title: Knotted network consisting of 3-threads and a zwitterionic one-dimensional polymorphs of trans-3-(3-pyridyl)acrylate of cobalt and nickel, MII(C8H6NO2)2(H2O)2.
abstract: We present the hydrothermal synthesis, characterization (IR, DT-TGA), single-crystal structures, and magnetic properties of two polymorphs of trans-3(3-pyridyl)acrylate of cobalt(II) and of nickel(II), M(II)(C(8)H(6)NO(2))(2)(H(2)O)(2). Hydrothermal reaction at 120 or 170 degrees C results exclusively in the different polymorphs. The infrared spectra and thermogravimetric analyses of the complexes are almost similar for the two polymorphs but show a difference between cobalt and nickel in energies of the vibrational modes and in the decomposition temperatures. The crystal structures of the two polymorphs are quite different; one crystallizes in a monoclinic space group and the other in a triclinic. This major difference is due to the different stereochemistry, cis or trans, of the coordination at the metal sites. When it is trans-MN(2)O(4), it results in the monoclinic cell consisting of a 3D-network of metals bridged by the ligands through single bonds (M-N and M-O). There is threading of three sublattices up to 2a x 4b x 2c, at which point the three sublattices are knotted into one infinite framework. When it is cis-MN(2)O(4), it results in the triclinic cell and consists of Zwitterionic linear chains of metals bridged by one single ligand via the pyridine and a bidentate carboxylate group and the other ligand is bonded only via the pyridine while its carboxylate end is free. All four compounds are paramagnetic with Weiss constants suggesting weak interactions.
authors.affiliation: Laboratoire de Chimie de Coordination Organique, CNRS-UMR7140, Université Louis Pasteur, 4 rue Blaise Pascal, F-67000 Strasbourg Cedex, France. kurmoo@chimie.u-strasbg.fr
authors.forename: Mohamedally
authors.initials: M
authors.lastname: Kurmoo
authors.forename: Claude
authors.initials: C
authors.lastname: Estournès
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Oka
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kumagai
authors.forename: Katsuya
authors.initials: K
authors.lastname: Inoue