Chiral diamine bis(phenolate) TiIV and ZrIV complexes-synthesis, structures and reactivity

Article abstract of DOI:10.1002/ejic.201100470

Neutral and cationic titanium and zirconium diamine bis(phenolate) complexes supported by chiral ligands L¹ and L² are described [L¹ = (R)-6,6′-{1-(dimethylamino)propan-2- ylazanediyl}bis(methylene)-bis(2,4-di-tert-butylphenolate);L² = (S)-6,6′-{(1-ethylpyrrolidin-2-yl)methylazanediyl}bis(methylene)-bis(2, 4-di-tert-butylphenolate)]. Complexes[TiL(OiPr)₂] [L = L¹ (1), L² (2)], [TiL²X(OiPr)] [X = Cl (3), CH₂Ph (4)], [TiL¹(CH₂Ph)₂] (5), [ZrLCl₂] [L = L¹ (6), L² (7)] and [ZrL(CH₂Ph) ₂] [L = L¹ (8), L² (9)] are C ₁-symmetric species readily prepared in moderate to high yields. Cationic compounds were obtained from complexes 5, 8 and 9 through reactions with B(C₆F₅)₃. The monocationic species reveal the I·²-binding character of the benzyl groups and noncoordinated [B(C₆F₅)₃(CH₂Ph)] ^-. Complexes 5-9 were tested in the polymerization of ethylene and propylene upon activation with modified methylaluminoxane (MMAO), B(C ₆F₅)₃ or [NHMe₂Ph]⁺ as cocatalysts. The [ZrL¹Cl₂]/MMAO and [ZrL ¹(CH₂Ph)₂]/B(C₆F₅) ₃ systems revealed high activities in the polymerization of propylene (2.1 A- 10³ and 1.5 A- 10³ g_pol mmol_cat^-1 h^-1, respectively), leading to atatic polypropylene, whereas the titanium complexes showed no activity.

Full text of DOI:10.1002/ejic.201100470

FULL PAPER
DOI: 10.1002/ejic.201100470
Chiral Diamine Bis(phenolate) TiIV and ZrIV Complexes – Synthesis,
Structures and Reactivity
Sónia Barroso,[a] Pedro Adão,[a] M. Teresa Duarte,[a] Auke Meetsma,[b]
João Costa Pessoa,[a] Marco W. Bouwkamp,[b] and Ana M. Martins*[a]
Keywords: Titanium / Zirconium / Chiral ligands / Polymerization
Neutral and cationic titanium and zirconium diamine bis-
(phenolate) complexes supported by chiral ligands L1 and L2
through reactions with B(C6F5)3. The monocationic species
reveal the η2-binding character of the benzyl groups and
noncoordinated [B(C6F5)3(CH2Ph)]–. Complexes 5–9 were
tested in the polymerization of ethylene and propylene upon
activation with modified methylaluminoxane (MMAO),
B(C6F5)3 or [NHMe2Ph]+ as cocatalysts. The [ZrL1Cl2]/
MMAO and [ZrL1(CH2Ph)2]/B(C6F5)3 systems revealed high
activities in the polymerization of propylene (2.1ϫ103 and
1.5ϫ103 gpol mmolcat–1 h–1, respectively), leading to atatic
polypropylene, whereas the titanium complexes showed no
activity.
are described [L1
=
(R)-6,6Ј-{1-(dimethylamino)propan-
2-ylazanediyl}bis(methylene)-bis(2,4-di-tert-butylphenolate);
L2
(S)-6,6Ј-{(1-ethylpyrrolidin-2-yl)methylazanediyl}bis-
(methylene)-bis(2,4-di-tert-butylphenolate)]. Complexes
=
[TiL(OiPr)2] [L = L1 (1), L2 (2)], [TiL2X(OiPr)] [X = Cl (3),
CH2Ph (4)], [TiL1(CH2Ph)2] (5), [ZrLCl2] [L = L1 (6), L2 (7)]
and [ZrL(CH2Ph)2] [L = L1 (8), L2 (9)] are C1-symmetric spe-
cies readily prepared in moderate to high yields. Cationic
compounds were obtained from complexes 5, 8 and 9
with B(C6F5)3, [TiLCl(CH2Ph)2] (Figure 1) was found to be
highly active in 1-hexene polymerization giving the highest
molecular weight poly(1-hexene) ever prepared at room
temperature.[3h] In addition, the presence of an extra donor
on the sidearm proved to be crucial for the stabilization of
active catalytic species and it has been found to suppress
chain transfer reactions.[3a,3b] Dibenzyltitanium and zirco-
nium diamine bis(phenolate) complexes [MLtBu(CH2Ph)2]
(M = Ti, Zr, Figure 1), featuring a nitrogen donor on a
sidearm, led to exceptionally high activities in the polymeri-
zation of 1-hexene and, in the case of titanium, to living
polymerization.[3a,3b] The diamine bis(phenolate) zirconium
complex [ZrLtBu(CH2Ph)2] and its dichloride analogue
Introduction
There has been a growing interest in the development
of postmetallocene single-site transition metal catalysts for
alkene polymerization in order to achieve control over the
stereochemistry and molecular weight of the polymers.[1] In
recent years, group 4 transition metal complexes supported
by chelating ligands containing nitrogen and/or oxygen co-
ordinating sites have received considerable attention as
active catalysts for olefin polymerization.[1,2] Aryloxide li-
gands are particularly attractive since they form strong
metal–oxygen bonds with electropositive group 4 metals,
which are expected to stabilize the resulting complexes.
Group 4 amine bis(phenolate) metal complexes are effec-
tive catalysts for 1-hexene,[3] 4-methylpentene,[4] vinylcyclo-
hexane[4] and propylene polymerization,[5] and for ethylene/
1-hexene copolymerization.[6] Evaluation of structural
modifications in the activity of titanium and zirconium di-
amine bis(phenolate) catalysts has shown the importance
of the bulkiness and electronic properties of the phenolate
substituents in 1-hexene polymerization. When activated
[a] Centro de Química Estrutural, Instituto Superior Técnico,
Universidade Técnica de Lisboa,
Av. Rovisco Pais, 1049-001 Lisboa, Portugal
E-mail: ana.martins@ist.utl.pt
[b] Molecular Inorganic Chemistry Group, Stratingh Institute for
Chemistry, University of Groningen,
Nijenborgh 4, 9747 AG Groningen, The Netherlands
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201100470.
Figure 1. Diamine bis(phenolate) TiIV and ZrIV complexes active
in α-olefin polymerization.
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A. M. Martins et al.
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[ZrLtBuCl2] (Figure 1) were found to be active propylene L2(OiPr)2] (2) were obtained as yellow crystalline solids, in
polymerization catalysts, upon activation with MAO, lead- good yields, by treating the ligand precursors H2L1 and
ing to high molecular weight, atactic polypropylene.[5]
H2L2, respectively, with Ti(OiPr)4 in a 1:1 ratio. The com-
In view of these results, chiral derivatives of titanium and pounds are stable to hydrolysis and do not show any sign
1
zirconium diamine bis(phenolate) complexes could be good of decomposition after several days in air. The H NMR
candidates for the stereoselective polymerization of α-ole- spectra of 1 and 2 feature two different isopropoxide groups
fins. In fact, Kol and coworkers have recently reported a and distinct resonances for the aromatic and aliphatic pro-
variety of chiral dianionic ligands of the type [N2O2] and tons of the ancillary ligands pointing to rigid C1-symmetric
their corresponding zirconium and titanium complexes for chelates on the NMR time scale.
the stereoselective polymerization of α-olefins.[7] However,
the only example of a chiral tripodal diamine bis(phenolate)
complex reported to date is a molybdenum compound and
no catalytic applications have been described.[8]
As part of our research with diamine bis(phenolate) com-
plexes of group 3, 4 and 5 metals[9] we undertook the prepa-
ration of chiral tripodal diamine bis(phenol) ligand precur-
sors. Attempts to introduce chirality in the benzylic methyl-
ene protons were hampered by the formation of 1,3-benz-
oxazines.[10] In view of these results we decided to adopt a
different strategy and introduce chirality in the carbon
chain of the ethylenediamine sidearm (H2L1 in Figure 2).[9b]
Herein we describe a new chiral diamine bis(phenolate) li-
Scheme 1. Synthesis of titanium complexes.
gand precursor displaying a ethylpyrrolidine moiety in the
sidearm (H2L2 in Figure 2) together with neutral and cat-
ionic titanium and zirconium complexes supported by these
two chiral ligands. The results obtained with these com-
plexes as ethylene and propylene polymerization catalysts
are also included.
The chirality of 1 and 2 was further confirmed by the CD
spectra of THF solutions of both compounds (Figure 3).
Although the diamine sidearm moiety is different in the two
complexes, the CD spectra of 1 and 2 show that the bands
in the range close to 280 nm are nearly mirror images of
each other.[12] This is probably due to the similarity between
the skeletons of L1 and L2 and the opposite configurations
of their chiral carbon atoms (R in L1 and S in L2). More-
over, the CD spectrum of 2 is more intense than that of 1,
which may be related to the existence of an extra source of
chirality upon coordination of the ethylpyrrolidine hetero-
cycle of L2.[13]
Figure 2. Chiral diamine bis(phenol) ligand precursors employed
in this work.
Results and Discussion
Synthesis and Characterization of the Ligands and Neutral
Complexes
Chiral ligand precursor H2L2 (Figure 2), was prepared
by a single-step Mannich condensation reaction of a substi-
tuted phenol, formaldehyde and an optically pure diamine,
(S)-(1-ethylpyrrolidin-2-yl)methanamine, following re-
Figure 3. CD spectra of 1 and 2 in THF.
1
ported procedures.[11] The H NMR spectrum of H2L2 dis-
plays only two sets of resonances for the tert-butyl groups
The reaction of M–OR groups with Me3SiCl is a known
and for the aromatic protons. However, the resonances as- procedure for the replacement of alkoxide by chloride li-
signed to the diamine moiety and the benzylic protons are gands as a result of the formation of strong silicon–oxygen
consistent with a C1-symmetric compound. Thus, the benz- bonds.[3a,3d] Aiming to prepare [TiL2Cl2], 2 was treated with
ylic protons are diastereotopic, appearing as an AB system 2 equiv. of Me3SiCl in dichloromethane. The NMR spec-
and all the resonances assigned to the diamine moiety are trum of the crude product revealed a complex mixture. Nev-
nonequivalent.
ertheless, crystals of [TiL2Cl(OiPr)] (3) suitable for X-ray
Scheme 1 shows the reactions performed to prepare the diffraction were obtained by recrystallization of the mixture
new chiral titanium complexes. [TiL1(OiPr)2] (1) and [Ti- from toluene.
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Chiral Diamine Bis(phenolate) TiIV and ZrIV Complexes
Sequential addition of Me3SiCl and PhCH2MgCl to a result either from trans/cis-phenolate coordination or from
solution of 2 led to [TiL2(OiPr)(CH2Ph)] (4), which was iso- diastereomers associated with the chirality of the N2 nitro-
lated in 70% yield. The NMR spectrum of 4 is consistent gen upon bonding to the zirconium, as shown in Figure 4.
with a C1-symmetric species. The two benzylic methylene Isomers of trans/cis-phenolate coordination have been re-
protons of L2 appear as two AX systems giving rise to four ported for [ZrLtBuCl2], which also has a diamine bis(phen-
doublets [δ = 3.85 and 2.84 ppm (2JHH = 14.5 Hz); δ = 3.78 olate) donor set bearing a pyridine donor on the side-
and 3.10 ppm (2JHH = 13.4 Hz)], whereas the methylene arm.[14b] However, if trans/cis-phenolate coordination is as-
protons of the benzyl ligand appear as one AB system [δ = sumed for 7, three different types of isomers would be ex-
3.01 and 3.92 ppm (2JHH = 8.7 Hz)]. A NOESY experiment pected, as shown in Scheme 3. If the two possible configu-
pointed out a spatial correlation between the isopropoxide rations, R/S, resulting from the coordination of N2 are also
group and the ortho-tBu groups attesting its coordination considered, six diastereoisomers might be expected. The
1
trans to the tripodal nitrogen. In addition, the NOESY two isomers observed in the H NMR spectrum of 7 are
spectrum shows spatial correlations between one of the or- tentatively assigned to trans-phenolate species with S and R
tho-tBu groups and the protons of the methyl group of the configuration at N2 in accordance with the geometry ob-
ethylpyrrolidine moiety attesting for its static coordination served for compounds 1–6.
to the metal on the NMR time scale. As a result the epi-
merization of this chiral centre in solution is blocked.
