(2,5-Bis{[(2,6-diisopropylphenyl)imino]methyl}pyrrolyl)yttrium and -lutetium complexes - Synthesis and structures

Article abstract of DOI:10.1002/ejic.200701238

The reaction of 2,5-bis{[(2,6-diisopropylphenyl)imino]-methyl}pyrrole (dip₂-pyr)H with nBuLi and KH resulted in the lithium compound [(dip₂-pyr)Li] and the potassium compound [(dip₂-pyr)K], respectively. Transmetallation of [(dip₂-pyr)Li] with YCl₃ in thf afforded the ate complex [(dip₂-pyr)YCl ₃Li(thf)₃], in which an additional equivalent of LiCl is coordinated as a four-membered Li-Cl-Y-Cl metallacycle. In contrast, treatment of [(dip₂-pyr)K] with anhydrous yttrium and lutetium trichloride resulted in [(dip₂-pyr)LnCl₂(thf)₂] (Ln = Y, Lu). Obviously, by using the potassium reagent [(dip₂-pyr)K] the formation of ate complexes is inhibited. Reaction of NaC ₅H₅ with [(dip₂-pyr)YCl₃Li(thf) ₃] or [(dip₂-pyr)-YCl₂(thf)₂] afforded the metallocene [(dip₂-pyr)Y(η⁵-C ₅H₅)₂]. A significant difference in reactivity between the compounds [(dip₂-pyr)YCl₃Li(thf)₃] and [(dip₂-pyr)YCl₂(thf)₂] could not be observed. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200701238

FULL PAPER
DOI: 10.1002/ejic.200701238
(2,5-Bis{[(2,6-diisopropylphenyl)imino]methyl}pyrrolyl)yttrium and -lutetium
Complexes – Synthesis and Structures
Nils Meyer,[a] Magdalena Kuzdrowska,[a] and Peter W. Roesky*[a]
Dedicated to Prof. Dr. Dr.hc.mult. Wolfgang A. Herrmann on the occasion of his 60th birthday
Keywords: Lutetium / N ligands / Potassium / Pyrrole / Yttrium
The reaction of 2,5-bis{[(2,6-diisopropylphenyl)imino]-
methyl}pyrrole (dip2-pyr)H with nBuLi and KH resulted in
= Y, Lu). Obviously, by using the potassium reagent [(dip2-
pyr)K] the formation of “ate complexes” is inhibited. Reac-
the lithium compound [(dip2-pyr)Li] and the potassium com- tion of NaC5H5 with [(dip2-pyr)YCl3Li(thf)3] or [(dip2-pyr)-
pound [(dip2-pyr)K], respectively. Transmetallation of [(dip2-
pyr)Li] with YCl3 in thf afforded the “ate complex” [(dip2-
pyr)YCl3Li(thf)3], in which an additional equivalent of LiCl is
coordinated as a four-membered Li–Cl–Y–Cl metallacycle. In
contrast, treatment of [(dip2-pyr)K] with anhydrous yttrium
and lutetium trichloride resulted in [(dip2-pyr)LnCl2(thf)2] (Ln
YCl2(thf)2] afforded the metallocene [(dip2-pyr)Y(η5-C5H5)2].
A significant difference in reactivity between the compounds
[(dip2-pyr)YCl3Li(thf)3] and [(dip2-pyr)YCl2(thf)2] could not
be observed.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
In this contribution, we report on the synthesis of the
lithium[4] and potassium derivative of 2,5-bis{[(2,6-diisop-
ropylphenyl)imino]methyl}pyrrole (dip2-pyr)H first, fol-
lowed by the reaction of these compounds with YCl3 and
LuCl3. Moreover, the yttrium metallocene derivative [(dip2-
pyr)Y(η5-C5H5)2] is presented.
Introduction
In the last 20 years, much progress has been observed in
the design and application of (amido)metal chemistry of the
early transition metals. In the early stages of this area cyclo-
pentadienyl-analogous amido ligands were studied for com-
parison with and for further investigations of the well-
known cyclopentadienyl moiety. Today, the stable amido–
metal bond is utilized in (amido)metal chemistry to produce
well-defined reaction centers in transition metal complexes.
