Abstract: Studies on the band positions in IR spectra of Co₂(CO)₈ with the C_2v symmetry and the catalytic activities of the species, HCo(CO)3 and HCo(CO)4,in the reaction of the olefin hydroformylation have been carried out by using quantum chemical calculation at the B3LYP/6-3 1G* level. Two structures of the Co₂(CO)₈, the geometry of C_2v symmetry, as well as the conformation of D_3d symmetry, have been optimized and the structure optimized of C_2v symmetry Co₂(CO)₈ agrees well with experimental structure and is 28.80kJ/mol more stable than D_3d one. The band pos itions in IR spectra of C_2v symmetry Co₂(CO)₈ is well in accord with the experimental studies. It is found that the active catalytic species, HCo(CO)₃ and HCo(CO)₄, have C_2v and C_3vsymmetries, respectively, and that the catalytic activity of HCo(CO)₃ is better than HCo(CO)₄. In addition, the π bond between ethene and HCo(CO)₃ has been formed in the coordinate catalytic reaction and the theoretical bond energy is 100.80kJ/mol.

Key words: Octacarbonyldicobalt, HCo(CO)₃, HCo(CO)₄, electronic structure, IR spectra, catalytic activity

摘要： 在B3LYP/6-31G*水平上对Co₂(CO)₈红外光谱及烯烃氢甲酰化催化反应的催化活性中间体HCo(CO)₄和HCo(CO)₃的结构进行了优化及相关计算，结果表明：(1) Co₂(CO)₈的两种稳定构象态分别具有C_2v和D_3d对称性，计算所得的结构数据与实验 值具有极好的一致性。C_2v对称性的Co₂(CO)₈比D_3d对称性的Co₂(CO)₈的能量低28.80kJ/mol; (2) C_2v对称性的Co₂(CO)₈的红外吸收峰的计算结果 与实验值极为接近；(3) 催化反应的活性中间体HCo(CO)4和HCo(CO)3的稳定构象 态分别具有C_3v和C_2v对称性，其中HCo(CO)₃比HCo(CO)₄具有更高的催化活性；(4) 催化反应中乙烯与HCo(CO)3形成了相对稳定的π配合物，该配合物中π配键的键能约为100.80kJ/mol。

关键词: 八羰基合二钴, 三羰基一氢合钴, 四羰基一氢合钴, 电子结构, 红外光谱, 催化活性