Synthesis of gold(i) fluoroalkyl and fluoroalkenyl-substituted phosphine complexes and factors affecting their crystal packing

Article abstract of DOI:10.1039/c0dt01014f

A series of gold(i) phosphine complexes of the type [AuCl{PR ₂(R_f)}] (R = Et, i-Pr, Cy; R_f = CFCF ₂; R = Ph, R_f = CFCFH, CClCF₂, CCCF ₃, CF₃, i-C₃F₇, s-C ₄F₉) have been prepared and most have been structurally characterised. All of the complexes are monomeric in the solid state, and a number of secondary interactions are observed - including short intramolecular Au...F distances, metal-bound Au-Cl...H non-classical hydrogen bonds, fluorous domains and phenyl embraces. Only in the case of [AuCl{PEt ₂(CFCF₂)}] is an aurophilic interaction with an Au...Au contact less than the sum of the van der Waals radii observed. Even then, the distance, 3.3458(10) A, is longer than that previously observed for the related complex with R = Ph; R_f = CFCF₂.

Full text of DOI:10.1039/c0dt01014f

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www.rsc.org/dalton | Dalton Transactions
Synthesis of gold(I) fluoroalkyl and fluoroalkenyl-substituted phosphine
complexes and factors affecting their crystal packing†‡
Nicholas A. Barnes, Alan K. Brisdon,* F. R. William Brown, Wendy I. Cross, Ian R. Crossley, Cheryl Fish,
Christopher J. Herbert, Robin G. Pritchard and John E. Warren
Received 14th August 2010, Accepted 12th November 2010
DOI: 10.1039/c0dt01014f
A series of gold(I) phosphine complexes of the type [AuCl{PR2(Rf)}] (R = Et, i-Pr, Cy; Rf = CF CF2;
R = Ph, Rf = CF CFH, CCl CF2, C CCF3, CF3, i-C3F7, s-C4F9) have been prepared and most have
been structurally characterised. All of the complexes are monomeric in the solid state, and a number of
secondary interactions are observed – including short intramolecular Au ◊ ◊ ◊ F distances, metal-bound
Au–Cl ◊ ◊ ◊ H non-classical hydrogen bonds, fluorous domains and phenyl embraces. Only in the case of
[AuCl{PEt2(CF CF2)}] is an aurophilic interaction with an Au ◊ ◊ ◊ Au contact less than the sum of the
˚
van der Waals radii observed. Even then, the distance, 3.3458(10) A, is longer than that previously
observed for the related complex with R = Ph; Rf = CF CF2.
infinite chain.17 Aurophilic interactions are lost when bulkier
Introduction
trialkyl phosphines are present, in complexes such as [AuCl(Pi-
Pr3)].17 However, searches of the CSD database suggest that the
size of phosphine per se is a poor determinant of aurophilic
inte◦ractions, since for the complex of P(p-CH3C6H4)3 (cone angle =
Gold(I) phosphine complexes of the type [AuX(PR3)] have been
the subject of considerable interest due to their therapeutic value
as anti-cancer and anti-arthritic drugs,1 their chemiluminescent
properties,2 and also their emerging utility in a number of catalytic
processes, such as the hydration of alkynes.3
˚
145 ) an aurophilic interaction is observed, d(Au ◊ ◊ ◊ Au) = 3.375 A,
whilst for PPh3 (cone angle also 145◦) the closest Au ◊ ◊ ◊ Au contacts
18
The supramolecular chemistry of gold(I) phosphine complexes
also attracts much attention, principally due to the presence of
gold–gold interactions that some of these complexes exhibit in the
solid state.4 These dispersive interactions (termed “aurophilic”)5
are the result of attractive forces between two gold atoms with
closed-shell (5d10) configurations, and may be either intra- or
intermolecular in nature. Theoretical studies have shown that
hybridisation effects play no part in the origin of aurophilic
interactions, which are purely due to electron correlation and
relativistic effects.6–13 The strength of the interactions is, however,
greater than typically observed for van der Waals forces (estimated
to be 21–46 kJmol-1),14 and is therefore comparable in strength
to hydrogen bonding. The gold–gold distances observed in com-
pounds exhibiting aurophilic interactions typically lie between
distances observed for the Au2 molecule in the gaseous state
˚
are over 6.9 A. Crystallographic data have also shown that
bulky triaryl phosphines do not necessarily preclude the formation
of Au ◊ ◊ ◊ Au contacts. For example, the complexes [AuCl{P(m–
CF3C6H4)3}] and [AuCl{P(3,5–(CF3)2C6H3)3}]19 show aurophilic
˚
interactions of 3.0738(9) and 3.341(1) A respectively. It appears
that the presence of aurophilic interactions in triaryl phos-
phine complexes depends on the ability of such interactions to
compete effectively with other weak intermolecular forces. In
many gold(I) complexes of triaryl phosphines multiple phenyl
embraces20 between the aryl rings dominate the crystal packing,
for example [AuCl{P(o–CH3C6H4)3}], where molecules aggregate
through a back–to–back sextuple phenyl embrace.21 There also
exist examples, such as [AuCl{P(p–CH3C6H4)3}], for which there
are two known polymorphs, one with an aurophilic interaction
21
˚
of 3.375(1) A, and one with no particularly close gold–gold
˚
˚
approach.22 It should also be noted that the nature of the anionic
ligand, X, in [X–Au–L] complexes has an effect upon the strength
of the aurophilic interaction. Theoretical and experimental data
has suggested that the softer the ligand the stronger the gold–gold
contact.9–10
(2.47 A) and twice the van der Waals radius of gold (ca. 3.60 A).
Aurophilic interactions in gold(I) phosphine complexes usually
results in the formation of dimers, where two monomeric [XAuL]
units (featuring the gold atom in a linear geometry), are linked
together, usually in a perpendicular fashion (crossed-swords
motif), although linkage in a parallel or antiparallel orientation is
also known. These interactions are often observed for trialkyl
phosphines with small cone angles. Examples are also known
where monomeric units exhibit extended aggregation, for example,
[AuCl(PPhMe2)] which crystallises in both dimeric and trimeric
forms,15,16 and [AuCl(PMe3)]n, which is reported as an extended
Whilst numerous crystallographic studies on gold(I) phos-
phine complexes of aryl and alkyl phosphines have been re-
ported there has been considerably fewer on systems involv-
ing unsaturated alkenyl or alkynyl fragments. The structure of
[AuCl{P(CH CH2)3}] has been reported and exhibits a gold–
23
˚
gold interaction of 3.0934(5) A. [AuCl{PPh2(C CH)}] shows
no close gold–gold contacts, but instead links into dimers via
hydrogen bond interactions between the acetylenic proton and
the metal bound chloride.24 In contrast, the iodo- analogue
School of Chemistry, University of Manchester, Manchester, M13 9PL.
E-mail: alan.brisdon@manchester.ac.uk
† This publication is part of the web themed issue on fluorine chemistry.
