Syntheses and reactivities of bisaryloxo lanthanide chlorides and crystal structures of [Ln(ArO)2Cl(THF)2]·(MePh) (Ln = Er, Yb) and [Sm(ArO)2(THF)3]·(MePh) (ArO = 2,6-di-tert-butyl-4-methylphenoxo)

Article abstract of DOI:10.1016/S0277-5387(01)00939-1

Four bisaryloxo lanthanide chlorides Ln(ArO)₂Cl(THF)₂ (Ln = Sm (1), Er (2), Yb (3), Y (4)) (ArO = 2,6-di-tert-butyl-4-methylphenoxo) were synthesized by the reaction of anhydrous LnCl₃ with 2 equiv. of NaOAr in THF at room temperature in high yield. These chlorides can be used as starting materials to synthesize heteroleptic lanthanide aryloxides. Complex 3 reacted with 1 equiv. of MeCpNa in THF to form a complex (MeCp)Yb(ArO)₂(THF) (5) containing mixed ligands. The divalent aryloxo lanthanide complexes Sm(ArO)₂(THF)₃ (6) and Yb(ArO)₂(THF)₃ (7) were obtained in good yield by reducing compounds 1 and 3 with sodium metal in THF, respectively. Single crystal structures of complexes 2·PhMe, 3·PhMe and 6·PhMe were determined. Complexes 2 and 3 are isostructural, in which one chlorine atom, two aryloxo ligands and two THF molecules are coordinated to the central metal to form a distorted trigonal bipyramid geometry. Complex 6 has similar stereochemistry to that of 2 and 3.

Full text of DOI:10.1016/S0277-5387(01)00939-1

Polyhedron 20 (2001) 3201–3208
www.elsevier.com/locate/poly
Syntheses and reactivities of bisaryloxo lanthanide chlorides and
crystal structures of [Ln(ArO)2Cl(THF)2]·(MePh) (Ln=Er, Yb)
and [Sm(ArO)2(THF)3]·(MePh)
(ArO=2,6-di-tert-butyl-4-methylphenoxo)
Ying-Ming Yao a, Qi Shen a,b,*, Yue Zhang c, Ming-Qiang Xue a, Jie Sun b
a Department of Chemistry and Chemical Engineering, Suzhou Uni6ersity, Suzhou 215006, PR China
b Laboratory of Organometallic Chemistry, Chinese Academy of Sciences, Shanghai 200032, PR China
c Department of Chemistry, Nanjing Uni6ersity, Nanjing 210093, PR China
Received 4 May 2001; accepted 6 September 2001
Abstract
Four bisaryloxo lanthanide chlorides Ln(ArO)2Cl(THF)2 (Ln=Sm (1), Er (2), Yb (3), Y (4)) (ArO=2,6-di-tert-butyl-4-
methylphenoxo) were synthesized by the reaction of anhydrous LnCl3 with 2 equiv. of NaOAr in THF at room temperature in
high yield. These chlorides can be used as starting materials to synthesize heteroleptic lanthanide aryloxides. Complex 3 reacted
with 1 equiv. of MeCpNa in THF to form a complex (MeCp)Yb(ArO)2(THF) (5) containing mixed ligands. The divalent aryloxo
lanthanide complexes Sm(ArO)2(THF)3 (6) and Yb(ArO)2(THF)3 (7) were obtained in good yield by reducing compounds 1 and
3 with sodium metal in THF, respectively. Single crystal structures of complexes 2·PhMe, 3·PhMe and 6·PhMe were determined.
Complexes 2 and 3 are isostructural, in which one chlorine atom, two aryloxo ligands and two THF molecules are coordinated
to the central metal to form a distorted trigonal bipyramid geometry. Complex 6 has similar stereochemistry to that of 2 and 3.
© 2001 Published by Elsevier Science Ltd.
Keywords: Synthesis; Crystal structures; Reactivity; Lanthanide; Aryloxide; Chloride
1. Introduction
syntheses and crystal structures of mixed-ligand arylox-
ide lanthanide complexes in the literature [9–14]. How-
ever, most of these complexes are synthesized via
metathesis of an aryloxide ligand from tris(aryloxide)
precursors using MC5Me5 (M=Li, K). We have previ-
ously reported the synthesis and crystal structure of
aryloxo ytterbium dichloride Yb(ArO)Cl2(THF)3
(ArO=2,6-di-tert-butyl-4-methylphenoxo) [15], and
the result revealed that one bulky aryloxo ligand can
stabilize the lanthanide atom to form a monomeric
complex. Our recent research indicated that bisaryloxo
lanthanide chlorides can also be synthesized in a
straightforward manner by the reaction of anhydrous
LnCl3 with 2 equiv. of NaOAr in THF. They can be
further transformed to mixed-ligand aryloxide lan-
thanide complexes and divalent lanthanide aryloxides
conveniently.
In recent years, lanthanide alkoxides and aryloxides
have found a variety of applications as homogeneous
catalysts for organic reactions [1] and precursors for
organolanthanide syntheses [2] and high purity oxide
materials [3]. The syntheses and structural studies of
aryloxo lanthanide complexes have revealed that the
low-coordinate lanthanide complexes can be easily ob-
tained using bulky aryloxo ligands [4–7]; for example,
the 2,6-di-tert-butyl substituents on the arene ring in
three-coordinate Ln(OAr)3 can completely block the
approach of other ligands to the coordination sphere of
the lanthanoid metal [8]. There are some reports on the
* Corresponding author. Fax: +86-512-511-2371.
E-mail address: qshen@suda.edu.cn (Q. Shen).
0277-5387/01/$ - see front matter © 2001 Published by Elsevier Science Ltd.
