3-[2-[4-[4-Fluoro-2-[4-(6-fluoro-1,2-benzisoxazol-3-yl)piperidin-1-yl]benzolyl]piperidin-1-yl]ethyl-2-Methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyriMidin-4-one (Risperidone IMpurity) [ 1329796-66-8 ]