Titanium imido complexes of pendant arm functionalised benzamidinate ligands

Article abstract of DOI:10.1039/b207184c

Reactions of the lithiated pendant arm functionalised benzamidinates Li{Me₂NCH₂CH₂NC(Ph)NSiMe₃} and Li{Me₂NCH₂CH₂CH₂NC(Ph)NSiMe ₃} with the compounds [Ti(NR

Full text of DOI:10.1039/b207184c

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Titanium imido complexes of pendant arm functionalised
benzamidinate ligands
Catherine L. Boyd, Aldo E. Guiducci, Stuart R. Dubberley, Ben R. Tyrrell and
Philip Mountford*
Inorganic Chemistry Laboratory, South Parks Road, Oxford, UK OX1 3QR
Received 23rd July 2002, Accepted 23rd August 2002
First published as an Advance Article on the web 17th October 2002
Reactions of the lithiated pendant arm functionalised benzamidinates Li{Me2NCH2CH2NC(Ph)NSiMe3} and
Li{Me2NCH2CH2CH2NC(Ph)NSiMe3} with the compounds [Ti(NR)Cl2(py)3] (R = tBu, 2,6-Me2C6H3, 2,6-iPr2C6H3)
afforded five-coordinate [Ti(NR){Me2NCH2CH2NC(Ph)NSiMe3}Cl] 1–3 and [Ti(NR){Me2NCH2CH2CH2NC-
(Ph)NSiMe3}Cl] 4–6, respectively. Reaction of [Ti(NtBu){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] 4 with C6F5NH2
gave elimination of tBuNH2 and the corresponding perfluoroarylimido complex 7. The X-ray crystal structures of
[Ti(NtBu){Me2NCH2CH2NC(Ph)NSiMe3}Cl] 1 and [Ti(N-2,6-R2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl]
(R = Me 5 or iPr 6) have been determined. Reaction of either 1 or 4 with H2N-2,6-Me2C6H3 in C6D6 afforded the
corresponding arylimido compounds 2 and 5, but this route is not amenable to easy scale-up. For better evaluation
of the effects of the pendant NMe2 donor group in 1–6, the bis(pyridine) compound [Ti(NtBu){MeCH2CH2NC-
(Ph)NSiMe3}Cl(py)2] 9 was prepared from Li{MeCH2CH2NC(Ph)NSiMe3} 8 and [Ti(NtBu)Cl2(py)3]. The
compounds 1–3 with two-carbon pendant arms are quite sensitive to adventitious protonation, and the X-ray
crystal structures of the products of two such reactions, namely [Ti {Me NCH CH N᎐C(Ph)N(H)SiMe } (NtBu) Cl -
᎐
2
2
2
2
3
2
2
2
(µ-Cl) ] 10 and [Ti (N-2,6-C H Me ) Cl (µ-O){Me NCH CH N᎐C(Ph)N(H)SiMe } ] 11, have been determined. Both
᎐
2
2
6
3
2
2
2
2
2
2
3 2
possess amidine ligands that show interesting intramolecular N–H ؒ ؒ ؒ X (X = µ-Cl or µ-O) hydrogen bonds.
dependent equilibria with five-coordinate II, whilst III is
Introduction
dinuclear with bridging imido ligands. Accessible from I/II via
chloride ligand metathesis reactions are alkyl, cyclopentadienyl,
amide, aryloxide and borohydride derivatives,6 and so the
amidinate–imide combination is a useful supporting ligand set.
Furthermore, on revisiting recently some cyclopentadienyl–
amidinate supported imido systems and their homologues we
found that the complexes [Ti(NR)(η-C5Me5){MeC(NiPr)2}]
(Ar = substituted phenyl groups) react with CO2 (via an initial
cycloaddition reaction) to form [Ti(η-C5Me5){MeC(NiPr)2}-
{O(CO)N(Ar)(CO)O}]; the double CO2 activation reaction
leading to these compounds was the first example for any
transition metal imide.7
Transition metal imido complexes continue to provide a rich
seam of reactivity, both at the M᎐NR bond itself and with the
᎐
imido group acting as a supporting ligand.1,2a,b We have been
interested in developing the chemistry of titanium imido com-
pounds2 in both of these regards. As part of these studies we
previously prepared a series of amidinate-supported com-
plexes3,4 starting from the appropriate chloride derivatives
t
[Ti(NR){PhC(NSiMe3)2}Cl(py)2] (I, R = Bu or aryl) or [Ti2-
(µ-NBut)2{MeC(NC6H11)2}2Cl2] III as presented in Chart 1.5 As
shown, compounds I exist in temperature- and R group-
We have therefore been interested to open up further the
chemistry of amidinate-supported imido compounds. A well-
established strategy that we have recently employed in titanium
imido chemistry with considerable success2b is the use of hemi-
labile ligands, specifically those having pendant donor groups
that can stabilise an otherwise reactive Ti᎐NR moiety, poten-
᎐
tially decoordinate during a reaction sequence, and stabilise as
required any Ti᎐NR coupling product so-formed. With this in
᎐
mind we noted with interest recent reports by Hessen and
Teuben and coworkers8 and Lappert et al.9 of the pendant arm
functionalised benzamidinate ligands Me2NCH2CH2NC(Ph)-
NSiMe3 and Me2NCH2CH2CH2NC(Ph)NSiMe3. The lithiated
derivatives (dimeric for the three-carbon arm system and pre-
sumably also dimeric for the other, two-carbon homologue) of
these ligands are readily available in good yields. Complexes of
lithium (dinuclear), aluminium, gallium, cerium (dinuclear with
chloride bridges), yttrium (and a dinuclear yttrium–lithium
“ate” complex) and vanadium have so far been reported and
crystallographically characterised. The Me2N(CH2)nNC(Ph)-
NSiMe3 (n = 2 or 3) ligands have shown both mer- and
fac-tridentate coordination modes, as well as bidentate
ones with the pendant NMe2 nitrogen non-coordinated; The
dinuclear compounds with bridging amidinate ligands have had
Chart 1
DOI: 10.1039/b207184c
J. Chem. Soc., Dalton Trans., 2002, 4175–4184
This journal is © The Royal Society of Chemistry 2002
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the PhC(NSiMe3)N moiety bound to one metal (yttrium in the
case of the mixed metal dinuclear Y–Li complex) and the NMe2
donor bound to the second metal centre.
(1)
Given the lack of any Group 410 or metal–ligand multiply-
bonded derivatives of these ligands, and of the potential use of
such hemi-labile amidinate ligands in titanium imido chemistry
in general, we set out to prepare titanium imido complexes of
both Me2N(CH2)nNC(Ph)NSiMe3 (n = 2 or 3) ligands, and this
is the subject of our present contribution.11
In several previous studies2,12 we have found that arylimido
compounds [Ti(NAr)(Ln)] (Ln is a supporting ligand or ligand
set) can be prepared from the tert-butylimido homologues
[Ti(NtBu)(Ln)] by reaction of the latter with the appropriate
aniline, ArNH2. An NMR tube scale reaction between [Ti-
(NtBu){Me2NCH2CH2NC(Ph)NSiMe3}Cl]1andH2N-2,6-Me2-
C6H3 in C6D6 showed quantitative formation of 2 and the
expected tert-butylamine side-product. However, attempts to
scale this reaction up were always hampered by problems of
separation of the product 2 from residual amines (presumably
because of weak coordination to the remaining vacant site in
five-coordinate 2).
Results and discussion
Syntheses
In our previous work in titanium imido chemistry we have
found that chloride and/or pyridine substitution reactions of
t
the compounds [Ti(NR)Cl2(py)3] (R = Bu or aryl)12 is a very
reliable route to new imido complexes. The reactions between
t
[Ti(NR)Cl2(py)3] (R = Bu, 2,6-Me2C6H3 or 2,6-iPr2C6H3) and
the lithiated ligands Li{Me2NCH2CH2NC(Ph)NSiMe3}8 and
Li{Me2NCH2CH2CH2NC(Ph)NSiMe3}9 (prepared as reported
previously by Hessen and Teuben, and Lappert) are summar-
ised in Scheme 1.
The H and 13C NMR spectra for the new compounds 1–3
support the proposed structures and confirm that the
CH2CH2NMe2 arm is coordinated to the metal centre. In all of
these compounds, each of the four diastereotopic methylene
1
1
hydrogens gives rise to an individual H NMR multiplet, and
the two methyl groups appear as inequivalent sharp singlets in
1
the H and 13C spectra. The imido N-substituents give rise to
the expected resonances. The methyl groups of the aryl ring
iso-propyl substituents in 3 are inequivalent as required by the
absence of a molecular mirror plane in this compound.
The corresponding reactions (Scheme 1) of [Ti(NR)Cl2(py)3]
with the lithiated three-carbon pendant arm ligand similarly
affordedfive-coordinatecomplexes,namely[Ti(NR){Me2NCH2-
CH2CH2NC(Ph)NSiMe3}Cl] (R = tBu 4, 2,6-Me2C6H3 5 or 2,6-
iPr2C6H3 6) in 67, 31 and 69% yields, respectively. The physical
and spectroscopic properties of these new compounds are
analogous to those of 1–3. The NMR spectra suggest firm
coordination of the NMe2 moiety to titanium, with sharp
resonances arising from each of the six inequivalent arm
methylene protons and the two inequivalent NMe2 methyl
groups (as confirmed by the X-ray structures of 5 and 6 dis-
cussed in a later section). Full assignment of these resonances
1
1
was possible from 2-dimensional H–1H, H–13C and ROESY
NMR spectra; one reason for carrying this out this being the
observation of a low-field shifted resonance (δ ca. 2.9 ppm) for
one of the hydrogens of the methylene linkage next to the NMe2
group in 5 and 6 (but not in 4 or the two-carbon arm complexes
1–3); the other H atom of this methylene group appears at
δ ca. 1.6 ppm in 5 and 6. The unusual shift is unambiguously
assigned to the axial H atom (i.e. oriented “up”, more or less
parallel to the Ti᎐NAr bond) which apparently feels some
᎐
anisotropic deshielding effects from the arylimido groups in 5
and 6.
