Multiple C-H Activations of Linear Alkanes by Various (??5-Cyclopentadienyl)W(NO)(CH2CMe3)2 Complexes

Article abstract of DOI:10.1021/acs.organomet.7b00034

As illustrated in the accompanying diagram, thermolysis of Cp?W(NO)(CH₂CMe₃)₂ (Cp? = n⁵-C₅Me₅) at 80 °C in neat linear alkanes effects three successive C-H bond activations of the hydrocarbon substrates and forms Cp?W(NO)(H)(n³-allyl) complexes in which the allyl ligands are derived from the alkanes. These allyl hydrido compounds exist in solutions as mixtures of isomers containing monosubstituted (i.e., terminal) or 1,3-disubstituted (i.e., internal) allyl ligands which can have either an endo or exo orientation with the substituent groups being either proximal or distal to the nitrosyl ligand. Due to steric factors the most abundant isomer in all cases has a monosubstituted allyl ligand in the endo orientation with the alkyl end distal to the nitrosyl ligand. In addition, the relative abundance of Cp?W(NO)(H)(n³-allyl) isomers having monosubstituted allyl ligands decreases with increasing length of the n-alkane chain. Further thermolysis of the Cp?W(NO)(H)(n³-allyl) complexes results in the liberation of alkenes. Whether initiated by Cp?W(NO)(CH₂CMe₃)₂ or independently synthesized Cp?W(NO)(H)(n³-allyl) complexes, the n-alkane dehydrogenations generally result in the preferential formation of 1-alkenes. They are stoichiometric, and their outcomes are not significantly affected by varying the experimental conditions employed (e.g., time, temperature, an open system, use of an H₂ acceptor, etc.) or by changing the initial bis(neopentyl) tungsten reactant to its Cp^Et (n⁵-C₅Me₄Et) and Cp^iPr (n⁵-C₅H₄ⁱPr) analogues or to Cp?Mo(NO)(CH₂CMe₃)₂. The results of DFT calculations are consistent with these dehydrogenations proceeding via 16e Cp?M(NO)(n²-alkene) (M = Mo, W) intermediates that are in equilibrium with their more stable 18e Cp?M(NO)(H)(n³-allyl) isomers. These intermediates facilitate the allyl ligand exchange reactions depicted in the accompanying diagram by functioning as internal hydrogen acceptors during the dehydrogenation of the linear alkanes. Thermolysis of the final hydrido allyl complexes liberates the desired alkenes.

Full text of DOI:10.1021/acs.organomet.7b00034

Article
pubs.acs.org/Organometallics
Multiple C−H Activations of Linear Alkanes by Various
(η5‑Cyclopentadienyl)W(NO)(CH2CMe3)2 Complexes
Monica V. Shree,† Diana Fabulyak,† Rhett A. Baillie,† Guillaume P. Lefevre,† Kevan Dettelbach,†
̀
Aurelien Bethegnies,† Brian O. Patrick,† Peter Legzdins,*,† and Devon C. Rosenfeld‡
́
́
†Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
‡The Dow Chemical Company, 2301 North Brazosport Boulevard, Freeport, Texas 77541, United States
S
* Supporting Information
ABSTRACT: As illustrated in the accompanying diagram,
thermolysis of Cp*W(NO)(CH2CMe3)2 (Cp* = η5-C5Me5) at
80 °C in neat linear alkanes effects three successive C−H bond
activations of the hydrocarbon substrates and forms Cp*W-
(NO)(H)(η3-allyl) complexes in which the allyl ligands are
derived from the alkanes. These allyl hydrido compounds exist
in solutions as mixtures of isomers containing monosubstituted (i.e., terminal) or 1,3-disubstituted (i.e., internal) allyl ligands
which can have either an endo or exo orientation with the substituent groups being either proximal or distal to the nitrosyl ligand.
Due to steric factors the most abundant isomer in all cases has a monosubstituted allyl ligand in the endo orientation with the
alkyl end distal to the nitrosyl ligand. In addition, the relative abundance of Cp*W(NO)(H)(η3-allyl) isomers having monosub-
stituted allyl ligands decreases with increasing length of the n-alkane chain. Further thermolysis of the Cp*W(NO)(H)(η3-allyl)
complexes results in the liberation of alkenes. Whether initiated by Cp*W(NO)(CH2CMe3)2 or independently synthesized
Cp*W(NO)(H)(η3-allyl) complexes, the n-alkane dehydrogenations generally result in the preferential formation of 1-alkenes.
They are stoichiometric, and their outcomes are not significantly affected by varying the experimental conditions employed
(e.g., time, temperature, an open system, use of an H2 acceptor, etc.) or by changing the initial bis(neopentyl) tungsten reactant
i
to its CpEt (η5-C5Me4Et) and CpiPr (η5-C5H4 Pr) analogues or to Cp*Mo(NO)(CH2CMe3)2. The results of DFT calculations are
consistent with these dehydrogenations proceeding via 16e Cp*M(NO)(η2-alkene) (M = Mo, W) intermediates that are in
equilibrium with their more stable 18e Cp*M(NO)(H)(η3-allyl) isomers. These intermediates facilitate the allyl ligand exchange
reactions depicted in the accompanying diagram by functioning as internal hydrogen acceptors during the dehydrogenation of
the linear alkanes. Thermolysis of the final hydrido allyl complexes liberates the desired alkenes.
substituents, R, are not coordinated to the metal centers in the
solid-state molecular structures of the product complexes, the
electron-deficient tungsten centers engaging instead in agostic
C−H interactions with the neopentyl ligands.1 Finally, thermo-
lysis of Cp*W(NO)(CH2CMe3)2 in neat ethylcyclohexane
affords Cp*W(NO)(H)(η3-C8H13), which is an exocyclic allyl
hydrido complex resulting from three successive C−H activa-
tions of the organic substrate (Scheme 1).
INTRODUCTION
■
In recent years we have been investigating the thermal chem-
istry of various (η5-cyclopentadienyl)M(NO)-containing com-
plexes of molybdenum and tungsten with a view to developing
these compounds as mediators for the efficient and selec-
tive conversion of hydrocarbon feedstocks into functionalized
organic compounds.1 The 16e Cp*M(NO)(CH2CMe3)2
(Cp* = η5-C5Me5) complexes are particularly important members
of this group of compounds.2 For instance, thermal activation
of Cp*W(NO)(CH2CMe3)2 at 70 °C in neat hydrocarbon
solutions generates the reactive neopentylidene complex
Cp*W(NO)(CHCMe3), which effects the activation of
solvent C−H bonds even in the presence of excess PMe3
(Scheme 1). Labeling studies utilizing benzene-d6 demonstrate
that the C−H activation does indeed occur via the neopen-
tylidene complex, since the deuterium label ends up on the
methylene carbon atom of the neopentyl ligand. In addition,
the neopentylidene intermediate has also been trapped and
isolated as its 18e PMe3 adduct (Scheme 1).
The selective dehydrogenation of alkanes to alkenes is of
great interest, since olefins are key factors in most processes in
the chemical industry.3 We have now extended our investiga-
tions of the characteristic chemistry of Cp*W(NO)(CH2CMe3)2
to its reactions with linear alkanes and related hydrocarbons,
and we have also included its CpEt (η5-C5Me4Et) and CpiPr
(η5-C5H4 Pr) analogues as well as Cp*Mo(NO)(CH2CMe3)2 at
i
times in these studies. In the process we have discovered that
by effecting initial multiple C−H bond activations of the
hydrocarbon substrates all of these complexes also mediate the
subsequent dehydrogenation of the hydrocarbons. In this article
we present the complete results of these investigations.
As shown in Scheme 1, Cp*W(NO)(CHCMe3) can also
be employed for the preferential activation of the more ste-
rically hindered ortho C−H bonds of substituted arenes,
C6H5R (R = OMe, Cl, CCPh). Interestingly, the arene
Received: January 13, 2017
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 1. Some C−H Activation Chemistry of the Cp*W(NO)(CHCMe3) Reactive Intermediate That Is Generated by
Thermolysis of Cp*W(NO)(CH2CMe3)2
1
ligands in the H NMR spectrum of the final reaction mixture.
The relative abundances of the isomers are manifestations of
steric factors, the most abundant isomer A having the allyl
ligand in an endo orientation and the methyl group distal to
the nitrosyl ligand. All four of these complexes have been
synthesized previously in similar ratios, but in much lower
isolated yields (49 vs 19%), by the sequential treatment of
Cp*W(NO)Cl2 in THF with 1 equiv of Mg(CH2CH
CHMe)2 followed by an excess of LiBH4.4 In addition, the
solid-state molecular structure of isomer A has also been
previously established.4
RESULTS AND DISCUSSION
■
Reactions of Cp*W(NO)(CH2CMe3)2 with Linear Alka-
nes. Propane. Thermolysis of Cp*W(NO)(CH2CMe3)2 at
100 °C in neat propane at 700 psig results in three successive
C−H activations of the alkane and formation of two isomers
of orange Cp*W(NO)(H)(η3-C3H5) which differ in the exo
(isomer A) and endo (isomer B) orientations of their allyl
ligands (Scheme 2).
