Magnetic Phenomena in Self-Assembled Mono- and Tetranuclear Supramolecular Ni2+ Complexes

Waldmann, Oliver; Hassmann, Jörg; M\", Paul; uller, ; Volkmer, Dirk; Schubert, Ulrich S.; Lehn, Jean-Marie

Abstract:

The magnetization of a novel supramolecular grid structure consisting of four bis~bipyridyl!-pyrimidine ligands and four Ni21 ions and that of the mononuclear analogue Ni~terpy!2 was measured. Magnetic anisotropy was determined from investigations of powder as well as of crystal samples. We provide evidence for an intramolecular antiferromagnetic coupling of the four Ni21 spins of the tetranuclear species with J528 K. The magnetization of the mononuclear complex is typical for a S51 spin with zero field splitting. The magnetization of the tetranuclear grid is discussed in terms of the effective spin Hamiltonian appropriate for Ni21 ions including various higher order exchange terms. In particular, significant indications for a biquadratic term of about J850.5 K is found.

Year:

1998

Type of Publication:

Article

Journal:

Physical Review B

Volume:

58

Pages:

3277 – 3285