Scheme 1
t
The compounds [Ti(NR)Cl2(py)3] (R = Bu or aryl) react
with Li{Me2NCH2CH2NC(Ph)NSiMe3} smoothly in benzene
at room temperature to form [Ti(NR){Me2NCH2CH2NC(Ph)-
(2)
t
NSiMe3}Cl] (R = Bu 1, 2,6-Me2C6H3 2 or 2,6-iPr2C6H3 3) as
benzene-soluble, air- and moisture-sensitive compounds in
69–85% yield. These are the first metal–ligand multiply-bonded
ligand complexes of any pendant arm functionalised amidinate
ligand. The tert-butylimido compound 1 can be recrystallised
from cold pentane yielding diffraction-quality crystals from
which the X-ray structure of 1 has been determined (see below)
and which supports the structures proposed for 1–3. The
arylimido analogues 2 and 3 do not easily crystallise, but can be
sublimed at high vacuum in low yields (<20%) to yield analytic-
ally pure samples. However, the initial products of reaction,
after extraction to separate 1–3 from the LiCl side-product, are
sufficiently pure to use in further reactions.
As with [Ti(NtBu){Me2NCH2CH2NC(Ph)NSiMe3}Cl] 1, the
three-carbon arm system 4 undergoes quantitative and facile
tert-butylimide/aniline exchange with H2N-2,6-Me2C6H3 on an
NMR tube scale in C6D6 to form 5 (eqn. (2)). Again it is more
convenient on scale-up to prepare 5 directly from the dichloride
[Ti(N-2,6-Me2C6H3)Cl2(py)3] and Li{Me2NCH2CH2CH2NC-
(Ph)NSiMe3}.
4176
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Table 1 Selected bond distances (Å) and angles (Њ) for [Ti(NtBu)-
{Me2NCH2CH2NC(Ph)NSiMe3}Cl] 1
We were also interested to prepare perfluoroarylimido ana-
logues of 4–6 to compare their reactivity and determine their
X-ray structures (we have very recently found that perfluoro-
arylimido complexes can feature interesting π-stacked supra-
molecular solid state structures).2e Unfortunately we have so
far been unable to prepare in suitably pure form the required
synthon [Ti(NC6F5)Cl2(py)3], and so reaction of this with
Li{Me2NCH2CH2CH2NC(Ph)NSiMe3} (as for 4–6) was not a
possibile route. The target complex [Ti(NC6F5){Me2NCH2-
CH2CH2NC(Ph)NSiMe3}Cl] 7 therefore had to be prepared by
the tert-butylimide/perfluoroaniline exchange method summar-
ised in eqn. (2). The reaction proceeds in a very good crude
yield of over 90%. But while >90% spectroscopically pure,
samples of 7 were always contaminated with residual amine.
Pure samples were obtained in less than 5% yield by high
vacuum tube sublimation and, disappointingly, it has not been
possible to obtain diffraction-quality crystals of 7. The 1H
NMR spectrum of 7, like those of 5 and 6, showed very differ-
ent chemical shifts (δ 2.99 and 1.71 ppm) for the two hydrogen
atoms of the methylene group adjacent to NMe2.
Ti(1)–N(1)
Ti(1)–N(2)
Ti(1)–N(3)
Ti(1)–N(4)
1.688(2)
2.126(2)
2.095(2)
2.248(2)
Ti(1)–Cl(1)
N(2)–Si(1)
N(2)–C(5)
N(3)–C(5)
2.3231(6)
1.735(2)
1.339(3)
1.325(3)
Ti(1)–N(1)–C(1)
N(1)–Ti(1)–N(2)
N(1)–Ti(1)–N(3)
N(2)–Ti(1)–N(3)
Ti(1)–N(2)–C(5)
Si(1)–N(2)–C(5)
Ti(1)–N(3)–C(12)
175.0(2)
116.07(8)
107.85(8)
63.14(6)
88.7(1)
132.3(1)
123.8(1)
N(1)–Ti(1)–Cl(1)
N(1)–Ti(1)–N(4)
N(3)–Ti(1)–N(4)
N(2)–C(5)–N(3)
Ti(1)–N(2)–Si(1)
Ti(1)–N(3)–C(5)
C(5)–N(3)–C(12)
109.42(6)
106.08(8)
73.89(6)
112.1(2)
138.62(9)
90.4(1)
125.7(2)
pyridine ligands thus lying in a meridional coordination mode,
the remaining MeCH2CH2NC(Ph)NSiMe3 and chloride ligands
must adopt the relative coordination sites shown for 9 in
eqn. (3), with both N donors of the benzamidinate ligand being
cis to the imido ligand. The structure of 9 is in contrast to the
six-coordinate complexes [Ti(NR){PhC(NSiMe3)2}Cl(py)2] I
in which the two chemically equivalent pyridine ligands are
mutually trans (and cis to the imido group), with one of the benz-
amidinate nitrogens being cis to NR and one approximately
trans, presumably to minimise the number of NtBu/NSiMe3
cis-interactions. Finally we note that 9 is not particularly stable
in solution. Solutions of 9 in C6D6 in sealed tubes under N2
show significant signs of degradation to unknown product(s)
after one or two hours at ambient temperature, and this
thwarted attempts to obtain an analytically pure sample. This
instability provides further evidence for the importance of
the pendant arm coordination in the comparatively stable
complexes 1–7.
(3)
As mentioned above and summarised in Chart 1, the
benzamidinate-supported imidotitanium complexes [Ti(NR)-
{PhC(NSiMe3)2}Cl(py)2] (I, R = Bu or aryl) exist in dynamic
X-Ray structures of 1, 5 and 6
The X-ray crystal structure of [Ti(NtBu){Me2NCH2CH2-
NC(Ph)NSiMe3}Cl] 1 is shown in Fig. 1 and selected bond dis-
tances and angles are given in Table 1. Molecules of 1 have a
square base pyramidal geometry. The atoms N(2), N(3), N(4)
and Cl(1) form the square base with Ti(1) lying 0.75 Å out of
the least squares best-fit plane containing these atoms. The
N(1)–Ti(1)–Lbase angles are in excess of 105Њ which is a feature
of metal–ligand multiply-bonded compounds of this kind.13
t
equilibrium with the 5-coordinate, mono-pyridine complexes
II. The compounds 1–7 clearly do not bind pyridine (present in
the reaction mixtures) tightly, an observation that can be attrib-
uted to features of the Me2N(CH2)nNC(Ph)NSiMe3 (n = 2 or 3)
pendant arms, coupled with the trans-labilising effect of the
imido ligands themselves. To make a better comparison of the
complexes 1–7 with the non-pendant arm species I/II we pre-
pared (eqn. (3)) a sterically comparable benzamidinate com-
pound [Ti(NtBu){MeCH2CH2NC(Ph)NSiMe3}Cl(py)2] 9 by
reaction of [Ti(NtBu)Cl2(py)3] with Li{MeCH2CH2NC(Ph)-
NSiMe3}ؒ(Et2O) 8.† The ligand MeCH2CH2NC(Ph)NSiMe3 in
9 is in all regards comparable to the NMe2-functionalised ones,
apart from obviously not having the additional pendant donor
group.
The Ti᎐N
and Ti–Cl distances are at the short end of the
᎐
imide
range of values found for imidotitanium compounds,14 but con-
sistent with the 14 valence electron count. The Me2NCH2CH2-
The structure proposed for 9 (eqn. (3)) is fully consistent with
the NMR data. Thus, in addition to expected resonances for the
1
NtBu and MeCH2CH2NC(Ph)NSiMe3 ligands, the H NMR
spectrum shows two very different pyridine ligand environ-
ments. The ortho hydrogen resonances for these two chemically
1
distinct ligands appear at δ 9.55 and ca. 8.7 ppm. All the H
resonances for the pyridine associated with the more downfield
ortho resonance are sharp, whereas those for the other pyridine
are rather broad. ROESY NMR spectra of 9 established that
the two pyridines are in dynamic exchange on the NMR time-
scale, and a weak nOe between the SiMe3 group of CH3CH2-
CH2NC(Ph)NSiMe3 and the sharp ortho hydrogen at δ 9.55
ppm suggested that these two groups are probably mutually
cis to each other. The chemical shifts of the broad pyridine
resonances suggest that this ligand lies opposite the very
trans-labilising tert-butylimido group. With the NtBu and two
† Note added at proof: molecules of 8 possess a dinuclear structure
in the solid state. C. L. Boyd, B. R. Tyrrell and P. Mountford,
Acta Crystallogr., Sect. E, 2002, 58, m597.
Fig.
1
Molecular structure of [Ti(NtBu){Me2NCH2CH2NC(Ph)-
NSiMe3}Cl] 1. Displacement ellipsoids are drawn at the 25%
probability level. H atoms omitted for clarity.
