A series of new fluororhodium(I) complexes

Article abstract of DOI:10.1039/a900440h

The reaction of [Rh{η²-O₂S(O)CF₃}(PPrⁱ ₃)₂] 1 with terminal alkynes RC≡CH (R = Ph or Bu^t) led to the formation of the vinylidene compounds trans-[Rh{η¹-OS(O)₂CF₃}(=C=CHR)(PPr ⁱ₃)₂] 2a,2b, which on treatment with tetrabutylammonium fluoride hydrate or KF gave the fluororhodium(I) complexes trans-[RhF(=C=CHR)(PPrⁱ₃)₂] 3a,3b in ca. 70% yield. An alternative route for the preparation of 3a (R = Ph) is based on the reaction of phenylacetylene with the dimer [{Rh(μ-F)(PPrⁱ₃)₂}₂] 4, the latter being obtained from 1 and [NBu₄]F hydrate as starting materials. Compound 4 reacts smoothly with L′ = CO, CNC₆H₃Me₂-2,6, C₂Ph₂ and C₂H₄ to afford the mononuclear complexes trans-[RhF(L′)(PPrⁱ₃)₂], of which that with L′ = C₂H₄ was characterized by X-ray crystallography. In contrast to the hydroxo compound trans-[Rh(OH)(=C=CHPh)(PPrⁱ₃)₂], which on treatment with acids HX (X = CF₃SO₃, CH₃CO₂, PhO or PhC≡C) gave trans-[RhX(=C=CHPh)(PPrⁱ₃)₂], the fluoro derivative 3a reacts only with CF₃SO₃H and PhC≡CH by ligand substitution to yield the corresponding compounds. Acetic acid and phenol interact with 3a via XH ... FRh hydrogen bridges to form 1:1 adducts, of which that with X = CH₃CO₂ rearranges to give trans-[Rh(O₂CMe)(=C=CHPh)(PPrⁱ₃)₂] and probably trans-[Rh(FHF)-(=C=CHPh)(PPrⁱ₃)₂].

Full text of DOI:10.1039/a900440h

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A series of new fluororhodium(I) complexes†
Juan Gil-Rubio, Birgit Weberndörfer 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 15th January 1999, Accepted 12th March 1999
2
i
t
᎐
The reaction of [Rh{η -O S(O)CF }(PPr ) ] 1 with terminal alkynes RC᎐CH (R = Ph or Bu ) led to the formation
᎐
2
3
3 2
of the vinylidene compounds trans-[Rh{η1-OS(O) CF }(᎐C᎐CHR)(PPri ) ] 2a,2b, which on treatment with
᎐ ᎐
᎐ ᎐
2
3
3 2
tetrabutylammonium fluoride hydrate or KF gave the fluororhodium() complexes trans-[RhF(᎐C᎐CHR)(PPri ) ]
3
2
3a,3b in ca. 70% yield. An alternative route for the preparation of 3a (R = Ph) is based on the reaction of
phenylacetylene with the dimer [{Rh(µ-F)(PPri3)2}2] 4, the latter being obtained from 1 and [NBu4]F hydrate as
starting materials. Compound 4 reacts smoothly with LЈ = CO, CNC6H3Me2-2,6, C2Ph2 and C2H4 to afford the
mononuclear complexes trans-[RhF(LЈ)(PPri3)2], of which that with LЈ = C2H4 was characterized by X-ray
crystallography. In contrast to the hydroxo compound trans-[Rh(OH)(᎐C᎐CHPh)(PPri ) ], which on treatment
᎐ ᎐
3
2
i
᎐
with acids HX (X = CF SO , CH CO , PhO or PhC᎐C) gave trans-[RhX(᎐C᎐CHPh)(PPr ) ], the fluoro derivative
᎐ ᎐
3a reacts only with CF SO H and PhC᎐CH by ligand substitution to yield the corresponding compounds.
᎐
3
3
3
2
3 2
᎐
᎐
3
3
Acetic acid and phenol interact with 3a via XH ؒ ؒ ؒ FRh hydrogen bridges to form 1:1 adducts, of which that
with X = CH CO rearranges to give trans-[Rh(O CMe)(᎐C᎐CHPh)(PPri ) ] and probably trans-[Rh(FHF)-
᎐ ᎐
3
2
2
3 2
(᎐C᎐CHPh)(PPri ) ].
᎐ ᎐
3
2
In contrast to the abundance of electron-rich transition metal
complexes containing chloride, bromide and iodide as ligands,
only a small number of compounds with covalent metal–
fluorine bonds have been reported.1 The reason for this could be
first the dearth of anhydrous fluoride-transfer reagents which
are soluble in organic solvents,2 and second the argument
(based on the hard/soft acid/base, HSAB, concept)3 that the
bond between an electron-rich transition metal and fluorine
should be intrinsically weak. However, in contrast to this
hypothesis some recent observations indicate that fluorometal
complexes of d8 metal systems are not particularly unstable
and, in anhydrous dichloromethane or chloroform as solvent,
the affinity of, e.g., rhodium() and palladium() to halide
ligands decreases in the order FϪ > ClϪ > BrϪ > IϪ.4,5 More-
over, it has also been shown that the chemistry of fluorometal
compounds is substantially different from that of analogous
chloro-, bromo- or iodo-metal derivatives,1,6 and that com-
plexes containing M–F bonds could play an important role in
homogeneous catalysis.1,7
Results and discussion
Synthesis of four-co-ordinate fluororhodium(I) complexes
The preparation of the triflato(vinylidene)rhodium() com-
plexes 2a,2b follows the procedure which we recently used to
obtain the analogous tosylatometal derivatives.11 Treatment of
compound 1 with an equimolar amount of the terminal alkyne
᎐
RC᎐CH in acetone at room temperature leads to a partial
᎐
cleavage of the chelate bond and gives the vinylidene complexes
2a,2b (see Scheme 1) in nearly quantitative yield. The green-
Recently, we described the preparation of allenylidene- and
vinylidene-rhodium() compounds with a hydroxo ligand and
illustrated by several examples that the Rh–OH linkage can
easily be cleaved by Brønsted acids.8,9 We also showed that
reactions of square-planar hydroxorhodium complexes with
Scheme 1 L = PPri3.
blue or violet solids have been characterized by elemental
analysis, mass spectra, IR and NMR spectroscopic techniques.
The most typical features are the doublet of triplets at δ 1.51
᎐
᎐
substituted diynes R EC᎐CC᎐CER (R E = Me Si or Ph Sn)
᎐
᎐
3
3
3
3
3
(2a) or Ϫ0.22 (2b) for the ᎐CHR proton in the 1H NMR and the
lead to the formation of binuclear rhodium complexes in which
the two rhodium centers are connected by a naked C4 bridge.9,10
In the present paper we report the synthesis and characteriz-
ation of a series of fluororhodium() complexes with Rh(PPri3)2
as a building block and discuss the reactivity of the correspond-
᎐
low-field resonance (also a doublet of triplets) at δ 301.6 (2a) or
295.7 (2b) for the α-carbon atom of the vinylidene unit in the
13C NMR spectra.
