New Complex Sulfides of the Va-metals: Preparation and Crystal Structure of Na3VS4 (with a note on the crystal structure of the low temperature modification of Na3PO4)

Columnar, purple crystals of Na3VS4 were obtained from the melt. Na3VS4 is tetragonal, tP64, s.g. P`421c (No. 114), Z=8 with a=13.502(1)Ä, c=7.9504(8)Ä. The crystal structure was determined from diffractiometer data and refined to a conventional R of 0.017 (746 Fo's, 75 variables). Na3VS4 crystallizes with a new structure type. The crystal structure is characterized by discrete tetrahedral complex anions [VS4](3-) which are close to Td-symmetry and are connected by two Na(+)-cations to form fourfold groups. The average V-S-bond length is 2.153(1)Ä. The crystal structure contains four crystallographically independent Na(+)-cations in irregular sulfur coordinations. The crystal structure is closely related to that of the low temperature modification of Na3PO4 reported recently.