Novel hetero-polynuclear metal complexes (CuL)3[Mn(NCS)5]2 and (NiL)3[Mn(NCS)5]2 containing trigonal bipyramidal geometric [Mn(NCS)5]3− as bridging ligand

Two thiocyanate-bridged hetero-pentanuclear complexes (CuL)3[Mn(NCS)5]2(1) and (NiL)3[Mn(NCS)5]2(2) have been successfully synthesized and characterized by X-ray single crystal diffraction, elemental analysis, IR, TGA and magnetic measurements. (L = N-dl-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene). Single crystal structure analysis indicates that complex 1 and 2 have similar structures in which the Mn(II) atom is five-coordinated in a trigonal bipyramidal geometry by five N atoms from five thiocyanate ligands. The Cu(II) and Ni(II) both show two different coordination environments, square pyramidal and distorted octahedron. Three Cu(II) (or Ni(II)) ions and two Mn(II) ions are bridged by the end-to-end thiocyanate ligands to form pentanuclear entities. The pentanuclear entities are further linked to 3D framework by the hydrogen bonds. The variable-temperature magnetic measurements for 1 indicated weak antiferromagnetic interaction between the Cu(II) and Mn(II) ions.

Graphical abstractThe thiocyanate-bridged pentanuclear (CuL)3[Mn(NCS)5]2(1) and (NiL)3[Mn(NCS)5]2(2) are isomorphic, and Mn(II) is coordinated by five N atoms from five thiocyanate ligands in a trigonal bipyramidal geometry, which is a novel coordination mode and observed in the complexes for the first time.Figure optionsDownload full-size imageDownload as PowerPoint slide