Metals stoichiometry

For divalent metals which readily form tetrahedral complexes and for trivalent metals which show a preference for octahedral donor sets, neutral D2EHPA complexes are formed with 4 1 and 6 1 ligand metal stoichiometries respectively,... 

It is common practice to refer to these compounds using numerical acronyms corresponding to the metal stoichiometries. The decoding scheme and Tc values are collected in the following table (13)(21)-(23) the lead-substituted phases are included but not generally referred to with acronyms. 

As a consequence, the selectivity of extraction of first transition series dications does not follow the Irving Williams order when these reagents are used in base metal recovery. The bis(2-ethylhexyl)ester of phosphoric acid (D2EHPA) shows [1] a preference Zn2+ > Cr21 > Mn2+ > Fe2+ > Co2+ > Ni2+ V2+ which is exploited in the recovery of zinc from primary sources. [69] M2+ ions which form tetrahedral complexes and M3+ ions which show a preference for octahedral donor sets give neutral complexes with 4 1 and 6 1 D2EHPA metal stoichiometries respectively,... 

Lanthanide(III) catecholates exhibit a complex coordination chemistry in aqueous solution [154], While at neutral pH, 1 1 complexes are present in solution, higher pH values (pH > 11) favor 2 1, 3 1 and 4 1 catechol metal stoichiometries as shown in Na[Gd(cat)2] 10H2O , Na6[Ln(cat)3]2-20H2O (Ln = Gd, Ho) and Na5[Gd(cat)4] 19.2H20. The latter monogadolinium complex is isomorphous with the cerium(IV) complex (Table 11). The change of the metal charge from Ln(IV) to Ln(III) now requires a fifth sodium cation which is disordered over several sites in the cell. 

Figure 6. Hydrogen uptake for rhodium, platinum and nickel cations as a function of duster size. H/M is the measured hydrogen to metal stoichiometry of the duster.

Spiering MM, Ringe D, Murphy JR, Marietta MA. Metal stoichiometry and functional studies of the diphtheria toxin repressor. Proc. Natl. Acad. Sci. U.S.A. 2003 100 3808-3813. 

The resulting sample showed IR carbonyl spectra (Fig. 34) identical to those of [TMBA]2[Rh4Fe2(CO)i6] in CHjCN solution or deposited on NaY zeolite, whose IR carbonyl absorptions are 2093(s), 2044(w), 1985(w), 1744(m), 1705(s), and 1698(w) cm" Rh K- and Fe K-edge EXAFS studies are under way to unravel their structures and Fe/Rh metal stoichiometries. 

The single site model is used to describe the interactions between the cation and the humic acids (11). Since humic substances are heterogeneous and complex molecules, the ligand is defined as a monodentate site (A) with no particular assumption on its chemical nature. Complexes of 1 1 (metalication) stoichiometry are assumed to be formed according to the equilibrium ... 

FIGURE 9.3 Diagram for the variation of the oxygen/metal stoichiometry with the partial pressure of oxygen for different perovskite-type oxides. (From figure 1 of Girdauskaite et al., 2007. J. Solid State Electrochem. 11, 469-477, with permission.)... 

Furthermore, analysis of the metals content at the surface (top 100 A) shows lower amounts of Cu at the surface compared to the theoretical ratio of Y Ba Cu of 1 2 3. Wavelength dispersive electron microprobe is an extremely sensitive probe of the bulk, rather than surface composition. Data acquired by this technique gave a metals stoichiometry much closer to the expected YBa2Cu307, but now somewhat high in barium and copper,... 

The macrocycle L1 [structure (1)] having an inner ring of 18-member atoms has been synthesized (as its metal complexes) by the use of large metal ions as templates for the [2 + 2] Schiff base condensation of two molecules of 2,6-pyridinedicarboxaldehyde with two molecules of 1,2-benzenediamine.2 The template action of the metal ion is evidenced by the observation that only oils or gums are obtained in metal-free reactions. When the Ba2+ ion (ionic diameter 2.84 A)2 is employed as template, the product complex has a 2 1 ligand metal stoichiometry (Part A), whereas, for the Ca2+, Sr2 or Pb2+ ions (ionic diameter 2.24, 2.52, and 2.58 A, respectively), the products have a 1 1 metal-to-ligand stoichiometry. Smaller metal ions are ineffective as templates for the synthesis of L1. 

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