Synthesis and structures of ferrocenyl-substituted salicylaldiminato complexes of magnesium, titanium and zirconium

Article abstract of DOI:10.1016/j.poly.2005.07.012

N-ferrocenyl salicylaldimine (FcPI)H, readily accessible from aminoferrocene and salicylaldehyde, reacts with dibutylmagnesium in THF to afford a red crystalline (FcPI)₂Mg(THF)₂ (2). The reactions of the Li(FcPI) with CpTiCl₃ gave CpTiCl₂(FcPI) · CH₂Cl₂ (4), whereas with CpZrCl₃ · DME a mixture of three products is formed: CpZrCl(FcPI)₂ (5), CpZrCl₂(FcPI) (6), and (FcPI)₂ZrCl₂ · CH₂Cl₂ (3 · CH₂Cl₂). The crystal structures of compounds 2-6 are reported. Typically, the N-O chelates are oriented such that O donors are mutually trans, while N donors prefer to be trans to Cl ligands. The redox potentials of these complexes are very similar to ferrocene. On activation with methylaluminoxane, the Ti complex 4 shows moderate activity for ethylene polymerisation, while (FcPI) ₂ZrCl₂ is highly active for the oligomerisation of ethylene, to give products with average degrees of polymerisation of 12-16.

Full text of DOI:10.1016/j.poly.2005.07.012

Polyhedron 25 (2006) 387–396
www.elsevier.com/locate/poly
Synthesis and structures of ferrocenyl-substituted
salicylaldiminato complexes of magnesium, titanium and zirconium
Robyn K.J. Bott, Mark Schormann, David L. Hughes,
*
*
Simon J. Lancaster , Manfred Bochmann
Wolfson Materials and Catalysis Centre, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
Received 6 July 2005; accepted 6 July 2005
Available online 18 August 2005
Dedicated to Professor Malcolm Chisholm on the occasion of his 60th birthday
Abstract
N-ferrocenyl salicylaldimine (FcPI)H, readily accessible from aminoferrocene and salicylaldehyde, reacts with dibutylmagnesium
in THF to afford a red crystalline (FcPI)2Mg(THF)2 (2). The reactions of the Li(FcPI) with CpTiCl3 gave CpTiCl2(FcPI) Æ CH2Cl2
(4), whereas with CpZrCl3 Æ DME a mixture of three products is formed: CpZrCl(FcPI)2 (5), CpZrCl2(FcPI) (6), and (FcPI)2ZrCl2 Æ
CH2Cl2 (3 Æ CH2Cl2). The crystal structures of compounds 2–6 are reported. Typically, the N–O chelates are oriented such that O
donors are mutually trans, while N donors prefer to be trans to Cl ligands. The redox potentials of these complexes are very similar
to ferrocene. On activation with methylaluminoxane, the Ti complex 4 shows moderate activity for ethylene polymerisation, while
(FcPI)2ZrCl2 is highly active for the oligomerisation of ethylene, to give products with average degrees of polymerisation of 12–16.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Titanium; Zirconium; Magnesium; Chelate ligands; Ferrocene; Polymerisation catalysis
1. Introduction
vating metal alkyl catalyst precursors electrochemically,
taking advantage of redox active ferrocenyl substituent
in the immediate vicinity of the active metal centre. In
the course of a programme investigating the potential
of new heteroatom chelates in olefin polymerisation
catalysis [9], especially based on N–O ligands of the sal-
icylaldiminato type [10], we became interested in ferr-
ocenyl-substituted derivatives and report here the
syntheses and structures of magnesium, titanium and
zirconium complexes.
Complexes based on ferrocenyl-substituted Schiff-
base ligands have been widely explored, mainly based
on the facile condensation reactions of amines with acyl-
or formylferrocenes [1–3]. Alternatively, ligands derived
from amino- and 1,10-diaminoferrocene [4] can be em-
ployed. For example, Arnold et al. [5,6] reported a num-
ber of amido and tetradentate salen-type ligands in
which the 1,10ferrocenediyl unit is incorporated into
the ligand backbone. A similar family of ligands were re-
ported by Gibson et al. [7,8], including iminopyridines
with pendant ferrocenyl substituents. Applied to group
4 complexes suitable for polymerisation catalysis, such
ligands offer the possibility, at least in principle, of acti-
2. Results and discussion
2.1. Syntheses
*
The ferrocenyl salicylaldimine (FcPI)H (1-H) was
prepared by reaction of 3-tert-butyl salicylaldehyde with
Corresponding author. Tel.: +44 1603 502044.
E-mail address: m.bochmann@uea.ac.uk (M. Bochmann).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.07.012

388
R.K.J. Bott et al. / Polyhedron 25 (2006) 387–396
Fc
aminoferrocene in ethanol over molecular sieves (Eq.
(1)). On concentrating the solution, 1-H was obtained
as a pale-red, microcrystalline powder in 65% yield.
