Crystal and molecular structure of 3-chloro-3,6-dinitro-2,2-dimethyl-4-chromanone, C11H9N2O6Cl

3-Chloro-3,6-dinitro-2,2-dimethyl-4-chromanone is the first 3-chloro-3-nitr o-4-chromanone to be synthesized by nitrating its corresponding 4-chromanon e at the 3 position and then chlorinating the nitration product. Its struct ure was determined by IR, NMR, MS and x-ray crystallography. It crystallize s as a pair of enantiomers with 2 molecules in the primitive triclinic spac e group P (1) over bar(#2) with a = 9.476(2), b = 10.906(3), c = 6.578(5) A ngstrom, and alpha = 101.08(3), beta = 90.13(3), gamma = 73.23(1)degrees, V = 637.7500 Angstrom(3), and Z = 2. The nitro group at the 6 position conju gates with the benzene ring. The pyranone ring has a half-chair conformatio n; the chloro group occupies the pseudoequatorial position, and the nitro g roup occupies the pseudoaxial position. The 2 and 3 positions are essential ly antiperiplanar, minimizing steric interaction.