Ruthenium(ii) carbonyl complexes bearing CCC-pincer bis-(carbene) ligands: synthesis, structures and activities toward recycle transfer hydrogenation reactions

Abstract

A new series of ruthenium(II) carbonyl complexes with benzene-based CCC-pincer bis-(carbene) ligands, [((R)CCC(R))Ru(CO)2(X)](0/+) and [((R)CCC(R))Ru(CO)(NN)](+) ((R)CCC(R) = 2,6-bis-(1-alkylimidazolylidene)benzene, R = Me or (n)Bu; X = I, Br, CH3CN, or 6-(aminomethyl)pyridine (ampy); NN = 2·CH3CN, or chelating ampy or bipyridine), was synthesized and fully characterized. X-Ray structure determinations revealed that these eight complexes have pseudo-octahedral configurations around the ruthenium center with the pincer ligand occupying three meridional sites. These complexes prove to be efficient precatalysts demonstrating very good activity and reusability for the transfer hydrogenation of ketones.

Synthesis of 2‐Ethyl‐19‐nor Analogs of 1α,25‐Dihydroxyvitamin D3

“…Transition metal complexes of the type [Rh III /Ir III ( R CCC R )] (R= n Bu, CH 2 SiMe 3 )24 bearing pincer ‐ bis‐NHC donors were previously obtained through a zirconium transmetallation procedure or by direct metallation in the presence of a base 25. Related ruthenium(II)26 or osmium(II)27 complexes featuring R CCC R pincer bisNHC ligands were also obtained in moderate to high yields via base‐promoted direct metallation. Alternatively, photoactive platinum(II) complexes featuring R CCC R (R=CH 2 SiMe 3 , or n Bu14b) pincer ligands constituting benzimidazol‐2‐ylidene17 or imidazol‐2‐ylidene14a donors were obtained through a zirconium transmetallation route.…”

Phosphatation of Zeolite H‐ZSM‐5: A Combined Microscopy and Spectroscopy Study

“…In the case of using a ruthenium(III) precursor such as RuCl 3 ⋅3 H 2 O, mostly ethylene glycol is used for its reducing properties and high boiling point. Using a solvent mixture of ethylene glycol/ethanol or only ethanol at elevated temperature results in the decarbonylation of ethanol and the in‐situ generated CO coordinates to the ruthenium ion 49. Ruthenium(II) sources such as [RuCl 2 (COD)] 2 and [RuCl 2 (PPh 3 ) 3 ] activate the CH bonds of both N‐heterocyclic carbenes and arene moieties in polar solvents like ethanol and 2‐propanol in the presence of TEA as a base to capture the liberated HCl.…”

Photofunctional Platinum Complexes Featuring N‐heterocyclic Carbene‐Based Pincer Ligands

“…[24] bearing pincer-bis-NHC donors were previously obtained through a zirconium transmetallation procedure or by direct metallation in the presence of a base. [25] Related ruthenium(II) [26] or osmium(II) [27] complexes featuring R CCC R pincer bisNHC ligands were also obtained in moderate to high yields via base-promoted direct metallation. Alternatively, photoactive platinum(II) complexes featuring R CCC R (R = CH 2 SiMe 3 , or nBu [14b] ) pincer ligands constituting benzimidazol-2-ylidene [17] or imidazol-2-ylidene [14a] donors were obtained through a zirconium transmetallation route.…”