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meta ‐ and para ‐Phenylenediamine‐Fused Porphyrin Dimers: Synthesis and Magnetic Interactions of Their Dication Diradicals
Author(s) -
Kato Kenichi,
Osuka Atsuhiro
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201901939
Subject(s) - diradical , dication , porphyrin , chemistry , intramolecular force , photochemistry , nickel , delocalized electron , phenylene , singlet state , stereochemistry , molecule , excited state , organic chemistry , physics , nuclear physics , polymer
meta ‐ and para ‐Phenylenediamine‐fused nickel(II) porphyrin dimers were synthesized by S N Ar reaction of meso ,β,β‐trichloro nickel(II) porphyrin with meta ‐ and para ‐phenylenediamines and subsequent Pd‐catalyzed intramolecular C−H arylation. Their tetrachlorinated dication diradicals are very stable, allowing SQUID magnetometry and revealing clear open‐shell characters for both meta and para isomers with ferro‐ and anti‐ferromagnetic interactions, respectively. The nitrogen analogue of Thiele's hydrocarbon usually displays predominant closed‐shell nature but its hidden diradical characters increase either in a twisted conformation or upon insertion of an additional phenylene spacer. The observed distinct diradical nature of the para ‐congener indicates that diradical properties can be enhanced also by efficient spin delocalization.