Article
Organometallics, Vol. 29, No. 21, 2010 5287
The reaction mixture was heated under reflux for 3 h. Com-
pound 3 precipitated as a tan solid and was isolated by filtration.
It could be used without further purification for subsequent
reactions. Yield: 3.2 g (18.2 mmol, 90.5%). 1H NMR (400 MHz,
DMSO-d6): δ 8.10 (s, 1H, H1), 7.42 (s, 2H, H4 and H7), 6.62
(s, 1H, OH), 5.52 (d, 2H, H10), 2.31 (s, 3H, H8), 2.30 (s, 3H, H9).
13C{1H} NMR (100 MHz, DMSO-d6): δ 142.8 (s, C1), 142.4
(s, C3), 131.9 (s, C2), 130.8 (s, C5), 129.9 (s, C6), 119.3 (s, C4),
110.8 (s, C7), 67.1 (C10), 20.0 (C8) 19.8 (C9). MS (ESI HRMS)
m/z (%): 147.0914 (100) [3 - CH2OH þ H]þ (calcd for [M -
CH2OH þ H]þ 147.0917). Anal. Calcd: C, 68.15; H, 6.86; N,
15.90. Found: C, 67.93; H, 6.77; N, 15.73.
Table 1. Crystallographic Data for the
Complexes [6] THF 0.5CH2Cl2 and [7]
3
[6] THF 0.5CH2Cl2
3
parameter
[7]
3
3
formula
cryst size [mm]
C
37.5H47N2Cl2OPRu C32H36N2ClPRu
0.06 ꢀ 0.05 ꢀ 0.03
606.12
0.07 ꢀ 0.07 ꢀ 0.03
Mr
a [A]
744.71
˚
28.9982(11)
28.9982(11)
16.8529(8)
90.0
14.4177(11)
11.8422(9)
16.6450(10)
90.0
˚
b [A]
˚
c [A]
R [deg]
β [deg]
γ [deg]
90.0
90.0
90.0
90.0
3
Compound 4 HCl. A sample of 0.91 g (5.2 mmol, 6.2 mmol) of
˚
3
V [A ]
Z
space group
14171.5(10)
16
I41/a
2841.9(4)
4
Pna21
3 was dissolved in dichloromethane (20 mL). To this was added
3.25 mL of SOCl2 (44.8 mmol). The reaction mixture was stirred
at ambient temperature for 1 day. The initially soluble reactants
started to precipitate during the first 30 min of stirring. However
the stirring was continued for one day to complete the reaction.
The solvent was removed with a cannula, and the residue remain-
ing was washed twice with dichloromethane (20 mL each). The
F
calcd [g cm-3
]
1.396
0.670
1.440
6.033
μ [mm-1
]
2θ range [deg]
data collected
no. unique data, Rint
3.8-55.0
41 892
8134, 0.060
9.2-139.8
15 744
5277, 0.162
2920
0.0635
no. obsd data [I g 2σ(I)] 5921
white solid obtained was dried in vacuo to give compound 4 HCl
3
R (obsd data)
wR (all data)
no. of variables
0.0467
0.1246
403
as a hygroscopic white solid. Yield: 0.93 g (4.04 mmol, 79.2%).
1H NMR (400 MHz, DMSO-d6): δ 9.64 (s, 1H, H1), 7.71 (s, 1H,
H7), 7.67 (s, 1H, H4), 6.37 (s, 2H, H10), 2.52 (s, 3H, H8), 2.47
(s, 3H, H9). 13C{1H} NMR (100 MHz, DMSO-d6): δ 143.4
(s, C1), 132.4 (s, C6), 131.5 (s, C5), 129.0 (s, C3), 128.7 (s, C2),
116.3 (s, C4), 114.5 (s, C7), 53.9 (s, C10), 20.7 (s, C8), 20.5 (s, C9).
