Synthesis and characterization of β-diketiminate lanthanide complexes: The effect of the bulkiness of ancillary ligand on the reaction

Article abstract of DOI:10.1016/S0022-328X(03)00453-4

The reactions of ytterbium dichlorides with different β-diketiminate ligand ((Ar)NC(Me)CHC(Me)N(Ar′), Ar=Ar′=C₆ H₅ (L¹); Ar=Ar′=2,6-Me₂-C₆H₃ (L²); Ar=C₆H₅, Ar′=2,6-Pr₂ⁱ-C₆H₃ (L³)) with 1 equiv of Cp′Na were studied. It was found that the bulkiness of β-diketiminate ligand and cyclopentadienyl group both have significant effect on the above reaction. For less bulky ligands L¹ and L², the reaction affords not the expected mixed-ligand ytterbium chloride, (C₅H₅)YbLCl or (CH₃C₅H₄)YbCl, but the ligand-redistributed product (C₅H₅)₂YbL or (CH₃C₅H₄)₂YbL. For bulkier ligand L³, the desired anionic ytterbium chloride (C₅H₅)YbL³(μ-Cl)₂ Li(THF)₂ is obtained. For the smallest ligand L¹, the expected ytterbium monochloride can also be obtained using bulky C₅Me₅Na as reactant. Each of these complexes was well characterized, while several have been characterized by X-ray diffraction structure determination.

Full text of DOI:10.1016/S0022-328X(03)00453-4

Journal of Organometallic Chemistry 678 (2003) 108ꢁ116
/
www.elsevier.com/locate/jorganchem
Synthesis and characterization of b-diketiminate lanthanide
complexes: the effect of the bulkiness of ancillary ligand on the
reaction
Yingming Yao a, Mingqiang Xue a, Yunjie Luo a, Zhenqin Zhang a, Rui Jiao a,
Yong Zhang a, Qi Shen a,*, Wingtak Wong b, Kaibei Yu c, Jie Sun d
a Department of Chemistry and Chemical Engineering, Suzhou University, 1 Shizi Street, Suzhou 215006, PR China
b Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China
c Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, PR China
d Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, PR China
Received 28 February 2003; received in revised form 11 May 2003; accepted 14 May 2003
Abstract
The reactions of ytterbium dichlorides with different b-diketiminate ligand ((Ar)NC(Me)CHC(Me)N(Ar?), Arꢀ
/
Ar?ꢀ
/
C6H5 (L1);
ArꢀAr?ꢀ2,6-Me2Ã
/
/
/
C6H3 (L2); ArꢀC6H5, Ar?ꢀ2; 6-Pr2i -C6H3 (L3)) with 1 equiv of Cp?Na were studied. It was found that the
/
bulkiness of b-diketiminate ligand and cyclopentadienyl group both have significant effect on the above reaction. For less bulky
ligands L1 and L2, the reaction affords not the expected mixed-ligand ytterbium chloride, (C5H5)YbLCl or (CH3C5H4)YbCl, but the
ligand-redistributed product (C5H5)2YbL or (CH3C5H4)2YbL. For bulkier ligand L3, the desired anionic ytterbium chloride
(C5H5)YbL3(m-Cl)2Li(THF)2 is obtained. For the smallest ligand L1, the expected ytterbium monochloride can also be obtained
using bulky C5Me5Na as reactant. Each of these complexes was well characterized, while several have been characterized by X-ray
diffraction structure determination.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Organolanthanides; b-Diketiminate ligand; Synthesis; Reactivity; Crystal structures
1. Introduction
their synthesis, and they can coordinate to the metal
center in different bonding models ranging from purely
s to a combination of s and p donation [46]. In
particular, some of these b-diketiminate complexes
have found potential applications as homogeneous
polymerization catalysts. For example, b-diketiminate
zinc complexes can catalyze the alternating copolymer-
ization of CO2 and epoxides [18,22], and stereocontrol
polymerization of lactide [23]; cationic b-diketiminate
scandium methyl complexes have ethylene polymeriza-
tion activities comparable to those of metallocenes [19].
The b-diketiminates have been the subject of intense
interest in recent years [1] and complexes incorporating
main group metals [2ꢁ
39], and lanthanides [40ꢁ
/
17], and transition metals [18ꢁ
/
/45] have been reported. These
ligands have several attractive features. b-Diketiminate
ligands and cyclopentadienyl anions are isoelectronic,
and both of them are monoanions in their deprotonated
forms; the steric and electronic properties of b-diketi-
minate ligands can be readily altered through an
appropriate choice of amine and b-diketone used in
However, the synthesis and reactivity of mixedꢁligand
/
complexes containing b-diketiminate and cyclopentadie-
nyl groups have received scant attention [30,36].
We have recently reported that b-diketiminate ligand
* Corresponding author. Tel.: ꢂ
65112371.
E-mail address: qshen@suda.edu.cn (Q. Shen).
/
86-512-65112513; fax: ꢂ86-512-
/
(DIPPh)2nacnac ((DIPPh)2nacnacꢀ
/
N,N-2,6-diisopro-
pylphenyl-2,4-pentanediimine anion) with two 2,6-dii-
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00453-4

Y. Yao et al. / Journal of Organometallic Chemistry 678 (2003) 108ꢁ
/116
109
sopropylphenyl groups on the nitrogen atoms is a ideal
ligand for the synthesis of mixed-ligand lanthanide
chloride with b-diketiminate and cyclopentadienyl.
These kinds of complexes are important precursors for
the synthesis of the corresponding alkyl, or amido
complexes [40]. Therefore, it is interesting to further
study on the synthesis of these complexes with different
b-diketiminates in understanding the relationship be-
tween the coordination environment of metal center and
their reactivity. It is unexpected that the ligand redis-
tribution occurred when ytterbium dichloride with less
[47]. Complex 2 was also characterized by X-ray
structure analysis (Scheme 1).
