Yttrium hydride complex bearing CpPN/amidinate heteroleptic ligands: Synthesis, structure, and reactivity

Article abstract of DOI:10.1021/om3003703

The reaction of the yttrium dialkyls (C₅H₄-PPh ₂=N-C₆H₃ⁱPr₂)Y(CH ₂SiMe₃)₂(thf) (1) with an excess of N,N′-diisopropylcarbodiimide gave the yttrium monoalkyl complex (C ₅H₄-PPh₂=N-C₆H₃ ⁱPr₂)Y(CH₂SiMe₃)[ ⁱPrN=C(CH₂SiMe₃)-NⁱPr] (2). 2 subsequently reacted with 1 equiv of PhSiH₃ to generate the CpPN/amidinate heteroleptic yttrium hydride {(C₅H₄- PPh₂=N-C₆H₃ⁱPr₂)Y[ ⁱPrN=C(CH₂SiMe₃)-NⁱPr](μ-H)} ₂ (3). Hydride 3 showed good reactivity toward various substrates containing unsaturated C-C, C-N, and N-N bonds, such as azobenzene, p-tolyacetylene, 1,4-bis(trimethylsilyl)-1,3-butanediyne, N,N′- diisopropylcarbodiimide, and 4-dimethylaminopyridine, affording the yttrium hydrazide complex 4 with a rare η²-Cp bonding mode, yttrium terminal alkynyl complex 5, yttrium η³-propargyl complex 6, yttrium amidinate complex 7, and yttrium 2-hydro-4-dimethylaminopyridyl product 8, respectively.

Full text of DOI:10.1021/om3003703

Article
pubs.acs.org/Organometallics
Yttrium Hydride Complex Bearing CpPN/Amidinate Heteroleptic
Ligands: Synthesis, Structure, and Reactivity
Zhongbao Jian,†,‡,# Noa K. Hangaly,∥,# Weifeng Rong,†,‡ Zehuai Mou,†,‡ Dongtao Liu,† Shihui Li,†
Alexander A. Trifonov,⊥ Jorg Sundermeyer,*,∥ and Dongmei Cui*,†,§
̈
†State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences,
Changchun 130022, China
‡Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
§State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences,
Changchun 130022, China
∥Fachbereich Chemie der Philipps-Universitat Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
̈
⊥G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Tropinina 49, GSP-445, 603950 Nizhny
Novgorod, Russia
S
* Supporting Information
ABSTRACT: The reaction of the yttrium dialkyls (C5H4−
i
PPh2N−C6H3 Pr2)Y(CH2SiMe3)2(thf) (1) with an excess of
N,N′-diisopropylcarbodiimide gave the yttrium monoalkyl
complex (C5H4−PPh2N−C6H3 Pr2)Y(CH2SiMe3)[iPrN
i
C(CH2SiMe3)−NiPr] (2). 2 subsequently reacted with 1
equiv of PhSiH3 to generate the CpPN/amidinate heteroleptic
i
yttrium hydride {(C5H4−PPh2N−C6H3 Pr2)Y[iPrNC-
(CH2SiMe3)−NiPr](μ-H)}2 (3). Hydride 3 showed good
reactivity toward various substrates containing unsaturated C−
C, C−N, and N−N bonds, such as azobenzene, p-tolyacetylene, 1,4-bis(trimethylsilyl)-1,3-butanediyne, N,N′-diisopropylcarbo-
diimide, and 4-dimethylaminopyridine, affording the yttrium hydrazide complex 4 with a rare η2-Cp bonding mode, yttrium
terminal alkynyl complex 5, yttrium η3-propargyl complex 6, yttrium amidinate complex 7, and yttrium 2-hydro-4-
dimethylaminopyridyl product 8, respectively.
which make the resulting hydrides generate a rational balance
between the kinetic stability and the high reactivity.
INTRODUCTION
■
Rare-earth-metal alkyl and hydride complexes have witnessed a
spectacular growth in the past three decades due to their
unique reactivity and crucial role in a wide range of
stoichiometric and catalytic processes.1 In particular, rare-
earth-metal hydrides have occupied a special important place in
the area of rare-earth-metal chemistry, because of the variety of
their intriguing structural and chemical properties.1c−e,h,k,l Since
the discovery of the first rare-earth-metal hydride in the early
1980s,2 a large number of monohydrido, dihydrido, polyhy-
drido, and even terminal hydrido rare-earth-metal complexes
have been synthesized and their reactivity has been studied.3−6
It is noteworthy that the ancillary ligands in these hydrides are
almost focused on either cyclopentadienyl (Cp)-type ligands
(Cp derivatives and constrained-geometry-configuration
(CGC) ligands)3,4 or non-Cp-type ligands, such as amidopyr-
idinate, amidinate, benzamidinate, guanidinate, salicylaldimi-
nate, and tris(pyrazolyl)borate ligands.1d,5,6 Examples of
heteroleptic rare-earth-metal hydrides remain limited;3o,7
especially, the Cp/non-Cp-type heteroleptic hydrides are
scarce. Heteroleptic rare-earth-metal hydrides are of much
interest, because their electronic and steric properties can be
readily tuned by changing the framework of mixed ligands,
On the other hand, as one of the Cp-type ligands, the CGC-
type ancillary ligands have been widely used in the rare-earth-
metal hydrides.1i,4 To date, considerable attention has been
paid to these hydrides that bear the dianionic CGC ancillary
ligands, such as silylene-linked cyclopentadienyl-amido ligands
(CpSiN) and silylene-linked cyclopentadienyl-phosphido li-
gands (CpSiP), because such hydrides are electronically more
unsaturated and have sterically more accessible properties and
thus can be expected to show fascinating reactivity. However,
those rare-earth-metal hydrides supported by the monoanionic
CGC ancillary ligands, such as cyclopentadienyl-phosphazene
ligands (CpPN), remain almost unexplored to date, although
such CpPN-type ligands are of particular interest in comparison
with the CpSiN-type and CpSiP-type ligands.8
We recently disclosed the synthesis of a series of CpPN-type
rare-earth-metal dialkyl complexes.9 In this contribution, we
present the reactivity of the yttrium dialkyl complex (C5H4−
i
PPh2N−C6H3 Pr2)Y(CH2SiMe3)2(thf). More remarkably, we
Received: May 2, 2012
Published: June 6, 2012
© 2012 American Chemical Society
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Scheme 1. Synthesis of 2 by the Reaction of 1 with N,N′-Diisopropylcarbodiimide
wish to uncover a CpPN/amidinate heteroleptic yttrium
hydride and its reactions with unsaturated substrates, such as
azobenzene, p-tolyacetylene, 1,4-bis(trimethylsilyl)-1,3-butane-
diyne, N,N′-diisopropylcarbodiimide, and 4-dimethylaminopyr-
idine, to probe the fundamental reactivity of this new Cp/non-
Cp heteroleptic hydride toward unsaturated C−C, C−N, and
N−N bonds.
Å) from the amidinato group in 2 are in the range of 2.304(2)−
2.462(2) Å.10b In addition, we found that 2 could not further
react with an excess of N,N′-diisopropylcarbodiimide.
Synthesis of Heteroleptic Yttrium Hydride Complex 3.
Heteroleptic alkyl complex 2 was attempted to react with 1
equiv of PhSiH3, although it has a relatively weak reactivity.
