Synthesis and properties of (2-pyridyl)alkylamine- and (2-pyridyl)alkylamine–amide-coordinated copper(II) complexes: Structures and non-covalent interactions

Reaction of the ligand N-methyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylethyl)amine (mpppa) with equimolar amounts of [Cu(H2O)6][ClO4]2 or CuCl2 · 2H2O in MeCN afforded mononuclear copper(II) complexes [Cu(mpppa)][ClO4]2 (1) and [Cu(mpppa)Cl2] (2). Crystal structure analysis reveals CuN3O (two pyridyl, an aliphatic amine, and an amide oxygen) coordination in 1 and CuN3Cl2 (two pyridyl, an aliphatic amine, and two chlorides) coordination in 2. Crystal packing diagram of 1 reveals that one of the perchlorate counteranions provides weak coordination to copper(II) centers and in turn the copper(II) centers assume pseudo-six-coordination, generating 1D chain. Notably, one of the copper(II)-coordinated chloride ions in 2 participates in an intramolecular N–H⋯Cl interaction. Intermolecular C–H⋯Cl interactions in the solid state generate helical structure. Spectroscopic (IR, UV–Vis, and EPR) and redox properties of the two complexes have been investigated and compared.

Graphical abstractSynthesis, crystal structure, spectral, redox properties, and secondary interaction studies of two copper(II) complexes [Cu(mpppa)][ClO4]2 (1) and [Cu(mpppa)Cl2] (2) have been done.Figure optionsDownload full-size imageDownload as PowerPoint slide