Exploring the self-assembled tacticity in aurophilic polymeric arrangements of diphosphanegold(I) fluorothiolates

Article abstract of DOI:10.3390/molecules24234422

Despite the recurrence of aurophilic interactions in the solid-state structures of gold(I) compounds, its rational control, modulation, and application in the generation of functional supramolecular structures is an area that requires further development.

Full text of DOI:10.3390/molecules24234422

molecules
Article
Exploring the Self-Assembled Tacticity in Aurophilic
Polymeric Arrangements of Diphosphanegold(I)
Fluorothiolates
Guillermo Moreno-Alcántar 1,2,
*
, Laura Salazar 1, Guillermo Romo-Islas 1,
Marcos Flores-Álamo 1 and Hugo Torrens 1,
*
1
Facultad de Química, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico;
lauris.kawai@gmail.com (L.S.); memo_romo14@hotmail.com (G.R.-I.); mfa@unam.mx (M.F.-Á.)
Institut de Science et d’Ingénierie Supramoleculaires (ISIS), University of Strasbourg,
67083 Strasbourg, France
2
*
Correspondence: morenoalcantar@unistra.fr or lgma@comunidad.unam.mx (G.M.-A.);
torrens@unam.mx (H.T.); Tel.: +52-55-5622-3724 (G.M.-A)
ꢀꢁꢂꢀꢃꢄꢅꢆꢇ
Academic Editor: Laura Rodríguez
Received: 13 October 2019; Accepted: 2 December 2019; Published: 3 December 2019
ꢀꢁꢂꢃꢄꢅꢆ
Abstract: Despite the recurrence of aurophilic interactions in the solid-state structures of gold(I)
compounds, its rational control, modulation, and application in the generation of functional
supramolecular structures is an area that requires further development. The ligand effects over the
aurophilic-based supramolecular structures need to be better understood. This paper presents the
supramolecular structural diversity of a series of new 1,3-bis(diphenylphosphane)propane (dppp)
gold(I) fluorinated thiolates with the general formula [Au2(SRF)2(
µ
-dppp)] (SRF = SC6F5 (
1
); SC6HF4-4
); SC6H4F-2
(2
); SC6H3(CF3)2-3,5 (
3
); SC6H4CF3-2 (
4
); SC6H4CF3-4 (5); SC6H3F2-3,4 ( ); SC6H3F2-3,5 (
6
7
(8); SC6H4F-3 (
9); SC6H4F-4 (10)). These compounds were synthesized and characterized, and six of
their solid-state crystalline structures were determined using single-crystal X-ray diffraction. In the
crystalline arrangement, they form aurophilic-bridged polymers. In these systems, the changes in
the fluorination patterns of the thiolate ligands tune the aurophilic-induced self-assembly of the
compounds causing tacticity and chiral differentiation of the monomers. This is an example of the
use of ligand effects on the tune of the supramolecular association of gold complexes.
Keywords: gold; aurophilic; supramolecular chirality; tacticity
1. Introduction
Gold(I) coordination chemistry is intrinsically conjoined to supramolecular chemistry by the
aurophilic interactions [1–3]. These counterintuitive interactions, which have attracted attention since
the beginning of the twenty-first century, are still a subject of interest due to the potential applicability
of supramolecular gold assemblies in the production of materials including, for example, luminescent
materials, gelators, and liquid crystals [4–7]. In this quest, one of the main challenges is the rational
control of the aurophilic contact and its supramolecular consequences [8–12].
