Related Experiment Video
Updated: Nov 2, 2025

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Acyclic diaminocarbene-based Thiele, Chichibabin, and Müller hydrocarbons
Avijit Maiti1, Shubhadeep Chandra2, Biprajit Sarkar2
1Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500046 Telangana India ajana@tifrh.res.in.
Abstract:
Thiele, Chichibabin and Müller hydrocarbons are considered as classical Kekulé diradicaloids. Herein we report the synthesis and characterization of acyclic diaminocarbene (ADC)-based Thiele, Chichibabin, and Müller hydrocarbons. The calculated singlet-triplet energy gaps are ΔE S-T = -27.96, -3.70, -0.37 kcal mol-1, respectively, and gradually decrease with the increasing length of the π-conjugated spacer (p-phenylene vs. p,p'-biphenylene vs. p,p''-terphenylene) between the two ADC-scaffolds. In agreement with the calculations, we also experimentally observed the enhancement of paramagnetic diradical character as a function of the length of the π-conjugated spacer. ADC-based Thiele's hydrocarbon is EPR silent and exhibits very well resolved NMR spectra, whereas ADC-based Müller's hydrocarbon displays EPR signals and featureless NMR spectra at room temperature. The spacer also has a strong influence on the UV-Vis-NIR spectra of these compounds. Considering that our methodology is modular, these results provide a convenient platform for the synthesis of an electronically modified new class of carbon-centered Kekulé diradicaloids.
More Related Videos
09:22Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
06:31Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators
Published on: November 27, 2015
Related Concept Videos
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
Cycloaddition Reactions: Overview
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Cycloaddition Reactions: MO Requirements for Thermal Activation