The further reaction of above ytterbium dichlorides
with 1 equiv of C5H5Na in THF at room temperature,
after workup, gave orangeꢁ
ingly, the crystals were identified to be (C5H5)2YbL
(Lꢀ
L1, 3; L2, 4), not the desired products
/
red crystals. Quite surpris-
/
(C5H5)YbLCl. It seems that in our present case, the
chloride (C5H5)YbLCl is not stable enough, and will
transform immediately to the most stable one
(C5H5)2YbL (Scheme 2). In comparison with the results
by the similar reaction with [(DIPPh)2nacna-
c]YbCl2(THF)2, in which the mixed ligand ytterbium
chloride can be isolated in high yields [40], it can be
supposed that the bulkiness of b-diketiminate ligand is
the key point for the synthesis of mixed-ligand lantha-
nide chloride with b-diketiminate and cyclopentadienyl.
In order to confirm further, we design a new more
bulky b-diketimine L3H (9) with a phenyl and a 2,6-
diisopropylphenyl on the two N atoms, respectively, and
did the reaction of YbCl3 with freshly prepared L3Li
(from L3H with n-BuLi in toluene), followed with
C5H5Na in THF. After workup, the expected chloride
stabilized by lithium chloride, (C5H5)YbL3(m-
Cl)2Li(THF)2 (5), was really obtained in good yield as
orange microcrystals. In order to elucidate the effect of
the coordinated lithium chloride, we also tried the one
pot reaction of YbCl3 with L2Li and C5H5Na. However,
the product isolated for this reaction is still a ligand-
redistributed product (C5H5)2YbL2 (4) (Section 4.6.2)
(Scheme 3). From these results it might be concluded
that to construct a suitable coordination environment
around the central metal is crucial for stabilizing the b-
diketiminate-cyclopentadienyl ytterbium chloride.
bulky b-diketiminate (here, R?ꢀ
/
Ph or 2,6-Me2Ph)
reacted with 1 equiv of C5H5Na, and the product
(C5H5)2YbL in stead of the desired (C5H5)YbLCl was
obtained. Thus, the effect of the bulkiness of b-
diketiminate and cyclopentadienyl groups on the reac-
tion pathway was studied, respectively. In this paper, we
report these results.
2. Results and discussion
2.1. Synthesis
The metathesis reaction with anhydrous ytterbium
chloride was carried out smoothly with freshly prepared
LLi to give the desired dichlorides LYbCl2(THF)2 (Lꢀ
/
PhNC(Me)CHC(Me)NPh 1), Lꢀ(2,6-
(L1,
/
Me2)PhNC(Me)CHC(Me)NPh(2,6-Me2) (L2, 2) in high
yield even for b-diketiminate (L1), which has no
substituent on the arene rings. Complex 1 was directly
isolated as red precipitate from the reaction solution due
to its sparing solubility in THF. For complex 2, red
microcrystals were obtained after crystallization from
toluene. The IR spectra of these complexes exhibited the
strong absorptions near 1550 and 1530 cmꢃ1, which
We considered that the desired steric congestion
around the lanthanide metal should also be constructed
by change the bulkiness of the other ancillary ligand, i.e.
choosing a suitable substituted cyclopentadienyl as
another ancillary ligand, the ligand redistribution
should also be suppressed. First, we tried the reaction
of complex 2 with 1 equiv of CH3C5H4Na in THF. After
were consistent with partial CÄ/N double bond character
workup,
still
the
unexpected
products,
(CH3C5H4)2YbL2 (6) was isolated. This result indicated
that the CH3C5Hꢃ4 group is still not bulky enough.
Then, we did another reaction with complex 1 (the
smallest b-diketiminate as ancillary ligand) and bulky
Scheme 1.
Scheme 2.

110
Y. Yao et al. / Journal of Organometallic Chemistry 678 (2003) 108ꢁ116
/
C(2)Ã
/
C(3), N(1)Ã
/
C(1) and N(2)Ã/C(3) lie intermediate
between the corresponding single- and double-bond
distances (see Table 1), which suggest significant delo-
calization within the p-system of b-diketiminate back-
bone. The YbÃ
suggesting a negligible p contribution to the b-
diketiminateÃYb bonding in this complex.
/C(1, 2, 3) distances are quite long,
/
2.2.2. (C5H5)2YbL1 (3) and (CH3C5H4)2YbL2 (6)
The molecular structures of complexes 3 and 6 are
shown in Figs. 2 and 3, and their selected bond lengths
and angles are listed in Tables 2 and 3, respectively.
Both complexes 3 and 6 have unsolvated monomeric
structure in the solid state with ytterbium atom bound
to two nitrogen atoms of the b-diketiminate ligand, and
two cyclopentadienyl rings. The geometry about the
ytterbium center is best described as a distorted tetra-
hedron. In complex 6, two methyl groups of the
methylcyclopentadienyl adopt trans conformation.
The b-diketiminate ligand is symmetrically coordi-
nated to the ytterbium atom in 3 and 6. There is the
expected pattern of delocalization within the b-diketi-
minate ligand. The backbone of the ligand (NC3N) and
ytterbium atom form a stable six-membered ring which
adopts a boat conformation. In complex 3, C(8) and Yb
˚
lying 0.14 and 0.90 A out of the NC2N plane,
respectively; in complex 6, C(10) and Yb lying 0.19
˚
and 1.12 A out of the NC2N plane, respectively. The
quite long distances between Yb and the carbon atoms
of the backbone of the b-diketiminate ligand in these
two complexes reveal that the b-diketiminate ligand is
only an N,N?-bonded chelate.
Scheme 3.
C5Me5Na as the reactants. At last, a desired complex
[(C5Me5)YbL1(m-Cl)]2 (7) was really obtained as an only
product (Scheme 4). These results reveal that choice
suitable bulkiness of b-diketiminate and cyclopentadie-
nyl are both important for the synthesis of mixed-ligand
lanthanide chloride supported by b-diketiminate and
cyclopentadienyl.