J. Chem. Soc., Dalton Trans., 2002, 4175–4184
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Table 2 Selected bond distances (Å) and angles (Њ) for [Ti(N-2,6-
Me2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] 5 and [Ti(N-2,6-
iPr2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] 6
5
6
Ti(1)–N(1)
Ti(1)–N(2)
Ti(1)–N(3)
Ti(1)–N(4)
Ti(1)–Cl(1)
N(2)–Si(1)
N(2)–CPh
N(3)–CPh
1.713(1)
2.124(1)
2.080(1)
2.223(1)
2.3234(4)
1.734(1)
1.337(2)
1.316(2)
1.713(3)
2.110(2)
2.085(2)
2.228(3)
2.3386(9)
1.735(3)
1.340(4)
1.317(4)
Ti(1)–N(1)–C(1)
N(1)–Ti(1)–N(2)
N(1)–Ti(1)–N(3)
N(1)–Ti(1)–N(4)
N(2)–Ti(1)–N(3)
N(3)–Ti(1)–N(4)
N(1)–Ti(1)–Cl(1)
Ti(1)–N(2)–CPh
Ti(1)–N(2)–Si(1)
Si(1)–N(2)–CPh
Ti(1)–N(3)–CPh
Ti(1)–N(3)–CH2
PhC–N(3)–CH2
178.58(9)
104.53(4)
110.09(5)
98.13(4)
63.71(4)
83.16(14)
113.67(4)
89.77(7)
129.04(6)
131.58(8)
92.26(7)
138.75(8)
125.4(1)
175.0(2)
109.03(12)
107.30(11)
102.19(11)
63.51(9)
82.7(1)
111.32(9)
91.2(2)
133.83(13)
134.5(2)
92.9(2)
139.9(2)
126.9(2)
NC(Ph)NSiMe3 ligand adopts a κ3-coordination geometry with
the pendant arm firmly coordinated as indicated above by
1
the solution H and 13C NMR data. Interestingly the benz-
amidinate nitrogen donors feature different degrees of
planarity, with N(3) being distinctly pyramidalised. This is
apparent from visual inspection of the molecular structure, but
is also quantified by the sums of the angles subtended at N(2)
(359.5(3)Њ, i.e. planar within error) and at N(3) (339.9(4)Њ). The
pyramidalisation of N(3) can be attributed to distortions
required to achieve coordination of the pendant NMe2 group.
Despite the pyramidalisation of N(3) the Ti(1)–N(2) distance is
significantly longer than Ti(1)–N(3) (difference = 0.031(3) Å).
Factors contributing to this observation could be unfavour-
able steric interactions arising from the SiMe3 group, and the
additional binding through N(4) which would favour closer
coordination of N(3). There is a small and marginally signifi-
cant difference between the N(2)–C(5) (longer) and N(3)–C(5)
bond lengths (difference = 0.014(4) Å).
Fig. 2 Molecular structures of (a) [Ti(N-2,6-Me2C6H3){Me2NCH2-
CH2CH2NC(Ph)NSiMe3}Cl] 5 (25% probability ellipsoids) and (b)
[Ti(N-2,6-iPr2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl]
probability) with H atoms omitted for clarity.
6 (20%
It was important to be able to compare solid state structures
of complexes of the three-carbon pendant arm ligand
Me2NCH2CH2CH2NC(Ph)NSiMe3 with that of 1. We were not
able to grow diffraction-quality crystals of the tert-butylimido
longer that those for N(3)–CPh (differences 0.021(3) and
0.023(6) Å for 5 and 6, respectively). These small but persistent
differences may be attributable (directly or indirectly) to steric
factors associated with the SiMe3 group.
system [Ti(NtBu){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl]
4
(or indeed of 2 or 3) which would have allowed the best com-
parison. However, we have been able to determine the X-ray
structures of the two arylimido compounds [Ti(N-2,6-R2C6H3)-
Products of trace hydrolysis in the two-carbon pendant arm
systems
i
{Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] (R = Me 5 or Pr 6).
Perhaps unsurprisingly in the light of the somewhat strained
structure discussed for 1, all three compounds [Ti(NR){Me2-
NCH2CH2NC(Ph)NSiMe3}Cl] 1–3 are significantly more
sensitive to adventitious protonation-hydrolysis than their
three-carbon arm homologues. We include here two X-ray
structures of these hydrolysis compounds since they (i)
show interesting molecular features; (ii) demonstrate potential
drawbacks of pendant arm amidinates with arms that are
too short; (iii) suggest possible uses of the parent amidine
The molecular structures are shown in Fig. 2 and selected bond
distances and angles are summarised and compared in Table 2.
The structures of 5 and 6 are broadly analogous to that of 1.
The Ti᎐N
distances are somewhat longer in the arylimido
᎐
imide
systems as is usually the case.12,13 The titanium atoms in 5 and 6
lie 0.64 and 0.67 Å out of the least-squares plane of the
{N(2),N(3),N(4),Cl(1)} donor set (corresponding value in 1 is
0.75 Å) suggesting that the three-carbon atom arm ligand
allows for a more comfortable accommodation of the Ti᎐NR
ligands Me NCH CH N᎐C(Ph)N(H)SiMe in supramolecular
᎐
2 2 2 3
᎐
moiety. The N(3) atoms in 5 and 6 are effectively planar with
the sums of the angles subtended at these atoms being 356.5(4)
and 359.7(6)Њ, respectively. The longer chain pendant arm leads
to increased N(4)–Ti(1)–N(3) angles of 83.16(14) and 82.7(1)Њ
in 5 and 6 compared to a more acute angle of 73.89(6)Њ in 1. As
in compound 1 the Ti(1)–N(2) distances in 5 and 6 are signifi-
cantly longer than the Ti(1)–N(3) distances, presumably for the
same reasons. As also in 1, the N(2)–CPh distances are slightly
chemistry.
Fig. 3 shows the molecular structure of [Ti2{Me2NCH2-
CH N᎐C(Ph)N(H)SiMe } (NtBu) Cl (µ-Cl) ] 10; selected bond
᎐
2
3
2
2
2
2
lengths and angles are listed in Table 3. Compound 10 is
dinuclear with bridging chloride ligands and crystallographic-
ally imposed Ci symmetry. It is evidently the product of
formally inserting HCl (presumably from hydrolysis of a
Ti–Cl bond of 1) into the Me3SiN–Ti bond of [Ti(NtBu)-
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Table 3 Selected bond distances (Å) and angles (Њ) for [Ti2{Me2-
The Me NCH CH N᎐C(Ph)N(H)SiMe amidine ligand in
᎐
2
2
2
3
NCH2CH2N᎐C(Ph)N(H)SiMe3}2(NtBu)2Cl2(µ-Cl)2] 10
᎐
10 could potentially be interesting in supramolecular type
applications, it being simultaneously a dual Lewis base donor
(through the amidine imino and pendant arm amino nitrogens)
and a hydrogen bond donor through the Me3SiN–H group. In
10 this group forms an intramolecular N(4)–H(1) ؒ ؒ ؒ Cl(2)
hydrogen bond, the refined H(1) ؒ ؒ ؒ Cl(2) distance of 2.75(2)
being in the acceptable range for such interactions.2e,16 However,
it is not clear if the hydrogen bonds in 10 have an important role
in setting the structural features of this compound or are simply
opportunistic consequences of the coordination geometry. The
role of an analogous hydrogen bond in the binculear complex
Ti(1)–N(1)
Ti(1)–N(2)
Ti(1)–N(3)
Ti(1)–Cl(1)
Ti(1)–Cl(2)
Ti(1)–Cl(2B)
1.694(1)
2.318(1)
2.192(1)
2.3685(4)
2.4223(5)
2.8539(5)
N(3)–C(9)
N(4)–C(9)
N(4)–H(1)
N(4)–Si(1)
Cl(2) ؒ ؒ ؒ H(1)
1.307(2)
1.349(2)
0.80(2)
1.771(2)
2.75(2)
Ti(1)–N(1)–C(1)
N(1)–Ti(1)–N(2)
N(1)–Ti(1)–N(3)
Cl(1)–Ti(1)–N(1)
Cl(2)–Ti(1)–N(1)
169.8(1)
98.44(6)
97.46(6)
99.11(5)
97.61(5)
Ti(1)–Cl(2)–Ti(1B)
Cl(1)–Ti(1)–Cl(2B)
N(4)–H(1) ؒ ؒ ؒ Cl(2) 127(2)
C(9)–N(4)–Si(1)
C(9)–N(4)–H(1)
H(1)–N(4)–Si(1)
103.630(15)
85.556(15)
132.7(1)
112(2)
112(2)
[Ti (N-2,6-C H Me ) Cl (µ-O){Me NCH CH N᎐C(Ph)N(H)-
᎐
2
6
3
2
2
2
2
2
2
Cl(2B)–Ti(1)–N(1) 172.81(5)
SiMe3}2] 11 (see below) is much less ambiguous. Hughes, Wade
et al. have recently reported a mononuclear complex of a non-
pendant arm amidine ligand that shows a close intramolecular
hydrogen bond, the hydrogen bond donor being the amino
nitrogen of the amidine ligand.17
Attempted crystallisation of [Ti(N-2,6-Me2C6H3){Me2-
NCH2CH2NC(Ph)NSiMe3}Cl] 2 gave a small number of
crystals of [Ti (N-2,6-C H Me ) Cl (µ-O){Me NCH CH N᎐
᎐
2
6
3
2
2
2
2
2
2
C(Ph)N(H)SiMe3}2] 11. The molecular structure is shown in
Fig. 4, and selected bond lengths and angles are listed in Table
Fig.
3
Molecular structure of [Ti2{Me2NCH2CH2N᎐C(Ph)N(H)-
᎐
SiMe3}2(NtBu)2Cl2(µ-Cl)2] 10. Displacement ellipsoids are drawn at the
25% probability level. H atoms bound to C are omitted and H(1) is
drawn as a sphere of arbitrary radius. Atoms carrying the suffix ‘B’ are
related to their counterparts by the symmetry operator [Ϫx, Ϫy, 1 Ϫ z].
Fig. 4 Molecular structure of [Ti2(N-2,6-C6H3Me2)2Cl2(µ-O){Me2-
NCH2CH2N᎐C(Ph)N(H)SiMe3}2] 11. Displacement ellipsoids are
᎐
drawn at the 30% probability level. H atoms bound to C are omitted
and H(1) is draw as a sphere of arbitrary radius. Atoms carrying the
suffix ‘B’ are related to their counterparts by the symmetry operator
[½ Ϫ x, Ϫy, 3/2 Ϫ z].
