Facile single or double C-H bond activation on a Cp ligand promoted by the presence of alkynylphosphine ligands

Article abstract of DOI:10.1021/om800867h

The behavior of the cationic alkynylphosphine complex [Rh(η ⁵-Cp^*;)a(PPh₂C?CPh) ₂](CF₃SC₃) (1) under thermal or basic conditions is described. Complex 1 rearranges thermally (toluene, reflu

Full text of DOI:10.1021/om800867h

312
Organometallics 2009, 28, 312–320
Facile Single or Double C-H Bond Activation on a Cp* Ligand
Promoted by the Presence of Alkynylphosphine Ligands
Mar´ıa Bernechea, Jesu´s R. Berenguer,* Elena Lalinde,* and Javier Torroba
Departamento de Qu´ımica-Grupo de S´ıntesis Qu´ımica de La Rioja, UA-CSIC, UniVersidad de La Rioja,
26006 Logron˜o, Spain
ReceiVed September 5, 2008
The behavior of the cationic alkynylphosphine complex [Rh(η5-Cp*)Cl(PPh2Ct CPh)2](CF3SO3) (1)
under thermal or basic conditions is described. Complex 1 rearranges thermally (toluene, reflux) to generate
a solution from which a mixture formed by 1, the monohydroalkylated derivative [Rh{κP:η5-C5Me4-
(CH2CPhdCHPPh2)}Cl(PPh2Ct CPh)](CF3SO3) (2), and the symmetrical 1,2 -dihydroalkylated derivative
[Rh{κ2PP′:η5-C5Me3-1,2-(CH2CPhdCHPPh2)2}Cl](CF3SO3) (3′) (∼30:60:10, respectively) can be isolated.
From this mixture, compounds 1 and 2 cocrystallize together, giving rise to a solid solution, as has been
confirmed by X-ray crystallography. In contrast, treatment of [Rh(η5-Cp*)Cl(PPh2Ct CPh)2](CF3SO3)
(1) with Na2CO3 evolves with the formation of the new asymmetrical 1,2- and 1,3-dihydroactivated isomers
[Rh{κ2PP′:η5-1,2-(PPh2CH2CPhdCH)C5Me3(CH2CPhdCHPPh2)}Cl](CF3SO3) (3, X-ray) and [Rh{κ2PP′:
η5-1,3-(PPh2CH2CPhdCH)C5Me3(CH2CPhdCHPPh2)}Cl](CF3SO3) (4), generated by the occurrence of
a simultaneous 1,2- or 1,3-double C-H bond addition to the triple bonds, together with an additional
isomerization process. A detailed study of this reaction (reflux or room temperature) provides evidence
that these asymmetrical deactivated complexes (3, 4) are generated by initial formation of the corresponding
symmetrical 1,2- and 1,3-dihydroalkylated species 3′ and 4′, respectively.
tridentate trimethyl24-28) cyclopentadienylphosphine ligands,
mainly due to their implication in homogeneous catalytic
Introduction
processes.1,12,15,16,18,19,21,28 Two different synthetic approaches
have been used for the preparation of complexes containing
these ligands: (i) prior synthesis of the hybrid ligand followed
by coordination to the metal,16,17,19,28 and (ii) intramolecular
coupling of both the previously coordinated phosphine and
cyclopentadienyl groups.15,18,20–23 The first strategy normally
leads to poor overall yields, as it involves multiple steps based
on classical organic methods, while the second approach
provides a method of overcoming this problem.
On the other hand, alkynylphosphines have been shown to
be a very useful type of ligand with excellent promise in
coordination chemistry,29 mainly due to their ability to coor-
dinate via the phosphorus atom and/or the Ct C moiety, thus
favoring the formation of a rich variety of homo- and het-
In recent years considerable attention has been focused on
the synthesis of functionalized cyclopentadienyl ligands
C5Me4X,1-14 where X is a pendant arm bearing a functionality
which can hold or orient potential reactants or can chelate to
the metal center. In this area, particular interest has been devoted
to hemilabile bidentate tetramethyl12,15-23 (or the less abundant
* To whom correspondence should be addressed. E-mail: elena.lalinde@
unirioja.es (E.L.); jesus.berenguer@unirioja.es (J.R.B.).
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10.1021/om800867h CCC: $40.75
2009 American Chemical Society
Publication on Web 12/15/2008

C-H Bond ActiVation on a Cp* Ligand
Organometallics, Vol. 28, No. 1, 2009 313
eropolynuclear species.29–47 Furthermore, they present a varied
and rich chemistry related to several processes, among which
are (i) the phosphorus-carbon bond cleavage to generate
phosphido and alkynyl fragments via interaction with metal
carbonyl clusters,29,48-50 (ii) their possible engagement in
characteristic insertion reactions of the triple bonds35,51-55 or
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and also (iii) intermolecular coupling of the alkynyl moieties
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alkynylphosphines, having reported the formation of novel
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diphosphine ligands, activated by complexation of a “cis-
Pt(C6F5)2” fragment,35,52 under thermal or photochemical con-
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Following from this work, and with the aim of studying the
influence of the geometry and the metal center in these types of
processes, we have tried to induce thermally similar coupling
reactions in the cationic rhodium(III) complex [Rh(η5-Cp*)
Cl(PPh2Ct CPh)2](TfO). Nevertheless, instead of a coupling
process, the reaction progresses through the unexpected activation
of one or two C-H bonds on the Cp* ligand and their formal
addition to the triple bond of the phosphine ligands, giving rise to
the formation of novel cyclopentadienyl-ene-phosphine ligands,
which has no precedent in the literature. The C-H bond activation
of η5-coordinated Cp* ligands constitutes an important reaction,
which affords tetramethylfulvene compounds14,67-73 or species with
functionalized cyclopentadienyl ligands.5,7,9,11,12,15,18,21,22,24,67,71,73,74
As this process is commonly activated by heat7,9,15,67,69,70 or by
treatment with base,3,5,24,68,73,74 we have also examined the behavior
of [Rh(η5-Cp*)Cl(PPh2Ct CPh)2](CF3SO3) (1) in tetrahydrofuran
in the presence of a weak base such as Na2CO3.
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Synthetic Studies. The results of the behavior of the complex
[Rh(η5-Cp*)Cl(PPh2Ct CPh)2](CF3SO3) (1) under thermal or
basic conditions are summarized in Scheme 1. As it is shown,
the treatment of [Rh(η5-Cp*)Cl(PPh2Ct CPh)2](CF3SO3) (1)
with a weak base such as Na2CO3 (Scheme 1, step i) in
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CHPPh2)}Cl](CF3SO3) (3). The complex is obtained impure with
a minute amount of the corresponding symmetrical 1,2-isomer
[Rh{κ2PP′:η5-C5Me3-1,2-(CH2CPhdCHPPh2)2}Cl](CF3SO3)
(3′), which can be eliminated by crystallization from acetone/
hexane to give pure 3 as an orange solid (see the Experimental
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complex 3 involves a double-hydroalkylation reaction (formation
of 3′), together with an additional isomerization process, leading
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314 Organometallics, Vol. 28, No. 1, 2009
Bernechea et al.
