Synthesis and use of mono- or bisxylyl linked bis(benzimidazolium) bromides as carbene precursors for C-C bond formation reactions

Article abstract of DOI:10.1016/j.jorganchem.2007.11.015

Two benzimidazolium moieties linked by one or two xylyls (m- and p-) have been synthesized, characterized and then they were used for Heck coupling reactions as in situ formed catalysts. Mono bridged salts are more efficient as compared to bisbridged salts. In addition, mono bridged salts were converted to Rh-NHC complexes which were tested as catalysts for the arylation of aldehydes.

Full text of DOI:10.1016/j.jorganchem.2007.11.015

Available online at www.sciencedirect.com
Journal of Organometallic Chemistry 693 (2008) 425–434
www.elsevier.com/locate/jorganchem
Synthesis and use of mono- or bisxylyl linked
bis(benzimidazolium) bromides as carbene precursors
for C–C bond formation reactions
a
a
b
a,
a
¨
*
Hayati Turkmen , Serpil Denizaltı , Ismail Ozdemir , Engin C¸ etinkaya , Bekir C¸ etinkaya
¨
a Department of Chemistry, Ege University, 35100 Bornova-Izmir, Turkey
b Department of Chemistry, Ino¨nu¨ University, 44069 Malatya, Turkey
Received 23 October 2007; received in revised form 7 November 2007; accepted 8 November 2007
Available online 17 November 2007
Abstract
Two benzimidazolium moieties linked by one or two xylyls (m- and p-) have been synthesized, characterized and then they
were used for Heck coupling reactions as in situ formed catalysts. Mono bridged salts are more efficient as compared to bisbridged
salts. In addition, mono bridged salts were converted to Rh–NHC complexes which were tested as catalysts for the arylation of
aldehydes.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Bridged bisbenzimidazolium salts; Catalytic activities; C–C coupling; Rhodium complexes
1. Introduction
simple benzyl substituted ones in C–C bond formation
reactions [5]. In addition, the aryl part of such NHC
ligands attached to the Ru atom (II) are prone to displace
the other arene groups to form an intramolecular arene
(III) [6].
Recent studies have shown that N-heterocyclic carbenes
(NHC’s) are important ligands in metal catalyzed reactions
and the electronic and steric effects of the NHC have a
great influence on the performance of the reaction which
occurs at the metal center [1]. Thus, a number of new
NHC ligands are reported every year. The main body of
information has been accumulated on imidazol-2-ylidene
based NHC’s, whereas their corresponding benzannulated
counterpart are relatively unexplored [2]. As a matter of
fact, benzimidazol-2-ylidenes have structures reminiscent
of imidazol-2-ylidenes, but spectroscopic properties and
reactivity which are close to saturated imidazol-2-ylidenes
[3,4].
Rn
Rn
Rn
N
N
N
MLn
Ru
Ru
-arene
N
N
N
Cl
Cl
Cl
Cl
R'
R'
R'
III
II
I
The transition metal complexes of NHC ligands bearing
alkylated benzyl substituents on the N atom(s) of hetero
rings (I) are found to be more efficient catalysts than the
Therefore, the main objective of this study is to investi-
gate the influence of polymethylated benzyls in the form of
m- and o-xylyls in bimetallic systems bearing benzimidazole
framework. The bisbridged salts are known as cyclo-
phanes, and many related cyclophanes have been studied
by Baker et al. [7] and others [8].
*
Corresponding author. Tel.: +90 2323881092; fax: +90 2323881036.
E-mail address: engin.cetinkaya@ege.edu.tr (E. C¸ etinkaya).
0022-328X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.11.015

426
H. Tu¨rkmen et al. / Journal of Organometallic Chemistry 693 (2008) 425–434
2. Results and discussion
The IR data for benzimidazolium salts (1–2; 10–20)
clearly indicate the presence of the –C@N– group with a
t(C@N) vibration between 1558 and 1562 cmꢀ1 [9]
(Scheme 2).
2.1. Preparation of the 3,30- and 1,10,3,30-bridged
bibenzimidazolium precursors
These benzimidazolium salts have been characterized by
1
As mentioned in the introduction, the main aim of this
study was the attachment of sterically bulky m- or p-xylyl
groups between two benzimidazoles via the N atom(s).
The salts of general structure 1/10, 2/20, 5/50, 6/60, and
7/70 were synthesized according to Scheme 1. The introduc-
tion of the xylyl substituents into the benzimidazole system
was achieved by direct alkylation in toluene. The resulting
1,10-bridged bibenzimidazoles (3 and 4) can be alkylated to
give 1/10 and 2/20, respectively. The salts with two bridges
(5/50 and 7/70) are also easily accessible and can be obtained
by the usual quaternization of 1,10-bridged bibenzimidaz-
oles. In the case of 6/60 the cross quaternization method
was employed. There was no significant difference in total
yield in connection with the method.
1H and 13C NMR spectroscopy. H NMR chemical shifts
were consistent with the proposed structures; the reso-
nances for C2-hydrogens were observed as sharp singlets
between 9.51 and 10.86 ppm. 13C NMR of these salts
showed the C2 carbon at 140.4–142.2 ppm.
2.2. Synthesis of di-bridged bibenzimidazolium salts, II
(5–70)
The di-bridged benzimidazoles were synthesized by N-
alkylation of mono-bridged (5,6-dimethyl)benzimidazole
with the corresponding m- or p-dibromides in toluene at
reflux. These salts were purified by recrystallization from
methanol.
Br
Br
A
B
Y
Y
N
N
Y
Y
Y
Y
N
N
Y
Y
2Br -
+
2Br -
+
+
+
N
N
R
N
N
R
Br
Br
R
R
Y = H, 2 ; Me, 2'
Y = H, 1; Me, 1'
R-Br
R-Br
Y
Y
N
Y
Y
Y
Y
N
N
N
N
Y
Y
Y
N
N
N
N
A
B
N
H
Y
Y = H, Me
Y = H, 4; Me, 4'
Y = H, 3; Me, 3'
A
B
A
B
Y
Y
Y
N
N
Y
Y
Y
N
Y
Y
N
Y
Y
N
N
2Br -
2Br -
2Br -
+
+
+
+
+
+
N
N
Y
Y
N
N
N
N
Y = H, 6; Me, 6'
Y = H, 5; Me, 5'
Y = H, 7; Me, 7'
R -CH2CH2OCH3 -CH2C6H2(CH3)3-2,4,6 -CH2C6H(CH3)4-2,3,5,6 -CH2C6(CH3)5
c
a
d
b
Scheme 1. Alkylation and quaternization of benzimidazoles with A, B or R–Br.

H. Tu¨rkmen et al. / Journal of Organometallic Chemistry 693 (2008) 425–434
427
N
+
N
N
R
N
N
[Rh(OMe)COD]2
Br-
Br-
+
N
R
Br Rh
Rh Br
N
R
N
R
8
2
Scheme 2.
The IR data for symmetrical di-bridged benzimidazoles
(5,50,7,70) clearly indicate the presence of the –C@N–
group with a t(C@N) vibration between 1546 and
We noted that the NHC precursors bearing methoxyethyl
groups (1a, 10a, 2a, 20a) were the most effective of the salts
examined. We expected that activities of these salts would
increase in the following order: pentamethylbenzyl (i)
(1d, 10d, 2d, 20d) > tetramethylbenzyl (ii) (1c, 10c, 2c,
20c) > trimethylbenzyl substituent (iii) (1b, 10b, 2b, 20b).
