Synthesis and reactivity of Ru(PPh3)3(CO)HF and the N-heterocyclic carbene derivatives Ru(NHC)(PPh3)2(CO)HF

Article abstract of DOI:10.1021/om070164p

The reaction of Ru(PPh₃)₃(CO)H₂ with excess Et₃N·3HF at elevated temperature affords the hydride fluoride complex Ru(PPh₃)₃(CO)HF (1). This reacts with a series of N-heterocyclic carbenes (NHCs) at ambient temperature to form the mono-NHC products Ru(NHC)(PPh₃)₂(CO)HF (NHC = IMe ₄ (2), IEt₂-Me₂ (3), ICy (4), I ⁱPr₂Me₂ (5)). Complexes 2-4 convert from the trans- to cis-phosphine isomers in solution over weeks (relative rates 2 > 3 ?4), while 5 undergoes both isomerization and disproportionation to yield cis-Ru(IⁱPr₂Me₂)(PPh₃) ₂(CO)HF (6), 1, and Ru(IⁱPr₂Me ₂)₂(PPh₃)(CO)HF (7) in a matter of hours. The molecular structures of compounds 1-4 have been determined by X-ray crystallography.

Full text of DOI:10.1021/om070164p

3484
Organometallics 2007, 26, 3484-3491
Synthesis and Reactivity of Ru(PPh3)3(CO)HF and the
N-Heterocyclic Carbene Derivatives Ru(NHC)(PPh3)2(CO)HF
Steven P. Reade,† Devendrababu Nama,‡ Mary F. Mahon,† Paul S. Pregosin,*,‡ and
Michael K. Whittlesey*,†
Department of Chemistry, UniVersity of Bath, ClaVerton Down, Bath BA2 7AY, U.K., and Laboratory of
Inorganic Chemistry, ETHZ, Honggerberg, CH-8093 Zurich, Switzerland
ReceiVed February 22, 2007
The reaction of Ru(PPh3)3(CO)H2 with excess Et3N‚3HF at elevated temperature affords the hydride
fluoride complex Ru(PPh3)3(CO)HF (1). This reacts with a series of N-heterocyclic carbenes (NHCs) at
ambient temperature to form the mono-NHC products Ru(NHC)(PPh3)2(CO)HF (NHC ) IMe4 (2), IEt2-
Me2 (3), ICy (4), IiPr2Me2 (5)). Complexes 2-4 convert from the trans- to cis-phosphine isomers in
solution over weeks (relative rates 2 > 3 . 4), while 5 undergoes both isomerization and disproportionation
to yield cis-Ru(IiPr2Me2)(PPh3)2(CO)HF (6), 1, and Ru(IiPr2Me2)2(PPh3)(CO)HF (7) in a matter of hours.
The molecular structures of compounds 1-4 have been determined by X-ray crystallography.
common. Consequently, a better understanding of the funda-
mental bonding interactions that can help to stabilize M-F
complexes has also developed,9,10 such that there are now a
range of synthetic and catalytic applications.4,7,11
In the majority of M-F complexes, one or more tertiary
phosphines are present as ancillary ligands, although not always
in an innocent capacity.12 For some time, we have been
interested in determining how stability and reactivity are affected
upon replacing PR3 by an N-heterocyclic carbene (NHC), given
that NHCs are significantly better σ-donor ligands.13 Having
recently established that NHC ruthenium hydride chloride
complexes show patterns of reactivity comparatively different
Introduction
Fluoride complexes of the platinum group metals constitute
a largely neglected class of compounds, which have long been
considered as being too unstable and/or too reactive to be of
any value. This is primarily because of the supposed incompat-
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electronegative fluoride ligand.1 However, the development over
the last 5-10 years of more widely applicable synthetic routes
allowing fluoride to be introduced into the coordination sphere
of a metal (e.g., AgF metathesis,2 C-F bond activation,3-5
development of mild HF sources such as Et3N‚3HF,2,6 and
oxidative addition of XeF27,8) has made M-F complexes more
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* To whom correspondence should be addressed. E-mail: chsmkw@
bath.ac.uk (M.K.W.).
† University of Bath.
‡ ETHZ.
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10.1021/om070164p CCC: $37.00 © 2007 American Chemical Society
Publication on Web 06/07/2007

Ru(PPh3)3(CO)HF and Carbene DeriVatiVes
Organometallics, Vol. 26, No. 14, 2007 3485
Scheme 1
from those of the related RuH2 compounds,14 we decided to
investigate the synthesis and properties of the hydride fluoride
analogues. We now report the preparation of the N-Me-, N-Et-,
N-Cy-, and N-iPr-substituted carbene complexes Ru(NHC)-
(PPh3)2(CO)HF, which are formed upon addition of the free
NHCs to the previously unknown tris(phosphine) hydride
fluoride complex Ru(PPh3)3(CO)HF. Hitherto, there have been
just four fully characterized late M-F complexes containing
NHC ligands reported: one by ourselves (Ru),15,16 one by
Sadighi (Au),17 and two by Radius and co-workers (Ni).18
Herein, we describe the first indication that the reactivity of
M-F species can be significantly altered by different N-
substituents on the carbene.
