Gallophosphonates containing alkali metal ions.: 2.: Synthesis and structure of gallophosphonates incorporating Na+ and K+ ions

The reactions between t-BuP(O)(OH)(2) and equimolar quantities of MGaMe4(M = Na, K) yield ionic and alkali metal containing molecular gallophosphonates [Na-4(mu(2)-OH2)(2)(THF)(2)][(Me2GaO3PBu-t)(2)](2) . 2THF(2) and [K(THF)(6)][K-5(THF)(2){(Me2GaO3PBu-t)(2)}(3)] (3), respectively. Compounds 2 and 3 are soluble in common organic solvents and have been characterized by means of analytical and spectroscopic techniques, as well as by single-crystal X-ray diffraction studies. These compounds represent the rare examples of molecular ionic phosphonate cages which contain coordinated Na+ or K+ ions. Compound 2 is constructed from-two eight-membered Ga2O4P2 gallium phosphonate rings which sandwich a central Na-4(H2O)(2) unit. In the case of 3, three eight-membered Ga2O4P2 gallium phosphonate units envelope an aggregated K-5 core which exists in the form of a trigonal bipyramidal polyhedron. The Na+ and K+ ions in 2 and 3 are also coordinated by the endocyclic oxygen atoms of the eight-membered gallophosphonate crowns, apart from the regular exocyclic P-O coordination. Unlike the lithium gallophosphonate [Li-4(THF)(4)][{(MeGaO3PBu-t)(3)(mu(3)-O-2)}(2)] (1), compounds 2 and 5 do not undergo any clean cage conversion reaction in the, presence of 15-crown-5 and 18-crown-6, respectively.