1,2-Bis(dimethylphosphino)ethanehydridomesitylidyne-tungsten(IV). Hydride activation via the trans influence

Article abstract of DOI:10.1021/om000332c

The synthesis of the tungsten carbyne hydride complex trans-W(CMes)(dmpe)₂H, 7, which is obtained from the borohydride complex trans-W(CMes)(η¹-BH₄)(dmpe)2, 6, (dmpe = Me₂-PCH₂CH₂PMe₂) is reported. 6 is readily prepared from trans-W(CMes)(dmpe)₂d, 5, which is prepared from [W(CO)₅C(O)Mes][N(CH₃)₄] via the isolable intermediates trans-W(CMes)-(CO)₂(Py)₂Cl, 2, and trans-W(CMes)(CO)[P(OMe)₃]₃Cl, 3. 7 was spectroscopically fully characterized, and reactivity studies have revealed its potential in hydrogen transfer reactions. The results of studies into the reactivity of the W-H bond toward small unsaturated molecules, such as propionaldehyde, benzaldehyde, acetone, acetophenone, and benzophenone, to give the corresponding alkoxides trans-W(CMes)(dmpe)₂(OCHR′R″) (R′ = H, R″ = Pr 9, R′ = H, R″ = Ph 10, R′ = R″ = Me 11, R′ = Me, R″ = Ph 12, R′ = R″ - Ph 13) are presented. Facile insertion of the C=O moiety into the W-H bond was also observed with CO₂ to yield the formato-O-complex trans-W(CMes)(dmpe)₂(OCHO), 8. Reaction of 7 with pyridine-2-carbaldehyde yields the insertion product trans-W(CMes)(η¹-methoxypyridine)(dmpe)₂, 14, but only at temperatures below 0°C. 14 decomposes within minutes at room temperature. Treating 7 with 4-hydroxybenzaldehyde affords trans-W(CMes)(η¹-4-formylphenoxy)(dmpe)₂, 15, via a simple acid-base reaction with concomitant evolution of H₂.

Full text of DOI:10.1021/om000332c

3620
Organometallics 2000, 19, 3620-3630
1,2-Bis(d im eth ylp h osp h in o)eth a n eh yd r id om esitylid yn e-
tu n gsten (IV). Hyd r id e Activa tion via th e Tr a n s In flu en ce
Franck Furno, Thomas Fox, Helmut W. Schmalle, and Heinz Berke*
Anorganisch-chemisches Institut, Universita¨t Zu¨rich, Winterthurerstrasse 190,
CH-8057 Zu¨rich, Switzerland
Received April 18, 2000
The synthesis of the tungsten carbyne hydride complex trans-W(CMes)(dmpe)2H, 7, which
is obtained from the borohydride complex trans-W(CMes)(η1-BH4)(dmpe)2, 6, (dmpe ) Me2-
PCH2CH2PMe2) is reported. 6 is readily prepared from trans-W(CMes)(dmpe)2Cl, 5, which
is prepared from [W(CO)5C(O)Mes][N(CH3)4] via the isolable intermediates trans-W(CMes)-
(CO)2(Py)2Cl, 2, and trans-W(CMes)(CO)[P(OMe)3]3Cl, 3. 7 was spectroscopically fully
characterized, and reactivity studies have revealed its potential in hydrogen transfer
reactions. The results of studies into the reactivity of the W-H bond toward small
unsaturated molecules, such as propionaldehyde, benzaldehyde, acetone, acetophenone, and
benzophenone, to give the corresponding alkoxides trans-W(CMes)(dmpe)2(OCHR′R′′) (R′ )
H, R′′ ) Pr 9, R′ ) H, R′′ ) Ph 10, R′ ) R′′ ) Me 11, R′ ) Me, R′′ ) Ph 12, R′ ) R′′ ) Ph
13) are presented. Facile insertion of the CdO moiety into the W-H bond was also observed
with CO2 to yield the formato-O-complex trans-W(CMes)(dmpe)2(OCHO), 8. Reaction of 7
with pyridine-2-carbaldehyde yields the insertion product trans-W(CMes)(η1-methoxypy-
ridine)(dmpe)2, 14, but only at temperatures below 0 °C. 14 decomposes within minutes at
room temperature. Treating 7 with 4-hydroxybenzaldehyde affords trans-W(CMes)(η1-4-
formylphenoxy)(dmpe)2, 15, via a simple acid-base reaction with concomitant evolution of
H2.
In tr od u ction
tematic investigations have been carried out into how
ancillary ligands might activate the M-H bond. It has
been shown that the nitrosyl ligand plays a significant
role in the electronic activation of a hydride ligand,4
especially those disposed trans to NO. The carbyne
ligand CR (R ) alkyl, aryl) is regarded as a three-
electron donor, and in this sense, it is comparable to
the linear nitrosyl ligand. Of special interest, as with
the nitrosyl ligand, is that the carbyne ligand is also
known to exert a strong trans influence5 on the hydride
and, concomitant with that, significant polarization of
the trans-carbyne disposed W-H bond. The carbyne
moiety is also similar to the NO group in that it is a
good π-acceptor. It is therefore of interest to compare
the reactivity pattern of trans-W(CR)L4H with the
related NO-substituted species trans-W(NO)L4H (L )
phosphorus donor).
The M-H bond plays an important role in organo-
metallic chemistry and in particular in homogeneous
catalysis, where metal hydrides undergo insertion or
hydride transfer reactions with a wide variety of un-
saturated compounds and thus are involved in many
crucial reductive transformations of organic molecules.
However, the M-H bond in many cases appears to be
quite strong and reluctant to undergo the aforemen-
tioned types of reaction. Therefore, it would be of great
general interest to elucidate how ancillary ligands are
able to influence the M-H bond and subsequently
activate it.
In 1973, E. O. Fischer and co-workers1 reported the
first mononuclear carbyne complex. Such complexes
contain one of the strongest metal-ligand π-interactions
in the form of formal MtC triple bond. Since then,
numerous carbyne complexes have been prepared, and
their importance is now well appreciated in organome-
tallic chemistry.2,3
Our CR residue of choice is the sterically demanding
mesityl carbyne ligand, for which, in our case, the
nondesirable nucleophilic attack at the carbyne carbon
has been estimated to be less feasible.6 Furthermore,
electronically an aryl group acts as a π-donor,3 which
lowers the electrophilicity of the carbyne moiety.
Transition metal complexes containing both a hydride
and a carbyne ligand are expected to display unusual
properties. In recent years, our group has studied the
chemistry of activated transition metal hydrides. Sys-
(4) Burger, P.; Berke, H. Comments Inorg. Chem. 1994, 16, 279.
(5) (a) Fee, F. W.; Chan, M. C. W.; Cheung, K. K.; Che, C. M. J .
Organomet. Chem. 1998, 563, 191. (b) Zhang, L.; Gamasa, M. P.;
Gimeno, J .; Carbajo, R. J .; Lopez Ortis, F.; Lanfranchi, M.; Tiripicchio,
A. Organometallics 1996, 15, 4274.
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Angew. Chem. 1973, 85, 618; Angew. Chem., Int. Ed. Engl. 1973, 12,
564.
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79. (b) Schrock, R. R. Science 1983, 219, 13. (c) Green, M. J . Organomet.
Chem. 1986, 300, 93.
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121.
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Shubert, U.; Weiss, K. Carbyne Complexes; VCH: Weinheim, 1988. (b)
Mayr, A.; Hoffmeister, H. Adv. Organomet. Chem. 1991, 32, 227. (c)
Manna, J .; Gilbert, T. M.; Dallinger, R. F.; Geib, S. J .; Hopkins, M. D.
J . Am. Chem. Soc. 1992, 114, 5870.
10.1021/om000332c CCC: $19.00 © 2000 American Chemical Society
Publication on Web 08/03/2000

Hydride Activation via the Trans Influence
Organometallics, Vol. 19, No. 18, 2000 3621
It has been shown that tungsten carbyne hydrides of
the type trans-W(CMes)(CO)nHL4-n (L ) phosphorus
donor) are thermally unstable, probably as a result of
hydride migration and carbene formation.9 Therefore,
to increase the stability of the complexes,1 the replace-
ment of carbonyl ligands by additional phosphorus
donors was sought. Stronger σ-donating phosphines
such as the bidentate dmpe (1,2-bis(dimethylphosphi-
no)ethane) were expected to stabilize our hydride com-
plexes. However, overall we envisaged that there might
be a weakening of the M-H bond, which might exhibit
enhanced reactivity with potential for insertion reac-
tions.6,7
During the formation of 5, it was possible, by 31P NMR
spectroscopy, to detect two intermediate products, 3a
and 4a (Scheme 1).9 3a displays three signals at δ 175.0
ppm (dd, 1J PW ) 460 Hz, P(OMe)3), δ 16.1 ppm (d, 1J PW
1
) 247 Hz, P(trans P(OMe)3), and δ 12.9 ppm (dd, J PW
) 203 Hz, P(trans CO)). 4a shows four signals at δ 20.5
1
1
ppm (dd, J PW ) 257 Hz, P1), δ 7.2 ppm (m, J PW ) 196
Hz, P2), δ -9.5 ppm (m, 1J PW ) 240 Hz, P3), and δ -48.2
ppm (d, P4).
