The syntheses, crystal structures and magnetochemical characterization are reported for two novel high-valent manganese complexes, (NMe4)2(Mn3O(PNH)3(PN)3) (1) and, (NH4)[Mn7(PN)6(PNH)2(MeO)2(O)2(CMe3CH2CO2)2] (2) incorporating the anion of 4,5-Bis(hydroxymethyl)-2-methylpyridin-3-ol. Complexes were characterized by elemental and thermogravimetric analyses, FT-IR spectroscopy, and single-crystal X-ray diffraction studies. Variable temperature, solid-state direct current (dc) magnetization studies were carried out on both the complexes 1 and 2 in the 5.0–315 K range, and they established that both complexes to have ground state spin values of S = 5.