SYNTHESIS AND CHARACTERIZATION OF A NOVEL TETRANUCLEAR BIMETALLIC COMPLEX CONTAINING RHODIUM(II) AND ZINC(II) AS METAL CENTERS

Rh(Hdmg)(2)(PPh(3))Cl (Hdmg = monoanion of dimethylglyoxime) undergoes reduction with zinc amalgam to give the tetranuclear bimetallic compound [Rh(Hdmg)(ClZndmg) (PPh(3))](2), characterized by elemental analysis, electronic, IR and NMR spectroscopy and X-ray crystallography. It crystallizes in the triclinic space group P $($) over bar$$ 1 with: a = 14.262(4), b = 14.675(4), c = 14.698(4) Angstrom, alpha = 82.15(4), beta = 87.57(4), gamma = 65.89(3)degrees, Z = 2. The structure was refined up to R = 0.13 for 4704 reflections. The molecule consists of two [Rh(dmg) (Hdmg) (PPh(3))] subunits linked by an [Rh(II)-Rh(II)] bond of length equal to 2.852(3) Angstrom and by two Zn ions bridging the oxygens of the equatorial ligands. The binding with zinc relieves the equivalence among the atoms of each subunit.