Phosphorus or nitrogen - the first phosphatriptycene in coordination polymer chemistry.

Abstract

Phosphasilatriptycene, a phenylene spacer and a pyridyl moiety represent the building blocks of TRIP-Py, the first heteroditopic ligand featuring a phoshatriptycene scaffold. The P and N donor sites located at opposite ends of the prolate TRIP-Py molecule selectively coordinate metal cations matching their Pearson character. The harder pyridyl donor binds to ZnII, the softer phosphorus donor to PtII, HgII and AuI. The remarkably short Au-P bond in the latter underlines the good π acceptor character of the phoshatriptycene moiety. When both the chloride salts of hard ZnII and soft AuI cations are available for coordination, TRIP-Py acts as selective ditopic linker in the discrete trinuclear mixed-metal complex [ZnCl2(TRIP-PyAuCl)2]. For CdII, a cation with intermediate Pearson character, selectivity withers, and a monometallic coordination polymer is obtained. Its significantly elongated Cd-P coordinative bonds underline, however, the preference of CdII for the harder N donor. When ZnII and HgII halides are combined, their preference for the matching donor sites in TRIP-Py and for tetrahedral coordination afford 1D and 2D heterobimetallic polymers with and without solvent-accessible voids. TRIP-Py enables the use of two important analytical tools: its rigidity facilitates crystallization and allowed to investigate 14 crystalline solids, and its P donor provides a powerful NMR probe for coordination.