Guanidine electron donors and silver halides: Interplay and competition between redox, coordination and polymerization reactions

Article abstract of DOI:10.1002/ejic.201101002

Redox reactions compete with coordination and polymerization reactions when the organic electron donor and ligand, 1,2,4,5-tetrakis(tetramethylguanidino) benzene (1), is dissolved together with silver halides AgX (X = Cl, Br or I) in solvents of different polarity. The complex results obtained for the relatively simple system 1/AgX highlight the importance of solvent effects. A variety of chain polymers have been synthesized in which the guanidine electron-donor building blocks are connected by silver halide clusters of different sizes. Copyright

Full text of DOI:10.1002/ejic.201101002

FULL PAPER
DOI: 10.1002/ejic.201101002
Guanidine Electron Donors and Silver Halides: Interplay and Competition
between Redox, Coordination and Polymerization Reactions
Dimitri Emeljanenko,[a] Julian Horn,[a] Elisabeth Kaifer,[a] Hubert Wadepohl,[a] and
Hans-Jörg Himmel*[a]
Keywords: Redox chemistry / Coordination compounds / Silver / Halides / Guanidine
Redox reactions compete with coordination and polymeriza-
tion reactions when the organic electron donor and ligand,
1,2,4,5-tetrakis(tetramethylguanidino)benzene (1), is dis-
solved together with silver halides AgX (X = Cl, Br or I) in
solvents of different polarity. The complex results obtained
for the relatively simple system 1/AgX highlight the impor-
tance of solvent effects. A variety of chain polymers have
been synthesized in which the guanidine electron-donor
building blocks are connected by silver halide clusters of dif-
ferent sizes.
Introduction
Aromatic compounds with amino substituents in a para
position to each other are well-known organic electron do-
nors. Examples include 1,4-bis(dimethylamino)benzene and
1,2,4,5-tetrakis(dimethylamino)benzene.[1] Oxidation of 1,4-
bis(dimethylamino)benzene leads to “Wurster’s blue”,
which was described as early as the end of the 19th cen-
tury.[2] Recently, aromatic compounds functionalized by
several guanidino groups in a para position to each other
(GFA-n, whereby n denotes the number of guanidino sub-
stituents) were introduced as a new class of strong organic
electron donors.[3–9] Two examples for GFA-4 compounds
are 1,2,4,5-tetrakis(tetramethylguanidino)benzene[3] (1) and
1,2,4,5-tetrakis(N,NЈ-dimethyl-N,NЈ-ethyleneguanidino)ben-
zene[9] (2) (see Scheme 1). In comparison to the correspond-
ing amines, 1 and 2 are much stronger Brønsted bases and
exhibit a higher reduction capacity. For example, the oxi-
dation potential E1/2(CH2Cl2) = 0.063 V for 1,2,4,5-tetra-
kis(dimethylamino)benzene[10] but –0.32 V for 1[3] with re-
spect to SCE. In addition, as shown in a massive body of
work, guanidines are versatile ligands that have been used
extensively for the synthesis of molecular compounds for
manifold applications (e.g., catalysis or deposition of mate-
rials from precursors).[11–15]
Scheme 1.
represent Brønsted bases, and in fact protonation can be
considered the simplest model for complex formation.
However, compounds such as 1 or 2 represent superior or-
ganic Brønsted bases, much stronger than amines, for exam-
ple, and therefore readily deprotonate weak proton acids
and solvents such as CH3CN if supporting conditions {e.g.,
the presence of [Au(PPh3)Cl]} are fulfilled.[9] In the past we
reported several examples of the chemistry of 1, in which
oxidation and coordination are coupled.[4,5] This is possible
because 1 could act as a ligand even after two-electron oxi-
dation, thereby underlining its extremely strong Lewis base
character. For example, treatment of a solution of 1 with
Cu(BF4)2 in CH3CN yielded a dinuclear complex of the
guanidine dication, [1{Cu(NCCH3)4}2](BF4)6.[4] In this
case, a redox reaction is coupled with coordination. On the
other hand, Brønsted acid–base reactions compete with co-
ordination reactions and usually also with redox reactions.
One example is provided by the treatment of a solution of
2 with [AuCl(PPh3)] and PhCCH in CH3CN.[16] In this case,
the redox channel that leads to the salt 2[Au(CCPh)2]2 and
the Brønsted acid–base channel that leads to the neutral Au
complex [Au(PPh3)CCPh] exhibit similar kinetics in
CH3CN. Consequently, a roughly equimolar mixture of
GFA-4 compounds such as 1 could be engaged in dif-
ferent reaction types like redox reactions, Brønsted acid–
base reactions and reactions to give coordination com-
pounds. In some cases, they compete with each other, and
in others they are coupled. Of course, N ligands generally
[a] Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität
Heidelberg,
Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
Fax: +49-6221-545707
E-mail: hans-jorg.himmel@aci.uni-heidelberg.de
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201101002.
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both product types results. Of course, the solvent is of great
importance, and highly polar solvents favour the redox
channel.
Herein we present examples of the chemistry of 1 in
which coordination, redox and polymerization reactions in-
terplay and/or compete with each other. Variations in the
experimental conditions, especially the polarity of the sol-
vent, favour one channel over the other. Oxidation of the
guanidine is accompanied by an intense green colouring of
the solution. The reaction between a silver halide and a
guanidine, which at first glance appears to be very simple,
will be shown to be a complex story. Chain polymers that
contain ordered arrays of silver halide clusters connected
through guanidine electron-donor units are among the
structurally characterized products.
Figure 1. UV/Vis spectrum of (1)Br2 dissolved in CH3CN.
Results and Discussion
In the following we discuss the reactions of 1 with silver
halides in solvents of different polarities. In the reaction
equations we took care to ensure that the stoichiometry of
the reactants is correct; they generally are not balanced.
The yields refer to the isolated crystalline material and are
therefore generally lower bounds for the actual yield. Due
to the manifold possible reaction pathways, most reaction
products cannot be foretold; however, it will be shown that
the reactions could be directed in one direction by optimi-
zation of the reaction conditions.
Reactions in MeOH
When 1 was treated with AgCl or AgBr at room temp.
in MeOH, the solution turned, after a few minutes, a deep
green that is characteristic of oxidized 1. The analytical
data (see the Experimental Section) show the products to
be the salts (1)X2 [X = Cl or Br, formed according to Equa-
tion (1)]. Hence the 1H NMR spectra of a solution of
(1)Br2 in CD3CN displays signals of the dication 12+
(methyl groups and aromatic C–H) at δ = 2.88 and
5.16 ppm.
