The hydrogen fluoride solvent system. Part IV. Solutions of mercury(II) cyanide. Evidence for the Hg2(CN)3+ cation
Cryoscopic, conductimetric, and spectroscopic methods have been used to study solutions of Hg(CN)2 in anhydrous HF. It is concluded that mercury(II) cyanide ionises in the following manner (a). The cation Hg2(CN)3+ probably 2Hg(CN)2+ 2HF ⇌ Hg2(CN)3++ HCN + HF2–(a) has a linear cyanide bridged structure [NC–Hg–CN–Hg–CN]+. Further ionisation to give HgCN+ can also occur according to the equation (b). However the HgCN+ ion is not formed in appreciable amounts except in the Hg2(CN)3++ 2HF ⇌ 2HgCN++ HCN + HF2–(b) presence of Lewis acids, e.g., BF3 and AsF5, which precipitate the insoluble salts HgCN+BF4– and HgCN+AsF6–. These salts were isolated and characterised.