In gold(I) linear compounds, aurophilic contacts form whenever the volumes of the ligands
allow it [13
promote strong competing interactions, such as hydrogen bonding motifs, could avoid gold–gold
contacts [ 16]. If a truly rational use of aurophilicity as a supramolecular assembling tool could
–15]. Due to the high energy of the Au–Au contact, only the inclusion of synthons that
2,
be achieved, the recurrence of the contact must be ensured and the available tools to control their
directionality must be improved. Due to this lack in directionality, aurophilic-built architectures have
a tendency to form diverse aggregates even if they have similar ligands [17–22]. As a consequence,
Molecules 2019, 24, 4422; doi:10.3390/molecules24234422
www.mdpi.com/journal/molecules

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the fine-tuning of the characteristics of the ligands become important for building supramolecular
gold architectures. In the case of bisphosphane ligands, the length and flexibility of the bridging group
fundamentally influence the type of supramolecular network that will form [1].
Previously, we have reported the importance of the fluorothiolate ligand when choosing the
supramolecular packing motif in 1,2-bis(diphenylphosphane)ethane (dppe) gold(I) fluorothiolates [16].
Continuing with our research in this type of system, we synthesized and characterized a series of
10 new [Au2(SRF)2(
SC6H3(CF3)2-3,5 ( ); SC6H4(CF3)-2 (
); SC6H4F-3 ( ); SC6H4F-4 (10)) and 1,3-bis(diphenylphosphano)propane (dppp). The single-crystal
µ
-dppp)] derivatives containing fluorinated thiolates (SRF = SC6F5 (
1
); SC6HF4-4 (
2);
3
4
); SC6H4(CF3)-4 ( ); SC6H3F2-3,4 ( ); SC6H3F2-3,5 (
5
6
7); SC6H4F-2
(8
9
structure was determined for six of the obtained compounds. In contrast with our previous results—the
use of dppe allows the formation of diverse crystalline arrangements—the addition of one extra carbon
atom to the bridge using dppp seems to enhance the formation of polymeric chains, relegating the
influence of the fluorothiolate to a second plane (i.e., the fluorinated thiolates participate in the folding
of the lateral phenyl groups around the polymeric aurophilic metalorganic chain). The fluorinated
moieties influence the kind of interactions between neighboring chains. This influence of the fluorinate
groups is relevant in the supramolecular induction of particular arrangements, causing different kinds
of tacticity in the polymeric chains and chiral differentiation of the initially achiral molecular units.
Despite the growing attention on supramolecular tacticity and chirality [23
,24] and the interesting
features of aurophilic coordination polymers [25 27], to the extent of our knowledge, there is no
–
previous examination of the tacticity in this kind of system.
2. Results
Via X-ray diffraction, we determined the structure of six out of the 10 synthesized compounds
(Figures S1–S6). Table 1 lists bonding distances and angles around the gold atoms; all the bonding Au–P
and Au–S distances remained within fixed ranges close to 2.26 and 2.30 Å, respectively. The distortions
observed from the linearity expected for the P–Au–S moiety are mainly due to the formation of
the Au–Au contacts; however, no correlation exists between the aurophilic distance and the Au–S/P
bond distances, nor with the distortion angles, evidencing also a strong influence of packing effects.
The recurrence of the Au–Au interactions in all the compounds is evidence of the intensity of the
interaction despite the different electronic and steric properties of the used ligands.
Table 1. Selected angles (θ) and distances (d) in the reported compounds.
Compound dAu–Au (Å)
dAu–P (Å)
dAu–S (Å)
θP–Au–S (◦)
1
2
4
5
9
3.0924 (7)
3.0288 (6)
3.2276 (3)
3.2071 (5)
3.1475 (5)
3.1325 (3)
2.254 (2)
2.263 (1)
2.259 (1)
2.260 (1)
2.272 (2)
2.272 (3)
2.271 (1)
2.308 (2)
2.309 (1)
2.313 (1)
2.303 (1)
2.301 (2)
2.315 (3)
2.316 (1)
173.59 (7)
175.72 (7)
173.63 (4)
169.04 (4)
165.83 (5)
171.5 (1)
2.257 (1)
2.258 (1)
2.259 (1)
2.262 (3)
2.259 (1)
2.308 (1)
2.299 (1)
2.302 (1)
2.309 (3)
2.305 (1)
178.40 (4)
175.75 (4)
169.93 (5)
167.0 (1)
10
169.88 (4)
172.02 (4)
All the obtained structures display linear polymeric arrangements in which the adjacent
molecular units are linked by aurophilic contacts. Structures of and show syndiotactic polymers,
whereas compounds , and 10 crystallize forming polymeric isotactic arrangements. In all the
1
5
2, 4, 9
compounds, the two gold atoms of each molecular unit are inequivalent but, in all cases, the obtained
polymers are head-to-tail polymers with Au1–Au2 aurophilic interactions making all the gold to gold
distances identical.

