Synthesis, reactivity and structural characterization of sodium and ytterbium complexes stabilized by a tridentate [N,N,O] Schiff base ligand

Article abstract of DOI:10.1016/j.poly.2007.10.025

A tridentate [N,N,O] Schiff base [3,5-Bu^t₂-2-(OH)-C₆H₂CH{double bond, long}N-8-C₉H₆N(LH)] was prepared, and the corresponding sodium and ytterbium complexes were synthesized and characterized. Reaction of LH with NaH in THF at room temperature afforded the sodium salt of the Schiff base as a dimer [{LNa(THF)}₂] (1). Complex 1 reacted with anhydrous YbCl₃ in THF, after workup, to give the monomeric ytterbium Schiff base dichloride complex, [LYbCl₂(DME)] (2). Complex 2 is a good precursor for the synthesis of the corresponding ytterbium derivatives. Reaction of complex 2 with 1 equiv. of NaCH₃C₅H₄ in THF gave the expected product [LYb(CH₃C₅H₄)Cl(THF)] (3) in a good isolated yield. Similar reaction of complex 2 with 2 equiv. of ArONa (ArO{double bond, long}OC₆H₃-Bu^t₂-2,6) in THF afforded the desired solvent-free ytterbium aryloxide [LYb(OAr)₂] (4). Complex 4 can also be prepared by the protolytic exchange reaction of LH with (ArO)₃Yb in a 1:1 molar ratio. All of these complexes were well characterized including X-ray structure determination.

Full text of DOI:10.1016/j.poly.2007.10.025

Available online at www.sciencedirect.com
Polyhedron 27 (2008) 709–716
www.elsevier.com/locate/poly
Synthesis, reactivity and structural characterization of sodium
and ytterbium complexes stabilized by a tridentate
[N,N,O] Schiff base ligand
a
a,
b
a
a,
*
Bang-Yu Li , Ying-Ming Yao *, Yao-Rong Wang , Yong Zhang , Qi Shen
a
Key Laboratory of Organic Synthesis of Jiangsu Province, Department of Chemistry and Chemical Engineering, Dushu Lake Campus,
Suzhou University, Suzhou 215123, PR China
b
College of Material Engineering, Suzhou University, Suzhou 215123, PR China
Received 16 October 2007; accepted 30 October 2007
Available online 4 December 2007
Abstract
A tridentate [N,N,O] Schiff base [3,5-But2-2-(OH)-C6H2CH@N-8-C9H6N(LH)] was prepared, and the corresponding sodium and
ytterbium complexes were synthesized and characterized. Reaction of LH with NaH in THF at room temperature afforded the sodium
salt of the Schiff base as a dimer [{LNa(THF)}2] (1). Complex 1 reacted with anhydrous YbCl3 in THF, after workup, to give the mono-
meric ytterbium Schiff base dichloride complex, [LYbCl2(DME)] (2). Complex 2 is a good precursor for the synthesis of the correspond-
ing ytterbium derivatives. Reaction of complex
2 with 1 equiv. of NaCH3C5H4 in THF gave the expected product
[LYb(CH3C5H4)Cl(THF)] (3) in a good isolated yield. Similar reaction of complex 2 with 2 equiv. of ArONa (ArO@OC6H3-But2-2,6)
in THF afforded the desired solvent-free ytterbium aryloxide [LYb(OAr)2] (4). Complex 4 can also be prepared by the protolytic
exchange reaction of LH with (ArO)3Yb in a 1:1 molar ratio. All of these complexes were well characterized including X-ray structure
determination.
ꢀ 2007 Published by Elsevier Ltd.
Keywords: Alkali metal; Lanthanide; Schiff base; Synthesis; Crystal structure
1. Introduction
opening polymerization of lactide and related cyclic esters
[5–7], as the materials for the potential applications in biol-
ogy, medicine as well as high-technology fields [8–12]. Gen-
erally, the tridentate Schiff base ligands with a flexible
donor atom, in comparison with the bidentate ligands,
can provide the protective shields for catalytically active
metal centers leading to a ‘‘more stable’’ active species
via the coordination of the additional donor atom. As a
result, the activity of the complex with a tridentate Schiff
base ligand is much higher than that of the complex with
a bidentate ligand [13,14]. However, anhydrous prepara-
tion and reactivity of lanthanide complexes with a triden-
tate Schiff base ligand still remains poorly explored.
