Heteropolytungstates with Transition Metal Ions (Fe, Ni, Zn)

Abstract

The syntheses and results of the physico‐chemical studies on aqueous solutions and in solid state of new heteropolytungstates with one or two metal ions (Fe, Ni, Zn) in the anion are presented. The complexes are of particular structural and synthetic interest. The heteropolytungstates with two different metal ions in the anion are the first complexes of his type studied.

Present General Status of Understanding of Heteropoly Electrolytes and a Tracing of Some Major Highlights in the History of Their Elucidation

“…In 1963, Ripan reinvestigated the system of polytungstocobaltates, arriving at the same conclusions that had been put forward by Baker in 1956, including the misformulation of the dicobalt complexes as 12-tungstates. In 1966, in accordance with the structures proposed by Baker 109 in 1956 for “[Co 2+ Co 2+ W 12 O 42 ] 8- ”, and “[Co 2+ Co 3+ W 12 O 42 ] 7- ” Ripan et al reported the preparation and properties of “[ZnZnW 12 O 42 ] 8- ”, “[Ni 2+ ZnW 12 O 42 ] 8- ”, and “[Ni 2+ Fe 3+ W 12 O 42 ] 7- ” and, in confirmation of Agarwala, the preparation of H 4 [Ni(OH) 6 W 6 O 18 ]. The following year (1967) radioelectrophoresis and radiochromatographic studies as functions of pH confirmed Baker's 1966 conclusions 111 about the chemistry and interrelations of the tungstodicobaltates.…”

“…Ripan made extensive use of conductometric, potentiometric, photometric, and polarographic techniques and combinations thereof. − Ripan originated, developed, and extensively applied the techniques of paper chromatography, paper electrochromatography, and, later, paper radiochromatography for elucidating structures and reaction mechanisms of heteropoly anions. − In 1957 she reviewed the preparations of silicomolybdates − undertook cryometric titrations of the free acids of 12-tungstophosophate, and -silicate, and 12-molybdophosphate and -silicate with NaOH in fused Na 2 SO 4 ·10H 2 O (i.e., saturated Na 2 SO 4 solution).…”

“…Two of the four complexes reported had, like metatungstate, H 2 2+ in place of the central atom, while Co 3+ or Ga 3+ replaced one W in the Keggin-like structure. Subsequently, Weakley and Malik 12,13 and then the Tourne ´s, 14 Ripan and Puscasu, 114 and Fournier, Massart, and Souchay, 115 and many others reported preparations of a large number of 11-tungsto, 17-tungsto, 11molybdo, and 17-molybdo complexes with various central heteroatoms and various lower-valent octahedral metal atoms substituted for a W or Mo in a Keggin or Wells-Dawson structure. 116…”

“…Ripan originated, developed, and extensively applied the techniques of paper chromatography, paper electrochromatography, and, later, paper radiochromatography for elucidating structures and reaction mechanisms of heteropoly anions. [213][214][215][216][217][218][219][220][221][222][223][224][225][226] In 1957 she reviewed the preparations of silicomolybdates. 227 From 1959 to 1961 Ripan et al [228][229][230] undertook cryometric titrations of the free acids of 12-tungstophosophate, and -silicate, and 12-molybdophosphate and -silicate with NaOH in fused Na 2 SO 4 ‚10H 2 O (i.e., saturated Na 2 SO 4 solution).…”