New binuclear alkyl and half-sandwich cyclopentadienyl imido titanium complexes containing acetamidinate and benzamidinate supporting ligands

Article abstract of DOI:10.1016/S0022-328X(98)00645-7

Chloride metathesis reactions of the binuclear titanium N,N′-bis(cyclohexyl)acetamidinato-μ-imido compound [Ti₂(μ-NBu^t)₂{MeC(NC₆H₁₁)₂}₂Cl₂] (1) and the mononuclear N,N

Full text of DOI:10.1016/S0022-328X(98)00645-7

Journal of Organometallic Chemistry 564 (1998) 209–214
New binuclear alkyl and half-sandwich cyclopentadienyl imido
titanium complexes containing acetamidinate and benzamidinate
supporting ligands
Peter J. Stewart, Alexander J. Blake, Philip Mountford 1,*
Department of Chemistry, Uni6ersity of Nottingham, Nottingham, NG7 2RD, UK
Received 20 March 1998
Abstract
Chloride metathesis reactions of the binuclear titanium N,N%-bis(cyclohexyl)acetamidinato-v-imido compound [Ti2(v-
NBut)2{MeC(NC6H11)2}2Cl2] (1) and the mononuclear N,N%-bis(trimethylsilyl)benzamidinato-imido analogue [Ti(N-
But){PhC(NSiMe3)2}Cl(py)2] (2) are described. Thus, reaction of 1 or 2 with LiC5R5 (R=H or Me) gave the half-sandwich
compounds [Ti(NBut){MeC(NC6H11)2}(p-C5H5)] and [Ti(NBut){PhC(NSiMe3)2}(p-C5Me5)], respectively. These compounds are
also accessible from [Ti(NBut)(p-C5R5)Cl(L)] (R=H or Me; L=py or 4-NC5H4But) and the appropriate lithium amidinate.
Treatment of 1 with MeLi gave the binuclear 12-electron methyl derivative [Ti2(v-NBut)2{MeC(NC6H11)2}2(Me)2] which has been
crystallographically characterised. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Titanium; Imide; Benzamidinate; Acetamidinate; Cyclopentadienyl; X-ray diffraction
1. Introduction
aryl and R% is alkyl, aryl or trimethylsilyl) ligand are
very well-established [7–10]. Furthermore, since there is
much current interest in developing non-metallocene
early transition metal chemistry [11–15], we were inter-
ested to explore the potential of the amidinate-imide
ligand set for supporting new organometallic complexes
of titanium. The trianionic net charge for the
{[RC(NR)2](NR)} moiety is an alternative to the well-
known dianionic bis(cyclopentadienyl), tetraazamacro-
cyclic, Schiff-base, diamide, and cyclopentadienyl-
amide moeties [11–17]. Here we describe new amidi-
nato-imido chemistry of titanium which thus far has
been largely dominated by compounds with one or two
cyclopentadienyl co-ligands [18].
As part of an ongoing study of titanium imido
chemistry [1] we recently described the synthesis and
structures of [Ti2(v-NR)2{MeC(NC6H11)2}2Cl2] (1) and
[Ti(NBut){PhC(NSiMe3)2}Cl(py)2] (R=But 2 or aryl)
[2]. These compounds contain the unusual amidinate-
imide ligand set. This is a very recently reported ligand
combination [2–6], and has not yet been exploited to
any significant extent as a supporting environment for
new transition metal chemistry. We thought this sur-
prising since the chemistry of compounds containing
either the imide (NR, where typically R is alkyl or aryl)
or amidinate (RC(NR%)2 where usually R is H, alkyl or
* Corresponding author. Tel.: +44 115 9513513; fax: +44 115
9513563; e-mail: Philip.Mountford@Nottingham.ac.uk
2. Results and discussion
1 Philip Mountford is the Royal Society of Chemistry Sir Edward
The starting compounds [Ti2(v-NBut)2{MeC(NC6-
H11)2}2Cl2] (1) and [Ti(NBut){PhC(NSiMe3)2}Cl(py)2]
Frankland
Fellow
(WWW:
http://www.nottingham.ac.uk/ꢀ
pczwww/Inorganic/Pmount.html).
