Toward alkane functionalization effected with CpW(NO)(alkyl) (η3-allyl) Complexes

Article abstract of DOI:10.1021/om900307p

Cp*W(NO)(η-alkyl)(η³-allyl) complexes result from the selective activations of the terminal C-H bonds of alkanes. Consequently, the reactions of prototypical members of this family of complexes with a range of electrophiles and nucleophiles hav

Full text of DOI:10.1021/om900307p

4480 Organometallics 2009, 28, 4480–4490
DOI: 10.1021/om900307p
Toward Alkane Functionalization Effected with
Cp*W(NO)(alkyl)(η3-allyl) Complexes
Scott P. Semproni, Peter M. Graham, Miriam S. A. Buschhaus, Brian O. Patrick, and
Peter Legzdins*
Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
Received April 22, 2009
Cp*W(NO)(n-alkyl)(η3-allyl) complexes result from the selective activations of the terminal C-H
bonds of alkanes. Consequently, the reactions of prototypical members of this family of complexes
with a range of electrophiles and nucleophiles have been explored with a view to developing methods
for functionalizing the newly formed alkyl ligands. The two principal complexes investigated in this
regard have been Cp*W(NO)(CH2SiMe3)(η3-CH2CHCHMe) (1) and Cp*W(NO)(CH2C6H5)-
(η3-CH2CHCHMe) (2). It has been found that treatment of 1 and 2 with the oxidant I2 at -60 °C
produces Cp*W(NO)I2 and terminally functionalized ICH2SiMe3 and ICH2C6H5, respectively.
Oxidation of 1 by H2O2 also results in the loss of the allyl ligand and production of the known oxo
peroxo complex Cp*W(O)(η2-O2)(CH2SiMe3). Treatment of 1 and 2 with electrophiles affords the
products resulting from addition of the electrophile to the electron-rich terminus of the σ-π distorted
allyl ligands in the reactants. Thus, reagents of the type E-X (E = triphenylcarbenium, H,
catecholborane; X = Cl, BF4) liberate CH3CHdCHCH2E and form the organometallic products
Cp*W(NO)(X)(CH2SiMe3) and Cp*W(NO)(X)(CH2C6H5), respectively. Exposure of the tungsten
alkyl allyl complexes to isocyanide reagents leads to the formation of complexes bearing β,γ-
unsaturated η2-iminoacyl ligands that apparently arise from the migratory insertion of isocyanide
into the tungsten-allyl linkages. For instance, reaction of 1 with 2,6-xylylisocyanide produces Cp*W-
(NO)(CH2SiMe3)(η2-CH3CHCHCH2CdNC6H3Me2) (4a). Interestingly, gentle heating or chroma-
tography of 4a causes isomerization of the olefin and conversion to the conjugated product Cp*W-
(NO)(CH2SiMe3)(η2-CH3CH2CHCHCdNC6H3Me2) (4b). A similar reaction of 2 with 2,6-xylyliso-
cyanide affords both unconjugated and conjugated isocyanide insertion products, while treatment of 2
with n-butylisocyanide produces primarily the conjugated product. Finally, exposure of these tungsten
alkyl allyl complexes to 1000 psi of CO gas generally results in the desired migratory insertion of the CO
into the metal-alkyl linkages to form acyl compounds. Hence, 1 is first converted into Cp*W(NO)-
(C(O)CH2SiMe3)(η3-CH2CHCHMe), which then subsequently transforms into isolable Cp*W(NO)-
(C(O)CH3)(η3-CH2CHCHMe) (7). Interestingly, 2 does not react with CO under these experi-
mental conditions. Nevertheless, the generality of this mode of reactivity is established by the fact
that similar treatment of four other Cp*(W)(NO)(CH2CMe3)(η3-allyl) complexes with CO gas at
elevated pressures does afford the corresponding acyl products (8-11). All new organometallic
complexes have been characterized by conventional spectroscopic and analytical methods, and the
solid-state molecular structures of several compounds have been established by X-ray crystallographic
analyses.
Introduction
hydrogen becoming involved in a direct metal-hydride
interaction or being stored elsewhere in the metal’s coordi-
nation sphere.2,3 Systems that activate the sp3 C-H bonds of
alkanes remain relatively rare, and those that can combine
The selective activation and subsequent functionalization
of hydrocarbon C-H bonds by transition-metal complexes
continues to be a topic of current interest for synthetic
chemists.1-3 C-H bond activation by metal complexes
frequently involves cleavage of the C-H bond and forma-
tion of a new metal-carbon bond, with the corresponding
(3) For leading reviews and books on the topic of C-H activation at
transition-metal centers, see: (a) Bergman, R. G. Nature 2007, 446, 391.
(b) Arndtsen, B. A.; Bergman, R. G.; Mobley, T. A.; Peterson, T. H. Acc.
Chem. Res. 1995, 28, 154. (c) Crabtree, R. H. Chem. Rev. 1985, 85, 245.
(d) Crabtree, R. H. Chem. Rev. 1995, 95, 987, and references therein.
(e) Labinger, J. A.; Bercaw, J. E. Nature 2002, 417, 507. (f ) Activation and
Functionalization of C-H Bonds; Goldberg, K. I., Goldman, A. S., Eds.;
ACS Symposium Series 885; American Chemical Society: Washington, DC,
2004. (g) Periana, R. A.; Bhalla, G.; Tenn, W. J.; Young, K. J. H.; Liu, X. Y.;
Mironov, O.; Jones, C. J.; Ziatdinov, V. R. J. Mol. Catal. A: Chem. 2004,
220, 7. (h) Crabtree, R. H. Dalton Trans. 2001, 2437. (i) Shilov, A. E.;
Shul'pin, G. B. Chem. Rev. 1997, 97, 2879.
*Corresponding author. E-mail: legzdins@chem.ubc.ca.
(1) Handbook of C-H Transformations: Applications in Organic Syn-
thesis; Dyker, G., Ed.; Wiley-VCH: Weinheim, 2005.
(2) Activation and Catalytic Reactions of Saturated Hydrocarbons in
the Presence of Metal Complexes; Shilov, A. E., Shulpin, G. B., Eds.;
Kluwer: Boston, MA, 2000.
r
pubs.acs.org/Organometallics
Published on Web 06/23/2009
2009 American Chemical Society

Article
Organometallics, Vol. 28, No. 15, 2009 4481
alkane activation with subsequent functionalization of
the alkyl ligand are even more unique.3 In this connection
three systems that both activate and functionalize alkane
C-H bonds merit special mention since they employ
relatively mild reaction conditions and produce functiona-
lized molecules in good yields. These functionalizations
involve the selective oxidation of alkanes in aqueous
solution by soluble Pt(II) and Pt(IV) salts first described
by Shilov and co-workers,3i the catalytic conversion of
methane to methyl bisulfate mediated by ligated Pt(II)
complexes reported by Periana and co-workers,4 and the
catalytic, regioselective functionalization of alkanes using
transition-metal boryl complexes developed by Hartwig
and co-workers.5
One of our recent contributions to this area involved the
synthesis and characterization of several Cp*W(NO)(alkyl)-
(η3-allyl) complexes6 and the discovery that one of them,
namely, Cp*W(NO)(CH2CMe3)(η3-CH2CHCHMe), effects
single C-H activations at the terminal positions of n-alkanes
such as heptane, pentane, ethane, and methane at room
temperature.7 This nitrosyl complex displays remarkable
selectivity for primary over secondary positions, and the
Cp*W(NO)(n-alkyl)(η3-CH2CHCHMe) products resulting
from the C-H activation processes are isolable at room
temperature.
Results and Discussion
Syntheses of Cp*W(NO)(CH2SiMe3)(η3-CH2CHCHMe)
(1) and Cp*W(NO)(CH2C6H5)(η3-CH2CHCHMe) (2). The
18e complexes 1 and 2 were first prepared by the C-H
activation of tetramethylsilane and toluene, respectively,
by Cp*W(NO)(η2-CH2dCHCHdCH2).7 However, they
are most conveniently obtained on a preparative scale in
good yields by metathesis reactions originating with Cp*W-
(NO)Cl2.6 Both 1 and 2 exhibit diagnostic 1H NMR signals
in C6D6 indicative of their possessing piano-stool molecular
geometries in solution with the allyl ligands being in endo
conformations pointing away from the bulky Cp* rings and
displaying significant σ-π distortions.6 X-ray crystallo-
graphic analyses of both compounds have confirmed these
inferences. Complex 2 exhibits just the syn isomer in the solid
state, and its NMR data are consistent with this structure
being maintained in solutions.7 Complex 1, on the other
hand, exists as a 2:1 mixture of geometrical isomers in
solution and in the solid state.6 Its major isomer has the
methyl group of the 1-methylallyl ligand in the syn orienta-
tion, pointing toward the less bulky NO ligand, while the
minor isomer has it in the same orientation but pointing
toward the much larger CH2SiMe3 fragment.6
1
The H NMR spectrum of 1 in C6D6 reveals a pair of
doublets at -0.62 and -0.09 ppm due to the diastereotopic
methylene protons of CH2SiMe3. Similarly, complex 2 dis-
plays resonances at 1.95 and 2.82 ppm, which can be
attributed to the CH2C6H5 protons. Both complexes also
exhibit a multiplet at approximately 5 ppm attributable to
the meso proton of the allyl ligand. These spectral features
are particularly useful for monitoring the progress of reac-
tions involving 1 and 2.
Reactions of 1 and 2 with Oxidizing Agents. The reactivity
of molecular iodine with complexes 1 and 2 is identical to that
exhibited by related n-alkyl tungsten complexes and is
summarized in eq 1. As briefly noted previously,7 both the
alkyl and allyl ligands are liberated from the tungsten’s
coordination sphere with the Cp*W(NO) fragment being
recoverable as the diiodide.
To exploit more fully these unique C-H activations, we set
out to develop the conditions for effecting these activations
and subsequent functionalizations of the resulting alkyl
ligands in a catalytic manner. As a first step, we therefore
decided to investigate the reactions of the various Cp*W-
(NO)(alkyl)(η3-CH2CHCHMe) product complexes with a
range of electrophiles and nucleophiles to discover those
reagents that react preferentially with the alkyl ligands.
