Synthesis and investigation of new cyclic haloamidinium salts

Article abstract of DOI:10.1515/znb-2016-0011

The presented work describes the synthesis of new six- and seven-membered haloamidinium salts and their reaction with different metals. The isolated metal complexes were tested in a catalytic reaction. Two different synthetic routes were applied to prepare five different salts. Chloroamidinium salts were very water-sensitive in comparison to their corresponding bromoamidinium salts. Hence, the preparation of the less sensitive bromoamidinium salts was higher prioritized. The formed salts were converted with metal sources to N-heterocyclic carbene (NHC) metal complexes through an oxidative insertion into the C-X bond. This type of formation is less examined for the synthesis of extended NHC metal complexes. Pd(PPh₃)₄ and cobalt powder were applied as metal sources, whereby two palladium complexes were isolated, characterized, and their crystal and molecular structures determined. The palladium complexes were investigated in the Suzuki-Miyaura reaction and showed promising catalytic activity.

Full text of DOI:10.1515/znb-2016-0011

Z. Naturforsch. 2016; 71(6)b: 667–676
ESdyuanrdtRhaise, UslirischaFlönrkde ainnd RveenésWtiilhgelam*tion of new cyclic
haloamidinium salts
DOI 10.1515/znb-2016-0011
more stable complexes that are less sensitive to dissocia-
tion, air, and elevated temperature. In addition, NHCs
offer higher electron-donating properties [3], which could
even be increased through expanding the heterocyclic
ring from five- to six- and seven-membered analogues
[4–6]. Furthermore, complexes are formed with a variety
of metals, and also high oxidation states of the metals are
stabilized [7].
The most common procedure for the synthesis of NHC
metal complexes is a ligand exchange, but this requires the
existence of the free NHC (often formed in situ) (Scheme 1).
In many cases, the complex formation occurs through the
reaction of the free carbene with a metal complex (a) [8],
the reaction of an imidazolium salt with a transition metal
complex that possesses a basic anion or function (b) [2],
with a carbene transfer reagent via transmetalation (c) [9],
or with an imidazolium salt that is mixed with a transition
metal salt in the presence of a base (d) [10].
Received January 11, 2016; accepted February 2, 2016
Abstract: The presented work describes the synthesis of
new six- and seven-membered haloamidinium salts and
their reaction with different metals. The isolated metal
complexes were tested in a catalytic reaction. Two differ-
ent synthetic routes were applied to prepare five different
salts. Chloroamidinium salts were very water-sensitive
in comparison to their corresponding bromoamidinium
salts. Hence, the preparation of the less sensitive bro-
moamidinium salts was higher prioritized. The formed
salts were converted with metal sources to N-heterocyclic
carbene (NHC) metal complexes through an oxidative
insertion into the C–X bond. This type of formation is
less examined for the synthesis of extended NHC metal
complexes. Pd(PPh3)4 and cobalt powder were applied as
metal sources, whereby two palladium complexes were
isolated, characterized, and their crystal and molecular
structures determined. The palladium complexes were
investigated in the Suzuki-Miyaura reaction and showed
promising catalytic activity.
The previously mentioned methods are less suitable
for (thermally) labile and difficult to handle ligands (e.g.
acyclic carbene ligands). Additionally, they require a spe-
cific acidity of the carbene precursors. Some other less
Keywords: amidinium salts; N-heterocyclic carbene common methods are the cleavage of electron-rich olefins
(NHC) metal complexes; oxidative addition; Suzuki (e) [11], an α-elimination (f) [12], and an oxidative addition
cross-coupling.
(g) [13] (Scheme 2).
Early research on the complex formation via oxida-
tive addition was carried out by Lappert [14] and Stone
[15]. This method enables an access to diamino- and
Fischer-type carbene complexes with electron-rich tran-
sition metals (Ni, Pd, Pt) that are difficult to obtain with
other procedures (Scheme 3) [16]. In comparison to other
complex formation methods, this is the only case where
the oxidation state of the metal is additionally increased.
Fürstner et al. [16] were able to prepare several NHC-Pd
complexes via this route, and Arduengo et al. [17] synthe-
sized a bimetallic complex.
Normally, the complex formation takes place with
2-haloimidazolium salts, whereby the halogen is often
chlorine. There are only a few examples with bromine
[18] or iodine [19]. 2-Chloroimidazolium salts can be easily
generated from urea and thiourea compounds when
they are treated with phosgene [20], oxalyl chloride [21],
phosphoryl chloride [22], or phosphorous pentachloride
[23] (Scheme 4). 1,3-Disubstituted-2-chloro-imidazolium
1 Introduction
The history of the discovery of N-heterocyclic carbenes
(NHCs) and their broad application as ligands, cata-
lysts, and reagents shows the importance of this class of
compounds, which rose continuously over the last two
decades [1]. Herrmann et al. [2] were the first who applied
an NHC-Pd complex as catalyst for a Heck reaction. Since
then, phosphane ligands were increasingly replaced by
NHCs in many reactions. They have the advantage to be
*Corresponding author: René Wilhelm, Department Chemie,
Universität Paderborn, Warburger Straße 100, 33098 Paderborn,
Germany, Fax: +49 5251 603 245, E-mail: rene.wilhelm@upb.de
Eduard Rais and Ulrich Flörke: Department Chemie, Universität
Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
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ꢀꢀꢀꢁ
668ꢀ
ꢀE. Rais et al.: Synthesis and investigation of new cyclic haloamidinium salts
R
R
N
N
[Pd(cod)I2]
2
2
2
Pd(OAc)2
R
N
R
N
N
R
N
R
I
I
Pd
I
a
b
N
R
N
R
PdI2
K2CO3
R
R
N
R
N
Ag2O
N
[Pd(cod)I2]
d
2
AgI
c
N
N
R
N
R
I
I
R
Scheme 1:ꢀCommon procedures for the synthesis of NHC metal complexes.
R
N
R
N
R
N
R
N
2 Results and discussion
H
Cl
X
R'
N
R
N
R
N
R
N
R
2.1 Synthesis of the haloamidinium salts
e
f
g
MLn+1
MLn+1
MLn+2
The synthesis of the desired target molecules 2 were tried
first through the reaction of 1 with bromine according to a
procedure for five-membered rings reported by Kunz et al.
[28]. However, no product formation could be observed for
the extended amidinium salts 1 (Scheme 5).
