STRUCTURES OF THREE NOVEL DINUCLEAR COMPLEXES OF Eu(III), Pr(III) and Nd(III) WITH BRIDGING ALANINEHYDROXAMIC ACID. By Zdzislaw Galdecki, Institute of General and Ecological Chemistry, Technical University of Lódz, ul. Zwirki 36, 90-924 Lódz, Poland

The structures of bis(u-D,L-[[alpha]]-alaninehydroxamic acid-1:2[[kappa]]²O,1[[kappa]]O') bis(hexaaquaeuropium)(6+) tetraoxochlorate(1-), [Eu(D,L-[[alpha]]Alaha)(H₂O)₆]₂(ClO₄₆ (1), and the isostructural complexes of neodymium (2), and praseodymium (3) have been determined. The compounds were synthesized by J. Legendziewicz and P. Gawryszewska at the Institute of Chemistry of the Wroclaw University and this study is a part of a broader investigation of novel complexes of lanthanides as model substances in biological systems.

The investigated complexes are binuclear, the lanthanide atoms coordinate 9 oxygen atoms: 6 water molecules, one oxygen atom of carboxyl group and two bridging oxygen atoms of hydroxamic groups. Unexpectedly the bridging oxygen atom in the complexes is not the carboxyl-oxygen atom, but the hydroxamic-oxygen atom. X-ray data were collected on a KM-4 diffractometer with Mo K[[alpha]] radiation at 293 K. The structures were solved by direct methods and refined by full-matrix least squares using SHELXTL-PC programs, on F values, with anisotropic temperature factors for non-hydrogen atoms. Positions of hydrogen atoms were taken from [[Delta]]F syntheses and refined with isotropic temperature factors. The space grup of the isostructural complexes is P2₁/n (Z=4) and the crystal data and R factors are given below:

Compound    a[Å]       b[Å]       c[Å]       b[o]       Final R  
1           10.345(2)  11.312(2)  16.957(3)  95.39(3)   0.041    
2           10.317(3)  11.332(4)  16.876(4)  95.90(3)   0.046    
3           10.464(2)  11.329(1)  16.963(3)  95.90(3)   0.035