Hydrothermal synthesis of molecular oxovanadium compounds. The crystal and molecular structures of [VO2(terpy)]NO3, [VO(terpy)(OH3PC6H5)2], [{Cu(H2O)(terpy)}V2O6], [{Cu(ttbterpy)}V2O6] and [{Cu(ttbterpy)}VO2(HO3PCH2PO3)] · H2O (terpy = 2,2′:6′,2″-terpyrid

Hydrothermal conditions have been exploited in the syntheses of five molecular oxovanadium species [VO2(terpy)]NO3 · H2O (1 · H2O), [VO(terpy)(HO3PC6H5)2] (2), [{Cu(H2O)(terpy)}V2O6] · H2O (3 · H2O), [{Cu(ttbterpy)}V2O6] · 2H2O (4 · 2H2O), and [{Cu(ttbterpy)}VO2(HO3PCH2PO3)] · H2O (5 · H2O). The binuclear molecular cation of compound 1 exhibits a planar {V2O4}2+ core from the fusion of two cis-oxovanadium(V) units. Compound 2 is a six coordinate V(IV) species with {VO3N3} coordination geometry. Compounds 3 and 4 are constructed from the common {V4O12}4− cluster with peripheral Cu(II)–ligand subunits. The Cu(II) square pyramids of the [{Cu(H2O)(terpy)}2V4O12] cluster of 3 share a single vertex with the vanadate cluster as a consequence of coordination of an aqua ligand. In contrast, in [{Cu(ttbterpy)}2V4O12] (4), each Cu(II) square pyramid shares two vertices with the vanadate core. Of the materials of this study, only compound 5 incorporates both Cu(II) and diphosphonate into the final product. The structure of the dimer consists of a cyclic {V2P2O4} core linked through diphosphonate ligands to two peripheral {Cu(ttbterpy)}2+ units.

Graphical abstractHydrothermal reactions of Na3VO4 and terpyridine or terpyridine derivatives, in the presence of Cu(II) and diphosphonic acids, yield a variety of molecular species. The structure of [{Cu(ttbterpy)}VO2(HO3PCH2PO3)] · H2O is shown.Figure optionsDownload full-size imageDownload as PowerPoint slide