Delightful to us, the reaction readily took place at room
temperature and gave the desired CpPN/amidinate hetero-
leptic yttrium hydride 3 in a 60% isolated yield as colorless
crystalline solids (Scheme 2). 3 has good solubility in toluene,
but is sparingly soluble in hexane. In addition, when 3 is stored
at room temperature for 1 week, the NMR spectra indicate that
it does not decompose. In the 1H NMR spectrum of 3, a sharp
well-resolved triplet is observed at δ = 5.32 ppm (1JYH = 26.4
Hz), which is assignable to two Y−H hydrogen protons, thus
indicating coupling of each hydrido ligand with two equivalent
89Y nuclei.6k,m,11 The signal of hydrogen protons of 3 is shifted
downfield in comparison with these triplets at δ = 2.02 ppm
(1JYH = 27.0 Hz) in [(Cp)2Y(thf)(μ-H)]2,2 δ = 2.69 ppm (1JYH
= 32.7 Hz) in [(2,4,7-Me3C9H4)2Y(μ-H)]2,11c and δ = 3.09
RESULTS AND DISCUSSION
■
Reactivity of Yttrium Dialkyl Complex 1. The yttrium
dialkyl complex 1 was synthesized as reported recently by us.9
Addition of 1 equiv of N,N′-diisopropylcarbodiimide to a
mixture solution of hexane and toluene of 1 resulted in the
formation of the yttrium monoalkyl complex (C5H4−PPh2
i
N−C6H3 Pr2)Y(CH2SiMe3)[iPrNC(CH2SiMe3)−NiPr] (2)
1
as colorless solids (75%) (Scheme 1). The H NMR spectrum
of 2 shows two broad singlets at δ = −0.26 to −0.11 ppm and δ
= 1.77 ppm arising from the Y−CH2SiMe3 methylene protons
and the newly generated CH2SiMe3 methylene protons,
respectively. Meanwhile, one singlet is also observed at δ =
176.33 ppm in the 13C NMR spectrum, which is assignable to
the carbon proton of the amidinato group (NC−N).10a The
molecular structure of 2 was determined by X-ray diffraction to
be a CpPN/amidinate heteroleptic monomer (Figure 1). The
bond lengths of Y1−N2 (2.367(5) Å) and Y1−N3 (2.315(5)
11d
ppm (1JYH = 32.8 Hz) in [(tBuC5H4)2Y(μ-H)]2 and is close
to the chemical shifts of these Cp complexes
1
[(C5Me4SiMe2NC6H4R)Y(thf)(μ-H)]2 (δ = 5.10 ppm, JYH
=
28.4 Hz),4a [(C5Me4SiMe2NCMe3)Y(thf)(μ-H)]2 (δ = 5.50
ppm, JYH = 28.8 Hz),11b and [(C5Me4CH2SiMe2NCMe3)Y-
1
(thf)(μ-H)]2 (δ = 5.50 ppm, JYH = 26.8 Hz),11a but is
1
remarkably shifted to the high field compared with the chemical
shifts of non-Cp-ligated complexes [N2BFuY(thf)(μ-H)]2 (δ =
7.71 ppm, 1JYH = 27.0 Hz),11f {[(Me3Si)2NC(NiPr)2]2Y(thf)(μ-
H)}2 (δ = 7.95 ppm, JYH = 26.2 Hz),6k and {[PhC-
1
1
(NSiMe3)2]2Y(thf)(μ-H)}2 (δ = 8.28 ppm, JYH = 27.6
Hz).6m Consistent with these, the H and 13C NMR spectra
1
clearly show that 3 is a dimeric molecule with an internal mirror
plane in the solution state. The interesting NMR spectra of 3
inspired us to study its solid-state structure, which was
successfully resolved by X-ray diffraction to be a CpPN/
i
amidinate heteroleptic dimer {(C5H4−PPh2N−C6H3 Pr2)Y-
[iPrNC(CH2SiMe3)−NiPr](μ-H)}2 (Figure 2). The two
CpPN ligands coordinate to the two yttrium centers (Y1 and
Y2) in different η5/κ1 and η5 bonding modes, respectively. The
N4 atom is away from the Y2 center, and the bond length of
Y1−N1 (2.519(5) Å) in 3 is slightly longer than that of Y1−N1
(2.463(5) Å) in 2. The two amidinate ligands are bonded to the
two yttrium centers (Y1 and Y2) in the same η2-N,N′
coordination mode. The bond lengths of Y1−N2 (2.346(5)
Å), Y1−N3 (2.358(5) Å), Y2−N5 (2.324(6) Å), and Y2−N6
(2.336(6) Å) in 3 are also close to those analogous distances in
2. In the tetranuclear Y2H2 core, the Y−H bond distances are
1.71(6), 2.29(6), 2.29(6), and 2.20(6) Å, respectively. The
Y1···Y2 distance (3.631(2) Å) in 3 is slightly shorter than those
in the complexes [(MeC5H4)2Y(thf)(μ-H)]2 (3.664(1) Å),2
[(1,3-Me2C5H3)2Y(thf)(μ-H)]2 (3.68(1) Å),11e {[(Me3Si)2NC-
Figure 1. X-ray structure of 2 (40% probability of thermal ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): Y1−Cpcent 2.504, Y1−C41 2.419(7), Y1−N1 2.463(5),
Y1−N2 2.367(5), Y1−N3 2.315(5); Cpcent−Y1−N1 88.3, N2−Y1−
N3 57.2(2) (CpCent is the centroid of the cyclopentadienyl ring).
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Scheme 2. Synthesis of the CpPN/Amidinate Heteroleptic Yttrium Hydride 3
formed PhNNHPh hydrogen proton. Surprisingly, we un-
1
expectedly observe a singlet at δ = 5.46 ppm in the H NMR
spectrum of 4, which correlates with the signal at δ = 67.83
ppm in the 13C NMR spectrum. This unusual signal may be
assigned to the C5H4 group, although it is significantly shifted
upfield in comparison with these chemical shifts at δ = 7.06−
7.17 ppm in 3. The coordination geometry of 4 could not be
understood on the basis of the above NMR information, but
was confirmed by X-ray diffraction to be [(η2-C5H4)−PPh2
N−C6H3 Pr2]Y[iPrNC(CH2SiMe3)−NiPr](η2-PhNNHPh)
i
(Figure 3). The crystal structure of 4 contains a free PhN
NPh molecule. The CpPN ligand coordinates to the Y3+ ion in
a η2/κ1 mode. The bond length of Y1−C2 (2.703(3) Å) is
unexpectedly shorter than that of Y1−C1 (2.778(3) Å), but
both fall in the range of the Y−C(Cp) bond.3h,14 However, the
bond lengths of Y1···C3 (3.345 Å), Y1···C4 (3.729 Å), and
Y1···C5 (3.424 Å) exceed the normal range, suggesting that the
C3, C4, and C5 atoms are away from the metal center.
Furthermore, these bond distances of C1−C2 (1.433(4) Å),
C2−C3 (1.385(5) Å), C3−C4 (1.401(5) Å), C4−C5
(1.375(5) Å), and C1−C5 (1.414(5) Å) indicate that the
electrons tend to delocalize within the Cp framework.
Therefore, the atoms C1, C2, C3, C4, and C5 form a plane,
and the P1 on the C1 atom almost lies in the plane, but the H2
on the C2 atom deviates from the plane by 0.53 Å. As far as we
are aware, this type of η2 bonding mode of the delocalized Cp
moiety in 4 is extremely rare, which has been found in a
tris(cyclopentadienyl)titanium (η5-C5H5)2Ti(η2-C5H5).15 On
the other hand, the (PhNNHPh)− monoanion is bonded to
the central metal in a η2-N,N′ bidentate mode. The bond length
of Y1−N4 (2.209(3) Å) is remarkably shorter than that of Y1−
N5 (2.417(3) Å), indicating that a hydrogen atom H65 is
located on N5. The N4−N5 bond distance of the hydrazido
ligand, 1.427(4) Å, is slightly shorter than those analogous
distances in (η5-C5Me5)2Sm(PhNNHPh)(thf) (1.443(7) Å)13
and the yttrium hydrazide (1.441(2) Å),7a but remarkably
longer than that of the N−N double bond of PhNNPh
(1.247 Å).16
The interesting structure of 4 encourages us to further study
the reaction of heteroleptic hydride 3 with an unsaturated
substrate containing a C−C triple bond. The reactions of rare-
earth-metal alkyl or hydride complexes with terminal alkynes
are of particular interest, because the resulting alkynyl
complexes adopt various bonding modes ranging from terminal
alkynyls to asymmetric alkynyl and coupled butatrienediyl
bridging ligands in dimeric complexes.6j,l,17,18 Herein, the
hydride 3 reacted with 2 equiv of the terminal alkyne p-
tolyacetylene in hexane and toluene at room temperature to
yield the yttrium alkynyl complex 5 as colorless crystalline
solids (Scheme 3). There is one singlet appearing at δ = 2.10
Figure 2. X-ray structure of the yttrium hydride 3 (40% probability of
thermal ellipsoids). Hydrogen atoms are partly omitted for clarity.
Isopropyl groups on CpPN/amidinate ligands have been also omitted.
Selected bond lengths (Å) and angles (deg): Y1−Cpcent1 2.472, Y2−
Cpcent2 2.442, Y1−N1 2.519(5), Y1−N2 2.346(5), Y1−N3 2.358(5),
Y2−N5 2.324(6), Y2−N6 2.336(6), Y1−H88 1.71(6), Y1−H89
2.29(6), Y2−H88 2.29(6), Y2−H89 2.20(6), Y1···Y2 3.631(2);
Cpcent1−Y1−N1 88.1 (CpCent1 and CpCent2 are the centroids of the
cyclopentadienyl ring).
