The Group Ilia Lewis acids have the general formula R??MX n , wherein M is a Group Ilia metal, R is a monovalent hydrocarbon radical selected from the group consisting of Ci to C1 2 alkyl, aryl, alkylaryl, arylalkyl and cycloalkyl radicals; m is a number from 0 to 3; X is a halogen independently selected from the group consisting of fluorine, chlorine, bromine, and iodine; and the sum of m and n i