A hemicucurbituril is a macrocycle composed of alternating methylene bridges (-CH2- units) and N-substituted ethylene urea units. Hemicucurbit[6]uril is a hexamer. This compound closely resembles cucurbituril cut in half along the equator and the chemistry is also similar. The ethylene urea units also alternate with the carbonyl groups assuming alternating up and down positions. For this reason this compound contrary to cucurbituril is unable to form inclusion compounds with metal ions.