Figure 1. 1H-19F HOESY spectrum of complex 2 showing a
selective NOE contact to one NHC methyl group as well as the
ortho protons of the triphenylphosphine (benzene-d6, 400 MHz, 298
K).
low-frequency 19F position is consistent with a fluoride ligand
bound to a saturated ruthenium center.21 Although no coupling
between the hydride and fluoride resonances was observable,
their combined presence in the same molecule was confirmed
Results and Discussion
Formation, Structural Characterization, and Reactivity
of Ru(PPh3)3(CO)HF. When a THF solution of Ru(PPh3)3-
(CO)H2 was heated at 85 °C in the presence of 3 equiv of Et3N‚
3HF, a red solution was rapidly formed, which upon workup
allowed isolation of the hydride fluoride complex Ru(PPh3)3-
(CO)HF (1).19 This is formed as a white, air-sensitive crystalline
solid, which is only moderately soluble in toluene, benzene, or
THF. The proton NMR spectrum of 1 (benzene-d6) revealed
the presence of a single hydride resonance at δ -5.05, with
coupling to one trans (JHP ) 112.5 Hz) and two cis phosphorus
nuclei (JHP ) 25.2 Hz), which correlates with the geometry
shown in Scheme 1. The 31P{1H} NMR spectrum consists of
an A2X pattern, while the Ru-F signal appeared as a quartet at
δ -385.1 (JFP ) 23.5 Hz) in the 19F NMR spectrum.20 This
1
by H-19F HMBC correlation spectroscopy. The compound
displayed a single carbonyl IR absorption band at 1917 cm-1
,
lower than the values for the related hydride chloride species
Ru(PPh3)3(CO)HCl (1920 cm-1 22
and Ru(P-P)(PPh3)(CO)HCl
(dppm/dppp/dppb/dppf, 1920 cm-1; dppe, 1925 cm-1 23
or the
)
)
hydride bromide derivative Ru(PPh3)3(CO)HBr (1950 cm-1).24
Complex 1 proved to be inert upon exposure to either H2 or
ethene but reacted with CO in benzene at room temperature to
afford a white precipitate of Ru(PPh3)2(CO)2HF.25 The relatively
high frequency hydride resonance (δ -2.58) is in agreement
with the presence of a trans carbonyl ligand. The 19F NMR
spectrum showed a broad singlet for the Ru-F signal, although
shifted >30 ppm to lower frequency than that for 1.
Synthesis and Characterization of Ru(NHC)(PPh3)2(CO)-
HF (NHC ) IMe4, IEt2Me2, ICy, IiPr2Me2). Addition of ca.
1.5 equiv of the NHC ligands IMe4, IEt2Me2, ICy, and IiPr2-
Me2 to toluene suspensions of 1 led to the formation of colorless,
solid-free solutions of the mono-NHC complexes Ru(NHC)-
(PPh3)2(CO)HF (NHC ) IMe4 (2), IEt2Me2 (3), ICy (4), IiPr2-
Me2 (5)) within the space of approximately 5 min. In all cases,
except for 4, the complexes precipitated as white solids within
a period of 10-15 min.26 Crystals of 2-4 were isolated from
benzene/hexane solutions and proved suitable for a single-crystal
(13) (a) Scott, N. M.; Nolan, S. P. Eur. J. Inorg. Chem. 2005, 1815. (b)
N-Heterocyclic Carbenes in Synthesis; Nolan, S. P., Ed.; Wiley-VCH:
Weinheim, Germany, 2006. (c) Glorius, F. A. Top. Organomet. Chem. 2007,
21, 1.
(14) Burling, S.; Kociok-Ko¨hn, G.; Mahon, M. F.; Whittlesey, M. K.;
Williams, J. M. J. Organometallics 2005, 24, 5868. See also ref 26.
(15) Chatwin, S. L.; Davidson, M. G.; Doherty, C.; Donald, S. M.; Jazzar,
R. F. R.; Macgregor, S. A.; McIntyre, G. J.; Mahon, M. F.; Whittlesey, M.
K. Organometallics 2006, 25, 99.
(16) An interaction between ruthenium and an o-fluorine substituent in
the fluorinated NHC 1,3-bis(2,6-difluorophenyl)imidazol-2-ylidene has
recently been reported: Ritter, T.; Day, M. W.; Grubbs, R. H. J. Am. Chem.
Soc. 2006, 128, 11768.
(17) Laitar, D. S.; Mu¨ller, T. G.; Gray, T. G.; Sadighi, J. P. Organo-
metallics 2005, 24, 4503.
(21) Huang, D. J.; Koren, P. R.; Folting, K.; Davidson, E. R.; Caulton,
K. G. J. Am. Chem. Soc. 2000, 122, 8916.
(22) Levison, J. J.; Robinson, S. D. J. Chem. Soc. A 1970, 2947.
(23) Santos, A.; Lo´pez, J.; Montoya, J.; Noheda, P.; Romero, A.;
Echavarren, A. M. Organometallics 1994, 13, 3605.
(18) (a) Schaub, T.; Radius, U. Chem. Eur. J. 2005, 11, 5024. (b) Schaub,
T.; Backes, M.; Radius, U. J. Am. Chem. Soc. 2006, 128, 15964.
(19) The reaction of the dihydride complex with anhydrous HF yields
the cationic fluoride-bridged dimer [{Ru(PPh3)2(CO)}2(µ-F)3]+.8e
(20) The 19F NMR resonances of 1-5 in benzene-d6 varied in appearance,
ranging from broad, unresolved singlets to well-resolved quartets. We thank
an anonymous reviewer, who suggested that the broadening may arise from
hydrogen bonding to adventitious water or HF and that addition of dry
CsF can scavenge such impurities. Indeed, we find that, upon addition of
CsF to samples of 2 and 3, broad 19F resonances are sharpened to quartets,
allowing JFP coupling constants of 23.0 Hz to be determined in both cases.
(24) Sa´nchez-Delgado, R. A.; Thewalt, U.; Valencia, N.; Andriollo, A.;
Ma´rquez-Silva, R.-L.; Puga, J.; Scho¨llhorn, H.; Klein, H.-P.; Fontal, B.
