Crystal structure of μ-cyanido-1:2κ2N:C-dicyanido-1κC,2κC-bis­(quinolin-8-amine-1κ2N,N′)-2-silver(I)-1-silver(II): rare occurrence of a mixed-valence AgI,II compound

Setifi, Z.; Bernès, S.; Pérez, O.; Setifi, F.; Rouag, D.-A.

doi:10.1107/S2056989015009664

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ISSN: 2056-9890

Volume 71| Part 6| June 2015| Pages 698-701

doi:10.1107/S2056989015009664

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Crystal structure of μ-cyanido-1:2κ²N:C-dicyanido-1κC,2κC-bis(quinolin-8-amine-1κ²N,N′)-2-silver(I)-1-silver(II): rare occurrence of a mixed-valence Ag^I,II compound

Zouaoui Setifi,^a,^b Sylvain Bernès,^c ^* Olivier Pérez,^d Fatima Setifi ^a ^* and Djamil-Azzeddine Rouag ^b

^aLaboratoire de Chimie, Ingénierie Moléculaire et Nanostructures (LCIMN), Université Ferhat Abbas Sétif 1, Sétif 19000, Algeria, ^bUnité de Recherche de Chimie de l'Environnement et Moléculaire Structurale (CHEMS), Université Constantine 1, Constantine 25000, Algeria, ^cInstituto de Física, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue., Mexico, and ^dLaboratoire CRISMAT, UMR 6508 CNRS, ENSICAEN, 6 Boulevard du Maréchal Juin, 14050 Caen Cedex 04, France
^*Correspondence e-mail: sylvain_bernes@Hotmail.com, fat_setifi@yahoo.fr

Edited by A. J. Lough, University of Toronto, Canada (Received 9 May 2015; accepted 19 May 2015; online 23 May 2015)

The title dinuclear complex, [Ag₂(CN)₃(C₉H₈N₂)₂], may be considered as an Ag^II compound with the corresponding metal site coordinated by two bidentate quinolin-8-amine molecules, one cyanide group and one dicyanidoargentate(I) anion, [Ag(CN)₂]⁻. Since this latter ligand contains an Ag^I atom, the complex should be a class 1 or class 2 mixed-valence compound, according to the Robin–Day classification. The Ag^II atom is six-coordinated in a highly distorted octahedral geometry, while the Ag^I atom displays the expected linear geometry. In the crystal, the amino groups of the quinolin-8-amine ligands form N—H⋯N hydrogen bonds with the N atoms of the non-bridging cyanide ligands, forming a two-dimensional network parallel to (102). The terminal cyanide ligands are not engaged in polymeric bonds and the title compound is an authentic molecular complex. The title molecule is thus a rare example of a stable Ag^I,II complex, and the first mixed-valence Ag^I,II molecular complex characterized by X-ray diffraction.

Keywords: crystal structure; silver; mixed valency; quinoline.

CCDC reference: 1401857

1. Chemical context

The coordination chemistry of silver is clearly dominated by Ag^I complexes. The oxidation state Ag^II, with a paramagnetic 4d⁹ electronic configuration, is however present in inorganic species like AgF₂, a compound which readily decomposes in water, and is even able to oxidize SiCl₄ (Grochala & Mazej, 2015 ). Ag^II is also stable in bimetallic perfluorinated compounds Ag^IIM^IVF₆, with M = Pt, Pd, Ti, Rh, Sn and Pb. In these solids, the Ag^II sites are bonded to six F atoms, in an octahedral coordination geometry distorted by the Jahn–Teller effect. In contrast, AgO, precipitated from Ag in presence of K₂S₂O₈ in a basic medium, is a diamagnetic mixed-valence Ag^I,III oxide, rather than a Ag^II compound (Housecroft & Sharpe, 2012 ). Some actual Ag^II coordination complexes may be formed in solution, for example [Ag(bpy)₂]²⁺, which follows the Curie law with a magnetic moment close to the spin-only value expected for a d⁹ system (Kandaiah et al., 2012 ).

Recently, polynitrile and cyanidometallate anions have received considerable attention because of their importance in both coordination chemistry and in molecular materials chemistry (Atmani et al., 2008 ; Benmansour et al., 2008 , 2009 , 2012 ; Setifi et al., 2013 ; Setifi, Lehchili et al., 2014 ; Setifi, Charles et al., 2014 ). In view of the possible roles of these versatile anionic ligands, we have been interested in using them in combination with other chelating or bridging neutral co-ligands to explore their structural and electronic characteristics in the extensive field of molecular materials exhibiting the spin-crossover (SCO) phenomenon (Dupouy et al., 2008 , 2009 ; Setifi et al., 2009 ; Setifi, Charles et al., 2014; Setifi, Milin et al., 2014 ). During the course of attempts to prepare such complexes, using the dicyanidoargentate(I) anion, we isolated the title compound, whose structure is described here.

2. Structural commentary

The title complex (Fig. 1) is a binuclear silver compound placed in a general position, in which metallic sites present contrasting coordination environments. Ag1 is six-coordinated by two quinolin-8-amine bidentate ligands, one terminal cyanide ligand, and one bridging cyanide ligand. The quinoline ring system N1–C8 is slightly twisted, with a r.m.s. deviation of 0.04 Å, while the other, N11–C18, may be considered as planar (rms deviation: 0.01 Å). Quinoline ligands are arranged cis in the octahedral coordination polyhedron, and their mean planes make a dihedral angle of 58.71 (5)°. The amino groups bonded to C8 and C18 are trans to the cyanide ligands. The octahedral geometry around Ag1 is distorted, mainly because of bite angles for quinoline ligands, N1—Ag1—N9 = 69.59 (7)° and N11—Ag1—N19 = 71.29 (7)°. The coordination of the terminal cyanide ligand, C20≡N21 is through the C atom, as determined from the structure refinement (see Refinement section). This orientation seems to be favored by the availability of atom N21 as an acceptor for hydrogen bonding with symmetry-related molecules in the crystal (Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N9—H9A⋯N21ⁱ	0.79 (3)	2.36 (3)	3.143 (4)	169 (3)
N9—H9B⋯N21ⁱⁱ	0.85 (3)	2.23 (3)	3.075 (3)	172 (3)
N19—H19A⋯N21ⁱⁱ	0.77 (3)	2.48 (3)	3.205 (4)	157 (3)
N19—H19B⋯N25ⁱⁱⁱ	0.90 (3)	2.19 (3)	3.087 (4)	175 (3)
Symmetry codes: (i) -x+1, -y+2, -z+1; (ii) x, y-1, z; (iii) $[-x+2, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Figure 1
The molecular structure of the title complex, with displacement ellipsoids drawn at the 30% probability level.

