Splitting of d-Orbitals

Complex ions consist of a metal ion surrounded by anions or molecules known as ligands. Unlike most metals, complex ions form dative bonds, rather than the usual ionic bonds. A dative bond is similar to a covalent bond, but rather than forming a bond with one electron from each atom, the bond is created by the donation of a pair of electrons by one atom or ion. Ligands that have these lone pair electrons behave …

…amp;lt;O2- < H2O<NH3 <NO2- <CH3-, C6H5-<CN- <CO For example: If excess ammonia solution was added to a hexaaquacopper(II) solution (cyan), the solution would become tetraamminediaquacopper(II) (dark blue). Since yellow light is of higher light energy that red light, more energy is required to promote an electron in complexes containing ammonia than water.