New lipide soluble complexes of cations like metal ions and ammonium ions are prepared by reacting an uncharged complex forming substance with the corresponding ions. Preferred uncharged complex forming substances are also new. The new lipide soluble complexes of cations have a wide field of application and those complexes, that is, the complex forming compounds can be used in membranes for the determination of the concentration of cations, like the ion sensitive members of measuring electrodes, or for the performance of an electro dialysis. Metal cations are generally insoluble in organic solvents and due to their solubility in organic solvents the new lipide soluble complexes of cations can be used in many fields of application, e.g. as catalysts for reactions which are performed in organic solvents.