Examining the change from π-π stacked to hydrogen-bonded interactions in 1-alkyl-3-methylimidazolium bis(oxalate)borate ionic liquids

We propose to study the liquid structure of two ionic liquids with bis(oxalate)borate anions, [C1mim][BOB] and [C4mim][BOB], utilising H/D-isotopic substitution within the imidazolium cations combined with anions containing 11B to eliminate high sample absorption due to neutron capture by 10B and generate optimal quality data from the experiments for analysis. The objective of these studies is to verify that co-planar π-type association can be observed in [C1mim][BOB] and that this decreases, being replaced by increasing hydrogen-bonding, on lengthening the alkyl-substituent of the cation ([C4mim][BOB]). These results will test the AIMD simulations of the system and either support or disprove the original proposition from Angell and co-workers that directional (HB) and van der Waals rather than Coulomb interactions determine the characteristics of orthoborate ionic liquids.