{Me2NCH2CH2NC(Ph)NSiMe3}Cl] 1, and indeed can be pre-
pared, albeit in impure form, by the addition of NH2Me2Cl
(a source of HCl) to 1. Compound 10 contains the “parent”
amidine ligand Me NCH CH N᎐C(Ph)N(H)SiMe . While a
4. The solution 1H NMR spectrum of 11 is consistent with the
solid state structure. In particular a broad resonance at δ 10.6
ppm (integral 2 H per dimeric molecule) is assigned to the
N–H ؒ ؒ ؒ O hydrogen atoms. Molecules of 11 (which lie on
crystallographic two-fold axes) apparently form from reaction
of adventitious H2O with two molecules of 2, with the O–H
bonds formally inserting into the Ti–NSiMe3 bonds of 2. Again
᎐
2
2
2
3
large number of non-pendant arm amidine complexes have
been reported3,14 only one crystallographically characterised
pendant arm amidine derivative has been previously described,
this being the cation [Co{H NCH CH N᎐C(NH )CH NH }-
᎐
2
2
2
2
2
2
(tmeda)Cl]ϩ.15 The N(3)–C(9) distance of 1.307(2) Å in 10 is
significantly shorter than the N(4)–C(9) value of 1.349(2) Å,
suggesting that N(3) is best considered as an imino nitrogen and
N(4) as an amino nitrogen. The Lewis base coordination of the
the neutral Me NCH CH N᎐C(Ph)NSiMe amidine ligand
᎐
2
2
2
3
shows shorter N(3)–C(13) [1.308(3) Å] than N(4)–C(13)
[1.352(3) Å] distances, consistent with N(3) being an imino
nitrogen and N(4) an amino nitrogen. Like 10, the amidine
ligand acts as a Lewis base through the pendant NMe2 and
imino nitrogens, and a hydrogen bond donor through the
Me3SiN–H group, this time to a bridging oxo ligand. The
geometry at O(1) is close to tetrahedral and the N–H ؒ ؒ ؒ O
distances and angles are consistent with the formation of strong
intramolecular hydrogen bonds.14 Very interestingly, the Ti(1)–
O(1)–Ti(1B) angle has the highly acute value of 113.7(1)Њ. Over
60 bridging mono-oxo complexes [(Ln)Ti(µ-O)Ti(Ln)] have been
crystallographically characterised and the mean Ti–O–Ti angle
amidine moiety of the Me NCH CH N᎐C(Ph)N(H)SiMe
᎐
2
2
2
3
ligand through the imino rather than amino nitrogen is highly
typical of amidine ligands.14 In 10 coordination through N(3) is
particularly favoured by further coordination through the
dimethylamino nitrogen N(2). The possibility of coordination
through N(2) might also contribute to the explanation of why it
is N(4) that ends up with the added proton rather than the
presumably more basic (and distorted in the X-ray structure of
1) N(3) atom. Indeed N(3) might well be the kinetic site of
electrophilic attack by Hϩ on 1 but we have no evidence either
way for this hypothesis.
J. Chem. Soc., Dalton Trans., 2002, 4175–4184
4179

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Table 4 Selected bond distances (Å) and angles (Њ) for [Ti2(N-2,6-C6H3Me2)2Cl2(µ-O){Me2NCH2CH2N᎐C(Ph)N(H)SiMe3}2] 11
᎐
Ti(1)–N(1)
Ti(1)–N(2)
Ti(1)–N(3)
Ti(1)–Cl(1)
Ti(1)–O(1)
1.729(2)
2.307(2)
2.198(2)
2.4103(6)
1.8808(11)
N(3)–C(13)
N(4)–C(13)
N(4)–H(1)
N(4)–Si(1)
O(1) ؒ ؒ ؒ H(1)
1.308(3)
1.352(3)
0.88(3)
1.767(2)
2.02(3)
Ti(1)–N(1)–C(1)
N(1)–Ti(1)–N(2)
N(1)–Ti(1)–N(3)
Cl(1)–Ti(1)–N(1)
O(1)–Ti(1)–N(1)
Ti(1)–O(1)–Ti(1)B
N(4)–H(1) ؒ ؒ ؒ O(1)
174.4(2)
96.62(7)
101.45(7)
104.44(6)
106.21(7)
113.7(1)
161(3)
Ti(1)–O(1) ؒ ؒ ؒ H(1)
Ti(1)–O(1)–H(1B)
H(1) ؒ ؒ ؒ O(1) ؒ ؒ ؒ H(1B)
C(13)–N(4)–H(1)
Si(1)–N(4)–H(1)
96(1)
116(1)
121(2)
113(2)
116(2)
131.64(14)
C(13)–N(4)–Si(1)
is 171(7)Њ (range ca. 152–180Њ).14 This preference for linearity
[Ti(NtBu){Me2NCH2CH2NC(Ph)NSiMe3}Cl] (1)
stems from a requirement to minimise steric interactions
To a stirred solution of [Ti(NtBu)Cl2(py)3] (1.01 g, 2.35 mmol)
in benzene (40 ml) was added a solution of Li{Me2NCH2CH2-
NC(Ph)NSiMe3} (0.63 g, 2.35 mmol) in benzene (20 ml) drop-
wise over 15 min. The orange solution became orange–yellow in
colour and a white precipitate formed. Volatiles were removed
under reduced pressure and extracted into benzene (50 ml). The
waxy orange residue was recrystallised at Ϫ80 ЊC from pentane
(20 ml), yielding [Ti(NtBu){Me2NCH2CH2NC(Ph)NSiMe3}Cl]
as an orange–yellow powder with some single diffraction-
quality crystals. Yield: 0.68 g (69%).
between the two titanium centres and to maximise O2π Ti3dπ
π
interactions. It seems very likely that the two strong N–H ؒ ؒ ؒ O
interactions cause the highy bent Ti–O–Ti linkage in 11.
Conclusions
We have prepared in good yield the first transition metal imido
complexes of pendant arm functionalised amidinate ligands.
Three of these complexes have been structurally characterised.
The pendant arm allows the isolation of well-defined five-
coordinate amidinate–imido complexes of a type not previously
possible with non-pendant arm amidinates. It is likely that these
compounds will form the starting point for further explor-
ing titanium imido chemistry. Two products arising from
protonation–hydrolysis have been structurally characterised,
and the µ-oxo compound 11 in particular shows an unusual
geometry attributed to the hydrogen bond donor ability of the
1H NMR data (CD2Cl2, 500.0 MHz, 293 K): δ 7.5–7.3 (5 H,
m, C6H5), 3.75 (1 H, m, CN2CH2), 3.31 (1 H, m, Me2NCH2),
3.03 (3 H, s, NMe2), 3.01 (1 H, m, CN2CH2), 2.36 (1 H, m,
Me2NCH2), 2.16 (3 H, s, NMe2), 1.02 (9 H, s, CMe3), 0.90 (9 H,
s, SiMe3). 13C-{1H} NMR data (CD2Cl2, 125.7 MHz, 289 K):
δ 173.74 (CN2), 134.25 (ipso-C6H5), 130.41, 128.50, 127.86,
123.8, 123.60 (5 CH of C6H5), 70.31 (CMe3), 62.71 (Me2-
NCH2), 50.18 (NMe2), 46.12 (CN2CH2), 46.12 (NMe2),
32.10 (CMe3), 1.48 (SiMe3). IR data (KBr plates, Nujol mull,
cmϪ1): 2727 (w), 1603 (w), 1578 (w), 1505 (w), 1349 (m),
1329 (w), 1245 (m), 1204 (m), 1176 (w), 1153 (w), 1134 (w),
1087 (w), 1073 (w), 1046 (w), 1023 (w), 950 (w), 933 (w), 869
(m), 836 (m), 793 (w), 776 (w), 757 (w), 723 (w), 702 (w),
627 (w), 594 (w), 563 (w), 515 (w), 500 (w), 442 (w) cmϪ1. Anal.
found (calc. for C18H33ClN4SiTi): C 51.7 (51.9), H 7.5 (8.0), N
13.4 (13.4)%.
parent amidine ligand Me NCH CH N᎐C(Ph)NSiMe .
᎐
2
2
2
3
Experimental
General methods and instrumentation
The compounds Li{Me2NCH2CH2NC(Ph)NSiMe3},8 Li{Me2-
NCH2CH2CH2NC(Ph)NSiMe3}9 and [Ti(NR)Cl2(py)3] (R =
tBu, 2,6-Me2C6H3, 2,6-iPr2C6H3)12 were prepared as reported
previously.
[Ti(N-2,6-Me2C6H3){Me2NCH2CH2NC(Ph)NSiMe3}Cl] (2)
General methods and instrumentation
To a stirred solution of [Ti(N-2,6-Me2C6H3)Cl2(py)3] (0.54 g,
1.14 mmol) in benzene (30 ml) was added a solution of
Li{Me2NCH2CH2NC(Ph)NSiMe3} (0.31 g, 1.14 mmol) in
benzene (15 ml) dropwise over 10 min. The solution remained
brown in colour and a white precipitate formed. Volatiles were
removed under reduced pressure and extracted into benzene
(30 ml). The residue was triturated with pentane (20 ml)
giving 2 as a brown solid. Yield: 0.38 g (72%). An analytic-
ally pure sample was obtained by sublimation at 1 × 10Ϫ6 mbar
and 160 ЊC to yield [Ti(N-2,6-Me2C6H3){Me2NCH2CH2-
NC(Ph)NSiMe3}Cl] as a red–brown oil which hardened to a
red–brown solid upon standing at rt. Sublimed yield: 59 mg
(16%).
