title: Complexes of Ag(I), Hg(I) and Hg(II) with multidentate pyrazolyl-pyridine ligands: From mononuclear complexes to coordination polymers via helicates, a mesocate, a cage and a catenate.
abstract: The coordination chemistry of a series of di- and tri-nucleating ligands with Ag(I), Hg(I) and Hg(II) has been investigated. Most of the ligands contain two or three N,N'-bidentate chelating pyrazolyl-pyridine units pendant from a central aromatic spacer; one contains three binding sites (2 + 3 + 2-dentate) in a linear sequence. A series of thirteen complexes has been structurally characterised displaying a wide range of structural types. Bis-bidentate bridging ligands react with Ag(I) to give complexes in which Ag(I) is four-coordinate from two bidentate donors, but the complexes can take the form of one-dimensional coordination polymers, or dinuclear complexes (mesocate or helicate). A tris-bidentate triangular ligand forms a complicated two-dimensional coordination network with Ag(I) in which Ag...Ag contacts, as well as metal-ligand coordination bonds, play a significant role. Three dinuclear Hg(I) complexes were isolated which contain an {Hg2}2+ metal-metal bonded core bound to a single bis-bidentate ligand which can span both metal ions. Also characterised were a series of Hg(II) complexes comprising a simple mononuclear four-coordinate Hg(II) complex, a tetrahedral Hg(II)4 cage which incorporates a counter-ion in its central cavity, a trinuclear double helicate, and a trinuclear catenated structure in which two long ligands have spontaneously formed interlocked metallomacrocyclic rings thanks to cyclometallation of two of the Hg(II) centres.
authors.affiliation: Department of Chemistry, University of Sheffield, Sheffield, UK S3 7HF.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Argent
authors.forename: Harry
authors.initials: H
authors.lastname: Adams
authors.forename: Thomas
authors.initials: T
authors.lastname: Riis-Johannessen
authors.forename: John C
authors.initials: JC
authors.lastname: Jeffery
authors.forename: Lindsay P
authors.initials: LP
authors.lastname: Harding
authors.forename: William
authors.initials: W
authors.lastname: Clegg
authors.forename: Ross W
authors.initials: RW
authors.lastname: Harrington
authors.forename: Michael D
authors.initials: MD
authors.lastname: Ward