Samarium(II) Monoalkyl Complex Supported by a β-Diketiminato-Based Tetradentate Ligand: Synthesis, Structure, and Catalytic Hydrosilylation of Internal Alkynes

Article abstract of DOI:10.1002/chem.202000342

The synthesis and catalytic applications of trivalent rare-earth metal alkyl complexes have been well developed, but the chemistry of divalent rare-earth metal alkyl complexes lagged much behind. Herein, we report the synthesis, structure, and catalytic applications of a samarium(II) monoalkyl complex supported by a β-diketiminato-based tetradentate ligand, [LSmCH(SiMe₃)₂] (L=[MeC(NDipp)CHC(Me)NCH₂CH₂N(Me)CH₂CH₂NMe₂]^?, Dipp=2,6-(iPr)₂C₆H₃). This complex is synthesized by the salt metathesis reaction of samarium iodide [LSm(μ-I)]₂ and KCH(SiMe₃)₂ in 63 % yield. Its structure is characterized by single-crystal X-ray diffraction, showing a distorted square-pyramid coordination geometry. This samarium(II) monoalkyl complex exhibits high catalytic activity in the hydrosilylation of aryl and methyl-substituted unsymmetrical internal alkynes with secondary hydrosilanes, selectively providing the α-(E) products in high yields.

Full text of DOI:10.1002/chem.202000342

A Journal of
Accepted Article
Title: Samarium(II) Monoalkyl Complex Supported by a β-diketiminato
Based Tetradentate Ligand: Synthesis, Structure and Catalytic
Hydosilylation of Internal Alkynes
Authors: Xiaojuan Liu, Qingqing Wen, Li Xiang, Xuebing Leng, and
Yaofeng Chen
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Chem. Eur. J. 10.1002/chem.202000342
Link to VoR: http://dx.doi.org/10.1002/chem.202000342
Supported by

10.1002/chem.202000342
Chemistry - A European Journal
FULL PAPER
Samarium(II) Monoalkyl Complex Supported by a β-diketiminato
Based Tetradentate Ligand: Synthesis, Structure and Catalytic
Hydrosilylation of Internal Alkynes
Xiaojuan Liu,[a] Qingqing Wen,[a] Li Xiang,*[a,b] Xuebing Leng,[a] and Yaofeng Chen*[a]
[a]
[b]
X. Liu, Q. Wen, Prof. Dr. L. Xiang, Dr. X. Leng, Prof. Dr. Y. Chen
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry
University of Chinese Academy of Sciences, Chinese Academy of Sciences
345 Lingling Road, Shanghai 200032, P. R. China
E-mail: yaofchen@mail.sioc.ac.cn
Prof. Dr. L. Xiang
Chongqing Key Laboratory of Green Synthesis and Applications
College of Chemistry, Chongqing Normal University
Chongqing 401331, P. R. China
E-mail: xiangli@cqnu.edu.cn
Supporting information for this article is given via a link at the end of the document.
Abstract: The synthesis and catalytic applications of trivalent rare-
earth metal alkyl complexes have been well developed, but the
chemistry of divalent rare-earth metal alkyl complexes much lagged
behind. Here we report the synthesis, structure and catalytic
application of a samarium(II) monoalkyl complex supported by a β-
more importance, as their reactivity can be efficiently tuned by an
anionic supporting ligand. The first example of such complexes,
[(C5Me5)Sm{CH(SiMe3)2}(C5Me5)K(THF)2]n, was reported by Hou
and coworkers in 2001.[3g,h] This complex can be viewed as a
neutral samarium(II) alkyl species “[(C5Me5)Sm{CH(SiMe3)2}]”
stabilized by [(C5Me5)K]. Later, Takats and coworkers used a
bulky pyrazolylborate ligand TptBu,Me to stabilize samarium(II)
monoalkyl complex [(TptBu,Me)SmCH(SiMe3)2].[3i] Overall, to the
diketiminato based tetradentate ligand, [LSmCH(SiMe3)2] (L
=
[MeC(NDipp)CHC(Me)NCH2CH2N(Me)CH2CH2NMe2]−, Dipp = 2,6-
(iPr)2C6H3). This complex is synthesized via the salt metathesis
reaction of samarium iodide [LSm(µ-I)]2 and KCH(SiMe3)2 in 63% yield. best of our knowledge, there are only three samarium(II)
Its structure is characterized by the single-crystal X-ray diffraction,
showing a distorted square pyramid coordination geometry. This
samarium(II) monoalkyl complex exhibits high catalytic activity in
hydrosilylation of aryl and methyl-substituted unsymmetrical internal
alkynes with secondary hydrosilanes, selectively providing the α-(E)
products in high yields.
monoalkyl complexes have been reported up to date,[3g-i] and their
catalytic applications are little explored.[3g,h] It should be noted that
for the stabilization of Sm(II)–C bond Trifonov and coworkers
recently designed and synthesized several samarium(II) benzyl
derivatives[4], and they also used the complexes as the catalysts
for the intermolecular hydrophosphination of olefins.[4b]
Vinylsilanes have been widely used as important building
blocks in organic synthesis.[5] Hydrosilylation of alkynes, the
addition of a Si−H bond across C−C triple bond, represents the
most straightforward method and the most atom-economical
reaction for the synthesis of vinylsilanes.[6] In contrast to terminal
alkynes or symmetrical internal alkynes hydrosilylation,
hydrosilylation of unsymmetrical internal alkynes has met with
limited success due to the increased difficulty in regiocontrol.
