Organometallic Co

The formation of high polymers of olefins in the presence of titanium halogenides with no specially added organometallic co-catalysts was discovered long ago [see (147), and the references therein], A complete description of various alkyl-free polymerization catalysts based on the use of transition metal chlorides may be found in the review by Boor (17), where a comparison of these catalysts with traditional two-component systems is given. 

MoBr3-acidic or organometallic co-catalysts Mo(OEt)5 (with/without EtAlCL or Et3Al)... 

Although both the alkyl complex [Co(nor)4] (Figure 15) and the hydride complex [Co(C5Me5)(Si(H)Ph2)2(H)2] (Figure 16) offer well-characterized examples of organometallic Co(IV) and Co(V) complexes, the situation with classical coordination complexes is much less clear. 

Much work has been done on solvated metal complexes by Merbach and co-workers. These pressure studies have been extended to organometallic CO and SO complexes plus, interestingly, the first dihydrogen aqua-complex, Ru(H2)(H20)s, (20), produmi as shown in Equation (9) ... 

The structure and coordination of coenzyme B,2 are unusual in several aspects. It is an organometallic Co(III) complex with a cobalt-carbon bond to the 5 -carbon of 5 -deoxyadenosine. The four coordination positions in the plane are occupied by nitrogens from a corrin ring. The pyrrole rings are designated A through D, as shown in... 

Nb and Ta halides and their mixtures with suitable organometallic co-catalysts (similar to those for Mo and W halides) work as excellent catalysts for the polymerization of various disubstituted acetylenes, while they cyclo-trimerize monosub-stituted acetylenes. This is probably because the steric hindrance of disubstituted monomers can hamper the cyclo-trimerization to selectively give polymers. A problem with Nb and Ta catalysts is that they are deactivated by polar groups in the monomer and solvents. 

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