Phosphane-ligated ionic palladium complexes: Synthesis, characterization and application as efficient and reusable precatalysts for the homogeneous carbonylative sonogashira reaction under CuI-free conditions

Article abstract of DOI:10.1002/ejic.201301318

The stable ionic Pd^II complexes 1A-4A were synthesized through the complexation of PdCl₂(MeCN)₂ with the phosphane-functionalized ionic liquids (FILs) 1-4 with π-acceptor character. Single-crystal X-ray diffraction analyses showed that 1A-4A were all composed of Pd^II-centred square-planar cations and triflate (OTf^-, CF₃SO₃^-) counteranions. The complex cations in 1A-3A possessed structural similarity to trans-PdCl₂(PPh₃)₂. The cation in 4A was a new Pd^II-centered planar complex ligated by the phosphane-carbon anion-carbene (PCC) pincer in a tripodal manner. The stabilities of 1A-4A were improved due to the intensive π-backbonding interaction between the Pd and P atoms. When complexes 1A-4A were used as precatalysts for homogeneous carbonylative Sonogashira coupling of PhI with phenylacetylene free of CuI, 1A-3A exhibited excellent catalytic behaviour with a TON of up to 1700 at a CO pressure of 0.5 MPa and moderate temperature of 100 °C, whereas 4A exhibited poor activity towards the transformation of PhI due to the high stability of 4A. The recycling experiments of 3A in [Bpy]BF₄ (as a solvent) indicated that 3A could be recycled for 5 runs with neither activity loss nor metal leaching into the organic phase. Complex 3A also proved to be a general precatalyst for the carbonylative Sonogashira couplings of a wide range of aryl iodides with phenylacetylene. The selectivity of the desired carbonylation product depended more on electronic effects than the steric effects of the substituents of the aryl iodides.

Full text of DOI:10.1002/ejic.201301318

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DOI:10.1002/ejic.201301318
Phosphane-Ligated Ionic Palladium Complexes: Synthesis,
Characterization and Application as Efficient and
Reusable Precatalysts for the Homogeneous Carbonylative
Sonogashira Reaction under CuI-Free Conditions
Jing Zhang,[a] Yongyong Wang,[a] Xiaoli Zhao,[a] and Ye Liu*[a]
Keywords: Palladium complexes / Phosphanes / Carbonylation / Carbonylative Sonogashira reaction / Ionic liquids /
Functionalized ionic liquids
The stable ionic PdII complexes 1A–4A were synthesized
through the complexation of PdCl2(MeCN)2 with the phos-
phane-functionalized ionic liquids (FILs) 1–4 with π-acceptor
character. Single-crystal X-ray diffraction analyses showed
that 1A–4A were all composed of PdII-centred square-planar
free of CuI, 1A–3A exhibited excellent catalytic behaviour
with a TON of up to 1700 at a CO pressure of 0.5 MPa and
moderate temperature of 100 °C, whereas 4A exhibited poor
activity towards the transformation of PhI due to the high
stability of 4A. The recycling experiments of 3A in [Bpy]BF4
cations and triflate (OTf–, CF3SO3–) counteranions. The com- (as a solvent) indicated that 3A could be recycled for 5 runs
plex cations in 1A–3A possessed structural similarity to trans-
PdCl2(PPh3)2. The cation in 4A was a new PdII-centered
planar complex ligated by the phosphane–carbon anion–
carbene (PCC) pincer in a tripodal manner. The stabilities of
1A–4A were improved due to the intensive π-backbonding
interaction between the Pd and P atoms. When complexes
1A–4A were used as precatalysts for homogeneous carb-
onylative Sonogashira coupling of PhI with phenylacetylene
with neither activity loss nor metal leaching into the organic
phase. Complex 3A also proved to be a general precatalyst
for the carbonylative Sonogashira couplings of a wide range
of aryl iodides with phenylacetylene. The selectivity of the
desired carbonylation product depended more on electronic
effects than the steric effects of the substituents of the aryl
iodides.
chlorides in the presence of transition metal reagents.[9] Un-
fortunately, this methodology is limited with respect to
functional-group tolerance, substrate stability, reaction con-
ditions (dry solvent under an inert gas), low atom economy
and environmental unfriendliness.[10] Since first being re-
ported in 1981 by Tanaka,[11] palladium-catalyzed carb-
onylative Sonogashira reactions of aryl halides have become
an alternative for the synthesis of α,β-alkynones. Most re-
cently, remarkable improvements have been reported by Wu
and Beller for homogeneous carbonylative Sonogashira re-
actions,[1,12] and Xia[10] and others[13] for heterogeneous
ones. Much effort has been focused on the development of
Pd–phosphane complexes for the synthesis of α,β-alkyn-
ones by means of carbonylative Sonogashira reactions un-
der homogeneous conditions,[1,14] which suffers from diffi-
cult product separation, rapid activity loss and nonrecycl-
ability.
From environmental and economic points of view, the
development of more efficient, recoverable and recyclable
but moisture- and air-insensitive Pd complex catalysts,
which allow the manipulation of the carbonylative Sonoga-
shira reaction with low catalyst loadings under copper-free
conditions and without the need of exclusion of air and
moisture, is highly demanded. Involatile ionic liquids (ILs)
have been recognized as promising alternative solvents,
Introduction
Carbonylation represents an industrial core technology
for transforming bulk and fine chemicals to a diverse set of
useful products[1–3] in which CO acts as a most important
C1 building block for introducing the carbonyl group into
the parent molecule. However, carbonylations are compara-
tively little used in more complicated organic syntheses.[1]
Encouragingly, in the last decades, palladium-catalyzed
carbonylation of aryl halides in the presence of nucleophiles
has attracted much attention and become a promising tool
for the synthesis of aromatic carbonyl compounds such as
esters, acids, amides and ketones due to increasing aware-
ness of the need for an environmentally benign and efficient
methodology in organic synthesis.[1,4–8] Among the aro-
matic carbonyl compounds, α,β-alkynones are crucial struc-
tural motifs in many bioactive molecules and important key
intermediates for the synthesis of natural products and
pharmaceuticals.[7,8] In general, α,β-alkynones are prepared
by the coupling of alkyne organometallic reagents with acyl
[a] Shanghai Key Laboratory of Green Chemistry and Chemical
Processes, Chemistry Department of East China Normal
University,
Shanghai 200062, P. R. China
E-mail: yliu@chem.ecnu.edu.cn
http://faculty.ecnu.edu.cn/s/754/main.jspy
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which can immobilize homogeneous palladium catalysts nating ability for immobilizing the transition-metal cata-
and then prevent their leaching and deactivation.[15] On the lysts into the ILs in their catalytic reactions.[17] As a part of
other hand, ILs can be flexibly functionalized by varying our continued activities in the functionalization of ILs for
the cations and/or anions that constitute IL structure with homogeneous catalysis,[18] a series of ionic PdII complexes
specific functional moieties. Thus, it is possible to develop 1A–4A ligated by the phosphane-FILs 1–4 was synthesized,
abundant functionalized ILs (FILs) possessing the dual and the compounds were investigated comparatively as pre-
characteristics of the incorporated functionalities as well as catalysts for carbonylative Sonogashira reactions under
that of the IL. Canac and Chauvin had carried out a lot CuI-free conditions (Scheme 1). The monophosphane- and
of valuable research work on this kind of phosphane-FILs biphosphane-FILs with different electronic and steric ef-
ligand,[16] and Andrieu has developed new convenient fects were explored in order to regulate the structural con-
methods for the preparation of the phosphenium analogues, figurations and then tailor the catalytic performance of the
which showed strong π-acceptor character and great coordi- corresponding ionic Pd complexes. For the first time, the
Scheme 1. Syntheses of the ionic Pd complexes 1A–4A ligated by the phosphane-FILs 1–4.
