Synthesis, Characterization and Biomimetic Activity of Heterogenized Dioxidomolybdenum(VI) Complex and Its Homogeneous Analogue

Cis-[(MoO2)-O-VI(CH3-hptb)(MeOH)] (1) has been synthesized by the reaction of [(MoO2)-O-VI(acac)(2)] and deferasirox [ICL670: 4-[3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazol-1-yl]benzoic acid, H(3)hptb, I] in 1:1 molar ratio in MeOH. Complex 1 has been characterized successfully by several spectral techniques, viz. FT-IR, UV-Vis, H-1 and C-13 NMR, elemental (CHN) and thermogravimetric analysis. The esterification of the carboxylic group of ligand was observed during the complexation process with molybdenum. The analogous heterogeneous complex [(MoO2)-O-VI(hptb)(MeOH)]@APTMS-TiO2 (2) has been synthesized by immobilizing I on amine-functionalized TiO2, {[H(2)hptb]@APTMS-TiO2 (II)} and then reacting it with [(MoO2)-O-VI(acac)(2)] in MeOH. Characterization of the immobilized complex was achieved through FT-IR, DRS, P-XRD, TEM, thermogravimetric analysis and MP-AES. Both the complexes have been utilized in synthesizing organobromine compounds through oxidative bromination of styrene in the presence of KBr, oxidant (30% aq. H2O2) and 70% aq. HClO4 at room temperature. With the formation of 2-bromo-1-phenylethane-1-ol and 1-phenylethane-1,2-diol under the optimized reaction conditions, 72 and 100% conversion of styrene was achieved in the presence of catalysts 1 and 2, respectively. The oxidative bromination of thymol with catalyst 2 provides 2-bromothymol (52%) and 2,4-dibromothymol (48%) with 100% conversion.

Automated summary

Two molybdenum-centered complexes were synthesized and used as catalysts for organic bromination reactions. Catalyst 2 was immobilized on TiO2 and reacted with a precursor in methanol to achieve the desired complex.