Carbenerhodium(I) complexes of the half-sandwich-type: Reactions with electrophiles

Article abstract of DOI:10.1039/b008354m

The reaction of the carbenerhodium(I) complexes [(η⁵-C₅H₅)Rh(=CR₂)(L)] (R = aryl) with HX (X = Cl, CF₃CO₂) led, depending on the size and donor properties of the ligand L, to two different types of products. While compounds 1, 2 with R = Ph and L = CO or PMe₃ react with HX to give rhodium(III) alkyls [(η⁵-C₅H₅)RhX(CHPh₂)(L)] 3, 4a,b, the analogues 5a and 5b with R = Ph, p-Tol and L = PPrⁱ₃ afford upon treatment with HX (X = Cl, Br, I, CF₃CO₂) the ring-substituted products [{η⁵-C₅H₄(CHR₂)}RhHX(PPrⁱ ₃)] 6a-e. In the presence of excess HX, the latter are converted into the dihalo or bis(trifluoroacetato) derivatives [{η⁵-C₅H₄(CHR₂)}RhX₂( PPrⁱ₃)] 7a-e. A labelling experiment using [(η⁵-C₅D₅)Rh(=CPh₂)(PPrⁱ ₃] 5a-d₅ as a precursor indicates that the migratory insertion of the carbene into a C-H bond of the cyclopentadienyl ring probably occurs via an η⁴-cyclopentadienerhodium(I) species as an intermediate. The triphenylphosphine complex [{η⁵-C₅H₄(CHPh₂)} RhCl₂(PPh₃)] 7f was prepared analogously from 5c and two equiv. of HCl. The reactions of 5a and 5d (R = Ph, L = SbPrⁱ₃) with either HBF₄, [Me₃O]BF₄ or methyl triflate give via attack of the electrophile on the carbene carbon atom and subsequent σ/π rearrangement cationic η³-benzylrhodium(III) complexes 9 and 10a-c in good to excellent yields. Treatment of 5a and 5d with iodine results in the cleavage of the metal-carbene bond and affords the diiodo compounds [(η⁵-C₅H₅)RhI₂(L)] 12a,b.

Full text of DOI:10.1039/b008354m

View Article Online / Journal Homepage / Table of Contents for this issue
Carbenerhodium(I) complexes of the half-sandwich-type:
reactions with electrophiles
Elke Bleuel, Peter Schwab, Matthias Laubender and Helmut Werner*
Institut für Anorganische Chemie der Universität Würzburg, Am Hubland, D-97074 Würzburg,
Germany. E-mail: helmut.werner@mail.uni-wuerzburg.de
Received 17th October 2000, Accepted 5th December 2000
First published as an Advance Article on the web 16th January 2001
The reaction of the carbenerhodium() complexes [(η5-C H )Rh(᎐CR )(L)] (R = aryl) with HX (X = Cl, CF CO )
᎐
5
5
2
3
2
led, depending on the size and donor properties of the ligand L, to two different types of products. While compounds
1, 2 with R = Ph and L = CO or PMe3 react with HX to give rhodium() alkyls [(η5-C5H5)RhX(CHPh2)(L)] 3, 4a,b,
the analogues 5a and 5b with R = Ph, p-Tol and L = PPri3 afford upon treatment with HX (X = Cl, Br, I, CF3CO2)
the ring-substituted products [{η5-C5H4(CHR2)}RhHX(PPri3)] 6a–e. In the presence of excess HX, the latter are
converted into the dihalo or bis(trifluoroacetato) derivatives [{η5-C5H4(CHR2)}RhX2(PPri3)] 7a–e. A labelling
experiment using [(η5-C D )Rh(᎐CPh )(PPri )] 5a-d as a precursor indicates that the migratory insertion of the
᎐
5
5
2
3
5
carbene into a C–H bond of the cyclopentadienyl ring probably occurs via an η4-cyclopentadienerhodium() species
as an intermediate. The triphenylphosphine complex [{η5-C5H4(CHPh2)}RhCl2(PPh3)] 7f was prepared analogously
from 5c and two equiv. of HCl. The reactions of 5a and 5d (R = Ph, L = SbPri3) with either HBF4, [Me3O]BF4 or
methyl triflate give via attack of the electrophile on the carbene carbon atom and subsequent σ/π rearrangement
cationic η3-benzylrhodium() complexes 9 and 10a–c in good to excellent yields. Treatment of 5a and 5d with iodine
results in the cleavage of the metal–carbene bond and affords the diiodo compounds [(η5-C5H5)RhI2(L)] 12a,b.
In the context of our investigations on the reactivity of square-
the five-coordinate alkylrhodium() compound [RhCl2-
(CHPh2)(PPri3)2],1 the cyclopentadienyl derivatives [(η5-C5H5)-
planar carbenerhodium() complexes trans-[RhCl(᎐CRRЈ)(L) ],
᎐
2
where L is a tertiary phosphine, arsine or stibine,1 we recently
found that the chloro ligand of these compounds can easily be
displaced not only by other halides but also by C-, N- or
O-nucleophiles.2 Among the products obtained by the substitu-
tion reactions, the cyclopentadienyl derivatives [(η5-C5H5)-
Rh(᎐CPh )(L)] with L = CO (1) and PMe (2) also react with
᎐
2
3
Brønsted acids by oxidative addition to give the complexes 3
and 4a,b in good to excellent yields (Scheme 1). The phosphine
Rh(᎐CRRЈ)(L)] deserve particular attention insofar as they
᎐
belong to the type of half-sandwich compounds which in gen-
eral behave as metal bases.3 Extensive work from our laboratory
in the period of 1975–1985 has shown that complexes such as
[(η5-C5H5)M(PR3)2], [(η5-C5H5)M(CO)(PR3)] or [(η5-C5H5)-
M(C2H4)(PR3)] with M = Co, Rh, or Ir react, in some cases
under extremely mild conditions, with electrophiles EX by
oxidative addition to form products with a new M–E bond.4
Since the related carbene compounds [(η5-C H )Rh(᎐CRRЈ)-
᎐
5
5
(L)], like the vinylidene counterparts,5 contain a highly reactive
Rh–C double bond the question arose whether electrophiles
such as HX or RX would preferentially attack the metal centre
or the more electronegative carbene carbon atom.
The results reported in this paper show that, independent of
the direction of the attack of the electrophile, the compounds
formed in the initial step of the reaction of the half-sandwich-
type carbenerhodium() complexes with HX or RX are mostly
quite labile and rearrange either by migratory insertion or by
generating an η3-benzyl system. The interesting aspect is that
more than the donor/acceptor capabilities the size of the ligand
L plays a dominating role in determining the structure of the
final product. Some preliminary observations of these studies
have already been communicated.6
Scheme 1
compound 2 is considerably more reactive than the carbonyl
analogue which probably reflects the greater metal basicity of
2 compared with 1. The rhodium() alkyls 3 and 4a,b are red
to orange-red solids which can be stored under argon for days
but more or less rapidly decompose in benzene solution. Not
unexpectedly, the carbonyl compound 3 is more labile than the
phosphine counterparts 4a,b. The most typical spectroscopic
1
features are the H NMR resonance of the CHPh2 proton at
around δ 4.8–5.6 (which appears as a doublet for 3 and as a
doublet of doublets for 4a and 4b) and the 13C NMR signal of
the corresponding alkyl carbon atom CHPh2 at δ 42.4 (4a) and
47.0 (4b), respectively. The assignment of the latter has been
confirmed by DEPT measurements. It should be mentioned
that the formation of 4a was observed for the first time when
we attempted to purify the starting material 2 by column
chromatography using acidic Al2O3 as the support. This result
can be understood by taking into consideration that all the
Results and discussion
Addition of HX to the Rh᎐C double bond
᎐
Like the four-coordinate carbenerhodium() complex trans-
[RhCl(᎐CPh )(PPri ) ], which upon treatment with HCl affords
᎐
2
3 2
266
J. Chem. Soc., Dalton Trans., 2001, 266–273
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b008354m

View Article Online
commercial samples of acidic alumina contain traces of
chloride ions thus making the conversion of 2 to 4a possible.
With regard to the mechanism of the reaction of 1 and 2 with
HX to yield 3 and 4a,b, two routes are conceivable. First, the
electrophile could attack the CPh2 carbon atom which in the
simplified terminology is part of a Schrock-type carbene
ligand. Second, the attack of the electrophile could be directed
at the electron-rich metal centre generating a cationic species
In order to elucidate the mechanism of formation of the
ring-substituted complexes 6a–e, a labelling experiment was
carried out. Treatment of 5a-d5, which was prepared from
trans-[RhCl(᎐CPh )(PPri ) ] and TlC D in THF, with an equi-
᎐
2
3
2
5
5
molar amount of HCl in benzene affords exclusively the com-
pound 6a-d5 (Scheme 3). Regarding the individual steps of this
[(η5-C H )RhH(᎐CPh )(L)]ϩ as an intermediate which, assisted
᎐
5
5
2
by the anion XϪ, rearranges to give the final product. We feel
that the course of the reactions of [(η5-C5H5)Rh(CO)(PMe3)]7
and [(η5-C5H5)Rh(C2H4)(PMe3)]8 with HX to afford the
cations [(η5-C5H5)RhH(L)(PMe3)]ϩ (L = CO, C2H4) supports
the second possibility.
