Charge-transfer band

[1] CT absorptions bands are intense and often lie in the ultraviolet or visible portion of the spectrum.

If the transfer occurs from the MO with ligand-like character to the metal-like one, the transition is called a ligand-to-metal charge-transfer (LMCT).

If the electronic charge shifts from the MO with metal-like character to the ligand-like one, the band is called a metal-to-ligand charge-transfer (MLCT).

This coloration is assigned to LMCT, involving transfer of nonbonding electrons on the oxo ligands to empty d-levels on the metal.

Complexes of bipyridine, phenanthroline, and related unsaturated heterocycles often exhibit strong C-T bands.

[5][6] Intervalence charge transfer (IVCT) is a type of charge-transfer band that is associated with mixed-valence compounds.

The intense color of tris(bipyridine)ruthenium(II) arises from a metal-to-ligand charge-transfer band.
Sample of sodium dichromate . Its orange color arises from LMCT bands, involving transfer of electron from an oxide-dominated state to a metal-dominated state.
Absorption spectrum of an aqueous solution of potassium permanganate, showing a vibronic fine structure in the LMCT band.
Prussian blue is intensely blue owing to an intervalence charge transfer band.