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Acta Crystallogr C. 2010 March 15; 66(Pt 3): m75–m78.
Published online 2010 February 3. doi:  10.1107/S010827011000377X
PMCID: PMC2855567

Ammine(2,2′-bipyridine-κ2 N,N′)silver(I) nitrate: a dimer formed by π–π stacking and ligand-unsupported Ag(...)Ag inter­actions


Reaction of AgNO3 and 2,2′-bipyridine (bipy) under ultrasonic treatment gave the title compound, [Ag(C10H8N2)(NH3)]NO3. The crystal structure consists of dimers formed by two symmetry-related AgI–bipy monomers connected through intra-dimer π–π stacking and ligand-unsupported Ag(...)Ag inter­actions. A crystallographic C2 axis passes through the mid-point of and is perpendicular to the Ag(...)Agi(−x + 1, y, −z + An external file that holds a picture, illustration, etc.
Object name is c-66-00m75-efi1.jpg) axis. In addition, each AgI cation is coordinated by one chelating bipy ligand and one ammine ligand, giving a trigonal coordination environment capped by the symmetry-equivalent Ag atom. Mol­ecules are assembled by Ag(...)Ag, π–π, hydrogen-bond (N—H(...)O and C—H(...)O) and weak Ag(...)π inter­actions into a three-dimensional framework. Comparing the products synthesized under different mechanical treatments, we found that reaction conditions have a significant influence on the resulting structures. The luminescence properties of the title compound are also discussed.


Self-assembled coordination structures are one of the most attractive areas of materials research due to their intriguing structural topologies and functional properties such as mol­ecular adsorption, magnetism and luminescence (Biradha et al., 2006 [triangle]; Wu et al., 2009 [triangle]; Blake, Brooks et al., 1999 [triangle]; Blake, Champness et al., 1999 [triangle]; Evans & Lin, 2002 [triangle]; Kitagawa et al., 2004 [triangle]; Yaghi et al., 2003 [triangle]), and much attention has focused on their design and construction. However, the factors that govern the formation of such complexes are complicated and include not only the inherent properties of metal ions and ligand structure, but also anion-directed inter­actions and reaction conditions (Bu et al., 2003 [triangle]; Kong et al., 2008 [triangle], 2009 [triangle]). In addition to covalent bonds, noncovalent inter­actions, such as Ag(...)Ag, π–π, hydrogen-bond and cation(...)π inter­actions, also play important roles in controlling mol­ecular packing (Pedireddi et al., 1996 [triangle]; Kolotuchin et al., 1995 [triangle]; Li et al., 2006 [triangle]; Sun et al., 2003 [triangle]; Lough et al., 2000 [triangle]; Massoud & Langer, 2009 [triangle]; Goodgame et al., 2002 [triangle]). Because the central C—C bond of bipyridine (bipy) can rotate freely, bipy cannot just be regarded as a chelating ligand (Kaes et al., 2000 [triangle]; Marchetti et al., 2007 [triangle]), but also as a potential spacer between metal centers by acting as a bridging ligand with an anti configuration (Yu et al., 2007 [triangle]; Forniés et al., 1993 [triangle]). Therefore, bipy and its derivatives are widely used in the construction of novel AgI-containing complexes incorporating diverse supra­molecular inter­actions (Hung-Low et al., 2009 [triangle]; Ye et al., 2005 [triangle]). Recently, we have pursued systematic investigations into the assembly of AgI cations with different angular and linear bipodal N-donor ligands, such as amino­pyrimidine and amino­pyrazine (e.g. Luo, Huang, Chen et al., 2008 [triangle]; Luo, Huang, Zhang et al., 2008 [triangle]; Luo et al., 2009 [triangle]; Sun, Luo, Huang et al., 2009 [triangle]; Sun, Luo, Xu et al., 2009 [triangle]; Sun, Luo, Zhang et al., 2009 [triangle]), with the principal aim of obtaining supra­molecular complexes or multifunctional coordination polymers. In an attempt to exploit the influence of synthesis conditions on the structures of the AgNO3–bipy system, we successfully obtained the title compound, (I), and the known coordination polymer, (II) {catena-poly[[(2,2′-bi­pyridine)silver(I)]-μ2-nitrato]; Bowmaker et al., 2005 [triangle]}, in the same solvent system.

