Cleavage of F-C(sp2) bonds by MHR(CO)(PtBu 2Me)2 (M = Os and Ru; R = H, CH3 or Aryl): Product dependence on M and R

Article abstract of DOI:10.1016/j.poly.2005.08.012

Both MH(Ph)(CO)L₂ (L = P^tBu₂Me; M = Ru and Os) react with vinyl fluoride to form M-F bonds; however, Ru eliminates benzene, while Os eliminates ethylene. In contrast, Ru(H)₂(CO)L ₂ and Os(H)₂

Full text of DOI:10.1016/j.poly.2005.08.012

Polyhedron 25 (2006) 459–468
www.elsevier.com/locate/poly
Cleavage of F–C(sp2) bonds by MHR(CO)(PtBu2Me)2 (M = Os and
Ru; R = H, CH3 or Aryl): Product dependence on M and R
*
Dejian Huang, Kenton B. Renkema, Kenneth G. Caulton
Department of Chemistry, Indiana University, 800 E. Kirkwood, CHEM A250B, Bloomington, IN 47405-4001, USA
Received 12 May 2005; accepted 9 August 2005
Available online 4 October 2005
In celebration of the coming of age of Malcolm Harold Chisholm.
Abstract
Both MH(Ph)(CO)L2 (L = PtBu2Me; M = Ru and Os) react with vinyl fluoride to form M–F bonds; however, Ru eliminates
benzene, while Os eliminates ethylene. In contrast, Ru(H)2(CO)L2 and Os(H)2(CO)(1-butene)L2 both react with vinyl fluoride to
give ethylene and MHF(CO)L2. Ethylene production from both dihydrides is attributed to b-F migration to M from an MCH2CH2F
transient, while the unique behavior of RuH(Ph)(CO)L2 (giving the C–F oxidative addition product Ru(g1-vinyl)F(CO)L2) is attrib-
uted to the difficulty of achieving RuIV, and the ability of the strongly p-acidic vinyl fluoride to rapidly trigger reductive elimination
of benzene. The products of reaction of RuH(Ar)(CO)L2 with vinyl fluoride are redirected more towards ethylene formation when
Ar carries fluorine substituents. The reaction products of OsH(R)(CO)L2 with vinyl fluoride revert to R-H elimination when R is
methyl. Finally, the more p-acidic H2C@CF2 triggers very rapid CH4 elimination from OsH(CH3)(CO)L2; cleavage of the second
C–F bond yields the vinylidene OsF2(CCH2)(CO)L2. All selectivity is rationalized via the fate of the adduct MH(R)(C2H4 ꢀ nFn)-
(CO)L2.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Fluorocarbons; Ruthenium; Osmium; Organometallic; Mechanisms
1. Introduction
bond [26]. That is, kinetic selectivity is required [27–32].
In at least one case, C–F bond cleavage is thermodynam-
ically favored, but kinetically disfavored [33]. However,
rarely has there been a report of different selectivity for
reaction of a metal complex with vinyl fluoride versus aryl
fluoride. Such an example is documented here.
C–F bond cleavage is a goal for accomplishing cata-
lytic transformation of perfluoroalkanes (and arenes)
and Freons to valuable or environmentally benign mate-
rials [1–5]. This is also a topic of interest in organic synthe-
sis [6–19]. The early transition elements have a strong
tendency to cleave F–C(sp2) bonds [20–25]. A fundamen-
tal problem in C–F activation by soluble transition metal
complexes is selective cleavage of the C–F in preference to
the C–H bond in partially fluorinated alkanes and arenes
since the C–F bond is normally stronger than the C–H
2. Results
2.1. MH(Ph) Reactivity with H2C@CHF
(a) M = Os. The molecule OsH(Ph)(CO)L2 (L =
PtBu2Me) (1), is reported to be ‘‘triggered’’ by reaction
with fluoroarenes (C6H6 ꢀ nFn, with n = 1, 2, 5) at 25 ꢁC
to eliminate C6H6 and oxidatively add an arene C–H
*
Corresponding author. Tel.: +1 812 855 4798; fax: +1 812 855
8300.
E-mail address: caulton@indiana.edu (K.G. Caulton).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.08.012

460
D. Huang et al. / Polyhedron 25 (2006) 459–468
Ph
(L = PtBu2Me)
L
OC
Os
F
L
H
H
3
- C2H4
L
L
L
M = Os
M = Ru
CH2=CHF
OC
M
Ph
OC
M
Ph
L
C2H3
- C6H6
1
CH2CHF
2, M = Os
L
OC
Ru
F
L
4
Scheme 1.
bond, to yield OsH(ArF)(CO)L2 [34]. The reactions are
thus selective against C–F bond scission; indeed, C6F6
does not react. In contrast, 1 is now reported to react
with vinyl fluoride to ultimately produce a C–F bond-
cleaved product. Reaction of OsH(Ph)(CO)L2 with ex-
cess vinyl fluoride at ꢀ90 ꢁC in toluene (Scheme 1) gives
ture (Scheme 1). The 19F NMR spectrum of 4 shows a
broad triplet (3JPF = 22 Hz) and the 31P{1H} NMR
spectrum shows a doublet with the same JPF value.
1
The H NMR spectrum of 4 features an a-vinyl proton
at 8.3 ppm (ddd, JHH = 14.7 Hz, JHH = 7.5, JFH
=
6.9 Hz) with the b-protons at higher field (5.4 and
5.1 ppm). The low m(CO) value (1894 cmꢀ1) is consistent
with CO trans to F. For comparison, 4 can also be syn-
thesized from RuHF(CO)L2 and C2H2. Combination of
RuHF(CO)L2 and 1 atm C2H2 in benzene gives
Ru(C2H3)F(CO)L2 quantitatively in 30 min at room
temperature.
