C-F Bond Activation of P(C6F5)3 by Ruthenium Dihydride Complexes: Isolation and Reactivity of the missing Ru(PPh3)3H(halide) Complex, Ru(PPh3)3HF

Article abstract of DOI:10.1021/acs.inorgchem.8b02286

The major product of the reaction between Ru(IMe₄)₂(PPh₃)₂H₂ (1; IMe₄ = 1,3,4,5-tetramethylimidazol-2-ylidene) and P(C₆F₅)₃ (PCF) is the five-coordinate complex Ru(IMe₄)₂(PF₂{C₆F₅})(C₆F₅)H (2), which is formed via a complex series of C-F/P-C bond cleavage and P-F bond formation steps. In contrast, hydrodefluorination of all six ortho C-F bonds in PCF occurs with Ru(PPh₃)₄H₂ to afford Ru(PPh₃)₃HF (3). NaBAr^F₄ abstracted the fluoride ligand in 3 to give [Ru({η⁶-C₆H₅}PPh₂)(PPh₃)₂H][BAr^F₄], while B₂pin₂ reacted with 3 in C₆D₆ to yield a mixture of [Ru({η⁶-C₆D₆)(PPh₃)₂H]⁺ and Ru(PPh₃)₄H₂. The treatment of 3 with HBpin (5 equiv) and HSiR₃ (R = Et, Ph; 2 equiv) afforded Ru(PPh₃)₃(σ-HBpin)H₂ and Ru(PPh₃)₃(SiR₃)₃H₃, respectively. No stable substitution products were generated when 3 was reacted with Me₃SiX (X = CF₃, C₆F₅).

Full text of DOI:10.1021/acs.inorgchem.8b02286

Article
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/IC
C−F Bond Activation of P(C F ) by Ruthenium Dihydride
6
5 3
Complexes: Isolation and Reactivity of the “Missing”
Ru(PPh ) H(halide) Complex, Ru(PPh ) HF
3
3
3 3
Mateusz K. Cybulski, Caroline J. E. Davies, John P. Lowe, Mary F. Mahon, and Michael K. Whittlesey*
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
*
S Supporting Information
ABSTRACT: The major product of the reaction between Ru-
IMe ) (PPh ) H (1; IMe = 1,3,4,5-tetramethylimidazol-2-ylidene) and
(
4
2
3 2
2
4
P(C F ) (PCF) is the five-coordinate complex Ru(IMe ) (PF {C F })-
6
5 3
4 2
2
6 5
(
C F )H (2), which is formed via a complex series of C−F/P−C bond
6
5
cleavage and P−F bond formation steps. In contrast, hydrodefluorination of
all six ortho C−F bonds in PCF occurs with Ru(PPh ) H to afford
3
4
2
F
Ru(PPh ) HF (3). NaBAr abstracted the fluoride ligand in 3 to give
3
3
4
6
F
[
Ru({η -C H }PPh )(PPh ) H][BAr ], while B pin reacted with 3 in C D
6 5 2 3 2 4 2 2 6 6
6
+
to yield a mixture of [Ru({η -C D )(PPh ) H] and Ru(PPh ) H . The treatment of 3 with HBpin (5 equiv) and HSiR (R =
6
6
3 2
3 4
2
3
Et, Ph; 2 equiv) afforded Ru(PPh ) (σ-HBpin)H and Ru(PPh ) (SiR ) H , respectively. No stable substitution products were
3
3
2
3 3
3 3
3
generated when 3 was reacted with Me SiX (X = CF , C F ).
3
3
6 5
INTRODUCTION
metal centers has been probed quite extensively, predom-
■
34−38
inantly with catalytic applications in mind,
there are a
Transition-metal hydride complexes have proven to be
1
−11
small number of reports that show that PCF (or derivatives
valuable for effecting the cleavage of C−F bonds.
In
thereof) are susceptible to C−F activation by nucleophilic
many cases, the precise mechanism(s) underpinning the C−F
39−42
12−18
ligands on metal centers.
To the best of our knowledge,
activation chemistry remain(s) to be fully established.
these nucleophilic ligands have not included hydrides.
Herein, we report that PCF undergoes a complex series of
C−F/P−C bond cleavage and P−F bond formation processes
However, on the basis of examples where detailed mechanistic
studies have been undertaken, the hydride ligands either
behave innocently, for example, by undergoing elimination
from the metal (in the case of dihydrides, through either
thermally or photochemically induced reductive elimination)
to generate coordinatively unsaturated metal species that then
with 1 to yield the unusual PF (C F ) complex Ru-
2
6 5
(
IMe ) (PF {C F })(C F )H (2). In contrast, HDF of all six
4 2 2 6 5 6 5
o-C−F bonds takes place with the tetrakis-
19,20
(
(
triphenylphosphine)ruthenium dihydride complex Ru-
PPh ) H to yield Ru(PPh ) HF (3), the last of the well-
perform the C−F activation,
or, participate in a more
active manner, for example, by undergoing insertion of
3 4
2
3 3
21,22
known family of Ru(PPh ) H(halide) complexes to be
isolated.
fluorinated alkenes
or by acting as nucleophiles to displace
3 3
43
fluoride from C−F bonds in hydrodefluorination (HDF)
9
,23−27
reactions.
In the past few years, we have reported that the trans-
dihydride N-heterocyclic carbene (NHC) complexes Ru-
RESULTS AND DISCUSSION
■
Synthesis and Characterization of Ru(IMe ) (PF -
4
2
2
(
NHC) (PPh ) H and Ru(NHC) H2 (NHC = IMe4,
2 3 2 2 4
28
{C F })(C F )H (2). The reaction of a C D solution of 1
6 5 6 5 6 6
IEt Me , IMe ) exhibit the latter type of reactivity in the
2
2
2
29−31
with 5 equiv of PCF resulted in a loss of the Ru−H resonance
catalytic HDF of aromatic fluorocarbons.
In the course of
1
in the H NMR spectrum of 1 (δ −6.54) over the course of ca.
a more general study on the reactivity of the mixed NHC/
2
4 h at room temperature to give one major metal hydride
phosphine complex Ru(IMe ) (PPh ) H (1; Scheme 1), we
4
2
3 2
2
containing product, 2 (the yield of 2 was ca. 70%, as
determined by the integration of all Ru−H signals in the H
NMR spectrum), which appeared as a doublet of triplets signal
at δ −29.63. This was characterized as the unusual five-
coordinate complex 2 (Scheme 1) on the basis of 1D and 2D
NMR experiments using the wealth of spin / nuclei in the
molecule (Figures S1−S7). Thus, the H NMR spectrum
observed that both P(C D ) and P(p-C H Me) readily
6
5 3
6
4
3
1
displaced one or both of the PPh ligands at room
3
3
2,33
temperature.
In contrast, the chelating phosphines Ph P-
2
(
CH ) PPh (dppe), Ph P(CH ) PPh (dppp), and
2
2
2
2
2
3
2
Ph PCH PPh (dppm) could only be substituted into 1 at
2
2
2
1
31
2
elevated temperatures. In an attempt to broaden the scope of
these substitution reactions, we turned our attention to more
electronically diverse phosphines, in particular, the perfluori-
nated phosphine P(C F ) (abbreviated as PCF). While the
1
Received: August 12, 2018
6
5 3
chemistry of PCF (as well as its derivatives) with transition-
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.8b02286
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 1. Bond Activation of PCF with 1
Scheme 2. Substitution Chemistry of 1 with P(C H -p-F) and P(3,4,5-C F H )
2 3
6
4
3
6
3
showed four methyl resonances in a ratio of 6:6:6:6 to 1 for the
PCF. Only signals of low intensity were present in the rest of
the spectrum.
Ru−H signal, confirming the presence of two IMe ligands and
4
a single hydride. The low frequency of the Ru−H resonance
was consistent with the hydride being trans to a vacant
coordination site, while the magnitude of the coupling
Despite exhaustive efforts, 2 could not be crystallized.
Additionally, efforts to crystallize either a chloride derivative
(by dissolution in CH Cl or CHCl ) or a CO/isocyanide-
2
2
3
2
4
constants ( J = 46.1 Hz; J = 6.1 Hz) placed it cis to
trapped derivative also met with failure. It is worth noting that,
HP
HF
3
1
19
both the phosphine- and ruthenium-coordinated C F ligands.
in all of these reactions, P/ F NMR spectra showed that the
PF (C F ) ligand remained intact.
6
5
The extremely unusual difluoro(pentafluorophenyl)phosphine
2
6 5
4
4−46
PF (C F ),
which is, to the best of our knowledge, only
Reactivity of 1 with Other Fluorinated Phosphines.
2
6 5
47
known as a ligand in a single transition-metal complex,
The presence of P(C F ) groups appeared to be mandatory for
6
5
displayed a characteristic high-frequency phosphorus reso-
the bond activation steps described above. Neither P(C H -p-
F) nor P(3,4,5-C F H ) exhibited reactivity comparable to
3 6 3 2 3
6 4
35
nance at δ 161. This appeared as a triplet of multiplets with a
4
8
19
large one-bond triplet JPF splitting of >1100 Hz. The
NMR spectrum revealed a similarly diagnostic high-frequency
δ −31) resonance for the F P unit; this appeared as a doublet
F
that of PCF with 1 (Figures S9 and S10). Thus, the addition of
2 equiv of P(C H -p-F) to a C D solution of 1 resulted in the
6
4
3
6
6
(
slow (3 days) formation of two new triplet hydride resonances
2
2
of triplets with a clearly resolved 1125 Hz doublet splitting to
phosphorus. The 16 Hz triplet splitting was shown by
at slightly lower frequency (δ −6.71 and −6.89, both with J
HP
1
9
F
= 20.6 Hz) from that of 1, which we propose arises from the
COSY NMR to originate from coupling to the two fluorine
substitution of one or two PPh ligands by the fluorinated
3
atoms at the ortho positions of the phosphorus-bound C F
phosphine (Scheme 2). Over a prolonged period (ca. 3 weeks),
further hydride signals appeared between ca. δ −8.3 and −9.1
and ca. δ −11.2 and −11.5. The similarity of these chemical
6
5
1
9
group. The F COSY NMR spectrum allowed the signals for
phosphorus- and ruthenium-bound C6F5 groups to be
differentiated and fully assigned.
32
shifts to those reported previously for isomers of 1 suggests
that the initial mono- and bis-P(C H -p-F) -containing
Given the unexpected structure of 2, 1 was reacted with PCF
under a range of conditions in an attempt to detect any
reaction intermediates. A 1:1 mixture of 1 and PCF resulted in
only incomplete conversion to 2 even after it was allowed to
stand for 3 weeks at room temperature (after this duration, 1
and 2 were present in a 1:0.3 integral ratio; Figure S8). There
were no NMR signals of any intermediates. Heating 1 and PCF
in a 1:1.5 ratio at 50 °C for ca. 24 h brought about the
complete loss of 1 and the formation of 2 in ca. 60% yield by
NMR spectroscopy; again no intermediate species were
observed. Isolation of the reaction volatiles revealed only the
6
4
3
products also undergo isomerization over longer times.
The reaction between 1 and P(3,4,5-C F H ) led to rapid
6
3
2 3
(1 h) and complete conversion to a single new species that
2
exhibited a triplet hydride resonance at δ −6.79 ( J = 20.9
HP
Hz). Over an interval of weeks, this was slowly replaced by a
2
new triplet Ru−H signal at δ −7.13 ( J = 21.1 Hz).
HP
Following from the reactivity of P(C H -p-F) above, these
6
4
3
most likely represent mono- and bis-P(3,4,5-C F H )
6
3
2 3
substitution products. No isomerization was seen in this case
at longer times.
31
presence of C F H. The P NMR spectrum of the reaction
Synthesis and Characterization of Ru(PPh ) HF (3).
6
5
3 3
residue showed signals for 2, free PPh , and some unreacted
The complex series of C−F and P−C bond cleavage steps,
3
B
DOI: 10.1021/acs.inorgchem.8b02286
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Inorganic Chemistry
Article
59
Scheme 3. Synthesis of 3 and Proposed Structures of 4a, 4b, and 5
4
9−53
57
t
58
together with P−F and C−H bond formation,
necessary
Å], Ru(P Bu Me) (CO)(CF )HF [2.065(1) Å], and
Ru(Ind)(SIMes)(P(O Pr) )F [2.017(3)/2.035(4) Å; Ind = 3-
3 2
2
2
2
i
to generate Ru-PF (C F ) and Ru-C F groups and C F H, in
2
6
5
6
5
6
5
tandem with the lack of any observable intermediates, make it
impossible to propose a credible mechanism to account for the
formation of 2. We therefore decided to adopt an alternative
approach, to see if PCF displayed related activation chemistry
with different ruthenium hydride precursors. The treatment of
Ru(PPh ) H with an excess of PCF (4 equiv) led to a change
phenylindenylidene; SIMes = 1,3-bis(2,4,6-trimethylphenyl)-
59
imidazolin-2-ylidene].
In many respects, 3 bears similarity to the recently reported
51d,e
rhodium fluoride complex Rh(PPh ) F,
in that they each
3
3
represent the last member of the well-known families of
Ru(PPh ) H(halide) and Rh(PPh ) (halide) complexes to be
3
4
2
3 3
3 3
from a yellow suspension to a homogeneous red solution over
ca. 2 h at room temperature. 31P NMR spectroscopy revealed
the presence of unreacted PCF and complete loss of ruthenium
starting material but no obvious new product resonances.
