1798 — Tassaert discovers the first coordination compound: [Co($NH_{3}$)_{6}]$Cl_{3}$ (cobalt(III) hexaammine chloride). Structure not understood for a century.

1893 — Alfred Werner proposes his coordination theory, distinguishing primary valence (ionisable, = oxidation state) from secondary valence (non-ionisable, = coordination number). Werner is awarded the Nobel Prize in Chemistry in 1913.

1920s–1930s — Linus Pauling develops Valence Bond Theory (VBT) as applied to coordination compounds, explaining hybridisation states ($sp^{3}$, d^{2}$$sp^{3}, sp^{3}$$d^{2}). Explains inner vs outer orbital complexes but fails to explain spectra and colour.

1929 — Hans Bethe develops Crystal Field Theory (CFT) for ionic crystals, treating ligands as point charges. Initially applied to ionic lattices.

1940s–1950s — CFT extended to coordination compounds by Van Vleck and others. The spectrochemical series is established empirically — ligands ranked by the magnitude of crystal field splitting they produce.

1951 — Ferrocene [Fe($C_{5}H_{5}$)_{2}] is discovered (Kealy and Pauson), launching organometallic chemistry.

1960s — Ligand Field Theory (LFT) developed — combines CFT with molecular orbital theory to account for covalent bonding in coordination compounds. More rigorous but more complex than pure CFT.

1969 — Cisplatin (cis-[Pt($NH_{3}$)_{2}$Cl_{2}$]) is discovered to have anticancer activity by Barnett Rosenberg; approved as an anticancer drug in 1978. Demonstrates biological relevance of coordination chemistry.

Present — Coordination compounds central to homogeneous catalysis, MRI contrast agents, solar cells (dye-sensitised), and drug delivery systems.