The magnetic behavior of a complex can provide insights into its geometry; for example, diamagnetic complexes like [Co(NH₃)₆]³⁺ suggest octahedral geometry due to the absence of unpaired electrons.

Werner’s theory couldn’t explain the selective formation of coordination compounds by specific elements, the directional properties of their bonds, and their distinct magnetic and optical features.

Valence Bond Theory (VBT), Crystal Field Theory (CFT), Ligand Field Theory (LFT), and Molecular Orbital Theory (MOT) are among the approaches suggested to elucidate the nature of bonding in coordination compounds.

Metal atoms or ions, influenced by ligands, undergo hybridization of their (n-1)d, ns, np orbitals to produce a set of equivalent orbitals with defined geometries (e.g., octahedral, tetrahedral). These hybridized orbitals then overlap with ligand orbitals to facilitate bonding.

Ligands are ions or molecules bound to the central atom/ion in a coordination entity. They can be simple ions like Cl⁻, small molecules like H₂O or NH₃, or even larger molecules such as proteins. Examples include Cl⁻, H₂O, NH₃, H₂NCH₂CH₂NH₂, ...