2H-pyrimido[1,2-b]pyridazin-2-one, 7-chloro- 7-chloro-2H-pyrimido[1,2-b]pyridazin-2-one InChI=1/C7H4ClN3O/c8-5-1-2-6-9-7(12)3-4-11(6)10-5/h1-4