Synthesis, Characterization, and Catalytic Activities of Palladium Complexes with Phenylene-Bridged Bis(thione) Ligands

Article abstract of DOI:10.1021/acs.organomet.9b00051

The neutral phenylene-bridged bis(thione) compounds, 1,3-bis(3′-ethylimidazolyl-2′-thione)benzene (Betb), 1,3-bis(3′-butylimidazolyl-2′-thione)benzene (Bbtb), and 1,3-bis(3′-allylimidazolyl-2′-thione)benzene (Batb), have been synthesized and characterized. Reactions of palladium precursor PdCl₂(CH₃CN)₂ with phenylene-bridged bis(thione) ligands in 1:2 ratio resulted in the formation of the complexes: PdCl₂(L)₂ (L = Betb, 3a; L = Bbtb, 3b; L = Batb, 3c, respectively). In contrast, treatment of the ligands with PdCl₂(CH₃CN)₂ in 1:1 ratio gave cyclometalation palladium complexes Pd²⁺Cl(L^-) (L = Betb-H, 4a; L = Bbtb-H, 4b; L = Batb-H, 4c) through the metal-induced C-H activation. Complexes 4a-c can also be obtained by the reaction of bis(thione) ligands and PdCl₂ in 1:1 ratio. The reaction of 3a-c with additional PdCl₂(CH₃CN)₂ also afforded complexes 4a-c. All ligands and palladium complexes were fully characterized by one-/two-dimensional NMR spectra, mass spectrometry, and infrared spectrometry. And the molecular structures of 3a-c, 4a, and 4c have been determined by the single-crystal X-ray diffraction method. Furthermore, the detailed spectroscopic properties and catalytic activities of the complexes for the reduction of nitro compounds were discussed in terms of the modification of the coordination ligands to the center metal.

Full text of DOI:10.1021/acs.organomet.9b00051

Article
pubs.acs.org/Organometallics
Cite This: Organometallics XXXX, XXX, XXX−XXX
Synthesis, Characterization, and Catalytic Activities of Palladium
Complexes with Phenylene-Bridged Bis(thione) Ligands
,
†
†
†
‡
,‡
Wei-Guo Jia,* Li-Li Gao, Zhi-Bao Wang, Li-Ying Sun, and Ying-Feng Han*
†The Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Laboratory of Molecular-Based Materials (State
Key Laboratory Cultivation Base), College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241002, P. R.
China
‡
Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of Ministry of Education, College of Chemistry and
Materials Science, Northwest University, Xi’an 710127, P. R. China
*
S Supporting Information
ABSTRACT: The neutral phenylene-bridged bis(thione)
compounds, 1,3-bis(3′-ethylimidazolyl-2′-thione)benzene
(
Betb), 1,3-bis(3′-butylimidazolyl-2′-thione)benzene (Bbtb),
and 1,3-bis(3′-allylimidazolyl-2′-thione)benzene (Batb), have
been synthesized and characterized. Reactions of palladium
precursor PdCl (CH CN) with phenylene-bridged bis-
2
3
2
(
thione) ligands in 1:2 ratio resulted in the formation of the
complexes: PdCl (L) (L = Betb, 3a; L = Bbtb, 3b; L = Batb,
2
2
3
c, respectively). In contrast, treatment of the ligands with
2
+
−
PdCl (CH CN) in 1:1 ratio gave cyclometalation palladium complexes Pd Cl(L ) (L = Betb-H, 4a; L = Bbtb-H, 4b; L =
2
3
2
Batb-H, 4c) through the metal-induced C−H activation. Complexes 4a−c can also be obtained by the reaction of bis(thione)
ligands and PdCl in 1:1 ratio. The reaction of 3a−c with additional PdCl (CH CN) also afforded complexes 4a−c. All ligands
2
2
3
2
and palladium complexes were fully characterized by one-/two-dimensional NMR spectra, mass spectrometry, and infrared
spectrometry. And the molecular structures of 3a−c, 4a, and 4c have been determined by the single-crystal X-ray diffraction
method. Furthermore, the detailed spectroscopic properties and catalytic activities of the complexes for the reduction of nitro
compounds were discussed in terms of the modification of the coordination ligands to the center metal.
INTRODUCTION
thione ligands are also highly effective catalysts in the
construction of C−C and C−heteroatom bonds under mild
condition. The synthesis of palladium complexes containing
thione ligands has attracted considerable attention due to their
extensive application in organic synthetic chemistry. Therefore,
exploring the reactivity of palladium complexes with thione
ligands would be interesting.
■
Imidazoline-2-chalcogenone ligands NHCE (NHC = N-
heterocyclic carbene, E = S, Se) and their transition-metal
complexes play a crucial role in organometallic and
coordination chemistry as well as in catalysis.
-chalcogenone ligands are good σ-donors and weak π-
acceptors and can be easily modified using appropriate
available NHC precursors to allow fine tuning of steric and
electronic properties of the center metal complexes. A series of
transition-metal complexes with imidazoline-2-chalcogenone
ligands have been synthesized for various applications such as
1
−9
Imidazoline-
2
Anilines and their derivatives are important intermediates in
organic synthesis, and the development of efficient and
environmentally benign protocols for nitro group reduction
3
1
is still highly desirable. Apart from hydrogen, sodium
2
,10,11
12
borohydride (NaBH ) reducing agent has been widely used,
4
C−C bond formation,
borylation of alkynes, biomi-
1
3
14,15
allowing efficient reduction of nitroarenes to anilines when
metic activity, and hydrogen transfer reaction
in recent
32
used in combination with metal catalysts. Palladium-based
catalysts, both coordination complexes and supported by
polymer, metal−organic framework, nanohybrid, or nano-
particles, are all good candidates for the hydrogenation of
years. And the catalytic performance of these catalysts is
comparable with those of the efficient metal−NHC complexes
for organic transformation.
In our previous studies, we synthesized transition-metal
complexes including Ir, Rh,
10,16
33−39
17−21
22
23
24
nitroarenes due to their efficient catalytic performance.
Au, Zn, Ni, and Co
However, there are few reports on palladium complexes
bearing thione ligands for the reduction of nitro compounds.
Continuing our research interests in organochalcogen metal
complexes for their rich chemistry, we prepared palladium−
based on thione ligands and studied their diverse coordination
network architectures and application in organometallic
transformations, olefin polymerization, and nitroarene reduc-
tion reactions. Palladium complexes are versatile catalysts in
various catalytic reactions, including C−H bond functionaliza-
tion, C−C and C−heteroatom bond formation, and olefin
Received: January 24, 2019
2
5−30
polymerization.
The palladium complexes containing
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
thione complexes to study their versatile structural chemistry
and catalytic activities. Herein, we report an efficient method
to synthesize a series of phenylene-bridged bis(thione) ligands
and the corresponding Pd(II) complexes. We also probe their
catalytic activity toward reduction of nitro compounds, and a
bid to understand substituent group effects of the ligands. This
is the first report, to the best of our knowledge, investigating
isolated by filtration and fully characterized by IR, NMR
spectroscopy, mass spectrometry, and X-ray crystallography.
The proton signal of the 2-position on the benzene ring
1
observed in 2a at δ = 7.90 ppm was absent in the H NMR of
4a, suggesting a C−Pd bond in place of a C−H. We also saw a
downfield shift for the doublet at 6.84 and 6.98 ppm to 7.93
and 7.66 ppm for imidazole proton in comparison to 2a. For
1
Pd(II)−phenylene-bridged bis(thione) complexes for NO
reduction catalysis.
3a, the imidazolium proton H NMR shifted downfield to 7.89
2
1
3
and 7.60. Furthermore, C NMR spectrum of 4a and 3a
showed characteristic resonance for the thiocarbonyl C at δ =
RESULTS AND DISCUSSION
As outlined in Scheme 1, phenylene-bridged bis(thione)
compounds (2a−c) were easily synthesized in one-pot via
1
51.61 ppm (4a) and 154.55 ppm (3a), significantly shifted
■
upfield versus the Cimidazole resonance of 2a, where δ = 162.72
ppm, in agreement with the palladium complex reported.
41
The electrospray ionization mass spectra (ESI-MS) of the
Scheme 1. Synthesis of Phenylene-Bridged Bis(thione)
Compounds (2a−c)
complexes showed peaks at m/z = 383.0489 and 803.0659 for
2
+
3a and 434.9937 for 4a, and these are assigned to [M − 2Cl]
+
and [M − Cl] ions, respectively.
