Gold(I) complexes bearing mixed-donor ligands derived from N-heterocyclic carbenes

Article abstract of DOI:10.1039/c0dt01613f

The new 2-phenylthiocarbamoyl-1,3-dimesitylimidazolium inner salt (IMes·CSNPh) reacts with [AuCl(L)] in the presence of NH ₄PF₆ to yield [(L)Au(SCNPh·IMes)]⁺ (L = PMe₃, PPh₃, PCy₃, CNBu

Full text of DOI:10.1039/c0dt01613f

View Article Online / Journal Homepage / Table of Contents for this issue
Dynamic Article Links
Dalton
Transactions
Cite this: Dalton Trans., 2011, 40, 6645
www.rsc.org/dalton
PAPER
Gold(I) complexes bearing mixed-donor ligands derived from N-heterocyclic
carbenes†
Eugene Y. Chia,a Saira Naeem,a Lionel Delaude,b Andrew J. P. Whitea and James D. E. T. Wilton-Ely*a
Received 19th November 2010, Accepted 12th January 2011
DOI: 10.1039/c0dt01613f
The new 2-phenylthiocarbamoyl-1,3-dimesitylimidazolium inner salt (IMes·CSNPh) reacts with
[AuCl(L)] in the presence of NH4PF6 to yield [(L)Au(SCNPh·IMes)]+ (L = PMe3, PPh3, PCy3, CNBut).
The carbene-containing precursor [(IDip)AuCl] reacts with IMes·CSNPh under the same conditions to
afford the complex [(IDip)Au(SCNPh·IMes)]+ (IDip = 1,3-bis(2,6-diisopropylphenyl)imidazol-
2-ylidene). Treatment of the diphosphine complex [(dppm)(AuCl)2] with one equivalent of
IMes·CSNPh yields the digold metallacycle, [(dppm)Au2(SCNPh·IMes)]2+, while reaction of
[L2(AuCl)2] with two equivalents of IMes·CSNPh results in [(L2){Au(SCNPh·IMes)}2]2+ (L2 = dppb,
dppf, or dppa; dppb = 1,4-bis(diphenylphosphino)butane, dppf =
1,1¢-bis(diphenylphosphino)ferrocene, dppa = 1,4-bis(diphenylphosphino)acetylene). The homoleptic
complex [Au(SCNPh·IMes)2]+ is formed on reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with
two equivalents of the imidazolium-2-phenylthiocarbamoyl ligand. This product reacts with AgOTf to
yield the mixed metal compound [AuAg(SCNPh·IMes)2]2+. Over time, the unusual trimetallic complex
[Au(AgOTf)2(SCNPh·IMes)2]+ is formed. The sulfur-oxygen mixed-donor ligands IMes·COS and
SIMes·COS (SIMes = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene) were used to prepare
[(L)Au(SOC·IMes)]+ and [(L)Au(SOC·SIMes)]+ from [(L)AuCl] (L = PPh3, CNtBu). The bimetallic
examples [(dppf){Au(SOC·IMes)}2]2+ and [(dppf){Au(SOC·SIMes)}2]2+ were synthesized from the
reaction of [(dppf)(AuCl)2] with the appropriate ligand. Reaction of [(tht)AuCl] with one equivalent of
IMes·COS or SIMes·COS yields [Au(SOC·IMes)2]+ and [Au(SOC·SIMes)2]+, respectively. The
compounds [(Ph3P)Au(SCNPh·IMes)]PF6, [(Cy3P)Au(SCNPh·IMes)]PF6 and
[Au(AgOTf)2(SCNPh·IMes)2]OTf were characterized crystallographically.
since the first representatives of this family were isolated and
Introduction
characterized in the late 1980s.4
Over the past twenty years, N-heterocyclic carbenes (NHCs) have
become firmly established as electron-rich and versatile donor
Perhaps the most notable examples of complexes with NHCs
employed as ancillary ligands are the Grubbs-type second-
ligands for transition metals.1 They have challenged or replaced
generation ruthenium–alkylidene catalysts for olefin metathesis
(Fig. 1).5 NHCs have also been applied to gold(I) chemistry,6
first by Burini7 and then by Raubenheimer and co-workers,8 who
pioneered the synthesis of gold–NHC complexes. The straightfor-
ward preparation of [(NHC)AuCl] derivatives devised by Nolan
and co-workers further contributed to the widespread use of these
compounds in organometallic catalysis.9 In addition to all of the
transition metals, NHCs form stable complexes with main group
elements, such as lithium or beryllium,10 as well as lanthanides
phosphines in many spheres due to their stronger s-donating
properties and potential for steric tuning.2 Thus far, research on
NHCs has mostly focused on derivatives of imidazole, triazole, or
thiazole, of which imidazol-2-ylidene and its saturated analogue
imidazolin-2-ylidene have been the subject of the most in-depth
studies.3 The potential for a wide variety of substituents on the
nitrogen atoms, including unsymmetrical combinations, helped
maintain the sustained interest in these divalent carbon species,
aDepartment of Chemistry, Imperial College London, South Kensington
Campus, London, UK, SW7 2AZ. E-mail: j.wilton-ely@imperial.ac.uk
bLaboratory of Macromolecular Chemistry and Organic Catalysis, Institut
de Chimie (B6a), Universite´ de Lie`ge, Sart-Tilman par 4000 Lie`ge, Belgium
† Electronic supplementary information (ESI) available: Crystallographic
data and anisotropic displacement ellipsoid plots for the structures of
2, 3 and 13. CCDC reference numbers 773283, 773284 and 784174. For
ESI and crystallographic data in CIF or other electronic format see DOI:
10.1039/c0dt01613f
Fig. 1 Notable examples of complexes bearing NHC ligands.
Dalton Trans., 2011, 40, 6645–6658 | 6645
This journal is
The Royal Society of Chemistry 2011
©

View Article Online
and actinides.11 They have also found applications on their own as
nucleophilic reagents and organocatalysts.12
which gave a molecular ion at m/z 440, and good agreement of
elemental analysis with calculated values.
Despite their high profile, NHCs have scarcely been used as
starting materials for the synthesis of other ligands. Upon reaction
with carbon dioxide, they form inner salts, which can be stored
and handled with no particular precautions.13 Such NHC·CO2
zwitterions are rather labile in solution and may be used as sur-
rogates to free carbenes for organometallic synthesis and catalytic
applications.14 Betaines are also obtained when carbon disulfide
reacts with NHCs or precursors thereof.15 The NHC·CS2 adducts
differ from the NHC·CO2 series in that the dithiocarboxylate
moiety shows no significant lability upon reaction with metals.16
The coordination chemistry of these stable zwitterions remained
almost unexplored17 previous to recent work based on ruthenium–
arene18 or vinyl complexes.19 These latter reports built on a
contemporary study of five imidazol(in)ium-2-dithiocarboxylates,
whose stereoelectronic properties were thoroughly investigated.20
Recently we have extended the study of this ligand set to the
synthesis of gold(I) complexes and gold nanoparticles,21 as part
of a program to explore multimetallic compounds and the surface
functionalisation of nanoparticles.22
Our interest in mixed-donor ligands23 led us to examine a
similarly underused class of zwitterions of the type NHC·CSNR,
obtained by reaction of NHCs with aryl isothiocyanates.16,24
The asymmetry and the choice of donor atom introduce op-
tions lacking in the NHC·CS2 ligands, as well as an addi-
tional site of steric modification on the nitrogen donor. In this
contribution, we investigate the coordination chemistry of the
new 2-phenylthiocarbamoyl-1,3-dimesitylimidazolium inner salt
(IMes·CSNPh) with various gold(I) precursors. We also report the
first gold(I) complexes of the O,S-mixed-donor ligands, IMes·COS
and SIMes·COS, formed upon treatment of the corresponding free
NHCs with carbon oxysulfide.
A dichloromethane solution of the archetypal gold(I) phosphine
complex, [AuCl(PPh3)], was treated with a small excess of the
IMes·CSNPh ligand (1) in the presence of ammonium hexafluo-
rophosphate in methanol for 1 h at room temperature (Scheme
1). After work up, a light yellow crystalline solid was obtained in
61% yield. Only one phosphorus-containing product was detected
1
by 31P NMR spectroscopy (singlet at 37.3 ppm). The H NMR
spectrum of complex 2 showed two closely spaced resonances at
2.32 and 2.35 ppm for the mesityl aliphatic protons, while the
NPh protons resonated between 6.16 and 6.84 ppm with the ortho
component showing the greatest shift with respect to the value
recorded for the free ligand. This is not surprising given that the
NPh protons are closest to the AuPPh3 unit, the coordination of
which also results in an increase in N–C double bond character.
The meta protons of the mesityl groups were observed at 7.05
ppm, slightly upfield of the imidazole HC CH protons at
8.19 ppm, which showed the largest shift compared to the free
ligand. 13C NMR data were recorded for 2, including an HSQC
(Heteronuclear Single Quantum Coherence) experiment. Themost
deshielded signal at 153.4 ppm was assigned to the imidazolium
C2 carbon, while the CSN carbon at 145.1 ppm resonated as a
doublet due to a 4.1 Hz coupling with the phosphorus nucleus. The
overall chemical composition of [(Ph3P)Au(SCNPh·IMes)]PF6 (2)
was corroborated by ESI-MS, which gave an abundant molecular
ion at m/z 898, as well as good agreement of elemental analysis
with calculated values. Single crystals of 2 were grown by vapour
diffusion of diethyl ether into a dichloromethane solution of
the complex. A suitable crystal was chosen for X-ray diffraction
analysis (Fig. 2). The results of this study are discussed below (see
Structural discussion).
Results and discussion
Complexes with a sulfur-nitrogen mixed-donor ligand
The ligand used in this study is the 1,3-bis(2,4,6-trimethylphenyl)-
2-N-phenylthiocarbamoyl imidazolium inner salt, IMes·CSNPh
(1). Although a number of NHC·CSNR zwitterions are known
in the literature,16,24 this particular compound had not been
described. It was isolated in 81% yield using a one-pot procedure
involving deprotonation of 1,3-dimesitylimidazolium chloride
(IMes·HCl) with sodium hydride to generate the corresponding
free imidazol-2-ylidene carbene in situ, followed by reaction
with phenyl isothiocyanate. Somewhat surprisingly, this betaine
was unstable in deuterated chloroform, so 1H NMR analysis
was carried out in acetone-d6 or CD2Cl2. Seven distinct proton
environments were observed with the mesityl methyl substituents
resonating at ca. 2.35 and 2.39 ppm in a 1 : 2 ratio. This observation
suggests that the protons of the ortho-methyl groups are rendered
equivalent on the NMR timescale. In acetone-d6, the N-phenyl
protons gave rise to a triplet at 6.79 ppm, a doublet at 6.89 ppm,
and a triplet in the 7.03–7.07 ppm region, overlapping with a
sharp singlet assigned to the meta-C6H2 protons at 7.05 ppm. The
deshielded imidazole HC CH protons were observed as a sharp
singlet at 7.66 ppm. Further evidence for the composition of the
ligand was provided by electrospray mass spectrometry (ESI-MS),
Fig.
2
Molecular structure of the cation in 2. Selected bond
◦
˚
lengths (A) and angles ( ): Au–P(41) 2.2670(4), Au–S(1) 2.3021(4),
S(1)–C(2) 1.7423(15), C(2)–C(4) 1.489(2), C(2)–N(3) 1.2659(19),
C(4)–N(5) 1.3357(19), C(4)–N(8) 1.3452(19); P(41)–Au–S(1) 167.432(14),
C(2)–S(1)–Au 112.15(5). Hydrogen atoms and the hexafluorophosphate
counteranion were omitted for clarity.
6646 | Dalton Trans., 2011, 40, 6645–6658
This journal is
The Royal Society of Chemistry 2011
©

