LAUSR

Abstract 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]∙(ClO4)4 (1), having a Cu4O4 cubane core is reported here. 1 was synthesized hydrothermally at 80 °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 J1 =  − 28.0 cm−1, J2 = +72.2 cm−1, and J3 =  − 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.