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3. Discussion
3.1. Isotactic Polymers
Compounds
4
,
9
, and 10 crystallize in the triclinic P spatial group; in the three cases,
−1
two molecular units are related by the inversion center per unit cell and the aurophilic polymers
containing these units grow parallel to the a crystallographic axis in opposite directions from the other.
Figure 1 shows the unit cells within an overview of the polymeric growth. All three arrangements are
similar in terms of the polymer inside the backbone built by the aurophilic contacts and the phosphine
bridges. The volumes of the unit cells (1971.3, 1770.8, and 1731.3 Å3 for
4, 9, and 10, respectively) show
that the packing is considerably looser in 4.
Figure 1. View of the unit cells in the polymeric aggregates of compounds 4, 9, and 10.
In terms of the packing similarities, the molecular structures of the three compounds are also
similar with few conformational differences in the phenyl rings of the ligands. The overlap of the
molecular structure of these compounds is shown in Figure 2. The phosphine digold fragment remains
almost unchanged through the compounds having the main differences in the thiolate and phosphine
pendant phenyl groups. The biggest change is observed for compound 4 due to the difference in the
volume of trifluoromethyl groups in comparison with fluorine or hydrogen, which also explains the
decrease in the packing compactness observed in this compound.
Figure 2. Overlapping molecular structures of compounds 4 (blue), 9 (red), and 10 (green), showing
the similarities within this group of compounds.

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The self-aggregation of the molecular units of these compounds through the formation of
intermolecular aurophilic contacts yields the supramolecular linear polymers displayed in Figure 3.
In the three cases, the polymeric aggregate can be generated by simple translation operations from the
molecular unit, originating isotactic polymeric structures. Figure 3 distinguishes vicinal molecular
units, by alternating green and red, to demonstrate that the conformation of the units remains along
the polymeric chains. In these compounds, the supramolecular interactions holding together vicinal
chains are not particularly strong. The analysis of the packing revealed some H···F contacts, which do
not promote important changes in the morphology of the inner polymeric structure.
Figure 3. Isotactic aurophilic structures formed by compounds
4 (top), 9 (middle), and 10 (bottom),
showing the structurally equivalent alternating molecular units.
Compound
2 also forms isotactic polymeric chains in the crystalline packing, but, different
from the other isotactic arrangements, the vicinal molecular units cannot be generated from simple
translation operations, but are instead related by a second-order screw axis operation. Figure 4 shows
the polymeric arrangement and the lateral view of the compound, displaying the existence of this
relationship. The crystalline system of compound
2
is also different, showing a C2/C monoclinic
-stacking interactions
arrangement. The structural change in is related to the existence of strong
2
π
between neighboring chains (Figure S7). These interactions distort the molecular structure with respect
to the conformation observed in the other compounds. Thus, the increase in the fluorination degree of
compound 2 drives the change in the structural motif of the compound.

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Figure 4. Isotactic aurophilic structures formed by compound
2 (left) and the lateral view of the
polymeric chain showing the vicinal alternated monomers in red and green (right).