R
N
R
N
MLn
MLnCl
N
R
N
R
X
Synthesis routes that are based on silver (I) oxide
[29, 30], NHC-CO2 adducts, or NHC-Cr(CO)5 complexes
with subsequent bromination [31] are relative expen-
sive or elaborate. For that reason, a pathway based on a
thiourea derivative was chosen. Starting from 3 or 6, the
corresponding diimines 4 and 7 were formed with benz-
aldehyde in excellent yields of 97% and 95%, respectively
[32]. The following reduction with NaBH4 proceeded to 5
and 8 in excellent yields of 96% and 97%, respectively
(Scheme 6) [33].
Scheme 2:ꢀFurther methods for the formation of NHC metal
complexes.
Cl
C M
Cl
MLn+2
Me2N
Me2N
H
L
n
C
Cl
Cl
H
PPh3
Pd Cl
Cl
N
N
N
Pd(PPh3)4
Cl
Cl
∆
N
−3 PPh3
The formation of thiourea 9 was attempted with 5
through the reaction with thiophosgene, but the isolated
Scheme 3:ꢀExamples of metal complexes with an Fischer carbene
(top) and with an NHC (bottom).
COCl2, (COCl)2,
POCl3 or PCl5
R'
Cl
H
Br
Br2
R
R
R
R
Mes
Mes
Br
Mes
Mes
Br3
N
N
N
N
R' = O or S
N
N
N
N
Cl
CHCl3, 20 °C, 16 h
n
n
Scheme 4:ꢀSynthesis of 2-chloroimidazolium salts with chlorination
agents.
1
2
a n = 1
b n = 2
Scheme 5:ꢀAttempts to form 2.
salts are used as dehydrating reagents due to their strong
hygroscopic properties [24]. Furthermore, haloamidinium
salts can be used as organocatalysts [25].
Because of our interests in expanded NHC complexes
[6, 26, 27], we report here on a synthesis of new extended
NHC complexes via oxidative insertion into haloamidin-
ium salts and their application in a Suzuki cross-coupling
reaction.
O
Ph
Ph
Ph
Ph
Ph
H
NaBH4
NH2 NH2
N
N
NH HN
H2O, 16 h
MeOH, reflux
15 min
n
n
n
n = 1 3
n = 2 6
n = 1 4 (97%)
n = 2 7 (95%)
n = 1 5 (96%)
n = 2 8 (97%)
Scheme 6:ꢀSynthesis of diamines 5 and 8.
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E. Rais et al.: Synthesis and investigation of new cyclic haloamidinium saltsꢂ
ꢂ669
yield was only 8% and there were many by-products.
Starting from 1b, the NHC was generated with
Some of them were difficult to separate by column chro- KHMDS and 2 equiv. of sulfur were added (Scheme 11).
matography. The product yield could be increased to 64% The product 17b could be isolated in 44% yield after
using carbon disulfide [34]. In addition, the workup was 16 h at room temperature in THF. When the reaction was
simplified to a recrystallization. The cyclization of 8 with carried out for 2 h in refluxing toluene, the yield was
carbon disulfide was not successful for the formation of a lowered to 32%. Thiourea 17a was synthesized under
seven-membered ring (Scheme 7).
various reaction conditions as presented in Table 1. The
The formation of the new haloamidinium salts with best results were obtained after 18 h, when KOt-Bu was
oxalyl chloride or bromide proceeded in excellent yields used in THF as solvent (Entry 3). A reaction with Na2S
(Scheme 8). The chloroamidinium chloride 11 was highly gave no product (Entry 5) [36]. The weak base and the
hygroscopic in comparison to 12.
small amount of sulfur may be a reason for the low yield
Trials to obtain dimesityl-substituted thiourea 14 from in Entry 6.
13 with thiophosgene or with carbon disulfide were not
The subsequent reaction of 17a with oxalyl chloride
successful, the starting material was recovered in both or bromide resulted in no product. A reason for this might
reactions. The reason might be the higher steric hindrance be the higher steric hindrance due to the aryl substitu-
in comparison to 9 and due to the ambient reaction condi- ents. Even an increased temperature with up to 111°C in
tions (Scheme 9).
toluene did not afford the products. All similar examples
Attempts to form 10 were also conducted with that were described in the literature are sterically less
1,3-dibenzylthiourea, with 1,4-dibromobutane, and with hindered.
different solvents and bases under various conditions and
were not successful. Efforts to get 16 via a similar route KHMDS and bromine [37], which gave the desired product
from 15 were also not successful (Scheme 10) [35].
A more simple approach was the treatment of 1 with
in up to 79% yield (Scheme 12).
S
S
Cl
Cl
S C S
Ph
NH HN
Ph
Ph
N
N
Ph
Ph
NH HN
Ph
CH2Cl2, NEt3
20 °C, 3 h
8%
Pyridine,
reflux, 24 h
64%
5
9
5
S
S
C S
Ph
Ph
Ph
NH HN
Ph
N
N
Pyridine,
reflux, 24 h
10
8
Scheme 7:ꢀFormation of thiourea 9 and attempts to form 10.
Cl
S
Br
(COCl)2
(COBr)2
Ph
N
N
Ph
Ph
N
N
Ph
Ph
N
N
Ph
Toluene,
60 °C, 16 h
91%
Toluene,
60 °C, 16 h
99%
Cl
Br
11
12
9
Scheme 8:ꢀSynthesis of the haloamidinium salts 11 and 12.
S
S
Mes
Mes
Mes
Mes
Cl
Cl
S
C
S
Mes
Mes
N
N
N
N
N
N
H
H
H
H
Pyridine,
reflux, 24 h
CH2Cl2, NEt3,
−78 to 20 °C, 40 h
13
14
13
Scheme 9:ꢀAttempts for the formation of 14.
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670ꢀ
ꢀE. Rais et al.: Synthesis and investigation of new cyclic haloamidinium salts
X
Br
Br
S
S
X
X Pd PPh3
K2CO3, TBAB
Pd(PPh3)4
Ph
Ph
Ph
Ph
X = Cl 19
X = Br 20
N
N
H
N
N
Ph
N
N
Ph
Ph
N
N
Ph
H
THF, 20 °C, 48 h
Toluol, 100 °C, 2 h
X
−3 PPh3
15
16
X = Cl 63%
X = Br 74%
Scheme 10:ꢀAttempted cyclization of 15.
Scheme 13:ꢀSynthesis of Pd complexes.
S
Base
S8
Mes
Mes
Br
Mes
Mes
N
N
N
N
Solvent
n
n
1
17
a n = 1
b n = 2
Scheme 11:ꢀSynthesis of dimesityl-substituted thiourea 17.
Table 1:ꢀReagents and reaction conditions for Scheme 11.