The reaction of 1 with Me3SiCl followed by the addition
of Mg(CH2Ph)2(THF)2 led, upon recrystallization from
cold pentane, to the isolation of the dibenzyl complex
1
[TiL1(CH2Ph)2] (5). The H NMR spectrum of 5 indicates
the formation of a rigid C1-symmetric species. The benzylic
methylene protons of L1 are observed as two AB systems,
whereas the methylene protons of the benzyl ligands appear
as two AX systems. The NMR spectrum is comparable to
that previously published for the nonchiral analogue of 5,
[TiLtBu(CH2Ph)2].[3a,3d] Complex 5 is thermally unstable in
solution at room temperature but can be kept in the solid
state at –37 °C for several weeks. All attempts to obtain
crystals of 5 suitable for X-ray diffraction were unsuccess-
ful.
Scheme 2. Synthesis of zirconium complexes.
The reactions performed for the preparation of the new
chiral zirconium complexes are shown in Scheme 2. Upon
protonolysis of Zr(CH2SiMe3)2Cl2(Et2O)2 with the neutral
ligand precursors H2L1 and H2L2 in THF, SiMe4 elimi-
nation was observed affording [ZrL1Cl2] (6) and [ZrL2Cl2]
(7) in 48 and 16% isolated yield, respectively. The low yields
obtained in these reactions are surprising since this pro-
cedure is a known entry to the chemistry of zirconium sup-
ported by a variety of ligands.[14] In view of this, an alterna-
tive method, consisting of the formation of [ZrL1(NMe)2]
and [ZrL2(NMe)2] intermediates, was attempted. Thus, the
reactions of H2L1 and H2L2 with Zr(NMe2)4 followed by
in situ addition of excess Me3SiCl led to the isolation of
complexes 6 and 7 in 68 and 57% yield, respectively, as light
yellow solids. The 1H NMR spectrum of 6 is consistent with
a C1-symmetric species displaying two AX spin systems for
the benzylic methylene protons of the ligand. The coordina-
tion of the NMe2 moiety was confirmed by a NOESY ex-
Figure 4. Possible isomers of 7.
Scheme 3.
1
periment. The H NMR spectrum of 7 is consistent with
the presence of two isomers of C1 symmetry. The NOESY
The chirality of 6 and 7 was further confirmed by the
experiment has shown that there is no dynamic exchange CD spectra of THF solutions of the complexes (Figure 5).
between them. Although many resonances of the minor No bands are observed in the visible region of the CD spec-
species are overlapped by the resonances of the major one, tra due to the absence of charge transfer bands in that re-
the AX spin systems are appreciably different due to the gion, also reflected in the light colour of the complexes
benzylic methylene protons, which is possibly related to ring (pale yellow). As observed for 1 and 2, the CD spectrum of
current effects caused by different locations of these nuclei 6 is more intense than that of 7, due to the additional chiral
in relation to the phenolate rings. The two isomers might centre.[15]
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A. M. Martins et al.
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bulk of the amine sidearm of L2 and the presence of β-H
atoms in the ethylpyrrolidine moiety that may provide β-H
elimination as an accessible decomposition pathway.
Scheme 4. Generation of the cationic species.
Figure 5. CD spectra of 6 and 7 in THF.
1
The new complexes were characterised by H, 13C and
19F NMR spectra as monocationic species with a noncoor-
dinated [PhCH2B(C6F5)3]– anion.[15] The 1H and 13C NMR
spectra of 10, 11 and 12 are consistent with C1-symmetric
species resembling their neutral precursors. The resonances
corresponding to the MCH2Ph methylene protons show up
as broad singlets in the H NMR spectra of the three com-
plexes indicating that the rotation of the benzyl group is
constrained.
Compounds [ZrL1(CH2Ph)2] (8) and [ZrL2(CH2Ph)2] (9)
were obtained by single-step metathesis reactions between
tetrabenzylzirconium and the ligand precursors. Surpris-
1
ingly, according to H NMR spectroscopic data, only one
1
isomer was obtained for 9, suggesting that formation of two
isomers observed for 7 is blocked by the steric bulk of the
benzyl group. This assumption was confirmed by the reac-
tion of 7 (mixture of isomers) with 2 equiv. of PhCH2MgCl
that led to the formation of one isomer of 9 in 59% isolated
Relevant chemical shifts for the neutral precursors 5, 8
and 9 and the corresponding cationic species 10, 11 and 12
are listed in Table 1. The assessment of the benzyl coordina-
tion mode by NMR is often obscured by fluxional pro-
cesses. However, in static systems η2-benzyl ligands in cat-
ionic species are usually characterized by downfield-shifted
methylene proton resonances and highfield shifts for the
ipso and the methylene carbon signals when compared to
the neutral precursors. A high 1JCH for the methylene group
(Ͼ 130 Hz) is also an indication of η2-benzyl coordina-
tion.[17] The upfield shift (Ͼ 29 ppm) of the TiCH2Ph car-
bon resonance in the 13C NMR spectrum of 10, the high
1JCH value for ZrCH2Ph (139 Hz) and the upfield shift of
the ipso carbon in the 13C NMR spectrum of 11 and the
upfield shift of the ipso carbon resonance in the 13C NMR
spectrum of 12 are suggestive of η2-benzyl coordination to
the metal. Although no downfield shift of methylene proton
resonances was observed for the cationic species, it is im-
portant to mention that these experiments were run at room
temperature and that fluxional processes occurring in these
conditions may obscure the identification of all criteria. The
broad resonances due to the benzyl methylene protons are
1
yield. The H and 13C NMR spectra of 8 and 9 are consis-
tent with C1-symmetric species. The two dibenzyl com-
plexes show characteristic AB systems for the dia-
stereotopic methylene protons of the benzyl ligands in their
1H NMR spectra (δ = 2.55–2.96 ppm). In the 13C NMR
spectra the ZrCH2Ph methylene group is found in the range
1
δ = 66–70 ppm with small JCH (112–124 Hz). The latter
value and the observation of downfield resonances for the
ipso-carbons suggest η1-coordination of the benzyl li-
gands.[15] For both complexes, the NOESY spectra show
spatial correlations that confirm the coordination of the
ethylpyrrolidine and dimethylamine nitrogen atoms to the
metal centre and trans configuration of the phenolate
groups. The tripodal ligand forces the two benzyl ligands to
be mutually cis.
Generation and Characterization of Cationic Species
The reactions of tris(pentafluorophenyl)borane with 5, 8
and 9 proceed rapidly and quantitatively at room tempera-
ture in [D5]bromobenzene, through the abstraction of one
benzyl group and formation of the corresponding cationic
species as shown in Scheme 4. In solution, [ZrL1(CH2Ph)2]-
[PhCH2B(C6F5)3] (11) is stable for several days at room
temperature, whereas [TiL1(CH2Ph)2][PhCH2B(C6F5)3] (10)
decomposes gradually at room temperature over one or two
days and is only stable at –35 °C. [ZrL2(CH2Ph)2]-
[PhCH2B(C6F5)3] (12) is unstable and decomposes over a
couple of hours even at low temperatures. The high instabil-
ity of the titanium vs. the zirconium complexes follows the
trend observed for first row metal organometallic com-
pounds and is related to weaker metal–ligand bonds.[16] The
lower stability of 12 is likely associated with the high steric
Table 1. Selected 1H and 13C NMR spectroscopic data for com-
pounds 5 and 8–12.
1H NMR (δ, ppm)
MCH2 [2JHH, Hz]
13C NMR (δ, ppm)
MCH2Ph [1JCH, Hz] Cipso MCH2Ph
5
3.56 and 3.34 [8.4];
3.26 and 2.79 [9.5]
98.6,
85.1
55.6
68.6 [123],
66.6 [121]
72.6 [139]
69.1 [124],
68.3 [112]
68.8
155.2,
148.2
147.4
150.2,
148.0
131.6
148.9,
148.6
135.8
10 3.25, br.
2.79 and 2.67;
2.67 and 2.55 [9.8]
11 2.94, br.
2.96 and 2.79;
2.86 and 2.79
12 2.55, br.
8
9
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Chiral Diamine Bis(phenolate) TiIV and ZrIV Complexes
an indication that equilibrium between two η2-benzyl iso-
Complex 8, activated with B(C6F5)3 and in the presence
mers takes place in solution as shown in Scheme 3.
of the scavenger tri(isobutyl)aluminoxane (TIBAO), gave
The reaction of 8 with [PhNMe2H][B(C6F5)4] in [D5]bro- the highest activities for the polymerization of ethylene and
mobenzene leads to [ZrL2(CH2Ph)][B(C6F5)4] (13) with the propylene. These reactions are highly exothermic and are
1
release of toluene and PhNMe2 (Scheme 4). The H and accompanied by heating of the mixture. Complex 9 was in-
13C NMR spectra of 13 indicate a cationic species similar active in the same conditions, which is possibly related to
to 11, and the 19F NMR spectrum confirms the presence the instability of 12 discussed above. Complex 8 led to poly-
of the [B(C6F5)4]– anion.
propylene (PP) with a polymodal distribution and low mo-
lecular weight (7.4ϫ103 gmol–1), contrasting with its non-
chiral analogue [ZrLtBu(CH2Ph)2], which was found to be
active in the polymerization of propylene, upon activation
with MAO, yielding PP with a high molecular weight (Mw
Catalytic Studies – Ethylene and Propylene Polymerization
The chiral titanium and zirconium complexes were
screened for their potential application as catalyst precur-
sors in ethylene and propylene polymerization and the re-
sults are presented in Table 2. The activities are based on
the observed productivity over the 30 min run time extrapo-
lated to 1 h and they do not take into account possible dif-
ferences in activity profiles for the various catalysts over the
run time. These values are to be used as relative measures
of catalyst efficiency rather than absolute activities. All
polymers obtained were analysed by high-temperature gel
permeation chromatography (HT-GPC).
=
3.6ϫ105 gmol–1) and
a
narrow PDI of 1.8.[5]
[ZrLtBu(CH2Ph)2] was also shown to be highly reactive in
the polymerization of 1-hexene.[5] Therefore, the perform-
ance of 8 was also tested in the polymerization of 1-hexene
but it showed no activity.
The mixture of 5 and B(C6F5)3 was found to be inactive
in the polymerization of ethylene and propylene, even in
the presence of a scavenger. This result contrasts with those
published for the nonchiral analogue of 5, [TiLtBu
-
(CH2Ph)2], which was found to lead to living polymeriza-
tion of 1-hexene.[3a]
Upon activation with MMAO, 6 and 7 exhibit low activi-
ties[18] in the polymerization of ethylene. Molecular weight
To investigate the influence of the cocatalyst,
analysis of the resulting polymers show narrow polydisper- [PhNMe2H][B(C6F5)4] was also used to activate 8 in the
sity (PDI = 1.4) for the polyethylene (PE) obtained from presence of TIBAO. Under these conditions, the activity of
6, whereas a very wide PDI was obtained with 7. In the 8 was lower for the polymerization of ethylene and higher
polymerization of propylene, 6 was found to be highly for the polymerization of propylene in comparison to the
active, with an activity of 2.1ϫ103 gpolmmolcat–1h–1, activities obtained using [B(C6F5)3]. However, these small
whereas 7 was inactive.
differences were not significant.
