Formation of High-Spin States (<i>S</i> = 3/2 and 2) in Linear Oligo- and Polyarylamines

This article describes the study of a linear trimer and three polyarylamines <b>PB1–3</b> containing a 3,4′-biphenyl ferromagnetic coupler. The synthesis of the model compound (trimer) and the polymers has been presented. The formation of radical cations was studied using electrochemical and optical (UV–vis) methods. The chemical oxidation of these compounds leads to the creation of high-spin states, evidenced by pulsed EPR nutation spectroscopy. A quartet spin state is observed for the trimer model compound, and its <i>J</i> exchange coupling constant has been measured experimentally (<i>J</i>/<i>k</i> = 11.8 K) and compared quantitatively to DFT calculations. Most importantly, quartet and quintet spin states have been formed for <b>PB3</b> and <b>PB2</b>, respectively. These last two doped polymers thus exhibit the highest spin states observed to date for linear polyarylamine compounds

Ferromagnetic Spin Coupling through the 3,4′-Biphenyl Moiety in Arylamine OligomersExperimental and Computational Study

This report describes the study of a dimer <b>d</b>^<b>2+</b> and a linear trimer <b>t</b>^<b>3+</b> of amminium radical cations coupled by 3,4′-biphenyl spin coupling units. The synthesis of the parent diamine and triamine and their optical and electrochemical properties obtained by UV–visible and cyclic voltammetry are presented. The chemical doping of the parent diamine <b>d</b> and triamine <b>t</b> was performed quantitatively to obtain samples containing the corresponding dimer <b>d</b>^<b>2+</b> and trimer <b>t</b>^<b>3+</b> in almost pure high-spin states as evidenced by pulsed EPR nutation spectroscopy. The <i>J</i> coupling constants of the corresponding <i>S</i> = 1 and <i>S</i> = 3/2 spin states were measured (<i>J</i>/<i>k</i> = 135 K) and compared quantitatively to DFT calculations