In this way, the reactivity of the resulting early transition
metal compounds can be specifically tailored to allow appli-
cations in areas such as the activation of small and poorly
reactive molecules, homogeneous catalysis, or organic syn-
thesis.[1,2] In this context, 2-[(arylimino)methyl]pyrrolyl li-
gands were recently introduced into aluminum,[3] group
4,[4–7] iron,[4] cobalt,[4] and nickel[4] chemistry as nitrogen-
based polydentate ancillary ligands. The resulting com-
plexes were used as catalyst precursors for ethylene polyme-
rization. Moreover, some time ago Mashima et al. prepared
tridentate bis(iminomethyl)pyrrolyl ligands and investigated
their reactions with the homoleptic bis(trimethylsilyl)amide
[Y{N(SiMe3)2}3].[8] Homoleptic and heteroleptic pyrrolyl
complexes of yttrium were obtained by the so called “si-
lylamide route”.[9] The heteroleptic complexes were used as
initiators for the polymerization of ε-caprolactone.
Results and Discussion
Alkali Metal Compounds
As reported earlier, (dip2-pyr)H was synthesized by con-
densation of pyrrole-2,5-dicarbaldehyde with 2,6-diisopro-
pylaniline.[5] Treatment of (dip2-pyr)H with nBuLi in tolu-
ene resulted in the lithium compound [(dip2-pyr)Li] (1),
which was described earlier by Bochmann et al.
(Scheme 1).[4] In contrast, the corresponding potassium
compound [(dip2-pyr)K] (2) was not reported previously.
Treatment of (dip2-pyr)H with KH in thf resulted in com-
1
pound 2 (Scheme 1). The H and 13C NMR spectra show
the expected set of signals. The observed chemical shifts are
in good agreement with the lithium salt 1. Only one set of
each signal is observed at δ(1H) = 1.13 and 3.19 ppm for
the isopropyl groups of compound 2 indicating that the 2,6-
diisopropylaniline moieties of the ligand can freely rotate in
solution. By recording the NMR spectra in C6D6 it clearly
can be shown that no thf is coordinated to the potassium
atom. This is somewhat surprising because the reaction was
performed in thf.
[a] Institut für Chemie und Biochemie, Freie Universität Berlin,
Fabeckstraße 34–36, 14195 Berlin, Germany
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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N. Meyer, M. Kuzdrowska, P. W. Roesky
FULL PAPER
numerous metallocenes and ansa-metallocenes known of
the general formula [Ln(η5-C5Me5)2(µ-Cl)2Li(ether)2] and
[Ln{Me2Si(η5-C5Me4)2}(µ-Cl)2Li(ether)2].[11] These struc-
tures contain two bridging chlorido ligands and a lithium
atom bound by two solvate molecules. As expected, the Y–
Cl bonds of compound 3 for the µ-Cl atoms [Y–Cl2
2.663(9) Å and Y–Cl3 2.672(8) Å] are longer then corre-
sponding one for the terminal chlorine atom [Y–Cl1
2.554(2) Å].[12]
Scheme 1.
Rare Earth Complexes
Transmetallation of 1 with anhydrous yttrium trichloride
in thf afforded the “ate complex” [(dip2-pyr)YCl3Li(thf)3]
(3) as crystals in good yields (Scheme 2). The new complex
has been characterized by standard analytical/spectroscopic
techniques, and the solid-state structure was established by
single-crystal X-ray diffraction.
Figure 1. Solid-state structure of 3 with atom-labeling scheme and
hydrogen atoms omitted. Selected bond lengths [Å] and angles [°]:
Y–Cl1 2.554(2), Y–Cl2 2.663(9), Y–Cl3 2.672(8), Y–N1 2.703(9),
Y–N2 2.306(4), Y–N3 2.678(8), Y–O1 2.394(4), Li–Cl2 2.324(14),
Li–Cl3 2.229(14), Li–O2 1.927(2), Li–O3 1.894(15); N1–Y–N2
63.67(14), N1–Y–N3 127.87(13), N1–Y–Cl1 93.14(10), N1–Y–Cl2
74.74(10), N1–Y–Cl3 155.27(10), N1–Y–O1 85.68(14), N2–Y–N3
64.22(12), N2–Y–Cl1 93.60(12), N2–Y–Cl2 137.04(10), N2–Y–Cl3
139.19(10), N2–Y–O1 80.64(14), N3–Y–Cl1 91.6(1), N3–Y–Cl2
154.61(9), N3–Y–Cl3 75.54(9), N3–Y–O1 84.56(14), Y–Cl2–Li
89.66(3), Y–Cl3–Li 89.11(3).