Recently, monomeric lanthanocene aryloxide complexes
with a tridentate Schiff base ligand N-1-(ortho-methoxy-
phenyl) salicylideneamine was synthesized and structurally
characterized [15].
Over the past decade, significant efforts to explore
ligands other than traditional ancillary ligand cyclopenta-
dienyl set in organolanthanide chemistry have led to the
fruitful design of new non-lanthanocene complexes [1–4].
Of these alternatives, Schiff base ligands, that have hard
donor-atom frameworks, are attractive due to their stabil-
ity and the ease by which modified variations can be
obtained. Moreover, these lanthanide complexes are
known to serve as precatalysts in homogeneous catalysis,
such as asymmetric ring opening reaction of epoxide, ring
*
Corresponding authors. Tel.: +86 512 65880306; fax: +86 512
65880305 (Q. Shen).
E-mail addresses: yaoym@suda.edu.cn (Y.-M. Yao), qshen@suda.
edu.cn (Q. Shen).
0277-5387/$ - see front matter ꢀ 2007 Published by Elsevier Ltd.
doi:10.1016/j.poly.2007.10.025

710
B.-Y. Li et al. / Polyhedron 27 (2008) 709–716
Herein, we report the synthesis and molecular structure
1. Complex 1 has a dimeric structure, and two molecules
are connected together by two bridged oxygen atoms.
The molecules have approximate C2 symmetry. Each
sodium atom is five-coordinated with one oxygen atom,
two nitrogen atoms from one Schiff base ligand, one oxy-
gen atom from another ligand and one oxygen atom from
a THF molecule. The coordination geometry at sodium
atom can be described as a distorted trigonal bipyramid,
in which O(2), O(3) and N(1) can be considered to occupy
the equatorial positions, and O(1) and N(2) to occupy the
apical positions.
of a series of sodium and ytterbium complexes supported
by a tridentate Schiff base ligand including the complexes
of formulae [{LNa(THF)}2], [LYbCl2(DME)], [LYb-
(CH3C5H4)Cl(THF)] and [LYb(OAr)2], where L = [3,5-
Bct2-2-(O)C6H2CH@N-8-C9H6N]; ArO@OC6H3But2-2,6.
To our best knowledge, [LYbCl2(DME)] is the first struc-
turally characterized lanthanide dichloride complex stabi-
lized by Schiff base ligand.
2. Results and discussion
˚
The average Na–O(Ar) bond lengths of 2.279(4) A falls
2.1. Synthesis and characterization of [{LNa(THF)}2] (1)
in the range of Na–O(Ar) bond lengths in [Na4(sal-
phen)2(DME)2] (salphen = N,N0-o-phenylenebis(salicylide-
˚
Alkali metal salts of Schiff base are known to be the
starting reagents for the anhydrous preparation of lantha-
nide Schiff base complexes. It may be very informative to
know the structure of these starting reagents. However,
few structurally characterized Schiff base sodium com-
plexes were reported in the literatures [16,17]. Thus, the
sodium salt of the tridentate Schiff base HL, which was
synthesized by the condensation reaction of 8-aminoquino-
line with 3,5-di-tert-butyl-2-hydroxylbenzaldehyde [13],
was synthesized and characterized. Reaction of NaH with
HL in THF, after workup, afforded [{LNa(THF)}2] (1)
as yellow crystals as shown in Scheme 1. Complex 1 gave
satisfactory elemental analysis results, and its IR spectrum
shows the characteristic absorption bands of aromatic
rings in the region 1400–1600 cmꢀ1 (skeletal vibrations),
and of the C@N stretching vibration at 1613 cmꢀ1 and of
the phenolic C–O bond at 1242 cmꢀ1. The definitive molec-
ular structure was determined by single-crystal X-ray
diffraction.
neimine), 2.252(9)–2.291(9) A) [16] and [Na(18-crown-
6)(THF)2]2[Na2(OC6H4-2-C@NCH2CH2OH)]4 (2.221(3)–
˚
2.235(4) A) [17]. The Na–N(imine) bond lengths of
˚
2.407(3) (Na(1)–N(1)) and 2.388(3) A (Na(2)–N(3)) are
comparable with those found in [Na4(salphen)2(DME)2]
˚
(2.38(1) and 2.37(1) A) [16], but are smaller than those in
[Na(18-crown-6)(THF)2]2[Na2(OC6H4-2-C@NCH2CH2OH)]4
˚
(2.492(4) and 2.570(4) A) [17]. The bond lengths of Na–
˚
N(quinoline) are 2.550(3) (Na(1)–N(2)) and 2.403(3) A
(Na(2)–N(4)), respectively, which are larger than the Na–
N(imine) bond lengths.
