Titanium(IV) complexes of the crystallographically characterised fluorene-Schiff base N-2-fluorenyl (salicylideneimine) and related bi- and tetradentate ligands

Article abstract of DOI:10.1016/S0277-5387(99)00340-X

Schiff base ligands have been prepared by the condensation of 2-aminofluorene with salicylaldehyde (1, flusalH) or 3-methoxy-2-hydroxybenzaldehyde (2, MeOflusalH). Compound 1 reacts with TiCl₄ in a 1:1 stoichiometry to afford [TiCl₃(flusal)] (3) and in a 2:1 ratio to yield [TiCl₄(flusalH)₂] (4). The reaction of excess TiBz₄ with compound 1 results in the isolation of the octahedral Ti(IV) complex [Ti(flusal)₂(flusalaBz)₂] (5). Crystallographic and spectroscopic data for the latter indicate a complex containing two Schiff base ligands present as conventional N,O chelates and a further two ligands in which the C=N function is reduced by the addition of benzyl and hydrogen moieties producing an O-bound species with pendant amine. The single crystal X-ray diffraction structure of compound 1 has been obtained and compared with the published data for compound 5. Similar ligand alkylation to that observed in compound 5 is also achieved by the reaction of organolithium reagents with compounds 1 and 2; the reaction of PhLi and compound 2 followed by aqueous hydrolysis affords MeOflusalaPhH (6). Although reactivity does occur between TiCl₄ and compound 6, the products could not be fully characterised. Thus tetradentate reduced Schiff base ligands were synthesised by the reaction of salenH₂ with MeLi or PhLi, giving salenaMe₂H₂ (7) and salenaPh₂H₂ (8), respectively. Reaction of compound 8 and TiCl₄ affords the quadruply deprotonated amido complex [Ti(salenamidoPh₂)] (9), which hydrolyses in air to the μ-oxo amine complex [Ti(salenaPh₂)O] (10). (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(99)00340-X

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 177–183
Titanium(IV) complexes of the crystallographically characterised
fluorene-Schiff base N-2-fluorenyl(salicylideneimine) and related
bi- and tetradentate ligands
b
Simon J. Coles a, Michael B. Hursthouse a, David G. Kelly b, , Andrew J. Toner
*
a Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK
b Department of Chemistry and Materials, The Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK
Received 23 August 1999; accepted 4 November 1999
Abstract
Schiff base ligands have been prepared by the condensation of 2-aminofluorene with salicylaldehyde (1, flusalH) or 3-methoxy-2-
hydroxybenzaldehyde (2, MeOflusalH). Compound 1 reacts with TiCl4 in a 1:1 stoichiometry to afford [TiCl3(flusal)] (3) and in a 2:1 ratio
to yield [TiCl4(flusalH)2] (4). The reaction of excess TiBz4 with compound 1 results in the isolation of the octahedral Ti(IV) complex
[Ti(flusal)2(flusalaBz)2] (5). Crystallographic and spectroscopic data for the latter indicate a complex containing two Schiff base ligands
present as conventional N,O chelates and a further two ligands in which the C_N function is reduced by the addition of benzyl and hydrogen
moieties producing an O-bound species with pendant amine. The single crystal X-ray diffraction structure of compound 1 has been obtained
and compared with the published data for compound 5. Similar ligand alkylation to that observed in compound 5 is also achieved by the
reaction of organolithium reagents with compounds 1 and 2; the reaction of PhLi and compound 2 followed by aqueous hydrolysis affords
MeOflusalaPhH (6). Although reactivity does occur between TiCl4 and compound 6, the products could not be fully characterised. Thus
tetradentate reduced Schiff base ligands were synthesised by the reaction of salenH2 with MeLi or PhLi, giving salenaMe2H2 (7) and
salenaPh2H2 (8), respectively. Reaction of compound 8 and TiCl4 affords the quadruply deprotonated amido complex [Ti(salenamidoPh2)]
(9), which hydrolyses in air to the m-oxo amine complex [Ti(salenaPh2)O] (10).
q2000 Elsevier Science Ltd All rights reserved.
Keywords: Additions; Alkylation; Insertions; Nucleophilic; Schiff bases; Titanium
1. Introduction
formed by metal vapour deposition (MVD) methods [16].
In the present work the relative coordination affinities of
Schiff base and fluorenyl moieties contained within poten-
tially chelating ligands are assessed. Part of this work has
previously been the subject of a brief communication [17].