Metal site Ag2 has a linear coordination with two cyanide ligands. Both ligands are coordinated through their C atoms (C22 and C24), and the coordination angle C22—Ag2—C24 = 176.05 (11)°, close to the ideal angle of 180° expected for an sp hybridization of the metal. Site Ag2 may thus be confidently assigned to a Ag^I coordination site, and charge balance for the complex should then set the oxidation state for the octahedral metal as Ag^II, with a formal hybridization sp³d². The title complex is a mixed-valence compound, with valences localized on a single site. According to the Robin–Day classification (Day et al., 2008 ), this compound should thus be a class 1 or class 2 mixed-valence compound. The deep-red color of the crystals should be the result of the π^*←4d(Ag) metal-to-ligand charge transfer, rather than a consequence of an intervalence charge transfer of a class 2 complex. Indeed, porphyrinato–Ag^II compounds are generally purple or red compounds (e.g. Xu et al., 2007 ).

Cyanide ligand C22≡N23 bridges metal sites Ag1 and Ag2, with oxidation states II and I respectively. The best structure refinement shows that this ligand is not disordered: the C atom is bonded to Ag⁺, and the N atom to the Ag^II atom. This orientation observed for the bridge is consistent with the Pearson's HSAB principle (Pearson, 2005 ). The cyanide Lewis base is considered as a soft ligand, which preferentially forms covalent bonds with soft Lewis acid, like Ag⁺. However, the heteronuclear nature of this ligand induces an asymmetric character for the softness: based on the absolute electronegativity criterion, the C side of the cyanide ligand is expected to be softer than the N side. On the other hand, regarding the acid component of the coordination bonds, Ag⁺ is expected to be softer than Ag²⁺, due to the charge difference, which makes Ag⁺ more polarizable than Ag²⁺. The most stable acid–base interactions for the bridging mode of ligand C22≡N23 is thus Ag⁺—C≡N—Ag²⁺, as observed in the X-ray-based structure refinement. From the reactivity point of view, the dicyanidoargentate(I) anion, [Ag(CN)₂]⁻, used as starting material, preserves the κC coordination mode for the cyanide groups in the product. This anion thus acts as a ligand to the oxidized Ag^II atom formed during the reaction. The same κC coordination is observed for the terminal cyanide group bonded to Ag²⁺, indicating that this fragment [Ag(CN)]⁺ is also produced from dicyanidoargentate, probably prior to aminoquinoline coordination.

3. Supramolecular features

As described in the previous section, both terminal cyanide ligands are bonded to Ag1 and Ag2 as κC ligands, allowing the N terminus to act as acceptor sites for hydrogen bonding (Ramabhadran et al., 2014 ). Amino groups of aminoquinoline ligands are the donors for these contacts (Table 1), forming a two-dimensional supramolecular network parallel to (102) (Fig. 2). Molecules are aggregated through a centrosymmetric R₄²(8) ring, where the donor group is the terminal cyanide C20/N21 bonded to Ag1. The same cyanide ligand is engaged in R₂¹(6) rings, where donors are from two different amino groups. This basic pattern of fused rings propagates in the [010] direction, via larger R₂²(10) rings. Finally, these rows of molecules are connected in the crystal via the long arms Ag2—C24≡N25, which take part in large R₃³(19) rings. The shortest metal⋯metal distance is observed in these rings involving Ag⁺ ions: Ag2⋯Ag2ⁱ = 3.9680 (3) Å [symmetry code (i): −x + 2, y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ].

Figure 2
Part of the crystal structure of the title complex, emphasizing the N—H⋯N hydrogen bonds (dashed red lines) forming R rings. The green molecule corresponds to the asymmetric unit.

Although the resulting supramolecular structure is compact, hydrogen bonds, with H⋯N contacts in the range 2.19 (3)–2.48 (3) Å, should be considered as interactions of moderate strength. The crystallized compound is an authentic molecular complex, in which the terminal cyanide ligands are not engaged in polymeric bonds.

4. Database survey

Complexes characterized by X-ray diffraction which include at least one Ag²⁺ ion are much less common than Ag⁺ complexes. An estimation using the field `NAME = silver(II)' or `NAME = silver(I)' in the current release of the CSD (version 5.36 with all updates; Groom & Allen, 2014 ), affords 63 and more than 8000 hits, respectively. Within Ag^I complexes, the occurrence of the dicyanidoargentate ion is significant. It has been used not only as a counter-ion (e.g. Stork et al., 2005 ) but also as a ligand for numerous transition-metal ions, including Ag⁺ (Lin et al., 2005 ).

For non-polymeric compounds, the most common coordination for Ag²⁺ is the square-planar [AgN₄] arrangement, found in porphyrin derivatives and tetra-aza cyclic ligands (e.g. Xu et al., 2007). However, a few cases of six-coordinate Ag²⁺ species have been characterized, with N-donor ligands (Clark et al., 2009 ) and S-donor ligands (Shaw et al., 2006 ). Compounds with both Ag⁺ and Ag²⁺ ions which have been X-ray characterized seem to be very scarce. A 1D polymeric mixed-valent Ag^I/Ag^II polymer was obtained by reacting AgNO₃, Na₂S₂O₈ and pyrazine in a CH₃CN/H₂O mixture, and the presence of Ag²⁺ was confirmed by ESR (Sun et al., 2010 ). The two other cases retrieved from the CSD are ionic compounds, in which tetraazacyclotetradecane derivatives coordinate the Ag²⁺ ion in a square-planar geometry, while the Ag⁺ ion is present in the anionic polymeric part (Wang & Mak, 2001 ) or in an anionic cluster (Wang et al., 2002 ). The title complex is, as far we can see, the first non-polymeric and non-ionic mixed-valence Ag^I,II compound characterized by X-ray diffraction.

5. Synthesis and crystallization

The title compound was obtained under solvothermal conditions from a mixture of iron(II) sulfate heptahydrate (28 mg, 0.1 mmol), quinolin-8-amine (30 mg, 0.2 mmol) and potassium dicyanidoargentate (40 mg, 0.2 mmol) in water–ethanol (4:1 v/v, 20 ml). The mixture was transferred to a Teflon-lined autoclave and heated at 423 K for 48 h. The autoclave was then allowed to cool to ambient temperature. Deep-red crystals of the title compound were collected by filtration, washed with water and dried in air (yield 30%).

