Yttrium complexes featuring different Y-C bonds. Comparative reactivity studies: Toward terminal imido complexes

Article abstract of DOI:10.1021/om400099z

The reactions of 2,6-diisopropylaniline with equimolar amounts of alkyl-heteroaryl yttrium complexes containing Y-C(sp³, alkyl) along with Y-C(sp², heteroaryl) bonds resulting from intramolecular C-H bond activation of the amido-pyridinate ligands [NNO^BzFur]YCH ₂SiMe₃(THF)₂, [NNS^BzTh]YCH ₂SiMe₃(THF)₂, and [NNS^EtTh]YCH ₂SiMe₃(THF)₂ have been scrutinized with the aim of synthesizing yttrium terminal imido species. These reactions occur at ambient temperature with the protonolysis of the Y-C(sp³, alkyl) bond, thus affording anilido-heteroaryl species and maintaining the residual Y-C(sp², heteroaryl) bond untouched. However, the subsequent transformation of the as-synthesized anilido-heteroaryl complexes depends on the nature of the substituent on the 6-position of the pyridyl ring. In the case of the benzofuryl yttrium derivative [NNO^BzFur]YNH-2,6- ⁱPr₂C₆H₃(THF)₂ (4), heating to 50 C results in benzofuran ring opening with the formation of an anilido species supported by a dianionic amido-yne-phenolate ligand framework, [NNCi - CO]YNH-2,6-ⁱPr₂C₆H ₃(THF) (6). In contrast, a complex containing a benzothiophenyl moiety, [NNS^BzTh]YNH-2,6-ⁱPr₂C ₆H₃(THF)₂ (7), slowly undergoes protonation of the Y-C(sp², heteroaryl) bond and a ligand redistribution reaction takes place, affording an yttrium bis(anilido) species supported by a monoanionic amido-pyridinate ligand featuring intramolecular Y-S heteroaryl coordination, [NNS^BzTh]Y[NH-2,6-ⁱPr₂C ₆H₃]₂ (9). It is worth noting that an yttrium complex containing α-thiophenyl fragment, [NNS^EtTh]YNH-2,6- ⁱPr₂C₆H₃(THF)₂ (10), turned out to be extraordinarily robust and no transformation was ever detected even upon heating the complex at 100 C for prolonged times.

Full text of DOI:10.1021/om400099z

Article
pubs.acs.org/Organometallics
Yttrium Complexes Featuring Different Y−C Bonds. Comparative
Reactivity Studies: Toward Terminal Imido Complexes
Alexander A. Karpov,† Anton V. Cherkasov,† Georgy K. Fukin,† Andrei S. Shavyrin,† Lapo Luconi,‡
Giuliano Giambastiani,‡ 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
‡Institute of Chemistry of OrganoMetallic Compounds, ICCOM-CNR, Via Madonna del Piano, 10, 50019 Sesto Fiorentino
(Florence), Italy
S
* Supporting Information
ABSTRACT: The reactions of 2,6-diisopropylaniline with equimolar amounts
of alkyl−heteroaryl yttrium complexes containing Y−C(sp3, alkyl) along with
Y−C(sp2, heteroaryl) bonds resulting from intramolecular C−H bond
activation of the amido−pyridinate ligands [NNOBzFur]YCH2SiMe3(THF)2,
[NNSBzTh]YCH2SiMe3(THF)2, and [NNSEtTh]YCH2SiMe3(THF)2 have been
scrutinized with the aim of synthesizing yttrium terminal imido species. These
reactions occur at ambient temperature with the protonolysis of the Y−C(sp3,
alkyl) bond, thus affording anilido−heteroaryl species and maintaining the
residual Y−C(sp2, heteroaryl) bond untouched. However, the subsequent
transformation of the as-synthesized anilido−heteroaryl complexes depends
on the nature of the substituent on the 6-position of the pyridyl ring. In the
case of the benzofuryl yttrium derivative [NNOBzFur]YNH-
2,6-iPr2C6H3(THF)2 (4), heating to 50 °C results in benzofuran ring opening
with the formation of an anilido species supported by a dianionic amido−yne−phenolate ligand framework, [NNCCO]YNH-
2,6-iPr2C6H3(THF) (6). In contrast, a complex containing a benzothiophenyl moiety, [NNSBzTh]YNH-2,6-iPr2C6H3(THF)2 (7),
slowly undergoes protonation of the Y−C(sp2, heteroaryl) bond and a ligand redistribution reaction takes place, affording an
yttrium bis(anilido) species supported by a monoanionic amido−pyridinate ligand featuring intramolecular Y−S heteroaryl
coordination, [NNSBzTh]Y[NH-2,6-iPr2C6H3]2 (9). It is worth noting that an yttrium complex containing α-thiophenyl fragment,
[NNSEtTh]YNH-2,6-iPr2C6H3(THF)2 (10), turned out to be extraordinarily robust and no transformation was ever detected even
upon heating the complex at 100 °C for prolonged times.
rare-earth complex with a terminal imido ligand.5 Complexes
INTRODUCTION
■
containing a double nitrogen−metal bond have important
Rare-earth complexes containing M−C σ bonds still deserve
particular interest as highly active species that exhibit unique
synthetic potentialities due to the ability of the MN
functional group to undergo several reactions/transformations
reactivity1 and ability to promote activation and derivatization
(metathesis of imines and carbodiimides, metallacycle for-
of unsaturated2 and saturated3 substrates. Recently we have
mation with alkynes and alkenes, and C−H bond activation).6
reported how the reaction of an equimolar amount of
[Y(CH2SiMe3)3(thf)2] with aminopyridine ligands bearing
It is worth noting that, unlike the well-established imido
chemistry based on transition metals,7 that of rare-earth metals
aryl or heteroaryl substituents at the 6-position of the pyridine
is still in its infancy.8 Synthetic difficulties are basically related
ring results in quantitative intramolecular sp2 or sp3 C−H bond
to the pronounced tendency of these large metal ions to
activations. These reactions proved to be a useful synthetic
assemble in the form of more stable bi- or polymetallic
approach, allowing for the convenient synthesis of novel
complexes with μ2-imido ligands.8,9 Several examples of C−H
yttrium complexes featuring the simultaneous presence of two
bond activation resulting from the transformation of terminal
different Y−C bonds (Y−benzyl, Y−aryl, or Y−heteroaryl
imido rare-earth complexes have been also documented.8d,f
together with Y−alkyl).4 Notably, the Y−C bonds in the
Bulky polydentate ligands able to provide kinetic stability to the
final imido species may be employed in order to overcome
isolated complexes showed different reactivities: i.e., upon
complex treatment with an excess of PhSiH3, a σ-bond
these synthetic limitations. Accordingly, the aforementioned
metathesis reaction took place selectively on the residual Y−
alkyl−heteroaryl yttrium complexes4 coordinated by amidopyr-
alkyl bonds, leading to the formation of unique yttrium aryl−-
hydrido, benzyl−hydrido, and heteroaryl−hydrido species.
Chen et al. reported in 2010 on the synthesis and
Received: February 4, 2013
characterization of the first (and still the only) example of a
© XXXX American Chemical Society
A
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Chart 1. Yttrium Alkyl−Heteroaryl Complexes Containing Potentially Coordinative S and O Donor Sites
idinate ligands represent good candidates for the synthesis of
related derivatives bearing terminal imido fragments via
reaction with sterically demanding anilines. Indeed, the
stabilization of the terminal imido species would potentially
be assisted from an intramolecular coordination of either S
(soft) or O (hard) donors belonging to the tridentate
amidopyridinate system (N,N,O or N,N,S) itself; the Y−
C(heteroaryl) bond protonolysis carried out by the aniline
reagent would render accessible those ligand donor sites not
available in the former species. In this regard, inspired by the
challenging synthesis of rare-earth terminal imido complexes,
we have explored the reactions of yttrium alkyl−heteroaryl
complexes with 2,6-diisopropylaniline.