However, the catalytic activity increases in the sequence
i > iii > ii, indicating the influence of the p-substituent. In
addition, benzimidazolium salts bearing methyl groups on
the 5,6-positions of the benzene ring have also shown better
catalytic activity than nonsubstituted counterparts. These
observations are consistent with the previous reports [1c,10].
1573 cmꢀ1
.
The 1H NMR spectrum of the metacyclophanes dis-
played the methyl protons as an 18 proton singlet at about
d = 1.54; 2.43 ppm. The N-methylene protons appeared as
doublets at about d = 5.49; 5.80 ppm. The C2–H signals
were observed at approximately d = 7.20 ppm. The 13C
NMR showed the C2 carbon at 140.9 ppm.
1
The H NMR spectrum of the paracyclophanes showed
the methyl protons as a singlet at 2.10 ppm. The benzylic
protons appeared as a singlet at 5.73–5.81 ppm. The reso-
nances for the C2–hydrogens were observed as singlets
between 6.22 and 7.23 ppm. The 13C NMR of paracyclo-
phanes showed the C2 carbon at 136.7, 137.9 ppm.
2.4. Synthesis of rhodium–carbene complexes and their
catalytic activity for arylation of aldehydes
1
The H and 13C NMR spectra of the unsymmetrical di-
Rhodium–carbene complexes and their catalytic activity
have been studied by various researchers [11,12]. In the
rhodium catalyzed addition of aryl boronic acids to alde-
hydes to give secondary alcohols, the reactions were facili-
tated by the presence of an electron-withdrawing group on
the aldehyde and an electron donating group on the aryl-
boronic acid. This observation indicates that the mecha-
nism involves a nucleophilic attack of the aryl group on
the aldehyde [13–15].
The Rh(I)–NHC complexes synthesized in this study
showed differences in their behaviour as catalyst for aryla-
tion of various aromatic aldehydes. Of the four complexes,
the complex 8a, containing 2-methoxyethyl substituent on
N1 atom, was the most efficient. As was observed in the
Heck reactions (Table 1).
bridged benzimidazoles were recorded in CD3OD. The
C2–H signals were observed at very high field (6.45–
6.67 ppm) as singlets. It is proposed that these protons
are directed towards cyclophane cavity. However, in spite
of their high field signals, these hydrogens are reactive
enough to react with basic metal salts such as [Rh(l-
OMe)(COD)]2. The benzylic protons appeared as multiplet
between 5.44 and 6.05 ppm. In the 13C NMR the C2 carbon
appeared between 141.8 and 141.9 ppm. The IR data show
the presence of the –C@N– group with a t(C@N) vibration
between 1563 and 1569 cmꢀ1
.
2.3. The Heck C–C coupling reaction
The coupling reactions of aryl halides with olefins are
usually carried out homogenously in the presence of a base
under inert atmosphere. It was noted that in situ formation
of the azolium salt led to significantly better results than
the use of the preformed complex.
We found that use of 3% Pd(OAc)2, 3% ligand and
1.5 mmol Cs2CO3 in DMA at 100 °C led to the best conver-
sion within 3 h. Under the optimised reaction conditions,
we investigated the reaction of aryl halides with n-butyl
acrylate and observed that the reactions at 100 °C gave
coupling products in good yields (62–100%). The results
obtained are summarized in Table 1.
2.4.1. General procedure for rhodium–carbene catalyzed
addition of phenylboronic acid to aldehydes
Phenylboronic acid (1.20 g, 9.8 mmol), KOBut
(4.9 mmol), the substituted aldehyde (4.9 mmol), diethyl-
eneglycol-di-n-butyl ether (0.6 mmol, internal standard)
rhodium-carbene catalyst (1 mol%) and dimethoxyethane
(15 mL) were introduced in to a two-necked 25 mL flask
and then H2O (5 mL) was added. The resulting mixture
was heated for 1 h at 80 °C under an argon atmosphere.
The conversion was monitored by gas chromatography
(Table 2).

428
H. Tu¨rkmen et al. / Journal of Organometallic Chemistry 693 (2008) 425–434
Table 1
The Heck reaction catalyzed by in situ formed (LHX + Pd(OAc)2)
O
O
COOBu
COOBu
LXH
Pd(OAc)2 /
Br
+
Cs2CO3, DMA, 100°C, 3 h
Entry
LXH
Aryl Halide
Olefin
Yield (%)
1
2
3
4
5
6
7
8
1a
1b
1c
1d
2a
2b
2c
2d
10a
10b
10c
10d
20a
20b
20c
20d
5
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoacetophenone
4-Bromoanisole
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
n-Butyl acrylate
Styrene
98
90
80
94
96
88
82
91
100
92
88
96
100
91
83
92
70
67
73
67
75
83
78
68
62
75
77
88
80
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
7
50
70
6
60
1a
1b
1c
1d
2a
2a
20a
4-Bromoanisole
4-Bromoanisole
4-Bromoanisole
4-Bromoanisole
4-Bromoacetophenone
Bromobenzene
n-Butyl acrylate
Abbreviation: LXH = benzimidazolium salts; DMA = N,N-dimethylacetamide.
Reaction conditions: 9.8 mmol of phenylboronic acid, 4.9
mmol aldehydes, 1.0 mmol% rhodium-carbene, 4.9 mmol
KOBut, dimethoxyethane (15 mL), H2O (5 mL); GC-yield
using diethyleneglycol-di-n-butyl ether as the internal stan-
dard; temperature 80 °C, 1 h.
to para bridged bisbenzimidazolium salts. In addition,
unsymmetrical cyclophanes gave better results than sym-
metrical ones.
The complexes 8 displayed differences in their behaviour
as catalysts for arylation of aldehydes.The complexes with
N-(2-methoxyethyl) substitution showed higher activities
then the complexes with N-benzyls. The general activity
trend is as follows: a > d > c > b.
3. Conclusions
In conclusion, in this study, mono- and bis-xylyl-bridged
bibenzimidazolium bromides (1, 7) were synthesized and
their in situ catalytic activities were tested for Heck reac-
tions. The Heck coupling reactions were performed
between aryl halides with n-butyl acrylate in the presence
of the salts and Pd(OAc)2 in DMA at 100 °C.
The mono-bridged bisbenzimidazolium salts bearing a
methoxyethyl substituent on the N atom (10a, 20a) are
the most effective of the salts examined. Catalytic activity
increased in the sequence: (i) > (iii) > (ii). Benzimidazoli-
um salts bearing methyl groups on the 5,6-positions have
also shown a better activity as compared to nonsubstitut-
ed ones. On the other hand, meta bridged bisbenzimidazo-
lium salts showed better catalytic activity in comparison
4. Experimental
2,4,6-Trimethylbenzyl bromide, 2,3,5,6-tetramethylben-
zyl bromide, 2,3,4,5,6-pentamethylbenzyl bromide, 1,3-bis-
(bromomethyl)-2,4,6-trimethylbenzene, 1,4-bis(brometh-
yl)-2,3,5,6-tetramethylbenzene [13], 1,3-bis(benzimidazol-
1-ylmethyl)-2,4,6-trimethylbenzene and 1,4-bis(benzimidazol-
1-ylmethyl)-2,3,5,6-tetramethylbenzene [14], 1-alkyl-5,6-
dimethylbenzimidazoles [15] were synthesized according
to the methods previously known. All reagents were pur-
chased from Merck, Fluka, Alfa Aesar and Acros Organ-
ics. Melting points were recorded with Gallenkamp
electrothermal melting point apparatus.

