Successive insertion of tetrafluoroethylene and CO and of tetrafluoroethylene and acetylenes into aryne-nickel(0) bonds

Article abstract of DOI:10.1039/a702375h

Aryne-nickel complexes [Ni(η²-C₆H₄)L₂] [L₂ = 2PEt₃ or dcpe; dcpe = (C₆H¹¹)²PCH₂CH₂P(C ₆H₁₁)₂] and [Ni(η²-C₁₀H₆)(PEt₃)₂] reacted readily with C₂F₄ to form the corresponding five-membered tetrafluoro-substituted nickelacycles [Ni(C₆H₄CF₂CF₂-2)L₂] (L₂ = dcpe or 2PEt₃) and [Ni(2-C₁₀H₆CF₂CF₂-3)(PEt ₃)₂], respectively. The complex [Ni(C₆H₄CF₂CF₂-2)(dcpe)] is very stable towards air, whereas the PEt₃ analogues react readily to give μ-aryloxo dimers. The naphthalene-based dimer [{Ni(μ-2-OC¹⁰H₆CF₂CF₂-3)(PEt ₃)}₂] has been structurally characterized. The complexes [Ni(C₆H₄CF₂CF₂-2)L₂] insert CO into their aryl-nickel bonds to form six-membered acyl complexes [Ni{C(O)C₆H₄CF₂CF₂-2} L₂] (L₂ = dcpe or 2PEt₃) and, after CO-induced reductive elimination, 2,2,3,3-tetrafluoroindanone. The dcpe acyl complex has also been shown to undergo reaction with air to form the carboxylato complex [Ni{OC(O)C₆H₄CF₂CF₂-2}(dcpe)], whose structure has been confirmed by X-ray crystallography. Some insertions of acetylenes into the aryl-nickel bonds of [Ni(C₆H₄CF₂CF₂-2)L₂] are also reported.

Full text of DOI:10.1039/a702375h

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Successive insertion of tetrafluoroethylene and CO and of
tetrafluoroethylene and acetylenes into aryne–nickel(0) bonds†
Martin A. Bennett,* Margaret Glewis, David C. R. Hockless and Eric Wenger
Research School of Chemistry, Australian National University, GPO Box 414, Canberra,
A.C.T. 2601, Australia
Aryne–nickel complexes [Ni(η2-C6H4)L2] [L2 = 2PEt3 or dcpe; dcpe = (C6H11)2PCH2CH2P(C6H11)2] and
[Ni(η2-C10H6)(PEt3)2] reacted readily with C2F4 to form the corresponding five-membered tetrafluoro-substituted
nickelacycles [Ni(C6H4CF2CF2-2)L2] (L2 = dcpe or 2PEt3) and [Ni(2-C10H6CF2CF2-3)(PEt3)2], respectively. The
complex [Ni(C6H4CF2CF2-2)(dcpe)] is very stable towards air, whereas the PEt3 analogues react readily to give
µ-aryloxo dimers. The naphthalene-based dimer [{Ni(µ-2-OC10H6CF2CF2-3)(PEt3)}2] has been structurally
characterized. The complexes [Ni(C6H4CF2CF2-2)L2] insert CO into their aryl–nickel bonds to form six-
membered acyl complexes [Ni{C(O)C6H4CF2CF2-2}L2] (L2 = dcpe or 2PEt3) and, after CO-induced reductive
elimination, 2,2,3,3-tetrafluoroindanone. The dcpe acyl complex has also been shown to undergo reaction with air
to form the carboxylato complex [Ni{OC(O)C6H4CF2CF2-2}(dcpe)], whose structure has been confirmed by X-ray
crystallography. Some insertions of acetylenes into the aryl–nickel bonds of [Ni(C6H4CF2CF2-2)L2] are also
reported.
Arynenickel(0) bis(tertiary phosphine) complexes, Ni(η2-
F
F
(C6H11 2
)
aryne)L2, which are generated by alkali-metal reduction of the
corresponding (2-bromoaryl)nickel() halide compounds, react
readily with unsaturated molecules.1–4 For example, the benzyne
complexes [Ni(η2-C6H4)L2] [L2 = 2PEt3 1 or dcpe 2; dcpe =
(C6H11)2PCH2CH2P(C6H11)2] undergo double insertion with
acetylenes to form, after reductive elimination, a substituted
naphthalene,2,4 and the 2,3-didehydronaphthalene complexes
[Ni(2,3-η-C10H6)L2] (L2 = 2PEt3 3 or dcpe 4) similarly give sub-
stituted anthracenes.3 We have shown that tetrafluoroethylene
reacts with 4 to form the five-membered tetrafluoro-substituted
P
C2F4
F
F
Ni
Ni
P
(C6H11)2P
P(C6H11)2
(C6H11 2
)
4
5
MeO2CC2CO2Me
F
F
F
nickelacycle [Ni(2-C10H6CF2CF2-3)(dcpe)] 5, which in turn
undergoes insertion with dimethyl acetylenedicarboxylate under
vigorous conditions (50 ЊC, 16 h) to give the seven-membered
F
(C6H11 2
)
P
Ni
P
ring nickelacycle [Ni{3-C(CO Me)᎐C(CO Me)C H CF CF -
᎐
2
2
10
6
2
2
(C6H11 2
)
2}(dcpe)] 6 (Scheme 1). Double insertions of this type seemed
to offer a route to novel fluoro-substituted indanones and
dihydronaphthalenes. We report here on the reaction of C2F4
with 1–3 and on the reactions of the resulting tetrafluoro-
nickelaindanes with CO and with acetylenes.
MeO2C
CO2Me
6
Scheme 1
F
F
L
L
L
C2F4
Results
F
F
Ni
Insertion of C2F4
Ni
L
Reaction of the benzynenickel(0) complex [Ni(η2-C6H4)(dcpe)] 2
with C2F4 at Ϫ20 ЊC and subsequent warming to room tem-
1: L = PEt3
2: 2L = dcpe
7: 2L = dcpe
8: L = PEt3
perature gave the nickelaindane complex [Ni(C6H4CF2CF2-
2)(dcpe)] 7, which was isolated in 61% yield as an air-stable,
yellow solid (Scheme 2). The 19F NMR spectrum contains a
doublet of triplets at δ Ϫ103.84 [J(FP) 6, J(FF ) 11 Hz] for the
benzylic CF2 group and a doublet of doublets of triplets at δ
Ϫ93.35 [J(FP) 32, 21, J(FF ) 11 Hz] corresponding to the CF2
attached to the nickel. The 31P NMR spectrum shows two sig-
nals, a doublet of triplets of triplets at δ 64.47 [J(PP) 12, J(FP),
32, 5 Hz] and a doublet of triplets at δ 68.38 [J(PP) 12, J(FP) 21
Hz]. The magnitude of the P᎐P coupling shows that the phos-
Scheme 2
phorus atoms are mutually cis; the more shielded resonance,
which shows coupling to both CF2 groups, probably corre-
sponds to the phosphorus atom trans to CF2. These data are
similar to those for [Ni(2-C10H6CF2CF2-3)(dcpe)] 5.3 In one
reaction, the nickelacycle [Ni(CF2CF2CF2CF2)(dcpe)] was also
isolated as a by-product, possibly arising from the reaction
of C2F4 with [Ni(dcpe)2] present as an impurity in 2. Simi-
lar products have been obtained from the reaction of C2F4
with nickel(0) complexes such as [Ni(η4-1,5-C8H12)2] and
[Ni(PEt3)4].5
† In memoriam: Geoff Wilkinson, pioneer of organotransition metal
chemistry.
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114
3105

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F
PEt3
PEt3
F
1. C2F4
2. air
Ni
F
F
2
F
F
Ni
PEt3
3
O2
F
F
O
2
O
Ni
Et3P
– OPEt3
Ni
F
F
PEt3
F
Et3P
F
F
F
8
F
F
Ni
PEt3
O
9a (syn-isomer)
9b (anti-isomer)
O
Ni
Et3P
F
Scheme 3
F
F
F
Complex 1 also reacted readily with C2F4 to give the corre-
10a (syn-isomer)
10b (anti-isomer)
sponding yellow nickelaindane [Ni(C6H4CF2CF2-2)(PEt3)2]
8 in 83% yield (Scheme 2), which shows 19F NMR signals at
δ Ϫ105.24 and Ϫ94.58 due to the CF2 groups. The 31P NMR
spectrum contains a doublet of triplets of triplets at δ 7.75
[J(PP) 22, J(FP) 35, 5 Hz] for the phosphorus trans to the
CF2 unit and an apparent quartet at δ 11.48 (separation = 23
Hz), indicative of mutually cis-PEt3 ligands. In contrast with its
dcpe analogue, complex 8 is very sensitive to traces of air.
