Unveiling reactive metal sites in a Pd pincer MOF: insights into Lewis acid and pore selective catalysis

Abstract

A porous Zr metal–organic framework, 1-PdBF₄ [Zr₆O₄(OH)₄(OAc)_2.4{(P^NN^NP)Pd(MeCN)}_2.4(BF₄)_2.4; P^NN^NP = 2,6-(HNPAr₂)₂C₅H₃N; Ar = p-C₆H₄CO₂⁻], has been synthesized via postsynthetic oxidative I⁻/BF₄⁻ ligand exchange using NOBF₄. 1-PdBF₄ enjoys markedly superior catalytic activity and recyclability to its trifluoracetate-exchanged analogue, 1-PdTFA, for the intramolecular cyclization of o-alkynyl anilines and the carbonyl–ene cyclization of citronellal. Moreover, 1-PdBF₄ demonstrates a rare example of pore selective catalysis for the cyclization of 2-ethynyl aniline.