H. Tu¨rkmen et al. / Journal of Organometallic Chemistry 693 (2008) 425–434
429
4.1.3. 1,10-Di(methoxyethyl)-3,30-(2,4,6-trimethyl-1,3-
xylylene)bibenzimidazolium dibromide (1a)
Table 2
Rhodium–carbene catalyzed addition of phenylboronic acid to aldehydes
Yield: 90%; m.p. = 171–174 °C; t(NCN) (cmꢀ1) = 1562.
O
O
C
H
H
base,
8
B(OH)
CH
+
2
Anal. Calc. for C31H38Br2N4O2: C, 56,55; H, 5.82; N,
1
R
R
8.51. Found: C, 56.51; H, 5.81; N, 8.59%. H NMR (d,
n
n
CDCI3): 2.30, 2.48 (s, 9H, NCH2C6H(CH3)3CH2N), 3.22
(s, 6H, –OCH3), 3.80 (t, 4H, J = 1.2 Hz, NCH2CH2OCH3),
4.97 (t, 4H, J = 1.2 Hz, NCH2CH2OCH3), 5.80 (s, 4H,
NCH2C6H(CH3)3CH2N), 7,15 (s, 1H, NCH2C6H(CH3)3-
CH2N), 7.62, 7.67 (t, 4H, J = 2 Hz, C6H4), 7.83, 8.24 (d,
4H, J = 2.1 Hz, C6H4), 10.27 (s, 2H, H2). 13C NMR (d,
CDCI3): 17.6, 20.3 (-NCH2C6H(CH3)3CH2N), 46.9
(NCH2C6H1(CH3)3CH2N), 48.1, 59.2 (NCH2CH2OCH3),
71.2 (NCH2CH2OCH3), 113.9, 114.4, 126.9, 127.6, 127.7,
131.6, 132.8, 132.8, 140.5, 140.9 (NCH2C6H1(CH3)3-
CH2N,C6H4), 141.7 (C2).
Entry
8
Rn
Yield %
1
2
3
4
5
6
7
8
a
b
c
3,4,5-(OCH3)3
3,4,5-(OCH3)3
3,4,5-(OCH3)3
3,4,5-(OCH3)3
2,4,6-(CH3)3
2,4,6-(CH3)3
2,4,6-(CH3)3
2,4,6-(CH3)3
4-Cl
4-Cl
4-Cl
4-Cl
4-OCH3
93
90
90
91
97
92
94
93
96
88
94
95
96
88
91
94
d
a
b
c
d
a
b
c
9
10
11
12
13
14
15
16
4.1.4. 1,10-Di(2,4,6-trimethylbenzyl)-3,30-(2,4,6-trimethyl-
1,3-xylylene)bibenzimidazolium dibromide (1b)
d
a
b
c
4-OCH3
4-OCH3
4-OCH3
Yield: 80%; m.p. = 199–201 °C; t(NCN) (cmꢀ1) = 1560.
Anal. Calc. for C45H50Br2N4: C, 67,00; H, 6.25; N, 6.95.
Found: C, 67.11; H, 6.21; N, 6.89%. 1H NMR (d, CDCI3):
2.23, 2.25, 2.32, 2.57 (s, 18H, NCH2C6H(CH3)3CH2N,
2,4,6-CH2C6H2(CH3)3), 6.09 (s, 4H, 2,4,6-CH2C6H2-
(CH3)3), 7.26 (s, 4H, 2,4,6-CH2C6H2(CH3)3), 5.84 (s, 4H,
NCH2C6H1(CH3)3CH2N), 6,84 (s, 1H, NCH2C6H1-
(CH3)3CH2N), 6.89, 8.27 (d, 4H, J = 2.1 Hz, C6H4), 7.39,
7.62 (t, 4H, J = 2.0 Hz, C6H4), 10.86 (s, 2H, H2). 13C
NMR(d, CDCI3): 17.1, 17.3, 17.5, 17.7, 20.3, (2,4,6-
CH2C6H2(CH3)3, NCH2C6H(CH3)3CH2N), 47.3, 49.8
(2,4,6-CH2C6H2(CH3)3, NCH2C6H(CH3)3CH2N), 114.3,
114.4, 126.2, 126.9, 127.5, 127.6, 132.1, 132.0, 132.9,
133.6, 133.8, 136.9, 140.5, 140.9 (C6H4, NCH2C6H-
(CH3)3CH2N, 2,4,6-CH2C6H2(CH3)3), 141.9 (C2).
d
1H NMR and 13C NMR spectra were recorded with a
Varian AS 400 Mercury instrument. As solvents CDCl3,
CD3OD and d6-DMSO were employed. Chemical shifts
(d) are given in ppm, coupling constants (J) in Hz. FTIR
Spectra were recorded on a Perkin Elmer Spectrum 100
series.
4.1. General procedure
4.1.1. Preparation of monoxylyl linked
bis(benzimidazolium) bromides 1,2
1-Alkyl-(5,6-dimethyl)benzimidazole (2.0 mmol) was
dissolved in toluene and then 1,3-bis(bromomethyl)-2,4,6-
trimethylbenzene or 1,4-bis(bromomethyl)-2,3,5,6-tetram-
ethylbenzene (1.0 mmol) was added. The mixture was
refluxed for 4 h. The solid that separated out after cooling
was filtered off and washed with diethyl ether (5 mL). The
product was recrystallized from CH2Cl2/Et2O.
Meta bridged bibenzimidazolium salts (1a–d) were syn-
thesized by a similar method but with stirring at room tem-
perature for 24 h.
4.1.5. 1,10-Di(2,3,5,6-tetramethylbenzyl)-3,30-(2,4,6-
trimethyl-1,3-xylylene)bibenzimidazolium dibromide (1c)
Yield: 60%; m.p. = 200–202 °C; t(NCN) (cmꢀ1) = 1559.
Anal. Calc. for C47H54Br2N4: C, 67,62; H, 6.52; N, 6.71.
Found: C, 67.70; H, 6.61; N, 6.80%. 1H NMR (d, CDCI3):
2.17, 2.20 (s, 24H, 2,3,5,6-CH2C6H(CH3)4), 2.33, 2.58 (s,
9H, NCH2C6H(CH3)3CH2N), 5,86 (s, 4H, NCH2C6H-
(CH3)3CH2N), 6.15 (s, 4H, 2,3,5,6-CH2C6H(CH3)4), 7,00
(s, 1H, NCH2C6H(CH3)3CH2N), 7.32 (s, 2H, 2,3,5,6-
CH2C6H(CH3)4), 6.82, 8.22 (d, 4H, J = 2.2 Hz, C6H4),
7.34, 7.60 (m, 4H, C6H4), 10.83 (s, 2H, H2). 13C NMR
(d, CDCI3): 16.3, 20.7 (2,3,5,6-CH2C6H(CH3)4), 17.7,
20.3 (NCH2C6H(CH3)3CH2N), 47.3, 49.3 (NCH2C6H-
(CH3)3CH2N, 2,3,5,6-CH2C6H(CH3)4), 126.9, 127.5,
127.7, 128.9, 132.1, 132.9, 133.4, 134.1, 134.9, 140.5,
141.0 (C6H4, NCH2C6H(CH3)3CH2N, 2,3,5,6-CH2C6H-
(CH3)4), 141.9 (C2).
