Synthesis and structural study by wide-angle X-ray scattering (WAXS) of polymeric {Ln(2)[M(opba)](3)}center dot S compounds containing 4f Ln(III) and3d M-II {Ln(2)[M(opba)](3)}center dot S ions [opba = ortho-phenylenebis(oxamato), S = solvent molecules]

The compounds of formula Ln(2)[M(opba)](3). xH(2)O . yDMSO containing 4f Ln (III) and 3d M-II ions have been synthesized; opba stands for ortho-phenyle nebis(oxamato). These compounds crystallize poorly, and hence structural in formation has been obtained from the wide angle X-ray scattering (WAXS) tec hnique. It has been shown that the compounds present the same ladder-like m otif as that previously described for Tm,[Cu(opba)](3). 4H(2)O . 10DME Chan ging the Ln(III) and/or M-II ions results in more or less pronounced distor tions of the ladders. For a given M-II ion, changing the Ln(III) ion from L a-III to Lu-III results in a decrease of the Ln-M distance parallel to the lanthanide contraction. In the same way, for a given rare earth, changing t he M-II ion from Cu-II to Ni-II and Zn-II ions also results in the decrease of the Ln-M distance in accord with the decreasing radii of the M-II ions. The structural details have been analyzed and discussed.