Selenium- and tellurium-containing bis(diphenylphosphinoyl)methane monoanions were prepared by oxidation of the anion [HC(PPh2)(2)](-) with elemental chalcogens. The selenium-containing isopropyl derivative was synthesized by generating [H2C((PPr2)-Pr-i)(2)] via a reaction between [H2C(PCl2)(2)] and 4 equiv of (PrMgCl)-Pr-i prior to in situ oxidation with selenium followed by deprotonation with (LiNPr2)-Pr-i. The solid-state structures of the lithium salts of the monochalcogeno anions TMEDA center dot Li[HC(PPh2E)(PPh2)] (E = Se (Li7a), E = Te (Li7b)) and the dichalcogeno anions TMEDA center dot Li[HC-(PR2Se)(2)] (R=Ph (Li8a), Pr-i (Li8c)) revealed five- and six-membered LiEPCP and LiSePCPSe rings, respectively. The homoleptic group 12 complexes {M[HC(PPh2Se)(2)](2)} (M=Zn (9a), Hg (9b)) were prepared from Li8a and MCl2 and shown to have distorted-tetrahedral structures; the nonplanarity of the carbon center in the PC(H)P unit of the Zn complex 9a is attributed to crystal-packing effects. The complexes Li7a, Li7b, Li8a, TMEDA center dot Li[HC(PPh2Te)(2)] (Li8b), Li8c, 9a, and 9b were characterized in solution by multinuclear (H-1, Li-7, C-13, P-31, Se-77, Te-125, and Hg-199) NMR spectroscopy. One-electron oxidation of Li8a and Li8c with iodine in a variety of organic solvents produced [H2C(PR2Se)(2)] (R=Pr-i, Ph) as the final product, presumably owing to hydrogen abstraction from the solvent. DFT calculations revealed a significant contribution from the p orbital on carbon to the SOMO of the radicals [HC(PR2Se)(2)](center dot) (R=Pr-i, Ph).