HX-induced migratory insertion reactions
In contrast to 1 and 2, the structurally related carbene com-
plexes 5a and 5b containing the more bulky phosphine PPri3 as
ancillary ligand react with an equimolar amount of HX
(X = Cl, Br, I, CF3CO2) to form the ring-substituted products
6a–e in 84–93% isolated yield (Scheme 2). For the preparation
Scheme 3
reaction, we assume that initially the addition of the Brønsted
acid to the carbene–rhodium bond takes place, similar to the
formation of 4a from 2 and HCl (see Scheme 1). The intermedi-
ate A then reacts by migration of the CHPh2 unit to the C5D5
ligand to generate the substituted cyclopentadienerhodium()
species B. A subsequent 1,2-D-shift along the five-membered
ring affords the intermediate C which, by deuterium transfer
from the sp3-carbon atom of the C5 moiety to the metal,
gives the final product 6a-d5. Reaction of 6a-d5 with HCl
results in the formation of 7a-d4 which has been characterized
spectroscopically. An isotopomer of C of the composition
[RhCl(η4-C5H5CHPh2)(PPri3)] is probably also involved in the
reaction of the dimer [RhCl(PPri3)2]2 8 with C5H5CHPh2 to
yield 6a (Scheme 4). This alternative method to prepare 6a is
Scheme 2
of 6a, 6b and 6e, instead of HCl or HBr also Me3SiCl or
Me3SiBr can be used as the substrate which in the presence of
traces of water generate in situ the corresponding Brønsted acid
1
HX. In agreement with the proposed structure, the H NMR
spectra of 6a–e display a hydride resonance at δ Ϫ11 to Ϫ13,
which due to Rh–H and P–H couplings is split into a doublet of
doublets. The C5H4 ring protons give rise to four separated
signals between δ 5.4–4.2, thus confirming the non-equivalence
of these protons in the chiral compounds.
Scheme 4
reminiscent of earlier work from this laboratory which showed
that treatment of 8 with cyclopentadiene results in the form-
ation of the rhodium() complex [(η5-C5H5)RhHCl(PPri3)]
in excellent yield.11 With regard to intermediate B we note
that recently Hughes et al. reported the isolation of coordin-
atively saturated (η4-C5H5R)Rh compounds (R = CF2CF2CF3,
CF(CF3)2) which were formed from [(η5-C5H5)Rh(PMe3)2] and
perfluoroalkyl iodides.12
The reactions of 5a and 5b with an excess instead of an
equimolar amount of HX afford almost quantitatively the
dihalo or bis(trifluoroacetato) derivatives 7a–e. They are equal-
ly generated upon treatment of 6a–e with HX. In contrast to
6a–e, the substituted compounds 7a–e are significantly more
stable and for a short period of time can even be handled in air.
The 31P NMR spectra of 7a–e display the expected doublet at
δ 57–62 which is about 18–25 ppm upfield compared with 6a–e.
A similar upfield shift is observed for the 31P resonance of the
triphenylphosphine complex 7f, prepared from 5c and excess
hydrogen chloride. In contrast to the labile chloro(hydrido)
intermediate [{η5-C5H4(CHPh2)}RhHCl(PPh3)], 7f has been
characterized not only by spectroscopic data but also by
elemental analysis.
The reaction of the PPh3-containing carbene complex 5c
with HCl probably takes a similar course to that of 5a. Drop-
wise addition of Me3SiCl to a solution of 5c in acetone which
has not been rigorously dried leads to an instant change of
color from blue-violet to orange and gives, after removal of the
solvent, an extremely air-sensitive residue which, from the
spectroscopic data, mainly consists of the chloro(hydrido)-
rhodium() compound [{η5-C5H4(CHPh2)}RhHCl(PPh3)].
Characteristic features for this molecule are the doublet of
doublets for the Rh–H proton at δ Ϫ10.47 (with J(Rh,H) 41.5
1
and J(P,H) 12.5 Hz) in the H NMR and the doublet at δ 46.7
in the 31P NMR spectrum; the 31P–103Rh coupling constant of
150.8 Hz of this signal seems to be typical for a piano-stool-
type phosphinerhodium() species.9 Attempts to isolate the
complex [{η5-C5H4(CHPh2)}RhHCl(PPh3)] in analytically
pure form failed. We note, however, that in the context of
our studies on the chemistry of (η5-C5H4SiMe3)Rh deriv-
atives we recently prepared the related chloro(hydrido) com-
pound [{η5-C5H3(CHPh2)SiMe3}RhHCl(PPh3)],10 which is
considerably more stable than the {η5-C5H4(CHPh2)}Rh
counterpart.
J. Chem. Soc., Dalton Trans., 2001, 266–273
267

View Article Online
Table 1 Selected bond lengths (Å) and angles (Њ) for complex 7a
Rh–P
2.328(1)
2.382(1)
2.400(1)
2.155(4)
Rh–C(2)
Rh–C(3)
Rh–C(4)
Rh–C(5)
2.167(4)
2.135(4)
2.237(4)
2.226(4)
Rh–Cl(1)
Rh–Cl(2)
Rh–C(1)
P–Rh–Cl(1)
P–Rh–Cl(2)
C(l)1–Rh–Cl(2)
89.79(4)
95.72(4)
94.30(4)
C(5)–C(6)–C(20)
C(5)–C(6)–C(30)
C(20)–C(6)–C(30)
111.1(4)
110.2(4)
115.9(4)
in rapid formation of a dark red precipitate 9 the elemental
analysis of which corresponds to that of a 1:1 adduct of the
starting material and HBF4. Compound 9 is thermally quite
stable (it decomposes at 100 ЊC), only slightly air-sensitive and
easily soluble in CH2Cl2 and nitromethane. In solutions of
acetone slow decomposition occurs. The proposed structure,
Fig. 1 ORTEP13 plot of 7a.
1
which is shown in Scheme 5, is supported both by the H and
the 13C NMR spectra. The appearance of three resonances for
the 13C nuclei of the carbon atoms C1, C2 and C7 (for assign-
ment see the Experimental section) at δ 96.1, 87.3 and 64.5 is
consistent with an η3-benzylic type of coordination of the
C6H5CHC6H5 unit, quite similarly as in the trimethylphosphine
complex [(η5-C5H5)Rh(η3-C6H5CHCH3)(PMe3)]BF4.8 Since the
two CH protons situated ortho to the CHPh fragment at
the partially bonded C6H5 ring give rise to two separated signals
The proposed structure for the dihalorhodium() com-
pounds [{η5-C5H4(CHPh2)}RhX2(PPri3)] was confirmed by a
single-crystal X-ray diffraction study of 7a. The ORTEP13 plot
(Fig. 1) illustrates the three-legged piano-stool configuration
of the molecule. A characteristic feature is that the CHPh2
substituent is pointing away from the triisopropylphosphine
therefore minimizing the steric repulsion between the two bulky
moieties. While the Rh–C(ring) distances of 7a are somewhat
shorter than in the related rhodium() complex [{η5-C5H4-
(CHPh2)}Rh(PF3)(PPri3)],6 being in agreement with the higher
oxidation state of the metal in 7a, the Rh–PPri3 bond length in
7a is slightly longer than in the PF3 derivative. The P–Rh–Cl
and Cl–Rh–Cl angles in 7a (see Table 1) are near to 90Њ, which
reflects the pseudo-octahedral geometry of the molecule.
1
in the H NMR spectrum at δ ca. 7.6 and 3.5, we assume that
the η3-benzylic ligand is rigid (i.e., does not rotate) on the NMR
timescale. The comparison of the spectroscopic data of 9 with
those of the related ruthenium complex [(η5-C5H5)Ru(η3-C6-
H5CHC6H5)(PPh3)]14 suggests that the exo isomer with the
plane of the η3-benzylic unit pointing away from the metal
centre is preferred. The chemical shift of the resonance of the
C6H5CHC6H5 proton at δ 2.09 supports this proposal.
Formation of ꢀ3-benzylrhodium complexes from Rh᎐CRRЈ
᎐
The reactions of 5a and 5d with Meerwein’s reagent
[Me3O]BF4 take a similar course. Addition of the oxonium salt
to a solution of the respective carbene complex in ether/
methanol (1:1) leads to a smooth change of color from dark
blue to red and, after removal of the solvent and recrystallis-
ation of the residue from CH2Cl2/ether, to the isolation of red,
precursors
The diarylcarbenerhodium() complexes 5a (L = PPri3) and 5d
(L = SbPri3) are also highly reactive toward acids or methylating
reagents with a non- or weakly-coordinating anion. Treatment
of 5a with an equimolar amount of HBF4 in ether results
Scheme 5
268
J. Chem. Soc., Dalton Trans., 2001, 266–273

View Article Online
moderately air-stable solids 10a,b (Scheme 5) in nearly quanti-
tative yields. Analogously to 9, the 13C NMR spectra of 10a and
10b exhibit three signals at, respectively, δ 100.4, 96.4, 64.5 (10a)
and δ 100.7, 98.1, 58.1 (10b), supporting again the preferred exo
configuration of the Rh{η3-C6H5C(CH3)C6H5} fragment.
