Synthesis and co-ordination chemistry of perfluorovinyl phosphine derivatives. Single crystal structures of PPh(CF=CF2)2, cis-[PtCl2{PPh2(CF=CF2)}2] and [{AuCl[PPh2(CF=CF2</

Article abstract of DOI:10.1039/a806535g

Reaction of perfluorovinyllithium, derived from CF₃CH₂F, with chloro-substituted phosphines generated perfluorovinylphosphines of the type PPh_m(CF=CF₂)_n and P(CF=CF₂)_nCl_m

Full text of DOI:10.1039/a806535g

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Synthesis and co-ordination chemistry of perfluorovinyl phosphine
derivatives. Single crystal structures of PPh(CF᎐CF ) , cis-
᎐
2 2
[PtCl {PPh (CF᎐CF )} ] and [{AuCl[PPh (CF᎐CF )]} ]
᎐
᎐
2
2
2
2
2
2
2
Kulbinder K. Banger,a Russell P. Banham,a Alan K. Brisdon,*a Wendy I. Cross,a
Greame Damant,a Simon Parsons,b Robin G. Pritcharda and Antonio Sousa-Pedraresa
a Department of Chemistry, University of Manchester Institute of Science and Technology,
PO Box 88, Manchester, UK M60 1QD. E-mail: alan.brisdon@umist.ac.uk
b Department of Chemistry, University of Edinburgh, West Mains Road, Edinburgh,
UK EH9 3JJ
Received 19th August 1998, Accepted 24th November 1998
Reaction of perfluorovinyllithium, derived from CF3CH2F, with chloro-substituted phosphines generated perfluoro-
vinylphosphines of the type PPh (CF᎐CF ) and P(CF᎐CF ) Cl (n ϩ m = 3) in high yields. A low-temperature
᎐
᎐
m
2
n
2
n
m
crystal structure determination of the air- and moisture-stable compound PPh(CF=CF2)2 provided the first reported
structural data for any perfluorovinyl-containing material. There is considerable variation in the C–F bond distances
[1.310(4), 1.321(4), 1.353(3) Å] within the perfluorovinyl group in the phosphine. The co-ordination chemistry of
these ligands has been investigated via the synthesis of examples of late transition-metal complexes. The results of
single crystal structural determinations of cis-[PtCl {PPh (CF᎐CF )} ] and [{AuCl[PPh (CF᎐CF )]} ]ؒ0.5CH Cl
᎐
᎐
2
2
2
2
2
2
2
2
2
are reported. In both of these molecules short metal–phosphorus distances [d(Pt–P)av = 2.231(3) and d(Au–P)av
2.217(2) Å] are observed compared with typical distances for similar phosphine complexes. A comparison of
the electronic properties of these ligands with those of other phosphines, halogenophosphines and phosphites
was made on the basis of a spectroscopic investigation of the carbonyl stretching frequencies of the complexes
=
[Mo(CO) {PPh (CF᎐CF ) }] (n ϩ m = 3).
᎐
5
m
2 n
relatively few fluoroalkylphosphine ligands and little co-
ordination chemistry known for them. Even for the very
simplest organofluorophosphine, P(CF3)3, only a relatively few
complexes are known, such as [M(CO)nϪx{(CF3)3P}x] (M = Ni,
n = 4, x = 1–3;11 M = Fe, n = 5, x = 1–312) and one example of
a platinum complex.13
Introduction
Tertiary organophosphine compounds are probably the most
widely studied ligand systems in inorganic chemistry.1 One
reason for this widespread use is the ease with which changes
to the electronic and steric properties of the ligands can be
induced by altering the organic fragments attached to the
phosphorus centre. Such variation is frequently confined to
simple alkyl and aryl substitution, however there has recently
been renewed interest in phosphine ligands containing per-
fluorinated organic fragments.2 Part of this interest has arisen
from the potential these ligands have in solubilising metal
complexes in fluorous solvents, for example by incorporating
long fluorocarbon ‘ponytails’ on the phosphines.3 However, in
order that the presence of the fluorocarbon fragment does not
significantly alter the electronic properties of the phosphorus
donor it has, so far, proved important that a short section of the
alkyl chain closest to the phosphorus is non-fluorinated. By
contrast studies of phosphines containing direct P–F linkages
such as PF3ϪxRx (R = CF3 or Ph)4 show that these ligands act as
strong π acceptors with PF3 acting as an analogue of CO.5
When fluoroorganic groups are present the phosphines are still
good π acceptors, but have a larger, and controllable, steric
demand; the number of examples of such compounds is more
limited. To date much of the interest has been in fluoroaryl-
phosphines6 such as P(C6F5)3 and related systems; this is, in
part, because they, or suitable precursors, are commercially
available. More significantly, in a number of cases metal
complexes containing these ligands have shown examples of
activation of the strong C–F bonds in the phosphine ligand.7
Simple fluoroalkyl systems such as P(CF3)3,8 (C2F5)2PCH2-
The synthesis of a few examples of phosphines containing
fluorovinyl moieties has been reported, including in the early
1960s the synthesis and spectroscopic properties of compounds
of the type P(CF᎐CF ) R (R = alkyl; x ϩ y = 3).14 Most of
᎐
2
x
y
these materials were synthesized via the thermally unstable
perfluorovinyl Grignard reagent obtained from CF ᎐CFX
᎐
2
(X = Cl or Br). In 1978 Horn et al.15 reported the synthesis
of perfluorovinylphosphine compounds by the reaction of C2-
F3Br with methyllithium followed by reaction with chlorophos-
phines. However, these perfluorovinyl systems were obtained
only in very low yields (<2% in some cases) and no structural
data or studies of their co-ordination chemistry were reported.
In fact the halogenofluorocarbons such as CF ᎐CFX (X = Cl or
᎐
2
Br) which in the past have been precursors to these compounds
are now difficult to obtain because of their potentially harmful
effect on the ozone layer.
Recently we reported the synthesis of inorganic perfluoro-
vinyl compounds via the perfluorovinyllithium intermediate
CF ᎐CFϪLiϩ
1
resulting from the treatment of the
᎐
2
chlorofluorocarbon replacement HFC 134a, CF3CH2F, with
2 equivalents of LiBu.16 We have shown that this route is
wide ranging and high yielding and can be used to generate a
number of main group and transition metal perfluorovinyl
compounds by the reaction of metal halides with the transfer
reagent 1. Here we report an extension of this route to the syn-
thesis of perfluorovinylphosphines resulting in their structural
characterisation and an investigation of their co-ordination
chemistry.