All manipulations were carried out using standard Schlenk line
or drybox techniques under an atmosphere of argon or of
dinitrogen. Solvents were predried over activated 4 Å molecular
sieves and were refluxed over appropriate drying agents under a
dinitrogen atmosphere and collected by distillation. Deuterated
solvents were dried over appropriate drying agents, distilled
under reduced pressure, and stored under dinitrogen in Teflon
valve ampoules. NMR samples were prepared under dinitrogen
in 5 mm Wilmad 507-PP tubes fitted with J. Young Teflon
valves. 1H, 13C{1H}, 13C and 19F NMR spectra were recorded on
1
Varian Unity Plus 500 and Varian Mercury spectrometers. H
and 13C assignments were confirmed when necessary with the
use of NOE, DEPT-135, DEPT-90, DEPT-45, and two dimen-
An attempt to crystallise [Ti(N-2,6-Me2C6H3){Me2NCH2-
CH2NC(Ph)NSiMe3}Cl] 2 yielded a small quantity of crystals
1
sional H–1H and 13C–1H NMR experiments. All spectra were
referenced internally to residual protio-solvent (1H) or solvent
(13C) resonances and are reported relative to tetramethylsilane
(δ = 0 ppm). Chemical shifts are quoted in δ (ppm) and coupling
constants in hertz (Hz). Infrared spectra were prepared as
Nujol mulls between NaCl or KBr plates or as KBr discs and
were recorded on Perkin-Elmer 1600 and 1700 series spectro-
meters. Infrared data are quoted in wavenumbers (cmϪ1). Mass
spectra were recorded by the mass spectrometry service of the
University of Oxford’s Inorganic Chemistry Laboratory. Com-
bustion analyses were recorded by the analytical services of the
University of Oxford’s Inorganic Chemistry Laboratory.
of
[Ti (N-2,6-C H Me ) Cl (µ-O){Me NCH CH N᎐C(Ph)-
᎐
2 6 3 2 2 2 2 2 2
N(H)SiMe3}2] (11). Data for [Ti(N-2,6-Me2C6H3){Me2NCH2-
CH2NC(Ph)NSiMe3}Cl] (2). 1H NMR (C6D6, 500.0 MHz, 293
K): δ 7.17 (2 H, d of d, ortho-C6H5, 2J = 7.8, 3J = 1.5), 6.98–7.03
(5 H, m, meta- and para-C6H5 and meta-C6H3Me2), 6.73 (1 H, t,
2
para-C6H3Me2, J = 7.3), 3.10 (1 H, m, CN2CH2), 2.86 (6 H, s,
C6H3Me2), 2.63 (1 H, m, CN2CH2), 2.43 (3 H, s, NMe), 2.27
(1 H, m, CH2NMe2), 2.00 (3 H, s, NMe), 1.63 (1 H, m,
CH2NMe2), 0.18 (9 H, s, SiMe3). 13C{1H} NMR (C6D6,
75.5 MHz, 293 K): δ 174.43 (CN2), 160.30 (ipso-C6H3Me2),
134.67 (ipso-C6H5), 132.59 (ortho-C6H3Me2), 130.53 (meta- or
4180
J. Chem. Soc., Dalton Trans., 2002, 4175–4184

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para-C6H5 or meta-C6H3Me2), 128.65 (meta- or para-C6H5 or
meta-C6H3Me2), 127.87 (ortho-C6H5), 127.38 (meta- or para-
C6H5 or meta-C6H3Me2), 120.68 (para-C6H3Me2), 62.92 (CH2-
NMe2), 49.45 (NMe), 47.78 (NMe), 45.97 (CN2CH2), 20.17
(C6H3Me2), 2.22 (SiMe3). IR (Nujol mull, KBr plates): 1892 (w,
br), 1828 (w), 1770 (w), 1606 (w), 1582 (m), 1504 (w), 1404 (s),
1342 (m), 1312 (s), 1250 (m), 1198 (m), 1172 (w), 1158 (w),
1088 (m), 1076 (m), 1062 (w), 1050 (w), 1024 (w), 984 (w), 966
(w), 946 (m), 930 (w), 864 (s), 842 (s), 808 (w), 792 (w), 778 (w),
758 (m), 738 (m), 722 (w), 628 (w), 616 (w, br), 582 (w), 562 (w),
498 (w), 476 (w), 444 (w), 422 (w) cmϪ1. Accurate mass EI-MS
for [Ti(N-2,6-Me2C6H3){Me2NCH2CH2NC(Ph)NSiMe3}Cl]ϩ.
Found (calc. for C22H33N4ClSiTi): m/z = 464.1630 (464.1643).
Anal. found (calc. for C22H33N4ClSiTi): C 56.6 (56.8), H 7.3
(7.2), N 12.2 (12.1)%.
[Ti(NtBu){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] (4)
To a stirred solution of [Ti(NtBu)Cl2(py)3] (0.98 g, 2.30 mmol)
in benzene (60 ml) was added a solution of Li{Me2NCH2CH2-
CH2NC(Ph)NSiMe3} (0.65 g, 2.30 mmol) in benzene (20 ml),
dropwise over 10 min. The resulting orange–yellow solution
was stirred for 3 days. Volatiles were removed under reduced
pressure and extracted into benzene (40 ml). The product was
triturated with pentane (20 ml). Upon standing at rt a waxy
orange solid formed. Yield: 0.66 g (67%).
1H NMR data (C6D6, 500.0 MHz, 293 K): δ 7.4–7.0 (5 H, m,
C6H5), 3.10 (2 H, m, CN2CH2), 2.83 (3 H, s, NMe2), 2.04 (1 H,
m, Me2NCH2(ax)), 1.87 (3 H, s, NMe2), 1.82 (1 H, m, Me2-
NCH2(eq)), 1.38 (1 H, m, CH2CH2CH2(ax)), 1.23 (9 H, s, CMe3),
0.95 (1 H, m, CH2CH2CH2(eq)), 0.28 (9 H, s, SiMe3). 13C-{1H}
NMR data (C6D6, 125.7 MHz, 293 K): 174.60 (CN2), 136.04
(ipso-C6H5), 129.00, 128.6, 128.19, 127.80, 126.63 (5 CH of
C6H5), 70.77 (CMe3), 62.95 (Me2NCH2), 52.35 (NMe2), 47.49
(CN2CH2), 43.94 (NMe2), 32.65 (CMe3), 25.84 (CH2CH2CH2),
2.42 (SiMe3). IR data (KBr plates, Nujol mull, cmϪ1): 2724 (w),
1593 (w, br), 1466 (s, br), 1347 (m), 1302 (m), 1262 (w), 1244
(m), 1205 (s), 1154 (m), 1131 (w), 1109 (w), 1062 (w), 1016 (m),
978 (W), 946 (m), 923 (w), 897 (m), 857 (w), 841 (m), 818 (m),
786 (m), 764 (w), 721 (w), 707 (w), 629 (w), 597 (w), 547 (m),
510 (w), 455 (w), 435 (w) cmϪ1. Anal. found (calc. for
C19H53ClN4SiTi): C 53.0 (53.0), H 7.8 (8.2), N 12.8 (13.0)%.
Data for [Ti(N-2,6-C H Me )Cl(µ-O){Me NCH CH N᎐
᎐
6
3
2
2
2
2
C(Ph)N(H)SiMe3}]2 (11). 1H NMR (C6D6, 500.0 MHz, 293 K):
δ 10.61 (2 H, s, NH), 7.48–7.57 (6 H, m, meta- and para-C6H5),
2
7.40 (2 H, d, ortho-C6H5, J = 7.3), 7.27 (2 H, d, ortho-C6H5,
2J = 7.3), 6.69 (4 H, d, meta-C6H3Me2), 6.33 (2 H, t, para-
C6H3Me2), 3.51, 3.41, 3.20 (3 × 2 H, m, CH of pendant arm),
2.88 (6 H, s, C6H3Me2), 2.61 (6 H, s, C6H3Me2), 2.33–2.54 (14 H,
overlapping br s and m, NMe2 and CH of pendant arm), 0.04
(18H, s, SiMe3).
NMR tube scale reaction of [Ti(NtBu){Me2NCH2CH2NC(Ph)-
NSiMe3}Cl] (1) with 2,6-dimethylaniline
[Ti(N-2,6-Me2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl]
(5)
A solution of 1 (6.8 mg, 0.016 mmol) in C6D6 (0.5 ml) in a 5 mm
NMR tube was treated with ca. 1.0 equiv. of 2,6-dimethyl-
1
To a stirred solution of [Ti(N-2,6-Me2C6H3)Cl2(py)3] (0.56 g,
1.18 mmol) in benzene (40 ml) was added a solution of
Li{Me2NCH2CH2CH2NC(Ph)NSiMe3} (0.33 g, 1.18 mmol) in
benzene (20 ml) dropwise over 10 min. The brown solution
became red–brown in colour and a white precipitate formed.
Volatiles were removed under reduced pressure and extracted
into benzene (30 ml). The brown oily residue was recrystallised
at rt from CH2Cl2 (5 ml) and hexane (30 ml), yielding 5 as
red–brown diffraction-quality crystals. Yield: 0.18 g (31%).
1H NMR (C6D6, 500.0 MHz, 293 K): δ 7.26–7.20 (2 H, d, br,
aniline at rt. The H NMR spectrum after 10 min showed
quantitative formation of 2 together with a new resonance
attributable to tBuNH2.
[Ti(N-2,6-iPr2C6H3){Me2NCH2CH2NC(Ph)NSiMe3}Cl] (3)
To a stirred solution of [Ti(N-2,6-iPr2C6H3)Cl2(py)3] (0.68 g,
1.29 mmol) in benzene (30 ml) was added a solution of
Li{Me2NCH2CH2NC(Ph)NSiMe3} (0.35 g, 1.29 mmol) in ben-
zene (15 ml) dropwise over 10 min. The solution remained
brown in colour and a white precipitate formed. Volatiles were
removed under reduced pressure and extracted into benzene
(20 ml). The residue was triturated with pentane (30 ml) giving
3 as a brown solid. Yield: 0.51 g (85%). An analytically pure
sample was obtained by sublimation at 7 × 10Ϫ6 mbar and
100 ЊC to yield [Ti(N-2,6-iPr2C6H3){Me2NCH2CH2NC(Ph)-
NSiMe3}Cl] as a brown oil which hardened to a brown solid on
standing at rt. Sublimed yield: 63 mg (19%).
