Reactions of half-sandwich ethene complexes of rhodium(I) toward iodoperfluorocarbons: Perfluoro-alkylation or -arylation of coordinated ethene versus oxidative addition

Article abstract of DOI:10.1021/om2009588

Perfluoroalkylation or perfluoroarylation of coordinated ethene takes place when complexes [Rh(η⁵-Cp*)(η²-C ₂H₄)₂] or [Rh(η⁵-Cp*) (η²-C₂H₄)(PR₃)] react with IR_F, to give complexes [Rh(η⁵-Cp*)(CH ₂CH₂R_F)(μ-I)]₂ (R_F = CF(CF₃)₂(1a), CF(CF₃)CF₂CF ₃ (1b), or C(CF₃)₃ (1c)) and [(η⁵-Cp*)IRh(μ-I)₂Rh(η⁵- Cp*)(CH₂CH₂R_F)] (2a-c), or [Rh(η⁵-Cp*)(CH₂CH₂R _F)I(PR₃)] (R = Me, R_F = CF(CF₃) ₂ (3a), C(CF₃)₃ (3c), C₆F ₅ (3d); R = Ph, R_F = CF(CF₃)₂ (3a′), CF₂C₆F₅ (3e′)), respectively. Bridge splitting reactions of 1a, 1b, or 1c with phosphines afford complexes [Rh(η⁵-Cp*)(CH₂CH₂R _F)I(PR₃)] (3a, 3a′, 3c; R_F = CF(CF ₃)₂, R = ⁱPr (3a″); R_F = CF(CF₃)CF₂CF₃, R = Me (3b), Ph (3b′)). In contrast, oxidative addition dominates over addition to ethene in the reactions of [Rh(η⁵-Cp*)(η²-C₂H ₄)(PMe₃)] with IR_F (R_F = CF ₂C₆F₅, ⁿC₃F₇, ⁿC₄F₉, CF=CF₂) and in the reaction of [Rh(η⁵-Cp)(η²-C₂H ₄)(PMe₃)] with IⁿC₄F₉, affording complexes of the type [Rh(η⁵-C₅R ₅)(R_F)I(PMe₃)] (4e-h and 5, respectively). The reaction of [Rh(η⁵-Cp*)(η²-C ₂H₄)(PR₃)] with ICF(CF₃)CF ₂CF₃ gives a mixture of cis- and trans-octafluoro-2-butene as the main fluoroorganic reaction product. Evidence for the intermediacy of R_F^- anions in these reactions has been obtained. 3a′ reacts with AgOTf (OTf = O₃SCF₃) and XyNC or CO to give complexes [Rh(η⁵-Cp*){CH₂CH ₂CF(CF₃)₂}(CNXy)(PPh₃)]OTf (6) or [Rh(η⁵-Cp*){C(O)CH₂CH₂CF(CF ₃)₂}(CO)(PPh₃)]OTf (7), respectively. Complex [Rh(η⁵-Cp*)I(py)(PMe₃)]BF₄ (8) was obtained either by reaction of (1) [Rh(η⁵-Cp*) (η²-C₂H₄)(PMe₃)] with [I(py)₂]BF₄ or (2) [Rh(η⁵-Cp*)I ₂(PMe₃)] with AgBF₄ and py. The crystal structures of 1a, 1b, 3c, 4g, 7, and 8 have been determined.

Full text of DOI:10.1021/om2009588

Article
pubs.acs.org/Organometallics
Reactions of Half-Sandwich Ethene Complexes of Rhodium(I) toward
Iodoperfluorocarbons: Perfluoro-alkylation or -arylation of
Coordinated Ethene versus Oxidative Addition†
Juan Gil-Rubio,* Juan Guerrero-Leal, María Blaya, and Jose Vicente
́
́ ́
Grupo de Química Organometalica, Departamento de Química Inorganica, Facultad de Química, Universidad de Murcia,
E-30071 Murcia, Spain
Delia Bautista
SAI, Universidad de Murcia, E-30071 Murcia, Spain
Peter G. Jones
Institut fur Anorganische und Analytische Chemie, Technische Universitat Braunschweig, Postfach 3329, 38023 Braunschweig,
̈
̈
Germany
S
* Supporting Information
ABSTRACT: Perfluoroalkylation or perfluoroarylation of coor-
dinated ethene takes place when complexes [Rh(η5-Cp*)-
(η2-C2H4)2] or [Rh(η5-Cp*)(η2-C2H4)(PR3)] react with IRF, to
give complexes [Rh(η5-Cp*)(CH2CH2RF)(μ-I)]2 (RF = CF(CF3)2
(1a), CF(CF3)CF2CF3 (1b), or C(CF3)3 (1c)) and [(η5-Cp*)-
IRh(μ-I)2Rh(η5-Cp*)(CH2CH2RF)] (2a−c), or [Rh(η5-Cp*)-
(CH2CH2RF)I(PR3)] (R = Me, RF = CF(CF3)2 (3a), C(CF3)3 (3c), C6F5 (3d); R = Ph, RF = CF(CF3)2 (3a′), CF2C6F5 (3e′)),
respectively. Bridge splitting reactions of 1a, 1b, or 1c with phosphines afford complexes [Rh(η5-Cp*)(CH2CH2RF)I(PR3)] (3a, 3a′,
3c; RF = CF(CF3)2, R = iPr (3a″); RF = CF(CF3)CF2CF3, R = Me (3b), Ph (3b′)). In contrast, oxidative addition dominates over
addition to ethene in the reactions of [Rh(η5-Cp*)(η2-C2H4)(PMe3)] with IRF (RF = CF2C6F5, nC3F7, nC4F9, CFCF2) and in the
reaction of [Rh(η5-Cp)(η2-C2H4)(PMe3)] with InC4F9, affording complexes of the type [Rh(η5-C5R5)(RF)I(PMe3)] (4e−h and 5,
respectively). The reaction of [Rh(η5-Cp*)(η2-C2H4)(PR3)] with ICF(CF3)CF2CF3 gives a mixture of cis- and trans-octafluoro-2-
butene as the main fluoroorganic reaction product. Evidence for the intermediacy of RF− anions in these reactions has been obtained.
3a′ reacts with AgOTf (OTf = O3SCF3) and XyNC or CO to give complexes [Rh(η5-Cp*){CH2CH2CF(CF3)2}(CNXy)(PPh3)]OTf
(6) or [Rh(η5-Cp*){C(O)CH2CH2CF(CF3)2}(CO)(PPh3)]OTf (7), respectively. Complex [Rh(η5-Cp*)I(py)(PMe3)]BF4 (8) was
obtained either by reaction of (1) [Rh(η5-Cp*)(η2-C2H4)(PMe3)] with [I(py)2]BF4 or (2) [Rh(η5-Cp*)I2(PMe3)] with AgBF4 and
py. The crystal structures of 1a, 1b, 3c, 4g, 7, and 8 have been determined.
Perfluoroiodocarbons usually react with complexes of the
type [M(η5-C5R5)L2] (M = Co, Rh or Ir; R = H or Me; L = CO
or PF3) by oxidative addition to give complexes [M(η5-C5R5)I-
(RF)L], where RF is a perfluorinated alkyl, aryl, or benzyl
group.19−31 However, reactions involving perfluoroalkylation
of ligands have been observed in a few cases (Scheme 1). For
instance, clean perfluoroalkylation at the η5-Cp ring was
observed in the reactions of [M(η5-Cp)(PMe3)2] (M = Co or
Rh) with InC3F7 or ICF(CF3)2,24,29,30 whereas mixtures of products
resulting from perfluoroalkylation at the metal, CO, or η5-Cp
ligands were formed in the reactions of [M(η5-Cp)(PMe3)(CO)]
INTRODUCTION
■
Despite the notable advances recently made in the field of
metal-catalyzed perfluoroalkylation of organic substrates,1−3
processes involving perfluoroalkyl metal complexes as inter-
mediates remain a challenge, because of the reluctance of these
complexes to undergo typical C−C bond formation reactions,
such as reductive elimination or insertion of unsaturated
molecules into the M−C bond.4−10 Alternatively, some metal
complexes are effective initiators of free radical perfluoroalkyl-
ations,11−16 but the selectivity of these reactions is difficult to
control.11,13,17 In this context, the direct perfluoroalkylation
of a substrate coordinated to a metal is of potential interest,18
since it provides a way to the selective formation of C−
perfluoroalkyl bonds avoiding the intermediacy of stable
metal perfluoroalkyls.
Special Issue: Fluorine in Organometallic Chemistry
Received: October 10, 2011
Published: November 29, 2011
© 2011 American Chemical Society
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the Rh−C bond44−46 occurred to afford an unusual highly
fluorinated acyl derivative.
Scheme 1
RESULTS AND DISCUSSION
■
Reactions of [Rh(η5-Cp*)(η2-C2H4)2] with Perfluoro-
iodocarbons. [Rh(η5-Cp*)(η2-C2H4)2] reacts with IRF
(Scheme 2) to give mainly ethene and complexes [Rh(η5-
Scheme 2
(M = Rh or Ir) with the same perfluoroalkyl iodides.32 Very
recently, the perfluoroalkylation of a CO ligand in the reaction
between [Ir(η5-Cp*)(CO)2] and perfluorocyclohexyl bromide
has been reported.33
Although complexes [Rh(η5-C5R5)(η2-C2H4)L] (R = H or
Me; L = phosphine or C2H4)34−37 have been known for a long
time, reports of their reactivity toward perfluoroalkyl iodides
or bromides are scarce. Thus, [Rh(η5-Cp)(η2-C2H4)2] was
reported to react with ICF3 or InC3F7 to give the oxidative
addition products [Rh(η5-Cp)(CF3)(μ-I)]2 or [Rh(η5-Cp)I-
(nC3F7)(η2-C2H4)],38 respectively. In contrast, [Rh(η5-C5Me5)-
(η2-C2H4)2] does not react with ICF2C6F5.39 The reactions of
[Rh(η5-Cp)(η2-C2H4)(PPh3)] with InC3F7 or BrCF2CF2Br also
proceed by oxidative addition, yielding compounds [Rh(η5-Cp)-
(RF)X(PPh3)] (X = I, RF = nC3F7; X = Br, RF = CF2CF2Br), but
the analogous reaction with ICF3 affords [Rh(η5-Cp)I2(PPh3)]
as the only isolated product.40 Oxidative addition of perfluoro-
alkyl iodides to the related complex [Rh(Tp)(η2-C2H4)2] (Tp =
tris(pyrazolyl)borate) has also been described.41 Therefore, we
decided to improve and extend the knowledge of the reactivity
of complexes of the type [Rh(η5-C5R5)(η2-C2H4)L] (R = H, Me;
L = PR3, C2H4) toward iodoperfluorocarbons. Interestingly,
these reactions proceed in most cases by perfluoroalkylation of
the coordinated ethene, rather than by oxidative addition. As far
as we are aware, perfluoroalkylation of coordinated ethene has
been reported only in the reaction of complexes [M(η5-Cp)2-
(η2-C2H4)] (M = Mo or W) with IC(CF3)3 to give [M(η5-
Cp)2{CH2CH2C(CF3)3}].42,43
Cp*)(CH2CH2RF)(μ-I)]2 (RF = CF(CF3)2 (1a), CF(CF3)-
CF2CF3 (1b), C(CF3)3 (1c)). Compounds 1a and 1b were
isolated as crystalline red solids containing small amounts
(10%) of [(η5-Cp*)IRh(μ-I)2Rh(η5-Cp*)(CH2CH2RF)] (2a,
2b, respectively). In the case of 1c, a greater amount of the
mixed iodide-bridged complex (2c), HC(CF3)3, and small
amounts of unidentified compounds were also formed. The
identity of complexes 1 was established on the basis of (1)
1
their H and 19F NMR data, (2) the characterization of the
products of their reactions with various phosphines (see
below), and (3) the X-ray structures of 1a and 1b. In addition,
the elemental analyses of samples of 1a or 1b containing 10%
1
(determined by H NMR) of 2a or 2b, respectively, agree
with the calculated values, supporting the formulation of both
components.
Complex 1a or 1b decomposes in solution at room
temperature over several days to give mainly 2a or 2b, together
with minor quantities of [Rh(η5-Cp*)I(μ-I)]2 and other
products that could not be identified. Hence, the presence
of small amounts of 2a or 2b could be attributed to
decomposition of 1a or 1b during the reaction time. In
contrast, the larger amounts of 2c and other products detected
in the reaction of [Rh(η5-Cp*)(η2-C2H4)2] with IC(CF3)3
cannot be attributed solely to decomposition of 1c and are
We also report the reactivity toward XyNC or CO of one of
the products obtained by perfluoroalkylation of the coordinated
ethene. Whereas in the first case a ligand substitution reaction
took place, in the second the insertion of a CO molecule into
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probably formed through an alternative reaction path (see
Mechanistic Studies).
