The current study concerns the thermochemistry and energetics of organoiron compounds that contain an iron–carbon bond. The main quantities that are discussed are enthalpies of formation and bond energies. The chapter begins with the simplest binary iron carbides and then considers progressively larger neutral and ionic organic ligands. Within the context of small ligands, binding to iron as found in hemes and hemoglobin is discussed. The acidity and basicity of iron‐containing compounds is also included.