Alcohol complexes of tungsten prepared by ionic hydrogenations of ketones

Article abstract of DOI:10.1021/om010222l

Ionic hydrogenation of acetone by Cp(CO)₃WH and HOTf (OTf = OSO₂CF₃) gives the 2-propanol complex [Cp(CO)₃W(HOⁱPr)]⁺OTf^-. ¹H NMR data suggest O-H?O hydrogen bonding between the alcohol OH and an oxygen of the triflate anion in solution, and a crystal structure of this complex shows that hydrogen bonding also exists in the solid state. The short O?O distance of 2.63(1) ? indicates a strong hydrogen bond. Hydrogenation of other ketones and aldehydes gives related [Cp(CO)₃W(alcohol)]⁺OTf complexes. Aldehydes are selectively hydrogenated over ketones, and alkyl ketones are selectively hydrogenated over aromatic ketones. Hydrogenation of acetophenone gives ethylbenzene, with no intermediate tungsten complexes being observed. Reaction of 1-phenyl-1,3-butanedione with Cp(CO)₃WH and HOTf gave {Cp(CO)₃W[CH₃CH(OH)CH₂C(=O)Ph]}⁺ OTf^-, the structure of which was determined by X-ray diffraction. The alcohol complexes [Cp(CO)₃W(alcohol)]⁺OTf^- decompose in solution to give free alcohols and Cp(CO)₃WOTf. The cationic dihydride [Cp(CO)₂(PMe₃-W(H)₂]⁺OTf^- hydrogenates aldehydes and ketones; in these reactions a metal hydride serves as both the proton and hydride donor.

Full text of DOI:10.1021/om010222l

Organometallics 2001, 20, 3337-3346
3337
Alcoh ol Com p lexes of Tu n gsten P r ep a r ed by Ion ic
Hyd r ogen a tion s of Keton es
J eong-Sup Song,† David J . Szalda,‡ and R. Morris Bullock*
Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000
Received March 21, 2001
Ionic hydrogenation of acetone by Cp(CO)3WH and HOTf (OTf ) OSO2CF3) gives the
1
2-propanol complex [Cp(CO)3W(HOiPr)]+OTf-. H NMR data suggest O-H‚‚‚O hydrogen
bonding between the alcohol OH and an oxygen of the triflate anion in solution, and a crystal
structure of this complex shows that hydrogen bonding also exists in the solid state. The
short O‚‚‚O distance of 2.63(1) Å indicates a strong hydrogen bond. Hydrogenation of other
ketones and aldehydes gives related [Cp(CO)3W(alcohol)]+OTf- complexes. Aldehydes are
selectively hydrogenated over ketones, and alkyl ketones are selectively hydrogenated over
aromatic ketones. Hydrogenation of acetophenone gives ethylbenzene, with no intermediate
tungsten complexes being observed. Reaction of 1-phenyl-1,3-butanedione with Cp(CO)3WH
-
and HOTf gave {Cp(CO)3W[CH3CH(OH)CH2C(dO)Ph]}+OTf , the structure of which was
determined by X-ray diffraction. The alcohol complexes [Cp(CO)3W(alcohol)]+OTf- decompose
in solution to give free alcohols and Cp(CO)3WOTf. The cationic dihydride [Cp(CO)2(PMe3)-
W(H)2]+OTf- hydrogenates aldehydes and ketones; in these reactions a metal hydride serves
as both the proton and hydride donor.
Alcohol ligands on low-valent transition metals are
involved in several homogeneously catalyzed reactions.1
Facile displacement of the methanol ligands of [Rh-
(diphosphine)(MeOH)2]+ provides a site for coordination
of the unsaturated substrate in the catalytic cycle for
hydrogenation of olefins.2 Iridium complexes with al-
cohol ligands, such as [IrH2(PPh3)2(EtOH)2]+, are used
in the homogeneous catalysis of olefin hydrogenation3
and the catalytic alcoholysis of hydrosilanes.4 Alcohol
complexes are proposed as intermediates in the catalytic
hydrogenation of ketones catalyzed by Rh complexes.5
Hydrogenations of ketones can proceed through ionic
pathways. Hydride transfer from a metal hydride to a
protonated ketone appears to be involved in several
previously reported examples of stoichiometric hydro-
genation of CdO bonds. In most of these cases the
product is a free alcohol rather than a metal complex
with an alcohol ligand. Kinetic studies of the hydroge-
nation of acetone by [Ru(bpy)2(CO)H]+ in aqueous
solution support preequilibrium protonation of the
acetone followed by hydride transfer from the metal.6
Darensbourg and co-workers reported7 hydrogenation
of aldehydes and ketones by acetic acid and a series of
anionic metal hydrides such as HCr(CO)5-. Aldehydes
are selectively reduced in the presence of ketones8 using
acetic acid and the bridging anionic hydride complex
[Mo2(CO)10(µ-H)]+. The molybdenum dihydride complex
Cp2MoH2 can be used with acetic acid to hydrogenate
ketones.9 Bakhmutov and co-workers recently reported
the characterization by low-temperature NMR of alcohol
complexes of rhenium formed by ionic hydrogenation of
i
ketones by ReH2(CO)(NO)(PR3)2 (R ) Pr, CH3, OiPr)
and CF3CO2H.10 In a few cases there is evidence for hy-
drogenation of ketones in which both the proton and the
hydride are supplied from a metal. The tantalum dihy-
dride [Cp2(CO)TaH2]+ reacts with acetone to produce a
2-propanol complex,11 [Cp2(CO)Ta(HOiPr)]+. Hydroge-
nation of acetone by the η2-dihydrogen complex [(NH3)5-
Os(η2-H2)]3+ may proceed through an ionic mechanism.12
Our research on ionic hydrogenations has shown that
unsaturated organic substrates can be hydrogenated
using a strong acid (typically CF3SO3H, abbreviated as
HOTf) as a proton source and a metal hydride as a
hydride donor. The CdC bonds of tetrasubstituted, tri-
substituted, and 1,1-disubstituted alkenes are hydro-
genated at -50 °C using HOTf and metal carbonyl
† Present address: Department of Chemistry, Sun Moon University,
Asan City, Chungnam, South Korea, 336-840.
‡ Research Collaborator at Brookhaven National Laboratory. Per-
manent address: Department of Natural Sciences, Baruch College,
New York, NY 10010.
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neous Hydrogenation; Kluwer Academic Publishers: Boston, 1994.
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1754.
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C. A.; Quirk, J . M.; Morris, G. E. J . Am. Chem. Soc. 1982, 104, 6994-
7001.
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2535.
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Am. Chem. Soc. 1985, 107, 2428-2434.
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1475.
(9) (a) Ito, T.; Koga, M.; Kurishima, S.; Natori, M.; Sekizuka, N.;
Yoshioka, K. J . Chem. Soc., Chem. Commun. 1990, 988-989. (b)
Minato, M.; Fujiwara, Y.; Koga, M.; Matsumoto, N.; Kurishima, S.;
Natori, M.; Sekizuka, N.; Yoshioka, K.; Ito, T. J . Organomet. Chem.
1998, 569, 139-145.
(10) Bakhmutov, V. I.; Vorontsov, E. V.; Antonov, D. Y. Inorg. Chim.
Acta 1998, 278, 122-126.
(5) Schrock, R. R.; Osborn, J . A. J . Chem. Soc., Chem. Commun.
1970, 567-568.
(6) Geraty, S. M.; Harkin, P.; Vos, J . G. Inorg. Chim. Acta 1987,
131, 217-220.
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nometallics 1986, 5, 1863-1866.
(12) Harman, W. D.; Taube, H. J . Am. Chem. Soc. 1990, 112, 2261-
2263.
10.1021/om010222l CCC: $20.00 © 2001 American Chemical Society
Publication on Web 06/21/2001

3338 Organometallics, Vol. 20, No. 15, 2001
Song et al.
hydrides.13 The CtC bonds of some alkynes can also
be hydrogenated using HOTf and Cp(CO)3WH; such
cases involve
a double hydrogenation, converting
PhCtCH to PhCH2CH3, for example.14 In this paper we
report the synthesis and characterization of a series of
alcohol complexes of tungsten. The alcohol ligand is
produced in these reactions through ionic hydrogenation
of an aldehyde or ketone.15 In contrast, most previously
reported examples where alcohol complexes were pre-
pared and isolated involved adding an intact alcohol
molecule to a metal complex with a weakly bound
ligand. Examples include Beck’s synthesis of alcohol
complexes of tungsten16 and ruthenium17 by displace-
ment of weakly coordinating BF4 or SbF6 ligands and
the synthesis of a series of chiral rhenium alcohol
complexes by Gladysz and co-workers through displace-
ment of weakly bound CH2Cl2 ligands.18
Resu lts
F igu r e 1. Drawing of [Cp(CO)3W(HOiPr)]+OTf-. The
thermal ellipsoids are at the 50% probability level, and the
hydrogen atoms (except H4) are omitted.
Syn th esis a n d Ch a r a cter iza tion of [Cp (CO)3W-
(a lcoh ol)]+OTf- Com p lexes. Addition of triflic acid
(HOTf) to a CH2Cl2 solution of Cp(CO)3WH and ace-
tone produces the 2-propanol complex [Cp(CO)3W-
(HOiPr)]+OTf-, which was isolated as a dark red mi-
crocrystalline solid in 78% yield (eq 1). The OH of the
bound 2-propanol ligand appears as a doublet (J ) 7.4
Ionic hydrogenations of propionaldehyde, 2-adaman-
tanone, and cyclohexanone gave tungsten alcohol com-
plexes that were also isolated and fully characterized
1
1
by H NMR, 13C NMR, IR, and elemental analysis (eqs
Hz) at δ 7.34 in the H NMR spectrum in CD2Cl2. This
1
2-4). H NMR chemical shifts of the OH resonances
OH resonance for the bound 2-propanol ligand appears
at least 5 ppm downfield from that of free 2-propanol,
indicating substantial hydrogen bonding of the alcohol.