‡ CCDC reference numbers 789438–789445. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/c0dt01014f
˚
[AuI{PPh2(C CH)}] displays a Au ◊ ◊ ◊ Au contact of 3.0625(9) A.
When the phenyl groups are substituted for more bulky
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was prepared by reacting Ph2P(CF CF2) with LiAlH4,36 whilst
Ph2P(CCl CF2) and Ph2P(C CCF3) were obtained from the
reaction of CF3CH2Cl and CF3CH2CHF2 respectively with two or
three equivalents of base and Ph2PCl.37,38 Ph2PCF3 was prepared
using the method reported by Caffyn39 whilst Ph2P(i-C3F7) and
Ph2P(s-C4F9) were obtained from the reaction of Ph2P(SiMe3)
with the appropriate perfluoroalkyliodide, as previously reported
by us.40
substituents, such as in [AuCl{Pi-Pr2(C CH)}] then aurophilic
interactions are no longer observed.25 Thus, a fine balance
between a combination of steric effects, crystal packing forces,
electronic contributions from the co–ligands and a number of
different secondary interactions are all important in determining
the supramolecular chemistry of gold(I) phosphine complexes.
Many such complexes do exhibit short Au ◊ ◊ ◊ Au distances, but
deconvolution of the individual contributions giving rise to
these interactions is difficult to achieve. The current generally-
accepted view is that aurophilic, and possibly other metallophilic,
interactions have a structure directing influence.26,27 However, it
has also been pointed out that a strong correlation exists between
the structures and bonding motifs found for some R3EX2 (E =
P, As; X = Cl, Br, I) compounds and [(R3P)AuX] complexes,28
which suggests that the aurophilic interaction is less significant
than other packing effects.
Complexation of the phosphines to form the gold(I) complexes
[AuCl{PR2Rf}] was achieved by preparing the chloro-gold thiodi-
ethanol or tht intermediate and subsequent displacement of the
weakly-bound ligand by the appropriate phosphine, Scheme 1.
1
In all cases, following complexation a shift in the 31P{ H}NMR
resonance of the phosphine ligand is observed; typically, these
coordination shifts are ca. 30 to 55 ppm to higher frequencies
compared with the starting phosphines. Coordination also results
in changes in the observed P–F coupling constants within the
ligand. Generally, a reduction in the magnitude of these coupling
constants is observed due to reduction of the through-space, lone-
pair assisted coupling mechanism.35 For example for the i-C3F7-
containing system, the 3J(PF) coupling falls from 18 Hz in the free
ligand to 8.6 Hz in the gold(I) complex.
We note with interest that very few gold(I) complexes of
fluorine-containing phosphine ligands have been published.
We have previously reported the gold(I) complexes of fluo-
rovinyl substituted phosphines, [AuCl{PPh2(CF CF2)}], and
[AuCl{PPh(CF CF2)2}].29 For the former we were able to
obtain structural data which showed that the complex ag-
gregates as dimers in the solid–state with a short Au ◊ ◊ ◊ Au
˚
distance of 3.1945(5) A. Apart from the complex described
above, details of nine other gold(I) halo-phosphine complexes
of this type are contained in the CSD database. These in-
clude the complexes of phosphines containing 3-, 4- and 3–
5-CF3-substituted phenyl rings (Au ◊ ◊ ◊ Au = 3.0738, 3.028 and
13
˚
3.341 A respectively); and the bidentate ligands Ph2PCF2PPh2
30
˚
(Au ◊ ◊ ◊ Au = 8.103 A) and (t-BuPCF2)2(AuCl)2 (Au ◊ ◊ ◊ Au =
7.096 A).31 Other examples include the (4-pentafluorophenyl-4H-
˚
32
˚
phospholo(3,2-b:4,5-b¢)dithiophene-P) (Au ◊ ◊ ◊ Au = 3.079 A)
and tris-pentafluorophenylphosphine 4.819 A complexes and
33
˚
those of the fluorophosphines difluoro(dimethyl-amino) phos-
˚
phine (6.278 A) and 2,5-dimethylphenyl(difluoro) phosphine
34
˚
(6.620 A). It therefore seems that gold(I) complexes of
fluoroorgano-phosphines may be worthy candidates to investigate
for the presence of Au ◊ ◊ ◊ Au interactions. However, the presence
of fluorine may also introduce other packing motifs. For example,
we have shown that in a series of palladium(II) and platinum(II)
complexes containing fluorovinyl phosphine ligands the observed
structures appear to be controlled by a fine balance of fluorophilic
and hydrogen bonding interactions. For example, the solid-state
structure of [PtCl2{i-Pr2P(CF CF2)}2] is composed of a 2 : 1
mixture of the cis- and trans-isomers arranged in such a way as
to form fluorocarbon domains whilst for the trans-only palladium
analogue, [PdCl2{i-Pr2P(CF CF2)}2], hydrogen-bonding is the
dominant secondary interaction.35a
Based on our previous findings, and the limited number of
known gold(I) complexes containing organofluorine-substituted
phosphines, we now report a series of such complexes in order
to probe the relative importance of hydrogen bonds, fluorous
domains and aurophilic interactions in determining the structural
mofits observed in their solid state structures.
Scheme 1 Synthesis of gold(I) phosphine complexes.
In order to ascertain whether short Au ◊ ◊ ◊ Au interactions are
present in these gold(I) complexes (as they are in the previously re-
ported Ph2P(CF CF2)-containing complex) attempts were made
to grow single crystals for X-ray analysis. Crystals of complexes
1, 2, 4 and 6–9 were obtained from slow evaporation of solvent
from CH2Cl2–hexane solutions. We were unable to obtain suitable
crystals for complexes 3 and 5.
A summary of the crystallographic parameters and selected
bond lengths and angles for the complexes are given in Table 1.
All of the complexes adopt a near linear arrangement, with P–Au–
Cl bond angles of between 176.17(13) and 179.50(7)◦. The Au–P
and Au–Cl distances are similar for the majority of the complexes
˚
and range between 2.215(3) – 2.243(5) and 2.261(5) – 2.313(2) A
respectively. The Au–P distances are similar to, or slightly shorter
than is typically observed in phosphine-containing complexes,
41
˚
for example [AuCl(PCy3)], d(Au–P) = 2.242(3) A, [AuCl(PEt3)],
Results and discussion
42
˚
d(Au–P) = 2.232(4) A and slightly longer than for complexes
˚
The synthesis of the fluorinated ligands R2P(CF CF2) (R = Et,
i-Pr and Cy) have been reported previously.36 Ph2P(CF CFH)
containing phosphites, for example d(Au–P) = 2.192(5) A in
44
[AuCl{P(OPh)3}]43 and 2.211(4) A in [AuCl{P(OMe)3}].