Scheme 1. Synthesis of the Anilido Complex 4 and Its
Subsequent Thermal Rearrangement (Furyl Ring Opening)
to Complex 6 Stabilized by a Dianionic Amido−Yne−
Phenolate Ligand
RESULTS AND DISCUSSION
■
In order to prepare terminal imido yttrium species, we
attempted the reactions of equimolar amounts of alkyl−
heteroaryl complexes 1−3 (Chart 1) with 2,6-diisopropylani-
line. As the crucial role of a Lewis base coordination to the
metal center is emphasized as a prerequisite for the formation
of terminal imido complexes,5 we fix upon the use of tridentate
ligands combining both hard/hard (N,O) and hard/soft (N,S)
basic centers (Chart 1).
The NMR-tube reaction of 1 with 2,6-diisopropylaniline was
carried in C6D6 at ambient temperature. The disappearance of
the doublet at −0.69 ppm (attributed to the hydrogen atoms of
the residual methylene group bound to the yttrium center) and
the concomitant release of SiMe4 were indicative of Y−C(alkyl)
bond protonolysis. Furthermore, the persistence (in the
13C{1H} NMR spectrum) of a doublet centered at 157.3
ppm (1JYC = 40.0 Hz) assigned to the sp2 carbon of the
benzofuryl moiety σ-bonded to the metal center, together with
the appearance (in the 1H NMR spectrum) of a doublet at 5.10
ppm (2JYH = 2.2 Hz), characteristic for an NH anilido proton,17
supported the formation of the benzofuryl−anilido species 4
(Scheme 1).
An X-ray diffraction study showed that the anilido complex 6
contains a dianionic amido−yne−phenolate ligand (Figure 1).
Complex 6 crystallizes as a solvate species (6·C7H8). Due to the
furyl fragment ring opening an 11-membered chelating amido−
yne−phenolate group metallacycle was formed. This metallo-
cycle is not planar, the maximum deviation of the atoms from
its plane being 0.690(1) Å. The yttrium atom in 6 is covalently
bonded with one oxygen and one nitrogen atom from the
amido−yne−phenolate framework (Y(1)−O(1) = 2.1808(9)
Å, Y(1)−N(1) = 2.244(1) Å), while the nitrogen of the
pyridine fragment forms with yttrium a coordinative bond
(Y(1)−N(2) = 2.409(1) Å). Due to covalent bonding with the
anilido fragment (Y(1)−N(3) = 2.203(1) Å) and coordination
of one THF molecule, the coordination number at the yttrium
is 5. The complex adopts a distorted-square-pyramidal
coordination geometry, whose base is set up by the N and O
atoms from the amido−yne−phenolate moiety and one O atom
from a THF molecule. The covalent Y−N bonds in 6 are
somewhat nonequivalent, but their values are comparable to
those reported for related amides on five-coordinated yttrium10
complexes. The Y−O bond length is also in a good agreement
with the values reported for five-coordinated yttrium
alkoxides.10b,11 The angles around carbon atoms C(21) and
C(22) (C(21)−C(22)−C(23) = 173.3(2)°, C(20)−C(21)−
C(22) = 163.9(2)°) are consistent with a Csp hybridization of
the acetylenic moiety. The corresponding C(21)−C(22) bond
distance of 1.200(2) Å is also in agreement with triple-bond
character.12 The C(23)−C(24) bond length (1.410(2) Å) is
1
Complex 4 was isolated and completely characterized by H
and 13C{1H} NMR spectroscopy and microanalysis. Following
the behavior of 4 in C6D6 solution at room temperature by 1H
NMR spectroscopy revealed that neither decomposition nor
further transformation took place even after several days. In
contrast, when the complex solution temperature was raised to
50 °C, a relatively rapid conversion of 4 into a new species was
observed (50% of conversion within 15 h).
The preparative-scale reaction of 1 with 2,6-diisopropylani-
line was carried out in a toluene/hexane mixture (toluene/
hexane 1/4) at room temperature, and the mixture was then
heated at 50 °C for 30 h. The reaction mixture turned from
yellow to deep red, and yellowish orange crystals suitable for X-
ray analysis were isolated in 54% yield after cooling the mixture
to −20 °C.
B
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Scheme 2. Synthesis of the Anilido Complexes 7 and 8
toluene and THF afforded the benzothiophenyl−amido
complex 7, which was isolated as a yellow crystalline solid in
78% yield (Scheme 2). Complex 7 was characterized by 1H and
13C{1H} NMR spectroscopy and microanalysis. Unfortunately,
all our attempts to obtain single crystals of 7 suitable for X-ray
diffraction studies failed. Nevertheless, the treatment of 7 with
pyridine and its subsequent recrystallization from benzene
allowed for the isolation of the bis(pyridine) adduct 8, which
was characterized by an X-ray diffraction study (Figure 2). The
Figure 1. Molecular structure of complex 6 with 30% probability
ellipsoids. The Pr substituents of the aminopyridinate ligand, the
i
methylene groups of THF molecules, and hydrogen atoms are omitted
for clarity. Selected distances (Å) and angles (deg): Y(1)−O(1) =
2.1808(9), Y(1)−O(2) = 2.361(1), Y(1)−N(1) = 2.244(1), Y(1)−
N(2) = 2.409(1), Y(1)−N(3) = 2.203(1), O(1)−C(24) = 1.321(2),
C(20)−C(21) = 1.432(2), C(21)−C(22) = 1.200(2), C(22)−C(23)
= 1.425(2), C(23)−C(24) = 1.410(2); C(20)−C(21)−C(22) =
163.9(2), C(21)−C(22)−C(23) = 173.3(2).
characteristic for aromatic C−C bonds.12 The single bonds next
to the triple bond (C(22)−C(23) = 1.425(2) Å) and C(20)−
C(21) = 1.432(2) Å) show distances within the range for those
in eneynes.13
Additionally, an intense band at 2250 cm−1 in the Raman
spectrum of complex 6 gives further evidence of the presence of
a triple bond.29
Furan ring-opening reactions, triggered by intramolecular
C−H bond activation in alkyl and heteroaryl species, have been
reported in a few cases.14 Formation of complex 6 can be
rationalized by a sequence of transformations of the
benzofuryl−amido species 4, a reliable representation of
which is provided in Scheme 1. First, an intramolecular
protonolysis of the Y−C(heteroaryl) bond promoted by the
residual proton of the NH amido function takes place, leading
to the formation of the terminal imido complex 5 (Scheme 1).
Afterward, the transient terminal imido complex undergoes
rapid intramolecular C−H bond activation, leading to the ring
opening of the furyl cycle with the generation of 6. It is worth
noting that, when the reaction course of the thermal
rearrangement of 4 is followed by NMR spectroscopy, no
signals attributed to the transient terminal imido species 5 were
ever detected, thus revealing an extremely short lifetime (on the
NMR time scale) of the imido intermediate itself.
Aiming at stabilizing the terminal imido species as well as
evaluating the general character of this heterocycle ring-opening
reaction, we have investigated the reaction of 2,6-diisopropy-
laniline with the analogous thio analogue 2 (Scheme 2). The
coordination of a soft Lewis base along with a lower energy of
the covalent Y−S bond (in comparison to that of Y−O)15 was
thought to be beneficial to the final stabilization of the expected
terminal imido yttrium species. It is worth noting that we found
a dramatic impact on the reaction outcome by the replacement
of the benzofuryl fragment with the benzothiophenyl fragment.