(The OH resonance of free alcohols varies somewhat
depending on concentration, presence of water, etc.) The
structure of [Cp(CO)3W(HOiPr)]+OTf- was determined
by single-crystal X-ray diffraction; Figure 1 shows the
O-H‚‚‚O hydrogen bonding observed in the solid state.
Table 1 provides data collection and refinement details,
and Table 2 lists selected bond distances and angles.
The short O‚‚‚O distance of 2.63(1) Å is indicative of a
strong hydrogen bond.
were in the range δ 6.94-7.75 for these compounds,
indicating hydrogen bonding to OTf in all of these cases.
Hydrogenations of 2-butanone, pivaldehyde [tBuC-
(dO)H], and 4-phenyl-2-butanone by Cp(CO)3WH and
HOTf were carried out in NMR tubes. The [Cp(CO)3W-
(alcohol)]+OTf- products from these reactions were
characterized by 1H NMR and appear entirely analogous
to the examples that were fully characterized; details
are provided in the Experimental Section. Even though
1,3,5-trioxane, [(CH2O)3], has little solubility in CD2Cl2,
it reacted with Cp(CO)3WH and HOTf to give the
methanol complex [Cp(CO)3W(HOCH3)]+OTf-. Appar-
ently ring-opening occurs in the presence of the acid,
resulting in the chemical equivalent of hydrogenation
of formaldehyde to methanol.
(13) Bullock, R. M.; Song, J .-S. J . Am. Chem. Soc. 1994, 116, 8602-
8612.
(14) Luan, L.; Song, J .-S.; Bullock, R. M. J . Org. Chem. 1995, 60,
7170-7176.
(15) Some of these results were published in a communication:
Song, J .-S.; Szalda, D. J .; Bullock, R. M.; Lawrie, C. J . C.; Rodkin, M.
A.; Norton, J . R. Angew. Chem., Int. Ed. Engl. 1992, 31, 1233-1235.
(16) Su¨nkel, K.; Urban, G.; Beck, W. J . Organomet. Chem. 1985,
290, 231-240.
(17) Milke, J .; Missling, C.; Su¨nkel, K.; Beck, W. J . Organomet.
Chem. 1993, 445, 219-227.
(18) Agbossou, S. K.; Smith, W. W.; Gladysz, J . A. Chem. Ber. 1990,
123, 1293-1299.
When hydrogenation of acetophenone is attempted
with 1 equiv each of Cp(CO)3WH and HOTf, only half

Alcohol Complexes of Tungsten
Organometallics, Vol. 20, No. 15, 2001 3339
Ta ble 1. Cr ysta llogr a p h ic Da ta for
[Cp (CO)3W(HOiP r )]+OTf- a n d
{Cp (CO)3W[CH3CH(OH)CH2C(dO)P h ]}+OTf-
[Cp(CO)3W-
{Cp(CO)3W[CH3CH-
(HOiPr)]+OTf- (OH)CH2C(dO)Ph]}+OTf-
formula
mol wt
space group
a, Å
b, Å
c, Å
C12H13F3O7SW
542.13
P21/n
8.139(1)
20.906(5)
10.516(2)
90.00
113.22(2)
90.00
1644.4(5)
4
2.190
200
Mo KR
0.7215
empirical
4798
C19H17F3O8SW
646.24
P1h
10.391(2)
12.000(2)
8.768(2)
95.68(2)
98.43(2)
96.53(2)
1067.0(4)
2
2.011
200
Mo KR
0.5581
Gaussian
5180
R (deg)
â (deg)
γ (deg)
V, Å3
Z
F(calcd) g cm-3
temp (K)
radiation
µ, cm-1
abs corr
no. of reflns
collected
no. of unique
reflns
F igu r e 2. View of {Cp(CO)3W[CH3CH(OH)CH2C(dO)-
Ph]}+OTf-. The thermal ellipsoids are at the 50% prob-
ability level. The hydrogen atoms are omitted, except for
H49.
4798
4910
2θ limits (deg)
60.0
218
0.0541
0.1389
55.0
290
0.0479
0.1382
<0.001
no. of variables
a
R1 (I>2σ(I))
was assessed. When acetone and pivaldehyde in the
same NMR tube were reacted with Cp(CO)3WH and
HOTf, only the aldehyde was hydrogenated. The for-
mation of the neopentyl alcohol complex {Cp(CO)3W-
[HOCH2C(CH3)3]}+OTf- indicates a strong preference
for hydrogenation of the aldehyde over the ketone. None
of the 2-propanol complex that would have resulted from
hydrogenation of acetone was detected. The 1H NMR
resonance for acetone shifted from δ 2.12 to 2.15,
suggesting that some of the acetone was protonated by
HOTf.
wR2
max. shift/error, 0.001
final cycle
a
2
4
R1 ) ∑|Fo| - |Fc|/∑|Fo|; wR2 ) {∑[w(|Fo | - |Fc2)2]/∑[w|Fo |]}1/2
.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [Cp (CO)3W(HOiP r )]+OTf-
W(1)-C(3)
W(1)-C(1)
W(1)-C(2)
W(1)-O(4)
W-Cpa
1.994(14)
2.012(14)
2.015(15)
2.176(8)
1.99(1)
A similar competition between acetone and acetophe-
none resulted in hydrogenation of the acetone, with no
product from hydrogenation of acetophenone being
detected. This is thought to be due to stabilization of
the protonated acetophenone by the phenyl group,
making it a weaker hydride acceptor. An intramolecular
competition between aliphatic and aromatic ketone
functional groups was carried out, as shown in eq 7. The
C(3)-W(1)-C(1)
C(3)-W(1)-C(2)
C(1)-W(1)-C(2)
C(3)-W(1)-O(4)
C(1)-W(1)-O(4)
C(2)-W(1)-O(4)
110.5(6)
76.8(6)
76.0(5)
83.8(4)
78.6(4)
140.0(5)
a
Cp designates the centroid of the cyclopentadienyl ring.
of the acetophenone is consumed, and ethylbenzene is
produced. The reaction does proceed cleanly to comple-
tion when 2 equiv each of Cp(CO)3WH and HOTf are
used (eq 5), but it proceeds more slowly than hydroge-
nation of aliphatic ketones. No sec-phenethyl alcohol is
observed as an intermediate in these reactions, indicat-
ing that the rate of its conversion to ethylbenzene is
faster than that of acetophenone. Separate experiments
starting with this alcohol verified that it is converted
to ethylbenzene by Cp(CO)3WH and HOTf (eq 6).
1
product of this reaction was fully characterized by H
NMR, 13C NMR, IR, and elemental analysis as well as
a crystal structure. The structure found in the solid
(Figure 2) is similar to that found for the 2-propanol
complex with hydrogen bonding of the OH to the triflate
counterion. Table 1 provides data collection and refine-
ment details, and Table 3 lists selected bond distances
and angles. The O‚‚‚O distance of 2.63(1) Å is indicative
of a strong hydrogen bond; this distance is the same as
that found for [Cp(CO)3W(HOiPr)]+OTf-. This complex
Selectivity of CdO Hyd r ogen a tion . The possibility
of selective hydrogenations by Cp(CO)3WH and HOTf

3340 Organometallics, Vol. 20, No. 15, 2001
Song et al.
Ta ble 3. Selected Bon d Len gth s (Å) a n d
An gles (d eg) for
{Cp (CO)3W[CH3CH(OH)CH2C(dO)P h ]}+OTf-
W-C(2)
W-C(1)
W-C(3)
W-O(49)
W-Cpa
1.978(12)
2.017(12)
2.038(12)
2.169(8)
1.99(1)
C(2)-W-C(1)
C(2)-W-C(3)
C(1)-W-C(3)
C(2)-W-O(49)
C(1)-W-O(49)
C(3)-W-O(49)
75.6(5)
76.6(5)
112.9(5)
140.3(4)
85.5(4)
79.3(4)
a
Cp designates the centroid of the cyclopentadienyl ring.
might have been able to form an intramolecular hydro-
gen bond between the CdO of the aromatic ketone and
the OH of the alcohol. Such a hydrogen bond would form
a six-membered ring that might be expected to be stable.
In the crystal structure, however, hydrogen bonding to
OTf- is found, so this mode of hydrogen bonding is
preferred, at least in the solid. Another diketone that
was hydrogenated was diacetyl, CH3(CdO)2CH3, giving
the alcohol complex {Cp(CO)3W[CH3CH(OH)C(dO)-
CH3]}+OTf-, which was isolated and fully characterized.
We previously found that ether complexes of tungsten
could be isolated from reactions of acetals with Cp-
(CO)3WH and HOTf.19 Two examples were crystallo-
graphically characterized, including one having an
oxygen-bound ether and another in which a vinyl acetal
was converted to a vinyl ether bound to tungsten
through the CdC bond. Results from an NMR tube
reaction of 1,1-dimethoxyacetone with Cp(CO)3WH and
HOTf (eq 8) provided evidence for the formation of an
alcohol complex, indicating selective CdO hydrogena-
tion in the presence of an acetal functionality.
alcohol complexes with triflate counterion also decom-
posed in a similar manner, but the rates of these
reactions were not studied in detail. The alcohol ligand
can be quickly and cleanly displaced by addition of
NEt4Br, resulting in the release of free alcohol and
formation of Cp(CO)3WBr.
