Rare earth metal bis(alkyl) complexes bearing amino phosphine ligands: Synthesis and catalytic activity toward ethylene polymerization

Article abstract of DOI:10.1016/j.jorganchem.2007.07.022

Reactions of neutral amino phosphine compounds HL^1-3 with rare earth metal tris(alkyl)s, Ln(CH₂SiMe₃)₃(THF)₂, afforded a new family of organolanthanide complexes, the molecular structures of which are strongly dependent on the ligand framework. Alkane elimination reactions between 2-(CH₃NH)-C₆H₄P(Ph)₂ (HL¹) and Lu(CH₂SiMe₃)₃(THF)₂ at room temperature for 3 h generated mono(alkyl) complex (L¹)₂Lu(CH₂SiMe₃)(THF) (1). Similarly, treatment of 2-(C₆H₅CH₂NH)-C₆H₄P(Ph)₂ (HL²) with Lu(CH₂SiMe₃)₃(THF)₂ afforded (L²)₂Lu(CH₂SiMe₃)(THF) (2), selectively, which gradually deproportionated to a homoleptic complex (L²)₃Lu (3) at room temperature within a week. Strikingly, under the same condition, 2-(2,6-Me₂C₆H₃NH)-C₆H₄P(Ph)₂ (HL³) swiftly reacted with Ln(CH₂SiMe₃)₃(THF)₂ at room temperature for 3 h to yield the corresponding lanthanide bis(alkyl) complexes L³Ln(CH₂SiMe₃)₂(THF)_n (4a: Ln = Y, n = 2; 4b: Ln = Sc, n = 1; 4c: Ln = Lu, n = 1; 4d: Ln = Yb, n = 1; 4e: Ln = Tm, n = 1) in high yields. All complexes have been well defined and the molecular structures of complexes 1, 2, 3 and 4b-e were confirmed by X-ray diffraction analysis. The scandium bis(alkyl) complex activated by AlEt₃ and [Ph₃C][B(C₆F₅)₄], was able to catalyze the polymerization of ethylene to afford linear polyethylene.

Full text of DOI:10.1016/j.jorganchem.2007.07.022

Journal of Organometallic Chemistry 692 (2007) 4943–4952
www.elsevier.com/locate/jorganchem
Rare earth metal bis(alkyl) complexes bearing amino phosphine
ligands: Synthesis and catalytic activity toward
ethylene polymerization
a
a,
a
a
Shihui Li a,b, Wei Miao a,b, Tao Tang , Dongmei Cui *, Xuesi Chen , Xiabin Jing
a
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences,
Changchun 130022, China
b
Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
Received 11 June 2007; received in revised form 8 July 2007; accepted 10 July 2007
Available online 26 July 2007
Abstract
Reactions of neutral amino phosphine compounds HL1–3 with rare earth metal tris(alkyl)s, Ln(CH2SiMe3)3(THF)2, afforded a new
family of organolanthanide complexes, the molecular structures of which are strongly dependent on the ligand framework. Alkane elim-
ination reactions between 2-(CH3NH)-C6H4P(Ph)2 (HL1) and Lu(CH2SiMe3)3(THF)2 at room temperature for 3 h generated
mono(alkyl) complex (L1)2Lu(CH2SiMe3)(THF) (1). Similarly, treatment of 2-(C6H5CH2NH)-C6H4P(Ph)2 (HL2) with Lu(CH2Si-
Me3)3(THF)2 afforded (L2)2Lu(CH2SiMe3)(THF) (2), selectively, which gradually deproportionated to a homoleptic complex (L2)3Lu
(3) at room temperature within a week. Strikingly, under the same condition, 2-(2,6-Me2C6H3NH)-C6H4P(Ph)2 (HL3) swiftly reacted
with Ln(CH2SiMe3)3(THF)2 at room temperature for 3 h to yield the corresponding lanthanide bis(alkyl) complexes L3Ln(CH2Si-
Me3)2(THF)n (4a: Ln = Y, n = 2; 4b: Ln = Sc, n = 1; 4c: Ln = Lu, n = 1; 4d: Ln = Yb, n = 1; 4e: Ln = Tm, n = 1) in high yields. All
complexes have been well defined and the molecular structures of complexes 1, 2, 3 and 4b–e were confirmed by X-ray diffraction anal-
ysis. The scandium bis(alkyl) complex activated by AlEt3 and [Ph3C][B(C6F5)4], was able to catalyze the polymerization of ethylene to
afford linear polyethylene.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Lanthanide; Alkyl complex; Ethylene; Polymerization; Phosphine
1. Introduction
nyl environment and their derivatives [4]. Heteroatom com-
pounds have attracted more and more attention recently
due to their strong metal–ligand bonds and exceptional
and tunable steric and electronic features required for com-
pensating coordinative unsaturation of metal centers and
catalytic activity toward polymerization. The majority of
the proceeding studies involves chelating ligands such as
bidentate amidinates [5], guanidinates [6], b-diketiminates
[7], salicylaldiminates [8], etc. Whereas, formation of sol-
vent or salt adduct, dimerization or ligand redistribution
hinder the isolation of rare earth metal alkyl complexes
especially bis(alkyl) complexes supported by such hetero-
atom compounds. Until recently, some N,N-bidentate
ligands with exclusively ‘‘hard’’ donors, have been success-
fully introduced by Hessen’s and Piers’ groups, respectively,
Rare earth metal alkyl complexes have gathered upsurge
in research interest in the past decade, because they are
highly active single component catalysts or crucial precur-
sors of the cationic counterparts under the activation of
MAO or borate toward olefin polymerizations [1] and
highly regio- or stereoselective polymerizations of conju-
gated monomers [2] and polar monomers [3]. The ancillary
ligands being attempted to stabilize rare earth metal alkyl
species, up to date, have been dominated by cyclopentadie-
*
Corresponding author. Tel.: +86 431 85262773; fax: +86 431
85263773.
E-mail address: dmcui@ciac.jl.cn (D. Cui).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.07.022

4944
S. Li et al. / Journal of Organometallic Chemistry 692 (2007) 4943–4952
1)
n
THF
BuLi
H
to stabilize bis(alkyl) complexes based on ‘‘hard’’ Lewis
acidic rare earth metal centers [9]. The auxiliaries containing
sterically demanding and ‘‘soft’’ phosphine electron donors,
preferred to stabilize more acidic metal center, have been
applied in transition metal chemistry. Fryzuk and co-work-
ers have shown that zirconium complexes supported by
multidentate amido phosphine ligands that contain –
CH2SiMe2– back-bone are capable of nitrogen activation
[10]. The o-phenylene-derivatives of amido-phosphine
ligands reported by Liang [11] have been proved to be more
robust in palladium complexes that are highly active to
Heck reaction and Suzuki coupling, which was also intro-
duced to support alkali metal complexes by Izod [12]. How-
ever, organolanthanide complexes bearing ‘‘soft’’ electronic
donor of phosphine have remained less explored, as rare
earth metal ions favor to coordinate to hard donors.
