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

Six alkoxohexavanadate-based Cu- or Co-POVs [Cu(dpa)(acac)(H 2 O)] 2 [V 6 O 13 (OMe) 6 ] ( 1 ), [Cu(phen)(acac)(MeOH)] 2 [V 6 O 13 (OMe) 6 ] ( 2 ), [Co(dpa)(acac) 2 ] 2 [V 6 O 13 (OMe) 6 ]·2MeOH ( 3 ), [Co(phen)(acac) 2 ] 2 [V 6 O 13 (OMe) 6 ] ( 4 ), [Cu(dpa)(acac)] 2 [V IV 2 V V 4 O 12 (OMe) 7 ] ( 5 ), and [Cu(dpa)(acac)(MeOH)] 2 [V IV 2 V V 4 O 11 (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 [V 6 O 12 (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 H 2 O 2 as oxidant. Among them, the catalytic activity of 6 [conv. of DBT (dibenzothiophene) up to 100% in 6 h; conv. 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.