However, we quickly encountered a practical limitation.
On a preparative scale, Cp*W(NO)(R)(η3-allyl) [R = alkyl]
complexes are prepared via sequential metatheses reactions
of Cp*W(NO)Cl2 with MgR2 x(dioxane) and Mg(allyl)2 x-
3
3
(dioxane) reagents.6 Unfortunately, preparation of the R =
n-alkyl members of this family of complexes by this route is
not possible since the intermediate n-alkyl chloro complexes
are thermally unstable and readily decompose, probably by
β-hydrogen elimination. Since the desired Cp*W(NO)(n-
alkyl)(η3-allyl) reagents cannot be conveniently synthesized
on a large scale, we have instead employed two other
complexes that can be readily prepared by the metathesis
route, namely, Cp*W(NO)(CH2SiMe3)(η3-CH2CHCHMe)
(1) and Cp*W(NO)(CH2C6H5)(η3-CH2CHCHMe) (2), as
prototypical reactants during our studies. Subsequently,
the reactivity studies resulting in the desired functionaliza-
tion of the alkyl ligands were extended to encompass other
members of this family of complexes to establish the general-
ity of these transformations. To the best of our knowledge
such a study of the comparative reactivity of alkyl and allyl
ligands at the same metal center has not been undertaken
previously.
Compound 1 is also relatively stable toward oxygen and
moisture in the crystalline state. However, reaction of 1 with
aqueous hydrogen peroxide cleanly produces the known oxo
peroxo complex Cp*W(O)(η2-Ο2)(CH2SiMe3),8 readily
1
identifiable by its diagnostic H NMR resonances. A plau-
sible mechanism for the formation of the tungsten oxo
peroxo complex is presented in Scheme 1.
(4) Periana, R. A.; Taube, D. J.; Gamble, S.; Taube, H.; Satoh, T.;
Fujii, H. Science 1998, 280, 564.
(5) Chen, H.; Schlecht, S.; Semple, T. C.; Hartwig, J. F. Science 2000,
287, 1995.
(6) Tsang, J. Y. K.; Buschhaus, M. S. A.; Fujita-Takayama, C.;
Patrick, B. O.; Legzdins, P. Organometallics 2008, 27, 1634, and
references therein.
Precedent for the oxidatively induced intramolecular
insertion of NO into a tungsten-carbon bond depicted
in Scheme 1 is provided by the reaction summarized in
eq 2. Thus, we have recently discovered that treatment
of Cp*W(NO)(CH2SiMe3)2 with 1 equiv of cumene
(7) Tsang, J. Y. K.; Buschhaus, M. S. A.; Graham, P. M.; Semiao, C.
J.; Semproni, S. P.; Kim, S. J.; Legzdins, P. J. Am. Chem. Soc. 2008, 130,
3652.
ꢀ
(8) Phillips, E. C.; Sanchez, L.; Legzdins, P. Organometallics 1989, 8,
940.

4482 Organometallics, Vol. 28, No. 15, 2009
Semproni et al.
Scheme 1
Figure 1. Solid-state molecular structure of 3 with 50% probabil-
˚
hydroperoxide
OdNCH2SiMe3).9
produces
Cp*W(O)(CH2SiMe3)(η2-
ity thermal ellipsoids. Selected interatomic distances (A): C(1)-
C(2)=1.492(2), C(2)-C(3)=1.310(2), C(3)-C(4)=1.502(2).
Scheme 2
The hydroperoxide evidently delivers a single oxygen atom
to form initially an oxo species, which then undergoes
migratory insertion of the nitrosyl ligand into the W-C
bond. We believe that a similar mechanism is operative
during the conversion summarized in Scheme 1 with the
NO insertion first occurring into the metal-allyl linkage and
subsequent oxidation then producing the final oxo-peroxo
complex. Particularly intriguing in this regard is the fact that
it is the allyl, and not the alkyl, group that migrates with such
selectivity. The released nitrosoalkene depicted in Scheme 1
1
has not been detected by H NMR spectroscopy, and it is
probably unstable under the reaction conditions em-
ployed.10 In any event, the use of hydrogen peroxide results
in preferential functionalization of the allyl over the alkyl
ligand.
Reactions of 1 and 2 with Electrophilic Reagents. Nucleo-
philic attack on η3-allyl ligands in group 6 half-sandwich
compounds of this type is a common mode of reactivity and
usually occurs trans to the better π-accepting NO ligand.11 It
might therefore have been expected that electrophiles would
preferentially attack the alkyl ligands of the Cp*W(NO)-
(alkyl)(η3-allyl) reactants. However, every electrophilic re-
agent with which complexes 1 and 2 have been treated to
obtain an isolable product attacks the allyl ligands. No
functionalization of the alkyl ligands has been detected
under these experimental conditions.
Hence, treatment of 1 with HCl in MeCN-d3 affords ink
blue Cp*W(NO)(CH2SiMe3)Cl6 and probably 2-butene, the
direct result of electrophilic addition of Hþ to the allyl
ligand. The analogous reaction of 1 with pyridinium chloride
affords the same products. Finally, reaction of 1 with B-
chlorocatecholborane produces Cp*W(NO)(CH2SiMe3)Cl
and a borane-functionalized alkene, characterized by
multiplets at 1.30, 2.47, 5.07, and 6.10 ppm in the 1H
NMR spectrum of the final reaction mixture, which indicate
that it is principally the isomer shown in eq 3.
Treatment of 1 with triphenylcarbenium tetrafluorobo-
rate affords a crystalline white solid following extraction of
the final reaction mixture with pentane and subsequent
chromatography. An X-ray crystallographic analysis of the
crystalline material has confirmed it to be H3CCHCHCH2C-
(C6H5)3 (3) (Figure 1). The interatomic distance of 1.310(2)
˚
A between C2 and C3 is indicative of a carbon-carbon
double bond, and the trans orientation of the substituents is
evident from the solid-state molecular structure. The orga-
nometallic product of the reaction possesses an intact
CH2SiMe3 ligand, with the resonances attributable to the
diastereotopic protons appearing at -1.15 and 0.01 ppm. In
addition, singlets at 0.36 and 1.63 ppm correspond to SiMe3
and C5Me5 fragments, respectively. While the identity of this
product remains to be confirmed, a complex of the type
Cp*W(NO)(CH2SiMe3)(η1-BF4) can be postulated on the
(9) Graham, P. M.; Buschhaus, M. S. A.; Semproni, S. P.; Legzdins,
P. Unpublished observations.
(10) Bottomley, F.; Sutin, L. Adv. Organomet. Chem. 1988, 28, 339.
(11) (a) Adams, R. D.; Chodosh, D. F.; Faller, J. W.; Rosan, A. M. J.
Am. Chem. Soc. 1979, 101, 2570. (b) Vanarsdale, W. E.; Winter, R. E. K.;
Kochi, J. K. Organometallics 1986, 5, 645. (c) Faller, J. W.; Murray, H. H.;
White, D. L.; Chao, K. H. Organometallics 1983, 2, 400. (d) Pearson, A. J.;
Khan, Md. N. I.; Clardy, J. C.; Cunheng, H. J. Am. Chem. Soc. 1985, 107,
2748.

Article
Organometallics, Vol. 28, No. 15, 2009 4483
Scheme 3
basis of our previous work with iron nitrosyl complexes.12
Similar treatment of 2 with triphenylcarbenium tetrafluoro-
borate also affords 3 and an organometallic species bearing
distinctive resonance at 214.8 ppm due to the iminoacyl
carbon. An X-ray crystallographic analysis has been per-
formed on a single crystal of 4a, and its solid-state molec-
ular structure is shown in Figure 2. The crystal of complex
4a exhibited some disorder at the terminal positions of the
allyl ligand because of their rotational mobility, and so
only one of the two rotational isomers is shown in this
figure. Chromatography of a solution of 4a on alumina and
subsequent cooling of the eluate leads to the isolation of the
1
C5Me5 and CH2C6H5 ligands, characterized by H NMR
resonances at 1.63 (C5Me5), 1.70 (CH2C6H5), and 2.90
(CH2C6H5) ppm. Clearly, the steric bulk of the alkyl ligands
in 1 and 2 does not influence the site of electrophilic attack.
On the basis of the current experimental evidence a
plausible mechanism can be proposed for the formation of
compound 3 (Scheme 2). As noted before, the electronic
asymmetry extant at the metal center causes a σ-π distortion
of the allyl ligand. This feature results in the accumulation of
electron density on the terminal position of the allyl ligand
trans to the nitrosyl group, thereby creating a site for
electrophilic attack.
Electrophilic addition of the triphenylcarbenium ion to
the terminal position of the allyl ligand leads to the forma-
tion of a new carbon-carbon bond and places the positive
charge formerly residing on the triphenyl fragment onto the
meso position of the 1-methylallyl ligand. This 16e species
may then undergo cleavage of the remaining W-C σ-bond
and rearrange to produce compound 3 and the postulated
16e complex Cp*W(NO)(CH2SiMe3)(η1-BF4). No coordi-
nation of the CdC bond of compound 3 to the tungsten
center occurs probably because of steric interactions between
the bulky CPh3 and CH2SiMe3/CH2C6H5 fragments.
The mechanism proposed in Scheme 2 can also be applied
to the reactions of complexes 1 and 2 with other electro-
philes, including Hþ and B-chlorocatecholborane. In all
cases, electrophilic addition occurs at the allyl ligand, the
resulting olefin apparently does not coordinate to the metal
center, and a new, electronically unsaturated metal complex
is formed.
isomeric
Cp*W(NO)(CH2SiMe3)(η2-CH3CH2CHCHCd
NC6H3Me2) (4b). 13C{1H} NMR spectroscopy of 4b re-
veals that the resonance attributable to the iminoacyl
carbon remains at 214.8 ppm, but the peak due to the
CH2 unit of the former allyl ligand has shifted from 37.4 to
27.1 ppm. A single-crystal X-ray crystallographic analysis
of 4b has confirmed it to be the conjugated isomer of 4a
(Figure 3).
