HXeCCH...CO₂ 配合物的矩阵隔离与从头算研究。

Tanskanen Hanna, Johansson Susanna, Lignell Antti, Khriachtchev Leonid, Räsänen Markku

Laboratory of Physical Chemistry, P.O. Box 55, University of Helsinki, Helsinki FIN-00014, Finland.

J Chem Phys. 2007 Oct 21;127(15):154313. doi: 10.1063/1.2780846.

The HXeCCH...CO2 complex is studied experimentally and computationally. The complex is prepared in a low-temperature xenon matrix using UV photolysis of propiolic acid (HCCCOOH) and thermal mobilization of H atoms at 45 K. Photolysis of propiolic acid leads to the HCCH...CO2 complex as one of the photolysis products. The HCCH...CO2 complex is further photolyzed to the HCC...CO2 complex. Thermal annealing leads to the formation of HXeCCH complexed with CO2. The H-Xe stretching absorption of the HXeCCH...CO2 complex is blueshifted (+31.9 and +5.8 cm(-1)) from the value of the HXeCCH monomer in a xenon matrix. In the calculations, three HXeCCH...CO2 structures were found (one parallel and two linear structures) corresponding to the true energy minima on the potential energy surface. For the H-Xe stretching mode, the calculations give blueshifted values of +19.2 or +19.5 cm(-1) depending on the computational level [MP2/6-311++G(2d,2p) and MP2/aug-cc-pVDZ] for the parallel structure and +19.4 or +27.9 cm(-1) for one linear structure. For the second linear structure, the H-Xe stretching frequency is redshifted by -8.6 or -9.4 cm(-1) at these levels of theory. Based on the calculations, the experimental band shifted by +5.8 cm(-1) (1492.2 cm(-1)) most likely corresponds to the HXeCCH...CO2 parallel structure. The band with larger blueshift of +31.9 cm(-1) (1518.3 cm(-1)) can be due to another matrix site of the same structure or to the blueshifting linear structure.

对HXeCCH...CO₂复合物进行了实验和计算研究。该复合物是在低温氙基质中通过丙炔酸（HCCCOOH）的紫外光解以及45K下H原子的热迁移制备的。丙炔酸的光解产生了HCCH...CO₂复合物作为光解产物之一。HCCH...CO₂复合物进一步光解为HCC...CO₂复合物。热退火导致形成与CO₂络合的HXeCCH。HXeCCH...CO₂复合物的H-Xe伸缩吸收相对于氙基质中HXeCCH单体的值发生了蓝移（+31.9和+5.8 cm⁻¹）。在计算中，发现了三种HXeCCH...CO₂结构（一种平行结构和两种线性结构），它们对应于势能面上的真实能量最小值。对于H-Xe伸缩模式，根据计算水平[MP2/6-311++G(2d,2p)和MP2/aug-cc-pVDZ]，平行结构的计算给出的蓝移值为+19.2或+19.5 cm⁻¹，一种线性结构的蓝移值为+19.4或+27.9 cm⁻¹。对于第二种线性结构，在这些理论水平下，H-Xe伸缩频率红移了-8.6或-9.4 cm⁻¹。基于计算，实验中蓝移了+5.8 cm⁻¹（1492.2 cm⁻¹）的谱带最有可能对应于HXeCCH...CO₂平行结构。蓝移较大的+31.9 cm⁻¹（1518.3 cm⁻¹）的谱带可能是由于相同结构的另一个基质位点或蓝移的线性结构。