Dinuclear Gold(I) Chloride Complexes with Diarsine Ligands

Article abstract of DOI:10.1002/ejic.202000810

Recently, we have developed synthetic methods for preparing diarsenic ligands. Herein, dinuclear gold(I) chloride complexes with various kinds of diarsenic ligands [Au₂Cl₂(diars)] were synthesized (diars = dpae, dpap, dpab, cis-dpav,

Full text of DOI:10.1002/ejic.202000810

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Diarsine Ligands
Dinuclear Gold(I) Chloride Complexes with Diarsine Ligands
Ryosuke Kobayashi,[a] Toshiki Fujii,[a] Hiroaki Imoto,*[a,b] and Kensuke Naka*[a,b]
Abstract: Recently, we have developed synthetic methods for because of the flexible alkylene linkers of the diarsine ligand.
preparing diarsenic ligands. Herein, dinuclear gold(I) chloride The emission behaviors of the complexes were drastically
complexes with various kinds of diarsenic ligands [Au2Cl2(diars)] changed by the ligands, which should affect the energy barrier
were synthesized (diars = dpae, dpap, dpab, cis-dpav, trans- for internal conversion from the intraligand excitation state to
dpav, dpapz, and dpaq). X-ray crystallography revealed that the halide-to-ligand charge transfer one. Some of the com-
they can form intra- or intermolecular aurophilic interactions plexes accordingly showed luminescent mechanochromism
depending on the ligand structure except for dpab. Crystal and/or thermochromism.
polymorphs of Au2Cl2(dpae) and Au2Cl2(dpap) were observed
Introduction
highly affect the electron transition energies via conformational
change.[4c,7]
Trivalent arsenic atom has soft Lewis basicity, large atomic size,
weak σ-donation, and high air-stability, when compared with
phosphorus one.[1] Accordingly, transition metal complexes
with arsenic ligands can show excellent functions and interest-
ing behaviors as catalyst,[2] luminophore,[3] stimuli-responsive
material,[4] etc. Gold(I) complexes with arsenic ligands in partic-
ular have unique structures and properties because the soft
Lewis basicity of arsenic atom can enhance Au···Au interactions,
called aurophilic interactions.[5] Aurophilic interaction often ex-
hibits phosphorescence due to 5dσ*-6pσ electron transition,
which is dependent on the Au···Au distance. Since bonding en-
ergy of aurophilic interaction is comparable to that of hydrogen
bond, external stimuli can induce elongation, shortening, for-
mation, or cleavage of Au···Au bonds to cause emission color
change.[6] Aurophilic networks are thus promising candidates
as stimuli-responsive materials. Since bidentate ligand structure
is suitable for construction of intra- and/or intermolecular auro-
philic interactions, some bidentate arsenic ligands have been
applied for aurophilic architectures.[3a,3e,3f,4c,7] Gold(I) halide
(AuX, X = Cl, Br, I) complexes with 1,2-bis(diphenylarsanyl)eth-
ane (dpae) varies luminescent properties depending on crystal
polymorphs.[3a] We also previously reported that one-dimen-
sional aurophilic chains of AuCl complexes are supported by
1,4-dihydro-1,4-diarsinines, and the substituents of the ligands
Despite the pioneering works, structures and properties of
gold(I) complexes with bidentate arsenic ligands have never
been systematically studied because of a lack of practical syn-
thetic methods for organoarsenic compounds. That is, there is
a serious concern to the danger of arsenic precursors such as
arsenic hydrides or chlorides, which were miserably misused as
chemical weapons. To address this issue, we have developed
practical synthetic routes that employ only non-volatile arsenic
precursors.[8] Cyclooligoarsines, which can be readily prepared
from inorganic arsenic precursors,[9] are key intermediates for
these strategies. Their As–As bonds are cleaved to generate var-
ious reactive species such as radical,[10] electrophile,[11] and nu-
cleophile.[12] The subsequent As–C bond formation reactions
efficiently produce various organoarsenic compounds.
