Reduction of metal-stabilized α-CF3-carbenium ion complexes under mild conditions: Synthesis, structures, and reactivity

Article abstract of DOI:10.1002/(SICI)1099-0682(200002)2000:2<359::AID-EJIC359>3.0.CO;2-V

Complexed α-CF₃ propargyl alcohols of the general formula [(M₂L₆)(μ-η²,η²-RC?CCH(CF₃)(OH))] were prepared with M₂L₆ = CO₂(CO)₆, R = CH₃

Full text of DOI:10.1002/(SICI)1099-0682(200002)2000:2<359::AID-EJIC359>3.0.CO;2-V

FULL PAPER
Reduction of Metal-Stabilized ␣-CF3-Carbenium Ion Complexes under Mild
Conditions: Synthesis, Structures, and Reactivity
[a]
[a]
[a]
[a]
´
´
´
Michel Gruselle,* Bernard Malezieux, Roman Andres, Hani Amouri,
Jacqueline Vaissermann,[a] and Gagik G. Melikyan[b]
Keywords: Radicals / Carbenium ions / Clusters / Cobalt / Molybdenum
Complexed α-CF3 propargyl alcohols of the general formula
[(M2L6){µ-η2,η2-RCϵCCH(CF3)(OH)}] were prepared with
[{Co(CO)3MoCp(CO)2}{µ-η2,η3-CH3(CH2)4CϵCCH(CF3)}][BF4]
(8) with NaSMe unexpectedly afforded the reduced alkyne
adduct
M2L6 = Co2(CO)6, R = CH3(CH2)4– (1), R = C6H5– (2); M2L6
=
[{Co(CO)3MoCp(CO)2}{µ-η2,η2-CH3(CH2)4CϵCCH2-
Co2(CO)5P(C6H5)3, R = CH3(CH2)4– (3a,b), R = C6H5– (4a,b);
M2L6 = Co2(CO)4dppm, R = C6H5– (5); M2L6 = Co(CO)3-
MoCp(CO)2, R = CH3(CH2)4– (6a,b), R = C6H5– (7a,b). An X-
(CF3)}] (13), along with the alkyne-thioether diastereomers
{Co(CO)3MoCp(CO)2}{µ-η2,η2-CH3(CH2)4CϵCCH(CF3)(SMe)}]
(18a,b). Presumably, all the reduction reactions proceed
ray molecular structure of the propargyl-alcohol complex primarily by the formation of the transient radical species, which
[{Co2(CO)4dppm}{µ-η2,η2-C6H5CϵCCH(CF3)(OH)}] (5) was are subsequently transformed into the reduced alkyne
also determined. The related carbenium ions [(M2L6){µ-η2,η3-
complexes by hydrogen abstraction from the solvent medium.
RCϵCCH(CF3)}][BF4] (8–12) were obtained from the parent Interestingly, in the case of the complexed alcohols
propargyl alcohol complexes by direct protonation with HBF4 ·
Et2O in diethyl ether. These carbenium ions were reduced
[{Co2(CO)5P(C6H5)3}{µ-η2,η2-RCϵCCH(CF3)(OH)}] (3a,b) and
(4a,b), the reduction process occurs in acidic medium in THF/
further by Zn in CH2Cl2 to give the alkyne adducts [(M2L6){µ- CH2Cl2. An extensive study of the electronic and steric factors
η2,η2-RCϵCCH2(CF3)}] (13–17), as confirmed by the X-ray
molecular structure of
CϵCCH2(CF3)}] (17). Treatment of the carbenium ion complex
that influence the stability and reactivity of the carbenium ions
were performed, which allowed us to explain the behavior of the
related radical species in solution during the reduction process.
[(Co2(CO)4dppm){µ-η2,η2-C6H5-
Metal-stabilized carbon electron deficient systems of the
type [(M2L6)(µ-η2,η3-RCϵCCR2)]ϩ have been the focus of
several reviews.[5] The analogous carbon-radical complexes
were also reported.[6] In the latter, coupling reactions were
observed.[7] A synthetic application of this chemistry is the
preparation of cyclic diacetylenic compounds promoted by
recombination of [Co2(CO)6]2 diacetylenic di-radicals.[8]
Pursuing our research investigations in this field we pre-
pared a new class of α-CF3-propargyl alcohol complexes, in
which a dinuclear cluster of the type [Co2(CO)6], [Co2-
(CO)5P(C6H5)3], [Co2(CO)4{P(C6H5)2}2CH2], or heterobi-
metallic [Co(CO)3MoCp(CO)2] is coordinated to the acetyl-
enic unit (ϪCϵCϪ) (Figure 1).
Introduction
Trifluoromethyl propargyl alcohols are easily available,[1]
however their synthetic interest is still limited, due to the
difficulty of preparing the related α-CF3 carbenium ions
prior to nucleophilic addition. Functionalization of the car-
benium ion in the α-position relative to the CF3 group is
therefore a hard task.[2] Furthermore, the CF3 function is a
strong electron-withdrawing group and thus strengthens the
CϪO bond, which prevents the formation of a carbenium
center (CF3ϪCϩ). In addition, the steric effects and elec-
tronic repulsion of the incoming nucleophiles with fluorine
atoms of the α-CF3 group decrease the reaction rate, and
harsh conditions are often required.[3][4] To overcome such
difficulties it is vital to stabilize the carbenium center
(CF3ϪCϩ). This can be achieved by introducing a dinuclear
cluster such as M2L6 ϭ [ϪCo2(CO)6]; ϭ [ϪCp2Mo2(CO)4]
or a mixed dinuclear complex ϭ [ϪCo(CO)3MoCp(CO)2]
to the acetylenic unit of the trifluoromethyl propargyl al-
cohols. A direct metal···Cϩ interaction with carbenium
center therefore occurs, which stabilizes the whole complex
and allows further functionalization to proceed under
mild conditions.
Figure 1. General formula of metal-stabilized carbenium ion
[a]
´
´
Laboratoire de Chimie Inorganique et Materiaux Moleculaires,
´
ESA 7071-CNRS, Universite Pierre et Marie Curie,
4, place Jussieu, case 42, F-75252 Paris cedex 05, France
E-mail: gruselle@ccr.jussieu.fr
In a preliminary communication,[9] we have shown that
it is possible to obtain and isolate α-CF3 methyl- or phenyl-
substituted propargylium ions, when they are stabilized by
[b]
Department of Chemistry, California State University-Nor-
thridge,
18111 Nordhoff Str., Northridge, CA 91330, USA
Eur. J. Inorg. Chem. 2000, 359Ϫ368
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000
1434Ϫ1948/00/0202Ϫ359 $ 17.50ϩ.50/0
359

M. Gruselle et al.
FULL PAPER
˚
an adjacent bimetallic [Co2(CO)6]- or [Co(CO)3MoCp- 2.473 A conforms with previous literature values for a sin-
(CO)2]-acetylenic cluster. Through out the paper we will use gle CoϪCo bond.[11] The coordination geometry of each
the abbreviations [Co2] for [Co2(CO)6], and [Co,Mo] for Co center is a distorted octahedron occupied by the acety-
[Co(CO)3MoCp(CO)2].
lene carbons, two carbonly ligands and a coordinated phos-
In this paper we describe the synthesis of bimetallic [Co2] phane ligand of the bridged dppm unit.
and [Co,Mo] complexed acetylenic α-CF3 alcohols and de-
scribe their ability to give carbenium ions in acidic medium.
The capacity of these ions to be reduced, either directly
from the complexed propargyl alcohols or starting from the
related metal-stabilized carbenium ions, has also been inves-
tigated.
Results and Discussion
Synthesis, Structure, and Characterization of ␣-CF3-
Propargyl Alcohol Complexes [(M2L6){µ-η2,η2-
RCϵCCH(CF3)(OH)}]
The α-CF3 propargyl alcohols were synthesized by treat-
ment of the ethyltrifluoroacetate with the appropriate lithi-
ated acetylenic compound: RCϵCLi [R ϭ CH3(CH2)4Ϫ;
C6H5Ϫ]. The obtained ketones were then reduced by
NaBH4 in alcoholic medium, and the resulting alcohols are
subsequently complexed by Co2(CO)8 leading to the alkyne
complexes
[{Co2(CO)6}{µ-η2,η2-RCϵCC(OH)(CF3)H}]
{R ϭ CH3(CH2)4-(1); R ϭ C6H5-(2)} according to
Scheme 1.