PII: S0277-5387(01)00939-1

3202
Y.-M. Yao et al. / Polyhedron 20 (2001) 3201–3208
2. Experimental
2.3. Synthesis of [Yb(ArO)2Cl(THF)2]·(MePh)
(3·MePh)
All manipulations were performed under argon using
the Schlenk technique. THF and toluene were distilled
from sodium benzophenone ketyl before use. Anhy-
drous lanthanide trichlorides were prepared according
to the literature method [16]. NaOAr and MeCpNa
were prepared from the reaction of ArOH and MeCpH
with Na in THF, respectively. Metal analyses were
performed by EDTA titration with xylenol orange indi-
cator and hexamine buffer [17] and chlorine analyses
were carried out using the Volhard method. Carbon
and hydrogen analyses were performed by direct com-
bustion. The IR spectra were recorded on a Nicolet-550
The synthesis of compound 3 was carried out as
described for 1, but anhydrous YbCl3 (0.91 g, 3.26
mmol) was used in place of SmCl3. Red microcrystals
were obtained from toluene solution (2.15 g, 74.6%).
m.p. 102–104 °C (dec.). Found: C, 60.65; H, 7.43; Cl,
4.21; Yb, 19.71; Anal. Calc. for [Yb(ArO)2Cl(THF)2]·
(MePh): C, 61.18; H, 7.98; Cl, 4.01; Yb, 19.58%; wmax
(cm−1) 2957(s), 2915(w), 2872(w), 1635(s), 1433(s),
1396(m), 1363(m), 1230(s), 1152(s), 1120(w), 866(s),
771(s). Crystals suitable for X-ray crystal structure
studies were obtained by recrystallization from THF–
toluene solution at −5 °C in 2 weeks.
1
FT-IR spectrometer as KBr pellets. H and 13C NMR
spectra were recorded on a Varian-400 spectrometer in
C6D6. Electron ionization mass spectrum (EI MS) was
performed on a HP5989A spectrometer. Uncorrected
melting points of crystalline samples in sealed capil-
laries (under an argon atmosphere) are reported as
ranges.
2.4. Synthesis of [Y(ArO)2Cl(THF)2]·(MePh) (4·MePh)
The synthesis of compound 4 was carried out as
described for 1, but anhydrous YCl3 (1.14 g, 5.83
mmol) was used instead of SmCl3. Colorless micro
crystals were obtained (3.16 g, 69.7%). m.p. 117−
119 °C (dec.). Found: C, 66.85; H, 8.44; Cl, 4.63; Y,
11.64; Anal. Calc. for [Y(ArO)2Cl(THF)2]·(MePh): C,
2.1. Synthesis of [Sm(ArO)2Cl(THF)2]·(MePh)
(1·MePh)
67.61; H, 8.83; Cl, 4.43; Y, 11.12%; wmax (cm−1
)
To a suspension of SmCl3 (0.98 g, 3.82 mmol) in 30
cm3 THF was slowly added a solution of NaOAr (9.5
cm3, 7.64 mmol) in THF at room temperature (r.t.).
After being stirred for 48 h, the NaCl was separated
from the reaction mixture by centrifugation. The sol-
vent was completely removed in vacuum and toluene
was added to extract the product. The dissolved portion
was removed by centrifugation. Yellow micro crystals
were obtained from the concentrated solution (2.37 g,
72.1%). m.p. 120–122 °C (dec.). Found: C, 62.43; H,
7.93; Cl, 4.31; Sm, 17.24; Anal. Calc. for [Sm(ArO)2-
Cl(THF)2]·(MePh): C, 62.78; H, 8.19; Cl, 4.12; Sm,
17.47%; wmax (cm−1) 2958(s), 2915(w), 2872(w), 1635(s),
1432(s), 1396(m), 1365(m), 1231(m), 1155(m), 1119(m),
864(s), 771(s).
2959(s), 2916(m), 2874(w), 1636(s), 1431(s), 1396(m),
1365(m), 1231(s), 1153(s), 1118(m), 864(s), 772(s). H
1
NMR (C6D6): l=1.18 (s, 8H, THF), 1.74 (s, 36H,
ꢀCMe3), 2.39 (s, 6H, Me(Ar)), 3.87 (s, 8H, THF), 7.33
(s, 4H, Ar); 13C NMR (C6D6): l=21.90 (Me(Ar)),
25.66 (THF), 32.52 (Me3C), 35.98 (CMe3), 71.98
(THF), 125.54 (Ar), 126.72 (Ar), 138.86 (Ar), 160.84
Ar).
2.5. Synthesis of (MeCp)Yb(ArO)2(THF) (5)
2.5.1. Method A
To a THF solution (20 cm3) of complex 3 (0.85 g,
1.07 mmol) was added a solution of MeCpNa (1.6 cm3,
1.07 mmol) in THF, the resulting solution was stirred
at r.t. for 24 h. After centrifugation, the solution was
concentrated and about 10 cm3 toluene was added. The
solution was cooled to −10 °C and red crystals were
obtained in a few weeks (0.45 g, 55.1%). m.p. 102–
104 °C (dec.). Found: C, 62.43; H, 8.15; Yb, 23.02;
Anal. Calc. for (MeCp)Yb(ArO)2(THF): C, 62.97; H,
8.06; Yb, 22.67%; nmax (cm−1) 2958(s), 2906(w),
2880(w), 1628(s), 1434(s), 1396(m), 1362(m), 1231(m),
1151(s), 1065(m), 1027(w), 864(s), 771(s), 460(m). MS
(70 eV): m/z (%) 691 (5.5, M+−THF), 612 (1.5, M+
−THF−MeCp), 551 (17.8, M+−THF−2But−
2Me), 472 (23.6, M+−THF−MeCp−2But−Me),
456 (20.7, M+−THF−MeCp−2But−2Me), 377
(26.3, M+−THF−MeCp−ArO−Me), 332 (17.0,
M+−THF−MeCp−ArO−But), 253 (21.0, M+−
THF−MeCp−ArO−2But−Me).