-
An Alcoh ol Com p lex of Tu n gsten w ith a BAr ′4
Cou n ter ion . These complexes with triflate counterion
may be compared to a related alcohol complex with a
noncoordinating counterion. Reaction of acetone with
Cp(CO)3WH and [H(OEt2)2]+BAr′4 [Ar′ ) 3,5-bis(tri-
-
-
fluoromethyl)phenyl] gave [Cp(CO)3W(HOiPr)]+BAr′4
,
which was isolated in 69% yield as an analytically pure
1
solid. A notable feature in the H NMR spectrum of this
complex is the appearance of the OH resonance as a
doublet (J ) 7.9 Hz) at δ 2.41. The substantial upfield
shift of this resonance, compared to the OH in the
triflate complex [Cp(CO)3W(HOiPr)]+OTf -, suggests
little or no hydrogen bonding of the OH in the complex
-
with the BAr′4 counterion. This 2-propanol complex
-
with the BAr′4 counterion is much more stable than
[Cp(CO)3W(HOiPr)]+OTf-. A solution of [Cp(CO)3W-
(HOiPr)]+BAr′4 that was left at room temperature for
-
1 day showed only 16% free HOiPr (cf. eq 9 for much
faster decomposition of [Cp(CO)3W(HOiPr)]+OTf-).
Addition of acetone (1 equiv) to a solution of [Cp-
(CO)3W(HOiPr)]+BAr′4 in CD2Cl2 causes a downfield
-
1
shift of the H NMR resonance of the OH doublet to δ
6.74, suggesting that acetone serves as a hydrogen bond
acceptor in an O-H‚‚‚O hydrogen bond. Over the course
of several days, the 2-propanol ligand of [Cp(CO)3W-
(HOiPr)]+BAr′4 is displaced by acetone, giving [Cp-
-
(CO)3W(η1-OdCMe2)]+BAr′4-. After 5 days, about a 1:1
ratio of 2-propanol and acetone complexes were observed
by NMR, but the equilibrium constant was not deter-
mined. This acetone complex, [Cp(CO)3W(η1-OdCMe2)]+-
BAr′4-, was not isolated, but it is closely related to
ketone complexes that were fully characterized.20 We
previously reported the isolation and characterization
of a series of [Cp(CO)3W(η1-ketone)]+ complexes by ionic
hydrogenation of R,â-unsaturated ketones.20
Ion ic Hyd r ogen a tion of Keton es w ith Mo, Mn ,
a n d Re Hyd r id es. Most of our efforts have focused on
the use of Cp(CO)3WH as a hydride donor, since it forms
alcohol complexes that can be isolated. We reported the
kinetics of hydride transfers for a series of metal
Relea se of F r ee Alcoh ols by Disp la cem en t of
Bou n d Alcoh ol by Tr ifla te. These alcohol complexes
are sufficiently stable to be isolated, but they decompose
over the course of several hours at room temperature
in solution. Equation 9 shows the decomposition of the
2-propanol complex, which gives free 2-propanol and Cp-
(CO)3WOTf due to displacement of the alcohol by the
triflate counterion. For the 2-propanol complex, the
reaction is about half completed in 14 h at room temper-
ature. Qualitatively, this reaction is unaffected by the
presence of excess free 2-propanol or by acetone. Other
(19) Song, J .-S.; Szalda, D. J .; Bullock, R. M. J . Am. Chem. Soc. 1996,
118, 11134-11141.
(20) Song, J .-S.; Szalda, D. J .; Bullock, R. M. Inorg. Chim. Acta 1997,
259, 161-172.

Alcohol Complexes of Tungsten
Organometallics, Vol. 20, No. 15, 2001 3341
hydrides,21 and several of these metal hydrides have
also been found to be effective hydride donors in these
ionic hydrogenations. Addition of HOTf to a CD2Cl2
solution containing acetone and the molybdenum hy-
dride Cp(CO)3MoH resulted in the formation of [Cp(CO)3-
Mo(HOiPr)]+OTf- and free HOiPr. The molybdenum
alcohol complex was less stable than the analogous
tungsten complex, with about half of it having decom-
posed in 30 min at 22 °C. The rhenium complex
(CO)5ReH also reacted with acetone and HOTf to give
a high yield of HOiPr; less than 10% of the alcohol
complex [(CO)5Re(HOiPr)]+OTf- was detected by NMR.
Reaction of the manganese hydride (CO)5MnH with
acetone and HOTf at 22 °C resulted in a high yield of
HOiPr and the triflate complex (CO)5MnOTf, with no
evidence for a 2-propanol complex.
Lim ita tion s on Su bstr a tes to be Hyd r ogen a ted .
A variety of ketone and aldehydes can be hydrogenated
by this method, but we found a few cases where Cp-
(CO)3WH and HOTf at room temperature fail to hydro-
genate CdO bonds. Addition of HOTf and Cp(CO)3WH
to 4,4’-dimethoxybenzophenone, (MeO-p-C6H4)2CdO,
resulted in a downfield shift of 0.24-0.27 ppm of the
NMR resonances of the ketone, suggesting it was
protonated. No hydrogenation product was detected
after a day at 22 °C. Similar observations were made
from attempted hydrogenation of xanthone by Cp-
(CO)3WH and HOTf.
resonance of the trans isomer appears as a doublet (J PH
≈ 2 Hz) rather than the singlet of the cis isomer. After
5 min at 22 °C, the trans isomer of [Cp(CO)2(PMe3)W-
(HOnPr)]+OTf- (70%) predominated over cis-[Cp(CO)2-
(PMe3)W(HOnPr)]+OTf- (17%). After 1.5 h, <2% of cis-
[Cp(CO)2(PMe3)W(HOnPr)]+OTf- remained, since it de-
composed to cis-Cp(CO)2(PMe3)WOTf, but trans-[Cp-
(CO)2(PMe3)W(HOnPr)]+OTf- is stable under these con-
ditions.
A similar hydrogenation of acetone by [Cp(CO)2(PMe3)-
W(H)2]+OTf- was observed. Both cis and trans isomers
of the alcohol complex [Cp(CO)2(PMe3)W(HOiPr)]+OTf-
were initially formed. They decompose to release free
HOiPr, with 83% cis-Cp(CO)2(PMe3)WOTf being ob-
served after 20 h at 22 °C. This demonstration that both
H+ and H- could be delivered from a metal-based
system to an organic substrate is significant since it
constitutes a critical step in the development of catalytic
ionic hydrogenations using complexes of Mo and W. We
have recently reported that a series of ketone complexes
[Cp(CO)2(PR3)M(η1-OdCEt2)]+BAr′4- (M ) Mo, W) are
catalyst precursors for hydrogenation of ketones under
mild conditions (23 °C, < 4 atm H2).25
Esters are much more difficult to hydrogenate than
ketones,22 and we found that methyl acetate was not
hydrogenated by Cp(CO)3WH and HOTf at room tem-
perature. Both methyl resonances of CH3CO2CH3 were
shifted 0.36 ppm downfield upon addition of HOTf, but
no evidence for hydrogenation was obtained. These
substrates that are more difficult to hydrogenate provide
impetus for future studies using different reaction
conditions and different metal hydrides than those
examined here.
The hydrogenation of ketones by this tungsten dihy-
dride may proceed through direct metal-to-oxygen pro-
ton transfer from the cationic dihydride [Cp(CO)2(PMe3)-
W(H)2]+OTf- to the ketone, followed by hydride transfer
from the neutral hydride Cp(CO)2(PMe3)WH. An alter-
native that cannot be ruled out is that OTf- serves as a
kinetically competent proton carrier. Darensbourg has
shown that Cl- and other “hard” anions can mediate
deprotonations of metal hydrides and influence ki-
netics of proton transfers.26 In our case, this would
Hyd r ogen a tion s by Ca tion ic Dih yd r id es. The
hydrogenations presented above involve use of HOTf as
the proton source and a neutral metal hydride as the
hydride donor. A more attractive proton source would
be a highly acidic metal hydride. The cationic tungsten
dihydride [Cp(CO)2(PMe3)W(H)2]+OTf- can be isolated
and has been fully characterized, including a crystal
structure.23 This complex reacts quickly with propional-
dehyde at 22 °C to give an n-propanol complex (eq 10)
which exists as a mixture of cis and trans isomers.
-
involve proton transfer to OTf from [Cp(CO)2(PMe3)-
1
W(H)2]+OTf- to give HOTf, which would then protonate
the ketone.
Several prior studies established H NMR criteria to
distinguish cis from trans isomers in these types of
phosphine-substituted W (or Mo) compounds with a
four-legged piano stool geometry.24 The Cp resonance
for the cis isomers appears about 0.2-0.3 ppm downfield
of the resonance for the Cp of the trans isomer. The Cp
Discu ssion
Mech a n istic Con sid er a tion s. A study of the kinet-
ics of ionic hydrogenation of isobutyraldehyde by CpMo-
(CO)3H using CF3CO2H as the acid15 showed that the
apparent rate decreases as the reaction proceeds, since
acid is consumed. But with a buffer present, the reaction
was first-order in acid and first-order in metal hydride.
These kinetics are consistent with the mechanism
(21) (a) Cheng, T.-Y.; Brunschwig, B. S.; Bullock, R. M. J . Am. Chem.
Soc. 1998, 120, 13121-13137. (b) Cheng, T.-Y.; Bullock, R. M. J . Am.
Chem. Soc. 1999, 121, 3150-3155.
(22) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987; p 557.
(23) Bullock, R. M.; Song, J .-S.; Szalda, D. J . Organometallics 1996,
15, 2504-2516.
(24) (a) Ryan, O. B.; Tilset, M.; Parker, V. D. J . Am. Chem. Soc.
1990, 112, 2618-2626. (b) Smith, K.-T.; Tilset, M. J . Organomet. Chem.
1992, 431, 55-64. (c) Kalck, P.; Poilblanc, R. J . Organomet. Chem.
1969, 19, 115-121. (d) Faller, J . W.; Anderson, A. S. J . Am. Chem.