Moreover, the position of the resonance for the CH3 protons of
the benzylic unit at δ 1.76 with the large P–H coupling constant
of 12.4 Hz in the H NMR spectrum of 10a points to an anti
position for this methyl group.
Likewise to the reaction of 5a with [Me3O]BF4, treatment of
proposal of a metal attack, on the other hand the structure of 3
and 4a,b suggests a prefered interaction of the proton with the
carbene. The composition of the products 9, 10a–c and 11/11Ј
obtained from 5a,d,e and either HBF4 or methylating reagents
appears to favor the second possibility. With regard to the con-
version of the (η5-C5H5)Rh to the {η5-C5H4(CHR2)}Rh unit,
we note that upon treatment of [(η5-C5H5)Rh(PMe3)2] with
either PriBr or ButBr mixtures of products are formed among
which the ring-substituted compounds [(η5-C5H4R)RhBr-
(PMe3)2]Br (R = Pri, But) are the dominating species.17 There is
some evidence (from CIDNAP measurements) that in these
processes free radicals are involved.17 The same might be true
for the reaction of [(η5-C5H5)Rh(PPh3)2] with PriI which leads
to [(η5-C5H4Pri)Rh(PPh3)I2].18 It should also be mentioned that
recent investigations by Maitlis and coworkers have shown that
besides the transformation of (η5-C5H5)Rh to (η5-C5H4R)Rh
species the conversion of (η5-C5Me5)Rh to (η5-C5Me4RЈ)Rh
complexes (where RЈ is a functionalized alkyl) is also possible,
in this case an acid–base-type interaction being the important
step.19
1
the same starting material with methyl triflate yields the
Ϫ
CF3SO3 salt of the cation [(η5-C5H5)Rh{η3-C6H5C(CH3)-
C6H5}(PPri3)]ϩ. The spectroscopic data of the corresponding
salt 10c with CF3SO3Ϫ as the anion are quite similar to those of
10a and deserve no further comment.
The protonation of carbene complex 5e containing a carbene
ligand with two different aryl groups at the carbene carbon
atom proceeds analogously to that of 5a. Owing to the 1H
and 13C NMR data of the cation of 11, it cannot be decided
whether the phenyl or the p-tolyl unit is involved in the
π-bonding. There is no doubt, however, that only one isomer, 11
or 11Ј, is formed and that at room temperature in CD2Cl2 as
solvent no conversion of 11 to 11Ј or vice versa occurs.
Experimental
In contrast to HI and other electrophilic substrates, iodine
does not react with 5a or 5d by preserving the rhodium–carbon
bond. Instead the carbene ligand is eliminated and the diiodo-
rhodium() complexes 12a and 12b are formed (Scheme 6).
All experiments were carried out under an atmosphere of argon
by Schlenk techniques. The starting materials 1,16 216 and
5a–e1,16 were prepared as described in the literature. NMR
spectra were recorded at room temperature on Bruker AC 200
and Bruker AMX 400 instruments, and IR spectra on a Perkin-
Elmer 1420 or an IFS 25 FT-IR infrared spectrometer. Melting
points were measured by DTA. Abbreviations used: s, singlet;
d, doublet; t, triplet; sept, septet; m, multiplet; br, broadened
signal; coupling constants J in Hz.
Preparations
[(ꢀ5-C5H5)RhCl(CHPh2)(CO)] 3. A solution of compound 1
(68 mg, 0.19 mmol) in pentane (10 cm3) was treated dropwise
with a 0.5 M solution of HCl in benzene (375 µL, 0.19 mmol)
and stirred for 30 min at room temperature. The solvent was
removed in vacuo, and the oily residue was dissolved in ether (3
cm3). With pentane (2 cm3) a red solid was precipitated, which
was separated from the mother liquor, washed several times
with 3 cm3 portions of pentane and dried: yield 58 mg (78%);
mp 98 ЊC (decomp.) (Found: C, 57.61; H, 4.31. C19H16ClORh
Scheme 6
The phosphine derivative 12a was already known and had been
prepared from [(η5-C5H5)Rh(C2Ph2)(PPri3)] and iodine.15 With
regard to the formation of 12b from 5d and I2, it is quite
remarkable that the Rh–C and not the Rh–Sb bond is split. By
taking the lability of various triisopropylstibinerhodium
compounds into consideration,1,10,16 this result has not been
anticipated.
requires: C, 57.24; H, 4.05%). IR (KBr): ν(CO) 1975 cmϪ1
.
NMR (C6D6): δH (400 MHz) 7.65 (4 H, m, ortho-H of C6H5),
7.36 (2 H, m, para-H of C6H5), 6.99 (4 H, m, meta-H of C6H5),
5.61 [1 H, d, J(Rh,H) 3.7, CHPh2], 4.80 [5 H, d, J(Rh,H) 0.7,
C5H5]. EI MS (70 eV): m/z 399 (Mϩ, 0.2), 362 (Mϩ Ϫ HCl, 0.5),
335 (C5H5RhCHPh2ϩ, 0.6), 196 (C5H5RhCOϩ, 0.9), 168
(RhC5H5ϩ, 16.0), 167 (CHPh2ϩ, 100.0%).
Conclusions
The work presented in this paper has shown that the reactivity
of the half-sandwich-type carbenerhodium() complexes [(η5-
C H )Rh(᎐CR )(L)] (R = aryl) toward Brønsted acids HX with
X = Cl, Br, I and CF3CO2 is, as far as the initial step of the
᎐
5
5
2
[(ꢀ5-C5H5)RhCl(CHPh2)(PMe3)] 4a. A solution of com-
pound 2 (63 mg, 0.15 mmol) in pentane (10 cm3) was treated
dropwise with a 0.5 M solution of HCl in benzene (300 µL, 0.15
mmol). In the time of mixing, a change of color from violet to
red occurred. The solvent was removed in vacuo, and the oily
residue was dissolved in ether (3 cm3). With pentane (2 cm3) a
red solid was precipitated, which was separated from the
mother liquor, washed several times with 3 cm3 portions of
pentane and dried: yield 58 mg (87%); mp 64 ЊC (decomp.)
(Found: C, 56.13; H, 5.69. C21H25ClPRh requires C, 56.47; H,
5.64%). NMR (C6D6): δH (200 MHz) 8.01 (4 H, m, ortho-H of
C6H5), 7.10 (2 H, m, para-H of C6H5), 6.98 (4 H, m, meta-H of
C6H5), 5.34 [1 H, dd, J(Rh,H) = J(P,H) 3.5, CHPh2], 4.59 (5 H,
br s, C5H5), 0.89 [9 H, d, J(P,H) 10.7, PCH3]; δC (50.3 MHz)
156.1, 149.8 (both s, ipso-C of C6H5), 131.9, 129.3, 127.1, 126.7,
124.9, 123.8 (all s, ortho-, meta- and para-C of C6H5), 90.3 [dd,
J(Rh,C) = J(P,C) 3.6, C5H5], 42.4 [dd, J(Rh,C) 19.7, J(P,C)
10.1, CHPh2], 16.6 [d, J(P,C) 32.4, PCH3]; δP (81.0 MHz) 9.4
reaction is concerned, similar to that of the vinylidene counter-
parts [(η5-C H )Rh(᎐C᎐CHR)(L)] (R = alkyl, aryl).5 The
᎐ ᎐
5
5
important and noteworthy difference is that, provided a bulky
phosphine such as PPri3 is linked as an ancillary ligand to the
metal centre, the primary product formed by addition of HX to
the Rh᎐C double bond is extremely labile and reacts to give the
᎐
ring-substituted isomer [{η5-C5H4(CHR2)}RhHX(PPri3)]. To
facilitate this process, obviously the donor strength of the
phosphine does not play a decisive role since the isolated PMe3
compounds [(η5-C5H5)RhX(CHPh2)(PMe3)] with X = Cl and
CF3CO2 do not rearrange to the corresponding {η5-C5H4-
(CHPh2)}Rh derivatives.
