Phosphorus or nitrogen - the first phosphatriptycene in coordination polymer chemistry

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 Zn^II, the softer phosphorus donor to Pt^II, Hg^II and Au^I. 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 Zn^II and soft Au^I cations are available for coordination, TRIP-Py acts as selective ditopic linker in the discrete trinuclear mixed-metal complex [ZnCl₂(TRIP-PyAuCl)₂]. For Cd^II, 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 Cd^II for the harder N donor. When Zn^II and Hg^II 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.