Entryꢁ Base
ꢁ
n(S8)ꢁ Solvent ꢁ Temperatureꢁ Yield
(equiv.)
(°C)
(%)
1
2
3
4
5
6
7
ꢃ KHMDS (1 equiv.)
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
4ꢃ Toluene ꢃ
20ꢃ
20ꢃ
20ꢃ
20ꢃ
20ꢃ
65ꢃ
65ꢃ
66
21
80
39
0
ꢃ KHMDS (2 equiv.)a
ꢃ KOt-Bu (1 equiv.)
ꢃ NaH (1 equiv.)
1.5ꢃ THF
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
1ꢃ THF
1ꢃ THF
ꢃ KHMDS (1 equiv.)
ꢃ K2CO3 (1 equiv.)
ꢃ Pyridine (6.7 equiv.)ꢃ
+ DBU (4.5 equiv.)
–bꢃ THF
c
0.125ꢃ MeOH
3ꢃ MeOH
–
41
Fig. 1:ꢀMolecular structure of 19 in the crystal. Anisotropic displace-
ment ellipsoids are drawn at the 50% probability level, and hydro-
gen atoms and solvent molecules are omitted.
aThe carbene was generated at –78°C, and the reaction mixture was
subsequently warmed up to room temperature. bNa2S (1.85 equiv.)
was added 30 min after KHMDS instead of S8; ctraces of product
were found but not isolated.
1. KHMDS
2. Br2
Br
18c 79%
18a 72%
18b 49%
Mes
Mes
Br
Mes
Mes
N
N
N
N
Benzene
20 °C, 16 h
Br
n
n
c n = 0
a n = 1
b n = 2
1
18
Scheme 12:ꢀFormation of bromoamidinium salts 18 with bromine.
2.2 Synthesis of the NHC-metal complexes
The haloamidinium salts 11 and 12 were mixed with
Pd(PPh3)4 and heated in toluene at 100°C (Scheme 13).
After workup, two complexes could be isolated as crystals,
which were suitable for X-ray crystal structure analysis
(Figs. 1 and 2). In both cases, a neutral, quadratic-planar
palladium complex with one NHC, one PPh3, and two
halide ligands was formed. The configuration was cis in
contrast to the result of Fürstner et al. [16], who obtained
Fig. 2:ꢀMolecular structure of 20 in the crystal. Anisotropic dis-
placement ellipsoids are drawn at the 50% probability level, and
trans-configured complexes with one six-membered NHC hydrogen atoms and solvent molecules are omitted.
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ꢂ671
ligand incorporating smaller methyl substituents on the
With1-bromo-3,5-dimethylbenzene, highyieldsof86%
nitrogen atoms. Furthermore, their complex was posi- and 93% were obtained, respectively (Entries 1 and 2). The
tively charged and coordinated by a second PPh3 ligand. change of the aryl halide and the base enhanced the yields
The reaction of 1a with Pd(PPh3)4 did not yield isolable (Entries 3 and 4). The use of 4-methoxyphenylboronic acid
complexes under the mentioned conditions.
and a shorter reaction time decreased the yields of entries
In addition, the haloamidinium salts 18a–c were 5 and 6 in comparison to entries 3 and 4. Low yields were
mixed with cobalt powder (20 equiv.; particle size ꢀ<ꢀ150 always obtained, when m-chloro- or m-bromotoluene was
μm) and heated in different solvents. The only isolated used (entries 7–10). Table 2 also shows that the influence
and identified product was the cation of 1c with [CoBr4]2− of the applied base was low [41, 42]. The steric demand
and bromide anions (Scheme 14) [38]. The reaction of 12 seems to be more influential because the yield was always
with Co powder yielded a cobalt pyridinone complex [39]. lower when 1-bromo-3,5-dimethylbenzene, m-chloro- and
m-bromotoluene were used (entries 7–10). The low steric
shielding of the metal core by the freely rotating benzyl
side arms and the relatively low steric demand of the aryl
halides probably causes a slow reductive elimination
2.3 Catalytic reactions
The obtained complexes 19 and 20 were tested as poten- because the steric repulsion between the ligands is small.
tial catalysts in the Suzuki-Miyaura reaction [40]. The The decelerated reductive elimination lowers the turnover
reactions with aryl halides and phenylboronic acid (1.5 frequency, so that only low yields were obtained. Increased
equiv.) were carried out in THF with 1 mol% of the respec- temperature and longer reaction time could improve the
tive complex and 2.5 equiv. of a base (Scheme 15). The results (entries 1 and 2). The use of 1-bromonaphthalene
results are summarized in Table 2.
led to high yields at room temperature (entries 3 and 4).
Furthermore, 4-methoxyphenylboronic acid was
applied as coupling partner (entries 5–10). The reactivity
differences between m-chloro- and m-bromotoluene are
low (entries 9–12). Based on the results, both complexes
showed a similar promising activity.
H
Br
Co powder
Mes
Mes
Mes
Mes
Br
N
N
[CoBr4]2
+
N
N
Br
+
MeCN, 100 °C,
40 h
18c
To investigate the stability of the complex in air, the
catalyst 20 was also applied in a reaction without inert
gas (entry 11), but the conversion was low.
Scheme 14:ꢀAttempted formation of Co NHC complexes.
The five-membered analogue in Scheme 3 gave for an
electron-deficient bromoarene a 79% yield in a Suzuki-
Miyaura reaction [16].
cat. (1 mol%)
base (2.5 equiv.)
THF
+
(HO)2B
R
Ar
R
Ar
X
Scheme 15:ꢀSuzuki-Miyaura reaction with the new Pd complexes.
Table 2:ꢀResults of the catalytic Suzuki-Miyaura reactions.
3 Conclusion
Three new haloamidinium salts were successfully synthe-
sized and characterized. Thereby an efficient route was
applied for extended haloamidinium salts. The benzyl-
substituted chloroamidinium salt 11 was obtained after
treatment of the thiourea derivate with oxalyl chloride.
Moreover, it was shown for the first time that bromoami-
Entryꢁ Catalystꢁ Aryl halide
ꢁ Base ꢁ Yield (%)
1
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
19ꢃ 1-Bromo-3,5-dimethylbenzeneꢃ Cs2CO3 ꢃ
20ꢃ 1-Bromo-3,5-dimethylbenzeneꢃ Cs2CO3 ꢃ
86a
93a
96b
2
3
19ꢃ 1-Bromonaphthalene
20ꢃ 1-Bromonaphthalene
19ꢃ 1-Bromonaphthalene
20ꢃ 1-Bromonaphthalene
19ꢃ m-Chlorotoluene
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
CsF
CsF
CsF
CsF
CsF
CsF
CsF
CsF
CsF
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
4
92b dinium salts can be produced from oxalyl bromide and the
5
54c,d
corresponding thiourea. Two new mixed Pd-extended-NHC
6
45c,d
phosphane complexes could be isolated and successfully
7
7c,d
applied in the Suzuki reaction cross-coupling reaction.