Figure 2. X-ray molecular structure of [{Co2(CO)4dppm}{µ-η2,η2-
C6H5CϵCCH(CF3)(OH)}] (5) with atom numbering system
˚
Table 1. Selected bond lengths [A] and angles [°] for complex 5
Co(1)ϪCo(2)
Co(1)ϪC(3)
Co(1)ϪC(4)
Co(2)ϪC(4)
2.473(1) Co(1)ϪP(1)
1.942(6) Co(2)ϪP(2)
1.974(7) Co(2)ϪC(3)
1.970(6) C(3)ϪC(4)
2.227(2)
2.222(2)
1.947(6)
1.357(9)
Co(1)ϪC(4)ϪCo(2) 77.7(2)
C(3)ϪC(4)ϪC(41)
Co(1)ϪC(3)ϪCo(2) 79.0(2)
141.5(6) C(2)ϪC(3)ϪC(4)
126.6(7)
Furthermore, the α-CF3-alcohol complexes 3a, b and 4a,
b exist as a pair of diastereomers (Scheme 2). Starting from
the [Co2]-complexed alcohols 1؊2, the substitution of the
metallic vertex [Co(CO)3] by the isolobal [MoCp(CO)2]
leads to the hetero-bimetallic [Co,Mo]-complexed al-
Scheme 1. Preparation of complexed [Co2(CO)6]propargyl alcohols
Substitution of a carbonyl ligand of complexes 1؊2 by cohols[12] obtained also as two diastereomers 6a, b and 7a,
either a monophosphane [P(C6H5)3] or a chelating phos- b, respectively. The complexed alcohols 1؊7 thus obtained
phane such as dppm ϭ [{P(C6H5)2}2CH2] using standard have the α-CF3 substituent on the carbon atom bearing the
methods[10] leads to the phosphaneϪ[Co2]-complexed al- hydroxyl function, while the C-4 acetylenic carbon is either
cohols 3a, 3b, 4a, 4b, and 5. All compounds were com- substituted by an alkyl or an aryl substituent.
pletely characterized further, and the X-ray molecular
Mayr et al.[13] recently reported that alkyl or aryl sub-
structure of [{Co2(CO)4dppm}{µ-η2,η2-C6H5CϵCCH- stituents at C-4 do not affect the electronic density of the
(CF3)(OH)}] (5) was determined. This compound crys- cluster unit, and consequently do not affect the electrophil-
tallizes in the monoclinic unit cell, space group P21/n. The icity of the corresponding [Co2]Ϫcarbenium ions. The
bonding and molecular geometry of 5 are shown in a C- major differences among these complexed propargyl al-
[24] diagram in Figure 2. Crystallographic data and cohols (1Ϫ7) therefore reside in the electronic nature of the
parameters for 5 are given in Table 4, selected bond lengths bimetallic moieties coordinated to the acetylenic function.
and angles are listed in Table 1. Complex 5 consists of a
It is well established that a cluster unit, or its electron
tetrahedral Co2C2 core with ϪCϵCϪ bond of the acetylene donating ability, alleviates the positive charge of the adjac-
ϩ
unit in a perpendicular orientation at a almost 90° angle ent α-carbenium center. It was previously shown by pKR
relative to CoϪCo bond. The metal-metal bond length of measurements that the [MoCp(CO)2] vertex is much more
360
Eur. J. Inorg. Chem. 2000, 359Ϫ368

Reduction of Metal-Stabilized α-CF3-Carbenium Ion Complexes
FULL PAPER
Scheme 2. Preparation of heterobimetallic [CoϪMo]- and [Co2]-phosphane propargyl aclohols
efficient as an electron donating group than the [Co2(CO)6] solution towards reduction. The results are presented in the
unit[14][15] Consequently, the [Mo2] or [Co,Mo] are much next section.
more stable and less reactive than the [Co2]-complexed car-
benium ions. Due to their low reactivity several X-ray struc-
tures of [Mo2]- or [Co,Mo]-stabilized carbenium ions were
reported in the literature.[1][5] However, very recently an X-
ray structure of a [Co2]Ϫcarbenium ion complex has been
described. In this particular example, the carbenium center
is flanked by two [Co2] cluster units.[16] Spectroscopic re-
1
sults based on H- and 13C-NMR analysis and MO calcu-
lations on these metal-stabilized carbenium ions have
shown that the electronic transfer occurs from the ligand
to the carbon-deficient electronic center through the metal
atom.[17] For instance, substituting a carbonyl ligand by a
monophosphane or a diphosphane ligand has the dramatic
effect of increasing the electronic density of the cluster core.
This electronic density change is reflected on the νCO ab-
sorptions, which shift to low frequency.[18] Such behavior is
illustrated by complex [{Co2(CO)6}{µ-η2,η2-CH3(CH2)4-
CϵCCH(CF3)(OH)}] (1), which shows three νCO bands at
2097, 2057, and 2029 cmϪ1. The related monophosphane
Figure 3. Schematic drawing showing two opposite interactions at
the cabenium center: (a) metal-stabilized effect; (b) CF3-distabiliza-
tion attactive effect
Synthesis and Reduction of the Metal-Stabilized
␣-CF3-Propargyl Carbenium Ion Complexes [(M2L6)-
{µ-η2,η3-RCϵCCH(CF3)}][BF4]
complex
[{Co2(CO)5P(C6H5)3}{µ-η2,η2-CH3(CH2)2-
CϵCCH(CF3)(OH)}] (3) exhibits νCO absorptions at 2063,
2015, 2005, 1987, and 1962 cmϪ1 (see Table 4). These results
Treatment of the propargyl alcohol complexes
are in accord with those reported by Mayr et al,[13] which [{Co2(CO)6}{µ-η2,η2-RCϵCC(OH)(CF3)H}] (1؊2) by
show
that
the
carbenium
ion
complex HBF4 · Et2O in ether did not afford any precipitate, as ex-
[{Co2(CO)5P(C6H5)3}{µ-η2,η3-HCϵCCH(C6H5)}]ϩ is less pected for the formation of the related carbenium ion salts.
electrophilic than the parent carbenium ion [Co2(CO)6{µ- In contrast, the complexed alcohols 3؊7 gave, under the
η2,η3-HCϵCCH(C6H5)}]ϩ. In summary, based on the lit- same experimental conditions, the corresponding carben-
erature data and our own experiments, we have classified ium ions 8, 9, 10, 11, and 12, respectively (Scheme 3). These
the electron density on the cluster moieties of these α-CF3- results demonstrate that the electron donating effect of the
propargyl alcohols, in decreasing order as follows: [Co,Mo] [Co2] cluster in Complexes (1؊2) is not sufficient to over-
> [Co2P2] > [Co2P] > [Co2]. As for carbenium ion com- come the α-CF3 withdrawing effect. The νCO frequencies in
plexes, it is noteworthy to remark that the carbenium center the starting alcohols and their corresponding carbenium
C-2 will be stabilized by the cluster unit, but to a different ions are listed in Table 3.
extent depending on the scale shown above. This should
Furthermore, we noticed that protonation of the [Co2P]
also overcome the withdrawing effect exerted by the α-CF3 complexed alcohols 3a, b and 4a, b by HBF4 · Et2O in a
group. These two opposing effects (Figure 3) were examined CH2Cl2/THF readily afforded the reduced complexes 15
by monitoring the reactivity of these carbenium ions in and 16, but not the related carbenium ion complexes
Eur. J. Inorg. Chem. 2000, 359Ϫ368
361

M. Gruselle et al.
FULL PAPER
(Scheme 4). In the previous reaction the THF plays the role
of the reducing agent, by acting as a mono-electron donor,
as was previously reported.[19] Surprisingly, complexes 1؊2,
were not reduced using CH2Cl2/THF as a solvent.
Figure 4. X-ray molecular structure of [{Co2(CO)4dppm}{µ-η2,η2-
C6H5CϵCCH2(CF3)}] (17) with atom numbering system
Scheme 3. Synthesis of the metal-stabilized carbenium ions (8Ϫ12).
˚
Table 2. Selected bond lengths [A] and angles [°] for complex 17
It is also interesting to note that under the same exper-
imental conditions the propargyl alcohols 5؊7 afforded the
carbenium ions 8؊9 and 12, therefore these compounds are
very stable and cannot be reduced by the CH2Cl2/THF sys-
tem. Carbenium ions 8؊9 and 12 can readily be reduced,
however, by using Zn/CH2Cl2 as reducing agent leading to
compounds 13؊14 and 17 (Scheme 5). The structures of
these compounds were all identified by spectroscopic meth-
ods and elemental analysis (see Experimental Section), fur-
thermore, the X-ray molecular structure of compound 17
was determined. The compound crystallizes with one mol-
ecule of acetone in the triclinic unit cell, space group P1.