2.2. Synthesis of [Er(ArO)2Cl(THF)2]·(MePh)
(2·MePh)
The synthesis of compound 2 was carried out as
described for 1, but anhydrous ErCl3 (1.25 g, 4.57
mmol) was used instead of SmCl3. Pink microcrystals
were obtained from toluene solution (2.71 g, 67.5%).
m.p. 113–115 °C (dec.). Found: C, 60.96; H, 7.42; Cl,
4.11; Er, 19.23; Anal. Calc. for [Er(ArO)2Cl(THF)2]·
(MePh): C, 61.58; H, 8.04; Cl, 4.04; Er, 19.05%; wmax
(cm−1) 2957(s), 2917(w), 2873(w), 1634(s), 1433(s),
1396(m), 1365(m), 1231(m), 1154(s), 1118(m), 1027(w),
864(s), 771(s). Crystals suitable for X-ray crystal struc-
ture studies were obtained by recrystallization from
THF–toluene solution at −10 °C over a few days.

Y.-M. Yao et al. / Polyhedron 20 (2001) 3201–3208
3203
2.5.2. Method B
61.43; H, 8.76; Yb, 20.37; Anal. Calc. for Yb(ArO)2-
(THF)3: C, 60.92; H, 8.52; Yb, 20.89%; wmax (cm−1
2958(s), 2916(w), 2872(w), 1633(s), 1435(s), 1392(m),
1361(m), 1232(s), 1150(s), 1121(w), 864(s), 772(s).
To a slurry of anhydrous YbCl3 (1.02 g, 3.65 mmol)
in about 40 cm3 THF was slowly added a solution of
NaOAr (9.1 cm3, 7.30 mmol) in THF at r.t. After
YbCl3 disappeared completely, a THF solution of
MeCpNa (5.5 cm3, 3.65 mmol) was added slowly. The
mixture was stirred at r.t. for 72 h, then the NaCl was
removed from the reaction mixture by centrifugation.
THF was completely removed in vacuum and toluene
was added to extract the product. The precipitation was
removed again by centrifugation. Red microcrystals
were obtained from the concd. toluene solution (1.73 g,
62.4%).
)
2.8. Crystallography
Single crystals suitable for X-ray measurements were
sealed in thin-walled glass capillaries under argon. In-
tensity data were collected in the variable ꢀ scan mode
on a four-circle diffractometer (Siemens R3m/V for
2·PhMe, Rigaku AFC 7R for 3·PhMe and Nicolet
R3M/E for 6·PhMe) using Mo Ka radiation (u=
,
0.71073 A) at 293 K. Crystallographic data are list in
Table 1.
2.6. Synthesis of [Sm(ArO)2(THF)3]·(MePh) (6·MePh)
The crystal structures of these complexes were solved
with the Patterson superposition method and subse-
quent difference Fourier syntheses were employed to
locate the remaining non-hydrogen atoms. All the non-
hydrogen atoms were refined anisotropically. Hydrogen
atoms were all generated geometrically (CꢀH bond
2.6.1. Method A
To a THF solution (30 cm3) of Sm(ArO)2Cl(THF)2
(1) (1.73 g, 2.26 mmol) was added 1 equiv. of sodium
chips. The mixture was stirred at 40 °C for 3 days the
color of the solution changed gradually from orange
yellow to dark brown. The precipitate was separated by
centrifugation and the solvent was evaporated com-
pletely under reduce pressure. Then toluene was added
to extract the product and the dissolved portion was
separated by centrifugation. Large dark brown crystals
were obtained from a concd. toluene solution at r.t. in
2 days (1.32 g, 65.2%). m.p. 146–148 °C (dec.). Found:
C, 64.96; H, 8.32; Sm, 17.01; Anal. Calc. for
[Sm(ArO)2(THF)3]·(MePh): C, 65.57; H, 8.76; Sm,
16.76%; wmax (cm−1) 2957(s), 2912(w), 2872(w), 1631(s),
1431(s), 1396(m), 1362(m), 1231(m), 1152(m), 1120(m),
1061(w), 866(s), 771(s).
,
lengths fixed at 0.96 A), assigned appropriate isotropic
thermal parameters and allowed to ride on their parent
carbon atoms. All the H atoms were held stationary
and included in the structure factor calculation in the
final stage of full-matrix least-squares refinement.
3. Results and discussion
3.1. Syntheses of Ln(ArO)2Cl(THF)2 (Ln=Sm (1), Er
(2), Yb (3), Y (4))
2.6.2. Method B
Although examples of the syntheses and crystal struc-
tures of homoleptic and heteroleptic alkoxo and ary-
loxo lanthanide complexes are plentiful in the literature
[4,5,7,18–23], the synthesis of alkoxo and aryloxo lan-
thanide halides is seldom reported. An analogous reac-
tion of anhydrous lanthanide chlorides with 2 or 3
equiv. of NaOBut or NaOPri has been studied previ-
ously; however, polynuclear lanthanide chloride com-
plexes were obtained [24–26]. Using more bulky
alkoxides such as Bu3t CO-, Ph3CO- as ligands, the
expected alkoxo lanthanide chlorides were obtained
[27,28]. Reactions of the divalent aryloxo samarium
complex Sm(OAr)2(THF)3 with ClCH2CH2Cl, ButCl or
iodine in THF afforded the aryloxide samarium halides
in good yields by Hou and co-workers, and X-ray
crystal structure studies revealed that the chloride pos-
sessed a dimeric structure via a Sm–Cl interaction
[Sm(ArO)2(m-Cl)(THF)]2 and the iodide was monomeric
Sm(ArO)2I(THF)2 [29]. In our case, using a bulky
aryloxo ligand, the stoichiometrically expected products
were obtained conveniently. The metathesis reaction of
anhydrous LnCl3 and NaOAr in molar ratio 1:2 in
To a suspension of SmCl3 (1.26 g, 4.91 mmol) in 40
cm3 THF was slowly added a solution of NaOAr (12.2
cm3, 6.51 mmol) in THF at r.t. After being stirred for
24 h, 1 equiv. of sodium chips was added. The mixture
was stirred at r.t. for 5 days and the color of the
solution changed gradually from orange yellow to dark
brown. The precipitate was separated by centrifugation
and the solvent was evaporated completely under re-
duce pressure. Then toluene was added to extract the
product and the dissolved portion was separated by
centrifugation. Block dark brown crystals were ob-
tained from concd. toluene solution (3.31 g, 75.3%).
