Zhen, Cian-Jhe; Lu, Shu-Feng; Lin, Min-Hwa; Wu, Jay-Tai; Chao, Ito; Lin, Chih-Hsiu published the artcile< Singlet Biradical Versus Triplet Biradical/Zwitterion Characteristics in Isomers of C6-C5-C6-C7-C6-Fused Pentacyclic Aromatic Hydrocarbons Revealed through Reactivity Patterns>, Category: bromides-buliding-blocks, the main research area is fused pentacyclic aromatic hydrocarbon biradical zwitterion structure property relationship; biradical; polycyclic aromatic hydrocarbons; structure property relationship; zwitterion.
Among various polycyclic aromatic hydrocarbons, C6-C5-C6-C7-C6 fused pentacyclic aromatic hydrocarbons have the unique potential to adopt quinonoid, zwitterion, singlet, or triplet biradical electronic configurations. Two such hybrid structures between pentacene and azulene were synthesized and their ground state electronic configurations were deduced from the reactivity patterns they exhibit resp. Compound I, where the radicaloid carbons are linked through a para-phenylene, forms a head-to-head dimer like a singlet biradical. In contrast, isomer II, where the para-linkage was switched to meta, reacts readily with oxygen which resembles the reactivity of a triplet state. The oxidized intermediate(s) then underwent rearrangement to furnish the C6-C5-C6-C6-C6 ring contraction product 11,13-Dimesityl-13H-indeno[1,2-b]anthracene-6-carbaldehyde. Cation 12,14-Dimesityl-12,14-dihydrobenzo[5,6]cyclohepta[1,2-b]fluoren-12-ylium tetrafluoroborate, the protonated form of compound II, was synthesized, which implies compound II also reacts like a zwitterion. It was revealed the oxidative rearrangement takes place even with mesityl dibenzotropylium cation despite its perceived aromaticity. DFT calculations confirm the most stable forms of compound I and compound II are singlet and triplet diradical, which is consistent with the observed reactivity of resp. mols.
Chemistry – A European Journal published new progress about Biradicals Role: FMU (Formation, Unclassified), FORM (Formation, Nonpreparative). 576-83-0 belongs to class bromides-buliding-blocks, and the molecular formula is C9H11Br, Category: bromides-buliding-blocks.
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary