Syntheses, structural characterization and properties of transition metal complexes of 5,5′-(1,4-phenylene)bis(1H-tetrazole) (H2bdt), 5′,5′′-(1,1′-biphenyl)-4,4′-diylbis(1H-tetrazole) (H2dbdt) and 5,5′,5′′-(1,3,5-phenylene)tris(1H-tetrazole) (H3btt)

Abstract

The hydrothermal chemistry of a variety of M(II)SO₄ salts with the tetrazole (Ht) ligands 5,5′-(1,4-phenylene)bis(1H-tetrazole) (H₂bdt), 5′,5′′-(1,1′-biphenyl)4,4′-diylbis(1H-tetrazole) (H₂dbdt) and 5,5′,5′′-(1,3,5-phenylene)tris(1H-tetrazole) (H₃btt) was investigated. In the case of Co(II), three phases were isolated, two of which incorporated sulfate: [Co₅F₂(dbdt)₄(H₂O)₆]·2H₂O (1·2H₂O), [Co₄(OH)₂(SO₄)(bdt)₂(H₂O)₄] (2) and [Co₃(OH)(SO₄)(btt)(H₂O)₄]·3H₂O (3·3H₂O). The structures are three-dimensional and consist of cluster-based secondary building units: the pentanuclear {Co₅F₂(tetrazolate)₈(H₂O)₆}, the tetranuclear {Co₄(OH)₂(SO₄)₂(tetrazolate)₆}⁴⁻, and the trinuclear {Co₃(μ₃-OH)(SO₄)₂ (tetrazolate)₃}²⁻ for 1, 2, and 3, respectively. The Ni(II) analogue [Ni₂(H_0.67bdt)₃]·10.5H₂O (4·10.5H₂O) is isomorphous with a fourth cobalt phase, the previously reported [Co₂(H_0.67bat)₃]·20H₂O and exhibits a {M(tetrazolate)_3/2}_∞ chain as the fundamental building block. The dense three-dimensional structure of [Zn(bdt)] (5) consists of {ZnN₄}tetrahedra linked through bdt ligands bonding through N1,N3 donors at either tetrazolate terminus. In contrast to the hydrothermal synthesis of 1–5, the Cd(II) material (Me₂NH₂)₃[Cd₁₂Cl₃(btt)₈(DMF)₁₂]·xDMF·yMeOH (DMF = dimethylformamide; x = ca. 12, y = ca. 5) was prepared in DMF/methanol. The structure is constructed from the linking of {Cd₄Cl(tetrazolate)₈(DMF)₄}¹⁻ secondary building units to produce an open-framework material exhibiting 66.5% void volume. The magnetic properties of the Co(II) series are reflective of the structural building units.