The η2-binding mode of the iminoacyl fragment of 4a is
clearly established by its intramolecular metrical parameters
(Figure 2). The W1-C14, W1-C5, and W1-N2 bond
lengths in 4a are indicative of single σ-bonds.13 The C5-
˚
N2 interatomic distance of 1.257(10) A indicates a carbon-
nitrogen bond order similar to that extant in free imines.14
Consequently, the bonding of the iminoacyl ligand to the
tungsten center in 4a is best described as consisting of a W-C
σ-bond and a WrN dative interaction that provides a total
of three electrons necessary for the Cp*W(NO)(alkyl) frag-
ment to achieve an 18e configuration while leaving the C-N
multiple bond unperturbed. The solid-state molecular struc-
ture of 4b (Figure 3) displays similar metrical parameters.
The conjugation of the alkene and imine functionalities is
also evident in the intramolecular metrical parameters of 4a
and 4b.
Reactions of 1 and 2 with Isocyanides: Synthesis of
η2-Iminoacyl Complexes. Treatment of the tungsten alkyl
allyl complexes with isocyanide reagents leads to the for-
mation of compounds bearing β,γ-unsaturated η2-imino-
acyl ligands arising from migratory insertion of isocyanide
into the tungsten-allyl linkages. Gentle warming of these
product complexes or their chromatography on alumina
results in isomerization of the newly formed ligands to
afford compounds containing conjugated R,β-unsaturated
η2-iminoacyl ligands (Scheme 3).
In a similar fashion, reaction of 2,6-xylylisocyanide with
complex 2 affords the unconjugated insertion product Cp*W-
(NO)(CH2C6H5)(η2-CH3CHCHCH2CdNC6H3Me2) (5a) as
the major component of a mixture also containing Cp*W-
(NO)(CH2C6H5)(η2-CH3CH2CHCHCdNC6H3Me2) (5b).
Complex 5a may be separated from the mixture by fractional
recrystallization and fully characterized. Chromatography of
the mixture on alumina leads to isomerization of 5a to 5b,
which can then be recrystallized and fully characterized. Treat-
ment of 2 with n-butylisocyanide leads immediately to the
formation of a 3:2 mixture of the conjugated insertion product
Cp*W(NO)(CH2C6H5)(η2-CH3CH2CHCHCdNC4H9) (6b)
Thus, reaction of 1 with 2,6-xylylisocyanide produces
Cp*W(NO)(CH2SiMe3)(η2-CH3CHCHCH2CdNC6H3Me2)
(4a), whose 13C{1H} NMR spectrum in C6D6 displays a
€
(13) Arndt, S.; Schrock, R. R.; Muller, P. Organometallics 2007, 26,
1279.
(14) Shah, F. U.; Akhter, Z.; Siddiqi, H. M. Appl. Organomet. Chem.
(12) Hayton, T. W.; McNeil, W. S.; Patrick, B. O.; Legzdins, P. J. Am.
Chem. Soc. 2003, 125, 12935.
2007, 21, 758.

4484 Organometallics, Vol. 28, No. 15, 2009
Semproni et al.
Scheme 4
Figure 2. Solid-state molecular structure of 4a with 50% prob-
˚
ability thermal ellipsoids. Selected interatomic distances (A) and
angles (deg): W(1)-C(5)=2.072(8), W(1)-N(2)=2.156(6), W(1)-
C(14)=2.197(7), C(1b)-C(2b)=1.51(3), C(2b)-C(3b)=1.29(2), C-
(3b)-C(4)=1.55(2), C(4)-C(5)=1.470(11), C(5)-N(2)=1.257(10),
W(1)-N(1)-O(1)=172.3(6).
Lewis base to the metal center as required for the first step
of the mechanism presented in Scheme 4 is provided by the
formation of the related Cp*Mo(NO)(CH2CMe3)(η1-C3H5)-
(PMe3) adduct upon the addition of PMe3 to the parent alkyl
allyl complex in benzene at 35 °C.15 Migratory insertion of the
isocyanide into the tungsten-allyl bond then produces an 18-
electron η2-iminoacyl complex. Isocyanide insertion into the
allyl ligand does not appear to be influenced by the bulk of
either the alkyl ligand or the isocyanide itself.
Carbonylation Reactions of Various Cp*W(NO)(alkyl)-
(η3-allyl) Complexes. Synthesis of the Corresponding Metal-
loacyl Complexes. Given the reactivity exhibited by the
various Cp*W(NO)(alkyl)(η3-allyl) complexes toward iso-
cyanides described in the preceding section, we anticipated
that their reactions with CO would probably proceed in a
similar manner. We were therefore pleasantly surprised to
discover that even though migratory insertion of the CO did
occur, it did not involve the tungsten-allyl linkages (as for
the isocyanides) but rather the desired tungsten-alkyl bonds
(Scheme 5). For instance, reaction of 1 with 1000 psi of CO
for 24 h at room temperature leads to insertion exclusively
into the W-CH2SiMe3 linkage. However, the trimethylsilyl
unit is subsequently released from the metalloacyl complex,
and the acetyl complex, 7, is the final complex formed. How
this happens remains to be ascertained. Compound 7 has
been fully characterized by conventional spectroscopic tech-
niques. Thus, its mass spectrum exhibits a signal with a
tungsten isotopic pattern at m/z = 447, corresponding to
the parent ion, and its IR spectrum as a Nujol mull displays
two strong bands at 1594 and 1615 cm-1, attributable to νNO
of a terminal nitrosyl and νCO of an η1-acyl ligand, respec-
tively. Consistently, its 13C{1H} NMR spectrum contains a
downfield peak at 258.6 ppm characteristic of a tungsten-
acetyl species.16 An X-ray crystallographic analysis of 7 has
been attempted; even though the atom connectivity of the
complex could be confirmed, neither an acceptable ORTEP
plot nor meaningful metrical parameters could be generated
due to the presence of significant disorder in the crystal.
Figure 3. Solid-state molecular structure of 4b with 50% prob-
˚
ability thermal ellipsoids. Selected interatomic distances (A) and
angles (deg): W(1)-C(5)=2.0873(19), W(1)-C(14)=2.211(2), W-
(1)-N(2)=2.1315(16), C(1)-C(2)=1.482(5), C(2)-C(3)=1.483-
(4), C(3)-C(4) = 1.319(4), C(4)-C(5) = 1.439(3), C(5)-N(2) =
1.260(2), W(1)-N(1)-O(1)=170.73(17).
1
with the unconjugated isomer (6a), as judged by H NMR
spectroscopy. Complex 6a cannot be characterized since at-
tempts to separate it from the reaction mixture by chromatog-
raphy result in its isomerization to 6b. Attempts to fractionally
recrystallize 6a from the crude reaction mixture have also been
unsuccessful. Regrettably, reaction of 1 with n-butylisocyanide
does not provide a tractable product.
A reasonable mechanism may be proposed to account for
the reactions of these alkyl allyl complexes with isocyanides.
The demonstrated affinity of the allyl ligand in these tung-
sten complexes for electrophilic reagents (vide supra) sug-
gests that a coordination-insertion mechanism of the type
presented in Scheme 4 is probably operative.
(15) Chow, C.; Semproni, S. P.; Legzdins, P. Unpublished observations.
(16) Sakaba, H.; Tsukamoto, M.; Kabuto, C.; Horino, H. Chem.
Lett. 2000, 12, 1404.
Precedent for the allyl ligand undergoing an η3 f η1
interconversion concomitant with the coordination of a

Article
Organometallics, Vol. 28, No. 15, 2009 4485
Scheme 5
Figure 4. Solid-state molecular structure of 8 with 50% prob-
˚
ability thermal ellipsoids. Selected interatomic distances (A) and
angles (deg): W(2)-C(21)=2.203(3), W(2)-C(29)=2.459(4), W-
(2)-C(28)=2.272(4), W(2)-C(27)=2.272(4), C(21)-O(4)=1.221-
(4), W(2)-N(2)-O(3)=169.1(3).
Nevertheless, the first step of the reaction with CO is
probably similar to that presented for isocyanides in
Scheme 4; namely, the allyl group must first undergo an
η3 f η1 haptotropic shift to open up a coordination position
at the metal center, thereby allowing coordination of CO and
subsequent insertion into the metal-alkyl bond. Following
insertion, the allyl group then undergoes an η1 f η3 hapto-
tropic shift to form the final 18e metalloacyl complex.
Somewhat surprisingly, similar treatment of 2 with 1000
psi of CO at 20 °C leaves the starting material unchanged.
This lack of reactivity probably reflects the fact that the CO
simply cannot gain access to the metal center in the presence
of a benzyl ligand that can also coordinate in an η3-fashion to
the metal center should the allyl ligand undergo an η3 f η1
haptotropic shift.17 Nevertheless, four other Cp*W(NO)-
(CH2CMe3)(η3-allyl) complexes that have been studied to
date form the corresponding acyl complexes 8-11 when
exposed to pressures of CO (Scheme 5). Compounds 8-11
have been fully characterized by customary spectroscopic
techniques, and the solid-state molecular structures of 8-10
have been established by single-crystal X-ray crystallo-
graphic analyses (Figures 4-6). Interestingly, complex 8 is
the only one of these compounds to exist as the exo, syn
isomer in the solid state.18
The carbonylation reactions of these tungsten alkyl allyl
complexes have not yet been optimized. Careful adjustment
of solvents, pressures, and reaction times may well lead to
significant improvements in the yields of these transforma-
tions. Nevertheless, since the tungsten-alkyl bonds result
from the activation of the terminal C-H bonds of hydro-
carbons, the synthesis of the desired tungsten acyl complexes
in this manner represents a significant step toward the
selective functionalization of alkanes mediated by these
tungsten compounds.
Figure 5. Solid-state molecular structure of 9 with 50% prob-
˚
ability thermal ellipsoids. Selected interatomic distances (A) and
angles (deg): W(1)-C(1)=2.240(5), W(1)-C(7)=2.377(6), W(1)-
C(8)=2.345(5), W(1)-C(9)=2.342(6), C(7)-C(8)=1.409(8), C-
(8)-C(9)=1.429(8), C(1)-O(2)=1.222(6).