4.1.2. Preparation of bisxylyl linked bis(benzimidazolium)
bromides (5, 6, 7)
1,3-Bis(5,6-dimethyl)benzimidazol-1-ylmethyl-2,4,6-tri-
methylbenzene or 1,4-bis(5,6-dimethyl)benzimidazol-
1-ylmethyl- 2,3,5,6,-tetramethylbenzene (2.6 mmol) was
dissolved in toluene and then 1,3-bis(bromomethyl)-2,
4,6-trimethylbenzene or 1,4-bis(bromomethyl)-2,3,5,6-
tetramethylbenzene (2.6 mmol) was added. The mixture
was refluxed overnight. The solid that separated out after
cooling was filtered off and washed with diethyl ether
(5 mL).
4.1.6. 1,10-Di(2,3,4,5,6-pentamethylbenzyl)-3,30-(2,4,6-
trimethyl-1,3-xylylene)bibenzimidazolium dibromide (1d)
Yield: 65%; m.p. = 217–221 °C; t(NCN) (cmꢀ1) = 1560.
Anal. Calc. for C49H58Br2N4: C, 68,21; H, 6.78; N, 6.49.

430
H. Tu¨rkmen et al. / Journal of Organometallic Chemistry 693 (2008) 425–434
Found: C, 68.28; H, 6.81; N, 6.49%. 1H NMR (d, CDCI3):
2.05–2.54 (m, 39H, NCH2C6H(CH3)3CH2N, 2,3,4,5,6-
CH2C6(CH3)5), 6.11 (s, 2,3,4,5,6-CH2C6(CH3)5), 6.10
(s, 1H, NCH2C6H(CH3)3CH2N), 7,23 (s, 1H, NCH2C6H-
(CH3)3CH2N), 6.84, 8.18 (d, 4H, J = 2.1 Hz, C6H4), 7.33,
7.58 (t, 4H, J = 2.1 Hz, C6H4), 10,75 (s, 2H, H2). 13C
NMR(d, CDCI3): 17.6, 20.2, 20.5, 21.2 (NCH2C6H-
(CH3)3CH2N, 2,3,4,5,6-CH2C6(CH3)5), 47.3, 48.5 (–NCH2-
C6H(CH3)3CH2N, 2,3,4,5,6-CH2C6(CH3)5), 114.2, 114.5,
125.9, 126.8, 127.6, 127.7, 130.3, 131.9, 132.1, 132.9,
137.9, 139.4, 140.5, 141.1 (C6H4, NCH2C6H(CH3)3CH2N,
2,3,4,5,6-CH2C6(CH3)5), 141.97 (C2).
(CH3)3CH2N), 6.05, 6.56 (s, 4H, 2,3,5,6-CH2C6H(CH3)4),
5.74 (s, 4H, NCH2C6H(CH3)3CH2N), 7.23 (s, 1H,
NCH2C6H(CH3)3CH2N), 7.00, 7.82 (s, 4H, C6H2(CH3)2),
10.52 (s, 2H, H2). 13C NMR(d, CDCI3): 16.3, 17.6, 20.2,
20.7, 20.8, 21.1 (NCH2C6H(CH3)3CH2N, C6H2(CH3)2,
2,3,5,6-CH2C6H(CH3)4), 46.9, 48.9 (NCH2C6H(CH3)3-
CH2N, 2,3,5,6-CH2C6H(CH3)4), 113.7, 113.9, 127.1,
129.0, 130.5, 130.6, 132.7, 133.2, 134.1, 134.9, 137.5,
137.7, 140.5 (NCH2C6H(CH3)3CH2N, C6H2(CH3)2,
2,3,5,6-CH2C6H(CH3)4), 140.7 (C2).
4.1.10. 1,10-Di(2,3,4,5,6-pentamethylbenzyl)-3,30-(2,3,
5,6-tetramethyl-1,3-xylylene)5,6-dimethylbibenz-
imidazolium dibromide (10d)
4.1.7. 1,10-Di(methoxyethyl)-3,30-(2,4,6-trimethyl-1,3-
xylylene)5,6-dimethylbibenzimidazolium dibromide (10a)
Yield: 59%, m.p. = 250–253 °C t(NCN) (cmꢀ1) = 1561.
Anal. Calc. for C35H46Br2N4O2: C, 58,83; H, 6.49; N,
7.84. Found: C, 58.91; H, 6.55; N, 7.89%.1H NMR (d,
CDCI3): 2.26, 2.45, 2.49, 2.50 (s, 21H NCH2C6H-
(CH3)3CH2N, C6H2(CH3)2), 3.24 (s, 6H, –OCH3), 3.79,
4.88 (t, 8H, J = 1.2 Hz; NCH2CH2OCH3), 5.68 (s, 4H,
NCH2C6H(CH3)3CH2N), 7.16 (s, 1H, –NCH2C6H(CH3)3-
CH2N), 7.52, 7.94 (s, 4H, C6H2(CH3)2), 10.09 (s, 2H,
H2). 13C NMR (d, CDCI3): 17.6, 20.2, 20.8, 20.94
(NCH2C6H(CH3)3CH2N, C6H2(CH3)2), 46.7, (NCH2C6H-
(CH3)3CH2N), 47.7, 59.2 (–NCH2CH2OCH3), 71.2
(-OCH3), 113.5, 113.8, 127.0, 130.1, 131.2, 132.6, 137.7,
137.9, 140.4 (NCH2C6H(CH3)3CH2N, C6H2(CH3)2),
140.7 (C2).
Yield: 40%; m.p. = 197–199 °C; t(NCN) (cmꢀ1) = 1561.
Anal. Calc. for C53H66Br2N4: C, 69.27; H, 7.24; N, 6.10.
Found: C, 69.25; H, 7.25; N, 6.19%. 1H NMR (d, CDCI3):
2.19, 2.22, 2.26, 2.29, 2.31, 2.35, 2.39 (s, 51H, C6H2(CH3)2,
2,3,4,5,6-CH2C6(CH3)5), NCH2C6H(CH3)3CH2N, 5.69
(s, 4H, NCH2C6H(CH3)3CH2N), 7.09 (s, NCH2C6H-
(CH3)3CH2N), 6.93, 7.21 (s, 4H, C6H2(CH3)2), 9.56 (s,
2H, H2). 13C NMR (d, CDCI3): 15.9, 17.2, 17.3, 19.7,
20.6, 20.9 (NCH2C6H(CH3)3CH2N, C6H2(CH3)2, 2,3,4,
5,6-CH2C6(CH3)5), 47.8, 48.0 (NCH2C6H(CH3)3CH2N,
2,3,4,5,6-CH2C6(CH3)5), 113.3, 113.2, 125.2, 127.2, 130.5,
131.7, 133.6, 133.9, 134.2, 137.5, 137.7, 138.0, 138.9,
139.3 (NCH2C6H(CH3)3CH2N, 2,3,4,5,6-CH2C6(CH3)5,
C6H2(CH3)2), 140.6 (C2).
