Single‐Step Orientational Self‐Assembly of Pd Metallacycles and Heterometallic Pd–Pt Helical Cages From Heteroditopic Ligands

ABSTRACT Controlling the self‐assembly of heterometallic supramolecular architectures without generating statistical mixtures remains a major challenge. Here, we show that adaptable coordination modes of tetrazole units in heterodipotic tetrazole–pyridine ligands direct both orientational self‐sorting and selective metal organization. Reaction with cis‐protected Pd(II) acceptors afforded Pd 6 ( L ) 4 metallacycles ( L = L1 – L3 ), in which tetrazolate coordination through an unusual (2,3) binding mode is exploited in the orientational self‐sorting. In contrast, ligand L4 employed its (1,3) coordination mode together with the pyridyl donors to generate a Pd 9 ( L4 ) 6 helical cage and the heterometallic Pd 9 Ag( L4 ) 6 , and Pd 3 Pt 6 ( L4 ) 6 cages in single‐step self‐assembly processes. Remarkably, despite the closely matched coordination preferences of Pd(II) and Pt(II), the synergistic effects of donor inequivalence and the flexible coordination behavior selectively partitions the two congeneric d 8 ions into distinct coordination sites within the Pd 3 Pt 6 ( L4 ) 6 cage. The uncommon (1,2,3) tetrazolate binding mode additionally enables formation of the Pd 9 Ag( L4 ) 6 cage. Encapsulation of enantiopure guests by the helical cages induces host chirality and corresponding chiroptical responses. These results demonstrate that coordination mode flexibility of the tetrazole moiety combined with the pyridyl unit can direct the formation of metallacycles and helical cages and enable selective partitioning of closely related metal ions in a single‐step assembly.