Single crystals of 3a, 3b, 3c, 4a, and 4c suitable for X-ray
diffraction studies were grown by slow diffusion of diethyl
ether into a concentrated solution of the complexes in
CH Cl /MeOH (v/v = 1:1) solvent mixture. The crystallo-
2
2
graphic data for palladium complexes are summarized in Table
S1, and selected bond lengths and angles are shown in Table 1.
Table 1. Selected Bond Lengths (Å) and Bond Angles (deg)
the reactions of 1,3-bis(3′-alkylimidazolyl-1′-yl)benzene di-
for 3a−c, 4a, and 4c
bromide with sulfur powder in the presence of K CO with
2
3
3
a
3b
3c
methanol as a solvent in moderate yields according to literature
4
0−42
Pd(1)−S(2)
Pd(1)−S(2′)
Pd(1)−S(1′)
Pd(1)−S(1)
S(1)−C(1)
S(2)−C(10)
S(2)−Pd(1)−S(2′)
S(2)−Pd(1)−S(1′)
S(2′)−Pd(1)−S(1′)
S(2)−Pd(1)−S(1)
S(2′)−Pd(1)−S(1)
S(1′)−Pd(1)−S(1)
2.3620(9)
2.3620(10)
2.3525(9)
2.3525(9)
1.711(2)
1.716(2)
180.0
90.35(3)
89.65(3)
89.65(3)
90.35(3)
180.00(3)
2.3580(8)
2.3580(8)
2.3447(8)
2.3447(8)
1.716(3)
1.712(3)
180.00(4)
90.71(3)
89.29(3)
89.29(3)
90.71(3)
180.00(4)
2.3552(9)
2.3552(9)
2.3567(9)
2.3567(9)
1.711(3)
1.716(3)
180.000(11)
90.52(3)
89.48(3)
89.48(3)
90.52(3)
180.0
methods.
The quantitative yield of palladium complexes
4
a−c was obtained by reaction of PdCl with 1 equiv of the
2
phenylene-bridged bis(thione) ligands through direct C−H
bond activation of the phenyl ring in the absence of base in
CH OH at room temperature for 22 h (Scheme 2), whereas
3
Scheme 2. Synthesis of Palladium Complexes with
Phenylene-Bridged Bis(thione) Ligands
4
a
4c
Pd(1)−C(1)
Pd(1)−S(1)
Pd(1)−S(2)
Pd(1)−Cl(1)
2.002(2)
2.3160(6)
2.3046(6)
2.4085(6)
1.704(2)
89.43(6)
90.42(6)
177.60(2)
177.35(6)
91.68(2)
88.57(2)
2.008(4)
2.3192(12)
2.3089(11)
2.3935(11)
1.699(5)
90.60(11)
91.67(11)
176.27(4)
176.54(11)
88.78(5)
S(1)−C(7)
C(1)−Pd(1)−S(1)
C(1)−Pd(1)−S(2)
S(1)−Pd(1)−S(2)
C(1)−Pd(1)−Cl(1)
S(1)−Pd(1)−Cl(1)
S(2)−Pd(1)−Cl(1)
89.13(4)
Complexes 3a−c crystallize in the triclinic system with the
P1 space group. The crystal structures confirm the formation
of the complex PdCl (L) , with two Cl couteranions. In
complexes 3a−c (Figure 1), each Pd(II) center is square
planar (S(2)−Pd(1)−S(2′) 180°), coordinated with four
thione ligands through S atoms. All Pd(II) complexes contain
two 10-membered chelate rings formed by the coordination of
bis(thione) to the metal center. The molecule sits on a
crystallographic center of symmetry, the two benzene ring
parallel to each other, with phenylene-bridged bis(thione)
̅
−
2
2
4
b was obtained in 67% yield with PdCl (CH CN) as a
2
3
2
4
2
reactant. However, when the phenylene-bridged bis(thione)
ligands react with 0.5 equiv of PdCl (CH CN) , it afforded
2
3
2
PdCl (L) (3a−c) in high yields at room temperature for 0.5
2
2
h. Complexes 4a−c could be further obtained by adding
PdCl (CH CN) to 3. These palladium complexes were
2
3
2
obtained as air- and moisture-stable yellow solid. They were
B
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
sulfur atoms from thione ligand, commonly seen for four-
coordinated Pd(II) complexes. There is a C axis passing
2
through the chlorine, palladium, and C atoms of the central
ring in complex 4a and 4c. Both the molecular structures of
two Pd(II) complexes contains two 6,6-fused palladacycles in a
twisted rac-conformation. The Pd−S distances (2.3160(6) and
2
.3046(6) Å in 4a, and 2.3192(12) and 2.3089(11) Å in 4c)
are comparable to those of palladium(II) complexes containing
thione ligands.
43,45
Pd−C distances (2.002(2) Å in 4a and
aryl
2
.008(4) Å in 4c) were shorter than those of in CCC−
5,46,47
bis(NHC)−Pd(II)−Cl complex.
The C −Pd−Cl atom
aryl
are almost linear (177.37° for 4a and 176.54° for 4c), and the
difference in the C−S dihedral angle relative to the benzene
rings increasing from 3.13° in 4a to 4.42° in 4c indicates
greater sterics due to the ligands. The twist angle (Φ), defined
as the angle between the plane of the anchoring ring and
square plane containing the metal and its four directly attached
atoms in metal complexes, could be indicative of any steric
48−51
Figure 1. Molecular structures of complexes 3a−c. Hydrogen atoms
in both structures and the non-coordinating two chloride anions and
the two co-crystallized MeOH molecules are not shown.
effects,
and the Φ value of 43.18° for 4a greatly surpasses
the Φ = 37.89° found for 4c, suggesting greater steric.
The palladium complexes prepared in this work showed
similar absorption and emission spectra, and the complexes
were red-shifted in both absorption and emission when
compared to the ligands (Figures 3 and S43). The absorption
and emission maxima are listed in Table 2. Complexes 3a−c
showed strong absorptions over a broad range of ultraviolet
and visible spectra. The absorption spectra for these complexes
showed a strong resemblance with the related ligands (2a−c)
at wavelengths of 290 nm. The second ligand in complexes
ligands oriented in trans conformation. The Pd−S distances
(
2.3525(9) and 2.3620(10) Å in 3a, 2.3447(8) and 2.3580(8)
Å in 3b, and 2.3552(9) and 2.3567(9) Å in 3c) are consistent
with the reported values for thione-based Pd(II) complex.
43,44
The crystal packing was solved with monoclinic P2 /n space
1
groups for complexes 4a and 4c. As shown in Figure 2, the
3
a−c caused a slight bathochromic shift of the absorption
bands by 3−23 nm due to increased conjugation in the ligands.
New medium absorptions appeared at 420 nm for complexes
3
a−c. For palladium complexes, the absorption peak (420 nm)
are attributed to the metal-to-ligand charge transfer transitions,
whereas the peaks at 290 nm are assigned to the π−π*
transition processes involving the ligands.
Figure 2. Molecular structures of complexes 4a and 4c. Hydrogen
atoms in both structures and the non-coordinating chloride anion and
the one co-crystallized MeOH molecules are not shown.
To further understand the fluorescent properties of
palladium complexes, the emission spectrum and their lifetimes
were probed in both solution and in solid state (Table 2).
Upon excitation at 355 nm, the emission spectrum showed a
broad peak at 446 nm (3a), 447 nm (3b), and 450 nm (3c)
and at 430 nm for complexes 4a−c. The time-resolved
photoluminescence decay spectra of representative complexes
coordination geometry of the central palladium center can be
best described as a distorted square planar configuration with
one chlorine atom, one carbon atom of benzene, and two
Figure 3. Absorption (a) and emission spectra (b) of palladium complexes 3a−c and 4a−c (2 × 10−5 mol/L) in CH Cl /MeOH (v/v = 1:1) at
2
2
room temperature.