4.1.11. 1,10-Di(methoxyethyl)-3,30-(2,3,5,6-tetramethyl-1,4-
xylylene)bibenzimidazolium dibromide (2a)
4.1.8. 1,10-Di(2,4,6-trimethylbenzyl)-3,30-(2,4,6-trimethyl-
1,3-xylylene)5,6-dimethylbibenzimidazolium dibromide
(10b)
Yield: 82%; m.p. = 265–267 °C; t(NCN) (cmꢀ1) = 1560.
Anal. Calc. for C32H40Br2N4O2: C, 57.15; H, 6.00; N,
8.33. Found: C, 57.11; H, 6.05; N, 8.29%. 1H NMR
(d, CDCI3): 2.24 (s, 12H, NCH2C6(CH3)4CH2N), 3.18
(s, 6H, –OCH3), 3.72 (t, 4H, J = 1.3 Hz, NCH2CH2OCH3),
4.77 (t, 4H, J = 1.3 Hz, NCH2CH2OCH3), 5,84 (s, 4H,
NCH2C6(CH3)4CH2N), 7.72–8.21 (m, 8H, C6H4), 9,51
(s, 2H, H2). 13C NMR (d, CDCI3): 17.2 (NCH2C6-
(CH3)4CH2N), 40.9, 58.8 (NCH2CH2OCH3), 56.7
(NCH2C6(CH3)4CH2N), 70.1 (NCH2CH2OCH3), 127.4,
127.5, 130.6, 132.0, 132.3, 136.5 (C6H4, NCH2C6(CH3)4-
CH2N), 142.2 (C2).
Yield: 34%; m.p. = 172–175 °C; t(NCN) (cmꢀ1) = 1560.
Anal. Calc. for C49H58Br2N4: C, 68,21; H, 6.78; N, 6.49.
Found: C, 68.23; H, 6.72; N, 6.52%. 1H NMR (d, CDCI3):
2.15, 2.16, 2.20, 2.21, 2.38, 2.44 (s, 39H, 2,4,6-
CH2C6H2(CH3)3, C6H2(CH3)2, NCH2C6H(CH3)3CH2N),
5.94 (s, 4H, 2,4,6-CH2C6H2(CH3)3), 6.78 (s, 4H, 2,4,6-
CH2C6H2(CH3)3); 5.69 (s, 4H, NCH2C6H(CH3)3CH2N),
7.21 (s, 1H, NCH2C6H(CH3)3CH2N), 6.56, 8.00 (s, 4H,
C6H2(CH3)2), 10.58 (s, 2H, H2). 13C NMR (d, CDCI3):
17.4, 20.1, 20.4, 20.7, 21.1, 21.2 (NCH2C6H(CH3)3CH2N,
C6H2(CH3)2, 2,4,6-CH2C6H2(CH3)3), 46.9, 48.2 (NCH2-
C6H(CH3)3CH2N, 2,4,6-CH2C6H2(CH3)3), 113.8, 113.9,
126.1, 126.9, 130.2, 130.4, 130.7, 132.7, 137.8, 137.8,
137.9, 139.3, 140.1, 140.7 (NCH2C6H(CH3)3CH2N, 2,4,6-
CH2C6H2(CH3)3,C6H2(CH3)2), 140.9 (C2).
4.1.12. 1,10-Di(2,4,6-trimethylbenzyl)-3,30-(2,3,5,6-
tetramethyl-1,4-xylylene)bibenzimidazolium dibromide (2b)
Yield: 80%; m.p. = 308–310 °C; t(NCN) (cmꢀ1) = 1559.
Anal. Calc. for C46H52Br2N4: C, 67,32; H, 6.39; N, 6.83.
Found: C, 67.31; H, 6.44; N, 6.80%. 1H NMR (d, CDCI3):
1.95, 2.22, 2.34 (s, 30H, NCH2C6(CH3)4CH2N, 2,4,6-
CH2C6H2(CH3)3), 6.07 (s, 4H, 2,4,6-CH2C6H2(CH3)3),
6.83 (s, 2,4,6-CH2C6H2(CH3)3), 5,93 (s, 4H, NCH2C6-
(CH3)4CH2N), 6.87, 8.53 (d, 4H, J = 2.2 Hz, C6H4), 7.37,
7.66 (t, 4H, J = 2.0 Hz, C6H4), 10,77 (s, 2H, H2). 13C
NMR (d, CDCI3): 17.4, 20.4, 21.2 (NCH2C6(CH3)4CH2N,
2,4,6-CH2C6H2(CH3)3), 47.1, 48.2 (NCH2C6(CH3)4CH2N,
2,4,6-CH2C6H2(CH3)3), 113.9, 115.1, 125.9, 127.7, 127.7,
4.1.9. 1,10-Di(2,3,5,6-tetramethylbenzyl)-3,30-(2,4,6-
trimethyl-1,3-xylylene)5,6-dimethylbibenzimidazolium
dibromide (10c)
Yield: 46%; m.p. = 192–194 °C; t(NCN) (cmꢀ1) = 1561.
Anal. Calc. for C51H62Br2N4: C, 68.76; H, 7.01; N, 6.29.
Found: C, 68.79; H, 7.11; N, 6.23%. 1H NMR (d, CDCI3):
2.17, 2.22 (s, 24H, 2,3,5,6-CH2C6H(CH3)4), 2.20, 2.31 (s,
12H, C6H2(CH3)2), 2.41, 2.53 (s, 9H, NCH2C6H-

H. Tu¨rkmen et al. / Journal of Organometallic Chemistry 693 (2008) 425–434
431
129.5, 130.3, 131.9, 132.1, 136.7, 137.8, 139.4 (C6H4,
NCH2C6(CH3)4CH2N, 2,4,6-CH2C6H2(CH3)3), 142.1 (C2).
2.21, 2.22 (s, 18H, 2,4,6-CH2C6H2(CH3)3), 2.25, 2.50 (s,
12H, C6H2(CH3)2), 2.33 (s, 12H, NCH2C6(CH3)4CH2N),
6.84 (s, 4H, 2,4,6-CH2C6H2(CH3)3), 5,79 (s, NCH2C6-
(CH3)4CH2N), 6.61, 8.16 (s, 4H, C6H2(CH3)2); 10,60 (s,
2H, H2). 13C NMR(d, CDCI3): 17.3, 20.4, 20.7 (2,4,6-
CH2C6H2(CH3)3, NCH2C6(CH3)4CH2N), 21.1, 21.2
(C6H2(CH3)2), 47.4, 47.9 (2,4,6-CH2C6H2(CH3)3, NCH2-
C6(CH3)4CH2N), 113.7, 114.1, 126.1, 129.5, 130.2, 130.4,
130.6, 136.5, 137.7, 137.8, 137.9, 139.3 (C6H2(CH3)2,
NCH2C6(CH3)4CH2N, 2,4,6-CH2C6H2(CH3)3), 141.0 (C2).