W-allyl linkages and form initially complexes containing
β,γ-unsaturated η2-imine ligands. Isomerization to the con-
jugated R,β-unsaturated η2-imine complexes occurs sponta-
neously in solution. In contrast, CO gas under pressure
inserts preferentially into the tungsten-alkyl bonds and
affords the desired metalloacyl species. Future investigations
will focus on optimizing the yields of the carbonylation
products by modification of the reaction conditions. Addi-
tionally, the development of methods to release the newly
formed acyl ligands from the metal centers while keeping the
Cp*W(NO)(η3-allyl) fragments intact is also a high priority
for further studies. We shall report our results in these
regards in due course.
Epilogue. In summary, the characteristic reactivity of a
number of tungsten alkyl allyl complexes with a variety of
electrophilic and nucleophilic reagents has been investigated.
The allyl ligand is the preferred site of reactivity when
electrophiles are employed, leading to the liberation of
olefinic species. Isocyanides preferentially insert into the
Experimental Section
General Methods. All reactions and subsequent manipula-
tions involving organometallic reagents were performed under
anhydrous and anaerobic conditions under either high vacuum
or an inert atmosphere of prepurified dinitrogen. Purification of
inert gases was achieved by passing them first through a col-
(17) Legzdins, P.; Jones, R. H.; Phillips, E. C.; Yee, V. C.; Trotter, J.;
Einstein, F. W. B. Organometallics 1991, 10, 986.
(18) (a) Faller, J. W.; Rosan, A. M. J. Am. Chem. Soc. 1976, 98, 3388.
(b) Bi, S.; Ariafard, A.; Jia, G.; Lin, Z. Organometallics 2005, 24, 680.
˚
umn containing MnO and then a column of activated 4 A
molecular sieves. Conventional glovebox and Schlenk techni-
ques were utilized throughout. The gloveboxes utilized were

4486 Organometallics, Vol. 28, No. 15, 2009
Semproni et al.
were referenced to the residual protio isotopomer present in
C
C6D6 (7.15 ppm), CD3CN (1.94 ppm), or CDCl3 (7.24 ppm). 13
NMR spectra were referenced to C6D6 (128.4 ppm). When
1
necessary, H-1H COSY and 13C APT experiments were car-
ried out to correlate and assign 1H and 13C NMR signals. Low-
resolution mass spectra (EI, 70 eV) were recorded by the staff of
the UBC mass spectrometry facility using a Kratos MS-50
spectrometer. Elemental analyses were performed by Mr. David
Wong of the UBC microanalytical facility.
Synthesis of Cp*W(NO)(CH2SiMe3)(η3-CH2CHCHMe) (1).
Complex 1 was first prepared by the C-H activation of SiMe4.7
However, on a preparative scale it is best synthesized in
the following manner: Cp*W(NO)(CH2SiMe3)Cl (2.420 g,
5.138 mmol) was dissolved in Et2O (25 mL) in a Schlenk flask
to obtain an ink blue solution. Mg(CH2CHCHMe)2 x(dioxane)
3
(titer=112 g/mol R, 0.575 g, 5.139 mmol) was dissolved in Et2O
(30 mL) in a separate Schlenk flask to obtain a colorless
solution. The latter solution was then frozen at -196 °C under
a flow of dinitrogen, and the dark blue solution was cannulated
onto it dropwise over a period of 20 min. The mixture was
allowed to warm to room temperature over the course of 1 h
while being stirred, whereupon it became dark brown. The
volatile components were removed from the final reaction
mixture in vacuo. The remaining brown residue was dissolved
in pentane, and the solution was transferred to the top of an
alumina I column (3 ꢀ 6 cm). Elution of the column with
pentane developed a yellow band, which was eluted. The solvent
was removed from the eluate in vacuo to obtain 1 as a bright
yellow powder (1.73 g, 71% yield).
Figure 6. Solid-state molecular structure of 10 with 50% prob-
˚
ability thermal ellipsoids. Selected interatomic distances (A) and
angles (deg): W(1)-C(1)=2.220(5), W(1)-C(7)=2.333(4), W(1)-
C(8)=2.349(4), W(1)-C(9)=2.262(4), C(1)-O(2)=1.214(5), C-
(7)-C(8)-C(9)=116.7(4).
Innovative Technologies LabMaster 100 and MS-130 BG dual-
station models equipped with freezers maintained at -30 °C. All
glassware was heated in an oven to 275 °C to remove any
moisture and then cooled to room temperature under vacuum.
Small-scale reactions and NMR spectroscopic analyses were
conducted in J. Young NMR tubes equipped with Kontes
greaseless stopcocks. Pentane, diethyl ether (Et2O), benzene,
benzene-d6, and tetrahdydrofuran (THF) were dried over so-
dium/benzophenone ketyl and freshly distilled prior to use.
Acetonitrile (MeCN), acetonitrile-d3, and chloroform-d
(CDCl3) were dried over CaH2 and distilled prior to use.
Pyridinium chloride was prepared by addition of a 1.0 M
solution of hydrochloric acid (HCl) in Et2O to a solution of
pyridine in Et2O. The powdery white solid that precipitated
from Et2O was collected on a medium-porosity frit, then washed
with pentane, and finally dried in vacuo. Commercially avail-
able (CH2CHCHMe)MgCl (Aldrich, 0.5 M in THF), (PhCH2)-
MgCl (Aldrich, 1.0 M in Et2O), and (Me3SiCH2)MgCl (Aldrich,
1.0 M in Et2O) were transformed into the corresponding diallyl
and dialkyl magnesium agents according to literature proce-
dures.19,20 Cp*W(NO)Cl2,21 Cp*W(NO)(CH2SiMe3)Cl,22 and
Cp*W(NO)(CH2C6H5)Cl23 were prepared according to the
published procedures. All other chemicals were ordered from
commercial suppliers and used as received.
Anal. Calcd for C18H33NOSiW: C, 44.00; H, 6.77; N, 2.85.
Found: C, 44.04; H, 6.90; N, 2.85. IR: νNO 1593 cm-1. 1H NMR
(400 MHz, C6D6), two isomers are present in an approximately 3:1
2
ratio: δ (major isomer) -0.62 (d, JHH =13.2, 1H, CH2SiMe3),
-0.09 (d, 2JHH=13.2, 1H, CH2SiMe3), 0.37 (s, 9H, CH2SiMe3), 1.01
(m, 1H, allyl CHMe), 1.48 (s, 15H, C5Me5), 1.58 (d, 3JHH=13.8,
1H, allyl CH2), 1.88 (d, 3JHH=5.8, 3H, allyl CH3), 3.36 (d, 3JHH
=
7.0, 1H, allyl CH2), 5.10 (ddd, 3JHH=13.8, 9.4, 7.0, 1H, allyl CH), δ
2
(minor isomer) selected signals -0.76 (d, JHH = 13.2, 1H,
CH2SiMe3), -0.48 (d, 2JHH=13.2, 1H, CH2SiMe3), 0.40 (s, 9H,
CH2SiMe3), 1.34 (d, JHH = 5.8, 3H, allyl CH3), 1.49 (s, 15H,
3
C5Me5), 2.12 (m, 1H, allyl CH2), 2.24 (m, 1H, allyl CH), 4.61 (m,
1H, allyl CH). 13C{1H} NMR (150 MHz, C6D6): δ -6.2
(CH2SiMe3), 4.1 (CH2SiMe3), 10.3 (C5Me5), 17.1 (allyl CH3),
53.3 (allyl CHMe), 74.5 (allyl CH2), 106.5 (C5Me5), 114.2 (allyl
CH). MS (LREI, m/z, probe temperature 100 °C): 491 [Pþ, 184W].
Synthesis of Cp*W(NO)(CH2C6H5)(η3-CH2CHCHMe) (2).
Complex 2 was initially prepared by the C-H activation of
toluene.7 Large-scale synthesis was effected by metathesis as
follows: Cp*W(NO)(CH2C6H5)Cl (0.505 g, 1.062 mmol) and
Mg(CH2CHCHMe)2 x(dioxane) (titer=112 g/mol R, 0.118 g,
3
1.054 mmol) were reacted in the manner described in the
preceding section for 1. A yellow-green band was collected by
elution from alumina with a 1:1 pentane/Et2O mixture. The
solvent was removed in vacuo to obtain 2 as a light orange
powder (0.22 g, 43% yield).
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. NMR spectra
were recorded at room temperature on Bruker AV-300 or AV-
400 instruments, and all chemical shifts and coupling constants
1
Anal. Calcd for C21H30NOW: C, 50.82; H, 6.09; N, 2.82.
Found: C, 50.97; H, 5.97; N, 2.82. IR: νNO 1603 cm-1. 1H NMR
(400 MHz, C6D6): δ 1.25 (m, 1H, allyl CHMe buried), 1.47 (s,
are reported in ppm and in Hz, respectively. H NMR spectra
15H, C5Me5), 1.52 (d, 3JHH=13.6, 1H, allyl CH2) 1.76 (d, 3JHH
=
(19) Debad, J. D.; Legzdins, P.; Batchelor, R. J.; Einstein, F. W. B.
Organometallics 1993, 12, 2094.
5.9, 3H, allyl CH3), 1.95 (d, 2JHH=9.1, 1H, benzyl CH2), 2.82 (d,
2JHH=9.1, 1H, benzyl CH2), 3.43 (d, 3JHH=7.0, 1H, allyl CH2),
(20) There were instances when the isolation of the bis(allyl)magne-
sium reagent was unsuccessful, such as when removal of solvent left
behind an intractable oily material. In such cases the oily residue was
redissolved in Et2O, and the solution was used as such after the
concentration of the allylating reagent had been established by an HCl
titration. The Et2O solution was stored in a resealable glass bomb.
(21) Dryden, N. H.; Legzdins, P.; Batchelor, R. J.; Einstein, F. W. B.
Organometallics 1991, 10, 2077.
(22) Debad, J. D.; Legzdins, P.; Batchelor, R. J.; Einstein, F. W. B.
Organometallics 1992, 11, 6.
(23) Dryden, N. H.; Legzdins, P.; Trotter, J.; Yee, V. C. Organome-
tallics 1991, 10, 2857.