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. Special attention was paid to the accurate orientation for the three cyanide ligands in the asymmetric unit. For each C≡N group, two refinements were carried out with each possible orientation, and the best model was retained on the basis of R₁ and wR₂ factors, and ADP for the C and N sites. For example, wR₂ for all data rises from 8.78% to ca. 9.30% if one cyanide ligand bonded to Ag2 is inverted. No evidence for disordered cyanido groups was detected in the difference maps. All C-bonded H atoms were placed in calculated positions and refined as riding atoms, with C—H bond lengths fixed to 0.93 Å. Amino H atoms bonded to N9 and N19 were found in a difference map and refined freely. For all H atoms, isotropic displacement parameters were calculated as U_iso(H) = 1.2U_eq(carrier atom).

Table 2
Experimental details

Crystal data
Chemical formula	[Ag₂(CN)₃(C₉H₈N₂)₂]
M_r	582.15
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	13.5449 (7), 6.9385 (3), 22.3824 (11)
β (°)	94.767 (2)
V (Å³)	2096.25 (17)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	1.89
Crystal size (mm)	0.27 × 0.23 × 0.18

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Sheldrick, 2003 )
T_min, T_max	0.615, 0.754
No. of measured, independent and observed [I > 2σ(I)] reflections	27103, 7113, 5226
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.750

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.088, 1.02
No. of reflections	7113
No. of parameters	283
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	1.70, −0.56
Computer programs: APEX2 and SAINT (Bruker, 2009 ), SHELXS2014/7 (Sheldrick, 2008 ), SHELXL2014/7 (Sheldrick, 2015 ) and Mercury (Macrae et al., 2008 ).

Supporting information

CCDC reference: 1401857

Crystal structure: contains datablocks I, global. DOI: 10.1107/S2056989015009664/lh5764sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S2056989015009664/lh5764Isup2.hkl

checkCIF report

Chemical context top

The coordination chemistry of silver is clearly dominated by Ag^I complexes. The oxidation state Ag^II, with a paramagnetic 4d⁹ electronic configuration, is however present in inorganic species like AgF₂, a compound which readily decomposes in water, and is even able to oxidize SiCl₄ (Grochala & Mazej, 2015). Ag^II is also stable in bimetallic perfluorinated compounds Ag^IIM^IVF₆, with M = Pt, Pd, Ti, Rh, Sn and Pb. In these solids, the Ag^II sites are bonded to six F atoms, in an octahedral coordination geometry distorted by the Jahn–Teller effect. In contrast, AgO, precipitated from Ag in presence of K₂S₂O₈ in a basic medium, is a diamagnetic mixed-valence Ag^I,III oxide, rather than a Ag^II compound (Housecroft & Sharpe, 2012). Some actual Ag^II coordination complexes may be formed in solution, for example [Ag(bpy)₂]²⁺, which follows the Curie law with a magnetic moment close to the spin-only value expected for a d⁹ system (Kandaiah et al., 2012).

Recently, polynitrile and cyanometallates anions have received considerable attention because of their importance in both coordination chemistry and in molecular materials chemistry (Atmani et al., 2008; Benmansour et al., 2008, 2009, 2012; Setifi et al., 2013; Setifi, Lehchili et al., 2014; Setifi, Charles et al., 2014). In view of the possible roles of these versatile anionic ligands, we have been interested in using them in combination with other chelating or bridging neutral co-ligands to explore their structural and electronic characteristics in the extensive field of molecular materials exhibiting the spin-crossover (SCO) phenomenon (Dupouy et al., 2008, 2009; Setifi et al., 2009; Setifi, Charles et al., 2014; Setifi, Milin et al., 2014). During the course of attempts to prepare such complexes, using the dicyanoargentate anion, we isolated the title compound, whose structure is described here.

Structural commentary top

The title complex (Fig. 1) is a bimetallic compound placed in a general position, in which metallic centres present contrasting coordination environments. Ag1 is six-coordinated by two quinolin-8-amine bidentate ligands, one terminal cyanide ligand, and one bridging cyanide ligand. The quinoline ring system N1–C8 is slightly twisted, with a r.m.s. deviation of 0.04 Å, while the other, N11–C18, may be considered as planar (rms deviation: 0.01 Å). Quinoline ligands are arranged cis in the octahedral coordination polyhedron, and their mean planes make a dihedral angle of 58.71 (5)°. The amino groups bonded to C8 and C18 are trans to the cyanide ligands. The octahedral geometry around Ag1 is distorted, mainly because of bite angles for quinoline ligands, N1—Ag1—N9 = 69.59 (7)° and N11—Ag1—N19 = 71.29 (7)°. The coordination of the terminal cyanide ligand, C20≡N21 is through the C atom, as determined from the structure refinement (see Refinement section). This orientation seems to be favored by the availability of atom N21 as an acceptor for hydrogen bonding with symmetry-related molecules in the crystal (Table 1).

Metal centre Ag2 has a linear coordination with two cyanide ligands. Both ligands are coordinated through their C atoms (C22 and C24), and the coordination angle C22—Ag2—C24 = 176.05 (11)°, close to the ideal angle of 180° expected for an sp hybridization of the metal. Site Ag2 may thus be confidently assigned to a Ag^I coordination site, and charge balance for the complex should then set the oxidation state for the octahedral metal as Ag^II, with a formal hybridization sp³d². The title complex is a mixed-valence compound, with valences localized on a single site. According to the Robin–Day classification (Day et al., 2008), this compound should thus be a class 1 or class 2 mixed-valence compound. The deep-red color of the crystals should be the result of the π^*←4d(Ag) metal-to-ligand charge transfer, rather than a consequence of an intervalence charge transfer of a class 2 complex. Indeed, porphyrinato–Ag^II compounds are generally purple or red compounds (e.g. Xu et al., 2007).

