The bis-pyrazolato pyridine complex LCo(PEt3)(2) serves as a masked form of three-coordinate Co-II and shows diverse reactivity in its reaction with several potential outer sphere oxidants and oxygen atom transfer reagents. N-Methylmorpholine N-oxide (NMO) oxidizes coordinated PEt3 from LCo(PEt3)(2), but the final cobalt product is still divalent cobalt, in LCo(NMO)(2). The thermodynamics of a variety of oxygen atom transfer reagents, including NMO, are calculated by density functional theory, to rank their oxidizing power. Oxidation of LCo(PEt3)(2) with AgOTf in the presence of LiCl as a trapping nucleophile forms the unusual aggregate [LCo(PEt3)(2)Cl(LiOTf)(2)](2) held together by Li+ binding to very nucleophilic chloride on Co(III) and triflate binding to those Li+. In contrast, Cp2Fe+ effects oxidation to trivalent cobalt, to form (HL)Co(PEt3)(2)Cl+; proton and the chloride originate from solvent in a rare example of CH2Cl2 dehydrochlorination. An unexpected noncomplementary redox reaction is reported involving attack by 2e reductant PEt3 nucleophile on carbon of the le oxidant radical Cp2Fe+, forming a P-C bond and H+; this reaction competes in the reaction of LCo(PEt3)(2) with Cp2Fe+.