The structure and composition of compound 5 has
been established by IR spectroscopy with the metal-
carbon triple bond stretching mode ν(WtC) at 928 cm-1
in THF solution, by NMR spectroscopy, mass spectrom-
etry, and elemental microanalysis. The mass spectrum
shows the correct isotope pattern for the trans-W(CMes)-
(dmpe)2Cl+ ion. No higher mass peaks were found. The
31P NMR spectrum in toluene-d8 displays a singlet at
23.1 ppm, which corresponds to the four equivalent
phosphorus atoms. This signal shows tungsten satellites
Resu lts a n d Discu ssion
1. Syn th esis of tr a n s-W(CMes)(d m p e)2Cl (5). The
synthetic procedures described in this work are largely
based on chemistry previously outlined by E. O. Fischer
and his group,8 with some modifications used by Mayr,
based on the abstraction of oxide from suitable metal
carbonyl acylates.10
1
with a value for J PW of 282 Hz, in agreement with those
1
previously reported.29 The H and 13C NMR spectra in
toluene-d8 of 5 are also consistent with this formulation.
The only previously reported trans-carbyne hydride
complex with Ht-CR is the trans-W(CCMe3)(dmpe)2H
species,7 which was obtained from the reaction of
W(dmpe)(CH2CMe3)(CHCMe3)(CCMe3) with dmpe at
120 °C for 15 h. However, the preparation of this
compound, as described in the literature, is not suitable
as a general procedure.
We have previously reported the preparation of the
trans-W(CMes)(CO)[P(OMe)3]3Cl (3) complex via a di-
rect reaction of trans-W(CMes)(CO)2(py)2Cl (2) with a
10-fold excess of neat P(OMe)3 in THF at 67 °C for 16
h.9 The synthesis of complex 2 was achieved following
the literature procedure9 (Scheme 1).
Under forcing conditions, it was possible to obtain the
tetrakis(trimethyl phosphite) carbyne complex 4 by
subsequent transformation of complex 3 in excess, neat
P(OMe)3 at 120 °C, which gave 4 in good yield. Although
it was not possible to obtain a satisfactory elemental
analysis for 4, the isolated material was sufficiently pure
to be used in further reactions.
The trimethyl phosphite-substituted complexes 3 and
4 readily undergo substitution of their phosphite ligands.
Reaction of 3 or 4 with 1,2-bis(dimethylphosphino)-
ethane in xylene at 140 °C for 4 days gave the complex
trans-W(CMes)(dmpe)2Cl (5) in yields of 85 and 82%,
respectively, as orange crystals after recrystallization
from dichloromethane/pentane.
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3622 Organometallics, Vol. 19, No. 18, 2000
Furno et al.
Sch em e 1
The 1H NMR spectrum shows four broad signals at 1.55,
1.47, 1.43, and 1.18 ppm corresponding to the two dmpe
ligands. The signal for the mesitylidyne R-carbon is
The bromide analogue of 5 was also isolated from a
Schrock carbyne complex, via a reductive procedure.10
As before, the anionic acyl complex 1 was allowed to
react at low temperature with oxalyl bromide, BrC(O)-
COBr, to give the unstable intermediate trans-halo-
tetracarbonylcarbyne complex, which then reacts with
bromine in the presence of a 10-fold excess of dimeth-
oxyethane (DME) to afford the trihalometalalkylidyne
complex [W(CMes)Br3(dme)] (5a ) as a brown, crystalline
2
found at 260.4 ppm with J CP ) 10 Hz. This low-field
chemical shift is typical for metal carbyne complexes.
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in Sterechemical Analysis; VCH: Weinheim: 1987; Vol. 8.
1
material. H and 13C NMR spectra suggest that 5a is
octahedral with three bromide ligands cis to the mesi-
tylidyne ligand. The 13C NMR spectrum displays a
resonance at δ 324.1 ppm for the mesitylidyne R-carbon.
5a , a Schrock type carbyne tungsten (VI) complex, then
undergoes a two-electron reduction by zinc in the
presence of dmpe in acetonitrile to give complex 5b with
a yield of approximately 36% (Scheme 2).
We have thus shown that both Fischer and Schrock

Hydride Activation via the Trans Influence
Organometallics, Vol. 19, No. 18, 2000 3623
Sch em e 2
Sch em e 3
carried out between -80 and 80 °C, but any fluxionality
in the BH4 moiety was not resolved. The 31P NMR
spectrum displays a singlet at 22.4 ppm for the four
equivalent phosphorus nuclei.9 The signal for the mesi-
2
tylidyne R-carbon is found at δ 266.5 ppm with J CP
)
9 Hz. It was not possible to analyze the 183W nucleus of
6 by indirect NMR spectroscopy, as the W-H-B proton
relaxes too fast, even at low temperature.
We assume that the tetrahydroborate anion adopts a
monodentate coordination mode, as it has already been
observed in our group by a single-crystal X-ray diffrac-
tion study on a similar compound, trans-W(NO)(dmpe)2-
(η1-BH4).14 In the solution IR spectrum of 6 (THF), four
different bands were observed at 927 (m) ν(WtC), 2352
(s) ν(B-Ht), 2035 (s) ν(B-Hb), and 1740 (m br) ν(W-Hb)
.
Compound 6 gave a satisfactory elemental analysis and
the expected mass spectrum. Overall, the structural
features of the η1-BH4 complex remain a rarity among
the versatile bonding modes found for BH4 units.15
Treatment of 6 with 3 equiv of the cyclic amine
quinuclidine in THF at 45 °C for 6 h gave the hydride
7. A strong Lewis base is required to abstract the
borane, and for this, quinuclidine seems to be an ideal
choice, since it does not compete with the phosphorus
donors for coordination to the metal center, but rather
selectively scavenges the BH3.
type carbyne complexes are accessible from the same
starting material.
2. Syn th esis of tr a n s-W(CMes)(d m p e)2H (7). Con-
sidering the preparation of carbyne hydride complexes,
we first isolated the respective borohydride compounds,
since their existence and potential use as synthetic
intermediates were inferred from the earlier carbyne
hydride and the supposedly analogous nitrosyl hydride
chemistry.12
Compound 5 could not directly be transformed into 7
by stoichiometric reaction with LiBH4 or NaBH4 in
diethyl ether at room temperature or in THF at 50 °C.
However, in the latter case reaction of 5 with an excess
of the potential hydride anion donor NaBH4 at 50 °C in
THF for 12 h gave the borohydride complex trans-
W(CMes)(η1-BH4)(dmpe)2, 6. Further reaction of 6 with
quinuclidine (3 equiv) in THF at 45 °C for 6 h then gave
the desired tungsten hydride 7 in good yield (Scheme
3).
An alternative, albeit more expensive, method could
also be employed, using 15 equiv of PMe3 instead of
quinuclidine, in THF for 3 days, at room temperature.
In both cases, thermally stable 7 was isolated in good
yield, 98 and 96% respectively, after recrystallization
from CH2Cl2/pentane. The 1H NMR spectrum in toluene-
d8 at room temperature displays among other charac-
teristic resonances that of the hydride ligand, which
appears as a 1:4:6:4:1 quintet at δ -6.58 ppm (2J HP
)
32 Hz), which has 183W satellite peaks (1J HW ) 32 Hz)
and is quite high field for a tungsten hydride complex.
In fact, this hydride resonance is approaching the values
observed for hydrogen atoms bridging two tungsten
atoms.4 The 31P NMR spectrum displays a singlet at
about δ 25 ppm with tungsten satellites, and the 13C
NMR spectrum shows a charateristic low-field reso-
nance for the carbyne carbon at δ 260.4 ppm (quintet,
2J CP ) 10 Hz). We have also carried out some solid-state
Compound 6 was obtained as brown microcrystals
after recrystallization from diethyl ether at -30 °C in
1
a yield of over 90%. The H NMR spectrum of 6 shows
a broad doublet at δ -2.30 ppm with a characteristic
11B coupling (1J HB ) 80 Hz), which was assigned to the
1
protons of the BH4 group. H NMR spectroscopy was

3624 Organometallics, Vol. 19, No. 18, 2000
Furno et al.
