Stable N-Phosphorylated 1,2,4-Triazol-5-ylidenes: Novel Ligands for Metal Complexes

Abstract

Synthetic routes to novel N-phosphorylated 1,2,4-triazolium salts have been developed. Treatment of the specified salts with strong base produces new stable Nphosphorylated 1,2,4-triazol-5-ylidenes, which add Se in two stages (first at the carbene carbon and then at phosphorus) and rearrange to C-phosphorylated triazoles with heating. The capacity of such N-phosphorylated triazol-5-ylidenes to act as bidentate ligands toward transition-metal centers has also been demonstrated; in particular, the formation of two dinuclear silver carbene complexes is described herein. The structures of one representative carbene and of one carbene complex were determined by an X-ray study.

Investigation of N‐ and C‐Phosphanylation of [1,2,4]Triazolo[4,3‐a]pyridines

“…Unlike all previously obtained N-phosphanyl triazolium triflates [8], these compounds appeared to be surprisingly stable to moisture and air. In addition, they are also insoluble in water and after washing their crystals with water for purification from inorganic salts no traces of hydrolysis products were detected.…”

Di‐ and Trinuclear Gold Complexes of Diphenylphosphinoethyl‐Functionalised Imidazolium Salts and their N‐Heterocyclic Carbenes: Synthesis and Photophysical Properties

“…Although a few phosphine-substituted NHCs were published at the time we started this work, [13] none of those ligands were applied as a polydentate gold ligand. Meanwhile, a few macrocyclic cationic gold complexes, [39][40][41] as well as Cu, Ag, Ru, Ni, Pd and Pt compounds with N-phosphorylated or N-phosphinomethyl-substituted NHCs, were reported by Braunstein, Kostyuk and Hofmann (Scheme 1), [42][43][44][45] but to the best of our knowledge, neutral gold complexes with phosphorus-containing NHCs are still unknown. Herein, we present a full account of phosphinoethyl-tethered NHC ligands in gold(I) chemistry.…”

Synthesis and properties of heteroaromatic carbenes of the imidazole and triazole series and their fused analogues

“…297 The reaction of phosphanylated imidazoles and 1,2,4-triazol-5-ylidenes 62C to phosphanylazoles 62D proceeds similarly. 65,200,201 Thus, although in mainstream heterocyclic chemistry the N-substituent migration involves a carbene carbon atom, shifts to the 4 and 5 positions of the imidazol-2-ylidene nucleus are also possible.…”

“…Several carbenes, sterically shielded at positions 1 (tert-butyl, 1-adamantyl) and 4 (Mes, Dipp and lately Dbmp) 42D9-13, have been produced using this method, which confirms a wide range of possible uses for this synthetic scheme. 51,169 New phosphanylated 1,2,4-triazol-5-ylidenes 43A were synthesized by deprotonation of the respective triazolium sats, which, in turn, were obtained by quaternization of the corresponding triazoles with phosphanyl bromides or phosphanyltriazoles with alkyltriflates 200,201 . The above methods can be used to prepare a number of individual conjugated biscarbenes of the 1,2,4-triazole type (Х = p-С6Н4, m-С6Н4), as well as for the alіphatic bridged structures (compounds 43B, 43C) (Scheme 43).…”