Synthesis and structures of the first triiodoarsenate(III) anion, EtAsI3−, and zwitterions, (HPy)2As2I6

The first examples of triiodoarsenates(III) have been synthesized from water solutions and are structurally characterized. Different anionic species, [RAsI3]−, have different tendencies to coordinate to one or two more I atoms of neighboring anions, remain as such, or even exchange one I− anion for other anions. This behaviour means that the bonding of As to the extra iodides is rather weak and largely depends on the crystal packing.