We report an unexpected rearrangement, controlled by the nature of the bridge, leading to the formation of novel, remarkably stable triply fused dinickel(II)/dicopper(II) chlorin-porphyrin dication diradical heterodimers in excellent yields. Here, a dipyrromethene bridge gets completely fused between two porphyrin macrocycles with two new C-C and one C-N bonds. The two macrocycles exhibit extensive pi-conjugation through the bridge, which results in an antiferromagnetic coupling between the two pi-cation radicals. In addition, the macrocyclic distortion also favours a rare intramolecular ferromagnetic interaction between the Cu-II and pi-cation radical spins to form a triplet state. The structural and electronic perturbation in the unconjugated dication diradical possibly enables the bridging pyrrolic nitrogen to undergo a nucleophilic attack at the nearby beta-carbon of the porphyrin pi-cation radical with a computed free energy barrier of >20 kcal mol(-1) which was supplied in the form of reflux condition to initiate such a rearrangement process. UV-vis, EPR and ESI-MS spectroscopies were used to monitor the rearrangement process in situ in order to identify the key reactive intermediates leading to such an unusual transformation.

Stable Dication Diradicals of Triply Fused Metallo Chlorin‐Porphyrin Heterodimers: Impact of the Bridge on the Control of Spin Coupling to Reactivity / Shah, Syed Jehanger; Pandit, Younis Ahmad; Garribba, Eugenio; Ishida, Masatoshi; Rath, Sankar Prasad. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - 29:64(2023), p. e202301963. [10.1002/chem.202301963]

Stable Dication Diradicals of Triply Fused Metallo Chlorin‐Porphyrin Heterodimers: Impact of the Bridge on the Control of Spin Coupling to Reactivity

Garribba, Eugenio;
2023-01-01

Abstract

We report an unexpected rearrangement, controlled by the nature of the bridge, leading to the formation of novel, remarkably stable triply fused dinickel(II)/dicopper(II) chlorin-porphyrin dication diradical heterodimers in excellent yields. Here, a dipyrromethene bridge gets completely fused between two porphyrin macrocycles with two new C-C and one C-N bonds. The two macrocycles exhibit extensive pi-conjugation through the bridge, which results in an antiferromagnetic coupling between the two pi-cation radicals. In addition, the macrocyclic distortion also favours a rare intramolecular ferromagnetic interaction between the Cu-II and pi-cation radical spins to form a triplet state. The structural and electronic perturbation in the unconjugated dication diradical possibly enables the bridging pyrrolic nitrogen to undergo a nucleophilic attack at the nearby beta-carbon of the porphyrin pi-cation radical with a computed free energy barrier of >20 kcal mol(-1) which was supplied in the form of reflux condition to initiate such a rearrangement process. UV-vis, EPR and ESI-MS spectroscopies were used to monitor the rearrangement process in situ in order to identify the key reactive intermediates leading to such an unusual transformation.
2023
Stable Dication Diradicals of Triply Fused Metallo Chlorin‐Porphyrin Heterodimers: Impact of the Bridge on the Control of Spin Coupling to Reactivity / Shah, Syed Jehanger; Pandit, Younis Ahmad; Garribba, Eugenio; Ishida, Masatoshi; Rath, Sankar Prasad. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - 29:64(2023), p. e202301963. [10.1002/chem.202301963]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/325006
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