Structure and Properties of a Novel 3D Straight-Channel Polyoxovanadate and an Unexpected Trimeric Barbiturate Obtained by Hydrothermal Reactions

The hydrothermal reaction of NaVO3·H2O, barbituric acid, NH2NH2·2HCl, H3PO4, and H2O gave a novel
heteropolyoxovanadate Na6[(PVO4)VV6VIV12O39]2·H3PO4·31H2O (1) and an unexpected phase Na2[C12H6N6O9]·7H2O
(2). The basic building blocks in 1 are the six-capped sphere-shaped heteropoly anion [(PVO4)VV6VIV12O39]3- with
framework similar to that of the reported polyoxovanadates possessing {V18O42} clusters encapsulating VO4 or
other ions. These heterpoly anionic units are linked via V−O−V bridges into an interesting 3D straight-channel
structure. The structure of 2 consists of novel organic anions ([C12H6N6O9]2-, 5,5-bis(2‘,4‘,6‘-trioxopyrimidyl)barbital,
representing the first oxidized barbituric acid trimer) linked via sodium ions into 1D hollow tubes with diameter of
4.49 × 6.86 Å and further connected into a three-dimensional framework via hydrogen bonds.