3.2. Syndiotactic Polymers
Compounds
translation or rotation operations; instead, they show conformational differences. Figure 5 shows the
polymeric aggregate in compound and a visualization over the polymer growth direction. Unlike the
previously examined compounds, the fluorinated phenyl rings exist in the same face of the polymeric
chain as a result of the appearance of πF πF stacking interactions. The neighboring units in the rigidity
1 and 5 form syndiotactic aggregates in which vicinal units are not related to simple
1
–
of the crystal arrangement are enantiomers. Thus, the minimal expression of the polymeric chain
consists of a r diad (i.e., a pair of enantiomeric molecular fragments) [28]. This relationship is due to the
crystalline packing and no evidence exists of its prevalence in solution as the polymeric arrangements
are broken by solvation.
Figure 5. Syndiotactic aurophilic structures formed by compound 1; the monomeric vicinal units are
indicated in red and green.
Similarly, compound
5 shows another kind of syndiotactic arrangement; in this case, the solvent
molecules in the crystalline packing participate in directing the trifluoromethyl groups of the molecule
to the same face, in which a layer of solvent molecules displays alternating Cl···H, Cl···F, and H···
F
interactions with the CF3 and hydrogen atoms in the phosphine phenyl rings (Figure S8). This facial
differentiation, caused by the supramolecular interactions in the crystal, results in a loss of symmetry
that yields to the formation of a syndiotactic polymer in which vicinal units of the polymer are
stereoisomers (Figure 6). As in compound 1, this relationship is inherent to the crystal packing
structure and thus, in principle, should not be maintained in solution because aurophilic interactions
are normally overcome by solvation.

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Figure 6. (Top) Syndiotactic aurophilic structures formed by compound 5, the monomeric vicinal
units are indicated in red and green. (Bottom) Conformation of the vicinal molecules showing their
enantiomeric relation.
4. Conclusions
We observed that the length of the bridge in the ligand 1,3-bis(diphenylphosphane)propane
promotes the formation of supramolecular aurophilic coordination polymers, rather than other
arrangements observed for different bridge lengths. In all the studied cases, the formation of the
central Au–Au contacts seems to be the main force directing the crystalline packing.
Our results show that in this series of gold(I) supramolecular polymers, the different interactions
promoted by the fluorinated moieties impacts the conformation of the molecular units, forming
the dominant aurophilic coordination polymeric chains; by changing the fluorination pattern in
the ancillary ligands, it is possible to induce structural properties such as tacticity and even chiral
differentiation of the units. The possibility of controlling the prevalence of these properties is a major
challenge in the building of self-assembled systems. This work demonstrated the feasibility of using
the ligand-induced modulation in that pursuit.
5. Materials and Methods
Fluorophenylthiols (HSRF), Pb(CH3COO)2, K[AuCl4], tetrahydrothiophene (tht), and 1,3-bis
(diphenylphosphano) propane were purchased from Sigma-Aldrich and used without additional
treatment. Solvents were obtained from JT Baker and used without previous treatment.
IR spectra were obtained using a Perkin-Elmer Spectrum 400 (PerkinElmer, Inc., Waltham, MA,
USA) in the range of 4000 to 400 cm−1 using attenuated total reflectance (ATR-FTIR). Elemental analysis
was performed with a Thermo Scientific Flash 200 (Thermo Fisher Scientific., Waltham, MA, USA) at
950 ◦C. NMR spectra were recorded on a 9.4 T Varian VNMRS spectrometer (Varian, Inc., Palo Alto,
CA, USA) in CDCl3. Chemical shifts are reported in ppm relative to internal TMS
13C) and to external references of CFCl3 (for 19F) and H3PO4 (for 31P) at 0 ppm. Positive-ion fast atom
δ
= 0 ppm (1H,

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bombardment mass spectrometry (FAB+MS) spectra were measured on an MStation JMS-700 (JEOL,
Ltd., Tokyo, Japan). Crystals were grown by slow (1 week) evaporation of solutions of the compounds
in chloroform.
