Evaluation of Planar‐ and Bowl‐Shaped Metallophosphaporphyrins. Inclusion of Steric Effects in P4‐Metalloporphyrins Counterparts

ABSTRACT Corannulene, C 20 H 10 , experience a bowl‐to‐bowl inversion through planar conformation. The replacement of the N4‐kernel in metalloporphyrins (MN4) to P4, leading to metallophosphaporphyrins (MP4), introduces steric effects resulting a bowl‐like MP4 counterpart. Here, we explore the driving terms in determining the bowl‐shape in the first transition metal series from Sc to Zn (MP4), by using Density Functional Theory (DFT) methods, and the related variation of the particular π ‐hole and UV–vis characteristics in relation to parent metalloporphyrins. Our results reveal that the variation of flat to bowl structure for the MP4 series for the Sc─Mn metals, is driven mainly by the release in the Pauli repulsion, whereas for the Fe─Zn, is provided by the main contribution from the electrostatic stabilization achieved in the bowl‐like MP4 structure. Particularly for NiP4 and CoP4, a bowl‐to‐bowl inversion is expected to be favorable. The π ‐hole capabilities are largely enhanced in the bowl MP4 structure for Sc, Ti, V, Cr, and Mn, in comparison to their MP4 parents. In contrast, for the related CoP4, NiP4, CuP4, and ZnP4, species denote a more electron‐rich π ‐hole site. These observations denote that the use of a more sterically demanding P4‐coordination site serves as a plausible design strategy to expand the characteristics of metalloporphyrins.