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00645-7

210
P.J. Stewart et al. / Journal of Organometallic Chemistry 564 (1998) 209–214
Scheme 1. Reagents and conditions: (i) LiC5H5, C6D6, r.t. then 60°C, 6 days, \95%; (ii) LiMeC(NC6H11)2, toluene, −50°C then r.t., 18 h, 97%;
(iii) MeLi, Et2O/THF, −60°C then r.t., 2 h, 67%; (iv) LiC5Me5, toluene, 90°C, 66 h, 79%; (v) LiPhC(NSiMe3)2, C6D6, r.t., 23 h, \95%.
(2, Scheme 1) were prepared as recently reported [2]
by treatment of [Ti(NBut)Cl2(py)3] [19] with
LiMeC(NC6H11)2 [20] or LiPhC(NSiMe3)2 [21,22], re-
spectively. The half-sandwich complexes [Ti(NBut)(p-
C5R5)Cl(L)] (R=H or Me; L=py or 4-NC5H4But)
were prepared from the appropriate LiC5R5 and [Ti(N-
But)Cl2(4-NC5H4But)2] or [Ti(NBut)Cl2(py)3] [23].
The new half-sandwich N,N’-bis(cyclohexyl)aceta-
midinate-imido complex [Ti(NBut){MeC(NC6H11)2}(p-
[23]. Unfortunately all attempts to crystallise 3 were
unsuccessful. An NMR scale reaction demonstrated
that compound 3 could also be obtained by treatment
of [Ti2(v-NBut)2{MeC(NC6H11)2}2Cl2] (1) with two
equivalents of LiC5H5 in C6D6.
In order to obtain a solid sample of this new class of
complex we prepared a benzamidinate analogue of 3.
Thus reaction of one equivalent of LiC5Me5 with [Ti(N-
But){PhC(NSiMe3)2}Cl(py)2] 2 in toluene at 90°C gave
the pentamethylcyclopentadienyl derivative [Ti(N-
But){PhC(NSiMe3)2}(p-C5Me5)] (4) as a red, waxy solid
in 79% yield after high vacuum sublimation (120–
C5H5)] (3 in Scheme 1) was obtained as
a
spectroscopically pure red oil in 97% yield via reaction
of LiMeC(NC6H11)2 with [Ti(NBut)(p-C5H5)Cl(py)]

P.J. Stewart et al. / Journal of Organometallic Chemistry 564 (1998) 209–214
211
160°C, 2×10−5 mbar). An NMR scale reaction
showed that 4 was also accessible by reaction of one
equivalent of LiPhC(NSiMe3)2 with [Ti(NBut)(p-
C5Me5)Cl(4-NC5H4But)] in C6D6. This reaction pro-
ceeds slowly, probably due to the steric bulk of the
ligands involved and the limited solubility of LiC5Me5
in C6D6.
The new half-sandwich compounds are proposed to
possess the 16-electron, monomeric structures illus-
trated in Scheme 1 and, to the best of our knowledge,
are the first examples of this particular combination of
ligand sets. The compounds 3 and 4 may be compared
with the bis(cyclopentadienyl) complexes [Ti(p-
C5H5)(p-C5R5)(NBut)(L)] (R=H or Me, L=py or
NC5H4But) and the cyclopentadienyl-indenyl complex
[Ti(p-C5H5)(p-C9H7)(NBut)(py)], all of which exist as
pyridine adducts [23]. It appears therefore that the
amidinate ligand in 3 and 4 has greater steric demands
than those of the p-cyclopentadienyl or -indenyl lig-
ands; this is consistent with previous work [24]. Other
(non-imido) group 4 compounds containing the cy-
clopentadienyl-amidinate ligand set have been described
previously [25].
refined in an isotropic model. The titanium to methyl
hydrogen distances (2.55(8), 2.59(8), 2.59(8) A) are
˚
normal (i.e. not indicative of an h-agostic interaction
with Ti [27,28]) and also equivalent within one standard
deviation. The Ti(1)–C(19)–H angles are also equiva-
lent and have normal values. Furthermore, the Ti–
˚
C(methyl) bond length of 2.160(6) A is slightly longer
˚
than average for a such bonds (average 2.143 A for 53
examples) [29,30], and not the relatively shortened dis-
tance that might be expected if there were h-agostic
interactions in this 12-electron compound [27].
