Synthesis, characterization and structural diversity of lanthanide chlorides supported by the β-diketiminate ligand [{(2,6-Me 2C6H3)NC(Me)}2CH]-

Article abstract of DOI:10.1016/j.ica.2004.03.022

Reactions of the β-diketiminate lithium salt L²Li [L ²={(2,6-Me₂C₆H₃)NC(Me)} ₂CH] with anhydrous LnCl₃ (Ln=Yb, Sm, Nd) in 1:1 molar ratio in THF afforded the new β-diketiminate l

Full text of DOI:10.1016/j.ica.2004.03.022

Inorganica Chimica Acta 357 (2004) 3173–3180
www.elsevier.com/locate/ica
Synthesis, characterization and structural diversity of
lanthanide chlorides supported by the b-diketiminate ligand
[{(2,6-Me2C6H3)NC(Me)}2CH]ꢀ
a
a,
a
a
b
Zhen-Qin Zhang , Ying-Ming Yao *, Yong Zhang , Qi Shen , Wing-Tak Wong
a
Key Laboratory of Organic Synthesis, Department of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215006, PR China
b
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China
Received 27 October 2003; accepted 13 March 2004
Available online 12 April 2004
Abstract
Reactions of the b-diketiminate lithium salt L2Li [L2 ¼ {(2,6-Me2C6H3)NC(Me)}2CH] with anhydrous LnCl3 (Ln ¼ Yb, Sm, Nd)
in 1:1 molar ratio in THF afforded the new b-diketiminate lanthanide complexes L2LnCl(THF)(l-Cl)2Li(THF)2 (Ln ¼ Yb (1), Sm
(2), Nd (3)). Recrystallization of complexes 1–3 from toluene gave the neutral complexes L2LnCl2(THF)2 (Ln ¼ Yb (4), Sm (5), Nd
(6)). Recrystallization of complexes 4 and 5 in hot toluene for two times gave the dinuclear complexes L2ClLn(l-Cl)3LnL2(THF)
(Ln ¼ Yb (7), Sm (8)). Treatment of the mother liquor of complex 2 in hot toluene for three times gave the novel trinuclear complex
L2SmCl(l-Cl)3SmL2(l-Cl)Li(L2H)(THF) (9). Each of these complexes was well characterized, while complexes 3, 7 and 9 have been
characterized by X-ray diffraction structure determination.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Lanthanide complexes; b-Diketiminate ligand; Synthesis; Crystal structure
1. Introduction
Recently, we became interested in studying the syn-
thesis and reactivity of organolanthanide complexes
supported by the b-diketiminate ligands [15–19], and
found that the room-temperature reaction of anhydrous
YbCl3 with one equiv. of lithium b-diketiminate in
THF, followed by crystallization from toluene, results in
the isolation of monomeric bis-THF adducts LYbCl2-
(THF)2 [L ¼ {PhNC(Me)}2CH (L1), {(2,6-Me2C6H3)-
NC(Me)}2CH (L2), {(2,6-Pr2i C6H3)NC(Me)}2CH (L3),
b-Diketiminates are important spectator ligands by
virtue of their strong binding to metals, their tunable
and extensive steric demands and their diversity of
bonding modes [1]. The utilization of b-diketiminates in
organolanthanides or organolanthanoids is of sub-
stantial current interest, and a variety of lanthanide
complexes have been reported [2–22], and some of which
have been shown interested reactivity [8,11,13,17]. Al-
though there are big ionic radii for lanthanide elements,
the b-diketiminate lanthanide dichlorides can be con-
veniently synthesized, due to the steric bulkiness of the
b-diketiminate ligands, which serve as important pre-
cursors for further transformation. However, little is
known about the structural details of these key species
[3,9,16].
(4-ClC6H4)NC(Me)CHC(Me)N(C6H3Pri2-2,6)
(L4)].
However, recrystallization of L3YbCl2(THF)2 from hot
toluene solution for two times gave the unexpected di-
nuclear b-diketiminate ytterbium dichlorides with a rare
triple chlorine bridge in the molecule [15]. Generally, the
central metals in dimeric lanthanide halides are con-
nected by one or two halogen bridge(s). Only a few
examples of crystallographically characterized multiple
halogen bridges between two lanthanide atoms are those
found in lanthanide clusters [23]. In order to elucidate
the structural diversity of b-diketiminate lanthanide
dichlorides, we used the b-diketiminate ligand L2 as
* Corresponding author. Tel.: +86-512-6511-2513; fax: +86-512-651-
12371 (Y.-M. Yao).
E-mail address: yaoym@suda.edu.cn (Y.-M. Yao).
0020-1693/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.03.022

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Z.-Q. Zhang et al. / Inorganica Chimica Acta 357 (2004) 3173–3180
an ancillary ligand and synthesized a series of the
b-diketiminate lanthanide dichlorides, and found that
crystallization conditions have significant effect on the
structure of the lanthanide dichlorides obtained. Here,
we report the synthesis and characterization of these
complexes and the crystal structures of the dinuclear
complexes L2NdCl(THF)(l-Cl)2Li(THF)2 (3), L2ClYb
(l-Cl)3YbL2(THF) (7), and the trinuclear complex
L2SmCl(l-Cl)3SmL2(l-Cl)Li(L2H)(THF) (9).
