Proposed by H. Bethe & Van Bleck(1935) H. Bethe  Van Bleck Used fo r  Firstly used for the   explanation of color and the magnetic properties of crystalline solid. In 1951, several theoretical chemists working independently used crystal field theory to interpret the spectra of transition metal complexes. Principle-  it is based on the principle of electrostatic theory, "the bond energy between two oppositely charged ions q and q' placed at a distance between 'r' with each other is given by the equation  Salient features of CFT The bond between the metal and the ligands is 100% ionic. In the coordination compound the charges are present in metal ions and ligands. Metal act as a positive charge whereas the negative charge is due to the ligands as the point charge in anion or the point dipole in the neutral ligands like water and ammonia. The interaction between the metal ion and ligands is attractive wh...