Crystal structure of [Ag(NH3)3]2[Ag(NH3)2]2[SnF6]F2, a compound showing argentophilic inter-actions.

Bis[triamminesilver(I)] bis-[diamminesilver(I)] hexa-fluorido-stannate(IV) difluoride, [Ag(NH3)3]2[Ag(NH3)2]2[SnF6]F2, was obtained in the form of colourless crystals from the reaction of CsAgSnF7 in anhydrous ammonia. Two different ammine complexes of silver(I) are present in the structure, i.e. a linear diammine and a T-shaped triammine complex. The ammine silver(I) complexes show Ag⋯Ag distances in the range of argentophilic inter-actions. In the crystal, several N-H⋯F hydrogen bonds are present between the complex cations and the SbF6- and F- anions, leading to the formation of a three-dimensional network.

Chemical context

Metallophilicity, especially argento- and aurophilicity, is a theoretically and experimentally well-established concept, see, for example, the seminal works of Jansen (Jansen, 1987 ▸), Schmidbaur and co-workers (Scherbaum et al., 1988 ▸; Schmidbaur, 1995 ▸; Schmidbaur & Schier, 2012 ▸, 2015 ▸) or Pyykkö and co-workers (Pyykkö & Zhao, 1991 ▸; Pyykkö, 1997 ▸,2004 ▸; Pyykkö et al., 1997 ▸; Pyykkö & Mendizabal, 1997 ▸). We reacted a silver(II) compound, CsAgSnF7, with anhydrous liquid ammonia and observed the reduction of AgII. The preparation conditions and crystal structure of the thus obtained AgI title compound, [Ag(NH3)3]2[Ag(NH3)2]2[SnF6]F2, is reported here. The short Ag⋯Ag distances between the complex cations are in the range of argentophilic inter­actions.

Structural commentary

[Ag(NH3)3]2[Ag(NH3)2]2[SnF6]F2 crystallizes in space group type P21/c. The Sn atom occupies Wyckoff position 2d (site symmetry ), all other atoms reside on general positions 4e. The structure comprises of [Ag(NH3)3]+ and [Ag(NH3)2]+ complex cations as well as F− and [SnF6]2− anions (Fig. 1 ▸). The diamminesilver(I) cation (Ag2) is almost linear with an N—Ag—N angle of 170.93 (7)° and Ag—N distances of 2.1160 (16) and 2.1183 (16) Å. The deviation from linearity is likely to arise from the surrounding, i.e. N—H⋯F hydrogen bonding to adjacent [SnF6]2− and F− anions. This [Ag(NH3)2]+ cation shows a short Ag⋯Ag distance of 3.0611 (2) Å to a neighboring [Ag(NH3)3]+ cation and another slightly longer Ag⋯Ag distance of 3.3282 (2) Å to a second [Ag(NH3)3]+ cation (symmetry code x, −y + , z + ). The triammine silver(I) cation (Ag1) is T-shaped and can be viewed as a linear diammine silver(I) cation to which another ammine ligands is bound at a longer distance. The short Ag—N distances are 2.1434 (16) and 2.1662 (16) Å, and the remote ammine ligand is bound at a distance of 2.5870 (19) Å. The N—Ag—N angle between the shortly bonded ligands is 173.74 (7)°. The deviation of N—Ag—N angles including the remote ammine ligand from 90° [85.44 (6) and 110.82 (6)°] are probably due to hydrogen bonding of the ammine ligands to F atoms of the anions.

Figure 1

The principal building units in the crystal structure of the title compound, showing the F− anion, the [SnF6]2− anion, as well as the argentophilic inter­action (in red) between the [Ag(NH3)2]+ and [Ag(NH3)3]+ cations. Displacement ellipsoids are drawn at the 70% probability level and H atoms are shown with an arbitrary radius. [Symmetry code: (i) −x + 1, −y, −z + 1.]

Supra­molecular features

As a result of the short Ag1⋯Ag2 contacts, corrugated strands of alternating [Ag(NH3)3]+ and [Ag(NH3)2]+ cations occur where the [Ag(NH3)3]+ cations form the kinks which are connected by the [Ag(NH3)2]+ cations. The strands run parallel to the c axis (Fig. 2 ▸). Similar metallophilic inter­actions have been observed in the ammine copper(I) fluoride {[Cu(NH3)3]2[Cu2(NH3)4]}F4·4NH3 (Woidy et al., 2015 ▸). However, the cuprophilic inter­actions are only observed between the diammine copper(I) cations forming linear strands whereas the triammine copper(I) cations do not show such inter­actions.