(Ni P r)2 ]2 Y(thf)(μ-H)}2 (3. 683(5) Å), 6 k and
[(C5Me4CH2SiMe2NCMe3)Y(thf)(μ-H)]2 (3.709(8) Å).11a
Reactivity of Hydride 3 toward Unsaturated Sub-
strates. We first studied the reactivity of heteroleptic hydride 3
with azobenzene containing a NN bond. To date, the
reactions of divalent rare-earth-metal complexes with azoben-
zene have been extensively reported,12 but examples on the
reactions of rare-earth-metal hydrides with azobenzene are
rare.7a,13 Evans and co-workers have reported the reaction of
[(η5-C5Me5)2Sm(μ-H)]2 with azobenzene, affording the
samarium hydrazide (η5-C5Me5)2Sm(PhNNHPh)(thf).13 Very
recently, Chen and co-workers also synthesized a yttrium
hydrazide through the reaction of the yttrium anilido hydride
with azobenzene.7a Herein, the reaction of 3 with 4 equiv of
azobenzene in hexane and toluene at room temperature readily
yielded the yttrium hydrazide 4 as yellow crystalline solids in a
49% isolated yield (Scheme 3). In the 1H NMR spectrum of 4,
the Y−H signal disappears; instead, a slightly broad singlet
appears at δ = 3.58 ppm, which can be attributed to the newly
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Scheme 3. Reactivity of the Hydride 3 toward Unsaturated Substrates
ppm in the 1H NMR spectrum of 5, which can be attributed to
the hydrogen protons from the CCPhMe group. Notably,
67.5 Hz) and 107.44 ppm (2JYC = 13.5 Hz) in the 13C NMR
spectrum, belonging to the α- and β-carbons of the CCPhMe
group, respectively. This is consistent with these chemical shifts
reported in yttrium terminal alkynyl complexes (TptBu,Me)Y-
two doublets are obviously observed at δ = 142.25 ppm (1JYC
=
1
(CCPh)2 (143.77 ppm, d, JYC = 59.3 Hz; and 102.22 ppm,
d, JYC = 12.05 Hz)17 and (C5Me5)2Y(CCPh)(OEt2)
2
1
2
(146.95 ppm, d, JYC = 70.9 Hz; and 109.59 ppm, d, JYC
=
12.05 Hz),18i suggesting that 5 is a terminal alkynyl complex.
To further confirm its structure, single crystals of 5 suitable for
an X-ray structure determination were obtained by recrystal-
lization from hexane and toluene at room temperature. 5 was
clearly established by the X-ray analysis to be (C5H4−PPh2
N−C6H3 Pr2)Y[iPrNC(CH2SiMe3)−NiPr][CCPh(p-
i
Me)] (see the Supporting Information, Figure S1).19
The reaction of hydride 3 with a diyne containing conjugated
triple bonds was further studied. Reports on the reactions of
rare-earth-metal hydrides with diynes are rare.3n,20 Takats and
co-workers have explored the reaction of [(TptBu,Me)Yb(μ-H)]2
with 1,4-bis(trimethylsilyl)-1,3-butanediyne, giving a propargyl
complex.20 Hou and co-workers also introduced the reaction of
[(C5Me4SiMe3)Y(μ-H)2]4(thf) with 1,4-bis(trimethylsilyl)-1,3-
butanediyne, affording a butene-tetraanion complex.3n On the
basis of these pioneer works, the reaction of 3 with 2 equiv of
1,4-bis(trimethylsilyl)-1,3-butanediyne at room temperature
produced the complex 6 as a pale yellow oil (Scheme 3).
The oil was extremely soluble in hexane even at −30 °C, so we
could not isolate the single crystals of 6. Fortunately, we could
confirm its structure from the NMR information. The absence
of the hydride signal at δ = 5.32 ppm indicates the consumption
of hydride 3. In addition to the characteristic CpPN and
amidinate ligands signals, one singlet appearing at δ = 7.14 ppm
Figure 3. X-ray structure of 4 (40% probability of thermal ellipsoids).
Hydrogen atoms are partly omitted for clarity. Selected bond lengths
(Å) and angles (deg): Y1−C1 2.778(3), Y1−C2 2.703(3), Y1···C3
3.345, Y1···C4 3.729, Y1···C5 3.424, Y1−N1 2.417(3), Y1−N2
2.314(3), Y1−N3 2.341(3), Y1−N4 2.209(3), Y1−N5 2.417(3),
C1−C2 1.433(4), C2−C3 1.385(5), C3−C4 1.401(5), C4−C5
1.375(5), C1−C5 1.414(5), N4−N5 1.427(4); N4−Y1−N5 356(1).
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in the 1H NMR spectrum, which correlates with one doublet at
δ = 147.84 ppm (2JYC = 3.0 Hz) in the 13C NMR spectrum, and
two different SiMe3 signals at δ = 0.48 and 0.56 ppm suggest
the formation of an olefinic bond that comes from addition of
Y−H to one of the two triple bonds. Compared to the related
chemical shift reported in the ytterbium propargyl complex (δ
= 7.65 ppm (1H) and δ = 152.5 ppm (13C)),20 this signal at δ =
7.14 ppm can be assigned to one hydrogen proton of the C
CH(SiMe3) group. Of particular note is that the doublet
appearing at δ = 205.28 ppm with the coupling constant of 1JYC
= 46.5 Hz in the 13C NMR spectrum is suggestive of an η3-
propargyl group, which has been observed at δ = 217.1 ppm in
the ytterbium propargyl complex.20
isopropyls on one amidinate framework adopt a cis
conformation, and two isopropyls on another amidinate
framework locate in a trans conformation.
The reactions of rare-earth-metal hydrides with pyridine or
its derivatives, which can form three products, dihydrogen
elimination (I),17i,21 1,2-insertion (II),4a,6j,17j,22 and 1,4-
insertion (III),22,23 have attracted much attention (Chart 1).
Chart 1. Three Products Obtained by the Reaction of Rare-
Earth-Metal Hydride with Pyridine
In the aforementioned text, the Cp/amidinate heteroleptic
monoalkyl complex 2 cannot react with an excess of N,N′-
diisopropylcarbodiimide. In contrast, the reaction of the Cp/
amidinate heteroleptic hydride 3 with 2 equiv of N,N′-
diisopropylcarbodiimide at room temperature readily yielded
the yttrium amidinate complex 7 as colorless crystalline solids
in a 85% high yield (Scheme 3). There is an obvious doublet
Therefore, the reaction of hydride 3 with 4-dimethylaminopyr-
idine (DMAP) was also performed. Hydride 3 reacted with 4
equiv of DMAP to afford the 1,2-insertion product 8 as yellow
crystalline solids (Scheme 3). The X-ray diffraction analysis
revealed its structure as a 2-hydro-4-dimethylaminopyridyl
1
appearing at δ = 8.33 ppm (3JYH = 6.0 Hz) in the H NMR
spectrum of 7, which can be attributed to the NCH−N
hydrogen signal of the amidinate ligand.7a The molecular
structure of 7 was confirmed by X-ray diffraction as (C5H4−
complex (C5 H4 −PPh2 N−C6 H3 Pr2 )Y[i PrNC-
i
(CH2SiMe3)−NiPr][η1-NC5H5(p-NMe2)](DMAP) formed by
1,2-insertion of DMAP into the Y−H bond of 3 (Figure 5).
PPh2N−C6H3 Pr2)Y[iPrNC(CH2SiMe3)−NiPr](iPrN
i
CH−NiPr) (Figure 4). In the solid-state structure of 7, two
Figure 5. X-ray structure of 8 (40% probability of thermal ellipsoids).
Hydrogen atoms are partly omitted for clarity. Selected bond lengths
(Å) and angles (deg): Y1−N2 2.357(5), Y1−N3 2.321(4), Y1−N4
2.222(5), Y1−N6 2.467(5), N4−C41 1.418(8), C41−C42 1.425(9),
N6−C48 1.342(7), N6−C52 1.352(7); N4−C41−C42 116.8(6), N6−
C48−C49 124.5(6), N6−C52−C51 124.4(6).
Figure 4. X-ray structure of 7 (40% probability of thermal ellipsoids).
Hydrogen atoms are partly omitted for clarity. Selected bond lengths
(Å) and angles (deg): Y1−N1 2.594(2), Y1−N2 2.335(2), Y1−N3
2.406(2), Y1−N4 2.396(2), Y1−N5 2.394(2), N2−C30 1.331(3),
N3−C30 1.337(4), N4−C41 1.315(4), N5−C41 1.322(4); N2−Y1−
N3 56.1(8), N4−Y1−N5 56.7(8).
The NMR spectroscopy further confirmed the structure. Five
separate signals assigned to the 2-hydro-4-dimethylaminopyr-
idyl ligand are observed in the 1H NMR spectrum of 8.4a,6j,18j,22
The NMe2 hydrogen protons show one singlet at δ = 2.75 ppm.
