Synthesis, properties and structural characterization of 4-(2-ammonioethyl)piperazin-1-ium tetrasulfidotungstate hemihydrate and 1-ethylpiperazinediium tetrasulfidotungstate

摘要

The reaction of ammonium tetrasulfidotungstate with 2-piperazin-1-ylethanamine or 1-ethylpiperazine results in the formation of 4-(2-ammonioethyl)piperazin-1-ium tetrasulfidotungstate hemihydrate (C6H17N3)[WS4]H2O 1 or 1-ethylpiperazinediium tetrasulfidotungstate (C6H16N2)[WS4] 2. The hemihydrate 1 can be dehydrated to the anhydrous compound (C6H17N3)[WS4] 1a, which can be rehydrated to 1.Both 1 and 2 decompose to amorphous carbon containing tungsten disulphide. Compound 1 crystallizes in the centrosymmetric monoclinic space group C2/c, while compound 2 crystallizes in the centrosymmetric orthorhombic space group Pbca. The structures of 1 and 2 consist of a slightly distorted tetrahedral [WS4]2 anion and 4-(2-ammonioethyl)piperazin-1-ium (1) or 1-ethylpiperazinediium dication (2) and additionally a lattice water in 1. In the crystal structure of 1 and 2 the organic cation and the [WS4]2 anion are linked to each other via several weak N–H S and C–H S bonding interactions. The lattice water serves as a link between pairs of cations and pairs of anions with the aid of O–H S and N– H O interactions in compound 1.