Reactions of bis(alkyl)yttrium complexes supported by bulky N,N ligands with 2,6-diisopropylaniline and phenylacetylene

Article abstract of DOI:10.1021/om300377h

The reactions of bis(trimethylsilylmethyl)yttrium complexes supported by bulky amidopyridinate (Ap) and amidinate (Amd) ligands (LY(CH ₂SiMe₃)₂(THF)_n: L = Ap, n = 1 (1); L = Amd, n = 1 (2)) with 2,6-diisopropylaniline and phenylacetylene were performed. The reaction of 1 with an equimolar amount of 2,6-diisopropylaniline occurs with TMS elimination and affords an yttrium alkyl anilido species which was isolated as a DME adduct, ApY(CH₂SiMe₃)(NH-2,6- ⁱPr₂C₆H₃)(DME) (3). The protonolysis of 3 with phenylacetylene results in the alkynyl anilido derivative ApY(C≡CPh)(NH-2,6-ⁱPr₂C₆H ₃)(DME) (6). The treatment of complexes 3 and 6 with 2,2′-bipy leads to the formation of the bis(anilido) derivative ApY(NH-2,6-iPr ₂C₆H₃)₂(bipy) (5). The formation of a dimeric complex containing two ApY fragments linked by two μ₂-alkynyl groups and a μ-η²:η²- butatrienediyl fragment, [{AmdY(μ₂-C≡CPh)} ₂(μ₂-η²:η²-PhCCCCPh)] (7), was observed in the reaction of 2 with 2 equiv of phenylacetylene.

Full text of DOI:10.1021/om300377h

Article
pubs.acs.org/Organometallics
Reactions of Bis(alkyl)yttrium Complexes Supported by Bulky N,N
Ligands with 2,6-Diisopropylaniline and Phenylacetylene
Alexander V. Karpov, Andrei S. Shavyrin, Anton V. Cherkasov, Georgy K. Fukin,
and Alexander A. Trifonov*
G.A. Razuvaev Institute of Organometallic Chemistry of the Russian Academy of Sciences, Tropinina 49, GSP-445, 603950 Nizhny
Novgorod, Russia
S
* Supporting Information
ABSTRACT: The reactions of bis(trimethylsilylmethyl)yttrium
complexes supported by bulky amidopyridinate (Ap) and
amidinate (Amd) ligands (LY(CH2SiMe3)2(THF)n: L = Ap, n =
1 (1); L = Amd, n = 1 (2)) with 2,6-diisopropylaniline and
phenylacetylene were performed. The reaction of 1 with an
equimolar amount of 2,6-diisopropylaniline occurs with TMS
elimination and affords an yttrium alkyl anilido species which was
isolated as a DME adduct, ApY(CH2SiMe3)(NH-2,6-iPr2C6H3)-
(DME) (3). The protonolysis of 3 with phenylacetylene results in
the alkynyl anilido derivative ApY(CCPh)(NH-2,6-iPr2C6H3)-
(DME) (6). The treatment of complexes 3 and 6 with 2,2′-bipy leads to the formation of the bis(anilido) derivative ApY(NH-
2,6-iPr2C6H3)2(bipy) (5). The formation of a dimeric complex containing two ApY fragments linked by two μ2-alkynyl groups
and a μ-η2:η2-butatrienediyl fragment, [{AmdY(μ2-CCPh)}2(μ2-η2:η2-PhCCCCPh)] (7), was observed in the reaction of 2
with 2 equiv of phenylacetylene.
complexes is C−H bond activation.9d Supposedly these
INTRODUCTION
■
synthetic limitations can be overcome by using bulky
Hydrocarbyl derivatives of rare-earth metals continue to attract
polydentate ligand systems able to provide kinetic stability.
considerable attention as highly active species that exhibit
Bulky amidopyridinate6h,i,12 and amidinate13 ligands which
unique reactivity1 and high potential in the activation and
were shown to allow for the synthesis and isolation of rather
derivatization of unsaturated2 and saturated3 substrates. Due to
stable alkyl rare-earth complexes might provide a suitable
the electrophilic nature of the metal center, rare-earth alkyl
coordination environment for stabilization of the related imido
complexes engage in σ-bond metathesis reactions.4 Bis(alkyl)
species.
rare-earth complexes have been the focus of special interest as
Alkynyl rare-earth complexes are intriguing objects for
potential precursors to cationic mono(alkyl) species that were
investigating the variety of coordination modes of alkynyl
found to be efficient catalysts of homo- and copolymerization
ligands and the factors that drive their coupling in the metal
of olefins and dienes.5 Moreover, they were successfully
atom coordination sphere. The chemistry of metallocene type
employed for the synthesis of polyhydrido rare-earth clusters.6
mono(alkynyl) rare-earth complexes has been explored in
Another possible field of application of bis(alkyl) complexes is
the preparation of rare-earth imido and alkynyl species.
Complexes with multiple nitrogen−metal bonds are of
significant interest, owing to the ability of the MN
detail,14 while little is still known about bis(alkynyl) species.15
Herein we report on the attempted synthesis of terminal
imido species via the reactions of bis(alkyl) yttrium complexes
supported by bulky amidopyridinate and amidinate ligands with
functionality to undergo various reactions (metathesis of
2,6-diisopropylaniline. The reactions of bis(alkyl) yttrium
imines, aldehydes, and carbodiimides, metallacycle formation
complexes with phenylacetylene and the characterization of
the obtained alkynyl derivatives will be considered.
with alkynes and alkenes, and C−H bond activation).7
Surprisingly, unlike the well-developed imido chemistry of the
metals of groups 4−6,8 that of rare-earth metals until recently
RESULTS AND DISCUSSION
remained virtually unexplored.9 The synthesis and character-
■
In continuation of our ongoing work on the synthesis and
ization of the sole example of a scandium complex with a
terminal imido ligand was documented by Chen in 2010.10
reactivity investigation of bis(alkyl) rare-earth complexes we
focused on the reactions of bis(trimethylsilylmethyl)yttrium
Obviously the difficulty of synthesis of terminal imido rare-
earth complexes is related to the strongly pronounced tendency
complexes supported by bulky amidopyridinate (Ap)12 and
of these large metal ions to assemble more stable bi- or
polymetallic complexes with μ2-imido ligands.9,11 Another
possible path of transformation of terminal imido rare-earth
Received: May 5, 2012
Published: July 24, 2012
© 2012 American Chemical Society
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Scheme 1
Scheme 2
amidinate (Amd) ligands (LY(CH2SiMe3)2(THF)n: L = Ap, n
= 1 (1); L = Amd, n = 1 (2)) with reagents containing acidic
N−H or C−H bonds.
result from ligand redistribution, which is further corroborated
by the absence of the putative co-redistribution product 1 in
1
the H NMR spectrum.
