Activation of C-F and Ni-C bonds of [P,S]-ligated nickel perfluorometallacycles

Article abstract of DOI:10.1021/om400933k

The first example of a [P,S]-ligated metal perfluorocyclopentane is reported. The new metallacycle undergoes C_α-F activation in the presence of a Lewis acid, followed by chemoselective ligand migration, affording a fused metallabicyclic product. Reactivity of this product includes an unprecedented nucleophile-induced ring-opening reaction, involving loss of a β-fluoride. Additionally, hydrolysis of the metallabicyclic product affords a single isomer of hexafluoro-1-butene.

Full text of DOI:10.1021/om400933k

Article
pubs.acs.org/Organometallics
Activation of C−F and Ni−C Bonds of [P,S]-Ligated Nickel
Perfluorometallacycles
Kaitie A. Giffin, Daniel J. Harrison, Ilia Korobkov, and R. Tom Baker*
Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, 30 Marie Curie, Ottawa, Ontario
K1N 6N5, Canada
S
* Supporting Information
ABSTRACT: The first example of a [P,S]-ligated metal
perfluorocyclopentane is reported. The new metallacycle
undergoes Cα−F activation in the presence of a Lewis acid,
followed by chemoselective ligand migration, affording a fused
metallabicyclic product. Reactivity of this product includes an
unprecedented nucleophile-induced ring-opening reaction,
involving loss of a β-fluoride. Additionally, hydrolysis of the
metallabicyclic product affords a single isomer of hexafluoro-1-
butene.
Scheme 1
INTRODUCTION
■
The importance of fluorocarbons and their derivatives can be
seen through their wide range of uses: small-molecule
fluorocarbon derivatives are employed, for example, as
refrigerants, solvents, surfactants, and pharmaceutical com-
pounds.1 Despite the attractive features of fluorocarbons and
their derivatives (e.g., thermal and chemical/biochemical
stability), their syntheses are typically energetically intensive
and environmentally problematic.2 High temperatures or large
electrochemical potentials are needed, along with toxic
reagents. For example, the Swarts process for synthesizing
highly fluorinated organic compounds requires antimony-based
catalysts with chlorocarbon and hydrofluoric acid feedstocks.3
These harsh conditions are also incompatible with most
functional groups. Our goal is to develop more sustainable
routes to functionalized small-molecule fluorocarbons via base-
metal catalysis, using fluoroalkenes obtained from waste
fluoropolymers (e.g., PTFE) as feedstocks.4 We are currently
studying the stoichiometric reactions of new nickel polyfluor-
ocyclopentane complexes, with emphasis on challenging C−F
and M−RF (RF = fluoroalkyl) activation processes, to assess
their viability for future catalytic applications.
workers demonstrated the activation of a Cα−F bond in
Ni(PEt3)2(CF2)4 using BF3; upon fluoride abstraction, one of
the phosphine ligands migrated to the α-carbon, giving the
phosphonium ylide Ni(PEt3)(BF4)[CF(PEt3)(CF2)3], and a
transient fluorocarbene was proposed as an intermediate.8
Baker et al. later developed a catalytic method for the
hydrodimerization of TFE, with perfluoronickelacyclopentane
and NiL4 intermediates (Scheme 1).9 The reaction required
elevated temperatures/pressures and hydrogenolysis of the
typically robust Ni−RF bonds was only observed when π-acidic
phosphite ligands were employed.9,10 Catalysis with transition-
metal perfluoroalkyl intermediates is inherently challenging due
to the general stability of M−RF (RF = fluoroalkyl) bonds,11,18a
In the 1960s, Stone and co-workers synthesized the first
nickel perfluorometallacycles by reacting tetrafluoroethylene
(CF2CF2, TFE) with tetrakis(phosphine)- or tetrakis-
(phosphite)nickel(0) complexes (Scheme 1, top). Various
metal systems were studied, including nickel, platinum, cobalt,
and iron. It was concluded that the choice of metal and ancillary
ligands dictated whether three- or five-membered metallacycles
were formed.5 Since these compounds surfaced nearly five
decades ago, very few studies have focused on their reactivity
and most reports have been limited to substitution of the
ancillary ligands.6 Reactions of the typically inert perfluor-
ometallacyclic fragment are even rarer.7 In 1988, Burch and co-
Received: September 17, 2013
© XXXX American Chemical Society
A
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but a number of new metal-based methods for introducing RF
(predominantly CF3) groups to organic molecules have
appeared recently.12
unlikely (on the basis of previous reports of sulfonium salts and
metal-coordinated thioethers),16 we propose that the thioether
group rapidly coordinates/decoordinates from the metal,
resulting in the apparent equivalence of the two faces of the
perfluorometallacycle. The 31P{1H} signal for 2 (44.0 ppm) is
an apparent quintet due to coupling with the fluorines on the
Cα atoms. Complex 2 was characterized by single-crystal X-ray
diffraction (Figure 1).17 Crystals were grown by slow
RESULTS AND DISCUSSION
■
One approach to metal-catalyzed fluorocarbon synthesis
involves metallacycle modification through C−F bond
functionalization prior to hydrogenolysis. As a result, we have
initiated extensive studies of fluoride abstraction as a function
of metal and ancillary ligands. Herein we report the first nickel
perfluorometallacycle complex with a bidentate [P,S] ligand.
Most6b of the previously reported complexes with the
perfluoronickelacyclopentane substructure have two identical
monodentate ancillary ligands or a symmetrical bidentate ligand
(e.g., 2,2′-bipyridine or 1,2-bis(diphenylphosphino)ethane;
ideal C2v symmetry for the complexes). The reactivity of the
[P,S]-ligated metallacycle has been examined, and below we
describe several reactions, including the activation of Cα−F and
M−C bonds, as well as an unusual ring-opening reaction that
appears to proceed through β-fluoride elimination.
The bis(phosphite)nickel perfluorometallacycle 1 was
synthesized according to reported methods.3,9 Treatment of 1
with the thiol form of the ligand, 1,2,4-(HS)(Ph2P)Me(C6H3)
(variation of the known ligand 1,2-(HS)(Ph2P)(C6H4))13 led
to unexpected migration of an isopropyl group of the phosphite
ligand to the sulfur atom of the ligand, cleanly yielding complex
2 (86% isolated yield). The diisopropyl phosphonate side
product was observed by 31P{1H} NMR at 1.1 ppm with an
equimolar amount of free phosphite appearing at 135.8 ppm.