Figure 2

A section of the crystal structure in a view along [100], showing a corrugated strand of complex cations running along [001]. The argentophilic inter­actions are drawn as red dashed bonds between the AgI atoms and N—H⋯F hydrogen bonds are shown as dashed lines. [SnF6]2− anions are shown as polyhedra to highlight their positions relative to the the kinks of the strand. Displacement ellipsoids are as in Fig. 1 ▸.

In the title structure, the fluoride anions reside above and below the cation strands and connect neighbouring strands via N—H⋯F hydrogen bonds, whereas the [SnF6]2− anions lie on the sides of the strands, also connecting neighbouring ones. The free fluoride ion (F4) is an acceptor of six hydrogen bonds (Fig. 3 ▸). Its coordination environment resembles an octa­hedron with one longer edge. It inter­connects the Ag⋯Ag strands along the a-axis. The [SnF6]2− anion inter­connects four of the Ag⋯Ag strands (Fig. 4 ▸). Four of the six F atoms bonded to the Sn atom are acceptors of four hydrogen bonds (two regular, two bifurcated), the other two F atoms are acceptors of three hydrogen bonds. The diammine silver(I) cations only form regular hydrogen bonds, whereas the triammine silver(I) cations form regular as well as bifurcated hydrogen bonds. The bifurcated hydrogen bonds bridge four edges of each [SnF6]2− octa­hedron. Overall, a rather complex three-dimensional hydrogen-bonded network results (Fig. 5 ▸). Numerical details of the hydrogen-bonding inter­actions are summarized in Table 1 ▸.

Figure 3

A section of the crystal structure of the title compound, showing the N—H⋯F hydrogen bonds (dashed lines) around the free fluoride anion and the bridging of the corrugated Ag⋯Ag strands (red dashed lines). Displacement ellipsoids are as in Fig. 1 ▸. [Symmetry codes: (ii) x, −y + , z + ; (x) 1 + x, y, z; (xi) 1 + x,  − y,  + z; (xii) 1 + x, y, 1 + z.]

Figure 4

A section of the crystal structure, showing the hydrogen bonding towards the [SnF6]2− anion, which is shown as a polyhedron. AgI atoms are inter­connected by Ag⋯Ag inter­actions (red dashed lines) to show the formation of strands. Displacement ellipsoids are as in Fig. 1 ▸.

Figure 5

The crystal structure of the title compound. AgI atoms are inter­connected by argentophilic inter­actions (red dashed lines) to show the formation of strands and [SnF6]2− anions are shown as polyhedra. Displacement ellipsoids are as in Fig. 1 ▸.

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯F4i	0.85 (3)	2.03 (3)	2.884 (2)	178 (2)
N1—H1B⋯F4ii	0.89 (3)	1.96 (3)	2.844 (2)	171 (3)
N1—H1C⋯F3i	0.98 (4)	2.14 (4)	3.057 (2)	156 (3)
N2—H2A⋯F1iii	0.91 (3)	2.43 (3)	3.227 (2)	146 (2)
N2—H2A⋯F3iv	0.91 (3)	2.56 (3)	3.354 (2)	145.4 (19)
N2—H2B⋯F3	0.94 (3)	2.04 (3)	2.961 (2)	167 (3)
N2—H2C⋯F4	0.83 (3)	2.02 (3)	2.849 (2)	172 (3)
N3—H3A⋯F1i	0.88 (3)	2.57 (3)	3.274 (2)	138 (3)
N3—H3A⋯F2v	0.88 (3)	2.42 (3)	3.223 (2)	153 (3)
N3—H3B⋯F3iv	0.79 (3)	2.61 (3)	3.345 (3)	157 (3)
N3—H3C⋯F1vi	0.91 (3)	2.39 (3)	3.279 (3)	167 (3)
N4—H4A⋯F2	0.90 (3)	2.04 (3)	2.930 (2)	170 (2)
N4—H4B⋯F4vii	0.84 (3)	1.97 (3)	2.7955 (19)	171 (3)
N4—H4C⋯F1i	0.79 (3)	2.33 (3)	3.045 (2)	151 (3)
N5—H5A⋯F4	0.96 (3)	1.90 (3)	2.8305 (19)	160 (3)
N5—H5B⋯F4viii	0.95 (3)	1.93 (3)	2.882 (2)	173 (2)
N5—H5C⋯F2ix	0.93 (3)	2.09 (3)	2.999 (2)	163 (3)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) ; (viii) ; (ix) .

Synthesis and crystallization

870 mg of CsAgSnF7 were reacted with approximately 10 ml of anhydrous liquid ammonia at 195 K. Upon contact, the greenish colour of the educt vanished and a white powder was observed. This indicates that AgII was reduced to AgI and ammonia was oxidized to N2. From this white powder, colorless crystals grew within three months of storage at 233 K of which a suitable one was selected for the diffraction experiment. The role of the Cs atoms remains unclear.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. Hydrogen atoms were localized from difference Fourier syntheses and were refined freely.

Table 2

Experimental details

Crystal data
Chemical formula	[Ag(NH3)3]2[Ag(NH3)2]2[SnF6]F2
M r	872.51
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	123
a, b, c (Å)	7.3274 (2), 19.4495 (4), 7.8579 (3)
β (°)	113.205 (4)
V (Å3)	1029.27 (6)
Z	2
Radiation type	Mo Kα
μ (mm−1)	5.01
Crystal size (mm)	0.20 × 0.05 × 0.05
Data collection
Diffractometer	Oxford-Diffraction Xcalibur3
Absorption correction	Multi-scan (CrysAlis RED; Oxford Diffraction, 2008 ▸)
T min, T max	0.602, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	30418, 5731, 4330
R int	0.030
(sin θ/λ)max (Å−1)	0.889
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.020, 0.046, 0.99
No. of reflections	5731
No. of parameters	167
H-atom treatment	All H-atom parameters refined
Δρmax, Δρmin (e Å−3)	1.04, −0.93

Computer programs: CrysAlis CCD and CrysAlis RED (Oxford Diffraction, 2008 ▸), SHELXS97 (Sheldrick, 2008 ▸), SHELXL2016 (Sheldrick, 2015 ▸), SHELXLE (Hübschle et al., 2011 ▸), DIAMOND (Brandenburg, 2012 ▸) and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989016019010/wm5342sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989016019010/wm5342Isup2.hkl

CCDC reference: 1519625

Additional supporting information: crystallographic information; 3D view; checkCIF report

[Ag(NH3)3]2[Ag(NH3)2]2[SnF6]F2	F(000) = 820
Mr = 872.51	Dx = 2.815 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.3274 (2) Å	Cell parameters from 16653 reflections
b = 19.4495 (4) Å	θ = 2.8–39.1°
c = 7.8579 (3) Å	µ = 5.01 mm−1
β = 113.205 (4)°	T = 123 K
V = 1029.27 (6) Å3	Block, colorless
Z = 2	0.20 × 0.05 × 0.05 mm

Oxford-Diffraction Xcalibur3 diffractometer	5731 independent reflections
Radiation source: Enhance (Mo) X-ray Source	4330 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.030
Detector resolution: 16.0238 pixels mm-1	θmax = 39.2°, θmin = 3.0°
phi– and ω–rotation scans	h = −12→13
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008)	k = −34→30
Tmin = 0.602, Tmax = 1.000	l = −13→13
30418 measured reflections

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.020	All H-atom parameters refined
wR(F2) = 0.046	w = 1/[σ2(Fo2) + (0.0215P)2] where P = (Fo2 + 2Fc2)/3
S = 0.99	(Δ/σ)max = 0.002
5731 reflections	Δρmax = 1.04 e Å−3
167 parameters	Δρmin = −0.93 e Å−3
0 restraints	Extinction correction: SHELXL2016 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00277 (14)

