Coordination Features of the 1,3,5-Triazapentadienyl Ligand in Alkyl Complexes of Rare-Earth Metals

Article abstract of DOI:10.1002/ejic.202100250

The reactions of 1,3,5-triazapentadiene 2,6-iPr₂C₆H₃NC(Ph)NC(Ph)NHC₆H₃iPr₂-2,6 (1) with Ln(CH₂SiMe₃)₃(THF)₂ (Ln=Y, Lu) in hexane afford bis(alkyl

Full text of DOI:10.1002/ejic.202100250

European Journal of Inorganic Chemistry
Accepted Article
Title: Coordination features of 1,3,5-triazapentadienyl ligand in alkyl
complexes of rare-earth metals
Authors: Natalia Rad’kova, Tatyana Kovylina, Anton Cherkasov,
Konstantin Lyssenko, Anatoly Ob’edkov, and Alexander
Trifonov
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: Eur. J. Inorg. Chem. 10.1002/ejic.202100250
Link to VoR: https://doi.org/10.1002/ejic.202100250
01/2020

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
Coordination features of 1,3,5-triazapentadienyl ligand in alkyl
complexes of rare-earth metals
Natalia Yu. Rad’kova,[a] Tatyana A. Kovylina,[a] Anton V. Cherkasov,[a] Konstantin A. Lyssenko,[b],[c]
Anatoly M. Ob’edkov[a] and Alexander A. Trifonov*[a],[b]
[a]
Mrs. Natalia Yu. Rad’kova, Dr. Tatyana A. Kovylina, Mr. Anton V. Cherkasov, Dr. Anatoly M. Ob’edkov and Prof. Dr. Alexander A. Trifonov
Institute of Organometallic Chemistry of Russian Academy of Sciences
Tropinina Street 49, GSP-445, 603950, Nizhny Novgorod, Russia
E-mail: trif@iomc.ras.ru
[b]
[c]
Prof. Dr. Konstantin A. Lyssenko, Prof. Dr. Alexander A. Trifonov
Institute of Organoelement Compounds of Russian Academy of Sciences
Vavilova Street 28, 119334, Moscow, Russia
Prof. Dr. Konstantin A. Lyssenko
M.V. Lomonosov Moscow State University, Chemistry Department
Leninskie Gory, 119991 Moscow, Russia
Supporting information for this article is given via a link at the end of the document.
Abstract:
The
reactions
of
1,3,5-triazapentadiene
(1)
2,6-
with
discovered over a century ago, however their coordination
chemistry with rare-earths still remains virtually unexplored.[13]
iPr2C6H3NC(Ph)NC(Ph)NHC6H3iPr2-2,6
Ln(CH2SiMe3)3(THF)2 (Ln = Y, Lu) in hexane afford bis(alkyl)
complexes [2,6-iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2-
2,6]Ln(CH2SiMe3)2(THF) (Ln =Y (2), Lu (3)) in 58 (2) and 62 (3) %
N
N
N
N
N
N
or
N
N
yields. The X-ray diffraction study revealed that in
3 the
triazapentadienyl ligand coordinates with the Lu3+ ion in “amidinate”
fashion resulting in the formation of a four-membered metallocycle.
-
dik
β
e o m na es
i i
t t
- r aza en a enes
1 3 5 t i
di
, ,
t
,
p
Figure 1. Key structural motifs of 1,3,5-triazapentadienes (tap) and
isoelectronic counterpart β-diketoiminate.
In contrast, the reaction of
1 with the scandium analogue
Sc(CH2SiMe3)3(THF)2 in toluene proceeds with the cleavage of C-N
bond of 1,3,5-triazapentadiene and leads to the formation of a
dinuclear
monoalkyl
complex
[{μ2-2,6-
Taps are polyfunctional nitrogen-containing analogues of
pentadienes having unsaturated NCNCN fragment formed by
formally fused amidine, imide and amine functions, capable of
saturation of the metal center coordination environment.[13a]
1,3,5-Triazapentadienyl ligands have many advantages, such as
large variety of possibilities for their geometry design and
modification of steric and electronic properties by introducing
different substituents onto nitrogen and carbon atoms of the
NCNCN fragment. In addition, 1,3,5-triazapentadienyl ligands
have three basic nitrogen sites for coordination with metal ion[14]
(Fig. 2). However, no example of the application of 1,3,5-
triazapentadienyl ligands in the synthesis of rare-earth metal
complexes is known so far.
iPr2C6H3NC(Ph)N}Sc(CH2SiMe3)(THF)]2 (4) in 43% yield. Complex
4 features κ2-N,N-coordination of the residual dianionic {μ2-2,6-
iPr2C6H3NC(Ph)N}2- ligand μ-bridging two Sc3+ centers. Alkyl
complexes 2–4 were evaluated as pre-catalysts for isoprene
polymerization and hydrosilylation of unsaturated substrates with
PhSiH3.
Introduction
The rational design of new ligand systems suitable for
coordination to large ions[1] of electropositive[2] rare-earth metals
which can allow for the synthesis of isolable complexes is still in
the focus of organometallic and coordination chemistry of these
elements.[3] Due to the hard Lewis acidity of rare-earth metals,
polydentate N-containing ligands seem to be prospective and
promising candidates for strong binding with these ions[3b,4] able
to provide kinetic stability of their complexes. Indeed, a variety of
N-containing ligands was successfully employed for the
R2 R2
N
R2 R2
N
R2 R2
N
R2
R1
N
R2
R1
M
R1
R1
N
N
N
N
N
N
N
N
R1
R1
R1
R1
n
L
M
M
resen wor
t
P
k
-s a e
h
d
-s a e
h
d
p
-
U
erm na
W
p
k1 N t
i
l
n
a e
t t
a
“ m
idi
e
”
yp
(
)
synthesis
alkyl,[3d,6] hydrido,[3a,7] borohydrido derivatives[8] of rare-earth
metals. To date,
of
highly
reactive
alkyl,[3a,3d,5]
cationic
Figure 2. The coordination types of 1,3,5-triazapentadienyl ligands.
amidinate,[3c,3d,9] guanidinate,[3a,3c,10] amidopyridinate[11] and β-
diketoiminato[3c,12] ligands are among those which are most
frequently and efficiently used in rare-earth chemistry. Strangely,
despite the similarity of structural and electronic properties of β-
diketoiminates (Fig. 1) and 1,3,5-triazapentadienes (also known
as imidoylamidines) the latter remain completely beyond rare-
earth chemistry and nothing was known about their coordination
to large ions of these metals. 1,3,5-Triazapentadienes (tap) were
We report here on the synthesis and characterization of rare-
earth alkyl complexes coordinated by 1,3,5-triazapentadienyl
ligand. The synthesized compounds were scrutinized as pre-
catalysts in reactions of isoprene polymerization and
hydrosilylation of multiple C‒C bonds.
Results and Discussion
1
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
Synthesis and characterization of complexes 2-4
The bright-yellow crystals of complex 3 suitable for X-ray
1,3,5-Triazapentadiene
2,6-
diffraction study were obtained by continuous cooling of the
iPr2C6H3NC(Ph)NC(Ph)NHC6H3iPr2-2,6 (1) was synthesized
according to the previously published method developed by Ley
and Müller[15] in 1907. For the synthesis of bis(alkyl) rare-earth
complexes supported by 1,3,5-triazapentadienyl ligand the
alkane elimination approach was employed. The preparative-
scale reactions of Ln(CH2SiMe3)3(THF)2 (Ln = Y, Lu) with
equimolar amounts of 1 were carried out at 0°C in hexane and
hexane solution at −20 °C. Complex 3 crystallizes in
orthorhombic Pbca space group with unique molecule of
complex in the asymmetric unit (Fig. 3). The crystallographic
data and structure refinement details are given in Table 1.
afforded
bis(alkyl)
derivatives
[2,6-
iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2-2,6]Ln(CH2SiMe3)2(THF)
(Ln = Y (2), Lu (3)) (Scheme 1). Bis(alkyl) complexes 2 and 3
were isolated as bright-yellow microcrystalline solids in 58 and
62 % yields, respectively. Complexes 2 and 3 are air-and
moisture-sensitive, well-soluble in benzene, toluene and hexane.
Ph
C
Ph
C
r
r
iP
iP
HN
r
iP
r
iP
N
N
N
N
r
iP
3
r
H
0 °
C
ex
,
r
iP
iP
+
n
e
)
3
L
CH SiM 3THF2
(
2
-
TMS
r
iP
n
C
C
L
THF
SiM
3
Ph
Ph
N
e
e
SiM
n =
u
3
(
L
Y
2
(
58
L
62
%
)
%;
)
Scheme 1. Synthesis of 2 and 3.
The complexes 2 and 3 were characterized by H and 13C{1H}
spectroscopy. In the H NMR spectra of 2 and 3, the methylene
1
Figure 3. Molecular structure of 3. Thermal ellipsoids are drawn at the 30%
probability level. Me groups of the iPr substituents, CH2 fragments of THF
molecule and all hydrogen atoms are omitted for clarity.
1
protons of the alkyl groups attached to the metal ion appear as
broadened singlets at −0.20 and −0.29 ppm, respectively. In
the 13C{1H} spectrum, the appropriate carbons give rise to a
doublet at 37.1 (1JY,C = 38.4 Hz) for 2, while for the lutetium
complex 3 they appear as a singlet at 46.3 ppm (see
Experimental section for NMR details and Figs. S1‒S4). The
methyl protons of SiMe3 groups give rise to the singlets in the 1H
NMR spectra of complexes 2 and 3 with chemical shifts 0.36 (2)
and 0.37 (3) ppm, respectively. Two doublets with chemical
shifts δ 0.98 (3JH-H = 6.8 Hz), 1.32 (3JH-H = 6.8 Hz) (for 2) and δ
1.01 (3JH-H = 5.6 Hz), 1.23 (3JH-H = 5.6 Hz) (for 3) ppm
correspond to the methyl protons of iPr groups. The methine
hydrogen atoms of the iPr groups appear as one septet at 3.45
(3JH-H = 6.8 Hz) ppm for 2 and one multiplet at 3.37 ppm for 3.