The new fluoro(vinylidene)rhodium() complexes 3a,3b can
be prepared by two different routes, using either 2a,2b or the
fluoro-bridged dimer 4 as the starting material. The triflates
2a,2b react with potassium fluoride in acetone or with
tetrabutylammonium fluoride hydrate in benzene by ligand
exchange to afford the fluoro derivatives 3a,3b in about 70%
yield. These complexes are red-violet, air-sensitive solids which
can be stored at room temperature under argon for days and
ing vinylidene complex trans-[RhF(᎐C᎐CHPh)(PPri ) ] towards
᎐ ᎐
3
2
Brønsted acids.
† Dedicated to Professor Brian F. G. Johnson on the occasion of his
60th birthday. Vinylidene transition-metal complexes. Part 49. Part 48:
H. Werner, B. Windmüller, O. Nürnberg and J. Wolf, Eur. J. Inorg.
Chem., 1999, in the press.
J. Chem. Soc., Dalton Trans., 1999, 1437–1444
1437

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Table 1 Coupling constants (Hz)a for complexes [{RhX(L)2}n]
Compound
1J(RhP) 2J(PP) 2J(PF) Ref.
Ϫ54.0
[{Rh(µ-F)(PPri3)2}2] 4 Ϫ204.7
ϩ168.7
—
—
This work
[{Rh(µ-Cl)(PPri3)2}2]
[{Rh(µ-Cl)(PMe3)2}2]
[{Rh(µ-Cl)(PCy3)2}2]
[RhF(PCy3)2]
198
55
60
16
16
16
15
16
191.3
195.3
206.0
210
165.0
—
[RhCl(PCy3)2]
a Absolute values are given unless a sign is explicitly included.
the 31P and also the 19F NMR spectrum of 4 is rather com-
plicated. The complexity of the spectra, as illustrated in Fig. 1,
originates from the dimeric structure which causes the mag-
netic non-equivalence of the 19F, 31P and 103Rh nuclei in the
molecule. The computer simulation for an AAЈAЉAٞMMЈXXЈ-
spin system, where A = 31P, M = 103Rh and X = 19F, gives an
excellent fitting between the experimental and the calculated
data. The values of 1J(RhP) and 2J(PF) (see Table 1) are similar
to those found in [RhF(PCy3)2].15 Moreover, the coupling
constant 2J(PP) of 4 is in excellent agreement with that of
related dimers such as [{Rh(µ-Cl)(PPri3)2}2] and [{Rh(µ-Cl)-
(PMe3)2}2].16 In this context we note that also for the fluoro-
bridged complexes [{Rh(µ-F)(Ph2P(CH2)nPPh2)}2] (n = 2 or 3)17
complicated NMR spectra have been observed. However, in
this case the 31P NMR spectroscopic data were not discussed in
detail and no 19F NMR data were given.
Similar to [{Rh(µ-Cl)(PPri3)2}2], the corresponding fluoro
complex 4 is also an excellent starting material for the prepar-
ation of square-planar rhodium() compounds of the general
type trans-[RhF(L)(PPri3)2]. The reactions of 4 with CO, 2,6-
dimethylphenyl isocyanide, diphenylacetylene and ethene
afford the mononuclear complexes 6–9 in good yields (Scheme
2). Compounds 6–9 are yellow solids, which can be handled in
Fig. 1 The 19F (a) and 31P-{1H} (b) NMR spectra of complex 4;
observed (up) and simulated (down) using the following coupling con-
stants (Hz): 1J(RhP) = Ϫ204.7, 1J(RhF) = Ϫ42, 2J(FP)trans = ϩ168.7,
2J(FP)cis = ϩ2.6, 2J(FF) = ϩ70.3, 2J(PP) = Ϫ54.0, 2J(RhRh) = 0,
3J(RhP) = Ϫ0.2, 4J(PP) = ϩ0.8 and ϩ0.6.
do not decompose in solution (e.g. in benzene). Attempts to
prepare compound 3a from the related chloro complex trans-
Scheme 2 L = PPri3.
[RhCl(᎐C᎐CHPh)(PPri ) ] and potassium fluoride in acetone
᎐ ᎐
3
2
failed. Even after prolonged stirring no halide exchange took
place. When it was treated with an excess of tetrabutyl-
ammonium fluoride hydrate in benzene only partial substitu-
tion was observed. With regard to the 13C NMR data of the
fluoro(vinylidene) complexes 3a,3b it should be mentioned that
the characteristic resonances for the vinylidene ligand at δ ca.
300 (α-C) and 115 (β-C) show a strong 19F–13C coupling of
89–96 and 14–15 Hz, respectively, in addition to the 103Rh–13C
and 31P–13C couplings which are also observed for the chloro
air for a short period of time and are stable in C6D6 solution for
several days.
Selected IR and NMR spectroscopic data of the four-co-
ordinate complexes 3a,3b and 6–9 are listed in Table 2. In all
cases, the 31P NMR spectra display one doublet of doublets
with a 103Rh–31P coupling constant that seems to be character-
istic for this type of molecule. The 19F NMR spectra of 3a and
6–9 display a doublet of triplets except for the diphenylacet-
ylene derivative 8, for which a broadened doublet is observed.
Since besides the 103Rh–19F coupling observed in the 19F NMR
also the corresponding signal in the 31P NMR spectrum of 8
shows a coupling to the 19F nuclei, we assume that the broad-
ening is due to a dynamic process which does not involve the
cleavage of the Rh–F bond. Upon addition of anhydrous
Na2CO3 to a solution of 8 in C6D6 the 19F NMR spectrum
displays the expected doublet of triplets with the 103Rh–19F and
31P–19F coupling constants shown in Table 2. From this experi-
ment we conclude that in the absence of Na2CO3 the fluoro
ligand of compound 8 may interact via a hydrogen bridge with
traces of a species containing acidic hydrogen. The interaction
with water could be discarded since the addition of some drops
of it to a solution of 8 which was treated previously with
sodium carbonate did not lead to a broadening of the 19F NMR
resonance.
derivatives trans-[RhCl(᎐C᎐CHR)(PPri ) ].12
᎐ ᎐
3
2
The phenylvinylidene complex 3a is not only formed from 2a
by ligand exchange but also upon treatment of the dinuclear
complex 4 with the terminal alkyne. As outlined in Scheme 1,
the formerly unknown compound 4 was obtained from triflate 1
and tetrabutylammonium fluoride hydrate in benzene. The isol-
ated yield of the orange-red, very air-sensitive solid was 74%.
We note that the chloro counterpart of 4 with the composition
[{Rh(µ-Cl)(PPri3)2}2], which was isolated in our laboratory13
and recently structurally characterized by Binger et al.,14 is
not an appropriate starting material for the synthesis of 4. All
attempts to replace the chloride in [{Rh(µ-Cl)(PPri3)2}2] by
fluoride using [NBu4]F hydrate or TlF as the substrate failed.
In contrast to the 31P NMR spectrum of the monomeric
species [RhF(PCy3)2], which displays a doublet of doublets,15
1438
J. Chem. Soc., Dalton Trans., 1999, 1437–1444

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Table 2 Selected IR and NMR data for complexes trans-[RhF(L)(PPri3)2] (ν in cmϪ1; δ in ppm; J in Hz)
Complex
L
ν(RhF)
δ(19F)
1J(RhF)
2J(PF)
δ(31P)
1J(RhP)
3a
3b
6
C᎐CHPh
᎐
469
453
465
458
452
426
Ϫ216.6
Ϫ222.7
Ϫ269.3
Ϫ280.7
Ϫ258.1
Ϫ248.2
13.4
17.2
49.6
47.5
79.3
76.3
19.0
17.2
19.7
20.1
16.6
18.7
45.6
44.8
51.8
50.3
32.5
36.4
144.0
146.6
130.6
137.1
125.5
129.8
᎐
C᎐CHBut a
CO
᎐
7
C᎐NC6H3Me2
᎐
a
᎐
8
9
PhC᎐CPh
᎐
H2C᎐CH2
᎐
a In the presence of Na2CO3.
