Poly[[{μ4-2,2′-[butane-1,4-diylbis(sulfanediyl)]bis(1,3,4-thiadiazole)}silver(I)] perchlorate sesquihydrate]

In the polymeric title compound, {[Ag(C8H10N4S4)]ClO4·1.5H2O}n, the AgI atom has a slightly distorted trigonal-planar coordination geometry provided by three N-atom donors from the thiadiazole rings of three symmetry-related 2,2′-[butane-1,4-diylbis(sulfanediyl)]bis(1,3,4-thiadiazole) ligands. Centrosymmetrically related AgI atoms are bridged by the N–N fragments of rings, forming six-membered dinuclear metallacycles, which are further linked by the alkyl spacers of the thiadiazole ligands into a layer network extending parallel to (0-21). The crystal structure is stabilized by intermolecular O—H⋯O hydrogen bonds. The O atoms of the perchlorate anion and one water molecule are disordered over two sets of sites with refined occupancy ratios of 0.640 (6):0.360 (6) and 0.663 (11):0.337 (11), respectively. The second water molecule shows half-occupancy.

In the polymeric title compound, {[Ag(C 8 H 10 N 4 S 4 )]ClO 4 Á-1.5H 2 O} n , the Ag I atom has a slightly distorted trigonal-planar coordination geometry provided by three N-atom donors from the thiadiazole rings of three symmetry-related 2,2 0 -[butane-1,4-diylbis(sulfanediyl)]bis(1,3,4-thiadiazole) ligands. Centrosymmetrically related Ag I atoms are bridged by the N-N fragments of rings, forming six-membered dinuclear metallacycles, which are further linked by the alkyl spacers of the thiadiazole ligands into a layer network extending parallel to (021). The crystal structure is stabilized by intermolecular O-HÁ Á ÁO hydrogen bonds. The O atoms of the perchlorate anion and one water molecule are disordered over two sets of sites with refined occupancy ratios of 0.640 (6):0.360 (6) and 0.663 (11):0.337 (11), respectively. The second water molecule shows half-occupancy.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RZ2753). During the last decade, a great effort has been devoted to designing ligands capable of enforcing close metal contacts during the process of assembly or crystallization to form polynuclear complexes and coordination polymers, owing to these complexes are expected to produce specific structures, properties and reactivities, not found for mononuclear complexes. In particular, N,N′-linkage ligands such as 1,2-diazines, 1,2-diazoles, 1,2,4-triazoles and 1,3,4-thiadiazole are very versatile ligands that are able to bridge a wide range of intermetallic separations through two close adjacent N donors (Yu et al., 2006;Wang & Ma, 2007).
In the title compound ( Fig. 1), the Ag metal is coordinated by three N donors from thiadiazole rings of three distinct 2,2′-(butane-1,4-diyldithio)-bis(1,3,4-thiadiazole) ligands in a slightly distorted trigonal planar coordination geometry, with the metal protruding 0.0172 (15) Å from the N 3 coordination plane. The Ag-N bond distances fall in the range 2.232 (8)-2.311 (9) Å. Centrosymmetrically related Ag metals are doubly bridged by the N-N fragments of thiadiazole rings of two distinct ligands to form six-membered dinuclear metallacycles. The Ag···Ag separation within the rings is 3.722 (4) Å, which is longer than the summed van der Waals radii of two free Ag ions (3.44 Å). The six-membered rings are linked by the alkyl spacers of the ligand into a two-dimensional layer network extending parallel to the (0 -2 1) plane ( Fig. 2). Each Ag metal in the layer shows weak interactions with one S atom from an adjacent layer (Ag···S separation of 3.116 (5) Å), and with the oxygen atoms of the disordered ClO4anion, the shortest Ag···O separation being 2.816 (8) Å.
The crystal structure is enforced by intermolecular O-H···O hydrogen bonds (Table 1).

Experimental
The reaction of bis[2,2′-(butane-1,4-diyldithio)-bis(1,3,4-thiadiazole)] (0.1 mmol) with AgCl0 4 (0.1 mmol) in MeOH (10 mL) for a few minutes afforded a light white solid, which was filtered, washed with acetone, and dried in air. Single crystals of the title compound suitable for X-ray analysis were obtained by slow diffusion of Et 2 O into an acetonitrile solution of the solid.

Refinement
The oxygen atoms of the perchlorate anion and the water molecule including the O5 oxygen atoms are disordered over two sets of sites with refined site occupancy ratios of 0.640 (6):0.360 (6) and 0.663 (11):0.337 (11) respectively. The anisotropic displacement parameters for paired components of the disordered atoms were constrained to be equivalent and approximately isotropic by the EADP and ISOR commands in SHELXL-97 (Sheldrick, 2008). Water H atoms were located in a difference Fourier map and allowed to ride on the parent oxygen atoms, with O-H = 0.85 Å and with U iso (H) = 1.5 U eq (O). All other H atoms were positioned geometrically and refined as riding, with C-H = 0.93-0.97 Å and U iso (H) = 1.2U eq (C).

Figure 1
The asymmetric unit of the title compound, with displacement ellipsoids drawn at the 30% probability level. Hydrogen atoms are omitted.

Poly[[{µ 4 -2,2′-[butane-1,4-diylbis(sulfanediyl)]bis(1,3,4-thiadiazole)}silver(I)] perchlorate sesquihydrate]
Crystal data [Ag(C 8  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.64 e Å −3 Δρ min = −0.75 e Å −3 Special details 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. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and Rfactors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (