Ionic complex

Two kinds of tantalum-containing initial solutions were chosen according to their ionic complex structure. The first one contained mostly TaF6 ions (Ta F = 1 18) while the second was characterized predominantly by TaF72 ions (Ta F = 1 6.5). The ionic composition of the solutions was determined by Raman spectroscopy. 

The mixture of products can be separated by dissolving the yellow neutral complex in benzene the red ionic complex is crystallized from chloroform. 

However, the energy difference between N- and S-bonded thiocyanate is very small and is influenced by an interplay of several factors steric effects, solvent and the counter-ion in ionic complexes. To illustrate the last point, in complexes [Pd[Et2N(CH2)2NH(CH2)2NH2]NCS]+, the PFg salt is N-bonded, as it is in the unsolvated BPhg salt. However, though the acetone solvate of the tetraphenylborate is N-bonded, the methanol solvate is S-bonded [126],... 

A highly sensitive method for the determination of anionic surfactants, particularly sodium dodecyl sulfate, has been described [275]. The method is based on the formation of fluorescent ionic complexes of the anionic surfactant with acridine red and acridine yellow. The complexes are extracted with dichloro-... 

In hemoglobin M, histidine F8 (His F8) has been replaced by tyrosine. The iron of HbM forms a tight ionic complex with the phenolate anion of tyrosine that stabilizes the Fc3 form. In a-chain hemoglobin M variants, the R-T equilibrium favors the T state. Oxygen affinity is reduced, and the Bohr effect is absent. P Ghain hemoglobin M variants exhibit R-T switching, and the Bohr effect is therefore present. 

Ionic LCs are interesting systems because they combine the properties of LCs with those of ionic liquids. Although alkali metal soaps were among the first thermotropic LCs to be systematically studied, ionic liquid crystalline derivatives have been reported less frequently than those based on neutral molecular and macromolecular species [39]. When the halide of [AuX(CNR)] complexes is substituted by a second isocyanide, ionic complexes [Au(CNR)2][Y] [R = C6H40C H2 + i (27a),... 

Marcos, M., Ros, M.B., Serrano, J.L., Sola, M.A., Oro, L.A. and Barbera, J. (1990) Liquid-crystal behavior in ionic complexes of silver(I) molecular structure-mesogenic activity relationship. Chemistry of Materials, 2, 748-758. 

A remarkable complex with the composition Co2(R2C fc)5BF4 resulted from an attempt of Hendrickson and Martin (81) to oxidise Co(R2r/tc)3- These authors report diamagnetic, ionic complexes, in which the metal atoms are bridged by two sulfur atoms of the ligands, as is found for Ru2(Et2(irc)5BF4 (77). 

MF Saettone, D Monti, MT Torracca, P Chetoni, B Giannaccini. (1989). Muco-adhesive liquid ophthalmic vehicles—Evaluation of macromolecular ionic complexes of pilocarpine. Drug Dev Ind Pharm 15 2475-2489. 

Among the various intermediate species that may participate in a reaction sequence are stable molecules, ions, free atoms, free radicals, car-banions, carbonium ions, molecular and ionic complexes, and tautomeric or excited forms of stable molecules. If the intermediate is, indeed, a stable substance, then its presence can be detected by any of the standard techniques of chemical analysis, provided that the intermediate can be isolated (i.e., prevented from participation in the processes that would normally follow its formation). If isolation is impossible, then the techniques available for the study of stable intermediates are the same as those for the study of highly reactive species. For a detailed discussion of appropriate experimental techniques, consult the references listed in Section 3.2.2 or the review by Wayne (1). 

Pudzianowski. 1995. ASystematic Appraisal of Density Functional Methodologies for Hydrogen Bonding in Binary Ionic Complexes. J. Phys. Chem. 100, 4781. 

The mechanism of this reaction was studied in detail, using high-pressure UV and IR spectroscopy. The first step is a fast thermal reaction of cobalt acetate with syn-gas and phosphine to from the ionic complex 7. The yellow cation is the photoactive species. 

Because of the different kinds of enzyme, several synthetic models have been proposed which can be evaluated with regard to their composition and structure or to particular features of the enzymatic function. One of the most successful, proposed by Crabtree and co-workers some years ago,416 involves the ionic complex [NiL2]Cl2 (144 L = 2-HOC6H4CH = N-NHC(S)NH2). 

Likewise, cationic acceptors afford mixed (positively) charged complexes with electron-rich donors,11 i.e., [D, A+] and anionic donors associate with electron-poor acceptors to form mixed (negatively) charged complexes,12 i.e., [D-, A]. In each case, the intermolecular (ionic) complexation or association represents the highly oriented organization of the donor/acceptor pair (independently of whether they bear positive, negative or no charge) that is often sufficient to afford crystalline complexes amenable to direct X-ray structure elucidation.13... 

It is generally assumed that the Lewis acid in 3 decreases the charge on the metal, i.e., increases its electrophilicity. The removal of charge from the nickel allows additional electron donors to coordinate to the nickel atom, and reaction with, for example, 2 moles of carbon monoxide or 1 mole of 1,5-cyclooctadiene (COD) gives the insoluble, catalytically inactive and presumably ionic complexes 7 and 8. In contrast, 7r-allyl-nickel halides (1) add only 1 mole of carbon monoxide while they do not react with COD (52). 

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