8
20ꢃ m-Chlorotoluene
11c,d
11c,d
9c,d
9
19ꢃ m-Bromotoluene
10
11
20ꢃ m-Bromotoluene
20ꢃ 1-Bromonaphthalene
11c, e
4 Experimental section
Reactions were carried out under inert gas using stand-
ard Schlenk techniques, unless mentioned otherwise.
a24 h at 50°C; b24 h at 20°C; c16 h at 20°C; d4-methoxyphenylboronic
acid instead of phenylboronic acid; ereaction was carried out
without inert gas.
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672ꢀ ꢀE. Rais et al.: Synthesis and investigation of new cyclic haloamidinium salts
All commercially available chemicals were used without was isolated as a colorless oil (12.60 g, 0.0476 mol; 95%).
further purification. Solvents were dried prior to use by The spectroscopic data were consistent with the literature
1
standard procedures. Thin layer chromatography was [47]. – H NMR (CDCl3): δ ꢀ=ꢀ 8.29 (s (broad), 2 H, Nꢀ=ꢀCH),
performed on plates from Merck (Silica gel 60, F254), sub- 7.74–7.71 (m, 4 H, ArH), 7.42–7.38 (m, 6 H, ArH), 3.70–3.65
stances were detected under UV light at 254 nm.
(m, 4 H, N–CH2), 1.84–1.78 (m, 4 H, N–CH2–CH2) ppm. –
NMR spectra were recorded at 30°C on a Bruker 13C NMR (CDCl3): δ ꢀ=ꢀ 160.9 (Cꢀ=ꢀN), 136.4 (ArC), 130.5 (ArC),
13
15
31
Avance 500 (1H, 500 MHz; C, 125 MHz; N, 51 MHz; P, 128.6 (ArC), 128.1 (ArC), 61.5 (N–CH2), 28.7 (N–CH2–CH2)
202 MHz) referenced to the residual proton or carbon ppm.
signals of the deuterated solvent (1H and 13C NMR). The
NMR signals are reported in ppm relative to TMS. Liquid
15
ammonia was used as an external reference for N NMR. 4.2 General procedure for the synthesis of
Phosphoric acid (85%) was used as an external reference
diamines
for 31P NMR. Mass spectrometry was carried out on Waters
Quadrupole-ToF Synapt 2G using electrospray ionization The diimine (1 equiv.) was dissolved in methanol (50
(ESI). IR spectra were recorded on a Bruker Vertex 70 mL), after that NaBH4 (2 equiv.) was added in small por-
spectrometer. Elemental analyses were performed on an tions to the reaction vessel. The mixture was refluxed for
Elementar vario MicroCube analyzer. Melting points were 15 min; after cooling, water (70 mL) was added carefully.
measured with a Büchi Melting Point B-545 apparatus.
The aqueous phase was extracted with dichloromethane
1a [43], 1b [29], 1c [44], 13 [43], and 15 [45] were syn- (3 ꢀ×ꢀ 50 mL). The combined organic phases were dried over
thesized according to literature procedures, and spectral K2CO3, and the solvent was removed under reduced pres-
data were consistent.
sure to yield the product.
4.1 General procedure for the synthesis of
diimines
1
3
4.2.1 N ,N -Dibenzylpropane-1,3-diamine (5)
NaBH4 (3.69 g, 0.098 mol) was added to a solution of
4 (12.22 g, 0.048 mol) in methanol. After workup, the
product was isolated as a pale yellow oil (11.87 g, 0.047
mol; 96%). The spectroscopic data were consistent with
Diamine (0.05 mol), benzaldehyde (10.1 mL, 0.1 mol), and
water (30 mL) were stirred vigorously for 16 h without inert
gas. Afterward, the emulsion was extracted with dichlo-
romethane (3 ꢀ×ꢀ 100 mL). The combined organic phases
were dried over MgSO4 and the solvent was removed under
reduced pressure to yield the product.
1
the literature [46]. – H NMR (CDCl3): δ ꢀ=ꢀ 7.35–7.31 (m, 8
H, ArH), 7.27–7.24 (m, 2 H, ArH), 3.79 (s, 4 H, N–CH2-Ph),
2.72 (t, J ꢀ=ꢀ 6.7 Hz, 4 H, CH2–CH2–CH2), 1.74 (quint, J ꢀ=ꢀ 6.7
Hz, 2 H, CH2–CH2–CH2), 1.49 (s (broad), 2 H, NH) ppm. –
13C NMR (CDCl3): δ ꢀ=ꢀ 140.6 (ArC), 128.4 (ArC), 128.1 (ArC),
126.9 (ArC), 54.1 (N–CH2-Ph), 48.0 (CH2–CH2–CH2), 30.3
(CH2–CH2–CH2) ppm.
1
3
4.1.1 N ,N -Dibenzylidenepropane-1,3-diamine (4)
Propane-1,3-diamine (4.17 mL), benzaldehyde, and water
were reacted at room temperature. After workup, the product
was isolated as a colorless oil (12.22 g, 0.0487 mol; 97%). The
1
3
spectroscopic data were consistent with the literature [46]. 4.2.2 N ,N -Dibenzylpropane-1,3-diamine (8)
– 1H NMR (CDCl3): δ ꢀ=ꢀ 8.31 (s (broad), 2 H, Nꢀ=ꢀCH) , 7.76 –7.7 2
(m, 4 H, ArH), 7.43–7.40 (m, 6 H, ArH), 3.73 (dt, J ꢀ=ꢀ 7.0 Hz, 4 H, NaBH4 (3.31 g, 0.087 mol) was added to a solution of 7 (11.56
N–CH2), 2.13 (quint, J ꢀ=ꢀ 7.0 Hz, 2 H, CH2–CH2–CH2) ppm. – 13C g, 0.044 mol) in methanol. After workup, the product was
NMR (CDCl3): δ ꢀ=ꢀ 161.3 (Cꢀ=ꢀN), 136.4 (ArC), 130.5 (ArC), 128.6 isolated as a pale yellow oil (11.43 g, 0.043 mol; 97%). The
(ArC), 128.1 (ArC), 59.2 (N–CH2), 32.0 (CH2–CH2–CH2) ppm.
spectroscopic data were consistent with the literature [47].
