Platinum(II) halide complexes of PPh2(CF=CF2) and PPh2(CCl=CF2). The synthesis and crystal structure of [PtI(μ-I){PPh2(CX=CF2)}]2, (X = F, Cl); The first crystallographically characterised iodide-bridged platinum(II) phosphine dimers

Article abstract of DOI:10.1016/j.ica.2005.02.012

The reactions of the fluorovinyl-substituted phosphines PPh ₂(CF=CF₂) and PPh₂(CCl=CF₂), with K₂PtX₄ (X = Br, I) have been investigated. The resulting complexes have been characterized by a combination of ¹⁹F and ³¹P{¹H} NMR, IR and Raman spectroscopy. The reactions of these phosphines with K₂PtBr₄ yield the monomeric complexes cis-[PtBr₂{PPh₂(CF=CF₂)}₂] (1) and trans-[PtBr₂{PPh₂(CCl=CF₂)} ₂] (2), respectively, whilst the reactions with K₂PtI ₄ yield both the monomeric species trans-[PtI₂{PPh ₂(CX=CF₂)}₂], {X = F (3), Cl (4)}, and the dimeric species [PtI(μ-I){PPh₂(CX=CF₂)}]₂, {X = F (5), Cl (6)}. The dimers 5 and 6 represent the first crystallographically characterised platinum(II) iodide-bridged phosphine complexes, and both adopt the symmetric-trans structure.

Full text of DOI:10.1016/j.ica.2005.02.012

Inorganica Chimica Acta 358 (2005) 2543–2548
www.elsevier.com/locate/ica
Platinum(II) halide complexes of PPh2(CF@CF2) and
PPh2(CCl@CF2). The synthesis and crystal structure of
[PtI(l-I){PPh2(CX@CF2)}]2, (X = F, Cl); the first crystallographically
characterised iodide-bridged platinum(II) phosphine dimers
*
Nicholas A. Barnes, Alan K. Brisdon , Joseph G. Fay, Robin G. Pritchard,
John E. Warren
School of Chemistry, The University of Manchester, Faraday Building, Campus North, Manchester M60 1QD, UK
Received 17 January 2005; accepted 6 February 2005
Available online 16 March 2005
Abstract
The reactions of the fluorovinyl-substituted phosphines PPh2(CF@CF2) and PPh2(CCl@CF2), with K2PtX4 (X = Br, I) have been
investigated. The resulting complexes have been characterized by a combination of 19F and 31P{1H} NMR, IR and Raman spec-
troscopy. The reactions of these phosphines with K2PtBr4 yield the monomeric complexes cis-[PtBr2{PPh2(CF@CF2)}2] (1) and
trans-[PtBr2{PPh2(CCl@CF2)}2] (2), respectively, whilst the reactions with K2PtI4 yield both the monomeric species trans-
[PtI2{PPh2(CX@CF2)}2], {X = F (3), Cl (4)}, and the dimeric species [PtI(l-I){PPh2(CX@CF2)}]2, {X = F (5), Cl (6)}. The dimers
5 and 6 represent the first crystallographically characterised platinum(II) iodide-bridged phosphine complexes, and both adopt the
symmetric-trans structure.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Fluorovinyl; Chlorodifluorovinyl; Phosphines; Platinum complexes; Crystal structures
1. Introduction
gands, L, when cleavage of the halide bridges occur.
These dimers are usually obtained by boiling mono-
meric [PtX2(PR3)2] complexes with PtX2 in high boil-
ing hydrocarbons such as xylene or napthalene [3],
but may also be prepared in one-step by refluxing ter-
tiary phosphines with PtCl2 in p-chlorotoluene [4].
More recently, the reaction of ZeiseÕs dimer, [PtCl(l-
Cl)(g2-C2H4)]2, with two equivalents of tertiary phos-
phine in boiling toluene, or tetrachloroethane, has
been used to synthesise a series of chloride-bridged di-
mers of the type [PtCl(l-Cl)(PR3)]2 [5]. Finally, com-
plexes with bulky phosphines, such as PCy3, have
been prepared by the slow addition of very dilute solu-
tions of the phosphine to K[PtCl3(C2H4)] under anaer-
obic conditions [6].
