Synthesis, stereochemistry, bonding and fluxionality of 2-(inden-3-yl)phenols and their cyclopentadienyl titanium derivatives

Article abstract of DOI:10.1039/b310415j

The phenolic reagents 2-(inden-3-yl)-4,6-di-tert-butylphenol (1) and its 2-methyl (2), 1,2-dimethyl (3), 2,4,7-trimethyl (4) and 1,2,4,7-tetramethyl (5) derivatives have been obtained. The solid-states structures of 2, 3 and 4 have been determined by X-ra

Full text of DOI:10.1039/b310415j

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Synthesis, stereochemistry, bonding and fluxionality of
2-(inden-3-yl)phenols and their cyclopentadienyl titanium
derivatives
Luke E. Turner,a Matthew G. Thorn,a R. D. Swartz II,a Robert W. Chesnut,b
Phillip E. Fanwicka and Ian P. Rothwell*a
a Purdue University, Department of Chemistry, 560 Oval Drive, West Lafayette, IN 47907-2038,
USA
b Department of Chemistry, Eastern Illinois University, 600 Lincoln Avenue, IL 61920.
E-mail: Rothwell@purdue.edu
Received 28th August 2003, Accepted 28th September 2003
First published as an Advance Article on the web 28th October 2003
The phenolic reagents 2-(inden-3-yl)-4,6-di-tert-butylphenol (1) and its 2-methyl (2), 1,2-dimethyl (3), 2,4,7-trimethyl
(4) and 1,2,4,7-tetramethyl (5) derivatives have been obtained. The solid-state structures of 2, 3 and 4 have been
determined by X-ray diffraction and torsion angles (between the vinyl group and phenoxy ring) of 57, 61 and 79Њ
measured. Both the (aR) and (aS) forms of the ligands are present in the solid state. Solution 1H NMR spectra show
that rotation about the indenyl–phenoxy bond is facile for 1 but introduction of the 2-methyl substituent leads to
restricted rotation on the NMR timescale. In the crystals of 3 analyzed, only the (aS,S) and (aR,R) forms were
present, with the 1-methyl group pointing away from the OH group. In the 1H and 13C NMR spectra of 3 and 5 there
are two, equal intensity sets of signals. Hence, both diastereoisomeric forms are present in equal concentrations in
solution and two sharp OH singlets are observed for 3 even at 130 ЊC in p-xylene-d10. Reaction of the phenols 1–4
with [CpTiCl3] in the presence of pyridine has previously generated the corresponding mono-aryloxides 7–10 with no
evidence of the de-protonation of the indenyl ring in these reactions. In all four compounds both the (aR) and (aS)
forms are present within the unit cells. Variable temperature NMR studies of 7 allow the barrier to inden-3-yl
rotation (enantiomer interconversion) to be estimated at 13.9(5) kcal molϪ1 (at 20 ЊC). In solution only one major
set of 1H and 13C NMR resonances were observed for 1,2-dimethyl derivative 9. Hence, it appears that replacement
of the phenolic proton by the much bulkier [CpTiCl2] unit destabilizes the (aS,R) and (aR,S) forms in solution.
Attempted de-protonation of the inden-3-yl ring in 7 by treatment with n-BuLi or MeLi did not lead to the
formation of chelate rings. Instead formation of a Ti() dinuclear compound 11 and dimethyl derivative 12 occurred.
The barrier to indenyl rotation in 12 can be estimated to be 13.4(5) kcal molϪ1 at Ϫ5 ЊC, slightly lower than that
measured for the dichloride 7. Reaction of [CpTiCl3] with the di-lithio (doubly deprotonated ligand) did lead to the
formation of a chelated indenyl-phenoxide derivative 13. In the solid state only the (pS,R) and (pR,S) forms were
observed (indenyl oriented towards the Cp group, and in solution only one set of 1H and 13C NMR signals were
observed indicating the presence of this single diastereoisomer. The bonding of the indenyl group and Cp ligands in
13 have been compared.
which is inherently chiral.8–10 In this initial full paper we report
Introduction
on the synthesis of a variety of these ligands as well as their
The initial development by Bercaw, Shapiro et al.1 of bridged
cyclopentadienyl-titanium derivatives.11 This study pays par-
amido-cyclopentadienyl ligands for early transition organo-
metallic chemistry has been followed by intense research
ticular attention to the stereochemistry and fluxionality of the
ligands as well as observed bonding modes to the metal
interest into these and related “constrained geometry” systems.2
center.12,13
This interest has been stimulated by the high activity of single
component olefin polymerization catalysts that can be gener-
Results and discussion
ated with such ligands. Although the amido linked systems
dominate the literature, some related alkoxo(aryloxo)-cyclo-
pentadienyl ligands have been developed and studied. In this
context we have begun an exploration of the chemistry associ-
ated with the ligand 2-(inden-3-yl)-4,6-di-tert-butylphenol 1.
This particular ligand architecture was chosen for a number of
reasons. Firstly a great deal of discussion has appeared in the
literature concerning the chemistry of indenyl ligands com-
pared to their cyclopentadienyl counterparts. The basis of the
so-called “indenyl effect”3 lies in the ease with which the ligand
can slip from an η5- to an η3-bonding mode, relieving electronic
saturation at the metal and spawning new reactivity patterns.4,5
Furthermore the indenyl group is an integral part of many
chiral ansa-metallocenes6 and bis(2-R-indenyl)metallocenes7
where the ligands control the morphology (and properties) of
generated polymers. Secondly this ligand is intriguing given the
fact that chelation to a metal center via CH bond activation will
generate a constrained geometry, indenyl-aryloxide system
Ligand synthesis and stereochemistry
The treatment of 2-bromo-4,6-di-tert-butyl phenol with two
equivalents of BunLi in diethyl ether leads to a solution of the
corresponding di-lithio species. Addition of 1-indanone to this
solution produces 2-(inden-3-yl)-4,6-di-tert-butylphenol 1 in
moderate yield (Scheme 1). A similar procedure has been used
to prepare 2-(1-naphthyl)-4,6-di-tert-butylphenol from tetra-
lone. Analysis of the crude reaction mixture by GC/MS
showed the presence of 2,4-di-tert-butyl phenol and unreacted
1-indanone as the major impurities. During one synthesis a few
large white crystals were obtained directly from the product
mixture and shown by X-ray diffraction to contain a 1 : 1
mixture of 2,4-di-tert-butyl phenol and an aldol conden-
sation product of 1-indanone (Scheme 1). The use of methyl
substituted 1-indanones has allowed the isolation of the corre-
sponding methyl substituted ligands 2–5 (Scheme 1). The
D a l t o n T r a n s . , 2 0 0 3 , 4 5 8 0 – 4 5 8 9
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
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Scheme 1
position of the methyl substituents was chosen to have an
The 1H NMR spectrum of 1 is consistent with the tautomer
impact on both the dynamics and inherent stereochemistry of
these phenols.
shown (Scheme 1), the indenyl ring protons appearing as a dis-
tinct doublet and triplet at δ 3.69 and 6.78 ppm, respectively.
Futhermore, cooling a toluene-d8 solution of 1 to Ϫ75 ЊC does
not lead to splitting of the diastereotopic methylene protons.