2.2. Synthesis and characterization of ytterbium complexes
Although lanthanide dichloride complex supported by a
Schiff base ligand might be an important precursor for the
synthesis of the corresponding lanthanide derivatives via
metathesis reactions, no example of such lanthanide dichlo-
ride was reported up to date. Thus, we intend to synthesize
the ytterbium dichloride complex with the bulky tridentate
Schiff base group L as an ancillary ligand. Reaction of
The molecular structure of complex 1 is shown in Fig. 1,
and its selected bond lengths and angles are listed in Table
But
But
THF
N
N
O
OH
NaH
But
1/2
N
N
THF
Na
N
Na
O
N
THF
But
But
But
(1)
(ArO)3Yb
THF
YbCl3
THF/DME
But
But
N
But
N
N
N
O
Yb
MeCpNa
THF
But
But
N
But
N
2ArONa
THF
O
Yb
O
O
Yb
But
Cl
THF
But
Cl
O
Cl
O
O
But
But
(4)
(3)
(2)
Scheme 1.

B.-Y. Li et al. / Polyhedron 27 (2008) 709–716
711
Fig. 1. ORTEP diagram of complex 1 showing atom-numbering scheme. Thermal ellipsoids are drawn at the 20% probability level. Hydrogen atoms are
omitted for clarity.
Table 1
The molecular structure of complex 2 is shown in Fig. 2,
and the selected bond lengths and angles are provided in
˚
Selected bond distances (A) and angles (ꢁ) for complexes 1–4
1
2
3
4
Table 1. Complex 2 has a solvated monomeric structure,
and the central metal ytterbium atom is seven-coordinated
by one oxygen atom and two nitrogen atoms from one
Schiff base ligand, and two chlorine atoms and two oxygen
atoms from one DME molecule. The coordination geome-
try around ytterbium atom can be described as a distorted
pentagonal bipyramid, in which O(1), N(1), N(2) (from
Schiff base ligand), O(2) and O(3) (from DME) can be con-
sidered to occupy the equatorial positions with the sum of
the bond angles of 366ꢁ and Cl(1) and Cl(2) to occupy the
axis positions. The bond angle of Cl(1)–Yb–Cl(2) is slightly
distorted away from the ideal value of 180ꢁ to 162.29(3)ꢁ.
Bond distances
M(1)–O(1)
M(1)–O(2)
2.365(2)
2.274(2)
2.341(3)
2.407(3)
2.550(3)
2.115(2)
2.526(2)
2.417(2)
2.386(3)
2.470(3)
2.5934(8)
2.5654(9)
2.116(3)
2.450(3)
2.104(2)
2.089(2)
2.082(2)
2.359(3)
2.410(3)
M(1)–O(3)
M(1)–N(1)
M(1)–N(2)
Yb(1)–Cl(1)
Yb(1)–Cl(2)
Yb(1)–C(8)
Yb(1)–C(25)
Yb(1)–C(26)
Yb(1)–C(27)
Yb(1)–C(28)
Yb(1)–C(29)
2.400(3)
2.436(4)
2.594(1)
3.197(3)
2.675(5)
2.644(5)
2.636(5)
2.640(5)
2.645(4)
˚
The Yb–O(Ar) bond distance is 2.115(2) A, which is very
close to those observed in related ytterbium Schiff base
complexes [{2-OC6H4CH=(2,6-iPr2C6H3)}2YbCl(THF)]
Bond angles
O(1)–M(1)–O(2)
N(1)–M(1)–N(2)
N(1)–M(1)–O(2)
O(1)–M(1)–N(2)
N(1)–M(1)–O(1)
O(2)–M(1)–N(2)
89.83(8)
67.01(8)
108.36(9)
140.10(9)
73.11(8)
151.59(8)
66.40(9)
130.53(8)
135.70(9)
75.96(9)
72.18(8)
78.8(1)
67.5(1)
73.7(1)
142.4(1)
77.2(1)
79.2(1)
96.25(9)
68.50(9)
132.39(9)
135.22(9)
76.73(8)
87.45(9)
5
˚
(2.110(7) and 2.10(1) A) [6], [{(g -C5H5)Yb(l-OC20H20N2-
˚
O)}2(l-THF)(THF)] (2.15(2) A) [18]. The Yb–N(imine)
˚
bond distance is 2.386(3) A, which is slightly smaller than
those found in the ytterbium Schiff base complexes men-
tioned above. The Yb–N(quinoline) bond distance of
101.46(8)
˚
2.470(3) A is apparently larger than the Yb–N(imine) bond
distance, indicating the bond strength being somewhat
weaker than that of the Yb–N(imine) bond.