A comparison of the NMR data of the four-co-ordinate com-
plexes 3a,3b and 6–9 reveals that the values of the 103Rh–19F
coupling constants increase as a function of L in the order
C᎐CHPh < C᎐CHBut Ӷ CNC H Me < CO Ӷ H C᎐CH <
᎐
᎐
᎐
2
6
3
2
2
᎐
PhC᎐CPh (Table 2). In contrast, there is an increase of the
᎐
103Rh–31P coupling constants in the reverse order. Since it has
been observed both by van Gaal and McFarlane and co-
workers18 that in square-planar rhodium() compounds having
two tertiary phosphines in trans disposition the increase in the
effective electronegativity at the metal leads to an increase in the
size of J(RhP), the decrease of the 103Rh–31P coupling con-
stants in the spectra of 3a,3b and 6–9 may be due to a decrease
of the π-acceptor ability of the ligands LЈ by going from the left
to the right in the above-mentioned series. Recent electro-
chemical measurements suggest that in complexes of the type
trans-[RhCl(LЈ)(PPri3)2] the π-acceptor ability decreases in the
Fig. 2 An ORTEP plot of complex 9.
Table 3 Selected bond lengths (Å) and angles (Њ) for complex 9
order CO > C᎐CPh > C H ,19 whereas with respect to carbon
᎐
2
2
4
monoxide and vinylidene both UV photoelectron spectra and
DV-Xα calculations point to a higher π-acceptor ability for
C᎐CH than for CO.20
Rh–F
Rh–C(1)
Rh–C(2)
2.060(3)
2.096(5)
2.103(5)
Rh–P(1)
Rh–P(2)
C(1)–C(2)
2.326(2)
2.328(2)
1.380(8)
᎐
2
The IR spectra of complexes 3a,3b and 6–9 exhibit one
band between 425 and 470 cmϪ1 with medium intensity which is
assigned to the Rh–F stretching frequency. The band lies in the
same region as that of other fluororhodium complexes such as
trans-[RhF(CO)(PCy3)2] (470 cmϪ1), trans-[RhF(C2H4)(PCy3)2]
F–Rh–C(1)
F–Rh–C(2)
F–Rh–P(1)
F–Rh–P(2)
C(1)–Rh–P(1)
C(1)–Rh–P(2)
160.4(2)
161.2(2)
85.71(9)
84.71(9)
93.8(2)
C(2)–Rh–P(1)
C(2)–Rh–P(2)
C(1)–Rh–C(2)
C(1)–C(2)–Rh
C(2)–C(1)–Rh
P(1)–Rh–P(2)
95.6(2)
94.8(2)
38.4(2)
70.5(3)
71.1(3)
169.53(5)
(421 cmϪ1) and trans-[RhF(PhC᎐CPh)(PCy ) ] (462 cmϪ1).15
93.8(2)
᎐
᎐
3
2
Since we assumed that the remarkable stability of complexes
3a,3b and 6–9 could be due to the favorable trans arrangement
of a strong π acceptor (in particular CO, CNR and vinylidene)
and fluoride as a good π-donor ligand,1,21 we became interested
to know whether the combination of fluoride and a very weak
π acceptor such as pyridine or acetonitrile in trans disposition
could also be realized. However, these experiments failed. While
compound 4 did not react with a 10-fold excess of pyridine in
C6D6 at room temperature, upon warming the solution at 50 ЊC
for 5 h a partial reaction was observed. Besides the resonances
of the starting material three new signals appeared in the 31P
NMR spectrum, of which one was due to free triisopropyl-
phosphine and one [a doublet of doublets at δ 37.0 with
2J(PF) = 17.8 and 1J(RhP) = 157.6 Hz] possibly to cis-[RhF-
(py)2(PPri3)].22 The third signal [a doublet at δ 55.9 with
1J(RhP) = 114.5 Hz] could not be assigned. Treatment of 4 with
piperidine or acetonitrile gave a mixture of products which we
were unable to separate by fractional crystallization or chrom-
atographic techniques.
There is a minor difference between the Rh-C bond lengths of 9
[2.096(5) and 2.103(5) Å] and of the analogous chloro complex
trans-[RhCl(C2H4)(PPri3)2] [2.116(2) and 2.128(2) Å],26 which
indicates that in the fluoro compound the bond between ethene
and the metal is somewhat stronger. A larger difference exists
between the C–C distance of the ethene ligand in 9 [1.380(8) Å]
and of the chloro counterpart [1.319(4) Å] which we contribute
to a higher degree of back bonding from rhodium to the olefin
in 9. The co-ordinated fluoride is obviously a better π donor
than chloride and permits a stronger push-pull effect to the π*
orbital of ethene.
Acid–base reactions of the fluoro(vinylidene) complex 3a
In order to compare the basic character of the hydroxo and
fluoro ligands in the vinylidene complexes trans-[RhX-
(᎐C᎐CHPh)(PPri ) ], the reactions of 10 (X = OH) and 3a
᎐ ᎐
3
2
(X = F) with Brønsted acids have been studied. The hydroxo
derivative 10 reacts with CF3SO3H, CH3CO2H, PhOH and
Molecular structure of the ethenerhodium(I) complex 9
᎐
PhC᎐CH in benzene to afford the substitution products 2a,
᎐
11,27 12,9 and 1327 in virtually quantitative yield (Scheme 3).
The molecular structure of complex 9 was determined by
single-crystal X-ray crystallography. The ORTEP23 plot (Fig. 2)
reveals that the ligand sphere around the metal centre is slightly
distorted square-planar with moderate bending of the phos-
phine ligands toward the fluoride. The structure is thus quite
similar to that of the carbonyl complex trans-[RhF(CO)-
(PPh3)2] for which also a non-linear P–Rh–P axis exists.24 The
Rh–F bond length of 9 [2.060(3) Å] (Table 3) is nearly identical
to that of the before-mentioned carbonyl compound [2.046(2)
Å] but significantly shorter than the distances in the tetramer
[{RhF(C2H4)(C2F4)}4], which contains µ3-bridging fluorides.25
Scheme 3 L = PPri3.
J. Chem. Soc., Dalton Trans., 1999, 1437–1444
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If in the same way a solution of complex 3a in C6D6 is treated
with one equivalent of CF3SO3H compound 2a is formed.
However, treatment of 3a with one equivalent of acetic acid
does not lead to the formation of the corresponding acetato
is a weaker Brønsted base than the Rh–OH bond in 10, the
fluoride ligand being completely displaced by CF3SO3H,
partially displaced by CH3CO2H and not displaced by PhOH.
