Crystal structures of tris(nitrate)tris(N,N-dimethylacetamide)Er(III) and tris(nitrate)tris(N,N-dimethylacetamide)Sm(III)

The crystal structures of two compounds, with formula (C4H9NO)3(NO3)2Me, where Me = Er(III) or Sm(III), have been solved by X-ray diffraction methods. The crystals are: Er-complex, orthorhombic, Pbca, a =16.898(8), b = 17.095(9), c = 32.442(14) Å, V=9372(8) Å3, Z = 16, Dc = 1.74 mg · cm−3. Sm-complex, monoclinic, P21/n, a= 15.096(11), b = 14.578(10), c=10.700(8) Å, β = 94.04(7)°, V=2349 Å3, Z=4, Dc = 1.69 mg · cm−3. The structure of the first compound was solved using the DIRDIF system of computer programs, and the second with MULTAN system. The two structures were refined by least-squares to R-factors equal to 0.059 and 0.058, respectively, for all observed reflections. The two structures consist of discrete molecules linked by Van der Waals interaction. The coordination polyhedra are distorted tricapped trigonal prism. The N,N-dimethylacetamide ligands are attached in monodentate fashion and the nitrate ions in bidentate. The structural situation of the nitrate ions in Er-complex is different in the two crystallographic non-equivalent molecules, one showing a conformation similar to that of the Sm-complex. © 1983, Walter de Gruyter. All rights reserved.