Under those conditions, two new species, 9a and 9b, were
formed in almost equal amounts (Scheme 3). They were charac-
terized in their 31P-{1H} NMR spectra by a triplet at δ 28.07
[J(FP) 30.5 Hz] and a doublet of doublets at δ 29.12 [J(FP) 31,
16 Hz], respectively. The 19F NMR spectrum of 9a shows only a
very broad singlet at δ Ϫ98.65, whereas that of 9b consists of
complex signals for each of the four inequivalent fluorines.
Although the proportions of 9a and 9b did not change when
the solution was heated, passage through a silica gel column
afforded only 9b; the quantity recovered suggested that 9a had
isomerized to 9b, not that it had merely undergone selective
decomposition. During the reaction of 8 with air an intermedi-
ate having two multiplets at δ 23.0 and 31.3 in its 31P NMR
spectrum was detected.
Scheme 4
F
F
F
F
NiI(dcpe)
I2
F
F
F
F
Ni
I
(C6H11)2P
P(C6H11)2
12
Cl-
F
7
F
F
F
Cl
NiCl(dcpe)
F
F
F
F
I
I
13
Scheme 5
The nickel–aryl bond of compound 7 is cleaved by iodine to
give [NiI(CF2CF2C6H4I-2)(dcpe)] 12 (Scheme 5), which was
identified tentatively on the basis of its NMR spectroscopic
data. The 31P NMR spectrum in CD2Cl2 shows two doublets of
triplets, at δ 65.5 [J(PP) 38, J(FP) 27 Hz] (P trans to CF2) and δ
84.6 [J(PP) 38, J(FP) 27 Hz] (P trans to I). The 19F NMR spec-
trum has a singlet at δ Ϫ92.4 and a triplet at δ Ϫ76.3 [J(FP) 27
Hz], and the fragment Ni(CF2CF2C6H4I)(dcpe) (m/z 783)
appears in the electron impact (EI) mass spectrum. Complex 12
is not very stable; in CDCl3 the 31P NMR signals broaden and
new doublets of triplets appear at δ 63.5 [J(PP) 45, J(FP) 28 Hz]
and 81.1 [J(PP) 45, J(FP) 23 Hz]. The shift upfield of the
phosphorus trans to the halogen is consistent with the form-
ation of the corresponding chloro-complex [NiCl(CF2CF2-
C6H4I-2)(dcpe)] 13. This decomposed on attempted chrom-
atography on silica gel to give an organic species having singlets
in its 19F NMR spectrum at δ Ϫ99.3 and Ϫ56.7. The latter
signal is in the range expected for a CF2X group, indicating that
2-IC6H4CF2CF2Cl may have been formed, but the reaction was
not investigated further.
Reaction of the 2,3-didehydronaphthalene complex [Ni-
(η2-C10H6)(PEt3)2] 3 with C2F4 in the presence of air gave
a similar pair of compounds, 10a and 10b, which showed in
their 31P NMR spectra a triplet at δ 28.23 and a doublet of
doublets at δ 29.05, respectively. Compound 10b was isolated
in 51% yield by recrystallization from dichloromethane and
was shown by X-ray crystallography (see below) to be the
µ-aryloxo dimer [{Ni(µ-2-OC10H6CF2CF2-3)(PEt3)}2]. This is
presumably formed from the initial insertion product
[Ni(2-C10H6CF2CF2-3)(PEt3)2] (analogous to the dcpe com-
pound 5) by loss of PEt3, insertion of an oxygen atom into the
nickel–aryl bond, and dimerization of the resulting three-
co-ordinate Ni(2-OC10H6CF2CF2-3)(PEt3) units (Scheme 4).
The crystal structure of 10b (see below) shows that the two
naphthalene rings are on the same side of the Ni2O2 plane, i.e.
they adopt a syn arrangement having a C2 axis; we assume that
in 10a they are in the alternative centrosymmetric anti dis-
position. The similarity of the 31P NMR parameters strongly
suggests that 9a and 9b are the corresponding syn and anti
Reactions with CO
isomers of [{Ni(µ-OC6H4CF2CF2-2)(PEt3)}2]. Closely related to
our observations are the reported reactions of the metallacycle
[Ni(C6H4CMe2CH2-2)(PMe3)2] 11 with formaldehyde6 and
nitrous oxide.7 In the first case, insertion occurs at the nickel–
alkyl, not the nickel–aryl, bond.6 The dimeric µ-alkoxo product,
The dcpe complex 7 reacts slowly with CO under atmospheric
pressure at 50 ЊC (Scheme 6). Monitoring by IR and NMR
spectroscopy showed the formation of a complex believed to be
the chelate acyl [Ni{C(O)C6H4CF2CF2-2}(dcpe)] 14, in add-
ition to [Ni(CO)2(dcpe)]. The IR spectrum shows a strong
ν(C᎐O) band at 1615 cmϪ1, which shifts to 1570 cmϪ1 for
[{Ni(C6H4CMe2CH2O-2)(PMe3)}2], also exists as two isomers
in solution, which were proposed to be syn and anti isomers
arising from the meso and rac arrangements of the two nickela-
᎐
the species 14a generated by use of 13CO, and the 13C NMR
spectrum of 14a contains a doublet of doublets of triplets at
δ 256.6 [J(CP) 76, 18, J(CF ) 5.5 Hz], which is assigned to
the acyl carbon atom. The IR and chemical shift data are
similar to those reported for acylnickel() complexes,8–12 e.g. for
cycloheptene rings. In the second case,
a di-µ-aryloxo-
nickel() complex [{Ni(µ-OC6H4CMe2CH2)(PMe3)}2] is formed
by transfer of an oxygen atom to the nickel–aryl bond,7 but
apparently only one isomer of this compound was observed.
trans-[NiCl(COPh)(PMe ) ] the ν(C᎐O) is at 1600 cmϪ1 and
᎐
3
2
3106
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114

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F
F
F
F
F
F
F
F
L
L
Ni
O
CO2Me
MeO2C
15
18
+ Ni(CO)2L2
SiO2
dmad
2L = dcpe
CO
F
F
F
L
F
F
F
F
F
F
F
L
F
F
Ni
F
F
CO2Me
CO
L
L
Ni
CO2Me
Ni
dmad
L = PEt3
7: 2L = dcpe
8: L = PEt3
L
19
L
O
7: 2L = dcpe
8: L = PEt3
14: 2L = dcpe
17: L = PEt3
F
F
F
F
+ 19 + ...
O2
CO2Me
2L = dcpe
CO2Me
20
F
F
F
Scheme 7
F
(C6H11 2
)
P
Ni
[Ni{4,5-F2-OC(O)C6H2C(O)O-2}(dcpe)] formed by aerial oxi-
P
O
dation of the bis(acyl) [Ni{4,5-F2-C(O)C6H2C(O)-2}(dcpe)].12
The 31P NMR spectrum of 16 shows two multiplets at δ 63.7 (P
trans to CF2) and 77.8 (P trans to carboxylate), the chemical
shift of the latter being identical with that of the phthalato
complex. The magnitude of the J(PP) (40 Hz) confirms that the
phosphorus atoms are mutually cis.
The PEt3 complex 8 reacts rapidly with CO (1 bar) at
room temperature, giving an inseparable mixture of 15 and
[Ni(CO)2(PEt3)2]. An intermediate, probably the acyl
(C6H11 2
)
O
16
Scheme 6
δC(COPh) is 253.0 [J(PC) 26.5 Hz].10 The 31P NMR spectrum
of 14 contains triplets at δ 58.8 [J(FP) 37] and 56.8 [J(FP)
29.5 Hz], these chemical shifts being similar to that of the phthal-
oylnickel() complex [Ni{4,5-F2-C(O)C6H2C(O)-2}(dcpe)] (δ
58.9).12 These signals appear as doublets of triplets in the 31P
NMR spectrum of 14a [J(CP) 76 and 19 Hz, respectively], the
smaller coupling being to the phosphorus atom cis to the acyl
carbon {cf. the value for trans-[NiCl(COPh)(PMe3)2]10}.
