Lesyng B, Saenger W
Biochim Biophys Acta. 1978 Nov 15;544(1):215-24. doi: 10.1016/0304-4165(78)90224-6.
Theoretical investigations (Perturbative Configuration Interaction over Localized Orbitals (PCILO) and Intermediate Neglect of Differential Overlap (INDO) methods) of the conformation of tetramethylcystosine, an overcrowded molecule with planar structure, have been carried out. The physical features of rotational bending potentials of the dimethylamino group are discussed. Particularly, the controversial problem concerning the planarity of the molecule is investigated. The obtained results show that the planarity of tetramethylcytosine is an intrinsic property of the molecule. Nevertheless, because of the repulsion between the methyl groups, the planar structure of tetramethylcytosine is slightly destabilized. Further, the functional dependence of the dipole moment of tetramethylcytosine on rotation and bending of the dimethylamino group has been analyzed.
对具有平面结构的过度拥挤分子四甲基胞嘧啶的构象进行了理论研究（定域轨道微扰组态相互作用（PCILO）和间略微分重叠（INDO）方法）。讨论了二甲基氨基旋转弯曲势的物理特征。特别地，研究了有关该分子平面性的有争议问题。所得结果表明，四甲基胞嘧啶的平面性是该分子的固有性质。然而，由于甲基之间的排斥作用，四甲基胞嘧啶的平面结构略有失稳。此外，还分析了四甲基胞嘧啶偶极矩对二甲基氨基旋转和弯曲的函数依赖性。