N
O
THF
THF
Fc
Fc
N
MgBu2
THF
Mg
OH
O
N
NH2
2
OH
tBu
EtOH
- H2O
tBu
O
+
Fe
Fe
tBu
1-H
N
OH
ZrCl4
ð1Þ
Na
Fc
The reaction of 1-H with dibutylmagnesium in tetra-
hydrofuran afforded a red crystalline compound, which
was identified as (FcPI)2Mg(THF)2 (2). It had been the
intention to use this magnesium reagent in reactions
with TiCl4 and ZrCl4; however, no clean products could
be isolated from these reactions under a variety of con-
ditions. The treatment of group 4 metal halides with the
lithium salt of 1 proved similarly unsatisfactory, whereas
mixtures of the sodium salt 1-Na with ZrCl4 in tetrahy-
drofuran afforded the bis(N-ferrocenylsalicyliminato)-
zirconium dichloride 3 (Scheme 1).
By contrast, the reaction of 1-Li with CpTiCl3 in
THF proceeded as expected. Extraction of the crude
product with dichloromethane and layering the concen-
trated dichloromethane solution with light petroleum
afforded dark red-brown cubic crystals of CpTiCl2(FcPI) Æ
CH2Cl2 (4).
Fc
N
N
ZrCl4
THF
ZrCl2
2
ONa
3
O
tBu
2
tBu
Scheme 1.
(3 Æ CH2Cl2) (Scheme 2). The latter is identical to the
product from 1-Na and ZrCl4 but was obtained in this
case as the dichloromethane solvate. The formation of
3 evidently results from Cp ligand exchange. The three
products were separated manually and identified by sin-
gle-crystal X-ray diffraction.
2.2. Structural studies
In a similar manner, 1-Li was reacted with CpZrCl3 Æ
DME. However, this reaction led to several products
which co-crystallised from dichloromethane solution:
red-brown cubic crystals of CpZrCl2(FcPI) (5), clusters
of dark red-brown needles of CpZrCl(FcPI)2 (6), and
dark red-brown cubic crystals of (FcPI)2ZrCl2
The magnesium complex 2 has octahedral geometry,
with the salicylato-O atoms in trans and two THF li-
gands in cis-positions (Fig. 1). Selected bond lengths
and angles are collected in Table 1. This contrasts with
Fe
CpTiCl3
THF
Ti
N
O
Cl
Fc
4
Cl
N
OLi
Fe
Cl
Zr
tBu
O
N
O
N
CpZrCl3
THF
Cl
+
Zr
N
THF
Cl
O
Fe
6
5
Fe
Fe
O
N
N
+
Zr
O
Cl
Cl
Fe
3
Scheme 2.

R.K.J. Bott et al. / Polyhedron 25 (2006) 387–396
389
Table 1
˚
Selected bond lengths (A) and angles (ꢁ) for (FcPI)2Mg(THF)2 (2)
Mg–O1
Mg–N
Fe–Cp1
Mg–O3
Fe–Cp2
1.982(4)
2.174(6)
1.632
2.136(5)
1.638
O(1)–Mg–O(10)
O1–Mg–N0
175.5(3)
85.8(2)
97.3(2)
90.6(2)
97.3(2)
85.8(2)
87.7(3)
93.3(3)
171.64(19)
177.9
O1–Mg–N
O(1)–Mg–O(3)
O10–Mg–N0
N–Mg–O10
O(3)–Mg–O(30)
N–Mg–N0
O(3)–Mg–N
Cp1–Fe–Cp2
The prime signifies a symmetry operation about a twofold symmetry
axis. Here, and in all the complexes, the centroid of the substituted Cp
ring of the Fc group is labelled as Cp1, and that of the outer Cp ring as
Cp2.
Fig. 1. Molecular structure of (FcPI)2Mg(THF)2 (2), showing the
structure of (trimethylphenyl)phenoxyimine titanium
monocyclopentadienyl dichloride [10b]. The Ti–Cl bond
length of the chlorine ligand trans to N is significantly
longer than that trans to O. The Ti–Cp (centroid) dis-
atomic numbering scheme with thermal ellipsoids at 30% probability.
a related complex of a tetradentate ferrocenediyl ligand
reported by Arnold et al. [6] (compound A) where the
salicylic O and N atoms are cis to one another in equa-
torial positions, while the THF ligands are trans [\O(3)–
Mg–O(4) = 169.3(2)ꢁ]. The bond distances from the
THF–O atom to magnesium are similar in both com-
˚
tance is 2.053 A, typical for Ti(IV) Cp complexes.
Complex 5 is the zirconium analogue of 4. However,
the larger zirconium also coordinates to one tetrahydro-
furan molecule, to give a complex with a distorted octa-
hedral geometry (Fig. 3). Selected bond lengths and
angles are given in Table 3. Crystals of 5 were of limited
quality (R1 = 0.127). The chlorides are in cis positions
[Cl(1)–Zr–Cl(2) angle 88.5(2)ꢁ] and in the same plane
as the ferrocenyl phenoxyimine, with the cyclopentadie-
nyl ring trans to the tetrahydrofuran [Cp(centroid)–Zr–
O(2) angle 174.2ꢁ]. As was the case with the Ti complex
4, the Zr–Cl(1) bond trans to N is slightly longer than
Zr–Cl(2), although this difference is less pronounced
than in the titanium example.
