Coordination networks through the dimensions: From discrete clusters to 1D, 2D, and 3D silver(I) coordination polymers with rigid aliphatic amino ligands

Article abstract of DOI:10.1021/ic049786i

The use of a ligand directed strategy in the assembly of discrete clusters, 1D chains, 2D layers, and 3D networks using aliphatic N-donor ligands has been investigated. The ligands are a family of amines with rigid backbones [cis,cis-1,3,5-triaminocyclohexane (cis-tach), cis,trans-1,3,5- triaminocyclohexane (trans-tach), cis-1,3-diaminocyclohexane (cis-dach), and cis-3,5-diaminopiperidine (cis-dapi)], and their complexation with Ag(I) salts results in a diverse set of architectures with the following compositions: [Ag₃(cis-tach)₂]F₃·4CH ₃OH·0.5H₂O (1), [Ag₃(cis-tach) ₂]-F₃·6H₂O (2), {[Ag(cis-dach)]CIO ₄}_n (3), {[Ag(cis-tach)NO₃}_n (4), {[Ag(trans-tach)]PF₆}_n (5), and {[Ag(cis-dapi)]CF ₃SO₃}_n (6). Structural analysis shows that compounds 1 and 2 are discrete M₃L₂ cage-type clusters with varying solvent molecule content. Short Ag...Ag contacts (3.021(8) A) are observed to dimerize discrete units in compound 2. Compound 3 is a 1D zigzag chain formed by coordination to the two primary amines of cis-dach, whereas the tridentate ligands in compounds 4 and 5 (cis-tach and trans-tach, respectively) are able to form tubular architectures by virtue of their ability to wrap round the channel walls. An infinite 2D coordination network is demonstrated by compound 6, in which the three coplanar amino donors of cis-dapi coordinate to the trigonal planar Ag(I) ions to form a layered structure of 6³ topology. These are compared with a previously reported 3D structure, {[Ag(trans-tach)]NO₃}_n (7), that belongs to this family of architectures.

Full text of DOI:10.1021/ic049786i

Inorg. Chem. 2004, 43, 4953−4961
Coordination Networks through the Dimensions: From Discrete
Clusters to 1D, 2D, and 3D Silver(I) Coordination Polymers with Rigid
Aliphatic Amino Ligands
Alexandra L. Pickering, De-Liang Long, and Leroy Cronin*
Department of Chemistry, Joseph Black Building, UniVersity of Glasgow,
Glasgow G12 8QQ, U.K.
Received February 17, 2004
The use of a ligand directed strategy in the assembly of discrete clusters, 1D chains, 2D layers, and 3D networks
using aliphatic N-donor ligands has been investigated. The ligands are a family of amines with rigid backbones
[cis,cis-1,3,5-triaminocyclohexane (cis-tach), cis,trans-1,3,5-triaminocyclohexane (trans-tach), cis-1,3-diaminocyclo-
hexane (cis-dach), and cis-3,5-diaminopiperidine (cis-dapi)], and their complexation with Ag(I) salts results in a
diverse set of architectures with the following compositions: [Ag (cis-tach)2]F ‚4CH OH‚0.5H O(1), [Ag3(cis-tach)2]-
3
3
3
2
F ‚6H O (2), {[Ag(cis-dach)]ClO }n (3), {[Ag(cis-tach)]NO }n (4), {[Ag(trans-tach)]PF }n (5), and {[Ag(cis-dapi)]-
3
2
4
3
6
CF SO }n (6). Structural analysis shows that compounds 1 and 2 are discrete M L2 cage-type clusters with varying
3
3
3
solvent molecule content. Short Ag‚‚‚Ag contacts (3.021(8) Å) are observed to dimerize discrete units in compound
2. Compound 3 is a 1D zigzag chain formed by coordination to the two primary amines of cis-dach, whereas the
tridentate ligands in compounds 4 and 5 (cis-tach and trans-tach, respectively) are able to form tubular architectures
by virtue of their ability to “wrap” round the channel walls. An infinite 2D coordination network is demonstrated by
compound 6, in which the three coplanar amino donors of cis-dapi coordinate to the trigonal planar Ag(I) ions to
form a layered structure of 63 topology. These are compared with a previously reported 3D structure, {[Ag(trans-
tach)]NO }n (7), that belongs to this family of architectures.
3
Introduction
predictably assemble many intricate architectures, including
two-dimensional polygons and three-dimensional architec-
tures.3 Silver(I) in particular has been used to construct a
great number of geometrically and stereochemically interest-
ing 1D,4 2D,5 and 3D6 infinite networks with coordination
numbers ranging between two and six. To date, a great deal
of emphasis has been placed on the self-assembly of silver-
(I) coordination polymers using multitopic rigid ligands that
possess a considerable degree of preorganization. Many
Much interest currently lies in the field of self-assembled
coordination polymers due to potential application as new
functional solid materials as well as expanding the under-
standing of the assembly processes that underpin the forma-
tion of clusters and multidimensional networks.1 This has
stimulated a great deal of attention towards the design and
construction of polynuclear coordination networks to perform
highly specific and cooperative functions.2 By using well
defined metal and ligand building blocks it is possible to
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2002, 41, 2556. (b) Stang, P. J.; Persky, N. E.; Manna, J. J. Am. Chem.
Soc. 1997, 119, 4777.
* Author to whom correspondence should be addressed. Email:
L.Cronin@chem.gla.ac.uk.
(1) (a) Percec, V.; Glodde, M.; Bera, T. K.; Miura, Y.; Shiyanovskaya,
I.; Singer, K. D.; Balagurusamy, V. S. K.; Heiney, P. A.; Schnell, I.;
Rapp, A.; Spiess, H.-W.; Hudson, S. D.; Duan, H. Nature 2002, 419,
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2003, 125, 8088.