Recently Chen and co-workers reported10 that the reaction
of a dimethyl scandium complex coordinated by a tridentate
amino-substituted nacnac ligand with 2,6-diisopropylaniline
afforded a related terminal imido species. In order to prepare
new imido yttrium derivatives, we attempted the reactions of 1
and 2 with 2,6-diisopropylaniline.
Clear pale yellow crystals of 3 suitable for X-ray analysis were
obtained by slow concentration of a DME solution at −20 °C.
Complex 3 crystallizes in the orthorhombic space group Pbca
with eight molecules in the unit cell (one crystallographically
independent molecule in the asymmetric unit). The molecular
structure of complex 3 is shown in Figure 1, and the structure
refinement data are given in Table 1. The X-ray study revealed
that 3 is monomeric in the crystalline state. The yttrium atom is
coordinated by two nitrogen atoms of the chelating
amidopyridinate ligand, one nitrogen of the anilido fragment,
one carbon atom of the alkyl group, and two oxygens of the
DME molecule, thus resulting in a coordination number of 6.
The coordination polyhedron around the yttrium atom adopts
a distorted-octahedral geometry.
The Y−C bond length in 3 (2.421(4) Å) is very close to the
values previously reported for six-coordinated alkyl yttrium
complexes.18 The distances between Y and the nitrogen atoms
of amidopyridinate ligand in 3 are nonequivalent: the distance
to the amido nitrogen (2.317(3) Å) is noticeably shorter than
that to the pyridinato nitrogen (2.504(3) Å). The average Y−N
bond length in 3 is similar to those observed in amidopyr-
idinate yttrium complexes.17a The distance between Y and the
nitrogen atom of the anilido fragment (2.250(3) Å) is
significantly shorter than the Y−N distances of the amidopyr-
idinate ligand and is similar to those observed in related
compounds.19b
The NMR-tube reaction of 1 with an equimolar amount of
2,6-diisopropylaniline gave evidence for the loss of one alkyl
group and concomitant formation of 1 equiv of TMS and an
alkylamido species (Scheme 1).
Similarly to the scandium compound10 the preparative-scale
reaction afforded a pale yellow solution. All our attempts to
isolate the reaction product in a crystalline state failed.
Evaporation of the volatiles under vacuum afforded an off-
white viscous oil. However, subsequent recrystallization of the
oily residue from DME at −20 °C allowed the isolation of a
new alkyl amido yttrium complex coordinated by an Ap ligand
as a DME adduct (3).16 Pale yellow crystals of 3 were obtained
in 72% yield. 3 is soluble in THF and benzene and sparingly
soluble in hexane. The NMR spectra of 3 clearly prove the
2
presence of both alkyl (1H, −0.42 ppm, d, JYH = 36.5 Hz,
1
YCH2; 13C, 31.69 ppm, d, JY,C = 43.4 Hz) and anilido (1H,
4.68 ppm, NH) fragments attached to the yttrium atom. The
evolution of complex 3 in benzene solution was monitored by
1H and 13C NMR spectroscopy. Complex 3 slowly decomposes
in C6D6 solution at 20 °C (∼15% per day) with TMS
i
The reaction of complex 2 with 1 equiv of 2,6-diisopropylani-
line under similar conditions afforded a deep violet solution.
Unfortunately, all our attempts to isolate the reaction products
in an individual state were unsuccessful.
elimination. No activation of C−H bonds of the Me or Pr
groups of the Ap ligand17 was detected, but at the same time a
broad singlet appeared in the region characteristic for anilido
NH protons (4.53 ppm). In 1 week the 1H NMR spectrum of 3
did not contain the signal of the alkyl CH2 protons attached to
yttrium. In order to assign the signal at 4.53 ppm, an NMR-
scale reaction of 3 with 1 equiv of 2,6-diisopropylaniline was
carried out (Scheme 2). This experiment unambiguously
proved that the signal at 4.53 ppm corresponds to the NH
protons of bis(anilido) complex 4. Thereafter, complex 3 slowly
decomposes in solution at 20 °C with formation of TMS and
the bis(anilido) species 4. Hence, complex 4 does not simply
Chen emphasized the crucial role of Lewis base coordination
to the metal center in alkylanilido species for the formation of a
terminal imido scandium complex.10 According to the
procedure described in the publication,10 complex 3 was
treated with an equimolar amount of 4-dimethylaminopyridine.
At 20 °C no reaction occurred. After heating at 60 °C for 2
1
days, the reaction mixture turned deep brown and H NMR
spectroscopy detected release of 1 equiv of TMS. Unfortu-
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nately, all attempts of isolation of the product in an individual
state failed. Complex 3 was reacted with an equimolar amount
of 2,2′-bipy in toluene at 20 °C (Scheme 3). The reaction
Scheme 3
mixture immediately became brownish violet. Slow concen-
tration of the reaction mixture at ambient temperature allowed
for the isolation of deep red crystals of an amidopyridinate
bis(anilido) yttrium complex coordinated by 2,2′-bipy, 5.
Complex 5 was obtained in 45% yield. In order to elucidate
the path of formation of 5, the NMR-scale reaction of 3 with
1
2,2′-bipy was carried out in C6D6 and monitored by H NMR.
1
The H NMR spectrum of the reaction mixture indicated a
rapid substitution of DME by 2,2′-bipy in the coordination
sphere of the metal. The signal at −0.42 ppm related to the
YCH2 protons of the parent complex 3 disappeared; however,
no elimination of TMS was observed. The appearance of a new
high-field-shifted singlet at −0.09 ppm of an integral intensity
corresponding to two protons gave evidence for the formation
of new alkyl species in the reaction mixture. Thus, a ligand
redistribution reaction seems to be a plausible explanation for
the formation of complex 5. Attempts to isolate ApY-
(CH2SiMe3)2(bipy), the expected second product of this
reaction, failed. A gradual decay of the signal at −0.09 ppm
implies further transformation of this compound.
Figure 1. Crystal structure of [ApY(CH2SiMe3)(NHAr)(DME)2] (3).
Thermal ellipsoids are drawn at the 30% probability level. Hydrogen
atoms (except those of CH2 and NH fragments) are omitted for
clarity. Selected bond lengths (Å) and angles (deg): Y(1)−N(3) =
2.250(3), Y(1)−N(1) = 2.317(3), Y(1)−O(1) = 2.409(3), Y(1)−
C(30) = 2.421(4), Y(1)−O(2) = 2.459(3), Y(1)−N(2) = 2.504(3);
N(1)−Y(1)−N(2) = 55.8(1), N(3)−Y(1)−C(30) = 108.1(1), N(3)−
Y(1)−N(2) = 146.3(1).
