一种镍的二胺和β-二酮混合配体配合物在不同醇中热致-溶致变色行为的可见光谱研究

用可见光谱法对一种Ni(II)的二胺和β-二酮类混合配体配合物(Ni(II)(Me4en)(acac)]ClO4)在四种醇类溶剂中所形成的正方平面体和变形八面体物种的平衡过程进行了研究. 通过对配合物在醇中的热致-溶致变色光谱曲线的分峰拟合处理, 计算出了这一过程的平衡常数, 焓变△H和熵变△S等热力学函数, 同时, 得到了正方平面体和变形八面体物种各自的光谱吸收曲线. △H数据表明, 在醇中形成变形八面体物种是一个放热过程, 放热量的大小反映了醇分子与配合物中心离子Ni(II)配位能力的强弱. △S的绝对值与中心离子Ni(II)配位的或释放的醇分子数相关. 计算结果对深化认识Ni(II)的二胺和β-二酮类混合配体配合物热致变色的本质有所帮助.

Vis-Spectrum Investigation of Thermo-Solvatochromic Behaviors of a Mixed Diamine and β-Diketonate Ligand Ni(II) Complex in Different Alcoholic Solutions

Equilibria between square planar and pseudo octahedral species of the mixed diamine/β-diketonate Ni(II) complex (Ni(II)(Me4en)(acac)]ClO4) in four kinds of alcoholic solvents were investigated by means of Vis-spectra. Equilibriumconstants and thermodynamic parameters, which included enthalpy changes (△H) and entropy changes (△S), were evaluated from peak fitting the thermo-solvatochromic Vis-spectra of this complex in the alcoholic solutions. Spectra of the involved square planar and the pseudo octahedral species were also derived from the same analysis. △H data showed that the formation of the pseudo octahedral species was exothermic and the △H values reflect the coordination ability of alcoholic solvents with the central Ni(II) ion. Absolute values of △S relate to the number of liberated alcohol molecules or those coordinated to the central Ni(II) ion. The calculation results are helpful to thoroughly understand the thermochromic behavior of the mixed diamine/β-diketonate ligand Ni(II) complex.