Silver(I) coordination polymers containing heteroditopic ureidopyridine ligands: The role of ligand isomerism, hydrogen bonding, and stacking interactions

Article abstract of DOI:10.1021/ic050278y

New silver (I) coordination polymers has been successfully designed and synthesized using heteroditopic ureidopyridine ligands 1 and 2 via a combination of coordinations bonds, hydrogen bonding, and π-π stacking interactions. This study shows an example of the orientation of the pyridine nitrogen relative to the urea moiety (4-substituted, 1, or 3-substituted, 2), used to control the packing of resulting crystalline coordination polymers. The ureidopyridine ligands present some flexibility because of the conformational rotation around the central urea moiety. The co-complexation of the silver(I) cation by two pyridine moieties and of the PF₆^- counteranion by the urea moiety results in the formation of discrete [1₂Ag] ⁺PF₆^-, (3) and [2₂Ag] ⁺PF₆^-, (4) complexes presenting restricted rotation around the central urea functionality. The geometrical information contained in the structures of ligands 1 and 2 and the heteroditopic complexation of silver hexafluorophosphate are fully exploited in an independent manner resulting in the emergence of quasi-rigidly preorganized linear and angular building blocks of 3 and 4, respectively. Additional π-π stacking contacts involving interactions between the π-donor benzene and the π-acceptor pyridine systems reinforce and direct the self-assembly of the above-described combined structural motifs in the solid state. Accordingly, linear and tubular arrays of π-π stacked architectures are generated in the solid state by synergistic and sequential metal ion complexation, hydrogen bonding, and π-π stacking interactions.

Full text of DOI:10.1021/ic050278y

Inorg. Chem. 2005, 44, 5649−5653
Silver(I) Coordination Polymers Containing Heteroditopic Ureidopyridine
Ligands: The Role of Ligand Isomerism, Hydrogen Bonding, and
Stacking Interactions
Pascal Blondeau, Arie van der Lee, and Mihail Barboiu*
Institut Europe´en des Membranes, IEM-CNRS 5635, Place Euge`ne Bataillon, CC 47,
F-34095 Montpellier, Cedex 5, France
Received February 22, 2005
New silver (I) coordination polymers has been successfully designed and synthesized using heteroditopic
ureidopyridine ligands 1 and 2 via a combination of coordinations bonds, hydrogen bonding, and π−π stacking
interactions. This study shows an example of the orientation of the pyridine nitrogen relative to the urea moiety
(4-substituted, 1, or 3-substituted, 2), used to control the packing of resulting crystalline coordination polymers. The
ureidopyridine ligands present some flexibility because of the conformational rotation around the central urea moiety.
-
The co-complexation of the silver(I) cation by two pyridine moieties and of the PF6 counteranion by the urea
moiety results in the formation of discrete [12Ag]+PF6-, (3) and [22Ag]+PF6-, (4) complexes presenting restricted
rotation around the central urea functionality. The geometrical information contained in the structures of ligands 1
and 2 and the heteroditopic complexation of silver hexafluorophosphate are fully exploited in an independent manner
resulting in the emergence of quasi-rigidly preorganized linear and angular building blocks of 3 and 4, respectively.
Additional π−π stacking contacts involving interactions between the
π-donor benzene and the π-acceptor pyridine
systems reinforce and direct the self-assembly of the above-described combined structural motifs in the solid state.
Accordingly, linear and tubular arrays of π−π stacked architectures are generated in the solid state by synergistic
and sequential metal ion complexation, hydrogen bonding, and π−π stacking interactions
Introduction
constituents and on the interactions between them.2-4 Among
these interactions, noncovalent motifs such as metal-ligand
coordination,3 hydrogen bonding,4 and π-π stacking5 have
been used for the generation of a wide variety of such
superstructures. In many previous examples, solvent mol-
ecules, anion templates or both were found to produce a
dramatic effect on the extended structure of the network.5,6
One approach to address this problem is to design molecular
ligands built from binding subunits of different types to
Molecular construction in a bottom-up strategy and self-
organization of new coordination polymers are the major
facets of supramolecular chemistry and crystal engineering.1,2
The design and construction of metal-organic coordination
polymers has attracted intense interest not only for their
potential applications as new functional materials but also
for their fascinating structural and superstructural diversity.
