CRYSTALLOGRAPHIC STUDES OF DIMETHYL SULFOXIDE COMPLEXES OF RARE EARTH (III) NITRATES. Lioubov I. Semenova, Brian W. Skelton and Allan H. White Department of Chemistry, University of Western Australia, Nedlands, W.A. 6907

Adducts [(dmso)_nLn(O₂NO)₃] have been the subject of a series of room temperature single crystal X-ray studies, defining more clearly the manner in which stoichiometry and structure systematically vary with change in metal ion radius. All complexes studied are mononuclear, the metal ion being complexed by three bidentate nitrate ligands and a number of dmso ligands: n = 4 for the light rare earths and n = 3 for the heavier. The array La - Sm is monoclinic C2/c, a ~ 14.9, b ~ 15.5 c ~ 15.5 Å, [[beta]] ~ 108.4deg., Z = 4 f.u.; the metal atom is disposed on a crystallographic 2 -axis, which also passes through one of the nitrate groups (I). The series Eu - Tm (inclusive also of Y) is monoclinic, P2₁/n, a ~ 11.5, b ~ 12.7, c ~ 13.6 Å, [[beta]] ~ 100deg.,

Z = 4 f.u., while Yb, Lu are also monoclinic, P2₁/c, a ~ 10.0, b ~ 12.6, c ~ 16 Å,

[[beta]] ~ 100.6deg., z = 4 f.u.(II).