1
a p-adduct (2), OsH(Ph)(CO)L2(C2H3F). The H NMR
spectrum of 2 shows a hydride peak at ꢀ3.7 ppm as an
apparent triplet. The coordinated vinyl protons appear
at 2.7, 2.9 and 7.6 ppm and the 19F NMR signal of the
bound vinyl fluoride (ꢀ171 ppm) is shifted significantly
upfield, compared to that of free vinyl fluoride
(ꢀ113 ppm) [35]. The 31P{1H} NMR spectrum of this
adduct at ꢀ50 ꢁC is an AB quartet and the relatively
small J0PP = 162 Hz is indicative of two phosphines bent
significantly away from a ꢁ180ꢁ P–Os–P angle, consis-
tent with strong back donation to this olefin [35]. At
25 ꢁC, 2 reacts further (complete in 4 h) to release ethyl-
ene and form 3, OsPh(F)(CO)L2. The 19F NMR spec-
trum shows a triplet (2JPF = 28 Hz) at a chemical shift
(ꢀ202.1 ppm) consistent with F bonded to osmium
(not carbon), and 31P{1H} NMR shows a doublet with
the same splitting. The tBu groups are diastereotopically
inequivalent and they, as well as the PCH3 groups, are
virtual triplets consistent with structure 3. The mCO value
(1874 cmꢀ1) is low enough to be consistent with a push/
pull F ! COp* donation when these ligands are mutu-
ally trans. There are four (one of intensity 2) distinct phe-
nyl proton NMR signals, suggesting slow rotation of the
Ph around the Os–C(ipso) bond [36].
(c) Mechanism. We interpret these results without
invoking a wholly different mechanism for the reaction
of the Ru and Os species MH(Ph)(CO)L2 with vinyl
fluoride. The idea that an oxidant, including even an
electron deficient olefin like (NC)2C@C(CN)2, can trig-
ger reductive elimination is termed oxidatively induced
reductive elimination [37–41]. We suggest that the ab-
sence of detectable vinyl fluoride adduct for M = Ru is
of quantitative (i.e., a few kcal/mol) rather than qualita-
tive significance. Indeed, it serves as a reminder that Os
is a more potent p base than Ru, since back-bonding is
an important component of binding of the fluorinated
olefin. This difference in p-basicity can also be used to
interpret the distinct selectivities shown by Ru and Os.
In brief (Scheme 2), osmium is more tolerant to high
oxidation states, so the C–F oxidation product, contain-
ing OsIV, can be achieved. This seven-coordinate species
will be sufficiently persistent and nonrigid, to permit
isomerization of H to a site cis to the vinyl group; reduc-
tive elimination of ethylene follows. For M = Ru, g2
binding of p-acidic H2C@CHF triggers rapid reductive
elimination of H with C6H5 as the lowest energy process,
in order to avoid the high (versus Os) energy of RuIV;
the prompt character of these two events prohibits
establishing any inherent (i.e., thermodynamic) prefer-
ence for phenyl versus vinyl remaining on ruthenium.
That is, selectivity is truly kinetically controlled for Ru
(b) M = Ru. RuH(Ph)(CO)L2 also cleaves the C–F
bond of vinyl fluoride but it gives a different product.
Combination of RuH(Ph)(CO)L2 with 1 atm CH2 =
CHF in benzene1 gives quantitative formation of
Ru(CH@CH2)F(CO)L2 (4), after 12 h at room tempera-
1
No detectable amount of adduct is formed from RuH(Ph)(CO)L2
under 1 atm vinyl fluoride in d14-methylcyclohexane at ꢀ70ꢁ by 1H and
31P NMR spectroscopy.

D. Huang et al. / Polyhedron 25 (2006) 459–468
461
C6H6
+
H
L2(OC)M
H2C
H
Ph
M = Os
Ph
H
M = Ru
Ph
CHF
L2(OC)Os
L2(OC)Os
L2(OC)Ru
F
C2H3
C2H3
C2H3
F
F
A
-C2H4
Ph
L2(OC)Os
F
Scheme 2.
but probably not so for Os. Based on our earlier
evidence that M–F bond formation is thermodynami-
cally favored for the reactions of the various five-coordi-
nate species studied here [33], the metal dependent
products in Scheme 1 probably involve very small differ-
ences in reaction enthalpy (i.e., they differ by vinyl ver-
sus phenyl on the metal (Eq. (1)) but share the
production of a M–F bond). The different products
are thus best explained by being under kinetic control
via the distinct accessibility of redox changes at a 4d ver-
sus a 5d metal.
DGà for Ru, we discount it. In contrast, the known re-
dox differences of Ru and Os naturally account for the
observed selectivity difference via Scheme 2.
M(H)2 reactivity with H2C@CHF. A mechanism
which incorporates the adduct MHR(H2C@CHF)-
(CO)L2 also naturally explains the high rate and similar
products, for M = Ru and Os, when R = H, as will now
be described. The feature common to the reactions in
Scheme 1 is that the hydride ligand cannot react immedi-
ately with a vinyl fluoride ligand trans to itself, and thus
metal-dependent selectivity develops from within the ad-
duct. To create the contrasting situation of hydride cis to
the olefin, excess vinyl fluoride was reacted with Ru(H)2-
(CO)L2 [36]: immediately at ꢀ80 ꢁC ethylene and RuHF-
(CO)L2 are formed. We propose the reaction proceeds by
insertion of vinyl fluoride into the cis Ru–H bond, fol-
lowed by b-F migration (Scheme 3).
CH
F
2
H
HC
L (OC)M Ph
2
F
L (OC)Ru
2
+ H C=CH
vs.
