Ru Hydrotris(pyrazolyl)borate Dihydrogen Complexes
Organometallics, Vol. 16, No. 1, 1997 43
3
for a while, 10 mL of degassed hexane was layered onto the
solution. The mixture was allowed to stand for 1 day.
Diffusion of hexane into the dichloromethane solution resulted
in formation of yellow crystals. The crystals were collected
by filtration, washed with hexane under nitrogen, and dried
6.94-7.30 (m, 30H, PC
H (pz)] (pz ) pyrazolyl group trans to H
6
H
5
); 7.63 [d, 2H, H (pz′)]; 7.71 [d, 1H,
3
2
O, pz′ ) pyrazolyl
group trans to PPh ; all coupling constants for pyrazolyl proton
3
3
1
1
resonance were about 2 Hz).
P{ H} NMR (121.49 MHz,
CDCl , 25 °C): δ 40.4 (s).
3
1
under vacuum overnight. Yield: 24 mg (80%). H NMR (400
[
Ru (HB(p z)
0.57 mmol) of RuCl(HB(pz)
of LiBF were added to a two-necked round bottom flask fitted
with a condenser. The setup was flushed with nitrogen for
5 min. Distilled acetonitrile (50 mL) was added through a
3
)(P P h
3
)(CH
3
CN)
2
]BF
4
, 6. Samples of 0.50 g
MHz, CD
2
Cl
2
2
, 25 °C): δ -8.20 [br, ω1/2 ) 27 Hz, 2H, Ru-(H )];
(
3
)(PPh
3 2
) and 0.054 g (0.57 mmol)
4
4
5
5
6
.75 [t, 1H, H (pz); 5.92 [t, 2H, H (pz′)]; 6.23 [d, 1H, H (pz);
4
5
6 5
.54 [d, 2H, H (pz′)]; 7.06-7.55 (m, 30H, PC H ); 7.80 [d, 2H,
3
3
H (pz′)]; 7.96 [d, 1H, H (pz)] (pz ) pyrazolyl group trans to
η -H
1
2
2
, pz′ ) pyrazolyl group trans to PPh
3
; all coupling
cannular under nitrogen. The mixture was refluxed for 4 h,
and the resulting pale yellow solution, which was suspended
with white fine solids, was filtered through Celite under
nitrogen. The pale yellow filtrate solution was concentrated
to a few milliliters, and diethyl ether was added to obtain an
off-white fine solid, which was filtered out and washed with
ether. Finally the solid was vacuum-dried at room tempera-
ture for 8 h. Yield: 0.26 g (52%). Anal. Calcd for C31
4 8
N PRu: C, 49.96; H, 4.19; N, 15.03. Found: C, 49.73; H,
.00; N, 14.73. IR (KBr, cm ): ν(B-H) 2488 (br, med), ν-
CtN) 2281 (w), ν(B-F) 1084 (br, vs). H NMR (400 MHz,
constants for pyrazolyl proton resonance were about 2 Hz).
3
1
P NMR (161.70 MHz, CDCl
temperature T measurements on the η -H
out by the inversion-recovery method using standard 180°-
τ-90° pulse sequences. T (400 MHz, CD Cl , ms): 32 (297
K), 27 (283 K), 25 (273 K), 23 (263 K), 22 (253 K), 21 (243 K),
1 (233 K), 23 (223 K), 30 (203 K). T (min) (21 ms at 240 K
and 400 MHz) was obtained from the “V”-shaped ln T vs
3
, 25 °C): δ 43.4 (s). Variable-
2
1
2
signal were carried
1
2
2
2
1
31 2
H B -
1
F
4
(
4
5
1
000/T plot.
Ru (HB(p z)
of 3 was not isolated but was prepared and observed in an
NMR tube. Thus a sample of 10 mg of RuH(HB(pz) )(PPh
-
1
[
3
)(P P h
3
)
2
(HD)]BF
4
, 3-d
1
. The HD isotopomer
1
4
CDCl
6
3
3
, 25 °C): δ 2.23 (s, 6H, CH CN), 5.83 [t, 2H, H (pz)],
3
3
)
2
4
5
.22 [t, 1H, H (pz′)], 6.61 [d, 2H, H (pz)], 7.04-7.35 (m, 15H,
was loaded into a 5 mm NMR tube which was then capped
with a rubber septum. The tube was evacuated and filled with
nitrogen, and this procedure was repeated three times. Dichlo-
5
3
PC
6
H
5
), 7.58 [d, 1H, H (pz′)], 7.64 [d, 2H, H (pz)], 8.04 [d, 1H,
CN; pz′ ) pyrazolyl
; all coupling constants for pyrazolyl proton
3
H (pz′)] (pz ) pyrazolyl group trans to CH
3
group trans to PPh
resonance were about 2 Hz).