4.43 (ddd, 3JHH=13.6, 9.3, 7.0, 1H, allyl CH), 7.00 (d, 3JHH
=
7.4, 1H, para CH), 7.29 (t, 3JHH=7.4, 2H, meta CH), 7.51 (d,
2H, 3JHH=7.4, ortho CH). 13C{1H} NMR (150 MHz, C6D6): δ
9.8 (C5Me5), 17.5 (allyl CH3), 21.1 (benzyl CH2), 56.5 (allyl
CHMe), 77.0 (allyl CH2), 110.4 (allyl CH), 123.5 (Ar C), 128.1
(Ar C), 129.1 (Ar C). MS (LREI, m/z, probe temperature
100 °C): 495 [Pþ, 184W].
Reaction of 2 with I2. Complex 2 (24.0 mg, 0.051 mmol) was
dissolved in CDCl3 (1.5 mL) in a resealable glass vessel equipped

Article
Organometallics, Vol. 28, No. 15, 2009 4487
with a Kontes greaseless stopcock and containing a small stir
bar. HMDS (10 μL) was added via a microsyringe as an NMR
integration standard. The H NMR spectrum of a sample of
yellow to dark blue occurred over the course of 30 min. 1H NMR
spectroscopic analysis of the reaction mixture again confirmed
the formation of Cp*W(NO)(CH2SiMe3)Cl (vide supra).22
Reaction of 1 with B-Chlorocatecholborane. In the manner
described above, complex 1 (10 mg, 0.020 mmol) and B-chloro-
catecholborane (4 mg, 0.026 mmol) were dissolved in MeCN-d3
(1 mL) and combined. A color change from yellow to green-blue
occurred over the course of 1 h. NMR spectroscopic analyses of
the reaction mixture confirmed the formation of Cp*W(NO)-
(CH2SiMe3)Cl22 and an olefinic species, the borane-functiona-
lized alkene (cf. eq 3).
1
the mixture was recorded, and the area under the doublet at
3.40 ppm (1H, allyl CH2CHCHCH3) was integrated against the
singlet at 0.10 ppm (18H, HMDS). The NMR sample was
recombined with the rest of the solution, and the resealable
vessel was attached to a vacuum line and was maintained at
-60 °C with a dry ice/acetone bath. A solution of I2 (25.0 mg,
2 equiv) in CDCl3 (5 mL) was then introduced dropwise via a
cannula into the chilled resealable vessel. The cold bath was
removed after the addition of I2 was complete, and the reaction
mixture was stirred for 1 h as it warmed to room temperature.
Overall, the reaction mixture changed color from yellow to red-
orange. A small amount of the final reaction mixture was
transferred to an NMR tube, and the sample was analyzed by
1H NMR spectroscopy. Integration of the area under the singlet
at 4.47 ppm (2H, (C6H5)CH2I) against the HMDS signal
revealed that (iodomethyl)benzene had been formed in approxi-
mately 45% yield.
1H NMR (400 MHz, CD3CN): δ 0.43 (s, 9H, CH2SiMe3),
1.30 (d, 3H, 3JHH=7.3, MeCHB), 1.90 (s, 15H, C5Me5), 2.06 (br
s, 2H, CH2SiMe3), 2.42 (dt, 1H, JHH =14.5, 7.5, CHB) 5.07
3
(ddt, 2H, 3JHH=17.3, 10.2, 1.6, CHCH2), 6.10 (ddd, 1H, 3JHH
=
17.3, 10.2, 7.31, CHCH2), 6.96 (dd, 1H, JHH =5.7, 3.4, aryl
3
3
CH), 7.07 (dd, 1H, JHH = 5.7, 3.4, aryl CH), 7.11 (dd, 1H,
3JHH=5.9, 3.2, aryl CH), 7.25 (m, 1H, aryl CH). 13C{1H} NMR
(150 MHz, CD3CN): selected signals δ 3.6 (CH2SiMe3), 10.4
(C5Me5), 15.0 (MeCH), 112.5 (C5Me5), 112.7 (aryl C), 113.6
(aryl C), 115.7 (olefin C), 122.9 (aryl C), 124.0 (olefin C), 124.1
(aryl C), 150.2 (aryl C).
Reaction of 1 with I2. Complex 1 (40 mg, 0.081 mmol) was
dissolved in CDCl3 (1.5 mL) in a resealable glass vessel equipped
with a Kontes greaseless stopcock and containing a small stir
bar. C6H6 (10 μL) was added via a microsyringe as an NMR
integration standard. The reaction with I2 was performed as
described in the preceding paragraph. The final mixture was
analyzed by 1H NMR spectroscopy, and integration of the area
under the singlet at 0.17 ppm (9H, Me3SiCH2I) against the C6H6
signal revealed that (iodomethyl)trimethylsilane had been
formed in approximately 57% yield. The solvent was removed
in vacuo, and the yellow-green oil was triturated with pentane
(2 ꢀ 5 mL) to obtain a yellow-green solution. The solution was
transferred to the top of a Celite column (5 cm ꢀ 0.5 cm). Elution
of the column with pentane produced a green band, which was
collected. The solvent was removed from the eluate in vacuo,
and the green residue was analyzed by EI-MS. The presence of
Cp*W(NO)I2 was confirmed by a signal at m/z=603 [Pþ].24
Reaction of 1 with H2O2. A sample of 1 (16 mg, 0.033 mmol)
was dissolved in ethanol (5 mL) in a resealable glass vessel
equipped with a greaseless stopcock and a magnetic stirbar to
obtain a yellow solution. H2O2 (1.5 mL, 30% solution in H2O,
13.2 mmol) was added via pipet. The vessel was sealed, and the
mixture was stirred for 72 h at room temperature, whereupon a
gradual color change from yellow to colorless occurred. The
final reaction mixture was taken to dryness in vacuo, and the
white residue was subjected to 1H NMR spectroscopic analysis.
Diagnostic 1H NMR signals reveal the principal product to be
the previously reported Cp*W(O)(η2-Ο2)(CH2SiMe3).8
Reaction of 1 with Ph3CBF4. Asampleof1(22mg, 0.045mmol)
was dissolved in MeCN-d3 (0.5 mL) in a J. Young NMR tube
equipped with a Kontes greaseless stopcock to obtain a yellow
solution. To this solution was added a dark orange solution of
Ph3CBF4 (16 mg, 0.049 mmol) in MeCN-d3 (0.5 mL). The mixture
was stored for 18 h at ambient temperatures before being subjected
to a 1H NMR spectroscopic analysis.
2
1H NMR (400 MHz, C6D6): δ -1.15 (d, 1H, JHH = 11.4,
2
CH2SiMe3) 0.01 (d, 1H, JHH = 11.4, CH2SiMe3), 0.36 (s, 9H,
3
CH2SiMe3) 1.37 (d, 3H, JHH = 6.3, MeCHCH), 1.63 (s, 15H,
C5Me5), 3.32 (d, 2H, 3JHH=6.7, CH2CPh3), 5.37 (m, 1H, MeCH
or CHCHCH2), 5.40 (m, 1H, MeCH or CHCHCH2), 7.02 (d, 3H,
3JHH=7.4, para aryl CH), 7.09 (t, 6H, 3JHH=7.6, meta aryl CH),
7.26 (d, 6H, 3JHH=8.2, ortho aryl CH).
Removal of the volatile components from the final reaction
mixture in vacuo afforded an orange oil. Crystals of CH3-
CHCHCH2CPh3 (3) suitable for X-ray crystallographic analysis
were grown by storing a concentrated MeCN solution of the oil
at -30 °C overnight.
Reaction of 2 with Ph3CBF4. A sample of 2 (7 mg, 0.014 mmol)
was dissolved in MeCN (1 mL) to obtain an orange solution. To
this was added a solution of Ph3CBF4 (7 mg, 0.021 mmol) in
MeCN (1 mL). The mixture was left undisturbed for 18 h before
the volatile components were removed in vacuo. The orange
residue was subjected to 1H NMR spectroscopic analysis, which
confirmed the formation of 3 (vide supra).
1H NMR (400 MHz, C6D6): δ 0.45 (s, 9H, CH2SiMe3), 0.52
1H NMR (400 MHz, C6D6): δ 1.38 (d obscured, 3H,
MeCHCH), 1.63 (s, 15H, C5Me5), 1.70 (d, 1H, 2JHH=5.3, benzyl
CH2), 2.90 (d, 1H, 2JHH=5.3, benzyl CH2), 3.32 (d, 2H, 3JHH=6.3,
CH2CPh3), 5.30 (m, 1H, MeCH or CHCHCH2), 5.41 (m, 1H,
MeCH or CHCHCH2), 7.01 (m overlapping, 3H, aryl CH), 7.07
(m overlapping, 6H, aryl CH), 7.28 (m overlapping, 6H, aryl CH).
Preparation of Cp*W(NO)(CH2SiMe3)(η2-CH3CHCHCH2-
CdNC6H3Me2) (4a). A sample of 1 (21.0 mg, 0.043 mmol) was
dissolved in Et2O (1 mL) in a 4-dram vial to obtain a yellow
solution. To this was added a solution of CNC6H3Me2 (5.0 mg,
0.038 mmol) in Et2O (1 mL), and the mixture was left to stand
for 2 h. The solvent was then removed from the solution in
vacuo, and the residue was redissolved in a minimum amount of
Et2O. The Et2O solution was stored overnight at -30 °C to
induce deposition of 4a as yellow microcrystals (17.0 mg, 80%
yield).
2
(d, 1H, JHH = 12.5, CH2SiMe3) 0.93 (d, 1H, JHH = 12.5,
2
CH2SiMe3), 1.58 (s, 15H, C5Me5).
Reaction of 1 with HCl. A sample of 1 (30 mg, 0.061 mmol)
was dissolved in MeCN-d3 (1 mL) in a J. Young NMR tube
equipped with a Kontes greaseless stopcock to obtain a yellow
solution. To this solution was added a solution of HCl in Et2O
(0.1 mL, 2.0 M, 0.2 mmol), whereupon an immediate color
1
change from light yellow to dark blue occurred. A H NMR
spectrum of the crude reaction mixture confirmed the formation
of previously characterized Cp*W(NO)(CH2SiMe3)Cl.22
1H NMR (400 MHz, CD3CN): δ 0.08 (s, 9H, CH2SiMe3),
1.91 (s, 15H, C5Me5), 2.06 (m, 2H, CH2SiMe3).