The recent interest in group 4 complexes incorporating the
fluorenyl ligand stems from the discovery that ansa-metal-
locene zirconium complexes containing linked fluorenyl-
cyclopentadienyl ligands are involved in the syndiospecific
polymerisation of a-olefins [1–11]. Examples of unsup-
ported fluorenyl coordination to group 4 metals are far less
numerous than the corresponding indenyl and cyclopenta-
dienyl moieties [12]; the preparation of [(h5-C13H9)2-
TiCl2], from sodium fluorenyl and titanium(IV) chloride,
and of [(h5-C13H9)(h5-C5H5)TiCl2], from thallium flu-
orenyl and [CpTiCl3], are the only examplesoftitanium(IV)
metallocene precursors containing the fluorenyl moiety
[13,14], although a large number of monodithiocarbamate
derivatives have been synthesised from [(h5-C13H9)2TiCl2]
[15]. Recently bis-fluorenyltitanium(0) has also been
2. Results and discussion
2.1. Titanium(IV) complexes of flusalH and derivatives
Schiff base ligands can be readily formed by the conden-
sation of 2-aminofluorene and salicylaldehyde (1, flusalH)
or 3-methoxy-2-hydroxybenzaldehyde (2, MeOflusalH)
(Table 1). The synthetic route, outlined in Scheme 1, is
conventional and employs published methods [18].
Although compounds 1 and 2 appear visually very different
in colour, visible reflectance spectra display similar features,
with a shift in absorbance to higher wavelength occurring as
* Corresponding author. Tel: q44-161-247-1425; fax: q44-161-247-
6357; e-mail: d.g.kelly@mmu.ac.uk
0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved.
PII S0277-5387(99)00340-X
Monday Feb 21 09:38 AM
StyleTag -- Journal: POLY (Polyhedron) Article: 3293

178
S.J. Coles et al. / Polyhedron 19 (2000) 177–183
Table 1
Analytical and spectroscopic data for compounds 1–10
Compound
Colour Yield (%) 1H NMR (d, ppm)
IR a (cmy1
)
Elemental analysis
HC_N
HCR–NH n(C_N) n(N–H)
C
H
N
Cl
FlusalH (1)
yellow 80
orange 75
8.70
8.71
insoluble
insoluble
8.75
1618
1618
1612
1620 b
84.6 (84.2) 5.2 (5.3) 4.9 (4.9)
80.0 (80.0) 5.8 (5.4) 4.4 (4.4)
54.4 (54.7) 3.5 (3.2) 3.1 (3.2) 23.7 (24.3)
62.6 (63.0) 4.6 (4.4) 3.7 (3.4) 17.8 (17.4)
MeOflusalH (2)
TiCl3(flusal) (3)
TiCl4(flusalH)2 (4)
[Ti(flusal)2(flusalaBz)2] (5) orange 25
MeOflusalaPhH (6)
SalenaMe2H2 (7)
SalenaPh2H2 (8)
[Ti(salenamidoPh2)] (9)
[Ti(salenaPh2)O] (10)
red
red
95
99
4.10
3.95
3.88
3.88
1612
3376, 3389 82.2 (82.5) 5.6 (5.3) 3.8 (4.1)
cream 96
3414, 3475 82.7 (82.4) 6.3 (5.9) 3.2 (3.6)
3299 72.1 (72.0) 8.2 (8.0) 9.2 (9.3)
3303 80.0 (79.2) 6.8 (6.6) 6.2 (6.6)
70.4 (71.8) 5.8 (5.1) 6.0 (6.0)
white
white
45
80
brown 90
yellow 93
not obsvd. Abs
c
insoluble
3255, 3374 69.2 (69.2) 5.4 (5.4) 5.6 (5.8)
a Nujol mull.
b Also C_O 1645 cmy1
.
c Also Ti–O 756 cmy1
.
Scheme 1. Synthesis and reactivity of compounds 1 and 2.
Monday Feb 21 09:38 AM
StyleTag -- Journal: POLY (Polyhedron) Article: 3293

S.J. Coles et al. / Polyhedron 19 (2000) 177–183
179
a consequence of the electron donating methoxy substituent
in compound 2 (Fig. 1). Considering the coordination poten-
tial of compounds 1 and 2, it is of note that the pKa of fluorene
is significantly larger than that of indene or cyclopentadiene
[19]. Moreover, the extended delocalisation of chargewithin
the deprotonated fluorene results in far lower coordination
affinities than either indenyl or cyclopentadienyl moieties.
Thus, the stoichiometric reaction of titanium(IV) chloride
and compound 1 in dichloromethane yields the deep redcom-
plex [TiCl3(flusal)] (3), which on the basis of IR evidence
displays ligand bonding through the Schiff base moiety by
chelation of nitrogen and the deprotonated oxygen centre.
