Earth Alkaline Tetrathiosquarates. II. – Syntheses and Crystal Structures of SrC 4 S 4 ·4 H 2 O and Ba 4 K 2 (C 4 S 4 ) 5 ·16 H 2 O

Concentrated aqueous solutions of strontium chloride and barium chloride, respectively, allow on addition of the potassium salt of tetrathiosquarate, K 2 C 4 S 4 ·H 2 O, the isolation of the earth alkaline salts SrC 4 S 4 ·4 H 2 O ( 1 ) and Ba 4 K 2 (C 4 S 4 ) 5 ·16 H 2 O ( 2 ), both as dark red crystals. The crystal structure determinations ( 1 : orthorhombic, Pnma , a = 8.149(1), b = 12.907(2), c = 10.790(2) Å, Z = 4; 2 : orthorhombic, Pbca , a = 15.875(3), b = 21.325(5), c = 16.119(1) Å, Z = 4) show the presence of C 4 S 4 2− ions with only slightly distorted D 4 h symmetry having average C–C and C–S bond lengths of 1.41Å and 1.681Å for 1 and 1.450Å and 1.657Å for 2 . The structure of 1 contains concatenated edge‐sharing Sr(H 2 O) 6 S 2 polyhedra. The Sr 2+ ions are in eight‐fold coordination with Sr–O distances of 2.50–2.72Å and Sr–S distances of 3.21Å, (C 4 S 4 ) 2− acts as a chelating ligand towards Sr 2+ . The structure is closely related to the previously reported Ca 2+ containing analogue, which is of lower symmetry belonging to the monoclinic crystal system. A supergroup‐subgroup relation between the space groups of both structures is present. The structure of 2 is made up of Ba 2+ and K + ions in eight and nine‐fold coordination by H 2 O molecules and (C 4 S 4 ) 2− ions which act as chelating ligands towards one cation and bridging between two cations. The coordination polyhedra of the cations are connected by common edges and corners in two dimensions to layers which are connected by tetrathiosquarate ions to a three‐dimensional network. The infrared and Raman spectra show bands typical for the molecular building units of the two compounds.