An iodide/anion exchange route to benzimidazolylidene silver complexes from benzimidazolium iodide: Crystal structures of N,N′-dibutylbenzimidazolylidene silver chloride, bromide, cyanide and nitrate

Article abstract of DOI:10.1016/j.jorganchem.2007.05.019

Syntheses of N,N′-dibutylbenzimidazolylidene silver complexes having chloride, nitrate or cyanide as an anion part through an iodide/anion exchange from N,N′-dibutylbenzimidazolium iodide are described, representing a practical route to benzimidazolylidene silver complexes from readily accessible benzimidazolium iodide. The crystal structures of N,N′-dibutylbenzimidazolylidene silver chloride, bromide, cyanide and nitrate have been determined, showing a close ligand-unsupported Ag-Ag interaction in [(NHC)₂]Ag⁺[AgX₂]^- and a T shape geometry about the silver(I) cation in complexes of chloride, bromide and cyanide, but a nearly linear shape in the bis(N,N′-dibutylbenzimidazolylidene) silver complex [(NHC)₂ Ag]⁺ NO₃^- with non-coordinating nitrate anion.

Full text of DOI:10.1016/j.jorganchem.2007.05.019

Journal of Organometallic Chemistry 692 (2007) 3804–3809
www.elsevier.com/locate/jorganchem
An iodide/anion exchange route to benzimidazolylidene
silver complexes from benzimidazolium iodide: Crystal structures
of N,N0-dibutylbenzimidazolylidene silver chloride, bromide,
cyanide and nitrate
a
a
a,b,
c
Wen Huang , Ruixue Zhang , Gang Zou
*, Jie Tang a,b, Jie Sun
a
Department of Chemistry, East China Normal University, 3663 North Zhongshan Rd., Shanghai 200062, China
Laboratory for Advanced Materials, Department of Fine Chemicals, East China University of Science and Technology,
130 Meilong Rd., Shanghai 200237, China
b
c
State Key Laboratory for Organometallic Chemistry, Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Rd., Shanghai 200032, China
Received 6 January 2007; received in revised form 3 May 2007; accepted 15 May 2007
Available online 23 May 2007
Abstract
Syntheses of N,N0-dibutylbenzimidazolylidene silver complexes having chloride, nitrate or cyanide as an anion part through an
iodide/anion exchange from N,N0-dibutylbenzimidazolium iodide are described, representing a practical route to benzimidazolylidene
silver complexes from readily accessible benzimidazolium iodide. The crystal structures of N,N0-dibutylbenzimidazolylidene silver chlo-
ride, bromide, cyanide and nitrate have been determined, showing
a close ligand-unsupported Ag–Ag interaction in
[(NHC)2]Ag+[AgX2]ꢀ and a ‘‘T’’ shape geometry about the silver(I) cation in complexes of chloride, bromide and cyanide, but a nearly
linear shape in the bis(N,N0-dibutylbenzimidazolylidene) silver complex [ðNHCÞ2AgꢁþNO3ꢀ with non-coordinating nitrate anion.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Silver; N-heterocyclic carbene; Benzimidazolylidene; Anion exchange; Crystal structure
1. Introduction
dazolylidene-supported transition metal complexes have
been reported to display some properties remarkably differ-
ent from the corresponding imidazolylidene ones as both
homogeneous catalysts and materials [5–12]. Unlike the
imidazolylidenes, free benzimidazolylidenes are not stable
enough to be isolated unless their dimerization is sterically
blocked [13–16]. Therefore, benzimidazolylidene silver
halides represent a reliable and practical benzimidazolylid-
ene source in preparation of N-heterocyclic carbene transi-
tion metal complexes of benzimidazolylidenes. Although
the first benzimidazolylidene silver bromide, N,N0-diethyl-
benzimidazolylidene silver bromide, was reported in 1998
among the earliest structurally characterized N-heterocy-
clic carbene silver complexes [17], few benzimidazolylidene
silver complexes have been characterized crystallographi-
cally [1]. Herein we report the syntheses and crystal struc-
N-heterocyclic carbene silver complexes have recently
attracted many attentions owing to their structure diversity
as well as utility as carbene transfer reagents for access to a
diversity of transition metal N-heterocyclic carbene com-
plexes [1–3]. Although several sorts of N-heterocyclic carb-
enes have been reported, imidazolylidenes have dominated
the field of N-heterocyclic carbene chemistry partly due to
the wide applications of imidazolylidenes as supporting
ligands in transition metal catalysts [4]. Recently, benzimi-
*
Corresponding author. Address: Department of Chemistry, East
China Normal University, 3663 North Zhongshan Rd., Shanghai
200062, China.