5 and 6 are also consistent with the proposed stoichi-
ometry of L2LnCl2(THF)2 (Ln ¼ Sm (5), Nd (6)), and
their infrared spectra showed absorptions characteristic
of the b-diketiminate ligand. Blue crystals of 6 were
obtained in concentrated toluene solution and analyzed
by X-ray diffraction. Although an adequate data set was
1
obtained, structure solution has not yet been possible.
After further recrystallization of complex 4 from hot
toluene for two times, the color of the solution changed
from red to violet. The dark violet crystals of 7 were
obtained from concentrated toluene solution, which was
characterized to be part of coordinated THF lost
(Scheme 3). Structural analysis of complex 7 reveals that
it has a dinuclear structure with a triple chlorine bridge,
L2YbCl(l-Cl)3YbL2(THF) (see below). Similar recrys-
tallization of complex 5 from toluene produced the or-
ange red microcrystals (8). Elemental analysis and IR
spectrum reveal that complex 8 is the analogue of com-
plex 7. The effort to obtain crystals suitable for X-ray
structure studies was unsuccessful. Treatment of the
mother liquor of complex 2 as described above gave the
orange red crystals suitable for structure analysis in
extremely small yield. However, elemental analysis and
X-ray structure study demonstrate that this complex is
not the complex 8, but a new complex L2SmCl(l-
Cl)3SmL2ClLi(L2H)(THF) (9). It is quite unexpected
that a lithium chloride incorporated with a neutral b-
diketimine molecule is coordinated to one samarium
atom via a single chlorine bridge. The formation of
complex 9 may be attributed to the presence of excess of
b-diketimine molecule in the reaction system, which
coordinates to the lithium atom and increases the solu-
bility of lithium chloride in toluene. The sparing solu-
bility of complex 6 in toluene prevents its further
recrystallization.
2. Results and discussion
2.1. Synthesis
One equiv. of L2Li was added to a slurry of LnCl3
(Ln ¼ Yb, Sm, Nd) in THF–hexane mixed solvent at
room temperature, the color of the solution gradually
changed to red (for Yb), yellow (for Sm) or blue (for
Nd), respectively. After work up, the microcrystals of 1-
3 were obtained from concentrated THF solution in
high yield. The compositions of complexes 1–3 were
established as L2LnCl(THF)(l-Cl)2Li(THF)2 (Ln ¼ Yb
(1), Sm (2), Nd (3)) by elemental analyses (C, H, N and
Ln) and crystal structure determination for complex 3
(Scheme 1). The IR spectra of complexes 1–3 exhibited
strong absorptions near 1555 cmꢀ1, which were consis-
tent with partial C@N double-bond character [24].
By recrystallization of complexes 1–3 from hot tolu-
ene, after work up, the microcrystals of complexes 4–6
were obtained in good yield (Scheme 2). Lithium anal-
ysis shows that no lithium exists in these complexes. The
results by elemental analysis and IR spectrum demon-
strate that complex
4
is the known complex
L2YbCl2(THF)2 that we have previously synthesized by
direct method [17]. Elemental analysis data of complexes
Complexes 1–6 are slightly sensitive to air and
moisture, and the crystals can be exposed in air for a few
hours without apparent decomposition; however, com-
plexes 7–9 are very sensitive to air and moisture.
Ar
Ar
THF
Cl
N
N
N
N
THF
THF
THF
+
LnCl3
Li
Ln
Li
2.2. Crystal structure determination
Cl
Cl
Ar
Ar
ORTEP diagram depicting the molecular structure of
complex 3 is shown in Fig. 1, the selected bond lengths
and bond angles are given in Table 1. As shown in
Fig. 1, complex 3 is a dinuclear neodymium–lithium
complex with two chlorine bridges; this is different from
the b-diketiminate lanthanide dihalides reported in the
literature, in which all of them have neutral structure in
solid state. The LNd moiety is bonded through two
chlorine bridges to a lithium cation, which in turn is
bonded to two oxygen atoms of two THF molecules.
Ar =
Ln = Yb (1), Sm (2), Nd (3)
Scheme 1.
Ar
Ar
TH F
TH F
N
N
N
Cl
TH F
TH F
Cl
Cl
TH F
toluene
Ln
Ln
Li
Cl
N
Cl
Ar
Ar
Ln = Yb (4), Sm (5), Nd (6)
1
The crystal data for complex 6: monoclinic, space group P21=n,
ꢀ
a ¼ 20:718ð9Þ, b ¼ 14:008ð6Þ, c ¼ 20:728ð9Þ A, b ¼ 93:799ð4Þ°,
3
ꢀ
Scheme 2.
V ¼ 6002ð4Þ A .