4.1.13. 1,10-Di(2,3,5,6-tetramethylbenzyl)-3,30-(2,3,5,6-
tetramethyl-1,4-xylylene)bibenzimidazolium dibromide (2c)
Yield: 89%; m.p. = 250–251 °C (dec.); t(NCN)
(cmꢀ1) = 1561. Anal. Calc. for C48H56Br2N4: C, 67,92; H,
6.65; N, 6.60. Found: C, 67.91; H, 6.71; N, 6.59%. 1H
NMR (d, CDCI3): 2.16, 2.19, 2.32 (s, 36H, NCH2C6-
(CH3)4CH2N, 2,3,5,6-CH2C6H(CH3)4), 6.14 (s, 4H,
2,3,5,6-CH2C6H(CH3)4), 5.93 (s, 4H, NCH2C6(CH3)4-
CH2N), 6.77, 8.49 (d, 4H, J = 2.2 Hz, C6H4), 7.34, 7.65 (t,
4H, J = 2.1 Hz, C6H4), 10.78 (s, 2H, H2). 13C NMR (d,
CDCI3): 16.2, 17.4, 20.7 (–NCH2C6(CH3)4CH2N, 2,3,5,6-
CH2C6H(CH3)4), 47.9, 49.1 (NCH2C6(CH3)4CH2N,
2,3,5,6-CH2C6H(CH3)4), 114.1, 114.9, 127.6, 128.9, 129.2,
129.4, 132.0, 132.1, 133.3, 134.9, 136.6 (C6H4,
NCH2C6(CH3)4CH2N, 2,3,5,6-CH2C6H(CH3)4), 142.1 (C2).
4.1.17. 1,10-Di(2,3,5,6-tetramethylbenzyl)-3,30-(2,3,5,6-
tetramethyl-1,4-xylylene)5,6-dimethylbibenzimidazolium
dibromide (20c)
Yield: 75%; m.p. = 220–222 °C t(NCN) (cmꢀ1) = 1558.
Anal. Calc. for C52H64Br2N4: C, 69,02; H, 7.13; N, 6.19.
Found: C, 69.01; H, 7.11; N, 6.12%.1H NMR (d, CDCI3):
2.15, 2.17, 2.20, 2.33, 2.45 (s, 48H, 2,3,5,6-CH2C6H(CH3)4,
NCH2C6(CH3)4CH2N, C6H2(CH3)2), 6.07 (s, 4H, 2,3,5,6-
CH2C6H(CH3)4), 6.51 (s, 2H, 2,3,5,6-CH2C6H(CH3)4),
5,78 (s, 4H, NCH2C6(CH3)4CH2N), 6.99, 8.13 (s, 4H,
C6H2(CH3)2), 10,63 (s, 2H, H2). 13C NMR (d, CDCI3):
16.2, 17.3 (2,3,5,6-CH2C6H(CH3)4), 20.7 (NCH2C6-
(CH3)4CH2N), 20.7, 21.1 (C6H2(CH3)2), 47.4, 48.8
(2,3,5,6-CH2C6H(CH3)4, NCH2C6(CH3)4CH2N), 113.9,
129.1, 129.5, 130.5, 130.6, 133.2, 134.1, 134.8, 136.6,
137.6, 137.8 (C6H2(CH3)2, NCH2C6(CH3)4CH2N, 2,3,5,6-
CH2C6H(CH3)4), 140.9 (C2).
4.1.14. 1,10-Di(2,3,4,5,6-pentamethylbenzyl)-3,30-(2,3,5,6-
tetramethyl-1,4-xylylene) bibenzimidazolium dibromide (2d)
Yield:
77%;
m.p. = 220–221 °C
(dec.)
t(NCN)
(cmꢀ1) = 1560. Anal. Calc. for C50H60Br2N4: C, 68.49; H,
6.90; N, 6.39. Found: C, 68.54; H, 6.92; N, 6.29%. 1H
NMR (d, CDCI3): 2.16–2.33 (m, 42H, NCH2C6-
(CH3)4CH2N, 2,3,4,5,6-CH2C6(CH3)5), 6.13 (s, 4H,
2,3,4,5,6-CH2C6(CH3)5), 5.91 (s, NCH2C6(CH3)4CH2N),
6.77, 8.47 (d, 4H, J = 2.1 Hz, C6H4), 7.32, 7.63
(t, 2H,J = 1.9 Hz, C6H4), 10,78 (s, 2H, H2). 13C NMR (d,
CDCI3): 17.2, 17.4, 17.5, 20.7, (NCH2C6(CH3)4CH2N,
2,3,4,5,6-CH2C6(CH3)5), 47.9, 49.6 (NCH2C6(CH3)4CH2N,
2,3,4,5,6-CH2C6(CH3)5), 114.2, 114.9, 126.3, 127.6, 127.7,
129.5, 132.0, 132.1, 133.5, 133.7, 136.7, 136.9 (C6H4,
NCH2C6(CH3)4CH2N, 2,3,5,6-CH2C6(CH3)5), 141.9 (C2).
4.1.18. 1,10-Di(2,3,4,5,6-pentamethylbenzyl)-3,30-(2,3,5,6-
tetramethyl-1,4-xylylene)5,6-dimethylbibenzimidazolium
dibromide (20d)
Yield: 59%; m.p. = 218–220 °C; t(NCN) (cmꢀ1) = 1559.
Anal. Calc. for C45H50Br2N4: C, 67.00; H, 6.25; N, 6.95.
Found: C, 67.11; H, 6.21; N, 6.89%. 1H NMR (d, CDCI3):
2.17, 2.18, 2.22, 2.23, 2.33, 2.44 (s, 54H, NCH2C6-
(CH3)4CH2N, C6H2(CH3)2, 2,3,4,5,6-CH2C6(CH3)5), 6.53
(s, 2,3,4,5,6-CH2C6(CH3)5), 5,76 (s, 4H, NCH2C6(CH3)4-
CH2N), 6.53; 8.06 (s, 4H, C6H2(CH3)2), 10,57 (s, 2H, H2).
13C NMR (d, CDCI3): 17.1, 17.2, 17.3, 17.5 (2,3,4,
5,6-CH2C6(CH3)5, NCH2C6(CH3)4CH2N), 20.8, 21.1
(C6H2(CH3)2), 47.4, 49.3 (2,3,4,5,6-CH2C6(CH3)5, NCH2-
C6H0(CH3)4CH2N), 113.9, 114.1, 126.5, 129.5, 130.5,
130.6, 133.5, 133.6, 136.5, 136.7, 137.5, 137.7 (C6H2-
(CH3)2, NCH2C6(CH3)4CH2N, 2,3,4,5,6-CH2C6 (CH3)5),
140.9 (C2).
4.1.15. 1,10-Di(methoxyethyl)-3,30-(2,3,5,6-tetramethyl-1,4-
xylylene)5,6- dimethylbibenzimidazolium dibromide (20a)
Yield: 70%, m.p. = 268–269 °C; t(NCN) (cmꢀ1) = 1560.
