Department of Chemistry, University of Helsinki, Helsinki, Finland.
J Phys Chem A. 2012 Mar 8;116(9):2101-8. doi: 10.1021/jp209714e. Epub 2012 Feb 23.
We report on the first experimental observation of formic acid dimers composed of two molecules of the higher-energy cis conformer. The cis-cis formic acid dimers are prepared in an argon matrix by selective vibrational excitation of the ground state trans conformer (deuterated form HCOOD) combined with thermal annealing of the matrix at about 30 K. Five cis-cis formic acid dimers are predicted by ab initio calculations (interaction energies from -16.9 to -27.2 kJ mol(-1)), and these structures are used for the assignment of the experimental spectra. Selective vibrational excitation of the obtained cis-cis dimers leads to the formation of several trans-cis dimers, which supports the proposed assignments.
我们报告了首次实验观察到由两个较高能量顺式构象分子组成的甲酸二聚体。顺式-顺式甲酸二聚体通过选择性激发基态反式构象（氘代甲酸 HCOOD）并在约 30 K 的基质中进行热退火来制备。通过从头算计算预测了五个顺式-顺式甲酸二聚体（相互作用能从-16.9 到-27.2 kJ mol(-1))，这些结构用于实验光谱的分配。对获得的顺式-顺式二聚体的选择性振动激发导致形成几个反式-顺式二聚体，这支持了所提出的分配。