Indeed, the reaction of 2 with 2,6-diisopropylaniline in both
Figure 2. Molecular structure of complex 8 with 30% probability
ellipsoids. The Pr substituents in the aminopyridinate and aniline
i
ligands, the CH groups of the Py molecules, and hydrogen atoms are
omitted for clarity. Selected distances (Å) and angles (deg): Y(1)−
N(1) = 2.253(2), Y(1)−N(2) = 2.475(2), Y(1)−N(3) = 2.481(2),
Y(1)−N(4) = 2.506(3), Y(1)−N(5) = 2.293(2), Y(1)−C(22) =
2.551(3); N(1)−Y(1)−N(2) = 67.64(8), N(1)−Y(1)−N(5) =
94.81(9), N(1)−Y(1)−N(3) = 102.73(8), N(1)−Y(1)−N(4) =
107.18(9), N(2)−Y(1)−N(3) = 98.81(8), N(2)−Y(1)−N(4) =
90.03(9), N(2)−Y(1)−N(5) = 160.90(8), N(3)−Y(1)−N(5) =
92.22(9), N(4)−Y(1)−N(5) = 88.10(9).
proton of the NH group in 7 was clearly evidenced by a singlet
at 4.46 ppm, while the presence of a doublet at 194.7 ppm in
the 13C{1H} NMR spectrum (1JYC = 40.3 Hz) was consistent
with the sp2-carbon atom of the benzothiophene ring still
covalently bound to the yttrium center.
The X-ray diffraction study of 8 revealed that it crystallizes as
a solvate (8·C6H6). The yttrium atom in 8 is covalently bound
by the amido nitrogen of the amidopyridinate ligand, the sp2
carbon of the thiophenyl ring, and a nitrogen atom of the
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anilido fragment (Figure 2). Moreover, yttrium is coordinated
by one nitrogen from the pyridyl central unit and two nitrogens
from the ancillary pyridine molecules. The coordination
number of yttrium in 8 is 6, with a distorted-square-bipyramidal
coordination geometry. The Y−C bond length in 8 (2.551(3)
Å) is slightly longer in comparison to that measured in related
heteroaryl−hydrido complexes (2.514(3) Å).4b The distances
between yttrium and nitrogen atoms of the amidopyridinate
ligand (Y(1)−N(1) = 2.253(2) Å, Y(1)−N(2) = 2.475(2) Å)
are close to those previously reported for related six-
coordinated yttrium complexes4a,b (2.202(1)−2.254(1) and
2.420(1)−2.462(2) Å, respectively). The amidopyridinate
ligand is not planar, showing a maximum deviation of atoms
from the eight-membered metallacycle of 0.343(2) Å (C(13)).
The angle between the planes containing the pyridine central
unit and the benzothiophenyl fragments is 13.6°. The measured
covalent Y−N(5) bond distance is 2.293(2) Å.
Figure 3. Molecular structure of complex 9 with 30% probability
ellipsoids. The Pr substituents of the aminopyridinate ligand, the
When a yellow solution of 7 in toluene was kept at room
temperature for 1 week, the precipitation of orange crystals
took place. Notably, an X-ray diffraction study of the isolated
crystals revealed the formation of a bis(anilido) yttrium
compound 9 supported by the tridentate amidopyridinate
ligand (Scheme 3). Isolation of 9 was continued after the
i
aniline ligands, and hydrogen atoms are omitted for clarity. Selected
distances (Å) and angles (deg): Y(1)−N(1) = 2.177(3), Y(1)−N(2) =
2.475(2), Y(1)−N(3) = 2.236(3), Y(1)−N(4) = 2.231(2), Y(1)−S(1)
= 3.0755(9); N(1)−Y(1)−N(2) = 70.70(9), N(1)−Y(1)−S(1) =
132.79(7), N(2)−Y(1)−S(1) = 65.26(6), N(3)−Y(1)−N(4) =
116.36(9).
Scheme 3. Synthesis of the Bis-Anilido Complex 9
distance in 9 significantly exceeds the sum of the covalent radii
of these atoms (2.82 Å); nevertheless, it still lies below the sum
of van der Waals radii (4.25 Å) (Y, Rcoval = 1.68, RVdW = 2.4; S,
R
coval = 1.14, RVdW = 1.85).22 It is worth noting that complexes
containing Y−S coordination bonds are still rather rare. The
bond lengths between yttrium and anilido nitrogens (Y−
N(3,4) = 2.231(2) and 2.236(3) Å, respectively) slightly exceed
those measured in 6 (2.203(1) Å) but are somewhat longer
than those found in 8 (2.293(2) Å). The dihedral angle
between the pyridinate and benzothiophenyl fragments (29.8°)
is significantly larger in comparison to that measured in 8
(13.6°) as well as those found in other related yttrium
complexes.4b
The generation of a bis(anilido) species, in pursuit of the
synthesis of rare-earth terminal imido complexes, has been
already documented.17 Complex 9 may result from a hydrogen
abstraction by a transient terminal imido complex followed by a
ligand redistribution reaction. Unfortunately, all our attempts to
isolate the imido intermediate still failed. The source for
hydrogen abstraction also remains unclear, but THF seems to
be a plausible candidate for that role. The intermolecular
protonolysis and ligand redistribution reactions can be also
evoked as possible routes of formation of 9.
All these data taken together make reasonable the
assumption of the crucial role played by the nature of the
heterocyclic group at the amidopyridinate ligand in controlling/
driving the evolution path of the intermediate terminal imido
complexes. While in the case of a benzofuryl-containing system
a concerted intramolecular C−H bond activation and ring-
opening reaction occur, when a benzothiophene-containing
analogue (having similar steric and electronic properties) is
employed, the reaction pathway changes dramatically: no
heterocycle ring opening is observed, while protonolysis and
ligand redistribution reactions take place. Such a different
behavior could originate in the contribution of either different
Lewis base softness/hardness of the oxygen and the sulfur
atoms or by a substantial difference of in terms of energies of
Y−O and Y−S covalent bonds (Y−O, 692.5−719.0 kJ/mol; Y−
separation of the first batch of crystals ,and an overall 30% yield
of 9 were collected from the mother liquor after maintaining
the solution for 2 weeks at room temperature.
Complex 9 crystallizes as a solvate with one molecule of
toluene per unit. In 9 the yttrium atom is coordinated by a
monoanionic tridentate amidopyridinate ligand, the latter
resulting from the intramolecular protonolysis of the Y−
C(heteroaryl) bond on precursor 7 (Scheme 3 and Figure 3).
The Y−C(heteroaryl) bond protonolysis allows the sulfur
atom to coordinate the yttrium center. As Figure 3 shows, the
coordination number of yttrium is 5. Unlike the case in
complex 7, the amidopyridinate ligand in 9 is bound to the
yttrium center via one covalent Y−N bond, while both sulfur
and nitrogen atoms form coordinative bonds with the metal
center. The length of the covalent Y−N(1) bond (2.177(3) Å)
in 9 is slightly shorter than that measured in related six-
coordinated yttrium complexes stabilized by dianionic
amidopyridinate ligands (2.206(2)−2.254(2) Å),4 but it falls
into the range of values reported for five-coordinate yttrium
amides.10 The length of the coordination bond between yttrium
and the nitrogen atom of the amidopyridinate ligand (Y(1)−
N(2) = 2.475(2) Å) is close to those previously reported for
related six-coordinated yttrium complexes (2.420(1)−2.462(2)
Å).4a,b Finally, the Y−S bond distance in 9 (3.0755(9) Å) is
much longer in comparison to the distances measured in five-
coordinated yttrium complexes with either chelating bis-
(thiophosphinic amide) (2.7910(6) Å)16a or bis(thiophosphinic
amidate) (2.718(1) and 2.741(1) Å) ligands.16b The Y−S
D
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S, 528.4 10.5 kJ/mol).15 In our opinion, the formation of a
strong covalent Y−O bond is largely responsible for the ring-
opening reaction occurring at the benzofuryl moiety and
leading to complex 6.
As an additional proof of the relevant contribution played by
the ligand’s heteroaromatic group on the transformation/
rearrangement path of the rare-earth terminal imido
intermediates, we finally investigated the reaction of 2,6-
diisopropylaniline with complex 3 (containing an α-ethyl-
thiophene substituent at the 6-position of the pyridine ring; see
Chart 1). The NMR-tube reaction of 3 with an equimolar
amount of 2,6-diisopropylaniline in C6D6 at room temperature
showed the occurrence of a selective protonolysis of the Y−
C(alkyl) bond exclusively while the Y−C(thien-2-yl) bond
remained untouched (as confirmed by a clear doublet at 202.1
ppm (d, 1JYC = 36.2 Hz) in the 13C{1H} NMR spectrum). The
reaction takes place with the simultaneous release of SiMe4 and
formation of the anilido species 10. A similar reactivity between
2,6-diisopropylaniline and yttrium complexes containing both
Y−C(alkyl) and Y−C(aryl) bonds has been recently
documented by Chen et al.5 Complex 10 was characterized
by spectroscopic analysis and microanalysis. Unfortunately, all
attempts to obtain suitable crystals of 10 for X-ray analysis
failed. However, the treatment of 10 with an excess of pyridine
and the subsequent recrystallization from toluene allowed us to
obtain high-quality crystals of the pyridine adduct 11 (Scheme
4).