Scheme 2. Multiple C−H Activations of Propane Effected by
Cp*W(NO)(CH2CMe3)2
n-Pentane, n-Hexane, n-Heptane, and n-Octane. The
reactions of Cp*W(NO)(CH2CMe3)2 with longer-chain
alkanes have all been performed in a similar manner. Deep
burgundy red solutions of the organometallic reactant in the
neat alkanes have been maintained at 80 °C for 17 h to produce
golden brown final reaction mixtures. The allyl hydride
products can be purified by column chromatography on silica
using a gradient of 0−20% EtOAc in hexanes, and they have
been isolated as yellow solids in good yields. The isomers of
Cp*W(NO)(H)(η3-C5H9) and Cp*W(NO)(H)(η3-C7H13)
resulting from the reactions with n-pentane and n-heptane,
respectively, have been previously synthesized by thermolysis
of Cp*W(NO)(H)(η3-CH2CHCMe2) in the corresponding
n-alkanes.5
Cp*W(NO)(H)(η3-C3H5) has been characterized in C6D6
1
solution by H and 13C NMR spectroscopy, which also reveals
that the compound is reasonably stable at room temperature
but slowly decomposes over time.
n-Butane. The similar reaction of Cp*W(NO)(CH2CMe3)2
with n-butane affords the four isomers of yellow, air-stable
Cp*W(NO)(H)(η3-CH2CHCHMe) shown in Scheme 3. The
four isomers differ by the attachments of their allyl ligands,
which can have either an endo or exo orientation with the
methyl groups being either proximal or distal to the nitrosyl
ligand. The relative amounts of the different isomers have been
determined by integration of the meso signals of the allyl
Thermolysis of Cp*W(NO)(CH2CMe3)2 in neat n-hexane
leads to formation of Cp*W(NO)(H)(η3-C6H11), which is
1
isolable in 44% yield as a dark yellow oil. The H NMR
spectrum of this complex in C6D6 displays typical hydride
signals with 183W satellites ranging from δ −0.77 to −1.67 ppm
(Figure 1) due to a number of isomers, three of which have
B
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 3. Multiple C−H Activations of n-Butane Effected by Cp*W(NO)(CH2CMe3)2
a W−H band at 1908 cm−1, both of which are typical for such
bonds.5,6
As shown in Figure 2, the major isomer of Cp*W(NO)-
(H)(η3-C6H11) exhibits the customary σ−π distortion of the
allyl ligand4 that results in the C(2)−C(3) bond located trans
to the nitrosyl ligand having more sp2 character in comparison
to the C(1)−C(2) bond. This feature is apparent in the 13C
APT NMR spectrum of the complex (Figure 2), in which
signals due to C(3) and C(2) are at δ 85.6 and 102.7 ppm,
respectively, while the C(1) signal is at δ 39.3 ppm and also
exhibits 183W satellites (1JCW = 30.2 Hz). This σ−π distortion
occurs to some extent in all the allyl complexes discussed in this
article, but they are generally drawn with symmetrical allyl
ligands for simplicity.
Just as with n-hexane, the neopentylidene intermediate
also effects multiple C−H activations of n-octane. In this case
there are significantly more isomers of the Cp*W(NO)(H)
(η3-C8H15) complex detectable in the final product mixture
(Figure 3). This fact is not surprising, since the longer carbon
chain allows for the formation of more isomers having
disubstituted allyl ligands. In general, the spectroscopic features
of this complex are similar to those exhibited by the previously
discussed allyl hydrido compounds (vide supra).
1
Figure 1. Expansion of the 400 MHz H NMR spectrum (from δ
−0.77 to −1.67 ppm) of Cp*W(NO)(H)(η3-C6H11) in C6D6
displaying the resonances due to the W−H protons of the different
isomers.
been spectroscopically characterized. Two isomers having
monosubstituted (i.e., terminal) allyl ligands constitute 67%
of the isolated product mixture, and they have been fully char-
acterized. Partially characterized 1,3-disubstituted (i.e., internal)
allyl isomers of the product comprise 27% of the mixture, while
the remaining isomers make up 6% of the product mixture.
The IR spectrum of Cp*W(NO)(H)(η3-C6H11) as a Nujol
mull displays a nitrosyl stretching absorption at 1590 cm−1 and
Isomer Distribution of the Various Cp*W(NO)(H)(η3-
1
allyl) Products. Monitoring by H NMR spectroscopy indi-
cates that the relative abundance of Cp*W(NO)(H)(η3-allyl)
isomers having monosubstituted (i.e., terminal) allyl ligands
decreases with increasing length of the n-alkane chain (Table 1).
Figure 2. Expansion of the 100 MHz 13C APT NMR spectrum (δ 38.0−103.5 ppm) of Cp*W(NO)(H)(η3-C6H11) in C6D6 showing the allyl ligand
of the major isomer signals.
C
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Reactions of CpEtW(NO)(CH2CMe3)2 and CpiPrW(NO)-
(CH2CMe3)2 with n-Pentane. The thermal behavior of the
CpEt and CpiPr analogues of Cp*W(NO)(CH2CMe3)2 in linear
alkanes closely resembles that of the related Cp* complex
(Scheme 4). For example, thermolysis of CpEtW(NO)-
(CH2CMe3)2 in n-pentane for 19 h at 80 °C produces four
coordination isomers of CpEtW(NO)(H)(η3-C5H9), three of
which have been characterized by 1H NMR and 13C APT NMR
spectroscopy. The major isomer is the terminal allyl complex
(isomer A) that constitutes 60% of the mixture, while the
internal allyl complex (isomer B) makes up 13% of the mixture
and the other minor isomer C makes up 13% of the mixture.
Similarly, thermolysis of an n-pentane solution of CpiPrW-
(NO)(CH2CMe3)2 for 2 days at 60 °C results in the produc-
tion of CpiPrW(NO)(H)(η3-C5H9), which can be isolated as
a dark yellow oil. In solution three isomers of this complex have
been identified by 1H and 13C NMR spectroscopy. Two of these
isomers contain a terminal allyl ligand (i.e., isomers A and C)
and constitute 55% of the isolated mixture, whereas the third
contains the internal allyl ligand (isomer B) and makes up 44%
of the isolated mixture.
Figure 3. Expansion of the 400 MHz 1H NMR spectrum (δ −1.76 to
−0.76 ppm) of Cp*W(NO)(H)(η3-C8H15) in C6D6 displaying the
resonances due to the W−H protons of the different isomers.
Table 1. Relative Abundances of Terminal- and Internal-
Allyl Complexes Formed by the Reactions of
Cp*W(NO)(CH2CMe3)2 with Various n-Alkanes
1
Alkene Formation. H NMR spectroscopic monitoring
of the reactions of Cp*W(NO)(CH2CMe3)2 with the various
n-alkanes summarized in Table 1 reveals that alkenes begin to
appear in the reaction mixtures after some of the Cp*W(NO)-
(H)(η3-allyl) products have been formed. These alkenes can be
isomer containing a
monosubstituted allyl 1,3-disubstituted allyl
ligand ligand
isomer containing a
1
isolated from the final mixtures by distillation, and their H
NMR spectra in C6D6 indicate that the ratio of terminal to
internal olefins is similar to that of their precursor allyl
complexes given in Table 1. Thus, as illustrated in Figure 4, the
1H NMR spectrum of octenes resulting from the reaction of
Cp*W(NO)(CH2CMe3)2 with n-octane indicates approxi-
mately equal amounts of terminal and internal isomers. This
fact mirrors the equal distribution of the mono- and disub-
stituted isomers of Cp*W(NO)(H)(η3-C8H15) in the final
product mixture (Table 1).
unassigned
allyl hydride
isomer rel
abundance
(%)
rel
rel
abundance
(%)
abundance
(%)
n-alkane
R
R′ + R″
n-pentane
n-hexane
n-heptane
n-octane
C2H5
C3H7
C4H9
C5H11
87
67
56
46
C2H6
C3H8
C4H10
C5H12
13
27
35
46
0
6
9
8
Alkene formation can also be initiated by the Cp*W(NO)-
(H)(η3-allyl) complexes, as illustrated by the sequential ther-
molyses reactions presented in Scheme 5. These conversions
can be effected in one vessel by removing the organic com-
pounds from each final reaction mixture in vacuo and then
introducing neat n-alkane as the solvent for the next step. The
organic and organometallic products formed after each step
have been identified by 1H NMR spectroscopy and low-
resolution EI mass spectrometry, and the final brown reaction
mixture has been purified by flash chromatography on silica
using a gradient of 0−20% EtOAc in hexanes as eluant to
obtain the mixture of isomers of Cp*W(NO)(H)(η3-C8H15) as
a dark yellow oil in overall 10% yield.
Thus, thermolysis of Cp*W(NO)(CH2CMe3)2 in n-pentane
yields predominantly the terminal allyl coordination isomers of
Cp*W(NO)(H)(η3-CH2CHCHCH2Me), while the analogous
reaction with n-octane affords approximately equal amounts of
Cp*W(NO)(H)(η3-C8H15) having mono- and disubstituted
allyl ligands.
Due to steric factors the most abundant isomer in all
cases has a monosubstituted allyl ligand in the endo orienta-
tion with the alkyl end distal to the nitrosyl ligand: 58% for
Cp*W(NO)(H)(η3-CH2CHCHMe), 63% for Cp*W(NO)
(H)(η3-CH2CHCHCH2Me), 52% for Cp*W(NO)(H)(η3-
CH2CHCH(CH2)2Me), 41% for Cp*W(NO)(H)(η3-CH2-
CHCH(CH2)3Me), and 35% for Cp*W(NO)(H)(η3-CH2-
CHCH(CH2)4Me).
