Oxidation Reaction of 1,2,4,3-Triazaphospholo[4,5-A]Quinolines

Abstract

It is known that oxidatim of 8n, π-electrons heterocycles in the series of 1, 4-dihydro-1,2,3,4,5-tetrazines lead to formation of a stable radical cation salts. In this work the processes of chemical and electrochemical (in MeCn) oxidation of 1-X-1-R1-2-pheny1-5-methyl-6-R2-1,2-dihydro-l,2,4,3-triazapholo[4,5-a] quinolines 1–5 [1] representative of new annelic 8n, π-electrons ststems are presented. For all compounds 1–5 multistep electrochemical oxidation is observed. Products of reversible single electron transfer in low potential range are radical cation, determined by cyclic voltametry method. Compounds of P(III) are oxidized more lightly then corresponding compunds of P(V) (δEp = 0.4 V). Similarly values of oxidation potentials of compounds 1–4 and 2-(2-phenylhydrazino)-4-methylquinolines show that N‒C˭N‒N fragment is reaction center in the processes of electrochemical oxidation. Lone pair (LP) phosphorus carry unimportant contribution in high occupied molecular orbital of 8n, x-electrons hetrocycle, bat to a marked degree stabilizes radical cation and determines behaviour of molecule in chemical reactions. Triazaphospholoquimilines 1–4 are oxidized by oxygen and react with sulphur leading to be the formation phosphoryl- and thiophosphoryl derivatives accordingly.