The mechanism for the formation of 2 is speculative at this
point but likely involves a transient nickel-coordinated thiol,
which is deprotonated by the phosphite; the resulting
phosphorus acid then transfers an alkyl group to the nickel-
bound thiolate (Scheme 2).14 This proposed mechanism is
Figure 1. ORTEP representation of the molecular structure of
complex 2. Ellipsoids are set at the 40% probability level, and
hydrogen atoms are omitted. Selected bond lengths (Å) and angles
(deg): Ni1−C23 1.9204(14), Ni1−C26 1.9470(13), Ni1−S1
2.2147(3), Ni1−P1 2.2194(3), C26−F1 1.3852(17), C26−F2
1.3897(17), C23−F7 1.3743, C23−F8 1.3823(18); C23−Ni1−C26
85.82(6), C26−Ni1−S1 91.12(4), C23−Ni1−P1 93.57(4), S1−Ni1−
P1 89.860(13).
evaporation of a diethyl ether solution. Bond angles are
consistent with a distorted-square-planar Ni(II) center. As
expected,11 the Cα−F bonds are significantly elongated in
comparison to Cβ−F bonds (e.g., 1.3897(17) and 1.3507(18)
Å, respectively). The Ni(1)−C(26) bond in 2 is appreciably
longer than the Ni(1)−C(23) bond trans to the sulfur donor
(1.9470(13) and 1.9204(14) Å, respectively), reflecting the
larger trans influence of the phosphine in comparison to the
thioether.
Scheme 2
When the [P,S] perfluorometallacycle 2 was treated with the
Lewis acid Me3SiOTf (Tf = SO2CF3), a fluoride was abstracted
from the metallacycle, presumably from one of the metal-
activated Cα positions,18 yielding the fused metallabicyclic
complex 3 in 95% isolated yield (48 h, 60 °C in toluene)
(Scheme 3, top). At this stage, it is not clear which of the α-
fluoride atoms is activated: the Cα−F bond lengths in the solid-
state structure of 2 are very similar for the carbon atoms trans
to P and S and thus offer no insight into the likely site of
fluoride abstraction. When BF3−etherate was employed as the
Lewis acid, the BF4-ligated analogue of 3 was not formed and
only minor, unidentified products were observed (C6D6, 60 °C,
<10% conversion of starting material after 48 h). Complex 3 is
air-stable and did not decompose upon heating (80 °C) in
CD3CN for 24 h.
The reactivity described above is reminiscent of Burch’s
observation of monodentate phosphine (PEt3) migration upon
fluoride abstraction (see above).8 Interestingly, fluoride
abstraction/phosphine migration was not observed when excess
BF3 was combined with perfluoronickelacyclopentane bearing a
bidentate [P,P] ligand {Ni[κ2-(i-Pr)2PCH2CH2P(i-Pr)2)]-
(CF2)4}, even upon heating.8 The failure of the [P,P] complex
to undergo fluoride abstraction derives presumably from the
similar to the organic Michaelis−Arbuzov reaction, which
involves formation of a phosphonate from a trialkyl phosphite
and an alkyl halide; the potently electrophilic P-alkylated
phosphite transfers another alkyl group to the halide.15
The 19F NMR data for 2 are consistent with the loss of
symmetry (apparent Cs) relative to 1 (C2v) and show four
unique fluorine environments. Considering that the nickel-
coordinated sulfur atom is chiral and pyramidal inversion is
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Scheme 3
Figure 2. ORTEP representation of the molecular structure of
complex 3. Ellipsoids are set at the 40% probability level, and
hydrogen atoms are omitted. Two phenyl groups are omitted from P1
for clarity. One of two orientations of the disordered OTf group is
depicted. Selected bond lengths (Å) and angles (deg): Ni1−C23
1.9160(15), Ni1−C26 1.9149(15), Ni1−S1 1.2777(4), P1−C23
1.8494(14); O1−Ni1−S1 84.49(14), C23−Ni1−S1 93.58(4), O1−
Ni1−C26 95.07(15), C23−Ni1−C26 86.73(6).
increased Lewis basicity and/or size of the phosphine groups,
relative to the P and S donors in 2. However, BF3 also failed to
abstract fluoride from complex 2 (see above) and it is possible
the [P,P] metallacycle could be activated using Me3SiOTf.
Burch proposed the fluoride-activation reaction proceeds
through a short-lived nickel fluorocarbene.8 In keeping with
this proposal, we speculate that the reaction proceeds through
one of two possible intermediates: a fluorocarbene (Scheme 3,
bottom left) or a carbocation intermediate19 (Scheme 3,
bottom right). The highly electrophilic18a,20 intermediate is
attacked, chemoselectively, by the more nucleophilic phosphine
group of the [P,S] ligand to give 3.
Scheme 4
The 19F NMR spectrum of 3 shows eight unique fluorine
environments (including the CF3 from the triflate group),
consistent with loss of apparent mirror-plane symmetry (Cs to
C1) and the formation of a new chiral carbon center upon
phosphine migration. Again, the sulfur atom is chiral, but the
1H NMR data show only two methyl environments for the S-
bound isopropyl group, indicating either the formation of only
one diastereomer or rapid racemization at sulfur (see above).16
Geminal F−F (2JFF) coupling constants range between 250 and
275 Hz, and the fluorine geminal to P is shifted significantly
upfield to −198.4 ppm (2JFP = 69 Hz). All seven of the
metallacyclic fluorine environments were assigned by 19F
NOESY NMR experiments (see the Supporting Information
for complete details).
Single crystals of 3 were obtained by slowly cooling a
benzene solution. Distorted-square-planar geometry is again
observed at the Ni center. For the Ni−C−P fragment, the Ni−
C bond is approximately the same length or shorter than the
three Ni−CF2RF bonds in structures 2 and 3 (Figure 2).
Presumably, the weak trans influence of the OTf ligand
contributes to the short metal−carbon bond, although the
effects of replacing a fluoride with a phosphine substituent are
unclear at present.
We began to explore the reactivity of complex 3, initially
focusing on ligand substitution reactions with a variety of
nucleophiles. Dissolving 3 in acetonitrile leads to displacement
of the triflate ion with acetonitrile to yield 3·CH3CN (Scheme
4, left). Substitution of the triflate group was also observed
when 3 was treated with 1 equiv of 2,6-dimethylphenyl
isocyanide (CNAr) or sodium thiophenolate, to afford 4 and 5,
respectively (Scheme 4). Thus, the triflate ion of 3 can be
displaced from nickel by a variety of nucleophiles, while the
thioether group remains coordinated in the products.
