Complexes cationic

The solid readily dissolves chemically in concentrated hydrochloric acid, forming a complex, and in ammonia as the colourless, linear, complex cation [H3N -> Cu <- NHj] (cf AgCl) if air is absent (in the presence of air, this is oxidis to a blue ammino-copper(II) complex). This solution of ammoniacal copper(I) chloride is a good solvent or carbon monoxide, forming an addition compound CuCl. CO. H2O, and as such is used in gas analysis. On passing ethyne through the ammoniacal solution, a red-brown precipitate of hydrated copper(I) dicarbide (explosive when dry) is obtained ... 

Silver chloride is readily soluble in ammonia, the bromide less readily and the iodide only slightly, forming the complex cation [Ag(NH3)2]. These halides also dissolve in potassium cyanide, forming the linear complex anion [AglCN) ] and in sodium thiosulphate forming another complex anion, [Ag(S203)2] ... 

If the coordination entity is negatively charged, the cations paired with the complex anion (with -ate ending) are listed first. If the entity is positively charged, the anions paired with the complex cation are listed immediately afterward. 

Alkali or alkaline-earth salts of both complexes are soluble in water (except for Ba2[Fe(CN)g]) but are insoluble in alcohol. The salts of hexakiscyanoferrate(4—) are yellow and those of hexakiscyanoferrate(3—) are mby red. A large variety of complexes arise when one or more cations of the alkah or alkaline-earth salts is replaced by a complex cation, a representative metal, or a transition metal. Many salts have commercial appHcations, although the majority of industrial production of iron cyanide complexes is of iron blues such as Pmssian Blue, used as pigments (see Pigments, inorganic). Many transition-metal salts of [Fe(CN)g] have characteristic colors. Addition of [Fe(CN)g] to an unknown metal salt solution has been used as a quaUtative test for those transition metals. 

The existence of half-salt complex cations formed by the association of an ammonium cation B", with a neutral molecule, B, has also been postulated. 

The crown ethers and cryptates are able to complex the alkaU metals very strongly (38). AppHcations of these agents depend on the appreciable solubihty of the chelates in a wide range of solvents and the increase in activity of the co-anion in nonaqueous systems. For example, potassium hydroxide or permanganate can be solubiHzed in benzene [71 -43-2] hy dicyclohexano-[18]-crown-6 [16069-36-6]. In nonpolar solvents the anions are neither extensively solvated nor strongly paired with the complexed cation, and they behave as naked or bare anions with enhanced activity. Small amounts of the macrocycHc compounds can serve as phase-transfer agents, and they may be more effective than tetrabutylammonium ion for the purpose. The cost of these macrocycHc agents limits industrial use. 

Drying agents containing complexable cations such as or Na should be avoided. 

In the absence of die polyether, potassium fluoride is insoluble in benzene and unreactive toward alkyl halides. Similar enhancement of solubility and reactivity of other salts is observed in the presence of crown ethers The solubility and reactivity enhancement result because the ionic compound is dissociated to a tightly complexed cation and a naked anion. Figure 4.13 shows the tight coordination that can be achieved with a typical crown ether. The complexed cation, because it is surrounded by the nonpolar crown ether, has high solubility in the nonpolar media. To maintain electroneutrality, the anion is also transported into the solvent. The cation is shielded from interaction with the anion as a... 

This remarkable group of compounds was introduced by Lehn and his co-workers in Strasbourg . They are macrobi-, macrotri-, or macropolycyclic compounds which are similar to the in-out amines illustrated above, but they have crown-like bridges throughout. Because of their ability not only to complex cations but to encapsulate... 

This is a term introduced by Gokel and co-workers only very recently. The compounds included in this class are those which have single macrorings like crowns but additional pendant donor groups which make them similar in some respects to crytands. The presumption from which the name derives is that a complexed cation will be bound by both the macroring and the sidechain in much the same fashion as a lasso binds an animal. The compounds are named as simple crown derivatives and are illustrated as 16 a 17 below. 

In later work, Vogtle and his coworkers prepared analogs of both crown ethers and cryptands. These molecules are designed to have a terminal donor group which is capable of offering a complexed cation additional binding sites. Numerous... 

Since Pressman s early observation that antibiotics of the nigericin type complexed cations there has been considerable effort expended to mimic this action using simple, readily synthesized molecules. Simon and his collaborators have been especially active in this approach and have reviewed this area . They have devised a number of struc-... 