Soc. 1970, 92, 5852-5860.
(25) Bullock, R. M.; Voges, M. H. J . Am. Chem. Soc. 2000, 122,
12594-12595.
(26) (a) Hanckel, J . M.; Darensbourg, M. Y. J . Am. Chem. Soc. 1983,
105, 6979-6980. (b) Darensbourg, M. Y.; Ludvig, M. M. Inorg. Chem.
1986, 25, 2894-2898.

3342 Organometallics, Vol. 20, No. 15, 2001
Song et al.
Sch em e 1
produce H2, protonation of the metal hydride can occur.
Protonation directly at the metal would give a dihydride
[M(H)2]+, or protonation at the metal-hydrogen bond
will produce a dihydrogen complex [M(η2-H2)]+.33 The
stability of the cationic dihydride or dihydrogen complex
can influence the reaction by favoring proton transfer
+
from the MH2 species, rather than elimination of H2
from it. We found earlier that protonation of Cp-
(CO)3WH by HOTf (∼1 equiv) proceeds to only partial
completion.23 The resultant tungsten dihydride, [Cp(CO)3-
W(H)2]+OTf-, not only is highly acidic but has mod-
erate thermal stability as well, being incompletely
decomposed to H2 and Cp(CO)3WOTf after two weeks.
The phosphine-substituted dihydride [Cp(CO)2(PMe3)-
W(H)2]+OTf- is stable enough to be isolated and crys-
tallographically characterized,23 but such stability is
certainly not a requirement. The molybdenum dihy-
drides implicated as intermediates in catalytic ionic
hydrogenations have not been directly observed.25
The C-H bond of the alcohol is formed through a
hydride transfer from metal to carbon. The formation
of the alcohol complexes [Cp(CO)3W(ROH)]+OTf- as the
kinetic product indicates that some W-O bond forma-
tion must be occurring in the transition state for hydride
transfer, before W-H rupture is complete. If this were
not the case, then the thermodynamically more stable
product Cp(CO)3WOTf would have been the kinetic
product.
shown in Scheme 1, involving preequilibrium protona-
tion of the substrate, followed by rate-determining
hydride transfer.
Norton’s group has extensively studied the kinetic and
thermodynamic acidity of metal hydrides,27 and they
recently determined a pKa of 5.6 in CH3CN for [Cp(CO)2-
(PMe3)W(H)2]+.28 Since the pKa of protonated acetone
in CH3CN is about -0.1,29,30 proton transfer from the
tungsten dihydride to acetone is uphill thermodynami-
cally. The hydrogenation still proceeds smoothly, since
fast hydride transfer follows the unfavorable proton
transfer. Norton and co-workers reported a rate con-
stant of k ) 1.2 × 104 M-1 s-1 at 25 °C in CH3CN for
hydride transfer from Cp(CO)2(PPh3)MoH to protonated
acetone.30 Their kinetics and mechanistic studies led to
the conclusion that these were single-step hydride
transfers, rather than the alternative pathway of elec-
tron transfer followed by hydrogen atom transfer.
In our reactions, hydride transfer occurs from CpW-
(CO)3H to protonated ketones. In the absence of acid,
no reaction is observed between ketones and CpW-
(CO)3H or other metal hydrides studied here. In con-
trast, Berke and co-workers found that tungsten hydride
complexes such as WH(CO)2(NO)(PMe3)2 readily insert
aldehydes and ketones into the metal-hydrogen bond.31
The reactivity of metal hydride complexes with nitrosyl
ligands has been reviewed.32
Studies of the kinetics and thermodynamics of cis-
trans interconversions of the neutral metal hydride
complexes Cp(CO)2(PR3)MH (M ) Mo, W) have been
reported, with the equilibria generally favoring the cis
isomer.21a,24d Related cationic complexes also tend to
exhibit a thermodynamic preference for the cis isomer:
Tilset and co-workers found that isomerization of a cis/
-
trans mixture of [Cp(CO)2(PMe3)W(NCCH3)]+BF4 to
the thermodynamic isomer ratio of 95:5 cis:trans was
very slow (t1/2 ≈ 40 h at ambient temperature).24a In
our hydrogenations of acetone and propionaldehyde by
the phosphine-substituted tungsten dihydride [Cp(CO)2-
(PMe3)W(H)2]+OTf-, both cis and trans isomers of the
alcohol complexes [Cp(CO)2(PMe3)W(HOiPr)]+ and [Cp-
(CO)2(PMe3)W(HOnPr)]+ were observed. In both cases,
the trans-[Cp(CO)2(PMe3)W(alcohol)]+ complexes per-
sisted after 1-2 days and were significantly more stable
than the cis isomers. Our cis alcohol complexes may be
thermodynamically favored over the trans alcohol iso-
mers, as found in the examples cited above. We have
no direct evidence for trans to cis isomerization of our
[Cp(CO)2(PMe3)W(alcohol)]+ complexes, however. The
higher kinetic lability of the cis alcohol isomers toward
displacement by triflate means that the formation of the
observed cis-Cp(CO)2(PMe3)WOTf product predomi-
nantly results from displacement of the alcohol by
triflate anion from the cis-[Cp(CO)2(PMe3)W(alcohol)]+-
OTf- isomers.
In the absence of ketone, each of the metal hydrides
Cp(CO)3MoH, (CO)5ReH, and (CO)5MnH reacts quickly
with HOTf at 22 °C to give H2 and the corresponding
metal triflates.13 The successful use of metal hydrides
in these reactions shows that hydride transfer can occur
in the presence of acid and requires that H+ and H- be
transferred to the ketone faster than the formation of
H2 gas. Instead of direct cleavage of the M-H by H+ to
(27) For a review of proton-transfer reactions of metal hydrides,
see: Kristja´nsdo´ttir, S. S.; Norton, J . R. In Transition Metal Hydrides;
Dedieu, A., Ed.; VCH: New York, 1992; Chapter 9; pp 309-359.
(28) Papish, E. T.; Rix, F. C.; Spetseris, N.; Norton, J . R.; Williams,
R. D. J . Am. Chem. Soc. 2000, 122, 12235-12242.
(29) Kolthoff, I. M.; Chantooni, M. K., J r. J . Am. Chem. Soc. 1973,
95, 8539-8546.
The relative trend of stability observed for these
alcohol complexes, with the W complexes being more
stable than those of Mo or Re, is due to both the strength
of the metal-alcohol bond being displaced, as well as
the strength of the metal-triflate bond being formed.
(30) Smith, K.-T.; Norton, J . R.; Tilset, M. Organometallics 1996,
15, 4515-4520.
(31) (a) van der Zeijden, A. A. H.; Bosch, H. W.; Berke, H. Organo-
metallics 1992, 11, 2051-2057. (b) van der Zeijden, A. A. H.; Berke,
H. Helv. Chim. Acta 1992, 75, 513-522. (c) van der Zeijden, A. A. H.;
Veghini, D.; Berke, H. Inorg. Chem. 1992, 31, 5106-5116.
(32) Berke, H.; Burger, P. Comments Inorg. Chem. 1994, 16, 279-
312.
(33) For reviews of dihydrogen complexes, see: (a) Heinekey, D. M.;
Oldham, W. J ., J r. Chem. Rev. 1993, 93, 913-926. (b) J essop, P. G.;
Morris, R. H. Coord. Chem. Rev. 1992, 121, 155-284.

Alcohol Complexes of Tungsten
Organometallics, Vol. 20, No. 15, 2001 3343
Mayer and co-workers reported extensive studies of
oxygen atom transfers between a series of d2 oxo
complexes of W, Mo, and Re.34 On the basis of the
relative directions of inter-metal oxygen transfers, they
concluded the relative metal-oxygen bond strengths for
M(O)ClxL5-x to be W > Mo > Re. Their ordering of bond
strengths agrees with the qualitative relative stability
of our alcohol complexes, despite the significant differ-
ences in ligand sets and formal oxidation states.
of interesting hydrogen-bonding patterns are adopted
by alcohol and water molecules41 bound to low-valent
transition metals. The importance of hydrogen bonding
in biological compounds has long been appreciated,42
and recent interest has focused on hydrogen-bonding
patterns in organometallic and organic compounds for
crystal engineering.43
Exp er im en ta l Section
Str u ctu r a l Com p a r ison s. The X-ray structural data
Gen er a l P r oced u r es. All manipulations were carried out
under an atmosphere of argon using Schlenk or vacuum-line
techniques, or in a Vacuum Atmospheres drybox. 1H NMR
chemical shifts were referenced to the residual proton peak of
CHDCl2 at δ 5.32. Elemental analyses were carried out by
Schwarzkopf Microanalytical Laboratory (Woodside, NY).
NMR spectra were recorded on a Bruker AM-300 spectrometer
(300 MHz for 1H). IR spectra were recorded on a Mattson
Polaris FT-IR spectrometer.