MS (ESI HRMS) m/z (%): 195.0698 (100) [4 þ H]þ (calcd for
[4 þ H]þ 195.0689). The downfield shift of the resonance for H1
0.1435
341
(m, 1H, H11), 2.29 (s, 3H, H9), 2.28 (s, 3H, H8), 1.39 (s, 15H,
Cp-CH3). 13C{1H} NMR (100 MHz, C6D6): δ 203.4 (d, 2JCP
=
1
26.0 Hz, C1), 142.1 (m, JCP = 34.4 Hz, Ar-Cipso), 139.2 (m,
2
1JCP = 30.5 Hz, Ar-Cipso), 135.2 (m, JCP = 10.0 Hz, Ar-
2
ortho), 135.0 (s, C2), 134.8 (s, C3), 132.8 (m, JCP = 9.5 Hz,
C
indicates the formation of the benzimidazolium salt 4 HCl. The
Ar-Cortho), 130.3 (s, C6), 129.8 (s, C5), 129.0 (s, Ar-Cpara),
128.9 (s, Ar-Cpara), 128.5 (m, 3JCP=10.0 Hz, Ar-Cmeta), 127.7
(m, 3JCP =8.7 Hz, Ar-Cmeta), 111.2 (s, C4), 109.1 (s, C7), 89.0
(d, 2JCp=2.2 Hz, Cp-C), 43.3 (s, C10), 29.7 (m, 1JCP=29.7 Hz,
C11), 20.2(s, C9), 20.1 (s, C8), 10.1 (s, Cp-CH3). 31P{1H} NMR
(162 MHz, C6D6): δ 40.9. MS (ESI HRMS) m/z: 595.1812 [6 -
Cl]þ (calcd for [6 - Cl]þ 595.1816). Anal. Calcd: C, 62.80; H,
6.23; N, 4.44. Found: C, 58.30; H, 5.97; N, 4.13. Complex [6] was
crystallized as red crystals with the composition [6] THF
3
resonance for the N-H proton, however, could not be observed
in DMSO over an extended period of time and is therefore not
listed here.
Compound 5. A sample of compound 4 HCl (0.40 g, 1.73 mmol)
3
was dissolved in THF (20 mL). To this was added a solution of
diphenylphosphine (318 mg, 1.73 mmol) and KO-tBu(485mg, 4.33
mmol) in the THF (20 mL). The reaction mixture was stirred at
ambient temperature for 3 h. The initially deep red color of the mix-
ture turned pale over the reaction time. Subsequently, all solvents
were removed under high vacuum. The oily solid obtained was then
dissolved in ethyl acetate (20 mL). Reduction of the volume of the
ethyl acetate solution to 2 mL and addition of n-pentane (20 mL)
led to precipitation of a white solid, which was isolated by filtration.
The solid was then washed with pentane and dried in vacuo to give
analytically pure 5 as a colorless hygroscopic solid. Yield: 175 mg
(0.523 mmol, 30.2%). 1H NMR (400 MHz, C6D6): δ 7.83 (m, 1H,
H4), 7.27 (s, 1H, H1), 7.14 (d, 4H, Ar-Hortho), 7.08 (s, 1H, H7),
3
3
0.5CH2Cl2 by cooling of a THF/CH2Cl2 (1:1, v/v) solution of
the complex to -30 °C for 1 day.
