Novel oxovanadium complexes (VO)2(bpz*T-O) (1), VO(bpz*eaT)(SCN)2 (2), V2(bpz*eaT)2(μ2-C2O4)(C2O4)2 (3), [VO(SO4)(bpz*P)(H2O)]·H2O (4) and VO(SO4)(bpz*P-Me)(H2O) (5) (bpz*T-O: 4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazin-2-olate, bpz*eaT: 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-diethylamino-1,3,5-triazine, bpz*P: 2,6-bis(5-methyl-pyrazol-3-yl)pyridine, bpz*P-Me: 2,6-bis(1,5-dimethyl-pyrazol-3-yl)pyridine), were synthesized by the reaction of V2(SO4)3–VOSO4–VO(acac)2 and various pincer N-heterocyclic ligands with solution or hydrothermal methods. The structures of all the complexes were characterized by elemental analysis, IR and UV-vis spectroscopy and single-crystal diffraction analysis. Furthermore, thermogravimetric analyses (TG) and quantum chemistry calculations were also performed. Structural analyses reveal that the vanadium atom has a distorted trigonal bipyramidal geometry with a N3O2 donor set in 1; distorted octahedral geometry in 2, 4 and 5 with donor sets of N5O, N3O3 and N3O3, respectively; a distorted pentagonal bipyramidal geometry with a N3O4 donor set in 3. In addition, the five new complexes with abundant intro- and inter-hydrogen bonding interactions exhibited bromination catalytic activity in a single-pot reaction of the conversion of phenol red to bromophenol blue in a mixed solution of H2O–DMF at a constant temperature of 30 ± 0.5 °C with a buffer solution of NaH2PO4–Na2HPO4 (pH = 5.8), indicating that they can be considered as a potential functional model of bromoperoxidase.
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