Construction of luminescent gold(I) aryl thiolates via isonitrilegold(I) complexes: Influence of synthetic methodology and the thiolate ligand on structure and properties

Article abstract of DOI:10.1515/znb-2009-11-1233

Gold Thiolate Polymers ([ArSAu]_n) were prepared via two synthetic routes - the direct reaction of an aromatic thiolate (ArSH) with HAuCl₄, or the reaction of an isonitrilegold(I) chloride complex with a thiolate anion. The former rou

Full text of DOI:10.1515/znb-2009-11-1233

Construction of Luminescent Gold(I) Aryl Thiolates via Isonitrilegold(I)
Complexes: Influence of Synthetic Methodology and the Thiolate Ligand
on Structure and Properties
Robert E. Bachmana and Sheri A. Bodolosky-Bettisb
a Department of Chemistry, The University of the South, 735 University Avenue,
Sewanee, TN, 37383, USA
b Department of Chemistry, Georgetown University, 37th and O Sts, Washington, DC 20057, USA
Reprint requests to Prof. Robert E. Bachman. Fax: 931-598-1145. E-mail: rbachman@sewanee.edu
Z. Naturforsch. 2009, 64b, 1491 – 1499; received October 2, 2009
Dedicated to Professor Hubert Schmidbaur on the occasion of his 75th birthday
Gold thiolate polymers ([ArSAu]n) were prepared via two synthetic routes – the direct reaction of
an aromatic thiolate (ArSH) with HAuCl4, or the reaction of an isonitrilegold(I) chloride complex
with a thiolate anion. The former route, which is general to almost all thiols, yields an amorphous
and non-luminescent material. The latter route, which is more limited in scope, proceeds via an isoni-
trilegold(I) thiolate complex and typically yields a crystalline and luminescent material. Addition of
electron-donating groups to the thiol aromatic ring leads to more rapid polymer formation and loss of
luminescence while addition of electron-withdrawing groups slows or stops polymer formation and
leads to a red-shift of the luminescence of the final polymeric materials. Two isonitrilegold(I) thiolate
complexes with varying numbers of fluorine substituents on the thiolate aromatic ring were char-
acterized crystallographically – C8H17NCAu(p-FC6H4S) and C12H25NCAu(2,4-F2C6H3S). As the
fluorination of the aromatic ring increases, no significant changes were observed in the bond lengths
of the complexes; however, the intermolecular Au-S distances lengthen while the aurophilic interac-
tion distances decrease. These results suggest clear relationships between the molecular structure and
both the supramolecular structure and photophysical properties in these materials.
Key words: Gold Thiolates, Luminescence, Isonitrile Gold Complexes
Introduction
Gold thiolate complexes are a particularly important
class of gold complexes due, in part, to the high affinity
of gold for sulfur. In addition to the applications de-
scribed above, gold thiolates have been utilized com-
mercially in areas as diverse as metallopharmaceuti-
cals [8] and gilding inks [9]. Thiolate ligands are also
a mainstay of SAM surface chemistry [10] and gold
nanoparticle research [11], areas of significant inter-
est in recent years. Indeed, gold(I) thiolate polymers
are a key step in the Brust synthesis of gold nanopar-
ticles [12]. Despite their significant role in the prepa-
ration of gold nanoparticles, relatively little is known
about the structure and properties of the thiolate poly-
mers themselves. We have previously reported that the
supramolecular structure of the gold(I) phenylthiolate
polymers can have a dramatic impact on the photo-
physical properties of these materials [13]. Recently,
others have noted similar effects in a variety of gold
thiolate-based materials [14]. In our initial work, we
also noted that the supramolecular structure of these
Gold(I) complexes have attracted significant atten-
tion for at least the last two decades due to their unique
properties and numerous potential applications [1].
Perhaps the most distinctive feature of these com-
plexes is the ability of gold(I) to form aurophilic in-
teractions [2]. These strong non-covalent interactions
have been shown to be capable of stabilizing un-
usual coordination numbers and geometries around
a host of main-group elements [1], of creating un-
usual supramolecular structures [3] and of inducing
novel mesophase behavior in very simple systems [4].
The presence of aurophilic interactions has also been
shown to generate, or modify, luminescent behavior
in numerous gold-based complexes and materials [5].