Table 2. Data for ethylene, propylene and 1-hexene polymerization.[a]
Precatalyst Activator (equiv.) Scavenger (equiv.)
Ethylene polymerization[c]
mpol [g]
Activity[b]
Mw [gmol–1] Mn [gmol–1]
PDI (Mw/Mn)
6
7
8
9
5
8
9
8
MMAO (200)
MMAO (200)
B(C6F5)3 (1)
B(C6F5)3 (1)
B(C6F5)3 (1)
B(C6F5)3 (1)
B(C6F5)3 (1)
[NHMe2Ph]
[B(C6F5)4] (1)
0.090
0.017
traces
traces
traces
1.395
traces
0.993
4ϫ101
7
1.1ϫ103
6.9ϫ105
8.1ϫ102
2.9ϫ103
1.4
240.9
TIBAO (20)
TIBAO (20)
TIBAO (20)
TIBAO (20)
5.6ϫ102
3.8ϫ102
2.1ϫ104
3.7ϫ104
5.4ϫ103
1.1ϫ104
3.8
3.4
Propylene polymerization[c]
6
7
8
9
5
8
9
8
MMAO (200)
MMAO (200)
B(C6F5)3 (1)
B(C6F5)3 (1)
B(C6F5)3 (1)
B(C6F5)3 (1)
B(C6F5)3 (1)
[NHMe2Ph]
[B(C6F5)4] (1)
5.314
traces
traces
traces
traces
3.665
traces
7.454
2.1ϫ103
7.5ϫ103
2.1ϫ103
3.6
TIBAO (20)
TIBAO (20)
TIBAO (20)
TIBAO (20)
1.5ϫ103
3.0ϫ103
7.4ϫ103
8.0ϫ103
1.3ϫ103
1.2ϫ103
5.8
6.5
1-Hexene polymerization[d]
6
8
MMAO (200)
B(C6F5)3 (1)
1.343
n.d.
5.4ϫ102
4.5ϫ103
2.1ϫ103
2.2
[a] Precatalyst: 5 μmol; t = 30 min. [b] gpol mmolcat–1 h–1. [c] Monomer pressure: 5 bar. [d] Monomer: 9 mL (6.06 g).
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Despite the chirality of the catalyst precursors no
enantioselectivity was achieved since all PP samples ob-
tained were atactic according to 13C NMR spectra.
Aiming to obtain information about the catalytic reac-
tions, one equivalent of ethylene was added, at ambient
temperature, to a NMR tube containing a [D5]bromobenz-
1
ene solution of 11. Upon stirring for a few minutes, the H
NMR spectrum indicates the presence of 11 and a new C1-
symmetric species that seems to present an interaction be-
tween the zirconium and ethylene. Indeed, ethylene reso-
nances in the mixture appear as one singlet at δ = 5.13 ppm
1
in the H NMR spectrum and give rise to a signal at δ =
75.7 in the 13C NMR spectrum (1H δ = 5.29 ppm, 13C δ =
123.9 ppm for free ethylene).[19] After 24 h stirring no sig-
1
nificant changes were observed in the H NMR spectrum.
Figure 7. ORTEP diagram of H2L2, 40% probability level ellip-
Upon addition of excess ethylene (+5 equiv.) the solution
becomes slightly turbid and broadening of the NMR sig-
nals is observed. The resonances assigned to 11 disappear,
indicating that its conversion to new compound(s) is com-
plete. The NMR spectroscopic data did not allow further
conclusions but indicate that 11 interacts with ethylene in
solution.
soids. Hydrogen atoms are omitted for clarity.
positions are occupied by the tripodal nitrogen N1 and by
O3 of the isopropoxide ligand. The titanium atom is slightly
displaced from the equatorial plane [0.24(1) Å], in the direc-
tion of the isopropoxide ligand. The phenolate groups dis-
play trans configuration, folding towards the chloride li-
gand with a narrow dihedral angle of 121(1)° between the
planes containing the phenolate rings, reflecting the bulki-
ness of the heterocyclic amine. The pyrrolidine cycle is coor-
dinated to the metal through the nitrogen atom N2. Chiral
atoms N2 and C2 have S configuration, and the five-mem-
bered metallacycle is defined by Ti1–N1–C1–C2–N2, which
displays δ conformation. The least square plane containing
the pyrrolidine ring defines a dihedral angle of 72.6(6)° with
the equatorial plane and dihedral angles of 24.2(7) and
64.1(8)° with the planes containing the phenolate rings
(planes that include C11 and C21, respectively). The rela-
tively short Ti1–O3 bond length [1.79(1) Å] is consistent
with a pronounced π-donation from the isopropoxide oxy-
gen atom to the metal. This effect is commonly observed in
titanium(IV) alkoxy derivatives[20] and is more pronounced
for this type of ligand than for the phenoxide groups, which
display Ti–O bond lengths of 1.89(1) Å.
Single-Crystal X-ray Diffraction Studies
Suitable crystals for X-ray diffraction were obtained for
H2L1, H2L2, 3, 6 and 8.
H2L1 crystallizes in the orthorhombic system, space
group Pbca, with two symmetry-independent molecules in
the asymmetric unit as depicted in Figure 6. H2L2 crys-
tallizes in the monoclinic system, space group P21 with four
symmetry-independent molecules in the asymmetric unit as
depicted in Figure 7. The configurations adopted by both
compounds in the solid state are determined by O–H···N
and O–H···O intramolecular hydrogen bond interactions.
Selected structural parameters for H2L1 and H2L2 and a
more detailed description are given in the Supporting Infor-
mation.
Figure 6. ORTEP diagram of H2L1, 40% probability level ellip-
soids. Hydrogen atoms are omitted for clarity.
An ORTEP diagram of the molecular structure of 3 is
shown in Figure 8 and selected structural parameters are
listed in Table 3. The compound crystallizes in the triclinic
system, space group P1, with one molecule of 3 and one
toluene solvate molecule in the asymmetric unit. The tita-
nium centre displays a distorted octahedral geometry with
the equatorial plane defined by atoms O1, O2 and N2 of
Figure 8. ORTEP diagram of 3, 40% probability level ellipsoids.
the diamine bis(phenolate) ligand and Cl1, and the axial Hydrogen atoms are omitted for clarity.
4282 Eur. J. Inorg. Chem. 2011, 4277–4290
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Chiral Diamine Bis(phenolate) TiIV and ZrIV Complexes
Table 3. Selected structural parameters for 3, 6 and 8.[a]
3
6
8
3
6
8
Distances [Å]
M(1)–O(1)
M(1)–O(2)
M(1)–N(1)
M(1)–N(2)
1.89(1)
1.89(1)
2.31(1)
2.32(1)
1.979(5)
1.978(6)
2.393(7)
2.437(7)
0.239(2)
1.996(1)
1.989(2)
2.453(2)
2.610(2)
0.209(2)
M(1)–X(1)
M(1)–X(2)
M(1)–C(72)
M(1)–C(82)
1.79(1)
2.37(0)
2.422(2)
2.441(3)
2.310(2)
2.345(2)
3.002(2)
3.314(2)
M(1)–equat. plane[b] 0.244(2)
Angles [°]
O(1)–M(1)–O(2)
O(1)M(1)–N(1)
O(1)–M(1)–X(1)
O(1)–M(1)–N(2)
O(1)–M(1)–X(2)
O(2)–M(1)–N(1)
O(2)–M(1)–X(1)
X(1)–M(1)–N(2)
M(1)–O(1)–C(11)
M(1)–O(2)–C(21)
161.4(4)
83.8(4)
98.8(4)
91.2(4)
87.9(3)
79.1(4)
99.6(4)
88.5(4)
130.7(7)
135.3(8)
160.8(2)
80.8(2)
98.6(2)
87.4(2)
92.3(2)
80.0(2)
99.6(2)
86.3(2)
145.2(5)
146.9(5)
160.5(1)
80.8(1)
98.8(1)
85.9(1)
93.2(1)
79.7(1)
98.2(1)
80.1(1)
145.3(1)
145.7(1)
O(2)–M(1)–N(2)
O(2)–M(1)–X(2)
N(1)–M(1)–X(1)
N(1)–M(1)–N(2)
N(1)–M(1)–X(2)
X(1)–M(1)–X(2)
N(2)–M(1)–X(2)
M(1)–C(71)–C(72)
M(1)–C(81)–C(82)
θ[c]
91.5(4)
86.4(3)
164.1(4)
75.7(4)
95.0(3)
100.8(3)
170.7(3)
87.8(2)
99.6(2)
160.7(2)
74.5(2)
99.4(2)
99.9(1)
173.8(2)
87.7(1)
91.7(1)
149.9(1)
69.8(1)
105.8(1)
104.3(1)
175.6(1)
102.5(1)
118.4(1)
152.7(1)
120.7(7)
157.2(3)
[a] M = Ti in 3 and Zr in 6 and 8; X(1) = O(3) in 3, Cl(1) in 6 and C(71) in 8; X(2) = Cl(1) in 3, Cl(2) in 6 and C(81) in 8. [b] The
equatorial plane is defined by atoms O(1), O(2), N(2) and X(2). [c] θ is the dihedral angle between the planes containing the phenolate
rings.
The molecular structure of complex 6 is depicted in Fig-
The molecular structure of 8 is depicted in Figure 10 and
ure 9 and selected structural parameters are listed in selected structural parameters are listed in Table 3. The
Table 3. The compound crystallizes from toluene in the mo- compound crystallizes from toluene in the monoclinic sys-
noclinic system, space group P21/c, with one molecule in tem, space group P21/c, with one molecule of 8 and one
the asymmetric unit. Compound 6 displays distorted octa- toluene solvate molecule in the asymmetric unit. The geom-
hedral geometry with the equatorial plane defined by atoms etry around the zirconium centre is again distorted octahe-
O1, O2, N2 and Cl2, and the axial positions occupied by dral with the equatorial plane defined by atoms O1, O2 and
the tripodal nitrogen N1 and Cl1. The zirconium atom is N2 of L1 and C81 of one of the benzyl ligands, whereas the
slightly away from the equatorial plane [0.227(3) Å] in the axial positions are occupied by the tripodal nitrogen N1
direction of Cl1. The overall structural parameters of 6 are and C71 of the other benzyl ligand. The phenolate groups
comparable to the nonchiral analogue [ZrLtBuCl2].[5] The are mutually trans, in accordance with the discussion of the
structure presents the phenolate groups in trans configura- NMR results, and bend towards the dimethylamine sidearm
tion, bending towards the sidearm with a dihedral angle of defining a dihedral angle of 152.7(1)°. The zirconium atom
157.2(3)° between the planes containing the phenolate rings. is slightly away from the equatorial plane [0.209(2) Å] in the
Despite the formal absence of a mirror plane in the mole- direction of the benzyl ligand. The NMe2 moiety is weakly
cule, the overall ligand core remains quasisymmetrical be- bonded to the metal as indicated by the long Zr1–N2 bond
cause the C2 chain of the diamine moiety is twisted to ac-
commodate the extra methyl group away from the phenol-
ate groups, thus nearly bisecting the angle between them.
Figure 9. ORTEP diagram of 6, 40% probability level ellipsoids.
Hydrogen atoms and a disordered carbon atom are omitted for
clarity.
Figure 10. ORTEP diagram of 8, 40% probability level ellipsoids.
Hydrogen atoms and a disordered carbon atom are omitted for
clarity.
Eur. J. Inorg. Chem. 2011, 4277–4290
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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4283

A. M. Martins et al.
FULL PAPER
length of 2.610(2) Å. In general the structure of 8 resembles of the chloride ions by benzyl groups leads to a unique ste-
that of 6. The longer Zr–N bond lengths in 8 may be attrib- reoisomer, possibly due to steric constraints.
uted to a richer metal centre and higher steric bulk caused
Compounds 5, 8 and 9 were used as precursors for cat-
by the benzyl ligands.
ionic complexes formed upon removal of one benzyl ligand.
