Used as a phase-transfer catalyst in organic synthesis, facilitating reactions between reagents in different phases by transferring ions across phase boundaries. Employed in the preparation of coordination compounds and ionic liquids due to its stable cation-anion pair. Acts as a source of tetrachlorocobaltate(II) anion in studies involving cobalt-based magnetic or optical materials. Also utilized in electrochemical applications for its redox-active properties and ionic conductivity.