anhydrous YbCl3 with complex 1 in THF, after workup,
gave the first Schiff base lanthanide dichloride complex
[LYbCl2(DME)] (2) in high isolated yield from toluene/
DME mixed solvent as shown in Scheme 1. Complex 2
was characterized by elemental analysis and IR spectrum,
and its definitive molecular structure was provided by sin-
gle-crystal X-ray diffraction. Complex 2 is soluble in THF
and DME, and slightly soluble in toluene.
Generally, organolanthanide or organolanthanoid chlo-
rides are useful precursors for the synthesis of lanthanide
derivatives. Thus, the chloride substitution reactions of
complex 2 with other reagents were studied. The reaction
of complex 2 with 1 equiv. of NaCH3C5H4 in THF went
smoothly and, after workup, afforded the desired lantha-
nide complex [LYb(CH3C5H4)Cl(THF)] (3) in good

712
B.-Y. Li et al. / Polyhedron 27 (2008) 709–716
Fig. 2. ORTEP diagram of complex 2 showing atom-numbering scheme. Thermal ellipsoids are drawn at the 40% probability level. Hydrogen atoms are
omitted for clarity.
isolated yield (Scheme 1). Similar reaction of complex 2
with 2 equiv. of ArONa in THF, after workup, gave the
solvent-free ytterbium aryloxide [LYb(ArO)2] (4) as
orange-yellow crystals in high yield. Further study revealed
that complex 4 can also be conveniently prepared by the
direct protolytic exchange reaction of Schiff base LH with
Yb(ArO)3 in a 1:1 molar ratio in THF. The compositions
of complexes 3 and 4 were confirmed with elemental
analysis, and there are characteristic absorption bands of
the aryloxo group in their IR spectra. The definitive molec-
ular structures of complexes 3 and 4 were determined by
single-crystal structure analysis. Complexes 3 and 4 are
well soluble in THF and diethyl ether, and soluble in
toluene.
Crystals of complex 3 suitable for an X-ray diffraction
study were obtained from THF/Et2O solution at low tem-
perature. An ORTEP diagram of the molecular structure
of complex 3 is shown in Fig. 3, and the selected bond
lengths and angles are listed in Table 1. Complex 3 has a
monomeric structure. The ytterbium atom is coordinated
by two nitrogen atoms and one oxygen atom from the
Schiff base ligand, one Cp ring, one chlorine atom and
another oxygen atom from THF molecule to form a dis-
torted octahedral geometry, when the Cp ring was consid-
ered to occupy one coordination site. Two nitrogen atoms,
one oxygen atom of the Schiff base ligand and one chlorine
atom can be considered to occupy the equatorial positions
with the sum of the bond angles of 359.4ꢁ, and the centroid
Fig. 3. ORTEP diagram of complex 3 showing atom-numbering scheme. Thermal ellipsoids are drawn at the 30% probability level. Hydrogen atoms are
omitted for clarity. Disordered THF molecule is shown in two possible orientations.

B.-Y. Li et al. / Polyhedron 27 (2008) 709–716
713
Fig. 4. ORTEP diagram of complex 4 showing atom-numbering scheme. Thermal ellipsoids are drawn at the 30% probability level. Methyl groups of the
tert-butyl groups of aryloxides and hydrogen atoms are omitted for clarity.
of the Cp ring and the oxygen atom of the THF molecule
occupy the apical positions.
five-coordinated mononuclear lanthanide complexes bear-
ing Schiff base ligands in the literatures [20–23].