When 3 is treated with >1 equiv of CNAr, a surprising
ligand−induced ring-opening reaction occurs, in which Ni−S,
Ni−C, and Cβ−F bonds are cleaved and P−F/C−C bonds are
formed. Treatment of 3 with 3 equiv of CNAr yields complex 6
(room temperature, 1 h, C6D6) (Scheme 5, top right), which
was observed using multinuclear NMR.21,22 Evidence for the
P−F group is provided by 19F and 31P NMR: the large coupling
constant of 660 Hz is strongly indicative of one-bond P−F
coupling and the downfield 19F shift of +16.5 ppm also
supports a fluorine−phosphorus bond. The 31P{1H} NMR
resonance for 6 is found significantly upfield at −73.8 ppm,
suggestive of a five-coordinate phosphorus atom.23 For the
3
alkenyl fluorine atoms, JFF = 135 Hz, pointing to exclusive
formation of the F,F-trans (E) double-bond isomer. Attempts
to isolate 6 led to decomposition; we obtained the more stable
compound 7 (91% isolated yield) by fluoride abstraction from
the phosphorus center of 6, using Me3SiOTf (Scheme 5).
C
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Scheme 5
EXPERIMENTAL SECTION
■
General Considerations. Experiments were conducted under
nitrogen, using Schlenk techniques or an MBraun glovebox. All
solvents were deoxygenated by purging with nitrogen. Toluene,
hexanes, diethyl ether (DEE), and tetrahydrofuran (THF) were dried
on columns of activated alumina using a J. C. Meyer (formerly Glass
Contour) solvent purification system. Benzene-d6 (C6D6) and
dichloromethane (DCM) were dried by stirring over activated alumina
(ca. 10 wt %) overnight, followed by filtration. Acetonitrile (MeCN)
and acetonitrile-d3 (CD3CN) were dried by refluxing over calcium
hydride under nitrogen. After distillation, they were dried further by
stirring over activated alumina (ca. 5 wt %) overnight, followed by
filtration. All solvents were stored over activated (heated at ca. 250 °C
for >10 h under vacuum) 4 Å molecular sieves. Glassware was oven-
dried at 150 °C for >2 h. The following chemicals were obtained
commercially, as indicated: trimethylsilyl trifluoromethanesulfonate
(Me3SiOTf, Aldrich, 99%), bis(1,5-cyclooctadiene)nickel (Ni(COD)2,
Strem, 98+%), triisopropyl phosphite (P(O-i-Pr)3, Aldrich, 95%), 4-
methylbenzenethiol (1,4-(HS)Me(C6H4), Aldrich, 98%), diphenyl-
chlorophosphine (PPh2Cl, Strem, minimum 95%), 2,6-dimethylphenyl
isocyanide (1,2,6-(CN)Me2(C6H3), Aldrich, 96%), sodium thiophe-
nolate (NaSPh, Aldrich, ≥96.5%). Tetrafluoroethylene was purchased
from ABCR (99%) or made by pyrolysis of polytetrafluoroethylene
(Scientific Polymer Products, powdered) under vacuum, using a
slightly modified literature procedure (10−20 mTorr, 650 °C, 30 g
scale, product stabilized with (R)-(+)-limonene (Aldrich, 97%), giving
TFE of ca. 97% purity).26 Ni[P(O-i-Pr)3]2(C4F8) was made by
oxidative addition of tetrafluoroethylene to Ni[P(O-i-Pr)3]4 using a
slightly modified literature procedure.3,9 Ni[P(O-i-Pr)3]4 was prepared
from Ni(COD)2 following reported methods. 31H, 19F, 31P{1H}, and
13C{1H} NMR spectra were recorded on a 300 MHz Bruker Avance
1
Complex 7 was characterized by H, 19F, and 31P{1H} NMR,
UV−vis, and ESI-MS.
Upon hydrolysis, 3 releases exclusively the F,F-trans (E)
double-bond isomer fluoroalkene shown in Scheme 5 (bottom)
and as yet uncharacterized byproducts.24 This is the first
example of a transition-metal-mediated process for the selective
formation of (E)-1,2,3,3,4,4-hexafluoro-1-butene.25 An experi-
ment with D2O confirms that the hydrogens of the product
originate from water. We suspect the obtained NMR yield of
the hydrofluoroalkene (27% based on three trials) is artificially
low due to liquid−gas phase partitioning and/or super-
saturation of the benzene solvent. The crude 19F NMR
spectrum for the hydrolysis reaction showed only minor
impurities and (E)-1,2,3,3,4,4-hexafluoro-1-butene as the only
major product (see the Supporting Information, Figures S29
and S30).
Treating complex 7 with water does not generate (E)-
1,2,3,3,4,4-hexafluoro-1-butene. 19F and 31P{1H} NMR data
indicate that an intact P−C(F) bond is present among the
unknown hydrolysis products, on the basis of geminal coupling
between the phosphorus and one fluorine atom (see the
Supporting Information for additional details).
1
instrument at room temperature (21−23 °C). H NMR spectra were
referenced to the residual proton peaks associated with the deuterated
solvents (C6D6, 7.16 ppm; CD3CN, 1.94 ppm). 19F NMR spectra were
referenced to internal 1,3-bis(trifluoromethyl)benzene (BTB) (Al-
drich, 99%, deoxygenated by purging with nitrogen, stored over
activated 4 Å molecular sieves), set to −63.5 ppm. Note: for NMR
solutions containing both BTB and hexafluorobenzene (C6F6)
(Aldrich, 99%), the chemical shift of C6F6 appears at −163.6 or
−164.5 ppm, in C6D6 and CD3CN, respectively (with BTB at −63.5
ppm). 1H NMR data for BTB: at 300 MHz, C6D6, δ 6.60 (m, 1H, Ar-
5-H), 7.12 (m, 2H, Ar-4,6-H), 7.76 (m, 1H, Ar-2-H); at 300 MHz,
CD3CN, δ 7.76−7.84 (m, 1H, Ar-H), 7.95−8.04 (ov m, 3H, Ar-H).
We chose BTB as an internal 19F NMR standard over C6F6 because we
expected it to be less reactive with any of the reported Ni complexes or
reactive intermediates. 31P{1H} NMR data were referenced to external
H3PO4 (85% aqueous solution), set to 0.0 ppm. Electrospray
ionization mass spectral data were collected using an Applied
Biosystem API2000 triple-quadrupole mass spectrometer. UV−vis
spectra were recorded on a Cary 100 instrument, using sealable quartz
cuvettes (1.0 cm path length). Elemental analyses were performed by
Canadian Microanalytical Service Ltd. (Delta, British Columbia,
Canada).
CONCLUSIONS
■
In summary, the synthesis of a new nickel perfluorometallacycle
(2), with a hemilabile phosphine/thioether ligand, has been
described. Fluoride abstraction from this complex yielded a
phosphine migration product (3), featuring weakly bound
thioether and triflate groups on the nickel atom. Ligand
substitution studies revealed that the triflate ligand may be
displaced from the metal, producing neutral or cationic
complexes by employing different nucleophiles. The reaction
of 3 with CNAr (≥3 equiv) produced an unexpected ring-
opened product via Ni−C and C−F activation pathways.