2
L (OC)Os
2
+
F
H
H C
5
6
+
H
H C
3
2
To compare this dihydride reactivity of Ru to that for
Os, Os(H)2(1-butene)(CO)L2 [43,44] (as a source of the
currently unknown Os(H)2(CO)L2) was prepared from
Os(H)2(H2)(CO)L2 and 1-butene. This molecule reacts
with excess (19 equivalents) vinyl fluoride within 30 min
at 25 ꢁC in C6D6 to give ethylene and OsHF(CO)L2; since
this product molecule shows dynamic NMR effects from
binding olefin, identification is simplified by first remov-
ing all volatiles, then redissolving in benzene.
ð1Þ
In order to test for possible phosphine dissociation
at or prior to the rate determining step in the reaction
of MH(Ph)(CO)L2 with vinyl fluoride, a rate comparison
was made in the absence and presence of 2–5 equiva-
lents of free phosphine (PtBu2Me). For either M =
Ru or Os, the half-lives for product appearance were
observed to be comparable with and without added
L, eliminating phosphine dissociation as a mechanistic
component.
Thus, and in contrast to MH(Ph)(CO)L2, unsatu-
rated Ru and Os show analogous reactivity when a hy-
dride is adjacent to the empty coordination site.
Based on the mechanism previously deduced for reac-
tion of OsHCl(CO)(PiPr3)2 with RCCH [42], a direct
attack of the M–H bond on the olefin must also be con-
sidered here (Eq. (2)). Here, no prior g2-olefin adduct is
on the reaction path and the first M/C interaction is
concurrent with C/H bond formation.
2.2. Influence of R group identity in MH(R)(CO)L2
The essential feature of species A is that C2H3 and H
are not mutually cis because H, Ph, C2H3, and F are copla-
nar. Therefore, the different results seen for Ru and Os
were argued to occur because the unstable Ru(IV) inter-
mediate analogous to A would not allow time for rear-
rangement, followed by elimination of the most
thermodynamically favorable products, MF(Ar)(CO)L2
and olefin. The furthest extension of this mechanism,
where a Ru(IV) intermediate never exists, is represented
in Scheme 4.
CH2F
H
CHF
CH2
CH2
M
ð2Þ
M-F + C2H4
M
Since this is a path to M–F and ethylene, it might ex-
plain the results when M = Os, but not for Ru. Because
it is not clear why this mechanism would have higher

462
D. Huang et al. / Polyhedron 25 (2006) 459–468
H
H
H
H
L
L
L
L
CH2=CHF
-C2H4
OC
Ru
H
OC
Ru
F
OC
Ru
OC
Ru
H
L
L
L
L
F
CH2=CH F
Scheme 3.
In order to understand what role M–R bond strength
cal position. The hydride chemical shift is far upfield
(ꢀ33.2 ppm). The methyl 1H NMR signal (integrated to
intensity 3) is a triplet at 0.46 ppm. The t-butyl signals
are diastereotopic virtual triplets and the 31P NMR spec-
trum shows one sharp singlet. In benzene at 22 ꢁC, 5
undergoes slow conversion to OsH(Ph)(CO)L2. Species
5 thus has a weaker Os–C bond than OsH(Ph)(CO)L2.
Compound 5 is completely consumed by excess vinyl
fluoride at ꢀ75 ꢁC in d8-toluene; two new species were
observed by 19F NMR. The 31P NMR spectrum of one
of these showed an AB pattern (JPP = 161 Hz). 1H
NMR gave two defining signals, a hydride signal at
ꢀ6.3 ppm (d of d) and signal intensity 3 at ꢀ1.1 ppm (as-
signed to Os–CH3). These spectroscopic features are con-
sistent with assignment of (Eq. (3)) the most abundant
primary product as the simple adduct OsH(CH3)-
(CO)L2(C2H3F).
plays in these reactions, we synthesized RuH(2-C6H4F)-
(CO)L2 and RuH(C6F5)(CO)L2 by reacting RuH(Ph)
(CO)L2 with monofluorobenzene and pentafluoroben-
zene, respectively. We expect that these species will have
greater thermal stability against arene elimination with
increasing number of fluorines on the aryl ring since
OsH(2,6-C6F2H3)(CO)L2 persists unchanged after 30 h
at 70 ꢁC in d12-cyclohexane, but OsH(C6H5)(CO)L2
decomposes to free benzene, phosphine and unidentified
osmium products under the same conditions. Previous
DFT-calculations on OsH(C6H5)(CO)(PH3)2 showed
that p donation was partially responsible for restricted
rotation about the M–C(ipso) bond. The calculated
and observed thermodynamic preference for metal–aryl
complexes with fluorine ortho to the metal suggest that
fluorines on the aryl ring increase the amount of p dona-
tion from a fluoroaryl ring to a metal.
OsHðCH3ÞðCOÞL2 þ H2C@CHF
(a) Ru–ArF. When RuH(2-C6H4F)(CO)L2 was re-
acted with one equivalent of vinyl fluoride for 20 h at
50 ꢁC, the products, Ru(C2H3)F(CO)L2 and C6H5F,
are analogous to those in Eq. (2), i.e., aryl/H reductive
elimination. Reaction of the less oxidizable RuH(C6F5)-
(CO)L2 with less than one equivalent C2H3F for 7 days
at 85 ꢁC yields Ru(C2H3)F(CO)L2, C6F5H, Ru(C6F5)F-
(CO)L2, and C2H4. These last two products therefore
indeed indicate that reactions of both types in Scheme
2 compete for this more stable ruthenium hydrido-
fluoroaryl reagent, consistent with Ru–C bond strength
influencing the decay mode of the intermediate.
(b) Os–CH3. Continuing this hypothesis, an osmium
species with a weaker Os–C bond than Os–C6H5 should
change reaction selectivity. To that end, OsH(CH3)-
(CO)L2 (5), was synthesized by reaction of OsHCl-
(CO)L2 with one equivalent of MeLi. Centrifugation of
the solution most efficiently removed the LiCl co-product.
