I_2-环己烯复合物的共振拉曼光谱和密度泛函理论计算研究

Resonance Raman Spectroscopy and Density Functional Theory Calculation Investigation of I_2-cyclohexene Complex

实验得到 I2 -环己烯电荷转移复合物的电子吸收光谱和共振拉曼光谱 .用密度泛函方法计算了复合物的基态结构、振动频率和电子跃迁能 .计算和吸收光谱实验结果表明 ,I2 -烯烃复合物在约 3 0 0 nm处的强吸收带为 pz( I1 7)→π* ( C=C)跃迁 ,即由靠近 C C双键端的碘原子 ( I1 7)上的一个 pz 电子向 C=C双键反键轨道跃迁引起的吸收 .在约 3 0 0 nm共振拉曼光谱的强度模式表现为 I— I伸缩振动模和 C=C伸缩振动模的基频、泛频及其组合频 ,表明在该激发态上 I2 -环己烯复合物经历了显著的 I—I和

Resonance Raman spectra of I 2-cyclohexene charge-transfer complex were obtained with three excitations at ~300 nm absorption band of the complex. Density functional theory calculations were carried out to examine the structure and normal mode frequencies of the ground state of the complex and its electronic transition energies. The strong absorption band around 300 nm was assigned to p z (I17)→ π *(\{CC\}) transition,that is the transition of a p z electron from I atom at CC terminal to anti-bonding orbital of CC double bond. The resonance Raman spectra displayed the Raman intensity in the overtones and combination bands of the nominal I—I stretch and CC stretch modes.This suggested that the complex underwent an obvious valence change in both I—I and CC.