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biphosphane-FIL 4[19a] was found to act as a potential trip- moisture-stable both in the solid state and in organic sol-
odal ligand of the phosphane–carbon anion–carbene (PCC) vents for several weeks under ambient conditions. Their
pincer type with strong π-acceptor character. This afforded molecular structures elucidated by single-crystal X-ray dif-
a PCC-chelated Pd complex (4A). In addition, due to the fraction are depicted in Figure 1, and each is composed of
compatibility of 1A–4A with the room-temperature IL the PdII complex cation and OTf– counteranions. Unexcep-
(RTIL) N-butylpyridinium tetrafluoroborate ([Bpy]BF4), tionally, the structures of the complex cations in 1A, 2A
the latter, without any coordinating ability, was selected as and 3A are similar to that in trans-PdCl2(PPh3)2,[20] which
the solvent to guarantee homogeneous catalysis. As ex- itself exhibits a square-planar geometry. The PdII (d8) cen-
pected, with the RTIL [Bpy]BF4 as the solvent, the ionic ter, situated at the center of inversion, is coordinated by
phosphane-ligated complexes 1A–4A, which combined the two chloride ions and two imidazolium-based phosphane
Pd complex and the IL in one unit with the advantages over ligands in trans positions. As for 3A, due to long and flexi-
each individual, could catalyze carbonylative Sonogashira ble arms of the bis(imidazolio)butyl-linked biphosphane,
reactions efficiently, with the additional merits of recycl- the chelated biphosphanes and two chloride ions are both
ability and facile manipulation.
conveniently located in a trans-chelating manner, as in the
mono-phosphane in 1A, 2A or trans-PdCl2(PPh3)2. The to-
tal potential solvent-accessible volume of 1A after removal
of the solvent molecules is 11.7%, as calculated by using
the PLATON/VOID routine.[21] Surprisingly, the ionic Pd
complex 4A chelated by the phosphane–carbon cation–
Results and Discussion
Synthesis and Characterization
The complexation of PdCl2(CH3CN)2 with the phos- carbene (PCC) pincer was obtained as the major product
phane-FILs 1–4 led to the formation of the ionic complexes in a yield of 55% along with some unidentified by-products
of 1A–4A, respectively, in different configurations, accord- when PdCl2(MeCN)2 was complexed with ligand 4 in the
ing to similar preparation procedures we have reported be- absence of any additive. Obviously, in ligand 4, the hetero-
fore.[18f] The ionic PdII complexes 1A–4A were all air- and lytic cleavage of one N2C–P bond to give a transient N-
Figure 1. Single-crystal structures of 1A–4A (H atoms are omitted for clarity).
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Table 1. Comparison of selected bond lengths, bond angles, and 31P NMR signals for the various Pd complexes.
Pd complex
Bond length
[Å]
Bond angle
[°]
31P NMR signal
δ [ppm]
1A
2A
3A
4A
Pd1–P
Pd1–Cl
Pd1–P
Pd1–Cl
Pd1–P
Pd1–Cl
Pd1–P
Pd1–Cl
Pd1–C
Pd1–P
Pd1–Cl
2.3355 (13), 2.3336 (14)
2.2704 (16), 2.2991 (14)
2.3296 (6)
P1–Pd1–P2
Cl1–Pd1–Cl2
P1–Pd1–P2
Cl1–Pd1–Cl2
P1–Pd1–P2
Cl1–Pd1–Cl2
P1–Pd1–C22
Cl1–Pd1–C17
Cl1–Pd1–P1
P1–Pd1–P2
Cl1–Pd1–Cl2
179.4
178.8
180.0
180.0
176.5
178.2
171.4
170.6
88.9
16.0 ([D6]acetone)
19.7 ([D6]acetone)
12.7 ([D6]acetone)
9.6 (CD3CN)
2.2900 (6)
2.3263 (11), 2.3380 (11)
2.2643 (13), 2.3017 (11)
2.2504 (6)
2.3771 (6)
2.010 (2), 2.028 (3)
2.3721 (10)
[20]
trans-PdCl2(PPh3)2
180.0
180.0
24.0 ([D6]DMSO)
2.3111(13)
heterocyclic carbene (NHC) and the deprotonation at the shifts for 1A (δ = 16.0 ppm), 2A (δ = 19.7 ppm), 3A (δ =
C-2 position of meta-phenylene to afford a carbon anion 12.7 ppm) and 4A (δ = 9.6 ppm) were observed, which fur-
could induce the formation of the stable compound 4A, ther substantiates the increased electron density of the
which was the first example to trap the potential PCC tripo- phosphorus atoms in 1A–4A due to the π-acceptor charac-
dal pincer in a Pd complex. A similar heterolytic cleavage of ter of the corresponding phosphanes and the intensive π-
the N2C–P bond to give a transient N-heterocyclic carbene back donation of d-electrons from the Pd ion to the phos-
(NHC), along with cleaved diphenyphosphenium as an ad- phorus fragment.
duct to the metal center, has been observed by Canac and
Chauvin when their developed cationic imidazoliophos-
phane was complexed with Pd0(allyl)(MeCN)2 with the aid
Catalytic Performance of the Ionic Pd Complexes 1A–4A
for the Carbonylative Sonogashira Reaction
of the nucleophile [Et4N]+Cl–.[19b] However, attempts to
trap the phosphane–carbon anion–phosphane (PCP) pincer
through the deprotonation at the C-2 position of meta-
The carbonylative coupling of phenylacetylene with
phenylene 4 into an RhCl(CO) fragment was unsuccessful iodobenzene was selected as a model reaction under CuI-
in their work.[19a] In our case, the formation of the thermo- free conditions (Table 2). DMF and [Bpy]BF4 were selected
dynamically most stable 4A with the fused five- and six- as the optimal solvents to afford acceptable conversions of
membered rings chelated to the Pd center, with indication PhI, with excellent selectivity, to 1,3-diphenylprop-2-yn-1-
of much shorter bonds for Pd–P (2.2504 Å) and Pd–C one under mild conditions (1.5 h, 90 °C) (Entries 2 and 4).
