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039ChemInform Abstract The sodium salt (IV) of the title heteropoly anion, prepared according to the scheme (no yield given), crystallizes in the monoclinic system, space group P21/n, Z=2. The anion is the first polytungstate ion to contain six paramagnetic centers and the first with four paramagnetic centers bridged by a single oxygen atom. Two octahedral Cu(II) sites, two octahedral Fe(III) sites, and two tetrahedral Fe(III) sites form a Cu2Fe4O21 core. The cationic portion of the structure consists of two (Na5O22)5+ oxygen-bridged structure draping the anion in necklace fashion. The magnetic susceptibility of the salt (IV), determined between 4 and 374 K, exhibits strong antiferromagnetic interaction at low temperature. The EPR spectrum in the 77-300 K range suggests that six central metal ions participatein the magnetism in this temp. range.

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EPR and magnetic susceptibility data (emphasis on the intramolecular spin‐exchange coupling process) are reported for the trimeric Cu(II) complex ((W9AsO33)2Cu3(H2O)2)12‐.