The yttrium atom of compound 3 is heptacoordinated by
the (dip2-pyr)– ligand, two thf molecules, and three chlorine
atoms. Thus, a distorted pentagonal-bipydramidal coordi-
nation polyhedron is formed. In the apices one thf molecule
and one chlorine atom are located. The O1–Y–Cl1 bond
angle is 174.04(10)°. Even the bonds of the imine nitrogen
atoms to the yttrium atom [Y–N1 2.671(3) Å and Y–N3
2.678(3) Å] are significantly longer than that of the pyrrolyl
nitrogen atom to the yttrium atom [Y–N2 2.288(3) Å]. We
consider the (dip2-pyr)– ligand as tridentate. This is in
agreement with the earlier reported compound [(xyl2-pyr)-
Scheme 2.
The 1H and 13C{1H} NMR spectra of compound 3 show Y{N(SiMe3)2}2] {xyl2-pyr = 2,5-bis{[(2,6-dimethylphenyl)-
the expected sets of signals. In contrast to compounds 1 imino]methyl}pyrrolyl; Y–Npyrrolyl 2.288(3) Å, Y–Nimine
and 2, a splitting of the isopropyl CH3 signals into two sets 2.707(3) Å and Y–N3 2.776(3) Å}.[8]
of doublets is observed, which is interpreted as a conse-
In contrast to the reaction described above, transmetalla-
quence of restricted rotation about the N–Cipso bond. Sim- tion of 2 with anhydrous yttrium and lutetium trichloride
ilar observations were made for other 2,6-diisopropylani- in thf at room temperature and crystallization from thf led
line-substituted yttrium complexes, such as [Y{ArN(CH2)3- to the reaction products [(dip2-pyr)LnCl2(thf)2] [Ln = Y
NAr}(thf)2(µ-Cl)2Li(thf)2] (Ar = 2,6-iPr2C6H3).[10]
(4a), Lu (4b)] (Scheme 2). Obviously, by using the potas-
¯
Compound 3 crystallizes in the triclinic space group P1 sium reagent 2, the formation of “ate complexes” is in-
with two molecules of compound 3 and two thf molecules hibited. The multinuclear NMR spectroscopic data is com-
in the unit cell (Figure 1). In this compound an additional parable to that of compound 3. Most significant again is a
equivalent of LiCl is coordinated as a four-membered Li– splitting of the isopropyl CH3 signals into two sets of dou-
Cl–Y–Cl metallacycle. Additionally, two thf molecules are blets at δ(1H) = 1.00 and 1.20 ppm (4a), and 1.00 and
bound to the lithium atom. This kind of LiCl adduct is 1.21 ppm (4b); δ(13C{1H}) = 22.6, 26.7 ppm (4a) and 22.6,
well known in lanthanide chemistry. For example, there are 26.8 ppm (4b).
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Eur. J. Inorg. Chem. 2008, 1475–1479

2,5-Bis{[(2,6-diisopropylphenyl)imino]methyl}pyrrolyl Complexes
The solid-state structure of 4a was investigated by single-
crystal X-ray diffraction (Figure 2). Compound 4a crys-
tallizes in the orthorhombic space group Pbca with eight
molecules in the unit cell. The structure reveals a hepta-
coordination sphere of the ligands around the yttrium atom
resulting in a distorted pentagonal-bipydramidal coordina-
tion polyhedron. In contrast to compound 3, the two chlo-
rine atoms are located in the apices in an almost linear
setup forming a Cl1–Y–Cl2 angle of 172.10(3)°, whereas
the (dip2-pyr)– ligand and two molecules of thf are located
in the plane. The almost planar setup of the latter ligands
is revealed by the sum of the corresponding five angles
(368.22°). The two phenyl rings are oriented perpendicu-
larly to the plane of the pyrrolyl moiety. As observed in
compound 3, the metal–imine nitrogen bonds [Y–N1
2.671(3) Å and Y–N3 2.679(3) Å] are longer than the Y–
Npyrrolyl distance [Y–N2 2.288(3) Å] (Figure 2).