˚
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Table 1 Selected lengths and angles for crystallographically-characterised complexes
29
1
2
4
6
7
8
9a
[AuCl{PPh2(CF CF2)}
Au–Cl
2.276(4)
2.215(3)
176.17(13)
5.622
2.286(4)
2.224(4)
176.56(17)
3.947
2.2728(17)
2.2186(14)
178.61(7)
3.3458
2.261(4)
2.228(4)
177.76(19)
5.489
2.2731(56)
2.2164(55)
178.88(24)
5.196
2.3011(51)
2.2433(51)
178.32(20)
4.502
2.3126(17)
2.2790(19)
2.233(2)
2.226(2)
179.50(7)
178.18(7)
5.624
2.287(2)
2.216(2)
177.36(8)
Au–P
P–Au–Cl
Au ◊ ◊ ◊ Au
3.187
2.635 H ◊ ◊ ◊ F
Other short 2.76 H ◊ ◊ ◊ Cl 3.415 Cl ◊ ◊ ◊ Cl 3.186 Au ◊ ◊ ◊ F 2.805 H ◊ ◊ ◊ Cl 2.614 F ◊ ◊ ◊ H 3.249 F ◊ ◊ ◊ F 2.643 F ◊ ◊ ◊ F
contacts
2.36 H ◊ ◊ ◊ Cl 3.128 Au ◊ ◊ ◊ F
3.143 Au ◊ ◊ ◊ F 2.645 F ◊ ◊ ◊ H 3.357 F ◊ ◊ ◊ F 2.827 F ◊ ◊ ◊ F
2.846 H ◊ ◊ ◊ Cl
3.216 Au ◊ ◊ ◊ F 3.148 Au ◊ ◊ ◊ F
3.296 Au ◊ ◊ ◊ F
a Two unique molecules in the asymmetric unit, one of which is disordered, see text.
which crystalises in the P21/n space group. The anticipated
linear molecular structure is observed, as shown in Fig. 2(a).
The extended structure viewed down the a-axis is shown in Fig.
2(b). An edge-to-face (EF)4 embrace20 is observed between phenyl
groups of adjacent molecules resulting in the formation of pairs
of molecules with anti-parallel Au–Cl bonds and a P–P separation
The structure of [AuCl{PPh2(CF CFH)}], 1, is shown in Fig.
1(a). The Au–Cl and Au–P distances are very similar to those found
in [AuCl{PPh2(CF CF2)}], which is unsurprising given that pre-
vious work has shown there to be little differences in the steric and
electronic properties of Ph2P(CF CF2) and Ph2P(CF CFH).35
However, the extended structure of 1 is significantly different from
that of [AuCl{PPh2(CF CF2)}] where a dimeric-based motif is
observed arising from a short Au ◊ ◊ ◊ Au interaction. However, for 1
the most significant non-bonded interactions are hydrogen-based
instead. An intermolecular hydrogen bond is formed between the
hydrogen of the difluorovinyl group (H2) and the gold-bound
˚
across the embrace of 7.141 A. There are two intermolecular
interactions less than the sum of the relevant van der Waals
˚
radii. An interaction of 3.415 A is formed between the gold-
bound chlorine and the chlorine of a chlorodifluorovinyl group
of an adjacent molecule. The chloride ligand is also involved in
a hydrogen bond with one of the meta-hydrogens of a phenyl
ring, similar to that found in complex 1. A short intramolecular
˚
chloride of an adjacent molecule◦(d(H ◊ ◊ ◊ Cl) = 2.76 A, d(C ◊ ◊ ◊ Cl) =
˚
3.661(7) A, ∠C–H ◊ ◊ ◊ Cl = 163 ). We have previously observed
˚
Au ◊ ◊ ◊ F distance d(Au1 ◊ ◊ ◊ F1) = 3.128(12) A is also observed. This
similar metal-halide to vinyl C–H interactions in palladium(II) and
platinum(II) complexes of Ph2P(CF CFH).35b An intramolecular
type of metal-fluorine interaction is commonly observed in metal
complexes of CF CF2 and CF CFH–containing phosphines,
due to the orientation of the ligand over the metal centre.35,35b
˚
hydrogen-chlorine interaction◦(d(H ◊ ◊ ◊ Cl) = 2.36 A, d(C ◊ ◊ ◊ Cl) =
˚
3.052(7) A, C–H ◊ ◊ ◊ Cl = 131 ) is also observed from the gem-
˚
The shortest Au ◊ ◊ ◊ Au distance is 3.947(1) A, which is somewhat
fluorine to one of the meta-hydrogens of a phenyl ring. The
former of these interactions generates a helical arrangement which
propagates parallel to the b-direction, as shown in Fig. 1(b). The
packing generated results in the shortest Au ◊ ◊ ◊ Au contact being
longer than is normally viewed as an aurophilic interaction.27
˚
5.622 A, significantly more than twice the sum of the van der
Waals radius of gold.
Fig. 2 (a) ORTEP representation (thermal ellipsoids at 30%) and (b)
packing diagram, viewed down the a-axis of 2, [AuCl{PPh2(CCl CF2)}].
Reaction of the trifluoropropynyl-containing phosphine,
PPh2(C CCF3), according to Scheme 1, resulted in the formation
of [AuCl{PPh2(C CCF3)}], 3, in good yield. Confirmation of the
identity of the complex comes from analytical and spectroscopic
data. Formation of the gold complex resulted in a co-ordination
shift, DdP, of 29.4 ppm to higher frequency, along with a small shift
in the position of the 19F-NMR resonance (DdF = -1.3). However,
we were unsuccessful in obtaining crystals for X-ray analysis work.
Fig. 1 (a) ORTEP representation (thermal ellipsoids at 30%) and (b)
packing diagram viewed down the b-axis for, 1, [AuCl{PPh2(CF CFH)}].
When PPh2(CCl CF2) is used instead of PPh2(CF CF2) the
complex [AuCl{PPh2(CCl CF2)}], 2, is formed as a white solid
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Having made modifications to the unsaturated fluorinated
ligand of our prototypical Ph2P(CF CF2) system we turned
our attention to preparing a series of complexes in which the
phenyl groups of the Ph2P(CF CF2) ligand were replaced with
Et, i-Pr and Cy. These ligands have been made before, and from
their square planar palladium(II), platinum(II) and rhodium(I)
complexes the average cone angles were calculated as 152, 165
and 169◦ respectively, compared with 163◦ for Ph2P(CF CF2).35
Although we were not able to obtain crystals of the i-Pr-containing
complex, 5, both the smaller ethyl, and larger cyclohexyl-
containing analogues, 4 and 6, did yield crystals suitable for X-ray
diffraction studies.
In the solid-state structure of 4 the gold centre lies in an approx-
imately linear geometry, with a P–Au–Cl angle of 176.17(13)◦,
Fig. 3(a). Stacks of parallel aligned molecules exist in the b-
direction, which when viewed down the c-axis appear as two
[AuCl{PEt2(CF CF2)}] units linked by an Au ◊ ◊ ◊ Au interaction
Fig. 4 (a) ORTEP representation (thermal elipsoids at 30%) and (b)
packing diagram viewed down the b-axis for 6, [AuCl{PCy2(CF CF2)}].