The aromatic region of the spectrum of 2 contains a pattern of
The X-ray single crystal diffraction study of compound 3
revealed that the lutetium atom is bound with two nitrogen atoms
of 1,3,5-triazapentadienyl ligand, two carbon atoms of the alkyl
groups and one oxygen atom of the THF molecule. Thus, the
formal coordination number of Lu cation is 5. It should be noted
that in 3 an unusual bonding mode of the 1,3,5-triazapentadienyl
ligand with metal ion is realized. In complexes of transition
metals, the tap ligands either coordinate to metal centers in κ2-
N,N mode forming six-membered NCNCNM metallocycles[16] or
bind only via one nitrogen atom in κ1-N fashion resulting in W–
shaped type or linear structures.[17] In contrast, in complex 3
previously unknown κ2-N,N’-amidinate type of coordination of the
tap ligand was discovered. Only two neighboring nitrogen atoms
are involved into the metal-ligand interaction leading to the
formation of a four-membered metallocycle, while the attached
imino group remains pendant. The alkyl groups are arranged on
opposite sides from the LuNCN plane; apparently, to minimize
the interaction with 2,6-iPr2C6H3 group. The Lu–N bonds in 3
(Lu(1)-N(1) 2.371(3) Å, Lu(1)-N(2) 2.264(3) Å) fall into the range
typical for lutetium complexes supported by amidinate ligands
two multiplets at δ 6.60 and 7.00 ppm, a triplet at δ 6.67 (3JH–H
=
7.5 Hz) ppm and a doublet at δ 7.10 (3JH–H = 7.5 Hz) ppm. In the
case of 3, aromatic protons appear as a set of multiplets in the
low field region (6.71–7.34 ppm).
Thermostabilities of diamagnetic bis(alkyl) complexes 2 and 3
were evaluated. Complex
3
demonstrated rather good
thermostability (in the scale appropriate for hydrocarbyl
derivatives of rare-earths): in dry and degassed benzene-d6
solution at room temperature no apparent decomposition was
detected during 2 months. However, when heated in a benzene-
d6 solution to 60 °C 3 has a half-life time of 6 h. Yttrium complex
2 was found to be less stable with half-life time about 12 hours
at 25 °C in benzene-d6 solution. The process of decomposition
of 2 is accompanied by the color change from yellow to bright
red. Decompositions of 2 and 3 occur with the elimination of
SiMe4, unfortunately all the trials to isolate any metal containing
products failed.
[CyC(N-2,6-iPr2C6H3)2]Lu(CH2SiMe3)2(THF)
(2.317(3),
{2-[Ph2P=O]C6H4NC(tBu)N(2,6-
2.308(3)
Å);[18]
iPr2C6H3)}Lu(CH2SiMe3)2 (2.361(3), 2.343(3) Å).[9b] However,
unlike the most amidinate complexes in which M-N bonds have
close lengths, in 3 these bonds differ noticeably similarly to
lutetium
complex
2,6-
iPrC6H3NC(C6H5)NHCH2CH2(NCHCHN(C6H2Me3-
2,4,6)CH)Lu(CH2SiMe3)2 (2.352(3), 2.260(4) Å)[19]. At the same
time, the C-N bond lengths in the amidinate fragment also
2
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
slightly differ from each other (C(1)-N(1) 1.322(5) Å, C(1)-N(2)
1.357(5) Å), but still indicate delocalization of negative charge
along the NCN fragment. The four-membered LuNCN cycle in 3
adopts nearly planar structure – the dihedral angle between the
NLuN and NCN planes is 168.1(5)°.
Although all our attempts to obtain crystals of 2 suitable for X–
ray studies failed, the composition of the complex was
unambiguously determined by means of spectroscopic methods
and microanalysis (see ESI).
Similarly to 2 and 3, the alkane elimination approach was used
for the synthesis of bis(alkyl) complex of scandium. Surprisingly,
the reaction of 1 with Sc(CH2SiMe3)3(THF)2 in toluene at 20 °C
is accompanied by the cleavage of one C−N bond of 1,3,5-
triazapentadiene and affords a dimeric mono(alkyl) complex [{μ2-
iPr2C6H3NC(Ph)N}Sc(CH2SiMe3)(THF)]2 (4) coordinated by μ2-
bridging dianionic amidinate ligand (Scheme 2). Compound 4
was isolated in 43% yield as highly air- and moisture-sensitive
Table 1. Selected bond lengths (d) and bond angles (ω) in complexes 3 (Lu)
and 4 (Sc)*.
Compound
Bond
d/Å
Angle
ω/deg
3
Lu(1)-N(1)
Lu(1)-N(2)
N(1)-C(1)
2.371(3)
2.264(3)
1.322(5)
1.357(5)
1.390(5)
1.270(5)
1.414(5)
2.390(7)
2.275(7)
2.275(3)
2.242(2)
2.185(2)
2.031(2)
2.229(2)
2.171(2)
3.1189(6)
1.354(2)
1.321(2)
N(2)-Lu(1)-N(1)
C(39)-Lu(1)-N(1)
C(43)-Lu(1)-N(1)
C(39)-Lu(1)-N(2)
C(43)-Lu(1)-C(39)
N(1)-C(1)-N(2)
N(3)-C(20)-N(2)
C(1)-N(1)-C(8)
C(1)-N(2)-C(20)
C(20)-N(3)-C(27)
N(1)–Sc(1)–N(2)
N(2)–Sc(1)–N(2A)
N(1)–Sc(1)–C(20)
N(2)–Sc(1)–C(20)
N(1)–C(1)–N(2)
C(1)–N(1)–C(8)
57.9(2)
light-yellow
crystals.
The
reactions
of
1
with
101.9(2)
107.7(2)
101.5(2)
107.5(2)
113.9(3)
117.1(3)
121.0(3)
121.6(3)
122.8(3)
62.52(5)
84.64(6)
112.27(6)
115.86(6)
118.4(2)
122.9(2)
Sc(CH2SiMe3)3(THF)2 in toluene at -78 °C and in THF also
afforded 4.
N(2)-C(1)
iPr
iPr
HN
Ph
C
Ph
C
iPr
iPr
iPr
N
N
C
+
N
N
20 °C
iPr
Tol,
-
N(2)-C(20)
N(3)-C(20)
N(3)-C(27)
Lu(1)-C(39)
Lu(1)-C(43)
Lu(1)-O(1)
Sc(1)–N(1)
Sc(1)–N(2)
Sc(1)–N(2A)
Sc(1)–C(20)
Sc(1)–O(1)
Sc(1)…Sc(1A)
C(1)–N(1)
C(1)–N(2)
iPr
iPr
Ph
TMS
THF
C
Sc
Ph
N
Me3Si
SiMe3
SiMe3 3THF2
)
Sc(CH2
iPr
N
THF
Sc
SiMe3
iPr
C
N
iPr
Sc
N
N
iPr
0.5
THF
C
SiMe3
4
(43%)
4
iPr C H
SiMe3
+
2,6-
3N=C(Ph)CH2
6
2
Scheme 2. Synthesis of 4.
The isolated complex 4 proved to be thermally stable: in
benzene-d6 solution at 20 °C no evidence of decomposition was
observed during 2 weeks. Even after heating 4 at 60 °C during 6
h (benzene-d6,) no decomposition took place. In the 1H NMR
spectrum of 4, the methylene protons of the CH2SiMe3 appear
as two broad peaks at 0.50 and 0.55 ppm. The carbons from the
same methylene fragments give rise to a slightly broadened
singlet in the 13C NMR spectrum of 4 at δC = 47.0 ppm (see
Experimental section for NMR details and Figs. S5‒S6). The
*)Symmetry transformations used to generate equivalent atoms in 4 is #1 -
x+2,-y+1,-z
1
methyl protons of SiMe3 groups give rise to a singlet in the H
The Lu–C bonds lengths in 3 ((2.275(7)-2.390(7) Å) are
NMR spectrum with chemical shift 0.35 ppm. The methyl protons
of the iPr groups give rise to two doublets at 0.99 (3JH-H = 6.8
Hz) and 1.26 (3JH-H = 6.8 Hz) ppm. The methine hydrogen atoms
of the iPr groups appear as one septet at 3.40 (3JH-H = 6.8 Hz)
ppm. The aromatic region of the spectrum contains a pattern of
doublet at δ 7.35 (3JH-H = 8.2 Hz) ppm and two multiplets at δ
7.00 and in the range of δ 6.64–6.84 ppm.
The NMR scale reaction of 1 with Sc(CH2SiMe3)3(THF)2
performed in benzene-d6 at room temperature allowed to
observe (besides the signals of 4 mentioned above) additional
comparable to the values previously measured in the related
complexes
(2.328(4),
[CyC(N-2,6-iPr2C6H3)2]Lu(CH2SiMe3)2(THF)
2.327(4) [2,6-
Å);[18]
iPrC6H3NC(C6H5)NHCH2CH2(NCHCHN(C6H2Me3-
2,4,6)CH)]Lu(CH2SiMe3)2 (2.337(5), 2.359(5) Å),[19] {2-
[Ph2P=O]C6H4NC(tBu)N(2,6-iPr2C6H3)}Lu(CH2SiMe3)2
(2.317(4), 2.360(4) Å).[9b] The Lu–O bond length in 3 (2.275(3)
Å) is close to the distances in the formerly reported five-
coordinate
compounds
CyC(N-2,6-
(2.315(3)
Å);[18]
iPr2C6H3)2]Lu(CH2SiMe3)2(THF)
[NPN]Lu(CH2SiMe3)(THF) (2.303(2) Å).[20]
peaks
iPr2C6H3N=C(Ph)CH2SiMe3
supposedly proceeds via the formation of
corresponding
to
the
by-product
ESI). The
2,6-
reaction
bis(alkyl)
(see
It is noteworthy that, despite specific type of coordination of the
tap ligand in crystalline state, in the 1H NMR spectrum of
complex 3 in benzene-d6 the ligand appears as a single set of
signals. The variable temperature 1H NMR study of 3 in toluene-
d8 in the temperature range 213-293 K did not reveal dynamic
process, most likely due to its high rate in NMR time-scale.
a
intermediate (Scheme 2), however, no evidence of this was
1
obtained by means of H NMR spectroscopy. A molecular peak
with m/z 351.6 corresponding to iPr2C6H3NC(Ph)CH2SiMe3 was
detected in the mass spectrum of the reaction mixture after
isolation of crystals of 4 (see ESI).
3
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
Slow concentration of the saturated toluene solution of 4 at room
temperature allowed for obtaining samples suitable for single
crystal X-ray diffraction study. Complex 4 crystallizes in triclinic
P-1 space group with two structurally independent molecules in
the unit cell. Each of the molecules is located at the inversion
center. The geometric parameters of the molecules are close to
each other, so below we discuss the bond lengths and angles of
only one of them. X-ray analysis revealed that 4 adopts a
dimeric structure (Fig. 4). Each scandium atom is bound with
three nitrogen atoms of two amidinate groups: two of one
chelating κ2-amidinate ligand, and one µ2-bridging nitrogen atom
of other amidinate ligand. Moreover, Sc3+ is bound with one
carbon atom of the alkyl group and an oxygen atom from a THF
molecule. Thus, the formal coordination number of scandium
cation is five.