C
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 2. Electronic Absorption and Emission Data for Palladium Complexes
λ/nm (ε/10 , M cm−1
4
−1
)
λex/nm
τ1/ns
τ2/ns
τavg/ns
3
3
3
4
4
4
a
b
c
a
b
c
313 (5.0)
311 (5.4)
293 (5.1)
290 (2.5)
290 (2.1)
290 (2.4)
420 (1.3)
420 (1.3)
420 (0.7)
450
447
446
430
430
430
0.85 ± 0.02
0.73 ± 0.02
0.86 ± 0.02
1.71 ± 0.04
1.09 ± 0.02
0.86 ± 0.03
5.57 ± 0.42
4.06 ± 0.09
3.90 ± 0.23
15.27 ± 0.57
13.76 ± 0.76
5.01 ± 0.31
3.16
2.83
1.93
8.93
7.86
3.03
Figure 4. Fluorescence decay curves and the corresponding fits of palladium complexes 3a−c (a) and 4a−c (b) in the solid state.
3
and 4 were recorded (Figure 4). It has been shown that
complexes 4a with a C−Pd bond have much longer lifetimes
than the corresponding complexes 3a. The same behavior has
42
been observed in other palladium complexes. For complexes
, the proportion of the short-lived component is prolonged
3
from 3a to 3c as well as complexes 4, indicating that the
indirect recombination of excitons is promoted with the bulk
substituent on the imidazole ring because of reducing
conjugate effect. The lifetimes (τ ) decreased for complexes
avg
3
and 4, with the bulk substituent showing reduced charge
transfer ability.
The palladium complexes are effective catalysts for the
33
reduction of nitroarenes. Thus, we evaluated the catalytic
activity of palladium complexes for nitro group reduction
starting with p-nitrophenol and sodium borohydride (NaBH4)
to search for optimal reaction conditions. Initially, p-nitro-
−
4
Figure 5. Time profile of p-nitrophenol reduction catalyzed by
palladium complexes (3a−c and 4a−c).
phenol (1 × 10 mmol) and 10 equiv of NaBH were added
4
into a cuvette with 3 mL H O at room temperature for
2
continuous reaction monitoring. The desired product was
obtained in 98.3% conversion with catalyst 4b after 32 min
shorter reaction times as compared to dipalladium complexes
with 1 mol % in the presence of sodium borohydride.
(Figure 5). In the blank experiment, no desired product was
observed with the same conditions but in the absence of
palladium complex. The reactivity remained relatively un-
affected even as catalyst loading of 4b was reduced to 0.25 mol
In the following step, the scope of this protocol was
explored. The nitro group is chemoselectively reduced in the
presence of chlorine group with excellent yield (98%) without
dehalogenation (Table 3, entry 2). However, lower yields were
obtained with electron-donating group substituents on the
phenyl ring. Methyl substituents at the meta, ortho, or para
position gave the desired products with increased yields due to
the steric effect (Table 3, entries 5−7). For 4-nitro-
benzaldehyde, the −CHO group was reduced together with
the nitro group. Under the same reaction conditions, the
−NHCOMe group was unreactive (Table 3, entries 14 and
15). Notably, the nitro group in N-heterocyclic compound was
also suitable for this catalytic system, giving the desired
product in 87 and 90% yield, respectively (Table 3, entries 16
%
for 42 min. Reactivity and conversion improved to 96.5% by
increasing the catalyst loading to 2 mol % for 10 min (Figure
S44, Supporting Information). Better conversion was achieved
when ethanol was used as a solvent, which made the palladium
complex and substrates more soluble. As shown in Figure 6,
the complex 4b was the best catalyst for the reduction of p-
nitrophenol under standard condition. Compared with
previous studies using dipalladium complexes as catalysts for
nitroarene reduction, the normal-pressure hydrogen serves as a
33
reducing agent, avoiding the use of dangerous hydrogen. And
the complex 4b provided greater catalytic efficiency and
D
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 3. Screening of Substrates for Nitro Compound
,
a b
Reduction Catalyzed by Complex 4b
Figure 6. Screening of palladium complexes catalyst for p-nitrophenol
reduction. Reaction conditions: 1 × 10− mmol p-nitrophenol, 10
equiv NaBH , palladium catalyst (1 mol %), H O (3 mL), room
4
4
2
temperature, 30 min.
and 17). It should be noted that cyclohexylamine was not
obtained as the final product with nitrocyclohexane as starting
material. Two intermediates, cyclohexanone oxime and N-
cyclohexylhydroxylamine, were obtained in 14 and 86% yield
respectively. When the reaction extended to 6 h, no
cyclohexylamine was detected (Table 3, entry 18).
The palladium hydride was proposed as the catalytically
52
active species for the nitrobenzene reduction. In the reaction
mixture of nitrobenzene, small quantities of azobenzene (1%)
were observed as a side product. Further, direct palladium-
catalyzed reduction of azobenzene resulted only in 16%
conversion in 2 h, which accounts for 7% 1,2-diphenylhy-
drazine and 9% aniline. When N-phenylhydroxylamine was
used as the starting substrate, 97% of the desired product was
obtained. This led us to conclude that the direct reduction
path A is favored in the presence of the palladium catalytic
33,53,54
system (Scheme 3).
CONCLUSIONS
■
Six palladium(II) complexes with one or two phenylene-
bridged bis(thione) ligands were synthesized and fully
characterized. Spectroscopic and X-ray crystallographic studies
confirmed the molecular structures of all palladium complexes.
Spectroscopic studies revealed that the substituent group on
imidazole ring had little effect on the absorption spectrum of
palladium complexes. Incorporation of the π-extended
imidazole led to a bathochromic shift in the absorption by
replacing the coordination chlorine atom with phenylene-
bridged bis(thione) ligand. The Pd(II) complexes are highly
a
Reaction conditions: 0.1 mmol nitrobenzene, 0.4 mmol NaBH , 4b
4
b
(
1 mol %), EtOH (2 mL), room temperature, 2 h. The yields were
determined by gas chromatography−mass spectrometry (GC−MS).
Scheme 3. Postulated Mechanism of the Reduction of Nitro
Compounds with Palladium Complex
active toward nitro compounds reduction using NaBH a
4
reducing agent under mild reaction conditions.
EXPERIMENTAL SECTION
Materials and Measurements. All operations were carried out
under a pure nitrogen atmosphere using standard Schlenk techniques.
All solvents were purified and degassed by standard procedures. 1,3-
■
55
Bis(imidazol-1-yl)benzene was synthesized according to literature.
1
13
H (400 MHz) and C (100 MHz) NMR were recorded on Bruker
AV 400 spectrometer at room temperature. Chemical shifts (δ) are
given as parts per million (ppm) and refer to the shift of the hydrogen
or carbon atoms in the solvents used (CDCl , CD OD, or dimethyl
3
3
sulfoxide (DMSO)-d ). The following abbreviations were used for the
6
E
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
mL methanol as a solvent. The mixture was allowed to reflux for 24 h
and then the solvent was removed with a rotary evaporator. The
remaining solid was extracted with 2 × 30 mL CH Cl , which was
2
2
then filtered and rotary evaporated to give the corresponding product.
1,3-Bis(3′-ethylimidazolyl-2′-thione)benzene (Betb 2a). Yield:
1
1.95 g, 59%. H NMR (400 MHz, CDCl ): δ 7.90 (d, J = 2.0 Hz, 1H,
3
ArH), 7.70−7.68 (m, 2H, ArH), 7.59 (dd, J = 8.4, 7.2 Hz, 1H, ArH),
6.98 (d, J = 2.4 Hz, 2H, thione), 6.84 (d, J = 2.4 Hz, 2H, thione), 4.16
1
3
(q, J = 7.2 Hz, 4H, CH CH ), 1.43 (t, J = 7.2 Hz, 6H, CH ).
C
3
2
3
NMR (100 MHz, CDCl ): δ 162.72, 138.70, 129.63, 125.73, 124.08,
3
−
1
118.07, 117.05, 43.23, 14.17. IR (KBr cm ): 3174 (w), 3090 (s),
3067 (s), 2982 (m), 2936 (w), 1600 (s), 1493 (s), 1460 (s), 1399
(vs), 1294 (s), 1262 (s), 1151 (m), 1090 (m), 1036 (w), 882 (w),
796 (m), 699 (s), 664 (s).