F igu r e 1. (1H, 183W)-HMQC spectrum shown in its magnitude representation (toluene-d8, 298 K).
NMR measurements on 7. Various spinning rates
between 2.0 and 13.5 kHz were used in order to
distinguish between isotropic shifts and rotational side-
bands. As expected from the solid-state structure (vide
infra), the spectrum obtained was quite similar to that
of 1H NMR liquid spectrum, apart from rotational
sidebands. Since the 183W nucleus is relatively abundant
(14% natural abundance), (1H, 183W)-HMQC correlations
have been used to characterize the 183W chemical shift
at δ -1612 ppm (pseudo-quintet, 1J WP ) 281 Hz). It was
also possible to see the coupling with the hydride
hydrogen (Figure 1).
We were able to estimate the degree of ionic bond
character (i) in the covalent M-H bond. This was done
using deuterium NMR spectroscopy, by determining the
DQCC of 2H measuring the T1min relaxation time values
in toluene-d8 solution at different temperatures.16
A
value of i ) 85.0% was obtained. A detailed theoretical
analysis of this phenomenon will be presented else-
where.33 The deuteride analogue of 7 was prepared by
using NaBD4 instead of NaBH4 in the last two steps of
the synthesis to afford the complexes 6a and 7a . As
previously noted by Schrock for trans-W(CCMe3)-
F igu r e 2. X-ray structure of complex 7 (ORTEP repre-
sentation). The hydrogen atoms, except H1, have been
omitted for clarity. Labeling of symmetry-related atoms i
for C3, C4, C6, P1, P2, and C8-C13 is not shown (sym. op.
i ) 1-x, y, 1.5-z).
(dmpe)2H, a W-H or W-D stretching mode in the IR
spectrum is not observed, although many different
solvents have been tried in the search for them.7b,20 The
W-H vibration seems to be of very low IR intensity,
which is quite frequently the case in transition metal
hydride chemistry.13,17 A solid-state Raman spectrum
of 7 displays the W-H vibration at 1600 cm-1. The
position of this band at very low vibrational energies
allows us to suggest that the W-H bond of 7 seems to
be relatively weak. The WtC vibration was found at
about 920 cm-1, which is consistent with those reported
by Hopkins and co-workers.18
(30) (a) Immirzi, A.; Musco, A. Inorg. Chim. Acta 1977, 22, L35. (b)
Darensbourg, D. J .; Day, C. S.; Fischer, M. B. Inorg. Chem. 1981, 20,
3577. (c) Grove, D. M.; Van Koten, G.; Ubbels, H. J . C.; Zoet, R.; Spek,
A. L. J . Organomet. Chem. 1984, 263, C10. (d) Bianchini, C.; Ghilardi,
C. A.; Meli, A.; Midollini, S.; Orlandini, A. Inorg. Chem. 1985, 24, 924.
(e) Darensbourg, D. J .; Pala, M. J . J . Am. Chem. Soc. 1985, 107, 5687.
(f) Fong, L. K.; Fox, J . R.; Cooper, N. J . Organometallics 1987, 6, 223.
(g) Tsai, J .-C.; Nicholas, K. M. J . Am. Chem. Soc. 1992, 114, 5117.
(31) (a) Burt, R. J .; Chatt, J .; Hussain, W.; Leigh, G. J . J . Organomet.
Chem. 1979, 182, 203. (b) Parschall, G. W. J . Inorg. Nucl. Chem. 1960,
14, 291. (c) Wolfsberger, W.; Schmidbaur, H. Synth. React. Inorg. Met.
Org. Chem. 1974, 4, 149. (d) Zingaro, R. A.; McGlothlin, R. F. J . Chem.
Eng. Data 1963, 8, 226.
(32) Gordon, A. J .; Ford, R. A. The Chemist’s Companion; Wiley:
New York, 1972.
(33) J acobsen, H.; Furno, F.; Berke, H. Manuscript in preparation.
The structure of this trans-mesitylidyne hydride

Hydride Activation via the Trans Influence
Organometallics, Vol. 19, No. 18, 2000 3625
The 1H NMR spectrum of 8 displays a singlet at δ
8.25 ppm, which is assigned to the formate proton, and
the 13C NMR spectrum shows a singlet resonance at δ
165.9 ppm, attributed to the formate carbon. On heating
a solution of 8 to +50 °C, no signal was observed
corresponding to an η2-CO2 insertion product. The THF
solution IR spectrum of 8 exhibits two bands at 1621
and 1337 cm-1 for the formate ligand, in accordance
with other reported η1-formate complexes in the litera-
ture.30f,g 8 has been further characterized by elemental
analyses and mass spectrometry. Formate, like most
carboxylate ligands, tends to be a bis(chelate) or bridg-
ing ligand, and relatively few η1-formate complexes have
been characterized to date.30 Here we present the
structure of 8, which has been studied by single-crystal
X-ray diffraction (Figure 3). Suitable crystals were
obtained by slow cooling of a saturated diethyl ether
solution to -30 °C. Selected bond distances (Å) and bond
angles (deg) are listed in Table 2.
The tungsten center adopts a pseudooctahedral ge-
ometry, with the carbyne and the η1-formate ligands
trans to each other. This X-ray structure indicates a
W-O(1) distance of 2.275(10) Å and a W-O(2) distance
of about 3.63(1) Å, which is unambiguously nonbonding.
These two W-O bond lengths are consistent with most
(but not all30d,e) of the reported η1-formate structures,
with the conventional bonding description (W-O-CHd
O). The other geometric parameters are quite similar
to those of compound bis(formate)[Mo(dmpe)2(OCHO)2],30f
except for the angles P(n)-W-O(1) (n ) 1-4), which
are about 5° smaller in 8, probably due to the trans
sterically large carbyne ligand. The C(1)-W-O(1) angle
(175.7(4)°) also deviates from an ideal value.
Ta ble 1. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) in tr a n s-W(CMes)(d m p e)2Ha
selected bond distances (Å)
selected angles (deg)
W(1)-C(1) 1.863(6)
W(1)-H(1) 2.0088
C(1)-C(2) 1.448(9)
W(1)-P(1) 2.4281(14)
W(1)-P(2) 2.4208(15)
W(1)-P(1i) 2.4281(14)
W(1)-P(2i) 2.4208(15)
W(1)-C(1)-C(2) 180.0
H(1)-W(1)-C(1) 180.0
P(1)-W(1)-P(2) 81.07(5)
P(1)-W(1)-P(2i) 81.07(5)
P(1)-W(1)-H(1) 81.64(3)
P(1i)-W(1)-H(1) 81.64(3)
P(2)-W(1)-H(1) 77.39(4)
P(2i)-W(1)-H(1) 77.39(4)
P(1i)-W(1)-P(1) 163.28(7)
C(1)-W(1)-P(2) 102.61(4)
C(1)-W(1)-P(1) 98.36(3)
P(1)-W(1)-P(2i) 95.26(5)
a
See Figure 2 for atom designations. Symmetry operator for i
) 1-x, y, 1.5-z.
complex 7 was finally unequivocally established by a
single-crystal X-ray diffraction study (Figure 2). Suitable
crystals were obtained by slow cooling of a saturated
CH2Cl2/pentane solution to -30 °C. Selected bond
distances (Å) and bond angles (deg) are listed in Table
1.
7 adopts a pseudooctahedral geometry with the two
dmpe ligands in equatorial positions and the hydride
and carbyne ligands axial and trans to each other. This
type of structure has previously been observed for
similar M(CR)L4X complexes (M) Cr, Mo, W; L )
phosphorus donor).6 This X-ray structure indicates a
W-H bond of about 2 Å; this distance has to be taken
with caution, but it is significantly longer than expected
on the basis of previous X-ray crystallographic studies
(around 1.8 Å).21 However, this could be due to a strong
trans-influence of the carbyne ligand. The strong σ-do-
nor dmpe ligands may also contribute to this elongation
and as a result increase the “hydridic” character of H;
that is, greater separation of charge across M-H bond
(less covalent, more ionic) occurs. The tungsten carbon
triple bond distance is about 1.86 Å, which is unremark-
able and similar to those calculated22 or observed in the
literature.5b,6,23
Aldehydes and ketones have been shown in our
laboratory to insert directly into the W-H bond of
trans,trans-W(H)(CO)2(NO)(PMe3)2, trans-W(H)(CO)-
(NO)(PMe3)3, and with their analogous Mo com-
plexes,13,21,24 apparently without prior coordination of
the substrate to the metal, via a mechanism involving
direct nucleophilic attack of the hydride ligand at the
electrophilic carbon of the aldehyde or ketone. The
reactions of 7 demonstrate this conclusively, since it
cannot easily be envisaged that 7 provides an open
coordination site.