Finally, hydrolysis of 3 afforded a single isomer of hexafluoro-1-
butene, thus demonstrating the potential of metallacycle
modification for selective production of unsaturated hydro-
fluorocarbons. A combined experimental and computational
study is underway to elucidate the mechanism for this
unprecedented ring-opening reaction. The stoichiometric
systems reported here will be studied more extensively with
the goal of designing catalytic systems for the synthesis of
functionalized fluorocarbons.
X-ray Crystallography. For 2 and 3, samples were mounted on
thin glass fibers using paraffin oil and were cooled to 200 K prior to
data collection. Data were collected on a Bruker AXS KAPPA single-
crystal diffractometer equipped with a sealed Mo tube source
(wavelength 0.71073 Å) APEX II CCD detector. Raw data collection
and processing were performed with the APEX II software package
from BRUKER AXS.27 Diffraction data were collected with a sequence
of 0.5° ω scans at 0, 90, 180, and 270° in ϕ. Initial unit cell parameters
were determined from 60 data frames collected at the different
sections of the Ewald sphere. Semiempirical absorption corrections
based on equivalent reflections were applied. Systematic absences in
the diffraction data set and unit-cell parameters were consistent with
triclinic systems. Solutions in centrosymmetric space group yielded
chemically reasonable and computationally stable results of refine-
ment. The structures were solved by direct methods, completed with
difference Fourier synthesis, and refined with full-matrix least-squares
D
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procedures based on F.27 In the structure, compound molecules are
situated in the general position. All non-hydrogen atoms were refined
anisotropically with satisfactory thermal parameter values. Additional
crystallographic data and selected data collection parameters are
reported below. The CIF files for 2 and 3 are available as Supporting
Information.
(3; 50 mg, 0.068 mmol) was dissolved in ∼8 mL of dichloromethane
(DCM) and transferred to a 50 mL round-bottom flask. To the 3/
DCM solution was added 1 equiv of 2,6-dimethylphenyl isocyanide
(CNAr; 9 mg, 0.068 mmol). No significant color change was observed.
The reaction mixture was stirred at room temperature for 12 h. The
product was concentrated, dried in vacuo, and stored at room
temperature under nitrogen. Yield: 53 mg, 0.061 mmol, 90% based on
3. UV−vis (0.7 mM in dichloromethane): λmax (ε) 352 nm (1118). 1H
NMR (300 MHz, CD2Cl2): δ 1.52, 1.55 (d, J = 7 Hz, 3H, i-Pr Me),
2.31 (s, 6H, CNAr Me), 2.39 (s, 3H, Me), 3.75 (sept, 1H, i-Pr H), 7.06
(d, 2JPH = 14 Hz, 1H, Ar-H), 7.2 (d, 2H), 7.34 (m, 1H, Ar-H), 7.51−
8.08 (ov m, 12H, Ar-H). 19F NMR (282 MHz, CD2Cl2): δ −79.0 (s,
3F, OTf), −87.5 (br d, 2JFF = 257 Hz, 1Fα), −94.2 (d tr, 2JFF = 257 Hz,
JFF = 10 Hz, 1Fα), −116.9 (d m, 2JFF = 275 Hz, 1Fβ), −128.8 (d m, 2JFF
= 275 Hz, 1Fβ), −132.5 (br AB doublets, 2JFF ≈ 262 Hz, 2Fβ), −199.0
Synthesis of [1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F8) (2). [(P(O-
i-Pr)3)2Ni(C4F8)] (1; 1.00 g, 1.48 mmol) was placed in a 100 mL
round-bottom flask and dissolved in ∼10 mL of toluene. [1,2,4-
(HS)(Ph2P)Me(C6H3)] (480 mg, 1.56 mmol) was added to the
stirred [(P(Oi-Pr)3)2Ni(C4F8)]/toluene mixture, and stirring was
continued at room temperature for ∼12 h. The cloudy yellow-orange
reaction mixture was concentrated in vacuo until ∼2 mL of yellow
paste remained. Around 20 mL of hexanes was then added to the
round-bottom flask, precipitating a light yellow powder. The flask was
placed in a −35 °C freezer for 24 h. The product was filtered cold (30
mL medium pore fritted funnel), washed with precooled hexanes (−35
°C, 2 × 3 mL), and dried in vacuo, affording a light yellow powder.
Yield: 776 mg, 1.27 mmol, 86% based on 1. The isolated material was
stored at room temperature under nitrogen. UV−vis (0.7 mM in
diethyl ether): λmax (ε) 332 nm (2082). 1H NMR (300 MHz, C6D6): δ
0.96 (d, J ≈ 7 Hz, 6H, 2 i-Pr Me), 1.64 (s, 3H, Me), 3.58 (sept, 1H, i-
Pr H), 6.60 (d m, 1H, Ar-H), 6.98 (ov m, 8H, Ar-H), 7.60 (ov m, 4H,
Ar-H). 19F NMR (282 MHz, C6D6): δ −96.3 (d m, 2Fα, 3JFP = 32 Hz),
3
2
(d d, JFF = 31 Hz, JFP = 67 Hz, 1Fα). 31P{1H} NMR (121
MHz,CD2Cl2): δ 17.2 (d d d, 2JPF = 67, 3JPF = 17, 10 Hz). See Figures
S11−S13 (Supporting Information) for the 1H, 19F, and 31P{1H}
spectra. MS-ESI (positive mode, solvent CH3OH): m/z calcd for
{[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)](CNAr)Ni(C4F7)}+ (% intensity),
720.1 (100), 722.1 (51), 721.1 (39), 723.1 (20); m/z found, 720.2
(100), 722.3 (51), 721.3 (39), 723.4 (22).
Synthesis of [1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)](SPh)Ni(C4F7) (5).
