Mixed halides of mercury (II)

Abstract

The solid-state reactions (i) Hg₂F₂(s)+ Br₂(g), (ii) Hg₂F₂(s)+ I₂(g), (iii) Hg₂Cl₂(s)+ Br₂(g), (iv) Hg₂(CH₃COO)₂(s) + Br₂(g), (v) Hg₂(CH₃COO)₂(s) + I₂(g) and (vi) Hg₂I₂(s)+Br₂(g) have been investigated. Reactions (i)-(v) yield HgFBr, HgFI, HgClBr, Hg(CH₃COO)Br and Hg(CH₃COO)I respectively. In reaction (vi) HgBrI is an intermediate product which subsequently reacts with Br₂(g) to produce HgBr₂(s) and I₂(g). The identity of the reaction product has been confirmed by X-ray powder diffraction data and the thermal stability data is consistant with thermodynamic predictions. It is found that HgFI undergoes photochemical decomposition in CCl₄. The quantum yield was found to be of the order of 3 × 10⁻³ molecules/photon. Results suggest the following equilibria, 2HgFI ⇆^light_dark Hg₂F₂ + I₂. Solid-state kinetics for reactions (i)-(v) were studied. The energies of activation were found to be 17·2, 14·2, 7·2, 8·0 and 6·0 kcal/mole, respectively.