There is a noticeable difference in the bonding mode of The NMR spectra of these species are indicative of η2-
the two benzyl ligands in the structure of 8. The narrower benzyl coordination. Assessment of the catalytic properties
Zr1–C71–C72 angle [102.5(1) vs. 118.4(1)°], as well as the of the compounds revealed high activities in the polymeri-
shorter Zr1–C72 distance [3.002(2) vs. 3.314(2) Å] observed zation of propylene [2126 and 1466 gpol mmolcat–1h–1 for
in one benzyl group (Figure 10), point to partial η2-binding [ZrL1Cl2]/MMAO and [ZrL1(CH2Ph)2]/B(C6F5)3 systems,
to the Zr.[3c,17]
respectively] yielding atactic polypropylene. Conversely, the
As shown in Figure 11 the arrangement around the trip- titanium complexes showed very low activities in the poly-
odal nitrogen N1 in 3 is helical, whereas the structures of 6 merization of ethylene and propylene.
and 8 present a nearly symmetric arrangement of the
phenolates that bend towards the sidearm.
Experimental Section
General: All preparations and subsequent manipulations of air/
moisture sensitive compounds were performed under a nitrogen at-
mosphere using standard Schlenk line and glovebox techniques.
Reagents were purchased from commercial suppliers. H2L1,
Zr(CH2Ph)4,B(C6F5)3,Zr(CH2SiMe3)2Cl2(Et2O)2andMg(CH2Ph)2-
(THF)2 were prepared according to literature procedures.[9b,16,21]
Solvents (THF, toluene, pentane) were dried by percolation under
a nitrogen atmosphere through columns of alumina, molecular si-
eves, and supported copper oxygen scavenger (BASF R3-11) or by
distillation with Na/K alloy (THF, hexane, Et2O, [D8]THF, C6D6).
C6D5Br and CH2Cl2 were dried with CaH2 and distilled under re-
duced pressure. [D8]Toluene and CD2Cl2 were dried with molecular
sieves (4 Å) and degassed by the freeze-pump-thaw method. NMR
spectra were recorded with Varian Inova 500, Varian Gemini VXR
Figure 11. Wireframe diagrams of 3, 6 and 8 viewed along the N1–
400, Varian VXR 300 and Bruker Advance II+ 300 and 400 MHz
M axis (M = Ti in 3, Zr in 6 and 8). Groups in trans position
(UltraShield Magnet) NMR instruments. 1H and 13C chemical
relative to the tripodal nitrogen (OiPr in 3, Cl1 in 6 and CH2Ph in
8) and the tert-butyl groups are omitted for clarity.
shifts (δ) are expressed in ppm relative to Me4Si, whereas 19F nu-
cleus was referenced to an external reference capillary with
CF3COOH.
The centrosymmetric space groups obtained for the
structures of H2L1, 6 and 8 indicate that the resolution of
the racemic diamine for the preparation of ligand precursor
H2L1 was not efficient.
Synthetic Procedures
H2L2: The diamine used to prepare H2L2, (S)-(1-ethylpyrrolidin-2-
yl)methanamine, was obtained optically active pure from commer-
cial suppliers.
A solution of 2,4-di-tert-butylphenol (4.13 g,
20.00 mmol), (S)-(–)-2-aminomethyl-1-ethylpyrrolidine (1.35 mL,
12.30 mmol) and 36% aqueous formaldehyde (1.65 mL,
22.00 mmol) in methanol (10 mL) was stirred at room temperature
for 3 d. The mixture was cooled to –20 °C overnight leading to
the formation of a sticky precipitate. The supernatant solution was
decanted and the solid was redissolved in MeOH. Upon cooling,
the compound precipitated out of solution. The solid was separated
by filtration and washed thoroughly with ice cold methanol to give
an off-white solid in 30% yield. The compound was further purified
Conclusions
New chiral neutral and cationic diamine bis(phenolate)
complexes were prepared and characterized. With the ex-
ception of [TiL(OiPr)2] [L = L1 (1), L2 (2)], the titanium
compounds are, in general, less stable than the zirconium
analogues. The compounds derived from L1 are closely re-
lated to their nonchiral analogues concerning their struc-
tures and properties. The presence of the methyl group α to
by recrystallization from methanol. 1H NMR (300 MHz, CDCl3,
4
the tripodal nitrogen atom does not impose a significant 25 °C): δ = 9.69 (br., 2 H, OH), 7.20 (d, JHH = 2.2 Hz, 2 H, CH-
Ar), 6.87 (d, 4JHH = 2.2 Hz, 2 H, CH-Ar), 3.87 (d, 2JHH = 13.3 Hz,
change in the complex structures because the torsion of the
sidearm C2 chain releases the steric bulk that results from
2
2 H, ArCH2N), 3.43 (d, JHH = 13.2 Hz, 2 H, ArCH2N), 3.35 (m,
1 H, CH2), 3.04 (m, 1 H, CH2CH3), 2.66 (m, 2 H, CH2, CH), 2.48
(m, 1 H, NCH2), 2.25 (m, 2 H, CH2CH3, CH2), 1.90 (m, 1 H,
the presence of the substituent. In general, the compounds
supported by L2 are less stable than those bearing L1. This
CH2), 1.68 (m, 2 H, CH2), 1.48 (m, 1 H, CH2), 1.39 [s, 18 H,
feature is related to the high steric bulk imposed by the
3
C(CH3)3], 1.27 [s, 18 H, C(CH3)3], 1.20 (t, JHH = 7.2 Hz, 3 H,
ethylpyrrolidine moiety and to the presence of β-H atoms,
which may provide an extra decomposition pathway.
Furthermore, the presence of two chiral centres [C(S) and
CH2CH3) ppm. 13C{1H} NMR (75 MHz, CDCl3, 25 °C): δ =
153.6, 140.1, 136.0 and 121.8 (Cipso-Ar), 124.9 and 123.3 (CH-Ar),
64.4 (CH), 58.5 (ArCH2N), 54.0 (CH2), 53.6 (CH2), 50.0
(CH2CH3), 34.9 and 34.1 [C(CH3)3], 31.7 and 29.6 [C(CH3)3], 28.5
N
(R/S)] upon coordination of L2 gives rise to the formation
of one pair of diastereomers for [ZrL2Cl2] (7). Replacement (CH2), 22.8 (CH2), 13.0 (CH2CH3) ppm. C37H60N2O2·0.1(CH3OH)
4284
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Eur. J. Inorg. Chem. 2011, 4277–4290

Chiral Diamine Bis(phenolate) TiIV and ZrIV Complexes
(567.66): calcd. C 78.44, H 10.72, N 4.93; found C 78.36, H 11.21,
N 4.94.
revealed a complex mixture of compounds. Orange crystals of 3
were obtained from a toluene solution of the mixture at –37 °C.
The small amount of crystals obtained prevented further charac-
terization.
[TiL1(OiPr)2] (1): A solution of H2L1 (323 mg, 0.6 mmol) in Et2O
was slowly added to a 1 m solution of Ti(OiPr)4 in Et2O (0.6 mL,
0.6 mmol) in the same solvent. The solution was stirred for 2 h at
room temperature. Evaporation of all the volatiles under reduced
pressure led to a yellow solid in 62% yield. 1H NMR (300 MHz,
[TiL2(OiPr)(CH2Ph)] (4): A 1 m solution of Si(Me)3Cl in CH2Cl2
(0.42 mL, 0.42 mmol) was added to a solution of 2 (153.1 mg,
0.21 mmol) in CH2Cl2 and the mixture was stirred for 2 h at room
temperature. All the volatiles were removed under reduced pressure.
The residue was redissolved in Et2O and a 1 m solution of
PhCH2MgCl in Et2O (0.42 mL, 0.42 mmol) was added and the
mixture was further stirred for 2 h at room temperature. The solu-
tion was filtered and the solvent was evaporated under reduced
pressure to give a red solid in 70% yield. 1H NMR (300 MHz,
C6D6, 25 °C): δ = 7.64 (s, 1 H, p-CH-Ar), 7.59 (s, 1 H, p-CH-Ar),
7.09 (s, 1 H, o-CH-Ar), 6.96 (m, 2 H, CH2Ph), 6.92 (s, 1 H, o-CH-
4
C6D6, 25 °C): δ = 7.58 (d, JHH = 2.5 Hz, 1 H, p-CH-Ar), 7.56 (d,
4JHH = 2.5 Hz, 1 H, p-CH-Ar), 7.07 (d, 4JHH = 2.4 Hz, 1 H, o-CH-
4
3
Ar), 7.04 (d, JHH = 2.5 Hz, 1 H, o-CH-Ar), 5.25 [sept, JHH
=
3
6.1 Hz, 1 H, CH(CH3)2], 4.75 [sept, JHH = 6.1 Hz, 1 H, CH-
(CH3)2], 4.66 (d, JHH = 13.8 Hz, 1 H, NCH2Ar), 3.51 (d, JHH
2
2
=
2
13.2 Hz, 1 H, NCH2Ar), 3.39 (d, JHH = 13.2 Hz, 1 H, NCH2Ar),
3.29 (d, 2JHH = 13.9 Hz, 1 H, NCH2Ar), 3.19 [m, 1 H, NCH(CH3)-
CH2N], 2.47 [t, 1 H, NCH(CH3)CH2N], 2.34 [s, 3 H, N(CH3)2],
2.04 [s, 3 H, N(CH3)2], 1.79 [s, 9 H, C(CH3)3], 1.76 [s, 9 H,
C(CH3)3], 1.53 [d, JHH = 6.1 Hz, 3 H, CH(CH3)2], 1.50 [d, JHH
= 6.1 Hz, 3 H, CH(CH3)2], 1.44 [s, 9 H, C(CH3)3], 1.41 [s, 9 H,
C(CH3)3], 1.12 [m, 1 H, NCH(CH3)CH2N], 0.99 [d, 3JHH = 6.1 Hz,
3
3
Ar), 6.83 (d, JHH = 7.7 Hz, 2 H, CH2Ph), 6.75 (t, JHH = 7.2 Hz,
3
3
3
1 H, CH2Ph), 5.14 [sept, JHH = 6.0 Hz, 1 H, CH(CH3)2], 3.85 (d,
2JHH = 14.5 Hz, 1 H, NCH2Ar), 3.78 (d, JHH = 13.4 Hz, 1 H,
2
2
2
NCH2Ar), 3.10 (d, JHH = 13.4 Hz, 1 H, NCH2Ar), 3.01 (d, JHH
= 8.7 Hz, 1 H, CH2Ph), 2.92 (d, JHH = 8.7 Hz, 1 H, CH2Ph), 2.84
(d, JHH = 14.5 Hz, 1 H, NCH2Ar), 2.74 (m, 1 H, CH2), 2.70 (m,
2
3
3 H, CH(CH3)2], 0.88 [d, JHH = 6.1 Hz, 3 H, CH(CH3)2], 0.59
2
[d, JHH = 6.7 Hz, 3 H, NCH(CH3)CH2N] ppm. 13C{1H} NMR
3
1 H, CH2), 2.60 (m, 1 H, NCH2CH), 2.58 (m, 1 H, CH2CH3), 2.23
(m, 1 H, CH2), 1.98 (m, 1 H, CH2CH3), 1.86 [s, 9 H, C(CH3)3],
1.82 [s, 9 H, C(CH3)3], 1.51 [m, 7 H, CH2, CH(CH3)2], 1.43 [s, 9
H, C(CH3)3], 1.39 [s, 9 H, C(CH3)3], 1.14 (m, 1 H, CH2), 0.85 (m,
(75 MHz, C6D6, 25 °C): δ = 163.4, 160.1, 139.5, 139.2, 136.2, 134.7,
125.9 and 124.4 (Cipso-Ar), 124.7 and 124.3 (CH-Ar), 77.9 and 77.8
[CH(CH3)2], 64.6 [NCH(CH3)CH2N], 62.1 and 57.3 (NCH2Ar),
53.0 [NCH(CH3)CH2N], 51.3 and 50.1 [N(CH3)2], 36.1, 35.9 and
34.7 [C(CH3)3], 32.5, 32.4, 31.5 and 31.4 [C(CH3)3], 27.6, 27.5,
26.7 and 26.5 [CH(CH3)2], 8.7 [NCH(CH3)CH2N] ppm.