PCy2(CF CF2) of 176◦, which is slightly larger than that obtained
previously from the square-planar bis-phosphine palladium(II)
and platinum(II) complexes.35 The fact that the angle determined
from this gold(I) complex is larger is not particularly surprising,
given that the coordination number in this complex is lower, so
reducing the steric interaction with the other ligands around the
metal centre.
◦
˚
of 3.3458(10) A, with a Cl–Au ◊ ◊ ◊ Au–Cl torsion angle of 116.7(5) .
This Au ◊ ◊ ◊ Au distance is significantly longer than that seen in
[AuCl{PPh2(CF CF2)}]2 (3.1945(5) A),29 but is shorter than that
˚
˚
observed for [AuCl(PEt3)] (3.615(2) A), which is regarded as a
borderline case of an aurophilic interaction.27 Between adjacent
dimers lie the perfluorovinyl groups with an intramolecular
˚
˚
Au ◊ ◊ ◊ F6B distance of 3.186(9) A. This is approximately 0.6 A less
than the sum of the van de Waals radii of gold and fluorine. Such
an intramolecular fluorine interaction with a low coordination
metal centre has been observed before, for example in the solid-
state structure of trans-[PdCl2{PPh2(CF CFH)}2].35b The result
of these interactions, as shown in Fig. 3(b), is to “cap” the end
of each pair of gold complexes, so providing a four-coordinate
geometry around the gold centre. The fluorovinyl groups aggregate
such that when viewing the unit cell from the a-direction alternate
fluorous and hydrocarbon layers are visible, Fig. 3(c).
In the extended structure, shown in Fig. 4(b), molecules stack in
˚
the b-direction. The closest Au ◊ ◊ ◊ Au distance is 5.490(3) A, which
is beyond what is considered as an aurophilic interaction. A weak
intermolecular hydrogen bond (d(Cl ◊ ◊ ◊ H1) = 2.81, d(Cl ◊ ◊ ◊ C) =
3.742(16) A, ∠Cl ◊ ◊ ◊ H ◊ ◊ ◊ C = 158 ) between the chloride ligand of
one molecule and the geminal hydrogen of one of the cyclohexyl
substituents of the next molecule is propagated in the b-direction.
A number of intramolecular contacts exist; most notable of these
◦
˚
˚
˚
is between Au1 and F3, which at 3.144(10) A is 0.63 A less than the
sum of the van der Waals radii of gold and fluorine, and is similar
to the feature observed in complexes 2 and 4. However, unlike in 2
and 4 it is not possible for another molecule to approach and form
an Au ◊ ◊ ◊ Au interaction because of the bulkier cyclohexyl rings.
The third set of modifications to the ligand set that we undertook
was to replace the fluorovinyl group in Ph2P(CF CF2) with
other fluorocarbon fragments. The systems we chose resulted in
complexes of Ph2P(CF3), 7, Ph2P(i-C3F7), 8, and Ph2P(s-C4F9), 9.
Complex 7 was formed in ca. 60% yield by displacement of
the weakly bound tht ligand from [AuCl(tht)] by Ph2PCF3. It
is noteworthy that despite a number of different routes being
known to Ph2PCF3, and it first being reported in 1962 there is
only one known complex of this ligand, [PtCl2{PPh2CF3}2] and
even this has not been characterised crystallographically.45 The
solid-state structure of complex 7 is shown in Fig. 5(a). It shows the
anticipated molecular structure and from this we calculate the cone
angle to be 105◦. This is considerably smaller than that reported
(142◦) by Tolman derived from measuring space-filling models,46
although later work suggests that the size of CF3-containing
phosphines may have been overestimated.47 The Au–P bond length
is slightly longer, and the Au–Cl distance a little shorter than
that found in the analogous Ph2P(CF CF2)-containing complex.
This is consistent with previous work which suggests that the
perfluorovinyl-containing phosphine is somewhat less donating
than diphenylfluoroalkylphosphines.29 Molecules stack in a head-
to-tail fashion along the c-direction. When viewed down the a-axis,
Fig. 5(b), the packing diagram shows that the gold atoms cannot
Fig. 3 (a) ORTEP representation (thermal ellipsoids at 30%) of 4,
[AuCl{PEt2(CF CF2)}], and (b) and (c) two representations of the
packing arrangement.
The solid-state structure of [AuCl{PCy2(CF CF2)}] shows
that 6 also adopts the anticipated molecular arrangement, as
shown in Fig. 4(a). From these data we determine a cone angle for
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stacks align in the same direction in the ab-plane, as opposed to
back-to-back as observed here. It therefore appears the generation
of fluorous domains is preferred in 8 and so influences the
observed packing. Once again relatively short Au ◊ ◊ ◊ F distances
are observed, in this case from one of the fluorines of each CF3
˚
group, with distances of ca. 3.25 and 3.36 A.
The solid-state structure of complex 9, [AuCl{PPh2(s-C4F9)}] is
shown in Fig. 7(a). The unit cell contains two unique molecules,
one of which shows disorder within the s-C4F9 fragment. Interest-
ingly, the disorder involves swapping the CF3 and CF2CF3 groups,
as shown in Fig. 7(b), and as such corresponds to the two possible
isomers of the C-chiral phosphine. The bond lengths of the non-
disordered molecule show the longest Au–Cl and Au–P distances
of all those reported here. The steric demand of this ligand is
determined to be 187◦. As far as we are aware this is the first
complex of this ligand to have been reported and also the first to
be structurally characterised.
Fig. 5 (a) ORTEP representation (thermal elipsoids at 30%) and (b)
packing diagram looking down the a-axis of 7, [AuCl{PPh2(CF3)}].
line up to make a close contact, although the molecules get close
to approaching a crossed-sword motif. Instead an (EF)4 embrace
˚
is observed with a P ◊ ◊ ◊ P separation of 8.343 A. The shortest
˚
Au ◊ ◊ ◊ Au distance observed is 5.196 A with a Cl–Au ◊ ◊ ◊ Au–Cl
torsion angle of 142.9◦. The only observed interactions that are
less than the sum of the relevant van der Waal’s radii are non-
classical hydrogen bonds formed between two of the fluorines of
the CF3 group and meta-hydrogens of the aromatic rings; these lie
˚
within the range 2.614 to 2.645 A.
Increasing the size of the fluorinated group from CF3 to i-
C3F7 generates the Ph2P(i-C3F7) complex, 8, which is, as far as
we are aware, only the third complex of this ligand to have been
reported,48 although others are known.49 The gold(I) complex of
this ligand crystallises in the C2/c space group, the molecular
structure is shown in Fig. 6(a). We calculate the cone angle of the
ligand as 186◦, which is much larger than that obtained (156◦
48
and 161◦49) for the more sterically-crowded trans-[PtCl2{Ph2P(i-
C3F7)}2] complex.48 A packing diagram looking down the c-axis is
shown in Fig. 6(b). A crossed-sword motif is observed for the gold-
chloride parts of molecules stacked upon each other. This results
Fig. 7 (a) ORTEP representation (thermal ellipsoids at 30%) of the
disordered molecule in the unit cell, (b) disorder in the s-C4F9 unit in
one unique molecule and (c) packing diagram of 9, [AuCl{PPh2(s-C4F9)}].
