Confusion, inversion, and creation - A new spring from porphyrin chemistry

Core modified porphyrins – a macrocyclic platform for organometallic chemistry

Cyclo[8]pyrrole: A Simple-to-Make Expanded Porphyrin with No Meso Bridges

Blooming of confused porphyrinoids—fusion, expansion, contraction, and more confusion

Weak metal−arene interactions have been investigated in Zn, Cd, Hg, and Ni complexes of meso-tetraaryl m- and p-benziporphyrin (1 and 2) and of the new compound, m-benziporphodimethene (3). Compounds 1−3 incorporate the phenylene moiety into a macrocyclic structure so as to facilitate the interaction between the arene and coordinated metal ion. X-ray studies performed on Cd(II) and Ni(II) complexes show that the arene fragment approaches the ion at a distance much shorter than the sum of van der Waals radii. In chloronickel(II) m-benziporphyrin, a weak agostic bond is actually formed. In the NMR spectra of the Cd(II) and Hg(II) species, unusual 1H−M and 13C−M scalar couplings have been observed that are transmitted directly between the metal and the arene. DFT calculations performed for two Cd(II) species and subsequent AIM analysis show that the accumulation of electron density between the metal and arene necessary to induce these couplings is fairly small and the interaction is steric in nature. In the ...

Cadmium(II) and Nickel(II) Complexes of Benziporphyrins. A Study of Weak Intramolecular Metal−Arene Interactions

Pyrrole-2,4-dicarboxaldehydes 13a−c were condensed with a tripyrrane dicarboxylic acid 12 in 1% TFA−CH2Cl2 to give, following oxidation with 0.1% FeCl3, a series of “etio-type” N-confused porphyrins 14a−c. Excellent yields were obtained when the diformylpyrrole possessed a 5-alkyl substituent, although the products were most easily isolated in the form of their hydrochloride salts. Addition of TFA to the free base inverted porphyrins led to initial protonation onto the external nitrogen atom to produce monocations 19 and further acidification afforded a dications 21. UV−vis spectroscopy showed strong Soret bands for 14, 19, and 21, features that are associated with fully aromatic porphyrinoid systems, and proton NMR spectroscopy confirmed the presence of powerful diamagnetic ring current where the meso-protons resonated near 10 ppm while the interior CH was strongly shielded to −6 ppm for the free base structures and −4 ppm for the dications 21. Taking into account the effect of the introduction of deloca...

Conjugated macrocycles related to the porphyrins. part 16.1 synthesis of hexa- and heptaalkyl-substituted inverted or n-confused porphyrins by the 3 + 1 methodology

Timothy D. Lash

Papers

Conjugated macrocycles related to the porphyrins. part 16.1 synthesis of hexa- and heptaalkyl-substituted inverted or n-confused porphyrins by the 3 + 1 methodology