Abstract
Magnetic phase transitions of PM2·CoCl2, PM2·CoBr2, and PM2·FeCl2 (PM = pyrimidine) were observed at T N = 4.4, 4.7, and 6.1 K, respectively, as defined by the peak of χac′. They are characterized to be isomorphous, belonging to the space group I4122, and canted antifer-romagnets below T N. The neutron diffraction study supports the principally antiferromagnetic structure.