【摘要】 使用半经验量子化学中的AM1方法、从头计算Hartree-Fock理论(在3-21G*水平)和密度泛函理论中的B3LYP方法(使用6-31G(d)基组),研究了尿酸分子的所有35种互变异构体。计算结果表明,三羰基互变异构体是所有异构体中能量最低的,其次为单羟基异构体和双羟基异构体,而含有三羟基的互变异构体相对能量最高。随着羟基数的增加, C-N键的平均键长从1.395逐渐缩短到1.351,而CC键的平均键长基本保持不变(1.400~1.406)。更多还原

【Abstract】 Semiempirical quantum chemistry method AM1, Hartree-Fock method at 3-21G* basis set level and density functional method at B3LYP/6-31G(d) basis set level were employed to study the total 35 tautomers with planar conformational isomer of molecule uric acid. The calculated results show that the tricarbonyl tautomer is the most stable and the trihydroxy tautomer is the most unstable of all 35 tautomers, which is in agreement with the experiment. The bond lengths and bond population analysis are presented in this paper. The average CN bond lengths became shorter when the amount of hydroxy groups in tautomers increased and the average CC bond lengths had no remarkable chang in all tautomers.更多还原