Monomeric platinum(II) halide complexes contain-
ing tertiary phosphine ligands, [PtX2(PR3)2] (X = ha-
lide), are ubiquitous in coordination chemistry, and
generally adopt either a cis- or trans-square-planar
geometry. A more limited number of dimeric com-
plexes with bridging halide ligands of formula
[PtX(l-X)(PR3)]2 are also known [1,2]. Such complexes
provide useful precursors to monomeric complexes of
the type [PtX2(PR3)L], through their reactions with li-
*
Corresponding author. Tel.: +0161 306 4459; fax: +0161 306 4557.
E-mail address: alan.brisdon@manchester.ac.uk (A.K. Brisdon).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.02.012

2544
N.A. Barnes et al. / Inorganica Chimica Acta 358 (2005) 2543–2548
These dimers may adopt one of three possible geom-
isomer [1J(PtP) = 3728 Hz] was also detected in
NMR studies (trans:cis ratio 80:20). More detailed
studies have now revealed that solutions of trans-
[PtCl2{PPh2(CCl@CF2)}2] left for several days isome-
rise completely to the cis-isomer, suggesting that this
is the thermodynamic product of the reaction. For
[PtCl2{PPh2(CF@CF2)}2] it is likely that the observa-
tion of only the cis-isomer is a result of the isomerisa-
tion occuring more rapidly, probably as a result of the
smaller size of PPh2(CF@CF2) compared with
PPh2(CCl@CF2) and the difference in their donor
properties. The geometries of both cis-[PtCl2{PPh2
(CF@CF2)}2] and trans-[PtCl2{PPh2(CCl@CF2)}2]
have been confirmed by single-crystal X-ray diffraction
[15,16]. Here, we report the outcome of a study on the
reactions of PPh2(CF@CF2) and PPh2(CCl@CF2) with
K2PtBr4 and K2PtI4.
etries, as shown below, symmetric-trans (i), symmetric-
cis (ii), or asymmetric (iii) isomeric forms. To date the
only crystallographically characterised [PtX(l-X)
(PR3)2]2 complexes are limited to chloride-bridged di-
mers of the type [PtCl(l-Cl)L2]2, where L = PMe3 [7],
PEt3 [8], PPr3 [9], and PBut2cycloC3H5 [10], and all of
these complexes have been shown to adopt the symmet-
ric-trans structure (i).
I
I
I
L
I
I
I
I
I
I
I
I
I
L
L
Pt
Pt
Pt
Pt
Pt
Pt
L
L
L
(i)
(iii)
(ii)
Where solid-state structures are not available the
existence of the halide-bridged dimers has been in-
ferred from 31P{1H} NMR studies [5,11]. These have
shown that although [PtX(l-X)(PR3)]2 dimers give
similar 31P chemical shift values to the monomeric
complexes, they may be distinguished by the Pt–P
coupling constants, which are usually significantly lar-
2.1. Reaction of PPh2(CX@CF2) [X = F, Cl] with
K2PtBr4 and K2PtI4
When two equivalents of PPh2(CF@CF2) are added
to K2PtBr4 in an ethanol/water solvent system a white
solid 1 rapidly precipitates. The 31P{1H} NMR spec-
trum of the solid dissolved in CDCl3 displays a doublet
[2J(PFa) = 39 Hz] at +2.6 ppm with attendant platinum
satellites [1J(PtP) = 3625 Hz], which, on the basis of
the magnitude of the coupling, is assigned to the cis-
isomer. This was further confirmed by the Raman spec-
trum of 1 which displays two m(Pt–Br) bands at 227 and
189 cmÀ1, consistent with a cis-[PtX2L2] system of idea-
lised C2v symmetry. A weak signal observed at +8.9 ppm
in the 31P{1H} NMR spectrum is assigned to the trans-
isomer. Although no platinum satellites could be re-
solved this assignment was made on the basis that the
resonance appears as a triplet, due to virtual coupling
with an apparent 1/2|2J(PF) + 4J(PF)| coupling of
18 Hz. Such virtual coupling is typical for a trans-