˚
in the shortest Au ◊ ◊ ◊ Au contact being 4.50 A with a Cl–Au ◊ ◊ ◊ Au–
Cl torsion angle of 97.9◦. This is significantly nearer to the angle
traditionally observed in a classical aurophilic crossed-sword motif
than was observed for complex 7. Adjacent stacks are arranged
back-to-back which gives rise to fluorous domains due to the
close approach of neighbouring i-C3F7 groups. A related packing
motif has been observed previously for [AuCl{P(p-CH3C6H4)3}]
(space group P21/c),16,50 except in that case adjacent crossed-sword
Consideration of the extended packing, Fig. 7(c), shows a
somewhat different arrangement from that formed by the i-C3F7
analogue. The presence of fluorous domains is again obvious,
resulting in relatively short F ◊ ◊ ◊ F interactions being observed.
˚
For example, the F(18) ◊ ◊ ◊ F(18)¢ interaction of 2.643(11) A, more
˚
than 0.3 A shorter than the sum of two fluorine van der Waals
radii. A number of short Au ◊ ◊ ◊ F intramolecular contacts (3.216
˚
and 3.296 A) are also observed between the CF2 fluorines and
gold. There also appears to be a pseudo-phenyl embrace of the
s-C4F9 group with two of the phenyl rings. This interaction, which
extends in the c-direction, results in stacks of 9, and is facilitated by
the alternate anti-parallel arrangement (Cl–Au ◊ ◊ ◊ Au–Cl torsion
angle = 1.8◦) of [AuCl{PPh2(s-C4F9)}] molecules.
Conclusions
By systematically varying components of the [AuCl{PR2Rf}]
system we have generated a series of compounds which has
allowed us to investigate the effect that changes of the R and
Rf groups have on the secondary interactions in the solid state
structures of these complexes. In the majority of complexes an
Fig. 6 (a) ORTEP representation (thermal ellipsoids at 30%) and (b)
packing diagram viewed down the c-axis of 8, [AuCl{PPh2(i-C3F7)}].
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against F2 using SHELXTL51 or SHELX-9752 with H-atoms in
ideal positions. All non-H atoms were modelled with anisotropic
displacement parameters. For complexes 6 and 7 C1 to C7 and
C1–C13, respectively, were restrained using the ISOR command.
The SHELTX SAME command was used to ensure that the
CF3 and CF2CF3 groups were treated in the same way in the
two chiral forms adopted by one of the two molecules in the
unit cell of 9. Figures were produced using PLATON.53 Table 2
lists some of the more important crystallographic data for the
gold(I) complexes. We also obtained X-ray data for the oxidised
thiodiethanol product. These data have been reported before, but
on twinned crystals.54 Our data, of somewhat higher precision, are
included in the supplementary information, and along with data
for the gold(I) complexes have been deposited at the Cambridge
Crystallographic Data Centre (CCDC).‡
˚
intramolecular Au ◊ ◊ ◊ F interaction of ca. 3.2 A (which is less than
the sum of the van der Waals radii of gold and fluorine) is ob-
served. The previously recorded data for [AuCl{PPh2(CF CF2)}]
also displays this Au ◊ ◊ ◊ F interaction, and a short Au ◊ ◊ ◊ Au
distance. However, this Au ◊ ◊ ◊ Au interaction is not replicated
even when apparently small changes are made to the ligand,
such as complex 1, [AuCl{PPh2(CF CHF)}]. The structures of
[AuCl{Et2P(CF CF2)}], 4, and [AuCl{Ph2P(i–C3F7)}], 8, show
that when fluorous domains are present in the crystal packing
there appears to be a tendency towards closer Au ◊ ◊ ◊ Au approach.
However, in the series of complexes reported here only 4 displays
what would be considered to be a close Au ◊ ◊ ◊ Au interaction.
Complexes such as 7 and 8 begin to approach the typical crossed–
swords motif of an aurophilic interaction, but in both cases
other packing motifs dominate; i.e. (EF)4 phenyl embraces in
the extended structure of 7. It is interesting to note that the
˚
Synthesis of gold(I) complexes
Au ◊ ◊ ◊ Au separation in 8 is 4.502 A, which is much closer
than in the Ph2PCF3 complex 7, despite the cone angle for 8
being much larger than that of 7. This suggests that predictions
made concerning an Au ◊ ◊ ◊ Au interaction based solely on steric
arguments are unreliable. The majority of the structures here show
that either non–conventional Au–Cl ◊ ◊ ◊ H–C hydrogen bonding
(in the case of 1 and 6), formation of phenyl embraces (for
2, 7 and 9) or the potential for fluorous domains (such as in
8 and 9), are more dominant supramolecular synthons in this
series of gold(I) phosphine halide complexes than aurophilic
interactions. This further demonstrates the complicated nature
of the supramolecular chemistry of gold(I) phosphine complexes.
Synthesis of gold complexes was achieved by one of two methods
as shown in Scheme 1.
Via a thiodiethanol complex for 1 and 3–6: In a typical procedure
0.5 g (one equivalent) of sodium tetrachloroaurate dissolved
in water (10 cm3) was added dropwise to an aqueous solution
containing three equivalents of thiodiethanol dissolved in water
(15 cm3) which was cooled in an ice bath. A yellow precipitate was
formed initially which redissolved on stirring. After discharge of
the yellow colour of the mixture a solution of one equivalent of
the appropriate phosphine dissolved in chloroform (25 cm3) was
added dropwise with stirring. The resulting colourless mixture
was stirred vigorously for a further 2 h during which time the
reaction mixture was allowed to warm to room temperature.
The chloroform layer was then separated and the aqueous phase
extracted with a further 20 cm3 of chloroform. The organic layers
were combined before being removed by rotary evaporator to leave
a white solid material which was washed with hexane and placed in
a refrigerator overnight resulting in white solids which were dried
in vacuo to yield the desired products.
Via a tht complex for 2 and 7–9: K[AuCl4] (0.2 g, 0.5 mmol) was
dissolved in ethanol (5 cm3) and water (2 cm3). Tetrahydrothio-
phene (0.1 ml, 1.1 mmol) was added dropwise, and the mixture
stirred for 15 min, during which time the solution became yellow,
then white. The mixture was filtered and the white solid dried in
vacuo, before being placed in a flask containing CH2Cl2 (5 cm3).
A solution of the appropriate phosphine (0.47 mmol) in CH2Cl2
(1 cm3) was added and the mixture allowed to stir overnight. The
volatile materials were removed in vacuo, to afford the desired
products as white solids.