View Article Online
Scheme 1 Preparation of gold(I)–(2-N-phenylthiocarbamoyl-1,3-dimesitylimidazolium) complexes 2–12.
Substantial steric effects are expected within complexes of
generic formula [(L)Au(SCNPh·IMes)]+ given the proximity of the
thiocarbamoyl ligand NPh moiety to the gold(I) centre. The greater
steric encumbrance introduced by the tricyclohexylphosphine
ligand compared to triphenylphosphine was investigated using the
complex [AuCl(PCy3)] as starting material instead of [AuCl(PPh3)]
(Scheme 1). The colourless product obtained was formulated as
[(Cy3P)Au(SCNPh·IMes)]PF6 (3) on the basis of a new singlet
at 58.6 ppm in the 31P NMR spectrum and multiplets between
was prepared in the same manner (Scheme 1). Spectroscopic data
due to the IMes·CSNPh ligand were similar to those found for 2
and 3, whereas the retention of the PMe3 ligand was confirmed by
the presence of a doublet at 1.37 ppm in the 1H NMR spectrum,
showing coupling of 11.5 Hz to the phosphorus nucleus.
In order to extend our investigations of the gold(I) fragments
beyond gold–phosphine units, the tert-butyl isocyanide precursor
[AuCl(CNtBu)] was treated with IMes·CSNPh in the presence of
NH4PF6 to provide [(tBuNC)Au(SCNPh·IMes)]PF6 (5) in moder-
ate yield (Scheme 1). The CNtBu substituent exerts a low steric
demand and has been used previously to form thiolate complexes
possessing distinctive solid-state structures.25 The presence of the
tBu substituent in the complex was confirmed by a sharp singlet
at 1.58 ppm due to its nine equivalent protons.
1
1.20 and 1.84 ppm in H NMR spectroscopy attributed to the
phosphine ligand. A molecular ion at m/z 916 was observed in
100% abundance. Single crystals of this product were obtained
(Fig. 3) and a structural study undertaken (vide infra). The
trimethylphosphine analogue, [(Me3P)Au(SCNPh·IMes)]PF6 (4),
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 6645–6658 | 6647
©

View Article Online
of only one phosphorus environment. Fast atom bombardment
(FAB) mass spectrometry revealed a molecular ion at m/z 1844.
Elemental analysis supported the proposed composition.
A
less usual diphosphine variant is found in the
1,2-bis(diphenylphosphino)acetylene complex, [(dppa)(AuCl)2],
which exhibits a rigid, linear configuration within the Ph2P–
C
C–PPh2 unit.31 This starting material was used to synthesize
[(dppa){Au(SCNPh·IMes)}2](PF6)2 (8) (Scheme 1). The 31P NMR
spectrum of the product showed a single resonance at 9.1 ppm.
The twenty protons from the four phenyl groups gave rise to a
broad multiplet between 7.63 and 7.65 ppm in the 1H NMR
spectrum, while FAB-MS analysis revealed a molecular ion at
m/z 1812. A further metal centre was introduced into this type
of assembly through the use of [(dppf)(AuCl)2] as a precursor to
[(dppf){Au(SCNPh·IMes)}2](PF6)2 (9), which exhibited two broad
singlets at 3.97 and 4.45 ppm in 1H NMR spectroscopy. The
flexibility of the dppf unit could in theory allow a metallacycle
to form.32 However, reaction with one or two equivalents of
IMes·CSNPh resulted in 9, which displayed spectroscopic features
consistent with the coordination of two IMes·CSNPh units
(no change in the chemical shift of the NPh protons). This
stoichiometry was further supported by FAB mass spectrometry
and elemental analysis.
˚
Fig. 3 Molecular structure of the cation in 3. Selected bond lengths (A)
and angles (◦): Au–P(41) 2.2731(6), Au–S(1) 2.3084(6), S(1)–C(2) 1.748(3),
C(2)–C(4) 1.493(3), C(2)–N(3) 1.271(3), C(4)–N(5) 1.338 (3), C(4)–N(8)
1.331(3); P(41)–Au–S(1) 169.04(2), C(2)–S(1)–Au 107.71(8). Hydrogen
atoms and the hexafluorophosphate counteranion were omitted for clarity.
The reaction of [(dppm)(AuCl)2] with one equivalent of
IMes·CSNPh led to the formation of a light yellow solid
(Scheme 1). Integration of the triplet resonance observed
at 3.38 ppm (2JHP 11.8 Hz) for the methylene protons of
the dppm ligand indicated the formation of the metallacycle
[(dppm)Au2(SCNPh·IMes)](PF6)2 (10). Based on literature prece-
dent, it is likely that the close proximity of the gold centres in
10 permits aurophilic interactions to guide the formation of a
cyclic product, as found in many dithiocarbamate compounds
of the form [(dppm)Au2(S2CNR2)]+,30 or in the more closely
related compound [(dppm)Au2(S2C·IMes)](PF6)2.21 A second
route giving access to the bis(triflate) salt of 10 instead of the
bis(hexafluorophosphate) compound was also investigated (see
Experimental section). It involved removal of the chloride ligands
in [(dppm)(AuCl)2] by AgOTf and yielded a product of greater
purity.
As mentioned above (cf. Fig. 1), NHC ligands have entered the
arena of gold(I) chemistry, challenging the ubiquity of [AuCl(PR3)]
complexes. The compound [AuCl(IDip)], featuring the 1,3-bis(2,6-
diisopropylphenyl)imidazol-2-ylidene ligand, was used to prepare
[(IDip)Au(SCNPh·IMes)]PF6 (6), again in moderate yield due to
partial solubility of the product in the ethanol used for work up
(Scheme 1). 1H NMR analysis of the product showed signals
arising from the IDip moiety in addition to those due to the
IMes·CSNPh ligand. Two sets of doublets at 1.14 and 1.16
ppm were observed for the isopropyl methyl protons, while the
adjacent methine unit gave a septet at 2.49 ppm. Both signals
3
show mutual coupling of JHH = 6.9 Hz. The overall chemical
composition of [(IDip)Au(SCNPh·IMes)]PF6 (6) was confirmed
by ESI-MS and good agreement of elemental analysis with
calculated values. Unfortunately, neither complex 5 nor 6 formed
crystals of sufficient quality for X-ray diffraction.
With many 1,1-dithio ligands, such as dithiocarbamate an-
ions, homoleptic, metallacyclic, digold complexes of generic
formula [Au2(S2CNR2)2] are commonly formed, typically with
a short separation of gold(I) centres.26,33 This trend was further
supported when [AuCl(tht)] (tht = tetrahydrothiophene) was
treated with the dithiocarboxylate betaine IMes·CS2, yielding
[Au2(S2C·IMes)2](PF6)2.21 In contrast, the reaction between the
same gold precursor and either one or two equivalents of
IMes·CSNPh (1) resulted in the formation of the monogold
species [Au(SCNPh·IMes)2](PF6) (11), in which the gold centre
bears a formal negative charge, thereby requiring only a single
hexafluorophosphate counteranion (Scheme 1). This formulation
was based on elemental analysis and mass spectrometry data, with
the latter displaying a 100% abundant molecular ion at m/z 1075.
Monovalent gold has a greater affinity for sulfur compared to
nitrogen, but the outcome was still surprising, given that many
cyclic species are known with similar mixed-donor ligands, such as
2-mercaptopyridine in [Au2(S,N-Spy)2].34 The steric demand of the
NPh groups might explain the different coordination behaviour
exhibited by 11. Indeed, the most significant chemical shift change
The next stage in our investigations was to explore the
synthesis of digold complexes with IMes·CSNPh (1). Previous
studies have shown that the length of the bridging hydrocarbon
chain in the diphosphine compounds [{Ph2P(CH2)nPPh2}(AuCl)2]
is often the source of their structural diversity in the solid
state.26 For longer hydrocarbon chain lengths, such as buty-
lene in [(dppb)(AuCl)2], intramolecular aurophilic interactions27
are not observed;28 whereas for a single methylene bridge in
[(dppm)(AuCl)2], ‘A-frame’ configurations with short contacts
between neighbouring gold(I) centres are favoured.29 For this
reason the dppm motif has been utilized in earlier work on dithio
ligands, e.g. [(dppm)Au2(S2CNR2)]+, to access metallacycles.30
The reaction of [(dppb)(AuCl)2] with two equivalents
of IMes·CSNPh in the presence of NH4PF6 yielded
[(dppb){Au(SCNPh·IMes)}2](PF6)2 (7) in 62% yield (Scheme 1).
The protons of the chelating diphosphine butylene bridge gave rise
1
to H NMR signals at 1.38 and 2.10 ppm corresponding to four
protons each as unresolved multiplets, while a single resonance
at 34.2 ppm in the 31P NMR spectrum confirmed the presence
6648 | Dalton Trans., 2011, 40, 6645–6658
This journal is
The Royal Society of Chemistry 2011
©

View Article Online
Scheme 2 Addition of silver triflate to gold(I)–(2-phenylthiocarbamoyl-1,3-dimesitylimidazolium) complex 11.
1
in H NMR spectroscopy was shown by the ortho-NPh protons,
structure are the presence of two silver units and the fact that
they are not associated with the nitrogen donors. The triflate ions
bridge the silver units, while the silver ions themselves occupy
a triangular arrangement with the gold centre and the sulfur
donors. The remaining crystals from those grown were collected
which resonated at 5.68 ppm in the complex compared to 6.89
ppm in the free ligand.
In order to ascertain whether or not coordination to the pendant
nitrogen donors in compound 11 was possible, this complex was
treated with one equivalent of AgOTf (Scheme 1 and 2). The
1H NMR spectrum of the product exhibited resonance patterns
similar to 11 with some significant changes in their chemical shifts.
All five protons of the N-phenyl substituent were shifted downfield
(consistent with deshielding due to the effect of coordination),
with the largest displacements (+0.2 ppm) being observed for
the para and meta protons to 6.98 and 7.12 ppm, respectively.
There was also a significant change in the resonance attributed
to the imidazole HC CH protons from 7.37 to 7.62 ppm. Mass
spectrometry (FAB) displayed a molecular ion at m/z 1183, as
well as signals for [M + OTf]+ at 1333 and [M - Ag]+ at 1075.
The overall composition was further supported by elemental
analysis data to be [AuAg(SCNPh·IMes)2](PF6)(OTf) (12). The
formulation shown in Scheme 1 is the most likely one in terms of
bonding mode for the silver ion (the triflate may or may not be
coordinating).
1
and analyzed by mass spectrometry and H NMR spectroscopy.
In the former case, a molecular ion for the AuAg2 assembly was
observed at m/z 1589, as well as loss of a triflate anion at m/z
1
1333. The H NMR spectrum obtained, on the other hand, was
identical to that recorded for 12. It is probable that the structure
of 13 is not retained in solution and that one silver triflate unit
dissociates to reform 12. The structure of 13 raises the possibility
that the AgOTf unit in 12 may be coordinated to one sulfur rather
than to both nitrogen donors, however, this is undermined by the
simplicity of the 1H NMR spectrum, in which no inequivalence is
observed for the IMes·CSNPh resonances. Attempts to obtain 13
on a preparative scale remained unsuccessful. Addition of excess
AgOTf to 11 only yielded 12 and no further reaction was observed.
Complexes with sulfur-oxygen mixed-donor ligands
Laguna and co-workers have investigated the contacts formed
between gold(I) centres and other metals (particularly those of
groups 11–13), revealing some fascinating motifs in the solid
state.35 Attempts to grow crystals of 12 in order to determine
unambiguously its structure were frustrated continually by poor
crystal quality or unsuitable morphology (very thin needles).
Eventually, leaving a solution of the complex in dichloromethane
layered with diethyl ether over a period of a week yielded a signif-
icant number of crystals of the same type. One of them was used
for X-ray diffraction analysis. However, the molecular structure
obtained did not belong to the expected complex 12, but rather to
a new trimetallic species, [Au(AgOTf)2(SCNPh·IMes)2]OTf (13),
bearing two silver triflate units bonded to the gold and sulfur
atoms (Scheme 2 and Fig. 4). The most surprising features of this
Although the reactions of NHCs with CO2 and CS2 are well
documented,16 no reports exist of the formation of zwitterions
with COS. However, exploratory work indicated that the thiocar-
boxylate betaines display a stability intermediate between those of
the NHC·CO2 and NHC·CS2 adducts when used as mixed-donor
ligands for ruthenium(II) complexes.36 These results prompted us
to examine the coordination chemistry of gold(I) with two rep-
resentative NHC·COS inner salts, viz., 1,3-dimesitylimidazolium-
2-thiocarboxylate (IMes·COS) and its saturated heterocycle ana-
logue SIMes·COS.
Treatment of [AuCl(PPh3)] with IMes·COS resulted in a pale
yellow product, which was analyzed by multinuclear NMR
spectroscopy to be the new compound [(Ph3P)Au(SOC·IMes)]PF6
(14) (Scheme 3). Only one singlet appeared at 37.8 ppm in 31P
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 6645–6658 | 6649
©

