Monocyclopentadienyl phenoxido-amino and phenoxido-amido titanium complexes: Synthesis, characterisation, and reactivity of asymmetric metal centre derivatives

Article abstract of DOI:10.1002/ejic.200800553

Reduction of phenol-imine derivatives R′N=CH(3,5-R₂C ₆H₂-2-OH) (R = tBu; R′ = C₆H₅ 1a, p-MeC₆H₄ 1b, Cy 1c, tBu 1d, 2,6-Me₂C ₆H₃ 1e; R = H; R′ = p

Full text of DOI:10.1002/ejic.200800553

FULL PAPER
DOI: 10.1002/ejic.200800553
Monocyclopentadienyl Phenoxido–Amino and Phenoxido–Amido Titanium
Complexes: Synthesis, Characterisation, and Reactivity of Asymmetric Metal
Centre Derivatives
Giuseppe Alesso,[a] Martial Sanz,[a] Marta E. G. Mosquera,[a][‡] and and Tomás Cuenca*[a]
Keywords: Titanium / Asymmetry / N,O ligands / Polymerisation
Reduction of phenol–imine derivatives RЈN=CH(3,5-R2C6H2-
2-OH) (R = tBu; RЈ = C6H5 1a, p-MeC6H4 1b, Cy 1c, tBu 1d,
2,6-Me2C6H3 1e; R = H; RЈ = p-MeC6H4 1f; Cy = cyclohexyl)
with MBH4 (M = Li, Na) or AlLiH4 in ethyl ether or thf at
room temperature affords the phenol–amine compounds
RЈNHCH2(3,5-R2C6H2-2-OH) 2a–c and 2e,f. The N-R-[2,4-di-
tert-butyl]benzo-1-oxa-3-azine species (R = tBu 2d1, 2,6-
Me2C6H3 2e1) are obtained by Mannich reaction of 2,4-di-
tert-butylphenol with RNH2 in refluxing methanol. Interme-
diate 2d1 is converted in ethanol at room temperature into
N-tert-butyl[2-hydroxy-3,5-di-tert-butyl]benzylamine (2d),
whereas 2e is not obtained from 2e1 by using this procedure.
Cl (4a) results from the reaction of 2a with Ti(η5-C5H4Si-
Me2Cl)Cl3. Nevertheless, 2d reacts with TiCpCl3 in hexane
in the presence of NEt3 at room temperature yielding the
monocyclopentadienyl phenoxido dichloride compound
TiCp[tBuNHCH2(3,5-tBu2C6H2-2-O)]Cl2 (5), whereas in ethyl
ether and in the absence of NEt3 adduct 5·HCl is obtained,
which is further converted into TiCp[tBuNCH2(3,5-
tBu2C6H2-2-O)]Cl (3d) by addition of a NEt3/ethyl ether solu-
tion. The reaction of TiCpCl3 with 2a in the presence of
2.5 equiv. of NEt3 in a polar solvent (thf, CH2Cl2 or toluene)
at room temperature affords TiCp[Ph(H)NCH2(3,5-tBu2C6H2-
2-O)]Cl (6a) as a mixture of two stereoisomers. All the re-
N-alkyl,N-tert-butyl[2-hydroxy-3,5-di-tert-butyl]benzylamine ported compounds were characterised by the usual analytical
compounds tBuN(R)CH2(3,5-tBu2C6H2-2-OH) (R = Me 2g, Et
2h, nPr 2i, CH2Ph 2j) are also prepared by the appropriate
synthetic method. Treatment of 2a–c with 1 equiv. of TiCpCl3
and spectroscopic methods and the molecular structures of
2a, 2d, 2e and 3d were determined by X-ray diffraction
analysis from suitable single crystals. Preliminary studies of
in the presence of 2.5 equiv. of NEt3 in hexane at room tem- catalytic activity for ethylene polymerisation by using solid
perature gives the monocyclopentadienyl phenoxido–amido
monochloride complexes TiCp[RЈNCH2(3,5-tBu2C6H2-2-O)]Cl
(RЈ = C6H5 3a, RЈ = p-MeC6H4 3b, RЈ = Cy 3c). The analogous
methylaluminoxane as cocatalyst were performed.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
complex Ti(η5-C5H4SiMe2Cl)[C6H5NCH2(3,5-tBu2C6H2-2-O)]- Germany, 2008)
thesis. Particularly interesting are ligands with nitrogen and
Introduction
oxygen as donor atoms, due to their mode of complexation
to an acidic metal centre. Examples of these ligands includ-
ing phenoxido–imino[2–9] are synthesised through well-es-
tablished synthetic methods from which group 4 metal com-
plexes with tunable electronic and coordination geometry
properties have been prepared. In recent years, we have re-
ported the synthesis of a series of cyclopentadienyl titanium
complexes containing chelating dialkoxido[10–12] and di-
amido[13,14] ligands and studied the nature of the catalytic
species in the α-olefin polymerisation processes generated
by the reaction of these complexes with aluminum and bo-
ron reagents as cocatalyst.[15]
In this paper we report the synthesis and characterisation
of secondary phenol–amine compounds RЈNHCH2(3,5-
R2C6H2-2-OH) obtained from the phenol–imine derivatives
RЈN=CH(3,5-R2C6H2-2-OH) and tertiary phenol–amine
compounds tBuN(R)CH2(3,5-tBu2C6H2-2-OH) derived
from the corresponding benzoxazine derivatives. Phenol–
amine molecules are used as ligand precursors to synthesise
phenoxido–amido TiCpR[RЈNCH2(3,5-tBu2C6H2-2-O)]Cl
Over the two last decades organometallic chemists in-
volved in polyolefin chemistry have mainly focused their at-
tention and efforts on designing organometallic systems
with a specific architecture, which depends on the nature of
the ligands. Investigation and applications in olefin catalysis
of new group 4 metal complexes containing heteroatom–
base ligands have progressed steadily with a view to prepare
new high-value-added materials compared to those ob-
tained by using the legendary Ziegler–Natta or [MCp2X2]
(X = halo, alkyl, aryl) metallocene precursors.[1] Prepara-
tion of nitrogen-, oxygen-, sulfur- and phosphorus-based
molecules encompasses a large proportion of preligand syn-
[a] Departamento de Química Inorgánica, Universidad de Alcalá,
Campus Universitario,
28871 Alcalá de Henares, Spain
Fax: +34-918854683
E-mail: tomas.cuenca@uah.es
[‡] Correspondence concerning the crystallography data should be
addressed to this author.
E-mail: martaeg.mosquera@uah.es
4638
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4638–4649

Monocyclopentadienyl Phenoxido–Amino and –Amido Ti Complexes
and phenoxido–amino TiCp[tBuNHCH2(3,5-tBu2C6H2- tallisation from ethanol at –10 °C (vide infra). Molecule 2g
2-O)]Cl2 titanium derivatives. Preliminary studies of cata- was synthesised from 2d1 by reduction with NaBH4 in etha-
lytic activity for ethylene polymerisation by using solid nol at room temperature[18] or, alternatively, by the direct
methylaluminoxane (sMAO) as cocatalyst were performed. Mannich reaction of 2,4-di-tert-butylphenol with a slight
excess of tBuNHMe and paraformaldehyde in refluxing
methanol and isolated as an analytically pure yellow oil in
80–90% yield after workup and purification. The analogous
Results and Discussion
N-alkyl,N-tert-butyl-[2-hydroxy-3,5-di-tert-butyl]benzylamine
Phenol–Amine Molecules as Precursors of Phenoxido–
Amido and Phenoxido–Amino Ligands
substances 2h–j were prepared from 2d1 by ring-opening–
nucleophilic attack[19–22] on the O,N-methylene carbon
Phenol–amine compounds 2a–c and 2e,f (Scheme 1) were atom at –78 or 0 °C with the appropriate alkyl reagent (2h:
isolated in high yield by reduction of the corresponding M = Li or MgCl, R = Me; 2i: M = MgCl, R = Et; 2j: M
phenol–imine derivatives 1 with MBH4 (M = Li, Na) or = Li, R = Ph) (Scheme 2). All compounds were isolated as
AlLiH4 in ethyl ether or thf at room temperature, in a sim- analytically pure yellow oils in good yields (2h: 83% yield;
ilar way to analogous procedures previously reported in the 2i: 78% yield; 2j: 72% yield) after workup and purification.
literature.[16,17] The Mannich reaction of 2,4-di-tert-bu-
Compounds 1 and 2 were obtained as solids or oils, and
tylphenol with RNH2 (R = tBu, 2,6-Me2C6H3) and para- they are soluble in aromatic, aliphatic and chlorinated hy-
formaldehyde in refluxing methanol afforded N-R-[2,4-di- drocarbon solvents. The analytical composition fits well
tert-butyl]benzo-1-oxa-3-azine species 2d1 and 2e1, which with the proposed formulations. The 1H NMR spectra
were isolated as pure substances after workup. Intermediate (CDCl3, 20 °C) of compound set 1 show low-field shifted
2d1 is converted at room temperature into N-tert-butyl-[2- resonances assignable to the –OH (δ = 11.62–14.56 ppm)
hydroxy-3,5-di-tert-butyl]benzylamine (2d) by using ethanol and –CH=N (δ = 8.32–9.85 ppm) protons. The presence of
with high dilution (Scheme 2), whereas 2e1 is not converted the amine group in compound set 2 promotes the disap-
into 2e by this procedure. Compound 2d is obtained as ana- pearance of the conjugate system in the organic molecules
lytically pure X-ray quality needles in 20% yield after crys- and, consequently, the high-field shift in the 1H NMR spec-
Scheme 1.
Scheme 2.
Eur. J. Inorg. Chem. 2008, 4638–4649
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4639

