| Abstract |
The bulk nanostructures of a prototypical good solvate ionic liquid (SIL) and poor SIL have been examined using neutron diffraction and empirical potential structure refinement (EPSR) simulated fits. The good SIL formed by a 1:1 mixture of lithium bis(trifluoromethylsulfonypimide (li[TFSI]) in tetraglyme (G4), denoted [Li(G4)][TFSI], and the poor SIl formed from a 1:1 mixture of lithium nitrate (li[NO3]) in G4, denoted [Li(G4)][NO3], have been studied. In both SIls there are strong lewis acid base interactions between Li+ and ligating 0 atoms. However, the 0 atoms coordinated to L+ depend strongly on the counter anion present. Li center dot center dot center dot O coordination numbers with G4 are 2-3 times higher for [Li(G(4))][TFSI] than [Li(G4)][NO3], and conversely the Li center dot center dot center dot O anion coordination number is 2-3 times higher in [Li(G(4))][NO3]. In both solvates the local packing of li around G4 0 atoms are identical but these interactions are less frequent in [Li(G4)][NO3]. In both SIls, Li+ has a distribution of coordination numbers and a wide variety of different complex structures are present. For [Li(G4)][NO3], there is a significant proportion uncoordinated G4 in the bulk; 37\% of gEyme molecules have no li .0 contacts and each G4 molecule coordinates to an average of 0.5 Li+ cations. Conversely, in [Li(G4)][TFSI] only similar to 5\% of G4 molecules lack Li center dot center dot center dot O contacts and G4 molecules coordinates to an average of 1.3 Li+ cations. Li+ and G4 form polynuclear complexes, of the form [Lix(G4)y]x+, in both solvates. For [Li(G4)][TFSI] 35\% of Li+ and G4 form 1 polynuclear complexes, while only 10\% of Li+ and G4 form polynuclear complexes in [Li(G4)][NO3]. |