Recently, rare earth metal halide or amido complexes sup-
ported by flexible bis(phosphineimino)methanids have been
investigated by Roesky group [13]. Izod reported a rare
earth metal iodide complex supported by donor-functional-
ized phosphide ligand, whereas, the sequential alkylation of
metal iodide arouses deprotonation [14]. Up to date suc-
cessfully isolated lanthanide dialkyl complexes are stabi-
lized by P,N-multidentate ligands [15]. Our group also
demonstrated that P,N-bidentate phosphino aldiminates
are good candidates to stabilize bis(alkyl) species with six-
membered-metallocycle coordination, and the isolated
complexes are efficient initiators for the ring-opening poly-
merization of lactide [16]. Here we wish to report the syn-
thesis of a series of lanthanide mono- or bis(alkyl)
complexes bearing N-arylated or N-alkylated amino-phos-
phine auxiliaries, which combined with metal ion to gener-
ate rigid five-membered-metallocycle coordination. The
polymerization of ethylene initiated by the scandium
bis(alkyl) species in the presences of aluminum tris(alkyl)s
and organoborate was also presented.
R
N
NH2
Lu(CH2SiMe3)3THF2
2) RCl
PPh2
PPh2
toluene
rt, 3 h
HL1: R = CH3
HL2: R = CH2C6H5
Ph2P
R
R
Si
N
N
N
N
toluene, rt, 6 d
Lu
Lu
PPh2
PPh2
N
PPh
PPh2
2O
1: (L1)2LuCH2SiMe3
2: (L2)2LuCH2SiMe3
3: (L2)3Lu
Scheme 1. Synthesis of complexes 1–3.
Switching to the bulky ligand HL2, the major product
isolated from the reaction was also mono(alkyl), [2-
(C6H5CH2N)-C6H4P(Ph)2]2LuCH2SiMe3(THF) (2). X-ray
diffraction analysis defined that complex 2 was a monomer,
adopting twisted tetragonal bipyramidal geometry with the
alkyl carbon and phosphorous atoms axial and the THF
oxygen and two nitrogen and a phosphorous atoms equa-
torial (Table 1, Fig. 1). The ligand coordinated to the lute-
tium ion in a bidentate mode. Complex 2 was unstable in
solution at room temperature and slowly transferred to a
homoleptic complex [2-(C6H5CH2N)-C6H4P(Ph)2]3Lu (3)
within a week due to ligand redistribution. In complex 3,
all three ligands bonded to the metal ion with the chelated
P and N atoms in bidentate modes and located around the
central metal uniformly to generate trigonal bipyramidal
geometry with the metal atom being the apex. No solvated
THF was observed in the molecule (Fig. 2). The bond
˚
˚
lengths of Lu–P (av. 2.953(4) A for 2, av. 2.922(3) A for
3), Lu–N (av. 2.230(14) A for 2, av. 2.236(8) A for 3) and
Lu–C (2.326(18) A) were comparable to those literature
˚
˚
˚
2. Results and discussion
data [15,16], which did not need to discuss further (Tables
2 and 3).
2.1. Syntheses and characterization of complexes
2.1.2. Synthesis and characterization of complexes 4a–e
We noted that the N-alkylated amino phosphines HL1
and HL2 could not support the highly unsaturated rare
earth metal bis(alkyl) species because of their flexibility
and deficit in spacial sterics. Thus, the rigid N-arylated
compound 2-(2,6-Me2C6H3NH)-C6H4P(Ph)2 (HL3) [11h]
was chosen to react with 1 equiv of yttrium tris(alkyl)s,
Y(CH2SiMe3)3(THF)2, anticipated to generate the corre-
sponding bis(alkyl) complex. The reaction performed
smoothly at room temperature in toluene, leading to the
isolation of the expected L3Y(CH2SiMe3)2(THF)2 (4a). It
2.1.1. Synthesis and characterization of complexes 1–3
The reaction of Lu(CH2SiMe3)3(THF)2 and an equiva-
lent of neutral N-alkylated amino phosphine, (2-diphenyl-
phosphinophenyl)-N-(methyl)aniline (HL1) was carried out
in toluene at room temperature and kept stirring for 3 h.
Removal of volatiles gave pale yellow residue, which was dis-
solved by a mixture of toluene and hexane. Pale yellow solid
was isolated from the above mixture after cooled at À30 ꢁC
for 24 h. However, it was not the expected bis(alkyl) product
but a mono(alkyl) complex, [2-(CH3N)-C6H4P(Ph)2]2LuCH-
2SiMe3(THF) (1). The 1H NMR and 13C NMR spectra were
indicative for the formation of complex 1 according to the
loss of the signal for amino proton of the ligand around d
4.98 and the appearance of resonances of methylene protons
of LuCH2Si(CH3)3 that shifted downfield compared to that
in Lu(CH2SiMe3)3(THF)2 (Scheme 1).
1
was evident from the H NMR spectrum that 4a was a
monomer of bis(alkyl)s stabilized by mono-anionic L3 frag-
ment combined with two THF moieties. The resonances at
d À0.21 were assignable to the methylene protons of the
2 equiv metal alkyl species YCH2SiMe3, whilst those at d

S. Li et al. / Journal of Organometallic Chemistry 692 (2007) 4943–4952
4945
Table 1
Summary of crystallographic data for 2, 3 and 4b–e
2
3
4b
4c
4d
4e
Formula
C58H61N2OP2SiLu
1067.09
Monoclinic
P21/c
13.9822(13)
23.079(2)
17.5630(16)
90
106.810(2)
90
5425.3(9)
4
C75H63N3P3Lu
1274.16
Triclinic
C44H67NOPSi2Sc
758.11
Monoclinic
P21/c
10.5599(9)
21.5029(18)
19.5639(16)
90
94.478(2)
90
4428.8(6)
4
1.137
0.288
1640
C44H67NOPSi2Lu
888.11
Monoclinic
P21/c
10.5804(7)
21.7161(14)
19.5813(13)
90
94.9800(10)
90
4482.1(5)
4
1.316
2.323
1840
C44H67NOPSi2Yb
886.18
Monoclinic
P21/c
10.5672(6)
21.7677(13)
19.6496(12)
90
94.6670(10)
90
4504.9(5)
4
1.307
2.196
1836
C38H53NOPSi2Tm
795.89
Monoclinic
P21/c
10.5563(7)
21.7753(14)
19.7009(13)
90
94.5570(10)
90
4514.3(5)
4
1.171
2.078
1632
Formula weight
Crystal system
Space group
ꢀ
P1
˚
a (A)
15.0977(13)
16.4812(14)
17.1770(15)
71.1310(10)
76.4280(10)
88.057(2)
3927.4(6)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
Dcalc (g/cm3)
1.306
1.940
2184
1.077
1.354
1300
l (mmÀ1
F(000)
)
Number of observed
reflections
10669
14853
8711
8789
8848
8864
Number of parameters
refined
654
739
461
431
461
405
Goodness-of-fit
R1
wR2
1.017
0.1011
0.2231
1.044
0.0646
0.1375
0.901
0.0594
0.1256
0.901
0.0384
0.0821
1.046
0.0274
0.0678
1.144
0.0529
0.1835
Fig. 1. X-ray structure of 2 with 35% probability of thermal ellipsoids.