View Article Online
◦
˚
Fig. 4 Molecular structure of the C2-symmetric cation in 13. Selected bond lengths (A) and angles ( ): Au(1)–S(1) 2.3095(13), S(1)–C(2) 1.755(6),
C(2)–N(3) 1.276(7), C(2)–C(4) 1.496(7), S(1)–Au(1)–S(1A) 173.92(7). Hydrogen atoms and the trifluoromethanesulfonate counteranion were omitted for
clarity.
1
NMR spectroscopy, while the H NMR spectrum of compound
14 displayed signals at similar chemical shift values to those
observed in 2 minus the aromatic signals due to the NPh group.
The overall chemical composition was supported by electrospray
mass spectrometry (+ve mode), which showed a 100% abundance
for the molecular ion at m/z 823, together with good agreement
of elemental analysis with calculated values. The analogous
compound [(Ph3P)Au(SOC·SIMes)]PF6 (15) was formed in a
similar manner from [AuCl(PPh3)] and SIMes·COS (Scheme 3).
Spectroscopic data were found to be almost identical, apart from
the NHC·COS ligands themselves resulted in reduced yields.36
However, from spectroscopic investigations, complexes 14 and 15
did not appear to be unstable once isolated.
In order to explore the range of co-ligands supported by
the NHC·COS units, the isocyanide compound [(tBuNC)AuCl]
was treated with IMes·COS and SIMes·COS to yield the
colourless complexes [(tBuNC)Au(SOC·IMes)]PF6 (16) and
[(tBuNC)Au(SOC·SIMes)]PF6 (17), respectively (Scheme 3). In
addition to typical resonances for the methyl protons of the mesityl
groups, a new singlet was observed at 1.63 ppm in both 16 and 17,
which was attributed to the tertiary butyl unit. The presence of the
isocyanide ligand was also apparent in the solid-state infrared
spectrum with strong absorptions at 2240 (16) and 2239 (17)
cm-1. The overall formulation was supported by molecular ions in
the mass spectra and good agreement of elemental analysis with
calculated values. Unfortunately, no crystals could be obtained
to ascertain the solid-state implications of the slim steric profile
conferred by the isocyanide ligand.
1
the resonance at 4.72 ppm in the H NMR spectrum due to the
four ethylene protons of the SIMes ligand heterocyclic backbone.
Again, the overall chemical composition was confirmed by mass
spectrometry and elemental analysis. Unsatisfactory yields were
partly due to significant electrostatic behaviour, which prevented
all the solids being transferred successfully from the filtration
apparatus. In addition, the yield from the actual reactions was
also low and this could be due to partial loss of gaseous COS in a
similar manner to that observed for elimination of carbon dioxide
from NHC·CO2 adducts in solution. Indeed, recrystallisation of
In a similar manner to the synthesis of 9, [dppf(AuCl)2] was
treated with two equivalents of either IMes·COS or SIMes·COS
6650 | Dalton Trans., 2011, 40, 6645–6658
This journal is
The Royal Society of Chemistry 2011
©

View Article Online
Scheme 3 Preparation of gold(I)–(1,3-dimesitylimidazol(in)ium-2-thiocarboxylate) complexes. Monometallic complexes: NHC·COS = IMes·COS, L =
PPh3 (14), CNBut (16); NHC·COS = SIMes·COS, L = PPh3 (15), CNBut (17). Bimetallic complexes: IMes·COS (18), SIMes·COS (19). Homoleptic
complexes: IMes·COS (20), SIMes·COS (21).
˚
similar and longer than that of 2.2447(10) A reported for the
to provide the complexes [(dppf){Au(SOC·IMes)}2](PF6)2
(18) and [(dppf){Au(SOC·SIMes)}2](PF6)2 (19), respectively
(Scheme 3). The retention of the ferrocenyl unit was indicated
by broad resonances at 3.89 and 4.13 ppm (for 18), while typical
features were observed for the NHC·COS ligands. Again the
overall composition was confirmed by mass spectrometry and
elemental analysis.
piperidine dithiocarbamate complex [(Ph3P)Au(S2CNC4H8)].38
The Au–S distance of 2.3021(4) in 2 is shorter than that found in ei-
ther the IMes·CS2 analogue [2.3223(7) A]21 or the dithiocarbamate
˚
complex [2.3344(11) A]. With a value of 169.04(2)◦, the P–Au–
38
˚
S linkage in [(Cy3P)Au(SCNPh·IMes)]PF6 (3) is approximately
linear (see Fig. 3), though the angle is again clearly influenced by
the steric requirements of the NPh unit. The Au–P distance of
2.2731(6) A in 3 is slightly longer than the corresponding distance
of 2.2670(4) A found in 2, while the Au–S distances are similar in
Given that the betaines IMes·CS2 and IMes·CSNPh reacted
˚
very differently with [ClAu(tht)] to yield either the digold cyclic
21
˚
compound [Au2(S2C·IMes)2](PF6)2 or the monogold complex
both structures.
[Au(SCNPh·IMes)2](PF6) (11), the products from the correspond-
ing reactions with IMes·COS and SIMes·COS were investigated
(Scheme 3). While characteristic resonances of the thiocarboxylate
ligands were observed in the 1H NMR spectra, this did not
provide any evidence beyond that of successful reaction to give
the homoleptic complexes. However, the mass spectra (FAB
positive mode) of the compounds revealed molecular ions at
m/z 925 and m/z 929 for [Au(SOC·IMes)2](PF6)2 (20) and
[Au(SOC·SIMes)2](PF6)2 (21), respectively. These monogold for-
mulations were supported by elemental analysis and are perhaps
unsurprising given the hard/soft mismatch between the gold(I)
centre and the oxygen donors. Indeed, very few compounds of
gold(I) bearing oxygen donors are known. To the best of our
knowledge, alkoxide analogues of [(R3P)Au(SR)] are unknown
and examples of carboxylate analogues of [(R3P)Au(S2CR)] are
rare.37
Space-filling diagrams of complexes 2, 3 and the analogous
dithiocarboxylate derivative are shown in Fig. 5. They illustrate
the change in coordination environment of the gold centre caused
by replacing a sulfur atom in the 1,1-dithio ligand with an N-
phenyl substituent. One approach to the metal centre is rendered
inaccessible by the steric bulk of the aromatic ring, a feature
that could be exploited for catalytic purposes in the appropriate
setting. Comparison between Fig. 5b and 5c shows that the
greater steric requirement of tricyclohexylphosphine compared
to triphenylphosphine results in the gold centre being enclosed
even more substantially by the neighbouring atoms, allowing
access only from the exposed face shown in Fig. 5d. While these
complexes are not expected to show catalytic activity themselves,
these observations illustrate the potential for fine-tuning the access
to metal centres to which the ligand is attached through alteration
of the steric demands of the substituents.
The complex cation [Au(AgOTf)2(SCNPh·IMes)2]+ in 13 has C2
symmetry about an axis that passes through the gold centre and bi-
sects the Ag(1) ◊ ◊ ◊ Ag(1A) vector (see Fig. 4). The Ag(1) ◊ ◊ ◊ Ag(1A)
Structural discussion
The geometry at the gold centre in the structure of [(Ph3P)-
Au(SCNPh·IMes)]PF6 (2) is significantly bent with a P–Au–S
angle of 167.432(14)◦ (see Fig. 2). Compared to the 178.94(3)◦
value determined previously for [(Ph3P)Au(S2C·IMes)]PF6,21 the
deviation from linearity is more significant and can be traced to
the greater steric demand of the NPh unit. The Au–P distances of
˚
separation is 3.417(3) A. There is, however, significant disorder
in the Ag2(CF3SO3)2 unit, making the bond lengths and angles,
particularly those of the triflate ions, and even the conformations
of this area somewhat uncertain. The bond data relating to the
IMes·CSNPh ligand are comparable to those found in the struc-
2.2670(4) A in 2 and 2.2622(7) A in the literature compound,21 are
tures of 2 and 3, with the Au–S(1) distance of 2.3095(13) A being
˚
˚
˚
This journal is The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 6645–6658 | 6651
©

View Article Online
Fig. 5 Space-filling representations of a) [(Ph3P)Au(S2C·IMes)]PF6;21 b) [(Ph3P)Au(SCNPh·IMes)]PF6 (2); c) [(Cy3P)Au(SCNPh·IMes)]PF6 (3) with
phosphorus obscured; d) rotated view of [(Cy3P)Au(SCNPh·IMes)]PF6 (3).
close to the distance found in 3 but marginally longer than the
corresponding bond length in 2. The S(1)–Au–S(1A) angle is
almost linear at 173.92(7)◦. Most of the disorder is concentrated on
the triflate bridges, leaving the Ag(1)–S(1) distance of 2.5675(18)
as mixed-donor ligands. Like the related NHC·CS2 betaines,
their steric profile can be tailored through variation of the
imidazol(in)ium substituents, while additional control over the
coordination sphere of the metal can be exerted by the NR
unit in the case of the NHC·CSNR adducts. In some instances,
the reactivity of the N-phenylthiocarbamoyl and thiocarboxylate
inner salts reflected that of the dithiocarboxylate betaines but
in others, as in the case of the homoleptic compound (11), the
reaction took a different course. As a result, new coordination
behaviour was observed, allowing a further metal centre to
be incorporated into the system. Work is currently underway
to explore the hemilabile properties of the NHC·CSNPh and
NHC·COS ligands as bidentate chelates in catalysis.
˚
˚
A and the Ag(1A)–S(1A) length of 2.486(5) A as relatively
reliable. There are two Au(1)–Ag(1) distances corresponding to
˚
orientations of 77% occupancy [2.9064(12) A] and 23% occupancy
˚
[2.960(4) A]. These are well below the sum of the van der Waals
39
˚
radii for the elements (3.38 A). Although no directly analogous
structures have been reported, these distances may be com-
pared with some pertinent literature values. In the metallacyclic
diphenylpyridylphosphine complex [AuAg(PPh2py)(OClO3)2] re-
ported by Schmidbaur and co-workers,40 the Au–Ag distance is
˚
˚
2.820(1) A, while a longer distance of 2.9314(5) A is reported
in [AuAg(PPh2CH2SPh)2](OTf)2], which is also an 8-membered
cyclic species.41 The diphenylmethylenedithiophosphinate com-
plex [AuAg(CH2PPh2S)2] has the gold centres coordinated through
Experimental section
General comments. Unless otherwise stated, all experiments
were carried out under aerobic conditions and the complexes
obtained appear relatively stable towards the atmosphere, whether
in solution or in the solid state. Some decomposition to
gold colloid was occasionally observed, indicated by a purple
colouration. Reagents and solvents were used as received from
commercial sources. Petroleum ether is the fraction boiling
in the 40–60 ◦C range. The following complexes and ligands
were prepared as described elsewhere: [AuCl(PR3)], (R = Me,44
Cy,45 Ph29), [dppf(AuCl)2],46 [dppm(AuCl)2],47 [dppb(AuCl)2],28
[dppa(AuCl)2],29 [AuCl(tht)],48 [AuCl(IDip)],12 [AuCl(CNtBu)],49
IMes·HCl,50 IMes·COS,36 and SIMes·COS.36 Electrospray and
Fast Atom Bombardment (FAB) mass data were obtained using
carbon while the silver is bonded to the sulfur centres, resulting
42
˚
in a distance between the metals of 2.9124(13) A. Even in
non-metallacyclic systems, such as [Ag(m-dppm)2(AuMes)2]ClO4
(Mes = 2,4,6-trimethylphenyl), the Au–Ag distances are consid-
erably below the sum of the van der Waals radii [2.944(2) and
2.946(2) A].43 These short distances have been interpreted in terms
˚
of metallophilic interactions, the like of which are commonly
observed between gold(I) centres.35
Conclusion
The gold(I) complexes described in this report demonstrate
the great potential of NHC·CSNR and NHC·COS zwitterions
6652 | Dalton Trans., 2011, 40, 6645–6658
This journal is
The Royal Society of Chemistry 2011
©