5.1. Synthesis and Characterization
[AuCl(tht)] was synthesized by a modification of published methods [29,30]: A solution of 5.0 g
(13.2 mmol) of K[AuCl4] in a mixture of 25 mL of water and 5 mL of ethanol were mixed with 2.5 mL
(2.5 g, 28.35 mmol) of tetrahydrothiophene in a 100 mL round bottom flask (Caution: tht is highly
odorous and volatile, thus the procedure must be conducted in a fume hood; the materials can be
washed in a NaClO solution to mitigate the odor). The mixture was stirred for 1 h at room temperature
and the product appeared as a white precipitate. The precipitate was filtered and washed 2× with 25
mL ice-cold ethanol and 3× with 25 mL hexane.
[Au2Cl2(µ-dppp)] was synthesized according to previous reports [31]: We added 1.5 g (3.6 mmol)
of solid dppp to a suspension of 2 g (6.2 mmol) [AuCl(tht)] in 50 mL of a 1:1 mixture of CH2Cl2 and
acetone. After 2 h stirring at room temperature, a clear transparent solution was obtained. The solution
was concentrated by reduced pressure evaporation, and when the total volume was about 5 mL,
an excess of hexane (ca. 50 mL) was added causing the precipitation of the [Au2Cl2(dppp)] as a
white powder.
Pb(SRF)2: All lead thiolates were prepared by modification of previously published
methods [32–36]: To a solution of Pb(CH3COO)2 (5.2 mmol) in 100 mL water, thiol (HSRF) (10.0 mmol)
dissolved in about 10 mL of ethanol was added under vigorous stirring at room temperature. A white or
yellow precipitate was rapidly formed. The solid was filtrated and washed 3
×
with 50 mL methanol and
3
×
with 25 mL hexane. Caution: Lead derivatives are extremely toxic and must be handled following
the proper security procedures. Thiols and thiolates are odorous; consequently, all procedures must be
completed in a fume hood. IR spectra of the lead thiolates are available in the SI.
All 10 compounds were prepared in a similar manner so only the synthesis of compound
described in detail.
[Au2(SC6F5)2( -dppp)] (1). A solution of the precursor [Au2Cl2(dppp)] (210.0 mg; 0.24 mmol) in
1 is
µ
10 mL CH2Cl2 was mixed under stirring at room temperature with a solution (or suspension for most
of the less-fluorinated lead thiolates) of 170.0 mg (0.24 mmol) Pb(SC6F5)2 in 10 mL acetone. After 3 h of
stirring, we obtained a clear solution. The solvent was evaporated until a volume of about 3 mL and
then 20 mL of hexane was added to promote the precipitation of the product as a white powder. Yield:
75%; mp 193–195 ◦C; anal. C 39.2, H 1.8, S 4.8%, calcd for C39H26Au2F10S2P2, C 38.9, H 2.2 S 5.3%; IR
(ATR)
(12H, m,), 2.83 (4H, dt, J = 10.5, 7.2 Hz), 2.03–1.88 (2H, m); 31P-NMR (CDCl3, 162 MHz)
19F-NMR (CDCl3, 376.5 MHz)
35.32 (2F, m),1 65.24 (1F, m),1 66.80 (2F, m) ppm; FAB+ m/z 1401
[MAu]+ (20), 1005 [C33H26Au2F5P2S]+ (100).
[Au2(SC6HF4-4)2( -dppp)] (
). White powder. Yield: 76.5%. mp 171–173 ◦C; anal. C 40.3, H 2.1,
S 5.4%, calcd for C39H28Au2F8S2P2, C 40.1, H 2.4, S 5.5%; IR (ATR) 3079, 2861, 1625, 1424, 886
ν
max 3062, 2901, 1503, 1472, 967 cm−1; 1H-NMR (CDCl3, 400 MHz)
δ
7.67–7.61 (8H, m), 7.53–7.42
δ
27.94 ppm,
δ1
−
−
−
µ
2
ν
max
cm−1; 1H-NMR (CDCl3, 400 MHz)
δ
7.68–7.62 (8H, m), 7.52–7.41 (12H, m,), 6.68 (2H, tt, J = 9.8, 7.3 Hz),
28.39 ppm,
43.34 (2F, m) ppm; FAB+ m/z 1365 [MAu]+ (15), 987
2.83 (4H, dt, J = 10.5, 7.3 Hz), 1.97 (2H, tp, J = 14.7, 7.3 Hz); 31P-NMR (CDCl3, 162 MHz)
δ
19F-NMR (CDCl3, 376.5 MHz)
[C33H27Au2F4P2S]+ (100).