Cyanide ligand C22≡N23 bridges metal centres Ag1 and Ag2, with oxidation states II and I respectively. The best structure refinement shows that this ligand is not disordered: the C atom is bonded to Ag⁺, and the N atom to the Ag²⁺ centre. This orientation observed for the bridge is consistent with the Pearson's HSAB principle (Pearson, 2005). The cyanide Lewis base is considered as a soft ligand, which preferentially forms covalent bonds with soft Lewis acid, like Ag⁺. However, the heteronuclear nature of this ligand induces an asymmetric character for the softness: based on the absolute electronegativity criterion, the C side of the cyanide ligand is expected to be softer than the N side. On the other hand, regarding the acid component of the coordination bonds, Ag⁺ is expected to be softer than Ag²⁺, due to the charge difference, which makes Ag⁺ more polarizable than Ag²⁺. The most stable acid–base interactions for the bridging mode of ligand C22≡N23 is thus Ag⁺—C≡N—Ag²⁺, as observed in the X-ray structure. From the reactivity point of view, the dicyanoargentate anion, [Ag(CN)₂]^-, used as starting material, preserves the κC coordination mode for the cyanide groups in the product. This anion thus acts as a ligand to the oxidized Ag²⁺ centre formed during the reaction. The same κC coordination is observed for the terminal cyanide group bonded to Ag²⁺, indicating that this fragment [Ag(CN)]⁺ is also produced from dicyanoargentate, probably prior to aminoquinoline coordination.

Supramolecular features top

As described in the previous section, both terminal cyanide ligands are bonded to Ag1 and Ag2 as κC ligands, allowing the N terminus to act as acceptor sites for hydrogen bonding (Ramabhadran et al., 2014). Amino groups of aminoquinoline ligands are the donors for these contacts (Table 1), forming a two-dimensional supramolecular network parallel to (102) (Fig. 2). Molecules are aggregated through a centrosymmetric R₄²(8) ring, where the donor group is the terminal cyanide C20/N21 bonded to Ag1. The same cyanide ligand is engaged in R₂¹(6) rings, where donors are from two different amino groups. This basic pattern of fused rings propagates in the [010] direction, via larger R₂²(10) rings. Finally, these rows of molecules are connected in the crystal via the long arms Ag2—C24≡N25, which take part in large R₃³(19) rings. The shortest metal···metal distance is observed in these rings involving Ag⁺ ions: Ag2···Ag2ⁱ = 3.9680 (3) Å [symmetry code (i): -x + 2, y + 1/2, -z + 1/2].

Although the resulting supramolecular structure is compact, hydrogen bonds, with H···N contacts in the range 2.19 (3)–2.48 (3) Å, should be considered as interactions of moderate strength. The crystallized compound is an authentic molecular complex, in which the terminal cyanide ligands are not engaged in polymeric bonds.

Database survey top

Complexes characterized by X-ray diffraction which include at least one Ag²⁺ ion are much less common than Ag⁺ complexes. An estimation using the field "NAME = silver(II)" or "NAME = silver(I)" in the current release of the CSD (version 5.36 with all updates; Groom & Allen, 2014), affords 63 and more than 8000 hits, respectively. Within Ag^I complexes, the occurrence of the dicyanoargentate ion is significant. It has been used not only as a counter-ion (e.g. Stork et al., 2005) but also as a ligand for numerous transition metal ions, including Ag⁺ (Lin et al., 2005).

For non-polymeric compounds, the most common coordination for Ag²⁺ is the square-planar [AgN₄] arrangement, found in porphyrin derivatives and tetra-aza cyclic ligands (e.g. Xu et al., 2007). However, a few cases of six-coordinated Ag²⁺ species have been characterized, with N-donor ligands (Clark et al., 2009) and S-donor ligands (Shaw et al., 2006). Compounds with both Ag⁺ and Ag²⁺ ions which have been X-ray characterized seem to be very scarce. A 1D polymeric mixed-valent Ag^I/Ag^II polymer was obtained by reacting AgNO₃, Na₂S₂O₈ and pyrazine in a CH₃CN/H₂O mixture, and the presence of Ag²⁺ was confirmed by ESR (Sun et al., 2010). The two other cases retrieved from the CSD are ionic compounds, in which tetraazacyclotetradecane derivatives coordinate the Ag²⁺ ion in a square-planar geometry, while the Ag⁺ ion is present in the anionic polymeric part (Wang & Mak, 2001) or in an anionic cluster (Wang et al., 2002). The title complex is, as far we can see, the first non-polymeric and non-ionic mixed-valence Ag^I,II compound characterized by X-ray diffraction.

Synthesis and crystallization top

The title compound was obtained under solvothermal conditions from a mixture of iron(II) sulfate heptahydrate (28 mg, 0.1 mmol), quinolin-8-amine (30 mg, 0.2 mmol) and potassium dicyanoargentate (40 mg, 0.2 mmol) in water–ethanol (4:1 v/v, 20 ml). The mixture was transferred to a Teflon-lined autoclave and heated at 423 K for 48 h. The autoclave was then allowed to cool to ambient temperature. Deep-red crystals of the title compound were collected by filtration, washed with water and dried in air (yield 30%).

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 2. Special attention was paid to the accurate orientation for the three cyanide ligands in the asymmetric unit. For each C≡N group, two refinements were carried out with each possible orientation, and the best model was retained on the basis of R₁ and wR₂ factors, and ADP for the C and N sites. For example, wR₂ for all data rises from 8.78% to ca. 9.30% if one cyanide ligand bonded to Ag2 is inverted. No evidence for disordered cyano groups was detected in the difference maps. All C-bonded H atoms were placed in calculated positions and refined as riding atoms, with C—H bond lengths fixed to 0.93 Å. Amino H atoms bonded to N9 and N19 were found in a difference map and refined freely. For all H atoms, isotropic displacement parameters were calculated as U_iso(H) = 1.2U_eq(carrier atom).

Related literature top

For related literature, see: Atmani et al. (2008); Benmansour et al. (2008, 2009, 2012); Clark et al. (2009); Day et al. (2008); Dupouy et al. (2008, 2009); Grochala & Mazej (2015); Groom & Allen (2014); Housecroft & Sharpe (2012); Kandaiah et al. (2012); Lin et al. (2005); Pearson (2005); Ramabhadran et al. (2014); Setifi et al. (2009, 2013); Setifi, Charles, Houille, Thétiot, Triki, Gómez-García & Pillet (2014); Setifi, Lehchili, Setifi, Beghidja, Ng & Glidewell (2014); Setifi, Milin, Charles, Thétiot, Triki & Gómez-García (2014); Shaw et al. (2006); Stork et al. (2005); Sun et al. (2010); Wang & Mak (2001); Wang et al. (2002); Xu et al. (2007).