Inorg. Chem. 1986, 25, 1097.
(25) The analogous complex Ru(PtBu2Me)2(CO)2HF has been reported
by Caulton and co-workers and found to have a high-frequency hydride
chemical shift: Poulton, J. T.; Sigalas, M. P.; Folting, K.; Streib, W. E.;
Eisenstein, O.; Caulton, K. G. Organometallics 1994, 13, 1476.

3486 Organometallics, Vol. 26, No. 14, 2007
Reade et al.
1
1
Figure 2. Section of the H (lower trace) and H{19F} (upper trace) NMR spectra of complex 2 (d8-THF, 200 MHz, 298 K).
Figure 4. Molecular structure of 2. Thermal ellipsoids are
represented at the 30% probability level. Carbon-bound hydrogen
atoms and disordered solvent have been omitted for clarity. Selected
Figure 3. Molecular structure of 1. Thermal ellipsoids are
distances (Å) and angles (deg): Ru(1)-P(2) ) 2.3434(4), Ru(1)-
represented at the 30% probability level. Carbon-bound hydrogen
atoms and solvent have been omitted for clarity. Selected distances
(Å) and angles (deg): Ru(1)-P(1) ) 2.3608(5), Ru(1)-P(2) )
2.4422(5), Ru(1)-P(3) ) 2.3462(5), Ru(1)-C(1) ) 1.819(3), Ru-
(1)-F(1) ) 2.0986(15); P(1)-Ru(1)-P(3) ) 150.13(2), F(1)-Ru-
(1)-C(1) ) 177.94(11).
P(2) ) 2.3499(4), Ru(1)-C(1) ) 1.8144(16), Ru(1)-C(2) )
2.1702(16), Ru(1)-F(1) ) 2.0887(9); P(1)-Ru(1)-P(2) ) 164.189-
(15), F(1)-Ru(1)-C(1) ) 175.62(6).
proximate methyl group, which was confirmed via selective 1H-
{19F} decoupling (Figure 2). No exchange peaks were observed
in the phase-sensitive proton 2-D NOESY map, indicative of a
significant barrier to Ru-CNHC rotation. The 31P{1H} spectrum
of 2 shows a singlet at δ 44.8, while the 19F resonance is
observed as a broad multiplet at δ -353.3.20
X-ray study. Isolation of X-ray-quality crystals of 5 was
precluded by its solution reactivity, which is discussed further
below.
Proton NMR spectroscopy revealed hydride resonances
between δ -5 and -6 for 2-5 in benzene-d6, each with a
doublet of triplets multiplicity resulting from coupling to both
19F and 31P. The high-frequency hydride position combined with
the JHP values (see Experimental Section) implies incorporation
of the NHC ligand trans to hydride (Scheme 1).
Restricted rotation about the M-CNHC bond was established
in all cases by 1H NMR spectroscopy. Thus, complex 2 shows
four nonequivalent carbene methyl resonances. The N-CNHC-N
plane is not parallel to the P-Ru-P axis, and consequently,
one of the two N-methyl resonances is closer to the Ru-F group.
As a consequence, the 2-D 19F-1H HOESY spectrum affords
a selective NOE contact from the fluoride ligand to this methyl
group (Figure 1). As each N-Me resonance shows a selective
NOESY cross-peak to its proximate C-Me partner, all four of
the methyl signals can be fully assigned. Interestingly, there is
a selective, through-space interaction from the 19F spin to the
X-ray Crystal Structures of 1-4. The solid-state structures
of 1-4 were determined by X-ray crystallography and are
shown in Figures 3-6. A distorted-octahedral geometry at the
ruthenium center is observed in all cases with the two trans
phosphines tilted toward the hydride (P-Ru-P: 1, 150.13-
(2)°: 2, 164.19(2)°; 3, 168.21(4)°: 4, 161.94(3)°), a feature also
common to the structure of Ru(PPh3)3(CO)H2.27 As expected,
the structures contain fluoride ligands trans to the CO groups,
enhancing push-pull stabilization.9 Unfortunately, carbonyl/
fluoride disorder precludes determination of accurate Ru-F
distances in 3 and 4. However, in the absence of such disorder
it is noteworthy that the Ru-F bond distance in 2 (2.0887(9)
Å) is somewhat shorter than the comparable distance in 1
(2.0986(15) Å), although they both lie in the range reported
for the related complexes Ru(PPh3)2(CO)2F2 (2.011(4) Å),8c Ru-
(dmpe)2F(FHF) (2.101(3) Å),5 Ru(PtBu2Me)2(CO)(dCF2)HF
(2.065(1) Å),21 and Ru(IMes)2(CO)HF (2.019(5) Å).15 The
orientation of the phosphine ligands relative to the carbene is
similar in structures 2-4, such that the NHC ring is sandwiched
by one phenyl ring from each triphenylphosphine, as shown in
(26) This behavior contrasts markedly with that of the hydride chloride
analogue Ru(PPh3)3(CO)HCl, which we have recently shown reacts with
IiPr2Me2 in a very different way: Burling, S.; Mahon, M. F.; Powell, R.
E.; Whittlesey, M. K.; Williams, J. M. J. J. Am. Chem. Soc. 2006, 128,
13702.
(27) Junk, P. C.; Steed, J. W. J. Organomet. Chem. 1999, 587, 191.

Ru(PPh3)3(CO)HF and Carbene DeriVatiVes
Organometallics, Vol. 26, No. 14, 2007 3487
Figure 7. Space-filling plot of 2, viewed along the C3-Ru1-C4
bisector, to illustrate the solid-state structural sandwiching of the
NHC moiety by one phenyl group from each triphenylphosphine
ligand. Relevant carbon atoms are highlighted in black.
