 142.5 (C), 136.6 (C), 136.7 (C), 133.3 (C),
131.4 (C), 131.2 (CH), 129.3 (CH), 127.8 (CH), 123.4 (C), 117.9
(CH), 117.5 (C), 116.8 (CH), 112.6 (CH), 102.2 (CH), 50.7
(NCH2), 49.2 (NCH2), 46.7 (NMe2), 42.2 (HNMe2), 37.9 (NMe2),
35.2 (CtBu), 34.4 (CtBu), 31.2 (CHtBu), 29.2 (CHtBu), 20.7 (CH3,Mes),
18.4 (CH3,Mes), 18.1 (CH3,Mes). MS (FAB+): m/z calcd for
ASSOCIATED CONTENT
■
S
* Supporting Information
Tables, figures, and CIF files giving crystallographic data. This
material is available free of charge via the Internet at http://
pubs.acs.org.
D
dx.doi.org/10.1021/om4001567 | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(15) (a) Min, K. S.; Weyermuller, T.; Bothe, E.; Wieghardt, K. Inorg.
Chem. 2004, 43, 2922−2931. (b) Waltman, A. W.; Grubbs, R. H.
Organometallics 2004, 23, 3105−3107.
AUTHOR INFORMATION
Corresponding Author
*E-mail: ayoub@lcc-toulouse.fr (E.D.-A.); jal@caltech.edu
(J.A.L.); bercaw@caltech.edu (J.E.B.).
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by a KAUST Center-In-Development
Grant to King Fahd University of Petroleum and Minerals
(Dhahran, Saudi Arabia) and the USDOE Office of Basic
Energy Sciences (Grant No. DE-FG03-85ER13431). The
Bruker KAPPA APEXII X-ray diffractometer was purchased
via an NSF CRIF:MU award to the California Institute of
Technology (CHE-0639094).
REFERENCES
■
(1) (a) Correa, A.; Nolan, S. P.; Cavallo, L. Top. Curr. Chem. 2011,
302, 131−155. (b) Ces
Chem. Soc. Rev. 2004, 33, 619−636. (c) Glorius, F. Top. Organomet.
́
ar, V.; Bellemin-Laponnaz, S.; Gade, L. H.
̈
Chem. 2007, 21, 1−20. (d) Bourissou, D.; Guerret, O.; Gabbaı, F.;
Bertrand, G. Chem. Rev. 2000, 100, 39−91. (e) Cesar, V.; Gade, L. H.;
Bellemin-Laponnaz, S. RSC Catal. Ser. 2011, 6, 228−251. (f) Díez-
Gonzalez, S.; Nicolas Marion, N.; Nolan, S. P. Chem. Rev. 2009, 109,
́
́
3612−3676.
(2) Schaper, L.-A.; Tosh, E.; Herrmann, W. A. RSC Catal. 2011, 6,
166−195.
(3) Patel, D.; Liddle, S. T.; Mungur, S. A.; Rodden, M.; Blake, A. J.;
Arnold, P. L. Chem. Commun. 2006, 1124−1126.
(4) (a) Spencer, L. P.; Beddie, C.; Hall, M. B.; Fryzuk, M. D. J. Am.
Chem. Soc. 2006, 128, 12531−12543. (b) Spencer, L. P.; Fryzuk, M. D.
J. Organomet. Chem. 2005, 690, 5788−5803. (c) Romain, C.; Brelot,
L.; Bellemin-Laponnaz, S.; Dagorne, S. Organometallics 2010, 29,
1191−1198. (d) Romain, C.; Heinrich, B.; Bellemin-Laponnaz, S.;
Dagorne, S. Chem. Commun. 2012, 48, 2213−2215. (e) Bellemin-
Laponnaz, S.; Welter, R.; Brelot, L.; Dagorne, S. J. Organomet. Chem.
2009, 694, 604−606. (f) Aihara, H.; Matsuo, T.; Kawaguchi, H. Chem.
Commun. 2003, 2204−2205. (g) Zhang, D.; GengShi, G.; Wang, J.;
Yue, Q.; Zheng, W.; Weng, L. Inorg. Chem. Commun. 2010, 13, 433−
435. (h) Zhang, D.; Liu, N. Organometallics 2009, 28, 499−505.
(i) Bocchino, C.; Napoli, M.; Costabile, C.; Longo, P. J. Polym. Sci.,
Part A: Polym. Chem. 2011, 49, 862−870.
(5) McGuinness, D. S. Dalton Trans. 2009, 6915−6923.
(6) Despagnet-Ayoub, E.; Miqueu, K.; Sotiropoulos, J. M.; Henling,
L. M.; Day, M. W.; Labinger, J. A.; Bercaw, J. E. Chem. Sci. 2013, 4,
2117−2121.
(7) Boussie, T. R.; Diamond, G. M.; Goh, C.; Hall, K. A.; Lapointe,
A. M.; Leclerc, M. K.; Murphy, V.; Schoemaker, J. A. W.; Turner, H.;
Rosen, R. K.; Stevens, J. C.; Alfano, F.; Busico, V.; Cipullo, R.;
Talarico, G. Angew. Chem., Int. Ed. 2006, 45, 3278−3283.
(8) Blackmore, K. J.; Sly, M. B.; Haneline, M. R.; Ziller, J. W.;
Heyduk, A. F. Inorg. Chem. 2008, 47, 10522−10532.
(9) (a) Kopf, H.; Lange, K.; Pickardt, J. J. Organomet. Chem. 1991,
̈
420, 345−352. (b) Gainsford, G. J.; Kemmitt, T.; Lensink, C.;
Milestone, N. B. Inorg. Chem. 1995, 34, 746−748. (c) Lundmark, P. J.;
Kubas, G. J.; Scott, B. L. Organometallics 1996, 15, 3631−3633.
(d) Alonso, P. J.; Falvello, L. R.; Fornies
́
, J.; García-Monforte, M. A.;
Menjon
́
, B. Angew. Chem., Int. Ed. 2004, 43, 5225−5228.
(10) Tshuva, E. Y.; Goldberg, I.; Kol, M. J. Am. Chem. Soc. 2000, 122,
10706−10707.
(11) Romain, C.; Miqueu, K.; Sotiropoulos, J.-M.; Bellemin-
Laponnaz, S.; Dagorne, S. Angew. Chem., Int. Ed. 2010, 49, 2198−2201.
(12) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518−1520.
(13) Benzing, E.; Kornicker, W. Chem. Ber. 1961, 94, 2263−2267.
(14) Zucchini, U.; Albizzati, E.; Giannini, U. J. Organomet. Chem.
1971, 26, 357−372.
E
dx.doi.org/10.1021/om4001567 | Organometallics XXXX, XXX, XXX−XXX