C41H70N2O4Ti·3.5(C3H8O) (912.61): calcd. C 67.73, H 10.82, N
3.07; found C 67.79, H 11.04, N 2.84.
3
2 H, CH2), 0.62 (t, JHH = 7.1 Hz, 3 H, CH2CH3), 0.30 (m, 1 H,
CH2) ppm. 13C{1H} NMR (75 MHz, C6D6, 25 °C): δ = 161.5,
159.4, 152.1, 141.2, 140.7, 136.7, 135.6 and 129.7 (Cipso-Ar), 128.7,
127.9 and 127.3 (CH-Ph), 127.0 and 125.9 (Cipso-Ph), 124.9, 124.8,
124.2 and 123.9 (CH-Ar), 121.5 (CH-Ph), 79.8 [CH(CH3)2], 76.1
(CH2Ph), 65.5 and 65.1 (NCH2Ar), 63.5 (NCH2CH), 62.5, 50.8
and 50.1 (CH2), 36.3, 36.2 and 34.8 [C(CH3)3], 32.5, 32.4, 31.8 and
31.3 [C(CH3)3], 27.3 (CH2), 26.8 and 26.5 [CH(CH3)2], 22.6 (CH2),
11.7 (CH2CH3) ppm. C48H75N2O3Ti·1.7(CH2Cl2) (919.80): calcd.
C 64.82, H 8.58, N 3.04; found C 64.85, H 8.48, N 3.04.
[TiL2(OiPr)2] (2): A solution of H2L2 (339 mg, 0.6 mmol) in Et2O
was slowly added to a 1 m solution of Ti(OiPr)4 in Et2O (0.6 mL,
0.6 mmol) in the same solvent. The solution was stirred for 2 h at
room temperature. Evaporation of all the volatiles under reduced
1
pressure led to a yellow solid in 64% yield. H NMR (400 MHz,
4
C6D6, 25 °C): δ = 7.58 (d, JHH = 2.4 Hz, 1 H, p-CH-Ar), 7.51 (d,
[TiL1(CH2Ph)2] (5): A 1 m solution of Si(Me)3Cl in CH2Cl2
(6.00 mL, 6.00 mmol) was added to a solution of 2 (1.76 g,
2.50 mmol) in CH2Cl2 and the mixture was further stirred for 2 h
at room temperature. The solvent was evaporated to dryness and
the residue was redissolved in THF and treated with a solution of
Mg(CH2Ph)2(THF)2 (0.88 g, 2.50 mmol) in THF. The mixture was
stirred at room temperature for 4 h and then evaporated to dryness
leading to a residue that was extracted in pentane. After filtration
the solution was cooled to –54 °C leading to a microcrystalline
dark red solid in 41% yield that was separated by filtration and
dried in vacuo. 1H NMR (500 MHz, C6D6, 25 °C): δ = 7.89 (d,
4JHH = 2.3 Hz, 1 H, p-CH-Ar), 7.18 (d, 4JHH = 2.5 Hz, 1 H, o-CH-
4
3
Ar), 6.69 (d, JHH = 2.2 Hz, 1 H, o-CH-Ar), 5.14 [sept, JHH
=
2
6.1 Hz, 1 H, CH(CH3)2], 4.90 (d, JHH = 14.4 Hz, 1 H, NCH2Ar),
4.29 [sept, JHH = 6.1 Hz, 1 H, CH(CH3)2], 4.10 (m, 1 H, CH2),
3.89 (d, JHH = 12.3 Hz, 1 H, NCH2Ar), 3.29 (m, 2 H, CH2CH3),
3.19 (d, JHH = 14.6 Hz, 1 H, NCH2Ar), 2.96 (m, 1 H, NCH2CH),
2.86 (t, JHH = 12.4 Hz, 1 H, CH2), 2.69 (d, JHH = 12.4 Hz, 1 H,
NCH2Ar), 2.63 (m, 1 H, CH2), 1.79 [s, 9 H, C(CH3)3], 1.77 [s, 9 H,
C(CH3)3], 1.51 [d, JHH = 3.8 Hz, 3 H, CH(CH3)2], 1.49 [d, JHH
= 3.8 Hz, 3 H, CH(CH3)2], 1.47 [s, 9 H, C(CH3)3], 1.44 (m, 2 H,
CH2), 1.38 (m, 1 H, CH2), 1.34 [s, 9 H, C(CH3)3], 1.20 (m, 1 H,
3
2
2
2
2
3
3
4
3JHH = 7.4 Hz, 2 H, CH2Ph), 7.74 (d, JHH = 2.1 Hz, 1 H, CH-
3
3
NCH2CH), 0.92 (t, JHH = 7.2 Hz, 3 H, CH2CH3), 0.72 [d, JHH
4
3
Ar), 7.70 (d, JHH = 2.1 Hz, 1 H, CH-Ar), 7.41 (t, JHH = 7.6 Hz,
3
= 6.1 Hz, 3 H, CH(CH3)2], 0.55 (m, 1 H, NCH2CH), 0.48 [d, JHH
4
2 H, CH2Ph), 7.00 (m, 4 H, CH-Ar, CH2Ph), 6.90 (d, JHH
2.1 Hz, 1 H, CH-Ar), 6.60 (t, JHH = 7.5 Hz, 2 H, CH2Ph), 6.48
(t, JHH = 7.2 Hz, 1 H, CH2Ph), 3.56 (d, JHH = 8.4 Hz, 1 H,
=
= 6.1 Hz, 3 H, CH(CH3)2] ppm. 13C{1H} NMR (101 MHz, C6D6,
3
25 °C): δ = 164.4, 159.7, 139.6, 139.2, 136.6, 134.5 and 125.0 (Cipso
-
3
2
Ar), 124.3, 124.1 and 124.0 (CH-Ar), 123.5 (Cipso-Ar), 123.0 (CH-
Ar), 78.0 and 77.9 [CH(CH3)2], 63.6 (NCH2Ar), 62.9 (NCH2CH),
61.8 (NCH2Ar), 61.1, 54.7 and 53.4 (CH2), 36.1, 35.8, 34.7 and
34.6 [C(CH3)3], 32.6, 32.4, 31.3 and 31.3 [C(CH3)3], 29.2 (CH2),
27.3, 27.2, 26.2 and 25.8 [CH(CH3)2], 25.2 (CH2), 11.0 (CH2CH3)
ppm. C43H72N2O4Ti·2.5(C3H8O) (878.56): calcd. C 68.99, H 10.55,
N 3.19; found C 68.66, H 10.26, N 3.19.
2
2
CH2Ph), 3.34 (d, JHH = 8.4 Hz, 1 H, CH2Ph), 3.26 (d, JHH
=
9.5 Hz, 1 H, CH2Ph), 2.98 (d, 2JHH = 14.1 Hz, 1 H, ArCH2N), 2.79
2
2
(m, JHH = 8.9 Hz, 2 H, CH2Ph, ArCH2N), 2.63 (d, JHH
=
14.1 Hz, 1 H, ArCH2N), 2.52 [m, 1 H, NCH(CH3)CH2N], 2.39 (d,
2JHH = 14.0 Hz, 1 H, ArCH2N), 2.19 [s, 18 H, C(CH3)3], 2.05 [m,
1 H, NCH(CH3)CH2N], 1.85 [s, 3 H, N(CH3)2], 1.82 [s, 3 H,
N(CH3)2], 1.36 [s, 9 H, C(CH3)3], 1.35 [s, 9 H, C(CH3)3], 0.53 [m,
3
[TiL2Cl(OiPr)] (3): A 1 m solution of Si(Me)3Cl in CH2Cl2
(5.00 mL, 5.00 mmol) was added to a solution of 2 (1.82 g,
2.50 mmol) in CH2Cl2 and the mixture was stirred for 2 h at room
temperature. All the volatiles were removed under reduced pressure
to give an orange solid. Analysis of the NMR spectroscopic data
1 H, NCH(CH3)CH2N], 0.51 [d, JHH = 6.5 Hz, 3 H, NCH(CH3)-
CH2N] ppm. 13C-{1H}NMR (126 MHz, C6D6, 25 °C): δ = 161.1
and 160.1 (Cipso-Ar), 155.2 and 148.2 (Cipso-Ph), 141.6, 141.2, 136.1
and 135.3 (Cipso-Ar), 128.8 and 128.6 (CH2Ph), 128.5 and 127.0
(Cipso-Ar), 126.9, 126.7 and 126.2 (CH2Ph), 124.7, 124.4, 124.3 and
Eur. J. Inorg. Chem. 2011, 4277–4290
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4285

A. M. Martins et al.
FULL PAPER
124.0 (CH-Ar), 122.0 and 121.9 (CH2Ph), 98.6 and 85.1 (CH2Ph),
CH2), 0.70 (m, 3 H, CH2, CH2CH3), 0.21 (m, 1 H, CH2) ppm. 13C-
65.7 [NCH(CH3)CH2N], 61.0 and 56.8 (ArCH2N), 50.6 {1H}NMR (101 MHz, C6D6, 25 °C): δ = 156.3, 142.7, 142.4, 138.0,
[NCH(CH3)CH2N], 37.9, 36.0, 35.8 and 34.2 [C(CH3)3], 31.8, 31.7
and 31.3 [C(CH3)3], 31.2 [N(CH3)2], 31.1 [C(CH3)3], 30.8 [N-
136.9 and 126.9 (Cipso-Ar), 125.8, 125.2, 125.1 and 124.5 (CH-Ar),
66.2 (CH), 65.7 and 65.2 (ArCH2N), 59.4, 52.0 and 51.5 (CH2),
(CH3)2], 7.5 [NCH(CH3)CH2N] ppm. C49H70N2O2Ti·0.5(C4H8O) 36.1, 35.9, 34.9 and 34.8 [C(CH3)3], 32.3, 32.2, 31.5, 31.0
(802.44): calcd. C 76.28, H 9.29, N 3.49; found C 76.31, H 9.37, N
3.33.
[C(CH3)3], 27.1 and 22.5 (CH2), 11.2 (CH2CH3) ppm. Minor iso-
mer: 1H NMR (400 MHz, C6D6, 25 °C): δ = 7.52 (d, 4JHH = 2.1 Hz,
4
4
1 H, CH-Ar), 7.48 (d, JHH = 2.1 Hz, 1 H, CH-Ar), 7.12 (d, JHH
[ZrL1Cl2] (6). Method A: A solution of H2L1 (1.35 g, 2.50 mmol) in
THF was added to a solution of Zr(CH2SiMe3)2Cl2(Et2O)2 (1.12 g,
2.50 mmol) in the same solvent. The mixture was stirred at room
temperature for 12 h and a white precipitate appeared. The yellow
solution was filtered and the solvents evaporated to dryness under
reduced pressure to give a light yellow solid in 48% yield.
4
= 1.9 Hz, 1 H, CH-Ar), 7.09 (d, JHH = 1.8 Hz, 1 H, CH-Ar), 5.68
(d, JHH = 14.2 Hz, 1 H, ArCH2N), 5.42 (d, JHH = 13.1 Hz, 1 H,
2
2
2
2
ArCH2N), 3.33 (d, JHH = 14.2 Hz, 1 H, ArCH2N), 3.25 (d, JHH
= 13.2 Hz, 1 H, ArCH2N), 1.74 [s, 9 H, C(CH3)3], 1.45 [s, 9 H,
C(CH3)3], 1.44 [s, 9 H, C(CH3)3], 1.40 [s, 9 H, C(CH3)3] ppm. The
other peaks are overlapped by the peaks of the major isomer. 13C-
{1H} NMR (101 MHz, C6D6, 25 °C): δ = 158.9, 157.6, 140.6, 140.5,
135.7 and 126.2 (Cipso-Ar), 126.2, 125.4 and 125.1 (CH-Ar), 125.0
(Cipso-Ar), 124.8 (CH-Ar), 66.6 (ArCH2N), 66.4 (CH), 66.2
(ArCH2N), 59.0, 51.4 and 49.2 (CH2), 36.0, 35.8, 35.7 and 34.7
[C(CH3)3], 32.4, 32.3, 31.9, 30.6 [C(CH3)3], 26.2 and 21.2 (CH2),
11.9 (CH2CH3) ppm. C37H58Cl2N2O2Zr·(C4H8O) (796.64): calcd.