Catalytic activity of complexes 2-4 in isoprene
polymerization and hydrosilylation of double and triple C-C
bonds
Cis-1,4 stereoregular polyisoprene (PIP) is known as one of the
most important elastomers used for production of tires and other
elastic materials. Generally, single-component neutral organo-
rare-earth compounds are inactive in polymerization of
conjugated dienes.[24] However, in the presence of co-catalysts,
such as aluminum alkyls and organoborates, highly reactive
initiator systems for regio- and/or stereoselective polymerization
of conjugated dienes are formed.[11a,25] Structure and electronic
properties of the “supporting” ligands, ion size and nature of
lanthanide metal as well as co-catalysts are among the factors
dramatically affecting both activity and selectivity of the catalytic
systems and proved to be useful tools for providing control of the
polymerization.[24a,25a,26]
Catalytic activity of complexes 2–4 in isoprene polymerization
was evaluated at room temperature in toluene. The results of the
catalytic tests are summarized in Table 2. The complexes 2–4,
as well as the binary systems 2–4/AliBu3, 2–4/[Ph3C][B(C6F5)4],
2–4/[PhNHMe2][B(C6F5)4] performed no activity. However,
when 2 and 3 were activated with borate ([Ph3C][B(C6F5)4] or
[PhNHMe2][B(C6F5)4]) and AliBu3 (1:1:10 molar ratio) (Table 2,
Entries 3–5, 7–9,12–14, 16–18) the resulting ternary systems
were found to enable isoprene polymerization and to provide
91–100% conversion of 10000 equiv. of monomer within the
period of 24 h (Scheme 3).
s
a
com ex
l
p
m n
o o
m
x
bi lk
l
alk
l
y
co le
y
p
(
)
(
)
Ph
C
Ph
C
r
r
r
iP
iP
iP
THF
e
S
iM
3
C
N
N
N
r
iP
c
S
N
N
r
iP
r
iP
r
iP
n
L THF
c
S
N
iP
N
r
THF
e
SiM
3
e
3
C
Figure 4. Molecular structure of 4. Thermal ellipsoids are drawn at the 30%
probability level. Me groups of the iPr substituents, CH2 fragments of THF
molecules and all hydrogen atoms are omitted for clarity.
L
n
=
u
Y L
,
SiM
e
3
SiM
u
p
o
e u v.
10000 i
q
t
The bond lengths between Sc ions and nitrogen atoms of
chelating κ2-amidinate ligand in 4 are noticeably different
(2.185(2) and 2.242(2) Å), but both have values close to those
measured in the related scandium complex [PhC(NC6H3iPr2-
2,6)2]Sc(CH2SiMe3)2(THF) (2.198(2) and 2.215(2) Å).[21] As in 3,
the C-N bond lengths in the amidine fragment also slightly differ
from each other 1.321(2), 1.354(2) Å. The four-membered
ScNCN cycle in 4 adopts nearly planar structure – the dihedral
angle between the NScN and NCN planes is 166.2(2)°.
n
n
c s -
se ec v
c s
-
i
1 4
,
se ec v
i
1 4
l
ti it
,
l
ti it
y
y
.
u
p
o
t
.
98 4%
u
p
o
=
t
92 3%
−
−
.
.
=
.
.
PDI 1 9 3 5
PDI 3 2 5 9
Scheme 3. Selective polymerization of isoprene catalyzedby ternary systems
(2-4)/borate/AliBu3.
It should be noted that complex 4 also contains the μ2-Sc–N
bonds (2.031(3) Å), which are significantly shorter than the Sc–
Namidinate bonds. The μ2-Sc–N bond lengths in 4 (2.031(2) Å) are
shorter than the values measured in dimeric scandium complex
Mono(alkyl) scandium complex 4 provides higher reaction rate:
when the ternary systems containing 4 (4/[Ph3C][B(C6F5)4],
[PhNHMe2][B(C6F5)4]/10AliBu3) were applied, only 0.2-1.0 h
were needed to convert into a polymer 10000 equivalents of
monomer with quantitative conversions (see Table 2, Entries
21–23, 25–27).
The systems 2–3/[Ph3C][B(C6F5)4], [PhNHMe2][B(C6F5)4]/10
AliBu3 afford the PIPs having similar microstructures,
predominantly composed of cis-1,4 and 3,4-units (see Entry 3–5,
7–9, 12–14, 16–18). No trans-1,4 units were detected in the
synthesized PIPs. The ternary catalytic systems (2–
3/[Ph3C][B(C6F5)4], [PhNHMe2][B(C6F5)4]/10AliBu3) provide
the formation of polymers featuring moderate molecular weight
distributions (Mw/Mn = 1.9–3.5). It is noteworthy that the system
(2/[PhNHMe2][B(C6F5)4]/10AliBu3) provides content of cis-1,4
comprising
µ3-bridging
nitrogen
atom
[MeC(N(2,6-
(iPr)2C6H3))CHCMe(NCH2CH2NMe)ScNH(2,6-(iPr)2C6H3)]2
(2.205(3) and 2.212(3) Å).[22] The Sc–C bond lengths in 4
(2.229(2) Å) is comparable with those found in pentacoordinate
scandium
amidopyridinate
bis(alkyl)
derivatives
coordinated
(2.207(4)
by
and
Ap*Sc(CH2SiMe3)2(THF)
2.229(4) Å)[23] and benzamidinate ligands [PhC(NC6H3iPr2-
2,6)2]Sc(CH2SiMe3)2(THF) (2.195(3) and 2.229(3) Å).[21] The
Sc–O bond distance in 4 (2.171(2) Å) is close to the distance
measured in the formerly reported five-coordinate compounds
Ap*Sc(CH2SiMe3)2(THF) (2.194(3) Å)[23] [PhC(NC6H3iPr2-
2,6)2]Sc(CH2SiMe3)2(THF) (2.203(2) Å).[21]
4
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
units up to 89.5% (Entries 3–5). The use of [Ph3C][B(C6F5)4]
leads to a slight decrease of cis-1,4 selectivity to 81.5% (Entries
Table 2. Catalytic tests in isoprene polymerization initiated by systems (2–4)/borate/AliBu3. (borate: [Ph3C][B(C6F5)4] (TB), [PhNHMe2][B(C6F5)4] (HNB),
[Ln]/[borate]/[AliBu3] = 1/1/10).[a]
[c]
Entry
1
Cat
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
[Ln]/[IP]
1/1000
1/1000
1/1000
1/5000
1/10000
1/1000
1/1000
1/5000
1/10000
1/1000
1/1000
1/1000
1/5000
1/10000
1/1000
1/1000
1/5000
1/10000
1/1000
1/1000
1/1000
1/5000
1/10000
1/1000
1/1000
1/5000
1/10000
Borate
―
AlR3
t(h)[b]
48
48
1
Conv. (%)
trace
trace
100
100
100
trace
98
Mn×10-3[c]
―
Mw/Mn
1,4-cis (%)[d]
―
1,4-trans (%)[d]
3,4 (%)[d]
―
AliBu3
―
―
―
―
―
―
―
―
―
―
―
―
―
―
―
―
―
―
―
―
―
―
4.9
4.5
2.9
―
7.9
8.7
3.9
2
HNB
HNB
HNB
HNB
TB
―
―
―
―
3
AliBu3
AliBu3
AliBu3
―
24.7
91.5
152.5
―
2.4
2.6
2.0
―
73.3
77.4
89.5
―
26.7
22.6
10.5
―
4
4
5
48
48
1
6
7
TB
AliBu3
AliBu3
AliBu3
AliBu3
―
52.2
74.3
93.1
―
2.1
2.0
1.9
―
79.5
79.9
81.5
―
20.5
20.1
18.5
―
8
TB
4
100
100
trace
trace
91
9
TB
24
48
48
1
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
―
HNB
HNB
HNB
HNB
TB
―
―
―
―
AliBu3
AliBu3
AliBu3
―
92.2
291.3
471.1
―
3.1
3.5
3.0
―
66.3
77.9
98.4
―
33.7
22.1
1.6
4
100
100
trace
99
24
48
1
―
TB
AliBu3
AliBu3
AliBu3
AliBu3
―
85.8
178.4
248.3
―
2.3
2.2
2.1
―
67.2
82.6
94.9
―
32.8
17.4
5.1
TB
4
100
100
trace
trace
92
TB
24
48
48
0.2
0.5
1
―
―
HNB
HNB
HNB
HNB
TB
―
―
―
―
AliBu3
AliBu3
AliBu3
―
133.5
469.8
871.6
―
5.5
3.4
5.5
―
87.7
90.1
92.3
―
7.4
95
5.4
100
trace
90
4.8
48
0.2
0.5
1
―
TB
AliBu3
AliBu3
AliBu3
125.6
493.7
955.9
5.9
3.2
5.6
78.3
81.8
88.9
13.8
9.5
TB
93
TB
99
7.2
[a] Conditions: complex (10 μmol) in toluene, [M]:[Borate]:[AliBu3] = 1/1/10, (T = 20 °C, Borate: [Ph3C][B(C6F5)4] (TB), [PhNHMe2][B(C6F5)4] (HNB)). [b] Reaction
times are not optimized. [c]Mn determined by GPC against polystyrene standard. [d]Determined by 1H NMR and 13C{1H} NMR spectroscopy in CDCl3 at rt.
7–9). Lutetium complex 3 turned out to be more selective than
its yttrium counterpart 2. The system
(3/[PhNHMe2][B(C6F5)4]/10 AliBu3) allows to obtain PIPs
containing up to 98.4% of cis-1,4 units, therefore providing the
best selectivity (Entries 12–14).
systems including bis(alkyl) yttrium and lutetium complexes
make it possible to obtain polymers with molecular weights
85.8–471.1×103 for complex 3 and 24.7–152.5×103 for complex
2. The ternary catalytic systems based on mono(alkyl) complex
4, unlike bis(alkyl) complexes 2 and 3, afford polymeric chains
composed of cis-1,4, trans-1,4 and 3,4-units (see Entries21–23,
25–27). These ternary catalytic systems (4/[Ph3C][B(C6F5)4],
Application of [Ph3C][B(C6F5)4] provides polyisoprenes with the
cis-1,4 units content up to 94.9% (Entries 16–18). Ternary
5
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
[PhNHMe2][B(C6F5)4]/10AliBu3) produce polymer samples with
relatively broad molecular weight distribution (Mw/Mn = 3.2–5.9).
was observed. The 11B NMR spectrum of this reaction mixture
presents a single singlet at δ −15.9 ppm. All these findings are in
agreement with the previously proposed scheme.[25b,26c,27]
After hydrolysis of the reaction mixture the parent 1,3,5-
Ternary catalytic systems based on compound
(4/[Ph3C][B(C6F5)4], [PhNHMe2][B(C6F5)4]/10AliBu3)
demonstrate rather high cis-1,4 selectivity (78.3–92.3%).