Hence, it appears that rotation about the phenoxy–indenyl
bond is rapid on the NMR timescale (although it has to be
recognized that there may not be a resolvable difference in
chemical shifts). Previous NMR studies of 2,6-di(1-naphthyl)-
phenol have shown the barrier to naphthyl rotation in this
molecule can be estimated as 18.0(5) kcal molϪ1 at 67 ЊC.16
Hence, rotation appears to be more facile for the indenyl group
(5-membered ring) compared to the naphthyl case. The intro-
duction of a methyl group into the 2-position of the indenyl
ring (2) does not lead to well resolved CH2 protons, but the
Any restricted rotation about the sp2–sp2 (phenoxy-indenyl)
bond in ligands 1–5 has important stereochemical conse-
quences. The solid-state structures of 2, 3 and 4 have been
determined by X-ray diffraction. An ORTEP view of the 1,2-
dimethyl compound 3 is shown in Fig. 1. In all three compounds
the indenyl and phenoxy rings are twisted (non-coplanar) with
torsion angles (between the vinyl group and phenoxy ring) of
57, 61 and 79Њ for 2–4, respectively. This geometry leads to
atropisomerism for the indenyl-phenoxide nucleus, a situation
commonly encountered for bi-aryl systems.14 The two enantio-
mers formed by restricted rotation about this bond (axial sym-
metry) are shown in Scheme 2. The assignment of the (aR) and
(aS) forms is based upon the Cahn–Ingold–Prelog rules applied
to bi-aryls.15 In the crystals of 2, 3 and 4 both enantiomers are
present. Hence, the structures were modeled with a disordered
OH group. The position of the hydroxy group also has an
impact upon the conformation adopted by the tert-butyl
groups. Typically, a disorder of two rotamers is present with
one of the methyl groups pointing either towards or away from
the indenyl group. An adjacent hydroxy group would be
expected to lead to a preference for the methyl away rotamer.
1
ambient H NMR spectrum of 4 (methyl groups in the 2- and
4-positions) does show a well resolved AB pattern, consistent
with a significant barrier to rotation in this case.
More information is obtained by analysis of the spectra for
the 1-methyl substituted compounds 3 and 5. This substituent
introduces a second chiral element to the molecule so that there
are now four distinct isomers (two enantiomeric pairs of
diastereomers, Scheme 2). In the crystals of 3 analyzed, only the
(aS,S) and (aR,R) (the latter shown in Fig. 1) forms were
observed. This isomer has the 1-methyl group away from the
1
OH group. In the H and 13C NMR spectra of 3 and 5 there
are two, equal intensity sets of signals. Hence, both diastereo-
isomeric forms are present in equal concentrations in solution.
Two sharp singlets are observed for the OH resonances (Fig. 2
1
shows the H NMR of 3). Even at 130 ЊC in p-xylene-d10, the
two OH resonances for 3 are only broadened slightly. Hence, we
can conclude from this result that there is a significant barrier to
rotation about the indenyl–phenoxide bond, resulting in slow
interconversion of diastereoisomers on the NMR time-scale.
This barrier is estimated to be greater than 20.1(5) kcal molϪ1
at 130 ЊC (which would lead to coalescence of the OH
resonances).
It should be pointed out that tautomerism via 1,3 hydrogen
shifts within these indenyl phenols will not directly lead to
racemization. This is based upon the assumption that the
hydrogen shift occurs in a confacial fashion. The inden-3-yl ring
is sufficiently acidic to be de-protonated. Hence, treatment of a
Fig. 1 Molecular structure of HOC6H2{C9H5Me2-1,2}-2-But2-4,6, 3.
The (aR,R) form is shown.
D a l t o n T r a n s . , 2 0 0 3 , 4 5 8 0 – 4 5 8 9
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Scheme 2
Table 1 Selected bond distances (Å) and angles (Њ) for [CpTi-
(OC6H2{C9H7}-2-But2-4,6)Cl2], 7
Ti–O(1)
Ti–Cp
1.785(2)
2.023(3)
Ti–Cl(2)
Ti–Cl(1)
2.2554(8)
2.2581(8)
Cl(1)–Ti–Cl(2)
O(1)–Ti–Cl(1)
O(1)–Ti–Cl(2)
Ti–O(1)–C(11)
100.24(4)
103.74(6)
104.89(6)
158.7(1)
O(1)–Ti–Cp
Cl(1)–Ti–Cp
Cl(2)–Ti–Cp
118.1(1)
113.36(9)
114.41(8)
Table 2 Selected bond distances (Å) and angles (Њ) for [CpTi-
(OC6H2{C9H6Me-2}-2-But2-4,6)Cl2], 8
Ti–O(1)
Ti–Cp
1.784(1)
2.030(2)
Ti–Cl(2)
Ti–Cl(1)
2.2575(6)
2.2574(6)
Cl(1)–Ti–Cl(2)
O(1)–Ti–Cl(1)
O(1)–Ti–Cl(2)
Ti–O(1)–C(11)
100.87(2)
106.08(5)
102.83(4)
157.8(1)
O(1)–Ti–Cp
Cl(1)–Ti–Cp
Cl(2)–Ti–Cp
118.00(8)
113.95(7)
113.20(7)
Fig. 2 1H NMR (p-xylene-d10, 20 ЊC) spectrum of HOC6H2{C9H5Me2-
2,3}-2-But2-4,6, 3. * Protio impurity.
pentane solution of 1 with two equivalents of BunLi in hexane
led to the di-lithio salt 6 as a white powder.
Table 3 Selected bond distances (Å) and angles (Њ) for [CpTi-
(OC6H2{C9H5Me2-1,2}-2-But2-4,6)Cl2], 9
Synthesis of Cp–titanium derivatives of 2-(1-indenyl)-4,6-di-tert-
butylphenoxides
Ti–O(1)
Ti–Cp
1.788(2)
2.030(3)
Ti–Cl(1)
Ti–Cl(2)
2.2621(8)
2.2581(8)
Reaction of the phenols with [CpTiCl3]17 in the presence of
pyridine has previously been used to generate a variety of
corresponding mono-aryloxides.16d Reaction with 1–4 leads to
formation of the corresponding di-chlorides 7–10 in good yield
(Scheme 3). No evidence was obtained for the de-protonation of
the indenyl ring in these reactions. The spectroscopic and struc-
tural data on 7–10 are consistent with the presence of an inden-
3-yl ring in all cases. All four compounds were structurally
characterized (Tables 1–4) and ORTEP views of 8 and 9 are
shown in Fig. 3 and 4. In all four compounds both the (aR)
and (aS) forms are present within the unit cells (Scheme 3).
