Effects of closo-icosahedral periodoborane salts on hypergolic reactions of 70% H2O2 with energetic ionic liquidsElectronic supplementary information (ESI) available. CCDC 1590191 and 1590192. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8ta03780a

A number of energetic ionic liquids (EILs) have been reported as promising hydrazine-replacement fuels for hypergolic rocket propulsion. However, most of these EILs were ignited using corrosive and hazardous concentrated fuming nitric acid. Very significant efforts were recently made to utilize "rocket grade" highly concentrated H 2 O 2 (>90%) as a "green" alternative to fuming nitric acid and N 2 O 4 oxidizers. Although "rocket grade" H 2 O 2 is more challenging to use and less safe for storage than commercially available H 2 O 2 (70%), the latter is not considered as a viable oxidizer for hypergolic propulsion. In this work, we focused on the development of novel iodine-rich promoters, capable of initiating hypergolic ignition reactions between a typical EIL fuel - 3-ethyl-1-methyl-1 H -imidazol-3-ium cyanotrihydroborate - and H 2 O 2 . Among the prepared and evaluated promoters, the top performing [FcCH 2 NEtMe 2 + ] 2 [B 12 I 12 2− ] compound 5 showed ignition delay times of 45 ms in the reaction of the tested EIL with H 2 O 2 (70%) and 17 ms with H 2 O 2 (95%). We believe that these findings provide a platform for the development and utilization of commercially available H 2 O 2 as a potential "green" oxidizer for rocket propulsion. A number of energetic ionic liquids (EILs) have been reported as promising hydrazine-replacement fuels for hypergolic rocket propulsion.