δ1
−
35.41 (2F, m),1
−
[Au2(SC6H3(CF)2-3,5)2(µ-dppp)] (3
). White powder. Yield: 66%. mp 125–128 ◦C; anal. C 39.5,
H 2.2, S 5.1%, calcd for C43H32Au2F12S2P2, C 39.8, H 2.5, S 4.9%; IR (ATR)
ν
2921, 2855, 1591,
max
1
1348, 1274, 1109 cm−1; H-NMR (CDCl3, 400 MHz)
δ 7.94 (4H, br, s), 7.69–7.63 (8H, m), 7.53–7.38
(14H, m), 2.88 (4H, dt, J = 10.4, 7.0 Hz), 1.97 (2H, tp, J = 16.3, 7.1 Hz); 31P-NMR (CDCl3, 162 MHz)
δ
28.21 ppm, 19F-NMR (CDCl3, 376.5 MHz)
[C35H29Au2F6P2S]+ (100).
δ
6 −5.79 (12F, s) ppm; FAB+ m/z 1493 [MAu]+ (15), 1051

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[Au2(SC6H4CF3-2)2(
µ
-dppp)] (
4
). White powder. Yield: 87%. mp 121–124 ◦C; anal. C 42.4, H 2.8, S
5.2%, calcd for C41H34Au2F6S2P2, C 42.4, H 2.9, S 5.5%; IR (ATR)
νmax 2921, 2859, 1436, 1309, 1100, 1027
cm−1; 1H-NMR (CDCl3, 400 MHz)
δ
7.68–7.58 (8H, m), 7.52–7.48 (12H, m), 6.96–6.85 (8H, m), 2.82 (4H,
dt, J = 10.5, 7.3 Hz), 1.96 (2H, tp, J = 14.8, 7.2 Hz); 31P-NMR (CDCl3, 162 MHz)
δ
29.28 ppm, 19F-NMR
(CDCl3, 376.5 MHz) δ −64.59 (6F, s) ppm; FAB+ m/z 1357 [MAu]+ (25), 983 [C34H30Au2F3P2S]+ (100).
[Au2(SC6H4CF3-4)2(µ-dppp)] (5
). White powder. Yield: 79%. mp 158–160 ◦C; anal. C 42.6, H 2.7,
S 5.1%, calcd for C41H34Au2F6S2P2, C 42.4, H 2.9, S 5.5%; IR (ATR)
νmax 2906, 2862, 1599, 1326, 1088
cm–1; 1H-NMR (CDCl3, 400 MHz)
δ
7.68–7.57 (12H, m), 7.51–7.39 (12H, m), 7.24 (4H, d), 2.83 (4H, dt,
J = 10.4, 7.2 Hz), 1.97 (2H, tp, J = 14.6, 7.2 Hz); 31P-NMR (CDCl3, 162 MHz)
δ
28.64 ppm, 19F-NMR
(CDCl3, 376.5 MHz) δ6 −4.73 (6F, s) ppm; FAB+ m/z 1357 [MAu]+ (45), 983 [C34H30Au2F3P2S]+ (100).
