铱羰基碘配合物的制备及羰基基团变化研究

Preparation of Iridium Iodocarbonyl Complexes and Study on the Change of Carbonyl Group

铱羰基碘配合物是目前工业上应用羰基合成法生产醋酸的主催化剂,对羰基变化过程的研究有利于加强对催化剂失活过程的认识。采用^(13)C NMR(核磁共振)等手段对制备的不同结构的铱羰基碘配合物进行表征。通过制备^(13)CO标记的铱羰基碘配合物,证实在高水质量分数的醋酸体系中主要以活性中心cis-[Ir(13CO)_2I_2]-的形式存在,在无^(13)CO氛围保护的加热条件下易氧化并失去^(13)CO,推测形成[Ir(^(13)CO)I_4(H_)2O)]-和[Ir(^(13)CO)I_4]_2^(2-);在低水质量分数的醋酸体系中主要以[HIr(^(13)CO)_2I_3]-和cis-[Ir(^(13)CO)_2I_4]-的形式存在,在无^(13)CO氛围保护的加热条件下失去^(13)CO,推测形成[Ir(^(13)CO)I_4]_2^(2-)及其同分异构体。

Iridium iodocarbonyl complexes are used as main catalysts for the production of acetic acid using carbonylation technique in current industry, and the understanding of catalyst deactivation process can be enhanced by the study of the change of carbonyl group. The iridium iodocarbonyl complexes with different structures were prepared and characterized by^（13） CNMR and other methods. By preparing~（^（13））CO-labelled iridium iodocarbonyl complexes, it was confirmed that cis-[Ir（^（13）CO）2I2]-was the main active center form in the acetic acid system with high water content, which was easy to be oxidized and lost^（13） CO when heated without^（13） CO protection, and the products were speculated to be[Ir（^（13）CO）I4（H2O）]-and [Ir（^（13）CO）I4]2^（2-）. In the acetic acid system with low water content, [HIr（^（13）CO）2I3]-and cis-[Ir（^（13）CO）2I4]-were the main active center forms, which would lose^（13） CO when heated without^（13） CO protection, and the products were speculated to be [Ir（^（13）CO）I4]2^（2-）and its isomer.