The Ln–C(Cp) bond distances range from 2.636(5) to
The Yb–O(Schiff base), Yb–N(imine) and Yb–N(quino-
line) bond distances in complex 4 are 2.104(2), 2.359(3) and
2.410(3) A, respectively, which are in accordance with the
˚
˚
2.675(5) A, giving the average 2.648(5) A, which is slightly
smaller than that in lanthanide cyclopentadienyl Schiff base
complexes [{(g5-C5H5)Ln(l-OC20H20N2O)}2(l-THF)(THF)]
˚
corresponding values in complexes 2 and 3. The bond dis-
˚
˚
˚
(Ln = Yb, 2.70(3) A [18]; Ln = Sm, 2.778 A [19]), and
tances of Yb–O(Ar) of 2.082(2) and 2.089(2) A, respec-
5
˚
[(g -C5H5)2Sm(OC14H13ON)] (2.723 A) [15], when the dif-
tively, compare well with the corresponding value in
˚
ference in ionic radius is considered. The Yb–O(Ar) bond
[(ArO)2YbCl(THF)2] (2.080(1) A) [24], but are slightly lar-
˚
distance of 2.116(3) A is well comparable with those values
ger than that in [{(DIPPh)2nacnac}Yb(ArO)Cl(THF)]
i
˚
˚
in [{2-OC6H4CH@NC6H3-Pr2-2,6}2YbCl(THF)] (2.107(7) A)
[2.024(2) A, (DIPPh)2nacnac=N,N-diisopropylphenyl-2,4-
[6], and other lanthanide Schiff base complexes mentioned
above. The Yb–N(imine) bond distance of 2.400(3) A is
pentanediimine anion] [25]. In addition, remote p interac-
tion of C(8) with Yb(1) was observed in complex 4. The
˚
˚
comparable with the Yb–N(quinoline) bond distance
bond distance of Yb(1)–C(8) is 3.197(3) A, which is compa-
˚
˚
(2.436(4) A), which is different from that in complex 2.
rable to those of 3.207(9) and 3.179(10) A for imidazoli-
˚
The Yb–Cl bond distance of 2.594(1) A is apparently larger
dine-bridged bis(phenolate) ytterbium dichloride [26], and
6
1
˚
than the corresponding value in [{2-OC6H4CH@N(2,6-
2.814(4) to 3.148(6) A for chelating g -,g -Ph–Yb bonding
i
˚
Pr2C6H3)}2YbCl(THF)] (2.497(2) A) [6], whereas this
in [{Yb(Odpp)3}2] (Odpp=2,6-diphenylphenolate) [27].
bond distance is comparable with that in complex 2.
Crystals of complex 4 suitable for X-ray diffraction were
obtained by recrystallization from toluene. The molecular
structure diagram with atom-numbering scheme is pre-
sented in Fig. 4, and its selected bond lengths and angles
are listed in Table 1. The ytterbium atom is coordinated
by one oxygen atom, two nitrogen atoms from the Schiff
base ligand and two oxygen atoms from two aryloxo
groups to form a five-coordinated highly distorted trigonal
bipyramidal geometry. O(2), O(3) and N(1) can be consid-
ered to occupy the equatorial positions with the sum of the
angles of 355.47ꢁ, and O(1) and N(2) to occupy the apical
positions. Usually, lanthanide Schiff base complexes have
high coordination numbers (>6) via oligomerisation or sol-
vent stabilization, these is few structurally characterized
3. Conclusion
A bulky tridentate Schiff base was prepared, and this
compound can be used as an ancillary ligand for a series
of sodium and ytterbium complexes. The Schiff base
reacted with NaH to give the corresponding sodium salt
as a dimeric complex, which reacted with anhydrous YbCl3
to produce the first structurally characterized soluble ytter-
bium dichloride bearing Schiff base ligand. It was found
that this ytterbium dichloride can be used as a useful pre-
cursor for the synthesis of the corresponding ytterbium
derivatives by direct salt metathesis reactions. All of these
complexes were well characterized, and their molecular
structures were determined by X-ray diffraction.

714
B.-Y. Li et al. / Polyhedron 27 (2008) 709–716
4. Experimental
24.87%. IR (KBr, cmꢀ1): 2956(m), 2928(m), 1613(s),
1535(m), 1498(m), 1427(m),1319(m), 1234(vs), 1158(vs),
833(m),787(m), 633(m), 556(m), 509(s). The crystals suit-
able for an X-ray crystal structure determination were
obtained by recrystallization from THF–DME solution
at room temperature.
4.1. Materials and methods
All of the manipulations described below were per-
formed under an argon atmosphere, using the standard
Schlenk techniques. Solvents were dried and freed of oxy-
gen by refluxing over sodium or sodium benzophenone
ketyl and distilled under argon prior to use. Schiff base
ligand HL [3,5-Bu2t -2-(OH)C6H2CH@N-8-C9H6N] [13],
anhydrous YbCl3 [28] and Yb(OAr)3 [29] were prepared
according to the literature methods. NaCH3C5H4 was pre-
pared by the reaction of CH3C5H5 with sodium in THF.