The significant change in colour from compound 1 to com-
pound 3 is common in Schiff base systems and doesnot imply
more complex interactions or processes (Fig. 1). Although
the formation of compound 3 is entirely normal, it is of note
that compound 3 is nominally five coordinate . The fact that
this compound strongly retains solvent, and affords an insol-
uble high melting solid once dried, suggests six coordinate
geometry is achieved by the formation of halide bridged
dimers. Molecular weight measurements for related 1:1 com-
plexes have been indicative of such behaviour[20]. Reaction
of titanium(IV) chloride with two equivalents of compound
1 in tetrahydrofuran (THF) yields a red sticky andintractable
solid which retainssolvent. Aftersuspensionindry,deaerated
acetone, [TiCl4(flusalH)2]P(Me)2CO (4) is isolated as a
free-flowing powder from which acetone is not liberatedeven
at elevated temperatures in vacuo. The insolubility of com-
pound 4 limits the extent of its characterisation (Table 1);
however, the various forms of Schiff base denticity and
deprotonation have been explored in detail for both tita-
nium(IV) and zirconium(IV)[20–24]. Byanalogywiththis
work it is possible to suggest that compound 4 exists as a six
coordinate complex containing N-bound ligands in which
acetone hydrogen bonds to the phenolic protons of the pen-
dant OH functionalities. It is the presence of the latter and
their interactions with solvents which are likely to cause the
difficulties in handling and drying the complex [25–27].
Complexes 3 and 4 are typical Schiff base complexes in
which the fluorenyl moiety is entirely passive. To induce
reactivity at this centre, interaction with organometallic rea-
gents was examined. Since considerable problems are asso-
ciated with the alkylation of group 4 Schiff base complexes
using alkyllithiumandGrignardreagents[28,29],compound
1 was reacted directly with TiBz4 [17]. Thus, the addition of
compound 1 to a hexane solution of TiBz4 (1:1.2) at y208C
affords, after work-up, the complex [Ti(flusal)2(flusala-
Fig. 1. Diffuse reflectance visible spectra of compounds 1–5.
evidence for reactivity at the fluorene moiety. However, these
extended aromatic systems do appear to influence the overall
structure; p–p interaction of the fluorene groups of the two
reduced ligands inducing a cis orientation of the monodentate
donors.
A mechanistic appreciation of the formation of compound
5 is difficult to obtain, although several groups have consid-
ered the reactivity of systems containingalkylfunctionalities,
Schiff base ligands and group(4) metals [28–32]. Although
direct interaction of metal and alkyl groups can occur, reac-
tivity is complicated by the potential for metal reductionand/
or nucleophilic attack of the alkyl at the Schiff base C_N
group resulting in amide formation. The isolation of com-
pound 5 extends the latter reactivity, with imine reduction to
amines resulting from the effective addition of benzyl and
hydrogen moieties to the C_N group. It has not proved pos-
sible to follow this process stepwise, although Bz migration
to the coordinate d flusalH ligand followed by intramolecular
proton transfer is clearly realistic. Suchamechanismhasbeen
explored using the reactivity of compounds 1 and 2 with
organolithium reagents.
2.2. Reactivity of organolithium reagents with flusalH and
derivatives
Three equivalents of organolithium reagent are consumed
in the reaction of compound 1 with PhLi or n-BuLi and of
compound 2 with MeLi or t-BuLi. Reaction stoichiometry
suggests that highly air-sensitive intermediates are formed as
a consequence of the deprotonation at hydroxyl and 9-flu-
orenyl protons, and nucleophilic alkyl attack at the imine
centre (Scheme 1). Aqueous hydrolysis protonates all three
basic sites leaving imine reduction by R-addition asthesingle
permanent change. The formation of amines is confirmed in
each reaction by the observation of parent ions in the respec-
tive massspectra, withadditionalcharacterisationoftheprod-
uct obtained from the reaction of compound 2 and PhLi, i.e.
MeOflusalaPhH (6) (Table 1). Since reducing the reaction
stoichiometry to a 2:1 RLi/ligand ratioresultsinthecomplete
recovery of compounds 1 and 2, it can be assumed that the
relative pKa of the three acidic sites is OH-9-fluorenyl
1
Bz2)2] (5) (Scheme 1). H NMR data are consistent with
the crystallographic characterisation of the complex [17],
which indicates the presence of two chelating flusal ligands
in the octahedral titanium(IV) coordination sphere. The
remaining sites are occupied by reduced Schiff base ligands,
reduction having occurred as a consequence of benzyl and
hydrogen addition to the C_N moieties to afford pendant
amine functions. IR data are also consistent with amine and
imine absorbances being observed. Once again there is no
Monday Feb 21 09:38 AM
StyleTag -- Journal: POLY (Polyhedron) Article: 3293

180
S.J. Coles et al. / Polyhedron 19 (2000) 177–183
Scheme 2. Synthesis and reactivity of compounds 7 and 8.
-HC_N. This view is supported by the reactivity observed
between compound 1 or 2 and Li[N(SiMe3)2]. Addition of
excess Li[N(SiMe3)2], followed by hydrolysis, results in
the quantitative recovery of compounds 1 and 2. Although
steric control cannot be ignored, this behaviour suggests that
this less basic reagent is not capable of nucleophilic attack at
the imine moiety.