prepared. The solution fluxionality of Ru(PPh ) HX (X = Cl,
3 3
43,60
Br, I)
was apparent in 3. Because the complex showed
reasonable solubility across a range of solvents, variable-
1
31
19
temperature H, P, and F NMR spectra were recorded in
dichloromethane, THF, and toluene. Figure 2 shows
representative examples of spectra; complete sets of spectra
1
However, the low-frequency region of the H NMR spectrum
did show the formation of a quartet resonance at δ −22.33,
attributable to 3 (Scheme 3). The identity of 3, which was
isolated in ca. 80% yield as an air-sensitive red-orange solid,
was established unequivocally by X-ray diffraction, as shown in
in all solvents are provided in Figures S11−S17. At 298 K, the
2
hydride resonance in 3 appeared as a quartet with J = 28.0
HP
Hz in CD Cl , THF-d , and C D CD (Figure 2a,b). This
2
2
8
6
5
3
Figure 1. The P −Ru−P angle of 153.023(17)° is similar to
ax
ax
became a broad multiplet in CD Cl at 199 K, whereas a more
2 2
coupled multiplet was observed in both toluene and THF at
the same temperature. The best resolved low-temperature
spectrum was measured in C D CD at 199 K (Figure 2c); this
6
5
3
2
31
simplified to a doublet with a J splitting of 16.0 Hz with P
HF
decoupling (Figure 2d). While we were unable to observe any
3
3
1
1
P resonance in any solvent at room temperature, the 199 K
1
P{ H} NMR spectrum recorded in C D CD consisted of a
6
2
5
3
2
1
:2 ratio of a doublet of triplets (δ 91; J = 84 Hz; J = 23
PF PP
Hz) and a broadened triplet (δ 41; J ≈ 21 Hz; see the
Supporting Information). In all solvents across the temperature
range 298−199 K, the Ru−F resonance only ever appeared as a
broad singlet, ranging in chemical shift from δ −190 to −205
61
(
Figure 2e).
Mechanism of Formation of 3. In contrast to the
complex bond activation/formation steps involved in the
formation of 2, the formation of 3 arises by HDF of PCF. This
was probed by monitoring the reaction of different ratios of
Ru(PPh ) H /PCF by NMR spectroscopy. With substoichio-
Figure 1. Molecular structure of 3. Ellipsoids are shown at 30%
probability. Hydrogen atoms, with the exception of the Ru−H ligand,
are omitted for clarity. Selected bond lengths (Å) and angles (deg):
Ru1−F1 2.0652(12), Ru1−P1 2.3423(4), Ru1−P2 2.1996(5), Ru1−
P3 2.3201(5); P1−Ru1−F1 88.19(4), P2−Ru1−F1 133.51(5), P1−
Ru1−P3 153.023(17).
3
4
2
metric ratios of Ru/PCF (i.e., 6:1 and 9:1), we were able to
observe three minor ruthenium-containing products (4a, 4b,
and 5) in addition to 3 (Scheme 3 and Figure S19). Each of
1
9
these species showed two F NMR signals (a doublet of
doublets and a triplet of triplets, relative ratio of 2:1) at much
higher frequency than the fluoride resonance of 3, in a region
of the spectrum associated with fluoroaromatic groups. A
54,55
that found in the chloride, bromide, and iodide derivatives.
In contrast, the P −Ru−X angle ranged from a value of
subsequent reaction of Ru(PPh ) H with P(3,4,5-C F H )
3 4 2 6 3 2 3
62
eq
55
1
33.41(5)° in 3 to 116.428(13)° in Ru(PPh ) HBr. The
afforded the same three species, but no 3 (Figure S20). All
four ruthenium species (3, 4a, 4b, and 5) can be rationalized
by ortho-HDF of PCF. The regioselectivity is consistent with a
pathway involving the substitution of PCF into Ru(PPh ) H ,
3
3
Ru−F bond length [2.0652(12) Å] was comparable to the
values found in a range of other five- and six-coordinate
ruthenium(II) fluoride complexes, such as cis-Ru(dppp) F
2
2
3 4
2
5
6
[
2.056(3)/2.069(3) Å], Ru(PPh ) (CO)HF [2.0986(15)
followed by intramolecular nucleophilic attack by Ru−H at an
3
3
C
DOI: 10.1021/acs.inorgchem.8b02286
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Inorganic Chemistry
Article
1
Figure 2. H NMR spectrum (400 MHz) of the Ru−H resonance of 3 in (a) CD Cl (298 K), (b) THF-d (298 K), and (c) C D CD (199 K).
2
2
8
6
5
3
1
31
19
(
d) H{ P} NMR spectrum in C D CD at 199 K. (e) F NMR spectrum (376 MHz) of the Ru−F resonance of 3 in THF-d at 298 K.
6
5
3
8
Scheme 4. Possible Pathway for the Intramolecular HDF of PCF To Form 3
o-C−F position. An analogous intramolecular attack of a Pt-
to be placed very readily in close proximity to the reactive Pt-
OMe group.
OMe ligand has been proposed to account for the reaction of
+
Scheme 4 shows a possible pathway to 3. The initial
intramolecular HDF at an o-C−F bond would yield the
substituted hydride fluoride complex I (assumed to be five-
coordinate like 3), which could then bring about a second
the o-C−F bonds in [Pt(PPh C F ) (THF)Me] with NaOMe
2
6 5 2
3
9,40
to give Pt(PPh {2,6-(OMe) C F }) (OMe)Me.
Very
2
2
6
3
2
6
3
recently, Kayaki and co-workers have reported that Ir−H
complexes bearing fluorinated phenylsulfonyl-1,2-diphenyle-
thylenediamine ligands undergo HDF at the o-C−F position to
generate iridacycle products.
64,65
HDF step with formation of the difluoride complex II.
Comproportionation of II and Ru(PPh ) H (known for
3
4
2
55
[
Ru(PPh ) I ] and Ru(PPh ) H ) would then generate a
3 2 2 2 3 4 2
Formation of the P(3,4,5-C F H ) complexes 4a/4b and 5,
6
3
2 3
reactive Ru−H ligand in III, allowing HDF to propagate until
P(3,4,5-C F H ) is formed.
together with the lack of any signals for bound or free partially
6
3
2 3
hydrodefluorinated phosphines [e.g., P(3,4,5-C F H )-
6
3
2
Reactivity of 3. Like for other Ru(PPh ) HX complexes, 3
3
3
(
C F ) ], implies that HDF of all six available o-C−F sites in
6
5 2
was stable in solution under inert conditions but degraded
rapidly upon exposure to air to afford green-black solutions. It
proved to be relatively thermally robust in solution, with traces
a molecule of PCF must be rapid and certainly faster than the
dissociation of any partially hydrodefluorinated phosphine. In
the platinum chemistry above, Roundhill suggested that facile
1
of new signals only apparent by H NMR spectroscopy upon
free rotation about the Pt−PR bond allows all four o-fluorines
heating at 70 °C in THF-d for ca. 7 h. Dissolution of 3 in
3
8
D
DOI: 10.1021/acs.inorgchem.8b02286
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Inorganic Chemistry
Article
Scheme 5. Reactivity of 3
CD Cl afforded traces of Ru(PPh ) HCl within hours,
the products from reaction with B pin . The initial formation
2
2
3
3
2
2
although complete conversion required days at room temper-
ature (Figure S23). Ru(PPh ) HBr was formed in time of
of 8 releases FBpin, which could be trapped by 3 to give 7.
When the reaction was monitored quantitatively in the
presence of an internal standard, all of the ruthenium was
accounted for by the concentrations of 7 and Ru(PPh ) H .
3
3
mixing upon the addition of C H CH Br to 3, whereas
6
5
2
reaction with bromodecane only occurred over several days.
No reaction took place with PhI either at room temperature or
at 70 °C.