The other reagents were purchased from Acros and used
as received without further purification. Metal analyses
were carried out using complexometric titration. Carbon,
hydrogen, and nitrogen analyses were performed by direct
combustion on a Carlo Erba-1110 instrument; Quoted data
are the average of at least two independent determinations.
IR spectra were recorded on a Nicolet-550 FTIR spectrom-
eter as KBr pellets. 1H NMR spectrum was obtained on an
INOVA-400 MHz apparatus. The uncorrected melting
points of crystalline samples in sealed capillaries (under
argon) are reported as ranges.
4.4. Synthesis of [(CH3C5H4)YbLCl(THF) Æ THF]
(3 Æ THF)
A Schlenk flask was charged with complex 2 (0.69 g,
1.0 mmol) and THF (20 mL).
A THF solution of
NaCH3C5H4 (1.0 mL, 1.0 mmol) was added by syringe.
The reaction mixture was stirred overnight at room tem-
perature. After removed the volatiles in vacuum, the yellow
residue was extracted with Et2O, and NaCl was removed
by centrifugation. Orange-yellow crystals were obtained
at room temperature, (0.47 g, 60%), m.p.: 158–160 ꢁC
(dec). Anal. Calc. for C38H50ClN2O3Yb (3 Æ THF): C,
57.68; H, 6.37; N, 3.54; Yb, 21.87. Found: C, 57.45; H,
6.63; N, 3.57; Yb, 21.51%. IR (KBr, cmꢀ1): 2956(s),
2905(m), 1608 (s), 1534(m), 1503(m), 1463(m), 1425(m),
1330(m), 1223(vs), 1159(vs), 1086(m), 835(m), 792(m),
506(s).
4.2. Synthesis of [{NaL(THF)}2] (1)
4.5. Synthesis of [LYb(OAr)2] (4)
A solution of HL (1.80 g, 5.0 mmol) in THF (20 mL)
was added dropwise to a NaH suspension (1.5 equiv.) in
THF at room temperature. The mixture was stirred for
14 h, and then was filtered. The resulting dark red solution
was concentrated. Yellow crystals were obtained from the
mixture of THF and toluene (6:1) at room temperature
in a few days (3.87 g, 85%), m.p.: 279–281 ꢁC (dec). Anal.
Calc. for C56H70N4Na2O4: C, 73.97; H, 7.76; N, 6.16.
Found: C, 73.58; H, 7.95; N, 5.76%. IR (KBr pellet,
cmꢀ1): 2956(vs), 2909(m), 2871(m), 1613(vs), 1458(vs),
1389(m), 1366(m), 1242(s), 1157(s), 1088(w), 1057(w),
1026(w), 980(w), 880(m), 826(m), 795(m), 640(w), 502(m).
1H NMR (400 MHz, C6H6): 8.50–8.48 (m, 1H, C9H6N),
8.43 (s, 1H, CH@N), 7.43–7.40 (m, 1H, C9H6N), 7.30–
7.25 (m, 3H, C9H6N), 6.98 (d, 2H, J = 2.6 Hz, C6H2),
6.65–6.60 (m, 1H, C9H6N), 4.06 (m, 4H, THF), 2.09 (m,
4H, THF), 1.79 (s, 9H, C(CH3)3), 1.33 (s, 9H, C(CH3)3).
4.5.1. Method A
A Schlenk flask was charged with complex 2 (0.69 g,
1.0 mmol) and THF (20 mL). A THF solution of NaOAr
(2.0 mL, 2.00 mmol) was added by syringe. The reaction
mixture was stirred overnight at room temperature. After
removed the volatiles in vacuum, the yellow residue was
extracted with toluene, and the precipitate was removed
by centrifugation. Complex 4 was obtained as yellow crys-
tals at room temperature (0.56 g. 60%), m.p.: 189–191 ꢁC
(dec). Anal. Calc. for C52H69N2O3Yb: C, 66.22; H, 7.37;
N, 2.97; Yb, 18.35. Found: C, 66.38; H, 7.53; N, 2.91;
Yb, 18.27%. IR (KBr, cmꢀ1): 2956(vs), 2909(s), 2871(s),
1613(s), 1528(s), 1505(s), 1466(s), 1428(vs), 1235(s),
1196(s), 1165(s), 1088(m), 1065(m), 833(m), 795(m),
748(m), 656(w), 594(w), 509(w).
4.5.2. Method B
Yb(OAr)3 (0.81 g, 1.0 mmol) in toluene was added drop-
wise to a THF solution of HL (0.36 g, 1.0 mmol) (30 mL).