[Au2(SC6H3F2-3,4)2(µ-dppp)] (6
). White powder. Yield: 92%. mp 174–176 ◦C; anal. C 42.5, H 2.4,
S 5.6%, calcd for C39H32Au2F4S2P2, C 42.7, H 2.9, S 5.8%; IR (ATR)
cm−1; 1H-NMR (CDCl3, 400 MHz)
7.67–7.60 (8H, m), 7.53–7.41 (12H, m,), 7.33–7.27 (2H, m), 7.20–7.15
(2H, m), 6.83 (2H, dt, J = 10.5, 7.3 Hz), 2.84 (4H, dt, J = 10.5, 7.2 Hz), 2.02–1.85 (2H, m); 31P-NMR
(CDCl3, 162 MHz) 41.24 (2F, m), 147.95 (2F, m) ppm;
28.06 ppm, 19F-NMR (CDCl3, 376.5 MHz)
FAB+ m/z 1293 [MAu]+ (20), 951 [C33H29Au2F2P2S]+ (100).
[Au2(SC6H3F2-3,5)2( -dppp)] (
). White powder. Yield: 92%. mp 141–143 ◦C; anal. C 43.0, H 2.6,
S 5.5%, calcd for C39H32Au2F4S2P2, C 42.7, H 2.9, S 5.8%; IR (ATR) 3059, 2902, 1575, 1435, 978
νmax 2958, 2855, 1492, 1268, 1105
δ
δ
δ1
−
−
µ
7
ν
max
cm−1; 1H-NMR (CDCl3, 400 MHz)
tt, J = 9.1, 2.3 Hz), 2.85 (4H, dt, J = 10.5, 7.2 Hz), 1.96 (2H, tp, J = 14.7, 7.3 Hz); 31P-NMR (CDCl3, 162
MHz) 10.63 (4F, s) ppm; FAB+ m/z 1293 [MAu]+ (10),
26.39 ppm, 19F-NMR (CDCl3, 376.5 MHz)
951 [C33H29Au2F2P2S]+ (100).
[Au2(SC6H4F-2)2( -dppp)] (
S 6.2%, calcd for C39H34Au2F2S2P2, C 44.2, H 3.2, S 6.0%; IR (ATR)
cm−1; 1H-NMR (CDCl3, 400 MHz)
7.70–7.58 (8H, m), 7.52–7.38 (12H, m), 6.96–6.84 (8H, m), 2.82 (4H,
dt, J = 10.5, 7.3 Hz), 1.96 (2H, tp, J = 14.8. 7.3 Hz); 31P-NMR (CDCl3, 162 MHz) 27.95 ppm, 19F-NMR
(CDCl3, 376.5 MHz)
07.70 (2F, m) ppm; FAB+ m/z 1257 [MAu]+ (30), 933 [C33H30Au2FP2S]+ (100).
[Au2(SC6H4F-3)2( -dppp)] (
). White powder. Yield: 80%. mp 168–170 ◦C; anal. C 44.1, H 3.0, S
5.7%, calcd for C39H34Au2F2S2P2, C 44.2, H 3.2, S 6.0%; IR (ATR) max 2926, 2871, 1568, 1462, 1104
cm−1; 1H-NMR (CDCl3, 400 MHz)
7.68–7.59 (8H, m), 7.51–7.37 (12H, m), 7.33–7.23 (4H, m), 7.01 (2H,
δ 7.68–7.62 (8H, m), 7.54–7.41 (12H, m,), 7.11–6.97 (4H, m), 6.43 (2H,
δ
δ
1
−
µ
8
). White powder. Yield: 67%. mp 138–140 ◦C; anal. C 44.5, H 3.1,
max 3055, 2928, 1464, 1435, 1102
ν
δ
δ
δ
1
µ
−
9
ν
δ
td, J = 8.0, 6.3 Hz), 6.67 (2H, ttd, J = 8.3, 2.5, 1.0 Hz), 2.84 (4H, dt, J = 10.5, 7.3 Hz), 1.96 (2H, tp, J = 14.8,
7.2 Hz); 31P-NMR (CDCl3, 162 MHz)
δ
28.56 ppm, 19F-NMR (CDCl3, 376.5 MHz) δ −116.90 (2F, s) ppm;
FAB+ m/z 1257 [MAu]+ (23), 933 [C33H30Au2FP2S]+ (100).