1,3-Bis(3′-butylimidazolyl-2′-thione)benzene (Bbtb 2b). Yield:
1
2.67 g, 69%. H NMR (400 MHz, CDCl ): δ 7.89 (s, 1H, ArH),
3
7.69−7.67 (m, 2H, ArH), 7.58 (dd, J = 8.4, 7.2 Hz, 1H, ArH), 6.98 (d,
J = 2.0 Hz, 2H, thione), 6.82 (d, J = 2.4 Hz, 2H, thione), 4.09 (t, J =
7.2 Hz, 4H, NCH ), 1.84−1.76 (m, 4H, CH CH CH ), 1.46−1.37
2
3
2
2
−
1
(m, 4H, CH CH ), 0.97 (t, J = 7.2 Hz, 6H, CH ). IR (KBr cm ):
3
2
3
149 (s), 3083 (vs), 2956 (vs), 2934 (vs), 2870 (vs), 1604 (vs), 1571
I(t) =
∑
α exp(−t/τ)
i
i
i=1
(1)
The data of palladium complexes were successfully modeled using
double exponentials. The average lifetime was determined using the
following equation
1
,3-Bis(3′-allylimidazolyl-2′-thione)benzene (Batb 2c). Yield:
1
.58 g, 73%. H NMR (400 MHz, CDCl ): δ 7.92 (t, J = 2.0 Hz,
3
H, ArH), 7.71−7.69 (m, 2H, ArH), 7.60 (dd, J = 8.4, 7.2 Hz, 1H,
2
2
α τ + α τ
1
1
2 2
τavg
=
2
2
α τ + α τ
(2)
13
1
1
2 2
δ 163.20, 138.69, 131.69, 129.68, 125.68, 123.93, 119.76, 118.06,
In both equations, t is the time, τ is the lifetime, and α is the pre-
1
1
1
17.48, 50.48. H, H correlated spectroscopy (COSY) (400/400
exponential factor. The fast decay lifetime (τ ) originates from the
1
1
1
MHz, CDCl ): δ H/δ H 7.71/7.61 (ArH/ArH), 7.00/6.83 (thione/
radiative emission via the direct interband exciton recombination, and
3
thione), 6.03/5.36, 4.75 (CH CH/CH CH, NCH ), 5.36/4.75
the slower lifetime (τ ) is ascribed to the emission decay of the
2
2
2
2
1
13
5
8
(
CH CH/NCH ). H, C heteronuclear single quantum coher-
indirect recombination.
General Procedure for the Synthesis of Salts 1a−c.
2
2
1
13
4
2,59
ence (HSQC) (400/100 MHz, CDCl ): δ H/δ C 7.92/123.93
3
(
(
1
3
Ar−C), 7.71/125.68 (Ar−C), 7.60/129.68 (Ar−C), 7.70/118.06
Phenylene-bridged imidazolium salts 1a−c were synthesized by
dissolving 1,3-bis(imidazol-1-yl)benzene (1 equiv) in dimethylforma-
mide (5 mL) and the corresponding alkyl bromine compounds (3.0
equiv). The reaction mixtures were stirred at 110 °C for 6 h. The
white solids formed were filtered and washed with ethyl acetate and
diethyl ether to afford salts 1a−c.
thione), 6.83/117.48 (thione), 6.03/131.69 (CH CH), 5.36/
2
−
1
19.76 (CH CH), 4.75 /50.48 (CH ). IR (KBr cm ): 3164 (w),
2
2
082 (s), 2978 (w), 2918 (w), 1643 (w), 1601 (s), 1492 (s), 1441
(
(
s), 1395 (vs), 1296 (s), 1262 (s), 1181 (m), 1141 (m), 993 (m), 933
m), 891 (m), 804 (m), 714 (m).
General Procedure for the Synthesis of Palladium Com-
1
a: The reagents used are 1,3-bis(imidazol-1-yl)benzene (0.63 g, 3
1
pounds 3a−c. To a solution of corresponding thione ligands (0.2
mmol) and bromoethane (0.98 g, 9 mmol). Yield: 1.17 g, 91%. H
mmol) in MeOH (15 mL), PdCl (CH CN) (26.0 mg, 0.1 mmol)
NMR (400 MHz, DMSO-d ): δ 10.21 (s, 2H, NCHN), 8.56 (t, J =
2
3
2
6
was added and the mixture was kept at room temperature and stirred
for 0.5 h. The reaction mixture was concentrated to 2 and 10 mL of
2
.4 Hz, 2H, imidazole), 8.52 (t, J = 2.0 Hz, 1H, ArH), 8.16 (t, J = 1.6
Hz, 2H, imidazole), 8.07−8.05 (m, 2H, ArH), 7.98 (dd, J = 9.2, 7.6
Et O was added to yield solid of 3a−c.
Hz, 1H, ArH), 4.34 (q, J = 7.2 Hz, 4H, CH CH ), 1.56 (t, J = 7.2 Hz,
2
3
2
1
3a: Yield: 79.6 mg, 95%. H NMR (400 MHz, CD OD): δ 8.05 (s,
6
1
H, CH3). 13C NMR (100 MHz, DMSO-d ): δ 135.70, 135.57,
3
6
2
H, ArH), 7.93−7.89 (m, 6H, thione and ArH), 7.75 (dd, J = 8.0, 1.6
Hz, 4H, ArH), 7.60 (d, J = 2.4 Hz, 4H, thione), 4.07−3.98 (m, 4H,
NCH ), 3.92−3.83 (m, 4H, NCH ), 1.22 (t, J = 7.2 Hz, 12H, CH ).
31.90, 123.25, 122.32, 121.00, 115.48, 12.77.
1
b: The reagents used are 1,3-bis(imidazol-1-yl)benzene (0.63 g, 3
1
mmol) and 1-bromobutane (1.23 g, 9 mmol). Yield: 1.29 g, 89%. H
2
2
3
1
3
C NMR (100 MHz, CD OD): δ 154.55, 136.71, 132.02, 126.02,
NMR (400 MHz, DMSO-d ): δ 10.24 (s, 2H, NCHN), 8.57 (s, 2H,
3
6
1
13
1
22.24, 122.23, 121.18, 45.52, 14.40. H, C HSQC (400/100 MHz,
imidazole), 8.51 (s, 1H, ArH), 8.16 (s, 2H, imidazole), 8.06 (d, J = 8.0
Hz, 2H, ArH), 7.97 (dd, J = 8.4, 7.2 Hz, 1H, ArH), 4.31 (t, J = 7.2 Hz,
1
13
CD OD): δ H/δ C 8.05/122.24 (Ar−C), 7.93/132.02, 121.18
3
(
4
Ar−C, thione), 7.75/126.02 (Ar−C), 7.60/122.23 (thione), 4.07/
4
H, NCH ), 1.96−1.88 (m, 4H, CH CH CH ), 1.40−1.31 (m, 4H,
2
3
2
2
1 13
13
5.52 (NCH ), 3.92/45.52 (NCH ), 1.22/14.40 (CH ). H,
C
CH CH ), 0.95 (t, J = 7.2 Hz, 6H, CH ). C NMR (100 MHz,
2
2
3
3
2
3
heteronuclear multiple bond correlation (HMBC) (400/100 MHz,
DMSO-d ): δ 135.80, 135.68, 131.88, 123.56, 122.37, 121.07, 115.52,
6
1
13
CD OD): δ H/δ C 8.05/126.02 (ArH/Ar−C), 7.93/154.55,
3
1.02, 18.82, 13.30.
c: The reagents used are 1,3-bis(imidazol-1-yl)benzene (0.63 g, 3
3
1
136.71 (thione, ArH/CS, Ar−C), 7.75/126.02, 122.24 (ArH/Ar−
1
mmol) and allyl bromide (1.09 g, 9 mmol). Yield: 1.19 g, 88%. H
C, Ar−C), 7.60/154.55, 45.52 (thione/CS, Ar−C, NCH
2
). IR
−
1
NMR (400 MHz, DMSO-d ): δ 10.18 (s, 2H, NCHN), 8.57 (s, 2H,
(KBr cm ): 3155 (m), 3081 (m), 2977 (w), 2925 (w), 1607 (m),
1595 (w), 1497 (m), 1406 (m), 1350 (w), 1306 (m), 889 (w), 795
6
imidazole), 8.49 (s, 1H, ArH), 8.07 (t, J = 8.8 Hz, 4H, ArH and
imidazole), 7.97 (t, J = 8.0 Hz, 1H, ArH), 6.21−6.11 (m, 2H, CH 
(m), 690 (m). Anal. Calcd for C32
H N PdS Cl : C 45.85, H 4.33, N
36 8 4 2
2
CH), 5.44 (t, J = Hz, 4H, CH CH), 4.99 (d, J = 6.0 Hz, 4H,
13.37 found: C 45.77, H 4.46, N 13.29. ESI-MS m/z: calcd for
2
13
+
+
NCH ). C NMR (100 MHz, DMSO-d ): δ 135.92, 135.62, 131.86,
[C32
[C32
H
H
36
N
N
8
PdS
PdS
4
Cl] [M − Cl] 803.0673; found: 803.0659; calcd for
2
6
2
+
2+
1
31.07, 123.52, 122.56, 121.31, 120.96, 115.74, 51.48.