2.7. Synthesis of Yb(ArO)2(THF)3 (7)
The synthesis of compound 7 was carried out as
described in method A for 6, but Yb(ArO)2Cl(THF)2
(3) (2.64 g, 3.34 mmol) was used instead of
Sm(ArO)2Cl(THF)2. Yellow crystals were obtained
from concd. toluene solution at −5 °C in a few weeks
(2.01 g, 72.8%). m.p. 121–123 °C (dec.). Found: C,

3204
Y.-M. Yao et al. / Polyhedron 20 (2001) 3201–3208
THF at room temperature, followed by crystallization
from THF–toluene mixture solvent, gave the neutral
lanthanide aryloxide chlorides Ln(ArO)2Cl(THF)2
(Ln=Sm (1), Er (2), Yb (3), Y (4)) in high yield, as
shown in Eq. (1).
spectra did not show any resonance peak for the tolu-
ene molecule of crystallization, the toluene molecule
was presumably lost during drying under vacuum. The
analytical results also revealed that these bisaryloxo
lanthanide compounds had monomeric structures,
which is different from that of [Sm(ArO)2(m-Cl)(THF)]2
[29].
LnCl3+2NaOArT“HF(ArO)2LnCl(THF)2+2NaCl (1)
Ln=Sm(1), Er(2), Yb(3), Y(4)
ArO=2,6-t-Bu -4-MeC H O
2
6 2
3.2. Reacti6ities of Ln(ArO)2Cl(THF)2 (Ln=Sm (1),
Yb (3))
Complexes 1·PhMe to 4·PhMe gave satisfactory ele-
mental analyses and their infrared spectra showed ab-
sorptions characteristic of the ArO ligand. It is not
possible to establish the presence of coordinated THF
from the infrared spectra owing to the ArO absorption
in the 900–800 cm−1 region. For the diamagnetic
yttrium compound 4, the 1H and 13C NMR spectra
were obtained in C6D6. In the 1H NMR spectrum, there
are not only the resonances of ArO ligands, but also
two distinct singlet resonances of THF molecules at
l=3.87 and 1.18 which integrated for 16H, indicating
that two THF molecules coordinate to the central
metal. Only one set of signals for the ArO ligands (two
signals for 2,6-CMe3 (1.74), 4-Me (2.39) and one signal
3.2.1. Metathesis reaction of Yb(ArO)2Cl(THF)2 (3)
The metathesis reaction of Yb(ArO)2Cl(THF)2 (3)
with 1 equiv. of MeCpNa in THF proceeds smoothly to
afford the monocyclopentadienyl aryloxo ytterbium
complex (h5-MeCp)Yb(ArO)2(THF) (5) in good yield
Eq. (2):
(Aro)2YbCl+MeCpNaTꢀHꢀFꢁ(MeCp)Yb(OAr)2(THF)
(3)
(5)
+NaCl
(2)
Complex 5 is soluble in hydrocarbon solvents such as
toluene, and this compound is confirmed by elemental
analyses, infrared and mass spectrum. Chlorine analysis
shows that no chlorine exists. In the IR spectrum, as
well as the characteristic absorption bands of the ary-
loxo ligand, there are absorption peaks of methylcy-
clopentadienyl ligand apparent. The mass spectrum
clearly reveals a molecular ion peak without the THF
molecule (m/z=691) and related fragments. The ana-
1
for the ring protons (7.34)) appeared in the H NMR
spectrum. Likewise, in the 13C NMR spectrum, only
one set of signals for the ArO ligands were recorded,
revealing that the two ArO ligands in the molecule are
equivalent. X-ray structural studies of complexes 2 and
3 revealed that there is one toluene molecule as lattice
solvent per formula unit. As the 1H and 13C NMR
Table 1
Crystal data and experimental parameters
Compound
2·MePh
45H70ClErO4
877.7
293(2)
tetragonal
pink, prism
I41/acd (no. 142)
3·MePh
6·MePh
Formula
C
C45H70ClO4Yb
883.5
293(2)
tetragonal
red, prism
I41/acd (no. 142)
C49H78O5Sm
897.5
298(2)
monoclinic
Brown, block
P21/c (no. 14)
Molecular weight
Temperature (K)
Crystal system
Crystal color and habit
Space group
Lattice parameters
,
a (A)
18.868(1)
18.868(1)
52.165(1)
90
18571(1)
1.256
18.824(3)
18.824(3)
52.265(11)
90
18519.7(53)
1.247
15.510(5)
16.179(4)
19.865(6)
97.42(2)
4943.08(2)
1.21
,
b (A)
,
c (A)
i (°)
3
,
V (A )
Dcalc (g cm−3
)
Z
16
1.901
7312
16
2.127
7344
4
1.23
1896
v (mm−1
F(000)
)
Crystal size (mm)
qmax (°)
0.55×0.50×0.50
26.06
0.30×0.20×0.20
25.00
0.10×0.46×0.68
25.00
Reflections collected
Independent reflections
Reflections with I]2.0|(I)
Parameters refined
R
8965
4592
2240
270
0.0673
0.1203
3234
3177
1801
274
0.0492
0.1403
8014
4399
3314 [I]3.0|(I)]
465
0.0597
wR2
0.0539 (Rw)

Y.-M. Yao et al. / Polyhedron 20 (2001) 3201–3208
3205
Table 2
Selected bond lengths (A) and angles (°) in compounds 2 and 3
C5Me5)La(O-2,6-t-Bu2C6H3)2(THF)2 to form a mixture
,
of Cp*La(OAr%), Cp*La(OAr%)2 and La(OAr%)3 [11]. In
2
our case, the bisaryloxo lanthanide chloride was used as
starting material to synthesize the mixed-ligand com-
plex and no evidence of such solution behavior was
observed. The reaction of bisaryloxo lanthanide chlo-
ride with other anionic ligands is being studied in detail
by our group.
