A simple route to phosphamethine cyanines from S,N-heterocyclic carbenes

Dalton Trans. 2016 Feb 7;45(5):2138-47. doi: 10.1039/c5dt03019f. Epub 2015 Nov 4.

Abstract

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 by that of the more common N-heterocyclic carbenes. We report herein that the deprotonation of thiazolium iodides and their subsequent reaction with a conveniently prepared triphosphenium precursor grants phosphamethine cyanine cations with solid-state geometry and electronic structure unlike those of NHC-stabilized cations. Protection of the phosphorus atom in such ions with elemental sulfur provides an air- and moisture-stable dithiophosphinium salt.

Publication types

  • Research Support, Non-U.S. Gov't