We recently reported bidentate arsenic ligand library by fully
utilizing our synthetic protocols, and the ligands were applied
to Suzuki–Miyaura coupling reaction to elucidate the structure-
catalytic activity relationships.[13] In this work, we prepared bi-
dentate ligands with flexible (dpae, dpap, and dpab) or rigid
(cis-dpav, trans-dpav, dpapz, and dpaq) linkers as summarized
in Scheme 1. The dinuclear AuCl complexes with these ligands
were synthesized and the structures were analysed by X-ray
crystallography. The relationship between structures and lumi-
nescent behaviors were studied. This is the first systematic
study on AuCl complexes with arsenic ligands.
[a] R. Kobayashi, T. Fujii, Prof. Dr. H. Imoto, Prof. Dr. K. Naka
Faculty of Molecular Chemistry and Engineering, Graduate School of
Science and Technology, Kyoto Institute of Technology,
Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
E-mail: himoto@kit.ac.jp (H. I.)
kenaka@kit.ac.jp (K. N.)
http://www.cis.kit.ac.jp/~kenaka/index_eng.html
[b] Prof. Dr. H. Imoto, Prof. Dr. K. Naka
Materials Innovation Lab, Kyoto Institute of Technology,
Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org/10.1002/ejic.202000810.
Scheme 1. Chemical structures of bidentate arsenic ligands examined in the
present work.
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Results and Discussion
ance of the ligands were quite similar. It is thus evident that
the series of the arsenic ligands are suitable for studying struc-
tural effects of ligand backbone on aurophilic interactions with-
out changing the electron density on the gold(I) center. The
ligand structure drastically affected the form of aurophilic inter-
actions. Unlikely to the others, Au2Cl2(dpab) had no aurophilic
interactions in the crystalline state (Figure 1); the nearest intra-
and intermolecular Au···Au distances were 8.612(3) and 5.788(2)
Å, respectively. This is probably because the competing inter-
molecular interactions such as hydrogen bondings [2.900(4) Å]
and CH–π interactions (2.980 Å) were formed instead of auro-
philic interaction.
Bidentate arsenic ligands were synthesized following the litera-
ture procedure (Scheme 2).[12,13] Diphenylarsanyllithium
(Ph2AsLi) was generated from hexaphenylhexaarsine (As6Ph6)
and phenyllithium (PhLi). Without isolation, the solution of
Ph2AsLi was utilized for the substitution reaction with alkyl,
vinyl, or aryl dichlorides to give corresponding bidentate li-
gands. The newly synthesized ligands, trans-dpav and dpapz,
were characterized by NMR spectroscopy, high resolution mass
analysis, and single-crystal X-ray diffraction analysis.
Figure 1. Results of X-ray crystallography of Au2Cl2(dpab). (a) Intramolecular
Au···Au distance. (b) Intermolecular Au···Au distance and selected intermolec-
ular interactions such as hydrogen bond and CH–π interaction. Red dot rep-
resents the centroid of the benzene ring.
Intermolecular aurophilic interactions were observed for the
ligands with flexible linkers such as dpae and dpap, and they
offered polymorphs to their Au2Cl2(diars) complexes. The crystal
polymorphs of Au2Cl2(dpae) was reported by the Balch's group;
Scheme 2. Syntheses of bidentate arsenic ligands. The isolated yields of dpae,
dpap, dpab, cis-dpav, and dpaq were cited from previous papers.[12,13]
The gold(I) metalation of the diarsine ligands afforded ad- the space groups of the crystals that they obtained were P21/c
duct complexes Au2Cl2(diars). The coordination was confirmed and P1.[3a] On the other hand, the results of our present analy-
¯
by NMR spectroscopy; the signals were shifted to lower mag- ses showed P21/c [α-Au2Cl2(dpae)] and C2/c [ꢀ-Au2Cl2(dpae)]
netic field because of lowering the electron density by the coor- space groups. While the formar corresponds to the Balch's re-
dination. The obtained complexes were recrystallized by slow port, the latter should be the third polymorphic form. The pack-
mixing of a solution (dichloromethane or chloroform) and poor ing structures of α- and ꢀ-Au2Cl2(dpae) were completely differ-
solvent (methanol or hexane). The ligands with flexible linker, ent. In the α-form, dimerization occurred via intermolecular
i.e., dpae, and dpap, tended to give polymorphs, whereas only aurophilic interactions (Figure 2a), while 1D-polymers were
one type of crystalline structure was obtained in the cases of formed in the ꢀ-one (Figure 2b). On the other hand,
those with rigid one.
