Stability of the compounds with the octahedral [MII(κ3-L)2] coordination building blocks of late 3d elements via solvate water supramolecular arrangement

Abstract

Five new coordination compounds with the common formulae [MII(bdmpza)2]•xH2O (bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate, C11H15N4COO-; x = 2 for Co (1), Ni (2) and Zn (3), x = 3 for Mn (4) and Fe (5)), were synthesized from the reaction mixtures containing appropriate metal salt, bis(3,5-dimethylpyrazol-1-yl)acetic acid (Hbdmpza), methanol and water. The X-ray single crystal diffraction analysis reveals that all five compounds (1-5) contain mononuclear homoleptic [MII(bdmpza)2] coordination molecules, in which the central metal ions are surrounded with two chelating bdmpza ligands. Each ligand is bound tridentately facially via κ3-N,N,O sites and centrosymmetric coordination chromophore is thus obtained. In the dihydrates [M(L)2]•2H2O, 1-3, every coordination molecule is linked by two water molecules, i.e. two pairs of O-H...O hydrogen bonds, on each of the two sides, thus forming infinite chain. In case of the trihydrates [M(L)2]•3H2O, 4-5, with an assistance of the additional water molecule, such chains are further connected into extended supramolecular sheets. A similarity of both hydrate types is confirmed by powder XRD data and IR analysis. The ionic metal radius and the coordination M-O, M-N bonds were related to the void dimension among the coordination molecules of the title [MII(bdmpza)2]•xH2O.

Keywords

• bdmpza
• 3d element
• hydrates
• hydrogen bonding
• supramolecular
• isostructural