Rare earth metal complexes based on β-diketiminato and novel linked bis(β-diketiminato) ligands: Synthesis, structural characterization and catalytic application in epoxide/CO2-copolymerization

Article abstract of DOI:10.1016/j.jorganchem.2005.03.066

Mesityl substituted β-diketiminato lanthanum and yttrium complexes [(BDI)Ln{N(SiRMe₂)}₂] (BDI = ArNC(Me)CHC(Me)NAr, Ar = 2,4,6-Me₃C₆H₂, Ln = La, R = Me (1), H (2a); Ln = Y, R = H (2b)) can be prepared

Full text of DOI:10.1016/j.jorganchem.2005.03.066

Journal of Organometallic Chemistry 690 (2005) 5182–5197
www.elsevier.com/locate/jorganchem
Rare earth metal complexes based on b-diketiminato and novel linked
bis(b-diketiminato) ligands: Synthesis, structural characterization
and catalytic application in epoxide/CO2-copolymerization
*
Daniela V. Vitanova, Frank Hampel, Kai C. Hultzsch
Institut fu¨r Organische Chemie, Friedrich-Alexander Universita¨t Erlangen-Nu¨rnberg, Henkestr. 42, D-91054 Erlangen, Germany
Received 5 February 2005; received in revised form 29 March 2005; accepted 29 March 2005
Available online 15 June 2005
Abstract
Mesityl substituted b-diketiminato lanthanum and yttrium complexes [(BDI)Ln{N(SiRMe2)}2] (BDI = ArNC(Me)CHC(Me)-
NAr, Ar = 2,4,6-Me3C6H2, Ln = La, R = Me (1), H (2a); Ln = Y, R = H (2b)) can be prepared via facile amine elimination starting
from [La{N(SiMe3)2}3] and [Ln{N(SiHMe2)2}3(THF)2] (Ln = Y, La), respectively. The X-ray crystal structure analysis of 1 revealed
a distorted tetrahedral geometry around lanthanum with a g2-bound b-diketiminato ligand. A series of novel ethylene- and cyclo-
hexyl-linked bis(b-diketiminato) ligands [C2H4(BDIAr)2]H2 and [Cy(BDIAr)2]H2 [Ar = Mes (=2,4,6-Me3C6H2), DEP (=2,6-
Et2C6H3), DIPP (=2,6-i-Pr2C6H3)] were synthesized in a two step condensation procedure. The corresponding bis(b-diketiminato)
yttrium and lanthanum complexes were obtained via amine elimination. The X-ray crystal structure analysis of the ethylene-bridged
bis(b-diketiminato) complex [{C2H4(BDIMes)2}YN(SiMe3)2] (3b) and cyclohexyl-bridged complexes [{Cy(BDIMes)2}LaN(SiHMe2)2]
(7) and [{Cy(BDIDEP)2}LaN(SiMe3)2] (8) revealed a distorted square pyramidal coordination geometry around the rare earth metal,
in which the amido ligand occupies the apical position and the two linked b-diketiminato moieties form the basis. The geometry of
the bis(b-diketiminato) ligands depends significantly on the linker unit. While complexes with an ethylene-linked ligand adopt a
cisoid arrangement of the two aromatic substituents, complexes with cyclohexyl linker adopt a transoid arrangement. Either one
(3b) or both (7, 8) of the b-diketiminato moieties are tilted out of the g2 coordination mode, resulting in close Lnꢀ ꢀ ꢀC contacts.
The b-diketiminato and linked bis(b-diketiminato) complexes were moderately active in the copolymerization of cyclohexene oxide
with CO2. A maximum of 92% carbonate linkages were obtained using the ethylene-bridged bis(b-diketiminato) complex
[{C2H4(BDIMes)2}LaN(SiHMe2)2] (4).
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Non-metallocene complexes; Rare earth metals; b-Diketiminato complexes; Epoxide/CO2-copolymerization
1. Introduction
development of non-metallocene catalyst systems [3].
Non-cyclopentadienyl ligands can be easily modified in
their electronic and steric properties, allowing facile cat-
alyst tuning.
The utilization of CO2 as a C1 feedstock is an appeal-
ing goal in contemporary catalysis research, because CO2
is naturally abundant, inexpensive, nontoxic and non-
flammable [4]. In particular, the metal-catalyzed copoly-
merization of CO2 and epoxides has been studied
extensively, because the resulting polycarbonates are bio-
degradable polymers with attractive material properties
The organometallic chemistry of the rare earth ele-
ments has attracted significant attention in particular
due to their high catalytic activity for a wide range of or-
ganic transformations [1] and polymerizations [2]. An
increasingly important field of research focuses on the
*
Corresponding author. Fax: +49 9131 8526865.
E-mail address: hultzsch@chemie.uni-erlangen.de (K.C. Hultzsch).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.03.066

D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
5183
[5]. Homogeneous catalyst systems based on b-diketimi-
2. Results and discussion
nato zinc [5d,6] and salen chromium [5b,7] complexes are
most prominent examples of recent developments.
Despite their wide application in polymerization
catalysis, there has been no example of a well-defined
homogeneous rare earth metal based catalyst system
for the epoxide/CO2 copolymerization. Only some ill-
defined ternary catalyst systems, consisting of a rare
earth metal carboxylate, a zinc or aluminum alkyl
and glycerol, have been reported [8]. The role of the
rare earth metal in these systems is not clear at present,
because most of these systems are also active in the ab-
sence of the rare earth metal. Furthermore, it was re-
ported that ytterbium naphthalide, an insoluble
compound, produces a small amount of polycarbonate
besides the cyclic carbonate main product [9]. Interest-
ingly, rare metal complexes are well known to activate
epoxides [10] and CO2 [11,12], therefore the lack of a
well-defined homogeneous rare earth metal based epox-
ide/CO2 copolymerization catalyst system seemed
rather astonishing to us.
We came to the conclusion that the most promising
candidates for homogeneous rare earth metal based
epoxide/CO2 copolymerization catalyst systems would
utilize b-diketiminato ligands [13], in analogy to highly
active b-diketiminato zinc complexes. b-Diketiminato
rare earth metal complexes have been prepared via salt
metathesis [14]. However, for practical synthetic reasons
we decided to utilize the more convenient single-step
amine elimination route [15].
2.1. Synthesis of b-diketiminato complexes
The mesityl substituted b-diketiminato ligand
(BDI)H reacted selectively with [La{N(SiMe3)2}3] [18]
at 115 ꢁC within 18 h to yield the mono b-diketiminato
complex 1 in 98% yield (Scheme 1). Reactions with the
sterically less hindered and more reactive [Ln{N(SiH-
Me2)2}3(THF)2] (Ln = Y, La) [19] could be performed
under significant milder conditions (25 ꢁC for La, 40
ꢁC for Y). The bis(dimethylsilyl)amido complexes 2a
and 2b were obtained free of coordinated THF.
Attempts to synthesize analogous 2,6-diisopropylphe-
nyl substituted b-diketiminato complexes were plagued
by very slow reactions at high temperatures (65–95 ꢁC)
and incomplete conversion, even when the more reactive
trisamido complexes [Ln{Ni-Pr2}3(THF)2] (Ln = Y, La)
[20] were employed. Furthermore, in the reaction of
[La{Ni-Pr2}3(THF)2] with either b-diketiminato ligand
an inseparable mixture of products was formed, most
likely mono and bis(b-diketiminato) complexes. The yt-
trium aryl complex [Y(o-C6H4CH2NMe2)3] was also
unsuccessfully applied in complex synthesis, no b-dike-
timinato complexes were formed and only decomposi-
tion of the yttrium aryl starting material was observed.
The 1H and 13C NMR spectra of complexes 1, 2a and
2b are in agreement with a C2v symmetric structure, giv-
ing rise to a single signal for the SiCH3 groups and one
signal for the ortho methyl groups on the mesityl
substituents.
In this paper, we report the synthesis and structural
characterization of b-diketiminato and novel linked
bis(b-diketiminato) rare earth metal complexes [16,17]
as well as their application in the copolymerization of
CO2 and cyclohexene oxide.
The high solubility of complexes 1, 2a and 2b in aro-
matic and aliphatic solvents suggested a monomeric
structure, which was confirmed for complex 1 via X-
ray diffraction analysis. Suitable pale yellow crystals of
N(SiMe3)2
N(SiMe3)2
[La{N(SiMe3)2}3]
N
N
La
toluene,
115˚C, 18 h
1
N
N
H
(BDI)H
[Ln{N(SiHMe2)2}3(THF)2]
N(SiHMe2)2
N(SiHMe2)2
N
Ln
hexanes,
25 - 40˚C, 24 h
N
2a Ln = La
2b Ln = Y
Scheme 1.

