3H-2-benzopyran-3-one, 1,4-dihydro-7-nitro- 7-nitro-1,4-dihydro-3H-isochromen-3-one InChI=1/C9H7NO4/c11-9-4-6-1-2-8(10(12)13)3-7(6)5-14-9/h1-3H,4-5H