Structure description top

The coordination chemistry of silver is clearly dominated by Ag^I complexes. The oxidation state Ag^II, with a paramagnetic 4d⁹ electronic configuration, is however present in inorganic species like AgF₂, a compound which readily decomposes in water, and is even able to oxidize SiCl₄ (Grochala & Mazej, 2015). Ag^II is also stable in bimetallic perfluorinated compounds Ag^IIM^IVF₆, with M = Pt, Pd, Ti, Rh, Sn and Pb. In these solids, the Ag^II sites are bonded to six F atoms, in an octahedral coordination geometry distorted by the Jahn–Teller effect. In contrast, AgO, precipitated from Ag in presence of K₂S₂O₈ in a basic medium, is a diamagnetic mixed-valence Ag^I,III oxide, rather than a Ag^II compound (Housecroft & Sharpe, 2012). Some actual Ag^II coordination complexes may be formed in solution, for example [Ag(bpy)₂]²⁺, which follows the Curie law with a magnetic moment close to the spin-only value expected for a d⁹ system (Kandaiah et al., 2012).

As described in the previous section, both terminal cyanide ligands are bonded to Ag1 and Ag2 as κC ligands, allowing the N terminus to act as acceptor sites for hydrogen bonding (Ramabhadran et al., 2014). Amino groups of aminoquinoline ligands are the donors for these contacts (Table 1), forming a two-dimensional supramolecular network parallel to (102) (Fig. 2). Molecules are aggregated through a centrosymmetric R₄²(8) ring, where the donor group is the terminal cyanide C20/N21 bonded to Ag1. The same cyanide ligand is engaged in R₂¹(6) rings, where donors are from two different amino groups. This basic pattern of fused rings propagates in the [010] direction, via larger R₂²(10) rings. Finally, these rows of molecules are connected in the crystal via the long arms Ag2—C24≡N25, which take part in large R₃³(19) rings. The shortest metal···metal distance is observed in these rings involving Ag⁺ ions: Ag2···Ag2ⁱ = 3.9680 (3) Å [symmetry code (i): -x + 2, y + 1/2, -z + 1/2].

For non-polymeric compounds, the most common coordination for Ag²⁺ is the square-planar [AgN₄] arrangement, found in porphyrin derivatives and tetra-aza cyclic ligands (e.g. Xu et al., 2007). However, a few cases of six-coordinated Ag²⁺ species have been characterized, with N-donor ligands (Clark et al., 2009) and S-donor ligands (Shaw et al., 2006). Compounds with both Ag⁺ and Ag²⁺ ions which have been X-ray characterized seem to be very scarce. A 1D polymeric mixed-valent Ag^I/Ag^II polymer was obtained by reacting AgNO₃, Na₂S₂O₈ and pyrazine in a CH₃CN/H₂O mixture, and the presence of Ag²⁺ was confirmed by ESR (Sun et al., 2010). The two other cases retrieved from the CSD are ionic compounds, in which tetraazacyclotetradecane derivatives coordinate the Ag²⁺ ion in a square-planar geometry, while the Ag⁺ ion is present in the anionic polymeric part (Wang & Mak, 2001) or in an anionic cluster (Wang et al., 2002). The title complex is, as far we can see, the first non-polymeric and non-ionic mixed-valence Ag^I,II compound characterized by X-ray diffraction.

Synthesis and crystallization top

The title compound was obtained under solvothermal conditions from a mixture of iron(II) sulfate heptahydrate (28 mg, 0.1 mmol), quinolin-8-amine (30 mg, 0.2 mmol) and potassium dicyanoargentate (40 mg, 0.2 mmol) in water–ethanol (4:1 v/v, 20 ml). The mixture was transferred to a Teflon-lined autoclave and heated at 423 K for 48 h. The autoclave was then allowed to cool to ambient temperature. Deep-red crystals of the title compound were collected by filtration, washed with water and dried in air (yield 30%).

Refinement details top

Crystal data, data collection and structure refinement details are summarized in Table 2. Special attention was paid to the accurate orientation for the three cyanide ligands in the asymmetric unit. For each C≡N group, two refinements were carried out with each possible orientation, and the best model was retained on the basis of R₁ and wR₂ factors, and ADP for the C and N sites. For example, wR₂ for all data rises from 8.78% to ca. 9.30% if one cyanide ligand bonded to Ag2 is inverted. No evidence for disordered cyano groups was detected in the difference maps. All C-bonded H atoms were placed in calculated positions and refined as riding atoms, with C—H bond lengths fixed to 0.93 Å. Amino H atoms bonded to N9 and N19 were found in a difference map and refined freely. For all H atoms, isotropic displacement parameters were calculated as U_iso(H) = 1.2U_eq(carrier atom).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: APEX2 and SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS2014/7 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014/7 (Sheldrick, 2015).

Figures top

	Fig. 1. The molecular structure of the title complex, with displacement ellipsoids drawn at the 30% probability level.
	Fig. 2. Part of the crystal structure of the title complex, emphasizing the N—H···N hydrogen bonds (dashed red lines) forming R rings. The green molecule corresponds to the asymmetric unit.

µ-Cyanido-1:2κ²N:C-dicyanido-1κC,2κC-bis(quinolin-8-amine-1κ²N,N')-2-silver(I)-1-silver(II) top

Crystal data top

[Ag₂(CN)₃(C₉H₈N₂)₂]	F(000) = 1140
M_r = 582.15	D_x = 1.845 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 13.5449 (7) Å	Cell parameters from 9889 reflections
b = 6.9385 (3) Å	θ = 3.1–30.7°
c = 22.3824 (11) Å	µ = 1.89 mm⁻¹
β = 94.767 (2)°	T = 293 K
V = 2096.25 (17) Å³	Prism, deep-red
Z = 4	0.27 × 0.23 × 0.18 mm

Data collection top

Bruker APEXII CCD diffractometer	5226 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.021
φ & ω scans	θ_max = 32.2°, θ_min = 4.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −20→17
T_min = 0.615, T_max = 0.754	k = −7→10
27103 measured reflections	l = −33→32
7113 independent reflections

Refinement top

Refinement on F²	0 constraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.034	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.088	w = 1/[σ²(F_o²) + (0.043P)² + 0.5603P] where P = (F_o² + 2F_c²)/3
S = 1.02	(Δ/σ)_max = 0.001
7113 reflections	Δρ_max = 1.70 e Å⁻³
283 parameters	Δρ_min = −0.56 e Å⁻³
0 restraints

Crystal data top

[Ag₂(CN)₃(C₉H₈N₂)₂]	V = 2096.25 (17) Å³
M_r = 582.15	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 13.5449 (7) Å	µ = 1.89 mm⁻¹
b = 6.9385 (3) Å	T = 293 K
c = 22.3824 (11) Å	0.27 × 0.23 × 0.18 mm
β = 94.767 (2)°

