[Tris(o-iminosemiquinone)cobalt(III)]—a radical complex with an St = 3/2 ground state

Abstract

Owing to their topology, three iminosemiquinone radical ligands couple in a ferromagnetic fashion, mediated by a low-spin Co(iii) ion.

Novel CuIII Bis‐1,2‐dichalcogenene Complexes with Tunable 3D Framework through Alkaline Cation Coordination: A Structural and Theoretical Study

“…Experimental and theoretical evidence has been reported on de-aromatization of the benzene rings to give an open-shell o-semiquinonate type ligand, and the singlet diradical ground states of some neutral complexes have been characterized (Schemes 1 and 2). [13] Thus, the contribution of the ligands to the HOMO and their role upon oxidation of the complex, often referred as innocent or noninnocent character of the ligands, is still under discussion. Many different dithiolene-type ligands have been studied, but only a small amount of work was devoted to Se-containing ligands.…”

“…Two strategies have been employed for this purpose: increasing the number of peripheral sulfur atoms associated with the ligand framework to strengthen the intermolecular interactions through more S¥¥¥S contacts, and changing from sulfur ligands to selenium analogues. [4] The greater spatial extension of the Se 4d orbitals compared [ 13 C NMR and IR spectroscopy, electronic absorption, elemental analysis, cyclic voltammetry (CV), and X-ray crystallography. Electrical conductivity measurements on single crystals show that these salts exhibit insulating behavior.…”

The Effect of Ligand Architecture on the Structure and Properties of Nickel and Copper Complexes of Amide‐Based Macrocycles

“…[11][12][13] In this category, the ligand system based on an ophenylenediamine skeleton containing additional nitrogen, oxygen and sulfur donors has shown quite interesting results. [11][12][13] Thus, the redox non-innocence of the o-phenylenediamine fragment [NH(C 6 H 4 )NH] when coordinating to a metal ion has been a major focus of study.…”

Exchange Interactions and Covalency in Dinuclear Complexes of Iron(III) and Gallium(III) Containing the Redox‐Noninnocent Ligand 1,2‐Bis(3,5‐di‐tert‐butyl‐2‐hydroxyphenyl)oxamide

“…When such a radical ligand (S rad ϭ 1 / 2 ) is coordinated to a paramagnetic transition metal ion with an incompletely filled t 2g subshell, very strong intramolecular antiferromagnetic exchange coupling between the radical spin and the t 2g n configuration is observed. Thus, [Cr III (L ISQ ) 3 ], [3] containing a Cr III ion with t 2g 3 configuration and three (L ISQ ) 1Ϫ· radical anions, possesses an S t ϭ 0 ground state, whereas its cobalt() analogue [1] (t 2g 6 ) possesses an S t ϭ 3 / 2 ground state because the three ligand spins couple ferromagnetically.…”

“…(1) Thus, the spins of the two ferric ions in 2 are weakly antiferromagnetically coupled; the complex possesses an EPR-silent S t ϭ 0 ground state which, however, is not very well isolated from paramagnetic excited states. Thus, the applied field can induce a weak magnetic moment even at 2 K. This is best observed in multi-field measurements with variable-temperature data sampled on a 1/T scale (inset of that are typical for high-spin ferric ions (Figure 4, top).…”