E-mail address: zougang@ecust.edu.cn (G. Zou).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.05.019

W. Huang et al. / Journal of Organometallic Chemistry 692 (2007) 3804–3809
3805
tures of N,N0-dibutylbenzimidazolylidene silver complexes
of chloride, bromide, cyanide and nitrate as well as
iodide/chloride, iodide/cyanide or iodide/nitrate exchanges
in the reaction of N,N0-dibutylbenzimidazolium iodide
with silver(I) oxide in CH2Cl2, CH3CN or THF in the pres-
ence of NOꢀ3 anion, respectively.
N,N0-dibutylbenzimidazolium bromide as the carbene pre-
cursor. The observation of iodide/chloride but no bromide/
chloride exchanges had been tentatively attributed to the
poorer solubility of benzimidazolylidene silver iodide in
CH2Cl2 than its bromide and chloride analogs considering
that the largest silver dihalogen anion [AgI2]ꢀ typically
shows poor solubility in organic solvents [21]. To test this
hypothesis, the reaction of N,N0-dibutylbenzimidazolium
iodide with Ag2O was switched to polar non-chlorosol-
vents, such as CH3CN, CH3OH and THF. In the case of
acetonitrile, N,N0-dibutylbenzimidazolylidene silver cya-
nide 3 was obtained in 37% yield and no NHC silver iodide
was isolated from the reaction solution. When the reaction
was carried out in CH3OH or THF under the otherwise
identical conditions, bis(N,N0-dibutylbenzimidazolylidene)
silver nitrate 4 was obtained in about 17% yield from the
reaction solution, possibly due to the residue of NOꢀ3 in
Ag2O that was prepared from AgNO3. In deed, the yield
of nitrate 4 increased to 63% if 0.5 equiv. AgNO3 was
deliberately added to the reaction mixture (Scheme 1).
The failures in isolation of N,N0-dibutylbenzimidazoly-
lidene silver iodide by reaction of N,N0-dibutylbenzimi-
dazolium iodide with Ag2O in various solvents implied
that instability of benzimidazolylidene silver iodide is
more likely to be responsible for the iodide/anion
exchange in the formation of benzimidazolylidene silver
complexes from benzimidazolium iodide. The rationale
for the instability of benzimidazolylidene silver iodide
may lie in a confliction of the well-known strong r-donat-
ing property of both NHC carbene and iodide. The stron-
ger r-donating property of iodide anion than chloride and
bromide ones leads to an electron-richer silver species AgI
or [AgI2]ꢀ, which would be reluctant to attract another
strong r-donating NHC carbene ligand or the corre-
sponding biscarbene silver species [(NHC)2Ag]+. There-
fore, the reaction of readily available benzimidazolium
iodides with Ag2O should represent a practical route to
the benzimidazolylidene silver complexes having a non-
iodide anion part, especially when the corresponding
benzimidazolium salts are not easy to access, such as the
chloride, cyanide and nitrate.
2. Results and discussion
We previously reported a preparation of bis(N,N0-dibu-
tylbenzimidazolylidene) palladium chloride in low yield by
reaction of the corresponding benzimidazolylidene silver
bromide generated in situ with palladium chloride [18].
