SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF PRASEODYMIUM(III) AND NEODYMIUM(III) COMPLEXES OF TRIPODAL TRIS[2-(SALICYLIDENEAMINO)ETHYL]AMINE

The preparation and characterization of praseodymium(III) and neodymiu m(III) complexes of heptadentate (N4O3) ligand trensal, tris [2-(salic ylideneamino)ethyl] amine (H(3)L(1)), have been studied. These complex es (PrL(1) and NdL(1)) were prepared by the reaction of the praseodymi um(III) or neodymium(III) complex of 1,9-bis(2-aminoethyl)-1,4,6, 9,12 ,14-hexaazacyclohexadecane with salicylaldehyde in acetonitrile. Alter natively, the reaction of tris(2-aminoethyl)amine and salicylaldehyde in the presence of praseodymium(III) or neodymium(III) salt in acetoni trile also gave praseodymium(III) and neodymium(III) complexes of tren sal. The molecular structures of PrL(1) and NdL(1) were determined by X-ray structural analysis; these are rare examples of lanthanide hepta dentate complexes in which the metal ions are coordinated by the four nitrogen atoms and the three oxygen atoms. The crystals of PT(C27H27N4 O3). 0.5CH(3)CN and Nd(C27H27N4O3). 0.5CH(3)CN are both trigonal, spac e group P (3) over bar, a=13.713(2), c=8.093(3) Angstrom, U=1318.0(7) Angstrom(3), Z=2 for [PrL(1)]. 0.5CH(3)CN, and a=13.724(3), c=8.067(3) Angstrom, U=1315.8(7) Angstrom(3), Z=2 for [NdL(1)]. 0.5CH(3)CN. The structures were solved by heavy-atom Patterson methods and expanded us ing Fourier techniques; they were then refined by full-matrix least-sq uares procedures to R=0.033 and R(w)=0.043 for 1547 observed reflectio ns with I greater than or equal to 3 sigma(I), R=0.028 and R(w)=0.039 for 1923 observed reflections with I greater than or equal to 3 sigma( I) for [PrL(1)]. 0.5CH(3)CN and [NdL(1)]. 0.5CH(3)CN, respectively. Th e individual metal ions and the apical nitrogen atoms lie on a 3-fold axis in each crystal; the molecules possess a C-3 molecular symmetry.