What factors determine the sequence of ligands in the spectro chemical series

Before examining the specific factors determining the Spectrochemical Series, it should be noted that the Spectrochemical series in not an absolute ordering of ligands. The observed order in the series varies somewhat from one complex to another. The identity and oxidation state of the metal and the number and identities of the other ligands play a role in establishing the sequence for a particular class of complexes. The order of ligands shown above represents a general trend, but do not be surprised if you find another source presenting a Spectrochemical Series with a somewhat different sequence of ligands.