In tetrahedral complexes, one s and three p orbitals undergo hybridization to form four equivalent orbitals arranged tetrahedrally. This hybridization is demonstrated in [NiCl₄]²⁻, where nickel is in the +2 oxidation state.

[Co(NH₃)₆]³⁺ is an inner orbital or low spin complex, using the inner d orbital (3d) in hybridization, while the paramagnetic complex [CoF₆]³⁻ is an outer orbital or high spin complex, utilizing the outer d orbital (4d) in hybridization.

The complex utilizes inner orbital (3d) hybridization, forming six pairs of electrons from NH₃ ligands in octahedral geometry, resulting in diamagnetism due to the absence of unpaired electrons.

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.

Linkage isomerism occurs in complexes with ambidentate ligands. For instance, thiocyanate ligand (NCS⁻) can bind through nitrogen (M–NCS) or sulphur (M–SCN), illustrated by complexes like [Co(NH₃)₅(NO₂)]Cl₂.

Coordination isomerism involves the interchange of ligands between cationic and anionic entities. In [Co(NH₃)₆][Cr(CN)₆], NH₃ binds to Co³⁺ and CN⁻ to Cr³⁺. In its coordination isomer [Cr(NH₃)₆][Co(CN)₆], the ligand binding arrangement switches.

Ionisation isomerism occurs when the counter ion in a complex salt becomes a ligand. In [Co(NH₃)₅(SO₄)]Br, SO₄ displaces a ligand, while in [Co(NH₃)₅Br]SO₄, Br⁻ becomes the ligand. This is similar to ‘hydrate isomerism’ when water is involved as a solvent.