Figure 2. Structures of the salts (1)Cl2 and (1)Br2. Thermal ellip-
soids drawn at the 50% probability level. Selected structural param-
eters {(bond lengths [pm], bond angles [°]) for (1)Cl2: N1–C1
129.9(2), N1–C7 137.0(2), N2–C7 133.4(3), N3–C7 134.0(3), N4–
C2 133.8(2), N4–C12 134.8(2), N5–C12 133.9(2), N6–C12 134.9(2),
N7–C4 130.3(2), N7–C17 136.4(2), N8–C17 135.0(2), N9–C17
(1)
1
For comparison, the H NMR spectroscopic signals of
the neutral guanidine 1, also dissolved in CD3CN, occur at 132.9(2), N10–C5 134.7(2), N10–C22 134.6(2), N11–C22 135.1(2),
N12–C22 134.2(2), C1–C2 150.2(2), C1–C6 141.6(2), C2–C3
137.6(2), C3–C4 142.2(2), C4–C5 150.6(2), C5–C6 137.2(2); C1–
δ = 2.63 and 5.54 ppm, and that of the dication in 1(I3)2 at
δ = 2.88 and 5.17 ppm.[3] The UV/Vis spectrum of (1)Br2
N1–C7 129.44(15), C2–N4–C12 122.79(14), C4–N7–C17
dissolved in CH3CN (see Figure 1) contains three strong
125.48(15), C5–N10–C22 122.59(14), N2–C7–N3 121.09(17), N5–
absorptions centered at λ = 218, 293 and 416 nm. In ad-
dition, a weak and broad feature occurs at 589 (614) nm
(see inset in Figure 1). Single crystals of (1)Cl2 and
(1)Br2·4MeOH suitable for XRD were obtained from
CH3CN/Et2O and MeOH/Et2O solutions, respectively. Fig-
C12–N6 118.74(16), N8–C17–N9 121.17(15), N11–C22–N12
118.68(15). Selected structural parameters (bond lengths [pm],
bond angles [°]) for (1)Br2: N1–C1 135.17(19), N1–C4 133.97(19),
N2–C4 135.26(19), N3–C4 134.75(19), N4–C2 130.64(19), N4–C9
136.94(19), N5–C9 134.30(19), N6–C9 132.65(19), C1–C2 149.9(2),
C1–C3 137.3(2), C2–C3Ј 141.8(2); C1–N1–C4 122.58(13), N2–C4–
ure 2 illustrates the structures. As known from other salts, N3 117.96(13), C2–N4–C9 125.54(13), N5–C9–N6 121.13(13).
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Guanidine Electron Donors and Silver Halides
the guanidine dication can be described as a pair of bisgu- was observed. Instead, the guanidine acted as a chelating
anidino-allyl monocations that are connected by two C–C ligand and pale yellow coordination polymers [1(AgX)2]n
single bonds [distances of 150.2(2) and 150.6(2) pm for C1– (X = Br or I) were formed; see Equation (3). Crystals of the
C2 and C4–C5 in (1)Cl2, and of 149.9(2) pm for C1–C2 in chain polymer [1(AgBr)2]n suitable for single-crystal X-ray
(1)Br2]. Treatment of 1 with AgI yielded a product mixture diffraction (XRD) were grown from concentrated CH3CN
from which we isolated in a crystalline yield of 51% a solutions. The structure is illustrated in Figure 4. Each AgI
brown-red chain polymer of the formula [1(Ag6I8)]n; see is tetrahedrally coordinated by two N and two Br atoms.
Equation (2). The polymer is insoluble in CH3CN, but to The dihedral angle between the N–Ag–N and Br–Ag–Br
some degree soluble in DMF. Crystals of this polymer were planes is close to the ideal value of 90° for tetrahedral coor-
obtained with and without cocrystallized DMF solvate mo- dination. All polymer chains run into the same direction
lecules. Fractions of the obtained structures are visualized (see Figure 4). The Ag–N bond lengths measure 236.0(2)
in Figure 3. It can be seen directly that the structures are and 233.8(2) pm. With 72.6(1)°, the N–Ag–N bond angles
significantly different. In the case of [1(Ag6I8)·2DMF]n, the are relatively small. The Br–Ag–Br angles [100.3(3)°] are
chain can formally be regarded to consist of [1(AgI2)2] units close to the ideal value for tetrahedral coordination. The
fused together by neutral chair-type-structured Ag4I4 clus- polymer [1(AgI)2]n was obtained in a similar way by reac-
ters. The organic building blocks are directly incorporated tion between 1 and two equivalents of AgI in CH3CN solu-
into the main chain of the polymer. In the case of solvate- tions. Crystals of [1(AgI)2·4DMF]n were obtained after sev-
free crystals of [1(Ag6I8)]n, chains of rhombic Ag2I2 units
connected through the corners can be identified. Every sec-
ond rhombic unit is bound through the Ag atoms to two
[1(AgI2)2] units. Hence in this case the organic building
blocks are not incorporated into the polymer main chain.
(3)
(2)
Figure 3. Fractions of the crystal structures of the coordination
polymers (a) [(1)Ag6I8·2DMF]n and (b) [(1)Ag6I8]n (hydrogen
atoms omitted). Thermal ellipsoids drawn at the 50% probability
level.
Figure 4. A part of the structure of the coordination polymer
[1(AgBr)2]n (hydrogen atoms omitted). The alignment of the one-
dimensional polymers is shown below. Thermal ellipsoids drawn
at the 50% probability level. Selected structural parameters (bond
lengths [pm], bond angles [°]): Ag–Br1 273.23(7), Ag–Br1Ј
268.47(8), Ag–N1 236.0(2), Ag–N4 233.8(2), N1–C1 140.9(3), N1–
C4 130.9(3), N2–C4 138.3(3), N3–C4 136.5(3), N4–C2 141.0(3),
N4–C9 131.5(3), N5–C9 138.0(3), N6–C9 135.4(3), C1–C2
140.7(3), C1–C3 139.3(3), C2–C3Ј 140.0(3); N1–Ag–N4 72.63(7),
Reactions in CH3CN
Reactions in CH3CN proceeded very differently. Hence
in the case of AgBr and AgI, no oxidation of guanidine 1 Br1–Ag–Br1Ј 100.25(3).
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eral weeks from concentrated DMF solutions. The structure [1(Ag4Cl6)·2CH2Cl2]n. Both compounds decompose in
is visualized in Figure 5. The polymer chains are structur- MeOH solutions. The analytical data indicate formation of
ally similar to those in [1(AgBr)2]n. The cocrystallized DMF AgCl and (1)Cl2 as decomposition products.
molecules separate two adjacent polymer chains. Unlike
[1(AgBr)2]n, every second chain in [1(AgI)2·4DMF]n is tilted
by approximately 90° around the chain axis (see Figure 5).
(4)
Figure 6. (a) Molecular structure of [1(AgCl)2] (hydrogen atoms
omitted). Thermal ellipsoids drawn at the 50% probability level.
Figure 5. A part of the structure of the coordination polymer
Selected structural parameters (bond lengths [pm], bond angles [°]):
[1(AgI)2]n (hydrogen atoms omitted). The alignment of the one-
Ag–Cl 237.12(11), Ag–N1 226.3(2), Ag–N4 232.9(2), N1–C1
dimensional polymers is shown below. Thermal ellipsoids drawn
142.4(3), N1–C4 131.6(4), N2–C4 136.4(3), N3–C4 137.0(4), N4–
at the 50% probability level. Selected structural parameters (bond
C2 141.4(3), N4–C9 130.9(4), N5–C9 137.3(4), N6–C9 136.1(4),
lengths [pm], bond angles [°]): Ag–I1 276.49(7), Ag–I1Ј 291.83(8),
C1–C2 141.6(4), C1–C3Ј 139.2(4), C2–C3 139.5(4); N1–Ag–N4
Ag–N1 234.31(18), Ag–N4 237.17(18), N1–C1 141.1(2), N1–C11
75.07(8), Cl–Ag–N1 153.81(6), Cl–Ag–N4 131.01(6).
