Related Experiment Video
Updated: Mar 29, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Investigating Disjoint Non-Kekulé Diradicals with Quantum Monte Carlo: The Tetramethyleneethane Molecule through the
Matteo Barborini1, Emanuele Coccia2
1S3 Research Center, CNR-NANO , Via Campi 213/a, 41125 Modena, Modena, Italy.
Abstract:
Disjoint non-Kekulé molecules are diradicals that present two independent radical centers and can violate Hund's rule, according to which the ground state should have triplet spin symmetry. The prototype of this class of systems is the tetramethyleneethane (TME) molecule for which indeed ion photoelectron spectroscopy (IPS) experiments revealed the singlet (1)A state to be more stable than the triplet (3)Bu. In this work we investigate the potential energy curves of the two spin states of TME and of the two anionic states of TME(-) ((2)A and (2)B1) as a function of the torsion of the central dihedral angle, with quantum Monte Carlo methods and a Jastrow Antisymmetrized Geminal Power wave function. Through ab initio geometrical optimizations we study the possible structural interconversions between the states, finding results which are in full agreement with the IPS experimental data.
More Related Videos
10:34Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow
Published on: April 24, 2014
08:54Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid
Published on: January 25, 2020
Related Concept Videos
Radicals: Electronic Structure and Geometry
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
Radical Reactivity: Overview
Radical Reactivity: Steric Effects
Along with electronic...
Woodward–Hoffmann Selection Rules and Microscopic Reversibility
Radical Anti-Markovnikov Addition to Alkenes: Overview