A multiplet is found at δ = 4.17−4.18 ppm for the proton in the
3-NC5H5(p-NMe2) position. Two hydrogen protons of the
different amidinate ligands coordinate to the yttrium center in
the same η2-N,N′ bidentate mode with the Y−N bond lengths
of 2.335(2) and 2.406(2)Å, and 2.396(2) and 2.394(2) Å,
respectively, which are obviously shorter than the length of the
coordination Y1−N1 bond (2.594(2) Å). The bond lengths of
N2−C30 (1.331(3) Å) and N3−C30 (1.337(4) Å) are almost
equal, and so are the bond lengths of N4−C41 (1.315(4) Å)
and N5−C41 (1.322(4) Å), indicating that the electrons
delocalize in the amidinate framework. Interestingly, two
methylene group in the 2-NC5H5(p-NMe2) position give rise to
2
a doublet at δ = 4.57 ppm with a coupling constant of JYH
=
36.6 Hz. A doublet of doublets at δ = 5.23 ppm is assigned to
the hydrogen proton in the 5-NC5H5(p-NMe2) position. The
hydrogen proton in the 6-NC5H5(p-NMe2) position is
4583
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Organometallics
Article
observed at δ = 6.06 ppm as a doublet (3JHH = 6.0 Hz).
Notably, the signals from the coordinated DMAP molecule are
also found. In the solid-state structure of 8, the 2-hydro-4-
dimethylaminopyridyl ligand is bonded to the yttrium center in
the η1-N mode. One DMAP molecule coordinates to the
yttrium center, which leads to the leaving of the N1 atom of the
CpPN ligand from the metal center. The length of the Y1−N4
covalent bond (2.222(5) Å) is comparable to the lengths of the
analogous Y−N bonds in Y(η5-C5Me4CH2SiMe2NPh-κN)(η1-
NC5H6)(py)2 (2.294(5) Å)4a and (DADMB)Y(η1-NC5H6)-
(py)2 (2.281(5) Å),22a but is much shorter than the length of
the coordination bond Y1−N6 (2.467(5) Å). The length of the
N4−C41 single bond (1.418(8) Å) is almost equal to that of
the N−C single bond (1.424(8) Å) in (DADMB)Y(η1-
NC5H6)(py)2,22a but is obviously longer than the lengths of
these N6−C48 (1.342(7) Å) and N6−C52 (1.352(7) Å) bonds
in the delocalized DMAP framework. In addition, the N4−
C41−C42 angle of 116.8(6)° in 8 is close to the corresponding
angle (115.2(6)°) in (DADMB)Y(η1-NC5H6)(py)2,22a but is
different from these angles of N6−C48−C49 (124.5(6)°) and
N6−C52−C51 (124.4(6)°) of the DMAP molecule.
0.71073 Å). The determination of crystal class and unit cell parameters
was carried out by the SMART program package.24 The raw frame
data were processed using SAINT and SADABS to yield the reflection
data file.25 The structures were solved by using the SHELXTL
program.26 Refinement was performed on F2 anisotropically for all
non-hydrogen atoms by the full-matrix least-squares method. The
hydrogen atoms were placed at the calculated positions and were
included in the structure calculation without further refinement of the
parameters. The two bridging hydrogen atoms in complex 3 have been
refined anisotropically.
i
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Y-
(CH2SiMe3)[iPrNC(CH2SiMe3)−NiPr] (2). Under a nitrogen
atmosphere, to a mixture solution of hexane and toluene (10 mL)
of 1 (0.380 g, 0.5 mmol) was added 1 equiv of N,N′-
diisopropylcarbodiimide (0.063 g, 0.5 mmol) slowly at room
temperature. The mixture was stirred for 4 h to afford a colorless
solution. Evaporation of the solvent left 2 as colorless crystalline solids
(0.307 g, 75%). Recrystallization from hexane and toluene at −30 °C
1
gave single crystals suitable for X-ray analysis. H NMR (600 MHz,
C6D6, 7.16 ppm, 25 °C): δ −0.26 and −0.11 (overlapped br s, 2H,
YCH2SiMe3), 0.09 (s, 9H, CH2SiMe3), 0.42 (br s, 12H, CH(CH3)2),
0.49 (s, 9H, YCH2SiMe3), 1.34 (s, 12H, CH(CH3)2), 1.77 (br s, 2H,
CH2SiMe3), 3.04 (br s, 1H, CH(CH3)2), 3.35 (br s, 2H, CH(CH3)2),
3.75 (br s, 1H, CH(CH3)2), 6.71−7.05 (m, 13H, Ph-H and Ar-H and
C5H4), 7.46 (br s, 2H, Ph-H), 7.79 ppm (br s, 2H, Ph-H). 13C NMR
(150 MHz, C6D6, 128.06 ppm, 25 °C): δ 0.09 (s, 3C, CH2SiMe3), 4.93
(s, 3C, CH2SiMe3), 16.92 (s, 1C, CH2SiMe3), 23.30−25.75 and
28.80−29.27 (very br m, 8C, CH(CH3)2), 26.53 (br s, 2C,
CONCLUSIONS
■
We have demonstrated the reaction of the yttrium dialkyls with
N,N′-diisopropylcarbodiimide. Strikingly, the CpPN/amidinate
heteroleptic yttrium hydride was synthesized. The NMR and X-
ray diffraction analyses showed that the hydride contains a
tetranuclear Y2H2 core. The reactivity of this new class of
hydride with substrates containing unsaturated C−C, C−N,
and N−N bonds was probed. Reaction of azobenzene with the
hydride afforded the yttrium hydrazide, in which the CpPN
ligand coordinates to the Y3+ ion in a rare η2/κ1 mode.
Protonolysis of the hydride with p-tolyacetylene gave the
yttrium terminal alkynyl complex. The addition of the Y−H
bond of the hydride across one CC bond of 1,4-
bis(trimethylsilyl)-1,3-butanediyne yielded the yttrium η3-
propargyl complex. In addition, the hydride reacted with
N,N′-diisopropylcarbodiimide to generate the yttrium amidi-
nate complex. The 1,2-insertion reaction of the hydride with 4-
dimethylaminopyridine produced the yttrium 2-hydro-4-
dimethylaminopyridyl product.
1
CH(CH3)2), 29.68 (d, JYC = 43.5 Hz, 1C, YCH2SiMe3), 47.95 (br
s, 2C, NCH(CH3)2), 95.77 (d, 1JPC = 124.5 Hz, 1C, ipso-C5H4), 110.03
(br s, 1C, C5H4), 114.65 (br s, 1C, C5H4), 120.83 (br s, 2C, C5H4),
124.14 (d, 5JPC = 4.5 Hz, 1C, Ar-C), 124.46 (d, 4JPC = 3.0 Hz, 2C, Ar-
C), 128.52 (d, 2JPC = 12.0 Hz, 4C, Ph-C), 132.19 (s, 4C, Ph-C), 133.27
(d, 3JPC = 7.5 Hz, 4C, Ph-C), 144.64 (d, 2JPC = 9.0 Hz, 1C, ipso-Ar-C),
3
145.38 (d, JPC = 6.0 Hz, 2C, ipso-Ar-C), 176.33 ppm (s, 1C, NC−
N). Anal. Calcd for C44H67N3PSi2Y (%): C, 64.92; H, 8.30; N, 5.16.
Found: C, 65.32; H, 8.42; N, 5.03.
