Molecular Architectures Derived from Metal Ions and the Flexible 3,3′-Bipyridine Ligand: Unexpected Dimer with Hg(II)

The flexible ditopic ligand 3,3′-bipyridine (3,3′-bpy) has been reacted with a series of transition metal species (Ag(+), Hg(2+), cis-a(2)M(2+) (a = NH(3) or a(2) = en; M = Pt, Pd), trans-a(2)Pt(2+) (a = NH(3))) in an attempt to produce discrete cyclic constructs. While Ag(+) gave a polymeric structure {[Ag(3,3′-bpy)](ClO(4)) · H(2)O}(n) (1), with all other metal entities cyclic structures were formed. Interestingly, Hg(CH(3)COO)(2) produced a dinuclear complex [Hg(3,3′-bpy)(CH(3)COO)(2)](2) · 3H(2)O (2), in which the two 3,3′-bpy ligands adopt a cis-orientation of the coordinating pyridyl entities. With cis-(NH(3))(2)Pt(2+), a cyclic complex 4 was isolated in crystalline form which, according to HRMS, is a trimer. With trans-(NH(3))(2)Pt(2+), different species are formed according to (1)H NMR spectroscopy, the nature of which was not established.