The behaviour of compound 3a toward phenylacetylene
1
complex but yields a new species, the H and 31P NMR data
deserves a special comment. As shown in Scheme 1, the reac-
᎐
(chemical shifts and coupling constants) of which lie between
those of 3a and 11. There are two facts which indicate that on
the NMR timescale a fast exchange is taking place: first, the 1H
and 31P NMR spectra display a single set of signals regardless
of the amount of added acetic acid (from 12 to 200% with
respect to the quantity of 3a), and second, no P–F or F–H
couplings are observed in each case. In the 19F NMR spectrum
a broad singlet appears at δ Ϫ213.9 at room temperature,
which suggests that at least one of the species present in solu-
tion contains a fluoride bonded to rhodium. We assume that an
exchange process as shown in Scheme 4 occurs. An acetic acid
tion of dimer 4 with two equivalents of PhC᎐CH gives, after a
᎐
short period of time, an unstable π-alkyne intermediate 5 (not
isolated) which smoothly isomerizes to the vinylidene complex
3a. When more than two equivalents of the alkyne are added to
a solution of 4 or when 3a is treated with one equivalent of
phenylacetylene, in the 1H and 31P NMR spectra of the reaction
mixture signals corresponding to compound 1327 are observed.
In C6D6, in the absence of a base, after two hours at room
temperature about 80% of the fluororhodium() derivative
remained. However, upon addition of Na2CO3 to this solution
the alkynyl(vinylidene) complex 13 is quantitatively formed.
Compound 3a thus behaves similarly to the acetato derivative
11 which also reacts with phenylacetylene in the presence of a
base to give 13.27
A mechanism that explains the reactivity of complex 3a
᎐
toward PhC᎐CH is represented in Scheme 5. We assume that
᎐
Scheme 4 L = PPri3.
Scheme 5 L = PPri3.
molecule possibly interacts with 3a by forming a hydrogen bond
to the fluoro ligand, the Rh–F bond subsequently breaks to give
the acetato complex and HF, and the free HF molecule is finally
added to the fluoro ligand of another molecule of 3a to give a
compound with a RhFHF unit. We note that recent studies by
Grushin5 as well as by Perutz, Parkin and co-workers28,29 have
confirmed that HF can indeed be trapped by a fluorometal
complex to generate a co-ordinated bifluoride unit.
the initial step consists of the addition of the alkyne to rhodium
forming a five-co-ordinate intermediate with an 18-electron
configuration at the metal centre. Subsequently, the alkyne is
deprotonated by the co-ordinated fluoride to give 13 and HF. In
the absence of a base, the hydrogen fluoride formed at the
beginning of the reaction could interact with the metal-bonded
fluoride, thus decreasing its basicity and slowing the reaction.
The assumption, that the addition of HF to RhF is a reversible
process, is supported by the result that on treatment of a solu-
tion of 0.04 mmol of 3a in 0.4 cm3 of C6D6 with 0.002 mmol of
The fast exchange between the species in equilibrium (see
Scheme 4), which may explain the absence of P–F and F–H
couplings in the NMR spectra of the solution containing 3a
and acetic acid at 20 ЊC, could be slowed by decreasing the
temperature. In the 19F NMR spectrum at Ϫ83 ЊC the broad
resonance observed at room temperature decoalesces into three
signals. The first is a doublet of doublets at δ Ϫ179.1 with coup-
ling constants 1J(FH) = 418 and 2J(FF) = 101 Hz, which may be
assigned to the terminal fluoride of the Rh–FHF ligand.30 The
second signal is a very broad multiplet at δ Ϫ214.8, which prob-
ably corresponds to the fluoro ligand of 3a. The third resonance
is also a broad multiplet at δ Ϫ228.7 with approximately the
same intensity as that of the doublet of doublets at δ Ϫ179.1,
which we tentatively assign to the rhodium-bound fluoride of
1
HF the H and 31P NMR spectra of the reaction mixture dis-
play no F–H or P–F couplings, the position of the signals being
only slightly different to those of 3a. It is conceivable that the
interaction of HF with the co-ordinated fluoride weakens the
Ϫ
Rh–F bond, therefore allowing the HF2 anion to dissociate.
Exchange processes involving co-ordinated and free bifluoride
moieties have been observed in [RuH(FHF)(dmpe)2]28 and
[PdR(FHF)(PPh3)2] (R = Me or Ph),5 respectively.
Conclusion
1
2
the RhFHF unit. The J(FH) and J(FF) values of the signal
for the terminal fluoride indicate that the interaction
MF ؒ ؒ ؒ HF is significantly weaker than in the ruthenium com-
plex [RuH(FHF)(dmpe)2]28 but similar to that in the eight-co-
ordinate molybdenum compound [MoH2F(FHF)(PMe3)4].29
In the presence of one equivalent of PhOH the NMR spectra
of complex 3a undergo only slight changes indicating that
hydrogen bonding between phenol and the fluoro ligand of 3a is
only weak. Therefore, we conclude that the Rh–F bond in 3a
The work presented in this paper describes the preparation,
structural characterization and reactivity of a series of four-
co-ordinate fluororhodium() complexes including the first
representatives with F–Rh᎐C᎐CHR as a molecular chain.
᎐ ᎐
Despite the progress made during the last decade in developing
synthetic routes to organometallic compounds with M–F
bonds,1 the number of those where M = Rh is still quite small.
Previously, van Gaal and co-workers15,31 reported the pre-
paration of a family of three- and four-co-ordinate fluoro-
1440
J. Chem. Soc., Dalton Trans., 1999, 1437–1444

View Article Online
rhodium() complexes mainly with PCy3 as phosphine ligand
by using [{RhF(C8H14)2}n] as the starting material. The most
extensively studied compound, however, is the Vaska-type
derivative trans-[RhF(CO)(PPh3)2], for which not only a high-
resolution low-temperature crystal structure analysis has been
carried out but also density functional theory applied.24 These
data together with those obtained from spectroscopic and elec-
trochemical investigations suggest that in compounds of the
general type trans-[RhX(CO)(PPh3)2] the electron density at the
metal centre increases along the series I < Br < Cl < F.1 The
results presented in this paper are in agreement with these.
With regard to the synthesis of the complexes 3a,3b and 4
it should be noted that until recently the most common way
to form a Rh–F bond was by chloride abstraction with silver
fluoride or a silver salt of a weakly co-ordinating anion
followed by treatment with a fluoride-donor reagent.1 In this
work we have illustrated that an alternative method for
introducing a fluoro ligand in the co-ordination sphere of
rhodium() consists of the displacement of triflate by fluoride,
thereby using tetrabutylammonium fluoride hydrate or KF as
the fluoride source. Work in progress in our laboratory reveals
that this procedure can also be applied to the preparation
of new organo-iridium and -ruthenium complexes containing
M–F bonds and we will report about these studies in due
course.
as starting materials. The acetone solution was brought to dry-
ness in vacuo, the resulting violet solid washed three times with
4 cm3 portions of pentane (ca. Ϫ10 ЊC) and dried in vacuo at
45 ЊC: yield 0.735 g (98%); mp 89 ЊC (decomp.) (Found: C,
45.73; H, 8.15; S, 4.56. C25H52F3O3P2RhS requires C, 45.87; H,
8.01; S, 4.90%). IR (Nujol): ν(C᎐C) 1677, 1653 cmϪ1. NMR
᎐
(C6D6): δH (400 MHz) 2.66 (m, 6 H, PCHCH3), 1.25 [36 H, dvt,
J(HH) = 7.2, N 13.8, PCHCH3], 0.86 [9 H, s, C(CH3)3] and
Ϫ0.22 [1 H, dt, J(RhH) 0.8, J(PH) 3.1 Hz, Rh᎐C᎐CH];
᎐ ᎐
δC (100.6 MHz) 295.7 [dt, J(RhC) 64.7, J(PC) 17.3, Rh᎐C],
᎐
120.7 [q, J(CF) 319.6, CF3], 116.8 [dt, J(RhC) 17.1, J(PC) 6.0
Hz, Rh᎐C᎐C], 31.9 [s, C(CH ) ], 26.4 [s, C(CH ) ], 23.8 (vt, N
᎐ ᎐
3
3
3 3
19.9 Hz, PCHCH3) and 20.3 (s, PCHCH3); δF (376.4 MHz)
Ϫ76.9 (s, CF3); δP (162.0 MHz) 41.7 [d, J(RhP) 136.9 Hz].