3
4
2
However, mass balance of the Ru−H ligands requires some
additional source of hydride. The presence of adventitious
The treatment of 3 with NaBArF in CH Cl (Scheme 5)
moisture (in solvent, on glassware, or in the sample of B pin )
4
2
2
2 2
resulted in an almost near-instantaneous disappearance of the
most likely accounts for this and also helps to rationalize
F
4
71
starting material and formation of the [BAr ] salt 6 of the
degradation of the boryl ligand in 8. There were only minor
6
+
known cation [Ru(η -C H PPh )(PPh ) H] , which was
differences in the reaction profile upon changes in the
stoichiometry of the reaction. Thus, with just 0.5 equiv of
6
5
2
3 2
identified through the presence of a triplet of doublets Ru−
31
H hydride resonance at δ −8.61 and two P signals at δ 49.0
B
2
pin
consumed, the formation of 7, Ru(PPh
observed at early times in the reaction, and 8 ultimately
2
, although 3 (unsurprisingly) took longer to be
6
6,67
and −5.2 (Figure S24).
) H
3 4 2
, and 8 was still
1
Reactivity of 3 with B pin and HBpin. A H NMR
2
2
72
spectrum of a C D solution of 3 recorded 5 min after the
disappeared to leave just 7 and Ru(PPh
The reaction of 3 with an equimolar amount of HBpin in
toluene-d gave the toluene analogue of 7 and Ru(PPh ) H ,
3 4 2
) H .
3 4 2
6
6
addition of 1 equiv of B pin showed residual starting material
2
2
in an integral ratio of 1:0.2:0.4 to two new Ru−H-containing
products 7 and 8 with resonances at δ −5.50 and −9.33,
respectively (Scheme 5 and Figures S25−S27). The chemical
shift and coupling constant of 7 are consistent with those of
8
but in this instance, they were accompanied by the formation
2
of both the dihydrogen dihydride complex Ru(PPh ) (η -
3 3
73,74
H )H
and free FBpin (Scheme 7 and Figures S28 and
S29). The composition of the reaction mixture changed over 2
2
2
6
+
2
the cation [(η -arene)Ru(PPh ) H] (δ −9.33; t, J = 36.7
3
2
HP
6
8
2
days to ultimately afford only Ru(PPh ) H and Ru(PPh ) (η -
Hz), in which the arene is presumably C D . The presence of
a broad B{ H} NMR triplet resonance ( J = ca. 19 Hz) at δ
3 4
2
3 3
6
6
1
1
1
1
H )H . However, when an excess of HBpin (5 equiv) was
2
2
BF
19
employed, quite different chemistry was observed (Scheme 7)
with formation of the σ-borane dihydride complex Ru-
6
.7, along with a broad F resonance at ca. δ −141, indicates
−
69
that [F Bpin] is the accompanying anion.
2
(
PPh ) (σ-HBpin)H (9), along with a minor species
Within 30 min, an additional second-order hydride signal for
3 3 2
1
discussed further below (Figures S30−S32). Crystals of 9
suitable for X-ray diffraction (Figure 3) were obtained upon
Ru(PPh ) H appeared in the H NMR spectrum at δ −10.16.
3
4
2
This increased in intensity over time at the expense of 8. After
layering of a C H solution of the complex containing 10 equiv
1
h, 3 had been fully consumed, and after ca. 2 h, 8 was also no
6
6
of HBpin with pentane.
longer present.
The analysis of key structural metrics in comparison to those
We propose that 8 is the hydride boryl complex
2
70
of Ru(PCy ) (η -H )(σ-HBPin)H support the formulation as
Ru(PPh ) H(Bpin). Scheme 6 shows a possible pathway to
3 2
2
2
3
3
75−77
a σ-borane dihydride rather than hydroborate species.
Thus, there is a small, but significant difference between the
B1−H2 [1.36(2) Å] and B1−H1 [1.57(2) Å] distances,
consistent with assignment of the former to σ-B−H and the
latter to Ru−H···B. The orientation of the Bpin group (i.e., the
Scheme 6. Possible Mechanism for the Reaction of 3 and
B2pin2
[
O,O]−B−Ru angle) has been promoted by Sabo-Etienne and
co-workers as being particularly diagnostic of the B−H
76
2
coordination mode. Thus, in Ru(PCy ) (η -H )(σ-HBPin)-
3
2
2
H , this angle is 170.0°, while the mixed σ-borane/
2
2
dihydroborate species Ru(PCy ) (σ-HBPin)(η -H Bpin)H
3
2
2
has a corresponding angle of 171.5° for the borane and
E
DOI: 10.1021/acs.inorgchem.8b02286
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 7. Reactions of 3 with HBpin as a Function of the Stoichiometry
parentheses measured at 211 K), 500 MHz] support these
1
1
assignments. The B NMR spectrum showed just a single
broad resonance at δ 21.9; in contrast to complexes described
by Sabo-Etienne and co-workers, this signal is on the lower-
7
6
frequency side of that for free HBpin.
1
H NMR spectra of redissolved crystalline 9 showed the
same minor product noted above that is observed in the initial
reaction of Ru(PPh ) H with HBpin. This species displayed a
3
4
2
multiplet Ru−H resonance at δ −9.49 [T = 195 (259 K) and
1
79
31
4
40 (211 K) ms at 500 MHz] that correlated to a sharp P
singlet at δ 46. The identity of this complex remains unclear.
Moreover, unless free HBpin was present in solution, the
2
formation of Ru(PPh ) (η -H )H was also observed spec-
3
3
2
2
troscopically (Figure S33). After 3 weeks in solution, the
dihydrogen dihydride complex was the only remaining
1
ruthenium species observable by H NMR spectroscopy.
A preliminary investigation suggested that 3 reacted with
catecholborane (5 equiv) in the same way as for HBpin,
1
although less cleanly. The room temperature H NMR
spectrum featured a number of broad low-frequency
resonances, which upon cooling to 235 K sharpened to reveal
an obvious 1:1:1 set of signals at ca. δ −4.7, −7.9, and −10.0
assignable to Ru(PPh ) (σ-HBcat)H . However, there were
also quite a significant number of other low-frequency signals;
therefore, the reaction was not pursued further.
Figure 3. Molecular structure of 9. Thermal ellipsoids are shown at
0% probability. Hydrogen atoms, with the exception those attached
to ruthenium and boron are omitted for clarity. Selected bond lengths
3
3
3
2
(
Å) and angles (deg): Ru1−B1 2.1747(16), Ru1−P1 2.3337(4),
Ru1−P2 2.3885(4), Ru1−P3 2.3398(4); P1−Ru1−P2 99.278(13),
P1−Ru1−P3 152.859(13), P2−Ru1−P3 97.146(13).
Reactivity of 3 with Silicon Reagents. 3 reacted rapidly
with Me SiCF (1 or 10 equiv, toluene or THF, in the absence
3
3
and presence of CsF) to bring about complete disappearance
of the ruthenium complex in less than 24 h. The presence of
1
77.5° for the dihydroborate; in 9, the value is 170.05(16)°.
The Ru−B distance of 2.1747(16) Å in 9 is also similar to that
in Ru(PCy ) (η -H )(σ-HBPin)H [2.173(2) Å].
