Syntheses of Molybdenum Oxo Benzylidene Complexes

Article abstract of DOI:10.1021/jacs.8b09616

The reaction between Mo(O)(CHAr_o)(OR_F6)₂(PMe₃) (Ar_o = ortho-methoxyphenyl, OR_F6 = OCMe(CF₃)₂) and 2 equiv of LiOHMT (OHMT = O-2,6-(2,4,6-Me₃C₆H₂)₂C₆H₃) leads to Mo(O)(CHAr_o)(OHMT)₂, an X-ray structure of which shows it to be a trigonal bipyramidal anti benzylidene complex in which the o-methoxy oxygen is coordinated to the metal trans to the apical oxo ligand. Addition of 1 equiv of water (in THF) to the benzylidyne complex, Mo(CAr_p)(OR)₃(THF)₂ (Ar_p = para-methoxyphenyl, OR = OR_F6 or OC(CF₃)₃ (OR_F9)) leads to formation of {Mo(CAr_p)(OR)₂(μ-OH)(THF)}₂(μ-THF) complexes. Addition of 1 equiv of a phosphine (L) to Mo(CAr_p)(OR_F9)₃(THF)₂ in THF, followed by addition of 1 equiv of water, all at room temperature, yields Mo(O)(CHAr_p)(OR_F9)₂(L) complexes in good yields for several phosphines (e.g., PMe₂Ph (69% by NMR), PMePh₂ (59%), PEt₃ (69%), or P(i-Pr)₃ (65%)). The reaction between Mo(O)(CHAr_p)(OR_F9)₂(PEt₃) and 2 equiv of LiOHMT proceeds smoothly at 90 °C in toluene to give Mo(O)(CHAr_p)(OHMT)₂, a four-coordinate syn alkylidene complex. Mo(O)(CHAr_p)(OHMT)₂ reacts with ethylene (1 atm in C₆D₆) to give (in solution) a mixture of Mo(O)(CHAr_p)(OHMT)₂, Mo(O)(CH₂)(OHMT)₂, and an unsubstituted square pyramidal metallacyclobutane complex, Mo(O)(CH₂CH₂CH₂)(OHMT)₂, along with ethylene and Ar_pCH=CH₂. Mo(O)(CHAr_p)(OHMT)₂ also reacts with 2,3-dicarbomethoxynorbornadiene to yield syn and anti isomers of the "first-insertion" products that contain a cis C=C bond.

Full text of DOI:10.1021/jacs.8b09616

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Communication
Syntheses of Molybdenum Oxo Benzylidene Complexes
Feng Zhai, Konstantin V. Bukhryakov, Richard R. Schrock, Amir H. Hoveyda, Charlene Tsay, and Peter Müller
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.8b09616 • Publication Date (Web): 08 Oct 2018
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Syntheses of Molybdenum Oxo Benzylidene Complexes
†
Feng Zhai,‡ Konstantin V. Bukhryakov,‡ Richard R. Schrock,‡ Amir H. Hoveyda, Charlene Tsay,‡ and Peter
Müller‡
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‡Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
†Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467
ABSTRACT: The reaction between Mo(O)(CHAro)(ORF6)2(PMe3) (Aro = ortho-methoxyphenyl, ORF6 = OCMe(CF3)2) and
two equivalents of LiOHMT (OHMT = O-2,6-(2,4,6-Me3C6H2)2C6H3) leads to Mo(O)(CHAro)(OHMT)2, an X-ray structure
of which shows it to be a trigonal bipyramidal anti benzylidene complex in which the o-methoxy oxygen is coordinated
to the metal trans to the apical oxo ligand. Addition of one equivalent of water (in THF) to the benzylidyne complex,
Mo(CArp)(OR)3(THF)2 (Arp = para-methoxyphenyl, OR = ORF6 or OC(CF3)3 (ORF9)) leads to formation of
{Mo(CArp)(OR)2(-OH)(THF)}2(-THF) complexes.