Table 1. Crystallographic Data and Structure Refinement Details for 3 and 5−7
3
5
6
7
empirical formula
formula wt
cryst syst
space group
a, Å
C49H76N3O2SiY
856.13
C70H89N6Y
1103.38
C65H94N3O2Y
1038.34
C96H112H4Y2
1499.72
orthrohombic
Pbca
monoclinic
C2/c
triclinic
monoclinic
P21/m
P1
̅
17.1047(13)
19.2401(14)
29.473(2)
90
41.4345(11)
15.4298(4)
26.6797(7)
90
14.0702(14)
14.8777(16)
16.2464(17)
111.528(2)
94.874(2)
105.769(2)
2979.1(5)
2
12.5802(4)
27.1104(9)
24.6206(8)
90
b, Å
c, Å
α, deg
β, deg
90
128.250(1)
90
97.372(1)
90
γ, deg
V, Å3
90
9699.6(12)
8
13395.2(6)
8
8327.6(5)
4
Z
Dcalcd (g/cm3)
1.173
1.094
1.158
1.196
μ (mm−1
)
1.266
0.912
1.022
1.434
F(000)
3680
4720
1120
3176
cryst size, mm
2θ, deg
0.16 × 0.14 × 0.06
52
0.18 × 0.16 × 0.15
50
0.41 × 0.23 × 0.08
55
0.24 × 0.12 × 0.10
52
index ranges
−21 ≤ h ≤ 21
−23 ≤ k ≤ 23
−36 ≤ l ≤ 36
79 809
−49 ≤ h ≤ 49
−18 ≤ k ≤ 18
−31 ≤ l ≤ 31
51 618
−16 ≤ h ≤ 8
19 ≤ k ≤ 8
19 ≤ l ≤ 21
20 126
−15 ≤ h ≤ 15
−33 ≤ k ≤ 33
−30 ≤ l ≤ 30
72 470
no. of rflns collected
no. of indep rflns (Rint)
GOF on F2
9479 (0.3095)
0.867
11 638 (0.0820)
0.978
13 511 (0.0337)
1.022
16 692 (0.1785)
0.996
final R indices (I > 2σ(I))
R indices (all data)
largest diff in peak and hole, e/Å3
0.0615
0.0610
0.0538
0.0704
0.1250
0.1657
0.1204
0.1462
0.871/−1.080
0.616/−0.461
0.787/−0.469
2.181/−0.975
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Single-crystal samples of 5 suitable for X-ray analysis were
obtained by slow concentration of a toluene solution at ambient
temperature. The complex crystallizes as a solvate: 5·2C7H8.
Complex 5 crystallizes in the monoclinic C2/c space group with
eight molecules in the unit cell (one crystallographically
independent molecule in the asymmetric unit). The molecular
structure of complex 5 is shown in Figure 2, and the structure
bonds for anilido fragments in 5 are close to that in 3 (2.250(3)
Å). The coordination bonds between Y and the nitrogen atoms
of the 2,2′-bipy ligand (2.555(2) and 2.5428(18) Å) are slightly
shorter than the distance to the pyridinato nitrogen atom of the
Ap ligand. The 2,2′-bipy ligand is not planar. The value of the
dihedral angle between the pyridyl rings is 14.5°. The lengths of
covalent and coordination Y−N bonds determined in 5 fall into
the region normally observed for six-coordinated yttrium
complexes.19,15d
Rare-earth alkynyl complexes have attracted considerable
attention, due to the variety of bonding modes and metal-
mediated transformations of alkynyl ligands.14 Some of these
alkynyl complexes demonstrated high catalytic activity in the
dimerization of terminal alkynes to enynes.15d,20 In order to
synthesize a bis(alkynyl) yttrium species supported by an Ap
ligand, the reaction of 1 with 2 equiv of phenylacetylene was
1
attempted in C6D6 at ambient temperature under H and 13C
NMR control. When the reagents were mixed, the solution
color remained pale yellow while the 1H NMR spectrum
indicated that the reaction occurred with cleavage of both Y−
alkyl bonds and formation of 2 equiv of TMS. The preparative-
scale reaction was carried out in toluene. Unfortunately,
attempts to isolate the reaction product failed.
Rare-earth complexes proved to be excellent initiators for
alkene and alkyne hydroamination reactionsa promising path
for catalytic C−N bond formation.21 This prompted us to
synthesize yttrium complexes containing both alkynyl and
amido fragments and to explore their behavior in the metal
coordination sphere. The reaction of complex 3 with 1 equiv of
phenylacetylene in hexane at ambient temperature was found to
occur selectively with the protonation of the Y−alkyl bond,
elimination of TMS, and formation of the yttrium alkynyl
amido species 6 (Scheme 4).
Figure 2. Crystal structure of [ApY(NHAr)2(bipy)] (5). Thermal
ellipsoids are drawn at the 30% probability level. Hydrogen atoms,
methyl and isopropyl groups of Ap, and the anilido ligand are omitted
for clarity. Selected bond lengths (Å) and angles (deg): Y(1)−N(6) =
2.228(2), Y(1)−N(5) = 2.269(2), Y(1)−N(1) = 2.326(2), Y(1)−
N(2) = 2.497(2), Y(1)−N(4) = 2.525(2), Y(1)−N(3) = 2.555(2);
N(6)−Y(1)−N(5) = 111.29(7), N(1)−Y(1)−N(2) = 55.83(7),
N(4)−Y(1)−N(3) = 64.07(6).
Recrystallization of the reaction product from hexane
afforded complex 6 as a yellow crystalline solid in 81% yield.
The 1H and 13C NMR spectra of 6 present the expected sets of
signals characteristic for Ap and anilido fragments. The alkynyl
carbons give rise to two doublets in the 13C NMR spectrum:
1
2
142.90 (d, JYC = 66.0 Hz, CCPh) and 103.40 (d, JYC = 13.3
Hz, CCPh). Heating complex 6 in C6D6 to 60 °C does not lead
to an intramolecular reaction of the alkynyl and amido
fragments. Complex 6 turned out to be inert in the initiation
of hydroamination of phenylacetylene with aniline.
refinement data are given in Table 1. The X-ray diffraction
study of 5 revealed that the compound is monomeric in the
crystalline state. The yttrium ion is coordinated by two nitrogen
atoms of the chelating amidopyridinate ligand, two nitrogens of
chelating 2,2′-bipy, and two nitrogens of two monoanionic
anilido fragments, thus resulting in a coordination number of 6.
The distances between Y and the nitrogen atoms of
amidopyridinate ligand in 5 are nonequivalent: the distance
to the amido nitrogen (2.326(2) Å) is noticeably shorter than
that to the pyridinato nitrogen (2.497(2) Å). Both distances
exceed those to the nitrogen atoms of the monodentate anilido
fragments (2.228(2) and 2.269(2) Å). The values of Y−N
Transparent single-crystal samples of 6 suitable for an X-ray
diffraction study were obtained by slow concentration of a
cyclohexane solution at ambient temperature. Complex 6
crystallizes in the triclinic P1 space group with two molecules in
̅
the unit cell (one crystallographically independent molecule in
the asymmetric unit). The complex crystallizes as a solvate:
6·2C6H12. The molecular structure of complex 6 is shown in
Figure 3, and the structure refinement data are given in Table 1.