Further insights about the dehydrogenation processes
initiated by Cp*W(NO)(H)(η3-allyl) complexes have been
Scheme 4. Multiple C−H Activations of n-Pentane Effected by CpEtW(NO)(CH2CMe3)2 and CpiPrW(NO)(CH2CMe3)2
D
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 2. Dehydrogenation Performance Data
ratio of dehydrogenation
products
complex
substrate
n-pentane
Cp*W(NO)(CH2CMe3)2
1-pentene:2-pentene
76:24
a
(dried)
n-pentane
(undried)
1-pentene:2-pentene
67:33
b
n-hexane
(undried)
1-hexene:internal isomers
65:35
n-octane
(undried)
1-octene:internal isomers
35:65
Cp*Mo(NO)(CH2CMe3)2
CpEtW(NO)(CH2CMe3)2
CpiPrW(NO)(CH2CMe3)2
n-pentane
1-pentene
1-hexene
1-octene
(undried)
n-hexane
(undried)
1
Figure 4. Expansion from δ 4.85 to 5.88 ppm of the 400 MHz H
NMR spectrum of the distilled organic products (in C6D6) isolated
after thermolysis of Cp*W(NO)(CH2CMe3)2 in n-octane.
n-octane
(undried)
n-pentane (dried) 1-pentene:2-pentene
72:28
obtained by monitoring the thermolysis of Cp*W(NO)(H)
(η3-CH2CHCMe2) in 98% D n-pentane-d12 for 18 h at 80 °C
by H NMR spectroscopy. In agreement with the transforma-
tions shown in Scheme 5, the spectral changes accompanying
this reaction are consistent with Cp*W(NO)(D)(η3-CD2CDCD-
CD2CD3) and DH2CCDHCHMe2 being the principal products
formed. Furthermore, the signal due to the organometallic
product diminishes upon additional heating, a feature consis-
tent with the expulsion of C5D10 from the tungsten’s coordina-
tion sphere.
n-pentane
(undried)
1-pentene:2-pentene
76:24
1
n-octane (dried)
1-octene:internal isomers
54:46
n-pentane
(undried)
1-pentene:2-pentene
70:30
CpEtW(NO)(H)(η3-
CH2CHCHEt)
n-pentane (dried) 1-pentene:2-pentene
47:53
n-octane (dried)
1-octene:internal isomers
51:49
Cp*W(NO)(H)(η3-
CH2CHCMe2)
n-pentane (dried) 1-pentene:2-pentene
70:30
Whether initiated by Cp*W(NO)(CH2CMe3)2 or a Cp*W-
(NO)(H)(η3-allyl) complex, the n-alkane dehydrogenations
generally result in the preferential formation of 1-alkenes. Repre-
sentative examples of these processes have been monitored by
1H NMR spectroscopy and are summarized in Table 2, and the
experiments performed to obtain these data are described in the
Supporting Information.
n-octane
1-octene:internal isomers
40:60
(undried)
CpEtW(NO)(H)(η3-
n-octane (dried)
1-octene:internal isomers
58:42
CH2CHCMe2)
a
The designation “dried” indicates that the n-alkane reactant contains
b
less than 0.0001 wt % of water. The designation “undried” indicates
that the n-alkane reactant contains from 0.0001 to 0.01 wt % of water.
Olefin Quantification and Effects of Various Factors
on Dehydrogenation Processes. We have also investigated
in some detail CpEtW(NO)(H)(η3-C5H9), CpEtW(NO)(H)-
(η3-CH2CHMe2), and CpEtW(NO)(CH2CMe3)2 as represen-
tative compounds to see if changing experimental conditions
affect their dehydrogenations of n-octane as a representative
alkane. During these investigations the 1-octene, trans-2-octene,
cis-2-octene, and trans-4-octene products were quantified by
GC/FID methods throughout with the use of dodecane as an
internal standard. All isomers of octene could not be quantified
because of the overlap of signals due to n-octane in the final
reaction mixtures. The results of these studies are summarized
in Table 3, and the experiments performed to obtain these
data are described in the Supporting Information. A variety of
factors are known to affect the dehydrogenation of hydro-
carbons by soluble transition-metal complexes.3 The specific
factors examined during the current study are summarized in
the following paragraphs.
Reflux Conditions. One method widely used to improve
dehydrogenation activity is to reflux the reaction mixture to
remove any H2 produced in situ that could hinder further
olefin formation.7 However, refluxing a solution of CpEtW-
(NO)(H)(η3-C5H9) in n-octane at 80 °C for 24 h results in the
production of the same amounts of olefins as when the mixture
is not refluxed (entries 1 and 8 in Table 3). Furthermore,
thermolysis in the presence of added H2 (100 psig) also results
in no change in the production of octenes (entry 7 in Table 3),
thereby indicating that H2 does not inhibit dehydrogenation
activity.
Use of a Hydrogen Acceptor. It has been previously
demonstrated that a sacrificial hydrogen acceptor such as tert-
butylethylene (TBE) can be used to improve the dehydrogen-
ation activity by participating in transfer dehydrogenation
processes.3 In addition, olefin formation can be inhibited by
high concentrations of the hydrogen acceptor. However, the
Scheme 5. Sequential Thermolysis Reactions Involving Cp*W(NO)(H)(η3-allyl) Complexes and Their Isomers at 80 °C
for 18 h
E
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
dehydrogenation processes being effected in a noncatalytic
manner without the evolution of dihydrogen.
Table 3. Quantification of Four Octene Isomers Formed by
Dehydrogenation of n-Octane
Theoretical Considerations. The reactivity of the Cp*M-
(NO)(CH2CMe3)2 complexes (M = Mo, W) with n-alkanes
has also been investigated from a theoretical point of view by
means of DFT calculations. As noted earlier, these complexes
(AMo and AW in Scheme 6) generate the 16e alkylidene inter-
mediate complexes BMo and BW, respectively, upon thermal
activation. BMo and BW then effect the terminal C−H activation
of linear alkanes (such as n-pentane) and form the bis(alkyl)
compounds DMo and DW, respectively, which are stabilized by
agostic interactions. The formation of both bis(alkyl) com-
plexes is energetically favored, with the formation of DMo from
BMo having an overall computed exothermicity of 72 kJ mol−1.
Similarly, the formation of DW from BW has a computed
exothermicity of 95 kJ mol−1.
As shown in Scheme 7, complexes DMo and DW can then
undergo β-hydride elimination leading to the formation of
neopentane and the unsaturated 16e η2-alkene intermediate
complexes EMo and EW, respectively. These conversions are
expected to proceed relatively quickly, since they have relatively
low computed activation barriers (i.e., 46 kJ mol−1 for TS1Mo
and 60 kJ mol−1 for TS1W).
time
octenes
yield
b
a
b
entry
1
complex
factor examined
standard
(h) (mmol)
(%)
CpEtW(NO)(H)
24
26
20
72
24
5
0.207
0.219
0.241
0.205
0.199
0.244
0.309
0.244
0.121
0.266
46
80
55
45
55
70
89
69
37
77
(η3-C5H9)
2
CpEtW(NO)(H)
change in allyl
(η3-CH2CHMe2)
3
CpEtW(NO)
(CH2CMe3)2
bis(neopentyl)
complex
4
CpEtW(NO)(H)
time
(η3-C5H9)
5
CpEtW(NO)(H)
decreased complex
concentration
(η3-C5H9)
6
CpEtW(NO)(H)
120 °C
(η3-C5H9)
7
CpEtW(NO)(H)
100 psig H2
reflux
24
24
24
24
(η3-C5H9)
8
CpEtW(NO)(H)
(η3-C5H9)
9
CpEtW(NO)(H)
2 equiv TBE
40 equiv TBE
(η3-C5H9)
10
CpEtW(NO)(H)
(η3-C5H9)
a
All thermolyses were performed at 80 °C unless indicated otherwise.
1-Octene, trans-2-octene, cis-2-octene, and trans-4-octene were
quantified by GC/FID methods. Results given are the average of
b
Once formed, the unsaturated η2-alkene complex E can
follow the three different reaction pathways presented in
Scheme 7. The first pathway (path A) involves the isomer-
ization of E into the corresponding 18e allyl hydride complex F.
The formation of F under thermal conditions occurs readily,
since the computed activation barrier is 23 kJ mol−1 for the
molybdenum system (TS2Mo, Scheme 8) and 15 kJ mol−1 for
the tungsten congener (TS2W). As depicted in Scheme 8, the
formation of the allyl hydride complexes F is very exothermic,
and so the reverse path to regenerate complexes E has a high
activation barrier (88 kJ mol−1starting from FMo and 107 kJ mol−1
starting from FW).
two or more runs for which reproducibility averaged 1%.
dehydrogenation of n-octane by CpEtW(NO)(H)(η3-C5H9) at
both low and high concentrations of TBE results in no
significant changes in reactivity (entries 9 and 10 in Table 3).
Decreased Complex Concentration. Decreasing the con-
centration of the transition-metal complex is known to improve
dehydrogenation activity presumably by reducing the proximity
of reactive intermediates to one another.8 During the current
study it has been found that diluting the concentration of
CpEtW(NO)(H)(η3-C5H9) to 0.1 mol % shows no significant
improvement in octene production (entry 5 in Table 3).
Different Allyl Ligand. CpEtW(NO)(H)(η3-CH2CHCMe2)
has been synthesized to explore the activity of an alternative
allyl ligand complex. As shown in entries 1 and 2 of Table 3, the
compound produces amounts of olefins comparable to those
produced by the CpEtW(NO)(H)(η3-C5H9) standard.
Temperature and Time. Maintaining a solution of n-octane
and CpEtW(NO)(H)(η3-C5H9) at 120 °C for 5 h (entry 6 in
Table 3) produces the same amount of olefin as that when the
mixture is heated at 80 °C for 24 h (entry 1 in Table 3). Also,
increasing the duration of reaction from 24 to 72 h (entries 1
and 4 in Table 3) results in no change in octene formation.
Even though the CpEtW(NO)(CH2CMe3)2 complex does
produce slightly greater amounts of 1-octene, trans-2-octene,
cis-2-octene, and trans-4-octene (entry 3 in Table 3), the data
presented in Table 3 indicate that none of the factors exam-
ined results in any significant increase in olefin production.