9
10
CH2P(C2F5)2 and, very recently, PPh(C2F5)2 have been pre-
pared and are generally limited by the availability of straight-
forward preparative methods. As a consequence there are
J. Chem. Soc., Dalton Trans., 1999, 427–434
427

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Results and discussion
The slow addition of 2 equivalents of n-butyllithium to a
diethyl ether solution of CF3CH2F at Ϫ78 ЊC results in the
formation of the thermally unstable CF ᎐CFϪLiϩ reagent 1 in
᎐
2
good yields. Following a series of experiments under a variety
of conditions it appears that at Ϫ78 ЊC a reaction time of ca.
2 h results in essentially complete conversion of CF3CH2F into
CF ᎐CFϪLiϩ without any appreciable decomposition of the
᎐
2
generated lithium reagent. Compound 1 generated in this way
is stable in diethyl ether or THF solution for up to 24 h at
low temperatures with only minor decomposition being noted,
but raising the temperature to Ϫ45 ЊC results in immediate
and complete decomposition of 1 resulting in a dark coloured,
viscous solution.
Generation of reagent 1 from CF3CH2F is assumed to pro-
ceed via a two step mechanism which can be viewed simplis-
tically as involving deprotonation of the HFC with subsequent
elimination of 1 equivalent of lithium fluoride to yield trifluoro-
ethene which is deprotonated by the second equivalent of
base to generate 1 (Scheme 1). Support for this mechanism has
Fig. 1 (a) The 19F NMR spectrum recorded for a solution of PPh2-
Scheme 1 Reaction scheme for the two-stage, one-pot synthesis of
perfluorovinylphosphines.
(CF᎐CF2) in CDCl3, (b) the labelling system used for NMR spectro-
᎐
scopic data for the perfluorovinyl moiety and (c) the CDCl3 solution-
phase 31P NMR spectrum.
come from the interception of the intermediate tetrafluoroethyl-
lithium species by reaction with tributyltin chloride to generate
CF3CFHSnBu3.17
Perfluorovinylphosphine compounds are obtained by allow-
ing a cold, concentrated diethyl ether or THF solution to react
Unambiguous identification of all of the products was ob-
tained by a combination of elemental analysis, IR and multi-
nuclear (1H, 19F, 31P and 13C) NMR spectroscopy as outlined
in Table 1. The 19F NMR spectra of all these compounds
exhibit doublets of doublets of doublets for each of the three
inequivalent fluorine nuclei of the perfluorovinyl ligand in
distinct regions typical of an AMX spin system, as shown
in Fig. 1(a). By comparison with data previously obtained
for perfluorovinyl complexes19 and the magnitude of typical
coupling constants observed in fluoroolefins (20–90 Hz for gem,
30–60 Hz for cis and 110–130 Hz for trans couplings20) the
signals within the regions δ Ϫ78 to Ϫ85, Ϫ95 to Ϫ110 and
Ϫ168 to Ϫ185 are assigned to Fa, Fb and Fc [Fig. 1(b)]
respectively.
with
the
appropriate
chlorophosphine
compound
(e.g. PClPh2, PPhCl2 and PCl3) whilst maintaining the reactor
temperature at Ϫ100 ЊC. Prior to working up the reaction
samples were withdrawn from the organic phase and monitored
by multinuclear NMR studies to determine the degree of sub-
stitution and extent of reaction. The 19F NMR spectra of these
solutions clearly demonstrate that the HFC has been consumed
since the complex multiplet signals at δ Ϫ64.9 and Ϫ226.5 due
to CF3CH2F18 have been replaced by three sets of doublets of
doublets of doublets within the chemical shift regions typical
of those previously recorded for perfluorovinyl complexes.19
After allowing the reaction mixture slowly to attain room
temperature overnight hexane was added resulting in the
precipitation of the alkali-metal salts which were removed by
filtration. The resulting organic solvents were dried and
removed under vacuum to leave a crude product from which,
by distillation under reduced pressure, the colourless, liquid
perfluorovinylphosphines are obtained in high yield. For the
majority of perfluorovinyl complexes the final yields are around
70%, based on the amount of chlorophosphine used, however
for the tris-substituted perfluorovinylphosphine the final yields
were very much lower. This, in part, appears to be due to the
large amount of heat evolved on reaction of PCl3 with 1, which
results in localised heating of the reaction mixture and
decomposition.
By virtue of the one relatively large magnitude P–F coupling
constant the extent of perfluorovinyl substitution can readily,
and simply, be determined from 31P-{1H} NMR studies. The
spectra obtained for solutions of a mono-perfluorovinyl-
substituted phosphine such as PPh (CF᎐CF ) or P(CF᎐CF )-
᎐
᎐
2
2
2
Cl2 display a basic doublet structure due to coupling between
the phosphorus nucleus and the fluorine nucleus, Fb. Addi-
tional fine structure is visible on each of the components of the
doublet due to coupling with the remaining non-equivalent
fluorine nuclei. In the case of PPh (CF᎐CF ) however, due
᎐
2
2
to similar coupling constants, overlapping of peaks occurs to
produce a doublet of triplets, such as that shown in Fig. 1(c). In
a similar way the 31P NMR spectra of bis-substituted com-
pounds such as PPh(CF᎐CF ) and P(CF᎐CF ) Cl display a
᎐
᎐
2
2
2 2
By varying the stoichiometric ratios of phosphines PPh2Cl,
signal with a basic triplet appearance and that of the tris-
substituted compound, P(CF᎐CF ) , is based on a 1:3:3:1
PPhCl and PCl to reagent 1 the compounds PPh (CF᎐CF ),
᎐
᎐
2
3
2
2
2 3
PPh(CF᎐CF ) , PPh(CF᎐CF )Cl, P(CF᎐CF )Cl , P(CF᎐CF ) -
quartet. We note that under the routine conditions used for
recording NMR spectra we were not able to detect through-
phosphorus coupling corresponding to JFF, or more distant,
᎐
᎐
᎐
᎐
2
2
2
2
2
2 2
Cl and P(CF᎐CF ) were prepared. Those materials without
᎐
2
3
4
P–Cl bonds are air- and moisture-stable liquids and show no
appreciable signs of decomposition even after extended periods
in solution. Indeed many of the reactions of these phosphines
may be carried out in aqueous solution. The materials with P–Cl
bonds were, however, as expected moisture sensitive and their
reactions have not yet been investigated to the same extent.
coupling.
