Alkali-metal nickelates are a class of highly reactive heterobimetallic complexes derived from Ni(0)-olefins and polar organo-alkali-metal reagents. First reported over 50 years ago, it is only in recent years that these overlooked complexes have found formidable roles in sustainable catalysis and beyond. In this article, we will showcase the emerging catalytic applications of lithium nickelates and discuss the mechanisms by which these heterobimetallic complexes facilitate challenging cross-coupling reactions. We will also review the unique structure and bonding of alkali-metal nickelates, as interrogated by X-ray crystallography and complementary bonding analysis, and finally explore the diverse coordination and co-complexation chemistry of these heterobimetallic complexes.