Unfortunately, there appear to be no literature values of J(CP)
for trans-[P᎐Ni᎐COR] complexes for comparison, but for
related platinum() complexes J(PC) for trans and cis arrange-
ments have been reported as 107 and 7 Hz, respectively.13 The
19F NMR spectrum of 14 consists of a broad singlet at δ
Ϫ102.1 and a broad triplet of triplets at δ Ϫ94.7, the separation
due to P᎐F coupling [‘J(FP)’] being 33 Hz. In 14a, the second
resonance appears as a doublet of triplets of triplets with
‘J(FP)’ 33, J(FF ) 9 and J(CF ) 5.5 Hz. The small magnitude of
J(FC) is consistent with the expected cis C(O)᎐Ni᎐CF2
arrangement. When a sample containing 14 was left under
nitrogen for 16 h its 31P NMR spectrum showed that the
amount of 14 had decreased and the starting complex 7 had
reformed. This observation can be accounted for if the inser-
tion of CO into the nickel–aryl bond is reversible.
[Ni{C(O)C6H4CF2CF2-2}(PEt3)2] 17, was observed; it showed
two singlets in the 19F NMR spectrum at δ Ϫ96.84 and Ϫ105.23
and a broad singlet at δ 7.75 in the 31P NMR spectrum.
Reactions with acetylenes
The dcpe nickelaindane
7 failed to react with tert-
butylacetylene, even after several days in refluxing tetra-
hydrofuran (thf), but with dimethyl acetylenedicarb-
oxylate
(dmad)
the
expected
insertion
product
[Ni{2-C(CO Me)᎐C(CO Me)C H CF CF }(dcpe)] 18 was
᎐
2
2
6
4
2
2
formed in >80% yield as estimated by 31P NMR spectro-
scopy (Scheme 7). Complex 18 was identified from the
similarity of its NMR parameters (see Experimental section)
with those of the naphthalene analogue 6.3 Unfortunately, it
proved impossible to separate 18 from an unidentified red
polymeric oil. Attempted chromatography on silica gel gave
small amounts of a substituted naphthalene having two doub-
lets at δ Ϫ144.1 and Ϫ144.7 [J(FF ) 19 Hz] in its 19F NMR
spectrum, probably dimethyl 3,4-difluoronaphthalene-1,2-
dicarboxylate 19. This could be formed by the reductive elimin-
ation of Ni(dcpe) and subsequent aromatization, with loss of
two atoms of fluorine, on silica gel.
Work-up of the air-sensitive reaction mixtures obtained from
complex 7 and CO (3–4 bar; bar = 101 325 Pa) at 50 ЊC gave
mixtures, in varying proportions, of two compounds: 2,2,3,3-
tetrafluoroindanone 15, identified by the band at 1759 cmϪ1
in its IR spectrum and by its 19F NMR and mass spectra, and
The PEt3 complex 8 is considerably more reactive than 7
towards acetylenes, as is true for the reactions with CO. Reac-
tion with dmad gave immediately a complex mixture that
appeared to contain the dihydronaphthalene 3,3,4,4-F4-1,2-
(CO2Me)2C10H4 20 in addition to 19 and other unidentified
species (Scheme 7). tert-Butylacetylene gave, after silica gel
chromatography, 4-tert-butyl-1,2-difluoronaphthalene 21, pre-
sumably formed by insertion of the acetylene into the nickel–
aryl bond as for 6 and 18 and subsequent reductive elimination
and aromatization on silica (Scheme 8). The alternative regio-
the chelate carboxylato complex [Ni{OC(O)C6H4CF2CF2-2}-
(dcpe)] 16, whose structure has been confirmed by X-ray crystal-
lography (see below). Both arise from 14, the former by CO-
induced reductive elimination, the latter by aerial oxidation.
The presence of the monodentate carboxylato function in 16 is
evident from a ν(C᎐O) band at 1630 cmϪ1 in the IR spectrum
᎐
and a signal at δ 172.10 in the 13C NMR spectrum. Similar
values have been recorded for the phthalatonickel() complex
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114
3107

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F
F
F
F
ButC2H
F
F
F
F
δ−
Ni δ+
Ni
But
PEt3
PEt3
Et3P
8
F
F
F
F
F
F
F
F
PEt3
PEt3
Ni
But
But
SiO2
Fig. 1 An ORTEP 15 diagram for [{Ni(µ-2-OC10H6CF2CF2-3)(PEt3)}2]
F
F
10b with atom labelling and 20% probability ellipsoids
But
21
Scheme 8
F
F
F
F
F
F
MeO2CC2H
F
F
δ−
Ni δ+
Ni
PEt3
PEt3
Et3P
δ+
CO2Me
8
Fig. 2 Side view of dimer 10b showing the cis configuration of the two
naphthalene rings. Hydrogen atoms, fluorine atoms, and ethyl groups
of the PEt3 ligands have been omitted for clarity
F
F
F
F
PEt3
Ni
MeO2CC2H
PEt3
tion of two methyl propiolate molecules (Scheme 9). The struc-
ture was assigned on the basis of its EI-mass and NMR (1H,
19F, 13C) spectra. The presence of the CF2CF2H group is
CO2Me
F
F
24
F
F
1
evident from a one-proton triplet of triplets in the H NMR
PEt3
PEt3
3
Ni
spectrum at δ 5.90 [2J(HF ) 54, J(HF ) 2.8 Hz] and a pair of
resonances at δ Ϫ134.22 [dt, J(FH) 54, J(FF ) 4 Hz, CF2H] and
CO2Me
1
Ϫ110.45 (quintet, J 4 Hz) in the 19F NMR spectrum. The H
NMR spectrum also contains a pair of 3 H singlets at δ 3.69
and 3.87 due to the OMe groups, a pair of 1 H doublets at δ
CO2Me
F
F
6.65 and 7.28 [J(HH) 16 Hz] due to a trans-CH᎐CH group, and
25
᎐
F
F
a broad triplet at δ 8.07 due to the remaining vinylic proton.
H+
– NiII(PEt3)2
H
Molecular structures of [{Ni(ì-2-OC10H6CF2CF2-3)(PEt3)}2]
10b and [Ni{OC(O)C6H4CF2CF2-2}(dcpe)] 16
MeO2C
The molecular geometry of [{Ni(µ-2-OC10H6CF2CF2-3)-
(PEt3)}2] 10b is shown in Figs. 1 and 2. Selected inter-
atomic distances and angles are given in Table 1. The molecule
occupies a general position in the unit cell. The two nickel
atoms Ni(1) and Ni(1Ј) have a distorted square-planar geom-
etry and are 0.133 and 0.062 Å, respectively, from the least-
squares plane defined by the oxygen atoms O(1) and O(1Ј), the
phosphorus atom and the carbon atom of the co-ordinated CF2
group. The dihedral angle between the co-ordination planes
intersecting at O(1) and O(1Ј) is 36.4Њ. The Ni(1)᎐Ni(1Ј)᎐
O(1)᎐O(1Ј) unit is slightly bent, the two oxygen atoms being
0.32 Å out of the plane defined by these atoms. The two
naphthalene rings are in a syn arrangement with angles of
CO2Me
22
Scheme 9
isomer, 3-tert-butyl-1,2-difluoronaphthalene, was not detected.
1
The complicated H NMR spectrum of 21 was simulated by
LAOCOON 14 as an ABCDMXY spin system and the position
of the But group at C4 was confirmed by nuclear Overhauser
experiments (see Experimental section).