2.2. Crystal structure determination
2.2.1. L2YbCl2(THF)2 (2)
The molecular structure of complex 2 is shown in Fig.
1, and the selected bond lengths and angles are listed in
Table 1. The ytterbium atom is six-coordinate with two
nitrogen atoms of the b-diketiminate ligand, two
chloride, and two THF molecules in a distorted
octahedron. The molecular structure establishes cis
disposition of the THF molecules, and trans disposition
of the chlorine atoms.
2.2.3. (C5H5)YbL3(m-Cl)2Li(THF)2 (5)
The b-diketiminate ligand is symmetrically coordi-
A drawing of complex 5 is shown in Fig. 4, and
selected bond distances and angles are listed in Table 4.
Complex 5 is a lithium chloride stabilized mixed-ligand
ytterbium chloride. The coordination sphere of the Yb
center is composed of two nitrogen atoms of a b-
diketiminate anion, and the cyclopentadienyl group, and
two chloride to form a distorted pyramidal geometry
with Cl(1), Cl(2), N(1), and N(2) coplanar, and the Cp
centroid vertex, the formal coordination number of the
central metal is seven.
nated to the ytterbium atom with the variation in YbÃ
/
N
˚
˚
bond lengths of 0.004 A (2.300(4) and 2.304(4) A,
respectively), which is similar to that found in
L1GdBr2(THF)2 [45]. Two YbÃ
2.557(1) and 2.538(1) A are apparently shorter than
/
Cl bond lengths of
˚
that in [(DIPPh)2nacnac]YbCl(m-Cl)3Yb[(DIPPh)2nac-
nac](THF) [40]. The bond distances of C(1)Ã
/
C(2),
In complex 5, the b-diketiminate ligand has some h5-
character. The YbÃ
/
C(13, 14, 15), distances are 2.904(4),
˚
2.840(4), and 2.780(4) A, respectively, which are well
C bond distances in the
comparable with the YbÃ
/
indisputably p-arene bonded Yb(h6-C6Me6)(AlCl4)3-
(MeC6H5) [48]. This indicates that the complex involves
p coordination of the b-diketiminate ligand to the
ytterbium atom, which is different from those found in
complexes 2, 3, and 6.
The YbÃ
/
C(ring) distances range from 2.605(4) to
˚
2.616(4) A. The averaged YbÃ
/C(ring) distance of
˚
2.609(5) A is comparable with those in [(C5H5)2YbCl]2
Scheme 4.

Y. Yao et al. / Journal of Organometallic Chemistry 678 (2003) 108ꢁ
/116
111
Fig. 1. Molecular structure of complex 2.
˚
˚
(2.58(6) A) [49], and (C5Me5)2Yb(m-Cl)2Li(Et2O)2
The b-diketiminate ligand is h2-bonded to the ytter-
bium atom in this structure. The YbÃC(1), YbÃC(2),
C(3) distances are quite long, which indicates
that there is only purely s bonding. The b-diketiminate
ligand is also symmetrically coordinated to ytterbium
(2.610(3) A) [50]. The YbÃ
/
Cl bond lengths of 2.629(1),
/
/
˚
and 2.681(1) A in complex 5 are apparently longer than
those in (C5Me5)2Yb(m-Cl)2Li(Et2O)2 [50], which sug-
gests that the steric repulsion play an important role.
and YbÃ
/
atom in complex 7. The averaged YbÃ
/
C(ring) distance is
˚
2.618(7) A, which is comparable with those in complex
2.2.4. [(C5Me5)YbL1(m-Cl)]2 (7)
5, and (C5Me5)2Yb(m-Cl)2Li(Et2O)2 [50]. The averaged
The X-ray structure of complex 7 was also deter-
mined, and the molecular structure is depicted in Fig. 5,
and selected bond lengths and angles are listed in Table
5. Complex 7 has dimeric structure in solid state, which
is different from that of (CH3C5H4)Yb[(DIPPh)2nac-
nac]Cl [40].
˚
Cl bond length of 2.571(3) A in complex 7 is
˚
apparently shorter than that of 2.655(1) A in complex 5.
YbÃ
/
3. Conclusion
Table 1
˚
Selected bond lengths (A) and angles (8) for complex 2
The reaction chemistry of b-diketiminate ytterbium
complexes has been studied. The bulkiness of b-diketi-
Bond lengths
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
/
N(1)
N(2)
Cl(1)
Cl(2)
O(1)
2.300(4)
2.304(4)
2.557(1)
2.538(1)
2.383(4)
YbÃ
N(1)Ã
N(2)Ã
C(1)Ã
C(2)Ã
/
O(2)
2.368(4)
1.337(6)
1.337(6)
1.407(7)
1.388(7)
/
/C(1)
/
/C(3)
/
/
C(2)
C(3)
/
/
Bond angles
N(1)Ã
N(1)Ã
N(2)Ã
O(1)Ã
O(1)Ã
O(2)Ã
O(1)Ã
O(2)Ã
/
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
/
N(2)
Cl(1)
Cl(1)
80.3(1)
93.0(1)
94.1(1)
85.9(1)
178.8(1)
95.0(1)
83.49(9)
85.32(9)
Cl(1)Ã
N(1)ÃYbÃ
N(2)ÃYbÃ
O(1)ÃYbÃ
O(2)ÃYbÃ
O(1)ÃYbÃ
O(2)ÃYbÃ
C(1)ÃC(2)Ã
/
YbÃ
/
Cl(2)
166.57(5)
96.0(1)
97.2(1)
/
/
/
/
Cl(2)
/
/
/
/Cl(2)
/
/
O(2)
N(2)
N(2)
Cl(2)
Cl(2)
/
/
N(1)
N(1)
Cl(1)
Cl(1)
98.7(1)
/
/
/
/
175.3(1)
85.31(9)
86.51(9)
129.3(5)
/
/
/
/
/
/
/
/
/
/
/
/
C(3)
Fig. 2. Molecular structure of complex 3.