G. Alesso, M. Sanz, M. E. G. Mosquera, T. Cuenca
FULL PAPER
tra of the signals corresponding to the OH protons. The 1H listed in Table 1. The synthesis of compound 2d was pre-
NMR spectra of 2a–c and 2f exhibit the characteristic sig- viously published,[23,24] but no crystallographic data have
nals for the OH group at δ ≈ 8.50 ppm. However, the respec- been reported in the literature. In the three structures the
tive resonances for compounds 2d and 2e appear at δ = chiral N1 centres show a tetrahedral environment. For com-
11.32 ppm and δ = 10.27 ppm, respectively, due to the large pound 2d, the two possible enantiomers crystallised to-
steric hindrance of the amine substituents group. The NMR gether (2d and 2dЈ) and the racemic mixture appears in the
spectroscopic data of 2d in CDCl3 solution exhibit an iden- crystal. In the structure, the C10 and N1 atoms are disor-
tical nature for the main signals with slight differences in dered. When this disorder was treated, the disposition of
chemical shifts compared to those of 2d1. Resonances as- the atoms C10/N1 and C10Ј/N1Ј seems to be related to the
signable to the O,N-methylene protons, two AB patterns for existence of both enantiomers in the asymmetric unit as
the methine protons of the arene ring with coupling con- shown in Figure 1 (trying to solve the structure in a lower
4
stants J = 2.1 and 2.4 Hz and the two characteristic reso- symmetry space group gives a resolution model with worse
nances downfield shifted at δ = 78.2 and 54.3 ppm for the agreement values). For 2a and 2e, the presence of an aro-
O,N-methylene- and the quaternary carbon atoms of the matic substituent on the nitrogen atom provides an ad-
tert-butyl carbon atom linked to the nitrogen atom are ob- ditional chirality feature, as the orientation of the rings
served in the 1H and 13C{1H} NMR spectra of 2d1 in gives conformational chirality, rendering these compounds
CDCl3 solution. The signals for the –OH and N-methyl diastereomeric. Interestingly only one of the possible dia-
protons in the expected range δ = 4.64 and 2.23 ppm, stereomers crystallises; although due to the absence of
respectively, appear in the 1H NMR spectrum of 2g heavy atoms, a reliable absolute configuration cannot be de-
(CDCl3, 20 °C). Similarly, the NMR spectra of the N- termined. In the solid state, intramolecular hydrogen bond-
alkyl,N-tert-butyl[2-hydroxy-3,5-di-tert-butyl]benzylamine ing OH···N is observed for the three compounds, in agree-
series 2h–j exhibit characteristic signals for the protons and ment with the behaviour deduced in solution from NMR
the carbon atoms in the molecules.
spectroscopic studies. Although there are no crystallo-
The solid-state structures of compounds 2a, 2d and 2e graphic data for Mannich organic homologue molecules
were confirmed by single-crystal X-ray diffraction studies with a “CH2NR2” pendant arm, the molecular structures
(Figures 1 and 2). Selected bond lengths and angles are of analogous benzamide derivatives have been described,[25]
which present similarities in the structural parameters of
the phenolic skeleton and the N-alkylamino ends with that
observed for 2a, 2d and 2e.
Table 1. Selected interatomic distances [Å] and angles [°] for com-
pounds 2a, 2d/2dЈ and 2e.
Bonds
2a
2d
2dЈ
2e
O1–C1
1.387(3)
1.526(4)
1.473(3)
1.424(2)
2.806
1.370(2)
1.553(6)
1.427(6)
1.513(4)
2.716
1.370(2)
1.539(5)
1.484(6)
1.547(4)
2.628
1.385(4)
1.524(4)
1.494(4)
1.458(4)
2.777
C6–C10
C10–N1
N1–C11
O1···N1
Angles
N1–C10–C6
C11–N1–C10
C11–N1–H1
C10–N1–H1
O1–H2···N1
110.4(2)
118.9(2)
112(2)
113(2)
143
109.1(4)
115.0(4)
114(3)
108(2)
146
109.0(3)
109.1(3)
114(2)
111(2)
151
110.6(3)
115.5(5)
109(3)
106(3)
149
Figure 1. Molecular structures of 2d: (a) frontal view of the struc-
ture; (b) side view showing the disorder present in the structure; (c)
and (d) separated side view of both enantiomers 2d and 2dЈ (OR-
TEP view with 30% probability ellipsoids).
Figure 2. Molecular structures of 2a and 2e (a side view of 2e showing the disposition of the aromatic rings is included) (ORTEP view
with 30% probability ellipsoids).
4640
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4638–4649

Monocyclopentadienyl Phenoxido–Amino and –Amido Ti Complexes
Titanium Derivatives Containing Phenoxido–Amido and
Phenoxido–Amino Ligands
Compounds 2a–c react with 1 equiv. of TiCpRCl3 in the
presence of 2.5 equiv. of NEt3 in hexane at room tempera-
ture to give the monocyclopentadienyl phenoxido–amido
monochloride complexes TiCpR[RЈNCH2(3,5-tBu2C6H2-2-
O)]Cl (CpR = Cp, RЈ = C6H5 3a, p-MeC6H4 3b, Cy 3c;
CpR = η5-C5H4SiMe2Cl, RЈ = C6H5 4a) (Cy = cyclohexyl)
(Scheme 3), which exhibit an asymmetric titanium centre.
The formation of compounds 3a–c and 4a is interpreted as
a result of the combination of Ti–Cl bond aminolysis and
hydrolysis reactions. Nevertheless, depending on the reac-
tion conditions (solvent nature, temperature or phenol–
amine reagent) the hydrolysis reaction is favoured, leaving
the N–H phenol–amine group unreacted to yield phe-
noxido–amine derivatives. Thus, treatment of TiCpCl3 with
2d in hexane or pentane in the presence of NEt3 at room
temperature proceeds with the formation of the monocyclo-
pentadienyl phenoxido dichloride compound TiCp[tBu(H)-
NCH2(3,5-tBu2C6H2-2-O)]Cl2 (5; Scheme 4). In this case,
coordination of the amine group is hindered as a conse-
quence of the higher steric hindrance of the tert-butylamine
substituent relative to that of the amine substituents in 2a–
c. However, the same reaction carried out in refluxing hex-
ane or toluene gives a mixture of final products in which
the presence of 5 and the phenoxido–amido complex
TiCp[tBuNCH2(3,5-tBu2C6H2-2-O)]Cl (3d) is observed.
Adduct 5·HCl was obtained as a pure solid when TiCpCl3
was treated with 2d for 3 h in ethyl ether at room tempera-
ture in the absence of NEt3. The amine functionality of the
phenol–amine starting reagent is itself used as a base under
these conditions, scavenging the HCl generated in the reac-
tion to form the corresponding insoluble ammonium salt
5·HCl, thus preventing the formation of subsequent second-
ary reaction products. A sample of 5·HCl evolves through
the addition of a NEt3/ethyl ether solution into 3d, which
is obtained as the only analytically pure reaction product
after ca. 7 d (Scheme 4). Formation of mononuclear phe-
noxido–amido derivatives 3, instead of alternative dinuclear
complexes containing bridging ligand, is favoured in these
reactions due to the thermodynamic stability imposed by
the six-membered ring exhibited by these species and the
inherent entropy favourability.
Scheme 4.
formation of TiCp[Ph(H)NCH2(3,5-tBu2C6H2-2-O)]Cl2
(6a) stabilised by coordination of the phenoxido ligand and
the amine functionality. The NMR spectroscopic analysis
reveals that 6a, obtained according to this procedure, is in-
deed a mixture of two stereoisomers 6a-1 and 6a-2
(Scheme 5). Axial or equatorial coordination of the amine
nitrogen atom in a bipyramidal trigonal geometry around
the titanium centre is proposed.
The alkylation reactions of 3a–c with 1 equiv. of LiMe,
MgClMe or MgCl(CH2Ph) in hexane or ethyl ether at
–78 °C gave an unstable, intractable and unresolved mixture
1
of products whose H NMR spectra were regrettably unin-
formative, indicating the action of reduction processes.
Attempts to synthesise alkyl derivatives by treatment of
TiCpR3 (R = Me, CH2Ph) with 2 were also unsuccessful.
When 3d reacts with 1 equiv. of MgClMe at –78 °C in n-
hexane, the formation of the methyl complex
TiCp[tBuNCH2(3,5-tBu2C6H2-2-O)]Me was spectroscopi-
cally observed [1H NMR (300 MHz, C6D6) for
TiCp[tBuNCH2(3,5-tBu2C6H2-2-O)]Me: δ = 0.97 (s, 3 H,
Ti-CH3), 1.03, 1.47, and 1.74 (3ϫ9 H, s, C(CH3)3), 2.66
and 3.81 (2 H, AB system, JA,B = 16.5 Hz, CH2), 6.20 (s, 5
H, Cp), 7.29 (d, JH,H = 2.4 Hz, 1 H, PhO), 7.72 (d, JH,H
=
2.4 Hz, 1 H, PhO) ppm]. Repeated efforts to obtain this
compound as a pure sample on a preparative scale remain
unfruitful.
Compounds 3–6 are air sensitive but thermally stable in
solution and in the solid state, and they can be stored unal-
tered for weeks if strictly inert atmospheric conditions are
Scheme 3.
In contrast, the reaction of TiCpCl3 with 2a in the pres- maintained. They are soluble in aromatic and chlorinated
ence of 2.5 equiv. of NEt3 in a more polar solvent (thf, solvents but poorly soluble in aliphatic hydrocarbons. All
CH2Cl2 or toluene) at room temperature proceeds with the of these compounds were fully characterised by NMR spec-
Eur. J. Inorg. Chem. 2008, 4638–4649
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4641

G. Alesso, M. Sanz, M. E. G. Mosquera, T. Cuenca
FULL PAPER
Scheme 5.
troscopy and elemental analysis. The analytical composi- the nitrogen atom is coordinated to the metal centre. The
tion fits well the proposed formulations. In addition, the X- NMR spectroscopic features for 6a-1 are consistent with a
ray molecular structure of 3d is reported.
chiral species, which stems from the rigid coordination of
Compounds 3a–d and 4a are asymmetric metal-centred the amine functionality, thus preventing epimerisation at
derivatives. Their 1H NMR spectra (C6D6 or CDCl3, 20 °C; the amine nitrogen atom, as well as the diverse nature of
see Exp. Sect.) show AB spin systems (2J ≈ 16.5 Hz) for the amine substituents, which makes the nitrogen atom be-
the CH2 protons, two signals for the tert-butyl groups, two come a stereogenic centre. In contrast, the Cs symmetry
doublets (4J ≈ 2.4 Hz) for the phenoxido and the expected suggested for 6a-2 in solution can be explained by a non-
resonances for the N-R substituents protons. A singlet for rigid disposition involving a rapid decoordination/coordi-
1
the cyclopentadienyl ring protons in the H NMR spectra nation process of the pendant amine group leading to an
1
of 3a–d is also observed, whereas the H NMR spectrum equilibrium position of the methylene hydrogen atoms
of compound 4a exhibits an ABCD spin system for the cy- (Scheme 5). Similar behaviour has been observed for analo-
clopentadienyl ring and two singlets for the nonequivalent gous cyclopentadienyl titanium derivatives.[26–28] Such al-
SiMe2Cl group protons. These spectroscopic data are con- tered behaviour is due to the different trans influence de-
1
sistent with a dissymmetric geometry in solution. The H rived from the presence of a chloride or a cyclopentadienyl
NMR spectrum of 5 (C6D6, 20 °C) shows a broad signal at ligand located in the trans position with respect to the
δ = 7.65 ppm assignable to the NH proton (δ = 9.40 ppm amino functionality in 6a-1 and 6a-2, respectively.
for the NH·HCl protons in 5·HCl) and the methylene pro-
The molecular structure of TiCp[tBuNCH2(3,5-tBu2-
tons appear as a broad signal at δ = 3.87 pm (δ = 4.30 ppm C6H2-2-O)]Cl (3d) was confirmed by a single-crystal X-ray
for 5·HCl), high-field shifted relative to those of com- diffraction study. The metal is an asymmetric centre. A ra-
pounds 3 and 4 indicating that the nitrogen atom is not cemic mixture of the two possible enantiomers appears in
coordinated to the metal centre. The spectra of 5 and 5·HCl the unit cell, and Figure 3 illustrates the view of one of the
also display the expected resonances of the cyclopentadienyl two possible isomers. The compound is mononuclear and
ring, phenoxido and tert-butyl protons. Similar characteris- the coordination geometry around the titanium centre is
tic results were observed in the 13C{1H} NMR spectra un- similar to that observed in analogous TiCpL3 complexes.[29]
der the same conditions.
The angles around the nitrogen atom show the expected
The 1H NMR spectrum of 6a (C6D6, 20 °C) exhibits two values for geometry consistent with sp2 hybridisation. The
different sets of sharp signals indicating the presence of two Ti–N [1.9052(18) Å] and Ti–O [1.8528(15) Å] bond lengths
stereoisomers. Isomer 6a-1 shows an ABX spin system for are comparable to those present in derivatives with an ap-
the CH2NH fragment (pseudotriplet for the NH proton at preciable multiple bond character, suggesting pπ–dπ inter-
δ = 3.24 ppm and pseudodoublets for the methylene pro- actions.[30–35] Compared with similar dialkoxido or diamido
tons at δ = 4.26 and 4.46 ppm, with coupling constant val- derivatives TiCpЈ(ER)2Cl (E = N, O), previously prepared
3
2
ues of JA,X/B,X and JA,B of about 6.5 and 4.5 Hz, respec- in our group, the Ti–O bond length is clearly longer
tively). Isomer 6a-2 exhibits an AAЈX spin system for the [1.8528(15) Å vs. 1.801 Å average].[10,11] However, the Ti–N
CH2NH fragment (pseudotriplet for the NH proton at δ = distance remains nearly identical.[13] Finally, the Ti–O–CPh
–
3.71 ppm and pseudodoublet for the methylene protons at
C
Ph–Cmethylene–N core appears as a six-membered ring,
3
δ = 4.51 ppm with coupling constant values of JA,X
≈
where the sp3 methylene carbon atom is placed out of the
6.7 Hz). The NH resonances for both isomers appear con- plane defined by the rest of the atoms. The C–C distances
siderably shifted downfield with respect to that found for within the cyclopentadienyl ring, Ti–Cg(centroid) distance
free amine 2a and high-field shifted relative to that of 3a. and Ti–Cl bond length are within the range for monocyclo-
These spectroscopic data are in agreement with C1 and Cs pentadienyl and dicyclopentadienyl titanium com-
symmetry for 6a-1 and 6a-2, respectively, and indicate that plexes.[31,33]
4642
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4638–4649