5184
D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
˚
0.88 A for molecule b). The b-diketiminato ligand is
essentially planar, with the largest deviation being C2
˚
for molecule a (0.059 A), respectively C1Õ for molecule
˚
b (0.078 A). The La–N bond lengths for the b-diketim-
˚
inato ligand (2.511(4) and 2.521(4) A for molecule a,
˚
2.538(4) and 2.493(4) A for molecule b) are at the upper
˚
limit of typical La–N bonds (2.30–2.49 A [21]), but com-
parable to other b-diketiminato rare earth metal com-
plexes [14], when considering the larger ionic radius of
lanthanum. The La–N bonds to the bis(trimethyl-
silyl)amido ligands on the other hand are significant
˚
shorter (2.387(4)–2.415(4) A), well within the typical
range of La–N bonds. The aromatic substituents are ori-
ented perpendicular to the plane of the b-diketiminato
moiety, with a slight tilt towards the exo-amido ligand
[14g]. The amido ligands show only weak monoagostic
interactions [19,21,22]. One of the two silicon atoms
on each amido ligand gets slightly closer to lanthanum
Fig. 1. ORTEP diagram of the molecular structure of one of the two
independent molecules of 1. Thermal ellipsoids are drawn at the 50%
probability level. Hydrogen atoms have been omitted for the sake of
clarity.
˚
(Laꢀ ꢀ ꢀSi = 3.4948(18) vs. 3.655(2) A and 3.448(2) vs.
˚
3.611(2) A for molecule a; 3.3842(16) vs. 3.677(2) A
˚
1 were obtained by cooling of a concentrated pentane
solution to ꢁ20 ꢁC. An ORTEP diagram of one of the
two independent molecules of compound 1 is shown in
Fig. 1, crystallographic data are compiled in Table 4,
selected bond lengths and angles are summarized in
Table 1.
˚
and 3.5259(18) vs. 3.565(2) A for molecule b), concom-
itant with a decrease in the La–N–Si angle (114.7(2)ꢁ vs.
124.2(2)ꢁ and 113.0(2)ꢁ vs. 123.2(2)ꢁ for molecule a;
110.1(2)ꢁ vs. 126.8(2)ꢁ and 116.7(2)ꢁ vs. 119.2(2)ꢁ for
molecule b), while the Si–N–Si angle remains normal
(close to 120ꢁ). Finally, in molecule b one of the SiMe3
methyl groups is in close contact with lanthanum
The lanthanum atom is coordinated in a distorted tet-
rahedral fashion by the b-diketiminato and two amido
ligands. The b-diketiminato ligand is coordinated in a
g2-fashion, as indicated by long lanthanum–carbon dis-
˚
(3.117(6) A).
2.2. Synthesis of linked bis(b-diketiminato) lanthanum
and yttrium complexes
˚
tances (3.48–3.86 A for both independent molecules).
The lanthanum atom is situated slightly out of the plane
˚
of the b-diketiminato ligand (0.758 A for molecule a,
2.2.1. Synthesis of linked bis(b-diketiminato)ligands
The linked bis(b-diketiminato) ligands were pre-
pared through a two-step standard condensation route
(Scheme 2). Reaction of 2,4-pentadione and an aniline
derivative yields a b-enaminoketone. The carbonyl func-
tion of this intermediate was activated using MeerweinÕs
salt, [Et3O]+[BF4]ꢁ, in order to introduce the ethylene
diamine or trans-cyclohexane-1,2-diamine linkers. Over-
all the ligand synthesis is highly modular and allows
easy modification of either the linker unit or the aro-
matic substituents.
Table 1
˚
˚
Selected bond lengths (A), atomic distances (A) and angles (ꢁ) for 1
1
Molecule a
Molecule b
La–N1
La–N2
2.511(4)
2.521(4)
2.415(4)
2.387(4)
3.4948(18)
3.448(2)
–
2.538(4)
2.493(4)
2.388(4)
2.401(4)
3.3842(16)
3.5259(18)
3.117(6)
La–N3
La–N4
Laꢀ ꢀ ꢀSi2
Laꢀ ꢀ ꢀSi3
Laꢀ ꢀ ꢀC43
2.2.2. Complex synthesis and structural characterization
Reaction of the mesityl substituted linked bis-
(b-diketiminato) ligand [C2H4(BDIMes)2]H2 with [Ln-
{N(SiMe3)2}3] (Ln = La, Y) proceeded at 60–70 ꢁC in
hexanes or toluene, under significantly milder conditions
than for the mono(b-diketiminato) ligand (BDI)H; gen-
erating the desired linked bis(b-diketiminato) complexes
3a and 3b in high yield (Scheme 3). The more reactive
[La{N(SiHMe2)2}3(THF)2] formed the THF-free
bis(dimethylsilyl)amido complex 4 at room temperature.
The increased steric hindrance of the aromatic substitu-
ents in [C2H4(BDIDIPP)2]H2 required higher reaction
N1–La–N2
N1–La–N3
72.43(13)
108.70(14)
119.79(14)
134.31(15)
100.87(14)
115.30(14)
124.2(2)
73.44(13)
108.05(14)
121.72(14)
126.58(14)
107.43(14)
114.50(14)
126.8(2)
110.1(2)
116.7(2)
119.2(2)
123.0(2)
124.1(3)
0.88
N1–La–N4
N2–La–N3
N2–La–N4
N3–La–N4
La–N3–Si1
La–N3–Si2
114.7(2)
113.0(2)
La–N4–Si3
La–N4–Si4
123.2(2)
121.1(3)
Si1–N3–Si2
Si3–N4–Si4
Distance of La from N2C3
123.8(3)
0.758

D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
5185
NH2
R1
+ 2
R1
N
N
H
1. [Et3O]+[BF4]-
O
O
O
N
R2
H
2
H
N
N
2
R1
150 ˚C
R1
R2
R1
R1
2. Et3N,
H2N
R1
NH2
R1
5-fold excess
R2
R2
R1 R2
Me Me
NH2
H2N
[C2H4(BDIMes)2]H2
[C2H4(BDIDIPP)2]H2
H2N
NH2
iPr
H
[Cy(BDIMes)2]H2
[Cy(BDIDEP)2]H2
[Cy(BDIDIPP)2]H2
Me Me
Et
H
H
H2N
NH2
iPr
Scheme 2.
temperatures (70–95 ꢁC) and longer reaction times to
form complexes 5a and 5b. In general, all amine elimina-
tion reactions with linked bis(b-diketiminato) ligands re-
ported herein proceeded cleanly to the desired product
and no byproducts were observed. However, in some
cases the prolonged heating at high temperatures led to
some thermal decomposition.
Coincidentally, the 13C NMR spectra show six aromatic
carbon signals.
The sterically more demanding 2,6-diisopropylphenyl
substituents in 5a and 5b show hindered rotation in their
1H NMR spectra (Fig. 2). At elevated temperatures (60
ꢁC, toluene-d8) the spectra display the same Cs symme-
try as observed for complexes 3a, 3b and 4 at room tem-
perature. The NMR spectra of 5b at ꢁ20 ꢁC indicate a
C1 symmetric structure similar to that observed for the
cyclohexyl-linked complexes 6–10 (vide infra). The lar-
ger ionic radius in 5a reduces the barrier of rotation
and decoalescence to the C1 symmetric structure was
only observed at ꢁ60 ꢁC.
1
The H and 13C NMR spectra of ethylene-bridged
complexes 3a, 3b and 4 are in accordance with a Cs sym-
metric structure in solution on the NMR time scale, giv-
ing rise to one signal for the SiCH3 groups and the
methyne proton of the b-diketiminato ligand. The ethyl-
ene protons of 3a, 3b and 4 are split into two AAÕBBÕ
multiplets in the 1H NMR spectra. The aromatic mesityl
substituents give rise of two aromatic proton singlets
and two signals for the ortho mesityl methyl groups.
The cyclohexyl-bridged ligands [Cy(BDIMes)2]H2,
[Cy(BDIDEP)2]H2 and [Cy(BDIDIPP)2]H2 required higher
reaction temperatures and longer reaction times than the
SiXMe
N
Me XSi
2
2
[Ln{N(SiMe ) } ]
3 2 3
N
or
N
N
H
[La{N(SiHMe ) } (THF) ]
2 2 3
2
H
N
N
N
N
N
Ln
1
1
R
R
2
1
1
1
R
1
R
1
R
R
R
1
R
2
2
R
R
R
2
R
1
2
1
2
Ln
La Me Me Me
Me Me Me
R
R
X
R
R
Mes
[C H (BDI
) ]H
2 2
Me Me
iPr
3a
3b
4
5a
5b
2
4
DIPP
Y
[C H (BDI
) ]H
2 2
H
2
4
La Me Me
H
Me
Me
La iPr
iPr
H
H
Y
Scheme 3.

5186
D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
phatic solvents, the cyclohexyl-bridged complexes 6–10
are generally better soluble.
CH CN
3
SiCH
CHCH
*
3
3
60 ˚C
1
The H and 13C NMR spectra of cyclohexyl-bridged
complexes 6–9 show significant line broadening at room
temperature. At ꢁ20 ꢁC the spectra are in accordance
with a C1 symmetric structure in solution, similar to that
observed for the sterically more hindered diisopropyl-
phenyl substituted complex 10 at room temperature.
The spectra show two diastereomeric SiCH3 groups
and two different b-diketiminato groups. Both aromatic
rings are diastereotopic, giving rise of 12 signals in the
13C NMR spectra. Complexes 6 and 7 display six signals
for the mesityl methyl groups at low temperature,
whereas in the sterically more demanding diisopropyl-
phenyl substituted complex 10 all eight isopropyl methyl
groups are already at room temperature well separated
β-CH
CHCH
CH
3
2
0 ˚C
1
in the H and 13C NMR spectra.
X-ray crystallographic analyses of 3b, 7 and 8 con-
firmed their monomeric structure (Figs. 3–5). For better
comparison selected metrical parameters of 3b, 7 and 8
together with parameters of complex 5a and 10 [16]
are tabulated in Table 2.
-60 ˚C
CHCH
3
In complex 3b, yttrium is coordinated in a distorted
square pyramidal fashion, in which the amido ligand
occupies the apical position and the two linked b-dike-
timinato moieties form the basis. Similar to the lantha-
num complex 5a [16] both aromatic substituents have
a cisoid arrangement in 3b, pointing away from the api-
cal amido group, but the difference in the binding modes
of the two b-diketiminato moieties is significantly less
pronounced. The first b-diketiminato fragment compris-
ing of N1, N2 and C11–C13 is bonded in a g2 fashion,
analogous to the binding mode found in complex 1 and
other previously characterized mono(b-diketiminato)
complexes [14]. The yttrium atom is placed only 0.707
CH
CHCH
2
3
β-CH
5.0
4.0
3.0
2.0
1.0
(ppm)
Fig. 2. Temperature dependence of the 1H NMR spectrum of 5a in
toluene-d8 (*toluene-d0 impurity).
corresponding ethylene-bridged ligands, reflecting the
higher rigidity of the cyclohexyl linker in comparison
to the ethylene linker (Scheme 4). Whereas ethylene-
bridged complexes 3–5 are only slightly soluble in ali-
˚
A out of the N2C3 plane and both Y–N bonds are very
˚
similar (2.3522(17) and 2.3632(18) A). The other b-dike-
Me2XSi
SiXMe2
N
R2
[La{N(SiMe3)2}3]
N
N
H
R1
N
toluene, 65-95˚C
H
N
R1
N
N
N
La
or
R1
R1
N
R1
R1
R1
[La{N(SiHMe2)2}3(THF)2]
toluene, 25-65˚C
R1
R2
R2
R1 R2
Me Me
R2
R1 R2
Me Me Me
X
[Cy(BDIMes)2]H2
[Cy(BDIDEP)2]H2
[Cy(BDIDIPP)2]H2
6
7
8
9
Me Me
H
Me
H
Et
H
H
Et
Et
H
H
H
iPr
iPr
Me
10
Scheme 4.