Z.-Q. Zhang et al. / Inorganica Chimica Acta 357 (2004) 3173–3180
3175
Ar
Ar
Ar
Ln
THF
THF
Cl
Cl
THF
N
N
N
N
N
N
Cl
toluene
Ln
Ln
Cl
Cl
Cl
Ar
Ar
Ar
Ln = Yb (7), Sm (8)
Ar
Ar
Cl
N
N
N
Ar
Cl
THF
Cl
Sm
Sm
N
N
Cl
Cl
THF
THF
toulene
L2H
N
Sm
Li
Cl
THF
Ar
Cl
Ar
Li
Cl
Ar
Ar
Ar
N
N
(9)
Scheme 3.
Table 1
ꢀ
Selected bond lengths (A) and angles (°) in complex 3
Bond lengths
Nd(1)–N(1)
Nd(1)–O(1)
Nd(1)–Cl(2)
Li(1)–Cl(1)
Li(1)–O(2)
N(1)–C(1)
C(1)–C(2)
2.445(5)
2.497(4)
2.783(2)
2.38(1)
Nd(1)–N(2)
Nd(1)–Cl(1)
Nd(1)–Cl(3)
Li(1)–Cl(2)
Li(1)–O(3)
N(2)–C(3)
C(2)–C(3)
2.422(5)
2.746(2)
2.664(2)
2.36(1)
1.91(2)
1.324(7)
1.382(9)
1.92(1)
1.335(7)
1.391(9)
Bond angles
O(1)–Nd(1)–N(1)
O(1)–Nd(1)–N(2)
O(1)–Nd(1)–Cl(2)
N(1)–Nd(1)–Cl(3)
N(1)–Nd(1)–Cl(2)
N(2)–Nd(1)–Cl(2)
91.1(2)
167.2(2)
85.0(1)
93.7(1)
175.1(1)
106.7(1)
N(1)–Nd(1)–N(2)
O(1)–Nd(1)–Cl(3)
O(1)–Nd(1)–Cl(1)
N(2)–Nd(1)–Cl(3)
N(1)–Nd(1)–Cl(1)
N(2)–Nd(1)–Cl(1)
76.9(2)
89.0(1)
81.5(1)
96.1(1)
96.2(1)
95.3(1)
Cl(2)–Nd(1)–Cl(3) 89.33(5)
Cl(1)–Nd(1)–Cl(3) 166.38(5)
Cl(1)–Nd(1)–Cl(2) 80.22(5)
Cl(1)–Li(1)–Cl(2) 97.6(5)
asymmetrically coordinated to the central metal. The
ꢀ
Fig. 1. Molecular structure of complex 3. Thermal ellipsoids are drawn
at the 50% probability level.
average Nd–N bond length of 2.433(7) A is comparable
with the corresponding bond lengths in L2YbCl2(THF)2
[17], L3ScCl2(THF) [7], and L4SmCl2(THF)2 [16], but
apparently longer than that in L1SmCl2(THF)2 [16],
when the difference in ionic radii is considered [25]. It is
reasonable to ascribe these differences in bond parame-
ters to the less steric congestion in the latter due to no
substituent on the arene ring of the ligand. The bond
lengths of Nd–Cl(1) and Nd–Cl(2) are apparently longer
than that of Nd–Cl(3), due to the formation of bridge
bonds. The Nd–C(1,2,3) distances are quite long, sug-
gesting a negligible p contribution to the b-diketimi-
nate–Nd bonding in this complex. The bond distances of
C(1)–C(2), C(2)–C(3), N(1)–C(1) and N(2)–C(3) lie in-
termediate between the corresponding single- and dou-
ble-bond distances (see Table 1), which suggest
The Nd ion displays a distorted octahedral geometry
defined by the two nitrogen atoms of the chelating
bidentate b-diketiminate ligand, three chlorine atoms,
and one oxygen atom from THF molecule (Cl(1), Cl(3),
O(1) and N(2) form a plane, N(1) and Cl(2) serve as two
vertexes), while Li ion adopts a distorted tetrahedral
geometry formed by two chlorine ligands and two oxy-
gen atoms of THF molecules.
The b-diketiminate ligand is symmetrically coordi-
nated to the neodymium atom, which is similar to those
found in L4SmCl2(THF)2 [16] and L1GdBr2(THF)2 [3],
but different from those in L1SmCl2(THF)2 [16] and
L3ScCl2(THF) [7], in which two nitrogen atoms are

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Z.-Q. Zhang et al. / Inorganica Chimica Acta 357 (2004) 3173–3180
significant delocalization within the p-system of b-dik-
etiminate backbone.
two ytterbium centers is similar (six-coordinate distorted
octahedral). The Yb(1) atom is coordinated by two ni-
trogen atoms of the b-diketiminate ligand, and one
terminal chlorine atom and three bridged chlorine at-
oms; the Yb(2) center is coordinated by two nitrogen
atoms, and three bridged chlorine atoms and one oxy-
gen atom of THF molecule.
