Synthesis and Characterization of Some Novel Homo- and Hetero-Diradicals of Hydrazyl and Nitroxide Type

Petre Ionita; Floriana Tuna; Marius Andruh; Titus Constantinescu; Alexandru T. Balaban

doi:10.1071/CH06469

RESEARCH ARTICLE

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Synthesis and Characterization of Some Novel Homo- and Hetero-Diradicals of Hydrazyl and Nitroxide Type

Petre Ionita ^A ^E , Floriana Tuna ^B , Marius Andruh ^C , Titus Constantinescu ^A and Alexandru T. Balaban ^D

+ Author Affiliations

- Author Affiliations

^A Institute of Physical Chemistry, 202 Spl. Independentei, Bucharest 060021, Romania.

^B School of Chemistry, University of Manchester, Manchester M13 9PL, UK.

^C Faculty of Chemistry, University of Bucharest, Bucharest 030018, Romania.

^D Marine Sciences Department, Texas A&M University at Galveston, Galveston, TX 77551, USA.

^E Corresponding author. Email: pionita@icf.ro

Australian Journal of Chemistry 60(3) 173-179 https://doi.org/10.1071/CH06469
Submitted: 12 December 2006 Accepted: 20 January 2007 Published: 2 April 2007

Abstract

Starting from the well known stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH; 2a) and its congener 2,2-diphenyl-1-(4-cyano-2,6-dinitrophenyl)hydrazyl 2b, or from their reduced hydrazine counterparts 1a,b, it was possible to obtain the p-quinonoid compounds 4a,b by oxidation with ceric (Ce⁴⁺) sulfate, which by reduction gave the corresponding hydroxyl derivatives 2-phenyl-2-(4-hydroxyphenyl)-1-picrylhydrazine 5a or 2-phenyl-2-(4-hydroxyphenyl)-1-(4-cyano-2,6-dinitrophenyl)hydrazine 5b. These hydroxyl derivatives (5a,b) react with 4-carboxy-TEMPO or 2,2-diphenyl-1-(4-carboxy-2,6-dinitrophenyl)hydrazine to form the corresponding esters 6a,b or 8a,b. These esters (6a,b and 8a,b) lead to the hybrid hetero diradicals (nitroxide–hydrazyl type) 7a,b or homo biradicals (hydrazyl–hydrazyl type) 9a,b by oxidation with lead dioxide or potassium permanganate. The new compounds were characterized by UV-vis, NMR, EPR, and MS analysis, and their magnetic behaviour was investigated.

Acknowledgment

Financial support from CNCSIS (Grant 5/2006) is gratefully acknowledged.

References

Synthesis and Characterization of Some Novel Homo- and Hetero-Diradicals of Hydrazyl and Nitroxide Type

Abstract

Acknowledgment

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