A novel neutral diradical of π-extended phenalenyl derivative having three oxo-groups, tri-tert-butyl-1,4,7-trioxophenalenyl, and two types of the corresponding σ-dimers were investigated. Quantum chemical calculations showed that the neutral diradical is in triplet ground state having doubly degenerate singly occupied molecular orbitals. The neutral diradical undergoes a σ-dimerization, generating two types of σ-dimers immediately after the preparation. One of the σ-dimers, which was selectively generated in the crystalline state, was a close-shell dimer linked through double-σ-bonds on the phenalenyl skeleton with a long C-C bond length of 1.66 Å. The other σ-dimer, which existed only in the solution state, was a peroxy-linked open-shell dimer in which one σ-bond was formed between two oxygen atoms. Furthermore, the temperature-dependent H NMR and ESR spectra revealed that these σ-dimers are in equilibrium in the solution state by the reversible σ-bond formation/cleavage via the neutral diradical as a key intermediate.
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http://dx.doi.org/10.1002/chem.202201426 | DOI Listing |
Angew Chem Int Ed Engl
December 2024
School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore, Singapore.
Polycyclic aromatic diradical(oid) molecules are attracting significant attention because of their unique electronic and magnetic properties as well as their applications as functional materials. While diradical(oid) molecules bearing five-membered rings have been extensively investigated, those bearing seven-membered rings are relatively fewer. Herein, we report the synthesis of azapentabenzodihomocorannulene dication and diradical molecules.
View Article and Find Full Text PDFPhys Chem Chem Phys
December 2024
Department of Chemistry, Maynooth University, Maynooth, Co. Kildare, Ireland.
Chem Sci
November 2024
Division of Applied Chemistry, Faculty of Engineering, Hokkaido University Kita 13, Nishi 8, Kita-ku Sapporo Hokkaido 060-8628 Japan
A cyclo[4]pyrrole bearing pyrrole C()-C() direct linkages, a contracted porphyrin analogue with no -carbon bridge, was synthesized from an oligoketone-related precursor. X-ray crystallography and StrainViz analysis revealed a non-planar structure with a total strain of 20.8 kcal mol.
View Article and Find Full Text PDFSci Adv
November 2024
School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu 611731, P. R. China.
Uncovering the effects of radical injection into responsive organic molecules is a long-sought goal, and the single-molecule junctions provide a unique way to investigate molecular conductance evolution during the radical injection. We can modulate the main channel conductance by using electronic injection from off-site neutral radicals acting as gating terminals. Two families of cyclopentadienone derivatives were synthesized, featuring the inter-pyridyl main conductance channel and the inter-radical paths that are linear (FCF) or cross conjugated (PCP).
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany.
The isolation of silicon analogues of phenyl anions such as (CH) and (CH) is challenging owing to their extremely high reactivity associated with their silylene character and weak C-Si π-interaction. Herein, we report the first annulated 1,4-disilabenzene-1,4-diide compound [(ADC)Si] () based on anionic dicarbene (ADC) scaffolds (ADC = PhC{N(Dipp)C}; Dipp = 2,6-PrCH) as a green-yellow crystalline solid. Compound is prepared by KC reduction of the Si(IV) chloride [(ADC)SiCl] () or the cyclic bis-chlorosilylene [(ADC)SiCl] (), which are also prepared for the first time.
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