Polymer samples obtained with the system
4
triazapentadiene
iPr2C6H3NC(Ph)NC(Ph)NHC6H3iPr2
was
isolated in quantitative yield, no product of alkylation of the
pendant C=N bond resulting from the addition of AliBu3 was
detected in the reaction mixture.
It should be noted that the ternary systems 2–
4/[Ph3C][B(C6F5)4]/10AliBu3 were inactive in the polymerization
of α-olefins.
Hydrosilylation of alkenes is an important approach for the
production of organosilanes[28] and during the past three
decades the possibility of application of rare-earth metal
complexes for catalysis of this transformation was extensively
studied.[29] Alkyl, hydrido and amido rare-earth complexes
(4/[Ph3C][B(C6F5)4]/10 AliBu3) contain up to 88.9% of cis-1,4
units (Entries 25–27). In the case of the catalytic system with
[PhNHMe2][B(C6F5)4], the content of cis-1,4 units is somewhat
higher (92.3%) (Entries 21–23). The ternary systems containing
compound 4 make it possible to obtain polyisoprenes with high
molecular weights (125.6–955.9×103). In the case of compounds
2–4, the nature of the borate also had a significant influence on
the molecular weight distribution of the resulting polyisoprene. In
the case of complexes 2 and 3, switching from [Ph3C][B(C6F5)4]
to [PhNHMe2][B(C6F5)4] leads to the increase in the
polydispersity index from 2.1 to 2.6 (for 2, Table 2, Entries 3‒5,
7–9) and from 2.3 to 3.5 (for 3, Table 2, Entries 12–14, 16–18).
However, in the case of 4 we observed the opposite pattern: the
replacement of [PhNHMe2][B(C6F5)4] with [Ph3C][B(C6F5)4]
leads to the slight increase in the polydispersity index from 5.5 to
5.9 (Table 2, Entries 21‒23, 25‒27). Ternary catalytic systems
(2–4/[Ph3C][B(C6F5)4], [PhNHMe2][B(C6F5)4]/10AliBu3) enable
regio- and stereoselective polymerization process allowing for
the formation of polyisoprenes containing predominantly cis-1,4-
units (66.3–98.4%). In our previous studies, bis(alkyl) complexes
{2-[Ph2P꞊O]C6H4NC(tBu)N(2,6-iPr2C6H3)}Ln(CH2SiMe3)2 (Ln =
Y, Lu, Er) coordinated by tridentate amidinate ligand were
supported by
a
variety of cyclopentadienyl and “post-
metallocene” ligands demonstrated their high potential as pre-
catalysts of this useful reaction.[28e,29b]
Table 3. Hydrosilylation of styrene with PhSiH3 catalyzed by complexes 2–4.
Optimization of the reaction conditions.[a]
SiH2Ph
mo
l
%
-
2 4
2
+
+
PhSiH3
SiH2Ph
investigated.[9b]
[Ph2P꞊O]C6H4NC(tBu)N(2,6-iPr2C6H3)}Ln(CH2SiMe3)2/
Ternary
systems
({2-
[Ph3C][B(C6F5)4], [PhNHMe2][B(C6F5)4]/10AliBu3) allow to
reach quantitative conversion of up to 10000 equiv. of monomer
with higher reaction rate (2 h) compared to the systems based
on complexes 2 and 3. The catalytic systems based on
1
2
2
2
2
2
2
2
2
2
3
3
3
3
4
4
4
4
4
1
6
benzene-d6
benzene-d6
benzene-d6
pyridine
THF
20
23
n.d.
n.d.
complexes
{2-[Ph2P꞊O]C6H4NC(tBu)N(2,6-
iPr2C6H3)}Ln(CH2SiMe3)2 produce predominantly cis-1,4
polyisoprene (up to 98.5 %), which is comparable to the results
obtained for the systems containing bis(alkyl) complexes 2–3
(cis-1,4-units up to 98.4%).
20
20
20
20
20
60
60
20
20
60
60
20
20
20
20
60
78
˃99
<5
22
˃99
84
88
˃99
27
86
91
91
0
3
12
12
12
12
6
0 / >99
—
4
In order to elucidate the catalytically active species forming in
the ternary systems and initiating isoprene polymerization, a
series of NMR-tube reactions was carried out under control of 1H
NMR. It was found that in the reaction of 3 with an equimolar
amount of [Ph3C][B(C6F5)4] in benzene-d6 no elimination of
Ph3CH (δ 5.41 ppm) and 1,3,5-triazapentadiene took place.
However, the appearance of cationic monoalkyl species
[{iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2}Lu(CH2SiMe3)(THF)x][B(C
6F5)4] and Ph3CCH2SiMe3 were detected in the reaction
mixture (see ESI).
5
0 / >99
0 / >99
0 / >99
0 / >99
0 / >99
0 / >99
0 / >99
0 / >99
18 / 82
—
6
toluene
toluene
neat
7
8
6
9
12
12
6
benzene-d6
THF
10
11
12
13
14
15
16
17
The 1H NMR spectrum of the reaction of 3 with [Ph3C][B(C6F5)4]
and 5 equiv. of AliBu3 in benzene-d6 presents a complex set of
signals. Overlapping of the signals of iBu3 and 1,3,5-
triazapentadiene hampers an unambiguous signal assignment.
However, one can state that no transfer of tap ligand from Lu to
Al occurs since the 1H NMR spectrum of the product of the
reaction of AliBu3 with 1,3,5-triazapentadiene presents a set of
signals distinct from that characteristic for 3. The THF molecule
most likely remains coordinated with Lu ion and does not
migrate to Al as it is evidenced by invariability of chemical shifts
of the corresponding signals. Similarly, to the system described
in the paper of Cui[26c] the formation of Ph3CH and isobutene
toluene
neat
6
12
12
12
12
6
benzene-d6
pyridine
THF
<2
87
76
—
toluene
toluene
20 / 80
21 / 79
6
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
27% conversion within 24
h
showing predominant
18
4
6
neat
60
85
26 / 74
regioselectivity (83%) of Markovnikov (2,1) addition product
(entry 4). Complex 3 demonstrated similar activity, only 32%
conversion was reached in 24 h with 73% of Markovnikov (2,1)
regioselectivity (entry 5)[32,33]. Compound 4 was found to be inert
in the case of α-methylstyrene even at 50 °C (24 h). When
cyclohexene was used as a substrate, no hydrosilylation with
PhSiH3 in the presence of 2–4 was observed for all runs (20 °C,
[a]Reactions were carried out on a scale of 1 mmol of PhSiH3 and 1mmol of
styrene, in the presence of 2 mol % catalyst, in 1 mL of solvent. [b]Conversion
was estimated based on integration of the 1H NMR spectrum. [c]The ratio of
1,2- and 2,1-regioisomers was calculated by integration of the resonances in
the 1H NMR spectra, set according to previously published.[30]
In contrast to the platinum group metals, rare-earth catalysts
promote hydrosilylation of alkenes without side reactions, such
as isomerization and dehydrogenative silylation.
48 h, entry 7‒9)[32h]
.
Сomplexes 2–4 were evaluated as pre-catalysts for addition of
PhSiH3 to styrene. The results are summarized in Table 3. The
catalytic reactions in benzene-d6 and toluene were carried out in
the presence of 2 mol % of catalyst at 20 °C and result in 87–
99% conversion in 12 h (Entries 3, 6, 9, 13, 16). Catalytic activity
in coordinating solvent (THF or pyridine) proved to be much
lower and under analogous conditions the reactions in 12 h
achieved 2–27% conversions (Entries 4, 5, 10, 14, 15).
Monitoring the addition of PhSiH3 to styrene under solvent-free
conditions or in toluene solution at 60 °C showed that 84–91%
conversions could be reached in 12 h (see Table 3, Entries 7, 8,
11, 12, 17, 18). Bis(alkyl) complexes 2 and 3 exhibit high
regioselectivity and provide the formation of the Markovnikov
(2,1) addition product PhHC(SiH2Ph)Me[30] in >99% yield (Table
3, Entries 3, 5–12). Complex 4 leads to the formation of a
Table 4. Hydrosilylation of alkenes and alkynes with PhSiH3 catalyzed by
complexes 2–4.[a]
1
2
2
3
4
2
3
4
2
3
4
2
3
4
2
3
4
99
99
87
27
32
0
79 / 21
86 / 14
>99 / 0
17 / 83
27 / 73
—
SiH2Ph
SiH2Ph
n-
C7H15
n-
C7H15
12
24
48
24
48
n-
C7H15
3
4
SiH2Ph
Ph
mixture of products with
a marked predominance of a
5
Ph
Markovnikov addition product (74‒82%, entries 13, 16–18).
Such a regioselectivity in styrene hydrosilylation is normally
rationalized in terms of ηn-coordination between the Lewis
acidic/electrophilic metal center and π-electron system of
styrene, directing the insertion reaction toward the α-phenylalkyl
intermediate.[29b,30]
Ph
iH Ph
2
S
6
7
0
—
SiH2Ph
8
0
—
9
0
—
Complexes 2 and 3 proved to be slightly more active than
mono(alkyl) Sc complex 4 (Table 3, entries 3, 9, 13). It should
also be noted that the scandium compound 4 provided less
regioselective formation of the Markovnikov addition product
(2,1) with a yield of up to 82% compared to compounds 2–3 (>
99%). The related yttrium bis(alkyl) complex [PhC(NC6H3iPr-
2,6)2]Y(CH2SiMe3)2(THF) containing amidinate ligand was
reported to catalyze hydrosilylation of styrene with PhSiH3 (1:1
ratio) in benzene-d6 solution. Quantitative yield was achieved in
SiH2Ph
CH2
10
11
12
13
14
15
[a]
98
95
36
<7
<3
0
88 / 12
94 / 6
83 / 17
n.d.
C5H11
+
n-
C5H11
SiH2Ph
C5H11
SiH2Ph
C5H11
E
Z
SiH2Ph
Ph
CH2
+
Ph
SiH2Ph
n.d.
Ph
Z
SiH2Ph
°C.[31] Complex
[PhC(NC6H3iPr-
Ph
E
190
min
at
80
—
2,6)2]Y(CH2SiMe3)2(THF) provides predominantly the formation
of the Markovnikov (2,1) addition product PhHC(SiH2Ph)Me in
77% yield, while in the presence of compounds 2–3 the reaction
Reaction conditions: substrates:silane (1:1),
2
mol% catalyst, 20 °C,
benzene-d6. [b]Calculated by 1H NMR spectroscopy. [c]The ratio of 1,2- and
2,1-regioisomers was calculated by integration of the resonances in the 1H
NMR spectra or analyzed by GC−MS, set according to previously
published.[10a,28e,30d,32,33]
proceeds in
a more regioselective manner affording the
Markovnikov addition product (2,1) in quantitative yield (> 99%).