Scheme 2
Figure 5. Molecular structure of 3. Thermal ellipsoids are
represented at the 30% probability level. Carbon-bound hydrogen
atoms and disordered components have been omitted for clarity.
Atoms labeled with a prime are related to those in the asymmetric
1
unit by the symmetry operation -x, y, /2 - z. Selected distances
(Å) and angles (deg): Ru(1)-P(1) ) 2.3540(7), Ru(1)-P(1)′ )
2.3540(7), Ru(1)-C(1) ) 1.944(5), Ru(1)-C(2) ) 2.196(4), Ru-
(1)-F(1) ) 1.976(5); P(1)-Ru(1)-P(1)′ ) 168.21(4), F(1)-Ru-
(1)-C(1) ) 174.7(8).
2).28 Thus, in the case of 2, depletion of the triplet Ru-H
resonance was accompanied by the formation of a doublet of
doublet of doublets hydride signal at δ -6.40, with characteristic
trans and cis values of JHP (128.8, 27.1 Hz). Heteronuclear
correlation experiments facilitated the assignment of two
phosphorus resonances at δ 42.0 and 23.1 and a broad 19F signal
(-343.1 ppm) to the cis-phosphine product. Qualitatively, the
rate of isomerization decreased in the order 2 > 3 . 4.
We have indirect evidence that the isomerization process is
initiated by loss of PPh3. Thus, 2 reacted with IMe4 and CO at
room temperature to give the bis(carbene) and dicarbonyl
complexes Ru(IMe4)2(PPh3)(CO)HF (1H, δ -5.58, dd, JHP
)
27.4 Hz, JHF ) 6.0) and Ru(IMe4)(PPh3)(CO)2HF (1H, δ -2.65,
dd,JHP )23.5,JHF )8.2Hz),respectively(Ru(IMe4)(PPh3)(CO)2-
HF reacted further with CO to give Ru(IMe4)(PPh3)(CO)3 as
the ultimate reaction product). Phosphine loss was also found
upon dissolution of 3 in pyridine, which gave the mono-
(phosphine) complex Ru(IEt2Me2)(PPh3)(CO)(py)HF (1H, δ
-11.47, br d, JHP ) 22.6 Hz; 31P{1H}, δ 46.8, d, JPF ) 23.6
Hz; 19F, δ -289.1, d, JPF ) 23.0 Hz). Efforts to observe direct
phosphine exchange proved unsuccessful, as there was no
incorporation of P(p-tolyl)3 found when the isomerization of 2
was run in THF-d8 with 10 equiv of free phosphine added.
Reactivity of 5. The N-iPr complex 5 proved to be more
unstable in solution than complexes 2-4, degrading over a
period of only hours via both isomerization and disproportion-
ation. At early times, 5 displayed signals similar to those seen
for 2: the hydride appeared (benzene-d6) as a doublet of triplets
Figure 6. Molecular structure of 4. Thermal ellipsoids are
represented at the 30% probability level. Carbon-bound hydrogen
atoms and the minor disordered component have been omitted for
clarity. Selected distances (Å) and angles (deg): Ru(1)-P(2) )
2.3534(8), Ru(1)-P(3) ) 2.3497(8), Ru(1)-C(1) ) 1.851(5), Ru-
(1)-C(2) ) 2.192(3), Ru(1)-F(1) ) 2.021(2); P(2)-Ru(1)-P(3)
) 161.94(3), F(1)-Ru(1)-C(1) ) 176.9(4).
Figure 7 for Ru(IMe4)(PPh3)2(CO)HF (2). Closest distances from
the mean NHC ring plane to carbon atoms in the each flanking
arene are 3.01 and 3.04 Å in 2, 3.11 and 3.11 Å in 3, and 3.17
and 3.21 Å in 4. These data broadly reflect the steric trend of
the carbene substituents in each case, while also suggesting the
presence of π-π interactions in all three compounds.
Reactivity of 2-4. Slow, but clean, isomerization of 2-4 to
their corresponding cis-phosphine isomers was seen in THF-d8
at ambient temperature over a period of 1-2 weeks (Scheme
(28) While 2 and 3 (4 was not investigated) isomerized in benzene as
well as THF, the reactions were not as clean and were always accompanied
by variable amounts (5-20% by 1H NMR) of species showing a triplet
hydride resonance at ca. δ -15. There were no corresponding Ru-F
resonances in the 19F NMR spectra, prompting us to suggest that these
species are hydrolysis products resulting from reaction of Ru-F with traces
of water on glassware or cannula or in the solvent.

3488 Organometallics, Vol. 26, No. 14, 2007
Reade et al.
isomer of 5, and the bis-NHC complex 7 (Scheme 3). After
several hours, the relative intensities of the four Ru species are
ca. 1:1:3:4 for 5, 6, 1, and 7, respectively: i.e., 5 and 6 have
become the minor components. Phase sensitive 2-D NOESY
spectroscopy reveals that none of these complexes are in
equilibrium on the NMR time scale (Figure 10). The cis-
phosphine hydride fluoride 6 gives broad NMR resonances at
298 K, although cooling below 283 K (Figure 11) gives the
expected coupling of the hydride signal to two inequivalent
phosphine ligands (splitting by Ru-F is hard to resolve).