i
Synthesis of the Hydride {(C5H4−PPh2N−C6H3 Pr2)Y[iPrN
C(CH2SiMe3)−NiPr](μ-H)}2 (3). Under a nitrogen atmosphere, to a
mixture solution of hexane and toluene (10 mL) of 2 (0.407 g, 0.5
mmol) was added 1 equiv of phenylsilane (0.054 g, 0.5 mmol) slowly
at room temperature. The mixture was stirred for 4 h to afford a
colorless solution. Evaporation of the solvent left 3 as colorless
crystalline solids (0.218 g, 60%). Recrystallization from hexane and
1
toluene at −30 °C gave single crystals suitable for X-ray analysis. H
NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.17 (s, 18H,
CH2SiMe3), 1.06 (d, 3JHH = 6.0 Hz, 24H, CH(CH3)2), 1.12 (br s, 12H,
3
EXPERIMENTAL SECTION
CH(CH3)2), 1.34 (d, JHH = 6.0 Hz, 12H, CH(CH3)2), 1.98 (s, 4H,
■
General Procedures and Materials. All manipulations were
performed under a nitrogen atmosphere using standard Schlenk
techniques or an MBraun glovebox. All solvents were purified from the
MBraun SPS system. Samples of yttrium complexes for NMR
spectroscopic measurements were prepared in the glovebox by use
CH2SiMe3), 3.44−3.46 (sept, 4H, CH(CH3)2), 3.70−3.74 (sept, 4H,
1
CH(CH3)2), 5.32 (t, JYH = 26.4 Hz, 2H, YH), 7.06−7.17 (m, 26H,
Ph-H and Ar-H and C5H4), 7.62 ppm (br s, 8H, Ph-H). 13C NMR
(150 MHz, C6D6, 128.06 ppm, 25 °C): δ 0.57 (s, 6C, CH2SiMe3),
17.20 (s, 2C, CH2SiMe3), 24.74 (s, 8C, CH(CH3)2), 25.85 (s, 4C,
CH(CH3)2), 27.41 (s, 4C, CH(CH3)2), 28.81 (s, 4C, CH(CH3)2),
of NMR tubes sealed by paraffin film. H and 13C NMR spectra were
1
1
1
recorded on a Bruker AV600 (FT, 600 MHz for H; 150 MHz for
47.87 (s, 4C, NCH(CH3)2), 106.82 (d, JPC = 132.0 Hz, 2C, ipso-
13C) spectrometer. NMR assignments were confirmed by 1H−1H
C5H4), 116.13 (br s, 4C, C5H4), 117.84 (br s, 4C, C5H4), 121.68 (s,
1
COSY and H−13C HMQC experiments when necessary. Elemental
2C, Ar-C), 124.46 (s, 4C, Ar-C), 128.43 (s, 4C, Ph-C), 131.17 (s, 8C,
3
analysis was performed at the National Analytical Research Centre of
Changchun Institute of Applied Chemistry (CIAC). N,N′-Diisopro-
pylcarbodiimide and phenylsilane were dried over CaH2 under stirring
for 24 h and distilled under reduced pressure before use. Azobenzene,
p-tolyacetylene, 1,4-bis(trimethylsilyl)-1,3-butanediyne, and 4-dime-
thylaminopyridine (DMAP) were purchased from Aldrich and used
without further purification. The yttrium dialkyl complex 1 was
synthesized as reported previously by us.9
X-ray Crystallographic Studies. Crystals for X-ray analysis were
obtained as described in the preparations. The crystals were
manipulated in a glovebox. Data collections were performed at
−88.5 °C on a Bruker SMART APEX diffractometer with a CCD area
detector, using graphite-monochromated Mo Kα radiation (λ =
Ph-C), 133.03 (d, JPC = 9.0 Hz, 8C, Ph-C), 133.60 (br s, 2C, Ph-C),
3
134.17 (br s, 2C, Ph-C), 144.46 (d, JPC = 6.0 Hz, 4C, ipso-Ar-C),
2
145.23 (d, JPC = 6.0 Hz, 2C, ipso-Ar-C), 174.52 ppm (s, 2C, NC−
N). Anal. Calcd for C80H114N6P2Si2Y2 (%): C, 66.01; H, 7.89; N, 5.77.
Found: C, 66.45; H, 8.03; N, 5.62.
i
Synthesis of the Complex [(η2-C5H4)−PPh2N−C6H3 Pr2]Y-
[iPrNC(CH2SiMe3)−NiPr][η2(N,N′)-PhNNHPh] (4). Under a nitro-
gen atmosphere, to a mixture solution of hexane and toluene (5 mL)
of 3 (0.146 g, 0.1 mmol) was added 4 equiv of azobenzene (0.072 g,
0.4 mmol) slowly at room temperature. The mixture was stirred for 12
h to afford a yellow solution. Evaporation of the solvent left 4 as yellow
crystalline solids (0.088 g, 49%). Recrystallization from hexane and
toluene at room temperature gave single crystals suitable for X-ray
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Organometallics
Article
1
analysis. H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ −0.07 (s,
atmosphere, to a mixture solution of hexane and toluene (5 mL) of 3
(0.146 g, 0.1 mmol) was added 2 equiv of N,N′-diisopropylcarbodii-
mide (0.025 g, 0.2 mmol) slowly at room temperature. The mixture
was stirred for 2 h to afford a colorless solution. Evaporation of the
solvent left 7 as colorless crystalline solids (0.145 g, 85%).
Recrystallization from hexane and toluene at room temperature gave
3
9H, CH2SiMe3), 0.72 (d, JHH = 6.0 Hz, 9H, CH(CH3)2), 0.98−1.28
(m, 9H, CH(CH3)2), 1.42 (d, 3JHH = 6.0 Hz, 6H, CH(CH3)2), 1.56 (d,
3JYH = 12.0 Hz, 2H, CH2SiMe3), 3.09 (br s, 1H, CH(CH3)2), 3.29 (br
s, 1H, CH(CH3)2), 3.58 (br s, 1H, PhNNHPh), 3.72 (br s, 2H,
CH(CH3)2), 5.46 (s, 1H, C5H4−Y), 6.37 (br s, 1H, C5H4), 6.76 (t,
3JHH = 3.0 Hz, 2H, C5H4), 6.81−7.62 (m, 19H, Ph-H and Ar-H), 7.62
ppm (br s, 4H, Ph-H). 13C NMR (150 MHz, C6D6, 128.06 ppm, 25
°C): δ −0.04 (s, 3C, CH2SiMe3), 16.84 (s, 1C, CH2SiMe3), 24.23 (br
s, 2C, CH(CH3)2), 24.96 (s, 2C, CH(CH3)2), 25.18 (br s, 2C,
CH(CH3)2), 25.82 (br s, 2C, CH(CH3)2), 27.20 (s, 1C, CH(CH3)2),
29.13 (br s, 1C, CH(CH3)2), 47.75 (s, 2C, NCH(CH3)2), 67.83 (s,
1C, C5H4−Y), 115.16, 117.24, 122.41, 123.36, 124.15, 124.47, 129.25,
129.64, 131.13, 131.89, 131.98, 133.36, 133.72, 145.57, 149.81, 153.28,
155.92 (34C, C5H4 and Ph-C and Ar-C), 175.57 ppm (s, 1C, NC−
N). Anal. Calcd for C52H67N5PSiY (%): C, 68.63; H, 7.42; N, 7.70.
Found: C, 69.14; H, 7.54; N, 7.56.
1
single crystals suitable for X-ray analysis. H NMR (600 MHz, C6D6,
7.16 ppm, 25 °C): δ 0.13 (s, 9H, CH2SiMe3), 0.94 (d, 3JHH = 12.0 Hz,
3
12H, CH(CH3)2), 1.24 (d, JHH = 6.0 Hz, 12H, CH(CH3)2), 1.27 (d,
3JHH = 6.0 Hz, 12H, CH(CH3)2), 1.87 (s, 2H, CH2SiMe3), 3.43−3.52
(m, 4H, CH(CH3)2), 3.71−3.78 (sept, 2H, CH(CH3)2), 6.82−6.84
(quart, 2H, C5H4), 6.98−7.01 (m, 4H, Ph-H), 7.03−7.09 (m, 5H,
C5H4 and Ph-H and Ar-H), 7.13 (d, 3JHH = 6.0 Hz, 2H, Ar-H), 7.56−
3
7.59 (m, 4H, Ph-H), 8.33 ppm (d, JYH = 6.0 Hz, 1H, NCH−N).
13C NMR (150 MHz, C6D6, 128.06 ppm, 25 °C): δ 0.36 (s, 3C,
CH2SiMe3), 17.74 (s, 1C, CH2SiMe3), 24.95 (s, 4C, CH(CH3)2),
25.75 (br s, 4C, CH(CH3)2), 26.07 (s, 4C, CH(CH3)2), 28.37 (br s,
2C, CH(CH3)2), 47.76 (s, 2C, NCH(CH3)2), 52.16 (s, 2C,
i
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Y-
[iPrNC(CH2SiMe3)−NiPr][CCPh(p-Me)] (5). Under a nitrogen
atmosphere, to a mixture solution of hexane and toluene (5 mL) of 3
(0.146 g, 0.1 mmol) was added 2 equiv of p-tolyacetylene (0.023 g, 0.2
mmol) slowly at room temperature. The mixture was stirred for 3 h to
afford a colorless solution. Evaporation of the solvent left 5 as colorless
crystalline solids (0.095 g, 57%). Recrystallization from hexane and
toluene at room temperature gave single crystals suitable for X-ray
analysis. 1H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.13 (s, 9H,
CH2SiMe3), 1.06 (s, 6H, CH(CH3)2), 0.89−1.35 (m, 18H, CH-
(CH3)2), 1.77 (s, 2H, CH2SiMe3), 2.10 (s, 3H, CCPhCH3), 3.02−
3.80 (m, 4H, CH(CH3)2), 6.98−7.16 (m, 16H, Ph-H and Ar-H and
C5H4), 7.58−8.16 ppm (m, 5H, Ar-H and Ph-H). 13C NMR (150
MHz, C6D6, 128.06 ppm, 25 °C): δ −0.09 (s, 3C, CH2SiMe3), 16.41
(s, 1C, CH2SiMe3), 21.35 (s, 1C, CCPhCH3), 24.29 (br s, 4C,
CH(CH3)2), 25.90 (br s, 4C, CH(CH3)2), 29.28 (br s, 2C,
1
NCH(CH3)2), 103.47 (d, JPC = 135.0 Hz, 1C, ipso-C5H4), 116.33
2
3
(d, JPC = 13.5 Hz, 2C, C5H4), 116.75 (d, JPC = 12.0 Hz, 2C, C5H4),
121.98 (d, 5JPC = 3.0 Hz, 1C, Ar-C), 123.94 (d, 4JPC = 1.5 Hz, 2C, Ar-
C), 131.36 (s, 4C, Ph-C), 133.16 (s, 2C, Ph-C), 133.27 (d, JPC = 7.5
Hz, 4C, Ph-C), 133.76 (s, 2C, Ph-C), 144.85 (d, JPC = 6.0 Hz, 2C,
ipso-Ar-C), 145.12 (d, JPC = 7.5 Hz, 1C, ipso-Ar-C), 166.95 (s, 1C,
3
3
2
NCH−N), 174.81 ppm (s, 1C, NC−N). Anal. Calcd for
C47H71N5PSiY (%): C, 66.10; H, 8.38; N, 8.20. Found: C, 66.54; H,
8.50; N, 8.08.
i
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Y-
[iPrNC(CH2SiMe3)−NiPr][η1-NC5H5(p-NMe2)](DMAP) (8).