36
8
4
]
[M − 2Cl] 383.0491; found: 383.0489.
3b: Yield: 85.5 mg, 90%. H NMR (400 MHz, CD
1
General Procedure for the Preparation of Thione Ligands
OD): δ 8.05 (t,
3
1
9,20,42
2
a−c.
In a 100 mL round-bottomed flask fitted with a reflux
J = 2.0 Hz, 2H, ArH), 7.94−7.90 (m, 6H, thione and ArH), 7.71 (dd,
J = 8.0, 2.0 Hz, 4H, ArH), 7.63 (d, J = 2.0 Hz, 4H, thione), 4.02−3.95
(m, 4H, NCH ), 3.84−3.77 (m, 4H, NCH ), 1.68−1.48 (m, 8H,
condenser was placed the corresponding imidazolium salt (10 mmol),
sulfur powder (0.64 g, 20 mmol), K CO (2.76 g, 20 mmol), and 50
2
3
2
2
F
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
CH CH CH ), 1.41−1.32 (m, 8H, CH CH ), 1.22 (t, J = 7.2 Hz,
3H, ArH), 4.11 (t, J = 3.2 Hz, 4H, NCH ), 1.81−1.73 (m, 4H,
3
2
2
3
2
2
13
1
2H, CH ). C NMR (100 MHz, CD OD): δ 154.55, 136.71,
CH CH CH ), 1.38−1.29 (m, 4H, CH CH ), 0.93 (t, J = 7.2 Hz, 6H,
3
3
3
2
2
3
2
1
1
13
1
(
32.02, 126.02, 122.24, 122.23, 121.18, 45.52, 14.40. H, H COSY
400/400 MHz, CD OD): δ H/δ H 7.94/7.63 (thione/thione),
CH ). C NMR (100 MHz, DMSO-d ): δ 152.07, 138.79, 131.84,
3
6
1
1
125.98, 121.67, 120.68, 118.87, 48.06, 30.67, 19.06, 13.46. IR (KBr
3
−
1
7
.94/7.71 (ArH/ArH), 4.02/1.68 (NCH /CH CH CH ), 3.84/1.68
cm ): 3151 (m), 3110 (m), 3073 (s), 2961 (m), 2872 (m), 1577
(m), 1464 (vs), 1413 (s), 1375 (m), 1317 (w), 1268 (m), 787 (m),
755 (m), 705 (m), 685 (m). Anal. Calcd for C H N PdS Cl: C
2
3
2
2
(
1
NCH /CH CH CH ), 1.68/1.41 (CH CH CH /CH CH ), 1.41/
.00 (CH CH /CH ). H, C HSQC (400/100 MHz, CD OD): δ
3 2 3 3
2 3 2 2 3 2 2 3 2
1
13
20 25
4
2
1
13
H/δ C 8.05/122.46 (Ar−C), 7.94/132.07, 121.68 (Ar−C, thione),
45.54, H 4.78, N 10.62 found: C 45.63, H 4.69, N 10.53. ESI-MS m/
+
+
7
.71/125.91 (Ar−C), 7.63/122.86 (thione), 4.02/50.00 (NCH ),
z: calcd for [C20
4c: Yield: 0.097 g, 98%. H NMR (400 MHz, DMSO-d
J = 2.4 Hz, 2H, thione), 7.62 (d, J = 2.4 Hz, 2H, thione), 7.34 (s, 3H,
ArH), 6.10−5.98 (m, 2H, CH ),
CH), 5.32−5.20 (m, 4H, NCH
4.77 (d, J = 5.6 Hz, 4H, CH ): δ
CH). C NMR (100 MHz, CDCl
152.09, 138.75, 131.61, 126.23, 121.82, 120.66, 119.19, 119.09, 50.38.
H N PdS ] [M − Cl] 491.0555; found: 491.0568.
25 4 2
1
2
3
.84/50.00 (NCH ), 1.68/31.96 (CH CH CH ), 1.41/20.66
): δ 7.98 (t,
6
2
3
2
2
1
13
(
CH CH ), 1.00/13.99 (CH ). H, C HMBC (400/100 MHz,
3 2 3
1
13
CD OD): δ H/δ C 8.05/125.91 (ArH/Ar−C), 7.94/154.78,
2
2
3
1
3
1
36.70 (thione, ArH/CS, Ar−C), 7.71/125.91, 122.46 (ArH/Ar−
2
3
C, Ar−C), 7.63/154.78, 50.00 (thione/CS, NCH ), 4.02/154.78,
2
−
1
1
2
22.86, 20.66 (NCH /CS, thione, CH CH ), 3.84/154.78, 122.86,
IR (KBr cm ): 3163 (w), 3120 (w), 3077 (w), 2915 (vw), 1638 (w),
1581 (w), 1458 (s), 1407 (s), 1314 (w), 1266 (w), 931 (w), 790 (w),
2
3
2
0.66 (NCH /CS, thione, CH CH ), 1.68/13.99 (CH CH CH /
2
3
2
3
2
2
−
1
CH ). IR (KBr cm ): 3124 (m), 3054 (m), 2958 (m), 2932 (m),
726 (m), 706 (m). Anal. Calcd for C18
H N PdS Cl: C 43.65, H 3.46,
17 4 2
3
2
868 (m), 1611 (m), 1595 (m), 1499 (m), 1432 (s), 1368 (m), 1334
N 11.31 found: C 43.52, H 3.52, N 11.28. ESI-MS m/z: calcd for
+
+
(
w), 883 (m), 762 (m), 686 (m). Anal. Calcd for C H N PdS Cl :
[C18H N PdS ] [M − Cl] 458.9929; found: 458.9930.
17 4 2
4
0
52
8
4
2
C 50.55, H 5.51, N 11.79 found: C 50.46, H 5.60, N 11.83. ESI-MS
General Procedure for the Reduction of Nitro Compounds
with Palladium Complex. Palladium complex (0.001 mmol, 1 mol
+
+
m/z: calcd for [C H N PdS Cl] [M − Cl] 915.1925; found:
40
52
8
4
2
+
2+
%), appropriate nitro compounds (0.1 mmol, 1.0 equiv), and NaBH4
9
4
15.1688; calcd for [C H N PdS ] [M − 2Cl] 439.1117; found:
4
0
52
8
4
(10.0 mmol, 10 equiv) in ethanol (2.0 mL) were charged into a 15
39.1026.
c: Yield: 84.2 mg, 95%. H NMR (400 MHz, CD OD): δ 8.03 (t,
1
mL pressure tube under the air atmosphere. Subsequently, the tube
was sealed and the resulting mixture was stirred at 298 K for 2 h,
filtered through a small pad of silica using EtOAc, and analyzed by
GC−MS chromatography using n-dodecane as an internal standard.