Surprisingly, reaction of complex 8 with an excess of methyl
propiolate did not give a naphthalene or dihydronaphthalene,
but rather the tetrafluoroethylbenzene derivative 2-(HCF2CF2)-
C H CH᎐C(CO Me)CH᎐C(CO Me) 22, arising from the inser-
᎐
᎐
6
4
2
2
3108
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114

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Table 1 Selected bond distances (Å) and angles (Њ) for
[{Ni(µ-2-OC10H6CF2CF2-3)(PEt3)}2] 10b
Table 2 Selected bond distances (Å) and angles (Њ) for
[Ni{OC(O)C6H4CF2CF2-2}(dcpe)] 16
Ni(1Ј)᎐P(1Ј)
Ni(1Ј)᎐O(1Ј)
Ni(1)᎐P(1)
Ni(1)᎐O(1Ј)
O(1)᎐C(2)
2.183(2)
1.919(4)
2.170(2)
1.940(4)
1.357(6)
Ni(1Ј)᎐O(1)
Ni(1Ј)᎐C(10Ј)
Ni(1)᎐O(1)
Ni(1)᎐C(10)
O(1Ј)᎐C(2Ј)
1.934(4)
1.911(7)
1.894(4)
1.914(6)
1.367(6)
Ni᎐P(1)
Ni᎐O(1)
2.155(3)
1.902(7)
Ni᎐P(2)
Ni᎐C(9)
2.221(3)
1.97(1)
P(1)᎐Ni᎐P(2)
P(1)᎐Ni᎐C(9)
P(2)᎐Ni᎐C(9)
87.2(1)
91.6(3)
176.7(3)
P(1)᎐Ni᎐O(1)
O(1)᎐Ni᎐C(9)
P(2)᎐Ni᎐O(1)
173.8(3)
94.1(4)
87.3(2)
P(1Ј)᎐Ni(1Ј)᎐O(1)
P(1Ј)᎐Ni(1Ј)᎐C(10Ј)
O(1)᎐Ni(1Ј)᎐C(10Ј)
P(1)᎐Ni(1)᎐O(1)
P(1)᎐Ni(1)᎐C(10)
O(1)᎐Ni(1)᎐C(10)
Ni(1Ј)᎐O(1)᎐Ni(1)
Ni(1)᎐O(1)᎐C(2)
Ni(1Ј)᎐O(1Ј)᎐C(2Ј)
97.8(1)
92.7(2)
168.2(2)
168.2(1)
92.5(2)
93.1(2)
98.5(2)
118.9(4)
115.7(4)
P(1Ј)᎐Ni(1Ј)᎐O(1Ј)
O(1)᎐Ni(1Ј)᎐O(1Ј)
O(1Ј)᎐Ni(1Ј)᎐C(10Ј)
P(1)᎐Ni(1)᎐O(1Ј)
O(1)᎐Ni(1)᎐O(1Ј)
O(1Ј)᎐Ni(1)᎐C(10)
Ni(1Ј)᎐O(1)᎐C(2)
Ni(1Ј)᎐O(1Ј)᎐Ni(1)
Ni(1)᎐O(1Ј)᎐C(2Ј)
168.4(1)
78.3(2)
92.4(2)
96.7(1)
78.7(2)
169.7(2)
129.5(4)
97.5(2)
126.7(4)
Fig. 4 Side view of complex 16 showing the boat-shaped conform-
ation of the seven-membered nickelacycle. Hydrogen atoms and cyclo-
hexyl groups of the dcpe ligand have been omitted for clarity
all these complexes fits well with the reported values for
[Ni(CF2CF2CF2CF2)(PEt3)2] [1.948(6) Å]18 and [Ni(CF3)(η5-
C5H5)(PPh3)] [mean 1.948(22) Å].19 The Ni᎐O (carboxylate)
distance [1.902(7) Å] and other bond lengths in 16 are
unexceptional.
Discussion
Pioneering work, especially by Stone and co-workers,5,20–23 has
shown that two molecules of tetrafluoroethylene readily under-
go C᎐C coupling on reaction with nickel(0)–tertiary phosphine
complexes to form octafluoronickelacyclopentanes, but there are
relatively few examples of the coupling of C2F4 with a η2-alkene
or η2-alkyne on nickel(0). They include the reaction of
Fig. 3 An ORTEP diagram for [Ni{OC(O)C6H4CF2CF2-2}(dcpe)] 16
with atom labelling and 20% probability ellipsoids
[Ni(tmen)(η2-C2F4)]
(tmen = N,N,NЈ,NЈ-tetramethylethane-
1,2-diamine, Me2NCH2CH2NMe2) with acetylene to give the
121.4 and 63.4Њ between the planes defined by C(1)᎐C(2)᎐
C(3)᎐C(4)᎐C(4a)᎐C(8a) and C(1Ј)᎐C(2Ј)᎐C(3Ј)᎐C(4Ј)᎐C(4aЈ)᎐
C(8aЈ), respectively, and the Ni᎐O plane (Fig. 2), so that there is
almost a C2 symmetry axis at right angles to the Ni(1)᎐Ni(1Ј)
axis. The two six-membered rings Ni᎐CF2᎐CF2᎐C(2)᎐C(3)᎐O
have a boat-shaped conformation. The average Ni᎐O distance in
the six-membered ring [Ni(1)᎐O(1) and Ni(1Ј)᎐O(1Ј)] of 1.907
Å is slightly shorter than the other Ni᎐O distance [Ni(1)᎐O(1Ј)
and Ni(1Ј)᎐O(1)] of 1.937 Å. These distances are compar-
able with those found in other nickel() aryloxides, e.g.
nickelacyclopentane [Ni(CH᎐CHCF CF )(tmen)]24 and the
᎐
2
2
similar reaction of [NiL1(η2-C F )] (L1 = 2,6-Pri C H NCH᎐
᎐
2
4
2
6
3
CHNC6H3Pri2-2,6) with ethylene to give the nickelacyclo-
pentene [Ni(CH2CH2CF2CF2)L1]; the latter compound can also
be made from [NiL1(η2-C2H4)] and C2F4.25 We have extended
these observations by showing that C2F4 readily couples with
η2-2,3-didehydronaphthalene and η2-benzyne on nickel(0) to
give chelate σ-bonded nickel() complexes [Ni(2-C10H6CF2CF2-
[Ni(OC6H4CMe2CH2-2)(dmpe)] (dmpe = Me2PCH2CH2PMe2)
[1.872(3) Å]7 and trans-[Ni(OPh)Me(PMe3)2]ؒPhOH [1.932(5)
Å],16 and in the binuclear di-µ-hydroxo complex [Ni2(µ-OH)2-
(CH2C6H4Me-2)2(PMe3)2] [1.920(4), 1.917(4) Å].17
3)(dcpe)] 5 (Scheme 1) and [Ni(C6H4CF2CF2-2)L2] (L2 = dcpe 7
or 2 PEt3 8) (Scheme 2), respectively.
An interesting feature of complex 8 is its ready loss of PEt3 in
the presence of air to form the syn and anti isomers of the µ-
aryloxo-nickel() complexes, 9a and 9b, as a result of insertion
of an oxygen atom into the nickel–aryl bond. The formation of
the analogous compounds 10a and 10b from [Ni(η2-C10H6)-
(PEt3)2] 3 and C2F4 in the presence of air (Scheme 4) probably
The molecular geometry of [Ni{OC(O)C6H4CF2CF2-2}-
(dcpe)] 16 is shown in Figs. 3 and 4; selected interatomic dis-
tances and angles are given in Table 2. The seven-membered
nickelacycle has a boat-shaped conformation and the co-
ordination geometry about the nickel is close to square planar.
The Ni᎐P(1) distance trans to the carboxylate [2.155(3) Å] is
significantly less than that trans to CF2 [2.221(3) Å], consistent
with the larger trans influence of the σ-bonded carbon atom.
The Ni᎐CF2 distance in 16 [1.97(1) Å] seems to be greater than
those in 10b [1.911(7), 1.914(6) Å], 5 [1.926(3) Å]3 and 6
[1.955(4) Å],3 possibly reflecting the relative trans influences of
the aryloxide and tertiary phosphine ligands, but the range in
proceeds via the insertion product [Ni(2-C10H6CF2CF2-3)-
(PEt3)2] analogous to 5, though we did not attempt to isolate it.
The behaviour of complex 8 with oxygen contrasts with that
of the bis(σ-bonded) complexes trans-[Ni(2-MeC6H4)Me-
(PEt3)2]26 and trans-[Ni(4-MeC6H4)(C6Cl5)(PMe2Ph)2],27 which
undergo reductive elimination of o-xylene and p-MeC6H4C6Cl5,
respectively, on heating in air. There may be an analogy with the
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114
3109

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tert-butyl group is adjacent to the metal atom. A second differ-
formation of [{Ni(µ-OC6H4CMe2CH2)(PMe3)}2] from 11 and
N2O,7 in which the latter is believed to add as a heterocumulene
similarly to CO2, CS2, COS, PhNCS, PhNCO and p-MeC6H4-
NCNC6H4Me-p.28,29 Oxygen-atom insertions into the Pd᎐C σ
bonds of arylpalladium() complexes are induced by reaction
with m-chloroperbenzoic acid 30,31 or tert-butyl hydroperox-
ide;32 in the latter case the rate of oxygenation increases with
the nucleophilicity of the metal centre. It is also well known that
alkyls of main-group elements (especially those in Groups 1–
3),33,34 of titanium and zirconium (MR4),35 and of molybdenum
and tungsten (M2R6)35 undergo autoxidation to form unstable
peroxides, which react rapidly with the initial alkyl to give
finally metal alkoxides (Scheme 10). Several stable peroxo-
platinum()36,37 and -palladium()38 complexes have been
characterized. The selective oxidation of terminal olefins by
oxygen to methyl ketones in the presence of palladium(0) and
platinum(0) complexes proceeds via a five-membered peroxo-
metallacycle formed by a 1,3-dipolar reaction of a dioxygen
complex ML2(O2) with the olefin.38–40 This decomposes to give
the ketone and an oxo-metal species. In the light of these observ-
ations we suggest that the tetrafluoronickelaindane 8 inserts
oxygen into the nickel–aryl bond to give a six-membered per-
oxonickel() species 23 (Scheme 11); this may be the intermedi-
ate observed by 31P NMR spectroscopy. It could then react with
unco-ordinated PEt3 to give Et3PO and the final isomeric
aryloxonickel() complexes 9a, 9b.
ence is that the insertion of the second molecule of tert-
butylacetylene into this intermediate occurs at the nickel–vinyl
bond, not the nickel–aryl bond.2,4 Presumably, in the reaction
of 8 with tert-butylacetylene steric hindrance between the ter-
tiary phosphine and the tert-butyl group of the alkyne as it
approaches the nickel–aryl bond determines the regioselectivity.