Addition of one equivalent of
a
phosphine (L) to
Mo(CArp)(ORF9)3(THF)2 in THF, followed by addition of one equivalent of water, all at room temperature, yields
Mo(O)(CHArp)(ORF9)2(L) complexes in good yields for several phosphines (e.g., PMe2Ph (69% by NMR), PMePh2 (59%),
PEt3 (69%), or P(i-Pr)3 (65%)). The reaction between Mo(O)(CHArp)(ORF9)2(PEt3) and two equivalents of LiOHMT
proceeds smoothly at 90 °C in toluene to give Mo(O)(CHArp)(OHMT)2, a four-coordinate syn alkylidene complex.
Mo(O)(CHArp)(OHMT)2 reacts with ethylene (1 atm in C6D6) to give (in solution) a mixture of Mo(O)(CHArp)(OHMT)2,
Mo(O)(CH2)(OHMT)2,
and
an
unsubstituted
square
pyramidal
metallacyclobutane
complex,
Mo(O)(CH2CH2CH2)(OHMT)2, along with ethylene and ArpCH=CH2. Mo(O)(CHArp)(OHMT)2 also reacts with 2,3-
dicarbomethoxynorbornadiene to yield syn and anti isomers of the "first-insertion" products that contain a cis C=C bond.
The neopentylidyne ligand in (t-BuCH2)3MC-t-Bu (M =
W1 or Mo2) complexes is formed through what amounts to an
intramolecular deprotonation of an  carbon atom in one alkyl
ligand by another in some multialkyl intermediate to give an
alkylidene first,3 followed by a second (more facile) 
deprotonation of that alkylidene by an alkyl to give the
alkylidyne.4 Synthesis of MC-t-Bu)(1,2-dimethoxyethane)Cl3
and MC-t-Bu)(OR)3 complexes (OR is a sterically demanding
alkoxide or aryloxide) and the demonstration that the latter are
initiators for catalytic alkyne metathesis5 led to the development
of four-coordinate alkene metathesis initiators of the type
M(NR')CHR'')(OR)2 (M = Mo or W).6,7 Synthetic routes to
imido alkylidene complexes of Mo and W are based on a single
 hydrogen abstraction/deprotonation reaction in a dineopentyl
or dineophyl complex.8 Syntheses of oxo alkylidenes, which
have been proposed to be the type of alkene metathesis catalysts
present in "classical" heterogeneous catalyst systems,9 by
analogous methods have been more challenging. Tungsten oxo
alkylidene complexes were prepared through  hydrogen
abstraction in tungsten dialkyls in 2012,10 but syntheses of
molybdenum oxo alkylidene complexes that are active for
metathesis of olefins have remained elusive.11. Recently we
began to explore the synthesis of Mo oxo alkylidene complexes
through addition of water to alkylidyne complexes.7,12
(This is a rare example of a controlled hydrolysis of a high
oxidation state alkylidene or alkylidyne.13,14) Addition of
PMe3 to {Mo(CAro)(ORF6)2(-OH)}2(-dme) led to
formation of Mo(O)(CHAro)(ORF6)2(PMe3), from which
Mo(O)(CHAro)Cl2(PMe3)
and
Mo(O)(CHAro)(OHIPT)Cl(PMe3) (OHIPT = O-2,6-(2,4,6-i-
Pr3C6H2)2C6H3 15) were prepared. In the presence of
B(C6F5)3 Mo(O)(CHAro)(OHIPT)Cl(PMe3) was shown to
be active for the stereoselective ring-opening metathesis
polymerization of 2,3-dicarbomethoxynorbornadiene
(DCMNBD) and rac-2,3-dicarbomethoxy-5-norbornene
(DCMNBE), and the homocoupling of 1-decene to 9-
octadecene, consistent with analogous reactions that use
tungsten-based initiators16 and with removal of PMe3 to
form active metathesis initiators. Important questions are
whether an ortho-methoxy group in the benzylidyne and
benzylidene ligands is required for a controlled reaction
involving water and an alkylidyne complex and whether
phosphine-free complexes that are active for olefin
metathesis can be prepared and isolated . Some answers
to these questions are provided in this communication.
