Cyclopropyldiphenylsulfonium tetrafluoroborate33462-81-630 % similar 2,4,6-Triphenylpyrylium tetrafluoroborate448-61-330 % similar Di-tert-butylphenylphosphonium tetrafluoroborate612088-55-830 % similar Tetramethylammonium tetrafluoroborate661-36-930 % similar