Er(OAr)2Cl(THF)2·
MePh
Yb(OAr)2Cl(THF)2·
MePh
Bond lengths
LnꢀO(1)
LnꢀO(2)
LnꢀCl(1)
O(1)ꢀC(1)
2.097(5)
2.321(5)
2.494(3)
1.354(8)
2.080(1)
2.295(1)
2.477(9)
1.344(2)
3.2.2. Reduction of Ln(ArO)2Cl(THF)2 (Ln=Sm (1),
Yb (3))
Bond angles
O(1)ꢀLnꢀO(1a)
O(1)ꢀLnꢀO(2)
O(1)ꢀLnꢀO(2a)
O(1)ꢀLnꢀCl(1)
O(2)ꢀLnꢀO(2a)
O(2)ꢀLnꢀCl(1)
LnꢀO(1)ꢀC(1)
LnꢀO(2)ꢀC(16)
LnꢀO(2)ꢀC(19)
149.7(3)
90.1(2)
87.6(2)
105.1(1)
171.0(3)
94.5(1)
173.6(5)
132.6(7)
120.2(7)
151.51(7)
89.89(5)
87.92(5)
104.24(3)
171.1(7)
94.44(4)
172.5(1)
136.2(2)
121.0(2)
Generally, the methods of synthesis of divalent ary-
loxo lanthanide complexes involve: (i) protolytic ex-
change; (ii) redox transmetallation; (iii) metathesis
reaction; (iv) direct reaction of lanthanide metal and
ligand in benzophenone or liquid ammonia [30]. The
syntheses of divalent complexes 6 and 7 have been
described previously by the reaction of HOC6H2But2-
2,6-Me-4 with Ln[N(SiMe3)2]2 or KOC6H2But2-2,6-Me-
4 with LnI2 and structurally characterized [30–34]. We
previously reported the single crystal structure of
6·THF which was synthesized by a reduction method,
but this is a one-pot reaction (Method B), and the
precursor was not separated and characterized [35]. The
reactions of Sm(ArO)2Cl(THF)2 (1) and Yb(ArO)2Cl-
(THF)2 (3) with 1 equiv. of sodium in THF smoothly
produce the divalent aryloxo lanthanide complexes
Sm(ArO)2(THF)3 (6) and Yb(ArO)2(THF)3 (7), respec-
tively (Eq. (4)).
Table 3
,
Selected bond lengths (A) and angles (°) in compound 6
Bond lengths
SmꢀO(1)
SmꢀO(3)
SmꢀO(5)
O(2)ꢀC(21)
2.339(5)
2.594(7)
2.558(7)
1.35(1)
SmꢀO(2)
SmꢀO(4)
O(1)ꢀC(11)
2.332(7)
2.580(7)
1.31(1)
Bond angles
O(1)ꢀSmꢀO(2)
O(2)ꢀSmꢀO(3)
O(2)ꢀSmꢀO(4)
O(1)ꢀSmꢀO(5)
O(3)ꢀSmꢀO(5)
SmꢀO(1)ꢀC(11)
SmꢀO(3)ꢀC(31)
SmꢀO(4)ꢀC(41)
SmꢀO(5)ꢀC(51)
148.3(2)
89.6(2)
93.2(2)
105.6(2)
91.5(3)
174.5(6)
125.8(6)
127.7(7)
122.7(8)
O(1)ꢀSmꢀO(3)
O(1)ꢀSmꢀO(4)
O(3)ꢀSmꢀO(4)
O(2)ꢀSmꢀO(5)
O(4)ꢀSmꢀO(5)
SmꢀO(2)ꢀC(21)
SmꢀO(3)ꢀC(34)
SmꢀO(4)ꢀC(44)
SmꢀO(5)ꢀC(54)
87.8(2)
90.8(2)
176.6(2)
106.1(2)
85.9(3)
172.1(7)
125.8(6)
130.2(7)
129.3(7)
(ArO)2LnCl+NaT“HF(ArO)2Ln(THF)3+NaCl
(4)
Ln=Sm (6), Yb (7); ArO=2,6-t-Bu -4-MeC H O
2
6 2
Recrystallization from concentrated toluene solution
gave 6 and 7 as dark-brown and yellow block crystals,
respectively. Solvent plays an important role in the
reduction reaction; using toluene as solvent, the reduc-
tion reaction does not proceed although the starting
material and the product all can dissolve in toluene.
lytical results demonstrate that complex 5 is the known
compound that we have previously synthesized by a
one-pot reaction of anhydrous YbCl3 and 2 equiv. of
NaOAr and 1 equiv. of MeCpNa in THF [14].
There are a lot of examples on the syntheses and
crystal structures of bisaryloxo mixed-ligand lanthanide
complexes in literature; however, almost all of them are
synthesized by the metathesis reaction of trisaryloxo
lanthanide complexes with 1 equiv. of MC5Me5 Eq. (3)
[9–13]:
3.3. Crystal structures
The molecular structures of complexes 2·MePh,
3·MePh and 6·MePh were determined by single-crystal
structure studies. The selected bond distances and an-
gles are listed in Tables 2 and 3.