Some late transition metals,[7] manganese[8] and titanium
catalysts[9] have been reported for this reaction recently.
Hydrosilylation of unsymmetrical internal alkynes catalysed by
rare-earth metal complexes were little explored, and no
successful example of rare-earth metal catalysed stereo- and
regio-selective hydrosilylation of aryl and alkyl-substituted
unsymmetrical internal alkynes with secondary hydrosilanes has
been reported.[10] We have developed a -diketiminato based
Introduction
Rare-earth metal alkyl complexes have been of great research
interests in the past three decades, such type of complexes
exhibit rich reactivity and applications in both stoichiometric and
catalytic reactions.[1] However, the research was dominated by
trivalent rare-earth metal alkyl complexes, the related derivatives
of divalent rare-earth metal complexes remain scare and much
less explored, owing to their reducibility, strong tendency to
undergo ligand redistribution, and β-hydrogen elimination or β-
hydrogen abstraction.[2,3] It is also worth noting that the synthesis
of samarium(II) alkyl complexes is even more challenging than
that of ytterbium(II) and europium(II) complexes, due to
samarium(II) ion's stronger reducibility and larger size. Until 1997,
Izod and coworkers reported the first crystallographically
tetradentate
ligand
(L)
(L
=
[MeC(NDipp)CHC(Me)NCH2CH2N(Me)CH2CH2NMe2]− , Dipp =
2,6-(iPr)2C6H3), which can stabilize a series of highly reactive rare-
characterized
samarium(II)
alkyl
complex
[Sm{C(SiMe3)2(SiMe2OMe)}2(THF)], which contains two bulky
alkyl ligands.[3a] The samarium(II) monoalkyl complexes are of
earth metal complexes.[11] Recently, we synthesized
a
ytterbium(II) monoalkyl complex based on the ligand L, and found
1
This article is protected by copyright. All rights reserved.

10.1002/chem.202000342
Chemistry - A European Journal
FULL PAPER
that the complex can efficiently catalyse the homo- and cross-
coupling of primary arylsilanes.[12] Interestingly, this ligand can
also stabilize the synthetically challenging samarium(II)
monoalkyl complex. Herein, we report the synthesis and structure
of this samarium monoalkyl complex and its catalytic application
for the hydrosilylation of aryl and methyl-substituted
unsymmetrical internal alkynes with secondary hydrosilanes.
After the divalent samarium iodide 1 was obtained, the
synthesis of the corresponding samarium alkyl complex was
carried out. Reaction of 1 with KCH2SiMe3 did not give the divalent
samarium alkyl complex, which is possibly due to its low stability.
On the other hand, complex 1 reacts with KCH(SiMe3)2 in THF to
afford a divalent samarium alkyl complex [LSmCH(SiMe3)2] (2) as
a deep red solid in 63% yield (Scheme 1), the bulky alkyl group is
benefit for the stabilization of the complex. Complex 2 was
characterized by 1H NMR spectroscopy, elemental analysis, and
single-crystal X-ray crystallography (Figure 2). The samarium(II)
ion in 2 has a distorted square pyramid coordination geometry,
with four nitrogen atoms of L forming the basal plane and a carbon
atom of the alkyl ligand occupying the apical position. The Sm–C
Results and Discussion
Reaction of SmI2(THF)2 with a potassium salt of ligand KL (L =
[MeC(NDipp)CHC(Me)NCH2CH2N(Me)CH2CH2NMe2]−, Dipp
=
2,6-(iPr)2C6H3) in THF at room temperature provided a divalent
samarium iodide [LSm(µ-I)]2 (1) as a green solid in 62% yield
(Scheme 1). The complex was characterized by 1H NMR
spectroscopy and elemental analysis, and its structure was
further confirmed by single-crystal X-ray crystallography. The
molecular structure of 1, shown in Figure 1, is similar to that of
[LYb(µ-I)]2.[12] In the complex, each samarium(II) ion is
coordinated by four nitrogen atoms of the ligand (L) and two
bridging iodides, displaying a distorted octahedral geometry.