Monocyclopentadienyl Phenoxido–Amino and –Amido Ti Complexes
pound decomposes at room temperature, and evolution by
ligand transfer from titanium to aluminum probably oc-
curred.[15]
The decreased trend in activity observed as the tempera-
ture is raised for these precatalysts in the α-olefin polymeri-
sation might be due to a catalytically active decomposition
process through ligand abstraction by MAO, which may
cause a partial or complete loss of the ligand resulting in
one or more inactive species for α-olefin polymerisa-
tion.[15,37] Compounds 3c and 3d are stabilised by coordina-
tion of phenoxido–amido ligands with higher N-donor abil-
ity compared with 3a and 4a, suggesting a more stable
methyltitanium species obtained under these polymerisation
reaction conditions. These results correlate well with those
observed in the alkylation reactions of 3 with LiMe,
Figure 3. ORTEP view of 3d with 30% probability ellipsoids. Se-
lected interatomic distances [Å] and angles [°]: Ti1–Cl1 2.3120(8),
Ti1–N1 1.9052(18), Ti1–O1 1.8528(15), Ti1–Cg 2.109, Cl1–Ti1–N1
106.99(6), Cl1–Ti1–O1 102.40(6), N1–Ti1–O1 94.14(7), Ti1–N1–
C10 109.40(13), Ti1–N1–C11 135.04(14), C11–N1–C10 114.48(16), MgClMe or MgCl(CH2Ph).
Ti1–O1–C1 130.37(13). Cg denotes the centroid of the Cp ligand.
The polyethylene samples obtained had melting points of
130–135 °C, characteristic of high-density polyethylene, and
remarkable differences in the ∆H enthalpy values and the
degree of crystallinity (α).
Olefin Polymerisation Studies
Given our interest in the polymerisation chemistry of
group 4 monocyclopentadienyl diamido[15] or dialkox-
ido[10,11] metal complexes, we undertook preliminary stud-
ies on α-olefin polymerisation process for these monocyclo-
pentadienyl phenoxido–amido compounds in the presence
of sMAO as cocatalyst.[36] Ethylene polymerisation was in-
vestigated by using 50 mL total volume of toluene with
10–4 mol of catalyst and a 400 sMAO/Ti molar ratio at
1 atm pressure for 15 min. The observed results show
averages of two or, in some cases, more polymerisation runs,
which showed good reproducibility. Polymerisation reac-
tions by using a lower solvent volume (10, 20, 30 or 40 mL)
were performed. The best reproducibility of the final re-
sults, maintaining the rest of the variables constant, was
obtained by using 50 mL of toluene.
Conclusions
In this report we provided a contribution to the synthesis
and characterisation of new and somewhat unusual phe-
noxido–amido and phenoxido–amino titanium complexes
containing asymmetric metal centres. The new complexes
are interesting from basic coordination chemistry perspec-
tives because only a few derivatives of this type are known.
Initial studies of their ethylene polymerisation performance
under MAO activation conditions have been developed.
Experimental Section
General Considerations: All manipulations and reactions of air-
and/or moisture-sensitive compounds were carried out under argon
The catalytic activity for complexes is sensitive to tem-
perature, increasing the polymerisation activity at low tem- (Air Liquid N45, O2: 1 ppm; H2O: 3 ppm) by using Schlenk and
high-vacuum line techniques or in a dry argon atmosphere MBraun
glove box model MB150B-G. All glassware was dried under vac-
uum with a heat gun and purged three times by using vacuum–
argon filling cycles. The solvents (Baker and SDS) used for flash
column chromatography and air- and/or moisture-sensitive com-
pounds were of reagent grade and, when necessary, were purified
by distillation under argon before use by employing the appropriate
drying agent, and collected under argon in a Schlenk-type vessel
followed by several freeze–thaw cycles when necessary. Methanol
and ethanol (SDS and Carlo Erba) were dried and purified accord-
peratures. No polymerisation was found when the reaction
was carried out at 50 °C, whereas activities at 20 °C
(1.0 kgPolmol–1 P–1 h–1 for 3a and 0.9 kgPolmol–1 P–1 h–1
for 4a) and 10 °C (18.4 kgPolmol–1 P–1 h–1 for 3a and
10.2 kgPolmol–1 P–1 h–1 for 4a) were observed. Compounds
3c and 3d are slightly more active than 3a and 4a under
similar reaction conditions, exhibiting higher activity at
20 °C (408.0 kgPolmol–1 P–1 h–1 for 3c and 187.3
kgPolmol–1 P–1 h–1 for 3d) than that at 10 °C (166.8
kgPolmol–1 P–1 h–1 for 3c and 98.0 kgPolmol–1 P–1 h–1 for ing to literature procedures.[38] Deuterated solvents were firstly de-
gassed by several freeze–thaw cycles, held at room temperature over
fresh activated 4 Å molecular sieves (10% w/v) for several days,
3d).
In an effort to model the nature of the catalytic species
generated in these catalyst systems, the reaction of phe-
and then stored at room temperature over freshly activated 4 Å
[39,40]
molecular sieves (10% w/v). Compounds TiCpCl3
and Ti(η5-
noxido–amido monochloride derivative 3a with sMAO was
C5H4SiMe2Cl)Cl3[41] were prepared by a known procedure. Aniline,
p-toluidine, cyclohexylamine, 2,6-dimethylaniline, 3,5-di-tert-butyl-
2-hydroxybenzaldehyde, salicylaldehyde, paraformaldehyde, 2,4-di-
tert-butylphenol, LiBH4, NaBH4 and AlLiH4, LiMe (1.6  solution
in Et2O) or MgClMe (3  solution in thf), MgClEt (2  solution
in Et2O) and LiPh [2  solution in cyclohexane/ethyl ether mixture
examined. Treatment, at –78 °C, of
a solution of
TiCp[PhNCH2(3,5-tBu2C6H2-2-O)]Cl in C6D6 with an ex-
cess amount of sMAO resulted in the immediate formation
of a dark solution generating the expected monomethyl tita-
nium
complex
TiCp[PhNCH2(3,5-tBu2C6H2-2-O)]Me
(monitoring by NMR spectroscopy). The methylated com- (Aldrich)] were used as received. tert-Butylamine and N-tert-butyl-
Eur. J. Inorg. Chem. 2008, 4638–4649
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4643