Applications for gold complexes continue to be found
at an increasing rate and include areas as widespread
as hetero- and homogeneous catalysts [6] on the one
hand and chemosensors on the other [7].
c
0932–0776 / 09 / 1100–1491 $ 06.00 ꢀ 2009 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
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R. E. Bachman – S. A. Bodolosky-Bettis · Luminescent Gold(I) Aryl Thiolates
Scheme 1. Reactions leading to the for-
mation of [ArSAu]n polymers and their
reaction with two electron donor ligands.
Table 1. Synthetic Routes to Gold Thiolate Polymers and
Outcomes From These Reactions.
polymeric materials could be, at least partially, con-
trolled by the method of synthesis and/or post synthesis
treatment. In this study we explore the generality of our
synthetic methodology and probe the relationship be-
tween the structure of the thiolate and the supramolec-
ular structure and photophysical properties for the re-
sulting polymeric materials.
Thiol
PhSH
Route
A
B
A
B
A
B
A
B
A
B
A
B
Form
amorphous
crystalline
amorphous
crystalline
amorphous
isonitrile complex
amorphous
crystalline
amorphous
partially crystalline
amorphous
partially crystalline
soluble oligomer
Luminescent?
N
Y
N
Y
N
p-FC6H4SH
2,4-F2C6H3SH
o-CO2HC6H3SH
p-CH3C6H3SH
p-CH3OC6H3SH
t-BuC6H3SH
N
Y
N
N
N
N
N
Results and Discussion
As we have previously reported [13], the polymeric
species [PhSAu]n can be prepared by either direct re-
action of thiophenol with HAuCl4 or by reaction of
isonitrile gold(I) complexes, RNCAuCl, with the cor-
responding anionic thiolate. The latter reaction pro-
ceeds via initial substitution of the anionic ligand at
gold followed by loss of the relatively labile isoni-
trile ligand (Scheme 1). These different routes pro-
duced materials of identical elemental composition but
dramatically different physical properties. For the di-
rect reaction (route A), the resulting polymeric mate-
rial is amorphous and non-luminescent, while use of
the isonitrile complex as a synthon (route B) gener-
ates a highly crystalline and luminescent product. In
this work, we have sought to explore the generality of
these reactions with respect to the identity of the thi-
olate and the ancillary ligand. Additionally, we sought
to determine the impact of the thiolate identity on the
photophysical properties of the gold thiolate polymers.
Gold(I) thiolate polymers, [ArSAu]n, can be pre-
pared by direct reaction of essentially any aryl thiol
with HAuCl4 (Table 1). Notable exceptions are highly
fluorinated systems, such as HC6F4SH and C6F5SH,
which yield stable gold(III) complexes [15], and t-
BuC6H4SH, which produces a soluble oligomeric ma-
terial [16].
A / B
that shown in Fig. 1 assuming a slight tilt of the poly-
mer chain direction relative to the layer direction. The
agreement between this diffraction peak and the ex-
pectation based on the model structure improves sig-
nificantly (see Fig. 2 below) for crystalline samples,
providing confidence in the correctness of the model.
The broad features at higher angle are consistent with
expectations for in-layer Au–Au, π-π and Au–S con-
tacts.
In contrast, use of the isonitrilegold(I) chloride com-
plexes as a synthon for the production of crystalline
gold thiolate polymers proved to be of more limited
scope. Complexes prepared using thiolate ligands con-
taining more than one fluorine atom failed to lose the
isonitrile ligand, even after prolonged reaction times
and/or heating under reduced pressure. Rather, the
isonitrile complexes were isolated in good to excellent
yield by simply evaporating the reaction solvent. In-
terestingly, the presence of a single carboxylate group
seems to provide a situation intermediate between one
and two fluorine substitutents. In this case, the loss
As with the thiophenol, the resulting solids typi- of the isonitrile ligand occurs, albeit at a very slow
cally show XRD patterns (Fig. 1) consistent with an rate. In contrast, the use of aryl thiolates with electron-
amorphous material. While these patterns are relatively donating groups (CH3, t-Bu, OCH3) in the para posi-
featureless, the low angle peak can be correlated with tion results in rapid loss of the isonitrile ligand from
the distance expected for a layered structure such as the RNCAuSAr complex; however, the resulting ma-
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the vapor phase. This observation is consistent with the
relatively greater stability for the complexes prepared
by Schmidbaur and others based on bulky, and hence
non-volatile, isonitrile ligands [14b, 17].
