A Weak Donor, Planar Chelating Bitriazole N-Heterocyclic Carbene Ligand for Ruthenium(II), Palladium(II), and Rhodium

Abstract

The new ligand bitriazole-2-ylidene (bitz) has been successfully coordinated to Ru(II), Pd(II), Rh(I), Rh(II), and Rh(III), showing its wide chemical versatility. Reaction of the bitz ligand precursor salt, 1,1′-methyl-4,4′-bi-1,2,4-triazolium diiodide, with [RhCl(cod)]2 under mild conditions afforded chelate and bis-chelate Rh(III) complexes, as well as an unexpected metal−metal bounded di-Rh(II) species. The reaction of the precursor salt of bitz with [(η6-p-cymene)RuCl2]2 and NaOAc afforded a mixture of chelate and dimetallic Ru(II)-arene complexes. The reaction of the salt with Pd(OAc)2 led to a chelate complex. In an unexpected, purely organic reaction, the precursor salt rearranges to a new C−C bound bitriazole on reaction with strong base in the absence of the metal. The electron-donor power of the bitz ligand, estimated by DFT computations, proved to be very low for an NHC and comparable with those of dmpe and dipy. Some of the new complexes proved to be catalytically active in hydrogen transfer from iPrOH.

Study of complexes of platinum group metals containing nitrogen bases derived from pyridine aldehydes: Interesting molecular structures with unpredicted bonding modes of the ligands

“…In this dinuclear complex, at 2.4545(13) and 2.4489(12) Å, the Ru-Cl distances are comparable to those found in other chloro-bridged complexes involving ruthenium centers [34,35]. Similarly, the metalemetal distance [4.0679(6) Å] lies in the typical range for single chlorobridged dinuclear arene ruthenium complexes [36,37].…”

Quinobis(imidazolylidene): Synthesis and Study of an Electron‐Configurable Bis(N‐Heterocyclic Carbene) and Its Bimetallic Complexes

“…Organometallic systems bearing N-heterocyclic carbene (NHC) ligands are useful catalysts for functional-group transformations and polymerization reactions, [3][4][5][6][7][8][9][10][11][12][13] and complexes featuring multitopic NHCs have recently emerged [14] as promising candidates for asymmetric and tandem catalysis, [15][16][17] as well as other applications. [18,19] Variants featuring two NHC moieties linked by a p-conjugated system, such as benzobis(imidazolylidene) (BBI), [20,21] triazolyldiylidene (A), [22] bitriazolylidene (B), [23] pyridylbis-A C H T U N G T R E N N U N G (imidazolylidene) (C), [24][25][26] and pyridazinylbis(imidazolyl-A C H T U N G T R E N N U N G idene) (D) [27,28] have found numerous uses as ditopic ligands (Scheme 1). For example, BBIs have yielded phosphorescent complexes, [29] polymeric catalysts, [30] emissive and conducting polymers, [21,[31][32][33] and self-assembled materials.…”

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

“…Perіs et al 207,208 proposed using bіstriazolylіdene lіgands for the synthesis of precursors to 43C, prior to the generation of metal complexes. However, carbenes of this type have not yet been prepared.…”