Coordination Chemistry of the PdmBOX Pincer Ligand: Reactivity at the Metal and the Ligand

Abstract

Abstract:The coordination chemistry of PdmBOX [2,5-bis(2-oxazolinyldimethylmethyl) (5)

Catalyzing the Hydrodefluorination of CF3-Substituted Alkenes by PhSiH3. H• Transfer from a Nickel Hydride

“…The Ni(I) can abstract halides from organic compounds and make Ni(II) halides, from which Ni(II)-H can be regenerated with silanes and boron hydrides. [49][50][51][52] While investigating hydrogen atom transfer (HAT) from 1a, we found that it carried out the hydrodefluorination of α-CF 3 styrene 2a (Scheme 2). During that reaction, the characteristic 19 F NMR resonance of the Ni(II)-F complex 1b was observed at δ −444.3.…”

Manganese‐Catalyzed Hydrosilylation Reactions

“…A wide range of chiral secondary alcohols 44 were obtained in good to excellent yields and enantioselectivities after hydrolysis of the hydrosilylation products. Later on, the Gade group developed manganese complexes bearing pincer ligands 45 and 46 , which showed a moderate enantioselectivity in the reduction of acetophenone (Scheme b) …”

“…Aw ide range of chiral secondary alcohols 44 were obtained in good to excellent yields and enantioselectivities after hydrolysiso ft he hydrosilylation products.L ater on, the Gade group developedm anganese complexes bearingp incer ligands 45 and 46,w hich showed am oderate enantioselectivity in the reduction of acetophenone (Scheme 9b). [23] So far,o nly af ew examples of manganese-catalyzed amide reduction withs ilanes have been reported. With the co-existence of [Mn 2 (CO) 10 ]a nd Et 2 NH, N-acetylpiperidine (47)w as readily reducedt oN-ethylpiperidine (48;S cheme 10a).…”

“…In the 1990s, manganese carbonyl acyl catalysts were widely utilized in the works reported by the group of Cutler, and exhibited high reactivities in the hydrosilylationo f ketones, [14] esters, [15] and organoiron complexes. [11][12][13] In addition, many manganese catalysts covered in this review,i ncluding carbonyl-Mn complexes, half-sandwich manganese complexes, [16,18] Salen-Mn complexes, [17] bis-NHC-Mn complexes, [20] pincerm anganese complexes, [21][22][23] as well as manganeseamide complexes, [26] also presented their features on carbonyl hydrosilylation reactions. Of particular note is that the catalytic system reported by Trovitchh ad the highest TOF (4950 min À1 ) among all the base-metal catalysts, [21d] which might provide potentialf or large-scale applications of manganese catalysts in the hydrosilylation industry.…”

Backbone Dehydrogenation in Pyrrole-Based Pincer Ligands

“…12–16 Notable examples featuring anionic pincers include the amide-based NNN/ONO ligands studied by Heyduk, 17–21 the asymmetric diamine-amido PN 3 P ligands developed by Huang, 22,23 the pyrrolide-oxazoline NNN ligands introduced by Gade, 2,24 the diiminopyrrole-derived NNN ligands recently prepared by Anderson, 25,26 and the aliphatic amine-based PNP ligands employed by Schneider. 27 In the latter case, removal of H 2 equivalents from the pincer backbone afforded modified ligands with higher degrees of unsaturation.…”