The NMR signatures of 5 are consistent with other five-
coordinate osmium complexes where hydride is in the api-
*
)
OsHðCH3ÞðCOÞL2ðC2H3FÞ
RT
OsFðCH ÞðCOÞL þ H C@CH
ð3Þ
ƒƒ!
3
2
2
2
Warming the mixture to ꢀ15 ꢁC increased the rate of
olefin exchange sufficiently to cause the 19F NMR sig-
nals at ꢀ169 ppm for bound olefin to broaden nearly
into the baseline. Significant conversion of this olefin
adduct to the final product did not occur until room
temperature, but this is faster than the correspon-
ding reaction of OsH(Ph)(CO)L2. A 19F NMR triplet
(ꢀ198 ppm, JFP = 27 Hz), a 31P{1H} NMR doublet
(26.0 ppm, JPF = 27 Hz), the loss of the hydride signal,
and the production of ethylene are all consistent with
assignment of the new compound as OsF(CH3)(CO)L2.
This represents reactivity analogous to that of
OsH(Ph)(CO)L2 with vinyl fluoride.
The amount and spectral features of the second low
temperature product change very little upon warming
the sample from ꢀ45 to 20 ꢁC. Over those temperatures,
H
L
L
L
OC
-HPh
M
OC
L
M
Ph
OC
L
M
F
F
L
F
Scheme 4.

D. Huang et al. / Polyhedron 25 (2006) 459–468
463
the 31P{1H} NMR spectrum showed an AM pattern
(Dd = 32 ppm) with a JPP of 148 Hz. One of the phos-
phorus nuclei showed coupling to fluorine (JPF = 15 Hz)
whose magnitude is consistent with F on Os. This fluo-
rine is detected at ꢀ195 ppm as a doublet of multiplets.
AM patterns with large Dd are typical for metallated al-
kyl ligands on phosphines; we propose structure 6. The
presence of this second product where the osmium com-
plex has lost methane, HR, shows the competitive occur-
rence of a second mechanism, that used by Ru in
Scheme 2, prior to activation of a C–F bond. This spe-
cies declines in intensity as the temperature is raised
and ultimately disappears from both 31P and 19F
NMR spectra.
ond fate for OsH(Me)(CO)L2, following olefin-induced
reductive elimination of methane. The primary product
would then be zerovalent, unsaturated 7 (Scheme 5), in
which oxidative addition of a t-Bu C–H bond would
permit hydrogen migration to vinyl fluoride, then fluo-
rine migration to Os, with liberation of ethylene.
The detection of a second competitive reaction chan-
nel for OsHMe(CO)L2 in reacting with vinyl fluoride
thus links the ruthenium chemistry (RuH(Ph)(CO)L2)
to that of osmium; the more facile elimination of H with
an sp3 carbon (versus sp2 in OsH(Ph)(CO)L2) makes this
oxidatively induced reductive elimination now detect-
able (but not dominant) for OsHMe(CO)L2.
2.3. A more oxidizing olefin
CMe2
H2C
(a) Os–CH3. The gem-difluoro olefin H2C@CF2 pro-
vides an additional test of mechanism. An insertion
mechanism for reaction of H2C@CF2 with 5 would yield
vinyl fluoride (Scheme 6). If, on the other hand, this
more p-acidic difluoro olefin promptly triggers methane
elimination, then the first C–F oxidative addition to
Os(0) could be followed by a second F migration
(Scheme 7). Reaction of OsH(CH3)(CO)L2 with gem-
difluoroethylene at 0 ꢁC with subsequent slow warming
to room temperature, then removal of excess olefin, gave
75% yield of product 8 with 100% conversion of 5. The
31P{1H} NMR spectrum of 8 is a doublet of doublets
(JPF = 41, 25 Hz). 19F NMR revealed an AB pattern
due to inequivalent F on Os. The lower field doublet
(JFF = 143 Hz) also showed triplet coupling to phospho-
rus (JFP = 25 Hz), while the lines of the higher field dou-
blet were each triplets of triplets, due to two phosphorus
PtBuMe
OC Os
L
F
6
Detection of this species is especially important be-
cause it has the stoichiometry of Os(CO)L2 minus one
H and plus one F. It is thus a plausible product of a sec-
OsH(Me)(CO)L2 + H2C=CHF
Os(CO)(CH2=CHF)L2 + CH4
7
CMe2
H2C
PtBuMe
PtBuMe
C2H4 +
OC Os
L
F
L(OC)
Os
1
(JPF = 41 Hz) and two protons (JFH = 7 Hz). H NMR
H2C
showed the absence of a hydride chemical shift as well as
the appearance of a new signal at 2.0 ppm (vinylidene
CH2), which was a doublet of triplets (JHF = 7 Hz,
6
CH2F
Scheme 5.
Me
H
Me
Os
L
L
L
F
OC
L
Os
F
CH2
CF2H
OC
Os Me + H2C=CF2
OC
L
L
5
Scheme 6.
H
L
F
F
H
L
F
CH2
-HMe
(OC)L2Os
F
Os C
C
Oc
L
Os Me
F
F
L
H
CO
8
Scheme 7.

464
D. Huang et al. / Polyhedron 25 (2006) 459–468
F
H
L
F
H
H
L
F
-HR
R=Me
adduct
+
OC
L
M
R
M
C
L
C
F
CO
B
R=Ph
R
L
OC
L
M
F
C
Scheme 8.
