Chain Compounds Based on Paddle-wheel Copper(II) Carboxylate Bearing Four Nitroxide Radicals

Masahiro Mikuriya,Renny Indrawati,Makoto Handa,Kazuyuki Yokota,Daisuke Yoshioka,Masafumi Fukuzaki,Chizu Nakamura,Shizuka Matsubara,Rieko Hashido

doi:10.3390/magnetochemistry4020022

Abstract

Chain compounds of paddle-wheel Cu2-clusters of 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (Hcaproxy) and 4-carboxy-2,2,6,6-tetramethylpiperidinyloxy (Hcatempo) and N,N’-bidentate ligands (L = 4,4′-bipyridine (4,4′-bpy), 1,2-bis(4-pyridyl)ethane (bpe), trans-1,2-bis(4-pyridyl)ethylene (bpel), 4,4′-dipyridyl disulfide (pds), 1,4-diazabicyclo[2.2.2]octane (dabco), and pyrazine (pyz)), [Cu2(caproxy)4(L)]n, and [Cu2(catempo)4(L)]n, were synthesized and characterized by elemental analysis, infrared and UV-vis spectra and temperature dependence of magnetic susceptibilities (4.5–300 K). The crystal structures of [Cu2(caproxy)4(pds)]n, [Cu2(catempo)4(4,4′-bpy)]n, and [Cu2(catempo)4(bpe)]n revealed zigzag or linear chains consisting of alternate arrangement of the dinuclear cluster bearing four nitroxide radicals and N,N’-bidentate ligand. Temperature dependence of magnetic susceptibilities showed a considerable antiferromagnetic interaction between the two copper(II) ions within the dinuclear cluster, and weak antiferromagnetic interaction between the dinuclear clusters and/or the radical and dinuclear cluster.

Highlights

Copper acetate is one of the old-fashioned metal complexes with a paddle-wheel-like or lantern-like cluster and has attracted much attention since the discovery of the unique dinuclear structure with antiferromagnetic spin-coupling [1,2,3,4,5,6,7]
We have engaged in the synthesis of copper acetate analogues and their coordination polymer complexes [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24]
We reported that a chain compound of copper(II) benzoate with pyrazine shows an adsorption property for N2 because of the hydrophobic micropore that is formed by the aromatic benzoate groups [12,24]

Summary

Introduction

Copper acetate is one of the old-fashioned metal complexes with a paddle-wheel-like or lantern-like cluster and has attracted much attention since the discovery of the unique dinuclear structure with antiferromagnetic spin-coupling [1,2,3,4,5,6,7]. We have engaged in the synthesis of copper acetate analogues and their coordination polymer complexes [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24]. We reported that a chain compound of copper(II) benzoate with pyrazine shows an adsorption property for N2 because of the hydrophobic micropore that is formed by the aromatic benzoate groups [12,24]. This is an interesting feature of this type of coordination polymers. Many trials to prepare the chain adduct of catempo system with pyrazine were unsuccessful, resulting in recovery of the parent complex, which was confirmed by elemental analysis and infrared spectra

Infrared Spectra of Chain Compounds

Electronic Spectra of Chain Compounds

Materials and Methods

Conclusions