Reaction of 1 with Pyridinium Chloride. A sample of 1 (30 mg,
0.061 mmol) was dissolved in MeCN-d3 (1 mL) in a J. Young
NMR tube equipped with a Kontes greaseless stopcock to
obtain a yellow solution. A solution of pyridinium chloride
(14 mg, 0.12 mmol) in MeCN-d3 (0.5 mL) was added all at once,
and the NMR tube was sealed. A gradual color change from
Anal. Calcd for C27H42N2OSiW: C, 52.09; H, 6.80; N, 4.50.
Found: C, 52.24; H, 6.85; N, 4.43. IR: νNO 1553 cm-1. 1H NMR
(400 MHz, C6D6): δ-0.44 (d, 2JHH=13.3, 1H, CH2SiMe3), 0.12 (d
obscured, 1H, CH2SiMe3), 0.30 (s, 9H, CH2SiMe3), 1.40 (d, 3JHH
=
6.3, 3H, CHMe), 1.64 (s, 3H, aryl Me), 1.77 (s, 15H, C5Me5), 2.04
(24) Dryden, N. H.; Legzdins, P.; Einstein, F. W. B.; Jones, R. H.
Can. J. Chem. 1988, 66, 2100.
(s, 3H, aryl Me), 2.95 (dd, 2JHH=17.2, 5.5, 1H, CCH2CH), 3.54

4488 Organometallics, Vol. 28, No. 15, 2009
Semproni et al.
(dd, 2JHH=18.4, 5.9, 1H, CCH2CH), 5.26 (m, 1H, CHMe), 5.39
(m, 1H, CHCH2), 6.88 (m overlapping, 3H, aryl CH). 13C{1H}
NMR (150 MHz, C6D6): δ 2.5 (CH2SiMe3), 3.8 (CH2SiMe3), 10.6
(C5Me5), 18.9 (CHCH3), 19.4 (aryl CH3), 37.4 (CH2CH), 108.3
(C5Me5), 123.0 (CH2CH), 126.8 (Ar C), 129.6 (Ar C), 130.6 (Ar C),
131.0 (Ar C), 138.4 (Ar C), 156.6 (CHCH), 214.8 (CNCH). MS
(LREI, m/z, probe temperature 100 °C): 622 [Pþ, 184W].
1H, benzyl CH2), 6.45 (d, 3JHH=15.3, 1H, NCCH), 6.88 (m, 1H,
CH2CHCH), 7.00-7.41 (m, 8H, aryl CH). 13C{1H} NMR (150
MHz, C6D6): δ 10.6 (C5Me5), 12.8 (CH2Me), 18.4 (ArMe), 19.6
(ArMe), 27.0 (MeCH2), 34.8 (CH2C6H5), 108.4 (C5Me5), 122.2
(CHCHCN), 126.6 (Ar C), 127.4 (Ar C), 129.7 (Ar C), 131.4 (Ar
C), 132.9 (Ar C), 152.9 (Ar C), 157.9 (CHCN), 214.7 (NC). MS
(LREI, m/z, probe temperature 100 °C): 626 [Pþ, 184W]. MS
(HREI, m/z, probe temperature 120 °C): Pþ calcd for
C30H38N2OW: 626.24937, found 626.24936.
Preparation of Cp*W(NO)(CH2SiMe3)(η2-CH3CH2CHCH-
CdNC6H3Me2) (4b). A sample of 1 (24.0 mg, 0.049 mmol) was
dissolved in MeCN (0.5 mL) in a 4-dram vial to obtain a yellow
solution. To this was added dropwise a solution of CNC6H3Me2
(6.0 mg, 0.046 mmol) in MeCN (0.25 mL), and the mixture was
placed in the freezer for 1 h. The mixture was then transferred to
the top of an alumina I column (0.5 ꢀ 5 cm), the column was
eluted with 4:1 pentane/Et2O, and the dark orange band that
developed was collected. The solvent was removed from the
eluate in vacuo, and the residue was redissolved in a minimum
amount of Et2O. The Et2O solution was stored overnight at
-30 °C to induce the deposition of 4b as irregularly shaped red
crystals (19.0 mg, 79% yield).
Preparation of Cp*W(NO)(CH2C6H5)(η2-CH3CH2CHCH-
CdNC4H9) (6b). A sample of 2 (19.0 mg, 0.038 mmol) was
dissolved in Et2O (1 mL) and THF (5 mL) in a 4-dram vial to
obtain an orange solution. To this solution was added a solution
of C4H9NC (11.0 mg, 0.133 mmol) in Et2O (1 mL). After 20 h,
the final orange solution was transferred to the top of an
alumina I column (0.5 ꢀ 6 cm). The column was eluted with
Et2O, and the yellow band that developed was collected. The
solvent was removed from the eluate in vacuo, to obtain 6b as a
viscous red oil (14.0 mg, 74% yield).
1
IR: νNO 1548 cm-1. H NMR (400 MHz, C6D6): δ 0.79 (m
Anal. Calcd for C27H42N2OSiW: C, 52.09; H, 6.80; N, 4.50.
Found: C, 52.16; H, 6.78; N, 4.48. IR: νNO 1554 cm-1. 1H NMR
(400 MHz, C6D6): δ -0.30 (d, 2JHH=13.5, 1H, CH2SiMe3), 0.21
(d, 2JHH=13.5, 1H, CH2SiMe3), 0.35 (s, 9H, CH2SiMe3), 0.73 (t,
3JHH=14.9, 3H, CH2CH3), 1.79 (m, 2H, CH2CH3), 1.81 (s, 15H,
C5Me5), 2.05 (s, 6H, aryl CH3), 6.30 (d, 3JHH=15.5, 1H, NCCH),
6.84 (m, 3JHH=15.3, 6.9, 6.5, 1H, CHCH), 6.9-6.95 (m, 3H, aryl
H). 13C{1H} NMR (150 MHz, C6D6): δ 2.9 (CH2SiMe3), 3.8
(CH2SiMe3), 10.8 (C5Me5), 12.8 (CH2CH3), 19.2 (aryl CH3),
27.1 (CH2CH3), 108.5 (C5Me5), 122.3 (CCH), 127.1 (Ar C),
130.0 (Ar C), 131.4 (Ar C), 132.3 (Ar C), 138.4 (Ar C), 156.6
(CHCH), 214.8 (CNCH). MS (LREI, m/z, probe temperature
100 °C): 622 [Pþ, 184W].
overlapping, 6H, butyl CH3 and CHCH2CH3), 1.07 (m, 2H, butyl
CH2), 1.29 (m, 2H, butyl CH2), 1.72 (s, 15H, C5Me5), 1.88 (t,
2
3JHH =7.0, 2H, CHCH2CH3), 2.71 (d, JHH =10.6, 1H, benzyl
CH2), 2.94 (d, 2JHH=10.6, benzyl CH2), 2.96 (m overlapping, 2H,
NCH2CH2), 6.36 (d, JHH=14.9, 1H, NCCH), 6.82 (dt, JHH=
3
3
15.2, 6.5, 1H, CH2CHCH), 6.95 (t, 3JHH=7.2, 1H, para aryl CH),
3
3
7.25 (t, JHH=7.4, 2H, meta aryl CH), 7.83 (d, JHH=7.4, 2H,
ortho aryl CH). 13C{1H} NMR (150 MHz, C6D6): δ 10.4 (C5Me5),
12.7 (MeCH2CH), 14.3 (MeCH2), 21.1 (MeCH2CH2), 27.1
(MeCH2CH), 32.3 (CH2CH2), 32.8 (CH2C6H5), 44.2 (NCH2),
108.1 (C5Me5), 123.0 (CHCHCN), 128.3 (Ar C), 128.7 (Ar C),
129.8 (Ar C), 154.7 (Ar (i) C), 157.8 (CHCN), 208.1 (CN). MS
(LREI, m/z, probe temperature 100 °C): 578 [Pþ, 184W]. MS
(HREI, m/z, probe temperature 100 °C): Pþ calcd for
C26H38N2OW 578.24910, found 578.24937.
Preparation of Cp*W(NO)(CH2C6H5)(η2-CH3CHCHCH2-
CdNC6H3Me2) (5a). A sample of 2 (19.0 mg, 0.039 mmol)
was dissolved in THF (2 mL) in a 4-dram vial to obtain an
orange solution. To this solution was added dropwise a solution
of CNC6H3Me2 (16.0 mg, 0.124 mmol) in THF (1 mL), and the
mixture was left to sit for 20 h. The solvent was removed from
the red-orange solution in vacuo, and the residue was recrys-
tallized from Et2O at -30 °C to obtain 5a as irregularly shaped,
orange-brown crystals (15.0 mg, 79% yield).
Preparation of Cp*(W)(NO)(C(O)Me)(η3-CH2CHCHMe)
(7). A sample of 1 (97.0 mg, 0.198 mmol) was dissolved in C6H6
(6 mL) in a Schlenk tube. The yellow solution was cannulated into
a stainless steel pressure vessel containing additional C6H6 (12
mL). The vessel was pressurized with 1000 psig of CO gas, and the
solution was stirred for 72 h. The pressure was then released, and
the solution was transferred by pipet to a Schlenk tube. The
solvent was removed in vacuo, the yellow residue was dissolved in
pentane, and this solution was transferred to the top of an alumina
I column (2 ꢀ 5 cm). The column was eluted with 4:1 pentane/
Et2O, and the yellow band that developed was collected. The
volume of the eluate was reduced in vacuo, and the concentrated
solution was stored at -30 °C overnight to induce the deposition
of 7 as yellow prisms (51 mg, 53% yield).
IR: νNO 1560 cm-1. 1H NMR (400 MHz, C6D6): δ 1.71 (s, 3H,
aryl Me), 1.77 (s, 3H, aryl Me), 1.86 (d, 3JHH=9.0, 3H, MeCH)
2.05 (s, 15H, C5Me5), 2.41 (d, 2JHH=10.6, 1H, benzyl CH2), 2.69
(d, 2JHH=10.6, 1H, benzyl CH2), 2.78 (dd, 2JHH=17.8, 6.5, 1H,
NCCH2), 3.33 (dd, 2JHH=18.0, 6.3, 1H, NCCH2), 5.23 (m, 1H,
MeCH), 5.38 (m, 1H, MeCHCH), 6.95-7.35 (m, 8H, aryl CH).
