Monomer, dimer, tetramer and salt: Structural variations in Zn(II) complexes of 4,4′-bipyridine-N,N′-dioxide

Complexes of ZnII salts with 4,4′-bipyridine-N,N′-dioxide (bpdo) have been prepared by solvathermal and solvent layering methods. Three complexes were obtained from ZnBr2: 1 is a 2D coordination polymer [Zn2Br4(bpdo)2]n, (2) a discrete trimetallic molecule [Zn3Br6(H2O)2(bpdo)4] and 3 a salt [ZnBr4][Zn(H2O)5(bpdo)]. Complexes 2 and 3 contain ZnII ions in both octahedral and tetrahedral coordination geometry. While in 2, these are covalently linked by bridging bpdo ligands forming zwitterionic trimetallic molecules, in 3 there is complete charge separation into [ZnBr4]2− anions and [Zn(H2O)5(bpdo)]2+ cations. When Zn(NCS)2 is used as starting material, a 1D coordination polymer [Zn(H2O)2 (bpdo)(NCS)2]n is obtained.

Reaction of 4,4′-bipyridine-N,N′-dioxide with ZnBr2 under different crystallisation conditions allows formation of three different complexes. These, and a similar complex formed from Zn(NCS)2 have been characterised by crystallographic methods.Figure optionsDownload as PowerPoint slide