Anal. Calc. for C36H48Br2N4O2: C, 59,34; H, 6.64; N,
7.69. Found: C, 59.31; H, 6.61; N, 7.77%. 1H NMR
(d, CDCI3): 2.28 (s, 12H, NCH2C6(CH3)4CH2N), 2.43,
2.50 (s, 12H, C6H2(CH3)2); 3.26 (s, 6H, –OCH3), 3.79,
4.84 (t, 4H, J = 1.2 Hz, CH2CH2OCH3), 5,71 (s, 4H,
NCH2C6(CH3)4CH2N), 7.56, 8.05 (s, 4H, C6H2(CH3)2),
10.02 (s, 2H, H2). 13C NMR (d, CDCI3): 17.3 (NCH2C6-
(CH3)4CH2N),
20.9,
20.96
(C6H2(CH3)2),
47.2
(NCH2C6(CH3)4CH2N), 47.7, 59.3 (NCH2CH2OCH3),
71.8 (OCH3), 113.6, 113.9, 129.4, 130.1, 131.3, 136.5,
137.9, 138.0 (C6H2(CH3)2, NCH2C6(CH3)4CH2N), 140.4
(C2).
4.1.19. 1,10-(2,4,6-Trimethylbenzyl-1,3-xylylene)-3,30-(2,4,
6- trimethyl-1,3-xylylene)bibenzimidazolium dibromide (5)
Yield: 65%; m.p. = 294–295 °C (dec.) t(NCN) (cmꢀ1) =
1553. Anal. Calc. for C36H38Br2N4: C, 62.98; H, 5.58; N,
8.16. Found: C, 63.01; H, 5.61; N, 8.09%.1H NMR (d,
DMSO): 1.59, 2.43 (s, 18H, NCH2C6H(CH3)3CH2N),
5.56; 5.80 (d, 8H, J = 3.7 Hz, NCH2C6H(CH3)3CH2N),
7.78 (s, 2H, NCH2C6H(CH3)3CH2N), 7.80–8.30 (m, 8H,
C6H4), 7,22 (s, 2H, H2). 13C NMR (d, DMSO): 15.6, 20.6
(NCH2C6H(CH3)3CH2N), 46.3 (NCH2C6H(CH3)3CH2N);
4.1.16. 1,10-Di(2,4,6-trimethylbenzyl)-3,30-(2,3,5,6-
tetramethyl-1,4-xylylene)5, 6-dimethylbibenzimidazolium
dibromide (20b)
Yield: 57%; m.p. = 226–228 °C; t(NCN) (cmꢀ1) = 1559.
Anal. Calc. for C50H60Br2N4: C, 68.49; H, 6.90; N, 6.39.
Found: C, 68.45; H, 6.82; N, 6.42%. 1H NMR (d, CDCI3):

432
H. Tu¨rkmen et al. / Journal of Organometallic Chemistry 693 (2008) 425–434
114.7, 127.9, 128.1 132.5, 133.0, 138.5, 138.7 (C6H4,
NCH2C6H(CH3)3CH2N), 140.9 (C2).
7.84. Found: C, 63.80; H, 5.91; N, 7.89 %.1H NMR (d,
DMSO): 2.10 (s, 24H, NCH2C6(CH3)4CH2N), 5.81 (s,
8H, NCH2C6(CH3)4CH2N), 7.90–8.37 (m, 8H, C6H4),
7,23 (s, 2H, H2). 13C NMR (d, DMSO): 16.8 (NCH2C6-
(CH3)4CH2N), 46.8 (NCH2C6(CH3)4CH2N), 114.9, 128.2,
130.9, 132.9, 136.4 (C6H4,NCH2C6(CH3)4CH2N), 136.7
(C2).
4.1.20. 1,10-(2,4,6-Trimethylbenzyl-1,3-xylylene)-3,30-
(2,4,6-trimethyl-1,3-xylylene)5,6-dimethyl-
bibenzimidazolium dibromide (50)
Yield: 60%; m.p. = 295 °C (dec.) t(NCN) (cmꢀ1) = 1573.
Anal. Calc. for C40H46Br2N4: C, 64,69; H, 6.24; N, 7.54.
Found: C, 64.71; H, 6.21; N, 6.58%. 1H NMR (d, DMSO):
1.54, 2.41 (s, 18H, NCH2C6H(CH3)3CH2N), 3.31 (s, 12H,
C6H2(CH3)2), 5.49; 5.72 (d, 8H, J = 3.7 Hz, NCH2C6H-
(CH3)3CH2N), 7.62 (s, 2H, NCH2C6H(CH3)3CH2N), 8.08
(s, 4H, C6H2(CH3)2), 7.20 (s, 2H, H2). 13C NMR
(d, DMSO): 15.9, 20.7 (NCH2C6H(CH3)3CH2N), 20.9
(C6H2(CH3)2), 46.2 (NCH2C6H(CH3)3CH2N), 114.2,
128.3, 131.0, 137.7, 138.4 (C6H2(CH3)2, NCH2C6H(CH3)3-
CH2N), 140.8 (C2).
4.1.24. 1,10-(2,3,5,6-Tetramethylbenzyl-1,4-xylylene)-3,30-
(2,3,5,6-tetramethyl-1,4-xylylene)5,6-
dimethylbibenzimidazolium dibromide (70)
Yield: 66%; m.p. = 329 (dec.); t(NCN) (cmꢀ1) = 1546.
Anal. Calc. for C42H50Br2N4: C, 65,46; H, 6.54; N, 7.27.
Found: C, 65.48; H, 6.51; N, 6.29 %. 1H NMR (d, DMSO):
2.07 (s, 24H, NCH2C6(CH3)4CH2N), 2.53 (s, 12H,
C6H2(CH3)2), 5.73 (s, NCH2C6(CH3)4CH2N), 6,22 (s, 2H,
H2), 8.14 (s, 4H, C6H2(CH3)2). 13C NMR (d, DMSO):
16.7 (NCH2C6H(CH3)4CH2N), 20.9 (C6H2(CH3)2), 46.6
(NCH2C6(CH3)4CH2N), 114.4, 131.0, 131.3, 135.2, 136.3
(C6H2(CH3)2, NCH2C6(CH3)4CH2N), 137.9 (C2).
4.1.21. 1,10-(2,4,6-Trimethylbenzyl-1,3-xylylene)-3,30-(2,3,
5,6-tetramethyl-1,4-xylylene)bibenzimidazolium dibromide (6)
Yield: 66%; m.p. = 291 °C (dec.) t(NCN) (cmꢀ1) = 1563.
Anal. Calc. for C37H40Br2N4: C, 63,44; H, 5.76; N, 8.00.
Found: C, 63.41; H, 5.82; N, 8.09%. 1H NMR (d, CD3OD):
2.15; 2.23 (s, 9H, NCH2C6H(CH3)3CH2N), 2.31 (s, 12H,
NCH2C6(CH3)4CH2N), 5.61–6.05 (m, 8H, NCH2C6H-
(CH3)3CH2N, NCH2C6(CH3)4CH2N), 7.29 (s, 1H,
NCH2C6H(CH3)3CH2N), 7.89–8.35 (m, 8H, C6H4), 6,67
(s, 2H, H2). 13C NMR (d, CD3OD): 14.6, 15.6, 18.6
(NCH2C6H(CH3)3CH2N, NCH2C6(CH3)4CH2N), 45.7,
46.3 (NCH2C6H(CH3)3CH2N, NCH2C6(CH3)4CH2N),
113.8, 113.9, 127.9, 128.1, 128.1, 131.2, 132.5, 132.7,
132.8 (C6H4,NCH2C6H(CH3)3CH2N, NCH2C6(CH3)4-
CH2N), 141.9 (C2).