The low yield was obviously due to the use of benzimidaz-
olylidene silver bromide with palladium chloride, which
unavoidably led to a mixture of benzimidazolylidene palla-
dium bromide and chloride. However, the reaction of N-
butylbenzimidazole with 1-chlorobutane to prepare the
benzimidazolylidene precursor, N,N0-dibutylbenzimidazo-
lium chloride, was found to be very sluggish giving only
8% yield after heating a mixture of N-butylbenzimidazole
and 1-chlorobutane (excess) in acetonitrile at reflux for
48 h while the reactions of N-butylbenzimidazole and
1-bromobutane or 1-iodobutane completed in 6 or 2 h,
respectively, under the similar conditions. We noticed some
reports in the literature that imidazolylidene silver chlo-
rides were obtained by reaction of the corresponding imi-
dazolium iodides with Ag2O in CH2Cl2, namely, an
iodide/chloride anion exchange occurred in the formation
of imidazolylidene silver halides in chlorinated solvents
[1,19,20]. However, this iodide/chloride exchange is not
always observed and no investigation has been performed
to evaluate if the iodide/chloride exchange would represent
a synthetic route to imidazolylidene silver chlorides. When
N,N0-dibutylbenzimidazolium iodide was subjected to
Ag2O (2.0 equiv.) in CH2Cl2 at room temperature, N,N0-
dibutylbenzimidazolylidene silver chloride 1 was isolated
in 49% yield according to the elemental analyses, EI-MS
and X-ray crystal structure determination (see below)
although the ‘‘normal’’ product, N,N0-dibutylbenzimidaz-
olylidene silver bromide 2, was isolated in 76% yield using
Scheme 1. The iodide/anion exchange route to benzimidazolylidene silver complexes.

3806
W. Huang et al. / Journal of Organometallic Chemistry 692 (2007) 3804–3809
Fig. 1. ORTEP drawing (30% thermal ellipsoids) of N,N0-dibutylbenzimidazolylidene silver chloride 1.
It is not clear at present how the iodide/anion exchanges
from the solvents themselves CH2Cl2 or CH3CN by cleav-
age of C–X (X = Cl, CN) bonds [22].
exactly occurred. A possible route is formation of AgX at
first, followed by coordination of benzimidazolylidene gen-
erated in situ or from the decomposition of benzimidazoly-
lidene silver iodides. A possible source of anions Xꢀ might
be the HX residues in the solvents of CH2Cl2 and CH3CN.
However, use of CH2Cl2 and CH3CN distilled from K2CO3
as the solvents, complexes 1 and 3 were still the sole NHC
silver complexes isolated from the reaction, respectively,
indicating the anions Xꢀ should alternatively originate
ORTEP drawings of the X-ray crystal structures of the
NHC silver complexes 1, 3 and 4 are shown in Figs. 1–3,
respectively. The structure of 2 is essentially identical to
1, thus being omitted. The selected bond lengths and angles
of 1–4 are compiled in Table 1.
Fig. 3. ORTEP drawing (30% thermal ellipsoids) of bis(N,N0-dibutyl-
benzimidazolylidene) silver nitrate 4 (one of the three similar but discrete
molecules in the unit cell).
Fig. 2. ORTEP drawing (30% thermal ellipsoids) of N,N0-dibutylbenzim-
idazolylidene silver cyanide 3.