1
– H NMR (CDCl3): δ ꢀ=ꢀ 7.40–7.22 (m, 10 H, ArH), 3.79 (s, 4
H, N–CH2-Ph), 2.67–2.62 (m, 4 H, N–CH2–CH2), 1.59–1.54
(m, 4 H, N–CH2–CH2), 1.35 (s (broad), 2 H, NH) ppm. – 13C
NMR (CDCl3): δ ꢀ=ꢀ 140.6 (ArC), 128.4 (ArC), 128.1 (ArC), 126.9
1
4
4.1.2 N ,N -Dibenzylidenebutane-1,4-diamine (7)
Butane-1,4-diamine (5 mL), benzaldehyde, and water were (ArC), 54.1 (N–CH2-Ph), 49.3 (N–CH2–CH2), 27.9 (N–CH2–
reacted at room temperature. After workup, the product CH2) ppm.
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E. Rais et al.: Synthesis and investigation of new cyclic haloamidinium saltsꢂ
ꢂ673
4.2.3 1,3-Dibenzyltetrahydropyrimidine-2(1H)-thione (9) mixture was stirred for 16 h. After filtration, the solvent
was removed under reduced pressure. After two separa-
Compound 5 (6.018 g, 0.024 mol), carbon disulfide (2.11 tions by column chromatography (n-hexane/EtOAc ꢀ=ꢀ
mL, 0.035 mol) and pyridine (20 mL) were refluxed for 8.5:1.5; Rf ꢀ=ꢀ 0.33), the product was obtained as an color-
24 h. After the volatile components were removed under less crystalline solid (77 mg, 0.212 mmol; 44%). IR (KBr):
reduced pressure, the residue was recrystallized two times v ꢀ=ꢀ 3437, 2916, 2359, 1461, 1293 cm−1. – 1H NMR (CDCl3): δ ꢀ=ꢀ
from ethanol and washed afterward with cold ethanol. 6.92 (s, 4 H, ArH), 3.88 (s (broad), 4 H, N–CH2), 2.34 (s, 12
Colorless crystals (4.534 g, 0.015 mol; 64%) were obtained H, Ar-o-CH3), 2.29 (s, 6 H, Ar-p-CH3), 2.06 (quint, J ꢀ=ꢀ 2.9 Hz,
after vacuum drying; m.p. 135°C. IR (KBr): v ꢀ=ꢀ 3437, 2906, 4 H, CH2–CH2–CH2–CH2) ppm. – 13C NMR (CDCl3): δ ꢀ=ꢀ 186.7
1
1509, 1352, 704 cm−1. – H NMR (CDCl3): δ ꢀ=ꢀ 7.41–7.32 (m, 8 (Cꢀ=ꢀS), 144.2 (ArC), 136.4 (ArC), 134.6 (ArC), 129.7 (ArC),
H, ArH), 7.30–7.25 (m, 2 H, ArH), 5.37 (s, 4 H, N–CH2-Ph), 54.7 (N–CH2), 25.8 (CH2–CH2–CH2–CH2), 21.0 (Ar-p-CH3),
3.28 (t, J ꢀ=ꢀ 6.1 Hz, 4 H, CH2–CH2–CH2), 1.88 (quint, J ꢀ=ꢀ 6.1 18.9 (Ar-o-CH3) ppm. – 15N NMR (CDCl3): δ ꢀ=ꢀ 121.6 (N–C–N)
Hz, 2 H, CH2–CH2–CH2) ppm. – 13C NMR (CDCl3): δ ꢀ=ꢀ 180.6 ppm. – HRMS ((+)-ESI): m/z ꢀ=ꢀ 367.2208 (calcd. 367.2203 for
+
(N–C–N), 137.4 (ArC), 128.6 (ArC), 127.7 (ArC), 127.4 (ArC), C23H31N2S, [M+H] ).
58.7 (N–CH2-Ph), 46.2 (CH2–CH2–CH2), 21.2 (CH2–CH2–CH2)
ppm. – 15N NMR (CDCl3): δ ꢀ=ꢀ 115.6 (N–C–N) ppm. – HRMS
((+)-ESI): m/z ꢀ=ꢀ 319.1232 (calc. 319.1240 for C18H20N2SNa, 4.2.6 General procedure for the synthesis of benzyl
+
[M+Na] ).
substituted haloamidinium salts
Pyrimidinethione 9 (1 equiv.) was stirred with oxalyl
halide (1.2 equiv.) in toluene at 60°C for 16 h. The solvent
was decanted subsequently, and the residue was washed
three times with Et2O. After vacuum-drying, the product
4.2.4 1,3-Dimesityltetrahydropyrimidine-2(1H)-thione
(17a)
Compound 1a (50 mg, 0.125 mmol) was mixed with KOt-Bu was obtained as a beige powder.
(14 mg, 0.125 mmol) and sulfur (32 mg, 0.125 mmol) in THF
(3.1 mL). The mixture was stirred for 18 h at room tempera-
ture and quenched with water (10 mL). The aqueous phase 4.2.7 1,3-Dibenzyl-2-chloro-3,4,5,6-
was extracted with CH2Cl2 (3 ꢀ×ꢀ 10 mL). The combined
organic phases were dried over Na2SO4, and the solvent
tetrahydropyrimidin-1-ium chloride (11)
was removed under reduced pressure. After column chro- Compound 9 (400 mg, 1.35 mmol) reacted with oxalyl
matography of the residue (petroleum ether/EtOAc ꢀ=ꢀ 8:2; chloride (0.138 mL, 1.62 mmol) in toluene (15 mL). The
Rf ꢀ=ꢀ 0.41) the product was obtained as colorless crystalline product (413 mg, 1.23 mmol; 91%) was highly hygroscopic
solid (35 mg, 0.099 mmol; 80%). Spectral data were con- and had to be protected from humidity; m.p. 101°C. – IR
1
sistent with literature values [48]. IR (KBr): v ꢀ=ꢀ 3433, 2949, (KBr): v ꢀ=ꢀ 3429, 3387, 1627, 1325, 757, 704 cm−1. – H NMR
1
2855, 1607, 1485, 1299, 1196, 851 cm−1. – H NMR (CDCl3): (CDCl3): δ ꢀ=ꢀ 7.43–7.34 (m, 6 H, ArH), 7.33–7.28 (m, 4 H, ArH),
δ ꢀ=ꢀ 6.92 (s, 4 H, ArH), 3.60 (t, J ꢀ=ꢀ 5.8 Hz, 4 H, N–CH2), 5.11 (s, 4 H, N–CH2-Ph), 3.94 (t, J ꢀ=ꢀ 5.8 Hz, 4 H, CH2–CH2–
2.35 (quint, J ꢀ=ꢀ 5.8 Hz, 2 H, CH2–CH2–CH2), 2.30 (s, 12 H, CH2), 2.17 (quint, J ꢀ=ꢀ 5.8 Hz, 2 H, CH2–CH2–CH2) ppm. – 13C
Ar-o-CH3), 2.29 (s, 6 H, Ar-p-CH3) ppm. – 13C NMR (CDCl3): NMR (CDCl3): δ ꢀ=ꢀ 152.9 (N–C–N), 132.6 (ArC), 129.5 (ArC),
δ ꢀ=ꢀ 177.9 (Cꢀ=ꢀS), 141.8 (ArC), 136.9 (ArC), 134.7 (ArC), 129.5 129.0 (ArC), 127.6 (ArC), 59.4 (N–CH2-Ph), 49.2 (CH2–CH2–
(ArC), 48.5 (N–CH2), 22.3 (CH2–CH2–CH2), 21.1 (Ar-p-CH3), CH2), 19.7 (CH2–CH2–CH2) ppm. – 15N NMR (CDCl3): δ ꢀ=ꢀ 127.5
17.9 (Ar-o-CH3) ppm. – 15N NMR (CDCl3): δ ꢀ=ꢀ 115.7 (N–C–N) (N–C–N) ppm. – HRMS ((+)-ESI): m/z ꢀ=ꢀ 299.1301 (calcd.