2
ortho-C6H5, J = 4.9), 7.10–7.02 (3 H, m, br, meta- and para-
2
C6H5), 6.99 (2 H, app d, meta-C6H3Me2, app J = 7.3), 6.71
2
(1 H, t, para-C6H3Me2, J = 7.8), 3.02 (1 H, m, CN2CH2ax),
2.95 (1 H, m, CN2CH2eq), 2.87 (1 H, app t, Me2NCH2ax, app
2J = 12.7), 2.82 (6 H, s, C6H3Me2), 2.59 (3 H, s, NMe2eq), 1.90 (3
2
3
H, s, NMe2ax), 1.62 (1 H, d of d, Me2NCH2eq, J = 12.7, J =
5.4), 1.21 (1 H, m, CH2CH2CH2ax), 0.87 (1 H, br d, CH2CH2-
2
CH2eq, J = 15.6), 0.12 (9 H, s, SiMe3). 13C{1H} NMR (C6D6,
1H NMR (C6D6, 500.0 MHz, 293 K): δ 7.19–7.22 (2 H, m, br,
75.5 MHz, 293 K): δ 174.95 (CN2), 160.30 (ipso-C6H3Me2),
134.97 (ipso-C6H5), 132.58 (ortho-C6H3Me2), 129.24 (meta-
or para-C6H5), 128.47 (meta- or para-C6H5), 127.70 (meta-
C6H3Me2), 127.28 (ortho-C6H5), 120.65 (para-C6H3Me2), 62.18
(CH2NMe2), 52.70 (NMeeq), 45.90 (CN2CH2), 45.87 (NMeax),
25.50 (CH2CH2CH2), 20.16 (C6H3Me2), 2.20 (SiMe3). IR
(Nujol mull, KBr plates): 2360 (w), 2338 (w), 1946 (w), 1894
(w), 1876 (w), 1830 (w), 1650 (w), 1604 (w), 1582 (w), 1506 (m),
1444 (s, br), 1412 (s, br), 1342 (s), 1316 (s), 1244 (s), 1204 (m),
1228 (m), 1176 (w), 1154 (w), 1128 (w), 1104 (m), 1058 (m),
1026 (w), 1008 (m), 978 (m), 946 (w), 916 (w), 892 (s), 838 (s),
818 (s), 780 (m), 734 (m), 698 (m), 628 (w), 554 (w), 514 (m), 494
(w), 436 (w), 412 (m) cmϪ1. Accurate mass EI-MS for [Ti(N-2,6-
i
2
ortho-C6H5), 7.09 (2 H, app d, meta-C6H3 Pr2, app J = 7.3),
7.00–7.05 (3 H, m, br, meta- and para-C6H5), 6.90 (1 H, t, para-
i
2
2
C6H3 Pr2, J = 7.3), 4.71 (2 H, septet, CHMe2, J = 6.8), 3.16
(1 H, m, CN2CH2), 2.60 (1 H, m, CN2CH2), 2.49 (3 H, s, NMe),
2.37 (1 H, m, CH2NMe2), 1.97 (3 H, s, NMe), 1.61 (1 H, m,
2
CH2NMe2), 1.54 (6 H, d, CHMe2, J = 6.8), 1.49 (6 H, d,
CHMe2, J = 6.8), 0.19 (9 H, s, SiMe3). 13C{1H} NMR (C6D6,
2
i
75.5 MHz, 293 K): δ 176.36 (CN2), 157.73 (ipso-C6H3 Pr2),
143.18 (ipso-C6H5), 134.78 (ortho-C6H3 Pr2), 130.55 (meta- or
i
para-C6H5), 128.72 (meta- or para-C6H5), 127.85 (ortho-C6H5),
i
i
122.25 (meta-C6H3 Pr2), 121.58 (para-C6H3 Pr2), 62.92 (CH2-
NMe2), 49.32 (NMe), 47.68 (NMe), 45.99 (CN2CH2), 28.62
(CHMe2), 25.01 (CHMe2), 24.54 (CHMe2), 2.24 (SiMe3).
IR (Nujol mull, NaCl plates): 1916 (w), 1582 (w), 1504 (m),
1328 (s), 1378 (s), 1290 (s), 1250 (s), 1200 (s), 1174 (w), 1158 (w),
1140 (w), 1088 (m), 1048 (m), 1022 (m), 982 (m), 948 (s, br),
848 (s), 790 (s), 758 (s), 704 (m), 692 (m), 632 (w), 562 (m),
408 (s, br) cmϪ1. Accurate mass EI-MS for [Ti(N-2,6-
iPr2C6H3){Me2NCH2CH2NC(Ph)NSiMe3}Cl]ϩ. Found (calc.
for C26H41N4ClSiTi): m/z = 520.2105 (520.2083). Anal. found
(calc. for C26H41N4ClSiTi): C 59.6 (59.9), H 7.7 (7.9), N 11.0
(10.8)%.
Me2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl]ϩ.
(calc. for C23H35N4ClSiTi): m/z = 478.1816 (478.1799). Anal.
found (calc. for C23H35N4ClSiTi): C 57.6 (57.7), H 7.4 (7.4), N
11.5 (11.7)%.
Found
NMR tube scale reaction of [Ti(NtBu){Me2NCH2CH2CH2NC-
(Ph)NSiMe3}Cl] (4) with 2,6-dimethylaniline
A solution of 4 (7.0 mg, 0.016 mmol) in C6D6 (0.5 ml) in a 5 mm
NMR tube was treated with ca. 1.0 equiv. of 2,6-dimethyl-
J. Chem. Soc., Dalton Trans., 2002, 4175–4184
4181

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1
aniline at rt. The H NMR spectrum after 10 min showed
1198 (w), 1178 (w), 1158 (w), 1098 (w), 1042 (m), 1010 (s), 982
(s), 946 (m), 888 (m), 840 (s), 785 (m), 746 (m), 700 (s), 660 (m),
632 (w). Accurate mass EI-MS for [Ti(N-C6F5)-
{Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl]: found (calculated for
C21H26N4ClF5SiTi): 540.0989 (540.1015).
quantitative formation of 5 together with a new resonance
attributable to tBuNH2.
[Ti(N-2,6-iPr2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] (6)
To a stirred solution of [Ti(N-2,6-iPr2C6H3)Cl2(py)3] (0.63 g,
1.18 mmol) in benzene (30 ml) was added a solution of
Li{Me2NCH2CH2CH2NC(Ph)NSiMe3} (0.34 g, 1.18 mmol) in
benzene (30 ml) dropwise over 10 min. The solution remained
brown in colour and a white precipitate formed. Volatiles were
removed under reduced pressure and extracted into benzene
(30 ml). The brown oily residue was recrystallised at Ϫ30 ЊC
from hexanes (40 ml), yielding [Ti(N-2,6-iPr2C6H3){Me2NCH2-
CH2CH2NC(Ph)NSiMe3}Cl] as a beige power. Yield: 0.44 g
(69%). Diffraction-quality crystals of 6 were obtained by
diffusion of a solution of 6 in hexanes into paraffin oil.
Li{CH3CH2CH2NC(Ph)NSiMe3}ؒEt2O (8)
To a solution of propylamine (8.63 g, 0.15 mol) in Et2O (100
ml) at Ϫ78 ЊC was added 1.6 M nBuLi/hexanes solution (91 ml,
0.15 mol) over 30 min. A white precipitate formed and the mix-
ture was stirred for 16 h at rt. The reaction mixture was cooled
to Ϫ78 ЊC, trimethylsilylchloride (19 ml, 0.146 mol) added and
the mixture stirred for a further 16 h at rt. The mixture was
filtered and the white precipitate washed with 3 × 20 ml Et2O.
The combined filtrates were cooled to Ϫ78 ЊC and 1.6 M nBuLi/
hexanes solution (91 ml, 0.15 mol) was added over 30 min. The
mixture was stirred at rt for 16 h. Volatiles were removed under
reduced pressure yielding Li{CH3CH2CH2NSiMe3} as a pale
yellow oil. A protion of Li{CH3CH2CH2NSiMe3} (8.04 g, 59
mmol) was dissolved in Et2O (70 ml) and cooled to Ϫ78 ЊC.
Benzonitrile (6.04 g, 59 mmol) was added over 15 min. The
resulting orange solution was stirred at rt for 16 h. Volatiles
were removed under reduced pressure and the orange residue
extracted into hexane (40 ml). The mixture was filtered and the
white precipitate washed with hexane (3 × 15 ml). The filtrates
were combined and the volatiles removed under reduced pres-
sure to give a yellow oil. This was recrystallised from a mixture
of Et2O (10 ml) and pentane (30 ml) at Ϫ80 ЊC yielding 8 as a
pale yellow powder. Yield: 2.90 g (7%).
1H NMR (C6D6, 500.0 MHz, 293 K): δ 7.20–7.32 (2 H, m, br,
ortho-C6H5), 7.10–7.03 (3 H, m, br, meta- and para-C6H5), 7.05
i
2
(2 H, app d, meta-C6H3 Pr2, app J = 7.8), 6.88 (1 H, t, para-
i
2
2
C6H3 Pr2, J = 7.8), 4.80 (2 H, septet, CHMe2, J = 6.8), 2.99–
3.18 (3 H, m, CN2CH2ax, CN2CH2eq, CH2NMe2ax), 2.65 (3 H, s,
NMeeq), 1.90 (3 H, s, NMeax), 1.67 (1 H, d of d, CH2NMe2eq
,
2J = 12.7, 3J = 4.9), 1.48 (12 H, app t, CHMe2, app 2J = 6.8), 1.19
(1 H, m, CH2CH2CH2ax), 0.88 (1 H, m, CH2CH2CH2eq), 0.15
(9 H, s, SiMe3). 13C{1H} NMR (C6D6, 75.5 MHz, 293 K):
i
δ 175.17 (CN2), 157.57 (ipso-C6H3 Pr2), 143.48 (ipso-C6H5),
i
135.05 (ortho-C6H3 Pr2), 129.47 (meta- or para-C6H5 or meta-
i
i
C6H3 Pr2), 128.18 (meta- or para-C6H5 or meta-C6H3 Pr2),
127.85 (ortho-C6H5), 122.34 (meta- or para-C6H5 or meta-
i
i
C6H3 Pr2), 121.87 (para-C6H3 Pr2), 62.17 (CH2NMe2), 52.86
(NMeeq), 46.24 (NMeax), 45.86 (CN2CH2), 28.12 (CHMe2),
25.70 (CH2CH2CH2), 25.03 (CHMe2), 25.00 (CHMe2), 2.44
(SiMe3). IR (Nujol mull, KBr plates): 2722 (w), 2678 (w), 2624
(w), 1958 (w), 1894 (w), 1842 (w), 1606 (w), 1576 (w), 1514 (s),
1426 (s, br), 1336 (s), 1288 (s), 1244 (s), 1212 (s), 1174 (w), 1156
(s), 1110 (m), 1058 (m), 1012 (w), 980 (s), 942 (w), 918 (w), 898
(s), 842 (s), 818 (m), 786 (s), 750 (s), 720 (m), 702 (m), 672 (w),
632 (w), 594 (w), 632 (w), 516 (m), 496 (w), 446 (w) cmϪ1.
