Three-co-ordinate mercury complex: photochromism and molecular structure of phenylmercury(II) dithizonate

Abstract

Solutions in organic solvents of 1 : 1 complexes between organomercury(II) cations and dithizone (and its p-tolyl analogue) undergo reversible photo-isomerisation (yellow ⇌ blue) at conveniently measurable rates; the structure of the crystalline yellow form of phenylmercury(II) dithizonate involves irregular three-co-ordination about the mercury atom, that of the blue form being deduced from spectroscopic measurements on irradiated solutions.