Scheme 1
donor, as has been confirmed by an X-ray crystallographic study
(see below). As far as we know, only two other examples have
been reported where the C-H bond activation on a Cp* ligand
gives rise to a chelating κP:η5 ligand presenting a vinylic chain
between the phosphorus atom and the cyclopentadienyl group.75,76
In contrast, when complex 1 is refluxed in toluene in the
absence of base (8 h, Scheme 1, step ii), the resulting solution
is found to be a mixture of the precursor 1 with the monohy-
droalkylated derivative [Rh{κP:η5-C5Me4(CH2CPhdCHPPh2)}-
Cl(PPh2Ct CPh)](CF3SO3) (2) and the symmetrical 1,2- and
1,3-dihydroalkylated complexes 3′ and [Rh{κ2PP′:η5-C5Me3-
1,3-(CH2CPhdCHPPh2)2}Cl](CF3SO3) (4′) (31P{1H} NMR, ap-
proximate molar ratio 25:57:12:6 for 1:2:3′:4′). The usual
workup of the solution afforded a solid mixture of 1 and 2,
together with a small quantity of 3′ (Scheme 1, step ii,
approximate molar ratio 30:60:10 for 1:2:3′). Unfortunately,
chromatographic methods failed to produce any pure product
from the mixture, and all attempts at recrystallization in different
solvents did not change the relative amounts of these three
complexes. Slow diffusion of hexane into a solution of the mixture
of 1, 2, and 3′ in acetone afforded orange monocrystals suitable
for X-ray diffraction. In spite of the fact that all the crystals had
the same appearance under the microscope, the spectroscopic data
of their solutions still revealed the presence of the three complexes
in the previously mentioned relative molar ratio (1:2:3′ ≈ 30:60:
10). Thus, several of these crystals were chosen, and in all cases,
X-ray diffraction studies showed that the monohydroalkylated
complex 2 cocrystallizes together with the starting product 1 to
form a solid solution (Figure 1a), which was modeled in a 60:40
molar ratio (2:1), allowing us to fully determine the structure of
complex 2 (Figure 1b). It should be noted that the presence of a
solid solution in molecular solids is not a common feature but is
a phenomenon well documented in the literature.77-85 Unfortu-
nately, we failed in choosing a crystal with the symmetrical 1,2-
dihydroalkylated compound 3′ as a component. The formation of
complexes 2 and 3′ or 4′ under thermal conditions implies only
the formal activation of one or two C-H bonds of the Cp* ligand
by interaction with the alkynyl fragments, giving rise to the final
formation of new C-H and C-C bonds and, thereby, to the novel
unsaturated bi- and tridentate ligands κP:η5-C5Me4CH2CPhd
CHPPh2 and κ2PP′:η5-C5Me3(CH2CPhdCHPPh2)2.
In an attempt to optimize the synthesis of the monohy-
droalkylated complex 2 and, probably, also to improve the
formation of the symmetrical 1,2-isomer 3′, which were thought
to be intermediates in the formation of the final asymmetrical
1,2-derivative 3, we decided to examine the reaction of the
complex [Rh(η5-Cp*)Cl(PPh2Ct CPh)2](CF3SO3) (1) with
Na2CO3 in THF at room temperature. Under these conditions,
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C-H Bond ActiVation on a Cp* Ligand
Organometallics, Vol. 28, No. 1, 2009 315
formation of the 1,2- and 1,3-symmetrical intermediate deriva-
tives 3′ and 4′ (Scheme 1, step v), which subsequently slowly
isomerize (15 h) to the corresponding asymmetrical compounds
3 and 4, presumably by sequential deprotonation and protonation
processes (1,3-hydrogen shift, Scheme 1, step vi). Interestingly,
under these conditions complex 4 is not stable, and the reaction
mixture evolves (3 days) toward complex 3 as the most abundant
product (approximate molar ratio 75:15:5:5 for 3:4:3′:4′). This
fact indicates that the asymmetrical 1,3-diactivated complex 4
isomerizes to the asymmetrical 1,2-derivative 3 (Scheme 1, step
vii), a process which implies the breaking and forming of C-C
bonds, probably because 3 is the most thermodynamically stable
compound. However, it is worth pointing out that the solid
mixtures of both 3′/4′ and 3/4 remain essentially unaltered in
solution (CDCl3 or HDA) at room temperature for long periods
of time in the absence of base, thus indicating that the
isomerization processes (3′, 4′ f 3, 4; 4 f 3) require the
presence of the base.
The initial C-H activation (formation of 2) could be
rationalized according to two different formal mechanisms
(Scheme 2). The first is a simple intramolecular transprotonation
(Scheme 2, route i), in which the migration of a proton from
the Cp* ring to the acetylenic CR atom could be followed by a
CH2-Cꢀ coupling process. This route could be favored under
thermal conditions due to the well-known polarization of the
triple bond in P-coordinated alkynylphosphines. Alternatively,
the deprotonation of a methyl group could give a η4-fulvene-
or η6-fulvene-Rh(I) intermediate (Scheme 2, route ii). The
subsequent oxidative CH2-Cꢀ coupling, followed by a final
protonation of the CR carbon, to compensate the negative charge
on this atom, would also generate the monohydroalkylated
product 2. Although this last route could seem less probable in
the absence of base, due to the wide experimental evidence
related with the electrophilic character of the exo-methylene
groups (dCH2) on fulvene ligands,6,13,71,74,86,87 nucleophilic
behavior has been also found in some η4-fulvene-rhodium
complexes.73,88 Although it has also been observed under
thermal conditions, the additional C-H activation on 2, giving
rise to 3′ and 4′, seems to be more favored in the presence of
base.
Spectroscopic and Crystallographic Characterization. In
spite of the fact that 3 is the only pure complex obtained, the
isomeric nature of all the derivatives described has been
established by elemental analyses and mass spectrometry. Thus,
the mass spectra (MALDI(+)) of 3 (Figure S1b in the Sup-
porting Information) and of different mixtures (see the Experi-
mental Section and Figures S1a and S1c in the Supporting
Information) show the peaks corresponding to m/z 845 ([M]+
23–73%) and 810 ([M - Cl]+ 100%) (M ) C50ClH45PRh). All
complexes (2, 3′, 4′, 3, and 4) have been also fully characterized
by NMR spectroscopy (including 1H{31P} and two-dimensional
1H-1H-COSY, 1H-13C HSQC, and HMBC and 1H-31P-HMBC
NMR experiments, see Figure S2 in the Supporting Information
for 3) carried out from several mixtures of the complexes. In
addition, the molecular structures of a solid mixture of 1 and 2
(Figure 1, Table 1) and of 3 (Figure 3, Table 2) have been
characterized by X-ray diffraction analyses.
Figure 1. (a) ORTEP view of the solid solution of the cations in
1 and 2 modeled in a 40:60 molar ratio, respectively. All atoms
are superimposed except C(1)-C(9). (b) ORTEP view of the cation
[Rh(κP:η5-C5Me4CH2CPhdCHPPh2)Cl(PPh2Ct CPh)]+ in complex
2. Ellipsoids are drawn at the 50% probability level. Hydrogen
atoms and solvent have been omitted for clarity.
after 5 h of reaction a mixture of the symmetrical diactivated
1,2- (3′) and 1,3-derivatives (4′) (60:40 3′:4′) can be obtained
(Scheme 1, step iii). However, after 15 h the reaction evolves
to a mixture of 3 with the new isomeric, and also asymmetrical,
1,3-dihydroactivated derivative [Rh{κ2PP′:η5-1,3-(PPh2-
CH2CPhdCH)C5Me3(CH2CPhdCHPPh2)}Cl](CF3SO3) (4) in a
ca. 1:1 molar ratio (Scheme 1, step iv). Unfortunately, all efforts
to isolate any pure compounds from both of these mixtures by
chromatography or recrystallization have been fruitless.