Hydrogen atoms are omitted for clarity.
Fig. 2. X-ray structure of 3 with 35% probability of thermal ellipsoids.
Hydrogen atoms are omitted for clarity.
1.37 and d 3.72 were arising from the coordinated two THF
molecules. Whereas, the repeated attempt to isolate single
crystals of 4a was failed. Monitoring the reaction by using
NMR technique found that 4a was unstable at room tem-
perature. The signal of the methylene protons disappeared
completely within 6 h, suggesting that 4a transferred to
unknown products.
Fortunately, employing Sc(CH2SiMe3)3(THF)2, the sim-
ilar reaction with HL3 afforded the anticipated phosphide
scandium bis(alkyl)s, L3Sc(CH2SiMe3)2(THF) (4b), quanti-
tatively. The yellow crystals of 4b grew from a mixture of
toluene/hexane at À30 ꢁC in 24 h. In addition, treatments
of the corresponding lutetium, ytterbium and thulium tri-
s(alkyl)s with HL3, respectively, afforded the analogous
complexes L3Ln(CH2SiMe3)2(THF) (4c: Ln = Lu; 4d:
1
Ln = Yb; 4e: Ln = Tm) (Scheme 2). The H NMR spectra
of 4b and 4c had similar pattern to that of 4a. The methy-
lene protons of LuCH2SiMe3 species displaying a signal at
d À0.30 downfield shifted compared to d À0.60 in Lu(CH2-
SiMe3)3(THF)2. The resonance for methylene protons of
ScCH2SiMe3 unit showed at much lower field d 0.31, which
overlapped with silylmethyl (SiMe3) protons. It was note-
worthy that 4b or 4c was bonded by one THF molecule dif-
ferent from 4a with two THF coordination. Both 4b and 4c

4946
S. Li et al. / Journal of Organometallic Chemistry 692 (2007) 4943–4952
Table 2
axial (av. P–Lu–O = 168.77ꢁ, Table 4) and the two alkyl
carbon atoms and nitrogen atom of the ligand occupied
the equatorial positions (Fig. 3, complex 4b) [17]. The cen-
tral metal ion sit out of the CCN plane with a distance of
˚
Selected bond lengths (A) and angles (ꢁ) from 2
Lu–N(1)
Lu–N(2)
Lu–C(49)
Lu–O
Lu–P(1)
Lu–P(2)
2.230(11)
2.219(13)
2.333(17)
2.353(11)
2. 985(4)
2.917(4)
˚
˚
˚
˚
0.207 A for 4b, 0.248 A for 4c, 0.251 A for 4d and 0.261 A
for 4e, respectively, which were in contrast to complexes 2
and 3 where the Lu atom deviated from the CCN plane with
˚
˚
much longer distance of 0.8387 A for 2 and 0.9367 A for 3,
which might be attributed to the crowded environment of
metal centers. Interestingly, the rigid five-membered ring
PC2NLn was planar and almost perpendicular to the
CCN plane with a dihedral angle 90.8ꢁ for 4b, 91.6ꢁ for
4c, 90.6ꢁ for 4d and 91.6ꢁ for 4e, respectively. Whereas
N(1)–Lu–C(49)
N(2)–Lu–C(49)
N(1)–Lu–P(1)
N(2)–Lu–P(2)
C(49)–Lu–P(1)
C(51)–Lu–P(2)
104.4(6)
103.9(6)
67.5(3)
67.2(3)
99.7(5)
163.5(5)
in
a closely related phosphine aldiminato complex
[o-(PPh2)C6H4CH2NC6H3Me2-2,6]Lu(CH2SiMe3)2(THF)
[16], the six-membered metallacycle NC(9)C2PLn is much
twisted due to the flexible feature of the ligand. The binding
angle of amido phosphine ligand (P–Ln–N) was close to
each other in complexes 4c–e averaging 68.81ꢁ, but a larger
angle was found in 4b (72.12(7)ꢁ). This angle was compara-
ble to those in complexes containing such rigid five-mem-
bered metallacycle, such as 67.46(3)ꢁ in complex 2,
67.4(2)ꢁ in 3 and 65.83(7)ꢁ in (PNPPh)Lu(CH2SiMe3)2
(THF) [15b], but smaller than 77.8(1)ꢁ in Sc(CH2Si-
Me3)2[N(SiMe2CH2PPri2)2] bearing flexible five-membered
metallacycle [15a] and 78.53(7)ꢁ in L2-MeLu(CH2SiMe3)2-
(THF) containing six-membered metallacycle [16]. The
C–Ln–C bond angles averaging 111.8ꢁ in complexes 4b–e
were slightly larger than 103.50(12)ꢁ [15b] found in the
above mentioned complexes, which were comparable to
those of C–Sc–C (113.5(2)ꢁ) [15a] and C–Y–C (119.5(2)ꢁ)
in THF solvated amidinato yttrium bis(alkyl) complex
[18], indicating the similar steric environment of the ligands.
However, these bond angles were larger than those of
C–Ln–C in the rare earth metal bis(alkyl) complexes sup-
ported by triazacyclononane (99.41(8)ꢁ) [19], triamino-
amide (101.96(6)ꢁ) [20] and b-diketiminate (108.90(13)ꢁ) [21].
Table 3
˚
Selected bond lengths (A) and angles (ꢁ) from 3
Lu(1)–N(2)
Lu(1)–N(3)
Lu(1)–N(1)
Lu(1)–P(2)
Lu(1)–P(3)
Lu(1)–P(1)
2.220(8)
2.243(8)
2.246(8)
2.906(3)
2.921(3)
2.940(3)
N(2)–Lu(1)–N(3)
N(2)–Lu(1)–N(1)
N(3)–Lu(1)–N(1)
N(2)–Lu(1)–P(2)
N(3)–Lu(1)–P(3)
N(1)–Lu(1)–P(1)
103.8(3)
107.2(3)
107.9(3)
68.0(2)
67.1(2)
67.2(2)
Si
(THF)n
N
P
NH
Ln(CH2SiMe3)3THF2
Ln
PPh2
toluene/hexane, rt, 2-4 h
Si
Ph2
HL3
4a: L3Y(CH2SiMe3)2(THF)2, n = 2
4b: L3Sc(CH2SiMe3)2(THF), n = 1
4c: L3Lu(CH2SiMe3)2(THF), n = 1
4d: L3Yb(CH2SiMe3)2(THF), n = 1
4e: L3Tm(CH2SiMe3)2(THF), n = 1
2.2. Catalysis on ethylene polymerization
Designing rare earth metal complexes possessing cata-
lytic activity for ethylene polymerization has been an goal
of organolanthanide chemists. Ansa-lanthanocene alkyls,
linked and non-linked half-sandwich lanthanide hydro-
carbyls [1,2g,h,k,9c,d], and the recent amidinato (non-
metallocene) rare earth metal bis(alkyl)s [18,22] have been
explored to exhibit high reactivity toward olefin
polymerization.
