Zirconium Metal-Organic Frameworks Assembled from Pd and Pt PNP Pincer Complexes: Synthesis, Postsynthetic Modification, and Lewis Acid Catalysis.

Carboxylic acid-functionalized Pd and Pt PNP pincer complexes were used for the assembly of two porous Zr metal-organic frameworks (MOFs), 2-PdX and 2-PtX. Powder X-ray diffraction analysis shows that the new MOFs adopt cubic framework structures similar to the previously reported ZrO(OH)[(PCP)PdX], [PCP = 2,6-(OPAr)CH); Ar = p-CHCO, X = Cl, I] (1-PdX). Elemental analysis and spectroscopic characterization indicate the presence of missing linker defects, and 2-PdX and 2-PtX were formulated as ZrO(OH)(OAc)[M(PNP)X] [M = Pd, Pt; PNP = 2,6-(HNPAr)CHN; Ar = p-CHCO; X = Cl, I]. Postsynthetic halide ligand exchange reactions were carried out by treating 2-PdX with Ag(OSCF) or NaI followed by PhI(OCCF). The latter strategy proved to be more effective at activating the MOF for the catalytic intramolecular hydroamination of an o-substituted alkynyl aniline, underscoring the advantage of using halide exchange reagents that produce soluble byproducts.