The infrared spectra of neat samples of the perfluorovinyl-
phosphines are dominated by four strong absorptions. The C᎐C
᎐
absorption is observed around 1710–1750 cmϪ1 and is typical of
systems in which the carbon–carbon double bond is substituted
428
J. Chem. Soc., Dalton Trans., 1999, 427–434

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Table 1 Characterising data
Analysis (%)
δ(19F) (J/Hz)a
Compound
C
H
P
F
Cl
—
—
δ(31P) (J/Hz)a
Fa
Fb
Fc
PPh2(CF᎐CF2)
63.8
(63.2)
44.8
4.1
(3.8)
2.1
11.5
21.1
Ϫ26.2 (dt)
(10, 61)
Ϫ84.3 (ddd)
(10, 30, 46)
Ϫ83.6 (ddd)
(12, 29, 42)
Ϫ82.1 (ddd)
(12, 35, 43)
Ϫ81.2 (ddd)
(9, 32, 48)
Ϫ107.6 (ddd) Ϫ178.6 (ddd)
(46, 61, 125) (11, 30, 125)
Ϫ106.1 (ddd) Ϫ176.5 (ddd)
(42, 57, 120) (12, 29, 120)
Ϫ105.9 (ddd) Ϫ175.5 (ddd)
(43, 57, 121) (12, 35, 121)
Ϫ103.9 (ddd) Ϫ181.2 (ddd)
(48, 54, 121) (5, 32, 121)
Ϫ103.7 (ddd) Ϫ186.4 (ddd)
᎐
(11.7) (21.4)
11.0 41.9
(11.5) (42.2)
PPh(CF᎐CF2)2
Ϫ51.5 (ttt)
(12, 12, 57)
Ϫ76.5 (m)
(12, 12, 57)
Ϫ59.5 (ttt)
(5, 9, 54)
Ϫ40.8 (ddd)
(7, 17, 84)
4.2 (m)
᎐
(44.4)
(1.9)
b
P(CF᎐CF2)3
᎐
P(CF᎐CF2)2Cl
15.1
(15.5)
13.3
(13.1)
27.8
(27.1)
34.0
(33.7)
24.0
(23.9)
45.0
(45.4)
35.9
—
—
13.5
49.5
15.1
᎐
(13.6) (49.9) (15.5)
16.6 30.8 38.3
(16.9) (31.1) (38.8)
9.7
(10.0) (18.4)
6.1 11.2
(6.2) (11.4)
6.1 22.2
(6.2) (22.7)
6.3
(6.2)
—
P(CF᎐CF2)Cl2
Ϫ82.9 (ddd)
(7, 32, 39)
Ϫ80.8 (m)
᎐
(39, 84, 123)
Ϫ94.0 (m)
(17, 32, 123)
Ϫ173.5 (m)
2 cis-[PtCl2{PPh2(CF᎐CF2)}2]
1.7
(1.6)
2.2
(2.0)
1.2
(1.0)
1.8
(2.0)
1.2
18.1
—
—
—
—
—
᎐
J(Pt–P) = 3698
12.4 (m)
3a [{AuCl[PPh2(CF᎐CF2)]}2]
Ϫ78.1 (m)
Ϫ76.0 (m)
Ϫ95.8 (m)
Ϫ95.8 (m)
Ϫ179.9 (m)
Ϫ180.5 (m)
᎐
3b [AuCl{PPh(CF᎐CF2)2}]
Ϫ7.8 (m)
᎐
4a [Mo(CO)5{PPh2(CF᎐CF2)}]
30.8 (d)
J(P–Fc) = 56
21.1 (t)
Ϫ82.5 (dd)
(32, 43)
Ϫ80.0 (dd)
(32, 40)
Ϫ98.2 (dd)
(43, 118)
Ϫ97.6 (dd)
(40, 116)
Ϫ170.6 (ddd)
(32, 56, 118)
Ϫ173.6 (ddd)
(32, 64, 116)
᎐
4b [Mo(CO)5{PPh(CF᎐CF2)2}]
24.0
(22.5)
᎐
(35.6)
(1.0)
J(P–Fc) = 64
a The multiplicity of signals is denoted by d = doublet, t = triplet, m = multiplet, etc.; |J(FF)| and |J(PF)| values are quoted but their assignment is not
explicitly given in most cases. b The high volatility of this compound precluded satisfactory elemental analysis. Mass spectrometric analysis gave m/z
(Mϩ) as 274.
Table 2 Selected bond lengths (Å) and angles (Њ) for PPh(CF᎐CF2)2
᎐
P(1)–C(1A)
P(1)–C(1B)
P(1)–C(1)
1.809(3)
1.807(3)
1.830(3)
1.318(4)
C(1A)–F(1A)
C(2A)–F(2A)
C(2A)–F(3A)
1.353(3)
1.321(4)
1.310(4)
C(1A)–C(2A)
C(1B)–P(1)–C(1A)
C(1B)–P(1)–C(1)
C(1A)–P(1)–C(1)
P(1)–C(1A)–C(2A)
98.45(14)
100.93(14)
100.26(13)
123.5(3)
P(1)–C(1A)–F(1A)
C(1A)–C(2A)–F(2A)
C(1A)–C(2A)–F(3A)
120.6(2)
124.2(3)
124.9(3)
liminary density functional calculations on a related per-
fluorovinyl compound23 suggest that the α-carbon atom is
appreciably more positively charged than the β-carbon which
would result in a stronger ionic contribution to the Cβ–F bonds
than in the Cα–F one. Atomic overlap population calculations
also suggest that there are more electrons involved in bonding
within the Cβ–F bonds than in the Cα–F linkage. Calculation
of the cone angle of this phosphine according to Tolman’s
method,24 based on our structural data, yields a value of
ca. 172Њ. This, however, is likely to be an upper limit since on
co-ordination the C–P–C angle usually decreases and the
substituents rearrange or intermesh to minimise their steric
requirements.1
Despite the fact that a few examples of Group 15 perfluoro-
vinyl derivatives have been prepared before, they do not appear
to have been isolated in sufficient quantities for their co-
ordination chemistry to be investigated. We have, therefore,
carried out reactions with these perfluorovinyl phosphines in
order to generate some typical late-transition metal complexes.
Fig. 2 Molecular structure of compound PPh(CF᎐CF2)2 showing the
atom labelling scheme adopted. Thermal ellipsoids are drawn at the
30% probability level and hydrogen atoms are omitted for clarity.
᎐
with strongly electron-withdrawing groups.21 The three C᎐F
stretching modes are observed as intense absorptions at ca.
1350, 1150 and 1050 cmϪ1.