EI MS (70 eV): m/z 654 (Mϩ, 0.3), 572 (Mϩ Ϫ ButC2H, 2),
504 (Mϩ Ϫ CF3SO3H, 1) and 422 (Mϩ Ϫ ButC2H Ϫ CF3SO3H,
1%).
trans-[RhF(᎐C᎐CHPh)(PPri ) ] 3a. A solution of compound
᎐ ᎐
3
2
2a, prepared from 1 (0.786 g, 1.37 mmol) and phenylacetylene
(0.152 cm3, 1.39 mmol) in acetone (15 cm3), was treated with
KF (0.200 g, 4.76 mmol). The mixture was stirred for 1 h at
room temperature and then brought to dryness in vacuo. The
residue was extracted three times with 15 cm3 portions of
pentane. The combined extracts were filtered through cotton,
the filtrate was concentrated to ca. 4 cm3 and then stored for 14 h
at Ϫ60 ЊC. Red-violet crystals precipitated, which were washed
three times with 3 cm3 portions of pentane (Ϫ78 ЊC) and dried
in vacuo: yield 0.529 g (71%); mp 52 ЊC (decomp.) (Found: C,
57.18; H, 9.05. C26H48FP2Rh requires C, 57.35; H, 8.89%). IR
Experimental
All reactions were carried out under an atmosphere of argon by
using Schlenk techniques. The starting materials 111 and 109
were prepared by recently published methods. Tetrabutyl-
ammonium fluoride hydrate (98%) was purchased from Aldrich
and used without drying. The NMR spectra were recorded at
room temperature on Bruker AC 200 and AMX 400 instru-
ments and the IR spectra on a Bruker IFS 25 spectrometer.
Abbreviations used: s, singlet; d, doublet; t, triplet; q, quartet;
m, multiplet; vt, virtual triplet; N = 3J(PH) ϩ 5J(PH) or
1J(PC) ϩ 3J(PC). The simulations of the NMR spectra were
performed using the WIN-DAISY program. Melting points
were determined by DTA. Electron impact mass spectra were
measured on Finnigan and MAT 8200 instruments.
(Nujol): ν(C᎐C) 1643, 1623, 1595, 1570, ν(RhF) 469 cmϪ1
.
᎐
NMR (C6D6): δH (400 MHz) 7.21 [2 H, d, J(HH) 7.3, ortho-H
of C6H5], 7.10 [2 H, t, J(HH) 7.3, meta-H of C6H5], 6.84 [1 H, t,
J(HH) 7.3, para-H of C6H5], 2.48 (6 H, m, PCHCH3), 1.68
(1 H, m, Rh᎐C᎐CH), 1.28 [36 H, dvt, J(HH) 6.4, N 13.6 Hz,
᎐ ᎐
PCHCH3]; δC (100.6 MHz) 301.6 [ddt, J(FC) 95.6, J(RhC) 52.3,
J(PC) 15.5, Rh᎐C], 128.5, 127.4, 124.8, 124.3 (all s, C H ), 112.1
᎐
6
5
[ddt, J(FC) = J(RhC) 15.1, J(PC) 5.7, Rh᎐C᎐C], 23.3 (vt, N
᎐ ᎐
19.0 Hz, PCHCH3) and 20.2 (s, PCHCH3); δF (188.3 MHz)
Ϫ216.6 [dt, J(RhF) 13.4, J(PF) 19.0 Hz]; δP (81.0 MHz) 45.6
[dd, J(RhP) 144.0, J(PF) 19.0 Hz]. EI MS (70 eV): m/z 544 (Mϩ,
6), 524 (Mϩ Ϫ HF, 2), 442 (Mϩ Ϫ PhC2H, 14), 422 (Mϩ Ϫ
HF Ϫ PhC2H, 7), 400 (Mϩ Ϫ PhC2H Ϫ C3H6, 12) and 380
(Mϩ Ϫ HF Ϫ PhC2H Ϫ C3H6, 10%).
Preparations
trans-[Rh{ç1-OS(O) CF }(᎐C᎐CHPh)(PPri ) ] 2a. A solution
᎐ ᎐
2
3
3
2
Alternatively, compound 3a was prepared on treatment of a
solution of 4 (0.074 g, 0.084 mmol) in benzene (5 cm3) with
phenylacetylene (0.019 cm3, 0.17 mmol). After the reaction
mixture was stirred for 41 h at room temperature the 31P NMR
spectrum displayed two doublets corresponding to a ca. 3:2
of compound 1 (0.484 g, 0.84 mmol) in acetone (15 cm3) was
treated with phenylacetylene (0.092 cm3, 0.84 mmol) at Ϫ78 ЊC.
The reaction mixture was slowly warmed to room temperature,
stirred for 5 h and then brought to dryness in vacuo. The resi-
due was dissolved in diethyl ether (3 cm3) and the solution
stored at Ϫ20 ЊC for 3 d. A dark green-blue solid precipitated,
which was washed three times with 2 cm3 portions of diethyl
ether (Ϫ20 ЊC) and dried in vacuo: yield 0.466 g (82%); mp
70 ЊC (decomp.) (Found: C, 47.82; H, 7.35; S, 4.91.
C27H48F3O3P2RhS requires C, 48.07; H, 7.17; S, 4.75%). IR
i
᎐
mixture of 3a and trans-[RhF(PhC᎐CH)(PPr ) ] 5. Upon
᎐
3
2
heating the solution for 2.5 h at 50 ЊC the spectroscopic data
revealed that besides small amounts of free PPri3 and OPPri3
only compound 3a was present. The solution was then brought
to dryness in vacuo and worked up as described above to give a
red-violet solid: yield 0.052 g (57%). NMR data for 5 (C6D6): δH
(200 MHz) 8.21 [2 H, d, J(HH) 7.7, ortho-H of C6H5], 7.21–7.00
(Nujol): ν(C᎐C) 1654, 1629, 1594 cmϪ1. NMR (C6D6): δH (200
᎐
MHz) 7.10–6.82 (5 H, m, C6H5), 2.59 (6 H, m, PCHCH3), 1.51
[3 H, m, meta- and para-H of C6H5], 3.92 [1 H, d, J(RhH) 2.0,
[1 H, dt, J(RhH) 0.9, J(PH) 3.1, Rh᎐C᎐CH] and 1.20 [36 H,
᎐
᎐ ᎐
C᎐CH], 2.07 (6 H, m, PCHCH ), 1.29 [18 H, dvt, J(HH) 6.4, N
᎐
3
dvt, J(HH) 7.1, N 14.0 Hz, PCHCH3]; δC (50.3 MHz) 301.6 [dt,
13.2, PCHCH3] and 1.17 [18 H, dvt, J(HH) 6.3, N 12.9 Hz,
PCHCH3]; δP (81.0 MHz) 35.2 [d, J(RhP) 125.5 Hz].
