Group 10 VIII complexes

Table III. Oxidation of TME in the Presence of Group VIII Complexes and [ (CsHr VCh]"...

In work reported elsewhere (31) we have shown that the oxidation of styrene under mild conditions is promoted by many group VIII metal complexes. The product profile depends on the nature of the metal center and often differs from that observed when radical initiators are used (Table IX). Substantial quantities of styrene oxide are found in some cases but not in others (31). The epoxide which is formed, however, seems to arise via the co-oxidation of styrene and formaldehyde which is formed by oxidative cleavage of the double bond. Formaldehyde may be oxidized to performic acid or formylperoxy radicals which are efficient epoxidizing agents. Reactions of styrene with oxygen in the presence of group VIII complexes exhibit induction periods and are severely retarded by radical inhibitors (31). Thus, the initial step in the oxidation of styrene in the presence of the Ir(I),Rh(I), Ru(II), and Os(II) com-... 

We are here concerned with various organometallic reactions for which there is evidence that organic free radicals are implicated in the reaction pathway. Many of these arc formally two-electron oxidative additions or their retrogressions, the reductive eliminations (Section V,A). We shall focus attention on systems in which transition metal Group VIII complexes are involved. 

Oxidative addition of halogen-containing compounds to organo-group VIII complexes dates from the 1950s ... 

A variety of other molecules react with group VIII complexes, and the format of this series prohibits an all-inclusive survey. This section describes reactions of selected addenda. 

Oxidative addition to ruthenium and osmium four-coordinate complexes occurs readily. These complexes are excellent starting materials for group VIII complexes. Addition of formaldehyde to complexes M(CO)L(PPh3)2 (L = CO or PPhs selection of L is metal dependent) leads to oxidative addition products, a reaction of relevance to Fischer-Tropsch processes. The ruthenium complex is proposed as an intermediate only the osmium complex has been isolated ... 

The great importance of group VIII complexes in homogeneous catalysis has focused more attention on their insertion chemistry, but the number of authenticated insertions of monoalkenes into M-H bonds is small. Insertions of dienes and allenes are more numerous because of the greater thermodynamic stability of the product xt-allyl complexes. Some examples of insertions of complexes of group VIII are listed in Table... 

Photosubstitution and Photoisomerization 13.2.3. with Group VIII Complexes... 

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