Experimental
All ligand synthesis reactions were carried out under an inert at-
mosphere of argon or dinitrogen in flame dried glassware. Diethyl
ether and THF were dried over sodium wire for ca 1 d and sub-
sequently refluxed over sodium/benzophenone under a nitrogen
atmosphere. CF3CFH2 and CF3CClH2 (ICI Klea), CF3CH2CHF2
(Honeywell), i-C3F7I, s-C4F9I (Apollo Scientific) BuLi (2.5 M
in hexanes, Acros), PEt2Cl (Lancaster), Me3SiCF3, PPh2Cl, Pi-
Pr2Cl, PCy2Cl (Aldrich), Na[AuCl4] (Johnson Matthey) were used
as supplied after verification of their purity. PPh2(CF CF2),
PPh2(CF CHF) and PPh2(CCl CF2) were prepared as de-
scribed previously.29,36 NMR spectra were recorded on Bruker
DPX200 or Avance III (400 MHz) spectrometers. Peak positions
are quoted in ppm relative to external CFCl3 (19F), 85% H3PO4
(31P) and TMS (1H, 13C) using the high frequency positive
convention and coupling constants are given in Hz. 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
the School’s microanalytical service.
[AuCl{PPh2(CF CFH)}], 1. Yield = 68%. White solid, Cal-
culated for C14H11F2PClAu: C, 35.0; H, 2.3; Cl, 7.4; Found; C,
1
2
35.1; H, 2.5; Cl, 7.0. 31P{ H} NMR (CDCl3): 19.0 [dd, J(PF) =
41, J(PF) = 16]. 19F NMR (CDCl3): –148.5 (cis) [ddd, J(PF) =
3
3
2
3
2
16, J(HF) = 74, J(FF) = 143], –164.1 (gem) [ddd, J(PF) = 41,
X-ray crystallography
3J(HF) = 6, J(FF) = 143]. H NMR (CDCl3): 7.81 [1H, ddd,
3
1
Data were collected on crystals prepared by slow solvent evapora-
tion of CH2Cl2–hexane solutions of the complexes, on Rigaku
AFC6S and Nonius MAC3 CAD4 diffractometers. All the
data obtained from the complexes were corrected for Lorentz,
polarisation and absorption using the psi-scan method. X-ray
structural data solution was by direct methods and refined
2J(HF) = 74, 3J(HF) = 6, 3J(PH) = 15], 7.41–7.79 [10H, m, aryl].
13C{ H} NMR (CDCl3): 124.7 [Ci, d, J(PC) = 63], 129.9 [Cm,
1
1
3
2
d, J(PC) = 12], 133.3 [Cp, s], 134.3 [Co, d, J(PC) = 11], 147.5
1
2
1
[CF CFH, ddd, J(CF) = 265.6, J(CF) = 70.3, J(PC) = 35.0],
152.9 [CF CFH, ddd, J(CF) = 259.3, J(CF) = 63.1, J(PC) =
1
2
2
10].
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[AuCl{PPh2(CCl CF2)}], 2. Yield = 72%. White solid, Cal-
culated for C14H10F2PCl2Au: C, 32.8; H, 1.9; Cl, 13.8; Found: C,
1
3
33.5; H, 1.7; Cl, 13.6. 31P{ H} NMR (CDCl3): 27.3 [d, J(PF) =
16]. 19F NMR (CDCl3): –61.0 (trans) [d, J(FF) = 5], -67.8 (cis)
2
[dd, 2J(FF) = 5, 3J(PF) = 16]. 1H NMR (CDCl3): 7.72–7.50 [10H,
aryl, m]. 13C{ H} NMR (CDCl3): 84.7 [ddd, CCl CF2, 2J(CF) =
1
32.8, 14.5, 1J(PC) = 53.1], 125.9 [d, CI, 1J(PC) = 63.7], 129.9 [d, Cm,
3J(PC) = 12.6], 133.3 [d, Cp, 4J(PC) = 2.9], 134.3 [d, Co, 2J(PC) =
15.5], 159.5 [ddd, CCl CF2, 1J(CF) = 306.1, 302.3, 2J(PC) = 20.3].
[AuCl{PPh2(C CCF3)}], 3. Yield = 73%. White solid. Cal-
culated for C15H10F3PClAu: C, 35.3; H, 2.0; Cl, 6.9; Found: C,
1
37.4; H, 2.1; Cl, 6.3. 31P{ H} NMR (CDCl3): 5.5 [br. s]. 19F NMR
4
1
(CDCl3): -52.2 [d, J(PF) = 2.4]. H NMR (CDCl3): 7.72–7.50
1
1
[10H, aryl, m]. 13C{ H} NMR (CDCl3): 85.7 [dq, J(CP) = 31,
3J(CF) = 7], 90.3 [qd, 2J(CF) = 52, 2J(CP) = 1.2],111.6 [qd, 1J(CF) =
259, J(CP) = 1.4]. IR (nujol, cm-1): 2223 n(C C), 1245, 1166
3
(C–F).
[AuCl{PEt2(CF CF2)}], 4. Yield = 55%. White solid, mp. 37–
8 ◦C. Calculated for C6H10F3PClAu: C, 17.9; H, 2.5; Cl, 8.8; Found:
1
C, 18.3; H, 2.4; Cl, 8.3. 31P{ H} NMR (CDCl3): 20.9 [dd, 2J(PF) =
3
2
27, J(PF) = 7]. 19F NMR (CDCl3): -78.8 (trans) [dd, J(FF) =
3
2
3
36, J(FF) = 32], -99.1 (cis) [ddd, J(FF) = 36, J(FF) = 121,
3J(PF) = 7], -186.7 (gem) [ddd, 3J(FF) = 32, 3J(FF) = 121, 2J(PF) =
27]. 13C{ H} NMR (CDCl3): 8.2 [s, CH3], 17.0 [d, CH2, 1J(PC) =
1
39.6], 121.9 [dddd, CF CF2, 1J(CF) = 264.6, 2J(CF) = 46.6, 13.5,
1J(PC) = 61.8], 159.1 [dddd, CF CF2, J(CF) = 307.1, 291.7,
1
2J(CF) = 39.6, J(PC) = 25.1]. H NMR (CDCl3): 2.40 ppm [m,
4H, CH2CH3], 1.18 ppm [m, 6H, CH2CH3]. IR (nujol, cm-1): 1727
n(C C), 1318, 1153, 1065 n(C–F).
2
1
[AuCl{PPri2(CF CF2)}], 5. Yield = 64%. White solid, mp.