The structural parameters are comparable and similar to
Cl(1)–Ti–Cl(2)
O(1)–Ti–Cl(1)
O(1)–Ti–Cl(2)
Ti–O(1)–C(11)
99.59(3)
107.15(6)
103.44(6)
157.7(2)
O(1)–Ti–Cp
Cl(1)–Ti–Cp
Cl(2)–Ti–Cp
117.6(1)
113.1(1)
114.1(1)
those reported for previously isolated [CpTi(OAr)Cl2] com-
pounds.16,18 The Ti–O–Ar angles in 7–10 span the narrow range
of 157–160Њ. Large M–O–Ar angles are a common feature of
early d-block metal aryloxide compounds.19 In all four com-
pounds a conformation is adopted in the solid state in which the
plane of the phenoxy ring is oriented approximately co-planar
D a l t o n T r a n s . , 2 0 0 3 , 4 5 8 0 – 4 5 8 9
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Scheme 3
Table 4 Selected bond distances (Å) and angles (Њ) for [CpTi-
(OC6H2{C9H4Me3-2,4,7}-2-But2-4,6)Cl2], 10
Ti–O(1)
Ti–Cp
1.789(2)
2.020(3)
Ti–Cl(1)
Ti–Cl(2)
2.2634(8)
2.2597(8)
Cl(1)–Ti–Cl(2)
O(1)–Ti–Cl(1)
O(1)–Ti–Cl(2)
Ti–O(1)–C(11)
100.80(3)
101.97(6)
107.43(6)
159.9(2)
O(1)–Ti–Cp
Cl(1)–Ti–Cp
Cl(2)–Ti–Cp
118.7(1)
113.23(9)
112.8(1)
with the Cp ring. An identical geometry is adopted for all other
reported [CpTi(OAr)Cl2] compounds.16 In 7–10 the indenyl ring
packs pointing towards the Cp ring, making torsion angles with
the phenoxy ring of 56, 73, 71 and 75Њ for 7–10, respectively.
At ambient temperatures the potentially diastereotopic
methylene protons in the ortho-inden-3-yl groups of 7 appear as
a broad singlet in the 1H NMR spectra due to indenyl rotation
on the NMR timescale. At lower temperatures this signal
broadens and resolve into the AB pattern expected for the static
structure. Variable temperature NMR studies of 7 in toluene-d8
allow the barrier to inden-3-yl rotation (enantiomer inter-
conversion) to be estimated at 13.9(5) kcal molϪ1 (at 20 ЊC). In
contrast the 2-methyl derivative 8 (Fig. 5) and 2,4,7-trimethyl
substituted compound 10 show sharp, well-resolved AB
patterns for these methylene protons at ambient temperature.
Fig.
3
Molecular structure of [CpTi(OC6H2{C9H6Me-2}-2-But2-
4,6)Cl2], 8.
In the case of the 1,2-dimethyl substituted 9, two enantio-
meric pairs of diastereomers are possible. In the solid state only
the (aS,S) and (aR,R) forms were observed, with the 1-methyl
group pointing away from the titanium coordination sphere. In
solution only one major set of H and 13C NMR resonances
1
D a l t o n T r a n s . , 2 0 0 3 , 4 5 8 0 – 4 5 8 9
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Table 5 Selected bond distances (Å) and angles (Њ) for [CpTi-
(OC6H2{C9H7}-2-But2-4,6)(µ-Cl)]2, 11
Ti–O(1)
Ti–Cp
1.819(2)
2.028(5)
Ti–Cl
Ti–Cl(1)
2.420(1)
2.430(1)
Cl–Ti–Cl
89.96(3)
104.45(7)
118.0(1)
120.1(1)
Ti–Cl–Ti
Cl–Ti–O(1)
Cl–Ti–Cp
90.04(3)
102.44(9)
116.9(2)
154.7(2)
Cl–Ti–O(1)
Cl–Ti–Cp
O(1)–Ti–Cp
Ti–O(1)–C(11)
Fig. 4 Molecular structure of [CpTi(OC6H2{C9H5Me2-1,2}-2-But2-
4,6)Cl2], 9.
Scheme 4
Fig. 5 1H NMR (C6D6) spectrum of [CpTi(OC6H2{C9H6Me-2}-2-
But2-4,6)Cl2], 8.
were observed. Hence, it appears that replacement of the
phenolic proton by the much bulkier [CpTiCl2] unit destabilizes
the (aS,R) and (aR,S) forms in solution.
Attempted deprotonation and formation of a constrained
geometry chelate ring
The indenyl ring of the ligand used in this study has enantio-
topic faces. Hence, metallation of the indenyl ring (deproton-
ation and metal binding) can lead to two enantiomeric com-
plexes. The nomenclature used to define the planar chirality of
the chelates thus obtained is based upon that used for ansa-
metallocenes.20 The planar chirality of the indenyl ring is
assigned (pR) or (pS) based on the Cahn–Ingold–Prelog con-
figuration of the 1-position of the metal bound ring (Scheme 4).
In this case, the 1-position is the stereogenic center bound to the
ortho-position of the phenoxide nucleus. The (aR) and (aS)
forms of the parent ligand lead directly to the (pR) and (pS)
chelates, respectively. It should also be noted that the chirality
of (pR) and (pS) forms are not affected by the presence of
chelation via the phenoxide oxygen. Interconversion (racemiz-
ation) can only occur via “flipping” of the indenyl ring.
Attempted de-protonation of the inden-3-yl ring in 7 by
treatment with n-BuLi or MeLi did not lead to the formation of
chelate rings. Instead n-BuLi resulted in reduction of the
metal center and formation of a compound 11 containing two
d1-Ti() metal centers linked by chloride bridges (Scheme 4).
The solid-state structure of 11 (Table 5, Fig. 6) shows a transoid
arrangement of Cp and aryloxide ligands similar to that found
in related compounds.16 Each molecule (Fig. 6) can be seen to
contain both (aR) and (aS) forms of the ligand (crystallo-
graphic inversion center). This reduction process presumably
Fig.
6
Molecular structure of [CpTi(OC6H2{C9H7}-2-But2-4,6)-
(µ-Cl)]2, 11.
involves alkylation at the Ti–Cl bond followed by a β-hydrogen
abstraction/elimination pathway leading to an unstable hydride
intermediate. The reaction with methyl lithium also leads to
alkylation of the Ti–Cl bonds and formation of the dimethyl
compound 12 (Scheme 4). Both Ti–Me groups in 12 appear as
one broad singlet in both the 1H and 13C NMR spectra at ambi-
ent temperatures but appear as two well-resolved resonances at
lower temperatures (Fig. 7). From the coalescence temperature
the barrier to indenyl rotation can be estimated to be 13.4(5)
kcal molϪ1 at Ϫ5 ЊC, slightly lower than that measured for the
dichloride 7. These barriers are much lower than that measured
for corresponding 2-(1-naphthyl)phenoxides. In the case of the
direct 2-(1-naphthyl-4,6-di-tert-butlyphenoxide analogue of 12,
1
two sharp, distinct Ti–Me resonances are observed in the H
NMR spectrum even at 90 ЊC.16b
Reaction of [CpTiCl3] with the di-lithio (doubly deproton-
ated ligand) compound 6 did lead to the formation of a
D a l t o n T r a n s . , 2 0 0 3 , 4 5 8 0 – 4 5 8 9
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Table 6 Selected bond distances (Å) and angles (Њ) for [CpTi-
(OC6H2{η5-C9H6}-2-But2-4,6)Cl], 13
Ti(1)–O(1)
1.915(3)
2.365(5)
2.334(5)
2.370(5)
2.398(5)
2.386(5)
2.375(1)
2.332(4)
2.363(4)
2.399(5)
2.514(5)
2.414(4)
Ti(2)–O(2)
1.908(3)
2.366(4)
2.348(4)
2.378(4)
2.420(4)
2.397(4)
2.385(1)
2.366(4)
2.363(4)
2.374(4)
2.491(4)
2.433(4)
Ti(1)–C(111)
Ti(1)–C(112)
Ti(1)–C(113)
Ti(1)–C(114)
Ti(1)–C(115)
Ti(1)–Cl(1)
Ti(1)–C(121)
Ti(1)–C(122)
Ti(1)–C(123)
Ti(1)–C(124)
Ti(1)–C(129)
Ti(2)–C(221)
Ti(2)–C(212)
Ti(2)–C(213)
Ti(2)–C(214)
Ti(2)–C(215)
Ti(2)–Cl(2)
Ti(2)–C(221)
Ti(2)–C(222)
Ti(2)–C(223)
Ti(2)–C(224)
Ti(2)–C(229)
O(1)–Ti(1)–Cl(1)
Ti(1)–O(1)–C(11)
92.20(9)
124.8(3)
O(2)–Ti(2)–Cl(2)
Ti(2)–O(2)–C(21)
95.38(9)
127.3(3)
Fig. 8 Molecular structure of [CpTi(OC6H2{η5-C9H6}-2-But2-4,6)Cl],
13.
