Structure and magnetism of mono-, di-, and trinuclear benzoato cobalt(II) complexes

Three cobalt(II) – benzoato (bz) complexes have been prepared and structurally characterized. In the mononuclear complex trans-[Co(bz)2(H2O)2(nca)2] the benzoato ligand is unidentate (nca = nicotinamide). The dinuclear complex [(μ2-bz)4{Co(qu)}2] is a structural analog of the copper acetate (qu = quinoline) where four bidentate benzoato ligands link two cobalt(II) pentacoordinate centers. The trinuclear complex of the composition [Co3(bz)6(inca)6] contains a central hexacoordinate {(bz)2Co(inca)2(bz)2} unit in which the bidentate benzoato ligands held the central and peripheral cobalt(II) centers (inca = iso-nicotinamide); the peripheral hexacoordinate {(bz)Co(inca)2<} units contain the terminal benzoato ligand in its bidentate function. The magnetic susceptibility data down to T = 2 K and the magnetization data up to B = 7 T reveal a considerable magnetic anisotropy due to the single-ion zero-field splitting.

Mononuclear, dinuclear, and trinuclear cobalt(II) complexes containing benzoato ligands have been prepared and structurally characterized. The magnetic data confirm a considerable magnetic anisotropy due to the single-ion zero-field splitting term D.Figure optionsDownload as PowerPoint slideHighlights
► The mononuclear Co(II) complex refers to a square bipyramid.
► The dinuclear complex possesses pentacoordinate Co(II) centers linked by the benzoato ligands.
► The trinuclear complex is a linear assembly of Co(II) centers held by the benzoato ligands.
► The electronic spectra of mononuclear and trinuclear complexes match the octahedral pattern.
► Magnetic susceptibility and magnetization data show large zero-field splitting.