Although N3 and N4 atoms of L both act as the neutral donors,
the distance from N4 atom to samarium ion is significantly longer,
2.786(5) Å vs 2.683(4) Å. The two Sm−I bond lengths are not
equal, one is 3.324(1) Å while the other is 3.286(1) Å. The shorter
Sm−I bond length is comparable with those in [(tBu4Carb)Sm(µ-
I)(THF)2]2 (3.2665(4) and 3.2853(4) Å).[4a]
bond length is 2.707(5) Å, which is slightly longer than that of
[3g]
2.652(9) Å in [(C5Me5)Sm{CH(SiMe3)2}(C5Me5)K(THF)2]n
and
2.667(5) Å in (TptBu,Me)SmCH(SiMe3)2.[3i] Similar to that observed
in 1, the Sm−N4 bond length (2.806(4) Å) is longer than the
Sm−N3 bond length (2.693(3) Å).
Figure 1. Molecular structure of complex 2 with ellipsoids at 30% probability
level. Dipp isopropyl groups and hydrogen atoms were omitted for clarity.
Selected bond distances [Å] and angles [°]: Sm‒N1 2.508(3), Sm‒N2 2.512(4),
Sm‒N3 2.693(3), Sm‒N4 2.806(4), Sm‒C25 2.707(5).
Scheme 1. Synthesis of samarium(II) diketiminato iodide complex 1 and alkyl
complex 2.
Both divalent ytterbium alkyl complex [LYbCH2SiMe3] and
divalent samarium alkyl complex 2 were tested for catalytic
hydrosilylation of phenylmethylacetylene with phenylsilane.
Unsurprisingly, when [LYbCH2SiMe3] was used as catalyst,
redistribution of phenylsilane was dominated and no
hydrosilylation product was detected. [LYbCH2SiMe3] has been
reported to be a highly efficient catalyst for the redistribution of
primary arylsilanes.[12] However, by using 2 mol% of 2, 24% yield
of vinylsilanes were observed at 30 oC within 1.5 hours (Table 1,
entry 1). The reaction is highly stereo- and regio-selective, only
syn-addition products are produced and the ratio of α-(E) product
(A) to β-(E) product (B) is 11:1. The domination of the α-(E)
product reveals that the electronic effects play the major role in
regio-control, as the phenyl group stabilizes partial negative
charge on the benzylic carbon of the reaction intermediate when
it is located  to metal ion, this reaction intermediate is formed
from an addition of Sm–H bond of the catalytic species to the C–
C triple bond of the phenylmethylacetylene. If the steric effects
play the major role, the reaction produces the β-(E) product, which
minimizes the repulsion between the phenyl and silyl groups.
When the reaction time was prolonged to 3 hours, the yield of
vinylsilanes slightly increased to 31%, indicating a quick decay of
Figure 1. Molecular structure of complex 1 with ellipsoids at 30% probability
level. Dipp isopropyl groups and hydrogen atoms were omitted for clarity.
Selected bond distances [Å] and angles [°]: Sm–N1 2.521(4), Sm‒N2 2.564(4),
Sm‒N3 2.683(4), Sm‒N4 2.786(5), Sm‒I 3.324(1), Sm‒I(A) 3.286(1), Sm-I-
Sm(A) 94.31(2), I-Sm-I(A) 85.69(2).
2
This article is protected by copyright. All rights reserved.

10.1002/chem.202000342
Chemistry - A European Journal
FULL PAPER
the catalytic activity. Recently, Cui, Li and their coworkers
reported the dihydrosilylation of internal alkynes catalysed by a
lanthanum bis(amido) ate complex.[13] For the hydrosilylation of
phenylmethylacetylene with phenylsilane catalysed by 2, no
dihydrosilylation product was observed. Then, we examined the
substituent moves to the meta-position, the yield and selectivity
are up to 98% and >97%, respectively. Introducing a methyl group
to the ortho-position of phenylmethylacetylene causes a decrease
of the product yield to 72%, but the selectivity for the α-(E) product
is excellent (>97%). The p-OMe, NMe2 and F substituted
phenylmethylacetylene also undergo the hydrosilylation to give
the syn-addition products in high yields (84~90%), and the
selectivity for the α-(E) products are also high (91~94%). Scheme
2 shows the pathways for the formation of α-(E) (A) and β-(E) (B)
products. The reaction of phenylethylacetylene with
phenylmethylsilane gave the products in low yield (16%) (Table 2,
entry 8), this is possibly due to the steric effect from the ethyl
group, which hinders the addition of the Sm–H bond of the
catalytic species to the C–C triple bond of the alkyne. Furthermore,
capacity
of
2
to
perform
the
hydrosilylation
of
phenylmethylacetylene with various hydrosilanes (Table 1). The
reaction of phenylmethylacetylene with hexylsilane gave the syn-
addition products in 47% yield in 3 h, the regioselectivity (α-(E) :
β-(E)) is up to 18:1 (Table 1, entry 2). Interestingly, when the
secondary hydrosilanes, diphenylsilane and phenylmethylsilane,
were used, the vinylsilanes were produced in high yields with
excellent stereo- and regio-selectivity (Table 1, entries 3 and 4).
