Coordination Chemistry of a Modular N,C-Chelating Oxazole-Carbene Ligand and Its Applications in Hydrosilylation Catalysis

Abstract

Reaction of 1-mesitylimidazole with 2-chlorobenzoxazole gave the 2-benzoxazolyl imidazolium salt bzoxcarbH + Cl -(1), which was converted to the silver N-heterocyclic carbene complex [Ag I (bzoxcarb)-Cl] (2) by reaction with Ag 2 O in dichloromethane. The crystal structure analysis confirmed the monomeric nature of complex 2. The silver complex 2 was reacted with [PdCl 2 (COD)] to yield the corresponding palladium complex [PdCl 2 (bzoxcarb)] (3), for which an X-ray diffraction study established a distorted square planar configuration with the imidazolyl and the oxazolyl ring lying within the molecular plane. Upon direct reaction of the imidazolium salt 1 with Pd(OAc) 2 /NaI, a bis-carbene palladium complex [PdI 2 (bzoxcarb) 2 ] (4) was obtained. The rhodium complex [RhCl(bzoxcarb)(CO)] ( 5) was prepared in high yield in a one-step reaction of 1 with [Rh(acac)(CO) 2 ] (acac ) acetylacetonate). The silver N-heterocyclic carbene complex 2 was also used as carbene transfer reagent in the synthesis of the platinum complex [PtCl 2 (bzoxcarb)] ( 6), which was found to be an active catalyst for the hydrosilylation of alkenes and alkynes.

A New Class of Modular Oxazoline‐NHC Ligands and Their Coordination Chemistry with Platinum Metals

“…[31] Complex 7 derived from imidazolium salt 2e has spectroscopic data which are very similar to those of its bromo analogue and was fully characterized by X-ray diffraction. Its molecular structure is represented in Figure 6 along with the main bond lengths and angles.…”

Recent Progress in the Complexes Functionalized N, C Bidentate N-Heterocyclic Carbenes

“…Poyatos 等合成了携带苯 并唑基团的双齿 NHC 的钯、铂、铑配合物 80a, 80b, 81 [33] , 其中配合物 80b 在烯烃和炔烃的氢硅化反应中显 示了催化活性( Scheme 20). …”

Catalisadores contendo carbenos n-heterocíclicos como ligantes: propriedades, sínteses, aplicações e comparação com outros ligantes

“…Vários anos depois, esta ainda é uma das principais rotas empregadas na síntese de complexos de paládio(II) e níquel(II), a partir dos correspondentes acetatos ou cloretos em presença de sais azólicos (Esquema 11a). 40 Em complexos de ródio ou irídio, ligantes do tipo oxo na estrutura do precursor cumprem o papel do ânion, atuando como bases. .…”