Data collection top

Bruker APEXII CCD diffractometer	7113 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	5226 reflections with I > 2σ(I)
T_min = 0.615, T_max = 0.754	R_int = 0.021
27103 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	0 restraints
wR(F²) = 0.088	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	Δρ_max = 1.70 e Å⁻³
7113 reflections	Δρ_min = −0.56 e Å⁻³
283 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ag1	0.66686 (2)	0.78323 (2)	0.41853 (2)	0.03575 (6)
Ag2	0.97403 (2)	0.95903 (4)	0.28877 (2)	0.05800 (8)
N1	0.58984 (15)	0.6944 (3)	0.32264 (9)	0.0372 (4)
C2	0.6314 (2)	0.7024 (4)	0.27131 (12)	0.0487 (6)
H2A	0.7001	0.7094	0.2722	0.058*
C3	0.5762 (3)	0.7006 (4)	0.21569 (13)	0.0593 (8)
H3A	0.6080	0.7002	0.1804	0.071*
C4	0.4768 (3)	0.6994 (4)	0.21363 (13)	0.0584 (8)
H4A	0.4397	0.7024	0.1768	0.070*
C4A	0.4286 (2)	0.6937 (3)	0.26690 (12)	0.0470 (6)
C5	0.3257 (2)	0.6965 (4)	0.26830 (17)	0.0631 (9)
H5A	0.2852	0.7052	0.2327	0.076*
C6	0.2850 (2)	0.6865 (4)	0.32116 (19)	0.0682 (9)
H6A	0.2166	0.6928	0.3218	0.082*
C7	0.3441 (2)	0.6670 (4)	0.37504 (15)	0.0552 (7)
H7A	0.3142	0.6564	0.4109	0.066*
C8	0.44478 (18)	0.6633 (3)	0.37580 (11)	0.0382 (5)
C8A	0.48939 (18)	0.6834 (3)	0.32138 (11)	0.0360 (5)
N9	0.50821 (17)	0.6373 (3)	0.42895 (10)	0.0400 (5)
H9A	0.481 (2)	0.675 (4)	0.4567 (14)	0.048*
H9B	0.525 (2)	0.519 (4)	0.4314 (13)	0.048*
N11	0.74947 (17)	0.7366 (3)	0.51431 (9)	0.0445 (5)
C12	0.7454 (2)	0.8572 (4)	0.55930 (13)	0.0617 (8)
H12A	0.7000	0.9578	0.5554	0.074*
C13	0.8057 (3)	0.8419 (5)	0.61242 (14)	0.0682 (9)
H13A	0.8014	0.9322	0.6428	0.082*
C14	0.8705 (2)	0.6948 (4)	0.61937 (14)	0.0597 (8)
H14A	0.9111	0.6831	0.6548	0.072*
C14A	0.87684 (19)	0.5588 (4)	0.57329 (12)	0.0448 (6)
C15	0.9406 (2)	0.4006 (4)	0.57738 (15)	0.0590 (8)
H15A	0.9829	0.3824	0.6118	0.071*
C16	0.9414 (3)	0.2742 (4)	0.53187 (18)	0.0708 (10)
H16A	0.9836	0.1684	0.5354	0.085*
C17	0.8793 (2)	0.3000 (4)	0.47926 (14)	0.0560 (7)
H17A	0.8815	0.2114	0.4482	0.067*
C18	0.81619 (17)	0.4517 (3)	0.47276 (11)	0.0379 (5)
C18A	0.81318 (16)	0.5856 (3)	0.52035 (10)	0.0362 (5)
N19	0.75194 (17)	0.4838 (3)	0.41939 (10)	0.0404 (5)
H19A	0.716 (2)	0.397 (4)	0.4210 (12)	0.048*
H19B	0.788 (2)	0.478 (4)	0.3873 (14)	0.048*
C20	0.6010 (2)	1.0782 (4)	0.44098 (11)	0.0431 (6)
N21	0.5709 (2)	1.2156 (4)	0.45109 (12)	0.0620 (7)
C22	0.8639 (2)	0.9377 (4)	0.34572 (14)	0.0525 (7)
N23	0.8017 (2)	0.9129 (4)	0.37489 (12)	0.0607 (6)
C24	1.0814 (2)	0.9611 (4)	0.23044 (13)	0.0497 (6)
N25	1.1367 (2)	0.9559 (4)	0.19515 (12)	0.0620 (7)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ag1	0.03820 (10)	0.03710 (10)	0.03135 (10)	0.00115 (7)	−0.00073 (7)	−0.00062 (7)
Ag2	0.04638 (14)	0.07771 (16)	0.05085 (14)	−0.00800 (10)	0.00974 (10)	0.00022 (10)
N1	0.0449 (11)	0.0354 (10)	0.0311 (10)	0.0019 (8)	0.0019 (8)	−0.0006 (7)
C2	0.0625 (17)	0.0462 (14)	0.0379 (14)	0.0028 (12)	0.0082 (12)	−0.0016 (11)
C3	0.101 (3)	0.0448 (15)	0.0322 (14)	0.0020 (15)	0.0083 (15)	−0.0017 (11)
C4	0.096 (3)	0.0372 (14)	0.0383 (15)	0.0027 (14)	−0.0184 (15)	−0.0002 (11)
C4A	0.0630 (17)	0.0279 (11)	0.0464 (15)	0.0007 (10)	−0.0183 (13)	−0.0006 (10)
C5	0.0601 (19)	0.0490 (16)	0.074 (2)	0.0009 (13)	−0.0320 (17)	0.0012 (14)
C6	0.0419 (17)	0.0603 (19)	0.099 (3)	−0.0001 (13)	−0.0157 (18)	0.0021 (17)
C7	0.0449 (15)	0.0506 (14)	0.071 (2)	−0.0012 (12)	0.0079 (14)	0.0014 (14)
C8	0.0390 (13)	0.0296 (10)	0.0455 (14)	0.0001 (9)	−0.0001 (10)	0.0012 (9)
C8A	0.0457 (13)	0.0225 (9)	0.0383 (13)	0.0021 (8)	−0.0057 (10)	−0.0014 (8)
N9	0.0472 (12)	0.0381 (11)	0.0355 (11)	0.0048 (9)	0.0083 (9)	0.0019 (9)
N11	0.0491 (13)	0.0469 (11)	0.0359 (11)	0.0087 (9)	−0.0062 (9)	−0.0054 (9)
C12	0.074 (2)	0.0592 (17)	0.0497 (17)	0.0210 (15)	−0.0114 (15)	−0.0173 (14)
C13	0.089 (2)	0.0686 (19)	0.0438 (17)	0.0094 (18)	−0.0156 (16)	−0.0194 (15)
C14	0.068 (2)	0.0594 (17)	0.0474 (17)	0.0005 (14)	−0.0217 (14)	−0.0051 (13)
C14A	0.0402 (13)	0.0473 (14)	0.0450 (15)	−0.0041 (10)	−0.0074 (11)	0.0028 (11)
C15	0.0513 (17)	0.0565 (16)	0.065 (2)	0.0051 (13)	−0.0196 (14)	0.0039 (15)
C16	0.064 (2)	0.0536 (17)	0.091 (3)	0.0210 (14)	−0.0199 (18)	−0.0047 (17)
C17	0.0556 (17)	0.0464 (15)	0.0643 (19)	0.0098 (12)	−0.0041 (14)	−0.0121 (13)
C18	0.0334 (12)	0.0390 (12)	0.0408 (13)	−0.0025 (9)	0.0003 (10)	0.0000 (9)
C18A	0.0316 (11)	0.0386 (11)	0.0376 (13)	−0.0018 (9)	−0.0010 (9)	0.0017 (9)
N19	0.0422 (12)	0.0432 (11)	0.0359 (11)	−0.0028 (8)	0.0041 (9)	−0.0047 (9)
C20	0.0539 (15)	0.0388 (13)	0.0365 (13)	−0.0039 (11)	0.0025 (11)	0.0045 (10)
N21	0.0785 (19)	0.0514 (14)	0.0581 (16)	0.0082 (13)	0.0184 (14)	0.0060 (12)
C22	0.0526 (17)	0.0500 (15)	0.0553 (18)	−0.0087 (12)	0.0074 (14)	−0.0033 (12)
N23	0.0626 (16)	0.0563 (14)	0.0659 (17)	−0.0120 (12)	0.0221 (13)	−0.0064 (12)
C24	0.0423 (15)	0.0592 (16)	0.0470 (16)	0.0007 (12)	−0.0004 (13)	0.0082 (12)
N25	0.0548 (15)	0.0745 (17)	0.0581 (17)	0.0054 (12)	0.0119 (13)	0.0138 (12)

