Synthesis and structure of a tetranuclear nickel complex of a 40-membered macrocyclic octaamine-tetrathiophenolate ligand

The syntheses and characterization of tetranuclear Ni complexes [(L-2)Ni-4][ClO4](4) (3) and [(L-2)Ni-4(NCS)(4)] (4) of a 40-membered macrocyclic octaamine-tetrathiophenolate ligand (L-2)(4-) are described. Single-crystal X-ray structure analysis of 4 reveals well-separated molecules of the tetranuclear isothiocyanate complex [(L-2)Ni-4(II)(NCS)(4)]. The four Ni centers are arranged in binuclear [N2Ni(mu (2)-SR)(2)NiN2(NCS)(2)] subunits containing distorted square-planar NiN2S2 and distorted octahedral NiN2S2(NCS)(2) sites. The fact that the two isothiocyanate groups at the octahedral Ni site are in trans positions can be ascribed to the large ring size of the macrocycle.