The reactivity of compounds 1 and 2 with organolithium
reagents demonstrates the general principle that nucleophilic
alkyl attack at the imine function, followed by protonation,
can afford amines. However, clear differences in selectivity
are apparent. The 1:1.21/TiBz4 reactionstoichiometrywhich
affords compound 5 provides an excess of alkylating agent,
but titanium coordination and stoichiometric availability of
phenolic protons moderate reactivity. As a consequence, it
can be proposed that the initial N,O coordination of the Schiff
base ligand enhances intramolecular nucleophilic attack of
the Bz moiety and facilitates intramolecular proton transfer.
That imine alkylation remains marginal is demonstrated by
the 50:50 ratio of amine and imine moieties in compound 5.
However, it is evident that in the formation of compound 5
imine reactivity is preferred to that of the fluorene function,
a clear contrast to the reactivity observed with organolithium
reagents.
terisable product, quadradentate reduced Schiff base ligands
were prepared by the reaction of salenH2 with organolithium
reagents.
2.3. Synthesis and reactivity of reduced salenH2 ligands
In an analogous manner to the reaction of flusalH and
organolithium reagents, the reaction of MeLi or PhLi, fol-
lowed by aqueous hydrolysis, affords salenaMe2H2 (7) and
salenaPh2H2 (8), respectively (Scheme 2). Stoichiometric
reaction of compound 8 and TiCl4 in the presence of NEt3
results in complete deprotonation of the N2O2 donor set and
the isolation of [Ti(salenamidoPh2)] (9). Similar tetra-
anionic species have been synthesised using reduced Schiff
base ligands and zirconium(IV) [34]. In the latter, the octa-
hedral geometry is completed by pyridine coordination.
Although compound 9 is nominally four coordinate, the clas-
sical octahedral geometry may be completed by intermole-
cular dative bonding by the oxygen centres. Such behaviour
is well established in the corresponding titanium Schiff base
chemistry [31,32,35,36]. Compound 9 is unstable in moist
air, undergoing rapid hydrolysis to the polymeric m-oxo
diamine complex [Ti(salenaPh2)O] (10). Once again the
relative stabilityofsuchm-oxospecieshasbeendemonstrated
by the formation of a number of dimeric, oligomeric and
polymeric complexes in which the m-oxo group is readily
identified by a strong n(Ti–O) IR vibration [32,37,38].
The reactivity of compound 6 and TiCl4 also provides a
useful contrast to the formation of compound 5. It is apparent
that reactivity occurs between compound 6 and TiCl4; how-
ever, the insolubility of the products precludes the separation
and characterisation of what appears to be several metal-
containing complexes. The elimination of HCl from the reac-
tion TiCl4 with ammine and amine ligandsis wellestablished,
and such reactivity may be the source of multiple products
here [33]. To increase the potential to form a single charac-
2.4. Crystallographic characterisation of N-2-fluorenyl-
(salicylideneimine) (1)
Crystallographic characterisation of N-2-fluorenyl-
(salicylideneimine) allows direct structural comparisonwith
Monday Feb 21 09:38 AM
StyleTag -- Journal: POLY (Polyhedron) Article: 3293

S.J. Coles et al. / Polyhedron 19 (2000) 177–183
181
the titanium complex 5. Structural elucidation of compound
1 indicates similarities with the bond lengths and angles that
are observed in single crystal X-ray diffraction studies of the
fluorene and simple Schiff base ligands such as salenH2
[39,40], Fig. 2. Comparison of geometries in the deproton-
ated flusal and reduced flusala ligands of compound 5 with
compound 1 demonstrates the effects of both coordination
and reduction (Table 2). The imine flusalH bond, N(1)–
C(14), is slightly elongated in the coordinate d Schiff base
of compound 5, although it must be noted that the
O(1)∆H∆N(1) hydrogen bond of flusalH is replaced by
metal coordination in compound 5. Thus, the relatively mod-
est elongation on titanium coordination must be viewed in
the context of substituting one Lewis acid interaction atN(1)
with another. More significantly, lengthening of the same
bond occurs by reduction in the pendant amine of the same
complex — clearly a direct consequence of changing bond
order. The corresponding nitrogen–fluorene linkages, N(1)–
C(12), shorten in both metal-bound forms. Perhaps most
notably, little change in the C(12)–N(1)–C(14) bond angle
occurs between the hydrogen bonded free Schiff base and the
reduced flusala moiety of compound 5, despite the change
from sp2 to sp3 hybridisation. In contrast, the coordinated
imine moiety displays a shift towardssp character—afeature
which may optimise a Ti(dp)–N(pp) interaction. Moreo-
ver, the significant structural changes which occur on coor-
dination help to rationalise the differing functional group
selectivity observed for the reactivity of RLi or TiBz4 with
compound 1.
Fig. 2. Single crystal X-ray structure of compound 1.