112
Y. Yao et al. / Journal of Organometallic Chemistry 678 (2003) 108ꢁ116
/
Table 2
Table 3
˚
˚
Selected bond lengths (A) and angles (8) for complex 3
Selected bond lengths (A) and angles (8) for complex 6
Bond lengths
Bond lengths
YbÃ
YbÃ
YbÃ
YbÃ
/
N(1)
2.307(3) N(1)Ã
/
C(7)
C(9)
1.325(5)
1.329(5)
1.401(5)
1.395(5)
YbÃ
YbÃ
YbÃ
YbÃ
/
N(1)
2.345(4) N(1)Ã
/
C(9)
1.324(6)
1.332(5)
1.402(6)
1.405(6)
/N(2)
2.290(3) N(2)Ã
/
/N(2)
2.301(4) N(2)Ã
/C(11)
/Cent(1)
2.348
2.325
C(7)Ã
/C(8)
/Cent(1)
2.331
2.380
C(9)Ã
/
C(10)
C(11)
/Cent(2)
C(8)Ã/C(9)
/Cent(2)
C(10)Ã
/
Bond angles
N(1)ÃYbÃN(2)
Cent(1)ÃYbÃ
Cent(1)ÃYbÃ
Cent(2)ÃYbÃ
Bond angles
N(1)ÃYbÃN(2)
Cent(1)ÃYbÃ
Cent(1)ÃYbÃ
Cent(2)ÃYbÃ
/
/
80.5(1) C(7)Ã
/
C(8)Ã
Cent(1)ÃYbÃ
Cent(2)ÃYbÃ
/
C(9)
N(1)
N(1)
129.3(4)
110.3
110.6
/
/
83.4(1) C(9)Ã
/
C(10)Ã
Cent(1)ÃYbÃ
Cent(2)ÃYbÃ
/
C(11)
130.9(4)
110.6
107.9
/
/
Cent(2)
128.2
106.6
110.3
/
/
/
/
Cent(2)
N(2)
127.3
105.3
113.6
/
/N(1)
/
/N(2)
/
/
/
/
/
/N(1)
/
/N(2)
/
/
N(2)
Cent(1) is the center of ring C(18)Ã
ring C(23)ÃC(27).
/C(22), Cent(2) is the center of
Cent(1) is the center of ring C(22)Ã
ring C(28)ÃC(32).
/C(26), Cent(2) is the center of
/
/
minate ligand and cyclopentadienyl group has signifi-
cant effect on the reaction pathway of the b-diketimi-
nate ytterbium dichloride. Using less bulky b-
diketiminate as ancillary ligands, the ligand redistribu-
tion occurred, when the ytterbium dichloride reacted
with C5H5Na or CH3C5H4Na in 1:1 molar ratio in
THF. There are two ways to suppress the ligand
redistribution, the bulky b-diketiminate ligand was
used or C5Meꢃ5 was used instead of C5Hꢃ5 or
CH3C5Hꢃ4 : It also was already evident that there was
a diversity of bonding modes possible for the b-
diketiminate ligands in their ytterbium complexes: in
complex 5, the ligand is being h5-bonded to the metal,
whereas in complexes 2, 3, 6, and 7, it is an N,N?-bonded
chelate.
[39] and L2Li [38] were prepared according to the
literature methods.
Melting points were determined in sealed argon filled
capillaries and are uncorrected. Metal analyses were
carried out using complexometric titration. Carbon,
hydrogen and nitrogen analyses were performed by
direct combustion on an EA-1110 instrument, quoted
data are the average of at least two independent
determinations. The IR spectra were recorded on a
Nicolet-550 FTIR spectrometer as KBr pellets. 1H-
NMR spectra were recorded on a Varian-400 spectro-
meter in CDCl3.
4.1. 2-(2,6-Diisopropylphenyl)aminopent-2-en-4-one (8)
A 20.0 cm3 amount of 2,6-diisopropylaniline (0.106
mol) was added to a solution of 2,4-pentanedione (16.4
cm3, 0.159 mol) in toluene (100 cm3) in a round-
bottomed flask. The resulting mixture was heated to
reflux for 8 h, and water was removed as a toluene
azeotrope using a Dean and Stark apparatus. The
reaction mixture was then evaporated to dryness. The
resulting solid was recrystallized from hexane to afford
4. Experimental
Reactions were performed under pure argon with
exclusion of air and moisture by Schlenk techniques.
Solvents were dried and freed of oxygen by refluxing
over Na or sodium benzophenone ketyl and distilled
under argon prior to use. Anhydrous YbCl3 [51], L1Li
2-(2,6-diisopropylphenyl)aminopent-2-en-4-one
(23.9 g, 87%). Anal. Calc. for C17H25NO: C, 78.72; H,
(8)
1
9.71; N, 5.40. Found: C, 78.80; H, 9.78; N, 5.33%. H-
Fig. 4. Molecular structure of complex 5.
Fig. 3. Molecular structure of complex 6.

Y. Yao et al. / Journal of Organometallic Chemistry 678 (2003) 108ꢁ
/116
113
5.22; N, 4.26; Yb, 27.62%. IR (KBr pellet, cmꢃ1
)
3422(m), 2974(s), 2927(m), 2859(m), 1620(s), 1556(vs),
1535(vs), 1489(s), 1439(s), 1373(w), 1364(s), 1300(s),
1038(m), 760(m), 694(s).
4.4. L2YbCl2(THF)2 (2)
A solution of L2Li (35 cm3, 5.47 mmol) in tolueneꢁ
/
hexane was slowly added to a suspension of YbCl3 (1.53
g, 5.47 mmol) in 50 cm3 THF at r.t. The color of the
solution gradually changed to red. The reaction mixture
was stirred overnight at r.t. The solvent was removed in
vacuum and toluene was added to extract the product.
The dissolved portion was removed by centrifugation.