JHP = 3 Hz). 13C{1H} NMR showed the b-carbon signal
at 94 ppm as a doublet (JCF = 16 Hz).
factors influencing the metal-dependence. It is also
remarkable that benzene loss from RuH(Ph)(CO)L2 is
followed by oxidative addition of the C–H bond of par-
tially fluorinated arene [33], but of the C–F bond of vi-
nyl fluoride. It is noteworthy that both metals show
kinetic selectivity (C–H cleavage) when reacting with
fluorinated arenes to give MH(ArF)(CO)L2 but thermo-
dynamic selectivity (M–F bond formation) when react-
ing with fluorinated olefins.
An osmium difluoride product is consistent with an
intermediate with fluorine located a to the metal because
such species exhibit a-fluoro migration. The ‘‘prompt’’
elimination of H–CH3 in Scheme 7 contrasts to the reac-
tion of OsH(Ph)(CO)L2 with vinyl fluoride, and may be
attributed to the more oxidizing (cf. p-acid) character of
H2C@CF2 (versus H2C@CHF).
(b) Os–Ph. To test the influence of Os–C(sp3) versus
C(sp2) on reactivity, the reaction of OsH(Ph)(CO)L2
with excess H2C@CF2 was studied. This yielded primar-
ily Os(Ph)F(CO)L2 on the same time scale as vinyl fluo-
ride; only a trace amount of OsF2(CO)(CCH2)L2 forms.
This result further illustrates how the energetics of HR
elimination from the proposed M(IV) intermediate af-
fects the outcome of the reaction (Scheme 8). When
HR elimination is the fastest process from the adduct,
then metal difluoride B would result. However, if rear-
rangement (to hydride cis to olefin) and elimination of
the vinyl species are faster, five-coordinate OsRF(CO)L2
(C), forms. Clearly, the latter is favored for osmium: the
Os–Ph bond persists through reaction with both
H2C@CHF and H2C@CF2.
In a sense, this reaction of RuH(Ph)(CO)L2 as a
‘‘Ru0(CO)L2 equivalent’’ is analogous to that of ele-
mental magnesium, to generate a Grignard reagent
by C–F oxidative addition [45]. In contrast, in both
dihydride cases reported here, the net reaction is
M–H/ C–F exchange, but apparently by a b-F migra-
tion mechanism.
This work began by raising the question of the curi-
ous selectivity for C–H over C–F scission in reaction of
OsH(Ph)(CO)L2 with partially fluorinated arenes.
However, vinyl fluoride substrate shows quite the
opposite selectivity, and what was discovered here is
contrasting metal selectivity: Ru versus Os. The ques-
tion of reversion to ‘‘normal’’ selectivity for C–F scis-
sion with fluoro olefins (cf. fluoroarenes) probably
relates to the greater ease of binding olefins (versus are-
nes) to metals, together with the very different ability
of metal to attack F–C(H)CH2 versus F–C(CH)2 (i.e.,
arene) moieties.
3. Conclusion
We have demonstrated here several C–F bond cleav-
age reactions of vinyl fluoride by five-coordinate hy-
drides MHR(CO)L2 (R = Ph, CH3, H; M = Os, Ru).
The reaction products are highly dependent on the iden-
tity of the metal when R = Ph. For Os, Os–H/C–F
‘‘exchange’’ is the dominant pathway, while for Ru
and R = Ph, the reaction features reductive elimination
of C6H6, followed by C–F bond cleavage of vinyl fluo-
ride. The facility for H-Ph formation and the relative
stability of (II versus IV) oxidation states are the two
4. Experimental
4.1. General procedures
All manipulations were performed using standard
Schlenk techniques or in an argon filled glovebox unless
otherwise noted. Solvents were distilled from Na, Na/
˚
benzophenone, CaH2, or 4 A molecular sieves, degassed

D. Huang et al. / Polyhedron 25 (2006) 459–468
465
prior to use, and stored in air-tight vessels. OsHCl
(CO)(PtBu2Me)2 [46], OsH(Ph)(CO)(PtBu2Me)2 [34],
RuHF(CO)(PtBu2Me)2 [47], Ru(H)2(CO)(PtBu2Me)2
[36] and RuH(Ph)(CO)(PtBu2Me)2 [36] were prepared
according to published procedures. All other reagents
were purchased from commercial vendors and used as
received after drying/degassing when necessary. 1H
NMR chemical shifts are reported in ppm relative to
protio impurities in the deuterated solvents; 31P (always
proton-decoupled) and 19F spectra are referenced to
external standards of 85% H3PO4 and CFCl3, respec-
tively (both at 0 ppm). NMR spectra were recorded with
a Varian Gemini 2000 (300 MHz 1H; 121 MHz 31P;
75 MHz 13C, 282 MHz 19F), a Varian Unity Inova
the headspace was charged with acetylene gas (1 atm).
The mixture was stirred at room temperature for
30 min before the volatiles were removed under vac-
uum. The residue was dissolved in pentane, filtered
through a Celite pad and concentrated to ca. 2 mL.
After cooling the solution at ꢀ40 ꢁC for one day, dark
orange crystals were obtained. Yield: 120 mg (76%).
1H NMR (C6D6, 20 ꢁC, 300 MHz): 1.20 (vt, N = 12.5,
18H, PC(CH3)3), 1.25 (vt, 18H, N = 12 Hz, PC(CH3)3),
1.21 (vt, 6H, N = 5.9, PCH3), 5.10 (dt, JHH = 14.5,
JPH = 2.0 Hz, 1H b-H(vinyl)), 5.45 (dt, JHH = 6.4 Hz,
JPH = 2.4 Hz, 1H, b-vinyl), 8.30 (doublet of apparent
triplets, 1H, JHH = 14.5 Hz, JHH = 7.5 Hz, JHF
=
6.9 Hz, a-H of vinyl). 13C{1H} NMR (toluene-d8,
75 MHz, 20 ꢁC): 3.16 (vt, N = 15 Hz, PCH3), 29.7,
29.8 (s, PC(CH3)3), 35.4, 35.5 (s, PC(CH3)3), 117.5 (s,
@CH2), 156.3 (t, J = 20.3 Hz, Ru–CH). 31P{1H}
NMR: 41.2 (d, JPF = 22 Hz). 19F NMR: ꢀ214 (t,
JPF = 22 Hz). IR (C6D6): 1894 (m(CO)).