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10.1021/ic049786i CCC: $27.50 © 2004 American Chemical Society
Published on Web 07/08/2004
Inorganic Chemistry, Vol. 43, No. 16, 2004 4953

Pickering et al.
polypyridyl-based ligands such as 4,4′-bipyridyl7 and a more
limited number of highly rigid aliphatic amino ligands such
as hexamethlyenetetramine8 have led to the self-assembly
of low-dimensionality networks such as one-dimensional
systems and tubular frameworks9 as well as high-dimen-
sionality polymers with functional properties.10
on a Bruker DPX-400 (400 MHz 1H). Infrared spectra were
obtained from samples prepared as KBr disks in the 650-4000
cm-1 range using a Jasco FTIR-410 spectrometer. Elemental
analyses were performed on a CE-440 Elemental Analyzer.
Preparation of [Ag3(C6H15N3)2]F3‚4CH3OH‚0.5H2O (1). Silver
fluoride (64 mg, 0.51 mmol) in methanol (2 mL) was added
dropwise to a methanolic solution of cis,cis-1,3,5-triaminocyclo-
hexane (65 mg, 0.51 mmol) and stirred at room temperature for 1
h. The clear, colorless solution was filtered and yielded small
platelike, colorless crystals suitable for diffraction by diffusion with
diethyl ether. Yield 26 mg (0.034 mmol, 6.56%). [Ag3(C6H15N3)2]-
F3‚4CH3OH‚0.5H2O (776.21); found (calc.)%: C 24.93 (24.76),
In this study we report our investigations into the
coordination chemistry of a family of rigid, aliphatic di- and
-
triamino ligands with a range of silver(I) salts (F-, ClO4 ,
-
-
-
NO3 , PF6 , and CF3SO3 ). This study aims to further the
understanding of how the resulting coordination networks
can be manipulated by both engineering degrees of geometric
freedom into the ligand system and by utilizing different
counteranions. In this respect, the four ligands cis,cis-1,3,5-
triaminocyclohexane (cis-tach), cis,trans-1,3,5-triaminocy-
clohexane (trans-tach), cis-1,3-diaminocyclohexane (cis-
dach), and cis-3,5-diaminopiperidine (cis-dapi) are members
of a family of sterically constrained cyclic polyamines. The
rigidity of the six-membered backbone restricts the geometric
freedom of the coordinating nitrogen atoms. However, the
nonplanarity of the ligands and the presence of the primary
aliphatic amino groups facilitate a great deal more torsional
flexibility compared to previously reported rigid ligands.4,5
This study also expands and unites our previous investiga-
tions into silver(I) coordination networks with aliphatic amino
ligands.11,12 Thus we present six new architectures, assembled
using rigid aliphatic amino ligands, that span diverse
architectures from discrete molecules ([Ag3(cis-tach)2]F3.4CH3-
OH‚0.5H2O (1) and [Ag3(cis-tach)2]F3‚6H2O (2)) to one-
([Ag(cis-dach)]ClO4 (3), [Ag(cis-tach)]NO3 (4), and [Ag-
(trans-tach)]PF6 (5)) and two-dimensional coordination
polymers ([Ag(cis-dapi)]CF3SO3 (6))sas well as the con-
textual analysis of a previously reported three-dimensional
coordination network, [Ag(trans-tach)]NO3 (7).11
1
H 6.22 (6.10), N 10.54 (10.83); H NMR (D2O, ppm) 0.96 (pq,
3H, J 11.46 Hz), 2.22 (dt, 3H, J 3.91, 11.41 Hz), 3.24 (m, 3H);
FTIR (KBr, cm-1) 3329 (m), 3276 (m), 1583 (m), 1456 (m), 1384
(m), 1267 (s), 1231 (s), 1175 (s), 1029 (s), 950 (m), 927 (m), 815
(w), 759 (w).
Preparation of [Ag3(C6H15N3)2]F3‚6H2O (2). Silver fluoride (25
mg, 0.19 mmol) in methanol (2 mL) was added dropwise to a
methanolic solution of cis,cis-1,3,5-triaminocyclohexane (50 mg,
0.39 mmol) and stirred at room temperature for 1 h. The resulting
light suspension was filtered, and the clear, colorless solution
yielded small platelike, colorless crystals suitable for diffraction
by diffusion with diethyl ether. Yield 80 mg (0.11 mmol, 56%).
[Ag3(C6H15N3)2]F3‚6H2O (747.13); found (calc.)%: C 19.32 (19.29),
1
H 5.34 (5.66), N 11.60 (11.24); H NMR (D2O, ppm) 0.97 (pq,
3H, J 11.50 Hz), 2.22 (dt, 3H, J 3.90, 11.36 Hz), 3.26 (m, 3H);
FTIR (KBr, cm-1) 3329 (m), 3282 (m), 1583 (m), 1456 (m), 1384
(m), 1268 (s), 1228 (s), 1175 (s), 1027 (s), 950 (m), 925 (m), 814
(w), 759 (w).
Preparation of [Ag(C6H14N2)]ClO4 (3). Silver(I) perchlorate (55
mg, 0.26 mmol) in methanol (4 mL) was added dropwise to a
solution of cis-1,3-diaminocyclohexane (60 mg, 0.52 mmol) in
methanol (4 mL). Upon stirring a white precipitate occurs, which
dissolved partially after addition of water (3 mL) to give a very
fine white precipitate. Filtration removed all solid to yield a clear,
colorless solution that yielded crystals suitable for diffraction by
diffusion of diethyl ether. Yield 28 mg (0.08 mmol, 33%). [Ag-
(C6H14N2)]ClO4 (321.51); found (calc.)%: C 21.98 (22.41), H 4.26
(4.38), N 8.51 (8.31); 1H NMR (D2O, ppm) 0.87 (m, 3H), 1.22 (m,
1H), 1.70 (m, 1H), 1.79 (m, 2H), 1.96 (dhep, 1H, J 2.1, 11.67 Hz),
2.62 (tt, 2H, J 3.79, 11.11 Hz); FTIR (KBr, cm-1) 2925 (w), 2854
(w), 2098 (m), 1596 (m), 1452 (s), 1357 (m), 1176 (w).