The reaction mixture was stirred at room temperature for
12 h, and then concentrated in vacuum. Orange-yellow
crystals obtained after 4 days at room temperature,
(0.66 g. 70%).
4.3. Synthesis of [LYbCl2(DME)] (2)
A THF solution (10 mL) of complex 1 (0.91 g,
1.0 mmol) was added to a suspension of anhydrous YbCl3
(0.56 mg, 2.0 mmol) in THF (20 mL) at room temperature.
After the solution was stirred overnight, the precipitate was
separated from the reaction mixture by centrifugation. The
solution was concentrated, and then DME (0.5 mL) was
added. Yellow crystals were obtained at room temperature
in a few days (1.10 g, 80%), m.p.: 266–268 ꢁC (dec). Anal.
Calc. for C28H37Cl2N2O3Yb: C, 48.49; H, 5.38; N, 4.04;
Yb, 24.95. Found: C, 48.87; H, 5.67; N, 3.98; Yb,
4.6. X-ray structures determination
Suitable single crystals of complexes 1–4 were sealed in a
thin-walled glass capillary for determining the single-crys-
tal structure. Intensity data were collected with a Rigaku
Mercury CCD area detector in x scan mode using Mo

B.-Y. Li et al. / Polyhedron 27 (2008) 709–716
715
Table 2
Details of the crystallographic data and refinements for complexes 1–4
Compound
1 Æ THF
2
3 Æ THF
4
Formula
Fw
C60H78N4Na2O5
981.24
C28H37Cl2N2O3Yb
693.54
C38H50ClN2O3Yb
791.29
C52H69N2O3Yb
943.13
T (K)
153(2)
193(2)
193(2)
193(2)
Crystal system
monoclinic
P21/c
12.824(1)
24.651(2)
18.352(2)
monoclinic
P21/c
13.680(1)
21.014(1)
10.5822(9)
monoclinic
P21/c
13.509(2)
15.101(1)
18.660(2)
triclinic
ꢀ
Space group
P1
˚
a (A)
10.5557(6)
14.1107(9)
16.980(1)
84.492(4)
84.294(4)
76.306(3)
2438.2(3)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
107.192(2)
105.830(3)
109.404(3)
3
˚
V (A )
5542.0(10)
4
1.176
0.087
2112
2926.8(4)
4
1.574
3.408
1388
3590.5(7)
4
1.464
2.716
1612
Z
Dcalc (g/cmꢀ3
)
1.285
1.959
978
l (mmꢀ1
F(000)
)
Crystal size (mm)
2h Range (ꢁ)
0.45 · 0.37 · 0.20
50.7
54227
10128
7968
653
1.129
0.0778
0.1677
0.55 · 0.30 · 0.28
50.7
28349
5351
5105
340
1.066
0.0233
0.0569
0.25 · 0.20 · 0.12
50.7
35016
6566
5815
414
1.149
0.0369
0.0765
0.78 · 0.42 · 0.20
50.7
23349
8818
8272
542
1.108
0.0316
0.0757
Reflections collected
Independent reflections
Reflections with I P 2.0r(I)
Parameters refined
Goodness-of-fit
R
wR
˚
Ka radiation (k = 0.71070 A). The diffracted intensities
were corrected for Lorentz polarization effects and empiri-
cal absorption corrections. Details of the intensity data col-
lection and crystal data are given in Table 2.
this article can be found, in the online version, at
doi:10.1016/j.poly.2007.10.025.
References
The structures were solved by direct methods and
refined by full-matrix least-squares procedures based on
[1] K. Dehnicke, A. Greiner, Angew. Chem., Int. Ed. 42 (2003) 1340.
[2] W.E. Piers, J.J.H. Emslie, Coord. Chem. Rev. 131 (2002) 233.
[3] H.C. Aspinall, Chem. Rev. 102 (2002) 1807.
[4] P.W. Roesky, Chem. Soc. Rev. 29 (2000) 335.
[5] M.O. Tina, W.C. Geoffrey, J. Am. Chem. Soc. 121 (1999) 4072.
[6] L.B. Yu, Y.M. Yao, Q. Shen, J. Zhang, L.X. Wu, L. Ye, Chin. J.
Chem. 1 (2003) 442.
2
jFj . All of the non-hydrogen atoms were refined anisotrop-
ically. All of the hydrogen atoms were held stationary and
included in the structure factor calculation in the final stage
of full-matrix least-squares refinement. The structures were
solved and refined using SHELEXL-97 programs.