In 1b, because of the presence of two chiral centers (at the
perfluoro-sec-butyl groups), two diastereomers are possible: the
racemic pair (with RR or SS configuration) and the meso
diastereomer (with RS configuration). However, in the single
crystal used for the X-ray structure determination only the meso
isomer was present. Indeed, the molecule of 1b is
centrosymmetric, whereas in 1a both CH2CH2CF(CF3)2
groups point to the same side of the molecule (as viewed
down the Rh−Rh axis) and the bond distances and angles are
slightly different for both metal fragments.
The crystal structures of 1a and 1b (Figures 1 and 2) show
the presence of iodo-bridged dimers with the pairs of η5-Cp*
1
In the H NMR spectra of 1a−c the methylene protons
appear as second-order multiplets around 3 ppm. The 19F NMR
spectrum of 1a displays a doublet and a multiplet, corresponding
to the CF3 and CF groups, respectively. The CF(CF3)CF2CF3
group of 1b gives five signals, corresponding to the CF, the
diastereotopic CF2 fluorines, and the CF3 groups. The identity
of complexes 2 in their mixtures with 1 was established on the
1
1
basis of their H and 19F NMR signals. Thus, the H spectra
show signals corresponding to two different η5-Cp* groups and
a complex multiplet around 3 ppm for the methylene protons,
and the 19F spectra display a set of signals at chemical shift
values very close to those of 1.
Although two diastereomers are expected for 1b, only one set
of signals was observed in its 1H and 19F NMR spectra, even at
low temperature and in a high-field spectrometer (−80 °C,
600 MHz). As the selective formation of one diastereomer of
1b is unlikely, this could be the result of both isomers having
Figure 1. Molecular structure of 1a (50% thermal ellipsoids). Selected
bond lengths (Å) and angles (deg): Rh(1)−CNT1 (CNT1 = centroid
of C1−5) 1.8250(19), Rh(1)−C(11) 2.111(4), Rh(1)−I(1)
2.7198(4), Rh(1)−I(2) 2.7077(4), Rh(2)−CNT2 (CNT2 = centroid
of C21−25) 1.8300(18), Rh(2)−C(31) 2.108(4), Rh(2)−I(1)
2.7100(4), Rh(2)−I(2) 2.6987(4), I(1)−Rh(1)−I(2) 87.229(11),
C(11)−Rh(1)−I(1) 87.19(10), C(11)−Rh(1)−I(2) 88.35(10),
C(31)−Rh(2)−I(2) 87.94(11), C(31)−Rh(2)−I(1) 85.90(10).
51
1
almost identical H and 19F NMR spectra.
NMR measurements on samples of 1a or 1b (containing
small amounts of 2a or 2b, respectively) treated with 1 equiv of
[Rh(η5-Cp*)I(μ-I)]2 revealed that compounds 1, 2, and
[Rh(η5-Cp*)I(μ-I)]2 are in equilibrium, whereby complexes 2
are the major components. This process is slow on the NMR
time scale at room temperature, but at about 80 °C the Cp*
signals of the three compounds coalesce into a unique signal in
1
the H NMR spectrum (D8-toluene). This could be explained
by an exchange process involving cleavage and restoration of
the iodide bridges with combination of the resulting fragments.
[Rh(η5-Cp*)(η2-C2H4)2] reacted neither in C6D6 solution
with InC4F9, IC6F5, or ICFCF2 at room temperature nor on
heating at 50 °C (InC4F9) or at 60 °C (IC6F5 or ICFCF2) for
several hours. Heating at higher temperatures led to mixtures of
products that were not identified. In agreement with previously
reported results, the reaction of [Rh(η5-Cp*)(η2-C2H4)2] and
ICF2C6F5 was sluggish, and, after 21 h at room temperature,
most starting material remained unreacted.39
Bridge-Cleavage Reactions. The reactions of the mix-
tures of complexes 1 + 2 with PMe3, PPh3, or PiPr3 led to
mononuclear complexes of the type [Rh(η5-Cp*)-
(CH2CH2RF)I(PR3)] (RF = CF(CF3)2, R = Me (3a), Ph
(3a′), iPr (3a″); RF = CF(CF3)CF2CF3, R = Me (3b), Ph (3b′);
RF = C(CF3)3, R = Me (3c); Scheme 2), which were isolated
with 50−82% yields after separation of the byproducts [Rh(η5-
Cp*)I2(PR3)] by crystallization or chromatography. Complexes
3b and 3b′ were isolated as mixtures of two diastereomers
arising from the presence of two stereogenic centers in the
molecule, one at the perfluoro-sec-butyl group and another at
the Rh atom. The diastereomeric ratios were close to unity (1:1
and 1:1.1, respectively). This implies a negligible influence of
the configuration of the perfluoro-sec-butyl group on the side of
the attack of the phosphine to the metal, which is in turn
attributable to the long distance between the stereogenic
carbon atom and the metal.
Figure 2. Molecular structure of 1b (50% thermal ellipsoids). Selected
bond lengths (Å) and angles (deg): Rh(1)−CNT1 (CNT1 = centroid
of C1−5) 1.820(3), Rh(1)−C(11) 2.111(6), Rh(1)−I(1) 2.7060(6),
Rh(1)−I(1A) 2.7134(6), C(11)−Rh(1)−I(1) 89.44(17), C(11)−
Rh(1)−I(1A) 88.87(17), I(1)−Rh(1)−I(1A) 86.513(18), Rh(1)−
I(1)−Rh(1A) 93.487(18).
and C2H4RF ligands necessarily mutually trans. This arrange-
ment is usually adopted by halide-bridged pentamethylcyclo-
pentadienyl complexes of Rh or Ir in order to reduce steric
hindrance.39,47−50 For the same reason, the CH2CH2RF chains
are extended away from the metal. Bond distances and angles in
the coordination sphere are very similar for both complexes.
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Reactions of [Rh(η5-Cp*)(η2-C2H4)(PR3)] (R = Me or Ph)
with Perfluoroiodocarbons. The reactions between in situ
generated [Rh(η5-Cp*)(η2-C2H4)(PR3)] and IRF (Scheme 3
products were tentatively identified in the reaction mixtures.
Significant amounts of HRF were also formed in the reactions
leading to 4g and 4h.
The reaction of [Rh(η5-Cp)(η2-C2H4)(PMe3)] with InC4F9
(Scheme 4) gave [Rh(η5-Cp)(nC4F9)I(PMe3)] (5), which was
Scheme 3
Scheme 4
isolated and characterized. In contrast, the reactions of the
same complex with ICF(CF3)2, IC6F5, or ICFCF2 led to
intractable mixtures containing large amounts of [Rh(η5-Cp)-
I2(PMe3)].
and Table 1) led, in general, to mixtures containing the ethene
perfluoroalkylation or perfluoroarylation products (3), the
oxidative addition products (4), complexes [Rh(η5-Cp*)-
I2(PR3)] (R = Me or Ph), and other products that could not
be separated and identified. The nature of the main reaction
product depends on R and RF. Thus, addition to ethene prevails
in the reactions of [Rh(η5-Cp*)(η2-C2H4)(PMe3)] with
ICF(CF3)2, IC(CF3)3, or IC6F5 and in the reactions of
[Rh(η5-Cp*)(η2-C2H4)(PPh3)] with ICF(CF3)2 or ICF2C6F5
to give complexes 3a, 3c, 3d, 3a′, and 3e′ (Scheme 3),
respectively, which were isolated in 12−80% yields (Table 1).
The corresponding oxidative addition products were not
detected in these reactions except for ICF2C6F5, where a
minor amount was tentatively identified in the NMR spectra
of the reaction mixture. In contrast, oxidative addition is
dominant for the reactions of [Rh(η5-Cp*)(η2-C2H4)(PMe3)]
with ICF2C6F5, InC3F7, and InC4F9, which gave the previously
reported [Rh(η5-Cp*)(RF)I(PMe3)] (RF = CF2C6F5 (4e)22 or
nC3F7 (4f)21) and the new compound [Rh(η5-Cp*)(nC4F9)I-
(PMe3)] (4g). Complexes 4e and 4g were isolated, but 4f was
identified in the reaction mixture by comparison of its NMR
signals with those reported. Finally, the reaction of [Rh(η5-
Cp*)(η2-C2H4)(PMe3)] with ICFCF2 gave [Rh(η5-Cp*)-
I2(PMe3)] as the main product, and the oxidative addition
product 4h was isolated in low yield by chromatography. In the
reactions leading to 4e−h, only minor amounts of the
corresponding ethene perfluoro(alkylation or vinylation)
The obtained complexes gave the expected signals in their
NMR spectra. Because of the presence of a stereogenic center
at the metal, the four methylene protons of complexes 3 appear
1
inequivalent in their H NMR spectra. For the same reason,
two signals are observed for the CF3 groups of 3a, 3a′, and 3a″
and for the CF2 fluorines of 3b and 3b′. The 31P{1H} spectra of
complexes 3 showed a doublet as a consequence of the coupl-
ing with 103Rh. In contrast, the oxidative addition complexes
gave doublets of multiplets (4g and 5) or a doublet of doublets
(4h) because of the coupling of 31P with 103Rh and with the 19
F
nuclei of the rhodium-bound nC4F9 or CFCF2 groups,
respectively. The signals of 3b and 3b′ were duplicated because
of the presence of two diastereomers (see above).
The crystal structures of 3c and 4g were determined by
single-crystal X-ray diffraction (Figures 3 and 4). In both
Table 1. Composition (%) of the Mixture of Products of the
a
Reaction [Rh(η5-Cp*)(η2-C2H4)(PR3)] + IRF
attack on
ethene
oxidative
addition
[Rh(η5-Cp*)
I2(PR3)]
RF
R
CF(CF3)2
CF(CF3)2
C(CF3)3
C6F5
Me
Ph
51 (3a)
91 (3a′)
100 (3c)
57 (3d)
0
0
5
5
0
Figure 3. Molecular structure of 3c (50% thermal ellipsoids). Selected
bond lengths (Å) and angles (deg): Rh(1)−CNT (CNT = centroid of
C1−5) 1.8789(16), Rh(1)−C(11) 2.120(3), Rh(1)−P(1) 2.2594(9),
Rh(1)−I(1) 2.6989(4), C(11)−Rh(1)−P(1) 85.31(10), C(11)−
Rh(1)−I(1) 96.26(9), P(1)−Rh(1)−I(1) 89.02(3).
Me
Me
Me
Ph
0
0
0
4
CF2C6F5
CF2C6F5
nC3F7
64 (4e)
15
31
27
24
40
b
40 (3e′)
≤10
b
Me
Me
Me
≤7
40 (4f)
40 (4g)
19 (4h)
b
nC4F9
≤5
molecules, the fluorinated alkyl group is extended away from
the metal in order to reduce steric repulsions with the η5-Cp*
and PMe3 ligands. The Rh−CH2 distance in 3c (2.120(3) Å) is
not significantly different from those of 1a (2.111(4) and
2.108(4) Å) or 1b (2.111(6) Å). The terminal Rh−I bond of
b
CFCF2
≤7
a
Estimated by integration of the 31P{1H} NMR spectrum of the
b
reaction mixture (error 5%). Tentatively identified in the NMR
spectra of the mixture.
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−
Information) also indicated the presence of the anions H2F3 ,
HF2 , and SiF62−, the latter probably being produced by F−
−
attack on the NMR tube glass (see below).53−55
Reactions of 3a′ with AgOTf and XyNC or CO. The
reaction of 3a′ with AgOTf and XyNC gave the cationic
derivative [Rh(η5-Cp*){CH2CH2CF(CF3)2}(PPh3)(CNXy)]-
OTf (6) (Scheme 6). In contrast, the analogous reaction of
Scheme 6
Figure 4. Molecular structure of 4g (50% thermal ellipsoids). Selected
bond lengths (Å) and angles (deg): Rh(1)−CNT (CNT = centroid of
C1−5) 1.8872(8), Rh(1)−P(1) 2.2967(5), Rh(1)−I(1) 2.68611(19),
Rh(1)−C(11) 2.0716(19), P(1)−Rh(1)−I(1) 88.673(13), C(11)−
Rh(1)−I(1) 89.71(5), C(11)−Rh(1)−P(1) 92.48(5), F(1)−C(11)−
Rh(1) 108.80(11), F(2)−C(11)−Rh(1) 116.91(12), F(2)−C(11)−
F(1) 103.06(14).
