A series of metallocene thorium complexes with mono- and bis(phosphido) ligands have been investigated with varying hues: (C5Me5)(2)Th(Cl)[P(Mes)(2)] (Mes = mesityl = 2,4,6-(CH3)(3)C6H2; dark red-purple), (C5Me5)(2)Th[P(Mes)(CH3)](2)(dark red-purple), (C5Me5)(2)Th(CH3)[P(Mes)(2)] (dark red-purple), (C5Me5)(2)Th(CH3)[P(Mes)(SiMe3)] (orange), (C5Me5)(2)Th(Cl)-[P(Mes)(SiMe3)] (orange), (C5Me5)(2)Th[P(Mes)(SiMe3)](2)(orange), and (C5Me5)(2)Th[PH(Mes)](2) (pale yellow). While all of these complexes bear a mesityl group on phosphorus, the electronic structure observed differs depending on the other substituent (mesityl, methyl, trimethylsilyl, or hydrogen). This sparked an investigation of the electronic structure of these complexes using( 31)P NMR and electronic absorption spectroscopy in concert with time-dependent density functional theory calculations.