[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F7)(OTf) (3; 70 mg, 0.095
mmol) was dissolved in ∼6 mL of acetonitrile and transferred to a 50
mL round-bottom flask. To the above solution was added sodium
thiophenolate (13 mg, 0.099 mmol). An immediate color change from
light orange to bright red was observed. The reaction mixture was
stirred at room temperature for 12 h. The solution was concentrated in
vacuo, and the product was extracted with dichloromethane,
precipitating out the sodium triflate salt. The dichloromethane
solution was filtered through a Celite Pasteur pipet and concentrated
in vacuo in a round-bottom flask. Hexanes was added (∼20 mL),
precipitating out a light orange solid. The flask was placed in a −35 °C
freezer for 12 h. The product was filtered cold (15 mL medium pore
fritted funnel) and washed with ∼3 mL of hexanes. The light orange
powder was dried in vacuo and stored at room temperature under
nitrogen. Yield: 44 mg, 0.063 mmol, 67% based on 3. UV−vis (0.7
mM in acetonitrile): λmax (ε) 310 (5886) (shoulder on off-scale signals
in the UV range), 353 (2551) (shoulder/tail), 515 nm (322). 1H
NMR (300 MHz, CD3CN): δ 1.33, 1.38 (d, J ≈ 7 Hz, 3H, i-Pr Me),
2.28 (s, 3H, Me), 4.15 (sept, J ≈ 7 Hz, 1H, i-Pr H), 6.82 (ov m, 3H,
Ar-H), 6.93 (ov m, 2H, Ar-H), 7.17 (d, JHP ≈ 14 Hz, 1H, Ar-H), 7.46−
7.69 (ov m, 6H, Ar-H), 7.86 (ov m, 3H, Ar-H), 8.00 (m, 1H, Ar-H),
8.32 (ov d, 2H, Ar-H). 19F NMR (282 MHz, CD3CN): δ −93.0 (d m,
3
−104.7 (d m, 2Fα, JFP = 27 Hz), −137.8 (m, 2Fβ), −138.6 (m, 2Fβ).
31P{1H} NMR (121 MHz, C6D6): δ 44.0 (tr tr, 3JPF = 27, 32 Hz). Anal.
Calcd for C26H23F8NiPS: C, 51.26, H, 3.81. Found: C, 51.48, H, 3.65.
1
See Figures S1−S3 (Supporting Information) for the H, 19F, and
31P{1H} spectra.
Synthesis of [1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F7)(OTf) (3).
[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F8) (2; 831 mg, 1.36 mmol)
was dissolved in ∼20 mL of toluene and transferred to a 100 mL
Schlenk bomb (i.e., a tubular flask, sealed with a single polytetrafluoro-
ethylene (PTFE) valve). To the 2/toluene solution was added
trimethylsilyl trifluoromethanesulfonate (296 μL, 1.64 mmol). The
bomb was sealed and placed in a 60 °C oil bath for 48 h. A dark yellow
precipitate was formed over the course of the reaction time. The
product was filtered through a 30 mL medium pore fritted funnel
under nitrogen. The collected dark yellow powder was washed with
hexanes (2 × 3 mL) and dried in vacuo. Yield: 958 mg, 1.30 mmol,
95% based on 2. The isolated material was stored at room temperature
1
under nitrogen. H NMR (300 MHz, CD2Cl2): δ 1.59, 1.74 (d, J = 7
Hz, 3H, i-Pr Me), 2.33 (s, 3H, Me), 3.81 (sept, J = 7 Hz, 1H, i-Pr H),
7.06 (d, JHP = 14 Hz, 1H, Ar-H), 7.47−8.00 (ov m, 10H, Ar-H), 8.39
(ov d m, 2H, Ar-H). 19F NMR (282 MHz, CD2Cl2): δ −78.5 (s, 3F,
OTf), −99.2 (d tr, 2JFF = 242 Hz, 3JFF = 12 Hz, 1Fα), −115.6 (d d, 2JFF
2
3
2JFF = 269 Hz, 1Fα), −114.6 (d d d, JFF = 269 Hz, JFF = 20, 5 Hz,
1Fα), −117.3 (d m, JFF = 270 Hz, 1Fβ), −130.4 (d m, 2JFF = 270 Hz,
2
3
2
= 242 Hz, JFF = 17 Hz, 1Fα), −117.8 (d m, JFF = 272 Hz, 1Fβ),
1Fβ), −130.9 (d m, 2JFF = 244 Hz, 1Fβ), −135.9 (d m, 2JFF = 244 Hz,
−129.9 (d m, 2JFF = 272 Hz, 1Fβ), −132.5 (d d d, 2JFF = 245 Hz, 3JFF
=
1Fβ), −198.8 (d d, JFP = 73 Hz, JFF = 36 Hz, 1Fα). 31P{1H} NMR
(121 MHz, CD3CN): δ 13.5 (d tr, 2JPF = 73, 3JPF = 15 Hz). See Figures
S14−S16 (Supporting Information) for the 1H, 19F, and 31P{1H}
spectra. MS (ESI (positive mode), solvent CH3CN): m/z calcd for
{[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F7)+} (% intensity), 589.0
(100), 591.0 (43), 590.1 (28); m/z found, 589.8 (100), 591.7 (48),
590.8 (43).
2
3
35, 16 Hz, 1Fβ), −137.3 (d m, 2JFF = 245 Hz, 1Fβ), −196.2 (d d d, 2JFP
= 75 Hz, 3JFF = 31, 7 Hz, 1Fα). 31P{1H} NMR (121 MHz, CD2Cl2): δ
14.8 (d tr, 2JPF = 75, 3JPF = 14 Hz). Anal. Calcd for C27H23F10NiO3PS2:
C, 43.87, H, 3.14. Found: C, 43.73, H, 2.95. See Figures S4−S6
(Supporting Information) for the H, 19F, and 31P{1H} spectra.
1
{[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)](CD3CN)Ni(C4F7)}+(OTf)− (3·
CD3CN). [1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F7)(OTf) (3; 10
mg, 0.0135 mmol) was dissolved in deuterated acetonitrile. UV−vis
(0.7 mM in acetonitrile): λmax (ε) 396 nm (907). 1H NMR (300 MHz,
CD3CN): δ 1.18 (d d, J ≈ 7, 1 Hz, 3H, i-Pr Me), 1.38 (d, J ≈ 7 Hz,
3H, i-Pr Me), 2.34 (s, 3H, Me), 3.43 (sept, 1H, i-Pr H), 7.29 (d d m,
1H, Ar-H), 7.5−8.1 (ov m, 10H, Ar-H), 8.35 (ov d m, 2H, Ar-H). 19F
NMR (282 MHz, CD3CN): δ −79.4 (s, 3F, OTf), −96.8 (d tr m, 2JFF
Observation of 6. [1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F7)-
(OTf)) (3; 20 mg, 0.027 mmol) was dissolved in deuterated benzene
(∼1 mL) in a medium screw cap vial, and 2,6-dimethylphenyl
isocyanide (CNAr) (12 mg, 0.095 mmol) was added. The color
changed immediately from opaque yellow to clear orange. The
reaction mixture was stirred at room temperature for 30 min and then
transferred to a J. Young NMR tube to obtain NMR spectra of
3
2
3
= 250 Hz, JFF = 12 Hz, 1Fα), −109.2 (d d, JFF = 250 Hz, JFF = 16
1
Hz, 1Fα), −118.5 (d m, 2JFF = 273 Hz, 1Fβ), −130.0 (d tr m, 2JFF = 273
compound 6. See Figures S18−S20 (Supporting Information) for H,
19F, and 31P{1H} spectra. NMR data in benzene-d6 are as follows.