Furthermore, they are consistent with these homogeneous
The second pathway that can be followed by complex E
consists of a symmetric ligand-scrambling reaction (path B,
Scheme 7). This process involves the one-step C−H activation
of a second pentane molecule and subsequent addition of the
hydrogen atom to the η2-alkene ligand. These operations afford
the symmetric bis(pentyl) complexes G, which can undergo
stabilization by agostic interactions to give H. The formation
of complexes G is expected to be rather facile as well, since
they only require a computed barrier of 76 kJ mol−1 (TS3Mo
Scheme 9) or 59 kJ mol−1 (TS3W).
,
The final pathway that can formally be followed by com-
plexes E leads to terminal dehydrogenation of pentane,
affording 1-pentene (path C, Scheme 7). E can react with
pentane via a terminal C−H bond-activation process to
form the mixed alkyl hydride species Cp*M(NO)(H)(η1-
C5H11)(η2-CH2CHCH2CH2Me) (I) with a computed bar-
rier of 131 kJ mol−1 for the molybdenum precursor (TS4Mo
,
Scheme 10), and a slightly lower barrier for the tungsten
Scheme 6. Terminal C−H Activation of n-Pentane by Cp*M(NO)(CH2CMe3)2 (M = Mo, W)
F
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 7. Generation and Reactivity of Cp*M(NO)(η2-CH2CHCH2CH2Me) (M = Mo, W)
(141 kJ mol−1 for EMo and 117 kJ mol−1 for EW for the rate-
determining steps governed by TS5Mo and TS5W). Since the
evolution of H2 is not observed experimentally, these barriers
evidently prevent the dehydrogenations from being effected in
this manner by these complexes.
Scheme 8. Formation of Allyl Hydride Complexes F from E
(Path A)
Probable Mechanism for Alkane Dehydrogenations
Initiated by Cp*W(NO)(H)(η3-allyl) Complexes. The first
step in this mechanism is the isomerization of the 18e
Cp*W(NO)(H)(η3-allyl) complexes (such as F in Scheme 7)
to the 16e Cp*W(NO)(η2-alkene) intermediate species (such
as E in Scheme 7). Since H2 evolution has not been detected
during dehydrogenations of the various n-alkanes, path C with
its relatively high activation barriers (Scheme 10) is probably
not being followed by complexes E during these trans-
formations, and it is therefore indicated with dashed lines in
Scheme 7. In contrast, path B is much more energetically viable
for complexes E (Scheme 9) and can result in allyl ligand and
alkane exchange (as observed experimentally) with the initial
organometallic reactant functioning as an internal hydrogen
acceptor (Scheme 11).5 The alkenes are then released by
thermal decomposition of the final Cp*W(NO)(H)(η3-allyl)
products. For each of the transformations depicted in Scheme 5,
the C6D6 1H NMR spectra of the residues remaining after
removal of the volatiles and any undecomposed Cp*W(NO)-
(H)(η3-allyl) compounds from the final reaction mixtures dis-
play a plethora of signals, but none that can be attributed to the
existence of W−H linkages. Their mass spectra (LREI, m/z,
probe temperature 200 °C) exhibit clusters of signals centered
at 598 and 730 whose isotopic patterns indicate that the final
analogue (113 kJ mol−1, TS4W). Complex I can then liberate
1-pentene and form complex J in a globally exothermic pathway
(computed exothermicity: 65 kJ mol−1 for JMo and 33 kJ mol−1
for JW). Complex J can then intramolecularly dehydrogenate
the lateral alkyl chain and convert to complex L (computed
barrier: 104 kJ mol−1 for TS5Mo and 112 kJ mol−1 for TS5W).
In the final step L regenerates complex E and releases H2
to complete the dehydrogenation process. Interestingly, the
decoordination of the η2-H2 ligand is exothermic for LMo
(exothermicity of 13 kJ mol−1) and slightly endothermic for
LW (3 kJ mol−1). However, relatively large energy barriers
must be surmounted during this dehydrogenation pathway
G
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 9. Symmetric Ligand-Scrambling Reactions of Complexes E (Path B)
Scheme 10. Terminal Dehydrogenation of n-Pentane to 1-Pentene Mediated by Complexes E (Path C)
reactions are mechanistically distinct from the dehydrogen-
ations of linear alkanes described in this article, since they
do not produce detectable amounts of any Cp*W(NO)(H)
(η3-allyl) complexes. The experimental details of these conver-
sions are outlined in the Supporting Information.
Scheme 11. Allyl-ligand and Alkane Exchange Reactions of
Cp*W(NO)(H)(η3-allyl) Complexes
CONCLUSION
■
This study has demonstrated that upon thermolysis various
(η5-cyclopentadienyl)W(NO)(CH2CMe3)2 complexes react
with linear alkanes by effecting three adjacent C−H bond
activations of the organic substrates while forming (η5-cyclo-
pentadienyl)W(NO)(H)(η3-allyl) compounds in which the
allyl ligands are derived from the alkanes. Upon further
thermolysis the (η5-cyclopentadienyl)W(NO)(H)(η3-allyl)
complexes eliminate terminal and internal alkenes from
the metals’ coordination spheres in a ratio similar to that
extant in their organometallic precursors. The overall n-alkane
decomposition products of these transformations are bi- and/or
trimetallic tungsten species. The exact natures of these com-
pounds remain to be ascertained.
Related Dehydrogenations of Ethylbenzene and
n-Propylbenzene. Thermolysis of Cp*W(NO)(CH2CMe3)2
in ethylbenzene and n-propylbenzene results in the production
of some styrene and trans-β-methylstyrene, respectively. These
H
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Characterization Data for the Endo Isomer of Cp*W(NO)(H)(η3-
C3H5) (79%).
dehydrogenations are stoichiometric, and their outcomes are
not significantly affected by varying the experimental conditions
employed (e.g., time, temperature, an open system, employing
an H2 acceptor, etc.). The search for other molecular scaffolds
that can effect these dehydrogenations in a catalytic manner
continues.
IR (cm−1): 1600 (s, νNO). MS (LREI, m/z, probe temperature
150 °C): 391 [M+, 184W]. HRMS-EI (m/z): [M+, 186W] calcd for
EXPERIMENTAL SECTION
■
1
C13H21NO186W 393.11669, found 393.11676. H NMR (600 MHz,
General Methods. All reactions and subsequent manipulations
involving organometallic reagents were performed under anhydrous
and anaerobic conditions except where noted. All inert gases were
purified by passing them through a column containing MnO and then
through a column of activated 4 Å molecular sieves. Vacuum and inert-
atmosphere techniques were performed either using double-manifold
Schlenk lines or in Innovative Technologies LabMaster 100 and
MS-130 BG dual-station gloveboxes equipped with freezers main-
tained at −30 °C. Tetrahydrofuran (THF) and diethyl ether (Et2O)
were dried over sodium/benzophenone ketyl and freshly distilled prior
to use; pentane was dried over calcium hydride and freshly distilled
prior to use; solvents such as hexanes and ethyl acetate (EtOAc) were
not dried prior to use; all other solvents were dried according to
standard procedures.9 All binary magnesium reagents used were
prepared from the corresponding Grignard reagents.2 Cp*W(NO)-
(CH2CMe3)2,10 Cp*Mo(NO)(CH2CMe3)2,10 and CpiPrW(NO)-
C6D6): δ −1.28 (s, 1JHW = 118.8, 1H, WH), 0.32 (d, 3JHH = 11.0, 1H,
3
2
allyl CH2), 0.80 (dd, JHH = 13.9, JHH = 1.1, 1H, allyl CH2), 1.73 (s,
15H C5Me5), 3.01 (m, 1H, allyl CH2), 4.17 (m, 1H, allyl CH2), 4.51
(dddd, 3JHH = 18.0, 3JHH = 13.9, 3JHH = 11.0, 3JHH = 7.0, 1H, allyl CH).
13C NMR (150 MHz, C6D6): δ 11.0 (C5Me5), 44.6 (allyl CH2), 55.8
(allyl CH2), 102.4 (allyl CH), 105.0 (C5Me5). Sel NOE (600 MHz,
C6D6): δ irrad at −1.28, NOE at 4.17.
Partial Characterization Data for the Exo Isomer of Cp*W(NO)-
(H)(η3-C3H5) (21%).
11
1H NMR (600 MHz, C6D63): δ −0.99 (s, 1JHW = 124.0, 1H, WH), 1.67
(s, 15H C5Me5), 2.45 (d, JHH = 14.7, 1H, allyl CH2), 2.52 (m, 1H,
(CH2CMe3)2 were prepared according to the published procedures.
Pentamethylcyclopentadiene was obtained from Boulder Scientific Co.
All other chemicals and reagents were ordered from commercial
suppliers and used as received.
3
allyl CH2), 2.55 (d, JHH = 13.5, 1H, allyl CH2), 2.68 (m, 1H, allyl
CH), 3.64 (m, 1H, allyl CH2).
Unless otherwise specified, all IR samples were prepared as Nujol
mulls sandwiched between NaCl plates, and their spectra were
recorded on a Thermo Nicolet Model 4700 FT-IR spectrometer.
Except where noted, all NMR spectra were recorded at room
temperature on Bruker AV-300, AV-400 (direct and indirect probes),
and AV-600 instruments; all chemical shifts are reported in ppm, and
Reaction of Cp*W(NO)(CH2CMe3)2 with n-Butane. In a
glovebox, a Parr 5500 pressure reactor was charged with Cp*W-
(NO)(CH2CMe3)2 (1.092 g, 2.222 mmol). The reactor was sealed and
removed from the glovebox and purged six times with n-butane. Then
the reactor was placed in a dry ice/acetone bath (−78 °C) and its
contents were cooled to −1 °C. Butane gas was condensed into the
pressure reactor by opening the reactor to the butane gas cylinder for
1 min. Afterward the reaction mixture was warmed to room tem-
perature. The contents of the reactor were then stirred and heated to
100 °C, at which temperature the pressure of n-butane was 250 psig.