131.8(3), N2–C11 136.7(2), N3–C11 136.4(3), N4–C2 141.4(2), N4–
C16 130.4(3), N5–C16 137.5(2), N6–C16 137.9(3), C1–C2 140.9(3),
C1–C3Ј 139.6(3), C2–C3 139.3(3); I1–Ag–I1Ј 110.74(3), N1–Ag–
N4 73.92(6).
For treatment of AgCl with 1, a product mixture was
obtained. In a crystalline yield of 23%, compound
[1(AgCl)2] was isolated, which is a dinuclear coordination
compound, unlike the polymers of similar overall formula
obtained in the reactions with AgBr or AgI. Its structure is
illustrated in Figure 6. The molecular units are arranged in
stacks. In addition, the salt (1)Cl2 (11% yield) and the chain
polymer [1(Ag4Cl6)]n (21% yield) were formed; see Equa-
tion (4). The latter was crystallized either from CHCl3 as
[1(Ag4Cl6)·4CHCl3]n or from CH2Cl2 as [1(Ag4Cl6)·
2CH2Cl2]n. The structures of the polymers with CHCl3 and
CH2Cl2 solvate molecules are compared in Figure 7. The
chains found in both compounds could be considered to
consist of a cationic polymer {[1(AgCl)2]2+}n in which the
building blocks are connected by halide bridges. The silver
and halide atoms of each [1(AgCl)2]2+ unit interact with
two [AgCl2]– anions. However, the conformation of the
Figure 7. Parts of the crystal structures of the coordination poly-
chains differs significantly. Hence the dihedral angle be-
mers (a) [1(Ag4Cl6)·4CHCl3]n and (b) [1(Ag4Cl6)·2CH2Cl2]n (hydro-
tween the central Ag2Cl2 ring plane and the N–Ag–N pla-
nes amounts to 72° in [1(Ag4Cl6)·4CHCl3]n, and 34° in ability level.
gen atoms omitted). Thermal ellipsoids drawn at the 50% prob-
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Guanidine Electron Donors and Silver Halides
Reactions in Toluene
If the reaction between 1 and AgCl was carried out in
toluene, only the coordination compound [1(AgCl)2] with a
neutral guanidine ligand was formed in 77% crystalline
yield; see Equation (5). The same compound was already
obtained as one of the products of the reaction between 1
and AgCl in CH3CN. Further experiments with this com-
plex showed it to be stable only in apolar solvents. When it
was dissolved under heat in CH2Cl2, a redox reaction was
initiated to yield the coordination polymer [1(Ag4Cl6)]n –
see Equation (6) – which was already shown to be one of
the products of reaction between 1 and AgCl in CH3CN.
(5)
(6)
Properties of the One-Dimensional Polymers [1(AgX)2]n
(X = Br or I)
The experiments described above showed that coordina-
tion compounds of the neutral guanidines could be ob-
tained by careful choice of the solvent. Whereas [1(AgCl)2]
is a dinuclear compound, [1(AgBr)2]n and [1(AgI)2]n repre-
sent chain polymers. Furthermore, [1(AgCl)2] is highly ame-
nable to redox reactions when brought into contact with
solvents of moderate to strong polarity. In further experi-
ments described in this section, we analyzed the properties
and redox chemistry of the polymers [1(AgBr)2]n and
[1(AgI)2]n. Thermogravimetric (TG) and differential scan-
ning calorimetric (DSC) measurements (see curves in Fig-
ure 8) indicate that both compounds are stable up to tem-
peratures of 250 °C. Their remission spectra (see the Sup-
porting Information) contain broad absorptions below
500 nm. When the compounds were heated to a tempera-
ture of 650 °C, gas evolution was monitored and the materi-
als changed their optical properties dramatically. The ini-
tially yellow colour of the intact polymer turned to black
with a metal-like gleam after the heat treatment (see photos
provided in the Supporting Information). Up to now we
have been unable to characterize the structures of these
products of pyrolysis. The elemental analysis showed them
to contain substantial amounts of carbon and nitrogen.
Further work, which is outside the scope of this article, is
necessary to study the composition and properties of these
materials.
Figure 8. TG and DSC curves (at a heating rate of 10 °Cmin–1
under an N2 atmosphere) for (a) [1(AgBr)2]n and (b) [1(AgI)2]n.
lowing; see Equations (7), (8) and (9). In the case of
reaction of an equimolar mixture of [1(AgBr)2]n and I2 at
room temp. in CH3CN, the coordination polymer
[1(Ag6I8–xBrx)]n with x = 0.7 was isolated in a crystal yield
of 26%. Its structure is depicted in Figure 9 (a). It resembles
that of [1(Ag6I8)]n. In the case of a 2:1 molar ratio of the
two reactants (but otherwise unchanged reaction condi-
tions), a different product was isolated in extremely small
but reproducible yield. This product was unambiguously
identified as the coordination polymer [1(Ag5Br4I3)]n (see
Figure 9, b). The guanidine building blocks are incorpo-
rated into the polymer main chain. The small yield is at
(7)
(8)
(9)
In our oxidation experiments, [1(AgBr)2]n and [1(AgI)2]n
were treated with I2 as well as organic electron acceptors
[2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetra-
chlorobenzoquinone (TCQ) and tetracyanoquinodimethane
(TCNQ)]. The results will be briefly summarized in the fol-
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H.-J. Himmel et al.
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least partially caused by the low solubility of the starting uct that also could be obtained more directly by reaction
reagents. On the other hand, reaction between [1(AgI)2]n between 1 and AgI in MeOH. This compound seems to be
and I2 (0.5 equiv.) yielded not a polymer but the salt of especial stability, as it is obtained under various condi-
1(AgI3) with separated guanidine dicationic and AgI3 dian- tions.
ionic units (see Figure 10).
(10)
(11)
(12)
Figure 9. Fractions of the crystal structures of the coordination
polymers (a) [1(Ag6I8–xBrx)]n with x = 0.7 and (b) [1(Ag5Br4I3)]n.
Figure 11. Structure of the salt 1(DDQ)2. Selected bond lengths
Figure 10. Structure of the salt 1(AgI3). Selected bond lengths [pm]:
Ag–I1 278.48(6), Ag–I2 275.88(6), N1–C1 134.6(2), N1–C4
134.6(2), N2–C4 135.1(3), N3–C4 135.0(2), N4–C2 130.8(2), N4–
C9 136.9(2), N5–C9 134.6(3), N6–C9 133.1(3), C1–C2 150.1(3),
C1–C3Ј 137.5(3), C2–C3 142.2(3).
[pm]: cationic guanidine units: N1–C1 130.4(2), N1–C4 137.4(2),
N2–C4 134.1(2), N3–C4 133.7(2), N4–C2 135.9(2), N4–C9
133.7(2), N5–C9 135.3(2), N6–C9 135.3(2), C1–C2 150.0(3), C1–
C3Ј 143.2(3), C2–C3 136.6(3); anionic DDQ units: O1–C18
124.4(2), O2–C15 124.7(2), Cl1–C14 172.3(2), Cl2–C19 172.5(2),
N8–C21 114.3(3), C17–C21 143.3(3), C14–C15 147.6(3), C14–C19
135.3(3), C15–C16 144.4(3), C16–C17 139.1(3), C17–C18 145.0(3),
C18–C19 146.6(3).