The red micro crystals were obtained from the concen-
trated toluene solution at r.t. (2.96 g, 78%). M.p. 172ꢁ
/
174 8C (dec.). Anal. Calc. for C25H33Cl2N2O2Yb: C,
50.00; H, 6.37; N, 4.02; Yb, 24.83. Found: C, 49.66; H,
Fig. 5. Molecular structure of complex 7.
5.91; N, 4.08; Yb, 24.37%. IR (KBr pellet, cmꢃ1
)
NMR (400 MHz; CDCl3): 1.14 (d, 6H, CH3CHCH3),
1.20 (d, 6H, CH3CHCH3), 1.64 (s, 3H, CH3), 2.13 (s,
3418(m), 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). Crystals suitable for
X-ray crystal structure studies were obtained by recrys-
tallization from toluene at r.t. in a few days.
3H, CH3), 2.99ꢁ/3.06 (m, 2H, CH3CHCH3), 5.21 (s, 1H,
CH ÄC(CH3)N), 7.18 (d, 2H, aromatic protons), 7.28ꢁ
/
/
7.32 (m, 1H, aromatic proton), 12.06 (s, 1H, NH).
4.5. (C5H5)2YbL1 (3)
4.2. 2-(2,6-Diisopropylphenyl)aminopent-2-en-4-
(phenyl)imine L3H (9)
To a THF suspension (30 cm3) of compound 1 (3.29
g, 5.17 mmol) was slowly added a solution of C5H5Na
(5.37 cm3, 5.17 mmol) in THF at r.t. After being stirred
for 24 h, the precipitate was separated by centrifugation
and the solvent was evaporated completely under reduce
pressure. Then ether was added to extract the product
and the dissolved portion was separated by centrifuga-
Aniline hydrochloride (11.0 g, 0.085 mol), compound
8 (22 g, 0.085 mol), and 100 cm3 of absolute EtOH were
added to a 250 cm3 round-bottomed flask. The reaction
mixture was allowed to reflux for 4 h. The reaction
solution was then evaporated to dryness. After stirring
with 40 cm3 saturated sodium carbonate, 2-(2,6-diiso-
propylphenyl)aminopent-2-en-4-(phenyl)imine L3H was
extracted into ethyl ether. Evaporation of solvent and
recrystallization from hexane afforded L3H as a white
crystalline solid (17.0 g, 60%). Anal. Calc. for C23H30N2:
C, 82.59; H, 9.04; N, 8.37. Found: C, 82.52; H, 9.07; N,
8.37%. 1H-NMR (400 MHz; CDCl3): 1.12 (d, 6H,
CH3CHCH3), 1.26 (d, 6H, CH3CHCH3), 1.72 (s, 3H,
tion. The orangeꢁ
concentrated ether solution at ꢃ
g, 38%). M.p. 132ꢁ135 8C (dec.). Anal. Calc. for
/red crystals were obtained from
/
10 8C for 3 days (1.08
/
C27H27N2Yb: C, 58.69; H, 4.92; N, 5.07; Yb, 31.32.
Found: C, 59.01; H, 4.94; N, 5.07; Yb, 31.42%. IR (KBr
pellet, cmꢃ1
) 3445(m), 1632(s), 1597(s), 1559(vs),
1485(s), 1435(m), 1381(s), 1366(s), 1281(s), 1188(m),
1026(m), 748(s), 698(m). The crystals suitable for single
crystal structure studies were obtained by recrystalliza-
CH3), 2.07 (s, 3H, CH3), 2.96ꢁ
/
3.03 (m, 2H,
7.28
CH3CHCH3), 4.88 (s, 1H, CH ÄC(CH3)N), 6.93ꢁ
/
/
(m, 8H, aromatic protons), 12.70 (s, 1H, NH).
4.3. L1YbCl2(THF)2 (1)
tion from ether solution at ꢃ10 8C for a week.
/
4.6. (C5H5)2YbL2 (4)
A solution of L1Li (25 cm3, 4.58 mmol) in tolueneꢁ
/
4.6.1. Method 1
hexane was slowly added to a suspension of YbCl3 (1.28
g, 4.58 mmol) in 40 cm3 THF at room temperature (r.t.).
The color of the solution gradually changed to red. The
reaction mixture was stirred overnight at r.t., then
centrifugation to remove the solution. Complex 1 was
The synthesis of compound 4 was carried out as
described for 3, but L2YbCl2(THF)2 (2) (2.76 g, 3.98
mmol) was used in place of L1YbCl2(THF)2 (1). The
product was collected as orangeꢁ/red microcrystals in
two crops by filtration (0.78 g, 32%). M.p. 186ꢁ
/
188 8C
obtained as a red powder (2.48 g, 85%). M.p. 175ꢁ
178 8C (dec.). Anal. Calc. for C25H33Cl2N2O2Yb: C,
47.10; H, 5.18; N, 4.39; Yb, 27.16. Found: C, 46.43; H,
/
(dec.). Anal. Calc. for C31H35N2Yb: C, 61.16; H, 5.80;
N, 4.60; Yb, 28.43. Found: C, 61.06; H, 5.75; N, 4.60;
Yb, 28.24%. IR (KBr pellet, cmꢃ1) 3449(m), 2920(w),

114
Y. Yao et al. / Journal of Organometallic Chemistry 678 (2003) 108ꢁ116
/
Table 4
Table 5
˚
˚
Selected bond lengths (A) and angles (8) for complex 5
Selected bond lengths (A) and angles (8) for complex 7
Bond lengths
Bond lengths