◦
63–5 C. Calculated for C8H14F3PClAu: C, 22.3; H, 3.3; Cl, 8.2;
1
Found: C, 22.1; H, 3.5; Cl, 7.8. 31P{ H} NMR (CDCl3): 42.7 [dd,
3
2J(PF) = 19, J(PF) = 7]. 19F NMR (CDCl3): - 78.0 (trans) [dd,
2J(FF) = 34, 3J(FF) = 31], - 97.8 (cis) [ddd, 2J(FF) = 34, 3J(FF) =
3
3
3
121, J(PF) = 7], - 181.8 (gem) [ddd, J(FF) = 31, J(FF) = 121,
2J(PF) = 19]. 13C{ H} NMR (CDCl3): 17.7 [s, CH(CH3)2], 18.0 [d,
1
CH(CH3)2, 2J(PC) = 5.8], 23.0 [d, CH(CH3)2, 1J(PC) = 35.7], 121.4
1
2
1
[dddd, CF CF2, J(CF) = 264.6, J(CF) = 45.4, 13.5, J(PC) =
57.0], 159.9 [dddd, CF CF2, 1J(CF) = 308.1, 291.7, 2J(CF) = 39.6,
2J(PC) = 23.2]. 1H NMR (CDCl3): 3.10 ppm [m, 2H, CH(CH3)2],
1.36 ppm [m, 12H, CH(CH3)2]. IR (nujol, cm-1): 1732 n(C C),
1317, 1154, 1063 n(C–F).
[AuCl{PCy2(CF CF2)}], 6. Yield = 57%. White solid, Calcu-
lated for C14H22F3PClAu: C, 32.9; H, 4.3; Cl, 6.9; Found: C, 33.6;
1
H, 4.9; Cl, 6.8. 31P{ H} NMR (CDCl3): 33.7 [d, 2J(PF) = 20]. 19
F
NMR (CDCl3): -78.6 (trans) [dd, 2J(FF) = 35, 3J(FF) = 30], -97.8
(cis) [dd, 2J(FF) = 35, 3J(FF) = 122], -179.9 (gem) [ddd, 3J(FF) =
3
2
1
30, J(FF) = 122, J(PF) = 20]. H NMR (CDCl3): 1.80 ppm [b,
10H], 1.29 ppm [b, 12H]. IR (nujol, cm-1): 1735 n(C C), 1308,
1150, 1048 n(C–F).
[AuCl(PPh2CF3)], 7. Yield: 57%. White solid. Calculated for
1
C13H10F3PClAu: H 2.07 P 6.37 Found: H 1.96 P 7.0. 31P{ H} NMR
(CDCl3): d 30.6 [q, 2J(PF) = 83.6 Hz]; 19F NMR (CDCl3): d -57.6
2
1
ppm [d, J(PF) = 83.1 Hz]; H NMR: d 7.64–7.72 [ortho-CH m,
4H], 7.50–7.57 [para-CH, m, 2H], 7.42–7.48 [meta-CH, m, 4H];
13C NMR (CDCl3): d 122.6 ppm [d, 1J(PC) = 41.0 Hz, ipso], 125.4
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1
1
ppm [qd, J(CF) = 317.8 Hz, J(PC) = 56.6 Hz], 128.6 ppm [d,
J(PC) = 10.9 Hz], 132.0 ppm [d, J(PC) = 2.1 Hz], 133.5 ppm [d,
J(PC) = 16.3 Hz].
16 P. D. Cookson and E. R. T. Tiekink, Acta Crystallogr., Sect. C: Cryst.
Struct. Commun., 1993, 49, 1602.
17 K. Angermaier, E. Zeller and H. Schmidbaur, J. Organomet. Chem.,
1994, 472, 371.
18 N. C. Baenziger, W. E. Bennett and D. M. Soboroff, Acta Crystallogr.,
Sect. B: Struct. Crystallogr. Cryst. Chem., 1976, 32, 962.
19 K. Nunokawa, S. Onaka, T. Tatematsu, M. Ito and J. Sakai, Inorg.
Chim. Acta, 2001, 322, 56.
20 I. Dance and M. Scudder, J. Chem. Soc., Chem. Commun., 1995, 1039.
21 R. C. Bott, P. C. Healey and G. Smith, Aust. J. Chem., 2004, 57, 213.
22 P. D. Cookson and E. R. T. Tiekink, Acta Crystallogr., Sect. C: Cryst.
Struct. Commun., 1994, 50, 1896.
23 U. Monkowius, S. Nogai and H. Schmidbaur, Organometallics, 2003,
22, 145.
24 M. Bardaj´ı, P. G. Jones and A. Laguna, J. Chem. Soc., Dalton Trans.,
2002, 3624.
[AuCl(PPh2(CF(CF3)2)], 8. Yield: 58%. White solid. Calcu-
lated for C15H10F7PClAu: C 30.69, H 1.72, P 5.28. Found C 29.96,
1
H 1.63, P 5.25. 31P{ H} NMR (CDCl3): d 37.3 ppm (m); 19F
3
3
NMR (CDCl3): d -67.4 ppm [dd, J(FF) = 8.6 Hz, J(PF) = 8.6
Hz], -180.9 [br d, 2J(PF) = 40 Hz]; 1H NMR (CDCl3): d 8.04 [dd,
J = 14.0, 7.5 Hz, 4H], 7.56–7.62 ppm [m, 2H], 7.47–7.52 [m, 4H].
[AuCl(PPh2CF(CF3)(C2F5))], 9. Yield: 47%. White solid. Cal-
culated for C16H10F9PClAu: C 30.17, H 1.58, P 4.87. Found: C 31.4
1
H 1.69, P 5.23. 31P{ H} NMR (CDCl3): 39.9 ppm [m]; 19F NMR
25 G. Jia, R. J. Puddephatt and J. J. Vittal, J. Organomet. Chem., 1993,
(CDCl3): -65.7 ppm [m, 3F], -79.9 [m, 3F], -107.3 ppm [dddm,
2J(FF) = 297.8 Hz, J = 33.1 Hz, 10.3 Hz, 1F], -111.6 ppm [dm,
2J(FF) = 297.8 Hz, 1F], -179.8 ppm [m, 1F]; 1H NMR (CDCl3):
8.02–8.10 ppm [m, 4H], 7.56–7.60 ppm [m, 2H], 7.46–7.52 ppm
[m, 4H].
449, 211.
26 M. J. Katz, K. Sakai and D. B. Leznoff, Chem. Soc. Rev., 2008, 37,
1884.
27 E. R. T. Tiekink and J.-G. Kang, Coord. Chem. Rev., 2009, 253, 1627.
28 N. A. Barnes, K. R. Flower, S. A. Fyyaz, S. M. Godfrey, A. T. McGown,
P. J. Miles, R. G. Pritchard and J. E. Warren, CrystEngComm, 2010, 12,
784.
29 K. K. Banger, R. P. Banham, A. K. Brisdon, W. I. Cross, G. Damant, S.
Parsons, R. G. Pritchard and A. Sousa-Pedares, J. Chem. Soc., Dalton
Trans., 1999, 427.
30 P. G. Jones and E. Bembenek, Acta Crystallogr., Sect. C: Cryst. Struct.
Commun., 1996, 52, 2396.
31 P. G. Jones and C. Thone, Acta Crystallogr., Sect. C: Cryst. Struct.
Commun., 1997, 53, 42.
32 Y. Dienes, U. Englert and T. Baumgartner, Z. Anorg. Allg. Chem., 2009,
635, 238.