The synthesis and stability of W(O)(CH-t-
Bu)(OHMT)2 (OHMT = O-2,6-(2,4,6-Me3C6H2)2C6H3 or
hexamethylterphenoxide17)10a suggested that the phosphine-
free target should be Mo(O)(CHAro)(OHMT)2 (1-Aro); it was
prepared from Mo(O)(CHAro)(ORF6)2(PMe3) as shown in
eq 1. Trimethylphosphine is lost in the process as a
Addition
of
one
equiv
of
water
to
Mo(CAro)(ORF6)3(dme) (Aro
=
ortho-methoxyphenyl)
gives the dimeric benzylidyne hydroxo complex,
{Mo(CAro)(ORF6)2(-OH)}2(-dme) in which each
bridging hydroxo proton is hydrogen-bonded to the ortho
methoxy oxygen in the o-methoxybenzylidyne ligand.
consequence
of
steric
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OMe
MeO
OMe
1
2
3
4
THF
THF
H2O (1 equiv)
THF (2.2 equiv)
LiOHMT (2.3 equiv)
O
O
H
O
H
O
(1)
O
RF6
O
(2)
0.5
ORF6
Mo
O
toluene
100 °C, 1 h
O
CH2Cl2
- 40 °C to rt, 1 h
O
PMe3
Mo
Mo
RF6
O
Mo THF
ORF6
RF6
RF6
O
ORF6
ORF6
RF6
O
5
O
- 2 LiORF6 - PMe3
O
THF
- RF6OH
6
1-Aro; 37%
7
2-ArpF6; 70% yield (isolated)
8
9
pentane and CH2Cl2 at – 40 °C in the presence of several
equivalents of THF and isolated in 70% yield as pale red
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crystals.
Similar
reactions
starting
with
Mo(CArp)(ORF6)3(dme) and one equivalent of water (in THF)
also led to 2-ArpF6, but in poor yield (~10%), while addition of
water in dme to Mo(CArp)(ORF6)3(dme) did not lead to an
isolable benzylidyne hydroxo complex. Dme appears to be
detrimental and THF beneficial for formation of benzylidyne
hydroxo complexes in these circumstances.
Figure 1. A drawing of the structure of 1-Aro; Mo1-C1 =
1.933(2) Å, Mo1-O2 = 1.6698(14) Å, Mo1-O1 = 2.4865(17) Å,
Mo1-O3 = 1.915(2) Å, Mo1-O4 = 1.9295(15) Å.
hindrance overall in combination with binding of the
methoxide oxygen in the Aro group in the anti alkylidene
to the metal trans to the oxo ligand, as shown through an
X-ray study (Fig 1; see SI). The  value18 (0.78) suggests
that the configuration at the metal is closest to a trigonal
bipyramid (O2-Mo1-O1 = 166.27(7)°). Alkylidene proton
resonances were observed in the initial proton NMR
spectrum of 1-Aro at 11.92 ppm for the anti isomer (97%,
JCH = 156 Hz), the isomer found in the solid state (Fig 1),
and at 12.02 ppm for the syn isomer (JCH = 134 Hz), in
which the alkylidene has rotated19 by 180° and the
methoxide is not bound to the metal. After 1 h at 50 °C an
85:15 equilibrium ratio of anti to syn isomers was
observed.
Preliminary studies showed that the rate of reaction
of 1-Aro with ethylene is slow, perhaps because the lower
energy "methoxy-bound" anti form only slowly converts
to the more reactive syn form. We therefore turned to a
synthesis of the p-methoxybenzylidene analog where
intramolecular binding of the methoxy oxygen is not
possible.
Figure 2. End view of the structure of 2-ArpF6.
