Abstract: In order to investigate the influence of organic groups on the types of organoarsenic polymolybdates, the reations of p-aminophenylarsonic acid with sodium molybdate were tested at pH=3-5. Six salts were prepared and characterized. (1) (CN₃H₈)₄ [(p-NH₃C₆H₄As)₂Mo₆O₂₅]·H₂O, (2) (CN₃H6)₄ [(p-, NH₃C₆H₄As)₂Mo₆O₂₅ ]·6H₂0, (3) Cs₄ [(p-NH₃C₆H₄As)₂Mo₆O₂₅]·4H₂O, (4) C(CH₃)₄N]₄[(p-NH₃C₆H₄As)₂Mo₆O₂₅]·5H₂O, (5) [(n-C₄H₉)₄N]₃Na[(p-NH₃C₆H₄As)₂Mo₆O₂₅]·2H₂O, (6) Ba₂ NH₃C₆H₄As)₂Mo₆O₂₅]·10H₂O. The IR, UV spectra, and electrochemical behavior are reported and discussed. They should belong to the same type as that for phenyl derivative or the nitrophenyl derivatives. But the ammo groups can accept protons, so that the anion' s charge decreases. Very similar to the tungsten congener (CN₃H₆)₄[(p-NH₃C,H₄As)₂W₆O₂₅]·4H₂O, [(RAs)₂Mo₆O₂₅]^4- type of complexes are formed.

Key words: p-Aminophenylarsonic acid, Polymolybdates, Polytungstates