Abstract The first crystalline adducts of a colorformer and coreactants have been synthesized. Crystal Violet Lactone (CVL) reacted with zinc and cadmium iodide, respectively, in acetone solution to form well defined complexes. 13C NMR, X-ray and crystallographic data have been collected on these complexes. They indicated an ionic structure of [2 CVL·3ZnI 2- acetone] with a Zn 2I 3-moiety rigidly held in place by two encompassing symmetrically situated carboxylate units. A polymeric structure was found for [CVL·3CdI 2· 1 2 acetone]. The CVL part with its open carboxylate structure is embedded in a carrier matrix built of cadmium and of iodine atoms, forming alternately six- and four-membered rings which are linked with each other in a spiro- arrangement. Intercalated acetone molecules were found to be a prerequisite for the formation of single crystals.