The monitoring by multinuclear NMR spectroscopy of the
reaction under basic conditions, either at room temperature
(Figure 2 for time-dependent 31P{1H} NMR spectra) or under
reflux conditions, has allowed us to complete the picture
(formation of 3 from 1), which is also shown in Scheme 1 (see
the Experimental Section for details). As expected, the first
product observed after 20 min was the monohydroalkylation
complex 2. This complex evolves in the presence of Na2CO3
(excess) through a second hydroalkylation reaction to the
As noted above, in spite of forming a solid solution with the
starting product 1 (Figure 1a), complex 2 has been fully
(86) Castro, A.; Turner, M. L.; Maitlis, P. M. J. Organomet. Chem. 2003,
674, 45.
(87) Fan, L.; Turner, M. L.; Adams, H.; Bailey, N. A.; Maitlis, P. M.
Organometallics 1995, 14, 676.
(88) Bellabarba, R. M.; Nieuwenhuyzen, M.; Saunders, G. C. Organo-
metallics 2002, 21, 5726.

316 Organometallics, Vol. 28, No. 1, 2009
Bernechea et al.
Figure 2. 31P{1H} NMR spectra showing the evolution of the reaction of the complex [Rh(η5-Cp*)Cl(PPh2Ct CPh)2](CF3SO3) (1) with
Na2CO3 at room temperature (asterisks indicate peaks due to OdPP2Ct CPh).
Scheme 2
Table 1. Selected Bond Distances (Å) and Angles (deg) for [Rh{KP:η5-(CH2CPhdCHPPh2)C5Me4)}Cl(PPh2Ct CPh)](CF3SO3) (2)
Rh(1)-C(Cp*)
Rh(1)-P(1)
C(22)-C(23)
C(2a)-C(4a)
2.238(7)-2.264(7)
2.3019(17)
1.168(10)
Rh(1)-C(42)
Rh(1)-P(2)
P(1)-C(1a)
C(2a)-C(3a)
2.143(7)
Rh(1)-Cl(1)
P(2)-C(22)
C(1a)-C(2a)
C(3a)-C(42)
2.4148(16)
1.750(7)
1.335(18)
1.516(14)
2.3140(18)
1.830(14)
1.527(16)
1.480(14)
P(1)-Rh(1)-Cl(1)
98.31(6)
95.22(6)
95.2(2)
110.9(3)
175.7(9)
131.9(10)
126.1(10)
P(2)-Rh(1)-Cl(1)
C(42)-Rh(1)-Cl(1)
C(42)-Rh(1)-P(2)
P(2)-C(22)-C(23)
C(1a)-P(1)-Rh(1)
C(1a)-C(2a)-C(4a)
C(42)-C(3a)-C(2a)
94.07(6)
P(1)-Rh(1)-P(2)
C(42)-Rh(1)-P(1)
C(22)-P(2)-Rh(1)
C(22)-C(23)-C(24)
P(1)-C(1a)-C(2a)
C(1a)-C(2a)-C(3a)
152.2(2)
108.7(2)
172.4(8)
109.6(4)
120.0(11)
125.7(10)
structurally characterized (Figure 1b), confirming the presence
of a functionalized η5-cyclopentadienyl ring. The angles and
distances observed in this study for molecule 1 are similar to
those found in the structure reported earlier.89 In the proposed
modelization, complex 2 shares with molecule 1 the chlorine
atom, the P(2)Ph2Ct CPh phosphine, and the η5-C5Me4 fragment

C-H Bond ActiVation on a Cp* Ligand
Organometallics, Vol. 28, No. 1, 2009 317
assignments are comparable to those reported by Nelson and
co-workers24 for the monohydroalkylated derivative [Rh{η5-
C5Me4(CH2CH2CH2PPh2)}Cl(PPh2CHdCH2)]+ (δ 31.8, -6.7),
detected only as an intermediate species, and the final 1,2- and
1,3-dihydroalkylated complexes [Rh{η5-C5Me3-1,2-(CH2CH2CH2-
PPh2)2}Cl]+ (δ 19.1) and [Rh{η5-C5Me3-1,3-(CH2CH2CH2PPh2)2}-
Cl]+(δ 22.8), which were obtained by starting from the cationic
complex [Rh(η5-Cp*)Cl(PPh2CHdCH2)2]PF6 under basic condi-
1
tions. The H NMR spectrum exhibits for complex 2 the vinylic
proton at δ 6.61 (d, 2JH-P ) 8.3 Hz), which is in good agreement
with resonances observed in similar complexes (∼7 ppm),24,90-92
and in the 3-4 ppm region the expected ABMP pattern (M, P )
31P) (δ(H) 3.71, ddd; 3.13, d) for the two diasterotopic methylenic
protons corresponding to the C5Me4CH2 group of the new κP:η5-
tetramethylcyclopentadienylvinylphosphine ligand (see Figure S3
in the Supporting Information). The high-field signal (δ 3.13)
appears as a doublet (2JH-H ) 17.6 Hz), while the proton at 3.71
ppm presents additional couplings with the two phosphorus atoms
(4JH-P ) 11.6, 4.7 Hz). The highest value is assigned to the
coupling with the PPh2Ct CPh phosphorus atom, according to the
behavior observed in the selective phosphorus-decoupling experi-
ments (Supporting Information, Figure S3c).93 The spectrum of
the mixture also shows an additional AB system centered at 3.36
ppm (JH-H ) 17.1 Hz), which remains unchanged during recording
of the 1H{31P} NMR experiments, due to the methylenic protons
of the C5Me3(CH2)2 group of the symmetrical 1,2-dihydroalkylation
derivative 3′. In the 13C{1H} NMR spectrum, the signals due to
the four methyl (δ 9.5, 9.1, 8.5, 8.2), the methylenic (δ 24.9), and
the five quaternary (δ 111.3-94.1) carbon atoms of the C5Me4CH2
group of complex 2 are clearly resolved, subtracting the corre-
sponding resonances of the precursor 1. The vinylic and acetylenic
fragments of 2 appear at 159.2 (dCPh), 119.4 (PCd), 112.3
(t CPh), and 78.8 (PCt ) ppm. The spectrum also shows signals
due to 3′, but they cannot be assigned unequivocally from this
mixture (see below for its assignment using a 60:40 mixture of 3′
and 4′).