Fig. 7 1H NMR (toluene-d8) spectrum of [CpTi(OC6H2{C9H7}-2-
But2-4,6)Me2], 12, at 20 and Ϫ45 ЊC.
Fig. 9 1H NMR (C6D6) spectrum of [CpTi(OC6H2{η5-C9H6}-2-But2-
4,6)Cl], 13.
1
towards the Cp group, Fig. 8). In solution only one set of H
(Fig. 9) and 13C NMR signals were observed indicating the
presence of this single diastereoisomer.
Besides its inherent stereochemistry, compound 13 also is of
interest as it contains both a “regular” cyclopentadienyl group
and the new, chelated indenyl group bound to the same metal
center. The structural parameters for the bonding of these two
groups are highlighted in a “radar plot” of Ti–C distances in
Fig. 10. The crystal contains two independent molecules within
the unit cell. The Cp ligand is symmetrically bound to the
titanium metal with equal Ti–C distances. The Ti–C(indenyl)
distances are more irregular. The Ti–C(1) (ipso carbon bound
to the phenoxy ring) distance is the shortest contact with the
longest being to the aromatic carbon atoms, C(4) and C(5). The
“slip value” has been defined as [∆ = avg. d{M–C(3a),(7a)} Ϫ
avg. d{M–C(1),(3)}].21 This corresponds to [∆ = avg. d{M–C-
(124),(129)} Ϫ avg. d{M–C(121),(123)] in the labeling used
Scheme 5
chelated indenyl-phenoxide derivative 13 (Scheme 5). The com-
pound was structurally characterized and an ORTEP view
is shown in Fig. 8 with selected bond distances and angles in
Table 6. The chelation also introduces a further stereochemical
element in that the pseudo-tetrahedral titanium now becomes a
chiral center. Hence, there are two diastereoisomers possible for
13 with the plane of the indenyl ring pointing either towards or
away from the Cp substituent (Scheme 5). In the solid state only
the (pS,R) and (pR,S) forms were observed (indenyl oriented
D a l t o n T r a n s . , 2 0 0 3 , 4 5 8 0 – 4 5 8 9
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1
8.72%. (HRMS): calcd: 320.2140, found: 320.2139. H NMR
3
(CDCl3, 30 ЊC): δ 7.27–7.67 (aromatics); 6.78 [t, J(1H–1H) =
3
2.1 Hz, CH ]; 5.68 (s, OH ); 3.69 [d, J(1H–1H) = 1.6 Hz, CH2];
1.57 (s), 1.44 (s, CMe3). 13C NMR (CDCl3, 30 ЊC): δ 149.3
(O–C); 144.4, 144.2, 141.7, 141.5, 135.3, 132.7, 126.5, 125.5,
124.1, 123.9, 123.8, 121.2, 120.9 (unsaturated C); 38.7 (CH2);
35.1, 34.3 (CMe3); 31.7, 29.7 (CMe3).
Synthesis of 2-(1-methylinden-3-yl)-4,6-di-tert-butylphenol (2)
A solution of 2-bromo-4,6-di-tert-butylphenol (105 g, 0.368
mol) in 500 mL of diethyl ether was cooled to 0 ЊC under an
atmosphere of nitrogen. To the stirred solution was slowly
added BunLi (305 mL of a 2.5M hexane solution, 0.77 mol).
The solution was slowly warmed to room temperature with
magnetic stirring for 5 h. The white solution was then cooled to
0 ЊC in an ice bath, and freshly distilled 2-methylindanone (49 g,
0.34 mol) in diethyl ether was added dropwise over 30 min via
an addition funnel. The yellow solution was allowed to warm to
room temperature followed by stirring overnight. The reaction
mixture was quenched with 100 mL of a saturated ammonium
chloride solution and poured into a 2000 mL Erlenmeyer flask
containing 500 g of ice and 100 mL of concentrated HCl. The
mixture was stirred for 30 min and the aqueous layer extracted
three times with 100 mL portions of diethyl ether. The ether
extracts were combined and washed three times with water (200
mL), dried with MgSO4, and evaporated to dryness to produce
a brown oil. The crude material was vacuum distilled (0.5
mmHg) at 150 ЊC to remove indanone and 2,4-di-tert-butyl-
phenol to afford a reddish brown crystalline residue. Dis-
solution of this material in 300 mL of pentane followed by
cooling to Ϫ20 ЊC produced a white crystalline material over-
night (27 g, 24%). Anal. Calcd for C24H30O: C, 86.18; H, 9.04.
Found: C, 86.21; H, 8.88%. (HRMS): calcd: 334.2297, found:
334.2302. 1H NMR (CDCl3, 25 ЊC): δ 7.09–7.51 (m, aromatics);
5.16 (s, OH ); 3.56 (s, CH2); 2.12 [s, CH3]; 1.48 (s), 1.35 (s,
CMe3). 13C NMR (CDCl3, 25 ЊC): δ 149.2 (O–C); 145.8, 143.9,
142.7, 141.6, 135.0, 134.7, 126.5, 124.5, 124.3, 123.5, 123.4,
123.3, 119.9, 112.3 (unsaturated C); 43.1 (CH2); 35.1, 34.3
(CMe3); 31.7, 29.6 (CMe3); 15.2 (CH3).
Fig. 10 “Radar” plot of the Ti–C(indenyl) (solid line) and Ti–Cp
(dashed line) distances in compound 13 (two independent molecules
within the unit cell). The coordination is exaggerated by using a plot
scale of 2.2–2.5 Å from the metal center.
here. For compound 13 the value of ∆ = 0.092 and 0.028 Å for
the two independent molecules. For a “true η5-indenyl” this
value would be close to 0 Å whereas values of ∼0.75 Å are
calculated for “true η3-indenyl” compounds.21 Hence, based
upon this parameter, there is only minor slippage away from η5-
bonding. The electronic configuration of the Ti metal center in
13 is formally 16-electron. The Ti–O–C angle for the chelated
indenyl-phenoxide in 13 is 125 and 127Њ (Table 6). The Ti–O
distances of 1.915(3) and 1.908(3) Å are significantly longer
than the 1.78 Å found in electronically less saturated 7–10
(Tables 1–4), indicating that there is decreased oxygen-p to
metal-d, π-donation.