An external file that holds a picture, illustration, etc.
Object name is c-66-00m75-scheme1.jpg

The asymmetric unit of (I) contains one AgI cation, one bipy ligand, one coordinated ammonia mol­ecule and one nitrate anion. As shown in Fig. 1 [triangle], the AgI cation is coordinated in a trigonal–planar fashion by three N atoms from one bipy ligand and one ammonia mol­ecule, with bond angles ranging from 72.36 (12) to 145.25 (14)°. The Ag—Nbipy bond lengths are identical within experimental error (Table 1 [triangle]) and comparable to reported values (Oxtoby et al., 2002 [triangle]; Fan et al., 2007 [triangle]; Nicola et al., 2007 [triangle]). The pyridyl rings of bipy are nearly coplanar with a twist angle of 4.8 (5)°. With an Ag—N bond length of 2.135 (4) Å, the coordinated ammonia mol­ecule plays a role as terminator, obstructing aggregation of (I). Because of the labile nature of this Ag—N bond, the presence of ammonia in the coordination sphere of the metal center offers a potential coordination site in the mol­ecule. Two symmetry-related AgI–bipy monomers aggregate to a dimer with a head-to-head arrangement through intra-dimer π–π stacking and a ligand-unsupported Ag(...)Ag inter­action (Tong et al., 1999 [triangle]), where the Ag1(...)Ag1i inter­action [symmetry code: (i) −x + 1, y, −z + ½] has a distance of 3.0456 (16) Å. This is significantly shorter than twice the van der Waals radius of AgI (3.44 Å; Bondi, 1964 [triangle]) and the completed coordination sphere of the Ag centers can thus be described as capped trigonal planar. The other cases where such short contacts exist between nonbridged AgI cations are found in Ag(imidazole)2ClO4 (Eastland et al., 1980 [triangle]) and [Cu(ethyl­ene­di­am­ine)3][Ag2(CN)4] (Kappenstein et al., 1988 [triangle]). A crys­tallo­graphic C2 axis passes through the mid-point of and is perpendicular to this Ag1(...)Ag1i axis. This weak bonding inter­action between two d 10 cations is possible via the participation of 5s and 5p orbitals which are close in energy to the 4d orbitals. Intra-dimer π–π stacking also contributes to the reinforcement of this Ag(...)Ag inter­action (Venkatalakshmi et al., 1992 [triangle]). Moreover, the π–π stacking [Cg1(...)Cg2i = 3.628 (3) Å (intra-dimer) and Cg1(...)Cg2vi = 3.711 (3) Å (inter-dimer); Cg1 and Cg2 are the centroids of the N1/C1–C5 and N2/C6–C10 rings, respectively; symmetry codes: (i) −x + 1, y, An external file that holds a picture, illustration, etc.
Object name is c-66-00m75-efi2.jpg; (vi) −x + 1, −y + 1, −z; Fig. 2 [triangle]] and weak Ag(...)C inter­actions [Ag1(...)C6vi = 3.386 (4) Å and Ag1(...)C7vi = 3.393 (5) Å] act as a ‘glue’ to reinforce the dimers, forming a column along the c axis, in which the dimers are arranged in a head-to-tail orientation. In addition, the nitrate anion acts as an acceptor and is hydrogen bonded to three different symmetry equivalents of the ammonia mol­ecules (Table 2 [triangle]). Nonclassical Cpyrid­yl—H(...)O hydrogen bonds [average C(...)O distance = 3.280 (5) Å; Table 2 [triangle]] and classical N—H(...)O hydrogen bonds link adjacent columns to form the resulting three-dimensional supra­molecular framework (Fig. 3 [triangle]).