Table 2
Bond lengths and angles in 1 and 5
Molecular dimensions
1
5 a
Flusal moiety
Flusala moiety
˚
Bond lengths (A)
N(1)–C(12)
N(1)–C(14)
C(14)–C(15)
O(1)–C(16)
O(1)–H
1.469(5)
1.272(5)
1.449(5)
1.362(4)
0.820(1)
1.805(4)
2.528(4)
1.409(10)
1.317(10)
1.419(11)
1.318(10)
1.379(12)
1.449(10)
1.507(11)
1.370(9)
N(1)–H
O(1)–N(1)
Bond angles (8)
C(13)–C(12)–N(1)
C(12)–N(1)–C(14)
C(14)–C(15)–C(16)
C(15)–C(16)–O(1)
O(1)–H–N(1)
113.9(5)
119.3(4)
120.6(4)
122.0(4)
146.2(2)
120.9(9)
128.7(9)
121.7(10)
119.7(10)
119.3(11)
118.8(8)
114.2(8)
115.3(9)
a From [17].
Crystal data for C18H15NO (1): Ms285.33; monoclinic;
space group P21a, as11.048(42), bs7.936(15), cs
3
˚
˚
3. Conclusion
15.899(35) A; bs97.39(8)8; U-1478.3(6) A ; Dcs
1.371 g cmy3; Zs4; Ts145(2) K; ms0.084 mmy1
;
Titanium(IV) complexes containing Schiff base ligands
and their reduced analogues may be synthesised by direct
reaction of metal salt and ligand. More complex reactivity
occurs between Schiff base ligands and the organotitanium
reagent TiBz4, involving partial imine alkylation and reduc-
tion. Reduced ligands can react with TiCl4 to afford amido
functionalities, which may themselves be hydrolysed to
regenerate coordinate d amines. Thus by manipulation of
reagents and conditions a range of ligand-centred transfor-
mations involving imine, amine and amido functionalities
may occur within the group 4 metal coordination sphere.
F(000)s600; l(Mo Ka)s0.71069 nm; 2.58-u-25.07;
total observed reflectionss2124; observed reflections
[I)2s(I)] 734; Rs0.0489; Rws0.0958 (observed data).
4.2. Data collection and structure solution
Collection, FAST TV area detector; absorption correction,
DIFFABS (min./max. factors 0.748 and 1.324, respec-
tively); solution, direct methods (SHELXS-86); refinement,
full matrix least squares on F2 (SHELX-92), non-hydrogen
atoms anisotropic, hydrogen atoms riding.
4.3. Synthetic procedures
4. Experimental
4.1. Crystallographic characterisation
Solvents were dried using standard methods. All titanium
reactions were performed under nitrogen [32]. RLi reagents
[RsMe, Ph, n-Bu, t-Bu, N(SiMe3)2] were purchased from
Aldrich. 2-Aminofluorene, lithiumfluorenyl and TiBz4, were
Recrystallisation of compound 1 from THF–Et2O using
vapour diffusion techniques gave yellow-brown crystals
(0.07=0.07=0.11 mm) suitable for single crystal X-ray
analysis. Data collection and structure solution of compound
1 was performed using previously described methods, result-
ing in the following crystal data [41–44].
1
prepared using published methods [18,45–47]. H NMR
spectra were obtained at 270 MHz in CDCl3 unless stated
otherwise. Elemental analysis and important characterisation
data are given in Table 1.
Monday Feb 21 09:38 AM
StyleTag -- Journal: POLY (Polyhedron) Article: 3293

182
S.J. Coles et al. / Polyhedron 19 (2000) 177–183
4.3.1. N-2-Fluorenyl(salicylideneimine), flusalH (1)
NMR:d 3.22 (m, 4H, PhCH2CHNH), 3.72(s, 2H, 9-fluorene
CH2), 3.96 (s, 2H, 9-fluorene CH2), 4.18 (s, 2H,
PhCH2CHNH), 4.60 (m, 2H, PhCH2CHNH), 6.67–7.86 (m,
54H, aromatic), 8.75 (s, 2H, CH). FABq MS: m/z 268
(100%, [1]q), 1368 (10%, [5]q). IR (Nujol) (cmy1):
n(C_N) 1612(s), n(N–H) 3376(s), 3389(s).
The ligand was prepared by the dropwise addition of one
equivalentof2-aminofluoreneinTHFtoanethanolicsolution
of freshly distilled salicylaldehyde. After refluxing for 1 h the
solution was cooled to afford crude compound 1, which was
washed in Et2O and dried in vacuo. Recrystallisation of the
crude material from ethanol–chloroform gave compound 1
as a yellow-brown crystalline solid (80%). 1H NMR: d 3.95
(s, 2H, CH2), 6.92–7.84 (m, 11H, aromatic), 8.70 (s, 1H,
CH), 13.30 (s, 1H, OH). EIq MS: m/z 285 (100%, [1]q).
IR (Nujol) (cmy1): n(C_N) 1618, n(O–H) 3460.