Experimental
General details
Synthesis of 2-(1,2-dimethylinden-3-yl)-4,6-di-tert-butylphenol
(3)
All operations were carried out under a dry nitrogen atmos-
phere using standard Schlenk techniques. The hydrocarbon
solvents were distilled from sodium/benzophenone and stored
Using an identical procedure as for 1, 65 g of 2-bromo-4,6-di-
tert-butylphenol (0.22 mol) was treated with BunLi (180 mL of
a 2.5 M hexane solution, 0.45 mol), followed by addition of 35
g of 2,3-dimethylindanone (0.21 mol). Hydrolysis and work-up
of the reaction mixture produced a brown oil that was vacuum
distilled at 150 ЊC to remove indanone and 2,4-di-tert-butyl-
phenol. The reddish brown residue was dissolved in 400 mL of
pentane and cooled to Ϫ20 ЊC to produce a light yellow crystal-
line material overnight (22 g, 30%). Anal. Calcd for C25H32O: C,
86.15; H, 9.25. Found: C, 85.99; H, 9.26%. (HRMS): calcd:
348.2453, found: 348.2454. 1H NMR (C6D6, 25 ЊC): δ 7.10–7.61
(m, aromatics); 5.23 (s), 5.11 (s, OH ); 3.01 (m, CH ); 1.72 (s),
1.71 (s, CH3); 1.66 (s), 1.65 (s), 1.33 (s), 1.32 (s, CMe3); 1.09 (d),
over sodium ribbons under nitrogen until use. The H and 13C
1
NMR spectra were recorded on a Varian Associates Gemini-
200, Inova-300, or General Electric QE-300 spectrometer and
referenced to protio impurities of commercial benzene-d6 as
internal standard. Elemental analyses and molecular structures
were obtained through Purdue in-house facilities.
Synthesis of 2-(inden-3-yl)-4,6-di-tert-butylphenol (1)
A sample of 2-bromo-4,6-di-tert-butyl phenol (143 g, 0.50 mol)
was dissolved in diethyl ether (500 mL) and cooled to 0 ЊC using
an ice/acetone bath. Under a nitrogen atmosphere BunLi was
added (400 mL of a 2.5M hexane solution, 1.0 mol). The solu-
tion became white in color and was allowed to slowly warm to
room temperature over the course of 2 h. To this solution was
slowly added 1-indanone (66.3 g, 0.50 mol) dissolved in ether
and the yellow solution was allowed to stir overnight. The solu-
tion was then hydrolyzed with 6 M HCl (300 mL) and allowed
to stir for 1 h. The orange ether layer was separated from the
aqueous layer, washed three times with water (500 mL), dried
with MgSO4, and evaporated to dryness affording a brown oil.
This oil was vacuum distilled to 150 ЊC to remove 1-indanone
and 2,4-di-tert-butylphenol leaving a brown oil (100 g, 62%).
Elution of this oil on silica-gel with hexane afforded a yellow oil
that gave white crystalline material from cold pentane. Anal.
Calcd for C23H28O: C, 86.20; H, 8.81. Found: C, 86.23; H,
3
0.99 [d, J(1H–1H) = 7.5 Hz, CH3]. 13C NMR (CDCl3, 25 ЊC):
δ 149.2, 149.0 (O–C); 148.9, 148.5, 144.4, 141.6, 134.9, 133.3,
126.6; 124.8, 124.7, 124.5, 124.3, 123.4, 122.6,, 120.5, 120.4,
119.8; (unsaturated C); 47.7, 47.4 (CH); 35.0, 34.3 (CMe3);
31.7, 29.6 (CMe3); 16.2, 15.9, 13.3, 13.2 (CH3).
Synthesis of 2-(2,4,7-trimethylinden-3-yl)-4,6-di-tert-
butylphenol (4)
Using an identical procedure as for 1, 68 g of 2-bromo-4,6-di-
tert-butylphenol (0.22 mol) was treated with BunLi (180 mL of
a 2.5 M hexane solution, 0.45 mol), followed by addition of
35 g of 2,4,7-trimethylindanone (0.20 mol). Hydrolysis and
work-up of the reaction mixture produced a brown oil that was
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vacuum distilled at 150 ЊC to remove indanone and 2,4-di-tert-
butylphenol. The reddish brown residue was dissolved in 300
mL of pentane and cooled to Ϫ20 ЊC to produce a white crys-
talline material overnight (25 g, 34%). Anal. Calcd for C26H34O:
C, 86.13; H, 9.45. Found: C, 85.90; H, 9.19%. (HRMS): calcd:
362.2610, found: 362.2609. 1H NMR (C6D6, 25 ЊC): δ 7.56 (d),
7.16 (s), 6.93 (s, aromatics); 5.09 (s, OH ); 2.80 (d), 2,84 [d,
2J(1H–1H) = 13 Hz, CH2); 2.20 (s), 2.06 (s), 1.75 (s, CH3); 1.65
(s), 1.33 (s, CMe3). 13C NMR (C6D6, 25 ЊC): δ 150.7, 150.12,
144.8, 142.1, 141.9, 141.4, 135.6, 135.2, 135.0, 130.1, 130.0,
128.8, 128.3, 127.8, 127.3, 126.1, 125.2, 124.4, 123.4 (unsatur-
ated C); 41.7 (CH2); 35.3, 34.4 (CMe3); 31.8, 29.9 (CMe3); 18.7,
18.4, 14.5 (CH3).
was stirring 2 (2.44 g, 7.29 mmol) dissolved in toluene was
slowly added. The solution slowly turned deep red and stirring
was continued overnight. Filtration of the pyridinium chloride,
followed by removal of the solvent under vacuum afforded an
orange–red powder. Dissolution of the crude material in hot
hexane produced deep red crystals of 8 on cooling (2.20 g,
58.4%). Anal. Calcd for C29H34Cl2OTi: C, 67.32; H, 6.62.
Found: C, 67.21; H, 6.58%. 1H NMR (C6D6, 25 ЊC): δ 7.55 (d),
7.33–7.45 (m), 7.25 (t), 7.11–7.16 (m, aromatics); 5.79 (s, C5H5);
2
3.59, 3.05 (AB, J(1H–1H) = 12.8 Hz, CH2); 2.05 (s, CH3); 1.59
(s), 1.26 (s, CMe3). 13C NMR (C6D6, 25 ЊC): δ 165.5 (Ti–O–C);
148.0, 146.8, 146.2, 143.5, 138.5, 135.2, 126.8, 125.7, 124.4,
123.0, 121.2, 118.6 (unsaturated C); 42.8 (CH2); 35.8, 34.7
(CMe3); 31.5, 30.7 (CMe3); 15.9 (CH3).
Synthesis of 2-(1,2,4,7-tetramethylinden-3-yl)-4,6-di-tert-
butylphenol (5)
Synthesis of [CpTi(OC6H2{C9H5Me2-1,2}-2-But2-4,6)Cl2] (9)
Using an identical procedure as for 1, 38 g of 2-bromo-4,6-di-
tert-butylphenol (0.13 mol) was treated with BunLi (110 mL of
a 2.5 M hexane solution, 0.28 mol), followed by addition of
23 g of 2,4,7-trimethylindanone (0.20 mol). Hydrolysis and
work-up of the reaction mixture produced a brown oil that was
vacuum distilled at 150 ЊC. The reddish brown residue was
eluted over silica gel with hexane to afford an orange powder
(9.5 g, 21%). Anal. Calcd for C26H34O: C, 86.11; H, 9.64.