To date no structural data have been reported for any
inorganic perfluorovinyl compound. Attempts were made to
grow crystals of these phosphines by freezing them in sealed
glass capillaries in a stream of cold nitrogen. Unfortunately
most of the materials resulted in glassy solids, but for PPh-
(CF᎐CF ) it was possible to obtain crystals suitable for X-ray
᎐
2
2
diffraction studies. The asymmetric unit contains two unique
molecules both of which show the expected pyramidal geom-
etry around the phosphorus atom and typical P᎐C and C᎐C
᎐
bond lengths,22 Fig. 2. As anticipated the P᎐C bond lengths to
the more electronegative perfluorovinyl groups are shorter than
that between the phosphorus and phenyl carbon. There do not
appear to be any particularly significant differences between
like distances and angles of the two different molecules within
the symmetric unit. There is, however, some variation in the
C᎐F bond lengths of the perfluorovinyl moiety [for example,
1.353(3), 1.321(4) and 1.310(4) Å; Table 2], although there
appear to be no especially significant intermolecular inter-
actions to account for these. The longest C᎐F distance is the
unique α-C᎐F bond which we note is consistent with that found
in structural studies on perfluoroalkyl-bound moieties. Pre-
Unfortunately only reactions with PPh (CF᎐CF ) or PPh-
᎐
2
2
(CF᎐CF ) proved to be consistently successful; in most other
᎐
2
2
cases the phosphine was recovered after work-up. The reaction
of an excess of PPh (CF᎐CF ) with K PtCl in water over 1 d
᎐
2
2
2
4
results in the formation of a white precipitate of cis-[PtCl2-
{PPh (CF᎐CF )} ] 2. The phosphorus NMR spectrum of this
᎐
2
2
2
new complex in CDCl3 exhibits a single multiplet at δ ϩ4.2,
a shift to higher frequency of ca. 30 ppm compared with the
value of δ Ϫ26.2 for the ‘free’ ligand. Associated with the
multiplet are satellites due to coupling with the spin active 195Pt
nucleus [I = ¹, 33%, 1J(Pt–P) = 3698 Hz]. The magnitude of the
¯
²
Pt–P coupling constant is somewhat larger than that observed
J. Chem. Soc., Dalton Trans., 1999, 427–434 429

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Fig. 4 Molecular structure of compound 3a. Details as in Fig. 2.
Fig. 3 Molecular structure of compound 2. Details as in Fig. 2.
Table 3 Selected bond lengths (Å) and angles (Њ) for compound 2
than phosphine-containing platinum() dichloride complexes.
This is consistent with the large magnitude of the Pt–P coupling
constant noted previously. It has been suggested that there
Pt(1)–P(1)
Pt(1)–P(2)
Pt(1)–Cl(1)
Pt(1)–Cl(2)
P(1)–C(1)
P(1)–C(7)
2.234(3)
2.228(3)
2.315(3)
2.343(3)
1.811(10)
1.813(11)
P(1)–C(13)
C(13)–C(14)
C(13)–F(1)
C(14)–F(2)
C(14)–F(3)
1.792(12)
1.31(2)
1.354(14)
1.296(14)
1.315(14)
1
is an inverse relationship between the magnitude of J(Pt–P)
and the Pt–P distance; our complex also appears to fit this
correlation.24,25 The short Pt–P and Pt–Cl bond distances
observed from complex 2 are presumably a reflection of the
electronic properties of the ligand rather than any steric factors
(which would give rise to longer rather than shorter distances)
and as such is consistent with the behaviour expected when a
phosphine ligand contains electron-withdrawing substituents.29
P(1)–Pt(1)–P(2)
P(2)–Pt–Cl(1)
P(1)–Pt(1)–Cl(1)
P(2)–Pt–Cl(2)
95.25(10)
90.73(11)
174.00(10)
178.09(11)
86.59(10)
Cl(1)–Pt(1)–Cl(2)
Pt(1)–P(1)–C(1)
Pt(1)–P(1)–C(7)
Pt(1)–P(1)–C(13)
87.43(11)
122.4(4)
112.6(4)
110.4(4)
The reactions between phosphines PPh (CF᎐CF ) and
᎐
2
2
P(1)–Pt(1)–Cl(2)
PPh(CF᎐CF ) and sodium tetrachloroaurate() were also
᎐
2
2
investigated. Although these resulted in the formation of new
complexes the most successful preparative route involved
reaction of the phosphine with an intermediate thiodiethanol
complex30 rather than with the tetrachloroaurate. This is
not surprising since the direct reaction of the phosphine
with sodium tetrachloroaurate() requires an excess of the
phosphine to reduce the gold complex, in so doing resulting
in oxidation of the phosphine. In view of the air stability
of these phosphines such a reaction is not favourable. The
resulting monochloromonophosphine gold() complexes were
characterised by a combination of elemental analyses and
spectroscopic methods and these data are summarised in Table
1. Co-ordination of the phosphine is confirmed by a change
in the phosphorus chemical shift, which in both cases is around
in many other bis(phosphine)platinum dichloride complexes,
although less than that found in some analogous bis(phosphite)
complexes, e.g. cis-[PtCl2{P(OMe)3}2] 1J(Pt–P) = 3908 Hz.25 The
19F NMR spectrum of the co-ordinated phosphine shows
a small shift of ca. 5 ppm to higher frequency in the position
of each set of peaks. This represents the first reported example
of a perfluorovinyl-containing phosphine ligand bound to any
metal centre. The complex appeared to be quite stable with
no visual sign or spectroscopically detected decomposition
apparent over a number of weeks even when left in solution.
Recrystallisation of the complex from a mixed dichloro-
methane–hexane solvent system produced a number of colour-
less crystals suitable for analysis by single-crystal X-ray dif-
fraction, Fig. 3. The crystal packing consists of discrete neutral
molecules separated by the normal van der Waals contacts. The
complex displays a cis configuration of the phosphine ligands
and a slight distortion from planar co-ordination geometry,
Table 3. The Pt–P bond distances of 2.228(3) and 2.234(3) Å
[average 2.231(3) Å] are shorter than those found in most other
crystallographically characterised cis-platinum() dichloride
bis(phosphine) complexes.26 For example in cis-[PtCl2(PPh3)2]
the platinum–phosphorus bond lengths are 2.251(2) and
2.265(2) Å [average 2.258(2) Å] and in the related perprotio-
vinyl complex cis-[PtCl2{PPh(C2H3)2}2] they are 2.248(1) and
2.243(2) Å [average 2.246(2) Å].27 The Pt–Cl distances in com-
plex 2 [2.315(3) and 2.343(3), average 2.329(3) Å] are also short
by comparison with the range of distances found in related
phosphine systems. For comparison in cis-[PtCl2(PPh3)2] and
in cis-[PtCl2{PPh(C2H3)2}2] the Pt–Cl distances are 2.333(2)
and 2.355(2) [average 2.344(2) Å] and 2.354(1) and 2.368(2) Å
[average 2.361(2) Å] respectively.27 However, shorter platinum–
phosphorus distances are observed for cis-[PtCl2P2] complexes
when the phosphorus donor is a phosphite, e.g. cis-[PtCl2-
{P(OMe)3}2], d(Pt–P)av = 2.174(3) Å, or a phosphine possessing
P–F bonds such as PF2R (R = tBu, adamantyl or o-MeOC6H4)
or PF3.28 It would, therefore, appear that the distances observed
for complex 2 are more akin to those found in phosphite- rather
δ 40 (δ Ϫ26.2 for free phosphine PPh (CF᎐CF ) to δ ϩ12.4
᎐
2
2
for the complex 2a and δ Ϫ7.8 for [AuCl{PPh(CF᎐CF ) }]
᎐
2
2
compared with δ Ϫ51.5 for PPh(CF᎐CF ) ). The large shifts to
᎐
2
2
higher frequency for the 31P resonances on co-ordination are
accompanied by small shifts to higher frequency in the position
of the 19F NMR signals.
Although complexes of both (perfluorovinyl)diphenylphos-
phine and bis(perfluorovinyl)phenylphosphine were prepared
only those of the former yielded crystals suitable for structure
determination. Solution of the data, shown in Fig. 4, resulted in
a dimeric structure [{AuCl[PPh (CF᎐CF )]} ] for the complex
᎐
2
2
2
with a molecule of solvent (CH2Cl2) shared between two dimers
located at a special position within the unit cell. The dimer
consists of two mutually perpendicular and nearly linear Cl–
Au–P units [Cl(1)–Au(1)–Au(2)–P(2) 98.6(1), Cl(1)–Au(1)–P(1)
177.36(8) and Cl(2)–Au(2)–P(2) 177.65(8)Њ; Table 4] that are
connected by a short Au–Au bond distance of 3.1945(5) Å. The
vast majority of the structurally characterised bis-phosphine
gold halide complexes are monomeric, unless bidentate phos-
phine ligands are involved.26 The exceptions to this are found
in gold() complexes containing fairly small phosphines, e.g.
bis[(dimethylphenylphosphine)halogenogold()]31 [d(Au–Au) =
3.104(2)–3.230(2) Å, cone angle 122Њ] and bis[iodo(trimethyl-
phosphine)gold()]32 [d(Au–Au) = 3.168(1) Å, cone angle 99Њ].
In these complexes, and compound 3a, the Au–Au distances lie
430
J. Chem. Soc., Dalton Trans., 1999, 427–434

View Article Online
Table 4 Selected bond lengths (Å) and angles (Њ) for compound 3a
Table 5 Observed ν(CO) absorptions for selected Mo(CO)5L com-
plexes
Au(1)–P(1)
Au(2)–P(2)
Au(1)–Cl(1)
Au(2)–Cl(2)
Au(1)–Au(2)
P(1)–C(1)
2.216(2)
2.218(2)
2.288(2)
2.278(2)
3.1945(5)
1.801(8)
1.808(8)
1.799(9)
C(13)–C(14)
C(13)–F(1)
C(14)–F(2)
C(14)–F(3)
C(27)–C(28)
C(27)–F(4)
C(28)–F(5)
C(28)–F(6)
1.294(12)
1.336(9)
ν/cmϪ1
1.307(10)
1.306(10)
1.277(13)
1.351(10)
1.315(11)
1.333(12)
Phosphine, L
A1
E
A1
Ref.
PPh2(CF᎐CF2), complex 4a 2077
PPh(CF᎐CF2)2, complex 4b 2084
1956
1965
1937
1938
1938
1939
1945
1958
1979
1982
1985
1990
1989
1988
1947
1947
1947
1942
1959
1965
1981
1991
1999
2012
This work
This work
᎐
P(1)–C(7)
P(1)–C(13)
᎐
PMe3
PMe2Ph
PMePh2
PPh3
2070
2071
2071
2072
2078
2083
2087
2093
2095
2104
35
35
35
35
36
37
37
37
36
36
P(1)–Au(1)–Cl(1)
P(1)–Au(1)–Au(2) 104.87(5)
P(2)–Au(2)–Cl(2) 177.65(8)
Cl(1)–Au(1)–Au(2) 77.59(5)
Cl(2)–Au(2)–Au(1) 84.44(6)
Au(1)–P(1)–C(1)
177.36(8)
Au(1)–P(1)–C(7)
Au(1)–P(1)–C(13)
Cl(1)–Au(1)–Au(2)–Cl(2) 98.6(1)
P(1)–C(13)–C(14)
P(1)–C(13)–F(1)
F(2)–C(14)–F(3)
114.9(3)
112.7(3)
P(OEt)3
P(OPh)3
PI3
PBr3
PCl3
129.3(7)
115.3(6)
109.8(8)
115.6(3)
PF3
between that found in the Au2 molecule (2.47 Å) and twice the
gold van der Waals radius (3.60 Å).33 The Au–P distances for
complex 3a are 2.216(2) and 2.218(2) Å [average 2.217(2) Å]
which are considerably shorter than that observed in the
monomeric structure for [AuCl(PPh3)] [d(Au–P) = 2.235(3) Å],
which is typical of the average Au–P distance of 2.236 Å for all
such structures containing trialkyl- and triaryl-phosphines.26
However, the Au–P distances are not quite as short as those
found in phosphite and fluorophosphine complexes, such as
[AuCl{P(OPh)3}] [d(Au–P) = 2.192(5) Å] and in the air-
sensitive chloro[(2,5-dimethylphenyl)difluorophosphine]gold()
complex [d(Au–P) = 2.188(2) Å].34 The gold–chlorine distances
in complex 3a, 2.288(2) and 2.278(2) Å [average 2.282(2) Å],
are, in contrast, not significantly shorter than that observed in
chloro(triphenylphosphine)gold() [d(Au–Cl) = 2.279(3) Å]. In
fact there appears to be relatively little variation of the gold–
chloride distances in these types of complexes even when
phosphite and fluorophosphine ligands are present. For
example in chloro(triphenyl phosphite)gold() and chloro[(2,5-
dimethylphenyl)difluorophosphine]gold() the gold–chloride
distances are 2.273(5) and 2.281(3) Å respectively.34 Once again
there is some variation in the C–F distances of the perfluoro-
vinyl ligand in the co-ordinated phosphine and these follow a
similar trend to those observed in the other perfluorovinyl-
phosphine structures.