4.3.6. N-2-Fluorenyl(a-phenyl-3-methoxysalicylidene-
amine) (6)
Compound 2 (3.0 g, 9.5 mmol) in THF (approx. 40 cm3)
was cooled to y208C and PhLi (1.8 M, 15.9 cm3, 28.6
mmol) was added dropwise. During addition the solution
developed a deep red colour. After stirring for 1 h, deaerated
distilled water was added. The mixture was diluted with Et2O
and the organic layer was separated. The aqueous layer was
shaken with two portions of Et2O (approx. 2=30 cm3) and
the combined organic fractions were dried over magnesium
sulfate. Following filtration the solvent was removed under
reduced pressure to yield crude compound 6 (3.7 g, f96%)
as a gelatinous, off-white solid. Recrystallisation from THF–
Et2O afforded cream, crystalline material. 1H NMR: d 1.18
(s br, 1H, NH), 3.68 (s, 2H, CH2), 3.83 (s, 3H, CH3O), 4.40
(s br, 1H, OH), 5.82 (s, 1H, CH), 6.73–6.83, 7.07–7.35 (m,
Ph). FABq MS: m/z 393 (55%, [6]q). IR (Nujol)(cmy1):
n(N–H) 3414, 3475 (vs), n(O–H) 1375.
4.3.2. N-2-Fluorenyl(3-methoxysalicylideneimine) (2)
Compound 2 was prepared by the same method as com-
pound 1 and recrystallised from ethanol (75% yield). H
NMR (CDCl3): d 3.94 (s, 3H, MeO) and (s, 2H, CH2)
(methylene protons obscured by the methoxy resonance),
6.84–7.83 (m, 11H, Ph), 8.71 (s, 1H, CH), 13.83 (s, 1H,
OH). EIq MS: m/z 316 (100%, [2qH]q). IR (Nujol)
(cmy1): n(C_N) 1618, n(O–H) 3460.
1
4.3.3. [TiCl3(flusal)] (3)
A toluene solution of titanium(IV) chloride (1.0 M, 3.15
cm3, 3.15 mmol) was added dropwise to compound 1 (0.9
g, 3.2 mmol) in CH2Cl2 (approx. 30 cm3). A deep red pre-
cipitate immediately formed. The solution was refluxed for 1
h, after which the solid was separated by filtration, washed
with hexane (5=10 cm3) and dried in vacuo to afford com-
pound 3 as a maroon free-flowing solid. Yield: 1.3 g (95%).
Compound 3 is insufficiently soluble to obtain 1H NMR spec-
troscopic data. FABq MS: m/z 437 (15%, [3]q). M.p. dec.:
306–3108C.
Similar reactions carried out using compounds 1 and 2
with other organolithium reagents afforded products analo-
gous to compound 6. These products did not lend themselves
1
to crystallisation and thus produced H NMR spectra con-
taining residual solvent, and tolerable but somewhat variable
elemental analysis. However, molecular ions of significant
intensity could be recorded in each case. Thus N-2-flu-
orenyl(a-phenyl-salicylideneamine) [EI MS: m/z 363,
85%] and N-2-fluorenyl(a-n-butyl-salicylideneamine)
[FABq MS: m/z 344, 100%] were recovered from the reac-
tion of compound 1 with phenyllithium and butyllithium,
respectively. The methoxyl derivatives N-2-fluorenyl(a-
methyl-3-methoxysalicylideneamine) [FABq MS:m/z331,
20%] and N-2-fluorenyl(a-t-butyl-3-methoxysalicylidene-
amine) [FABq MS: m/z 374, 100%] were alsoisolatedfrom
the reaction of compound 2 with methyllithium and
t-butyllithium.
4.3.4. [TiCl4(flusalH)2] (4)
Compound 1 (2.0 g 7.0 mmol) in THF (approx. 50 cm3)
was treated with titanium(IV) chloride (1.0 M, 3.5 cm3, 3.5
mmol). A deep red solid precipitated, after whichthesolution
wasrefluxed for 1 h. Thecolourlesssolventwasthendecanted
from the solid which was washed with THF (2=30 cm3),
also resulting in colourless extracts. The solid was slurried in
acetone and cooled to y208C. After 1 day, decantation of
the solvent and drying in vacuo gave 2.8 g of [TiCl4-
(flusalH)2]PMe2CO (4) as a deep red, air-stable solid in
1
quantitative yield. Insolubility precluded H NMR spectro-
scopic characterisation. FABq MS: m/z 286 (100%,
[1qHq]), 348 (40%, [Ti(_O)(flusal)]q). IR (Nujol)
(cmy1): n(C_O) 1645, n(C_N) 1620, n(O–H) 3361.
