Abstract:

A new functional monomeric complex of oxovanadium(Ⅳ), VO(imidazole)₄(SO₄)·H₂O(1) was synthesized from the reaction of VOSO₄·nH₂O with imidazole in methanol at room temperature. The complex was characterized by elemental analysis, IR spectrometry and single crystal X-ray diffraction. Structure analysis reveals that complex 1 crystallized in an orthorclinic system with space group Pna21, a=1.384 4(3) nm,b=0.978 6(2) nm,c=1.361 7(3) nm,α=β=γ=90°,V=1.844 7(6) nm3,Z=4. Bromination reaction activity of the complex was evaluated by the method with phenol red as organic substrate in the presence of H₂O₂, Br- and phosphate buffer. The reaction rate constant(k) for complex 1 was calculated as 2.760 0×10⁷ L²/(mol²·s). The electronic structure and the bonding characters of the complex were analyzed with ab initio calculation. The atomic net charge distribution in the molecular system indicates obvious covalent interaction between the coordinating atoms and vanadium, the bond order of V—O1(1.0553) is obviously larger than that of V—O2(0.3942), the bond order of the four V—N bonds(0.3336～0.3419) is similar. The results are consistent with the structure analysis of the complex.

Key words: Oxovanadium complex, Imidazole, Catalytic activity, Crystal structure, Quantum chemistry