A new hybrid framework based on a 'superoctahedral' [V_7O_6F_(30)]~(14-) polyanion

摘要

Solvothermal synthesis has led to the isolation of an unusual hybrid framework solid [CH_3NH_3]_8[Cu(Py_)4]_3]V_7O_6F_(30)] in which the novel [V_7O_6F_(30)]~(14-) polyanion is linked via [Cu(py)_4]~(2+) moieties into a doubly interpenetrated cubic lattice. There is an increasing tendency in solid state chemistry towards the use of 'molecular' building blocks in the construction of extended framework materials, which may consequently exhibit 'extended' physical properties such as porosity, magnetic, electronic, optical activity or other features. Several examples of this modular approach to building new solids occur in polyoxometalate chemistry, where poly-oxomolybdate or polyoxovanadate units are linked together, for example, by Ag(I) cations, Cu-bipy moieties, [Zn(H_2O)_4]~(2+) groups or lanthanide complexes. We have recently been exploring solvothermal vanadium oxyfluoride (VOF) chemistry, and have shown the existence of a rich variety of oligomeric, anionic VOF species. We have also shown that, with judicious choice of counter-cation and synthetic conditions, particular VOF units may be crystallised in polar, optically-active arrays or condensed into extended chain or ladder-like networks of magnetic interest.