CDCl , 25 °C): δ 45.6 (s).
Ru Cl(HB(p z) )(P P h )(CH
(0.57 mmol) of RuCl(HB(pz)
3
romethane-d
followed by addition of 6 µL of DBF
adding 0.1 mL of D O into 0.4 mL of 56% HBF
2
(0.5 mL) was syringed in to dissolve the sample,
solution (prepared by
‚Et O) through
31
1
P{ H} NMR (121.49 MHz,
4
3
2
4
2
1
3
3
3
CN), 7. A sample of 0.50 g
)(PPh was added to a two-
a microsyringe. The H NMR spectrum of the resulting
2
3
3 2
)
solution was then taken. The η -HD signal (δ -8,25 (tt),
1
2
necked round bottom flask fitted with a condenser, and the
system was evacuated and flushed with nitrogen. A degassed
solution mixture of tetrahydrofuran and acetonitrile (30 mL)
in 9:1 ratio was added through a syringe. The solution was
stirred under nitrogen at 60 °C for 6 h. At the end of the
reaction, the solution was concentrated to a few milliliters and
a yellow solid precipitated out. The solid was filtered out and
washed with diethyl ether and then hexane. Finally, it was
collected and dried under vacuum at room temperature.
J (HD) ) 32.0 Hz, J (HP) ) 6.5 Hz) was observed after nulling
2
the η -H
2
peak at δ -8.20 using the inversion-recovery method
with a delay time of 20 ms.
Ru (HB(p z) )(P P h (CH
HB(pz) )(PPh (0.50 g, 0.59 mmol) was added to a two-necked
[
3
3
)
2
3 4
CN)]BF , 4. A sample of RuH-
(
3
3 2
)
round bottom flask which was evacuated and flushed with
nitrogen. Degassed dichloromethane (100 mL) was added to
the flask through a cannular, and degassed acetonitrile (0.5
mL) was added using a syringe and needle. The mixture was
stirred for 15 min. One equivalent (20 µl) of tetrafluoroboric
Yield: 0.26 g (67%). Anal. Calcd for C29
7
H28BClN PRu: C,
5
3.35; H, 4.32; N, 15.02. Found: C, 53.80; H, 4.65; N, 14.92.
acid in ethereal solution (HBF
4
2
‚Et O, 56%) was added through
-
1
1
IR (KBr, cm ): ν(CtN) 2278 (w); ν(B-H) 2474 (br, med). H
NMR (300 MHz, CDCl , 25 °C): δ 2.10 (s, 3H, CH CN), 5.75
t, 1H), 5.84 (t, 1H), 6.22 (t, 1H), 6.62 (d, 1H), 6.94 (d, 1H),
H ), 7.63 (d, 1H + 1H), 7.65 (d, 1H),
6 5
.07 (d, 1H), (all coupling constants for the pyrazolyl proton
a syringe. The mixture was stirred for 0.5 h. At the end of
the reaction, the solution was concentrated to a few milliliters
and a creamy-white solid precipitated out. The solid was
filtered out and washed with diethyl ether. Finally, it was
collected and dried under vacuum at room temperature.
3
3
(
7
.23-7.41 (m, 15H, PC
8
3
1
1
resonance were about 2 Hz).
P{ H} NMR (121.49 MHz,
, 25 °C): δ 51.7 (s). FAB-MS (nba matrix) (m/z): 653,
Yield: 0.47 g (83%). Anal. Calcd for C47
43 2 4 7 2
H B F N P Ru: C,
CDCl
[M] ; 612, [M - CH
3
5
8.41; H, 4.48; N, 10.14. Found: C, 58.72; H, 4.35; N, 10.30.