The dmpe ligands do not lie exactly in the equatorial
plane but are bent away from the carbyne unit, presum-
ably due to unfavorable steric interactions between the
mesityl ortho-methyl groups and the methyl groups
attached to phosphorus.
Treatment of 7 with 1 equiv of propionaldehyde or
benzaldehyde affords the corresponding alkoxy com-
pounds (Scheme 4).
3. Reactivity P atter n s of tr a n s-W(CMes)(dm pe)2H
(7). Compound 7 was expected to undergo facile inter-
molecular hydride transfer reactions, i.e., insertions
with a wide variety of unsaturated compounds such as
CO2, aldehydes, ketones, and metal carbonyls, to afford
principally compounds with W-O bonds. Aldehydes and
ketones have only rarely been demonstrated to insert
into transition metal hydrogen bonds,24 with ketones
being particularly reluctant to undergo such transfor-
mations. These types of insertions, however, have been
invoked as key steps in catalytic reduction with transi-
tion metal compounds.25 Insertion of CO2 into a metal
hydride bond is a reaction of growing interest,19 since
it is assumed to be the initial step in the hydrogenation
of CO2.26 7 reacts readily with 1 bar of CO2 in THF to
give the η1-formate species 8. The reaction was complete
after a few minutes at -25 °C. This complex was
isolated in 85% yield as analytically pure orange crystals
after recrystallization from diethyl ether (Scheme 4).
When the reactions were monitored by 1H NMR
spectroscopy in toluene-d8, a triplet at δ 3.21 ppm (3J HH
) 6.3 Hz) and a singlet at δ 4.23 ppm indicated the
formation of the insertion products trans-W(CMes)(η1-
OPr)(dmpe)2, 9, and trans-W(CMes)(η1-OBn)(dmpe)2, 10,
respectively. Compounds 9 and 10 were isolated with
yields of 90 and 97%, respectively, after recrystallization
from CH2Cl2/pentane at -30 °C, and their compositions
confirmed by elemental microanalyses.
Reactions of the W-H bond of 7 with ketones were
slower. Reduction of these unsaturated compounds were
spectroscopically observable by NMR spectroscopy after
a few minutes, but the reactions were complete only
after 36-48 h, at 60 °C (Scheme 4).
Treatment of 7 with 1 equiv of acetophenone or
benzophenone from room temperature up to 60 °C
yielded 12 and 13, respectively. Compound 12 shows a

3626 Organometallics, Vol. 19, No. 18, 2000
Furno et al.
Sch em e 4
quartet at δ 4.17 ppm for the OCHMePh proton (3J HH
) 6 Hz) and a characteristic signal at δ 77.7 ppm in
the 13C NMR spectrum which is attributed to the
W-OCHMePh carbon. 13 displays chemical shifts simi-
NMR spectra, respectively. The compositions of 12 and
13 were further confirmed by elemental microanalyses.
Acetone is known to be a more reluctant reagent
compared to acetophenone or benzophenone, so a higher
stoichiometric ratio (1:2) was used. The phenyl sub-
1
lar to 12 at δ 5.08 and δ 86.7 ppm in the H and 13C
Ta ble 2. Selected Bon d Len gth s (Å) a n d Bon d
a
An gles (d eg) in tr a n s-W(CMes)(η1-OC(O)H)(d m p e)2
selected bond distances (Å)
selected angles (deg)
W(1)-C(1) 1.821(14)
W(1)-O(1) 2.275(10)
C(1)-C(2) 1.457(9)
W(1)-P(1) 2.441(4)
W(1)-P(2) 2.463(3)
W(1)-P(3) 2.463(4)
W(1)-P(4) 2.456(3)
O(1)-C(11) 1.227(19)
C(11)-O(2) 1.24(2)
C(11)-H(11) 0.95
W(1)-C(1)-C(2) 178.6(10)
C(1)-W(1)-O(1) 175.7(4)
P(1)-W(1)-P(2) 80.87(12)
P(3)-W(1)-P(2) 97.51(12)
P(4)-W(1)-P(2) 166.24(13)
P(4)-W(1)-P(3) 81.51(13)
P(1)-W(1)-P(3) 169.97(14)
P(1)-W(1)-P(4) 97.69(13)
C(1)-W(1)-P(1) 95.7(4)
C(1)-W(1)-P(4) 93.9(4)
C(1)-W(1)-P(3) 94.3(4)
C(1)-W(1)-P(2) 99.8(4)
O(1)-W(1)-P(1) 80.8(3)
O(1)-W(1)-P(4) 89.1(3)
O(1)-W(1)-P(3) 89.2(3)
O(1)-W(1)-P(2) 77.2(3)
C(11)-O(1)-W(1) 135.0(11)
O(1)-C(11)-O(2) 126.7(18)
O(1)-C(11)-H(11) 116.7
O(2)-C(11)-H(11) 116.7
C(2)-C(3) 1.433(19)
W(1)-O(2) 3.63(1)
F igu r e 3. X-ray structure of complex 8 (ORTEP repre-
sentation). The hydrogen atoms of the mesitylidyne and
the dmpe ligands have been omitted for clarity.
a
See Figure 3 for atom designations.

Hydride Activation via the Trans Influence
Organometallics, Vol. 19, No. 18, 2000 3627
stituent apparently facilitates these reactions via en-
hanced electrophilicity of the Ccarbonyl atom. This was
confirmed qualitatively by the apparently longer reac-
tion time with acetone. Hence, 7 with 2 equiv of acetone
at 60 °C gave compound 11 in almost spectroscopically
quantitative yield after 2 days. At room temperature,
however, even after stirring 10 days and with the
addition of up to 5 equiv of acetone, the spectroscopic
yield of compound 11 was only about 60%. The structure
of 11 was assigned on the basis of NMR spectroscopy
and its composition confirmed by mass spectrometry.
1
(2)
The H NMR spectrum of 11 shows a septet at δ 3.56
ppm for the OCHMe2 proton and a signal at δ 78.7 ppm
in 13C NMR spectrum, which is attributed to the
W-OCHMe2 carbon.
All the alkoxy compounds produced were found to be
relatively stable and could be stored at low temperature
(-30 °C) for several months or at room temperature for
a few days before decomposing. We have also studied
the reactivity of 7 toward modified aldehydes, i.e.,
aldehydes that contain an additional functional group.
Reaction of 7 with 1 equiv of pyridine-2-carbaldehyde
(eq 1) leads to the corresponding alkoxy compound 14.
However, in contrast to trans-W(CMes)(CO)H-
[P(OMe)3]3,9 trans-W(CMes)(dmpe)2H does not react
readily with donor molecules such as acetonitrile, tri-
methylphosphine, and trimethyl phosphite, even in the
presence of a large excess of these reagents. Further-
more, reaction of 7 with camphor was not successful
either, probably due to steric factors.
The insertion of carbon monoxide into a M-H bond
to produce a formyl species has been proposed as a key
step in the homogeneous catalytic hydrogenation of
CO.27 However, the direct product of CO insertion into
a M-H bond, a metal-bound formyl group, is rarely
observed28 and generally requires either a strongly
hydridic hydride or the presence of a Lewis acidic group,
presumably due to the high bond energy of CO. The
reaction of 7 with an excess of CO (1 bar), in toluene-
d8, from room temperature up to +50 °C was monitored
in a sealed NMR tube experiment over a period of
several days. However, after a few days, only decom-
position was observed, and no metal-containing product
could be traced. The main problem seems here to be the
low CO solubility in common solvents.
(1)
2D NMR experiments such as long-range coupling
{1H, 13C} (LR-CH), HSQC {1H, 13C}, and NOESY {1H,
1H} were performed at 500 MHz (at -40 °C to confirm
a W-O bond rather than a W-N bond as already seen
in our group).24b However, attemps to isolate 14 were
unsuccessful due to its rapid decomposition at room
temperature.
In some cases, when the carbonyl substrate contains
an acidic functionality, 7 reacts via an acid-base
reaction rather than by hydride transfer. For example,
7 reacts with 1 equiv of 4-hydroxybenzaldehyde at room
temperature in toluene, and no reduced organic prod-
ucts were observed. The hydride complex acts as a base
toward the acidic alcoholic hydrogen of the reagent to
give 15 (eq 2).