Thus, these amido phosphine ligated rare earth metal
bis(alkyl) complexes were investigated whether to have
such performance. Complexes 4c–e were inert even at
the presences of both activators [Ph3C][B(C6F5)4] and
AlEt3 (Table 5, entries 1–3). Whereas strikingly, complex
4b based on more Lewis acidic scandium ion was active at
20 ꢁC and 1 bar of ethylene. The influences of the reaction
conditions on the polymerization were investigated. At
40 ꢁC, the catalytic activity of 4b reached to 49000 g/
Scheme 2. Synthesis of complexes 4a–e.
were stable without ligand redistribution in solution, which
was probably attributed to the smaller ionic radii of Sc and
Lu ions compared to that of Y ion. All complexes 4a–c
were Cs symmetric in solution as the metal alkyl protons
were equivalent. Complexes 4d and 4e did not give infor-
mative 1H NMR spectra due to their paramagnetic nature.
X–ray diffraction analysis solved the overall molecular
structures of complexes 4b–e to be isomeric monomers.
Each metal ion was chelated by N,P atoms of the phosphide
ligand in bidentate mode, and a solvated THF molecule and
two alkyl species locating in cis-positions, to generate dis-
torted trigonal bipyramidal geometry around the metal cen-
ter. The phosphorus donor and the THF molecule were

S. Li et al. / Journal of Organometallic Chemistry 692 (2007) 4943–4952
4947
Table 4
˚
Selected bond lengths (A) and angles (ꢁ) from 4b–e
4b (Ln = Sc)
4c (Ln = Lu)
4d (Ln = Yb)
4e (Ln = Tm)
Ln–N
Ln–O
Ln–C(35)
Ln–C(31)
Ln–P
2.131(3)
2.175(2)
2.210(3)
2.240(3)
2.8319(10)
2.236(3)
2.268(3)
2.312(4)
2.359(4)
2.9289(11)
2.239(2)
2.295(2)
2.357(3)
2.328(3)
2.9474(7)
2.243(6)
2.301(5)
2.332(8)
2.362(8)
2.9597(19)
N–Ln–C(35)
N–Ln–C(31)
C(35)–Ln–C(31)
N–Ln–P
C(35)–Ln–P
C(31)–Ln–P
O–Lu–P
123.95(11)
120.84(11)
112.55(13)
72.12(7)
91.84(9)
91.13(9)
124.51(14)
119.97(14)
112.08(16)
69.26(9)
92.29(12)
91.60(11)
168.03(8)
120.69(10)
124.47(10)
111.31(11)
68.87(6)
91.89(8)
92.37(8)
124.6(3)
120.1(3)
111.4(3)
68.29(16)
92.3(2)
91.8(2)
168.84(15)
169.89(7)
168.31(6)
(mol Ln bar h), which was more than double of that
(22000 g/(mol Ln bar h)) at 20 ꢁC. Meanwhile the molecu-
lar weight of the resultant polyethylene (PE) was also
increased and the molecular weight distribution did not
change obviously. Whereas, increasing the temperature
to 50 ꢁC, the molecular weight of PE lowered significantly
and the molecular weight distribution became wider,
although the activity dropped slightly. If the polymeriza-
tion was performed at much higher temperature (60 ꢁC),
both catalytic activity and molecular weight of PE
decreased greatly, which could be attributed to the
decomposition of the complex and the rapid chain trans-
fer reaction at high temperature (Table 5, entries 5–8). It
was reasonable that prolonged reaction time would
arouse high yield of PE. Almost no polymer could be iso-
lated if the reaction time was shorter than 10 min, how-
ever, the catalytic activity decreased if polymerization
carried out longer than 30 min (Table 5, entries 9–11).
Fig. 3. X-ray structure of 4b with 35% probability of thermal ellipsoids.
Hydrogen atoms are omitted for clarity.
Table 5
Polymerization of ethene under various conditionsa
Entry
Cat
Temperature (ꢁC)
t (min)
t (min) (Al + Cat)
Yield (g)
Activityd (·10À4
)
Men (·10À3
)
Mw (·10À3
)
Mw/Mn
1
2
3
4
5
6
7
8
9
10
11
12
13b
14c
4c
4d
4e
4b
4b
4b
4b
4b
4b
4b
4b
4b
4b
4b
20
20
20
20
30
40
50
60
40
40
40
40
50
40
30
30
30
30
30
30
30
30
10
20
30
30
30
30
5
5
5
5
5
0
0
0
0.22
0.37
0.49
0.41
0.30
0.03
0.13
0.18
0.31
1.10
0.24
2.2
3.7
4.9
4.1
3.0
162.4
225.8
253.5
89.7
433.3
560.6
589.7
535.5
173.0
2.67
2.48
2.33
5.97
10.96
5
10
60
5
60
60
10
5
15.8
2.0
1.8
3.1
4.4
2.4
14.8
20.5
139.6
138.2
97.5
157.1
199.8
575.6
592.2
437.2
10.61
9.73
4.12
4.29
4.49
5
Conditions:
a
Toluene 20 mL, catalyst: 20 lmol, AlEt3: 100 lmol, [Ph3C][B(C6F5)4]: 20 lmol, 1 bar ethylene pressure unless otherwise noted.
5 bar ethylene pressure.
AlEt3: 50 lmol.
b
c
d
e
g(PE)/(mol Ln bar h).
Determined by GPC 220 type high-temperature chromatograph equipped with three PLgel 10 lm Mixed-B LS type columns. 1,2,4-Trichlorobenzene
(TCB) was employed as the solvent at a flow rate of 1.0 mL/min. The calibration was made by polystyrene standard EasiCal PS-1 (PL Ltd).

4948
S. Li et al. / Journal of Organometallic Chemistry 692 (2007) 4943–4952
Varying the ethylene pressure from 1 to 5 bar increased
the yield of PE obviously whereas which seemed to have
less influence on the activity (Table 5, entries 7 and 13).
In contrast, AlEt3-to-borate ratio affected the perfor-
mance of 4b. When the value was decreased from 5:1 to
2.5:1, the catalytic activity halved (Table 5, entries 6
and 14). To our surprise, an increase of the activation
time of complex 4b by AlEt3 led to obvious drop in activ-
ity of 4b and significantly broadened the molecular weight
distribution (Table 5, entries 7–12). This suggested that at
long activation time some unknown less active species
were formed. It was also noteworthy when the reaction
medium contained minimum amount of THF, the cata-
lytic system 4b/AlEt3/[Ph3C][B(C6F5)4] lost its activity
for ethylene polymerization completely. This might be
explained that the strong electron donor THF intended
to occupy the blank space of the cationic central metal
ion to prohibit the coordination of non-polar ethylene
monomer [18].
the presence of 5 equiv aluminum triethyls, was active
toward ethylene polymerization with modest activity at
room temperature under normal pressure to give linear
polyethylene.