Accurate mass EI-MS for [Ti(N-2,6-iPr2C6H3){Me2NCH2CH2-
CH2NC(Ph)NSiMe3}Cl]ϩ. Found (calc. for C27H43N4ClSiTi):
m/z = 534.2433 (534.2425). Anal. found (calc. for C27H43N4-
ClSiTi): C 60.1 (60.6), H 8.3 (8.1), N 10.4 (10.5)%.
1H NMR data (C6D6, 500.0 MHz, 293 K): 7.29 (2 H, d, br,
ortho-C6H5), 7.22 (2 H, app t, meta-C6H5, app 2J = 7.8), 7.08 (1
2
2
H, t, para-C6H5, J = 7.8), 3.29 (2 H, q, CH3CH2O, J = 7.3),
3.18 (2 H, m, br, CN2CH2), 1.70 (2 H, m, br, CH3CH2), 1.13 (3
H, t, CH3CH2O, 2J = 7.3), 0.84 (3 H,s, br, CH3), 0.11 (9 H, s, br,
SiMe3). 13C-{1H} NMR data (C6D6, 75.5 MHz, 293 K): 128.10
(meta-C6H5), 127.68 (para-C6H5), 126.92 (ortho-C6H5), 66.26
(CH3CH2O), 52.92 (NCH2), 27.74 (CH3CH2), 16.20
(CH3CH2O), 12.98 (CH3), 4.14 (SiMe3). IR data (KBr plates,
Nujol mull, cmϪ1): 3584 (w), 3328 (w), 3058 (m), 3020 (m), 2730
(w), 2690 (w), 2632 (w), 2318 (w), 1946 (w), 1888 (w), 1808 (w),
1774 (w), 1622 (m), 1600 (m), 1578 (w), 1402 (s), 1138 (s), 1292
(m), 1246 (s), 1172 (m), 1148 (w), 1126 (w), 1102 (w), 1054 (s),
1018 (s), 928 (m), 876 (s), 830 (s), 1782 (m), 754 (s), 678 (w), 630
(m), 410 (s). Anal. found (calc. for C13H21LiN2Si) for Et2O-free
8: C 64.2 (65.0), H 8.7 (8.8), N 11.8 (11.6)%. A satisfactory mass
spectrum could not be obtained for this compound.
[Ti(NC6F5){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] (7)
To a stirred solution of [Ti(NtBu){Me2NCH2CH2CH2NC(Ph)-
NSiMe3}Cl] (0.98 g, 2.27 mmol) in benzene (20 ml) was added a
solution of pentafluoroaniline (0.42 g, 2.27 mmol) in benzene
(20 ml), dropwise over 10 min. The orange solution darkened in
colour. After stirring for 15 h, volatiles were removed under
reduced pressure to yield [Ti(NC6F5){Me2NCH2CH2CH2-
NC(Ph)NSiMe3}Cl] as an orange oil. Yield: 1.14 g (93%). An
analytically pure sample of 7 was obtained by sublimation at
3 × 10Ϫ6 mbar and 130 ЊC in poor yield.
[Ti(NtBu){CH3CH2CH2NC(Ph)NSiMe3}Cl(py)2] (9)
To a stirred solution of [Ti(NtBu)Cl2(py)3] (0.46 g, 1.09 mmol)
in benzene (30 ml) was added a solution of Li{CH3CH2CH2-
NC(Ph)NSiMe3}.0.5Et2O (0.30 g, 1.09 mmol) in benzene
(30 ml) dropwise over 10 min. The resulting orange mixture was
stirred for 16 h. Volatiles were removed under reduced pressure
and the resulting orange oil extracted into benzene (20 ml). The
orange oily residue was triturated with pentane (20 ml) yielding
9 as an orange solid The product was recrystallised at Ϫ80 ЊC
from a mixture of hexane (30 ml) and CH2Cl2 (20 ml). Yield:
172 mg (34%).
1H NMR data (C6D6, 500.0 MHz, 293 K): δ 7.01–7.06 (5 H,
m, br, C6H5), 2.99 (1 H, app t, CH2NMe2, app 2J = 12.7), 2.91 (2
2
H, br d, CN2CH2, J = 5.9), 2.65 (3 H, s, NMe), 1.88 (3 H, s,
2
NMe), 1.71 (1 H, br d, CH2NMe2, J = 11.7), 1.24 (1 H, m,
CH2CH2CH2), 0.85 (1 H, br d, CH2CH2CH2, 2J = 15.6), 0.16 (9
H, s, SiMe3). 13C-{1H} NMR data (C6D6, 75.5 MHz, 293 K):
177.19 (CN2), 152.43, 145.87, 142.72, 139.61, 137.35, 134.95,
133.78 (6 C of C6F5 and ipso-C6H5), 129.57 (para-C6H5), 128.79
(ortho- or meta-C6H5, 2 overlapping), 126.50 (ortho- or meta-
C6H5, 2 overlapping), 62.92 (CH2NMe2), 53.17 (NMe), 47.78
(CN2CH2), 45.72 (NMe), 26.28 (CH2CH2CH2), 2.24 (SiMe3).
19F NMR data (C6D6, 300.0 MHz, 293 K): Ϫ154.90 (2 F, ortho-
C6F5), Ϫ167.09 (2 F, meta-C6F5), Ϫ171.03 (1 F, para-C6F5). IR
data (KBr disc, cmϪ1): 2956 (s), 2924 (s), 2362 (w), 2344 (w),
1670 (w), 1618 (m, br), 1580 (w), 1522 (s), 1504 (s), 1446 (m),
1404 (m), 1392 (m), 1344 (w), 1326 (w), 1304 (w), 1246 (m, br),
1H NMR data (C6D6, 500.0 MHz, 293 K): 9.55 (2 H, d, br,
2
cis-o-C5H5N, J = 4.9), 8.67 (2 H, s, br, trans-o-C5H5N), 7.09
(2 H, m, meta-C6H5), 7.02 (3 H, m, ortho- and para-C6H5), 6.93
(1 H, s, br, trans-p-C5H5N), 6.78 (1 H, t, br, cis-p-C5H5N,
2J = 7.8), 6.63 (2 H, s, br, trans-m-C5H5N), 6.53 (2 H, app t, br,
cis-m-C5H5N, app 2J = 6.8), 3.94 (2 H, m, CN2CH2), 2.14 (2 H,
m, MeCH2), 1.42 (9 H, s, CMe3), 0.98 (3 H, t, MeCH2, 2J = 7.3),
0.14 (9 H, s, SiMe3). 13C-{1H} NMR data (C6D6, 75.5 MHz,
293 K): 165.24 (CN2), 135.93 (ipso-C6H5), 152.22 (cis-o-
C5H5N), 137.92 (cis-p-C5H5N), 129.34 (ortho- or para-C6H5),
128.55 (ortho- or para-C6H5), 126.62 (meta-C6H5), 123.62
4182
J. Chem. Soc., Dalton Trans., 2002, 4175–4184

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Table
5
X-Ray data collection and processing parameters for [Ti(NtBu){Me2NCH2CH2NC(Ph)NSiMe3}Cl] 1, [Ti(N-2,6-Me2C6H3)-
{Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] 5, [Ti(N-2,6-iPr2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] 6, [Ti(NtBu)Cl(µ-Cl){Me2NCH2CH2N᎐
᎐
C(Ph)N(H)SiMe3}]2 10 and [Ti(N-2,6-Me2C6H3)Cl(µ-O){Me2NCH2CH2N᎐C(Ph)NSiMe3}]2 11
᎐
1
5
6
10
11
Formula
Formula weight
C18H33ClN4SiTi
416.93
C23H35ClN4SiTi
479.00
C27H43ClN4SiTi
535.10
C36H68Cl4N8Si2Ti2
906.78
C44H68Cl2N8OSi2Ti2
931.96
Crystal system
Space group
Monoclinic
P21/c
Triclinic
P1
Monoclinic
P21/c
Triclinic
P1
Monoclinic
P2/n
¯
¯
a/Å
b/Å
c/Å
α/Њ
11.7460(3)
9.9836(3)
20.1557(7)
90
90.265(1)
90
2363.6(1)
4
0.53
8.8806(1)
11.2263(1)
15.0212(2)
70.6889(7)
88.3802(5)
66.8105(5)
1290.11(3)
2
0.50
11005
4948
0.0308, 0.0318
16.0613(5)
11.3483(4)
17.5211(6)
90
112.749(2)
90
2945.1(2)
4
0.433
8.8140(3)
11.6000(5)
12.6200(5)
89.420(2)
107.252(2)
105.453(2)
1184.4(1)
1
0.64
11043
4422
0.0459, 0.0348
13.9462(2)
10.0038(2)
17.9894(3)
90
96.337(1)
90
2494.45(7)
2
0.51
β/Њ
γ/Њ
V/Å3
Z
µ(Mo-Kα)/ mmϪ1
Total reflections
Observed reflectionsa
7790
3204
0.0329, 0.0366
10922
3325
0.0411, 0.0254
9895
3931
0.0351, 0.0399
Rb, Rw
c
a For reflections withI > 3σ(I); b R = Σ||Fo| – |Fc||/Σ|Fo|; c Rw = √{Σw(|Fo| – |Fc|)2/Σw|Fo|2}.
