Abstract: In order to investigate the types of compounds of arylarsenic polymo-lybdates, we have prepared ortho-, meta-, para-nitrophenylarsenic acids and tested the reactions of these acids with sodium molybdate at pH3～5. Five new salts of arylarsenic polymolybdates have been synthesized and characterized, (a) (CN₃H₆)₅ [(o-NO₂C₆H₄As)₂Mo₆O₂₅H]·H₂O, (6) Cs₅[(o-NO₂C₆H₄As)₂Mo₆O₂₅H], (c) (CN₃H₆)₅ [(m-NO₂C₆H₄As)₂Mo₆O₂₅H]·4H₂O, (d) (CN₃H₆)₅ [(p-NO₂C₆H₄As)₂Mo₆O₂₅H]·4H₂O, (e) Cs₅[(p-NO₂C₆H₄As)₂Mo₆O₂₅H].We thus find that different positions of nitro group on benzene ring have little influence on the complex type thus formed.They all belong to [(RAs)₂Mo₆O₂₅H]^5- type, which is different from the [(RAs)₂Mo₆O₂₄]4- type reported by Kwak et al, but is the same as its phenyl derivative type [(RAs)₂Mo₆O₂₅H]^5-and also the same as its tungsten congener type [(RAs)₂W₆O₂₅H]^5- reported by Wasfi et al,The infrared spectra, ultraviolet spectra and cyclic voltammograms of all these salts have been reported. The infrared spectroscopic and electrochemical anomaly of ortho-nitrophenylarsenic polymolybdates has been discussed .

Key words: Nitrophenylarsenic acids, Polymolybdates