The backbone of the ligand (NC3N) and ytterbium
atom form a stable six-membered ring, which adopts a
boat conformation with C(3) and Yb(1) lying 0.14 and
The molecular structure of complex 7 is shown in
Fig. 2, and the selected bond lengths and angles are
listed in Table 2. Complex 7 has a dinuclear structure in
the solid state. The interesting feature of this structure is
that the two ytterbium centers are triply chlorine-
bridged. Moreover, the coordination environment
around the two ytterbium centers in complex 7 is in-
equivalent, although the coordination geometry around
ꢀ
0.69 A out of the N(1)C(2)C(4)N(2) plane; and C(24)
ꢀ
and Yb(2) lying 0.10 and 0.62 A out of the N(3)C(23)-
C(25)N(4) plane, respectively. The dihedral angle be-
tween these planes is 106.56°, which indicates that the
orientation of the two b-diketiminate ligands is ap-
proximately perpendicular. The orientation of the arene
rings relative to the NC2N plane is also approximately
perpendicular (the average dihedral angles between the
arene rings and the NC2N planes range from 80.84° to
91.73°). This disposition can release the steric repulsion
among the methyl substituents on the arene rings and
the backbone of the b-diketiminate.
Two b-diketiminate ligands are symmetrically coor-
dinated to Yb(1) and Yb(2), respectively, and the Yb–N
ꢀ
bond distances range from 2.278(4) to 2.286(4) A, which
is comparable with those found in L3YbCl(l-
Cl)3YbL3(THF) [15] and L2YbCl2(THF)2 [17]. The
Yb(1)–Cl(1) and Yb(2)–O(1) bond lengths are also
comparable with those in L3YbCl(l-Cl)3YbL3(THF)
[15], but apparently shorter than the corresponding
bond lengths in L2YbCl2(THF)2 [17], although the latter
has monomeric structure. The three chlorine bridges in
complex 7 are asymmetrical. The averaged Yb(1)–
Fig. 2. Molecular structure of complex 7. Thermal ellipsoids are drawn
at the 20% probability level. Hydrogen atoms are omitted for the sake
of clarity.
ꢀ
ꢀ
Cl(2,3,4) bond length of 2.722(1) A is ca. 0.07 A longer
than that of Yb(2)–Cl(2,3,4), which is well comparable
with that found in L3YbCl(l-Cl)3YbL3(THF) [15].
There is an expected pattern of delocalization within the
p-system of the b-diketiminate ligand.
Table 2
ꢀ
Selected bond lengths (A) and angles (°) in complex 7
Bond lengths
The molecular structure of complex 9 is shown in
Fig. 3, and the selected bond lengths and angles are
listed in Table 3. Complex 9 is a trinuclear species; there
is also a triple chlorine bridge between two samarium
atoms in complex 9. The apparent difference between
complex 9 and 7 is that one lithium chloride incorpo-
rated with a neutral b-diketimine and a THF molecule
in place of the THF is coordinated to Sm(2) in complex
9. The coordination geometry around the samarium
atom also resembles that in complex 7 and the coordi-
nation environment around samarium atoms in complex
9 is still inequivalent. By comparison of the molecular
structures of complexes 7 and 9 and the analogous
complex L3YbCl(l-Cl)3YbL3(THF) [15], it seems that
the formation of triple chlorine bridge in b-diketiminate
lanthanide dichlorides is popular under the lack of co-
ordinated solvent. This may be attributed to the struc-
tural property of the b-diketiminate ligands. Due to the
Yb(1)–N(1)
Yb(1)–N(2)
Yb(1)–Cl(1)
Yb(1)–Cl(2)
Yb(1)–Cl(3)
Yb(1)–Cl(4)
N(1)–C(2)
2.278(4)
2.284(4)
2.496(1)
2.701(1)
2.720(1)
2.745(1)
1.328(7)
1.417(8)
1.392(8)
1.325(7)
3.648
Yb(2)–N(3)
Yb(2)–N(4)
Yb(2)–O(1)
Yb(2)–Cl(2)
Yb(2)–Cl(3)
Yb(2)–Cl(4)
C(23)–N(3)
C(23)–C(24)
C(24)–C(25)
C(25)–N(4)
2.286(4)
2.285(4)
2.273(4)
2.662(1)
2.671(1)
2.624(1)
1.332(7)
1.401(9)
1.401(9)
1.336(7)
C(2)–C(3)
C(3)–C(4)
C(4)–N(2)
Yb(1)–Yb(2)
Bond angles
N(1)–Yb(1)–N(2)
N(1)–Yb(1)–Cl(1)
80.3(2)
101.2(1)
N(3)–Yb(2)–N(4)
N(3)–Yb(2)–O(1)
O(1)–Yb(2)–Cl(2)
81.3(2)
93.9(2)
84.3(1)
Cl(1)–Yb(1)–Cl(3) 91.78(5)
Cl(3)–Yb(1)–Cl(4) 77.02(4)
Cl(2)–Yb(2)–Cl(4) 79.82(4)
N(1)–Yb(1)–Cl(4)
N(2)–Yb(1)–Cl(2)
89.7(1)
166.4(3)
N(3)–Yb(2)–Cl(4)
N(4)–Yb(2)–Cl(3)
Yb(1)–Cl(3)–Yb(2) 85.19(4)
102.0(1)
179.4(1)
Yb(1)–Cl(2)–Yb(1) 85.75(3)
Yb(1)–Cl(4)–Yb(2) 85.60(4)

Z.-Q. Zhang et al. / Inorganica Chimica Acta 357 (2004) 3173–3180
3177
The six-membered chelating rings formed by metal
atoms and the backbone of the ligands also adopt boat
conformation, with Sm(1) and C(3), Sm(2) and C(24),
Li(1) and C(45) out of the planes N(1)C(2)C(4)N(2)
(plane 1), N(3)C(23)C(25)N(4) (plane 2) and N(5)C(44)-
C(46)N(6) (plane 3), respectively. The dihedral angles
between plane 1 and plane 2, plane 2 and plane 3 are
103.06° and 96.53°, respectively; while the dihedral angle
between plane 1 and plane 3 is 6.86°, which indicates
that the orientation of plane 1 and plane 2, as well as
plane 2 and plane 3 is approximately perpendicular,
while the orientation of plane 1 and plane 3 is nearly
parallel. This disposition can effectively release the steric
congestion among the two b-diketiminate ligands and
the neutral b-diketimine. It is worthy to note that the six
atoms Cl(5), Sm(2), Cl(2), Sm(1), Cl(4) and Li(1) are
nearly coplanar (plane 4) (the mean deviation from the
ꢀ
least-squares plane is 0.007 A). The dihedral angles be-
tween plane 4 and plane 1–3 vary from 88.66° to 91.15°,
which reveals that the orientations of plane 4 and plane
1–3 are also nearly perpendicular.