D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
5187
Fig. 5. ORTEP diagram of the molecular structure of 8. Thermal
ellipsoids are drawn at the 50% probability level. Hydrogen atoms
have been omitted for the sake of clarity. For the disordered carbon
atoms C36B and C42B only one of the two independent positions is
shown.
Fig. 3. ORTEP diagram of the molecular structure of 3b. Thermal
ellipsoids are drawn at the 50% probability level. Hydrogen atoms
have been omitted for the sake of clarity.
timinato moiety, comprising of N3, N4 and C16–C18, is
˚
bound unsymmetrically with Y1–N3 (2.3065(17) A)
metal carbon distances in the lanthanum complex 5a
deviate much more dramatically (two independent mol-
˚
˚
being 0.1 A shorter than Y1–N4 (2.4098(17) A). Here
˚
ecules: 3.45–3.72 A vs. 3.01–3.18 A for molecule a, 3.54–
˚
˚
the yttrium is displaced by 1.163 A from the N2C3 plane.
The slightly different binding of the b-diketiminato moi-
eties is also reflected in the decreased yttrium to carbon
˚
3.84 A vs. 3.20–3.43 for molecule b). While the first
b-diketiminato moiety is virtually planar, with C13 devi-
˚
ating the most from the N2C3 plane (0.06 A), the second
b-diketiminato moiety is slightly more puckered (0.113
˚
A deviation for C18 from the N2C3 plane).
˚
distances (3.34–3.66 A for b-diketiminato group 1 vs.
˚
3.23–3.56 A for b-diketiminato group 2). Note that the
The mesityl substituents in 3b are p-stacked with a
˚
ring distance of 3.06–3.63 A and a dihedral angle be-
tween the planes of the aromatic rings of 12.9ꢁ. The yt-
trium amido bond (2.2843(17) A) is within the typical
˚
˚
range of Y–N bond lengths (2.18–2.32 A [23]), and the
amido ligand adopts a similar monoagostic interaction
as observed for 1.
The geometry of the linked bis(b-diketiminato) ligand
in 7, 8, as well as 10 [16], differs significantly from that
observed for 3b and 5a [16]. The two aromatic substitu-
ents are oriented in a transoid fashion in the cyclo-
hexyl-linked complexes, with one aromatic substituent
pointing away from the amido group and the other aro-
matic substituent pointing towards the amido group.
This significant change in ligand geometry is inflicted
by a slight decrease of the dihedral angle of the linker
unit (N2–C–C–N3) from 51.4(3) in 3b (respectively
49.3(4)ꢁ and ꢁ53.1(5)ꢁ for the two independent mole-
cules in 5a [16]) to ꢁ44.1(3) in 7, ꢁ41.5(2) in 8 and
42.25(19) in 10 [16].
Contrary to the findings for complex 3b and 5a, both
b-diketiminato moieties in complexes 7, 8 and 10 are
bound in the g5 bonding mode with the lanthanum
Fig. 4. ORTEP diagram of the molecular structure of 7. Thermal
ellipsoids are drawn at the 50% probability level. Hydrogen atoms
except for those attached to silicon have been omitted for the sake of
clarity.
˚
atom being displaced by 1.74–1.97 A out of the N2C3

5188
D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
Table 2
a
˚
˚
Selected bond lengths (A), atomic distances (A) and angles (ꢁ) for 3b, 5a, 7, 8 and 10
3b (Ln = Y)
5a (Ln = La)
7 (Ln = La)
8 (Ln = La)
10 (Ln = La)
Molecule a
Molecule b
Ln–N1
Ln–N2
2.3522(17)
2.3632(18)
2.3065(17)
2.4098(17)
2.2843(17)
3.6176(6)
3.3156(6)
3.337(2)
2.557(3)
2.536(3)
2.394(3)
2.559(3)
2.425(3)
3.6808(13)
3.5401(16)
3.483(3)
3.725(3)
3.446(3)
3.014(3)
3.162(3)
3.180(3)
2.540(3)
2.425(3)
2.573(3)
2.554(3)
2.426(3)
3.6819(12)
3.5818(13)
3.321(3)
3.429(3)
3.197(3)
3.538(3)
3.844(3)
3.547(3)
2.5154(16)
2.4554(16)
2.4574(16)
2.4729(16)
2.4128(17)
3.4643(6)
3.3574(6)
3.146(2)
2.5514(19)
2.4318(18)
2.481(2)
2.5518(18)
2.4310(18)
3.545(1)
3.615(1)
3.166(2)
3.122(2)
2.978(2)
3.022(3)
3.065(3)
3.078(2)
2.4977(15)
2.4340(14)
2.5063(15)
2.5939(15)
2.4543(15)
3.5756(5)
3.6631(6)
3.0554(18)
3.0469(18)
2.9690(17)
3.036(2)
Ln–N3
Ln–N4
Ln–N10
Lnꢀ ꢀ ꢀSi1
Lnꢀ ꢀ ꢀSi2
Lnꢀ ꢀ ꢀC11
Lnꢀ ꢀ ꢀC12
Lnꢀ ꢀ ꢀC13
Lnꢀ ꢀ ꢀC16
Lnꢀ ꢀ ꢀC17
Lnꢀ ꢀ ꢀC18
3.655(2)
3.351(2)
3.110(2)
2.9781(19)
3.0885(19)
3.184(2)
3.231(2)
3.560(2)
3.340(2)
3.153(2)
3.193(2)
3.1170(19)
N1–Ln–N2
N1–Ln–N3
N1–Ln–N4
N1–Ln–N10
N2–Ln–N3
N2–Ln–N4
N2–Ln–N10
N3–Ln–N4
N3–Ln–N10
N4–Ln–N10
Ln–N10–Si1
Ln–N10–Si2
Si1–N10–Si2
N2–C–C–N3
78.18(6)
147.55(7)
107.90(6)
103.92(6)
72.23(7)
72.33(9)
137.01(9)
119.95(9)
105.01(10)
65.47(9)
73.34(10)
114.97(9)
119.32(9)
114.96(9)
66.65(10)
136.97(10)
95.21(10)
71.17(9)
74.13(5)
135.70(5)
130.28(5)
95.42(6)
71.75(6)
98.50(7)
72.15(5)
98.27(5)
132.77(6)
125.06(6)
64.09(6)
132.85(5)
118.20(5)
63.72(5)
64.94(5)
96.67(5)
116.76(6)
101.27(6)
75.03(6)
112.93(9)
112.22(10)
72.06(9)
134.01(7)
97.35(6)
73.04(6)
133.85(5)
100.05(5)
73.45(5)
127.89(6)
72.71(5)
96.50(6)
94.76(6)
98.16(10)
123.36(9)
124.61(15)
116.90(15)
118.50(18)
49.3(4)
117.69(10)
111.81(9)
124.52(13)
118.55(14)
116.69(15)
ꢁ53.1(5)
125.44(7)
94.06(6)
133.96(5)
97.34(5)
134.19(6)
128.62(9)
111.31(8)
120.04(10)
51.4(3)
125.07(6)
114.75(9)
108.79(8)
136.33(11)
ꢁ44.1(3)
116.57(9)
120.53(9)
122.85(10)
ꢁ41.5(2)
117.31(8)
122.13(8)
120.47(9)
42.25(19)
Distance of Ln from N2C3
Ring 1
Ring 2
0.707
1.163
1.235
1.883
1.626
1.029
1.890
1.740
1.934
1.969
1.941
1.940
a
Structures 5a and 10 were reported in [16].
˚
planes and short Laꢀ ꢀ ꢀC contacts (2.97–3.19 A). The
The bis(dimethylsilyl)amido complex 7 displays a
weak b-SiH monoagostic interaction [19,21,24], as indi-
cated by one shorter Laꢀ ꢀ ꢀSi distance (3.3574(6) vs.
La–N bonds within the b-diketiminato moieties vary
˚
less dramatically (0.02 and 0.06 A for 7, 0.07 and
0.12 A for 8, 0.06 and 0.09 A for 10) than the 0.17 A
observed in 5a [16].
˚
˚
˚
˚
3.4643(6) A), a decreased La–N–Si angle (108.79(8)ꢁ
vs. 114.75(9)ꢁ) and
a
widened Si–N–Si angle
Table 3
Rare earth metal catalyzed copolymerization of CO2 and cyclohexene oxide
b
Mn
a
a
Cat.
[M]/[cat.]
p(CO2)
(atm)
T (ꢁC)
t (h)
TON
TOF
(hꢁ1
% Cyclic
carbonatea
% Carbonate
linkagesa
Mw
Mw/Mn
)
3a
5a
500
500
1000
900
500
600
500
500
500
500
500
500
1000
41
41
41
41
1
55
55
60
55
75
75
75
75
75
75
75
75
70
24
18
18
18
90
88
90
24
24
24
24
48
72
13
23
0.55
1.3
5
0
0
60
40
87
14
82
68
41
92
82
80
88
83
66
56700
72100
3940
6770
2240
3810
2540
7120
12000
8430
13500
11200
600
301000
197000
28800
97700
4730
5.3
2.7
7.3
14.4
2.1
2.8
3.4
1.5
1.4
1.8
1.6
1.6
7.4
6
[Y{N(SiMe3)2}3]
90
0
160
89
8.9
1.0
2.3
0.96
7.2
0
1
2b
10
5
1
204
86
10700
8520
3b
1
6
4
5a
1
173
251
159
304
292
62
4
10500
17200
15100
21800
18000
4420
1
10.5
6
6
1
6.6
12.7
6.1
5
8
10
1
5
1
8
17
[La{N(SiMe3)2}3]
1
0.86
a
Determined by 1H NMR spectroscopy.
Determined by gel permeation chromatography relative to polystyrene standards.
b