The metal hydrides Cp(CO)3WH,44 Cp(CO)3MoH,44 (CO)5-
MnH,45 (CO)5ReH,46 and [Cp(CO)2(PMe3)W(H)2]+OTf-23 were
prepared by literature methods. THF, Et2O, and hexane were
distilled from Na/benzopheneone, and CH2Cl2 was distilled
from P2O5. The organic substrates were purchased from
commercial sources and used as received. HOTf was purified
by distillation. [H(OEt2)2]+BAr′4- [Ar′ ) 3,5-bis(trifluorometh-
yl)phenyl] was prepared as previously reported.47
P r ep a r a tion of [Cp (CO)3W(HOiP r )]+OTf-. HOTf (100
µL, 1.13 mmol) was added to a solution of Cp(CO)3WH (300
mg, 0.90 mmol) and acetone (80 µL, 1.1 mmol) in CH2Cl2 (10
mL) at 22 °C. The solution was stirred for 30 min, during
which time it became burgundy-red. Et2O (20 mL) and hexane
(10 mL) were added by vacuum transfer, and the dark red
microcrystalline precipitate was collected by filtration. Yield
of [Cp(CO)3W(HOiPr)]+OTf -: 380 mg (78%). Crystals suitable
for diffraction studies were grown by slow diffusion of hexane
into a CH2Cl2 solution of the product at -75 °C. This alcohol
complex was unstable in solution at 22 °C, and after 14 h 50%
of it decomposed to yield Cp(CO)3WOTf and free HOiPr. 1H
NMR (CD2Cl2): δ 7.34 (d, J ) 7.4 Hz, 1H, OH), 6.04 (s, 5H,
Cp), 3.58 (d of septets, J ) 7.3 Hz, 6.3 Hz, 1H, CH), 1.15 (d, J
) 6.3 Hz, 6H, CH3). 13C NMR (CD2Cl2, -73 °C): 225.0 (CO),
222.3 (2 CO), 94.9 (Cp), 83.8 (CH), 22.2 (CH3). IR (KBr):
ν(OH) 3444 (w, br); ν(CO) 2062 (vs), 1983 (vs), 1954 (vs);
ν(C-O) 1022 (s) cm-1. IR (CH2Cl2): ν(CO) 2061 (vs), 1982 (s),
1954 (vs) cm-1. Anal. Calcd for C12H13F3O7SW: C, 26.58; H,
2.42. Found: C, 26.71, H, 2.25.
P r ep a r a tion of [Cp (CO)3W(HOn P r )]+OTf-. HOTf (55 µL,
0.62 mmol) was added to a solution of Cp(CO)3WH (150 mg,
0.45 mmol) and propionaldehyde (40 µL, 0.55 mmol) in
CH2Cl2 (10 mL) at -78 °C. The solution was stirred for 2 h,
during which time the color changed from pale yellow to
burgundy-red. Addition of Et2O (30 mL) resulted in precipita-
tion of a dark red solid, which was collected by filtration and
washed with Et2O (10 mL). Recrystallization from CH2Cl2/
-
for both [Cp(CO)3W(HOiPr)]+OTf
and {Cp(CO)3W-
[CH3CH(OH)CH2C(dO)Ph]}+OTf- show evidence for
hydrogen bonding between the OH of the bound alcohol
ligands and an oxygen of the OTf - anion. The coordina-
tion sphere about the tungsten is remarkably similar
in the two structures (Table 2). The short O‚‚‚O separa-
tion of 2.63(1) Å found in the two examples reported
here are indicative of strong35 hydrogen bonding. This
O‚‚‚O separation is comparable to that determined (2.62
Å) for the unusually strong hydrogen bond of (PMe2-
Ph)3Rh(Otol)(HOtol)36 [tol ) p-tolyl], in which an alcohol
is hydrogen bonded to the rhodium alkoxide. In addition
to the crystallographic study, a calorimetric determi-
nation showed ∆H ) -9.7 ( 0.5 kcal/mol for association
of the alcohol to the rhodium alkoxide.36 Spectroscopic
evidence was reported37 for hydrogen bonding of an
oxygen of the perchlorate counterion to the bound
alcohol ligand in [ReH(CO)(NO)(PPh3)2(MeOH)]+ClO4
.
-
Beck and co-workers reported17 a crystal structure of
the ruthenium alcohol complex [Cp(CO)(PPh3)Ru-
-
(EtOH)]+BF4 that indicated O-H‚‚‚F hydrogen bond-
ing. In contrast, Gladysz and co-workers prepared18
a
series of low-valent rhenium alcohol complexes of for-
-
mula [CpRe(NO)(PPh3)(ROH)]+BF4 and noted that
their spectroscopic data did not provide a strong case
for hydrogen bonding.
Compared to alcohol complexes, far more structural
data are available on H2O ligands exhibiting hydrogen
bonding. The aqua ligand of [IrH2(THF)(H2O)(PPh3)2]+-
SbF6-‚THF exhibits hydrogen bonding to both the F of
-
the SbF6 and the O of a THF molecule in the lattice
(O‚‚‚O separation of 2.70(2) Å).38 The H2O bound to
tungsten in W(CO)3(PiPr3)2(H2O)‚THF exhibits hydro-
gen bonding, with the crystal structure39 showing both
a hydrogen bond to lattice THF and an unusual
O-H‚‚‚O hydrogen bond of the OH to the oxygen of a
carbonyl ligand of an adjacent molecule (O‚‚‚O separa-
tion of 2.792 Å). In some cases different oxygens of the
same OTf- anion form hydrogen bonds to different
water molecules on the same metal.40 Clearly a variety
(34) Over, D. E.; Critchlow, S. C.; Mayer, J . M. Inorg. Chem. 1992,
31, 4643-4648.
(41) Numerous citations to low-valent aqua complexes are given in
ref 39. A more recent article (Takahashi, Y.; Akita, M.; Hikichi, S.;
Moro-oka, Y. Inorg. Chem. 1998, 37, 3186-3194) presents a series of
Ru aqua complexes hydrogen bonded to OTf- and THF; this article
has a discussion of the various hydrogen-bonding modes encountered.
(42) J effrey, G. A.; Saenger, W. Hydrogen Bonding in Biological
Structures; Springer-Verlag: New York, 1991.
(43) (a) Braga, D.; Grepioni, F.; Sabatino, P.; Desiraju, G. R.
Organometallics 1994, 13, 3532-3543. (b) Desiraju, G. R. Angew.
Chem., Int. Ed. Engl. 1995, 34, 2311-2327. (c) Braga, D.; Grepioni,
F.; Desiraju, G. R. Chem. Rev. 1998, 98, 1375-1405.
(44) Keppie, S. A.; Lappert, M. F. J . Chem. Soc. (A) 1971, 3216-
3220.
(35) Gilli, P.; Bertolasi, V.; Ferretti, V.; Gilli, G. J . Am. Chem. Soc.
1994, 116, 909-915. This article discusses bonding in O-H‚‚‚O
hydrogen bonds in the context of structural data and refers to the loose
definitions of bond strength according to O‚‚‚O distances as very strong
(<2.50 Å), strong (2.50-2.65 Å), medium (2.65-2.80 Å), and weak
(>2.80 Å).
(36) Kegley, S. E.; Schaverien, C. J .; Freundenberger, J . H.; Berg-
man, R. G.; Nolan, S. P.; Hoff, C. D. J . Am. Chem. Soc. 1987, 109,
6563-6565.
(37) Grundy, K. R.; Robertson, K. N. Inorg. Chem. 1985, 24, 3898-
3903.
(38) Luo, X.-L.; Schulte, G. K.; Crabtree, R. H. Inorg. Chem. 1990,
29, 682-686.
(39) Kubas, G. J .; Burns, C. J .; Khalsa, G. R. K.; Van Der Sluys, L.
S.; Kiss, G.; Hoff, C. D. Organometallics 1992, 11, 3390-3404.
(40) Svetlanova-Larsen, A.; Zoch, C. R.; Hubbard, J . L. Organome-
tallics 1996, 15, 3076-3087.
(45) Bullock, R. M.; Rappoli, B. J . J . Organomet. Chem. 1992, 429,
345-368.
(46) Urbancic, M. A.; Shapley, J . R. Inorg. Synth. 1989, 26, 77-80.
(47) Brookhart, M.; Grant, B.; Volpe, A. F., J r. Organometallics 1992,
11, 3920-3922.

3344 Organometallics, Vol. 20, No. 15, 2001
Song et al.
hexane at -78 °C gave [Cp(CO)3W(HOnPr)]+OTf- as a micro-
crystalline solid (210 mg, 86% yield). 1H NMR (CD2Cl2): δ 7.75
(t, br, J ) 4.6 Hz, 1H, OH), 6.06 (s, 5H, Cp), 3.56 (dt, J ) 7.4
Hz, 4.6 Hz, 2H, OCH2), 1.50 (sextet, J ) 7.4 Hz, 2H,
OCH2CH2), 0.84 (t, J ) 7.4 Hz, 3H, CH3). 13C NMR (CD2Cl2,
-73 °C): 224.4 (CO), 221.9 (2 CO), 94.5 (Cp), 80.3 (OCH2),
23.3 (OCH2CH2), 8.5 (CH2CH3). IR (KBr): ν(OH) 3449 (w, br),
(30 mL) was slowly added. The resulting precipitate was
isolated, washed with hexane (50 mL), and dried under
vacuum to give [Cp(CO)3W(HOiPr)]+[BAr′4]- as a purple-red
solid (171 mg, 69%). This reaction can also be carried out in
CH2Cl2, but as in this reaction in toluene, no reaction appears
1
to occur until the solvent was removed. H NMR (CD2Cl2): δ
7.73 (br, 8H, o-H), 7.58 (br, 4H, p-H), 5.99 (s, 5H, Cp), 3.71 (d
of septets, J ) 7.9 Hz, 6.3 Hz, 1H, CH), 2.41 (d, J ) 7.9 Hz,
1H, OH), 1.18 (d, J ) 6.3 Hz, 6H, CH3). 13C NMR (CD2Cl2,
-13 °C): 222.4 (2 CO), 221.8 (CO), 161.6 (1:1:1:1 quartet, J CB
ν(CO) 2051 (s), 1977 (s, sh), 1953 (vs), ν(C-O) 1026 (s) cm-1
.
IR (CH2Cl2): ν(CO) 2061 (vs), 1981 (s), 1958 (vs) cm-1. Anal.
Calcd for C12H13F3O7SW: C, 26.58; H, 2.42. Found: C, 26.07,
H, 2.38.
