Crystal structure of a mononuclear copper(II) complex with 2-methoxy-N,N-bis(quinolin-2-ylmethyl)ethylamine (DQMEA)

Abstract

Structural characterization of the compound [Cu(C2H3N)(C23H23N3O)](ClO4)2] or [Cu(C2H3N)(DQMEA)](ClO4)2] [DQMEA = 2-methoxy-N,N-bis(quinolin-2-ylmethyl)ethylamine] {systematic name: (acetonitrile)[2-methoxy-N,N-bis(quinolin-2-ylmethyl)ethylamine]copper(II) diperchlorate} by single-crystal X-ray diffraction reveals a complex cation with a tetradentate coordination of the DQMEA ligand along with monodentate coordination of a CH3CN ligand to a single CuII center, with two perchlorate anions providing charge balance. The CuII center has a distorted square-pyramidal geometry in which the nitrogen atoms of the DQMEA and CH3CN ligands occupy the equatorial positions, while the oxygen atom of the DQMEA ligand resides in the axial position with an elongated Cu—O bond. The quinoline ring systems are nearly co-planar in the structure, while the linear CH3CN ligand is tilted significantly below this plane, and the central nitrogen of DQMEA is above it. Within the complex, weak C—H...N hydrogen bonding takes place between the nitrogen of CH3CN and a neighboring quinolyl group. The perchlorate ions are disordered within the structure, but undergo a number of weak intermolecular C—H...O hydrogen-bonding interactions. Additional weak π-stacking interactions between the quinolyl groups of neighboring complexes further stabilize the crystal packing.