(broad peaks in fluorine and proton spectra associated with
intermediate(s) en route to 6 are not reported; integrations for
proton peaks are not reported due to overlap between product peaks
from 6 and broad intermediate peaks). 1H NMR (300 MHz, C6D6): δ
0.95 (d, J = 7 Hz, i-Pr Me), 2.15 (s, Me), 2.22 (s, CNAr Me), 3.11
(sept, i-Pr H), 6.62−6.69 (ov m, Ar-H), 6.77−6.83 (m, Ar-H), 7.66−
3
2
Hz, JFF = 15 Hz, 1Fβ), −132.4 (d m, JFF = 248 Hz, 1Fβ), −135.8 (d
2
2
3
m, JFF = 248 Hz, 1Fβ), −198.4 (d d m, JFP = 69 Hz, JFF = 30 Hz,
1Fα). 31P{1H} NMR (121 MHz, CD3CN): δ 15.8 (d tr, 2JPF = 69, 3JPF
1
= 13 Hz). See Figures S7−S10 (Supporting Information) for the H,
19F, 31P{1H}, and 19F−19F NOESY spectra.
Synthesis of {[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)](CNAr)Ni-
(C4F7)}+(OTf)− (4). [1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F7)(OTf)
E
dx.doi.org/10.1021/om400933k | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
7.78 (ov m, Ar-H). 19F NMR (282 MHz, C6D6): δ 14.5 (br d, JFP
=
and 13C{1H} spectra. MS (ESI (positive mode), solvent CH3CN): m/
z calcd for [M + H+], 165.0; m/z found, 165.4.
660 Hz, 1F), −55.9 (br s, 2Fα), −78.3 (s, 3F, OTf), −105.0 (d d, 4JFF
= 27, 3JFF = 11 Hz, 2Fβ), −128.2 (br d, 3JFF(trans) = 135 Hz, 1F), −151.2
3
(br d, JFF(trans) = 135 Hz, 1F). 31P{1H} NMR (121 MHz, C6D6): δ
ASSOCIATED CONTENT
* Supporting Information
■
−73.3 (br d, JPF1 = 660 Hz). See Figures S17−S19 (Supporting
S
Information) for H, 19F, and 31P{1H} spectra.
CIF files for 2 and 3 giving crystallographic data, a table giving
structure refinement details, text giving experimental details for
the reaction of 3 with D2O, and Figures S1−S33 containing
NMR spectra of all reported products. This material is available
free of charge via the Internet at http://pubs.acs.org.
Synthesis of {[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)][1,2,6-(CN)-
(Me)2(C6H3)]3Ni(C4F6)}2+(OTf)− (7). [1,2,4-(i-Pr-S)(Ph2P)Me-
2
(C6H3)]Ni(C4F7)(OTf) (3; 70 mg, 0.095 mmol) was dissolved in
∼10 mL of C6H6 in a 50 mL round-bottom flask. A 3.5 equiv portion
of 2,6-dimethylphenyl isocyanide (CNAr) (44 mg, 0.333 mmol) was
added, and the reaction mixture was stirred for 20 min at room
temperature. To the 3/CNAr benzene solution was added
trimethylsilyl trifluoromethanesulfonate (18.9 μL, 0.104 mmol). The
reaction mixture was stirred at room temperature for 14 h. The
product was concentrated in vacuo and washed with 2 × 3 mL of
benzene, affording a yellow-gold solid. Yield: 109 mg, 0.086 mmol,
91% based on 3. UV−vis (0.7 mM in acetonitrile): λmax (ε) 369
(2233) (shoulder on off-scale signals in UV range), 453 nm (1018).
1H NMR (300 MHz, CD3CN): δ 0.93 (d, J = 7 Hz, 6H, i-Pr Me), 2.32
(s, 3H, Me), 2.41 (ov s, 18H, CNAr Me), 3.17 (sept, 1H, i-Pr H), 7.23
(ov m, 6H, Ar-H), 7.36 (ov m, 5H, Ar-H), 7.75 (ov m, 9H, Ar-H),
7.94 (ov m, 2H, Ar-H). 19F NMR (282 MHz, CD3CN): δ −58.7 (br s,
AUTHOR INFORMATION
Corresponding Author
*E-mail for R.T.B.: rbaker@uottawa.ca.
■
Author Contributions
The manuscript was written through contributions of all
authors. All authors have given approval to the final version of
the manuscript.
Notes
The authors declare no competing financial interest.
4
3
2Fα), −79.4 (s, 6F, OTf), −107.3 (d d, JFF = 23, JFF = 11 Hz, 2Fβ),
3
4
ACKNOWLEDGMENTS
−133.9 (d m, JFF(trans) = 144, JFF = 11 Hz, 1F), −151.0 (d t t,
■
3JFF(trans) = 144 Hz, JFP = 60 Hz, JFF = 23, JFF = 8 Hz, 1F). 31P{1H}
2
3
We thank the NSERC and the Canada Research Chairs
program for generous financial support and the University of
Ottawa, Canada Foundation for Innovation, and Ontario
Ministry of Economic Development and Innovation for
essential infrastructure. D.J.H. thanks the province of Ontario
and the University of Ottawa for a Vision 2020 Postdoctoral
Fellowship.
2
3
NMR (121 MHz, CD3CN): δ 15.6 (d d, JPF = 60, JPF = 7 Hz). See
Figures S20−S22 (Supporting Information) for the 1H, 19F, and
31P{1H} spectra. MS (ESI (positive mode), solvent CH3CN): m/z
calcd for [{[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)][1,2,6-(CN)-
(Me)2(C6H3)]3Ni(C4F6)}2+(OTf)− − H + K+], 1150.2; m/z found,
1150.5; m/z calcd for [{[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)][1,2,6-(CN)-
(Me)2(C6H3)](CH3CN)2Ni(C4F6)}2+], 783.2; m/z found, 782.9; m/z
calcd for [{[1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)][1,2,6-(CN)-
(Me)2(C6H3)](CH3CN)2Ni(C4F6)}2+ + K+], 822.1, m/z found,
821.9; m/z calcd for [{1,2,4-(i-Pr-S)(Ph2P)Me-(C6H3)][1,2,6-(CN)-
(Me)2(C6H3)} + H+], 133.1; m/z found, 133.3; m/z calcd for [{1,2,4-
(i-Pr-S)(Ph2P)Me(C6H3)][1,2,6-(CN)(Me)2(C6H3)} − 2CH3],
102.0, m/z found, 102.1.