α-Au2Cl2(dpap) (space group: P21/c) and ꢀ-Au2Cl2(dpap) (space
group: Pbcn) were composed of 1D-polymers through inter-
molecular aurophilic interactions with similar bond lengths,
bond angles, and torsion angles (Figure 2c and Figure 2d).
The complexes with the rigid ligands did not show crystal
The single crystals were fabricated for X-ray diffraction (XRD)
analysis. The results of the analyses are summarized in Table 1.
The gold(I) formed linear coordination considering the wide
As–Au–Cl angles [> 171.9(2)°]. There are negligible differences
in coordination bond lengths for Au–As and Au–Cl, implying polymorphs in contrast to those with flexible ones. (Figure 3).
that coordination abilities including σ-donation and π-accept- The cis- or ortho-linked ligands, i.e., cis-dpav, dpapz, and dpaq,
Table 1. Selected bond length [Å] and angles [°] of Au2Cl2(diars) complexes.
Ligand
Space group
Au···Au intra
Au···Au Inter
Au–As
Au–Cl
2.291(3), 2.273(3) 176.03(7), 172.42(8)
2.291(3) 172.47(6)
2.294(3), 2.286(4) 176.9(1), 173.96(9)
2.285(2), 2.277(3) 175.05(7), 173.43(6)
As–Au–Cl
As–Au···Au–Cl
dpae (α)
dpae (ꢀ)
dpap (α)
dpap (ꢀ)
dpab
cis-dpav
trans-dpav
dpapz
P21/c
C2/c
P21/c
Pbcn
C2/c
Cc
Pbcn
P21/n
P1
¯
–
–
–
–
3.129(2)
3.162(3)
3.275(1)
3.256(1)
–
2.335(2), 2.333(1)
2.344(2)
2.356(2), 2.340(2)
2.344(1), 2.338(1)
2.343(1)
2.337(2), 2.329(3)
2.342(1)
2.343(1), 2.340(1)
2.3352(7), 2.3290(7)
97.68(3)
116.07(3)
119.61(5)
117.49(3)
–
–
2.279(4)
2.312(8), 2.291(8) 173.7(2), 171.9(2)
2.290(2) 176.59(6)
175.6(1)
3.079(1)
–
2.965(1)
2.9784(5)
–
50.6(1)
3.025(1)
94.88(3)
60.62(2)
63.13(2)
2.283(2), 2.280(2) 175.92(5), 174.04(5)
2.274(2), 2.259(2) 172.86(6), 172.79(5)
dpaq
–
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Figure 3. Results of X-ray crystallography of (a) Au2Cl2(cis-dpav), (b)
Au2Cl2(trans-dpae), (c) Au2Cl2(dpapz), and (d) Au2Cl2(dpaq). Intra- and inter-
molecular Au···Au distances are displayed.
Figure 2. Results of X-ray crystallography of (a) α-Au2Cl2(dpae), (b) ꢀ-
Au2Cl2(dpae), (c) α-Au2Cl2(dpap), and (d) ꢀ-Au2Cl2(dpap). Intermolecular
Au···Au distances are displayed.
ples were prepared by grinding crystalline ones in a mortar. In
addition, the PL spectra of the bare ligands were also measured
for understanding the origins of the emissions (Figure S15).