2
Me SiF, PPh , and CF H (Figures S34 and S35), together with
3
3
3
3
2
2
2
1
the absence of any new ruthenium-containing species,
Redissolved crystals of 9 gave a H NMR spectrum
comprised of three broad low-frequency signals at δ −5.95,
suggested that conversion of 3 to Ru(PPh ) H(CF ) may
3 3
3
80
−
8.03, and −10.52 in a 1:1:1 ratio at 298 K. At 259 K, the two
have taken place but was followed by facile decomposition.
This is consistent with the paucity of Ru-CF complexes in the
lowest-frequency resonances resolved into a triplet of doublets
3
8
1
2
2
(
J = 27.4 and 16.6 Hz) and a doublet of triplets ( J = 58.7
literature. Indeed, all of the examples that are known contain
a π-accepting CO ligand and display a strong susceptibility to
undergo α-fluorine elimination to yield difluorocarbene
HP
HP
and 17.6 Hz), respectively. The signal at ca. δ −6 remained as a
singlet, albeit much sharper. Additional low-temperature NMR
measurements showed that all three resonances (i) were
unchanged in the 211 K H{ B} NMR spectrum but collapsed
to singlets in the H{ P} NMR spectrum at the same
temperature, (ii) were all in exchange (EXSY, 259 K; Figure
S32), and (iii) correlated ( H− P HMQC, 211 K) to a
doublet (δ 52.2, J = 25 Hz) and a triplet (δ 50.5, J = 25
Hz) in the P{ H} NMR spectrum. The multiplicities of the
proton resonances at low temperature, together with the
5
8,82−84
complexes.
The reaction of 3 with Me SiC F (again
3 6 5
1
11
over a range of solvents, in different stoichiometries, and in the
absence/presence of CsF) was much slower than that with
1
31
Me
containing products. Free C
apparent as a result of decomposition (Scheme 8).
The addition of 2 equiv of R SiH (R = Et, Ph) to C D
6
SiCF
3
but again failed to generate any new Ru-C
F -
3
6 5
1
31
F
6
H and Ru(PPh were
) H
3 4 2
5
2
2
PP
PP
7
8
31
1
3
6
solutions of 3 generated Ru(PPh ) (SiR )H [R = Et (10), Ph
3
3
3
3
magnitudes of J , allow clear assignment of the signals at
(11); Scheme 8] in the time of mixing (Figures S36−S39).
Both complexes were initially reported over 40 years ago
following the reaction of Ru(PPh ) H with the appropriate
HP
room temperature at ca. δ −6, −8, and −10.5 to σ-B−H, Ru−
H, and Ru−H···B, respectively. The respective T values of 163
1
3 4
2
85,86
1
(
378), 291 (865), and 191 (447) ms [259 K (values in
silane,
although their characterization was limited to H
F
DOI: 10.1021/acs.inorgchem.8b02286
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 8. Reactions of 3 with Silicon Reagents
SUMMARY AND CONCLUSIONS
■
Two very different products, 2 and 3, result from the reactions
of the ruthenium dihydride complexes 1 and Ru(PPh ) H
3
4
2
with PCF. The complexity of the C−F/P−C bond cleavage
and P−F bond formation steps involved in the formation of 2,
together with the lack of observable intermediates on the
reaction pathway, provides no obvious clues to the mechanism
of the reaction, although it seems likely that the high
nucleophilicity of the hydride ligands in 1 that results from
the trans H−Ru−H geometry is an important feature of the
NMR/IR spectroscopy and elemental analysis. X-ray-quality
crystals of 10 were isolated upon the slow evaporation of a
THF solution of the complex, while those of the SiPh3
analogue were isolated from benzene/hexane following the
generation of 11 by the reaction of Ru(PPh ) H and Ph SiH.
overall process. The use of varying ratios of Ru(PPh ) H and
3 4
2
PCF, as well as the use of the partially fluorinated phosphine
P(3,4,5-C F H ) , provides good evidence that 3 is formed via
6
3
2 3
an intramolecular attack of the Ru−H ligands to bring about
HDF of the o-C−F positions of a coordinated PCF ligand. 3
shows features of the well-known heavier halide analogues,
particularly the highly fluxional behavior in solution. In terms
of reactivity, the fluoride ligand in 3 is readily displaced by
boranes and silanes. A total of 50 years after Wilkinson’s
3
4
2
3
The hydride ligands were located and refined without
restraints in the molecular structure of 10, whereas in 11,
they were located and refined, subject to being equidistant
from Ru1 (Figure 4). As noted for other group 8 metal
8
7−92
ML (SiR )H complexes,
there is an approximately
43
3
3
3
seminal report of Ru(PPh ) HCl, we are delighted to have
3
3
tetrahedral arrangement of the SiP units with the hydride
3
completed the family of known Ru(PPh ) H(halide) com-
3
3
ligands capping the SiP faces.
2
plexes, albeit via an unanticipated reaction.
Differentiating between silane and silyl hydride coordination
modes remains the focus of much debate and discus-
EXPERIMENTAL SECTION
7
7,93−95
■
sion.
The shortest Si···H contact in 10 involves H1C,
General Considerations. All manipulations were carried out
using standard Schlenk, high-vacuum, and glovebox techniques using
dry and degassed solvents. C D , C D CD , and THF-d were
and at 2.02(2) Å, it is comparable to the values noted in
9
6
R u ( P M e ) ( S i M e ) H
( 2 . 1 3 Å ) ,
R u -
and Ru-
IMe ) (PPh )(SiPh )H (2.075 Å). This suggests that 10
3
3
3
3
9
7
6
6
6
5
3
8
(
(
PMe ) (SiMe CH SiMe )H (2.00 Å)
3 3 2 2 3 3
vacuum-transferred from potassium, while CD Cl was distilled from
2
2
31
4
2
3
3
3
CaH . NMR spectra were recorded at 298 K (unless otherwise stated)
2
is best considered to be a silyl trihydride complex, which
on Bruker Avance 400 and 500 MHz NMR spectrometers and
1
13
1
retains some degree of interaction between the silicon and
referenced as follows: C
6
D
6
( H, δ 7.15; C, δ 128.0), C
6
D
5
CD
3
( H,
1
3
1
1
2
δ 2.09; C, δ 21.3), THF-d ( H, δ 3.58), and CD Cl ( H, δ 5.32).
Hhydride centers. In line with this, the J splitting (23 Hz) lies
8
2
2
SiH
3
1
1
P{ H} NMR spectra were referenced externally to 85% H PO (δ
3
4
between 10 and 65 Hz, values proposed as representing the
1
9
0
.0) and F NMR spectra externally to CFCl3 (δ 0.0). PPh3
upper limit for M(Si)H and the lower limit for M(σ-Si−H)
resonances are excluded unless they could be assigned unequivocally.
Elemental analyses were performed by Elemental Microanalysis Ltd.,
77
species, respectively. The T value of 300 ms (258 K, 400
1
3
2
MHz) for the hydride resonance in 10 rules out any
Okehampton, Devon, U.K. Ru(IMe ) (PPh ) H (1) and Ru-
4
2
3
2
2
92
98
nonclassical dihydrogen interactions.
(PPh ) H were prepared according to literature methods.
