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

The new ligand N ‐methylanthraniloyl(4‐ethylthiosemicarbazide) H 2 L was synthesized by the treatment of anthranilic acid hydrazide and ethyl isothiocyanate in absolute ethanol. The composition and structure of H 2 L were characterized by spectroscopic methods such as ESI MS, IR, 1 H and 13 C{ 1 H} NMR spectroscopy as well as SCXRD. Reaction of H 2 L and mixture of [Cu(MeCN) 4 ](PF 6 ) and o ‐phenanthroline in methanol gave rise to a cationic Cu(II) trinuclear complex, which could be separated as PF 6 – salt with the composition of [Cu 3 (L) 2 ( o ‐phen) 2 ](PF 6 ) 2 . The spectroscopic and X‐ray crystallographic data analyses demonstrated that H 2 L deprotonates hydrazide protons and the resulting dianion {L 2– } 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 {L 2– } via ( O , N 2 ) 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 , N 1 , N amine ) and ( N , N ) donor sets belonging {L 2– } and o ‐phenanthroline, respectively.