Figure 4. Molecular structure of complex 11 with 30% probability
ellipsoids; the Pr substituents in amidopyridinate and aniline ligands,
i
the CH groups of the Py molecules, and hydrogen atoms are omitted
for clarity. Selected distances (Å) and angles (deg): Y(1)−N(1) =
2.247(2), Y(1)−N(5) = 2.289(2), Y(1)−N(2) = 2.452(2), Y(1)−
N(3) = 2.496(2), Y(1)−N(4) = 2.495(2), Y(1)−C(22) = 2.506(2);
N(1)−Y(1)−N(2) = 68.17(7), N(1)−Y(1)−C(2) = 137.13(8),
N(3)−Y(1)−N(4) = 161.97(7).
Å) in 11 is slightly longer than those measured in both the alkyl
precursor 3 (2.482(2) Å)4b and in the related yttrium
monoalkyl thien-2-yl species, the latter featuring an analogue
intramolecular C−H bond activation at the β position of the
thienyl moiety (2.423(3) Å).19 The distance between the Y
center and the anilido nitrogen atom (2.289(2) Å) is slightly
longer than that measured for the amido Y−N bond, the latter
being similar to those observed in related structures.17a,20 The
dihedral angle between the pyridinate and thiophenyl fragments
is 1.7°, and it is significantly lower than that observed in 8.
For all compounds (6, 8, 9, and 11) featuring anilido
fragments, the observed bond distances between the Y atom
and the centers of N−H bonds (2.27−2.37 Å) together with
the measured Y−N−H angles (85.4−101.2°) suggest the
presence of agostic Y−NH bond interactions.23
Scheme 4. Synthesis of the Anilido Complexes 10 and 11
It is worth noting that complex 10 is distinguished by its
extraordinary stability. Unlike complexes 4 and 7, neither
intramolecular protonolysis of Y−C(thien-2-yl) bond by the
anilido NH group nor a ligand redistribution reaction takes
place both at room temperature (for prolonged timesup to 1
month) and upon heating at 80 °C for several hours. No
decomposition/rearrangement takes place even after heating at
100 °C for 3 h. Such a result demonstrates, once more, how
small modifications on the ligand framework can change the
reactivity at the metal center remarkably, driving the reaction
course toward different (and differently stable) organo-
lanthanide species.
An X-ray diffraction study of 11 (Figure 4) revealed that the
coordination environment at the yttrium center was set up by
two nitrogen atoms and one carbon atom from the dianionic
tridentate amidopyridinate ligand, one nitrogen atom from the
monoanionic anilido group, and two nitrogen atoms from the
two pyridine molecules. The coordination number of yttrium in
11 is 6. The coordination environment around the yttrium ion
can be considered as a distorted octahedron where the
amidopyridinate and anilido ligands are located in the
equatorial plane, while two pyridine molecules occupy the
apical positions. Complex 11 crystallizes as a solvate with one
toluene molecule and contains two crystallographically
independent molecules in the asymmetric unit. Both molecules
have similar parameters, and therefore only one of them will be
discussed.
CONCLUSION
■
In this paper we have described the reactions of alkyl−
heteroaryl complexes 1−3, containing Y−C(sp3, alkyl) and Y−
C(sp2, heteroaryl) bonds, with an equimolar amount of 2,6-
diisopropylaniline. For all scrutinized systems the protonolysis
of the Y−C(alkyl) bond takes place selectively at room
temperature, leading to the formation of the corresponding
anilido−heteroaryl species which keep the Y−C(sp2, hetero-
The coordination mode of the amidopyridinate ligand in 11
is similar to that observed in the parent alkyl species.4b The Y−
amidopyridinate fragment is planar (the maximum deviation
from the plane is 0.047(1) Å). The Y−C(22) bond (2.506(2)
E
dx.doi.org/10.1021/om400099z | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
solution of trimethylaluminum (TMA; 1.86 mL, 3.73 mmol). The
reaction mixture was stirred at room temperature for 12 h and then
was quenched with 20 mL of water. The aqueous phase was extracted
with 3 × 15 mL of AcOEt, and the combined organic layers were dried
over Na2SO4. Removal of the solvent under reduced pressure gave the
amidopyridinate ligand as a crude pale yellow solid. The ligand was
purified by crystallization from hot MeOH, by cooling the resulting
solution to −20 °C overnight to afford white crystals in 89% yield
aryl) bonds untouched. Notably, both the stability of the
anilido−heteroaryl derivatives and their potential transforma-
tion/rearrangement paths remarkably differentiate one from the
other upon heating the complexes at elevated temperatures. In
this regard, we have demonstrated how the nature of the
heteroaryl framework attached to the 6-position of the pyridine
ring can strongly influence both the reaction course and the
complex stability. Thus, in the case of the anilido complex 4 a
furyl ring opening takes place, leading to the unprecedented
amido−yne−phenolate derivative 6. Supposedly, complex 6
results from an intramolecular protonolysis of the Y−
C(heteroaryl) bond (promoted by the residual proton of the
NH anilido group), formation of the terminal imido complex,
and its subsequent and rapid intramolecular hydrogen
abstraction at the β-position of the heteroaromatic moiety.
For the analogous complex 7, containing a benzothiopheyl
fragment with stereoelectronic properties similar to those of 4,
no heteroaryl ring opening takes place. It seems reasonable to
invoke the formation of a strong covalent Y−O bond as the
main driving force toward the generation of 6. Unlike 4, a
solution of complex 7 undergoes slow Y−C(heteroaryl) bond
protonolysis, leading to the formation of a complex stabilized
by a monoanionic amidopyridinate ligand featuring a
coordinative intramolecular Y−S interaction. Finally, the
anilido−heteroaryl complex 10 featuring an α-ethylthiophenyl
group turns out to be extraordinarily inert, since no reaction/
rearrangement takes place even after prolonged heating at high
temperatures (up to 100 °C). Further studies are currently
ongoing in our laboratories with the aim at exploring the role of
both the multidentate ancillary ligands and the rare-earth metal
ion sizes on the formation and stability of terminal imido
species.
1
3
(0.95 g). H NMR (200 MHz, CD2Cl2, 293 K): 1.12 (12H, d, JHH
=
6.8 Hz, CH(CH3)); 1.52 (6H, s, C(CH3)2); 3.38 (2H, sept, 3JHH = 6.8
Hz, CH(CH3)); 4.40 (1H, bs, NH); 7.10 (3H, m, Ar); 7.40−7.35 (2H,
m, Ar); 7.51 (1H, m, Ar); 7.92−7.75 (5H, Ar). 13C{1H} NMR (50
MHz, CD2Cl2, 293 K): 23.9 (CH(CH3)2); 28.3 (CH(CH3)2); 28.9
(C(CH3)2); 59.3 (C(CH3)2); 117.0 (Ar); 118.4 (Ar); 120.7 (Ar);
122.4 (Ar); 123.0 (Ar); 124.0 (Ar); 124.0 (Ar); 124.4 (Ar); 124.5
(Ar); 124.9 (Ar); 137.1 (Ar); 140.3 (Ar); 140.7 (Ar); 145.7 (Ar);
146.8 (Ar); 150.8 (Ar); 168.1 (Ar). IR (KBr): 573 (m); 645 (s); 713
(s); 742 (s); 750 (s); 781 (m); 805 (s); 829 (s); 838 (m); 860 (m);
897 (w); 931 (m); 938 (m); 995 (s); 1089 (s); 1124 (s); 1154 (s);
1180 (m); 1203 (s); 1248 (s); 1256 (s); 1330 (m); 1359 (s); 1240
(s); 1440 (s); 1528 (m); 1570 (s); 1583 (s); 1645 (w); 3054 (w);
3343 (s) cm−1. Anal. Calcd for C28H32N2S: C, 78.46; H, 7.52; N, 6.54;
S, 7.48. Found: C, 79.01; H, 7.58; N, 6.50; S, 6.91.