arrangement of phosphine ligands, and we have ob-
served it frequently for a large number of trans-square
planar complexes of perfluorovinyl substituted phos-
phines, where the only J(PF) coupling observed is to
the a-fluorine atom [16,17]. The detection of both iso-
mers of [PtBr2{PPh2(CF@CF2)}2] offers additional evi-
dence that the platinum halide complexes of
PPh2(CF@CF2) undergo a trans–cis isomerisation, as
observed for [PtCl2{PPh2(CCl@CF2)}2], but more rap-
idly. In contrast the reaction of PPh2(CCl@CF2) with
K2PtBr4 yields a yellow solid 2, the 31P{1H} NMR spec-
trum of which shows a singlet at +18.4 ppm, with plat-
inum satellites [1J(PtP) = 2715 Hz] and on this basis is
assigned as trans-[PtBr2{PPh2(CCl@CF2)}2]. The Ra-
man spectrum of 2 displays only one m(Pt–Br) stretch
at 206 cmÀ1, as expected for a trans-[PtX2L2] system of
idealised D2h symmetry. No resonances assignable to
the cis-isomer are observed, and it would appear that
1
ger. The magnitude of the J(PtP) coupling constants
for sym-trans chloride-bridged dimers (i) are observed
in the range 3800–4100 Hz [5,12]. This is significantly
larger than those found for the monomeric complexes,
where typical values are: cis (3300–3700 Hz) and trans
(2300–2600 Hz)[13]. For the sym-cis isomers (ii)
1J(PtP) values lie between those of the cis- and
trans-monomeric complexes, 2800–3100 Hz [1]. It
may also be possible to identify dimeric complexes
3
4
by the presence of additional J(PtP) and J(PP) cou-
plings, but these are not always observed and they are
typically small, particularly the latter, which are fre-
quently less than 5 Hz [5]. Analysis of NMR data
has shown that the sym-trans isomer, (i), is preferred
in the majority of cases, although a small number of
examples of the sym-cis isomer (ii) are known
[1,5,14]. There are no data available for complexes
of the asymmetric arrangement shown in (iii).
2. Results and discussion
We have been investigating the coordination chem-
istry of perfluorovinyl-substituted phosphines, and
have reported that the reaction of K2PtCl4 with
PPh2(CF@CF2) yields the monomeric complex cis-
[PtCl2{PPh2(CF@CF2)}2] [15], which was assigned in-
1
tially on the basis of a J(PtP) coupling constant value
of 3698 Hz. In contrast, the analogous 1-chloro-2,2-
difluorovinyl-containing phosphine PPh2(CCl@CF2)
yields, initially, the trans-isomer of [PtCl2{PPh2(CCl@
CF2)}2], 1J(PtP) = 2794 Hz, [16] although the cis-

N.A. Barnes et al. / Inorganica Chimica Acta 358 (2005) 2543–2548
2545
the steric threshold has been reached, whereby isomeri-
sation to the cis-isomer is no longer favoured.
The reactions of K2PtI4 with both PPh2(CF@CF2)
and PPh2(CCl@CF2) yield orange solids 3 and 4, which
are again assigned as trans-isomers on the basis of
1J(PtP) coupling magnitudes of 2653 and 2647 Hz
respectivly, and the presence of only one m(Pt–I) stretch
in the Raman spectrum (at 152 and 148 cmÀ1, respec-
tively). Once again, no cis-isomers were observed, how-
ever both reactions also yielded red-coloured filtrates
from which, by extraction with chloroform, the deep-
red solids, 5 and 6 were isolated. These complexes exhi-
bit a doublet in the 31P{1H} NMR spectrum at
À2.2 ppm, 1J(Pt–P) = 3818 Hz for 5, and a singlet at
Fig. 1. A representation of the molecular structure of [PtI(l-
I){PPh2(CF@CF2)}]2 (5). Thermal ellipsoids are shown at the 30%
probability level and hydrogen atoms have been removed for clarity.