Treatment of [1(AgBr)2]n or [1(AgBr)2]n with the organic
electron acceptor DDQ (2 equiv.) gave a black product,
which was identified as the donor–acceptor couple
1(DDQ)2; see Equation (10). The crystal structure is pro-
vided in Figure 11. Clearly, this compound can be prepared
more directly by reaction between 1 and DDQ. The donor
and acceptor units are arranged in stacks. The packing as
Conclusion
Coordination, redox and polymerization reactions are
well as the black appearance of the material make it attract- either coupled or in competition with each other when the
ive for a future analysis of the electronic properties. Reac- guanidine electron donor 1,2,4,5-tetrakis(tetramethylguan-
tion between [1(AgI)2]n and TCQ or TCNQ yielded the idino)benzene (1) reacts with silver halides in solvents of
polymer [1(Ag6I8)]n – see Equations (11) and (12) – a prod- different polarities. By choice of solvent, the reaction could
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Guanidine Electron Donors and Silver Halides
N 23.65. 1H NMR (400 MHz, CD3CN): δ = 2.88 (48 H, CH3), 5.16
(2 H, ArH) ppm. 13C NMR (100 MHz, CD3CN): δ = 41.48 (CH3),
be directed into the desired channel. The results of this
work are of special importance for the use of guanidine
electron donors as building blocks in coordination poly-
mers. In these polymers, the guanidine units are generally
highly oxidized and coloured, thus making them attractive
for optical and/or electronic applications. This article shows
how halide clusters of different sizes could be incorporated
into the chain polymers, thereby opening an access route to
well-defined arrays of photoactive silver halide clusters. As
103.90, 157.75, 168.07 ppm. IR (CsI): ν = 2946, 1608, 1583, 1564,
˜
1505, 1468, 1420, 1390, 1301, 1253, 1227, 1190, 1164, 1142, 1057,
1016, 898, 879, 838, 749, 683, 620, 538 cm–1. UV/Vis (CH3CN, c =
6.2ϫ10–5 molL–1): λ (ε in Lmol–1 cm–1) = 218 (59431), 293 (16179),
426 (27073), 589 (614) nm. MS-ESI+: m/z (%) = 265.3 (100) [1]2+
,
530.3 (7) [1]+, 611.0 (7) [1 + Br]+. Crystal data for (1)Br2·4MeOH:
C30H66Br2N12O4, Mr = 818.76, 0.30ϫ0.20ϫ0.20 mm3, mono-
clinic, space group P21/n, a = 9.4670(19) Å, b = 15.321(3) Å, c =
shown for the pairs of compounds [1(Ag6I8)·2DMF]n and 14.612(3) Å, β = 104.29(3), V = 2053.8(7) Å3, Z = 2, dcalcd.
=
1.324 Mgm–3, Mo-Kα radiation (graphite-monochromated, λ =
0.71073 Å), T = 100 K, θrange 2.33 to 32.05°. Reflections measd.
14235, indep. 7130, Rint = 0.0366. Final R indices [IϾ2σ(I)]: R1 =
0.0374, wR2 = 0.0803.
[1(Ag6I8)]n as well as [1(Ag4Cl6)·4CHCl3]n and [1(Ag4Cl6)·
2CH2Cl2]n, the incorporation of solvent molecules leads to
significant changes in the polymer structures.
Compound [1(Ag6I8)]n: AgI (221 mg, 0.942 mmol) was added to a
solution of 1 (100 mg, 0.188 mmol) in MeOH (12 mL). The solu-
tion was stirred for a period of 16 h at room temp., during which
time the formation of brown-red solid was observed. Then the reac-
tion mixture was filtered and the product dried under vacuum;
yield 212 mg (0.097 mmol, 51%). Crystals suitable for XRD were
grown from concentrated DMF solutions. Compound [1(Ag6I8)]·
2DMF: C32H64Ag6I8N14O2 (2339.39): calcd. C 16.43, H 2.76, N
8.38; found C 16.78, H 2.60, N 8.22. 1H NMR (400 MHz,
[D6]DMF): δ = 3.01 (48 H, CH3), 5.35 (2 H, ArH) ppm. Low solu-
Experimental Section
General: The synthetic work was carried out under an inert-gas
atmosphere by using standard Schlenk techniques. All solvents
were dried rigorously prior to their use. UV/Vis spectra were re-
corded with a Varian Cary 5000 spectrometer. NMR spectra were
measured with a Bruker Avance II 400 NMR machine. Elemental
analyses were carried out at the Microanalytical Laboratory of the
University of Heidelberg. IR spectra were recorded with a Biorad
Excalibur FTS3000 spectrometer. Thermogravimetric (TG) and
calorimetric (DSC) measurements were carried out with a Mettler
TC15 and DSC30 apparatus under a N2 atmosphere in a tempera-
ture range of 30–600 °C. The heating rate was varied between 2
and 10 °Cmin–1.
bility hampered the 13C NMR spectra. IR (CsI): ν = 2921, 1677,
˜
1661, 1609, 1577, 1561, 1508, 1492, 1460, 1400, 1384, 1320, 1263,
1231, 1167, 1090, 1022, 897, 813, 785, 737, 701 cm–1. UV/Vis
(CH3CN, c = 7.9ϫ10–6 molL–1): λ (ε in Lmol–1 cm–1) = 245 (6827),
285 (1827), 426 (2431) nm. MS-FAB+: m/z (%) = 531.7 (20) [1 +
H]+, 746.5 (1) [1 + 2Ag]+, 784 (2) [1 + 2I]+, 871.0 (7) [1 +
2Ag+I]+, 891.8 (5) [1 + Ag + 2I]+, 978.6 (3) [1 + 3Ag+I]+, 1063.3
Compound (1)Cl2: AgCl (135 mg, 0.934 mmol) was added to a solu-
tion of 1 (100 mg, 0.188 mmol) in CH3OH (10 mL). The solution
was stirred at room temp. for a period of 2 h, during which time
the solution quickly adopted a deep green colour. After filtration,
4/5 of the solvent volume was removed, and the initial amount of
solvent was restored by the addition of Et2O. A dark crystalline
powder of (1)Cl2 precipitated; yield 80 mg (0.133 mmol, 70%). Sin-
gle crystals suitable for XRD were obtained from CH3CN/Et2O.
C28H58Cl2N12O2 [M + 2MeOH] (665.75): calcd. C 50.51, H 8.78,
N 25.25; found C 49.73, H 8.71, N 25.85. 1H NMR (400 MHz,
CD2Cl2): δ = 2.76 (48 H, CH3), 5.44 (2 H, ArH) ppm. 13C NMR
(100 MHz, CD2Cl2): δ = 40.2 (CH3), 111.6, 135.5, 162.7 ppm. IR
(1) [1
+ 5Ag –
H]+. Crystal data for [1(Ag6I8)]·2DMF:
C16H32Ag3I4N7O, Mr = 1169.70, 0.10ϫ0.10ϫ0.10 mm3, mono-
clinic, space group P21/n, a = 11.727(2) Å, b = 19.456(4) Å, c =
12.991(3) Å, β = 94.21(3)°, V = 2956.0(10) Å3, Z = 4, dcalcd.