4.3.7. N,N9-(1,2-Ethlyenebis(a-methylsalicylaldamine)](7)
An ET2O solution of methyllithium (1.4 M, 21.3 cm3, 29.9
mmol) was added dropwise to a THF solution of salenH2
(2.0 g, 7.46 mmol) at y208C. The resultant colourless solu-
tion was stirred for 1 h before deaerated, distilled water was
added (approx. 20 cm3). Addition of Et2O produced two
layers. After separation, the aqueous layer was washed with
ether (3=30 cm3). The combined organic phases were con-
centrated, dried with MgSO4 and further reduced to produce
a paste which was recrystallised from THF–Et2O to afford
4.3.5. [Ti(flusal)2(flusalaBz2)2] (5)
Compound 1 (0.50 g, 1.8 mmol) was added in a single
portion to a hexane solution (20 cm3) of TiBz4 (0.87 g, 2.1
mmol) at y208C. The dark brown precipitate which formed
over 0.5 h was filtered, washed with hexane and extracted
with toluene. The resultant brown solution becomes progres-
sively pale orange. Addition of hexane and storage at y20oC
affords toluene solvated compound 5 over about 3 days. 1H
1
compound 7 (1.0 g, 45%). H NMR (CD2Cl2): d 1.38 (s,
3H, Me), 1.41 (s, 3H, Me), 1.53 (b s, NH), 2.66 (m, 2H,
Monday Feb 21 09:38 AM
StyleTag -- Journal: POLY (Polyhedron) Article: 3293

S.J. Coles et al. / Polyhedron 19 (2000) 177–183
183
[10] G.S. Herrmann, H.G. Alt, M.D. Rausch, J. Organomet. Chem. 401
(1991) C5.
[11] N.G. Alt, W. Milius, S.J. Palackal, J. Organomet. Chem. 472 (1994)
113.
CH2), 2.79 (m, 2H, CH2), 3.88 (q, 2H, CH), 6.70–7.13 (m,
8H, Ph), 11.03 (bs OH). EI MS: m/z 300 (100%, [7]q).
4.3.8. N,N9-(1,2-Ethylenebis(a-phenylsalicylaldamine)](8)
The compound was prepared by the same route as com-
pound 7, giving a white solid in 80% yield. 1H NMR: d 1.42
(b s, NH), 2.93 (m, 4H, CH2), 4.88 (s, 2H, CH), 6.72–7.31
(m, 18H, Ph), 11.50 (bs OH). FABq MS: m/z 425 (30%,
[8]q).
[12] E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.), Comprehensive
Organometallic Chemistry II, vol. 4, Pergamon, Oxford, 1995, Chap-
ter 5.
[13] E. Samuel, R. Seltan, J. Organomet. Chem. 4 (1965) 156.
[14] A.K. Sharma, N.K. Kaushik, Acta Chim. Hung. 116 (1984) 361.
[15] N.K. Kaushik, A.K. Sharma, G.S. Sodhi, Indian J. Chem. 20 (1981)
847.
[16] F.G.N. Cloke, A.R. Dias, A.M. Galvao, J.L.F. daSilva, J. Organomet.
Chem. 548 (1997) 177.
[17] S.J. Coles, M.B. Hursthouse, D.G. Kelly, A.J. Toner, N.M. Walker,
Can. J. Chem. (in press).
4.3.9. [Ti(salenamidoPh2)] (9)
A toluene solution of compound 8 (1.76 g, 4.15 mmol)
and triethylamine (3.5 cm3, 25 mmol) was treated dropwise
with TiCl4 (1.0 M toluene, 4.15 cm3, 4.15 mmol). After
stirring for 12 h, an orange solution was filtered from the
precipitated [NEt3H]Cl, and after concentrationandaddition
of hexane afforded compound 9 as a brown crystalline solid
(1.8 g, 90%). FABq MS: m/z 468 (50%, [9]q).
[18] W.E. Kuhn, Org. Synth. 13 (1933) 447.
[19] W.K. McEwen, J. Am. Chem. Soc. 58 (1936) 1124.
ˆ
[20] J.A. Garcia-Vasquez, M. Lupez-Becerra, J.R. Masaguer, Transition
Metal Chem. 8 (1983) 233.
[21] N.S. Biradar, V.H. Kulkarni, J. Inorg. Nucl. Chem. 33 (1971) 3847.
[22] F.L. Bowden, D. Ferguson, J. Chem. Soc., Dalton Trans. (1974) 460.
[23] S.J. Coles, M.B. Hursthouse, D.G. Kelly, A.J. Toner, N.M. Walker,
J. Chem. Soc., Dalton Trans. (1998) 3489.
[24] F. Corazza, E. Solari, C. Floriani, A. Chiesi-Villa, C. Guastini, J.
Chem. Soc., Dalton Trans. (1990) 1335.
[25] A.D. Garnovskii, A.L. Nivorozhkin, V.L. Minkin, Coord. Chem. Rev.
126 (1993) 1.
[26] S. Yamada, Coord. Chem. Rev. 1 (1966) 415.
[27] U. Casellata, P.A. Vigato, M. Vidali, Coord. Chem. Rev. 23 (1977)
31.
[28] C. Floriani, E. Solari, F. Corazza, A. Chiesi-Villa, C. Guastini,Angew.