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

	x	y	z	Uiso*/Ueq
SN1	0.500000	0.000000	0.500000	0.01140 (3)
F1	0.71015 (17)	0.04893 (6)	0.45645 (18)	0.0254 (3)
F2	0.31983 (17)	0.07728 (6)	0.39037 (17)	0.0232 (2)
F3	0.58561 (19)	0.04104 (7)	0.74794 (16)	0.0274 (3)
AG1	0.16018 (2)	0.12778 (2)	0.95234 (2)	0.01661 (3)
N1	−0.1364 (2)	0.16467 (9)	0.8813 (2)	0.0179 (3)
H1A	−0.170 (4)	0.1789 (14)	0.968 (4)	0.029 (7)*
H1B	−0.171 (4)	0.2005 (14)	0.805 (4)	0.028 (7)*
H1C	−0.222 (5)	0.1286 (19)	0.805 (5)	0.070 (11)*
N2	0.4708 (2)	0.10144 (9)	1.0373 (2)	0.0175 (3)
H2A	0.509 (4)	0.0701 (13)	1.131 (3)	0.021 (6)*
H2B	0.485 (4)	0.0811 (15)	0.935 (4)	0.041 (8)*
H2C	0.557 (5)	0.1316 (16)	1.084 (4)	0.044 (9)*
N3	0.0911 (3)	0.00306 (10)	0.8291 (3)	0.0277 (4)
H3A	−0.031 (5)	−0.0050 (15)	0.751 (5)	0.046 (9)*
H3B	0.149 (5)	−0.0181 (16)	0.920 (5)	0.043 (9)*
H3C	0.133 (5)	−0.0059 (15)	0.737 (4)	0.043 (9)*
AG2	0.23394 (2)	0.22258 (2)	0.67497 (2)	0.01676 (3)
N4	0.0292 (3)	0.15407 (9)	0.4859 (2)	0.0196 (3)
H4A	0.111 (4)	0.1257 (14)	0.459 (4)	0.033 (7)*
H4B	−0.052 (4)	0.1757 (14)	0.396 (4)	0.034 (7)*
H4C	−0.034 (4)	0.1288 (15)	0.520 (4)	0.033 (8)*
N5	0.4733 (2)	0.28292 (9)	0.8539 (2)	0.0167 (3)
H5A	0.543 (4)	0.2617 (14)	0.973 (4)	0.033 (7)*
H5B	0.562 (4)	0.2883 (12)	0.793 (3)	0.020 (6)*
H5C	0.439 (5)	0.3248 (17)	0.891 (4)	0.052 (9)*
F4	0.74284 (16)	0.21290 (6)	1.16824 (14)	0.0177 (2)

	U11	U22	U33	U12	U13	U23
SN1	0.01283 (6)	0.01077 (7)	0.01170 (7)	−0.00057 (5)	0.00600 (5)	−0.00041 (5)
F1	0.0194 (5)	0.0291 (7)	0.0314 (6)	−0.0056 (5)	0.0139 (5)	0.0066 (5)
F2	0.0207 (5)	0.0175 (5)	0.0319 (6)	0.0053 (4)	0.0110 (5)	0.0065 (5)
F3	0.0329 (6)	0.0314 (7)	0.0179 (5)	−0.0038 (5)	0.0098 (5)	−0.0095 (5)
AG1	0.01565 (5)	0.01867 (7)	0.01611 (6)	0.00126 (5)	0.00689 (4)	0.00184 (5)
N1	0.0179 (7)	0.0166 (7)	0.0183 (7)	0.0021 (6)	0.0061 (6)	0.0005 (6)
N2	0.0175 (6)	0.0178 (7)	0.0160 (7)	0.0000 (6)	0.0053 (5)	−0.0007 (6)
N3	0.0206 (8)	0.0236 (9)	0.0346 (10)	0.0001 (7)	0.0063 (8)	−0.0068 (8)
AG2	0.01614 (6)	0.01801 (7)	0.01510 (6)	−0.00111 (5)	0.00505 (4)	0.00066 (4)
N4	0.0184 (7)	0.0174 (8)	0.0194 (7)	−0.0010 (6)	0.0035 (6)	0.0012 (6)
N5	0.0169 (6)	0.0173 (7)	0.0161 (7)	0.0003 (5)	0.0066 (5)	0.0011 (5)
F4	0.0176 (5)	0.0200 (5)	0.0143 (5)	−0.0003 (4)	0.0051 (4)	−0.0015 (4)

