Type 6 complexes form when s-LUMO Lewis acids interact with Complex Anion Lewis bases to form the classic charge controlled (ionic) species such as lithium tetrafluoroborate, Li[BF4]. Type 6 complexes tend to be highly soluble in polar solvents in which the anion and cation are independently solvated: solvated Type 6 complexes show little or no ion-pairing. For more information look in the Chemogenesis
webbook sections on Lewis
acids and Lewis bases and the Lewis
acid/base interaction matrix.