The mono-chloro complex 6 is also octahedral
(Fig. 4), analogous to but slightly more distorted than
the previously reported bis(N-ethylsalicyliminato) com-
plex CpZrCl(EtPI)2 [10d]. Selected bond lengths and an-
gles are shown in Table 4. One N–O chelate is
equatorially bound, while the Cp ring and the N atom
of the second N–O ligands occupy axial positions. The
oxygen atoms are approximately trans to one another
[\O(1)–Zr–O(2) = 156.1(2)ꢁ]. Steric pressures force the
cis-nitrogen donors closer together, viz. \N(1)–Zr–
N(2) = 74.2(3)ꢁ. This is similar to structures previously
reported and is the expected structural trend for the fa-
voured geometry of zirconium complexes containing
two phenoxy-imine ligands [10,11]. As was the case in
CpZrCl(EtPI)2, the plane of one of the phenoxy-imine
ligands, C(31)–O(2)–Zr–N(2), in complex 6 is almost
parallel to the Cp plane, while the plane of the second
phenoxy-imine, C(17)–N(1)–Zr–O(1), is nearly perpen-
˚
˚
plexes, 2.161(5) and 2.141(4) A in A and 2.136(5) A in
2, as are the Mg–O(anionic) distances (1.974(5) and
˚
˚
1.984(5) A, compared to 1.982(4) A). The Mg–N bonds
in 2 are 2.175(6) A, significantly shorter than in A.
˚
Fe
THF
N
O
N
O
Mg
THF
A
tBu
But
The titanium complex CpTiCl2(FcPI) (4), crystallises
with one molecule of dichloromethane (Fig. 2). Selected
˚
bond lengths (A) and angles (ꢁ) are collected in Table 2.
The five-coordinate titanium resides in a distorted
square-based pyramidal environment, with the cyclo-
pentadienyl ring at the apex and the chlorides cis to each
other. The N–O chelating ligand forms a plane which in-
cludes the phenoxide ring and the –C@N group. This
pattern is similar to that seen in the previously published

390
R.K.J. Bott et al. / Polyhedron 25 (2006) 387–396
35
34
C(31)
33
32
25
Cl(5)
Cl(4)
Ti
24
64
65
21
164
61
N(2)
12
O(1)
11
Fe
161
121
23
22
16
13
62
63
15
163
14
162
Fig. 2. Molecular structure of CpTiCl2(FcPI) (4), showing the atomic numbering scheme. Ellipsoids are drawn at the 50% probability level.
Table 2
Table 3
Selected bond lengths (A) and angles (ꢁ) for (FcPI)CpZrCl2 Æ THF (5)
˚
˚
Selected bond lengths (A) and angles (ꢁ) for (FcPI)TiCpCl2 Æ CH2Cl2
(4 Æ CH2Cl2)
Zr–O(1)
Zr–N
Zr–Cl(1)
Zr–Cl(2)
Zr–Cp
Zr–O(2)
Fe–Cp1
Fe1–Cp2
2.025(13)
2.382(17)
2.496(6)
2.486(6)
2.262
2.391(13)
1.653
1.667
Ti–Cp
2.052
Ti–N(2)
Ti–O(1)
Fe–Cp1
Ti–Cl(4)
Ti–Cl(5)
Fe–Cp2
2.267(2)
1.873(2)
1.659
2.3837(8)
2.3217(7)
1.663
O(1)–Ti–N(2)
O(1)–Ti–Cl(4)
O(1)–Ti–Cl(5)
N(2)–Ti–Cl(4)
N(2)–Ti–Cl(5)
Cp1–Fe–Cp2
Cp–Ti–O(1)
78.76(8)
84.83(6)
132.95(6)
145.13(6)
83.44(5)
174.7
113.9
105.6
109.2
112.7
O(1)–Zr–N
79.4(6)
90.4(4)
154.3(4)
153.8(4)
90.5(4)
76.9(5)
175.6
88.5(2)
102.6
174.2
O(1)–Zr–Cl(1)
O(1)–Zr–Cl(2)
N–Zr–Cl(1)
N–Zr–Cl(2)
O(1)–Zr–O(2)
Cp1–Fe–Cp2
Cl(1)–Zr–Cl(2)
Cp–Zr–O(1)
Cp–Zr–O(2)
Cp–Zr–Cl(1)
Cp–Zr–Cl(2)
Cl(1)–Zr–O(2)
Cl(2)–Zr–O(2)
Cp–Ti–N(2)
Cp–Ti–Cl(4)
Cp–Ti–Cl(5)
Cl(4)–Ti–Cl(5)
85.69(3)
104.3
102.6
81.5(4)
77.5(4)
dicular to the Cp plane. The zirconium–chloride bond
˚
distances in 6, 2.509(3) A, is slightly longer than in 5.