19F NMR spectrum which now consists of doublets of doublets
for the signals due to the Fa and Fb nuclei and a doublet of
doublets of doublets for nucleus Fc. Unfortunately attempts to
crystallise the oily products obtained from these reactions were
unsuccessful.
For the monosubstituted complexes, assuming local C4v
symmetry, three infrared-active carbonyl stretching modes are
anticipated of symmetry 2A1 ϩ E and the observed infrared
spectra are consistent with this expectation. The three observed
peaks differed quite significantly in intensity and half-width.
The most intense, and broadest, peak is assigned to the E mode,
in line with the assignments made in related systems.35–37 The
two A1 modes are therefore assigned to the two other weaker
and sharper absorptions.
The carbonyl stretching frequencies obtained from infrared
spectra for toluene solutions of complexes 4a and 4b are com-
pared with those obtained for other phosphine-substituted
complexes in Table 5. The position of the highest frequency
A1 vibrational mode is most often used as a measure of the
electronic properties of the ligand.10 As can be seen from the
data presented in Table 5 the typical position of this absorption
for alkyl and aryl phosphine-substituted molybdenum penta-
carbonyl complexes is within the range 2070 to 2075 cmϪ1.
For phosphites this increases to 2078–2085 cmϪ1 and is even
higher for PI3, PBr3, PCl3 and PF3 ligands. There is relatively
little data available for fluorocarbon phosphine ligands, but for
[Mo(CO)5{PPh(C2F5)2}] the highest A1 mode absorption is
observed at 2089 cmϪ1 10 and for PMe(CF3)2 2094 cmϪ1.38 The
carbonyl absorptions observed for complexes 4a and 4b at 2077
and 2084 cmϪ1 respectively lie in a rather similar position to
those found for the analogous phosphite-containing complexes.
This result is perhaps not unexpected in view of the distances
observed in the crystal structure of both the platinum() and
gold() complexes which are more consistent with those found
in related phosphite- rather than the phosphine-containing
analogues.
Although it did not prove possible to obtain structural data
for the non-co-ordinated monosubstituted perfluorovinyl-
phosphines from which cone angle estimates could be made the
structural data for the gold and platinum complexes allow an
estimate for this parameter to be made for phosphine PPh2-
(CF᎐CF ) as 135Њ.
᎐
2
In view of the short metal–phosphorus bond distances
observed for the crystallographically characterised complexes a
comparison of the electronic properties of these ligands with
other phosphorus donors was undertaken via the synthesis
of phosphine-substituted molybdenum carbonyl complexes.
Addition of a slight excess of ligand PPh (CF᎐CF ) or PPh-
᎐
2
2
(CF᎐CF ) to a refluxing toluene solution of [Mo(CO)6]
᎐
2
2
followed by separation via column chromatography resulted in
analytically pure [Mo(CO)5L] (4a and 4b) as lightly coloured,
oily materials which were characterised by elemental analysis,
IR and NMR spectroscopies. Reactions carried out with ligand
As has previously been observed for other fluorocarbon
phosphines there is strong preference for mono- over di- or tri-
substituted complexes.10 Although it was possible thermally to
substitute two carbonyl ligands when using a large excess of the
phosphine this did not proceed cleanly, instead resulting in a
mixture of mono- and di-substituted products. We were unable
to produce any trisubstituted complexes via this method.
In conclusion, alkylperfluorovinylphosphines may be
obtained in high yields and purity from the reaction of
CF3CH2F (HFC-134a) with 2 equivalents of LiBu at low
temperature followed by the addition of chlorophosphines.
These materials are non-malodorous, air- and moisture-stable
and extremely soluble in a wide range of organic solvents. An
investigation of the co-ordination chemistry of these ligands
suggests from single crystal data and from infrared vibrational
P(CF᎐CF ) did not result in complex formation, according
᎐
2
3
to IR data, and mixtures of products were obtained when
reactions with ligands P(CF᎐CF ) Cl and P(CF᎐CF )Cl were
᎐
᎐
2
2
2
2
undertaken.
On co-ordination of the phosphine to the metal centre a shift
(δ Ϫ26.2 to 30.8 and Ϫ51.5 to 21.1 respectively for 4a and 4b)
and a simplification of the 31P NMR signal is observed. For
example, the 31P NMR spectrum of PPh (CF᎐CF ) consists of
᎐
2
2
a doublet of triplets, Fig 1(a), which on co-ordination to yield
4a simplifies to a doublet due to a loss of the coupling to Fa and
Fb. These changes in 31P NMR parameters are reflected in the
J. Chem. Soc., Dalton Trans., 1999, 427–434
431

View Article Online
Table 6 Crystallographic data for compounds PPh(CF᎐CF2)2, 2 and 3a
᎐
PPh(CF᎐CF2)2
cis-[PtCl2{PPh2(CF᎐CF2)}2] 2
[{AuCl[PPh2(CF᎐CF2)]}2]ؒ0.5CH2Cl2 3a
᎐
᎐
᎐
Formula
M
C10H5F6P
270.11
C28H20Cl2F6P2Pt
798.37
C29.5H21Au2Cl3F6P2
1039.68
Crystal system
Space group
Monoclinic
P21/c
Monoclinic
P21/n
Monoclinic
C2/c
a/Å
b/Å
c/Å
7.486(2)
26.719(7)
10.717(3)
90.22(3)
2143.5(9)
8
1.674
0.312
0.40 × 0.27 × 0.27
8581 (2.72–25.00)
1072
11.083(3)
15.162(2)
16.668(3)
100.231(14)
2756.6(3)
4
1.924
5.459
0.35 × 0.30 × 0.02
4843 (1.83–25.02)
1536
20.1903(14)
9.8220(15)
31.974(4)
103.493(9)
6165.7(12)
8
2.240
9.926
0.35 × 0.35 × 0.25
5591 (2.07–24.99)
3880
β/Њ
U/Å3
Z
Dc/g cmϪ3
µ(Mo-Kα)/mmϪ1
Crystal size/mm
No. data collected (θ range/Њ)
F(000)
Maximum, minimum transmission
T/K
R1, wR2 [I > 2σ(I )]
R1 (all data)
—
120(2)
0.0419, 0.1048
0.0712
1.0, 0.79
146(2)
0.0467, 0.1157
0.0947
1.0, 0.83
203(2)
0.0373, 0.0768
0.0559
Maximum, minimum residual electron
0.347, Ϫ0.237
2.178, Ϫ1.425
1.336 and Ϫ1.126
density/e ÅϪ3
studies that they appear to possess electronic properties similar
to those of traditional phosphite ligands.