Geometric parameters (Å, º) top

Ag1—C20	2.305 (3)	N9—H9A	0.79 (3)
Ag1—N23	2.323 (3)	N9—H9B	0.85 (3)
Ag1—N11	2.357 (2)	N11—C12	1.314 (3)
Ag1—N19	2.375 (2)	N11—C18A	1.357 (3)
Ag1—N1	2.3878 (19)	C12—C13	1.389 (4)
Ag1—N9	2.404 (2)	C12—H12A	0.9300
Ag2—C24	2.033 (3)	C13—C14	1.347 (4)
Ag2—C22	2.047 (3)	C13—H13A	0.9300
N1—C2	1.322 (3)	C14—C14A	1.406 (4)
N1—C8A	1.361 (3)	C14—H14A	0.9300
C2—C3	1.398 (4)	C14A—C15	1.395 (4)
C2—H2A	0.9300	C14A—C18A	1.419 (3)
C3—C4	1.343 (5)	C15—C16	1.345 (5)
C3—H3A	0.9300	C15—H15A	0.9300
C4—C4A	1.407 (4)	C16—C17	1.400 (4)
C4—H4A	0.9300	C16—H16A	0.9300
C4A—C5	1.397 (4)	C17—C18	1.357 (3)
C4A—C8A	1.415 (3)	C17—H17A	0.9300
C5—C6	1.347 (5)	C18—C18A	1.417 (3)
C5—H5A	0.9300	C18—N19	1.436 (3)
C6—C7	1.397 (5)	N19—H19A	0.77 (3)
C6—H6A	0.9300	N19—H19B	0.90 (3)
C7—C8	1.363 (4)	C20—N21	1.069 (3)
C7—H7A	0.9300	C22—N23	1.121 (4)
C8—C8A	1.411 (4)	C24—N25	1.133 (4)
C8—N9	1.420 (3)

C20—Ag1—N23	94.56 (9)	C8—N9—Ag1	110.41 (15)
C20—Ag1—N11	94.96 (8)	C8—N9—H9A	109 (2)
N23—Ag1—N11	96.04 (9)	Ag1—N9—H9A	114 (2)
C20—Ag1—N19	166.25 (8)	C8—N9—H9B	108.5 (19)
N23—Ag1—N19	86.81 (9)	Ag1—N9—H9B	100.1 (19)
N11—Ag1—N19	71.29 (7)	H9A—N9—H9B	114 (3)
C20—Ag1—N1	106.09 (8)	C12—N11—C18A	118.8 (2)
N23—Ag1—N1	91.27 (8)	C12—N11—Ag1	124.28 (18)
N11—Ag1—N1	157.10 (7)	C18A—N11—Ag1	116.52 (16)
N19—Ag1—N1	87.54 (7)	N11—C12—C13	123.3 (3)
C20—Ag1—N9	89.30 (9)	N11—C12—H12A	118.4
N23—Ag1—N9	160.78 (9)	C13—C12—H12A	118.4
N11—Ag1—N9	102.39 (8)	C14—C13—C12	119.2 (3)
N19—Ag1—N9	93.89 (8)	C14—C13—H13A	120.4
N1—Ag1—N9	69.59 (7)	C12—C13—H13A	120.4
C24—Ag2—C22	176.05 (11)	C13—C14—C14A	120.2 (3)
C2—N1—C8A	118.8 (2)	C13—C14—H14A	119.9
C2—N1—Ag1	125.78 (18)	C14A—C14—H14A	119.9
C8A—N1—Ag1	113.24 (15)	C15—C14A—C14	123.7 (3)
N1—C2—C3	122.6 (3)	C15—C14A—C18A	119.2 (2)
N1—C2—H2A	118.7	C14—C14A—C18A	117.1 (2)
C3—C2—H2A	118.7	C16—C15—C14A	120.5 (3)
C4—C3—C2	119.4 (3)	C16—C15—H15A	119.8
C4—C3—H3A	120.3	C14A—C15—H15A	119.8
C2—C3—H3A	120.3	C15—C16—C17	120.8 (3)
C3—C4—C4A	120.4 (3)	C15—C16—H16A	119.6
C3—C4—H4A	119.8	C17—C16—H16A	119.6
C4A—C4—H4A	119.8	C18—C17—C16	121.2 (3)
C5—C4A—C4	123.6 (3)	C18—C17—H17A	119.4
C5—C4A—C8A	119.4 (3)	C16—C17—H17A	119.4
C4—C4A—C8A	117.0 (3)	C17—C18—C18A	119.1 (2)
C6—C5—C4A	120.0 (3)	C17—C18—N19	122.9 (2)
C6—C5—H5A	120.0	C18A—C18—N19	118.1 (2)
C4A—C5—H5A	120.0	N11—C18A—C18	119.3 (2)
C5—C6—C7	121.1 (3)	N11—C18A—C14A	121.5 (2)
C5—C6—H6A	119.4	C18—C18A—C14A	119.2 (2)
C7—C6—H6A	119.4	C18—N19—Ag1	113.75 (15)
C8—C7—C6	120.8 (3)	C18—N19—H19A	100 (2)
C8—C7—H7A	119.6	Ag1—N19—H19A	112 (2)
C6—C7—H7A	119.6	C18—N19—H19B	109.0 (19)
C7—C8—C8A	119.2 (2)	Ag1—N19—H19B	108.9 (17)
C7—C8—N9	123.2 (3)	H19A—N19—H19B	113 (3)
C8A—C8—N9	117.6 (2)	N21—C20—Ag1	179.5 (3)
N1—C8A—C8	119.1 (2)	N23—C22—Ag2	174.7 (3)
N1—C8A—C4A	121.6 (2)	C22—N23—Ag1	163.6 (2)
C8—C8A—C4A	119.2 (2)	N25—C24—Ag2	175.2 (3)