[Au2(SC6H4F-4)2(
S 5.6%, calcd for C39H34Au2F2S2P2, C 44.2, H 3.2, S 6.0%; IR (ATR)
cm−1; 1H-NMR (CDCl3, 400 MHz)
7.64-7.59 (8H, m), 7.49–7.36 (16H, m), 6.77–6.71 (4H, m), 2.81 (4H,
µ
-dppp)] (10). White powder. Yield: 80%. mp 178–180 ◦C; anal. C 44.3, H 3.4,
max 2905, 2861, 1598, 1327, 1089
ν
δ
dt, J = 10.6, 7.4 Hz), 1.93 (2H, tp, J = 14.9, 7.5 Hz); 31P-NMR (CDCl3, 162 MHz)
δ
32.11 ppm, 19F-NMR
(CDCl3, 376.5 MHz) δ1 −20.62 (2F, s) ppm; FAB+ m/z 1257 [MAu]+ (35), 933 [C33H30Au2FP2S]+ (100).
5.2. Crystal Structure Determination
A suitable single crystal of compounds 1, 2, 4, 5, 9, and 10 were mounted on a glass fiber and
crystallographic data were collected with an Oxford Diffraction Gemini “A” diffractometer with a
Charge Coupled Device (CCD)area detector with monochromator of graphite for λMoKα = 0.71073 Å.
CrysAlisPro and CrysAlis RED software packages were used for data collection and integration [37].
The double pass scanning method was used to exclude any noise. The collected frames were integrated
using an orientation matrix determined from the narrow frame scans. Final cell constants were
determined by global refinement; collected data were corrected for absorbance using analytical
numeric absorption correction, using a multifaceted crystal model based on expressions upon the Laue
symmetry with equivalent reflections [38]. Structures solutions and refinement were conducted with
the SHELXS-2014 [39] and SHELXL-2014 [40] packages. WinGX v2018.3 [41] software was used to

Molecules 2019, 24, 4422
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prepare material for publication. Full-matrix least-squares were refined by minimizing (Fo2 − Fc2)2.
All non-hydrogen atoms were refined anisotropically. H atoms attached to C atoms were placed in
geometrically idealized positions and refined as riding on their parent atoms, with C–H = 0.95–1.00 Å
and Uiso(H) = 1.2Ueq(C) for aromatic, methylene, and methine groups. Crystallographic data for all
complexes are presented in Tables S1–S18. The crystallographic data for the structures reported in this
paper were deposited with the Cambridge Crystallographic Data Centre (CCDC) as supplementary
publication no. CCDC 1957797–1957802. Copies of the data can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge, CB21EZ, U.K. (fax: (+44) 1223-336-033, e-mail:
deposit@ccdc.cam.ac.uk).
Supplementary Materials: The following are available online, supplementary figures, additional characterization
information and crystallographic information.
Author Contributions: Conceptualization, G.M.-A. and H.T.; Methodology, G.M.-A., L.S., G.R.-I. and M.F.-
Á
.;
formal analysis, G.M.-A.; Data curation, L.S., G.R.-I. and M.F.-
Á; Writing—original draft preparation, G.M.-A.;
Writing—review and editing, G.M.A. and H.T; Project administration, G.M.-A. and H.T; Funding acquisition, H.T.
Funding: This research was funded by CONACYT-Mexico, grant number CB-2012/177498 and postdoctoral grant
740732; DGAPA-UNAM grant IN210818 support is also strongly acknowledged.
Acknowledgments: We acknowledge the instrumental support of the Unit for Industry and Research Support
(USAII) at the Faculty of Chemistry of the UNAM, Mexico. G. Moreno-Alc
ántar thanks L. De Cola for the
helpful discussions.
Conflicts of Interest: The authors declare no conflict of interest
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2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).