For comparison, the reaction between [Ni(C6H4CMe2CH2-2)-
(PMe3)2] 11 and tert-butylacetylene gives a 2.2 to 1 mixture of
dihydronaphthalenes, the isomer having the tert-butyl group in
the 3 position being favoured.42 Thus, assuming that insertion
occurs into the nickel–aryl bond, attack at the sterically less
hindered alkyne carbon atom is preferred, as in the correspond-
ing insertions with 1. It is not clear whether the difference in
behaviour between 8 and 11 towards tert-butylacetylene is
caused mainly by the change from PEt3 to the less bulky PMe3.
The formation of the tetrafluoroethylbenzene derivative 22
from 8 and methyl propiolate (Scheme 9) can be accounted for
by assuming a double insertion of methyl propiolate under elec-
tronic control into the nickel–aryl bond of 8, giving successively
intermediate nickelacycles 24 and 25 in which a CO2Me group
is on the carbon atom bound to nickel. Subsequent protonation
then gives 22. The source of the proton is not known, however,
and it is not clear why protonation should take precedence over
ring closure in this case.
The fact that CO and dmad insert exclusively into the nickel–
aryl bond of complex 5, not the Ni᎐CF2 bond, is consistent
with the well known reluctance of transition metal–fluoroalkyl
bonds (and, more generally, bonds to electron-withdrawing
alkyl groups) to undergo insertion of CO.41 The same regio-
selectivity undoubtedly applies in the case of 8, whose tendency
to lose PEt3 causes it to be far more reactive than 5 towards
insertion of acetylenes such as tert-butylacetylene and methyl
propiolate. Surprisingly, in the former case, the nickel–aryl
bond must attack exclusively the sterically more hindered
alkyne carbon atom bearing the tert-butyl group. This con-
trasts with the reactions of tert-butylacetylene with [Ni(η2-
C6H4)(PEt3)2] 1, which gives exclusively 1,3-di-tert-butyl-
naphthalene.2 In the first step of this reaction the nickel–carbon
bond is believed to attack the sterically less hindered alkyne
carbon atom to give a nickelaindene intermediate in which the
Experimental
All experiments were performed under an inert atmosphere
with use of standard Schlenk techniques, and all solvents were
dried and degassed prior to use. All reactions involving benzyne
complexes were carried out under argon. The NMR spectra
were recorded on the following Varian instruments: XL-200E
(1H at 200 MHz, 13C at 50.3 MHz, 19F at 188.1 MHz and 31P at
80.96 MHz), Gemini-300 BB (1H at 300 MHz, 13C at 75.4
MHz, 19F at 282.2 MHz and 31P at 121.4 MHz), VXR-300
(1H at 300 MHz and 13C at 75.4 MHz) and VXR-500 (1H at
500 MHz). The chemical shifts (δ) for H and 13C are given in
1
ppm relative to residual signals of the solvent, to external 85%
H3PO4 for 31P and to CFCl3 for 19F. The spectra of all nuclei
1
(except H and 19F ) were 1H or 19F decoupled. Infrared spectra
were measured in solution (KBr cells) on Perkin-Elmer 683 or
2000 FT-IR spectrometers. Mass spectra of the complexes
were obtained on a VG ZAB2-SEQ spectrometer by the fast-
atom bombardment (FAB) technique. Solutions of the
samples were prepared in CH2Cl2 and added to a matrix of
tetraglyme (2,5,8,11,14-pentaoxapentadecane), 3-nitrobenzyl
alcohol or 3-nitrophenyl octyl ether. Mass spectra of the
organic compounds were obtained by the EI method on a VG
O2
R
M
R
M
R
O
O M
H2O
2 R
O
M
R
OH
Scheme 10
F F
F
F
F
F
F
F
F
F
O2
F
F
F
F
PEt3
PEt3
F
F
Ni
+
Ni
O
Ni
Ni
O
O
O
PEt3
PEt3
O
Et3P
PEt3
–
O
23
8
F
F
F
F
F F
O
F
F
F
–
F
F
F
F
F
F
F
Ni
PEt3
O
Ni
PEt3
Ni
PEt3
O
PEt3
– OPEt3
Ni
+
Ni
O
Et3P
O
O
OPEt3
F
F
PEt3
F
F
9a/9b
Scheme 11
3110
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114

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Micromass 7070F or a Fisons Instruments VG AutoSpec
spectrometer.
Preparation of [{Ni(ì-2-OC10H6CF2CF2-3)(PEt3)}2] 10a, 10b
A solution of [Ni(2,3-η-C10H6)(PEt3)2] 3 in hexane (40 cm3),
prepared by reduction of [NiBr(3-BrC10H6-2)(PEt3)2] (0.539 g,
0.92 mmol) with 1% Na/Hg in thf (30 cm3), was stirred under
C2F4 (1 bar) containing oxygen for 16 h. The yellow solid
formed was decanted and dried in vacuo. The 31P NMR
spectrum showed a doublet of doublets at δ 29.05 due to 10b
and a triplet at δ 28.23 due to 10a, the latter predominat-
ing. Recrystallization from CH2Cl2 gave only 10b {198 mg,
51% based on [NiBr(3-BrC10H6-2)(PEt3)2]}; 10a evidently
rearranged to 10b under these conditions. Complex 10b
(Found: C, 52.3; H, 5.0. C36H42F8Ni2O2P2 requires C, 51.6; H,
5.1%): ν max/cmϪ1 (CH2Cl2) 3050w, 2970m, 2940w, 2880w,
1635s, 1605m, 1500m, 1460s, 1340s, 1205s, 1170s, 1045m and
990s; δH (200 MHz, C6D6) 1.05–1.35 (15 H, m), 6.95 [1 H, t,
J(HH) 7.9, H6 or H7], 7.11 [1 H, t, J(HH) 7.7, H7 or H6], 7.25 [1
H, d, J(HH) 8.2, H5 or H8], 7.38 [1 H, d, J(HH) 7.9, H8 or H5],
8.09 [1 H, d, J(HH) 2.6, H1 or H4] and 8.25 (1 H, s, H4 or H1);
δC(75.4 MHz, CD2Cl2) 8.13 (CH3), 13.44 [d, J(CP) 27.4, CH2],
113.36, 123.75, 126.14 (CH), 126.65 [dd, J 10.9, 3.2, C4H],
127.65 (C4a or C8a), 127.82, 128.92 (CH), 136.45 (C8a or C4a),
156.59 [d, J(CP) 7.7, C2], signals due to C3 and the two CF2
groups were not observed; δF (188.2 MHz, CD2Cl2) Ϫ133.81
[dt, J(FF ) 246.0, 8.8], Ϫ102.74 [dddd, J(FF ) 251.8, 22.7, 7.5,
J(FP) 32.0], Ϫ100.00 [dd, J(FF ) 246.1, J 21] and Ϫ93.78 [dt,
J(FF ) 250.2, J 15.3]; δP(80.96 MHz, C6D6) δ 28.96 [dd, J(FP)
31.8, 16.8 Hz]. Complex 10a: δH (200 MHz, C6D6) 1.00–1.50 (15
H, m), 7.00 [1 H, t, J(HH) 7.2, H6 or H7], 7.07 (1 H, s, H1 or H4),
7.25 [1 H, t, J(HH) 7.4, H7 or H6], 7.54 [1 H, d, J(HH) 8.2, H5 or
H8], 7.64 [1 H, d, J(HH) 8.2, H8 or H5] and 8.23 (1 H, s, H4 or
H1); δF (188.2 MHz, C6D6) Ϫ97.21 (br s); δP(80.96 MHz, C6D6)
28.23 [t, J(PF ) 30.8 Hz].
The aryne complexes [Ni(η2-C6H4)L2] (L2 = 2 PEt3 11 or dcpe
22) and [Ni(2,3-η-C10H6)(PEt3)2] 33 were prepared as described
previously; usually they were made in situ and reactions were
carried out directly. Carbon monoxide (99% 13C) was obtained
from Monsanto Research Corporation.