3c (Rh−I: 2.6989(4) Å) is slightly shorter than the bridging
Rh−I bonds of 1a and 1b (Rh−I: 2.6987(4)−2.7198(4) Å).
The Rh−CNT (CNT = centroid of the η5-Cp* ring) distance is
longer in 3c (1.8789(16) Å) and 4g (1.8872(8) Å) than in 1a
(1.8250(19) and 1.8300(18) Å) or 1b (1.820(3) Å), suggesting
that the steric repulsions between the η5-Cp* and PMe3 ligands
could be responsible for these differences. The Rh−CNT, Rh−P,
and Rh−C bond distances of 4g are not significantly different
from the values reported for [Rh(η5-Cp*)Cl(nC3F7)(PMe3)].52
The reaction of [Rh(η5-Cp*)(η2-C2H4)(PR3)] with ICF-
(CF3)CF2CF3 (Scheme 5) deserves special consideration, since
3a′ with CO led to complex [Rh(η5-Cp*){CH2CH2CF(CF3)2}-
(PPh3)(CO)]OTf (7), which resulted from insertion of a
molecule of CO into the Rh−CH2 bond and coordination of
another CO molecule to the metal.
Compounds 6 and 7 gave the expected signals in their NMR
spectra. The IR spectrum of the isonitrile complex 6 showed a
band at 2133 cm−1 corresponding to the ν(CN) mode. The
IR spectra of the carbonyl complex 7 displayed a band at 2043
cm−1 corresponding to the ν(CO) mode and another at
1682 cm−1 corresponding to the ν(CO) mode.
The crystal structure of 7 was determined by single-crystal
X-ray diffraction (Figure 5). The Rh−Ccarbonyl and CO
Scheme 5
no oxidative addition product and only traces of the ethene
perfluoroalkylation product were detected in the NMR spectra
of the reaction mixture (C6D6). Instead, the main reaction
products were cis-octafluoro-2-butene, trans-octafluoro-2-
butene, [Rh(η5-Cp*)I2(PMe3)], and a crystalline red precipitate.
The ESI-MS spectrum of this precipitate indicated that it was a
salt of the cation [Rh(η5-Cp*)I(PMe3)2]+, which was
Figure 5. Molecular structure of 7 (50% thermal ellipsoids). Selected
bond lengths (Å) and angles (deg): Rh(1)−CNT (CNT = centroid of
C1−5) 1.9096(13), Rh(1)−C(11) 1.898(3), Rh(1)−C(12) 2.083(3),
Rh(1)−P(1) 2.3380(7), C(11)−O(1) 1.130(4), C(12)−O(2)
1.200(4), C(11)−Rh(1)−C(12) 95.00(12), C(11)−Rh(1)−P(1)
91.99(9), C(12)−Rh(1)−P(1) 87.15(8).
1
confirmed by comparing its H and 31P{1H} NMR spectra
with those of the reported [Rh(η5-Cp*)I(PMe3)2]PF6.37
1
In addition, the H and 19F NMR spectra of the salt (see
Experimental Section and Figure S1 of the Supporting
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distances (1.898(3) and 1.130(4) Å) fall in the range of values
found for Rh(III) carbonyl complexes containing the η5-Cp*
ligand (1.800−2.041 and 1.040−1.149 Å, respectively).56 The
Rh−Cacyl distance (2.083(3) Å) is slightly longer than those
observed in other Rh(III) acyl complexes containing the η5-Cp*
ligand (2.010−2.071 Å).
(in D8-toluene), or IC6F5 (in C6D6) were dramatically affected
by the presence of CH3OD (1.5−2.5 equiv). Under these con-
ditions, the formation of complex 3a, 3c, or 3d was inhibited or
severely reduced, DRF being the main fluoroorganic product.
Moreover, significant amounts of DC(CF3)3 or DC6F5 were
detected when the reactions between [Rh(η5-Cp*)(η2-C2H4)-
(PMe3)] and IC(CF3)3 or IC6F5 were run in C6D6 saturated
with D2O. Minor amounts of HRF were also detected in all these
experiments, even in the absence of CH3OD, which might be
attributed to carbanion protonation by residual water or to the
contribution of a minor reaction pathway involving perfluoroalkyl
radicals.67 The reactions of [Rh(η5-Cp*)(η2-C2H4)2] with
ICF(CF3)2 or ICF(CF3)CF2CF3 in C6D6 were not significantly
affected when they were carried out in the presence of CH3OD or
in D2O-saturated solvent. In contrast, the analogous reactions
involving IC(CF3)3 gave considerable amounts of DC(CF3)3.
Evidence for both radical and anions was obtained in the
reaction of [Rh(η5-Cp*)(η2-C2H4)(PMe3)] with InC4F9 in C6D6.
Thus, the formation of the oxidative addition product 4g was
partially inhibited by carrying out the reaction in the presence of
norbornene or TEMPO (2 equiv), and significant amounts of
DnC4F9 were observed by carrying it out in the presence of
CH3OD (2.5 equiv). This suggests that, in this case, both ionic
and radical pathways should contribute significantly to the overall
reaction mechanism.
Mechanistic Studies. It is interesting to trace a parallelism
between the reactions observed and the reaction of [Rh(η5-Cp*)-
(η2-C2H4)(PMe3)] with MeI, which led to [Rh(η5-Cp*)(η2-C2H4)-
(Me)(PMe3)]I through nucleophilic attack of the metal center
at the positively charged carbon atom.37 Substitution of the
coordinated ethene by iodide finally gives [Rh(η5-Cp*)I(Me)-
(PMe3)]. The iodine-bound carbon of a perfluoroalkyl iodide
also bears a high positive charge, but it is sterically and electro-
statically shielded from nucleophilic attack by the negatively
charged fluorine substituents, especially in secondary and tertiary
perfluoroalkyl iodides.57,58 In addition, the electron-withdrawing
character of the perfluoroalkyl group makes the iodine atom
electrophilic, allowing nucleophilic attack and subsequent release
of a perfluoroalkyl anion.57−60 Such anions have been trapped by
Hughes and co-workers in the reactions of Rh(I),29 Mo(II),42,43
W(II),42,43 or Pt(II)61 complexes with perfluoroalkyl iodides. In a
benchmark study,42 the same authors reported that the ethene
complexes [M(η5-Cp)2(η2-C2H4)] (M = Mo or W) react with
IC(CF3)3 to give [M(η5-Cp)2I{CH2CH2C(CF3)3}] via nucleo-
philic attack of the metal at the iodine, followed by addition of
the generated C(CF3)3− anion to the coordinated ethene.42,43
Alternatively, the possibility of a radical mechanism should
be considered, since perfluoroalkyl iodides are able to react with
electron donors by single electron transfer to give I− and an RF·
radical.11,62 Considering these precedents, we attempted to find
experimental evidence for the intermediacy of RF· radicals or
Finally, the detection of cis- and trans-octafluoro-2-butene in
the reaction of [Rh(η5-Cp*)(η2-C2H4)(PMe3)] with ICF(CF3)-
CF2CF3 is evidence for the generation of the CF3CF2(CF3)CF−
anion, which decomposes by elimination of F− to give the alkenes.
The released fluoride anion could trap a proton from residual
moisture or react with glass to form the HnFn+1− and SiF62− anions
of the isolated salt. No perfluoroalkenes were detected in other
reaction mixtures examined by 19F NMR spectroscopy.
−
RF anions in the ethene perfluoroalkylation reactions.
On the basis of these results, we propose (Scheme 7) that
ethene perfluoro(alkylation or arylation) could occur by
As D8-toluene is expected to react with free RF· radicals to
give a D7-benzyl radical and DRF,61 some representative
reactions were conducted in this solvent. However, no DRF
was detected by NMR spectroscopy in any experiment.
Scheme 7
As perfluoroalkyl radicals easily add to olefins,11,63,64 the
reactions between [Rh(η5-Cp*)(η2-C2H4)(PMe3)] and ICF-
(CF3)2 were performed in the presence of a 4-fold excess of
norbornene. However, the outcome of the reaction was not
appreciably altered, and no significant amounts of norbornene
perfluoroalkylation products were detected.
In addition, the reactions of [Rh(η5-Cp*)(η2-C2H4)(PMe3)]
or [Rh(η5-Cp*)(η2-C2H4)2] with ICF(CF3)2 were carried out
in the presence of the radical trap (2,2,6,6-tetramethylpiperidin-
1-yl)oxyl (TEMPO), using C6D6 as solvent. While in the first
case the result of the reaction was essentially the same as in the
absence of the radical trap, in the second case most of the
starting materials remained unreacted after 16 h. As no radical-
trapping products were detected, the reaction inhibition is
tentatively attributed to competitive formation of a halogen-
bonded adduct between TEMPO and the perfluoroalkyl
iodide.60 The formation of this adduct did not compete effec-
tively with the rapid reaction between complex [Rh(η5-Cp*)-
(η2-C2H4)(PMe3)] and ICF(CF3)2.
nucleophilic attack of the metal on the iodine atom to generate
the ionic intermediate A, which could undergo addition of the
−
RF anion on the coordinated ethene to give complexes 3.
When L = C2H4, dinuclear species 1 could be formed by loss of
We also attempted to trap radical or carbanionic
intermediates by carrying out the reactions in the presence of
CH3OD as previously reported.29,42,61,65 In these experiments,
RF· radicals should preferentially cleave the weaker C−H
ethene and dimerization, although evidence for the formation
−
of RF anions was found only in the case of 1c.
Compounds [Rh(η5-Cp*)I2(PR3)] and other unidentified by-
products observed in the reactions of [Rh(η5-Cp*)(η2-C2H4)-
(PMe3)] with IRF could result from the evolution of intermediate A
after the dissociation of the ion pair and the destruction of the
bond66 to give HRF, whereas RF anions should abstract a D+
−
cation to give DRF. Thus, the reactions of [Rh(η5-Cp*)-
(η2-C2H4)(PMe3)] with ICF(CF3)2 (in D8-toluene), IC(CF3)3
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perfluoroalkyl anion by decomposition or by reaction with another
molecule. In particular, protonation by residual water would give
HRF, which was observed in the reactions leading to 4g or 4h. A
similar process could explain the formation of HC(CF3)3 and 2c in
the reaction of [Rh(η5-Cp*)(η2-C2H4)2] with IC(CF3)3.
Finally, we tried to prepare a salt containing the cation of
intermediate A by reaction of [Rh(η5-Cp*)(η2-C2H4)(PMe3)]
with the iodinating agent [I(py)2]BF4. However, substitution of
ethene by pyridine (py) took place in addition to iodination, to
give [Rh(η5-Cp*)I(py)(PMe3)]BF4 (8), which was also obtained
by reaction of [Rh(η5-Cp*)I2(PMe3)] with AgBF4 and pyridine.
The crystal structure of 8 was determined by single-crystal X-ray
diffraction (Figure 6).
EXPERIMENTAL SECTION
■
General Considerations. Complexes [Rh(η5-Cp*)(η2-C2H4)2]34
and [Rh(η5-Cp)(η2-C2H4)(PMe3)]35 were prepared as previously
reported. Solutions of complexes [Rh(η5-Cp*)(η2-C2H4)(PR3)]
(R = Me,37 Ph68) were prepared by heating a solution of [Rh(η5-Cp*)-
(η2-C2H4)2] and PMe3 or PPh3 at 120 °C in a Carius tube for 24 or 3.5 h,
respectively. Other reagents were obtained from commercial sources
and used without further purification: PMe3 (1 M solution in toluene),
IC6F5, InC4F9, InC3F7, ICF2C6F5, [I(py)2]BF4 (Aldrich), ICF(CF3)2
(Acros Organics), ICFCF2 (ABCR). The reactions were carried out
under an N2 atmosphere using standard Schlenk techniques. Test
reactions were performed in screw-cap NMR tubes equipped with a
PTFE-covered rubber septum. Toluene and n-pentane were degassed
and dried using a Pure Solv MD-5 solvent purification system from
Innovative Technology, Inc. D8-Toluene was deoxygenated by four
freeze−pump−thaw cycles, and C6D6 was distilled over CaH2. Both
solvents were stored under nitrogen over 4 Å molecular sieves.