D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
5189
Table 4
Summary of crystallographic data of complexes 1 and 3b, 7 and 8
Complex
1
3b
7
8
Crystal data
Empirical formula
Formula weight
C35H65LaN4Si4
793.18
C36H58N5Si2Y
705.96
C38H62LaN5Si2
784.02
C42H68LaN5Si2
838.10
Crystal color, habit
Crystal dimensions (mm)
Crystal system
Yellow plate
0.15 · 0.10 · 0.10
Monoclinic
31.222(6)
12.426(3)
22.968(5)
90
Colorless block
0.35 · 0.30 · 0.20
Monoclinic
13.4080(2)
17.4103(2)
16.9623(3)
90
Colorless block
0.15 · 0.15 · 0.15
Triclinic
Colorless block
0.30 · 0.25 · 0.20
Triclinic
˚
a (A)
10.9150(2)
12.6095(2)
14.9986(2)
84.631(1)
12.076(2)
12.243(2)
˚
b (A)
˚
c (A)
16.157(3)
80.89(3)
a (ꢁ)
b (ꢁ)
c (ꢁ)
107.02(3)
90
103.3060(10)
90
84.263(1)
83.927(1)
73.68(3)
74.64(3)
3
˚
V (A )
8520(3)
P21/c
3853.34(10)
P21/c
2035.23(6)
ꢀ
2201.7(8)
ꢀ
Space group
Z
P1
P1
8
1.237
4
1.217
2
2
Dcalc (Mg/m3)
F(000)
1.279
820
1.139
1.264
880
1.058
3328
1.142
1504
1.606
l(Mo Ka) (mmꢁ1
)
Data collection
˚
k (Mo Ka radiation) (A)
Temperature (K)
0.71073
173(2)
0.71073
173(2)
0.71073
173(2)
0.71073
173(2)
h Range for data collection (ꢁ)
Number of total reflections
Number of unique reflections (Rint
1.8–27.5
36515
19500 (0.0805)
2.8–27.5
16629
8817 (0.0252)
2.2–27.5
17476
9293 (0.0153)
1.3–27.5
19749
10082 (0.0145)
)
Structure solution and refinement
Number of observations (I > 2r(I))
Data/restraints/parameters
Final R indices (I > 2r(I)); R1,wR2
Final R indices (all data); R1,wR2
Goodness-of-fit
10840
7090
8528
9251
19500/0/793
0.0530, 0.1111
0.1202, 0.1407
0.956
8817/0/413
0.0331, 0.0825
0.0494, 0.0925
0.837
9293/0/429
0.0246, 0.0638
0.0281, 0.0664
0.935
10082/2/471
0.0273, 0.0766
0.0309, 0.0797
1.022
3
˚
Maximum peak in final difference map (e/A )
3
Minimum peak in final difference map (e/A )
0.816
ꢁ0.699
0.361
ꢁ0.384
0.843
ꢁ0.850
0.949
ꢁ0.726
˚
(136.33(11)ꢁ). The geometry of the bis(trimethylsi-
lyl)amido ligand in lanthanum complexes 5a, 8 and 10
is less distorted than in the yttrium complex 3b with
Homoleptic trisamido complexes [Ln{N(SiMe3)2}3]
on the other hand produced either polymer with low
contents in carbonate linkages (Ln = Y) or significant
larger amount of cyclic carbonates (Ln = La).
˚
Laꢀ ꢀ ꢀSi distances greater than 3.54 A and La–N–Si an-
gles close to 120ꢁ.
2.3. Copolymerization of CO2 and cyclohexene oxide
3. Conclusion
Initial experiments indicate that the mono(b-diketim-
inato) complex as well as the bis(b-diketiminato) com-
plexes catalyze the copolymerization of cyclohexene
oxide and CO2 (Eq. (1)) at elevated temperatures with
moderate activity (Table 3). The highest carbonate
linkage contents of 92% was obtained with the ethylene-
bridged lanthanum complex 4. The mono(b-diketimi-
nato) complex 1 produced polycarbonate with up to
82% carbonate-linkages, but catalytic activity was lower.
No cyclic carbonates were formed at 41 atm CO2 and
55–60 ꢁC, but at lower CO2 pressure (1 atm) and higher
temperatures (70–75 ꢁC) all catalysts produced small
amounts (5–10%) of the cyclic carbonate byproduct.
The highest turnover frequency was observed for the
cyclohexyl-bridged complex 8 containing 2,6-diethyl-
phenyl substituents.
b-Diketiminato and novel linked bis(b-diketiminato)
rare earth metal complexes are accessible via a facile
amine elimination procedure. The complexes presented
here are the first homogeneous rare earth metal based
catalysts for epoxide/CO2 copolymerization with car-
bonate contents of up to 92%. Although catalyst activity
seems to be rather low in comparison to the most active
zinc or chromium based catalyst systems, we are hopeful
that tuning of the electronic and steric properties of the
highly modular linked bis(b-diketiminato) ligands will
lead to more active catalysts. We are exploring other lin-
ker units in order to better understand the factors gov-
erning the binding mode of the b-diketiminato ligands
in these systems. Furthermore, rare earth metal com-
plexes have proven to be very versatile polymerization
catalysts for a wide variety of non-polar and polar

5190
D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
monomers. Therefore, (block) copolymerization of such
non-polar or polar monomers in combination with
epoxide/CO2 copolymerization will give access to new
materials with highly attractive properties.
95.6 (b-CH), 29.0 (CH3CO), 20.9 (4-C6H2CH3), 18.8
(CH3CN), 18.1 (2-C6H2CH3).
4.3. Preparation of 4-((2,6-diisopropylphenyl)amino)-
pent-3-en-2-one [14m,26]
4. Experimental
Following the procedure reported for 4-((2,6-diethyl-
phenyl)amino)pent-3-en-2-one in [6d], 2,6-diisopro-
pylaniline (15.94 g, 90.1 mmol) and excess of
2,4-pentadione (56.9 g, 568 mmol) were added to a
round-bottom flask equipped with a stirring bar. A dis-
tillation apparatus was attached to collect water and the
neat solution was heated to 150 ꢁC for 24 h. Excess 2,4-
pentadione was removed in vacuo, and the residue was
distilled under vacuum to give a reddish solid, which
was crystallized from hexanes to give 12.57 g (54%) of
4.1. General procedures
All operations were performed under an inert atmo-
sphere of nitrogen or argon using standard Schlenk-line
or glovebox techniques. After drying over KOH, THF
was distilled from sodium benzophenone ketyl. Hex-
anes, pentane and toluene were purified by distillation
from sodium/triglyme benzophenone ketyl. Anhydrous
YCl3 (Aldrich) and LaCl3 (Strem) were used as received.
[Ln{N(SiMe3)2}3] (Ln = Y, La) [18], [Ln{N(SiH-
Me2)2}3(THF)2] (Ln = Y, La) [19], 4-((2,6-diethylphe-
nyl)amino)pent-3-en-2-one [6d] and (BDI)H [25] were
synthesized as described in the literature. Cyclohexene
oxide was dried by distillation from CaH2. All other
chemicals were commercially available and used as re-
ceived. 1H and 13C NMR spectra were recorded on Bru-
ker Avance 300 or Avance 400 spectrometer. Elemental
analyses were performed by the Microanalytical Labo-
ratory of this department. Although metal complexes
were combusted with V2O5 as burning aid, some analy-
ses gave low carbon content repeatedly, presumably due
to carbide formation. Molecular weights of the polycar-
bonates were determined by GPC (Agilent 1100 Series
using RI detector, 3 SDV Linear M 5lcolumns with
8 · 50 mm, 8 · 300 mm and 8 · 600 mm dimensions)
versus polystyrene standards using THF at 35 ꢁC as
eluent.
1
the aimed compound. H NMR (CDCl3, 400 MHz, 25
ꢁC): d = 12.04 (br s, 1H, NH), 7.27 (t, 3J = 7.7 Hz,
1H, 4-C6H3), 7.15 (d, J = 7.7 Hz, 1H, 3-C6H3), 5.19
3
3
(s, 1H, b-CH), 3.00 (sept, J = 6.9 Hz, 2H, CHCH3),
2.10 (s, 3H, CH3CO), 1.61 (s, 3H, CH3CN), 1.19 (d,
3J = 6.9 Hz, 6H, CHCH3), 1.12 (d, 3J = 6.8 Hz, 6H,
CHCH3); 13C{1H} NMR (CDCl3, 100.6 MHz, 25 ꢁC):
d = 195.9 (CO), 163.2 (CH3CN), 146.2, 133.5, 128.2,
123.5 (aryl), 95.5 (b-CH), 29.0 (CH3CO), 28.4
(CHCH3), 24.5 (CHCH3), 22.6 (CHCH3), 19.1
(CH3CN).
4.4. Preparation of [C2H4(BDIMes)2]H2
A solution of [Et3O]+[BF4]ꢁ (2.106 g, 11.09 mmol) in
CH2Cl2 (10 mL) was slowly added to a solution of 4-
((2,4,6-trimethylphenyl)-amino)pent-3-en-2-one (2.354
g, 10.83 mmol) in CH2Cl2 (15 mL) under a nitrogen
atmosphere. The mixture was stirred for 2.5 h at room
temperature. Et3N (1.5 mL) was added and the mixture
was stirred for another 5 min. A solution of ethylene
diamine (326 mg, 5.42 mmol) in Et3N (6 mL) was added
to the mixture and the stirring was continued overnight.
The solvent was removed in vacuo and the product was
extracted with toluene. [Et3NH]+[BF4]ꢁ was separated
as an oily precipitate. Toluene was removed in vacuo
and the residue was taken up in hexanes and cooled to
ꢁ20 ꢁC. The solid was separated by filtration and was
washed with ethanol to remove remaining starting mate-
rial. Yield 1.32 g (52%) of [C2H4(BDIMes)2]H2. 1H NMR
(C6D6, 400 MHz, 25 ꢁC): d = 10.90 (NH), 6.91 (s, 4H,
C6H2), 4.60 (s, 2H, b-CH), 2.72 (s, 4H, CH2), 2.23 (s,
6H, 4-C6H2CH3), 2.15 (s, 12H, 2-C6H2CH3), 1.62 (s,
6H, CH3), 1.60 (s, 6H, CH3); 13C{1H} NMR (C6D6,
100.6 MHz, 25 ꢁC): d = 166.5, 155.2 (CH3CN), 147.5,
131.2, 128.9, 127.7 (aryl), 94.3 (b-CH), 44.5 (CH2),
21.2 (CH3CNAr), 20.9 (4-C6H2CH3), 19.1 (CH3-
CNHCH2), 18.6 (2-C6H2CH3). Anal. Calc. for
C30H42N4 (458.68): C, 78.56; H, 9.23; N, 12.21. Found:
C, 78.39; H, 9.35; N, 12.27%.
4.2. Preparation of 4-((2,4,6-trimethylphenyl)amino)-
pent-3-en-2-one
Following the procedure reported for 4-((2,6-diethyl-
phenyl)amino)pent-3-en-2-one in [6d], 2,4,6-trimethyl-
aniline (13.17 g, 97.4 mmol) and excess of 2,4-pentadione
(68.0 g, 679 mmol) were added to a 250 mL round-
bottom flask equipped with a stirring bar. A distillation
apparatus was attached to collect water and the neat
solution was heated to 150 ꢁC for 24 h. Excess 2,4-pent-
adione was removed in vacuo, and the residue was
distilled under vacuum at 0.02 mmHg and 100–110 ꢁC
to give the desired compound. The obtained pale yellow
solid product was recrystallized from hexanes to give
1
18.30 g (86%). H NMR (CDCl3, 400 MHz, 25 ꢁC):
d = 11.82 (br s, 1H, NH), 6.87 (s, 2H, C6H2), 5.17 (s,
1H, b-CH), 2.25 (s, 3H, 4-C6H2CH3), 2.13 (s, 6H, 2-
C6H2CH3), 2.07 (s, 3H, CH3CO), 1.60 (s, 3H, CH3CN);
13C{1H} NMR (CDCl3, 100.6 MHz, 25 ꢁC): d = 195.8
(CO), 163.0 (CH3CN), 137.0, 135.7, 133.8, 128.8 (aryl),

