The interplay between steric and electronic effects in tuning T 1/2 for the alkyl substituted manganocenes of general formula [Mn(Cp n-R ) 2 ] (n = 1 to 5 and R = Me, i Pr or t Bu) has been analyzed by means of computational studies. That work showed that the ligand field around the Mn II ion can be increased by adding more electron-donor groups, such as methyl, but that bulky substituents, such as iso-propyl or tert-butyl, can have the opposite effect due to the steric hindrance that they introduce in the molecule, which pushes the Cp rings away from the metal center. However, the effect of the functionalization of the cyclopentadienyl ligand with other groups than methyl in order to control the SCO properties of the [Mn(Cp 1-R ) 2 ] family has not been explored.