For complex 3, a view of the structure of the cation, which
confirms the C-H bond activation of two methyl groups in the
1,2 positions of the Cp* ring, is given in Figure 3 (Table 2). A
detailed observation of the distances between the carbon atoms
of the P(2)-C(8)-C(7)-C(6) and P(1)-C(1)-C(2)-C(3)
chains indicates that the double bonds are located between the
CR and Cꢀ carbon atoms in the first chain (C(7)-C(8) )
1.351(10) vs C(6)-C(7) ) 1.551(10) Å) and between the Cꢀ
and Cγ carbon atoms (C(2)-C(3) ) 1.375(10) vs C(1)-C(2)
) 1.491(9) Å) in the second chain. The presence of the double
bonds is also corroborated by the angles around the alkenylic
(sp2) carbons, which are close to the expected value of 120°
(C(2)-C(3)-C(4) ) 127.7(7)°, C(3)-C(2)-C(1) ) 120.9(6)°,
C(15)-C(2)-C(1) ) 118.7(6)°, C(3)-C(2)-C(15) ) 120.3(6)°;
C(7)-C(8)-P(2) ) 130.5(6)°, C(8)-C(7)-C(6) ) 128.5(7)°,
C(8)-C(7)-C(33) ) 118.2(7)°, C(33)-C(7)-C(6) ) 113.2(6)°).
Figure 3. ORTEP view of the cation [Rh{κ2PP′:η5-1,2-
(PPh2CH2CPhdCH)C5Me3(CH2CPhdCHPPh2)}Cl]+ in complex 3.
Ellipsoids are drawn at the 50% probability level. Hydrogen atoms
and solvent have been omitted for clarity.
of the new chelating κP:η5 ligand. Thus, the Rh-Cl distance
(2.4148(16) Å) and the structural details of the terminal
phosphine P(2)Ph2Ct CPh (P-CR ) 1.750(7) Å; CR-Cꢀ )
1.168(10) Å; P-CR-Cꢀ ) 172.4(8)°; CR-Cꢀ-Cγ ) 175.7(9)°)
remain practically unchanged in relation to those found in the
starting product (Rh-Cl ) 2.4048(11) Å; P-CR ) 1.742(5),
1.759(5) Å; CR-Cꢀ ) 1.201(6), 1.191(6) Å; P-CR-Cꢀ
)
178.1(4), 177.9(5)°; CR-Cꢀ-Cγ ) 177.3(5), 178.1(5)°).89 With
regard to the new κP:η5-vinylphosphine ligand, the P-CR
(P(1)-C(1a)) distance increases slightly from 1.742(5) Å (in
[RhCp*Cl(PPh2Ct CPh)2]+ (1+)89) to 1.830(14) Å. Nevertheless,
boththeP-CR (P(1)-C(1a))andthevinylicCRdCꢀ (C(1a)-C(2a)
) 1.335(18) Å) distances are comparable to those found in other
κP-vinylphosphine complexes, such as [(η5-Cp*)RhCl-
(PPh2CHdCH2)2]PF6 (P-CR ) 1.803(8), 1.812(8) Å; CRdCꢀ
) 1.304(10), 1.306(10) Å).24 The angles around the CR
(P(1)-C(1a)-C(2a) ) 131.9(10)°) and Cꢀ atoms (120.0(11),
126.1(10)°) are typical of sp2 carbon atoms, although the angle
at the CR atom is slightly distorted, probably due to steric strain
of the new chelate ligand. In relation to the η5-C5Me4CH2 ring,
it should be noted that the distance Rh(1)-C(42) (2.143(7) Å)
is clearly shorter than the distances between the rhodium and
therestofthecyclopentadienylringcarbonatoms(2.238(7)-2.264(7)
Å), in agreement with the low trans influence of the chlorine
ligand, pointing to some degree of η1:η4 distortion of the ring.
Finally, unlike the case for the precursor 1, the presence of two
different types of phosphine ligands in 2 generates a chiral
center. Notwithstanding, the mixture of 1 and 2 crystallizes in
a centrosymmetric space group (P21/n) with both of the
enantiomers for 2 (R and S,R in Figure 1) present in the unit
cell.
Complex 2 has been spectroscopically characterized from the
mixture of 1, 2, and 3′ (∼30:60:10). Thus, the 31P{1H} NMR
spectra of the microcrystalline samples always show, together
with the doublet corresponding to the starting product (δ 2.3,
1JP-Rh ) 140.8 Hz, 1), the two expected resonances due to
(89) Berenguer, J. R.; Bernechea, M.; Fornie´s, J.; Go´mez, J.; Lalinde,
E. Organometallics 2002, 21, 2314.
(90) Redwine, K. D.; Hansen, H. D.; Bowley, S.; Isbell, J.; Sa´nchez,
M.; Vodak, D.; Nelson, J. H. Synth. React. Inorg. Met.-Org. Chem. 2000,
30, 379.
complex 2 (δ 30.0, dd, 1JP-Rh ) 135.5 Hz; -0.30, dd, 1JP-Rh
)
144.8; 2JP-P ) 49 Hz) and an additional small doublet (δ 23.8,
1JP-Rh ) 138.5) corresponding to the presence of the sym-
metrical 1,2-dihydroalkylated complex 3′. In 2, the high-
frequency resonance (δP 30), which is strongly deshielded in
relation to the resonance for the precursor 1, is attributed to the
vinylphosphine phosphorus atom, whereas the low-frequency
signal is assigned to the terminal alkynylphosphine. In the
context of this work, it should be pointed out that these
(91) Redwine, K. D.; Hansen, H. D.; Bowley, S.; Isbell, J.; Vodak, D.;
Nelson, J. H. Synth. React. Inorg. Met.-Org. Chem. 2000, 30, 409.
(92) Hansen, H. D.; Nelson, J. H. Organometallics 2000, 19, 4740.
(93) However, as can be observed in Figure S3b in the Supporting
Information, decoupling at the δ(P)-0.3 signal has not been completely
achieved and this has precluded the calculation of the corresponding
coupling constant. Nevertheless, the simulation and iteration of the spectrum
with the program g-NMR (version 3.6 for Macintosh, Figure S4 in the
Supporting Information) has afforded similar values for the coupling
4
constants (2JH-H ) 17.2 Hz; JH-P ) 11.7, 4.8 Hz).

318 Organometallics, Vol. 28, No. 1, 2009
Bernechea et al.
