Abstract:
Thermochromic behavior can occur through a number of different mechanisms. Here four compounds are examined. Bis(diethylammonium) tetrachlorocuprate (II) changes color as a result of a geometry change from square planar to distorted tetrahedral. bis(diethylammonium) tetrachloronickelate (II) changes color as a result of a decrease in coordination number from six (octahedral) to four (tetrahedral). Ag2HgI4 and Cu2HgI4 change color as a result of a change in lattice formation from a highly organized tetragonal to a more random tetragonal lattice. The mechanisms proposed by the literature are reinforced by magnetic susceptibility readings, UV-vis, mid IR, and eyeball spectroscopy.