W. Huang et al. / Journal of Organometallic Chemistry 692 (2007) 3804–3809
3807
Table 1
˚
Selected bond lengths (A) and angles (ꢁ) for complexes 1–4
1
2
3
4
Ag(1)–C(1)
Ag(1)–C(16)
Ag(1)–Ag(2)
Ag(2)–X(1)
Ag(2)–X(2)
C(1)–N(1)
C(1)–N(2)
C(16)–N(3)
C(16)–N(4)
2.096(4)
2.091(4)
2.9342(7)
2.3311(14)
2.3288(13)
1.344(5)
1.342(5)
1.341(5)
1.355(5)
2.098(10)
2.105(10)
2.9516(15)
2.4271(15)
2.4280(15)
1.363(11)
1.388(11)
1.338(11)
1.355(11)
2.081(5)
2.090(5)
2.9693(9)
2.068(8)
2.096(8)
1.341(6)
1.339(6)
1.330(7)
1.359(6)
2.077(5)
2.086(5)
–
–
–
1.331(7)
1.355(7)
1.348(6)
1.354(6)
C(1)–Ag(1)–C(16)
C(1)–Ag(1)–Ag(2)
C(16)–Ag(1)–Ag(2)
X(1)–Ag(2)–Ag(1)
X(2)–Ag(2)–Ag(1)
X(1)–Ag(2)–X(2)
177.94(18)
88.32(13)
89.83(12)
93.25(4)
89.85(4)
176.89(6)
179.0(4)
91.6(4)
87.8(3)
89.63(5)
94.74(5)
175.60(7)
178.8(2)
88.97(16)
90.59(17)
88.6(2)
93.0(3)
178.3(3)
178.2(2)
–
–
–
–
–
Similar to the reported N,N0-diethylbenzimidazolylidene
silver bromide [17], complexes 1–3 crystallize in P2(1)/n
ride 2.335 A. Similarly, the Ag–Br bond lengths, 2.4271
˚
ꢀ
˚
and 2.4280 A in [AgBr2] anion of complex 2, are close
group showing
a
structure consisting of cationic
to those in N,N0-diet0hylbenzimidazolylidene silver bromide
[(NHC)2Ag]+ and anionic [AgX2]ꢀ with a close ligand-
(2.448 A) and N,N -dimethylimidazolylidene silver bro-
˚
ꢀ
˚
unsupported Ag–Ag interaction while complex 4 crystal-
mide (2.4390 A). The Ag–CN bond lengths in [Ag(CN)2]
anion of complex 3, 2.068 and 2.096 A, also fall in the
˚
ꢀ
lizes in P1 group with three similar but discrete molecules
in the unit cell showing a mononuclear ionic structure con-
sisting of a silver cation supported by two NHC ligands,
[(NHC)2Ag]+ and a nitrate anion. The geometry around
silver in complexes 1–3 is the common ‘‘T’’ shape for a
three-coordinate silver atom. The Ag–Ag bonds in com-
plexes 1–3 are nearly perpendicular (87.8–93.2ꢁ) to both
the linear NHC–Ag–NHC with C(1)–Ag(1)–C(16) bond
angles of 177.9–179.0ꢁ and the linear X–Ag–X with X(1)–
Ag(2)–X(2) bond angles of 175.6–178.3ꢁ. In complex 4,
the silver cation is linearly bonded by two NHC carbenes
with C(1)–Ag(1)–C(16) bond angle of 178.2ꢁ. The nitrate
anion does not directly interact with the silver cation,
instead, forms O–H–O hydrogen bonds with the incorpo-
rated water molecules in the crystal.
range reported in the literature for the anion, such as
˚
˚
2.06–2.10 A in TlAg(CN)2 [23], 2.052–2.062 A in
˚
(CH3CN)2LiAg(CN)2 [24] and 2.074–2.055 A in
[R3Te][Ag(CN)2] (R = CH3, Ph) [25].
3. Conclusion
In conclusion, N,N0-dibutylbenzimidazolylidene silver
complexes of chloride, cyanide and nitrate have been syn-
thesized by reaction of N,N0-dibutylbenzimidazolium
iodide with Ag2O through abstracting Clꢀ and CNꢀ anions
from solvents CH2Cl2 and CH3CN, respectively, or in the
presence of NOꢀ3 anion in reaction mixture. Crystal struc-
tures of N,N0-dibutylbenzimidazolylidene silver chloride,
bromide, cyanide and nitrate were determined, unmistak-
ably confirming the iodide/anion exchanges. The possible
rationale for the iodide/anion exchanges lies in the instabil-
ity of benzimidazolylidene silver iodides. The iodide/anion
exchange route possibly represents a practical route to pre-
pare a diversity of benzimidazolylidene silver complexes
with a non-iodide anion part from readily available benz-
imidazolium iodides and silver(I) oxide, especially when
the benzimidazolium salts are difficult to access.