Con clu sion
The tungsten carbyne hydride complex 7 has been
prepared and its reactivity toward unsaturated organic
molecules studied. Support for the enhanced hydricity
and weakness of the W-H bond is indeed provided by
physical and chemical evidence. We have also synthe-
sized the isoelectronic analogous nitrosyl complex of 7,
and we are currently comparing the physical properties
and the reactions based on the trans-influence/effect of
the linear nitrosyl and the carbyne ligands, which both
are three-electron donor ligands.
Exp er im en ta l Section
All manipulations of air-sensitive compounds were carried
out either in a dry glovebox under recirculating nitrogen or
under dry nitrogen by conventional Schlenk techniques.
Solvents were distilled from appropriate drying agents32 and
freshly distilled under nitrogen prior to use (e.g., diethyl ether,
hexane, pentane, benzene, toluene, xylene, 1,2-dimethoxy-
ethane, and THF were purified by reflux over sodium/ben-
zophenone, dichloromethane was refluxed either over calcium
This complex presumably results from protonation of
the transition metal complex and subsequent loss of
dihydrogen. The evolution of H2 can also be traced in
1
the H NMR spectrum with the H2 resonance at about
δ 4.25 ppm. The formation of this compound thus
confirms the substantial hydridic character of the W-H
functionality in 7.

3628 Organometallics, Vol. 19, No. 18, 2000
Furno et al.
Ta ble 3. Cr ysta ls Da ta a n d Str u ctu r e Refin em en t
P a r a m eter s for 7 a n d 8
hydride or over P2O5, pyridine was dried over KOH pellets).
Quinuclidine, benzophenone, acetophenone, 4-hydroxybenz-
aldehyde, and 2-pyridine carbaldehyde were dried a few hours
under high vacuum. The deuterated solvents (C6D6, CDCl3,
toluene-d8, and THF-d8) were also obtained from commercial
suppliers and distilled from appropriate drying agents and
vacuum transferred for storage in Schlenk flasks fitted with
Teflon stopcocks. The ligands dmpe and PMe3 were synthe-
sized following modified literature procedures,31 whereas all
other reagents were purchased and used without further
purification. 1H, 13C, 31P, and 11B NMR spectra were run either
on a Varian Gemini-300 operating at 300.1, 75.4, 121.5, and
96.2 MHz, respectively, or on a Bruker DRX-500 spectrometer
at 500.2, 125.8, 202.5, and 160.5 MHz, respectively. δ(1H),
δ(13C), rel. to SiMe4, δ(31P) rel. to 85% H3PO4, δ(11B) rel. to
BF3/OEt2, and δ(183W) rel. to Na2WO4. All solid-state NMR
measurements have been carried out at room temperature
using a small bore probe for 4 mm rotors. The 31P and 13C
spectra were obtained under CP-MAS conditions and high-
power proton decoupling during acquisition. Various spinning
rates between 2.0 and 13.5 kHz were used in order to
distinguish between isotropic shifts and rotation sidebands.
Mass spectra (EI or FAB) were recorded on a Finnigan MAT-
8230 mass spectrometer. IR spectra: Bio-Rad FTS-45 instru-
ment. Raman spectra: Renishaw Labram Raman microscope.
Elemental analyses: LECO CHNS-932
7
8
formula
Mr
C
22H44P4W
C23H44O2P4W
660.31
616.30
cryst habit
red plate
single crystal
orange plate
single crystal
0.35 × 0.22 × 0.12
monoclinic
P21/c
9.1712(7)
8.9647(5)
33.982(3)
90
94.231(10)
90
2786.3(4)
1.574
cryst size (mm)
cryst syst
space group
a (Å)
b (Å)
c (Å)
0.30 × 0.30 × 0.11
monoclinic
C2/c
12.8920(10)
12.5780(9)
16.9976(14)
90
97.424(9)
90
2733.2(4)
1.498
R (deg)
â (deg)
γ (deg)
V (Å3)
F
calc (g cm-3
)
Z
4
4
F(000)
temp (K)
1240
173(2)
44.67
1328
183(2)
43.93
µ (cm-1
)
abs corr
min/Tmax (°C)
θ range (deg)
hkl range
numerical
0.3746/0.6393
3.16-30.32
-18 < h <17
-17 < k <17
-24 < l <24
14 195
3831
3377
133
numerical
0.3086/0.6207
2.23-24.63
-10 < h <10
-10 < k <10
0 < l <39
8847
4675
3969
282
T
Compounds 1, 2, 3, and 4 were prepared following earlier
procedures,9 and the observed spectroscopic data were in
accordance with those reported.
Cr ysta llogr a p h y. Compound 7 crystallized as red plates
in the monoclinic space group, C2/c with unit cell parameters
of a ) 12.8920(10) Å, b ) 12.5780(9) Å, c ) 16.9976(14) Å, â
) 97.424(9)°, V ) 2733.2(4) Å3, Z ) 4, and R ) 0.0463 for 3377
observed reflections.
no. of data measd
no. of unique data
no. of data obsda
no. of params
max. shift/esd
0.001
+4.302, -2.723
0.0463
0.001
+1.881, -2.991
0.0672
resd dens (e Å-3
R1 (obs)
)
wR2 (obs)
GooF
0.1229
1.121
0.1527
1.446
Compound 8 crystallizes as red plates in the monoclinic
space group P21/c with unit cell parameters of a ) 9.1712(7)
Å, b ) 8.9647(5) Å, c ) 33.982(3) Å, â ) 94.231(10)°, V )
2786.3(4) Å3, Z ) 4, and R ) 0.0672 for 3969 observed
reflections.
a
With Iobs g 2σ(I).
residual electron density maximum near the tungsten atom
during refinement stage, but the isotropic displacement pa-
rameter was freely refined, resulting in the acceptable value
of 0.07(4) Å2.
Single crystals of 7 and 8 were mounted on top of a glass
fiber using perfluoropolyether oil and immediatly transferred
to the diffractometer where the crystals were cooled to 173 K
(7) and 183 K (8) by an Oxford cryo system. The determination
of the unit cell parameters and the collection of intensity data
were performed with an image plate detector system (Stoe
IPDS diffractometer) using the Stoe IPDS software, Version
No. 2.90 (1998).34 The crystal of 7 showed relatively weak
diffraction power; hence the irradiation time was augmented
to 9 min per image. The crystal-to-image distance for crystal
7 could be set to 50 mm (resulting in θmax ) 30.3°), whereas
for crystal 8 the respective distance had to be set to 76 mm
(θmax ) 24.6°) due to a long cell axis and therefore prevent
overlap of neighboring reflections. Lorentz and polarization
corrections were done with INTEGRATE; numerical absorp-
tion corrections35 were performed with XRED, using 13 (for
7) and 14 (for 8) measured and indexed crystal faces using a
video camera installed at the IPDS diffractometer. Both
structures were solved with direct methods using SHELXS-
97.36 The refinements were performed with SHELXL-97.37
In 7, the hydride hydrogen was finally found by difference
electron density calculations near the 2-axis. The x and z
coordinates were shifted to the special position x ) 0.50 and z
) 0.75, resulting in a distance of about 2.0 Å from the tungsten
atom. The y coordinate of the hydride approached the main
The thermal ellipsoids in the ORTEP drawings of Figures
2 and 3 are drawn at the 30% probability level. Additional
information on the data collection and refinement parameters
for 7 and 8 are given in Table 3.
P r ep a r a tion of W(CMes)(d m e)Br 3 (5a ). A methylene
chloride solution (50 mL) containing the pentacarbonylmetal
acylate complex 1 (2 g, 3.67 mmol) is cooled to -95 °C (CH2-
Cl2/liquid N2), and a cold (-95 °C) solution of oxalyl bromide
(0.41 mL, 4.40 mmol) is added. The solution is warmed to -20
°C and stirred at that temperature for 1 h, then cooled again
at -70 °C. In succession, a 10-fold excess of DME and a cold
CH2Cl2 solution (-70 °C) of an equivalent amount of bromine
are added. The resulting deep orange-brown solution is then
warmed to room temperature. The solvent is removed in vacuo,
and the filtrate is redissolved in methylene chloride, filtered
over a layer of Celite, and recrystallized in CH2Cl2/pentane to
1
afford brown microcrystals of 5a (2.20 mmol, yield: 60%). H
NMR (C6D6, 298 K): δ 6.62 (s, 2H, Mes), 2.80 (s, 6H, 2CH3-
Mes), 3.60 and 3.18 (s, 6H, MeOCH2CH2OMe), 3.00 and 2.89
(m, 4H, MeOCH2CH2OMe), 1.98 (s, 3H, CH3-Mes). 13C{1H}
NMR (C6D6, 298 K): δ 324.1 (m, CMes), 148.2 (s, ipso-Mes),
141.1 (s, o-Mes), 135.2 (s, p-Mes), 127.8 (s, m-Mes), 76.7 (s,
MeOCH2CH2OMe), 75.5 (s, MeOCH2CH2OMe), 68.8 (s, Me-
OCH2CH2OMe), 58.7 (s, MeOCH2CH2OMe), 21.3 (s, 2CH3-
Mes), 20.1 (s, CH3-Mes).