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
/
N(1)
2.330(2) YbÃ
2.275(2) YbÃ
2.630(1) YbÃ
2.680(1) YbÃ
2.613(3) YbÃ
2.605(3) N(1)Ã
2.610(3) N(2)Ã
/
Cent(1)
C(14)
C(15)
2.320
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
YbÃ
/
N(1)
2.340(5)
2.328(5)
2.563(3)
2.580(3)
2.609(7)
2.634(7)
2.639(7)
2.617(6)
YbÃ
YbÃ
YbÃ
YbÃ
N(1)Ã
N(2)Ã
C(1)Ã
C(2)Ã
/
C(22)
C(av)
C(1)
2.594(7)
2.618(7)
3.210(7)
3.179(7)
1.329(8)
1.338(9)
1.38(1)
/N(2)
/
2.906(3)
2.840(3)
2.781(3)
1.679
/N(2)
/
/
Cl(1)
Cl(2)
C(24)
C(25)
C(26)
C(27)
C(28)
C(av)
/
/
Cl(1)
Cl(1A)
C(18)
C(19)
C(20)
C(21)
/
/
/
C(16)
/
/C(3)
/
/
Cent(2)
/
/C(1)
/
/C(14)
1.317(4)
1.343(4)
1.432(4)
1.403(4)
/
/C(3)
/
/C(16)
/
/
C(2)
C(3)
/
2.606(3) C(14)Ã
2.611(3) C(15)Ã
2.609(3)
/
C(15)
C(16)
/
/
1.39(1)
/
/
Bond angles
N(1)ÃYbÃN(2)
Cl(1)ÃYbÃCl(2)
N(1)ÃYbÃ
N(2)ÃYbÃ
/
/
/
78.4(2)
83.0(1)
139.0(2)
84.2(2)
N(1)Ã
N(2)Ã
C(1)Ã
/
YbÃ
/
Cl(2)
84.3(2)
135.9(2)
129.1(7)
Bond angles
N(1)ÃYb(1)Ã
Cl(1)ÃYb(1)Ã
Cl(1)ÃYb(1)Ã
Yb(1)ÃCl(1)Ã
Cent(1)Ã
/
/
/
YbÃ
/Cl(2)
/
/
N(2)
78.34(8) N(1)Ã
82.38(3) N(2)Ã
136.49(6) N(1)Ã
90.1(2) Yb(1)Ã
97.57
/
Yb(1)Ã
Yb(1)Ã
Yb(1)Ã
Cl(2)Ã
/
Cl(1)
89.56(6)
82.91(6)
/
/Cl(1)
/
C(2)ÃC(3)
/
/
/
Cl(2)
N(2)
Li(1)
/
/
Cl(2)
/
/Cl(1)
/
/
/
/
Cl(2) 142.90(6)
Li(1) 89.1(2)
/
/
/
/
/
Yb(1)Ã
/Cent(2)
4.8. (CH3C5H4)2YbL2 (6)
Cent(1) is the center of ring C(24)Ã
ring N1, C(14)ÃC(16), N(2).
/C(28), Cent(2) is the center of
/
The synthesis of complex 6 was carried out as
described for 4, but (CH3C5H4)Na (7.2 cm3, 3.56
mmol) was used instead of C5H5Na. The product was
1624(s), 1555(vs), 1466(s), 1435(s), 1377(m), 1281(s),
1181(s), 1096(m), 1026(m), 768(s).
collected as orangeꢁ
M.p. 186ꢁ188 8C (dec.). Anal. Calc. for C33H36N2Yb:
C, 62.55; H, 5.73; N, 4.42; Yb, 27.30. Found: C, 62.31;
H, 5.61; N, 4.35; Yb, 27.53%. IR (KBr pellet, cmꢃ1
/red microcrystals (0.68 g, 30%).
/
)
3445(s), 2961(m), 1627(s), 1559(vs), 1496(m), 1438(m),
1382(m), 1290(s), 1176(m), 1039(m), 756(m). The crys-
tals suitable for single crystal structure studies were
obtained by recrystallization from toluene solution at
r.t. for a few days.
4.6.2. Method 2
To a slurry of anhydrous YbCl3 (1.75 g, 6.26 mmol) in
about 40 cm3 THF was slowly added the solution of
L2Li (20 cm3, 6.26 mmol) in tolueneꢁ
hexane at r.t. After
/
YbCl3 disappeared completely, the THF solution of
C5H5Na (9.8 cm3, 6.26 mmol) was added slowly. The
mixture was stirred at r.t. for another 48 h, and then the
precipitate was removed from the reaction mixture by
centrifugation. THF was completely removed in vacuum
and ether was added to extract the product. The
precipitation was removed again by centrifugation.
4.9. [(C5Me5)YbL1(m-Cl)]2 (7)
To a THF solution (20 cm3) of compound 1 (1.51 g,
2.37 mmol) was slowly added a solution of C5Me5Na
(3.6 cm3, 2.37 mmol) in THF at r.t. After being stirred at
30 8C for 48 h, the precipitate was separated by
centrifugation and the solvent was evaporated comple-
tely under reduce pressure. Then toluene was added to
extract the product and the dissolved portion was
separated by centrifugation. The red crystals suitable
for single crystal structure studies were obtained from
concentrated toluene solution at r.t. for a few weeks
The orangeꢁ/red microcrystals were obtained from the
concentrated ether solution at ꢃ
/
10 8C (1.26 g, 33%).
4.7. (C5H5)YbL3(m-Cl)2Li(THF)2 (5)
The synthesis of compound 5 was carried out as
described for 4 (Section 4.6.2), but L3Li (3.76 mmol) was
used in place of L2Li. The product was collected as
orange microcrystals in two crops by filtration (2.0 g,
(0.74 g, 53%). M.p. 152ꢁ155 8C (dec.). Anal. Calc. for
/
C27H32ClN2Yb: C, 54.68; H, 5.44; N, 4.72; Yb, 29.17.
Found: C, 54.32; H, 5.53; N, 4.58; Yb, 28.75%. IR (KBr
pellet, cmꢃ1) 3440(s), 1624(s), 1566(s), 1481(s), 1432(s),
1312(s), 1107(m), 1026(m), 751(s), 682(m).