C8A—N1—C2—C3	0.2 (3)	C18A—N11—C12—C13	2.2 (5)
Ag1—N1—C2—C3	−161.74 (19)	Ag1—N11—C12—C13	−170.2 (3)
N1—C2—C3—C4	3.0 (4)	N11—C12—C13—C14	−1.4 (6)
C2—C3—C4—C4A	−2.1 (4)	C12—C13—C14—C14A	0.1 (6)
C3—C4—C4A—C5	178.5 (3)	C13—C14—C14A—C15	−178.8 (3)
C3—C4—C4A—C8A	−1.9 (3)	C13—C14—C14A—C18A	0.3 (5)
C4—C4A—C5—C6	178.6 (3)	C14—C14A—C15—C16	178.7 (3)
C8A—C4A—C5—C6	−1.0 (4)	C18A—C14A—C15—C16	−0.4 (5)
C4A—C5—C6—C7	−2.1 (5)	C14A—C15—C16—C17	0.9 (6)
C5—C6—C7—C8	2.0 (5)	C15—C16—C17—C18	−0.6 (5)
C6—C7—C8—C8A	1.3 (4)	C16—C17—C18—C18A	−0.2 (4)
C6—C7—C8—N9	−177.8 (3)	C16—C17—C18—N19	179.5 (3)
C2—N1—C8A—C8	176.2 (2)	C12—N11—C18A—C18	178.3 (3)
Ag1—N1—C8A—C8	−19.6 (2)	Ag1—N11—C18A—C18	−8.7 (3)
C2—N1—C8A—C4A	−4.4 (3)	C12—N11—C18A—C14A	−1.7 (4)
Ag1—N1—C8A—C4A	159.72 (16)	Ag1—N11—C18A—C14A	171.31 (18)
C7—C8—C8A—N1	175.0 (2)	C17—C18—C18A—N11	−179.4 (3)
N9—C8—C8A—N1	−5.8 (3)	N19—C18—C18A—N11	0.9 (3)
C7—C8—C8A—C4A	−4.3 (3)	C17—C18—C18A—C14A	0.6 (4)
N9—C8—C8A—C4A	174.9 (2)	N19—C18—C18A—C14A	−179.2 (2)
C5—C4A—C8A—N1	−175.2 (2)	C15—C14A—C18A—N11	179.7 (3)
C4—C4A—C8A—N1	5.2 (3)	C14—C14A—C18A—N11	0.5 (4)
C5—C4A—C8A—C8	4.2 (3)	C15—C14A—C18A—C18	−0.3 (4)
C4—C4A—C8A—C8	−175.4 (2)	C14—C14A—C18A—C18	−179.5 (2)
C7—C8—N9—Ag1	−153.5 (2)	C17—C18—N19—Ag1	−172.6 (2)
C8A—C8—N9—Ag1	27.4 (2)	C18A—C18—N19—Ag1	7.2 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N9—H9A···N21ⁱ	0.79 (3)	2.36 (3)	3.143 (4)	169 (3)
N9—H9B···N21ⁱⁱ	0.85 (3)	2.23 (3)	3.075 (3)	172 (3)
N19—H19A···N21ⁱⁱ	0.77 (3)	2.48 (3)	3.205 (4)	157 (3)
N19—H19B···N25ⁱⁱⁱ	0.90 (3)	2.19 (3)	3.087 (4)	175 (3)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, y−1, z; (iii) −x+2, y−1/2, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N9—H9A···N21ⁱ	0.79 (3)	2.36 (3)	3.143 (4)	169 (3)
N9—H9B···N21ⁱⁱ	0.85 (3)	2.23 (3)	3.075 (3)	172 (3)
N19—H19A···N21ⁱⁱ	0.77 (3)	2.48 (3)	3.205 (4)	157 (3)
N19—H19B···N25ⁱⁱⁱ	0.90 (3)	2.19 (3)	3.087 (4)	175 (3)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, y−1, z; (iii) −x+2, y−1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	[Ag₂(CN)₃(C₉H₈N₂)₂]
M_r	582.15
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	13.5449 (7), 6.9385 (3), 22.3824 (11)
β (°)	94.767 (2)
V (Å³)	2096.25 (17)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	1.89
Crystal size (mm)	0.27 × 0.23 × 0.18

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Sheldrick, 2003)
T_min, T_max	0.615, 0.754
No. of measured, independent and observed [I > 2σ(I)] reflections	27103, 7113, 5226
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.750

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.088, 1.02
No. of reflections	7113
No. of parameters	283
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	1.70, −0.56

Computer programs: APEX2 (Bruker, 2009), APEX2 and SAINT (Bruker, 2009), SAINT (Bruker, 2009), SHELXS2014/7 (Sheldrick, 2008), SHELXL2014/7 (Sheldrick, 2015), Mercury (Macrae et al., 2008).

Acknowledgements

The authors acknowledge the Algerian Ministry of Higher Education and Scientific Research, the Algerian Directorate General for Scientific Research and Technological Development and Ferhat Abbas Sétif 1 University for financial support.

References

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Volume 71| Part 6| June 2015| Pages 698-701

doi:10.1107/S2056989015009664

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