The
r.t.
1H-NMR
spectrum
of
[Ti2(v-
NBut)2{MeC(NC6H11)2}2(Me)2] in benzene-d6 shows
several broad cyclohexyl resonances; the methyl group
attached to titanium appears as a singlet at 1.35 ppm.
The equivalence of the cyclohexyl methine resonances
indicates that this complex is fluxional at r.t. since the
two rings are inequivalent in the solid state (see Fig. 1).
The limited solubility of 5 in non-halogenated solvents
Table 1
X-ray data collection and processing parameters for [Ti2(v-
NBut)2{MeC(NC6H11)2}2(Me)2]·C6H14 (5·C6H14
)
We were also interested to prepare alkyl complexes
supported by amidinate-imide ligands. Accordingly, re-
action of [Ti2(v-NBut)2{MeC(NC6H11)2}2Cl2] (1), with
MeLi in Et2O/THF at −60°C gave, after standard
workup and recrystallisation from hexane, orange-red
diffraction-quality crystals of the binuclear, 12-electron
dimer [Ti2(v-NBut)2{MeC(NC6H11)2}2(Me)2] (5) in 67%
yield. Details of data collection and processing are
given in Table 1. Attempts to prepare titanium methyl
complexes with benzamidinate supporting ligands were
unsuccessful.
Molecular formula
Formula weight
Temperature (K)
Crystal system
C38H74N6Ti2 ·C6H14
797.00
220(2)
Triclinic
(
Space group
P1 (No. 2)
Unit cell dimensions
˚
a (A)
10.359(2)
10.5974(9)
11.097(1)
93.404(9)
100.12(1)
87.84(1)
1196.7(3)
1
˚
b (A)
˚
c (A)
h (°)
i (°)
k (°)
3
˚
Volume (A )
A
view of the molecular structure of [Ti2(v-
Z
NBut)2{MeC(NC6H11)2}2(Me)2] (5) is shown in Fig. 1
and important bond lengths and angles are listed in
Table 2. Compound 5 possesses a crystallographically
centrosymmetric, binuclear geometry which is very sim-
ilar to that of [Ti2(v-NBut)2{MeC(NC6H11)2}2Cl2] (1)
[2]. There is disordered hexane of crystallisation in the
lattice of 5·C6H14 and this was satisfactorily modelled.
Density (calculated) (mg m−3
)
)
1.11
0.36
438
Absorption coefficient (mm−1
F(000)
Crystal description and size
(mm)
Theta range for data collection 2.61–23.51
(°)
Scan type
Index ranges
Red plate, 0.34×0.19×0.06
ꢀ-q
−115h511, −115k511,
−85l512
3541
2577
None
˚
The Ti…Ti separation of 2.803(2) A in 5 is comparable
to that of 1, but the difference between the two Ti–v-
Independent reflections
Observed reflections [I\2|(I)]
Absorption correction
Variation in standard
reflections
˚
N(imido) bond lengths (0.109(7) A for 5) is less
˚
(0.162(4) A for 1). The titanium–N(amidinate) bonds
˚
Random93.8%
(2.160(5) and 2.105(5) A) in 5 are longer than those of
˚
1 (2.112(3) and 2.076(3) A), possibly because the methyl
Data/restraints/parameters
Refinement method
2577/10/253
Blocked-matrix least squares on
F
Unit weights
R=0.0798, Rw=0.0873
1.545
0.05
0.46 and −0.48
ligand is a better and less electronegative donor than
chloride. A 14-electron, binuclear analogue of 5,
namely the cyclopentadienyl v-imido-alkyl compound
[Ti2(v-NPh)2(p-C5H5)2(Me)2] was reported by Teuben
some time ago [26] but was not crystallographically
characterised.
Weighting scheme
Final R indicesa [I\2|(I)]
Goodness-of-fit
Final (D/|)max
Largest residual peaks (e A
−3
˚
)
The H atoms of the methyl ligand were located from
Fourier difference syntheses and were positionally
a R=R1=ꢀꢁꢁFoꢁ−ꢁFcꢁꢁ/ꢀꢁFoꢁ; Rw=ꢂ{ꢀw(ꢁFoꢁ−ꢁFcꢁ)2/ꢀwꢁFoꢁ }.
