Lucia Bonomo

PORPHOMETHENES AND PORPHODIMETHENES SYNTHESIZED BY THE TWO- AND FOUR-ELECTRON OXIDATION OF THE MESO-OCTAETHYLPORPHYRINOGEN

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.

Ruthenium Nitrides: Redox Chemistry and Photolability of the Ru–Nitrido Group

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.

Acetylenes Rearranging on Ruthenium–Porphyrinogen and Leading to Vinylidene and Carbene Functionalities

Through a proton-transfer reaction a porphyrinogen assists the transformation of terminal acetylenes into Ru-vinylidenes, which are the entry point to a variety of Ru-carbenes and Ru-cumulenes. The scheme (in which the porphyrinogen is stylized) shows the reversible interconversion of an acetylide into a divinylidene unit.

The π Complexation of Calcium inside themeso-Octaethylporphyrinogen Tetraanion Cavity

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 η3 -azaallyl binding sites for two calcium cations.

Ruthenium-Catalyzed Highly Chemoselective Hydrogenation of Aldehydes

The use of a [(ethylenediamine)(dppe)Ru(OCOtBu)2] [dppe=1,2‐bis(diphenylphosphino)ethane] complex under base‐free conditions allowed highly efficient and selective hydrogenation of aldehydes in the presence of ketones in addition to olefins. Even in the case of highly sensitive 1,6‐ketoaldehydes, the desired ketoalcohols were obtained in high yields with 94–99 % overall selectivity at complete aldehyde conversion with a TON up to 30 000. The lack of requirement for strong basic co‐catalysts and polar protic solvents also allowed efficient and highly chemoselective reduction of aldehydes bearing other functional groups, such as epoxides, carboxylic acids, esters, amides, and nitriles emphasizing the potential synthetic utility of the catalyst.

Unexpected Role of Anionic Ligands in the Ruthenium‐Catalyzed Base‐Free Selective Hydrogenation of Aldehydes

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.

A cylindrical cavity with two different hydrogen-binding boundaries: the calix[4]arene skeleton screwed onto the meso-positions of the calix[4]pyrrole†

The acid-catalyzed condensation of pyrrole with p- or m-hydroxyacetophenone led to the formation of meso-tetramethyltetrakis(hydroxyphenyl)calix[4]pyrroles occurring in three isomeric forms, with the cone conformer displaying topologically variable multi-site or multi-point surfaces for binding neutral or anionic substrates.

meso-Octaethylporphyrinogen Displaying Site Selectivity in the Stepwise Synthesis of Polymetallic Aggregates with Interesting Redox Properties: The π-Binding Ability of Metalla-Porphyrinogens

The sequential reaction of meso-octaethylporphyrinogen tetraanion with NiII followed by CoII, RuII, NiII allowed the build up of mixed coordination organometallic aggregates such as 1, which undergo thermally, chemically, or photochemically induced intramolecular electron transfers.

Synthese von Porphomethenen und Porphodimethenen durch Zwei- und Vier-Elektronen-Oxidation von meso-Octaethylporphyrinogen

Die stufenweise Desalkylierung von meso-Octaethylporphyrinogen 1 liefert Porphomethen 2 und Porphodimethen 3, wodurch grose Mengen dieser wertvollen Zwischenprodukte zuganglich werden. Die Synthesesequenz beruht auf der Reaktion mit SnCl4⋅2 THF, Li und H2O; das Ausmas der Desalkylierung hangt von der eingesetzten Menge an SnCl4⋅2 THF ab.

A Structural and Theoretical Analysis of Transition Metalloporphodimethenes and Their Relationship with Metalloporphyrins

The paper reports the synthesis of the first-row transition metal hexaethylporphodimethene derivatives [(Et6N4)M] [M=Mn, 3; M=Co, 5; M = Cu, 7] on a multigram scale, which makes them easily available for reactivity studies. After synthesis they were converted into the corresponding five-coordinate [(Et6,N4)M(L)] [M = Mn, L =THF, 8; M =Co, L = Py, 9] and six-coordinate [(Et6,N4)M(L)2] [M = Mn, L = THF, 10; M = Mn, L = Py, 11] derivatives. The compounds mentioned above and those recently reported, namely the iron and nickel derivatives 4, 6, 12, and 13, permit the presentation of the first coherent report on the structural, optical, magnetic, and electronic characteristics of the first-row transition metal porphodimethene derivatives. The experimental results, coupled with a detailed theoretical analysis (Density Functional Theory, DFT), give the appropriate background for future development of the porphodimethene skeleton, which paves the way from porphyrinogen to porphyrins. In addition, this report, encompassing the entire first row of transition metal ion porphodimethenes, allows a valuable comparison to be made with the corresponding metallated porphyrins, thus establishing the peculiar differences in terms of structural and electronic properties and potential reactivity.