context: Hybrid organic–inorganic crystals are unique materials that have been attracting increasing interest in the last few years due to their physical properties and potential applications in different fields, such as photovoltaics, lithium batteries, and photomechanic materials, between others. Among these applications, the development of high conductivity solid state electrolytes for fuel cells, batteries and solar cells is one of the most explored areas, in comparison with the polymers electrolytes that generally show low conductivity. In this sense, they are comparable with the classical ceramic conductors, such as doped lithium titanium phosphate, that allows fast ion transport. However, these materials present the considerable disadvantage of fragility and, in some cases, more importantly toxicity. In order to overcome this problem, a new type of materials have been proposed: the plastic hybrid materials. Although plastic crystals were described in the 60's, there is no rule to predict which cation and anion combinations will yield plastic crystalline materials and which will form salts that melt before any rotator phase is achieved. It deserves to be noted that a plastic crystal has a long-range structural order but short-range disorder, which is typically due to the occurrence of rotational motions of the constituents. This plastic phase can be seen as a mesophase between the solid and liquid phases that is often found in molecules with globular structures. This means that they are symmetrical around their center (CH4, CCl4, NH4 pentaerythritol, etc.); or they make a sphere by rotation around an axis (cyclohexane, camphor, etc.). The combination of two or more units to form hybrid materials can be desirable to enhance the multifunctionality of the system, for example doping plastic crystalline phases with a lithium imide salt for application as solid electrolytes in lithium batteries. An alternative is to combine the physical properties by tuning different constituents: ferroelectricity from polar molecules and long-range magnetic order from magnetic anions.