Selectfluor140681-55-6100 % similar 1-Fluoro-4-methyl-1,4-diazabicyclo(2.2.2)octane-1,4-diium ditetrafluoroborate159269-48-450 % similar Tetrabutylammonium tetrafluoroborate429-42-537 % similar Tetraethylammonium tetrafluoroborate429-06-132 % similar