Scheme 4
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slightly bent (169.74(15)°). The Y−N bond lengths (for both
Ap and anilido ligands) in 6 and 3 have similar values.
The reaction of 6 with 1 equiv of 2,2′-bipy in toluene at
ambient temperature resulted in an immediate change of
solution color from pale yellow to brown. Unexpectedly,
similarly to the reaction of 3 with 2,2′-bipy, bis(anilido)
complex 5 was isolated from the reaction mixture in 43% yield
(Scheme 5). All attempts to isolate a complex containing
alkynyl ligands (or the product of their evolution) which could
be expected as a result of the ligand redistribution reaction were
unsuccessful.
We succeeded in isolating the product of treatment of
bis(alkyl) complex 2 supported by a bulky amidinate ligand
with phenylacetylene (hexane, 1:2 molar ratio, 20 °C). The
reaction resulted in a color change from pale yellow to
brownish red. Cooling of the concentrated reaction mixture at
−20 °C afforded red crystals of complex 7 (Scheme 6) in 78%
yield. Complex 7 is highly air- and moisture-sensitive. It is quite
soluble in THF and toluene and sparingly soluble in hexane.
Monocrystalline samples of 7 suitable for an X-ray diffraction
study were obtained by slow concentration of a benzene
solution at ambient temperature. Complex crystallizes as a
solvate: 7·0.5C6H6. Complex 7 crystallizes in the monoclinic
P21/m space group with four molecules in the unit cell.
Complex 7 contains two crystallographically independent
molecules in the asymmetric unit. Both molecules have similar
parameters; therefore, only one of them will be discussed. The
molecular structure of complex 7 is shown in Figure 4, and the
structure refinement data are given in Table 1.
The X-ray diffraction study revealed that complex 7 adopts a
symmetric dimeric structure (the molecule contains a plane of
symmetry) in which two AmdY fragments are linked by two
symmetric μ2-phenylacetylene ligands. Moreover, each of the
yttrium ions is η2 coordinated to the μ2-dialkynyl unit resulting
from coupling of two phenylacetylene ligands. The geometry
and bonding of the Ph2C4 ligand are of particular interest. The
C4 core is nearly linear, and the bond angles within the coupled
dialkynyl moiety are 176.4(2)°. The values of C−C bond
lengths within the C4 fragment (1.320(5), 1.281(7), and
1.320(5) Å) are typical for a double bond24 and clearly indicate
that the ligand is fully conjugated. Thus, the bonding situation
within the Ph2C4 bridging unit is best described as
butatrienediyl.25 The Ph2C4 ligand adopts a Z conformation,
with both yttrium atoms on the same side of the C4 chain. Two
carbon atoms of the phenylacetylene ligands are also in a
bridging site between two yttrium centers. It is worth noting
that such a geometry of a dialkynyl unit is very rare and only
one example has been described so far.26 Unlike the commonly
observed asymmetric bridging structure of a Ln2(CCR)2
core14b,26,27 in complex 7, the bond lengths between the
yttrium atoms and the carbons of μ2-phenylacetylene ligands
are very similar (2.467(4) and 2.490(4) Å). The distances from
Figure 3. Crystal structure of [ApY(CCPh)(NHAr)(DME)] (6).
Thermal ellipsoids are drawn at the 30% probability level. Hydrogen
atoms, methyl and isopropyl groups of Ap, and the anilido ligand are
omitted for clarity. Selected bond lengths (Å) and angles (deg): Y(1)−
N(3) = 2.228(1), Y(1)−N(1) = 2.312(1), Y(1)−N(2) = 2.487(1),
Y(1)−C(42) = 2.386(2), Y(1)−O(1S) = 2.416(2), Y(1)−O(2S) =
2.473(2), C(42)−C(43) = 1.209(3); C(43)−C(42)−Y(1) = 169.7(2),
N(1)−Y(1)−N(2) = 55.92(4), N(3)−Y(1)−C(42) = 104.99(6).
The X-ray diffraction study of 6 revealed that the compound
is monomeric and contains terminal alkynyl and anilido
fragments. The yttrium ion in 6 is coordinated by two nitrogen
atoms of the monoanionic chelating amidopyridinate ligand
and two oxygens of the DME molecule. Moreover, the yttrium
ion is covalently bonded to one carbon atom of the alkynyl
ligand and the nitrogen atom of the anilido fragment. The
formal coordination number of yttrium is 6, and its
coordination environment adopts a distorted-octahedral
geometry. Similarly to complexes 3 and 5, the distances
between Y and the nitrogen atoms of the amidopyridinate
ligand in 6 are nonequivalent: the distance to the amido
nitrogen (2.312(1) Å) is noticeably shorter than that to the
pyridinato nitrogen (2.487(1) Å). The both values exceed the
distance to the nitrogen atom of the anilido fragment (2.228(1)
Å). The Y(1)−C(42) distance in 6 (2.386(2) Å) is slightly
longer in comparison to the corresponding bond length in the
related six-coordinated yttrium complex [Me2Si(NCMe3)-
(OCMe3)]2YCCPh(THF), with a terminal alkynyl ligand
(2.448(4) Å),22 but noticeably shorter than that in the parent
complex 3. The CC bond lengths in 6 (1.209(3) Å) and
[Me2Si(NCMe3)(OCMe3)]2YCCPh(THF) (1.217(5) Å)22
have similar values. In seven-coordinated complexes the
distances between yttrium and carbon of terminal alkynyl
fragments are expectedly longer (2.412(3) Å23 and 2.456(4)
Å15d) than those in 6. The Y(1)−C(42)−C(43) moiety is
Scheme 5
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Scheme 6
regularity of the polymer. However, the chemical shift of the
signal assignable to vinylic protons and the integration of this
peak allows us to suggest a slightly predominant cis-transoidal
structure (∼70%).28 The presence of both cis and trans
contents in the polymer is supported by the IR spectrum, which
displays strong absorption bands at specific wavelengths (cis,
754, 1377 cm−1; trans, 1265 cm−1).