Crystal engineering of metal-organic networks via self-
assembly of ligand “spacers” and metal “nodes” has attracted
considerable interest because of the structural diversity in
chemistry or material science. The path from molecular to
large crystalline systems depends both on the nature of its
(3) For recent reviews on metal ion-metal self-assembly, see for
example: (a) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. ReV. 2000,
100, 853-908. (b) Swiegers, G. F.; Malfetese, T. F. Chem. ReV. 2000,
100, 3483-3538. (c) Holliday, B. J.; Mirkin, C. A. Angew. Chem.
2001, 113, 2076-2097; Angew. Chem. Int. Ed. 2001, 40, 2022-2043.
(d) Seidel, S. R.; Stang, P. J. Acc. Chem. Res. 2002, 35, 972-983.
(4) For recent reviews on metal-hydrogen bonding self-assembly, see
for example: (a) Desiraju, G. R. Acc. Chem. Res. 2002, 35, 565-
573. (b) Lehn, J.-M. In Supramolecular Polymers; Ciferi, A., Ed.;
Dekker: New York, 2000, 615-641. (c) Archer, E. A.; Gong, H.;
Krische, M. J. Tetrahedron 2001, 57, 1139-1159.
* To whom correspondence should be addressed. E-mail:
mihai.barboiu@iemm.univ-montp2.fr.
(1) (a) Lehn, J.-M. Supramolecular Chemistry-Concepts and Perspec-
tiVes; VCH: Weinheim, Germany, 1995; 124-138. (b) Lehn, J.-M.
Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 4763-4768.
(2) (a) Special Issue on Molecular Architectures. Acc. Chem Res. 2005,
38, 215-378. (b) Special Issue on Crystal Engineering. J. Chem. Soc.,
Dalton Trans. 2000, 3704-3998.
(5) (a) Schmuck, C. Angew. Chem. 2003, 115, 2552-2556; Angew. Chem.,
Int. Ed. 2003, 42, 2448-2451. (b) Oh, K.; Jeong, K.-S.; Moore, J. S.
Nature 2001, 414, 889-893. (c) Janiak, C. J. Chem. Soc., Dalton
Trans. 2000, 3885-3896.
10.1021/ic050278y CCC: $30.25
Published on Web 07/06/2005
© 2005 American Chemical Society
Inorganic Chemistry, Vol. 44, No. 16, 2005 5649

Blondeau et al.
Figure 1. Concept and design of molecular precursors 1 and 2. Drawings depict compounds 1 and 2 and show the (a) linear and (b) angular ion coordination
directing structure scaffolds, the (c) urea head-to-tail and (d) anion urea hydrogen bonding, and the (e) π-π stacking guiding interactions.
combine within their structures the information required for
the processing of distinct noncovalent interactions leading
to different supramolecular architectures.6 Metal-directed
self-assembly3,6 or combined metal coordination, anion-
hydrogen bonding (templating),7 and π-π stacking-metal
coordination5c,8 interactions have been extensively used as
a powerful tools for the spontaneous generation of such
crystalline coordination superstructures.
Results and Discussions
Design Strategy. The systems mentioned in this paper
operate under conditions in which distinct metal coordination,
hydrogen bonding, and π-π stacking interactions should be
involved in independent binding events between the het-
eroditopic ligands 1 and 2 and AgPF6.