In hydrosilylation of 1-nonene with PhSiH3 in benzene-d6
catalyzed by complexes 2–3 quantitative yield is achieved in 12
h at room temperature[32a]. The results are presented in the
Table 4. In the case of complex 2, mainly anti-Markovnikov (1,2)
addition product is formed in 79% yield (entry 1). Lutetium
complex 3 provides the formation of anti-Markovnikov (1,2)
addition product even in higher yield (86%, entry 2), while Sc
complex 4 performed the highest selectivity: in 12 h 87%
conversion was reached with >99% regioselectivity of the
formation of anti-Markovnikov (1,2) addition product (entry 3).
The reactions of 1-heptyne with PhSiH3 in benzene-d6 (24 h,
20 °C) in the presence of 2 mol % of catalyst result in close-to-
complete (98% for 2 and 95% for 3) conversion (Entries 10, 11).
For complex 2, regioselectivity of anti-Markovnikov (1,2) addition
was 88% (entry 10). Lutetium complex 3 provided even higher
selectivity (94%) in anti-Markovnikov (1,2) addition (entry 11).
Complex 4 demonstrated lower activity, only 36% conversion
was reached in 24 h with 83% formation of anti-Markovnikov
(1,2) addition product (entry 12)[32d]
.
Complexes
2 and 3 enable addition of PhSiH3 to 1,1-
Hydrosilylation of phenylacetylene with PhSiH3 catalyzed by
complexes 2–4 has been also investigated. It was found that
complexes 2–3 at room temperature performed low activity: 7%
disubstituted C=C bond of α-methylstyrene, however, the
reactions predictably turned out to be much slower than with
styrene. For complex 2, the catalytic reaction proceeded with
conversion was reached in 48
h .
(Entries 13–14)[32c,32i]
7
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
Compound 4 turned out to be inactive in this transformation.
Thus, one can conclude that complexes 2–4 are more suitable
for catalysis of hydrosilylation of double C=C bonds and are less
active in the case of acetylenes. This is in line with previously
reported observations.[29b,32c] Moreover, it is noteworthy that in
the case of the hydrosilylation reaction of alkenes and alkynes
(Table 4), higher selectivity of the lutetium complex compared to
the yttrium counterpart is observed.
Hydrosilylation of 1,5-hexadiene with PhSiH3 catalyzed by rare-
earth complexes is known to be able to afford a series of
products: 1,6-bis(phenylsilyl)hexane, 6-phenylsilyl-1-hexene,
(phenylsilylmethyl)cyclopentane, phenylsilacycloheptane as well
as oligomers.[33] The possible reaction pathways of 1,5-
hexadiene hydrosilylation by rare-earth metal catalyst has been
formerly proposed.[30e]
It was interesting to compare activity and selectivity of the alkyl
complexes
with
those
of
formerly
reported
compounds.[28b] Dimeric hydrido yttrium complex [Y(L)(THF)(µ-
H)]2 (L = (C5Me4CH2SiMe2NCMe3)2)[35] with a linked amido-
cyclopentadienyl ligand catalyzed hydrosilylation of 1,5-
hexadiene with PhSiH3 (1:1 ratio) in hexane, and quantitative
yield was achieved in 120 min at 25 °C. For the complex
[Y(L)(THF)(µ-H)]2, a mixture of products consisting of both linear
and cyclized products as well as involatile oligomers was formed.
Yttrium
alkyl
complex
[Y(etbmp)(CH2SiMe3)(THF)n][30d]
containing tetradentate [OSSO]-type bis(phenolato) ligand was
reported to catalyze hydrosilylation of 1,5-hexadiene with
PhSiH3 (1:2 ratio, 50 °C, 21 h) yielding predominantly 1,6-
bis(phenylsilyl)hexane
(90%)
and
(phenylsilylmethyl)cyclopentane (10%). Compared with the data
mentioned above, complexes 2–4 proved to be more active pre-
catalysts for hydrosilylation of 1,5-hexadiene with PhSiH3 (1:2
ratio, 20 °C, 1 h), however do not provide sufficient control of
selectivity.
Hydrosilylation of 1,5-hexadiene with PhSiH3 (1:2 ratio) in
benzene-d6 at room temperature catalyzed by complexes 2 and
3 was monitored by 1H NMR spectroscopy[30c,30e] and GC−MS. In
the case of complex 2, the reaction leads to the formation of a
mixture of products: 1,6-bis(phenylsilyl)hexane (84%) and
(phenylsilylmethyl)cyclopentane (16%). Complex 3 also affords
a
mixture
of
1,6-bis(phenylsilyl)hexane
(77%)
and
Conclusion
(phenylsilylmethyl)cyclopentane (23%). Notably, GC–MS also
allowed to determine phenylsilacycloheptane in trace amounts
(<0.1%) (Scheme 4). However, when the reaction of 1,5-
hexadiene with PhSiH3 in the presence of complexes 2 and 3 is
performed at 1:1 ratio, we also observe the formation of
phenylsilacycloheptane. Hydrosilylation of 1,5-hexadiene with
In
summary,
new
bis(alkyl)
complexes
[iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2]Ln(CH2SiMe3)2(THF) (Ln
=Y (2), Lu (3)) coordinated by 1,3,5-triazapentadienyl ligand
were synthesized through alkane elimination reaction. X-ray
analysis established that in complex 3 the triazapentadienyl
ligand coordinates to the Lu3+ ion in rather unusual “amidinate”
PhSiH3 catalyzed by
2
affords
a
mixture of 1,6-
bis(phenylsilyl)hexane (54%), phenylsilacycloheptane (11%) and
(phenylsilylmethyl)cyclopentane (35%). For the complex 3, a
product mixture consisting of 1,6-bis(phenylsilyl)hexane (48%),
fashion resulting in the formation of
metallocycle. Surprisingly, the analogous reaction with
Sc(CH2SiMe3)3(THF)2 resulted in the cleavage of one C−N
a
four-membered
phenylsilacycloheptane
(14%)
and
bond of 1,3,5-triazapentadiene and afforded
a
dimeric
mono(alkyl)
complex
[{μ2-
(phenylsilylmethyl)cyclopentane (38%) is also formed. So, both
compounds 2 and 3 demonstrate similar activity and selectivity
in the hydrosilylation of 1,5-hexadiene with PhSiH3.
iPr2C6H3NC(Ph)N}Sc(CH2SiMe3)(THF)]2 (4) coordinated by μ2-
bridging dianionic amidinate ligand. Complexes 2–4 were
evaluated as components of ternary catalytic systems
SiH2Ph
PhH2Si
Ln/borate/AliBu3
(borate:
[Ph3C][B(C6F5)4]
(TB),
:
:
:
2
3
4
68%
84%, 77%,
Ph
−
2
4
2
mol%
[PhNHMe2][B(C6F5)4] (HNB), [Ln]/[borate]/[AliBu3] = 1/1/10) for
isoprene polymerization. All obtained polymer samples feature
microstructures containing predominantly cis–1,4-units (66.3–
98.4%). The alkyl complexes 2–4 proved to be active in catalysis
of olefin hydrosilylation and demonstrated excellent
regioselective preference for terminal (1,2) addition to aliphatic
olefins and favored internal (2,1) addition in the case of styrene.
In hydrosilylation of 1-nonene with PhSiH3 complexes 2–3
provide quantitative conversion in 12 h at room temperature with
predominant formation of anti-Markovnikov addition product (79–
86%). Complex 4 performed slightly lower activity but higher
selectivity compared to those of 2–3: in 12 h 87% conversion
was reached with >99% regioselectivity in the formation of anti-
Markovnikov (1,2) addition product. Complexes 2–4 were shown
to catalyze efficiently the hydrosilylation of 1,5-hexadiene with
PhSiH3 (1:2 ratio) to give a mixture of products, predominantly
1,6-bis(phenylsilyl)hexane (68–84%). When the reaction of 1,5-
hexadiene with PhSiH3 in the presence of complexes 2–4 is
performed at the 1:1 ratio, we observe a decrease in the amount
of 1,6-bis(phenylsilyl)hexane (41–54%) but the yield of
+
+
2 PhSiH3
Si
H
benzene-d6 20° 1 h
,
C,
SiH2Ph
>
99.9 %
:
2
:
:
4
25%
:
3
traces,
:
4
7%
3
2
,
16%, 23%,
SiH2Ph
PhH2Si
:
2
:
:
4
3
41%
54%, 48%,
Ph
−
2
4
2
mol%
+
+
PhSiH3
Si
H
benzene-d6 20° 1 h
,
C,
SiH2Ph
>
99.9 %
:
:
:
:
:
:
4
20%
11%, 14%,
2
3
4
2
3
39%
35%, 38%,
Scheme 4. Hydrosilylation of 1,5-hexadiene with PhSiH3 catalyzed by alkyl
complexes 2–4.
Hydrosilylation of 1,5-hexadiene with PhSiH3 (1:2 ratio)
catalyzed by 4 affords a mixture of 1,6-bis(phenylsilyl)hexane
(68%),
phenylsilacycloheptane
(7%)
and
(phenylsilylmethyl)cyclopentane (25%). When the reaction of
1,5-hexadiene with PhSiH3 in the presence of complex 4 is
performed at the 1:1 ratio, we observe the formation of 1,6-
bis(phenylsilyl)hexane (41%), phenylsilacycloheptane (20%) and
(phenylsilylmethyl)cyclopentane (39%). The composition of the
reaction products was determined by 1H NMR[30a,34] and GC−MS.
phenylsilacycloheptane
(11–20%)
and
(phenylsilylmethyl)cyclopentane (35–39%) increases.
8
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
THF), 6.71‒7.34 (m, 16 H, Ar–H). 13C NMR (100 MHz, C6D6, 25 °C): δ
4.6 (CH2SiMe3), 23.2 (CH(CH3)2), 25.0 (β-CH2, THF), 25.2 (CH(CH3)2),
28.6 (CH(CH3)2), 46.3 (CH2SiMe3), 70.4 (α-CH2, THF), 122.6, 123.6,
124.5, 128.9, 129.0, 137.1, 140.0, 143.8 (Ar–C); 176.9 (NCN) ppm. IR
(Nujol, KBr) (υ, cm-1): 1600 (s), 1577 (s), 1507 (s), 1312 (s), 1249 (s),
1239 (s), 1180 (w), 1158 (w), 1135 (m), 1095 (s), 1070 (m), 1022 (s), 853
(s), 774 (s), 765 (s), 740 (s), 698 (s), 673 (s). Elemental Anal. Calc. for
C50H74LuN3OSi2 (964.27 g/mol): Calculated (%): C, 62.28; H, 7.74; N,
4.36; Lu, 18.14. Found (%): C, 62.04; H, 7.80; N, 4.17, Lu, 18.02.
Experimental Section
All manipulations were performed in evacuated tubes using standard
Schlenk-flask techniques or under purified nitrogen in a glove-box with
rigorous exclusion of traces of moisture and air. After drying over KOH,
THF was purified by distillation from sodium/benzophenone ketyl; hexane
and toluene were dried by distillation from sodium/benzophenone ketyl
prior to use. Benzene-d6 was dried with sodium and condensed in
vacuum into NMR tubes prior to use. Chloroform-d was used without
additional purification. Ln(CH2SiMe3)3(THF)2
[36]
and 1[15] were prepared
Synthesis of [{μ2-2,6-iPr2C6H3NC(Ph)N}Sc(CH2SiMe3)(THF)]2 (4). A
solution of 1 (0.20 g, 0.37 mmol) in toluene (20 mL) was added to a
solution of (Me3SiCH2)3Sc(THF)2 (0.17 g, 0.37 mmol) in toluene (20 mL)
at 20 °C and the reaction mixture was stirred for 12 h. The toluene
solution was slowly concentrated in vacuum at room temperature.
Complex 4 was isolated as a light-yellow crystalline solid in 43% yield
according to previously published procedures. Ph3SiH was purchased
from Aldrich Chemical Co. Inc. and dried over CaH2 before use.
[Ph3C][B(C6F5)4] and [HNMe2Ph][B(C6F5)4] were purchased from
Synor Ltd. All other commercially available chemicals were used after the
appropriate purifications. NMR spectra were recorded with Bruker
Avance DRX-400 and Bruker DRX-200 spectrometers in chloroform-d
and benzene-d6 at 25 °C, unless otherwise stated. Chemical shifts are
reported in ppm relative to TMS and peaks are referenced to the
chemical shifts of residual solvent resonances (1H and 13C). IR spectra
were recorded as Nujol mulls with a “Bruker-Vertex 70” instrument. The
1
(0.08 g). H NMR (400 MHz, 25 °C, C6D6) δ: 0.35 (s, 18H, CH2SiMe3),
3
0.50 (br s, 2H, CH2SiMe3), 0.55 (br s, 2 H, CH2SiMe3), 0.99 (d, JH-H
=
6.8 Hz, 12 H, CH(CH3)2), 1.24 (m, together 20 H, CH(CH3)2, β-CH2,
3
THF), 3.40 (sept, JH-H = 6.8 Hz, 4 H, CH(CH3)2), 3.92 (m, 8 H, α-CH2,
THF), 6.64‒6.84 (m, 7 H, Ar–H), 7.00 (m, 5 H, Ar–H), 7.35 (d, 3JH-H = 8.2
Hz, 4 H, Ar–H). 13C NMR (100 MHz, 25 °C, C6D6), δ 4.0 (CH2SiMe3),
23.3, 25.2 (CH(CH3)2), 25.9 (β-CH2, THF), 28.5 (CH(CH3)2), 47.0
(CH2SiMe3), 70.2 (α-CH2, THF), 123.6, 124.3, 124.6, 125.2, 127.2,
129.0, 129.2, 130.9, 136.6, 140.0, 142.7 (Ar–C); 175,5 (NCN) ppm. IR
(Nujol, KBr) (υ, cm-1): 1677 (w), 1591 (m), 1549 (s), 1308 (m), 1263 (w),
1247(m), 1230 (s), 1180 (m), 1155 (m), 1116 (s), 1071 (m), 1033 (s), 971
(m), 921 (w), 860 (s), 810 (s), 777 (m), 727 (s), 699 (m), 660 (m), 635 (m),
588 (s). Elemental Anal. Calc. for C54H82N4O2Sc2Si2 (965.34 g/mol):
Calculated (%): C, 67.19; H, 8.56; N, 5.80; Sc, 9.31. Found (%): C,
66.97; H, 8.71; N, 5.68, Sc, 9.22.
C, H,
N elemental analysis are conducted in the microanalytical
laboratory of IMOC. Lanthanide metal analysis was carried out by
complexometric titration.[37] GC-MS data were obtained with a Thermo
Electron Corporation, USA & Polaris Q system. GPC was carried out
using the chromatograph “KnauerSmartline” with PhenogelPhenomenex
Columns 5u (300 × 7.8 mm) 104, 105 and a Security Guard Phenogel
Column with RI and UV detectors (254 nm). The mobile phase used was
THF, and the flow rate was 2 mL min−1. Columns were calibrated with
Phenomenex Medium and High Molecular Weight Polystyrene Standard
Kits with peak Mw from 2700 to 2 570 000 Da. The number average
molecular masses (Mn) and polydispersity index (Mw/Mn) of the polymers
were calculated with reference to
polystyrene standards.
a universal calibration versus
2,6-iPr2C6H3N=C(Ph)CH2SiMe3. 1H NMR (400 MHz, 25 °C, C6D6) δ:
0.24 (s, 9H, CH2SiMe3), 0.95 (d, 3JH-H = 6.8 Hz, 6 H, CH(CH3)2), 1.35 (s,
2 H, CH2SiMe3 overlaps with β-CH2, THF), 1.38 (d, 3JH-H = 6.8 Hz, 6 H,
CH(CH3)2), 3.64 (sept, 3JH-H = 6.8 Hz, 2 H, CH(CH3)2), 6.63‒7.39 (m, 8
H, Ar–H). 13C NMR (100 MHz, 25 °C, C6D6), δ 3.9 (CH2SiMe3), 24.1,
25.3 (CH(CH3)2), 28.4 (CH(CH3)2), 30.2 (CH2SiMe3), 124.1, 127.2,
129.4, 129.7, 131.5, 142.4, 143.3, 145.1 (Ar–C); 184.3 (NC) ppm. MS
(EI): m/z = 351.6 [M+].
Synthesis
of
[2,6-iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2-
2,6]Y(CH2SiMe3)2(THF) (2). A solution of 1 (0.19 g, 0.35 mmol) in
hexane (15 mL) was added to a solution of (Me3SiCH2)3Y(THF)2 (0.18 g,
0.35 mmol) in hexane (15 mL) at 0 °C and the reaction mixture was
stirred for 1 h. The reaction mixture was warmed up to room temperature
and was stirred for additional 30 min. The solution was concentrated in
vacuum and cooled to −20 °C. Complex 2 was isolated as a bright-yellow
1
Reaction
of
[2,6-iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2-
crystalline solid in 58% yield (0.18 g). H NMR (400 MHz, C6D6, 25 °C)
3
2,6]Lu(CH2SiMe3)2(THF) with [Ph3C][B(C6F5)4]. [Ph3C][B(C6F5)4]
(19.2 mg, 20.7 μmol) in 0.3 mL of benzene-d6 was added to a solution of
3 (20 mg, 20.7 μmol) in 0.3 mL of benzene-d6 at 25 °C. 1H NMR (200
δ: −0.20 (s, 4H, CH2SiMe3), 0.36 (s, 18H, CH2SiMe3), 0.98 (d, JH-H
=
6.8 Hz, 12 H, CH(CH3)2), 1.32 (d, 3JH-H = 6.8 Hz, 12 H, CH(CH3)2), 1.43
3
(m, 4 H, β-CH2, THF), 3.45 (sept, JH-H = 6.8 Hz, 4 H, CH(CH3)2), 3.75
3
MHz,
25
°C,
C6D6)
[{2,6-iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2-
(m, 4 H, α-CH2, THF), 6.60 (m, 3 H, Ar–H), 6.67 (t, JH-H = 7.5 Hz, 4 H,
Ar–H), 7.00 (m, 5 H, Ar–H), 7.10 (d, 3JH-H = 7.5 Hz, 4 H, Ar–H). 13C NMR
(100 MHz, 25 °C, C6D6), δ 4.8 (CH2SiMe3), 23.3 (CH(CH3)2), 25.6 (β-
CH2, THF), 25.7 (CH(CH3)2), 37.1 (d, 1JY-C = 38.4 Hz, CH2SiMe3), 68.9
(α-CH2, THF), 123.5, 124.3, 127.5, 128.4, 129.1, 137.8, 140.0, 144.1
(Ar–C); 169,2 (NCN) ppm. IR (Nujol, KBr) (υ, cm-1): 1603 (m), 1580 (m),
1504 (s), 1309 (s), 1250 (s), 1236 (s), 1177 (w), 1157 (w), 1135 (m),
1095 (s), 1073 (m), 1028 (s), 859 (s), 777 (s), 766 (s), 695 (s), 670 (m).
Elemental Anal. Calc. for C50H74YN3OSi2 (878.22 g/mol): Calculated
(%): C, 68.38; H, 8.49; N, 4.78; Y, 10.12. Found (%): C, 68.11; H, 8.64; N,
4.62, Y, 10.03.
2,6}Lu(CH2SiMe3)(THF)][B(C6F5)4]: δ (ppm) −0.18 (s, 2H, CH2SiMe3),
0.31 (s, 9 H, CH2SiMe3), 0.99 (d, 3JH-H = 6.7 Hz, 12 H, CH(CH3)2), 1.38
(d, 3JH-H = 6.7 Hz, 12 H, CH(CH3)2 overlaps with β-CH2, THF), 3.64 (m,
together 8 H, CH(CH3)2, α-CH2, THF), 6.95‒7.07 (m, 16 H, Ar–H
overlaps with Ph3CCH2SiMe3); Ph3CCH2SiMe3: δ (ppm) −0.22 (s, 9 H,
CH2Si(CH3)3), 2.05 (s, 2 H, CH2SiMe3), 6.95‒7.07 (m, 9 H, m-Ph and p-
Ph), 7.31 (d, 3JH-H = 7.1 Hz, 6 H, o-Ph).
General procedure for isoprene polymerization. All polymerization
tests were conducted under
a nitrogen atmosphere. In a typical
procedure, 10 μmol of the selected catalyst precursor (2‒4) was
dissolved in toluene (3 mL) and treated with a solution of the proper
activator {10 μmol; [CPh3][B(C6F5)4] or [HNMe2Ph][B(C6F5)4]} in
toluene (2 mL). 10 equiv. of AliBu3 (0.1 mL, 100 μmol, 1.0 M in toluene)
were added and the reaction mixture was stirred for 2 min; then 1 mL (10
mmol) of isoprene was added via syringe at room temperature. The
reaction mixture was stirred for 0.2‒48 h. Afterwards, polymerization was
stopped by quenching the mixture with an excess of methanol (20 mL)
and dried under vacuum at ambient temperature to a constant weight.
