NOVEL POLYNUCLEAR ORGANOTIN COMPLEXES OF SAMARIUM AND YTTERBIUM

Polynuclear complexes [(Me3Sn)3Sn]2Ln(THF)4 (Ln = Sm (1), Yb (2)) have been synthesized by reacting Me3SnCl with samarium or ytterbium in THF. The crystals of 1 and 2 are orthorhombic (a = 21.511(2), b = 13.215(3), c = 20.640(4) angstrom, Z = 4, space group Pca2(1) for Ln = Sm and a = 21.534(3), b = 13.158(2), c = 20.616 angstrom, Z = 4 space group Pca2(1) for Ln = Yb). A similar organotin complex of ytterbium, [(Me3Sn)3Sn]2Yb(THF)4 (3) having the same composition but different structure than compound 2 has been isolated from the reaction of MeSnCl3 with Yb. The crystals of the compound 3 are tetragonal, a = 20.851(4), c = 26.311(5) angstrom, Z = 8, space group I42dBAR. In all cases the molecules of [(Me3Sn)3Sn]2Ln(THF)4 have a distorted octahedral structure in which the central Ln (Ln = Sm, Yb) atom is bonded to four oxygen atoms of THF molecules in equatorial positions and two tin atoms of (Me3Sn)3Sn groups in axial positions. The molecule of 3 has a C2 symmetry and an approximately eclipsed arrangement of (Me3Sn)3Sn groups. The Yb-Sn distance is 3.300(4) angstrom. The molecules of 1 and 2 have a staggered arrangement of the (MeSn)3Sn groups with Ln-Sn distances of 3.402(4), and 3.386(4) angstrom for Ln = Sm, and 3.289(5) and 3.299(4) angstrom for Ln = Yb.