Molybdate, hydration

At higher acidification (H /Mo>2), soluble polycations are formed without the formation of solid pha.scs [78,791. The molybdic hydrates obtained in strong acid media are described below. Upon the addition of a base, the.se com x>unds decompose rapidly to form the [Mo04] monomer. 

The difference in behavior between tungstic and molybdic hydrates and oxides probably stems from a difference in the tt interactions in the W-0 and Mo-0 bonds [46,90]. 

The carbonates, sulfates, nitrates, and haUdes of lead (except the yeUow iodide) are colodess. Bivalent lead forms a soluble nitrate, chlorate, and acetate a slightly soluble chloride and an insoluble sulfate, carbonate, chromate, phosphate, molybdate, and sulfide. Highly crystalline basic lead salts of both anhydrous and hydrated types are readily formed. Tetrabasic lead sulfate [52732-72-6] 4PbO PbSO, and the hydrated tribasic salt [12397-06-7] ... 

Of the many molybdenum sulfides which have been reported, only MoS, M0S2 and M02S3 are well established. A hydrated form of the trisulfide of somewhat variable composition is precipitated from aqueous molybdate solutions by H2S in classical analytical separations of molybdenum, but it is best prepared by thermal decomposition of the thiomolybdate, (NH4)2MoS4. MoS is formed by heating the calculated amounts of Mo and S in an evacuated tube. The black M0S2, however, is the most stable sulfide and, besides being the principal ore of Mo,... 

Figures 11(a) and 11(b) [112] show the variation of Ni-Ge-P deposition rate and Ge content as a function of aspartic acid and Ge(IV) concentration, respectively. A relatively low P content, ca. 1-2 at%, was observed in the case of films exhibiting a high concentration of Ge (> 18 at%). Like other members of its class, which includes molybdate and tungstate, Ge(IY) behaves a soft base according to the hard and soft acids and bases theory (HSAB) originated by Pearson [113, 114], capable of strong adsorption, or displaying inhibitor-like behavior, on soft acid metal surfaces. In weakly acidic solution, uncomplexed Ge(IV) most probably exists as the hydrated oxide, or Ge(OH)4, which, due to acid-base reactions, may be more accurately represented as [Gc(OH)4 nO ] ".

Instead of aluminum oxide hydrated Zr02 can be used to adsorb irradiated molybdate. Tc is eluted with 2 M HNO3 . 

Normal isopoly- and peroxymolydates of ammonium and several metals are known. The normal or orthomolybdates may be considered as salts of molybdic acid having formulas H2Mo04 xH20 or M20 Mo03 xH20. They are either of monoclinic or scheelite type crystal structure and obtained as hydrated salts. 

A brown-black suspension of M0O2 in hydrate form may be obtained by reducing a solution of ammonium molybdate with hydrogen in the presence of colloidal palladium. 

L = dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), and triphenylphos-phine oxide (OPPh3). The former illustrates how simple polyethers may stabilize the hydrated dioxomolybdenum(VI) bromide core. The others are representative examples of addition compounds with ligands that are able to displace water from the coordination sphere of molybdenum but at the same time are not sufficiently basic toward the proton to cause formation of hydrobromides and molybdates. 

C60H402M0132N42O504 —3OOFI2O, Molybdate, polyoxo-, spherical cluster with acetate ion, hydrate, 34 191... 

H372M0132N42O504P30 -300H20, Molybdate, polyoxo-, spherical cluster with hypopho-sphite ion, hydrate, 34 196 H402C6qMoi32N42O504 - 300H2O, Molybdate, polyoxo-, spherical cluster with acetate ion, hydrate, 34 191... 

Cobalt(II), [triaconta-/j-cyano octakis(tri-methanolcobalt(II)) hexakis(hexacyano-molybdate(V)) -], hydrate, methanolate, 34 159... 

Na2C2s0240sio, Osmate(2-), carbidotetracosa-carbonyldeca-, sodium, 34 221 Na6C10i9P2RhS6C37H24, Rhodate(6-), trans-carbonylchlorobis(tris(3-sulfonatophenyl)-phosphine)-, sodium, 34 124 Nai5Hi52Moi53O528.5 400H2O, Molybdate, polyoxo-, wheel-shaped cluster, hydrate, 34 197... 

Molybdic and Tungstic Acids. What hydrates do molybdenum and tungsten trioxides form ... 

Aqueous solutions of molybdate and arsenate, pH 3-5, contain [AsMo903i(H20)3]3 and an As2Mo6 anion.71 The exact structure of the latter ion in solution is in some doubt, although the tetramethylammonium sodium salt contains the anion shown in Figure 15. Low angle X-ray scattering measurements of aqueous molybdoarsenate solutions are not compatible with this structure and the anion may be hydrated in a fashion similar to that observed for the analogous... 

When selenic acid and molybdic acid are heated together on a water-bath for several days a compound of composition Mo03.Se03 is formed, which is obtainable as a crystalline mass,4 and which with a little water yields a hydrate, having the formula Mo03.Se03.2H20 when dried at 110° C. This compound has the properties of a tetrabasic acid. 

---