Initially, we investigated Au2Cl2(dpae) (Figure 4a and 4b). In
supported intramolecular aurophilic interactions because the
coordination directions of the ligands were fixed by the vinyl-
ene or arylene linkers. The Au···Au distances of the complexes the α-form, the HE emission of Au2Cl2(dpae) at 77 K was ob-
were similar to each other; Au2Cl2(cis-dpav): 3.079(1) Å, served around 489 nm, while the LE emission appeared around
Au2Cl2(dpapz): 2.965(1) Å, and Au2Cl2(dpaq): 2.9784(5) Å. On the 723 nm at room temperature (Figure 4a). On the other hand, ꢀ-
3
other hand, 1D-polymer was formed for Au2Cl2(trans-dpav) via Au2Cl2(dpae) showed dual emission due to the ππ* (485 nm)
intermolecular aurophilic interactions. The Au···Au distance and 3(X+M)C/3XLCT (700–770 nm) excitation states except for
[3.025(1) Å] was similar to those of other complexes with the the ground sample at room temperature (Figure 4b). It is known
rigid ligands.
that Cl–Au···Au–Cl torsion angle as well as Au···Au bond length
affect the photophysical properties of aurophilic interaction.[7]
Although the Au···Au bond lengths of α- and ꢀ-Au2Cl2(dpae)
are similar [3.129(2) and 3.162(3) Å, respectively], their
Cl–Au···Au–Cl torsion angles were different [α-form: 100.3(1)°,
ꢀ-form: 114.67(8)°], which possibly caused the different emis-
sion behaviors. Then after grinding, the LE emissions were en-
hanced for both the α- and ꢀ-forms at room temperature. Negli-
gible spectral change occurred after grinding the crystal sample
of the bare ligand, thus the HE emission was not affected by
the grinding procedure (Figure S15a). The powder XRD (PXRD)
measurements revealed that the grinding caused crystal-to-
amorphous transitions (Figure S14a and Figure S14b). For
Au2Cl2(dpae), aurophilic interactions might be readily formed
in the amorphous states in contrast to the conformationally
restricted crystal phases.
We then examined photoluminescence (PL) properties of the
obtained Au2Cl2(diars) complexes in the solid-states. Generally,
origins of emission of dinuclear gold(I) complexes are classified
into two triplet excitation states. In reference to the detailed
discussion on Au2I2 complexes with diphosphine ligands,[14] the
low-energy (LE) one has contribution of halide and metal-cen-
tered and halide-to-ligand charge transfer [3(X+M)C/3XLCT] ex-
citation states, and the high-energy (HE) emission is attributed
3
to intraligand ππ* excitation state. There is energy barrier for
internal conversion form the 3ππ* excitation state to the
3(X+M)C/3XLCT one. Accordingly, the HE emission is favorable at
lower temperature, while the LE emission is favorable at higher
temperature. It is notable that energy level of the 3(X+M)C/
3XLCT excitation state is affected by the Au···Au distance, mean-
ing that mechanical stimuli such as grinding can change color
of the LE emission. It has been reported that through crystal-
Although polymorphism was also observed for Au2Cl2(dpap),
to-amorphous transition, HE emission is weakened and LE one sufficient amounts of the ꢀ-form crystals for PL measurement
is enhanced gradually as grinding time is longer.[15] Herein, the were not collected. We thus analyzed only the α-form (Fig-
PL spectra were measured at room temperature and 77 K for ure 4c). The emission of the crystalline sample at 77 K was
the crystalline and amorphous samples; the amorphous sam- derived from the 3ππ* excitation state, whereas the emission
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Figure 4. PL spectra of AuCl complexes in the solid states. The data of the non-emissive samples were omitted for clarity.