View Article Online
Micromass LCT Premier and Autospec Q instruments, respec-
tively. Infrared data were obtained using a Perkin Elmer Paragon
1000 FT-IR spectrometer. NMR spectroscopy was performed at
25 ◦C using Varian Mercury 300 and Bruker AV400 spectrometers
in CDCl3 unless otherwise indicated. All coupling constants are
in Hertz. The 31P NMR spectra of all complexes exhibited a
septet resonance due to the hexafluorophosphate counteranion
at -144.3 ppm (JPF = 708 Hz). Elemental analysis data were
obtained from London Metropolitan University. The procedures
given provide materials of sufficient purity for synthetic and
spectroscopic purposes.
PPh3, JPC = 58.9 Hz), 129.5 (d, m-PPh3, JPC = 11.8 Hz), 129.8
(s, m-NPh), 130.0 (s, m-Mes), 131.0 (s, p-Mes), 132.4 (s, p-PPh3),
134.5 (d, o-PPh3, JPC = 13.8 Hz), 135.7 (s, o-Mes), 142.0 (s, ipso-
Mes), 145.1 (d, N C–S, JPC = 4.1 Hz), 149.8 (s, ipso-NPh), 153.4
(s, Im NCN) ppm. MS (ES +ve; abundance): m/z 898 (100) [M]+,
440 (18) [M - AuPPh3]+. Analysis: Calcd for C46H44AuF6N3P2S:
C, 52.9; H, 4.2; N, 4.0. Found: C, 53.0; H, 4.2; N, 3.9%.
[(Cy3P)Au(SCNPh·IMes)]PF6 (3). A dichloromethane solu-
tion (10 mL) of [AuCl(PCy3)] (42 mg, 0.083 mmol) was treated
with a solution of 1 (40 mg, 0.091 mmol) in dichloromethane
(10 mL). NH4PF6 (27 mg, 0.166 mmol) in methanol (10 mL)
was added and the light yellow reaction mixture was stirred for
1 h at room temperature. All the solvents were removed and
the crude product was dissolved in dichloromethane (10 mL).
The suspension was filtered through Celite to remove NH4Cl and
excess NH4PF6. Diethyl ether (20 mL) was added and the crude
solid triturated ultrasonically to give the product. The precipitate
was filtered, washed with diethyl ether (10 mL), petroleum ether
(10 mL) and dried to give a colourless solid (38 mg, 43%). IR
(neat): 2923, 2852, 1580, 1556, 1493, 1445, 1234, 1177, 918, 834
(nP–F), 771, 757, 741, 726, 695 cm-1. 31P NMR (acetone-d6): 58.6 (s,
IMes·CSNPh (1). All glassware for this reaction was oven-
dried before use. Phenyl isothiocyanate (0.481 g, 3.56 mmol)
and 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride (1.21 g,
3.56 mmol) were dissolved in anhydrous THF (30 mL). Sodium
hydride (0.214 g, 5.34 mmol, 60% dispersion in mineral oil)
was added in portions over 15 min to the mixture cooled at
10–15 ◦C under N2. The suspension was stirred at 10–15 ◦C for 18
h. It was then quenched by adding water (10 mL) dropwise, after
which all the solvents were removed. The residue was extracted
with dichloromethane (30 mL), dried over anhydrous MgSO4,
and the solvent removed to give the crude imidazolium inner
salt. Recrystallisation from dichloromethane and petroleum ether
yielded 1 as pale yellow powder (1.26 g, 81%). IR (neat): 3139,
2917, 1607, 1512, 1483, 1379, 1227, 1182, 1170, 1033, 1015, 957,
1
PCy3) ppm. H NMR (acetone-d6): 1.20–1.36 and 1.70–1.84 (m,
33H, Cy), 2.34 (s, 12H, o-CH3), 2.43 (s, 6H, p-CH3), 6.40 (d, 2H,
o-NPh, JHH = 8.3 Hz), 7.15 (t, 1H, p-NPh, JHH = 8.6 Hz), 7.21
(s, 4H, m-C6H2), 7.36 (t, 2H, m-NPh, JHH = 7.9 Hz), 8.14 (s, 2H,
HC CH) ppm. MS (ES +ve; abundance): m/z 916 (100) [M]+,
440 (45) [M - AuPCy3]+. Analysis: Calcd for C46H62AuF6N3P2S:
C, 52.0; H, 5.9; N, 4.0. Found: C, 52.0; H, 5.9; N, 3.9%.
1
853, 768 cm-1. H NMR (acetone-d6): 2.35 (s, 6H, p-CH3), 2.39
(s, 12H, o-CH3), 6.79 (t, 1H, p-NPh, JHH = 7.2 Hz), 6.89 (d, 2H,
o-NPh, JHH = 9.7 Hz), 7.03–7.07 (m, 2H + 4H, m-NPh + m-C6H2),
7.66 (s, 2H, HC CH) ppm. 1H NMR (CD2Cl2): 2.39 (s, 12H, o-
CH3), 2.41 (s, 6H, p-CH3), 6.60 (d, 2H, o-NPh, JHH = 7.2 Hz), 6.88
(t, 1H, p-NPh, JHH = 7.3 Hz), 7.09 (s, 4H, m-C6H2), 7.13 (t, 2H, m-
NPh, JHH unresolved), 7.15 (s, 2H, HC CH) ppm. MS (ES +ve;
abundance): m/z 440 (100) [M]+. Analysis: Calcd for C28H29N3S:
C, 76.5; H, 6.6; N, 9.6%. Found: C, 76.7; H, 6.5; N, 9.6%.
[(Me3P)Au(SCNPh·IMes)]PF6 (4). A dichloromethane solu-
tion (10 mL) of [AuCl(PMe3)] (30 mg, 0.097 mmol) was treated
with a solution of 1 (47 mg, 0.107 mmol) in dichloromethane
(10 mL). NH4PF6 (32 mg, 0.194 mmol) in methanol (10 mL)
was added and the light yellow reaction mixture was stirred for
1 h at room temperature. All the solvents were removed and the
crude product was dissolved in dichloromethane (10 mL). The
suspension was filtered through Celite to remove NH4Cl and excess
NH4PF6. Ethanol (15 mL) was added and the solvent volume
was reduced until precipitation of the product was complete. The
precipitate was filtered, washed with ethanol (10 mL), petroleum
ether (10 mL) and dried to give a light yellow solid (40 mg, 48%).
IR (neat): 1491, 1447, 1417, 1383, 1227, 1188, 1164, 1104, 955, 920,
831 (nP–F), 764 cm-1. 31P NMR (acetone-d6): -2.7 (s, PMe3) ppm.
1H NMR (acetone-d6): 1.37 (d, 9H, CH3, JHP = 11.5 Hz), 2.33
[(Ph3P)Au(SCNPh·IMes)]PF6 (2). A dichloromethane solu-
tion (10 mL) of [AuCl(PPh3)] (50 mg, 0.101 mmol) was treated
with a solution of 1 (67 mg, 0.151 mmol) in dichloromethane
(10 mL). NH4PF6 (33 mg, 0.202 mmol) in methanol (10 mL)
was added and the light yellow reaction mixture was stirred for
1 h at room temperature. All the solvents were removed and the
crude product was dissolved in dichloromethane (10 mL). The
suspension was filtered through Celite to remove NH4Cl and excess
NH4PF6. Ethanol (15 mL) was added and the solvent volume
was reduced until precipitation of the product was complete. The
product was filtered, washed with ethanol (10 mL), petroleum
ether (10 mL) and dried to give a light yellow crystalline solid
(66 mg, 62%). IR (neat): 3172, 1599, 1496, 1482, 1383, 1238, 1103,
1072, 1030, 999, 912, 832 (nP–F), 760 cm-1. 31P NMR (acetone-d6):
(s, 12H, o-CH3), 2.44 (s, 6H, p-CH3), 6.07 (d, 2H, o-NPh, JHH
=
11.5 Hz), 7.13 (t, 1H, p-NPh, JHH = 8.0 Hz), 7.24 (s, 4H, m-C6H2),
7.45 (t, 2H, m-NPh, JHH = 8.0 Hz), 8.17 (s, 2H, HC CH) ppm.
MS (ES +ve; abundance): m/z 712 (100) [M]+. Analysis: Calcd for
C31H38AuF6N3P2S: C, 43.4; H, 4.5; N, 4.9. Found: C, 43.5; H, 4.4;
N, 4.8%.
1
37.3 (s, PPh3) ppm. H NMR (acetone-d6): 2.32 (s, 6H, p-CH3),
2.35 (s, 12H, o-CH3), 6.16 (d, 2H, o-NPh, JHH = 7.3 Hz), 6.54
(t, 1H, p-NPh, JHH = 7.5 Hz), 6.84 (t, 2H, m-NPh, JHH = 7.5
Hz), 7.19 (s, 4H, m-C6H2), 7.27–7.69 (m, 15H, C6H5), 8.19 (s, 2H,
[(tBuNC)Au(SCNPh·IMes)]PF6 (5). A dichloromethane solu-
tion (10 mL) of [AuCl(CNtBu)] (26 mg, 0.083 mmol) was treated
with a solution of 1 (40 mg, 0.091 mmol) in dichloromethane
(10 mL). NH4PF6 (27 mg, 0.166 mmol) in methanol (10 mL)
was added and the light yellow reaction mixture was stirred for
1 h at room temperature. All the solvents were removed and
the crude product was dissolved in dichloromethane (10 mL).
The suspension was filtered through Celite to remove NH4Cl and
1
HC CH) ppm. H NMR (CD2Cl2): 2.30 (s, 12H, o-CH3), 2.37
(s, 6H, p-CH3), 6.09 (d, 2H, o-NPh, JHH = 7.2 Hz), 6.40 (t, 1H,
p-NPh, JHH = 7.5 Hz), 6.77 (t, 2H, m-NPh, JHH = 7.6 Hz), 7.11 (s,
4H, m-C6H2), 7.15–7.64 (m, 15H, C6H5), 7.53 (s, 2H, HC CH)
ppm. 13C NMR (CD2Cl2): 18.1 (s, o-CH3), 21.3 (s, p-CH3), 118.8
(s, o-NPh), 123.5 (s, HC CH), 125.0 (s, p-NPh), 128.7 (d, ipso-
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 6645–6658 | 6653
©

