Chiral platinum and palladium complexes containing functionalized C2-symmetric bisaminoaryl ‘Pincer’ ligands

Abstract

Dedicated to Professor Jean Normant on the occasion of his 65th anniversary in admiration of his great contribution to the application of organocopper chemistry. AbstractThe synthesis of enantiopure (oxo-functionalized) C 2 -symmetric NCN pincer ligands is described. A key step is the symmetric functionalization of the benzylic positions, which was achieved by enantioselective ketone reduction and subsequent stereoselective substitution protocols. The introduction of a-alkyl substituents has a pronounced effect on the cavity for metal binding. For example, lithiation of the a-ethyl-functionalized pincer ligand afforded mixed (alkyl)(aryl)lithium aggregates rather than dinuclear bis(aryl) lithium [Li(NCN)] 2 species as usually observed for NCN-lithium complexes. Similar effects were established for the (trans)-metalation reaction, which proceeded significantly slower when the steric demand of the a-substituent is increased. The potential of the corresponding enantiopure palladium and ruthenium complexes as enantioselective catalyst has been probed in the asymmetric aldol condensation and hydrogen transfer reactions. The low enantiomeric excess of the products of both reactions indicated that face-discrimination of substrates is not induced by these catalysts and that the chiral information must be located in closer proximity to the metal center.

Luminescent and Electronic Properties of Stilbenoid NCN‐Pincer PtII Compounds

“…13.64 (12) [21,[46][47][48][49] shows a similar distorted square-planar geometry around the Pt nucleus in which the carbon atoms of the benzylic substituents (C7 and C10) are positioned above and below the plane defined by C1-N1-Pt1-N2-Cl1. For the two five-membered metallacycles, which are slightly puckered, torsion angles for the Pt1-N1-C7-C2 and Pt1-N2-C10-C6 bonds ranging from 25 to 32°were found.…”

Cyclometalation Using d-Block Transition Metals: Fundamental Aspects and Recent Trends

“…23 Cyclometalations that are assisted by oxygen, arsenic, and selenium donors are also known, though they are much rarer. 149,150 Chirality has been incorporated, for example through asymmetric ligand synthesis, [426][427][428][429][430] 436 Monomers are also present in solvents like benzene at high temperatures.…”

Solid-state and solution structures of hetero-aggregates formed between nBuLi and NCN pincer aryl lithium

“…[60][61][62][63][64] Recently, the reactivity and stereoselective self-assembly of the homo and hetero-aggregates of chiral and achiral bidentate 2-[(dialkylamino)methyl]aryl-1-lithium species 2, containing an NC donor set, have also been reported.…”