Copper(i) and silver(i) coordination frameworks involving extended bipyridazine bridges

Abstract

1,4-(Pyridazin-4-yl)benzene (bpph), a new N-donor tetradentate ligand, was prepared by inverse electron demand cycloaddition reacting 1,4-diethynylbenzene and 1,2,4,5-tetrazine. In combination with Cu(I) and Ag(I) ions, it affords coordination framework topologies that were dominated by assembly of dinuclear metal–pyridazine “secondary building blocks” [M₂(μ-pdz)₂] supporting further polymeric connectivity. In structures [Cu₂(bpph)(CH₃CN)₂{S₂O₆}] (1) and [Ag₆(bpph)₃(H₂O)₆{C₆H₄(COO)₂}₂]C₆H₄(COO)₂·4H₂O (8) interconnection of the dinuclear nodes occurs with anionic dithionate and isophthalate bridges, while [Ag₂(bpph){C₆H₅CO₂}₂]·2H₂O (7) adopts a linear chain structure incorporating disilver(I) pyridazine units and terminal benzoate anions. [Cu₄(bpph)₅](BF₄)₄·4CHCl₃ (2) has a 3D supramolecular structure involving polycatenation of the 2D “bilayer” metal–organic topologies built up of five-connected dinuclear nodes. Frameworks of [Ag(bpph){NO₃}]·CHCl₃ (3) and [Ag(bpph){C₂F₅COO}] (5) exist as 2D square-grids nets supported with sets of tetra- and bidentate bipyridazine bridges, while closely related [Ag₄(bpph)₃{CF₃COO}₄]·CH₃CN (4) is a 1D “ladder” polymer. The three-fold interpenetrated 3D diamondoid framework of [Ag₄(bpph)₃{CH₃SO₃}₄]·2CHCl₃ (6) was based upon more complicated tetranuclear nodes [Ag₄(μ-pdz)₄(pdz)₂].