Table 2. Selected Bond Distances (Å) and Angles (deg) for [Rh{K2PP′:η5-1,2-(PPh2CH2CPhdCH)C5Me3(CH2CPhdCHPPh2)}Cl](CF3SO3) (3)
Rh(1)-C(Cp*)
Rh(1)-Cl(1)
P(1)-C(1)
2.214(6)-2.289(7)
2.3795(18)
1.853(7)
1.484(9)
1.472(11)
Rh(1)-C(4)
Rh(1)-P(1)
C(1)-C(2)
C(3)-C(4)
C(6)-C(7)
2.172(6)
2.3108(17)
1.491(9)
1.440(10)
1.551(10)
Rh(1)-C(5)
Rh(1)-P(2)
C(2)-C(3)
P(2)-C(8)
C(7)-C(8)
2.137(7)
2.2870(18)
1.375(10)
1.807(8)
C(2)-C(15)
C(5)-C(6)
1.351(10)
C(7)-C(33)
1.506(11)
P(1)-Rh(1)-Cl(1)
90.28(6)
100.73(6)
88.04(18)
152.9(2)
92.9(2)
115.8(5)
118.7(6)
127.7(7)
130.5(6)
119.1(7)
113.2(6)
P(2)-Rh(1)-Cl(1)
C(4)-Rh(1)-Cl(1)
C(4)-Rh(1)-P(2)
C(5)-Rh(1)-P(1)
C(1)-P(1)-Rh(1)
C(3)-C(2)-C(1)
C(3)-C(2)-C(15)
C(8)-P(2)-Rh(1)
C(8)-C(7)-C(6)
C(8)-C(7)-C(33)
94.80(7)
P(2)-Rh(1)-P(1)
C(4)-Rh(1)-P(1)
C(5)-Rh(1)-Cl(1)
C(5)-Rh(1)-P(2)
C(2)-C(1)-P(1)
C(15)-C(2)-C(1)
C(2)-C(3)-C(4)
C(7)-C(8)-P(2)
C(5)-C(6)-C(7)
C(33)-C(7)-C(6)
134.88(19)
129.76(19)
113.8(2)
109.7(2)
120.9(6)
120.3(6)
111.1(2)
128.5(7)
118.2(7)
1
The coordination of the η5-CH2C5Me3CHd ring is asymmetric,
with the Rh-C(4,5) distances (2.172(6), 2.137(7) Å) being
shorterthantherestoftheRh-C(Cp*)distances(2.214(6)-2.289(7)
Å), a feature which is consistent with the lower trans influence
of the chlorine atom, in relation to the phosphorus atoms. The
metal coordination is completed with the phosphorus atoms of
the vinyl (PPh2CPhdCH2) and allyl (PPh2CH2CPhdCH) phos-
phine fragments, thus generating chirality on the rhodium atom
(Figure 3 shows the enantiomer S), but as the complex
crystallizes in the centrosymmetric space group P21/c, both
enantiomeric cations, R and S, are present in the unit cell.
The difference between the chains in 3, as well as in 4, is
also evidenced in the 31P{1H} NMR spectra, which show the
expected two resonances (doublet of doublets) for each complex.
Due to their similarity with the resonances observed in complex
The H NMR spectrum of complex 3 presents four signals
associated by pairs in the 3.4-4.0 ppm region due to both CH2
groups. The inner pair of signals, which are assigned to the
two methylenic protons (CH2) of the PCH2 fragment by a
1H-31P-HMBC NMR experiment (Figure S2a in the Supporting
Information), appears as an AB system at δ 3.6 and 3.5 (JH-H
) 16.5 Hz) in the H{31P} NMR spectrum, while in the H
NMR spectrum they show additional couplings with the
phosphorus atoms, the values of which (4JH-P ≈ 5 and <10
Hz) have been calculated by selective decoupling 1H{31P}
experiments. The outer doublets (δ 3.95 and 3.34, JH-H ) 20.5
Hz) are thus attributed to the two methylenic protons (CH2) of
the η5-C5Me3CH2 fragment. In this region, complex 4 shows
three signals (3.96 (1H), 3.6 (1H) (P-CH2); 3.5 (C5Me3CH2,
2H)), whose multiplicity cannot be unambiguously assigned due
to extensive overlap with the signals of 3. Both 3 and 4 show
two different signals corresponding to the vinylic protons (δ
6.8-6.26, see the Experimental Section), which have been
1
1
1
2
2, the signals at highest field (δ 24.3, JRh-P ) 139, JP-P
)
44.5 Hz for 3; δ 23.6, 1JP-Rh ) 139, 2JP-P ) 38.5 Hz for 4) are
tentatively assigned to the corresponding phosphorus atom of
the vinyl phosphine (PCHd) arms, while the lowest field
1
assigned by H-13C-HSQC experiments. With regard to the
1
1
resonances (δ 79.0, JP-Rh ) 147 Hz for 3; δ 56.8, JP-Rh
)
corresponding symmetrical 1,2- (3′) and 1,3- (4′) diactivation
intermediates, the 1H NMR spectra show the AB system
centered at 3.36 Hz, which has also been observed in the mixture
of 1, 2, and 3′ previously described (Figure S3 in the Supporting
Information), assigned to the diasterotopic CH2 protons of 3′,
and a broad singlet at δ 3.44 corresponding to 4′, in which the
1,3-disposition would give rise to a more similar environment
for the diasterotopic methylenic protons. As expected, both of
them show only one resonance corresponding to the vinylic
protons at δ 6.75 (3′) and 6.80 (4′), which have been again
141 Hz for 4) are, therefore, ascribed to the phosphorus atoms
of the remaining arms (PCH2). In contrast, the intermediate 1,2-
(3′) and 1,3- (4′) symmetrical diactivated isomers only show
the expected doublet resonances at δ 23.8 (3′) and 25.7 (4′)
1
(see Figure 2, JP-Rh ) 138.5 Hz in both complexes). The
13C{1H} NMR spectra also agree with the proposed formula-
tions. Thus, the 1,2- (3) and 1,3- (4) asymmetrical diactivated
derivatives show three methyl, one methylenic, and five
quaternary signals due to the carbon atoms of their correspond-
ing CH2C5Me3CHd groups, as well as four resonances due to
the two different vinylic fragments. As expected, the sym-
metrical 1,2- (3′) and 1,3- (4′) dihydroalkylated intermediates
present simpler patterns, showing only two methyl, one meth-
ylenic, and three quaternary carbon signals for the C5Me3(CH2)2
unit and two signals for the equivalent vinylic fragments (see
the Experimental Section). In support of the structural proposal
suggested for the intermediate complex 3′, we note that the
quaternary cyclopentadienyl resonances of 3′ (δ 121.6, 103.7,
and 99.5) resemble those of [{η5-C5Me3-1,2-(CH2CH2-
CH2PPh2)2}RhCl]+ (δ 121.45, 103.6, and 94.1) described by
Nelson and co-workers.24This feature, together with the fact that
3′ is the only species that remains in small amounts with complex
3 in the final crude product of the reaction carried out with base
under reflux conditions (see the Experimental Section), led us to
propose this intermediate as the corresponding symmetrical 1,2-
diactivated derivative. Notwithstanding, we are aware that this
assignment is only a suitable spectroscopic proposal, since we have
not been able to isolate this complex as a pure compound or carry
out a solid-state X-ray structural study.
1
located by H-13C-HSQC experiments.