4. Experimental
4.1. General methods
All reactions were carried out under a dry and oxygen-
free argon atmosphere by using Schlenk techniques or
under a nitrogen atmosphere in an MBRAUN glovebox.
All solvents were purified from MBRAUN SPS system.
Organometallic samples for NMR spectroscopic measure-
ments were prepared in the glovebox by use of NMR tubes
sealed by paraffin film. 1H, 13C NMR spectra were recorded
on a Bruker AV400 or AV600 (FT, 400 MHz for 1H;
1
100 MHz for 13C or FT, 600 MHz for H; 150 MHz for
13C) spectrometer. NMR assignments were confirmed by
1
1
Based on the polymerization results, the mechanism of
polymerization and the roles of the three components
could be described as follow. When 4b was treated with
[Ph3C][B(C6F5)4], cationic species L3Sc+(CH2SiMe3)-
the H–1H COSY and H–13C HMQC experiments when
necessary. The NMR spectra of the polyethylene were
recorded on a Varian Unity 400 MHz spectrometer with
o-dichlorobenzene as the solvent at 120 ꢁC. IR spectra were
recorded on VERTEX 70 FT-IR or IFS66V/S FTIR. The
molecular weight and the polydispersitiy of the polymer
samples were determined at 150 ꢁC by a PLGPC 220 type
high-temperature chromatograph equipped with three
PLgel 10 lm Mixed-B LS type columns. 1,2,4-Trichloro-
benzene (TCB) was employed as the solvent at a flow rate
of 1.0 mL/min. The calibration was made by polystyrene
standard EasiCal PS-1 (PL Ltd). Elemental analyses were
performed at National Analytical Research Centre of
Changchun Institute of Applied Chemistry (CIAC). (2-
Diphenylphosphino) aniline and (2-diphenylphosphinophe-
nyl)-N-(methyl) aniline (HL1) were prepared according to
the literature [25]. N-(2-Diphenylphosphinophenyl)-2,6-
dimethylaniline was prepared according to the literature
[11h].
1
(THF) were generated as shown in the H NMR spectrum
according to the release of Ph3CCH2SiMe3 [2h,k], which
were the initiation species. However, the cationic units
showed no activity at the absence of AlEt3 in contrast
to the previous reported systems [2h,k,22d]. This could
be attributed to the coordination of THF molecule and
too electron negative nature of the ligand, which inhibited
the coordination and insertion of non-polar ethylene
monomer. Thus, the addition of AlEt3 activated the cat-
ionic units, which could be explained that AlEt3 extruded
the impurities in the system, abstracted the coordinated
THF molecule and stabilized the cationic metal center
[9c,d,23].
According to Mandelken’s protocol and the reported
result [24], all of the corresponding carbon resonances in
high-temperature 13C NMR spectrum were assigned unam-
biguously, in which there were no signals for the branches,
indicating linear microstructure of the isolated
polyethylene.
4.2. X-ray crystallographic studies
Crystals for X-ray analysis were obtained as described
in the preparations. The crystals were manipulated in a
glovebox. Data collections were performed at À86 ꢁC
on a Bruker SMART APEX diffractometer with a
CCDC area detector, using graphite monochromated
3. Conclusion
A series of amido phosphine supported organolantha-
nide complexes have been prepared by treatment of rare
earth metal tris(alkyl)s with the neutral amido phosphine
compounds via alkane elimination. The N-alkylated amido
phosphine ligand bonded to the central metal to generate a
twisted flexible five-membered metallocycle to stabilize rare
earth metal mono(alkyl) species. Whereas, the N-arylated
amido phosphine ligand formed a rigid five-membered
metallocyclic coordination, which was able to support rare
earth metal bis(alkyl) units. Moreover, the resultant
bis(alkyl) complex based on more Lewis acidic scandium
ion, upon activation with equimolar [Ph3C][B(C6F5)4] in
˚
Mo K radiation (k = 0.71073 A). The determination of
crystal class and unit cell parameters was carried out
by the SMART program package. The raw frame data were
processed using SAINT and SADABS to yield the reflection
data file. The structures were solved by using SHELXTL
program. Refinement was performed on F2 anisotropi-
cally for all non-hydrogen atoms by the full-matrix
least-squares method. The hydrogen atoms were placed
at the calculated positions and were included in the struc-
ture calculation without further refinement of the
parameters.

S. Li et al. / Journal of Organometallic Chemistry 692 (2007) 4943–4952
4949
4.3. Syntheses of complexes
m-P(C6H5)2, m-NC6H4P, p-PC6H5), 7.43–7.47 (m, 8H,
o-P(C6H5)2). 13C NMR (100 MHz, C6D6, 25 ꢁC): d 4.93
(s, 3C, SiMe3), 25.58 (s, 2C, THF), 33.33 (s, 1C,
CH2SiMe3), 36.64 (s, 1C, NCH3), 71.90 (s, 2C, THF),
111.91 (s, 2C, o-NC6H4P), 114.86 (s, 2C, p-NC6H4P),
129.05 (br, 8C, m-P(C6H5)2), 129.51 (s, 4C, p-P(C6H5)2),
134.06 (br, 8C, o-P(C6H5)2), 135.50 (br, 4C, ipso-
P(C6H5)2), 136.17 (s, 2C, o-PC6H4N), 165.60 (d,
2JC–P = 23 Hz, 2C, ipso-NC6H4P). 31P{1H} NMR (C6D6,
161.90 MHz) d À4.27. IR (KBr pellets): m 3689(w),
3380(w), 3054(s), 2950(s), 2891(s), 2856(s), 2784(s),
1963(w), 1896(w), 1817(w), 1775(w), 1588(s), 1459(s),
1437(s), 1414(s), 1312(s), 1300(s), 1247(m), 1168(w),
1126(m), 1094(w), 1069(w), 1037(m), 1027(m), 998(w),
914(w), 857(s), 746(s), 723(s), 694(s) cmÀ1. Anal. Calc.
for C46H53N2OP2SiLu (914.93): C, 60.39; H, 5.84; N,
3.06. Found: C, 59.95; H, 5.74; N, 2.88%.
4.3.1. Syntheses of (2-diphenylphosphinophenyl)-N-
(benzyl) aniline (HL2)
At À78 ꢁC under stirring, a THF solution (40 mL) of
the compound (2-diphenylphosphino)aniline (2.77 g, 10.00
mmol) was added nBuLi dropwise (6.56 mL, 10.00 mmol)
and reacted for 1h, then, benzyl chloride (1.21 mL,
10.00 mmol) was syringed into the system. After main-
tained for 2 h at À78 ꢁC, the reaction mixture was warmed
to room temperature gradually and kept stirring overnight.
