title: Two new cobalt(II) fumarates and a redetermination of tetraaquacobalt(II) fumarate monohydrate.
abstract: Poly[triaqua-mu(4)-fumarato-cobalt(II)], [Co(C(4)H(2)O(4))(H(2)O)(3)](n), (I), contains two symmetry-independent octahedrally coordinated Co(2+) ions, both on inversion centers. One Co(2+) ion is coordinated by two water molecules and four fumarate dianions, whereas the other Co(2+) ion is surrounded by four water molecules and two fumarate dianions. Each fumarate dianion is bonded to three Co(2+) ions, leading to a two-dimensional structure. The fumarate dianions are nonplanar; the angle between the planes of the two carboxylate groups is 54.9 (2) degrees. The cobalt(II) fumarate layers are connected by hydrogen bonding into a three-dimensional network. Compound (I) is not isostructural with calcium(II) fumarate trihydrate [Gupta et al. (1972). Acta Cryst. B28, 135-139]. In poly[mu(4)-fumarato-dimethanolcobalt(II)], [Co(C(4)H(2)O(4))(CH(4)O)(2)](n), (II), the Co(2+) ions are octahedrally coordinated by four fumarate dianions and two methanol molecules, leading to a three-dimensional structure. The fumarate group is planar. The Co(2+) ions and the fumarate dianions both lie on inversion centers. Additionally, the one-dimensional structure of catena-poly[[[tetraaquacobalt(II)]-mu(2)-fumarato] monohydrate], {[Co(C(4)H(2)O(4))(H(2)O)(4)].H(2)O}(n), (III), was redetermined at a higher resolution, and the space group C2/c was confirmed.
authors.affiliation: Institute of Inorganic and Analytical Chemistry, Goethe University, D-60438 Frankfurt am Main, Germany.
authors.forename: Sándor L
authors.initials: SL
authors.lastname: Bekö
authors.forename: Jan W
authors.initials: JW
authors.lastname: Bats
authors.forename: Martin U
authors.initials: MU
authors.lastname: Schmidt
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005650:Fumarates / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*
chemical_list: D005650:Fumarates; D009942:Organometallic Compounds; C544575:poly(triaqua-mu(4)-fumarato-cobalt(II)); D003035:Cobalt