Complex [7]. A mixture of the ligand precursor 5 (76.0 mg,
0.22 mmol) and [RuCp*(μ3-Cl)]4 (60.1 mg, 0.06 mmol) was
heated in THF (10 mL) under reflux for 6 h under an argon
atmosphere. Subsequently, the solvent was removed in vacuo
and the solid residue was washed with n-pentane several times to
obtain the raw complex [7] as a red to orange powder, which was
very sensitive to air and moisture. The red-orange solid was
dissolved in THF, and this solution was cooled to -30 °C to
obtain single crystals of [7] suitable for X-ray analysis. Yield:
96 mg (0.16 mmol, 71%). 1H NMR (400 MHz, THF-d8): δ 10.91
(s, 1H, NH), 7.93 (m, 2H, Ar-Hortho), 7.44 (m, 2H, Ar-Hmeta),
7.43 (m, 1H, Ar-Hpara), 7.15 (m, 3H, H4 and Ar-Hmeta), 7.14
(m, 1H, Ar-Hpara), 6.90 (s, 1H, H7), 6.88 (m, 2H, Ar-Hortho),
4.72 (m, 1H, H10), 4.06 (m, 1H, H10), 2.24 (s, 3H, H9), 2.18 (s,
3H, H8), 1.56 (s, 15H, Cp-CH3). 13C{1H} NMR (100 MHz,
THF-d8): δ 207.5 (d, 2JCP =14.3 Hz, C1), 143.4 (d, 1JCP =36.7
7.02 (s, 2H, Ar-Hpara), 6.98 (m, 4H, Ar-Hmeta), 4.22 (d, 2JHP
=
6.1 Hz, 2H, H10) 2.22 (s, 3H, H9), 2.17 (s, 3H, H8). 13C{1H} NMR
3
(100 MHz, C6D6): δ 143.9 (s, C3), 142.4 (d, JCP = 2.3 Hz, C1),
=
136.2 (d, 1JCP=14.5 Hz, Ar-Cipso), 133.3 (s, C2), 133.2 (d, 2JCP
18.8 Hz, Ar-Cortho), 131.6 (s, C6), 130.9 (s, C5), 129.5 (s,
3
Ar-Cpara), 129.0 (d, JCP = 6.8 Hz, Ar-Cmeta), 121.4 (s, C4),
110.9 (d, 4JCP=3.9 Hz, C7), 45.6 (d, 1JCP=16.9 Hz, C10), 20.6 (s,
C9), 20.2 (s, C8). 31P{1H} NMR (162 MHz, C6D6): δ -20.5. MS
(EI, 50 eV) m/z (%): 344 (100) 5þ.
2
Complex [6]. A mixture of compound 2 (86.0 mg, 0.24 mmol)
and the ruthenium tetramer [RuCp*(μ3-Cl)]4 (60.1 mg, 0.06 mmol)
in THF (10 mL) was heated under reflux for 10 h. The initially
brown, soluble starting materials turned into an orange suspen-
sion within the first 5 min. Within the next 3 h again a clear
orange solution was obtained. At the end of the reaction the
solvent was removed under reduced pressure. The residual solid
was washed with n-pentane, leaving complex [6] as a reddish
powder, which was dried in vacuo. Yield: 102 mg (0.14 mmol,
56%). 1H NMR (400 MHz, THF-d8): δ 10.60 (s, 1H, NH), 7.59
(d, 2H, Ar-Hortho), 7.40 (m, 2H, Ar-Hortho), 7.31 (m, 2H,
Ar-Hmeta), 7.27 (m, 1H, Ar-Hpara), 7.23 (m, 1H, H4), 7.10
(m, 1H, Ar-Hpara), 7.09 (m, 2H, Ar-Hmeta), 7.07 (s, 1H, H7),
4.74 (m, 1H, H10), 4.07 (m, 1H, H10), 2.75 (m, 1H, H11), 2.28
Hz, Ar-Cipso), 136.8 (d, JCP = 12.2 Hz, Ar-Cor1tho), 135.8 (s,
C3), 132.9 (d, JCP = 9.2 Hz, C2), 132.5 (m, JCP = 38.6,
3
Ar-Cipso), 131.1 (d, 2JCP=9.7, Ar-Cortho), 130.7 (s, Ar-Cpara),
=
130.3 (s, C6), 129.8 (s, C5), 129.1 (s, Ar-Cpara), 128.6 (d, 3JCP
9.0 Hz, 2 ꢀ Ar-Cmeta), 111.5 (s, C4), 110.4 (s, C7), 89.9 (d,
1
2JCP = 2.9 Hz, Cp-C), 50.4 (d, JCP = 29.8 Hz, C10), 20.2 (s,
C9), 20.0 (s, C8), 10.5 (s, Cp-CH3). 31P{1H} NMR (162 MHz,
THF-d8): δ 79.3. HRMS (ESI) m/z: 597.1609 (calcd for [7- Cl þ
O] 597.1612). Satisfactory microanalytical data could not be
obtained in multiple runs.
Titration of [6] with DMPU. Complex [6] (10 mg, 0.016 mmol)
was placed in an NMR tube. To this was added the appropriate
amount of DMPU (DMPU=1,3-dimethyltetrahydropyrimidin-
2(1H)-one) dissolved in 0.3 mL of C6D6.