(2.010, 2.028 Å), was the key driving force for the in situ Reasonably, 0.5 MPa of CO was selected as the optimal
induction of the PCC pincer from 4 without the aid of any pressure condition to provide 94% conversion of PhI with
nucleophile.
99% carbonylative coupling selectivity (Entry 2 vs. 1 and
Table 1 summarizes the comparative data of selected 3). Under atmospheric pressure of CO (balloon), only 60%
bond lengths, bond angles and 31P NMR signals of 1A–4A. of PhI was converted with 74% selectivity to the carb-
In contrast, the Pd–P distances of 1A–4A (2.25–2.33 Å) onylated product, indicating that the pressure of CO kinet-
were universally shorter than that in the neutral analogue ically corresponded to the reaction rate and the selectivity
trans-PdCl2(PPh3)2 (2.37 Å), indicating the enhanced inter- to the carbonylative Sonogashira coupling against the Son-
action between the Pd–P linkages. In comparison with PPh3 ogashira coupling. Under the applied conditions (0.5 MPa
as a typical electron-rich donor with strong σ-donating abil- CO, 90 °C), in [Bpy]BF4, a relatively low reaction rate was
ity, the phosphane-FILs 1–4 are relatively weak σ-electron observed with 0.5 mol.-% of 1A with a TON of 153. This
donors but strong π-electron acceptors, due to the intense could be increased to 1711 at 100 °C while reducing the
electron-withdrawing effect on the P atom from the vicinal concentration of 1A ten-fold to 0.05 mol.-% (Entry 4 vs. 5),
positively charged imidazolium ring. Consequently, the Pd– indicating the marked influence of temperature on the reac-
P linkages in 1A–4A were strengthened, and the stabilities tion rate of the selective carbonylative Sonogashira cou-
of them against oxidative degradation were improved re- pling. In comparison to [Bpy]BF4, [Bmim]BF4 as the sol-
markably due to the π-back donation of d-electrons from vent resulted in a low iodobenzene conversion of 77% (En-
the Pd ion to the phosphorus fragment. Besides the π-back try 5 vs. 7), probably due to the unfavorable ligation of
donation from the Pd to the P atom in 4A, the tripodal [Bmim]BF4 as an NHC ligand to the PdII center, which acts
chelating mode of the PCC pincer further consolidates the against the selective carbonylative coupling.
Pd–P linkage leading to the shortest Pd–P bond length
(2.2504 Å).
Under optimal conditions in [Bpy]BF4 (Pd-catalyst con-
centration 0.05 mol.-%, 0.5 MPa CO, 100 °C, 1.5 h), the
The 31P NMR signals of 1A–4A in Table 1 show that, in catalytic performance of 1A–4A for the carbonylative Sono-
comparison with the 31P NMR signal of trans-PdCl2- gashira coupling of phenylacetylene with iodobenzene was
(PPh3)2 (δ = 24.0 ppm),[20] relatively high-field chemical investigated in parallel (see Table 3). It was found that, un-
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Table 2. Optimization of the reaction conditions for carbonylative Sonogashira coupling of iodobenzene with phenylacetylene catalyzed
by 1A.[a]
Entry
Solvent
Concentration of 1A
Temperature
[°C]
CO
[MPa]
Conversion of PhI
[%][d]
Selectivity[d,e]
[%]
TON
[mol-%]
1
2
DMF
DMF
DMF
0.5
0.5
0.5
90
90
90
1.0
0.5
balloon
0.5
0.5
0.5
99
94
60
82
93
83
77
99
99
74
93
92
93
91
196
186
89
3
4[b]
5
[BPy]BF4
[BPy]BF4
[BPy]BF4
[Bmim]BF4
0.5
90
153
0.05
0.025
0.05
100
100
100
1711
1544
1400
6
7[c]
0.5
[a] PhI (5 mmol), phenylacetylene (6 mmol), Et3N (7.5 mmol), solvent (3 mL), reaction time 1.5 h. [b] [Bpy]BF4 = N-butylpyridinium
tetrafluoroborate. [c] [Bmim]BF4 = 1-butyl-3-metylimidazolium tetrafluoroborate. [d] GC and GC-MS analysis. [e] Besides 1,3-di-
phenylprop-2-yn-1-one as the desired carbonylated product, 1,2-diphenylethyne was found as the only by-product coming from the
Sonogashira coupling.
der the same conditions, the ionic PdII complexes 1A–3A
Beller[12a] and Mori[22] have proposed reaction mecha-
with a square-planar configuration similar to that of trans- nisms for the competitive carbonylative Sonogashira cou-
PdCl2(PPh3)3 all exhibited excellent activity towards the pling/Sonogashira coupling reactions in the presence of Pd
conversion of PhI with selectivity to the alkynone at a high catalysts under CO. It was claimed that, for both of these
TON of up to ca. 1700 (Entries 1–3), without obvious dis- coupling reactions, the oxidative addition of an aryl halide
crimination from the steric and electronic effects by the co- (ArX) to the active Pd0–L species was the first step in the
ordinated phosphane. In contrast, 4A, chelated by the PCC catalytic circle. The Pd0–L species could be generated, in
pincer, exhibited very poor activity in the same reaction general, through the reduction of PdII complexes by Et3N,
(Entry 4, 7% conversion of PhI). When the conventional an extra ligand and/or an alkyne.[23,24] However, the impact
trans-PdCl2(PPh3)3 was applied as the precatalyst instead, of CO on the reduction of PdII to Pd0 could not be ignored
competitive activity and selectivity to the alkynone were ob- either.[25] To the best of our knowledge, CO as a strong
served. As shown in Table 1, the Pd–P bonds in 1A–3A were ligand, which possesses both σ-donor and π-acceptor char-
slightly shorter than that in trans-PdCl2(PPh3)3, indicating acteristics, can coordinate to the Pd0 complexes preferen-
an improved stability of 1A–3A. As a result, the dissoci- tially and rapidly. Hence, we believe that the oxidative ad-
ation of the phosphane ligand to form the active Pd0–L (L dition of ArX to the active Pd0–L species is followed, fore-
= phosphane ligand) species and the subsequent insertion most, by the coordination of CO to Pd0–L as illustrated in
of the substrate might be depressed to some extent in the Scheme 2. The initial coordination of CO to the active Pd0–
course of catalysis (Scheme 2). Encouragingly, the results in L species gives the corresponding active CO-ligated Pd0–L
Table 3 show that the improved stability of 1A–3A did not species I. Subsequent oxidative addition of ArX to the CO-
compromise their activity dramatically, and this is a good ligated Pd0–L species I affords the intermediate arylpalladi-
sign for the precatalyst durability.
