The nitration of 1,1-diamino-2,2-dinitroethylenes, obtained by the reaction of amines with 1,1-diiododi-nitroethylene, was studied. Reaction of 2-(dinitromethylene) -1,3-diazacyclopentane (la) with nitric acid and trifluoroacetic anhydride in methylene chloride gave 3-nitro-2-(trinit romethy)-1,3-diazacyclopent-1-ene (3a) in high yield. Analogous products 3b-3d were obtained from 2-(dinitromethylene) -1,3-diazacyclohexane (1b), 2-(dinitromethylene) -1,3-diazacycloheptane (1c), and 3,9-bis(dinitromethylene) -2,4,8,10-tetraazaspiro undecane (1d). Nitration of 1a with nitric acid in sulfuric acid gave the correspondingnitrosamine 2a. Reductive denitrations of the trinitromethyl compounds 3a, 3b, and 3c with Potassium iodide gave salts of the corresponding dinitromethyl compounds 4a, 4b, and 4c. Bromination and chlorination of 4a afforded 2-(bromodinitromethyl) -3-nitro-1,3diazac yclopentent-1-ene (5) and 2-(chlorodinitrometbyl) -3-nitro-1,3-diazacyclopent-1-ene (6), respectively. Acidification of the salts 4a, 4b, and 4c gave 2-(dinitrometbylene) -l-nitro-1,3-diazacyclopentane (7a), 2-(dinitromethylene) -l-nitro-1,3-diazacyclohexane (7b), and 2-(dinitromethylene) -1-nitro-1,3-diazacycloheptane (7c), respectively. The nitration of 7a gave 3a. Nitrations of the diamino mononitro olefins, 2-(nitromethylene) 1,3-diazacyclopentane (8a) and 2-(nitromethylene) -1,3-diazacyclohexane (8b), gave 3a and 3b. The structures of 3a, 3d, 7a, 7b, and 7c were obtained by X-ray Crystallography. Olefin twist angles for 7a-7c, as high as 74.5 deg, arerationalized on the bases of ring geometry and hydrogen bonding. 1,1-Diamino-2,2-dinitroethylenes, nitration, NMR, twisted olefins, x-raycrystallography, trinitromethyl compounds.