(34) Stoe & Cie. IPDS Software, Version 2.90; Stoe &Cie: Darm-
stadt, Germany, 1998.
(35) Coppens, P.; Leiserowitz, L.; Rabinovich, D. Acta Crystallogr.
1965, 18, 1035.
(36) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.
(37) Sheldrick, G. M. SHELX97; University of Go¨ttingen: Germany,
1997.
P r ep a r a tion of tr a n s-W(CMes)(d m p e)2Cl (5). Compound
3 (3.0 g, 4.0 mmol) was dissolved in xylene (150 mL), and dmpe
(1.5 mL, 8.79 mmol, 2.2 equiv) was added. The resulting
mixture was refluxed at 140 °C for 4 days. The solution became
red and was then cooled to room temperature. The solvent was

Hydride Activation via the Trans Influence
Organometallics, Vol. 19, No. 18, 2000 3629
1
removed in vacuo and the resulting precipitate dissolved in
n-hexane at 0 °C, then filtered through a layer of Celite. After
removal of the solvent, drying under dynamic vacuum, and
recrystallization in CH2Cl2/hexane, 2.21 g of 5 (3.4 mmol, 85%)
was obtained as orange crystals.
of the hydride 7 (1.53 mmol, 96%). H NMR (C6D6, 298 K): δ
6.72 (s, 2H, Mes), 2.62 (s, 6H, 2CH3-Mes), 2.05 (s, 3H, CH3-
Mes), 1.67 (s br, 12H, PMe), 1.52 (m br, 4H, PCH2), 1.46 (s br,
12H, PMe′), 1.42 (m br, 4H, PCH2′), -6.58 (q, 1H, 2J HP ) 32.10
Hz, J HW ) 31.50 Hz, WH). 31P{1H} NMR (C6D6, 298 K): δ
1
24.4 (s, J PW ) 281 Hz). 13C{1H} NMR (C6D6, 298 K): δ 260.4
1
Alternative method: to a stirred solution of 5a (1.0 g, 1.59
mmol) in acetonitrile were added dmpe (0.60 mL, 3.5 mmol)
and a large excess of zinc. After 24 h at 25 °C, the organic
phase was decanted and reduced to dryness under vacuum.
The remaining solid was extracted with CH2Cl2 and the extract
filtered, concentrated, and recrystallized in CH2Cl2/hexane,
giving 5b (0.95 mmol, 60%). 1H NMR (toluene-d8, 298 K): δ
6.60 (s, 2H, Mes), 2.50 (s, 6H, 2CH3-Mes), 1.97 (s, 3H, CH3-
Mes), 1.55 (br, 4H, PCH2), 1.47 (s br, 12H, PMe), 1.43 (s br,
12H, PMe′), 1.18 (br, 4H, PCH2′). 31P{1H} NMR (toluene-d8,
2
(q, J CP ) 10 Hz, CMes), 151.5 (s, ipso-Mes), 137.4 (s, o-Mes),
135.4 (s, p-Mes), 130.8 (s, m-Mes), 34.0 (q, PCH2), 27.8 (m,
PMe), 25.4 (m, PMe′), 22.6 (s, 2CH3-Mes), 21.5 (s, CH3-Mes).
183W {1H} NMR (toluene-d8, 298 K: δ -1612 (pseudo-q, J WP
1
) 281 Hz). MS (FAB, toluene): m/e 615 (M+), 310 (M+
-
2dmpe). Anal. Calcd for WC22H44P4 (615.73): W, 29.86; C,
42.87; H, 7.15. Found: W, 29.26; C, 42.67; H, 7.28.
P r ep a r a tion of tr a n s-W(CMes)(d m p e)2(D) (7a ). Com-
pound 7a was prepared in analogous fashion to compound 7,
utilizing 0.1 g (0.16 mmol) of compound 6a , 0.05 g (0.45 mmol)
of quinuclidine, and 30 mL of THF. Recrystallization in CH2-
Cl2/pentane afforded 0.07 g of 7a (0.11 mmol, 70%) as red
crystals. 2D NMR (toluene-d8, 183 K): δ -6.60 (m br, WD).
P r ep a r a tion of tr a n s-W(CMes)(η1-OC(O)H)(d m p e)2 (8).
A red solution of the hydride 7 (50 mg, 0.08 mmol) in THF (15
mL) was stirred under 1 bar of carbon dioxide for 30 min at
-25 °C. The solution became immediately bright orange. The
resulting mixture was then allowed to warm to room temper-
ature, and the solvent and excess CO2 were rapidly removed
under high vacuum. The residue was washed three times with
pentane (3 × 10 mL) to afford after recrystallization in diethyl
ether 53.6 mg of the η1-formate complex 8 (0.068 mmol, 85%)
as orange crystals. 1H NMR (toluene-d8, 298 K): δ 8.25 (s, 1H,
OC(O)H), 6.56 (s, 2H, Mes), 2.50 (s, 6H, 2CH3-Mes), 1.96 (s,
3H, CH3-Mes), 1.60 (s br, 12H, PMe), 1.43 (m br, 4H, PCH2),
1.30 (s br, 12H, PMe′), 1.27 (m br, 4H, PCH2′). 31P{1H} NMR
1
298 K): δ 23.12 (s, J pw ) 282 Hz). 13C{1H} NMR (toluene-d8,
2
298 K): δ 260.4 (q, J cp ) 10 Hz, CMes), 147.9 (s, ipso-Mes),
136.1 (s, o-Mes), 132.2 (s, p-Mes), 128.0 (s, m-Mes), 33.7 (q,
PCH2), 23.1 (s, 2CH3-Mes), 22.4 (q, PMe), 21.3 (s, CH3-Mes),
18.2 (q, PMe′). IR (THF, cm-1): νWtC 928 (m). MS (FAB, CH2-
Cl2): m/e 650 (M+), 500 (M+ - dmpe), 390 (M+ - dmpe - Mes).
Anal. Calcd for WC22H43P4Cl (650.18): W, 28.27; C, 40.60; H,
6.61. Found: W, 28.20; C, 40.74; H, 6.33.
P r ep a r a tion of tr a n s-W(CMes)(η1-HBH3)(d m p e)2 (6).
Compound 5 (2.0 g, 3.08 mmol) was dissolved in THF (50 mL)
and NaBH4 (0.35 g, 9.23 mmol) added. The resulting mixture
was warmed to 55 °C and stirred at this temperature for 12
h; then the solvent was removed in vacuo, and the precipitate
redissolved in benzene. After filtration over Celite, the solvent
was again removed in vacuo, and the precipitate was washed
with pentane (3 × 20 mL) and recrystallized in CH2Cl2/pentane
to afford 1.9 g of 6 (3.02 mmol, 98%) as brown microcrystals.
1H NMR (THF-d8, 298 K): δ 6.70 (s, 2H, Mes), 2.52 (s, 6H,
2CH3-Mes), 1.99 (s, 3H, CH3-Mes), 1.77 (br, 4H, PCH2), 1.67
(s br, 12H, PMe), 1.38 (s br, 12H, PMe′), 1.20 (br, 4H, PCH2′),
-2.30 (d br, HBH3). 31P{1H} NMR (THF-d8, 298 K): δ 22.4 (s,
1J PW ) 281 Hz). 13C{1H} NMR (THF-d8, 298 K): δ 266.5 (q,
2J CP ) 9 Hz, CMes), 148.0 (s, ipso-Mes), 136.2 (s, o-Mes), 133.3
(s, p-Mes), 128.2 (s, m-Mes), 34.0 (q, PCH2), 23.4 (m, PMe),
22.8 (s, 2CH3-Mes), 21.3 (s, CH3-Mes), 20.7 (q, PMe′). IR (THF,
cm-1): νWtC 927 (m), νB-Ht 2352 (s), νB-Hb 2035 (s), νW-Hb 1740
(m br). MS (FAB, toluene): m/e 630 (M+), 615 (M+ - BH4), 310
(M+ - BH4 - 2dmpe). Anal. Calcd for WC22H47P4B (629.54):
C, 41.93; H, 7.47. Found: C, 42.30; H, 7.61.
P r ep a r a tion of tr a n s-W(CMes)(η1-DBD3)(d m p e)2 (6a ).
