双卟啉双钴配合物与双氧作用的热力学及ESR研究

Thermodynamic and ESR Study on the Reaction of Dicobalt(Ⅱ) Diporphyrin Complex with Dioxygen

用电子光谱法研究了一种由六个碳原子的脂肪二酰胺链连接两个四苯基卟啉的双核钴 (Ⅱ )配合物 (Co2 PP4 )在DMF溶液中与双氧的可逆结合作用 ,测定了反应的Hill系数n =1.84,ΔG0 ( 2 98K) =- 12 .3kJ·mol-1,P1/2 =6.8kPa ,热力学数据表明Co2 PP4 分子内两个金属卟啉环之间存在着强的协同作用 .由双卟啉双钴 (Ⅱ )配合物与双氧作用形成的配合物经ESR证实为超氧金属配合物 ,结合方式属于Co -O-2

The reaction of dioxygen with a dicobalt di(meso-tetraphenylporphyrin) linked by a diamido-aliphatic chain in N,N-dimethylformamide solution was studied.Thermodynamic values under standard state(298K,100kPa O_2)are: P_ 1/2=6.8kPa,n=1.84,ΔG 0=-12.3kJ·mol -1,ΔH 0=-172.09kJ·mol -1,ΔS 0=-536.21 J·mol -1·K -1. Thermodynamic data show that each of the two cobalt(Ⅱ) porphyrin rings has strong cooperative effect of oxygen binding with another. The reaction of dioxygen with the complex was also studied by ESR spectroscopy. The results show that bonding way of dioxygen complex is of the superoxo Co-O -_2 type.