REFERENCES
■
(1) Chambers, R. D. Fluorine in Organic Chemistry, 2nd ed.;
Blackwell: Oxford, U.K., 2004.
(2) Kitazume, T. J. Fluorine Chem. 2000, 105, 265.
(3) Chambers, R. D.; Burton, D. J.; Drakesmith, F. G.; Hutchinson,
J.; Kitazume, T.; Lu, L.; Percy, J. M.; Sandford, G.; Yamazaki, T.
Organofluorine Chemistry Techniques and Synthons; Springer: New
York, 1997; Vol. 193.
(4) (a) Siegle, J. C.; Muus, L. T.; Lin, T. P.; Larsen, H. A. J. Polym.
Sci., Part A: Polym. Chem. 1964, 2, 391. (b) Lonfei, J.; Jingling, W.;
Shuman, X. J. Anal. Appl. Pyrol. 1986, 10, 99. (c) Meissner, E.;
Wroblewska, A.; Milchert, E. Polym. Degrad. Stab. 2004, 83, 163.
́
(d) Bhadury, P. S.; Singh, S.; Sharma, M.; Palit, M. J. Anal. Appl. Pyrol.
2007, 78, 288.
(5) (a) Green, M.; Osborn, R. B. L.; Rest, A. J.; Stone, F. G. A. J.
Chem. Soc. A 1968, 2525. (b) Ashley-Smith, J.; Green, M.; Stone, F. G.
A. J. Chem. Soc. A 1969, 3019. (c) Browning, J.; Cundy, C. S.; Green,
M.; Stone, F. G. A. J. Chem. Soc. A 1969, 20. (d) Cundy, C. S.; Green,
M.; Stone, F. G. A. J. Chem. Soc. A 1970, 1647. (e) Greco, A.; Green,
M.; Shakshooki, S. K.; Stone, F. G. A. J. Chem. Soc. D 1970, 1374.
(f) Stone, F. G. A. J. Fluorine Chem. 1999, 100, 227. (g) Ohashi, M.;
Shibata, M.; Saijo, H.; Kambara, T.; Ogoshi, S. Organometallics 2013,
32, 3631.
(6) (a) Green, M.; Shakshooki, S. K.; Stone, F. G. A. J. Chem. Soc. A
1971, 2828. (b) Davies, C. H.; Game, C. H.; Green, M.; Stone, F. G.
A. J. Chem. Soc., Dalton Trans. 1974, 357.
(7) Stone reported reactivity studies of a related tetracarbonyl iron
perfluorocyclopentane complex. The product decomposed with
heating at 70 °C for 120 h, affording perfluorocyclobutane as the
major organic product. With heating at 160 °C for 12 days,
perfluorocyclobutene was obtained as the major organic product:
Manuel, T. A.; Stafford, S. L.; Stone, F. G. A. J. Am. Chem. Soc. 1961,
83, 249.
Hydrolysis of [1,2,4-(i-Pr-S)(Ph2P)Me(C6H3)]Ni(C4F7)(OTf) (3).
3 (60 mg, 0.081 mmol) was transferred to a 50 mL Schlenk bomb
(with a side arm) in a minimal amount of deuterated benzene (∼2
mL). To the 3/benzene solution was added 0.2 mL of water. The flask
was sealed, and the contents were stirred at 75 °C for 72 h. The
reaction mixture was cooled to room temperature, and the flask was
connected directly to the Schlenk line. Three freeze−pump−thaw
cycles were performed on the flask. J. Young NMR tube was then
evacuated and cooled to −196 °C. With the bomb and J. Young tube
both under vacuum, ∼0.5 mL of the reaction mixture was transferred
to the J. Young tube under static vacuum, isolating (E)-1,2,3,3,4,4-
hexafluoro-1-butene from the nickel-containing and other nonvolatile
byproducts. An 19F NMR yield (by integration of product CF2 peaks
relative to an internal standard) of 27% based on three trials was
calculated. Note: no reaction occurred upon addition of an excess of
1
water to 2 with heating. NMR data in benzene-d6 (a crude H NMR
spectrum taken before vacuum transfer is shown in Figure S23
(Supporting Information)) are as follows. 1H NMR (300 MHz,
C6D6): δ 0.44 (s, H2O), 5.06 (tr tr m, 2JHF = 53, 3JHF = 3 Hz, 1H), 6.19
(d d m, JHF = 71, 4 Hz, 1H). 19F NMR (282 MHz, C6D6): δ −122.1
(m, JFH = 3 Hz, 2F), −137.3 (d m, 2JFH = 53 Hz, 2F), −166.8 (d d tr tr,
3
3JFH(gem) = 71 Hz, JFF(trans) = 135 Hz, JFF = 21, 4 Hz, 1F), −178.5 (d
m, 3JFH(cis) = 4 Hz, 3JFF(trans) = 135 Hz, 1F). 19F{1H} NMR (282 MHz,
C6D6): δ −122.1 (m, 2F), −137.3 (m, 2F), −166.8 (d tr tr, 3JFF(trans)
=
135 Hz, JFF = 21, 4 Hz, 1F), −178.5 (d tr tr, JFF(trans) = 135 Hz, 1F).
13C{1H} NMR (75 MHz, C6D6): δ 109.2 (tr tr d, JCF = 251 Hz, 2JCF
=
38 Hz, 3JCF = 3 Hz, 1C), 142.9 (d d, JCF = 244 Hz, 2JCF(trans) = 33 Hz,
1C), 144.8 (d d tr, JCF = 264 Hz, 2JCF(trans) = 59 Hz, 3JCF = 3 Hz, 1C).
(8) Burch, R. R.; Calabrese, J. C.; Ittel, S. D. Organometallics 1988, 7,
1642.
1
See Figures S23−S30 (Supporting Information) for H, 19F, 19F{1H},
F
dx.doi.org/10.1021/om400933k | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(9) Baker, R. T., Beatty, R. P., Farnham, W. B.; Wallace, R. L., Jr. (E.
I. Du Pont de Nemours & Co.) PCT Int. Appl. U.S. Patent 5,670,679,
1997. The preparation of unsaturated hydrofluorocarbons (HFCs) is
an attractive target, as several such molecules have been shown to have
drastically reduced global warming potential (vs saturated HFCs):
http://www.unep.org/dewa/portals/67/pdf/HFC_report.pdf.
(10) Gasafi-Martin, W.; Oberendfellner, G.; Von Werner, K. Can. J.
Chem. 1996, 74, 1922.
