POLY(PYRAZOLYL)GERMANIUM(II) AND POLY(PYRAZOLYL)TIN(II) DERIVATIVES - TUNABLE MONOANIONIC LIGANDS AND DINUCLEAR CATIONIC CAGES

The barium complex Ba[(Pz(*))(3)Ge](2) .(1)/(2)dioxane 4, and the separated ion pairs [Ge-2(Pz*)(3)][GeC1(3)].(1)/(2)dioxane 5 and [Sn-2(Pz*)(3)][SnCl3], 6 (Pz* = 3,5-dimethyl pyrazol-1-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*)(3)Ge] ligands shield the central barium cation. X-ray structure determination proves two Pz* substituents of either germanate ligand donate to the central barium metal N(sigma) (average Ba-N 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 [E(2)(Pz*)3](+) cations consist of two E(II) atoms (E = Ge, Sn), which are symmetrically exo-bidentate bridged by three pyrazolyl substituents, while [ECl(3)](-) 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.