The effect of antisymmetric exchange on the E.P.R. spectra of coupled pairs of transition metal ions

Abstract

The antisymmetric exchange term (AET) in the exchange spin hamiltonian, d . Sz x Se, can have sizeable effects on the EPR spectra of heterodinuclear transition metal complexes. In this paper we review briefly the symmetry aspects of the AET and give a general formulation for its matrix elements for any pair of Sz, $2 values. The effects of the AET on the E.P.R. spectra are discussed and one case where its presence can be recognized is shown.

Electronic Structures and Reduction Potentials of Cu(II) Complexes of [N,N′-Alkyl-bis(ethyl-2-amino-1-cyclopentenecarbothioate)] (Alkyl=Ethyl, Propyl, and Butyl)

“…1). The spin-Hamiltonian parameters (Table 3) are within the range expected for a CuN 2 S 2 coordination core [13]. The increase in g ʈ and concomitant decrease in A ʈ on going from CuL2 to CuL4 suggests increasing distortion from CuN 2 S 2 planarity in the order CuL3<CuL4 [14].…”

Ising-Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: A Key to Understanding the Formation of Molecular Magnetic Nanowires

“…[16] The angular dependence of the g value of the main line is shown in Figure 5. The minimum g was observed in the rotation b' at % 408 from c*, while the maximum g was observed in the rotation around c* at % 1308 from a.…”

“…In terms of the ligand field approach, the value of the splitting of the t 2g orbitals is D E(d xy ) À E(d xz ), which in the angular overlap formalism may be written as D 4 ep ceq À 2 ep keq À ep ax . [16] It is then clear that the anisotropy of the p interaction has to be carefully considered in order to understand the magnetic behavior of these systems.…”

“…The former have Jahn ± Teller distortions that provide an Ising-type magnetic anisotropy. In the archetypal [Mn 12 O 12 (CH 3 COO) 16 (H 2 O) 4 ], the unique manganese(iii) axes are essentially parallel to each other, [6] giving rise to a zero-field splitting D/k À 0.70 K. Two isomeric forms of [Mn 12 O 12 (p-MeBz) 16 (H 2 O) 4 ] show a different orientation of the elongation axes of manganese(iii) and quite distinct relaxation rates. [7,8] In principle, Ising-type magnetic anisotropy also influences the relaxation of one-dimensional magnets, as suggested by Glauber in the 1960s.…”

Hints for the Control of Magnetic Anisotropy in Molecular Materials

“…Fe''' is a S ion: nevertheless the combined e!ect of spin}orbit coupling and structural distortion is well known to give rise to appreciable zero "eld splitting in coordination complexes of this ion (35). We performed some test calculation assuming two kinds of distortion from octahedral geometry in an intermediate ligand "eld strength (Dq"1460 cm\).…”