Coordination compounds counter ions

This Formula Index consists of over 28 000 compounds that occur in the 6562 text pages of Volumes 1-6. Indexed compounds may appear in the text, equations, Schemes, Figures or Tables. Only specific compounds and not general classes of compound have been indexed the counter ion has been excluded. Limitations of space do not permit every coordination compound to be indexed each time it is mentioned, therefore compounds are only indexed when considered to be important in the context of the topic under discussion. 

The variations in ionic radii of the transition elements of the 4th period serve to exemplify the arguments needed to rationalize similar variations in the other transition series. Figure 7.3 includes a plot of the radii of the 2 + ions of those transition elements of the 4th period that form them. The plot includes the radius of the Ca2+ ion, which represents the beginning of the series but has no 3d electrons, as also has the Zn2+ and Ga3+ ions (both 3d10) at the end of the series. The radii are those of octahedrally coordinated ions as they are found in crystalline compounds, the counter-ions (i.e. the ions of opposite charge) being situated at the vertices of an octahedron, as shown in Figure 7.4. 

As in other fields of inorganic chemistry, some research on coordination compounds has been carried out in non-aqueous media. There are several reasons for this first, some compounds are not soluble in water, but will dissolve in other solvents (of course, solubilities can often be modified by judicious selection of the counter ion). In those cases in which the coordination compound reacts with water, the use of a non-aqueous solvent may be advantageous. A familiar example is the determination of the number of ions in a compound by measuring the conductivity in nitromethane or other highly polar solvent. In studying the self-exchange rate of the [Co(NH3)6]2+/3+system,... 

The search in recent years for silicon compounds with multiple bonds or cyclic n-systems has renewed interest in siloles (66)77 and their mono- and di-anions (48 and 49), and led to the successful isolation of stable silole anions coordinated to various metal counter ions (Li+, Na+, K+)10a-c 78 - 86 and as complexes with ruthenium (e.g. 6a and 6b)10d. 

Compounds 4.75 and 4.76 formally contain tetravalent silicon, which is not electron-deficient. It is, however, a strong Lewis acid, and on reaction with F , five-coordinate silicon compounds are obtained. In the case of 4.75, the fluoride anion is localised mainly on the boron atom, although it does display dynamic behaviour involving hopping between boron and silicon. Compound 4.76 as the KF adduct contains two five-coordinate silicon atoms that chelate the F anion. The coordination sphere of the K+ counter-ion is completed by a molecule of [18] crown-6 (Figure 4.32a). 

The application of the HSIP is of considerable importance in preparative coordination chemistry because some solid complexes are stable only when they are precipitated using a counter ion conforming to the preceding rule. For example, [CuCl5]3- is not stable in aqueous solution but can be isolated as [Cr(NH3)6][CuCl5]. Attempts to isolate solid compounds containing the complex ion [Ni(CN)5]3- as K3[Ni(CN)5] yield KCN and K2[Ni(CN)4] instead. It has been found, however, that when counter ions such as [Cr(NH3)6]3+ or [Cr(en)3]3+ are used, solids containing the [Ni(CN)5]3- ion are obtained. 

Very few binary compounds of this class have been described, but CIO is widely used as a counter ion for the preparation of many of the cationic species of the other neutral ligands, despite the instability that gives some risk of explosion For many years, it was regarded as the standard for non-coordination —especially in aqueous solution—and both the chlorate and perchlorate crystallized from aqueous solution as [Mn(H20)6]X2. However, the anhydrous Mn(C104)2 can be... 

What is the formula of the compound What is the structure of the complex ion present [Hints Cr3 + is expected to be six-coordinate with NH3 and (possibly) 1 acting as ligands. The I- ions will be the counter ions if needed.]... 

Coordination compound a compound composed of a complex ion and counter ions sufficient to give no net charge. 

Counter ions anions or cations that balance the charge on the complex ion in a coordination compound. (20.3) Covalent bonding a type of bonding in which electrons are shared by atoms. (2.7 13.1)... 

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