3.3.1. Molecular structures of
[Ln(ArO)2Cl(THF)2]·(MePh) (2·MePh, 3·MePh)
Complexes 2·MePh and 3·MePh are isostructural,
and the monomeric structure is shown in Fig. 1. The
central lanthanide metal ion is five-coordinate with two
aryloxo oxygen atoms, one chlorine atom and two THF
oxygen atoms in a distorted trigonal bipyramid geome-
try. There is a twofold axis which passes through both
the samarium and chlorine atoms. The two bulky ary-
loxo oxygen atoms and the chlorine atom form the
equatorial vertices, the two THF ligands occupy the
Ln(OAr%)3+MC5Me5“(C5Me5)Ln(OAr%)2+MOAr%
M=Li, Ln=La, Ce, Sm;
M=K, Ln=Y
Ar%O=2,6-t-Bu C H
6 3
2
(3)
It has been reported that there is ligand redistribu-
tion in solution for the bisaryloxo lanthanum com-
plexes (h5-C5Me5)La(O-2,6-t-Bu2C6H3)2 and (h5-

3206
Y.-M. Yao et al. / Polyhedron 20 (2001) 3201–3208
,
from this value gives 1.49 A. This is much higher than
apical positions. The stereochemistry of these two com-
pounds is similar to that for Sm(ArO)2I(THF)2 [29], but
different from that of [Sm(ArO)2(m-Cl)(THF)]2 [29]
which has a square pyramidal structure. Actually, for
five-coordinate monomeric aryloxo lanthanide com-
plexes, the trigonal bipyramid coordination fashion is
common. There are few examples, such as Yb(ArO)2-
(THF)3 [33], Yb(Odpp)3(THF)2 (Odpp=2,6-diphenyl-
phenolate) [36], Yb(Odpp)3DME (DME=1,2-dime-
thoxyethane) [22], Nd(Odpp)3DME [22] and Yb(OC6-
H2But3-2,4,6)2(THF)3·THF [37], which have square
pyramidal geometry.
,
the usual value of 1.34 A for organolanthanoid com-
plexes [45], but is still comparable with other aryloxo
lanthanide complexes [36,41,42].
It is interesting to compare the coordinate geometries
of complex 3 and Yb(ArO)Cl2(THF)3 [15], which is a
six-coordinate, pseudo-octahedral complex. The reduc-
tion in coordination number from Yb(ArO)Cl2(THF)3
to 3 may be attributed to the increasing steric require-
ments of an additional bulky ArO ligand instead of
chlorine in the coordination sphere of the central metal.
,
The YbꢀO(Ar) bond length is 2.080(1) A in complex
,
The ErꢀO(Ar) bond length in 2 is 2.097(5) A, a little
,
3, subtraction of the estimated ionic radius (0.81 A) [39]
longer than the value in Er(OC6H3Pri2-2,6)3(THF)2
for five-coordinate Yb 3+ from this value gives 1.27 A.
,
,
(2.072(10) A) [38], although both of them have similar
Similar treatment of the YbꢀO(Ar) distance for com-
plex Yb(ArO)Cl2(THF)3 gives 1.21 A [15]. These values
stereochemical arrangement around the erbium atoms
and there are three aryloxo ligands coordinated to the
central metal in the latter. This is consistent with the
fact that the ArO ligand is more bulky than the
,
suggest that there is a higher degree of steric congestion
in complex 3, and it is consistent with the change in
coordination number for these two complexes. How-
ever, the present value in complex 3 is comparable with
those values in aryloxo lanthanide (III) complexes, such
as complex 2 (1.27), Sm(ArO)2I(THF)2 (1.26 A) [29],
Yb(OC6H2Bu3-2,4,6)3(THF) (1.27 A) [46], Yb(Odpp)3-
(THF)2(THF) (1.27 A) [36] and Yb(Odpp)3DME (1.25
A) [22]. Five coordination has also been found in the
bulky alkoxo ytterbium compound, [YbI(m-OCPh3)-
DME]2 [28], in which the YbꢀO(R) distances (2.299(4),
2.302(5) A) are longer than the YbꢀO(Ar) distance in
complex 3 due to the ionic radius difference between di-
OC6H3Pri2-2,6 ligand. Subtraction of the estimated ra-
3+
,
dius (0.83 A) [39] for five-coordinate Er
from
,
ErꢀO(Ar) gives 1.27 A, which is a little shorter than the
values for other aryloxo lanthanide complexes
K[Er(OC6H3Pr2-2,6)4] (1.31 A) [40], [Na(diglyme)2]-
,
t
,
i
,
,
[Er(OC6H3Pri2-2,6)4]
(diglyme=bis(2-methoxyethyl)
,
,
,
ether) (1.31 A) [19], [Sm(ArO)3(THF)](THF) (1.34 A)
,
[41] and Sc(OAr)3 (1.30 A) [8]. But it is comparable
,
with those for (ArO)2SmI(THF)2 (1.26 A) [29] and
La(Odpp)3(THF)2 (1.28 A) [42]. The ErꢀCl bond dis-
tance is 2.494(3) A, which is comparable with those for
[(C5H5)2Er(m-Cl)]2 (2.666(4) A) [43] and (C5H5)ErCl2-
(THF)3 (2.616(9) A) [44] when the difference in coordi-
,
,
,
and trivalent species.
,
,
The YbꢀCl distance of complex 3 is 2.4770(9) A. This
value is comparable with those values in Yb(ArO)-
Cl2(THF)3 (2.555(2)) [15], YbCl3(THF)3 (2.52(7) A) [47]
and CpYbCl2(THF)3 (2.594(3) A) [48] when the differ-
ence in coordination number is considered. The
YbꢀO(THF) bond length is 2.2946(14) A, and a similar
subtraction from this value gives 1.48 A. This value is
,
nation number among these compounds is considered.
This value is apparently shorter than that for
[Sm(ArO)2(m-Cl)(THF)]2 [29] even if the differences in
ionic radii are considered due to the formation of the
bridging bond. The ErꢀO(THF) bond length is 2.321(5)
,
,
,
,
,
A, and a similar subtraction of the metal ionic radius
comparable with those values for Yb(ArO)Cl2(THF)3
,
,
(1.47 A) [15] and [Yb(Odpp)3(THF)2](THF) (1.49 A)
[36]. The CꢀO distance of the phenolate ligand is
,
1.344(2) A, which is similar to that in complex 2
(1.354(8) A), but it is apparently shorter than the single
,
bond length, reflecting substantial delocalization from
oxygen into the aromatic rings. The YbꢀO(1)ꢀC(1)
bond angle is 172.5(1)°, which is also comparable with
that in complex 2 (173.6(5)°). However, this value is
somewhat smaller than those in Yb(MeCp)(OAr)2-
(THF) (178.8(4)°) [14] and Yb(ArO)Cl2(THF)3
(179.7(3)°) [15] and apparently larger than those aver-
age values in trisaryloxo lanthanide compounds, [Sm-
(OAr)3(THF)]·(THF) (155.3(6)°) [41], [Nd(OAr)3-
(THF)](MePh) (155.9(5)°) [49]. This may be attributed
to the difference in steric crowding among these com-
pounds.