Preparation of [Ni(C6H4CF2CF2)(dcpe)] 7
A solution of [Ni(η2-C6H4)(dcpe)] 2 in toluene (60 cm3) at
Ϫ20 ЊC, prepared by lithium reduction of [NiBr(2-BrC6H4)-
(dcpe)] (1.34 g, 1.87 mmol), was stirred under C2F4 (1 bar) at
room temperature overnight. The dark orange-brown solution
was dried in vacuo and filtered through a silica gel column
(CH2Cl2). Evaporation of the solvent and washing with hexane
yielded complex 7 as a yellow powder (754 mg, 61%) which
could be recrystallized from CH2Cl2 (Found: C, 61.8; H, 7.9.
C34H52F4NiP2 requires C, 62.1; H, 8.0%); ν max/cmϪ1 (CH2Cl2)
2940s, 2860s, 1610w, 1590m, 985s, 955s, 865s and 535m; δH (200
MHz, C6D6) 0.85–1.80 (40 H, m, CH2 of cyclohexyl), 1.80–2.05
(2 H, m, CH2), 2.10–2.40 (4 H, m, CH), 2.50–2.70 (2 H, m,
CH2), 7.10–7.30 (2 H, m, Harom), 7.62 [1 H, t, J(HH) 6.0, H4 or
H5] and 7.82 [1 H, d, J(HH) 7.2, H3 or H6]; δC(75.4 MHz,
CDCl3) 19.68 [dd, J(CP) 21.5, 16.9, CH2], 20.28 [dd, J(CP)
22.0, 17.6, CH2], 26.42, 26.60, 27.50, 27.53, 27.65, 27.86,
28.04 (CH2), 29.60 [d, J(CP) 5.5, CH2], 29.65 [d, J(CP) 3.3,
CH2], 30.93 [d, J(CP) 3.3, CH2], 31.80 [d, J(CP) 5.5, CH2],
35.83 [d, J(CP) 16.5, CH], 35.97 [d, J(CP) 18.6, CH], 122.89,
124.83 (CH), 127.88 [d, J(CP) 4.4, C5H], 139.24 [dd,
J(CP) 9.9, 3.3, C6H], 143.88 [t, J(CF ) 22.0, C2] and 160.70–
162.30 (m, C1); δC(75.4 MHz, CDCl3, 19F-decoupled) 126.20
(C6H4CF2), 143.92 (C2) and 146.89 [dd, J(CP) 92.2, 22.0,
NiCF2]; δF (188.2 MHz, C6D6) Ϫ103.84 [dt, J(FP) 5.7, J(FF )
10.7] and Ϫ93.35 [ddt, J(FP) 32.0, 21.2, J(FF ) 10.6]; δP(80.96
MHz, C6D6) 64.47 [dtt, J(PP) 12.1, J(FP) 32.0, 5.1] and
68.38 [dt, J(PP) 12.1, J(FP) 20.8 Hz]; m/z (FAB) 637
(M Ϫ F ).
Reaction of complex 7 with CO
In a typical experiment, a solution of complex 7 (0.215 g, 0.32
mmol) in thf (30 cm3) was stirred under CO (1 bar) at room
temperature. The course of the reaction was monitored by
NMR (13C, 31P, 19F ) and IR spectroscopy. After 25 h, the acyl
complex [Ni{C(O)C6H4CF2CF2-2}(dcpe)] 14 was the main
species present, although there were traces of 7 and some
2,2,3,3-tetrafluoroindanone 15 had already formed. After 49 h
the reaction mixture contained 14 (major), 15, [Ni(CO)2(dcpe)]
(δP 64.0) and [Ni(dcpe)2] (δP 47.4); no starting material was
observed. When a sample of this reaction mixture was stirred
for 16 h under nitrogen the amount of acyl complex 14 had
decreased and the starting complex 7 had reformed, as shown
by 31P NMR spectroscopy. After 97 h all these compounds were
still present, but the indanone 15 had become the major prod-
uct. The 13C-labelled compounds 14a and 15a were generated
similarly.
In another experiment, a solution of complex 7 (0.183 g, 0.28
mmol) in thf (20 cm3) was stirred at 50 ЊC under CO (3 bar)
containing air. Monitoring showed rapid formation of inter-
mediate 14 and of [Ni(CO)2(dcpe)]. After 5 d the reaction was
complete, as shown by 19F NMR spectroscopy, which showed
Preparation of [Ni(C6H4CF2CF2)(PEt3)2] 8
A solution of [Ni(η2-C6H4)(PEt3)2] 1 in hexane (20 cm3), pre-
pared by reduction of [NiBr(2-BrC6H4)(PEt3)2] (1.02 g, 1.92
mmol) with lithium, was cooled to Ϫ78 ЊC and stirred for 16 h
under dry C2F4 (1 bar) while being allowed to warm up to room
temperature. The resulting suspension was decanted and the
residue washed with hexane to give complex 8 as a yellow solid
{750 mg, 83% based on [NiBr(2-BrC6H4)(PEt3)2]}. δH (200
MHz, C6D6) 0.77–1.10 (18 H, m, CH3), 1.10–1.27 (6 H, m,
CH2), 1.42–1.58 (6 H, m, CH2), 7.04–7.08 (2 H, m, H4,5), 7.36 (1
H, br s, H3 or H6) and 7.61 [1 H, br d, J(HH) 6.0, H6 or H3];
δC(75.4 MHz, C6D6) 8.17, 8.26 (CH3), 16.32 [d, J(CP) 19.8,
CH2], 17.67 [d, J(CP) 18.6, CH2], 122.67, 124.42, 136.76, 136.91
(CH), 143.41 [t, J(CP) 21.9, C1] and 162.70–164.20 (m, C2); δF -
(188.2 MHz, C6D6) Ϫ105.24 (br s) and Ϫ94.58 (m); δP(80.96
MHz, C6D6) 7.75 [dtt, J(PP) 22.3, J(FP) 35.1, 4.9] and 11.48
(apparent q, J 22.9 Hz).
the presence of [Ni{OC(O)C6H4CF2CF2-2}(dcpe)] 16 and
2,2,3,3-tetrafluoroindanone 15 in a 2:1 ratio; 31P NMR spec-
troscopy showed that there was some [Ni(dcpe)2]. The com-
pounds were difficult to separate as they seemed to react with
the chromatography materials. Compound 15 could be
extracted with hexane as a sticky solid (20 mg, 35%). Complex
16 was isolated as a yellow solid by preparative TLC (silica gel,
hexane–acetone 1:1), but some decomposition occurred. The
yield was 75 mg (38%). Single crystals of 16 suitable for X-ray
analysis were obtained from acetone–diethyl ether. The 13C-
labelled carboxylate complex 16a was generated similarly from
Reaction of complex 8 with air
In a qualitative NMR experiment, a solution of complex 8
in CD2Cl2 was left in contact with air for 48 h at room
temperature to give a 1:1.3 mixture of the oxo-dimer
[{Ni(µ-OC6H4CF2CF2-2)(PEt3)}2] 9a, having a 31P triplet at δ
28.07 [J(FP) 30.5 Hz] and a broad 19F singlet at δ Ϫ98.65, and
its isomer 9b. After filtration through silica gel only 9b
remained. δF (188.2 MHz, CD2Cl2) Ϫ133.11 [d, J(FF ) 249.9],
Ϫ101.71 [dm, J(FF ) 245.1], Ϫ100.10 [dd, J(FF ) 249.2, J 21.1]
and Ϫ95.36 [dm, J(FF ) 245.8]; δP(80.96 MHz, CD2Cl2) 29.12
[dd, J(FP) 31.2, 15.6 Hz].
13CO. [Ni{C(O)C6H4CF2CF2-2}(dcpe)] 14: ν max/cmϪ1 (thf) 1615
(C᎐O); δ (188.2 MHz, C D –thf) Ϫ102.07 (br s, C H CF ) and
᎐
F
6
6
6
4
2
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114
3111

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Ϫ94.72 [br tt, J(FP) 33.0, J(FF ) 8.9, NiCF2]; δP(80.96 MHz,
C6D6–thf) 56.77 [t, J(FP) 29.5] and 58.83 [t, J(FP) 37.1 Hz].
δH (200 MHz, CDCl3) 3.97 (3 H, s, OCH3), 3.99 (3 H, s, OCH3),
7.55–7.72 (3 H, m) and 8.09–8.14 (1 H, m); δF (188.2 MHz,
CDCl3) Ϫ143.61 [d, J(FF ) 19.0] and Ϫ143.11 [d, J(FF ) 19.0].