The bonding and molecular geometry of 17 are shown in a
C[24] diagram in Figure 4. Crystallographic data
and parameters for 17 are given in Table 4, selected bond
lengths and angles are listed in Table 2. Complex 17 dis-
plays a tetrahedral Co2C2 core with -CϵC- bond of the
acetylene unit in a perpendicular orientation at a almost
90° angle relative to CoϪCo bond. The metal-metal bond
Co(1)ϪCo(2)
Co(1)ϪC(3)
Co(1)ϪC(4)
Co(2)ϪC(4)
Co(1)ϪC(4)ϪCo(2) 79.1(2)
C(3)ϪC(4)ϪC(41)
2.4876(7) Co(1)ϪP(1)
1.950(4) Co(2)ϪP(2)
1.939(4) Co(2)ϪC(3)
1.967(4) C(3)ϪC(4)
2.227(1)
2.225(2)
1.934(4)
1.341(6)
Co(1)ϪC(3)ϪCo(2) 79.6(2)
135.5(4) C(2)ϪC(3)ϪC(4)
135.1(4)
Table 3. Comparison of ν(CO) (cmϪ1) frequencies between the
complexed alcohols and their corresponding carbenium ions
Alcohol
ν(CO) [cmϪ1
]
Cations ν(CO) [cmϪ1
]
[Co2]-(1)
[Co2]-(2)
[Co2P]-(3)
2097, 2057, 2029
2048, 2050, 2020
2063, 2015, 2005,
1987, 1967
unstable, not isolated
unstable, not isolated
2104, 2065, 2055,
2006, 1989
2108, 2072, 2005
2138, 2063, 2005
8
9
[Co2P]-(4)
2068, 2018
[Co2P2]-(5) 2066, 2029, 2001, 10
1974
[Co,Mo]-(6) 2051, 2001, 1984, 11
1942
[Co,Mo]-(7) 2057, 2002, 1949 12
2123, 2071, 2022, 1973
2090, 2065, 2004, 1978
˚
length is 2.4876 A, slightly longer than that of complex 5.
The coordination geometry of each Co center is a dis-
torted octahedron, occupied by the acetylene carbons, two
carbonly ligands, and a coordinated phosphane ligand of
the bridged dppm unit. Overall, the structure of 17 looks
very similar to that of the parent molecule, 5, and confirms
its reduction since the hydroxyl group is now substituted by
a hydrogen atom.
At this stage a few brief comments are required, since,
according to our results, formation of a Co-complexed pro-
pargyl radical is only possible providing its related carben-
ium ion can be formed. This explains why the alcohol com-
plexes 1؊2 cannot be reduced by the THF/CH2Cl2 system.
Scheme 4. Reduction of α-CF3-propargyl alcohol complexes (3Ϫ4)
On the other hand, if the carbenium ion complex is strongly using THF/CH2Cl2 in acidic medium
362 Eur. J. Inorg. Chem. 2000, 359Ϫ368

Reduction of Metal-Stabilized α-CF3-Carbenium Ion Complexes
FULL PAPER
Scheme 5. Reduction of the metal-stabilized carbenium ions (8, 9,
and 12) by Zn in CH2Cl2
Scheme 7. Possible reactions of carbon-centered radicals
Another important feature of this chemistry was
demonstrated when the carbenium ion complex
[{Co(CO)3MoCp(CO)2}{µ-η2,η3-CH3(CH2)4CϵCCH-
(CF3)}][BF4] (8) was treated by NaSMe to give two com-
pounds in 1:1 ratio. These compounds were identified,
respectively, as the reduced compound [{Co(CO)3-
MoCp(CO)2}{µ-η2,η2-CH3(CH2)4CϵCCH(CF3)H}] (13)
and the substituted thio-ether complexes [{Co(CO)3-
MoCp(CO)2}{µ-η2,η2-CH3(CH2)4CϵCCH(CF3)(SMe)}]-
(18a and b) obtained as a pair of diastereomers. These re-
sults illustrate that the reaction between the isolated
[Co,Mo] stabilized carbenium ion 9 and the methyl thiolato
anion proceed through a radical pathway, whereby the tran-
sient radical pair species can either recombine in the solvent
cage to give coupling reaction[21] as illustrated by formation
of 18a, b or, after diffusion from the solvent cage, would
abstract a hydrogen atom from the solvent to afford the
reduced alkyne adduct 13 (Scheme 8).
stabilized by the bimetallic cluster, then the mono-electronic
transfer from THF to the deficient electronic center is not
possible, as shown by the alcohol complexes 5؊7, and the
reaction stops at the carbenium ion stage. This hypothesis
is also confirmed by the fact that the complex
[{Mo2Cp2(CO)4}{µ-η2,η2-HCϵCCH(C6H5)(OH)}], which
is isolobal to the compound [{Co2(CO)6}{µ-η2,η2-
HCϵCCH(C6H5)(OH)}], does not lead to coupling prod-
ucts. Finally, Co-stabilized carbenium ion exhibiting a sta-
bility between the two previous examples can be reduced by
mono-electron transfer from THF to give the reduced com-
pounds.
We would also like to outline that by either using the
THF/CH2Cl2 system or by the action of Zn/CH2Cl2, our α-
CF3-propargyl alcohol complexes [{Co2(CO)4L2}{µ-η2,η2-
RCϵCC(OH)(CF3)H}] (3؊7) gave exclusively the re-
duction products, and never the coupling reaction products,
which
is
the
major
product
observed
with
[{Co2(CO)6}{HCϵCCH(C6H5)(OH)}] (Scheme 6).[19]
Conclusion
Co-complexed propargyl radicals may be formed during
the reduction of α-CF3 complexed acetylenic alcohols in
acidic medium providing that their related carbenium ions
are formed and are slightly stabilized. The stability of these
carbenium ions depends on the electron donor ability of the
bimetallic cluster. Our α-CF3-complexed carbenium ions
system seems to offer a new insight into, and the compre-
Scheme 6. Coupling reaction observed for a [CO2]-complexed ace-
tylenic alcohol in acidic medium
Generally, in carbon-centered radical reactions, the com- hension of the factors that allow certain cobalt-stabilized
petition between coupling reactions, dismutation and ab- carbenium ions to undergo one electron reduction process
straction of a hydrogen from the solvent, is a well docu- rather than a substitution reaction. The present study shows
mented area.[20](Scheme 7). For instance, primary carbon that three classes of propargyl alcohol complexes can be
centered radical next to a hydrogen atom in the β position distinguished. These classes could be defined as follows:
favors the dismutation reaction over the other reactions. In- class (a) Ϫ the parent alcohol complexes [{Co2(CO)6}{µ-
creasing the size of the substituents at the radical center η2,η2-RCϵCCH(CF3)(OH)}] (1؊2) cannot be reduced by
favors the abstraction of a hydrogen from the solvent rela- THF/CH2Cl2 in acidic medium because the related [Co2]-
tive to recombination and dismutation. In our propargyl carbenium ions cannot be formed, class (b) Ϫ weakly stabil-
alcohol compounds, the presence of a CF3 group in the ized carbenium ions such as [Co2P] complexes 10 and 11
alpha position to the carbon centered radical would impede are easily reduced in acidic medium by THF/CH2Cl2, and
the coupling reaction, due to electron repulsion, and hence class (c) Ϫ stable carbenium ions such as complexes 8, 9,
abstraction of a proton from the solvent becomes the and 12 can only be reduced when a strong reducing agent
major reaction.
is used.
Eur. J. Inorg. Chem. 2000, 359Ϫ368
363

M. Gruselle et al.
FULL PAPER
Scheme 8. Abstraction and coupling reactions occurring from a radical pair process
tane then pentane/ether, 10:1) leads to a dark red oil in 50% yield
(5.1 g). Ϫ 1H NMR (CDCl3): δ ϭ 5.12 (dq, J ϭ 14.0 Hz, J ϭ
7.2 Hz, 1 H, 2-H), 5.81 (t, J ϭ 8.2 Hz, 2 H, 5-H), 2.53 (d, J ϭ
7.2 Hz, 1 H, OH), 1.62 (m, 2 H, 6-H), 1.43 (m, 4 H, 7,8-H), 0.93
(t, J ϭ 7.2 Hz, 3 H, 9-H). Ϫ 13C NMR (CDCl3): δ ϭ 198.6 (CO),
123.2 (q, J ϭ 282.0 Hz, C-1), 100.1 (C-3), 86.1 (C-4), 70.9 (q, J ϭ
33.0 Hz, C-2), 32.9 (C-5), 31.3 (C-6), 31.0 (C-7), 22.0 (C-8), 13.5
(C-9). Ϫ 19F NMR (CDCl3): δ ϭ Ϫ75.9 (d, J ϭ 6.1 Hz). Ϫ IR
ν(CO): ν˜ ϭ 2095, 2057, 2029 cmϪ1. Ϫ C15H13Co2F3O7 calcd. C
37.52, H 2.73; found C 37.70, H 2.81.
