Stretch Effects Induced by Molecular Strain on Weakening 蟽-Bonds: Molecular Design of Long-Lived Diradicals (Biradicals)

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• 作者：Manabu Abe ; Haruka Furunaga ; Dongxia Ma ; Laura Gagliardi ; Graham J. Bodwell
• 刊名：The Journal of Organic Chemistry
• 出版年：2012
• 出版时间：September 7, 2012
• 年：2012
• 卷：77
• 期：17
• 页码：7612-7619
• 全文大小：399K
• 年卷期：v.77,no.17(September 7, 2012)
• ISSN：1520-6904

文摘

Stretch effects induced by two types of molecular strain were examined by quantum chemical calculations at the B3LYP/6-31G(d), B3LYP/cc-PVDZ, CCSD/6-31G(d), and CASPT2/ANO-RCC-VTZP level of theory, to design persistent multiradicals such as localized diradicals and oxyallyls. The cooperative molecular strain (Type-1) induced by the spiro[5.5]undecane and bicyclo[2.1.0]cyclopentane structures was found to significantly destabilize in energy the ring-closed compounds of the diradicals, leading to small energy differences between the diradicals and the 蟽-bonded compounds. Another stretch effect (Type-2) induced by macrocyclic systems was also found to energetically destabilize the corresponding ring-closed structures of the 1,3-diradicals. The computational studies predict that the two types of stretch effects are quite effective in lowering the energy barriers of the bond-breaking reaction of the ring-closed compounds and in generating long-lived localized diradicals and oxyallyl derivatives.