1
+9.8 ppm, J(Pt–P) = 3873 Hz for 6. These values are
1
not indicative of the cis-isomer, since the J(PtP) cou-
pling is too large, and are more typical of that observed
for halide-bridged dimeric platinum(II) complexes; for
example the 1J(PtP) coupling constants for chloride-
bridged platinum(II) dimers containing PMe3 and
PPh3 are 3853 and 4097 Hz, respectively [5]. The Raman
data collected for 5 was of poor quality due to fluores-
cence and decomposition of the sample in the laser
beam, and no useful data was obtained. However, the
Raman spectrum of 6 displays two Pt–I modes at 137
and 168 cmÀ1, and on the basis of previously reported
observations [18] these are likely to be the bridging
m(Pt–I) trans to the terminal iodine (137 cmÀ1), and trans
to phosphorus (168 cmÀ1). The terminal m(Pt–I) stretch-
ing mode in [PtI(l-I)(PR3)]2 (where R = Me, Et) has
been reported to be very weak [18], and we could not
confidently assign it for 6.
Fig. 2. A representation of the molecular structure of [PtI(l-
I){PPh2(CCl@CF2)}]2 (6). Thermal ellipsoid probabilities are shown
at the 30% probability level and hydrogen atoms have been removed
for clarity.
2.2. Crystal structures of [PtI(l-I){PPh2(CF@CF2)}]2
(5) and [PtI(l-I){PPh2(CCl@CF2)}]2 (6)
Recrystallisation of complexes 5 and 6 by slow evap-
oration of a dichloromethane:hexane layered solution,
resulted in crystals suitable for analysis by X-ray diffrac-
tion studies. In both cases the complexes crystallise in
the monoclinic space group P21/n (no. 14). Solution of
the data for complexes 5 and 6 confirms the presence
of dimeric species. In both cases the molecules possess
a centre of symmetry, giving rise to symmetrical-trans io-
dide-bridged dimeric structures as suggested by the spec-
troscopic data. The molecular structures of 5 and 6 are
shown in Figs. 1 and 2, respectively, and selected bond
lengths and angles are given in Table 1.
These two structures represent the first iodide-
bridged platinum(II) phosphine dimers to be crystallo-
graphically characterised according to searches of the
CCDC X-ray database. The platinum centres exhibit
distorted square-planar arrangements, with I(1)–Pt(1)–
I(2) and P(1)–Pt(1)–I(1#1) angles of 171.67(5)ꢁ and
175.29(12)ꢁ, respectively for 5, and 171.58(4)ꢁ and
177.99(8)ꢁ for 6. The iodide-bridges in both 5 and 6
Table 1
˚
Selected bond lengths (A) and angles (ꢁ) for complexes 5 and 6
5
6
Pt–P(1)
Pt–I(1)
2.224(5)
2.228(3)
2.6100(14)
2.6463(14)
2.6021(15)
1.85(2)
2.5901(15)
2.6427(14)
2.5882(15)
1.820(12)
1.797(10)
1.801(11)
1.298(16)
1.697(11) X = Cl(1)
1.308(13)
1.321(13)
171.58(3)
93.63(8)
Pt–I(#1)
Pt–I(2)
P(1)–C(1)
P(1)–C(3)
P(1)–C(9)
1.778(18)
1.814(19)
1.27(3)
C(1)–C(2)
C(1)–X gem
C(2)–F(2) trans
C(2)–F(3) cis
I(1)–Pt–I(2)
P(1)–Pt–I(1)
P(1)–Pt–I(#1)
P(1)–Pt–I(2)
I(1)–Pt–I(#1)
I(2)–Pt–I(#1)
Pt–I(1)–Pt
1.34(3) X = F(1)
1.30(3)
1.31(3)
171.67(5)
95.95(12)
175.29(12)
91.44(13)
84.17(4)
178.00(8)
92.90(8)
84.38(3)
88.77(5)
95.83(4)
89.10(3)
95.62(3)

2546
N.A. Barnes et al. / Inorganica Chimica Acta 358 (2005) 2543–2548
Fig. 3. A view of the extended structure of [PtI(l-I)PPh2(CF@CF2)]2 5, showing short FÁ Á ÁF interaction.
show slight asymmetry. In 5 the Pt–I distance trans to
mation. The series of platinum halide complexes of both
PPh2(CF@CF2) and PPh2(CCl@CF2) have shown a
strong tendency to undergo a trans–cis isomerisation,
except where the halide ligand is too bulky to accommo-
date a cis-arrangement. This is particularly true for the
iodide complexes, where we observe the formation of di-
meric complexes as the thermodynamic products of the
reaction as cis-monomeric complexes are unlikely based
upon steric arguments.
