Reaction of PNPCo, where PNP is ((Bu2PCH2SiMe2)-Bu-t)(2)N-, with the persistent radical galvinoxyl, G, gives PNPCo(parallel to)G, a nonplanar S = 3/2 species. Reaction with PhCH2Cl or with 0.5 mol I-2 gives PNPCoX (X = Cl or I, respectively), but additional I-2, Seeking Co-parallel to|, gives instead oxidation at phosphorus: ((Bu2P)-Bu-t(I)(CH2SiMe2NSiMe2CH2PBu2)-Bu-t)CoI2. Hydrogen-atom transfer reagents fail to give PNPCoH, but H-2 gives instead PNPCo(H)2, a result rationalized thermodynamically based on DFT calculations. Multiple equiv of PhSiH3 give a product of Co(V), where N/SiPh and P/Si bonds have formed. N2CH(SiMe3) gives a 1:1 adduct of PNPCo, whose metric parameters suggest partial oxidation above Col; N2CHPh gives a 1:1 adduct but with very different spectroscopic features. PhN3 reacts fast, via several intermediates detected below 0 degrees C, to finally release N-2 and form a Col product where one phosphorus has been oxidized, PN(P = NPh)Co. Whereas PNPCo(N-3) resists loss of N-2 on heating, one electron oxidation gives a rapid loss of N-2, and the remaining nitride nitrogen is quickly incorporated into the chelate ligand, giving [(Bu2PCH2SiMe2NSiMe2NP)-Bu-t(Bu-t(2))=CH2Co]. O-2 or Phl = O generally gives products where one or both phosphorus centers are converted to its oxide, bonded to cobalt.