The distances of Ag–Ag in complexes 1–3, 2.9342,
˚
2.9516 and 2.9693 A, respectively, are at the low end of
the known ligand-unsupported Ag–Ag interaction (2.80–
0
˚
3.30 A) [20], comparable to that in N,N -diethylbenzimi-
˚
dazolylidene silver bromide (2.954 A), but significantly
shorter than those in the imidazolylidene analogs
[Ag(NHC)2]+[AgX2]ꢀ of N,N0-dimethylimidazolylidene sil-
˚
˚
ver chloride (3.188 A) and bromide (3.2082 A). The lengths
of the coordination bonds between NHC carbene and sil-
ver ion, C(1)/C(16)–Ag(1) in complexes 1–4, are 2.077–
˚
2.105 A slightly longer than those observed in
4. Experimental
[Ag(NHC)2]+[AgBr2]ꢀ of N,N0-diethylbenzimidazolylidene
0
˚
silver bromide (2.05–2.07 A), but close to those in N,N -
dimethylimidazolylidene silver chloride (2.096 A) and bro-
mide (2.084 A) as well as the average value of 2.087 A in
the biscarbene silver cation with non-coordinating anions
4.1. General
˚
˚
˚
All manipulations were performed in air unless other-
wise indicated. All the commercially available chemicals
were used as received. N-butylbenzimidazole and N,N0-dib-
utylbenzimidazolium bromide were prepared according to
˚
ranging from 2.06 to 2.117 A [1]ꢀ. The Ag–Cl bond lengths,
˚
2.3311 and 2.3288 A in [AgCl2] anion of complex 1, are
1
close to that in N,N0-dimethylimidazolylidene silver chlo-
our previously reported procedure [18]. H NMR spectra

3808
W. Huang et al. / Journal of Organometallic Chemistry 692 (2007) 3804–3809
were recorded on a Bruker 500 spectrometer using the res-
idue of deuterated solvents as the internal standard. EI-MS
and elemental analyses were performed at the Center for
Analysis and Structure Determination of ECNU.
4.5. Synthesis of N,N0-dibutylbenzimidazolylidene silver
bromide (2)
A similar procedure to the synthesis of N,N0-dibutyl-
benzimidazolylidene silver chloride was adopted with
N,N0-dibutylbenzimidazolium bromide (0.311 g, 1.0 mmol)
to provide 2 as colorless crystals (0.318 g, 76%). m.p.: 175–
177ꢁC. Anal. Calc. for C30H44Ag2Br2N4: C, 43.09; H, 5.30;
4.2. Preparation of silver(I) oxide
To a rigorously stirred stock NaOH(aq.) solution
(1.0 M, 110 mL, 110 mmol) was added dropwise a freshly
prepared aqueous solution of AgNO3 (17 g, 100 mmol in
100 mL H2O) at room temperature. A fine brown precipi-
tate formed immediately upon addition. The precipitate
was filtered, washed with deionized water (3 · 100 mL)
and dried in suction at room temperature for 10 h. A fine
brown powder (10.6 g, 92%) was obtained and used in
the following experiments.
1
N, 6.70. Found: C, 43.57; H, 5.46; N, 6.73%. H NMR
(CDCl3,25 ꢁC), d, ppm: 7.49–7.52 (4H, m, Ar–H), 7.28–
7.47 (4H, m, Ar–H), 4.41 (8H, t, J = 7.3 Hz, N–CH2),
1.81–1.83 (8H, m, CH2), 1.31–1.43(8H, m, CH2), 0.98–
1.01(12H, t, J = 7.4 Hz, CH3). EI-MS (70 equiv., based
on Ag107): m/z (relative intensity): 416 (14%) 1/2[M]+,
337 (70%) [1/2MꢀBr]+, 309 (16%), 229 (50%) [NHCꢀ1]+,
188 (100%).
