Magnetic exchange in trans-Tetraamminedinitronickel(II)

Measurements of the magnetic anisotropy of single crystals, and the high-field magnetization of powder specimens of trans-tetraamminedinitronickel(II), Ni(NH3)4(NO2)2, have been determined. These, and previous susceptibility measurements, are fitted by a one- or two-dimensional Heisenberg exchange model in which the total exchange, ∑ijJij equals about -2 to -3 cm-1. The absolute magnitudes of the single-ion anisotropy parameters, D and E, are required to be smaller than about 2 cm-1. The previous explanation of the low-field magnetic susceptibility as arising from a D value of 10.4 cm-1 is now an inadequate description of all the magnetic data.