Synthesis and structural characterization of N-(para-substituted-phenyl)aza-15-crown-5 sodium heteropolymolybdotungstate

The title complexes of [Na(N-(p-Rph)15C5) (Et2O)](2)Na2WxMo8-xO26 [(1): R = H, x = 0.26: (2): R = CH3, x = 0.50] were synthesized by the reaction of N-(p-Rph)15-crown-5 with tetra-n-butylammonium polymolybdotungstate and a sodium cation and characterized by elemental analysis, IR, H-1 NMR and H,H-COSY NMR spectra and crystal structure determination of complex (2). The complexes can be described as having a two-dimensional [Na2WxMo8-xO26](infinity)(2-) anion framework in which the sodium is coordinated with six terminal O atoms of neighbouring beta-octamolybdotungstates in octahedral geometry and a [Na(N-(p-Rph)15C5(Et2O)](+) complex cation in which the sodium cation shows pentahedral pyramidal coordination geometry, which is rarely observed. The packing of the complex cations and the two-dimensional anion framework were in different layers separately. The N-(para-substituted-phenyl)aza-15-crown-5 combined with the octamolybdotungstate anion with a ratio of W/Mo of 0.26/7.74 in complex (1) and 0.50/7.50 in complex (2), respectively, however the DB18C6 and DB24C8 chose the hexamolybdotungstate anion with a ratio of W/Mo of 4/2 and 1/5 to form the complexes [Na(DB18C6) (CH3OH)](2)W4Mo2O19 and [Na(DB24C8)](2)W1Mo5O19. (C) 1997 Elsevier Science Ltd.