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N.J. Sweeney et al. / Journal of Organometallic Chemistry 690 (2005) 4537–4544
the synthesis of 3b it was used the pure reagent. THF and
diethyl ether were dried over Na and benzophenone. For
the synthesis of 3c, CH2Cl2 was dried over calcium hy-
dride. Solvents were freshly distilled and collected under
an atmosphere of argon prior to use. Manipulations of
air and moisture sensitive compounds were done using
standard Schlenk techniques, under an argon atmo-
sphere. NMR spectra were measured on either a Varian
300 or a 500-MHz spectrometer. Chemical shifts are re-
ported in ppm and are referenced to TMS. IR spectra
were recorded on a Perkin Elmer Paragon 1000 FT-IR
Spectrometer employing a KBr disk. UV–Vis spectra
were recorded on a Unicam UV4 Spectrometer. A single
crystal of titanocene 3b suitable for X-ray diffraction
experiments was grown by the diffusion of pentane into
a saturated solution of 3b in dichloromethane at room
temperature. A single crystal of 3c was grown by slow
evaporation from a saturated chloroform solution of
3a, to which was added an ethereal solution of HCl. X-
ray diffraction data for the two compounds was collected
on a BRUKER Smart Apex diffractometer at 100 K. A
semi-empirical absorption correction on the raw data
was performed using the program SADABS [25]. The
crystal structures were then solved by direct methods
(SHELXS-NT97) [26] and refined by full-matrix least
squares methods against F2. Further details about the
data collection are listed in Table. 1, as well as reliability
factors. Further details are available free of charge from
the Cambridge structural database under the CCDC
Nos. 264345 and 264344 for 3b and 3c, respectively.
The yellow lithium cyclopentadienide intermediate 2a
(1.65 g, 7.9 mmol, 67.5% yield) was dissolved in THF
(80 ml), followed by drop wise addition of TiCl4 (4.0
ml of a 1.0 M solution in toluene) at 0 ꢁC. The resultant
red solution was refluxed for 16 h during which time it
darkened in colour. The solution was then cooled and
the solvent was removed under reduced pressure. The
remaining residue was extracted with dichloromethane
(75 ml) and filtered through celite to remove the LiCl.
The dark red filtrate was filtered twice more by gravity
filtration. The solvent was removed under reduced pres-
sure to yield a very dark red solid, which was dried in
vacuo (1.25 g, 2.0 mmol, 50.1% yield).
1H NMR (d ppm CDCl3, 300 MHz): 7.10 [C6H4N-
(CH3)2, J 6.6 Hz, 4H, d]; 6.72 [C6H4N(CH3)2, J 6.0
Hz, 4H, d]; 6.33–6.31 [C5H4, 8H, m]; 3.99 [Cp–CH2–
C6H4N(CH3)2, 4H, s]; 2.95 [C6H4N(CH3)2, 12H, s].
13C NMR (d ppm CDCl3, 125 MHz), 149.4, 138.4,
130.0, 129.8, 122.2, 116.8, 113.3 [C5H4 and C6H4]; 41.1
[C6H4N(CH3)2]; 36.2 [Cp–CH2–C6H4N(CH3)2].
IR absorptions (cmꢀ1 KBr): 3113, 3085, 2890, 2803,
1611, 1521, 1488, 1440, 1354, 821, 805, 752, 677.
Anal. Calc. for C28H32N2Cl2Ti: Theory: C, 65.26; H,
6.26; N, 5.43. Found: C, 65.60; H, 6.38; N, 5.31%.
UV–Vis (CH2Cl2): k 265 nm (e 39,000), k 315 nm (e
11,000), kmax 400 nm (e 1000), kmax 540 nm (weak).
3.2. Bis-[(p-methoxybenzyl)cyclopentadienyl]titanium
(IV) dichloride, [(g5-C5H4–CH2–C6H4–O–CH3)]2-
TiCl2 (3b)
LiB(Et)3H (14.0 ml of a 1.0 M solution in THF) was
concentrated by removal of the solvent by heating it to
90 ꢁC under vacuum of 10ꢀ2 mbar for 2 h. The concen-
trated reagent was dissolved in diethyl ether (80 ml) and
to this solution was added 1b (2.27 g, 12.3 mmol) in
diethyl ether (40 ml); the solution was stirred (12 h), dur-
ing which time lithium cyclopentadienide intermediate
2b precipitated from the solution and the colour of the
solution changed from orange to yellow. 2b was allowed
to settle and was filtered to remove the filtrate. 2b was
then collected on a frit and washed with diethyl ether
(75 ml), dried briefly in vacuo and transferred to a
Schlenk flask under argon.
The white lithium cyclopentadienide intermediate 2b
(1.01 g, 5.27 mmol, 42.7% yield) was dissolved in THF
(40 ml) and it was added to a solution of TiCl4 (0.3
ml, 2.65 mmol) in THF (80 ml) at 0 ꢁC. The resultant
dark red solution was refluxed for 16 h. The solution
was then cooled and the solvent was removed under re-
duced pressure. The remaining residue was extracted
with chloroform (50 ml) and filtered through celite to re-
move the LiCl. The brown filtrate was filtered twice
more by gravity filtration. The solvent was removed un-
der reduced pressure to yield a red-brown solid, which
was dried in vacuo (0.70 g, 1.4 mmol, 54.0% yield).
3. Synthesis
6-(p-N,N-dimethylanilinyl)fulvene (1a) and 6-p-
(methoxyphenyl)fulvene (1b) were synthesised according
to the procedures used previously [21,23].
3.1. Bis-[(p-dimethylaminobenzyl)cyclopentadienyl]
titanium (IV) dichloride, [(g5-C5H4–CH2–C6H4–
N(CH3)2)]2TiCl2 (3a)
LiB(Et)3H (12.4 ml of a 1.0 M solution in THF) was
concentrated by removal of the solvent by heating it to
90 ꢁC under a vacuum of 10ꢀ2 mbar for 2 h. The con-
centrated reagent was dissolved in diethyl ether (75 ml)
and was transferred to a solution of 1a (2.30 g, 11.7
mmol) in diethyl ether (200 ml). The solution was stir-
red (12 h), during which time the lithium cyclopenta-
dienide intermediate 2a precipitated from the solution
and the colour of the solution changed from red to or-
ange. After stirring, the precipitate was allowed to set-
tle and was filtered to remove the filtrate. 2a was then
collected on a frit and washed with diethyl ether (75
ml), dried briefly in vacuo and transferred to a Schlenk
flask under argon.