3
due to the XLCT was dominant at room temperature. This result internal conversion of ππ*-to-3(X+M)C/3XLCT when compared
indicates that the energy barrier from ππ* to (X+M)C/3XLCT with dpapz.
of Au2Cl2(dpap) was lower than that of Au2Cl2(dpae). After
grinding, the emission due to the XLCT was observed at
3
3
Conclusion
room temperature likely to α-Au2Cl2(dpae). In the case of
Au2Cl2(dpab) (Figure 4d), the emission in the crystalline state
Diarsenic ligands were prepared by practical synthetic method
was only HE one because there is no aurophilic interaction in
reference to the X-ray crystallographic data. On the other hand,
the LE emission was observed after grinding whether at room
temperature and 77 K. This is probably because the grinding
assisted the formation of aurophilic interactions via crystal-to-
amorphous transition, though the PXRD indicated that crystals
remained to some extent even after grinding (Figure S14d).
The emission of Au2Cl2(cis-dpav) and Au2Cl2(trans-dpav) was
not observed in the crystalline state at room temperature (Fig-
ure 4e and Figure 4f). The reason for the negligible emission is
still unclear, but it is possible that molecular motions were not
fully restricted at room temperature to cause non-emissive de-
activation of the excitons. This hypothesis was supported by
the fact that the LE emission was observed in the crystalline
state at 77 K, implying that the molecular motions were frozen
by cooling. PXRD measurements revealed that grinding in a
mortar cannot cause crystal-to-amorphous transition for
Au2Cl2(cis-dpav) and Au2Cl2(trans-dpav); sharp signals due to
crystals were still observed after grinding for several minutes
(Figures S14e and S14f). Therefore, the emission properties
were not changed by grinding.
that we have recently developed. The Au2Cl2 complexes with
the diarsenic ligands were synthesized, and their structures
were analyzed by X-ray crystallography. The diarsenic ligands
worked as templates for construction of intra- or intermolecular
aurophilic interaction except for dpab. The flexible ligands such
as dpae and dpap produced crystal polymorphs of the resultant
Au2Cl2(diars) complexes. The rigid ligands cis-dpav, dpapz, and
dpaq supported intramolecular aurophilic interaction while
Au2Cl2(trans-dpav) formed 1D-polymeric structure; their coordi-
nation directions were fixed by the vinylene or arylene linkers.
The emission behaviors were drastically changed according to
3
the ligand structures. The 3ππ* and (X+M)C/3XLCT excitation
states, being responsible for the emissions, were affected by
π-conjugation, Au···Au distance and torsion, rigidity, and molec-
ular packing, resulting in stimuli-responsiveness of the com-
plexes: luminescent mechanochromism and/or thermochro-
mism. The present study on arsenic-gold complexes will open
new venue towards the further development of other metal
complexes with various functions. The relationships between
arsenic ligand structure and photophysical properties in other
metal complexes are now under investigation.
For the crystal samples of Au2Cl2(dpapz) (Figure 4g) and
Au2Cl2(dpaq) (Figure 4h), no emission was observed at room
temperature likely to Au2Cl2(cis-dpav) and Au2Cl2(trans-dpav),
but only the HE emissions were observed at 77 K. Pyrazine and
quinoxaline moieties had more expanded π-conjugated sys-
tems than the vinylene moieties of cis- and trans-dpav, resulting
in the stabilized IL states to give higher energy barrier from
3ππ* to 3(X+M)C/3XLCT. Moreover, after grinding, Au2Cl2(dpapz)
showed the LE emission was exhibited even at 77 K, whereas
Au2Cl2(dpaq) showed the LE and HE emissions at room temper-
ature and 77 K, respectively. This is because the more expanded
Experimental Section
Materials
Chloroform (CHCl3), dichloromethane (CH2Cl2), tetrahydrofuran
(THF), methanol (MeOH), 1,2-dichloroethane, sodium sulfate
(Na2SO4), 2-propanol and cis-1,2-dichloroethylene were purchased
from Nacalai Tesque, Inc. Hexane was purchased from Wako Pure
Chemical Industry, Ltd. Phenyllithium (PhLi, 1.1
and diethyl ether) was purchased from Kanto Chemical Co., Inc. 1,3-
Dichloropropane, 1,4-dichlorobutane, 2,3-dichloropyrazine, and 2,3-
M in cyclohexane
π-conjugation of dpaq further raised the energy barrier for the dichloroquinoxaline were purchased from Tokyo Chemical Industry
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Co., Ltd. trans-1,2-dichloroethylene and gold(I) chloride (AuCl) were
H), 7.06 (s, 2H) ppm; 13C-NMR (CDCl3, 100 MHz): δ = 145.43, 140.22,
purchased from Sigma Aldrich. Hexaphenylcyclohexaarsine 133.25, 128.69, 128.48 ppm. HR-MS (FAB) m/z: calculated for
(Ph6As6)[9b] and arsenic ligands dpae,[12] dpap,[13] dpab,[13] cis-
dpav,[12] and dpaq[13] were prepared according to literature proce-
dures.