D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
5191
4.5. Preparation of [C2H4(BDIDIPP)2]H2
128.0, 127.6 (aryl), 92.6 (b-CH), 58.0 (ring-CH), 33.4
(ring-CH2), 24.7 (ring-CH2), 21.2 (CH3CNAr), 20.7,
19.6, 18.5, 18.2 (CH3). Anal. calc. for C34H48N4
(512.77): C, 79.64; H, 9.44; N, 10.93. Found: C, 79.54;
H, 9.54; N, 11.03%.
A solution of [Et3O]+[BF4]ꢁ (3.836 g, 20.2 mmol) in
CH2Cl2 (10 mL) was added slowly to a solution of
4-((2,6-diisopropylphenyl)amino)-pent-3-en-2-one (5.22
g, 20.1 mmol) in CH2Cl2 (15 mL). The reaction mixture
was stirred for 3 h and then Et3N (2.8 mL) was added.
After 5 min a solution of ethylene diamine (0.736 g,
12.2 mmol) in Et3N (15 mL) was added to the mixture.
After stirring at room temperature for 16 h all volatiles
were removed in vacuo. Toluene was added to extract
the product from the oily precipitate of [Et3NH]+[BF4]ꢁ.
Toluene was removed and the crude product was dis-
solved in ethanol. Pale yellow crystals were obtained
after 12 h at ꢁ20 ꢁC. Drying in vacuo gave 4.192 g
4.7. Preparation of [Cy(BDIDEP)2]H2
A solution of [Et3O]+[BF4]ꢁ (4.910 g, 25.8 mmol) in
CH2Cl2 (20 mL) was added to a solution of 4-((2,6-
diethylphenyl)amino)-pent-3-en-2-one (5.693 g, 24.6
mmol) in CH2Cl2 (10 mL) under a nitrogen atmo-
sphere. After stirring for 3 h at room temperature
Et3N (3.4 mL) was added to the solution. The mixture
was stirred for another 15 min and trans-cyclohexane-
1,2-diamine (1.405 g, 12.3 mmol) in Et3N (15 mL) was
added. After stirring 16 h at room temperature all vol-
atiles were removed in vacuo. The residue was ex-
tracted with pentane (3 · 50 mL) and the extracts
were concentrated in vacuo. Addition of MeOH to
the solution resulted in precipitation of the product. The
product was filtered, washed with MeOH and dried
in vacuo to give 4.138 g (62%) of [Cy(BDIDEP)2]H2.
1H NMR (CDCl3, 400 MHz, 25 ꢁC): d = 10.93 (br s,
2H, NH), 7.07 (pt, 4H, 3-C6H3), 6.96 (pt, 2H, 4-
C6H3), 4.58 (s, 2H, b-CH), 3.14 (br s, 2H, ring-CH),
2.30–2.50 (m, 8H, CH2CH3), 1.95 (br s, 8H, CH3 and
ring-CH2), 1.66 (br m, 2H, ring-CH2), 1.60 (s, 6H,
1
(77%) of [C2H4(BDIDIPP)2]H2. H NMR (CDCl3, 400
MHz, 25 ꢁC): d = 10.93 (br s, 2H, NH), 7.09 (d,
3J = 7.2 Hz, 4H, 3-C6H2), 7.01 (m, 2H, 4-C6H2), 4.64
3
(s, 2H, b-CH), 3.29 (s, 4H, CH2), 2.82 (sept, J = 6.8
Hz, 4H, CHCH3), 1.95 (s, 6H, CH3CNAr), 1.61 (s,
6H, CH3CNHCH2), 1.13 (d, 12H, 3J = 6.8 Hz, CHCH3),
1.10 (d, 12H, 3J = 6.8 Hz, CHCH3); 13C{1H} NMR
(CDCl3, 100.6 MHz, 25 ꢁC): d = 166.2, 155.3 (CH3CN),
146.6, 138.1, 122.7, 122.6 (aryl), 93.8 (b-CH), 44.5
(CH2), 28.0 (CHCH3), 23.8 (CHCH3), 22.8 (CHCH3),
21.6 (CH3CNAr), 19.1 (CH3CNHCH2). Anal. calc. for
C36H54N4 (542.84): C, 79.65; H, 10.03; N, 10.32. Found:
C, 79.63; H, 9.99; N, 10.38%.
3
CH3), 1.19–1.35 (br m, 4H, ring-CH2), 1.15 (t, J = 7.6
4.6. Preparation of [Cy(BDIMes)2]H2
Hz, 6H, CH2CH3), 1.13 (t, 3J = 7.6 Hz, 12H, CH2CH3);
13C{1H} NMR (CDCl3, 100.6 MHz, 25 ꢁC): d = 166.2,
155.1 (CH3CN), 148.6, 133.8, 133.6, 125.7, 125.5,
122.1 (aryl), 92.8 (b-CH), 57.8 (ring-CH), 33.4 (ring-
CH2), 24.9 (CH2CH3), 24.5 (ring-CH2), 24.2 (CH2CH3),
21.5 (CH3CNAr), 19.5 (CH3CNHCH2), 14.29
(CH2CH3), 14.26 (CH2CH3). Anal. calc. for C36H52N4
(540.83): C, 79.95; H, 9.69; N, 10.36. Found: C, 79.90;
H, 9.75; N, 10.47%.
A solution of [Et3O]+[BF4]ꢁ (4.179 g, 22.00 mmol) in
CH2Cl2 (20 mL) was slowly added to a solution of 4-
(2,4,6-trimethylphenyl)-aminopent-3-en-4-one (5.222 g,
24.03 mmol) in CH2Cl2 (10 mL) under a nitrogen atmo-
sphere. The mixture was stirred for 2.5 h at room tem-
perature. Et3N (3.1 mL) was added to the clear pale
solution and the mixture was stirred for another 5
min.
A solution of trans-cyclohexane-1,2-diamine
(1.256 g, 11.01 mmol) in Et3N (15 mL) was added to
the reaction mixture and the stirring was continued
overnight. All volatiles were removed in vacuo and the
residue was extracted with pentane (2 · 20 mL) and tol-
uene (20 mL). The [Et3NH]+[BF4]ꢁ byproduct was sep-
arated from the organic solution as an oily precipitate
via decantation. The solvent was removed in vacuo
and the residue was taken up in pentane. Crystallization
at ꢁ20 ꢁC afforded 3.39 g (60%) of [Cy(BDIMes)2]H2. 1H
NMR (CDCl3, 300 MHz, 25 ꢁC): d = 11.03 (br s, 1H,
NH), 6.86 (s, 4H, C6H2), 4.56 (s, 2H, b-CH), 3.13 (br
s, 2H, ring-CH), 2.27 (s, 6H, 4-C6H2CH3), 2.01 (s, 6H,
2-C6H2CH3), 2.00 (s, 6H, 2-C6H2CH3), 1.90–1.98 (br
m, 2H, ring-CH2), 1.94 (s, 6H, CH3), 1.68 (m, 2H,
ring-CH2), 1.60 (s, 6H, CH3), 1.15–1.35 (m, 4H, ring-
CH2); 13C{1H} NMR (CDCl3, 75.5 MHz, 25 ꢁC):
d = 166.2, 155.2 (CH3CN), 147.2, 130.9, 128.3, 128.2,
4.8. Preparation of [Cy(BDIDIPP)2]H2
A 100 mL Schlenk flask was charged with 4-((2,6-
diisopropylphenyl)amino)-pent-3-en-2-one (5.46 g, 21.1
mmol). This was dissolved in CH2Cl2 (10 mL) and a
solution of [Et3O]+[BF4]ꢁ (3.80 g, 20.0 mmol) in CH2Cl2
(20 mL) was slowly added under nitrogen atmosphere.
After stirring for 3 h at room temperature, Et3N (2.02
g) was added slowly. The mixture was stirred for an-
other 15 min and then a solution of trans-cyclohexane-
1,2-diamine (1.142 g, 10.0 mmol) in Et3N (15 mL) was
added to the mixture. After stirring for 18 h at room
temperature all volatiles were removed in vacuo. The
product was extracted with hexanes and crystallized at
ꢁ20 ꢁC to afford 3.586 g (57%) of [Cy(BDIDIPP)2]H2.
1H NMR (CDCl3, 400 MHz, 25 ꢁC): d = 11.02 (br s,
2H, NH), 7.10 (m, 4H, 3-C6H3), 7.02 (pt, 2H, 4-C6H3),

