Four unprecedented V_(14)clusters as highly efficient heterogeneous catalyst for CO_(2)fixation with epoxides and oxidation of sulfides

Chemical fixation of carbon dioxide(CO_(2))is an energy-saving method for alleviating the greenhouse gas emissions,whereas it persists a challenge posed by the demand for efficient catalysts.Herein,four unprecedented examples of tetradecanuclear vanadium clusters,namely,[(C_(2)H_(8)N_(2))6(CH_(3)O)8(CH_(3)OH)_(2)V_(10)^(Ⅳ)V_(4)ⅤO_(26)](V_(14)-1),[(C_(3)H_(10)N_(2))_(6)(CH_(3)O)_(8)(CH_(3)OH)_(2)V_(10)^(Ⅳ)V_(4)ⅤO_(26)](V14^(-2)),[(C_(6)H_(14)N_(2))6(CH_(3)O)8(CH_(3)OH)_(2)V_(10)^(Ⅳ)V_(4)ⅤO_(26)]·5H_(2)O(V14^(-3))and[(C_(4)H_(12)N_(2)O)_(4)(C_(4)H_(11)N_(2)O)_(2)(CH_(3)O)_(2)V_(10)^(Ⅳ)V_(4)ⅤO_(28)]·6H_(2)O(V_(14)-4),have been triumphantly designed and constructed under solvothermal conditions.Among them,compounds V_(14)-1–4 are the first cases of tetradecanuclear vanadium clusters without the introduction of inorganic acid radical ions.Two main units[V_(10)^(Ⅳ)V_(4)ⅤO_(26)]8+and[V10ⅣV4ⅤO28]4+represent brand-new configurations of tetradecanuclear vanadium clusters.Given the fact that the presence of V^(Ⅳ)/V^(Ⅴ)can potentially facilitate electron transfer and consequently expedite catalytic reactions,we explored the catalytic activities of these compounds.Remarkably,V_(14)-1 was further used as a heterogeneous catalyst in the CO_(2)fixation into cyclic carbonates under milder conditions(60℃,0.5 MPa)and exhibited higher catalytic activity.Also,the experimental results indicated that V_(14)-1 could efficiently catalyze the sulfoxidation,which could fully convert most sulfides within 40 min at room temperature.Moreover,as a stable heterogeneous catalyst employed in CO_(2)fixation with epoxides and oxidation of sulfides,V_(14)-1 could be consecutively used multiple cycles without losing its catalytic activity.