Structure of 1-ethyl-3-methylimidazolium chloroaluminates: Neutron diffraction measurements and ab initio calculations

The structures of AlCl3-1-ethyl-3-methyl-imidazolium chloride melts in the concentration range of 46-67 mol% AlCl3 were measured by neutron diffractio n techniques. Ab initio molecular orbital calculations (6-31G* basis set) w ere carried out on the isolated ions which are known to form in these melts (AlCl4-, Al2Cl7-, and EMI+) and some of their complexes (AlCl4-... EMI+ an d Al2Cl7-... EMI+). The structures and binding energies of AlCl4-... EMI+ a nd Al2Cl7-... EMI+ are presented. The diffraction patterns derived from the complexes and the isolated ions are compared with the measurements.