Ionic metal hydrides are compounds formed when metals react with hydrogen, resulting in a structure where hydrogen ions (H⁻) bond with metal cations. These hydrides typically consist of alkali and alkaline earth metals, such as sodium or calcium, which donate electrons to hydrogen, creating a stable ionic bond. These compounds are often solid at room temperature and can be used in various applications, including hydrogen storage and as reducing agents in chemical reactions. Ionic metal hydrides can release hydrogen gas when heated or reacted with water, making them important in energy-related technologies.