Stepwise dealkylation of meso‐octaethylporphyrinogen 1 yields porphomethene 2 and porphodimethene 3, providing access to large quantities of these valuable intermediates. The synthetic sequence relies on SnCl4⋅2 THF, Li, and H2O; the extent of dealkylation depends on the amount of SnCl4⋅2 THF employed.

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A possible binding cavity for alkali and alkaline earth metal ions: The synthesis and structural characterization of the complex shown, which was obtained from meso-octaethylporphyrinogen and calcium metal, shows that the porphyrinogen functions as a binucleating ligand with four η -azaallyl binding sites for two calcium cations.

Bigger and better: The replacement of anionic chloride ligands in Noyori-type [(diamine)(diphosphine)RuCl2 ] catalysts with bulky carboxylate ligands enabled the efficient selective hydrogenation of a variety of aldehydes under base-free conditions. Turnover numbers of up to 100 000 were reached in the presence of a bulky carboxylic acid co-catalyst. This type of catalytic system probably operates through an inner-sphere mechanism.

Tunable electrophilicity/nucleophilicity by means of the redox properties of the Ru≡N group and reversible interconversion of mononuclear and dinuclear species as a result of the photolability of the Ru=N=Ru group are characteristic of the nitrido derivatives of Ru porphyrinogens. For example, 2, the product of reversible reduction of a Ru≡N precusor, reacts with 1 in the dark to form 3, which undergoes photocleavage to 1 and 2.