Especially, the reaction of phenylmethylacetylene with
phenylmethylsilane provided the syn-addition products in 94%
yield, and the selectivity for the α-(E) isomer is up to 95%. It
should be noted when phenylmethylsilane was used as the
hydrosilylation reagent, the color of reaction solution kept bark
brown during the catalytic reaction. When phenylsilane was used,
the color of reaction solution was bark brown at beginning, and
then slowly changed into yellow. After the color of reaction
solution changed into yellow, the catalytic reaction stopped,
resulting in a low product yield when phenylsilane was used.
These observations suggested that catalytic active species likely
to be a Sm(II) species; the color of the Sm(III) species is generally
lighter than that of the Sm(II) species. For the reactions of
phenylmethylacetylene with diethylsilane or triphenylsilane, no
hydrosilylation product was observed.
Complex
2
can catalyse the hydrosilylation of 3-
thienylmethylacetylene with phenylmethylsilane, giving the
corresponding α-(E) product in high yield and high selectivity
(Table 2, entry 9). This is surprising, we had thought that the
coordination of thienyl group with rare-earth metal ion would
significantly decrease the catalytic activity. On the hand, the
reaction of 2-thienylmethylacetylene gave the product in very low
yield and selectivity (Table 2, entry 10). The low yield observed in
this reaction can be associated with a 4-member chelating
structure formed by sulphur and carbon atoms from the 2-
thienylmethylacetylene after the addition of the Sm–H bond of the
metal species to the C–C triple bond of the alkyne, which reduces
the
reactivity.
When
3-furylmethylacetylene
and
2-
furylmethylacetylene are used as the substrates, the yields of the
products are lower in comparison with the reactions with 3-
thienylmethylacetylene and 2-thienylmethylacetylene. This is
reasonable as the coordination between furyl oxygen atom and
rare-earth metal ion is generally stronger than that between
thienyl sulphur atom and rare-earth metal ion, and this strong
coordination reduces the reactivity. We have also studied the
hydrosilylation of unsymmetrical internal alkynes containing two
alkyl substituents with phenylmethylsilane, the reactions gave a
complicated mixture. In these cases, the hydrosilylation is slow,
therefore the redistribution of phenylmethylsilane becomes
significant. This redistribution reaction produces new
hydrosilanes, such as methylsilane (MeSiH3), which participate in
the hydrosilylation of alkynes.
Table 1. Hydrosilylation of PhCCMe with various hydrosilanes catalyzed by
complex 2.[a]
1.5 h
3 h
entry
RnSiH4-n
yield
(%)[b]
ratio
(A:B)[b]
yield
(%)[b]
ratio
(A:B)[b]
1
2
3
4
5
6
PhSiH3
HexSiH3
Ph2SiH2
PhMeSiH2
Et2SiH2
24
38
78
83
0
11:1
18:1
19:1
19:1
-
31
47
87
94
0
11:1
18:1
19:1
19:1
-
Table 2. Hydrosilylation of internal alkynes with PhMeSiH2 catalyzed by
complex 2.[a]
Ph3SiH
0
-
0
-
yield
ratio
entry
1
alkyne
[a] Reactions were conducted with 2 mol% of complex 2 in C6D6 at 30 oC. [b]
Determined by quantitative 1H NMR spectroscopy using mesitylene as the
internal standard.
(%)[b]
(A:B)[b]
94
19 : 1
As we mentioned in the introduction, the stereo- and regio-
selective hydrosilylation of unsymmetrical internal alkynes with
secondary hydrosilanes is of interests. Therefore, the
hydrosilylation of various such alkynes with phenylmethylsilane
catalysed by complex 2 were studied (Table 2). The reaction of p-
methyl phenylmethylacetylene with phenylmethylsilane gave the
syn-addition products in 91% yield, and the selectivity for the α-
(E) product is 94%, both yield and selectivity are similar to those
of the reaction of phenylmethylacetylene. When the methyl
2
3
91
98
17 : 1
>30 : 1
4
5
72
90
>30 : 1
12 : 1
3
This article is protected by copyright. All rights reserved.

10.1002/chem.202000342
Chemistry - A European Journal
FULL PAPER
All operations were performed under an atmosphere of argon using
Schlenk techniques or in a nitrogen-filled glovebox. Tetrahydrofuran,
toluene, hexane, [D6]benzene, and [D8]tetrahydrofuran were dried over
Na/K alloy, transferred under vacuum, and stored in the glovebox.
6
7
90
84
16
91
19
44
4.5
16 : 1
11 : 1
>30: 1
13 : 1
2 : 1
6 : 1
-
[14a]
[2e]
8
SmI2(THF)2
,
KCH(SiMe3)2
,
KL
(L
=
and
[MeC(NDipp)CHC(Me)NCH2CH2N(Me)CH2CH2NMe2]−),[12]
alkynes[14b,c] (except phenylmethylacetylene and phenylethylacetylene)
9
were
synthesized
following
the
literature
procedures.