After 2.5 h the contents of the pressure reactor were cooled to room
temperature, and the gas was slowly vented. A dark brown solid
residue was obtained and purified by flash chromatography on silica.
A yellow band was eluted with a gradient of 0−20% EtOAc in hexanes,
affording a golden yellow eluate. Solvent was removed from the
eluate in vacuo to give Cp*W(NO)(H)(η3-C4H7) as a dark yellow oil
(0.440 g, 1.09 mmol, 49% yield). In solution four isomers of this
complex have been identified.
1
coupling constants are reported in Hz. H NMR spectra were refer-
enced to the residual protio isotopomer present in C6D6 (7.16 ppm).
13C NMR spectra were referenced to C6D6 (128.39 ppm). For
the characterization of most complexes two-dimensional NMR
experiments, {1H−1H} COSY, {1H−13C} HSQC, and {1H−13C}
HMBC, were performed to correlate and assign 1H and 13C
1
NMR signals and establish atom connectivity; H NOE NMR was
used for determination of solution structures. GC analyses (FID
detection) were performed on an Agilent 7890A GC instrument
equipped with a HP-5 ms (30 m × 0.25 mm × 0.25 μm) capillary
column. Low- and high-resolution mass spectra (EI, 70 eV) were
recorded by Mr. Marshall Lapawa of the UBC mass spec-
trometry facility using a Kratos MS-50 spectrometer, and elemental
analyses were performed by Mr. Derek Smith of the UBC
microanalytical facility. X-ray crystallographic data collection, solution,
and refinement were performed at the UBC X-ray crystallography
facility.
Characterization Data for Cp*W(NO)(H)(η3-C4H7).
Reaction of Cp*W(NO)(CH2CMe3)2 with Propane. A Parr
5500 reactor was charged with Cp*W(NO)(CH2CMe3)2 (0.146 g,
0.297 mmol). After the reactor was purged with gaseous C3H8
(six times), the reactor was placed in a dry ice/acetone bath
(−78 °C) and C3H8 was condensed into the reactor for 1 min. For
safety precautions the reactor was maintained at 1200 psig by releasing
pressure when necessary as the temperature was increased. The reactor
was removed from the bath, and its contents were stirred and heated
to 100 °C, at which temperature the C3H8 pressure was 700 psig. After
2 h 40 min the reactor was cooled by placing it in a water bath, and the
gas was vented. A brown solid residue was obtained and purified by
flash chromatography on silica. A yellow band was eluted with a
gradient of 30−50% Et2O in pentane, affording a yellow eluate.
Removal of solvent from the eluate afforded Cp*W(NO)(H)
(η3-C3H5) as a yellow solid. Two isomers of the complex, a and b,
IR (cm−1): 1597 (s, νNO). MS (LREI, m/z, probe temperature 150 °C):
405 [M+, 184W]. HRMS-EI (m/z): [M+, 186W] calcd for C14H23NO186
W
407.13234, found 407.13219. Anal. Calcd for C14H23NOW: C, 41.50;
H, 5.72; N, 3.46. Found: C, 42.26; H, 5.70; N, 3.24.
Complete characterization data for all four isomers have recently
been reported.4
Reaction of Cp*W(NO)(CH2CMe3)2 with n-Pentane. In a
glovebox a reaction flask was charged with Cp*W(NO)(CH2CMe3)2
(0.172 g, 0.350 mmol) and dried n-pentane (ca. 20 mL), affording a
burgundy red reaction mixture. The flask was sealed with a Kontes
greaseless stopcock, and then its contents were heated for 17 h at
80 °C to produce a brown mixture. After removal of the solvent in
vacuo, a dark brown solid residue was obtained and purified by flash
chromatography on silica. A yellow band was eluted with a gradient of
1
were identified in solution by H NMR spectroscopy in a 79:21 ratio,
respectively.
I
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
0−20% EtOAc in hexanes, affording a golden yellow eluate. Solvent
was removed from the eluate in vacuo to give Cp*W(NO)(H)
(η3-C5H9) as a dark yellow oil (0.074 g, 0.177 mmol, 50% yield).
In solution four isomers of this complex have been identified.
Characterization Data for Cp*W(NO)(H)(η3-C5H9).
Reaction of Cp*W(NO)(CH2CMe3)2 with n-Heptane. This
reaction was performed by employing the same procedure as used in
the reaction of Cp*W(NO)(CH2CMe3)2 with n-pentane. A reaction flask
was charged with Cp*W(NO)(CH2CMe3)2 (0.142 g, 0.289 mmol) and
n-heptane (ca. 20 mL), and then the solution was maintained at 80 °C for
17 h. Following the same purification method, Cp*W(NO)(H)(η3-
C7H13) was isolated as a dark yellow oil (0.075 g, 0.168 mmol, 58%
yield). In solution six isomers of this complex have been identified.
Characterization Data for Cp*W(NO)(H)(η3-C7H13).
IR (cm−1): 1596 (s, νNO). MS (LREI, m/z, probe temperature
150 °C): 419 [M+, 184W]. Anal. Calcd for C15H25NOW: C, 42.98;
H, 6.01; N, 3.34. Found: C, 42.94; H, 6.03; N, 2.95. In solution four
1
isomers of this complex have been identified by Sel H NOE NMR
spectroscopy. Complete characterization data for all four isomers have
IR (cm−1): 1592 (s, νNO), 1911 (w, νWH). MS (LREI, m/z, probe
temperature 150 °C): 447 [M+, 184W]. HRMS-EI (m/z): [M+, 186W]
calcd for C17H29NO186W 449.17929, found 449.17925. Anal. Calcd for
C17H29NOW: C, 45.65; H, 6.54; N, 3.13. Found: C, 45.38; H, 6.47;
N, 3.04. Complete spectroscopic characterization data for four isomers
of this complex have recently been reported.4
Reaction of Cp*W(NO)(CH2CMe3)2 with n-Octane. In a
glovebox a reaction flask was charged with Cp*W(NO)(CH2CMe3)2
(0.185 g, 0.377 mmol) and n-octane (ca. 20 mL), affording a burgundy
red reaction mixture. Thermolysis of this reaction mixture for 17 h at
80 °C produced a brown mixture that was worked up in the manner
described in the preceding paragraphs to give Cp*W(NO)(H)
(η3-C8H15) as a dark yellow oil (0.090 g, 0.195 mmol, 52% yield).
Characterization Data for Cp*W(NO)(H)(η3-C8H15) Containing
an Endo Monosubstituted Allyl Ligand (35%).
recently been reported.5
Reaction of Cp*W(NO)(CH2CMe3)2 with n-Hexane. This
reaction was performed by employing the same procedure as used
in the reaction of Cp*W(NO)(CH2CMe3)2 with n-pentane. A reac-
tion flask was charged with Cp*W(NO)(CH2CMe3)2 (0.197 g,
0.401 mmol) and n-hexane (ca. 20 mL), and then the solution was
maintained at 80 °C for 17 h. Following the same purification method,
Cp*W(NO)(H)(η3-C6H11) was isolated as a dark yellow oil (0.077 g,
0.178 mmol, 44% yield). In solution five isomers of this complex have
been identified, and three of these isomers have been characterized.
Characterization Data for Cp*W(NO)(H)(η3-C6H11) Containing
an Endo Monosubstituted Allyl Ligand (52%).
IR (cm−1): 1590 (s, νNO), 1908 (w, νWH). MS (LREI, m/z, probe
temperature 150 °C): 433 [M+, 184W]. HRMS-EI (m/z): [M+, 186W]
calcd for C16H27NO186W 435.16364, found 435.16361. 1H NMR
IR (cm−1): 1596 (s, νNO). MS (LREI, m/z, probe temperature 150 °C):
461 [M+, 184W]. HRMS-EI (m/z): [M+, 186W] calcd for C18H31NO186
W
(400 MHz, C6D6): δ −1.32 (s, 1JHW = 120.8, 1H, WH), 0.19 (d, 3JHH
=
463.19494, found 463.19534. 1H NMR (400 MHz, C6D6): δ −1.29 (s,
3
10.2, 1H, allyl C1H2), 0.90 (t, JHH = 7.4, 3H, allyl C6H3), 1.37−1.46
(m, 1H, allyl C5H2), 1.54−1.61 (m, 1H, allyl C5H2), 1.76 (s, 15H,
C5Me5), 1.84−1.90 (m, 1H, allyl C3H), 2.39 (m, 2H, allyl C4H2), 2.80
3
1JHW = 120.9, 1H, WH), 0.21 (d, JHH = 10.2, 1H, allyl C1H2), 0.91
(m, 3H, allyl C8H3), 1.77 (s, 15H, C5Me5), 1.25−1.33 (m, 2H, allyl
C6H2), 1.25−1.33 (m, 2H, allyl C7H2), 1.41−1.50 (m, 1H, allyl
C5H2), 1.55−1.65 (m, 1H, allyl C5H2), 1.90 (m, 1H, allyl C3H), 2.44
(m, 2H, allyl C4H2), 2.83 (dt, 3JHH = 7.0, 2JHH = 2.5, 1H, allyl C1H2),
3
2
3
(dt, JHH = 7.0, JHH = 2.8, 1H, allyl C1H2), 4.59 (ddd, JHH = 13.1,
3JHH = 10.2, 3JHH = 7.0, 1H, allyl C2H). 13C NMR (100 MHz, C6D6):
3
3
3
4.63 (ddd, JHH = 13.1, JHH = 10.0, JHH = 7.0, 1H, allyl C2H). 13C
NMR (100 MHz, C6D6): δ 11.0 (C5Me5), 14.7 (allyl C8H3), 23.4 (allyl
C7H2), 32.2 (allyl C6H2), 33.8 (allyl C5H2), 35.6 (allyl C4H2), 39.3
(allyl C1H2), 85.9 (allyl C3H), 102.6 (allyl C2H), 104.9 (C5Me5).
