TETRASELENA CROWN-ETHERS - SYNTHESIS AND COMPLEXATION WITH MERCURY SALTS - CRYSTAL-STRUCTURE OF A MACROCYCLE AND A MERCURY(II) COMPLEX

Dipotassium benzene-1,2-diselenolate, C6H4(SeK)(2)-1,2 obtained from t he reaction of potassium tert-butoxide with a (benzene-1,2-diselenolat o)zirconocene, was treated with C6H4[SeCH2(CH2OCH2)(n)CH(2)X](2)-1,2 ( X = Cl, n = 11, n = 22, n = 33 or X = Pr n = 34) leading to tetraselen acrown ethers C6H4[SeCH2(CH2OCH2)(n)CH2Se](2)- C6H4 (n = 16, n = 27 or n = 38) in a moderate yield (10-20%). This yield can be increased by using the 'caesium effect' from benzene-1,2-diselenol (18-40%). These macrocyclic compounds are able to complex heavy metals [especially mer cury(II) ions] via their selenium atoms. The mercury complexes have be en characterized by multinuclear NMR spectroscopy. The molecular struc tures of the tetraselenacrown ether 7 and the mercury complex of macro cycle 8 have been established by X-ray diffraction.