Theoretical study of the magnetic anisotropy and magnetic tunnelling in mononuclear Ni(ii) complexes with potential molecular magnet behavior

Abstract

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Magnetic Anisotropy in “Scorpionate” First‐Row Transition‐Metal Complexes: A Theoretical Investigation

“…Owing to the large distortion in [MnTpCl] + , the first transition is decreased in the C s structure and the D value is positive. In addition, the value of ξ for [FeTpCl] is nearly three times larger than E JT , hence the SOC dominates over vibronic coupling 12c. The differences between the MAEs in the C 3 v and low‐symmetry structures are less pronounced in comparison with the unsubstituted analogues due to the quenching of JT distortion upon substitution.…”

“…Tp − is a rigid chelate ligand, and the JT distortion is manifested through changes in the ClMN angles, denoted as α and β and illustrated in Figure 8. Although JT distortion leads to a reduction in the MAE, it was previously shown that it could be quenched by the careful choice of ligands 12c. A practical way to suppress JT distortion in the [MnTpCl] + and [FeTpCl] complexes could be the substitution of the hydrogen atoms on the pyrazolyl rings with voluminous groups.…”

“…It has been shown that all common molecular properties, for example, zero‐field splitting,10g, 12 Zeeman interactions,13 hyperfine splitting,13 Jahn–Teller (JT) effects,14 magnetic exchange coupling,15 shielding constants,16 electronic structure and transitions in f elements,12a, 17 and f–d transitions,8a, 18 can be calculated by this procedure. LF‐DFT proved to be particularly good for determining the MAEs in trigonal‐bipyramidal Ni 2+ complexes12c and complexes of Fe + 10i. In both cases, LF‐DFT gave excellent agreement with highly accurate MRCI12c and CASPT210i calculations, respectively.…”

“…LF‐DFT proved to be particularly good for determining the MAEs in trigonal‐bipyramidal Ni 2+ complexes12c and complexes of Fe + 10i. In both cases, LF‐DFT gave excellent agreement with highly accurate MRCI12c and CASPT210i calculations, respectively. Furthermore, LF‐DFT was able to calculate the very low experimentally observed value of MAE in the acetylacetonate ⋅ Cr 3+ complex, and it was even appropriate for calculations of the MAEs in excited states 19.…”

“…The angular momentum is unquenched and Equation (4) is no longer valid 24. Thus, it is necessary to develop new Hamiltonians12c to describe the situation that exists, for example, in complexes involving Mn 3+ and Fe 2+ ions (see Figure 2). In both systems, the ground‐state term is 5 E and it experiences first‐order splitting by spin–orbit coupling 21.…”