Controllable Synthesis of Lindqvist Alkoxopolyoxovanadate Clusters as Heterogeneous Catalysts for Sulfoxidation of Sulfides

Six alkoxohexavanadate-based Cu- or Co-POVs [Cu(dpa)(acac)(H2O)](2)[V6O13(OMe)(6)] (I), [Cu(phen)(acac)(MeOH))(2)[V6O13(OMe)(6)] (2), [Co(dpa)(acac)(2)](2)[V6O(3)(OMe)(6)](2)MeOH (3), [Co(phen)(acac)(2)](2)[V6O13(OMe)(6)] (4), [Cu(dpa) (acac)],[Viv(2)Vv(4)O(12)(OMe)(7)] (5), and [Cu(dpa)(acac)(MeOH)](2)[(V2V4O11)-V-IV(OMe)(8)] (6) (POV = polyoxovanadate; dpa = 2,2'-dipyridine amine; phen = 1,10-phenanthroline; acac = acetylacetone anion) have been synthesized by controlling the reaction conditions and characterized by single-crystal X-ray diffraction and powder X-ray diffraction analyses, FT-IR spectroscopy, element analyses, and X-ray photoelectron spectroscopy. In compounds 1-4 and 6, Cu or.Co complexes and alkoxohexavanadate anions are assembled through electrostatic interactions. Differently, in compound 5, seven-methoxo-substituted Lindqvist-type [V6O12(OMe)(7)](2)(-) are bridged to Cu complex via terminal O atoms by coordination bonds. All compounds 1-6 exhibit excellent heterogeneous catalytic performance in oxidative desulfurization and CEES ((2-chloroethyl) ethyl sulfide, a sulfur mustard simulant) abatement with H2O2 as oxidant. Among them, the catalytic activity of 6 [cony. of DBT (dibenzothiophene) up to 100% in 6 h; cony. of CEES reached 100% and selectivity of CEESO ((2-chloroethyl) ethyl sulfoxide) up to 85% after 4 h] outperforms others and can be reused without losing its activity.