um(II) complex II. Afterwards, the acylpalladium complex
Table 3. The catalytic performance of different Pd complexes for carbonylative Sonogashira coupling of aryl halide with phenylacetylene
in [Bpy]BF4.[a]
Entry
Catalyst
Conversion of PhI[b]
[%]
Yield [%][b,c]
1,3-diphenylprop-2-yn-1-one
TON
1,2-diphenylethyne
1
2
3
4
5
1A
93
92
93
7
92
91
92
56
93
8
9
8
44
7
1711
1674
1711
78
2A
3A
4A
trans-Pd(PPh3)2Cl2
93
1730
[a] Pd concentration 0.05 mol-%, PhI (5.0 mmol), phenylacetylene (6.0 mmol), Et3N (7.5 mmol), [Bpy]BF4 (3 mL), CO (0.5 MPa), tem-
perature 100 °C, time 1.5 h. [b] GC analysis. [c] Besides 1,3-diphenylprop-2-yn-1-one as the desired carbonylated product, 1,2-diphenyl-
ethyne was found as the only by-product coming from the Sonogashira coupling.
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Scheme 2. Proposed mechanism for the carbonylative Sonogashira coupling/Sonogashira coupling reactions in the presence of Pd catalysts.
III is formed after CO migration and insertion by means of investigated by using 3A in [Bpy]BF4 for the carbonylative
electrophilic attack. With the aid of a base, the halide (X) Sonogashira of phenylacetylene with iodobenzene. Upon
in III was exchanged by phenyl acetylide to yield the trans- completion of each run, the reaction slurry was washed
metallated species V, and the desired alkynone is formed with diethyl ether to extract the reactants and products
by subsequent reductive elimination. As we have mentioned from the IL phase. The residue was reused without ad-
above, the 31P NMR signals for 1A–3A indicated an in- ditional treatment. As shown in Figure 2, compound 3A
creased electron density of the phosphorus atoms due to could be recycled for at least five runs without activity loss
the intensive π-back donation of d-electrons from the Pd or selectivity decrease. On the other hand, after the five-run
ion to the cationic phosphorus fragment. On the basis of recycling, the total loss of 3A in terms of the Pd amount in
the catalytic mechanism of the carbonylative Sonogashira the combined organic phases was below the ICP detection
reaction proposed in Scheme 2, the electron-rich character limit (Ͻ 0.1 μgg–1 on the basis of ICP analysis) revealing
in the P-ligated Pd0-species (Pd0–L) gives rise to oxidative that 3A was tightly locked in the [Bpy]BF4 medium without
addition of the aryl halide leading to the rapid carb- any leaching into the organic phase due to the ionic com-
onylative transformation. It means that, as for 1A–3A, al- patibility.
though the dissociation of the phosphane ligand (L) to
form the active Pd0–L species is depressed to some extent,
the subsequent oxidative addition of the aryl halide (I Ǟ
II) is accelerated due to the electron-rich character in the
P-ligated Pd0 species. This is the rate-determining step for
the overall carbonylative coupling. Hence, excellent cata-
lytic performances of 1A–3A with the additional merit of
good stability were observed in this work.
However, the most stable compound, 4A, ligated by the
PCC pincer in a tripodal manner completely inhibited the
dissociation of the phosphane ligand to form the active Pd0
species and then impeded the accommodation of the sub-
strates (CO and/or PhI), leading to the poor transformation
of PhI to the alkynone.
The purpose of incorporating the palladium complex
into the IL structure was to combine the characteristics of
the palladium complex and the IL, which was expected to
provide the recyclability of the IL as well as the catalytic
ability of the traditional neutral Pd complexes. To demon-
Figure 2. Recycling of 3A in [Bpy]BF4 for carbonylative Sonoga-
shira coupling of iodobenzene with phenylacetylene [3A (0.05 mol-
%), PhI (5.0 mmol), phenylacetylene (6.0 mmol), Et3N (7.5 mmol),
strate this issue, recovery and recycling experiments were [Bpy]BF4 (3 mL), CO (0.5 MPa), temperature 100 °C, time 1.5 h].
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The generality of 3A as the precatalyst for the carb- nation for the steric properties of the substituents (En-
onylative Sonogashira coupling was examined for different tries 1–6). However, when activated aryl iodides with elec-
aryl halides (Table 4). Since the competing reactions of tron-withdrawing substituents such as –CF3 or –NO2 were
Sonogashira cross-couplings and Glaser homo-couplings of used to couple with phenylacetylene, markedly decreased
phenylacetylene occurred unavoidably,[12a] the correspond- selectivity to the carbonylative coupling products was
ing side-products of aryl-substituted internal acetylenes and found, although complete conversion of PhI occurred (En-
1,4-diphenylbutadiyne were found universally.
tries 7–12). Particularly, in the cases of para-, meta- and
When aryl iodides were used to couple with phenylacetyl- ortho-iodonitrobenzene, the Sonogashira coupling was ab-
ene in 3A-[Bpy]BF4 under CO pressure, the electronic prop- solutely the predominant reaction over the carbonylative
erties of the substituents showed obvious influences on the one under the applied conditions (Entries 10–12). As illus-
selectivity of the coupling products. The aryl iodides with trated in Scheme 2, although the activated aryl iodides
electron-donating substituents, such as methyl and meth- could undergo more rapid oxidative addition to CO-ligated
oxy, reacted with phenylacetylene to generate the corre- Pd0–L active species I to generate the intermediate arylpal-
sponding carbonylative coupling products in excellent ladium complex II, the subsequent intermolecular electro-
yields with trace amounts of the side-products coming from philic attack of CO to the arylpalladium species could be
the Sonogashira coupling and without obvious discrimi- depressed if the nucleophilicity of the aryl group in II was
Table 4. Generality of 3A as the precatalyst for the carbonylative Sonogashira coupling of aryl halides with phenylacetylene in
[Bpy]BF4.[a]
[a] 3A (0.05 mol.-%), aryl halide (5 mmol), phenylacetylene (6 mmol), Et3N (7.5 mmol), CO (0.5 MPa), [Bpy]BF4 (3 mL), temperature
[c]
100 °C, time 2 h. [b] GC and GC-MS analysis. The side-product of 1,4-diphenylbutadiyne coming from Glaser homo-coupling, besides
[d]
[e]
the internal acetylenes coming from Sonogashira coupling, was observed in some cases.