3 4 2
Figure 4. Molecular structures of 10 (left) and 11 (right). Ellipsoids are shown at 30% probability. Hydrogen atoms (with the exception of those
bound to ruthenium, as well as the disordered component of one phenyl ring attached to Si1 in 11) have been omitted for clarity. Selected bond
lengths (Å) and angles (deg) for 10: Ru1−Si1 2.4114(5), Ru1−P1 2.3969(4), Ru1−P2 2.4333(5), Ru1−P3 2.4043(4); P1−Ru1−P2 105.604(16),
P1−Ru1−P3 102.854(15), P1−Ru1−Si1 112.757(17). Selected bond lengths (Å) and angles (deg) for 11: Ru1−Si1 2.3682(16), Ru1−P2
2.4288(5), Ru1−P3 2.4332(6), Ru1−P4 2.4404(5); P2−Ru1−P3 104.980(18), P2−Ru1−P4 104.597(17), P2−Ru1−Si1 114.49(2).
G
DOI: 10.1021/acs.inorgchem.8b02286
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
1
9
Ru(IMe ) (PF {C F })(C F )H (2). 1 (17 mg, 0.019 mmol) and
Hz)] and Me SiF [ F NMR (C D CD , 470 MHz) δ −157.9 (m);
4
2
2
6
5
6
5
3
6
5
3
1
9
PCF (21 mg, 0.039 mmol) were combined with C H (0.5 mL) in a J.
F NMR (THF-d ) δ −158.2 (m)].
6
6
8
Young’s resealable NMR tube, and the solution was heated at 50 °C
Ru(PPh ) (SiEt )H (10). 3 (34 mg, 0.038 mmol) and Et SiH (12
3 3 3 3 3
for 24 h. The deep-red solution was analyzed by NMR spectroscopy
μL, 0.076 mmol) were shaken vigorously in THF-d in a J. Young’s
resealable NMR tube for 2 h to give a pale-orange solution. Pale-
yellow crystals of 10 were obtained upon the slow evaporation of
solvent. These were washed with pentane (3 × 0.5 mL) and dried in
8
1
and shown to contain 2 as the major product. H NMR (C D , 500
6
6
MHz): δ 3.38 (s, 6H, NCH ), 3.27 (s, 6H, NCH ), 1.31 (s, 6H,
3
3
2
4
NCCH ), 1.24 (s, 6H, NCCH ), −29.63 (dt, J = 46.1 Hz, J
.1 Hz, 1H, RuH). P{ H} NMR (C D , 202 MHz): δ 161.5 (tm,
=
3
3
HP
HF
3
1
1
6
1
6
6
vacuo. Yield: 13 mg (34%). H NMR (THF-d , 400 MHz): δ 7.19−
8
1
19
1
JPF = 1126 Hz). F NMR (C D , 470 MHz): δ −31.1 (dt, J
=
3
6
6
FP
7.08 (m, 27H, PC H ), 6.99−6.89 (m, 18H, PC H ), 0.61 (t, J
=
HH
6
5
6
5
4
3
1
−
1
125 Hz, J = 16 Hz, 2F, PF ), −114.5 (br m, 2F, Ru-o-C F ),
FF
2
6
5
7.4 Hz, 9H, SiCH CH ), 0.43 (q, J = 7.4 Hz, 6H, SiCH CH ),
2 3 HH 2 3
3
1
31
2
137.3 (m, 2F, P-o-C F ), −154.4 (t, J = 21 Hz, 1F, P-p-C F ),
6
5
FF
6
5
−10.58 [m, 3H, RuH ; H{ P} NMR: s, J = 22.3 Hz; T = 300 ms
31 1
3
SiH
1
3
62.7 (m, 2F, P-m-C F ), −163.1 (t, JFF = 20 Hz, Ru-p-C F ),
6
5
6
5
(258 K, 400 MHz)]. P{ H} NMR (THF-d , 162 MHz): δ 41.8 (s).
8
1
3
1
−
163.4 (m, 2F, Ru-m-C F ). Selected C{ H} NMR (125 MHz,
29
1
6
5
Si− H HMBC NMR (THF-d , 258 K): δ 3.3 (br s). Anal. Calcd
8
C D ; signals from the C F groups were not assigned): δ 188.3 (d,
6
6
6
5
(found) for C H P SiRu: C, 71.61 (71.32); H, 6.31 (6.66).
60 63 3
2
JCP = 17 Hz, NCN), 124.3 (s, NCCH ), 124.0 (s, NCCH ), 34.5 (s,
3
3
Ru(PPh ) (SiPh )H (11). (a) Ph SiH (2 mg, 0.008 mmol) was
3 3 3 3 3
added to a C D solution of 3 (4 mg, 0.004 mmol) in a J. Young’s
resealable NMR tube. H and P NMR spectroscopy showed
complete conversion to 11 within 40 min. (b) 11 was generated on a
preparative scale by the slow addition of a C H (2 mL) solution of
Ph SiH (34 mg, 0.13 mmol) to a benzene (5 mL) solution of
Ru(PPh ) H (100 mg, 0.087 mmol). The reaction mixture was left to
stand overnight, after which time the color had changed from pale
yellow to colorless. The solution was layered with hexane, which
slowly precipitated at colorless crystals of 11 at room temperature (40
NCH ), 33.4 (s, NCH ), 8.7 (s, (s, NCCH ), 8.0 (s, NCCH ).
3
3
3
3
6 6
Ru(PPh ) HF (3). Ru(PPh ) H (300 mg, 0.26 mmol) and PCF
1
31
3
3
3
4
2
(
48 mg, 91.1 μmol) were dissolved in C H (2 mL) and stirred at 298
6 6
K overnight to afford a deep-red solution. This was filtered by cannula
6
6
and the filtrate layered with pentane to afford 3 as dark-red crystals.
1
3
Yield: 203 mg (79%). H NMR (THF-d , 500 MHz): δ 7.27 (t, JHP=
8
3
4
2
7
=
.8 Hz, 18H, PC H ), 7.12 (t, J = 7.4 Hz, 9H, PC H ), 6.94 (t, J
6
5
HP
6
5
HP
19
2
7.6 Hz, 18H, PC H ), −22.33 (q, J = 28.0 Hz, 1H, RuH).
F
6
5
HP
NMR (THF-d , 376 MHz): δ −208.1 Anal. Calcd (found) for
8
C H P Ru: C, 71.42 (71.80); H, 5.11 (5.24).
1
5
4
46 3
mg, 80% yield). Selected H NMR (C D , 500 MHz): δ −9.37 (m,
F
6
6
Reaction of 3 with NaBAr . 3 (14 mg, 0.015 mmol) was
31
1
4
3
H, RuH ). P{ H} NMR (C D , 202 MHz): δ 37.5 (s). Anal. Calcd
combined with excess NaBArF (34 mg, 0.038 mmol) in CD Cl in a
3 6 6
4
2
2
(
found) for C H P SiRu: C, 75.17 (75.16); H, 5.52 (5.82).