Conclusion
In summary, we have shown that easy C-H bond activations
can be promoted in the complex [(η5-Cp*)RhCl(PPh2Ct
CPh)2](CF3SO3) (1) by either thermal or basic treatment, generating
functionalized chelating mono-κP:η5- and di-κPP′:η5-cyclopenta-
dienylphosphine ligands by subsequent reaction with the triple
bonds of the PPh2Ct CPh ligands. As far as we know, this is the
first occasion in which alkynylphosphine ligands have been
involved in hydroalkylation processes. The thermal treatment
produces mainly the activation of one Cp* C-H bond to give the
new κP:η5-C5Me4CH2CPhdCHPPh2 ligand. In contrast, the pres-
ence of a weak base, such as Na2CO3, favors the double C-H
bond activation to afford initially two symmetrical 1,2- (3′) and
1,3- (4′) diactivation derivatives, which subsequently isomerize
easily by a 1,3-hydrogen shift to give the asymmetrical 1,2- (3)
and 1,3- (4) [Rh{κ2PP′:η5-(PPh2CH2CPhdCH)C5Me3(CH2CPhd
CHPPh2)}Cl]+ derivatives. In the reaction mixture complex 4 is

C-H Bond ActiVation on a Cp* Ligand
Organometallics, Vol. 28, No. 1, 2009 319
ratio, respectively). Finally, after 16 h of reaction, only complex
3 was detected, together with a small amount of compound 3′
(93:7 relative molar ratio, respectively). Then, the solvent was
removed and the solid residue (3 + 3′) extracted with CH2Cl2
to give an orange solid (0.13 g). Recrystallization from acetone/
hexane yielded compound 3 as a crystalline orange solid (0.04 g,
yield 36%). Anal. Calcd for C51ClF3H45O3P2RhS: C, 61.55; H, 4.56;
S, 3.22. Found: C, 61.37; H, 4.32; S, 3.08. MS MALDI(+): m/z
845 [M]+ 73%; 810 [M - Cl]+ 100% (M ) C50ClH45PRh). IR
(cm-1): ν(CdC) 1600 (w), 1574 (w); ν(TfO) 1273 (s), 1224 (m),
1148 (m), 1032 (m). 1H NMR (CDCl3, δ): 7.96 (m), 7.66 (m), 7.52
(m), 7.40 (m), 7.14 (m), 7.0 (m), 6.8 (m), 6.71 (m), 6.4 (m) (30 H,
Ph); 6.75 (PCHdC, 1H, overlapped with the aromatic signals); 6.58
(C5Me3CHd, 1H, overlapped with the aromatic signals); 3.95 (d,
also unstable, evolving to complex 3, which is the thermodynami-
cally most stable. Finally, it should be remarked that all the
complexes described in this paper (1, 2, 3, 4, 3′, and 4′) are isomers.
Experimental Section
All reactions were carried out under an atmosphere of dry argon,
using standard Schlenk techniques. Solvents were dried by standard
procedures and distilled under dry Ar before use. Elemental analyses
and IR, mass, and NMR spectroscopic measurements were per-
formed as described elsewhere.94 Two-dimensional NMR experi-
ments have been carried out on a Bruker ARX 400 spectrometer.
Thermal Activation of [Rh(η5-Cp*)Cl(PPh2Ct CPh)2](CF3SO3)
(1). Characterization of [Rh{KP:η5-C5Me4(CH2CPhdCHPPh2)}-
Cl(PPh2Ct CPh)](CF3SO3) (2). A suspension of 1 (0.2 g, 0.20
mmol) was refluxed in toluene for 8 h to give a mixture of 1, 2,
[Rh{κ2PP′:η5-C5Me3-1,2-(CH2CPhdCHPPh2)2}Cl](CF3SO3) (3′),
and [Rh{κ2PP′:η5-C5Me3-1,3-(CH2CPhdCHPPh2)2}Cl](CF3SO3)
(4′) in the approximate molar ratio 25:57:12:6, respectively (31P{1H}
NMR). Evaporation of the solvent and treatment of the residue with
diethyl ether afforded a mixture of complexes 1, 2, and 3′ (∼30:
60:10, respectively) as a yellow solid (0.13 g), which could not be
separated by chromatography or repeated crystallizations in different
solvents. The spectroscopic data of 2 have been obtained from this
mixture (Anal. Found: C, 61.64; H, 4.49; S, 3.25. Calcd for
C51ClF3H45O3P2RhS: C, 61.55; H, 4.56; S, 3.22). Mass spectrum
(MALDI(+)) of the reaction mixture of 1, 2, 3′, and 4′: m/z 845
([M]+ 23%), 810 ([M - Cl]+ 100%) (M ) C50ClH45PRh).
This reaction has been optimized to obtain the maximum relative
amount of complex 2. Longer reaction times lead to mixtures having
higher proportions of complexes 3′ and 4′.
JH-H ) 20.5, 1H, C5Me3CH2); 3.6, 3.5 (ABXY system, JH-H
)
16.5, 2H, PCH2); 3.34 (d, JH-H ) 20.5, 1H, C5Me3CH2); 1.96 (d,
4
4JH-P ) 8.1, 3H, CH3, C5Me3); 1.89 (d, JH-P ) 4.5, 3H, CH3,
C5Me3); 1.28 (“t”, 4JH-P ) 6.5, 3H, CH3, C5Me3). 13C NMR (CDCl3,
2
2
δ): 161.5 (d, JP-C ) 14.7, PCHdCPh); 144.8 (d, JP-C ) 3.3,
3
PCH2CPhd); 142.1 (d, JP-C ) 15.9, ipso-C, PCHdCPh); 141.1
(d, 3JP-C ) 4.7, ipso-C, PCH2CPhd); 135-125 (m, Ph); 127.9 (dm,
1JRh-C ≈ 10, CCHd, C5Me3); 123.5 (dd, JRh-C ) 6.5, JP-C
)
1
2
3
3.4, C5Me3); 122.5, 119.3 (s, Ph); 115.7 (d, JP-C )5.5,
1
1
C5Me3CHd); 114.8 (d, JP-C ) 52.6, PCHd); 109.5 (ddd, JRh-C
2
) 9.6, JP-C ) 3.2, 1.7, C5Me3); 101.9 (d, JP-H ) 5.8, Ph); 101.8
1
2
(dd, JRh-C ) 14.5, JP-C ) 3.7, C5Me3); 83.2 (doublet of
pseudotriplets, 1JRh-C ) 7.3, 2JP-C ≈ 2.5, CCH2, C5Me3); 35.9 (d,
1JP-C ) 23.3, PCH2); 26.3 (d, JP-C ) 3.0, C5Me3CH2); 10.4 (d,
3
3JP-C ) 2.1, C5Me3); 10.0 (d, 3JP-C ) 2.4, C5Me3); 9.9 (d, 3JP-C
)
3.7, C5Me3). 19F NMR (CDCl3, δ): -78.35 (s, 3F, CF3). 31P NMR
(CDCl3, δ): 79.0 (dd, 1JP-Rh ) 147, PCH2); 24.3 (dd, 1JP-Rh ) 139,
PCHd) (2JP-P ) 44.5).
Data for 2 are as follows. IR (cm-1): ν(Ct C) 2172 (m); ν(CdC)
1590 (w); ν(TfO) 1272 (s), 1224 (m), 1150 (m), 1031 (m). 1H NMR
(CDCl3, δ): 8.2-6.7 (m, Ph); 6.61 (d, 2JH-P ) 8.3, 1H, PCHdC);
Activation of 1 at Room Temperature. Synthesis of Mixtures
of 3 and 4 (50:50) and 3′ and 4′ (60:40). A solution of 1 (0.15 g,
0.15 mmol) in THF was treated with Na2CO3 (0.16 g, 1.5 mmol),
and the mixture was stirred at room temperature, while the reaction
was monitored by 31P{1H} NMR spectroscopy (see Figure 2). After
15 h, the most abundant species were compounds 3 and 4 (∼ 50:
50). Then, the solvent was removed and the crude mixture extracted
with CH2Cl2 and filtered. The filtrate was evaporated to dryness
and treated with Et2O,yielding a mixture of complexes 3 and 4
(∼50:50 molar ratio) as an orange solid (0.135 g, yield 90%). By
a similar treatment, but with the reaction being stopped after 5 h,
we obtained a mixture of complexes 3′ and 4′ (∼ 60:40) as an
orange solid (0.12 g, yield 83%). All attempts to isolate any of
these complexes by chromatography or recrystallization from these
mixtures have been also fruitless. Mass spectra (MALDI(+)) of
these mixtures show peaks corresponding to m/z 845 ([M]+ 37%)
and 810 ([M - Cl]+ 100%) (M ) C50ClH45PRh).
