Construction of heterometallic M2Pd3 supramolecular cages via a metalloligand strategy as heterogeneous catalyst for Suzuki–Miyaura coupling reaction

• Published in: Inorganica Chimica Acta 2018-10, Vol.482, p.605-611
• Main Authors: Wu, Xi-Ren, Yao, Su-Yang, Wei, Lian-Qiang, Li, Li-Ping, Ye, Bao-Hui
• Format: Article
• Language: English
• Subjects: Heterogeneous catalyst; Metalloligand; Palladium complexes; Supramolecular cages; Suzuki-Miyaura coupling
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2018.07.009

Neutral heterometallic M2Pd3 supramolecular cages with a trigonal bipyramid geometry have been successfully assembled via the metalloligand strategy on the basis of HSAB theory and exhibit high catalytic activity for the Suzuki–Miyaura coupling reaction in a biorenewable solvent under mild conditions. [Display omitted] •Developed heterogeneous single-site M2Pd3 catalyst to prolong catalyst lifetime.•Highly efficient and recyclable supramolecular catalyst for Suzuki–Miyaura reaction.•Both aryl bromine and aryl chloride were suitable substrates.•Mild reaction conditions and environment-friendly. On the basis of hard soft acid base theory, two neutral heterometallic M2Pd3 supramolecular cages, [Al2Pd3(L)6Cl6] (1) and [Fe2Pd3(L)6Cl6] (2) (where HL is 1-(4-(1H-imidazol-1-yl)phenyl)butane-1,3-dione), have been constructed by using the tripodal M(L)3 as metalloligands in combination with PdCl2 or Pd(MeCN)2Cl2. The supramolecular cage can be described as a trigonal bipyramid with two M3+ ions occupying at the two axial sites in ΔΔ or ΛΛ configurations and three Pd2+ ions sitting in the three equatorial positions with square planar geometry in trans configuration. The supramolecular cages exhibit high catalytic activity for the Suzuki–Miyaura coupling with arylbromide or arylchrolide and phenylboronic acid in biorenewable solvent glycerol under mild conditions. Moreover, the catalyst can be readily recycled and reused at least five times without loss of catalytic activity. The high catalytic performance may be attributed to the distinct properties of the cage structure with uniformly distributive and well-defined Pd active centres on the cage surfaces. The high stability in the cage structure also prevents Pd leaching out and agglomeration.