A spectrochemical series
is a list of ligands
ordered on ligand strength and a list of metal ions based on oxidation number, group and its identity. In crystal field theory
, ligands modify the difference in energy between the d orbitals (Δ - ligand-field splitting parameter
, or crystal-field splitting parameter
), what is mainly reflected in differences in color of similar metal-ligand complexes.
A partial spectrochemical series listing of ligands from small Δ to large Δ:
I− < Br− < S2− < SCN− < Cl− < NO3− < N3− < F− < OH− < C2O42− ≈ H2O < NCS− < CH3CN < py (pyridine) < NH3 < en (ethylenediamine) < bipy (2,2'-bipyridine) < phen (1,10-phenanthroline) < NO2− < PPh3 < CN− ≈ CO
(for a table, see the ligand page)
- Zumdahl, Steven S. Chemical Principles Fifth Edition. Boston: Houghton Mifflin Company, 2005. 550-551,957-964.
- D. F. Shriver and P. W. Atkins Inorganic Chemistry 3rd edition, Oxford University Press, 2001. Pages: 227-236.