Under a nitrogen atmosphere, to a mixture solution of hexane and
toluene (5 mL) of 3 (0.146 g, 0.1 mmol) was added 4 equiv of 4-
dimethylaminopyridine (0.050 g, 0.4 mmol) slowly at room
temperature. The mixture was stirred for 2 h to afford a yellow
solution. Evaporation of the solvent left 8 as yellow crystalline solids
(0.112 g, 58%). Recrystallization from hexane and toluene at room
1
CH(CH3)2), 47.99 (s, 2C, NCH(CH3)2), 95.81 (d, JPC = 123.0 Hz,
2
1C, ipso-C5H4), 107.44 (d, JYC = 13.5 Hz, 1C, YCC), 124.13 (d,
2JPC = 3.0 Hz, 2C, C5H4), 124.46 (s, 2C, C5H4), 125.66, 129.12,
131.94, 132.23, 133.59, 135.17 (s, 17C, Ph-C and Ar-C), 128.59 (d,
3JPC = 12.0 Hz, 4C, Ph-C), 142.25 (d, JYC = 67.5 Hz, 1C, YCC),
1
1
temperature gave single crystals suitable for X-ray analysis. H NMR
144.46 (d, 2JPC = 9.0 Hz, 1C, ipso-Ar-C), 145.34 (d, 3JPC = 6.0 Hz, 2C,
ipso-Ar-C), 176.25 ppm (s, 1C, NC−N). Anal. Calcd for
C49H63N3PSiY (%): C, 69.90; H, 7.54; N, 4.99. Found: C, 70.32; H,
7.67; N, 4.87.
(600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.18 (s, 9H, CH2SiMe3), 0.70
(br s, 6H, CH(CH3)2), 1.02 (br s, 12H, CH(CH3)2), 1.35 (br s, 6H,
CH(CH3)2), 1.99 (br s, 6H, NMe2), 2.08 (br s, 2H, CH2SiMe3), 2.75
i
(s, 6H, NMe2), 3.46 (br s, 2H, CH(CH3)2), 3.86 (br s, 2H,
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Y-
[iPrNC(CH2SiMe3)−NiPr][(Me3Si)CHC−CCSiMe3] (6).
Under a nitrogen atmosphere, to a mixture solution of hexane and
toluene (5 mL) of 3 (0.146 g, 0.1 mmol) was added 2 equiv of 1,4-
bis(trimethylsilyl)-1,3-butanediyne (0.039 g, 0.2 mmol) slowly at room
temperature. The mixture was stirred for 3 h to afford a pale yellow
solution. Evaporation of the solvent left 6 as a pale yellow oil (0.155 g,
84%). The oil was extremely soluble in hexane even at −30 °C, so we
2
CH(CH3)2), 4.17−4.18 (m, 1H, 3-NC5H5(p-NMe2)), 4.57 (d, JYH
=
36.6 Hz, 2H, 2-NC5H5(p-NMe2)), 5.23 (dd, 3JHH = 2.4 Hz, 4JHH = 2.4
Hz, 1H, 5-NC5H5(p-NMe2)), 6.06 (d, 3JHH = 6.0 Hz, 3H, 6-NC5H5(p-
NMe2) and 3-, 5-NC5H4(p-NMe2)), 6.58−7.21 (m, 14H, Ph-H and
3
Ar-H and C5H4), 7.47 (d, JHH = 6.6 Hz, 1H, Ar-H), 7.87 (br s, 2H,
Ph-H), 9.13 ppm (br s, 2H, 2-, 6-NC5H4(p-NMe2)). 13C NMR (150
MHz, C6D6, 128.06 ppm, 25 °C): δ 0.17 (s, 3C, CH2SiMe3), 17.69 (s,
1C, CH2SiMe3), 23.62 (s, 2C, CH(CH3)2), 25.18 (s, 4C, CH(CH3)2),
26.34 (s, 2C, CH(CH3)2), 28.52 (s, 2C, CH(CH3)2), 38.04 (s, 2C,
NMe2), 41.36 (s, 2C, NMe2), 47.95 (s, 2C, NCH(CH3)2), 48.73 (s,
1C, 2-NC5H5(p-NMe2)), 79.65 (s, 1C, 3-NC5H5(p-NMe2)), 90.84 (s,
1C, 5-NC5H5(p-NMe2)), 106.76 (s, 2C, 3-, 5-NC5H4(p-NMe2)),
114.64, 116.71, 119.93, 120.27 (br s, 6C, C5H4 and Ar-C), 123.45 (s,
2C, Ar-C), 130.61 (s, 4C, Ph-C), 132.13 (br s, 4C, Ph-C), 132.90 (br s,
4C, Ph-C), 143.83 (s, 2C, ipso-Ar-C), 145.27 (s, 1C, ipso-Ar-C), 147.15
(s, 1C, 6-NC5H5(p-NMe2)), 149.84 (s, 1C, 4-NC5H5(p-NMe2)),
151.24 (s, 2C, 2-, 6-NC5H4(p-NMe2)), 154.59 (s, 1C, 4-NC5H4(p-
NMe2)), 176.89 ppm (s, 1C, NC−N). Anal. Calcd for
C54H77N7PSiY (%): C, 66.71; H, 7.98; N, 10.09. Found: C, 67.04;
H, 8.11; N, 9.95.
1
could not isolate the single crystals. H NMR (600 MHz, C6D6, 7.16
ppm, 25 °C): δ 0.06 (s, 9H, SiMe3), 0.48 (s, 9H, SiMe3), 0.56 (s, 9H,
SiMe3), 1.25−1.33 (m, 12H, CH(CH3)2), 1.71 (s, 2H, CH2SiMe3),
3.44−3.46 (sept, 4H, CH(CH3)2), 3.32 (br s, 4H, CH(CH3)2), 6.77 (s,
2H, C5H4), 7.01−7.16 (m, 11H, Ph-H and Ar-H and C5H4), 7.14 (s,
1H, CCH(SiMe3)), 7.74 ppm (br s, 4H, Ph-H). 13C NMR (150
MHz, C6D6, 128.06 ppm, 25 °C): δ 0.08 (s, 3C, SiMe3), 0.23 (s, 3C,
SiMe3), 1.26 (s, 3C, SiMe3), 16.82 (s, 2C, CH2SiMe3), 24.83 (br s, 4C,
CH(CH3)2), 26.62 (s, 4C, CH(CH3)2), 29.13 (s, 2C, CH(CH3)2),
47.98 (s, 2C, NCH(CH3)2), 95.76 (d, 1JPC = 133.5 Hz, 1C, ipso-C5H4),
116.30 (s, 2C, C5H4), 116.75 (s, 2C, C5H4), 124.12 (s, 1C, Ar-C),
124.48 (s, 2C, Ar-C), 128.54 (s, 4C, Ph-C), 128.62 (s, 4C, Ph-C),
3
132.12 (s, 2C, Ph-C), 133.55 (s, 2C, Ph-C), 144.53 (d, JPC = 9.0 Hz,
3
1C, ipso-Ar-C), 145.45 (d, JPC = 6.0 Hz, 2C, ipso-Ar-C), 147.84 (d,
2JYC = 3.0 Hz, 1C, CCH(SiMe3)), 176.16 (s, 1C, NC−N), 205.28
CCDC-866783 (2), 866784 (3), 866785 (4), 866786 (7), and
866780 (8) 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.
