Symmetric and asymmetric trinuclear cores in novel μ-alkoxo-bridged mixed-metal CuII2ZnII complexes:: synthesis from zerovalent copper and zinc oxide, structure and magnetism

Three novel heterotrinuclear complexes, [Cu2Zn(NH3)Cl-3(Me(2)Ea)(3)] 1, [Cu2Zn(NH3)Br-3(Me(2)Ea)(3)] 2 and [Cu2Zn(NCS)(3)(Me(2)Ea)(3)]. CH3CN 3 (Ea=NCH2CH2O), have been prepared using zerovalent copper, zinc oxide, an ammonium salt and 2-dimethylaminoethanol (HMe(2)Ea) in air. Crystallographic investigations reveal that they contain trinuclear symmetric (3) and asymmetric (1 and 2) cores, that consist of a portion of a distorted cube in which alternate corners are metal and non-metal atoms and one corner metal site is vacant. The chemical difference between the three compounds produces changes in the coordination environment of the metal atoms and their overall crystal structures. Cryomagnetic measurements reveal that the overall antiferromagnetic coupling in the symmetric complex 3 is stronger compared to the other two complexes, despite their slightly shorter copper-copper separations.