An X-ray study of 2-ArpF6 (Fig 2) shows its structure to be
analogous
to
that
of
previously
reported12
{Mo(CAro)(ORF6)2(-OH)}2(-dme) with one of the THFs
bridging the two Mo centers and one THF hydrogen-bonded to
each of the two bridging hydroxos. The OH...O angles and O...O
distances are consistent with a "classical" hydrogen bond
between the bridging hydroxo protons and THF oxygens.23 The
hydroxo proton resonance in 2-ArpF6 is found at 6.60 ppm in
the proton NMR spectrum in CD2Cl2 (cf. 9.30 ppm for the
hydroxo protons in {Mo(CAro)(ORF6)2(-OH)}2(-dme)).
The Mo-O distance to the bridging THF is 2.485(2) Å. The Mo-
C-Cipso angles are 179.4(2)°, in contrast to 168.57(7)° and
167.33(7)° in {Mo(CAro)(ORF6)2(-OH)}2(-dme), which
The
para-methoxybenzylidyne
complex,
Mo(CArp)(dme)Br3 was prepared by the "low oxidation state"
result
from
the
procedure.20 From it Mo(CArp)(ORF6)3(dme)21 and
Mo(CArp)(ORF6)3(THF)2
hydroxo protons being hydrogen bonded to the o-
methoxy
22
were
prepared
without
complications. Addition of one equivalent of water (in THF,
diethyl ether, or dichloromethane) to Mo(CArp)(ORF6)3(THF)2
led to the formation of {Mo(CArp)(ORF6)2(-OH)}2(THF)3 (2-
ArpF6) in good yield (eq 2). It was crystallized from a mixture
of
oxygens in the Aro group instead of to THF, as found in
2-ArpF6. Other distances and angles are not unusual (see SI).
In solution, proton NMR resonances for the bridging THF are
distinct from those for the hydrogen-bonded THFs or THF in
solution. The hydrogen-bonded THFs are readily lost from
solid
samples,
especially
in
vacuo,
to
give
{Mo(CArp)(ORF6)2(-OH)}2(-THF), and exchange rapidly
on the NMR scale with free THF in solution, as shown through
proton NMR studies. Addition of dioxane to an NMR sample
of {Mo(CArp)(ORF6)2(-OH)}2(-THF) led to formation of a
mixture of the -THF (OH at 6.63 ppm) and -dioxane (OH at
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proton resonance is found at 11.20 ppm (in C6D6) with JCH
6.51 ppm) complexes.
=
1
2
3
4
5
6
7
8
130 Hz, consistent with the alkylidene being in the syn
conformation. The corresponding anti isomer was not found in
solution even upon heating a sample of 1-Arp at 100 °C, which
suggests that coordination of an ortho methoxide in 1-Aro (Fig
1) stabilizes the anti form. The OHMT ligands in the proton
NMR spectrum at 22 °C are equivalent on the NMR time
scale through mirror symmetry. The purple color of 1-Arp
(λmax = 532 nm with ε532 ~ 400) is unusual for a "d0" complex
of this general type. We propose that the purple color arises
Addition of one equivalent of water (in THF) to
Mo(CArp)(ORF9)3(THF)2 in CH2Cl2 led to formation of
{Mo(CArp)(ORF9)2(-OH)}2(-THF), which could be isolated
in 43 % yield as lime-green crystals; in the presence of
additional THF it crystallizes as {Mo(CArp)(ORF9)2(-
OH)(THF)}2(-THF) (2-ArpF9). An X-ray structural study
showed its structure to be entirely analogous to that for 2-ArpF6
(see SI for details). The two molecules of hydrogen-bonded
THF in 2-ArpF9 again are lost readily from solid samples,
especially in vacuo. The -OH resonance is found at 8.21 ppm
in 2-ArpF9 in CD2Cl2 (cf. 6.60 ppm in 2-ArpF6).
9
from
a weak LMCT transition that involves the p-
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methoxybenzylidene ligand. Compound 1-Arp also was
prepared from 3-PMePh2 in 66% yield on a 500 mg scale at 70
°C in 3.5 h.