The major components, complexes 1 and 7, arise from a
disproportionation reaction. The bis-IiPr2Me2 complex, 7,
revealed a sharp doublet of doublets for its hydride resonance
at δ -7.57, with the two bond interactions, 28.3 and 7.5 Hz,
assigned to JHP and JHF, respectively. Complex 7 displayed a
sharp doublet at 44.6 ppm in the 31P{1H} NMR spectrum (JPF
) 41.4 Hz) and a broad 19F signal at ca. δ -344. A 13C{1H}-
1H HMBC correlation from the hydride resonance (Figure 12)
shows three high-frequency 13C signals at ca. δ 184, 192
(carbenic carbons), and 204 (CO) consistent with the two NHC
ligands in 7 being inequivalent.
Figure 8. 1H-19F HOESY spectrum of complex 5 showing a
selective NOE contact to one of the two isopropyl methine protons
and the ortho protons of the triphenylphosphine (benzene-d6, 400
MHz, 298 K).
Summary
The new hydride fluoride complex Ru(PPh3)3(CO)HF, which
can be prepared by reaction of Ru(PPh3)3(CO)H2 with Et3N‚
3HF, reacts readily with the N-heterocyclic carbenes IMe4, IEt2-
Me2, ICy, and IiPr2Me2 to afford the new fluoro NHC complexes
Ru(NHC)(PPh3)2(CO)HF in yields of ca. 60%. The subsequent
stability of these species proves to be highly dependent on the
N substituents, with the isopropyl derivative undergoing rapid
isomerization and disproportionation in solution in a matter of
hours. Such a process may have implications in catalytic
reactions involving, for example, large phosphine or phosphite
ligands and NHCs.
(δ -5.94, JPH ) 25.6, JHF ) 4.8 Hz), the 31P{1H} spectrum
showed equivalent P atoms at δ 40.5 (JPF ) 27.6 Hz), and the
Ru-F resonance was observed at δ -355.6 as a poorly resolved
multiplet. The two N-iPr (and C-Me) groups are nonequivalent,
and again, the 2-D 19F-1H HOESY spectrum showed a selective
contact to one of the two iPr methine protons at δ 6.29 (Figure
8), thereby facilitating the assignment of all of the aliphatic
protons.
1H NMR spectroscopy (THF-d8) as a function of time
revealed facile depletion of the triplet hydride signal for 5 and
the formation of three new groups of resonances (Figure 9) that
can be assigned to 1, complex 6, which is the cis-phosphine
With respect to the more general properties of late-metal
fluoride complexes, we note that there is no evidence for the
Figure 9. 1H NMR spectrum of complex 5 after several hours showing the four Ru-species 5, 6, 1, and 7 in the ratio ca. 1/1/3/4 (THF-d8,
700 MHz, 298 K).
Scheme 3

Ru(PPh3)3(CO)HF and Carbene DeriVatiVes
Organometallics, Vol. 26, No. 14, 2007 3489
Figure 10. Section of the hydride region of the phase-sensitive NOESY spectrum after isomerization and disproportionation of 5, which
reveals the lack of exchange between 1, 6, and 7 (benzene-d6, 400 NMR, 298 K).
Figure 11. Variable-temperature NMR spectra of complex 6, showing the eight line pattern below 283 K (THF-d8, 400 MHz).
atmosphere of argon. Solvents were purified using an MBraun SPS
solvent system (toluene, Et2O) or Innovative Technologies solvent
system (THF) or were purified under a nitrogen atmosphere from
sodium benzophenone ketyl (benzene, hexane) or Mg/I2 (ethanol).
NMR solvents (Aldrich) were vacuum-transferred from potassium
formation of “H-F” type complexes, such as described by
Grushin,6b,29 Perutz,4a,6a,30 and others.5,31 This is likely to be due
to the “hard” ruthenium atom in the [Ru(L)(PPh3)2(CO)]2+
fragment (L ) NHC, PPh3) which favors F- over “H-F” or
F-H-F-.10b In Ru(PPh3)3(CO)HF and Ru(NHC)(PPh3)2(CO)-
HF, the fluoride ligand remains firmly bound to the ruthenium,
despite the presence of a cis-hydride atom.
(benzene-d6, THF-d8). Ru(PPh3)3(CO)H2,32 IMe4, IEt2Me2, ICy, and
33,34
IiPr2Me2
were prepared via literature methods. Et3N‚3HF
(Aldrich) was used as received.
NMR spectra were recorded on Bruker Avance 400 and 500 MHz
(Bath) and DPX 200, 400, 500, and 700 MHz NMR spectrometers
Experimental Section
General Comments. All manipulations were carried out under
argon using standard Schlenk or glovebox techniques under an
(31) (a) Coulson, D. R. J. Am. Chem. Soc. 1976, 98, 3111. (b) Murphy,
V. J.; Hascall, T.; Chen, J. Y.; Parkin, G. J. Am. Chem. Soc. 1996, 118,
7428. (c) Murphy, V. J.; Rabinovich, D.; Hascall, T.; Klooster, W. T.;
Koetzle, T. F.; Parkin, G. J. Am. Chem. Soc. 1998, 120, 4372. (d) Gil-
Rubio, J.; Weberndo¨rfer, B.; Werner, H. J. Chem. Soc., Dalton Trans. 1999,
1437. (e) Vicente, J.; Gil-Rubio, J.; Bautista, D.; Sironi, A.; Masciocchi,
N. Inorg. Chem. 2004, 43, 5665.
(29) (a) Pilon, M. C.; Grushin, V. V. Organometallics 1998, 17, 1774.
(b) Roe, D. C.; Marshall, W. J.; Davidson, F.; Soper, P. D.; Grushin, V. V.
Organometallics 2000, 19, 4575.
(30) (a) Jasim, N. A.; Perutz, R. N. J. Am. Chem. Soc. 2000, 122, 8685.