5192
D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
4.61 (s, 2H, b-CH), 3.17 (br s, 2H, ring-CH), 2.90 (m,
4H, CHCH3), 1.98 (s, 6H, CH3), 1.90 (m, 2H, ring-
CH2), 1.61 (br s, 8H, CH3 and ring-CH2), 1.18-1.35
4.11. Preparation of [(BDI)Y{N(SiHMe2)2}2] (2b)
A 50 mL Schlenk flask was charged with (BDI)H (250
mg, 0.75 mmol) and [Y{N(SiHMe2)2}3(THF)2] (446 mg,
0.71 mmol). Hexanes (15 mL) was added and the reac-
tion mixture was stirred for 18 h at 40 ꢁC. The mixture
was filtered and the clear solution was concentrated and
cooled to ꢁ30 ꢁC. Compound 2b was obtained as color-
less crystals in 289 mg (59%) yield. 1H NMR (C6D6, 400
MHz, 25 ꢁC): d = 6.81 (s, 4H, C6H2), 5.21 (s, 1H, b-CH),
4.75 (sept, 3J = 3.0 Hz, 4H, SiH), 2.30 (s, 12H, 2-
C6H2CH3), 2.16 (s, 6H, 4-C6H2CH3), 1.58 (s, 6H,
3
(m, 4H, ring-CH2), 1.16 (d, 6H, J = 6.8 Hz, CHCH3),
1.14 (d, 6H, 3J = 6.6 Hz, CHCH3), 1.10 (d, 6H,
3J = 6.6 Hz, CHCH3) 1.09 (d, 6H, 3J = 6.8 Hz, CHCH3);
13C{1H} NMR (CDCl3, 100.6 MHz, 25 ꢁC) d = 166.6,
155.0 (CH3CN), 146.8, 138.3, 138.2, 122.7, 122.6,
122.5 (aryl), 92.9 (b-CH), 57.2 (ring-CH), 32.4 (ring-
CH2), 28.0 (CHCH3), 27.8 (CHCH3), 24.3 (ring-CH2),
24.0 (2 C, CHCH3), 23.1, 22.8 (CHCH3), 21.7
(CH3CNAr), 19.4 (CH3CNHCH2). Anal. calc. for
C40H60N4 (596.93): C, 80.48; H, 10.13; N, 9.39. Found:
C, 80.43; H, 10.26; N, 9.38%.
3
CH3CN), 0.16 (d, J = 3.0 Hz, 24H, SiCH3); 13C{1H}
NMR (C6D6, 100.6 MHz, 25 ꢁC): d = 167.3 (CH3CN),
144.1 (aryl-Cipso), 134.6, 131.9, 129.9 (aryl), 98.7 (b-
CH), 23.8 (CH3CN), 20.8 (4-C6H2CH3) 19.8 (2-
C6H2CH3), 2.9 (SiCH3). Anal. calc. for C31H57N4Si4Y
(688.07): C, 54.11; H, 8.35; N, 8.14. Found: C, 53.71;
H, 8.38; N, 7.88%.
4.9. Preparation of [(BDI)La{N(SiMe3)2}2] (1)
A Schlenk flask was charged with (BDI)H (35 mg,
0.105 mmol) and [La{N(SiMe3)2}3] (65 mg, 0.105
mmol). Toluene (0.5 mL) was added and the solution
was stirred at 115 ꢁC for 18 h. The solvent was removed
in vacuo to yield 82 mg (98%) of 1 as a pale yellow solid,
which was pure according to NMR spectroscopy. Crys-
tals suitable for X-ray analysis were grown from pentane
4.12. Preparation of [{C2H4(BDIMes)2}LaN(SiMe3)2]
(3a)
A
Schlenk flask was charged with [C2H4
1
solution at ꢁ20 ꢁC. H NMR (C6D6, 400 MHz, 25 ꢁC):
(BDIMes)2]H2 (459 mg, 1.00 mmol) and [La{N-
(SiMe3)2}3] (619 mg, 1.00 mmol). Hexanes (20 mL)
was added and the mixture was stirred at 60 ꢁC for 30
min. All volatiles were removed in vacuo to give 642
mg (85%) of 3a in form of a pale yellow powder, which
d = 6.81 (s, 4H, C6H2), 5.03 (s, 1H, b-CH), 2.28 (s, 12H,
2-C6H2CH3), 2.15 (s, 6H, 4-C6H2CH3), 1.56 (s, 6H,
CH3CN), 0.23 (s, 36H, SiCH3); 13C{1H} NMR (C6D6,
100.6 MHz, 25 ꢁC): d = 164.6 (CH3CN), 144.3 (aryl-
1
C
ipso), 134.6, 132.0, 130.1 (aryl), 96.8 (b-CH), 24.4
was clean according to NMR spectroscopy. H NMR
(CH3CN), 20.8 (4-C6H2CH3), 20.6 (2-C6H2CH3), 4.4
(SiCH3). Anal. calc. for C35H65LaN4Si4 (793.18): C,
53.00; H, 8.26; N, 7.06. Found: C, 52.82; H, 8.04; N,
6.79%.
(C6D6, 400 MHz, 25 ꢁC): d = 6.76 (s, 2H, C6H2), 6.66
(s, 2H, C6H2), 4.94 (s, 2H, b-CH), 3.82 (m, 2H, CH2),
3.35 (m, 2H, CH2), 2.18 (s, 6H, 4-C6H2CH3), 2.05 (s,
6H, 2-C6H2CH3), 1.93 (s, 6H, CH3CN), 1.52 (s, 6H, 2-
C6H2CH3), 1.47 (s, 6H, CH3CN), 0.33 (s, 18H, SiCH3);
13C{1H} NMR (C6D6, 100.6 MHz, 25 ꢁC): d = 163.3,
162.0 (CH3CN), 143.1 (aryl-Cipso), 133.8, 133.5, 133.3,
130.2, 129.8 (aryl), 97.3 (b-CH), 52.3 (CH2), 23.3, 23.0
(CH3CN), 20.9 (4-C6H2CH3), 20.3, 17.8 (2-C6H2CH3),
5.0 (SiCH3). Anal. calc. for C36H58LaN5Si2 (755.97):
C, 57.20; H, 7.73; N, 9.26. Found: C, 57.28; H, 7.75;
N, 8.97%.
4.10. Preparation of [(BDI)La{N(SiHMe2)2}2] (2a)
A Schlenk flask was charged with (BDI)H (336 mg,
1.00 mmol) and [La{N(SiHMe2)2}3(THF)2] (680 mg,
1.00 mmol). Hexanes (10 mL) was added and the reac-
tion mixture was stirred for 24 h at 25 ꢁC. The mixture
was filtered and the clear solution was concentrated in
vacuo to give 2a as a pale yellow powder (634 mg,
86%), which was clean according to NMR spectroscopy.
1H NMR (C6D6, 400 MHz, 25 ꢁC): d = 6.82 (s, 4H,
4.13. Preparation of [{C2H4(BDIMes)2}YN(SiMe3)2]
(3b)
3
C6H2), 5.11 (s, 1H, b-CH), 4.74 (sept, J = 3.0 Hz, 4H,
A Schlenk flask was charged with [C2H4(BDIMes)2]H2
(459 mg, 1.00 mmol) and [Y{N(SiMe3)2}3] (599 mg, 1.05
mmol). Toluene (10 mL) was added and the mixture was
stirred at 70 ꢁC for 24 h. All volatiles were removed in va-
cuo to give 697 mg (98%) of 3b in form of a pale yellow
powder, which was clean according to NMR spectros-
copy. Crystals suitable for X-ray analysis were grown
SiH), 2.29 (s, 12H, 2-C6H2CH3), 2.20 (s, 6H, 4-
3
C6H2CH3), 1.60 (s, 6H, CH3CN), 0.18 (d, J = 3.1 Hz,
24H, SiCH3); 13C{1H} NMR (C6D6, 100.6 MHz, 25
ꢁC): d = 164.6 (CH3CN), 142.9 (aryl-Cipso), 134.5,
131.9, 130.1 (aryl), 97.6 (b-CH), 23.5 (CH3CN), 20.8
(4-C6H2CH3), 19.6 (2-C6H2CH3), 2.7 (SiCH3). Anal.
calc. for C31H57LaN4Si4 (737.07): C, 50.52; H, 7.79; N,
7.60. Found: C, 49.85; H, 7.82; N, 7.16%.
1
from hexanes solution at ꢁ35 ꢁC. H NMR (C6D6, 400
MHz, 25 ꢁC): d = 6.67 (s, 4H, C6H2), 6.59 (s, 2H,

D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
5193
C6H2), 4.97 (s, 2H, b-CH), 3.73 (m, 2H, CH2), 3.30 (m,
2H, CH2), 2.19 (s, 6H, 4-C6H2CH3), 2.07 (s, 6H, 2-
C6H2CH3), 1.86 (s, 6H, CH3CN), 1.50 (s, 6H, CH3),
1.39 (s, 6H, CH3), 0.37 (s, 18H, SiCH3); 13C{1H}
NMR (C6D6, 100.6 MHz, 25 ꢁC): d = 165.1, 165.0
(CH3CN), 144.7 (aryl-Cipso), 133.8 (2 C), 129.94, 129.87
(aryl), 99.6 (b-CH), 51.7 (CH2), 23.5, 22.9 (CH3CN),
20.9 (4-C6H2CH3), 20.8, 18.0 (2-C6H2CH3), 5.7 (SiCH3).
Anal. calc. for C36H58N5Si2Y (705.97): C, 61.25; H, 8.28;
N, 9.92. Found: C, 61.08; H, 8.50; N, 9.70%.
6H, CH3), 1.51 (s, 6H, CH3), 1.14 (br d, 6H, CHCH3),
0.87 (br d, 12H, CHCH3), 0.70 (br d, 6H, CHCH3),
0.21 (s, 18H, SiCH3); 13C{1H} NMR (toluene-d8, 100.6
MHz, 80 ꢁC): d = 164.5, 161.6 (CH3CN), 146.8 (aryl-
Cipso), 143.3, 143.0, 125.4, 124.2, 124.0 (aryl), 96.9 (b-
CH), 52.1 (CH2), 28.8, 28.1 (CHCH3), 25.4 (CHCH3),
24.9 (CH3CN), 24.6, 24.5, 24.0 (CHCH3), 21.8
(CH3CN), 5.4 (SiCH3). Anal. calc. for C42H70LaN5Si2
(840.13): C, 60.05; H, 8.40; N, 8.34. Found: C, 59.48;
H, 8.32; N, 7.98%.
4.14. Preparation of [{C2H4(BDIMes)2}La-
N(SiHMe2)2] (4)
4.16. Preparation of [{C2H4(BDIDIPP)2}YN(SiMe3)2]
(5b)
A Schlenk flask was charged with [C2H4(BDIMes)2]H2
(460 mg, 1.00 mmol) and [La{N(SiMe2H)2}3(THF)2]
(682 mg, 1.00 mmol). Toluene (5 mL) was added and
the mixture was stirred at room temperature for 16 h.
All volatiles were removed in vacuo to give a pale yellow
powder. Crystallization from pentane at ꢁ35 ꢁC yielded
A Schlenk flask was charged with [C2H4(BDI-
DIPP)2]H2 (543 mg, 1.00 mmol) and [Y{N(SiMe3)2}3]
(570 mg, 1.00 mmol). Toluene (10 mL) was added and
the mixture was stirred at 95 ꢁC for 5 days. All volatiles
were removed in vacuo to give a reddish solid. Washing
with hexanes (2 · 3 mL) gave 377 mg of complex 5b as a
white powder. The hexanes washing solution was cooled
to ꢁ35 ꢁC for a few days, after which further 218 mg of
1
601 mg (82%) of 4 as pale yellow crystals. H NMR
(C6D6, 400 MHz, 25 ꢁC): d = 6.67 (s, 2H, C6H2), 6.56
3
1
(s, 2H, C6H2), 4.94 (s, 2H, b-CH), 4.88 (sept, J = 3.0
2b were isolated. Total yield: 595 mg (77%). H NMR
Hz, 2H, SiH), 3.79 (m, 2H, CH2), 3.43 (m, 2H, CH2),
2.18 (s, 3H, 4-C6H2CH3), 2.05 (s, 3H, 2-C6H2CH3),
1.92 (s, 3H, CH3CN), 1.66 (s, 3H, 2-C6H2CH3), 1.48
(s, 3H, CH3CN), 0.35 (d, 3J = 3.0 Hz, 12H, SiCH3);
13C{1H} NMR (C6D6, 100.6 MHz, 25 ꢁC): d = 163.4,
161.6 (CH3CN), 142.6 (aryl-Cipso), 133.3, 132.9, 132.5,
130.0, 129.8 (aryl), 97.2 (b-CH), 53.0 (CH2), 23.1, 22.8
(CH3CN), 21.0 (4-C6H2CH3), 19.4, 18.0 (2-C6H2CH3),
3.5 (SiCH3). Anal. calc. for C34H54LaN5Si2 (727.92):
C, 56.10; H, 7.48; N, 9.62. Found: C, 55.70; H, 7.71;
N, 9.32%.
(toluene-d8, 400 MHz, ꢁ20 ꢁC): d = 7.11 (m, 1H,
C6H3), 7.03 (m, 1H, C6H3), 6.92 (m, 1H, C6H3), 6.86
(dd, 3J = 7.3 Hz, 4J = 1.8 Hz, 1H, C6H3), 6.82 (dd,
3J = 6.3 Hz, 4J = 1.0 Hz, 1H, C6H3), 5.05 (s, 1H, b-
CH), 4.89 (s, 1H, b-CH), 3.65–3.73 (m, 3H, CH2 and
CHCH3), 3.49 (m, 1H, CHCH3), 2.92 (m, 3H, CH2
and CHCH3), 2.46 (m, 1H, CHCH3), 1.88 (s, 3H,
3
CH3), 1.86 (s, 3H, CH3), 1.45 (d, J = 6.6 Hz, CHCH3),
1.39 (s, 3H, CH3CN), 1.35 (m, 6H, CH3CN and
3
CHCH3), 1.11 (d, J = 6.1 Hz, 3H, CHCH3), 1.10 (d,
3J = 6.3 Hz, 3H, CHCH3), 0.91 (d, 3J = 6.8 Hz, 3H,
3
CHCH3), 0.89 (d, J = 6.8 Hz, 3H, CHCH3), 0.38 (s,
4.15. Preparation of [{C2H4(BDIDIPP)2}LaN(SiMe3)2]
(5a)
18H, SiCH3), 0.32 (d, J = 6.6 Hz, 3H, CHCH3), 0.25
3
(d, 3J = 6.6 Hz, 3H, CHCH3); 13C{1H} NMR (tolu-
ene-d8, 100.6 MHz, ꢁ20 ꢁC): d = 167.5, 167.3, 164.0,
162.8 (CH3CN), 148.2, 147.7 (aryl-Cipso), 143.8, 143.6,
143.3, 142.5, 126.1, 125.7, 125.0, 124.5, 124.4, 124.0
(aryl), 100.4, 99.1 (b-CH), 53.8, 49.0 (CH2), 29.7, 29.3,
28.1, 27.4 (CHCH3), 26.2, 26.1, 25.9, 25.4, 25.1, 24.8,
24.5 (2 C), 24.3, 24.2, 23.9, 21.3 (CH3), 6.4 (SiCH3).
Anal. calc. for C42H70N5Si2Y (790.13): C, 63.85; H,
8.93; N, 8.86. Found: C, 62.75; H, 8.57; N, 8.42%.
A Schlenk flask was charged with [C2H4(BDI-
DIPP)2]H2 (544 mg, 1.00 mmol) and [La{N(SiMe3)2}3]
(621 mg, 1.00 mmol). Toluene (10 mL) was added and
the mixture was stirred at 72 ꢁC for 110 h. All volatiles
were removed in vacuo to give 718 mg (80%) of 5a in
form of a pale yellow powder, which was clean accord-
ing to NMR spectroscopy. Crystals suitable for X-ray
analysis [16] could be grown from hexanes solution at
ꢁ35 ꢁC. 1H NMR (toluene-d8, 400 MHz, 25 ꢁC):
d = 7.00 (m, 4H, 3-C6H3), 6.91 (m, 2H, 4-C6H3), 4.95
(s, 2H, b-CH), 3.76 (m, 2H, CH2), 3.26 (br m, 4H,
CH2 and CHCH3), 2.71 (m, 2H, CHCH3), 1.92 (s, 6H,
CH3), 1.50 (s, 6H, CH3), 1.14 (br d, 6H, CHCH3),
0.87 (br d, 12H, CHCH3), 0.70 (br d, 6H, CHCH3),
4.17. Preparation of [{Cy(BDIMes)2}LaN(SiMe3)2]
(6)
A Schlenk flask was charged with [Cy(BDIMes)2]H2
(513 mg, 1.00 mmol) and [La{N(SiMe3)2}3] (622 mg,
1.00 mmol). Toluene (10 mL) was added and the mix-
ture was stirred for 24 h at 65 ꢁC. All volatiles were re-
moved in vacuo to give a pale yellow powder. A small
amount of impurities was removed by washing with hex-
anes (5 mL) to yield 667 mg (82%) of clean 6. 1H NMR
1
0.21 (s, 18H, SiCH3); H NMR (toluene-d8, 400 MHz,
80 ꢁC): d = 6.84–7.08 (m, 6H, C6H3), 4.92 (s, 2H, b-
CH), 3.81 (br m, 2H, CH2), 3.33 (br m, 2H, CH2),
3.20 (m, 2H, CHCH3), 2.70 (m, 2H, CHCH3), 1.93 (s,

