The antimony(iii)-bridged heteropolyanion sandwich dimers [Sb III3(A-α-XW 9O 34) 2] 11- (X = Si IV, Ge IV) and C-shaped double-sandwich [Sb III6O 2(PW 6O 26)(A-α-PW 9O 34) 2] 15-

Abstract

Interaction of potassium antimony(iii) tartrate hydrate K 2(SbC 4H 2O 6) 2· 3H 2O with the trilacunary Keggin derivatives [A-α-XW 9O 34] 10- (X = Si IV, Ge IV) and [A-α-PW 9O 34] 9- in aqueous acidic medium (pH 4.8) resulted in three novel polyanions, [Sb 3(A-α- XW 9O 34) 2] 11- (X = Si IV (1), Ge IV (2)) and [Sb 6O 2(A-PW 6O 26)(A-α-PW 9O 34) 2] 15- (3), which were isolated as the hydrated potassium salts K 11[Sb 3(A-α-XW 9O 34) 2]·31H 2O (X = Si IV (K-1), Ge IV (K-2)) and the mixed potassium-sodium salt K 14Na[Sb 6O 2(A-PW 6O 26)(A-α-PW 9O 34) 2] ·61H 2O (KNa-3) salts, respectively, and characterized by single-crystal X-ray diffraction, IR spectroscopy, as well as elemental and thermogravimetric analyses. The Sb III-containing polyanions 1-3 possess unique structural features, as they represent the first examples of sandwich-type POMs with trigonal-pyramidal Sb IIIO 3 linkers. The stability of 1-3 in aqueous media was investigated by multinuclear ( 183W, 31P) NMR and UV-Vis spectroscopy. © 2012 The Royal Society of Chemistry.