We have synthesized two dinuclear dysprosium complexes with the Dy(III)  ions bridged by the neutral bipyrimidine (BPYM) ligand. They crystallized in a  monoclinic and triclinic crystal system with almost the same structural core,  only differing in the lattice solvent molecules. Alternating current susceptibility  measurements revealed that they exhibit significant slow relaxation of  magnetization until 25 K in the absence of a dc field. The single and double  relaxation processes were assigned to one and two types of Dy(III) environments  in the two dimmers, respectively, with barriers of 266 and 345 K under zero  field conditions. The magnetic hysteresis loops of 1 and 2 were both observed  up to 2.5 K. These results have now been published online in <a href="http://pubs.rsc.org/en/Content/ArticleLanding/2016/DT/C6DT01082B">Dalton Trans.</a>