Poly(pyrazolyl)germanium(II) and -tin(II) Derivatives-Tuneable Monoanionic Ligands and Dinuclear Cationic Cages

Abstract

The barium complex Ba[(Pz*)3Ge]2 1/2dioxane 4, and the separated ion pairs [Ge2(Pz*)3][GeCl3] l/2dioxane 5 and [Sn2(Pz*)3][SnCl3], 6 (Pz* = 3,5-dimethyl pyrazol-l-yl), were obtained in the reaction of Ba(Pz*)2, 3, with GeCl2 dioxane and SnCl2, respectively, in THF. A molar ratio of 3:2 (3:GeCl2 dioxane) leads to the homoleptic complex 4. Two monoanionic [(Pz*)3Ge] ligands shield the central barium cation. X-ray structure determination proves two Pz* substituents of either germanate ligand donate to the central barium metal Ν(σ) (average Ba-Ν 280.3 pm) while the third is side-on coordinated. Both nitrogen atoms of either side-on ring coordinate to the barium center (average Ba-N 294.7 pm). If the molar ratio in the reaction is changed to 1:2 (3:GeCl2*dioxane, SnCl2 respectively), 5 and 6 are formed. The solid state structures are of salt like ionic composition, determined by X-ray structure analysis. The [E2(Pz*)3]+ cations consist of two E(II) atoms (E = Ge, Sn), which are symmetrically exo-bidentate bridged by three pyrazolyl substituents, while [ECl3]− is the counterion. In contrast to 5, there are weak intermolecular interactions in 6, involving two cations and two anions. In addition the unit cells of 4 and 5 contain an uncoordinated dioxane molecule as lattice solvent. © 1995, American Chemical Society. All rights reserved.