˚
the phosphine [2.6463(14) A] is longer than that for
the Pt–I bond trans to the terminal iodide
˚
[2.6100(14) A]. Both of these distances are longer than
˚
the terminal Pt–I distance of 2.6021(15) A. The same
trend in Pt–I bond lengths is observed for complex 6,
˚
both the terminal Pt–I [2.5882(15) A] and bridged Pt–I
˚
trans to iodine [2.5901(15) A] are somewhat shorter than
the corresponding distances observed for 5. The relative
Pt–I bond lengths for the central Pt2I2 unit are in agree-
ment with that expected on the basis of the relative
trans-influence of the iodide and phosphine ligands,
and are consistent with the data for related platinum(II)
iodide-bridged dimers such as [PtI(l-I)(CO)]2 [19],
[PtI(l-I)(NHEt2)]2 [20], and [PtI(l-I)(R2SO)]2 (R = nPr)
[21], (although in the benzyl-substituted sulfoxide dimer
the terminal Pt–I bond is slightly longer than the
bridged Pt–I trans to iodine [21]). In both complexes
the Pt2I2 subunits display smaller I–Pt–I angles
[84.17(4)ꢁ 5, 84.37(4)ꢁ 6] than Pt–I–Pt angles [95.83(4)ꢁ
5, 95.63(4)ꢁ 6]. Inspection of the extended structures of
5 and 6 reveal no particularly close interactions, but
congregation of the perfluorovinyl groups is observed
for 5, resulting in the formation of fluorous and hydro-
carbon domains within the crystal (Fig. 3). A short fluo-
rine-fluorine contact is observed between two fluorine
atoms trans to phosphorus of neighbouring molecules,
In conclusion, complexes 5 and 6 represent the first
examples of a rational synthesis that produces plati-
num(II) iodide-bridged phosphine dimers. These have
been structurally characterised, and they should provide
precursors for the generation of new mixed ligand
systems.
3. Experimental
3.1. General experimental
Potassium tetrachloroplatinate (Johnson Matthey)
was used as supplied, and K2PtX4 salts (X = Br, I) were
prepared by the reaction of aqueous solutions of
K2PtCl4 with an excess of aqueous KBr/HBr or KI,
respectively, and used in situ. PPh2(CF@CF2) [15] and
PPh2(CCl@CF2) [16] were synthesised as described pre-
viously from CF3CH2F or CF3CH2Cl (Ineos-Fluor),
nBuLi (2.5 M in hexanes, Acros) and PPh2Cl (Lancas-
ter). All commercially supplied materials were used
without further purification. Fluorine and phosphorus
NMR spectra were recorded on a Bruker DPX200
instrument operating at 188.310 and 81.014 MHz,
respectively. The samples were dissolved in CDCl3 and
peak positions are quoted relative to CFCl3 and 85%
H3PO4 using the high frequency positive convention. In-
fra-red and Raman spectra were recorded on a Nicolet-
Nexus combined FT-IR/FT-Raman spectrometer with
˚
[F(2) Á Á Á F(2) = 2.83(2) A, c.f. sum of the Van der Waals
˚
radii of 2.94 A]. In contrast no such close approach of
the chloro-difluorovinyl units is observed in the ex-
tended structure of 6.
The formation of dimers with fluorinated phosphine
ligands is not unprecedented, for example, [PtCl(l-
Cl){PPh2(CF3)}]2 [22] and [PtCl(l-Cl){PPh(C2F5)2}]2
[23] are known; however the production of 5 and 6 from
the reactions of K2PtI4 and PPh2(CX@CF2) (X = F, Cl)
under such mild conditions is surprising since such di-
mers usually require elevated temperatures for their for-

N.A. Barnes et al. / Inorganica Chimica Acta 358 (2005) 2543–2548
2547
Table 2
Crystallographic data for 5 and 6
tion was stirred at room temperature for 20 min. The
resulting precipitate was filtered, washed with water,
then ethanol and dried in vacuo for 1 h. The product
was isolated as a white solid, m.p. 170–172 ꢁC,
Yield = 69%. Calc. for C28H20F6P2Br2Pt: C, 37.9; H,
2.3; Br, 18.0. Found C, 38.2; H, 2.0; Br, 18.1%.
