双过氧钒配合物与2-甲基咪唑相互作用的NMR研究(英文)

Abstract

为探讨过氧钒配合物上有机配体对反应平衡的影响,在模拟生理条件下(0.15MOl/lnACl溶液)应用多核(1H,13C,和51V)多维(COSy和dOSy)nMr以及变温技术等谱学方法研究双过氧钒配合物[OV(O2)2l]n-{n=1~3,l=OXAlATE(缩写为OXA),PICOlInATE(缩写为PIC),bIPyrIdInE(缩写为bIPy),和1,10-PHEnAnTHrOlInE(缩写为PHEn),与它们配位的含钒物种分别缩写为bPV(OXA),bPV(PIC),bPV(bIPy)和bPV(PHEn)}与2-甲基咪唑(缩写为2-ME-IMI)的相互作用,实验结果表明2-ME-IMI与4种双过氧钒配合物的反应性从强到弱的顺序为:bPV(OXA)>bPV(PIC)>bPV(bIPy)>bPV(PHEn).研究表明金属中心上配体的配位能力和空间位阻都对反应平衡产生较大的影响关,键同词时:竞争配位的结果导致新的六配位的过氧物种[OV(O2)2(2-ME-IMI)]-的生成.

To understand the effects of organic ligands on reaction equilibrium,the interactions between diperoxovanadate complexes [OV(O2)2LL']n-(n=1--3; LL'=oxalate,picolinate,2,2'-bipyridine,and 1,10-phenanthroline) and 2-methyl-imidazole in 0.15 mol/L NaCl ionic medium,which was used to mimick physiological conditions,were explored using multinuclear (1H,13C,and 51V) NMR spectroscopy and variable temperature experiments.The experimental results indicated the reactivities of the four diperoxovanadate complexes with 2-methyl-imidazole were as follows:bpV(oxalate)>bpV(picolinate)>bpV(2,2'-bipyridine)>bpV(1,10-phenanthroline).Both the coordination capability and the steric effects of the organic ligands affected reaction equilibrium.New six-coordinated peroxovanadate species [OV(O2)2(2-methyl-imidazole)]-were formed due to competitive coordination.