(b) Jasim, N. A.; Perutz, R. N.; Foxon, S. P.; Walton, P. H. Dalton Trans.
2001, 1676.
(32) Ahmad, N.; Levison, J. J.; Robinson, S. D.; Uttley, M. F. Inorg.
Synth. 1974, 15, 48.

3490 Organometallics, Vol. 26, No. 14, 2007
Reade et al.
9.4 (s, CH3), 8.9 (s, CH3). 19F NMR: δ -353.3 (br s). IR (cm-1):
1888 (νCO). ESI-TOF MS: [M - HF + H]+ m/z 779.1894
(theoretical m/z 779.1900).
Ru(IEt2Me2)(PPh3)2(CO)HF (3). Ru(PPh3)3(CO)HF (0.166 g,
0.18 mmol) and IEt2Me2 (0.041 g, 0.27 mmol) were dissolved in
toluene (8 mL) and stirred at ambient temperature for 1 h, by which
time a white precipitate of Ru(IEt2Me2)(PPh3)2(CO)HF had formed.
Yield: 0.090 g (61%). Anal. Found (calcd) for C46H47N2OP2FRu:
C, 66.68 (66.89); H, 5.87 (5.74); N, 3.48 (3.39). 1H NMR (benzene-
d6, 400 MHz, 298 K): δ 8.07-8.00 (m, 12H, PC6H5), 7.10-6.98
(m, 18H, PC6H5), 3.73 (q, JHH ) 7.1 Hz, 2H, NCH2), 3.68 (br m,
2H, NCH2), 1.58 (s, 3H, NCH2CH3), 1.43 (s, 3H, NCH2CH3), 0.94
(t, JHH ) 7.1 Hz, 3H, CH3) 0.78 (t, JHH ) 7.1 Hz, 3H, CH3), -6.07
(dt, JHP ) 22.5 Hz, JHF ) 4.4 Hz, 1H, Ru-H). 31P{1H} NMR: δ
42.8 (d, JPF ) 25.8 Hz). 19F NMR: δ -363.0 (br s). IR (cm-1):
1891 (νCO). ESI-TOF MS: [M - HF + H]+ m/z 807.2201
(theoretical m/z 807.2214).
1
Figure 12. Section of the H-13C{1H} HMBC spectrum of 7 at
Ru(ICy)(PPh3)2(CO)HF (4). Ru(PPh3)3(CO)HF (0.20 g, 0.21
mmol) and ICy (0.060 g, 0.26 mmol) were dissolved in toluene
(10 mL), and the reaction mixture was stirred at room temperature
for 1 h. Reduction of the volume and addition of hexane afforded
white crystals of Ru(ICy)(PPh3)2(CO)HF. Yield: 0.12 g (60%).
Anal. Found (calcd) for C52H55N2OP2FRu: C, 68.41 (68.93); H,
ambient temperature, showing correlations to each of the two
nonequivalent carbene carbons and the carbonyl carbon (THF-d8,
700 MHz).
(ETHZ), at 298 K unless otherwise stated, and referenced to benzene
(1H, δ 7.15; 13C, δ 128.0) or THF (δ 3.58). 31P{1H} NMR chemical
shifts were referenced externally to 85% H3PO4 (δ 0.0). 2D
1
6.24 (6.12); N, 2.96 (3.09). H NMR (benzene-d6, 400 MHz, 298
K): δ 7.94 (m, 12H, PC6H5), 7.16-7.02 (m, 18H, PC6H5), 6.65
(d, JHH ) 2.2 Hz, 1H, NCH), 6.57 (d, JHH ) 2.2 Hz, 1H, NCH),
5.10 (br m, 1H, CH-Cy), 4.83 (m, 1H, CH-Cy), 1.73 (m, 2H, CH2-
Cy) 1.44-0.80 (m, CH2-Cy), -5.46 (dt, JHP ) 25.2 Hz, JHF ) 4.4
Hz, Ru-H, 1H). 31P{1H} NMR: δ 40.5 (d, JPF ) 27.5 Hz). 19F
NMR: δ -366.6 (t, JFP ) 27.5 Hz). IR (cm-1): 1912 (νCO). ESI-
TOF MS: [M - HF + H]+ m/z 887.2862 (theoretical m/z
887.2842).
experiments (1H COSY, H-X (X ) 13C, 31P) HMQC/HMBC,
1
NOESY) were performed using standard Bruker pulse sequences.
19F-1H HOESY experiments were acquired using the standard four-
pulse sequence and carried out using a doubly tuned TXI probe.
IR spectra were recorded as Nujol mulls on a Nicolet Nexus FTIR
spectrometer.
Ru(PPh3)3(CO)HF (1). A solution of Ru(PPh3)3(CO)H2 (1.3 g,
1.4 mmol) and Et3N‚3HF (0.69 g, 4.3 mmol) in THF (40 mL) was
heated at 85 °C for 5.5 h, cooled to room temperature, and
concentrated under vacuum, and Et2O (30 mL) was added to
precipitate a pink/cream solid. This was washed with Et2O (3 ×
20 mL) and dried in vacuo overnight to yield Ru(PPh3)3(CO)HF
as a white solid. Yield: 0.7 g (53%). Crystals suitable for X-ray
crystallography were obtained upon layering a THF solution with
hexane. Despite repeated attempts, we were unable to achieve
acceptable microanalysis results for 1, with the % C value always
low. 1H NMR (benzene-d6, 400 MHz, 298 K): δ 7.5-7.2 (m, 17H,
PC6H5), 6.9-6.6 (m, 28H, PC6H5), -5.05 (dt, JHP ) 112.5 Hz,
JHP ) 25.2 Hz, 1H, Ru-H). 31P{1H} NMR: δ 39.5 (m), 18.7 (m).