67%). M.p. 186ꢁ188 8C (dec.). Anal. Calc. for
/
C36H50Cl2LiN2O2Yb: C, 54.48; H, 6.35; N, 3.53; Yb,
21.80. Found: C, 54.23; H, 6.36; N, 3.49; Yb, 21.98%. IR
(KBr pellet, cmꢃ1) 3441(s), 2963(m), 1628(s), 1559(vs),
1493(m), 1439(m), 1385(m), 1292(s), 1177(m), 1038(m),
752(m). The crystals suitable for single crystal structure
studies were obtained by recrystallization from ether
4.10. Crystal structure determination
Suitable single crystals of complexes 2, 3, 5, 6 and 7
were sealed in thin-walled glass capillary for single-
crystal structure determination. Intensity data were
collected at ambient temperature on a MSC/AFC
solution at ꢃ10 8C for a few days.
/

Y. Yao et al. / Journal of Organometallic Chemistry 678 (2003) 108ꢁ
/116
115
Table 6
Crystallographic data for complexes 2, 3, 5, 6 and 7
Compound
2
3
5
6
7
Empirical formula
M
C29H41Cl2N2O2Yb
693.60
298(1)
C27H27N2Yb
552.55
290(2)
C36H50Cl2LiN2O2Yb
793.69
193(1)
C33H36N2Yb
633.68
293(2)
C27H32ClN2Yb
593.04
293(2)
Temperature (K)
˚
Radiation (A)
0.71069
Orthorhombic
Pbca
0.71073
Monoclinic
P2(1)/n
0.71070
Triclinic
¯
P1
0.71073
Monoclinic
P2(1)/n
0.71073
Triclinic
¯
P1
Crystal system
Space group
Unit cell dimensions
/
/
˚
a (A)
19.040(1)
15.104(2)
21.130(2)
90
9.428(2)
17.317(5)
14.469(4)
90
11.436(2)
12.036(2)
14.905(3)
94.049(2)
106.357(3)
109.577(2)
1823.6(5)
2
14.717(2)
10.299(2)
19.118(3)
90
9.9668(6)
11.9749(7)
12.4949(7)
109.758(1)
104.928(1)
107.024(1)
1232.1(1)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
90
90
95.17(2)
90
99.26(1)
90
3
˚
V (A )
6076.6(8)
8
1.516
2353(1)
4
1.560
2860.0(8)
4
1.472
Z
rcalc (g cmꢃ3
)
1.445
27.42
1.598
39.20
m (Moꢁ
F(000)
Reflections collected
/
Ka) (cmꢃ1
)
32.80
2792
39.90
1092
32.93
1272
806
19 177
590
7499
37 000
7574 (0.033)
0.97
5016
4377 (0.0214)
0.917
5756
5032 (0.0185)
0.925
Unique reflections (Rint
Goodness-of-fit
)
8013 (0.023)
0.988
0.027
5449 (0.0783)
1.043
0.0482
R
0.033
0.035
0.0247
0.0524
0.0281
0.0608
WR
0.036
0.1202
diffractometer (for 2), Siemens P4 diffractometer (for 3
and 6), Rigaku Mercury CCD (for 5), and Bruker
SMART CCD area detector (for 7) equipped with
Acknowledgements
Financial support from the Chinese National Natural
Science Foundation, and the Department of Education
of Jiangsu Province is gratefully acknowledged.
graphite monochromatized MoꢁKa radiation. Crystal
/
data, data collection and refinement parameters are
summarized in Table 6.
The crystal structures of these complexes were solved
by direct methods and expanded by Fourier techniques.
Atomic coordinates and thermal parameters were re-
fined by full-matrix least-squares analysis on F2. All the
non-hydrogen atoms were refined anisotropically. Hy-
References
[1] L. Bourget-Merle, M.F. Lappert, J.R. Severn, Chem. Rev. 102
(2002) 3031.
[2] J.D. Farwell, P.B. Hitchcock, M.F. Lappert, J. Chem. Soc. Chem.
Commun. (2002) 456.
drogen atoms were all generated geometrically (CÃ
/
H
˚
[3] S. Harder, Organometallics 21 (2002) 3782.
[4] A.P. Dove, V.C. Gibson, E.L. Marshall, A.J.P. White, D.J.
Williams, J. Chem. Soc. Chem. Commun. (2002) 1208.
[5] Y. Ding, Q. Ma, H.W. Roesky, R. Herbst-Irmer, I. Uson, M.
Noltemeyer, H.-G. Schmidt, Organometallics 21 (2002) 5216.
[6] Y. Ding, H.W. Roesky, M. Noltemeyer, H.-G. Schmidt, P.P.
Power, Organometallics 20 (2001) 1190.
bond lengths fixed at 0.95 A), with assigned appropriate
isotropic thermal parameters.
5. Supplementary data
[7] M. Stender, A.D. Phillips, P.P. Power, Inorg. Chem. 40 (2001)
5314.
[8] P.J. Bailey, R.A. Coxall, C.M. Dick, S. Fabre, S. Parsons,
Organometallics 20 (2001) 798.
[9] A.E. Ayers, T.M. Klapotke, H.V.R. Dias, Inorg. Chem. 40 (2001)
¨
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Center CCDC nos. 200112-174632 for complexes
2, 3, 5, 6, 7. Copies of this information may be obtained
free of charge from The Director, CCDC, 12 Union
1000.
[10] A.P. Dove, V.C. Gibson, E.L. Marshall, A.J.P. White, D.J.
Williams, J. Chem. Soc. Chem. Commun. (2001) 283.
[11] A. Akkari, J.J. Byrne, I. Saur, G. Rima, H. Gornitzka, J. Barrau,
J. Organomet. Chem. 622 (2001) 190.
Road, Cambridge CB2 1EZ, UK (Fax: ꢂ44-1223-
/
336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
[12] V.C. Gibson, J.A. Segal, A.J.P. White, D.J. Williams, J. Am.
Chem. Soc. 122 (2000) 7120.

116
Y. Yao et al. / Journal of Organometallic Chemistry 678 (2003) 108ꢁ116
/
[13] C.E. Radzewich, I.A. Guzei, R.F. Jordan, J. Am. Chem. Soc. 121
(1999) 8673.
[32] L.W.M. Lee, W.E. Piers, M.J. Elsegood, W. Clegg, M. Parvez,
Organometallics 18 (1999) 2947.
