| [P4444][Im] | Tetrabutylphosphonium imidazole |
| [P4444][CF3COO] | Tetrabutylphosphonium 2,2,2-trifluoroacetic acid |
| [P4444][Triz] | Tetrabutylphosphonium 1,2,4-triazole |
| [P4444][Ind] | Tetrabutylphosphonium indazole |
| [P4444][Br] | Tetrabutylphosphonium bromide |
| [P4444][NO3] | Tetrabutylphosphonium nitrate |