The crystal structures of four azido-bridged Zn(ii) complexes based on open-chain diazine Schiff-base ligands

Abstract

Four new Zn(II)-azido polymeric complexes with open-chain diazine Schiff-bases as auxiliary bridging ligands have been synthesized and crystallographically characterized. The differences in the constituents of the auxiliary ligands lead to three different types of polymeric structures. Complex 1, [Zn₂(L¹–H)(N₃)₃]_n (L¹ = 1,4-bis(2-pyridyl)-1-amino-4-methyl-2,3-diaza-1,3-butadiene), and complex 2, [Zn₂(L²–H)(N₃)₃·H₂O]_n (L² = 1,4-bis(2- pyridyl)-1,4-diamino-2,3-diaza-1,3-butadiene), show a similar one-dimensional (1D) coordination polymeric structure in which the building blocks of tetranuclear rings are interlinked by double end-on (EO) azido bridges, resulting in a “chain of rings” topology. Complex 3, {[Zn₁₇(N₃)₂₄(L³–H)₂(L³–2H)₄(CH₃OH)₂]·(CH₃OH)₆·(H₂O)₃}_n (L³ = butanedione monoxime picolinamide hydrazone) has a two-dimensional (2D) structure in which the Zn₁₃ clusters are interlinked by Zn₂ binuclear linkers to result in a (4,4) topology. The remaining complex 4, [Zn₂(L⁴–H)(N₃)₃]_n (L⁴ = 1-(2-pyridyl)-1-amino-4-methyl-4-thiazolyl-2,3-diaza-1,3-butadiene), has a three-dimensional (3D) network with a counterfeit CdSO₄ topology, in which the 1D chains similar to those in complexes 1 and 2 are further interlinked by double EO azido bridges.