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The combination of transition metal fragments with 90 or 180° angles, viz. cis-a₂M^II (a=amine or a₂=diamine; M=Pt or Pd) and trans-a₂Pt^II or Hg^II, respectively, with (heterocyclic ligands providing 90, 120, or 180° angles leads, either in a self-assembly process or in a stepwise fashion, to cations of versatile shapes and charges. Examples include open boxes, molecular squares, hexagons, triangles and cups. Intermolecular H bonding can assist association of smaller entities. Synthetic and structural aspects as well as physico–chemical properties of selected examples with be discussed.