G. Alesso, M. Sanz, M. E. G. Mosquera, T. Cuenca
FULL PAPER
methylamine (Aldrich) were purified under argon according to lit-
erature procedures.[38] Solid AlMe3-free methylaluminoxane
(sMAO) was obtained from methylaluminoxane (MAO)
(CROMPTON, 10 wt.-% solution in toluene) by drying under re-
duced pressure at 50 °C to remove the uncoordinated AlMe3 and
used after washing with n-hexane and complete drying. Flash col-
umn chromatography purification was carried out using the Still’s
method[42] employing silica gel 60 (60 Å, 40–63 µm, 230–400 Mesh
ASTM, E. Merck), which was oven-dried before use. TLC analysis
was carried out by using precoated silica gel 60 F254 on aluminum
foil (60 Å, layer thickness 0.2 mm, E. Merck), oven-dried before
use with reproducible results. Usual detection means used for TLC
were successively UV254, I2 on silica gel, a 5% solution of phos-
phomolybdic acid (Fluka) in ethanol with heating. The IR spectra
were recorded at room temperature with a Perkin–Elmer Spectrum-
2000 FTIR spectrophotometer. C, H and N microanalyses were
performed with a Perkin–Elmer 240B and/or Heraeus CHN-O-Ra-
pid microanalyser. The NMR samples of air- and/or moisture-sen-
sitive compounds were prepared under argon at room temperature
in a 5 mm Wilmad 507-PP tubes fitted with a J. Young Teflon valve.
The NMR spectra were recorded with a Varian Mercury VX-300
PFG at 20 °C. The chemical shifts and coupling constant J are
quoted in ppm and in Hertz, respectively, and are referenced with
respect to residual proton and carbon resonances of the solvent
(CDCl3: 1H: 7.25 ppm, 13C: 77.1 ppm; C6D6: 1H: 7.15 ppm, 13C:
128.0 ppm), which is also referenced with respect to SiMe4. The
assignment of the signals in NMR spectra was made by using stan-
(300 MHz, CDCl3): δ = 1.18–1.83 (m, 10 H, cyclohexyl-H), 1.28 [s,
9 H, C(CH3)3], 1.43 [s, 9 H, C(CH3)3], 3.18 (m, 1 H, cyclohexyl-
H), 7.05 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 7.34 (d, JH,H
=
2.4 Hz, 1 H, m-H, PhOH), 8.35 (s, 1 H, CH), 14.04 (s, 1 H, OH)
ppm. C21H33NO (315.5): calcd. C 79.95, H 10.54, N 4.44; found C
80.11, H 10.85, N 4.41.
tBuN=CH(3,5-tBu2C6H2-2-OH) (1d): A procedure similar to that
described for 1a but with the use of tert-butylamine (10.5 mL,
100 mmol) and 3,5-di-tert-butyl-2-hydroxybenzaldehyde (23.43 g,
100 mmol) gave 1d (28.01 g, 96.7 mmol, 97% yield). 1H NMR
(300 MHz, CDCl3): δ = 1.29 [s, 9 H, C(CH3)3], 1.32 [s, 9 H,
C(CH3)3], 1.43 [s, 9 H, C(CH3)3], 7.07 (d, JH,H = 2.4 Hz, 1 H, m-
H, PhOH), 7.34 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 8.33 (s, 1 H,
CH), 14.56 (s, 1 H, OH) ppm. C19H31NO (289.5): calcd. C 78.84,
H 10.79, N 4.84; found C 79.01, H 10.63, N 4.67.
(2,6-Me2C6H3)N=CH(3,5-tBu2C6H2-2-OH) (1e): A procedure sim-
ilar to that described for 1a but with the use of 2,6-dimethylaniline
(12.3 mL, 100 mmol) and 3,5-di-tert-butyl-2-hydroxybenzaldehyde
(23.43 g, 100 mmol) gave 1e (31.15 g, 92.3 mmol, 92% yield). 1H
NMR (300 MHz, CDCl3): δ = 1.32 [s, 9 H, C(CH3)3], 1.48 [s, 9 H,
C(CH3)3], 2.20 [s, 6 H, 2 CH3-(2,6-Me2phenyl)], 6.98–7.09 (m, 3 H,
PhN), 7.13 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 7.46 (d, JH,H
=
2.4 Hz, 1 H, m-H, PhOH), 8.32 (s, 1 H, CH), 13.44 (s, 1 H, OH)
1
ppm. H NMR (300 MHz, C6D6): δ = 1.32 [s, 9 H, C(CH3)3], 1.65
[s, 9 H, C(CH3)3], 1.96 (s, 6 H, CH3), 6.92 (s, 3 H, PhN), 6.97 (d,
JH,H = 2.4 Hz, 1 H, m-H, PhOH), 7.63 (d, JH,H = 2.4 Hz, 1 H, m-
H, PhOH), 7.64 (s, 1 H, CH), 13.88 (s, 1 H, OH) ppm. C23H31NO
(337.5): calcd. C 81.85, H 9.26, N 4.15; found C 81.39, H 9.23, N
4.17.
1
dard Varian pulse sequences for all compounds and selective H–
1H homodecoupling for some. Melting points of solid samples
placed in a dried capillary tube sealed under high vacuum were
determined with a Bibby Stuart Scientific device with a heating rate
of 0.5 °Cmin–1 with reproducible and uncorrected results. The poor
solubility of the polymers in several solvents precluded analysis by
GPC.
(p-MeC6H4)N=CH(C6H4-2-OH) (1f): A procedure similar to that
described for 1a but with the use of p-toluidine (10.72 g, 100 mmol)
and salicylaldehyde (10.6 mL, 100 mmol) gave 1f (17.21 g,
1
81.5 mmol, 82% yield). H NMR (300 MHz, CDCl3): δ = 2.41 (s,
(C6H5)N=CH(3,5-tBu2C6H2-2-OH)
(1a):
Aniline
(9.2 mL,
3 H, CH3), 6.92–7.43 (m, 8 H, PhO, PhN), 8.65 (s, 1 H, CH), 13.42
(s, 1 H, OH) ppm. C14H13NO (211.1): calcd. C 79.59, H 6.20, N
6.63; found C 79.49, H 6.31, N 6.58.
100 mmol) was added under vigorous stirring to a solution of 3,5-
di-tert-butyl-2-hydroxybenzaldehyde (100 mmol, 23.43 g) in meth-
anol (250 mL), which was allowed to react for 12 h. The crystalline
orange solid was filtered, dried under reduced pressure and charac-
terised as 1a (29.41 g, 95.0 mmol, 95% yield). 1H NMR (300 MHz,
CDCl3): δ = 1.26 [s, 9 H, C(CH3)3], 1.31 [s, 9 H, C(CH3)3], 7.14–
7.21 (5 H, m. C6H5N), 7.32 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH),
7.57 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 9.85 (s, 1 H, CH), 11.62
(s, 1 H, OH) ppm. C21H29NO (309.4): calcd. C 81.51, H 8.79, N
4.53; found C 81.53, H 8.65, N 4.67.
(C6H5)N(H)CH2(3,5-tBu2C6H2-2-OH) (2a): Compound 1a
(15.47 g, 50 mmol) was added under vigorous stirring to a suspen-
sion of NaBH4 (2.36 g, 55.0 mmol) in thf (150 mL). The reaction
mixture was stirred for 12 h resulting in a white suspension, which
was treated with a 37% solution of HCl (dissolved in 30 mL of
water) until no effervescence was observed. After adding NH3 to
obtain a solution with pH 11, the solvent was completely removed
under reduced pressure. The solid residue was extracted into
CH2Cl2. The organic layer was isolated by filtration, dried with
Na2SO4 and filtered, and the solvent was evaporated until volatiles
were completely removed. The white solid obtained was poured
into methanol (30 mL) and stirred for 2 h and cooled to –40 °C for
1 h. After removal of the solvent by filtration and drying under
reduced pressure, a solid was isolated and characterised as 2a
(11.53 g, 37.0 mmol, 74% yield). 1H NMR (300 MHz, CDCl3): δ =
1.33 [s, 9 H, C(CH3)3], 1.49 [s, 9 H, C(CH3)3], 2.88 (br., 1 H, NH),
3.39 (s, 2 H, CH2), 6.86–7.31 (m, 5 H, PhN), 7.04 (d, JH,H = 2.4 Hz,
1 H, m-H, PhOH), 7.25 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 8.36
(p-MeC6H4)N=CH(3,5-tBu2C6H2-2-OH) (1b): A procedure similar
to that described for 1a but with the use of p-toluidine (10.72 g,
100 mmol) and 3,5-di-tert-butyl-2-hydroxybenzaldehyde (23.43 g,
100 mmol) gave 1b (30.96 g, 95.7 mmol, 96% yield). 1H NMR
(300 MHz, CDCl3): δ = 1.31 [s, 9 H, C(CH3)3], 1.46 [s, 9 H,
C(CH3)3], 2.36 (s, 3 H, CH3), 7.19 (m, 5 H, PhN, m-H, PhOH),
7.42 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 8.62 (s, 1 H, CH) ppm,
resonances for the OH protons not observed. 1H NMR (300 MHz,
C6D6): δ = 1.34 [s, 9 H, C(CH3)3], 1.69 [s, 9 H, C(CH3)3], 2.09 (s,
3 H, CH3), 6.90 (s, 4 H, PhN), 7.03 (d, JH,H = 2.4 Hz, 1 H, m-H,
PhOH), 7.63 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 8.16 (s, 1 H,
CH), 14.31 (s, 1 H, OH) ppm. C22H39NO (323.5): calcd. C 81.69,
H 9.04, N 4.33; found C 81.33, H 9.55, N 4.41.
1
(s, 1 H, OH) ppm. H NMR (300 MHz, C6D6): δ = 1.38 [s, 9 H,
C(CH3)3], 1.67 [s, 9 H, C(CH3)3], 2.82 (br., 1 H, NH), 3.80 (s, 2 H,
CH2), 6.40 (d, JH,H = 8.1 Hz, 2 H, o-H PhN), 6.74 (t, JH,H
=
CyN=CH(3,5-tBu2C6H2-2-OH) (1c): A procedure similar to that
described for 1a but with the use of cyclohexylamine (11.4 mL,
100 mmol) and 3,5-di-tert-butyl-2-hydroxybenzaldehyde (23.43 g,
100 mmol) gave 1c (28.15 g, 89.2 mmol, 89% yield). 1H NMR
7.4 Hz, 1 H, p-H PhN), 6.91 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH),
7.03 (d, JH,H = 7.7 Hz, 2 H, m-H PhN), 7.53 (d, JH,H = 2.4 Hz, 1
H, m-H, PhOH), 8.65 (s, 1 H, OH) ppm. C21H29NO (311.5): calcd.
C 80.98, H 9.38, N 4.50; found C 80.92, H 9.29, N 4.27.
4644
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4638–4649

