Two-dimensional metal-halide perovskites (2D MHPs) have recently attracted great attention for application as light-absorbing and/or light-emitting materials, or as passivation layer on top of their 3D counterpart. The inherently layered nature of 2D MHPs with A2BX4 chemical structure opens a tremendous construction kit made of A-site cations of various chemical building blocks, while the B-and X-site typically stick with traditional metal (B=Pb; Sn) and halide ions (X=I, Br, Cl), respectively. While the optoelectronic properties are typically controlled by the inorganic scaffold, appropriate A-site cation engineering tailors MHPs stability and may modulate band alignment and its excitonic properties. A-site cations can be distinguished by their charge, with monoammonium and diammonium cations being of most relevance for design of layered 2D MHPs. While a large variety of monoammonium cations has already been demonstrated, diammonium cations as organic spacers in 2D MHPs are systematically underexplored. Being ditopic ligands, such cations can directly interact with two separate inorganic layers. As for monoammonium cations, both linear and cyclic cations have been considered recently, suggesting a wide structural variability in diammonium-based 2D MHPs. However, ditopic organic cations do not always lead to the formation of a layered perovskite structure but may also give rise to other topologies.