Complexes of N-Confused Porphyrin Derivatives as Ortho-Metallating Ligands. Synthesis, Structure, Redox Properties, and Chirality.

A family of transition metal complexes of meso-aryl-2-aza-21-carbaporphyrin (N-confused porphyrin, NCP) derivatives acting as ortho-metallating ligands for ruthenium(II), rhodium(III), and iridium(III) is synthesized and characterized by XRD, spectroscopic, and electrochemical methods. The chirality of these systems is shown by the separation of the enantiomers and analyzed by circular dichroism and DFT. A preliminary catalytic study indicates the activity of the iridium(III) ortho-metallated complexes in the N-heterocyclization of primary amines with diols.

Oxidative insertion of amines into conjugated macrocycles: transformation of antiaromatic norcorrole into aromatic azacorrole.

A new group of aromatic porphyrinoids was obtained by an oxidative insertion of primary amines into the antiaromatic ring of 5,14-dimesityl-norcorrolatonickel(II) activated by iodosobenzene. The substituted 10-azacorroles thus formed were characterized by spectroscopic and electrochemical methods, and XRD analysis. Protonated forms of azacorroles were shown to remain aromatic despite disconnection of the original π-electron delocalization path.

Two Rhodium(III) Ions Confined in a [18]Porphyrin Frame: 5,10,15,20-Tetraaryl-21,23-dirhodaporphyrin.

Invited for the cover of this issue is the group of Ewa Pacholska-Dudziak at the University of Wroclaw. The image depicts two rhodium atoms being fixed into the skeleton of 21,23-dirhodaporphyrin in place of two core nitrogen donors. Read the full text of the article at 10.1002/chem.202201513.

Two Rhodium(III) Ions Confined in a [18]Porphyrin Frame: 5,10,15,20-Tetraaryl-21,23-Dirhodaporphyrin.

Tetraaryl-21,23-dirhodaporphyrin and a series of related monorhodaporphyrins have been obtained by tellurium-to-rhodium exchange in a reaction of tetraaryl-21,23-ditelluraporphyrin with [RhCl(CO)2 ]2 . These organometallic metallaporphyrins contain rhodium(III) centers embedded in rhodacyclopentadiene rings, incorporated within the porphyrin frames. The skeletons of 21,23-dirhodaporphyrin and 21-rhoda-23-telluraporphyrin are strongly deformed in-plane from the rectangular shape typical for porphyrins, due to rhodium(III) coordination preferences, the large size of the two core atoms, and the porphyrin skeleton constrains. These two metallaporphyrins exhibit fluxional behavior, as studied by 1 H NMR and DFT, involving the in-plane motion and the switch of the rhodium center(s) between two nitrogen donors. A side product detected in the reaction mixture, 21-oxa-23-rhodaporphyrin, results from tellurium-to-oxygen exchange, occurring in parallel to the tellurium-to-rhodium exchange. The reaction paths and mechanisms have been analyzed. The title 21,23-dirhodaporphyrin contains a bridged bimetallic unit, Rh2 Cl2 , in the center of the macrocycle, with two rhodium(III) ions lying approximately in the plane of the porphyrinoid skeleton. The geometry of the implanted Rh2 Cl2 unit is affected by macrocyclic constrains.

1,3-Dipolar cycloaddition of polycyclic azomethine ylide to norcorroles: towards dibenzoullazine-fused derivatives.

A 1,3-cycloaddition reaction of 2-(tert-butyl)-8H-isoquinolino[4,3,2-de]phenanthridin-9-ium chloride to NiII norcorrole in the presence of base is shown to produce a family of chiral derivatives of polycyclic system(s) fused with pyrrole subunit(s) of the macrocycle. Dehydrogenation of the cycloaddition products gave rise to dibenzoullazine ortho-fused antiaromatic porphyrinoids.

From Antiaromatic Norcorrolatonickel(II) to Aromatic and Nonaromatic Zwitterions: Innocent Ligands with Unbalanced Charge of the Core.

A three-component reaction of antiaromatic meso-mesityl-3-nitronorcorrolatonickel(II) 1-NO2 with dialkyl acetylenedicarboxylate and PBu3 yields aromatic zwitterionic corrole nickel(II) complexes 3-R with one of the meso-substituents comprising a positively charged tributyl phosphonium group and negatively charged coordination core. Reaction of 1-NO2 with PBu3 alone resulted in a nonaromatic chiral adduct 5 of a zwitterionic phlorine character with a -PBu3+ group at a pyrrole ß-position.

First imidazole-fused carbaporphyrinoid and its conversion to a N-heterocyclic carbene precursor.

A series of novel imidazole-fused carbaporphyrinoids were obtained by a surprisingly simple approach by exploiting the reaction of tosylmethylisocyanide (TOSMIC) with readily obtainable 2-aza-21-carbaporphyrins. A facile methylation of silver(iii) complexes of these fused systems leads to cationic N-heterocyclic carbene precursors.