10
11
12
Phenylmethylacetylene and phenylethylacetylene were purchased from
Shanghai Macklin Biochemical Co., Ltd and Shanghai Aladdin Bio-Chem
Technology Co., LTD, respectively. Hydrosilanes and alkynes were dried
over CaH2 and distilled under reduced pressure before use. 1H and 13C{1H}
NMR spectra were recorded on a Varian 400 MHz, a Bruker 400 MHz or
an Agilent 400 MHz spectrometer. Chemical shifts δ were reported in ppm
with references to the residual resonance of the deuterated solvents for
proton and carbon spectroscopies. Elemental analyses were performed by
the Analytical Laboratory of Shanghai Institute of Organic Chemistry.
[a] Reactions were conducted with 2 mol% of complex 2 in C6D6 for 3 h at 30
oC. [b] Determined by quantitative 1H NMR spectroscopy using mesitylene as
the internal standard.
Synthesis
Complex 1: To a THF (2 mL) solution of SmI2(THF)2 (281 mg, 0.51 mmol)
was added a THF (2 mL) solution of KL (216 mg, 0.51 mmol) at room
temperature. The reaction was stirred for 2 hours, resulting in a deep green
solution with grey precipitates. After filtration, the solvent was removed
under vacuum, and the residue was extracted with toluene (25 mL). The
solvent of the extraction was removed under vacuum, and the residue was
washed with hexane (2 mL × 3) and dried under vacuum to give complex
1 as a green solid (210 mg, 62% yield). The complex was paramagnetic.
1H NMR (400 MHz, d8-THF, 25 oC): δ = 14.54, 11.59, 8.94, 8.52, 5.25, 2.70,
1.81, 1.06 ppm; elemental analysis calcd (%) for C48H82I2N8Sm2·2toluene:
C 49.32, H 6.54, N 7.42; found: C 49.50, H 6.37, N 7.36.
Complex 2: To a THF (1.5 mL) of 1 (95 mg, 0.07 mmol) was added a THF
o
(1 mL) of KCH(SiMe3)2 (28 mg, 0.14 mmol) at -35 C. The reaction was
kept at -35 C for 20 minutes, resulting in a deep red solution with grey
Scheme 2. Regioselectivity in the catalytic hydrosilylation of unsymmetrical
internal alkynes with phenylmethylsilane.
o
precipitates. The solvent was removed under vacuum, and the residue was
extracted with hexane (8 mL). The solvent of the extraction was removed
under vacuum to afford complex 2 as a deep red solid (63 mg, 63% yield).
The complex was paramagnetic. 1H NMR (400 MHz, C6D6, 25 oC): δ =
18.36, 14.83, 14.14, 13.85, 12.82, 12.18, 11.46, 9.81, 7.04, 6.01, 4.36,
2.88, 1.28, -2.80, -3.15, -3.50, -3.77, -4.64, -8.32, -15.38, -40.49 ppm;
elemental analysis calcd (%) for C31H60N4Si2Sm: C 53.55, H 8.70, N 8.06;
found: C 53.25, H 8.84, N 8.01.
Conclusion
In summary, a samarium(II) monoalkyl complex was synthesized
by using a β-diketiminato based tetradentate ligand L (L =
[MeC(NDipp)CHC(Me)NCH2CH2N(Me)CH2CH2NMe2]−, Dipp
=
2,6-(iPr)2C6H3) as the supporting ligand. The single-crystal X-ray
crystallography study showed the complex exits as a monomer
with a terminal alkyl ligand, the samarium(II) ion is 5-coordinate
and has a distorted square pyramid coordination geometry. This
samarium(II) monoalkyl complex can efficiently catalyse the
hydrosilylation of various arylmethylacetylenes with secondary
hydrosilanes under mild conditions, and the selectivity for the α-
(E) products is high (91~97%). It can also catalyse the
Typical procedure for the hydrosilylation of alkynes
In a nitrogen-filled glovebox, a C6D6 (200 mg) solution of alkyne (0.5 mmol)
and internal standard mesitylene (0.1 mmol) and a C6D6 (200 mg) solution
of hydrosilane (0.5 mmol) were mixed in a J. Young NMR tube, and then
a C6D6 (100 mg) solution of complex 2 (0.01 mmol) was added at room
temperature. The NMR tube was sealed and immediately taken out of the
o
glovebox, kept in a 30 C oil bath. The yields of hydrosilylation products
were determined by quantitative 1H NMR spectrum after 1.5 or 3 hours.
hydrosilylation
of
3-thienylmethylacetylene
with
phenylmethylsilane, giving the corresponding α-(E) product in
high yield and high selectivity. But when 2-thienylmethylacetylene,
3-thienylmethylacetylene or 2-thienylmethylacetylene was used
as the substrate, the yield and selectivity for the α-(E) products
are low. Synthesis of chiral samarium(II) monoalkyl complexes
and their applications for the regio- and enantio-selective
hydrosilylation of unsymmetrical internal alkynes with aryl and
alkyl-substituted secondary hydrosilanes are under investigation.