Compound 20: δH (200 MHz, CDCl3) 3.89 (3 H, s, OCH3), 3.97
(3 H, s, OCH3) and 7.20–7.85 (4 H, m, Harom); δF (188.2 MHz,
CDCl3) Ϫ124.72 (br s) and Ϫ120.65 (br s); m/z (C14H10F4O4) 318
(Mϩ, 18), 286 (64), 249 (100), 190 (22), 162 (47) and 150 (28%).
Complex 14a: ν max/cmϪ1 (thf) 1570 (C᎐O); δ (75.4 MHz, C D –
᎐
C
6
6
thf) 256.56 [ddt, J(CP) 75.8, 17.7, J(CF ) 5.5, CO]; δF (188.2
MHz, C6D6–thf) Ϫ103.39 (br s) and Ϫ96.11 [dtt, J(CF ), 5.5,
J(FP) 33.0, J(FF ) 8.8]; δP(80.96 MHz, C6D6–thf) 56.79 [dt,
J(CP) 18.6, J(FP) 30.2] and 58.85 [dt, J(CP) 75.7, J(FP) 37.9
Hz]. Compound 15: ν max/cmϪ1 (CHCl3) 2963w, 2873w, 1759s
(CO), 1608w, 1303m, 1292m, 1261m, 1200w, 1158m, 1125s,
1034m, 960m, 891m, 808w and 768w; δH (300 MHz, CDCl3)
7.80–8.05 (4 H, m); δC(75.4 MHz, CDCl3) 124.86, 124.88,
134.07 (CH), 134.90 (C7), 138.32 (CH), the multiplets expected
for CO, C2F2, C3F2 and C4 were not visible; δF (188.2 MHz,
CDCl3) Ϫ126.48 (s) and Ϫ108.60 (s). Compound 15a: δC(50.3
MHz, CDCl3) 184.93 [t, J(CF ) 25.3, CO]; δF (188.2 MHz, C6D6)
Ϫ127.20 [dt, J(CF ) 25.1, J(FF ) 3.2, C2F2] and Ϫ109.2 [t, J(FF )
3.1 Hz, C3F2]; m/z (high resolution) 205.022 389; C813CF4O
requires 205.022 040. Complex 16: ν max/cmϪ1 (CH2Cl2) 2940vs,
Reaction of complex 8 with tert-butylacetylene
A solution of crude complex 8 (0.7 mmol) in thf (10 cm3) at
Ϫ50 ЊC was treated with tert-butylacetylene (0.25 cm3, 2 mmol)
and the mixture allowed to warm up to room temperature over
1 h. The 31P NMR spectrum of the solution showed that 8 had
completely disappeared. The solution was filtered through silica
gel and the solvent evaporated. The residue was purified by
preparative TLC (hexane) to give 4-tert-butyl-1,2-difluoro-
naphthalene 21 (58 mg, 38%): δH (500 MHz, CDCl3) 1.58 (9 H,
s, But), 7.32 [1 H, dd, J(HF ) 13.3, 8.2, H3], 7.41 (1 H, m, H6),
7.46 (1 H, m, H7), 8.07 (1 H, m, H8) and 8.34 (1 H, m, H5); this
spectrum was simulated by LAOCOON as an ABCDMXY
spin system with 3J(F1F2) 20.2, 3J(F2H3) 13.2, 3J(H5H6) 8.6,
3J(H6H7) 6.9, 3J(H7H8) 8.5, 4J(F1H8) 1.1, 4J(F1H3) 7.9, 4J(H5H7)
2860s, 1630s (C᎐O), 1605m, 1595m, 1570m, 1450m, 1365m,
᎐
1330w, 1290w, 1180m, 1090m, 990m, 870m and 535w; δH (300
MHz, [2H6]acetone) 1.25–2.35 (48 H, m, dcpe), 7.58–7.68 (3 H,
m), 7.83 [1 H, br d, J(HH) 7.1, H6]; δC(75.4 MHz, [2H6]acetone)
17.28 [dd, J(CP) 23.7, 7.9, CH2], 21.71 [dd, J(CP) 30.0, 17.2,
CH2], 26.49, 26.51, 26.58, 26.59, 27.50, 27.62, 27.76, 27.92,
28.12, 28.31, 29.20, 29.40, 29.69, 29.93, 29.96 (CH2 of C6H11),
31.86 [d, J(CP) 2.3, CH2 of C6H11], 33.76 [d, J(CP) 18.2], 36.92
[d, J(CP) 23.2] (CH of C6H11), 126.05 (m, C3H), 129.08 (CH),
129.54 (CH), 130.34 (C6H), 132.65 [t, J(CF ) 23.5, C2], 141.64
[apparent d, J(CP) 63.9, C1] and 172.10 (CO); δF (188.2 MHz,
[2H6]acetone) Ϫ111.79 (br s), Ϫ95.81 [br t, J(FP) 28.2, NiCF2];
δP(80.96 MHz, [2H6]acetone) 63.69 [dtt, J(PP) 39.7, J(FP) 30.9,
6.0] and 77.76 [dt, J(PP) 39.7, J(FP) 23.5 Hz]. Complex 16a:
4
5
5
1.2, J(H6H8) 1.5, J(F1H5) 0.76, J(H5H8) 0.75 and 6J(F2H7)
1.1; the NOE spectrum showed a 24% response of H3 (δ 7.32)
and a 26% response of H5 (δ 8.34) on irradiation of the But
group at δ 1.58; δC(75.4 MHz, CDCl3) 31.72 (CH3), 35.88 (C),
114.55 [d, J(CF ) 21.6, CH], 121.14 [t, J(CF ) 6.6, CH], 124.56
[d, J(CF ) 3.2, CH], 125.75 [d, J(CF ) 2.2, CH], 126.11 [d, J(CF )
13.2, C], 126.82 (CH), 128.83 (C), 142.89 [dd, J(CF ) 249.3,
12.1, CF], 143.92 [t, J(CF ) 5.5, C] and 144.90 [dd, J(CF ) 243.7,
11.0, CF]; δF (282.2 MHz, CDCl3) Ϫ153.25 [ddd, J(FF ) 20.3,
J(FH) 7.9, 1.7] and Ϫ142.41 [dd, J(FF ) 20.3, J(FH) 13.5 Hz];
m/z (C14H14F2) 220 (Mϩ, 33), 205 (100), 188 (25), 177 (67) and
165 (32%).
ν max/cmϪ1 (CH Cl ) 1595m (C᎐O) and 1570m; δ (300 MHz,
᎐
2
2
H
[2H6]acetone) 1.25–2.35 (48 H, m, dcpe), 7.58–7.68 (3 H, m) and
7.83 [1 H, ddt, J(HH) 7.2, J(CH) 3.9, J(FH) 1.0, H6]; δC(75.4
MHz, [2H6]acetone) 130.40 [d, J(CC) 3.2, C6H], 132.61 [t,
J(CF ) 23.5, C2], 140.84 [apparent dd, J(CP) 69.3, J(CC) 4.2 Hz,
C1] and 172.45 (CO); m/z (C3413CH52F4NiO2P2) 701 (Mϩ, 5), 480
(80), 289 (100) and 241 (38%).
Reaction of complex 8 with methyl propiolate
A solution of crude complex 8 (0.7 mmol) in thf (20 cm3) at
Ϫ15 ЊC was treated slowly with a solution of methyl propiolate
(0.178 cm3, 2 mmol) in thf (3 cm3). The solution was allowed
to warm to room temperature over 3 h and the solvent was
evaporated. The 19F NMR spectrum of the crude product
Reaction of complex 8 with CO
A solution of complex 8 in thf (15 cm3) was stirred for 16 h
under CO (1 bar). The solvent was evaporated and the residue
was purified by preparative TLC (hexane–ether 1:1). The only
fluorine-containing compound isolated was 2,2,3,3-tetra-
fluoroindanone 15.