2

212
P.J. Stewart et al. / Journal of Organometallic Chemistry 564 (1998) 209–214
pared to those of their non-metallated counterparts is
well known.
3. Experimental section
All manipulations were carried out under an atmo-
sphere of dinitrogen or argon using standard Schlenk-
line or dry-box techniques. All protio-solvents and
commercially-available reagents were pre-dried over ac-
tivated molecular sieves and refluxed over an appropri-
ate drying agent under an atmosphere of dinitrogen and
collected by distillation. CDCl3 was dried over freshly
ground calcium hydride at r.t. and C6D6 was dried over
molten potassium. All NMR solvents were distilled
under reduced pressure and stored under N2 in a J.
Young ampoule. NMR samples were prepared in the
dry-box in 5 mm Wilmad tubes equipped with a
Young’s Teflon valve.
Fig. 1. Displacement ellipsoid (30%) plot of [Ti2(v-
NBut)2{MeC(NC6H11)2}2(Me)2] (5). Hydrogen atoms and the hexane
molecule of crystallisation are omitted. Atoms carrying the suffix ‘B’
are related to their non-suffixed counterparts by the symmetry opera-
tor [1−x, −y, 2−z].
1H and 13C spectra were recorded on a Bruker DPX
300 spectrometer and referenced internally to residual
protio-solvent (1H) or solvent (13C) resonances. Chemi-
cal shifts are reported relative to tetramethylsilane (l=
0 ppm) in l (ppm) and coupling constants in Hz.
Assignments were supported by DEPT-135 and DEPT-
90, homo- and hetero-nuclear, one- and two-dimen-
sional experiments as appropriate. IR spectra were
recorded on a Nicolet 205 FTIR spectrometer in the
range 400–4000 cm−1. Samples were prepared in the
dry-box between KBr or CsBr plates as Nujol mulls or
as thin films and data are quoted in wavenumbers (w,
cm−1). Elemental analyses were carried out by the
analysis laboratory of this department.
Li[PhC(NSiMe3)2] [21,22], Li[MeC(NC6H11)2] [20],
[Ti2(v-NBut)2{MeC(NC6H11)2}2Cl2] (1) [2], [Ti(N-
But){PhC(NSiMe3)2}Cl(py)2] (2) [2], and [Ti(NBut)(p5-
C5R5)Cl(L)] (R=H or But; L=py or 4-NC5H4But) [23]
were prepared according to literature methods. LiC5R5
(R=H or Me) was prepared from n-butyllithium and
C5R5H in cold hexanes.
hindered attempts to record low temperature spectra.
Interestingly, the gated decoupled 13C-NMR spectrum
at 25°C shows a binomial quartet for the titanium-
bound methyl carbon at l=41.9 ppm with an averaged
1JCH coupling constant of ca. 120 Hz which in the range
previously suggested to be consistent with agostic inter-
actions [27]. However, the absence of a low w(C–H)
absorption in the IR spectrum of 5 and of a close
Ch–H–Ti contact in the solid state structure militates
against a significant h-agostic interaction of the methyl
1
group with titanium. Moreover, the lowering of JCH
values for carbons bound to electropositive metals com-
Table 2
˚
Selected bond lengths (A) and angles (°) for [Ti2(v-
NBut)2{MeC(NC6H11)2}2(Me)2] (5). Atoms carrying the suffix ‘B’ are
related to their counterparts by the symmetry operator [1−x, −y,
2−z]
3.1. [Ti(NBut){MeC(NC6H11)2}(p-C5H5)] (3)
Ti(1)…Ti(1B)
Ti(1)–N(1)
Ti(1)–N(1B)
Ti(1)–N(2)
Ti(1)–N(3)
2.803(2) Ti(1)–C(19)
1.860(5) N(1)–C(1)
1.969(5) Ti(1)…H(191)
2.160(5) Ti(1)…H(192)
2.105(5) Ti(1)…H(193)
2.160(6)
1.481(8)
2.55(8)
2.59(8)
2.59(8)
Cold (−50°C) toluene (25 ml) was added slowly to a
mixture of [Ti(NBut)(p-C5H5)Cl(py)] (0.585 g, 1.96
mmol) and LiMeC(NC6H11)2 (0.568 g, 1.96 mmol). The
resulting red solution was allowed to warm to r.t.,
stirred for 18 h then filtered. Volatiles were removed
under reduced pressure to yield 3 as a red oil which
could not be crystallised. Yield: 0.77 g (97%).