Experimental Section
General Methods: All reactions were carried out under an atmos-
phere of dry argon. Solvents were dried and distilled using standard
techniques. Diethyl ether and THF were distilled from sodium
benzophenone ketyl, dichloromethane and acetonitrile from so-
dium hydride, pentane was treated by sulfuric acid and distilled on
sodium. Ethylrifluoroacetate, heptyne triphenylphosphane, Bis(di-
phenylphosphanyl)methane, Mo2Cp2(CO)6, Co2(CO)8, HBF4/
Et2O, aqueous 40% HBF4, CD2Cl2, CD3Cl, [D6]acetone were used
as purchased. Ϫ IR spectra were recorded on a Bio-rad FTS 165
spectrometer from KBr disks. All absorptions are expressed in wave
[{Co2(CO)6}-{µ-η2,η2-(1,1,1-trifluoro-4-phenylbut-3-yne-2-ol)] (2):
1
numbers (cmϪ1). Ϫ H-, 13C-, 19F and 31P-NMR spectra were re-
The same synthetic procedure was used for the preparation of com-
1
pound (2) as was used for (1). Ϫ H NMR (CDCl3): δ ϭ 7.36 (m,
corded on a Bruker AM instrument, using standard programs for
proton (299.MHz), carbon (75 MHz), fluoride (282 MHz) and
phosphorus (124 MHz) spectra. NMR chemical shifts are reported
in δ (ppm) relative to TMS (1H, 13C), CFCl3 (19F) or 85% H3PO4
(31P); Data (13C, 31P) are proton decoupled. Ϫ Elemental analyses
3 H, C6H5), 5.57 (m, 2 H, C6H5), 5.37 (dq, J ϭ 13.5 Hz, J ϭ 6.1 Hz,
1 H, 2-H), 2.86 (d, J ϭ 6.1 Hz, 1 H, OH). Ϫ 13C NMR (CDCl3):
δ ϭ 198.3 (CO), 137.2, 129.5, 128.9, and 128.2 (C6H5), 124.1 (q,
J ϭ 283.0 Hz, C-1), 92.8 (C-3), 85.6 (C-4), 71.3 (q, J ϭ 31.9 Hz).
Ϫ
19F NMR (CDCl3): δ ϭ Ϫ76.58 (d, J ϭ 6.1 Hz). Ϫ IR ν(CO):
´
´
were performed by: “Centre regional de microanalyse-Universite
Pierre et Marie Curie”.
ν˜ ϭ 2089, 2050, 2020 cmϪ1. Ϫ C16H7Co2F3O7 calcd: C 39.54,H
1.45; found C 40.41, H 1.65.
Throughout the experimental section the carbon numbering system
for the α-CF3-propargyl alcohol complexes is shown on this dia-
gram.
[{Co2(CO)5P(C6H5)3}-µ-η2,η2-(1,1,1-trifluoronon-3-yne-2-ol)] (3a,
3b): To 0.58 g of (1) (1.21 mmol) in THF (15 mL) was added
P(C6H5)3 (0.40 g, 1.52 mmol) in THF (35 mL) and 2.3 mL of a
1  solution of sodium/benzophenone in THF. The reaction was
monitored by TLC (silica gel, eluent pentane/ether 4:1). The reac-
tion was left for one hour at room temperature, then the mixture
was purified by flash chromatography, giving the two dia-
stereomers, which were separated in the order of increasing polarity
(3a) then (3b), as red oils, 0.35 g and 0.06 g (40% and 7% yield,
respectively).
Synthesis of [{Co2(CO)6}-µ,η2,η2-(1,1,1-trifluoronon-3-yne-2-ol)]
(1): To 1-heptyne (2.9 g, 3·10Ϫ2 mol) in THF (40 mL) was added
dropwise at 0°C, butyllithium (11.5 mL of a 2.5  solution). After
stirring 0.5 h, the mixture was cooled to Ϫ50°C and 2.48 g of ethyl-
trifluoroacetate (2·10Ϫ2 mol) were added dropwise. The mixture
was stirred for 1 h and after attaining room temperature, 50 mL of
NH4Cl saturated aqueous solution were added. The organic phase
was extracted by 3 ϫ 25 mL of diethyl ether. The extracts were
dried with MgSO4 and the solvent removed under vacuum; The
colorless oil was dissolved in 30 mL of ethanol and NaBH4 (1.2 g)
was added, progressively. The reaction was monitored by TLC on
silica gel (eluent pentane/ether 5:1). The reaction was complete in
one hour. After addition of water (50 mL) the organic phase was
extracted by 3 ϫ 25 mL of diethyl ether, dried (MgSO4), and the
solvent removed under vacuum to give a colorless oil (4.73 g). To
the obtained oil in 50 mL of diethyl ether was added, at room tem-
perature under argon, dicobalt octacarbonyl (1.2 g, 2.5 .10Ϫ2 mol).
Compound 3a: 1H NMR (CDCl3): δ ϭ 7.56Ϫ7.31 (m, 15 H, C6H5),
3.96 (dq, J ϭ 14 Hz, J ϭ 8.0 Hz, 1 H, 2-H), 2.22 (m, 1 H, 5-H),
1.99 (d, J ϭ 8.0 Hz, 1 H, OH), 1.72 (m, 1 H, 5-H), 1.51 (m, 2 H,
6-H), 1.25 (m, 4 H, 7,8-H), 0.89 (t, J ϭ 7.1 Hz, 3 H, 9-H). Ϫ 13C
NMR (CDCl3): δ ϭ 206.2, 204.8, and 200.9 (CO), 134.3 (d, J ϭ
53.4 Hz, Cipso, C6H5), 133.0 (d, J ϭ 10.1 Hz, Cortho, C6H5), 130.8
(Cpara, C6H5), 129.0 (d, J ϭ 9.5 Hz, Cmeta, C6H5), 123.0 (q, J ϭ
283.5 Hz, C-1), 96.1 (C-3), 92.7 (C-4), 68.9 (q, J ϭ 32.5 Hz, C-2),
31.7, 31.5, and 31.2 (C-5-6-7), 22.7 (C-8), 14.2 (C-9). Ϫ 19F NMR
(CDCl3): δ ϭ Ϫ76.5 (d, J ϭ 6.1 Hz, CF3). Ϫ 31P NMR (CDCl3):
δ ϭ 52.9 (broad). Ϫ IR ν(CO): ν˜ ϭ 2063, 2015, 2005, 1987, and
1962 cmϪ1
.
Compound 3b: 1H NMR (CDCl3): δ ϭ 7.62Ϫ7.55 (m, 15 H, C6H5),
4.13 (dq, J ϭ 14 Hz, J ϭ 7.8 Hz, 1 H, 2-H), 2.36 (m, 1 H, 5-H),
2.04 (m, 1 H, 5-H), 1.86 (d, J ϭ 7.8 Hz, 1 H, OH), 1.51 (m, 2 H,
The reaction was monitored by TLC on silica gel (eluent pentane/ 6-H), 1.29 (m, 4 H, 7,8-H), 0.90 (t, J ϭ 7.1 Hz, 3 H, 9-H). Ϫ 13C
ether, 6:1). The reaction was complete in one hour. After adsorp-
tion of the crude product on silica gel, flash chromatography (pen-
NMR (CDCl3): δ ϭ 206.1Ϫ201.1 (CO), 134.6 (d, J ϭ
39.6 Hz,Cipso), 133.0 (d, J ϭ 10.4 Hz,Cortho), 130.7 (Cpara), 128.9 (d,
Eur. J. Inorg. Chem. 2000, 359Ϫ368
364

Reduction of Metal-Stabilized α-CF3-Carbenium Ion Complexes
FULL PAPER
J ϭ 8.4 Hz,Cmeta), 123.5 (q, J ϭ 234.7 Hz, C-1), 98.8 (C-3), 79.9 1.40 (m, 4 H, 7,8-H), 0.92 (t, J ϭ 6.8 Hz, 3 H, 9-H). Ϫ 13C NMR
(C-4), 71.5 (q, J ϭ 32.0 Hz, C-2), 32.7, 31.9, and 22.7 (C-6-7-8), (CDCl3): δ ϭ 203.0 (CO), 123.5 (q, J ϭ 276.0 Hz, C-1), 105.2 (C-
14.1 (C-9). Ϫ 19F NMR (CDCl3): δ ϭ Ϫ76.7.(d, J ϭ 6.1 Hz, CF3). 3), 90.3 (Cp), 79.8 (C-4), 73.4 (q, J ϭ 32.0 Hz, C-2), 34.9 (C-5),
Ϫ
31P NMR (CDCl3): δ ϭ 51.3.(broad). Ϫ IR ν(CO): ν˜ ϭ 2062, 31.8 (C-6), 30.9 (C-7), 22.2 (C-8), 13.7 (C-9). Ϫ 19F NMR (CDCl3):
2015, 1998, 1963 cmϪ1. Ϫ C32H28Co2F3O6P calcd: C 53.81, H 3.94;
δ ϭ Ϫ75.9 (d, J ϭ 6.1 Hz). Ϫ IR ν(CO): ν˜ ϭ 2051, 2001, 1984,
1942 cmϪ1. Ϫ C19H18CoF3MoO6 calcd: C 41.17, H 3.27; found C
42.99, H 3.12.
found C 55.65, H 4.14.