Synthesis of [NNSBzTh]YCH2SiMe3(THF)2 (2). To a solution of
Y(CH2SiMe3)3(THF)2 (0.4284 g, 0.87 mmol) in hexane (25 mL) was
added a solution of N2HBTh (0.3526 g, 0.82 mmol) in hexane (15 mL)
at 0 °C, and the reaction mixture was stirred for 0.5 h. The product
crystallized from the reaction mixture as a pale yellow microcrystalline
1
solid and was isolated in a yield of 91% (0.5475 g). H NMR (400
MHz, C6D6, 293 K): −0.62 (2H, d, 2JYH = 2.6 Hz, YCH2); 0.18 (9H, s,
SiMe3); 0.94 (8H, m, THF); 1.28 (6H, s, C(CH3)2); 1.31 (6H, d, 3JHH
3
= 6.8 Hz, CH3(i-Pr)); 1.35 (6H, d, JHH = 6.8 Hz, CH3(i-Pr)); 3.62
(8H, m, THF); 3.80 (2H, sept, 3JHH = 6.8 Hz, CH(CH3)2); 6.62 (1H,
d, 3JHH = 7.9 Hz, m-Py); 7.07−7.15 (3H, m, p-Py, p-NPh, BTh); 7.30
(1H, d, 3JHH = 7.6 Hz, m-Py); 7.31 (1H, d, 3JHH = 6.0 Hz, BTh); 7.34−
7.37 (2H, m, m-NPh); 7.95 (1H, d, 3JHH = 7.9 Hz, BTh); 8.60 (1H, d,
3JHH = 7.8 Hz, BTh). 13C{1H} NMR (100 MHz, C6D6, 293 K): 4.3
(SiMe3); 23.7 (CH3(i-Pr)); 24.4 (THF); 27.8 (CH(i-Pr)); 28.3-
EXPERIMENTAL SECTION
■
2
(CH3(i-Pr)); 31.2 (C(CH3)2); 31.6 (YCH2); 69.2 (d, JYC = 2.3 Hz,
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 was purchased from
Acros and was dried over CaH2 and molecular sieves. Anhydrous
C(CH3)2); 70.0 (THF); 116.0 (m-Py); 117.6 (m-Py); 122.1 (Ar);
123.9 (Ar); 124.0 (Ar); 124.1 (Ar); 124.6 (Ar); 129.7 (Ar); 139.1 (p-
Py); 143.7 (d, 3JYC = 1.8 Hz, YCCCS); 143.8 (d, 2JYC = 3.1 Hz, YCC);
144.2 (Ar); 149.7 (Ar); 152.0 (d, 2JYC = 2.4 Hz, Ar); 158.5 (Ar); 174.8
1
(Ar); 195.9 (d, JYC = 37.2 Hz, Y−C). IR (KBr): 479 (w); 574 (w);
669 (w); 724 (s); 740 (s); 805 (s); 838 (m); 862 (s); 934 (w); 970
(w); 1026 (m); 1073 (w); 1090 (m); 1125 (m); 1159 (w); 1178 (m);
1226 (w); 1234 (w); 1247 (w); 1307 (m); 1530 (w); 1570 (s); 1590
(m) cm−1. Anal. Calcd for C40H57N2O2SSiY: C, 64.32; H, 7.69; N,
3.75; Y, 11.90. Found: C, 64.51; H, 7.64; N, 3.54; Y, 11.92.
24
(Me3SiCH2)3Y(THF)2 and compounds 1 and 34 were prepared
according to literature procedures. The imino precursor (N2BTh) to the
benzothiophene-containing aminopyridinate ligand (N2HBTh) was
prepared according to similar procedures reported in the literature.25
All other commercially available chemicals were used after the
appropriate purifications. NMR spectra were recorded with either a
Bruker DPX 200 or a Bruker Avance DRX-400 spectrometer in CDCl3
or C6D6 at 25 °C, unless otherwise stated. Chemical shifts for 1H and
13C{1H} NMR spectra were referenced internally to the residual
solvent resonances and are reported in ppm relative to TMS. IR
spectra were recorded as Nujol mulls with a Bruker Vertex 70
instrument. Raman spectra were recorded with the RAM II accessory
module coupled to the Bruker Vertex 70, equipped with a InGaAs
detector and an Nd:YAG laser source (1064 nm) for sample excitation
at a power of ∼450 mW and resolution of 4 cm−1. All of the Raman
spectra were recorded in the wavenumber range 50−3500 cm−1.
Lanthanide metal analyses were carried out by complexometric
titrations. The C, H, N elemental analyses were performed in the
microanalytical laboratory of the G. A. Razuvaev Institute of
Organometallic Chemistry.
Synthesis of [NNOBzFur]YNH-2,6-iPr2C6H3(THF)2 (4). A solution
of 2,6-diisopropylaniline (0.0517 g, 0.29 mmol) in hexane (10 mL)
was added to a solution of 1 (0.2132 g, 0.29 mmol) in a hexane/
toluene mixture (20 mL, 4/1) at room temperature, and the reaction
mixture was stirred for 0.5 h. The reaction mixture changed from
yellow to red. The reaction mixture was kept at −18 °C overnight.
Complex 4 was isolated as a yellow-orange microcrystalline solid in
1
76% yield (0.182 g). H NMR (400 MHz, C6D6, 293 K): 1.16−1.18
3
(14H, m, CH3(i-Pr), THF); 1.33 (6H, d, JHH = 6.7 Hz, CH3(i-Pr));
3
1.38 (12H, d, JHH = 6.5 Hz, CH3(i-Pr)); 1.23 (6H, s, C(CH3)2);
2.71−2.84 (2H, compl m, CH(i-Pr)); 3.56 (8H, m, THF); 3.76 (2H,
sept, 3JHH = 6.5 Hz, CH(i-Pr)); 4.13 (1H, s, NH anilido); 6.63 (1H, m,
m-Py); 6.98−7.18 (6H, m, o-,p-NPh, o-,p-anilido); 7.19−7.22 (1H,
m-,p-Py); 7.25 (1H, m, Ph); 7.32 (1H, m, Ph); 7.68 (1H, m, Ph); 8.27
(1H, m, Ph); 7.66 (1H, m, m-Py). 13C{1H} NMR (100 MHz, C6D6,
293K): 24.1 (CH3(i-Pr)); 24.9 (CH3(i-Pr)); 26.3 (THF); 27.4
(CH3(i-Pr)); 27.9 (CH(i-Pr)); 31.1 (C(CH3)2); 68.3 (C(CH3)2);
68.6 (THF); 113.9 (Ar); 114.4 (m-Py); 117.5 (m-Py); 121.5 (Ar);
122.5 (Ar, anilido); 122.8 (Ar, anilido); 124.6 (Ar, anilido); 124.2
(Ar); 127.1 (Ar); 132.8 (Ar, anilido); 133.4 (Ar, anilido); 139.0 (p-
Py); 140.4 (Ar); 148.4 (Ar, anilido); 149.0 (Ar, anilido); 151.8 (Ar);
Synthesis of the Benzothiophene-Containing Aminopyridi-
BTh
nate Ligand (N2HBzTh). A solution of the iminopyridine ligand N2
(1.00 g, 2.49 mmol) in dry and degassed toluene (20 mL) was cooled
to 0 °C in an ice bath and treated dropwise with a 2.0 M toluene
F
dx.doi.org/10.1021/om400099z | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
156.6 (Ap); 157.2 (d, JYC = 40.9 Hz, Y−C); 161.0 (Ar); 175.1 (Ar).