The molecular information contained in the structure of
the heteroditopic ligands 1 and 2 (Figure 1) should be
exploited by the metal ion coordination, urea-self
self-assembly9a or hydrogen bond-anion coordination
(templating)9b,c interactions. Molecular heteroditopic ligands
1 and 2 were designed as precursors for coordination
polymeric materials by combining silver-coordination and
hexafluorophosphate hydrogen bonding events and were
based on three encoded features. (i) The coordination sphere
of silver(I) can adopt coordination numbers between two and
six and various geometries, as a function of the nature of
the used ligand.6 According to the literature, the silver(I)
cation prefers a linear two-coordinate coordination geometry
with N-donor ligands6a generating a variety of discrete square
macrocycles6b,c or 1D, 2D, and 3D coordination polymers,6a,6d-f
as a function of the molecular information stored in the
ligand. Assuming that the ureidopyridine ligands 1 and 2
coordinate to Ag+ cations upon a linear coordination
geometry, their subsequent substitution in para and meta
positions with benzourea groups might be directed by the
subsequent hydrogen bonding events to the linear (Figure
1a) and angular (Figure 1b) coordination polymers. (ii)
Hydrogen bonding guiding interactions could be one of the
following: (a) the urea head-to-tail motif (Figure 1c) which
could generate hydrogen bond ribbons or (b) the anion
assisted self-assembly generating scaffold specific geometries
(Figure 1d) as function of the hydrogen bond geometry of
the resulting anion-urea complex.7 (iii) Additional π-π
stacking contacts involving interactions between the π-donor
benzene and the π-acceptor pyridine systems (Figure 1e)
In this paper we describe new silver (I) coordination
polymers, which are built up through the combination of
silver-coordination, anion-hydrogen bonding, and π-π
stacking interactions. We have designed two heteroditopic
ureidopyridine ligands, 1 and 2, which complex the silver
hexafluorophosphate by using both metal-coordination (py-
ridine) and anion-hydrogen bonding (urea) events (Figure
1). This study shows an example of the orientation of the
pyridine nitrogen relative to the urea moiety (4-substituted,
1, or 3-substituted, 2) used to control the packing of
the resulting crystalline coordination polymers. The self-
-
-
assembly of discrete [12Ag]+PF6 (3) and [22Ag]+PF6 (4)
complexes, in the crystalline coordination polymers, relies
on the use of linear and angular geometries by means of
directional information encoded within the metal and ligand
precursors.
(6) (a) Khlobystov, N. A.; Blake, A.; Champness, N. R.; Lemenovskii,
D. A.; Majouga, A. G.; Zyk, N. V.; Schroder, M. Coord. Chem. ReV.
2001, 222, 155-192 and references therein. (b) Sharma, C. V. K.;
Rogers, R. D. Cryst. Eng. 1998, 1, 19-38. (c) Jung O. S.; Kim Y. J.;
Lee, Y. A.; Kang, S. W.; Choi, S. N. Cryst. Growth Des. 2004, 4,
23-24. (d) Oh, M.; Stern, C. L.; Mirkin, C. A. Inorg. Chem. 2005,
44, 2647-2653. (e) Bosch, E. Inorg. Chem. 2002, 41, 2543-2547.
(f) Sun, D.; Cao, R.; Weng, J.; Hong, M.; Liang, Y. J. Chem. Soc.,
Dalton Trans. 2002, 291-292.
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Noveron, J. C.; Lah, M. S.; del Sesto, R. E.; Arif, A. M.; Miller, J. S.;
Stang, P. S. J. Am. Chem. Soc. 2002, 124, 6613-6625. (c) Uemura,
K.; Kitagawa, S.; Kondo, M.; Fukui, K.; Kitaura, R.; Chang, H. C.;
Mizutani, T. Chem.sEur. J. 2002, 8, 3587-3600. (d) Tadokoro, M.;
Kanno, H.; Kitajiama, T.; Shimada, H.; Nakanishi, N.; Isodobe, K.;
Nakasuji, K. Proc. Natl. Acad. Sci. 2002, 99, 4950-4995. (e) Muthu,
S.; Yip, J. H. K.; Vittal, J. J. J. Chem. Soc., Dalton Trans. 2002, 23,
4561-4568. (f) Hassenknopf, B.; Lehn, J.-M.; Boumediene, N.;
Dupont-Gervais, A.; Van Dorsselaer, A.; Kneisel, B.; Fenske, D. J.
Am. Chem. Soc. 1997, 119, 10956-10962.
(9) (a) Etter, M. C. Acc. Chem. Res. 1990, 23, 120-126. (b) Scheerder,
J.; Duynhoven, J. P. M.; Engbersen, J. F. J.; Reinhoudt, D. N. Angew.