13C{1H} NMR: δ 206.3 (dt, JCF ) 65.0 Hz, JCP ) 13.6 Hz, Ru-
CO), 137.5 (d, JCP ) 26.0 Hz, PC6H5), 136.9 (virtual triplet (‘vt’),
JCP ) 20.9 Hz, PC6H5), 135.1 (m, PC6H5), 129.5 (s, PC6H5), 129.1
(s, PC6H5), 128.5 (s, PC6H5). 19F NMR: δ -385.1 (q, JFP ) 23.5
Hz). IR (cm-1): 1917 (νCO). ESI-TOF MS: [M - HF - PPh3 +
H]+ m/z 655.0891 (theoretical m/z 655.0898).
Ru(IiPr2Me2)(PPh3)2(CO)HF (5). Ru(PPh3)3(CO)HF (0.2 g, 0.21
mmol) and IiPr2Me2 (0.057 g, 0.32 mmol) were dissolved in toluene
(7 mL), and the mixture was stirred at ambient temperature for 1
h. The solution was filtered by cannula and the resulting white solid
washed with hexane (3 × 7 mL) and toluene (5 mL), yielding Ru-
(IiPr2Me2)(PPh3)2(CO)HF as a white solid. Yield: 0.11 g (60%).
The facile disproportionation/isomerization reaction of 5 prevented
1
microanalysis from being determined. H NMR (benzene-d6, 400
MHz, 298 K): δ 8.05-7.93 (m, 12H, PC6H5), 7.10-6.89 (m, 18H,
PC6H5), 6.29 (br sept, JHH ) 7.1, 1H, NCH), 5.71 (sept, JHH
)
7.1, 1H, NCH), 1.84 (s, 3H, CH3), 1.80 (s, 3H, CH3), 1.02 (d, JHH
) 7.1, 6H, NCH(CH3)2), 0.75 (d, JHH ) 7.1, 6H, NCH(CH3)2),
-5.94 (dt, JHP ) 25.6 Hz, JHF ) 4.8 Hz, Ru-H, 1H). 31P{1H}
NMR: δ 40.5 (d, JPF ) 27.6 Hz). 19F NMR: δ -355.6 (br m). IR
(cm-1): 1900 (νCO). ESI-TOF MS: [M - HF + H]+ m/z 835.2537
(theoretical m/z 835.2528).
Mass Spectrometry. A micrOTOF electrospray time-of-flight
(ESI-TOF) mass spectrometer (Bruker Daltonik GmbH) was used;
this was coupled to an Agilent 1200 LC system (Agilent Technolo-
gies). Rather than any chromatographic separation taking place,
the LC system was used as an autosampler and sample introduction
mechanism only. A 10 µL sample was injected into a 30/70 flow
of water/acetonitrile at 0.3 mL/min in the mass spectrometer. The
nebulizing gas used was N2, applied at a pressure of 1 bar. The
drying gas was also N2, supplied at a flow rate of 8 L/min and a
temperature of 200 °C. Positive ion mode was used with a
corresponding capillary voltage of -4000 V. Only full scan data
were acquired. Samples were prepared under inert-atmosphere
conditions in an MBraun glovebox by dissolving 1 mg of compound
in 1 mL of CH3CN, and then diluting 1 µL of the mixture to 1 mL.
For each acquisition 10 uL of 5 mM sodium formate was injected
after the sample as a calibrant over the mass range m/z 50-1500,
using the high precision calibration (HPC) algorithm. Data acquisi-
tion and automated processing were controlled via Compass
OpenAccess 1.2 software (Bruker Daltonik GmbH). The data for
Ru(IMe4)(PPh3)2(CO)HF (2). Ru(PPh3)3(CO)HF (0.20 g, 0.21
mmol) and IMe4 (0.038 g, 0.31 mmol) were dissolved in toluene
(10 mL) and the solution stirred at room temperature for 1 h. The
suspension was filtered by cannula, and the remaining white solid
was washed with hexane (3 × 7 mL) and toluene (5 mL) to afford
Ru(IMe4)(PPh3)2(CO)HF as a white solid. Yield: 0.10 g (60%).
Anal. Found (calcd) for C44H43N2OP2FRu: C, 66.26 (66.24); H,
1
5.80 (5.43); N, 3.16 (3.51). H NMR (benzene-d6, 400 MHz, 298
K): δ 8.05 (m, 12H, PC6H5), 7.05-6.99 (m, 18H, PC6H5), 3.04
(br s, 3H, NCH3), 3.24 (br s, 3H, NCH3), 1.37 (s, 3H, CH3), 1.27
(s, 3H, CH3), -5.19 (dt, JHP ) 22.5 Hz, JHF ) 4.4 Hz, 1H, Ru-
H). 31P{1H} NMR: δ 44.8. 13C{1H} NMR: δ 208.3 (dt, JCF
)
64.0 Hz, JCP ) 13.7 Hz, Ru-CO), 188.9 (Ru-C, br t), 136.9 (‘vt’,
JCP ) 20.4 Hz, PC6H5), 127.0-135.0 (PC6H5), 125.8 (s, CCH3d
CCH3), 125.1 (s, CCH3dCCH3), 35.8 (s, NCH3), 30.3 (s, NCH3),
(33) Ku¨hn, N.; Kratz, T. Synthesis 1993, 561.
(34) Nolan, S. P. Personal communication.