Experimental Section
Materials and Methods. Ligands cis,cis- and cis,trans-1,3,5-
triaminocyclohexane,13 cis-1,3-diaminocyclohexane,14 and cis-1,3-
diaminopiperidine15 were synthesized according to literature pro-
cedures. All other solvents and reagents were used as bought
without further purification. NMR spectra were measured in D2O
Preparation of [Ag(C6H15N3)]NO3 (4). Silver nitrate (43 mg,
0.25 mmol) in methanol (3 mL) was added dropwise to a methanolic
solution of cis,cis-1,3,5-triaminocyclohexane (65 mg, 0.51 mmol)
and stirred at room temperature for 30 min, during which a white
solid precipitated. Water (6 mL) was added, and the mixture was
stirred at room temperature for a further 30 min. The resulting clear
colorless solution was filtered and yielded colorless block crystals
suitable for diffraction by slow evaporation of mother liquor over
7 months. Yield: 38 mg (0.11 mmol, 51%). [Ag(C6H15N3)]NO3
(299.09); found (calc.)%: C 24.69 (24.09), H 5.44 (5.055), N 18.73
(7) (a) Soma, T.; Yuge, H.; Iwamoto, R. Angew. Chem., Int. Ed. Engl.
1994, 33, 1665. (b) Yaghi, O. M.; Li, H. J. Am. Chem. Soc. 1996,
118, 295. (c)Fujita, M. Chem. Soc. ReV. 1998, 27, 417. (d) Kusukawa,
T.; Fujita, M. Angew. Chem., Int. Ed. 1998, 37, 3142. (e) Leininger,
S.; Olenyuk, B.; Stang, P. J.; Chem. ReV. 2000, 100, 853.
(8) (a) Zheng, S.-L.; Tong, M.-L.; Chen X-M.; Ng, S. W. J. Chem. Soc.,
Dalton Trans. 2002, 360. (b) Carlucci, L.; Ciani, G.; Proserpio, D.
M.; Rizzato, S. J. Solid State Chem. 2000, 152, 211. (c) Tong, M.-L.;
Zheng, S.-L.; Chen X.-M. Chem. Commun. 1999, 561. (d) Carlucci,
L.; Ciani, G.; Proserpio, D. M.; Sironi, A. J. Am. Chem. Soc. 1995,
117, 631.
(9) (a) Orr, G. W.; Barbour, L. J.; Atwood, J. L. Science 1999, 285, 1049.
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2002, 14, 4736.
(10) (a) Zaworotko, M. J. Angew. Chem., Int. Ed. 2000, 39, 3052. (b) Cui,
Y.; Lee, S. J.; Lin, W. J. Am. Chem. Soc. 2003, 125, 6014. (c) Jenson,
P.; Batten, S. R.; Moubaraki, B.; Murray, K. S. J. Chem. Soc., Dalton.
Trans. 2002, 3712.
1
(18.73); H NMR (D2O, ppm) 0.97 (q, 3H, J 11.60 Hz), 2.02 (m,
3H), 2.92 (tt, 3H, J 3.72, 11.84 Hz); FTIR (KBr, cm-1) 3340 (m),
3291 (m), 3241 (m), 3160 (w), 2915 (m), 2852 (w), 1585 (m), 1457
(w), 1376 (s), 1307 (s), 1199 (m), 1130 (m), 1078 (m), 1064 (m),
1041 (s), 946 (m), 917 (m), 898 (m), 865 (w), 854 (w), 823 (m).
(13) Lions, F.; Martin, K. V. J. Am. Chem. Soc. 1957, 79, 15721.
(14) Hewgill, F. R.; Jefferies, P. R. J. Chem. Soc. 1956, 805.
(15) Pauly, J. W.; Sander, J.; Kuppert, D.; Winter, M.; Reiss, G. J.; Zurcher,
F.; Hoffmann, R.; Fassler, T. F.; Hegetschweiler, K. Chem. Eur. J.
2000, 6, 2830.
(11) Seeber, G.; Pickering, A. L.; Long, D.-L.; Cronin, L. Chem. Commun.
2003, 2002.
(12) Pickering, A. L.; Seeber, G.; Long, D.-L.; Cronin, L. Chem. Commun.
2004, 136.
4954 Inorganic Chemistry, Vol. 43, No. 16, 2004

Coordination Networks through the Dimensions
Table 1. Crystallographic Data for 1-6a
1
2
3
4
5
6
empirical formula
fw
C16H47Ag3F3N6O4.5
776.21
C12H43Ag3F3N6O6
747.13
C6H14AgClN2O4
321.51
C6H15AgN4O3
299.09
C6H15AgF6N3P
382.05
C6H13AgF3N3O3S
372.12
cryst system
a (Å)
b (Å)
monoclinic
15.6080(4)
8.0156(2)
22.5902(6)
90
104.514(2)
90
P21/c
2736.001(12)
4
1.884
2.180
150(2)
monoclinic
8.0479(5)
22.5030(13)
14.0842(9)
90
100.999(3)
90
P21/c
2503.8(3)
4
2.006
0.2385
150(2)
monoclinic
6.3452(8)
9.8756(15)
8.4770(12)
90
106.703(8)
90
P21/m
508.78(12)
2
2.099
0.2235
150(2)
monoclinic
8.2530(3)
7.7035(3)
15.8134(4)
90
104.786(2)
90
P21/n
972.08(6)
4
2.044
0.2063
150(2)
triclinic
orthorhombic
11.5983(4)
12.1522(4)
16.3011(5)
90
6.7103(3)
9.2963(4)
9.9428(3)
104.974(2)
100.175(3)
98.015(2)
P-1
578.48(4)
2
2.193
c (Å)
R (deg)
â (deg)
90
90
γ (deg)
space group
Pbca
2297.56(13)
8
2.152
0.1978
V (Å3)
Z value
F
calcd (g/cm3)
µ (cm-1
T (K)
)
0.1942
150(2)
150(2)
no. observations
5361
4129
1063
12126
11790
2628
residuals: R; wR
0.0518; 0.1279
0.0662; 0.1328
0.0352; 0.0667
0.0161; 0.0368
0.0223; 0.0515
0.0461; 0.0695
a R1 ) Σ|Fo| - |Fc|/Σ|Fo|. wR2 ) {Σ[w(Fo - Fc )2]/Σ[w(Fo )2]}1/2
.
2
2
2
Preparation of [Ag(C6H15N3)]PF6 (5). Silver(I) hexafluoro-
phosphate (64 mg, 0.26 mmol) in methanol (4 mL) was added
dropwise to a solution of cis,trans-1,3,5-triaminocyclohexane (65
mg, 0.51 mmol) in methanol (4 mL). The resulting white precipitate
dissolved completely after addition of water (2 mL) to give a clear,
colorless solution. Single crystals suitable for diffraction were grown
by diffusion of diethyl ether. Yield 65 mg (0.17 mmol, 65%). [Ag-
(C6H15N3)]PF6 (382.05); found (calc.)%: C 19.01 (18.89), H 3.97
(3.96), N 11.11 (11.03); 1H NMR (D2O, ppm) 1.08 (q, 1H, J11.71
Hz), 1.31 (td, 2H, J1.97, 12.13 Hz), 1.88 (d, 2H, J12.54 Hz), 2.26
(m, 1H), 3.19 (t, 2H, J11.79), 3.39 (t, 1H, J12.14 Hz); FTIR (KBr,
cm-1) 3249 (m), 3099 (w), 2883 (w), 2360 (m), 1646 (m), 1610
(s), 1556 (s), 1477 (m), 1455 (m), 1436 (s), 1378 (s), 1336 (s),
1311 (m), 1286 (m), 1184 (m), 1112 (m), 1087 (m), 1041 (m),
1004 (m), 946 (m), 887 (w), 827 (s), 759 (w).
Preparation of [Ag(C5H13N3)]CF3SO3 (6). Silver triflate (112
mg, 0.43 mmol) in methanol (5 mL) was added dropwise to a
methanolic solution of cis-3,5-diaminopiperidine (100 mg, 0.87
mmol) and stirred at room temperature for 30 min. The reaction
mixture was concentrated to 2 mL, and the clear yellow solution
yielded crystals suitable for diffraction by diffusion of diethyl ether.
Yield 146 mg (0.57 mmol, 66%). [Ag(C5N3H13)]CF3SO3 (372.12);
found (calc.)%: C 19.99 (19.37), H 3.51 (3.52), N 11.49 (11.29);
1H NMR (D2O, ppm) 1.08 (pq, 1H), 2.13 (pt, 2H), 2.22 (m, 1H),
2.89 (m, 2H), 3.05 (m, 2H); FTIR (KBr, cm-1) 3430 (bs), 3321(s),
2918 (m), 2810 (w), 1603 (s), 1452 (w), 1383 (w), 1257 (vs), 1169
(s), 1099 (m), 1028 (s), 924 (m), 850 (w), 760 (w), 640 (s), 573
(m), 515 (m).
compound 6 in Pbca, as determined by systematic absences in the
intensity data, intensity statistics, and the successful solution and
refinement of the structures. All structures were solved by a
combination of direct methods and difference Fourier syntheses
and refined against F2 by the full-matrix least-squares technique.
Crystal data, data collection parameters, and refinement statistics
for 1-6 are listed in Table 1. Relevant interatomic bond distances
and bond angles for 1-6 are given in Table 2.
Results and Discussion
Ligand Design. The ligands designed for this investigation
are related as aliphatic amines based around a rigid six-
membered backbone containing a cis-1,3-diamino moiety.
Contrary to many of the ligands reported,4,5 these molecules
are preorganized and possess an additional degree of flex-
ibility in the coordination geometry of the amino groups
(Figure 1). The energetically favorable conformer, in which
the two core amino groups are in cis-equatorial positions on
the cyclohexane ring, is maintained in compounds 1-7 as
every amino group of each ligand coordinates to a different
silver(I) ion. The bidentate ligand cis-dach21 represents the
core of each ligand. The rigidity of the cyclohexane backbone
ensures that the cis-1,3-diamino groups are held in the
equatorial position. The coordinating amines therefore form
a bidentate, planar geometry. cis-Dapi15 has, in addition to
the core diamino binding mode, a third coordinating amino
group. The µ-3 donor set is completed by a secondary amine
located within the six-membered backbone. The secondary
amino group has limited coordination flexibility as compared
to the primary amino groups and therefore constructs a
tridentate coordination plane coplanar to the rigid backbone.
cis-Tach22 is a µ-3 ligand with the third, in this case primary,
amino group extended away from the cyclohexane ring. This
confers a significant amount of flexibility as the torsion angle
Single-Crystal Structure Determination. Suitable single crys-
tals of 1-6 were grown and mounted onto the end of a thin glass
fiber using Fomblin oil. X-ray diffraction intensity data were
measured at 150 K on a Nonius Kappa-CCD diffractometer
[λ(Mo-KR) ) 0.7107 Å]. Structure solution and refinement for
1-6 was carried out with SHELXS-9716 and SHELXL-9717 via
WinGX.18 Corrections for incident and diffracted beam absorption
effects were applied using empirical19 or numerical methods.20
Compounds 1 and 2 crystallized in the space group P21/c, compound
3 in P21/n, compound 4 in P21/m, compound 5 in P-1, and
(21) (a) Cham, S. T.; Diakos, C. I.; Ellis, L. T.; Fenton, R. R.; Munk, V.
P.; Messerle, B. A.; Hambley, T. W. J. Chem. Soc., Dalton Trans.
2001, 2769. (b) Marsh, R. E.; Kapon, M.; Hu, S. Z.; Herbstein, F. H.
