A New 1-1-4 Pattern Of Magnetic Exchange Interactions In A Cubane Core Tetranuclear Copper (Ii) Complex

The dependence on structure of the magnetic exchange coupling between copper (II) ions in complexes containing Cu4O4 cubane units has been the subject of several previous studies. A new example of a tetranuclear copper (II) complex, [{Cu(OH)(phen)}(4)]center dot(ClO4) 4 (1), having a Cu4O4 cubane core is reported here. 1 was synthesized hydrothermally at 80 degrees C using 1,10-phenanthroline (phen) as a ligand in a mildly acidic water/ethanol solution (pH = 4.8-5.3) and structurally characterized by single crystal X-ray crystallography. The best fit to the magnetic data in the 2-300 K temperature range was obtained with a previously unreported 1 + 1 + 4 model for the exchange coupling among the copper (II) ions with J(1) = - 28.0 cm(-1), J(2) = +72.2 cm(-1), and J(3) = - 15.3 cm(-1). The model corresponds to one medium, one short, and four long exchange pathways. The overall predominant antiferromagnetic exchange leads to a singlet total spin ground state. (C) 2021 Elsevier Ltd. All rights reserved.