3.71 (ABMP system, JH-H ) 17.6, 4JH-P ) 11.6, 4JH-P ) 4.7, 1H,
4
CH2); 3.13 (AB system, JH-H ) 17.6, 1H, CH2); 1.59 (d, JH-P
)
4
5.4, 3H, CH3, C5Me4); 1.56 (d, JH-P ) 6.7, 3H, CH3, C5Me4);
1.42 (d, 4JH-P ≈ 5, CH3, C5Me4; the signal overlaps with the triplet
corresponding to the CH3 (Cp*) of 1); 1.34 (s broad, CH3, C5Me4).
13C NMR (CDCl3, δ): 159.2 (d, JP-C ) 14.0, PCHdCPh); 140.6
2
(d, 3JP-C ) 15.6, ipso-C, PCHdCPh); 135-125 (m, Ph); 122.4 (s,
1
Ph); 119.4 (d, JP-C ) 52.3, PCHd); 119.5 (d, JP-H ) 3.0, Ph);
119.2 (s, Ph); 112.3 (d, 2JP-C )11.9, Cꢀ); 111.3 (dd, 1JRh-C ) 5.2,
2JP-C ≈ 3, C5Me4); 108.6 (dd, JRh-C ) 16.3, JP-C ) 2.8, CCH2,
1
2
1
2
C5Me4); 108.3 (d, JRh-C ) 15.7, C5Me4); 106.9 (d, JP-C ) 3.1,
C5Me4); 94.1 (d, 1JRh-C ) 6.4, C5Me4); 78.8 (d, 1JP-C )104.1, CR);
24.9 (d, 3JP-C ) 5.5, C5Me4CH2); 9.5 (d, 3JP-C ) 2.5, C5Me4); 9.1
(d, 3JP-C ) 2.7, C5Me4); 8.5 (d, 3JP-C ) 2.1, C5Me4); 8.2 (s, C5Me4).
19F NMR (CDCl3, δ): -78.42 (s, 3F, CF3). 31P{1H} NMR (CDCl3,
δ): 30.0 (dd, JP-Rh ) 135.5, η5-P); -0.3 (dd, JP-Rh ) 144.8,
1
1
PPh2Ct CPh) (2JP-P ) 53.0).
When the initial mixture is allowed to react for 3 days, complex
3 was the most abundant species (approximate molar ratio 3:4:3′:
4′ 75:15:5:5).
Thermal Activation of 1 in the Presence of Base. Synthesis of
[Rh{K2PP′:η5-1,2-(PPh2CH2CPhdCH)C5Me3(CH2CPhdCHPPh2)}
Cl](CF3SO3) (3). A 0.12 g (1.14 mmol) portion of Na2CO3 was
added to a solution of compound 1 (0.15 g, 0.15 mmol) in THF,
and the mixture was heated to reflux. A study of the reaction
(31P{1H} NMR) shows the presence of complexes 2, 3′, and 4′,
together with starting product 1 (41:22:12:25 relative molar ratio,
respectively), after 20 min of reaction. With the passing of the
reaction time, the relative amount of complexes 3′ and 4′
increased and, after 6 h, complexes 3 and [Rh{κ2PP′:η5-1,3-
(PPh2CH2CPhdCH)C5Me3(CH2CPhdCHPPh2)}Cl](CF3SO3) (4)
were already observed (3:4:3′:4′ relative molar ratio 19:3:51:
27). After 10 h, the main product detected was complex 3 with
a small amount of intermediates 3′ and 4′ (78:18:4 relative molar
Data for 4 (Obtained from the Mixture of 3 and 4 (50:50)). Anal.
Calcd for C51ClF3H45O3P2RhS: C, 61.55; H, 4.56; S, 3.22. Found:
1
C, 61.63; H, 4.45; S, 3.11. H NMR (CDCl3, δ): 7.96 (m), 7.65
(m), 7.53 (m), 7.41 (m), 7.15 (m), 7.02 (m), 6.82 (m), 6.71 (m),
6.3 (br s) (Ph corresponding to 3 and 4); 6.8 (PCHdC, 1H,
overlapped with the aromatic signal); 6.26 (m, C5Me3CHd, 1H);
3.96 (1H), 3.6 (1H) (PCH2); 3.5 (C5Me3CH2, 2H) (the multiplicity
of both of the methylenic signals has not been clearly elucidated
owing to extensive overlap with the signals corresponding to
complex 3); 1.81 (d, 4JH-P ) 6.6, 3H, CH3, C5Me3); 1.76 (d, 4JH-P
) 7.4, 3H, CH3, C5Me3); 1.30 (m, 3H, CH3, C5Me3; this signal
overlaps with one corresponding to complex 3). 13C NMR (CDCl3,
2
2
δ): 160.0 (d, JP-C ) 13.5, PCHdCPh); 142.0 (d, JP-C ≈ 5,
PCH2CPhd); 141.3 (d, 3JP-C ≈ 5, ipso-C, PCH2CPhd); 140.7 (d,
3JP-C ) 15.1, ipso-C, PCHdCPh); 135-125 (m, Ph); 118.8 (d,
(94) Berenguer, J. R.; Lalinde, E.; Torroba, J. Inorg. Chem. 2007, 46,
9919.

320 Organometallics, Vol. 28, No. 1, 2009
Bernechea et al.
Table 3. Crystallographic Data for 2 and 3
2
3
empirical formula
formula wt
temp (K)
cryst syst
space group
a (Å)
C51H45ClF3O3P2RhS
995.23
123(1)
monoclinic
P21/n
15.4650(3)
15.0860(3)
19.0140(4)
C51H45ClF3O3P2RhS
995.23
100(1)
monoclinic
P21/c
16.0340(6)
15.2010(6)
19.6740(4)
90
113.367(2)
90
4401.9(3)
4
1.502
0.626
b (Å)
c (Å)
R (deg)
90
ꢀ (deg)
90.5170(10)
90
4435.88(15)
4
1.490
0.621
2040
γ (deg)
V (Å3)
Z
Dcalcd (Mg/m3)
abs coeff (mm-1
F(000)
)
2040
cryst size (mm)
0.4 × 0.4 × 0.2
0.15 × 0.15 × 0.10
3.63-25.35
8048/28/589
1.076
θ range for data collecn (deg)
no. of data/restraints/params
goodness of fit on F2
3.41-26.37
9033/25/556
1.039
final R indices (I > 2σ(I))
R1 ) 0.0861, wR2 ) 0.2357
R1 ) 0.1131, wR2 ) 0.2644
1.565, -2.070
R1 ) 0.0786, wR2 ) 0.1750
R1 ) 0.0988, wR2 ) 0.1861
2.467, -1.109
R indices (all data)
largest diff peak, hole (e Å-3
)
1JP-C ) 51.6, PCHd); 116.6 (dd, 1JRh-C ) 4.9, 2JP-C ) 2.9, C5Me3);
were assigned anisotropic displacement parameters. For the solid
solution of complexes 1 and 2, we present the best of the analyses
performed on three different crystals chosen from the same crude
mixture. In the three cases the analyses were modeled in a 40:60
molar ratio (1:2). Both isomers share most of the structure, except
the carbon atoms C1-C9 (a for the vinylphosphine ligand in 2
and b for the alkynylphosphine in 1). No restraints on bond
distances or angles were made in refining the positions of C1a/b,
C2a/b, and C3a/b. For complex 3, two phenyl rings (C27-C32
and C39-C44) present positional disorder, which could be refined
over two positions with partial occupancy factors of 0.5/0.5 and
0.6/0.4, respectively. In both structural determinations the triflate
cation was also disordered and modeled adequately. Complexes 2
and 3 have a chiral center at the Rh atom with both of the
enantiomers, R and S, present in the unit cell (Figure 1 shows the
enantiomer R and Figure 3 the enantiomer S). Finally, in both
structural determinations some residual peaks greater than 1 e Å-3
were observed in the vicinity of the heavy atoms or the disordered
triflates, but these had no chemical significance.