See http://www.rsc.org/suppdata/dt/1999/427/ for crystallo-
graphic files in .cif format.
Syntheses
Experimental
PPh (CF᎐CF ). To a 3-neck round-bottom flask equipped
All reactions were carried out under dinitrogen in flame-dried
glass. Diethyl ether and THF were dried over sodium wire for
ca. 1 d and subsequently refluxed over sodium–benzophenone
under a nitrogen atmosphere. The compounds CF3H2CF (ICI
Klea), LiBu (2.5 M in hexanes, Acros), PPh2Cl (Lancaster),
PPhCl2, PCl3 and [Mo(CO)6] (all Aldrich) were used as supplied
after verification of their purity by spectroscopic methods.
Fluorine, phosphorus and proton NMR spectra were recorded
on a Bruker AC200 spectrometer operating at 188.296, 81.83
and 200.13 MHz respectively. Peak positions are quoted rel-
ative to external CFCl3, 85% H3PO4 and SiMe4 using the high
frequency positive convention. Carbon NMR spectra were
recorded on a Bruker AC300 spectrometer operating at 75.47
MHz and referenced to external SiMe4. Infrared spectra were
recorded as Nujol mulls or of samples dissolved in a suitable
hydrocarbon solvent held between KBr on a Nicolet PC-5
FTIR spectrometer. Elemental analyses were performed by this
Department’s microanalytical service.
᎐
2
2
with magnetic stirrer, inlet and outlet for argon, and held in
an ethanol slush bath, was added precooled (Ϫ78 ЊC) diethyl
ether (200 cm3). The temperature of the flask and its contents
was lowered to ca. Ϫ100 ЊC and liquid HFC-134a (5.74 cm3,
0.068 mol) introduced. Two equivalents of LiBun (2.5 M in
hexane, 54.40 cm3, 0.136 mol) were added slowly over 15 min.
An internal thermocouple was used to ensure that during
addition the temperature of the solution remained below
Ϫ80 ЊC. After complete addition the temperature was raised
and maintained between Ϫ55 and Ϫ65 ЊC for 2 h. The reaction
mixture was then cooled to Ϫ90 ЊC and a concentrated cold
solution of chlorodiphenylphosphine (10.14 cm3, 0.068 mol
dissolved in 50 cm3 diethyl ether) added dropwise whilst main-
taining the solution temperature below Ϫ90 ЊC. The reaction
was left at Ϫ78 ЊC for 2 h after which it was allowed to attain
room temperature overnight. Addition of 100 cm3 of hexane
resulted in the precipitation of lithium salts which were
removed by filtration. The resulting organic phase was dried
over anhydrous MgSO4 overnight. Distillation of the crude
product under vacuum (112 ЊC, 10 mmHg) resulted in PPh2-
(CF᎐CF ) as a clear liquid. Yield 14.5 g, 80%. ν/cmϪ1 (neat)
X-Ray crystallography
Many of the details of the structure analyses carried out
᎐
2
on compounds PPh(CF᎐CF ) , 2 and 3a are summarised in
᎐
2
2
3045 (C–H), 1725 (C᎐C), 1300 (C–F), 1135 (C–F) and 1100
᎐
Table 6. Measurements for compounds 2 and 3a were made on
crystals prepared by slow solvent evaporation, on a Rigaku
AFC6S and Nonius MAC3 CAD4 diffractometer respectively.
(C–F). δ(13C) (CDCl ) 159 (1C, m, CF ᎐CF) and 131 (1C, m,
᎐
3
2
CF ᎐CF).
᎐
2
The crystal of PPh(CF᎐CF ) was grown at low temperature at
᎐
2
2
PPh(CF᎐CF ) . In an analogous method HFC-134a (9.40
᎐
2
2
the University of Edinburgh. A stable solid–liquid equilibrium
was established on a sample held in a glass capillary at 248 K.
Reduction of the temperature to 247.5 K overnight led to
steady crystal growth. Data for this compound were collected
on a Stoe Stadi-4 diffractometer equipped with an Oxford
cryosystems low temperature device. The data obtained from
the two heavy-atom complexes were corrected for Lorentz-
polarisation and absorption using the ψ-scan method. X-Ray
structural data solution was by direct methods and refined
against F 2 using SHELXTL39 or SHELXL9740 with H
atoms in ideal positions. All non-H atoms were modelled with
anisotropic displacement parameters. The asymmetric units
shown in the figures were produced using ORTEP 3 for
Windows.41
cm3, 55.90 mmol) was treated with LiBu (10 M, 22.36 cm3,
223.5 mmol) in 400 cm3 of diethyl ether at Ϫ78 ЊC. After ca. 2 h
the solution was cooled to Ϫ100 ЊC and a precooled solution
of PPhCl2 (7.60 cm3, 111.70 mmol) dissolved in diethyl ether
(50 cm3) slowly added. Work-up and distillation at 77 ЊC
resulted in 20.4 g, 67% of pure PPh(CF᎐CF ) . ν/cmϪ1 (neat)
᎐
2
2
3040 (C–H), 1740 (C᎐C), 1720 (C᎐C), 1315 (C–F), 1170 (C–F)
᎐
᎐
and 1050 (C–F). δ(13C) (CDCl ) 160 (1C, m, CF ᎐CF) and 127
᎐
2
3
(1C, m, CF ᎐CF).
᎐
2
P(CF᎐CF ) . In an analogous method HFC-134a (2.15 cm3,
᎐
2
3
25.48 mmol) was treated with LiBu (10 M, 5.01 cm3, 50.96
mmol) in 100 cm3 of diethyl ether at Ϫ78 ЊC. After ca. 2 h the
solution was cooled to Ϫ100 ЊC and a precooled solution of
CCDC reference number 186/1264.
432
J. Chem. Soc., Dalton Trans., 1999, 427–434

View Article Online
PCl3 (0.64 cm3, 7.28 mmol) dissolved in diethyl ether (5 cm3)
was refrigerated overnight resulting in a white powder which
very slowly added. Work-up and distillation at 54 ЊC resulted
was dried under vacuum. Yield 0.241 g, 48%.
in 0.48 g, 24% yield of pure P(CF᎐CF ) . m/z (GC-MS) 274
᎐
2
3
(Mϩ, 30%), 193 ([M Ϫ C2F3]ϩ, 100%) and 112 ([M Ϫ 2C2F3]ϩ,
[Mo(CO) {PPh (CF᎐CF )}] 4a. To a solution of molybdenum
᎐
5
2
2
hexacarbonyl (0.262 g, 0.99 mmol) in toluene (30 cm3) was
added perfluorovinyldiphenylphosphine (0.260 g, 0.98 mmol).