Chem. 1996, 108, 1172-1175; Angew. Chem., Int. Ed. Engl. 1996,
35, 1090-1093. (c) Barboiu, M.; Vaughan, G.; van der Lee, A. Org.
Lett. 2003, 5, 3073-3076.
(8) (a) Barboiu, M.; Vaughan, G.; Kyritsakas, N.; Lehn, J.-M. Chem.s
Eur J. 2003, 9, 763-769. (b) Barboiu, M.; Lehn, J.-M. Proc. Natl.
Acad. Sci. 2002, 99, 5201-5206.
5650 Inorganic Chemistry, Vol. 44, No. 16, 2005

SilWer(I) Coordination Polymers
Figure 2. Crystal structure of silver complexes 3 and 4 indicating (a) a
linear or (b) an angular relative disposition of phenylurea hydrogen bond
directing substituents. The aromatic H atoms are omitted for clarity.
Figure 3. Stick representation of the crystal packing of silver complexes.
They show (a) linear complex 3 and (b) the circular-type architecture of
complex 4. The aromatic H atoms are omitted for clarity.
Figure 4. (a) Crystal packing of the linear supramolecular rods of complex
4. (b) CPK representation along the axis of the stacks, (c) perpendicular
stick representation (the PF6 are shown in CPK), and (d) crystal packing
of the tubular bundles of complex 4. The aromatic H atoms are omitted for
clarity.
might reinforce and direct the self-assembly of above-
described combined structural motifs.8
-
-
Synthesis and Characterization of [12Ag]+PF6 , 3 and
-
[22Ag]+PF6 , 4 Complexes. By following the above-
The Ag+ ions are coordinated by two pyridine units
situated in an almost planar arrangement (average Ag-N
bond length is 2.15 Å), presenting a linear coordination
geometry. Subsequent substitution of pyridine moieties in
the 4 and 3 positions induced a linear or an orthogonal (inner
angle between nitrogen mean lines of about 165° and 85°,
respectively) relative disposition of the phenylurea hydrogen
bond-directing phenylurea moieties.
mentioned strategy, we designed ligands 1 and 2, which we
prepared from phenyl isocyanate and 4- and 3-aminopyridine,
respectively. Complexation studies revealed that the addition
of AgPF6 salt to acetonitrile suspensions of 1 or 2 (1/1, mol/
mol) caused a rapid dissolution of the ligand to give colorless
solutions, the quantitative result of which are complexes 3
and 4. The 1H NMR spectra of the complexes 3 and 4 were
very sharp, indicating the formation of discrete metal
complexes. They showed a deshielding of the pyridine
protons, resulting from the silver complexation, and a
deshielding of the N-H urea protons, resulting from the
anion complexation. The positive electrospray mass spectra
PF6- counteranions were chosen for their strong F‚‚‚H-N
hydrogen bonding and their hydrophobic properties.6 In both
-
3 and 4 monomeric complexes, the PF6 counteranion is
hydrogen bonded to one urea moiety and the F‚‚‚H-N
hydrogen bond lengths fall within the range of 2.04-2.28
Å (Figure 2). This would result in the emergence of quasi-
rigidly preorganized linear and angular building blocks of 3
and 4, respectively.
The urea head-to-tail or anion-template hydrogen bonding
interactions (Figure 1 panels c and d) could in principle yield
a set of interconverting complexes in solution10 and lead to
a preferential expression of a specific member in the solid
state.
of the complexes 3 and 4 showed two peaksat 533.4 (100%)
107
and 535.4 (100%), corresponding to isotopic species [L2
-
Ag]+ and [L2109Ag]+, of an almost equal abundance (L ) 1
or 2).
-
Crystal Structures of Linear [12Ag]+PF6 (3) and
-
Tubular [22Ag]+PF6 (4) Architectures. Crystals of
-
-
[12Ag]+PF6 (3) and [22Ag]+PF6 (4) were obtained from
acetonitrile/isopropyl ether (1/5, vol/vol) solutions at room
temperature. The molecular structure and packing diagrams
are presented in Figures 2-4. The crystal structure of Ag(I)
complexes 3 and 4 revealed that these crystals are based on
linear (Figure 2a) and angular (Figure 2b) elementary
(monomeric) scaffolds.