3A (0.5 mol-%), N2 (1.0 MPa) instead of CO, time 6 h.
3A (0.5 mol-%), CO (1.0 MPa), time 6 h.
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weakened because of the presence of an electron-with- compounds 1A–3A exhibited excellent catalytic behavior
drawing group such as –CF3 or –NO2, leading to the Sono- with a TON up to 1700, values which are competitive with
gashira reaction almost exclusively. In comparison with that of trans-PdCl2(PPh3)2 and with the additional merit of
CF3-substituted iodobenzenes solely with the electron-with- insensitivity to moisture and oxygen. However, 4A, with the
drawing inductive effect, NO2-substituted iodobenzenes best stability, exhibited poor activity towards the transfor-
were featured with not only the electron-withdrawing induc- mation of PhI. The recyclability of the precatalyst was in-
tive effect but also an intensive conjugated effect. This was vestigated for 3A, and this could be recycled for 5 runs in
attributed to the more electron-deficient character. Hence, [Bpy]BF4 without obvious activity loss nor detectable metal
the Sonogashira reaction of the intermediate arylpalladi- leaching. Compound 3A also proved to be a general precat-
um(II) complex II with a terminal alkyne would be a prefer- alyst for the carbonylative Sonogashira coupling of a wide
able pathway to the sluggish electrophilic attack of CO on range of aryl iodides with phenylacetylene. In the proposed
the electron-deficient aryl group for the formation of acyl- catalytic mechanism for carbonylative Sonogashira cou-
palladium species III. Consequently, the Sonogashira cou- pling/Sonogashira coupling reactions in the presence of Pd
pling absolutely predominated over the carbonylative Sono- catalysts, it was believed that the oxidative addition of the
gashira coupling, especially when an NO2 substituent was active Pd0–L species to ArX was followed by the foremost
located ortho or para in the iodobenzene. Similarly, the acti- coordination of CO, and the resultant CO-ligated Pd0–L
vated substrate of 2-iodothiophene or 2-iodopyridine with species I exhibited relatively lower activity for oxidative ad-
an electron-withdrawing effect due to the presence of the S- dition of PhX than the naked Pd0–L species.
or N-atom with high electronegativity also gave rise to the
Sonogashira coupling (Entries 13 and 14). In particular, for
2-iodopyridine, no carbonylative coupling was observed at
Experimental Section
all due to the inefficient electrophilic attack of CO on the
General Considerations: The chemical reagents were purchased
electron-deficient pyridylpalladium complex II (Entry 14).
from Shanghai Aladdin Chemical Reagent Co. Ltd. and Alfa Aesar
The transformation of PhBr, with relatively low reactivity,
China, and used as received. THF was dried with sodium/benzo-
phenone and distilled freshly before use. CH2Cl2 was heated to re-
was inefficient, even though harsher conditions were ap-
plied [Entry 15: cat. (0.5 mol.-%), CO (1.0 MPa), 6 h].
flux with calcium hydride and distilled freshly before use. FTIR
However, when the reaction was conducted under N2
(1.0 MPa) instead of CO, the coupling of PhBr with phenyl-
spectra were recorded with a Nicolet NEXUS 670 spectrometer.
1H and 31P NMR spectra (85% H3PO4 was used as external stan-
acetylene led to 1,2-diphenylethyne in a yield of 68% (En- dard) were recorded with a Bruker Avance 500 spectrometer at
298 K. The amount of Pd in the organic phase was quantified by
using an inductively coupled plasma atomic emission spectrometer
(ICP-AES) in connection with an IRIS Intrepid II XSP instrument
(Thermo Electron Corporation). CHN elemental analysis was per-
formed with a Vario EL III Element Analyzer. Gas chromatog-
raphy (GC) was performed with a SHIMADZU-2014 instrument
equipped with a DM-Wax capillary column (30 mϫ0.25 mmϫ
0.25 μm). GC-mass spectrometry (GC-MS) data was recorded with
an Agilent 6890 instrument equipped with an Agilent 5973 mass-
selective detector.
try 16), indicating that the oxidative addition of PhBr to the
Pd0–L species under N2 proceeded much faster than that to
the CO-ligated Pd0–L species I under CO. This supports
our conjecture that the oxidative addition of ArX to the
active Pd0–L species was followed, foremost, by the coordi-
nation of CO (Scheme 2). The CO-ligated Pd0–L active spe-
cies I exhibited lower activity towards the oxidative ad-
dition of the inactive ArBr in comparison with the naked
Pd0–L species.
Synthesis
1-Butyl-2-diphenylphosphino-3-methylimidazolium Triflate (1): To a
solution of 1-butylimidazole (6.6 g, 53.0 mmol) in dry CH2Cl2
(50 mL) cooled to –78 °C was added nBuLi (2.2 m, in hexane,
27 mL, 59.4 mmol) dropwise under N2. After stirring of the mix-
ture for 1 h, chlorodiphenylphosphane (13.1 g, 59.4 mmol) was
added dropwise. The suspension was stirred for another 1 h and
then warmed to ambient temperature. At room temperature, the
mixture was stirred continuously for another 2 h. After quenching
Conclusions
The ionic PdII complexes 1A–4A, ligated by the phos-
phane-FILs 1–4 (or their derivatives) with π-acceptor char-
acter, were synthesized for the first time and fully charac-
terized. Single-crystal X-ray diffraction analyses show that
compounds 1A–4A are all composed of PdII-centered
–
square-planar cations and OTf– (CF3SO3 ) counteranions. excess nBuLi with deionized water, the oily mixture obtained after
removal of the solvent in vacuo was repeatedly washed with diethyl
ether and then purified by silica gel column chromatography with
an eluent of petroleum ether/ethyl acetate (PE/EA, 1:3) to afford
1-butyl-2-diphenylphosphinoimidazole as a white solid (13 g, yield
80 wt.-%). The obtained solids (7.0 g, 23 mmol) were then dissolved
in dry CH2Cl2 (30 mL), and the solution was cooled under N2 to
–78 °C, whereupon methyl triflate (3.8 g, 23 mmol) was added. The
reaction mixture was stirred vigorously at –78 °C for 1 h and then
warmed to ambient temperature. After removal of the solvent un-
The complex cations in 1A–3A possess structural similarity
with trans-PdCl2(PPh3)2. The cation in 4A is a new PdII-
centered planar complex moiety ligated by the PCC pincer
in a tripodal manner and is derived from the phosphane-
FIL 4. The Pd–P bonds in 1A–4A, which are universally
shorter than that in trans-PdCl2(PPh3)2, indicate improved
stability due to the intensive π-backbonding interaction be-
tween the Pd and P atoms. When compounds 1A–4A were
used as precatalysts for homogeneous carbonylative Sono-
der vacuum, the obtained residue was recrystallized from EA/
1
gashira coupling of PhI with phenylacetylene free of CuI, EtOEt to yield 1 as a white solid (9.7 g; yield 90 wt.-%). H NMR
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([D6]acetone): δ = 7.91 (s, 1 H, NCHCHN+), 7.81 (s, 1 H,
NCHCHN+), 7.52 (m, 6 H, HAr), 7.32 (m, 4 H, HAr), 4.31 (t, J = H, NCHCHNCH2), 4.06–4.01 (t, J = 8 Hz, 4 H, NCH2CH2), 1.79–
δ = 7.63 (s, 2 H, NCHN), 7.10 (s, 2 H, NCHCHNCH2), 6.96 (s, 2
8 Hz, 2 H, NCH2CH2CH2CH3), 3.54 (s, 3 H, N+CH3), 1.59 (m, 2
H, CH2CH2CH2CH3), 1.19 (m, 2 H, CH2CH2CH2CH3), 0.81 (t, J
= 6 Hz, 3 H, CH2CH2CH2CH3) ppm. 31P NMR (CDCl3): δ =
–28.18 (s, PPh2) ppm.