Scheme 3.
molecules of 5 and four molecules of toluene in the unit
cell. As observed in compound 3 and 4a, the metal–imine
nitrogen bonds [Y–N1 2.708(5) Å and Y–N3 2.813(6) Å] of
the (dip2-pyr)– ligand are longer than the Y–Npyrrolyl dis-
tance [Y–N2 2.302(5) Å]. The cyclopentadienyl rings are
bound in the expected η5-coordination mode. The Y–ring
centroid bond lengths of Y–Cg1 2.368(8) Å and Y–Cg2
2.383(2) Å fit well into the range of other cyclopentadienyl
complexes {e.g. [(η5-MeC5H4)2Y(thf){OCN(iPr)2NPh}]:
Y–Cg 2.421(1) Å and 2.391(2) Å;[13] [(η5-C5H5)2Y(C6H4-2-
CH2NMe2)]: Y–Cg 2.39 Å and 2.38 Å} (Figure 3).[14]
Figure 2. Solid-state structure of 4a with atom-labeling scheme and
hydrogen atoms omitted. Selected bond lengths [Å] and angles [°]:
Y–N1 2.671(3), Y–N2 2.288(3), Y–N3 2.679(3), Y–Cl1 2.5915(9),
Y–Cl2 2.5826(9), Y–O1 2.389(2), Y–O2 2.409(3); N1–Y–N2
64.71(9), N1–Y–N3 129.15(9), N1–Y–Cl1 91.00(7), N1–Y–Cl2
93.16(7), N1–Y–O1 76.78(9), N1–Y–O2 154.29(9), N2–Y–N3
64.48(9), N2–Y–Cl1 95.20(7), N2–Y–Cl2 92.58(7), N2–Y–O1
141.28(9), N2–Y–O2 141.01(10), N3–Y–Cl1 91.93(6), N3–Y–Cl2
90.65(6), N3–Y–O1 154.00(9), N3–Y–O2 76.53(9).
Figure 3. Solid-state structure of 5 with atom-labeling scheme and
hydrogen atoms omitted. Selected bond lengths [Å] and angles [°]:
Y–N1 2.708(5), Y–N2 2.302(5), Y–N3 2.813(6), Y–Cg1 2.368(8),
Y–Cg2 2.383(2); N1–Y–N2 64.5(2), N1–Y–N3 124.2(2), N1–Y–Cg1
99.28(11), N1–Y–Cg2 104.60(9), N2–Y–N3 62.4(1), N2–Y–Cg1
128.82(13), N2–Y–Cg2 103.36(10), N3–Y–Cg1 100.62(11), N3–Y–
Cg2 102.89(13) (Cg = ring center).
To learn more about the reactivity of the chlorido com-
plexes, we were interested in synthesizing a cyclopentadienyl
derivative. Reaction of NaC5H5 with 3 or 4a in a 2:1 molar
ratio in thf at room temperature afforded after crystalli-
zation from toluene the metallocene [(dip2-pyr)Y(η5-
C5H5)2] (5) as yellow crystals. We could not observe a sig-
nificant difference in reactivity between compounds 3 and
4a (Scheme 3). As a result of the larger steric bulk of the
Conclusion
We have prepared some new 2,5-bis{[(2,6-diisopro-
cyclopentadienyl ligand, no additional solvent is coordi- pylphenyl)imino]methyl}pyrrolyl compounds of alkaline
nated to the yttrium atom. The new complex has been char- and rare earth metals. The alkaline metal compounds
acterized by standard analytical/spectroscopic techniques. [(dip2-pyr)Li] and [(dip2-pyr)K] could be easily obtained by
The 1H and 13C{1H} NMR spectra of 5 are consistent with a deprotonation of (dip2-pyr)H with the suitable alkaline
a Cs symmetry about the yttrium atom. The resonance of metal reagents nBuLi and KH. By using [(dip2-pyr)Li] and
1
the cyclopentadienyl rings in the H NMR spectrum is ob- [(dip2-pyr)K] in a salt metathesis reaction with YCl3 dif-
served as a sharp singlet (δ = 5.95 ppm). As seen for the ferent products were obtained. Whereas the reaction of
compounds described above, a splitting of the isopropyl [(dip2-pyr)Li] resulted in the “ate complex” [(dip2-pyr)-
1
CH3 signals into two sets of doublets is observed in the H YCl3Li(thf)3], a similar reaction of [(dip2-pyr)K] gave the
NMR spectrum, which is consistent with restricted rotation neutral compound [(dip2-pyr)YCl2(thf)2]. Obviously, by
about the N–Cipso bond. This splitting is not well resolved using the potassium reagent the formation of “ate com-
in the 13C{1H} NMR spectrum.
plexes” is inhibited. Both yttrium compounds are different
The structure of compound 5 was confirmed by single- in their structures, but their reactivities are comparable.
crystal X-ray diffraction in the solid state. Compound 5 Thus, treatment of both compounds with NaC5H5 afforded
crystallizes in the monoclinic space group P21/c with four the organometallic compound [(dip2-pyr)Y(η5-C5H5)2].