Ti(1B)…Ti(1)–N(1)
44.5(2)
Ti(1)…Ti(1B)–C(19) 106.6(2)
Ti(1B)…Ti(1)–N(1B) 41.4(2)
N(1)–Ti(1)–C(19)
N(1B)–Ti(1)–C(19)
105.5(3)
98.8(2)
89.6(2)
139.8(2)
94.1(2)
N(1)–Ti(1)–N(1B)
Ti(1B)…Ti(1)–N(2)
N(1)–Ti(1)–N(2)
N(1B)–Ti(1)–N(2)
Ti(1B)…Ti(1)–N(3)
N(1)–Ti(1)–N(3)
N(1B)–Ti(1)–N(3)
N(2)–Ti(1)–N(3)
85.9(2)
157.7(2) N(2)–Ti(1)–C(19)
117.0(2) N(3)–Ti(1)–C(19)
152.6(2) Ti(1)–N(1)–Ti(1B)
109.6(2) Ti(1)–C(19)–H(191) 105(5)
112.4(2) Ti(1)–C(19)–H(192) 112(6)
1H-NMR (CDCl3, 300.1 MHz, 25°C): 6.35 (s, 5H,
C5H5), 3.31 (t of t, J=10.6 and 3.7 Hz, 2H,
NCHC5H10), 2.01 (s, 3H, MeCN2), 1.80 to 0.92 (series
of multiplets, 20H, NCHC5H10), 0.94 (s, 9H, NBut).
13C{1H}-NMR (CDCl3, 75.5 MHz, 25°C): 158.8
(MeCN2), 110.1 (C5H5), 66.8 (NCMe3), 56.6
96.7(2)
61.8(2)
Ti(1)–C(19)–H(193) 107(5)

P.J. Stewart et al. / Journal of Organometallic Chemistry 564 (1998) 209–214
213
(NCHC5H10), 36.6, 36.1 (2×NCHC5H10), 32.4
(NCMe3), 26.0, 25.7, 25.5 (3×NCHC5H10), 10.9
(MeCN2). IR (KBr plates, thin film): 3102 (w), 2959 (s),
2926 (vs), 2851 (s), 2666 (w), 1763 (w), 1664 (w), 1491
(s), 1449 (s), 1418 (m), 1360 (s), 1348 (s), 1307 (w), 1244
(s), 1211 (s), 1182 (w), 1141 (w), 1120 (w), 1093 (m),
1050 (w), 1013 (m), 953 (w), 922 (w), 887 (w), 861 (w),
843 (w), 826 (w), 788 (s), 777 (s), 673 (w), 616 (w), 595
(w), 537 (m), 507 (w) cm−1. Satisfactory elemental
analysis was not obtained for this compound, which
was an oil.
0.041 mmol) in C6D6 (0.6 ml) was transfered to a 5 mm
J. Young NMR tube. The H-NMR spectrum after 23
h at r.t. showed quantitative formation of [Ti(N-
But){PhC(NSiMe3)2}(p-C5Me5)] (5) together with new
resonances attributable to free 4-NC5H4But.
1
3.5. [Ti2(v-NBut)2{MeC(NC6H11)2}2(Me)2] (5)
MeLi (0.19 ml of 1.4 M solution in Et2O, 0.27 mmol)
was added to
a
stirred solution of [Ti2(v-
NBut)2{MeC(NC6H11)2}2Cl2] (0.096 g, 0.13 mmol) in
THF (20 ml) at −60°C. The resulting red solution was
allowed to warm to r.t. then stirred for a further 2 h.
The volatiles were removed under reduced pressure and
the solid residue was redissolved in warm hexane (30
ml, 50°C) and filtered. Concentration to 20 ml then
cooling to r.t. afforded 5 as orange-red crystals
overnight. These were washed with cold hexane (2×5
ml) and dried in vacuo. Yield: 0.061 g (67%).