Other geometric parameters resemble previous examples
[5–12].
The last product isolated from the reaction of 1-Li with
CpZrCl3 was the bis(ferrocenyl phenoxyimine) zirconium
dichloride complex 3, crystallised as CH2Cl2 solvate. The
structure is shown in Fig. 5, with selected bond lengths
and angles collected in Table 5. The complex possesses
distorted octahedral goemetry. The phenoxy-oxygen
atoms occupy trans positions [\O(1)–Zr–O(2)
166.5(2)ꢁ], similar to Fujitaꢀs bis(N-phenyl phenoxyi-
mine) zirconium complex, ZrCl2(Ph–PI)2 [13]. This leaves
the nitrogen atoms in cis positions [\N(1)–Zr–N(2)
75.3(2)ꢁ] and trans to the chlorine ligands. The bond
lengths in 3 are very similar to Fujitaꢀs complex. The
Fig. 3. Molecular structure of CpZrCl2(FcPI)(THF) (5), showing the
atomic numbering scheme. Thermal ellipsoids at drawn 50%
probability.

R.K.J. Bott et al. / Polyhedron 25 (2006) 387–396
391
Fig. 5. Molecular structure of ZrCl2(FcPI)2 Æ CH2Cl2 (3 Æ CH2Cl2),
showing the atomic numbering scheme. Thermal ellipsoids are drawn
at 50% probability.
Fig. 4. Molecular structure of CpZrCl(FcPI)2 (6) showing the atomic
numbering scheme. Thermal ellipsoids at drawn at 50% probability.
Table 4
Table 5
˚
˚
Selected bond lengths (A) and angles (ꢁ) for (FcPI)2ZrCpCl (6)
Selected bond lengths (A) and angles (ꢁ) for (FcPI)2ZrCl2 Æ CH2Cl2
(3 Æ CH2Cl2)
Zr–N(1)
Zr–O(1)
Zr–N(2)
Zr–O(2)
Zr–Cl
2.434(8)
2.064(7)
2.375(9)
2.030(7)
2.509(3)
2.289
Zr–N(1)
Zr–O(1)
Zr–Cl(1)
Zr–N(2)
Zr–O(2)
Zr–Cl(2)
2.341(5)
1.988(4)
2.4394(14)
2.367(4)
1.984(4)
2.4202(16)
Zr–Cp
Fe(1)–Cp11
Fe(1)–Cp12
Fe(2)–Cp21
Fe(2)–Cp22
1.647
1.663
1.665
1.660
Fe(1)–Cp11
Fe(1)–Cp12
Fe(2)–Cp21
Fe(2)–Cp22
1.654
1.661
1.656
1.651
O(1)–Zr–N(1)
N(2)–Zr–N(1)
O(2)–Zr–N(1)
N(1)–Zr–Cl
Cp–Zr–N(1)
O(1)–Zr–N(2)
O(2)–Zr–O(1)
O(1)–Zr–Cl
Cp–Zr–O(1)
O(2)–Zr–N(2)
N(2)–Zr–Cl
Cp–Zr–N(2)
O(2)–Zr–Cl
Cp–Zr–O(2)
Cp–Zr–Cl
75.6(3)
74.2(3)
82.2(3)
80.6(2)
177.6
87.8(3)
156.1(2)
92.1(2)
103.8
77.7(3)
154.0(2)
103.5
92.96(19)
98.0
O(1)–Zr–N(1)
N(1)–Zr–N(2)
O(2)–Zr–N(1)
N(1)–Zr–Cl(1)
N(1)–Zr–Cl(2)
O(1)–Zr–N(2)
O(2)–Zr–O(1)
O(1)–Zr–Cl(1)
O(1)–Zr–Cl(2)
N(2)–Zr–Cl(1)
O(2)–Zr–Cl(1)
Cl(2)–Zr–Cl(1)
O(2)–Zr–N(2)
N(2)–Zr–Cl(2)
O(2)–Zr–Cl(2)
76.65(16)
75.29(16)
93.66(16)
90.52(13)
164.63(13)
91.75(17)
166.51(18)
96.59(12)
92.63(12)
161.45(11)
92.82(12)
101.77(6)
76.55(17)
94.35(11)
94.91(12)
101.8
Cp11–Fe(1)–Cp12
Cp21–Fe(2)–Cp22
177.6
177.4
Cp11–Fe(1)–Cp12
Cp21–Fe(2)–Cp22
177.0
177.6
˚
Zr–Cl distances in 3, 2.4394(14) and 2.420(2) A, are signif-
˚
icantly shorter than those found in 6 [2.509(3) A].
