L. Zhang et al. / Journal of Molecular Catalysis A: Chemical 256 (2006) 171–177
173
ture, the stirrer was turn on, and the reaction time was accounted.
4.1. Structures of complexes
The conversion of benzene hydrogenation was analyzed by GC-
9790 with FID detector (detecting temperature of 250 ◦C) and
PEG-20 M supelco column (30 m × 0.25 mm, 0.25 m film) at
55 ◦C
Solid complexes 1, 2, 4 and 5 were stable in air, but their
solutions were sensitive to air. After the solution was exposed
to air for a few minutes, its color would change from yel-
1
lowish brown to green. Two doublets in 31P { H} NMR of
3. Preparations of ruthenium complex 1, 2, 4, and 5
complex 1 and 4 indicated that the coordination environments
of the two phosphorus atoms in BISBI were different because of
the diastereoisomer of the backbone of biphenyl in coordinated
BISBI. After one tetrafluoroborate group exchanged one chlo-
and 23.47 to 15.55 and 25.00 ppm, respectively. The chemical
shift 5.31 ppm of the protons on the coordinated phenyl ring
in 1H NMR spectrum was in agreement with result reported in
literature [18].
3.1. [RuCl (η6-C6H6)(BISBI)]Cl (1)
A mixture of [RuCl2(6-C6H6)]x (0.100 g, 0.40 mmol) and
BISBI (0.220 g, 0.40 mmol) in 50 ml methanol was stirred at
room temperature for 20 h. The solid substances were slowly
dissolved and the color of solution changed to yellowish brown
with small amount of white precipitate. At the end of reaction,
the solution was filtered to remove the white precipitate and fol-
lowed by solvent removal under vacuum to give 0.295 g brown
A singlet at 20.73 ppm in 31P { H} NMR of complex 2 sug-
1
gested that the chemical environments of two phosphorus atoms
were equivalent. The complex 5 was formed by one tetrafluo-
roborate substituting one chlorine anion in complex 2 and its
31P NMR spectrum shifted to 22.44 from 20.73 ppm without
substitution. 1H NMR spectrum of complex 5 showed that pro-
tons of methylene of BDPX appeared as a singlet at 3.50 ppm
and the protons on coordinated phenyl ring also appeared as a
singlet at 5.67 ppm. According to the results of NMR spectra
and elemental analysis of complex 4 and 5, they were mononu-
clear complexes in which each ruthenium atom was coordi-
Because complex 1 and 2 were the similar with complexes
by elemental analysis. The proposal structures were shown in
and 5 further confirmed the results from NMR and elemen-
tal analysis. Their crystal data were listed in Table 1 and their
structures of the single crystal X-ray diffraction were shown
in Figs. 1 and 2, respectively. The selected bond lengths and
bond angles of complexes 4 and 5 were listed in Table 2.
1
solid. Yield: 92%. 31P { H} NMR: δ(ppm), 14.29 (d), 23.47 (d).
3.2. [RuCl(η6-C6H6)(BDPX)]Cl (2)
Complex 2 was prepared by the similar procedure as complex
1
1. Yield: 87%. 31P { H} NMR: δ(ppm) 20.73 (s).
3.3. RuCl (η6-C6H6) (BISBI)] BF4 (4)
A suspension of [RuCl(6-C6H6)(BISBI)]Cl (0.160 g,
0.20 mmol) and AgBF4 (0.040 g, 0.20 mmol) in the mixture sol-
vent of CH2Cl2 (7 ml) and methanol (10 ml) was stirred for 2 h
at room temperature, and then formed AgCl was filtered off.
The filtrate was evaporated to about 6 ml under vacuum and was
put in refrigerator over night to give a lot of brown red crystals.
The crystals were filtered, washed for two times with methanol,
and then dried in vacuum. 0.106 g brown crystals were obtained.
Yield: 62.3%. Calc. for C46H42BCl5F4P2Ru: C, 54.04; H, 4.11;
found: C, 54.36; H, 4.12. 31P { H} NMR: δ(ppm) 15.55 (d),
1
25.00 (d), Jpp = 54.2 Hz. 1H NMR: δ(ppm) 3.48 (s, 4H), 5.31 (s,
The bond length of Ru–P (1) 2.3670 A was slightly differ-
˚
˚
6H), 6.80–7.70 (m, 28H).
ent from that of Ru(1)–P(2) 2.3772 A in complex 4, and both
˚
3.4. [RuCl (η6-C6H6) (BDPX)] BF4 (5)
2.3764 A in complex 5, Ru(1)–P(1) 2.329 A, Ru(1)–P(2)
˚
˚
6
˚
2.336 A in complex [( -p-cymene)(dppe)RuCl]BF4 [7] and
6
˚
˚
Complex 5 was prepared by using complex 2 as starting mate-
rials, and the same procedure as complex 4. Yield: 82%. Calc.
for C39H36BCl3F4P2Ru: C, 54.39; H, 4.18; found: C, 54.49; H,
Ru(1)–P(1) 2.316 A, Ru(1)–P(2) 2.309 A in complex [( -p-
cymene)(dppm) RuCl]BF4 [7]. They were very close to the
bond length in some binuclear complexes, such as Ru(1)–P(1)
1
4.10. 31P { H} NMR: δ(ppm) 22.44 (s). 1H NMR: δ(ppm) 3.45
2.345 A, Ru(1)–P(2) 2.357 A in complex 3, and Ru(1)–P(1)
˚
˚
6
˚
˚
(s, 4H), 5.67 (s, 6H), 7.00–8.00 (m, 24H)
2.3471 A, Ru(1)–P(2) 2.3767 A in complex [Ru2Cl2( -
C6H6)2(-BDNA)2](BF4)2 [17]. The bond length of Ru–C
˚
˚
4. Results and discussion
(average 2.248 A) in complex 5 was slightly shorter than 2.258 A
in complex 4, all Ru–C in complexes 4 and 5 were longer than
˚
˚
In order to compare the activities of mononuclear com-
plexes bearing diphosphine ligands with dinuclear complexes,
mononuclear complexes 1, 2, 4 and 5 in which one ruthenium
atom was coordinated by a BISBI or a BDPX and the dinu-
clear complexes 3 and 6 in which two ruthenium atoms shared
a BDNA were prepared. The reaction equations and structures
of all Ru–6-C6H6-diphosphine complexes were illustrated in
Scheme 1.
Ru(1)–C (average 2.188 A) and Ru(2)–C (average 2.175 A) in
complex 6. The bond angle of P(1)–Ru(1)–P(2) in complex 4
was 98.62◦. It was larger than 95.94◦ in complex 5, obviously
larger than 91.4◦ in [(6-C6H6)RuCl(BINAP)]+ [18] and much
larger than 83.03◦ in [(6-p-cymene)(dppe)RuCl]BF4 or 71.29◦
in [(6-p-cymene)(dppm)RuCl]BF4 because the size of chelat-
ing ring and the backbone of ligand increased in the order of
dppm < dppe < BDPX < BISBI.