4.3. Synthesis of N,N0-dibutylbenzimidazolium iodide
4.6. Synthesis of N,N0-dibutylbenzimidazolylidene silver
cyanide (3)
To an acetonitrile (20 mL) solution of N-butylbenzimi-
dazole (1.74 g, 10 mmol) was added 4 equiv. n-Iodobutane
(7.4 g, 40 mmol) at room temperature under N2. The result-
ing mixture was refluxed for 2 h before cooling to room tem-
perature. Then toluene (20 mL) was added to the reaction
mixture to precipitate a pale yellow powder, which was sep-
arated by filtration and washed with ether (3 · 10 mL) to
provide N,N0-dibutylbenzimidazolium iodide 3.42 g,
(96%). m.p.: 107–108ꢁ C. Anal. Calc. for C15H23N2I Æ
0.5H2O: C, 49.01; H, 6.59; N, 7.62. Found: C, 48.86; H,
A similar procedure to the synthesis of N,N0-dibutyl-
benzimidazolylidene silver chloride but using CH3CN as
solvent was adopted with N,N0-dibutylbenzimidazolium
iodide (0.359 g, 1.0 mmol) to provide 3 as pale yellow crys-
tals (0.14 g, 37%). m.p.: 198–200 ꢁC. Anal. Calc. for
C32H44Ag2N6 Æ H2O: C, 51.46; H, 6.16; N, 11.26. Found :
1
C, 51.99; H, 6.07; N, 11.24% H NMR (CDCl3, 25 ꢁC),
d, ppm: 7.52–7.57 (4H, m, Ar–H), 7.45–7.49 (4H, m,
Ar–H), 4.50 (8H, t, J = 7.4 Hz, N–CH2), 1.95–2.00 (8H,
m, CH2), 1.45–1.49 (8H, m, CH2), 0.98–1.02 (12H, t,
J = 7.0 Hz, CH3). EI-MS (70 equiv., based on Ag107):
m/z (relative intensity): 363 (8%) 1/2[M]+, 337 (70%)
[1/2MꢀCN]+, 258 (20%), 230 (72%) [NHC]+, 189 (100%).
1
6.48; N, 7.52%. H NMR (CDCl3, 25 ꢁC), d, ppm: 11.2
(1H, s), 7.75–7.80 (2H, m, Ar), 7.65–7.70 (m, Ar, 2H), 4.67
(4H, t, J = 7.0 Hz, NCH2), 2.05–2.10 (4H, m, CH2), 1.45–
1.55 (4H, m, CH2), 0.95–1.05 (6H, t, J = 7.0 Hz, CH3).
4.4. Synthesis of N,N0-dibutylbenzimidazolylidene silver
chloride (1)
4.7. Synthesis of N,N0-dibutylbenzimidazolylidene silver
nitrate (4)
To a CH2Cl2 (20 mL) solution of N,N0-dibutylbenzimi-
dazolium iodide (0.358 g, 1.0 mmol) was added 2 equiv.
Ag2O (0.464 g, 2 mmol) at room temperature. A plenty of
off-white precipitate formed and the resulting mixture
was stirred in dark for 48 h. Most of the off-white precipi-
tate disappeared and the insoluble brown solid (excess
Ag2O) was filtered off with the aid of celite. The filtrate
was concentrated to about 5 mL and some hexane was
carefully added to reach a cloudy point. The resulting
cloudy solution was allowed to stand overnight to precipi-
tate the NHC silver complex 1 as fine colorless crystals
0.184 g (49%). m.p.: 179–181 ꢁC. Anal. Calc. for
C30H44Ag2Cl2N4: C, 48.21; H, 5.93; N, 7.50. Found: C,
48.67; H, 5.66; N, 7.83. 1H NMR (CDCl3, 25 ꢁC), d,
ppm: 7.50–7.54 (4H, m, Ar), 7.28–7.46 (4H, m, Ar), 4.40
(8H, t, J = 7.4 Hz, NCH2), 1.81–1.84 (8H, m, CH2),
1.30–1.41(8H, m, CH2), 0.98–1.01(12H, t, J = 7.4 Hz,
CH3). EI-MS (70 equiv., based on Ag107): m/z (relative
A similar procedure to the synthesis of N,N0-dibutyl-
benzimidazolylidene silver chloride using THF as solvent
was adopted with N,N0-dibutylbenzimidazolium iodide
(0.359 g, 1.0 mmol), 2 equiv. Ag2O (0.464 g, 2 mmol) and
AgNO3 (0.085 g, 0.5 mmol) to provide 4 as pale yellow
crystals (0.20 g, 63%). m.p.: 120–123 ꢁC (dec.). Anal. Calc.
for C30H44N5O3Ag Æ 1.5H2O: C, 54.74; H, 7.15; N, 10.64.