1
31
1
72 63 3
J. Young’s resealable NMR tube. The H and P{ H} NMR spectra
X-ray Crystallography. Data for compounds 3, 9, 10, and 11
6
recorded after ca. 30 min showed the formation of [Ru(η -
F
1
were obtained using an Agilent SuperNova instrument and a Cu Kα
source. These crystallographic experiments were conducted at 150 K,
with the exception of that for 10 (for which data were garnered at 200
K). All structures were solved using Olex2 and refined using
SHELXL. Refinements were uneventful in the main feature. The
C H PPh )(PPh ) H][BAr ] (6). Diagnostic H NMR (400 MHz,
6
5
2
3
2
4
3
3
CD Cl ): δ 6.64 (t, J = 5.9 Hz, 1H, C H PPh ), 5.08 (t, J = 5.7
Hz, 2H, C H PPh ), 4.41 (m, 2H, C H PPh ), −8.61 (td, J = 38.6
Hz, J = 8.6 Hz, 1H, RuH). P{ H} NMR (CD Cl , 162 MHz): δ.
2
2
HH
6
5
2
HH
2
6
5
2
6
5
2
HP
99
3
31
1
HP
2
2
100
4
9.0 (s), −5.2 (s).
only additional points of note include the fact that the asymmetric
units in 3 and 9 each housed one molecule of the ruthenium complex
and one guest molecule of benzene. The hydride ligands were located
in both cases, while H1 in 3 was refined at a distance of 1.6 Å from
Ru1; those in 9 were refined without restraints. In 10, the asymmetric
unit was seen to contain one molecule of the complex and two
molecules of THF. The hydrides in the main feature were readily
located and refined without restraints. One of the solvent molecules
was treated with the Olex2 solvent mask algorithm because it is
heavily disordered. The second solvent entity exhibited disorder of
O1 and C6 therein in a 50:50 ratio. The assignment of the oxygen is
somewhat tentative because, ultimately, fractional occupancy atoms
O1 and O1a were restrained to having similar anisotropic displace-
ment parameters (ADPs) in the final least squares to assist
convergence. The asymmetric unit in 11 was seen to comprise one
molecule of the complex and three regions of solvent, which
amounted to 2.5 molecules of benzene. The hydride ligands in the
main feature were located and refined, subject to being equidistant
from Ru1. The phenyl ring based on C13 (attached to Si1) was seen
to be disordered in equal proportions over two proximate sites and
the associated Si−C13/C13A distances were restrained to being
similar in the final least squares. Two of the solvent regions required
disordered modeling. In particular, the one total benzene moiety
based on C72 was modeled for disorder over two regions in a 50:50
ratio, while that based on C82 was disordered over three overlapped
regions in a 40:40:20 ratio. The arising five fractional occupancy rings
in these two regions were refined as rigid hexagons, and ADP
restraints were also included to assist convergence. The half-molecule
of benzene present at half-occupancy (C88−C90) is located
proximate to an inversion center, which serves to generate the
remainder of that entity.
Reaction of 3 with B pin . C D solutions of 3 (15 mg, 0.017
2
2
6
6
mmol) and B pin (4 mg, 0.016 mmol) or 3 (16 mg, 0.018 mmol)
2
2
and B pin (2 mg, 0.008 mmol) were prepared in J. Young’s NMR
2
2
tubes and the reactions monitored by NMR spectroscopy. Spectra
6
1
indicated the formation of [(η -C D )Ru(PPh ) H][F Bpin] [7; H
6
6
3
2
2
2
NMR (C D , 500 MHz) δ −9.33 (t, J = 36.7 Hz, 1H, RuH);
6
6
HP
3
1
1
11
1
P{ H} NMR (C D , 202 MHz, 298 K) δ 51.8 (s); B{ H} NMR
6
6
1
19
(
C D , 160 MHz) δ 6.7 (br t, J = 19 Hz); F NMR (C D , 470
6 6 BF 6 6
1
MHz) δ −141 (br s, Ru(PPh ) H ); H NMR (C D , 500 MHz) δ
10.16 (m, 2H, RuH); P{ H} NMR (C D , 202 MHz) δ 49.3 (t,
JPP = 14 Hz), 41.1 (t, J = 14 Hz)] and 8, which is tentatively
3
4
2
6
6
3
1
1
−
6 6
2
2
PP
1
assigned as Ru(PPh ) H(Bpin) [ H NMR (C D , 500 MHz) δ −5.50
3
3
6
6
2
2
31
1
(
dt, J = 59.9 Hz, J = 31.6 Hz, 1H, RuH); P{ H} NMR (C D ,
HP HP 6 6
2
02 MHz) δ 55.3 (d, JPP = 15 Hz), 43.7 (t, JPP = 15 Hz)].
Ru(PPh ) (HBpin)H (9). A C H solution (0.5 mL) of 3 (15 mg,
3
3
2
6
6
16.5 μmol) and HBPin (24.0 μL, 0.16 mmol) was layered with
pentane to afford a small amount of crystals of 9 over a period of ca. 2
1
weeks. Selected H NMR (C D CD , 400 MHz, 259 K): δ 0.77 (s,
6
5
3
2
2
1
1
2H, Bpin), −5.95 (br s, 1H, BH), −8.04 (td, J = 27.8 Hz, J
=
HP
HP
2
2
6.5 Hz, 1H, RuH), −10.46 (dt, J = 59.6, J = 17.5 Hz, 1H,
HP
HP
31
1
RuH···B). P{ H} NMR (C D CD , 162 MHz, 259 K): δ 52.2 (d,
6
5
3
2
2
11
JPP = 25 Hz), 50.4 (t, J = 25 Hz). B NMR (C D CD , 128 MHz,
PP
6
5
3
2
59 K): δ 21.9 (br s). Consistently high % C values prevented
satisfactory elemental analysis for 9 from being determined [e.g., anal.
calcd (found) for C H BO P Ru: C, 70.85 (71.50); H, 5.85 (5.75)].
6
0
59
2 3
Reaction of 3 with Me SiCF . Reactions were conducted at
3
3
room temperature in J. Young’s resealable NMR tubes using (i) 3 (6.6
mg, 0.007 mmol) and Me SiCF (10.7 μL, 0.015 mmol) in C D CD
3
3
6
5
3
or THF-d or (ii) 3 (23 mg, 0.025 mmol) and Me SiCF (7.6 μL,
8
3
3
0
.051 mmol) in C D CD or THF-d , both in the absence and
6 5 3 8
1
19
presence of CsF (2.3 mg, 0.015 mmol). In all cases, H and F NMR
spectroscopy showed the formation of CF H [ H NMR (C D CD ,
1
Crystallographic data for all compounds have been deposited with
the Cambridge Crystallographic Data Centre as supplementary
publications CCDC 1849162−1849165 for 3, 9, 10, and 11,
respectively.
3
6
5
3
2
19
5
00 MHz) δ 7.23 (q, J = 80.0 Hz); F NMR (C D CD , 470
HF 6 5 3
2
1
MHz) δ −79.2 (d, J = 79.8 Hz); H NMR (THF-d , 500 MHz) δ
6
FH
8
2
19
2
.89 (q, J = 79.6 Hz); F NMR (THF-d ) δ −79.5 (d, J = 79.6
HF
8
FH
H
DOI: 10.1021/acs.inorgchem.8b02286
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
(
11) Eisenstein, O.; Milani, J.; Perutz, R. N. Selectivity of C−H
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.8b02286.
■
Activation and Competition between C−H and C−F Bond Activation
at Fluorocarbons. Chem. Rev. 2017, 117, 8710−8753.
