Synthesis and structure of new Zn(II) and Co(II) coordination polymers with 1,3,5-benzenetricarboxylic acid

Resumo

Two new Zn(II) and Co(II) compounds obtained by reactions of tetrafluoroborates of these metals with 1,3,5-benzenetricarboxylic (trimesic) acid (H₃Btc) and 1,3-bis(pyridyl)propane (Bpp) as an additional ligand were studied by X-ray diffraction. The formation of coordination polymers of various dimensionality, {[Zn₄(Bpp)₄(HBtc)₃((Me)Btc)]{(Me)₂HBtc} · 2H2O}_n (I), 1D, and {[Co₄(μ₃-OH)₂(Btc)₂(H₂O)₈] · 4(H₂O)}_n (II), 2D (CIF files CCDC no. 1552167 (I), 1552168 (II)) was demonstrated. Since H3Btc is partially methylated during the reaction, in I, this acid is stabilized in three forms: HBtc^2–, (Me)Btc^2–, and (Me)₂HBtc. The tetrahedral Zn(II) coordination polyhedron is formed by the N₂O₂ set of donor atoms: the O atoms belong to two different carboxylate ligands, HBtc^2– and (Me)Btc^2–, while the N atoms belong to two Bpp ligands. In II, the Bpp ligand is not incorporated in the complex and H₃Btc is coordinated to five metal atoms as a triply deprotonated ligand. Two carboxyl groups are coordinated to Co atoms as bidentate bridging ligands, while the third group is monodentate. The octahedral coordination polyhedra of Co(II) atoms in II are supplemented by terminal water molecules and μ₃-bridging OH^– groups.