(electron transfer is slow relative to scan rate) one-elec-
tron transfers for the FeII–FeIII redox couple of the ferr-
ocenyl species are observed (Table 6). The dominant
species recorded in the CV for 1 has a DEp of 77 mV
(Fig. 6), a good correspondence to that for a reversible
reaction where n = 1 (for a fully reversible ‘‘Nernstian’’
2.3. Electrochemistry
Cyclic voltammetry (CV) of the ligand 1 and zirco-
nium complex 3 show that in each case quasi-reversible

392
R.K.J. Bott et al. / Polyhedron 25 (2006) 387–396
Table 6
mV) suggests n = 2, or the compound is adsorbed onto
the electrode (DEp = 0 mV).
Cyclic voltammetry of 1 and 3
Compound
Ecp ðmVÞ
446
505
455
Eap ðmVÞ
560
582
568
E1/2 (mV)
DEp
On coordination of the ligand to the zirconium metal
centre, the FeII/FeIII oxidation shifts to a lower poten-
tial, which is unexpected [8]. The two ferrocene moieties
show independent behaviour, resulting in identical
potentials. A shoulder appearing on the flank of the ma-
jor signal for 3, E1/2 = 644 mV, may be due to a redox
active oxidation product or an impurity. In a similar
cyclic voltammetry study over a wider potential range,
this shoulder became more prominent after irreversible
electrochemical oxidation took place, while the peaks
of the major species assigned to 3 were unchanged by
this process.
Ferrocene (Fc)
(FcPI)H (1)
(FcPI)2ZrCl2 (3)
503
543
511
104
77
113
i / A
0.600x10-5
0.500x10-5
0.400x10-5
0.300x10-5
0.200x10-5
0.100x10-5
0
-0.100x10-5
-0.200x10-5
-0.300x10-5
-0.250
2.4. Polymerisation studies
0
0.250
0.500
0.750
1.000
1.250
The ethylene polymerisation of two representative
examples of ferrocenyl-substituted phenoxyimine com-
plexes, 3 and 4, was investigated using MAO as the
activator.
E vs Ag/AgCl
Fig. 6. Cyclic voltammogram of 1 in dry dichloromethane with 0.1 M
in [nBu4N]+[PF6]ꢀ as supporting electrolyte.
Complex 4/MAO (Al:Ti = 4000) readily polymerises
ethene (1 bar) at room temperature with a productivity
of 1 · 104 g PE (molꢀ1 Ti) Æ hꢀ1 Æ barꢀ1 (Table 7)
(PE = polyethylene). This activity is quite similar to that
exhibited by the mesityl-substituted analogue, CpTiCl2
(MesPI) (1.3 · 104 g PE (molꢀ1 Ti) Æ hꢀ1 Æ barꢀ1) [10b].
By contrast, the bis(ferrocene phenoxyimine)zirco-
nium dichloride, 3, when activated with MAO, shows
very high activity at 23 ꢁC, 2 · 106 g PE (molꢀ1
Zr) Æ hꢀ1 Æ barꢀ1, which increased further on cooling to
0 ꢁC and on reducing the catalyst concentration. This
activity is less than that reported by Fujita for
(PhPI)2ZrCl2/MAO, although those results were ob-
tained with a substantially higher Al/Zr ratio of
62500:1. The catalyst based on 3 is thermally unstable,
however, and conducting the polymerisation at 60 ꢁC
afforded only traces of polymer; again this is in line with
the known behaviour of phenoxyimine catalysts which
are prone to deactivation by C@N double bond reduc-
tion [10d,13–15]. Interestingly, complex 3 differs from
the titanium complex 4 as well as comparable alkyl
and aryl-substituted zirconium catalysts in producing
ethene oligomers with excellent productivities, with
average degrees of polymerisation of 12–16.
i / A
0.125x10-4
0.100x10-4
0.075x10-4
0.050x10-4
0.025x10-4
0
-0.025x10-4
-0.050x10-4
0
-0.250
0.250
0.500
0.750
1.000
1.250
E vs Ag/AgCl
Fig. 7. Cyclic voltammogram of 3 (CH2Cl2, 0.1 M [nBu4N]+[PF6]ꢀ).
type redox couple, DEp = 60 mV for n = 1). For 3, the
major species couple has DEp = 113 mV (Fig. 7);
although a lot larger than 60 mV, it is in line with the
DEp of ferrocene (104 mV, n = 1). The difference is
probably due to different electron transfer kinetics.
The CV for 1 also shows a minor signal, E1/2 = 134–
503 mV = ꢀ369 mV, similar to one reported by Gibson
et al. [8]. These authors assigned this signal to an irre-
versible electrochemical reduction of C@N to an amine
group, although in the case of 1 this process appears to
be reversible. DEp = 44 mV for this signal (E1/2 = 116
Table 7
Ethylene polymerisation data
Complex (lmol)
T (ꢁC) Time (min) MAO (mmol) Toluene (mL) Activity (g molꢀ1 hꢀ1 barꢀ1
)
Mw
Mw/Mn Ref.
