Mixed azide-carboxylate bridged tri- and tetranuclear MnII clusters in coordination polymers derived from a zwitterionic dicarboxylate ligand: Structures and magnetism

Yu Ma, Kun Wang, En Qing Gao, You Song

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40 Scopus citations

Abstract

Two MnII coordination polymers with azide and the zwitterionic dicarboxylate ligand bis(N-carboxymethyl-4-pyridinium) (bcp) were synthesized, and structurally and magnetically characterized. They are formulated as [Mn 3(bcp)2(N3)2(SO4) 2(H2O)4]·6H2O (1) and [Mn4(bcp)2(N3)8(H2O) 2]·4H2O (2). Compound 1 contains anionic linear [Mn3(N3)2(COO)4(SO4) 2(H2O)4]4- units with simultaneous μ2-EO (end-on) azide, sulfate and carboxylate bridges, while compound 2 contains [Mn4(COO)4(N3) 8(H2O)2]4- clusters with mixed μ2-EO azide, μ3-EO azide and carboxylate bridges. In these compounds, the anionic tri- or tetranuclear units are linked into coordination chains by the cationic bipyridinium spacers, and are also hydrogen bonded into chains by double O-H⋯O bridges. Magnetic analyses were carried out on temperature-variable susceptibility data for both compounds, and also on isothermal magnetization data for 1. It is revealed that all the mixed double and triple bridges, [(EO-N3)(COO)(SO4)] in 1, [(COO)(EO-N3)2] and [(COO)(EO-N3)] in 2, transmit antiferromagnetic coupling between MnII ions. The [(EO-N3)2] bridge in 2, with Mn-N-Mn = 96.6°, also transmits antiferromagnetic coupling, providing the first example in the antiferromagnetic regime predicted theoretically for double EO-azide bridges between MnII ions. The double hydrogen bonding [(O-H⋯O) 2] bridges in both compounds induce weak antiferromagnetic interactions.

Original languageEnglish
Pages (from-to)7714-7722
Number of pages9
JournalDalton Transactions
Volume39
Issue number33
DOIs
StatePublished - 7 Sep 2010

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