3.2. NMR tube synthesis of 3 from
[Ti2(v-NBut)2{MeC(NC6H11)2}2Cl2] and LiC5H5
A solution of [Ti2(v-NBut)2{MeC(NC6H11)2}2Cl2] (1)
(5.1 mg, 0.007 mmol) and LiC5H5 (1 mg, 0.014 mmol)
in C6D6 (0.6 ml) was transfered to a 5 mm J. Young
1
NMR tube. The H-NMR spectra over 5 days showed
slow
formation
(15%
complete)
of
[Ti(N-
1H-NMR (C6D6, 300.1 MHz, 25°C): 3.57 (m, 4H,
NCHC5H10), 1.82 (s, 6H. MeCN2), 2.1 to 1.0 (40H,
series of multiplets corresponding to NCHC5H10 of two
pairs of inequivalent cyclohexyl rings), 1.53 (s, 18H,
NBut), 1.35 (s, 6H, Ti–Me). 13C{1H}-NMR (C6D6,
75.5 MHz, 25°C): 178.6 (MeCN2), 69.7 (NCMe3), 58.8
(NCHC5H10), 41.9 (q, 1JCH=120 Hz, Ti–Me), 35.4
(2×NCHC5H10), 32.6 (NCMe3), 26.9 (overlapping 2×
NCHC5H10), 26.3 (1×NCHC5H10), 14.1 (MeCN2);
note: 1J for the l=41.9 Ti–Me resonance was ob-
tained from a gated-coupled 13C-NMR spectrum of 5 in
the same solvent and at the same temperature. IR (KBr
plates, Nujol mull): 1716 (w), 1652 (m), 1491 (m), 1356
(s), 1313 (w), 1257 (m), 1192 (s), 1181 (s), 1138 (w),
1094 (m), 1078 (m), 1027 (m), 1002 (m), 890 (w), 800
(m), 766 (w), 744 (w), 722 (w), 700 (w), 668 (w), 648
(vs), 607 (w), 590 (w), 557 (w), 549 (w), 542 (w) cm–1.
Anal. Found (calculated for C38H74N6Ti2: C, 63.3
(64.2); H, 10.5 (10.5); N, 11.6 (11.8)%. The low %C
found for this compound may be attributed to poor
combustion and titanium carbide formation.
But){MeC(NC6H11)2}(p5-C5H5)] (3). The reaction went
to completion when the solution was heated at 60°C for
24 h.
3.3. [Ti(NBut){PhC(NSiMe3)2}(p-C5Me5)] (4)
An orange solution of LiC5Me5 (0.053 g, 0.37 mmol)
and [Ti(NBut){PhC(NSiMe3)2}Cl(py)2] (0.214 g, 0.37
mmol) in toluene (40 ml) was refluxed at 90°C under
reduced pressure in a J. Young ampoule for 66 h. After
cooling, the resulting red solution was filtered and
volatiles were removed under reduced pressure to leave
4 as a red oil. Sublimation at 120–160°C, 2×10−5
mbar onto a cold finger at −78°C gave 4 as a red waxy
solid. Yield: 0.152 g (79%).
1H-NMR (CDCl3, 300.1 MHz, 25°C): 7.38, (m, 3H,
ortho- and para-C6H5), 7.28, (m, 2H, meta-C6H5), 2.14
(s, 15H, C5Me5), 1.00 (s, 9 H, NBut), −0.10 (s, 18H,
SiMe3). 13C{1H}-NMR (CDCl3, 75.5 MHz, 25°C):
173.1 (C6H5CN2), 139.5 (ipso-C6H5), 128.3, 128.2, 127.6
(ortho-, meta- and para-C6H5), 119.4 (C5Me5), 67.1
(NCMe3), 32.5 (NCMe3), 12.4 (C5Me5), 3.0 (SiMe3). IR
(CsBr plates, Nujol mull): 1654 (w), 1246 (s), 1206 (w),
1004 (m), 994 (m), 841 (vs), 762 (m), 722 (w), 702 (w),
541 (w), 506 (w), 412 (w) cm−1. Anal. Found (calcu-
lated for C27H47N3Si2Ti): C, 61.0 (62.6); H, 9.2 (9.2); N,
7.6 (8.1)%. The low %C and %N found for this com-
pound may be attributed to poor combustion and
titanium carbide and/or nitride formation.