Ms " clusters have 12 framework bonding electrons as has [BsHs]- (p. 161) the anions are also isoelectronic with the well-known cation [Bis]. Similarly, the alloy NaSn. 2.23 reacts with cryptand in ethylenediamine to give dark-red crystals of [Na(ciypt)]4 [Sng] the anion is the first example of a C41, unicapped Archi-median antiprism (Fig. 10. lOc) and differs from the >3/, structure of the isoelectronic cation [Bis] + which, in the salt Bi+[Bi9] +[HfCl6]5 (p. 591), features a tricapped trigonal prism, as in [BgHg] " (p. 153). The emerald green species [Pb9] , which is stable in liquid NH3 solution, has not so far proved amenable to isolation via ciyptand-complexed cations. 

Temperature 10 -10 faster from 0° to 100° Complexing cations Often much faster... 

By contrast, reaction of XeFi with the iridium carbonyl complex cation [Ir(CO)3(PEt3)2] in CH2CI2 results in addition across one of the Ir-CO bonds to give the first example of a metal fluoroacyl complex ... 

JA5190, 940M5132). Proton abstraction from 109 gives a neutral ti C) 2-thienyl complex, 110. Such a reaction becomes impossible in case of the 2,5-dimethylthiophene analog of 109. However, use of a strong base such as potassium hydroxide in methanol gives 111. An attempted transformation of 109 to 110 by protonation with triflic acid leads, however, to the thienylcarbene complex cation 112 where the aromaticity is disrupted. 

The complex cation [Cp(Ti -2,5-dimethylthiophene)Fe] " with 3,4-dimethyl-phosphole gives the a complex 234 on photolysis [84JOM(272)417]. 

A certain coordination compound has the simplest formula Pt HjC. It has a molar mass of about 600 g/mol and contains both a complex cation and a complex anion. What is its structure ... 

Ionophores constitute a large collection of structurally diverse substances that share the ability to complex cations and to assist in the translocation of cations through a lipophilic interface.1 Using numerous Lewis-basic heteroatoms, an ionophore organizes itself around a cationic species such as an inorganic metal ion. This arrangement maximizes favorable ion-dipole interactions, while simultaneously exposing a relatively hydrophobic (lipophilic) exterior. 

Figure 6. Concentration of the complexing cations MEP1 (A) and MEM1 (0) in the complex electrolyte phase during one total charge-discharge cycle of a model zinc-flow battery. Taken from Ref. [90],...

Isothermal studies at 370—420 K have been made of the kinetics of decomposition of [Co(NH3)6](N3)3, [Co(NH3)5(N3)](N3)2 and both cis-and frarcs-[Co(NH3)4(N3)2](N3) [1120]. Results are interpreted as indicating the operation of a common reaction mechanism which is not greatly influenced by either the constituents or the stereochemistry of the complex cation. The reactions of all four compounds may yield either CoN or Co(NH3)2(N3)2 as the residual product the alternative decompositions may be represented as... 

The name of a coordination compound (as distinct from a complex cation or anion) is built in the same way as that of a simple compound, with the cation named before the anion ... 

Quantum chemical calculations have shown themselves to be a useful methodic supplement to the spectrum of experimental techniques for investigating reaction mechanisms. This has also been pointed out for the field of cationic polymerization. It is particulary advantageous because individual interactions from the complex cationic reaction system, which is usually very complicated, can be treated separately by means of these calculations. 

Let us now examine the consequences of the formation of a donor-acceptor bond in a little more detail. If the donor - acceptor bond is completely covalent, then we record net transfer of one unit of charge from the donor to the acceptor as a direct consequence of the equal sharing of the electron pair between the two centres. This result leaves a positive charge on the donor atom and a negative charge on the acceptor atom. The limiting ionic and covalent descriptions of a complex cation such as [Fe(H20)6] are shown in Fig. 1-1. 

Aqueous solution containing EDTA complexed cations... 

The complexes formed with Hg2(N03)2 have a chain structure with the ligand joining Hg—Hg units together as in V, whereas those with Hg2(CI04)2 contain complex cations as in VI ... 

Polysulfides with two-valent complex cations, e.g., [M(N-methyhmida-zole)6]Ss have been prepared with M = Mn, Fe, Ni, Mg [51]. 

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