Fig. 1. Molecular structure of Ln(ArO)2Cl(THF)2·(MePh) (Ln=Er
(2), Yb (3)).

Y.-M. Yao et al. / Polyhedron 20 (2001) 3201–3208
3207
Fig. 2. Molecular structure of Sm(ArO)2(THF)3 with the atom-numbering scheme. The MePh lattice molecule has been omitted.
,
,
A) [29], 6·THF (2.304(8) A) [35] and [KSm(m-
3.3.2. Molecular structure of
[Sm(ArO)2(THF)3]·(MePh) (6·MePh)
,
OAr)3(THF)]n (2.339(7) A) [32], although the latter
forms bridge bonds. This value is also comparable with
those for [Eu(ArO)2(THF)3]·(THF) (2.329(5)) [30] and
Yb(ArO)2(THF)3 (2.206(15) A) [33] when the difference
in ionic radii is considered. The SmꢀO(THF) distances
range from 2.558(7) to 2.594(7) A, with an average of
2.577(7) A, and are well within the range of coordina-
tion bonds.
Complex 6 can be crystallized in three forms (6,
6·THF and 6·MePh) depending on recrystallization
conditions [29]. The single crystal structures of com-
pounds 6 [29] and 6·THF [35] were reported previously.
The full structure of 6·MePh was not reported until
now. Evans et al. reported the unit cell data for 6·MePh
,
,
,
,
with a=15.480(2), b=16.146(3), c=19.816(4) A and
i=97.45(1)°, and these data revealed this compound
has a monomeric structure. However, the accurate
structure of this compound was not given because of
the serious decomposition during data collection [32].
These parameters are consistent with those in this
work. Here we report the full molecular structure of
6·MePh.
The molecular structure of compound 6·MePh is
shown in Fig. 2. It is isostructural with 6 [29] and
6·THF [35]. The coordination polyhedron of the samar-
ium(II) atom is a distorted trigonal bipyramid, in which
two aryloxo ligands together with one THF ligand
(O(5)) form the triangular plane with angles
O(1)ꢀSmꢀO(2) 148.3(2), O(2)ꢀSmꢀO(5) 106.1(2),
O(1)ꢀSmꢀO(5) 105.6(2)°, and two THF ligands (O(3)
and O(4)) are placed at the apical positions in a near
linear fashion with an OSmO angle (O(3)ꢀSmꢀO(4) of
176.6(2)°). This coordination mode is similar to that of
the related europium(II) species [Eu(ArO)2(THF)3]-
(THF) [30], but in contrast to that of the ytterbium(II)
compound Yb(ArO)2(THF)3 (7) which has distorted
square pyramidal coordination [33].
4. Supplementary data
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Center, CCDC No. 153200 and 153201 for com-
pounds 2 and 3. Copies of this can be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax:+44-1223-336033; e-
mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk). The crystallographic data for
compound 6 were submitted as hardcopy.
Acknowledgements
Financial support from the Chinese National Natural
Science Foundation, the Key Laboratory of Organic
Synthesis of Jiangsu Province and Suzhou University is
gratefully acknowledged. Thanks are due to the De-
partment of Chemistry, The Chinese University of
Hong Kong, for carrying out the X-ray structure
determination.
,
The average SmꢀO(Ar) bond length is 2.335(7) A;
this value is comparable with those reported for other
aryloxo samarium(II) complexes, such as 6 (2.339(12)

3208
Y.-M. Yao et al. / Polyhedron 20 (2001) 3201–3208
[26] W.J. Evans, M.S. Sollberger, T.P. Hanusa, J. Am. Chem. Soc.
References
110 (1988) 1841.
[27] M. Wedler, J.W. Gilje, U. Pieper, D. Stalke, M. Noltemeyer,
F.T. Edelmann, Chem. Ber. 124 (1991) 1163.
[28] D.L. Duncalf, P.B. Hitchcock, G.A. Lawless, J. Chem. Soc.,
Chem. Commun. (1996) 269.
[29] Z.M. Hou, A. Fujita, T. Yoshimura, A. Jesorka, Y.G. Zhang, H.
Yamazaki, Y. Wakatsuki, Inorg. Chem. 35 (1996) 7190.
[30] J.R. Van den Hende, P.B. Hitchcock, S.A. Holmes, M.F. Lap-
pert, W.P. Leung, T.C.W. Mak, S. Prashar, J. Chem. Soc.,
Dalton Trans. (1995) 1427.
[31] Z.M. Hou, T. Miyano, H. Yamazaki, Y. Wakatsuki, J. Am.
Chem. Soc. 117 (1995) 4421.
[32] W.J. Evans, R. Anwander, M.A. Ansari, J.W. Ziller, Inorg.
Chem. 34 (1995) 5.
[33] G.B. Deacon, P.B. Hitchcock, S.A. Holmes, M.F. Lappert, P.
MacKinnon, R.H. Newnham, J. Chem. Soc., Chem. Commun.
(1989) 935.
[34] J.R. Van den Hende, P.B. Hitchcock, S.A. Holmes, M.F. Lap-
pert, J. Chem. Soc., Dalton Trans. (1995) 1435.
[35] G.Z. Qi, Q. Shen, Y.H. Lin, Acta Crystallogr., Sect. C 50 (1994)
1456.