Monocyclopentadienyl Phenoxido–Amino and –Amido Ti Complexes
(p-MeC6H4)N(H)CH2(3,5-tBu2C6H2-2-OH) (2b): A procedure sim-
ilar to that described for 2a but with the use of 1b (16.17 g,
50 mmol) and NaBH4 (2.36 g, 55 mmol) in thf (150 mL) gave 2b
(11.31 g, 34.5 mmol, 69% yield). 1H NMR (300 MHz, CDCl3): δ =
H, N-C(CH3)], 1.42 [s, 9 H, C(CH3)-phenol], 1.76 [s, 9 H, C(CH3)-
4
phenol], 3.52 (s, 2 H, N-CH2-benzene), 6.94 (d, J = 2.4 Hz, 1 H,
4
CH-arom), 7.52 (d, J = 2.4 Hz, 1 H, CH-arom), 11.32 (br., 1 H,
OH) ppm. 13C{1H} NMR (75 MHz, CDCl3): δ = 28.7 [N-
1.28 [s, 9 H, C(CH3)3], 1.40 [s, 9 H, C(CH3)3], 2.39 (s, 3 H, CH3), C(CH3)3], 29.7, 31.7 [C(CH3)3], 34.2, 34.9 [C(CH3)3], 46.8 (CH2),
3.75 (br., 1 H, NH), 4.33 (s, 2 H, CH2), 6.77 (d, JH,H = 8.4 Hz, 2 50.9 [N-C(CH3)3], 122.9 (CH), 123.0 (Cipso), 123.1 (CH), 136.0,
H, o-H PhN), 6.99 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 7.05 (d, 140.4 (Cipso), 154.9 (C-O) ppm. C19H33NO (291.4): calcd. C 78.29,
JH,H = 8.4 Hz, 2 H, m-H PhN), 7.27 (d, JH,H = 2.4 Hz, 1 H, m-H, H 11.41, N 4.81; found C 78.09, H 11.79, N 4.62.
PhOH), 8.71 (s, 1 H, OH) ppm. C22H31NO (325.5): calcd. C 81.18,
N-(2,6-Me2C6H4)-[2,4-di-tert-butyl]benzo-1-oxa-3-azine (2e1):
A
H 9.60, N 4.30; found C 80.97, H 9.82, N 4.45.
procedure similar to that described for 2d1 but with the use of a
suspension of paraformaldehyde (4.15 g, 138.7 mmol), 2,4-di-tert-
butylphenol (28.21 g, 136.26 mmol) and 2,6-dimethylaniline
(16.8 mL, 136.7 mmol) in MeOH (250 mL) gave 2e1 obtained as an
CyN(H)CH2(3,5-tBu2C6H2-2-OH) (2c): A procedure similar to that
described for 2a but with the use of 1c (15.76 g, 50 mmol) and
NaBH4 (2.36 g, 55 mmol) in thf (150 mL) gave 2c (13.54 g,
42.6 mmol, 85% yield). 1H NMR (300 MHz, CDCl3): δ = 1.07–
1.91 (m, 11 H, cyclohexyl-H), 1.22 [s, 9 H, C(CH3)3], 1.40 [s, 9 H,
1
analytically pure pale-yellow solid (10.06 g, 21% yield). H NMR
(300 MHz, C6D6): δ = 1.32 [s, 9 H, C(CH3)3-phenol], 1.59 [s, 9 H,
C(CH3)3-phenol], 2.14 [s, 6 H, 2 CH3-(2,6-Me2phenyl)], 4.10 (s, 2
C(CH3)3], 2.52 (br., 1 H, NH), 3.95 (s, 2 H, CH2), 6.85 (d, JH,H
=
4
H, N-CH2-benzene), 4.68 (s, 2 H, O-CH2-N), 6.85 (d, J = 2.1 Hz,
2.4 Hz, 1 H, m-H, PhOH), 7.20 (d, JH,H = 2.4 Hz, 1 H, m-H,
PhOH) ppm; resonances for the OH protons not observed.
C21H35NO (317.3): calcd. C 79.44, H 11.11, N 4.41; found C 79.32,
H 11.35, N 4.32.
1 H, CH-benzoxazine), 7.11 (d, 4J = 2.4 Hz, 1 H, CH-benzoxazine),
6.93 and 7.01 [m, 3 H, 3 CH-(2,6-Me2phenyl)] ppm. C24H33NO
(351.5): calcd. C 82.00, H 9.46, N 3.98; found C 82.04, H 9.99, N
3.59.
N-tert-Butyl-[2,4-di-tert-butyl]benzo-1-oxa-3-azine (2d1): A suspen-
sion of paraformaldehyde (4.15 g, 138.7 mmol), 2,4-di-tert-bu-
tylphenol (28.21 g, 136.26 mmol) and freshly purified tert-bu-
tylamine (10.00 g, 136.7 mmol) in MeOH (250 mL) was heated at
refluxed with vigorous stirring and at atmospheric pressure for 4 d.
The solution was cooled to room temperature and the solvent was
distilled off under reduced pressure. The title compound, which
solidifies on standing, was manually isolated from the resulting
crude oil (17.1 g as a 1:1 molar ratio mixture by 1H NMR). N-
tBu-[2,4-di-tert-butyl]benzo-1-oxa-3-azine 2d1 was obtained as an
analytically pure pale yellow solid (8.1 g, 26.7 mmol, 21% yield
based on starting 2,4-di-tert-butylphenol). M.p. 155 °C (decomp.).
(2,6-Me2C6H3)N(H)CH2(3,5-tBu2C6H2-2-OH) (2e): A solution of
AlLiH4 (1  in ethyl ether, 50 mL, 50 mmol) was added under vig-
orous stirring to a 0 °C solution containing 1e (2.36 g, 55 mmol) in
thf (150 mL). The reaction mixture was stirred for 12 h resulting in
a white suspension to which a saturated solution of NH4Cl in water
(30 mL) was added. The resulting mixture was completely evapo-
rated under reduced pressure, and the solid residue obtained was
extracted with ethyl ether (3ϫ100 mL). The organic layer was iso-
lated by filtration, dried with Na2SO4 and filtered again, and the
volatiles were completely removed under reduced pressure. The
white solid obtained was poured into methanol (30 mL) and stirred
for 2 h and then cooled to –40 °C for 1 h. After removal of the
solvent by filtration and complete drying under reduced pressure,
a solid was isolated and characterised as 2e (15.76 g, 47.0 mmol,
93% yield). 1H NMR (300 MHz, CDCl3): δ = 1.21 [s, 9 H,
C(CH3)3], 1.31 [s, 9 H, C(CH3)3], 2.42 [s, 6 H, 2 CH3-(2,6-Me2-
Rf = 0.5562 (silica gel; hexane/acetone, 95:5). FTIR (KBr pellets):
1
ν = 2983, 2923, 1238 cm–1. H NMR (300 MHz, CDCl ): δ = 1.22
˜
3
[s, 9 H, N-C(CH3)3], 1.29 [s, 9 H, C(CH3)-phenol], 1.37 [s, 9 H,
C(CH3)-phenol], 4.13 (s, 2 H, N-CH2-benzene), 4.96 (s, 2 H, O-
4
CH2-N), 6.85 (AB spin system, J = 2.1 Hz, 1 H, CH-arom), 7.11
phenyl)], 3.50 (br., 1 H, NH), 4.14 (s, 2 H, CH2), 6.95 (d, JH,H
=
(AB spin system, 4J = 2.4 Hz, 1 H, CH-arom) ppm. 13C{1H}NMR
(75 MHz, CDCl3): δ = 28.2 [C(CH3)], 29.7 [C(CH3)], 31.7 [C(CH3)],
34.3 [C(CH3)], 34.8 [C(CH3)], 46.0 (N-CH2-benzene), 54.3 [N-
C(CH3)], 78.2 (O-CH2-N), 121.0 (CH-arom), 121.3 (CH-arom),
122.1 (Cipso), 136.7 (Cipso), 141.9 (Cipso), 151.7 (C-O) ppm.
C20H33NO (303.4): calcd. C 79.15, H 10.96, N 4.62; found C 79.04,
H 10.99, N 4.59.
2.4 Hz, 1 H, m-H, PhOH), 6.97–7.07 (m, 3 H, PhN), 7.32 (d, JH,H
1
= 2.4 Hz, 1 H, m-H, PhOH), 10.27 (br., 1 H, OH) ppm. H NMR
(300 MHz, C6D6): δ = 1.37 [s, 9 H, C(CH3)3], 1.77 [s, 9 H, C(CH3)
3], 1.98 [s, 6 H, 2 CH3-(2,6-Me2phenyl)], 2.97 (t, JH,H = 8.1 Hz, 1
H, NH), 3.73 (d, JH,H = 8.1 Hz, 2 H, CH2), 6.83 (s, 3 H, PhN),
6.89 (d, JH,H = 2.4 Hz, 1 H, m-H, PhOH), 7.55 (d, JH,H = 2.4 Hz,
1 H, m-H, PhOH), 10.53 (s, 1 H, OH) ppm. C23H33NO (337.5):
calcd. C 81.37, H 9.80, N 4.71; found C 81.54, H 9.61, N 4.59.
tBuN(H)CH2(3,5-tBu2C6H2-2-OH) (2d): Benz-1-oxa-3-azine (2d1;
40.85 g, 134.61 mmol) was dissolved in EtOH (950 mL) with stir-
ring. The solution was stirred vigorously at room temperature for
2 d. A fine precipitate appeared over this time, and the solution
was decanted for 5 d. The pale-yellow solid was isolated by fil-
tration through a fritted funnel and washed with EtOH (2ϫ). The
compound obtained (8.40 g) was recrystallised from EtOH at
–10 °C and isolated as off-white needles after filtration, washing
with cold EtOH and then suction by means of a water vacuum
aspirator. It was further dried at room temperature under reduced
pressure for 24 h to constant weight yielding 2d as off-white needles
(8.24 g, 28.2 mmol, 20% yield). M.p. 89 °C (decomp.). Rf = 0.4312
(p-MeC6H4)N(H)CH2(C6H4-2-OH) (2f): A procedure similar to
that described for 2a but with the use of a 1f (15.76 g, 50 mmol)
and NaBH4 (2.36 g, 55 mmol) in thf (150 mL) gave 2f (9.92 g,
1
46.5 mmol, 93% yield). H NMR (300 MHz, CDCl3): δ = 2.06 (s,
3 H, CH3), 3.80 (s, 2 H, CH2), 6.75 (d, JH,H = 8.1 Hz, 2 H, o-H,
PhN), 6.83–6.88 (m, 2 H, PhO), 7.04 (d, JH,H = 8.1 Hz, 2 H, m-H,
PhN), 7.11–7.23 (m, 2 H, PhO), 8.62 (br., 1 H, OH) ppm. 1H NMR
(300 MHz, C6D6): δ = 2.08 (s, 3 H, CH3), 2.86 (br., 1 H, NH), 3.80
(s, 2 H, CH2), 6.36 (d, JH,H = 8.1 Hz, 2 H, o-H, PhN), 6.73–7.10
(m, 6 H, PhO, PhN), 8.67 (br., 1 H, OH) ppm. C14H15NO (213.3):
calcd. C 78.84, H 7.09, N 6.57; found C 78.69, H 6.92, N 6.43.
(silica gel; hexane/acetone, 95:5). FTIR (KBr pellets): ν = 2963,
˜
tBuN(Me)CH2(3,5-tBu2C6H2-2-OH) (2g)
2866, 1251 cm–1. 1H NMR (300 MHz, CDCl3): δ = 1.20 [s, 9 H,
N-C(CH3)3], 1.27 [s, 9 H, C(CH3)3-phenol], 1.41 [s, 9 H, C(CH3)3-
Method 1: Benzoxazine 2d1 (1.38 g, 4.54 mmol) was dissolved un-
4
phenol], 3.89 (s, 2 H, CH2), 6.88 (d, J = 2.4 Hz, 1 H, CH), 7.20 der argon in ethanol (20 mL) and NaBH4 (858 mg, 22.70 mmol)
(d, 4J = 2.7 Hz, 1 H, CH) ppm. Signals of OH and NH are ob-
was added in one portion under vigorous stirring. The solution was
stirred for 2 d under argon with vigorous stirring. The solvent was
1
scured by the baseline. H NMR (300 MHz, C6D6): δ = 0.76 [s, 9
Eur. J. Inorg. Chem. 2008, 4638–4649
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4645