[{Co2(CO)5P(C6H5)3}-µ-η2,η2-(1,1,1-trifluoro-4-phenylbut-3-yne-2-
ol)] (4a,4b): Compounds (4a) and (4b) were prepared in the same
way described for 3a and 3b, and were isolated in 35% and 25%
yield, respectively.
1
Compound 6b: H NMR (CDCl3): δ ϭ 5.42 (s, 5 H, Cp), 4.94 (dq,
J ϭ 13.0 Hz, J ϭ 7.4 Hz, 1 H, 2-H), 2.96 (m, 2 H, 5-H), 2;19 (d,
J ϭ 7.4 Hz, 1 H, OH), 1.63 (m, 2 H, 6-H), 1.40 (m, 4 H, 7,8-H),
0.91 (t, J ϭ 6.8 Hz, 3 H, 9-H). Ϫ 13C NMR (CDCl3): δ ϭ 202.9
(CO), 124.0 (q, J ϭ 281.0 Hz, C-1), 104.1 (C-3), 90.4 (Cp), 78.6
(C-4), 73.5 (q, J ϭ 31.0 Hz, C-2), 35.1 (C-5), 31.9 (C-6), 30.9 (C-
7), 22.2 (C-8), 13.8 (C-9). Ϫ 19F NMR (CDCl3): δ ϭ Ϫ75.15(d,
J ϭ 6.5 Hz). Ϫ IR ν(CO): ν˜ ϭ 2052, 2003, 1987, and 1940 cmϪ1. Ϫ
C19H18CoF3MoO6 calcd: C 41.17, H 3.27; found C 43.11, H 3.16.
Compound 4a: 1H NMR (CDCl3): δ ϭ 7.41Ϫ7.19 (m, 20 H, C6H5),
3.97 (qui, J ϭ 14.0 Hz, J ϭ 7.8 Hz 1 H, 2-H), 2.03 (d, J ϭ 7.8 Hz,
1 H, OH). Ϫ 13C NMR (CDCl3): δ ϭ 200.5 (CO), 138.8 (Cipso,
C6H5), 133.9 (d, J ϭ 40.3 Hz, Cipso, PC6H5), 133.2 (d, J ϭ 11.6 Hz,
Cortho, PC6H5), 130.7 (Cmeta, PC6H5), 130.4 (C6H5), 128.8 (C6H5),
128.7 (d, J ϭ 9.7 Hz, Cmeta, C6H5), 128.2 (C6H5), 124.0 (q, J ϭ
284.0 Hz, C-1), 85.7 (C-3), 82.4 (C-4), 70.0 (q, J ϭ 31.8 Hz, C-2).
[{Co(CO)3MoCp(CO)2}-µ-η2,η2-(1,1,1-trifluoro-4-phenylbut-3-yne-
2-ol)] (7a, 7b): A slightly modified procedure was used relative to
that of (6a, and 6b). A THF solution of 2 was heated under reflux
for two hours with NaMoCp(CO)3. The diastereomers 7a and 7b
were separated by flash chromatography in the order of increasing
polarity, and were obtained in 35% and 53% yield respectively
(0.2 g) and (0.3 g).
Ϫ
19F NMR (CDCl3): δ ϭ Ϫ75.77(d, J ϭ 6.0 Hz, CF3). Ϫ 31P
NMR (CDCl3): δ ϭ 48.27(broad). Ϫ IR ν(CO): ν˜ ϭ 2068, 2018
cmϪ1
.
Compound 4b: 1H NMR (CDCl3): δ ϭ 7.41Ϫ7.18 (m, 20 H, C6H5),
3.97 (dq, J ϭ 14.0 Hz, J ϭ 7.8 Hz, 1 H, 2-H), 1.88 (d, J ϭ 7.8 Hz,
1 H, OH). Ϫ 13C NMR (CDCl3): δ ϭ 205.9Ϫ203.9Ϫ200.5 (CO),
139.5 (Cipso, C6H5), 133.8 (d, J ϭ 41.1 Hz, Cipso, PC6H5), 133.3
(C6H5), 133.2 (d, J ϭ 10.7 Hz, Cortho, PC6H5), 130.6 (C6H5), 130.5
(d, J ϭ 10.4 Hz, Cmeta, PC6H5), 128.8 (C6H5), 128.7 (d, J ϭ 8.2 Hz,
Cpara, PC6H5), 128.2 (C6H5), 124.6 (q, J ϭ 283 Hz, C-1), 88.1 (C-
3), 79.6 (C-4), 70.3 (q, J ϭ 30.5 Hz, C-2). Ϫ 19F NMR (CDCl3):
δ ϭ Ϫ76.34 (broad). Ϫ 31P NMR (CDCl3): δ ϭ 48.29 (broad). Ϫ
IR ν(CO): ν˜ ϭ 2068, 2018 cmϪ1. Ϫ C33H22Co2F3O6P calcd: C
55.02, H 3.08; found C 56.22, H 3.06.
1
Compound 7a: H NMR (CDCl3): δ ϭ 7.43Ϫ7.33 (m, 5 H, C6H5),
5.46 (s, 5 H, Cp), 5.28 (dq, J ϭ 13.0 Hz, J ϭ 5.7 Hz, 1 H, 2-H),
2.27 (d, J ϭ 5.7 Hz, 1 H, OH). Ϫ 13C NMR (CDCl3): δ ϭ 225.6
(CO), 222.3 (CO), 202.7Ϫ202.3 (CO), 140.4 (Cipso), 129.3 (Cmeta),
128;6 (Cortho), 127.6 (Cpara), 124.7 (q, J ϭ 282.2 Hz,C-1), 98.2 (C-
3), 90.4 (Cp), 88.4 (C-4), 73.4 (q, J ϭ 30.7 Hz, C-2). Ϫ 19F NMR
(CDCl3): δ ϭ Ϫ75.87 (d, J ϭ 5.7 Hz). Ϫ IR ν(CO): ν˜ ϭ 2057, 2002,
1949 cmϪ1
.
1
[{Co2(CO)4dppm}-µ-η2,η2-(1,1,1-trifluoro-4-phenylbut-3-yne-2-ol)]
(5): To a solution of 2 (0.5 g, 1.27 mmol) in 50 mL of hexane was
added dppm (0.5 g, 1.30 mmol). After 0.5 h of reflux, the reaction
was completed. The mixture was purified by flash chromatography
on silica gel, using pentane as eluent then using pentane/ether (1:4).
Complex 5 was obtained in 58% yield (0.66 g). Ϫ 1H NMR
(CDCl3): δ ϭ 7.25Ϫ6.91 (m, 25 H, C6H5), 5.20 (dq, J ϭ 14.0 Hz,
J ϭ 7.5 Hz, 1 H, 2-H), 3.22 (m, 2 H, PCH2P), 2.34 (d, J ϭ 7.5 Hz,
1 H, OH). Ϫ 13C NMR (CDCl3): δ ϭ 205.8, 202.4, and 202.0 (CO),
141.7 (Cipso, C6H5), 130.7, 128.8, and 126.4 (Co,m,p, C6H5), 138.1,
134.1, 132.8, 130.2, 129.7, and 128.3 (m, PC6H5), 124.6 (q, J ϭ
281.4 Hz, C-1), 93.9 (C-4), 91.7 (C-3), 72.4 (q, J ϭ 31.6 Hz, C-2),
34.4 (t,.J ϭ 21.7 Hz, PCH2P). Ϫ 19F NMR (CDCl3): δ ϭ Ϫ76.7
(d, J ϭ 6.0 Hz, CF3). Ϫ 31P NMR (CDCl3): δ ϭ 37.7 (broad). Ϫ
IR ν(CO): ν˜ ϭ 2066, 2029, 2001, 1974 cmϪ1. Ϫ C39H29F3O5P2Co2
calcd: C 57.51, H 3.59; found C 54.37, H 3.54.
Compound 7b: H NMR (CDCl3): δ ϭ 7.43Ϫ7.32 (m, 5 H, C6H5),
5.46 (s, 5 H, Cp), 5.16 (dq, J ϭ 13.0 Hz, J ϭ 5.7 Hz, 1 H, 2-H),
2.34 (d, J ϭ 5.7 Hz, 1 H, OH). Ϫ 13C NMR (CDCl3): δ ϭ 225.4
(CO), 222.8 (CO), 203.0Ϫ201.8 (CO), 140.1 (Cipso), 129.8 (Cmeta),
128.5 (Cortho), 127.9 (Cpara), 124.9 (q, J ϭ 283.0 Hz, C-1), 104.9 (C-
3), 98.8 (C-4), 90.9 (Cp), 73.2 (q, J ϭ 30.3 Hz, C-2). Ϫ 19F NMR
(CDCl3): δ ϭ Ϫ75.89 (d, J ϭ 6.4 Hz). Ϫ IR ν(CO): ν˜ ϭ 2058, 1994,
1948 cmϪ1. Ϫ C20H12CoF3MoO6 calcd: C 42.88, H 2.16; found C
43.90, H 2.54.