C 57.02, H 7.69, N 3.74; found C 57.01, H 8.48, N 3.36.
Method B: A solution of H2L1 (323 mg, 0.6 mmol) in Et2O was
added to a solution of Zr(NMe2)4 (161 mg, 0.6 mmol) in the same
solvent. The mixture was stirred at room temperature for 2 h. The
yellow solution was evaporated to dryness under reduced pressure.
The residue was redissolved in CH2Cl2 and Si(Me)3Cl 1 m in
CH2Cl2 (2.4 mL, 2.4 mmol) was slowly added to the solution. The
mixture was stirred at room temperature for 2 h and the yellow
solution was evaporated to dryness under reduced pressure. The
residue was washed with n-hexane and dried in vacuo to give a
light yellow solid in 68% yield. 1H NMR (400 MHz, C6D6, 25 °C):
δ = 7.61 (s, 1 H, CH-Ar), 7.55 (s, 1 H, CH-Ar), 6.92 (s, 2 H, CH-
[ZrL1(CH2Ph)2] (8): A solution of H2L1 (456 mg, 1 mmol) in tolu-
ene was slowly added to a solution of Zr(CH2Ph)4 (539 mg,
1 mmol) in the same solvent. The solution was stirred at room tem-
perature for 2 h. All the volatiles were removed under reduced pres-
sure and the residue was washed with pentane to give a yellow
2
2
Ar), 4.41 (d, JHH = 14.1 Hz, 1 H, ArCH2N), 4.06 (d, JHH
=
14.3 Hz, 1 H, ArCH2N), 2.95 [m, 3 H, ArCH2N, NCH(CH3)-
1
solid; yield 670 mg, 83%. H NMR (500 MHz, C6D6, 25 °C): δ =
2
CH2N], 2.38 [t, JHH = 13.1 Hz, 1 H, NCH(CH3)CH2N], 2.09 [s, 3
4
7.73 (d, 3JHH = 7.4 Hz, 2 H, CH2Ph), 7.63 (d, JHH = 2.4 Hz, 1 H,
H, N(CH3)2], 1.71 [s, 18 H, C(CH3)3], 1.69 [s, 3 H, N(CH3)2], 1.39
4
3
CH-Ar), 7.58 (d, JHH = 2.4 Hz, 1 H, CH-Ar), 7.39 (t, JHH
=
2
[s, 9 H, C(CH3)3], 1.37 [s, 9 H, C(CH3)3], 0.75 [d, JHH = 13.0 Hz,
3
7.7 Hz, 2 H, CH2Ph), 7.04 (t, JHH = 7.3 Hz, 1 H, CH2Ph), 6.96
(d, JHH = 2.3 Hz, 1 H, CH-Ar), 6.90 (m, 3 H CH-Ar, CH2Ph),
3
1 H, NCH(CH3)CH2N], 0.54 [d, JHH = 6.6 Hz, 3 H, NCH(CH3)-
4
CH2N] ppm. 13C-{1H}NMR (101 MHz, C6D6, 25 °C): δ = 158.2,
156.9, 142.7, 142.5, 138.0, 136.9, 126.7 and 125.5 (Cipso-Ar), 125.5,
125.4, 125.1 and 124.7 (CH-Ar), 66.1 [NCH(CH3)CH2N], 62.5 and
58.1 (ArCH2N), 53.2 [NCH(CH3)CH2N], 51.7 and 48.2 [N-
(CH3)2], 36.1, 36.0, 34.9 and 34.8 [C(CH3)3], 32.3, 32.2,
31.4 and 31.0 [C(CH3)3], 8.3 [NCH(CH3)CH2N] ppm.
C35H56Cl2N2O2Zr·0.6(CH2Cl2) (749.51): calcd. C 57.02, H 7.69, N
3.74; found C 57.01, H 8.48, N 3.36.
6.72 (t, JHH = 7.6 Hz, 2 H, CH2Ph), 6.56 (t, JHH = 7.2 Hz, 1 H,
2
2
CH2Ph), 3.36 (d, JHH = 14.3 Hz, 1 H, ArCH2N), 3.06 (d, JHH
=
2
14.3 Hz, 1 H, ArCH2N), 2.90 (d, JHH = 14.3 Hz, 1 H, ArCH2N),
2.79 [m, 3 H, CH2Ph, ArCH2N, NCH(CH3)CH2N], 2.67 (m, 2 H,
CH2Ph), 2.55 (d, JHH = 9.8 Hz, 1 H, CH2Ph), 2.20 [t, JHH
2
2
=
13.0 Hz, 1 H, NCH(CH3)CH2N], 1.89 [s, 9 H, C(CH3)3], 1.88 [s, 9
H, C(CH3)3], 1.71 (s, 3 H, NCH3), 1.39 (s, 3 H, NCH3), 1.35 [s, 9
3
2
H, C(CH3)3], 1.34 [s, 9 H, C(CH3)3], 0.68 [dd, JHH = 3.0, JHH
3
[ZrL2Cl2] (7). Method A: A solution of H2L2 (1.41 g, 2.50 mmol) in
THF was added to a solution of Zr(CH2SiMe3)2Cl2(Et2O) (1.12 g,
2.50 mmol) in the same solvent. The mixture was stirred at room
temperature for 12 h and a white precipitate appeared. The yellow
solution was filtered and the solvents evaporated to dryness under
reduced pressure to give a light yellow solid; yield 0.28 g, 16%.
= 13.0 Hz, 1 H, NCH(CH3)CH2N], 0.62 [d, JHH = 6.7 Hz, 3 H,
NCH(CH3)CH2N] ppm. 13C-{1H} NMR (126 MHz, C6D6, 25 °C):
δ = 159.0 and 158.0 (Cipso-Ar), 150.2 and 148.0 (Cipso-Ph), 141.8,
141.4, 137.1 and 136.4 (Cipso-Ar), 128.8, 128.1, 127.8 and 127.6
(CH2Ph), 127.0 and 126.1 (Cipso-Ar), 125.2, 125.1, 124.9 and 124.7
(CH-Ar), 122.6 and 120.6 (CH2Ph), 68.6 (CH2Ph), 66.6 [CH2Ph,
NCH(CH3)CH2N], 61.0 and 57.2 (ArCH2N), 51.6 [NCH(CH3)-
CH2N], 49.7 and 46.7 [N(CH3)2], 36.1, 36.0, 34.8 and 34.7
Method B: A solution of H2L2 (339 mg, 0.6 mmol) in Et2O was
added to a solution of Zr(NMe2)4 (161 mg, 0.6 mmol) in the same
solvent. The solution was stirred at room temperature for 2 h. The
yellow solution was evaporated to dryness under reduced pressure.
The residue was redissolved in CH2Cl2 and Si(Me)3Cl 1 m in
CH2Cl2 (2.4 mL, 2.4 mmol) was slowly added to the solution. The
mixture was stirred at room temperature for 2 h. The yellow solu-
tion was evaporated to dryness under reduced pressure. The residue
was washed with n-hexane and dried in vacuo to give a light yellow
solid; yield 250 mg, 57%. The analysis of NMR spectroscopic data
revealed a mixture of isomers in variable ratios (from 100:1 to 3:1).
Major isomer: 1H NMR (400 MHz, C6D6, 25 °C): δ = 7.60 (s, 1 H,
CH-Ar), 7.58 (s, 1 H, CH-Ar), 7.05 (s, 1 H, CH-Ar), 6.94 (s, 1 H,
[C(CH3)3], 32.3, 31.3 and 31.0 [C(CH3)3], 8.2 [NCH(CH3)CH2N]
1
ppm. 13C NMR (101 MHz, C6D6, 25 °C): δ = 68.6 (t, JCH
=
1
123 Hz, ZrCH2Ph), 66.6 (t, JCH = 121 Hz, ZrCH2Ph) ppm.
C49H70N2O2Zr (809.77): calcd. C 72.63, H 8.71, N 3.46; found C
71.70, H 8.72, N 3.44; the low carbon content obtained results from
the extreme instability of the complex; although the NMR spectra
reveal the high purity of the compound (see Supporting Infor-
mation), attempts to obtain good elemental analysis failed.
[ZrL2(CH2Ph)2] (9). Method A: A solution of H2L2 (220 mg,
0.48 mmol) in toluene was slowly added to a solution of Zr-
(CH2Ph)4 (273 mg, 0.48 mmol) in the same solvent. After stirring
for 2 h at room temperature the volatiles were removed under re-
duced pressure and the residue was washed with pentane to give a
yellow solid; yield 404 mg, 70%.
2
2
CH-Ar), 4.79 (d, JHH = 13.8 Hz, 1 H, ArCH2N), 3.95 (d, JHH
=
13.1 Hz, 1 H, ArCH2N), 3.19 (m, 1 H, CH2CH3), 3.07 (m, 2 H,
ArCH2N, CH2), 2.89 (m, 2 H, ArCH2N, CH), 2.69 (m, 2 H, CH2),
2.20 (m, 1 H, CH2CH3), 1.74 [s, 18 H, C(CH3)3], 1.53 (m, 1 H, Method B: A 1 m solution of PhCH2MgCl in Et2O (0.56 mL,
CH2), 1.40 [s, 9 H, C(CH3)3], 1.35 [s, 9 H, C(CH3)3], 0.80 (m, 1 H, 0.51 mmol) was slowly added to a solution of 7 in Et2O (185 mg,
4286
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Eur. J. Inorg. Chem. 2011, 4277–4290

Chiral Diamine Bis(phenolate) TiIV and ZrIV Complexes
3
2
0.26 mmol) and the mixture was stirred for 2 h. The yellow solution
was filtered and the solvent removed under reduced pressure to
give a yellow solid; yield 213 mg, 59%. 1H NMR (500 MHz, C6D6,
H, JHH = 7.3 Hz, CH2Ph), 3.61 (d, 1 H, JHH = 14.3 Hz,
2
ArCH2N), 3.51 (d, 1 H, JHH = 14.4 Hz, ArCH2N), 3.39 (d, 1 H,
2JHH = 14.5 Hz, ArCH2N), 3.31 (s, 2 H, BCH2Ph), 3.28 (d, 1 H,
2JHH = 14.5 Hz, ArCH2N), 2.98 [m, 1 H, NCH(CH3)CH2N], 2.94
3
25 °C): δ = 7.59 (m, 4 H, CH-Ar, CH2Ph), 7.37 (t, JHH = 7.7 Hz,
3
2 H, CH2Ph), 7.02 (t, JHH = 7.1 Hz, 1 H, CH2Ph), 6.94 (m, 3 H, (s, 2 H, ZrCH2Ph), 2.47 [m, 1 H, NCH(CH3)CH2N], 2.04 [s, 3 H,
3
CH-Ar, CH2Ph), 6.86 (s, 1 H, CH-Ar), 6.76 (t, JHH = 7.6 Hz, 2
N(CH3)2], 1.77 [s, 3 H, N(CH3)2], 1.52 [s, 18 H, C(CH3)3], 1.33 [m,
1 H, NCH(CH3)CH2], 1.32 [s, 9 H, C(CH3)3], 1.30 [s, 9 H,
3
2
H, CH2Ph), 6.59 (t, JHH = 6.9 Hz, 1 H, CH2Ph), 3.64 (d, JHH
=
3
13.4 Hz, 1 H, ArCH2N), 2.93 (m, 2 H, ArCH2N, CH2Ph), 2.86 (m,
2 H, CH2Ph, CH2), 2.79 (m, 2 H, CH2Ph), 2.73 (m, 2 H, ArCH2N,
C(CH3)3], 0.92 [d, 3 H, JHH = 6.6 Hz, NCH(CH3)CH2N] ppm.