G. Alesso, M. Sanz, M. E. G. Mosquera, T. Cuenca
FULL PAPER
then completely removed, and the residue was dissolved in CH2Cl2,
and then, poured into a saturated solution of NH4Cl in water. The
organic layer was separated, repetitively washed with water and a
saturated solution of NaCl in water and further separated. The
organic phase was dried with MgSO4 and filtered. After complete
removal of volatiles, the crude yellow oil (1.39 g), which solidifies
on standing, was purified by flash column chromatography (silica
gel; n-hexane/acetone, 95:5). The solvent was distilled off under re-
duced pressure to give 2g as a pale yellow oil (1.28 g, 4.19 mmol,
92% yield) that solidifies also on standing.
[s, 9 H, N-C(CH3)3], 1.23 (m, 2 H, N-CH2-CH2-CH3), 1.27 [s, 9 H,
C(CH3)3-phenol], 1.41 [s, 9 H, C(CH3)3-phenol], 2.61 (m, 2 H, N-
CH2CH2CH3), 3.78 (s, 2 H, N-CH2-phenol), 5.24 (s, 1 H, OH),
6.75 (d, J = 2.4 Hz, 1 H, CH-phenol), 7.13 (d, J = 2.4 Hz, 1 H,
CH-phenol) ppm. C22H39NO (333.5): calcd. C 79.22, H 11.78, N
4.20; found C 79.38, H 11.59, N 4.13.
4
4
tBuN(CH2Ph)CH2(3,5-tBu2C6H2-2-OH) (2j): A solution of LiPh
(1.8  in cyclohexane/ethyl ether, 0.95 mL, 1.71 mmol) dissolved in
thf was added dropwise under vigorous stirring to a solution of
2d1 (130 mg, 0.42 mmol) in ethyl ether (or thf) (30 mL) cooled un-
der argon at –78 or 0 °C. The solution was gradually warmed to
room temperature, and vigorously stirred for 2 h under. The solu-
tion was poured into a saturated solution of NH4Cl in water. The
organic layer was separated, repetitively washed with water and a
saturated solution of NaCl in water and further separated. The
organic phase was dried with MgSO4 and filtered. The solvent was
completely removed under reduced pressure to give the correspond-
ing crude substance (157 mg), which was purified by flash column
chromatography (silica gel; n-hexane/acetone, 95:5). Product 2j was
obtained as an analytically pure yellow oil (116 mg, 0.30 mmol,
72% yield) after complete removal of volatiles. Rf = 0.5012 (silica
Method 2:
A suspension of 2,4-di-tert-butylphenol (2.37 g,
11.49 mmol), N-tert-butyl-methylamine (1.00 g, 11.57 mmol) and
paraformaldehyde (376 mg, 12.53 mmol) in methanol (50 mL) was
heated at reflux for 2 d. A crude brownish oil (3.13 g) was isolated
by complete removal of the volatiles under reduced pressure, and it
was purified by flash column chromatography (silica gel; n-hexane/
acetone, 70:30). Product 2g was obtained as an analytically pure
yellow oil (2.92 g, 9.5 mmol, 83% yield) after completely removing
the volatiles. Rf = 0.7812 (silica gel; hexane/acetone, 70:30). 1H
NMR (300 MHz, CDCl3): δ = 1.22 [s, 9 H, N-C(CH3)3], 1.30 [s, 9
H, C(CH3)3-benzene], 1.43 [s, 9 H, C(CH3)3-benzene], 2.23 (s, 3 H,
N-CH3), 3.91 (s, 2 H, CH2), 4.64 (s, 1 H, OH), 6.81 (d, 4J = 2.4 Hz,
1 H, CH), 7.19 (d, 4J = 2.4 Hz, 1 H, CH) ppm. C20H35NO (305.5):
calcd. C 78.29, H 11.41, N 4.81; found C 78.63, H 11.55, N 4.58.
1
gel; hexane/acetone, 95:5). H NMR (300 MHz, CDCl3): δ = 1.20
[s, 9 H, N-C(CH3)3], 1.27 [s, 9 H, C(CH3)3-phenol], 1.41 [s, 9 H,
C(CH3)3-phenol], 4.38 (dt, J = 3.9, 13.6 Hz, 4 H, Phenol-CH2, N-
CH2-C6H5), 7.60–7.17 (m, 7 H, 2 CH-phenol, C6H5-CH2-N) ppm.
C26H39NO (381.6): calcd. C 81.84, H 10.30, N 3.67; found C 81.86,
H 10.21, N 3.78.
tBuN(Et)CH2(3,5-tBu2C6H2-2-OH) (2h): A solution of LiMe (1.6 
in ethyl ether, 1.6 mL, 2.24 mmol) or a solution of MgClMe (3 
in thf, 0.74 mL, 2.24 mmol) was added dropwise under vigorous
stirring to a solution of 2d1 (170 mg, 0.56 mmol) in ethyl ether (or
thf) (30 mL) cooled under argon at –78 or 0 °C. The solution was
gradually warmed to room temperature, and vigorously stirred for
2 h. The solution was poured into a saturated solution of NH4Cl
in water. The organic layer was separated, repetitively washed with
water and a saturated solution of NaCl in water and further sepa-
rated. The organic phase was dried with MgSO4 and filtered. The
solvent was completely removed under reduced pressure to give the
corresponding crude substance (169 mg), which was purified by
flash column chromatography (silica gel; n-hexane/acetone, 95:5).
Product 2h was obtained as an analytically pure yellow oil (148 mg,
0.46 mmol, 83% yield) after complete removal of volatiles. Rf =
0.5225 (silica gel; hexane/acetone, 95:5). 1H NMR (300 MHz,
Ti(η5-C5H5)[PhNCH2(3,5-tBu2C6H2-2-O)]Cl (3a): A solution of 2a
(311.5 mg, 1 mmol) and NEt3 (0.35 mL, 2.5 mmol) in pentane
(50 mL) was added under vigorous stirring to Ti(η5-C5H5)Cl3
(219.3 mg, 1 mmol). After 12 h the solution appeared brown with
the formation of HCl·NEt3 as a white precipitate. The solution was
filtered off and the solvent evaporated to give a solid, which was
recrystallised from toluene at –30 °C and characterised as 3a
(413.1 mg, 0.90 mmol, 90% yield). 1H NMR (300 MHz, CDCl3): δ
= 1.28 [s, 9 H, C(CH3)3], 1.38 [s, 9 H, C(CH3)3], 4.45 and 6.06 (AB
1
system, JA,B = 16.5 Hz, 2 H, CH2), 6.42 (s, 5 H, Cp), 6.83 (dd, J
= 8.4 Hz, 2J = 0.9 Hz, 2 H, o-H PhN), 7.08 (d, JH,H = 2.4 Hz, 1 H,
PhO), 7.12–7.32 (m, 3 H, PhN) ppm. 1H NMR (300 MHz, C6D6): δ
= 1.28 [s, 9 H, C(CH3)3], 1.46 [s, 9 H, C(CH3)3], 4.18 and 6.07 (AB
1
system, JA,B = 16.5 Hz, 2 H, CH2), 6.15 (s, 5 H, Cp), 6.69 (dd, J
3
CDCl3): δ = 0.99 (t, J = 7.2 Hz, 3 H, CH2-CH3), 1.21 [s, 9 H, N-
2
= 8.4 Hz, J = 1.2 Hz, 2 H, o-H PhN), 6.88 (t, p-H PhN, JH,H
=
C(CH3)3], 1.27 [s, 9 H, C(CH3)3-phenol], 1.42 [s, 9 H, C(CH3)3-
phenol], 2.64 (m, 2 H, N-CH2CH3), 3.84 (s, 2 H, N-CH2-phenol),
7.5 Hz, 1 H, 7.08), 6.93 (d, JH,H = 2.4 Hz, 1 H, PhO), 7.00 (t, JH,H
= 7.2 Hz, 2 H, m-H PhN), 7.39 (d, JH,H = 2.4 Hz, 1 H, PhO) ppm.
C26H32ClNOTi (457.9): calcd. C 68.20, H 7.04, N 3.06; found C
68.84, H 7.56, N 2.89.
4
5.11 (s, 1 H, OH), 6.79 (d, J = 2.4 Hz, 1 H, CH-phenol), 7.15 (d,
4J = 2.2 Hz, 1 H, CH-phenol) ppm. C21H37NO (319.5): calcd. C
78.94, H 11.67, N 4.38; found C 78.87, H 11.55, N 4.58.
Ti(η5-C5H5)[(4-MeC6H4)NCH2(3,5-tBu2C6H2-2-O)]Cl (3b):
A
tBuN(nPr)CH2(3,5-tBu2C6H2-2-OH) (2i): A solution of MgClEt
(2  in ethyl ether, 0.98 mL, 1.96 mmol) was added dropwise under
vigorous stirring to a solution of 2d1 (150 mg, 0.49 mmol) in ethyl
ether (or thf) (30 mL) cooled under argon at –78 or 0 °C. The solu-
tion was gradually warmed to room temperature, and vigorously
stirred for 2 h. The solution was poured into a saturated solution
of NH4Cl in water. The organic layer was separated, repetitively
washed with water and a saturated solution of NaCl in water and
further separated. The organic phase was dried with MgSO4 and
filtered. The solvent was completely removed under reduced pres-
sure to give the corresponding crude substance (134 mg), which
was purified by flash column chromatography (silica gel; n-hexane/
acetone, 95:5). Product 2i was obtained as an analytically pure yel-
low oil (128 mg, 0.38 mmol, 78% yield) after complete removal of
solution of 2b (325.5 mg, 1 mmol) and NEt3 (0.35 mL, 2.5 mmol)
in pentane (50 mL) was added under vigorous stirring to Ti(η5-
C5H5)Cl3 (219.3 mg, 1 mmol). After 12 h the solution appeared
brown with the formation of HCl·NEt3 as a white precipitate. The
solution was filtered off and the solvent evaporated to give a solid,
which was recrystallised from toluene at –30 °C and characterised
as 3b (413.6 mg, 0.87 mmol, 87% yield). 1H NMR (300 MHz,
C6D6): δ = 1.30 [s, 9 H, C(CH3)3], 1.50 [s, 9 H, C(CH3)3], 2.06 (s,
3 H, CH3), 4.20 and 6.21 (AB system, JA,B = 16.5 Hz, 2 H, CH2),
6.19 (s, 5 H, Cp), 6.64 (d, 1J1 = 8.4 Hz, 2 H, o-H PhN), 6.81 (t,
JH,H = 8.4 Hz, 2 H, m-H PhN), 6.96 (d, JH,H = 2.4 Hz, 1 H, PhO),
7.45 (d, JH,H = 2.4 Hz, 1 H, PhO) ppm. C27H34ClNOTi (471.9):
calcd. C 68.72, H 7.26, N 2.97; found C 69.57, H 8.03, N 2.51.
volatiles. Rf = 0.5402 (silica gel; hexane/acetone, 95:5). 1H NMR Ti(η5-C5H5)[CyNCH2(3,5-tBu2C6H2-2-O)]Cl (3c): A solution of 2c
3
(300 MHz, CDCl3): δ = 0.90 (t, J = 7.1 Hz, 3 H, CH2-CH3), 1.21
(317.3 mg, 1 mmol) and NEt3 (0.35 mL, 2.5 mmol) in pentane
4646
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4638–4649