The reversibility of the isonitrile complexation re-
action allows for the conversion of non-luminescent,
amorphous samples of selected [ArSAu]n materials
into their luminescent, crystalline forms via treatment
with a catalytic amount of an isonitrile (typically ≤
5 mol-% of n-BuNC). As we noted previously [12],
this amorphous to crystalline treatment can be effected,
although not in a synthetically useful way, by heating
the amorphous material strongly. For example, heat-
ing [PhSAu]n◦to just below its decomposition temper-
ature (∼ 230 C) results in an exothermic phase tran-
sition [13]. This behavior suggests that transformation
from the amorphous to the crystalline state is enthalpi-
cally favored, and the initial amorphous state found in
route A is the result of kinetic factors. Consequently,
it seems reasonable that the catalytic isonitrile plays
the role of a transport agent, dissolving “high energy”
amorphous monomers (or oligomers) and depositing
them onto “low energy” growing crystalline polymers.
If this model is correct, it suggests a potential method
for controlling the internal structure of gold thiolate
polymers prior to their reduction to gold nanoparticles,
and hence, a potential way to control structure in gold
nanoparticles.
Fig. 1. Top: XRD of amorphous [PhSAu]n prepared from
HAuCl4 and PhSH. Bottom: Model of a layered structure
consistent with the observed XRD pattern.
terials are less crystalline than the parent material and
show no luminescence.
This catalytic conversion process is most effective
In those systems where it occurs, the rate of isoni- when Ar = Ph or p-FC6H4. For materials with electron-
trile loss was also observed to be dependent on the donating groups, such as [p-CH3C6H4SAu]n, catalytic
molecular mass of the isonitrile ligand, with heavier treatment with RNC does enhance the crystallinity
(longer alkyl chain) ligands dissociating more slowly. of the material, particularly in the low-angle region
This kinetic stability has allowed us to crystallize sev- (Fig. 2), but does not produce the characteristic intense
eral examples of the RNCAuSAr complexes when R orange-red luminescence seen in the other materials.
contains at least five carbon atoms. These crystal struc- These results suggest that the ordering of gold-sulfur
tures, to be discussed below, provide significant in- moieties, and the formation of extended Au–S and
sight into the potential aggregation motifs in these sys- Au–Au contacts within the layer, are critical for pro-
tems and, consequently, the structural requirements for ducing luminescent behavior. In contrast, attempts at
generating luminescent materials. However, it is worth catalytic modification of highly fluorinated polymers,
noting that crystalline materials with appropriate thio- such as [2,4-F2C6H3SAu]n, result in dissolution of the
late ligands (for example, Ar = Ph, p-FC6H4) slowly polymer via complex formation with the added isoni-
convert to [ArSAu]n via loss of the isonitrile ligand, as trile. Indeed, addition of a stoichiometric amount of
seen previously [12].
C8H17NC to a sample of [2,4-F2C6H3SAu]n prepared
These synthetic results highlight several important by route A led to quantitative dissolution of the starting
points. First, the dependence of the rate of the second polymer and isolation of C8H17NCAuSAr as X-ray-
step of route B on the molecular mass of the isonitrile quality crystals in good yield. Similarly, reaction of
ligand suggests that the loss of the isonitrile to form any polymeric material with a non-volatile donor, such
[ArSAu]n is an equilibrium process ultimately driven as Ph3P, results in dissolution of the polymer and gen-
by LeChaˆtelier’s principle via loss of the isonitrile to eration of LAuSAr complexes (Scheme 1).
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R. E. Bachman – S. A. Bodolosky-Bettis · Luminescent Gold(I) Aryl Thiolates
Fig. 3. The emission spectra for [p-FC6H4SAu]n (black line)
and [PhSAu]n (grey line).
ing reduction to gold(I) [15]. Additionally, the inability
of the thiolate ligands containing even slightly bulky
substituents (e. g., p-CH3) to form luminescent mate-
rials illustrates the sensitivity of the supramolecular
structure to small steric changes, even in the periph-
ery of the ligands. It is also possible that the increased
electron-density in these thiolate ligands increases the
rate of ligand dissociation enough that the formation of
amorphous material is even more kinetically favored,
which might also be expected to hinder the effective-
ness of isonitriles as recrystallization agents.