1.72 (m, 4 H, NCH2CH2) ppm.
To a solution of 1,4-bis(imidazol-1-yl) butane (1.15 g, 6 mmol) in
dry THF (50 mL) cooled to –78 °C was added nBuLi (1.6 m in hex-
ane, 4.5 mL, 7.2 mmol) dropwise under N2. After stirring of the
mixture for 1 h, chlorodiphenylphosphane (1.59 g, 7.2 mmol) was
added dropwise. The suspension was stirred at –78 °C for another
1 h and then warmed to ambient temperature. After removal of the
solvent under vacuum, the residue was purified by silica gel column
chromatography with an eluent of PE/EA = 3:1, affording 1,4-
bis(2Ј-diphenylphosphinoimidazol-1Ј-yl)butane as a white solid
(1.88 g, yield 56 wt.-%). To a solution of this 1,4-bis(2Ј-diphenyl-
phosphinoimidazol-1Ј-yl)butane (2.0 g, 3.6 mmol) in dry CH2Cl2
(40 mL) cooled to –78 °C under N2 was added methyl triflate
(0.63 g, 3.8 mmol). The solution was stirred with the reaction tem-
perature increasing from –78 °C to ambient, after which it was then
stirred continuously at room temperature for another 2 h. After
removal of the solvent under vacuum, the residue was washed with
Et2O (3ϫ 10 mL) and recrystallized from CH2Cl2/Et2O to afford
1-Butyl-2-diphenylphosphino-3-methylbenzo[d]imidazolium Triflate
(2): To a three-necked flask were added 1H-benzo[d]imidazole
(11.8 g, 0.1 mol), n-iodobutane (27.6 g, 0.15 mol), NaOH (20 g,
0.5 mol) and TBAB (tetrabutylammonium bromide; 0.8 g,
2.5 mmol) sequentially. The resultant mixture was stirred at 70 °C
for 24 h, and a layer separation of two phases was observed. The
separated organic layer was washed with water (3ϫ 25 mL) and
then dried with anhydrous MgSO4. After filtration and solvent re-
moval in a rotary evaporator, the collected residue was purified by
silica gel column chromatography with an eluent of PE/EA = 1:3 to
1
afford 1-butylbenzo[d]imidazole (14.4 g, yield 83 wt.-%). H NMR
([D6]acetone): δ = 8.13 (s, 1 H, NCHN), 7.70 (d, J = 8 Hz, 1 H,
HAr), 7.57 (d, J = 8 Hz, 1 H, HAr), 7.29–7.20 (m, 2 H, 5, HAr),
4.83–4.29 (t, J = 7.5 Hz, 2 H, NCH2CH2CH2CH3), 1.91–1.83 (m,
2 H, CH2CH2CH2CH3), 1.39–1.29 (m, 2 H, CH2CH2CH2CH3),
0.95–0.91 (t, J = 8 Hz, 3 H, CH2CH2CH2CH3) ppm.
1
3 as white crystals (3.03 g, yield 95 wt.-%). H NMR ([D6]acetone,
298 K): δ = 8.00–7.99 (t, J = 2 Hz, 1 H, N+CHCHN), 7.93 (d, 1
H, N+CHCHN), 7.58–7.54 (m, 6 H, HAr), 7.49–7.46 (m, 4 H, HAr),
4.37–4.36 (m, 2 H, NCH2CH2), 3.67 (s, 3 H, N+CH3), 1.56–1.54
(m, 2 H, NCH2CH2) ppm. 31P ([D6]acetone): δ = – 27.6 (s, PPh2)
ppm.
To a solution of 1-butylbenzo[d]imidazole (8.6 g, 49.4 mmol) in dry
THF (50 mL) cooled to –78 °C was added nBuLi (1.6 m in hexane,
37.0 mL, 59.3 mmol) dropwise under N2. After stirring of the mix-
ture for 1 h, chlorodiphenylphosphane (13.0 g, 59.3 mmol) was
added dropwise. The resultant mixture was stirred at –78 °C for
another 1 h and then warmed up to ambient temperature. After
quenching excess nBuLi with deionized water, the solvent was re-
moved from the oily mixture in vacuo. The obtained residue was
purified by silica gel column chromatography with an eluent of PE/
EA = 8:1 to give 1-butyl-2-(diphenylphosphanyl)benzo[d]imidazole
1,3-Bis(2Ј-diphenylphosphino-3Ј-methylimidazolio)benzene Triflate
(4): To distilled DMSO (100 mL) were added imidazole (6.8 g,
100 mmol), K2CO3 (20 g, 145 mmol), N,N-dimethylglycine (1.85 g,
18 mmol), CuI (1.7 g, 9 mmol) and 1,3-dibromobenzene (10.6 g,
45 mmol) in sequence under N2, and the obtained mixture was
stirred vigorously at 130 °C for 24 h. After cooling to room tem-
perature, the mixture was diluted with water and then extracted
with CH2Cl2. The combined organic phases were dried with anhy-
drous MgSO4. The residue after removal of the organic solvent in
vacuo was then purified by silica gel column chromatography with
the eluent of CH2Cl2/CH3OH = 10:1 to give 1,3-bis(1-imidazolyl)-
1
as a white solid (10.27 g, yield 58 wt.-%). H NMR ([D6]acetone):
δ = 7.62 (d, J = 8 Hz, 1 H, HAr), 7.59–7.53 (m, 5 H, HAr), 7.39–
7.36 (m, 6 H, HAr), 7.27–7.18 (m, 2 H, HAr), 4.45–4.41 (t, J =
7.5 Hz,
2
H, NCH2CH2CH2CH3), 1.66–1.60 (m,
2
H,
CH2CH2CH2CH3), 1.28–1.23 (m, 2 H, CH2CH2CH2CH3), 0.81–
0.78 (t, J = 7.5 Hz, 3 H, CH2CH2CH2CH3) ppm.
