Syntheses, crystal structures, and magnetic properties of four novel Cu(I/II) complexes

Four coordination compounds CuIICuI(O2N-ipO)(4,4′-bpy) (1), [CuII6(O2N-ipO)4btp(H2O)8]·6H2O (2), [CuII12(O2N-ipO)8(bth)4(H2O)10]·2H2O (3), and [CuII18(O2N-ipO)12(btp)3(H2O)18(EtOH)6]·13H2O (4) (4,4′-bpy = 4,4′-dipyridyl, btp = 1,3-bis(1,2,4-triazol-1-yl)propane, bth = 1,6-bis(1,2,4-triazol-1-yl)hexane and O2N-ipO = deprotonated 5-NO2-2-hydroxyisophthalic acid, Chart 1) were synthesized and crystallographically characterized. The common building unit [Cu2(O2N-ipO)2] (O2N-ipO = deprotonated 5-NO2-2-hydroxyisophthalate, in-situ formed in the reaction of 5-NO2-1,2,3-benzenetricarboxylic acid (O2N-btcH3) with CuCl2·2H2O under hydrothermal conditions) features a diamond-shaped dinuclear motif, in which two Cu atoms are bridged by the deprotonated 2-hydroxo groups from different O2N-ipO ligands. Compound 1 exhibits a three-dimensional (3D) wave-like structure composed of [CuII2(O2N-ipO)2]2− and [CuI2(4,4′-bpy)2]2+ subunits, while 2 displaying a 1D alternate double-chain structure based on units of [CuII2(O2N-ipO)2] and [CuIINO4]. Compounds 3 and 4 are discrete polynuclear species featuring a dodeca- and a octadeca-nuclear core based on units of [CuII2(O2N-ipO)2] and [CuIINOn], respectively. These compounds were further characterized by elemental analyses, FTIR, PXRD and thermogravimetric analyses. In addition, we studied their magnetic properties via direct current magnetic susceptibility measurements.

Four new coordination compounds of Cu(I/II) with 5-O2N-2-hydroxyisophthalate (O2N-ipO) ligand were synthesized and crystallographically characterized, and their magnetic properties were investigated. These complexes share the same dinuclear motif of [Cu2(O2N-ipO)2]2− whose ligand O2N-ipO was produced in situ during the hydrothermal synthesis using 5-O2N-1,2,3-benzenetricarboxylic acid as the starting ligand. Antiferromagnetic interactions were found in these compounds.Figure optionsDownload as PowerPoint slideHighlights
► Four new compounds of Cu(I/II) with in-situ synthesized O2N-ipO from O2N-btcH3 were obtained.
► The necessity of Cu(II) for the in-situ ligand transformation was found during the synthesis.
► It was found that under high-pH conditions, O2N-btcH3 would undergo in-situ decarboxylation reaction.
► The magnetic characterization and simulation was performed based on diamond-shaped dinuclear motif [CuII2(O2N-ipO)2].