13C–{1H} NMR (126 MHz, C6D5Br, 25 °C): δ 155.5 and 154.8
CH), 2.58 (m, 2 H, ArCH2N, CH2), 2.37 (m, 2 H, CH2), 2.24 (m, (Cipso-Ar), 149.5 [br., B(C6F5)3], 148.8 (Cipso-PhCH2B), 147.6 [br.,
1 H, CH2), 1.91 [s, 9 H, C(CH3)3], 1.79 [s, 9 H, C(CH3)3], 1.35 [s, B(C6F5)3], 144.8 and 144.7 (Cipso-Ar), 138.5, 137.5 and 136.5 [br.,
9 H, C(CH3)3], 1.34 [s, 9 H, C(CH3)3], 1.29 (m, 1 H, CH2), 0.88 B(C6F5)3], 135.8 (Cipso-Ar), 135.5 [br., B(C6F5)3], 135.2 (Cipso-Ar),
2
(m, 2 H, CH2), 0.68 (m, 1 H, CH2), 0.36 (t, JHH = 10.9 Hz, 1 H,
134.3 and 131.8 (CH2Ph), 131.6 (Cipso-PhCH2Zr), 131.2, 129.6,
128.9, 127.0 and 126.4 (CH2Ph), 125.6 and 125.5 (CH-Ar), 125.2
CH2), 0.29 (t, 3JHH = 7.3 Hz, 3 H, CH2CH3) ppm. 13C–{1H} NMR
(126 MHz, C6D6, 25 °C): δ = 158.6 and 157.4 (Cipso-Ar), 148.9 and (Cipso-Ar), 125.2 and 125.0 (CH-Ar), 124.3 (Cipso-Ar), 122.6, 122.5
148.6 (Cipso-Ph), 141.9, 141.5, 137.1 and 136.6 (Cipso-Ar), 129.2,
128.7, 128.2 and 127.9 (CH2Ph), 126.6 and 126.1 (Cipso-Ar), 125.2,
124.7 and 124.3 (CH-Ar), 122.2 and 120.7 (CH2Ph), 69.1 and 68.3
(CH2Ph), 65.7 and 64.6 (ArCH2N), 64.2 (CH), 60.0, 52.2 and 51.9
(CH2), 36.1, 36.0, 34.8 and 34.7 [C(CH3)3], 32.3, 32.2, 31.3, 31.1
and 121.9 (CH2Ph), 72.6 (ZrCH2Ph), 67.5 [NCH(CH3)CH2N], 60.9
(ArCH2N), 57.0 (ArCH2N), 52.3 [NCH(CH3)CH2N], 52.0 and 47.4
[N(CH3)2], 35.0, 34.9 and 34.2 [C(CH3)3], 31.45 (BCH2Ph), 31.33,
31.29 and 30.0 [C(CH3)3], 7.4 [NCH(CH3)CH2N] ppm. 13C NMR
1
(126 MHz, C6D5Br, 25 °C): δ 72.6 (t, JCH = 139 Hz, ZrCH2Ph)
[C(CH3)3], 28.7 and 23.6 (CH2), 11.7 (CH2CH3) ppm. 13C NMR ppm. 19F NMR (376 MHz, C6D5Br, 25 °C): δ –130.16 (d, 6 F, 3JFF
1
3
(101 MHz, C6D6, 25 °C): δ = 69.1 (t, JCH = 124 Hz, ZrCH2Ph), = 22.6 Hz, o-C6F5), –163.59 (t, 3 F, JFF = 22.6 Hz, p-C6F5),
1
3
68.3 (t, JCH = 112 Hz, ZrCH2Ph) ppm. EA calculated for
–166.30 (t, 6 F, JFF = 22.6 Hz, m-C6F5) ppm. [|Δδ(m,p-F)|] = 2.71.
C51H72N2O2Zr (835.78): C 73.24, H 8.68, N 3.35; found C 71.34,
H 8.65, N 3.34; the low carbon content obtained results from the
extreme instability of the complex; although the NMR spectra re-
veal the high purity of the compound (see Supporting Infor-
mation), attempts to obtain good elemental analysis failed.
[ZrL2(CH2Ph)][PhCH2B(C6F5)3] (12): In a NMR tube, 9 (7.00 mg,
8.37 μmol) was treated with one equivalent of B(C6F5)3 (4.28 mg,
8.37 μmol) in C6D5Br (0.6 mL). After 10 min, the NMR spectrum
of the light yellow solution revealed the quantitative formation of
12. 1H NMR (500 MHz, C6D5Br, 25 °C): δ = 7.43 (m, 5 H, CH-
[TiL1(CH2Ph)][PhCH2B(C6F5)3] (10): In a NMR tube, 5 (7.00 mg, Ar, CH2Ph), 7.37 (s, 1 H, CH-Ar), 7.25 (s, 1 H, CH-Ar), 7.13 (d,
9.13 μmol) was treated with one equivalent of B(C6F5)3 (4.67 mg,
9.13 μmol) in C6D5Br (0.6 mL). After 10 min, the NMR spectrum
of the dark orange solution revealed the quantitative formation of
3JHH = 7.2 Hz, 3 H, CH2Ph), 6.96 (m, 2 H, CH2Ph), 6.85 (s, 1 H,
3
2
CH-Ar), 6.81 (t, JHH = 7.1 Hz, 1 H, CH2Ph), 4.42 (d, JHH
=
=
=
2
13.4 Hz, 1 H, ArCH2N), 3.62 (m, 1 H, CH), 3.52 (d, JHH
10. 1H NMR (500 MHz, C6D5Br, 25 °C): δ = 7.44 (s, 1 H, CH-Ar), 14.8 Hz, 1 H, ArCH2N), 3.33 (s, 2 H, BCH2Ph), 3.17 (d, JHH
2
2
7.39 (s, 1 H, CH-Ar), 7.27 (m, 4 H, CH2Ph), 7.23 (s, 1 H, CH-Ar),
7.10 (m, 2 H, CH2Ph), 7.06 (m, 1 H, CH2Ph), 6.92 (m, 2 H,
14.9 Hz, 1 H, ArCH2N), 3.10 (d, JHH = 13.5 Hz, 1 H, ArCH2N),
2.97 (m, 1 H, CH2), 2.73 (t, JHH = 9.1 Hz, 1 H, CH2), 2.55 (s, 2
3
CH2Ph), 6.83 (s, 1 H, CH-Ar), 6.78 (t, 3JHH = 6.5 Hz, 1 H, CH2Ph), H, ZrCH2Ph), 2.49 (t, JHH = 13.5 Hz, 1 H, CH2), 2.40 (m, 2 H,
2
2
3.77 (d, JHH = 14.1 Hz, 1 H, ArCH2N), 3.70 (m, 2 H, ArCH2N), CH2CH3), 2.02 (d, 2JHH = 13.4 Hz, 1 H, CH2), 1.69 (m, 1 H, CH2),
2
3.36 (d, JHH = 13.9 Hz, 1 H, ArCH2N), 3.29 (s, 2 H, BCH2Ph),
1.47 (m, 1 H, CH2), 1.34 [s, 9 H, C(CH3)3], 1.27 [s, 9 H, C(CH3)3],
3.25 (s,
2
H, TiCH2Ph), 2.90 [m,
2
H, NCH(CH3)CH2N,
1.23 [s, 9 H, C(CH3)3], 120 [s, 9 H, C(CH3)3], 1.20 (1 H, CH2), 0.97
3
NCH(CH3)CH2N], 2.22 [s, 3 H, N(CH3)2], 2.19 [s, 3 H, N(CH3)2], (t, JHH = 6.8 Hz, 1 H, CH2CH3), 0.90 (m, 1 H, CH2) ppm. 13C-
2.09 [m, 1 H, NCH(CH3)CH2N], 1.46, 1.37, 1.32 and 1.20 [s, 9 H,
{1H} NMR (126 MHz, C6D5Br, 25 °C): δ = 157.7 and 155.3 (Cipso
-
Ar), 149.4 [br., B(C6F5)3], 148.6 (Cipso-PhCH2B), 147.5 [br.,
B(C6F5)3], 145.5 and 145.4 (Cipso-Ar), 138.5 and 137.5 [br.,
3
C(CH3)3], 0.74 [d, JHH = 4.4 Hz, 3 H, NCH(CH3)CH2N] ppm.
13C-{1H} NMR (126 MHz, C6D5Br, 25 °C): δ = 161.7 and 159.7
(Cipso-Ar), 149.4 [br., B(C6F5)3], 148.6 (Cipso-PhCH2B), 147.6 [br.,
B(C6F5)3], 136.8 (Cipso-Ar), and 136.5 [br., B(C6F5)3], 136.1 (Cipso
-
B(C6F5)3], 147.4 (Cipso-PhCH2Ti), 147.4 and 145.2 (Cipso-Ar), Ar), 135.8 (Cipso-PhCH2Zr), 135.5 [br., B(C6F5)3], 132.9, 131.2,
138.5, 137.4, 136.5 and 135.5 [br., B(C6F5)3], 135.1 and 134.8 (Cipso
Ar), 131.2, 129.6, 128.8, 128.4, 128.2, 127.8, 127.0, 126.4 and 125.8
(CH2Ph), 125.1, 124.9 and 124.8 (CH-Ar), 123.8 and 123.6 (Cipso
-
129.6, 128.8, 128.4, 127.1 and 126.4 (CH2Ph), 125.4 and 125.2
(CH-Ar), 122.8 and 122.4 (CH2Ph), 122.0 (Cipso-Ar), 121.9 (CH-
Ar), 121.6 (Cipso-Ar), 68.8 (ZrCH2Ph), 64.4 (CH), 59.2 and 58.3
-
Ar), 122.7 (CH2Ph), 104.0 (ArCH2N), 68.6 [NCH(CH3)CH2N], (ArCH2N), 56.6 and 55.5 (CH2), 52.9 (CH2CH3), 34.8, 34.5, 34.3
55.6 (TiCH2Ph), 52.4 [NCH(CH3)CH2N], 50.2 [N(CH3)2], 49.8 and 34.1 [C(CH3)3], 31.4 (BCH2Ph), 31.3, 31.2, 30.2 and 29.7
(ArCH2N), 47.9 [N(CH3)2], 34.9, 34.7, 34.5 and 34.3 [C(CH3)3],
31.4 (BCH2Ph), 31.2, 31.1, 29.9 and 29.8 [C(CH3)3], 7.0
[C(CH3)3], 24.3 and 21.5 (CH2), 14.6 (CH2CH3) ppm. 19F NMR
3
(376 MHz, C6D5Br, 25 °C): δ = –130.68 (d, JFF = 22.6 Hz, 6 F, o-
3
3
[NCH(CH3)CH2N] ppm. 19F NMR (376 MHz, C6D5Br, 25 °C): δ C6F5), –163.60 (t, JFF = 18.8 Hz, 3 F, p-C6F5), –166.44 (t, JFF