2
) 48.2 Hz, ipso-C), 134.7 (o-C), 128.7 (br, q, J CF ) 30.5 Hz,
1
P r ep a r a tion of [Cp (CO)3W(HOC6H11)]+OTf-. HOTf (70
µL, 0.79 mmol) was added to a solution of Cp(CO)3WH (215
mg, 0.644 mmol) and cyclohexanone (80 µL, 0.77 mmol) in
CH2Cl2 (10 mL) at 22 °C. The solution was stirred for 30 min,
during which time it became burgundy-red. Et2O (20 mL) and
hexane (10 mL) were added by vacuum transfer to yield the a
dark red microcrystalline precipitate, which was collected by
filtration, washed with Et2O (10 mL) and hexane (30 mL), and
dried under vacuum to give [Cp(CO)3W(HOC6H11)]+OTf- (213
m-C), 124.5 (q, J CF ) 272 Hz, CF3), 117.5 (p-C), 95.7 (Cp),
65.6 (CH), 14.5 (CH3). IR (CH2Cl2): ν(CO) 2062 (s), 1986 (m),
1964 (vs) cm-1. Anal. Calcd for C43H25BF24O4W: C, 41.13; H,
2.01. Found: C, 40.78; H, 1.98.
P r ep a r a tion of {Cp (CO)3W[CH3CH(OH)CH2C(dO)-
P h ]}+OTf-. HOTf (100 µL, 1.13 mmol) was added to a solution
of Cp(CO)3WH (150 mg, 0.45 mmol) and 1-phenyl-1,3-butane-
dione (100 mg, 0.62 mmol) in CH2Cl2 (10 mL) at 22 °C. The
solution was stirred for 30 min, during which time it became
burgundy-red. Et2O (30 mL) and hexane (10 mL) were added
by vacuum transfer to yield a dark red solid, which was
collected by filtration, washed with Et2O (10 mL), and dried
under vacuum to give {Cp(CO)3W[CH3CH(OH)CH2C(dO)-
Ph]}+OTf- (173 mg, 59% yield). Crystals suitable for diffraction
studies were grown by slow diffusion of hexane into a CH2Cl2
1
mg, 57% yield). H NMR (CD2Cl2): δ 7.35 (d, J ) 7.3 Hz, 1H,
OH), 6.05 (s, 5H, Cp), 3.16 (m, 1H, OCH), 1.88-1.76 (m, 4H),
1.53-1.06 (m, 6H). 13C NMR (CD2Cl2, -33 °C): 225.4 (CO),
222.3 (2 CO), 95.3 (Cp), 89.3, 33.1, 24.5 (cyclohexyl carbons).
IR (KBr): ν(OH) 3443 (w,br), ν(CO) 2064 (vs), 1985 (s), 1948
(vs), ν(C-O) 1024 (s) cm-1. IR (CH2Cl2): ν(CO) 2060 (vs), 1982
(s), 1953 (vs) cm-1. Anal. Calcd for C15H17F3O7SW: C, 30.94;
H, 2.94. Found: C, 30.67, H, 2.81.
1
solution of the product at -35 °C. H NMR (CD2Cl2): δ 7.97-
7.47 (m, 5H, Ph), 6.00 (s, 5H, Cp), 4.14 (br s, 1H, OCH), 3.56
(dd, J ) 18.6 Hz, 8.5 Hz, 1H, CH2), 2.96 (dd, J ) 18.6 Hz, 3.5
Hz, 1H, CH2), 1.21 (d, J ) 6.5 Hz, 3H, CH3). 13C NMR
(CD2Cl2, -53 °C): 225.3 (CO), 224.7 (CO), 220.2 (CO), 195.8
(PhC(dO)), 135.0 (ipso-C), 133.5 (p-C), 128.3 (o-C), 127.5 (m-
C), 95.0 (Cp), 81.1 (CH(OH)), 45.3 (C(dO)CH2), 19.7 (CH3). IR
(KBr): ν(OH) 3443 (w, br); ν(CO) 2059 (vs), 1968 (vs), 1942
(vs); ν(CdO) 1678 (s); ν(C-O) 1023 (s) cm-1. IR (CH2Cl2):
P r epar ation of [Cp(CO)3W(2-adam an tan ol)]+OTf-. HOTf
(60 µL, 0.68 mmol) was added to a solution of Cp(CO)3WH (200
mg, 0.600 mmol) and 2-adamantanone (110 mg, 0.73 mmol)
in CH2Cl2 (10 mL) at 22 °C. The solution was stirred for 30
min, during which time it became burgundy-red. Et2O (30 mL)
was added by vacuum transfer to yield the dark red solid,
which was collected by filtration, washed with Et2O (30 mL),
and dried under vacuum to give [Cp(CO)3W(2-adamanta-
ν(CO) 2059 (vs), 1981 (s), 1955 (vs); ν(CdO) 1686 (m) cm-1
.
1
nol)]+OTf- (270 mg, 71% yield). H NMR (CD2Cl2): δ 6.96 (d,
Anal. Calcd for C19H17F3O8SW: C, 35.31; H, 2.65. Found: C,
35.46, H, 2.85.
J ) 4.6 Hz, 1H, OH), 6.08 (s, 5H, Cp), 3.51 (m, 1H, OCH),
2.00-1.52 (m, 14H). 13C NMR (CD2Cl2, -33 °C): 224.9 (CO),
221.7 (2 CO), 94.9 (Cp), 93.6 (1C, OCH), 35.9 (1C), 35.3 (2C),
31.9 (2C), 29.4 (2C), 25.9 (2C). IR (KBr): ν(OH) 3449 (w,br),
Gen er a l P r oced u r e for Rea ction s Ca r r ied Ou t in NMR
Tu bes. Reactions between ketones (or aldehydes) and metal
hydrides carried out in NMR tubes were prepared by adding
a measured quantity of Cp(CO)3WH or other metal hydride,
the ketone (or aldehyde), and an internal integration standard
(1,2-dichloroethane or bibenzyl) to a screw-capped NMR tube
in a drybox. CD2Cl2 was added, and the volume of the solution
was calculated from the height of the solution in the NMR tube
using a reported formula.48 After measuring the initial NMR
spectrum, HOTf was added to the solution, and spectra were
taken over the course of the reaction and integrated vs the
internal standard. 1H NMR (CD2Cl2) spectrum of Cp(CO)3-
WOTf (observed as a decomposition product of these alcohol
complexes): δ 5.99 (s).
ν(CO) 2051 (vs), 1977 (s, sh), 1952 (vs), ν(C-O) 1026 (s) cm-1
.
IR (CH2Cl2): ν(CO) 2061 (vs), 1984 (s), 1950 (vs) cm-1. Anal.
Calcd for C19H21F3O7SW: C, 35.98; H, 3.50. Found: C, 36.27,
H, 3.50.
P r ep a r a tion of {Cp (CO)3W[CH3CH(OH)C(dO)CH3]}+-
OTf-. HOTf (100 µL, 1.13 mmol) was added to a solution of
Cp(CO)3WH (200 mg, 0.600 mmol) and 2,3-butanedione (60
µL, 0.68 mmol) in CH2Cl2 (10 mL) at 22 °C. The solution was
stirred for 10 min, during which time it became burgundy-
red. Et2O (30 mL) and hexane (10 mL) were added by vacuum
transfer to yield a dark red solid, which was collected by
filtration, washed with Et2O (10 mL), and dried under vacuum
to give [Cp(CO)3W{CH3CH(OH)C(dO)CH3}]+OTf- (147 mg,
Ion ic Hyd r ogen a tion of 2-Bu ta n on e by Cp (CO)3WH
a n d HOTf. Using the general procedure described above for
NMR tube reactions, HOTf (3 µL, 0.034 mmol) was added to
a solution of Cp(CO)3WH (19 mg, 0.057 mmol), 2-butanone (3.5
µL, 0.039 mmol), and 1,2-dichloroethane (3 µL) in CD2Cl2 (0.60
mL). After 30 min at 22 °C, the 1H NMR spectrum of the
burgundy-red solution showed the formation of [Cp(CO)3W-
(2-butanol)]+OTf- in 83% yield. After 1 h at 22 °C, [Cp(CO)3W-
1
43% yield). H NMR (CD2Cl2): δ 8.61 (br s, 1H, OH), 6.10 (s,
5H, Cp), 3.93 (br s, 1H, OCH), 2.09 (s, 1H, CH3CdO), 1.35 (d,
J ) 6.9 Hz, 3 H, CH3CH). 13C NMR (CD2Cl2, -53 °C): 224.1
(CO), 223.2 (CO), 221.2 (CO), 203.9 (CdO), 95.0 (Cp), 86.5
(OCH), 25.1 (CH3CdO), 17.5 (CH3CH). IR (KBr): ν(OH) 3442
(w,br), ν(CO) 2064 (s), 1964 (s, sh), 1957 (vs); ν(CdO) 1725;
ν(C-O) 1025 (s) cm-1. IR (CH2Cl2): ν(CO) 2062 (vs), 1985 (s),
1951 (vs); ν(CdO) 1735 (m) cm-1. Anal. Calcd for C13H13F3O8-
SW: C, 27.38; H, 2.30. Found: C, 27.59, H, 2.14.
P r ep a r a tion of [Cp (CO)3W(HOiP r )]+[BAr ′4]-. Cp(CO)3-
WH (80 mg, 0.24 mmol), [H(Et2O)2]+[BAr′4]- (200 mg, 0.20
mmol), and toluene (10 mL) were placed in a Schlenk flask,
which was cooled to -78 °C. Acetone (22 µL, 0.30 mmol) was
added, and the reaction mixture was warmed to 22 °C and
stirred for 1 h. No color change was observed. The solvent was
removed under vacuum, and the color slowly darkened. The
purple-red residue was dissolved in Et2O (10 mL), and hexane
(2-butanol)]+OTf- (93%) and Cp(CO)3WOTf (4%) were ob-
-
served. [Cp(CO)3W(CH3CH2CH(OH)CH3)]+OTf
:
1H NMR
(CD2Cl2): δ 6.03 (s, 5H, Cp), 5.66 (d, J ) 7.8 Hz, 1H, OH),
3.37 (septet, J ) 6.9 Hz, 1H, CH), 1.57-1.34 (m, 2H, CH2),
1.11 (d, J ) 6.4 Hz, 3H, CH(OH)CH3), 0.86 (t, J ) 7.4 Hz, 3H,
CH3CH2).
