Nitric oxide reactivity of copper(II) complexes of bidentate amine ligands

•Cu(II) complexes of propane-1,3-diamine and N-isopropylpropane-1,3-diamine are prepared.•Reduction of the Cu(II) centre of the complexes are observed by nitric oxide in acetonitrile solution.•Spectroscopic studies revealed the formation of [CuII–NO] intermediate prior to the reduction of Cu(II).•This reduction led to the ligand modification in case of both the complexes.

Two copper(II) complexes, 1 and 2 with L1 and L2 [L1 = propane-1,3-diamine; L2 = N-isopropylpropane-1,3-diamine], respectively, were synthesized and characterized structurally. In acetonitrile solution of the complexes, the Cu(II) centre was found to reduce in presence of nitric oxide gas. The formation of [CuII–NO] intermediate prior to the reduction of Cu(II) center was evidenced by UV–Vis, solution FT-IR, X-band EPR studies. This reduction led to the ligand transformation through diazotization at primary amine site in complex 1; whereas, N-nitrosation at the secondary amine site of the ligand was observed in 2. The final organic products were isolated and characterized by spectroscopic studies.

Graphical abstractAddition of nitric oxide in acetonitrile solution of copper(II) complexes of ligands L1 and L2 [L1 = propane-1,3-diamine; L2 = N-isopropylpropane-1,3-diamine], resulted in the formation of [CuII–NO] intermediate prior to the reduction of Cu(II). This reduction led to the ligand transformation through diazotization at primary amine site in complex 1; whereas, N-nitrosation at the secondary amine site of the ligand was observed in 2.Figure optionsDownload full-size imageDownload as PowerPoint slide