Eur. J. Inorg. Chem. 2008, 1475–1479
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N. Meyer, M. Kuzdrowska, P. W. Roesky
FULL PAPER
[(dip2-pyr)LnCl2(thf)2] [Ln = Y (4a), Lu (4b)]. General Procedure:
thf (10 mL) was condensed at –78 °C onto a mixture of LnCl3 and
[(dip2-pyr)K] (2), and the mixture was stirred at ambient tempera-
ture for 18 h. The solution was filtered off and concentrated until
a white residue appeared. The residue was dissolved by heating
and the remaining yellow solution was allowed to stand at ambient
temperature. After 1 d, the product crystallized as yellow crystals.
The crystals were isolated and washed with n-pentane. 4a: YCl3:
0.23 g, 1.2 mmol; [(dip2-pyr)K]: 0.48 g, 1 mmol. X-ray quality crys-
Experimental Section
General Considerations: All manipulations of air-sensitive materials
were performed with the rigorous exclusion of oxygen and moisture
in flame-dried Schlenk-type glassware either on a dual-manifold
Schlenk line, interfaced to a high-vacuum (10–4 Torr) line, or in an
argon-filled MBraun glove box. Tetrahydrofuran was predried with
Na wire and distilled under nitrogen from Na/K benzophenone
ketyl prior to use. Hydrocarbon solvents (toluene and n-pentane)
were distilled under nitrogen from LiAlH4. All solvents for vac-
uum-line manipulations were stored in vacuo over LiAlH4 in re-
sealable flasks. Deuterated solvents were obtained from Chemo-
trade Chemiehandelsgesellschaft mbH (all Ն99 atom-% D) or Eur-
iso-Top GmbH (all Ն99 atom-% D) and were dried, degassed, and
stored in vacuo over Na/K alloy in resealable flasks. NMR spectra
were recorded with a Jeol JNM-LA 400 FT-NMR spectrometer.
Chemical shifts are referenced to internal solvent resonances and
are reported relative to tetramethylsilane. Mass spectra were re-
corded at 70 eV with a Varian MAT 711 instrument. Elemental
analyses were carried out with an Elementar vario EL III. YCl3,[15]
LuCl3,[15] Na(C5H5),[16] and 2,5-bis{[(2,6-diisopropylphenyl)imino]
methyl}pyrrol[17] were prepared according to literature procedures.
[(dip2-pyr)Li] (1):[4] To a solution of 2,5-bis{[(2,6-diisopropyl-
phenyl)imino]methyl}pyrrole (2.00 g, 4.5 mmol) in toluene (40 mL)
a solution of nBuLi in n-hexane (2.5 , 1.80 mL, 4.6 mmol) was
slowly added. After stirring at ambient temperature for 2 h, the
solution was concentrated to obtain the analytically pure product
as a yellow powder. Yield: 2.00 g, 4.4 mmol, 98%. 1H NMR (C6D6,
400 MHz, 25 °C): δ = 1.05 [d, JH,H = 6.4 Hz, 24 H, CH(CH3)2],
3.16 [sept, JH,H = 6.4 Hz, 4 H, CH(CH3)2], 6.90 (s, 2 H, 3,4-pyr),
7.31 (m, 6 H, Ph), 8.18 (s, 2 H, N=CH) ppm. 13C{1H} NMR
(C6D6, 100.4 MHz, 25 °C): δ = 24.0 [CH(CH3)2], 28.4 [CH(CH3)2],
120.6 (3,4-pyr), 123.8 (Ph), 125.3 (Ph), 140.6 (2,5-pyr), 145.1 (Ph),
147.5 (Ph), 163.0 (N=CH) ppm.