1
ppm (d, 1C, JYC = 46.5 Hz, propargyl-C). Anal. Calcd for
C50H75N3PSi3Y (%): C, 65.11; H, 8.20; N, 4.56. Found: C, 65.54;
H, 8.37; N, 4.45.
i
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Y-
[iPrNC(CH2SiMe3)−NiPr](iPrNCH−NiPr) (7). Under a nitrogen
4585
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Organometallics
Article
(4) (a) Robert, D.; Voth, P.; Spaniol, T. P.; Okuda, J. Eur. J. Inorg.
Chem. 2008, 2810. (b) Hou, Z. Bull. Chem. Soc. Jpn. 2003, 76, 2253
and references cited therein. (c) Okuda, J. Dalton Trans. 2003, 2367.
(d) Tardif, O.; Nishiura, M.; Hou, Z. Tetrahedron 2003, 59, 10525.
(5) Selected reviews: (a) Trifonov, A. A. Coord. Chem. Rev. 2010,
254, 1327. (b) Piers, W. E.; Emslie, D. J. H. Coord. Chem. Rev. 2002,
233−234, 131. (c) Marques, N.; Sella, A.; Takats, J. Chem. Rev. 2002,
102, 2137.
ASSOCIATED CONTENT
* Supporting Information
X-ray crystallographic data for 5 and crystallographic data and
structure refinement details for complexes 2−4, 7, and 8. This
material is available free of charge via the Internet at http://
pubs.acs.org.
■
S
(6) (a) Cheng, J.; Hou, Z. Chem. Commun. 2012, 48, 814.
(b) Venugopal, A.; Fegler, W.; Spaniol, T. P.; Maron, L.; Okuda, J.
J. Am. Chem. Soc. 2011, 133, 17574. (c) Cheng, J.; Shima, T.; Hou, Z.
Angew. Chem., Int. Ed. 2011, 50, 1857. (d) Cheng, J.; Ferguson, M. J.;
Takats, J. J. Am. Chem. Soc. 2010, 132, 2. (e) Skvortsov, G. G.;
Tolpyguin, A. O.; Fukin, G. K.; Cherkasov, A. V.; Trifonov, A. A. Eur.
J. Inorg. Chem. 2010, 1655. (f) Cheng, J.; Saliu, K.; Ferguson, M. J.;
McDonald, R.; Takats, J. J. Organomet. Chem. 2010, 695, 2696.
(g) Schupak, E. A.; Lyubov, D. M.; Baranov, E. V.; Fukin, G. K.;
Suvorova, O. N.; Trifonov, A. A. Organometallics 2010, 29, 6141.
(h) Cheng, J.; Saliu, K. O.; Kiel, G. Y.; Ferguson, M. J.; McDonald, R.;
Takats, J. Angew. Chem., Int. Ed. 2008, 47, 4910. (i) Ohashi, M.;
Konkol, M.; Del Rosal, I.; Poteau, R.; Maron, L.; Okuda, J. J. Am.
Chem. Soc. 2008, 130, 6920. (j) Konkol, M.; Spaniol, T. P.; Kondracka,
M.; Okuda, J. Dalton Trans. 2007, 4095. (k) Trifonov, A. A.;
Skvortsov, G. G.; Lyubov, D. M.; Skorodumova, N. A.; Fukin, G. K.;
Baranov, E. V.; Glushakova, V. N. Chem.Eur. J. 2006, 12, 5320.
(l) Emslie, D. J. H.; Piers, W. E.; Parvez, M.; McDonald, R.
Organometallics 2002, 21, 4226. (m) Duchateau, R.; van Wee, C. T.;
Meetsma, A.; van Duijnen, P. T.; Teuben, J. H. Organometallics 1996,
15, 2279. (n) Hagadorn, J. R.; Arnold, J. Organometallics 1996, 15, 984.
(o) Cheng, J.; Wang, H.; Nishiura, M.; Hou, Z. Chem. Sci. 2012. DOI:
10.1039/C2SC20300F.
AUTHOR INFORMATION
Corresponding Author
*E-mail: dmcui@ciac.jl.cn (D.C.), jsu@staff.uni-marburg.de
(J.S.). Fax: (+86) 431 85262774 (D.C.), +49 (0)6421
2825711 (J.S.). Tel: +86 431 85262773 (D.C.), +49 (0)6421
2825693 (J.S.).
■
Author Contributions
#The authors contributed equally to this work.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was partly supported by The National Natural
Science Foundation of China for project Nos. 20934006,
51073148, and 51021003 and the Ministry of Science and
Technology of China for project No. 2011DFR50650. In
addition, this work was also supported by Deutsche
Forschungsgemeinschaft Priority Program “Lanthanoide spe-
cific functionality” Su 127/8-2. N.K.H. thanks Studienstiftung
des deutschen Volkes for a fellowship.
(7) (a) Lu, E.; Chen, Y.; Leng, X. Organometallics 2011, 30, 5433.
REFERENCES
(b) Lyubov, D. M.; Doring, C.; Ketkov, S. Y.; Kempe, R.; Trifonov, A.
̈
■
A. Chem.Eur. J. 2011, 17, 3824. (c) Lyubov, D. M.; Doring, C.;
̈
(1) Selected reviews: (a) Edelmann, F. T. Coord. Chem. Rev. 2011,
255, 1834. (b) Zimmermann, M.; Anwander, R. Chem. Rev. 2010, 110,
6194. (c) Nishiura, M.; Hou, Z. Nat. Chem. 2010, 2, 257. (d) Konkol,
M.; Okuda, J. Coord. Chem. Rev. 2008, 252, 1577. (e) Hou, Z.;
Nishiura, M.; Shima, T. Eur. J. Inorg. Chem. 2007, 2535. (f) Zeimentz,
P. M.; Arndt, S.; Elvidge, B. R.; Okuda, J. Chem. Rev. 2006, 106, 2404.
(g) Hou, Z.; Wakatsuki, Y. Coord. Chem. Rev. 2002, 231, 1.
(h) Edelmann, F. T.; Freckmann, D. M. M.; Schumann, H. Chem.
Rev. 2002, 102, 1851. (i) Arndt, S.; Okuda, J. Chem. Rev. 2002, 102,
1953. (j) Evans, W. J.; Davis, B. L. Chem. Rev. 2002, 102, 2119.
(k) Ephritikhine, M. Chem. Rev. 1997, 97, 2193. (l) Schaverien, C. J.
Adv. Organomet. Chem. 1994, 36, 283.
Fukin, G. K.; Cherkasov, A. V.; Shavyrin, A. S.; Kempe, R.; Trifonov,
A. A. Organometallics 2008, 27, 2905. (d) Cui, D.; Nishiura, M.; Tardif,
O.; Hou, Z. Organometallics 2008, 27, 2428. (e) Schaverien, C. J.
Organometallics 1994, 13, 69.
(8) CpPN-type ligands have been used in some metal alkyl
complexes. See: (a) Hangaly, N. K.; Petrov, A. R.; Rufanov, K. A.;
Harms, K.; Elfferding, M.; Sundermeyer, J. Organometallics 2011, 30,
4544. (b) Petrov, A. R.; Rufanov, K. A.; Hangaly, N. K.; Elfferding, M.;
Harms, K.; Sundermeyer, J. Mendeleev Commun. 2010, 20, 197.
(c) Petrov, A. R.; Rufanov, K. A.; Ziemer, B.; Neubauer, P.; Kotov, V.
́
V.; Sundermeyer, J. Dalton Trans. 2008, 909. (d) Oulie, P.; Freund, C.;
Saffon, N.; Martin-Vaca, B.; Maron, L.; Bourissou, D. Organometallics
2007, 25, 6793. (e) Freund, C.; Barros, N.; Gronitzka, H.; Martin-
Vaca, B.; Maron, L.; Bourissou, D. Organometallics 2006, 25, 4927.
(f) Rufanov, K. A.; Petrov, A. R.; Kotov, V. V.; Laquai, F.;
Sundermeyer, J. Eur. J. Inorg. Chem. 2005, 3805. (g) Truflandier, L.;
Marsden, C. J.; Freund, C.; Martin-Vaca, B.; Bourissou, D. Eur. J. Inorg.
Chem. 2004, 1939.
(9) Jian, Z.; Petrov, A. R.; Hangaly, N. K.; Li, S.; Rong, W.; Mou, Z.;
Rufanov, K. A.; Harms, K.; Sundermeyer, J.; Cui, D. Organometallics
2012. DOI: 10.1021/om300263p.
(2) Evans, W. J.; Meadows, J. H.; Wayda, A. L.; Hunter, W. E.;
Atwood, J. L. J. Am. Chem. Soc. 1982, 104, 2008.
(3) (a) Shima, T.; Nishiura, M.; Hou, Z. Organometallics 2011, 30,
2513. (b) Nishiura, M.; Baldamus, J.; Shima, T.; Mori, K.; Hou, Z.
