Facile Synthesis of Zero-, One-, and Two-Dimensional Vanadyl Pyrophosphates

Crystallization of Na2VOP2O7 from its aqueous solution results in formation of a one-dimensional inorganic polymer {Na2VO(H2O)P2O7·7H2O}n (1). When this polymer is dehydrated at elevated temperatures this polymer undergoes a phase transition to form the two-dimensional framework β-Na2VOP2O7, which although previously reported had been difficult to access. Exchanging lithium for sodium via ion-exchange chromatography results in formation of a discrete, cyclic, tetramer species, Li8[VOP2O7(H2O)·4H2O]4 (2). Isolation of crystalline β-Li2VOP2O7 using a dehydration procedure analogous to the one employed for the sodium derivative was unsuccessful. In contrast, we show that β-K2VOP2O7 can be obtained from the amorphous phase K2VOP2O7·nH2O (n = 0–7) upon thermal dehydration.