X-ray Structure Determination. Diffraction data of 3a−c, 4a,
and 4c were collected on a Bruker AXS SMART APEX diffractometer,
equipped with a charge-coupled device area detector using Mo Kα
radiation (λ = 0.71073 Å). All data were collected at 298 K, and the
structures were solved by direct methods and subsequently refined on
3
3
J = 2.0 Hz, 2H, ArH), 7.93−7.89 (m, 6H, thione and ArH), 7.75 (dd,
J = 8.0, 2.0 Hz, 4H, ArH), 7.60 (d, J = 2.4 Hz, 4H, thione), 5.78−5.68
(
m, 4H, CH CH), 5.33−5.23 (m, 8H, CH CH), 4.64−4.58 (m,
2
2
1
3
4
H, NCH ), 4.48−4.43 (m, 4H, NCH ). C NMR (100 MHz,
2
2
CD OD): δ 155.10, 136.72, 132.09, 131.37, 126.06, 122.59, 122.55,
3
1
1
1
21.30, 121.03, 52.30. H, H COSY (400/400 MHz, CD OD): δ
3
1
1
H/δ H 7.93/7.60 (thione/thione), 7.93/7.75 (ArH/ArH), 5.78/
1
13
5
.33, 4.64, 4.48 (CH CH/CH CH, NCH , NCH ). H,
C
2
2
2
2
2
60
1
13
F
by using full-matrix least-squares techniques (SHELXL),
HSQC (400/100 MHz, CD OD): δ H/δ C 8.03/122.55 (Ar−C),
7
1
3
61
SADABS absorption corrections were applied to the data, all
nonhydrogen atoms were refined anisotropically, and hydrogen atoms
were located at calculated positions. All calculation was performed
using the Bruker Smart program.
.93/132.09, 121.30 (Ar−C, thione), 7.75/126.06 (Ar−C), 7.60/
22.59 (thione), 5.78/131.37 (CH CH), 5.33/121.03 (CH 
2
2
−
1
CH), 4.64/52.30 (NCH ), 4.48/52.30 (NCH ). IR (KBr cm ): 3150
2
2
(
1
m), 3071 (m), 2983 (w), 2914 (w), 1642 (m), 1596 (m), 1499 (m),
461 (s), 1345 (w), 989 (m), 782 (m), 697 (m), 671 (m). Anal.
ASSOCIATED CONTENT
Supporting Information
Calcd for C H N PdS Cl : C 48.79, H 4.09, N 12.64 found: C
3
6
36
8
4
2
■
+
4
[
[
8.70, H 4.22, N 12.56. ESI-MS m/z: calcd for [C H N PdS Cl]
*
S
3
6
36
8
4
+
2+
M − Cl] 851.0673; found: 851.0468; calcd for [C H N PdS ]
3
6
36
8
4
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.9b00051.
2+
M − 2Cl] 407.0490; found: 407.0401.
General Procedure for the Synthesis of Palladium Com-
pounds 4a−c. PdCl (0.035 g, 0.2 mmol) was added in MeOH (10
2
mL) in a Schlenk tube and kept at room temperature to stirring for 2
h. Then, the mix was put into the corresponding thione ligands (0.2
mmol) and continued to stir for 22 h, the color of the solution
changed from russet to pale yellow. And then, the solvent was
removed with a rotary evaporator, which was dried under vacuum.
NMR data and spectrum of palladium complexes (PDF)
Accession Codes
CCDC 1586431−1586435 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
Single crystals were grown via vapor diffusion of Et O into a saturated
2
solution in CH Cl /MeOH (v/v = 1:1).
2
2
1
4
a: Yield: 0.090 g, 95%. H NMR (400 MHz, DMSO-d ): δ 7.93
6
(
d, J = 2.4 Hz, 2H, thione), 7.66 (d, J = 2.4 Hz, 2H, thione), 7.31 (s,
H, ArH), 4.14 (q, J = 8.0 Hz, 4H, CH CH ), 1.39 (t, J = 7.2 Hz, 6H,
3
3
2
13
CH3). C NMR (100 MHz, DMSO-d ): δ 151.61, 138.75, 131.78,
1
MHz, DMSO-d ): δ H/δ H 7.93/7.66 (thione/thione), 4.14/1.39
6
1
1
AUTHOR INFORMATION
Corresponding Authors
*E-mail: wgjiasy@mail.ahnu.edu.cn (W.-G.J.).
*E-mail: yfhan@nwu.edu.cn (Y.-F.H.).
26.01, 121.60, 120.11, 118.92, 43.62, 14.26. H, H COSY (400/400
■
1
1
6
1
13
1
(
CH CH /CH ). H, C HSQC (400/100 MHz, DMSO-d ): δ H/δ
3
2
3
6
1
3
C 7.93/118.92 (thione), 7.66/120.11 (thione), 7.31/121.60, 126.01
1
13
(
Ar−C, Ar−C), 4.14/43.62 (CH CH ), 1.39/14.26 (CH ). H,
C
3
2
3
ORCID
1
13
HMBC (400/100 MHz, DMSO-d ): δ H/δ C 7.93/151.61, 138.75
6
Wei-Guo Jia: 0000-0001-7976-7543
Ying-Feng Han: 0000-0002-9829-4670
Notes
(
7
thione/CS, Ar−C), 7.66/151.61, 43.62 (thione/CS, CH CH ),
3
2
.31/138.75, 131.78, 121.60, (Ar−H/Ar−C, Ar−C, Ar−C). IR (KBr
−1
cm ): 3149 (m), 3115 (m), 3071 (s), 2972 (m), 2921 (m), 1577
(
(
3
m), 1469 (s), 1450 (vs), 1383 (s), 1313 (m), 1271 (s), 793 (s), 751
The authors declare no competing financial interest.
s), 712 (s), 691 (m). Anal. Calcd for C H N PdS Cl: C 40.77, H
1
6
17
4
2
.64, N 11.89 found: C 40.58, H 3.62, N 11.80. ESI-MS m/z: calcd
ACKNOWLEDGMENTS
We acknowledge the financial support from the National
Nature Science Foundation of China (Nos. 21102004 and
+
+
for [C H N PdS ] [M − Cl] 434.9929; found: 434.9937.
■
16
17
4
2
1
4
b: Yield: 0.101 g, 96%. H NMR (400 MHz, DMSO-d ): δ 7.94
6
(
d, J = 2.4 Hz, 2H, thione), 7.66 (d, J = 2.4 Hz, 2H, thione), 7.30 (s,
G
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX

Organometallics
1722105). W.-G.J. acknowledges the support of the Natural
Science Foundation of Anhui Province (1708085MB44) and
the Natural Science Foundation of the Anhui Higher
Education Institutions of China (KJ2016A845). L.-Y.S. and
Y.-F.H. acknowledge the financial support from the NSFC
Article
2
Suzuki-Miyaura coupling reaction and unprecedented conversion into
nano-sized Pd Se . Chem. Commun. 2010, 46, 5954−5956.
17 15
(
17) Han, Y.-F.; Zhang, L.; Weng, L.-H.; Jin, G.-X. H -Initiated
Reversible Switching between Two-Dimensional Metallacycles and
Three-Dimensional Cylinders. J. Am. Chem. Soc. 2014, 136, 14608−
2
14615.
(
21722105), the National Youth Top-notch Talent Support
(
18) Jia, W.-G.; Huang, Y.-B.; Lin, Y.-J.; Jin, G.-X. Syntheses and
Program of China, the Scientific Research Foundation for the
Returned Overseas Scholars of Shaanxi Province (2017001),
the Shaanxi Key Laboratory of Physical-Inorganic Chemistry
structures of half-sandwich iridium(III) and rhodium(III) complexes
with organochalcogen (S, Se) ligands bearing N-methylimidazole and
their use as catalysts for norbornene polymerization. Dalton Trans.
(
17JS133), and the FM & EM International Joint Laboratory
2
(
008, 5612−5620.
of Northwest University. The authors also thank Dr.
Richmond Lee for English polishing.
19) Jia, W.-G.; Huang, Y.-B.; Jin, G.-X. Synthesis and character-
ization of half-sandwich iridium(III) and rhodium(III) complexes
bearing organochalcogen ligands. J. Organomet. Chem. 2009, 694,
3376−3380.
REFERENCES
■
(
20) Jia, W.-G.; Huang, Y.-B.; Jin, G.-X. Synthesis, characterization
(
1) Owen, G. R. Hydrogen atom storage upon Z-class borane ligand
of novel half-sandwich iridium and rhodium complexes containing
pyridine-based organochalcogen ligands. J. Organomet. Chem. 2009,
694, 4008−4013.
(21) Zhang, L.; Yan, T.; Han, Y.-F.; Hahn, F. E.; Jin, G.-X. Synthesis
of a new type of alkene metal complex using face-capping thione-
alkene ligands. Dalton Trans. 2015, 44, 8797−8800.
(22) Jia, W.-G.; Dai, Y.-C.; Zhang, H.-N.; Lu, X.; Sheng, E.-H.
