Patent ID: 8801811

Claim:
A method of using a nanoparticle Fe 0 6 -crown ether complex as an additive, the complex being prepared by a method comprising the steps of: preparing dialkylamine or ethylenediamine solutions of iron (II) complexes with olygomer crown ethers, containing two nitrogen atoms in a macrocyclic ring at a temperature; adding a solution of sodium tetrahydroboron in ethylene diamine and mixing the result; heating the resulting mixture and then boiling the mixture; filtering the resulting mixture under a nitrogen atmosphere; adding ethanol to the resulting mixture to reduce excess NaBH 4 , and continuing to boil the mixture until at least half of the ethylene diamine has been removed; and cooling the mixture to below 5° C. to precipitate a nanoparticle Fe 0 6 -crown ether complex CWFe 6 .