IR (KBr): 467 (w); 484 (w); 514 (w); 552 (w); 570 (w); 617 (w);
635 (w); 649 (w); 678 (w); 695 (w); 743 (s); 775 (w); 799 (m); 810
(m); 840 (m); 852 (m); 880 (m); 894(m); 926 (w); 936 (m); 960
(w); 967 (w); 990 (w); 1007 (w); 1026 (m); 1046 (m); 1084 (m);
1095 (w); 1107 (w); 1122 (m); 1170 (m); 1178 (m); 1197 (w); 1229
(w); 1254 (s); 1303 (w); 1318 (w); 1341 (w); 1363 (w); 1424 (s);
1462 (s); 1506 (w); 1573 (m); 1588 (w); 1601 (w); 3405 (w); 3482
(w) cm−1. Anal. Calcd for C48H64N3O3Y: C, 70.31; H, 7.87; N, 5.12; Y,
10.84. Found: C, 70.42; H, N, 4.75; 7.98; Y, 10.77.
Synthesis of [NNSBzTh]YNH-2,6-iPr2C6H3(py)2 (8). A 0.2516 g
amount (0.30 mmol) of 7 was dissolved in pyridine (4 mL). The
solution was kept at room temperature for 0.5 h, and the volatiles were
removed under vacuum. The orange-yellow solid residue was dissolved
in a minimum volume of toluene, and the solution was slowly
concentrated at ambient temperature. Complex 8 was isolated as
1
orange-yellow crystals in 77% yield (0.1968 g). H NMR (400 MHz,
3
C6D6, 293 K): 0.83 (6H, d, JHH = 6.8 Hz, CH3(i-Pr)); 1.22 (6H, d,
3
3JHH = 7.1 Hz, CH3(i-Pr)); 1.23 (12H, d, JHH = 6.7 Hz, CH3(i-Pr));
1.29 (6H, s, C(CH3)2); 2.87 (2H, sept, 3JHH = 6.5 Hz, CH(i-Pr)); 3.71
Synthesis of [NNCCO]YNH-2,6-iPr2C6H3(THF) (6). A solution
of 2,6-diisopropylaniline (0.0869 g, 0.49 mmol) in hexane (10 mL)
was added to a solution of 1 (0.3582 g, 0.49 mmol) in a hexane/
toluene mixture (30 mL, 4/1) at room temperature, and the reaction
mixture was stirred for 0.5 h and then was heated to 50 °C for 30 h.
The reaction mixture turned from yellow to deep red. The solution
was kept at −18 °C overnight. Complex 6 was isolated as yellow-
3
(2H, sept, JHH = 6.6 Hz, CH(i-Pr)); 4.73 (1H, s, NH anilido); 6.30
(4H, t, 3JHH = 6.3 Hz, Py); 6.60 (2H, t, 3JHH = 7.6 Hz, Py); 6.72 (1H,
3
3
d, JHH = 7.9 Hz, m-Py); 6.87 (1H, t, JHH = 7.3 Hz, p-anilido); 6.99
(1H, dd, 3JHH = 7.8 Hz, 3JHH = 7.9 Hz, m-Ph); 7.09 (1H, dd, 3JHH = 7.9
3
Hz, JHH = 7.8 Hz, m-Ph); 7.12 (1H, m, p-NPh); 7.18−7.22 (3H,
3
compl. m, m-NPh, p-Py); 7.25 (2H, d, JHH = 6.8 Hz, m-Ph); 7.44
(1H, d, 3JHH = 7.7 Hz, m-Py); 7.80 (1H, d, 3JHH = 7.8 Hz, o-Ph); 7.96
1
(1H, d, JHH = 7.9 Hz, p-Ph); 8.62 (4H, s, Py). 13C{1H} NMR (100
3
orange crystals in 54% yield (0.1981 g). H NMR (400 MHz, C6D6,
3
293 K): 1.06−1.18 (10H, m, CH3(i-Pr), THF); 1.27 (12H, d, JHH
=
MHz, C6D6, 293 K): 24.9 (CH3(i-Pr)); 25.0 (CH3(i-Pr)); 26.6
6.7 Hz, CH3(i-Pr)); 1.37−1.50 (6H, broad m, CH3(i-Pr)); 1.98 (6H, s,
C(CH3)2); 2.95−3.63 (7H, compl m, CH(i-Pr), THF); 4.42 (1H,
broad m, CH(i-Pr)); 5.31 (1H, s, NH); 6.50−6.58 (2H, m, m-Py, p-
(CH3(i-Pr)); 27.8 (CH(i-Pr)); 28.4 (CH(i-Pr)); 32.1 (C(CH3)2);
2
67.7 (d, JYC = 2.0 Hz, C(CH3)2); 114.6 (Ar); 115.0 (m-Py); 116.5
(m-Py); 121.8 (Ar); 122.6 (Ar); 122.8 (Ar); 123.3 (Ar)); 123.6 (Py);
3
Ph); 6.60 (2H, t, JHH = 8.3 Hz, m-Ph); 6.74−6.83 (2H, m, p-Py, p-
124.1 (Ar); 124.4 (Ar); 129.8 (Ar); 133.7 (Ar)); 137.2 (Py); 139.9 (p-
3
2
Ph); 7.08−7.15 (6H, m, o-NPh, o-anilido, p-NPh, p-anilido); 7.42
Py); 143.4 (d, JYC = 1.5 Hz, YCCCS); 143.9 (d, JYC = 2.2 Hz,
(1H, dd, JHH = 7.4 Hz, JHH = 1.4 Hz, m-Py). 13C{1H} NMR (100
MHz, C6D6, 293 K): 22.6−24.6 (broad s, Ar, anilido); 24.9 (THF);
25.3−27.0 (broad s, Ar, anilido); 27.0−28.9 (broad s, Ar, anilido); 29.8
3
3
2
YCCS); 148.5 (Ar); 149.9 (Py); 149.9 (Ar); 151.9 (d, JYC = 2.0 Hz,
YCCCS); 152.5 (d, 2JYC = 3.9 Hz, ipso-Ar); 159.2 (Py Ar); 176.1 (Py);
1
199.9 ppm (d, JYC = 34.4 Hz, Y−C). IR (KBr): 556 (w); 626 (m);
3
(broad s, Ar, anilido); 64.7 (d, JYC = 2.6 Hz, Ar); 69.6 (broad s,
675 (m); 683 (m); 703 (s); 728 (w); 748 (s); 798 (m); 807 (m); 842
(m); 884 (w); 952 (w); 1006 (m); 1017 (w); 1038 (s); 1069 (m);
1092 (w); 1109 (w); 1125 (w); 1152 (m); 1179 (m); 1216 (m); 1225
(m); 1259 (s); 1308 (w); 1319 (w); 1324 (s); 1343 (s); 1568 (s);
1590 (s); 1599 (s); 1622 (w); 3455 (w); 3467 (w) cm−1. Anal. Calcd
for C50H58N5SY: C, 70.65; H, 6.88; N, 8.24; Y, 10.46. Found: C, 70.78;
H, 7.14; N, 7.89; Y, 10.51.
THF); 93.4 (Ph-CC); 101.2 (Ph−CC); 115.5 (Ar); 115.8 (Ar); 118.2
(m-Py); 118.7 (Ar); 119.9 (Ar); 122.7 (Ar, anilido); 123.3 (Ar,
anilido); 123.4 (Ar, anilido); 127.9 (Ar); 129.3 (m-Py); 132.3 (Ar,
anilido); 133.0 (Ar, anilido); 137.5 (Ar, anilido); 138.8 (p-Py); 140.5
(Ar); 148.0 (Ar); 151.4 (d, 2JYC = 4.5 Hz, Ar anilido); 171.6 (d, 2JYC
=
3.5 Hz, Ar); 177.3 (Y−O−C). IR (KBr): 569 (w); 605 (w); 743 (s);
806 (s); 850 (m); 935 (m); 1027 (s); 1044 (s); 1096 (s); 1147 (w);
1170 (w); 1193 (w); 1260 (s); 1308 (s); 1323 (m); 1364 (m); 1439
(s); 1564 (m); 1573 (s); 1589 (m); 1618 (m); 2196 (m); 3342 (w);
3404 (w); 3482 (w) cm−1. Anal. Calcd for C44H56N3O2Y: C, 70.67; H,
7.55; N, 5.62; Y, 11.89. Found: C, 70.32; H, 7.61; N, 5.20; Y, 11.79.
