Issue 45, 2016, Issue in Progress

Bent and twisted: the electronic structure of 2-azapropenylium ions obtained by guanidine oxidation

Abstract

New bis-2-azapropenylium ions are obtained by oxidation of guanidino-substituted aromatic compounds. The dications 12+ (1 = 1,4-bis-tetramethylguanidinobenzene) and 22+ (2 = 1,4-bis-guanidinobenzene) exhibit unexpected bent-twisted structures, that differ from the known 2-azapropenylium ion structures (linear-orthogonal 2-azaallenium ion or bent-planar 2-azaallylium ion), and resemble the structures of carbodicarbenes. Their electronic structure was analysed by a combination of experiments and quantum chemical calculations. The results indicate that the bent-planar structure is disfavoured for steric reasons, while the allene-type linear-orthogonal structure is also disfavoured due to the electron-donating groups that support the bent form. For these reasons a bent-twisted structure is adopted, in which the nitrogen atom is engaged with two different orbitals in π-bonding with the carbon π-system and in a weaker π-interaction with the CN2 group of the guanidino system.

Graphical abstract: Bent and twisted: the electronic structure of 2-azapropenylium ions obtained by guanidine oxidation

Supplementary files

Article information

Article type
Paper
Submitted
19 Feb 2016
Accepted
12 Apr 2016
First published
20 Apr 2016

RSC Adv., 2016,6, 39323-39329

Bent and twisted: the electronic structure of 2-azapropenylium ions obtained by guanidine oxidation

J. Hornung, O. Hübner, E. Kaifer and H. Himmel, RSC Adv., 2016, 6, 39323 DOI: 10.1039/C6RA04494H

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