1
tals were obtained from hot thf. Yield: 0.48 g, 0.6 mmol, 60%. H
NMR ([D8]thf, 400 MHz, 25 °C): δ = 1.00 [d, JH,H = 6.7 Hz, 12 H,
CH(CH3)2], 1.20 [d, JH,H = 6.7 Hz, 12 H, CH(CH3)2], 3.71 [sept,
JH,H = 6.7 Hz, 4 H, CH(CH3)2], 6.57 (s, 2 H, 3,4-pyr), 6.95–7.13
(m, 6 H, Ph), 8.07 (s, 2 H, N=CH) ppm. 13C{1H} NMR ([D8]thf,
100.4 MHz, 25 °C): δ = 22.6 [CH(CH3)2], 26.7 [CH(CH3)2], 28.1
[CH(CH3)2], 117.5 (3,4-pyr), 123.9 (Ph), 126.4 (Ph), 142.3 (2,5-pyr),
142.7 (Ph), 150.1 (Ph), 164.7 (N=CH) ppm. C38H54Cl2N3O2Y
(744.67): calcd. C 61.29, H 7.31, N 5.6; found C 61.57, H 7.44, N
5.57. 4b: LuCl3: 0.42 g, 1.5 mmol; [(dip2-pyr)K]: 0.67 g, 1.4 mmol.
1H NMR ([D8]thf, 400 MHz, 25 °C): δ = 1.00 [d, JH,H = 6.7 Hz,
12 H, CH(CH3)2], 1.21 [d, JH,H = 6.7 Hz, 12 H, CH(CH3)2], 3.75
[sept, JH,H = 6.7 Hz, 4 H, CH(CH3)2], 6.61 (s, 2 H, 3,4-pyr), 7.09–
7.14 (m, 6 H, Ph), 8.11 (s, 2 H, N=CH) ppm. 13C{1H}NMR ([D8]-
thf, 100.4 MHz, 25 °C): δ = 22.6 [CH(CH3)2], 26.8 [CH(CH3)2],
28.0 [CH(CH3)2], 117.4 (3,4-pyr), 123.9 (Ph), 126.4 (Ph), 142.3 (2,5-
pyr), 142.8 (Ph), 150.3 (Ph), 164.3 (N=CH) ppm.
C38H54Cl2LuN3O2 (830.73): calcd. C 54.94, H 6.55, N 5.06; found
C 54.74, H 6.38, N 5.03.
[(dip2-pyr)Y(η5-C5H5)2] (5). Route A: thf (10 mL) was condensed at
–78 °C onto a mixture of 3 (0.43 g, 0.5 mmol) and Na(C5H5)
(0.09 g, 1 mmol), and the mixture was stirred at ambient tempera-
ture for 18 h. The solution was then concentrated, and the remain-
ing residue was extracted with toluene (10 mL). The solution was
concentrated and the remaining residue washed with n-pentane.
Route B: thf (10 mL) was condensed at –78 °C onto a mixture of
4a (0.37 g, 0.5 mmol) and Na(C5H5) (0.09 g, 1 mmol), and the mix-
ture was stirred at ambient temperature for 18 h. The solution was
then concentrated, and the remaining residue was extracted with
toluene (10 mL). The solution was then filtered and concentrated
until a white residue appeared. The residue was dissolved by heat-
ing, and the remaining yellow solution was allowed to stand at
ambient temperature. Yellow crystals appeared after several hours.
X-ray quality crystals were collected directly from this crop. Yield:
0.17 g, 0.3 mmol, 60%. 1H NMR ([D8]thf, 400 MHz, 25 °C): δ =
1.09 [d, JH,H = 6.8 Hz, 12 H, CH(CH3)2], 1.21 [d, JH,H = 6.8 Hz,
12 H, CH(CH3)2], 3.29 [sept, JH,H = 6.8 Hz, 4 H, CH(CH3)2], 5.95
(s, 10 H, C5H5), 6.76 (s, 2 H, 3,4-pyr), 7.09–7.25 (m, 6 H, Ph), 8.06
(s, 2 H, N=CH) ppm. 13C{1H}NMR ([D8]thf, 100.4 MHz, 25 °C):
δ = 23.1 [CH(CH3)2], 27.8 [CH(CH3)2], 110.9 (C5H5), 118.9 (3,4-
pyr), 123.5 (Ph), 125.5 (Ph), 140.5 (2,5-pyr), 142.8 (Ph), 149.1 (Ph),
162.5 (N=CH) ppm. C40H48N3Y (659.74): calcd. C 72.82, H 7.33,
N 6.37; found C 72.80, H 7.72, N 6.32.
