1416171-26-0Relevant articles and documents
Homo-and heterobimetallic Pd-, Ag-, and Ni-hybrid salen-bis-NHC complexes
Mechler, Melanie,Latendorf, Katja,Frey, Wolfgang,Peters, Rene
, p. 112 - 130 (2013/02/25)
salen ligands and N-heterocyclic carbenes (NHC) are among the most abundant structural ligand motifs for metal catalysis. In this article we present a modular approach to chiral ligands merging both ligand motifs for the preparation of bimetallic catalysts, in which one metal (M1) is coordinated by the salen moiety and the other metal (M2) binds to two NHCs. After selective complexation of M1 = PdII, Ni II ion into the salen N2O2 coordination site, heterobimetallic M1/Ag(I) complexes were synthesized which could be further utilized for the preparation of homo-and heterobimetallic M 1/PdII complexes by an oxidative transmetalation to Pd(0) as a key step of the catalyst synthesis. The structures of the bimetallic complexes and the intermetallic distances strongly depend on the counterions of M2 = PdII, as revealed by X-ray and UV-vis studies. In the absence of an anionic ligand with suitable Lewis basicity the salen oxygen atoms serve as bridging ligands for both metals. A preliminary investigation into catalysis showed that the complexes are capable of catalyzing the 1,4-addition of oxindoles to 2-nitrostyrene.