The polymer microstructures were determined by 1H and 13C NMR
spectroscopy in CDCl3 at r.t.[25b,26b,38] GPC of polyisoprenes was
performed in THF at 20 °C. The average molecular weights (Mn) and
Synthesis
of
[2,6-iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2-
2,6]Lu(CH2SiMe3)2(THF) (3). A solution of 1 (0.20 g, 0.37 mmol) in
hexane (15 mL) was added to a solution of (Me3SiCH2)3Lu(THF)2 (0.24
g, 0.37 mmol) in hexane (15 mL) at 0 °C and the reaction mixture was
stirred for 1 h. The reaction mixture was warmed up to room temperature
and was stirred for additional 30 min. The solution was concentrated in
vacuum and cooled to −20 °C. Complex 3 was isolated as a bright-yellow
1
crystalline solid in 62% yield (0.22 g). H NMR (400 MHz, 25 °C, C6D6)
3
δ: −0.29 (s, 4H, CH2SiMe3), 0.37 (s, 18H, CH2SiMe3), 1.01 (d, JH-H
=
5.6 Hz, 12 H, CH(CH3)2), 1.19 (m, 4 H, β-CH2, THF), 1.26 (d, 3JH-H = 5.6
Hz, 12 H, CH(CH3)2), 3.37 (m, 4 H, CH(CH3)2), 3.74 (m, 4 H, α-CH2,
9
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
polydispersity (Mw/Mn) of the polymers were calculated with reference to
a universal calibration against polystyrene standards.
[6]
a) S. Arndt, J. Okuda, Adv. Synth. Catal. 2005, 347, 339–354; b) P. M.
Zeimentz, S. Arndt, B. R. Elvidge, J. Okuda, Chem. Rev. 2006, 106,
2404–2433; c) P. G. Hayes, W. E. Piers, M. Parvez, J. Am. Chem.
Soc. 2003, 125, 5622–5623.
Typical procedure for hydrosilylation. All hydrosilylation tests were
conducted in a glove-box under a nitrogen atmosphere. In a typical
procedure, 2 mol. % (0.005 g, 0.006 mmol,) of the selected catalyst
precursor 2 was placed in an NMR tube and dissolved in C6D6 (1 mL).
To the solution, styrene (0.034 mL, 0.3 mmol) and PhSiH3 (0.037 mL, 0.3
mmol) were added and the tube was vigorously shaken. The reaction
[7]
[8]
a) W. Fegler, A. Venugopal, M. Kramer, J. Okuda, Angew. Chem. Int.
Ed. 2014, 53, 2–15; b) J. Okuda, Coord. Chem. Rev. 2017, 340, 2–9.
a) M. Visseaux, F. Bonnet, Coord. Chem. Rev. 2011, 255, 374–420; b)
M. Ephritikhine, Chem. Rev. 1997, 97, 2193–2242; c) J. Kratsch, M.
Kuzdrowska, M. Schmid, N. Kazeminejad, C. Kaub, P. Oña-Burgos, S.
M. Guillaume, P. W. Roesky, Organometallics 2013, 32, 1230–1238; d)
J. Jenter, N. Meyer, P. W. Roesky, S. K.-H. Thiele, G. Eickerling, W.
Scherer, Chem. Eur. J. 2010, 16, 5472–5480; e) G. G. Skvortsov, M. V.
Yakovenko, P. M. Castro, G. K. Fukin, A. V. Cherkasov, J.-F.
Carpentier, A. A. Trifonov, Eur. J. Inorg. Chem. 2007, 3260–3267.
a) I. V. Basalov, D. M. Lyubov, G. K. Fukin, A. S. Shavyrin, A. A.
Trifonov, Angew. Chem. Int. Ed. 2012, 51, 3444–3447; b) N. Y.
Rad’kova, A. O. Tolpygin, V. Y. Rad’kov, N. M. Khamaletdinova, A. V.
Cherkasov, G. K. Fukin, A. A. Trifonov, DaltonTrans. 2016, 45, 18572–
18584.
1
proceeded at room temperature and was monitored by H and 13C NMR
spectroscopy. The ratio of Markovnikov and anti-Markovnikov
regioisomers was calculated by integration of the appropriate signals in
the 1H NMR spectra. The products of hydrosilylation reactions were
identified on the basis of previously published 1H NMR spectroscopic
data for these compounds PhHC(SiH2Ph)Me[30d,33], n-C9H19SiH2Ph[32a]
,
[9]
33]
Ph(Me)2CSiH2Ph[32g,
phenyl(styryl)silane[32i]
,
(E)-hept-1-en-1-yl(phenyl)silane[32d]
,
(Z)-
1,6-
(phenylsilylmethyl)cyclopentane[30e,33]
,
,
(E)-phenyl(styryl)silane[32c]
,
bis(phenylsilyl)hexane[30e,33]
,
phenylsilacycloheptane[34a]
.
[10] a) D. M. Lyubov, A. M. Bubnov, G. K. Fukin, F. M. Dolgushin, M. Y.
Antipin, O. Pelcé, M. Schappacher, S. M. Guillaume, A. A. Trifonov, Eur.
J. Inorg. Chem. 2008, 12, 2090–2098; b) A. A. Trifonov, D. M. Lyubov,
G. K. Fukin, E. V. Baranov, Y. A. Kurskii, Organometallics 2006, 25,
3935–3942.
X-ray crystallography. The X-ray data for 3 and 4 were collected with
Bruker D8 Quest (3) and Bruker Apex II (4) diffractometers (MoKα
-
radiation, ω-scans technique, λꢀ=ꢀ0.71073ꢀÅ) using APEX2[39] software
packages. The structures were solved by direct methods and were
refined by full-matrix least squares on F2 for all data using SHELX.[40]
XABS2[41] (3) and SADABS[42] (4) and were used to perform absorption
corrections. All non-hydrogen atoms in 3 and 4 were found from Fourier
syntheses of electron density (all non-hydrogen atoms were refined
anisotropically). All hydrogen atoms in 3 and 4 were placed in calculated
positions and were refined in the “riding” model with U(H)iso = 1.2Ueq of
[11] a) R. Kempe, Z. Anorg. Allg. Chem. 2010, 636, 2135–2147; b) D. M.
Lyubov, C. Döring, G. K. Fukin, A. V. Cherkasov, A. S. Shavyrin, R.
Kempe, A. A. Trifonov, Organometallics 2008, 27, 2905–2907; c) R.
Kempe, Eur. J. Inorg. Chem. 2003, 5, 791–803; d) S. Qayyum, G. G.
Skvortsov, G. K. Fukin, A. A. Trifonov, W. P. Kretschmer, C. Doring, R.
Kempe, Eur. J. Inorg. Chem. 2010, 2, 248–257.
[12] a) D. Li, S. Li, D. Cui, X. Zhang, Organometallics 2010, 29, 2186−2193;
b) P. G. Hayes, W. E. Piers, R. McDonald, J. Am. Chem. Soc. 2002,
124, 2132−2133; c) F. A. LeBlanc, A. Berkefeld, W. E. Piers, M. Parvez,
Organometallics 2012, 31, 810–818; d) K. D. Conroy, W. E. Piers, M.
Parvez, Organometallics 2009, 28, 6228–6233; e) A. L. Kenward, J. A.
Ross, W. E. Piers, M. Parvez, Organometallics 2009, 28, 3625–3628; f)
W. Mao, L. Xiang, Y. Chen, Coord. Chem. Rev. 2017, 346, 77–90; g) E.
Lu, Y. Li, Y. Chen, Chem. Commun. 2010, 46, 4469–4471; h) E. Lu, J.
Chu, Y. Chen, M. V. Borzov, G. Li, Chem. Commun. 2011, 47, 743–
745; i) J. Chu, X. Han, C. E. Kefalidis, J. Zhou, L. Maron, X. Leng, Y.
Chen, J. Am. Chem. Soc. 2014, 136, 10894–10897; j) C. Wang, J.
Zhou, X. Zhao, L. Maron, X. Leng, Y. Chen, Chem. Eur. J.2016, 22,
1258–1261.
their parent atoms (U(H)iso
=
1.5Ueq for methyl groups).
Platon/SQUEEZE[43] was used to calculate the contribution of the two
toluene solvent molecules per complex 4 to the final structural model.
The crystallographic data and structures refinement details are given in
Table S1. CCDC– 2070349 (3) and 2039699 (4) contains the
supplementary crystallographic data for this paper. These data are
provided free of charge by The Cambridge Crystallographic Data
Centre: ccdc.cam.ac.uk/structures. The corresponding CIF files are also
available as the Supporting Information.
Acknowledgements
[13] a) M. N. Kopylovich, A. J. L. Pombeiro, Coord. Chem. Rev. 2011, 255,
339–355; b) R.K. Ray, G.B. Kauffman, Metal and Non-Metal Biguanide
Complexes, New Age International, New Delhi, 1999.
This study was financially supported by the Russian Science
Foundation (Project No. 17-73-20262-П). SC XRD study of 3
has been carried out in the framework of the Russian state
assignment using the equipment of the Analytical Center of the
G.A. Razuvaev IOMC RAS.
[14] H. V. R. Dias, J. A. Flores, M. Pellei, B. Morresi, G. G. Lobbia, S. Singh,
Y. Kobayashi, M. Yousufuddinc, C. Santini, DaltonTrans. 2011, 40,
8569–8580.
[15] H. Ley, F. Müller, Ber. Dtsch. Chem. Ges. 1907, 40, 2950–2958.
[16] a) P. V. Gushchin, M. R. Tyan, N. A. Bokach, M. D. Revenco, M.
Haukka, M.-J. Wang, C.-H. Lai, P.-T. Chou, V. Yu. Kukushkin, Inorg.
Chem. 2008, 47, 11487–11500; b) N. Heße, R. Fröhlich, I. Humelnicu,
E.-U. Würthwein, Eur. J. Inorg. Chem. 2005, 11, 2189–2197.
[17] a) A. R. Siedle, R. J. Webb, M. Brostrom, R. A. Newmark, F. E. Behr, V.
G. Young, Organometallics 2004, 23, 2281–2286; b) H. V. R. Dias, S.
Singh, Inorg. Chem. 2004, 43, 7396–7402.
Keywords: Rare Earth metal•1,3,5-
triazapentadiene•Hydrosilylation•Polymerization•Isoprene
[1]
[2]
[3]
R. D. Shannon, ActaCrystallogr. 1976, A32, 751–767.
L. R. Morss, Chem. Rev. 1976, 76, 827–841.
a) A. A. Trifonov, Coord. Chem. Rev. 2010, 254, 1327–1347; b) F. T.
