CRYSTAL-STRUCTURE OF THE ND, GD, AND DY SANDWICH COMPLEXES INVOLVING 8-MEMBERED MACROCYCLIC PHENYLSILOXANOLATE LIGANDS

An X-ray structural investigation of the interaction products of anhyd rous trivalent neodymium, gadolynium, and dysprosium chlorides with so dium phenylsiloxanolate was carried out. The synthesized compounds wit h the general formula Na6{[PhSiO2]8M4(mu4-O)[O2SiPh]8} . 10EtOH . 8H2O (M = Nd, Gd, Dy) were found to be isomorphous isostructural sandwich complexes. The macrocyclic octaphenyloctasiloxanolate ligands in the c omplexes have an all-cis-configuration and are arranged in co-axial an tiparallel pairs and coordinate the square planar groups of the four N d3+, Gd3+, or Dy3+ ions stabilized by an additional central mu4-bridgi ng O2- ligand. Six Na+ counterions form the outer coordination sphere of the complexes such that four of them coordinate the siloxane macroc ycle O atoms in pairs in analogy with crown-ether complexes.