An unprecedented antiferromagnetic exchange mediated by two -O-Zn-O- bridges, with singlet-triplet splitting J = 35.0 cm(-1), was observed between two copper centers separated by 5.7062(9) (A) over circle in the heterometallomacrocyclic diethanolamine (H2L) complex [Cu2Zn2(NH3)(2)Br-2(HL)(4)]Br(2)center dot CH3OH.
Buvaylo, E. A., Kokozay, V. N., Vassilyeva, O. Y., Skelton, B., Jezierska, J., Brunel, L. C., & Ozarowski, A. (2005). A Cu-Zn-Cu-Zn heterometallomacrocycle shows significant antiferromagnetic coupling between paramagnetic centres mediated by diamagnetic metal. Chemical Communications, 39, 4976-4978. https://doi.org/10.1039/b509810f