Synthesis of [NNSBzTh]YNH-2,6-iPr2C6H3(THF)2 (7). A solution
of 2,6-diisopropylaniline (0.0803 g, 0.45 mmol) in hexane (10 mL)
was added to a solution of 2 (0.3384 g, 0.45 mmol) in a toluene/
hexane mixture (30 mL) at room temperature, and the reaction
mixture was stirred for 0.5 h. The volatiles were removed under
vacuum, and the solid residue was recrystallized from toluene to give
0.2952 g (78% yield) of 7 as a yellow microcrystalline solid. 1H NMR
(400 MHz, C6D6, 293 K): 1.10 (8H, m, THF); 1.17 (6H, d, 3JHH = 6.5
Hz, CH3(i-Pr)); 1.25 (12H, d, 3JHH = 6.6 Hz, CH3(i-Pr) anilido); 1.29
(6H, d, 3JHH = 6.8 Hz, CH3(i-Pr)); 1.36 (6H, s, C(CH3)2); 2.96 (2H,
sept, 3JHH = 6.8 Hz, CH(i-Pr) anilido); 3.55 (8H, m, THF); 3.73 (2H,
sept, 3JHH = 6.82 Hz, CH(i-Pr)); 4.52 (1H, s, NH anilido); 6.63 (1H,
d, 3JHH = 7.9 Hz, m-Py); 6.81 (1H, t, 3JHH = 7.5 Hz, p-anilido); 7.07−
7.12 (2H, m, p-Py, m-Ph); 7.16−7.19 (3H, m, p-NPh, m-anilido);
7.21−7.25 (2H, m, m-NPh); 7.33 (2H, d, 3JHH = 7.9 Hz, o-Ph, m-Py);
Synthesis of [NNSBzThH]Y(NH-2,6-iPr2C6H3)2 (9). A solution of 7
(0.2785 g, 0.33 mmol) in a toluene/hexane mixture (5 mL, 3/2) was
kept at room temperature for 2 weeks. Complex 9 slowly formed as
fine bright-orange crystals and was isolated in 30% yield (0.0864 g). 1H
NMR (400 MHz, C6D6, 293 K): 1.06 (24H, d, 3JHH = 6.7 Hz, CH3(i-
Pr)); 1.28 (6H, d, 3JHH = 6.9 Hz, CH3(i-Pr)); 1.48 (6H, d, 3JHH = 6.9
Hz, CH3(i-Pr)); 1.56 (6H, s, C(CH3)2); 2.66 (4H, sept, 3JHH = 6.4 Hz,
CH(i-Pr)); 3.72 (2H, sept, 3JHH = 6.8 Hz, CH(i-Pr)); 5.01 (2H, s, NH
anilido); 6.79 (3H, t, 3JHH = 7.6 Hz, p-Ph, m-Py); 6.84 (1H, dd, 3JHH
=
7.30 Hz, 3JHH = 7.10 Hz, Ar); 6.91 (1H, dd, 3JHH = 7.7 Hz, 3JHH = 7.6
3
Hz, m-Py); 6.98 (3H, compl m, p-Py); 7.07(4H, d, JHH = 7.6 Hz, m-
Ph); 7.09−7.14 (2H, compl m, p-NPh); 7.21 (2H, d, 3JHH = 7.5 Hz, m-
3
NPh); 7.37 (1H, d, JHH = 8.0 Hz, Ar). 13C{1H} NMR (100 MHz,
C6D6, 293 K): 23.1 (CH3(i-Pr)); 24.3 (CH3(i-Pr)); 26.4 (CH3(i-Pr));
28.5 (CH(i-Pr)); 30.3 (CH(i-Pr)); 32.6 (C(CH3)2); 63.9 (d, 2JYC = 2.1
Hz, C(CH3)2); 1154.0 (Ar); 118.6 (m-Py); 119.7 (m-Py); 122.5 (Ar);
123.2 (Ar); 123.8 (Ar); 124.6 (Ar); 126.9 (Ar); 127.0 (Ar); 132.8
(Ar); 137.0 (Ar); 139.3 (Ar);139.7 (Ar); 140.4 (Ar); 141.2 (Ar); 147.6
(Ar); 150.1 (Ar); 152.0 (d, 2JYC = 4.1 Hz, ipso-anilido); 178.6 (Ar). IR
(KBr): 464 (m); 515 (w); 537 (w); 557 (w); 695 (s); 728 (s); 747
(s); 794 (m); 809 (m); 841 (m); 866 (w); 881 (w); 891 (w); 960 (w);
1007 (w); 1036 (m); 1079 (w); 1096 (m); 1122 (w); 1148 (w); 1181
(m); 1217 (w); 1230 (w); 1247 (w); 1263 (s); 1304 (w); 1340 (w);
1423 (s); 1461 (s); 1495 (w); 1563 (w); 1571 (m); 1588 (s); 3356
(w) cm−1. Anal. Calcd for C52H67N4SY: C, 71.86; H, 7.77; N, 6.44; Y,
10.23. Found: C, 71.84; H, 7.80; N, 6.75; Y, 10.31.
7.96 (1H, d, 3JHH = 7.5 Hz, o-Ph); 8.22 (1H, d, JHH = 7.8 Hz, p-Ph).
3
13C{1H} NMR (100 MHz, C6D6, 292 K): 24.0 (CH3(i-Pr) anilido);
24.4 (CH3(i-Pr)); 24.9 (THF); 27.0 (CH3(i-Pr)); 27.8 (CH(i-Pr));
29.1 (CH(i-Pr) anilido); 31.8 (C(CH3)2); 67.5 (C(CH3)2); 69.4
(THF); 114.7 (anilido); 116.3 (m-Py); 116.6 (m-Py); 122.2, (Ar);
122.5 (Ar); 122.6 (Ar); 123.3 (Ar); 123.6 (Ar); 123.9 (Ar); 129.6
(Ar); 133.1 (Ar); 139.6 (p-Py); 143.5 (Ar); 145.6 (Ar); 147.5 (Ar);
149.1 (Ar); 152.1 (Ar); 152.4 (Ar); 158.4 (Ar); 175.5 (Ar); 194.6 ppm
(d, 1JYC = 40.4 Hz, Y−C). IR (KBr): 479 (w); 519 (w); 555 (w); 644
(w); 727 (m); 743 (s); 805 (s); 839 (m); 846 (w); 883 (m); 913 (w);
931 (w); 962 (w); 944 (w); 1027 (w); 1042 (w); 1074 (w); 1096 (w);
1124 (w); 1156 (w); 1181(m); 1200 (w); 1246 (s); 1257 (s); 1302
(w); 1321 (w); 1363 (m); 1425 (s); 1445 (s); 1528 (w); 1571 (s);
1588 (s); 1621 (w); 3342 (w); 3354 (w); 3473 (w) cm−1. Anal. Calcd
for C48H64N3O2SY: C, 68.96; H, N, 5.02; 7.72; Y, 10.63. Found: C,
69.01; H, 7.75; N, 4.69; Y, 10.72.