X-ray crystallography
Single crystals of 1·2toluene suitable for single-crystal X-ray diffraction
were grown from a toluene solution, and those of 2 were from a hexane
solution.[15] The crystals were mounted under a nitrogen atmosphere on a
glass fibre at low temperature. Data collection of 1·2toluene was
performed on a Bruker APEX-II CCD with graphite-monochromated MoKα
radiation (λ = 0.71073 Å), that of 2 was performed on a Bruker D8 Venture
with GaKα radiation (λ = 1.34139 Å). The SMART program package was
used to determine the unit cell parameters. The absorption correction was
applied using SADABS. The structures were solved by direct methods and
refined on F2 by full-matrix least-squares techniques with anisotropic
thermal parameters for non-hydrogen atoms. Hydrogen atoms were
placed at calculated positions and were included in the structure
Experimental Section
General
4
This article is protected by copyright. All rights reserved.

10.1002/chem.202000342
Chemistry - A European Journal
FULL PAPER
calculation. Calculations were carried out using the SHELXL-2014 and
Olex2 program. The software used is listed in reference.[16]
123, 9216−9217; h) Z. M. Hou, Y. G. Zhang, M. Nishiura, Y. Wakatsuki,
Organometallics 2003, 22, 129−135; i) X. W. Zhang, G. H. Maunder, S.
Gieβmann, R. MacDonald, M. J. Ferguson, A. H. Bond, R. D. Rogers, A.
Sella, J. Takats, Dalton Trans. 2011, 40, 195−210.
a) A. N. Selikhov, T. V. Mahrova, A. V. Cherkasov, G. K. Fukin, L. Maron,
A. A. Trifonov, Chem. Eur. J. 2017, 23, 1436−1443; b) A. N. Selikhov, G.
S. Plankin, A. V. Cherkasov, A. S. Shavyrin, E. Louyriac, L. Maron, A. A.
Trifonov, Inorg. Chem. 2019, 58, 5325−5334; c) A. N. Selikhov, A. S.
Shavyrin, A. V. Cherkasov, G. K. Fukin, A. A. Trifonov, Organometallics
2019, 38, 4615−4624.
a) E. Langkopf, D. Schinzer, Chem. Rev. 1995, 95, 1375−1408; b) T.-Y.
Luh, S.-T. Liu in The Chemistry of Organic Silicon Compounds, Vol. 2
(Eds.: Z. Rappoport, Y. Apeloig), John Wiley & Sons Ltd, Chichester,
1998; pp. 1793−1868
a) I. Ojima, Z. Y. Li, J. W. Zhu in The Chemistry of Organic Silicon
Compounds, Vol. 2 (Eds.: Z. Rappoport, Y. Apeloig), John Wiley & Sons
Crystal data for 0.5(1·2toluene): C31H49IN4Sm, green, Mr = 1509.98,
triclinic, space group P-1, a = 11.144(2), b = 11.433(2), c = 15.096(3), α =
69.945(3), β = 83.330(3), γ = 66.571(2), V = 1657.3(5), Z = 1, MoKα, λ =
0.71073 Å, T = 130 K, R = 0.0431, wR = 0.1066, for 6117 unique reflections
with I > 2σ(I), GOOF = 1.021.
[4]
Crystal data for 2: C31H60N4Si2Sm, red, Mr = 695.36, monoclinic, space
group P21/n, a = 14.9774(4), b = 16.0913(4), c = 15.1412(4), α = 90, β =
91.020(2), γ = 90, V = 3648.54(16), Z = 4, GaKα, λ = 1.34139 Å, T = 130
K, R = 0.0396, wR = 0.0897, for 5636 unique reflections with I > 2σ(I),
GOOF = 1.038.
[5]
[6]
Ltd, Chichester, 1998; pp. 1687−1792; b) Hydronsilylation:
A
Comprehensive Review on Recent Advances (Ed.: B. Marciniec),
Springer, 2009, pp. 53−83; c) D. S. W. Lim, E. A. Anderson, Synthesis
2012, 44, 983−1010.
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (Nos. 21602237, 21732007, 21890721 and
21821002), the Program of Shanghai Academic Research Leader,
the Strategic Priority Research Program of the Chinese Academy
of Sciences (Grant No. XDB20000000), and Fujian Institute of
Innovation, Chinese Academy of Sciences.
[7]
a) B. M. Trost, Z. T. Ball, J. Am. Chem. Soc. 2005, 127, 17644−17655;
b) M. R. Chaulagain, G. M. Mahandru, J. Montgomery, Tetrahedron 2006,
62, 7560−7566; c) Y. Kawasaki, Y. Ishikawa, K. Igawa, K. Tomooka, J.
