Ligation effects

Selected entries from Methods in Enzymology [vol, page(s)] Aspartate transcarbamylase [assembly effects, 259, 624-625 buffer sensitivity, 259, 625 ligation effects, 259, 625 mutation effects, 259, 626] baseline estimation [effect on parameters, 240, 542-543, 548-549 importance of, 240, 540 polynomial interpolation, 240, 540-541,549, 567 proportional method for, 240, 541-542, 547-548, 567] baseline subtraction and partial molar heat capacity, 259, 151 changes in solvent accessible surface areas, 240, 519-520, 528 characterization of membrane phase transition, 250,... 

Py) < (CN , OH ) < (CN, CN ). A molecular orbital treatment advanced for the elucidation of axial ligation effects on electronic spectra of the corrin complexes (19) may be applied in this case. 

There still remains the question, which is unanswered by either the TT-bonding hypothesis or by the concept of metal polarizing power, as to why cobalt(III) and manganese(I) experience a cooperative ligand effect, whereas there is no evidence as yet for such an effect with chromium in various oxidation states [any Cr(III)—SCN compounds are purely kinetic in origin and thermodynamically unstable with respect to Cr(III)— NCS] with iron(II) or iron(III), cobalt(II), or nickel-(II), even though the stereochemistries of these last two elements may be drastically modified by ligational effects (see Tables XXIX and XXXI). 

The examples discussed above demonstrate the unique advantages of zeolitic hosts primarily stemming from highly dispersed exchange sites and the ligating effect of the framework on the cations. 

Unlike the facile reaction of COD with carbon nucleophiles, alkylation of monoalkenes with palladium(II) salts is most difficult. However, when PdCl2 and 2 equiv of EtsN are employed, stabilized carbanions (p Ta = 10-17) may successfully alkylate monoalkenes (Scheme The ligating effect of Et3N is essential to the success of this reaction. The nature of the product obtained is determined by the reaction conditions. Allowing the reaction to warm to room temperature affords the corresponding alkene, whereas bubbling hydrogen into the reaction mixture at 50 °C results in the formation of a saturated product. ... 

The slope of this curve is then assumed to correspond to ACp according to equation 6. But this procedure is problematic, since the slope of the plot is not only determined by the intrinsic change in heat capacity of the polypeptide chain, but also by ligation effects which include piotonatioii changes [9,22], Furthermore ACp generally cannot be expected to be temperature independent, due to the curvature in the Cp D function and the linearity of Cp,N [23]. 

The search for the racemic form of 15, prepared by allylic cyclopropanation of farnesyl diazoacetate 14, prompted the use of Rh2(OAc)4 for this process. But, instead of 15, addition occurred to the terminal double bond exclusively and in high yield (Eq. 6) [65]. This example initiated studies that have demonstrated the generality of the process [66-68] and its suitability for asymmetric cyclopropanation [69]. Since carbon-hydrogen insertion is in competition with addition, only the most reactive carboxamidate-ligated catalysts effect macrocyclic cyclopropanation [70] (Eq. 7), and CuPF6/bis-oxazoline 28 generally produces the highest level of enantiocontrol. 

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