J(RhC) 64.4, J(PC) 16.6, Rh᎐C], 128.7, 128.3, 125.9 (all s,
᎐
C6H5), 124.0 (br s, ipso-C of C6H5), 111.9 [dt, J(RhC) 17.6,
3
trans-[RhF(᎐C᎐CHBut)(PPri ) ] 3b. A solution of compound
J(PC) 5.9 Hz, Rh᎐C᎐C], 24.1 (vt, N 20.2 Hz, PCHCH ), 20.2
᎐ ᎐
᎐ ᎐
3
2
(s, PCHCH3), signal of CF3 carbon atom obscured by other
signals; δF (188.3 MHz) Ϫ77.4 (s, CF3); δp (81.0 MHz) 44.0
[d, J(RhP) 134.8 Hz]. EI MS (70 eV): m/z 674 (Mϩ, 0.7), 572
(Mϩ Ϫ PhC2H, 1) and 422 (Mϩ Ϫ PhC2H Ϫ CF3SO3H, 0.4%).
2b, prepared from 1 (0.258 g, 0.45 mmol) and 3,3-dimethyl-1-
butyne (0.055 cm3, 0.45 mmol) in acetone (7 cm3), was treated
with KF (0.078 g, 1.34 mmol) and stirred for 1.5 h at room
temperature. The solvent was removed in vacuo and the residue
extracted twice with 10 cm3 portions of pentane. The combined
extracts were filtered through cotton, the filtrate was concen-
trated to ca. 2 cm3 and then stored for 24 h at Ϫ60 ЊC. Dark red-
violet crystals precipitated which were washed twice with 2 cm3
trans-[Rh{ç1-OS(O) CF }(᎐C᎐CHBut)(PPri ) ] 2b. This
᎐ ᎐
2
3
3 2
compound was prepared as described for 2a, using 1 (0.657 g,
1.15 mmol) and 3,3-dimethyl-1-butyne (0.142 cm3, 1.15 mmol)
J. Chem. Soc., Dalton Trans., 1999, 1437–1444
1441

View Article Online
portions of pentane (Ϫ78 ЊC) and dried in vacuo: yield 0.155 g
(66%); mp 98 ЊC (Found: C, 54.61; H, 9.98. C24H52FP2Rh
Ϫ280.7 [dt, J(RhF) 47.5, J(PF) 20.1 Hz]; δP (162.0 MHz) 50.3
[dd, J(RhP) 137.1, J(PF) 20.1 Hz]. EI MS (70 eV): m/z 573 (Mϩ,
8) and 413 (Mϩ Ϫ PPri3, 3%).
requires C, 54.96; H, 9.99%). IR (Nujol): ν(C᎐C) 1671, 1645,
᎐
ν(RhF) 453 cmϪ1. NMR: δH (C6D6, 400 MHz) 2.60 (6 H, m,
PCHCH3), 1.35 [36 H, dvt, J(HH) 7.0, N 13.5 Hz, PCHCH3],
i
᎐
trans-[RhF(PhC᎐CPh)(PPr ) ] 8. A solution of compound 4
᎐
3
2
(0.135 g, 0.15 mmol) in benzene (5 cm3) was treated with
diphenylacetylene (0.055 g, 0.31 mmol) at room temperature.
The solution was stirred for 2 h and then brought to dryness
in vacuo. The residue was extracted three times with 4 cm3
portions of pentane. The combined extracts were filtered
through cotton, the filtrate was concentrated to ca. 2 cm3 and
stored for 24 h at Ϫ20 ЊC. Yellow crystals precipitated which
were washed three times with 2 cm3 portions of pentane
(Ϫ20 ЊC) and dried in vacuo: yield 0.141 g (74%); mp 94 ЊC
(decomp.) (Found: C, 61.72; H, 8.74. C32H52FP2Rh requires C,
1.04 [9 H, s, C(CH ) ] and 0.08 (1 H, m, Rh᎐C᎐CH); δ (C D ,
᎐ ᎐
3
3
C
6
6
100.6 MHz) 298.1 [ddt, J(FC) 89.0, J(RhC) 52.1, J(PC) 15.9,
Rh᎐C], 118.4 [ddt, J(FC) = J(RhC) 14.1, J(PC) 4.7, Rh᎐C᎐C],
᎐
᎐ ᎐
32.7 [s, C(CH3)3], 24.8 [s, C(CH3)3], 23.1 (vt, N 17.6 Hz,
PCHCH3) and 20.2 (s, PCHCH3); δF (d8-toluene, 188.3 MHz)
Ϫ222.5 (br s); δF (after treatment with anhydrous Na2CO3, d8-
toluene, 188.3 MHz) Ϫ222.7 [dt, J(RhF) = J(PF) 17.2 Hz]; δP
(d8-toluene, 81.0 MHz) 44.8 [dd, J(RhP) 146.6, J(PF) 17.2 Hz].
EI MS (70 eV): m/z 524 (Mϩ, 4), 504 (Mϩ Ϫ HF, 1), 442
(Mϩ Ϫ ButC2H, 25), 422 (Mϩ Ϫ HF Ϫ ButC2H, 10), 400
(Mϩ Ϫ ButC2H Ϫ C3H6, 20) and 380 (Mϩ Ϫ HF Ϫ ButC2H Ϫ
C3H6, 16%).
Ϫ1
᎐
61.93; H, 8.45%). IR (Nujol): ν(C᎐C) 1870, ν(RhF) 452 cm
.
᎐
NMR (C6D6): δH (400 MHz) 8.37 [4 H, d, J(HH) 7.6, ortho-H
of C6H5], 7.27 [4 H, t, J(HH) 7.6, meta-H of C6H5], 7.07 [2 H, t,
J(HH) 7.6, para-H of C6H5], 2.09 (6 H, m, PCHCH3) and 1.21
[36 H, dvt, J(HH) 6.7, N 12.9 Hz, PCHCH3]; δC (100.6 MHz)
[{Rh(ì-F)(PPri3)2}2] 4. A solution of compound 1 (0.220 g,
0.38 mmol) in benzene (3 cm3) was treated with tetrabutyl-
ammonium fluoride hydrate (solid, 98%, 0.120 g, 0.45 mmol) at
room temperature. The mixture was stirred for 20 min and then
pentane (30 cm3) added. The suspension was stirred for 5 min
and filtered using a cannula equipped with a cotton filter. The
filtrate was brought to dryness in vacuo, the resulting orange-
red solid washed twice with 2 cm3 portions of pentane (Ϫ78 ЊC)
and dried: yield 0.126 g (74%); mp 111 ЊC (decomp.) (Found: C,
48.61; H, 9.62. C36H84F2P4Rh2 requires C, 48.87; H, 9.57%).
NMR (C6D6): δH (400 MHz) 1.98 (12 H, m, PCHCH3) and 1.40
[72 H, dd, J(HH) 7.2, J(PH) 12.0 Hz, PCHCH3]; δC (100.6
MHz) 24.9 (m, PCHCH3) and 20.8 (s, PCHCH3); δF (376.5
MHz) Ϫ349.2 (m, X part of the AAЈAЉAٞMMЈXXЈ spectrum);
δP (162.0 MHz) 68.3 (m, A part of the AAЈAЉAٞMMЈXXЈ
spectrum).
