Definitions

spectrochemical

spectrochemical analysis

Any of a group of chemical analysis methods that depend on measurement of the wavelength and intensity of electromagnetic radiation. It is used chiefly to determine the arrangement of atoms and electrons in molecules on the basis of the amounts of energy absorbed during changes in their structure or motion. In more common usage, it usually refers to ultraviolet (UV) and visible emission spectroscopy or to UV, visible, and infrared (IR) absorption spectrophotometry.

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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)

See also

References

  • 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.

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