A series of heteroleptic mixed phosphine/alkoxide 3d complexes was designed to evaluate PPh3 as a protecting group, stabilizing the metal coordination sphere prior to O2 exposure, but oxidatively dissociating in the presence of O2 to allow facile O2 reduction by low coordinate metal centers. Complexes of the form [(Ph3P)2M(OC4F9)2] (M = Fe (1), Co (2), Ni (3), Zn (4)) and [(Ph3P)2M(pinF)] (M = Co (8), Ni (9), Zn (10) were prepared, along with related complexes with non-reactive l-donors, [(DME)Fe(OC4F9)2] (5) and [(Ph3PO)2M(OC4F9)2] (M = Fe (6), Ni (7)). Complexes were characterized by UV–vis and NMR spectroscopies, elemental analysis, and single-crystal X-ray diffraction for 1, 3, 6, 7, 8, 9, and 10. The electronic structure of 3 is particularly notable, with ~D4h geometry at room temperature and ~Td at low temperature, as determined by temperature dependent UV–vis and NMR (1H, 31P) spectroscopies. Complexes (M = Fe, Co, Ni) were screened for O2 reactivity to assess the efficacy of PPh3 as a protecting group. Dimeric [Fe2(μ2-O)(OPPh3)2(OC4F9)4] (13) was isolated after O2 reactivity with 1 and characterized as described above. Related Fe complexes 5 and 6 were each combined with O2 to generate intermediate species capable of both stoichiometric oxidase of hydroquinone to benzoquinone and sub-stoichiometric oxygen atom transfer of thioanisole (PhSMe) to methyl phenyl sulfoxide. Fluorinated alkoxide ligand choice influenced O2 reactivity in CoII complexes, as reactivity was only seen in the less sterically hindering pinF–containing complex 8. In the NiII complexes, on the other hand, the particular fluorinated ligand was not a factor in O2 reduction, as 3 and 9 exhibited similar reactivity. Related dimeric compounds [Co2(pinF)2(THF)4)] (11) and [Zn2(pinF)2(THF)2)] (12) were also isolated and characterized.