(cis-m-C5H5N), 67.46 (CMe3), 53.90 (CN2CH2), 31.30 (CMe3),
26.62 (MeCH2), 11.91 (MeCH2), 2.93 (SiMe3). IR data (KBr
plates, Nujol mull, cmϪ1): 2610 (w), 1604 (w), 1510 (w), 1444 (s),
1400 (s), 1356 (m), 1296 (w), 1244 (m), 1194 (m), 1178 (w), 1158
(w), 1070 (m), 1042 (w), 1020 (m), 1002 (w), 918 (w), 902 (m),
868 (s), 842 (s), 780 (w), 764 (m), 702 (m), 636 (s), 412 (s). A
satisfactory analysis and mass spectrum could not be obtained
for this compound.
all other non-hydrogen atoms. Carbon bound hydrogen
atoms were placed geometrically except for in 7 for which they
were located from difference syntheses and refined in a riding
model. In both 7 and 8 the H atom bound to N(4) was located
from difference syntheses and refined isotropically. Extinction
corrections21 and a weighting scheme were applied as appro-
priate. Crystallographic calculations were performed using
SIR9220 and CRYSTALS.22
CCDC reference numbers 190460–190464.
See http://www.rsc.org/suppdata/dt/b2/b207184c/ for crystal-
lographic data in CIF or other electronic format.
[Ti2{Me2NCH2CH2NC(Ph)N(H)SiMe3}2(NtBu)2Cl2(ꢀ-Cl)2] (10)
To a stirred solution of [Ti(NtBu){Me2NCH2CH2NC(Ph)-
NSiMe3}Cl] (0.113 g, 0.271 mmol) in pyridine (10 ml) was
added a solution of NH2Me2Cl (19.9 mg, 0.244 mmol) in
pyridine (20 ml) dropwise over 15 min. The resulting mixture
was refluxed at 80 ЊC for 9 h. A pure product was not isolable
upon layering with pentane, but resonances visible in the NMR
spectrum of the crystals of [Ti2{Me2NCH2CH2NC(Ph)-
N(H)SiMe3}2(NtBu)2Cl2(µ-Cl)2] were also visible in the NMR
spectrum of the crude reaction mixture.
Acknowledgements
We thank the EPSRC for support.
References and notes
1 (a) For recent reviews and leading references see: W. A. Nugent
and J. M. Mayer, Metal–Ligand Multiple Bonds, Wiley-Interscience,
New York, 1988; (b) D. E. Wigley, Prog. Inorg. Chem., 1994, 42, 239;
(c) R. R. Schrock, Acc. Chem. Res., 1990, 23, 158; (d ) P. R. Sharp,
J. Chem. Soc., Dalton Trans., 2000, 2647; (e) V. C. Gibson, Adv.
Mater., 1994, 6, 37; ( f ) Special Theme Issue Organometallic
Chemistry with N and O π-donor ligands, guest ed. P. Mountford,
J. Organomet. Chem., 1999, 591, pp. 2–213.
2 (a) See the following and references therein: P. Mountford, Chem.
Commun., 1997, 2127 (Feature Article); (b) L. H. Gade and
P. Mountford, Coord. Chem. Rev., 2001, 216–217, 65; (c) D. J. M.
Trösch, P. E. Collier, A. Bashall, L. H. Gade, M. McPartlin,
P. Mountford and S. Radojevic, Organometallics, 2001, 20, 3308;
(d ) S. A. Lawrence, M. E. G. Skinner, J. C. Green and P. Mountford,
1H NMR data (C6D6, 300.0 MHz, 293 K): δ 2.33 (6 H, s,
NMe2), 1.27 (9 H, s, CMe3), Ϫ0.03 (9 H, s, SiMe3). Assignment
of other peaks not possible due to overlaps with impurities. IR
data (KBr plates, Nujol mull, cmϪ1): 3268 (w), 2955 (m), 1608
(w), 1590 (m), 1574 (m), 1494 (w), 1353 (m), 1342 (w), 1288 (m),
1244 (m), 1208 (w), 1171 (w), 1147 (w), 1123 (w), 1081 (m), 1060
(m), 1037 (w), 1007 (m), 953 (m), 932 (m), 846 (s), 797 (m), 770
(m), 757 (m), 733 (m), 709 (m), 626 (w), 597 (w), 565 (w),
525 (w), 471 (w), 448 (w) cmϪ1. Anal. found (calc. for
C36H68Cl4N8Si2Ti2): C 46.6 (47.7), H 8.0 (7.6), N 11.8 (12.4)%.
Crystal structure determinations for [Ti(NtBu){Me2NCH2CH2-
NC(Ph)NSiMe3}Cl] (1), [Ti(N-2,6-R2C6H3){Me2NCH2CH2-
CH2NC(Ph)NSiMe3}Cl] (R ؍ Me 5 or iPr 6), [Ti2{Me2NCH2-
Chem. Commun., 2001, 705; (e) N. Adams, A.
R Cowley,
S. R Dubberley, A. J. Sealey, M. E. G. Skinner and P. Mountford,
Chem. Commun., 2001, 2738; ( f ) A. J. Blake, P. E. Collier,
L. H. Gade, J. Lloyd, P. Mountford, S. M. Pugh, M. Schubart,
M. E. G. Skinner and D. J. M. Trösch, Inorg. Chem., 2001, 40, 870.
3 (a) For reviews see: J. Barker and M. Kilner, Coord. Chem. Rev.,
1994, 133, 219; (b) F. T. Edelmann, Coord. Chem. Rev., 1994, 137,
403.
4 (a) For recent work with Group 4, non-imido systems see the
following and references therein: R. J. Keaton, L. A. Koterwas,
J. C. Fettinger and L. R. Sita, J. Am. Chem. Soc., 2002, 124, 5932;
(b) J. R. Hagadorn and J. Arnold, Organometallics, 1998, 17, 1355;
(c) R. Gómez, R. Duchateau, A. N. Chernega, A. Meetsma, F. T.
Edelmann, J. H. Teuben and M. L. H. Green, J. Chem. Soc., Dalton
Trans., 1995, 217.
CH N᎐C(Ph)N(H)SiMe } (NtBu) Cl (ꢀ-Cl) ] (10) and [Ti (N-
᎐
2
3
2
2
2
2
2
2,6-C H Me ) Cl (ꢀ-O){Me NCH CH N᎐C(Ph)N(H)SiMe } ]
᎐
6
3
2
2
2
2
2
2
3 2
(11)
Crystal data collection and processing parameters are given in
Table 5. Crystals were immersed in a film of perfluoropolyether
oil on a glass fibre and transferred to an Enraf-Nonius DIP2000
or KappaCCD diffractometer equipped with an Oxford Cryo-
systems low-temperature device.18 Data were collected at low
temperature using Mo-Kα radiation; equivalent reflections
were merged and the images were processed with the DENZO
and SCALEPACK programs.19 Corrections for Lorentz-
polarisation effects and absorption were performed and the
structures were solved by direct methods using SIR92.20 Sub-
sequent difference Fourier syntheses revealed the positions of
5 P. J. Stewart, A. J. Blake and P. Mountford, Inorg. Chem., 1997, 36,
3616.
6 (a) P. J. Stewart, A. J. Blake and P. Mountford, Organometallics,
1998, 17, 3271; (b) P. J. Stewart, A. J. Blake and P. Mountford,
J. Organomet. Chem., 1998, 564, 209.
J. Chem. Soc., Dalton Trans., 2002, 4175–4184
4183

View Article Online
7 A. E. Guiducci, A. R. Cowley, M. E. G. Skinner and P. Mountford,
J. Chem. Soc., Dalton Trans., 2001, 1392.
8 (a) M. J. R. Brandsma, E. A. C. Brussee, A. Meetsma, B. Hessen and
J. H. Teuben, Eur. J. Inorg. Chem., 1998, 1867; (b) S. Bambirra,
A. Meetsma, B. Hessen and J. H. Teuben, Organometallics, 2000, 19,
3197.
13 For a discussion and leading references see: N. Kaltsoyannis and
P. Mountford, J. Chem. Soc., Dalton Trans., 1999, 781.
14 (a) F. H. Allen and O. Kennard, Chem. Des. Autom. News, 1993,
8, 1–31; (b) The United Kingdom Chemical Database Service,
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18 J. Cosier and A. M. Glazer, J. Appl. Crystallogr., 1986, 19, 105.
19 D. Gewirth, The HKL Manual, written with the co-operation of the
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10 Arnold has reported Mg, Al, Zr and La complexes of the pendant
pyridyl donor substituted amidinate ligands (2-NC5H4)CH2-
CH2NC(4-C6H4R)NRЈ (R, RЈ = Me, Ph or tBu, 3,5-Me2C6H3):
K. Kincaid, C. P. Gerlach, G. R. Giesbrecht, J. R. Hagadorn,
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11 (a) Although for ease of representation all titanium imido linkages
are drawn “Ti᎐NR”, the formal titanium imido nitrogen bond order
᎐
in the complexes described herein is probably best thought of
as closer to three (pseudo-σ2 π4; triple bond) rather than as two:
T. R. Cundari, Chem. Rev., 2000, 100, 807; (b) N. Kaltsoyannis and
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therein.
20 A. Altomare, G. Cascarano, G. Giacovazzo, A. Guagliardi,
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21 A. C. Larson, Acta Crystallogr., 1967, 23, 664.
22 D. J. Watkin, C. K. Prout, J. R. Carruthers and P. W. Betteridge,
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12 A. J. Blake, P. E. Collier, S. C. Dunn, W.-S. Li, P. Mountford and
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4184
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