+
ppm. HRMS ((+)-ESI): m/z ꢀ=ꢀ 353.2043 (calcd. 353.2051 for 299.1310 for C18H20ClN2, [cation] ).
+
C22H29N2S, [M+H] ).
4.2.8 1,3-Dibenzyl-2-bromo-3,4,5,6-
4.2.5 1,3-Dimesityl-1,3-diazepane-2-thione (17b)
tetrahydropyrimidin-1-ium bromide (12)
KHMDS (1.06 mL, c ꢀ=ꢀ 0.5 mol L−1 in toluene, 0.529 mmol) Compound 9 (500 mg, 1.69 mmol) reacted with oxalyl
was added to a solution of 1b (200 mg, 0.481 mmol) in bromide (0.288 mL, 2.02 mmol) in toluene (20 mL) to yield
THF (7 mL) and stirred for 30 min at room temperature. the product (707 mg, 1.67 mmol; 99%); m.p. 221°C (decom-
Then sulfur (0.247 g, 0.963 mmol) was added, and the position). – IR (KBr): v ꢀ=ꢀ 3027, 2922, 1615, 1325, 753, 704
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674ꢀ
ꢀE. Rais et al.: Synthesis and investigation of new cyclic haloamidinium salts
1
cm−1. – H NMR (CDCl3): δ ꢀ=ꢀ 7.40–7.29 (m, 10 H, ArH), 5.14 spectroscopic data were consistent with the literature [37].
(s, 4 H, N–CH2-Ph), 3.85 (t, J ꢀ=ꢀ 5.8 Hz, 4 H, CH2–CH2–CH2), 1H NMR (CDCl3): δ ꢀ=ꢀ 6.98 (s, 4 H, ArH), 4.39 (t, J ꢀ=ꢀ 5.6 Hz,
2.15 (quint, J ꢀ=ꢀ 5.8 Hz, 2 H, CH2–CH2–CH2) ppm. – 13C NMR 4 H, N–CH2), 2.68 (quint, J ꢀ=ꢀ 5.6 Hz, 2 H, CH2–CH2–CH2),
13
(CDCl3): δ ꢀ=ꢀ 149.0 (N–C–N), 132.7 (ArC), 129.4 (ArC), 129.0 2.33 (s, 12 H, Ar-o-CH3), 2.30 (s, 6 H, Ar-p-CH3) ppm. – C
(ArC), 127.6 (ArC), 62.0 (N–CH2-Ph), 49.3 (CH2–CH2–CH2), NMR (CDCl3): δ ꢀ=ꢀ 148.2 (N–C–N), 140.7 (ArC), 139.4 (ArC),
19.9 (CH2–CH2–CH2) ppm. – 15N NMR (CDCl3): δ ꢀ=ꢀ 131.0 133.6 (ArC), 130.4 (ArC), 51.9 (N–CH2), 21.1 (Ar-p-CH3), 20.5
(N–C–N) ppm. – HRMS ((+)-ESI): m/z ꢀ=ꢀ 345.0789 (calcd. (CH2–CH2–CH2), 17.8 (Ar-o-CH3) ppm. – HRMS ((+)-ESI):
+
+
345.0784 for C18H20BrN2, [cation] ).
m/z ꢀ=ꢀ 399.1429 (calcd. 399.1431 for C22H28BrN2, [cation] ).
4.3 General procedure for mesityl-
substituted bromoamidinium salts
4.3.3 2-Bromo-1,3-dimesityl-4,5,6,7-tetrahydro-1H-1,
3-diazepin-3-ium bromide (18b)
The carbene precursor 1 (1 equiv.) was suspended in
benzene and treated with KHMDS solution (1.5 equiv.).
After 1 h, bromine (2 equiv.) was added under the exclusion
of light; afterward, the mixture was stirred for 16 h at room
temperature. The solid was separated with a centrifuge,
washed with benzene (2 ꢀ×ꢀ 5 mL) and with Et2O (5 mL). The
residue was dissolved in chloroform (50 mL) and washed
with water (3 ꢀ×ꢀ 20 mL). The organic phase was dried over
Na2SO4, and the solvent was removed under reduced pres-
sure. The residue was dissolved in a small amount of chlo-
roform, dropwise addition of Et2O under continuous stirring
led to precipitation of a solid. The solid was separated with
a centrifuge and washed with Et2O (5 mL). After vacuum
drying, the product could be obtained as a powder.