View Article Online
excess NH4PF6. Pentane (20 mL) was added and the crude solid
triturated ultrasonically to give the product. The precipitate was
filtered, washed with pentane (10 mL) and dried to give a light
yellow solid (34 mg, 48%). IR (neat): 3323, 2234 (nCN), 1588, 1557,
[(dppa){Au(SCNPh·IMes)2}](PF6)2 (8). A dichloromethane
solution (10 mL) of [(dppa)(AuCl)2] (35 mg, 0.041 mmol)
was treated with a solution of 1 (40 mg, 0.091 mmol) in
dichloromethane (10 mL). NH4PF6 (20 mg, 0.123 mmol) in
methanol (10 mL) was added and the colourless reaction mixture
was stirred for 1 h at room temperature. All the solvents were
removed and the crude product was dissolved in dichloromethane
(10 mL). The suspension was filtered through Celite to remove
NH4Cl and excess NH4PF6. Ethanol (15 mL) was added and the
solvent volume was reduced until precipitation of the product
was complete. The precipitate was filtered, washed with ethanol
(10 mL), petroleum ether (10 mL) and dried to give a light yellow
solid (39 mg, 48%). IR (neat): 1587, 1558, 1493, 1438, 1381, 1233,
1185, 1167, 1103, 1026, 1014, 998, 917, 830 (nP–F), 747 cm-1. 31P
NMR (acetone-d6): 9.1 (s, dppa) ppm. 1H NMR (acetone-d6): 2.34
1
1493, 1376, 1232, 1186, 918, 831 (nP–F), 761, 739, 696 cm-1. H
t
NMR (acetone-d6): 1.58 (s, 9H, Bu), 2.29 (s, 12H, o-CH3), 2.42
(s, 6H, p-CH3), 5.96 (d, 2H, o-NPh, JHH = 7.3 Hz), 7.20–7.24
(m, 1H + 4H, p-NPh + m-C6H2), 7.47 (t, 2H, m-NPh, JHH = 7.9
Hz), 8.23 (s, 2H, HC CH) ppm. MS (ES +ve; abundance): m/z
719 (100) [M]+, 440 (40) [M - Au(CNtBu)]+. Analysis: Calcd for
C33H38AuF6N4PS: C, 45.8; H, 4.4; N, 6.5. Found: C, 46.0; H, 4.6;
N, 6.3%.
[(IDip)Au(SCNPh·IMes)]PF6 (6). A dichloromethane solu-
tion (10 mL) of [AuCl(IDip)] (30 mg, 0.048 mmol) was treated with
a solution of 1 (23 mg, 0.053 mmol) in dichloromethane (10 mL).
NH4PF6 (16 mg, 0.096 mmol) in methanol (10 mL) was added
and the light yellow reaction mixture was stirred for 1 h at room
temperature. All the solvents were removed and the crude product
was dissolved in dichloromethane (10 mL). The suspension was
filtered through Celite to remove NH4Cl and excess NH4PF6.
Diethyl ether (20 mL) was added and the crude solid triturated
ultrasonically. The product was filtered, washed with diethyl ether
(10 mL), petroleum ether (10 mL) and dried to give a light yellow
solid (31 mg, 55%). IR (neat): 3149, 2965, 2927, 1557, 1459, 1384,
1227, 1184, 1060, 833 (nP–F), 759 cm-1. 1H NMR (acetone-d6): 1.14,
1.16 (d ¥ 2, 2 ¥ 12H, MeIDip, JHH = 6.9 Hz), 2.11 (s, 12H, o-CH3),
2.12 (s, 6H, p-CH3), 2.49 (sept, 4H, CHMeIDip, JHH = 6.8 Hz), 6.01
(d, 2H, o-NPh, JHH = 8.2 Hz), 6.70 (t, 1H, p-NPh, JHH = 6.8 Hz),
6.80 (t, 2H, m-NPh, JHH = 7.6 Hz), 7.09 (s, 4H, m-C6H2), 7.42
(d, 4H, m-C6H3, JHH = 7.8 Hz), 7.65 (t, 2H, p-C6H3, JHH = 7.8
Hz), 7.73 (s, 2H, HC CHIDip), 7.99 (s, 2H, HC CHIMes) ppm.
MS (ES +ve; abundance): m/z 1024 (100) [M]+, 440 (83) [M -
Au(IDip)]+. Analysis: Calcd for C55H65AuF6N5PS: C, 56.5; H, 5.6;
N, 6.0. Found: C, 56.4; H, 5.5; N, 5.9%.
(s, 24H, o-CH3), 2.35 (s, 12H, p-CH3), 6.02 (d, 4H, o-NPh, JHH
=
7.3 Hz), 6.42 (t, 2H, p-NPh, JHH = 7.3 Hz), 6.85 (t, 4H, m-NPh,
JHH = 7.8 Hz), 7.19 (s, 8H, m-C6H2), 7.63–7.75 (m, 20H, C6H5),
8.23 (s, 4H, HC CH) ppm. MS (FAB +ve; abundance): m/z 1812
(100) [M + PF6]+, 1030 (100), [M - Au(SCNPh·IMes)]+. Analysis:
Calcd for C82H78Au2F12N6P4S2: C, 50.3; H, 4.0; N, 4.3. Found: C,
50.4; H, 4.1; N, 4.2%.
[(dppf){Au(SCNPh·IMes)2}](PF6)2 (9). A dichloromethane
solution (10 mL) of [(dppf)(AuCl)2] (42 mg, 0.041 mmol)
was treated with a solution of 1 (40 mg, 0.091 mmol) in
dichloromethane (10 mL). NH4PF6 (20 mg, 0.123 mmol) in
methanol (10 mL) was added and the light orange reaction mix-
ture was stirred for 1 h at room temperature. All the solvents were
removed and the crude product was dissolved in dichloromethane
(10 mL). The suspension was filtered through Celite to remove
NH4Cl and excess NH4PF6. Ethanol (15 mL) was added and the
solvent volume was reduced until precipitation of the product
was complete. The precipitate was filtered, washed with ethanol
(10 mL), petroleum ether (10 mL) and dried to give a light orange
solid (35 mg, 40%). IR (neat): 1587, 1557, 1492, 1438, 1382, 1232,
1183, 1171, 1102, 1031, 999, 954, 918, 830 (nP–F), 748 cm-1. 31P
[(dppb){Au(SCNPh·IMes)2}](PF6)2 (7). A dichloromethane
solution (10 mL) of [(dppb)(AuCl)2] (30 mg, 0.034 mmol)
was treated with a solution of 1 (37 mg, 0.084 mmol) in
dichloromethane (10 mL). NH4PF6 (16 mg, 0.098 mmol) in
methanol (10 mL) was added and the light yellow reaction mixture
was stirred for 1 h at room temperature. All the solvents were
removed and the crude product was dissolved in dichloromethane
(10 mL). The suspension was filtered through Celite to remove
NH4Cl and excess NH4PF6. Ethanol (15 mL) was added and the
solvent volume was reduced until precipitation of the product
was complete. The precipitate was filtered, washed with ethanol
(10 mL), petroleum ether (10 mL) and dried to give a light yellow
solid (41 mg, 61%). IR (neat): 3162, 2920, 1585, 1491, 1437, 1382,
1233, 1185, 1105, 918, 834 (nP–F), 743 cm-1. 31P NMR (acetone-d6):
34.2 (s, dppb) ppm. 1H NMR (acetone-d6): 1.38, 2.10 (m ¥ 2, 2 ¥
4H, CH2), 2.33 (s, 12H, p-CH3), 2.36 (s, 24H, o-CH3), 6.06 (d, 4H,
o-NPh, JHH = 7.6 Hz), 6.68 (t, 2H, p-NPh, JHH = 7.2 Hz), 6.86
(t, 4H, m-NPh, JHH = 8.0 Hz), 7.20 (s, 8H, m-C6H2), 7.42 (m, 8H,
m-C6H5), 7.54 (m, 8H, o-C6H5), 7.62 (m, 4H, p-C6H5), 8.19 (s, 4H,
HC CH) ppm. MS (FAB +ve; abundance): m/z 1844 (13) [M +
PF6]+, 623 (100) [M - Au(SCNPh·IMes)2]+. Analysis: Calcd for
C84H86Au2F12N6P4S2: C, 50.7; H, 4.4; N, 4.2. Found: C, 50.8; H,
4.3; N, 4.2%.
1
NMR (acetone-d6): 31.8 (s, dppf) ppm. H NMR (acetone-d6):
2.32 (s, 24H, o-CH3), 2.35 (s, 12H, p-CH3), 3.97, 4.45 (s ¥ 2, 2 ¥
4H, C5H4), 6.14 (d, 4H, o-NPh, JHH = 6.7 Hz), 6.52 (t, 2H, p-NPh,
JHH = 7.1 Hz), 6.82 (t, 4H, m-NPh, JHH = 7.7 Hz), 7.18 (s, 8H,
m-C6H2), 7.20–7.30, 7.54–7.68 (m ¥ 2, 20H, C6H5), 8.19 (s, 4H,
HC CH) ppm. MS (FAB +ve; abundance): m/z 1972 (28) [M +
PF6]+, 751 (100) [M - Au(SCNPh·IMes)2]+. Analysis: Calcd for
C90H86Au2F12FeN6P4S2: C, 51.0; H, 4.1; N, 4.0. Found: C, 51.2; H,
4.0; N, 3.9%.
[(dppm)Au2(SCNPh·IMes)](PF6)2/(OTf)2 (10). Procedure A:
A dichloromethane solution (10 mL) of [(dppm)(AuCl)2] (35
mg, 0.042 mmol) was treated with a solution of 1 (20 mg, 0.045
mmol) in dichloromethane (10 mL). NH4PF6 (20 mg, 0.124
mmol) in methanol (10 mL) was added and the colourless
reaction mixture was stirred for 1 h at room temperature. All
the solvents were removed and the crude product was dissolved in
dichloromethane (10 mL). The suspension was filtered through
Celite to remove NH4Cl and excess NH4PF6. Ethanol (15 mL)
was added and the solvent volume was reduced until precipitation
of the product was complete. The precipitate was filtered, washed
with ethanol (10 mL), petroleum ether (10 mL) and dried to give
a light yellow solid (29 mg, 47%). Repeated recrystallisation from
6654 | Dalton Trans., 2011, 40, 6645–6658
This journal is
The Royal Society of Chemistry 2011
©