[{Co(CO)3MoCp(CO)2}-µ-η2,η3-(1,1,1-trifluoronon-3-yn-2-onium)]
Tetrafluoroborate (8): To a solution of a mixture of (6a) and (6b)
(0.277 g, 0.5 mmol) in 5 mL of ether was added HBF4/Et2O
(0.25 mL). The red solution turns dark with the formation of an
insoluble oil. The reaction was left for 1 h at room temperature,
then the supernatant was removed and the oily material washed
five times with diethyl-ether and finally dried under vacuum for
several hours.
[{Co(CO)3MoCp(CO)2}-µ-η2,η2-(1,1,1-trifluoronon-3-yne-2-ol)]
(6a, 6b): To 0.15 g (0.3 mmol) of 1 in 15 mL THF was added a
solution of NaMoCp(CO)2 in 15 mL THF, prepared from 0.15 g
(0.3 mmol) of Mo2Cp2(CO)6 and 0.014 g ( 0.6 mmol) of Na/1.4 g
Hg [for the detailed preparation of NaMoCp(CO)3 see refer-
ence[12]]. This mixture was stirred for 7 h at room temperature and
monitored by TLC-silica gel using pentane/ether (2:1) as eluent.
After chromatography on silica gel, two products were recovered,
2a and 2b, in the order of increasing polarity. Complexes 2a and
2b were obtained in 58.8% (0.10 g) and 35.3% (0.06 g) yield, respec-
tively.
The carbon numbering system for the α-CF3-carbenium complexes
is illustrated by the following diagram:
1H NMR (CD2Cl2): δ ϭ 5.99 (s, 5 H, Cp), 5.94 (q, J ϭ 7.2 Hz, 1
H, 2-H), 2.98 (m, 2 H, 5-H), 1.73 (m, 2 H, 6-H),1.38 (m, 4 H, 7,8-
H), 0.93 (t, J ϭ 6.6 Hz, 3 H, 9-H). Ϫ 13C NMR (CD3COCD3):
δ ϭ 215.5, 209.2, and 198.2 (CO), 123.5 (q, J ϭ 275.9 Hz, C-1),
1
Compound 6a: H NMR (CDCl3): δ ϭ 5.47 (s, 5 H, Cp), 5.07 (dq,
J ϭ 13 Hz, J ϭ 5.8 Hz, 1 H, 2-H), 2.91 (t, J ϭ 8.0 Hz, 2 H, 5-H), 107.3Ϫ84.7 (C-3,4), 94.0 (q, J ϭ 36.9 Hz, C-2), 93.4 (s, Cp) (C-5),
2;39 (d, J ϭ 5.8 Hz, OH), 1.75 (m, 1 H, 6-H), 1.60 (m, 1 H, 6-H), 35.7 (C-5), 32.6 (C-6), 31.4 (C-7), 22.4 (C-8), 13.9 (C-9). Ϫ 19F
Eur. J. Inorg. Chem. 2000, 359Ϫ368
365

M. Gruselle et al.
FULL PAPER
NMR (CD2Cl2): δ ϭ Ϫ59.2 (broad). Ϫ IR ν(CO): ν˜ ϭ 2104, 2065, Complex 15 was isolated in 30% yield (30 mg). Ϫ 1H NMR
2055, 2006, 1989, and 1947 cmϪ1. Ϫ C19H17BCoF7MoO5 calcd: C
36.57, H 2.74; found C 34.88, H 3.00.
(CDCl3): δ ϭ 7.59Ϫ7.47 (m, 15 H, C6H5), 2.63 (q, J ϭ 10.4 Hz, 2
H, 2-H), 2.20 (m, 1 H, 5-H), 2.04 (m, 1 H, 5-H), 1.60 (m, 1 H, 6-
H), 1.47 (m, 1 H, 6-H), 1.31 (m, 4 H, 7,8-H), 0.91 (t, J ϭ 6.4 Hz,
3 H, 9-H). Ϫ 13C NMR (CDCl3): δ ϭ 206.4, 204.8, and 201.5 (CO),
134.6 (d, J ϭ 40.2 Hz, Cipso, C6H5), 133.1 (d, J ϭ 9.5 Hz, Cortho,
C6H5), 130.7 (s, Cpara, C6H5), 128.9 (d, J ϭ 7.3 Hz, Cmeta, C6H5),
125.9 (q,J ϭ 279 Hz, C-1), 99.5Ϫ78.1 (C-3Ϫ4), 36.0 (q, J ϭ 29 Hz,
C-2), 32.1, 32.0, 31.4 (C-5, C-6, C-7), 22.7 (C-8), 14.2 (C-9). Ϫ 19F
NMR (CDCl3): δ ϭ Ϫ64.80.(t, J ϭ 10.3 Hz, CF3). Ϫ 31P NMR
(CDCl3): δ ϭ 52.84.(broad). Ϫ IR ν(CO): ν˜ ϭ 2059, 2010, 2005,
1997, 1987, and 1963 cmϪ1. Ϫ C32H28Co2F3O5P calcd: C 55.02, H
4.04; found C 52.85 H 4.25.
[{Co(CO)3MoCp(CO)2}-µ-η2,η3-(1,1,1-trifluoro-4-phenylbut-3-yn-
2-onium)] Tetrafluoroborate (9): The same procedure was used as
1
for compound 8. Ϫ H NMR (CD2Cl2): δ ϭ 7.77 (m, 2 H, C6H5),
7.59 (m, 3 H, C6H5), 6.06 (q, J ϭ 6.5 Hz, 1 H, C6H5), 7.43 (m, 2
H, C6H5), 7.35 (m, 3 H, C6H5), 6.06 (q, J ϭ 6.5 Hz, 1 Hz), 6.04
(s, 5 H, CpϪMo). Ϫ IR ν(CO): ν˜ ϭ 2108, 2072, 2005 cmϪ1
.
[{Co2(CO)5P(C6H5)3}-µ-η2,η3-(1,1,1-trifluoronon-3-yne-2-onium)]
Tetrafluoroborate (10): This compound hydrolyses rapidly in solu-
tion, therefore the 1H-NMR spectrum could not be recorded, how-
ever the IR data are reminiscent of a cobaltϪcarbenium ion com-
[{Co2(CO)5P(C6H5)3}-µ-η2,η2-(1,1,1-trifluoro-4-phenylbut-3-yne)]
(16): This compound was also prepared by the two synthetic pro-
cedures outlined above: Method A: Complex 16 was obtained as
red powder in 90% (70 mg). Ϫ Procedure B: Compound 16 was
isolated in a lower yield of 27% (40 mg). Ϫ 1H NMR (CDCl3): δ ϭ
7.36Ϫ7.19 (m, 20 H, C6H5), 2.87 (m, 1 H, 2-H), 2.28 (m, 1 H, 2-
H). Ϫ 13C NMR (CDCl3): δ ϭ 204.0 (CO), 200.7 (CO), 140.0 (Cipso,
plex. Ϫ IR ν(CO): ν˜ ϭ 2138, 2063, and 2005 cmϪ1
.
[{Co2(CO)5P(C6H5)3}-µ-η2,η3-(1,1,1-trifluoro-4-phenylbut-3-yne-2-
onium)] Tetrafluoroborate (11): This compound hydrolyses rapidly
in solution, therefore the 1H-NMR spectrum could not be re-
corded. The infrared data are characteristic of a cobaltϪcarbenium
ion complex. Ϫ IR ν(CO): ν˜ ϭ 2123, 2071, 2022 cmϪ1
.
C6H5), 133.9 (d, Cipso, J ϭ 41.1 Hz, PC6H5), 133.3 (d, Cortho, J
ϭ
[{Co2(CO)4dppm}-µ-η2,η3-(1,1,1-trifluoro-4-phenylbut-3-yne-2-
onium)] Tetrafluoroborate (12): This complex hydrolyses rapidly in
10.5 Hz, PC6H5), 130.5, 129.8, 128.7 (s, Cortho, meta, para), 128.6 (d,
J ϭ 9.8 Hz, Cmeta, PC6H5), 127.0 (s, Cpara, PC6H5), 126.1 (q, J ϭ
281 Hz, C-1), 86.3 (C-3), 90.8 (C-4), 35.2 (q, J ϭ 29.3 Hz, C-2). Ϫ
19F NMR (CDCl3): δ ϭ Ϫ64.75.(t, J ϭ 9.1 Hz, CF3). Ϫ 31P NMR
(CDCl3): δ ϭ 49.53 (broad). Ϫ IR ν(CO): ν˜ ϭ 2065, 2013, and
1983 cmϪ1. ϪC33H22Co2F3O5P calcd: C 56.27, H 3.15; found C
56.34, H 3.21.