13C{1H} NMR (150 MHz, C6D6): δ 10.8 (C5Me5), 18.4 (Me),
18.6 (Me), 19.2 (Me), 36.0 (CH2C6H5), 110.0 (C5Me5), 122.3
(CH2CH), 126.4 (Ar C), 127.4 (Ar C), 127.8 (Ar C), 128.7 (Ar C),
130.0 (Ar C), 130.6 (Ar C), 136.2 (CHMe), 153.0 (Ar (i) C), 221.4
(NC). MS (LREI, m/z, probe temperature 100 °C): 626 [Pþ,
184W]. MS (HREI, m/z, probe temperature 120 °C): Pþ calcd for
C30H38N2OW 626.24937, found 626.24936.
1
IR: νNO 1594 cm-1, νCO 1615 cm-1. H NMR (400 MHz,
C6D6): δ 1.28 (m obscured, 1H, allyl CHMe), 1.63 (s, 15H,
3
C5Me5), 1.65 (d obscured, 2H, allyl CH2), 1.91 (d, JHH=5.5,
3H, CHMe), 2.50 (s, 3H, C(O)Me), 4.57 (ddd, 3JHH=13.8, 9.9,
7.2, 1H, allyl CH). 13C{1H} NMR (150 MHz, C6D6): δ 10.3
(C5Me5), 17.9 (allyl Me), 46.4 (C(O)Me), 61.1 (MeCHCH), 66.1
(CH2CH), 108.7 (C5Me5), 111.1 (MeCHCH), 258.6 (C(O)Me).
MS (LREI, m/z, probe temperature 100 °C); 447 [Pþ, 184W].
Preparation of Cp*(W)(NO)(C(O)CH2CMe3)(η3-CH2CHC-
HMe) (8). In a glovebox, a sample of Cp*(W)(NO)(CH2CMe3)-
(η3-CH2CHCHMe)6 (65.0 mg, 0.137 mmol) was dissolved in
pentane (6 mL) in a 4-dram vial. The orange solution was
transferred to a stainless steel pressure vessel. The vessel was
pressurized with 850 psig of CO gas, and the solution was stirred
for 20 h. The pressure was then released, the solvent was
removed in vacuo, and the vessel was brought into the glovebox.
The yellow residue was dissolved in pentane and transferred to
the top of a Celite column (2 ꢀ 3 cm). The column was eluted
with pentane, and the orange band that developed was collected.
The eluate was taken to dryness in vacuo, and the residue was
redissolved into a minimal amount of pentane. Slow evaporation
Preparation of Cp*W(NO)(CH2C6H5)(η2-CH3CH2CHCH-
CdNC6H3Me2) (5b). A sample of 2 (25.0 mg, 0.051 mmol)
was dissolved in Et2O (5 mL) in a 4-dram vial to obtain an
orange solution. To this solution was added dropwise a solution
of CNC6H3Me2 (8.0 mg, 0.062 mmol) in Et2O (1 mL). After
20 h, the final red solution was transferred to the top of an
alumina I column (0.5 ꢀ 5 cm). The column was eluted with
Et2O, and the red band that developed was collected. The
solvent was removed from the eluate in vacuo, and the residue
was recrystallized from Et2O at -30 °C to obtain 5b as plate-like
red crystals (18.0 mg, 72% yield).
1
IR: νNO 1560 cm-1. H NMR (400 MHz, C6D6): δ 0.87 (t,
3JHH = 7.4, 3H, MeCH2CH), 1.57 (s, 3H, aryl Me), 1.92 (m
overlapping, 2H, MeCH2CH), 1.99 (s, 15H, C5Me5), 2.09 (s, 3H,
aryl Me), 2.75 (d, 2JHH=10.2, 1H, benzyl CH2), 2.98 (d, 2JHH=10.2,

Article
Organometallics, Vol. 28, No. 15, 2009 4489
Table 1. X-ray Crystallographic Data for Complexes 3, 4a, 4b, and 8-10
3
4a
4b
Crystal Data
empirical formula
cryst habit, color
cryst size (mm)
cryst syst
C
23H22
C27H42N2OSiW
irregular, yellow
0.15 ꢀ 0.125 ꢀ 0.075
triclinic
C27H42N2OSiW
prism, red-orange
0.50 ꢀ 0.40 ꢀ 0.25
monoclinic
P21/n
2821.1(4)
9.7644(8)
16.7802(14)
17.2285(15)
90
91.998(4)
90
4
1.466
4.157
1256
needle, yellow
0.45 ꢀ 0.30 ꢀ 0.20
monoclinic
P21/c
1672.13(17)
16.0109(10)
14.4336(9)
7.2497(4)
90
93.563(2)
90
4
1.185
space group
P1
3
volume (A )
˚
1338.0(4)
9.8708(16)
11.1838(17)
12.928(2)
84.215(8)
87.804(9)
70.445(8)
2
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
Z
density(calcd) (Mg/m3)
1.545
4.382
628
absorp coeff (mm-1
F000
)
0.067
640
Data Collection and Refinement
measd reflns: total
9091
3260
35 982
6344
54 722
8712
measd reflns: unique
final R indicesa
R1 = 0.0404, wR2 = 0.1061
1.017
0.223 and -0.189
R1 = 0.0421, wR2 = 0.1211
1.055
1.962 and -2.460
R1 = 0.0181, wR2 = 0.0419
1.045
0.950 and -0.920
goodness-of-fit on F2b
-3
˚
A
largest diff peak and hole (e-
)
8
9
10
Crystal Data
empirical formula
cryst habit, color
cryst size (mm)
cryst syst
C20H33NO2W
irregular, yellow
0.6 ꢀ 0.4 ꢀ 0.25
monoclinic
P21/n
4349.7(14)
18.610(3)
8.8162(15)
26.648(5)
90
C25H35NO2W
block, yellow
0.4 ꢀ 0.35 ꢀ 0.12
monoclinic
P21/c
2377.4(17)
21.981(5)
11.708(5)
9.402(5)
90
C20H33NO2W
prism, yellow
0.50 ꢀ 0.40 ꢀ 0.20
orthorhombic
Pbca
4034.5(5)
9.2523(8)
17.8946(13)
24.3680(17)
90
space group
3
volume (A )
˚
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
95.810(8)
90
100.724(5)
90
90
90
Z
8
1.537
5.322
2000
4
1.580
4.878
1128
8
1.657
5.738
2000
density(calcd) (Mg/m3)
absorp coeff (mm-1
F000
)
Data Collection and Refinement
measd reflns: total
84 036
9994
5534
5534
25 939
4847
measd reflns: unique
final R indicesa
R1 = 0.0297, wR2 = 0.0864
1.109
2.500 and -0.829
R1 =0.0353, wR2 = 0.0942
1.282
1.957 and -2.552
R1 = 0.0264, wR2 = 0.0574
1.043
2.143 and -0.810
goodness-of-fit on F2b
largest diff peak and hole (e A
-3
˚
)
P
P
P
P
P
a R1 on F = |(|Fo| - |Fc|)|/ |Fo| (I > 2σ(I)); wR2 = [( (Fo2 - Fc2)2)/ w(Fo2)2]1/2 (all data); w = [ σ2F2o ]-1
.
b GOF = [ (w(|Fo| - |Fc|)2)/degrees of
freedom ]1/2
.
of the pentane solution maintained at -30 °C overnight induced
deposition of 8 as yellow hedgehog-like crystals (32 mg, 49%).
Anal. Calcd for C20H33NO2W: C, 47.73; H, 6.61; N, 2.78.
Found: C, 47.78; H, 6.59; N, 2.80. IR (cm-1): 1598 (s, νNO), 1626
(s, νCO). MS (LREI, m/z, probe temperature 100 °C): 503 [Pþ,
184W]. 1H NMR (400 MHz, C6D6): δ 1.21 (s, 9H, CH2CMe3), 1.5
(d, 3JHH=5.85, 1H, allyl CHMe), 1.64 (s, 15H, C5Me5), 1.89 (d,
3JHH=5.55, 3H, allyl CHMe), 2.57 (d, 3JHH=12.6, 1H, allyl CH2),
transferred to a stainless steel pressure vessel. The vessel was
pressurized with 850 psig of CO gas, and the solution was stirred
for 20 h. The pressure was then released, the solvent was
removed in vacuo, and the vessel was taken into the glovebox.
The yellow residue was dissolved in diethyl ether and transferred
to the top of a Celite column (2 ꢀ 5 cm). The column was eluted
with diethyl ether, and the yellow band that developed was
collected. The eluate was taken to dryness in vacuo, and the
residue was redissolved in a minimal amount of diethyl ether.
The ether solution was stored at -30 °C overnight to induce
deposition of 9 as square yellow crystals (25 mg, 81%).
Anal. Calcd for C25H35NO2W: C, 53.11; H, 6.24; N, 2.48. Found:
C, 52.73; H, 6.19; N, 2.45. IR (cm-1): 1591 (s, νNO), 1637 (s, νC1O).
MS (LREI, m/z, probe temperature 100 °C): 565 [Pþ, 184W]. H
NMR (400 MHz, C6D6): δ 1.22 (s, 9H, CH2CMe3), 1.54 (s, 15H,
C5Me5), 1.60 (s, 2H, C(O)CH2), 2.42 (d, 1H, 3JHH=10.5, PhCH),
3.25 (m, 2H, allyl CH2), 5.45 (ddd, 1H, 3JHH=12.9, 10.9, 7.2, allyl
CHCH2), 7.03 (t, 1H, aryl CH), 7.23 (t, 2H, aryl CH), 7.30 (d, 2H,
aryl CH). 13C{1H} NMR (150 MHz, C6D6): δ 10.2 (C5Me5), 30.1
(CH2CMe3), 32.1 (CH2CMe3), 67.1 (allyl CH2), 71.5 (allyl CHPh),
2
2
2.74 (d, JHH =16.6, 1H, CH2CMe3), 2.89 (d, JHH =16.6, 1H,
CH2CMe3), 3.36 (d, 3JHH=18.1, 1H, allyl CH2), 4.65 (ddd, 3JHH
=
13.5, 10.0, 7.16, 1H, allyl CH), δ (secondary isomer) selected signals
1.23 (s, 9H, CH2CMe3), 1.58 (s, 15H, C5Me5). 13C{1H} NMR (150
MHz, C6D6): δ 10.3 (C5Me5), 17.8 (allyl CHMe), 30.3 (CMe3), 32.4
(CMe3), 61.6 (allyl CHMe), 72.5 (CH2CMe3), 75.4 (allyl CH2),
108.6 (C5Me5), 111.4 (allyl CH), 263.0 (C(O)), δ (secondary isomer)
selected signals 10.2 (C5Me5), 30.5 (CMe3), 107.2 (C5Me5).