Ion ic Hyd r ogen a tion of P iva la ld eh yd e by Cp (CO)3WH
a n d HOTf. Using the general procedure described above for
(48) Bryndza, H. E.; Calabrese, J . C.; Marsi, M.; Roe, D. C.; Tam,
W.; Bercaw, J . E. J . Am. Chem. Soc. 1986, 108, 4805-4813.

Alcohol Complexes of Tungsten
Organometallics, Vol. 20, No. 15, 2001 3345
NMR tube reactions, HOTf (6 µL, 0.068 mmol) was added to
a solution of Cp(CO)3WH (18 mg, 0.054 mmol), pivalaldehyde
(4 µL, 0.036 mmol), and 1,2-dichloroethane (3 µL) in CD2Cl2
Ion ic Hyd r ogen a tion of Aceton e by (CO)5Mn H a n d
HOTf. Using the general procedure described above for NMR
tube reactions, HOTf (10 µL, 0.11 mmol) was added to a
solution of (CO)5MnH (19 mg, 0.097 mmol), acetone (4 µL,
0.054 mmol), and 1,2-dichloroethane (3.5 µL) in CD2Cl2 (0.52
mL). After 5 min at 22 °C, the 1H NMR spectrum of the
resulting yellow solution showed the formation of HOiPr in a
quantitative yield. The integration over the hydride region
indicated that 1.06 equiv of (CO)5MnH was consumed. A
separate experiment monitored by IR spectroscopy confirmed
the formation of (CO)5MnOTf 49 as the organometallic product.
Ion ic H yd r ogen a t ion of Acet on e b y (CO)5R eH a n d
HOTf. Using the general procedure described above for NMR
tube reactions, HOTf (15 µL, 0.17 mmol) was added to a
solution of (CO)5ReH (80 mg, 0.24 mmol), acetone (8 µL, 0.11
mmol), and 1,2-dichloroethane (4 µL) in CD2Cl2(0.65 mL). After
5 min at 22 °C, an 1H NMR spectrum showed the formation
of HOiPr and [(CO)5Re(HOiPr)]+OTf- in a 91:9 ratio. After 20
min at 22 °C, only ∼3% of [(CO)5Re(HOiPr)]+OTf- and 97% of
HOiPr were observed in the 1H NMR spectrum. 1H NMR
(CD2Cl2) of [(CO)5Re(HOiPr)]+OTf -: δ 7.00 (br, OH, tentative
assignment), δ 3.97 (br, 1H, CH), 1.33 (d, J ) 6.2 Hz, 6H, CH3).
Rea ction of [Cp (CO)3W(HOiP r )]+[BAr ′4]- w ith Aceton e.
The reaction between acetone (1 µL, 0.015 mmol) and
[Cp(CO)3W(HOiPr)]+[BAr′4]- (19 mg, 0.015 mmol) in CD2Cl2
(0.65 mL) was monitored by 1H NMR. Slow displacement of
the alcohol ligand by acetone was observed. After 5 days at
22 °C, a 53:47 mixture of [Cp(CO)3W(HOiPr)]+[BAr′4]- and
[Cp(CO)3W(acetone)]+[BAr′4]- was observed, along with free
1
(0.55 mL). After 5 min at 22 °C, the H NMR spectrum of the
resulting burgundy-red solution showed the formation of [Cp-
(CO)3W(2,2-dimethyl-1-propanol)]+OTf- in 94% yield. After 16
h at 22 °C, [Cp(CO)3W(2,2-dimethyl-1-propanol)]+OTf- (31%)
and free 2,2-dimethyl-1-propanol (69%) were observed. {Cp-
(CO)3W[HOCH2C(CH3)3}+OTf-: 1H NMR (CD2Cl2): δ 7.30 (t,
J ) 5.4 Hz, 1H, OH), 6.11 (s, 5H, Cp), 3.33 (d, J ) 5.4 Hz, 2H,
CH2), 0.83 (s, 9H, CH3).
Ion ic Hyd r ogen a tion of 4-P h en yl-2-bu ta n on e by Cp -
(CO)3WH a n d HOTf. Using the general procedure described
above for NMR tube reactions, HOTf (3 µL, 0.034 mmol) was
added to a solution of Cp(CO)3WH (7 mg, 0.021 mmol),
4-phenyl-2-butanone (3 µL, 0.020 mmol), and 1,2-dichloroet-
hane (4 µL) in CD2Cl2 (0.61 mL). After 30 min at 22 °C, the
1H NMR spectrum showed the formation of [Cp(CO)3W(4-
phenyl-2-butanol)]+OTf- in 88% yield. After 40 h at 22 °C, [Cp-
(CO)3W(4-phenyl-2-butanol)]+OTf- had decomposed to give
Cp(CO)3WOTf (81%) and 4-phenyl-2-butanol (81%).
[Cp(CO)3W(PhCH2CH2CH(OH)CH3)]+OTf-: 1H NMR (CD2-
Cl2): δ 7.33-7.14 (m, 5H, Ph), 6.36 (d, J ) 7.9 Hz, 1H, OH),
5.99 (s, 5H, Cp), 3.39 (m, 1H, CH), 2.56 (t, J ) 6.8 Hz, 2H,
PhCH2), 1.90-1.64 (m, 2H, PhCH2CH2), 1.16 (d, J ) 6.3 Hz,
3H, CH3). 4-Phenyl-2-butanol: 1H NMR (CD2Cl2): δ 7.29-7.14
(m, 5H, Ph), 4.33 (sextet, J ) 6.4 Hz, 1H, CH), 2.71 (m, 2H,
PhCH2), 2.04 (m, 2H, PhCH2CH2), 1.42 (d, J ) 6.4 Hz, 3H,
CH3).
Ion ic Hyd r ogen a tion of Acetop h en on e by Cp (CO)3WH
a n d HOTf. Using the general procedure described above for
NMR tube reactions, HOTf (14 µL, 0.16 mmol) was added to
a solution of Cp(CO)3WH (32 mg, 0.096 mmol), acetophenone
(4 µL, 0.034 mmol), and 1,2-dichloroethane (4 µL) in CD2Cl2
(0.57 mL). After1 h at 22 °C, the 1H NMR spectrum of the
resulting wine-red solution showed the formation of ethylben-
zene in 50% yield, along with Cp(CO)3WOTf. After 3 h at 22
°C, the yield of ethylbenzene had increased to 91%, and only
8% acetophenone remained (the remaining acetophenone is
apparently partially protonated; its CH3 resonance appears
at δ 3.17, vs δ 2.59 for free acetophenone in the absence of
HOTf).
1
HOiPr. H NMR (CD2Cl2) of [Cp(CO)3W(acetone)]+[BAr′4]-: δ
6.07 (s, 5H, Cp), 2.39 (s, 6H, Me). 1H NMR (CD2Cl2) of
2-propanol: δ 3.93 (m, 1H, CH), 2.12 (br, 1H, OH), 1.23 (d, J
) 6.2 Hz, 6H, CH3).
Rea ction of [Cp (CO)2(P Me3)W(H)2]+OTf- w ith P r op i-
on a ld eh yd e. Propionaldehyde (2 µL, 0.028 mmol) was added
to a solution of [Cp(CO)2(PMe3)W(H)2]+OTf- (16 mg, 0.030
mmol) and 1,2-dichloroethane (2 µL) in CD2Cl2 (0.60 mL) in
1
an NMR tube. After 5 min at 22 °C, the H NMR spectrum of
the wine-red solution showed the formation of trans-[Cp(CO)2-
(PMe3)W(HOnPr)]+OTf- (70%), cis-[Cp(CO)2(PMe3)W(HOn-
Pr)]+OTf- (17%), and cis-Cp(CO)2(PMe3)WOTf (3%). After 1.5
h, cis-[Cp(CO)2(PMe3)W(HOnPr)]+OTf- (1%) and cis-Cp(CO)2-
(PMe3)WOTf (23%) were observed along with free HOnPr,
while trans-[Cp(CO)2(PMe3)W(HOnPr)]+OTf- remained. Little
change in the amount of trans-[Cp(CO)2(PMe3)W(HOnPr)]+OTf-
was observed after 2 days. trans-[Cp(CO)2(PMe3)W(HOn-
Pr)]+OTf-: 1H NMR (CD2Cl2): δ 6.77 (t, J ) 4.7 Hz, 1H, OH),
5.53 (d, J PH ) 2.6 Hz, 5H, Cp), 3.54 (br, q, J ) 7.0 Hz, 2H,
OCH2), 1.68 (d, J PH ) 9.8 Hz, 9H, PMe3), 1.48 (sextet, J ) 7.2
Hz, 2H, OCH2CH2), 0.82 (t, J ) 7.4 Hz, 3H, CH3). cis-[Cp(CO)2-
(PMe3)W(HOnPr)]+OTf-: 1H NMR (CD2Cl2): δ 6.61 (t, J ) 4.7
Hz, 1H, OH), 5.86 (s, 5H, Cp), 3.54 (br, q, J ) 7.0 Hz, 2H,
OCH2), 1.69 (d, J PH ) 9.8 Hz, 9H, PMe3), 1.48 (sextet, J ) 7.2
Hz, 2H, OCH2CH2), 0.81 (t, J ) 7.4 Hz, 3H, CH3). cis-Cp(CO)2-
Ion ic Hyd r ogen a tion of 1,3,5-Tr ioxa n e by Cp (CO)3WH
a n d HOTf. Using the general procedure described above for
NMR tube reactions, HOTf (6 µL, 0.068 mmol) was added to
a solution of Cp(CO)3WH (15 mg, 0.045 mmol), 1,3,5-trioxane
(5.4 mg, 0.060 mmol), and 1,2-dichloroethane (3 µL) in
1
CD2Cl2 (0.64 mL). After 5 min at 22 °C, the H NMR spectrum
showed the formation of [Cp(CO)3W(HOMe)]+OTf- (86% yield).