Am. Chem. Soc. 2011, 133, 20712−20715; d) C. Belger, B. Plietker,
Chem. Commun. 2012, 48, 5419−5421; e) S. T. Ding, L.-J. Song, L. W.
Chung, X. H. Zhang, J. W. Sun, Y.-D. Wu, J. Am. Chem. Soc. 2013, 135,
13835−13842; f) Z. B. Mo, J. Xiao, Y. F. Gao, L. Deng, J. Am. Chem.
Soc. 2014, 136, 17414−17417; g) J. Guo, Z. Lu, Angew. Chem. 2016,
128, 10993−10996; Angew. Chem. Int. Ed. 2016, 55, 10835−10838; h)
A. Rivera-Hernández, B. J. Fallon, S. Ventre, C. Simon, M.-H. Tremblay,
G. Gontard, E. Derat, M. Amatore, C. Aubert, M. Petit, Org. Lett. 2016,
18, 4242−4245; i) H. N. Wen, X. L. Wan, Z. Huang, Angew. Chem. 2018,
130, 6427−6431; Angew. Chem. Int. Ed. 2018, 57, 6319−6323.
a) X. X. Yang, C. Y. Wang, Angew. Chem. 2018, 130, 935−940; Angew.
Chem. Int. Ed. 2018, 57, 923−928; b) H. Liang, Y.-X, Ji, R.-H. Wang, Z.-
Z. Zhang, B. Zhang, Org. Lett. 2019, 21, 2750−2754.
Keywords: alkyl complex • alkynes • hydrosilylation •
homogeneous catalysis • samarium
[1]
a) S. A. Cotton, Coord. Chem. Rev. 1997, 160, 93−127; b) G. A.
Molander, J. A. C. Romero, Chem. Rev. 2002, 102, 2161−2185; c) M.
Zimmermann, R. Anwander, Chem. Rev. 2010, 110, 6194−6259; d) M.
Nishiura, F. Guo, Z. M. Hou, Acc. Chem. Res. 2015, 48, 2209−2220; e)
A. A. Trifonov, D. M. Lyubov, Coord. Chem. Rev. 2017, 340, 10−61.
For ytterbium(II) and europium(II) alkyl complexes, see: a) C. Eaborn, P.
B. Hitchcock, K. Izod, J. D. Smith, J. Am. Chem. Soc. 1994, 116,
12071−12072; b) P. B. Hitchcock, S. A. Holmes, M. F. Lappert, S. Tian,
J. Chem. Soc., Chem. Commun. 1994, 2691−2692; c) J. R. van den
Hende, P. B. Hitchcock, S. A. Holmes, M. F. Lappert, S. Tian, J. Chem.
Soc., Dalton Trans. 1995, 3933−3939; d) C. Eaborn, P. B. Hitchcock, K.
Izod, Z.-R. Lu, J. D. Smith, Organometallics 1996, 15, 4783−4790; e) P.
B. Hitchcock, A. V. Khvostov, M. L. Lappert, J. Organomet. Chem. 2002,
663, 263−268; f) K. Yan, B. M. Upton, A. Ellern, A. D. Sadow, J. Am.
Chem. Soc. 2009, 131, 15110−15111; g) K. Yan, G. Schoendorff, B. M.
Upton, A. Ellern, T. L. Windus, A. D. Sadow, Organometallics 2013, 32,
1300−1316; h) C. Eaborn, M. S. Hill, P. B. Hitchcock, J. D. Smith, S.
Zhang, Organometallics 1999, 18, 2342−2348; i) L. J. Bowman, K. Izod,
W. Clegg, R. W. Harrington, Organometallics 2007, 26, 2646−2651; j) L.
Hasinoff, J. Takats, X. W. Zhang, J. Am. Chem. Soc. 1994, 116,
8833−8834; k) G. M. Ferrence, A. J. Arduengo, A. Jockisch, H.-J. Kim,
R. McDonald, J. Takats, J. Alloy. Compd. 2006, 418, 184−188; l) J. H.
Cheng, J. Takats, M. J. Ferguson, R. McDonald, J. Am. Chem. Soc. 2008,
130, 1544−1545; m) R. Litlabø, K. Saliu, M. J. Ferguson, R. McDonald,
J. Takats, R. Anwander, Organometallics 2009, 28, 6750−6754; n) P. B.
Hitchcock, A. V. Khvostov, M. F. Lappert, A. V. Protchenko, Dalton Trans.
2009, 2383−2391; o) J. Zou, D. J. Berg, A. Oliver, B. Twamley,
Organometallics 2013, 32, 6532−6540.
[8]
[9]
[2]
T. Takahashi, F. Y. Bao, G. H. Gao, M. Ogasawara, Org. Lett. 2003, 5,
3479−3481.
[10] a) G. A. Monlander, W. H. Retsch, Organometallics 1995, 14,
4570−4575; b) G. A. Molander, E. E. Knight, J. Org. Chem. 1998, 63,
7009−7012; c) H. Schumann, M. R. Keitsch, J. Winterfeld, S. Mühle, G.