Acta Crystallogr., Sect. B: Struct. Sci. 2002, 58, 62.
(22) (a) Yang, J. Y.; Shores, M. P.; Sokol, J. J.; Long, J. R. Inorg. Chem.
2003, 42, 1403. (b) Kuppert, D.; Sander, J.; Roth, C.; Worle, M.;
Weyhermuller, T.; Reiss, G. J.; Schilde, U.; Muller, I.; Hegetschweiler,
K. Eur. J. Inorg. Chem. 2001, 2525. (c) Tan, X. S.; Fujii, Y.; Sato,
T.; Nakano, Y.; Yashiro, M. Chem. Commun. 1999, 881.
(16) Sheldrick, G. M. Acta Crystallogr., Sect. A 1998, A46, 467.
(17) Sheldrick, G. M. SHELXL-97. Program for Crystal structure analysis,
University of Go¨ttingen, Germany, 1997.
(18) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(19) Blessing, R. H. Acta Crstallogr. Sect A 1995, 51, 33.
(20) Coppens, P.; Leiserowitz, L.; Rabinovich, D. Acta Crystallogr. 1965,
18, 1035.
Inorganic Chemistry, Vol. 43, No. 16, 2004 4955

Pickering et al.
Table 2. Bond Lengths (Å) and Angles (deg) for 1-6
compound
bond distances
2.136(5)
bond angles
1
Ag(1)-N(1)
Ag(2)-N(2)
Ag(1)-N(4)
Ag(2)-N(5)
2.142(5)
2.127(5)
N(1)-Ag(1)-N(4)
N(2)-Ag(2)-N(5)
N(3)-Ag(3)-N(6)
N(1)-Ag(1)-N(4)
N(2)-Ag(2)-N(5)
N(3)-Ag(3)-N(6)
172.5(2)
174.4(2)
171.9(2)
172.9(3)
171.7(4)
171.5(4)
2.115(5)
2
Ag(1)-Ag(#1)
Ag(1)-N(4)
Ag(2)-N(5)
Ag(3)-N(6)
Ag-N
Ag-N(1)
Ag-N(3)
3.020(19)
2.108(9)
2.148(9)
2.141(9)
2.151(3)
2.166(16)
2.408(16)
Ag(1)-N(1)
Ag(2)-N(2)
Ag(3)-N(3)
2.144(8)
2.123(9)
2.139(9)
3
4
N-Ag-N
180.0(3)
Ag-N(2)
Ag-N(2)
Ag-N(2)
2.161(16)
2.368(2)
2.244(4)
N(1)-Ag-N(2)
N(1)-Ag-N(3)
N(2)-Ag-N(3)
N(1)-Ag-N(2)
N(1)-Ag-N(3)
N(2)-Ag-N(3)
N(1)-Ag-N(2)
N(1)-Ag-N(3)
N(2)-Ag-N(3)
151.77(6)
107.60(6)
100.31(6)
118.09(8)
141.10(8)
100.77(8)
105.77(13)
113.06(14)
140.95(15)
5
6
Ag-N(1)
Ag-N(3)
2.261(2)
2.299(2)
Ag-N(1)
Ag-N(3)
2.390(4)
2.236(4)
ligands and three crystallographically independent Ag(I) ions
[Ag(1), (2), and (3)] as well as three fluoride counterions,
four methanol solvent molecules, and half a water molecule.
The asymmetric unit of 2 consists of two cis-tach ligands
and three crystallographically independent Ag(I) ions [Ag-
(1), (2), and (3)] as well as three fluoride counterions and
six molecules. Each cylindrical cage structure is formed by
three Ag(I) ions connecting two capping cis-tach molecules
in eclipsed conformation when viewed along the N-Ag-N
vector. Twelve-membered macrocycles form each of the
three faces of the cage and the linear coordination of Ag(2)
in 1 and Ag(1) in 2 is distorted slightly toward the
neighboring unit. The two closest Ag(2) atoms in 1 are
separated by 4.389 Å and hence do not interact. However,
the two closest Ag(1) ions in 2 are positioned to give a short
intermolecular Ag‚‚‚Ag contact (3.021(18) Å). This contact
occurs exclusively between Ag(1)‚‚‚Ag(#1) ions, thus no
polymeric species is formed. This has been investigated by
preliminary DFT calculations which do indicate significant
overlap and bonding interactions. Furthermore a survey of
short Ag‚‚‚Ag interactions in the CSD database demonstrates
that the observed distance is exactly as expected.24 Although
generally longer than ligand-supported metal pairs, direct
metal-metal contacts have been reported for Ag(I)‚‚‚Ag-
(I)24 and are more common for the metallophilic Au(I) ion.25
It appears that the intricate hydrogen bonding present in
1 and 2 has a significant impact on the resulting coordination
compounds. The structure of compound 1 contains both
methanol solvent molecules and water molecules, both of
which are involved in hydrogen-bonded interactions with the
coordinating amino groups. The noninteracting methyl groups
of the disordered methanol molecules form “pockets” within
the packed array. Furthermore, the coordination complexes
present in compound 1 are packed around these pockets,
forming hydrogen-bonded interactions with the fluoride
counterions (N-H‚‚‚F between 2.759(7) and 2.996(7) Å) and
Figure 1. The design strategy to create a range of binding geometries
using aliphatic amines.
along the C-N bonds can be distorted upon coordination.
This third amino group is cis to the core binding mode,
creating a tripodal C3 ligand with three equal C-N vectors
available for coordination. trans-Tach11,23 is the isomeric
conformer of cis-tach, where the third amino group is trans
to the core binding mode. This axial group provides an extra
vector and therefore has the potential for higher dimensional-
ity coordination.