After refluxing under nitrogen for 2 h the reaction mixture was
filtered to yield an almost colourless solution. Removal of the
solvent under vacuum resulted in 0.28 g (56%) of an oily
material. ν/cmϪ1 (toluene) 2077 (CO), 1956 (CO), 1989 (CO),
65%).
P(CF᎐CF )Cl . In an analogous method to that described,
᎐
2
2
HFC-134a (2.15 cm3, 25.48 mmol) was treated with LiBu
(10 M, 5.01 cm3, 50.96 mmol) in 100 cm3 of diethyl ether at
Ϫ78 ЊC. After ca. 2 h the solution was cooled to Ϫ100 ЊC and
a precooled solution of PCl3 (0.64 cm3, 7.28 mmol) dissolved in
5 cm3 diethyl ether very slowly added. Work-up and distillation
1726 (C᎐C), 1310 (C–F), 1141 (C–F) and 1049 (C–F).
᎐
[Mo(CO) {PPh(CF᎐CF ) }] 4b. To a solution of molybdenum
᎐
5
2 2
at 70 ЊC resulted in 0.85 g (64% yield) of pure P(CF᎐CF )Cl .
᎐
2
2
hexacarbonyl (0.137 g, 0.52 mmol) in toluene (30 cm3)
was added bis(perfluorovinyl)phenylphosphine (0.139 g, 0.51
mmol). After refluxing under nitrogen for 3 h the reaction
mixture was passed down a column eluted with toluene to yield
a greeny yellow solution. Removal of the solvents under
vacuum resulted in 0.122 g (47% yield) of a dark oily material.
P(CF᎐CF ) Cl. In an analogous method HFC-134a (2.15
᎐
2
2
cm3, 25.48 mmol) was treated with LiBu (10 M, 5.01 cm3, 50.96
mmol) in 100 cm3 of diethyl ether at Ϫ78 ЊC. After ca. 2 h the
solution was cooled to Ϫ100 ЊC and a precooled solution of
PCl3 (0.64 cm3, 7.28 mmol) dissolved in 5 cm3 diethyl ether
very slowly added. Work-up and distillation at 54 ЊC resulted in
ν/cmϪ1 (toluene) 2084 (CO), 1965 (CO), 1988 (CO), 1719 (C᎐C),
᎐
0.80 g (48% yield) of pure P(CF᎐CF ) Cl. ν/cmϪ1 (neat) 1730
1313 (C–F), 1159 (C–F) and 1049 (C–F).
᎐
2
2
(C᎐C), 1320 (C–F), 1160 (C–F) and 1035 (C–F). δ(13C) (CDCl )
᎐
3
159 (1C, m, CF ᎐CF) and 126 (1C, m, CF ᎐CF).
᎐
᎐
2
2
Acknowledgements
We thank ICI Klea for providing samples of HFC-134a,
Johnson Matthey for the loan of precious metal complexes
and UMIST for financial support. We acknowledge the use of
the EPSRC’s Chemical Database Service at Daresbury.
cis-[PtCl {PPh (CF᎐CF )} ] 2. To a solution of potassium
᎐
2
2
2
2
tetrachloroplatinate() (1.0 g, 2.41 mmol) in water (50 cm3) was
added (perfluorovinyl)diphenylphosphine (1.14 g, 4.3 mmol)
and stirred overnight. A mixture of a pink-tan and white pre-
cipitate was formed. The mixture was heated on a steam-bath
until the pink precipitate dissolved, and a layer of white solid
formed. The solid was filtered off, washed with water, crushed
in a mortar and dried under vacuum. The dried solid was then
suspended in 10 cm3 of pentane containing 2 drops of PPh-
(CF᎐CF ) and stirred for ca. 15 min to ensure that any trans
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Pergamon, Oxford, 1977.
᎐
2
isomer that may have formed isomerises to the less soluble cis
form. The mixture was then filtered, and the white solid dried
under vacuum to remove the excess of phosphine. Yield 0.70 g,
36%.
[{AuCl[PPh (CF᎐CF )]} ] 3a. Sodium tetrachloroaurate()
᎐
2
2
2
dihydrate (0.394 g, 1 mmol) dissolved in water (20 cm3) was
added dropwise over 30 min to a stirred solution of thiodi-
ethanol (0.367 g, 3 mmol) held at 0 ЊC. A yellow precipitate was
formed initially which redissolved on stirring. Eventually the
yellow colour of the mixture was discharged. A solution of the
PPh (CF᎐CF ) (0.266 g, 1 mmol dissolved in 40 cm3 of chloro-
᎐
2
2
form) was then added dropwise over 45 min with stirring. The
resulting colourless mixture was stirred for 1 h during which
time it was allowed to warm to room temperature. The chloro-
form layer was then separated and the remaining aqueous
phase extracted with 20 cm3 of chloroform. The organic layers
were combined before being removed by rotary evaporator to
leave behind a white solid. The product was refrigerated over-
night to allow for further precipitation. A white powder was
recovered and dried under vacuum. Yield 0.304 g, 61%.
[AuCl{PPh(CF᎐CF ) }] 3b. Using a similar method to that
᎐
2
2
described for the synthesis of complex 3a, sodium tetrachloro-
aurate() dihydrate (0.394 g, 1 mmol) dissolved in water (20
cm3) was added dropwise over 30 min to a stirred solution of
thiodiethanol (0.367 g, 3 mmol) held at 0 ЊC. A yellow precipi-
tate was formed initially which redissolved on stirring. A
solution of PPh(CF᎐CF ) (0.270 g, 1 mmol dissolved in
᎐
2
2
40 cm3 of chloroform) was then added dropwise over 45 min
with stirring. The resulting colourless mixture was stirred for
1 h during which time it was allowed to warm to room tem-
perature. The chloroform layer was separated and the remain-
ing aqueous phase extracted with 20 cm3 of chloroform. The
organic layers were combined and the solvents removed on a
rotary evaporator to leave behind a white solid. The product
21 K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds. Part B: Applications in coordination,
J. Chem. Soc., Dalton Trans., 1999, 427–434
433

View Article Online
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J. Chem. Soc., Dalton Trans., 1999, 427–434