CONCLUSIONS
■
The reactions of bis(alkyl) yttrium complexes supported by
bulky NCN (amidopyridinate and amidinate) ligands with
reagents containing acidic N−H or C−H bonds were
investigated. The treatment of ApY(CH2SiMe3)2(THF) with
an equimolar amount of 2,6-diisopropylaniline afforded the
rather stable alkyl anilido species ApY(CH2SiMe3)(NH-
2,6-iPr2C6H3)(DME). No further intramolecular protonolysis
of the Y−C bond by NH of the anilido fragment and formation
of a terminal imido complex was detected. The reaction of
ApY(CH2SiMe3)(NH-2,6-iPr2C6H3)(DME) with PhCCH
(1:1 molar ratio) results in the selective protonolysis of the
Y−C bond and the formation of the alkynyl anilido derivative
ApY(CCPh)(NH-2,6-iPr2C6H3)(DME). No intra- or inter-
molecular additions of NH to CC were observed. Ligand
redistribution reactions and formation of the bis(anilido)
complex ApY(NH-2,6-iPr2C6H3)2(bipy) took place when
ApY(CH2SiMe3)(NH-2,6-iPr2C6H3)(DME) and ApY(C
CPh)(NH-2,6-iPr2C6H3)(DME) were treated with bipy. A
very unusual dimeric complex containing simultaneously two
symmetrically bridging alkynyl ligands and a μ-η2:η2-butatrie-
nediyl fragment, [{AmdY(μ2-CCPh)}2(μ2-η2:η2-
PhCCCCPh)], was obtained in the reaction of AmdY-
(CH2SiMe3)2(THF) with 2 equiv of phenylacetylene.
Figure 4. Crystal structure of [{AmdY(μ2-CCPh)}2(μ2-η2:η2-
PhCCCCPh)] (7). Thermal ellipsoids are drawn at the 30%
probability level. Hydrogen atoms and 2,6-diisopropylphenyl groups
of the Amd ligand are omitted for clarity. Selected bond lengths (Å)
and angles (deg): Y(1)−C(45) = 2.371(4), Y(1)−C(30) = 2.467(4),
Y(1)−C(38) = 2.490(4), Y(1)−C(44) = 2.688(3), Y(1)−Y(1A) =
3.5145(7), Y(1)−N(1) = 2.308(3), Y(1)−N(2) = 2.337(3), C(44)−
C(45) = 1.320(5), C(44)−C(44A) = 1.281(7); C(45)−C(44)−
C(44A) = 176.4(2), C(30)−C(31)−C(32) = 176.5(6), C(38)−
C(39)−C(40) = 178.8(5), Y(1A)−C(38)−Y(1) = 89.8(2), Y(1)−
C(30)−Y(1A) = 90.9(2).
yttrium atoms to carbons of the Ph2C4 fragment (2.371(4) and
2.688(3) Å) fall into the region previously reported for yttrium
complexes with coupled alkynyl ligands (2.283(4)−2.691(4)
Å).15b
Unlike the related butatrienediyl yttrium complex described
by Berg,26 the variable-temperature NMR spectroscopic studies
of 7 did not reveal any evidence for an equilibrium between
phenylacetylene and butatrienediyl species. The probable
mechanism of the coupling of two alkynyl ligands and the
formation of a butatrienediyl fragment bridging two lanthanide
centers was proposed by Marks and co-workers.14d
EXPERIMENTAL SECTION
■
All experiments were performed in evacuated tubes by using standard
Schlenk techniques, with rigorous exclusion of traces of moisture and
air. After being dried over KOH, THF was purified by distillation from
sodium/benzophenone ketyl; hexane and toluene were dried by
distillation from sodium/triglyme and benzophenone ketyl prior to
use. C6D6 was dried with sodium and condensed under vacuum into
NMR tubes prior to use. 2,6-Diisopropylaniline and phenylacetylene
were purchased from Acros and were dried over CaH2 and molecular
sieves, respectively. Anhydrous YCl3,29 Me3SiCH2Li,30 (Me3SiCH2)3Y-
(THF)2,31 and [ApY(CH2SiMe3)2(THF)]12 were prepared according
to literature procedures. All other commercially available chemicals
were used after the appropriate purifications. NMR spectra were
recorded with Bruker DPX 200 and Bruker Avance DRX-400
spectrometers in CDCl3 or C6D6 at 25 °C, unless otherwise stated.
Chemical shifts for 1H and 13C NMR spectra were referenced
internally to the residual solvent resonances and are reported relative
to TMS. IR spectra were recorded as Nujol mulls with a Bruker Vertex
70 instrument. SEC analysis was provided by a Knauer Smartline
chromatograph with Phenogel Phenomenex columns 5u (300 × 7.8
mm) 10∧4, 10∧5 and a Security Guard Phenogel column with RI and
Compound 7 initiates the polymerization of phenylacetylene
(40 °C, toluene, [initiator]:[monomer] = 200). The total
conversion was reached in 8 h, and the PPA was isolated in 86%
yield as a soluble pale yellow solid. The PPA was purified by
precipitation from a toluene−hexane mixture. The obtained
polymer has a number-average molecular weight of 13 500 and
1
rather large polydispersity (2.37). In the H NMR spectrum of
PPA the vinylic (5.86 ppm) and aromatic (6.76 and 6.97 ppm)
protons are presented by broad singlets; furthermore, the
signals observed in the 13C{1H} NMR spectrum (127.4, 139.2,
and 140.5 ppm) are also broadened. This indicates low
5354
dx.doi.org/10.1021/om300377h | Organometallics 2012, 31, 5349−5357

Organometallics
Article
UV detectors (254 nm). The mobile phase was THF, and the flow rate
was 2 mL/min. Columns were calibrated by Phenomenex Medium
and High Molecular Weight Polystyrene Standard Kits with peak
molecular weights from 2700 to 2 570 000 Da. Lanthanide metal
analyses were carried out by complexometric titration. The C, H, N
elemental analyses were performed in the microanalytical laboratory of
the G. A. Razuvaev Institute of Organometallic Chemistry.