Structural Analysis of [Ag3(cis-tach)2]F3‚4CH3OH‚
0.5H2O (1) and [Ag3(cis-tach)2]F3‚6H2O (2). Crystallization
of a mixture of cis-tach and AgF by diffusion with ether
yields a discrete, cage-type coordination compound with the
composition M3L2 (Figure 2a). Differences in the solvent
molecules included in the crystal lattice result in the
formation of the same M3L2 cage structure but with short
Ag‚‚‚Ag contacts in compound 2 (Figure 2b). In both
structures all three cis-equatorial amino groups of the cis-
tach ligands are involved in coordinative interactions to Ag-
(I) ions. The asymmetric unit of 1 consists of two cis-tach
(24) (a) A survey of Ag(I)‚‚‚Ag(I) interactions between 2 and 5 Å in CSD
gave a median of 3.00 Å from 423 observations. (b) Density functional
theory calculations (including Lo¨wdin and Mulliken population
analysis) using the TURBOMOLE package (Treutler. O.; Ahlrichs.
R, J. Chem. Phys. 1995, 102, 346) employed TZVP basis sets and the
Becke-Perdew (BP86) exchange-correlation functional. (c)Villanneau,
R.; Proust, A.; Robert, F.; Gouzerh, P. Chem. Commun. 1998, 1491.
(25) Schmidbaur, H. Gold Bull. 1990, 23, 11.
(23) (a) Seeber, G.; Kariuki, B. M.; Cronin, L. Chem. Commun. 2002, 2912.
(b) Seeber, G.; Long, D.-L.; Kariuki, B. M.; Cronin, L. J. Chem. Soc.,
Dalton Trans. 2003, 4498.
4956 Inorganic Chemistry, Vol. 43, No. 16, 2004

Coordination Networks through the Dimensions
Figure 2. (a) Space-filling representation of the units in 1. (b) Linked units of 2 showing short Ag‚‚‚Ag contacts. Hydrogen atoms are shown as white
sticks and carbon atoms as gray sticks, and Ag(I) ions are represented by large light blue spheres and nitrogen atoms by small dark blue spheres.
the oxygen atoms from the methanol and water molecules
(N-H‚‚‚O between 2.944(7) and 2.996(7) Å). Crucially, the
absence of methanol solvent molecules in the structure of
compound 2 appears to have a marked effect on the resulting
array. Here, two cage units are aligned such that hydrogen-
bonded interactions between the amino group from each cage
and a bridging fluoride counterion (N(1)-H(1A)‚‚‚F(1)
2.952(11) Å; N(4)-H(4A)‚‚‚F(1) 2.890(12) Å) are formed.
Therefore, circumstantially, the formation of these (cage1)-
N‚‚‚F‚‚‚N(cage2) hydrogen bonds appears to be linked with
the formation of the short silver(I)-silver(I) contacts. Further,
the dimeric connected units are packed in ABAB fashion
perpendicular to the crystallographic a axis, with hydrogen
bonded interactions between the coordinating amino groups
and the fluoride counterions (N-H‚‚‚F between 2.886(11)
and 2.968(12) Å) and the oxygen atoms of the water
molecules (N-H‚‚‚O between 2.839(13) and 3.162(14) Å).
See Supporting Information a for full details and figures
showing the hydrogen-bonded networks in 1 and 2.
Structural Analysis of [Ag(cis-dach)]ClO4 (3). Crystal-
lization of a methanolic mixture of cis-dach with AgClO4
by evaporation over 2 weeks yields a polymeric chain with
a metal-to-ligand ratio of 1:1. Both equatorial amino groups
of cis-dach are involved in coordinative interactions to Ag-
(I) ions. The asymmetric unit consists of one cis-dach ligand
and one Ag(I) ion as well as one perchlorate counterion. No
solvent molecules are present in the crystal lattice. The
polymer is formed by linear Ag(I) ions coordinating to two
primary amino groups of two independent cis-dach ligands
(Figure 3). The zig-zig chains are aligned one above the
other (interchain distances are 6.345 and 8.477 Å) and are
held together in a three-dimensional hydrogen-bonded net-
work by interactions between the coordinating amino groups
and the perchlorate counterions (N-H‚‚‚O between 3.251-
(4) and 3.259(4) Å) and to a weaker extent between the
methylene protons C(1)-H(1) and the perchlorate counter-
ions (C-H‚‚‚O are between 3.377(6) and 3.491(7) Å).
Structural Analysis of [Ag(cis-tach)]NO3 (4). Crystal-
lization of an aqueous methanolic solution of cis-tach and
AgNO3 by slow evaporation over a period of several months
yields a one-dimensional coordination polymer with a metal-
to-ligand ratio of 1:1. All three cis-equatorial amino groups
of cis-tach are involved in coordinative interactions to Ag-
(I) ions. The asymmetric unit consists of one cis-tach ligand
and one Ag(I) ion as well as one nitrate counterion. No
solvent molecules are present in the crystal lattice. The 42‚6
topology is formed by two silver atoms and two cis-tach
units (both seen as three connected nodes) coordinated via
all three amino groups along the polymer (Figure 4a). Each
Ag(I) has a trigonal planar coordination sphere with three
cis amines of different ligands, forming an infinite tubular
channel. The Ag(I) atoms lie along the tube in two rows.
The N(2) and N(3) atoms coordinate the Ag(I) atoms in one
row, whereas the N(1) atoms of each ligand “wraps around”
the wall of the tube to coordinate to the Ag(I) atoms of the
second row. The metal coordination occurs exclusively in
one dimension (perpendicular to the crystallographic a axis),
forming isolated channels (interpolymer distances of 5.705,
8.367, and 10.164 Å). The tubes are held together in a three-
dimensional hydrogen-bonded network by interactions with
the nitrate counterions (N-H‚‚‚O between 3.021(2) and
3.399(2) Å), which are located between the isolated one-
dimensional polymers (Figure 4b). Each macrocycle, con-
One pertinent aim should be to extend these systems so
that the cavity size allows the encapsulation of molecules.
Such cavity containing structures could be extremely promis-
ing in a wide-variety of applications such as host-guest
chemistry26 and catalysis.27 Specifically, two examples of
M3L2 coordination compounds can be found in the literature.