Acknowledgements
We thank Ineos Fluor for providing samples of HFC-134a and
HFC-133a, Honeywell for a sample of HFC-225fa and Johnson
Matthey for the loan of sodium tetrachloroaurate. We wish to
acknowledge the use of the EPSRC’s Chemical Database Service
at Daresbury. We thank Dr Kevin Flower, a friend and valued
colleague, for helpful discussions.
33 H. W. Chen and E. R. T. Tiekink, Acta Crystallogr., Sect. E: Struct.
Rep. Online, 2003, 59, m50.
34 Y. Lin, P. G. Jones, R. Schmutzler and G. M. Sheldrick, Eur. J. Solid.
State Inorg. Chem., 1992, 29, 887.
35 (a) N. A. Barnes, A. K. Brisdon, F. R. W. Brown, C. J. Herbert, R. G.
Pritchard and G. Sadiq, Dalton Trans., 2008, 101; (b) N. A. Barnes, A.
K. Brisdon, C. Fish, J. V. Morey, R. G. Pritchard and J. E. Warren, J.
Fluorine Chem., 2010, 31, 1156.
36 N. A. Barnes, A. K. Brisdon, F. R. W. Brown, I. R. Crossley, C. Fish, J.
V. Morey, R. G. Pritchard and L. Sekhri, New J. Chem., 2004, 28, 828.
37 N. A. Barnes, A. K. Brisdon, M. J. Ellis and R. G. Pritchard, J. Fluorine
Chem., 2001, 112, 35.
38 A. K. Brisdon and I. R. Crossley, Chem. Commun., 2002, 2420.
39 M. B. Murphy-Jolly, L. C. Lewis and A. J. M. Caffyn, Chem. Commun.,
2005, 4479.
References
1 See for example M. J. McKeage, L. Maharaj and S. J. Berners-Price,
Coord. Chem. Rev., 2002, 232, 127and references therein.
2 See for example L. J. Larson, E. M. McCauley, B. Weissbart and D. S.
Tinti, J. Phys. Chem., 1995, 99, 7218; B. Weissbart, D. V. Toronto, A.
L. Balch and D. S. Tinti, Inorg. Chem., 1996, 35, 2490; Z. Assefa, B. G.
McBurnett, R. J. Staples, J. P. Fackler, B. Assmann, K. Angermaier and
H. Schmidbaur, Inorg. Chem., 1995, 34, 75; Z. Assefa, B. G. McBurnett,
R. J. Staples and J. P. Fackler, Inorg. Chem., 1995, 34, 4965.
3 See for example E. Mizushima, K. Sato, T. Hayashi and M. Tanaka,
Angew. Chem., Int. Ed., 2002, 41, 4563.
4 S. S. Pathaneni and G. R. Desiraju, J. Chem. Soc., Dalton Trans., 1993,
319.
5 F. Scherbaum, A. Grohman, B. Huber, C. Kru¨ger and H. Schmidbaur,
Angew. Chem., Int. Ed. Engl., 1988, 27, 1544; H. Schmidbaur, Gold
Bull., 1990, 23, 11; H. Schmidbaur, Chem. Soc. Rev., 1995, 24, 391; H.
Schmidbaur, Nature, 2001, 413, 31.
40 A. K. Brisdon and C. J. Herbert, Chem. Commun., 2009, 6658.
41 J. A. Muir, M. M. Muir, L. B. Pulgar, P. G. Jones and G. M. Sheldrick,
Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1985, 41, 1174.
42 E. R. T. Tiekink, Acta Crystallogr., Sect. C: Cryst. Struct. Commun.,
1989, 45, 1233.
43 P. B. Hitchcock and P. L. Pye, J. Chem. Soc., Dalton Trans., 1977,
6 P. Pyykko¨, Chem. Rev., 1997, 97, 597.
7 P. Pyykko¨, Angew. Chem., Int. Ed., 2004, 43, 4412.
1457.
44 C. E. Strasser, S. Cronje, H. Schmidbaur and H. G. Raubenheimer, J.
Organomet. Chem., 2006, 691, 4788.
45 M. A. A. Beg and H. C. Clark, Can. J. Chem., 1962, 40, 283.
46 C. A. Tolman, Chem. Rev., 1977, 77, 313.
47 B. J. Dunne, R. B. Morris and A. G. Orpen, J. Chem. Soc., Dalton
Trans., 1991, 653.
48 L. C. Lewis-Alleyne, M. B. Murphy-Jolly, X. F. Le, Goff and A. J. M.
Caffyn, Dalton Trans., 2010, 39, 1198.
8 P. Pyykko¨ and Y. Zhao, Angew. Chem., Int. Ed. Engl., 1991, 30, 604.
9 P. Pyykko¨, J. Li and N. Runeberg, Chem. Phys. Lett., 1994, 218, 133.
10 P. Pyykko¨, N. Runeburg and F. Mendizabal, Chem.–Eur. J., 1997, 3,
1451.
11 P. Pyykko¨ and F. Mendizabal, Chem.–Eur. J., 1997, 3, 1458.
12 P. Pyykko¨, W. Schneider, A. Bauer, A. Bayler and H. Schmidbaur,
Chem. Commun., 1997, 1111.
13 S-G Wang and W. H. E. Schwarz, J. Am. Chem. Soc., 2004, 126, 1266.
14 H. Schmidbaur, W. Graf and G. Mu¨ller, Angew. Chem., Int. Ed.
Engl., 1988, 27, 417; H. Schmidbaur, K. Dziwok, A. Grohmann and
G. Mu¨ller, Chem. Ber., 1989, 122, 893; K. Dziwok, J. Lachmann,
D. L. Wilkinson and G. Mu¨ller, Chem. Ber., 1990, 123, 423; R.
Narayanaswamy, M. A. Young, E. Parkhurst, M. Ouellette, M. E.
Kerr, D. M. Ho, R. C. Elder, A. E. Bruce and M. R. M. Bruce, Inorg.
Chem., 1993, 32, 2506; D. E. Harwell, M. D. Mortimer, C. B. Knobler,
F. A. Anet and M. F. Hawthorne, J. Am. Chem. Soc., 1996, 118, 2679.
15 D. V. Toronto, B. Weissbart, D. S. Tinti and A. L. Balch, Inorg. Chem.,
1996, 35, 2484.
49 C. J. Herbert, PhD thesis, University of Manchester, 2010.
50 N. A. Barnes, K. R. Flower, S. M. Godfrey, P. A. Hurst, R. Z. Khan
and R. G. Pritchard, CrystEngComm, 2010, 10, 4240.
51 G. M. Sheldrick, SHELXTL, Siemans Analytical X-ray instruments,
Madison, WI, 1995.
52 G. M. Sheldrick, SHELX-97, Institut fur Anorganische Chemie der
Universitat Go¨ttingen, Go¨ttingen, Germany, 1998.
53 A. L. Spek, PLATON, A Multipurpose Crystallographic Tool, Utrecht
University, Utreht, The Netherlands, 2005.
54 G. Ferguson, A. J. Lough and C. Glidewell, J. Chem. Soc. Perkin Trans.
2, 1989, 1685.
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