13 this work
9.3
4 (5)
4 (5)
23
60
15
15
15
5
2
2
50
50
1.6 · 104
2.1 · 104
1.3 · 104
0.4 · 107
0.2 · 107
2.6 · 107
5.5 · 108
350000
164000
328000
640
600
750
this work
[10b]
CpTiCl2(MesPI) (40) 25
8
50
1.5
1.7
1.7
1.7
2.06
3 (10)
3 (10)
3 (1)
0
23
23
25
10
10
10
50
50
50
250
this work
this work
this work
[13]
5
1
5
2 I (0.02)
1.25
90000 (Mv)

R.K.J. Bott et al. / Polyhedron 25 (2006) 387–396
393
3. Experimental
NMR (C6D6) d 169.8 (C@N), 142.1 (ar-C), 134.6 (ar-
C), 132.5 (ar-C), 122.0 (ar-C), 114.5 (ar-C), 105.8 (ar-
C), 70.0 (Cp), 67.8 (N–Cp), 66.9 (THF), 62.9 (N–Cp),
35.6 (N–Cp), 35.6 (C(CH3)3), 29.9 (C(CH3)3), 25.7
(THF). Anal. Calc. for C42H44N2O2Fe2Mg.OC4H8: C,
61.98; H, 6.24; N, 2.89. Found: C, 61.62; H, 7.29; N,
2.90%.
Unless otherwise stated, syntheses were performed
with exclusion of oxygen and moisture under nitrogen
using standard Schlenk techniques in flame-dried glass-
ware. Solvents were distilled over sodium benzophenone
(diethyl ether, tetrahydrofuran), sodium (toluene), so-
dium–potassium alloy (petroleum ether, bp 40–60 ꢁC),
or CaH2 (dichloromethane). NMR solvents were dried
3.3. Preparation of (FcPI)2ZrCl2 (3)
˚
over activated 4 A molecular sieves and degassed by sev-
eral freeze–thaw cycles. NMR spectra were recorded
using a Bruker DPX300 spectrometer. Chemical shifts
are reported in ppm and referenced to residual solvent
resonances (1H, 13C), 19F is relative to CFCl3. Nitrogen,
argon and ethene (BOC, 99.5%) were purified by passing
through columns of supported P2O5 with moisture indi-
cator, and activated 4 A molecular sieves. Aminoferro-
cene was prepared according to the literature
procedures [16].
Sodium hydride (0.07 g, 3.0 mmol) was added to a
solution of 1-H (1.00 g, 2.8 mmol) in tetrahydrofuran
(50 mL). The dark red solution was stirred for 3 h at
room temperature, cooled to ꢀ78 ꢁC. Zirconium tetra-
chloride was added (0.32 g, 1.4 mmol), the mixture
was allowed to reach room temperature and stirred for
18 h. The volatiles were removed in vacuo, and the
resulting dark red solid was extracted with dichloro-
methane (50 mL), concentrated and layered with light
petroleum. The title compound was obtained as dark
red micro-crystals (0.51 g, 0.6 mmol, 42%) at ꢀ20 ꢁC.
This sample recovered did not contain dichloromethane
of crystallisation. 1H NMR (CCl2D2): d 9.10 (s, 1H,
CH@N), 7.50 (d, 1H, J = 6.2 Hz, ar-H), 7.19 (d, 1H,
J = 6.3 Hz, ar-H), 6.87 (d, 1H, J = 7.1 Hz, ar-H), 4.49
(br, 1H, Cp–H), 4.17 (br, 5H, Cp–H), 3.84 (br, 1H,
˚
3.1. Preparation of 2-tert-butyl-6-
(N-ferrocenylaldimino)phenol, (FcPI)H (1-H)
3-tert-Butylsalicylaldehyde (2.1 g, 12 mmol) was
added dropwise to a stirred mixture of aminoferrocene
˚
(2.3 g, 11.4 mmol) with molecular sieves 4 A (2 g) in eth-
t
anol (50 mL), at room temperature. The mixture was
stirred for 18 h, filtered and the molecular sieves washed
with diethyl ether (20 mL). Crystallisation from the con-
centrated solution gave 1-H as a red microcrystalline
Cp–H), 3.68 (br, 1H, Cp–H), 1.46 (s, 9H, Bu). 13C
NMR (CCl2D2): d 172.9 (CH@N), 159.7 (ar-C), 134.4
(ar-C), 133.3 (ar-C), 123.9 (ar-C), 120.0 (ar-C), 69.7
(FcCH, C5H5), 66.9 (FcCH, C5H4), 64.9 (FcCH,
C5H4), 35.2 (C(CH3)3), 29.9 (C(CH3)3). Anal. Calc. for
C42H44N2O2Cl2Fe2Zr: C, 57.15;H, 5.02; N, 3.17; Cl,
8.03. Found: C, 56.82; H,5.28; N, 3.05; Cl, 9.42.
1
powder (2.7 g, 7.5 mmol, 65%). H NMR (300 MHz,
298 K, CDCl3): d 8.61 (s, 1H, CH@N), 7.34 (d, 1H,
J = 7.8 Hz, ar-H), 7.14 (d, 1H, J = 7.8 Hz, ar-H), 6.82
(t, 1H, J = 7.8 Hz, ar-H), 4.57 (m, 2H, C5H4N), 4.25
t
(m, 2H, C5H4N), 4.17 (s, 5H, C5H5), 1.45 (s, 9H, Bu).
