Related Experiment Video
Updated: Jan 19, 2026
Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
Electronic and spin delocalization in a switchable trinuclear triphenylene trisemiquinone bridged Ni3 complex
Yiting Wang1, François Lambert1, Eric Rivière1
1Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Sud, CNRS, Université Paris-Saclay, 91405 Orsay cedex, France. talal.mallah@u-psud.fr.
Abstract:
A trinuclear triphenylene trisemiquinone complex containing paramagnetic NiII is obtained under ambient conditions from the reaction of deprotonated tricatecholate hexahydroxytriphenylene (H6HHTP) with NiII capped with a trispyrazolyl borate tridentate ligand. The magnetic and EPR data are consistent with delocalization of the electronic spin over the three NiII species. The two-electron reduced complex shows an EPR spectrum corresponding to a S = 1/2 species due to a large antiferromagnetic coupling between the radical and only one of the NiII ions highlighting the localization of the electronic spin. No EPR signal is observed for the one- and three-electron reduced species consistent with the closed shell of the bridging ligand.
Related Concept Videos
02:42Valence Bond Theory
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
01:03Atomic Nuclei: Nuclear Spin State Overview
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:57Coordination Number and Geometry