The two independent hydrogen bonding interactions are
expressed in an independent manner in the structure of
complex 3 (Figure 3a). Both urea moieties of ligand 1 are
connected by head-to-tail hydrogen bonds with one urea
Inorganic Chemistry, Vol. 44, No. 16, 2005 5651

Blondeau et al.
moiety of two neighboring molecules of 1 (average N-H-O
Generally, control over the self-assembly process is achieved
by using a structurally rigid species.14 The heteroditopic
ureidopyridine ligands have some flexibility because of the
conformational rotation around the central urea moiety. The
co-complexation of the silver(I) cation by two pyridine
moieties and the co-complexation of the PF6- counteranion
by the urea moiety results in the formation of discrete
[12Ag]+PF6 (3) and [22Ag]+PF6 (4) complexes with
restricted rotation around the central urea functionality. The
geometrical information contained in the structure of ligands
1 and 2 and the heteroditopic complexation of silver
hexafluorophosphate are fully exploited in a independent way
resulting in the emergence of quasi-rigidly preorganized
linear and angular building blocks of 3 and 4, respectively.
Additional π-π stacking contacts reinforce and direct the
self-assembly of the above-described combined structural
motifs in the solid state. Accordingly, the linear and tubular
arrays of π-π stacked architectures are generated in the solid
state by synergistic and sequential metal ion complexation,
hydrogen bonding, and π-π stacking interactions
distance is 3.01 Å, consistent with other urea systems9) which
-
are each and successively bonded by a PF6 counteranion
-
(Figure 3a). This results the urea-urea-PF6 hydrogen
bonded triads, which developed in a parallel fashion. They
are assisted by favorable π-π stacking interactions between
neighboring π-donor benzene molecules and π-acceptor
pyridine rings (centroid-centroid distance of 3.98 Å, cor-
responding to van der Waals contact).
The solid-state architecture of 3 that resulted from the
combination of these heterocomplexation processes is a linear
coordination polymer with hydrogen bonded anions filling
the voids between the parallel rods (Figure 4a).
-
-
The relative crystal packing of angular complex 4 is
different from that of complex 3 and deserves some com-
ment. In the solid-state structure of 4, the urea-anion
hydrogen bonding is preferred to the urea head-to-tail
interaction and is favored by the relative angular disposition
of the donor urea moieties (Figure 3b). This conformation
allows considerable overlap between all of the aromatic
pyridine-benzene pairs of the neighboring angular mono-
mers of 4 (average π-π stacking centroid-centroid distance
of 3.65 Å, Figure 3b). Accordingly, tubular arrays of π-π
stacked columnar architectures of about 15 Å external
diameter are generated in the solid state (Figure 4 panels
b-d). The synergistic effect of the silver(I) metal-ion
complexation, the anion-hydrogen bond templating, and the
large stacking interactions result in the formation of a
regulated polytubular bundle-type architecture in which the
anions are arranged into an approximately linear array, tightly
fitting into a polar N-H surrounded central cavity of about
8.40 Å diameter. One may point out that the role of the
stacking interaction in the present tubular superstructure is
related to that previously described for organic nanotubes11
or artificial mono12 and double helix supramolecular archi-
tectures.8,13
Experimental Section
General Methods. All reagents were obtained from commercial
suppliers and used without further purification. Acetonitrile was
distilled over CaH2. All organic solutions were routinely dried using
sodium sulfate (Na2SO4). Column chromatography was carried out
on Merck alumina activity II-III.
1H and 13C NMR and COSY and ROESY spectra were recorded
on an ARX 250 MHz Bruker spectrometer in CD3CN. Mass
spectrometric studies were performed using a quadrupole mass
spectrometer (Micromass). The microanalyses were carried out at
Service de Microanalyses, CNRS, Lyon, France.
General Procedure for the Synthesis of Compounds 1 and 2.
Compounds 1 and 2 were prepared by adding phenyl isocyanate to
the corresponding 4- and 3-aminopyridine (1.5/1 mol/mol) in
benzene, and reaction was refluxed under Ar for 5 h. After the
solvent was removed, the residue was subjected to recrystallization
from acetonitrile to produce 1 and 2 as colorless crystals.