5194
D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
(toluene-d8, 400 MHz, ꢁ20 ꢁC): d = 6.88 (s, 1H, C6H2),
6.82 (s, 2H, C6H2), 6.74 (s, 1H, C6H2), 5.10 (s, 1H, b-
CH), 4.25 (s, 1H, b-CH), 4.21 (m, 1H, ring-CH), 3.09
(m, 1H, ring-CH), 2.45 (s, 3H, CH3), 2.38 (s, 3H,
CH3), 2.30 (m, 2H, ring-CH2), 2.21 (s, 6H, CH3), 2.10
(s, 3H, CH3), 2.06 (s, 3H, CH3), 1.73 (s, 3H, CH3),
1.64 (s, 3H, CH3), 1.58 (m, 2H, ring-CH2), 1.54 (s, 3H,
CH3), 1.41 (s, 3H, CH3), 1.05–1.30 (m, 4H, ring-CH2),
0.23 (s, 18H, SiCH3); 13C{1H} NMR (toluene-d8, 100.6
MHz, ꢁ20 ꢁC): d = 162.6, 161.12, 161.08, 159.7
(CH3CN), 147.4, 147.0 (aryl-Cipso), 132.5, 131.7, 130.5,
130.0, 129.9, 129.6, 129.4, 129.2, 129.1, 129.0 (aryl),
94.5, 88.2 (b-CH), 71.7, 64.7 (ring-CH), 33.3, 32.6,
25.8, 25.6 (ring-CH2), 23.9, 23.8, 23.2, 21.2, 21.04,
20.99, 20.7, 18.5, 18.1 (CH3), 4.6 (SiCH3). Anal. calc.
for C40H64LaN5Si2 (810.06): C, 59.31; H, 7.96; N,
8.65. Found: C, 59.12; H, 7.81; N, 8.48%.
1.01 mmol). Toluene (10 mL) was added and the mix-
ture was stirred for 40 h at 95 ꢁC. All volatiles were re-
moved in vacuo, the residue was dissolved in pentane
(10 mL) and filtered. The filtrate was concentrated in va-
cuo to yield 793 mg (95%) of 8 as a pale yellow powder.
Crystals suitable for X-ray analysis were grown from
1
hexanes solution at ꢁ35 ꢁC. H NMR (toluene-d8, 400
MHz, ꢁ20 ꢁC): d = 6.98–7.15 (m, 6H, C6H3), 5.10 (s,
1H, b-CH), 4.17 (m, 1H, ring-CH), 4.14 (s, 1H, b-
CH), 3.27 (m, 1H, CH2CH3), 3.08 (m, 1H, ring-CH),
2.78 (m, 1H, CH2CH3), 2.68 (m, 2H, CH2CH3), 2.58
(m, 1H, CH2CH3), 2.44 (m, 1H, CH2CH3), 2.31 (m,
1H, ring-CH2), 2.12 (m, 1H, CH2CH3), 2.04 (s, 3H,
CH3CN), 2.01 (m, 1H, CH2CH3), 1.64 (s, 3H, CH3CN),
1.56–1.65 (br m, 4H, ring-CH2, obscured by other sig-
nal), 1.51 (s, 3H, CH3CN), 1.40 (t, 3J = 7.4 Hz, 3H,
3
CH2CH3), 1.34 (s, 3H, CH3CN), 1.28 (t, J = 7.4 Hz,
3H, CH2CH3), 1.20 (t, 3J = 7.6 Hz, 3H, CH2CH3),
1.1–1.3 (m, 3H, ring-CH2, obscured by other signals),
1.09 (t, 3J = 7.5 Hz, 3H, CH2CH3), 0.19 (br s, 18H,
SiCH3); 13C{1H} NMR (toluene-d8, 100.6 MHz, ꢁ20
ꢁC): d = 162.5, 161.3, 161.0, 160.0 (CH3CN), 149.1,
148.5 (aryl-Cipso), 136.0, 135.3, 134.9, 134.8, 126.2,
125.5, 124.8, 124.4, 124.3, 123.5 (aryl), 94.4, 87.8 (b-
CH), 71.8, 64.6 (ring-CH), 33.1, 32.7 (ring-CH2), 27.7
(CH2CH3), 25.73, 25.68 (ring-CH2), 25.4 (CH2CH3),
23.9 (2 C, CH2CH3 and CH3CN), 23.6, 23.4 (CH3CN),
22.9 (CH2CH3), 21.1 (CH3CN), 14.4, 14.3, 13.3, 12.9
(CH2CH3), 4.6 (SiCH3). Anal. calc. for C42H68LaN5Si2
(838.11): C, 60.19; H, 8.18; N, 8.36. Found: C, 59.95;
H, 8.25; N, 8.15%.
4.18. Preparation of [{Cy(BDIMes)2}LaN(SiHMe2)2]
(7)
A Schlenk flask was charged with [Cy(BDIMes)2]H2
(256 mg, 0.500 mmol) and [La{N(SiHMe2)2}3(THF)2]
(340 mg, 0.500 mmol). Toluene (5 mL) was added and
the mixture was stirred for 60 h at room temperature.
All volatiles were removed in vacuo. The residue was
treated with hexanes, which caused the product to precip-
itate. Filtration and drying in vacuo gave 370 mg (95%) of
complex 7 as a pale yellow powder. Crystals suitable for
X-ray analysis were grown from hexanes solution at ꢁ35
ꢁC. 1H NMR (toluene-d8, 400 MHz, ꢁ20 ꢁC): d = 6.84 (s,
1H, C6H2), 6.81 (s, 1H, C6H2), 6.78 (s, 1H, C6H2), 6.76 (s,
3
1H, C6H2), 4.96 (s, 1H, b-CH), 4.81 (sept, J = 2.8 Hz,
4.20. Preparation of [{Cy(BDIDEP)2}LaN(SiHMe2)2]
(9)
2H, SiH), 4.41 (s, 1H, b-CH), 4.15 (m, 1H, ring-CH),
3.29 (m, 1H, ring-CH), 2.39 (s, 3H, Me), 2.33 (m, 1H,
ring-CH2), 2.21 (s, 6H, 2-C6H2CH3), 2.18 (s, 6H, 2-
C6H2CH3), 2.04 (s, 3H, CH3), 1.90 (s, 3H, CH3), 1.72
(m, 1H, ring-CH2), 1.66 (s, 3H, CH3), 1.63 (s, 3H,
CH3), 1.62 (m, 3H, ring-CH2, obscured by other signal),
1.53 (s, 3H, CH3), 1.15–1.35 (m, 4H, ring-CH2), 0.26 (d,
3J = 2.8 Hz, 6H, SiCH3), 0.04 (d, 3J = 2.8 Hz, 6H,
SiCH3); 13C{1H} NMR (toluene-d8, 100.6 MHz, ꢁ20
ꢁC): d = 162.1, 160.9, 160.7, 160.4 (CH3CN), 147.0,
146.0 (aryl-Cipso), 132.5, 132.1, 130.9, 130.6, 129.7,
129.6, 129.2 (br, 2 C), 129.00, 128.95 (aryl), 93.9, 89.3
(b-CH), 70.6, 64.4 (ring-CH), 33.6, 32.6, 25.9, 25.6,
(ring-CH2), 24.3, 23.4, 22.7, 21.3, 21.1 (2 C), 20.4, 20.2,
18.8, 18.4 (CH3), 3.6, 3.1 (SiCH3). Anal. calc. for
C38H60LaN5Si2 (782.00): C, 58.37; H, 7.73; N, 8.96.
Found: C, 57.97; H, 7.93; N, 8.60%.
A Schlenk flask was charged with [Cy(BDIDEP)2]H2
(550 mg, 1.02 mmol) and [La{N(SiHMe2)2}3(THF)2]
(857 mg, 1.26 mmol). Toluene (10 mL) was added and
the mixture was stirred for 51 h at 65 ꢁC. All volatiles
were removed in vacuo, the residue was dissolved in hex-
anes (2.5 mL). Crystallization at ꢁ35 ꢁC produced 738
mg (90%) of 9 after a few days in form of pale yellow
crystals. 1H NMR (toluene-d8, 400 MHz, ꢁ20 ꢁC):
d = 6.96–7.13 (m, 6H, C6H3), 4.96 (s, 1H, b-CH), 4.75
3
(sept, J = 2.8 Hz, 2H, SiH), 4.31 (s, 1H, b-CH), 4.07
(m, 1H, ring-CH), 3.28 (m, 1H, ring-CH), 2.83 (m,
2H, CH2CH3), 2.67 (m, 2H, CH2CH3), 2.52 (m, 2H,
CH2CH3), 2.32 (m, 2H, CH2CH3 and ring-CH2) 2.17
(m, 1H, CH2CH3), 2.01 (s, 3H, CH3CN), 1.67 (s, 3H,
CH3CN), 1.60 (s, 3H, CH3CN), 1.57–1.74 (br m, 4H,
ring-CH2, obscured by other signals), 1.49 (s, 3H,
CH3CN), 1.15–1.38 (br m, 3H, ring-CH2 obscured by
other signals), 1.35 (pt, 3J = 7.3 Hz, 3H, CH2CH3),
4.19. Preparation of [{Cy(BDIDEP)2}LaN(SiMe3)2]
(8)
3
3
1.32 (pt, J = 7.3 Hz, 3H, CH2CH3), 1.27 (pt, J = 7.6
Hz, 3H, CH2CH3), 1.10 (pt, 3J = 7.5 Hz, 3H, CH2CH3),
A Schlenk flask was charged with [Cy(BDIDEP)2]H2
(540 mg, 1.00 mmol) and [La{N(SiMe3)2}3] (624 mg,
3
3
0.22 (d, J = 2.8 Hz, 6H, SiCH3), ꢁ0.03 (d, J = 2.8 Hz,