Compound 1b (350 mg, 0.843 mmol) in benzene (10 mL)
reacted with KHMDS (2.5 mL, c ꢀ=ꢀ 0.5 mol L−1 in toluene) and
bromine (87 μL, 1.685 mmol). The product was obtained
as a beige solid (206 mg, 0.417 mmol; 49%). IR (KBr): v ꢀ=ꢀ
1
3433, 2953, 2920, 1607, 1567 cm−1. – H NMR (CDCl3): δ ꢀ=ꢀ
6.96 (s, 4 H, ArH), 4.76 (s (broad), 4 H, N–CH2), 2.49 (quint,
J ꢀ=ꢀ 3.1 Hz, 4 H, CH2–CH2–CH2–CH2), 2.36 (s, 12 H, Ar-o-CH3),
13
2.28 (s, 6 H, Ar-p-CH3) ppm. – C NMR (CDCl3): δ ꢀ=ꢀ 152.0
(N–C–N), 141.9 (ArC), 140.4 (ArC), 133.1 (ArC), 130.6 (ArC),
58.0 (N–CH2), 23.3 (CH2–CH2–CH2–CH2), 21.0 (Ar-o-CH3),
18.2 (Ar-p-CH3) ppm. – 15N NMR (CDCl3): δ ꢀ=ꢀ 141.4 (N–C–N)
ppm. – HRMS ((+)-ESI): m/z ꢀ=ꢀ 413.1584 (calcd. 413.1587 for
+
C23H30BrN2, [cation] ).
4.4 General procedure for the synthesis of
Pd complexes
4.3.1 2-Bromo-1,3-dimesityl-4,5-dihydro-1H-imidazol-3-
ium bromide (18c)
The haloamidinium salt (0.354 mmol) was mixed with
Pd(PPh3)4 (0.408 g, 0.354 mmol) in toluene (20 mL) and
heated for 2 h at 100°C. After cooling, the solvent was
removed via condensation. The residue was stirred for
30 min with n-pentane (3 ꢀ×ꢀ 20 mL). Then the residue was
dissolved in CH2Cl2, and the insoluble components were
removed with a syringe filter. The CH2Cl2 solution was
layered with n-pentane to yield crystals after 2 days.
Compound 1c (400 mg, 1.032 mmol) in benzene (5.3 mL)
reacted with KHMDS (2.2 mL, c ꢀ=ꢀ 0.7 mol L−1 in toluene)
and bromine (106 μL, 2.064 mmol). The product was
obtained as a white solid (380 mg, 0.815 mmol; 79%). The
spectroscopic data were consistent with the literature [37].
1H NMR (CDCl3): δ ꢀ=ꢀ 6.97 (s, 4 H, ArH), 4.83 (s, 4 H, CH2),
13
2.31 (s, 12 H, Ar-o-CH3), 2.30 (s, 6 H, Ar-p-CH3) ppm. – C
NMR (CDCl3): δ ꢀ=ꢀ 151.6 (N–C–N), 141.3 (ArC), 135.2 (ArC),
130.5 (ArC), 130.3 (ArC), 52.6 (N–CH2), 21.1 (Ar-p-CH3), 17.8
(Ar-o-CH3) ppm. – HRMS ((+)-ESI): m/z ꢀ=ꢀ 385.1295 (calcd. 4.4.1 (1,3-Dibenzylhexahydropyrimidin-2-yl)
+
385.1274 for C21H26BrN2, [cation] ).
(triphenylphosphane)palladium(II)chloride (19)
Compound 11 (0.119 g) yielded pale yellow prism-shaped
crystals (0.158 g, 0.224 mmol; 63%) after workup; m.p.
270°C (decomposition). – IR (KBr): v ꢀ=ꢀ 3433, 3057, 1539,
4.3.2 2-Bromo-1,3-dimesityl-3,4,5,6-
tetrahydropyrimidin-1-ium bromide (18a)
1
704 cm−1. – H NMR (CD2Cl2): δ ꢀ=ꢀ 7.91–7.78 (m, 6 H, ArH),
Compound 1a (414 mg, 1.032 mmol) in benzene (10 mL) 7.62–7.56 (m, 3 H, ArH), 7.55–7.48 (m, 10 H, ArH), 7.41–7.32
reacted with KHMDS (2.2 mL, c ꢀ=ꢀ 0.7 mol L−1 in toluene) (m, 6 H, ArH), 6.59 (d, J ꢀ=ꢀ 14.1 Hz, 2 H, N–CH2-Ph), 4.30
and bromine (106 μL, 2.064 mmol). The product was (d, J ꢀ=ꢀ 14.1 Hz, 2 H, N–CH2-Ph), 2.85–2.77 (m, 2 H, N–CH2–
obtained as a yellow solid (356 mg, 0.741 mmol; 72%). The CH2), 2.45–2.36 (m, 2 H, N–CH2–CH2), 1.56–1.46 (m, 1 H,
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ꢁꢀꢀꢀ
E. Rais et al.: Synthesis and investigation of new cyclic haloamidinium saltsꢂ
ꢂ675
CH2–HCH–CH2), 1.39–1.26 (m, 1 H, CH2–HCH–CH2) ppm. anisotropically. Hydrogen atoms were clearly identified in
– 13C NMR (CD2Cl2): δ ꢀ=ꢀ 187.0 (d, J ꢀ=ꢀ 6.9 Hz, N–C–N), 134.8 difference syntheses, refined at idealized positions riding
(ArC), 134.6 (d, J ꢀ=ꢀ 11.0 Hz, ArC), 131.3 (d, J ꢀ=ꢀ 2.7 Hz, ArC), on the carbon atoms with isotropic displacement parame-
129.2 (ArC), 128.6 (d, J ꢀ=ꢀ 11.0 Hz, ArC), 128.5 (ArC), 128.1 ters Uiso(H) ꢀ=ꢀ 1.2 ꢀ×ꢀ Ueq(C) and C–H 0.95–0.99 Å. For 19, 0.85
(ArC), 62.6 (d, J ꢀ=ꢀ 3.2 Hz, N–CH2-Ph), 43.8 (CH2–CH2–CH2), CH2Cl2 solvent molecule per asymmetric unit was treated
19.5 (CH2–CH2–CH2) ppm. – 15N NMR (CD2Cl2): δ ꢀ=ꢀ 127.4 with the Squeeze facility of Platon [55] due to severe dis-
31
(N–C–N) ppm. – P NMR (CD2Cl2): δ ꢀ=ꢀ 26.24 (PPh3) ppm. order. In 20, 1.5 CH2Cl2 are present per asymmetric unit.
– HRMS ((+)-ESI): m/z ꢀ=ꢀ 725.0704 (calcd. 725.0842 for Table 3 contains the crystal data as well as numbers perti-
+
C36H35Cl2N2PPdNa, [M+Na] ).
nent to data collection and structure refinement. See also
below for additional crystallographic data given as Sup-
porting Information.
4.4.2 (1,3-Dibenzylhexahydropyrimidin-2-yl)
(triphenylphosphane)palladium(II) bromide (20)
CCDC 1445899 (19) and 1445900 (20) contain the sup-
plementary crystallographic data for this paper. These
data can be obtained free of charge from the Cambridge
Compound 12 (0.150 g) yielded pale yellow needle-shaped Crystallographic Data Centre via www.ccdc.cam.ac.uk/
crystals (0.208 g, 0.262 mmol; 74%) after workup; m.p. data_request/cif.
