A novel diniobium-inserted sandwich-type polyoxometalate K6H3[Nb2K(H2O)4(A-α-SiW9O34)2]·23H2O constructed from two trivacant Keggin [A-α-SiW9O34]10− moieties linked via a V-shaped {Nb2K} group

A novel sandwich-type polytungstosilicate K6H3[Nb2K(H2O)4(A-α-SiW9O34)2]·23H2O (1) has been prepared by reaction of K7HNb6O19·13H2O with Na10[A-α-SiW9O34]·23H2O in the presence of H2O2 under acidic medium and structurally characterized by elemental analysis, IR spectra, UV spectra and single-crystal X-ray diffraction. 1 consists of two trivacant Keggin [A-α-SiW9O34]10− moieties linked via a V-shaped {Nb2K} group resulting in a diniobium-inserted sandwich-type structure and represents a novel diniobium-inserted sandwich-type tungstosilicate. The photocatalytic measurement illustrates that 1 can effectively accelerate the photodegradation of rhodamine-B.