A one-dimensional selenotungstate based on neodymium and {SeO3} groups for catalytic synthesis of imidazoles

Abstract

A novel neodymium-{SeO₃}-bridged selenotungstate, [Na₁₆Nd_2.5(SeO₃)(SeO₃)(mal)(W₄O₉)(SeW₈O₃₂)(SeW₉O₃₃)₂(H₂O)₄]·ca.26H₂O (NdSeW, mal = malic acid), has been successfully synthesized and structurally characterized. This compound is constructed from both {SeW₉} and {SeW₈} building units, which are linked through an organometallic {Nd₂Se₂(mal)W₄} cluster, forming a distinctive triangular arrangement. Two triangular trimers are connected via Nd–O–W to form a hexameric unit, which is subsequently extended into a one-dimensional chain structure through bridging by two {SeO₃} groups. This type of one-dimensional chain architecture, constructed through alternating connections involving neodymium and {SeO₃} groups, is extremely rare in polyoxometalate chemistry. In addition, NdSeW exhibits excellent catalytic activity for the synthesis of 2,4,5-trisubstituted imidazoles through the three-component condensation of aldehydes, benzils, and ammonium acetate under environmentally benign conditions.