C26H22As2: 484.0153; found [M]+: 484.0148.
dpapz: A THF (30 mL) dispersion of Ph6As6 (500 mg, 0.548 mmol)
was cooled to 0 °C under N2 atmosphere, and PhLi (1.10
M in cyclo-
Measurement
hexane and Et2O, 3.0 mL, 3.30 mmol) was slowly added. The reac-
tion mixture was warmed to room temperature and stirred for 2 h.
Again, the reaction mixture was cooled to 0 °C, and a THF solution
(5 mL) of 1,2-dichloropyrazine (244 mg, 1.64 mmol) was slowly
added. After stirring at room temperature overnight, the reaction
was quenched by distilled water. The resultant solution was ex-
tracted with CH2Cl2 three times, and the combined organic layers
were dried with Na2SO4. After filtration, the volatiles were removed
in vacuo. The obtained products were purified by recrystallization
from CH2Cl2/MeOH to obtain colorless solid of dpapz (361 mg,
1H (400 MHz) and 13C (100 MHz) nuclear magnetic resonance (NMR)
spectra were recorded on a Bruker AVANCE III 400 NMR spectrome-
ter. High resolution mass spectra (HRMS) were obtained on a JEOL
JMS-SX102A spectrometer. Emission and excitation spectra were
obtained on an FP-8500 (JASCO) spectrometer and the absolute PL
quantum yields (Φ) were determined by using a JASCO ILFC-847S;
the quantum yield of quinine sulfate as reference was 0.52, which
is in agreement with the literature value.[16] Powder X-ray diffrac-
tometry (XRD) studies were performed on a Rigaku Smartlab X-ray
diffractometer with CuKα radiation (λ = 1.5406 Å) in the 2θ/θ mode
at room temperature. The 2θ scan data were collected at 0.01° inter-
vals and the scan speed was 10° (2θ) / min.
1
0.673 mmol, 41 %). H-NMR ([D6]Acetone, 400 MHz): δ = 8.55 (s, 2
H), 7.34–7.21 (m, 20 H) ppm; 13C-NMR (CDCl3, 100 MHz): δ = 168.52,
144.84, 139.02, 134.34, 128.76, 128.65 ppm. HR-MS (FAB) m/z: calcu-
lated for C28H22As2N2: 536.0215; found [M]+: 536.0226.
X-ray Crystallographic Data for Single Crystalline Products
General Procedure for Gold(I) Chloride Complexes: A CH2Cl2 so-
lution of arsenic ligands and AuCl was stirred under a N2 atmos-
phere at room temperature for 2 h. After filtration with a membrane
filter, recrystallization gave crystals of AuCl complexes.
