【摘要】 本文应用UHF-INDO方法研究了氰乙酸自由基的结构.计算了氰乙酸自由基的本征值.本征向量、价电子密度、自旋密度、各向异性耦合常数、各向同性耦合常数以及总能量、键能和偶极矩:计算的各向同性耦合常数和各向异性耦合常数与实验值符合很好.更多还原

【Abstract】 UHF-INDO LCAO SCF MO calculations of cyanoacetio acid free radical (NCCHCOOH)were carried out. The program used is Pople’s CNINDO. Data calculated for radical structure of cyanoacetic acid are presented and compared with available experimental results in Tables 1 and 2 and Fig. 2～7 in the Chinese Text.It is confirmed by ESR spectra study and INDO calculation that the free radical trapped in the irradiated single crystal of cyanoacetic acid is in the form of NCCHCOOH. Molecular orbital coefficient, electron density, net atomic charge, spin density and hyperfine coupling constant are calculated for NCCHCOOH radical.Calculations of the isotropic hyperfine coupling constants and the total energy as a function of the NC--C--and--COOH torsion angle θ were carried out and the planar conformation is established in correspondence with a minimum in the total energy of the potential barrier of internal rotation about the carbon-carbon bond calculated to be 7.22 kcal/mol. The isotropic hyperfine coupling constant varies with different torsion angle θ. The best agreement between calculated and observed isotropic constants is found for θ=37°.更多还原