Synthesis and characterization of gold complexes with pyridine-based
SNS ligands and as homogeneous catalysts for reduction of 4-
nitrophenol. RSC Adv. 2015, 5, 29491−29496.
(23) Jia, W.-G.; Da, Y.-C.; Li, D.-D.; Wang, D.-S.; Sheng, E.-H. Zinc
Complexes Based on Organochalcogen Ligand Mbit: Syntheses,
Structures and Photocatalytic Properties. Chin. J. Struct. Chem. 2015,
34, 1099−1106.
functions: an alternative approach to ligand cooperation. Chem. Soc.
Rev. 2012, 41, 3535−3546.
2) Braunschweig, H.; Dewhurst, R. D.; Schneider, A. Electron-
(
Precise Coordination Modes of Boron-Centered Ligands. Chem. Rev.
010, 110, 3924−3957.
3) Molter, A.; Mohr, F. Gold complexes containing organoselenium
and organotellurium ligands. Coord. Chem. Rev. 2010, 254, 19−45.
4) Ai, P.; Danopoulos, A. A.; Braunstein, P. Transition metal (Rh
2
(
(
and Fe) complexes and main-group (Se and B) adducts with N,N′-
diphosphanyl NHC ligands: a study of stereoelectronic properties.
Dalton Trans. 2016, 45, 4771−4779.
(
5) Sattler, W.; Parkin, G. Reduction of bicarbonate and carbonate
to formate in molecular zinc complexes. Catal. Sci. Technol. 2014, 4,
578−1584.
6) Sattler, W.; Ruccolo, S.; Rostami Chaijan, M.; Nasr Allah, T.;
1
(
(24) Jia, W.-G.; Huang, Y.-B.; Lin, Y.-J.; Wang, G.-L.; Jin, G.-X.
Nickel Complexes and Cobalt Coordination Polymers with Organo-
chalcogen (S, Se) Ligands Bearing an N-Methylimidazole Moiety:
Syntheses, Structures, and Properties. Eur. J. Inorg. Chem. 2008, 2008,
Parkin, G. Hydrosilylation of Aldehydes and Ketones Catalyzed by a
3
Terminal Zinc Hydride Complex, [κ -Tptm]ZnH. Organometallics
2
(
015, 34, 4717−4731.
7) Naga Babu, C.; Srinivas, K.; Prabusankar, G. Facile access to zinc
4
(
063−4073.
25) Lyons, T. W.; Sanford, M. S. Palladium-Catalyzed Ligand-
Directed C−H Functionalization Reactions. Chem. Rev. 2010, 110,
147−1169.
26) He, J.; Wasa, M.; Chan, K. S. L.; Shao, Q.; Yu, J.-Q. Palladium-
Catalyzed Transformations of Alkyl C−H Bonds. Chem. Rev. 2017,
17, 8754−8786.
27) Wei, Y.; Hu, P.; Zhang, M.; Su, W. Metal-Catalyzed
Decarboxylative C−H Functionalization. Chem. Rev. 2017, 117,
864−8907.
28) Park, Y.; Kim, Y.; Chang, S. Transition Metal-Catalyzed C−H
Amination: Scope, Mechanism, and Applications. Chem. Rev. 2017,
17, 9247−9301.
29) Li, M.; Shu, X.; Cai, Z.; Eisen, M. S. Synthesis, Structures, and
and cadmium selones: highly active catalysts for Barbier reactions in
aqueous media. Dalton Trans. 2016, 45, 6456−6465.
(
8) Ghavale, N.; Manjare, S. T.; Singh, H. B.; Butcher, R. J.
1
(
Bis(chalcogenones) as pincer ligands: isolation and Heck activity of
the selone-ligated unsymmetrical C,C,Se-Pd pincer complex. Dalton
Trans. 2015, 44, 11893−11900.
1
(
(
9) Tang, X.-Y.; Li, H.-X.; Chen, J.-X.; Ren, Z.-G.; Lang, J.-P.
Synthetic and structural chemistry of groups 11 and 12 metal
complexes of the zwitterionic ammonium thiolate ligands. Coord.
Chem. Rev. 2008, 252, 2026−2049.
8
(
(
10) Srinivas, K.; Sathyanarayana, A.; Naga Babu, C.; Prabusankar,
G. Bismuth(iii)dichalcogenones as highly active catalysts in multiple
1
(
C-C bond formation reactions. Dalton Trans. 2016, 45, 5196−5209.
(
11) Zhang, M.-J.; Li, H.-X.; Li, H.-Y.; Lang, J.-P. Copper(i) 5-
Norbornene Polymerization Behavior of Neutral Nickel(II) and
Palladium(II) Complexes Bearing Aryloxide Imidazolidin-2-imine
Ligands. Organometallics 2018, 37, 1172−1180.
phenylpyrimidine-2-thiolate complexes showing unique optical
properties and high visible light-directed catalytic performance.
Dalton Trans. 2016, 45, 17759−17769.
(
30) He, R.-T.; Wang, J.-F.; Wang, H.-F.; Ren, Z.-G.; Lang, J.-P.
(
12) Srinivas, K.; Naga Babu, C.; Prabusankar, G. Linear Cu(I)
Palladium dichloride adduct of N,N-bis-(diphenylphosphanylmethyl)-
-aminopyridine: synthesis, structure and catalytic performance in the
decarboxylative cross-coupling of 4-picolinic acid with aryl bromide.
chalcogenones: synthesis and application in borylation of unsym-
2
metrical alkynes. Dalton Trans. 2015, 44, 15636−15644.
(
13) Roy, G.; Jayaram, P. N.; Mugesh, G. Inhibition of
Dalton Trans. 2014, 43, 9786−9794.
(
Lactoperoxidase-Catalyzed Oxidation by Imidazole-Based Thiones
31) Tafesh, A. M.; Weiguny, J. A Review of the Selective Catalytic
Reduction of Aromatic Nitro Compounds into Aromatic Amines,
Isocyanates, Carbamates, and Ureas Using CO. Chem. Rev. 1996, 96,
and Selones: A Mechanistic Study. Chem. Asian J. 2013, 8, 1910−
1
(
921.
14) Zhang, M.-J.; Tan, D.-W.; Li, H.-X.; Young, D. J.; Wang, H.-F.;
2
(
035−2052.
Li, H.-Y.; Lang, J.-P. Switchable Chemoselective Transfer Hydro-
genations of Unsaturated Carbonyls Using Copper(I) N-Donor
Thiolate Clusters. J. Org. Chem. 2018, 83, 1204−1215.
32) Aditya, T.; Pal, A.; Pal, T. Nitroarene reduction: a trusted
model reaction to test nanoparticle catalysts. Chem. Commun. 2015,
51, 9410−9431.
(33) Yang, S.-T.; Shen, P.; Liao, B.-S.; Liu, Y.-H.; Peng, S.-M.; Liu,
S.-T. Catalytic Reduction of Nitroarenes by Dipalladium Complexes:
Synergistic Effect. Organometallics 2017, 36, 3110−3116.
(34) Karami, K.; Mousavi, N. S. A palladium complex immobilized
onto a magnetic GO-MnFe O surface as an effective and recyclable
(
15) Tan, D.-W.; Li, H.-X.; Zhang, M.-J.; Yao, J.-L.; Lang, J.-P.
Acceptorless Dehydrogenation of Alcohols Catalyzed by CuI N-
Heterocycle Thiolate Complexes. ChemCatChem 2017, 9, 1113−
1
(
118.
16) Rao, G. K.; Kumar, A.; Ahmed, J.; Singh, A. K. Palladacycle
containing nitrogen and selenium: highly active pre-catalyst for the
2
4
H
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
catalyst for the reduction of p-nitrophenol. Dalton Trans. 2018, 47,
(51) Ma, L.; Imbesi, P. M.; Updegraff, J. B.; Hunter, A. D.;
Protasiewicz, J. D. Synthesis and Structural Studies of NCN Diimine
Palladium Pincer Complexes Bearing m-Terphenyl Scaffolds. Inorg.
Chem. 2007, 46, 5220−5228.
(52) Feng, J.; Handa, S.; Gallou, F.; Lipshutz, B. H. Safe and
Selective Nitro Group Reductions Catalyzed by Sustainable and
Recyclable Fe/ppm Pd Nanoparticles in Water at Room Temper-
ature. Angew. Chem., Int. Ed. 2016, 55, 8979−8983.