Anal. Calcd for C18H31NOW: C, 46.87; H, 6.77; N, 3.04. Found: C,
47.24; H, 6.89; N, 3.12.
δ 11.03 (C5Me5), 14.3 (allyl C6H3), 27.1 (allyl C5H2), 37.7 (allyl
C4H2), 39.3 (1JCW = 30.2, allyl C1H2), 85.6 (allyl C3H), 102.7 (allyl
C2H), 104.9 (C5Me5). Anal. Calcd for C16H27NOW: C, 44.36;
H, 6.28; N, 3.23. Found: C, 45.08; H, 6.30; N, 3.25.
Characterization Data for Cp*W(NO)(H)(η3-C6H11) Containing
an Endo 1,3-Disubstituted Allyl Ligand (16%).
Partial Characterization Data for Cp*W(NO)(H)(η3-C8H15) Con-
taining an Endo 1,3-Disubstituted Allyl Ligand (25%). 1H NMR
1
(400 MHz, C6D6): δ −1.44 (s, JHW = 121.2, 1H, WH), 0.93 (m, 3H,
allyl CH3), 1.76 (s, 15H, C5Me5), 4.44 (dd, 3JHH = 12.5, 3JHH = 9.4, 1H,
allyl CH). 13C NMR (100 MHz, C6D6): δ 10.8 (C5Me5), 14.4 (allyl
Me), 104.5 (allyl CH), 104.7 (C5Me5).
1
1H NMR (400 MHz, C6D6): δ −1.50 (s, JHW = 122.4, 1H, WH),
Partial Characterization Data for Cp*W(NO)(H)(η3-C8H15) Con-
taining an Endo 1,3-Disubstituted Allyl Ligand (21%).1H NMR (400
MHz, C6D6): δ −1.40 (s, 1JHW = 122.8, 1H, WH), 1.74 (s, 15H, C5Me5),
4.45 (m, 1H, allyl CH). 13C NMR (100 MHz, C6D6): δ 104.5 (allyl CH).
Partial Characterization Data for Another Cp*W(NO)(H)(η3-C8H15)
Isomer Containing an Endo Monosubstituted Allyl Ligand (11%).
0.76−0.84 (m, 1H, allyl CH), 1.12 (t, 3JHH = 7.3, 3H, allyl CH3), 1.59−
1.63 (m, 1H, allyl CH), 1.75 (s, 15H, C5Me5), 2.02 (d, 3JHH = 5.9, 3H,
allyl CH3), 2.37−2.45 (m, 1H, allyl CH2), 2.48−2.59 (m, 1H, allyl
3
3
CH2), 4.42 (dd, JHH = 12.7, JHH = 9.4, 1H, allyl C2H). 13C NMR
(100 MHz, C6D6): δ 10.8 (C5Me5), 18.0 (allyl CH3), 18.9 (allyl CH3),
28.5 (allyl CH2), 53.0 (allyl CH), 84.0 (allyl CH), 104.8 (C5Me5),
105.3 (allyl CH).
Partial Characterization Data for Cp*W(NO)(H)(η3-C6H11) Con-
taining an Endo Monosubstituted Allyl Ligand (15%). 1H NMR
(400 MHz, C6D6): δ −1.35 (s, 1JHW = 120.8, 1H, WH), 0.63 (d, 3JHH
=
3
13.5, 1H, allyl CH2), 1.75 (s, 15H, C5Me5), 4.11 (d, JHH = 7.4,
3
3
3
1H NMR (400 MHz, C6D6): δ −1.32 (s, 1JHW = 122.0, 1H, WH), 1.65
1H, allyl CH2), 4.32 (ddd, JHH = 13.5, JHH = 10.2, JHH = 7.4, 1H,
allyl CH). 13C NMR (100 MHz, C6D6): δ 52.4 (allyl CH2),
104.2 (allyl CH).
3
3
3
(s, 15H, C5Me5), 4.36 (ddd, JHH = 17.2, JHH = 9.8, JHH = 7.0, 1H,
allyl CH). 13C NMR (100 MHz, C6D6): δ 104.1 (allyl CH).
J
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Sequential Thermolyses of Allyl Hydride Complexes in
Various Saturated Hydrocarbons.
remove the magnesium salts, and the solvent was removed from the
filtrate in vacuo to obtain an oily residue. The residue was redissolved
in a minimum amount of pentane, and the solution was transferred to
the top of an alumina column (3.5 × 0.5 cm) made up in pentane.
A maroon band was eluted from the column with 4/1 pentane/Et2O.
Solvent removal from the eluate under reduced pressure afforded
X-ray-quality crystals of CpEtW(NO)(CH2CMe3)2 as maroon needles
(3.480 g, 6.886 mmol, 56% yield).
Characterization Data for CpEtW(NO)(CH2CMe3)2. IR (cm−1):
1579 (s, νNO). MS (LREI, m/z, probe temperature 150 °C): 505 [M+,
1
2
184W]. H NMR (400 MHz, C6D6): δ −1.42 (d, JHH = 12.9, 2H,
3
CH2CMe3), 0.79 (t, JHH = 7.8, 3H, C5Me4(CH2Me)), 1.39 (s, 18H,
CH2CMe3), 1.52 (s, 6H, C5Me4(CH2Me)), 1.60 (s, 6H,
3
C5Me4(CH2Me)), 2.00 (q, JHH = 7.8, 2H, C5Me4(CH2Me)), 2.78
(d, 2JHH = 12.9, 2H, CH2CMe3). 13C NMR (100 MHz, C6D6): δ 10.0
(C5Me4(CH2Me)), 10.1 (C5Me4(CH2Me)), 14.8 (C5Me4(CH2Me)),
19.1 (C5Me4(CH2Me)), 34.9 (CH2CMe3), 39.4 (CH2CMe3), 95.5
(CH2CMe3), 109.6 (C5Me4(CH2Me)), 110.4 (C5Me4(CH2Me)),
114.9 (C5Me4(CH2Me)). Anal. Calcd for C21H39NOW: C, 49.91;
H, 7.78; N, 2.77. Found: C, 49.67; H, 7.64; N, 3.12.
A reaction flask was charged with Cp*W(NO)(H)(η3-C4H7) (0.215 g,
0.531 mmol) and degassed n-pentane (ca. 25 mL) to produce a yellow
reaction mixture. The flask was sealed with a Kontes greaseless
stopcock, and then its stirred contents were maintained at 80 °C for
The solid-state molecular structure of CpEtW(NO)(CH2CMe3)2 is
shown in Figure S6 in the Supporting Information.
1
17 h to give a brown mixture. The H NMR spectra of the final
reaction mixture and the dark brown residue remaining after solvent
removal were recorded in C6D6. n-Hexane (ca. 25 mL) was next added
to the residue in the reaction vessel, and its stirred contents were
heated at 80 °C for 18 h. The 1H NMR spectra of the in situ and crude
reaction mixtures were again recorded. The same procedure was
repeated with n-heptane and then n-octane. The final brown reaction
mixture was purified by flash chromatography on silica. A yellow band
was eluted with a gradient of 0−20% EtOAc in hexanes to give a
golden yellow eluate. Solvent was removed from the eluate in vacuo
to give Cp*W(NO)(H)(η3-C8H15) as a dark yellow oil (0.025 g,
0.054 mmol, 10% yield). EI-MS spectra of the unpurified product
mixtures were also obtained after each step to confirm the presence of
the expected Cp*W(NO)(H)(η3-allyl) complexes.
Reaction of CpEtW(NO)(CH2CMe3)2 with n-Pentane. In a
glovebox, a thick-walled reaction flask with a Kontes stopcock was
charged with CpEtW(NO)(CH2CMe3)2 (1.828 g, 3.617 mmol),
n-pentane (ca. 195 mL), and a magnetic stir bar. On a Schlenk line
the stirred reaction mixture was heated at 80 °C overnight for 19 h.
Solvent was removed from the final yellow-brown solution in vacuo to
give a brown oil. Purification of this oil was performed by column
chromatography using silica support. A yellow band was eluted with
15−20% EtOAc in hexanes. Solvent was removed from the eluate
under reduced pressure to isolate CpEtW(NO)(H)(η3-C5H9) as a dark
yellow oil (0.695 g, 1.60 mmol, 44% yield). In solution, four coordina-
1
tion isomers of this complex were identified by H and 13C NMR
spectroscopy. The distribution of isomers was based on the related
data for the analogous Cp*W(NO)(H)(η3-C5H9) complex.5
Characterization Data for CpEtW(NO)(H)(η3-C5H9) Containing an
Endo Monosubstituted Allyl Ligand (60%).
Thermolysis of Cp*W(NO)(H)(η3-CH2CHCMe2) in n-Pentane-
d12. In a glovebox a J. Young NMR tube was charged with
Cp*W(NO)(H)(η3-CH2CHCMe2) (0.004 g) and 98%-D n-pentane-
d12 (ca. 1 mL) to produce a yellow mixture. The tube was sealed, and
the contents were heated at 80 °C while the progress of the reaction
1
was monitored by H NMR spectroscopy. After 2 days the reaction
mixture consisted of a dark orange solution with a small amount of a
black precipitate. The 1H NMR spectrum of this mixture revealed that
the initial organometallic reactant had been completely consumed, and
it exhibited a new signal at δ 2.06 ppm (referenced to the (CH3)2
signal of n-C5H12 at δ 0.9 ppm) that can be attributed to the Cp*
ligand of Cp*W(NO)(D)(η3-CD2CDCDCD2CD3). In addition, new
signals appeared in the alkane region expected for DH2CCDHCHMe2,
but their exact assignment was precluded by the presence of signals
in the same region due to the incompletely deuterated n-pentane
molecules in the solvent. Further heating of the mixture at 80 °C
simply resulted in a diminution of the Cp* signal.
