Syntheses and structure of three 2D polyoxometalates derived from macrocation [Cr _3O(COOH) _6(H _2O) _3] ~+ and α-Keggin-type polyoxomolybdate anions

摘要

Three novel organic-inorganic hybrid compounds with 2D infinitely extended structure, K _3[Cr _3O(COOH) _6(H _2O) _3][SiMo _(12)O _(40)]·8.5H _2O (1), K _3[Cr _3O(COOH) _6(H _2O) _3][GeMo _(12)O _(40)]·9H _2O (2) and K 2[Cr 3O(COOH) 6(H 2O) 3][PMo 12O 40]·10.25H 2O (3), were synthesized by reaction of Keggin-type polyoxomolybdates with a macrocation of [Cr _3O(COOH) _6(H _2O) _3] ~+ and further characterized by elemental analyses, IR, UV-Vis spectroscopy, single crystal X-ray structural analyses, thermogravimetric and electrochemical properties, which were constructed from saturated Keggin-type polyoxomolybdates and trinuclear chromium formate macrocations. Single crystal X-ray structural analyses of 1, 2 and 3 reveal that polyoxomolybdate anions [XMo _(12)O _(40)] ~(n-) (X = Si ~(IV), n = 4; X = Ge ~(IV), n = 4, X = P ~V, n = 3) and macrocations [Cr _3O(COOH) _6(H _2O) _3] ~+ are polymerized through the bridging K ~+ cations to form a 2D infinitely extended layer structure with honeycomb-like apertures.