3
1
115.2 (d, JP-C ) 5.0, C5Me3CHd); 109.7 (dbr, JRh-C ≈ 10,
C5Me3); 108.6 (d, 1JRh-C ) 10.5, C5Me3); 102.2 (pseudotriplet, 2JP-C
≈ 4, CCHd, C5Me3); 98.2 (d, 1JRh-C ≈ 7.7, C5Me3); 31.4 (d, 1JP-C
3
) 26.7, PCH2); 29.7 (s, C5Me3); 25.3 (d, JP-C ≈ 5, C5Me3CH2);
9.8 (d, 3JP-C ) 3.2, C5Me3); 9.2 (d, 3JP-C ) 3.4, C5Me3). 19F NMR
(CDCl3, δ): -78.35 (s, 3F, CF3). 31P NMR (CDCl3, δ): 56.8 (dd,
1
1JP-Rh ) 141); 23.6 (dd, JP-Rh ) 139) (2JP-P ) 38.5).
Data for 3′. Anal. Calcd for C51ClF3H45O3P2RhS: C, 61.55; H,
4.56; S, 3.22. Found (from a mixture of 3′ and 4′ 60:40): C, 61.41;
H, 4.39; S, 3.29. 1H NMR (CDCl3, δ): 8-6.4 (m, Ph); 6.75
(PCHdC, 2H, overlapped with the aromatic signal); 3.36 (AB
system, δA 3.30, δB 3.42, JH-H ) 17.1, 4H, C5Me3CH2); 1.77 (d,
4
4JH-P ) 2.8, 3H, CH3, C5Me3); 1.22 (“t”, JH-P ≈ 5, 6H, CH3,
2
C5Me3). 13C NMR (CDCl3, δ): 159.5 (d, JP-C ) 8, PCHdCPh);
140.5 (d, 3JP-C ≈ 9, ipso-C, PCHdCPh); 135-125 (m, Ph); 121.6
2
1
(d, JP-C ) 3.1, C5Me3); 116.4 (d, JP-C ) 57.1, PCHd); 103.7
(dd, 1JRh-C ) 12, 2JP-C ) 5, C5Me3); 99.5 (d, 1JRh-C ) 7.7, C5Me3);
24.6 (sbr, C5Me3CH2); 9.3 (sbr, 1CH3, C5Me3); 8.8 (sbr, 2CH3,
C5Me3). 31P NMR (CDCl3, δ): 23.8 (d, JP-Rh ) 138.5).
1
Data for 4′. 1H NMR (CDCl3, δ): 8-6.4 (m, Ph); 6.80 (PCHdC,
2H, overlapped with the aromatic signal); 3.44 (sbr, 4H,
C5Me3CH2); 1.61 (“t”, 4JH-P ≈ 3, 6H, CH3, C5Me3); 0.88 (sbr, 3H,
Acknowledgment. We wish to thank the Ministerio de
Ciencia y Tecnolog´ıa of Spain and the European Regional
Development Fund (Project CTQ2005-08606-C02-02/BQU)
for financial support. M.B. and J.T. thank the CAR for a
grant. We thank Professor J. Fornie´s for helpful discussions
and encouragement.
CH3, C5Me3). 13C NMR (CDCl3, δ) 159.6 (d, JP-C ) 8,
2
3
PCHdCPh); 140.6 (d, JP-C ≈ 9, ipso-C, PCHdCPh); 135-125
(m, Ph); 117.2 (d, 1JP-C ) 52.0, PCHd); 109.9 (dd, 1JRh-C ) 5.6,
2JP-C ≈ 3, C5Me3); 107.1 (dm, 1JRh-C ≈ 5, C5Me3); 92.4 (d, 1JRh-C
) 7.4, C5Me3); 25.0 (sbr, C5Me3CH2); 9.4 (sbr, 1CH3, C5Me3); 9.0
(sbr, 2CH3, C5Me3). 31P NMR (CDCl3, δ): 25.7 (d, 1JP-Rh ) 138.5).
X-ray Crystallography. Table 3 reports details of the structural
analyses for all of the complexes studied. Orange crystals of
complex 3 and of a solid solution of complexes 1 and 2 were
obtained by slow diffusion of n-hexane into acetone solutions of
complex 3 or a mixture of complexes 1, 2, and 3′ (30:60:10,
respectively) at room temperature. X-ray intensity data were
collected with a NONIUS κCCD area-detector diffractometer, using
graphite-monochromated Mo KR radiation. Images were processed
using the DENZO and SCALEPACK suite of programs.95 The
structures were solved by Patterson and Fourier methods using the
DIRDIF92 program,96 and the absorption correction was performed
using SORTAV.97 All structures were refined by full-matrix least
squares on F2 with SHELXL-97,98 and all non-hydrogen atoms
Supporting Information Available: Figures giving mass spectra
(MALDI(+)) of a mixture of complexes 1, 2, 3′, and 4′, of pure
1
complex 3, and a mixture of complexes 3 and 4, H-31P-HMBC
1
1
and H-13C HSQC and HMBC NMR spectra of 3, H, selective
1H{31P}, and H{31P} NMR spectra of the mixture of complexes
1, 2, and 3′, and simulation of the H NMR spectra of complex 2
1
1
and CIF files giving further crystallographic data of the structure
determinations of 3 and the solid mixture of 1 and 2. This material
is available free of charge via the Internet at http://pubs.acs.org.
OM800867H
(96) Beurskens, P. T.; Beurskens, G.; Bosman, W. P.; de Gelder, R.;
Garc´ıa-Granda, S.; Gould, R. O.; Smith, J. M. M.; Smykalla, C. The
DIRDIF92 Program System, Technical Report of the Crystallography
Laboratory; University of Nijmegen, Nijmegen, The Netherlands, 1992.
(97) Blessing, R. H. Acta Crystallogr. 1995, A51, 33.
(98) Sheldrick, G. M. SHELX-97, Program for the Refinement of Crystal
Structures; University of Go¨ttingen, Go¨ttingen, Germany, 1997.
(95) Otwinowski, Z.; Minor, W. In Methods in Enzymology; Carter,
C. V., Jr., Sweet, R. M., Eds.;Academic Press: New York, 1997; Vol. 276A,
p 307.