D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
5195
6H, SiCH3); 13C{1H} NMR (toluene-d8, 100.6 MHz,
ꢁ20 ꢁC): d = 162.2, 160.8 (CH3CN), 160.7 (2 C,
CH3CN), 148.9, 148.0 (aryl-Cipso), 136.5, 136.0, 134.8,
134.7 (aryl), 126.8, 126.4, 124.9, 124.3, 124.2, 123.8
(aryl), 93.2, 88.2 (b-CH), 71.0, 64.5 (ring-CH), 33.2,
32.7 (ring-CH2), 26.6 (CH2CH3), 25.8, 25.7 (ring-CH2),
25.2, 25.0, 24.4 (CH2CH3), 24.0, 23.6, 22.8, 21.5
(CH3CN), 15.0, 14.2, 14.1, 13.2 (CH2CH3), 3.5, 3.2
(SiCH3). Anal. calc. for C40H64LaN5Si2 (810.06): C,
59.31; H, 7.96; N, 8.65. Found: C, 58.23; H, 7.99; N,
8.27%.
on a Nonius KappaCCD area detector. Cell parameters
were obtained from 10 frames using a 10ꢁ scan and re-
fined with 18958 reflections for 1, 8799 reflections for
3b, 8875 reflections for 7 and 10074 reflections for 8.
Lorentz, polarization, and empirical absorption correc-
tions were applied [27a,27b]. The space groups were
determined from systematic absences and subsequent
least-squares refinement. The structures were solved by
direct methods. The parameters were refined with all
data by full-matrix least-squares on F2 using SHELXL-97
[27c]. Hydrogen atoms were fixed in idealized positions
using a riding model. Non-hydrogen atoms were refined
anisotropically. The methyl groups attached to C36A
and C42A in complex 8 are disordered and were refined
with two independent positions (position occupation of
80:20 for C36B/C36C and 70:30 for C42B/C42C). Scat-
tering factors and Df0 and Df00 values were taken from
the literature [27d].
4.21. Preparation of [{Cy(BDIDIPP)2}LaN(SiMe3)2]
(10)
A Schlenk flask was charged with [Cy(BDIDIPP)2]H2
(602 mg, 1.01 mmol) and [La(N(SiMe3)2)3] (625 mg,
1.01 mmol). Toluene (10 mL) was added and the mix-
ture was stirred for 4 days at 95 ꢁC. All volatiles were
removed in vacuo to give 707 mg (79%) of 10 as a pale
yellow powder. Crystals suitable for X-ray analysis [16]
4.23. Typical high pressure procedure for the
copolymerization of cyclohexene oxide and CO2
1
could be grown from hexanes solution at ꢁ35 ꢁC. H
NMR (C6D6, 400 MHz, 25 ꢁC): d = 7.02–7.18 (m, 6H,
C6H3), 5.17 (s, 1H, b-CH), 4.22 (s, 1H, b-CH), 4.20
(m, 1H, ring-CH), 3.50 (sept., 3J = 6.8 Hz, 1H, CHCH3),
3.16 (m, 1H, ring-CH), 3.14 (sept., 3J = 6.8 Hz, 1H,
The steel autoclave was loaded in the glovebox with
catalyst 6 (33.0 mg, 40.7 lmol), cyclohexene oxide
(4.00 g, 40.8 mmol) and a stirring bar. The vessel was re-
moved from the glovebox and pressurized to 41 atm
CO2. The reactor was then heated with stirring to 60
ꢁC for 18 h. Excess cyclohexene oxide was then removed
in vacuo. The polymer was redissolved in CH2Cl2 and
dried in vacuo at 60 ꢁC until constant weight. Yield:
507 mg. The carbonate linkage content was determined
from the intensity of the cyclohexyl methyne proton sig-
nals (4.6 ppm for carbonate linkages, 3.3 ppm for ether
3
CHCH3), 3.05 (sept., J = 6.8 Hz, 1H, CHCH3), 2.54
(sept., 3J = 6.8 Hz, 1H, CHCH3), 2.30 (m, 1H, ring-
CH2), 2.05 (s, 3H, CH3CN), 1.75 (s, 3H, CH3CN),
1.64 (s, 3H, CH3CN), 1.50–1.70 (m, 6H, ring-CH2, ob-
scured by other signals), 1.54 (d, 3J = 6.8 Hz, 3H,
3
CHCH3), 1.47 (s, 3H, CH3CN), 1.42 (d, J = 6.8 Hz,
3
3H, CHCH3), 1.34 (d, J = 7.1 Hz, 3H, CHCH3), 1.27
(d, 3J = 6.8 Hz, 3H, CHCH3), 1.21 (d, 3J = 6.6 Hz,
3H, CHCH3), 1.10–1.14 (m, 1H, ring-CH2, obscured
by other signal), 1.13 (d, 3J = 6.8 Hz, 3H, CHCH3),
1.04 (d, 3J = 6.8 Hz, 3H, CHCH3), 0.94 (d, 3J = 6.8
Hz, 3H, CHCH3), 0.28 (s, 9H, SiCH3), 0.03 (s, 9H,
SiCH3); 13C{1H} NMR (C6D6, 100.6 MHz, 25 ꢁC):
d = 164.9, 161.4, 160.4, 160.3 (CH3CN), 148.0, 147.3
(aryl-Cipso), 141.4, 141.1, 140.8, 140.6, 124.9, 124.1,
124.0, 123.9, 123.8, 123.0 (aryl), 95.3, 87.1 (b-CH),
71.5, 65.2 (ring-CH), 33.3, 32.7 (ring-CH2), 31.4, 29.3,
27.9, 27.4 (CHCH3), 27.0, 26.0 (CHCH3), 25.8, 25.7
(ring-CH2), 25.1, 25.0 (CHCH3), 24.9 (2 C, CH3CN),
24.49, 24.47 (ring-CH2), 24.0, 23.5 (CHCH3), 23.3,
21.4 (CH3CN), 5.0, 2.6 (SiCH3). Anal. calc. for
C46H76LaN5Si2 (894.22): C, 61.79; H, 8.57; N, 7.83.
Found: C, 60.77; H, 8.67; N, 7.43%.
linkages) in the H NMR spectrum of the polymer.
1
4.24. Typical normal pressure procedure for the
copolymerization of cyclohexene oxide and CO2
A Schlenk flask was loaded with the catalyst 6 (32.6
mg, 40.2 lmol) and a stirring bar. Toluene (1 mL) was
added to dissolve the catalyst and the nitrogen atmo-
sphere was exchanged for 1 atm CO2. After 5 min stir-
ring, cyclohexene oxide (4.135 g, 42.1 mmol) was
added via syringe. A CO2-filled balloon was attached
and the mixture was stirred at 75 ꢁC for 24 h. The sol-
vent and excess cyclohexene oxide was then removed
in vacuo. The polymer was redissolved in CH2Cl2 and
dried in vacuo at 60 ꢁC until constant weight. Yield:
533 mg.
4.22. X-ray crystal structure analysis of 1, 3b, 7 and 8
5. Supporting information
Clear, colorless crystals suitable for X-ray diffraction
analysis were obtained by cooling of a concentrated pen-
tane solution to ꢁ20 ꢁC (for 1), respectively from hex-
anes at ꢁ35 ꢁC (for 3b, 7 and 8). Data were collected
Crystallographic data (excluding structure factors)
for the structure of complexes 1, 3b, 7 and 8 reported
in this paper have been deposited with Cambridge

5196
D.V. Vitanova et al. / Journal of Organometallic Chemistry 690 (2005) 5182–5197
(b) M. Cheng, D.R. Moore, J.J. Reczek, B.M. Chamberlain, E.B.
Lobkovsky, G.W. Coates, J. Am. Chem. Soc. 123 (2001) 8738;
(c) D.R. Moore, M. Cheng, E.B. Lobkovsky, G.W. Coates,
Angew. Chem. Int. Ed. 41 (2002) 2599;
Crystallographic Data Centre as supplementary publica-
tion nos. CCDC-262007 for 1, CCDC-262008 for 3b,
CCDC-266998 for 7 and CCDC-266997 for 8. Copies
of the data can be obtained free of charge from the
Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (int code) +44 1223 336 033 or e-mail:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk.
(d) D.R. Moore, M. Cheng, E.B. Lobkovsky, G.W. Coates, J.
Am. Chem. Soc. 125 (2003) 11911.
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Acknowledgments
(b) C.-S. Tan, T.-J. Hsu, Macromolecules 30 (1997) 3147;
(c) B. Liu, X. Zhao, X. Wang, F. Wang, J. Polym. Sci. A 39
(2001) 2751;
Generous financial support by the Deutsche
Forschungsgemeinschaft (DFG SPP 1166) and the
Fonds der Chemischen Industrie is gratefully acknowl-
edged. K.C.H. is a DFG Emmy Noether fellow (2001–
2005) and thanks Professor John A. Gladysz for his
generous support. We are indebted to Prof. J. Okuda
and Dr. K. Beckerle (RWTH Aachen) for GPC
measurements.
(d) Z. Quan, X. Wang, X.J. Zhao, F.S. Wang, Polymer 44 (2003)
5605.
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