Triptycenes, bicyclic molecules featuring a rigid paddlewheelshaped skeleton, were first prepared in the early 1940s, and have since found extensive applications as key structural elements in materials chemistry, catalysis, 3 and supramolecular systems, including sensors and molecular machines. Replacing the apical methyne group in these molecules with boron, nitrogen or phosphorus atoms results in the corresponding aza-, bora-, and phosphatriptycene derivatives, which have also been prepared, though they remain much less explored (Scheme 1a). Within this series, only the triptycene and the phosphatriptycene were shown to engage their apical atom in a coordinative bonding of transition metals. Specifically, chelation-assisted activation of the bridgehead Csp 3 -H bond in triptycene-based PCP pincer ligands, first prepared and extensively studied by Gelman, resulted in highly thermally robust complexes (Scheme 1b). Among these, Ir(III)-triptycene complexes exhibited an excellent catalytic performance in transfer hydrogenation of ketones and transfer dehydrogenation of alkanes, as demonstrated by Gelman 9a and Brookhart. Phosphatriptycenes, on the other hand, have seen little use as ligands in homogeneous catalysis, despite being known for 50 years. 7a Due to a significant ring strain imposed by their bicyclic scaffold, the apical P atom in these compounds is highly pyramidalized, which increases the s character of its lone pair. Consequently, phosphatriptycenes are somewhat weaker electron donors compared to the non-cyclic phosphines, although assessment of their Tollman electronic parameter in a Rh(acac)CO system (Scheme 1c) suggested only a small difference (7 cm -1 at most). Indeed, when a phosphatriptycene ligand was employed in Pd-catalyzed reactions benefitting from an electronpoor metal center, it offered only a modest improvement over other week donors, such as trifurylphosphine and triphenylarsine. 12 Scheme 1. General structure of a triptycene molecule and its heteroatom-based analogues (a), transition metal complexes of triptycene (b) and phosphatriptycene (c), the only previously reported thiatriptycenium cation (d), and a zwitterionic 9-sulfonium-10-boratriptycene (e).