1
instrument (400 MHz H; 162 MHz 31P; 101 MHz 13C,
376 MHz 19F), or a Varian Unity Inova instrument
1
(500 MHz H, 126 MHz 13C). Infrared spectra were re-
corded on a Nicolet 510P FT-IR spectrometer.
4.2. Os(Ph)F(CO)(PtBu2Me)2
4.5. Reaction of RuH(Ph)(CO)L2 with vinyl fluoride
An NMR tube containing OsH(Ph)(CO)(PtBu2Me)2
(16.5 mg, 2.68 · 10ꢀ5 mol) in 500 lL d8-toluene had
200 Torr (7.7 · 10ꢀ4 mol) of vinyl fluoride condensed
into it. At low temperature the g2-adduct formed: diag-
nostic 1H NMR (C7D8, ꢀ90 ꢁC) ꢀ3.7, (t, 1H, OsH,
JPH = 29 Hz); 2.7, (d, 1H, CCH, JHF = 20.4 Hz); 2.9
(d, 1H, CCH, JHF = 22 Hz); 7.54, (d, 1H, CCH,
JFH = 72.0 Hz). 31P NMR (C7D8, ꢀ90 ꢁC) ꢀ2.5, (AB,
JPP = 162 Hz). 19F(C7D8, ꢀ90 ꢁC) ꢀ171.3 (dt, 1F,
CCF, JFH = 73 Hz, JFH = 20 Hz). Conversion to the fi-
nal product did not occur until 10 ꢁC and was complete
within 4 h at room temperature. The 1H NMR detection
of ethylene confirmed product identity. 1H NMR (C7D8,
20 ꢁC) 1.00, (vt, 18H, OsPCCH3, JPH = 5.8 Hz); 1.04,
(vt, 18H, PCCH3, JPH = 5.8 Hz); 1.29, (broad s, 6H,
PCH3); 6.39, (t, 1H, Ar-H, JPH = 6.0 Hz); 6.5, (t, 2H,
Ar-H, JHH = 6 Hz); 7.32, (d, Ar-H, JHH = 6 Hz); 7.64,
(d, Ar-H, JHH = 6.0 Hz). 31P NMR (C7D8, 20 ꢁC)
26.5, (d, 2P, JPF = 28 Hz). 19F(C7D8, 20 ꢁC) ꢀ202.1 (t,
RuH(Ph)(CO)(PtBu2Me)2 (10 mg, 0.019 mmol) was
dissolved in C6D6 (0.5 mL) and degassed by three
freeze–pump–thaw cycles. To the tube, C2H3F (1 atm)
was charged. The mixture was agitated for 12 h. NMR
spectroscopies reveal clean formation of Ru(C2H3)(F)
(CO)L2 by comparison to data in the preceding
experiment.
4.6. Reaction of RuH(Ph)(CO)(PtBu2Me)2 with vinyl
fluoride in the presence of added phosphine ligand
In an NMR tube, RuH(Ph)(CO)L2 (10 mg,
0.019 mmol) and PtBu2Me (15 mg, 5 eq.) were dissolved
in cyclohexane-d12. The solution was degassed and the
headspace of the tube was charged with 1 atm vinyl
fluoride. After 12 h at room temperature, RuH(Ph)-
(CO)L2 was completely consumed and Ru(C2H3)F-
(CO)L2 was formed as revealed by its 31P{1H} NMR
spectrum.
1F, CCF, JFP = 28 Hz) m(CO) = 1874 cmꢀ1
.
4.3. Reaction of OsH(Ph)(CO)(PtBu2Me)2 + C2H3F in
the presence of PtBu2Me
4.7. Os(H)2(g2-1-butene)(CO)(PtBu2Me)2
Reaction of OsH2(H2)(CO)(PtBu2Me)2 (5.6 mg,
1.04 · 10ꢀ5 mol) with 1-butene (100 Torr, 6.95 ·
10ꢀ5 mol) in C6D6 at room temperature gives the title
compound within 5 min. The room temperature NMR
signals are broadened by dynamic equilibrium. 1H
NMR (C6D6, 293 K) ꢀ11.2 (t, OsH, 1H, JPH = 23 Hz);
ꢀ8.66 (t, OsH, 1H, JPH = 33.5 Hz); 0.86 (t, CH2CH3,
3H, JHH = 4 Hz); 1.26 (vt, PCCH3, 18H, JPH = 6.3 Hz);
1.28 (vt, PCCH3, 18H, JPH = 6.3 Hz); 1.62 (m,
CH2CH3); 2.2 (br s, vinyl CH, 1H); 2.6 (br s, vinyl
CH, 1H); 3.2 (br s, vinyl CH, 1H). 31P NMR (C6D6,
293 K) 29.6, 29.9 (AB, JPP = 148 Hz).
When OsH(Ph)(CO)(PtBu2Me)2 (10.5 mg, 1.70 ·
10ꢀ5 mol) was dissolved in 500 lL C6D6 and reacted
with two equivalents PtBu2Me and C2H3F (600 Torr,
5.2 equivalents) the reaction reached completion in
4 h. A similar time scale was observed in the absence
of free phosphine.
