Synthesis and magnetism of chromium(II) methylphosphonate, Cr-II(MePO(3))center dot H2O: A new weak ferromagnet

A new chromium(II) phosphonate, Cr-II(MePO(3)). H2O, is prepared and characterised; magnetic measurements in the temperature range 100-300 K show a typical Curie-Weiss behaviour with a Curie constant of 2.90(5) emu K mol(-1) and a negative Weiss constant theta of -226(6) K; the thermal variation of the magnetic susceptibility below 60 K depends upon the cooling mode (z.f.c. = zero-field cooled and f.c. = field cooled); the compound is a canted antiferromagnet with the ordering temperature T-N at 35.8(3) K.