Reactions between 2-ArpF6 or 2-ArpF9 and PMe3 or PEt3
(L) do not yield Mo(O)(CHArp)(OR)2(L) complexes readily
and in high yield. However, addition of one equivalent of
L to Mo(CArp)(ORF9)3(THF)2, followed by addition of one
equivalent of water, all at room temperature in THF, yields
Mo(O)(CHArp)(OR)2(L) complexes (3) in good yields for
several phosphines L (e.g., PMe2Ph (69% by NMR), PMePh2
(59%), PEt3 (69%), or P(i-Pr)3 (65%)). For example,
Mo(O)(CHArp)(ORF9)2(PEt3) (3-PEt3) can be prepared in this
manner (eq 3). These results suggest that in most cases it is
best to avoid formation of bis(-OH) dimers. We propose
that THF discourages formation of a hydroxo benzylidyne
An X-ray structural study of 1-Arp (Fig 3) reveals that the
OHMT terphenyl groups are roughly "interlocked," as they are
in W(O)(CH2)(OHMT)2,10b although they rotate readily
around the Mo-O bonds on the NMR time scale in solution at
22 °C. The relevant distances and angles are similar to those in
1-Aro (see Fig 1 and SI). Together the two OHMT ligands
prevent PEt3 or PMePh2 from remaining bound to the metal in
the final product and also provide a significant degree of steric
protection against bimolecular decomposition reactions.
dimer
from
OMe
PEt3 (1 equiv),
then H2O (1 equiv),
all in THF
MeO
H
(3)
ORF9
PEt3
Mo ORF9
RF9
O
Mo THF
O
- 2 THF, - RF9OH
RF9
O
RF9
O
THF
3-PEt3; 57% yield (isolated)
monomeric Mo(CArp)(ORF9)2(OH)(THF)x (x unknown). We
also propose that the hydroxo proton migrates to the
benzylidyne
Mo(CArp)(ORF9)2(OH)(THF)x

carbon intramolecularly in intermediate
to give
Figure 3. A drawing of the structure of 1-Arp;
Mo1-C1 = 1.9004(13) Å, Mo1-O1 = 1.6803(10) Å, Mo1-O3 = 1.9064(9)
Å, Mo1-O4 = 1.9113(9) Å, Mo1-C1-Cipso = 137.42(10)°, Mo1-O3-Cipso
= 143.11(8)°, Mo1-O4-Cipso = 127.58(8)°.
Mo(O)(CHArp)(ORF9)2(THF)x, which is then trapped by L to
give Mo(O)(CHArp)(ORF9)2(L) complexes. Phosphines can
also bind to Mo in Mo(CArp)(ORF9)2(OH)(THF)x and help
prevent formation of -OH products and promote (perhaps
along with THF itself) migration of the proton from O to C.
Formation of ORF6 analogs of 3 at room temperature in THF
does not appear to be as successful, most likely because the
migrating proton is less acidic in ORF6 hydroxo
benzylidyne complexes. Studies that address multiple
mechanistic issues are ongoing.
Mo(O)(CHArp)(ORF9)2(PEt3) (3-PEt3) was chosen to
proceed further toward the goal of preparing a four-coordinate
complex. The reaction between 3-PEt3 and two equivalents of
LiOHMT proceeds smoothly at 90 °C in toluene over a period
of 1.5 h to give Mo(O)(CHArp)(OHMT)2 (1-Arp) which could
be isolated as plum-purple needles (eq 4). The alkylidene
Compound 1-Arp reacts with ethylene (1 atm in C6D6 at
22 °C) to give an orange solution that contains a mixture
of 1-Arp, Mo(O)(CH2)(OHMT)2, and an unsubstituted
metallacyclobutane
complex,
Mo(O)(CH2CH2CH2)(OHMT)2, along with ArpCH=CH2,
and ethylene, according to proton NMR studies. At a
molybdenum concentration of 17 mM in C6D6, the ratio
of Mo=CHArp : Mo=CH2 : Mo(C3H6) : ArpCH=CH2 is
57:5:38:43 (43% conversion) after 1.5 h. The 1:1:2:2
pattern of the four metallacycle proton resonances in
Mo(O)(CH2CH2CH2)(OHMT)2 at 2.92, 2.39, 1.68, and 0.45
ppm suggest that it has a square pyramidal structure.24
So far, efforts to isolate Mo(O)(CH2CH2CH2)(OHMT)2, an
analog of isolable W(O)(CH2CH2CH2)(OHMT)2,10b have
not been successful.