Fig. 3. Molecular structure of complex 9. Thermal ellipsoids are drawn
at the 20% probability level. Hydrogen atoms are omitted for the sake
of clarity.
Two b-diketiminate ligands are also symmetrically
coordinated to Sm(1) and Sm(2), respectively, and the
ꢀ
averaged Sm–N bond length of 2.374(5) A compares
Table 3
ꢀ
Selected bond lengths (A) and angles (°) in complex 9
4
ꢀ
well with the 2.392(3) A found in L SmCl2(THF)2 [16],
but it is slightly longer than that in L1SmCl2(THF)2
Bond lengths
Sm(1)–N(1)
Sm(1)–N(2)
Sm(1)–Cl(1)
Sm(1)–Cl(2)
Sm(1)–Cl(3)
Sm(1)–Cl(4)
Li(1)–N(5)
N(5)–C(44)
Li(1)–Cl(4)
N(1)–C(2)
2.38(1)
2.38(1)
2.799(3)
2.794(3)
2.803(3)
2.670(3)
2.01(3)
1.28(2)
2.45(2)
1.36(2)
1.38(2)
1.39(2)
1.34(2)
1.28(2)
1.50(2)
Sm(2)–N(3)
Sm(2)–N(4)
Sm(2)–Cl(1)
Sm(2)–Cl(2)
Sm(2)–Cl(3)
Sm(2)–Cl(5)
Li(1)–N(6)
N(6)–C(46)
Li(1)–O(1)
2.380(9)
2.357(9)
2.805(3)
2.789(3)
2.816(3)
2.622(3)
2.08(3)
1.26(2)
1.89(2)
1.33(2)
1.43(2)
1.38(2)
1.36(2)
1.50(2)
1.26(2)
ꢀ
(2.33(1) A) [16]. In contrast to that in complex 7, the
three chlorine bridges in complex 9 are symmetrically
coordinated to the two samarium atoms. The Sm–
Cl(1,2,3) bond lengths range from 2.789(3) to 2.816(3)
ꢀ
ꢀ
A, giving the average bond length of 2.801(3) A, which
is comparable with the corresponding values in com-
plex 7, and L3YbCl(l-Cl)3YbL3(THF) [15], when the
difference in ionic radii is considered. Interestingly, the
N(3)–C(23)
C(23)–C(24)
C(24)–C(25)
N(4)–C(25)
C(45)–C(46)
N(6)–C(46)
ꢀ
C(2)–C(3)
C(3)–C(4)
terminal Sm(1)–Cl(4) bond length is only 0.05 A shorter
than the bridged Sm(2)–Cl(5) bond length; and this
bond length is also apparently longer than those in
complex 7, and L3YbCl(l-Cl)3YbL3(THF) [15], even
the difference in ionic radii is considered. But this
value is still comparable with that in L4SmCl2(THF)2
N(2)–C(4)
N(5)–C(44)
C(44)–C(45)
Bond angles
N(1)–Sm(1)–N(2)
Cl(1)–Sm(1)–Cl(4)
Cl(2)–Sm(1)–Cl(1)
N(2)–Sm(1)–Cl(2)
N(2)–Sm(1)–Cl(4)
N(1)–Sm(1)–Cl(3)
N(5)–Li(1)–N(6)
76.4(3)
91.4(1)
76.72(9)
89.0(3)
103.0(3)
165.8(3)
95.7(11)
N(3)–Sm(2)–N(4)
N(4)–Sm(2)–Cl(2)
Cl(2)–Sm(2)–Cl(1)
Cl(1)–Sm(2)–Cl(5)
N(4)–Sm(2)–Cl(5)
N(3)–Sm(2)–Cl(3)
Sm(1)–Cl(1)–Sm(2)
Sm(1)–Cl(3)–Sm(2)
Cl(4)–Sm(1)–Cl(2)
79.1(4)
93.4(3)
76.71(9)
93.7(1)
96.5(3)
170.1(3)
88.12(9)
87.86(8)
164.7(1)
ꢀ
[16]. The Sm(1)–C(14) distance of 3.19(2) A is compa-
2
ꢀ
rable with that of 3.180(9) A for bridging g -C5H5
bonding in (C5Me5)2Sm(l-C5H5)Sm(C5Me5)2 [26],
which indicates that the complex may be considered to
involve p coordination of the b-diketiminate ligand to
the samarium(1) atom. However, the Sm(2)–C distances
Sm(2)–Cl(2)–Sm(1) 88.54(9)
Cl(2)–Sm(2)–Cl(5)
Sm(1)–Cl(4)–Li(1)
ꢀ
are beyond 3.30 A, which indicates that there is only
pure r bonding between the b-diketiminate ligand and
the samarium(2) atom. The bond lengths of N(5)–C(44)
167.9(1)
136.2(5)
ꢀ
and N(6)–C(46) are 1.28(2) and 1.26(2) A, respectively,
bulkiness of these ligands, one b-diketiminate ligand can
stabilize the lanthanide dichloride, but one edge of the
coordination sphere of the complex formed is much
more open, and the triple chlorine bridge is formed to
meet the coordination saturation when Lewis base is
lacking.