View Article Online
dichloromethane and ethanol was required to obtain a sample of
good purity. Procedure B: [(dppm)(AuCl)2] (96.6 mg, 0.114 mmol)
was dissolved in dry tetrahydrofuran (10 mL) and a solution of
silver triflate (58.4 mg, 0.227 mmol) in dry tetrahydrofuran (5 mL)
was added under nitrogen. The reaction mixture was stirred for 45
min in the dark at 0 ◦C. It was filtered into a tetrahydrofuran (5 mL)
solution of 1 (50 mg, 0.114 mmol). Stirring was continued for 2 h at
0 ◦C and then all the solvent was removed. The crude product was
dissolved in dichloromethane (5 mL) and filtered through Celite.
Pentane was added until precipitation of the light yellow solid was
complete (127 mg, 74%). IR (neat, triflate salt): 1606, 1587, 1485,
1437, 1382, 1254, 1152, 1102, 1028, 999, 952, 912, 892, 856 cm-1.
31P NMR (CD2Cl2): 25.6, 32.8 (d ¥ 2, dppm, JPP = 56.9 Hz) ppm.
1H NMR (CD2Cl2): 2.18 (br s, 6H, o-CH3), 2.29 (s, 6H, o-CH3),
2.35 (s, 3H, p-CH3), 2.43 (br s, 3H, p-CH3), 3.70 (t, 2H, CH2, JHP
unresolved), 6.02 (d, 2H, o-NPh, JHH = 7.3 Hz), 6.36 (t, 1H, p-
NPh, JHH = 7.4 Hz), 6.67 (t, 2H, m-NPh, JHH = 7.6 Hz), 7.19 (s,
4H, m-C6H2), 7.35–7.56 (m, 20H, C6H5), 7.71 (s, 2H, HC CH)
ppm. MS (FAB +ve; abundance): m/z 1252 (50) [M + 2H2O]+,
1217 (5) [M]+. Analysis: Calcd for C53H51Au2F12N3P4S: C, 42.2; H,
3.4; N, 2.8. Found: C, 42.1; H, 3.3; N, 2.7%.
C57H58AgAuF9N6O3PS3·2CHCl3: C, 41.3; H, 3.5; N, 4.9. Found:
C, 40.7; H, 3.4; N, 4.7%.
[(Ph3P)Au(SOC·IMes)]PF6 (14). A dichloromethane solution
(10 mL) of [AuCl(PPh3)] (50 mg, 0.101 mmol) was treated with
a solution of IMes·COS (40 mg, 0.110 mmol) in dichloromethane
(10 mL). NH4PF6 (25 mg, 0.153 mmol) in methanol (10 mL)
was added and the light yellow reaction mixture was stirred for
1 h at room temperature. All the solvents were removed and the
crude product was dissolved in dichloromethane (10 mL). The
suspension was filtered through Celite to remove NH4Cl and excess
NH4PF6. Ethanol (15 mL) was added and the solvent volume
was reduced until precipitation of the product was complete. The
precipitate was filtered, washed with ethanol (10 mL), petroleum
ether (10 mL) and dried to give a light yellow solid (62 mg, 63%).
IR (neat): 3152, 1738, 1607, 1490, 1437, 1381, 1231, 1183, 1168,
1101, 1028, 1010, 999, 900, 831 (nP–F), 711 cm-1. 31P NMR (acetone-
1
d6): 37.8 (s, PPh3) ppm. H NMR (acetone-d6): 2.25 (s, 12H, o-
CH3), 2.37 (s, 6H, p-CH3), 7.19 (s, 4H, m-C6H2), 7.54–7.69 (m,
15H, C6H5), 8.15 (s, 2H, HC CH) ppm. MS (ES +ve; abundance):
m/z 823 (100) [M]+, 365 (100) [M - AuPPh3]+. Analysis: Calcd for
C40H39AuF6N2OP2S: C, 49.6; H, 4.1; N, 2.9. Found: C, 49.6; H,
4.1; N, 2.8%.
[Au(SCNPh·IMes)2](PF6) (11). A dichloromethane solution
(10 mL) of [AuCl(tht)] (20 mg, 0.062 mmol) was treated with
a solution of 1 (60 mg, 0.137 mmol) in dichloromethane (10 mL).
NH4PF6 (30 mg, 0.186 mmol) in methanol (10 mL) was added
and the light yellow reaction mixture was stirred for 1 h at room
temperature. All the solvents were removed and the crude product
was dissolved in dichloromethane (10 mL). The suspension was
filtered through Celite to remove NH4Cl and excess NH4PF6.
Ethanol (15 mL) was added and the solvent volume was reduced
until precipitation of the product was complete. The precipitate
was filtered, washed with ethanol (10 mL), petroleum ether
(10 mL) and dried to give a light yellow solid (41 mg, 54%).
IR (neat): 1556, 1492, 1233, 1188, 921, 878, 837 (nP–F), 759, 731,
[(Ph3P)Au(SOC·SIMes)]PF6 (15). A dichloromethane solu-
tion (10 mL)of [AuCl(PPh3)](50mg, 0.101mmol) was treated with
a solution of SIMes·COS (40 mg, 0.109 mmol) in dichloromethane
(10 mL). NH4PF6 (25 mg, 0.153 mmol) in methanol (10 mL) was
added and the colourless reaction mixture was stirred for 1 h at
room temperature. All the solvents were removed and the crude
product was dissolved in dichloromethane (10 mL) and filtered
through Celite to remove NH4Cl and excess NH4PF6. Ethanol
(15 mL) was added and the solvent volume was reduced until
precipitation of the product was complete. The precipitate was
filtered, washed with ethanol (10 mL), petroleum ether (10 mL)
and dried to give a colourless solid (59 mg, 60%). IR (neat): 1739,
1612, 1573, 1481, 1437, 1381, 1289, 1217, 1101, 1029, 999, 877,
833 (nP–F), 711 cm-1. 31P NMR (acetone-d6): 37.4 (s, PPh3) ppm.
1H NMR (acetone-d6): 2.28 (s, 6H, p-CH3), 2.53 (s, 12H, o-CH3),
4.72 (s, 4H, CH2CH2), 7.08 (s, 4H, m-C6H2), 7.51–7.69 (m, 15H,
C6H5) ppm. MS (ES +ve; abundance): m/z 825 (40) [M]+, 367
(100) [M - AuPPh3]+. Analysis: Calcd for C40H41AuF6N2OP2S: C,
49.5; H, 4.3; N, 2.9. Found: C, 49.6; H, 4.2; N, 3.0%.
1
691 cm-1. H NMR (acetone-d6): 2.25 (s, 24H, o-CH3), 2.42 (s,
12H, p-CH3), 5.68 (d, 4H, o-NPh, JHH = 7.8 Hz), 6.75 (t, 2H,
p-NPh, JHH = 7.3 Hz), 6.89 (t, 4H, m-NPh, JHH = 7.7 Hz), 7.17
(s, 8H, m-C6H2), 8.03 (s, 4H, HC CH) ppm. 1H NMR (CD2Cl2):
2.22 (s, 24H, o-CH3), 2.45 (s, 12H, p-CH3), 5.68 (d, 4H, o-NPh,
JHH = 7.2 Hz), 6.75 (t, 2H, p-NPh, JHH = 7.4 Hz), 6.92 (t, 4H, m-
NPh, JHH = 7.8 Hz), 7.12 (s, 8H, m-C6H2), 7.37 (s, 4H, HC CH)
ppm. MS (ES +ve; abundance): m/z 1075 (100) [M]+, 440 (34) [M
- Au(SCNPh·IMes)]+. Analysis: Calcd for C56H58AuF6N6PS2: C,
55.1; H, 4.8; N, 6.9. Found: C, 55.0; H, 4.7; N, 6.8%.
[(tBuNC)Au(SOC·IMes)]PF6 (16). A dichloromethane solu-
tion (10 mL) of [AuCl(CNtBu)] (25 mg, 0.079 mmol) was
treated with a solution of IMes·COS (31.8 mg, 0.087 mmol) in
dichloromethane (10 mL). NH4PF6 (26 mg, 0.160 mmol) in
methanol (10 mL) was added and the light yellow reaction mixture
was stirred for 1 h at room temperature. All the solvents were
removed and the crude product was dissolved in dichloromethane
(10 mL). The suspension was filtered through Celite to remove
NH4Cl and excess NH4PF6. All the solvent was again removed
and diethyl ether (15 mL) added. Ultrasonic trituration produced
a colourless product. This was filtered, washed with diethyl ether
(10 mL) and dried (50 mg, 80%). IR: 2240 (nCN), 1608, 1490, 1376,
[AuAg(SCNPh·IMes)2](PF6)(OTf) (12). Silver triflate (3 mg,
0.012 mmol) was added to a solution of [Au(SCNPh·IMes)2](PF6)
(11) (13.5 mg, 0.011 mmol) in chloroform (10 mL) and the mixture
was stirred for 1 h at room temperature. All the solvent was
removed, diethyl ether (10 mL) was added and the product was
triturated ultrasonically. The yellow solid was filtered and dried
under vacuum. Yield: 13.8 mg (85%). IR (neat): 1590, 1491, 147,
1
1384, 1290, 1219, 1167, 1019, 909, 893, 837 (nP–F), 759 cm-1. H
NMR (CD2Cl2): 2.21 (s, 24H, o-CH3), 2.47 (s, 12H, p-CH3), 5.70
(d, 4H, o-NPh, JHH = 7.3 Hz), 6.98 (t, 2H, p-NPh, JHH = 7.3 Hz),
7.12 (t, 4H, m-NPh, JHH = 7.8 Hz), 7.19 (s, 8H, m-C6H2), 7.62
(s, 4H, HC CH) ppm. MS (FAB +ve; abundance) m/z: 1333 (3)
[M + OTf]+, 1183 (2) [M]+, 1075 (5) [M - Ag]+. Analysis: Calcd for
1
1233, 1183, 1010, 900, 831 (nP–F), 730 cm-1. H NMR (acetone-
t
d6): 1.63 (s, 9H, Bu), 2.22 (s, 12H, o-CH3), 2.40 (s, 6H, p-CH3),
7.20 (s, 4H, m-C6H2), 8.19 (s, 2H, HC CH) ppm. MS (ES +ve;
abundance): m/z 791 (39) [M + PF6]+, 365 (100) [M - IMes·COS]+.
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 6645–6658 | 6655
©

