Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo, Norway.
J Phys Chem A. 2009 Nov 19;113(46):12904-10. doi: 10.1021/jp907199h.
The synthesis of a 2-halogenoethylphosphine, (2-chloroethyl)phosphine (ClCH(2)CH(2)PH(2)), is reported for the first time. This compound was prepared by a chemoselective reduction of diethylchloroethylphosphonate with dichloroalane using a vacuum line. (2-Chloroethyl)phosphine has been studied by microwave spectroscopy at room temperature, or at -20 degrees C, in the 22-80 GHz spectral interval. The experimental study has been augmented by quantum chemical calculations at the MP2/6-311++(3df,3pd) and B3LYP/6-311++(3df,3pd) levels of theory. The spectra of two rotameric forms, denoted I and II have been assigned. These conformers both have an antiperiplanar arrangement for the Cl-C-C-P chain of atoms, but with different orientation of the phosphine group. Conformer I was found to be 5.2(6) kJ/mol more stable than II by relative intensity measurements. The spectra of the first excited states of the C-C torsional vibration of both I and II were assigned. The torsional frequency was determined to be 63(20) cm(-1) for conformer I by relative intensity measurements, and it has a similar value in II. It was found that this normal vibration deviates from a near-harmonic behavior. The quantum chemical calculations produce rotational and centrifugal distortion constants that are in satisfactory agreement with observations, but fail to predict correctly low-frequency fundamental frequencies. The quantum chemical calculations indicate that three additional conformers characterized by a synclinal orientation for the Cl-C-C-P link of atoms and with different orientation of the phosphine group are high-energy forms of ClCH(2)CH(2)PH(2). Searches for these forms were unsuccessful.
首次报道了 2-卤代乙基膦，（2-氯乙基）膦（ClCH(2)CH(2)PH(2)）的合成。该化合物是通过在真空线中使用二氯代乙膦酸二乙酯与二氯代铝烷选择性还原制备的。（2-氯乙基）膦在室温或-20°C 下，在 22-80GHz 光谱间隔内通过微波光谱进行了研究。实验研究通过在 MP2/6-311++(3df,3pd)和 B3LYP/6-311++(3df,3pd)理论水平上的量子化学计算得到了补充。分配了两种旋转异构体，分别表示为 I 和 II。这两种构象都具有原子 Cl-C-C-P 链的反式平面排列，但膦基的取向不同。通过相对强度测量发现构象 I 比 II 稳定 5.2(6)kJ/mol。分配了 I 和 II 的 C-C 扭转振动的第一激发态的光谱。通过相对强度测量确定构象 I 的扭转频率为 63(20)cm(-1)，在 II 中也具有相似的值。发现该简谐振动偏离近谐振动行为。量子化学计算产生的旋转和离心畸变常数与观察结果非常吻合，但未能正确预测低频基频。量子化学计算表明，三个具有原子 Cl-C-C-P 键的顺式取向和膦基不同取向的额外构象是 ClCH(2)CH(2)PH(2)的高能形式。但未能搜索到这些构象。