Monocyclopentadienyl Phenoxido–Amino and –Amido Ti Complexes
(50 mL) was added under vigorous stirring to Ti(η5-C5H5)Cl3
(219.3 mg, 1 mmol). After 12 h the solution appeared brown with
the formation of HCl·NEt3 as a white precipitate. The solution was
filtered off and concentrated until a yellow precipitate appeared
and then maintained at –40 °C for 12 h to give a solid, which was
recrystallised from toluene at –30 °C and characterised as 3c
under vigorous stirring to Ti(η5-C5H5)Cl3 (219.3 mg, 1 mmol). Af-
ter 3 h the solution appeared brown with the formation of
HCl·NEt3 as a white precipitate. The solution was filtered off and
the solvent evaporated to give a solid, which was recrystallised from
toluene at –30 °C and characterised as 5·HCl (501.6 mg,
0.98 mmol, 98% yield). H NMR (300 MHz, C6D6): δ = 1.33 [s, 9
H, C(CH3)3], 1.36 [s, 9 H, C(CH3)3], 1.39 [s, 9 H, C(CH3)3], 4.30
(br., 2 H, CH2), 6.81 (s, 5 H, Cp), 7.37 (d, JH,H = 2.0 Hz, 1 H,
1
1
(356.2 mg, 0.77 mmol, 77% yield). H NMR (300 MHz, C6D6): δ
= 0.85–1.59 (m, 10 H; cyclohexyl), 1.32 [s, 9 H, C(CH3)3], 1.46 [s,
9 H, C(CH3)3], 4.25 (pt, 1 H, cyclohexyl), 6.28 (s, 5 H, Cp), 7.00 PhO), 8.06 (d, JH,H = 2.0 Hz, 1 H, PhO), 9.40 (br., 2 H, NH2Cl)
(d, JH,H = 2.4 Hz, 1 H, PhO), 7.34 (d, JH,H = 2.4 Hz, 1 H, PhO) ppm. C24H38Cl2NOTi (510.8): calcd. C 56.43, H 7.50, N 2.74;
ppm. C26H38ClNOTi (463.9): calcd. C 67.31, H 8.26, N 3.02; found
C 67.45, H 8.27, N 2.71.
found C 56.37, H 7.83, N 2.41.
Ti(η5-C5H5)[Ph(H)NCH2(3,5-tBu2C6H2-2-O)]Cl2 (6a): A solution
of 2a (311.5 mg, 1 mmol) and NEt3 (0.35 mL, 2.5 mmol) in toluene
(50 mL) was added under vigorous stirring to Ti(η5-C5H5)Cl3
(219.3 mg, 1 mmol). After 12 h the solution appeared red with the
formation of HCl·NEt3 as a white precipitated. The solution was
filtered off and concentrated to a volume of 10 mL and maintained
at –40 °C for 12 h to give a solid, which was recrystallised from
toluene at –30 °C and characterised as a 4:1 molar ratio mixture of
Ti(η5-C5H5)[tBuNCH2(3,5-tBu2C6H2-2-O)]Cl (3d): A solution of
NEt3 (0.35 mL, 2.5 mmol) in ethyl ether (50 mL) was added under
vigorous stirring to 5·HCl (510.8 mg, 1 mmol). After 7 d the solu-
tion appeared brown with the formation of HCl·NEt3 as a white
precipitate. The solution was filtered off and concentrated to a vol-
ume of ca. 10 mL and then maintained at –40 °C for 12 h to give
a solid, which was recrystallised from toluene at –30 °C and charac-
terised as 3d (326.4 mg, 0.74 mmol, 74% yield). 1H NMR
(300 MHz, C6D6): δ = 0.97 [s, 9 H, C(CH3)3], 1.36 [s, 9 H,
C(CH3)3], 1.54 [s, 9 H, C(CH3)3], 3.56 and 4.62 (AB system, JA,B
= 16.5 Hz, 2 H, CH2), 6.24 (s, 5 H, Cp), 7.12 (d, JH,H = 2.4 Hz, 1
H, PhO), 7.43 (d, JH,H = 2.4 Hz, 1 H, PhO) ppm. C24H36ClNOTi
(437.9): calcd. C 65.83, H 8.29, N 3.20; found C 66.03, H 8.12, N
3.38.
1
6a-1/6a-2 (336.1 mg, 0.68 mmol, 68% yield). H NMR (300 MHz,
C6D6, stereoisomer 6a-1): δ = 1.23 [s, 9 H, C(CH3)3], 1.56 [s, 9 H,
C(CH3)3], 3.24 (pt, J = 6.5 Hz, 1 H, NH, X of an ABX spin sys-
3
2
tem), 4.26 and 4.46 (pd, JA,X/B,X ≈ 6.5 Hz, JA,B = 4.5 Hz, 2 H,
1
CH2, AB of an ABX spin system), 6.39 (s, 5 H, Cp), 6.62 (dd, J
= 8.4 Hz, 2J = 1.2 Hz, 2 H, o-H PhN), 6.73 (t, JH,H = 7.2 Hz, 1 H,
p-H PhN), 7.19–7.22 (m, 3 H, arom.), 7.46 (d, JH,H = 2.4 Hz, 1 H,
PhO) ppm. 1H NMR (300 MHz, C6D6, stereoisomer 6a-2): δ = 1.27
[s, 9 H, C(CH3)3], 1.60 [s, 9 H, C(CH3)3], 3.71 (pt, JA,X = 6.7 Hz,
1 H, NH, X of an AAЈX spin system), 4.51 (pd, JA,X = 6.7 Hz, 2
H, CH2, AAЈ of an AAЈX spin system), 6.32 (s, 5 H, Cp), 6.44–
7.48 (m, 7 H, Ph), 7.46 (d, JH,H = 2.4 Hz, 1 H, PhO) ppm.
C26H33Cl2NOTi (494.3): calcd. C 63.17, H 6.73, N 2.83; found C
63.54, H 7.91, N 2.65.
Ti(η5-C5H4SiMe2Cl)[PhNCH2(3,5-tBu2C6H2-2-O)]Cl (4a): A solu-
tion of 2a (311.5 mg, 1 mmol) and NEt3 (0.35 mL, 2.5 mmol) in
pentane (50 mL) was added under vigorous stirring to Ti(η5-
C5H4SiMe2Cl)Cl3 (311.9 mg, 1 mmol). After 12 h the solution ap-
peared brown with the formation of HCl·NEt3 as a white precipi-
tate. The solution was filtered off and the solvent evaporated to
give a solid, which was recrystallised from toluene at –30 °C and
characterised as 4a (413.1 mg, 0.93 mmol, 93% yield). 1H NMR
(300 MHz, C6D6): δ = 0.73 (s, 3 H, Si-CH3), 0.79 (s, 3 H, Si-CH3),
1.27 [s, 9 H, C(CH3)3], 1.50 [s, 9 H, C(CH3)3], 4.23 and 5.99 (AB
system, JA,B = 16.2 Hz, 2 H, CH2), 6.17 and 6.53 (m, 4 H, ABCD
Polymerisation Procedure: Toluene (50 mL) was introduced under
argon into the Schlenk reactor equipped with a magnetic stirrer
and maintained at the desired temperature using external thermal
control with vigorous stirring for 30 min. sMAO was then injected
and the mixture stirred for 15 min. The argon was replaced by eth-
ylene by degassing the solution under vacuum and refilling with
the olefin. This procedure was repeated and the solution was finally
saturated with the olefin for 15 min. As soon as the titanium com-
plex was injected to the mixture, polymerisation time was counted.
The polymerisation was terminated by methanol injection. The
polymer was precipitated with a solution of HCl (5% in MeOH,
100 mL), stirred, filtered and washed successively with of a solution
of HCl (5% in MeOH, 50 mL), water (100 mL) and MeOH
(100 mL). The polymer was finally dried under vacuum at 50 °C
for 24 h to constant weight.
1
2
system, C5H4), 6.22 (dd, JH,H = 7.2 Hz, JH,H = 1.2 Hz, 2 H, o-H
1
PhN), 6.86 (d, JH,H = 2.4 Hz, 1 H, m-H, PhO), 6.88 (dd, JH,H
=
2
7.8 Hz, JH,H = 1.2 Hz, 1 H, p-H PhN), 6.97 (t, JH,H = 8.7 Hz, 2
H, m-H PhN), 7.43 (d, JH,H = 2.4 Hz, 1 H, m-H, PhO) ppm.
13C{1H} NMR (75 MHz, C6D6): δ = 3.1 and 3.2 [Si(CH3)2], 30.1
[C(CH3)3], 32.1 [C(CH3)3], 35.1 [C(CH3)3], 35.7 [C(CH3)3], 64.5
(CH2), 119.4–144.8 (C5H4 and arom.), 159.8 (Cipso-PhO), 161.4
(Cipso-PhN) ppm. C28H37Cl2NOSiTi (540.5): calcd. C 61.09, H
6.78, N 2.54; found C 61.53, H 7.14, N 2.29.
Ti(η5-C5H5)[tBu(H)NCH2(3,5-tBu2C6H2-2-O)]Cl2 (5): A solution
of 2d (291.5 mg, 1 mmol) and NEt3 (0.35 mL, 2.5 mmol) in pentane
(50 mL) was added under vigorous stirring to Ti(η5-C5H5)Cl3
(219.3 mg, 1 mmol). After 12 h the solution appeared brown with
the formation of HCl·NEt3 as a white precipitate. The solution was
filtered off and concentrated to a volume of ca. 10 mL and then
maintained at –40 °C for 12 h to give a solid, which was recrystal-
lised from toluene at –40 °C and characterised as 5 (251.6 mg,
Single-Crystal X-ray Structure Determination of Compounds 2a, 2d,
2e and 3d: Suitable single crystals of 2a, 2d, 2e and 3d for the X-
ray diffraction study were selected. For compound 2e data collec-
tion was carried out at 298 K, whereas data collection for 2a, 2d
and 3d was performed at 200(2) K, with the crystals covered with
perfluorinated ether for 2a, 2d and 3d. The crystals were mounted
on a Bruker-Nonius Kappa CCD single crystal diffractometer
equipped with a graphite-monochromated Mo-Kα radiation (λ =
0.71073 Å). Multiscan[43] absorption correction procedures were
applied to the data. The structures were solved by using the
WINGX package,[44] by direct methods (SHELXS-97) and refined
by using full-matrix least-squares against F2 (SHELXL-97).[45] All
1
0.53 mmol, 53% yield). H NMR (300 MHz, C6D6): δ = 1.15 [s, 9
H, C(CH3)3], 1.36 [s, 9 H, C(CH3)3], 1.52 [s, 9 H, C(CH3)3], 3.87
(br., 2 H, CH2), 6.30 (s, 5 H, Cp), 7.23 (d, JH,H = 2.0 Hz, 1 H,
PhO), 7.42 (d, JH,H = 2.0 Hz, 1 H, PhO), 7.65 (br., 1 H, NH) ppm.
C24H37Cl2NOTi (474.3): calcd. C 60.77, H 7.86, N 2.95; found C
60.32, H 8.34, N 2.93.
Ti(η5-C5H5)[tBu(H)NCH2(3,5-tBu2C6H2-2-O)]Cl2·HCl (5·HCl): A non-hydrogen atoms were anisotropically refined except for the car-
solution of 2d (291.5 mg, 1 mmol) in ethyl ether (50 mL) was added bon atoms in the Cp ring for 3d that were disorder in two positions.
Eur. J. Inorg. Chem. 2008, 4638–4649
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4647