Compound 6a was prepared in an analogous fashion to
compound 6, utilizing 0.2 g (0.31 mmol) of compound 5, 0.03 g
(0.72 mmol) of NaBD4, and 50 mL of THF. Recrystallization
in CH2Cl2/pentane afforded 0.18 g of 6a (0.28 mmol, 90%) as
brown microcrystals. This compound closely resembles 6 in
its spectroscopic properties. 2D NMR (toluene-d8, 293 K):
δ-2.65 (s br, DBD3). 11B NMR (toluene-d8, 293 K): δ -2.3 (s
br, DBD3).
(toluene-d8, 298 K): δ 31.3 (s, J PW ) 286 Hz). 13C{1H} NMR
(toluene-d8, 298 K): δ 263.4 (q, J CP ) 9 Hz, CMes), 165.9 (s,
1
2
OC(O)H), 147.8 (s, ipso-Mes), 137.4 (s, o-Mes), 135.2 (s, p-Mes),
131.5 (s, m-Mes), 33.4 (m, PCH2), 30.1 (m, PMe), 25.0 (s, 2CH3-
Mes), 22.7 (m, PMe′), 21.1 (s, CH3-Mes). IR (THF, cm-1): νWt
921 (m); ν(OCO) 1962, 1621. MS (FAB, CH2Cl2): m/e 660 (M+),
C
615 (M+ - CO2H), 510 (M+ - dmpe). Anal. Calcd for
WC23H44P4O2 (659.73): C, 41.83; H, 6.67. Found: C, 41.83; H,
6.75.
P r epar ation of tr a n s-W(CMes)(η1-OP r )(dm pe)2 (9). Com-
pound 7 (30 mg, 0.0487 mmol) was dissolved in toluene (5 mL)
and propionaldehyde (3.54 µL, 0.0487 mmol) added by mi-
crosyringe at room temperature. The red solution became
immediately orange. After a few minutes, the solvent was
removed in vacuo and the precipitate recrystallized in CH2-
Cl2/pentane at -30 °C to afford 9. Yield: 27 mg (90%). 1H NMR
(toluene-d8, 298 K): δ 6.74 (s, 2H, Mes), 3.21 (t, 2H, O-CH2),
2.62 (s, 2CH3-Mes), 2.07 (s, CH3-Mes), 1.54 (s br, 12H, PMe),
1.48 (m br, 4H, PCH2), 1.37 (s br, 12H, PMe′), 1.33 (m br, 4H,
PCH2′). 31P{1H} NMR (toluene-d8, 298 K): δ 25.3 (s, J PW
)
)
1
288 Hz). 13C{1H} NMR (toluene-d8, 298 K): δ 247.6 (q, J CP
2
9 Hz, CMes), 149.2 (s, ipso-Mes), 136.0 (s, o-Mes), 130.4 (s,
p-Mes), 128.0 (s, m-Mes), 73.2 (s br, O-CH2), 33.5 (q, PCH2),
23.0 (s, 2CH3-Mes), 22.5 (m, PMe), 21.2 (s, CH3-Mes), 18.1 (m,
P r ep a r a tion of tr a n s-W(CMes)(d m p e)2(H) (7). Com-
pound 6 (1.0 g, 1.59 mmol) was dissolved in THF (30 mL), and
quinuclidine (0.53 g, 4.76 mmol) was added. The resulting
mixture was stirred 3 h at 30 °C and then 3 h at 45 °C. The
solvent was removed in vacuo, and the precipitate redissolved
in n-hexane. After filtration over Celite, the solvent and excess
quinuclidine were removed in vacuo for 4 h at 50 °C, to afford
after recrystallization in CH2Cl2/pentane 0.96 g of the hydride
7 (1.56 mmol, 98%) as red crystals.
An alternative method could be employed, using 1.0 g (1.59
mmol) of 6 in THF (30 mL) and 2.46 mL of PMe3 (23.85 mmol,
15 equiv), instead of quinuclidine. The resulting mixture was
stirred 3 days at room temperature. The solvent and the
byproduct Me3PBH3 were removed by sublimation under
dynamic vacuum at 50 °C for 2 h. The solid was dissolved in
benzene and filtered over Celite. Removal of the solvent from
the filtrate and then washing the solid with pentane (3 × 20
mL) afforded after recrystallization in CH2Cl2/pentane 0.94 g
PMe′). MS (EI): m/e 674 (M+), 616 (M+ - OPr), 523 (M+
-
dmpe). Anal. Calcd for WC25H50P4O (673.73): C, 44.53; H, 7.42.
Found: C, 44.48; H, 7.03.
P r ep a r a tion of tr a n s-W(CMes)(η1-OBn )(d m p e)2 (10).
Compound 7 (30 mg, 0.0487 mmol) was dissolved in toluene
(5 mL) and benzaldehyde (5.0 µL, 0.0487 mmol) added by
microsyringe at room temperature. An immediate color change
from red to orange was observed. After a few minutes, the
solvent was removed in vacuo and the precipitate recrystal-
lized in CH2Cl2/pentane at -30 °C to afford 10. Yield: 29 mg
1
(97%). H NMR (toluene-d8, 298 K): δ 7.39 (d, 2H, o-benzal.),
7.13 (d, 1H, p-benzal.), 6.96 (m, 2H, m-benzal.), 6.60 (s, 2H,
Mes), 4.23 (s, 2H, CH2O), 2.52 (s, 6H, 2CH3-Mes), 1.98 (s, 3H,
CH3-Mes), 1.46 (s br, 12H, PMe), 1.42 (m br, 4H, PCH2), 1.34
(s br, 12H, PMe′), 1.25 (m br, 4H, PCH2′). 31P{1H} NMR

3630 Organometallics, Vol. 19, No. 18, 2000
Furno et al.
1
(toluene-d8, 298 K): δ 25.3 (s, J PW ) 288 Hz). 13C{1H} NMR
2.59 (s, 6H, 2CH3-Mes), 1.96 (s, 3H, CH3-Mes), 1.49 (s br, 12H,
PMe), 1.45 (m br, 4H, PCH2), 1.35 (s br, 12H, PMe′), 1.30 (m
br, 4H, PCH2′). 31P{1H} NMR (toluene-d8, 298 K): δ 24.2 (s,
1J PW ) 286 Hz). 13C{1H} NMR (toluene-d8, 298 K): δ 250.0 (q,
2J CP ) 10 Hz, CMes), 154.2 (s, ipso-Mes), 138.5 (s, ipso-
diphenylmethoxy), 136.5 (s, o-Mes), 132.2 (s, p-diphenyl-
methoxy), 131.5 (s, p-Mes), 130.4 (s, o-diphenylmethoxy), 127.1
(s, m-Mes), 126.9 (s, m-diphenylmethoxy), 86.7 (pseudo-q,
OCHPh2), 33.0 (q, PCH2), 23.4 (m, PMe), 22.4 (s, 2CH3-Mes),
21.1 (s, CH3-Mes), 18.3 (m, PMe′). MS (FAB, toluene): m/e 797
(M+), 665 (M+ - Mes), 647 (M+ - dmpe), 615 (M+ - diphen-
ylmethoxy), 497 (M+ - 2dmpe), 460 (M+ - dmpe - diphenyl-
methoxy), 307 (M+ - 2dmpe - diphenylmethoxy). Anal. Calcd
for WC35H54P4O (797.95): C, 52.63; H, 6.77. Found: C, 51.89;
H, 6.41%
(toluene-d8, 298 K): δ 263.1 (q, 2J CP ) 10 Hz, CMes), 150.5 (s,
ipso-Mes), 136.4 (s, ipso-Bn), 133.8 (s, p-Bn), 129.6 (s, o-Mes),
128.9 (s, o-Bn), 128.1 (s, m-Bn), 127.8 (s, p-Mes), 126.5 (s,
m-Mes), 74.0 (pseudo-q, W-O-C), 33.6 (q, PCH2), 23.0 (s,
2CH3-Mes), 22.6 (m, PMe), 21.2 (s, CH3-Mes), 18.4 (m, PMe′).
Anal. Calcd for WC29H50P4O (721.73): C, 48.21; H, 6.93. Found:
C, 48.02; H, 6.57.
P r ep a r a tion of tr a n s-W(CMes)(η1-OiP r )(d m p e)2 (11).