*
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(12) Aizenberg, M.; Milstein, D. Homogeneous Rhodium Complex-
Catalyzed Hydrogenolysis of C-F Bonds. J. Am. Chem. Soc. 1995, 117,
8674−8675.
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Multinuclear NMR spectra for complexes 2−11 (PDF)
Complexes: Synthesis, Dynamics and Reactivity of Platinium Hydride
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Bifluoride Complexes. J. Am. Chem. Soc. 2000, 122, 8685−8693.
(
14) Braun, T.; Noveski, D.; Neumann, B.; Stammler, H. G.
CCDC 1849162−1849165 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
Conversion of Hexafluoropropene into 1,1,1-Trifluoropropane by
Rhodium-Mediated C−F Activation. Angew. Chem., Int. Ed. 2002, 41,
2
(
745−2748.
15) Kraft, B. M.; Jones, W. D. Carbon−Fluorine Bond Activation of
Perfluorinated Arenes with Cp* ZrH . J. Organomet. Chem. 2002,
2
2
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16) Barrio, P.; Castarlenas, R.; Esteruelas, M. A.; Lledos
Maseras, F.; Onate, E.; Tomas, J. Reactions of a Hexahydride-
́
, A.;
AUTHOR INFORMATION
Corresponding Author
E-mail: M.K.Whittlesey@bath.ac.uk.
̃
̀
■
Osmium Complex with Aromatic Ketones: C−H Activation Versus
C−F Activation. Organometallics 2001, 20, 442−452.
(
*
17) Noveski, D.; Braun, T.; Schulte, M.; Neumann, B.; Stammler,
ORCID
H. G. C−F Activation and Hydrodefluorination of Fluorinated
Michael K. Whittlesey: 0000-0002-5082-3203
Notes
The authors declare no competing financial interest.
Alkenes at Rhodium. Dalton Trans. 2003, 4075−4083.
(18) Schwartsburd, L.; Mahon, M. F.; Poulten, R. C.; Warren, M. R.;
Whittlesey, M. K. Mechanistic Studies of the Rhodium NHC
Catalyzed Hydrodefluorination of Polyfluorotoluenes. Organometallics
2
014, 33, 6165−6170.
ACKNOWLEDGMENTS
■
(19) Edelbach, B. L.; Rahman, A. K. F.; Lachicotte, R. J.; Jones, W.
D. Carbon-Fluorine Bond Cleavage by Zirconium Metal Hydride
Complexes. Organometallics 1999, 18, 3170−3177.
We acknowledge the EPSRC (Grant EP/I001344, a student-
ship to C.J.E.D.) and EPSRC/University of Bath (DTA to
M.K.C.) for financial support. We thank Professor Matt Clarke
(
20) Procacci, B.; Jiao, Y. Z.; Evans, M. E.; Jones, W. D.; Perutz, R.
N.; Whitwood, A. C. Activation of B−H, Si−H, and C−F Bonds with
Tp’Rh(PMe ) Complexes: Kinetics, Mechanism, and Selectivity. J.
Am. Chem. Soc. 2015, 137, 1258−1272.
(
(
University of St. Andrews) for the kind gift of P(3,4,5-
3
C F H ) and Dr. Fedor Miloserdov and Professor Todd
6
3
2 3
Marder for useful discussions. We are particularly indebted to
Dr. Vladimir Grushin for invaluable suggestions, discussions,
and comments on the manuscript.
21) Clot, E.; Megret, C.; Kraft, B. M.; Eisenstein, O.; Jones, W. D.
Defluorination of Perfluoropropene Using Cp* ZrH and Cp* ZrHF:
2
2
2
A Mechanism Investigation from a Joint Experimental-Theoretical
Perspective. J. Am. Chem. Soc. 2004, 126, 5647−5653.
(22) Kraft, B. M.; Lachicotte, R. J.; Jones, W. D. Aliphatic and
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4
2
fluoride resonances by scavenging of trace amounts of HF or water
spectra of the isolated colorless precipitate of 7 redissolved in CD Cl
2 2
51e,57
that broaden signals as a result of hydrogen bonding.
In the case
showed the same δ −9.08 triplet hydride resonance for the cation, but
−
11
1
of 3, the addition of CsF had no effect on the appearance of the room
now the [F Bpin] anion appeared in the B{ H} NMR spectrum as
2
temperature 19F NMR spectrum recorded in toluene-d , but in
1
8
a very sharp triplet ( J = 20.8 Hz) at δ −5.1 and as a 1:1:1:1 quartet
BF
CD Cl , the Ru−F resonance sharpened to yield an obviously
with the same coupling at δ −144.4. Over a period of 10 days in
2
2
1
9
1
−
coupled, but still unresolvable, broad multiplet. In the F{ H} NMR
spectrum, this became a broadish quartet with 2JFP = 40 Hz.
Interestingly, CsF also impacted the appearance of the Ru−H signal
in CD Cl (there was no effect in toluene); rather than a quartet, a
solution, [F Bpin] appeared to convert into a second, unknown
2
anion, which showed a sharp quartet boron signal at δ −0.5 with J
=
BF
9.6 Hz, with the corresponding 1:1:1:1 quartet being at δ −146.3 in
1
9
2
2
the F NMR spectrum.
signal of higher multiplicity was now apparent, which became a
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2
31
broadish doublet with J = 13.1 Hz upon P decoupling (see
HF
Figure S18). The addition of excess PPh to each of these samples
3
4
3 3
1
19
made no impact on the appearance of either the H or F NMR
spectra in dichloromethane, but in toluene, a more coupled (albeit
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́
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1
still broad) Ru−H signal was apparent in the H NMR spectrum,
3
4
2
1
9
1
while the Ru−F signal tended toward a broad quartet in the F{ H}
Reinvestigation. Organometallics 2014, 33, 7279−7283.
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NMR spectrum.
3
1
2
(
62) The presence of three P NMR signals [δ 62.1 (br dt, J
=
PP
2
2
2
239 Hz, J = 18 Hz), 43.8 (dt, J = 239 Hz, J = 16 Hz), 38.5
PP PP PP
2
2
(
dd, J = 18 Hz, J = 16 Hz)], together with a second-order Ru−
PP
PP
H resonance (almost coincidental with that for Ru(PPh ) H ) for 4a,
3
4
2
suggests that it is formed upon substitution of P(3,4,5-C F H ) into
6
3
2 3
an axial site of Ru(PPh ) H . 4b showed two multiplet Ru−H signals
3
4
2
(
(
δ −8.8 and −10.8), which simplified to a 1:1 ratio of two doublets
HH
2 31
J
= 8.4 Hz) upon P decoupling, suggestive of an equatorially
substituted isomer. 5, which was was only ever observed at very low
concentrations, is tentatively assigned as the bisequatorially
substituted complex Ru(PPh ) {P(3,4,5-C F H ) } H on the basis
(78) Both phosphorus resonances appeared as broad singlets at 298
K.
3
2
6
3
2
3
2
2
K
DOI: 10.1021/acs.inorgchem.8b02286
Inorg. Chem. XXXX, XXX, XXX−XXX

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DOI: 10.1021/acs.inorgchem.8b02286
Inorg. Chem. XXXX, XXX, XXX−XXX