6.8 Hz, CH(CH3)2, Ap), 3.11 (6H, s, OMe, DME), 3.16 (4H, m,
2
CH(CH3)2, anilido), 4.52 (2H, d, JYH = 1.6 Hz, NH, anilido), 5.87
3
3
(1H, d, JHH = 8.6 Hz, Ar, Ap), 6.09 (1H, d, JHH = 7.0 Hz, Ar, Ap),
6.80 (1H, dd, 3JHH = 8.6 Hz, 3JHH = 7.0 Hz, Ar, Ap), 6.86 (2H, t, 3JHH
= 6.5 Hz, Ar, anilido), 6.91 (2H, s, Ar, Ap), 6.99 (2H, s, Ar, Ap), 7.14
3
(4H, d, JHH = 8.5 Hz, Ar, anilido). 13C{1H} NMR (100 MHz, C6D6,
293 K): 19.5 (Me, Ap), 20.5 (Me, Ap), 22.2 (CH(CH3)2, Ap), 23.8
(br s, CH(CH3)2, anilido), 24.1 (CH(CH3)2, Ap), 27.9 (CH(CH3)2,
Ap), 28.6 (CH(CH3)2, anilido), 34.4 (CH(CH3)2, Ap), 61.8 (Me,
DME), 70.1 (CH2, DME), 107.1 (Ar, Ap), 110.9 (Ar, Ap), 115.3 (Ar,
anilido), 120.2 (Ar, Ap), 122.5 (Ar, anilido), 129.8 (Ar, Ap), 131.9 (d,
Synthesis of AmdY(CH2SiMe3)2(THF) (2). A solution of AmdLi
(0.652 g, 1.53 mmol) in THF (10 mL) was added to a suspension of
YCl3 (0.292 g, 1.49 mmol) in THF (30 mL). The reaction mixture was
stirred at 60 °C for 1 h, and THF was removed under vacuum. The
solid residue was dissolved in toluene (40 mL), and a solution of
Me3SiCH2Li (0.298 g, 3.17 mmol) in toluene (10 mL) wad added at 0
°C. The reaction mixture was stirred for 1 h, toluene was removed
under vacuum, and the solid residue was extracted with hexane. LiCl
was removed by filtration, and the solution was concentrated and kept
overnight at −18 °C. A 0.800 g amount of colorless crystals of
compound 2 was isolated (yield 71%). 1H NMR (400 MHz, C6D6, 293
2JYC = 2.2 Hz, Ar, Ap), 132.5 (Ar, Ap), 134.3 (Ar, anilido), 138.0 (Ar,
2
Ap), 140.4 (Ar, Ap), 144.1 (Ar, Ap), 148.7 (Ar, Ap), 151.7 (d, JYC
=
2
3.7 Hz, Ar, anilido), 155.2 (Ar, Ap), 168.3 (d, JYC = 2.2 Hz, NCN).
Synthesis of ApY(NHAr)2(bipy) (5). A solution of 2,2′-bipyridine
(0.098 g, 0.64 mmol) in toluene (5 mL) was added to a solution of 3
(0.548 g, 0.64 mmol) in toluene (15 mL) at room temperature. The
reaction mixture was stirred at room temperature for 0.5 h, and the
volatiles were removed under vacuum. The resulting solid residue was
dissolved in a new portion of toluene (5 mL). Slow concentration of
the solution at room temperature afforded brown crystals of 5 (0.29 g,
2
K): −0.29 (4H, d, JYH = 3.1 Hz, YCH2), 0.24 (18H, s, SiMe3), 0.97
3
(9H, s, tBu), 1.14 (4H, br s, β-CH2, THF), 1.35 (12H, d, JHH = 6.8
Hz, CH(CH3)2), 1.38 (12H, d, 3JHH = 6.7 Hz, CH(CH3)2), 3.44 (4H,
br s, α-CH2, THF), 3.62 (4H, sept, 3JHH = 6.8 Hz, CH(CH3)2), 6.98−
7.12 (6H, m, Ar). 13C{1H} NMR (100 MHz, C6D6, 293 K): 4.0
(SiMe3), 23.2 (CH(CH3)2), 24.3 (β-CH2, THF), 26.6 (CH(CH3)2),
1
45%). H NMR (400 MHz, C6D6, 293 K): 0.90−1.35 (42H, complex
m, CH(CH3)2 Ap and anilido), 2.32 (3H, s, Me, Ap), 2.54 (6H, s, Me,
3
Ap), 2.63 (1H, sept, JHH = 6.8 Hz, CH(CH3)2, Ap), 2.82 (2H, br s,
1
28.4 (CH(CH3)2), 30.5 (C(CH3)3), 39.0 (d, JYC = 40.7 Hz, YCH2),
CH(CH3)2, Ap), 3.03 (4H, br s, CH(CH3)2, anilido), 4.77 (2H, br s,
NH), 5.95 (1H, d, 3JHH = 7.0 Hz, Ar, Ap), 5.98 (1H, d, 3JHH = 8.6 Hz,
Ar, Ap), 6.45 (2H, t, 3JHH = 5.7 Hz, Ar, bipy), 6.53 (2H, br s, Ar, bipy),
44.7 (d, 3JYC = 2.9 Hz, CMe3), 70.0 (α-CH2, THF), 123.7 (Ar), 124.1
2
(Ar), 141.7 (Ar), 144.1 (Ar), 180.4 (d, JYC = 2.4 Hz, NCN). IR
3
(KBr): 1915 (w), 1864 (w), 1805 (w), 1617 (m), 1587 (w), 1433 (s),
1400 (s), 1366 (s), 1311 (m) 1274 (w), 1248 (m), 1235 (m), 1212
(m), 1171 (s), 1098 (m), 1057 (w), 1040 (m), 1012 (m), 952 (w),
932 (w), 864 (s), 818 (m), 803 (m), 776 (w), 763 (s), 745 (m), 671
(s), 645 (w), 605 (w), 588 (w), 543 (w), 535 (w), 521 (w) cm−1. Anal.
Calcd for C90H106N4Y2 (1421.64): C, 65.21; H, 9.74; Y, 11.77. Found:
C, 64.85; H, 9.60; Y, 11.53.
6.74 (2H, t, JHH = 7.4 Hz, Ar, anilido), 6.79−6.82 (1H, complex m,
Ar, Ap), 6.84−6.92 (4H, complex m, Ar, Ap), 6.97−7.05 (6H, complex
m, Ar, Ap and anilido), 8.81 (2H, s, Ar, bipy). 13C{1H} NMR (100
MHz, C6D6, 293 K): 19.6 (Me, Ap), 20.6 (Me, Ap), 22.2 (CH(CH3)2,
Ap), 23.6 (CH(CH3)2, anilido), 26.1 (CH(CH3)2, Ap), 28.8
(CH(CH3)2, anilido), 29.9 (CH(CH3)2, Ap), 33.9 (CH(CH3)2, Ap),
106.7 (Ar, Ap), 111.3 (Ar, Ap), 114.4 (Ar, anilido), 119.6 (Ar, bipy),
120.3 (Ar, Ap), 122.1 (Ar, anilido), 125.0 (Ar, bipy), 129.8 (Ar, Ap),
131.7 (Ar, Ap), 132.5 (Ar, Ap), 133.9 (Ar, anilido), 136.3 (Ar, bipy),
138.0 (Ar, Ap), 138.4 (Ar, bipy), 144.8 (Ar, Ap), 145.8 (Ar, Ap), 146.9
(Ar, Ap), 151.1 (Ar, bipy), 152.2 (Ar, Ap), 152.6 (d, 2JYC = 3.5 Hz, Ar,
Synthesis of ApY(CH2SiMe3)(NHAr)(DME) (3). To a solution of
1 (0.426 g, 0.57 mmol) in hexane (30 mL) was added a solution of
2,6-diisopropylaniline (0.101 g, 0.57 mmol) in hexane (10 mL) at
room temperature, and the reaction mixture was stirred for 1 h.