View Article Online
Analysis: Calcd for C27H33AuF6N3OPS: C, 41.1; H, 4.2; N, 5.3.
Found: C, 41.2; H, 4.0; N, 5.2%.
(s, 8H, m-C6H2), 7.47–7.73 (m, 20H, C6H5) ppm. MS (ES +ve;
abundance): m/z 1825 (10) [M + PF6]+, 1680 (2) [M]+, 1314 (21) [M
- SIMes·COS]+, 1177 (3) [M - Au(SIMes·COS)]+. Analysis: Calcd
for C78H80Au2F12FeN4O2P4S2: C, 47.5; H, 4.1; N, 2.8. Found: C,
47.6; H, 4.1; N, 2.7%.
[(tBuNC)Au(SOC·SIMes)]PF6 (17). A dichloromethane so-
lution (10 mL) of [AuCl(CNtBu)] (25 mg, 0.079 mmol) was
treated with a solution of SIMes·COS (32.0 mg, 0.087 mmol)
in dichloromethane (10 mL). NH4PF6 (26 mg, 0.160 mmol) in
methanol (10 mL) was added and the light yellow reaction mixture
was stirred for 1 h at room temperature. All the solvents were
removed and the crude product was dissolved in dichloromethane
(10 mL). The suspension was filtered through Celite to remove
NH4Cl and excess NH4PF6. All the solvent was again removed
and diethyl ether (15 mL) added. Ultrasonic trituration produced
a colourless product. This was filtered, washed with diethyl ether
(10 mL) and dried (58 mg, 93%). IR: 2239 (nCN), 1675, 1610, 1478,
[Au(SOC·IMes)2]PF6 (20).
A
dichloromethane solution
(10 mL) of [AuCl(tht)] (25 mg, 0.078 mmol) was treated with a
solution of IMes·COS (56.8 mg, 0.156 mmol) in dichloromethane
(10 mL). NH4PF6 (25.4 mg, 0.156 mmol) in methanol (10 mL)
was added and the light yellow reaction mixture was stirred for
1 h at room temperature. All the solvents were removed and the
crude product was dissolved in dichloromethane (10 mL). The
suspension was filtered through Celite to remove NH4Cl and excess
NH4PF6. All the solvent was again removed and diethyl ether
(15 mL) added. Ultrasonic trituration produced a pale yellow
product. This was filtered, washed with diethyl ether (10 mL)
and dried (80 mg, 96%). IR: 1606, 1557, 1489, 1380, 1289, 1230,
1184, 1169, 1034, 1010, 952, 901, 832 (nP–F), 769, 733, 724, 684,
1
1376, 1290, 1191, 1031, 877, 832 (nP–F), 738, 699 cm-1. H NMR
(acetone-d6): 1.63 (s, 9H, tBu), 2.33 (s, 6H, p-CH3), 2.50 (s, 12H,
o-CH3), 4.74 (s, 4H, CH2CH2), 7.10 (s, 4H, m-C6H2) ppm. MS
(ES +ve; abundance): m/z 795 (34) [M + PF6]+, 646 (2) [M]+, 367
(100) [M - SIMes·COS]+. Analysis: Calcd for C27H35AuF6N3OPS:
C, 41.0; H, 4.5; N, 5.3. Found: C, 41.0; H, 4.5; N, 5.5%.
1
662 cm-1. H NMR (acetone-d6): 2.18 (s, 24H, o-CH3), 2.36 (s,
12H, p-CH3), 7.12 (s, 8H, m-C6H2), 8.09 (s, 4H, HC CH) ppm.
MS (FAB +ve; abundance): m/z 925 (86) [M]+. Analysis: Calcd
for C44H48AuF6N4O2PS2: C, 49.3; H, 4.5; N, 5.2. Found: C, 49.5;
H, 4.4; N, 5.2%.
[(dppf){Au(SOC·IMes)}2](PF6)2 (18). A dichloromethane so-
lution (10 mL) of [(dppf)(AuCl)2] (25 mg, 0.025 mmol) was
treated with a solution of IMes·COS (19.7 mg, 0.054 mmol) in
dichloromethane (10 mL). NH4PF6 (12 mg, 0.074 mmol) in
methanol (10 mL) was added and the light yellow reaction mixture
was stirred for 1 h at room temperature. All the solvents were
removed and the crude product was dissolved in dichloromethane
(10 mL). The suspension was filtered through Celite to remove
NH4Cl and excess NH4PF6. All the solvent was again removed
and diethyl ether (15 mL) added. Ultrasonic trituration produced
a yellow product. This was filtered, washed with diethyl ether
(10 mL) and dried (32 mg, 66%). IR: 1609, 1487, 1437, 1381,
1312, 1239, 1176, 1103, 1035, 998, 932, 828 (nP–F), 749, 695 cm-1.
31P NMR (acetone-d6): 34.8 (s, PPh3) ppm. 1H NMR (acetone-d6):
2.29 (s, 24H, o-CH3), 2.33 (s, 12H, p-CH3), 3.89 (m, 4H, C5H4),
4.13 (m, 4H, C5H4), 7.22 (s, 8H, m-C6H2), 7.17–7.19, 7.48–7.52,
7.61–7.66 (m ¥ 3, 20H, C6H5), 7.97, 7.98 (s ¥ 2, 4H, HC CH)
ppm. MS (ES +ve; abundance): m/z 1964 (2) [M + 2PF6]+, 1822
(15) [M + PF6]+, 1676 (5) [M]+, 1115 (23) [M - Au(IMes·COS)]+.
Analysis: Calcd for C78H76Au2F12FeN4O2P4S2: C, 47.6; H, 3.9; N,
2.9. Found: C, 47.8; H, 4.0; N, 3.1%.
[Au(SOC·SIMes)2]PF6 (21).
A dichloromethane solution
(10 mL) of [AuCl(tht)] (25 mg, 0.078 mmol) was treated with a
solution of SIMes·COS (57.1 mg, 0.156 mmol) in dichloromethane
(10 mL). NH4PF6 (25.4 mg, 0.156 mmol) in methanol (10 mL)
was added and the light yellow reaction mixture was stirred for
1 h at room temperature. All the solvents were removed and the
crude product was dissolved in dichloromethane (10 mL). The
suspension was filtered through Celite to remove NH4Cl and excess
NH4PF6. All the solvent was again removed and diethyl ether
(15 mL) added. Ultrasonic trituration produced a pale yellow
product. This was filtered, washed with diethyl ether (10 mL)
and dried (68 mg, 81%). IR: 1667, 1610, 1568, 1481, 1379, 1350,
1216, 1199, 1156, 1115, 1030, 879, 832 (nP–F), 738, 702, 667 cm-1.
1H NMR (acetone-d6): 2.29 (s, 12H, p-CH3), 2.44 (s, 24H, o-
CH3), 4.67 (s, 8H, CH2CH2), 7.00 (s, 8H, m-C6H2) ppm. MS
(FAB +ve; abundance): m/z 929 (100) [M]+. Analysis: Calcd for
C44H50AuF6N4O2PS2: C, 49.3; H, 4.7; N, 5.2. Found: C, 49.3; H,
4.7; N, 5.0%.
[(dppf){Au(SOC·SIMes)}2](PF6)2 (19). A dichloromethane
solution (10 mL) of [(dppf)(AuCl)2] (25 mg, 0.025 mmol) was
treated with a solution of SIMes·COS (19.8 mg, 0.054 mmol)
in dichloromethane (10 mL). NH4PF6 (12 mg, 0.074 mmol) in
methanol (10 mL) was added and the light yellow reaction mixture
was stirred for 1 h at room temperature. All the solvents were
removed and the crude product was dissolved in dichloromethane
(10 mL). The suspension was filtered through Celite to remove
NH4Cl and excess NH4PF6. All the solvent was again removed
and diethyl ether (15 mL) added. Ultrasonic trituration produced
a yellow product. This was filtered, washed with diethyl ether
(10 mL) and dried (29 mg, 60%). IR: 1611, 1568, 1480, 1385,
1288, 1215, 1199, 1182, 1173, 1101, 1031, 831 (nP–F), 750, 693 cm-1.
Crystallography
Single crystals of 2, 3 and 13 were grown by vapour diffusion
of diethyl ether onto a dichloromethane solution of the complex.
Further details are given below and in the Supplementary In-
formation. The structures were refined using the SHELXTL and
SHELX-97 program systems.51
Crystal data for 2. [C46H44AuN3PS](PF6), M = 1043.81, triclinic,
¯
˚
P(no. 2), a = 13.3686(3), b = 13.7657(3), c = 14.6220(4) A, a =
111.492(2), b = 115.794(2), g = 90.1070(17)◦, V = 2212.12(11)
3
A , Z = 2, Dc = 1.567 g cm-3, m(Mo-Ka) = 3.506 mm-1,
˚
T
= 173 K, pale yellow blocks, Oxford Diffraction Xcalibur 3
diffractometer; 14763 independent measured reflections (Rint
=
31P NMR (acetone-d6): 30.8 (s, PPh3) ppm. H NMR (acetone-
0.0194), F2 refinement, R1(obs) = 0.0213, wR2(all) = 0.0375, 11951
independent observed absorption-corrected reflections [|Fo| >
4s(|Fo|), 2qmax = 66◦], 538 parameters. CCDC 773283.
1
d6): 2.20 (s, 12H, p-CH3), 2.48 (s, 24H, o-CH3), 4.26 (br s, 4H,
C5H4), 4.45–4.47 (m, 4H, C5H4), 4.74 (s, 8H, CH2CH2), 7.22
6656 | Dalton Trans., 2011, 40, 6645–6658
This journal is
The Royal Society of Chemistry 2011
©