which is consistent with the C@N double bond length;
furthermore, the C(44)–C(45) and C(45)–C(46) bond
lengths compare well with the C–C single bond length.
Thus the neutral b-diketimine adopts the diimine tau-
tomer, which is different from that of the free b-diketi-
mine [27,28].

3178
Z.-Q. Zhang et al. / Inorganica Chimica Acta 357 (2004) 3173–3180
3. Experimental
Nd, 18.51; Found: C, 50.84; H, 5.82; N, 3.63; Nd,
18.36%.
Reactions were performed under pure argon atmo-
sphere with exclusion of air and moisture by Schlenk
techniques. Solvents were dried and freed of oxygen by
refluxing over sodium or sodium benzophenone ketyl
and distilled under argon prior to use. Anhydrous LnCl3
[29] and L2Li [28] were prepared according to the liter-
ature methods. Melting points were determined in sealed
argon-filled capillaries and are uncorrected. Metal
analyses were carried out using complexometric titra-
tion. 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. The IR spectra were re-
corded on a Nicolet-550 FTIR spectrometer as KBr.
3.4. Synthesis of L2YbCl2(THF)2 (4)
Complex 1 (2.93 g, 3.63 mmol) was dissolved in 50 ml
of toluene. The reaction mixture was stirred overnight at
50 °C oil bath. The precipitation was removed by cen-
trifugation. Complex 4 was obtained as red microcrys-
tals from concentrated toluene solution (1.86 g, 74%).
M.p. 172–174 °C (dec). IR (KBr pellet, cmꢀ1): 3418(s),
3144(s), 2967(s), 2923(m), 2847(m), 1597(m), 1559(vs),
1539(vs), 1474(s), 1443(m), 1381(m), 1364(s), 1300(s),
1044(m), 1096(w), 922(w), 764(m). Anal. Calc. for
C29H41Cl2N2O2Yb: C, 50.00; H, 6.37; N, 4.02; Yb,
24.83. Found: C, 49.66; H, 5.91; N, 4.08; Yb, 24.37%.
3.1. Synthesis of L2YbCl(THF)(l-Cl)2Li(THF)2 (1)
3.5. Synthesis of L2SmCl2(THF)2 (5)
A solution of L2Li (25 ml, 5.56 mmol) in THF/hexane
was slowly added to a suspension of YbCl3 (1.55 g, 5.56
mmol) in 40 ml THF at room temperature (r.t.). The
color of the solution gradually changed to red. The re-
action mixture was stirred overnight at r.t., then the
solution was concentrated to 25 ml and cooled at )5 °C.
Complex 1 was obtained as a red microcrystal (3.50 g,
78%). M.p. 169–171 °C (dec.). IR (KBr, cmꢀ1): 3137(s),
2966(s), 2847(s), 2658(w), 1624(m), 1597(m), 1555(s),
1474(s), 1300(s), 1200(m), 1096(w), 1042(w), 768(m),
667(w). Anal. Calc. for C33H49Cl3N2O3LiYb: C, 49.05;
H, 6.11; N, 3.47; Yb, 21.41; Found: C, 48.97; H, 5.98; N,
3.41; Yb, 21.12%.
Complex 5 was prepared similar to that of complex 4,
but complex 2 (2.78 g, 3.54 mmol) was used in place of
complex 1. The orange yellow microcrystals of 5 were
obtained (1.59 g, 67%). M.p. 235–237 °C (dec.) IR (KBr,
cmꢀ1): 3136.5(m), 2962.9(s), 2847.1(m), 1624.2(s),
1597.2(m), 1554.7(s), 1469.9(m), 1442.9(m), 1381.1(m),
1296.3(s), 1199.8(w), 1091.8(w), 1041.6(m), 918.2(w),
763.9(m). Anal. Calc. for C29H41Cl2N2O2Sm: C, 51.92;
H, 6.16; N, 4.18; Sm, 22.41; Found: C, 52.02; H, 6.03; N,
4.23; Sm, 22.29%.