Chem., Int. Ed. Engl. 28 (1989) 64.
4.3.10. [Ti(salenaPh2)O] (10)
An orange toluene solution of compound 9 (1.0 g, 2.14
mmol) was filtered in air and rapidly formed a pale yellow
precipitate. After 0.5 h the precipitate was filteredandwashed
with dry hexane to afford compound 10 (1.8 g, 93%). Com-
pound 10 could be crystallised from CH2Cl2–Et2O as an ana-
lytically pure microcrystalline solid. FABq MS: m/z 955
(100%, [102yO]q).
[29] E. Solari, C. Floriani, A. Chiesi-Villa, C. Rizzoli, J. Chem. Soc.,
Dalton Trans. (1992) 367.
[30] E.B. Tjaden, D.C. Swenson, R.F. Jordan, J.L. Petersen, Organome-
tallics 14 (1995) 371.
5. Supplementary data
[31] S.J. Coles, M.B. Hursthouse, D.G. Kelly, A.J. Toner, N.M. Walker,
Polyhedron 15 (1996) 4307.
[32] S.J. Coles, M.B. Hursthouse, D.G. Kelly, A.J. Toner, N.M. Walker,
J. Organomet. Chem. 580 (1999) 304.
[33] A.D. Norman, Inorganic Reactions and Methods, vol. 8, VCH, New
York, 1991, p. 80.
[34] P. Woodman, P.B. Hitchcock, P. Scott, J. Chem. Soc., Chem. Com-
mun. (1996) 2735.
[35] M. Mazzanti, S. Gambarotta, C. Floriani, A. Chiesi-Villa, C. Guatini,
Inorg. Chem. 25 (1986) 2308.
Crystallographic data for the structural analyses have been
deposited with the Cambridge Crystallographic Data Centre,
CCDC, No. 127639. Copies of this information can be
obtained free of charge from The Director, CCDC, 12, Union
Road, Cambridge CB2 1EZ (fax: q44-1223-336-033; e-
mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.
ac.uk).
[36] J.-M. Rosset, C. Floriani, M. Mazzanti, A. Chiesi-Villa, C. Guatini,
Inorg. Chem. 29 (1990) 3991.
[37] K. Nakajima, C. Sasaki, M. Kojima, T. Aoyama, S. Ohba, Y. Saito,
J. Fujita, Chem. Lett. (1987) 2189.
[38] E. Gallo, E. Solari, F. Franceschi, C. Floriani, A. Chiesi-Villa, C.
Rizzoli, Inorg. Chem. 34 (1995) 2495.
[39] G.M. Brown, M.H. Bortner, Acta Crystallogr. 7 (1954) 139.
[40] N. Bresciani-Pahor, M. Calligaris, G. Nardin, L. Randaccio, Acta
Crystallogr., Sect. B 34 (1978) 1360.
[41] J.A. Darr, S.R. Drake, M.B. Hursthouse, K.M.A. Malik, Inorg. Chem.
32 (1993) 5704.
References
[1] J.A. Ewen, R.L. Jones, A. Razavi, J.D. Ferrara, J. Am. Chem. Soc.
110 (1988) 6255.
[2] J.A. Ewen, M.J. Elder, R.L. Jones, L. Haspeslagh, J.L. Atwood, S.G.
Bott, K. Robinson, Makromol. Chem., Makromol. Symp. 48/49
(1991) 235.
[3] J.A. Ewen, M.J. Elder, Makromol. Chem., Makromol. Symp. 66
(1993) 179.
[42] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
¨
[43] G.M. Sheldrick, SHELX-93, UniversityofGottingen,Germany,1993.
[4] A. Razavi, J.D. Ferrara, J. Organomet. Chem. 435 (1992) 299.
[5] A. Razavi, U. Thewalt, J. Organomet. Chem. 445 (1993) 111.
[6] A. Razavi, J.L. Atwood, J. Organomet. Chem. 459 (1993) 117.
[7] B. Rieger, J. Organomet. Chem. 420 (1991) C17.
[8] B. Rieger, M. Steinmann, R. Fawzi, Chem. Ber. 125 (1993) 2373.
[9] M. Bochmann, S.J. Lancaster, M.B. Hursthouse, M. Mazid, Organo-
metallics 12 (1993) 4718.
[44] N.P.C. Walker, D. Stuart, Acta Crystallogr. Sect. A39 (1983) 158
(adapted for FAST geometry by A. Karaulov, University of Wales,
Cardiff, 1991).
[45]
G.W.H. Scherf, R.K. Brown, Can. J. Chem. 38 (1960) 2450.
[46] U. Zucchini, E. Albizzati, U. Giannini, J. Organomet. Chem. 26
(1971) 357.
[47] J.J. Felten, W.P. Anderson, J. Organomet. Chem. 36 (1972) 87.
Monday Feb 21 09:38 AM
StyleTag -- Journal: POLY (Polyhedron) Article: 3293