Two Ce-Substituted Selenotungstates Regulated by N, N-Dimethylethanolamine and Dimethylamine Hydrochloride.

Two multi-Ce-substituted selenotungstates (STs), [HDMEA][HN(CH)]HNa[Ce(HO)(DMEA)WO(α-SeWO)]·26HO (1) and [HN(CH)]HNa[CeWO(HO)(α-SeWO)]·63HO (2), were prepared by the one-pot approach of sodium tungstate, sodium selenite, and lanthanide nitrate in an acidic water solution in the presence of N, N-dimethylethanolamine (DMEA) or dimethylamine hydrochloride (DMAHC). 1 was obained in the presence of DMEA, whereas 2 was synthesized in the presence of DMAHC. The trimeric polyoxoanion of 1 contains an unusual V-shaped [SeWO] group embracing a prominent heterometal oxide fragment, [Ce(HO)(DMEA)WO], and the hexameric polyoxoanion of 2 is constructed from two equivalent trimeric [CeWO(HO)(SeWO)] subunits through two -O-W-O-Ce-O- linkages. The most worthy of attention is that the polyoxoanion of 1 can be approximatively viewed as a half of the polyoxoanion of 2 because of the coordination and blocking effect of DMEA. The stability of 1 and 2 in different water pH values was studied by electrospray ionization mass spectroscopy (ESI-MS), and the results manifest that 1 and 2 are stable in pH = 3.5-7.5 and 3.5-7.0, respectively. The oxidation reactions of aromatic sulfides catalyzed by HO were studied when 1 or 2 worked as a catalyst, and experimental results reveal that 1 or 2 can serve as available catalysts for the oxidation of aromatic sulfides under mild conditions.