[14] F. Cosledan, P.B. Hitchcock, M.F. Lappert, J. Chem. Soc. Chem.
Commun. (1999) 705.
[33] B. Qian, W.J. Scanlon, IV, M.R. Smith, III, D.H. Motry,
Organometallics 18 (1999) 1693.
[15] C.E. Radzewich, M.P. Coles, R.F. Jordan, J. Am. Chem. Soc. 120
(1998) 9384.
[34] M. Cheng, E.B. Lobkovsky, G.W. Coates, J. Am. Chem. Soc. 120
(1998) 11018.
[16] B. Qian, D.L. Ward, M.R. Smith, III, Organometallics 17 (1998)
3070.
[35] W.K. Kim, M.J. Fevola, L.M. Liable-Sands, A.L. Rheingold,
K.H. Theopold, Organometallics 17 (1998) 4541.
[36] M. Rahim, N.J. Taylor, S. Xin, S. Collins, Organometallics 17
(1998) 1315.
[17] W. Clegg, E.K. Cope, A.J. Edwards, F.S. Mair, Inorg. Chem. 37
(1998) 2317.
[18] S.D. Allen, D.R. Moore, E.B. Lobkovsky, G.W. Coates, J. Am.
Chem. Soc. 124 (2002) 14284.
[37] V.C. Gibson, P.J. Maddox, C. Newton, C. Redshaw, G.A. Solan,
A.J.P. White, D.J. Williams, J. Chem. Soc. Chem. Commun.
(1998) 1651.
[19] P.G. Hayes, W.E. Piers, R. McDonald, J. Am. Chem. Soc. 124
(2002) 2132.
[38] P.H.M. Budzelaar, R. Gelder, A.W. Gal, Organometallics 17
(1998) 4121.
[20] L.A. MacAdams, W.-K. Kim, L.M. Liable-Sands, I.A. Guzei,
A.L. Rheingold, K.H. Theopold, Organometallics 21 (2002) 952.
[21] D.J.E. Spencer, A.M. Reynolds, P.L. Holland, B.A. Jazdzewski,
C. Duboc-Toia, L.L. Pape, S. Yokota, Y. Tachi, S. Itoh, W.B.
Tolman, Inorg. Chem. 41 (2002) 6307.
[39] J. Feldman, S.J. McLain, A. Parthasarathy, W.J. Marshall, J.C.
Clabrese, S.D. Arthur, Organometallics 16 (1997) 1514.
[40] Y.M. Yao, Y. Zhang, Q. Shen, K.B. Yu, Organometallics 21
(2002) 819.
[22] M. Cheng, D.R. Moore, J.J. Reczek, B.M. Chamberlain, E.B.
Lobkovsky, G.W. Coates, J. Am. Chem. Soc. 123 (2001) 8738.
[23] B.M. Chamberlain, M. Cheng, D.R. Moore, T.M. Ovitt, E.B.
Lobkovsky, G.W. Coates, J. Am. Chem. Soc. 123 (2001) 3229.
[24] J. Prust, A. Stasch, W. Zheng, H.W. Roesky, E. Alexopoulos, I.
[41] A.G. Avent, A.V. Khvostov, P.B. Hitchcock, M.F. Lappert, J.
Chem. Soc. Chem. Commun. (2002) 1410.
[42] D. Neculai, H.B. Roesky, A.M. Neculai, J. Magull, H.-G.
Schmidt, M. Noltemeyer, J. Organomet. Chem. 643 (2002) 47.
[43] P.B. Hitchcock, M.F. Lappert, S. Tian, J. Chem. Soc. Dalton
Trans. (1997) 1945.
Uso´n, D. Bohler, T. Schuchardt, Organometallics 20 (2001) 3825.
¨
[25] P.G. Hayes, W.E. Piers, L.W.M. Lee, L.K. Knight, M. Parvez,
M.R.J. Elsegood, W. Clegg, Organometallics 20 (2001) 2533.
[26] X. Dai, T.H. Warren, J. Chem. Soc. Chem. Commun. (2001)
1998.
[44] D. Drees, J. Magull, Z. Anorg. Allg. Chem. 621 (1995) 948.
[45] D. Drees, J. Magull, Z. Anorg. Allg. Chem. 620 (1994) 814.
[46] J.E. Parks, R.H. Holm, Inorg. Chem. 7 (1968) 1408.
[47] D.S. Richeson, J.F. Mitchell, K.H. Theopold, J. Am. Chem. Soc.
109 (1987) 5868.
[27] B.A. Jazdzewski, P.L. Holland, M. Pink, V.G. Young, Jr., D.J.E.
Spencer, W.B. Tolman, Inorg. Chem. 40 (2001) 6097.
[28] S. Yokota, Y. Tachi, N. Nishiwaki, M. Ariga, S. Itoh, Inorg.
Chem. 40 (2001) 5316.
[48] H.Z. Liang, Q. Shen, J.W. Guan, Y.H. Lin, J. Organomet. Chem.
474 (1994) 113.
[49] T. Akhnoukh, J. Muller, K. Qiao, X.F. Li, R.D. Fischer, J.
¨
[29] V.C. Gibson, C. Newton, C. Redshaw, G.A. Solan, A.J.P. White,
D.J. Williams, Eur. J. Inorg. Chem. (2001) 1895.
[30] R. Vollmerhaus, M. Rahim, R. Tomaszewski, S. Xin, N.J. Taylor,
S. Collins, Organometallics 19 (2000) 2161.
Organomet. Chem. 408 (1991) 47.
[50] P.L. Watson, J.F. Whitney, R.L. Harlow, Inorg. Chem. 20 (1981)
3271.
[51] M.D. Taylor, C.P. Carter, J. Inorg. Nucl. Chem. 24 (1962)
387.
[31] M. Cheng, A.B. Attygalle, E.B. Lobkovsky, G.W. Coates, J. Am.
Chem. Soc. 121 (1999) 11583.