Complexes selenato

A number of basic oxalates, such as (U02)2C204(0H)2-2H20, and salts of basic oxalato complex ions of the types M3UO QO fOH) and Ms(U02)2(C204)4(0H) have also been reported, as well as salts of a wide range of peroxo-, halogeno-, sulfito-, sulfato-, selenito-, selenato-, thiocyanato- and carbonato-oxalato complex anions all need further investigation. 

Figure 1 Structure of the triply selenato-bridged complex (f)7-C7H7)Mo(u2-SePh)3 Mo(CO)3 (reproduced with permission...

Although it is known that protactinium(V) precipitates from dilute sulfuric acid on the addition of potassium sulfate, the product, believed to be K3Pa0(S04)3, has not been satisfactorily characterized (19, 28, 105). There is obviously scope for further research on the preparation of sulfato (and selenato) complexes of pentavalent protactinium. In addition, tetravalent protactinium sulfates, selenates, and their complexes have not been studied. 

A few derivatives of oxyanions have also been prepared protactinium (V) forms hexanitrato complexes, Pa(N03)e , by reaction of the hexachloro complex with dinitrogen pentoxide, in contrast to niobium and tantalum which, under similar conditions, yield only tetranitrato complexes, M0(N03)4 (35). Neptunium (V) nitrates, NPO2NO3 and Np0(N03)3 have also been reported 71). Protactinium (V) sulfato-and selenato complex acids, H3PaO( 804)3 and H3Pa0(Se04)3, have been obtained from aqueous solution (13), but no fully sulfated or sele-nated species have been recorded. 

Sykes and his co-workers have made a detailed study of the metalion reduction of ju.-amido-/a-(ligand)-bis[tetra-amminecobalt(m)] complexes where ligand = sulphato, selenato, phosphato, oxalato, and... 

The kinetic pattern for aquation of the newly characterized iU-amido-At-selenato-dicobalt complex (11) is similar to that established for its / -amido-A -sulphato-analogue. In both cases the product is (12), and there is strong kinetic evidence for transient intermediates of the type (13). A rate law of the form shown in equation (4) above operates kinetic parameters for aquation of the Ai-amido-jM-selenato-complex are included in Table 6. A preliminary report on the kinetics of aquation of the closely related acetato-complex (14) indicates that the rate law of equation (4) also applies here, but the rate law for aquation of the yU-amido-/ -phosphato-complex (15) is more complicated. 

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