10
K. Mashima et al. / Journal of Organometallic Chemistry 557 (1998) 3–12
4.3. Preparation of Cp*TaCl2(p4-C14H10) (12)
solution changing from light green to dark green. While
the reaction mixture was stirred for 10 h at 50°C, the
color of the solution changed from dark green to brown
purple. All volatiles were removed under reduced pres-
sure to give a residue, from which the product was
extracted with hexane (170 ml). Recrystallization from
toluene (4.0 ml) at −20°C afforded 16 as black purple
A suspension of anthracenemagnesium (1.08 mmol)
in THF (4.5 ml) was added dropwise over a 15 min
period to Cp*TaCl4 (0.551 g, 1.20 mmol) dissolved in
THF (50 ml) at −78°C. The color of the solution
changed from orange to dark red. The reaction mixture
was stirred for 2 h and then allowed to warm to room
temperature. The color of the solution changed from
dark red to dark-green. After being evaporated to
dryness, the product was extracted with toluene (10 ml)
and hexane (500 ml). Recrystallization from toluene (8
ml) at −20°C afforded 2 as dark-green crystals in 34%
yield, m.p. 188–190°C (dec). 1H NMR (270 MHz,
C6D6, 30°C) l 7.63(m, 2H, 5,8-H of anthracene),
7.36(m, 2H, 2,3-H of anthracene), 7.27(m, 2H, 6,7-H of
anthracene), 6.88(s, 2H, 9,10-H of anthracene), 2.74(m,
2H, 1,4-H of anthracene), 1.71(s, 15H, C5Me5): 13C
1
crystals in 42% yield; mp 162–163°C (dec). H NMR
(400 MHz, C6D6, 30°C): l −0.36 (2H, m, ꢁCH2 anti),
1.48 (15H, s, C5Me5), 3.05 (2H, m, ꢁCH2 syn), 4.51
(2H, br, ꢁCH–), 5.16 (8H, s, COT). 13C NMR (100
1
MHz, C6D6, 30°C): l 10.8 (q, JCH=127 Hz, C5Me5),
1
1
53.6 (t, JCH=149 Hz, ꢁCH2), 103.6 (d, JCH=154 Hz,
COT), 110.2 (s, C5Me5), 126.4 (d, 1JCH=163 Hz,
ꢁCH–). Anal. Calcd for C22H29Nb: C, 68.39; H, 7.57.
Found: C, 67.71; H, 7.54.
4.6. Preparation of Nb(PhCꢀCPh)Cp*(cot) (20)
1
NMR(100 MHz, C6D6, 30°C) l 127.1(d, JC–H=158
Hz, 5,8-H of anthracene), 125.3 (d, 1JC–H=175 Hz,
Complex 16 (2.9 mg, 0.008 mmol) was dissolved in
0.3 ml of C6D6 in a 5 mm NMR tube. To the dark-pur-
ple solution was added PhCꢀCPh (1.4 mg, 0.008 mmol)
in 0.3 ml of C6D6 at 25°C. After the NMR tube was
sealed and placed for 5 h in an oil bath heated at 50°C,
1
2,3-H of anthracene), 125.3 (s, C5Me5), 124.7 (d, JC–
H=159 Hz, 6,7-H of anthracene), 121.8(d, 1JC–H=158
Hz, 9,10-H of anthracene), 78.6(d, 1JC–H=153 Hz,
1
1,4-H of anthracene), 11.2 (q, JC–H=128 Hz, C5Me5):
1
Anal. Calcd for C24H25Cl2Ta: C, 50.99; H, 4.46. Found:
C, 50.91; H, 4.41.
the H NMR was measured. Peaks arising from free
butadiene (l 6.3 and 5.1, m, C4H6) were observed
1
together with ones of 20. H NMR (270 MHz, C6D6,
4.4. Preparation of Cp*Ta(p4-C14H10)(CH2Ph)2 (14)
30°C): l 1.43 (15H, s, C5Me5), 4.75 (8H, s, COT), 7.11
(2H, overlapped by phenyl signals of free PhCꢀCPh
3
A solution of PhCH2MgCl (0.68 mmol) in THF (1.0
ml) was added dropwise over a 20 min period to
Cp*TaCl2(p4-C14H10) (12) (0.167 g, 0.30 mmol) dis-
solved in THF (40 ml) at −78°C. The reaction mixture
was stirred for 30 min and then allowed to warm to
room temperature. After being evaporated to dryness,
the product was extracted with hexane (180 ml). Re-
crystallization from toluene (2 ml) and hexane (4 ml) at
0°C afforded 14 as dark-green crystals in 57% yield,
peaks), 7.41 (4H, t, JHH=7.6 Hz, m-Ph), 7.97 (4H, d,
3JHH=6.9 Hz, o-Ph).
4.7. Crystallographic Data Collections and Structure
Determination of 1, 14, and 16
The crystals of 14 suitable for X-ray diffraction
sealed in glass capillaries under argon atmosphere, were
mounted on a Rigaku AFC-7R four-circle diffractome-
ter for data collection using Mo–Kh radiation. Three
standard reflections were chosen and monitored every
150 reflections. Measured non-equivalent reflections
with I\3.0|(I) were used for the structure determina-
tion. Empirical absorption correction was carried out
based on an azimuthal scan.
The systematic absences of h0l (l odd) and 0k0 (k
odd) indicate the space group to be P21/c. The struc-
ture was solved by the direct method (SHELXS86) [48]
and expanded using standard Fourier maps. In the final
refinement cycle (full-matrix), hydrogen atom coordi-
nates were included at idealized positions, and the
hydrogen atoms were not refined but were given the
same temperature factor as that of the carbon atom to
which they were bonded. All calculations were per-
formed using the TEXSAN crystallographic software
package. For 428 variable parameters and 5210 ob-
served reflections with I\3.0|(I), R and Rw values
1
m.p. 140–144°C. H NMR (270 MHz, C6D6, 30°C) l
7.57 (m, 2H, 5,8-H of anthracene), 7.34 (t, 4H, m-H of
Ph), 7.23 (m, 2H, 2,3-H of anthracene), 6.97 (t, 2H,
p-H of Ph), 6.90 (m, 2H, 6,7-H of anthracene), 6.77(d,
4H, o-H of Ph), 6.72 (s, 2H, 9,10-H of anthracene),
2.12(m, 2H, 1,4-H of anthracene), 1.59 (s, 15H, C5Me5),
2
1.46 and 0.13 (AB quartet, JH–H=11.1 Hz, 4H, CH2):
Anal. Calcd for C38H39Ta: C, 67.45; H, 5.81. Found: C,
67.36; H, 5.73.
4.5. Preparation of Cp*Nb(p4-buta-1,3-diene)(cot) (16)
To a solution of NbCl2Cp*(p4-buta-1,3-diene) (0.271
g, 0.768 mmol) in THF (50 ml) cooled at −78°C was
added cyclooctatetraene (1.2 equiv, 0.88 mmol) in THF
(0.40 M, 2.20 ml) and CH3MgI (2.3 equiv, 1.74 mmol)
in ether (0.62 M, 2.80 ml) via syringe. The reaction
mixture was allowed to warm to 20°C, the color of the
Mashima, Kazushi
