Cation molar ratios

The intercalant solution was prepared by titration of an Al3+/ Fe3+cationic solution with 0.2 molL"1 NaOH. The cationic solution contained 0.18 and 0.02 molL"1 of A1C13 and FeCl3, respectively. The NaOH solution was slowly added to the cationic solution at 70°C until the OH/cation molar ratio was equal to 1.9. The intercalant solution was added to the clay suspension under stirring. The final ( Al+Fe) /clay ratio was equal to 3.8 mmol/g of dry clay. After aging for 24h, the pillared clay precursor was washed until total elimination of chloride ions, dried at 60°C and finally calcined at 500°C for 5h. The resulting material is (Al-Fe)PILC. 

Ligand Metal cation Molar ratio, ligand/eatlon Composition of complex Ethanol of solvation, % Alcohol- % Hydrox- molecules ate ide adduct per cation ... 

Table IV. Comparison between cation molar ratios in the reaction magmas and in the crystallized cancrinites...

The initial approach to platinum surface thermodynamics was based on mercury-like double layer experience. In particular the adsorption of H ions was treated as purely electrostatic, which means the complete replacement of these ions by any other cations when the latter are in large excess. This assumption works when H cation molar ratio is below 0.1, and valid at least for pH < 3... 

Reed (1990) also found that molar values of Al/Si, Al/Na, and Al/K in solution were higher than stoichiometric values in feldspar. Al-favored ratios may be produced by either incongruent dissolution of feldspars producing an Al-poor leached layer, as was observed by Shotyk (1990), or by congruent dissolution followed by precipitation of Al-poor secondary minerals containing Si, Na, and K. Because no such phases were observed, Reed (1990) concluded that the elevated Al/cation molar ratios were due to preferential formation of Al-oxalate complexes. 

In all of the phases for which structure refinements have been performed, with but two exceptions, the cations are at least partially ordered. Where the cation molar ratios are 1 6, as in UYeO or NbSceOnF (Rossell, 1976) complete cationic order exists, with the smaller cation on the special octahedral site. Where the cation ratio is not 1 6, as in M3 R4 Oi2, one of the small ions occupies the special site and the remaining and R ions are randomly distributed on the general site. The only phases for which complete cationic disorder has been observed are Zr3Sc40i2 (Thomber et al., 1968) and a high-temperature form of Zr3Yb40i2 (Thomber and Bevan, 1970). A partially-ordered form of Zr3Yb40i2 was also reported by Thomber and Bevan (1970) and the... 

When usiag HF TaF ia a flow system for alkylation of excess ethane with ethylene (ia a 9 1 molar ratio), only / -butane was obtained isobutane was not detectable even by gas chromatography (72). Only direct O -alkylation can account for these results. If the ethyl cation alkylated ethylene, the reaction would proceed through butyl cations, inevitably lea ding also to the formation of isobutane (through /-butyl cation). 

Dissolution of Calculi Model. Dissolved Ions from Ca3(PCf)2. Dissolution of calcium phosphate by macrocyclic polyamines proceeds at pH 7, which is established by measuring the freed cation concentration as well as the freed anion concentration with respect to the control values (Table 7). The molar ratio of [Ca2 + ] to [P04 ]... 

Delaire et al. [124] have reported that laser photolysis of an acidic solution (pH 2.8) containing PMAvDPA (23) and MV2 + allows the formation of surprisingly long-lived MV + - and DPA cation radicals with a very high charge escape quantum yield. The content of the DPA chromophores in PMAvDPA is as low as less than 1/1000 in the molar ratio DPA/MAA. Figure 20 shows a decay profile of the transient absorption due to MV + monitored at 610 nm [124]. The absorption persists for several milliseconds. As depicted in Fig. 20, the decay obeys second-order kinetics, which yields kb = 3.5 x 10s M 1 s. From the initial optical density measured at 610 nm, the quantum yield for charge escape was estimated to be 0.72 at 0.2 M MV2 +. ... 

It is expected, therefore, that the cyclic hexamer also exhibits a characteristic tendency to complex with cations. In fact, the addition of an acetonitrile solution of metal thiocyanates to a solution of the cyclic hexamer in the same solvent shifted the carbonyl absorption to a lower wave number46,52 The shift values depended upon the kind of metal ions present, and the largest shift value of 40 cm-1 was observed for barium thiocyanate (molar ratio of Ba2+/hexamer = 10). In addition to the shift of the carbonyl absorption, the intensities of the C—O-C stretching vibrations around 1200 cm-1 varied appreciably. 

The defects of the matrix play an important role on luminescent performances in these materials. Taking into consideration the preparation process of these compounds with the solid-state reaction of mixtures of BaC03, H3BO3, and NH4H2PO4 at different molar ratio, non-equal evaporation during the sintering process of these powders is inevitable and thus results in the formation of intrinsic defects, such as cation and oxygen vacancies. Positional disorder of B and Vacant B (Vb)" have been reported in SrBPOs crystals on the basis of... 

In an ideal pure preparation of Na,K-ATPase from outer renal medulla, the al subunit forms 65 70% of the total protein and the molar ratio of a to is 1 1, corresponding to a mass ratio of about 3 1 [1,5]. Functionally the preparation should be fully active in the sense that each a/ unit binds ATP, Pj, cations and the inhibitors vanadate and ouabain. The molecular activity should be close to a maximum value of 7 000-8 000 Pj/min. The highest reported binding capacities for ATP and phosphate are in the range 5-6 nmol/mg protein and close to one ligand per otjS unit [29], when fractions with maximum specific activities of Na,K-ATPase [40 50 pmo Pj/min mg protein) are selected for assay. 

Atomic ratio alkaline cation/central atom (P or Si). Molar ratio precipitate HPA/initial HPA. deduced from acidimetric titration of the mother solutions. 

Poly(dG-dC) poly(dG-dC) and its methylated analogue structures assume left-handed conformation (Z-DNA) in high molar sodium salt (Na", K" ), in low molar divalent cations (Ca", Mg", Ni ), micromolar concentrations of hexaamine cobalt chloride (Co(NH3)6)Cl3 and in millimolar concentrations of polyamines. In order to analyse the binding of berberine to Z-form DNA, Kumar et al. [186] reported that the Z-DNA structure of poly(dG-dC) poly(dG-dC) prepared in either a high salt concentration (4.0 M) or in 40 mM (Co(NH3)6)Cl3 remained invariant in the presence of berberine up to a nucleotide phosphate/alkaloid molar ratio of 0.8 and suggested that berberine neither bormd to Z-form DNA nor converted the Z-DNA to the... 

Bidentate ligand transfer also occurs between di- and mononuclear complexes via donor-acceptor intermediates. Reactions of the cationic complex [Au2(/i-dppm)2]2+ with [AuX2] (X = C1, Br) salts lead to tri- or dinuclear derivatives depending on the molar ratio (1 1 or 1 2) (Scheme 36).2645... 

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