Infrared spectra were recorded in the range 4000−200 cm−1 on a
Perkin-Elmer 16F PC FT-IR spectrometer with Nujol mulls between
polyethylene sheets. C, H, N, S analyses were carried out with Carlo
Erba 1108 and LECO CHS-932 microanalyzers. NMR spectra were
measured on Bruker Avance 200, 300, and 400 instruments. 1H
chemical shifts were referenced to residual C6D5H (7.15 ppm),
C6D5CD2H (2.09 ppm), CHDCl2 (5.29 ppm), or CHCl3 (7.26 ppm).
13C{1H} spectra were referenced to C6D6 (128.0 ppm), CDCl3
(77.0 ppm), or CD2Cl2 (53.8 ppm). 19F or 31P{1H} NMR spectra
were referenced to external CFCl3 or H3PO4 (0 ppm). The tem-
perature values in NMR experiments were not corrected. ESI-MS and
HR-MS spectra were measured on Agilent 5973 and 6620 spectro-
meters, respectively. A solution of NH4(HCO2) (5 mM) and HCO2H
(1%) in MeOH/H2O (75:25) was used as mobile phase unless other-
wise stated. Melting points were determined on a Reichert apparatus
in an air atmosphere.
[Rh(η5-Cp*){CH2CH2CF(CF3)2}(μ-I)]2 (1a) and [(η5-Cp*)IRh(μ-I)2-
Rh(η5-Cp*){CH2CH2CF(CF3)2}] (2a). ICF(CF3)2 (100 μL, 0.70 mmol)
was added to a solution of [Rh(η5-Cp*)(η2-C2H4)2] (186 mg,
0.63 mmol) in n-pentane (3 mL). After stirring for 18 h at room
temperature a red, microcrystalline solid precipitated, which was filtered,
washed with n-pentane (2 mL), and dried under vacuum (270 mg,
76%). Mp: 258−261 °C (dec). The isolated product contained 10%
of [(η5-Cp*)IRh(μ-I)2Rh(η5-Cp*){CH2CH2CF(CF3)2}] as determined
by integration of the 1H NMR spectrum. Anal. Calcd for (C30H38F14I2-
Rh2)0.9(C25H34F7I3Rh2)0.1: C, 31.72; H, 3.39. Found: C, 31.68; H, 3.66.
Figure 6. Molecular structure (30% thermal ellipsoids) of the cation of
the salt [Rh(η5-Cp*)I(C6H5N)(PMe3)]BF4 (8). Selected bond
lengths (Å) and angles (deg): Rh−CNT (CNT = centroid of C1−
5) 1.825, Rh−N(11) 2.1271(19), Rh−P 2.3160(7), Rh−I 2.6989(2),
N(11)−Rh−I 91.80(5), P−Rh−I 87.64(2), N(11)−Rh−P 90.66(6).
CONCLUDING REMARKS
■
Selective ethene perfluoroalkylation takes place in the reaction
of [Rh(η5-Cp*)(η2-C2H4)2] with secondary or tertiary
perfluoroalkyl iodides. In contrast, the course of the reactions
of [Rh(η5-Cp*)(η2-C2H4)(PMe3)] with perfluorinated iodides
depends on the fluoroorganic iodide used. Thus, ICF(CF3)2,
IC(CF3)3, and IC6F5 selectively attack at the ethene, while the
reactions with primary perfluoroalkyl iodides and ICF2C6F5 are
less selective and proceed preferentially through oxidative
addition. Attack at the ethene also prevails in the reaction of
[Rh(η5-Cp*)(η2-C2H4)(PPh3)] with ICF(CF3)2 or ICF2C6F5.
1
1a: H NMR (300.1 MHz, CDCl3): δ 2.85−2.58 (m, 8 H, CH2), 1.67
(s, 30 H, C5Me5); (300.1 MHz, C6D6) δ 3.15−2.90 (m, 8 H, CH2), 1.37
(s, 30 H, C5Me5). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 122.0 (dq,
1JCF = 288.6 Hz, 2JCF = 28.7 Hz, CF3), 95.2 (d, 1JRhC = 6.6 Hz, C5Me5),
38.1 (d, 2JFC = 20.8 Hz, CH2CF), 9.5 (s, C5Me5), 5.9 (d, 1JRhC = 24.9 Hz,
RhCH2). The signal corresponding to the CF carbon was not observed.
3
19F NMR (282.4 MHz, C6D6): δ −74.6 (d, JFF = 7.6 Hz, 6 F, CF3),
−181.7 (m, 1 F, CF). X-ray quality single crystals were obtained as
deuterobenzene monosolvate by slow evaporation of a C6D6 solution.
2a: 1H NMR (300.1 MHz, C6D6): δ 3.03−2.88 (m, 4 H, CH2), 1.53 (s,
15 H, C5Me5), 1.46 (s, 15 H, C5Me5). 19F NMR (282.4 MHz, C6D6): δ
3
−
−74.5 (d, JFF = 7.5 Hz, 6 F, CF3), −180.2 (m, 1 F, CF).
Evidence for the intermediacy of RF anions in the ethene
[Rh(η5-Cp*){CH2CH2CF(CF3)CF2CF3}(μ-I)]2 (1b) and [(η5-Cp*)-
IRh(μ-I)2Rh(η5-Cp*){CH2CH2CF(CF3)CF2CF3}] (2b). These were
prepared in the same way as 1a + 2a, starting from [Rh(η5-Cp*)-
(η2-C2H4)2] (48 mg, 0.16 mmol) and ICF(CF3)CF2CF3 (28 μL, 0.16
mmol) in n-pentane (3 mL). After stirring for 18 h, the reaction
mixture was stored at 4 °C for 3 days to give a red, crystalline solid.
The mother liquor was removed with a pipet in a ice−water bath, and
the solid was washed with cold (0 °C) n-pentane (3 × 1.5 mL) and
dried under vacuum (68 mg, 68%). Mp: 140 °C (dec). The isolated
product contained 10% of [(η5-Cp*)IRh(μ-I)2Rh(η5-Cp*)-
perfluoroalkylation or perfluoroarylation reactions points to a
mechanism where a cationic Rh(III) intermediate is formed by
the nucleophilic attack of the metal center at the iodine atom of
the perfluororganic iodide.
The reported reactions are rare examples of perfluoroalkyl-
ation or perfluoroarylation of a coordinated alkene and represent
a first step toward nonradical rhodium-catalyzed perfluoroalkyl-
ation of olefins avoiding the formation of perfluoroalkyl metal
intermediates. Studies aimed at the development of a rhodium-
mediated or -catalyzed olefin perfluoroalkylation reaction are in
progress.
1
{CH2CH2CF(CF3)CF2CF3}] as determined by integration of the H
NMR spectrum. Anal. Calcd for (C32H38F18I2Rh2)0.9(C26H34F9I3Rh2)0.1:
C, 31.11; H, 3.13. Found: C, 31.06; H, 3.08. 1b: 1H NMR (400.9 MHz,
C6D6): δ 3.19−2.93 (m, 8 H, CH2), 1.39 (s, 30 H, C5Me5). 13C{1H}
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NMR (100.8 MHz, CD2Cl2): δ 126.6−109.3 (several m, CFn), 95.2
Method B. A solution of 1a + 2a (101 mg, 0.086 mmol of 1a) and
PPh3 (52 mg, 0.20 mmol) in THF (5 mL) was stirred for 5 h. The
volatiles were removed under vacuum, and the resulting residue was
purified by column chromatography (see above) to give an orange,
crystalline solid (122 mg, 86%). Mp: 145−148 °C. Anal. Calcd for
2
(d, 1JRhC = 6.5 Hz, C5Me5), 38.6 (d, JFC = 21.6 Hz, RhCH2CH2), 9.5
1
(s, C5Me5), 6.2 (d, JRhC = 24.6 Hz, RhCH2). 19F NMR (188.3 MHz,
C6D6): δ −72.1 (br s, 3 F, CFCF3), −79.7 (dq, 4JFF = 5JFF = 5.1 Hz, 3
F, CF2CF3), −120.6 (m, 2 F, CF2), −180.9 (br m, 1 F, CF). (+)ESI-
MS: m/z 731 ([Rh2(C5Me5)2I2H]+), 857 ([Rh2(C5Me5)2I3]+), 977
([Rh2(C5Me5)2I2(CH2CH2C4F9)]+). X-ray quality single crystals were
1
C33H34F7IPRh: C, 48.08; H, 4.16. Found: C, 48.18; H, 4.24. H NMR
(400.9 MHz, C6D6): δ 7.72 (br m, 6 H, H2 of Ph), 6.99 (m, 9 H, H3
and H4 of Ph), 3.52 (m, 1 H, Rh−CH2−CH2), 2.38 (m, 1 H, Rh−
CH2−CH2), 2.08 (m, 1 H, Rh−CH2−CH2), 1.92 (m, 1 H, Rh−CH2−
CH2), 1.32 (d, 4JPH = 2.8 Hz, 15 H, C5Me5). 13C{1H} NMR (75.5 MHz,
CDCl3, 50 °C): δ 134.9 (br s, C2 of Ph), 133.0 (d, 1JPC = 44.2 Hz, C1 of
Ph), 130.1 (s, C4 of Ph), 127.9 (d, 3JPC = 9.9 Hz, C3 of Ph), 121.5 (dq,
1
obtained from an n-hexane solution at 4 °C. 2b: H NMR (400.9
MHz, C6D6): δ 3.08−2.91 (m, 4 H, CH2), 1.53 (s, 15 H, C5Me5), 1.48
(s, 15 H, C5Me5). 19F NMR (188.3 MHz, C6D6): δ −72.3 (br s, 3 F,
CFCF3), −79.7 (m, 3 F, CF2CF3), −120.5 (m, 2 F, CF2), −180.1
(br m, 1 F, CF).
1JCF = 286.1 Hz, 2JCF = 28.6 Hz, CF3), 99.8 (dd, 1JRhC = 4.6 Hz, 2JPC
=
[Rh(η5-Cp*){CH2CH2C(CF3)3}(μ-I)]2 (1c) and [(η5-Cp*)IRh(μ-I)2-
Rh(η5-Cp*){CH2CH2C(CF3)3}] (2c). These were prepared in the same
way as 1a + 2a, starting from [Rh(η5-Cp*)(η2-C2H4)2] (111 mg, 0.38
mmol) and IC(CF3)3 (185, mg, 0.53 mmol) in n-pentane (4 mL). The
reaction mixture was evaporated to dryness to give a dark red residue
containing 1c, a similar number of equivalents of 2c, and several
unidentified minor products (the integration of the 1H NMR spectrum
was not accurate because of signal overlap). Attempts to isolate 1c by
crystallization or column chromatography led to mixtures containing
2
3.3 Hz, C5Me5), 38.8 (d, JFC = 20.4 Hz, Rh−CH2−CH2), 9.3 (s,
1
2
C5Me5), 1.6 (dd, JRhC = 25.0 Hz, JPC = 13.4 Hz, Rh−CH2−CH2). At
room temperature the aromatic region of the spectrum is more complex
because of slow rotation of the phosphine ligand on the NMR time
scale.69 The signal corresponding to the CF carbon was not observed.
3
4
19F NMR (188.3 MHz, C6D6): δ −74.1 (dq, JFF = JFF = 8.5 Hz, 3 F,
3
4
CF3), −76.1 (dq, JFF = JFF = 8.5 Hz, 3 F, CF3), −182.4 (m, 1 F, CF).
1
31P{1H} NMR (81.0 MHz, C6D6): δ 41.6 (d, JRhP = 161.2 Hz).
1
[Rh(η5-Cp*){CH2CH2CF(CF3)2}I(PiPr3)] (3a″). PiPr3 (35 μL, 0.18
mmol) was added to a solution of 1a + 2a (85 mg, 0.072 mmol of 1a)
in CH2Cl2 (5 mL). The resulting solution was stirred for 13 h at room
temperature and evaporated to dryness. The residue was extracted
with n-pentane (15 mL), and the extract was filtered through Celite,
concentrated to ca. 2 mL, and stored at −32 °C for 4 h to give orange
crystals, which were washed with cold n-pentane (−30 °C, 3 × 1 mL)
and dried under vacuum (80 mg, 77%). Mp: 95−97 °C. Anal. Calcd
both products. 1c: H NMR (200.1 MHz, C6D6): δ 3.25 (m, 4 H,
CH2), 2.97 (m, 4 H, CH2), 1.38 (s, 30 H, C5Me5). 19F NMR (188.3
MHz, C6D6): δ −64.5 (s). 2c: 1H NMR (200.1 MHz, C6D6): δ 3.16−
2.90 (m, 4 H, CH2), 1.52 (s, 15 H, C5Me5), 1.49 (s, 15 H, C5Me5). 19
F
NMR (188.3 MHz, C6D6): δ −64.7 (s).