Found: C, 85.08; H, 9.74%. (HRMS): calcd: 376.2766, found:
376.2758. 1H NMR (C6D6, 25 ЊC): δ 7.55 (s), 6.70 (s, aromatics);
5.20 (s), 5.06 (s, OH ); 3.10–2.91 (m, CH ); 2.27 (s), 2.25 (s), 2.04
(s), 1.68 (s, CH3); 1.66 (s), 1.31 (s, CMe3); 1.13 (d), 0.99 [d,
3J(1H–1H) = 7.5 Hz, CH3]. 13C NMR (C6D6, 25 ЊC): δ 150.8,
150.2 (O–C); 150.1, 150.0, 147.3, 147.2, 142.2, 141.6, 135.0,
134.4, 133.5, 130.8, 130.3, 127.8, 127.3, 126.1, 125.2, 124.4,
123.4 121.7 (unsaturated C); 47.0, 46.8 (CH2); 35.3, 34.4
(CMe3); 31.8, 29.9 (CMe3); 18.8, 18.6, 15.2, 14.0, 12.7, 12.6
(CH3).
A flask was charged with [CpTiCl3] (1.12 g, 5.11 mmol), pyrid-
ine (1.5 mL, 19 mmol), and toluene (∼50 mL). As this mixture
was stirring 3 (1.78 g, 5.11 mmol) dissolved in toluene was
slowly added. The solution slowly turned deep red and stirring
was continued overnight. Filtration of the pyridinium chloride,
followed by removal of the solvent under vacuum afforded an
orange–red powder. Dissolution of the crude material in hot
hexane produced deep red crystals of a single diastereomer of
9 on cooling (1.00 g, 36.9%). X-ray diffraction analysis of the
isolated crystals established the configuration as the epimeric
(aS,S)/(aR,R) isomers. Anal. Calcd for C30H36Cl2OTi: C, 67.81;
1
H, 6.83. Found: C, 67.61; H, 6.86%. H NMR (C6D6, 25 ЊC):
δ 7.55 (d), 7.32–7.45 (m), 7.24 (t), 7.15 (t, aromatics); 5.80 (s,
3
C5H5); 3.64 (q, J(1H–1H) = 7.5 Hz, CH–Me); 2.04 (s, 2-CH3);
1.59 (s), 1.25 (s, CMe3); 1.15 (d, 3J(1H–1H) = 7.5 Hz, CH–Me).
13C NMR (C6D6, 25 ЊC): δ 165.6 (Ti–O–C); 151.9, 149.2, 146.6,
146.3, 138.6, 133.9, 127.1, 125.9, 124.7, 123.6, 123.1, 121.2,
121.1, 118.6 (unsaturated C); 47.3 (CH2); 35.8, 34.7 (CMe3);
31.5, 30.7 (CMe3); 15.4, 13.9 (CH3).
Synthesis of [Li2(OC6H2-Ind-2-But-4,6)] (6)
Synthesis of [CpTi(OC6H2{C9H4Me3-2,4,7}-2-But2-4,6)Cl2] (10)
To a stirred pentane (200 mL) solution of 1 (10 g, 34 mmol) was
slowly added BunLi (30 mL of a 2.5M hexane solution, 75
mmol). A yellow precipitate was formed upon complete addi-
tion of BunLi, and stirring was continued for an additional
45 min. The yellow solid was rinsed five times with pentane then
dried under vacuum affording a yellow powder that was used
without further purification (9.0 g, 87%).
A flask was charged with [CpTiCl3] (1.22 g, 5.56 mmol), pyrid-
ine (1.5 mL, 19 mmol), and toluene (∼50 mL). As this mixture
was stirring 4 (2.02 g, 5.56 mmol) dissolved in toluene was
slowly added. The solution slowly turned deep red and stirring
was continued overnight. Filtration of the pyridinium chloride,
followed by removal of the solvent under vacuum afforded an
orange–red powder. Dissolution of the crude material in hot
hexane produced deep red crystals of 10 on cooling (2.11 g,
69.6%). Anal. Calcd for C31H38Cl2OTi: C, 68.27; H, 7.02.
Found: C, 68.00; H, 6.90%. 1H NMR (C6D6, 25 ЊC): δ 7.48 (d),
7.24 (d), 6.97 (q, aromatics); 5.93 (s, C5H5); 3.44, 2.90 (AB,
2J(1H–1H) = 13.0 Hz, CH2); 2.25, 2.23, 2.01 (s, CH3); 1.56 (s),
1.24 (s, CMe3). 13C NMR (C6D6, 25 ЊC): δ 165.3 (Ti–O–C);
146.2, 145.7, 144.5, 142.4, 138.7, 136.3, 131.3, 130.8, 130.3,
127.3, 126.9, 125.8, 123.1, 122.7, 122.1, 121.0, 119.6 (unsatur-
ated C); 41.7 (CH2); 35.8, 34.7 (CMe3); 31.5, 30.7 (CMe3); 20.2,
18.5, 15.9 (CH3).
Synthesis of [CpTi(OC6H2{C9H7}-2-But2-4,6)Cl2] (7)
A sample of [CpTiCl3] (3.0 g, 13.7 mmol) was dissolved in
benzene along with pyridine (1.7 mL, 21.0 mmol). To this solu-
tion was added 2-(inden-3-yl)-4,6-di-tert-butylphenol (4.4 g,
13.7 mmol) causing the solution to immediately to turn red and
a precipitate to form. The mixture was stirred overnight and
filtered to remove pyridinium chloride. The filtrate was evacu-
ated to dryness giving a red glassy solid that was dissolved in a
minimal amount of benzene/pentane. After sitting undisturbed
overnight red crystals (1/2 benzene per Ti) formed which were
washed with pentane and dried in vacuo (6.5 g, 94%). Anal.
Calcd for C28H32Cl2OTi: C, 66.81; H, 6.41. Calcd for C31H35-
Cl2Oti (1/2 benzene per Ti): C, 68.65; H, 6.50. Found: C, 67.79;
H, 6.42%. 1H NMR (C6D6, 30 ЊC): δ 7.13–7.61 (aromatics); 6.61
(t, CH ); 5.81 (s, C5H5); 3.36 (br, CH2); 1.61 (s), 1.28 [s,
Synthesis of [CpTi(OC6H2{C9H7}-2-But2-4,6)Me2] (12)
A sample of [CpTi(OC6H2{C9H7}-2-But2-4,6)Cl2] (470 mg,
0.93 mmol) was dissolved in benzene and MeLi (51 mg,
2.3 mmol) slowly added with stirring. The solution was stirred
for 6 h, filtered, and the filtrate evacuated to dryness affording a
1
C(CH3)3]. H NMR (C7D8, Ϫ30 ЊC): δ 6.72–7.58 (aromatics);
2
6.60 (br, CH ); 5.67 (s, C5H5); 3.48 (d), 3.12 [d, J(1H–1H) =
1
yellow oil that was very soluble in hydrocarbon solvents. H
13.8 Hz, CH2); 1.58 (s), 1.25 (s, CMe3). Selected 13C NMR
(C6D6, 30 ЊC): δ 165.5 (Ti–O–C); 121.0 (C5H5); 38.7 (CH2);
35.9, 34.7 (CMe3); 31.5, 30.6 (CMe3).
4
NMR (C6D6, 30 ЊC): δ 7.57 (d), 7.33 [d, J(1H–1H) = 2.4 Hz,
meta C6H2]; 7.04–7.55 (other aromatics); 6.29 (t, CH ); 5.59 (s,
C5H5); 3.05 (d, CH2); 1.60 (s), 1.28 (s, CMe3); 0.64 (br, Ti–Me).