Preparation of Cp*(W)(NO)(C(O)CH2CMe3)(η3-CH2CHC-
HPh) (9). In a glovebox, a sample of Cp*(W)(NO)(CH2CMe3)-
(η3-CH2CHCHPh)6 (31.0 mg, 0.058 mmol) was dissolved in
diethyl ether (3 mL) in a 4-dram vial. The yellow solution was

4490 Organometallics, Vol. 28, No. 15, 2009
Semproni et al.
75.0 (C(O)CH2), 108.8 (C5Me5), 109.8 (allyl CH), 126.4 (aryl C),
127.8 (aryl C), 129.0 (aryl C), 141.7 (ipso C), 261.6 (C(O)CH2).
Preparation of Cp*(W)(NO)(C(O)CH2CMe3)(η3-CH2CMe-
CH2) (10). This compound was prepared from Cp*(W)(NO)-
(CH2CMe3)(η3-CH2CMeCH2)6 and CO in a manner identical
to that described in the preceding paragraph for 9. The yellow
eluate from the Celite column was taken to dryness in vacuo, and
the residue was redissolved in a minimal amount of a 1:1
pentane/diethyl ether mixture. Slow evaporation of the solution
stored at -30 °C overnight induced deposition of 10 as square
yellow crystals (31 mg, 78%).
Anal. Calcd for C20H33NO2W: C, 47.73; H, 6.61; N, 2.78.
Found: C, 47.35; H, 6.48; N, 2.78. IR (cm-1): 1596 (s, νNO), 1634
(s, νCO). MS (LREI, m/z, probe temperature 100 °C): 503 [Pþ,
184W]. 1H NMR (400 MHz, C6D6): δ 0.97 (br s, 1H, allyl CH2),
1.19 (s, 9H, CH2CMe3), 1.66 (s, 15H, C5Me5), 2.28 (s, 3H, allyl
CH3), 2.57 (s, 1H, allyl CH2), 2.85 (d, 1H, CH2CMe3), 3.06 (d,
1H, CH2CMe3), 3.26 (br s, 2H, allyl CH2). 13C{1H} NMR (150
MHz, C6D6): δ 10.6 (C5Me5), 23.0 (allyl Me), 30.3 (CH2CMe3),
32.2 (CH2CMe3), 51.0 (allyl CH2), 70.8 (allyl CH2), 77.5 (C(O)-
CH2), 108.6 (C5Me5), 128.2 (obscured, CMe), 264.3 (C(O)CH2).
Preparation of Cp*(W)(NO)(C(O)CH2CMe3)(η3-CH2CH-
CH2) (11). This complex was prepared from Cp*(W)(NO)-
(CH2CMe3)(η3-CH2CHCH2)6 and CO and was isolated in a
manner identical to that described for 9 above. The final ether
solution was stored at -30 °C overnight to induce deposition of
11 as square yellow crystals (42 mg, 86%).
of full-matrix least-squares analysis was based on 6344 observed
reflections and 318 variable parameters.
Data for 4b were collected to a maximum 2θ value of 61.4° in
0.5° oscillations. The structure was solved by direct methods25 and
expanded using Fourier techniques.26 All non-hydrogen atoms
were refined anisotropically. Hydrogens H3 and H4 were refined
isotropically, and all other hydrogen atoms were included in fixed
positions. The final cycle of full-matrix least-squares analysis was
based on 8712 observed reflections and 308 variable parameters.
Data for 8 were collected to a maximum 2θ value of 55.2° in
0.5° oscillations. The structure was solved by direct methods25
and expanded using Fourier techniques.26 The Me3Si fragment
of one molecule in the asymmetric unit was disordered and was
modeled in two orientations (one with 80% occupancy and one
with 20% occupancy). The carbons of the 20% fragment were
refined isotropically. All other non-hydrogen atoms were re-
fined anisotropically, and all hydrogen atoms were included in
fixed positions. The SQUEEZE program27 was used to remove
one-half of a molecule of disordered diethyl ether solvent during
structure solution. The final cycle of full-matrix least-squares
analysis was based on 9994 observed reflections and 467 variable
parameters.
Data for 9 were collected to a maximum 2θ value of 55.4° in
0.5° oscillations. The structure was solved by direct methods25
and expanded using Fourier techniques.26 The crystal was
a two-component twin that was separated into its components
using Cell_Now,28 SAINTPLUS,29 and TWINABS.30 All
non-hydrogen atoms were refined anisotropically, and all hy-
drogen atoms were included in fixed positions. The final cycle of
full-matrix least-squares analysis was based on 5534 observed
reflections and 270 variable parameters.
Anal. Calcd for C19H31NO2W: C, 46.64; H, 6.39; N, 2.86.
Found: C, 46.46; H, 6.36; N, 2.90. IR (cm-1): 1599 (s, νNO), 1631
(s, νCO). MS (LREI, m/z, probe temperature 100 °C): 489 [Pþ,
184W]. 1H NMR (400 MHz, C6D6): δ 1.22 (s, 9H, CH2CMe3), 1.57
(s, 15H, C5Me5), 2.15 (br s, 2H, CH2CMe3), 2.65 (d, 1H, 2JHH
=
Data for 10 were collected to a maximum 2θ value of 56.0° in
0.5° oscillations. The structure was solved by direct methods25
and expanded using Fourier techniques.26 All non-hydrogen
atoms were refined anisotropically, and all hydrogen atoms
were included in fixed positions. The final cycle of full-matrix
least-squares analysis was based on 4847 observed reflections
and 242 variable parameters.
13.3, allyl CH2), 2.96 (d, 1H, 2JHH=14.1, allyl CH2), 3.09 (br s, 1H,
allyl CH2), 3.49 (d, 3JHH=18, allyl CH2), 4.91 (br s, 1H, allyl CH).
13C{1H} NMR (150 MHz, C6D6): δ 10.2 (C5Me5), 23.1
(CH2CMe3), 30.2 (CH2CMe3), 32.1 (CH2CMe3), 50.9 (allyl CH2),
77.9 (allyl CH2), 101.4 (allyl CH), 107.3 (C5Me5), 268.0 (WC(O)).
Other Attempted Reactions of 1. Treatment of 1 with the
following gaseous reagents at the noted pressures resulted in no
reaction: dihydrogen (1 atm), dioxygen (1 atm), nitric oxide
(1 atm), and carbon monoxide (1 and 6 atm).
For each structure neutral-atom scattering factors were taken
from Cromer and Waber.31 Anomalous dispersion effects were
32
included in Fcalc
;
the values for Δf 0 and Δf 00 were those of
X-ray Crystallography. Datacollectionfor eachcompoundwas
carried out at -100 ( 1 °C on a Bruker X8 APEX diffractometer,
using graphite-monochromated Mo KR radiation.
Creagh and McAuley.33 The values for mass attenuation coeffi-
cients are those of Creagh and Hubbell.34 All calculations were
performed using Shelxl-97.35 X-ray crystallographic data for the
six structures are presented in Table 1 and in the cif files.
Data for 3 were collected to a maximum 2θ value of 54.8° in
0.5° oscillations. The structure was solved by direct methods25
and expanded using Fourier techniques.26 Due to equipment
failure, only a partial data set was collected (∼80%). Never-
theless, the connectivity and R values are sufficiently good to
merit the inclusion of this crystallographic analysis. All non-
hydrogen atoms were refined anisotropically. Hydrogens H2
and H3 were refined isotropically, and all other hydrogen atoms
were included in fixed positions. The final cycle of full-matrix
least-squares analysis was based on 3260 observed reflections
and 217 variable parameters.
Acknowledgment. We are grateful to Dr. Chris Wallis
for assistance with the high-pressure CO reactions, and
we acknowledge NSERC Canada for funding.
Supporting Information Available: CIF files providing full
details of crystallographic analyses of complexes 3, 4a, 4b, 8, 9,
and 10. This material is available free of charge via the Internet at
http://pubs.acs.org.
Data for 4a were collected to a maximum 2θ value of 56.4° in
0.5° oscillations. The structure was solved by direct methods25
and expanded using Fourier techniques.26 The C1-C2-C3
fragment was disordered in two orientations, modeled as two
parts (A and B) each with 50% occupancy. As a result of their
proximity, C3a and C3b were refined isotropically, while all
other non-hydrogen atoms were refined anisotropically. All
hydrogen atoms were included in fixed positions. The final cycle
(27) SQUEEZE: Sluis, P. v. d.; Spek, A. L. Acta Crystallogr., Sect. A
1990, 46, 194.
(28) Cell_Now 2008/2; Bruker AXS Inc.: Madison, WI.
(29) SAINTPLUS, Version 7.53A; Bruker AXS Inc.: Madison, WI,
1997-2008.
(30) TWINABS, V2008/2; Bruker AXS Inc.: Madison, WI, 2007.
(31) Cromer, D. T.; Waber, J. T. International Tables for X-ray
Crystallography; Kynoch Press: Birmingham, 1974; Vol. IV.
(32) Ibers, J. A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781–782.
(33) Creagh, D. C.; McAuley, W. J. International Tables of X-ray
Crystallography; Kluwer Academic Publishers: Boston, 1992; Vol. C.
(34) Creagh, D. C.; Hubbell, J. H. International Tables for X-ray
Crystallography; Kluwer Academic Publishers: Boston, 1992; Vol. C.
(25) SIR92: Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi,
A. J. Appl. Crystallogr. 1993, 26, 343.
(26) PATTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman,
W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J. M. M.; Smykalla, C.
University of Nijmegen, The Netherlands, 1992.
€
(35) Sheldrick, G. M. SHELXL97; University of Gottingen: Germany,
1997.