Volatiles were removed off under reduced pressure and
degassed water (10 mL) was added. The resultant mixture
was extracted with deoxygenated dichloromethane
(20 · 3 mL). The organic phase was separated, dried over
degassed MgSO4, and filtered. Removal of dichlorometh-
ane afforded residue, which was recrystallized from
CH2Cl2/CH3CH2OH at À30 ꢁC for several days to give
white solid of HL2 (3.32 g, 90%). 1H NMR (400 MHz,
DMSO-d6, 25 ꢁC): d 4.35 (d, JH–H = 6 Hz, 2H, CH2),
5.74 (m, 1H, NH), 6.51–6.54 (m, 2H, o-PC6H4N,
p-NC6H4P), 6.62–6.65 (m, 1H, o-NC6H4P), 7.01–7.19 (m,
4H, o,p-CH2C6H5, p-PC6H4N), 7.21–7.28 (m, 6H,
m-CH2C6H5, o-P(C6H5)2), 7.40–7.42 (m, 6H, m,
p-P(C6H5)2). 13C NMR (100 MHz, DMSO-d6, 25 ꢁC): d
46.46 (s, 1C, CH2), 110.53 (s, 1C, p-NC6H4P), 116.59
4.3.3. Synthesis of [2-(C6H5CH2N)-C6H4 P(Ph)2]2LuCH2
SiMe3(THF) (2)
To a hexane solution (2.0 mL) of Lu(CH2SiMe3)3THF2
(0.175 g, 0.301 mmol), 1 equiv of HL2 (0.128 g, 0.301 mmol
in 4 mL toluene) was dropwise added at room temperature.
The mixture was stirred for 3 h, then concentrated and
added 3 mL hexane. The mixture was cooled to À30 ꢁC
and kept overnight to afford pale yellow solid, which was
washed with small amount of hexane to remove off impuri-
ties and then dried in vacuum to give complex 2 in 75% yield
(0.120 g). The crystal grew from a solution of toluene/hex-
1
(s, 1C, p-NC6H4P), 118.25 (d, 1C, JC–P = 9 Hz, ipso-
PC6H4N), 126.55 (s, 1C, p-CH2C6H5), 126.68 (s, 2C,
o-CH2C6H5), 128.19 (s, 2C, m-CH2C6H5), 128.66 (d,
3JC–P = 6 Hz, 4C, m-P(C6H5)2), 128.85 (s, 2C,
1
ane (1:3 vol/vol) at À30 ꢁC within a couple of days. H
2
p-P(C6H5)2), 130.34 (s, 1C, p-PC6H4N), 133.24 (d, JC–P
NMR (400 MHz, C6D6, 25 ꢁC): d À0.55 (s, 2H, CH2SiMe3),
0.24 (s, 9H, SiMe3), 1.24 (br, 8H, THF), 3.81(br, 8H, THF),
5.10 (br, 2H, CH2C6H5), 6.51 (t, 4H, o,p-NC6H4P), 6.99 (t,
JH–H = 8 Hz, 2H, m-NC6H4P), 7.13–7.32(m, 32H,
P(C6H5)2, CH2C6H5, o,m-PC6H4N), 7.43 (br, 8H,
o-P(C6H5)2). 13C NMR (100 MHz, C6D6, 25 ꢁC): d 4.88 (s,
9C, SiMe3), 25.86 (s, 2C, THF), 37.76 (s, 1C, CH2SiMe3),
48.04 (s, 2C, CH2Ph), 71.36 (s, 2C, THF), 114.69 (s, 2C,
o-NC6H4P), 115.46 (s, 2C, p-NC6H4P), 126.40 (s, 4C,
= 19 Hz, 4C, o-P(C6H5)2), 133.65 (s, 1C, o-PC6H4N),
1
135.32 (d, JC–P = 9 Hz, 2C,), 139.66 (s, 1C, ipso-
CH2C6H5), 150.42 (d, 1C, ipso-NC6H4P). IR (KBr pellets):
m 3396(m), 3045(m), 3028(m), 2861(m), 1961(w), 1897(w),
1824(w), 1771(w), 1581(s), 1567(s), 1497(s), 1475(s),
1433(s), 1357(m), 1321(s), 1298(s), 1289(s), 1254(m),
1232(w), 1177(m), 1165(m), 1131(w), 1089(m), 1069(m),
1042(w), 1025(m), 999(w), 913(w), 840(m), 807(m),
797(m), 745(s), 697(s). Anal. Calc. for C25H22NP: C,
81.72; H, 6.04; N, 3.81. Found: C, 81.68; H, 6.10; N, 3.79%.
3
p-CH2C6H5), 128.01 (s, 4C, o-CH2C6H5), 129.26 (d, JC–P
= 7 Hz, 8C, m-P(C6H5)2), 129.82 (s, 4C, p-P(C6H5)2),
2
133.50 (s, 2C, p-PC6H4N), 134.29 (d, JC–P = 12 Hz, 8C,
4.3.2. Synthesis of [2-(CH3N)-
C6H4P(Ph)2]2Lu(CH2SiMe3)(THF) (1)
o-P(C6H5)2), 135.48 (s, 4C, o-CH2C6H), 142.08 (s, 2C,
ipso-CH2C6H5), 163.86 (s, 2C, ipso-NC6H4P). 31P{1H}
NMR (C6D6, 161.90 MHz) d À0.94. IR (KBr pellets): m
3395(w), 3054(m), 2999(w), 2947(m), 2889(w), 2817(w),
2794(w), 1959(w), 1895(w), 1811(w), 1771(w), 1576(s),
1544(m), 1493(s), 1479(m), 1457(s), 1434(s), 1353(m),
1313(s), 1290(s), 1269(s), 1249(m), 1236(m), 1165(s),
1134(m), 1093(m), 1069(w), 1039(s), 1026(s), 1000(w),
884(s), 852(s), 818(s), 747(s), 731(s), 696(s) cmÀ1. Anal.
Calc. for C58H61N2OP2SiLu (1067.09): C, 65.28; H, 5.76;
N, 2.63. Found: C, 64.87; H, 5.33; N, 2.18%.
To a hexane solution (2.0 mL) of Lu(CH2SiMe3)3THF2
(0.175 g, 0.301 mmol), 1 equiv of HL1 (0.087 g, 0.301 mmol
in 4 mL toluene) was dropwise added at room temperature
and reacted for 3 h. After concentrated, the solution was
added small amount of hexane and then cooled to
À30 ꢁC. Pale yellow solid was isolated overnight, which
was washed with hexane (1 mL) carefully to remove off
impurities and dried in vacuum to afford pale yellow pow-
ders of 1 in 63% yield (0.086 g). 1H NMR (400 MHz, C6D6,
25 ꢁC): d À0.45 (s, 2H, CH2SiMe3), 0.38 (s, 9H, SiMe3),
1.09 (br, 4H, THF), 3.19 (br, 6H, ArMe), 3.74 (br, 4H,
THF), 6.58 (t, JH–H = 7.2 Hz, 2H, p-NC6H4P), 6.65
(br, 2H, o-NC6H4P), 7.02–7.24 (m, 18H, o-PC6H4N,
4.3.4. Synthesis of [2-(C6H5CH2N)-C6H4P(Ph)2]3Lu (3)
To a hexane solution (2.0 mL) of Lu(CH2SiMe3)3THF2
(0.175 g, 0.301 mmol), 1 equiv of HL2 (0.128 g, 0.301 mmol

4950
S. Li et al. / Journal of Organometallic Chemistry 692 (2007) 4943–4952
in 4 mL toluene) was dropwise added at room temperature.