The question whether the electrophile prefers to attack the
metal centre or the carbene carbon atom remains to be
answered. While on one hand the similarity between the start-
ing materials 1, 2, 5a–e and the related carbonyl and ethene
complexes [(η5-C5H5)Rh(L)(PR3)] (L = CO, C2H4) supports the
J. Chem. Soc., Dalton Trans., 2001, 266–273
269

View Article Online
[d, J(Rh,P) 154.5]. EI MS (70 eV): m/z 447 (Mϩ, 0.3), 411
(Found: C, 56.01; H, 6.27. C27H37BrPRh requires: C, 56.36; H,
ϩ
(Mϩ Ϫ Cl, 0.2), 410 (Mϩ Ϫ HCl, 1.8), 244 (C5H5RhPMe3
,
6.48%). IR (Nujol): ν(RhH) 2018 cmϪ1. NMR (C6D6): δH (200
MHz) 7.51 (4 H, m, ortho-H of C6H5), 7.21–7.02 (6 H, m,
meta- and para-H of C6H5), 5.96 [1 H, d, J(Rh,H) 2.4, CHPh2],
5.17, 5.04, 4.55, 4.39 [1 H each, all br s, C5H4(CHPh2)], 2.01
(3 H, m, PCHCH3), 0.96 [9 H, dd, J(P,H) 15.5, J(H,H) 7.2,
PCHCH3], 0.95 [9 H, dd, J(P,H) 15.1, J(H,H) 7.0, PCHCH3],
Ϫ12.50 [1 H, dd, J(Rh,H) 35.7, J(P,H) 13.4, RhH]; δC (50.3
MHz) 143.9 (s, ipso-C of C6H5), 143.7 [d, J(Rh,C) 1.9, ipso-C
of C6H5], 130.2, 130.0, 128.8, 128.3, 127.8, 126.6 (all s, ortho-,
meta- and para-C of C6H5), 122.6 [dd, J(Rh,C) 4.6, J(P,C) 1.8,
ipso-C of C5H4(CHPh2)], 93.4 [br s, C5H4(CHPh2)], 86.0 [dd,
J(Rh,C) 8.3, J(P,C) 3.7, C5H4(CHPh2)], 81.1, 77.9 [both d,
J(Rh,C) 5.5, C5H4(CHPh2)], 49.2 (s, CHPh2), 27.3 [d, J(P,C)
25.0, PCHCH3], 20.1, 19.8 (both s, PCHCH3); δP (81.0 MHz)
81.7 [d, J(Rh,P) 145.6].
6.4), 168 (RhC5H5ϩ, 98.0), 167 (CHPh2ϩ, 100.0%).
[(ꢀ5-C5H5)Rh(O2CCF3)(CHPh2)(PMe3)] 4b. A solution of
compound 2 (75 mg, 0.18 mmol) in pentane (10 cm3) was treated
at Ϫ78 ЊC with a solution of CF3CO2H (14 µL, 0.18 mmol)
in pentane (3 cm3). In the time of mixing, a change of color
from violet to red and the precipitation of a solid occurred. On
warming to room temperature the reaction mixture was stirred
for 5 min. The solvent was removed in vacuo, the orange-red
solid was washed several times with 3 cm3 portions of pentane
and dried: yield 86 mg (91%); mp 90 ЊC (decomp.) (Found: C,
52.83; H, 4.70. C23H25F3PO2Rh requires: C, 52.69; H, 4.81%).
IR (KBr): ν(C᎐O) 1679 cmϪ1. NMR (C6D6) δH (400 MHz) 7.61
᎐
(4 H, m, ortho-H of C6H5), 7.11 (2 H, m, para-H of C6H5), 6.93
(4 H, m, meta-H of C6H5), 4.79 [1 H, dd, J(Rh,H) = J(P,H) 2.9,
CHPh2], 4.66 [5 H, d, J(Rh,H) 0.9, C5H5], 0.69 [9 H, d, J(P,H)
11.2, PCH3]; δC (100.6 MHz) 163.1 [q, J(F,C) 35.6, O2CCF3],
155.0, 149.1 (both s, ipso-C of C6H5), 131.3, 129.2, 128.7, 126.3,
125.1, 124.4 (all s, ortho-, meta- and para-C of C6H5), 126.3 [q,
J(F,C) = 261.7, O2CCF3], 90.1 [dd, J(Rh,C) = J(P,C) 3.7, C5H5],
47.0 [dd, J(Rh,C) 21.5, J(P,C) 9.1, CHPh2], 15.9 [d, J(P,C)
30.5, PCH3]; δF (376.5 MHz) Ϫ78.2 (s); δP (162.0 MHz) 10.5
[{ꢀ5-C5H4(CHPh2)}RhHI(PPri3)] 6c. A solution of com-
pound 5a (56 mg, 0.11 mmol) in acetone (10 cm3) was treated
with a 7.6 M solution of HI in water (15 µL, 0.11 mmol). In the
time of mixing, a change of color from deep blue to red-brown
occurred. The reaction mixture was concentrated to ca. 5 cm3 in
vacuo and then stored at Ϫ78 ЊC for 3 d. An orange-brown solid
was formed, which was separated from the mother liquor,
washed twice with 5 cm3 portions of pentane and dried: yield 59
mg (84%); mp 80 ЊC (decomp.) (Found: C, 51.98; H, 5.83.
C27H37IPRh requires: C, 52.11; H, 5.99%). IR (Nujol): ν(RhH)
2019 cmϪ1. NMR (C6D6): δH (200 MHz) 7.47 (4 H, m, ortho-H
of C6H5), 7.19–7.02 (6 H, m, meta- and para-H of C6H5), 6.16
(1 H, br s, CHPh2), 5.25, 4.96, 4.81, 4.53 [1 H each, all br s,
C5H4(CHPh2)], 1.97 (3 H, m, PCHCH3), 0.97 [9 H, dd, J(P,H)
13.5, J(H,H) 6.1, PCHCH3], 0.82 [9 H, dd, J(P,H) 14.7, J(H,H)
7.1, PCHCH3], Ϫ12.99 [1 H, dd, J(Rh,H) 33.7, J(P,H) 12.2,
RhH]; δC (100.6 MHz) 144.6, 143.9 (both s, ipso-C of C6H5),
130.0, 129.8, 128.6, 128.5, 126.7, 126.6 (all s, ortho-, meta- and
para-C of C6H5), 119.4 [dd, J(Rh,C) = J(P,C) 3.6, ipso-C of
C5H4(CHPh2)], 94.3 [br s, C5H4(CHPh2)], 85.6 [dd, J(Rh,C) 7.1,
J(P,C) 4.1, C5H4(CHPh2)], 82.6 [d, J(Rh,C) 5.1, C5H4(CHPh2)],
81.8 [d, J(Rh,C) 5.1, C5H4(CHPh2)], 50.1 (s, CHPh2), 28.2 [d,
J(P,C) 24.4, PCHCH3], 20.3, 20.2 (both s, PCHCH3); δP (81.0
MHz) 81.9 [d, J(Rh,P) 146.9].
[d, J(Rh,P) 159.0]. EI MS (70 eV): m/z 524 (Mϩ, 3.2), 411
ϩ
,
(Mϩ Ϫ O2CCF3, 3.0), 244 (C5H5RhPMe3ϩ, 0.3), 168 (RhC5H5
99.0), 167 (CHPh2ϩ, 100.0%).
[{ꢀ5-C5H4(CHPh2)}RhHCl(PPri3)] 6a. Method A. A solution
of compound 5a (119 mg, 0.24 mmol) in acetone (5 cm3) was
treated with a 0.5 M solution of HCl in benzene (481 µL, 0.24
mmol). In the time of mixing, a change of color from deep blue
to orange occurred. The reaction mixture was concentrated to
ca. 0.5 cm3 in vacuo and an orange solid was precipitated with
pentane. This was separated from the mother liquor, washed
twice with 5 cm3 portions of pentane and dried; yield 116 mg
(91%).
Method B. As described in Method A, compound 6a was
prepared from 5a (119 mg, 0.24 mmol) and Me3SiCl (30 µL,
0.24 mmol) in acetone (5 cm3), which contained traces of water;
yield 114 mg (90%).
Method C. A suspension of compound 8 (72 mg, 0.10 mmol)
in pentane (5 cm3) was treated with a solution of C5H5(CHPh2)
in pentane (2 cm3) at room temperature. Within 10 min, a
change of color from red-violet to orange occurred. The reac-
tion mixture was concentrated to ca. 2 cm3 in vacuo, and the
solution was separated from the precipitate at 0 ЊC. The orange
solid was washed with pentane (2 cm3) and dried; yield 49 mg
(92%); mp 56 ЊC (decomp.) (Found: C, 61.20; H, 7.28.
C27H37ClPRh requires: C, 61.08; H, 7.02%). IR (Nujol): ν(RhH)
2019 cmϪ1. NMR (C6D6): δH (400 MHz) 7.53 (4 H, m, ortho-H
of C6H5), 7.20–7.03 (6 H, m, meta- and para-H of C6H5), 5.72
[1 H, d, J(Rh,H) 2.9, CHPh2], 5.12, 5.06, 4.43 [1 H each, all br s,
C5H4(CHPh2)], 4.38 [1 H, d, J(Rh,H) 1.3, C5H4(CHPh2)], 2.01
(3 H, m, PCHCH3), 0.98 [9 H, dd, J(P,H) 14.6, J(H,H) 7.1,
PCHCH3], 0.96 [9 H, dd, J(P,H) 14.0, J(H,H) 7.1, PCHCH3],
Ϫ12.21 [1 H, dd, J(Rh,H) 35.1, J(P,H) 13.8, RhH]; δC (100.6
MHz) 143.6, 143.5 (both s, ipso-C of C6H5), 130.3, 130.1, 128.6,
128.5, 126.7, 126.6 (all s, ortho-, meta- and para-C of C6H5),
124.5 [dd, J(Rh,C) 5.0, J(P,C) 3.0, ipso-C of C5H4(CHPh2)],
92.7 [s, C5H4(CHPh2)], 85.9 [dd, J(Rh,C) 8.9, J(P,C) 3.6,
C5H4(CHPh2)], 81.0 [d, J(Rh,C) = 5.8, C5H4(CHPh2)], 75.4 [d,
J(Rh,C) 6.4, C5H4(CHPh2)], 48.9 (s, CHPh2), 26.7 [d, J(P,C)
24.8, PCHCH3], 20.0, 19.6 (both s, PCHCH3); δP (162.0 MHz)
81.7 [d, J(Rh,P) 145.0].
