In-depth investigation of large axial magnetic anisotropy in monometallic 3d complexes using frequency domain magnetic resonance and ab initio methods: a study of trigonal bipyramidal Co(ii)

Abstract

Symmetry control using DABCO generates a large easy-plane magnetic anisotropy with zero rhombic anisotropy.

Role of Coordination Number and Geometry in Controlling the Magnetic Anisotropy in FeII, CoII, and NiII Single‐Ion Magnets

“…The majority of the Co II five‐coordinated SIMs show D values in the range +35 cm −1 to −20 cm −1 and most of them lie on the positive side of the scale [32] . However, in some of the five‐coordinate Co II complexes, the D values were reported as being more than 40 cm −1 [32a, 33] . The first SIM of Co II was reported by Murugesu and co‐workers in 2011 in which two SqPy Co II species [{ArN=CMe} 2 (NPh)]Co(NCS) 2 ( 21 ) and [{ArN=CPh} 2 (NPh)]Co(NCS) 2 ( 22 ) were synthesised, characterised and both of them showed a D value of approximately 28 cm −1 (see Figure 5 c).…”

Spectroscopic Studies of the Magnetic Excitation and Spin‐Phonon Couplings in a Single‐Molecule Magnet

“…It should be emphasized that this approach was based on the assumption that the Orbach relaxation process is the dominant mechanism in the high‐temperature range. Recent studies on single‐ion magnets (SIMs), those SMMs containing one magnetic center, have shown the shortcomings of such an estimation because other relaxation processes, such as the Raman‐like and direct processes, are also operative in the studied temperature ranges . Analyses of d‐– and f‐SIMs by using the multi‐process model have been reported.…”

“…Recent studies on single‐ion magnets (SIMs), those SMMs containing one magnetic center, have shown the shortcomings of such an estimation because other relaxation processes, such as the Raman‐like and direct processes, are also operative in the studied temperature ranges . Analyses of d‐– and f‐SIMs by using the multi‐process model have been reported. In fact, the Orbach mechanism is not necessarily the dominant process .…”

“…Analyses of d‐– and f‐SIMs by using the multi‐process model have been reported. In fact, the Orbach mechanism is not necessarily the dominant process . In some cases, the Raman process was found to be the only relaxation mechanism at least in the investigated temperature range .…”

“…In some cases, the Raman process was found to be the only relaxation mechanism at least in the investigated temperature range . Thus, a detailed analysis considering all the possible relaxation processes is required to probe the relaxation processes of SMMs . According to the definition of the Orbach mechanism, the energy barrier U eff = 17.0 cm −1 implies a gap of 17.0 cm −1 between the ground KD ( M S = ±3/2) and the excited KD ( M S = ±1/2) in 1 .…”