Volatiles were removed under vacuum, and the solid residue was
recrystallized from DME at −20 °C to give 0.35 g (72%) of pale
yellow crystals of 3. 1H NMR (400 MHz, C6D6, 293 K): −0.42 (2H, d,
2JYH = 36.5 Hz, CH2Y), 0.37 (9H, s, SiMe3), 1.01−1.34 (30H, complex
m, CH(CH3)2, Ap and anilido), 2.19 (3H, s, Me, Ap), 2.29 (3H, s, Me,
Ap), 2.30−2.38 (2H, br s, CH2, DME), 2.60−2.84 (8H, complex m,
2
anilido), 155.8 (Ar, Ap), 168.6 (d, JYC = 2.2 Hz, NCN). IR (KBr):
3385 (w), 3051 (w), 1604 (m), 1585 (s), 1545 (m), 1421 (s), 1357
(m), 1317 (m), 1246 (s), 1216 (m), 1171 (w), 1156 (m), 1113 (w),
1098 (w), 1059 (w), 1041 (w), 1018 (m), 990 (m), 884 (w), 874 (w),
855 (m), 837 (m), 796 (m), 764 (m), 743 (s), 682 (w), 649 (w), 629
(w), 584 (w), 562 (w), 533 (w) cm−1. Anal. Calcd for C63H81N6Y:
(1011.26): C, 74.82; H, 8.07; Y, 8.79. Found: C, 75.02; H, 8.35; Y,
8.93.
3
CH(CH3)2, Ap; Me, Ap; CH2, DME), 2.87 (2H, sept, JHH = 6.7 Hz,
CH(CH3)2, anilido), 3.00 (6H, s, Me, DME), 4.68 (1H, s, NH), 5.83
(1H, d, 3JHH = 8.6 Hz, m-H, Py, Ap), 6.07 (1H, d, 3JHH = 7.5 Hz, m-H,
Synthesis of ApY(CCPh)(NHAr)(DME) (6). A solution of
HCCPh (0.053 g, 0.52 mmol) in hexane (10 mL) was added to a
solution of 3 (0.445 g, 0.52 mmol) in hexane (20 mL) at room
temperature. The reaction mixture was stirred at room temperature for
1 h. Hexane was removed under vacuum, and the solid residue was
recrystallized from hot cyclohexane. Complex 6 was isolated as a
py, Ap), 6.81 (1H, t, 3JHH = 7.5 Hz, p-H, anilido), 6.85 (1H, dd, 3JHH
=
8.5 Hz, 3JHH = 7.1 Hz, p-H, Py, Ap), 6.99 (4H, complex m, m-H, Ap),
3
7.1 (2H, d, JHH = 7.5 Hz, m-H, anilido). 13C{1H} NMR (100 MHz,
C6D6, 293 K): 4.2 (Me3Si), 18.8 (br s, Me, Ap), 20.5 (Me, Ap), 23.5
(br s, CH(CH3)2), 24.2 (CH(CH3)2), 26.0 (CH(CH3)2), 26.9
(CH(CH3)2), 28.8 (CH(CH3)2, anilido), 30.1 (CH(CH3)2, Ap),
1
yellow crystalline solid in 81% yield (0.37 g). H NMR (400 MHz,
C6D6, 293 K): 1.10 (6H, d, 3JHH = 6.8 Hz, CH(CH3)2, Ap), 1.13 (4H,
1
31.7 (d, JYC = 43.4 Hz, YCH2), 34.6 (CH(CH3)2, Ap), 61.8 (CH3,
3
3
d, JHH = 6.8 Hz, CH(CH3)2, anilido), 1.21 (8H, d, JHH = 6.9 Hz,
CH(CH3)2, Ap), 1.23−1.32 (12H, br s, CH(CH3)2, Ap and anilido),
2.26 (3H, s, Me, Ap), 2.46−2.67 (10H, br s, Me, Ap and CH2, DME),
2.78 (4H, sept, 3JHH = 6.7 Hz, CH(CH3)2, Ap and anilido), 3.12 (1H,
br s, CH(CH3)2, Ap), 3.29 (6H, s, Me, DME), 5.03 (1H, d, 3JYH = 1.7
DME), 70.2 (CH2, DME), 105.7 (Ar), 110.4 (Ar), 114.5 (Ar), 120.2
(Ar), 122.3 (Ar), 129.8 (Ar), 132.1 (Ar), 133.4 (Ar), 137.4 (Ar), 138.3
2
(Ar), 144.1 (d, JYC = 1.3 Hz, Ar, Ap), 147.0 (Ar), 148.6 (Ar), 152.0
2
2
(d, JYC = 3.4 Hz, Ar, anilido), 154.9 (Ar), 168.4 (d, JYC = 2.2 Hz,
NCN Ap). IR (KBr): 3385 (w), 1586 (m), 1547 (m), 1423 (m), 1361
(s), 1322 (w), 1281 (w), 1249 (s), 1154 (m), 1098 (m), 1050 (s), 994
(m), 858 (s), 798 (m), 677 (w), 660 (w), 624 (w), 565 (w), 535 (w)
cm−1. Anal. Calcd for C49H76N3O2SiY (856.14): C, 68.74; H, 8.95; Y,
10.38. Found: C, 68.31; H, 9.51; Y, 10.62.
Hz, NH anilido), 5.84 (1H, d, 3JHH = 8.5 Hz, Ar), 6.08 (1H, d, 3JHH
=
6.9 Hz, Ar, Ap), 6.83 (1H, t, 3JHH = 7.5 Hz, Ar, anilido), 6.89 (1H, dd,
3JHH = 8.5 Hz, 3JHH = 7.1 Hz, Ar, Ap), 6.95 (2H, s, Ar, Ap), 6.98 (1H,
3
d, JHH = 7.4 Hz, Ar, PhC2), 7.04−7.10 (4H, m, Ar, Ap and PhC2),
Synthesis of ApY(NHAr)2(DME) (4). 2,6-Diisopropylaniline
7.13 (2H, s, Ar, anilido), 7.54−7.59 (2H, m, Ar, PhC2). 13C{1H} NMR
(100 MHz, C6D6, 293 K): 19.6 (Me, Ap), 20.6 (Me Ap), 22.2
(CH(CH3)2, anilido), 22.5 (CH(CH3)2, anilido), 23.8 (CH(CH3)2,
Ap), 24.2 (CH(CH3)2, Ap), 26.5 (CH(CH3)2, Ap), 29.7 (CH(CH3)2,
anilido), 30.3 (CH(CH3)2, Ap), 34.6 (CH(CH3)2, Ap), 62.5 (Me,
DME), 70. Five (CH2, DME), 103.4 (d, 2JYC = 13.3 Hz, CCPh), 104.8
(Ar, Ap), 110.0 (Ar, Ap), 114.3 (Ar, anilido), 120.2 (Ar, Ap), 122.5
(0.007 g, 0.04 mmol) was added to a solution of 3 (0.034 g, 0.04
1
mmol) in C6D6 (0.6 mL) at room temperature. H NMR (400 MHz,
C6D6, 293 K): 1.14 (12H, d, 3JHH = 6.8 Hz, CH(CH3)2, Ap), 1.18 (6H,
d, 3JHH = 6.9 Hz, CH(CH3)2, Ap), 1.23 (24H, m, CH(CH3)2, anilido),
2.24 (3H, s, Me Ap), 2.37 (6H, s, Me Ap), 2.48 (4H, br s, CH2, DME),
2.62 (2H, sept, 3JHH = 6.8 Hz, CH(CH3)2, Ap), 2.76 (1H, sept, 3JHH
=
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dx.doi.org/10.1021/om300377h | Organometallics 2012, 31, 5349−5357

Organometallics
Article
(Ar, anilido), 122.8 (Ar, PhC2), 125.7 (Ar, PhC2), 127.9 (Ar, PhC2),
129.5 (Ar, Ap), 131.8 (Ar, PhC2), 132.3 (Ar), 132.65 (Ar), 137.24
(Ar), 138.9 (Ar), 142.9 (d, JYC = 66.0 Hz, CCPh), 143.5 (Ar), 148.5
ASSOCIATED CONTENT
* Supporting Information
Figures giving NMR spectra and CIF files giving crystallo-
graphic data. This material is available free of charge via the
Internet at http://pubs.acs.org.