3.4. Preparation of CpTiCl2(FcPI) Æ CH2Cl2 (4)
13C NMR (75.5 MHz, 298 K, CDCl3): d 161.1 (CH@N),
137.5 (ar-C), 129.5 (ar-CH), 129.3 (ar-CH), 119.5 (ar-C),
118.2 (ar-CH), 102.4 (ar-C), 69.8 (C5H5), 67.4 (C5H4N),
62.4 (C5H4N), 34.9 (C(CH3)3), 29.4 (C(CH3)3). Anal.
Calc. for C21H23NOFe: C, 69.82; H, 6.42; N, 3.88.
Found: C, 69.72; H, 6.56; N, 3.85%.
The lithium salt 1-Li, prepared from 1-H (0.5 g, 1.38
mmol) and nBuLi (0.9 mL, 1.6 M in hexanes, 1.38
mmol), was treated with CpTiCl3 (0.30 g, 1.38 mmol)
in THF (50 mL), stirred at ꢀ78 ꢁC for 20 min, allowed
to reach room temperature and stirred overnight. The
volatiles were removed under vacuum and the product
extracted with CH2Cl2 (20 mL). The solution was con-
centrated, layered with light petroleum and cooled to
ꢀ20 ꢁC to give 4 as dark red/brown, cubic crystals
3.2. Preparation of (FcPI)2Mg(THF)2 (2)
Dibutylmagnesium (1.0 M in hexanes, 1 mL, 1 mmol)
was added dropwise to a stirred solution of 1-H (0.72 g,
2 mmol) in THF at ꢀ78 ꢁC. The mixture was allowed to
reach room temperature and stirred for 15 h. The solu-
tion was then concentrated, carefully layered with light
petroleum and cooled to 5 ꢁC to afford the title com-
pound as red crystals in 51% yield (0.45 g, 0.5 mmol).
1H NMR (C6D6): d 8.63 (s, 1H, CH@N), 7.54 (dd,
1H, J = 7.4, 1.7 Hz, ar-H), 7.09 (dd, 1H, J = 7.8, 1.5
Hz, ar-H), 6.70 (t, 1H, J = 7.6 Hz, ar-H), 4.30 (m, 2H,
N–Cp), 3.89 (s, 5H, Cp), 3.73 (m, 2H, N–Cp), 3.56 (m,
1
(0.28 g, 0.4 mmol, 32%). H NMR (C6D6): d 9.54 (s,
1H, CH@N), 8.35 (d, 1H, J = 7.4 Hz, ar-H), 7.43 (d,
1H, J = 7.5 Hz, ar-H), 6.80 (t, 1H, J = 7.6 Hz, ar-H),
6.31 (s, 5H, Cp), 4.28 (m, 4H, NC5H4), 3.95 (m, 5H,
t
Cp), 1.56 (s, 9H, Bu). 13C NMR (C6D6) d 129.8 (ar-
C), 128.3 (ar-C), 124.3 (ar-C), 124.0 (ar-C), 122.1 (ar-
C), 121.9 (Cp), 70.1 (FeC5H4), 69.9 (FeC5H4), 53.3
(FeC5H5), 35.2 (C(CH3)3), 29.7 (C(CH3)3). Anal. Calc.
for C26H27NOCl2TiFe Æ CH2Cl2: C, 51.55; H, 4.65; N,
2.23; Cl, 22.54. Found: C, 51.70; H, 4.63; N, 2.07; Cl,
21.78%.
