Synthesis and structural characterization of N‐methylanthraniloyl‐ (4‐ethylthiosemicarbazide) and its Cu(II) trinuclear complex

The new ligand N‐methylanthraniloyl(4‐ethylthiosemicarbazide) H2L was synthesized by the treatment of anthranilic acid hydrazide and ethyl isothiocyanate in absolute ethanol. The composition and structure of H2L were characterized by spectroscopic methods such as ESI MS, IR, 1H and 13C{1H} NMR spectroscopy as well as SCXRD. Reaction of H2L and mixture of [Cu(MeCN)4](PF6) and o‐phenanthroline in methanol gave rise to a cationic Cu(II) trinuclear complex, which could be separated as PF6– salt with the composition of [Cu3(L)2(o‐phen)2](PF6)2. The spectroscopic and X‐ray crystallographic data analyses demonstrated that H2L deprotonates hydrazide protons and the resulting dianion {L2–} acts as bridging ligand of which most potential donor atoms form stable chelates with Cu(II) ions. In particular, the central Cu(II) ion coordinates with two dianions {L2–} via (O, N2) donor sets, thereby adopting a distorted square planar coordination mode with trans configuration. While each of two terminal Cu(II) ions is five‐coordinate with the coordination sphere composed of (S, N1, Namine) and (N,N) donor sets belonging {L2–} and o‐phenanthroline, respectively.