Figure 1
The structure of (I), showing the atom-numbering scheme and the coordination environment around the AgI centre. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius.
Figure 2
A ball–stick perspective view of the π–π stacking (green dashed lines in the electronic version of the paper) between the pyridyl rings of neighboring bipy ligands and the Ag(...)Ag inter­actions (golden dashed ...
Figure 3
A ball–stick perspective view of the three-dimensional supra­molecular framework incorporating hydrogen bonds (dashed lines).
Table 1
Selected geometric parameters (Å, °)
Table 2
Hydrogen-bond geometry (Å, °)

The effects of the synthesis conditions on the structure of the AgNO3–bipy system were investigated in the ultrasonic and stirred methods with the same solvent system (methanol–water; 15 ml, 1:2 v/v). Under stirring, we could only obtain coordination polymer (II), first reported by Bowmaker et al. (2005 [triangle]). In the structure of (II), the nitrate anion not only acts as a ligand but also as a bridging anion to link AgI–bipy cationic units into one-dimensional zigzag chains. The difference between the structures of (I) and (II) originates mainly from the different mechanical treatments which cause the ammonia mol­ecule and nitrate anion to play different roles in the construction of (I) and (II).

It is known that the free bipy mol­ecule displays a weak luminescence at circa 530 nm in the solid state at room temperature. As shown in Fig. 4 [triangle], compound (I) exhibits an intense emission maximum at 469 nm upon excitation at 345 nm, which may be attributed to the intra­ligand emission from bipy (Wang et al., 2004 [triangle]). Compared with that of the free bipy mol­ecule, the blue shift and the luminescent enhancement of the emission at 469 nm may be due to the chelation of the bipy ligand to the AgI cation, which effectively increases the rigidity and coplanarity of the ligand and reduces the loss of energy by nonradiative decay of the intra­ligand emission excited state (Zhang et al., 2003 [triangle]; Qian & Wang, 2002 [triangle]).

Figure 4
Photoinduced emission spectrum of (I) (solid line) and free bipy (dotted line) in the solid state.


All reagents and solvents were used as obtained commercially without further purification. A mixture of AgNO3 (170 mg, 1 mmol) and 2,2′-bipyridine (156 mg, 1 mmol) was added to a methanol–water solvent mixture (15 ml, 1:2 v/v) under ultrasonic conditions, which helped to dissolve the white precipitate. An aqueous NH3 solution (25%) was added dropwise to the mixture to give a clear solution. The resulting solution was left to evaporate slowly in the dark at room temperature for several weeks to give crystals of (I) in the form of yellow prisms. The crystals were washed with deionized water and dried in air (yield ca 51%, based on Ag). Analysis calculated for C20H22Ag2N8O6: C 35.01, H 3.23, N 16.33%; found: C 34.95, H. 3.14, N 16.27%.

Crystal data

  • [Ag(C10H8N2)(NH3)]NO3
  • M r = 343.10
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is c-66-00m75-efi3.jpg
  • a = 17.685 (9) Å
  • b = 10.690 (5) Å
  • c = 12.748 (7) Å
  • β = 94.457 (12)°
  • V = 2403 (2) Å3
  • Z = 8
  • Mo Kα radiation
  • μ = 1.68 mm−1
  • T = 298 K
  • 0.10 × 0.08 × 0.08 mm

Data collection

  • Oxford Diffraction Gemini S Ultra diffractometer
  • Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008 [triangle]) T min = 0.850, T max = 0.877
  • 4406 measured reflections
  • 2320 independent reflections
  • 2161 reflections with I > 2σ(I)
  • R int = 0.030


  • R[F 2 > 2σ(F 2)] = 0.044
  • wR(F 2) = 0.112
  • S = 1.21
  • 2320 reflections
  • 172 parameters
  • 6 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.85 e Å−3
  • Δρmin = −0.59 e Å−3

The aromatic H atoms were generated geometrically (C—H = 0.93 Å) and allowed to ride on their parent atoms in the riding-model approximation, with U iso(H) = 1.2U eq(C). The positions of the ammonia H atoms were located from difference maps and refined with the N—H distances restrained to 0.89 (2) Å, the H(...)H distances restrained to be similar with a tolerance s.u. of 0.04 Å and with U iso(H) = 1.5U eq(N).