131.3, 130.8, 128.2, 126.4 (all s, C6H5), 81.5 [dt, J(RhC) 16.2,
᎐
J(PC) 2.9 Hz, C᎐C], 23.0 (vt, N 16.2 Hz, PCHCH ) and 20.2
᎐
3
(s, PCHCH3); δF (376.5 MHz) Ϫ257.8 [br d, J(RhF) 80.1 Hz];
δF (after treatment with anhydrous Na2CO3, d8-toluene, 188.3
MHz) Ϫ258.1 [dt, J(RhF) 79.3, J(PF) 16.6 Hz]; δP (81 MHz)
32.5 [dd, J(RhP) 125.5, J(PF) 16.6 Hz]. EI MS (70 eV): m/z 620
(Mϩ, 0.03), 442 ([RhF(PPri3)2]ϩ, 0.02) and 178 (Ph2C2ϩ, 100%).
trans-[RhF(C2H4)(PPri3)2] 9. A slow stream of ethylene was
passed through a solution of compound 4 (0.210 g, 0.24 mmol)
in pentane (15 cm3) for 1 min at room temperature. A change
from orange-red to yellow-orange occurred. After the solution
was stirred for 15 min at room temperature, the solvent was
removed in vacuo, the resulting yellow solid was washed three
times with 2 cm3 portions of pentane (Ϫ20 ЊC) and dried in
vacuo: yield 0.166 g (74%); mp 95 ЊC (decomp.) (Found: C,
50.83; H, 9.43. C20H46FP2Rh requires C, 51.06; H, 9.86%). IR
(Nujol): ν(RhF) 426 cmϪ1. NMR (C6D6): δH (400 MHz) 2.25
(4 H, br s, C2H4), 2.08 (6 H, m, PCHCH3) and 1.27 [36 H, dvt,
J(HH) 6.4, N 12.8 Hz, PCHCH3]; δC (100.6 MHz) 33.8
[d, J(RhC) 15.3 Hz, C2H4], 21.5 (vt, N 16.3 Hz, PCHCH3) and
20.0 (s, PCHCH3); δF (188.3 MHz) Ϫ248.2 [dt, J(RhF) 76.3,
J(PF) 18.7 Hz]; δP (162.0 MHz) 36.4 [dd, J(RhP) 129.8, J(PF)
18.7 Hz]. EI MS (70 eV): m/z 470 (Mϩ, 1), 442 (Mϩ Ϫ C2H4,
3), 400 (Mϩ Ϫ C2H4 Ϫ C3H6, 3) and 380 (Mϩ Ϫ C2H4 Ϫ
C3H6 Ϫ HF, 2%).
trans-[RhF(CO)(PPri3)2] 6. A stream of CO was passed
through a solution of compound 4 (0.208 g, 0.47 mmol) in
pentane (20 cm3) for 30 s at room temperature. A change from
orange-red to pale yellow was observed. After the solution was
stirred for 10 min at room temperature the solvent was removed
in vacuo, the resulting yellow solid washed twice with 3 cm3
portions of pentane (Ϫ20 ЊC) and dried in vacuo: yield 0.165 mg
(75%); mp 154 ЊC (decomp.) (Found: C, 48.27; H, 8.72.
C19H42FOP2Rh requires C, 48.51; H, 9.00%). IR (Nujol): ν(CO)
1934, ν(RhF) 465 cmϪ1. NMR (C6D6): δH (400 MHz) 2.32 (6 H,
m, PCHCH3) and 1.29 [36 H, dvt, J(HH) 7.0, N 13.8 Hz,
PCHCH3]; δC (100.6 MHz) 192.9 [ddt, J(FC) 78.3, J(RhC) 68.1,
J(PC) 15.3 Hz, RhCO], 23.9 (vt, N 19.3 Hz, PCHCH3) and 20.1
(s, PCHCH3); δF (376.5 MHz) Ϫ269.3 [dt, J(RhF) 49.6, J(PF)
19.7 Hz]; δP (162.0 MHz) 51.8 [dd, J(RhP) 130.6, J(PF) 19.7
Hz]. EI MS (70 eV): m/z 470 (Mϩ, 21), 442 (Mϩ Ϫ CO, 4), 422
(Mϩ Ϫ CO Ϫ HF, 9), 400 (Mϩ Ϫ CO Ϫ C3H6, 13) and 380
(Mϩ Ϫ HF Ϫ CO Ϫ C3H6, 10%).
Reactions of compound 10
With trifluoromethanosulfonic acid. In an NMR tube a solu-
tion of compound 10 (0.037 g, 0.068 mmol) in C6D6 (0.4 cm3)
was treated with CF3SO3H (0.072 cm3 of a 0.95 M solution in
diethyl ether, 0.068 mmol) at room temperature. After 15 min
the 1H, 19F and 31P-{1H} NMR spectra of the solution indicated
a quantitative conversion into 2a. In order to isolate compound
2a, the solution was evaporated to dryness and pentane
(15 cm3) and anhydrous Na2CO3 (0.5 g) were added to the resi-
due. The mixture was stirred for 5 min, the solution was filtered
through cotton and the filtrate brought to dryness in vacuo. The
resulting blue-green solid was washed with pentane (2 cm3,
Ϫ78 ЊC) and dried: yield 0.023 g (50%).
trans-[RhF(CNC6H3Me2-2,6)(PPri3)2] 7. A solution of com-
pound 4 (0.571 g, 0.64 mmol) in benzene (20 cm3) was treated
with 2,6-dimethylphenyl isocyanide (0.164 mg, 1.25 mmol) at
room temperature. The solution was stirred for 1 h and then
filtered through cotton. The filtrate was brought to dryness in
vacuo, the resulting yellow solid washed three times with 5 cm3
portions of hexane (0 ЊC) and dried in vacuo. The mother-
liquors were concentrated to ca. 4 cm3 and stored for 5 d at
Ϫ20 ЊC to give a second portion of the yellow solid: yield 0.585
mg (76%); mp 48 ЊC (decomp.) (Found: C, 56.60; H, 8.62; N,
2.64. C27H51FNP2Rh requires C, 56.53; H, 8.96; N, 2.45%). IR
With acetic acid. In an NMR tube a solution of compound
10 (0.042 g, 0.077 mmol) in C6D6 (0.4 cm3) was treated with
acetic acid (30 µL of a 2.6 M solution in C6D6, 0.078 mmol) at
(Nujol): ν(C᎐N) 2038, 2009, ν(RhF) 458 cmϪ1; NMR (C6D6):
room temperature. After 25 min, the H and 31P-{1H} NMR
1
᎐
᎐
δH (400 MHz) 6.76 [3 H, m, C6H3(CH3)2], 2.37 [6 H, s,
spectra of the solution indicated a quantitative conversion to
compound 11,27 which was isolated in the same way as
described for 2a: yield 0.030 g (67%). The corresponding reac-
tions of compound 10 with phenol and phenylacetylene have
been reported.9
C6H3(CH3)2], 2.35 (6 H, m, PCHCH3) and 1.37 [36 H, dvt,
J(HH) 6.8, N 13.2 Hz, PCHCH3]; δC (100.6 MHz) 133.1, 132.4,
128.0, 125.0 [all s, C6H3(CH3)2], 23.9 (vt, N 18.0 Hz, PCHCH3),
20.3 (s, PCHCH3) and 19.1 [s, C6H3(CH3)2]; δF (188.3 MHz)
1442
J. Chem. Soc., Dalton Trans., 1999, 1437–1444

View Article Online
Reactions of compound 3a
Acknowledgements
With trifluoromethanosulfonic acid. In an NMR tube a solu-
tion of compound 3a (0.035 g, 0.064 mmol) in C6D6 (0.4 cm3)
was treated with CF3SO3H (0.067 cm3 of a 0.95 M solution in
diethyl ether, 0.064 mmol) at room temperature. An instant
We thank the Fonds der Chemischen Industrie, the Deutsche
Forschungsgemeinschaft (DFG) (Grant SFB 347) and the
European Commission (Contract ERBFMBICT960698) for
financial support. J. G.-R. is particularly grateful to the EC for
a postdoctoral grant and to the DFG for a research contract.