Crystalline polymer samples of [PhSAu]n, [p-
FC6H4SAu]n and [o-CO2HC6H4SAu]n, prepared via
either route B or catalytic treatment of an amor-
phous sample of these materials produced in route A,
showed an intense orange luminescence. Addition
of an electron-withdrawing group in [p-FC6H4SAu]n
and [o-CO2HC6H4SAu]n results in a small red-shift
(47 nm) in the luminescence wavelength from 643 nm
for [PhSAu]n to 690 nm for [p-FC6H4SAu]n and
[o-CO2HC6H4SAu]n (Fig. 3). Based on their long
(∼ 5 ns) lifetimes, we [13] as well as others [18]
Fig. 2. Top: XRD pattern of [p-CH3C6H3SAu]n after
catalytic treatment with BuNC. Bottom: XRD Pattern of
[PhSAu]n after the same treatment. Note significantly higher
degree of crystallinity in the latter case in the high-angle re-
gion.
have previously assigned this low-energy emission as
arising from a metal-centered triplet state. The ob-
served red-shift seems to indicate that the presence of
electron-withdrawing groups stabilizes the ligand-to-
metal charge transfer excited state slightly.
The exquisite sensitivity of the reaction outcome to
the thiolate ligand’s electronic and steric structure is
also striking. As the electron density at sulfur is low-
ered by the addition of electron-withdrawing groups
to the aromatic ring, the lability of the isonitrile lig-
and decreases dramatically, such that RNCAuSAr is
favored over [ArSAu]n. Interestingly, this trend mirrors
our observation that strongly electron-deficient thio-
lates can form gold(III) complexes rather than affect-
The solid-state structure of [C8H17NCAu(p-
FC6H4S)] (Fig. 4) is essentially identical to those we
have previously reported for RNCAuSPh (R = C5H11
and C7H13) [13], with all the molecular bonding
parameters (Table 2) in agreement with expectations.
The supramolecular structure of these three systems
is also essentially identical, consisting of a “crinkled
tape” motif made up by aurophilic interactions and
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Table 2. Significant bond lengths and in-
termolecular contacts.
˚
Intramolecular bond lengths (A)
Au–S
Au–C
1.967(10)
1.978(7)
1.985(7)
1.970(4)
C–N
S–CAr
C5H11NCAuSPh
C7H13NCAuSPh
C8H17NCAuSC6H4F-p
C8H17NCAuSC6H3F2-2,4
2.272(2)
2.274(17)
2.270(2)
2.273(1)
1.144(1)
1.136(8)
1.121(8)
1.132(5)
1.772(7)
1.781(5)
1.775(6)
1.770(4)
˚
Intermolecular contacts (A)
Au ··· Au
3.786(1)
3.611(1)
3.569(1)
3.409(1)
Au ··· Sshort
3.663(2)
3.686(2)
3.709(2)
4.047(1)
Au ··· Slong
4.022(2)
4.060(2)
4.018(2)
–
C5H11NCAuSPh
C7H13NCAuSPh
C8H17NCAuSC6H4F-p
C8H17NCAuSC6H3F2-2,4
Fig. 5. Top: View of one molecule of C12H25NCAu-
(2,4,-F2C6H3S) showing the overall molecular geometry.
Bottom: View of the major intermolecular interactions,
Au–Au and C–H ··· F hydrogen bonding, responsible for the
supramolecular structure in this system.
the aggregation of these dimers through longer, and
presumably weaker, Au–S contacts.
The structure of the related difluoro complex,
[C12H25NCAu(2,4-F2C6H3S)], (Fig. 5) is similar to
the other complexes at the molecular level; however,
it is markedly different at the supramolecular scale. In
this case, the molecules are again organized into dis-
crete dimers via a pair of Au–S contacts and a single
aurophilic interaction. However, these dimers then ag-
gregate not through further Au–S contacts but through
a pair of complementary C–H ··· F hydrogen bonds in-
volving the para fluorine on one ring interacting with
the fairly acidic hydrogen at the 3-position (i. e., be-
tween the two fluorine atoms). The observed H–F dis-
Fig. 4. Top: View of an individual molecule of
C8H17NCAu(p-FC6H4S) showing the linear coordina-
tion geometry at gold. Bottom: A view of the “crinkled tape”
motif formed via Au–S and Au–Au interactions.