[{ꢀ5-C5H4(CHPh2)}RhH(O2CCF3)(PPri3)] 6d. This com-
pound was prepared as described for 6c from 5a (54 mg, 0.11
mmol) and CF3CO2H (8 µL, 0.11 mmol) in acetone (10 cm3).
Light orange solid: yield 62 mg (93%); mp 40 ЊC (decomp.)
(Found: C, 56.93; H, 5.89. C29H37F3O2PRh requires: C, 57.24;
H, 6.13%). IR (Nujol): ν(RhH) 2018 cmϪ1. NMR (C6D6):
δH (200 MHz) 7.35 (4 H, m, ortho-H of C6H5), 7.20–7.00 (6 H,
m, meta- and para-H of C6H5), 5.41 [2 H, br s, CHPh2 and
C5H4(CHPh2)], 5.02, 4.60, 4.18 [1 H each, all br s, C5H4-
(CHPh2)], 1.74 (3 H, m, PCHCH3), 0.94 [9 H, dd, J(P,H) 14.8,
J(H,H) 6.9, PCHCH3], 0.81 [9 H, dd, J(P,H) 14.3, J(H,H) 6.9,
PCHCH3], Ϫ11.04 [1 H, dd, J(Rh,H) 35.5, J(P,H) 13.4, RhH];
δC (50.3 MHz) 163.0 [q, J(F,C) 34.2, CO2CF3], 143.6, 143.3
(both s, ipso-C of C6H5), 129.6, 128.7, 128.6, 128.3, 126.8, 126.7
(all s, ortho-, meta- and para-C of C6H5), 123.8 [dd, J(Rh,C) =
J(P,C) 3.2, ipso-C of C5H4(CHPh2)], 115.8 [q, J(F,C) 292.2,
CO2CF3], 94.2 [br s, C5H4(CHPh2)], 81.0 [dd, J(Rh,C) 7.4,
J(P,C) 4.6, C5H4(CHPh2)], 80.1 [d, J(Rh,C) 6.5, C5H4(CHPh2)],
76.2 [d, J(Rh,C) 5.6, C5H4(CHPh2)], 49.9 (s, CHPh2), 25.7 [d,
J(P,C) 24.0, PCHCH3], 19.5, 19.2 (both s, PCHCH3); δF (188.3
MHz) Ϫ73.6 (s); δP (81.0 MHz) 80.5 [d, J(Rh,P) 144.1].
[{ꢀ5-C5H4CH(p-Tol)2}RhHCl(PPri3)] 6e. This compound was
prepared as described for 6a from 5b (61 mg, 0.12 mmol) and
Me3SiCl (15 µL, 0.12 mmol) in acetone (10 cm3), which con-
tained traces of water. Orange solid: yield 56 mg (86%); mp
46 ЊC (decomp.) (Found: C, 62.01; H, 7.18. C29H41ClPRh
[{ꢀ5-C5H4(CHPh2)}RhHBr(PPri3)] 6b. This compound was
prepared as described for 6a from 5a (38 mg, 0.08 mmol) and
Me3SiBr (10 µL, 0.08 mmol) in acetone, which contained traces
of water. Orange solid: yield 39 mg (88%); mp 54 ЊC (decomp.)
requires: C, 62.31; H, 7.39%). IR (Nujol): ν(RhH) 2018 cmϪ1
.
270
J. Chem. Soc., Dalton Trans., 2001, 266–273

View Article Online
NMR (C6D6): δH (400 MHz) 7.47 (4 H, m, ortho-H of
C6H4CH3), 7.00 (4 H, m, meta-H of C6H4CH3), 5.69 [1 H, d,
J(Rh,H) 2.4, CH(p-Tol)2], 5.20, 5.13 (1 H each, both br s,
C5H4CH(p-Tol)2), 4.44 [2 H, br s, C5H4CH(p-Tol)2], 2.12, 2.09
(3 H each, both s, C6H4CH3), 2.04 (3 H, m, PCHCH3), 1.00,
0.98 [9 H each, both dd, J(P,H) 14.1, J(H,H) 7.0, PCHCH3],
Ϫ12.21 [1 H, dd, J(Rh,H) 35.2, J(P,H) 14.1, RhH]; δC (100.6
MHz) 141.0 (s, ipso-C of C6H4CH3), 140.9 [d, J(Rh,C) 1.9, ipso-
C of C6H4CH3), 135.8, 135.7 (both s, para-C of C6H4CH3),
130.1, 130.0, 129.3, 129.2 (all s, ortho- and meta-C of C6H4-
CH3), 124.8 [dd, J(Rh,C) 4.8, J(P,C) 2.4, ipso-C of C5H4CH-
(p-Tol)2], 92.7 [br s, C5H4CH(p-Tol)2], 85.9 [dd, J(Rh,C) 8.6,
J(P,C) 3.8, C5H4CH(p-Tol)2], 81.5 [d, J(Rh,C) 5.7, C5H4CH-
(p-Tol)2], 75.0 [d, J(Rh,C) 6.7, C5H4CH(p-Tol)2], 48.1 [s, CH-
(p-Tol)2], 26.7 [d, J(P,C) 23.8, PCHCH3], 21.1, 21.0 (both s,
C6H4CH3), 20.1, 19.7 (both s, PCHCH3); δP (162.0 MHz) 81.7
[d, J(Rh,P) 145.8].
C6H5), 6.34 [1 H, d, J(Rh,H) 6.2, CHPh2], 5.76 [1 H, d, J(Rh,H)
1.8, C5H4(CHPh2)], 5.48 [1 H, dd, J(Rh,H) = J(H,H) 1.8,
C5H4(CHPh2)], 5.36 [1 H, ddd, J(Rh,H) = J(H,H) = J(P,H) 1.8,
C5H4(CHPh2)], 5.33 [1 H, br s, C5H4(CHPh2)], 2.83 (3 H, m,
PCHCH3), 1.33 [18 H, dd, J(P,H) 14.4, J(H,H) 7.0, PCHCH3];
δC (100.6 MHz) 142.5 [d, J(Rh,C) 2.0, ipso-C of C6H5), 129.7,
128.9, 127.3 (all s, ortho-, meta- and para-C of C6H5), 118.4 [dd,
J(Rh,C) 9.2, J(P,C) 3.1, ipso-C of C5H4(CHPh2)], 93.1 [dd,
J(Rh,C) 4.3, J(P,C) 1.8, C5H4(CHPh2)], 89.0 [dd, J(Rh,C) 5.1,
J(P,C) 2.0, C5H4(CHPh2)], 81.3 [d, J(Rh,C) 7.1, C5H4(CHPh2)],
49.6 [d, J(Rh,C) 2.0, CHPh2], 30.1 [d, J(P,C) 22.4, PCHCH3)],
21.2 [d, J(P,C) 2.0, PCHCH3]; δP (162.0 MHz) 57.1 [d, J(Rh,P)
139.0].
[{ꢀ5-C5H4(CHPh2)}Rh(CF3CO2)2(PPri3)] 7d. This com-
pound was prepared as decribed for 7c from 5a (81 mg, 0.16
mmol) and CF3CO2H (25 µL, 0.33 mmol) in acetone (10 cm3).
Orange solid: yield 103 mg (87%); mp 113 ЊC (decomp.)