4.4. Ru(C2H3)F(CO)(PtBu2Me)2
RuHF(CO)L2 (150 mg, 0.32 mmol) was dissolved in
diethyl ether (3 mL). The solution was degassed and

466
D. Huang et al. / Polyhedron 25 (2006) 459–468
4.8. Reaction of OsH2(g2-1-butene)(CO)(PtBu2Me)2
with C2H3F
4.11. Reaction of RuH(2-C6FH4)(CO)(PtBu2Me)2 with
vinyl fluoride
To OsH2(g2-1-butene)(CO)(PtBu2Me)2 (1.83 · 10ꢀ5
mol) was added C2H3F (150 Torr, 19 equivalents);
OsHF(g2-C2H3F)(CO)(PtBu2Me)2 was formed within
30 min. The signals for this species were broad due to
exchange of olefin. The species was identified by 1H
NMR (C6D6, 293 K); 2.8, (br s, C2H3F); ꢀ3.1 (br s,
OsH) and 31P NMR (C6D6, 293 K): 24.5 (br s). Evacu-
ation of the excess olefin left OsHF(CO)(PtBu2Me)2.
1H NMR (C6D6, 293 K) ꢀ32.2 (td, OsH, 1H,
JPH = 13 Hz, JHF = 8.7 Hz); 1.20 (vt, PCCH3, 18H,
JPH = 6.9 Hz); 1.22 (vt, PCCH3, 18H, JPH = 6.9 Hz).
31P NMR (C6D6, 293 K) 44.78 (d, JPF = 26 Hz). 19F
NMR (C6D6, 293 K): ꢀ184.6 (t, JFP = 26 Hz).
RuH(2-C6FH4)(CO)(PtBu2Me)2 (10 mg, 1.8 · 10ꢀ5
mol) was dissolved in C6D6 (0.5 mL) and degassed by
three freeze–pump–thaw cycles. To the NMR tube, 400
Torr vinyl fluoride was charged. The resulting mixture
was heated at 50 ꢁC for 20 h to give Ru(C2H3)F(CO)
(PtBu2Me)2 and fluorobenzene.
4.12. RuH(C6F5)(CO)(PtBu2Me)2
The same procedure as RuH(2-C6FH4)(CO)-
(PtBu2Me)2 was followed except C6F5H was used in-
stead of C6H5F. Alternatively, it can be prepared from
reaction of RuHF(CO)(PtBu2Me)2 with Me3SiC6F5 in
the presence of a catalytic amount of CsF.
4.9. Reaction of Ru(H)2(CO)(PtBu2Me)2 with vinyl
fluoride
4.13. Reaction of RuH(C6F5)(CO)(PtBu2Me)2 with
vinyl fluoride
Ru(H)2(CO)(PtBu2Me)2 (10 mg) in toluene-d8
(0.5 mL) in an NMR tube was freeze–pump–thaw de-
gassed, and the headspace of the NMR tube was
charged with vinyl fluoride (1 atm) at ꢀ80 ꢁC. The tube
was transferred to a precooled NMR probe for observa-
tion. At ꢀ80 ꢁC, no Ru(H)2(CO)L2 but only RuHF
(CO)L2 was detected by its 31P{1H} NMR spectrum
(52.5 ppm, doublet JPF = 20 Hz). The volatiles of the
reaction mixture were vacuum transferred to another
NMR tube where the 1H NMR spectrum revealed ethyl-
ene (5.34, singlet).
In an NMR tube, RuH(C6F5)(CO)(PtBu2Me)2
(10 mg, 0.016 mmol) was dissolved in C6D6 (0.5 mL)
and degassed by three freeze–pump–thaw cycles. To
the tube, vinyl fluoride (400 mm Hg) was added. The
mixture was heated at 85 ꢁC for three days to give
(based on 31P{1H} NMR integration) conversion to
RuF(C6F5)(CO)(PtBu2Me)2 (85%) and Ru(C2H3)(F)
(CO)(PtBu2Me)2 (15%). Addition of CsF to the NMR
tube was necessary to resolve all couplings. Spectro-
1
scopic data for RuF(C6F5)(CO)(PtBu2Me)2: H NMR
(400 MHz, C6D6, 20 ꢁC) 0.92 (vt, 13 Hz, 18H, PCH3,);
0.99 (vt, 6.5 Hz,18H, PCCH3,); 1.22 (broad, 6H,
PCCH3). 31P{1H} NMR (C6D6, 20 ꢁC): 42.7 (d, 2P,
JPF = 24.6Hz). 19F NMR (376.3 MHz): ꢀ111.5 (dd,
JFRuF = 53.3 Hz, JFF = 28.8 Hz, 1F, o-ArF); ꢀ113.7
(d, JFF = 26.5 Hz, 1F, o-ArF,); ꢀ162.3 (dt, JFF = 53 Hz,
JPF = 25 Hz, Ru–F), ꢀ164.4 (dd, JFF = JFF = 21 Hz,
para-F), ꢀ164.9 (dddd, JFF = 26.2, 21, 5, 5 Hz, meta-
F); ꢀ167.4 (dddd, JFF = 28, 23, 5, 5 Hz, meta-F). The
volatiles of the reaction mixture were vacuum trans-
4.10. RuH(2-C6FH4)(CO)(PtBu2Me)2
RuH(Ph)(CO)(PtBu2Me)2 (200 mg, 0.38 mmol),
cyclohexane (10 mL), and fluorobenzene (1 mL) were
stirred together for 18 h. After removal of the volatiles,
the residue was extracted with pentane. The pentane
solution was filtered through a Celite pad, concentrated
to ca. 3 mL, and cooled to ꢀ78 ꢁC for 2 h to give yellow
crystals after 12 h. The crystals were filtered, washed
with pentane and dried in vacuo to yield 125 mg
(70%) of the title compound. Newly prepared product
contains two rotamers about the Ru–Aryl bond, with
10:6 ratio based on NMR integration of the PCH3
peaks. Spectroscopic data for the major isomer: 1H
NMR (C6D6, 20 ꢁC) ꢀ28.7 (td, JPH = 19.2,
JFH = 7.6 Hz, 1H, RuH); 0.70 (vt, 5.5 Hz, 6H, PCH3);
1.13 (vt, 13 Hz, 18H, PCCH3); 1.20 (vt, 12.7 Hz, 18H,
PCCH3); 6.9, 7.1, 7.6 (m, 4H, ArH). 31P NMR (C6D6,
20 ꢁC) 57.0 (s). 19F (C6D6, 20 ꢁC) ꢀ96.7(s). Minor
1
ferred to another NMR tube and H and 19F NMR
spectra showed C2H4 and C6F5H.