1
benzene as a white powder (5.1 g, yield 54 wt.-%). H NMR ([D6]-
acetone): δ = 8.24 (s, 2 H, NCHN), 7.95–7.94 (t, J = 2 Hz, 1 H,
NCCHCN), 7.75–7.74 (t, J = 1.5 Hz, 2 H, NCHCHNPh), 7.71–
7.63 (m, 3 H, NCCHCHCHCN), 7.15 (s, 2 H, NCHCHNPh) ppm.
To a solution of 1-butyl-2-(diphenylphosphanyl)benzo[d]imidazole
(1.29 g, 3.6 mmol) in dry CH2Cl2 (40 mL) cooled to –78 °C under
N2 was added methyl triflate (0.62 g, 3.8 mmol). The solution was
stirred with the reaction temperature increasing from –78 °C to am-
bient after which it was stirred continuously at room temperature
for another 2 h. After removal of the solvent under vacuum, the
residue was washed with diethyl ether (3ϫ 10 mL) to afford 2 as a
The ionic biphosphane 1,3-bis(2Ј-diphenylphosphino-3Ј-methyl-
imidazolio)benzene triflate (4) was prepared afterwards according
to a published method.[19a]
Bis[1-butyl-2-diphenylphosphino-3-methylimidazolio]dichloridopalla-
dium(II) Triflate (1A): 1A, bis[1-butyl-2-diphenylphosphino-3-
methylimidazolio]dichloropalladium(II) triflate, as a trans-dichlo-
ropalladium triflate complex of ligand 1 was prepared aaccording
to our previously published method.[18f] Yellow crystals of 1A were
obtained from acetone/diethyl ether at room temperature (yield
92 wt.-%). 1H NMR ([D6]acetone): δ = 8.34–8.30 (m, 4 H, HAr),
8.10 (s, 1 H, NCHCHN+), 8.05 (s, 1 H, NCHCHN+), 7.90–7.88
(m, 2 H, HAr), 7.81–7.78 (m, 4 H, HAr), 4.02–3.99 (t, J = 7.5 Hz,
2 H, NCH2CH2CH2CH3), 3.86 (s, 3 H, N+CH3), 1.63–1.60 (m, 2
H, CH2CH2CH2CH3), 1.13–1.10 (m, 2 H, CH2CH2CH2CH3),
0.76–0.73 (t, J = 7.5 Hz, 3 H, CH2CH2CH2CH3) ppm. 31P ([D6]-
acetone): δ = 16.0 (s, PPh2) ppm. C42H48Cl2F6N4O6P2PdS2
(1122.20): calcd. C 44.95, H 4.31, N 4.99; found C 44.96, H 4.42,
N 4.06.
1
white powder (1.84 g, yield 98 wt.-%). H NMR ([D6]acetone): δ =
8.17–8.14 (m, 1 H, HAr), 8.07–8.05 (m, 1 H, HAr), 7.82–7.77 (m, 2
H, HAr), 7.71–7.58 (m, 10 H, HAr), 4.81–4.76 (t, 2 H, J = 8 Hz,
NCH2CH2CH2CH3), 3.94 (s, 3 H, N+CH3), 1.69–1.62 (m, 2 H,
CH2CH2CH2CH3), 1.30–1.28 (m, 2 H, CH2CH2CH2CH3), 0.81–
0.77 (t, 3 H, J = 7.5 Hz, CH2CH2CH2CH3) ppm. 31P NMR ([D6]-
acetone): δ = 20.4 (s, PPh2) ppm.
1,4-Bis(2Ј-diphenylphosphino-3Ј-methylimidazolio)butane
Triflate
(3): To a solution of NaOH (10 g, 0.25 mol) in water (80 mL) were
added imidazole (15 g, 0.22 mol) and TBAB (1.5 g, 4.65 mmol). Af-
ter heating to reflux for 2 h, the mixture was treated with 1,4-di-
bromobutane (21.59 g, 0.1 mol) at room temperature, and this re-
sulted in the immediate precipitation of white solids. The obtained
mixture was stirred vigorously for another 5 h to complete the reac-
tion. The resultant residue after filtration was washed with acetone
and then dried under vacuum to yield a white powder of 1,4-bis-
Bis[1-butyl-2-diphenylphosphino-3-methylbenzo[d]imidazolio]di-
chloridopalladium(II) Triflate (2A): A mixture of PdCl2(CH3CN)2
(imidazol-1-yl)butane (14.1 g, yield 74 wt.-%). 1H NMR (CD3OD): (233.5 mg, 0.9 mmol) and ligand 2 (459.7 mg, 1.8 mmol) was dis-
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solved in CH2Cl2 (20 mL) and stirred vigorously at 40 °C for 8 h.
After evaporation of the solvent, the crude residue was recrys-
tallized from CH2Cl2/Et2O at room temperature to give 2A as
orange crystals (yield 89 wt.-%). 1H NMR ([D6]acetone): δ = 8.48–
8.44 (m, 4 H, HAr), 8.15–8.10 (m, 2 H, HAr), 7.97–7.94 (t, J =
7.5 Hz, 2 H, HAr) 7.86–7.81 (m, 6 H, HAr), 4.34–4.31 (t, J = 8.5 Hz,
2 H, NCH2CH2CH2CH3), 4.19 (s, 3 H, N+CH3), 1.59–1.53 (m, 2
H, CH2CH2CH2CH3), 1.09–1.04 (m, 2 H, CH2CH2CH2CH3),
0.80–0.77 (t, J = 7.5 Hz, 3 H, CH2CH2CH2CH3) ppm. 31P ([D6]-
acetone): δ = 19.7 (s, PPh2) ppm. C50H52Cl2F6N4O6P2PdS2
(1222.34): calcd. C 49.13, H 4.29, N 4.58; found C 48.67, H 4.33,
N 4.49.
(713.37): calcd. C 45.46, H 3.25, N 7.85; found C 45.15, H 3.43, N
7.76.