Conclusion
In conclusion, new silver(I) coordination polymers have
been successfully designed and synthesized using heterodi-
topic ureidopyridine ligands 1 and 2 via the combination of
silver(I) coordination, hydrogen bonds, and π-π stacking
interactions. Although many coordination polymers2,6 have
been widely studied on the basis of coordination bonds, a
smaller number of examples focus on the combination of
coordination bond and multi-supramolecular interactions.
1-Phenyl-3-pyridine-4-yl-urea (1). Yield: 85%. 1H NMR (CH3-
CN): δ 7.1 (t, J ) 6.95 Hz, 1H, H1), 7.28 (m, 6H, H2 H3, H4), 8.1
(s, 1H, Hb), 8.4 (d, J ) 6.03 Hz, 2H, H5), 8.8 (s, 1H, Ha). 13C
NMR (CDCl3): δ 113.6, 120.7, 124.6, 129.6, 138.0, 147.7, 150.2,
153.0. ES-MS: m/z [M + H+] 214 (100). Anal. Calcd for
C12H11N3O (213.2 g/mol): C, 67.59; H, 5.20; N, 19.71. Found:
C, 67.49; H, 5.33; N, 19.10.
1-Phenyl-3-pyridine-3-yl-urea (2). Yield: 80%. 1H NMR (CH3-
CN): δ 7.1 (t, J ) 6.95 Hz, 1H, H1), 7.26 (m, 6H, H2 H3, H4, H7),
8.2 (s, 1H, Hb), 8.3 (d, J ) 6.03 Hz, 1H, H5), 8.53 (d, J ) 6.03 Hz,
1H, H6), 8.9 (s, 1H, Ha). 13C NMR(CDCl3): δ 120.7, 124.6, 129.6,
(10) In particular, a dynamic library of such hydrogen bond complexes
can be generated from which a preferential expression could be
extracted by crystallization. For example, see: (a) Baxter, P. W. N.;
Lehn, J.-M.; Baum, G.; Fenske, D. Chem.sEur J. 2000, 6, 4510-
4517. (b) Baxter, P. W. N.; Khoury, R. G.; Lehn, J.-M.; Baum, G.;
Fenske, D. Chem.sEur J. 2000, 6, 4140-4148.
(11) Bong, D. T.; Clark, T. D.; Granja, J. R.; Ghadiri, M. R. Angew. Chem.
2001, 113, 1016-1041; Angew. Chem. Int. Ed. 2001, 40, 988-1011
and references therein.
(12) (a) Ohkita, M.; Lehn, J.-M.; Baum, G.; Fenske, D. Chem.sEur J.
1999, 12, 3471-3481. (b) Cuccia, L. A.; Ruiz, E.; Lehn, J.-M.; Homo,
J.-C.; Schmutz, M. Chem.sEur J. 2002, 8, 3448-3457.
(13) (a) Berl, V.; Huc, I.; Khoury, R. G.; Krische, M. J.; Lehn, J.-M. Nature
2000, 407, 720-723. (b) Berl, V.; Huc, I.; Khoury, R. G.; Lehn, J.-
M. Chem.sEur. J. 2001, 7, 2798-2809 and 2810-2820.
(14) (a) Steel, P. J. Acc. Chem. Res. 2005, 38, 243-250. (b) Elsevier, C.
J.; Reedjik, J.; Walton, P. H.; Ward, M. D. J. Chem. Soc., Dalton
Trans. 2003, 1869-1880.
5652 Inorganic Chemistry, Vol. 44, No. 16, 2005

SilWer(I) Coordination Polymers
138.0, 139.4, 147.7, 150.2, 153.0. ES-MS: m/z [M + H+] 214 (100).
