Structures and Magnetic Properties of Dinuclear Copper(II) Complexes Containing a Bulky Diamine Ligand, 1,2-Dipiperidinoethane

Abstract

Abstract A reaction of copper(II) perchlorate with a sterically hindered diamine, 1,2-dipiperidinoethane (dipe), yields two dinuclear complexes: di-μ-hydroxo dinuclear complex [{Cu(ClO4)(dipe)(μ-OH)}2] (1) and di-μ-alkoxo dinuclear complex [{Cu(ClO4)(dipe-O)}2] (2) (dipe-O− is 1-(2-piperidinoethyl)piperidin-3-olate which was newly obtained in this work). The structures of complexes 1 and 2 were confirmed by X-ray crystallography. Complex 2 is meso form containing (R)- and (S)-dipe-O−. Dipe-O− acts as a tridentate ligand with an N,N,O-donor set and bridges two copper(II) ions through the oxygen atom. The oxygen atom is incorporated into dipe from atmospheric molecular oxygen during the reaction of dipe with copper ion. The temperature dependences of χmT values were different between 1 and 2 depending on the bridging structures. Complex 1 shows ferromagnetic interaction and the value of 2J = 117 cm−1 is in agreement with that predicted from the ∠Cu–O–Cu bridging angle of 96.9°. Complex 2, the bridging angle of which is 100.59°, shows a strong antiferromagnetic interaction (−2J > 400 cm−1). The singlet–triplet energy gap for complex 2 was estimated from DFT calculation.