[7] S.A. Schuetz, C.M. Silvernail, C.D. Incarvito, A.L. Rheingold, J.L.
Clark, V.W. Day, J.A. Belot, Inorg. Chem. 43 (2004) 6203.
[8] V. Patroniak, A.R. Stefankiewicz, J.M. Lehn, M. Kubicki, M.
Hoffmann, Eur. J. Inorg. Chem. (2006) 144.
[9] R.D. Archer, H.Y. Chen, L.C. Thompson, Inorg. Chem. 37 (1998)
2089.
[10] R.D. Jones, D.A. Summerville, F. Basalo, Chem. Rev. 79 (1979) 139.
[11] R. Rodriguez-Cortinas, F. Avecilla, C. Platas-Iglesias, D. Imbert, J.-
C.G. Bunzli, A. Blas, T. Rodriguez-Blas, Inorg. Chem. 41 (2002)
5336.
[12] M. Gonza’lez-Lorenzo, C. Platas-Iglesias, F. Avecilla, C.F.G.C.
Geraldes, D. Imbert, J.-C.G. Bunzli, A. Blas, T.R. Blas, Inorg. Chem.
42 (2003) 6946.
Acknowledgements
The financial support from the National Natural Science
Foundation of China (Grants 20632040 and 20771078),
the Natural Science Foundation of Jiangsu province
(BK2007505), the Major Basic Research Project of the Nat-
ural Science Foundation of the Jiangsu Higher Education
Institutions (07KJA15014), and Key Laboratory of Organic
Synthesis of Jiangsu Province is gratefully acknowledged.
[13] P.A. Cameron, V.C. Gibson, C. Redshaw, J.A. Segal, A.J.P. White,
D.J. Williams, J. Chem. Soc., Dalton Trans. (2002) 415.
[14] R.K. O’Reilly, V.C. Gibson, A.J.P. White, D.J. Williams, J. Am.
Chem. Soc. 125 (2003) 8450.
[15] M. Yousaf, Q.C. Liu, J.L. Huang, Y.L. Qian, A.S.-C. Chan, Inorg.
Chem. Commun. 3 (2000) 105.
[16] E. Solari, S. De Angelis, C. Floriani, A. Chiesi-Villa, C. Rizzoli, J.
Chem. Soc., Dalton. Trans. (1991) 2471.
[17] R. Fisher, H. Gorls, D. Walther, Z. Anorg. Allg. Chem. 630 (2004)
1387.
Appendix A. Supplementary material
CCDC 662844, 662845, 662846 and 662847 contain the
supplementary crystallographic data for 1, 2, 3 and 4.
These data can be obtained free of charge via www.ccdc.
ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
[18] Q.C. Liu, M.X. Ding, J. Organomet. Chem. 553 (1998) 179.

716
B.-Y. Li et al. / Polyhedron 27 (2008) 709–716
[19] Q.C. Liu, M.X. Ding, Y.H. Lin, Y. Xing, Polyhedron 17 (1998)
555.
[24] Y.M. Yao, Q. Shen, Y. Zhang, M.Q. Xue, J. Sun, Polyhedron 20
(2001) 3201.
[20] Y.P. Cai, H.Z. Ma, B.S. Kang, C.Y. Su, W. Zhang, J. Sun, Y.L.
Xiong, J. Organomet. Chem. 628 (2001) 99.
[21] P. Blech, C. Floriani, A. Chiesivilla, C. Guastini, J. Chem. Soc.,
Dalton Trans. (1990) 3557.
[22] S.A. Schuetz, V.W. Day, A.L. Rheingold, J.A. Belot, J. Chem. Soc.,
Dalton Trans. (2003) 4303.
[25] Y. Zhang, Y.M. Yao, Y.J. Luo, Q. Shen, Y. Cui, K.B. Yu,
Polyhedron 22 (2003) 1241.
[26] X.P. Xu, Y.M. Yao, Y. Zhang, Q. Shen, Inorg. Chem. 46 (2007) 3743.
[27] G.B. Deacon, S. Nickle, P.I. Mackinnon, E.R.T. Tiekink, Aust. J.
Chem. 43 (1990) 1245.
[28] M.D. Taylor, C.P. Carter, J. Inorg. Nucl. Chem. 24 (1962) 387.
[29] P.B. Hitchcock, M.F. Lappert, R.G. Smith, Inorg. Chim. Acta 139
(1987) 183.
[23] W.J. Evans, C.H. Fujimoto, J.W. Ziller, Polyhedron 21 (2002)
1683.