[(dip2-pyr)K] (2): To a mixture of KH (2.06 g, 4.6 mmol) and 2,5-
bis{[(2,6-diisopropylphenyl)imino]methyl}pyrrole (0.23 g, 5.8 mmol)
was added thf (50 mL). After gas evolution had stopped, the sus-
pension was heated to 60 °C for 12 h. Remaining KH was filtered
off, and the thf solution was concentrated, layered with pentane
and cooled to –24 °C to obtain the product as yellow microcrystal-
line needles. Yield: 2.13 g, 4.4 mmol, 95%. 1H NMR (C6D6,
400 MHz, 25 °C): δ = 1.13 [d, JH,H = 6.8 Hz, 24 H, CH(CH3)2],
3.18 [sept, JH,H = 6.8 Hz, 4 H, CH(CH3)2], 6.92 (s, 2 H, 3,4-pyr),
7.09–7.17 (m, 6 H, Ph), 8.14 (s, 2 H, N=CH) ppm. 13C{1H} NMR
(C6D6, 100.4 MHz, 25 °C): δ = 24.2 [CH(CH3)2], 28.2 [CH(CH3)2],
120.2 (3,4-pyr), 123.5 (Ph), 124.1 (Ph), 139.3 (2,5-pyr), 144.0 (Ph),
151.4 (Ph), 161.1 (N=CH) ppm.
[(dip2-pyr)YCl3Li(thf)3] (3): thf (10 mL) was condensed at –78 °C
onto a mixture of YCl3 (0.12 g, 0.6 mmol) and [Li(dip2-pyr)] (1)
(0.22 g, 0.5 mmol), and the mixture was stirred at ambient tempera-
ture for 18 h. The solution was concentrated, and the remaining
residue was extracted with toluene (10 mL). The product was ob-
tained as yellow crystals from an oversaturated thf solution. Crys-
tals suitable for X-ray diffraction were collected directly from this
X-ray Crystallographic Studies of 3–5: Crystals of 3–5 were coated
in mineral oil (Aldrich) and mounted on glass fibers. They were
transferred directly to the –73 °C cold stream of a STOE IPDS 2T
diffractometer with Mo-Kα radiation. Structures were solved using
1
crop. Yield: 0.23 g, 0.3 mmol, 60%. H NMR ([D8]thf, 400 MHz,
25 °C): δ = 1.00 [d, JH,H = 6.7 Hz, 12 H, CH(CH3)2], 1.21 [d, JH,H
= 6.7 Hz, 12 H, CH(CH3)2], 3.71 [sept, JH,H = 6.7 Hz, 4 H, SHELXS-97[18] and refined against F2 using SHELXL-97.[19] 3:
¯
C46H70Cl3LiN3O4Y (3·thf), triclinic, P1 (no. 2); lattice constants a
CH(CH3)2], 6.61 (s, 2 H, 3,4-pyr), 7.07–7.14 (m, 6 H, Ph), 8.08 (s,
2 H, N=CH) ppm. 13C{1H} NMR ([D8]thf, 100.4 MHz, 25 °C): δ = 10.7803(6), b = 14.7469(9), c = 17.7228(12) Å, α = 83.424(5), β
= 22.6 [CH(CH3)2], 24.0 [CH(CH3)2], 28.1 [CH(CH3)2], 117.5 (3,4- = 85.672(5), γ = 70.525(5)°, V = 2636.7(3) Å3, Z = 2; µ(Mo-Kα) =
pyr), 123.8 (Ph), 126.4 (Ph), 138.5 (Ph), 142.6 (2,5-pyr), 142.7 (Ph),
164.6 (N=CH) ppm. C46H70Cl3LiN3O4Y (3·thf) (931.28): C 59.31, tions measured, of which 7271 were considered observed with
H 7.59, N 4.51; found C 60.01, H 7.05, N 4.63.
IϾ2σ(I); max./min. residual electron density 1.098/–0.547 e/Å–3;
1.297 mm–1; θmax. = 25.0; 9210 (Rint = 0.0469) independent reflec-
1478
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Eur. J. Inorg. Chem. 2008, 1475–1479

2,5-Bis{[(2,6-diisopropylphenyl)imino]methyl}pyrrolyl Complexes
[3] Y. Matsuo, H. Tsurugi, T. Yamagata, K. Tani, K. Mashima,
Bull. Chem. Soc. Jpn. 2003, 76, 1965–1968.
[4] D. Dawson, D. A. Walker, M. Thornton-Pett, M. Bochmann,
J. Chem. Soc., Dalton Trans. 2000, 459–466.
[5] Y. Yoshida, S. Matsui, Y. Takagi, M. Mitani, M. Nitabaru, H.