3.6. Synthesis of L2NdCl2(THF)2 (6)
Complex 6 was prepared similar to that of complex 4,
but complex 3 (2.90 g, 3.72 mmol) was used in place of
complex 1. The pale blue crystals were obtained from
concentrated toluene solution (1.76 g, 71%). M.p. 175–
177 °C (dec.) IR (KBr, cmꢀ1): 3137(s), 2967(s), 2847(s),
2658(w), 1597(s), 1555(s), 1443(s), 1381(m), 1300(s),
1200(m), 1096(s), 1042(m), 968(w), 763(m). Anal. Calc.
for C29H41Cl2N2O2Nd: C, 52.40; H, 6.22; N, 4.21; Nd,
21.70; Found: C, 51.98; H, 6.31; N, 3.95; Nd, 21.82%.
3.2. Synthesis of L2SmCl(THF)(l-Cl)2Li(THF)2 (2)
The synthesis of complex 2 was carried out as de-
scribed for 1, but anhydrous SmCl3 (1.59 g, 6.0 mmol)
was used in place of YbCl3. The yellow microcrystals of
2 were obtained from concentrated THF solution at r.t.
(3.56 g, 73%). M.p. 165–167 °C (dec.). IR (KBr, cmꢀ1):
3144(s), 2963(s), 2843(s), 2658(w), 1628(s), 1555(s),
1447(s), 1377(m), 1323(s), 1200(m), 1096(w), 1042(m),
764(m). Anal. Calc. for C33H49Cl3N2O3LiSm: C, 50.47;
H, 6.29; N, 3.57; Sm, 19.14; Found: C, 50.27; H, 6.61; N,
3.87; Sm, 19.03%.
3.7. Synthesis of L2ClYb(l-Cl)3YbL2(THF) (7)
A Schlenk flask was charged with complex 4 (1.26 g,
1.82 mmol) and 50 ml of toluene. The red solution was
warmed to about 70 °C for 10 min, then the supernatant
was removed in vacuum at about 50 °C and the residue
was extracted with toluene. The color of the solution
gradually changed to violet red. The following manip-
ulations were similar to those described above. The vi-
olet red crystals suitable for structural analysis were
obtained from concentrated toluene solution at r.t. (0.58
g, 54%). M.p. 214–216 °C (dec.). IR (KBr, cmꢀ1):
2963(w), 2932(w), 2855(w), 1628(m), 1559(s), 1439(m),
1385(m), 1339(w), 1192(w), 1088(w), 1034(m), 968(w),
3.3. Synthesis of L2NdCl(THF)(l-Cl)2Li(THF)2 (3)
The synthesis of complex 3 was carried out as de-
scribed for 1, but anhydrous NdCl3 (1.33 g, 5.32 mmol)
was used in place of YbCl3. The blue crystals were ob-
tained from concentrated THF solution at r.t. (3.08 g,
71%). M.p. 241–242 °C (dec.). IR (KBr, cmꢀ1): 3171(m),
2963(m), 2843(m), 2658(w), 1624(m), 1555(s), 1474(m),
1296(m), 1381(w), 1188(w), 1034(w), 768(w). Anal. Calc.
for C33H49Cl3N2O3LiNd: C, 50.86; H, 6.34; N, 3.59;

Z.-Q. Zhang et al. / Inorganica Chimica Acta 357 (2004) 3173–3180
3179
768(w). Anal. Calc. for C46H58Cl4N4OYb2: C, 47.19; H,
4.99; N, 4.79; Yb, 29.56; Found: C, 46.73; H, 5.31; N,
4.62; Yb, 29.15%.
3021(s), 2959(s), 2920(s), 2855(s), 1845(s), 1624(s),
1539(s), 1377(s), 1281(s), 1181(s), 1092(m), 1030(m),
984(w), 968(s), 918(w), 810(m), 729(m), 694(m), 598(w),
467(w). Anal. Calc. for C67H84Cl5N6OLiSm2: C, 54.58;
H, 5.74; N, 5.70; Sm, 20.40; Found: C, 54.11; H, 5.90; N,
5.23; Sm, 20.01%.
3.8. Synthesis of L2ClSm(l-Cl)3SmL2(THF) (8)
Compound 8 was prepared similar to complex 7, but
complex 5 (1.02 g, 1.52 mmol) was used in place of
complex 4 and the color of the solution was changed to
orange. The orange red microcrystals were obtained
from concentrated toluene solution at )5 °C (0.44 g,
51%). M.p. 236–238 °C (dec.). IR (KBr, cmꢀ1):
2974.5(m), 2939.7(s), 2878.0(w), 2739.1(s), 2677.4(s),
2492.2(s), 1604.9(m), 1512.3(w), 1473.7(m), 1396.6(m),
1365.7(w), 1169.0(m), 1037.8(m), 752.3(w). Anal. Calc.
for C46H58Cl4N4OSm2: C, 49.09; H, 5.19; N, 4.98; Sm,
26.72; Found: C, 48.70; H, 5.76; N, 4.98; Sm, 26.54%.
