1,3-Dimethyl-2-fluoroimidazolium hexafluorophosphate164298-27-5100 % similar Tetramethylfluoroformamidinium hexafluorophosphate164298-23-156 % similar 1,3-Dimethyl-2-imidazolidinethione13461-16-033 % similar 1,3-Dimethyl-2-imidazolidinone80-73-933 % similar 2-Chloro-1,3-dimethylimidazolidium tetrafluoroborate153433-26-231 % similar