过渡金属乙酰丙酮螯合物的体积排除色谱研究

SIZE EXCLUSION CHROMATOGRAPHY OF TRANSITION METAL CHELATES OF ACETYLACETONE

用体积排除色谱方法研究了过渡金属Fe(Ⅲ)、Co(Ⅲ)、Cu(Ⅱ)、Ni(Ⅱ)的乙酰丙酮螯合物在四氢呋喃溶液中的加合和缔合行为。在溶液中乙酰丙酮钴(Ⅲ)以单个螯合物分子的形式存在,乙酰丙酮铜(Ⅱ)和乙酰丙酮铁(Ⅲ)与溶剂加合生成加合物,乙酰丙酮铁(Ⅲ)除加合物外还存在缔合度为2-10的多分散缔合物,乙酰丙酮镍(Ⅱ)水合物在四氢呋喃中产生了加合交换作用,同时存在缔合度为6左右的缔合物。色谱数据给出了螯合物、加合物及缔合物的相对含量。螯合物与相同分子量的聚苯乙烯相比,其保留体积的滞后以Ni<Cu<Co<Fe的次序递增,与过渡金属的一级电离能的大小顺序一致。

The self-association and adduct formation of the transition metal chelates, viz, iron(III), cobalt(III), copper(II), nickel(II) of acetylacetone in tetrahydrofurane were investigated by size exclusion chromatography. Tris(acetylacetonato) cobalt(III) in the solution exists in the form of a single chelate molecule. Bis(acetylacetonato) copper(II) and Tris(acetylacetonato) iron(III) react with the solvent to form adducts. Tris(acetylacetonato) iron(III) in tetrahydrofurane also self-associated to form a polydisperse aggregate with association number from 2 to 10. Addition ligand exchanging is occured in tetrahydrofurane for bis(acetylacetonato) nickel(II ) hydrate and a small amount of aggregate with association number around 6 is also present. The relative contents of the chclate, adduct and aggregate are evaluated from the chromatographic data. The lag of the chromatographic retention values of the chelates relative to polystyrene with same molecular weight increase in the order of Ni < Cu < Co < Fe, which is the same as that of the first ionization energies of the transition metals.