(Found: C, 51.71; H, 5.11. C31H36F6O4PRh requires: C, 51.68;
H, 5.04%). NMR (CD2Cl2): δH (400 MHz) 7.35–7.16 (10 H,
m, ortho-, meta- and para-H of C6H5), 5.95 [2 H, ddd,
J(Rh,H) = J(H,H) = J(P,H) 2.0, C5H4(CHPh2)], 5.59 [1 H,
dd, J(Rh,H) = J(H,H) 1.8, C5H4(CHPh2)], 5.33 [1 H, s,
C5H4(CHPh2)], 5.05 [1 H, d, J(Rh,H) 4.7, CHPh2], 2.49 (3 H, m,
PCHCH3), 1.25 [18 H, dd, J(P,H) 14.7, J(H,H) 7.3, PCHCH3];
δC (100.6 MHz) 163.0 [q, J(F,C) 35.6, CO2CF3], 140.3 (s, ipso-C
of C6H5), 129.2, 129.1, 127.6 (all s, ortho-, meta- and para-C of
C6H5), 122.3 [dd, J(Rh,C) 8.1, J(P,C) 4.1, ipso-C of C5H4-
(CHPh2)], 115.4 [q, J(F,C) 289.9, CO2CF3], 87.9 [dd, J(Rh,C)
6.1, J(P,C) 2.0, C5H4(CHPh2)], 76.6 [d, J(Rh,C) 9.2, C5H4-
(CHPh2)], 48.9 [d, J(Rh,C) 2.0, CHPh2], 25.8 [d, J(P,C) 20.3,
PCHCH3)], 19.4 [d, J(P,C) 2.0, PCHCH3); δF (376.5 MHz)
Ϫ74.3 (s); δP (162.0 MHz) 62.4 [d, J(Rh,P) 130.6].
[{ꢀ5-C5H4(CHPh2)}RhCl2(PPri3)] 7a. A solution of com-
pound 5a (112 mg, 0.23 mmol) in acetone (5 cm3), which con-
tained traces of water, was treated with Me3SiCl (57 µL, 0.45
mmol). In the time of mixing, a change of color from deep
blue to red occurred. The reaction mixture was stirred for 1 h
at room temperature and concentrated to ca. 2 cm3 in vacuo.
After the solution had been stored at Ϫ78 ЊC for 24 h, deep red
crystals were formed, which were separated from the mother
liquor, washed with a small quantity of acetone (0 ЊC) and
dried: yield 120 mg (94%); mp 224 ЊC (Found: C, 57.04; H, 6.34.
C27H36Cl2PRh requires: C, 57.36; H, 6.42%). NMR (C6D6):
δH (400 MHz) 7.42 (4 H, m, ortho-H of C6H5), 7.18–7.02 (6 H,
m, meta- and para-H of C6H5), 6.03 [1 H, d, J(Rh,H) 6.6,
CHPh2], 4.84, 4.65 [2 H each, both d, J(Rh,H) 2.0, C5H4-
(CHPh2)], 2.51 (3 H, m, PCHCH3), 1.06 [18 H, dd, J(P,H) 14.2,
J(H,H) 7.0, PCHCH3]; δC (100.6 MHz) 141.7 (s, ipso-C of
C6H5), 130.3, 128.9, 128.3, 127.2 (all s, ortho-, meta- and para-C
of C6H5), 123.1 [br s, ipso-C of C5H4(CHPh2)], 89.8, 79.7 [both
br s, C5H4(CHPh2)], 47.7 (br s, CHPh2), 26.9 [d, J(P,C) 21.7,
PCHCH3)], 20.1 (s, PCHCH3); δP (162.0 MHz) 59.4 [d, J(Rh,P)
135.1].
[{ꢀ5-C5H4CH(p-Tol)2}RhCl2(PPri3)] 7e. This compound was
prepared as described for 7a from 5b (65 mg, 0.12 mmol) and
Me3SiCl (31 µL, 0.25 mmol) in acetone (5 cm3), which con-
tained traces of water. Red crystals: yield 61 mg (83%); mp
81 ЊC (Found: C, 58.84; H, 6.95. C29H40Cl2PRh requires: C,
58.70; H, 6.79%). NMR (CDCl3): δH (400 MHz) 7.15 (4 H, m,
ortho-H of C6H4CH3), 7.03 (4 H, m, meta-H of C6H4CH3), 5.48
[1 H, d, J(Rh,H) 5.0, CH(p-Tol)2], 5.29 [2 H, dd, J(Rh,H) =
J(H,H) 1.9, C5H4CH(p-Tol)2], 4.96 [2 H, ddd, J(Rh,H) =
J(H,H) = J(P,H) 1.9, C5H4CH(p-Tol)2], 2.74 (3 H, m,
PCHCH3), 2.23 (6 H, s, C6H4CH3), 1.26 [18 H, dd, J(P,H) 14.2,
J(H,H) 7.2, PCHCH3]; δC (100.6 MHz) 138.1 (s, ipso-C of
C6H4CH3), 136.3 (s, para-C of C6H4CH3), 129.3, 129.2 (both s,
ortho- and meta-C of C6H4CH3), 125.2 [dd, J(Rh,C) 7.2, J(P,C)
3.3, ipso-C of C5H4CH(p-Tol)2], 88.1 [dd, J(Rh,C) 5.5, J(P,C)
3.1, C5H4CH(p-Tol)2], 80.3 [d, J(Rh,C) 7.6, C5H4CH(p-Tol)2],
46.6 [d, J(Rh,C) 1.9, CH(p-Tol)2], 26.7 [d, J(P,C) 21.9,
PCHCH3], 20.9 (s, C6H4CH3), 20.0 [d, J(P,C) 1.9, PCHCH3]; δP
(162.0 MHz) 59.1 [d, J(Rh,P) 132.2].
[{ꢀ5-C5H4(CHPh2)}RhBr2(PPri3)] 7b. This compound was
prepared as described for 7a from 5a (53 mg, 0.11 mmol) and
Me3SiBr (28 µL, 0.21 mmol) in acetone (5 cm3), which con-
tained traces of water. Red crystals: yield 60 mg (86%); mp
204 ЊC (Found: C, 49.74; H, 5.43; Rh, 16.00. C27H36Br2PRh
requires: C, 49.57; H, 5.55; Rh, 15.73%). NMR (CD2Cl2): δH
(200 MHz) 7.38–7.22 (10 H, m, ortho-, meta- and para-H of
C6H5), 5.93 [1 H, d, J(Rh,H) 5.6, CHPh2], 5.40, 5.08 [2 H each,
both br s, C5H4(CHPh2)], 2.79 (3 H, m, PCHCH3), 1.32 [18 H,
dd, J(P,H) 14.3, J(H,H) 7.2, PCHCH3]; δC (50.3 MHz) 141.7 (s,
ipso-C of C6H5), 129.6, 128.7, 127.1 (all s, ortho-, meta- and
para-C of C6H5), 121.6 [dd, J(Rh,C) 8.4, J(P,C) 3.5, ipso-C of
C5H4(CHPh2)], 90.6 [d, J(Rh,C) 2.6, C5H4(CHPh2)], 80.6 [d,
J(Rh,C) 7.4, C5H4(CHPh2)], 48.0 (s, CHPh2), 28.0 [d, J(P,C)
22.2, PCHCH3)], 20.4 (s, PCHCH3); δP (81.0 MHz) 57.8 [d,
J(Rh,P) 134.8]. MS (FAB): m/z 652 (Mϩ, 1.3), 573 (Mϩ Ϫ Br,
100.0%).
[{ꢀ5-C5H4(CHPh2)}RhCl2(PPh3)] 7f. This compound was
prepared as described for 7a from 5c (54 mg, 0.09 mmol) and
Me3SiCl (23 µL, 0.18 mmol) in acetone (5 cm3), which con-
tained traces of water. Orange-red solid: yield 55 mg (91%); mp
88 ЊC (Found: C, 64.69; H, 4.49. C36H30Cl2PRh requires: C,
64.79; H, 4.53%). NMR (C6D6): δH (200 MHz) 7.85 (6 H, m,
ortho-H of C6H5P), 7.40 (4 H, m, ortho-H of C6H5), 7.18–6.93
(15 H, m, meta- and para-H of C6H5P and C6H5), 6.17 [1 H, d,
J(Rh,H) 5.8, CHPh2], 4.84 [2 H, d, J(Rh,H) 1.8, C5H4(CHPh2)],
4.12 [2 H, br s, C5H4(CHPh2)]; δP (81.0 MHz) 36.0 [d, J(Rh,P)
137.3].
[{ꢀ5-C5H4(CHPh2)}RhI2(PPri3)] 7c. A solution of compound
5a (72 mg, 0.15 mmol) in acetone (10 cm3) was treated with a
7.6 M solution of HI in water (38 µL, 0.30 mmol). In the time
of mixing, a change of color from deep blue to brown occurred.
The reaction mixture was stirred for 1 h at room temperature
and then concentrated to ca. 5 cm3 in vacuo. After the solution
had been stored at Ϫ78 ЊC for 3 d, a deep brown solid was
formed, which was separated from the mother liquor, washed
twice with 5 cm3 portions of pentane and dried: yield 84 mg
(77%); mp 160 ЊC (decomp.) (Found: C, 43.19; H, 4.79.
C27H36I2PRh requires: C, 43.33; H, 4.84%). NMR (CD2Cl2):
δH (400 MHz) 7.40–7.25 (10 H, m, ortho-, meta- and para-H of
[{ꢀ5-C5D4(CHPh2)}RhDCl(PPri3)] 6a-d5. This compound was
prepared as described for 6a (Method A) from 5a-d5 (54 mg,
0.11 mmol) and a 0.5 M solution of HCl in benzene (216 µL,
0.11 mmol). Orange solid: yield 51 mg (88%). NMR (C6D6):
J. Chem. Soc., Dalton Trans., 2001, 266–273
271

View Article Online
δH (200 MHz) 7.52 (4 H, m, ortho-H of C6H5), 7.19–6.99 (6 H,
m, meta- and para-H of C6H5), 5.74 [1 H, d, J(Rh,H) 2.9,
CHPh2], 2.00 (3 H, m, PCHCH3), 0.97, 0.95 [9 H each, both
dd, J(P,H) 14.5, J(H,H) 7.3, PCHCH3]; δP (81.0 MHz) 82.2 [dt,
J(Rh,P) 145.3, J(P,2H) 5.1].
