Ambient-Stable Bis-Azoaromatic-Centered Diradical (L-center dot)M(L-center dot)] Complexes of Rh(III): Synthesis, Structure, Redox, and Spin-Spin Interaction

Roy, Sima and Pramanik, Shuvam and Patra, Sarat Chandra and Adhikari, Basab and Mondal, Abhishake and Ganguly, Sanjib and Pramanik, Kausikisankar (2017) Ambient-Stable Bis-Azoaromatic-Centered Diradical (L-center dot)M(L-center dot)] Complexes of Rh(III): Synthesis, Structure, Redox, and Spin-Spin Interaction. In: INORGANIC CHEMISTRY, 56 (21). pp. 12764-12774.

PDF INO_CHE_56-21_12764_2017.pdf - Published Version Restricted to Registered users only Download (3MB) | Request a copy

Abstract

Bis-azoaromatic electron traps, viz. 2-(2-pyridylazo)azoarene 1, have been synthesized by colligating electron-deficient pyridine and azoarene moieties, and they act as apposite proradical templates for the formation of stable open-shell diradical complexes (1(center dot-))Rh-III(1(center dot-))](+) (2](+)), starting from the low-valent electron reservoir Rh-I]. The less stable monoradical Rh-III(1(center dot-))Cl-2(PPh3)(3)] (3) has also been isolated as a minor product. These p-radical complexes are multiredox systems, and the electron transfer processes occur exclusively within the pincer-type NNN ligand backbone 1. Molecular and electronic structures of the diradicals and monoradicals have been ascertained with the aid of X-ray diffraction, electrochemical, spectroelectrochemical, and spectral (electronic, IR, NMR, and EPR) studies. In the diradicals 2](+), the orthogonal disposition of two ligand pi orbitals linked via a closed-shell metal center (t(2)(6)) impedes significant coupling between the radicals. Indeed, the observed magnetic moment of 2a](+) lies near similar to 2.3 mu(B) over the temperature range 50-300 K. A very weak antiferromagnetic (AF) intramolecular spin-spin interaction between two ligand pi arrays in (1(center dot-))Rh-III(1(center dot-))](+) have been found experimentally (J approximate to -5 cm(-1)), and this is further substantiated by density functional theory (DFT) calculations at the (U)B3LYP/6-31G(d,p) level.

Item Type:	Journal Article
Publication:	INORGANIC CHEMISTRY
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	01 Dec 2017 06:48
Last Modified:	01 Dec 2017 06:48
URI:	http://eprints.iisc.ac.in/id/eprint/58350

Actions (login required)

View Item