The Bergman cyclization is the process of enediyne cyclizing into the highly reactive diradical <i>p</i>-benzene. Diradicals such as these are reactive, short lived and have an affinity for hydrogen abstractions and the potential to be used as a cancer treatment. However, these diradical based drugs do not differentiate between cancerous and non-cancerous cells. A more complete understanding of this structure in the Bergman Cyclization is crucial in the attempt to create more effective cancer treatments. The cyclization of the hexa-3-ene-1, 5-diyne system has been studied extensively, but the penta-1, 4-diyne anion, hepta-1, 6-diyne cation and octa-1, 7-diyne dication systems have not yet been studied. The cyclization of these three molecules produce enediynes similar in structure and function to that of p-benzene and further studying the formation of their diradicals will assist in a greater understanding the character of these diradicals and their potential as anti-cancer agents. The Bergman cyclization of the hepta-1, 6-diyne cation was characterized using spin flip couple cluster (SF-CCSD) method. The activation barrier and energy of the reaction along with the adiabatic and vertical gaps for the singlet and triplet states were calculated using ROHF-SF-CCSD(T)/cc-pVTZ single-point calculations. The reaction energy was calculated to be -1.49 kcal/mol (indication of an exothermic reaction) while the singlet-triplet adiabatic gap was calculated to be 0.6151 kcal/mol.

Spin-flip characterization of the Bergman cyclization of the hepta-1,6-diyne system

2019 Spring National Meeting

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