[Rh(η5-Cp*){CH2CH2CF(CF3)2}I(PMe3)] (3a). Method A. A mix-
ture of [Rh(η5-Cp*)(η2-C2H4)2] (147 mg, 0.50 mmol) and PMe3
(0.60 mmol) was heated in toluene (5 mL) at 120 °C for 24 h in a
Carius tube. The resulting solution of [Rh(η5-Cp*)(η2-C2H4)(PMe3)]
was cooled at room temperature, and then ICF(CF3)2 (74 μL,
0.50 mmol) was added. A color change from yellow to dark red took
place immediately. After stirring for 40 min, the volatiles were removed
under vacuum. The residue was extracted with Et2O (15 mL), and the
extract was chromatographed on a silica gel column using CH2Cl2 as
eluent. The collected fraction (Rf = 0.8) was evaporated to dryness to
give an orange, crystalline solid (151 mg, 47%).
1
for C24H40F7IPRh: C, 39.91; H, 5.58. Found: C, 39.70; H, 5.60. H
NMR (300.1 MHz, C6D6): δ 3.65 (m, 1 H, Rh−CH2−CH2), 2.35−
2.18 (m, 4 H, Rh−CH2−CH2 + PCH), 2.08 (m, 1 H, Rh−CH2−
CH2), 1.54−1.42 (m, 1 H, Rh−CH2−CH2), 1.46 (d, 4JPH = 2.3 Hz, 15
H, C5Me5), 1.12 (dd, 2JPH = 12.8 Hz, 3JHH = 7.3 Hz, 3 H, CHMe), 1.04
2
3
(dd, JPH = 12.6 Hz, JHH = 7.2 Hz, 3 H, CHMe). 13C{1H} NMR
1
2
(100.8 MHz, C6D6): δ 122.2 (dq, JCF = 283.2 Hz, JCF = 29.7 Hz,
CF3), 99.8 (dd, 1JRhC = 4.4 Hz, 2JPC = 2.8 Hz, C5Me5), 39.5 (d, 2JFC
=
1
Method B. ICF(CF3)2 (100 μL, 0.70 mmol) was added to a
solution of [Rh(η5-Cp*)(η2-C2H4)2] (200 mg, 0.68 mmol) in n-
pentane (5 mL), and the mixture was stirred for 15 h. The dark red
suspension was evaporated to dryness under vacuum, and the residue
was dissolved in THF (5 mL). PMe3 (0.74 mmol) was added to the
solution, and the mixture was stirred for 3 h. Then, the volatiles were
removed under vacuum, and the resulting residue was purified by
chromatography as mentioned above (215 mg, 50%). Mp: 91−93 °C.
Anal. Calcd for C18H28F7IPRh: C, 33.88; H, 4.42. Found: C, 34.02; H,
4.74. 1H NMR (400.9 MHz, C6D6): δ 3.03 (m, 1 H, Rh−CH2−CH2),
2.26 (m, 1 H, Rh−CH2−CH2), 1.70 (m, 1 H, Rh−CH2−CH2), 1.50
(m, 1 H, Rh−CH2−CH2), 1.46 (d, 4JPH = 2.9 Hz, 15 H, C5Me5), 1.15
(dd, 2JPH = 9.8 Hz, 3JRhH = 0.6 Hz, 9 H, PMe3). 13C{1H} NMR (100.8
MHz, C6D6): δ 122.2 (dq, 1JCF = 287.0 Hz, 2JCF = 29.0 Hz, CF3), 98.2
20.5 Hz, Rh−CH2−CH2), 27.9 (d, JPC = 18.7 Hz, PCH), 21.0 (br s,
2
CHMe), 20.5 (d, JPC = 1.1 Hz, CHMe), 10.2 (s, C5Me5), −5.0 (dd,
1JRhC = 26.4 Hz, JPC = 14.7 Hz, Rh−CH2−CH2). The signal corre-
2
sponding to the CF carbon was not observed. 19F NMR (188.3 MHz,
C6D6): δ −73.9 (dq, 3JFF = 4JFF = 8.5 Hz, 3 F, CF3), −76.0 (dq, 3JFF
=
4JFF = 8.9 Hz, 3 F, CF3), −182.8 (m, 1 F, CF). 31P{1H} NMR (81.0
1
MHz, C6D6): δ 42.9 (d, JRhP = 153.0 Hz).
[Rh(η5-Cp*){CH2CH2CF(CF3)CF2CF3}I(PMe3)] (3b). A solution of
[Rh(η5-Cp*)(η2-C2H4)2] (70 mg, 0.24 mmol) in n-pentane (4 mL)
was treated with ICF(CF3)CF2CF3 (40 μL, 0.24 mmol) at room
temperature. After stirring for 20 h at room temperature, PMe3
(0.24 mmol) was added. The solution was stirred at room temperature
for 2 h and evaporated to dryness under vacuum. The residue was
extracted with n-pentane (15 mL). The extract was filtered, concentrated
under vacuum to ca. 2 mL, and stored at −32 °C for 24 h to give orange
crystals, which were washed with cold n-pentane (3 × 1 mL) and dried
under vacuum (87 mg, 53%). Mp: 100−102 °C. Anal. Calcd for
C19H28F9IPRh: C, 33.16; H, 4.10. Found: C, 33.19; H, 3.97. 1H NMR
(300.1 MHz, CDCl3): δ 2.59 (m, 1 H, Rh−CH2−CH2), 2.08 (m, 1 H,
Rh−CH2−CH2), 1.78 (d, 4JPH = 2.8 Hz, 15 H, C5Me5), 1.57 (m, 1 H,
1
2
2
(dd, JRhC = 5.0 Hz, JPC = 3.5 Hz, C5Me5), 38.1 (dd, JFC = 20.7 Hz,
3JPC = 4.8 Hz, CH2CF), 17.1 (d, 1JPC = 32.3 Hz, PMe3), 9.7 (s, C5Me5),
−0.6 (dd, 1JRhC = 26.0 Hz, 2JPC = 14.9 Hz, Rh−CH2−CH2). The signal
corresponding to the CF carbon was not observed. 19F NMR (188.3
MHz, C6D6): δ −74.7 (dq, 3JFF = 4JFF = 8.3 Hz, 3 F, CF3), −75.4 (dq,
4
3JFF = JFF = 8.3 Hz, 3 F, CF3), −182.0 (m, 1 F, CF). 31P{1H} NMR
2
1
Rh−CH2−CH2), 1.54 (d, JPH = 9.8 Hz, 9 H, PMe3), 1.33 (m, 1 H,
(162.3 MHz, C6D6): δ 2.8 (d, JRhP = 156.4 Hz).
[Rh(η5-Cp*){CH2CH2CF(CF3)2}I(PPh3)] (3a′). Method A. [Rh-
(η5-Cp*)(η2-C2H4)(PPh3)] was generated in situ by heating a solution
of [Rh(η5-Cp*)(η2-C2H4)2] (151 mg, 0.51 mmol) and PPh3 (162 mg,
0.62 mmol) in toluene (5 mL) at 120 °C for 3.5 h in a Carius tube.
After cooling to room temperature, ICF(CF3)2 (80 μL, 0.55 mmol)
was added to the resulting yellow solution, which changed color to
dark red. After stirring for 40 min, the volatiles were removed under
vacuum. The residue was extracted with Et2O, and the extract was
chromatographed on a silica gel column using Et2O/n-hexane (1:1) as
eluent. The collected orange fraction (Rf = 0.6) was evaporated to
dryness to give an orange, crystalline solid (205 mg, 49%).
Rh−CH2−CH2); (300.1 MHz, C6D6) δ 3.10 (m, 1 H, Rh−CH2−
CH2), 2.30 (m, 1 H, Rh−CH2−CH2), 1.73 (m, 1 H, Rh−CH2−CH2),
1.50 (m, 1 H, Rh−CH2−CH2), 1.44 (d, 4JPH = 2.9 Hz, 15 H, C5Me5),
1.114 (dd, 2JPH = 9.8 Hz, 3JRhH = 0.7 Hz, 9 H, PMe3), 1.111 (dd, 2JPH
=
3
9.8 Hz, JRhH = 0.7 Hz, 9 H, PMe3). 13C{1H} NMR (75.5 MHz,
1
CDCl3): δ 127.5−108.1 (several m, CFn), 98.6 (dd, JRhC = 3.2 Hz,
2JPC = 1.5 Hz, C5Me5), 98.5 (dd, 1JRhC = 3.2 Hz, 2JPC = 1.5 Hz, C5Me5),
37.7 (d, 2JFC = 24.0 Hz, Rh−CH2−CH2), 37.4 (d, 2JFC = 25.0 Hz, Rh−
CH2−CH2), 17.5 (dd, 1JPC = 32.4 Hz, 2JRhC = 0.7 Hz, PMe3), 17.4 (dd,
2
1JPC = 32.5 Hz, JRhC = 0.6 Hz, PMe3), 10.01 (s, C5Me5), 10.00 (s,
1
2
C5Me5), 0.2 (dd, JRhC = 25.6 Hz, JPC = 14.7 Hz, Rh−CH2−CH2).
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19F NMR (282.4 MHz, C6D6): δ −72.0 (s, 3 F, CF3CF, isomer A),
−72.7 (s, 3 F, CF3CF, isomer B), −79.5 (s, 3 F, CF3CF2, isomer A),
−79.7 (s, 3 F, CF3CF2, isomer B), −120.2 (AB doublet of multiplets,
2JFF = 292.6 Hz, 1 F, CF2, isomer A), −120.3 (m, 2 F, CF2, isomer B),
−121.5 (AB doublet of multiplets, 2JFF = 293.7 Hz, 1 F, CF2, isomer A),
−180.8 (m, 1 F, CF, isomer A), −181.3 (m, 1 F, CF, isomer B).
31P{1H} NMR (162.3 MHz, C6D6): δ 2.4 (d, 1JRhP = 156.8 Hz), 2.2 (d,
1JRhP = 156.8 Hz). (+)ESI-MS: m/z 347, 441 ([Rh(η5-Cp*)I(PMe3)]+),
533, 711 ([M + Na]+); exact mass calcd for C19H28F9INaPRh 710.9777,
found 710.9778, Δ = 0.14 ppm.
CH2−CH2), 17.5 (dd, 1JPC = 32.5 Hz, 2JRhC = 0.5 Hz, PMe3), 10.1 (d,
2JRhC = 1.1 Hz, C5Me5), 1.6 (dd, 1JRhC = 25.6 Hz, 2JPC = 14.4 Hz, Rh−
CH2−CH2). 19F NMR (188.3 MHz, C6D6): δ −65.0 (s). 31P{1H}
1
NMR (121.4 MHz, C6D6): δ 2.6 (d, JRhP = 156.4 Hz). (+)ESI-MS:
m/z 347, 441 ([Rh(η5-Cp*)I(PMe3)]+), 706 ([M + NH4]+); exact mass
calcd for C19H32NF9IPRh 706.0223, found 706.0223.
[Rh(η5-Cp*)(CH2CH2C6F5)I(PMe3)] (3d). This was prepared from
[Rh(η5-Cp*)(η2-C2H4)2] (128 mg, 0.44 mmol), PMe3 (0.44 mmol),
and IC6F5 (59 μL, 0.44 mmol) in a similar way to 3a (method A).
Column chromatography (silica gel) using Et2O/n-hexane (3:1) as
eluent gave an orange fraction (Rf = 0.87), which was evaporated to
dryness to give an orange oil (130 mg, 47%). Crystalline 3d was
obtained by slow diffusion of n-hexane into a C6D6 solution. Mp:
148−151 °C. Anal. Calcd for C21H28F5IPRh: C, 39.64; H, 4.44. Found:
C, 39.60; H, 4.60. 1H NMR (400.9 MHz, C6D6): δ 2.84 (m, 1 H, Rh−
CH2−CH2), 2.38 (m, 1 H, Rh−CH2−CH2), 1.96 (m, 1 H, Rh−CH2−
[Rh(η5-Cp*){CH2CH2CF(CF3)CF2CF3}I(PPh3)] (3b′). PPh3 (19 mg,
0.072 mmol) was added to a solution of 1b + 2b (43 mg, 0.034 mmol
of 1b) in CH2Cl2 (5 mL). The mixture was stirred for 20 h and
evaporated to dryness under vacuum. The residue was extracted with
n-pentane (5 mL). The extract was filtered, concentrated to ca. 1 mL,
and stored at −32 °C for 24 h. The orange-red crystals that formed
were separated from the mother liquor and washed twice with 1 mL
portions of cold n-pentane (46 mg, 77%). Mp: 131−133 °C. Anal.
