Single crystals of (C2H2N2S3)2Bi(SCN)3 have been prepared from solution and its structure has been determined. (C2H2N2S3)2-Bi(SCN)3 is monoclinic, space grouip C2/c, a = 6.730(4), b = 13.285(4), c = 20.679(4) Å, β = 96.92(5)°, Z = 4. Four sites of the strongly distorted tetragonal antiprism forming the coordination polyhedron of the Bi atom are occupied by S and N atoms of two isoperthiocyanic acid molecules (isoperthiocyanic acid: 5-amino-3-thione-1,2,4-dithiazole). The C2N2S3 disubstituted five membered ring units of the isoperthiocyanic acid molecules are planar.
The other four sites of the coordination polyhedron are occupied by S and N atoms of thiocyanate ions. Two of them form bonds via S to the Bi atom. A third thiocyanate group acts as a bidentate ligand, connecting neighbouring Bi atoms. These ambidently bridging thiocyanate ions are disordered, thus leading to infinite chains made up of equal numbers of – Bi – S – C – N – Bi′ – and – Bi – N – C – S – Bi′ – units, running nearly parallel to the crystallographic a-axis. The Bi – S distances range form 2.814(3) to 2.919(2) Å, the Bi – N distances are 2.695(6) Å for the binding N atom of the isoperthiocyanic acid molecule and 2.66(2) Å for the N atom of the disordered bridging thiocyanate ion, respectively. A possible location of the Bi(III) lone pair is briefly discussed.