31P{1H} NMR: d: +2.6 [d, J(PF) = 39 Hz, J(PtP) =
3625 Hz]. 19F NMR: d: À81.6 (trans) [dd,
2J(FF) = 35 Hz, 3J(FF) = 31 Hz, 4J(PtF) = 22 Hz],
À93.9 (cis) [dd, 2J(FF) = 35 Hz, 3J(FF) = 117 Hz,
4J(PtF) = 21 Hz], À172.6 (gem) [ddd, 3J(PF) = 39 Hz,
3J(FF) = 31 Hz,3 J(FF) = 117 Hz, 3J(PtF) = 72 Hz]. Ra-
man (cmÀ1): 227, 189 [m(Pt–Br)]. IR (nujol, cmÀ1): 1730
[C@C], 1308, 1154, 1053 [C–F].
5
6
Empirical formula
Fw
C28H20F6I4P2Pt2
1430.14
red, plate
C28H20Cl2F4I4P2Pt2
1463.06
red, prism
Color, habit
Crystal system
Space group
Crystal size (mm3)
Unit cell dimensions
monoclinic
P21/n (no.14)
0.20 · 0.20 · 0.05
monoclinic
P21/n (no. 14)
0.30 · 0.30 · 0.30
3
1
˚
a (A)
b (AA)
˚
c (A)
9.9505(10)
15.358(2)
11.8707(10)
90
9.449(3)
13.402(4)
13.969(6)
90
a (ꢁ)
b (ꢁ)
c (ꢁ)
108.40
90
107.20(3)
90
3
˚
Volume (A )
1721.3(3)
293(2)
1689.8(10)
293(2)
T (K)
Z
Dcalc. (mg/m3)
3.4. trans-[PtBr2{PPh2(CCl@CF2)}2] (2)
2
2.759
4
2.875
This complex was prepared in a similar fashion to 1
using 0.494 g, (8.3 · 10À4 moles) of K2PtBr4 and
0.471 g, (1.7 · 10À3 moles) of PPh2(CCl@CF2) to yield
2 as a yellow solid, m.p. 179–181 ꢁC, Yield = 54%. Calc.
for C28H20F4Cl2P2Br2Pt: C, 36.5; H, 2.2; Br, 17.4.
Found: C, 36.0; H, 2.0; Br, 17.7%. 31P{1H} NMR: d:
+18.4 [s, 1J(PtP) = 2715 Hz]. 19F NMR: d: À64.2 (trans)
[s, 4J(PtF) = 27 Hz], À66.9 (cis) [s, 4J(PtF) = 15 Hz]. Ra-
man (cmÀ1): 206 [(Pt–Br)]. IR (nujol, cmÀ1): 1691
[C@C], 1294, 1016 [C–F].
˚
k (A)
0.71073
11.850
1280
0.71073
12.219
1312
l(Mo Ka) (mmÀ1
F(000)
)
2h range (ꢁ)
Number of reflections
(unique)
2.24–24.99
3196 (3012)
2.15–24.99
3158 (2968)
R1/wR2
0.0612/0.1471
0.0899/0.1631
0.0490/0.0847
0.0855/0.0954
R1/wR2 (all data)
Largest differential
peak and hole (e A
2.318 and À2.476
1.455 and À1.260
À3
˚
)
3.5. trans-[PtI2{PPh2(CF@CF2)}2] (3)
OMNIC 5 software, over the range 4000–500 cmÀ1 (IR),
and 4000–100 cmÀ1 (Raman). Elemental analyses were
performed by the UMIST Chemistry Department
microanalysis service.
This complex was prepared in a similar fashion to 1
using 0.680 g, (8.7 · 10À4 moles) of K2PtI4 and 0.463 g,
(1.7 · 10À3 moles) of PPh2(CF@CF2) to yield 3 as an
orange solid. The remaining deep red-coloured filtrate
was extracted into chloroform (3 · 10 cm3) with shak-
ing. The organic layers were combined and the solvent
removed in vacuo. Washing of the resulting solid with
petroleum ether yielded 5 as a red solid (charactersing
data given in Section 3.7). Characterising data for 3 is
as follows: Orange solid, m.p. 140–144 ꢁC,
Yield = 51%. Calc. for C28H20F6P2I2Pt: C, 34.3; H,
2.0; I, 25.9. Found: C, 34.2; H, 1.9; I, 25.5%.
31P{1H} NMR: d: +0.6 [vt, 1/2|2J(PF) +
4J(PF)| = 18 Hz, 1J(PtP) = 2653 Hz]. 19F NMR: d:
À84.2 (trans) [dd, 2J(FF) = 37 Hz, 3J(FF) = 31 Hz,
4J(PtF) = 13 Hz], À94.1 (cis) [dd, 2J(FF) = 37 Hz,
3.2. X-ray crystallography
Data was collected at 293(2) K on a Nonius MACH3
diffractometer. The data for all the compounds was
solved using direct methods (SHELXS [24,25]). The struc-
tures were refined by full-matrix least squares on F2
using SHELX-97. All data used were corrected for Lor-
entz-polarisation factors and subsequently for absorp-
tion by the w-scan method. The non-hydrogen atoms
in the compounds were refined with anisotropic thermal
parameters. All hydrogen atoms in the compounds were
included in idealised positions and were refined isotrop-
ically. The crystallographic data is summarised in Table
2, with significant bond lengths and angles being listed
in Table 1.
4
3J(FF) = 117 Hz, J(PtF) = 50 Hz], À173.5 (gem) [ddvt,
1/2|2J(PF) +
4J(PF)| = 18 Hz,
3J(FF) = 31 Hz,3
3
J(FF) = 117 Hz, J(PtF) = 56 Hz]. Raman (cmÀ1): 152
[m(Pt–I)]. IR (nujol, cmÀ1): 1732 [C@C], 1319, 1161,
1057 [C–F].
3.3. cis-[PtBr2{PPh2(CF@CF2)}2] (1)
K2PtBr4 (0.607 g, 1.0 · 10À3 moles) was dissolved in
15 cm3 water and added to a solution of PPh2(CF@CF2)
(0.545 g, 2.0 · 10À3 moles) in 15 cm3 of ethanol. A white
solid, 1, precipitated after a few minutes, and the solu-
3.6. trans-[PtI2{PPh2(CCl@CF2)}2] (4)
This complex was prepared in a similar fashion to
1 using 0.511 g, (6.5 · 10À4 moles) of K2PtI4 and

2548
N.A. Barnes et al. / Inorganica Chimica Acta 358 (2005) 2543–2548
0.370 g, (1.3 · 10À3 moles) of PPh2(CCl@CF2) to yield
4 as a yellow-orange solid. The dimer 6 was extracted
from the filtrate as above to yield a deep red solid
(charactersing data given in Section 3.8). Characteris-
ing data for 3 is as follows: Yellow-orange solid,
m.p. 173–175 ꢁC (dec), Yield = 38%. Calc. for
C28H20F4Cl2P2I2Pt: C, 33.1; H, 2.0; I, 25.0. Found:
C, 33.3; H, 2.0; I, 25.4%. 31P{1H} NMR: d: +9.8 [s,
1J(PtP) = 2647 Hz]. 19F NMR: d: À63.4 (trans) [s,
Acknowledgements
The authors thank Ineos-Fluor for providing samples
of HFC-134a and HCFC-133a, Johnson Matthey for
the generous loan of platinum metal salts, and UMIST
for financial support. We acknowledge EPSRC for the
use of the Chemical Database Service at Daresbury.
4
4J(PtF) = 34 Hz], À68.2 (cis) [s, J(PtF) = 19 Hz]. Ra-
References
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Supplementary material
´ ´
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CCDC 260815 and 260816 contains the supplemen-
tary crystallographic data for this paper. These data
can be obtained free of charge via www.ccdc.cam.
ac.uk/data_request/cif, by emailing data_request@ccdc.
cam.ac.uk, or by contacting The Cambridge Crystallo-
graphic Data Centre, 12, Union Road, Cambridge
CB2 1EZ, UK; fax: +44 1223 336033.
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