We are also grateful to Mrs M. L. Schäfer, Dr W. Buchner and
Dr R. Bettermann for NMR spectra, NMR simulations and
valuable discussions, Mrs R. Schedl and Mr C. P. Kneis for
elemental analysis and DTA measurements, Dr G. Lange and
Mr F. Dadrich for mass spectra, and Degussa AG for various
gifts of chemicals.
change from red-violet to dark violet was observed. The 1H, 19
F
and 31P-{1H} NMR spectra of the solution indicated a quant-
itative conversion of 3a into 2a.
With acetic acid. In an NMR tube a solution of compound
3a (0.043 g, 0.079 mmol) in C6D6 (0.4 cm3) was treated with
acetic acid (0.053 cm3 of a 1.5 M solution in C6D6, 0.08 mmol)
at room temperature. After 10 min the NMR spectra were
recorded at room temperature: δH (200 MHz) 11.3 (br s), 7.15–
7.04 (4 H, m, ortho- and meta-H of C6H5), 6.85 [1 H, t, J(HH)
6.9, para-H of C6H5], 2.45 (6 H, m, PCHCH3), 1.88 (3 H, s,
References
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CH CO ), 1.63 [1 H, dt, J(RhH) 1.3, J(PH) 3.1, C᎐CH] and
᎐
3
2
1.25 [36 H, dvt, J(HH) 6.6, N 13.9 Hz, PCHCH3]; δF (188.3
MHz) Ϫ213.9 (br s); δP (81.0 MHz) 45.4 [d, J(RhP) 140.0 Hz].
An analogous experiment was performed using d8-toluene as
solvent in order to measure the NMR spectra at low temper-
ature: δH (400 MHz, Ϫ70 ЊC) 13.9 (br s, CH3CO2H), 12.0 [br d,
J(FH) ca. 420 Hz, FHF–Rh], 7.20–6.93 (5 H, m, C6H5), 2.43
(6 H, br m, PCHCH3), 1.97 (3 H, br s, CH3CO2), 1.68 (1 H, br
m, Rh᎐C᎐CH) and 1.25 (36 H, br m, PCHCH ); δ (376.5
᎐ ᎐
3
F
MHz, Ϫ83 ЊC) Ϫ179.1 [br dd, J(FF) 101, J(FH) 418 Hz, FHF–
Rh], Ϫ214.8 (br m, F–Rh) and Ϫ228.7 (br m, FHF–Rh);
δP (162.0 MHz, Ϫ83 ЊC) 44.4 [br d, J(RhP) 139.0] and 41.2 [br
d, J(RhP) 137.3 Hz].
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Laboratory, Oak Ridge, TN, 1976.
With phenylacetylene. A solution of compound 3a (0.031 g,
0.057 mmol) in C6D6 (0.4 cm3) was treated with phenylacetylene
(0.052 cm3 of a 1.1 M solution in C6D6, 0.057 mmol) and an
excess of anhydrous Na2CO3 (ca. 0.1 g) at room temperature.
The mixture was stirred for 30 min at room temperature which
led to a change from red-violet to green. The solution was then
transferred to an NMR tube. The 1H and 31P-{1H} NMR
spectra indicated a quantitative conversion of 3a into 13.27
Crystallography
Single crystals of complex 9 were grown from pentane (Ϫ25 ЊC).
Crystal data (from 25 reflections, 10 < θ < 15Њ): monoclinic,
space group P21/c (no. 14); a = 19.401(9), b = 8.5915(9),
c = 15.175(7) Å, β = 112.59(1)Њ, V = 2335(2) Å3, Z = 4,
Dc = 1.338 g cmϪ3, µ(Mo-Kα) = 0.868 mmϪ1; crystal size
0.12 × 0.10 × 0.03 mm; Enraf-Nonius CAD4 diffractometer,
graphite monochromator, zirconium filter (factor 16.5);
T = 173(2) K, ω–θ scans, maximum 2θ = 50Њ; 4191 reflections
measured, 3875 independent, 2886 with I > 2σ(I), 3869 used
for refinement. Data reduction was performed with SDP.32
Intensity data were corrected for Lorentz-polarization effects.
Linear decay (loss of intensity 6.5%) and empirical absorption
corrections (ψ scans) were applied (minimum transmission
94.34%).33 The structure was solved by direct methods
(SHELXS 86).34 Atomic co-ordinates and anisotropic thermal
displacement parameters of the non-hydrogen atoms were
refined anisotropically by full-matrix least squares on F2 (241
parameters; SHELXL 93).35 The positions of H(1A), H(1B),
H(2A), and H(2B) could be located in a final Fourier-difference
synthesis and refined isotropically with fixed Ueq. The positions
of the other hydrogen atoms were calculated according to ideal
geometry using the riding method. Conventional R = 0.0405
[for 2888 reflections with I > 2σ(I)] and weighted wR2 = 0.1129
for all 3869 data reflections; reflection-to-parameter ratio 16.05,
residual electron density ϩ0.673/Ϫ0.968.
24 A. Wierzbicki, E. A. Salter, N. W. Hoffman, E. D. Stevens, L. V. Do,
M. S. VanLoock and J. D. Madura, J. Phys. Chem., 1996, 100,
11250.
25 R. R. Burch, R. L. Harlow and S. D. Ittel, Organometallics, 1987, 6,
CCDC reference number 186/1383.
See http://www.rsc.org/suppdata/dt/1999/1437/ for crystallo-
graphic files in .cif format.
982.
26 C. Busetto, A. D’Alfonso, F. Maspero, G. Perego and A. Zazzetta,
J. Chem. Soc., Dalton Trans., 1977, 1828.
J. Chem. Soc., Dalton Trans., 1999, 1437–1444
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Soc., 1996, 118, 7428.
30 See F. Y. Fujiwara and J. S. Martin, J. Am. Chem. Soc., 1974, 96,
7625.
for concurrent X-ray data collection and structure determination,
in Computing in Crystallography, Delft University Press, Delft, 1978,
p. 64.
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Sect. A, 1968, 24, 351.
34 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
35 G. M. Sheldrick, SHELXL 93, A program for crystal structure
refinement, University of Göttingen, 1993.
31 H. L. M. van Gaal, F. L. A. van den Bekerom and J. P. J. Verlaan,
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32 B. A. Frenz, The Enraf-Nonius CAD4 SDP, a real time system
Paper 9/00440H
1444
J. Chem. Soc., Dalton Trans., 1999, 1437–1444