Molten acetamide–potassium thiocyanate eutectic: spectroscopy of first-row transition metal compounds in a room temperature melt

Abstract

The eutectic point of the acetamide–potassium thiocyanate system has been redetermined as 26 °C at 26.3 mol% KSCN, though the melting point is temporarily lowered to 16 °C after heating above 50 °C as a result of a reversible structural change. Electronic spectra of Ni^II and Cr^III solutions are reported and indicate octahedral co-ordination, while Co^II solutions have tetrahedral co-ordination, in each case mainly by thiocyanate anions, with both sulphur and nitrogen ligand atoms, and some co-ordinated acetamide. Comparison with molten alkali metal thiocyanate solutions suggests that in these melts also, mixed co-ordination by sulphur and nitrogen occurs. Variation of the absorption bands of the solutions with temperature was also recorded.