=
2.628 Mgm–3, Mo-Kα radiation (graphite-monochromated, λ =
0.71073 Å), T = 100 K, θrange 2.09 to 30.02°. Reflections measd.
16815, indep. 8624, Rint = 0.0600. Final R indices [IϾ2σ(I)]: R1 =
0.0442, wR2 = 0.0781. Crystal data for [1(Ag6I8)]: C13H25Ag3I4N6,
Mr = 1096.6, 0.15ϫ0.10ϫ0.10 mm3, monoclinic, space group C2/
c, a = 13.795(3) Å, b = 14.615(3) Å, c = 25.803(5) Å, β = 104.82(3)°,
V = 5029.2(19) Å3, Z = 8, dcalcd. = 2.897 Mgm–3, Mo-Kα radiation
(graphite-monochromated, λ = 0.71073 Å), T = 100 K, θrange 2.36
to 28.03°. Reflections measd. 24142, indep. 5969, Rint = 0.0516.
Final R indices [IϾ2σ(I)]: R1 = 0.0397, wR2 = 0.0972.
(CsI): ν = 2947, 1608, 1564, 1508, 1467, 1421, 1395, 1304, 1256,
˜
1226, 1187, 1165, 1139, 1057, 1018, 896, 840, 806, 749, 688, 623,
532, 458 cm–1. UV/Vis (CH3CN, c = 3.4ϫ10–5 molL–1): λ (ε in
Lmol–1 cm–1) = 218 (42148), 293 (16240), 425 (24148) nm. MS-
ESI+ (MeOH): m/z (%) = 265.3 (100) [1]2+, 530.3 (56) [1]+, 565.6
(25) [1 + Cl]+. Crystal data for (1)Cl2, C26H50Cl2N12: Mr = 601.68,
0.30ϫ0.11ϫ0.05 mm3, orthorhombic, space group Pca2(1), a =
19.210(4) Å, b = 7.5353(15) Å, c = 21.463(4) Å, V = 3106.8(11) Å3,
Z = 4, dcalcd. = 1.286 Mgm–3, Mo-Kα radiation (graphite-mono-
chromated, λ = 0.71073 Å), T = 100 K, θrange 1.90 to 30.58°. Reflec-
tions measd. 75068, indep. 9521, Rint = 0.0644. Final R indices
[IϾ2σ(I)]: R1 = 0.0430, wR2 = 0.0985.
Compound [1(AgBr)2]n: Compound 1 (500 mg, 0.942 mmol) was
dissolved in CH3CN (10 mL). Subsequently, AgBr (354 mg,
1.884 mmol) was added, and the reaction mixture was heated at
90 °C to reflux for a period of 4 h. Then half of the solvent was
removed under vacuum from the reaction mixture. The reaction
mixture was filtered and washed with a small portion of CH3CN.
The pale yellow product was dried under vacuum to yield 779 mg
(0.860 mmol, 91%) [1(AgBr)2]n. Crystals suitable for an XRD
analysis were obtained from concentrated CH3CN solutions.
C26H50Ag2Br2N12 (906.30): calcd. C 34.46, H 5.56, N 18.55; found
C 34.31, H 5.56, N 18.36. 1H NMR (199.92 MHz, CDCl3): δ =
2.79 (s, 48 H, CH3), 5.38 (s, 2 H, ArH) ppm. 13C NMR
(100.55 MHz, CDCl3): δ = 39.94 (CH3), 110.92, 134.94, 162.10
Compound (1)Br2: AgBr (142 mg, 0.755 mmol) was added to a solu-
tion of 1 (80 mg, 0.151 mmol) in MeOH (10 mL). The solution was
stirred at room temp. for a period of 2 h, during which time the
solution quickly turned deep green. Then the solution was filtered
and the solvent was partially removed to around 2 mL. A dark,
crystalline solid precipitated after the addition of Et2O (restoring
the initial 10 mL volume); yield 71 mg (0.103 mmol, 68%). Crystals
suitable for XRD were grown from MeOH/Et2O. C26H50Br2N12
(690.56): calcd. C 45.22, H 7.30, N 24.34; found C 44.79, H 7.29,
ppm. IR (CsI): ν = 2929 (m), 1515 (s, C=N) , 1382 (s), 1265 (m),
˜
1180 (s), 1063 (m), 1020 (vs), 948 (w), 925 (w), 890 (vs), 867 (s),
776 (m), 712 (m), 573 (m), 426 (w) cm–1. MS-FAB+: m/z (%) =
486.1 (34) [1 – NMe2]+, 531.2 (100) [1 + H]+, 611.2 (2) [1 + Br]+,
Eur. J. Inorg. Chem. 2012, 695–704
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
701

H.-J. Himmel et al.
FULL PAPER
719.3 (0.4) [1
+
Ag
+
Br
+
H]+. UV/Vis (CH3CN,
c
=
Crystal data for [1(Ag4Cl6)]·4CHCl3: C15H27Ag2Cl9N6, Mr =
7.37ϫ10–5 molL–1): λmax (ε in Lmol–1 cm–1) = 218 (5970), 274
826.22, 0.35ϫ0.25ϫ0.25 mm3, monoclinic, space group P21/c, a =
20.956(4) Å, b = 11.688(2) Å, c = 23.445(5) Å, β = 92.82(3)°, V
(4828), 427 (2460) nm. Crystal data for C13H25AgBrN6·2CH3CN:
Mr = 535.28, 0.30ϫ0.30ϫ0.27 mm , triclinic, space group P1, a = = 5735.5(19) Å3, Z = 8, dcalcd. = 1.914 Mgm–3, Mo-Kα radiation
3
¯
9.7380(19) Å, b = 11.180(2) Å, c = 12.081(2) Å, α = 92.93(3)°, β (graphite-monochromated, λ = 0.71073 Å), T = 100 K, θrange 1.95
= 109.48(3)°, γ = 109.87(3)°, V = 1145.9(4) Å3, Z = 2, dcalcd.
=
to 33.11°. Reflections measd. 42828, indep. 21709, Rint = 0.0707.
Final R indices [IϾ2σ(I)]: R1 = 0.0523, wR2 = 0.1190. Crystal data
1.551 Mgm–3, Mo-Kα radiation (graphite-monochromated, λ =
0.71073 Å), T = 100 K, θrange 1.97 to 30.05°. Reflections measd.
11697, indep. 6626, Rint = 0.0292. Final R indices [IϾ2σ(I)]: R1 =
0.0345, wR2 = 0.0838.
for [1(Ag4Cl6)]·2CH2Cl2: C14H27Ag2Cl5N6, Mr
=
672.41,
0.30ϫ0.20ϫ0.20 mm3, monoclinic, space group P21/n,
a
=
13.058(3) Å, b = 11.688(2) Å, c = 15.697(3) Å, β = 107.03(3)°, V =
2290.7(8) Å3, Z = 4, dcalcd. = 1.950 Mgm–3, Mo-Kα radiation
(graphite-monochromated, λ = 0.71073 Å), T = 100 K, θrange 2.50
to 31.14°. Reflections measd. 14081, indep. 7282, Rint = 0.0346.
Final R indices [IϾ2σ(I)]: R1 = 0.0399, wR2 = 0.0987.