Selected 13C NMR (C6D6, 30 ЊC): δ 161.7 (Ti–O–C); 114.3
(C5H5); 57.7 (br, Ti–Me); 38.4 (CH2); 35.7, 34.5 (CMe3); 31.7,
30.5 (CMe3). 1H NMR (C7D8, Ϫ45 ЊC): δ 6.97–7.61 (aromatics);
Synthesis of [CpTi(OC6H2{C9H6Me-2}-2-But2-4,6)Cl2] (8)
A flask was charged with [CpTiCl3] (1.60 g, 7.29 mmol), pyrid-
ine (2.0 mL, 25 mmol), and toluene (∼50 mL). As this mixture
2
6.31 (d, CH ); 5.50 (s, C5H5); 2.90 (d), 3.10 [d, J(1H–1H) = 13
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Hz, CH2]; 1.64 (s), 1.30 (s, CMe3); 0.76 (s), 0.65 (s, Ti–Me).
Selected 13C NMR (C7D8, Ϫ45 ЊC): δ 161.6 (Ti–O–C); 114.3
(C5H5); 58.8, 56.8 (Ti–Me); 38.3 (CH2); 35.8, 34.6 (CMe3); 31.7,
30.3 (CMe3).
Synthesis of [CpTi(OC6H2-{ꢀ5-Ind}-2-But-4,6)Cl] (13)
A flask was charged with [CpTiCl3] (1.55 g, 7.07 mmol) and
benzene (100 mL). As this mixture was stirring, solid
[Li2(OC6H2–{C9H6}-2-But2-4,6)] (2.35 g, 7.07 mmol) was slowly
added. The solution immediately turned deep red and stirring
was continued overnight. Filtration of the crimson product
mixture over Celite®, followed by removal of the solvent under
vacuum, afforded glassy red solid. Dissolution of the crude
material in minimal pentane produced crimson blocks of a
single diastereomer of 13 on standing for days (1.05 g, 31.8%).
X-ray diffraction analysis of the crystals established the con-
figuration as the (p-R,S)/(p-S,R) isomers. Anal. Calcd for
C28H31ClOTi: C, 72.03; H, 6.69. Found: C, 72.07; H, 6.81%. 1H
NMR (C6D6, 25 ЊC): δ 7.55 (d), 7.25 (d), 6.99 (t), 6.84 (t), 6.57
3
(t, aromatics); 7.37 (d), 5.64 [d, J(1H–1H) = 3.3 Hz, η5-CH ];
5.50 (s, C5H5); 1.50 (s), 1.35 (s, CMe3). 13C NMR (C6D6, 25 ЊC):
δ 176.7 (Ti–O–C); 144.1, 139.0, 138.6, 134.8, 128.4, 127.4,
127.1, 126.1, 125.8, 125.2, 124.8, 124.0, 123.4, 122.5 (unsatur-
ated C); 119.3 (C5H5); 98.8 (η5-CH); 35.2, 34.6 (CMe3); 31.9,
30.0 (CMe3).
X-ray data collection and reduction
Crystal data and data collection parameters are contained in
Table 7. A suitable crystal was mounted on a glass fiber in a
random orientation under a cold stream of dry nitrogen. Pre-
liminary examination and final data collection were performed
with MoKα radiation (λ = 0.71073 Å) on a Nonius Kappa
CCD. Lorentz and polarization corrections were applied to the
data.22 An empirical absorption correction using SCALEPACK
was applied.23 Intensities of equivalent reflections were
averaged. The structure was solved using the structure solu-
tion program PATTY in DIRDIF92.24 The remaining atoms
were located in successive difference Fourier syntheses. Hydro-
gen atoms were included in the refinement but restrained to
ride on the atom to which they are bonded. The structures
were refined by full-matrix least-squares using observed data
where the function minimized was Σw(|Fo|2 Ϫ|Fc|2)2 and the
2
weight w is defined as w = 1/[σ2(Fo )ϩ(0.0585P)2 ϩ1.4064P]
where P = (Fo2 ϩ2Fc2)/3. Scattering factors were taken from the
International Tables for Crystallography.25 Refinement was per-
formed on a AlphaServer 2100 using SHELX-97.26 Crystallo-
graphic drawings were done using ORTEP.27
CCDC reference numbers 218466–218475.
See http://www.rsc.org/suppdata/dt/b3/b310415j/ for crystal-
lographic data in CIF or other electronic format.
Acknowledgements
We thank the National Science Foundation (Grant CHE-
0078405) for financial support of this research.
References
1 P. J. Shapiro, E. E. Bunel, W. P. Shaefer and J. E. Bercaw,
Organometallics, 1990, 9, 867.
2 (a) R. F. Jordan, Adv. Organomet. Chem., 1991, 32, 325; (b) H. H.
Brintzinger, D. Fischer, R. Mülhaupt, B. Rieger and R. M.
Waymouth, Angew. Chem., Int. Ed. Engl., 1995, 34, 1143;
(c) M. Bochmann, J. Chem. Soc., Dalton Trans., 1996, 255;
(d ) W. Kaminsky and M. Arndt, Adv. Polym. Sci., 1997, 127, 143;
(e) L. Resconi, L. Cavallo, A. Fait and F. Piemontesi, Chem. Rev.,
2000, 100, 1253; ( f ) E. Y. Chen and T. J. Marks, Chem. Rev., 2000,
100, 1391; (g) K. A. Abboud, P. N. Nickias and E. Y.-X. Chen,
Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 2002, 58, m41.
D a l t o n T r a n s . , 2 0 0 3 , 4 5 8 0 – 4 5 8 9
4588

View Article Online
3 M. E. Rerek, L-N. Ji and F. Basolo, J. Chem. Soc., Chem. Commun.,
1983, 1208.
4 M. J. Calhorda and L. F. Veiros, Coord. Chem. Rev., 1999, 185–186,
37.
5 S. L. Shaw, J. J. Storhoff, S. Cullison, C. E. Davis, G. Holloway,
R. J. Morris, J. C. Huffman and J. C. Bollinger, Inorg. Chim. Acta,
1999, 292, 220 and references therein.
6 (a) M. J. Burk, S. L. Colletti and R. L. Halterman, Organometallics,
1991, 10, 2998; (b) W. W. Ellis, K. Hollis, W. Odenkirk, J. Whelan,
R. Ostrander, A. L. Rheingold and B. Bosnich, Organometallics,
1993, 12, 4391; (c) S. Martin and H. Brintzinger, Inorg. Chim. Acta,
1998, 280, 189 and other papers within the series.
(r) S. L. Hart, D. J. Duncalf, J. J. Hastings, A. McCamley and
P. C. Taylor, J. Chem. Soc., Dalton Trans., 1996, 2843; (s) J. C. W.
Chien, G. H. Llinas, M. D. Rausch, G.-Y. Lin and H. H. Winter,
J. Am. Chem. Soc., 1991, 113, 8569; (t) J. Klosin, W. J. Kruper Junior,
P. N. Nickias, G. R. Roof, P. De Waele and K. A. Abboud,
Organometallics, 2001, 20, 2663; (u) S. R. Hitchcock, J. J. Situ,
J. A. Covel, M. M. Olmstead and M. H. Nantz, Organometallics,
1995, 14, 3732.
12 Some aspects of this work have been communicated, see: (a) M. G.
Thorn, P. E. Fanwick, R. W. Chesnut and I. P. Rothwell, Chem.
Commun., 1999, 2543; (b) L. E. Turner, M. G. Thorn, P. E. Fanwick
and I. P. Rothwell, Chem. Commun., 2003, 1034.