Au–S contacts (see Table 2). Given the pattern of
short and long Au–S contacts, the tape motif can be
thought of as arising in two distinct stages. The first is
the formation of dimeric units via two Au–S contacts
and one aurophilic interaction, while the second is
˚
tance of 2.78 A is comparable to those seen previously,
˚
which range from 2.36 to 2.86 A. It is worth noting that
while C–H ··· F interactions are weaker than classical
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R. E. Bachman – S. A. Bodolosky-Bettis · Luminescent Gold(I) Aryl Thiolates
hydrogen bonds, they have been found to make a sig- bile ligands, such as isonitriles, can be used to control
nificant contribution to packing of the molecules [19]. the solid-state structure of gold thiolate polymers, in
The significant alteration of the supramolecular struc- at least some cases. Moreover, we have shown that the
ture seen from the seemingly minor change in molec- electronic structure of the aromatic ring can be used to
ular structure from one fluorine atom to two is a stark tune the photophysical behavior of these novel lumi-
example of the subtle balance of forces responsible for nescent materials. Lastly, we have again demonstrated
packing in the solid state.
how the delicate interplay of forces such as hydrogen
bonding, metal-ligand interactions and aurophilic in-
teractions can generate surprising shifts in a solid-state
structure.
Given the constancy of the packing seen in systems
that yield luminescent materials, and the inability to
form luminescent material from an alternative packing
arrangement, it seems reasonable to conclude that the
aggregation motif plays an important role in the physi-
cal properties of the final polymeric material. We have
previously suggested a mechanism for the formation
of the luminescent forms of these polymers involv-
ing the self-assembly of the isonitrile complexes into
the motif seen in Fig. 4 followed by loss of the isoni-
trile ligands to yield a ladder polymer structure [13].
The results of this current work are completely con-
sistent with this conjecture; when the “crinkled tape”
can form, luminescent materials result, and when steric
factors or other intermolecular interactions disrupt this
packing motif, non-luminescent materials result. For
example, the inability of the complexes with electron-
donating groups, such as RNCAu(p-CH3C6H4S), is a
result of the steric cost of the substitution of a hydrogen
atom for a significantly larger group such as methyl
or methoxy. The presence of bulky groups at the aro-
matic ring generates a curvature to a growing thiolate
oligomer. When the curvature is large enough, as in
the t-Bu case, the result is the formation of a small
oligomer with a ring structure. This idea is supported
by the solubility of gold thiolate samples made from
t-BuC6H4S(H) regardless of synthetic route [16].
The intermolecular contacts present in these closely
related structures also present an interesting trend (Ta-
ble 2), particularly given the constancy of the bond
lengths between complexes. As the number of fluo-
rine atoms increases, the short intradimer Au–S contact
lengthens, and the aurophilic contact shortens. Hence,
it appears that the decrease in electron density at sul-
fur from the addition of strongly electron-withdrawing
groups on the aromatic ring results in weaker Au–S
interactions and concomitantly stabilize the aurophilic
interaction. These structural findings fit well with our
interpretation of the luminescence data above.
Experimental Section
General Information
Experiments were carried out in air unless otherwise
noted. Unless stated otherwise, all starting materials were
available commercially and used as received from the ven-
dor. Isonitrile complexes of gold(I)chloride, RNCAuCl (R =
n-alkyl), [Et4N][Au(SC6F4H)2] and Me2SAuCl were syn-
thesized via literature procedures [4, 15, 20].
1
1H, 19F, and 31P{ H} NMR spectra were recorded on a
Varian 300 spectrometer using the solvents specified. The
1H chemical shifts were internally referenced to TMS (δ =
0 ppm). 19F NMR spectra were externally referenced to
1
trifluoroacetic acid (δ = 0 ppm). 31P{ H} NMR spectra
were generally externally referenced to phosphoric acid (δ =
0 ppm) or triphenyl phosphate (0.0485 M, δ = −17.1 ppm).
Infrared spectra were recorded using neat solids on a Perkin
Elmer Spectrum One FT-IR spectrometer via an ATR attach-
ment. Fluorescence spectra were recorded on a FluoroMax-
2 spectrophotometer. All differential scanning calorimetry
(DSC) measurements were obtained using open aluminum
pans on a TA Instruments 2910 modulated DSC.