Compound 7 (30 mg, 0.0487 mmol) was dissolved in toluene
(5 mL) and acetone (5.66 mg, 0.0974 mmol) added at room
temperature. The solution was then allowed to warm to 60
°C. The compound 11 is spectroscopically observable by 31P
NMR after a few minutes, but the reaction was complete only
after 2 days at 60 °C. The solvent was then removed in vacuo
and the precipitate recrystallized in diethyl ether to afford 11
P r ep a r a tion of tr a n s-W(CMes)(η1-m eth oxyp yr id in e)-
(d m p e)2 (14). Compound 7 (30 mg, 0.0487 mmol) was dis-
solved in toluene (5 mL) and pyridine-2-carbaldehyde (4.63 µL,
0.0487 mmol) added by microsyringe at -40 °C. The compound
14 is spectroscopically observable by 31P NMR after a few
minutes at -40 °C. 14 decomposes within minutes at room
1
as orange crystals. Yield: 28 mg (93%). H NMR (toluene-d8,
298 K): δ 6.71 (s, 2H, Mes), 3.56 (sp, 1H, O-CHMe2), 2.64 (s,
2CH3-Mes), 2.07 (s, CH3-Mes), 1.52 (s br, 12H, PMe), 1.47 (m
br, 4H, PCH2), 1.41 (s br, 12H, PMe′), 1.34 (m br, 4H, PCH2′).
31P{1H} NMR (toluene-d8, 298 K): δ 23.4 (s, J PW ) 288 Hz).
1
13C{1H} NMR (toluene-d8, 298 K): δ 248.5 (q, J CP ) 9 Hz,
temperature and could not be isolated. H NMR (toluene-d8,
2
1
CMes), 151.2 (s, ipso-Mes), 136.5 (s, o-Mes), 130.2 (s, p-Mes),
128.4 (s, m-Mes), 78.7 (s br, O-CHMe2), 33.6 (q, PCH2), 23.0
(s, 2CH3-Mes), 22.5 (m, PMe), 21.2 (s, CH3-Mes), 18.9 (m,
PMe′). MS (FAB, toluene): m/e 674 (M+), 615 (M+ - OiPr), 524
(M+ - dmpe), 465 (M+ - dmpe - OiPr).
233 K): aromatic hydrogens of the pyridine ring: δ 8.2 (6-
CH, dd), 7.35 (5-CH, d), 6.55 (3-CH, dd), 6.40 (4-CH, ddd), 6.65
(s, 2H, Mes), 2.59 (s, 6H, 2CH3-Mes), 2.04 (s, 3H, CH3-Mes),
1.47 (s br, 12H, PMe), 1.43 (m br, 4H, PCH2), 1.39 (m br, 4H,
PCH2′), 1.35 (s br, 12H, PMe′), 1.30 (m br, 4H, PCH2′). 31P-
{1H} NMR (toluene-d8, 233 K): δ 25.5 (s, 1J PW ) 287 Hz). 13C-
P r ep a r a t ion of tr a n s-W(CMes)(η1-1-p h en ylet h oxy)-
(d m p e)2 (12). Compound 7 (30 mg, 0.0487 mmol) was dis-
solved in toluene (5 mL) and acetophenone (6.16 µL, 0.0487
mmol) added by microsyringe at room temperature. The
solution was then allowed to warm to 60 °C. The compound
12 is spectroscopically observable after a few minutes, but the
reaction was complete only after 2 days at 60 °C. The solvent
was then removed in vacuo and the precipitate recrystallized
in diethyl ether to afford 12 as orange crystals. Yield: 28 mg
(93%). 1H NMR (toluene-d8, 298 K): δ 7.64 (d, o-1-phen-
2
{1H} NMR (toluene-d8, 233 K): δ 249.5 (pseudo-q, J CP ) 9
Hz, CMes), 154.3 (s, ipso-Mes), 136.5 (s, o-Mes), 131.5 (s,
p-Mes), 127.1 (s, m-Mes), 75.5 (pseudo-q, -OCH-), 33.0 (q,
PCH2), 23.4 (m, PMe), 22.4 (s, 2CH3-Mes), 21.1 (s, CH3-Mes),
18.3 (m, PMe′).
P r ep a r a t ion of tr a n s-W(CMes)(η1-4-for m ylp h en oxy)-
(d m p e)2 (15). Compound 7 (30 mg, 0.0487 mmol) was dis-
solved in toluene (5 mL) and 4-hydroxybenzaldehyde (5.94 mg,
0.0487 mmol) added at room temperature. The reaction was
complete within minutes and the solvent removed in vacuo.
After recrystallization from toluene/pentane at -30 °C, 15 was
obtained as orange crystals. Yield: 28 mg (93%). 1H NMR
(toluene-d8, 298 K): δ 9.76 (s, 1H, aryl-C(O)H), 7.60 (s br, 2H,
aryl H’s), 6.62 (s, 2H, Mes), 5.98 (d, 2H, 8.7 Hz, aryl H’s), 2.48
(s, 6H, 2CH3-Mes), 2.01 (s, 3H, CH3-Mes), 1.48 (s br, 12H,
PMe), 1.36 (m br, 8H, PCH2), 1.24 (s br, 12H, PMe′). 31P{1H}
ylethoxy), 7.10 (t, p-1-phenylethoxy), 6.96 (m, m-1-phen-
3
ylethoxy), 6.61 (s, 2H, Mes), 4.17 (q, 1H, OCHMePh, J HH
)
6.3 Hz), 2.58 (s, 6H, 2CH3-Mes), 1.97 (s, 3H, CH3-Mes), 1.52
(m br, 4H, PCH2), 1.43 (s br, 12H, PMe), 1.39 (s br, 12H, PMe′),
1.29 (m br, 4H, PCH2′), 1.02 (d, 3H, OCHCH3Ph, 3J HH ) 6 Hz).
31P{1H} NMR (toluene-d8, 298 K): δ 23.6 (m, 18 Hz wide, 1J PW
) 292 Hz), 23.0 (m, 18 Hz wide, 1J PW ) 292 Hz). 13C{1H} NMR
2
1
(toluene-d8, 298 K): δ 248.2 (pseudo-q, J CP ) 10 Hz, CMes),
NMR (toluene-d8, 298 K): δ 29.4 (s, J PW ) 285 Hz). 13C{1H}
2
155.4 (s, ipso-Ph), 148.5 (s, ipso-Mes), 136.2 (s, o-Mes), 132.8
(s, p-Mes), 131.1 (s, p-Ph), 128.7 (s, m-Mes), 127.9 (s, o-Ph),
126.6 (s, m-Ph), 77.7 (s, W-OCMePh), 33.3 (q, PCH2), 31.5 (s,
W-OCCH3Ph), 22.8 (m, PMe), 22.7 (s, 2CH3-Mes), 21.1 (s, CH3-
Mes), 19.0 (m, PMe′). Anal. Calcd for WC30H52P4O (735.88):
C, 48.92; H, 7.07. Found: C, 49.15; H, 7.25.
NMR (toluene-d8, 298 K): δ 261.7 (pseudo-q, J CP ) 10 Hz,
CMes), 188.0 (s, aryl-C(O)H), 174.7 (s, W-O-C), 147.5 (s, ipso-
Mes), 135.8 (s, o-Mes), 132.2 (s, p-Mes), 129.2 (s, m-Mes), 124.0
(s, m-4-formylphenoxy), 120.0 (s, o-4-formylphenoxy), 33.4 (q,
PCH2), 22.9 (s, 2CH3-Mes), 22.6 (m, PMe), 21.2 (s, CH3-Mes),
18.9 (m, PMe′). Anal. Calcd for WC29H48P4O2 (735.85): C, 47.29;
H, 6.52. Found: C, 47.56; H, 6.48.
P r ep a r a tion of tr a n s-W(CMes)(η1-d ip h en ylm eth oxy)-
(d m p e)2 (13). Compound 7 (30 mg, 0.0487 mmol) was dis-
solved in toluene (5 mL) and benzophenone (18 mg, 0.0974
mmol) added at room temperature. The solution was then
allowed to warm to 60 °C. The compound 13 is spectroscopi-
cally observable by 31P NMR after a few minutes, but the
reaction was complete only after 36 h at 60 °C. The solvent
was then removed in vacuo and the precipitate recrystallized
in diethyl ether to afford 13 as orange crystals. Yield: 27 mg
(91%). 1H NMR (toluene-d8, 298 K): δ 7.60 (m, 4H, o-
diphenylmethoxy), 7.24 (m, 2H, p-diphenylmethoxy), 7.00 (m,
4H, m-diphenylmethoxy), 6.59 (s, 2H, Mes), 5.08 (s br, OCHPh2),
Ack n ow led gm en t. Financial support for this work
from the Swiss National Science Foundation is grate-
fully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of positional
and thermal parameters and complete lists of bond lengths
and angles. This material is available free of charge via the
Internet at http://pubs.acs.org.
OM000332C