7 (a) G. W. Coates and R. M. Waymouth, Science, 1995, 267, 217;
(b) S. Lin and R. M. Waymouth, Macromolecules, 1999, 32, 8283;
(c) P. Witte, T. K. Lal and R. M. Waymouth, Organometallics, 1999,
18, 4147; (d ) J. L. Petoff, A. Maciejewski, Tony, T. K. Lal and
R. M. Waymouth, J. Am. Chem. Soc., 1998, 120, 11316.
13 For some other constrained geometry indenyl titanium compounds,
see: (a) K. A. Abboud, P. N. Nickias and E. Y.-X. Chen,
Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 2001, 57, 1408;
(b) J. Klosin, Kruper, W. J. Junior, P. N. Nickias, G. R. Roof, P. De
Waele and K. A. Abboud, Organometallics, 2001, 20, 2663.
14 E. L. Eliel, S. H. Wilen, Stereochemistry of Organic Compounds,
Wiley, New York, 1994, pp. 1142–1155.
8 For
a cyclopentadienyl-phenoxide, see: Y-X. Chen, P-F. Fu,
C. L. Stern and T. J. Marks, Organometallics, 1997, 16, 5958.
9 For the use of 2-(7-indenyl)phenoxide, see: K. Kawai and
T. Kitahara, (Fujita, Mitsui Petrochemical Ind, Japan), Jpn.
JP08,325,283, 1996 [Chem. Abstr., 1996, 126, 172048h].
10 For the stereochemical possibilities of a bis(alkoxy-Cp) system, see:
J. Christoffers and R. G. Bergman, Angew. Chem., Int. Ed. Engl.,
1995, 34, 2266.
15 P. S. Cahn, C. Ingold and V. Prelog, Angew. Chem., Int. Ed. Engl.,
1966, 5, 385.
16 (a) J. S. Vilardo, M. G. Thorn, P. E. Fanwick and I. P. Rothwell,
Chem. Commun., 1998, 2425; (b) M. G. Thorn, J. S. Vilardo, P. E.
Fanwick and I. P. Rothwell, Chem. Commun., 1998, 2427; (c) P. N.
Riley, M. G. Thorn, J. S. Vilardo, M. A. Lockwood, P. E. Fanwick
and I. P. Rothwell, Organometallics, 1999, 18, 3016; (d ) M. G.
Thorn, J. S. Vilardo, J. Lee, B. Hanna, P. E. Fanwick and I. P.
Rothwell, Organometallics, 2000, 19, 5636.
11 For publications dealing with titanium indenyl chemistry, see:
(a) R. Gyepes, I. Cisarova, M. Horacek, J. Cejka, L. Petrusova
and K. Mach, Collect. Czech. Chem. Commun., 2000, 65, 1248;
(b) M. Bochmann, L. M. Wilson, M. B. Hursthouse and
M. Motevalli, Organometallics, 1988, 7, 1148; (c) M. D. Rausch,
K. J. Moriarty, J. L. Atwood, W. E. Hunter and E. Samuel,
J. Organomet. Chem., 1987, 327, 39; (d ) J. L. Atwood, W. E. Hunter,
D. C. Hrncir, E. Samuel, H. Alt and M. D. Rausch, Inorg. Chem.,
1975, 14, 1757; (e) G. Greidanus, R. McDonald and J. M. Stryker,
Organometallics, 2001, 20, 2492; ( f ) S. L. Shaw, J. J. Storhoff,
S. Cullison, C. E. Davis, G. Holloway, R. J. Morris, J. C. Huffman
and J. C. Bollinger, Inorg. Chim. Acta, 1999, 292, 220; (g) C. A. G.
Carter, R. McDonald and J. M. Stryker, Organometallics, 1999, 18,
820; (h) J. E. Kickham, F. Guerin, J. C. Stewart, E. Urbanska and
D. W. Stephan, Organometallics, 2001, 20, 1175; (i) F. Guerin,
C. L. Beddie, D. W. Stephan, R. E. v. H. Spence and R. Wurz,
Organometallics, 2001, 20, 3466; (j) F. Gauvin, J. Britten, E. Samuel
and J. F. Harrod, J. Am. Chem. Soc., 1992, 114, 1489; (k) S. L. Hart,
D. J. Duncalf, J. J. Hastings, A. McCamley and P. C. Taylor, J. Chem.
Soc., Dalton Trans., 1996, 2843; (l ) D. O’Hare, V. Murphy, G. M.
Diamond, P. Arnold and P. Mountford, Organometallics, 1994, 13,
4689; (m) J. Okuda, P. Konig, I. L. Rushkin, Hak-Chul, Kang and
W. Massa, J. Organomet. Chem., 1995, 501, 37; (n) R. L. Halterman,
D. Combs and M. A. Khan, Organometallics, 1998, 17, 3900;
(o) S. Parkin, S. R. Hitchcock, H. Hope and M. H. Nantz,
Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1994, 50, 169;
(p) A. Y. Agarkov, V. V. Izmer, A. N. Riabov, L. G. Kuz’mina,
J. A. K. Howard, I. P. Beletskaya and A. Z. Voskoboynikov,
J. Organomet. Chem., 2001, 619, 280; (q) F. Gauvin, J. Britten,
E. Samuel and J. F. Harrod, J. Am. Chem. Soc., 1992, 114, 1489;
17 R. D. Gorsich, J. Am. Chem. Soc., 1958, 80, 4744.
18 (a) K. Nomura, N. Naga, M. Miki, K. Yanagi and A. Imai,
Organometallics, 1998, 17, 2152; (b) P. Gomez-Sal, A. Martin,
M. Mena, P. Royo and R. Serrano, J. Organomet. Chem., 1991, 419,
77.
19 D. C. Bradley, R. C. Mehrota, I. P. Rothwell, A. Singh, Alkoxo and
Aryloxo Derivatives of Metals; Academic Press, San Diego,
CA, 2001.
20 R. L. Halterman, in Metallocenes, ed. A. Togni and R. L.
Halterman, Wiley-VHC, Weinheim, 1998, pp. 461–462.
21 S. A. Westcott, A. K. Kakkar, G. Stringer, N. J. Taylor and
T. B. Marder, J. Organomet. Chem., 1990, 394, 777.
22 P. C. McArdle, J. Appl. Crystallogr., 1996, 239, 306.
23 Z. Otwinowski and W. Minor, Methods Enzymol., 1996, 276.
24 P. T. Beurskens, G. Admirall, G. Beurskens, W. P. Bosman, R. S.
Garcia-Granda, O. Gould, J. M. M. Smits and C. Smykalla,
The DIRDIF92 Program System, Technical Report, Crystallography
Laboratory, University of Nijmegen, The Netherlands, 1992.
25 International Tables for Crystallography, Kluwer Academic
Publishers, Dordrecht, The Netherlands, 1992, vol. C, Tables 4.2.6.8
and 6.1.1.4.
26 G. M. Sheldrick, SHELXS-97, Program for solution of crystal
structures, University of Göttingen, Germany, 1997.
27 C. K. Johnson, ORTEP-II: A FORTRAN Thermal Ellipsoid Plot
Program for Crystal Structure Illustrations, Report ORNL-
5138, Oak Ridge National Laboratory, Oak Ridge, TN, USA,
1976.
D a l t o n T r a n s . , 2 0 0 3 , 4 5 8 0 – 4 5 8 9
4589