IR (cm−1): 1576 (s, νNO). MS (LREI, m/z, probe temperature
1
150 °C): 433 [M+, 184W]. H NMR (400 MHz, C6D6): δ −1.42 (s,
3
1JHW = 117.0, 1H, WH), 0.17 (d, JHH = 10.1, 1H, C1H2), 0.85 (t,
3JHH = 7.6, 3H, C5Me4(CH2Me)), 1.11 (t, 3JHH = 7.2, 3H, C5H3), 1.73
(s, 3H, (C5Me4(CH2Me)), 1.76 (s, 3H, (C5Me4(CH2Me)), 1.77 (s,
3H, (C5Me4(CH2Me)), 1.81 (s, 3H, (C5Me4(CH2Me)), 1.84 (obs, 1H,
C3H), 2.18 (obs, 2H, C5Me4(CH2Me)), 2.49 (obs, 2H, allyl
Preparation of CpEtW(NO)(CH2CMe3)2. In a glovebox, a reaction
flask was charged with CpEtW(NO)Cl2 (5.320 g, 12.30 mmol, prepared
as described in the Supporting Information), Et2O (ca. 100 mL), and a
magnetic stir bar. A second flask was charged with (CH2CMe3)2Mg·
x(dioxane) (1.722 g, 12.30 mmol, 140 g/mol titer), Et2O (ca. 35 mL),
and a magnetic stir bar. Both flasks were removed from the glovebox
and attached to a Schlenk line, and their stirred contents were cooled to
−78 °C using a dry ice/acetone bath. The solution in the second flask
was then cannulated into the first flask dropwise over 30 min. The cold
bath was removed, and the stirred reaction mixture was warmed to
room temperature for 1 h, whereupon it became dark purple. A third
reaction flask was charged with (CH2CMe3)2Mg·x(dioxane) (2.082 g,
12.24 mmol, 170 g/mol titer), Et2O (ca. 35 mL),and a magnetic stir bar
and was cooled to −78 °C. The mixture in the first flask was again
cooled to −78 °C and was transferred dropwise via cannula over 30 min
into the third flask. The cold bath was then removed, and the final
reaction mixture was stirred for 30 min, whereupon it became dark
maroon. The mixture was then filtered through Celite on a porous frit to
3
3
C4H2), 2.84 (d, JHH = 7.5, 1H, C1H2), 4.58 (ddd, JHH = 12.9,
3JHH = 10.1, 3JHH = 7.5, 1H, C2H). 13C NMR (100 MHz, C6D6): δ 10.7
(C5Me4(CH2Me)), 10.7 (C5Me4(CH2Me)), 10.9 (C5Me4(CH2Me)),
11.0 (C5Me4(CH2Me)), 15.0 (C5Me4(CH2Me)), 17.7 (C5H3), 19.7
(C5Me4(CH2Me)), 28.2 (C4H2), 38.9 (C1H2), 87.7 (C3H), 101.7
(C2H), 104.3 (C5Me4(CH2Me)), 105.2 (C5Me4(CH2Me)), 110.4
(C5Me4(CH2Me)). Anal. Calcd for C16H27NOW: C, 44.36; H, 6.28;
N, 3.23. Found: C, 44.16; H, 6.31; N, 3.49.
Characterization Data for CpEtW(NO)(H)(η3-C5H9) Containing an
Endo 1,3-Disubstituted Allyl Ligand (13%).
1H NMR (400 MHz, C6D6): δ −1.42 (s, 1JHW = 117.0, 1H, WH), 0.85
3
(t, JHH = 7.6, 3H, C5Me4(CH2Me)), 1.66 (obs, 1H, allyl CH), 1.66
K
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(obs, 1H, allyl CH), 1.72 (s, 3H, C5Me4(CH2Me)), 1.74 (s, 3H,
C5Me4(CH2Me)), 1.75 (s, 3H, C5Me4(CH2Me)), 1.79 (s, 3H,
Characterization Data for CpiPrW(NO)(H)(η3-C5H9) Containing an
Endo 1,3-Disubstituted Allyl Ligand (44%).
3
C5Me4(CH2Me)), 2.18 (obs, 2H, C5Me4(CH2Me)), 2.31 (d, JHH
=
=
3
3
5.7, 3H, allyl Me), 2.32 (d, JHH = 5.7, 3H, allyl Me), 4.44 (dd, JHH
12.5, JHH = 9.4, 1H, allyl CH). 13C NMR (100 MHz, C6D6): δ 10.4
(C5Me4(CH2Me)), 10.4 (C5Me4(CH2Me)), 10.6 (C5Me4(CH2Me)),
10.7 (C5Me4(CH2Me)), 15.0 (C5Me4(CH2Me)), 18.9 (allyl Me), 19.7
(C5Me4(CH2Me)), 74.3 (allyl CH), 104.3 (C5Me4(CH2Me)), 105.2
(C5Me4(CH2Me)), 107.9 (allyl CH), 110.4 (C5Me4(CH2Me)).
Characterization Data for CpEtW(NO)(H)(η3-C5H9) Containing an
Endo Monosubstituted Allyl Ligand (13%).
3
1H NMR (400 MHz, C6D6): δ −1.49 (s, 1JHW = 120.9, 1H, WH), 1.08
3
i
3
(d, JHH = 6.9, 6H, Pr CH3), 1.45 (m, 1H, allyl CH), 2.06 (d, JHH
=
5.7, 3H, allyl Me), 2.19 (m, 1H, allyl CH), 2.34 (d, 3JHH = 5.8, 3H, allyl
Me), 2.45 (sept, 3JHH = 6.9, 1H, iPr CH), 4.32 (dd, 3JHH = 12.5, 3JHH
=
i
9.9, 1H, allyl meso CH), 4.55 (m, 1H, C5H4 Pr), 4.74 (m, 1H,
C5H4 Pr), 4.96 (m, 1H, C5H4 Pr), 5.18 (m, 1H, C5H4 Pr). 13C NMR
(100 MHz, C6D6): δ 20.0 (allyl Me), 22.1 (allyl CH3), 24.1 (i-Pr CH),
47.7 (allyl CH), 66.4 (allyl CH), 90.9 (C5H4(i-Pr)), 91.2 (C5H4(i-Pr)),
94.0 (C5H4(i-Pr)), 94.5 (C5H4(i-Pr)), 107.2 (allyl meso CH).
i
i
i
Partial Characterization Data for CpiPrW(NO)(H)(η3-C5H9) Con-
taining an Endo Monosubstituted Allyl Ligand (11%). 1H NMR
(400 MHz, C6D6): δ −1.34 (s, 1JHW = 122.0, 1H, WH), 4.21 (ddd, 3JHH
1H NMR (400 MHz, C6D6): δ −1.40 (s, 1JHW = 121.5, 1H, WH), 0.62
(d, 3JHH = 13.5, 1H, C1H2), 0.85 (t, 3JHH = 7.6, 3H, C5Me4(CH2Me)),
= 13.1, JHH = 10.4, JHH = 7.4, 1H, allyl CH). 13C NMR (100 MHz,
3
3
3
1.09 (m, 1H, C3H) 1.18 (t, JHH = 7.4, 3H, C5H3), 1.73 (s, 3H,
C6D6): δ 104.1 (allyl CH).
Computational Methods. Density functional theory12 was
applied to determine the structural and energetic features of the com-
plexes described herein. All theoretical calculations were performed
using Gaussian09 (version D.01).13 The 6-31+G(d) basis set14 was
used for all atoms (C, H, O, N) except W and Mo, which were treated
using the Stuttgart pseudopotential and associated basis set.15 The
hybrid exchange correlation functional PBE0 was also used.16 All
structures were calculated without any geometrical constraints, and all
stationary points were characterized as minima or transition states by
frequency calculations. Solvent effects (n-pentane) were included in all
structure-optimization and frequency calculations using the PCM
solvation model of Tomasi et al. as implemented in the Gaussian
code.17 No explicit solvent modeling was required because of the
extremely low coordinating properties of the hydrocarbon solvents
involved in the modeled reactions. All complexes investigated were
diamagnetic; consequently, all corresponding structures were opti-
mized in the singlet spin state.
C5Me4(CH2Me)), 1.74 (s, 3H, C5Me4(CH2Me)), 1.77 (s, 3H,
C5Me4(CH2Me)), 1.80 (s, 3H, C5Me4(CH2Me)), 2.13 (obs, 2H,
C4H2), 2.18 (q, 3JHH = 7.4, 2H, C5Me4(CH2Me)), 4.09 (d, 3JHH = 7.1,
1H, C1H2), 4.32 (ddd, 3JHH = 13.5, 3JHH = 10.0, 3JHH = 7.1, 1H, C2H).
13C NMR (100 MHz, C6D6): δ 10.5 (C5Me4(CH2Me)), 10.7
(C5Me4(CH2Me)), 10.8(C5Me4(CH2Me)), 15.9 (C5Me4(CH2Me)),
19.6 (C5H3), 19.8 (C5Me4(CH2Me)), 27.7 (C4H2), 52.2 (C1H2),
67.2 (C3H), 103.3 (C2H), 104.2 (C5Me4(CH2Me)), 104.4
(C5Me4(CH2Me)), 104.9 (C5Me4(CH2Me)), 105.4 (C5Me4(CH2Me))
110.3 (C5Me4(CH2Me)).
