Ru–Ag and Ru–Au dicarbene complexes from an abnormal carbene ruthenium system

Abstract

Reaction of [Ru(OAc)2(PPh3)2] with a P-functionalized imidazolium bromide easily affords a cationic abnormal carbene Ru system. Metalation with Ag2O yields a Ru-Ag complex containing an anionic dicarbene ligand, while subsequent transmetalation with Au(tht)Cl leads to the corresponding Ru-Au system. The bimetallic complexes were characterized by single crystal X-ray diffraction and are the first examples of complexes bearing anionic dicarbene ligands connecting two different d-block elements.

Tandem Suzuki–Miyaura/transfer hydrogenation reaction catalyzed by a Pd–Ru complex bearing an anionic dicarbene

“…The 1 H NMR spectrum of 3 in CD 2 -Cl 2 shows six different signals for the mesityl methyl groups and one signal for the acetate group. The 13 C{ 1 H} NMR of the normal Ru carbene appears as a doublet of doublets at d = 194.0 ppm with a 2 J CP = 101.0 and 11.2 Hz, due to the trans and cis P atoms; whereas the abnormal Ru carbene signal is at d = 150.7 ppm ( 2 J CP = 9.8 and 19.4 Hz), in agreement with the data of 1 and 2 [24]. The formation of the Pd normal carbene is confirmed by the doublet at 168.4 ppm, displaying a 3 J CP = 12.0 Hz.…”

“…The solvents used were purified, degassed, and dried according to standard purification techniques [49] or obtained from an MBraun solvent purification system. Complexes 1, 2 [24] and [PdCl 2 (IMes) 2 ] (IMes = 1,3-bis(mesityl)-imidazol-2-ylidene) [50] were obtained according to literature procedures. All further chemicals were purchased from commercial sources and used as received.…”

“…In particular, our groups described several NHC Ru catalysts for the transfer hydrogenation (TH) of ketones in 2-propanol [24][25][26]. Current advances in carbene chemistry focus on the development of unusual coordination geometries of the carbene ligand, and apart from abnormal carbenes [27,28], imidazolyl-derived anionic dicarbenes (N-heterocyclic dicarbenes, NHDCs) have recently attracted significant interest [24,[29][30][31][32].…”

“…In particular, our groups described several NHC Ru catalysts for the transfer hydrogenation (TH) of ketones in 2-propanol [24][25][26]. Current advances in carbene chemistry focus on the development of unusual coordination geometries of the carbene ligand, and apart from abnormal carbenes [27,28], imidazolyl-derived anionic dicarbenes (N-heterocyclic dicarbenes, NHDCs) have recently attracted significant interest [24,[29][30][31][32]. These compounds inherently allow the synthesis of bimetallic structures bearing two main-group elements [29,30,[32][33][34][35][36] or one main-group element and one transition metal [37][38][39][40][41], and examples featuring two transition metal centers are almost exclusively homobimetallic [42][43][44][45][46][47][48].…”

Phosphine‐NHC Manganese Hydrogenation Catalyst Exhibiting a Non‐Classical Metal‐Ligand Cooperative H2 Activation Mode

“…Compassing our recent investigations on the application of Mn I complexes supported by bidentate ligands in hydrogenation-type catalysis, [10] we turned our attention to the use of ligand systems now associating phosphine and NHC donors.C omplex 2 was readily obtained in 86 %y ield from the corresponding phosphine-imidazolium salt [1]OTs [11] through the sequential addition of KHMDS and [Mn-(CO) 5 Br] (Scheme 2). According to IR and NMR spectroscopy,t he air stable complex 2 forms as as ingle isomer (d P 71.3 ppm (s), d C 197.7 ppm (d, 2 J PC = 17.5 Hz, C N 2 C )), presenting af acial arrangement of the three carbonyl ligands as confirmed by an XRD study (Figure 1a).…”