Crystal and molecular structure of bis(tetrasulphur tetraimide)silver(I) perchlorate sesquihydrate

Abstract

The crystal structure of the title compound has been determined by Patterson and Fourier methods and refined by full-matrix least squares to R= 0.064 for 1 895 observed diffractometer data. The crystals are monoclinic, with a= 11.487(5), b= 14.623(6), c= 11.684(5)Å, β= 105.39(6)°, space group P2₁/c, and Z= 4. The structure consists of [Ag(S₄N₄H₄)₂]⁺ cations, ClO₄^– anions, and water molecules, all interconnected by an extensive network of hydrogen bonds. The cation has a sandwich structure with the S₄N₄ crowns arranged so that the sulphur atoms are nearest the cation and there are no Ag–N bonds. The silver ion is displaced sideways from a central position and the S₄N₄H₄ ligands are tilted, with an angle of 20.4° between the two S₄ mean planes. Notwithstanding these distortions, the two ligands can be seen to have adopted a staggered configuration with respect to the two S₄ groups. As a result of the silver-ion positioning, two sulphur atoms from each ligand are closer (2.696–2.792 Å) to the metal than the other two pairs (3.141–3.226 Å) and are arranged so as to produce a distorted tetrahedral metal co-ordination. The bonds between the four nearest sulphur atoms and the metal ion are thus considered to possess significant covalent character. As far as we are aware, this is the first example of a complex of a sulphur imide and the first proven example of donor sulphur rather than donor nitrogen in any sulphur nitride or imide adduct.