Ru(PPh3)3(CO)HF and Carbene DeriVatiVes
Organometallics, Vol. 26, No. 14, 2007 3491
Table 1. Crystal Data and Structure Refinement Details for Compounds 1-4
1
2
3
4
empirical formula
formula wt
C59H54FO2P3Ru
1008.00
C47H46FN2OP2Ru
836.87
C46H47FN2OP2Ru
825.87
C52H55FN2OP2Ru
905.99
T/K
150(2)
150(2)
150(2)
150(2)
wavelength
0.710 73
0.710 73
0.710 73
0.710 73
cryst syst
space group
monoclinic
Pn
monoclinic
C2/c
monoclinic
C2/c
monoclinic
P21/n
a/Å
b/Å
c/Å
12.9570(2)
12.4210(2)
15.1290(2)
90
96.749(1)
90
2417.97(6)
2
1.384
14.6000(1)
22.8140(2)
24.3010(2)
90
96.007(1)
90
8049.84(11)
8
1.381
23.5920(5)
9.9650(2)
18.0880(5)
90
112.962(1)
90
3915.44(16)
4
1.401
9.1570(1)
23.8970(4)
20.5620(3)
90
92.436(1)
90
4495.41(11)
4
1.339
R/deg
â/deg
γ/deg
U/Å3
Z
Dc/g cm-3
µ/mm-1
0.471
1044
0.512
3464
0.525
1712
0.464
1888
F(000)
cryst size/mm
min, max θ for data collecn/deg
index ranges
0.30 × 0.25 × 0.20
3.95, 27.49
-16 e h e 16;
-16 e k e 16;
-19 e l e 19
50 166
10 639, 0.0341
9833
multiscan
0.91, 0.88
10 639/3/600
1.035
0.38 × 0.30 × 0.05
3.53, 34.95
-23 e h e 23;
-36 e k e 36;
-39 e l e 39
94 781
17 581, 0.0513
13824
multiscan
0.97, 0.94
17 581/13/490
1.062
0.20 × 0.10 × 0.10
3.57, 27.47
-30 e h e 30;
-12 e k e 12;
-23 e l e 23
23 475
4448, 0.0499
3874
multiscan
0.90, 0.86
4448/3/260
1.253
0.15 × 0.10 × 0.05
3.79, 25.03
-10 e h e 10;
-25 e k e 28;
-24 e l e 24
35 757
7755, 0.0753
6130
multiscan
0.96, 0.91
7755/9/549
1.022
no. of rflns collected
no. of indep rflns, Rint
no. of obsd rflns (>2σ)
abs cor
max, min transmission
no. of data/restraints/params
goodness of fit on F2
final R1, wR2 (I > 2σ(I))
final R1, wR2 (all data)
largest diff peak, hole/e Å-3
abs structure param
0.0254, 0.0581
0.0303, 0.0604
0.678, -0.505
-0.054(14)
0.0391, 0.0783
0.0604, 0.0855
1.014, -0.700
0.0428, 0.0917
0.0544, 0.0949
0.364, -0.594
0.0404, 0.0792
0.0600, 0.0869
0.621, -0.990
compounds 2-5 show a consistent loss of HF from the expected
formula, with compound 1 also undergoing loss of PPh3. The
observed mass and isotope pattern perfectly matched the corre-
sponding theoretical values, as calculated from the expected
elemental formula with a loss of HF. These calculations were carried
out using the data processing software DataAnalysis 3.4 (Bruker
Daltonik GmbH).
The carbonyl and fluoride ligands also exhibited 1/1 disorder in
this structure, which was modeled in the refinement. Similarly, 78/
22 disorder between the fluoride and carbonyl ligands was
successfully modeled in 4, subject to the Ru-F, Ru-CCO, and CtO
distances being restrained to be similar in both partial fragments.
The hydrides in all four structures were located and refined at a
distance of 1.6 Å from the central ruthenium atoms.
Crystallographic data for 1-4 have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publica-
tions CCDC 632303 (1), 644339 (2), 644338 (3), and 634671 (4).
Copies of these data can be obtained free of charge on application
to the CCDC, 12 Union Road, Cambridge CB2 1EZ, U.K. (fax
(+44) 1223 336033, e-mail deposit@ccdc.cam.ac.uk).
X-ray Crystallography. Single crystals of 1-4 were analyzed
at 150(2) K using graphite-monochromated Mo KR radiation and
a Nonius Kappa CCD diffractometer. Data collection and refinement
details are summarized in Table 1. The structures were solved using
SHELXS-9735 and refined using SHELXL-97.35 In 1, the asym-
metric unit was seen to contain one solvent THF molecule in
addition to one complex molecule. In addition to one molecule of
the carbene complex, the asymmetric unit in 2 was also seen to
contain half of a benzene molecule (disordered over two sites).
These disordered moieties are located proximate to a crystal-
lographic 2-fold rotation axis which serves to generate the remaining
solvent fragments. The asymmetric unit in 3 consists of half of
one molecule, the remaining portion being generated via a 2-fold
crystallographic rotation axis on which C2, H1, and Ru1 are located.
Acknowledgment. We thank Drs. Anneke Lubben and John
Lowe for mass spectrometry and NMR support, respectively.
We acknowledge Johnson Matthey plc for the loan of hydrated
RuCl3. Financial support was provided via a Doctoral Training
Award (to S.P.R. at the University of Bath), the Swiss National
Science Foundation, and the ETHZ.
Supporting Information Available: X-ray crystallographic files
in CIF format for complexes 1-4. This material is available free
of charge via the Internet at http://pubs.acs.org.
(35) Sheldrick, G. M. Acta Crystallogr. 1990, 467-473, A46. Sheldrick,
G. M. SHELXL-97, a Computer Program for Crystal Structure Refinement;
University of Go¨ttingen, Go¨ttingen, Germany, 1997.
OM070164P