Synthesis of [SC H Au]
n
6
5
Method 1
Benzenethiol (2 mL, 19.5 mmol) was added dropwise to
a solution of HAuCl4 · H2O (1.60 g, 4.71 mmol) in EtOH
(30 mL). The mixture was left to stir for 30 min, during
which time a white precipitate formed, and the solution
turned from yellow to colorless. The solid was isolated by fil-
tration, washed with EtOH and ether, and dried in air. Yield:
1.24 g (86 %). – Anal. for C6H5SAu: calcd. C 23.54, H 1.65;
found C 23.47, H 1.54. – IR: ν = 1586, 1484, 1033, 739, and
491 cm−1. This material shows no luminescence.
Method 2
Conclusion
A solution of benzenethiol (0.035 mL, 0.34 mmol) and
KOH (19 mg, 0.34 mmol) in MeOH (5 mL) was added drop-
Through this work we have elaborated on our ini-
tial findings, showing that sterically unencumbered la- wise to a suspension of Me2SAuCl (100 mg, 0.34 mmol)
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in MeOH (10 mL), producing a pale-yellow solid. The mix- for C6H3F2SAu: calcd. C 21.06, H 0.88; found C 20.61,
ture was stirred for 2 h. The solid was isolated by filtration, H 0.78. – M. p. 178 – 180 ◦C (dec.).
washed with MeOH and ether, and dried in air. Yield: 0.094 g
(90 %). – IR: ν = 1586, 1484, 1033, 739, 491 cm−1
.
Synthesis of [p-CH C H SAu]
n
3
6 4
Method 1
Method 3
4-Methylbenzenethiol (0.932 g, 7.52 mmol) was added as
a solid to a solution of HAuCl4 · H2O (0.128 g, 0.376 mmol)
in EtOH. The resulting colorless precipitate was isolated by
filtration, washed with EtOH and dried in air. Yield: 0.095 g
(79 %). – Anal. for C7H7SAu: calcd. C 26.26, H 2.20; found
C 26.56, H 2.10. – M. p. 190 – 195 ◦C (dec.).
Benzenethiol (0.034 mL, 0.34 mmol) and KOH (19 mg,
0.34 mmol) were dissolved in MeOH (5 mL). This solution
was slowly added to a solution of C2H5NCAuCl (97 mg,
0.34 mmol) in MeOH (10 mL), immediately generating a
colorless precipitate, which was isolated by filtration. The
solid was washed with MeOH and ether and dried in air.
Yield: 0.084 g (82 %). Similar results were obtained using
C7H13NCAuCl and C5H11NCAuCl. – Anal. for C6H5SAu:
calcd. Au 64.34, C 23.54, H 1.65; found Au 64.14, C 23.67,
Method 2
A solution of 4-methylbenzenethiol (21 mg, 0.17 mmol)
and KOH (10 mg, 0.17 mmol) in MeOH was prepared and
added dropwise to a solution of C4H9NCAuCl (55 mg,
0.17 mmol) in MeOH, resulting in the formation of a color-
less precipitate. After 1 h, the solid was isolated by filtration,
washed with MeOH and ether and dried in air. Yield: 21 mg
(38 %). – Anal. for C7H7SAu: calcd. C 26.26, H 2.20; found
C 26.25, H 2.00. – M. p. 189 – 193 ◦C (dec.).
◦
H 1.57. – M. p. 168 – 172 C (dec). – IR: ν = 1586, 1484,
1032, 739, 490 cm−1. – Luminescence: λem = 464, 643 nm
with λex = 350 nm.
Synthesis of [p-FC H SAu]
n
6
4
Method 1
4-Fluorobenzenethiol (0.872 mL, 8.19 mmol) was
added dropwise to a solution of HAuCl4 · H2O (0.139 g,
0.409 mmol) in EtOH (20 mL). The mixture was left to stir
until a colorless precipitate formed and the solution turned
colorless. The solid was isolated by filtration and washed
with MeOH and ether and was dried in air. Yield: 0.120 g
(91 %). – Anal. for C6H4FSAu: calcd. C 22.23, H 1.24; found
C 22.94, H 1.21. No luminescence was observed in these
samples.
Synthesis of [p-t-BuC H S Au]
n
6
4
To a solution of HAuCl4 · H2O (0.100 g, 0.294 mmol)
in EtOH, t-butylbenzenethiol (0.494 mL, 2.94 mmol) was
added. The resulting pale-yellow solid was isolated by fil-
tration and washed with ether and dried in air. – 1H NMR
(CDCl3): δ = 1.16 (s), 1.30 (s), 1.32 (s), 6.90 (d), 7.27 (m),
7.52 (d), 7.59 (d), 7.68 (d).
