Palladium(ii)- and platinum(ii)phenyl-2,6-bis(oxazole) pincer complexes: Syntheses, crystal structures, and photophysical properties

Abstract

Phenyl-2,6-bis(oxazole) ligands have been explored for the synthesis of novel palladium(II) and platinum(II) pincer complexes. The materials were characterized by spectroscopic methods and by X-ray crystallography. Investigations of the photophysical properties revealed that the lowest triplet states of the materials are largely centred at the bis(oxazole) ligands. The platinum(II) compounds are moderately emissive in fluid solution at ambient temperature. Introduction of both strong donors and strong acceptors leads to a significant red shift of the emission. Due to the facile synthesis of bis(oxazole) based complexes with electronically tuneable oxazole moieties, these materials might be promising alternatives to the well-established phenyl-2,6-bipyridyl systems.

An Efficient Protocol for the Amidation of Carboxylic Acids Promoted by Trimethyl Phosphite and Iodine

“…The good chemoselectivity of this method was deductively attributed to the fact that the relatively low reactivity of the mixed anhydride allowed discrimination between the subtly different nucleophilicities of the nucleophiles. In other words, for highly activated carboxyl forms, for example, acyl halides, the selectivity tends to be low 25. These observations implied that our protocol had the remarkable advantage that it can be used to exclusively select nitrogen nucleophiles against sulfur and oxygen nucleophiles.…”

“…To elucidate the chemoselectivity of this method, several competitive experiments were conducted (Scheme 25). When a mixture of aniline and methanol (1:10) was used in this procedure [Scheme , Equation (1)], the amine was predominantly acylated in 94 % yield, and no ester wasobtained.…”

Palladium complexes containing imino phenoxide ligands: synthesis, luminescence, and their use as catalysts for the ring-opening polymerization of rac-lactide

“…Besides ubiquitous applications in catalysis for coupling reactions, palladium complexes were intensively investigated due to their interesting luminescence properties [ 13 , 14 ]. However, only limited number of papers has been published investigating emissive properties using salen-type or imino phenoxide ligands [ 15 ].…”

[2,6-Bis(5-ethoxy-1,3-oxazol-2-yl)-4-methoxyphenyl-κ3N,C1,N′]bromidopalladium(II)

“…For palladium complexes with NCN pincer ligands, see: Hao et al (2010); Young et al (2011). For studies on the chemistry of bis(oxazole) pincer palladium complexes, see: Luo et al (2007Luo et al ( , 2011; Xu et al (2011). For structures of related bis(azole) pincer palladium complexes, see: Ghorai et al (2012); Luo et al (2012).…”

“…Considerable attention has recently been devoted to pincer-Pd complexes due to their catalytic abilities (Ghorai et al, 2012;van Koten & Gebbink, 2011;Moreno et al, 2010;Selander & Szabó, 2011). We are interested in the NCN type of pincer-Pd complexes (Luo et al, 2007(Luo et al, , 2011(Luo et al, , 2012Xu et al, 2011) as a variety of nonphosphine pincer catalytic system, that contains two nitrogen atoms as donating sites in the coordination sphere (Hao et al, 2010;Young et al, 2011) The title compound was conveniently synthesized from the reaction of Pd(dba) 2 (dba = dibenzylideneacetone) with 1bromo-2,6-bis(5-ethoxyoxazol-2-yl)-4-methoxy benzene in dry benzene under reflux in an argon atmosphere. As a result, the title compound was isolated with 84% yield.…”