3.6. Crystal structure determination of
[Ti2(v-NBut)2{MeC(NC6H11)2}2(Me)2] ·C6H14
(5 ·C6H14)
Crystal data collection and processing parameters are
given in Table 1. A crystal was mounted in a film of
RS3000 perfluoropolyether oil (Hoechst) on a glass
fibre and transferred to a Stoe¨ Stadi-4 four-circle dif-
fractometer equipped with an Oxford Cryosystems low-
temperature device [31]. Data were collected using
3.4. NMR tube synthesis of 4 from
[Ti(NBut)(p-C5Me5)Cl(4-NC5H4But)] and
LiPhC(NSiMe3)2
˚
Mo–Kh radiation (u=0.71073 A). No absorption cor-
rection was applied to the data. Equivalent reflections
were merged and the structure was solved by direct
methods using SIR92 [32]. Subsequent difference
Fourier syntheses revealed the positions of all other
A solution of [Ti(NBut)(p-C5Me5)Cl(4-NC5H4But)]
(16.9 mg, 0.040 mmol) and LiPhC(NSiMe3)2 (11.2 mg,

214
P.J. Stewart et al. / Journal of Organometallic Chemistry 564 (1998) 209–214
[4] M.H. Ribeiro da Costa, M.T. Avilez, J.H. Teuben, unpublished
results cited in [9].
[5] P.J. Stewart, A.J. Blake, P. Mountford, Inorg. Chem. 36 (1997)
1982.
non-hydrogen atoms. Non-H atoms of [Ti2(v-
NBut)2{MeC(NC6H11)2}2(Me)2] were refined anisotropi-
cally. Residual electron density was modelled as a
hexane molecule (there is one hexane molecule per
[Ti2(v-NBut)2{MeC(NC6H11)2}2(Me)2] dimer) disor-
dered across a crystallographic inversion centre. The
non-H atoms of this solvate were refined isotropically
with similarity restraints applied to C–C distances and
C–C–C angles. Hydrogen atoms for [Ti2(v-
NBut)2{MeC(NC6H11)2}2(Me)2] were located from
Fourier difference syntheses. Those for the hexane
molecule of crystallisation were placed geometrically.
All H atoms were refined in a riding model, except for
those of the titanium–methyl carbon [C(19)] which
were positionally refined with a common Uiso value.
The H atoms for the tert-butyl methyl groups, the
amidinate methyl group, the two cyclohexyl rings were
assigned common Uiso values which were refined. Data
were collected to only qmax=23.5° since there were no
detectable diffraction peaks beyond this point. At-
tempted F2 refinement on all data gave unstable results
and so this structure was refined on F with data selected
above the I\2|(I) threshold. Examination of the
refined extinction parameter and an agreement analysis
suggested that no extinction correction was required.
All crystallographic calculations were performed using
SIR92 and CRYSTALS-PC [33].
[6] D.Y. Dawson, J. Arnold, Organometallics 16 (1997) 1111.
[7] W.A. Nugent, J.M. Mayer (Eds), Metal-Ligand Multiple Bonds,
Wiley, New York, 1988.
[8] D.E. Wigley, Prog. Inorg. Chem. 42 (1994) 239.
[9] F.T. Edelmann, Coord. Chem. Rev. 137 (1994) 403.
[10] J. Barker, M. Kilner, Coord. Chem. Rev 133 (1994) 219.
[11] M.P. Coles, C.I. Dalby, V.C. Gibson, W. Clegg, M.R.J. Else-
good, J. Chem. Soc., Chem. Commun. (1995) 1709.
[12] F.G.N. Cloke, T.J. Geldbach, P.B. Hitchcock, J.D. Love, J.
Organomet. Chem. 506 (1996) 343.
[13] J.D. Scollard, D.H. McConville, S.J. Rettig, Organometallics 16
(1997) 1810.
[14] D.G. Black, R.F. Jordan, R.D. Rogers, Inorg. Chem. 36 (1997)
103.