The mixture was then stirred for 24 h. Removal of the vol-
atiles gave a deep red solid, which was dissolved with 2 mL
toluene and kept at room temperature for 5 days to give
colorless crystalline complex 3 (0.087 g, 68%). IR (KBr
pellets): m 3388(w), 3054(w), 3028(w), 2863(w), 1955(w),
1586(s), 1572(s), 1501(s), 1478(w), 1446(s), 1434(s), 1360
(w), 1316(m), 1288(m), 1164(m), 1137(w), 1092(w),
1070(w), 1041(w), 1027(m), 999(w), 901(w), 845(w), 816
(w), 745(s), 696(s) cmÀ1. Anal. Calc. for C75H63N3P3Lu
(1274.21): C, 70.69; H, 4.98; N, 3.30. Found: C, 70.11; H,
4.31; N, 2.91%.
temperature. The mixture was then stirred for 4 h.
Removal of the volatiles gave a yellow residue which was
added toluene and hexane and kept at À30 ꢁC for 1 day
to afford crystals of complex 4b in 89% yield (0.270 g).
1H NMR (400 MHz, C6D6, 25 ꢁC): d 0.45–0.31 (22H,
CH2SiMe3). 1.23 (br, 4H, THF), 2.33 (s, 6H, ArMe), 3.56
(br, 4H, THF), 6.05 (t, JH–H = 6 Hz, 1H, o-NC6H4P),
6.60 (t, JH–H = 7.6, 1H, p-NC6H4P), 7.09 (t, JH–
H = 6.8 Hz, 1H, p-NC6H3Me2), 7.06–7.11 (dt, 3H,
m-NC6H3Me2, p-PC6H4N), 7.17 (tt, 2H, p-P(C6H5)2),
7.24–7.31 (m, 4H, m-PC6H5, o-PC6H4N), 7.91–7.95 (dd,
JH–H = 8.4 Hz, 4H, o-PC6H5). 13C NMR (100 MHz,
C6D6, 25 ꢁC): d 4.52 (s, 6C, SiMe3),19.78 (s, 2C, ArMe),
25.40 (s, 4C, THF), 46.62 (s, 2C, CH2SiMe3), 71.87 (s,
4.3.5. Synthesis of [2-(2,6-Me2C6H3N)-
C6H4P(Ph)2]Y(CH2SiMe3)2 (THF)2 (4a)
3
4C, THF), 112.88 (s, JC–P = 6 Hz, 1C, o-NC6H4P),
In a NMR sample tube, a solution of Y(CH2Si-
Me3)3THF2 (0.02 g, 0.04 mmol) in C6D6 (0.6 mL) was
added equimolar HL3 (0.015 g, 0.04 mmol). The obtained
solution was transferred to a NMR sample tube and the
116.97 (s, 1C, p-NC6H4P), 125.14 (s, 1C, p-NC6H3Me2),
129.26 (s, JC–P = 7 Hz, 4C, m-P(C6H5)2), 129.52 (s, 2C,
3
o-NC6H3Me2), 130.08 (s, 2C, p-P(C6H5)2), 133.87 (s, 1C,
2
p-PC6H4N), 134.43 (d, JP–C = 12 Hz, 4C, o-P(C6H5)2),
1
1
reaction was monitored by H NMR technique at different
134.74 (d, JC–P = 18 Hz, 2C, ipso-P(C6H5)2), 136.92 (s,
reaction time. The molar ratio of complexes was calculated
on the relative integral intensity to TMS. After 20 min,
HL3 was completely consumed and after 6 h, the signal
of CH2SiMe3 and CH2SiMe3 nearly disappeared. 1H
1C, o-PC6H4N), 137.90 (s, 2C, m-NC6H3Me2), 147.85 (s,
1C, ipso-NC6H3Me2), 161.87 (d, JC–P = 26 Hz, 1C, ipso-
1
NC6H4P). 31P{1H} NMR (C6D6, 161.90 MHz) d À14.91.
IR (KBr pellets): m 3363(m), 3052(m), 2953(m), 1955(w),
1584(s), 1569(s), 1489(s), 1435(s), 1377(w), 1302(s),
1281(w), 1248(m), 1207(w), 1181(w), 1160(m), 1125(w),
1094(m), 1068(w), 1027(m), 999(w), 917(w), 861(s), 746(s),
697(s) cmÀ1. Anal. Calc. for C44H67NOPSi2Sc (758.11):
C, 69.71; H, 8.91; N, 1.85. Found: C, 69.24; H, 8.77; N,
1.72%.
NMR (400 MHz, C6D6, 25 ꢁC):
d
À0.21 (s, 4H,
CH2SiMe3), 0.08 (s, SiMe4), 0.30 (s, 18H, SiMe3), 1.37 (s,
16H, THF), 2.29 (s, 6H, ArMe), 3.73 (s, 16H, THF), 6.01
(d, JH–H = 7.2 Hz, 1H, o-NC6H4P), 6.54 (t, JH–H
= 7.2 Hz, 1H, p-NC6H4P), 6.94 (t, JH–H = 7.2 Hz, 1H, p-
NC6H3), 7.04–7.07 (dt, 3H, m-NC6H3Me2, p-PC6H4N),
7.15 (tt, JH–H = 7.2 Hz, 2H, p-P(C6H5)2), 7.20–7.24 (m,
5H, o-PC6H4N, m-P(C6H5)2), 7.79–7.83 (dd, 4H, o-P-
(C6H5)2). 13C NMR (100 MHz, C6D6, 25 ꢁC): d 0.34 (s,
SiMe4), 4.77,4.97 (s, SiMe3), 19.61 (s, 2C, ArMe), 25.60
(s, 8C, THF), 34.06 (d,JY–C = 35.3 Hz, Y(CH2SiMe3)3),
40.54 (d, 2C, JY–C = 29.1 Hz, CH2SiMe3), 70.14 (s, 8C,
THF), 112.95 (s, 1C, o-NC6H4P), 116.04 (s, 1C,
p-NC6H4P), 125.19 (s, 1C, p-NC6H3Me2), 129.19 (d,
3JC–P = 7.8 Hz, 4C, m-P(C6H5)2), 129.71 (s, 2C, m-NC6-
H3Me2), 129.95 (s, 2C, p-P(C6H5)2), 133.59 (s, 1C,
4.3.7. Synthesis of [2-(2,6-Me2C6H3N)-
C6H4P(Ph)2]Lu(CH2SiMe3)2 (THF) (4c)
To a hexane solution (2.0 mL) of Lu(CH2SiMe3)3THF2
(0.235 g,
0.405 mmol),
equivalent
HL3
(0.153 g,
0.405 mmol) in 4 mL toluene was dropwise added at room
temperature. The mixture was then stirred for 4 h.