Found: C, 54.27 H, 7.05; N, 10.29. 1H NMR (CDCl3,
25 ꢁC), d, ppm: 7.55–7.62 (4H, m, Ar), 7.42–7.78 (4H, m,
Ar), 4.50 (8H, t, 7.5 Hz, NCH2), 1.98 (8H, m, CH2), 1.45
(8H, m, CH2), 1.02 (12H, m, CH3). EI-MS (70 equiv.,
based on Ag107): m/z (relative intensity): 232 (25%)
[NHC+2]+, 189 (99%), 132 (100%).
4.8. X-ray crystal structure determination
The single crystals of complexes 1–4 suitable for X-ray
diffraction study were grown from CH2Cl2 (1 and 2),
CH3CN (3 and 4). The X-ray diffraction intensity data of
1–4 were collected with a Bruker Smart diffractometer at
intensity):
514
(1%)
[MꢀNHC]+,
337
(38%)
[MꢀAgCl2ꢀNHC]+, 265 (12%), 230 (100%) [NHC]+.

W. Huang et al. / Journal of Organometallic Chemistry 692 (2007) 3804–3809
3809
Table 2
Crystal data and refinements for complexes 1–4
Entry
1
2
3
4
Formula
C30H44Ag2Cl2N4
747.33
0.50 · 0.43 · 0.21
Monoclinic
P2(1)/n
11.7939(8)
16.6950(11)
17.4605(12)
90
108.0320(10)
90
C30H44Ag2Br2N4
836.25
0.52 · 0.39 · 0.12
Monoclinic
P2(1)/n
11.7259(17)
16.902(3)
17.858(3)
90
106.986(3)
90
C32H44Ag2N6
728.47
0.49 · 0.47 · 0.21
Monoclinic
P2(1)/n
11.5708(8)
17.0068(12)
17.8225(13)
90
105.0110(10)
90
C90H142Ag3N15O14
1981.80
0.5 · 0.39 · 0.28
Triclininc
Formula weight
Crystal size (mm)
Crystal system
Space group
ꢀ
P1
˚
a (A)
16.7782(12)
19.1889(13)
20.0486(14)
103.0530(10)
106.8820(10)
110.3820(10)
5391.4(7)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
3269.1(4)
4
1.518
3384.9(9)
4
1.641
3387.5(4)
4
1.428
Z
Dcald (Mg/m3)
F(000)
1.221
2080
1520
1664
1488
Number of reflections collected
Unique reflections
Number of parameters
Goodness-of-fit
Final R, wR2
19002
7088
333
1.008
0.0577, 0.1595
0.987, ꢀ0.605
19424
7305
297
0.881
0.0870, 0.2470
1.530, ꢀ1.186
19797
7383
330
0.972
0.0670, 0.1980
0.829, ꢀ0.563
30803
21838
1112
0.916
0.0767, 0.2359
1.914, ꢀ0.689
ꢀ3
˚
Dqmax, Dqmin (e A
)
¨
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20 ꢁC using Mo Ka radiation with an x–2h scan mode.
Crystallographic data and details of the procedures used
for data collection and reduction information are compiled
in Table 2.
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Acknowledgement
We thank the Natural Science Foundation of China for
financial support (20402006).
Appendix A. Supplementary material
[14] E. C¸ etinkaya, P.B. Hitchcock, H. Kuc¸ukbay, M.F. Lappert, S. Al-
¨ ¨
CCDC 631860, 631861, 631862 and 631863 contain the
supplementary crystallographic data for 1, 2, 3, and 4.
These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK, fax: (+44) 1223-336-033, or e-
mail: deposit@ccdc.cam.ac.uk. Supplementary data associ-
ated with this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2007.05.019.
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