Edelmann, D. M. M. Freckmann, H. Schumann, Chem. Rev. 2002, 102,
1851–1896; c) W. E. Piers, D. J. H. Emslie, Coord. Chem. Rev. 2002,
233–234, 131–155; d) A. A. Trifonov, Rus. Chem. Rev. 2007, 76,
1051–1072.
[18] Y. Luo, X. Wang, J. Chen, C. Luo, Y. Zhang, Y. Yao, Organometallics
2009, 694, 1289–1296.
[19] C. Yao, D. Liu, P. Li, C. Wu, S. Li, B. Liu, D. Cui, Organometallics 2014,
33,684−691.
[20] S. Li, D. Cui, D. Li, Z. Hou, Organometallics 2009, 28, 4814–4822.
[21] S. Bambirra, M. W. Bouwkamp, A. Meetsma, B. Hessen, J. Am. Chem.
Soc. 2004, 126, 9182−9183.
[4]
[5]
a) F. Ortu, D. P. Mills Low in Handbookon the Physics and Chemistry of
Rare Earths, Vol. 55 (Eds.: J.-C. G. Bünzli, V. K. Pecharsky), Elsevier,
Amsterdam, 2019, pp. 1–87; b) G. B. Deacon, M. E. Hossain, P. C.
Junk, M. Salehisaki, Coord. Chem. Rev. 2017, 340, 247–265; c) F. T.
Edelmann, Adv. Organomet. Chem. 2008, 57, 183–352.
[22] J. Chu, Q. Zhou, Y. Li, X. Leng, Y. Chen, Sci. ChinaChem. 2014, 57,
1098–1105.
[23] D. M. Lyubov, V. Yu. Rad’kov, A. V. Cherkasov, G. K. Fukin, A. A.
Trifonov, Russ. Chem. Bull. 2016, 65, 2594−2600.
a) M. Zimmerman, R. Anwander, Chem. Rev. 2010, 110, 6194–6259;
b) A. A. Trifonov, D. M. Lyubov, Coord. Chem. Rev. 2017, 340, 10–61.
10
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
[24] a) A. A. Trifonov Rare-Earth Metal Complexes Supported by Nitrogen-
Containing Ligands in Olefin Polymerizationin Olefin Upgrading
Catalysis by Nitrogen-based Metal Complexes I, Vol. 34 (Eds.: G.
Giambastiani, J. Cámpora), Springer, London, 2011, pp. 119−152; b) M.
Nishiura, Z. Hou, NatureChem. 2010, 2, 257−268; c) L. S. Baugh, J. A.
M. Canich Stereoselective Polymerization with Single-Site Catalysts,
CRC Press, 2008; d) J.Hou, Y. Luo, X. Li, J. Organomet. Chem. 2006,
691, 3114–3121; e) L. Friebe, O. Nuyken, W. Obrecht Advances in
Polymer Science, Vol 204,Springer-Verlag, Berlin, Heidelberg, 2006, pp.
1.
[42] L. Krause, R. Herbst-Irmer, G. M. Sheldrick, D. Stalke, J. Appl.
Crystallogr. 2015, 48, 3–10.
[43] A.L. Spek, ActaCrystallogr., Sect. C2015, 71, 9-18.
[25] a) J. Gromada, J.-F. Carpentier, A.Mortreux, Coord. Chem. Rev. 2004,
248, 397−410; b) W. Gao, D. Cui, J. Am. Chem. Soc. 2008, 130, 4984–
4991; c) Z. Zhang, D. Cui, B. Wang, B. Liu, Y. Yang in Molecular
Catalysis of Rare-Earth Elements, Springer, Berlin, 2010, pp. 49–108.
[26] a) Y. Yang, K. Lv, L. Wang, Y. Wang, D. Cui, Chem. Commun. 2010,
46, 6150–6152; b) L. Zhang, M. Nishiura, M. Yuki, Y. Luo, Z.
Hou, Angew. Chem. Int. Ed. 2008, 47, 2642–2645; c) K. Lv, D.
Cui, Organometallics 2010, 29, 2987–2993.
[27] a) X. Xu, Y. Chen, J. Sun, Chem. Eur. J. 2009, 15, 846–850; b) Y. Luo,
J. Baldamus, Z. Hou, J. Am. Chem. Soc. 2004, 126, 13910–13911.
[28] a) B. Marciniec, H. Maciejewski, C. Pietraszuk, P. Pawluć in
Hydrosilylation: A Comprehensive Review on Recent Advances, Part I
(Ed.: B. Marciniec), Springer, Berlin, 2009, pp. 3–51; b) D. Troegel, J.
Stohrer, Coord. Chem. Rev. 2011, 255, 1440–1459; c) R. Hofmann, M.
Vlatković, F. Wiesbrock, Polymers 2017, 9, 534; d) I. Ojima, Z. Li, J.
Zhu in The Chemistry of Organic Silicon Compounds, Vol. 2 (Eds.: Z.
Rappoport, Y. Apeloig), Wiley, New York, 1998, pp. 1687–1792; e) X.
Du, Z. Huang, ACS Catal, 2017, 7, 1227–1243.
[29] a) G. A Molander, W. H. Retsch, J. Am. Chem. Soc. 1997, 119,
8817−8825; b) G. A. Molander, J. A. C. Romero, Chem. Rev. 2002, 102,
2161−2185.
[30] a) M. Rastatter, A. Zulys, P. W. Roesky, Chem. Commun. 2006, 874–
876; b) D. Robert, A. A. Trifonov, P. Voth, J. Okuda, J. Organomet.
Chem. 2006, 691, 4393–4399; c) J. Li, C. Zhao, J. Liu, H. Huang, F.
Wang, X. Xu, C. Cui, Inorg. Chem. 2016, 55, 9105–9111; d) R. M.
Gauvin, F. Buch, L. Delevoye, S. Harder, Chem. Eur. J. 2009,15, 4382–
4393; e) M. Konkol, M. Kondracka, P. Voth, T. P. Spaniol, J. Okuda,
Organometallics 2008, 27, 3774–3784.
[31] S. Ge, A. Meetsma, B. Hessen, Organometallics 2008, 27, 3131–3135.
[32] a) D. M. Lyubov, A. S. Shavyrin, Yu. A. Kurskii, A. A. Trifonov, Russ.
Chem. Bull. 2010, 59, 1765−1770; b) D. S. Levine, T. D. Tilley, R. A.
Andersen. Chem. Commun. 2017, 53, 11881−11884; c) Y.-B. Zhou, Z.-
K. Liu, X.-Y. Fan, R.-H. Li, G.-L. Zhang, L. Chen, Y.-M. Pan, H.-T. Tang,
J.-H. Zeng, Z.-P. Zhan, Org. Lett. 2018, 20, 7748−7752; d) G. Wu, U.
Chakraborty, A. J. Wangelin, Chem. Commun. 2018, 54, 12322−12325;
e) M.-Y. Hu, J. Lian, W. Sun, T.-Z. Qiao, S.-F. Zhu, J. Am. Chem. Soc.
2019, 141, 4579−4583; f) Z. Zong, Q. Yu, N. Sun, B. Hu, Z. Shen, X.
Hu, L. Jin, Org. Lett. 2019, 21, 5767−5772; g) F. Buch, J. Brettar, S.
Harder, Angew. Chem. Int. Ed. 2006, 45, 2741–2745; h) E. Shirakawa,
D. Ikeda, S. Masui, M. Yoshida, T. Hayashi, J. Am. Chem. Soc.2012,
134, 272–279; i) W. J. Teo, C. Wang, Y. W. Tan, S. Ge, Angew. Chem.,
2017, 129, 4392–4396.
[33] P. F. Fu, L. Brard, Y. Li, T. J. Marks, J. Am. Chem. Soc. 1995, 117,
7157–7168.
[34] a) M. Ohashi, M. Konkol, I. D. Rosal, R. Poteau, L. Maron, J. Okuda, J.
Am. Chem. Soc. 2008, 130, 6920–6921; b) Y. Horino, T. Livinghouse,
Organometallics 2004, 23, 12–14.
[35] A. A. Trifonov, T. P. Spaniol, J. Okuda, DaltonTrans. 2004, 33, 2245–
2250.
[36] a) M. F. Lappert, R. J. Pearce, J. Chem. Soc., Chem. Commun. 1973,
126; b) H. Schumann, D. M. M. Freckmann, S. Dechert, Z. Anorg. Allg.
Chem. 2002, 628, 2422–2426.
[37] S. J. Lyle, M. M. Rahman, Talanta 1963, 10, 1177–1182.
[38]a) A. He, G. Wang, W. Zhao, X. Jiang, W. Yao, W.-H. Sun, Polym. Int.
2013, 62, 1783–1790; b) H. Liu, J. He, Z. Liu, Z.Lin, G. Du, S. Zhang, X.
Li, Macromolecules 2013, 46, 3257–3265.
[39] Bruker (2016). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.
[40] G. M. Sheldrick, ActaCrystallogr., Sect. C2015, 71, 3–8.
[41] S. Parkin, B. Moezzi, H. Hope, J. Appl. Crystallogr., 1995, 28, 53.
11
This article is protected by copyright. All rights reserved.

10.1002/ejic.202100250
European Journal of Inorganic Chemistry
FULL PAPER
Entry for the Table of Contents
ca
.
t
so rene
o
mer za on
I
l
i
ti
p
p
y
Ph
C
Ph
C
r
iP
r
iP
ca
.
t
N
N
N
r
iP
n
y
r
1
e u v.
iP
n
L
0000 i
THF
q
Cis-1
4
selectivit
,
N
Ph
Ph
e
SiM
3
3
u
to 98.4%
p
e
SiM
C
C
N
=
Ln Y Lu
,
r
iP
r
iP
NH
-s
a e
h
d
p
“am na
idi
e
e”
yp
Y
t
t
r
r
iP
iP
+
r
iP
ros
il
a
ti
on
H
d
l
y
y
n
L
e
CH2SiM 3THFx
)
3
THF
e
SiM
(
3
C
N
Sc
PhSiH3
mo ca .
t
N
iPr
N
r
iP
R
SiH2Ph
+
2
l%
R
c
S
N
r
iP
SiH2Ph
THF
R
C
e
SiM
3
ca
.
t
In Y3+and Lu 3+bis(alkyl) complexestriazapentadienyl ligand adopts previously unknownκ2-N,N’“amidinate” coordination mode.The attempt of
synthesis of the Sc3+analogue results in the cleavage of C-N bond of 1,3,5-triazapentadiene and affords a dinuclearmonoalkyl complex
coordinated by dianionicamidinate ligand.Alkyl complexes were testedas catalysts for isoprene polymerization and olefin hydrosilylation.
12
This article is protected by copyright. All rights reserved.