showed the formation of 2-(HCF CF C H CH᎐C(CO Me)-
᎐
2
2
6
4
2
CH᎐CH(CO Me) 22 in an estimated yield of 70%. This com-
᎐
2
pound did not migrate on silica gel and isolation by sublimation
failed. A preparative TLC on alumina (ether–hexane 1:1)
finally yielded 17 mg of 25 (7%). ν max/cmϪ1 (CH2Cl2) 3055w,
2955m, 2845w, 1725vs, 1630w, 1435s, 1290s and 1115s; δH (300
MHz, CDCl3) 3.69 (3 H, s, OMe), 3.87 (3 H, s, OMe), 5.90 [1 H,
tt, J(FH) 54.0, 2.8, CHF2], 6.65 [1 H, d, J(HH) 15.9, Holefin],
Reaction of complex 7 with dmad
A mixture of complex 7 (401 mg, 0.6 mmol) and dmad (5 cm3)
in thf (40 cm3) was refluxed for 48 h. The resulting orange
solution was evaporated to give a deep red oil that contained
7.23 (1 H, m, Harom), 7.28 [1 H, dd, J(HH) 15.9, 0.9, Holefin
]
(becomes a doublet on irradiation of the triplet at δ 8.07), 7.46–
7.59 (2 H, m, Harom), 7.61 [1 H, dd, J(HH) 7.3, 1.9, Harom] and
8.07 [1 H, br t, J(FH) 3.6, Holefin]; δC(75.4 MHz, CDCl3) 51.72,
52.46 (OMe), 110.25 [t, J(CF ) 42.8], 128.23 [t, J(CF ) 7.7, CH],
129.30, 131.36, 131.71 (CH), 133.78 (C), 135.92, 144.07 (CH),
166.21, 167.40 (CO2Me), CHF2 and several quaternary C not
located; δF (282.2 MHz, CDCl3) Ϫ134.22 [dt, J(FH) 54.0, J(FF )
4.4 Hz, CF2H] and Ϫ110.45 (apparent qnt, J 4.0); m/z
(C16H14F4O4) 346 (Mϩ, 20), 315 (25), 287 (100), 255 (64), 244
(32), 213 (47), 177 (42), 149 (51), 71 (61) and 57 (99%).
[Ni{C(CO Me)᎐C(CO Me)C H CF CF -2}(dcpe)] 18 in add-
᎐
2
2
6
4
2
2
ition to polymeric material. All attempts to purify the complex
by TLC or fractional crystallization proved unsuccessful.
δP(80.96 MHz, C6D6) 54.95 [ddt, J(PP) 24.4, J(FP) 29.1, 9.2]
and 63.24 [ddd, J(PP) 24.4, J(FP) 98.9, 3.9 Hz]. These data are
similar to those of the corresponding naphthalene-based
complex.3
Reaction of complex 8 with dmad
Dimethyl acetylenedicarboxylate (0.02 cm3) was added to a
solution of complex 8 (about 30 mg) in C6D6 (0.5 cm3).
Reaction occurred immediately to give a complicated mixture,
as shown by 31P and 19F NMR spectroscopy. Attempted separ-
ation by preparative TLC (CH2Cl2) gave a mixture of 3,4-F2-
1,2-(CO2Me)2C10H4 19 and dihydronaphthalene 3,3,4,4-F4-1,2-
(CO2Me)2C10H4 20, whose structures were assigned tentatively
on the basis of NMR and mass spectroscopy. Compound 19:
X-Ray crystallography of [{Ni(ì-2-OC10H6CF2CF2-3)(PEt3)}2]
10b and [Ni{OC(O)C6H4CF2CF2-2}(dcpe)] 16
Selected crystal data, details of data collection, data process-
ing, structure analysis and structure refinement are in Table 3.
The structure of complex 10b was solved by Patterson
methods (PATTY)43 and was expanded using Fourier tech-
3112
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114

View Article Online
Table 3 Crystal and structure refinement data for [{Ni(µ-2-OC10H6CF2CF2-3)(PEt3)}2] 10b and [Ni{OC(O)C6H4CF2CF2-2}(dcpe)] 16a*
10b
16
Chemical formula
M
C36H42F8Ni2O2P2
838.06
C35H52F4NiO2P2ؒ0.5(C2H5)2O
738.50
Crystal system
Space group (no.)
a/Å
Monoclinic
P21/n (14)
12.429(3)
Triclinic
P1 (2)
9.696(6)
¯
b/Å
c/Å
α/Њ
β/Њ
16.175(3)
20.016(3)
14.068(7)
15.405(9)
100.26(4)
93.21(6)
106.47(2)
γ/Њ
109.16(5)
1938(2)
1.265
U/Å3
3858(1)
1.442
4
Dc/g cmϪ3
Z
2
F(000)
1728
786
Crystal size/mm
0.13 × 0.14 × 0.20
11.28 (Mo-Kα)
Rigaku AFC6S
Mo-Kα
0.28 × 0.16 × 0.20
19.24 (Cu-Kα)
Rigaku AFC6R
Cu-Kα
µ/cmϪ1
Diffractometer
X-Radiation
(graphite monochromated)
ω-Scan width
2θ Limit/Њ
h, k, l Range
Total reflections
1.20 ϩ 0.34 tan θ
45.1
(0, 0, Ϫ24) to (15, 19, 24)
5573
1.40 ϩ 0.30 tan θ
120.6
(Ϫ10, Ϫ16, 0) to (10, 16, 17)
6006
Unique reflections (Rint
)
5290 (0.134)
5759 (0.043)
Used reflections [I > 3σ(I)]
Corrections (transmission factors)
No. parameters
2755
3357
Analytical47 (0.753 to 0.902)
452
Azimuthal scans (0.412 to 1.000)
455
Weighting scheme, w
R, RЈ (used reflections)
Goodness of fit
4Fo /[σ2(Fo ) ϩ (0.002Fo )2]
0.035, 0.024
4Fo /[σ2(Fo ) ϩ (0.013Fo )2]
0.076, 0.092
2
2
2
2
2
2
1.75
0.35, Ϫ0.24
3.01
0.68, Ϫ0.69
ρmax, ρmin/e ÅϪ3
* Details in common: orange, prism; ω–2θ scans; all calculations were performed by use of TEXSAN 46 with neutral atom scattering factors from
Cromer and Waber,48 ∆f and ∆fЈ values from ref. 49 and mass attenuation coefficients from ref. 50; anomalous dispersion effects were included in Fc.51
niques (DIRDIF 92),43 whereas the structure of 16 was solved
10 E. Carmona, M. Paneque, M. L. Poveda, R. D. Rogers and
by direct methods (SIR 92)44 and was expanded using Fourier
J. L. Atwood, Polyhedron, 1984, 3, 317.
11 E. Carmona, M. Paneque and M. L. Poveda, Polyhedron, 1989, 8,
techniques (DIRDIF 94).45 The structure of 16 contains Et2O
285.
as solvation molecule. All non-hydrogen atoms were refined
12 M. A. Bennett, D. C. R. Hockless, M. G. Humphrey, M. Schultz
anisotropically by full-matrix least squares, except for the C
atoms of the minor component of a disordered cyclohexyl
group in 16. Hydrogen atoms were included at calculated pos-
itions (C᎐H 0.95 Å) and held fixed. For 16, Et2O and the minor
disordered components of the cyclohexyl group were refined
without hydrogens. All calculations were performed using the
TEXSAN program.46
and E. Wenger, Organometallics, 1996, 15, 928.
13 E. R. Hamner, R. D. W. Kemmitt and M. A. R. Smith, J. Chem.
Soc., Dalton Trans., 1977, 261.
14 L. Cassidei and O. Sciacovelli, LAOCOON-5 (QCPE Program
no. 458), modified and included in NMRI Software Package,
Version 1.1, New Methods Research, Inc., New York, 1990.
15 C. K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, 1976.
CCDC reference number 186/580.
16 Y.-J. Kim, K. Osakada, A. Takenaka and A. Yamamoto, J. Am.
Chem. Soc., 1990, 112, 1096.
17 E. Carmona, J. M. Marín, P. Palma, M. Paneque and M. L. Poveda,
Inorg. Chem., 1989, 28, 1895.
Acknowledgements
18 R. R. Burch, J. C. Calabrese and S. D. Ittel, Organometallics, 1988,
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19 M. R. Churchill and T. A. O’Brien, J. Chem. Soc. A, 1970, 161.
20 A. Greco, M. Green, S. K. Shakshooki and F. G. A. Stone, Chem.
Commun., 1970, 1374.
Mr. Chris Blake from the Australian National University NMR
centre is gratefully acknowledged for the LAOCOON
simulations.
21 F. G. A. Stone, Pure Appl. Chem., 1972, 30, 551.
22 P. K. Maples, M. Green and F. G. A. Stone, J. Chem. Soc., Dalton
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23 C. A. Tolman and W. C. Seidel, J. Am. Chem. Soc., 1974, 96, 2774.
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C. Krüger, J. Organomet. Chem., 1990, 389, 399.
25 W. Schröder, W. Bonrath and K. R. Pörschke, J. Organomet. Chem.,
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Received 7th April 1997; Paper 7/02375H
3114
J. Chem. Soc., Dalton Trans., 1997, Pages 3105–3114