Synthesis of [p-CH OC H SAu]
n
3
6 4
Method 2
Method 1
A
solution of 4-fluorobenzenethiol (0.035 mL,
4-Methoxybenzenethiol (0.282 mL, 2.30 mmol) was
added dropwise to a solution of HAuCl4 · H2O (0.156 g,
0.459 mmol) in EtOH (20 mL). After 30 min, the resulting
colorless solid was isolated by filtration, washed with MeOH
and ether, and dried in air. Yield 0.108 g (70 %). – Anal. for
C7H7OSAu: calcd. C 25.01, H 2.10; found C 25.11, H 2.09. –
M. p. 192 – 196 ◦C (dec.).
0.33 mmol) and KOH (0.019 g, 0.33 mmol) in MeOH was
prepared and added dropwise to a solution of C4H9NCAuCl
(0.141 g, 0.331 mmol) in MeOH. The mixture was left to
stir for ∼ 30 min during which time a colorless precipitate
formed. The solid was isolated by filtration, washed with
MeOH and ether and dried in air. Yield: 0.102 g (95 %). –
Anal. for C6H4FSAu: calcd. C 22.23, H 1.24; found C 21.48;
H 1.01. – Luminescence: λem = 450, 550, 690 nm with λex
330 nm.
=
Method 2
A solution of 4-methoxybenzenethiol (20 mg, 0.16 mmol)
and KOH (9 mg, 0.2 mmol) in MeOH was prepared and
added dropwise to a solution of C4H9NCAuCl (51 mg,
Synthesis of [2,4-F C H SAu]
n
2
6 3
2,4-Difluorobenzenethiol (1.29 mL, 2.30 mmol) was 0.16 mmol) in MeOH. The mixture was left to stir for 1 h
added dropwise to a solution of HAuCl4 · H2O (0.260 g, during which time a colorless precipitate formed. The solid
0.767 mmol) in EtOH. The solution was left to stir for was isolated by filtration, washed with MeOH and ether, and
approximately 2 h. The colorless precipitate that formed dried in air. Yield: 0.034 g (62 %). – Anal. for C7H7OSAu:
was isolated by filtration, washed with EtOH and ether calcd. C 25.01, H 2.10; found C 24.88, H 1.98. – M. p. 191 –
and dried under suction. Yield: 0.235 g (90 %). – Anal. 194 ◦C (dec.).
Unauthenticated
Download Date | 12/3/15 12:21 PM

1498
R. E. Bachman – S. A. Bodolosky-Bettis · Luminescent Gold(I) Aryl Thiolates
Table 3. Crystal structure data for C8H17NCAu(p-FC6H4S)
and C12H25NCAu(2,4-F2C6H3S).
Synthesis of [o-CO HC H SAu]
n
2
6 5
Thiosalicylic acid (0.500 g, 3 mmol) was added as a solid
to a solution of HAuCl4 · H2O (0.201 g, 0.592 mmol) in
EtOH. The solution was allowed to stir for at least 1 h be-
fore isolating the resulting pale-yellow solid by filtration.
The solid was washed with ether and air-dried. Yield: 0.197 g
(95 %). – Anal. for C7H5O2SAu: calcd. C 24.00, H 1.44;
found C 23.99, H 1.66. – M. p. 260 – 265 ◦C (dec.). – IR: ν =
3384 (broad), 2916, 2847, and 1667 cm−1. – Luminescence:
λem = 470, 690 nm with λex = 350 nm.
