Organometallic-chelate compounds

The following synthesis is an excellent general method for preparing organometallic chelate compounds and is an example of a salt-plus-salt procedure which produces a soluble jS-diketone derivative and an insoluble by-product. The advantages of such salt-plus-salt syntheses have been discussed previously. In the case considered here, the desired complex should not be prepared by the simple reac-... 

This paper calls attention to the need for new ions in coordination chemistry—ions that would permit more detailed physico-chemical studies to be made, ions that would facilitate studies of less familiar metals and of less familiar coordination numbers, and ions that would help studies of chemical bonding and reaction mechanisms. Organometallic ions of the type RmM+ are such ions, and these form metal-chelate compounds of the type RmM Ch) . Three aspects of the chemistry of organometallic-chelate compounds are described (1) equilibria of compound formation ( ) kinetic and mechanistic studies of three types of reactions (a) reactions of the coordinated ligand, (b) substitution at the 4-, 5-, or 6-coordinate metal atom, and (c) reactions of the organic moiety and (3) studies of stereochemistry and chemical bonding. 

Probably more formation constants of organometallic-chelate compounds will be determined because of the importance of understanding mechanisms of reactions of these compounds. 

The use of organometallic ions as central metal ions not only increases the scope of inorganic reactions, but also increases the opportunity for detailed studies of these reactions because favorable properties (including solubility and volatility) are enhanced, and because it is now possible to place a probe on the metal. Possible reactions of organometallic-chelate compounds seem to be of three types. 

Presumably, because of the enhanced volatility and solubility of organometallic-chelate compounds, it should be possible to carry out mechanistic studies not only in a wide range of solvents but also in the liquid or ansolvous phase and in the gas phase. 

The Lo-Cat process, licensed by US Filter Company, and Dow/Shell s SulFerox process are additional liquid redox processes. These processes have replaced the vanadium oxidizing agents used in the Stretford process with iron. Organic chelating compounds are used to provide water-soluble organometallic complexes in the solution. As in the case of Stretford units, the solution is regenerated by contact with air. 

Related to jS-diketones are metalla-/ -diketones, whose distinctive chemistry is a recent development. In these, the methine group of a conventional diketonate is replaced with an organometallic moiety such as m-Mn(CO)4, m-Re(CO)4, /<2c-Mn(CO)3(RNC) or C5H5Fe(CO).519 Exemplary is Al Mn(MeCO)2(CO)4 3, which is prepared in a two-step synthesis. Addition of methyllithium to Mn(CO)5COMe forms Li[Mn(MeCO)2(CO)4] which, when treated with aluminum chloride, provides the tris(chelate) compound.520 An X-ray study showed that the MnC202Al ring is essentially planar with Mn—C(acyl) bond distances indicative of a bond order of ca. 1.2. The O—O bite distance, 2.73 A, is about the same as that of acetylacetonate in Al(MeCOCHCOMe)3.521 As in the... 

The types of compounds that can be separated by liquid-liquid chromatography include fatty acids, amino acids, organometallics, chelates, alcohols, amines, hydrocarbons, pesticides, herbicides, steroids, hormones, alkaloids, and antilnotics. A number of such separations have been illustrated by Schmit. ... 

Ionic grafting usually leads to well defined copolymers due to the limited (if any) termination reactions. Anionic sites can be created by metallation of the backbone. This can be accomplished by complexation of several types of C-H bonds (allylic, benzylic, aromatic) with organometallic compounds such as sec-BuLi. Usually chelating compounds, for example N,N,N/>N/-tetra methyl ethylene diamine (TMEDA), act as solvating bases facilitating the reaction. By this method PB-g-PS [36-38] and Pl-g-PS [39] graft copolymers have been prepared. 

Atomic emission spectral detection of metallic elements in GC shows something of an irony while detection limits and selectivities are usually better than for non-metals, because of greater emission intensities and absence of background interferences in the spectral region monitored, GC applications for metallic compounds in general are less common than for non-metals. However, many volatile binary metal and metalloid compounds, organometallic and metal chelate compounds can be quantitatively gas chromatographed [1], and some of the possible GC-... 

In his original paper,2 Cram disclosed an alternative model that rationalizes the preferred stereochemical course of nucleophilic additions to chiral carbonyl compounds containing an a heteroatom that is capable of forming a complex with the organometallic reagent. This model, known as the Cram cyclic or Cram chelate model, has been extensively studied by Cram9 and by others,410... 

The solubility of most metals is much higher when they exist as organometallic complexes.4445 Naturally occurring chemicals that can partially complex with metal compounds and increase the solubility of the metal include aliphatic acids, aromatic acids, alcohols, aldehydes, ketones, amines, aromatic hydrocarbons, esters, ethers, and phenols. Several complexation processes, including chelation and hydration, can occur in the deep-well environment. 

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