Removal of the volatiles gave a yellow residue which was
added toluene and hexane and kept at À30 ꢁC for 1 day
to afford crystals of complex 4c in 72% yield (0.259 g).
1H NMR (600 MHz, C6D6, 25 ꢁC): d À0.34 (br, 4H,
CH2SiMe3), 0.31 (s, 18H, SiMe3), 1.14 (s, 4H, THF),
2.34 (s, 6H, ArMe), 3.38 (s, 4H, THF), 6.06 (d,
JH–H = 7.2 Hz, 1H, o-NC6H4P), 6.55 (t, JH–H = 7.2 Hz,
1H, p-NC6H4P), 6.96 (t, JH–H = 7.2 Hz, 1H, p-NC6H3),
7.08 (dt, JH–H = 7.2 Hz, 3H, m-NC6H3Me2, p-PC6H4N),
7.16 (tt, JH–H = 7.2 Hz, 2H, p-P(C6H5)2), 7.21 (t, 1H,
o-PC6H4N), 7.22–7.25 (m, 4H, m-P(C6H5)2), 7.87 (dd,
JH–H = 8.4 Hz, 4H, o-P(C6H5)2). 13C NMR (150 MHz,
C6D6, 25 ꢁC): d 4.55 (s, 6C, SiMe3),19.20 (s, 2C, ArMe),
24.86 (s, 4C, THF), 46.73 (d, 2C, JLu–C = 10.5 Hz,
2
p-PC6H4N), 133.31 (d, JC–P = 13.7 Hz, 4C, o-P(C6H5)2),
134.11 (s, 2C, ipso-P(C6H5)2), 136.58 (s, 1C, o-PC6H4N),
138.64 (s, 2C, ipso-Me2C6H3), 145.35 (s, 1C, ipso-
NC6H3Me2), 161.73 (s, 1C, ipso-NC6H4P). 31P{1H}
NMR (C6D6, 161.90 MHz) d À12.99. IR (KBr pellets): m
3361(m), 3050(m), 2951(m), 1959(w), 1584(s), 1566(s),
1485(s), 1434(s), 1378(w), 1303(s), 1284(w), 1247(m),
1205(w), 1183(w), 1160(m), 1125(w), 1095(m), 1066(w),
1026(m), 999(w), 918(w), 861(s), 748(s), 695(s) cmÀ1. Anal.
Calc. for C48H75NO2PSi2Y (873.06): C, 66.03; H, 8.66; N,
1.60. Found: C, 65.56; H, 8.43; N, 1.54%.
3
CH2SiMe3), 70.75 (s, 4C, THF), 113.12 (s, JC–P = 6 Hz,
4.3.6. Synthesis of [2-(2,6-Me2C6H3N)-
C6H4P(Ph)2]Sc(CH2SiMe3)2 (THF) (4b)
To a hexane solution (2.0 mL) of Sc(CH2SiMe3)3THF2
1C, o-NC6H4P), 115.81 (s,3JC–P = 4.5 Hz, 1C, p-NC6H4P),
124.58 (s, 1C, p-NC6H3Me2), 128.29 (s, 1C, ipso-PC6H4N),
3
128.83 (d, JC–P = 7.5 Hz, 4C, m-P(C6H5)2), 129.17 (s, 2C,
(0.180 g,
0.400 mmol),
equivalent
HL3
(0.152 g,
m-NC6H3Me2), 129.67 (s, 2C, p-P(C6H5)2), 133.48 (s, 1C,
2
0.400 mmol) in 4 mL toluene was dropwise added at room
p-PC6H4N), 133.98 (d, JC–P = 13.5 Hz, 4C, o-P(C6H5)2),

S. Li et al. / Journal of Organometallic Chemistry 692 (2007) 4943–4952
4951
134.11 (s, 2C, ipso-P(C6H5)2), 136.45 (s, 1C, o-PC6H4N),
137.87 (s, 2C, ipso-Me2C6H3), 146.30 (s, 1C, ipso-
NC6H3Me2), 162.31 (d, JC–P = 24.2 Hz, 1C, ipso-
addition of ethanol (100 mL). The polymer product was
collected by filtration, washed with ethanol, and then dried
in vacuo at 60 ꢁC to a constant weight.
1
NC6H4P). 31P{1H} NMR (C6D6, 161.90 MHz) d À7.99.
IR (KBr pellets): m 3363(m), 3053(m), 2954(s), 2872(w),
1584(s), 1489(s), 1435(s), 1377(w), 1300(s), 1272(w),
1248(s), 1208(w), 1184(w), 1160(w), 1122(w), 1094(m),
1068(w), 1037(m), 1000(w), 860(s), 768(w), 746(s), 696(s)
cmÀ1. Anal. Calc. for C44H67NOPSi2Lu (888.12): C,
59.50; H, 7.60; N, 1.58. Found: C, 58.89; H, 7.34; N, 1.45%.
Acknowledgements
The authors are grateful for financial supports from Jilin
Provincial Science and Technology Bureau for project No.
20050555; The National Natural Science Foundation of
China for Projects Nos. 20571072 and 20674081; The Min-
istry of Science and Technology of China for Project No.
2005CB623802; ‘‘Hundred Talent Scientist Program’’ of
Chinese Academy of Sciences.
4.3.8. Synthesis of [2-(2,6-Me2C6H3N)-
C6H4P(Ph)2]Yb(CH2SiMe3)2(THF) (4d)
To a hexane solution (2.0 mL) of Yb(CH2SiMe3)3THF2
(0.232 g,
0.400 mmol),
equivalent
HL3
(0.153 g,
Appendix A. Supplementary material
0.400 mmol) in 4 mL toluene was dropwise added at room
temperature. The mixture was then stirred for 4 h.
Removal of the volatiles gave a deep red residue which
was added toluene and hexane and kept at À30 ꢁC for
2 days to afford crystals of complex 4d in 86% yield
(0.304 g). IR (KBr pellets): m 3361(w), 3053(m), 2950(s),
2857(s), 1906(w),1580(s), 1544(m), 1533(w), 1481(w),
1458(s), 1429(s), 1377(m), 1295(s), 1270(s), 1249(w),
1236(m), 1186(s), 1160(m), 1130(s), 1092(m), 1068(m),
1037(s), 1010(s), 876(w), 853(s), 766(w), 750(s), 712(w),
695(s) cmÀ1. Anal. Calc. for C44H67NOPSi2Yb (886.39):
C, 59.63; H, 7.62; N, 1.58. Found: C, 58.11; H, 7.56; N,
1.49%.
CCDC 635731, 622504, 627390, 614088, 628755 and
607919 contain the supplementary crystallographic data
for 2, 3, 4b, 4c, 4d and 4e. These data can be obtained free
of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/
j.jorganchem.2007.07.022.
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