Reaction of Two Metal Compounds

In some cases, it is possible to carry out a reaction of two metal compounds directly to prepare a complex. One such reaction is the following ... 

A variation of the reaction of two metal compounds occurs when one metal complex already containing ligands reacts with a simple metal salt to give a redistribution of the ligands. For example, such a reaction takes place between [Ni(en)3]Cl2 and NiCl2 ... 

In subsequent research, it turned out that two-state reactivity can also provide a concept for the understanding of oxidation reactions way beyond the scope of gas-phase ion chemistry and can actually resolve a number of existing mechanistic puzzles. In enzymatic oxidations involving cytochrome P450, for example, changes in spin multiplicity appear to act as a kind of mechanistic distributor for product formation [27-29], and in the case of manganese-catalyzed epoxidation reactions, two-state scenarios have been put forward to account for the experimentally observed stereoselectivities [30-32], Two-state reactivity is not restricted to oxidation reactions, and similar scenarios have been proposed for a number of other experimentally studied reactions of 3d metal compounds [33-37]. Moreover, two-state scenarios have recently also been involved in the chemistry of main group elements [38]. The concept of two-state reactivity developed from the four-atomic system FeO /H2... 

Organic compounds M—R and hydrides M—H of main group metals such as Mg, Zn, B, Al, Sn, SI, and Hg react with A—Pd—X complexes formed by oxidative addition, and an organic group or hydride is transferred to Pd by exchange reaction of X with R or H. In other words, the alkylation of Pd takes place (eq. 9). A driving force of the reaction, which is called transmetallation, is ascribed to the difference in the electronegativities of two metals. A typical example is the phenylation of phenylpalladium iodide with phenyltributyltin to form diphenylpalladium (16). 

Nitrogen forms binary compounds with almost all elements of the periodic table and for many elements several stoichiometries are observed, e.g. MnN, Mn Ns, Mn3N2, MniN, Mn4N and Mn tN (9.2 < jc < 25.3). Nitrides are frequently classified into 4 groups salt-like , covalent, diamond-like and metallic (or interstitial ). The remarks on p. 64 concerning the limitations of such classifications are relevant here. The two main methods of preparation are by direct reaction of the metal with Ni or NH3 (often at high temperatures) and the thermal decomposition of metal amides, e.g. ... 

Numerous intercalation reactions are known in which one reactant enters the lattice of the other. Such behaviour is conveniently illustrated by reference to two recent studies. Lithium undergoes a low temperature (298 K) topochemical reversible reaction with transition metal compounds (e.g. TiS2, NbSe3) [1211] in which the host lattice structure may be partially retained (e.g. in Li TiS2, LijNbSe3). The reaction [1212]... 

It is possible for an element and a compound of that element or for two compounds containing a common element to react by combination. The most common type in general chemistry is the reaction of a metal oxide with a nonmetal oxide to produce a salt with an oxyanion. For example,... 

In view of the extensive and fruitful results described above, redox reactions of small ring compounds provide a variety of versatile synthetic methods. In particular, transition metal-induced redox reactions play an important role in this area. Transition metal intermediates such as metallacycles, carbene complexes, 71-allyl complexes, transition metal enolates are involved, allowing further transformations, for example, insertion of olefins and carbon monoxide. Two-electron- and one-electron-mediated transformations are complementary to each other although the latter radical reactions have been less thoroughly investigated. 

In a similar manner, Jt-allyl complexes of manganese, iron, and molybdenum carbonyls have been obtained from the corresponding metal carbonyl halides [5], In the case of the reaction of dicarbonyl(r 5-cyclopentadienyl)molybdenum bromide with allyl bromide, the c-allyl derivative is obtained in 75% yield in dichloromethane, but the Jt-allyl complex is the sole product (95%), when the reaction is conducted in a watenbenzene two-phase system. Similar solvent effects are observed in the corresponding reaction of the iron compound. As with the cobalt tetracarbonyl anion, it is... 

Another useful method of preparing organolithium reagents involves metal-metal exchange. The reaction between two organometallic compounds proceeds in the direction... 

Homologues of ethoxyacetylene can be obtained by reaction of the metallated ethynyl ether in liquid ammonia with primary alkyl bromides and iodides 167]. Because of their better solubiliiy, the lithium compounds are preferred over their sodium and potassium analogues, lithium ethoxyacetylide is generated from the readily accessible 2-bromovinyl ethyl ether and two equivalents of lithium amide. This starting compound is obtained as a mixture of the E-and Z-isomer. When this mixture is heated with powdered KOH, only the Z-isomer is converted into ethoxyethyne. Alkali amides are able to conven both isomers into ethoxyethyne and its alkali compounds. A possible explanation for this violation of the "rule of... 

The compounds of elements of the first three columns of the periodic system are not reduced by hydrogen, and those in the subsequent columns only partly so. At high temperatures TiCl4 is easily reduced to TiCl3, but the reaction proceeds no farther because the charge of the titanum ion is reduced. Further complications can occur in the reaction of a metal with a compound if the two metals can, themselves, combine to give a compound. In such instances the reaction will proceed in quite a different way from that expected from the stability rules. Because of the different heats of formation of halides and chalcides it can happen that a given element, for example Na, can reduce a chloride but not an oxide. 

Metal ions can act as electron-pair acceptors, reacting with electron donors to form coordination compounds or complexes. The electron donor species, called the ligand, must have at least one pair of unshared electrons with which to form the bond. Chelates are a special class of coordination compound which results from the reaction of the metal ion with a ligand that contains two or more donor groups. 

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