The first M3L2 compound to be characterized by single-
crystal X-ray crystallography is constructed from two capping
tripodal ligands and three tetrahedral zinc(II) centers, forming
a large, almost spherical cavity (ligand to ligand distance is
9.49 Å).28 The second M3L2 structure resembles compounds
1 and 2 in the formation a cylindrical cage (ligand to ligand
distance is 10.99 Å).29 However, space-filling representations
show that the voids in compounds 1 and 2 are not of
sufficient dimensions to sustain encapsulation of solvent
molecules or even the small fluoride counterions (ligand-
to-ligand distances are 5.331 and 4.896 Å, respectively).
(26) (a) Parac, T. N.; Scherer, M.; Raymond, K. N. Angew. Chem., Int.
Ed. 2000, 39, 1239. (b) Scherer, M.; Caulder, D. L.; Johnson, D. W.;
Raymond, K. N. Angew. Chem., Int. Ed. 1999, 38, 1588. (c) Fujita,
M.; Nagao, S.; Ogura, K. J. Am. Chem. Soc. 1995, 117, 1649.
(27) (a) Ito, H.; Kusukawa, T.; Fujita, M. Chem. Lett. 2000, 598. (b)
Yoshizawa, M.; Takeyama, Y.; Kusukawa, T.; Fujita, M. Angew.
Chem., Int. Ed. 2002, 41, 1347.
(28) Sun, W.-Y.; Fan, J.; Okamura, T.; Xie, J.; Yu, K.-B.; Ueyama, N.
Chem. Eur. J. 2001, 7, 2557.
(29) Liu, H.-K.; Sun, W.-Y.; Ma, D.-J.; Yu, K.-B.; Tang, W.-X. Chem.
Commun. 2000, 591.
Inorganic Chemistry, Vol. 43, No. 16, 2004 4957

Pickering et al.
Figure 3. (a) Chain formation of 3. (b) Packing of 3 along the crystallographic a axis. Hydrogen atoms are removed for clarification. Chlorine atoms are
shown in green and oxygen atoms in red. Hydrogen atoms are shown as white sticks and carbon atoms as gray sticks, and Ag(I) ions are represented by large
light blue spheres and nitrogen atoms by small dark blue spheres.
Figure 4. (a) Macrocyclic tube formation of 4. (b) Packing of 4. (c) Macrocyclic tube formation of 5. (d) Packing of 5. Hydrogen atoms are removed for
clarification. Counterions: oxygen atoms are shown in red, fluorine atoms in light blue, and phosphate atoms in orange. Coordination polymer: carbon
atoms are represented by gray sticks, Ag(I) ions by large light blue spheres, and nitrogen atoms by small dark blue spheres.
taining two Ag(I) ions coordinating to two amino groups of
two cis-tach units, consists of 12 atoms with an inversion
center.
Structural Analysis of [Ag(trans-tach)]PF6 (5). Reaction
of trans-tach with AgPF6 and subsequent crystallization by
diffusion of ether into the methanolic reaction mixture gives
rise to isolated one-dimensional coordination polymers with
a 1:1 ligand-to-metal ratio. All three amino groups of trans-
tach are involved in coordinative interactions to Ag(I) ions.
The asymmetric unit consists of one trans-tach ligand and
4958 Inorganic Chemistry, Vol. 43, No. 16, 2004

Coordination Networks through the Dimensions
one Ag(I) ion as well as one hexafluorophosphate counterion.
The Ag(I) ion adopts a trigonal planar coordination sphere
by coordinating to two equatorial and one axial amino group
of three different trans-tach ligands. The overall structure is
tube-like (one-dimensional coordination polymers that run
perpendicular to the crystallographic b axis) with 42‚6
topological notation, where both trigonal planar silver(I) ions
and tripodal ligands are seen as three connected nodes (Figure
4c). The isolated tubes are packed in a hexagonal array, with
intertubular distances of 9.296, 9.943, and 11.727 Å. Each
tube is surrounded by six hexafluorophosphate counterions,
which form hydrogen-bonded interactions with the amino
groups of trans-tach (N-H‚‚‚F between 3.060(3) and 3.311-
(3) Å), stabilizing the tubes within a three-dimensional
hydrogen-bonded network (Figure 4d). The tubes are con-
structed by the formation of two independent 12-membered
macrocycles, both with an inversion center (intermacrocyclic
Ag‚‚‚Ag distances are 5.657 and 5.746 Å). One macrocyclic
unit is formed by the coordination of two cis-equatorial
amino groups to two Ag(I) ions, whereas the other is formed
by the coordination of the trans-axial and one equatorial
amino group to two Ag(I) ions.
The formation of compounds 4 and 5 are further examples
of synthetic routes to isolated polymeric tubes using these
ligands, as the previously reported, topologically equivalent
structure to 512 represents a staggered chain conformation.
This is formed by two chains connected through coordination
of the two cis-equatorial amino groups to an Ag(I) ion, which
are subsequently linked together via coordination of the
remaining trans-axial amino groups to the vacant trigonal
planar site of the Ag(I) ions. There are few examples of
tubular coordination structures in the literature,30,31 the most
significant tubular silver(I) coordination compound having
a diameter of 13.4 Å.30 These represent, however, tubes
within a higher dimensionality coordination network as
coordination bonds between tubes mean that they are not
truly isolated.