1
solution, therefore the H-NMR spectrum could not be recorded.
Ϫ IR ν(CO): ν˜ ϭ 2090, 2065, 2004, 1978 cmϪ1. Ϫ C39H28BCo2-
F7O4P2 calcd: C 52.97, H 3.19; found C 52.52, H 3.85.
[{Co(CO)3MoCp(CO)2}-µ-η2,η2-(1,1,1-trifluoronon-3-yne)]
(13):
The carbenium ion complex 8 (0.11 mmol) was dissolved in CH2Cl2
(20 mL) and an excess of Zn powder (a small spatula portion) was
added, and the reaction stirred for 20 minutes at room temperature
then filtered, and the solvent removed under vacuum. The residue
was purified by chromatography on silica gel using an Et2O/pen-
tane (10:90) mixture. Complex 13 was isolated as red-orange oily
[{Co2(CO)4dppm}-µ-η2,η2-(1,1,1-trifluoro-4-phenylbut-3-yne)] (17):
In a similar manner to that described for complexes 13 and 14,
the reduced compound 17 was obtained from 0.11 mmol of the
carbenium ion complex 12, as a red-orange powder in 90% yield
(79 mg). Ϫ 1H NMR (CDCl3): δ ϭ 7.33Ϫ6.99 (m, 25 H, C6H5),
3.63 (m, 2 H, PCH2P), 3.13 (m, 2 H, 2-H). Ϫ 13C NMR (CDCl3):
δ ϭ 205.9Ϫ202.6 (CO), 142.4 (s, Cipso, C6H5), 138.7, 134.4. and
132.8 (m, C6H5P), 132.7 (s, Cpara, C6H5), 130.7 (m, C6H5P), 130.4
(Cortho, C6H5), 128.6Ϫ128.2 (m, C6H5P), 125.9 (s, Cmeta, C6H5),
126.6 (q, J ϭ 274.5 Hz, C-1), 93.8 (C-4), 88.9 (C-3), 39.1 (q, J ϭ
28.9 Hz, C-2), 34.5 (t, J ϭ 21.8 Hz, PCH2P). Ϫ 19F NMR (CDCl3):
δ ϭ Ϫ64.90.(t, J ϭ 10.49 Hz, CF3). Ϫ 31P NMR (CDCl3): δ ϭ
38.36 (s). Ϫ IR ν(CO): ν˜ ϭ 2027, 1999, 1969, 1959 cmϪ1. Ϫ
C39H29Co2F3O4P2 calcd: C 58.66, H 3.66; found C 56.67, H 3.70.
1
material in 85% yield (65 mg). Ϫ H NMR (CDCl3): δ ϭ 5.37 (s,
5 H, Cp), 3.48 (oct, J ϭ 10.6Ϫ4.3 Hz, 2 H, 2-H), 2.88 (t, J ϭ
8.6 Hz, 2 H, 5-H), 1.61 (m, 2 H, 6-H),1.40 (m, 4 H, 7,8-H), 0.92
(t, J ϭ 7.2 Hz, 3 H, 9-H).
[{Co(CO)3MoCp(CO)2}-µ-η2,η2-(1,1,1-trifluoro-4-phenylbut-3-yne)]
(14): The preparation of this complex is similar to that of com-
pound 13. Thus, starting with 0.11 mmol of the carbenium ion
complex 9 in CH2Cl2, the target compound 14 was isolated as a
red-orange oily material in 80% yield (48 mg). Ϫ 1H NMR
(CD3COCD3): δ ϭ 7.01 (m, 5 H, C6H5), 5.10 (s, 5 H, Cp), 3.37 (q,
J ϭ 9.75 Hz, 2 H, CH2). Ϫ 13C NMR (CDCl3): δ ϭ 233.1, 225.7,
[{Co(CO)3MoCp(CO)2}-µ-η2,η2-(1,1,1-trifluoro-2-(methylthio)non-
3-yne)] (18a, 18b) and [{Mo2Cp2(CO)4}-µ-η2,η3-(prop-2-yn-1-on-
ium)] Tetrafluoroborate (19): A mixture of the two alcohol dia-
stereomers 6a, and b (220 mg, 0.40 mmol) were dissolved in 10 mL
of Et2O. The red solution was protonated by 0.2 mL of
HBF4 · Et2O at room temperature, affording a dark red oily pre-
cipitate. This material was isolated and washed 5 times with Et2O.
CH2Cl2 was then added (10 mL) and NaSMe (30 mg, 0.43 mmol.)
was introduced, and the reaction was left to stir for 10 minutes.
The solvent was removed and the residue was purified by chroma-
tography on silica-gel using Et2O/pentane 10:90 to yield inseparable
mixture of the two diastereoisomer-substituted complexes 18a, and
b (1:1) in 35% yield (82 mg). The reduced complex 19 was obtained
in 35% yield (74 mg).
and 213.0 (CO), 141.2 (Cipso, C6H5), 128.9, 128.5, and 127.1 (Co,m,p
,
C6H5), 126.5 (q, J ϭ 272 Hz, C-1), 91.4 (Cp), 95.5Ϫ90.8 (C-3, C-
4), 39.2 (q, J ϭ 29.3 Hz, C-2). Ϫ 19F NMR (CDCl3): δ ϭ Ϫ64.43
(t, J ϭ 9.8 Hz, CF3). Ϫ IR ν(CO): ν˜ ϭ 2056, 2004, 1993, 1944
cmϪ1. Ϫ Anal. for C20H12CoF3MoO5 calcd: C 44.14, H 2.22; found
C44.26, H2.28.
[{Co2(CO)5P(C6H5)3}-µ-η2,η2-(1,1,1-trifluoronon-3-yne)] (15): This
complex was prepared by two different procedures:
Method A: This synthetic procedure is the same as the one de-
scribed for complexes 13 and 14. Complex 15 was obtained in 60%
yield as red oily material (46 mg).
Method B: The alcohol starting materials 3a, and b (100 mg,
0.142 mmol) were dissolved in 2 mL of CH2Cl2 in the presence of
31 µL of THF. The red solution was treated with HBF4 · Et2O
(58 mL) at Ϫ5°C, and the reaction was left to attain room tempera-
ture. The solvents were removed and the residue was purified by
chromatography on silica gel using Et2O/pentane (10:90) as eluent.
Spectroscopic Data for 18a, and b: 1H NMR (CDCl3): δ ϭ
5.44Ϫ5.40 (s, 5 H, Cp), 4.25 (m, 1 H, 2-H), 2.93 (m, 2 H, 5-H),
2.36Ϫ2.35 (s, 3 H, SCH3), 1.7 (m, 2 H, 5-H), 1.65 (m, 2 H, 6-H),
1.42 (m, 4 H, 7,8-H), 0.92Ϫ0.93 (t, J ϭ 6.3 Hz, 3 H, 9-H). Ϫ IR
ν(CO): ν˜ ϭ 2051, 2000, 1985, 1939 cmϪ1
.
366
Eur. J. Inorg. Chem. 2000, 359Ϫ368

Reduction of Metal-Stabilized α-CF3-Carbenium Ion Complexes
Table 4. Crystal data for compounds 5 and 17
FULL PAPER
Compound 5
Compound 17
Formula
mass
C39H29Co2F3O5P2
C39H29Co2F3O4P2 · C3H6O
814.5
856.5
˚
a [A]
11.756(4)
11.099(5)
11.712(2)
15.575(7)
87.57(3)
86.50(4)
76.26(4)
1962(1)
2
triclinic
P-1
9.8
1.45
˚
b [A]
20.542(4)
˚
c [A]
15.404(5)
α [°]
β [°]
γ [°]
90
96.98(3)
90
3
˚
V [A ]
3692(2)
Z
4
Crystal system
Space group
monoclinic
P21/n
Linear abs. coeff. µ [cmϪ1
]
10.4
Density ρ [g·cmϪ3
Diffractometer
Radiation
]
1.47
CAD4 EnrafϪNonius
CAD4 EnrafϪNonius
˚
˚
Mo-Kα (λ ϭ 0.71069 A )
Mo-Kα (λ ϭ 0.71069 A )
Scan type
Scan range [°]
θ Limits [°]
ω /2θ
ω/2θ
0.8 ϩ 0.345 tgθ
0.8 ϩ 0.345 tgθ
1Ϫ25
1Ϫ26
Temperature of measurement
Octants collected h; k; l
Decay%
295 K
223 K
0,13; 0,24; Ϫ18,18
0,13; Ϫ14,14; Ϫ19,19
<10
<10
No. of data collected
7041
8126
No. of unique data collect. (Rint
No. of unique data used for ref.
R ϭ ΣԽԽFoԽ Ϫ ԽFcԽԽ/ΣԽFoԽ
)
6483 (0.05)
7703 (0.03)
3057 (Fo)2 > 3σ(Fo)2
4787 (Fo)2 > 3σ(Fo)2
0.0506
0.0597
1.17
none
497
Ϫ0.42
0.87
0.0478
0.0563
1.11
none
488
Ϫ0.48
0.74
Rw* ϭ [Σw( Fo Ϫ Fc )2/Σw Fo 2]1/2
S
Extinction parameter
No. of variables
Ϫ3
˚
˚
∆ρmin [e·A
∆ρmax [e·A
]
Ϫ3
]
1
Spectroscopic Data for 19: H NMR (CD2Cl2): δ ϭ 7.39 (m, 5 H, refinable isotropic thermal parameter. Fractional parameters, an-
C6H5), 7.15 (s, 1 H, 3-H), 7.00 (s, 1 H, 1-H), 5.38 (s, 5 H, Cp). Ϫ
isotropic thermal parameters, and all bond lengths and angles are
given in the Supporting Information for complexes 5 and 17.
IR ν(CO): ν˜ ϭ 2052, 2006, 1993, 1907 cmϪ1
.
X-ray Structure Determination: Suitable crystals of [(Co2(-
CO)4dppm)(µ-η2,η2-RCϵCCH(CF3)(OH)] (5) were obtained by
slow evaporation of a saturated solution in pentane/Et2O (1:4),
while complex [{Co2(CO)4dppm}{µ-η2,η2-C6H5CϵCCH2(CF3)}]
(17) was obtained by slow evaporation of an acetone saturated
solution. The selected crystal of complex 5 or 17 was glued on the
top of a glass rod. Accurate cell dimensions and orientation matrix
were obtained by least-squares refinements of 25 accurately cen-
tered reflections on a Nonius CAD4 diffractometer equipped with
graphite-monochromated Mo-Kα radiation. No significant varia-
tions were observed in the intensities of two checked reflections
during data collection. The ψ-scan curve of 5 or 17 was flat, hence
no absorption correction was applied. Complete crystallographic
data and collection parameters for 5 and 17 are listed in Table
4. The data were corrected for Lorentz and polarization effects.
Computations were performed by using the PC version of CRYS-
TALS.[22] Scattering factors and corrections for anomalous disper-
sion were taken from ref.[23] Complex 5 exhibited a disordered be-
havior for the CF3ϪCϪOH unit. A best structural resolution was
achieved by considering two locations where the CF3ϪCϪOH frag-
ment displayed occupation factor of (43%) and (57%). The asym-
metric unit of complex 17 contains one molecule of solvated ace-
tone, thus crystals of 17 decomposed at room temperature by loss
of solvent and thus the X-ray data were recorded at low tempera-
ture. The structures of compounds 5 and 17 were refined by full-
matrix least-squares with anisotropic thermal parameters for all
non-hydrogen atoms. Hydrogen atoms were introduced in calcu-
lated positions in the last refinements and were allocated an overall
Acknowledgments
We would like to thank CNRS for supporting this work.
[1]
G. K. S. Prakash, A. K. Yudin, Chem. Rev. 1997, 97, 757Ϫ786.
[2]
A. D. Allen, T. T. Tidwell, in: Advances in Carbocation Chemis-
try (Ed.: X. Greary, JAI Press Inc. Greenwich, CT, 1989, 1Ϫ44.
[3]
T. Tsushima, K. Kawada, S. Ishihara, N. Uchida, O. Shiratori,
J. Higaki, M Hirita, Tetrahedron, 1998, 44, 5375Ϫ5387.
[4] [4a]
T. Hagiwara, K. Tanaka, T. Fuchikami, Tetrahedron Lett.
1996, 37, 8187Ϫ8190. Ϫ [4b] M. Neri, M. G. Brasca, A. Longo,
W. Moretti, A. Panzeri, Tetrahedron Lett. 1997, 38, 4881Ϫ4884.
[5] [5a]
H. Amouri, M. Gruselle, Chem. Rev. 1996, 96, 1077Ϫ1103.
[5b]
Ϫ
M. J. Mc Glinchey, L. Girard, R. Ruffolo, Coordination
[5c]
Chem. Rev. 1995, 143, 331Ϫ381. Ϫ
Chem. Res. 1987, 26, 207 Ϫ
K. M. Nicholas, Acc.
[5d]
G. G. Melikyan, K. M. Nich-
olas, “The Chemistry of MetalϪAlkyne Complexes” in: Mod-
ern Acetylene Chemistry (Eds.: P. J. Stang, F. Diederich), VCH
Publishers, 1995, 4, 99Ϫ138.
[6] [6a]
M. R. Tirpak, C. A. Hollingsworth, J. H. Wotiz, J. Or-
ganomet. Chem. 1960, 25, 687Ϫ690. Ϫ [6b] S. Padmanabhan, K.
[6c]
M. Nicholas, J. Organomet. Chem. 1981, 212, 115Ϫ124. Ϫ
G. G. Melikyan, O. Vostrowsky, W. Bauer, H. J. Bestmann, J.
[6d]
Organomet. Chem. 1992, 423, 24Ϫ27. Ϫ
K. L. Salazar, M.
A. Khan, K. M. Nicholas, J. Am. Chem. Soc. 1997, 119,
9053Ϫ9054.
[7]
[8]
G. G. Melikyan, R. C. Combs, J. Lamirand, M. Khan, K. M.
Nicholas, Tetrahedron Lett. 1994, 35, 363Ϫ366.
G. G. Melikyan, M. A. Khan, K. M. Nicholas, Organometallics,
1995, 14, 2170Ϫ2172.
Eur. J. Inorg. Chem. 2000, 359Ϫ368
367

M. Gruselle et al.
FULL PAPER
[9]
[18]
[19]
´
M. A. Kondratenko, B. Malezieux, M. Gruselle, D. Bonnet-
M. Gruselle, M. A. Kondratenko, H. Amouri, J. Vaissermann,
Organometallics, 1995, 14, 5242Ϫ5250.
´
´
Delpon, J. P. Begue, J. Organomet. Chem. 1995, 487, 15Ϫ17.
[10] [10a]
G. G. Melikyan, A. Deravakian, S. Myer, S. Yadegar, K. I.
Hardcastle, J. Ciurash, P. Toore, J. Organomet. Chem. 1999,
544, 143Ϫ145.
M. F. DЈAgostino, C. S. Frampton, M. J. Mc Glinchey,
Organometallics, 1990, 9, 2972Ϫ2984. Ϫ [10b] D. H. Bradley, M.
A. Khan, K. M. Nicholas, Organometallics, 1992, 11,
2598Ϫ2607.
D. H. Braley, M. A. Khan, K. M. Nicholas, Organometallics,
1989, 8, 554Ϫ556.
M. Gruselle, H. El Hafa, M. Nikolski, G. Jaouen, J. Vaisserm-
ann, L. Lijuan, M. J. Mc Glinchey, Organometallics, 1993, 12,
4917Ϫ4925.
G. G. Melikyan, A. Deravakian, J. Organomet. Chem. 1997,
578, 68Ϫ75.
[11]
[12]
[20]
J. Fossey, D. Lefort, J. Sorba, Les radicaux libres en chimie or-
ganique; Ed. Masson Paris, 1990.
[21] [21a]
R. Kaptein, in: Chemically Induced Magnetic Polarisation,
[21b]
Wiley-Interscience, New York 1973. Ϫ
hedron, 1975, 31, 2283Ϫ2287.
M. Gruselle, Tetra-
[13]
[14]
[15]
[16]
[17]
O. Kahn, D. Rau, H. Mayr, J. Am. Chem. Soc. 1998, 120,
[22]
D. J. Watkin, C. K. Prout, J. R. Carruthers, P. W. Betteridge;
Crystal issue 10, Chemical Crystallography Laboratory: Univer-
sity of Oxford UK, 1996.
900Ϫ907.
R. E Connor, K. M. Nicholas, J. Organomet. Chem. 1997,
125, 45Ϫ48.
M. Gruselle, C. Cordier, M. Salmain, H. Amouri, C. Guerin, J.
Vaissermann, G. Jaouen, Organometallics, 1990, 9, 2993Ϫ2997.
G. G. Melikyan, S. Bright, T. Monroe, K. I. Hardcastle, J. Ciur-
ash, Angew. Chem. Int. Ed. Engl. 1998, 37, 161Ϫ164.
[23]
[24]
D. T. Cromer, International Tables of X-ray Crystallography;
Kynoch Press Birmingham UK. 1974; Vol. IV.
L. J. Pearce and W. J. Watkin; Chemical Crystallography Labor-
atory, University of Oxford UK.
Received July 29, 1999
´
C. Cordier, PhD Universite Pierre et Marie Curie (France),
1991.
[I99282]
368
Eur. J. Inorg. Chem. 2000, 359Ϫ368