Tanaka, T. Fujita, Chem. Lett. 2000, 1270–1271.
[6] Y. Matsuo, K. Mashima, K. Tani, Chem. Lett. 2000, 1114–
1115.
[7] H. Tsurugi, Y. Matsuo, T. Yamagata, K. Mashima, Organome-
tallics 2004, 23, 2797–2805.
[8] Y. Matsuo, K. Mashima, K. Tani, Organometallics 2001, 20,
3510–3518.
[9] R. Anwander, Top. Curr. Chem. 1996, 179, 33–112.
[10] P. W. Roesky, Organometallics 2002, 21, 4756–4761.
[11] Reviews: a) H. Schumann, J. A. Meese-Marktscheffel, L. Esser,
Chem. Rev. 1995, 95, 865–986; b) C. J. Schaverien, Adv. Or-
ganomet. Chem. 1994, 36, 283–363; c) H. Schumann, Angew.
Chem. 1984, 96, 475–493; Angew. Chem. Int. Ed. Engl. 1984,
23, 474–493.
464 parameters, R1 [IϾ2σ(I)] = 0.0672; wR2 (all data) = 0.1919.
4a: C38H54Cl2N3O2Y, orthorhombic, Pbca (no. 61); lattice con-
stants a = 19.8426(9), b = 16.2320(8), c = 24.170(2) Å, V =
7784.7(7) Å3, Z = 8; µ(Mo-Kα) = 1.670 mm–1; θmax. = 25.0; 6864
(Rint = 0.0713) independent reflections measured, of which 12788
were considered observed with IϾ2σ(I); max./min. residual elec-
tron density 0.302/–0.385 e/A–3; 422 parameters, R1 [IϾ2σ(I)] =
0.0514; wR2 (all data) = 0.0906. 5: C47H56N3Y (5·toluene), mono-
clinic, P21/n (no. 14); lattice constants a = 10.6172(7), b =
18.8255(12), c = 20.5107(14) Å, β = 93.443(5)°, V = 4092.2(5) Å3,
Z = 4; µ(Mo-Kα) = 1.460 mm–1; θmax. = 25.0; 7197 (Rint = 0.1090)
independent reflections measured, of which 4869 were considered
observed with IϾ2σ(I); max./min. residual electron density 1.216/
–1.009 e/A–3; 419 parameters, R1 [IϾ2σ(I)] = 0.0850; wR2 (all data)
= 0.2318. CCDC-668003 (3), -668004 (4a), and -668005 (5) contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[12] J. C. Yoder, M. W. Day, J. E. Bercaw, Organometallics 1998, 17,
4946–4958.
[13] L. Mao, Q. Shen, M. Xue, J. Sun, Organometallics 1997, 16,
3711–3714.
[14] M. D. Rausch, D. F. Foust, R. D. Rogers, J. L. Atwood, J. Or-
ganomet. Chem. 1984, 265, 241–248.
Acknowledgments
[15] M. D. Taylor, C. P. Carter, J. Inorg. Nucl. Chem. 1962, 24, 387–
391.
This work was supported by the Deutsche Forschungsgemeinschaft
(DFG) (“Schwerpunktprogramm Lanthanoidspezifische Funktion-
alitäten in Molekül und Material”) (SPP 1166) and the Fonds der
Chemischen Industrie.
[16] T. K. Panda, M. T. Gamer, P. W. Roesky, Organometallics 2003,
22, 877–878.
[17] Y. Matsuo, K. Mashima, K. Tani, Organometallics 2001, 20,
3510–3518.
[18] G. M. Sheldrick, SHELXS-97, Program of Crystal Structure
Solution, University of Göttingen, Germany, 1997.
[19] G. M. Sheldrick, SHELXL-97, Program of Crystal Structure
Refinement, University of Göttingen, Germany, 1997.
Received: November 19, 2007
[1]
G. J. P. Britovsek, V. C. Gibson, D. F. Wass, Angew. Chem.
1999, 111, 448–468; Angew. Chem. Int. Ed. 1999, 38, 428–447,
and references therein.
[2] R. Kempe, Angew. Chem. 2000, 112, 478–504; Angew. Chem.
Int. Ed. 2000, 39, 468–493, and references therein.
Published Online: February 5, 2008
Eur. J. Inorg. Chem. 2008, 1475–1479
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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