Chem.Eur. J. 2011, 17, 5033. (c) Schmiege, B. M.; Ziller, J. W.;
Evans, W. J. Inorg. Chem. 2010, 49, 10506. (d) Takenaka, Y.; Hou, Z.
Organometallics 2009, 28, 5196. (e) Perrin, L.; Maron, L.; Eisenstein,
O.; Tilley, T. D. Organometallics 2009, 28, 3767. (f) Shima, T.; Hou, Z.
Organometallics 2009, 28, 2244. (g) Yousufuddin, M.; Gutmann, M. J.;
Baldamus, J.; Tardif, O.; Hou, Z.; Mason, S. A.; Mclntyre, G. J.; Bau, R.
J. Am. Chem. Soc. 2008, 130, 3888. (h) Evans, W. J.; Schmiege, B. M.;
Lorenz, S. E.; Miller, K. A.; Champagne, T. M.; Ziller, J. W.;
DiPasquale, A. G.; Rheingold, A. L. J. Am. Chem. Soc. 2008, 130, 8555.
(i) Luo, Y.; Hou, Z. Organometallics 2007, 26, 2941. (j) Shima, T.;
Hou, Z. J. Am. Chem. Soc. 2006, 128, 8124. (k) Li, X.; Baldamus, J.;
Nishiura, M.; Tardif, O.; Hou, Z. Angew. Chem., Int. Ed. 2006, 45,
8184. (l) Luo, Y.; Baldamus, J.; Tardif, O.; Hou, Z. Organometallics
2005, 24, 4362. (m) Evans, W. J.; Perotti, J. M.; Ziller, J. W. Inorg.
Chem. 2005, 44, 5820. (n) Cui, D.; Tardif, O.; Hou, Z. J. Am. Chem.
Soc. 2004, 126, 1312. (o) Tardif, O.; Nishiura, M.; Hou, Z.
Organometallics 2003, 22, 1171. (p) Klimpel, M. G.; Sirsch, P.;
Scherer, W.; Anwander, R. Angew. Chem., Int. Ed. 2003, 42, 574.
(q) Hou, Z.; Zhang, Y.; Tardif, O.; Wakatsuki, Y. J. Am. Chem. Soc.
2001, 123, 9216.
(10) (a) Sun, J.; Berg, D. J.; Twamley, B. Organometallics 2008, 27,
683. (b) Zhang, W.; Nishiura, M.; Hou, Z. Chem.Eur. J. 2007, 13,
4037.
(11) (a) Trifonov, A. A.; Spaniol, T. P.; Okuda, J. Organometallics
2001, 20, 4869. (b) Hultzsch, K. C.; Voth, P.; Beckerle, K.; Spaniol, T.
P.; Okuda, J. Organometallics 2000, 19, 228. (c) Kretschmer, W. P.;
Troyanov, S. I.; Meetsma, A.; Hessen, B.; Teuben, J. H. Organo-
metallics 1998, 17, 284. (d) Voskoboynikov, A. Z.; Parshina, I. N.;
Shestakova, A. K.; Butin, K. P.; Beletskaya, I. P.; Kuz’mina, L. G.;
Howard, J. A. K. Organometallics 1997, 16, 4041. (e) Evans, W. J.;
Drummond, D. K.; Hanusa, T. P.; Doedens, R. J. Organometallics
1987, 6, 2279. (f) Luconi, L.; Lyubov, D. M.; Bianchini, C.; Rossin, A.;
Faggi, C.; Fukin, G. K.; Cherkasov, A. V.; Shavyrin, A. S.; Trifonov, A.
A.; Giambastiani, G. Eur. J. Inorg. Chem. 2010, 608.
4586
dx.doi.org/10.1021/om3003703 | Organometallics 2012, 31, 4579−4587

Organometallics
Article
(12) (a) MacDonald, M. R.; Ziller, J. W.; Evans, W. J. Inorg. Chem.
2011, 50, 4092. (b) Pan, C.; Chen, W.; Su, S.; Pan, Y.; Wang, J. Dalton
Trans. 2011, 40, 7941. (c) Evans, W. J.; Champagne, T. M.; Ziller, J.
W. Organometallics 2007, 26, 1204. (d) Evans, W. J.; Miller, K. A.; Lee,
D. S.; Ziller, J. W. Inorg. Chem. 2005, 44, 4326. (e) Hou, Z.; Koizumi,
T.; Nishiura, M.; Wakatsuki, Y. Organometallics 2001, 20, 3323.
(f) Evans, W. J.; Forrestal, K. J.; Ziller, J. W. J. Am. Chem. Soc. 1998,
120, 9273. (g) Trifonov, A. A.; Bochkarev, M. N.; Schumann, H.;
Loebel, J. Angew. Chem., Int. Ed. 1991, 30, 1149. (h) Evans, W. J.;
Drummond, D. K.; Chamberlain, L. R.; Doedens, R. J.; Bott, S. G.;
Zhang, H.; Atwood, J. L. J. Am. Chem. Soc. 1988, 110, 4983.
(13) Evans, W. J.; Kociok-Kohn, G.; Leong, V. S.; Ziller, J. W. Inorg.
̈
Chem. 1992, 31, 3592.
(14) (a) Jian, Z.; Cui, D.; Hou, Z. Chem.Eur. J. 2012, 18, 2674.
(b) Jian, Z.; Cui, D. Chem.Eur. J. 2011, 17, 14578.
(15) Forder, R. A.; Prout, K. Acta Crystallogr., Sect. B 1974, 30, 491.
(16) Brown, C. J. Acta Crystallogr. 1966, 21, 146.
(17) Review on the rare-earth-metal alkynyl complexes: Saliu, K. O.;
Cheng, J.; McDonald, R.; Ferguson, M. J.; Takats, J. Organometallics
2010, 29, 4950.
(18) Selected rare-earth-metal terminal alkynyl complexes; please
see: (a) Ge, S.; Meetsma, A.; Hessen, B. Organometallics 2009, 28,
719. (b) Cameron, T. M.; Gordon, J. C.; Scott, B. L. Organometallics
2004, 23, 2995 and references cited therein. (c) Lin, G.; McDonald,
R.; Takats, J. Organometallics 2000, 19, 1814. (d) Duchateau, R.;
Brussee, E. A. C.; Meetsma, A.; Teuben, J. H. Organometallics 1997,
16, 5506. (e) Lee, L.; Berg, D. J.; Bushnell, G. W. Organometallics
1995, 14, 5021. (f) Evans, W. J.; Keyer, R. A.; Ziller, J. W.
Organometallics 1993, 12, 2618. (g) Heeres, H. J.; Teuben, J. H.
Organometallics 1991, 10, 1980. (h) Evans, W. J.; Ulibarri, T. A.;
Chamberlain, L. R.; Ziller, J. W.; Alvarez, D., Jr. Organometallics 1990,
9, 2124. (i) den Haan, K. H.; Wielstra, Y.; Teuben, J. H.
Organometallics 1987, 6, 2053. (j) Duchateau, R.; van Wee, C. T.;
Teuben, J. H. Organometallics 1996, 15, 2291.
(19) In the X-ray data of 5, the PhMe part of the CCPhMe group
is seriously distorted. We tried our best to determine the single crystal
three times, but the problem was still not solved. Therefore, we did not
discuss the X-ray data in the text. See the Supporting Information.
(20) Ferrence, G. M.; McDonald, R.; Takats, J. Angew. Chem., Int. Ed.
1999, 38, 2233.
(21) (a) Deelman, B.-J.; Stevels, W. M.; Teuben, J. H.; Lakin, M. T.;
Spek, A. L. Organometallics 1994, 13, 3881. (b) Thompson, M. E.;
Baxter, S. M.; Bulls, A. R.; Burger, B. J.; Nolan, M. C.; Santarsiero, B.
D.; Schaefer, W. P.; Bercaw, J. E. J. Am. Chem. Soc. 1987, 109, 203.
(c) Watson, P. L. J. Chem. Soc., Chem. Commun. 1983, 276.
(22) (a) Gountchev, T. I.; Tilley, T. D. Organometallics 1999, 18,
2896. (b) Evans, W. J.; Meadows, J. H.; Hunter, W. E.; Atwood, J. L. J.
Am. Chem. Soc. 1984, 106, 1291.
(23) Kirillov, E.; Lehmann, C. W.; Razavi, A.; Carpentier, J.-F. Eur. J.
Inorg. Chem. 2004, 943.
(24) SMART, Version 5.054; Bruker AXS Inc.: Madison, WI, 2000.
(25) SAINT and SADABS, Version 6.22; Bruker AXS Inc.: Madison,
WI, 2000.
(26) Sheldrick, G. M. SHELXTL NT, Version 6.12; Bruker AXS Inc.:
Madison, WI, 2000.
4587
dx.doi.org/10.1021/om3003703 | Organometallics 2012, 31, 4579−4587