2-Azidoimidazolium Ions Captured by N-Heterocyclic Carbenes: Azole-Substituted Triazatrimethine Cyanines
نویسندگان
چکیده
1,3-Disubstituted 2-azidoimidazolium salts (substituents = methyl, methoxy; anion = PF6) reacted with N-heterocyclic carbenes to yield yellow 2-(1-(azolinylidene)triazen-3-yl)-1,3-R2imidazolium salts (azole = 1,3-dimethylimidazole, 1,3-dimethoxyimidazole, 4-dimethylamino-1methyl-1,2,4-triazole; R = methyl, methoxy; anion = PF6). Crystal structures of three cationic triazenes were determined. Numerous interionic C–H ̈ ̈ ̈F contacts were observed. Solvatochromism of the triazenes in polar solvents was investigated by UV-Vis spectroscopy, involving the dipolarity π* and hydrogen-bond donor acidity α of the solvent. Cyclovoltammetry showed irreversible reduction of the cations to uncharged radicals. Thermoanalysis showed exothermal decomposition.
منابع مشابه
A simple route to phosphamethine cyanines from S,N-heterocyclic carbenes.
Although salts of thiazolium cations are known, many readily prepared iodide salts have eluded spectroscopic and structural characterization; herein, data for a variety of such salts are reported. It has been demonstrated that thiazolium cations can be deprotonated to generate S,N-heterocyclic carbenes and their "electron rich olefin" dimers, but use of the former has been largely overshadowed ...
متن کاملFlexible cycloalkyl-substituted N-heterocyclic carbenes.
The use of two metal systems cis-Pt(NHC)(2)Me(2) and cis-Ir(NHC)(CO)(2)Cl help to highlight the flexibility of a series of cycloalkyl-substituted N-heterocyclic carbene ligands (ICy, ICy(7), ICy(8), ICy(12)). Bond dissociation enthalpies of several N-heterocyclic carbenes (NHCs) in cis-Pt(NHC)(2)Me(2) are estimated. Electronic and steric parameters of the ICy(n) ligands are quantified and discu...
متن کاملZwitterionic borane adducts of N-heterocyclic carbenes from mesomeric betaines of uracil.
We prepared a series of imidazolium-substituted uracil-anions which are members of the class of cross-conjugated heterocyclic mesomeric betaines. They are in tautomeric equilibrium with their N-heterocyclic carbenes, uracil-6-yl-imidazol-2-ylidenes. These carbenes can be trapped by reaction with sulfur, selenium, as well as by triethylborane and triphenylborane, respectively. The latter trappin...
متن کاملDual reactivity of N-heterocyclic carbenes towards copper(II) salts.
Complexes of N-heterocyclic carbenes (NHCs) with copper(II) halogenides are unstable. Upon formation, these complexes decompose to give haloamidinium salts. Contrastingly, O-substituted copper(II) NHC complexes are fairly stable. A series of new five-, six- and seven-membered ring NHC complexes of Cu(OAc)(2) have been synthesised and characterised in the solid state.
متن کاملTriazene formation via reaction of imidazol-2-ylidenes with azides.
Treatment of N-heterocyclic carbenes (as their free carbenes or generated in situ) with alkyl, aryl, acyl or tosyl azides afforded the respective substituted triazenes in excellent yields.
متن کامل