Compound [1(AgI)2]n: AgI (442 mg, 1.884 mmol) was added to 1
(500 mg, 0.942 mmol) in CH3CN (10 mL). The pale green reaction
mixture was heated at 90 °C to reflux for a period of 4 h. Then half
of the solvent was removed under vacuum. Subsequently, the hot
reaction mixture was filtered, and the solid residue was washed
with a small quantity of CH3CN. Finally, the pale yellow product
was dried under vacuum to obtain 791 mg of [1(AgI)2]n
(0.791 mmol, 84% yield). Crystals suitable for an XRD analysis
were grown over a period of several weeks from concentrated DMF
solutions. C26H50Ag2I2N12 (1000.30): calcd. C 31.22, H 5.04, N
16.80; found C 31.05, H 4.89, N 16.57. 1H NMR (199.92 MHz,
CDCl3): δ = 2.76 (s, 48 H, CH3), 5.37 (s, 2 H, ArH) ppm. 13C NMR
(100.55 MHz, CDCl3): δ = 40.06 (CH3), 111.41, 136.16, 162.30
Decomposition of [1(Ag4Cl6)]n: Compound [1(Ag4Cl6)]n (43.8 mg)
was dissolved in MeOH (3 mL). Formation of a white precipitate
was observed over a period of several days. The solution was fil-
tered and the pale yellow powder dried under vacuum. It was dis-
solved in aqueous NH3, precipitated upon addition of aqueous
HNO3, and was identified as AgCl. The green filtrate contained
(1)Cl2 (15.9 mg).
Compound [1(AgCl)2]: AgCl (54 mg, 0.377 mmol) was added to a
solution of 1 (100 mg, 0.188 mmol) in toluene (10 mL). The reac-
tion mixture was stirred for 3 h at a temperature of 90 °C, leading
to a white precipitate of [1(AgCl)2]. This precipitate was filtered,
washed with small quantities of toluene and dried; yield 120 mg
(0.147 mmol, 78%). C33H58Ag2Cl2N12 [M + C7H8] (909.54): calcd.
C 43.58, H 6.43, N 18.48; found C 42.96, H 6.38, N 18.31. 1H
NMR (400 MHz, CD2Cl2): δ = 2.76 (48 H, CH3), 5.44 (2 H, ArH)
ppm. 13C NMR (100 MHz, CD2Cl2): δ = 40.2 (CH3), 111.6, 135.5,
ppm. IR (CsI): ν = 2927 (m), 1536 (s, C=N) , 1420 (s), 1383 (s),
˜
1263 (m), 1178 (m), 1064 (m), 1021 (vs), 922 (w), 888 (s), 866 (m),
774 (m), 711 (m), 572 (m), 474 (w), 428 (w) cm–1. MS-FAB+: m/z
(%): 486.4 (25) [1 – NMe2]+, 531.5 (100) [1 + H]+, 637.4 (0.3) [1 +
Ag]+, 659.4 (0.6) [1 + I]+, 765.2 (0.2) [1 + Ag + I]+. UV/Vis
(CH3CN, c = 2.62ϫ10–5 molL–1): λmax (ε in Lmol–1 cm–1) = 225
(28738), 273 (17499), 329 (11595), 378 (9384), 421 (7606) nm.
Crystal data for C13H25AgIN6·2DMF: Mr
=
646.35,
a
162.7 ppm. IR (CsI): ν = 2927, 1546, 1483, 1420, 1386, 1264, 1234,
˜
0.11ϫ0.07ϫ0.03 mm3, monoclinic, space group P21/c,
=
1179, 1144, 1060, 1023, 890, 827, 790, 709, 572 cm–1. UV/Vis
(CH3CN, c = 9.90ϫ10–5 molL–1): λmax (ε in Lmol–1 cm–1) = 218
(18908), 290 (9207), 426 (13793) nm. MS-FAB+: m/z (%) = 531.5
(100) [1 + H]+, 637.3 (12) [1 + Ag]+, 675.3 (5) [1 + Ag + Cl +
H]+, 781.3 (0.6) [1 + 2Ag + Cl]+, 816.2 (0.5) [M]+. Crystal data for
11.754(5) Å, b = 22.070(9) Å, c = 10.787(5) Å, β = 110.644(6)°, V
= 2618.5(19) Å3, Z = 4, dcalcd. = 1.640 Mgm–3, Mo-Kα radiation
(graphite-monochromated, λ = 0.71073 Å), T = 100 K, θrange 2.07
to 32.21°. Reflections measd. 66037, indep. 8826, Rint = 0.0508.
Final R indices [IϾ2σ(I)]: R1 = 0.0283, wR2 = 0.0556.
[1(AgCl)2]·C7H8:
C33H57Ag2Cl2N12,
Mr
=
908.55,
0.25ϫ0.20ϫ0.10 mm3, monoclinic, space group P21/c,
a
=
Compound [1(Ag4Cl6)]n: AgCl (270 mg, 1.88 mmol) was added to a
solution of 1 (200 mg, 0.377 mmol) in CH3CN (12 mL). The deep
green solution was stirred at room temp. for a period of 3 h. Sub-
sequently, the solvent was removed under vacuum and the residue
was redissolved in CHCl3 (ϽM;Ͼ30 mL). The dinuclear coordina-
tion compound [1(AgCl)2] precipitated after approximately 1 h at
4 °C and was separated by filtration; yield 70 mg (0.086 mmol,
23%). The filtrate was kept at room temp. for several days until
complete evaporation of the CHCl3 solvent, during which time
brown-red crystals of [1(Ag4Cl6)]n were formed. This product was
washed several times with CH2Cl2; yield 133 mg (0.08 mmol, 21%).
The third product, (1)Cl2, dissolved in the CH2Cl2 phases. The
solution was stored for 24 h at a temperature of 4 °C. Dark green
crystals of (1)Cl2 formed (25 mg, 0.042 mmol, 11%). Analysis for
[1(Ag4Cl6)]n: C30H54Ag4Cl18N12 (1652.45): calcd. C 21.81, H 3.29,
N 10.17; found C 21.99, H 3.32, N 10.26. 1H NMR (400 MHz,
CDCl3): δ = 3.18 (s, 48 H, CH3), 5.00 (s, 2 H, ArH) ppm. Due to
low solubility in CDCl3 and decomposition in other solvents (see
discussion), it proved impossible to obtain reliable 13C NMR spec-
13.428(3) Å, b = 7.3260(15) Å, c = 21.555(4) Å, β = 107.64(3)°, V
= 2020.7(7) Å3, Z = 2, dcalcd. = 1.493 Mgm–3, Mo-Kα radiation
(graphite-monochromated, λ = 0.71073 Å), T = 100 K, θrange 2.13
to 27.92°. Reflections measd. 9491, indep. 4811, Rint = 0.0334. Fi-
nal R indices [IϾ2σ(I)]: R1 = 0.0351, wR2 = 0.0793.
Compound [1(AgCl)2] Dissolved in CH2Cl2: Compound [1(AgCl)2]
(60 mg) was dissolved in CH2Cl2 (10 mL) and heated to 40 °C for
several minutes. The solution turned green and formation of pre-
cipitate was observed. The solution was filtered and concentrated.
Crystals of [1(Ag4Cl6)]n formed over a period of several days. For
analytical data, see above.
