Synthesis, X‐ray Structures, Spectroscopic and Thermal Characterization of Two New Organic Ammonium Tetrathiotungstates

Abstract

Abstract Two new tetrathiotungstates (pipH 2 )[WS 4 ] ( 1 ) and (trenH 2 )[WS 4 ] · H 2 O ( 2 ) (pip = piperazine and tren = tris(2‐aminoethyl)amine) were synthesized and characterized by elemental analysis, infrared, Raman, UV‐Visible and 1 H NMR spectroscopy, single crystal X‐ray crystallography, and thermoanalysis. In 1 and 2 the amines pip and tren are diprotonated and they are linked to the [WS 4 ] 2− tetrahedra via weak N‐H···S ( 1 , 2 ) and N‐H···O ( 2 ) hydrogen bonds. In 2 the H atoms of the H 2 O molecule have also contacts to S atoms. The strength and number of the S···H interactions affect the W‐S bond lengths and a relatively long W‐S bond of 2.2147(7) Å is observed in 1 while the longest W‐S bond in 2 is 2.1997(6) Å. The different degree of distortion of the [WS 4 ] 2− anions is reflected in the IR and Raman spectra. The compounds decompose upon heating in an inert atmosphere to form amorphous WS 2.1 C 1.2 N 0.3 and WS 2.1 C 3 N 0.8 respectively, and the C and N content of the decomposition products is determined by the C and N content of the amines. In contrast to other tetrathiotungstates, the thermal reaction of both compounds do not proceed via amorphous WS 3 as an intermediate phase. Compound 2 can be reversibly de‐ and re‐hydrated, and the process of re‐hydration proceeds presumably via dissolution‐re‐crystallization mechanism.