Calcd for C34H34F9IPRh: C, 46.70; H, 3.92. Found: C, 46.62; H, 3.44.
1H NMR (300.1 MHz, C6D6): δ 7.73 (br m, 6 H, Ph), 7.00 (br m, 9 H,
Ph), 3.56 (m, 1 H, Rh−CH2−CH2), 2.44 (m, 1 H, Rh−CH2−CH2),
2.16−1.87 (m, 2 H, Rh−CH2−CH2), 1.33 (s, 15 H, C5Me5), 1.32 (d,
15 H, C5Me5); (400.9 MHz, CDCl3) δ 7.65−7.34 (br m, 15 H, Ph),
2.94 (m, 1 H, Rh−CH2−CH2), 2.07 (m, 1 H, Rh−CH2−CH2), 1.76−
1.65 (m, 2 H, Rh−CH2−CH2), 1.51 (d, 4JPH = 2.8 Hz, 15 H, C5Me5),
4
CH2), 1.62 (m, 1 H, Rh−CH2−CH2), 1.58 (d, JPH = 2.7 Hz, 15 H,
C5Me5), 1.28 (dd, 2JPH = 9.8 Hz, 3JRhH = 0.6 Hz, 9 H, PMe3). 13C{1H}
NMR (75.5 MHz, C6D6): δ 144.7 (dm, 1JCF = 242.2 Hz, C2 of C6F5),
139.1 (dm, 1JCF = 248.9 Hz, C4 of C6F5), 137.7 (dm, 1JCF = 250.5 Hz,
C3 of C6F5), 119.9 (tm, 2JCF = 19.5 Hz, C1 of C6F5), 98.3 (dd, 1JRhC
=
4.5 Hz, 2JPC = 3.5 Hz, C5Me5), 30.1 (d, JPC or RhC = 5.7 Hz, RhCH2CH2),
1
1
17.4 (d, JPC = 32.1 Hz, PMe3), 13.6 (dd, JRhC = 25.3 Hz, 2JPC = 14.6
Hz, Rh−CH2−CH2), 10.0 (s, C5Me5). 19F NMR (188.3 MHz, C6D6): δ
−146.3 (m, 2 F, F2), −160.5 (m, 1 F, F4), −163.3 (m, 2 F, F3).
31P{1H} NMR (81.0 MHz, C6D6): δ 3.9 (d, 1JRhP = 159.5 Hz). (+)ESI-
MS (MeCOMe): m/z 194 ([C6F5−C2H3]+), 237 ([Rh(C5Me4CH2)]+),
365 ([Rh(η5-Cp*)I]+), 441 ([Rh(η5-Cp*)I(PMe3)]+), 636 (M+).
[Rh(η5-Cp*)(CH2CH2CF2C6F5)I(PPh3)] (3e′). This was prepared
from [Rh(η5-Cp*)(η2-C2H4)2] (100 mg, 0.34 mmol), PPh3 (90 mg,
0.34 mmol), and ICF2C6F5 (54 μL, 0.34 mmol) in a similar way to 3a′
(method A). After 15 h the resulting suspension was filtered. The
precipitate was identified as [Rh(η5-Cp*)I2(PPh3)] by NMR spec-
troscopy (see below). The filtrate was purified by column
chromatography (silica gel) using Et2O/n-hexane (1:1) as eluent.
The orange fraction (Rf = 0.7) was evaporated to dryness to give an
orange solid (37 mg, 12%). Yellow-orange crystals were obtained from
Et2O/n-pentane at −32 °C. Mp: 141−143 °C. Anal. Calcd for
C37H34F7IPRh: C, 50.94; H, 3.93. Found: C, 50.53; H, 3.57. 1H NMR
(300.1 MHz, CDCl3): δ 7.65−7.10 (br m, 15 H, Ph), 2.92 (m, 1 H,
Rh−CH2−CH2), 2.07 (m, 1 H, Rh−CH2−CH2), 1.59 (m, 1 H, Rh−
CH2−CH2), 1.28 (m, 1 H, Rh−CH2−CH2), 1.51 (d, 4JPH = 2.8 Hz, 15
H, C5Me5). 13C{1H} NMR (75.5 MHz, CDCl3): δ 137.6−131.8 (br m,
4
1.49 (d, JPH = 2.8 Hz, 15 H, C5Me5). 13C{1H} NMR (100.8 MHz,
C6D6): δ 137.5−132.5 (several br m, Ph), 130.1 (s, Ph), 127.9 (d,
JPC = 9.4 Hz, Ph), 126−108 (several overlapping m, CFn), 99.7 (m,
2
C5Me5), 95.5−92.4 (m, CFn), 39.5 (d, JFC = 20.9 Hz, Rh−CH2−
CH2), 39.0 (d, 2JFC = 21.2 Hz, Rh−CH2−CH2), 9.4 (s, C5Me5), 9.3 (s,
C5Me5), 2.5 (dd, 1JRhC = 24.9 Hz, 2JPC = 13.0 Hz, Rh−CH2−CH2), 2.4
1
2
(dd, JRhC = 24.6 Hz, JPC = 13.0 Hz, Rh−CH2−CH2). 19F NMR
(188.3 MHz, C6D6): δ −72.5 (m, 3 F, CFCF3, isomer A), −74.4 (m, 3
F, CFCF3, isomer B), −80.1 (dq, JFF = 4.6 Hz, JFF = 9.0 Hz, 3 F,
5
4
5
4
CF2CF3, isomer A), −80.8 (dq, JFF = 5.8 Hz, JFF = 10.3 Hz, 3 F,
CF2CF3, isomer B), −120.3 (dq, 3JFF = 6.7 Hz, 4JFF = 9.2 Hz, 2 F, CF2,
isomer B), −121.4 (dqd, 1JFF = 292.2 Hz, 3JFF = 6.9 Hz, 4JFF = 11.5 Hz,
1
3
1 F, CF2, isomer A), −123.2 (dqd, JFF = 292.1 Hz, JFF = 6.2 Hz,
4JFF = 9.2 Hz, 1 F, CF2, isomer A), −182.0 (m, 1 F, CF, isomers A and
B). 31P{1H} NMR (162.3 MHz, CDCl3): δ 40.5 (d, 1JRhP = 161.8 Hz),
1
40.0 (d, JRhP = 162.1 Hz). (+)ESI-MS: m/z 499 ([Rh(C5Me4CH2)-
(PPh3)]+), 557, 627 ([Rh(η5-Cp*)I(PPh3)]+), 897 ([M + Na]+), 995
([Rh2(η5-Cp*)2I2(C2H4C4F9)(H2O)]+); exact mass calcd for
C34H34F9INaPRh 897.0246, found 897.0253, Δ = 0.8 ppm.
Ph), 129.8 (br s, Ph), 127.7 (br s, Ph), 99.6 (dd, 1JRhC = 4.6 Hz, 2JPC
=
2
3.1 Hz, C5Me5), 47.4 (t, JFC = 21.6 Hz, Rh−CH2−CH2), 9.3 (s,
C5Me5), 3.1 (ddd, 1JRhC = 24.8 Hz, 2JPC = 13.4 Hz, 3JFC = 2.6 Hz, Rh−
CH2−CH2). The signals of the CF2C6F5 carbons could not be assigned
because of their low intensity and overlap with phenylic signals. 19F
NMR (188.3 MHz, CDCl3): δ −84.6 (dm, 2JFF = 255.3 Hz, 1 F, CF2),
[Rh(η5-Cp*){CH2CH2C(CF3)3}I(PMe3)] (3c). Method A. This
was prepared in the same way as 3a starting from [Rh(η5-Cp*)-
(η2-C2H4)2] (122 mg, 0.41 mmol), PMe3 (0.45 mmol), and IC(CF3)3
(150 mg, 0.43 mmol). The volatiles were removed under vacuum, and
the residue was extracted with n-pentane (25 mL). Evaporation of the
solvent gave an orange solid (230 mg, 80%).
2
−95.4 (dm, JFF = 257.6 Hz, 1 F, CF2), −140.6 (m, 2 F, F2 of C6F5),
2
−152.9 (t, 1 F, JFF = 21.1 Hz, F4 of C6F5), −161.9 (m, 2 F, F3 of
1
C6F5). 31P{1H} NMR (81.0 MHz, CDCl3): δ 41.6 (d, JRhP = 161.8
Method B. IC(CF3)3 (185 mg, 0.52 mmol) was added to a solu-
tion of [Rh(η5-Cp*)(η2-C2H4)2] (111 mg, 0.38 mmol) in n-pentane
(4 mL). After stirring for 20 h at room temperature, the solvent was
removed under vacuum, and the dark red residue was dissolved in
toluene (5 mL). Then PMe3 (0.37 mmol) was added, and the solution
was stirred for 3 h. The volatiles were removed under vacuum, and
the residue was extracted with n-pentane (40 mL). The extract was
evaporated to dryness, and the residue was chromatographed on a
silica gel column, eluting with Et2O/n-hexane (1:1). The collected
fraction (Rf = 0.5) was evaporated to dryness to give an orange solid
(135 mg, 52%). X-ray quality single crystals were obtained by slow
evaporation of an n-hexane solution. Mp: 135−137 °C. Anal. Calcd for
C19H28F9IPRh: C, 33.16; H, 4.10. Found: C, 33.22; H, 4.16. 1H NMR
(400.9 MHz, C6D6): δ 3.23 (m, 1 H, Rh−CH2−CH2), 2.30 (m, 1 H,
Hz). (+)ESI-MS: m/z 496, 499 ([Rh(C5Me4CH2)(PPh3)]+), 537, 565,
627 ([Rh(η5-Cp*)I(PMe3)]+), 721, 745 ([Rh(η5-Cp*)-
(C2H4CF2C6F5)(PMe3)]+), 911 ([M + K]+); exact mass calcd for
C37H34F7IKPRh 911.0023, found 911.0000, Δ = 2.5 ppm. [Rh(η5-
Cp*)I2(PPh3)]: 1H NMR (300.1 MHz, CDCl3): δ 7.82−7.20 (several
br m, 15 H, Ph), 1.76 (d, 3JRhH = 3.3 Hz, 15 H, C5Me5). 31P{1H} NMR
(121.5 MHz, CDCl3): δ 27.8 (d, 1JRhP = 148.7 Hz). These data are in
agreement with those of a sample prepared by a reported method.69,70
[Rh(η5-Cp*)(CF2C6F5)I(PMe3)] (4e). This was prepared from
[Rh(η5-Cp*)(η2-C2H4)2] (137 mg, 0.47 mmol), PMe3 (0.56 mmol),
and ICF2C6F5 (76 μL, 0.48 mmol) in a similar way to 3a (method A).
Column chromatography (silica gel) using Et2O/n-hexane (3:1) as eluent
gave an orange fraction (Rf = 0.6), which was evaporated to dryness to
Rh−CH2−CH2), 1.76−1.65 (m, 2 H, Rh−CH2−CH2), 1.45 (d, 4JPH
=
1
give an orange solid (165 mg, 47%). The H, 19F, and 31P{1H} NMR
data of this compound agreed with those previously reported.22
Reaction of [Rh(η5-Cp*)(η2-C2H4)(PMe3)] with InC3F7. PMe3
(0.054 mmol) was added to a solution of [Rh(η5-Cp*)(η2-C2H4)2]
(16 mg, 0.054 mmol) in C6D6 (0.5 mL) in an NMR tube. The tube
2
3
3.0 Hz, 15 H, C5Me5), 1.11 (dd, JPH = 9.9 Hz, JRhH = 0.9 Hz, 9 H,
1
PMe3). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 122.7 (qm, JCF
=
287.6 Hz, CF3), 98.8 (dd, 1JRhC = 4.8 Hz, 2JPC = 3.2 Hz, C5Me5), 60.7
2
(decaplet, JCF = 24.2 Hz, CCF3), 36.6 (d, JPC or RhC = 3.6 Hz, Rh−
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−
4
was closed and heated at 120 °C for 20 h. Then, it was cooled to room
temperature, and InC3F7 (8 μL, 0.054 mmol) was added. After 24 h,
1H, 19F, and 31P{1H} NMR spectra of the resulting dark red-brown
solution were measured. [Rh(η5-Cp*)(nC3F7)I(PMe3)] (4f)21 and
[Rh(η5-Cp*)I2(PMe3)]69,70 were the main reaction products,
accounting respectively for 40% and 27% of the mixture (the ratio is
based on the integration of the 31P{1H} NMR spectra of the mixture).