(23) Burton, D. J.; Yang, Z. Y.; Qiu, W. Chem. Rev. 1996, 96, 1641
and references therein.
(24) No reaction occurred upon addition of an excess of water to 2
with heating. Burch observed an ancillary ligand substitution reaction
upon reacting his phosphine ligand migration product with an excess
of water, resulting in the cationic complex [Ni(PEt3)(H2O)(CF(PEt3)
(CF2)3)]+[BF4]−.8
(25) Miller, R. N.; Nappa, M. J.; Rao, V. N. M.; Sievert, A. C. (E. I.
Du Pont de Nemours & Co.) U. S. Pat. Appl. Publ., U.S. Patent
2006106263, 2006.
(11) Kiplinger, J. L.; Richmond, T. G.; Osterberg, C. E. Chem. Rev.
1994, 94, 373.
(26) Hunadi, R. J.; Baum, K. Synthesis 1982, 39, 454.
(27) APEX Software Suite v.2010; Bruker AXS, Madison, WI, 2005.
(12) (a) Dubinina, G. G.; Furutachi, H.; Vicic, D. A. J. Am. Chem. Soc.
2008, 130, 8600. (b) Dubinina, G. G.; Ogikubo, J.; Vicic, D. A.
Organometallics 2008, 27, 6233. (c) Oishi, M.; Kondo, H.; Amii, H.
Chem. Commun. 2009, 1909. (d) Ball, N. D.; Kampf, J. W.; Sanford, M.
S. J. Am. Chem. Soc. 2010, 132, 2878. (e) Cho, E. J.; Senecal, T. D.;
Kinzel, T.; Zhang, Y.; Watson, D. A.; Buchwald, S. L. Science 2010,
328, 1679. (f) McReynolds, K. A.; Lewis, R. S.; Ackerman, L. K. G.;
Dubinina, G. G.; Brennessel, W. W.; Vicic, D. A. J. Fluorine Chem.
2010, 131, 1108. (g) Knauber, T.; Arikan, F.; Roschenthaler, G. V.;
̈
Gooßen, L. J. Chem. Eur. J. 2011, 17, 2689. (h) Zhang, C. P.; Wang, Z.
L.; Chen, Q. Y.; Zhang, C. T.; Gu, Y. C.; Xiao, J. C. Angew. Chem., Int.
́
Ed. 2011, 50, 1896. (i) Tomashenko, O. A.; Escudero-Adan, E . C.;
Belmonte, M. M.; Grushin, V. V. Angew. Chem., Int. Ed. 2011, 50,
7655. (j) Morimoto, H.; Tsubogo, T.; Litvinas, N. D.; Hartwig, J. F.
Angew. Chem., Int. Ed. 2011, 50, 3793. (k) Xu, J.; Luo, D. F.; Xiao, B.;
Liu, Z. J.; Gong, T. J.; Fu, Y.; Liu, L. Chem. Commun. 2011, 47, 4300.
(l) Dai, J. J.; Fang, C.; Xiao, B.; Yi, J.; Xu, J.; Liu, Z. J.; Lu, X.; Liu, L.;
Fu, Y. J. Am. Chem. Soc. 2013, 135, 8436.
(13) Block, E.; Ofori-Okai, G.; Zubieta, J. J. Am. Chem. Soc. 1989,
111, 2327.
(14) (a) McFarlane, W.; White, R. F. M. J. Chem. Soc. D 1969, 744.
(b) Olah, G. A.; McFarland, C. W. J. Org. Chem. 1971, 36, 1374.
(c) Weiss, R.; Van de Griend, L. J.; Verkade, J. G. J. Org. Chem. 1979,
44, 1860.
(15) (a) Arbusow, B. A. Pure Appl. Chem. 1964, 9, 307.
(b) Bhattacharya, A. K.; Thyagarajan, G. Chem. Rev. 1981, 81, 415.
(16) (a) Darwish, D.; Hong Hui, S.; Tomilson, R. J. Am. Chem. Soc.
1968, 90, 5631. (b) Stirling, C. J. M. The Chemistry of the Sulphonium
Group, Part 1; Wiley: Chichester, U.K., 1981. (c) Toru, T.; Bolm, C.;
̀
Briere, J.-F.; Metzner, P. Synthesis and Use of Chiral Sulfur Ylides. In
Organosulfur Chemistry in Asymmetric Synthesis; Wiley-VCH: Wein-
heim, Germany, 2008; pp 179−208 and references therein.
́ ́
(d) Arevalo, R.; Perez, J.; Riera, L. Inorg. Chem. 2013, 52, 6785.
(17) Additional crystallographic details can be found in the
Supporting Information: for complex 2, R = 0.0297, for complex 3,
R = 0.0644.
(18) (a) Clark, G. R.; Hoskins, S. V.; Roper, W. R. J. Organomet.
Chem. 1982, 234, C9. (b) Brothers, P. J.; Roper, W. R. Chem. Rev.
1988, 88, 1293. (c) Garratt, S. A.; Hughes, R. P.; Kovacik, I.; Ward, A.
J.; Willemsen, S.; Zhang, D. J. Am. Chem. Soc. 2005, 127, 15585.
(d) Torrens, H. Coord. Chem. Rev. 2005, 249, 1957. (e) Hughes, R. P.
J. Fluorine Chem. 2010, 131, 1059. (f) Huang, D.; Koren, P. R.; Folting,
K.; Davidson, E. R.; Caulton, K. G. J. Am. Chem. Soc. 2000, 122, 8916.
(g) Taw, F. L.; Clark, A. E.; Mueller, A. H.; Janicke, M. T.; Cantat, T.;
Scott, B. L.; Hay, P. F.; Hughes, R. P.; Kiplinger, J. L. Organometallics
2012, 31, 1484.
́
(19) (a) Nieto-Oberhuber, C.; Lοpez, S.; Jimen
Echavarren, A. M. Chem. Eur. J. 2006, 12, 5916. (b) Furstner, A.;
́
ez-Nunez, E.;
́
̃
̈
Morency, L. Angew. Chem., Int. Ed. 2008, 47, 5030.
(20) Harrison, D. J.; Gorelsky, S. I.; Lee, G. M.; Korobkov, I.; Baker,
R. T. Organometallics 2013, 32, 12.
(21) Reacting 3 with >1 equiv of sodium thiophenolate results in
very minor consumption of 4 to give an uncharacterized product.
(22) Dissolving 3 in pyridine results in the formation of an analogous
ring-opened product. Initial variable-temperature NMR experiments in
THF suggest the presence of more than one metallacyclic intermediate
en route to 6. Further details are provided in the Supporting
Information.
G
dx.doi.org/10.1021/om400933k | Organometallics XXXX, XXX, XXX−XXX