title: Three phenanthroline-metal complexes with topologically similar but geometrically different conformations.
abstract: The structures of three related complexes of general formulaM(pds)(nab)2[pdsis the peroxodi-sulfate anion andnabis an nitro-gen-containing aromatic base],viz. bis(2,9-dimethyl-1,10-phenanthroline-κ2N,N')(peroxodi-sulfato-κ2O,O')cadmium, [Cd(S2O8)(C14H12N2)2], (V), bis-(3,4,7,8-tetra-methy-1,10-phenanthroline-κ2N,N')(peroxodi-sulfato-κ2O,O')zinc, [Zn(S2O8)(C16H16N2)2], (VI), and bis-(3,4,7,8-tetra-methy-1,10-phenanthroline-κ2N,N')(peroxodi-sulfato-κ2O,O')cadmium, [Cd(S2O8)(C16H16N2)2], (VII), present the same topological coordination, with three chelating ligands in anMN4O2polyhedron. The main difference resides in the fact that the first two complexes are bis-ected by a crystallographic twofold axis, thus providing a symmetrical environment to the cation, while in the third one this symmetry is disrupted into a clearly unsymmetrical disposition, probably by way of an unusually strong intra-molecular C-H⋯O hydrogen bond. The situation is compared with similar inter-actions in the literature. The structure of (V) is based on a redetermination in the correct space groupC2/cof the structure originally described in theCcspace group [Harveyet al.(2001).Aust. J. Chem.54, 307-311; Marsh (2004 ▸).Acta Cryst.B60, 252-253].
authors.affiliation: Universidad Nacional de la Patagonia S.J.B., Sede Trelew, 9100 Trelew, Chubut, Argentina; CenPat, CONICET, 9120 Puerto Madryn, Chubut, Argentina.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Harvey
authors.affiliation: Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Suarez
authors.affiliation: Departamento de Física, Comisión Nacional de Energía Atómica, Buenos Aires, Argentina.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Baggio
keywords: Cd and Zn complexes; crystal structure; peroxodi­sulfate anion; strong C—H⋯O intra­molecular hydrogen bonds