New anionic copper(I) dihalide cyclic guanidinate compounds with H-bonded chelating guanidinium cations

Two new copper(I) dihalide cyclic guanidine salts have been synthesized and characterized structurally, (H2hpp) [(Hhpp)CuCl2], 1 and (H2hpp) [(Hhpp)CuBr2], 2, where Hhpp = (1,3,4,6,7,8-hexahydropyrimido[1,2-a]pyrimidine). Both compounds are isomorphous, crystallizing in the monoclinic space group P2(1)/c. They exhibit the very unusual feature of a trigonal planar copper(I) center tri-coordinated to a neutral cyclic guanidine with two halides in an anion and a cyclic guanidinium cation H-bonded as a chelate to the halides.