Benzene- and pyridine-incorporated octaphyrins with different coordination modes toward two PdII centers
Le Liu, Zhiwen Hu, Fenni Zhang, Yang Liu, Ling Xu, Mingbo Zhou, Takayuki Tanaka, Atsuhiro Osuka, Jianxin Song
Abstract
Abstract Expanded porphyrins have received considerable attention due to their unique optical, electrochemical and coordination properties. Here, we report benzene- and pyridine-incorporated octaphyrins(1.1.0.0.1.1.0.0), which are synthesized through Suzuki-Miyaura coupling of α,α′-diboryltripyrrane with m- dibromobenzene and 2,6-dibromopyridine, respectively, and subsequent oxidation with 2,3-dicyano-5,6-dichlorobenzoquinone. Both octaphyrins are nonaromatic and take on dumbbell structures. Upon treatment with Pd(OOCCH 3 ) 2 , the benzene-incorporated one gives a C i symmetric NNNC coordinated bis-Pd II complex but the pyridine incorporated one gives C i and C s symmetric NNNC coordinated bis-Pd II complexes along with an NNNN coordinated bis-Pd II complex bearing a transannular C–C bond between the pyrrole α-positions. In addition, these two pyridine-containing NNNC Pd II complexes undergo trifluoroacetic acid-induced clean interconversion.