Investigation of the zinc(II) acetylacetonate/benzotriazole reaction system in the presence of bridging N,N '-ligands: Pentanuclear, enneanuclear and polymeric complexes

摘要

The reaction of Zn(acac)(2) with btaH (1,2,3-benzotriazole) in dmf yielded the pentanuclear complex [Zn-5(bta)(6)(acac)(4)(dmf)].dmf (1.dmf). In the presence of pyrazine, the pentanuclear [Zn-5(bta)(6)(acac)(4)(dmf)].3.7dmf (2.3.7dmf) and enneanuclear [Zn-9(bta)(12)(acac)(6)].6dmf (3.6dmf) complexes were whereas in the presence of 4,4'-bpy the 1D coordination polymer [Zn(acac)(2)(4,4'-bpy)](n) (4) formed, was isolated. The molecular structures of 1.dmf and 2.3.7dmf reveal that the [Zn-5] clusters consist of four Zn-II ions which span the corners of a tetrahedron and the fifth resides at its centre. The molecular structure of 3.6dmf reveals that the [Zn-9] clusters consist of two corner sharing tetrahedra and the structure can be described as the addition of two [Zn-5] clusters of 1.dmf and/or 2.3.7dmf followed by the simultaneous abstraction of [Zn(acac)(2)] and dmf molecules: this alternative was accomplished by recrystallization of 1.dmf from dmf which yielded 3.6dmf. Each of the mu(3)-kappa N:kappa N':kappa N '' benzotriazolate ligands in 1.dmf, 2.3.7dmf and 3.6dmf spans an edge of the tetrahedron. The molecular structure of 4 reveals mononuclear [Zn(acac)(2)] units bridged via 4,4'-bpy molecules to ID coordination polymer. Characteristic IR bands of the four complexes are discussed in terms of the coordination modes of the ligands and known structures.