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RESEARCH PRODUCT

MMX Chains and Molecular Species Containing Rh 2 n+ ( n = 4, 5, and 6) Units: Electrical Conductivity in Crystal Phase of MMX Polymers

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The control of the experimental conditions in the reaction of Rh 2 (O 2 CCH 3 ) 4 with halides allows the isolation of the novel dirhodium complexes K x [Rh 2 X(O 2 CCH 3 ) 4 ] x ·4xH 2 O (X = Br, 1·4H 2 O and I, 2·4H 2 O) [Rh 2 (O 2 CCH 3 ) 4 Cl] x H 2 O (3·H 2 O), [Rh 2 (O 2 CCH 3 )Cl] x ·4xH 2 O (3·4H 2 O), and {Rh 2 (O 2 CCH 3 ) 4 I 2 ]· 4H 2 0 (4·4H 2 O) containing Rh 2 n+ (n = 4, 5 and 6) units. The X-ray structure determination of compounds 1-4 reveals the presence of dirhodium units in different oxidation states. The polyanionic complexes 1·4H 2 O and 2·4H 2 O containing Rh 2 4+ units give zig-zag chains. In contrast, the partially oxidized complexes 3·H 2 O and 3·4H 2 O containing Rh 2 5+ units are linked by chloride ligands forming linear chains. The first tetracarboxylatodirhodium(III) compound 4·4H 2 O is also described. Its structure consists of discrete binuclear [Rh 2 (O 2 CCH 3 ) 4 ] 2+ units with both axial positions occupied by iodide ligands. The very simple synthetic procedures presented here to achieve the partial or complete oxidation of the dirhodium(II) precursors open new perspectives in dirhodium complexes containing different oxidation states and in their potential applications in the construction of molecular devices. The electrical characterization of the polymer chains confirms conductivity in crystal phase. In addition, isolation of 1·4H 2 O and 2·4H 2 O on mica and morphological characterization of individual chains by atomic-force microscopy have been achieved.