A new class of geminal dicationic ionic liquids was formed with a bridging moiety, such as a polyalkyl ether, polyfluoroalkyl, 1,4-bismethylenebenzene, or 1,4-bismethylene-2,3,5,6-tetrafluorobenzene link, between alkyl-substituted imidazolium rings. Their properties were modified by varying the linker chains and/or alkyl substituents on the imidazolium ring. The polyfluoroalkyl bridged dicationic ionic liquids exhibit the highest densities and viscosities. Although melting points are directly proportional to the length of the alkyl substituent, the densities decrease concomitantly. With 1,4-bismethylene-2,3,5,6tetrafluorobenzene as the linking chain and with longer alkyl substituents on the imidazolium rings, the nonpolar character of the ionic liquid greatly increases, e.g., the solubilities in toluene of dicationic ionic liquids 36 and 37, where the ring substituents are C 10 H 21 and C 14 H 29 , increase markedly. Some of the salts exhibit higher conductivities than an equimolar tetrabutylammonium iodide solution in acetonitrile/ toluene. These new ionic liquids (except with PF 6 as anion) display outstanding tribological properties in temperature ramp tests by performing very well at 300 °C, thus meeting one criterion for high-temperature lubricants.

At this stage, I've edited the manuscript for brevity and clarity. Queries are meant to draw your attention to edits, inconsistencies or issues that are unclear. If we just ask you to confirm edits are correct, a simple yes/ok between the brackets will do [Au:OK? Is this what you meant? Edits OK? yes]. If questions are asked, please rephrase/update the manuscript text when addressing queries, so that the message is conveyed to the reader (please do not just type your answer to our query unless it is unclear).As the reviewers noted, the manuscript is in very good shape and most comments and edits are fairly minor. However, there is an outstanding issue that must be addressed before we go forward. Figures 7 and 8 are currently referred to in the text in an alternating fashion (e.g. Figure 7A, 8A, 7B, 8B). This is against our style and might make that part of the manuscript difficult to follow for the reader owing to the need to refer to multiple figures at a time while reading the text. To clarify this issue, I recommend restructuring these figures. To do this, can you provide new chemdraw/PDFs with amended figures, including the following amendments: a. Merge Figures 7A and 8A to create a new 'Figure 7' that shows the methods of introducing CF2H at sp3-carbons. b. Merge figures 7B and 8B to make a new figure 8 that shows the main protocols of introducing CF2H at heteroaromatic carbons. 7C could be shown in it's own small figure (Figure 9) or could be added as panel B in the new figure 8. c. Amend the figure legends accordingly Apologies for another figure change but this is essential to keep the figure callouts in style and I think it will make the figures much easier for the reader to follow. I've asked the art editor to delay redrawing these particular figures until we receive these updated chemdraws/PDFs. If there are any issues with this change, please do let me know as soon as possible and we can discuss further.

Neat reactions of 2,2'-biimidazole with an excess of alkyl or polyfluoroalkyl iodides at 140 degrees C, followed by anion exchange with LiN(SO(2)CF(3))(2) or KPF(6), gave the diquaternary salts 3a-k in >80% yields. However, by controlling the reaction stoichiometry, 2,2'-biimidazole can also be monoquaternized with the same electrophiles at 100 degrees C under similar conditions. Subsequent metathesis reactions with LiN(SO(2)CF(3))(2) or KPF(6) resulted in the ionic liquids 4a-m in high yields. Thermal properties were determined with a differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA). Most of the monoquaternary salts are room-temperature ionic liquids. 1,3,1'-Tributyl-2,2'-biimidazolium hexafluorophosphate was demonstrated to be an excellent solvent and ligand for palladium-catalyzed Suzuki cross-coupling reactions. The catalytic ionic liquid system may be recycled at least 14 times without a significant decrease in catalytic performance.