Structural Analysis of [Ag(cis-dapi)]CF3SO3 (6). Crys-
tallization of a methanolic mixture of cis-dapi and AgCF3-
SO3 by diffusion with ether over 2 days gives rise to a two-
dimensional coordination network with a 1:1 ligand-to-metal
ratio. The asymmetric unit consists of one cis-dapi ligand
and one silver(I) ion as well as one triflate counterion. The
trigonal planar Ag(I) centers are coordinated by two primary
amino groups and a secondary amino group of three cis-
dapi ligands. The metal coordination occurs exclusively in
two dimensions, forming layers of the well-known 63
honeycomb topological network (Figure 5). This compound
is similar to a previously reported structure with this ligand,11
which adds further evidence that the coordination geometry
of the ligand can be incorporated as part of the design
approach. The layers contain alternately orientated linear
chains, which are held together by interchain coordination
with the remaining primary amino group. Linear, intrachain
coordination occurs between silver(I) atoms and the second-
ary ring nitrogen and a single primary amine group. The
layers pack in a hexagonal array, the difference in orientation
of the AB strands resulting exclusively from the orientation
of the piperidine ring nitrogen along the crystallographic b
axis. The two-dimensional coordination polymers are held
together in a three-dimensional hydrogen-bonded network
by interactions between the coordinating amino groups and
the triflate counterions.
Summary
We have investigated the coordination behavior of a family
of rigid di- and triamino ligands with a variety of Ag(I) salts
to determine the way in which such ligand systems can be
used in the design of new functional materials with interest-
ing topologies. The ligands cis,cis-1,3,5-triaminocyclohexane,
cis,trans-1,3,5-triaminocyclohexane, cis-1,3-diaminocyclo-
hexane, and cis-3,5-diaminopiperidine each have coordinat-
ing aliphatic amino groups, the freedom and direction of
which have significant impact on the architecture of the
resulting network. The largest contributing factor, however,
appears to be the choice of anion, as both cis- and trans-
tach ligands are able to form coordination complexes of
varying dimensionalities. This appears to depend predomi-
nantly on counterion size, as exemplified by the coordination
networks formed by trans-tach. Here, the smaller nitrate
counterion is able to sit in channels within a high dimen-
sionality network (compound 7), whereas the slightly larger
counterions such as hexafluorophosphate appear too large
to do so and rather separate the coordination polymers
(compound 5). Ligand geometry is also important in the
formation of the networkssthe µ3 ligand cis-tach has three
equatorial amino groups syn to the plane of the cyclohexane
backbone, allowing the coordination as both a capping ligand
to form discrete coordination compounds (compounds 1 and
2) or a wrapping ligand in the formation of one-dimensional
coordination polymers (compound 4). The µ3 ligand trans-
tach, on the other hand, has two independent types of donor
groups anti to the plane of the cyclohexane backbone. This
enables the trans-axial amino group to coordinatively link
two silver(I) coordination chains to form one-dimensional
coordination polymers (compound 5) and also to extend
further to form three-dimensional coordination networks by
the interconnection of two independent macrocyclic subunits
(compound 7,11 Figure 6). This structure, previously reported
by us, exemplifies the scope of the ligand to form high-
dimensionality networks due to the presence of the additional
C-N vector stemming from the rigid backbone.
Conclusions
Silver(I) coordination chemistry has, to date, focused
largely on the use of planar, N-aromatic ligands. Using
inherently more flexible aliphatic amino spacer units opens
up a new area in the design of coordination networks, where
a certain degree of flexibility can be engineered into complex
formation to yield a range of networks of differing dimen-
sionalities and topologies, see Figure 7. The uncommon M3L2
(30) Hong, M.; Zhao, Y.; Su, W.; Cao, R.; Fujita, M.; Zhou, Z.; Chan, A.
S. C. Angew. Chem., Int. Ed. 2000, 39, 2468.
(31) Carlucci, L.; Ciani, G.; von Gudenberg, D. W.; Proserpio, D. M. Inorg.
Chem. 1997, 36, 3812.
Inorganic Chemistry, Vol. 43, No. 16, 2004 4959

Pickering et al.
Figure 5. (a) 63 honeycomb structure of 6. (b) View of layer formation of 6 along the crystallographic a axis. Hydrogen atoms are removed for clarification.
Counterions: oxygen atoms are shown in red, carbon atoms in gray, sulfur atoms in yellow, and fluorine atoms in light blue. Coordination polymer: carbon
atoms are represented by gray sticks, Ag(I) ions by large light blue spheres, and nitrogen atoms by small dark blue spheres.
Figure 6. (a) Three-dimensional structure of 712 showing channels along the crystallographic b axis, hydrogen atoms are removed for clarification. Oxygen
atoms are shown as red and carbon atoms as gray sticks, and Ag(I) ions are represented by large light blue spheres and nitrogen atoms by small dark blue
spheres. (b) Open and closed channel formation in 7. Hydrogen atoms are removed for clarification. The red channel is a right-handed tetragonal channel,
the dark blue channel is a left-handed octagonal channel, and the black macrocycles are closed channels within the crystallographic a/c plane.
Figure 7. Schematic summary and representation of the range of multidimensional complexes formed by the reaction of rigid amines with a variety of
silver(I) salts.
cage structure of compounds 1 and 2 provides a firm basis
on which to develop functional, cavity-containing species,
and the formation of short Ag‚‚‚Ag contacts has significant
impact on potential applications of the material. The con-
struction of the infinite tubular polymers 4 and 5 from
metal-ligand systems that possess a degree of preorgani-
zation and a number of arms that can “wrap” is a noteworthy
development in nanotube synthesis. We are currently extend-
ing this work by investigation into the coordination of these
rigid amines with other metal ions and also via derivatization
of the amino residues in order to enlarge pore dimensions
and increase the functionality of the materials.
4960 Inorganic Chemistry, Vol. 43, No. 16, 2004

Coordination Networks through the Dimensions
summary of a CSD search of Ag‚‚‚Ag interactions, and crys-
tallographic data for compounds 1-6, in the form of cif files. This
material is available free of charge via the Internet at http://
pubs.acs.org.
Acknowledgment. We thank the EPSRC, the University
of Glasgow, the Royal Society, and the Leverhulme Trust
for funding.
Supporting Information Available: A detailed description of
the hydrogen-bonded networks present in compounds 1 and 2, the
IC049786I
Inorganic Chemistry, Vol. 43, No. 16, 2004 4961