3.10. X-ray structure determination
Suitable single crystals of complexes 3, 7 and 9 were
each sealed in a thin-walled glass capillary and intensity
data were collected on a MSC/AFC diffractometer (for
3), Rigaku Mercury CCD (for 7 and 9) equipped with
ꢀ
graphite monochromatized Mo Ka (k ¼ 0:71073 A) ra-
diation. Details of the intensity data collection and
crystal data are given in Table 4. The crystal structures of
these complexes were solved by direct methods and ex-
panded by Fourier techniques. Atomic coordinates and
thermal parameters were refined by full-matrix least-
squares analysis on F 2. All the non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were all gener-
3.9. Synthesis of L2SmCl(l-Cl)3SmL2(l-Cl)Li(L2H)
(THF) (9)
ꢀ
The solvent of the mother liquor of complex 2 was
evaporated to dryness under reduced pressure and the
residue was extracted with toluene. After separation the
precipitation was removed by centrifugation, the toluene
solution was treated as described for 7, and the color of
the solution was changed to orange red. Crystals suit-
able for X-ray structure studies were obtained at )5 °C
(0.08 g). M.p. 215–217 °C (dec.). IR (KBr, cmꢀ1):
ated geometrically (C–H bond lengths fixed at 0.95 A)
with assigned appropriate isotropic thermal parameters.
4. Supplementary data
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Table 4
Crystallographic data for complexes 3 ꢁ 0.5C4H8O, 7 ꢁ 1.5C7H8 and 9 ꢁ 2C7H8
3 ꢁ 0.5C4H8O
C35H53Cl3N2O3:5LiNd
7 ꢁ 1.5C7H8
C56:50H70Cl4N4OYb2
9 ꢁ 2C7H8
C81H100Cl5N6OLiSm2
Formula
Molecular weight
Temperature (K)
Crystal system
815.25
273(2)
1309.09
193(2)
1658.56
193(2)
monoclinic
pale blue, block
C2=c
triclinic
red, chunk
P
monoclinic
yellow, chip
P21=n
Crystal color and habit
Space group
Unit cell dimensions
ꢀ
a (A)
34.570(1)
14.0550(9)
20.999(1)
90
13.2325(1)
14.6918(2)
16.0271(3)
100.57(1)
110.697(7)
96.64(1)
2809.50(7)
2
19.061(2)
26.744(2)
18.506(2)
90
ꢀ
b (A)
ꢀ
c (A)
a (°)
b (°)
c (°)
126.960(5)
90
110.022(4)
90
3
ꢀ
V (A )
8152.8(8)
8
1.328
8863(2)
4
1.243
Z
Dcalc (g cmꢀ3
)
1.547
3.539
1298
l (mmꢀ1
F ð000Þ
)
1.503
3352
1.504
3392
Crystal size (mm)
2hmax (°)
0.22 ꢂ 0.18 ꢂ 0.18
55.0
25 053
0.40 ꢂ 0.30 ꢂ 0.15
55.0
28 353
0.30 ꢂ 0.40 ꢂ 0.21
50.1
81 156
Reflections collected
Independent reflections
Observed reflections
Parameters refined
R
9457
12 676
15 508
5914 (I P 1:5rðIÞ)
388
0.0463
11 410 (I P 2:0rðIÞ)
584
0.0464
14 451 (I P 2:0rðIÞ)
815
0.1265
wR2
0.545
0.1024
0.2124

3180
Z.-Q. Zhang et al. / Inorganica Chimica Acta 357 (2004) 3173–3180
[11] P.G. Hayes, W.E. Piers, R. McDonald, J. Am. Chem. Soc. 124
(2002) 2132.
Data Center, CCDC No. 222574–222576 for complexes
3, 7 and 9, respectively. Copies of this information may
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).
[12] A.G. Avent, A.V. Khvostov, P.B. Hitchcock, M.F. Lappert,
Chem. Commun. (2002) 1410.
[13] P.G. Hayes, W.E. Piers, M. Parvez, J. Am. Chem. Soc. 125 (2003)
5622.
[14] A.G. Avent, P.B. Hitchcock, A.V. Khvostov, M.F. Lappert, A.V.
Protchenko, J. Chem. Soc., Dalton Trans. (2003) 1070.
[15] Y.M. Yao, Y. Zhang, Q. Shen, K.B. Yu, Organometallics 21
(2002) 819.
Acknowledgements
[16] Y.M. Yao, Y.J. Luo, R. Jiao, Q. Shen, K.B. Yu, L.H. Weng,
Polyhedron 22 (2003) 441.
Financial support from the Chinese National Natu-
ral Science Foundation and the Key Laboratory of
Organic Synthesis of Jiangsu Province is gratefully
acknowledged.
[17] Y.M. Yao, M.Q. Xue, Y.J. Luo, Z.Q. Zhang, R. Jiao, Y. Zhang,
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