Gold oxidative dissolution by (thioamide)–I2adducts

Francesco Isaia, M. Carla Aragoni, Massimiliano Arca, Claudia Caltagirone, Francesco Demartin, Alessandra Garau, Vito Lippolis
2013 Dalton Transactions  
Elemental gold powder is easily oxidised under mild reaction conditions with 1 : 1 I 2 -adducts of the thioamides 3-methyl-benzothiazole-2-thione (mbtt) and 1-methyl-1H-benzimidazole-2(3H)-thione (mbit) with separation of the ionic complexes [Au I (mbtt) 2 ]I 3 (1) and [(mtbiH) 2 ](AuI 4 )I 3 (2) [mtbiH = the imido protonated form of 2-(methylthio)benzimidazole] (gold oxidation yield >78% and 45%, respectively). The X-ray crystal structure of 1 shows the Au(I) centre linearly bound by two
more » ... bound by two neutral ligands via the sulphur atom, whereas the X-ray crystal structure of 2 shows the Au(III) centre surrounded by four iodides in a square-planar arrangement. The oxidising/complexing properties of the mbtt·I 2 and mbit·I 2 adducts were interpreted considering the S-donor to I 2 interaction that leads to a charge separation between the I b and I t iodine atoms in the fragment S-I b -I t . The oxidation of gold in a non-aqueous solvent by thioamide-I 2 adducts could be a promising alternative process to the numerous hydrometallurgical ones for the recovery of gold from secondary sources.
doi:10.1039/c2dt31855e pmid:23080271 fatcat:37qwqp54y5cp7ixzd7mnvvsjxy