MeO
H
Mes
Mo
H
LiOHMT (2.2 equiv)
Mes
Mes
O
O
PEt3
Mo ORF9
(4)
Compound 1-Arp does not react readily with several
equivalents of Z-5-decene at 22 °C. It does react with 2,3-
dicarbomethoxynorbornadiene (4 equiv) to yield a 17:1
mixture of syn ( H at 11.63 ppm; eq 5) and anti isomers
(not shown in eq 5) of the first insertion product, each of
C6D6 or toluene
90 °C, 1.5 h
- PEt3 - 2 LiORF9
MeO
O
O
Mes
RF9
O
1-Arp; 71% yield (NMR);
44% isolated
3
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which contains a cis C=C bond.25 (The yield (by NMR) is
ACKNOWLEDGMENTS
1
2
3
4
5
6
7
8
~90%; see SI for details.) Both results are consistent with
a relatively sterically demanding coordination sphere
that limits access to an alkylidene, in contrast to
Mo(O)(CHAro)(OHIPT)Cl formed through removal of
PMe3 from Mo(O)(CHAro)(OHIPT)(PMe3)Cl, which
forms polymers from 2,3-dicarbomethoxynorbornadiene
readily.12
We are grateful for financial support from the National
Institutes of Health (GM-59426). We also thank the NSF for
support of X-ray diffraction instrumentation (CHE-0946721).
REFERENCES
(1) Clark, D. N.; Schrock, R. R. Multiple Metal–Carbon Bonds. 12.
Tungsten and Molybdenum Neopentylidyne and Some Tungsten
Neopentylidene Complexes. J. Am. Chem. Soc. 1978, 100, 6774–6776.
(2) (a) McCullough, L. G.; Schrock, R. R. Multiple Metal–Carbon
Bonds. 34. Metathesis of Acetylenes by Molybdenum(VI)
Alkylidyne Complexes. J. Am. Chem. Soc. 1984, 106, 4067–4068. (b)
McCullough, L. G.; Schrock, R. R.; Dewan, J. C.; Murdzek, J. S.
Multiple Metal-Carbon Bonds. 38. Preparation of
Trialkoxymolybdenum(VI) Alkylidyne Complexes, Their Reactions
with Acetylenes, and the X-ray Structure of
Mo[C3(CMe3)2][OCH(CF3)2]2(C5H5N)2. J. Am. Chem. Soc. 1985, 107,
5987–5998.
(3) Schrock, R. R. Alkylcarbene Complex of Tantalum by
Intramolecular -Hydrogen Abstraction. J. Am. Chem. Soc. 1974, 96,
6796–6797.
(4) Guggenberger, L. J.; Schrock, R. R. A Tantalum Carbyne
Complex. J. Am. Chem. Soc. 1975, 97, 2935.
OMe
OMe
CO2Me
CO2Me
CO2Me
MeO2C
9
O
O
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Mo
Mo
(5)
HMTO
HMTO
HMTO
HMTO
We conclude that the o-methoxy group is not required,
either for forming a benzylidene ligand from a benzylidyne
ligand or for stabilizing a bis(OHMT) oxo benzylidene
complex. The most successful syntheses of oxo alkylidene
complexes involve intramolecular  proton migrations
from O to C, where C is the benzylidyne  carbon, and are
most successful when OR is ORF9, the solvent is THF, and
a phosphine is available to trap the oxo benzylidene
product and possibly help form it. Several phosphine
adducts of molybdenum oxo benzylidene complexes are
accessible via reactions between Mo(CArp)(OR)3(THF)2
complexes and water. We can now predict that other
(5) Schrock, R. R. in Handbook of Metathesis, Grubbs, R. H., Ed.,
Wiley-VCH, Weinheim, 2003, p. 173–189.
(6) (a) Schrock, R. R. in Handbook of Metathesis, Grubbs, R. H., Ed.,
Wiley-VCH, Weinheim, 2003, p. 8–46. (b) Schrock, R. R. High
Oxidation State Multiple Metal–Carbon Bonds. Chem. Rev. 2002,
102, 145–180. (c) Schrock, R. R. Recent Advances in High Oxidation
State Mo and W Imido Alkylidene Chemistry. Chem. Rev. 2009, 109,
3211–3226.
(7) (a) Wengrovius, J. H., Ph.D. Thesis, Massachusetts Institute of
Technology, Cambridge, Massachusetts, 1982, pages 283 and 290.
(b) Rocklage, S. M.; Schrock, R. R.; Churchill, M. R.; Wasserman, H.
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W(CCMe3)(PHPh)(PEt3)2Cl2. Organometallics 1982, 1, 1332–1338.
(8) Schrock, R. R.; Czekelius, C. C. Recent Advances in the Syntheses
and Applications of Molybdenum and Tungsten Alkylidene and
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Chemistry. Angew. Chem. Int. Ed. 2003, 42, 156–181. (b) Copéret, C.;
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Organometallic and Coordination Chemistry toward Single-Site
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Activities. Chem. Rev. 2016, 116, 323–421. (c) Solans-Monfort, X.;
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Species: How and Why Do They Differ in Structure, Activity, and
Efficiency in Alkene Metathesis? Organometallics 2012, 31, 6812–
6822.
(10) (a) Peryshkov, D. V.; Schrock, R. R.; Takase, M. K.; Müller,
P.; Hoveyda, A. H. Z-Selective Olefin Metathesis Reactions
Promoted by Tungsten Oxo Alkylidene Complexes. J. Am. Chem.
Soc. 2011, 133, 20754–20757. (b) Peryshkov, D. V.; Schrock, R. R.
Synthesis of Tungsten Oxo Alkylidene Complexes. Organometallics
2012, 31, 7278–7286. (c) Peryshkov, D. V.; Forrest, W. P., Jr.;
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Tungsten Complexes That Are Relevant to Olefin Metathesis.
Organometallics 2013, 32, 5256–5259.
metathesis-active
molybdenum
oxo
alkylidene
complexes will be observed or isolated under the right
circumstances, and look forward to comparing their
metathesis reactions with those catalyzed by tungsten
analogs.10,16
ASSOCIATED CONTENT
Supporting Information
Experimental details of the syntheses of all compounds,
NMR and spectral data, details of the metathesis
experiments, and X-ray crystallographic files. This
material is available free of charge via the Internet
at http://pubs.acs.org.
Accession Codes
CCDC 1865865−1865868 contain the supplementary
crystallographic data for this paper. These data can be
obtained free of charge via
www.ccdc.cam.ac.uk/data_request/cif, or by emailing
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.
AUTHOR INFORMATION
Corresponding Author
* rrs@mit.edu
ORCID
Feng Zhai: 0000-0001-7892-3188
Konstantin V. Bukhryakov: 0000-0002-8425-9671
Richard R. Schrock: 0000-0001-5827-3552
Amir H. Hoveyda: 0000-0002-1470-6456
(11) (a) Fairhurst, S. A.; Hughes, D. L.; Marjani, K.; Richards, R.
L. Insertion of Alkynes into Molybdenum–Phosphine and –Carbon
bonds. Crystal Structures of the Alkyne–Ylide Complex
[MoO(SC6H2Pri3-2,4,6)2{η2-CHC(tol)}{C(tol)CHPMePh2}] (tol =
C6H4Me-4) and the Phosphonium–Alkylidene complex
Notes
The authors declare no competing financial interests.
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