The single crystal was mounted on a nylon loop. Intensity data
were collected at room temperature on a Rigaku XtaLAB mini with
graphite-monochromated MoKα radiation. The readout was per-
formed in the 0.073 mm pixel mode. The data were collected at
room temperature to a maximum 2θ value of 55.0°. Data were proc-
essed by Crystal Clear.[17] An empirical absorption correction[18] was
applied. The data were corrected for Lorentz and polarization ef-
fects. The structure was solved by direct methods[19] and expanded
by using Fourier techniques. The non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were refined by using the riding
model. The final cycle of the full-matrix least-squares refinement
on F2 was based on observed reflections and variable parameters.
All calculations were performed by using the CrystalStruc-
ture[19] crystallographic software package except for the refine-
ment, which was performed by using SHELXL2013.[20] The disor-
Au2Cl2(dpae):
A CH2Cl2 solution (10 mL) of dpae (49 mg,
0.10 mmol) and AuCl (50 mg, 0.22 mmol) was used to obtain color-
less solid of Au2Cl2(dpae) (69 mg, 0.073 mmol, 73 %). Recrystalliza-
tion: slow evaporation of CH2Cl2 for α-form, slow diffusion to mix
MeOH with a CH2Cl2 solution for ꢀ-form. 1H-NMR spectrum well
corresponded to literature data.[3a]
Au2Cl2(dpap):
A CH2Cl2 solution (10 mL) of dpap (99 mg,
0.20 mmol) and AuCl (94 mg, 0.40 mmol) was used to obtain color-
less solid of Au2Cl2(dpap) (140 mg, 0.145 mmol, 73 %). Recrystalliza-
tion: slow diffusion to mix MeOH with a CH2Cl2 solution. 1H-NMR
(CDCl3, 400 MHz): δ = 7.61–7.45 (m, 20 H), 2.76 (t, J = 7.4 Hz, 4 H),
2.05 (quint, J = 7.4 Hz, 2 H) ppm; 13C-NMR (CDCl3, 100 MHz): δ =
132.7 131.7, 130.4, 129.9 28.5, 21.6 ppm.
dered structures were refined with SHELXL2016[21] by using
[22]
Olex2
as the graphical interface. Crystal data and more informa-
tion on the X-ray data collection are summarized in Table 1 and S1–
S14.
Au2Cl2(dpab): A CH2Cl2 solution (10 mL) of dpap (299 mg,
0.582 mmol) and AuCl (274 mg, 1.18 mmol) was used to obtain
colorless solid of Au2Cl2(dpab) (398 mg, 0.406 mmol, 70 %). Recrys-
Deposition Numbers 2034893 (for trans-dpav), 2034892 (for dpapz),
2017062 [for α-Au2Cl2(dpae)], 2017060 [for ꢀ-Au2Cl2(dpae)],
2017061 [for α-Au2Cl2(dpap)], 2017063 [for ꢀ-Au2Cl2(dpap)],
2017059 [for Au2Cl2(dpab)], 2017058 [for Au2Cl2(cis-dpav)], 2017065
[for Au2Cl2(trans-dpav)], 2017064 [for Au2Cl2(dpapz)], 2017066 [for
Au2Cl2(dpaq)] contain the supplementary crystallographic data for
this paper. These data are provided free of charge by the joint Cam-
bridge Crystallographic Data Centre and Fachinformationszentrum
Karlsruhe Access Structures service www.ccdc.cam.ac.uk/structures.
1
tallization: slow diffusion to mix MeOH with a CH2Cl2 solution. H-
NMR (CDCl3, 400 MHz): δ = 7.58–7.45 (m, 20 H), 2.44 (t, J = 7.4 Hz,
4 H), 1.80 (quint, J = 3.9 Hz, 4 H) ppm; 13C-NMR (CDCl3, 100 MHz):
δ = 132.6, 131.6, 131.0, 129.8, 27.7, 27.4 ppm.
Au2Cl2(cis-dpav): A CH2Cl2 solution (10 mL) of cis-dpav (485 mg,
0.100 mmol) and AuCl (476 mg, 2.04 mmol) was used to obtain
colorless solid of Au2Cl2(cis-dpav) (533 mg, 0.562 mmol, 56 %). Re-
crystallization: slow diffusion to mix hexane with a CH2Cl2 solution.