[Cp(CO)3W(HOMe)]+OTf-: 1H NMR (CD2Cl2): δ 7.40 (v br,
1H, OH), 6.05 (s, 5H, Cp), 3.57 (s, 3H, CH3).
1
(PMe3)WOTf: H NMR (CD2Cl2): δ 5.76 (s, 5H, Cp), 1.62 (d,
J PH ) 10.0 Hz, 9H, PMe3).
Rea ction of [Cp (CO)2(P Me3)W(H)2]+OTf- w ith Aceton e.
Acetone (3 µL, 0.041 mmol) was added to a solution of
[Cp(CO)2(PMe3)W(H)2]+OTf- (22 mg, 0.041 mmol) and 1,2-
dichloroethane (2.5 µL) in CD2Cl2 (0.60 mL). After 5 min at
22 °C, the reaction was only partially complete and showed
cis-[Cp(CO)2(PMe3)W(HOiPr)]+OTf- (47%), trans-[Cp(CO)2-
(PMe3)W(HOiPr)]+OTf- (11%), and cis-Cp(CO)2(PMe3)WOTf
(8%). After 1 h at 22 °C, <5% acetone remained, and cis-[Cp-
(CO)2(PMe3)W(HOiPr)]+OTf- (32%), trans-[Cp(CO)2(PMe3)-
W(HOiPr)]+OTf- (16%), and cis-Cp(CO)2(PMe3)WOTf (49%)
Ion ic Hyd r ogen a tion of Aceton e by Cp (CO)3MoH a n d
HOTf. Using the general procedure described above for NMR
tube reactions, HOTf (10 µL, 0.11 mmol) was added to a
solution of Cp(CO)3MoH (19 mg, 0.077 mmol), acetone (4 µL,
0.054 mmol), and 1,2-dichloroethane (4 µL) in CD2Cl2 (0.56
mL). After 5 min at 22 °C, the 1H NMR spectrum of the
resulting purple solution showed the formation of [Cp(CO)3-
Mo(HOiPr)]+OTf- (77%) and 2-propanol (23%) along with Cp-
(CO)3MoOTf (δ 5.88). After 30 min at 22 °C, approximately
equal amounts of [Cp(CO)3Mo(HOiPr)]+OTf- and HOiPr were
present, and after 20 h at 22 °C, no alcohol complex was
1
were observed in the H NMR spectrum. After 20 h at 22 °C,
detected, and Cp(CO)3MoOTf and free HOiPr were the pre-
<3% cis-[Cp(CO)2(PMe3)W(HOiPr)]+OTf- was observed, along
dominant products. [Cp(CO)3Mo(HOiPr)]+OTf
:
1H NMR
-
(CD2Cl2): δ 5.90 (s, 5H, Cp), 4.90 (br, 1H, OH), 3.46 (br, 1H,
CH), 1.18 (d, J ) 6.3 Hz, 6H, CH3).
(49) Nitschke, J .; Schmidt, S. P.; Trogler, W. C. Inorg. Chem. 1985,
24, 1972-1978.

3346 Organometallics, Vol. 20, No. 15, 2001
Song et al.
with trans-[Cp(CO)2(PMe3)W(HOiPr)]+OTf- (14%) and cis-Cp-
(CO)2(PMe3)WOTf (83%). trans-[Cp(CO)2(PMe3)W(HOiPr)]+OTf-:
1H NMR (CD2Cl2): δ 6.37 (d, J ) 7.7 Hz, 1H, OH), 5.52 (d,
J PH ) 2.7 Hz, 5H, Cp), 3.57 (br, septet, J ) 6.4 Hz, 1H, OCH),
1.68 (d, J PH ) 9.8 Hz, 9H, PMe3), 1.12 (d, J ) 6.4 Hz, 6H, CH3).
cis-[Cp(CO)2(PMe3)W(HOiPr)]+OTf-: 1H NMR (CD2Cl2): δ 5.93
(t, J ) 7.7 Hz, 1H, OH), 5.86 (s, 5H, Cp), 3.57 (br, septet, J )
6.4 Hz, 2H, OCH2), 1.67 (d, J PH ) 9.8 Hz, 9H, PMe3), 1.16 (dd,
J ) 6.3 Hz, J ) 2.0 Hz, 6H, CH3).
Selectivity in Ion ic Hyd r ogen a tion . Ald eh yd e vs Ke-
ton e. Using the general procedure described above for NMR
tube reactions, HOTf (4 µL, 0.045 mmol) was added to a
solution of Cp(CO)3WH (20 mg, 0.060 mmol), acetone (3 µL,
0.041 mmol), pivalaldehyde (4.5 µL, 0.041 mmol), and 1,2-
dichloroethane (4 µL) in CD2Cl2 (0.63 mL). After 5 min at 22
°C, the 1H NMR spectrum of the resulting burgundy-red
solution showed the formation of [Cp(CO)3W(2,2-dimethyl-1-
propanol)]+OTf- (88% yield). There was no evidence for
hydrogenation of acetone, but it does appear to have been
partially protonated as its CH3 resonance moved from δ 2.12
in the absence of acid to δ 2.15.
temperature device and cooled to 200 K for the collection of
diffraction data. Diffraction data indicated triclinic symmetry
for [Cp(CO)3W(HOiPr)]+OTf- and monoclinic symmetry with
systematic absences consistent with space group P21/n for
{Cp(CO)3W[CH3CH(OH)CH2C(dO)Ph]}+OTf-. Space group P
was used for the solution and refinement of[Cp(CO)3W-
(HOiPr)]+OTf-. Crystal data and information about the data
collection are provided in Table 1 and the Supporting Informa-
tion.
Deter m in a tion a n d Refin em en t of th e Str u ctu r e. The
structures50 were solved by standard heavy atom Patterson
methods. In the least-squares refinement,50 anisotropic tem-
perature parameters were used for all the non-hydrogen atoms.
Hydrogen atoms, except the one on the alcohol oxygen in both
of the two structures, which was located on a difference Fourier
map and fixed in that location, were placed at calculated
positions and allowed to “ride” on the atom to which they were
attached. A common isotropic thermal parameter was refined
for the hydrogen atoms in each structure. A Gaussian absorp-
tion correction50 was used for [Cp(CO)3W(HOiPr)]+OTf-. For
{Cp(CO)3W[CH3CH(OH)CH2C(dO)Ph]}+OTf- the data were
corrected using a Fourier absorption correction (XABS2).51
Ion ic Hyd r ogen a tion of 1,1-Dim eth oxya ceton e by Cp -
(CO)3WH a n d HOTf. Using the general procedure described
above for NMR tube reactions, HOTf (3 µL, 0.034 mmol) was
added to a solution of Cp(CO)3WH (16 mg, 0.048 mmol), 1,1-
dimethoxyacetone (4 µL), and 1,2-dichloroethane (3 µL) in
Ack n ow led gm en t. This research was carried out
at Brookhaven National Laboratory under contract DE-
AC02-98CH10886 with the U.S. Department of Energy
and was supported by its Division of Chemical Sciences,
Office of Basic Energy Sciences.
1
CD2Cl2 (0.55 mL). After 5 min at 22 °C, the H NMR spectrum
of the resulting wine-red solution showed the formation of the
alcohol complex, [Cp(CO)3W(1,1-dimethoxy-2-propanol)]+OTf-
(60%). Free 1,1-dimethoxy-2-propanol (5%) and unreacted 1,1-
dimethoxyacetone (21%) were also observed. [Cp(CO)3W(1,1-
dimethoxy-2-propanol)]+OTf-: 1H NMR (CD2Cl2): δ 7.57 (d,
J ) 8.5 Hz, 1H, OH), 6.06 (s, 5H, Cp), 4.14 (d, J ) 6.4 Hz, 1H,
CH(OCH3)2), 3.46 (s, 3H, OCH3), 3.39 (s, 3H, OCH3), 3.33 (m,
1H, HOCH), 1.08 (d, J ) 6.6 Hz, 3H, CHCH3).
Collection a n d Red u ction of X-r a y Da ta . X-ray data sets
were collected on crystals of [Cp(CO)3W(HOiPr)]+OTf- and
{Cp(CO)3W[CH3CH(OH)CH2C(dO)Ph]}+OTf-. Crystals of each
of these alcohol complexes were coated with Vaseline and
sealed inside a glass capillary, which was then transferred to
an Enraf Nonius CAD-4 diffractometer equipped with a low-
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
information for [Cp(CO)3W(HOiPr)]+OTf- and {Cp(CO)3W-
[CH3CH(OH)CH2C(dO)Ph]}+OTf-: atomic coordinates, tables
of complete bond lengths and angles, anisotropic displacement
parameters for the non-hydrogen atoms, hydrogen coordinates,
and distances and angles for hydrogen bonds. This material
is available free of charge via the Internet at http://pubs.acs.org.
OM010222L
(50) Sheldrick, G. M. SHELXL Version 5; Siemens Analytical
Instruments, Inc.: Madison WI; 1994.
(51) Parkin, S.; Moezzi, B.; Hope, H. J . Appl. Crystallogr. 1995, 28,
53-56.