Metal-containing groups, attachment

Many other metal-containing groups have been attached to organic polymers. Polymers 51 containing Pd-G cr-bond linkages have been successfully prepared by the radical polymerization of / -substituted styrene derivatives (Equation... 

Rule 3 For even open polyenes (e.g. fy -butadiene) nucleophilic attack at the terminal carbon atom is always preferred, for odd open polyenyls attack at the terminal carbon atom occurs only if the attached metal containing group is strongly electron-withdrawing. 

The structures of the dinuclear metal carbonyls (containing two metal atoms) involve either metal-metal bonds or bridging CO groups, or both. For example, the structure of Fe2(CO)9, diiron nonacar-bonyl, contains three CO ligands that form bridges between the iron atoms, and each iron atom also has three other CO groups attached only to that atom. 

The energy factored force field for carbonyls contains interaction parameters as well as stretching parameters. Such parameters are invariably required to be positive, for CO groups attached to the same metal, by the experimental finding that symmetric combinations of the individual CO vibrations occur at higher frequencies than similar antisymmetric combinations. 

Enzymes are protein catalysts of remarkable efficiency and specificity. Lipid, carbohydrate, nucleotide, or metal-containing prosthetic groups may be attached to these enzymes and serve as essential components of their catalyses by enhancing specificity and/or stability (8—13). Each enzyme has a specific temperature and pH range where it functions to its optimal capacity the optima for these proteins usually He between 37—47°C, and pH optima range from acidic, ie, 1.0 in the case of gastric pepsin, to alkaline, ie, 10.5 in the case of alkaline phosphatase. However, enzymes from extremely thermotolerant bacteria have become available these can function at or near the boiling point of water, and therapeutic use of these ultrastable proteins can be anticipated. 

Studies on various derivatives of ferrocene, cymantrene, benzene-chromium tricarbonyl, and butadieneiron tricarbonyl were recently reported (174, 176). Carbonyl derivatives containing the COR group lose CO to give an ion probably containing the R group attached to the metal, e.g. 

What reference to Tables I—III does not indicate, however, is any indication of a compound containing more than two trifluoromethyl groups attached to a metal atom, or many examples of early transition metal trifluoromethyl derivatives. The early results of a number of synthetic techniques designed to ultimately result in more general routes to the preparation of trifluoromethylated transition metal compounds are presented below. 

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