Ions, complex negative

Nahir TM, Buck RP, Transport processes in membranes containing neutral ion carriers, positive ion complexes, negative mobile sites, and ion pairs. J. Phys. Chem. 1993 97 12363-12372. 

Fig. 10 L Fluorescence microscopy images of MTP walls after incubation with selected ions (10 M, MeCN). Each square represents an individual signal of the whole response pattern arrays. Right. Plot of the normalised fluorescence emission intensity changes in each sensing system of the arrays upon metal ion complexation. Negative values indicate a quenching of fluorescence, while positive values indicate increase of fluorescence intensity. Reprinted with permission fiom [50]...

In this particular case the binding of an alkaline or alkaline earth metal ion to the crown ether decreases the stability of the host with u-allose (negative allosterism), since the conformation of the crown-ether changes due to the metal ion complexation [264-268]. 

In a free metal ion without any ligands, all five d orbitals have identical energies, but what happens to the d orbitals when six ligands are placed around a metal in octahedral geometry The complex is stabilized by attractions between the positive charge of the metal ion and negative electrons of the ligands. At the same time,... 

Attempts to obtain alkylcarbonium complexes by dissolving alkyl chlorides (bromides) in liquid Lewis acid halides (stannic chloride, titanium (IV) chloride, antimony pentachloride, etc.) as solvent were unsuccessful. Although stable solutions could be obtained at low temperature with, for example, t-butyl chloride, the observed N.M.R. chemical shifts were generally not larger than 0 5 p.p.m. and thus could be attributed only to weak donor-acceptor complexes, but not to the carbonium ions. The negative result of these investigations seems to indicate that either the Lewis acids used were too weak to cause sufficient ionization of the C—Cl bond, or that the solvating effect of the halides... 

A few carbon compounds are considered to be inorganic. These include carbon dioxide, CO2, and and carbon compounds containing complex negative ions (for example, CO32-, HCO3-, and 0CN-). 

The nature Of the ions.—In 1814, G. F. Parrst12 found that in the electrolysis of aq. soln. of potassium ferrocyanide the alkali accumulated about the negative pole, and ferric oxide and hydrocyanic acid about the positive pole, and the work of J. F. Daniell and W. A. Miller, and of W. Hittorf (1859), showed that double salts are of two kinds, and that in the one kind the metal is bound as a complex negative ion, and in the other it is the positive ion. For example, in the electrolysis of potassium silver cyanide, KCy.AgCy, W. Hittorf (1859) found that silver was deposited on the cathode, whereas with salts of the type AgN03 it is deposited on the anode. Hence, it was inferred that the salt ionizes KAgCy2=K,- -AgCy2 similarly,... 

Up to now wTe have only considered complexes with a central positive ion, but there exist some complex ions in which the central ion is negative, the best-known example being the NH " ion. Ammonium compounds differ in stability, and from the reaction. 

All of these metal complexes are isoelectronic and isostructural with each other. Upon coordination of the carbon monoxide to the nickel(O) centre, the metal ion acquires negative charge. The carbon monoxide ligand possesses empty 7r -orbitals, and back-donation from the metal to the ligand reduces the electron density on the metal. 

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