4.14. OsH(CH3)(CO)(PtBu2Me)2
A solution containing 40.5 mg (7.04 · 10ꢀ5 mol)
OsHCl(CO)(PtBu2Me)2 in 3 mL of pentane was prepared
in a centrifuge tube. Dropwise addition of 49.0 lL
(7.11 · 10ꢀ5 mol) MeLi solution caused a gradual dark-
ening of the solution concurrent with the appearance of
a white suspension. The solution was centrifuged and
the supernate was pipetted to a Schlenk flask. The solvent
was then removed to leave an orange-red solid. 1H NMR
(C6D12, 20 ꢁC) ꢀ33.3, (t, 1H, OsH, JPH = 15.1 Hz); 0.46
(t, 3H, OsCH3, JPH = 7.2 Hz); 1.18 (vt, 18H, PCCH3,
isomer: 1H NMR: ꢀ27.2 (td, JPH = 20 Hz, JHF
=
5.2 Hz, 1H, Ru–H), 0.66 (vt, 5.5 Hz, PCH3), 1.09 (vt,
12 Hz, 18H, PC(CH3)3), 1.19 (vt, 13 Hz, 18H,
PC(CH3)3), 6.87, 7.03, 7.55 (4H, Ar). 31P{1H} NMR:
57.1 (s). 19F NMR: ꢀ84.5 (s).

D. Huang et al. / Polyhedron 25 (2006) 459–468
467
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(t, 6H, PCH3, JPH = 2.8 Hz). 31P NMR (C6D12, 20 ꢁC)
36.5, IR(C6D6): 1864(mCO).
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4.15. Os(CH3)F(CO)(PtBu2Me)2
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The reaction was run in a sealed NMR tube containing
9.2 mg OsH(CH3)(CO)(PtBu2Me)2 (1.658 · 10ꢀ5 mol)
with 100 Torr vinyl fluoride (6.786 · 10ꢀ5 mol) in d8-
toluene. At ꢀ75 ꢁC, the adduct OsH(Me)(g2-C2H3F)
(CO)(PtBu2Me)2 was formed. Its diagnostic spectral fea-
1
tures were: H NMR (C7D8, ꢀ75 ꢁC) ꢀ6.3 (1H, OsH);
ꢀ1.1 (3H, OsCH3); 2.9 (d, 1H, C@CH, JPH = 22.0 Hz);
3.2 (m, 1H, C@CH); 6.3 (1H, C@CH). 31P NMR (C7D8,
ꢀ75 ꢁC): 15.2, 12.7 (AB, 2P, JPP = 161Hz). 19F(C7D8,
ꢀ75 ꢁC) ꢀ170.0 (dt, 1F, CCF, JFH = 73Hz, JFH
=
20 Hz). Conversion to the final product (the title com-
pound) occurred at 20 ꢁC; its spectroscopic features were:
1H NMR (C7D8, 20 ꢁC) ꢀ1.1 (3H, OsCH3); 1.28 (vt, 18H,
OsPCCH3, JPH = 6Hz); 1.30 (vt, 18H, PCCH3,
JPH = 6Hz); 1.86 (6H, PCH3). 31P NMR (C7D8, 20 ꢁC)
26.0, (d, 2P, JPF = 27 Hz). 19F (C7D8, 20 ꢁC) ꢀ198.0 (t,
1F, OsF, JFP = 27Hz).
4.16. OsF2(CCH2)(CO)(PtBu2Me)2
When 8.5 mg (1.53 · 10ꢀ5 mol) of OsHMe(CO)-
(PtBu2Me)2 was warmed slowly with 25 equivalents
(3.83 · 10ꢀ4) of gem-difluoroethylene, OsF2(CCH2)-
(CO)(PtBu2Me)2 formed in 60% yield. Following vacuum
removal of excess C2H2F2, and other volatiles, the diag-
nostic spectroscopic signals of the major product were:
1H NMR (C6D6, 20 ꢁC) 1.31 (vt, 36H, PCCH3,
JPH = 7.0 Hz); 1.44 (vt, 6H, OsPCH3, JPH = 4.1 Hz);
2.01 (dt, 2H, CCH2, JFH = 7 Hz, JPH = 3 Hz). 13C
NMR (C6D6, 20 ꢁC) 3.6 (t, 2C, PCH3, JCP = 5 Hz); 29.7
(s, 6C, PCCH3): 29.5 (s, 6C, PCCH3); 36.2 (t, 2C, PCCH3,
JPC = 10.4); 36.4 (t, 2C, PCCH3, JPC = 10.4); 94.8 (d, 1C,
OsCC, JCF = 16). 31P NMR (C6D6, 20 ꢁC) 34.65 (dd, 2P,
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JPF = 41.9 Hz,
J
PFÔ = 25.1 Hz). 19F (C6D6, 20 ꢁC)
ꢀ277.45 (dt, 1F, OsF, JFF = 143, JFP = 25 Hz); ꢀ278.6
(dtt, 1F, OsF, JFF = 143, JFP = 41, JHF = 7 Hz).
Acknowledgment
This work was supported by the US National Science
Foundation.
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