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 de
fined by the peak of chi(ac)' They are characterized to be isomorphous, bel
onging to the space group I4(1)22, and canted antiferromagnets below TN The
neutron diffraction study supports the principally antiferromagnetic struc
ture.