Chapter 13.2: d orbitals have the same energy in an isolated atom, but split into two sub-levels in a complex ion. The electric field of ligands cause the d orbitals in complex ions to split so that the energy of an electron transition between them corresponds to a photon of visible light.

 Colored complexes  Nuclear charge  Charge density  Oxidation state

 The color absorbed means the complementary color is reflected (so you will see it)  If copper chloride is cyan (blue-green), then red-orange is being absorbed

 In a TM complex, d-sublevel splits when an electric field (or light) is applied  One of the 3d electrons is excited to a higher sub-level  Note: Not same as e- emitting photon when return to ground state

 The difference in energy between the split sublevels  The nuclear charge  Identity of central metal ion  Charge and density of ligand  Geometry of complex ion  Oxidation number of central metal ion (number of d electrons)

 Higher nuclear charge  More strongly interacting with its ligands ▪ Therefore, absorbs light with higher energy  Ex: [Mn(H 2 O) 6 ] 2+ vs [Fe(H 2 O) 6 ] 3+  Mn = lower ENC  absorbs green  show pink  Fe = higher ENC  absorbs blue  show orange

 Charge density: density of charge around the ion  Greater the charge density of the ligand  Greater the split of the d orbitals ▪ Absorbs higher energy light  Spectrochemical series of ligands: separates ligands by energy separation of d orbitals Spectrochemical series is in Section 15 of data booklet

 Oxidation state of metal depends on no. of d e-  More e- means more repulsion of ligand ▪ This means less interaction of metal with ligand  If oxidation number is higher = less interaction  Thus, absorbs a lower energy light Vanadium oxidation state ions 