View Article Online
Crystal data for 3. [C46H62AuN3PS](PF6), M = 1061.95, triclinic,
P (no. 2), a = 10.9296(2), b = 13.9751(3), c = 17.0449(3) A,
8 H. G. Raubenheimer, L. Lindeque and S. Cronje, J. Organomet. Chem.,
1996, 511, 177–184.
¯
˚
9 (a) P. de Fre´mont, N. M. Scott, E. D. Stevens and S. P. Nolan,
Organometallics, 2005, 24, 2411–2418; (b) M. R. Fructos, T. R.
a = 105.2760(19), b = 103.2896(18), g = 101.5936(18)◦, V
=
2347.48(9) A , Z = 2, Dc = 1.502 g cm-3, m(Cu-Ka) = 7.439
mm-1, T = 173 K, colourless blocks, Oxford Diffraction Xcalibur
PX Ultra diffractometer; 9279 independent measured reflections
(Rint = 0.0309), F2 refinement, R1(obs) = 0.0242, wR2(all) = 0.0602,
8743 independent observed absorption-corrected reflections [|Fo|
> 4s(|Fo|), 2qmax = 145◦], 539 parameters. CCDC 773284.
Crystal data for 13. [C58H58Ag2AuF6N6O6S4](CF3SO3)·CH2Cl2,
M = 1824.05, monoclinic, P2/c (no. 13), a = 1◦0.31542(15), b =
3
˚
Belderrain, P. de Fremont, N. M. Scott, S. P. Nolan, M. M. Diaz-
Requejo and P. J. Perez, Angew. Chem., Int. Ed., 2005, 44, 5284–5288;
(c) R. S. Ramo´n, N. Marion and S. P. Nolan, Tetrahedron, 2009, 65,
1767–1773; (d) N. Marion, R. S. Ramo´n and S. P. Nolan, J. Am. Chem.
Soc., 2009, 131, 448–449.
´
10 N. Kuhn and A. Al-Sheikh, Coord. Chem. Rev., 2005, 249, 829–857.
11 (a) P. L. Arnold and S. T. Liddle, Chem. Commun., 2006, 3959–3971;
(b) P. L. Arnold and I. J. Casely, Chem. Rev., 2009, 109, 3599–3611.
12 (a) D. Enders and T. Balensiefer, Acc. Chem. Res., 2004, 37, 534–541;
(b) D. Enders, O. Niemeier and A. Henseler, Chem. Rev., 2007, 107,
5606–5655; (c) N. Marion, S. D´ıez- Gonza´lez and S. P. Nolan, Angew.
Chem., Int. Ed., 2007, 46, 2988–3000.
13 (a) N. Kuhn, M. Steimann and G. Weyers, Z. Naturforsch., 1999, 54b,
427–433; (b) H. A. Duong, T. N. Tekavec, A. M. Arif and J. Louie,
Chem. Commun., 2004, 112–113; (c) A. Tudose, A. Demonceau and L.
Delaude, J. Organomet. Chem., 2006, 691, 5356–5365.
14 (a) A. M. Voutchkova, L. N. Appelhans, A. R. Chianese and R. H.
Crabtree, J. Am. Chem. Soc., 2005, 127, 17624–17625; (b) A. Tudose,
L. Delaude, B. Andre´ and A. Demonceau, Tetrahedron Lett., 2006, 47,
8529–8533; (c) A. M. Voutchkova, M. Feliz, E. Clot, O. Eisenstein and
R. H. Crabtree, J. Am. Chem. Soc., 2007, 129, 12834–12846; (d) X.
Sauvage, A. Demonceau and L. Delaude, Adv. Synth. Catal., 2009,
351, 2031–2038; (e) X. Sauvage, G. Zaragoza, A. Demonceau and L.
Delaude, Adv. Synth. Catal., 2010, 352, 1934–1948.
15 (a) W. S. Sheldrick, A. Scho¨nberg, E. Singer and P. Eckert, Chem. Ber.,
1980, 113, 3605–3609; (b) W. Krasuski, D. Nikolaus and M. Regitz,
Liebigs Ann. Chem., 1982, 1451–1465; (c) N. Kuhn, H. Bohnen and G.
Henkel, Z. Naturforsch., 1994, 49b, 1473–1480; (d) N. Kuhn, E. Niquet,
M. Steimann and I. Walker, Z. Naturforsch., 1999, 54b, 1181–1187.
16 L. Delaude, Eur. J. Inorg. Chem., 2009, 1681–1699.
˚
16.59529(19), c = 20.2361(3) A, b = 102.4511(14) , V = 3382.69(8)
A , Z = 2 [C2 symmetry], Dc = 1.791 g cm-3, m(Cu-Ka) = 11.489
3
˚
mm-1, T = 173 K, yellow plates, Oxford Diffraction Xcalibur
PX Ultra diffractometer; 6557 independent measured reflections
(Rint = 0.0353), F2 refinement, R1(obs) = 0.0524, wR2(all) = 0.1531,
5989 independent observed absorption-corrected reflections [|Fo|
> 4s(|Fo|), 2qmax = 145◦], 513 parameters. CCDC 784174.
Acknowledgements
We are grateful to Johnson Matthey Ltd for a generous loan
of hydrogen tetrachloroaurate. We thank Mr. Morgan Hans
(University of Lie`ge, Belgium) for his help with the synthesis of
IMes·COS and SIMes·COS.
17 (a) L. L. Borer and J. V. Kong, Inorg. Chim. Acta, 1986, 122, 145–148;
(b) L. L. Borer, J. V. Kong, P. A. Keihl and D. M. Forkey, Inorg. Chim.
Acta, 1987, 129, 223–226.
18 L. Delaude, X. Sauvage, A. Demonceau and J. Wouters,
Organometallics, 2009, 28, 4056–4064.
19 S. Naeem, A. Thompson, L. Delaude and J. D. E. T. Wilton-Ely, Chem.–
Eur. J., 2010, 16, 10971–10974.
20 L. Delaude, A. Demonceau and J. Wouters, Eur. J. Inorg. Chem., 2009,
1882–1891.
References
1 (a) Carbene Chemistry: From Fleeting Intermediates to Powerful
Reagents, ed. G. Bertrand, Marcel Dekker, New York, 2002; (b) N-
Heterocyclic Carbenes in Synthesis, ed. S. P. Nolan, Wiley-VCH,
Weinheim, 2006; (c) N-Heterocyclic Carbenes in Transition Metal
Catalysis (Topics in Organometallic Chemistry, Vol. 21), ed. F. Glorius,
Springer, Berlin, 2007.
2 (a) W. A. Herrmann and C. Ko¨cher, Angew. Chem., Int. Ed. Engl.,
1997, 36, 2162–2187; (b) L. Jafarpour and S. P. Nolan, Adv. Organomet.
Chem., 2001, 46, 181–222; (c) W. A. Herrmann, Angew. Chem., Int. Ed.,
2002, 41, 1290–1309; (d) W. A. Herrmann, T. Weskamp and V. P. W.
Bo¨hm, Adv. Organomet. Chem., 2002, 48, 1–69; (e) C. M. Crudden and
D. P. Allen, Coord. Chem. Rev., 2004, 248, 2247–2273; (f) N. M. Scott
and S. P. Nolan, Eur. J. Inorg. Chem., 2005, 1815–1828; (g) I. Dragutan,
V. Dragutan, L. Delaude and A. Demonceau, Arkivoc, 2005, 10, 206–
253; (h) J. C. Garrison and W. J. Youngs, Chem. Rev., 2005, 105, 3978–
4008; (i) F. E. Hahn and M. C. Jahnke, Angew. Chem., Int. Ed., 2008,
47, 3122–3172; (j) P. de Fre´mont, N. Marion and S. P. Nolan, Coord.
Chem. Rev., 2009, 253, 862–892 and following papers in this issue.
3 (a) S. P. Nolan, Eur. J. Inorg. Chem., 2009, 1664 and following papers
in this issue; (b) F. E. Hahn, Dalton Trans., 2009, 6893 and following
papers in this issue; (c) A. J. Arduengo III and G. Bertrand, Chem. Rev.,
2009, 109, 3209–3210.
4 (a) A. Igau, H. Grutzmacher, A. Baceiredo and G. Bertrand, J. Am.
Chem. Soc., 1988, 110, 6463–6466; (b) A. Igau, A. Baceiredo, G.
Trinquier and G. Bertrand, Angew. Chem., Int. Ed. Engl., 1989, 28,
621–622; (c) A. J. Arduengo III, R. L. Harlow and M. Kline, J. Am.
Chem. Soc., 1991, 113, 361–363; (d) A. J. Arduengo III, R. L. Harlow
and M. Kline, J. Am. Chem. Soc., 1991, 113, 2801; (e) A. J. Arduengo
III, Acc. Chem. Res., 1999, 32, 913–921; (f) D. Bourissou, O. Guerret,
F. P. Gabba¨ı and G. Bertrand, Chem. Rev., 2000, 100, 39–92.
5 (a) C. Samojłowicz, M. Bieniek and K. Grela, Chem. Rev., 2009, 109,
3708–3742; (b) G. C. Vougioukalakis and R. H. Grubbs, Chem. Rev.,
2010, 110, 1746–1787.
21 S. Naeem, L. Delaude, A. J. P. White and J. D. E. T. Wilton-Ely, Inorg.
Chem., 2010, 49, 1784–1793.
22 (a) J. D. E. T. Wilton-Ely, D. Solanki and G. Hogarth, Eur. J. Inorg.
Chem., 2005, 4027–4030; (b) E. R. Knight, D. Solanki, G. Hogarth, K.
B. Holt, A. L. Thompson and J. D. E. T. Wilton-Ely, Inorg. Chem., 2008,
47, 9642–9653; (c) E. R. Knight, N. H. Leung, A. L. Thompson, G.
Hogarth and J. D. E. T. Wilton-Ely, Inorg. Chem., 2009, 48, 3866–3874;
(d) E. R. Knight, A. R. Cowley, G. Hogarth and J. D. E. T. Wilton-Ely,
Dalton Trans., 2009, 607–609; (e) E. R. Knight, N. H. Leung, Y. H. Lin,
A. R. Cowley, D. J. Watkin, A. L. Thompson, G. Hogarth and J. D. E.
T. Wilton-Ely, Dalton Trans., 2009, 3688–3697.
23 (a) J. D. E. T. Wilton-Ely, P. J. Pogorzelec, S. J. Honarkhah and D. A.
Tocher, Organometallics, 2005, 24, 2862–2874; (b) J. D. E. T. Wilton-
Ely, S. J. Honarkhah, M. Wang and D. A. Tocher, Dalton Trans., 2005,
1930–1939; (c) J. D. E. T. Wilton-Ely, M. Wang, S. J. Honarkhah and
D. A. Tocher, Inorg. Chim. Acta, 2005, 358, 3218–3226; (d) J. D. E.
T. Wilton-Ely, M. Wang, D. Benoit and D. A. Tocher, Eur. J. Inorg.
Chem., 2006, 3068–3078.
24 (a) Y. Cheng, M.-F. Liu, D.-C. Fang and X.-M. Lei, Chem.–Eur. J.,
2007, 13, 4282–4292; (b) Q. Zhu, M.-F. Liu, B. Wang and Y. Cheng,
Org. Biomol. Chem., 2007, 5, 1282–1286.
25 (a) J. D. E. T. Wilton-Ely, A. Schier and H. Schmidbaur,
Organometallics, 2001, 20, 1895–1897; (b) J. D. E. T. Wilton-Ely, H.
Ehlich, A. Schier and H. Schmidbaur, Helv. Chim. Acta, 2001, 84,
3216–3232; (c) J. D. E. T. Wilton-Ely, A. Schier, N. W. Mitzel and H.
Schmidbaur, Inorg. Chem., 2001, 40, 6266–6271; (d) J. D. E. T. Wilton-
Ely, A. Schier, N. W. Mitzel, S. Nogai and H. Schmidbaur, J. Organomet.
Chem., 2002, 643–644, 313–323.
6 (a) N. Marion and S. P. Nolan, Chem. Soc. Rev., 2008, 37, 1776–1782;
(b) H. G. Raubenheimer and S. Cronje, Chem. Soc. Rev., 2008, 37, 1998–
2011; (c) J. C. Y. Lin, R. T. W. Huang, C. S. Lee, A. Bhattacharyya, W.
S. Hwang and I. J. B. Lin, Chem. Rev., 2009, 109, 3561–3598.
7 F. Bonati, A. Burini, B. R. Pietroni and B. Bovio, J. Organomet. Chem.,
1989, 375, 147–160.
26 Gold - Progress in Chemistry, Biochemistry and Technology, ed. H.
Schmidbaur, John Wiley & Sons, New York, 1999.
27 H. Schmidbaur and A. Schier, Chem. Soc. Rev., 2008, 37, 1931–
1951.
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 6645–6658 | 6657
©

View Article Online
28 H. Schmidbaur, P. Bissinger, L. Lachmann and O. Steigelmann, Z.
Naturforsch., 1992, 47b, 1711–1716.
29 H. Schmidbaur, A. Wohlleben, F. Wagner, O. Orama and G Huttner,
Chem. Ber., 1977, 110, 1748–1754.
30 (a) S. S. Tang, C.-P. Chang, I. J. B. Lin, L.-S. Liou and J.-C. Wang,
Inorg. Chem., 1997, 36, 2294–2300; (b) S. S. Tang, I. J. B. Lin, L.-S.
Liou and J.-C. Wang, J. Chin. Chem. Soc., 1996, 43, 327–335; (c) M.
Bardaji, A. Laguna and M. Laguna, J. Chem. Soc., Dalton Trans., 1995,
1255–1258.
31 M. Bardaji, M. Teresa de la Cruz, P. G. Jones, A. Laguna, J. Martinez
and M. Dolores Villacampa, Inorg. Chim. Acta, 2005, 358, 1365–1372.
32 (a) F. Canales, M. C. Gimeno, P. G. Jones, A. Laguna and C. Sarroca,
Inorg. Chem., 1997, 36, 5206–5211; (b) M. C. Gimeno and A. Laguna,
Gold Bull., 1999, 32, 90–95.
33 D. D. Heinrich, J. C. Wang and J. P. Fackler Jr., Acta Crystallogr., Sect.
C: Cryst. Struct. Commun., 1990, 46, 1444–1447.
34 F. Bonati, A. Burini, B. R. Pietroni and R. Galassi, Gazz. Chim. Ital.,
1993, 123, 691–695.
35 (a) M. Bardaji and A. Laguna, Eur. J. Inorg. Chem., 2003, 3069–3079;
(b) E. J. Ferna´ndez, A. Laguna and J. M. Lo´pez-de-Luzuriaga, Dalton
Trans., 2007, 1969–1981.
36 M. Hans, J. Wouters, A. Demonceau and L. Delaude, manuscript in
preparation.
39 A. Bondi, J. Phys. Chem., 1964, 68, 441–451.
40 M. E. Olmos, A. Schier and H. Schmidbaur, Z. Naturforsch., 1997,
52b, 203–208.
41 E. J. Ferna´ndez, J. M. Lo´pez-de-Luzuriaga, M. Monge, M. A.
Rodr´ıguez, O. Crespo, M. C. Gimeno, A. Laguna and P. G. Jones,
Chem.–Eur. J., 2000, 6, 636–644.
42 M. A. Rawashdeh-Omary, M. A. Omary and J. P. Fackler Jr., Inorg.
Chim. Acta, 2002, 334, 376–384.
43 M. Contel, J. Garrido, M. C. Gimeno, J. Jime´nez, P. G. Jones,
A. Laguna and M. Laguna, Inorg. Chim. Acta, 1997, 254, 157–
161.
44 M. I. Bruce, E. Horn, J. G. Matisons and M. R. Snow, Aust. J. Chem.,
1984, 37, 1163–1170.
45 J. Bailey, J. Inorg. Nucl. Chem., 1973, 35, 1921–1924.
46 D. T. Hill, G. R. Girard, F. L. McCabe, R. K. Johnson, P. D. Stupik,
J. H. Zhang, W. M. Reiff and D. S. Eggleston, Inorg. Chem., 1989, 28,
3529–3533.
47 (a) S. J. Berners-Price and P. J. Sadler, Inorg. Chem., 1986, 25, 3822–
3827; (b) M.-C. Brandys, M. C. Jennings and R. J. Puddephatt, J. Chem.
Soc., Dalton Trans., 2000, 4601–4606.
48 R. Uson, A. Laguna and J. Vicente, J. Organomet. Chem., 1977, 131,
471–475.
49 D. S. Eggleston, D. F. Chodosh, R. L. Webb and L. L. Davis,
Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1986, 42, 36–
38.
50 A. J. Arduengo, III, R. Krafczyk, R. Schmutzler, H. A. Craig, J. R.
Goerlich, W. J. Marshall and M. Unverzagt, Tetrahedron, 1999, 55,
14523–14534.
37 (a) P. G. Jones, Acta Crystallogr., Sect. C: Cryst. Struct. Commun.,
1984, 40, 1320–1322; (b) P. G. Jones, Acta Crystallogr., Sect. C: Cryst.
Struct. Commun., 1985, 41, 905–906; (c) P. G. Jones and R. J. Schelbach,
J. Chem. Soc., Chem. Commun., 1988, 1338–1339; (d) J. P. Fackler
Jr., M. N. I. Khan, C. King, R. J. Staples and R. E. P. Winpenny,
Organometallics, 1991, 10, 2178–2183.
51 (a) SHELXTL PC, version 5.1; Bruker AXS, Madison, WI, 1997; (b) G.
Sheldrick,SHELX-97, Institut Anorg. Chemie, Go¨ttingen, Germany,
1998.
38 S. Y. Ho and E. R. T. Tiekink, Z. Kristallogr. - New Cryst. Struct., 2004,
219, 73–74.
6658 | Dalton Trans., 2011, 40, 6645–6658
This journal is
The Royal Society of Chemistry 2011
©