Sn1—F1i	1.9518 (11)	N2—H2A	0.91 (3)
Sn1—F1	1.9518 (11)	N2—H2B	0.94 (3)
Sn1—F2	1.9617 (11)	N2—H2C	0.83 (3)
Sn1—F2i	1.9617 (11)	N3—H3A	0.88 (3)
Sn1—F3i	1.9655 (11)	N3—H3B	0.79 (3)
Sn1—F3	1.9656 (11)	N3—H3C	0.91 (3)
Ag1—N1	2.1434 (16)	Ag2—N4	2.1160 (16)
Ag1—N2	2.1662 (16)	Ag2—N5	2.1183 (16)
Ag1—N3	2.5870 (19)	N4—H4A	0.90 (3)
Ag1—Ag2	3.0611 (2)	N4—H4B	0.84 (3)
Ag1—Ag2ii	3.3283 (2)	N4—H4C	0.79 (3)
N1—H1A	0.85 (3)	N5—H5A	0.96 (3)
N1—H1B	0.89 (3)	N5—H5B	0.95 (3)
N1—H1C	0.98 (4)	N5—H5C	0.93 (3)
F1i—Sn1—F1	180.0	Ag1—N2—H2A	110.8 (15)
F1i—Sn1—F2	90.56 (5)	Ag1—N2—H2B	107.2 (17)
F1—Sn1—F2	89.44 (5)	H2A—N2—H2B	108 (2)
F1i—Sn1—F2i	89.44 (5)	Ag1—N2—H2C	119 (2)
F1—Sn1—F2i	90.56 (5)	H2A—N2—H2C	100 (2)
F2—Sn1—F2i	180.0	H2B—N2—H2C	111 (3)
F1i—Sn1—F3i	90.58 (6)	Ag1—N3—H3A	115 (2)
F1—Sn1—F3i	89.42 (6)	Ag1—N3—H3B	101 (2)
F2—Sn1—F3i	88.80 (5)	H3A—N3—H3B	126 (3)
F2i—Sn1—F3i	91.19 (5)	Ag1—N3—H3C	113.7 (19)
F1i—Sn1—F3	89.42 (6)	H3A—N3—H3C	89 (3)
F1—Sn1—F3	90.58 (6)	H3B—N3—H3C	113 (3)
F2—Sn1—F3	91.19 (5)	N4—Ag2—N5	170.93 (7)
F2i—Sn1—F3	88.81 (5)	N4—Ag2—Ag1	81.11 (5)
F3i—Sn1—F3	180.0	N5—Ag2—Ag1	101.15 (5)
N1—Ag1—N2	173.74 (7)	N4—Ag2—Ag1iii	104.96 (5)
N1—Ag1—N3	100.82 (6)	N5—Ag2—Ag1iii	77.58 (4)
N2—Ag1—N3	85.44 (6)	Ag1—Ag2—Ag1iii	149.685 (7)
N1—Ag1—Ag2	93.35 (5)	Ag2—N4—H4A	101.3 (17)
N2—Ag1—Ag2	84.44 (5)	Ag2—N4—H4B	110.4 (19)
N3—Ag1—Ag2	111.20 (6)	H4A—N4—H4B	115 (3)
N1—Ag1—Ag2ii	77.42 (5)	Ag2—N4—H4C	120 (2)
N2—Ag1—Ag2ii	96.40 (5)	H4A—N4—H4C	104 (3)
N3—Ag1—Ag2ii	169.75 (6)	H4B—N4—H4C	107 (3)
Ag2—Ag1—Ag2ii	79.041 (4)	Ag2—N5—H5A	113.0 (16)
Ag1—N1—H1A	118.6 (17)	Ag2—N5—H5B	106.2 (14)
Ag1—N1—H1B	115.3 (18)	H5A—N5—H5B	109 (2)
H1A—N1—H1B	101 (2)	Ag2—N5—H5C	115.7 (19)
Ag1—N1—H1C	105 (2)	H5A—N5—H5C	100 (2)
H1A—N1—H1C	114 (3)	H5B—N5—H5C	112 (2)
H1B—N1—H1C	102 (3)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···F4iv	0.85 (3)	2.03 (3)	2.884 (2)	178 (2)
N1—H1B···F4v	0.89 (3)	1.96 (3)	2.844 (2)	171 (3)
N1—H1C···F3iv	0.98 (4)	2.14 (4)	3.057 (2)	156 (3)
N2—H2A···F1vi	0.91 (3)	2.43 (3)	3.227 (2)	146 (2)
N2—H2A···F3vii	0.91 (3)	2.56 (3)	3.354 (2)	145.4 (19)
N2—H2B···F3	0.94 (3)	2.04 (3)	2.961 (2)	167 (3)
N2—H2C···F4	0.83 (3)	2.02 (3)	2.849 (2)	172 (3)
N3—H3A···F1iv	0.88 (3)	2.57 (3)	3.274 (2)	138 (3)
N3—H3A···F2viii	0.88 (3)	2.42 (3)	3.223 (2)	153 (3)
N3—H3B···F3vii	0.79 (3)	2.61 (3)	3.345 (3)	157 (3)
N3—H3C···F1i	0.91 (3)	2.39 (3)	3.279 (3)	167 (3)
N4—H4A···F2	0.90 (3)	2.04 (3)	2.930 (2)	170 (2)
N4—H4B···F4ix	0.84 (3)	1.97 (3)	2.7955 (19)	171 (3)
N4—H4C···F1iv	0.79 (3)	2.33 (3)	3.045 (2)	151 (3)
N5—H5A···F4	0.96 (3)	1.90 (3)	2.8305 (19)	160 (3)
N5—H5B···F4iii	0.95 (3)	1.93 (3)	2.882 (2)	173 (2)
N5—H5C···F2ii	0.93 (3)	2.09 (3)	2.999 (2)	163 (3)