A. Molander, J. Organometallics 1998, 559, 181−190; d) G. A. Molander,
J. A. C. Romero, C. P. Corrette, J. Organomet. Chem. 2002, 647,
225−235; e) D. S. Levine, T. Don, Tilley, R. A. Andersen, Chem.
Commun. 2017, 53, 11881−11884.
[11] a) E. L. Lu, J. X. Chu, Y. F. Chen, M. B. Borzov, G. Y. Li, Chem. Commun.
2011, 47, 743−745; b) J. X. Chu, E. L. Lu, Z. X. Liu, Y. F. Chen, X. B.
Leng, H. B. Song, Angew. Chem. 2011, 123, 7819−7822; Angew. Chem.
Int. Ed. 2011, 50, 7677−7680; c) J. L. Zhou, J. X. Chu, Y. Y. Zhang, G.
Yang, X. B. Leng, Y. F. Chen, J. L. Zhou, J. X. Chu, Y. Y. Zhang, G. Yan,
X. B. Leng, Y. F. Chen, Angew. Chem. 2013,125, 4337−4340; Angew.
Chem. Int. Ed. 2013, 52, 4243−4246.
[12] X. J. Liu, L. Xiang, E. Louyriac, L. Maron, X. B. Leng, Y. F. Chen, J. Am.
Chem. Soc. 2019, 141, 138−142.
[13] W. F. Chen, H. B. Song, J. F. Li, C. M. Cui, Angew. Chem. 2020, 132,
2385−2389; Angew. Chem. Int. Ed. Engl. 2020, 59, 2365−2369.
[14] a) P. L. Watson, T. H. Tulip, I. Williams, Organometallics 1990, 9,
1999−2009; b) T. Matsuda, S. Kadowaki, M. Murakami, Chem. Commun.
2007, 25, 2627−2629; c) S. Liu, J. Sawicki, T. G. Driver, Org. Lett. 2012,
14, 3744−3747.
[15] CCDC 1979105 (1), CCDC 1979106 (2), contain the supplementary
crystallographic 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.
[3]
For samarium(II) alkyl complexes, see: a) W. Clegg, C. Eaborn, K. Izod,
P. O’Shaughnessy, J. D. Smith, Angew. Chem. 1997, 109, 2925−2926;
Angew. Chem. Int. Ed. Engl. 1997, 36, 2815−2817; b) M. S. Hill, P. B.
Hitchcock, Dalton Trans. 2003, 4570−4571; c) K. Izod, W. Clegg, R. W.
Harrington, Dalton Trans. 2010, 39, 6705−6710; d) A. Pindwal, A. Ellern,
A. D. Sadow, Organometallics 2016, 35, 1674−1683; e) I. Korobkov, S.
Gambarotta, Organometallics 2009, 28, 4009−4019; f) D. Bojer, A.
Venugopal, B. Neumann, H.-G. Stammler, N. W. Mitɀel, Angew. Chem.
2010, 122, 2665−2669; Angew. Chem. Int. Ed. 2010, 49, 2611−2614; g)
Z. M. Hou, Y. G. Zhang, O. Tardif, Y. Wakatsuki, J. Am. Chem. Soc. 2001,
[16] a) G. M. Sheldrick, SADABS, An Empirical Absorption Correction
Program for Area Detector Data, University of Göttingen, Göttingen,
Germany, 1996; b) G. M. Sheldrick, SHELXL-2014, University of
Göttingen, Göttingen, Germany, 2014; c) G. M. Sheldrick, Acta
Crystallogr. Sect. C 2015, 71, 3−8; d) O. V. Dolomanov, L. J. Bourhis, R.
5
This article is protected by copyright. All rights reserved.

10.1002/chem.202000342
Chemistry - A European Journal
FULL PAPER
J. Gildea, J. A. K. Howard, H. Puschmann, J. Appl. Crystallogr. 2009, 42,
339−341. e) SMART, Version 5.628, Bruker AXS Inc., Madison, WI,
2002; f) SAINT+, Vdrsion 6.22a, Bruker AXS Inc., Madison, WI, 2002; g)
SAINT+, Vdrsion v7.68A, Bruker AXS Inc., Madison, WI, 2009; h)
SHELXTL NT/2000, Version 6.1, Bruker AXS Inc., Madison, WI, 2002.
6
This article is protected by copyright. All rights reserved.

10.1002/chem.202000342
Chemistry - A European Journal
FULL PAPER
Entry for the Table of Contents
A five-coordinate samarium(II) monoalkyl complex is synthesized and structurally characterized. This complex shows high catalytic
activity and high stereo- and regio-selectivity in hydrosilylation of various aryl and methyl-substituted unsymmetrical internal alkynes
with secondary hydrosilanes under mild conditions.
7
This article is protected by copyright. All rights reserved.