[1] M. Shibasaki, H. Sasai, T. Arai, Angew. Chem., Int. Ed. Engl.
36 (1997) 1236.
[2] P.B. Hitchcock, M.F. Lappert, R.G. Smith, R.A. Bartlett, P.P.
Power, J. Chem. Soc., Chem. Commun. (1988) 1007.
[3] L.G. Hubert-Pfalzgraf, New J. Chem. 19 (1995) 727.
[4] R.C. Mehrotra, A. Singh, U.M. Tripathi, Chem. Rev. 91 (1991)
1287.
[5] F.T. Edelmann, Coord. Chem. Rev. 137 (1994) 403.
[6] W.J. Evans, New J. Chem. 19 (1995) 525.
[7] M.N. Bochkarev, L.N. Zakharov, G.S. Kalinina, Organoderiva-
tives of the Rare Earth, Kluwer Academic, Dordrecht, 1996.
[8] P.B. Hitchcock, M.F. Lappert, A. Singh, J. Chem. Soc., Chem.
Commun. (1983) 1499.
[9] H.J. Heeres, A. Meetsma, J.H. Teuben, J. Chem. Soc., Chem.
Commun. (1988) 962.
[10] H.J. Heeres, A. Meetsma, J.H. Teuben, R.D. Rogers,
Organometallics 8 (1989) 2637.
[11] H.J. Heeres, J.H. Teuben, Recl. Trav. Chim. Pays-Bas 109
(1990) 226.
[12] C.J. Schaverien, J.H.G. Frijns, H.J. Heeres, J.R. Van der Hende,
A. Meetsma, J.H. Teuben, A.L. Spek, J. Chem. Soc., Chem.
Commun. (1991) 642.
[36] G.B. Deacon, S. Nickel, P. MacKinnon, E.R.T. Tiekink, Aust. J.
Chem. 43 (1990) 1245.
[37] G.B. Deacon, T.C. Feng, P. MacKinnon, R.H. Newnham, S.
Nickel, B.W. Skelton, A.H. White, Aust. J. Chem. 46 (1993) 387.
[38] D.M. Barnhart, D.L. Clark, J.C. Gordon, J.C. Huffman, R.L.
Vincent, J.G. Watkin, B.D. Zwick, Inorg. Chem. 33 (1994) 3487.
[39] R.D. Shannon, Acta Crystallogr., Sect. A 32 (1976) 751.
[40] D.L. Clark, J.C. Gordon, J.C. Huffman, R.L. Vincent-Hollis,
J.G. Watkin, B.D. Zwick, Inorg. Chem. 33 (1994) 5903.
[41] Q.Z. Qi, Y.H. Lin, J.Y. Hu, Q. Shen, Polyhedron 14 (1995) 413.
[42] G.B. Deacon, B.M. Gatehouse, Q. Shen, G.N. Ward, E.R.T.
Tiekink, Polyhedron 12 (1993) 1289.
[13] R.J. Butcher, D.L. Clark, J.C. Gordon, J.G. Watkin, J.
Organomet. Chem. 577 (1999) 228.
[14] Y.M. Yao, Q. Shen, J. Sun, F. Xue, Acta Crystallogr., Sect. C 54
(1998) 625.
[15] Y.M. Yao, Q. Shen, J. Sun, Polyhedron 17 (1998) 519.
[16] Y. Li, X. Xu, L. Zhu, G. Lu, Chin. J. Appl. Chem. 5 (1987) 82.
[17] J.L. Atwood, W.E. Hunter, A.L. Wayda, W.J. Evans, Inorg.
Chem. 20 (1981) 4115.
[18] D.L. Clark, R.V. Hollis, B.L. Scott, J.G. Watkin, Inorg. Chem.
35 (1996) 667.
[43] J.Z. Jin, Z.S. Jin, W.Q. Chen, Jiegou Huaxue (Chin. J. Struct.
Chem.) 11 (1992) 204.
[19] G.B. Deacon, T. Feng, P.C. Junk, B.W. Skelton, A.H. White, J.
Chem. Soc., Dalton Trans. (1997) 1181.
[44] C.S. Day, V.W. Day, R.D. Ernst, S.H. Vollmer, Organometallics
1 (1982) 998.
[20] W.J. Evans, M.A. Greci, J.W. Ziller, J. Chem. Soc., Dalton
Trans. (1997) 3035.
[45] G.B. Deacon, P.I. Mackinnon, T.W. Hambley, J.C. Taylor, J.
Organomet. Chem. 259 (1983) 91.
[21] W.J. Evans, W.G. McClelland, M.A. Greci, J.W. Ziller, Eur. J.
Solid State Inorg. Chem. 33 (1996) 145.
[46] G.B. Deacon, T. Feng, S. Nickel, M.I. Ogden, A.H. White,
Aust. J. Chem. 45 (1992) 671.
[22] G.B. Deacon, T. Feng, P.C. Junk, B.W. Skelton, A.H. White,
Chem. Ber. 130 (1997) 851.
[47] C.T. Qian, B. Wang, D.L. Deng, C. Xu, X.Y. Sun, R.G. Ling,
Jiegou Huaxue (Chin. J. Struct. Chem.) 12 (1993) 18.
[48] M. Adam, X.F. Li, W. Oroschin, R.D. Fischer, J. Organomet.
Chem. 296 (1985) C19.
[49] L.L. Zhang, Y.M. Yao, Y.J. Luo, Q. Shen, J. Sun, Polyhedron
19 (2000) 2243.
[23] G.B. Deacon, T. Feng, C.M. Forsyth, A. Gitlits, D.C.R. Hock-
less, Q. Shen, B.W. Skelton, A.H. White, J. Chem. Soc., Dalton
Trans. (2000) 961.
[24] R.A. Andersen, D.H. Templeton, A. Zalkin, Inorg. Chem. 17
(1978) 1962.
[25] W.J. Evans, M.S. Sollberger, Inorg. Chem. 27 (1988) 4417.