1H-NMR (CDCl3, 400 MHz): δ = 7.62 (s, 2 H), 7.57–7.41 (m, 20 H)
ppm; 13C-NMR (CDCl3, 100 MHz): δ = 142.4, 132.8, 131.9, 131.2,
130.0 ppm.
Synthesis
trans-dpav:
0.574 mmol) was cooled to 0 °C under N2 atmosphere, and PhLi
(1.12 in cyclohexane and Et2O, 3.1 mL, 3.47 mmol) was slowly
A THF (20 mL) dispersion of Ph6As6 (524 mg,
M
Au2Cl2(trans-dpav): A CH2Cl2 solution (10 mL) of trans-dpav
(25 mg, 0.050 mmol) and AuCl (24 mg, 0.10 mmol) was used to
obtain colorless solid of Au2Cl2(trans-dpav) (32 mg, 0.030 mmol,
65 %). After the reaction, colorless precipitates were collected and
purified by recrystallization: (slow diffusion to mix hexane with a
CHCl3 solution). 1H-NMR (CDCl3, 400 MHz): δ = 7.59–7.51 (m, 20 H),
7.36 (s, 2H) ppm. 13C-NMR cannot be measured because of the low
solubility.
added. The reaction mixture was warmed to room temperature and
stirred for 2 h. Again, the reaction mixture was cooled to 0 °C, and
trans-1,2-dichloroethylene (130 μL, 1.71 mmol) was slowly added.
After stirring at room temperature overnight, the reaction was
quenched by distilled water. The resultant solution was extracted
with CH2Cl2 three times, and the combined organic layers were
dried with Na2SO4. After filtration, the volatiles were removed in
vacuo. The obtained products were purified by recrystallization
from CH2Cl2/MeOH to obtain colorless solid of trans-dpav (0.1648 g,
Au2Cl2(dpapz): A CH2Cl2 solution (20 mL) of dpapz (80 mg,
0.150 mmol) and AuCl (70 mg, 0.30 mmol) was used to obtain color-
1
0.340 mmol, 20 %). H-NMR (CDCl3, 400 MHz): δ = 7.40–7.30 (m, 20
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Full Paper
doi.org/10.1002/ejic.202000810
EurJIC
European Journal of Inorganic Chemistry
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less solid of Au2Cl2(dpapz) (90 mg, 0.090 mmol, 60 %). Recrystalliza-
tion: slow diffusion to mix MeOH with a CH2Cl2 solution. 1H-NMR
(CDCl3, 400 MHz): δ = 8.71 (s, 2 H), 7.60–7.58 (m, 8 H), 7.52–7.48 (m,
4 H), 7.44–7.40(m, 8 H). 13C-NMR cannot be measured because of
the low solubility.
Au2Cl2(dpaq):
A CH2Cl2 solution (20 mL) of dpaq (80 mg,
0.140 mmol) and AuCl (64 mg, 0.28 mmol) was used to obtain yel-
low solid of Au2Cl2(dpaq) (69 mg, 0.066 mmol, 48 %). Recrystalliza-
tion: slow diffusion to mix MeOH with a CH2Cl2 solution. 1H-NMR
(CDCl3, 400 MHz): δ = 8.02–8.00 (m, 2H), 7.89–7.86 (m, 2H), 7.64 (d,
J = 8 Hz, 8H), 7.48 (t, J = 6 Hz, 4H), 7.41 (t, J = 8 Hz, 8H). 13C-NMR
cannot be measured because of the low solubility.
Acknowledgments
This work was supported by JSPS KAKENHI, grant Number
19H04577 (Coordination Asymmetry) and 20H02812 [Grant-in-
Aid for Scientific Research (B)] to H. I.
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Keywords: Diarsine ligands · Gold · Aurophilicity ·
Mechanochromic luminescence · Thermochromic
luminescence
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Received: August 27, 2020
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