G. Alesso, M. Sanz, M. E. G. Mosquera, T. Cuenca
FULL PAPER
Table 2. Crystal data and structure refinement details for 2a, 2d, 2e and 3d.
2a
2d
2e
3d
Formula
Fw
C21H29NO
311.45
C19H33NO
291.46
C23H33NO
339.50
C24H36NOClTi
437.89
Colour/habit
Crystal dimensions [mm]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
white/prism
0.44ϫ0.37ϫ0.23
orthorhombic
P212121
8.5031(7)
12.582(3)
17.859(4)
90
white/prism
0.44ϫ0.17ϫ0.12
monoclinic
P21/n
white/prism
0.41ϫ0.27ϫ0.24
monoclinic
Cc
8.556(3)
32.851(13)
7.687(6)
95.75(5)
2150(2)
dark red/prism
0.59ϫ0.34ϫ0.29
monoclinic
P21/a
13.742(2)
10.2730(12)
17.477(2)
96.354(11)
2452.1(5)
4
5.940(3)
18.755(3)
16.371(4)
94.96(2)
1816.9(11)
4
β [°]
V [Å3]
1910.7(6)
4
Z
4
T [K]
200
1.083
0.065
200
1.066
0.064
298
1.049
0.063
200
1.186
0.471
ρcalcd. [gcm–3]
µ [mm–1]
F(000)
θ range [°]
680
3.68–25.02
19096
1927/0.0984
1486
1927/0/216
0.0429/0.0965
0.0667/0.1075
648
3.31–27.50
35106
4165/0.1098
2415
4165/168/221
0.0630/0.1417
0.1251/0.1659
0.010(2)
744
3.03–27.59
8101
2473/0.0610
1737
2473/2/247
0.0496/0.1133
0.0832/0.1322
936
3.03–27.51
19557
5637/0.0645
4027
5637/0/248
0.0479/0.1041
0.0795/0.1182
No. of rflns. collected
No. of indep. rflns./Rint
No. of obsd. rflns. [IϾ2σ(I)]
No. of data/restraints/params.
R1/wR2 [IϾ2σ(I)]
R1/wR2 (all data)
Extinction coefficient
GOF (on F2)
Largest diff peak/hole [eÅ–3]
1.045
+0.153/–0.152
1.063
0.273 and –0.239
1.022
+0.145/–0.161
1.029
+0.432/–0.383
[2]
J. Saito, M. Mitani, J. Mohri, Y. Yoshida, S. Matsui, S. Ishii,
S. Kojoh, N. Kashiwa, T. Fujita, Angew. Chem. Int. Ed. 2001,
40, 2918–2920.
Y. Suzuki, H. Terao, T. Fujita, Bull. Chem. Soc. Jpn. 2003, 76,
1493–1517.
Y. Tohi, H. Makio, S. Matsui, M. Onda, T. Fujita, Macromole-
cules 2003, 36, 523–525.
Y. Yoshida, J. Mohri, S. Ishii, M. Mitani, J. Saito, S. Matsui,
H. Makio, T. Nakano, H. Tanaka, M. Onda, Y. Yamamoto,
A. Mizuno, T. Fujita, J. Am. Chem. Soc. 2004, 126, 12023–
12032.
As well N1 and C10 in compound 2d show some disorder that was
treated. For 2d DELU and SIMU restrains were applied. Hydrogen
atoms were geometrically placed and left riding on their parent
atoms except for the hydrogen atoms on: O1, N1 in compounds 2a,
2d, 2e; N1Ј in compound 2dЈ and C13, C14, C15 in 2a. Compound
2d crystallises as the racemic mixture of the two enantiomers. Com-
pounds 2a and 2e are chiral and crystallised in noncentrosymmetric
space groups (P212121 and Cc respectively). However, the Flack
parameter could not be reliably determined because of insufficient
anomalous scattering effects. Full-matrix least-squares refinements
were carried out by minimizing Σw(Fo – Fc ) with the SHELXL-
97 weighting scheme and stopped at shift/err Ͻ 0.001. The final
residual electron density maps showed no remarkable features. Rel-
evant crystallographic data and details of the refinements for the
four structures are given in Table 2.
[3]
[4]
[5]
2
2 2
[6]
[7]
[8]
J. Saito, Y. Tohi, N. Matsukawa, M. Mitani, T. Fujita, Macro-
molecules 2005, 38, 4955–4957.
J. Saito, Y. Suzuki, H. Makio, H. Tanaka, M. Onda, T. Fujita,
Macromolecules 2006, 39, 4023–4031.
H. Terao, S. I. Ishii, J. Saito, S. Matsuura, M. Mitani, N. Na-
gai, H. Tanaka, T. Fujita, Macromolecules 2006, 39, 8584–
8593.
A. Sakuma, M. S. Weiser, T. Fujita, Polym. J. 2007, 39, 193–
207.
M. González-Maupoey, T. Cuenca, L. M. Frutos, O. Castano,
E. Herdtweck, Organometallics 2003, 22, 2694–2704.
M. González-Maupoey, T. Cuenca, Organometallics 2006, 25,
4358–4365.
M. González-Maupoey, T. Cuenca, L. M. Frutos, O. Castaño,
E. Herdtweck, B. Rieger, Eur. J. Inorg. Chem. 2007, 147–161.
V. Tabernero, T. Cuenca, E. Herdtweck, Eur. J. Inorg. Chem.
2004, 3154–3162.
V. Tabernero, C. Maestre, G. Jiménez, T. Cuenca, C. R. de Ar-
ellano, Organometallics 2006, 25, 1723–1727.
V. Tabernero, T. Cuenca, Eur. J. Inorg. Chem. 2005, 338–346.
S. Matsui, M. Mitani, J. Saito, Y. Tohi, H. Makio, N. Matsu-
kawa, Y. Takagi, K. Tsuru, M. Nitabaru, T. Nakano, H.
Tanaka, N. Kashiwa, T. Fujita, J. Am. Chem. Soc. 2001, 123,
6847–6856.
CCDC-686502 (for 2a), -686503 (for 2d), -686504 (for 2e) and
-686505 (for 3d) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
[9]
[10]
[11]
[12]
[13]
[14]
Acknowledgments
Financial support for this research by Dirección General de In-
vestigación Científica y Técnica (Project MAT2007-60997), Com-
unidad Autónoma de Madrid (Project S-0505-PPQ/0328-02) and
by the European Commission (Contract Nr. HPRN-CT2000-
00004) is gratefully acknowledged.
[15]
[16]
[1] L. Resconi, J. C. Chadwick, L. Cavallo, Comprehensive Organo-
metallic Chemistry III (Eds.: M. P. Mingos, R. H. Crabtree),
Elsevier, London, 2006, vol. 4, ch. 9.
4648
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4638–4649

Monocyclopentadienyl Phenoxido–Amino and –Amido Ti Complexes
[17]
[31] R. M. Pupi, J. N. Coalter, J. L. Petersen, J. Organomet. Chem.
1995, 497, 17–25.
[32] M. F. Lappert, P. P. Power, A. R. Sanger, R. C. Srivastava,
Metal and Metalloid Amides (Ellis Horwood Series in Chemical
Science), John Wiley and Sons, New York, 1980.
[33] D. M. Giolando, K. Kirschbaum, L. J. Graves, U. Bolle, Inorg.
Chem. 1992, 31, 3887–3890.
[34] M. H. Chisholm, J. H. Huang, J. C. Huffman, W. E. Streib, D.
Tiedtke, Polyhedron 1997, 16, 2941–2949.
[35] S. Fokken, T. P. Spaniol, J. Okuda, F. G. Sernetz, R. Mulhaupt,
Organometallics 1997, 16, 4240–4242.
[36] I. Tritto, S. X. Li, M. C. Sacchi, G. Zannoni, Macromolecules
1993, 26, 7111–7115.
[37] I. Kim, R. F. Jordan, Macromolecules 1996, 29, 489–491.
[38] D. D. Perrin, W. L. F. Armarego, Purification of Laboratory
Chemicals, Pergamon, Oxford, 1988.
D. C. H. Oakes, B. S. Kimberley, V. C. Gibson, D. J. Jones,
A. J. P. White, D. J. Williams, Chem. Commun. 2004, 2174–
2175.
G. Palmieri, Tetrahedron: Asymmetry 2000, 11, 3361–3373.
K. G. Mizuch, Zh. Obshch. Khim. 1953, 23, 861–864.
H. Kapnang, G. Charles, Tetrahedron Lett. 1983, 24, 1597–
1600.
P. Q. Huang, S. Arseniyadis, H. P. Husson, Tetrahedron Lett.
1987, 28, 547–550.
L. F. Roa, D. Gnecco, A. Galindo, J. L. Teran, S. Bernes, Tetra-
hedron: Asymmetry 2004, 15, 847–850.
[18]
[19]
[20]
[21]
[22]
[23]
M. S. Hill, D. A. Atwood, Main Group Chem. 1998, 2, 285–
292.
[24] V. C. Gibson, B. S. Kimberley, Eur. Pat. Appl., EP 953571 A1,
1999.
[25] D. Kanamori, A. Furukawa, T. Okamura, H. Yamamoto, N. [39] R. D. Gorsich, J. Am. Chem. Soc. 1958, 80, 4744–4744.
Ueyama, Org. Biomol. Chem. 2005, 3, 1453–1459.
[26] M. C. Maestre, V. Tabernero, M. E. G. Mosquera, G. Jiménez,
T. Cuenca, Organometallics 2005, 24, 5853–5857.
[27] M. C. Maestre, C. Paniagua, E. Herdtweck, M. E. G. Mos-
quera, G. Jiménez, T. Cuenca, Organometallics 2007, 26, 4243–
4251.
[28] M. C. Maestre, M. E.G. Mosquera, H. Jacobsen, G. Jiménez,
T. Cuenca, Organometallics 2008, 27, in press.
[29] A. Van der Linden, C. J. Schaverien, N. Meijboom, C. Ganter,
A. G. Orpen, J. Am. Chem. Soc. 1995, 117, 3008–3021.
[30] A. G. Orpen, L. Brammer, F. H. Allen, O. Kennard, D. G. Wat-
son, R. Taylor, J. Chem. Soc., Dalton Trans. 1989, S1–S83.
[40] R. D. Gorsich, J. Am. Chem. Soc. 1960, 82, 4211–4214.
[41] S. Ciruelos, T. Cuenca, P. Gómez Sal, A. Manzanero, Organo-
metallics 1995, 14, 177–185.
[42] W. C. Still, M. Kahn, A. Mitra, J. Org. Chem. 1978, 43, 2923–
2925.
[43] SORTAV: R. H. Blessing, Acta Crystallogr., Sect. A 1995, 51,
33–38.
[44] L. J. Farrugia, J. Appl. Crystallogr. 1999, 32, 837–938.
[45] G. M. Sheldrick, SHELXL-97, University of Göttingen,
Göttingen, Germany, 1998.
Received: May 30, 2008
Published Online: August 29, 2008
Eur. J. Inorg. Chem. 2008, 4638–4649
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4649