Complex/metal ratio

It is quite possible that the mechanism will change in the course of the deposition. As the metal is depleted from solution, the complex metal ratio will increase... 

Bismuth trioxide forms numerous, complex, mixed oxides of varying composition when fused with CaO, SrO, BaO, and PbO. If high purity bismuth, lead, and copper oxides and strontium and calcium carbonates are mixed together with metal ratios Bi Pb Sn Ca Cu = 1.9 0.4 2 2 3 or 1.95 0.6 2 2 3 and calcined at 800—835°C, the resulting materials have the nominal composition Bi PbQ4Sr2Ca2Cu20 and Bi 25PbQgSr2Ca2Cu20 and become superconducting at about 110 K (25). 

In the latter function, the reagent behaves as a surfactant and forms a cationic micelle at a concentration above the critical micelle concentration (1 x 10 4M for CTMB). The complexation reactions occurring on the surface of the micelles differ from those in simple aqueous solution and result in the formation of a complex of higher ligand to metal ratio than in the simple aqueous system this effect is usually accompanied by a substantial increase in molar absorptivity of the metal complex. 

The complexation of other mixed oxa aza macrocycles has been studied, and protonation and stability constants of the zinc complexes of macrocycles l,4,10,13-tetraoxa-7,16-diazacycloocta-decane-7,16-bis(malonate), the -7-malonate derivative and -7,16-bis(methylacetate) derivative have been determined by potentiometry at a 1 1 ligand-to-metal ratio.730... 

The metal vapor reaction products differed from traditional organolanthanide complexes in many ways. First, the observed stoichiometries had low ligand to metal ratios. For example, the ytterbium and samarium 3-hexyne products (Reaction 4) had formal ligand to metal ratios of one, whereas most organolanthanides are commonly nine or ten coordinate (6-10). Second, the stoichiometries varied in an... 

The synthetic principles underlying the preparation of the 1 1 carbene complexes (above) are also applicable to products with a 2 1 ligand/metal ratio . The carbene components may be introduced as free carbenes or their dimers, or generated in situ from the onium salts. A second major pathway uses anionic hetero-... 

No catalyst has an infinite lifetime. The accepted view of a catalytic cycle is that it proceeds via a series of reactive species, be they transient transition state type structures or relatively more stable intermediates. Reaction of such intermediates with either excess ligand or substrate can give rise to very stable complexes that are kinetically incompetent of sustaining catalysis. The textbook example of this is triphenylphosphine modified rhodium hydroformylation, where a plot of activity versus ligand metal ratio shows the classical volcano plot whereby activity reaches a peak at a certain ratio but then falls off rapidly in the presence of excess phosphine, see Figure... 

The bioaffinity parameter a basically reflects the free metal ion concentration, whereas the limiting flux ratio b reflects the total labile metal species concentration. Due to the complexation, the ratio a/b thus changes by a factor (1 +sKcl) in spherical geometry, while the factor (1 I sKc ) (l I Kc ) is required for planar geometry [26]. 

Garces, J. L., Mas, F., Cecilia, J., Puy, J., Galceran, J. and Salvador, J. (2000). Voltammetry of heterogeneous labile metal-macromolecular systems for any ligand-to-metal ratio. Part I. Approximate voltammetric expressions for the limiting current to obtain complexation information, J. Electroanal. Chem., 484, 107-119. 

Fig. 10. NMRD curves of free Gd (O) and its complexes with calix[4]arenes2(0) (at the maximum of the relaxivity titration curve), 3 ( ) (at the maximum of the relaxivity titration curve), 4 (A) (ligand to metal ratio = 2) in anhydrous acetonitrile at 25° C (63,66,67).

From these studies of aryllithium complexes, it can further be concluded that the quadrupolar interaction is a very sensitive indicator of the type of aggregation and solvation state. In certain cases the /-value ranges overlap, but additional investigations can often easily clarify the ambiguity, such as the ligand/metal ratio. The latter can, for example, be determined by a solution H NMR spectrum of the solid material in a suitable solvent. 

Greater ratios up to H M = 4.5, for example in BaReHg, have been found [43] however, all hydrides with a hydrogen to metal ratio of more than 2 are ionic or covalent compounds and belong to the complex hydrides. 

More than 50 macrocyclic crown ethers were synthesised by Pedersen, and many were found to solublise alkali metal salts in non-polar solvents. He isolated 1 1 complexes with metal salts (87) and also showed that if the cation was too large to fit in the central hole, complexes with ratios of 1 2 or 2 3 (metal ether) could be obtained (88). Some of the larger ethers have been shown to complex two metal atoms simultaneously (89). Stability constants in solution are affected by the nature of the anion and the solvent. Both are also important in obtaining crystalline products. 

Comparable results are known for the decomposition of nickela-cyclopentane complexes wMch lead, depending on the ligand-to-metal ratio to cyclobutane, 1-butene and ethylene... 

The divergent synthetic approach is schematically summarized in Figure 7. Reaction of the mononuclear complex-ligand tRu(2,3-dpp)j] with the complex-metal [Ru(2,3-Medpp)2Cl2] in a 1 3 molecular ratio leads to a tetranuclear complex (first dendrimer generation) which in its peiipheiy contains six protected chelating sites. Demethylation of this species restores its ligand ability and yields... 

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