Copper(II)/di-2-pyridyl ketone chemistry: A triangular cluster displaying antisymmetric exchange versus an 1D coordination polymer

Abstract

The systematic study of the reaction system copper(II) perchlorate/di-2- pyridyl ketone, (py)2CO, provided access to the new trinuclear compound [Cu3{(py)2C(OMe)(O)}3(H 2O)](ClO4)3·MeOH·0.6H 2O (1·MeOH·0.6H2O), and the 1D coordination polymer [Cu2{(py)2C(OEt)(O)}(HCO2) 2(ClO4)(MeCN)]n (2) bearing the anionic hemiketal forms of (py)2CO. Both compounds were prepared from reactions of Cu(ClO4)2·6H2O with the ligand, in the presence of NEt3 in MeOH (1) or MeCN/TEOF (2), where TEOF is triethylorthoformate. Compound 1 possesses a triangular metal topology representing an example of a non-oxido/hydroxido/methoxido-centered Cu 3 species. Compound 2 is based on dinuclear units linked through HCO2- groups forming an 1D chain. EPR spectra and variable temperature dc magnetic susceptibility studies on powdered polycrystalline samples of 1 revealed the presence of strong antiferromagnetic interactions between the metal centers leading to an S = 1/2 ground state. The magnetic susceptibility data were fit using a model including antisymmetric exchange interactions and the antisymmetric exchange vector parameter GZ value has been determined. © 2013 Elsevier Ltd. All rights reserved.