8.00–7.39 (9 H, m, C6H5), 5.03 (5 H, br s, C5H5), 3.90 (1 H, br s,
H2),20 2.85 [3 H, sept, J(H,H) 7.6, SbCHCH3], 1.43, 1.36 [9 H
each, both d, J(H,H) 7.6, SbCHCH3], signal for C6H5C(CH3)Ph
presumably covered by signals of the methyl protons of the
isopropyl groups; δC (100.6 MHz) 141.1 (s, ipso-C of C6H5),
138.3, 133.1, 131.7, 130.2, 128.7, 128.3, 127.8 (all s, ortho-,
meta- and para-C of C6H5 and C3–6), 100.7 [d, J(Rh,C) 6.0, C1
or C7], 98.1 [d, J(Rh,C) 8.0, C1 or C7], 91.4 [d, J(Rh,C) 5.0,
C5H5], 58.1 [d, J(Rh,C) 11.1, C2], 22.8 [s, C6H5C(CH3)Ph], 22.3
(s, SbCHCH3), 20.6 (s, SbCHCH3); δF (188.3 MHz) Ϫ154.9 (s).
[{ꢀ5-C5D4(CHPh2)}RhCl2(PPri3)] 7a-d4. This compound was
prepared as described for 7a from 5a-d5 (57 mg, 0.11 mmol) and
a 0.5 M solution of HCl in benzene (449 µL, 0.22 mmol). Red
solid: yield 60 mg (92%). NMR (C6D6): δH (200 MHz) 7.42
(4 H, m, ortho-H of C6H5), 7.21–7.02 (6 H, m, meta- and
para-H of C6H5), 6.08 [1 H, d, J(Rh,H) = 5.5, CHPh2], 2.47
(3 H, m, PCHCH3), 1.03 [18 H, dd, J(P,H) 14.1, J(H,H) 7.0,
PCHCH3]; δP (81.0 MHz) 59.9 [d, J(Rh,P) 133.3].
[(ꢀ5-C5H5)Rh{ꢀ3-C6H5C(CH3)Ph}(PPri3)]CF3SO3 10c.
A
solution of 5a (111 mg, 0.22 mmol) in pentane/methanol (1:1, 5
cm3) was treated with CF3SO3Me (25 µL, 0.22 mmol) and
stirred for 30 min at room temperature. A change of color from
deep blue to red occurred. The solvent was removed in vacuo,
and the oily residue was washed twice with 5 cm3 portions of
benzene and once with pentane (10 cm3). A deep red solid was
formed, which was dried in vacuo: yield 121 mg (82%); mp 76 ЊC
(decomp.) (Found: C, 53.27; H, 6.09; S, 4.67. C29H39F3O3PRhS
[(ꢀ5-C5H5)Rh(ꢀ3-C6H5CHPh)(PPri3)]BF4 9. A solution of 5a
(66 mg, 0.13 mmol) in ether (10 cm3) was treated with a 54%
solution of HBF4 in ether (18 µL, 0.13 mmol). In the time of
mixing, a change of color from deep blue to red occurred and a
deep red solid precipitated. The solid was separated from the
mother liquor and dissolved at Ϫ20 ЊC in CH2Cl2 (2 cm3). Addi-
tion of ether (10 cm3) led to the formation of a deep red micro-
crystalline solid, which was separated from the mother liquor,
washed with small quantities of ether and dried: yield 75 mg
(97%); mp 100 ЊC (decomp.) (Found: C, 55.63; H, 6.36. C27H37-
BF4PRh requires: C, 55.69; H, 6.40%). NMR: δH (CD3NO2, 200
MHz) 7.86–7.38 (9 H, m, C6H5), 5.00 [5 H, dd, J(Rh,H) =
J(P,H) 0.8, C5H5], 3.53 [1 H, br d, J(P,H) 9.6, H2],20 2.54 [3 H,
sept, J(H,H) 7.1, PCHCH3], 2.09 (1 H, br s, H7), 1.47 [18 H, dd,
J(P,H) 13.9, J(H,H) 7.1, PCHCH3]; δC (CD3OD, 100.6 MHz)
144.5 (s, ipso-C of C6H5), 130.2, 130.0, 129.9, 129.7, 129.6,
128.4, 128.0 (all s, ortho-, meta- and para-C of C6H5 and C3–6),
96.1 (s, C1), 93.9 [dd, J(Rh,C) 4.8, J(P,C) 1.9, C5H5], 87.3 [dd,
J(Rh,C) 4.8, J(P,C) 1.9, C7], 64.5 [dd, J(Rh,C) 11.4, J(P,C) 4.8,
C2], 20.5 [d, J(P,C) 35.2, PCHCH3], 19.9 [d, J(P,C) 4.8,
PCHCH3]; δF (CD3NO2, 188.3 MHz) Ϫ155.2 (s); δP (CD3NO2,
81.0 MHz) 54.1 [d, J(Rh,P) 154.5]. MS (FAB): m/z 495 (Mϩ,
100.0), 335 (Mϩ Ϫ PPri3, 55.1), 328 (Mϩ Ϫ C6H5CHPh, 57.9),
167 (C6H5CHPhϩ, 19.3%).
requires: C, 52.89; H, 5.97; S, 4.87%). IR (Nujol): ν(S᎐O) 1275
᎐
cmϪ1. NMR (CD2Cl2): δH (400 MHz) 7.80–7.38 (9 H, m, C6H5),
4.87 (5 H, s, C5H5), 3.46 [1 H, d, J(P,H) 10.0, H2],20 2.43 (3 H, m,
PCHCH3), 1.43 [21 H, br m, C6H5C(CH3)Ph and PCHCH3];
δF (376.5 MHz) Ϫ78.6 (s); δP (162.0 MHz) 52.1 [d, J(Rh,P)
155.3].
Reaction from 5e with HBF4. Compound 11 (or 11Ј, see
Scheme 5) was prepared as described for 9 from 5e (69 mg, 0.14
mmol) and a 54% solution of HBF4 in ether (19 µL, 0.14
mmol). Red solid: yield 74 mg (91%); mp 38 ЊC (decomp.)
(Found: C, 56.19; H, 6.43. C28H39BF4PRh requires: C, 56.40; H,
6.59%). Molar conductivity: Λ (CH3NO2) 66 cm2 ΩϪ1 molϪ1
.
NMR (CD2Cl2): δH (400 MHz) 7.68–7.18 (8 H, m, C6H5 and
C6H4), 4.85 (5 H, br s, C5H5), 3.43 [1 H, d, J(P,H) 9.7, H2],20 2.39
[3 H, sept, J(H,H) 7.0, PCHCH3], 2.28 (3 H, br s, C6H4CH3),
1.42 [18 H, dd, J(P,H) 14.1, J(H,H) 7.0, PCHCH3], signal for H7
presumably covered by the signal for C6H4CH3; δC (100.6 MHz)
139.1 (s, ipso-C of C6H4CH3), 135.6 (s, para-C of C6H4CH3),
130.7, 130.5, 130.0, 129.3, 129.2, 127.9 (all s, ortho- and meta-C
of C6H4CH3 and C3–6), 92.8 (br s, C1), 92.5 [dd, J(Rh,C) 3.8,
J(P,C) 1.9, C5H5], 88.2 [dd, J(Rh,C) 8.6, J(P,C) 2.9, C7], 63.3
[dd, J(Rh,C) 11.4, J(P,C) 5.7, C2], 27.7 [d, J(P,C) 21.0,
PCHCH3], 20.3 (s, C6H4CH3), 19.9 (br s, PCHCH3); δF (376.5
MHz) Ϫ150.8 (s); δP (162.0 MHz) 51.9 [d, J(Rh,P) 157.7].