4.1.25. General procedure for the preparation of [RhBr(g4-
COD)(NHC)] (8)
Complex 2 (0.32 mmol) and [Rh(OMe)COD]2 (0.32
mmol) were added in a SCHLENK tube. The mixture stirred
in toluene (8 mL) and refluxed overnight. The product
was filtered off and the filtrate was concentrated under vac-
uum, then crystallized from CH2Cl2/EtOH.
4.1.26. [Di(cyclopentadiene){1,10-di(2-methoxyethyll)-
3,30-2,3,5,6-tetramethyl-1,4-xylylene bibenzimidazole-2,20-
diylidene}]dirhodium(I) dibromide (8a)
Yield: 72%; m.p. = 290–291 °C. Anal. Calc. for
C48H62Rh2Br2N4: C, 52,76; H, 5.72; N, 5.13. Found: C,
1
4.1.22. 1,10-(2,4,6-Trimethylbenzyl-1,3-xylylene)-3,30-
(2,3,5,6-tetramethyl-1,4-xylylene)5,6-dimethyl-
bibenzimidazolium dibromide (60)
52.51; H, 5.91; N, 4.99 %. H NMR (CDCl3): 1.89–1.99
(m, 8H, COD–CH2), 2.24 (s, 12H, NCH2C6(CH3)4CH2N),
2.34–2.48 (m, 8H, COD-CH2), 3.34 (s, 6H, –OCH3), 3.41
(s, 2H, COD–CH@CH), 3.55 (s, 2H, COD–CH@CH),
4.01, 4.85 (m, 4H, NCH2CH2OCH3), 5.21 (s, 4H, COD–
CH@CH), 5.92, 6.48 (d,J = 3.7 Hz, 4H, NCH2C6(CH3)4-
CH2N), 6.10, 6.78, 7.03, 7.38 (m, 8H, C6H4). 13C NMR
(CDCl3, d, ppm): 17.9 (NCH2C6(CH3)4CH2N), 28.8, 29.7,
32.7, 33.8 (COD-CH2), 46.7 (NCH2CH2OCH3), 52.0
(NCH2C6(CH3)4CH2N), 59.8 (NCH2CH2OCH3), 70.2 (d,
J = 14.5 Hz, COD–CH@CH), 70.4 (d, J = 13.7 Hz,
COD–CH@CH), 72.5 (NCH2CH2OCH3), 99.6; 99.9 (d,
J = 6.1 Hz, COD–CH@CH), 110.6, 112.0, 123.2, 124.3,
131.9, 134.3, 135.1, 136.9 (C6H4, NCH2C6(CH3)4CH2N),
198.6 (d, J = 50.3 Hz, Rh–C).
Yield: 47%; m.p. = 327–330 °C (dec.) t(NCN) (cmꢀ1) =
1569. Anal. Calc. for C41H48Br2N4: C, 65,08; H, 6.39; N,
7.40. Found: C, 65.11; H, 6.33; N, 7.28%. 1H NMR
(d, CD3OD): 2.29 (s, 12H, NCH2C6(CH3)4CH2N), 2.17,
2.22 (s, 9H, NCH2C6H(CH3)3CH2N), 2.57 (s, 4H, C6H2-
(CH3)2), 5.44–5.97 (m, 8H, NCH2C6(CH3)4CH2N,
NCH2C6H(CH3)3CH2N), 7.27 (s, 1H, NCH2C6H(CH3)3-
CH2N), 8.07, 8.10 (s, 4H, C6H2(CH3)2), 6,45 (s, 2H, H2).
13C NMR(d, CD3OD): 14.6, 15.5, 18.6, 19.6 (NCH2-
C6H(CH3)3CH2N, NCH2C6(CH3)4CH2N, C6H2(CH3)2),
45.6, 46.2 (NCH2C6H(CH3)3CH2N, NCH2C6(CH3)4CH2-
N), 113.3, 127.7, 131.2, 131.3, 131.4, 132.4, 135.2, 135.9,
136.5, 138.7, 138.7, 138.9 (C6H2(CH3)2, NCH2C6H-
(CH3)3CH2N, NCH2C6(CH3)4CH2N), 141.8 (C2).
4.1.27. [Di(cyclopentadiene){1,10-Di(2,4,6-trimethyl-
benzyl)-3,30-2,3,5,6-tetramethyl-1,4-xylylenebibenz-
4.1.23. 1,10-(2,3,5,6-Tetramethylbenzyl-1,4-xylylene)-3,30-
(2,3,5, 6-tetramethyl-1,4-xylylene) bibenzimidazolium
dibromide (7)
Yield: 70%; m.p. = 348–350 °C (dec.) t(NCN) (cmꢀ1) =
1551. Anal. Calc. for C38H42Br2N4: C, 63,87; H, 5.92; N,
imidazole-2,20-diylidene}]dirhodium(I) dibromide (8b)
Yield: 75%; m.p. = 308–309 °C. Anal. Calc. for C62H74-
Rh2Br2N4: C, 60.01; H, 6.01; 4.52. Found: C, 60.11; H,
6.13; N, 4.43%. 1H NMR (CDCl3): 1.97–2.08 (m, 8H,
COD–CH2), 2.33 (s, 30H, NCH2C6(CH3)4CH2N,

H. Tu¨rkmen et al. / Journal of Organometallic Chemistry 693 (2008) 425–434
433
NCH2C6H2(CH3)3), 2.38–2.55 (m, 8H, COD–CH2), 3.56 (s,
Acknowledgement
2H, COD–CH@CH), 3.62 (s, 2H, COD–CH@CH), 5.28 (s,
4H, COD–CH@CH), 5.91 (d, 2H, J = 3.7 Hz,
NCH2C6(CH3)4CH2N), 6.01, 6.03 (s, 4H, NCH2C6-
(CH3)4CH2N), 6.54 (s, 2H, NCH2C6H2(CH3)3), 6.71–6.78
(m, 6H, NCH2C6H2(CH3)3, C6H4), 6.18, 6.28 (m, 4H,
C6H4), 6.92 (s, 4H, NCH2C6H2(CH3)3). 13C NMR (CDCl3,
d, ppm): 17.9, 21.2, 22.5 (NCH2C6H(CH3)3, NCH2-
C6(CH3)4CH2N), 28.9, 29.5, 32.7, 33.4 (COD–CH2), 50.4
(NCH2C6H(CH3)3), 52.0 (NCH2C6(CH3)4CH2N), 70.2 (d,
J = 14.5 Hz, COD–CH@CH), 70.4 (d, J = 13.7 Hz,
COD–CH@CH), 99.6; 99.9 (d, J = 6.1 Hz, COD–CH@
CH), 110.9, 122.0, 122.2, 128.3, 129.9, 132.3, 135.5, 135.9,
137.7, 138.5, 138.6 (C6H4, NCH2C6(CH3)4CH2N,
NCH2C6H2(CH3)3), 198.6 (d, J = 50.3 Hz, Rh–C).
Financial support from Ege University (Project 05
FEN-020) is gratefully acknowledged.
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