t
8H, THF), 1.70 (s, 9H, Bu), 1.40 (m, 8H, THF). 13C

Table 8
Crystal data and collection parameters for complexes 2–6
(FcPI)2Mg(THF)2 (2)
CpTiCl2(FcPI) Æ CH2Cl2 (4 Æ CH2Cl2) CpZrCl2(FcPI)(THF) (5) CpZrCl(FcPI)2 (6)
(FcPI)2ZrCl2 Æ CH2Cl2 (3 Æ CH2Cl2)
Empirical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
C
889.01
0.30 · 0.25 · 0.10
hexagonal
50H60Fe2MgN2O4
C26H27Cl2FeNOTi Æ CH2Cl2
629.1
C30H35Cl2FeNO2Zr
659.56
0.25 · 0.05 · 0.05
monoclinic
P21/c (No. 14)
140(1)
17.236(3)
9.527(2)
18.743(4)
90
113.04(3)
90
C47H49ClFe2N2O2Zr
912.25
0.40 · 0.15 · 0.02
monoclinic
C2/c (No. 15)
140(1)
32.212(6)
17.876(4)
17.339(4)
90
116.76(3)
90
C42H44Cl2Fe2N2O2Zr Æ CH2Cl2
967.54
0.65 · 0.20 · 0.10
orthorhombic
P212121 (No. 19)
140(1)
7.797(1)
13.525(1)
25.894(1)
90
90
90
2730.6(4)
4
1.237
0.35 · 0.30 · 0.15
orthorhombic
Pna21 (No. 33)
140(1)
16.547(3)
16.543(3)
15.227(3)
90
ꢀ
P3c1 ðNo: 165Þ
T (K)
140(1)
19.043(3)
19.043(3)
22.970(5)
90
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
120
7214(2)
6
0.659
90
90
3
˚
V (A )
2832.2(10)
4
1.097
8915(3)
8
0.969
3760
4168.2(14)
4
1.227
Z
l (mmꢀ1
F(000)
)
2820
1288
1352
1976
Reflections collected
5848
13422
6888
11033
7216
Independent reflections (Rint
Number of ꢁunobservedꢀ reflections 1863
)
3141 (0.040)
4556 (0.036)
4430
3673 (0.097)
2123
5822 (0.110)
2666
7216
5711
Final R indices
R indices (all data)
Goodness-of-fit
R1 = 0.084, wR2 = 0.258 R1 = 0.028, wR2 = 0.070
R1 = 0.123, wR2 = 0.279 R1 = 0.029, wR2 = 0.071
R1 = 0.127, wR2 = 0.346 R1 = 0.060, wR2 = 0.164 R1 = 0.045, wR2 = 0.112
R1 = 0.176, wR2 = 0.369 R1 = 0.138, wR2 = 0.187 R1 = 0.060, wR2 = 0.119
1.045
1.075
1.115
0.895
0.991

R.K.J. Bott et al. / Polyhedron 25 (2006) 387–396
395
3.5. Isolation of (FcPI)2ZrCl2 Æ CH2Cl2 (3),
CpZrCl2(FcPI) (5) and CpZrCl(FcPI)2 (6)
applied in SORTAV [19]. The structures were determined
by direct methods in the SHELXS programs and refined
by full-matrix least-squares methods, on F2 values, in
SHELXL [20]. Crystal and refinement data are given in
Table 8. Hydrogen atoms were included in idealized
positions, and their Uiso values set to ride on the Ueq
values of the parent carbon atoms. Scattering factors
for neutral atoms were taken from the literature [21].
Computer programs were run on a DEC-AlphaStation
200 4/100 in the Biological Chemistry Department, John
Innes Centre.
Following the procedure given for 4, to a solution of
1-Li (1.38 mmol) in THF (50 mL) was added
CpZrCl3 Æ DME (0.49 g, 1.38 mmol). The volatiles were
removed and the products extracted with CH2Cl2. The
solution was concentrated and layered with light petro-
leum. Dark red-brown cubic crystals of (FcPI)2ZrCl2 Æ
CH2Cl2 (3 Æ CH2Cl2) dark red-brown needle clusters of
CpZrCl(FcPI)2 (6) and red-brown cubic crystals of
CpZrCl2(FcPI)(THF) (5), which were isolated from the
same Schlenk flask and picked out manually. The com-
pounds were identified by X-ray crystallography. Unlike
the preparation of 3 from 1-Na, this crystallisation pro-
duced the dichloromethane solvate, 3 Æ CH2Cl2. No fur-
ther characterisation has been undertaken.
4. Supplementary material
Full tables of bond lengths and angles, tables of non-
hydrogen and hydrogen atomic coordinates and aniso-
tropic thermal parameters for non-hydrogen atoms are
available from the Cambridge Crystallographic Data
Centre, quoting CCDC deposition numbers 269489
(compound 2), 269490 (4), 269491 (3), 269492 (6) and
269493 (5). Copies of the information may be obtained
free of charge from The Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336
033; e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
3.6. Ethylene polymerisations
Ethylene polymerisation was carried out under 1 bar
ethene in toluene. Toluene (total volume 50 mL includ-
ing MAO) and co-catalyst (MAO) were introduced into
the ethylene-purged reactor and stirred. After ethylene
saturation and temperature equilibration, polymerisa-
tion was initiated by addition of a toluene solution of
pre-catalyst into the reactor under vigorous stirring
(1000 rpm). After the required amount of time, metha-
nol (5 mL) was added to terminate the polymerisation,
and the ethene gas flow halted. The polymer was precip-
itated, washed with a mixture of methanol (ꢁ300 mL)
and 15% HCl (ꢁ5 mL), filtered, washed with methanol
and dried in an oven at 80 ꢁC to constant mass.
Acknowledgements
This work was supported by the Engineering and
Physical Sciences Research Council and the European
Commission (Contract HPRN-CT-2000-00004). We
thank Dr. J.N. Butt (UEA) for assistance with electro-
chemical measurements.
3.7. Electrochemistry
Electrochemical data were obtained at 298 K using a
glassy-carbon working electrode, a platinum-wire auxil-
iary electrode and a silver wire (coated with AgCl by
anodising in KCl solution) pseudo-reference electrode.
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