=
= –130.59 (br., 6 F, o-C6F5), –163.66 (br., 3 F, p-C6F5), –166.46 (br.,
6 F, m-C6F5) ppm. [|Δδ(m,p-F)|] = 2.80.
[ZrL1(CH2Ph)][PhCH2B(C6F5)3] (11): In a NMR tube, 8 (8.00 mg,
9.87 μmol) was treated with one equivalent of B(C6F5)3 (5.00 mg,
9.87 μmol) in C6D5Br (0.6 mL). After 10 min, the NMR spectrum
22.6 Hz, 6 F, m-C6F5) ppm. [|Δδ(m,p-F)|] = 2.84.
[ZrL1(CH2Ph)][B(C6F5)4] (13): In
a
NMR tube,
8
(7.00 mg,
8.64 μmol) was treated with one equivalent of [PhNMe2H][B-
(C6F5)4] (6.92 mg, 8.64 μmol) in C6D5Br (0.6 mL). After 10 min,
the NMR spectrum of the light yellow solution revealed the quanti-
tative formation of 13, toluene and free PhNMe2. 1H NMR
of the light yellow solution revealed the quantitative formation of
1
11. H NMR (500 MHz, C6D5Br, 25 °C): δ 7.50 (m, 4 H, CH-Ar, (500 MHz, C6D5Br, 25 °C): δ = 7.54 (m, 4 H, CH-Ar, CH2Ph), 7.18
3
CH2Ph), 7.19 (t, 2 H, JHH = 7.5 Hz, CH2Ph), 7.11 (m, 3 H,
[m, 6 H, NPh(CH3)2, CH3Ph, CH2Ph], 7.07 (m, 5 H, CH-Ar,
4
4
CH2Ph), 7.07 (d, 1 H, JHH = 1.9 Hz, CH-Ar), 6.99 (d, 1 H, JHH CH2Ph, CH3Ph), 6.98 (s, 1 H, CH-Ar), 6.80 [t, 1 H, 3JHH = 7.1 Hz,
3
2
= 2.1 Hz, CH-Ar), 6.92 (t, 2 H, JHH = 7.6 Hz, CH2Ph), 6.77 (t, 1
NPh(CH3)2], 6.60 [m, 2 H, NPh(CH3)2], 3.55 (d, 1 H, JHH
=
Eur. J. Inorg. Chem. 2011, 4277–4290
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4287

A. M. Martins et al.
FULL PAPER
2
14.3 Hz, ArCH2N), 3.46 (d, 1 H, JHH = 14.4 Hz, ArCH2N), 3.33
[PhNMe2H][B(C6F5)4] solution (0.5 mL) and then pressurized with
the monomer to a pressure of 5 bar. The mixture in the reactor
2
2
(d, 1 H, JHH = 14.2 Hz, ArCH2N), 3.21 (d, 1 H, JHH = 14.3 Hz,
ArCH2N), 2.94 [m, 3 H, NCH(CH3)CH2N, ZrCH2Ph], 2.56 [s, 6 was stirred for 30 min with continuous supply of monomer. The
2
H, NPh(CH3)2], 2.45 [t, 1 H, JHH = 13.3 Hz, NCH(CH3)CH2N], polymerization was ended by venting the reactor and subsequent
2.18 (s, 3 H, CH3Ph), 2.00 [s, 3 H, N(CH3)2], 1.72 [s, 3 H, addition of acidified methanol (5% HCl).
N(CH3)2], 1.54 [s, 9 H, C(CH3)3], 1.53 [s, 9 H, C(CH3)3], 1.34 [s, 9
Polyethylene: The polymeric material was collected and washed sev-
eral times with ethanol and dried in a vacuum oven at 80 °C over-
night. The polymer was analyzed by HT-GPC.
H, C(CH3)3], 1.33 [s, 9 H, C(CH3)3], 1.26 [m, 1 H, NCH(CH3)-
CH2N], 0.88 [d, 3 H, 3JHH = 6.4 Hz, NCH(CH3)CH2N] ppm. 13C-
{1H} NMR (126 MHz, C6D5Br, 25 °C): δ = 155.6 and 154.9 (Cipso
-
Polypropylene: The polymeric material was poured into ca. 100 mL
of stirring ethanol and the solvents were removed under reduced
pressure. The polymer was analyzed by HT-GPC and 13C-{1H}
NMR spectroscopy. Typical NMR analysis of the samples showed
that the polypropylene obtained is atactic.
Ar), 149.5 and 147.5 [br., B(C6F5)3], 144.9 and 144.8 (Cipso-Ar),
139.3 [br., B(C6F5)3], 137.4 [br., B(C6F5)3], 135.9 (Cipso-Ar), 135.5
[br., B(C6F5)3], 135.2 (Cipso-Ar), 134.2 and 131.8 (Ph), 131.5 (Cipso
-
PhCH2Zr), 131.2, 129.6, 129.2, 128.9, 128.1 and 127.9 (Ph), 126.4,
125.5 and 125.3 (CH-Ar), 125.2 (Cipso-Ar), 124.9 (CH-Ar), 124.2
(Cipso-Ar), 122.4, 121.9, 118.5 and 113.3 (Ph), 72.5 (ZrCH2Ph), 67.4
[NCH(CH3)CH2N], 60.8 and 56.8 (ArCH2N), 52.2 [NCH(CH3)-
CH2N], 51.9 and 47.3 [N(CH3)2], 41.0 [NPh(CH3)2], 35.0, 34.9 and
34.2 [C(CH3)3], 31.23, 31.18 and 30.0 [C(CH3)3], 21.2 (CH3Ph), 7.1
[NCH(CH3)CH2N] ppm. 19F NMR (470 MHz, C6D5Br, 25 °C): δ
General Procedure for 1-Hexene Polymerization: A solution of pre-
catalyst (0.5 mL, 0.01 m in bromobenzene) was dissolved in 1-hex-
ene (9 mL) at room temperature under nitrogen and then a solution
of B(C6F5)3 (0.5 mL, 0.01 m in bromobenzene) was added. The re-
action mixture was stirred for 30 min. The solvent and remaining
monomer were removed under reduced pressure to yield poly(1-
hexene) as a colourless sticky oil. The polymer was analyzed by
HT-GPC and 13C-{1H} NMR spectroscopy. 13C-{1H} NMR
(500 MHz, CD2Cl2CD2Cl2, ppm): δ = 40.4 (br., CH2), 34.3 (br.,
CH2), 32.4 (CH), 28.7 (CH2), 28.4 (CH2), 23.5 (CH2), 14.5 (CH3)
ppm.
3
= –132.14 (br., 8 F, o-C6F5), –162.54 (t, 4 F, JFF = 23.5 Hz, p-
3
C6F5), –166.38 (t, 8 F, JFF = 18.8 Hz, m-C6F5) ppm.
General Procedure for Small-Scale Ethylene and Propylene Polyme-
rization: In the glovebox, precatalyst stock solutions were prepared
(0.01 m) in toluene (2 mL, 6 and 7) or bromobenzene (2 mL, 5, 8
and 9) and stored at –37 °C. B(C6F5)3, [PhNMe2H][B(C6F5)4]
(0.01 m in bromobenzene) and TIBAO (0.1 m in toluene) stock
solutions were also prepared and stored. In the polymerization runs
with 6 and 7, a 100 mL Büchi glass autoclave containing one Tef-
lon®-coated stirrer bar was charged with dry toluene (9 mL), pre-
catalyst solution (0.5 mL) and MMAO (0.533 mL, 7 % Al in hept-
anes) and then pressurized with 5 bar of the monomer. In the poly-
merization runs with 5, 8 and 9, a 100 mL Büchi glass autoclave
with a Teflon® coated stirrer bar was charged with dry toluene
(9 mL), precatalyst solution (0.5 mL) and B(C6F5)3 or
[PhNMe2H][B(C6F5)4] solution (0.5 mL) and then pressurized with
the monomer to a pressure of 5 bar. When TIBAO was added as a
scavenger the autoclaves were charged with toluene (8 mL), precat-
alyst solution (0.5 mL), TIBAO solution (1 mL) and B(C6F5)3 or
General Procedures for X-ray Crystallography: Colourless crystals
of H2L1 and H2L2 were obtained from methanol solutions at room
temperature. Crystals of 3 (orange), 6 (colourless) and 8 (yellow)
were grown from toluene solutions –37 °C. Crystallographic data
were collected at Instituto Superior Técnico and at the University
of Groningen. Crystals of air/moisture sensitive compounds were
selected inside the glovebox, covered with polyfluoroether oil and
mounted on a nylon loop. The data were collected using graphite
monochromated Mo-Kα radiation (λ = 0.71073 Å) with Bruker
AXS-KAPPA APEX II and Bruker SMART APEX CCD dif-
fractometers equipped with an Oxford Cryosystem open-flow ni-
trogen cryostat. Cell parameters were retrieved using Bruker
SMART software and refined using Bruker SAINT on all observed
Table 4. Selected crystallographic experimental data and structure refinement parameters for H2L1, H2L2, 3, 6 and 8.
H2L1
H2L2
3
6
8
Empirical formula
Formula weight
Temperature [K]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C35H58N2O2
538.83
150(2)
orthorhombic
Pbca
29.284(4)
14.6150(17)
31.861(4)
90
90
90
13636(3)
16, 1.050
0.064
C37H60N2O2
564.87
150(2)
monoclinic
P21
15.2340(15)
29.903(3)
15.4060(18)
90
95.267(6)
90
6988.5(13)
8, 1.074
0.065
C40H65ClN2O3Ti·(C7H8) C35H56Cl2N2O2Zr
C49H10N2O2Zr·(C7H8)
902.47
100(1)
monoclinic
P21/c
10.5347(15)
24.979(4)
18.993(3)
90
90.602(2)
90
4997.7(13)
4, 1.199
0.261
797.43
697.93
100(1)
150(2)
triclinic
P1
monoclinic
P21/c
9.669(3)
11.044(4)
11.694(4)
99.800(5)
109.598(4)
93.657(4)
1149.4(7)
1, 1.152
0.284
15.7740(11)
16.1970(11)
18.4740(13)
90
99.864(3)
90
4650.2(6)
4, 0.997
0.376
γ [°]
V [Å3]
Z, ρcalc [gcm–3]
μ [mm–1]
Crystal size
Crystal colour
Crystal shape
Reflections collected
Unique refl. [R(int)]
R1 [IϾ2σ(I)]
wR2 [IϾ2σ(I)]
GooF
0.40ϫ0.30ϫ0.20
colourless
block
131094
12088 [0.1741]
0.0567
0.30ϫ0.25ϫ0.25
colourless
block
97609
23828 [0.0783]
0.0577
0.38ϫ0.32ϫ0.23
orange
block
7448
5928 [0.0390]
0.1014
0.40ϫ0.20ϫ0.05
colourless
plate
68995
8138 [0.0743]
0.1073
0.53ϫ0.44ϫ0.35
yellow
block
40092
10518 [0.0390]
0.0422
0.1142
0.941
0.1247
0.999
0.3063
1.802
0.2484
1.317
0.0996
1.048
Flack’s parameter
0.6(9)
0.04(8)
4288
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 4277–4290

Chiral Diamine Bis(phenolate) TiIV and ZrIV Complexes
reflections. Absorption corrections were applied using SADABS.[22]
The structures were solved and refined using direct methods with
programs SIR97,[23] SIR2004[24] or SHELXS-97.[25] All programs
are included in the package of programs WINGX-Version
1.80.01[26] SHELXL.[27] Unless stated otherwise, all non-hydrogen
atoms were refined anisotropically and the hydrogen atoms were
inserted in idealized positions and allowed to refine riding on the
parent carbon atom. Molecular diagrams were drawn with OR-
TEP-3 for Windows[28] or Mercury 1.4.2,[29] included in the soft-
ware package. Compound 3 crystallizes in a noncentrosymmetric
space group and the refinement of the Flack[30] parameter x re-
sulted in a value of 0.04(8). H2L2 cristallizes in a noncentrosym-
metric space group but the absolute configuration could not be
confirmed as the Friedel pairs were not measured, furthermore as
there were no heavy atoms in the molecule, no significant anoma-
lous dispersion could be obtained using Mo radiation. The poor
quality of the crystals of 3 and 6 led to low quality data. The struc-
tures are included, as they are good enough to confirm the connec-
tivity. Crystallographic data for H2L1, H2L2, 3, 6 and 8 are pre-
sented in Table 4.
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Received: May 4, 2011
Published Online: August 12, 2011
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Eur. J. Inorg. Chem. 2011, 4277–4290