Studies on organo‐phosphonis, ‐arsenic and ‐antimony polytungstates and polymolybdates: II. Degradation method for preparing arylarsenic polytungstates

Six guanidinium salts of arylarsenic po1ytungstates have been prepared by the "degradation method" using sodium metatungstate as a starting material instead of sodium tungstate, They belong to three types of complexes: [(RAs)_2W_6O_(25)H]~(5-) where R=C_6H_5(1),o-NO_2C_6H_4(2),m-NO_2C_6H_4(3), p-NO_2C_6H_4(4),[(RAs)_2W_6O_(25)]~(4-) where R=p-NH_2C_6H_4(5), and[(RAs)_2W_6O(25)]~(6-)where R=3,4,-C_6H_3 (NO_2)(OH)(6). Complex 1 is a known compound, prepared by the acidification building up method, i.e. conversion of sodium tungstate to polytungstate. Complex 1 and 6 prepared by the degradation method, i.e. from sodium metatungstate to lower polytungstate, are briefly reported in our previous re- port of this investigation. Complexes 2-5 are new compounds. Molecular structures of complexes 5 and 6 have been determined by means of single-crystal X-ray diffraction studies. It is especially em- phasized that the degradation method starting with metatungstate has the advantage in the simplification of reaction products. thus leading to their higher yields.