C8H17NCAu-
(p-FC6H4S)
C12H25NCAu-
(2,4-F2C6H3S)
C19H28AuNSF2
537.47
0.56×0.44×0.08
monoclinic
P21/n
16.944(8)
7.5452(10)
17.936(2)
117.747(2)
2029.5(5)
4
1.76
73.7
1048
21, 9, 22
0.589
20777
4422 / 0.0537
219
0.0408/0.0639
1.007
0.92 / −1.05
Formula
Mr
C15H21AuNSF
463.35
0.5×0.18×0.04
monoclinic
C2/c
14.189(3)
5.4178(10)
41.909(8)
91.419(3)
3220.6(10)
8
1.91
92.6
1776
18, 6, 53
0.589
15835
3515 / 0.0522
174
0.0431/0.0828
1.229
1.00 / −2.54
Crystal size, mm3
Crystal system
Space group
˚
a, A
˚
b, A
˚
c, A
β, deg
3
˚
Synthesis of [(C H NC)Au(p-FC H S)]
8
7
6 4
V, A
Z
A
solution of 4-fluorobenzenethiol (0.013 mL,
Dcalcd, g cm−3
µ(MoKα ), cm−1
F(000), e
hkl range
0.13 mmol) and KOH (0.007 g, 0.1 mmol) was pre-
pared in MeOH and was slowly added to a solution of
n-octylisonitrile gold(I) chloride (0.054 g, 0.13 mmol) in
MeOH. The resulting solution was left to stir for ∼ 30 min,
during which time a cream-colored solid precipitated. The
solid was isolated by filtration and washed with MeOH
and ether. Yield: 0.023 g (35 %). X-Ray-quality crystals
were grown by placing the mother liquor in the freezer for
approximately 1 week. – IR: ν = 3089, 3061, 2856, 2246,
−1
˚
((sinθ)/λ)max, A
Refl. measured
Refl. unique / Rint
Param. refined
R(F)/wR(F2) (all refl.)
GoF (F2)
−3
˚
∆ρfin (max / min), e A
1873, 1585, 1481, 1395 cm−1
.
both solved via Direct Methods, which allowed essentially
all non-hydrogen atomic positions to be assigned. The re-
maining non-hydrogen atoms were located in the difference
map during refinement. All non-hydrogen atoms were refined
anisotropically. While the hydrogen atoms could be located
in the final difference maps, refinement of these atoms proved
unstable. Hence, the hydrogen atoms were included in the fi-
nal model using a standard riding model. The differences in
the hydrogen atom positions in these two models were found
to be negligible. Final crystallographic details are summa-
rized in Table 3.
CCDC 753256 and 753257 contain the supplementary
crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data request/cif.
X-Ray powder diffraction experiments were performed on
Synthesis of [C NCAu(2,4-F C H S)]
H
12 25
2 6 3
A
solution of 2,4-difluorobenzenethiol (0.018 mL,
0.16 mmol) and KOH (0.009 g, 0.2 mmol) in MeOH was
added to a solution of n-dodecylisonitrile gold (I) chloride
(0.050 g, 0.16 mmol) in MeOH. Upon stirring, the solu-
tion remained transparent and colorless. The solvent was re-
moved in vacuo and a pasty colorless solid remained. Yield:
0.036 g (53 %).
X-Ray crystallography and diffraction
Single crystal X-ray data were collected on a Bruker-AXS
SMART CCD system equipped with a Bruker-AXS LT2 low
temperature device, using graphite-monochromatized MoKα
˚
radiation (λ = 0.71073 A). Initial unit cells were deter-
mined using least-squares analysis of a random set of re- a Rigaku R-Axis Rapid diffractometer equipped with an im-
flections collected from three series of 0.3◦ wide ω scans age plate detector. Graphite-monochromatized CuKα radia-
˚
(20 frames/series) well distributed in reciprocal space. The tion (λ = 1.5419 A) was used throughout. The samples were
intensity data were then collected with 0.3◦ wide ω scans mounted onto the goniometer head in 0.1 mm glass capil-
and a crystal-to-detector distance of 5.0 cm, providing a com- laries. A CCD microscope camera was used to position the
plete sphere of data to a maximum resolution of approxi- desired region of the sample in the X-ray beam and align
mately 0.75 A (2θmax = 56.6◦). The data were corrected for it approximately perpendicular to the beam. The plate im-
˚
Lorentz and polarization effects as well as absorption. An ages were converted to standard I vs. 2θ plots using the
empirical absorption correction was made on the basis of integration software included with the instrument, and the
equivalent reflection measurements using Blessing’s method data were analyzed with JADE 5 PATTERN processing soft-
as incorporated into the program SADABS [21]. Structure so- ware. Background corrections were made by manual sub-
lution and visualization was carried out with the SHELXTL traction of the XRD pattern obtained from an empty capil-
and X-SEED software packages [22, 23]. The structures were lary.
Unauthenticated
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R. E. Bachman – S. A. Bodolosky-Bettis · Luminescent Gold(I) Aryl Thiolates
1499
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Unauthenticated
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