Incorporation of a p‐Phenylene Unit into the Azuliporphyrinogens Frame—Oxidation and Ruthenium Cluster Coordination

Abstract

A porphyrinogen macrocycle incorporating two azulenes, phenylene and thiophene into the framework, joined by four C(sp ) atoms has been obtained as a mixture of six isomers. They were successfully separated and characterized spectroscopically. The identity of two of them was confirmed by X-ray crystallography. One isomer was tested in reaction with [Ru (CO) ] yielding exclusively π-complex with two clusters attached to azulenes. The partial oxidation of porphyrinogens yielded dication with two unmodified meso bridges. The stepwise oxidation followed by reaction with water as nucleophile afforded the dicationic species with two hydroxyl groups and a trication with one OH group. The hydroxy-dication can be reversibly transformed into hydroxy-trication by addition of HBF etherate.

C−H and C−M Activation, Aromaticity Tuning, and Co⋅⋅⋅Ru Interactions Confined in the Azuliporphyrin Framework

“…Similar coordination shifts were previously detected for a Ru 4 (CO) 9 cluster π‐bound to azuliporphyrin σ‐complexes and azuliporphyrinogens . Coupling constants for azulene protons of 1‐Co(CO) also decreased from about 10 Hz, typical for azulene derivatives, to 7–9 Hz, as expected for π‐coordinated azulene.…”

“…The 2‐CoRu molecule acquires a structure that merges two coordination modes: a μ‐oxo complex and azulene π‐coordinated to a cluster (Figure ). Evidently, the bonding of Ru 4 (CO) 9 deforms the azulene frame, adjusting to a cluster geometry closely resembling the structural arrangements previously reported for azuliporphyrin, azuliporphyrinogens, and azulene environments . The structural parameters reflect the low‐spin character of the center; in particular, the relatively short Co−O21 (1.935(5) Å) and C−N bond lengths (Co−N22 1.926(7); Co−N23 1.895(6); Co−N24 1.919(7) Å) compared with the (2‐Co) 2 ones (Figure ).…”

“…The azulene moiety of 1‐Co was expected to serve as a π‐coordination platform suitable to accommodate a Ru 4 (CO) 9 cluster following the chemistry that gave rise to a series of bimetallic diamagnetic complexes metal(II) azuliporphyrin [M( 1 )(Ru 4 (CO) 9 )] [M=Ru(CO), Ni II , Pd II , Pt II ] . The docking of the ruthenium clusters to azuliporphyrinogens with unoccupied cavities is documented as well …”

“…Thus, in spite of Co(CO) n (n = 2o r3 ,p resumably) binding, the inner cavity remained intact. The upfield relocations of the H21 and NH resonances and marked downfield shifts of b-H signals (8.58-8.24 ppm), compared with weakly aromatic azuliporphyrin 1 [9a] or nonaromatic porphyrinogens, [12] reveal the enhanced macrocyclic aromaticity of the macrocycle.…”

Phenanthrene cyclocarbonylation – core post-synthetic modification of phenanthriporphyrin

“…Thus 1-H 2 2+ , 2-H 2 2+ and 7-H 2 2+ reveal the carbocation electronic structure at least by 1 H NMR standards. 52–54…”