Complete set of magnetic parameters in a novel nickel(II) chelate

A theoretical analysis of powder magnetic data based on the diagonalization of the spin Hamiltonian matrices is outlined. The first and second derivatives of the eigenvalues are determined from the fourth-order polynomial fit; they enter the van Vleck formula for the paramagnetic susceptibility. The procedure is capable of subtracting the complete set of magnetic parameters from powder susceptibility data. A five-member Ni(II) metallocycle (S=1) was investigated by SQUID measurements down to 2 K and a substantial drop of the χT curve below 25 K was found. A reconstruction of the components of the magnetic susceptibility was done. An independent fitting procedure using four fundamental magnetic parameters gave Λxx=42.8±0.1, Λyy=49.9±0.1, Λzz=26.6±0.1 au and zJ/hc=−2.06±0.01 cm−1. These data reproduce the enlarged set of magnetic parameters well so that a selfconsistency of magnetic parameters is proven.