286°C (decomposition). – IR (KBr): v ꢀ=ꢀ 3433, 3053, 1543,
1
700 cm−1. – H NMR (CD2Cl2): δ ꢀ=ꢀ 7.90–7.75 (m, 6 H, ArH),
7.62–7.56 (m, 3 H, ArH), 7.54–7.44 (m, 10 H, ArH), 7.40–7.32 5 Supporting information
(m, 6 H, ArH), 6.49 (d, J ꢀ=ꢀ 14.1 Hz, 2 H, N–CH2-Ph), 4.34
(d, J ꢀ=ꢀ 14.1 Hz, 2 H, N–CH2-Ph), 2.88–2.78 (m, 2 H, N–CH2– The 1H and 13C NMR spectra of 4, 5, 7, 8, 9, 11, 12, 17a, 17b,
CH2), 2.46–2.36 (m, 2 H, N–CH2–CH2), 1.63–1.52 (m, 1 H, 18a, 18b, 18c, 19, and 20 as well as crystallographic data
CH2–HCH–CH2), 1.38–1.28 (m, 1 H, CH2–HCH–CH2) ppm.
– 13C NMR (CD2Cl2): δ ꢀ=ꢀ 188.4 (d, J ꢀ=ꢀ 9.1 Hz, N–C–N), 134.8
Table 3:ꢀCrystal structure data for 19 and 20.
(d, J ꢀ=ꢀ 11.0 Hz, ArC), 134.6 (ArC), 131.3 (d, J ꢀ=ꢀ 2.7 Hz, ArC),
129.1 (ArC), 128.5 (d, J ꢀ=ꢀ 11.0 Hz, ArC), 128.5 (ArC), 128.1
(ArC), 62.4 (d, J ꢀ=ꢀ 2.7 Hz, N–CH2-Ph), 44.0 (CH2–CH2–CH2),
19.5 (CH2–CH2–CH2) ppm. – 15N NMR (CD2Cl2): δ ꢀ=ꢀ 127.6
ꢁ
19
ꢁ
20
Formula
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
C39.40H41.80Cl8.80N2PPdꢃ C37.50H38Br2Cl3N2PPd
Mr
992.68 920.24
ꢃ
31
Cryst. size, mm3
0.37 ꢃ×ꢃ 0.20 ꢃ×ꢃ 0.08 ꢃ 0.47 ꢃ×ꢃ 0.03 ꢃ×ꢃ 0.02
(N–C–N) ppm. – P NMR (CD2Cl2): δ ꢀ=ꢀ 25.71 (PPh3) ppm.
Crystal system
Monoclinic
P21/n
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
Monoclinic
P21/c
– HRMS ((+)-ESI): m/z ꢀ=ꢀ 814.9745 (calcd. 814.9812 for
+
Space group
a, Å
C36H35Br2N2PPdNa, [M+Na] ).
9.6544(7)
15.9129(11)
22.7511(16)
94.444(2)
3484.7(4)
4
7.9014(5)
23.2167(14)
20.1717(12)
99.488(2)
3649.8(4)
4
b, Å
c, Å
β, deg
V, Å3
Z
4.5 General procedure for the Suzuki cross-
coupling reaction
D
calcd, g cm−3
1.892
1.675
Aryl halide (0.71 mmol), arylboronic acid (1.065 mmol),
base (1.776 mmol), and the catalyst (1 mol%) were stirred
in THF (2 mL). After the reaction time given in Table 2, the
suspension was chromatographed to yield the desired
coupling product. Spectral data of the coupling products
were consistent with the literature [49–52].
μ(MoKα), cm−1
F(000), e
1.292
2.992
2011
1836
hkl range
–12 ꢃꢃ≤ꢃꢃ h ꢃꢃ≤ꢃꢃ 11
–20 ꢃꢃ≤ꢃꢃ k ꢃꢃ≤ꢃꢃ 20
–29 ꢃꢃ≤ꢃꢃ l ꢃꢃ≤ꢃꢃ 29
0.66
–10 ꢃꢃ≤ꢃꢃ h ꢃꢃ≤ꢃꢃ 10
–30 ꢃꢃ≤ꢃꢃ k ꢃꢃ≤ꢃꢃ 30
–21 ꢃꢃ≤ꢃꢃ l ꢃꢃ≤ꢃꢃ 26
0.66
((sinθ)/λ)max, Å−1
Refl. measured
Refl. unique
Rint
32811
34613
8316
8722
0.0448
0.0790
Param. refined
379
424
4.6 X-ray crystal structure determinations
R(F)/wR(F2)a
0.034/0.079
0.044/0.095
(all reflexions)
GoF (F2)b
Data collections were done with
a Bruker AXS
ꢃ
ꢃ
1.029
0.63/−0.33
ꢃ
ꢃ
0.993
1.16/−1.30
Δρfin (max/min), e Å−3
SMART APEX CCD diffractometer using graphite-
monochromatized MoKα radiation. Data reduction and
absorption corrections were performed with Saint and
aR1 ꢃ=ꢃ ||Fo| – |Fc||/∑|Fo|, wR2 ꢃ=ꢃ [∑w(Fo2 – Fc2)2/∑w(Fo )2]1/2, w ꢃ=ꢃ [σ2(Fo ) +
2
2
(AP)2 + BP]−1, where P ꢃ=ꢃ (max(Fo , 0) + 2Fc2)/3; bGoF ꢃ=ꢃ [∑w(Fo2 – Fc2)2/
2
Sadabs [53, 54]. All non-hydrogen atoms were refined (nobs – nparam)]1/2
.
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ꢀꢀꢀꢁ
676ꢀ ꢀE. Rais et al.: Synthesis and investigation of new cyclic haloamidinium salts
[27] P. V. G. Reddy, S. Tabassum, A. Blanrue, R. Wilhelm, Chem.
Commun. 2009, 5910.
for 19 and 20 including the atom coordinates are given as
Supporting Information available online (DOI: 10.1515/
znb-2016-0011).
Further materials for the crystal structure deter-
mination can be found in Table 3 or in the supporting
information.
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Supplemental Material: The online version of this article
(DOI: 10.1515/znb-2016-0011) offers supplementary material,
available to authorized users.
[26] E. Rais, U. Flörke, R. Wilhelm, Acta Crystallogr. 2015, E71, 919.
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