[(ꢀ5-C5H5)Rh{ꢀ3-C6H5C(CH3)Ph}(PPri3)]BF4 10a. A solution
of 5a (76 mg, 0.15 mmol) in ether/methanol (1:1, 10 cm3) was
treated with Meerwein’s salt [Me3O]BF4 (23 mg, 0.15 mmol)
and stirred for 10 min at room temperature. A change of color
from deep blue to red occurred. The solvent was removed
in vacuo, and the residue was dissolved at Ϫ20 ЊC in CH2Cl2
(2 cm3). Addition of ether led to the precipitation of a deep red
solid, which was separated from the mother liquor, washed with
small quantities of ether and dried: yield 83 mg (91%); mp
125 ЊC (decomp.) (Found: C, 56.38; H, 6.51. C28H39BF4PRh
requires: C, 56.40; H, 6.59%). NMR: δH (CD3NO2, 400 MHz)
7.85–7.37 (9 H, m, C6H5), 4.99 (5 H, br s, C5H5), 3.33 (1 H, br s,
H2),20 2.74 (3 H, m, PCHCH3), 1.76 [3 H, d, J(P,H) 12.4,
C6H5C(CH3)Ph], 1.42 [18 H, dd, J(P,H) 16.4, J(H,H) 7.2,
PCHCH3]; δC (CD3OD, 100.6 MHz) 144.5 (s, ipso-C of C6H5),
130.2, 130.0, 129.8, 129.6, 129.5, 128.4, 128.0 (all s, ortho-,
meta- and para-C of C6H5 and C3–6), 100.4 [dd, J(Rh,C) 5.7,
J(P,C) 2.9, C1 or C7], 96.4 [dd, J(Rh,C) 5.7, J(P,C) 2.9, C1 or C7],
93.9 [dd, J(Rh,C) 4.8, J(P,C) 1.9, C5H5], 64.5 [dd, J(Rh,C) 12.4,
J(P,C) 4.8, C2], 28.4 [d, J(P,C) 21.0, C6H5C(CH3)Ph], 20.5
[d, J(P,C) 34.3, PCHCH3], 19.9 [d, J(P,C) 4.8, PCHCH3];
δF (CD3NO2, 376.5 MHz) Ϫ152.2 (s); δP (CD3NO2, 162.0 MHz)
52.4 [d, J(Rh,P) 154.9].
[(ꢀ5-C5H5)RhI2(PPri3)] 12a. A solution of 5a (40 mg, 0.08
mmol) in pentane (10 cm3) was treated at Ϫ78 ЊC with a solu-
tion of iodine (21 mg, 0.08 mmol) in pentane (10 cm3). A rapid
precipitation of a red-brown solid occurred. The solvent was
removed in vacuo, and the residue was dissolved in acetone/
pentane (1:3, 10 cm3). Upon storing at Ϫ60 ЊC for 2 d a red-
brown solid was formed, which was separated from the mother
liquor, washed three times with 5 cm3 portions of pentane and
dried: yield 44 mg (94%). The product was characterized by
1
comparison of the H and 31P NMR data with those of an
authentic sample.15
[(ꢀ5-C5H5)RhI2(SbPri3)] 12b. This compound was prepared
as described for 12a from 5d (42 mg, 0.07 mmol) and iodine
(18 mg, 0.07 mmol) in pentane (20 cm3). Red-brown solid:
yield 46 mg (95%); mp 70 ЊC (decomp.) (Found: C, 24.74;
H, 4.06. C14H26I2RhSb requires: C, 24.99; H, 3.89%). NMR:
δH (C6D6, 200 MHz) 4.94 (5 H, br s, C5H5), 2.39 [3 H, sept,
J(H,H) 7.3, SbCHCH3], 1.17 [18 H, d, J(H,H) 7.3, SbCHCH3];
δC (acetone-d6, 100.6 MHz) 86.3 [d, J(Rh,C) 6.0, C5H5], 24.7
(s, SbCHCH3)], 22.6 (s, SbCHCH3).
[(ꢀ5-C5H5)Rh{ꢀ3-C6H5C(CH3)Ph}(SbPri3)]BF4 10b. This
compound was prepared as described for 10a from 5d (78 mg,
0.13 mmol) and [Me3O]BF4 (20 mg, 0.13 mmol) in ether/
methanol (1:1, 10 cm3). Red solid: yield 81 mg (88%); mp
107 ЊC (decomp.) (Found: C, 48.87; H, 5.69. C28H39BF4SbRh
requires: C, 48.95; H, 5.72%). NMR (CD3NO2): δH (400 MHz)
Crystallography
Single crystals of 7a were grown from acetone (Ϫ20 ЊC); crystal
272
J. Chem. Soc., Dalton Trans., 2001, 266–273

View Article Online
340, 161; H. Werner, J. Wolf, G. Müller and C. Krüger,
size 0.40 × 0.25 × 0.08 mm, monoclinic, space group Cc (no. 9),
a = 8.865(2), b = 23.214(2), c = 13.172(3) Å, β = 106.85(1)Њ,
V = 2594(1) Å3, Dc = 1.447 g cmϪ3; max. 2Θ = 58Њ (Mo-Kα,
λ = 0.71073 Å, graphite monochromator, ω/Θ-scan, Zr filter
with factor 16.4, T = 173(2) K), 3624 reflections scanned, 3624
unique [R(int) = 0.0000], 3488 observed [I > 2σ(I)], Lorentz-
polarization and empirical absorption corrections (ψ-scans,
min. transmission 89.48%) direct methods (SHELXS-86),21
290 parameters, reflex/parameter ratio 12.5, R1 = 0.0284,
J. Organomet. Chem., 1988, 342, 381; A. Höhn and H. Werner,
Chem. Ber., 1988, 121, 881; H. Werner, F. J. Garcia Alonso, H. Otto,
K. Peters and H. G. von Schnering, Chem. Ber., 1988, 121,
1565; U. Brekau and H. Werner, Organometallics, 1990, 9, 1067;
H. Werner, U. Brekau and M. Dziallas, J. Organomet. Chem., 1991,
406, 237.
6 U. Herber, E. Bleuel, O. Gevert, M. Laubender and H. Werner,
Organometallics, 1998, 17, 10.
7 R. Feser and H. Werner, J. Organomet. Chem., 1982, 233, 193.
8 H. Werner and R. Feser, J. Organomet. Chem., 1982, 232, 351.
9 P. Schwab, Ph.D. Thesis, Universität Würzburg, 1994; H. Werner,
J. Organomet. Chem., 1995, 500, 331.
10 E. Bleuel, Ph.D. Thesis, Universität Würzburg, 2000.
11 H. Werner, J. Wolf and A. Höhn, J. Organomet. Chem., 1985, 287,
395.
wR2 = 0.0675, residual electron density 0.673/Ϫ0.813 e ÅϪ3
.
CCDC reference number 186/2295.
See http://www.rsc.org/suppdata/dt/b0/b008354m/ for crys-
tallographic files in .cif format.
12 R. P. Hughes, T. L. Husebo, A. L. Rheingold, L. M. Liable-Sands
and G. P. A. Yap, Organometallics, 1997, 16, 5.
13 C. K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, 1976.
Acknowledgements
We thank the Deutsche Forschungsgemeinschaft (SFB 347)
and the Fonds der Chemischen Industrie for financial support,
the latter in particular for a Ph.D. grant (to P. S.). We are also
grateful to Mrs R. Schedl and Mr C. P. Kneis (DTA measure-
ments and elemental analyses), to Dr W. Buchner and Mrs
M.-L. Schäfer (NMR spectra), to Dr G. Lange and Mr F.
Dadrich (mass spectra), and to Degussa AG (for gifts of
chemicals).
14 T. Braun, O. Gevert and H. Werner, J. Am. Chem. Soc., 1995, 117,
7291.
15 H. Werner, J. Wolf, U. Schubert and K. Ackermann, J. Organomet.
Chem., 1986, 317, 327.
16 H. Werner, P. Schwab, E. Bleuel, N. Mahr, B. Windmüller and
J. Wolf, Chem. Eur. J., 2000, 6, 4461.
17 R. Feser, Ph.D. Thesis, Universität Würzburg, 1981; H. Werner,
R. Feser and J. Wolf, manuscript in preparation.
18 Y. Wakatsuki and H. Yamazaki, J. Organomet. Chem., 1974, 64,
393.
19 O. V. Gusev, A. Z. Rubezhov, J. A. Miguel-Garcia and P. M. Maitlis,
Mendeleev Commun., 1991, 21; J. Miguel-Garcia, H. Adams,
N. A. Bailey and P. M. Maitlis, J. Chem. Soc., Dalton Trans., 1992,
131.
References
1 P. Schwab, N. Mahr, J. Wolf and H. Werner, Angew. Chem., 1993,
105, 1498; P. Schwab, N. Mahr, J. Wolf and H. Werner, Angew.
Chem., Int. Ed. Engl., 1993, 32, 1480; H. Werner, P. Schwab,
E. Bleuel, N. Mahr, P. Steinert and J. Wolf, Chem. Eur. J., 1997, 3,
1375.
20 For assignment of protons and carbon atoms see below.
2 E. Bleuel, B. Weberndörfer and H. Werner, J. Organomet. Chem.,
2000, in press.
3 For definition see: D. F. Shriver, Acc. Chem. Res., 1970, 3, 231.
4 H. Werner, Angew. Chem., 1983, 95, 932; H. Werner, Angew. Chem.,
Int. Ed. Engl., 1983, 22, 927.
5 J. Wolf and H. Werner, J. Organomet. Chem., 1987, 336, 413; J. Wolf,
R. Zolk, U. Schubert and H. Werner, J. Organomet. Chem., 1988,
21 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
J. Chem. Soc., Dalton Trans., 2001, 266–273
273