Anal. Calcd for C12H11N3O (213.2 g/mol): C, 67.59; H, 5.20; N,
19.71. Found: C, 67.12; H, 5.44; N, 19.80.
(7) Å, b ) 11.7012(8) Å, c ) 12.0765(7) Å, R ) 109.30(1)°, â
)90.750(8)°, γ ) 89.690(9)°, V ) 1278.4(2) Å3; triclinic; space
group P1h; Z ) 2; Fcalcd ) 1.765 gcm-3; µ ) 0.931 mm-1; 23558
measured reflections, 14350 unique, 2794 with I > 2σ(I); final R
factors, R1 ) 0.1186 and R2 ) 0.0759 (R1 ) 0.0347 and R2 )
0.0447 for data I > 2σ(I)); 361 parameters. Maximal residual
X-ray Crystallographic Data for Complexes 3 and 4. X-ray
diffraction data for silver complexes 3 and 4 were collected with
monochromatized Mo KR radiation (λ ) 0.71073 Å) on an Xcalibur
diffractometer (Oxford Diffraction) equipped with a CCD camera.
Data were reduced using the Crysalis RED software. The structures
were determined using direct methods and refined by the full-matrix
least-squares methods (CRYSTALS15). All data were used for the
refinements except for 4 where only data with I > 2σ(I) were used.
Data for the latter compound were particularly weak because of
the size of the selected crystal. Non-hydrogen atoms were refined
electron density: 1.460 eÅ-3
.
-
[22Ag]+PF6 (4). Compound 4 was formed from ligand 2 (3
mg, 14.0 mmol) and AgPF6 (18 mg, 7.0 mmol) in CD3CN at room
1
temperature. H NMR (CH3CN): δ 7.1 (t, J ) 6.95 Hz, 1H, H1),
7.26 (m, 4H, H2, H3), 8.3 (d, J ) 6.03 Hz, 2H), 8.53 (t, J ) 6.03
Hz,1H), 8.73 (d, J ) 6.03 Hz,1H, H2, H3), 8.9 (s, 1H, Ha), 9.2 (s,
1H, H2, Hb). ES-MS: m/z 533.4 (50%) [22107Ag]+, 535.4 (50%)
[22109Ag]+. X-ray crystallographic data: C26H25AgF6N7O2P; crystal
dimensions 0.10 × 0.08 × 0.05 mm; cell dimensions a ) 10.907-
(1) Å, b ) 20.387(1) Å, c ) 13.286(2) Å, R ) 90°, â ) 106.19-
(2)°, γ ) 90°, V ) 2837.1(6) Å3; monoclinic; space group P21/c;
Z ) 4; Fcalcd ) 1.686 gcm-3; µ ) 0.845 mm-1; 53888 measured
reflections, 9604 unique, 716 with I > 2σ(I); final R factors, R1 )
0.1171 and R2 ) 0.1342; 153 parameters. Maximal residual electron
-
anisotropically, except for 4. For this compound, the PF6 coun-
terions were refined as a rigid body. Hydrogen atoms were generally
found using the Fourier difference maps and were allowed to ride
on their parent atoms.
-
[12Ag]+PF6 (3). Compound 3 was formed from ligand 1 (3
mg, 14.0 mmol) and AgPF6 (18 mg, 7.0 mmol) in CD3CN at room
1
density: 1.860 eÅ-3
.
temperature. H NMR (CH3CN): δ 7.1 (t, J ) 6.95 Hz, 1H, H1),
7.26 (m, 4H, H2, H3), 8.1 (t, J ) 6.03 Hz, 1H, H5), 8.3 (d, J )
6.03 Hz, 2H, H4), 8.53 (d, J ) 6.03 Hz, 2H, H6), 8.7 (s, 1H, Hb),
9.1 (s, 1H, Ha). ES-MS: m/z 533.4 (100%) [12107Ag]+, 535.4 (100%)
[12109Ag]+. X-ray crystallographic data: C24H22AgF6N6O2P; crystal
dimensions: 0.40 × 0.20 × 0.09 mm; cell dimensions a ) 9.5870-
Acknowledgment. This research was supported by the
European Science Foundation (EURYI Award 2004), by the
Ministe`re de la Recherche et de la Technologie (ACI Jeunes
Chercheurs) and by the CNRS.
Supporting Information Available: Crystallographic data in
CIF format. This material is available free of charge via the Internet
at http://pubs.acs.org.
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