[15] P. Mountford, Chem. Soc. Rev. 27 (1998) 105.
[16] M. Bochmann, J. Chem. Soc., Dalton Trans. (1996) 255.
[17] H.H. Brintzinger, D. Fischer, R. Mu¨lhaupt, B. Rieger, R.M.
Waymouth, Angew. Chem. Int. Ed. Engl. 34 (1995) 1143.
[18] M. Bochmann, in: E.W. Abel, F.G.A. Stone, G. Wilkinson
(Eds.), Comprehensive Organometallic Chemistry II, vol. 4, El-
sevier, New York, 1995, p. 273.
[19] A.J. Blake, P.E. Collier, S.C. Dunn, W.-S. Li, P. Mountford,
O.V. Shishkin, J. Chem. Soc., Dalton Trans. (1997) 1549.
[20] S. Hao, P. Berno, R.K. Minhas, S. Gambarotta, Inorg. Chim.
Acta 244 (1996) 37.
[21] R.T. Boere´, R.T. Oakley, R.W. Reed, J. Organomet. Chem. 331
(1987) 161.
[22] M. Wedler, F. Kno¨sel, M. Noltemeyer, F.T. Edelmann, U.
Behrens, J. Organomet. Chem. 388 (1990) 21.
[23] S.C. Dunn, P. Mountford, D.A. Robson, J. Chem. Soc., Dalton
Trans. (1997) 293.
[24] R. Duchateau, C.T. van Wee, A. Meetsma, P.T. van Duijnen,
J.H. Teuben, Organometallics 15 (1996) 2279.
[25] R. Go´mez, R. Duchateau, A.N. Chernega, A. Meetsma, F.T.
Edelmann, J.H. Teuben, M.L.H. Green, J. Chem. Soc., Dalton
Trans. (1995) 217.
[26] C.T. Vroegop, J.H. Teuben, F. van Bolhuis, J.G.M. van der
Linden, J. Chem. Soc., Chem. Commun. (1983) 550.
[27] M. Brookhart, M.L.H. Green, L.-L. Wong, Prog. Inorg. Chem.
36 (1988) 1.
Acknowledgements
This work was supported by grants (to PM) from the
EPSRC, Leverhulme Trust and Royal Society. We
thank the EPSRC for a studentship (to PJS) and the
provision of an X-ray diffractometer. We are also very
grateful to Dr W.-S. Li for help with the X-ray data
acquisition. We acknowledge the use of the EPSRC
Chemical Database Service at Daresbury Laboratory.
[28] Z. Dawoodi, M.L.H. Green, V.S.B. Mtetwa, K. Prout, A.J.
Schultz, J.M. Williams, T.F. Koetzle, J. Chem. Soc., Dalton
Trans. (1986) 1629.
[29] F.H. Allen, O. Kennard, Chemical Design Automation News 8
(1993) 1, 31.
References
[30] D.A. Fletcher, R.F. McMeeking, D. Parkin, J. Chem. Inf.
Comput. Sci. 36 (1996) 746.
[31] J. Cosier, A.M. Glazer, J. Appl. Crystallogr. 19 (1986) 105.
[32] A. Altomare, G. Cascarano, G. Giacovazzo, A. Guagliardi,
M.C. Burla, G. Polidori, M. Camalli, J. Appl. Crystallogr. 27
(1994) 435.
[1] (a) P. Mountford, Chem. Commun. (1997) 2127 (Feature Arti-
cle). (b) P.J. Wilson, A.J. Blake, P. Mountford, M Schro¨der,
Chem. Commun. (1998) 1007. (c) A.J. Blake, S.C. Dunn, J.C.
Green, N.M. Jones, A.G. Moody, P. Mountford, Chem. Com-
mun. (1998) 1235.
[2] P.J. Stewart, A.J. Blake, P. Mountford, Inorg. Chem. 36 (1997)
3616.
[3] J.R. Hagadorn, J. Arnold, J. Am. Chem. Soc. 118 (1996) 893.
[33] D.J. Watkin, C.K. Prout, J.R. Carruthers, P.W. Betteridge,
CRYSTALS Issue 10, Chemical Crystallography Laboratory,
University of Oxford, 1996.
.