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 [triangle]); cell refinement: CrysAlis RED (Oxford Diffraction, 2008 [triangle]); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: DIAMOND (Brandenburg, 2008 [triangle]) and SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010 [triangle]).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S010827011000377X/mx3026sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S010827011000377X/mx3026Isup2.hkl


This work was supported financially by the National Natural Science Foundation of China (grant No. 20721001) and the 973 Project (grant No. 2007CB815301).


Supplementary data for this paper are available from the IUCr electronic archives (Reference: MX3026). Services for accessing these data are described at the back of the journal.


  • Biradha, K., Sarkar, M. & Rajput, L. (2006). Chem. Commun.pp. 4169–4179. [PubMed]
  • Blake, A. J., Brooks, N. R., Champness, N. R., Cooke, P. A., Deveson, A. M., Fenske, D., Hubberstey, P., Li, W. S. & Schröder, M. (1999). J. Chem. Soc. Dalton Transpp. 2103–2110.
  • Blake, A. J., Champness, N. R., Hubberstey, P., Li, W.-S., Withersby, M. A. & Schröder, M. (1999). Coord. Chem. Rev.183, 117–138.
  • Bondi, A. (1964). J. Phys. Chem 68, 441–451.
  • Bowmaker, G. A., Marfuah, E. S., Skelton, B. W. & White, A. H. (2005). Inorg. Chim. Acta, 358, 4371–4388.
  • Brandenburg, K. (2008). DIAMONDVersion 3.1f. Crystal Impact GbR, Bonn, Germany.
  • Bu, X. H., Xie, Y. B., Li, J. R. & Zhang, R. H. (2003). Inorg. Chem.42, 7422–7430. [PubMed]
  • Eastland, G. W., Mazid, M. A., Russell, D. R. & Symons, M. C. R. (1980). J. Chem. Soc. Dalton Trans.pp. 1682–1687.
  • Evans, O. R. & Lin, W. (2002). Acc. Chem. Res 35, 511–522. [PubMed]
  • Fan, J., Wang, Y., Blake, A. J., Wilson, C., Davies, E. S., Khlobystov, A. N. & Schröder, M. (2007). Angew. Chem. Int. Ed.46, 8013–8016. [PubMed]
  • Forniés, J., Navarro, R., Sicilia, V. & Tomás, M. (1993). Inorg. Chem 32, 3675–3681.
  • Goodgame, D. M. L., Grachvogel, D. A. & Williams, D. J. (2002). J. Chem. Soc. Dalton Transpp. 2259–2260.
  • Hung-Low, F., Renz, A. & Klausmeyer, K. K. (2009). Polyhedron, 28, 407–415.
  • Kaes, C., Katz, A. & Hosseini, M. W. (2000). Chem. Rev.100, 3553–3590. [PubMed]
  • Kappenstein, C., Ouali, A., Guerin, M., Cernák, J. & Chomic, J. (1988). Inorg. Chim. Acta, 147, 189–197.
  • Kitagawa, S., Kitaura, R. & Noro, S. (2004). Angew. Chem. Int. Ed.43, 2334–2375. [PubMed]
  • Kolotuchin, S. V., Fenlon, E. E., Wilson, S. R., Loweth, C. J. & Zimmerman, S. C. (1995). Angew. Chem. Int. Ed.34, 2654–2657.
  • Kong, X. J., Ren, Y. P., Long, L. S., Huang, R. B., Zheng, L. S. & Kurmoo, M. (2008). CrystEngComm, 10, 1309–1314.
  • Kong, X. J., Zhuang, G. L., Ren, Y. P., Long, L. S., Huang, R. B. & Zheng, L. S. (2009). Dalton Trans.pp. 1707–1709. [PubMed]