+
+
+
-
1
1
3
CN] ; 576, [M - CH CN - Cl] ; 363,
3
IR (KBr, cm ): ν(CtN) 2276 (w); ν(B-H) 2487 (br, med). H
NMR (400 MHz, CD Cl , 25 °C): δ 2.17 (s, 3H, CH CN); 5.49
t, 1H, H (pz)]; 5.76 [t, 2H, H (pz′)]; 6.14 [d, 1H, H (pz)]; 6.32
+
[RuPPh
3
] .
2
2
3
4
4
5
[
[
(
Ru H(HB(p z)
pear-shaped flask was loaded with RuCl(HB(pz)
CN) (0.30 g, 0.46 mmol) and NaBH (0.16 g, 4.2 mmol). The
3
)(P P h
3
)(CH
3
CN), 8. A 50 mL two-necked
5
3
d, 2H, H (pz′)]; 6.83-7.26 (m, 30H, PC
6
H
5
); 7.64 [d, 2H, H -
pz′); 7.74 [d, 1H, H (pz)] (pz ) pyrazolyl group trans to CH
; all coupling constants
3
)(PPh )(CH -
3
3
3
3
-
4
CN, pz′ ) pyrazolyl group trans to PPh
for pyrazolyl proton resonance were about 2 Hz).
NMR (161.1 MHz, CDCl , 25 °C): δ 40.1 (s).
Ru (HB(p z) )(P P h (H O)]BF , 5. A sample of 0.50 g
0.59 mmol) of RuH(HB(pz) )(PPh was added to a 50 mL
3
flask was degassed and then filled with nitrogen, and this
procedure was repeated three times. Freshly distilled anhy-
drous THF (20 mL) was added to the flask. The reaction
mixture was stirred and refluxed under nitrogen for 14 h. At
the end of the reaction, the mixture was filtered. The filtrate
solvent was removed, and a yellow powder was obtained.
Anhydrous diethyl ether (10 mL) was added to dissolve the
solid. Any insoluble matter was filtered off. The filtrate
solution was then concentrated to ca. 1-2 mL, and dry pentane
was added to give an air-sensitive yellow solid. The solid was
vacuum dried and stored under nitrogen. Yield: 0.26 g (52%).
3
1
1
P{ H}
3
[
3
3
)
2
2
4
(
3
3 2
)
two-necked pear-shaped flask under nitrogen. Degassed
dichloromethane (2 mL) was syringed into the flask, followed
by addition of slightly over 1 equiv of tetrafluoroboric acid in
ethereal solution (20 µL, HBF
was stirred at room temperature for 5 min, 1 mL of H
4
‚Et
2
O, 56%). After the mixture
O was
2
added to the mixture, and the resulting solution was stirred
for a further 10 min. Addition of degassed hexane (30 mL)
led to the precipitation of a yellowish brown solid. This was
then filtered out and dried under vacuum. Yield: 0.42 g (75%).
7
Anal. Calcd for C29H29BN PRu: C, 56.32; H, 4.73; N, 15.85.
Found: C, 56.70; H, 4.90; N, 15.66. IR (KBr, cm ): ν(B-H)
-
1
1
2461 (br, med), ν(CtN) 2258 (w), ν(Ru-H) 1890 (w). H NMR
2 2
Cl
, 25 °C): δ -13.91 (d, 1H, 2J (HP) ) 28.0
Anal. Calcd for C45
H
42
B
2
F
4
N
6
OP
2
Ru: C, 57.29; H, 4.49; N,
(400 MHz, CD
Hz, Ru-H), 1.69 (s, 3H, CH
6.14 (t, 1H), 6.50 (d, 1H), 7.11 (d, 1H), 7.12-7.28 (m, 15H,
PC6H ), 7.53 (d, 1H), 7.60 (d, 1H), 7.75 (d, 1H); (all coupling
1
8
.91. Found: C, 57.95; H, 4.60; N, 8.82. H NMR (400 MHz,
3
CN), 5.60 (t, 1H), 5.93 (t, 1H),
4
CDCl
3
, 25 °C): δ 2.54 (br, s, 2H, H
2
O); 5.39 [t, 1H, H (pz)];
5
4
5
5
.71 [d, 1H, H (pz)]; 5.79 [t, 2H, H (pz′)]; 6.54 [d, 2H, H (pz′)];
5
Chan, Wai-Chung
