Abstract: 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.

Key words: NMR, diperoxovanadate, 2-methyl-imidazole, Interactions
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