Neutrally charged ligands

The stoichiometiy of a metal complex is described by its chemical formula. For example, each cation of the silver-ammonia complex contains one Ag cation bound to two neutral NH3 ligands and carries a net charge of -i-l, as shown in Figure 18-11. The formula of a complex ion is enclosed in square brackets, as in [ Ag (NH3)2. The... 

Equilibria Where a Neutral Molecule Is Exchanged. The difficulties discussed above for proton transfer and electron transfer equilibria involving multiply charged ions are not present when neutral molecules (ligands) which are complexed to a given ion are exchanged. Equation 43 is a typical example ... 

Bonds between many neutral ligands and transition metal atoms in low oxidation states, have mean bond disruption enthalpies in the range 80-200 kJ mol 1 (9). Bonds to charged ligands, e.g. 

A very different neutrally charged complex for alkane activation has been reported recently and is shown in Scheme 34(A). The compound is a hydridoplatinum(II) complex bearing an anionic ligand based on the familiar nacnac-type, but with a pendant olefin moiety (97).This complex is extremely soluble in arenes and alkanes and activates C-H bonds in both types of hydrocarbons. This is indicated by deuterium incorporation from deuterated hydrocarbon into the substituents on the arene of the ligand and into the Pt hydride position (A A-d27, Scheme 34). The open site needed for hydrocarbon coordination at Pt(II) is created by olefin insertion instead of anion or solvent substitution (97). 

When writing the formula of a complex, the symbol of the metal is written first, then the negatively charged ligands, followed by the neutral ligands. Finally, the formula of the complex ion is enclosed within square brackets as in, for example, [Fe(0H)2(Hp)J+. This ion has an overall charge of -rl as this is the sum of the Fe + ion and the two 0H ions. 

In spite of the simple theoretical treatment of the electrochemical alkali ion selectivity for liquid membranes incorporating electrically neutral ligands, nothing comparable has been achieved for negatively charged ligands. As shown in Table 6 for this type of membrane, two completely different expressions for the selectivity constant can be derived (27, 25, 26), depending on which assumptions are made ... 

Although one might think of neutral anion carriers for use in membrane electrodes, I cannot offer good suggestions. It is possible, however, to use charged ligands (classical ion exchangers) as membrane components. This makes accessible the measurement of, for example, Cl- and HCO in blood serum, without serious mutual interference. 

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