A method of synthesizing an ionic metal complex corresponding to formula (1) ##STR00001## in which a compound of formula (2) ##STR00002## and/or a compound of formula (3) E.sup.3-O--R.sup.2 (3) is reacted with a halogen containing compound in an organic solvent in the presence of a compound containing an element of group 1, group 2, group 13 or group 14 of the periodic table as a reaction aid.