Oxidation Experiments with [1(AgBr)2]n and [1(AgI)2]n
[1(Ag6I8–xBrx)]n (x = 0.7): I2 (28 mg, 0.110 mmol) was added to a
solution of [1(AgBr)2]n (100 mg, 0.110 mmol) in CH3CN (12 mL).
The dark yellow reaction mixture was stirred at room temp. for a
period of 2 h. The product precipitated over the course of the reac-
tion as a black powder. The reaction mixture was filtered, the prod-
uct washed twice with CH3CN and dried under vacuum to yield
62 mg (0.027 mmol, 26%). Crystals of the polymer
[1(Ag6I8–xBrx)]n (x = 0.7) suitable for an XRD analysis were ob-
troscopic data for this product. IR (CsI): ν = 2929, 1609, 1524,
˜
1494, 1468, 1395, 1324, 1307, 1263, 1227, 1170, 1139, 1062, 1022,
898, 780, 738, 694, 595 cm–1. UV/Vis (CH3CN,
c
=
3.2ϫ10–5 molL–1): λmax (ε in Lmol–1 cm–1): 217 (47535), 293 tained from CH3CN/Et2O or concentrated DMF solutions.
(18150), 425 (28900) nm. MS-ESI+ (MeOH): m/z = 265.3 (100)
C29H57Ag6Br0.7 7.3N13O1 [M + DMF] (2233.4): calcd. C 15.60, H
[1]2+, 319.0 (2) [1 + Ag]2+, 408.2 (1) [1 + 2Ag + 2Cl]2+, 530.3 (30) 2.57, N 8.15; found C 15.85, H 2.44, N 8.30. H NMR (400 MHz,
[1]+. MS-FAB+: m/z (%) 531.7 (100) [1 + H]+, 638.1 (8) [1 + Ag]+.
[D6]DMSO): δ = 3.08 (48 H, CH3), 5.17 (2 H, ArH) ppm. Low
I
1
702
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 695–704

Guanidine Electron Donors and Silver Halides
solubility hampered the 13C NMR spectra. IR (CsI): ν = 2963,
to 33.12°. Reflections measd. 13682, indep. 6934, Rint = 0.0239.
Final R indices [IϾ2σ(I)]: R1 = 0.0278, wR2 = 0.0590.
˜
1669, 1615, 1528, 1492, 1465, 1393, 1324, 1303, 1263, 1169, 1095,
1025, 801, 696, 602 cm–1. MS-FAB+: m/z (%) = 530.4 (100) [1]+,
609.2 (42) [1 + Br]+, 970.1 (5) [1 + Ag + Br + 2I]+. UV/Vis
(CH3CN, c = 2.30ϫ10–6 molL–1): λmax (ε in Lmol–1 cm–1) = 220
(27142), 245 (13434), 286 (13434), 427 (5277) nm. Crystal data for
Compound 1(DDQ)2: From treatment of [1(AgBr)2]n with 2 equiv.
DDQ: DDQ (50 mg, 0.220 mmol) was added to a solution of
[1(AgBr)2] (100 mg, 0.110 mmol) in CHCl3 (12 mL). The brown-
red reaction mixture was stirred at room temp. for a period of 2 h.
Then the solvent was removed under vacuum and the crude prod-
uct redissolved in acetone (20 mL). By cooling the acetone solution
to 4 °C, 1(DDQ)2 (73 mg) was obtained the next day as black crys-
talline solid (0.074 mmol, 67%). Crystals suitable for an XRD
analysis were obtained from CH3CN/Et2O. C42H50Cl4N16O4
(984.76): calcd. C 51.23, H 5.12, N 22.76; found C 51.02, H 5.12,
N 22.08. 1H NMR (400 MHz, CD2Cl2): δ = 3.07 (48 H, CH3), 5.17
(2 H, ArH) ppm. 13C NMR (100 MHz, CD3CN): δ = 41.75, 104.69,
C26H50Ag6Br0.7 7.3
noclinic, space group C2/c, a = 13.695(3) Å, b = 14.591(3) Å, c =
25.807(5) Å, β = 104.85(3)°, V = 4984.6(17) Å3, Z = 4, dcalcd.
I
N12: Mr = 2160.31, 0.30ϫ0.20ϫ0.20 mm3, mo-
=
2.879 Mgm–3, Mo-Kα radiation (graphite-monochromated, λ =
0.71073 Å), T = 100 K, θrange 2.08 to 30.09°. Reflections measd.
35968, indep. 7226, Rint = 0.0582. Final R indices [IϾ2σ(I)]: R1 =
0.0571, wR2 = 0.1654.
Compound [1(Ag5Br4I3)]n: I2 (14 mg, 0.055 mmol) was added to a
suspension of [1(AgBr)2]n (100 mg, 0.110 mmol) in CH3CN
(12 mL). The reaction mixture was stirred at room temp. for a
period of 2 h. The product (1.2 mg, 0.6 μmol, 1%) was crystallized
from the reaction mixture. The white precipitate in the suspension
was identified as starting reagent. C32H64Ag5Br4I3N14O2 [M +
2DMF] (1916.61): calcd. C 20.05, H 3.37, N 10.23; found C 21.03,
157.61, 168.03 ppm. IR (CsI): ν = 2943, 2214, 1653, 1625, 1559,
˜
1512, 1468, 1402, 1316, 1287, 1230, 1191, 1170, 1143, 1066, 1018,
886, 787, 753, 713, 516, 476 cm–1. UV/Vis (CH3CN,
c =
4.69ϫ10–5 molL–1): λmax (ε in Lmol–1 cm–1) = 222 (21411), 301
(8228), 415 (4524) nm. MS-FAB+: m/z (%) 530.5 (100) [1]+, 758.6
(8) [1 + DDQ]+. MS-FAB–: m/z (%) 228.1 (100) [DDQ]–. Crystal
data for 1(DDQ)2·2CH3CN: C46N56Cl4N18O4, Mr = 1066.89,
1
H 3.33, N 10.08. H NMR (400 MHz, [D6]DMSO): δ = 2.86 (s, 48
3
¯
0.40ϫ0.40ϫ0.35 mm , triclinic, space group P1, a = 7.7080(15) Å,
H, CH3), 5.13 (s, 2 H, ArH) ppm. Low solubility hampered the 13
C
b = 12.654(3) Å, c = 13.100(3) Å, α = 94.95(3)°, β = 97.28(3)°, γ =
92.23(3)°, V = 1261.1(5) Å3, Z = 1, dcalcd. = 1.405 Mgm–3, Mo-Kα
radiation (graphite-monochromated, λ = 0.71073 Å), T = 100 K,
NMR spectroscopic studies. IR (CsI): ν = 2927, 1611, 1528, 1492,
˜
1460, 1395, 1324, 1303, 1229, 1172, 1144, 1066, 1025, 896, 805,
782, 741, 696 cm–1. UV/Vis (CH3CN, c = 9.03ϫ10–6 molL–1): λmax
(ε in Lmol–1 cm–1) = 213 (7453), 293 (1432), 425 (2169) nm. MS-
ESI+ (MeOH/CH3CN): m/z (%) = 265.3 (100) [1]2+, 530.3 (45)
[1]+, 610.1 (6.9) [1 + H + Br]+, 689.1 (2) [1 + H + 2Br]+, 1398.7
(1) [1 + H + 5Ag + Br + 2I]+, MS-ESI– (MeOH/CH3CN): m/z (%)
= 156.1 (32) [Ag + Br + I]–, 863.2 (7) [1 + 2I + Br]–. Crystal data
for C28H53Ag5Br4I3N13: Mr = 1811.49, 0.25ϫ0.18ϫ0.18 mm3, tri-
θrange 2.36 to 30.00°. Reflections measd. 13426, indep. 7291, Rint
0.0549. Final R indices [IϾ2σ(I)]: R1 = 0.0504, wR2 = 0.1077.
=
Compound 1(DDQ)2: From treatment of [1(AgI)2]n with 2 equiv.