Synthesis of [NNSEtTh]YNH-2,6-iPr2C6H3(py)2 (11). A solution of
2,6-diisopropylaniline (0.0812 g, 0.46 mmol) in toluene (10 mL) was
added to a solution of 3 (0.3320 g, 0.46 mmol) in toluene (30 mL) at
room temperature, and the reaction mixture was stirred for 0.5 h. The
volatiles were removed under vacuum, and the solid residue was
treated with pyridine. The resulting orange oil was dried under vacuum
for 0.5 h and was dissolved in toluene. Slow concentration of the
resulting solution at ambient temperature afforded crystals of 11 in
64% yield (0.2427 g). 1H NMR (400 MHz, C6D6, 293 K): 0.78 (12H,
3
3
broad d, JHH = 6.2 Hz, CH3(i-Pr)); 1.06 (3H, t, JHH = 7.4 Hz, Et-
G
dx.doi.org/10.1021/om400099z | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 1. Crystallographic Data and Structure Refinement Details for Complexes 6, 8, 9, and 11
6
8
9
11
empirical formula
formula wt
cryst syst
space group
a, Å
C51H64N3O2Y
839.96
C56H64N5SY
928.09
C55.50H71N4SY
915.13
C55H68N5SY
920.11
triclinic
orthorhombic
Pbca
monoclinic
P21/c
monoclinic
P21/c
P1
̅
10.0359(6)
11.6546(8)
20.5907(13)
95.8550(10)
90.2040(10)
112.8730(10)
2205.0(2)
2
10.51965(15)
19.8913(4)
47.7557(7)
90
21.976(2)
13.4831(13)
17.1832(17)
90
16.9665(3)
19.4635(3)
30.0634(4)
90
b, Å
c, Å
α, deg
β, deg
90
104.695(2)
90
90.1406(13)
90
γ, deg
V, Å3
90
9992.9(3)
8
4924.9(8)
4
9927.7(3)
8
Z
Pcalcd (g/cm3)
1.265
1.234
1.234
1.231
abs coeff (mm−1
)
1.365
1.250
1.266
1.257
F(000)
892
3920
1948
3904
cryst size, mm
2θ, deg
0.55 × 0.22 × 0.12
52
0.40 × 0.30 × 0.10
60
0.28 × 0.18 × 0.12
52
0.40 × 0.40 × 0.40
60
index ranges
−12 ≤ h ≤ 12
−12 ≤ k ≤14
−23 ≤ l ≤ 25
10883
−14 ≤ h ≤ 14
−27 ≤ k ≤ 27
−67 ≤ l ≤ 67
184929
−27 ≤ h ≤ 27
−16 ≤ k ≤ 16
−21 ≤ l ≤ 21
41090
−23 ≤ h ≤ 23
−27 ≤ k ≤ 27
−42 ≤ l ≤ 42
203301
no. of rflns collected
no. of indep rflns (Rint)
completeness to θ, %
max/min transmission
no. of data/restraints/params
GOF on F2
8215 (0.0226)
94.6
14479 (0.1038)
99.3
9646 (0.1332)
99.6
28866 (0.1638)
99.7
0.8533/0.5206
8215/4/532
1.017
0.8852/0.6347
14479/0/582
1.249
0.8629/0.7181
9646/46/567
0.982
0.6332/0.6332
28866/4/1146
0.964
final R index (I > 2σ(I))
R index (all data)
largest diff in peak/hole, e/Å3
0.0423
0.0748
0.0692
0.0677
0.0978
0.1270
0.1613
0.1695
1.187/−0.924
0.718/−2.452
1.016/−0.544
1.503/−1.316
positions and were refined in the riding model. SADABS28 (6 and 9)
and ABSPACK (CrysAlis Pro)27 (8 and 11) were used to perform
area-detector scaling and absorption corrections. Details of crystallo-
graphic, collection, and refinement data are reported in Table 1.
CCDC files 909588 (6), 909589 (8), 909590 (9), and 909592 (11)
contain the supplementary crystallographic data for this paper. These
data can be obtained free of charge from the Cambridge Crystallo-
graphic Data Centre via ccdc.cam.ac.uk/data_request/cif.
3
CH3,); 1.17 (12H, broad d, JHH = 6.5 Hz, CH3(i-Pr)); 1.36 (6H, s,
3
3
C(CH3)2); 2.62 (2H, q, JHH = 7.4 Hz, Et-CH2); 3.62 (4H, sept, JHH
= 6.5 Hz, CH(i-Pr)); 4.62 (1H, s, NH); 6.25 (4H, m, Py); 6.59, (2H,
3
m, Py); 6.76, (1H, d, 3JHH = 7.9 Hz, m-CH Py); 6.91 (1H, JHH = 7.4
Hz, p-Ph); 7.05 (1H, s, Ar); 7.19−7.30 (4H, compl m, p-Py, m- and p-
NPh); 7.30 (2H, d, 3JHH = 7.4 Hz, m-Ph); 7.40 (1H, d, 3JHH = 7.8 Hz,
m-Py); 8.59 (4H, m, Py). 13C{1H} NMR (100 MHz, C6D6, 293 K):
15.7 (CH3(Et)); 23.2 (CH2(Et)); 24.4, (CH3(i-Pr)); 27.7 (CH3(i-
2
Pr)); 28.0 (CH(i-Pr)); 31.8 (C(CH3)2); 69.1 (d, JYC = 2.4 Hz,
C(CH3)2); 114.4 (anilido); 1154.0 (Ar); 115.3, (Ar); 123.3 (Ar);
ASSOCIATED CONTENT
2
■
123.5 (Py); 123.6 (Ar); 124.2 (Ar); 133.4 (Ar); 134.9 (d, JYC = 2.0
S
2
* Supporting Information
Hz, SCCH); 137.5 (Py); 137.5 (Ar); 139.5 (Ar); 143.2 (d, JYC = 2.3
2
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.
Hz, YCCS); 148.6 (Ar); 149.1 (Ar); 149.7 (Py); 152.6 (d, JYC = 3.9
Hz, ipso-anilido), 159.7 (Ar); 175.4 (Ar); 202.1 (d, 1JYC = 36.2 Hz, Y−
C). IR (KBr): 464 (m); 523 (w); 565 (w); 601 (w); 625 (w); 677
(w); 696 (s); 702 (s); 729 (s); 744 (s); 800 (s); 843 (m); 888 (w);
931 (w); 965 (w); 977 (m); 1009 (m); 1030 (s); 1039 (s); 1069 (m);
1096 (m); 1126 (w); 1162 (m); 1180 (m); 1219 (w); 1261 (s); 1303
(w); 1322 (w); 1362 (m); 1425 (m); 1443 (s); 1479 (m); 1496 (m);
1571 (s); 1587 (s); 1600 (m); 1621 (w); 1800 (w); 1859 (w); 1939
(w); 3343 (w); 3406 (w); 3485 (w) cm−1. Anal. Calcd for
C48H60N5SY: C, 69.63; H, 7.30; N, 8.46; Y, 10.74. Found: C, 69.70;
H, 7.34; N, 8.95; Y, 10.78.
AUTHOR INFORMATION
Corresponding Author
*A.A.T.: fax, (+7)8314621497; e-mail, trif@iomc.ras.ru.
Notes
■
The authors declare no competing financial interest.
X-ray Crystallography. The X-ray data were collected on a Smart
Apex diffractometer (for 6 and 9, graphite-monochromated Mo Kα
radiation, ω-scan technique, λ = 0.71073 Å, T = 100(2) K) and a
Agilent Xcalibur E diffractometer (for 8 and 11, graphite-
monochromated Mo Kα radiation, ω-scan technique, λ = 0.71073 Å,
T = 100(2) K). The structures were solved by direct methods and
were refined on F2 using SHELXTL26 (6 and 9) and CrysAlis Pro27 (8
and 11) package. All non-hydrogen atoms and H atoms in NH groups
of anilido fragments were found from Fourier syntheses of electron
density and were refined anisotropically and isotropically for
hydrogens. All other hydrogen atoms were placed in calculated
ACKNOWLEDGMENTS
■
The study was supported by the Ministry of education and
science of Russian Federation, Project No. 8445, the Russian
Foundation for Basic Research (grant 12-03-31865 mol_a), the
Program of the Presidium of the Russian Academy of Science
(RAS), and the RAS Chemistry and Material Science Division.
We also thank the Groupe de Recherche International (GDRI)
“Homogeneous Catalysis for Sustainable Development” for
support.
H
dx.doi.org/10.1021/om400099z | Organometallics XXXX, XXX, XXX−XXX

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Li, X. W. Inorg. Chem. 2009, 48, 6344−6346.
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