Their NMR data were in agreement with those previously reported. 4f:
1H NMR (300.1 MHz, C6D6) δ 1.50 (d, 3JRhH = 3.3 Hz, 15 H, C5Me5),
13.8 (very br s, 1 H, Fn+1Hn ), 1.94 (t, JPH = 3.2 Hz, 15 H, C5Me5),
1
−
1.76 (m, 9 H, PMe3); (−90 °C) δ 16.2 (br t, JFH = 121 Hz, HF2 ),
−
13.7 (br d, 1JFH = 352 Hz, H2F3 ), 1.83 (br s, C5Me5), 1.64 (br s, 9 H,
PMe3). 19F NMR (282.4 MHz, CD2Cl2, 21 °C): δ −128.2 (very br s,
SiF62−), −165.4 (very br s, Fn+1Hn−); (−90 °C) δ −128.5 (br s,
SiF62−), −146.6 (br t, 1JFH = 131.5 Hz, [FHFHF]−), −149.5 (br d, 1JFH
=
123.6 Hz, [FHF]−), −174.3 (br dd, JFH = 350.0 Hz, JFF = 130.9 Hz,
1
2
[FHFHF]−). 31P{1H} NMR (81.0 MHz, CD2Cl2): δ 1.2 (d, JRhP
=
1
131.9 Hz). (+)ESI-MS: m/z 517 ([Rh(η5-Cp*)I(PMe3)2]+); exact mass
calcd for C16H33IP2Rh 517.0152, found 517.0171, Δ = 3.7 ppm.
[Rh(η5-Cp)(nC4F9)I(PMe3)] (5). A solution of [Rh(η5-Cp)(η2-C2H4)-
(PMe3)] (290 mg, 1.07 mmol) in n-pentane (10 mL) was treated with
InC4F9 (0.19 mL, 1.08 mmol). The mixture was stirred for 10 min.
An orange solid precipitated, which was filtered, washed with n-pentane
(2 × 10 mL), and dried under vacuum (302 mg, 48%). Mp: 196−
198 °C. Anal. Calcd for C12H14F9IPRh: C, 24.43; H, 2.39. Found: C,
2
1.24 (d, JPH = 10.6 Hz, 9 H, PMe3). 19F NMR (282.4 MHz, C6D6):
δ −66.1 (AB d, 2JFF = 272.4 Hz, 1 F, RhCF2), −68.7 (AB d, 2JFF = 269.3
Hz, 1 F, RhCF2), −78.5 (t, 3JFF = 11.3 Hz, 3 F, CF3), −113.3 (AB d, 2JFF
=
2
279.7 Hz, 1 F, CF2CF3), −114.9 (AB d, JFF = 279.1 Hz, 1 F, CF2CF3).
1
31P{1H} NMR (121.5 MHz, C6D6): δ 2.7 (dm, JRhP = 150.7 Hz).
[Rh(η5-Cp*)I2(PMe3)]: 1H NMR (300.1 MHz, C6D6): δ 1.58 (d,
2
3JRhH = 3.4 Hz, 15 H, C5Me5), 1.48 (d, JPH = 10.1 Hz, 9 H, PMe3).
1
2
24.31; H, 2.44. H NMR (200.1 MHz, CDCl3): δ 5.52 (d, JRhH = 1.5
1
31P{1H} NMR (121.5 MHz, C6D6): δ −2.0 (d, JRhP = 138.2 Hz).
Hz, 5 H, C5H5), 1.81 (d, JPH = 11.4 Hz, 9 H, PMe3)1. 13C{1H} NMR
2
[Rh(η5-Cp*)(nC4F9)I(PMe3)] (4g). This was prepared from
[Rh(η5-Cp*)(η2-C2H4)2] (150 mg, 0.51 mmol), PMe3 (0.61 mmol),
and InC4F9 (90 μL, 0.51 mmol) in a similar way to 3a (method A).
Column chromatography (silica gel) using Et2O as eluent gave an
orange fraction (Rf = 0.95), which was evaporated to dryness to give an
orange oil (40 mg, 12%). X-ray quality single crystals were obtained by
slow evaporation of a toluene solution. Mp: 153−156 °C. Anal. Calcd
(100.8 MHz, C6D6): δ 135.3 (m, CF2), 117.9 (qt, JFC = 288.1 Hz,
2JFC = 34.1 Hz, CF3), 114.9−106.1 (two overlapped multiplets, 2 CF2),
90.4 (s, C5H5), 21.0 (d, 1JPC = 35.6 Hz, PMe3). 19F NMR (188.3 MHz,
2
CDCl3): δ −54.8 (AB d, JFF = 254.2 Hz, 1 F, CαFA), −66.5 (AB d,
2JFF = 257.0 Hz, 1 F, CαFB), −81.7 (br s, 3 F, CF3), −110.0 (AB d, 2JFF
=
281.9 Hz, 1 F, CβFA), −111.8 (AB d, 2JFF = 279.6 Hz, 1 F, CβFB), −125.7
(m, 2 F, CγF2). 31P{1H} NMR (81.0 MHz, C6D6): δ 9.8 (dddd, JRhP
=
1
1
for C17H24F9IPRh: C, 30.93; H, 3.66. Found: C, 31.01; H, 3.36. H
146.0 Hz, JPF = 21.9, 9.5, and 6.4 Hz).
4
NMR (400.9 MHz, C6D6): δ 1.49 (d, JPH = 2.8 Hz, 15 H, C5Me5),
[Rh(η5-Cp*){CH2CH2CF(CF3)2}(CNXy)(PPh3)](OTf) (6). AgOTf
(36 mg, 0.14 mmol) was added to a solution of 3a′ (116 mg,
0.14 mmol) in THF (9 mL). The mixture was stirred for 2 h at room
temperature and evaporated to dryness. The residue was stirred with
CH2Cl2 (9 mL), and the suspension was filtered. XyNC (19 mg,
0.14 mmol) was added to the resulting orange solution. After stirring
for 5 h at room temperature, the resulting light orange solution was
evaporated to dryness. The residue was washed with Et2O (3 × 5 mL)
and dried under vacuum to give 5 as a yellowish-brown solid (106 mg,
87%). Anal. Calcd for C43H43F10NO3PRhS: C, 52.82; H, 4.43; N, 1.43;
S, 3.28. Found: C, 52.53; H, 4.50; N, 1.51; S, 3.24. IR (Nujol, cm−1):
ν(CN) 2133. 1H NMR (400.9 MHz, CD2Cl2): δ 7.59 (m, 3 H, H4
of Ph), 7.51 (m, 6 H, H3 of Ph), 7.31 (m, 7 H, H2 of Ph and H4 of
2
1.23 (d, JPH = 10.5 Hz, 9 H, PMe3). 13C{1H} NMR (75.5 MHz,
1
2
C6D6): δ 101.5 (dd, JRhC = 4.5 Hz, JPC = 2.9 Hz, C5Me5), 19.0 (d,
1JPC = 33.3 Hz, PMe3), 10.4 (s, C5Me5). The signals corresponding to
the carbons of the C4F9 group were not observed. 19F NMR (188.3
n
MHz, C6D6): δ −66.2 (AB d, 2JFF = 272.1 Hz, 1 F, RhCF2), −68.3 (AB
2
d, JFF = 273.0 Hz, 1 F, RhCF2), −80.8 (s, 3 F, CF3), −110.3 (AB d,
2JFF = 285.4 Hz, 1 F, CβF2), −111.7 (AB d, 2JFF = 285.4 Hz, 1 F, CβF2),
−124.6 (m, 2 F, CγF2). 31P{1H} NMR (81.0 MHz, C6D6): δ 2.7 (dm,
1JRhP = 150.5 Hz).
[Rh(η5-Cp*)(CFCF2)I(PMe3)] (4h). This was prepared from
[Rh(η5-Cp*)(η2-C2H4)2] (157 mg, 0.53 mmol), PMe3 (0.64 mmol),
and ICFCF2 (53 μL, 0.56 mmol) in a similar way to 3a (method A).
Column chromatography (silica gel) using Et2O/n-hexane (3:1) as
eluent gave an orange fraction (Rf = 0.6), which was evaporated to
dryness to give an orange solid (40 mg, 14%). Mp: 132−135 °C. Anal.
Calcd for C15H24F3IPRh: C, 34.51; H, 4.63. Found: C, 34.21; H, 4.68.
1H NMR (300.1 MHz, C6D6): δ 1.53 (d, 4JPH = 2.9 Hz, 15 H, C5Me5),
3
Xy), 7.17 (d, JHH = 7.6 Hz, 2 H, H3 of Xy), 2.37−2.22 (m, 2 H,
CH24CF), 2.18 (s, 6 H, Me of Xy), 1.80−1.57 (m, 2 H, RhCH2), 1.67
(d, JPH = 2.9 Hz, 15 H, C5Me5). 13C{1H} NMR (100.8 MHz,
1
2
CDCl3): δ 151.7 (dd, JRhC = 72.1 Hz, JPC = 25.2 Hz, CN), 135.2
(s, C2 of Xy), 133.3 (d, 2JPC = 9.7 Hz, C2 or C3 of Ph), 132.1 (s, C4 of
Ph), 130.4 (s, C4 of Xy), 129.3 (br d, 2JPC = 48.2 Hz, C1 of Ph), 129.3
(d, 2JPC = 10.5 Hz, C3 or C2 of Ph), 128.8 (s, C3 of Xy), 126.5 (s, C−
2
1.30 (d, JPH = 10.8 Hz, 9 H, PMe3). 13C{1H} NMR (75.5 MHz,
C6D6): δ 160.2 (ddd, 1JCF = 311.7 and 259.8 Hz, 2JCF = 47.4 Hz, CF
1
2
CF2), 100.1 (dd, 1JRhC = 4.5 Hz, 2JPC = 3.0 Hz, C5Me5), 18.3 (d, 1JPC
=
N), 120.81 (qd, JFC = 286.6 Hz, JFC = 28.2 Hz, CF3), 120.74 (qd,
1JFC = 286.7 Hz, 2JFC = 28.1 Hz, CF3), 104.9 (d, 1JRhC = 2.1 Hz, 2JPC
=
34.3 Hz, PMe3), 10.0 (s, C5Me5). The signal corresponding to the
CFCF2 carbon was not observed. 19F NMR (282.4 MHz, C6D6):
δ −90.4 (dd, 2JFF = 93.9 Hz, 3JFF cis = 38.8 Hz, RhCCF trans to Rh),
−121.9 (dd, 2JFF = 93.7 Hz, 3JFF trans = 109.4 Hz, RhCCF cis to Rh),
3.9 Hz, C5Me5), 91.0 (d of septuplets, 1JFC = 201.7 Hz, 2JFC = 31.0 Hz,
CF), 35.3 (d, 2JFC = 21.5 Hz, CH2CF), 18.8 (s, MeAr), 9.3 (s, C5Me5),
4.8 (dd, JRhC = 23.4 Hz, JPC = 9.4 Hz, RhCH2). 19F NMR (188.3
1
2
MHz, CDCl3): δ −75.4 (dq, 3JFF = 4JFF = 8.6 Hz, CF3CF), −76.9 (dq,
−140.4 (ddt, 3JFF trans = 110.3 Hz, 3JFF cis = 3JPF = 36.9 Hz, 2JRhF = 15.0
3JFF
=
4JFF = 8.6 Hz, CF3CF), −79.0 (s, OTf), −184.9 (m, CF).
1
Hz, RhCFC). 31P{1H} NMR (81.0 MHz, C6D6): δ 6.0 (dd, JRhP
=
31P{1H} NMR (81.0 MHz, CDCl3): δ 43.5 (d, JRhP = 131.0 Hz).
(+)ESI-MS: m/z 828 (M+); exact mass calcd for C42H43F7NPRh
828.2071, found 828.2087, Δ = 1.9 ppm.
1
3
140.8 Hz, JPF = 39.9 Hz).
Reaction of [Rh(η5-Cp*)(η2-C2H4)(PMe3)] with ICF(CF3)-
CF2CF3. PMe3 (0.07 mmol) was added to a solution of [Rh(η5-
Cp*)(η2-C2H4)2] (21 mg, 0.071 mmol) in C6D6 (0.5 mL) in an NMR
tube. The tube was closed and heated at 120 °C until the conversion
of the starting complex into [Rh(η5-Cp*)(η2-C2H4)(PMe3)] was
complete according to the 1H and 31P{1H} NMR spectra (24 h).