Partial Characterization Data for CpEtW(NO)(H)(η3-C5H9) Con-
taining an Exo Monosubstituted Allyl Ligand (12%).
1H NMR (400 MHz, C6D6): δ −1.28 (s, 1H, WH).
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the ACS
Publications website at DOI: 10.1021/acs.organomet.7b00034.
Reaction of CpiPrW(NO)(CH2CMe3)2 with n-Pentane. In a
glovebox a reaction flask was charged with CpiPrW(NO)(CH2CMe3)2
(0.299 g, 0.645 mmol) and dried n-pentane (ca. 40 mL). The flask was
sealed with a Kontes greaseless stopcock, and then its stirred contents
were thermalized for 2 days at 60 °C to produce a brown mixture.
Solvent removal in vacuo yielded a dark brown residue that was
purified by flash chromatography on silica. A yellow band was eluted
with a gradient of 0−20% EtOAc in hexanes, and solvent was removed
from the eluate in vacuo to obtain CpiPrW(NO)(H)(η3-C5H9) as a
dark yellow oil (0.043 g, 0.11 mmol, 17% yield). In solution three
isomers of CpiPrW(NO)(H)(η3-C5H9) have been identified by 1H and
13C NMR spectroscopy.
■
S
Full details of the preparation and characterization
(including single-crystal X-ray diffraction analyses) of
CpEtW(NO)(CO)2, CpEtW(NO)(CH2CMe3)2, and
CpEtW(NO)(H)(η3-CH2CHCMe2), descriptions of repre-
sentative experiments performed to obtain the data
presented in Tables 2 and 3, NMR spectra of repre-
sentative complexes, and optimized structure and final
thermochemical parameters of the various complexes
subjected to DFT calculations (PDF)
Characterization Data for CpiPrW(NO)(H)(η3-C5H9) Containing an
Endo Monosubstituted Allyl Ligand (44%).
Cartesian coordinates of the calculated structures (XYZ)
Accession Codes
CCDC 1550806−1550808 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.
IR (cm−1): 1610 (s, νNO). MS (LREI, m/z, probe temperature 150 °C):
1
1
391 [M+, 184W]. H NMR (400 MHz, C6D6): δ −1.54 (s, JHW
=
115.6, 1H, WH), 0.78 (m, 1H, allyl C1H2), 1.08 (d, 3JHH = 6.9, 6H, iPr
3
CH3), 1.13 (t, JHH = 3.7, 3H, allyl C5H3), 1.97−2.04 (m, 2H, allyl
3
i
C4H2), 2.42 (m, 1H, allyl C3H), 2.61 (sept, JHH = 6.9, 1H, Pr CH),
3
2
2.84 (dt, JHH = 7.0, JHH = 2.7, 1H, allyl C1H2), 4.44 (m, 1H, allyl
AUTHOR INFORMATION
Corresponding Author
*E-mail for P.L.: legzdins@chem.ubc.ca.
■
i
i
C2H), 4.61 (m, 1H, C5H4 Pr), 4.83 (m, 1H, C5H4 Pr), 5.01 (m, 1H,
i
i
C5H4 Pr), 5.15 (m, 1H, C5H4 Pr). 13C NMR (100 MHz, C6D6): δ 17.6
(allyl C5H3), 24.0 (i-Pr CH), 32.3 (allyl C1H), 80.5 (allyl C3H),
90.8 (C5H4(i-Pr)), 91.7 (C5H4(i-Pr)), 93.5 (C5H4(i-Pr)), 93.7
(C5H4(i-Pr)), 100.7 (allyl C2H), 125.0 (ipso-C5H4(i-Pr)).
ORCID
Guillaume P. Lefevre: 0000-0001-9409-5861
̀
L
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.;
Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin,
K. N.; Staroverov, V. N.; Keith, T.; Kobayashi, R.; Normand, J.;
Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.;
Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.;
Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.;
Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.;
Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador,
P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.;
Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09,
Revision D.01; Gaussian, Inc., Wallingford, CT, 2013.
Peter Legzdins: 0000-0002-3914-3768
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We are grateful to The Dow Chemical Company for financial
support of our work and to our Dow colleagues, Andy Arthur
and Brian Kolthammer, for assistance and helpful discussions.
We thank Alan S. Goldman for insight and technical assistance,
Joseph M. Clarkson for developing the method employed for
GC/FID analyses, and Taleah M. Levesque and Maria Ezhova
for carrying out the deuterium labelling study. P.L. is also
grateful to the reviewers for their helpful suggestions and
comments. R.A.B. acknowledges the NSERC of Canada for an
award of a PGSD postgraduate scholarship. This research has
been enabled by the use of WestGrid computing resources,
which are funded in part by the Canada Foundation for
Innovation, Alberta Innovation, Science BC Advanced Educa-
tion, and the participating research institutions. WestGrid
equipment is provided by IBM, Hewlett-Packard, and SGI.
(14) Krishnan, R.; Binkley, J. S.; Seeger, R.; Pople, J. A. Self-
consistent Molecular Orbital Methods. XX. A Basis Set for Correlated
Wave Functions. J. Chem. Phys. 1980, 72, 650−654.
(15) von Szentpal
́
y, L.; Fuentealba, P.; Preuss, H.; Stoll, H.
Pseudopotential Calculations on Rb+ , Cs+ , RbH+, CsH+ and the
2
2
Mixed Alkali Dimer Ions. Chem. Phys. Lett. 1982, 93, 555−559.
(16) Adamo, C.; Barone, V. Toward Reliable Density Functional
Methods Without Adjustable Parameters: The PBE0Model. J. Chem.
Phys. 1999, 110, 6158−6170.
̌
(17) (a) Miertus, S.; Scrocco, E.; Tomasi, J. Electrostatic Interaction
of a Solute with a Continuum. A Direct Utilization of Ab Initio
Molecular Potentials for the Prevision of Solvent Effects. Chem. Phys.
1981, 55, 117−129. (b) Scalmani, G.; Frisch, M. J.; Mennucci, B.;
Tomasi, J.; Cammi, R.; Barone, V. Geometries and Properties of
Excited States in the Gas Phase and in Solution: Theory and
Application of a Time-dependent Density Functional Theory
Polarizable Continuum Model. J. Chem. Phys. 2006, 124, 094107.
REFERENCES
■
(1) Baillie, R. A.; Legzdins, P. The Rich and Varied Chemistry of
Group 6 Cyclopentadienyl Nitrosyl Complexes. Coord. Chem. Rev.
2016, 309, 1−20.
(2) Pamplin, C. B.; Legzdins, P. Thermal Activation of Hydrocarbon
C−H Bonds by Cp*M(NO) Complexes of Molybdenum and
Tungsten. Acc. Chem. Res. 2003, 36, 223−233.
(3) Choi, J.; MacArthur, A. H. R.; Brookhart, M.; Goldman, A. S.
Dehydrogenation and Related Reactions Catalyzed by Iridium Pincer
Complexes. Chem. Rev. 2011, 111, 1761−1779.
̀
(4) Baillie, R. A.; Holmes, A. S.; Lefevre, G. P.; Patrick, B. O.; Shree,
M. V.; Wakeham, R. J.; Legzdins, P.; Rosenfeld, D. C. Synthesis,
Characterization, and Some Properties of Cp*W(NO)(H)(η3-allyl)
Complexes. Inorg. Chem. 2015, 54, 5915−5929.
̀ ́
(5) Baillie, R. A.; Wakeham, R. J.; Lefevre, G. P.; Bethegnies, A.;
Patrick, B. O.; Legzdins, P.; Rosenfeld, D. C. Thermal Chemistry of
Cp*W(NO)(H)(η3-allyl) Complexes. Organometallics 2015, 34,
3428−3441.
(6) Legzdins, P.; Martin, D. T. Organometallic Nitrosyl Chemistry. 8.
Preparation and Characteristic Chemistry of (η5-C5H5)W(NO)2H and
its Group 6B Congeners. Inorg. Chem. 1979, 18, 1250−1254.
(7) Aoki, T.; Crabtree, R. H. Homogeneous Tungsten, Rhenium, and
Iridium Catalysts in Alkane Dehydrogenation Driven by Reflux of
Substrate or of Cosolvent or by Inert-gas Flow. Organometallics 1993,
12, 294−298.
(8) Yao, W.; Zhang, Y.; Jia, X.; Huang, Z. Selective Catalytic Transfer
Dehydrogenation of Alkanes and Heterocycles by an Iridium Pincer
Complex. Angew. Chem., Int. Ed. 2014, 53, 1390−1394.
(9) Armarego, W. L. F.; Chai, C. L. L. Purification of Laboratory
Chemicals, 5th ed.; Elsevier: Amsterdam, 2003.
(10) Debad, J. D.; Legzdins, P.; Rettig, S. J.; Veltheer, J. E. Reactivity
of the Lewis acids Cp*M(NO)(CH2CMe3)Cl [M = Molybdenum,
Tungsten] and Related Complexes. Organometallics 1993, 12, 2714−
2725.
(11) Fabulyak, D.; Handford, R. C.; Holmes, A. S.; Levesque, T. M.;
Wakeham, R. J.; Patrick, B. O.; Legzdins, P.; Rosenfeld, D. C. Thermal
Chemistry of Cp*W(NO)(CH2CMe3)(H)(L) Complexes (L = Lewis
Base). Inorg. Chem. 2017, 56, 573−582.
(12) Parr, R. G.; Yang, W. Density-Functional Theory of Atoms and
Molecules; Oxford University Press: Oxford, U.K., 1989.
(13) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
M
DOI: 10.1021/acs.organomet.7b00034
Organometallics XXXX, XXX, XXX−XXX