Coordination Compounds — Important Questions

They are ions or molecules bound to the central atom/ion in a coordination entity., They may be simple ions such as Cl− or small molecules such as H2O and NH3., They can be unidentate, didentate, polydentate or ambidentate.

Ligands are the ions or molecules attached to the central atom/ion in a coordination entity. They can be simple ions like Cl− or molecules like H2O and NH3, and they may be classified as unidentate, didentate, polydentate, or ambidentate depending on how they bind. The statement that they always donate through more than one atom is incorrect because many ligands are unidentate.

Ligands are named before the metal, Anionic ligands end in -o, The metal in an anionic complex ends in -ate, Oxidation state is shown in Roman numerals, Cation is always named first

All these are correct IUPAC naming rules: ligands come before metal in naming, anionic ligands end in -o (chloro, cyano), metals in anionic complexes end in -ate (ferrate, chromate), oxidation states use Roman numerals in parentheses, and cations are named first regardless of charge.

Crystal Field theory

Crystal Field Theory explains the color of coordination compounds through d-d electronic transitions. When ligands approach the metal ion, d orbitals split into different energy levels. Light absorption occurs when electrons transition between these split d orbitals, giving rise to color.

t2g and eg

In octahedral crystal field, the five d orbitals split into two sets: t2g (lower energy, containing dxy, dxz, dyz) and eg (higher energy, containing dx2-y2, dz2). The t2g orbitals are directed between the ligands while eg orbitals point directly toward the ligands.