Then, ICF(CF3)CF2CF3 was added (12 μL, 0.073 mmol). A fast color
change from yellow to dark red was observed. After 24 h at room
temperature, a crystalline orange-red solid precipitated. After
measuring NMR spectra, the solution was removed and the solid
was washed with toluene (3 × 0.5 mL) and Et2O (3 × 1 mL) and
dried under vacuum. In the 19F NMR spectrum of the solution, the
main signals corresponded to trans- and cis-octafluoro-2-butene:71 19F
NMR (188.3 MHz, C6D6): δ (trans isomer) −69.1 (m, 6 F, CF3),
−159.8 (m, 2 F, CF); (cis isomer) −66.7 (m, 6 F, CF3), −141.6 (m, 2
[Rh(η5-Cp*){C(O)CH2CH2CF(CF3)2}(CO)(PPh3)]OTf (7). AgOTf
(32 mg, 0.12 mmol) was added to a solution of 3a′ (100 mg,
0.12 mmol) in THF (10 mL), and the mixture was stirred at room
temperature for 2 h and evaporated to dryness. The residue was
extracted with CH2Cl2 (8 mL), and the extract was filtered. CO was
bubbled through the extract for 3 min. Then, the reaction tube was
closed and the solution was stirred for 48 h at room temperature. A
small amount of black precipitate was removed by filtration, and the
filtrate was evaporated to dryness to give a dark yellow solid, which
was washed with n-pentane (3 × 3 mL) to give crude 7 (73 mg, 69%).
Yellow, analytically pure crystals were obtained by liquid diffusion of
n-pentane into a CH2Cl2 solution. Mp: 144−146 °C. Anal. Calcd for
C36H34F10O5PRhS: C, 47.91; H, 3.80; S, 3.55. Found: C, 48.23; H,
3.79; S, 3.35. IR (Nujol, cm−1): ν(CO) 2043 (CO), 1682 (CO).
1
F, CF). Data of the solid: H NMR (300.1 MHz, CD2Cl2, 21 °C): δ
1296
dx.doi.org/10.1021/om2009588 | Organometallics 2012, 31, 1287−1299

Organometallics
Article
Table 2. Crystallographic Data
1a·C6D6
C36H38D6F14I2Rh2
1b
3c
4g
7
8
formula
cryst size (mm3)
cryst syst
space group
a (Å)
C32H38F18I2Rh2
C19H28F9IPRh
C17H24F9IPRh
C36H34F10O5PRhS
C18H29BF4INPRh
0.20 × 0.15 × 0.04 0.17 × 0.11 × 0.10 0.18 × 0.12 × 0.08 0.26 × 0.18 × 0.04 0.21 × 0.19 × 0.08 0.4 × 0.3 × 0.2
triclinic
monoclinic
P21/n
monoclinic
P21/c
monoclinic
P21/c
monoclinic
P21/c
monoclinic
P21/c
P1
̅
12.4747(4)
13.3277(5)
15.0019(5)
70.372(2)
66.215(2)
66.821(2)
2051.06(12)
2
14.6027(14)
8.1396(8)
16.9438(16)
90
17.4942(15)
10.7840(9)
13.5254(12)
90
9.4279(4)
13.1022(5)
18.0704(7)
90
16.6976(11)
13.5697(9)
16.8812(11)
90
8.1288(3)
21.5156(6)
12.9148(4)
90
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
V (Å3)
103.877(2)
90
107.105(2)
90
99.886(2)
90
103.331(2)
90
95.866(3)
90
1955.2(3)
2
2438.8(4)
4
2199.02(15)
4
3721.9(4)
4
2246.92(13)
4
Z
ρcalcd (g cm−3
)
1.956
2.080
1.874
1.994
1.611
1.794
F000
μ (mm−1
1164
1176
1344
1280
1824
1192
)
2.399
2.533
2.104
2.329
0.650
2.24
transmns
0.9101−0.6175
1.52−28.24
23 839
0.7858−0.5468
2.11−25.68
19 522
0.8497−0.6499
2.25−28.61
16 032
0.9126−0.6541
1.93−28.09
24 816
0.9499−0.8049
1.95−28.74
58 112
1.000−0.842
2.52−31.0
101 180
0.037
θ range (deg)
reflns collected
Rint
0.0256
0.0492
0.0254
0.0223
0.0280
data/restraints/params
GOF
9196/12/493
1.057
3703/0/249
1.092
5737/0/288
1.192
5074/0/270
1.038
9096/13/485
1.064
7156/0/252
1.11
a
R1
0.0355
0.0433
0.0371
0.0190
0.0470
0.0296
b
wR2
0.0781
0.1081
0.0739
0.0462
0.1149
0.0699
largest diff peak, hole (e Å−3
)
1.049, −0.862
2.951, −0.745
0.921, −0.464
0.574, −0.450
1.280, −1.318
2.48, −1.13
a
b
R1 = ∑||Fo| − |Fc||/∑|Fo| for reflections with I > 2σ(I). wR2 = [∑[w(Fo2 − Fc2)2]/∑[w(Fo )2]0.5 for all reflections; w−1 = σ2(F2) + (aP)2 + bP,
2
where P = (2Fc2 + Fo )/3 and a and b are constants set by the program.
2
H, 4.98; N, 2.28. 1H NMR (400.9 MHz, CD2Cl2): δ 8.86 (br m, 2 H,
H2 of py), 7.97 (m, 1 H, H4 of py), 7.55 (m, 2 H, H3 of py), 1.75 (d,
4JPH = 3.4 Hz, 15 H, C5Me5), 1.66 (dd, 2JPH = 10.7 Hz, 3JRhH = 0.5 Hz,
9 H, PMe3). 13C{1H} NMR (100.8 MHz, CD2Cl2): δ 156.9 (br s, C2
of py), 139.9 (s, C4 of py), 127.9 (s, C3 of py), 100.9 (dd, 1JRhC = 6.2
1H NMR (200.1 MHz, CDCl3): δ 7.64−7.52 (m, 9 H, H3 and H4 of
Ph), 7.43−7.34 (m, 6 H, H2 of Ph), 2.93−2.76 (m, 1 H, CH2), 2.46−
2.29 (m, 1 H, CH2), 2.18−1.99 (m, 1 H, CH2), 1.78−1.64 (m, 1 H,
4
CH2), 1.72 (d, JPH = 3.2 Hz, 15 H, C5Me5). 13C{1H} NMR (75.5
1
2
MHz, CDCl3): δ 229.5 (dd, JRhC = 27.1 Hz, JPC = 9.5 Hz, CO),
190.0 (dd, 1JRhC = 76.2, 2JPC = 20.1, CO), 133.4 (br d, JPC = 9.9 Hz,
C2 of Ph), 132.7 (d, JPC = 2.2 Hz, C4 of Ph), 129.7 (d, JPC = 11.1 Hz,
2
1
Hz, JPC = 2.6 Hz, C5Me5), 16.9 (d, JPC = 33.9 Hz, PMe3), 10.2 (s,
C5Me5). 19F NMR (188.3 MHz, CD2Cl2): δ −152.7 (s, 10BF4), −152.6
1
(s, 11BF4). 31P{1H} NMR (100.8 MHz, CD2Cl2): δ 2.0 (d, JRhP
=
1
2
C3 of Ph), 120.7 (qd, JFC = 286.8 Hz, JFC = 27.9 Hz, CF3), 109.6
1
2
137.7 Hz).
(dd, JRhC = 3.5 Hz, JPC = 1.2 Hz, C5Me5), 90.8 (d of septuplets,
1JFC = 204.0 Hz, 2JFC = 32.2 Hz, CF), 54.7 (s, CH2), 24.3 (d, 2JFC = 20.7
Hz, CH2CF), 9.6 (s, C5Me5). The signal of the C1 of Ph could not be
located. 19F NMR (282.4 MHz, CDCl3): δ −76.9 (m, CF3CF), −78.6
(s, OTf), −185.9 (m, CF). 31P{1H} NMR (81.1 MHz, CDCl3): δ 31.6
Anion Trapping Experiments. Typical Procedure. Complex
[Rh(η5-Cp*)(η2-C2H4)(PMe3)] was generated in situ by heating
[Rh(η5-Cp*)(η2-C2H4)2] (15 mg, 0.051 mmol) and PMe3 (55 μL of a
1 M toluene solution, 0.055 mmol) in C6D6 or D8-toluene (0.5 mL) at
120 °C for 24 h in an NMR tube. Then, CH3OD and IRF were
consecutively added. After 1 h, the NMR spectra of the dark red
solution were measured. The NMR data of the detected species (DRF
or HRF; RF = CF(CF3)2,65,72 C(CF3)3,72,73 nC4F9,71,72 and C6F574) are
given in the Supporting Information.
X-ray Crystallography. Complexes 1a, 1b, 3c, 4g, and 7 were
measured on a Bruker Smart APEX, and 8 was measured on an Oxford
Diffraction Xcalibur S diffractometer. Data were collected using mono-
chromated Mo Kα radiation in ω-scan mode at 100 K. Absorption
corrections were applied on the basis of multiscans (Program SADABS
for complexes 1a, 1b, 3c, 4g, and 7 and CrysAlis RED for 8). All struc-
tures were refined anisotropically on F2. The methyl groups were
refined using rigid groups (AFIX 137), and the other hydrogens were
refined using a riding model. Special features and exceptions: For
complex 1a, two CF3 groups are disordered over two positions; for
complex 7, all the CF3 groups are disordered over two positions.
(d, JRhP = 136.9 Hz). (+)ESI-MS: m/z 725 ([Rh(η5-Cp*)(PPh3)-
1
(COCH2CH2C3F7)]+), 753 ([Rh(η5-Cp*)(PPh3)(COCH2-
CH2C3F7)]+); exact mass calcd for M+ (C35H34O2PF7Rh) 753.1234;
found 753.1243 (Δ = 1.2 ppm).
[Rh(η5-Cp*)I(py)(PMe3)](BF4) (8). Method A. A solution of
[Rh(η5-Cp*)(η2-C2H4)2] (154 mg, 0.52 mmol) and PMe3 (0.52 mmol)
in toluene (4 mL) was stirred at 120 °C for 24 h in a Carius tube. The
resulting solution of [Rh(η5-Cp*)(η2-C2H4)(PMe3)] was cooled to
room temperature, and [I(py)2](BF4) (195 mg, 0.52 mmol) was
added. The mixture was vigorously stirred for 24 h. An orange solid
precipitated, which was decanted, washed with Et2O (3 × 5 mL), and
dried under vacuum (202 mg, 64%).
Method B. AgBF4 (72 mg, 0.37 mmol) was added to a solution of
[Rh(η5-Cp*)I2(PMe3)] (208 mg, 0.37 mmol) in THF (10 mL) After
stirring for 30 min in the dark, pyridine (30 μL, 0.37 mmol) was added.
The suspension was stirred for 30 min more and then evaporated to
dryness. The residue was extracted with CH2Cl2 (10 mL). The suspen-
sion was filtered, and the filtrate was evaporated to dryness under
vacuum. On addition of Et2O (15 mL), an orange solid precipitated,
which was filtered, washed with n-pentane (5 mL), and dried under
vacuum (133 mg, 60%). X-ray quality single crystals were obtained
by liquid diffusion (CH2Cl2/n-hexane). Mp: 218−220 °C. Anal. Calcd
for C18H29BF4INPRh: C, 35.62; H, 4.82; N, 2.31. Found: C, 35.78;
ASSOCIATED CONTENT
■
S
* Supporting Information
Variable-temperature 1H and 19F NMR spectra of [Rh(η5-Cp*)-
I(PMe3)2]Fn+1Hn. NMR data of the DRF or HRF species detected
in the anion trapping experiments. Crystallographic information in
1297
dx.doi.org/10.1021/om2009588 | Organometallics 2012, 31, 1287−1299

Organometallics
Article
(33) Yuan, J.; Hughes, R. P.; Rheingold, A. L. Organometallics 2011,
30, 1744.
(34) Moseley, K.; Kang, J. W.; Maitlis, P. M. J. Chem. Soc. A 1970,
CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
2875.
AUTHOR INFORMATION
Corresponding Author
*E-mail: jgr@um.es, http://www.um.es/gqo/.
■
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ACKNOWLEDGMENTS
We thank the Spanish Ministerio de Ciencia e Innovacion
(grant CTQ2007-60808/BQU, with FEDER support) and
Fundacion Seneca (grants 02992/PI/05 and 04539/GERM/06)
́ ́
for financial support.
■
́
DEDICATION
■
†Dedicated to Prof. Juan Fornies
́
on the occasion of his retirement.
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