  • Li, F., Li, T. H., Yuan, D. Q., Lv, J. & Cao, R. (2006). Inorg. Chem. Commun.9, 691–694.
  • Lough, A. J., Wheatley, P. S., Ferguson, G. & Glidewell, C. (2000). Acta Cryst. B56, 261–272. [PubMed]
  • Luo, G.-G., Huang, R.-B., Chen, J.-H., Lin, L.-R. & Zheng, L.-S. (2008). Polyhedron, 27, 2791–2798.
  • Luo, G.-G., Huang, R.-B., Zhang, N., Lin, L.-R. & Zheng, L.-S. (2008). Polyhedron, 27, 3231–3238.
  • Luo, G.-G., Sun, D., Xu, Q.-J., Lin, L.-R., Huang, R.-B. & Zheng, L.-S. (2009). Inorg. Chem. Commun.12, 436–439.
  • Marchetti, E. F., Pettinari, C., Pettinari, R., Skelton, B. W. & White, A. H. (2007). Inorg. Chim. Acta, 360, 1388–1413.
  • Massoud, A. A. & Langer, V. (2009). Acta Cryst. C65, m198–m200. [PubMed]
  • Nicola, C. D., Marchetti, E. F., Pettinari, C., Skelton, B. W. & White, A. H. (2007). Inorg. Chim. Acta, 360, 1433–1450.
  • Oxford Diffraction (2008). CrysAlis CCD and CrysAlis REDVersion Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.
  • Oxtoby, N. S., Blake, A. J., Champness, N. R. & Wilson, C. (2002). Proc. Natl Acad. Sci. USA, 99, 4905–4910. [PubMed]
  • Pedireddi, V. R., Jones, W., Chorlton, A. P. & Docherty, R. (1996). Chem. Communpp. 997–998.
  • Qian, G. & Wang, M. (2002). Mater. Lett.56, 71–75.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Sun, D., Luo, G.-G., Huang, R.-B., Zhang, N. & Zheng, L.-S. (2009). Acta Cryst. C65, m305–m307. [PubMed]
  • Sun, D., Luo, G.-G., Xu, Q.-J., Zhang, N., Jin, Y.-C., Zhao, H.-X., Lin, L.-R., Huang, R.-B. & Zheng, L.-S. (2009). Inorg. Chem. Commun.12, 782–784.
  • Sun, D., Luo, G.-G., Zhang, N., Chen, J.-H., Huang, R.-B., Lin, L.-R. & Zheng, L.-S. (2009). Polyhedron, 28, 2983–2988.
  • Sun, D. F., Cao, R., Sun, Y. Q., Bi, W. H., Li, X. J., Wang, Y. Q., Shi, Q. & Li, X. (2003). Inorg. Chem 42, 7512–7518. [PubMed]
  • Tong, M. L., Chen, X. M., Ye, B. H. & Ji, L. A. (1999). Angew. Chem. Int. Ed.38, 2237–2239. [PubMed]
  • Venkatalakshmi, N., Rajasekharan, M. V. & Mathews, I. I. (1992). Transition Met. Chem.17, 455–457.
  • Wang, X. L., Qin, C., Wang, E. B., Li, Y. G., Hao, N., Hu, C. W. & Xu, L. (2004). Inorg. Chem.43, 1850–1856. [PubMed]
  • Westrip, S. (2010). publCIFIn preparation.
  • Wu, S. T., Ma, L. Q., Long, L. S., Zheng, L. S. & Lin, W. B. (2009). Inorg. Chem 48, 2436–2442. [PubMed]
  • Yaghi, O. M., O’Keeffe, M., Ockwig, N. W., Chae, H. K., Eddaoudi, M. & Kim, J. (2003). Nature (London), 423, 705–714. [PubMed]
  • Ye, B. H., Tong, M. L. & Chen, X. M. (2005). Coord. Chem. Rev.249, 545–565.
  • Yu, Y., Wei, Y., Broer, R. & Wu, K. (2007). Inorg. Chem. Commun.10, 1289–1293.
  • Zhang, L.-Y., Liu, G.-F., Zheng, S.-L., Ye, B.-H., Zhang, X.-M. & Chen, X.-M. (2003). Eur. J. Inorg. Chem.pp. 2965–2971.

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