DDQ: The procedure was similar to the one described above. Com-
pound [1(AgI)2]n (100 mg, 0.100 mmol) and DDQ (45 mg,
0.200 mmol) were used; yield 63 mg (0.064 mmol; 64%). For analy-
sis, see above.
¯
clinic, space group P1, a = 10.154(2) Å, b = 12.962(3) Å, c =
20.173(4) Å, α = 91.13(3)°, β = 101.84(3)°, γ = 109.83(3)°, V =
2433.0(11) Å3, Z = 2, dcalcd. = 2.473 Mgm–3, Mo-Kα radiation
(graphite-monochromated, λ = 0.71073 Å), T = 100 K, θrange 2.06
to 29.99°. Reflections measd. 25403, indep. 13998, Rint = 0.0429.
Final R indices [IϾ2σ(I)]: R1 = 0.0525, wR2 = 0.1264.
Compound [1(Ag6I8)]n: From treatment of [1(AgI)2]n with 1 equiv.
TCQ: TCQ (24.5 mg, 0.100 mmol) was added to a suspension of
[1(AgI)2]n (100 mg, 0.100 mmol) in CH3CN (12 mL). Then the re-
action mixture was stirred at room temp. for a period of 2 h. After
filtration the precipitate was washed twice with CH3CN and dried
under vacuum to yield 65 mg of product (0.030 mmol, 30%). Crys-
tals were grown from the reaction mixture or concentrated DMF
solutions. C26H50Ag6I8N12 (2193.20): calcd. C 14.24, H 2.30, N
7.66; found C 14.79, H 2.42, N 7.81. Further analysis see above.
Compound 1(AgI3): I2 (26.6 mg, 0.105 mmol) was added to a sus-
pension of [1(AgI)2]n (210 mg, 0.21 mmol) in CH3CN (12 mL). The
reaction mixture was stirred at room temp. for a period of 2 h.
Then the reaction mixture was filtered, the solvent removed under
vacuum, and the residue redissolved in CHCl3 (ϽM;Ͼ10 mL) and
filtered. The concentrated solution was kept at 4 °C overnight,
while brown crystals of 1(AgI3)·2CHCl3 formed; yield 29 mg
(0.023 mmol, 11%). Crystals suitable for an XRD analysis were
obtained from concentrated CH3CN solution. C28H52AgCl6I3N12
(1258.09): calcd. C 26.73, H 4.17, N 13.36; found C 26.98, H 4.27,
N 14.40. 1H NMR (400 MHz, CD3CN): δ = 2.88 (48 H, CH3), 5.16
(2 H, ArH) ppm. 13C NMR (100 MHz, CD3CN): δ = 41.46, 103.97,
Compound [1(Ag6I8)]n: From treatment of [1(AgI)2]n with 2 equiv.
TCNQ: TCNQ (16.3 mg, 0.80 mmol) was added to a suspension of
[1(AgI)2]n (40 mg, 0.040 mmol) in CH3CN (12 mL). Then the reac-
tion mixture was stirred at room temp. for a period of 2 h. After
filtration the precipitate was washed twice with CH3CN and dried
under vacuum to yield 14 mg of product (0.06 mmol, 16%). Crys-
tals were grown from reaction mixture or concentrated DMF solu-
tion. For analysis, see above.
157.66, 168.04 ppm. IR (CsI): ν = 2933, 1602, 1529, 1496, 1465,
˜
1424, 1396, 1380, 1307, 1263, 1231, 1159, 1070, 1018, 898, 882,
X-ray Crystallographic Study: Suitable crystals were taken directly
845, 813, 781, 757, 737, 685, 620, 584, 540, 516, 452 cm–1. UV/Vis out of the mother liquor, immersed in perfluorinated polyether oil
(CH3CN, c = 1.2ϫ10–5 molL–1): λmax (ε in Lmol–1 cm–1) = 209
and fixed on top of a glass capillary. Measurements were made
with a Nonius-Kappa CCD diffractometer with low-temperature
(25981), 245 (18053), 293 (6127), 426 (10216) nm. MS-ESI+
(CH3CN): m/z (%) = 265.3 (100) [1]2+, 328.2 (13) [1 + I]2+, 530. 3 unit using graphite-monochromated Mo-Kα radiation. The tem-
(16.9) [1]+, 657.2 (3) [1 + I]+, 891.1 (5) [1 + AgI2]+, 1018.8 (1) [1 +
perature was set to 100 K. The data collected were processed with
AgI3]+. MS-ESI– (CH3CN): m/z (%) = 361.7 (100) [Ag + 2I]–, 489.0 the standard Nonius software.[17] All calculations were performed
(1) [Ag + 3I + H]–. Crystal data for C26H50AgI3N12: Mr = 1019.35, with the SHELXT-PLUS software package. Structures were solved
0.45ϫ0.40ϫ0.40 mm3, monoclinic, space group C2/c,
13.729(3) Å, b = 14.841(3) Å, c = 17.986(4) Å, β = 94.13(3)°, V
a
=
by direct methods with the SHELXS-97 program and refined with
the SHELXL-97 program.[18,19] Graphical handling of the struc-
= 3655.2(13) Å3, Z = 4, dcalcd. = 1.852 Mgm–3, Mo-Kα radiation tural data during solution and refinement was performed with
(graphite-monochromated, λ = 0.71073 Å), T = 100 K, θrange 2.27
XPMA.[20] Atomic coordinates and anisotropic thermal parameters
Eur. J. Inorg. Chem. 2012, 695–704
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
703

H.-J. Himmel et al.
FULL PAPER
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calculations.
CCDC-844519 [for (1)Cl2], -844518 [for (1)Br2·4MeOH], -844824
[for 1(Ag6I8)]n, -844522 [for 1(Ag6I8)·2DMF]n, -844514 [for
1(AgBr)2·4CH3CN]n, -844524 [for 1(AgI)2·4DMF]n, -844523 [for
1(Ag4Cl6)·4CHCl3]n, -844520 [for 1(Ag4Cl6)·2CH2Cl2]n, -844521
[for 1(AgCl)2]·C7H8, -844525 {for [1(Ag6I8–xBrx)]n (x = 0.7)},
-844517 [for 1(Ag5Br4I3)]n, -844515 [for 1(AgI3)] and -844516
[for 1(DDQ)2·2CH3CN] contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
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[1(AgBr)2]n before and after heating to a temperature of 650 °C.
Acknowledgments
The authors gratefully acknowledge continuous financial support
by the Deutsche Forschungsgemeinschaft (DFG).
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Received: September 15, 2011
Published Online: December 21, 2011
704
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 695–704