4
(
175−4182.
35) Zhang, W.; Chen, Z.; Al-Naji, M.; Guo, P.; Cwik, S.; Halbherr,
O.; Wang, Y.; Muhler, M.; Wilde, N.; Glaser, R.; Fischer, R. A.
̈
Simultaneous introduction of various palladium active sites into MOF
via one-pot synthesis: Pd@[Cu3−xPd (BTC) ]n. Dalton Trans. 2016,
x
2
4
(
5, 14883−14887.
36) Byun, S.; Song, Y.; Kim, B. M. Heterogenized Bimetallic Pd−
Pt−Fe O Nanoflakes as Extremely Robust, Magnetically Recyclable
(53) Hohloch, S.; Suntrup, L.; Sarkar, B. Arene−Ruthenium(II) and
−Iridium(III) Complexes with “Click”-Based Pyridyl-triazoles, Bis-
triazoles, and Chelating Abnormal Carbenes: Applications in Catalytic
Transfer Hydrogenation of Nitrobenzene. Organometallics 2013, 32,
7376−7385.
3
4
Catalysts for Chemoselective Nitroarene Reduction. ACS Appl. Mater.
Interfaces 2016, 8, 14637−14647.
(
37) Letort, S.; Lejeune, M.; Kardos, N.; Metay, E.; Popowycz, F.;
́
Lemaire, M.; Draye, M. New insights into the catalytic reduction of
aliphatic nitro compounds with hypophosphites under ultrasonic
irradiation. Green Chem. 2017, 19, 4583−4590.
(54) Wienhofer, G.; Sorribes, I.; Boddien, A.; Westerhaus, F.; Junge,
̈
K.; Junge, H.; Llusar, R.; Beller, M. General and Selective Iron-
Catalyzed Transfer Hydrogenation of Nitroarenes without Base. J.
Am. Chem. Soc. 2011, 133, 12875−12879.
(
38) Yuan, G.; Jiang, H.; Zhang, L.; Liu, Y.; Cui, Y. Metallosalen-
based crystalline porous materials: Synthesis and property. Coord.
Chem. Rev. 2019, 378, 483−499.
(55) Ganta, S.; Chand, D. K. Nanoscale metallogel via self-assembly
of self-assembled trinuclear coordination rings: multi-stimuli-respon-
sive soft materials. Dalton Trans. 2015, 44, 15181−15188.
(
39) Guo, Y.; Li, J.; Zhao, F.; Lan, G.; Li, L.; Liu, Y.; Si, Y.; Jiang, Y.;
Yang, B.; Yang, R. Palladium-modified functionalized cyclodextrin as
an efficient and recyclable catalyst for reduction of nitroarenes. RSC
Adv. 2016, 6, 7950−7954.
(56) Yuan, G.; Shan, W.; Chen, J.; Tian, Y.; Wang, H. Synthesis,
structure and photophysical properties of a binuclear Zn(II) complex
based on 8-hydroxyquinoline ligand with naphthyl unit. J. Lumin.
(
40) Diachenko, V.; Page, M. J.; Gatus, M. R. D.; Bhadbhade, M.;
2
(
015, 160, 16−21.
Messerle, B. A. Bimetallic N-Heterocyclic Carbene Rh(I) Complexes:
Probing the Cooperative Effect for the Catalyzed Hydroelementation
of Alkynes. Organometallics 2015, 34, 4543−4552.
57) Shan, W.; Shan, X.; Li, X.; Liu, J.; Zhang, L.; Yuan, G. Self-
assembly and luminescent properties of one novel tetranuclear Cd(II)
complex based on 8-hydroxyquinolinate ligand. Inorg. Chem. Commun.
2014, 48, 131−135.
(
41) Collado, A.; Bohnenberger, J.; Oliva-Madrid, M.-J.; Nun, P.;
I
Cordes, D. B.; Slawin, A. M. Z.; Nolan, S. P. Synthesis of Au - and
Au -Bis(NHC) Complexes: Ligand Influence on Oxidative Addition
to Au Species. Eur. J. Inorg. Chem. 2016, 2016, 4111−4122.
(
III
(58) Li, H.; Shang, J.; Ai, Z.; Zhang, L. Efficient Visible Light
Nitrogen Fixation with BiOBr Nanosheets of Oxygen Vacancies on
the Exposed {001} Facets. J. Am. Chem. Soc. 2015, 137, 6393−6399.
I
42) Tyson, G. E.; Tokmic, K.; Oian, C. S.; Rabinovich, D.; Valle, H.
(59) Helgert, T. R.; Hollis, T. K.; Valente, E. J. Synthesis of
U.; Hollis, T. K.; Kelly, J. T.; Cuellar, K. A.; McNamara, L. E.;
Hammer, N. I.; Webster, C. E.; Oliver, A. G.; Zhang, M. Synthesis,
characterization, photophysical properties, and catalytic activity of an
SCS bis(N-heterocyclic thione) (SCS-NHT) Pd pincer complex.
Dalton Trans. 2015, 44, 14475−14482.
Titanium CCC-NHC Pincer Complexes and Catalytic Hydro-
amination of Unactivated Alkenes. Organometallics 2012, 31, 3002−
3009.
(
60) Sheldrick, G. SHELXL-97, a Program for Refining Crystal
Structures; University of Gottingen: Germany, 1997.
61) Sheldrick, G. SADABS, Bruker/Siemens Area Detector Absorption
̈
(
43) Slivarichova, M.; Reading, E.; Haddow, M. F.; Othman, H.;
(
Owen, G. R. Silver and Palladium Complexes Containing Ditopic N-
Heterocyclic Carbene-Thione Ligands. Organometallics 2012, 31,
Correction Program, version 2.01; Bruker AXS: Madison, WI, 1998.
6
(
595−6607.
44) Zhang, L.-M.; Li, H.-Y.; Li, H.-X.; Young, D. J.; Wang, Y.; Lang,
J.-P. Palladium(II) Chloride Complexes of N,N′-Disubstituted
Imidazole-2-thiones: Syntheses, Structures, and Catalytic Perform-
ances in Suzuki−Miyaura and Sonogashira Coupling Reactions. Inorg.
Chem. 2017, 56, 11230−11243.
(
45) Wang, Y.-T.; Gao, B.-B.; Wang, F.; Liu, S.-Y.; Yu, H.; Zhang,
W.-H.; Lang, J.-P. Palladium(ii) and palladium(ii)−silver(i) com-
plexes with N-heterocyclic carbene and zwitterionic thiolate mixed
ligands: synthesis, structural characterization and catalytic properties.
Dalton Trans. 2017, 46, 1832−1839.
(
46) Grundemann, S.; Albrecht, M.; Loch, J. A.; Faller, J. W.;
̈
Crabtree, R. H. Tridentate Carbene CCC and CNC Pincer
Palladium(II) Complexes: Structure, Fluxionality, and Catalytic
Activity. Organometallics 2001, 20, 5485−5488.
(
47) Frutos-Pedreno, R.; García-Sanchez, E.; Oliva-Madrid, M. J.;
̃
́
Bautista, D.; Martínez-Viviente, E.; Saura-Llamas, I.; Vicente, J. C−H
Activation in Primary 3-Phenylpropylamines: Synthesis of Seven-
Membered Palladacycles through Orthometalation. Stoichiometric
Preparation of Benzazepinones and Catalytic Synthesis of Ureas.
Inorg. Chem. 2016, 55, 5520−5533.
(
48) Ma, L.; Woloszynek, R. A.; Chen, W.; Ren, T.; Protasiewicz, J.
D. A New Twist on Pincer Ligands and Complexes. Organometallics
006, 25, 3301−3304.
49) Azerraf, C.; Gelman, D. New Shapes of PC(sp )P Pincer
Complexes. Organometallics 2009, 28, 6578−6584.
50) Lipke, M. C.; Woloszynek, R. A.; Ma, L.; Protasiewicz, J. D. m-
2
(
3
(
Terphenyl Anchored Palladium Diphosphinite PCP-Pincer Com-
plexes That Promote the Suzuki−Miyaura Reaction Under Mild
Conditions. Organometallics 2009, 28, 188−196.
I
DOI: 10.1021/acs.organomet.9b00051
Organometallics XXXX, XXX, XXX−XXX