■
S
1
(Ar), 152.5 (d, 3JYC = 3.7 Hz, Ar, PhC2), 154.7 (Ar, Ap), 168.8 (d, 2JYC
= 2.3 Hz, Ar, Ap). IR (KBr): 3390 (w), 2048 (w), 1589 (m), 1547
(m), 1364 (m), 1254 (m), 1195 (w), 1154 (m), 1100 (w), 1053 (m),
1027 (w), 991 (m), 858 (m), 796 (m), 778 (w), 757 (m), 742 (m),
692 (w), 654 (w), 627 (w), 532 (w) cm−1. Anal. Calcd for
C53H70N3O2Y: C, 73.16; H, 8.11; Y, 10.22. Found: C, 72.81; H,
8.01; Y, 10.50.
AUTHOR INFORMATION
Corresponding Author
*E-mail: trif@iomc.ras.ru. Fax:(+7)8314621497.
■
Synthesis of [{AmdY(μ2-CCPh)}2(μ2-η2:η2-PhCCCCPh)] (7). A
solution of phenylacetylene (0.052 g, 0.50 mmol) in hexane (5 mL)
was added to a solution of 2 (0.203 g, 0.25 mmol) in hexane (15 mL)
at room temperature. The reaction mixture was stirred for 2 h at 20
°C, concentrated, and kept overnight at −18 °C. Complex 7 was
isolated as a red crystalline solid in 78% yield (0.27 g). 1H NMR (400
MHz, C6D6, 293 K): 0.97 (12H, br s, CH(CH3)2), 1.04 (18H, s,
CMe4), 1.16 (12H, br s, CH(CH3)2), 1.37 (12H, br s, CH(CH3)2),
1.41 (12H, br s, CH(CH3)2), 3.68 (4H, br s, CH(CH3)2), 3.93 (4H, br
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work has been supported by the Russian Foundation for
Basic Research (Grant No. 11-03-00555-a), the Program of the
Presidium of the Russian Academy of Science (RAS), and the
RAS Chemistry and Material Science Division.
3
s, CH(CH3)2), 5.80 (4H, d, JHH = 7.2 Hz, o-Ar, PhC2), 6.75 (12H,
REFERENCES
■
complex m, m-Ar, PhC2 and Am), 6.91 (6H, complex m, p-Ar PhC2
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= 7.7 Hz, m-Ar, PhC4Ph), 8.13 (4H, d, 3JHH = 7.1 Hz, o-Ar, PhC4Ph).
13C{1H} NMR (100 MHz, C6D6, 293 K): 21.8 (CH(CH3)2)), 22.3
(CH(CH3)2)), 24.9 (CH(CH3)2)), 26.2 (CH(CH3)2)), 28.7 (CH-
(CH3)2)), 29.2 (CH(CH3)2)), 30.3 (C(CH3)3), 44.9 (CMe3), 120.8
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1
PhC2), 137.6 (t, JYC = 27.8 Hz, PhCC), 141.0 (i-Ar, PhC4Ph), 141.9
2
(i-Ar, Am), 144.0 (o-Ar, Am), 171.7 (d, JYC = 3.4 Hz, PhCCCCPh),
180.7 (d, 2JYC = 2.4 Hz, NCN), 186.7 (d, 1JYC = 49.0 Hz, PhCCCCPh).
IR (KBr): 3060 (s), 3009 (s), 2279 (w), 2050 (m), 2038 (m), 1958
(w), 1911 (w), 1853 (w), 1815 (w), 1719 (w), 1668 (w), 1656 (w),
1619 (m), 1586 (m), 1569 (w), 1540 (s), 1486 (s), 1434 (s), 1410 (s),
1396 (s), 1365 (s), 1321 (w), 1304 (w), 1246 (m), 1212 (m), 1173
(s), 1102 (m), 1070 (w), 1059 (w), 1044 (m), 1026 (w), 998 (w), 955
(m), 932 (w), 915 (w), 883 (w), 837 (m), 800 (m), 754 (s), 719 (m),
689 (s), 640 (m), 623 (w), 609 (w), 584 (w), 549 (m), 540 (w), 500
(s), 467 (m) cm−1. Anal. Calcd for C90H106N4Y2: C, 76.04; H, 7.52; Y,
12.51. Found: C, 75.85; H, 7.63; Y, 12.86.
Polymerization of Phenylacetylene. A Schlenk flask was
charged with 7 (28.0 mg, 20.0 μmol), phenylacetylene (0.408 g,
4.00 mmol), and toluene (10.0 mL). The mixture was stirred at 40 °C
for 8 h. The reaction was quenched by adding ca. 1.0 mL of a 10%
H2O solution in THF, and the polymer was precipitated from toluene/
hexane (ca. 1/20 mL). The polymer was then filtered and dried in
vacuo to a constant weight (0.347 g, 86.4%).
X-ray Crystallography. The X-ray data for 3 and 5−7 were
collected on a SMART APEX diffractometer (graphite-monochro-
mated Mo Kα radiation, ω-scan technique, λ = 0.710 73 Å, T = 100
K). The structures were solved by direct methods and were refined on
F2 using the SHELXTL32 package. All non-hydrogen atoms and H
atoms in NH groups of anilido fragments in 5 and 6 were found from
Fourier syntheses of electron density and were refined anisotropically.
All other hydrogen atoms were placed in calculated positions and were
refined in the riding model. SADABS33 was used to perform area-
detector scaling and absorption corrections. The details of crystallo-
graphic, collection, and refinement data are shown in Table 1, and the
corresponding CIF files are available as Supporting Information.
CCDC-874678 (3), CCDC-874679 (5), CCDC-874680 (6), and
CCDC-874681 (7) 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.
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