X-ray Crystallography: Intensity data were collected at 173 K for
1A–4A with a Bruker SMARTAPEX II diffractometer by using
graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å). Data
reduction included absorption corrections carried out by using the
multi-scan method. The structures were solved by direct methods
and refined by full-matrix least squares using SHELXS-97,[26] with
all non-hydrogen atoms refined anisotropically. Hydrogen atoms
were added at their geometrically ideal positions and refined iso-
tropically. The crystal data and refinement details are given in
Table 5. CCDC-952853 (for 1A), -952854 (for 2A), -952855 (for
3A), and -952856 (for 4A) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[1,4-Bis(2Ј-diphenylphosphino-3Ј-methylimidazolio)butane]dichlor-
idopalladium(II) Triflate (3A): A mixture of PdCl2(CH3CN)2
(50 mg, 0.193 mmol) and ligand 3 (170.9 mg, 0.193 mmol) was dis-
solved in CH2Cl2 (2 mL) and stirred vigorously at room tempera-
ture for 3 h. After removal of the solvent, the crude residue was
recrystallized from CH2Cl2/Et2O at room temperature to give 3A
as yellow crystals (yield 91 wt.-%). 1H NMR (CD3COCD3): δ =
8.37 (s, 2 H, N+CHCHN), 8.06–8.01 (m, 8 H, HAr), 7.87–7.72 (m,
12 H, HAr), 7.58 (s, 2 H, N+CHCHN) 5.07 (s, 4 H, NCH2CH2),
3.42 (s, 6 H, N+CH3), 2.37 (s, 4 H, NCH2CH2) ppm. 31P ([D6]-
General Procedures for the Carbonylative Sonogashira Reaction Cat-
alyzed by 1A–4A: In a typical experiment, the isolated crystalline
precatalyst 1A (0.0025 mmol) was mixed with [Bpy]BF4 (2 mL)
iodobenzene (5 mmol), phenylacetylene (6 mmol) and Et3N
(7.5 mmol) sequentially. The resultant homogeneous mixture was
stirred vigorously at 100 °C for 1.5 h. Upon completion, the reac-
tion mixture was cooled to room temperature and then extracted
with diethyl ether (3ϫ 3 mL). The diethyl ether fractions were com-
bined and then analyzed by GC to determine the conversions (1-
dodecane as internal standard) and the selectivities (normalization
method). The structures of the obtained products were further con-
firmed by GC-MS. The remaining slurry containing the Pd cata-
lyst, [Bpy]BF4 and the formed ammonium salt (Et3N·HI) was then
used directly without further treatment for the next run if not speci-
δ = 8.28–8.27 (t, J = 2 Hz, 1 H, fied. In the specified cases, an additional 1 mL of [Bpy]BF4 was
acetone):
δ = 12.7 (s, PPh2) ppm. C38H38Cl2F6N4O6P2PdS2
(1064.10): calcd. C 42.89, H 3.60, N 5.27; found C 41.25, H 3.80,
N 5.11.
Monochloridopalladium(II) Triflate Complex of Ligand 4 (4A): A
mixture of PdCl2(MeCN)2 (50 mg, 0.193 mmol) and ligand 4
(174.7 mg, 0.193 mmol) was dissolved in dry CH2Cl2 (2 mL) and
stirred vigorously at room temperature for 3 h. After removal of
the solvent, the crude residue was recrystallized from CH3CN/Et2O
at room temperature to give 4A as white crystals (yield 55 wt.-%).
1H NMR (CD3CN):
NCCHCHCHCN), 7.80–7.75 (m, 5 H, HAr, N+CHCHN), 7.72– added to dissolve the ammonium salt (Et3N·HI) and ensure normal
7.69 (m, J = 2 Hz, 3 H, NCCHCHCHCN, N+CHCHN), 7.62–7.60 stirring. Afterwards, the retaining IL phase was collected for the
(m, 4 H, HAr), 7.48–7.41 (m, 3 H, HAr, NCHCHN), 7.19 (t, J = next run. Due to the stoichiometric consumption of the base, Et3N
2 Hz, 1 H, NCHCHN), 4.19 (s, 3 H, N+CH3), 3.23 (s, 3 H, NCH3)
(7.5 mmol) was added additionally per pass. All manipulations
ppm. 31P (CD3CN): δ = 9.6 (s, PPh2) ppm. C27H23ClF3N4O3PPdS were conducted in air.
Table 5. Crystal data and structure refinement for1A–4A.
1A
2A
3A
4A
Empirical formula
Formula mass
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C42H48Cl2F6N4O6P2PdS2 C50H52Cl2F6N4O6P2PdS2 C38H38Cl2F6N4O6P2PdS2 C27H23ClF3N4O3PPdS
1122.20
triclinic
P1
1222.32
monoclinic
P21/n
1064.08
triclinic
P1
713.37
orthorhombic
Pbca
¯
¯
13.8485(9)
14.1790(9)
15.7065(10)
99.622(2)
112.324(2)
105.689(2)
2617.5(3)
2
14.1602(4)
8.9394(3)
21.6062(7)
90
93.5660(10)
90
2729.70(15)
2
1.487
14.7293(7)
17.5313(8)
21.6153(11)
90.449(2)
101.4090(10)
99.701(2)
5388.2(4)
4
9.1936(3)
19.2091(7)
31.6711(12)
90
90
90
5593.1(3)
8
1.694
α [°]
β [°]
γ [°]
V [Å3]
Z
dcalcd. [Mgm–3]
μ (Mo-Kα) [mm–1]
T [K]
1.424
1.312
0.664
173(2)
0.71073
30233
0.644
296(2)
0.71073
30585
0.642
173(2)
0.71073
62546
0.949
173(2)
0.71073
61359
λ [Å]
Total reflections
Unique reflections (Rint
R1 [IϾ 2σ(I)]
wR2 (all data)
F(000)
)
9122 (0.0333)
0.0618
0.2027
4789 (0.0359)
0.0294
0.0789
18891 (0.0415)
0.0564
0.1662
4918 (0.0339)
0.0252
0.0629
2864
1144
1248
2152
Goodness-of-fit on F2
1.039
1.038
1.077
1.062
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H. Neumann, M. Beller, Angew. Chem. 2011, 123, 11338; An-
gew. Chem. Int. Ed. 2011, 50, 11142–11146.
Acknowledgments
[13] a) T. Fukuyama, R. Yamaura, I. Ryu, Can. J. Chem. 2005, 83,
711–715; b) M. T. Rahman, T. Fukuyama, N. Kamata, M.
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Sha, S. Sheng, M. Cai, J. Mol. Catal. A 2009, 298, 94–98.
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ence Foundation of China (Nos. 21273077 and 21076083), the 973
Program from the Ministry of Science and Technology of China
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Received: October 10, 2013
Published Online: January 21, 2014
Eur. J. Inorg. Chem. 2014, 975–985
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